Modelling and Simulation of Power Electronic Converter Dominated Power Systems in PowerFactory

The transition to a low-carbon society is the driving force pushing the traditional power system to increase the volume of non-synchronous technologies which mainly use power electronic converters (PEC) as an interface to the power network. Today, PEC is found in many applications ranging from generation, transmission, storage, and even active loads and protections. The variety of types, applications is almost unlimited. However, the behaviour of PEC is radically different to the typical devices used in traditional power systems, and its specificity in terms of control, overload characteristics, etc. entails an entirely different approach for modelling and simulation. This chapter presents a general review of the main concepts related to power electronic converters and their implementation in DIgSILNET PowerFactory. The chapter finalises with a discussion about the modern tendencies in power electronic applications in power systems: grid following and grid-forming converters.

Recently, several large-scale photovoltaic power plants (LS-PVPPs) have been integrated into the high-voltage grids around the globe. On the contrary to the conventional synchronous generators, static generators use voltage source converters (VSCs) as an interface device to connect into the AC network. Since the VSCs consist of power electronic switches to control their output, the response time of these resources is considerably lower compared to the synchronous generators. Consequently, the VSCs are able to react much faster to any disturbance occurred in the network. In this respect, when generation rescheduling is inevitable, LS-PVPPs seem to be more effective as they can perform the required remedial actions within a short time. The study aims to investigate the performance of the LS-PVPP in maintaining system stability as a fast-response power generation unit. In this respect, LS-PVPPs (along with their controllers) and a remedial action scheme (proposed to improve the stability status) have been implemented in DSL and DPL environment of PowerFactory, respectively. The results of the dynamic simulations performed in IEEE 14-bus test system show that the LS-PVPPs effectively decay the deteriorating impacts of disturbances and improve the stability status by performing timely remedial actions.

The inclusion of electric transportation systems generates more complex interactions among multiple grid components. The action of these elements actively affects the state of power distribution grids and their complexity for operation analyses, which requires proper studies in order to avoid potentially bad situations. A feasible answer to this constraint can be the usage of digital co-simulation that is a well-developed technique for the performance assessment of power systems. Therefore, this chapter presents a co-simulation tool for assessing the impact of electric railway traction systems into the grid. The co-simulation tool is applied to mass electric mobility interacting with an electric power system by means of OLE for process control (OPC), which allows controlling and supervising the communication between DIgSILENT PowerFactory and MATLAB–Simulink. DIgSILENT PowerFactory is used for railway and utility power systems simulation; meanwhile, MATLAB–Simulink simulates electrical drives as well as control and operation of asynchronous machines (i.e. the power electronic converters). The combination of both computer programs through OPC Simulation Server sets a powerful platform up to test complex control systems applied in traction systems of electric trains.

Variable-speed (VS) pumped storage technology has become a new trend for providing better support power system incorporating renewable energies. On the other hand, the transient stability of the power system can be affected by the application of such kind of storage unit. State-of-the-art pumped storage hydropower plants (PSHP) based on doubly fed induction machine (DFIM) known as variable-speed and conventional PSHP-based on synchronous machine (SM) known as fixed speed (FS) have a different effect on transient stability of a large-scale power system. This chapter intends to present the modelling and controller of DFIM-based PSHP of two types of PSHPs, i.e., VS and FS under generating operation mode in DIgSILENT software. Also, the IEEE 10-machine 39-bus system namely New England test system is adopted as a large power network. The results show that using DFIM-based VS-PSHP in the interconnected power grids, not only the oscillation modes of PSHP is eliminated, but also it can strongly improve rotor angle and voltage transient stability of the power system.

In order to ensure grid stability and due to the growth of newly installed wind power capacity worldwide, conduction of transient stability analyses is one of the current challenges for Transmission System Operators (TSOs) and Distribution System Operators (DSOs). TSOs and DSOs need to provide a safe, reliable and sustainable service to consumers, safeguarding the security of electricity supply. Due to the variable nature of wind, the integration of wind power into power systems has an impact on power grid planning and operation that needs assessment. The implementation and subsequent dynamic simulation of wind turbines connected to the grid are, therefore, necessary to achieve all the above requirements. This is where the International Electrotechnical Commission (IEC) comes in. The IEC 61400-27-1 defined four generic simulation models of wind turbines—Types 1, 2, 3 and 4—for transient stability analysis, covering the four main topologies of real wind turbines available in the market. Given that the Type 3 wind turbine, which represents a doubly-fed induction generator, is the most common topology installed and the most technologically advanced wind turbine model, it is implemented in this chapter. Using the DIgSILENT Simulation Language (DSL) functionality available in DIgSILENT PowerFactory, this chapter presents an extensive description of the generic Type 3 wind turbine model, and its implementation and simulation, following the IEC 61400-27-1 guidelines. In so doing, it details the step-by-step process followed to build the model and the adaptations required to simulate it in this powerful software tool.

The current trend of increased penetration of renewable energy and reduction in the number of large synchronous generators in existing power systems will inevitably lead to general system weakening. The inherent characteristics of traditional synchronous machines will have to be replaced by converter-interfaced sources. The intermittent nature of renewable sources points to a need for high capacity energy storage. Battery energy storage systems (BESS) are of a primary interest in terms of energy storage capabilities, but the potential of such systems can be expanded on the provision of ancillary services. In this chapter, we focus on developing a battery pack model in DIgSILENT PowerFactory simulation software and implementing several control strategies that can address some of the issues mentioned previously. The last section of the paper contains a demonstration of the capabilities of the battery system and evaluation of the implemented functions in various operating scenarios.

In this book chapter, a benchmark test system has been studied for power system stability considering the high share of power electronic converter-based generation. Furthermore, both conventional PI controllers and grid forming control have been taken in to account in order to study the impact of the high penetration of power electronic converter on the dynamic response of the power system.

In this book chapter, innovative protection schemes have been suggested to prevent bottlenecks of the power system considering the integration of offshore and onshore wind turbines and HVDC link. Four different countermeasures are proposed and investigated. Their effect on the system overloading and stability is also taken into account. The models for the simulation have been implemented in PowerFactory.

This chapter is dedicated to present some control mechanism to cope with the challenges due to the growth of the penetration level of the power electronic interfaced generation (PEIG) in sustainable interconnected energy systems. Specifically, this chapter presents different forms of fast active power injection (FAPI) control schemes for the analysis and development of different mitigation measures to address the frequency stability problem. Among the considered FAPI control schemes are the traditional droop-based scheme, and two propositions implemented in the form of a derivative-based control and a second-order virtual synchronous power (VSP)-based control. All the detailed explanation, DSL-based control is presented for the simulations in DIgSILENT software. Simulation results show that thanks to proposed FAPI controllers, it is possible to increase the maximum share of wind power generation without violating the threshold limits for frequency stability problem in low-inertia systems.

In this chapter, a grid forming control approach called direct voltage control (DVC) for wind turbine control with restoration capability of power system with a high share of power electronic-based generation units is presented and discussed. All the detailed explanation, DSL-based control is presented for dynamic simulations in DIgSILENT software.

In this chapter, a generic model of fuel cells and electrolysers suitable for power system stability studies has been developed in PowerFactory. Both theoretical modelling background and software implementation of fuel cells and electrolysers are detailed. Furthermore, a case study based on a three area test system has been performed, which provides valuable insight into the benefits that the synergy between the electricity and hydrogen sectors can bring to power system stability.

In this chapter, an integral approach for Grid-Forming and Black-Start capability of a large-scale interconnected Power System model is developed. This chapter introduces a model for Electro-Magnetic Transients (EMT) simulations, where a three-area power system is presented, containing different devices interfaced to the transmission network via voltage-source converters (VSC); seventeen wind power plants (WPP), seven battery-energy storage systems (BESS), and two HVDC transmission links. Of the total energy produced in this model, 90% is generated by the WPP and the other 10% by conventional generation units (CGU). The control systems that regulate the WPP and the HVDC stations were upgraded with Grid-Forming capability. Therefore, the power system model is suitable for simulations during both steady-state and transient operational scenarios. If the latter case may derive in a Blackout, it allows simulating Black-Start and Restoration strategies. The proposed grid-forming and black-start capabilities were tested with various EMT simulations reproducing severe short-circuit faults, deriving in a full blackout in one of the areas of the power system. The model also was upgraded with five protection relays with a restoration algorithm that determines the best re-energisation path for the fastest possible restoration strategy. The simulation results demonstrate that a power system with high penetration of converter-based generation and transmission is completely capable of managing a grid during all circumstances if its control systems are designed to do so, without encountering the problems arising from current injection control.

The main objective in this chapter is to develop and present a generic model for wind turbine (WT) which can be used for both DFIG- and FSCG-based WT for large-scale multi-machine power system dynamic studies. The presented model is developed for RMS simulation on PowerFactory, and it can be used as a replacement for both DFIG- and FSCG-based WTs without making any changes in the generic model itself. The generic RMS model is appropriate for the stability studies of large grids where the detailed dynamics, i.e., control action in the range of milliseconds, of the power electronic converter-based controllers do not play an important role.

This chapter presents a general overview of the experience learned with the use of DIgSILENT PowerFactory in the design of theoretical lectures and practical sessions of a power system dynamics course at postgraduate level. This chapter focuses on the experiences acquired in the course that is part of the MSc program in Electrical Engineering of TU Delft, Department of Electrical Sustainable Energy. The discussion provided in this chapter focuses on power systems application with special focus on (i) Steady-state, Dynamic, (ii) Voltage Stability and (iii) rotor angle stability. The main objective of using PowerFactory at MSc level is to expose the postgraduate students to real-life application, however, without lack of generalisation this chapter is dedicated to the is to expose to the application above by using a very well-known two area-four machine test power system (2A4G), it gives students insights and experience with cases closer to actual power systems. Results of this pedagogical experience demonstrate the importance of incorporating appropriate power system simulations tools in the postgraduate level.