The Proceedings of 2023 International Conference on Wireless Power Transfer (ICWPT2023)

Taking the cold end system with dual-pressure condenser of a 1000 MW coal-fired unit as the research object, considering real-time parameters during operation, the full working conditions real-time optimization model was established. Based on the historical operation data, the accuracy of the model was verified, the influence of changes in real-time state parameters such as load, circulating water inlet temperature and clean coefficient on the optimization calculation results was analyzed, and the optimal circulating pump operation mode and energy saving potential under calculated working conditions were obtained. The calculation results showed that, 63.44% of the calculation conditions had achieved energy saving effect, and the cumulative income could reach 604.16 MW·h, the optimal operation modes of the circulating water pump were more necessary to reasonably determine Under the working conditions of high load and high inlet water temperature.

Oil energy is very important for national development, but with the exploitation of oil resources, the emergence of high water content oil reduces the combustion efficiency. Therefore, timely monitoring of oil moisture content is very important for subsequent oil exploitation. Based on the principle of electromagnetic induction, a sensor array consisting of 8 excitation coils and 12 detection coils is designed to monitor the oil water content in the pipeline. The experiment verifies that the induced voltage is proportional to the moisture content. The experimental results show that the presence of pipeline defects increases the value of induced voltage, but does not change the trend of induced voltage. At the same time, when the number of coils in the sensor array is between 500 and 1000 turns, the sensitivity of the overall monitoring system reaches the best, and too much or too little will affect the result. This is of great significance for improving the efficiency of oil extraction and ensuring energy supply.

Effective detection of partial discharge faults is of vital importance for ensuring efficient power transmission. Currently, there are various partial discharge signal detection methods, such as the differential method and high-frequency current detection method. However, these methods suffer from low detection accuracy and narrow signal bandwidth. In this paper, the Hilbert fractal antenna is chosen as the research subject. The Hilbert antenna is an ultra-wideband, small-sized antenna that offers high detection accuracy and a broad detection bandwidth. As the location of the feed point affects the impedance matching and antenna parameters, optimizing the feed point position can significantly impact antenna performance. Through simulation and optimization using HFSS software, the feed point of the fourth-order Hilbert fractal antenna is selected and optimized. Additionally, the lengths of three different conductors, substrate thickness, and conductor width are also optimized. The optimization results demonstrate that within the frequency range of 0.3 GHz to 3 GHz, there are four resonant points. The overall bandwidth reaches 400 MHz within the range of 0.3 GHz to 1 GHz, and the antenna exhibits good overall directivity. The antenna exhibits suitable dimensions and excellent performance, making it suitable for capturing ultra-high-frequency signals of partial discharges in cables.

In the high permeability environment, the use of LC (LCL) filters on the AC side of grid-connected photovoltaic inverters can effectively reduce the size and capacity of the filters. However, it can lead to filter resonance issues. The active damping control method can avoid filter resonance problems. This study take focuses on the three-level photovoltaic grid-connected inverter by using a virtual resistor based on the differential of capacitor voltage to generate capacitor current, the active damping scheme suppresses the resonance of the inverter output current without additional sensors. The robustness of this scheme under different grid short-circuit capacities is analyzed. Finally, the feasibility of the algorithm is validated on a 30 kW three-level grid-connected inverter experimental platform.

The −200 kV high-voltage power supply serves as the acceleration power supply for the Comprehensive Research Facility for Fusion Technology neutral beam injector (CRAFT NNBI) system, and its operation entails strict requirements to ensure its dynamic and steady-state performance. This article proposes a power supply topology for its application based on phase-controlled rectification, a three-level NPC inverter, a boost converter transformer, and high-voltage uncontrollable rectification (AC-DC-AC-DC). This topology provides a structural advantage by enabling control functionality on the low-voltage side, thereby eliminating the need for control functions on the high-voltage side. The boost converter transformer ensures electrical isolation between the high-voltage and low-voltage sides, while the precise control of the output voltage is coordinated by the phase-controlled rectifier and NPC inverter. Coarse adjustment is achieved through regulation of the DC bus voltage while the duty cycle of the NPC can be adjusted for fine-tuning. The quality of the DC output voltage is controlled through a combination of phase-controlled rectification and the NPC inverter to ensure the stability, accuracy, and ripple requirements of the final high-voltage DC side. This article also provides a detailed analysis of the hardware selection and feedback control of the system through a simulation of the power supply using MATLAB/Simulink software. The experimental tests and simulation results consistently indicated that the power supply meets the stability and dynamic response requirements necessary for the CRAFT NNBI system’s implementation.

Compared with traditional high voltage direct current (HVDC) transmission, flexible HVDC transmission offers numerous advantages in technology, economy, and environmental protection. However, flexible HVDC systems involve many semiconductor devices such as the insulated gate bipolar transistors (IGBT) and power diodes, which often operate under high-frequency switching, causing severe radiated electromagnetic interference. Accurate forecast of such electromagnetic disturbance is crucial for ensuring the safe and reliable operation of the flexible HVDC transmission systems. To achieve this goal, a three-dimensional finite element model of the valve towers of the modular multilevel converters (MMC), which are the elementary components of the HVDC transmission systems, has been built. By utilizing the IGBT mathematical model and the direct frequency domain method, the time profiles as well as the frequency spectra of the transient currents of the IGBTs are extracted and imposed to the finite element model as the excitations inducing electromagnetic interference. Furthermore, the finite element model is integrated in a dedicated APP. Taking into account the widely used capacitor voltage sequencing method of sub-modules, a user-friendly and efficient interface was designed based on the Simdroid platform. This interface allows for parametric modelling, straightforward meshing, calculation, and post-processing. The App provides a comprehensive prediction of the electromagnetic disturbance level of the flexible HVDC transmission systems including the near field distribution pattern and far field propagation characteristics under various operation conditions, which is favorable to the design and optimization of the shielding and protection structure of the converter.

Gait analysis is an important means for diagnosing related diseases, guiding rehabilitation, and assessing mobility. Compared with existing methods, the non-contact electrostatic induction detection method for obtaining gait signals has the advantages of being non-wearable, low-cost, and capable of directly obtaining full-cycle gait signals for a long time. This paper proposes a theory and method of non-contact electrostatic gait detection based on the human body’s electrostatic field. The change law of the equivalent capacitance of the human foot to the ground was analyzed and the kinematic equations of the human foot during movement was established. Based on this, a non-contact electrostatic gait signal detection model based on the human body’s electrostatic field was established. Both the simulation curve of the theoretical model and the measured electrostatic gait signal can reflect the gait information of the foot movement, especially initial contact (IC), toe-off (TO), and swing phase, and have high consistency. This research provides a new theoretical basis and feasible technical approach for gait measurement and analysis.

With the advancement of carbon peak and carbon neutrality process, the new generation power system will change in terms of energy structure, load characteristics, power grid form, technical basis and operation characteristics. This brings new requirements and changes to the statistical work of the power grid. To adapt to the new situation of the new generation power system, this paper constructs a scientific and comprehensive set of statistical indicators for the new generation based on the principles of feasibility, universality, systematization and science. Corresponding to the five characteristics of the new generation power system, the statistical indicator system constructed in this paper focuses on the five dimensions as its core: clean and low-carbon, safe and reliable, flexible and intelligent, open and interactive, economic and efficient. It includes a total of 18 secondary indicators and 75 tertiary indicators. The proposed statistical indicator system for the new generation power system covers various aspects of production, operation and decision-making, to accurately reflect the construction of provincial demonstration areas for the new generation power system, as well as a reference value for guiding the efficient and scientific construction of the new electricity system.

Aiming at the problem that the fault type of PV array is difficult to detect, a fault diagnosis method of PV array fault dictionary based on the maximum number of fuzzy faults is proposed. Firstly, the test point with the most fault information is obtained according to the “maximum number of fuzzy faults”, the node voltage is collected as a new fault characteristic before measurement, and then the node voltage value is divided into a fuzzy domain, the center value of the fuzzy domain is calculated, the fault phenomenon set is established, the working code corresponding to each node is obtained, and the fault dictionary is constructed. In the process of fault diagnosis after testing, it is only necessary to measure the new node voltage value and determine the range of its central value to realize the fault diagnosis of the photovoltaic array. The simulation results show that the proposed method has high accuracy, which proves the feasibility and effectiveness of the method.

The avionics equipment used in harsh environment needs to meet the requirements of corresponding overvoltage surge test. The traditional avionics equipment uses two kinds of overvoltage surge suppression circuit, electromagnetic compatibility suppression and linear power limiting, which can meet the requirements of the product, but cannot solve the application problem of high-current avionics equipment. In this paper, two kinds of traditional circuits are explained and compared, the limitations and shortcomings of their application are pointed out, and an improved type of overvoltage surge suppression circuit is proposed and verified by experiment. The circuit passed the 50 V/12.5 ms overvoltage surge test in accordance with the overvoltage surge requirements of GJB181A-2003 and worked normally. In addition, the experimental test results show that the maximum impedance is only 0.98 W in the input voltage range of 18 V–32 V under 400 W load condition. The hybrid improved circuit can solve various problems of traditional overvoltage surge suppression circuit in high current applications, and the performance index and reliability of avionics equipment can be significantly improved by using this circuit.

Variable speed pumped storage units have significant advantages over traditional fixed speed pumped storage units in terms of efficiency and adaptability to operating conditions. Full power frequency converters are key equipment for variable speed pumping and storage units, and studying the application of various frequency converter topologies in large capacity variable speed pumping and storage units is of great significance. This article takes a 100 megawatt variable speed pumped storage unit as an example, and based on existing devices, compares and analyzes three-level back-to-back converter (NPC), five-level back-to-back converter (SMC) The design schemes of Modular Multilevel Converter (MMC) and Modular Multilevel Matrix Converters (M3C) with four topologies applied to high-power, 13.8 kV connected variable speed pumped storage units are compared and analyzed in terms of cost and topology advantages and disadvantages. It can be concluded that NPC and SMC are more suitable for low-voltage situations, and transformers need to be added to increase voltage in high-voltage situations, MMC and M3C have more advantages in high-pressure situations.

Pipeline transportation has become an indispensable way in production and life. However, the emergence of pipeline defects causes great harm, so timely detection of pipeline defects is crucial for all fields. At present, Magnetic Induction Tomography technology is applied to non-destructive health inspection of metal pipelines, which can infer the location of pipeline defects and visually reconstruct them. However, the traditional sensor array consisting of 12 coils can’t accurately recognize the defects categories when detecting defects of different shapes and depths. In order to solve this problem, the sensor array design is improved, which is composed of a pair of Helmholtz coils and 24 side-by-side detection coils. The experimental results show that the optimized sensor array can better recognize the variation amplitude of different defects and improve the identification degree of defects.

When Short-circuit fault occurs at the receiving end of High Voltage Direct Current (HVDC), it is easy to cause voltage instability of the new energy station at HVDC receiving end. Therefore, the mechanism of the interaction between the new energy station and the HVDC receiving end and its influence on the voltage stability are analyzed. Firstly, the mathematical model of the new energy station is established by taking the photovoltaic (PV) station as an example, and its active power-voltage and reactive power-voltage characteristics are deduced. The active-voltage characteristics determine the upper limit of voltage recovery rate at the receiving end. The reactive power-voltage characteristics show that the reactive power characteristics of the new energy station are similar to that of the capacitor. Secondly, through the power flow equation of the HVDC receiving end, the influence of the active power-voltage characteristics on the voltage stability of the receiving end is analyzed. Finally, the deduced active power-voltage and reactive power-voltage characteristics of the new energy station are verified by simulation, and the output active power of the new energy station will affect the voltage recovery rate at HVDC receiving end, and thus affect the voltage stability.

Considering demand response, power-to-gas (P2G), and carbon capture, this article proposes a new virtual power plant (VPP) optimization scheduling model that promotes multi-energy complementarity and low-carbonization of energy. By introducing a synergistic utilization framework of carbon capture power plant (CCPP)-P2G-gas unit, the captured CO2 is utilized as a raw material for power-to-gas, supplying natural gas to the gas unit. Joint scheduling shifts energy consumption of system-related equipment to stabilize renewable energy fluctuations, enabling flexible dispatch and utilization of wind power and photovoltaics. The established high-dimensional nonlinear optimization model is solved using the solver in MATLAB. The simulation results demonstrate the peak-shaving and valley-filling effect of the proposed model, which promotes renewable energy consumption of VPP and effectively reduces costs and carbon emissions.

Before reaching the design lifetime of nuclear power plants, most operating nuclear power plants choose to apply for continued operation, and safety improvements is an important task for nuclear power plants to apply for continued operation. We have studied the operation license renewal (OLE) method for nuclear power plants internationally, and conducted research on the safety improvements analysis requirements in both the license renewal (LR) in the United States and the long term operation (LTO) in IAEA. Firstly, this article summarizes the safety important improvements of systems, structures and components (SSCs) completed by a certain power plant in China to meet the requirements of operating license renewal. Secondly analyzes and evaluates the characteristics of the operating license renewal safety improvements, and provides examples to analyze the key issues of safety important improvements in a certain nuclear power plant. Finally, suggestions are made for the relevant work of nuclear power plants in China.

With the rapid development of the second generation of high temperature superconducting strip, countries around the world began to explore the application of superconducting cable in the power grid, and a number of demonstration lines have been built. The future large-scale application of superconducting cables will face different application scenarios and laying methods. This paper summarizes the main laying methods of relevant projects at home and abroad, analyzes the typical laying methods of superconducting cables and the main influencing factors, proposes the corresponding chilling shrink design and the integrated construction method of “traction-transport-sending” according to the cold shrinkage characteristics of superconducting cables, summarizes the characteristics and application scenarios of laying methods of superconducting cables such as direct burial, duct bank, cable trench and tunnel. It provides guidance for the selection of laying method of superconducting cable in the stage of popularization and application. When superconducting cables are used for long-distance transmission, considering the comprehensive reliability, operation mode and cooling shrinkage response, priority can be given to the laying method of duct bank, cable trench or tunnel, and combining the actual situation along the channel and the countermeasures of shrinkage to optimize the design of corner well and joint well.

When the online monitoring equipment is supplied by the traditional current transformer (CT), it is easy to be affected by the large-scale fluctuation of the transmission line current. This fluctuation will not only lead to insufficient CT power when the current of the transmission line is small, but also make the CT magnetic core saturated at high current. In order to solve the above problems, a method for realizing the energy harvesting transformer based on double-winding control is proposed in this paper. One set of coils is connected to the load side, and the other set of coils is connected to the impedance conversion circuit for reactive power adjustment. According to the magnitude of the transmission line current, the CT output impedance is controlled to work in different modes to realize the dynamic adjustment from capacitive to inductive. So as that the CT maintains a stable output voltage when the transmission line current varies in a large range. Due to the decoupling of the two coil circuits, the control of the impedance adjustment is simple. The double-winding CT is carried out through simulation. The effectiveness of the proposed scheme is verified by simulation results.

A multi-element wide gain resonant converter with trap function is proposed in this paper. Compared with the conventional LLC converter, the converter proposed in this paper can maintain the output voltage stable in a wider input voltage range. Besides, the third harmonic is used to deliver power, improving efficiency of the converter. The operating principle, voltage gain characteristics and impedance characteristics of the converter is described and analyzed in detail, and the main circuit parameters is designed in the paper. The simulation results demonstrated that the wide voltage gain can be realized by the proposed converter. Meanwhile ZVS for the primary side switches and ZCS for the secondary side switches can be achieved, and great soft-start performance can be displayed.

Large number of power electronic devices will increase the volume of multilevel inverter and increase the probability of failure; on the other hand, more redundant switching states can be provided to improve the fault tolerance of the inverter. Reduced Device Count Multilevel Inverters (RDC-MLIs) have tried to minimize the number of power electronic devices, but failed to take into account the fault tolerance of the inverter. A novel multilevel inverter topology and its hysteresis SVPWM fault-tolerant control strategy are proposed. This method not only realizes the multilevel output of the inverter, but also realizes effective fault-tolerant control for single-switch open-circuit fault and large-number double-switch open-circuit fault of the system without reducing or slightly reducing the output performance of the system. It ensures the direct switching of the driving signal to the variable structure unit, and abandons the main switching device and backup switching device operating in the inverter, which not only reduces the difficulty of implementation, but also has high stability. Through simulation and experimental results, the reliability of the topology and fault-tolerant control strategy is effectively verified.

With the increasing requirements for power system stability and the rapid development of new energy sources, demand response plays an important role in ensuring the stable operation of power systems. Commercial buildings, as an important part of demand response, can be divided into traditional buildings and intelligent buildings. Traditional buildings mainly rely on manual operation and regular maintenance to meet the needs of users, while intelligent buildings realize the optimization and monitoring of environment, energy and safety through automated systems and intelligent equipment, and automatically meet demand response based on advanced automation control technology. This paper constructs an evolutionary game model of demand response with two types of commercial buildings under the load integrator: intelligent buildings and traditional buildings as the main body; describes the difference between the two types of buildings participating in demand response; and draws the following conclusions through the analysis of the stability of the equilibrium point of the evolutionary game model: intelligent buildings will tend to participate in demand response, while traditional buildings will tend not to participate in demand response. In order to meet the requirements of demand response, commercial buildings will continue to transform into intelligent buildings.

The safe and stable operation of the new power system is facing serious challenges. The establishment and improvement of demand response incentive mechanism is one of the important ways to balance the system. Firstly, the classification of power demand response and the benefits of implementing demand response are summarized. Secondly, the paper summarizes the theoretical achievements of power demand response mechanism construction from different market backgrounds and market subjects. Thirdly, based on the experience of overseas power demand response implementation, the investigation explores the status quo and development path of domestic demand response implementation; Finally, the paper summarizes the challenges faced by Chinese demand response market mechanism, and puts forward the prospect of the development of Chinese demand response market mechanism construction.

In order to ensure the reliable work of UPS equipment with long-term and stable work requirements. Among the many control methods of multi-level inverters, this paper chooses Model Predictive Control (MPC) method to study. MPC method has unique rolling optimization ability and high dynamic response ability, which can ensure that the inverter is in a high-quality working state for a long time. When the fault of the switch tube is detected, the fast fault-tolerant control is carried out by changing the reference current and switching the voltage vector participating in the rolling optimization, so as to ensure that the output current of such equipment is not distorted and maintain the safe operation of the equipment and its load.

The quasi-power-frequency sequence oscillation is a new type of oscillation issue observed in practical renewable energy integrated power systems via MMC-HVDC in recent years. In this paper, characteristics of quasi-power-frequency oscillations in DFIG wind farms integrated power systems via MMC-HVDC are studied. Frist, state-space model of the system is established. Then impact of control parameters on the quasi-power-frequency oscillation is analyzed based on the root locus method. Finally, effectiveness of conclusions drawn based on the linearized model is verified via non-linear simulations. It is found that this new type of oscillation is mainly relative with the dynamics of phase lock loop of the DFIG, current inner loop of RSC of the DFIG and AC voltage outer loop of the MMC. In addition, increase of active power outputs of the DFIGs can also decrease damping of the oscillation.

Due to the characteristics of volatility, intermittence and uncertainty of distributed photovoltaic, when large-scale distributed photovoltaic is connected to the power grid, it will cause photovoltaic power curtailed. Therefore, a multi-level consumption strategy for access to distributed photovoltaic distribution network is proposed. Firstly, this paper studies the topology of a new energy router, and proposes a new AC/DC hybrid distribution network architecture based on it. Then, according to the operation characteristics of AC/DC hybrid distribution network, the coordinated control strategy of four-level consumption including bus consumption, cross-bus consumption, cross-area consumption and energy return to the grid is studied in detail, which avoids the direct injection of photovoltaic power into the distribution network and reduces the energy exchange between the station areas and the grid. Finally, in the Matlab/Simulink simulation environment, the distributed photovoltaic four-level consumption is simulated and verified, and the results prove the effectiveness of the proposed multi-level consumption strategy.

In the context of the new electric power system, the large-scale access of renewable energy source and power electronic devices has led to an increase of harmonic components in the main grid. High-voltage circuit breakers, as crucial switching devices in the power system, will be influenced during their breaking performance under harmonic conditions. Therefore, investigating the breaking performance of high-voltage circuit breakers under harmonic conditions is essential for preventing the serious consequences that could arise from breaking failures. In this study, a harmonic breaking experimental platform was constructed using a synthetic circuit to simulate actual operating conditions of the power system. Through conducting breaking experiments under both fundamental frequency conditions and harmonic conditions, the influence of harmonics on arc energy and the erosion condition of contacts in high-voltage circuit breakers was analyzed. The experimental results indicate that, in comparison to fundamental frequency currents, harmonic currents cause significant fluctuations in arc voltage during the breaker interruption process. When the arcing time is same, the arc energy of harmonic conditions is higher, leading to more severe erosion of the contacts.

For the sensorless control method of traditional sliding mode observer, the high frequency harmonic content in the fundamental wave of Counter-electromotive force is high, the dither is serious, and The error of rotor position estimation is relatively large. In this paper, a sensorless control method of PMSM with adaptive sliding mode observer is proposed. Firstly, the adaptive rate of Counter-electromotive force is constructed, and the adaptive rate satisfies the stability of Lyapunov function. The adaptive sliding mode observer is constructed, which can rapidly reduce the observation error of Counter-electromotive force. In the rotor position estimation process, a phase-locked loop method is adopted, and a rotation impact elimination link is added to the traditional phase-locked loop, the effect of speed change is eliminated and the observation accuracy of sliding mode observer is improved. Finally, set up in Matlab/simulink simulation model. The results show this approach can effectively suppress sliding mode dither, reduce high-frequency harmonics in Counter-electromotive force, the high frequency harmonics in the Counter-electromotive force are reduced and the precision of rotor position observation is to improve.

Hydrogen production from wind power is an important method to solve the problem of wind abandonment and improve the utilization rate of wind power. However, the “source” turbulence caused by unstable wind speed and the “load” turbulence caused by sudden load change will adversely affect the stable operation of power-to-hydrogen system and the grid connection stability of wind farm. To solve this problem, a synergistic control strategy between supercapacitor and power-to-hydrogen system is proposed. The strategy is based on the Ensemble empirical mode decomposition algorithm. By making the supercapacitor stabilize the high-frequency component in the turbulence of “source-load”, the stability of power-to-hydrogen system is improved, and an optimal allocation method of supercapacitor capacity suitable for the control strategy is proposed. Finally, the effectiveness of the strategy is verified by Simulink simulation.

Magnetic Resonance Imaging (MRI) is currently one of the most promising medical imaging techniques. At ultra-high static magnetic field strength (≥7 T), MRI achieves improved signal-to-noise ratio and enhanced image quality to resolve fine anatomical structures at submillimeter scale. Nevertheless, at these high field strengths, the wavelength of the MRI radiofrequency (RF) field becomes smaller than the human body dimensions. As a result, conventional birdcage transmits resonators exhibit inherent standing wave effects, leading to RF field inhomogeneity and higher specific absorption rate (SAR). Previous research has demonstrated that employing travelling-wave excitation through an embedded waveguide can effectively address the issues of RF field inhomogeneity and high SAR associated with traditional birdcage coils in ultra-high field MRI. However, travelling-wave excitation suffers from low energy transmission efficiency when exciting the waveguide, and there is a lack of clear design principles for feed antenna. This paper explores the correlation between the antenna gain and proton spin excitation efficiency through exciting waveguide in ultra-high field travelling-wave MRI. Novel designs for the feed antenna are proposed as well. It suggests additional space of improvement in travelling-wave excitation at ultra-high field MRI.

Planar microwave sensors, known for their low cost and simple fabrication, are widely employed for characterizing the permittivity of materials. In this study, we propose two high-sensitivity sensors for planar material permittivity characterization based on improved single-ring complementary split-ring resonator (CSRR) structures. The first sensor incorporates a spiral-shaped slot structure (SS-SS), while the second sensor employs an interdigital-capacitor-shaped slot structure (IDCS-SS). Each sensor designs significantly enhance the electric field in the sensing region, maximizing the interaction between the tested sample and the sensor’s coupling field at the resonance frequency. The proposed sensors, along with the traditional circular dual-ring complementary split ring resonator (DR-CSRR), were loaded with identical material under test (MUT) spanning a permittivity range of 1 to 10. The sensitivity of the sensors was quantitatively compared by experimentally measuring the resonance frequency along with the variation rate of permittivity. The results indicate that compared to the traditional circular DR-CSRR sensor, both proposed sensor structures exhibit higher sensitivity, with the IDCS-SS sensor achieving the greatest improvement at 1.57 times.

A simplified space vector modulation (SVM) is proposed in order to realize that the SVM algorithm can be applied in modular multilevel converters (MMC) with more than five levels. First, the α and β axes of the tradition coordinates αβ are stretched so that the space vectors lie on integer grids. Second, the adjacent space vectors are used to construct a square with offside length 2. Next, the region in the square where the reference vector is located is quickly located. Then, a reference vector is synthesized using three space vectors of the region based on the principle of volt-second equilibrium. Finally, a three-phase MMC system simulation model is built using Matlab/Simulink, and the effectiveness of the algorithm is verified through simulation comparison.

As the demand for energy increases, the integrated energy system (IES) has developed rapidly. The IES includes various types of energy, which can help to realize the mutual coupling and transformation of electricity, gas, wind and other energy. The existing basic theory cannot adapt to the energy coupling relationship in the energy system anymore, so other aspects are needed to reveal the principle of energy transmission and transformation in the IES. This paper has studied the operation of the IES based on the heating system, and has found that compared with the energy system based on the energy network theory, the accuracy of the prediction of the electricity consumption for the selected industrial park heating was higher, more than 97%, while the accuracy of the prediction of the heating electricity consumption of the system based on the energy network theory was less than 94%. Meanwhile, based on the heating system, the utilization rate of all kinds of energy could also be improved, and the utilization rate of all kinds of energy was above 91%. The IES based on heating system can help to reduce the cost of energy system operation, improve the speed break of operation and increase the conversion rate of various types of energy, which can meet the needs of the times for resources, and also help to protect the environment. Therefore, it is meaningful to study the operation of IES based on heating systems in this paper.

Configuring energy storage system (ESS) in photovoltaic (PV) DC collection systems can suppress PV fluctuations. For PV DC collection systems, this article considers the system output power characteristics and configuration ESS costs, and designs a double-layer solution model for multi-objective optimization. The overall optimization objective is to minimize the system configuration ESS cost, and the outer layer determines the configuration power and capacity of the ESS. Particle swarm optimization algorithm is used to solve the problem; The inner layer determines the optimal operating strategy for energy storage, using yalmip and cplex for optimization solution. The example analysis shows that the proposed model can improve the output power characteristics and economic performance of the PV DC collection system. The model is feasible and effective, and it also demonstrates that the model can provide theoretical support for the rationality of ESS configuration in the PV DC collection system, which is conducive to the perfect development of the PV DC collection system.

The microsecond pulse supply based on flyback has the advantages of a simple circuit structure, few power components, a simple drive circuit, and convenient modular expansion. It has a wide application prospect in applying dielectric barrier discharge (DBD) plasma drive. However, the output of this type of microsecond pulse supply is a pulse current source, which, by Cload under DBD equivalent capacitive load conditions, charges the load capacitor, and generates a high voltage pulse voltage Upulse, generating discharge plasma. The smaller the load capacitance, the higher the amplitude of the pulse voltage generated. In practical engineering applications, inevitably, the load electrode connection is not strong. Still, it is fatal for the microsecond pulse current source, which will cause the output pulse voltage amplitude to be too high damaging the power supply and causing human contact safety problems. This paper proposed a resistor-capacitor-diode (RCD) branch, in which the voltage amplitude of the output terminal can be effectively limited by reasonably designing the voltage on the RCD energy storage capacitor Cs and the amplitude of the pulse output voltage Upulse by controlling the secondary opening mode of diode Ds. Finally, the effectiveness of the proposed method is verified by simulation experiments.

Pulse electric current sintering is a new powder material synthesis technology. Due to the limited output accuracy of the current source, it is difficult to precisely control the amount of charge that passes through the sample and the mold, to precisely adjust the temperature rise rate of the target sample. Based on the topology of the linear current source, a high-precision current source with lumped current outer loop and the distributed current inner loop is designed in this paper, which consists of two parts: the distributed current inner loop power stage unit and the current outer loop feedback calibration unit. The working principle and characteristic parameters of the double closed loop current source are analyzed through the circuit structure. The influence of the power transistor on the output current accuracy is analyzed through verification experiments, and it is proved that the current source can output extremely high current accuracy, achieve a static error of mA level, and realize rapid temperature rise during sintering.

Due to the dominant resistive component in distribution lines, the voltage upper and lower limits may occur in the same scenario. The voltage upper limit is caused by daytime photovoltaic power injection, while the voltage lower limit is caused by nighttime line voltage drop. Load tap changer (LTC) voltage regulation and dynamic reactive power compensation voltage regulation devices have certain limitations. A method using a Rotary Voltage Regulator (RVR) is proposed, which injects a constant amplitude and continuously adjustable phase voltage phasor into the line by controlling the relative angle of the rotor. Regarding the four-quadrant bidirectional voltage regulation characteristics of RVR, the method to improve the power factor under the premise of voltage regulation is studied. Furthermore, the overshoot problem caused by the mechanical structure during the voltage regulation process is analyzed, and a variable speed control scheme for RVR is designed. Finally, a 380 V/40 kVA RVR prototype is developed, and experimental results show that RVR can effectively improve the power factor at the access point while satisfying the voltage regulation requirements, thus verifying the effectiveness and correctness of the proposed control strategy.

Although modular multilevel converters (MMCs) are more and more widely used, low frequency ripple voltage appears in sub-module (SM) capacitors due to the operating mode, and the fundamental frequency and double frequency are the main ones. Based on the split-capacitor sub-module (SC-SM) structure, an easy double closed loop active power decoupling control strategy is proposed in this paper. Firstly, the ripple power of MMC arm is deeply analyzed, and the operation principle of split-capacitor is introduced accordingly. Then, a mathematical model based on MMC split-capacitor is established in detail. Finally, the control strategy of voltage outer loop and current inner loop is proposed, and the AC and DC voltage decoupling is realized. The effectiveness and accuracy of the control scheme are verified by simulation experiments. The experiment results show that the voltage ripple of the split-capacitor sub-module is well suppressed in the steady state, and the voltage ripple is reduced to 3%.

With the widespread application of Distributed Generation (DG) in new energy power systems, accurate prediction of its power output has become a key issue. To address this problem, this study proposes a short-term power interval forecasting method for distributed power generation in distribution networks based on Quantile Random Forests. Initially, in-depth processing was performed on historical photovoltaic and wind power active power data, as well as meteorological data. This included the imputation of missing values via KNN, the handling of outliers, and normalization, as well as the selection of major influencing factors on the output of distributed power through correlation analysis. Subsequently, we employed advanced technologies such as quantile regression, random forests, and confidence intervals to construct a Quantile Random Forest interval forecasting model tailored to distributed power in distribution networks. After the model’s construction, adjustments were made to the model parameters, followed by cross-validation and further debugging and optimization. Lastly, the key meteorological information for future prediction was input into the optimized model for forecasting. The forecasting method in this study takes full advantage of the Quantile Random Forest’s strengths in dealing with non-linear, high-dimensional data, and handling missing data, enhancing prediction accuracy and reducing prediction bias, providing significant guidance for actual network operation and dispatching. Future research will continue to deepen the understanding and application of the Quantile Random Forest model in hopes of improving forecasting results and optimizing grid operation.

In the process of demand response, in order to manage resources in the load side better and solve the problems of large amount of data, unclear data characteristics and many invalid data, the load aggregator proposed a load forecasting model based on data mining and improved stacking ensemble learning. Firstly, analyze the energy consumption behavior of loads agented by load aggregators, and models for various loads participating in demand response are established; Then, the data processing feature engineering based on data mining model is established to extract the features of the original data and form the load forecasting feature data set; Finally, through improving stacking ensemble learning model, all kinds of loads under the load aggregator are predicted. To verify the effectiveness of the model, the article conducts experiments using real load data from a certain location. And compare it with other algorithms. The experiment shows that the model proposed in the article improves the prediction speed and accuracy, providing a reliable basis for load aggregators to participate in the demand response market.

In order to improve the accuracy of short-term load forecasting, a hybrid forecasting model based on variational mode decomposition (VMD), fuzzy logic and gated recurrent unit (GRU) is proposed. Firstly, the original load sequence is decomposed into several modal components by VMD algorithm, then the decomposed modal components are combined with the fuzzy processed meteorological information, and then the combined data are inputted into the GRU model for prediction, and finally the prediction results of each modal component are superimposed to obtain the final load prediction results. Through simulation experiments and comparison with other models (SVR, LSTM, GRU, VMD-FGRU), the hybrid model proposed in this paper has better prediction accuracy.

With the proposal of the “double carbon” goal, the proportion of distributed generation in the power grid is gradually increasing, distribution network faults will lead to voltage sags, which may make the distributed generation into the low voltage ride-through process or even off-grid, and sensitive loads to work abnormally, affecting the normal operation of the power grid. This paper takes a typical radial distribution network as an example and analyzes the depth of voltage sags at new energy-type equipment points of common coupling (PCC) in different grounding methods and at different locations where various faults with transition resistance occur. Theoretical analysis and PSCAD/EMTDC simulation analysis results show that the closer the fault is to the PCC, the deeper the positive sequence voltage sag at the PCC, and the lowest positive sequence voltage is lower than 0.2 pu in a three-phase short circuit, and the obtained conclusions provide some guidance for the fault voltage compensation strategy such as Dynamic Voltage Restorer (DVR).

Formed-parallel coil is a new stator coil type of flat-wire motor. It is designed to reduce the eddy current loss in the stator coil and decrease the difficulty of coil production. In the experiments, it can only detect the total current of each stator coil instead of the current distribution of each strand. Aiming to solve the problem, this paper proposes a strand current measuring method based on Hall sensors without destroying the coil structure. The end leakage magnetic field (ELMF) and strand current are analyzed by finite element solution (FEM). The relationship between the strand currents, ELMF and Hall output signal is derived. The coil strand current test platform is built and the experimental verification is carried out by a 15 kW flat-wire motor. The result shows that the current measuring method can measure the current distribution in the strands accurately. It provides an experimental evaluation basis for analyzing the reasonableness of the strand current distribution and the design of the formed-parallel coil.

In recent years, after the voltage at the grid-connected point drops due to the failure of the wind turbine, there are frequent cascading failures caused by the sudden rise of voltage due to excessive reactive power compensation. In order to enable wind turbines to provide suitable power support in case of grid failure. The wind turbines connected to the grid are required to have LVRT ability and HVRT ability according to the national standard. In this paper, a low-high voltage interlocking FRT strategy for reactive power input control of RSC and GSC by a DFIG is used. The limit values of reactive currents issued by RSC and GSC when chain faults occur and the allocation principles are discussed. It is verified through simulation that the continuous low and high voltage ride-through ability of DFIG during operation can be effectively ensured, which in turn ensures the stable operation of DFIG.

Due to the increasingly fierce competition in science, technology and economy, optimization algorithms play a crucial role in the design of electromagnetic devices. At present, optimization methods based on evolutionary algorithms are widely used in social development, but many algorithms still reflect the problems of insufficient global search ability, easy to fall into local optimal solutions, and insufficient diversity of solutions when dealing with objective functions with multi-modal landscape, discontinuities and other characteristics. A new hybrid multi-objective optimization algorithm is proposed to solve the above problem, which is based on Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-objective Grey Wolf Optimizer (MOGWO) algorithm. In this new optimization algorithm, NSGA-II is chosen as the core, and leader decision-making mechanism of MOGWO and other techniques are adopted, which improves the convergence performance of the hybrid algorithm, and enhances the diversity of the Pareto solutions. Performance testing of the new hybrid algorithm for convergence and diversity, and it is applied to the optimal design problem of electromagnetic devices. The results obtained demonstrate that the algorithm has correctness and effectiveness.

TRIZ theory of invention, as a theory of invention and innovation, has been widely used in various fields. In this paper, the contradiction matrix of TRIZ theory is combined with power electronic topologies to systematically illustrate the construction laws and methods of new topologies. Taking the power electron conversion topology of DC-DC circuit as an example, the construction principles of several common topologies are analyzed, and the feasibility of the construction method is verified. In addition, combined with TRIZ theory to guide the regularity of the new topology of power electronics, a new type of soft switching high-gain enhanced converter is proposed, which provides a new idea for the construction of power electronic circuits with better performance.

Under the background of green development, China actively promotes environmental protection policies, and the pressure of transformation of highly polluting industries increases accordingly. This paper chooses the thermal power industry, which consumes relatively more coal and pollutes relatively more, as the research object, analyzes listed companies from the perspective of environmental protection administrative penalties, and proposes the environmental protection administrative penalties constraint effect and the pollution externalization effect, which are the two reaction pathways of companies when facing the possibility of pollution. By analyzing the financial statements of 25 thermal power companies and the number of environmental administrative penalties during the period from 2013 to 2020, it is found that the net profits of listed companies in the thermal power industry that are subject to more environmental administrative penalties are more sensitive to the number of environmental administrative penalties, which suggests that environmental administrative penalties play a role in restraining the polluting behaviors of companies. This means that in the thermal power industry, the administrative penalty constraint effect is greater than the pollution externalization effect, and the supervision of our environmental protection department is appropriate and the guiding role is obvious.

In order to deeply understand the interactive process of various subjects in the park's integrated energy system, effectively guide the demand-side load optimization and promote energy low-carbon, this paper puts forward a master-slave game optimization scheduling model of the park's integrated energy system based on ladder demand response, with the park operator as the leader and the user aggregator as the follower. First of all, a master-slave game structure with park operators and user aggregators as the main body is constructed, and a stepped demand response incentive mechanism is established to guide the energy use behavior of the user side; Secondly, based on the Stackelberg game theory and taking into account the carbon trading mechanism, with the goal of maximizing the comprehensive income of the park operators and the consumer surplus of the user aggregators, the optimal scheduling model of the comprehensive energy system considering the master-slave game of the park operators and the user aggregators is constructed; Finally, the theoretical research is analyzed and demonstrated through a numerical example, and the results show that the game interaction model proposed in this paper can effectively improve the benefits of the principal and subordinate parties, and reduce the carbon emission level of the system.

As power electronic devices move towards higher power density, miniaturization, and integration, traditional cooling methods are no longer sufficient to meet their cooling needs. The Power Equipment New Technology Laboratory of the Institute of Electrical Engineering, Chinese Academy of Sciences (CAS), has proposed a new surface-mounted evaporative cooling technology. However, existing research on the heat transfer characteristics of surface-mounted evaporative cooling systems still has significant shortcomings. To address the real-time visualization issue of the operating state of the liquid box in the surface-mounted evaporative cooling system, this paper applies Electrical Capacitance Tomography (ECT) technology to detect the capacitance signal of the liquid box during operation. In response to the differences between the liquid box structure and traditional pipelines, two sets of sensors are designed for comparison.To mitigate the ill-posedness of ECT, a pixel interpolation method is employed to improve the image reconstruction algorithm. Simulation results indicate that compared to traditional algorithms, the relative error of the pixel interpolation method mostly decreases by more than 0.1. The image correlation coefficient increases by more than 0.05, significantly enhancing image quality. Compared to traditional two-phase flow detection methods, the approach presented in this paper exhibits higher accuracy and robustness.

The construction of smart grid transmission projects and UHV projects plays an important role in promoting the formation of inter-provincial spatial connectivity and allocation and the optimal allocation of energy resources on a large scale in provinces and regions. Based on relevant data, this paper first sorts out the construction and development history of China's regional power grid and UHV transmission projects, and clarifies the connection of inter-provincial transmission projects and the characteristics of cross-provincial and cross-regional power transmission in recent years. Secondly, combined with the characteristics of the transmission and configuration of renewable energy power in transmission projects in China, the spatial connection weight matrix of power grid projects in different years is constructed, and the connectivity characteristics of transmission projects in the spatial dimension are compared and studied, and the development and change law of transmission power grid projects in China is analyzed, so as to provide reference for the construction of transmission projects.

Rapid decarburization of energy sector is critical in the transition to global net zero, and building Energy Internet (EI) relies on a new technology revolution. In this paper, a model for evaluating science and technology (S&T) innovation capability of EI firms is introduced, in which Analytic Hierarchy Process (AHP) is used to determine the weight of each index and Fuzzy Comprehensive Evaluation (FCE) is adopted to obtain rational assessment results. Qualitative indicators and quantitative indicators, process indicators and outcome indicators, common features and individual characteristics, are effectively taken into account in the assessment process by the full combination and effective application of AHP and FCE. Finally, seven EI firms were investigated as case studies, and the viability of the suggested model are successfully validated.

Aiming at the stochasticity of PV output power, and considering the influence of node critical inertia when system disturbance occurs, in this paper, a calculation method of PV power station siting capacity taking into account the node inertia constraints is proposed. Firstly, the primary embedding location of the PV plant is confirmed based on the results of the node critical inertia calculation when the disturbance occurs; Then, taking the minimum voltage deviation, the maximum total capacity of accessed PV and the minimum network loss as the planning objectives, the node voltage qualification rate as the main constraints to construct the calculation model. At the same time, the hierarchical analysis method is used to establish the optimal total objective function for the coordination of the three planning objectives and the particle swarm optimization (PSO) is used to solve the model. Taking the IEEE39 system as an example for simulation analysis, the results show that the network node voltage deviation and reduced by 26.9%, the total amount of renewable energy access is 707 MW and the node voltage qualification rate meets the planning requirements.

In order to solve the security risks between different power grids, it is necessary to use flexible interconnection devices to interconnect with each other to improve the security and reliability. With the development of dual-high power grids, the optimization of flexible DC interconnection topology should not only consider the location and capacity of traditional zonal interconnection devices, but also take into account the influence of node distributed inertia. In this paper, the first selection is carried out through the node-distributed inertia. Secondly, the active demand of the receiving grid is determined based on the change of the total supply capacity after the N-1 fault and the reactive demand is obtained through the sensitivity method, so as to put forward the scope of determining the capacity and obtain the optimal results of the site. Finally, the methodology is verified by the example, and the safety calibration is carried out for the obtained results. After the input of the flexible DC interconnection device, the power supply pressure of heavy partition can be alleviated, the power support can be carried out when the fault occurs, and the voltage of the partition grid can be stabilized.

Aiming at the frequency distribution of different nodes of the new energy power system when perturbation occurs, the node computational inertia index is defined to characterize the ability of a single node in the grid to resist the system frequency change after perturbation, and to quantify the inertia distribution characteristics of the system. Considering the physical structure and parameters of the power grid, the expression of the node calculation inertia of the multi-machine system is deduced, and an example simulation is carried out through the IEEE39 node system, which verifies the correctness of the node calculation inertia, with an average error of 8.7%, and the lowest can reach 0.1%, and the simulation results show that the proposed node calculation inertia can accurately characterize the inertia distribution of the new energy power system, and the final calculation result proposes a new node inertia index for the multi-machine system based on the node inertia. Finally, a critical inertia compensation calculation method for multi-machine system is proposed based on the nodal inertia calculation results, and the results show that the proposed method can improve the level of nodal inertia very well.

With the increasing proportion of renewable energy in the power system, the increasing uncertainty on the generation side, the increasing demand for system reserve capacity, and the increasing abundance of reserve auxiliary service market players, the research on reserve capacity and reserve auxiliary service market trading rules is a hot topic at present. This paper takes Northwest China and East China as examples, summarizes the trading rules of reserve auxiliary service market in each region, analyzes the similarities and differences of the rules in each region, and researches the market signals released by the rules, expecting that it will help to formulate and improve the trading rules of reserve auxiliary service market in other regions.

With the continuous development of the electricity market and the intensification of competition, the price competition among electricity suppliers is becoming increasingly intense. This kind of competition not only significantly impacts the survival and development of power suppliers but also directly affects the interests of power users and the stability of the social economy. Therefore, understanding the price competition mechanism of the electricity market and predicting the price change trend is of great significance to the healthy development of the electricity market. This study uses the zero-sum game model in game theory to simulate the price competition between two electricity sellers in the electricity market. In our model, the response strategies of electricity retailers in the early and late stages significantly impact their final economic benefits. In addition, the demand pattern of electricity buyers and the response strategies of electricity sellers have an essential impact on the bidding results. This study provides a new perspective for understanding the price competition in the electricity market and provides valuable enlightenment for regulating and managing the electricity market.

The overvoltage and reactive power imbalance issues brought on by the large charging reactive power of transmission submarine cables are becoming more and more noticeable as the offshore wind farm alternating current (AC) transmission system moves toward long distance, high voltage, and large capacity. This paper presents a reactive power compensation approach that takes into account the system’s steady-state reactive power requirements as well as power frequency overvoltage with the goal to increase the safety and reliability of system operation. Firstly, the offshore wind power high-voltage AC transmission system simulation model is built in PSCAD/EMTDC. Secondly, in order to configure the capability of the fixed high-voltage shunt reactors placed in the onshore control center, different kinds of power frequency overvoltage are investigated and compared. Then, the steady-state reactive power demands are analyzed, the compensation capacity and switching stages of the adjustable shunt reactor are determined with the goal of no reactive power flow at the point of common coupling (PCC), and a reasonable control strategy is formulated. Finally, the simulation verification shows that the reactive power compensation method can limit power frequency overvoltage to the specified range and compensate the steady-state reactive power demand in real time.

In order to examine the impact of downhole electromagnetic energy barriers on the energy utilization efficiency of shale spectral resonance devices, a simulation analysis of the sealing effect of these barriers is performed. Using COMSOL Multiphysics software along with the principles of elastic wave propagation and nonlinear finite element algorithm, the propagation process of shock waves in the presence of electromagnetic energy barriers in downhole environments is analyzed. The simulation results demonstrate that following pulse discharge from the discharge unit of the shale spectral resonance device, the resulting shock waves propagate through the water and casing. By comparing the pressure of the shock waves detected at the specific point on the inner wall of the casing with and without the downhole electromagnetic energy barrier, the effectiveness of the barrier in sealing the shock waves is confirmed. Consequently, the energy utilization efficiency of the shale spectral resonance device is improved by 46.8%. This analysis provides a theoretical foundation for the practical implementation of downhole electromagnetic energy barriers in unconventional oil and gas production operations.

Solar energy is a potential renewable energy that is very important for the increasing energy needs of people living in modern life and contributing to reducing environmental pollution in energy production. To contribute to solving the above problem, existing fossil fuel power plants replaced by solar PV power and increasing the capacity of solar energy to meet the growing energy demand is a key role which can reduce climate change problem and reduce electricity production costs. However, the potential of Solar PV is closely related to the geographical location installed because the energy emitted from Solar PV depends on the amount of sunlight received, so the solar PV power output has variations. Therefore, energy storage is significant in power systems that use a large portion of solar energy in the grid. When the power supply exceeds the energy demand is charged into the storage and discharged during periods of power demand exceeding the power supply. It means that energy storage is a tool to balance the power system with unpredictability and fluctuations in renewable energy resources. The energy storage system is significant, but a high-capacity energy storage system has a high cost, so the electrical manufacturing sector can benefit from technologies that reduce energy storage. This paper presents the energy storage optimization technology to achieve solar PV penetration into the gride base on the ramping of power source generators.

This research tackles the issue of insufficient accuracy in short-term electricity price forecasting. The novel approach combines a dual-stage signal decomposition technique using CEEMDAN and VMD, alongside a bidirectional gated cyclic unit network. The historical electricity price dataset is initially subjected to decomposition and entropy analysis. Subsequently, a KNN-driven clustering process partitions the data into distinct frequency-based signals. These separated signals then undergo further decomposition through VMD, enhancing the capture of intricate patterns. The enriched features are then channeled into a bidirectional gated cyclic unit network to facilitate comprehensive pattern learning. Rigorously evaluated using real-world US electricity data, the model exhibits a notable enhancement in predictive accuracy, showcasing its potential for practical application.

The energy of the cable status monitoring system comes from the self-powered coil of system sensor, and the energy harvesting efficiency of this coil will directly determine the operation of cable status monitoring system. Considering that the failure of traditional self-powered coil caused by uneven spatial magnetic field distribution in three core cables, this paper based on the idea of spatial electromagnetic energy conversion, and proposed a simplified calculation model for spatial magnetic field distribution in three core cables, to guide the optimization design of self-powered coil in cable sensors. Firstly, according to the structural characteristics of three core cable, a simplified calculation model of cable space magnetic field is proposed, and the magnetic field at any position in the space around the cable is solved based on the basic Electromagnetism theories such as Ampere’s Law, and then the output voltage of self-powered coil is derived; Then, based on the above model and theory, the magnetic field distribution of the three core cable and the output voltage of self-powered coil were analyzed, thereby achieving the optimization design of the self-powered coil for three core cable.

As more and more photovoltaic power generation systems are integrated into the power grid, it has brought a huge test to the stability of the power grid. For the purpose of reduce adverse effects of photovoltaic grid-connected on the grid, the paper proposes a novel quasi-Z-source inverter grid-connected structure on the strength of Virtual Synchronous Generator (VSG). The structure can be divided into two parts. The first part is the control part based on virtual synchronous generator technology. The second part is the boost part based on the novel quasi-Z-source fabric. That proposal of this structure not only simplifies the structure of the traditional two-stage step-up inverter, but also significantly improves the step-up capability. At the same time, it also solves the problem of low inertia and non-damping characteristics the grid-connected photovoltaic power generation system. The combination of the two improves the dynamic performance and stability of the system. Finally, through analysis of this results that the simulation experiment, the feasibility is verified.

The supercapacitor can form a double cascade system with other converters. When the scheme of the other party that constitutes the cascading system with itself is unknown, it must be able to meet the cascading stability requirements. In order to achieve the corresponding stability, the input and output impedance of the supercapacitor DC-DC converter under two types of cascade conditions are analyzed, the influence of different control parameters on the impedance is analyzed, and the design rules related to the cascade stability are proposed. Due to the influence of magnetic core saturation, the filter inductance changes and the circuit parameters change, so the variable parameter control scheme is adopted for the ultracapacitor DC-DC converter to meet the control needs. After the corresponding analysis, simulation is carried out and experimental results are given to prove the correctness of the analysis.

Compared to conventional power cables, high-temperature superconducting cables have advantages such as high current-carrying capacity, low losses, compact structure, and no electromagnetic radiation. The application of high-temperature superconducting cables is of great significance for the future power system in terms of high-power, long-distance transmission of electrical energy [1], as well as energy saving and emissions reduction. In order to better understand and use superconducting cable in engineering practice, this paper focuses on the electromagnetic characteristics of superconducting cables. Firstly, the effects of temperature and magnetic field on the critical current of high-temperature superconducting tapes are analyzed, and an anisotropic model is proposed. Then, due to the limitations of traditional 2D model in accuracy and traditional 3D model in simplicity, a 2D finite element simulation modeling method applicable to the spiral winding structure of superconducting cables is presented, and this method is used to analyze the electromagnetic characteristics of superconducting cables.

Under the strategic goal of carbon peaking and carbon neutrality, it is urgent to build a new power system characterized by clean and low carbon, safe and controllable, flexible and efficient, intelligent and friendly, open and interactive. As the key equipment of flexible DC transmission, voltage source converter valve plays a very important role in the smooth operation of flexible DC transmission system. At present, domestic research mainly focuses on theory and engineering application, and there is little research on RTDS verification device. The valve control simulation verification device proposed and developed in this paper can simulate the basic functions of grid-connected operation and sequential control of the actual VSC-HVDC project on the RTDS system by combining the secondary complete sets of equipment such as main control device, coordinated control unit and monitoring system. At the same time, it has the ability of fault diagnosis and timely reporting and the ability of module voltage self-balancing, which can meet the hardware-in-the-loop simulation requirements of high-voltage modular multilevel converter. It is a key component of the verification platform required for dynamic characteristic analysis, fault feature extraction and engineering application of high-voltage VSC-HVDC system.

A high-power radio-frequency (RF) negative ion source is a key component of the high-energy neutral beam injection (NBI) for the magnetic confinement nuclear fusion facility, in which the driver is the place to produce the plasma using the RF induction heating. To measure the real-time RF impedance of the driver helps us to establish the relationship between the driver equivalent impedance and the plasma parameters. Because the impedance angle of the driver is close to 90° and its variation range is small during the operation of the ion source, it requires the RF impedance measuring device based on V-I detection should be of high phase accuracy. At present, the driver impedance measurement is mainly based on the indirect measurement, but this method needs to establish a complex matching network circuit model, and the calculation is complicated and lacks reliability. Thus a preliminary scheme of RF impedance measurement with high phase accuracy is proposed. For the hardware circuit, a conditioning circuit with low phase noise and high signal-to-noise ratio is designed for the RF voltage and current transformers, and a high-precision sampling circuit with equal intervals of time is designed. For the software design, use all-phase FFT analysis with the phase correction to extract the signal amplitude and phase information. In theory, this scheme can realize the measurement accuracy of 1% amplitude and 0.1° phase at 1 MHz.

With the proposal of the Carbon-neutral Target and the continuous promotion of the construction of new power systems, the degree of China's power market-oriented reform has been deepening. On the one hand, the number of participating subjects in the user-side power market has increased, and the variety of transactions has been enriched, which puts forward higher requirements for the operation efficiency of power trading centers and other aspects; on the other hand, power trading institutions, as the operators, builders and managers of power trading, should develop in synergy with dispatch centers and load management centers to strengthen the information interactions and business dealings, and at present, the dispatch centers and load management centers have already realized the operation of multi-level organization system. Therefore, this paper firstly analyzes the challenges faced by the trading center under the new power system, and explores the current organizational system of the power trading center, and finally puts forward the innovations of multi-level and grid based on the original organizational structure and management level of power trading centers, which will support the efficient and stable operation of the future market of multi-market subjects and multi-transaction varieties.

The disorderly charging tactics of large-scale electric vehicle (EV) will lead to the increase of peak-valley load difference of the power grid and destroy the stability of the power system. In order to solve this problem, considering the peak adjustment demand of the grid side and the different demands of the users on the charging amount and charging cost, this paper proposes a hierarchical optimization scheduling method based on the dynamic TOU time segment model. This method updates the load curve according to the load information of each EV when it is connected to the grid. Meanwhile, the dynamic time-of-use electricity price model proposed in this paper is used to dynamically update the peak-valley electricity price of the EV. Among them, the upper layer model takes the minimum variance of the total load of the grid as the objective function, and the lower layer model takes the minimum deviation of the agent scheduling plan, the maximum amount of charging and the minimum cost of charging as the objective function, and adopts the improved PSO algorithm to optimize the charging (discharging) tactics of each EV. Finally, the simulation analysis is carried out with a concrete example. The results show that this method can effectively reduce the peak-valley difference of load demand curve on the premise of ensuring the travel demand and economic benefits of EV owners.

The suppressor grid power supply has been developed in the neutral beam injector (NBI) for the experimental advanced superconducting tokamak (EAST). Being an important part of NBI’s power supply system, the suppressor grid power supply will deliver a high dc voltage at the suppressor grid. It mainly consists of a thyristor voltage regulator, a bridge rectifier, an LC filter, a fast switch and the control and protection circuits. Given the operation characteristics of the power supply, the corresponding requirements and specifications are described. Later on, this paper basically introduces the circuit structure, the control and protection methods and the fast switch technology. Some ratated test results and the operation results are also presented, which verified the performance of the power supply.

The control of three-phase voltage source PWM rectifiers is generally carried out in a two-phase synchronous rotating coordinate system, which can convert the three-phase quantities into DC components, making it easy to control and adjust. Through the analysis of the mathematical model, it was found that there is a coupling term of inductance L in the current inner loop of the control system, and the value of inductance L will change, affecting control performance. Under low frequency and strong disturbance conditions such as ocean currents, traditional control strategies face significant challenges. Therefore, an optimized design scheme based on a dual closed-loop three-phase voltage source PWM rectifier control strategy is proposed. The voltage outer loop uses the square of the DC output voltage as an indirect control variable to achieve fast tracking of the output voltage; The current inner loop obtains a decoupling control method for reducing order and removing the influence of inductance L by constructing a linear decoupling model. Further simulation analysis has demonstrated the feasibility and effectiveness of this control strategy optimization design scheme.

The price index of hydropower engineering plays a crucial role in cost management. Analyzing and predicting the trends of classified engineering price index using qualitative methods have limitations, as they may not be applicable to all price index. To address this issue, this study takes selected classified engineering price index in Southwest China as an example and establishes a multidimensional conditional autoregressive (CAR(n)) model based on the adjustment factor, i.e., price index. The results indicate the model demonstrates dynamic extrapolation properties with low model errors, particularly in short-term forecasting. Furthermore, the traditional approach of calculating price index through time-consuming weighted averages using adjustment factors is replaced with a new predictive method provided by this model. This model for calculating price index in specific projects or within a certain basin holds promising potential. Moreover, the determination of the forgetting factor in the model is related to many factors such as the duration of construction, price fluctuations, and economic development cycles. The selection of forgetting factor has a significant impact on the accuracy of the model, which is noted in modeling.

The construction of China's new power system has entered an important stage of comprehensive start-up and acceleration, and the investment in power grid has been expanding, and the infrastructure construction has been carried out comprehensively. Transmission line construction is an important part of power grid engineering construction, improving the mechanization rate of transmission line construction, realizing the multiple advantages of transmission line construction such as high quality, high economic efficiency and high social efficiency is an important direction of current research. This paper takes the 110 kV transmission project of Hunan Zhuzhou Longtou 220 kV substation as an example, and analyzes the mechanization rate, economic benefit and social benefit of the project based on the introduction of foundation construction, tower erection and erection of wires, and puts forward the shortcomings of the project and the direction of improvement, so as to provide effective references for the construction of similar projects in the future.

The power prediction of photovoltaic (PV) generation is an important basis for the power system to formulate power generation plans and coordinate dispatch. However, due to the randomness and intermittency of the PV generation process, there is still much room for improvement in the accuracy of PV power prediction. This paper proposes a PV power prediction method based on a mixed model of three-dimensional convolutional neural network (3DCNN) and convolutional long short-term memory network (CLSTM). The input parameters of the model are determined using the correlation coefficient method, and the accuracy of the prediction model is evaluated using three indicators: root mean square error, mean absolute error, and mean absolute percentage error. To verify the applicability and correctness of the model, the prediction method based on this mixed model is ap-plied to the output prediction of a certain PV power station in Shandong, China. The PV output power under different weather conditions with the same input sequence and under different input sequences is predicted, and the results show that the prediction effect based on the 3DCNN+CLSTM mixed model is better than that of the 3DCNN model, the CLSTM model, and the BP neural network model under both scenarios.

Industrial parks are the central units for the development and aggregation of industries, playing an important role in implementing China’s “dual-carbon” strategy. Zero-carbon industrial parks represent a new form of development for future industrial parks and how to build them has become a focus of current research. This paper provides a concise overview and future prospects of the pathways and key technologies for achieving zero-carbon industrial parks. Firstly, the concept and connotation of zero-carbon industrial parks are analyzed. Secondly, the pathways for achieving zero-carbon industrial parks are summarized by analyzing the characteristics of different types of parks. Thirdly, from the aspects of Integrated Energy System Planning, hydrogen energy storage and applications, CCUS (Carbon Capture, Utilization, and Storage), and other aspects of the key technologies needed for zero-carbon industrial parks are outlined. Finally, an analysis and outlook on the challenges faced in the construction of zero-carbon industrial parks are provided.

This paper mainly studies the influence of distributed photovoltaic system access on the voltage stability of active distribution network, and uses PSCAD to establish a simulation model of distributed photovoltaic system, and describes the control scheme of distributed photovoltaic system in detail. Subsequently, the IEEE33 node distribution network model was established, and then on the basis of the above research, the static voltage stability, permeability and short-circuit ratio indicators of the distribution network were established, and on this basis, the influence mechanism of grid-connected distributed photovoltaic on the voltage distribution of distribution network nodes and the static voltage stability index of weak nodes was obtained by using the control variable method. Finally, the voltage stability of the active distribution network is optimized by the access of the reactive power compensation device, which provides a reliable reference for the actual distribution network to connect to distributed photovoltaics.

With the increasing share of renewable energy, the two-stage robust unit commitment faces challenges such as difficult to describe the feasible probability of intraday scheduling and difficult to guarantee nonanticipativity. In order to overcome the above difficulties, based on the real-time scheduling strategy of model predictive control (MPC), which is widely used in the day, this paper proposes a multi-stage robust unit commitment method that takes into account the uncertainty of renewable energy and the nonanticipativity of scheduling decisions. The method consists of an upper-level unit commitment model, a middle-level batch scenarios generation layer, and a lower-level multi-stage intraday scheduling model based on MPC. In order to obtain the nonanticipative unit commitment results, this paper proposes a constraint set construction method that can correct the unit commitment results. By constructing and using this constraint set and combining the successive iterations of the upper, middle, and lower levels, it can be obtained that satisfies probabilistic conditions robust and nonanticipative unit commitment results. The results of the case show that, compared with the two-stage robust unit commitment model, the unit commitment method proposed in this paper has significant advantages in reducing power system operating costs and ensuring nonanticipativity.