Use of UPFC for optimal power flow control
TL;DR: In this paper, the optimal power flow control in electric power systems by the use of a unified power flow controller (UPFC) has been investigated and models suitable for incorporation in power flow programs are developed and analyzed.
Abstract: This paper deals with optimal power flow control in electric power systems by the use of a unified power flow controller (UPFC). Models suitable for incorporation in power flow programs are developed and analysed. The application of UPFC for optimal power flow control is demonstrated through numerical examples. It is shown that a UPFC has the capability of regulating the power flow and minimising the power losses simultaneously. An algorithm is proposed for determining the optimum size of UPFC for power flow applications. The performance of UPFC is compared with that of a phase shifting transformer (PST).
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27 Feb 2002
TL;DR: In this paper, the authors present a comparison of different SVC controllers for power transmission networks with respect to their performance in terms of the number of SVC inputs and outputs, as well as the frequency of the SVC outputs.
Abstract: 1. Introduction. 1.1 Background. 1.2 Electrical Transmission Networks. 1.3 Conventional Control Mechanisms. 1.4 Flexible ac Transmission Systems (FACTS). 1.5 Emerging Transmission Networks. 2. Reactor--Power Control in Electrical Power Transmission Systems. 2.1 Reacrive Power. 2.2 Uncompensated Transmission Lines. 2.3 Passive Compensation. 2.4 Summary. 3. Principles of Conventional Reactive--Power Compensators. 3.1 Introduction. 3.2 Synchronous Condensers. 3.3 The Saturated Reactor (SR). 3.4 The Thyristor--Controlled Reactor (TCR). 3.5 The Thyristor--Controlled Transformer (TCT). 3.6 The Fixed Capacitor--Thyristor--Controlled Reactor (FC--TCR). 3.7 The Mechanically Switched Capacitor--Thristor--Controlled Reactor (MSC--TCR). 3.8 The Thyristor--Switched capacitor and Reactor. 3.9 The Thyristor--Switched capacitor--Thyristor--Controlled Reactor (TSC--TCR). 3.10 A Comparison of Different SVCs. 3.11 Summary. 4. SVC Control Components and Models. 4.1 Introduction 4.2 Measurement Systems. 4.3 The Voltage Regulator. 4.4 Gate--Pulse Generation. 4.5 The Synchronizing System. 4.6 Additional Control and Protection Functions. 4.7 Modeling of SVC for Power--System Studies. 4.8 Summary. 5. Conceepts of SVC Voltage Control. 5.1 Introduction 5.2 Voltage Control. 5.3 Effect of Network Resonances on the Controller Response. 5.4 The 2nd Harmonic Interaction Between the SVC and ac Network. 5.5 Application of the SVC to Series--Compensated ac Systems. 5.6 3rd Harmonic Distortion. 5.7 Voltage--Controlled Design Studies. 5.8 Summary. 6. Applications. 6.1 Introduction. 6.2 Increase in Steady--State Power--Transfer Capacity. 6.3 Enhancement of Transient Stability. 6.4 Augmentation of Power--System Damping. 6.5 SVC Mitigation of Subsychronous Resonance (SSR). 6.6 Prevention of Voltage Instability. 6.7 Improvement of HVDC Link Performance. 6.8 Summary. 7. The Thyristor--Controlled SeriesCapacitor (TCSC). 7.1 Series Compensation. 7.2 The TCSC Controller. 7.3 Operation of the TCSC. 7.4 The TSSC. 7.5 Analysis of the TCSC. 7.6 Capability Characteristics. 7.7 Harmonic Performance. 7.8 Losses. 7.9 Response of the TCSC. 7.10 Modeling of the TCSC. 7.11 Summary. 8. TCSC Applications. 8.1 Introduction. 8.2 Open--Loop Control. 8.3 Closed--Loop Control. 8.4 Improvement of the System--Stability Limit. 8.5 Enhancement of System Damping. 8.6 Subsynchronous Resonanace (SSR) Mitigation. 8.7 Voltage--Collapse Prevention. 8.8 TCSC Installations. 8.9 Summary. 9. Coordination of FACTS Controllers. 9.1 Introduction 9.2 Controller Interactions. 9.3 SVC--SVC Interaction. 9.4 SVC--HVDC Interaction. 9.5 SVC--TCSC Interaction. 9.6 TCSC--TCSC Interaction. 9.7 Performance Criteria for Damping--Controller Design. 9.8 Coordination of Multiple Controllers Using Linear--Control Techniques. 9.9 Coordination of Multiple Controllers using Nonlinear--Control Techniques. 9.10 Summary. 10. Emerging FACTS Controllers. 10.1 Introduction. 10.2 The STATCOM. 10.3 THE SSSC. 10.4 The UPFC. 10.5 Comparative Evaluation of Different FACTS Controllers. 10.6 Future Direction of FACTS Technology. 10.7 Summary. Appendix A. Design of an SVC Voltage Regulator. A.1 Study System. A.2 Method of System Gain. A.3 Elgen Value Analysis. A.4 Simulator Studies. A.5 A Comparison of Physical Simulator results With Analytical and Digital Simulator Results Using Linearized Models. Appendix B. Transient--Stability Enhancement in a Midpoint SVC--Compensated SMIB System. Appendix C. Approximate Multimodal decomposition Method for the Design of FACTS Controllers. C.1 Introduction. C.2 Modal Analysis of the ith Swing Mode, C.3 Implications of Different Transfer Functions. C.4 Design of the Damping Controller. Appendix D. FACTS Terms and Definitions. Index.
954 citations
Book•
21 Jun 2005
TL;DR: In this article, the authors proposed a mixed sensitivity approach using Linear Matrix Inequalities (LMIIN) for loop-shaping in power systems. And they also proposed a control for time-delayed systems.
Abstract: Power System Oscillations.- Linear Control in Power Systems.- Test System Model.- Power System Stabilizers.- Multiple-Model Adaptive Control Approach.- Simultaneous Stabilization.- Mixed-Sensitivity Approach Using Linear Matrix Inequalities.- Normalized ?? Loop-Shaping Using Linear Matrix Inequalities.- ?? Control For Time-Delayed Systems.
716 citations
07 Sep 2003
TL;DR: In this article, a combined natural gas and electric optimal power flow (GEOPF) problem is presented, where the authors show fundamental modeling of the natural gas network to be used for the GEOPF, and describes the equality constraints, which describe the energy transformation between gas and electricity networks at combined nodes (i.e., generators).
Abstract: In this paper, the combined natural gas and electric optimal power flow (GEOPF) problem is presented. It shows fundamental modeling of the natural gas network to be used for the GEOPF, and describes the equality constraints, which describe the energy transformation between gas and electric networks at combined nodes (i.e., generators). We also present the formulation of the natural gas load flow problem, which includes the amount of gas consumed in compressor stations. Case studies are presented to show the sensitivity of the real power generation to wellhead gas prices. Results from the simulation demonstrate that the GEOPF can provide social welfare maximizing solutions considering both gas and electric networks.
293 citations
TL;DR: In this paper, a control strategy for the damping of electromechanical power oscillations using an energy function method is derived, which is shown to be effective both for damping large signal and small signal disturbances and are robust with respect to loading condition, fault location and network structure.
Abstract: This paper examines improvement of power system dynamics by use of unified power flow controllers, thyristor controlled phase shifting transformers and thyristor controlled series capacitors. Models suitable for incorporation in dynamic simulation programs for studying angle stability are analysed. A control strategy for the damping of electromechanical power oscillations using an energy function method is derived. The achieved control laws are shown to be effective both for the damping of large signal and small signal disturbances and are robust with respect to loading condition, fault location and network structure. Furthermore, the control inputs are easily attainable from locally measurable variables. The effectiveness of the controls are demonstrated for model power systems.
279 citations
TL;DR: In this article, the authors deal with the simultaneous coordinated tuning of the flexible AC transmission systems (FACTS) power oscillation damping controller and the conventional power system stabilizer (PSS) controllers in multi-machine power systems.
Abstract: This work deals with the simultaneous coordinated tuning of the flexible AC transmission systems (FACTS) power oscillation damping controller and the conventional power system stabilizer (PSS) controllers in multi-machine power systems. Using the linearized system model and the parameter-constrained nonlinear optimization algorithm, interactions among FACTS controller and PSS controllers are considered. Furthermore, the parameters of the damping controllers are optimized simultaneously. Simulation results of multi-machine power system validate the efficiency of this approach. The proposed method is effective for the tuning of multi-controllers in large power systems.
265 citations
Cites methods from "Use of UPFC for optimal power flow ..."
...Each generator is described by a sixth-order model and the series FACTS device is simulated using a power-injection model [4], [10], [12]....
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References
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TL;DR: In this paper, the authors proposed a unified power flow controller (UPFC) that is able to control both the transmitted real power and, independently, the reactive power flows at the sending-and the receiving-end of the transmission line.
Abstract: This paper shows that the unified power flow controller (UPFC) is able to control both the transmitted real power and, independently, the reactive power flows at the sending- and the receiving-end of the transmission line. The unique capabilities of the UPFC in multiple line compensation are integrated into a generalized power flow controller that is able to maintain prescribed, and independently controllable, real power and reactive power flow in the line. The paper describes the basic concepts of the proposed generalized P and Q controller and compares it to the more conventional, but related power flow controllers, such as the thyristor-controlled series capacitor and thyristor-controlled phase angle regulator. The paper also presents results of computer simulations showing the performance of the UPFC under different system conditions. >
997 citations
TL;DR: In this article, a synchronous voltage source is implemented by a multi-pulse inverter using gate turn-off (GTO) thyristors for shunt compensation, series and phase angle control.
Abstract: This paper describes a novel approach in which solid-state synchronous voltage sources are employed for the dynamic compensation and real time control of power flow in transmission systems. The synchronous voltage source is implemented by a multi-pulse inverter using gate turn-off (GTO) thyristors. It is capable of generating internally the reactive power necessary for network compensation, and is also able to interface with an appropriate energy storage device to negotiate real power exchange with the AC system. The paper develops a comprehensive treatment of power flow control using solid-state synchronous voltage sources for shunt compensation, series and phase angle control. It also describes the unique unified power flow controller that is able to control concurrently or selectively all three network parameters (voltage, impedance, transmission angle) determining power transmission. Comparison of the synchronous voltage source approach with the more conventional compensation method of employing thyristor-switched capacitors and reactors shows its superior performance (including the unmatched capability of using both reactive and real power compensation to counteract dynamic disturbances), uniform applicability, smaller physical size, and potentially lower overall cost. >
553 citations
TL;DR: In this article, power flow control in electric power systems by use of controllable series power capacitors and phase shifters is discussed and models suitable for incorporation in power flow programs are developed and analyzed.
Abstract: Power flow control in electric power systems by use of controllable series power capacitors and phase shifters is discussed. Models suitable for incorporation in power flow programs are developed and analyzed. The power flow control problem is defined in a stringent way, and a method for solving the power flow control problem is proposed based on decomposition. This method is applied on test systems and the convergence rate of the algorithm is discussed. Simplified models of the components are also derived. These simplified models are shown to be quite accurate in most situations, and are used to construct regions of feasible power flows of the controlled lines. >
187 citations
TL;DR: In this paper, the effect of a unified power flow controller (UPFC) on transient stability margin enhancement of a longitudinal power system is analyzed, and three controllable UPFC parameters are determined during the digital simulation process performed by the NETOMAC simulation program.
Abstract: The aim of the paper is to analyze the effect of a unified power flow controller (UPFC) on transient stability margin enhancement of a longitudinal power system. To utilize the UPFC possibilities fully, the three controllable UPFC parameters were determined during the digital simulation process performed by the NETOMAC simulation program. The basis for determination of the suitable damping strategy and for determination of the optimal UPFC parameters is a mathematical model, which describes the interdependence between longitudinal transmission system parameters, operating conditions and UPFC parameters in the form of analytical equations. On the basis of the mathematical model, the theoretical UPFC limits were also detected, and their appearance explained.
183 citations