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2012 | Book

FACTS-Devices and Applications Read chapter Read first chapter

Flexible AC Transmission Systems: Modelling and Control

Authors: Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal

Publisher: Springer Berlin Heidelberg

Book Series : Power Systems

Part of: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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About this book

The extended and revised second edition of this successful monograph presents advanced modeling, analysis and control techniques of Flexible AC Transmission Systems (FACTS). The book covers comprehensively a range of power-system control problems: from steady-state voltage and power flow control, to voltage and reactive power control, to voltage stability control, to small signal stability control using FACTS controllers.

In the six years since the first edition of the book has been published research on the FACTS has continued to flourish while renewable energy has developed into a mature and booming global green business. The second edition reflects the new developments in converter configuration, smart grid technologies, super power grid developments worldwide, new approaches for FACTS control design, new controllers for distribution system control, and power electronic controllers in wind generation operation and control. The latest trends of VSC-HVDC with multilevel architecture have been included and four completely new chapters have been added devoted to Multi-Agent Systems for Coordinated Control of FACTS-devices, Power System Stability Control using FACTS with Multiple Operating Points, Control of a Looping Device in a Distribution System, and Power Electronic Control for Wind Generation.

Table of Contents

Frontmatter
FACTS-Devices and Applications
Abstract
Flexible AC Transmission Systems, called FACTS, got in the recent years a well-known term for higher controllability in power systems by means of power electronic devices. Several FACTS-devices have been introduced for various applications worldwide. A number of new types of devices are in the stage of being introduced in practice. Even more concepts of configurations of FACTS-devices are discussed in research and literature.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Modeling of Multi-Functional Single Converter FACTS in Power Flow Analysis
Abstract
This chapter discusses the recent developments in modeling of multi-functional single converter FACTS-devices in power flow analysis. The objectives of this chapter are:
1. to model the well-recognized FACTS devices such as STATOM, SVC, SSSC and TCSC in power flow analysis,
2. to establish multi-control functional models of these FACTS-devices,
3. to handle various internal and external operating constraints of FACTS-devices.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Modeling of Multi-Converter FACTS in Power Flow Analysis
Abstract
This chapter discusses the recent developments in modeling of multi-functional multi-converter FACTS-devices in power flow analysis. The objectives of this chapter are:
1. to model not only the well-recognized two-converter shunt-series FACTS-device - UPFC, but also the latest multi-line FACTS-devices such as IPFC, GUPFC, VSC-HVDC and M-VSC-HVDC in power flow analysis,
2. to establish multi-control functional models of these multi-converter FACTS-devices to compare the control performance of these FACTS-devices.
3. to handle the small impedances of coupling transformers of FACTS-devices in power flow analysis.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Modeling of FACTS-Devices in Optimal Power Flow Analysis
Abstract
In recent years, energy, environment, deregulation of power utilities have delayed the construction of both generation facilities and new transmission lines. Better utilisation of existing power system capacities by installing new FACTS-devices has become imperative. FACTS-devices are able to change, in a fast and effective way, the network parameters in order to achieve a better system performance. FACTS-devices, such as phase shifter, shunt or series compensation and the most recent developed converter-based power electronic devices, make it possible to control circuit impedance, voltage angle and power flow for optimal operation of power systems, facilitate the development of competitive electric energy markets, and stipulate the unbundling the power generation from transmission and mandate open access to transmission services, etc.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Modeling of FACTS in Three-Phase Power Flow and Three-Phase OPF Analysis
Abstract
Three-phase power flow calculations are important tools to compute the realistic system operation states and evaluate the control performance of various control devices such as transformer, synchronous machines and FACTS-devices, particularly because (a) there are unbalances of three-phase transmission lines in high voltage transmission networks; (b) there are unbalanced three-phase loads; (c) in addition, there are one-phase or two-phase lines in some distribution networks, etc. Under these unbalanced operating conditions, three-phase power flow studies are needed to assess the realistic operating conditions of the systems and analyze the behavior and control performance of power system components including FACTS-devices.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Steady State Power System Voltage Stability Analysis and Control with FACTS
Abstract
Voltage stability analysis and control become increasingly important as the systems are being operated closer to their stability limits including voltage stability limits. This is due to the fact that there is lack of network investments and there are large amounts of power transactions across regions for economical reasons in electricity market environments. It has been recognized that a number of the system blackouts including the recent blackouts that happened in North America and Europe are related to voltage instabilities of the systems.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Steady State Voltage Stability of Unbalanced Three-Phase Power Systems
Abstract
This chapter discusses the recent developments in steady state unbalanced three phase voltage stability analysis and control with FACTS. The objectives of this chapter are:
1. to review steady state voltage stability analysis methods in unbalanced three-phase power systems;
2. to introduce the continuation three-phase power flow technique that can be used for steady state unbalanced three-phase voltage stability analysis;
3. to examine the PV curves of unbalanced three-phase power systems;
4. to reveal the interesting phenomena of voltage stability of unbalanced three-phase power systems;
5. to investigate the impact of FACTS controls on voltage stability limit of unbalanced three-phase power systems.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Congestion Management and Loss Optimization with FACTS
Abstract
This chapter focuses on power flow controlling FACTS-devices and their benefits in market environments. These devices have a significant influence on congestion management and loss reduction. Especially the speed of FACTS-devices provides an additional benefit in comparison to conventional power flow control methods. However, to earn these benefits a special post-contingency operation strategy has to be applied which will be explained in this chapter.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Non-intrusive System Control of FACTS
Abstract
For the implementation of FACTS-Devices, especially for controllable transmission paths in an AC-system, intensive planning studies and redesign of control and protection systems have to be executed. Adverse control interactions with other controllers and a lack of optimization potential due to predefined devices have to be considered. Applying a control architecture, which enables the operation of a new FACTS-device and especially a controlled transmission path without affecting the rest of the system, can eliminate these problems. This non-intrusiveness is the key issue of the so-called Non-Intrusive System Control (NISC) architecture. In this chapter the basic requirements and structure of this new control architecture are described first. A second focus is given to the problem of controller interactions in abnormal operation situations where the NISC architecture helps to avoid malfunctioning or adverse reactions.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Autonomous Systems for Emergency and Stability Control of FACTS
Abstract
The requirement specification in chapter 9 has clearly shown, that the uncoordinated use of FACTS-devices involves some negative effects and interactions with other devices, which leads to an endangerment of the steady-state and dynamical system security. This chapter shows one approach to overcome these difficulties and provides a solution for a coordinated control system fulfilling the specified requirements.
An autonomous control system for electrical power systems with embedded FACTS-devices is developed that provides the necessary preventive coordination. With methods of computational intelligence the system automatically generates specific coordinating measures from specified abstract coordinating rules for every operating condition of the power system without human intervention or control. This guarantees an optimal utilization of the technical advantages of FACTS-devices as well as the steady-state and dynamical system security. Interactions between the autonomous system and other existing controllers in electrical power systems are taken into consideration so that the autonomous system can completely be integrated into an existing conventional network control system.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Multi-agent Systems for Coordinated Control of FACTS-Devices
Abstract
This chapter targets on a multi-agent approach for an automated coordination and control of power flow controllers (PFC). In comparison to chapter 10 no central instance is required for the topology analysis. The agents derive the relevant actual topology through local communication and perform coordinated control actions according to the present situation. Therefore the approach can be implemented easily under the condition that a fast communication network between all network elements is available.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Wide Area Control of FACTS
Abstract
FACTS-control has always to cope with speed and in the case of power flow control with exchange of system wide information. The high speed exchange of data to react on contingencies needs to be ensured to fulfill the requirements of the NISC-architecture according to the specifications in chapter 9. Online monitoring of the system status is needed for the optimization of the FACTS-device applications. Especially for power flow control and power system oscillations a dynamic performance evaluation supports an optimized transmission capability and an adaptive damping control.
Although pioneered already in the 80s, it is not until now phasor measurement units (PMU) have become widely available in power systems [1]. However, since recently wide-area measurement systems based on PMUs are becoming proven technology and are seen by many utilities as one of the most promising ways to gain more detailed information to operate the networks closer to the limits. Typically a wide-area measurement system based on phasor measurements provides access to system-wide data with a time resolution of tens of Hertz. The amount of gathered data becomes large, and the data need proper processing to be used either for the operator support or as part of the control system especially for FACTS. This chapter discusses wide area measurement and control systems as part of the coordinating FACTS-control.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Modeling of Power Systems for Small Signal Stability Analysis with FACTS
Abstract
Small signal stability in a power system is the ability of the system to ascertain a stable operating condition following a small perturbation around its operating equilibrium. Power system disturbances can be broadly classified into two categories; large and small. Disturbances such as generation tripping, load outage, faults etc have severe influences on the system operation. These are large disturbances and the dynamic response and the stability conditions of the system are assessed within the standard framework of transient stability analysis and control. The system is modeled as a non-linear dynamic process. A large number of references dealing with this problem exist in power engineering literature [1]-[3]. Essentially the researchers have applied non-linear system theories and simulations to establish a clear understanding of the dynamic behavior of power system under such conditions. Effective tools to analyze and devise various non-linear control strategies are now in place.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Linear Control Design and Simulation of Power System Stability with FACTS
Abstract
Inter-area oscillations in power systems are triggered by, for example, disturbances such as variation in load demand or the action of voltage regulators due to a short circuit. The primary function of the damping controllers is to minimize the impact of these disturbances on the system within the limited dynamic rating of the actuator devices (excitation systems, FACTS-devices). In H  ∞  control term, this is equivalent to designing a controller that minimizes the infinity norm of a chosen mix of closed-loop quantities.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Power System Stability Control Using FACTS with Multiple Operating Points
Abstract
Power systems may operate on several operating conditions including post-fault operating conditions where it is challenging to design a FACTS damping controller that can achieve satisfactory performance over several operating conditions. When the nonlinear power system model is linearized around these operating conditions, a set of linearized state equations can formulate the multi-model system. So in principle the control design for the system with several operating points is to design a common controller for the multi-model system. Basically the output feedback problem of a multi-model system can be described by the nonlinear matrix inequalities (NMI). In the previous chapter, LMI approaches have been proposed to solve the damping control design on the nominal model (or single model) through suitable parameterization and transformation of the original NMI into the LMI problems. However, the LMI approaches and associated parameterization and transformation techniques are not applicable to the NMI for the multi-model system: In this Chapter, a two-step LMI based approach is proposed to design an output feedback controller for a multi-model system where the pole placement of the closed-loop system is considered. Then the proposed design approach is extended to H 2 and H  ∞  performances.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Control of a Looping Device in a Distribution System
Abstract
The Loop Power Controller (LPC) is a looping device for distribution systems which are usually operated with a radial configuration. This device can achieve various power quality improvements such as system voltage control when incorporating distributed generation (DG), balancing control of distribution feeder loadings and high speed compensation of voltage sags. The LPC is a promising device to form loop distribution systems without any increase in short-circuit current. In this chapter, a control method for the LPC is presented together with an approximate method for control and simulation and demonstration results of the approximate control. A 6.6 kV overhead distribution system in Japan is used as example for the simulation and demonstration.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Power Electronic Control for Wind Generation Systems
Abstract
Wind energy has mushroomed into a mature and booming global green business while generation costs have fallen dramatically. Modern wind turbine technologies have been improved significantly in their power rating, efficiency and reliability. Global wind energy capacity is up to 196.6 GW at the end of 2010. This Chapter covers
∙ mathematical models for wind turbines such as wind turbine (WT) with doubly fed induction generator (DFIG) and WT with direct-drive permanent magnet generator (DDPMG);
∙ small signal stability analysis and nonlinear control using power electronic back-to-back converters, which are very similar to those of UPFC and VSC HVDC;
∙ dynamic equivalent modeling of wind farms;
∙ and wind farm interconnection with power grid via VSC HVDC link.
Xiao-Ping Zhang, Christian Rehtanz, Bikash Pal
Backmatter
Metadata
Title
Flexible AC Transmission Systems: Modelling and Control
Authors
Xiao-Ping Zhang
Christian Rehtanz
Bikash Pal
Copyright Year
2012
Publisher
Springer Berlin Heidelberg
Electronic ISBN
978-3-642-28241-6
Print ISBN
978-3-642-28240-9
DOI
https://doi.org/10.1007/978-3-642-28241-6