Static Var Compensator Controller Research Articles

Development of a Control Algorithm for a Static VAR Compensator Used in Industrial Networks

In this paper a method for the development of a static VAR compensator (SVC) control algorithm is presented. The proposed algorithm has been designed with the objective of eliminating the negative impact of electric arc furnaces on the power system. First, a mathematical model of the proposed SVC controller in the d-q synchronous rotating coordinate system is developed. An analysis under dynamic and steady state conditions is also carried out. The efficiency of the presented controller is demonstrated by means of computer simulations of an actual steel-factory network model. The major advantages of the proposed controller are better flicker compensation, increased ability to regulate voltage and the need for only one-point network measurements.

UPFC with series and shunt FACTS controllers for the economic operation of a power system

This paper presents the application of Genetic Algorithm (GA) and Differential Evolution (DE) technique for the minimization of transmission loss and simultaneous reduction in the operating cost of the system using Flexible AC Transmission System (FACTS) devices. Three types of FACTS devices, Thyristor Controlled Series Compensator (TCSC), Static VAR Compensator (SVC) and Unified Power Flow Controller (UPFC) are considered for this purpose. Optimal placement of FACTS devices in the heavily loaded power system reduces transmission loss, control reactive power flow, improves voltage profile of all nodes and also reduces operating cost. The system is reactively loaded starting from base to 200% of base reactive load and the system performance is observed without and with FACTS devices. The proposed technique is applied on IEEE 30-bus system for the optimal setting of FACTS devices. Finally, how system performance is improved with the use of UPFC along with other series and shunt FACTS controller is illustrated.

Normal Form Analysis of the Subsynchronous Torsional Interaction with SVC in the Complex Power Systems

Due to the importance of nonlinear interactions in the complex power systems, in this paper the subsynchronous torsional interactions (SSTI) between turbine-generator shafts and flexible AC transmission system (FACTS) are studied using the nonlinear modal analysis method. Normal Form method is applied to study the nonlinear effects on the SSTI phenomenon in the presence of Static VAr Compensator (SVC) as a commonly used FACTS device. The results show that under stressed conditions the SVC voltage controller gains have an adverse effect on the nonlinear interactions of torsional modes. These effects can lead to severe excitation of torsional oscillations. The study also illustrates that the type of SVC control system model will play an important role in the nonlinear analysis of SSTI, and using a simple PI model is not suitable for nonlinear analysis of SSTI phenomenon. Moreover, in a multi-area power system, the location of SVC and its capacity have significant effects on the severity of nonlinear interactions of torsional modes.

Improvement of power system stability using genetically optimized SVC controller

Single machine infinite bus (SMIB) power system and multi-machine power system (MMPS) stability improvement by tuning of static var compensator (SVC) based controller parameters are investigated in the proposed method. The design problem is formulated as an optimization problem with a time-domain simulation-based objective function and real-coded genetic algorithm is used for searching optimal controller parameters. SMIB power system and MMPS models are developed using MATLAB’s SIMULINK which incorporates SVC controller. A fault is created on the transmission line. The simulation results of SMIB power system and MMPS without SVC controller and with SVC controller are presented. The simulation results are analyzed which show that the power system becomes unstable on the occurrence of the fault if SVC controller is not used. This paper proves the effectiveness of the proposed design. Thus the proposed method enhances the power system stability.

Improving Transient Stability with Multi-objective Allocation and Parameter Setting of SVC in a Multi-machine Power System

ABSTRACTThis paper aims to select the optimal location, size, and setting parameters of SVC (Static Var Compensator) controller using MOPSO (multi-objective particle swarm optimization) to improve the power system stability in a multi-machine power system. Though power system stabilizers are mandatory requirements for damping of oscillations, its performance still gets affected by changes in network configurations, load variations, etc. Hence, installations of SVC have been suggested in this paper to achieve appreciable damping of system oscillations. However, the performance of SVC highly depends upon its parameters, suitable location, and sizes in the power network. In order to find the solution, this problem is formulated as a multi-objective function. Then, MOPSO is used to find the best answers. In this paper, two objectives are considered to improve both the transient stability of the system and the SVC investment cost. The proposed method was tested on the 10-machine 39-busbar New England test system. The results of the nonlinear simulation show that the optimum sizing, siting, and parameter setting of SVC can improve greatly the transient stability of the multi-machine power system.

Design of the static var compensator adaptive sliding mode controller considering model uncertainty and time-delay

Using supplementary controller of static var compensator (SVC) is an effective way for enhancing the transient stability of an interconnected power system. In conventional controller design, SVC is usually considered as a first-order inertial model with known parameters. In this paper, a nonlinear controller design method based on adaptive sliding mode control is proposed to design a SVC supplementary controller. The imprecise of the model and the external disturbances such as time-delay are taking into consideration in the SVC model, and the interconnected system with SVC is considered by the center of inertia model. Then the SVC supplementary controller is designed based on the adaptive sliding control theory to improve the transient stability of the power system. Finally, the effectiveness of the proposed controller is verified using two simple systems. Simulation results show that the designed SVC sliding mode controller is robust to the variation of operation conditions and time-delays, and it has a better performance in enhancing the system stability as compared with the conventional SVC controller.

The Opportunity of Power Electronics on Improving the Quality of Voltage and Power Flow in the West Algeria Network

The Flexible Alternate Current Transmission Systems (FACTS) controllers improve quality of the supply power, enhance power system performance and also provide an optimal utilization of the existing resources. Especially the Thyristor Controlled Series Compensator (TCSC) and the Static Var Compensator (SVC) has been proposed to enhance the power transfer capability and improve the quality of the voltage by adjusting the line reactance. This paper, present a study of the west Algerian 2012 network. Furthermore, we will try to ask some problems encountered in practice, to find solutions and moving towards the FACTS devices in particular the TCSC and SVC controller, its application and technical advantage. The software NEPLAN is used to analyse the behaviour of the West Algerian electrical network without and with FACTS devices.

Design of SVC Controller Based on Improved Biogeography-Based Optimization Algorithm

Considering that common subsynchronous resonance controllers cannot adapt to the characteristics of the time-varying and nonlinear behavior of a power system, the cosine migration model, the improved migration operator, and the mutative scale of chaos and Cauchy mutation strategy are introduced into an improved biogeography-based optimization (IBBO) algorithm in order to design an optimal subsynchronous damping controller based on the mechanism of suppressing SSR by static var compensator (SVC). The effectiveness of the improved controller is verified by eigenvalue analysis and electromagnetic simulations. The simulation results of Jinjie plant indicate that the subsynchronous damping controller optimized by the IBBO algorithm can remarkably improve the damping of torsional modes and thus effectively depress SSR, and ensure the safety and stability of units and power grid operation. Moreover, the IBBO algorithm has the merits of a faster searching speed and higher searching accuracy in seeking the optimal control parameters over traditional algorithms, such as BBO algorithm, PSO algorithm, and GA algorithm.

Voltage Control of Static Var Compensator for a Remote System Interconnected by Long‐Distance AC Cables

SUMMARYThe voltage variation in a remote system is large when the system is connected by long‐distance AC cables due to the cable capacitance. In Japan, the longest 54‐km 66‐kV AC submarine cable interconnection between the Kyushu mainland and Goto Islands was commissioned in 2005. It was requested to mitigate the voltage variation caused by switching off and on one circuit of the two circuits in the AC cables when a fault occurs. Since the conventional voltage control methods such as transformer tap changer or shunt capacitor and reactor banks are not sufficient because of their slow response time, a static var compensator (SVC) was installed on the Goto Islands. In such an application, an SVC control method should be developed so as not to override the existing voltage control systems. This paper describes the SVC control method developed for the Goto Islands AC interconnection project, which can be applied to similar situations. The effectiveness of the control method was verified by the results of effective value simulation and of field testing, which was implemented before the SVC was commissioned in 2007. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 19–30, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22337

Optimal location and control of combined SVC–TCSC controller to enhance power system loadability

This paper presents a flexible strategy using combined differential evolution (DE) and adaptive particle swarm optimization to enhance the system loadability considering all power system security. The proposed strategy has been successfully adapted and applied for solving the multi objective system loadability in coordination with total power loss and total voltage deviation. Two well known FACTS devices, static VAR compensator (SVC) and thyristor controlled compensator (TCSC) are coordinated and installed at optimized location. The proposed algorithm optimizes simultaneously a combined control variables, active power generations, voltage generators, tap transformer, the reactive power controlled by the shunt SVC compensator in coordination with the active power controlled by the series TCSC controller to maximize the system loadability. The proposed approach has been examined and applied to the IEEE 30-Bus. Simulation results compared to the standard PSO and other recent methods confirm the effectiveness of this hybrid variant.

Decentralized robust control of multiple static var compensators via Hamiltonian function method

Using the energy-based Hamiltonian function method, this paper investigates the decentralized robust nonlinear control of multiple static var compensators (SVCs) in multimachine multiload power systems. First, the uncertain nonlinear differential algebraic equation model is constructed for the power system. Then, the dissipative Hamiltonian realization of the system is completed by means of variable transformation and prefeedback control. Finally, based on the obtained dissipative Hamiltonian realization, a decentralized robust nonlinear controller is put forward. The proposed controller can effectively utilize the internal structure and the energy balance property of the power system. Simulation results verify the effectiveness of the control scheme.

Adaptive fuzzy fault-tolerant control of static var compensator based on dynamic surface control technique

The adaptive fuzzy faults tolerant control problem is investigated for a single machine bus system with static var compensator (SVC). This design does not require that speed of the generator rotor and susceptance of the overall system are measured, and also does not require that the parameters of the controlled system are known accurately. The considered faults are modeled as both loss of effectiveness and lock-in-place. A fuzzy state observer is designed to estimate the speed of the generator rotor and susceptance, by combining the adaptive backstepping technique with a dynamic surface control (DSC) approach, a novel adaptive fuzzy output-feedback faults tolerant control approach is developed. It is proved that the proposed control approach can guarantee that all the signals in the closed-loop system are semiglobally uniformly ultimately bounded (SGUUB), and the angle of the generator rotor follows a desired value. Simulation results are presented to show the effectiveness of the approach.

스위칭 속도 및 온도 제어를 사용한 고압용 정지형 무효전력 보상장치의 안정화

본 논문에서는 고압용 정지형 무효전력 보상장치의 스위칭 모듈의 속도 제어 및 온도 제어 기법을 제안한다. 지속적인 전력 수요의 증가에 따른 발전 설비 및 송 배전설비의 신규 건설이 요구되고 있으며, 전력수송설비의 신 증설로 전력수송로의 병목현상에 따른 문제점이 나타나고 있다. 따라서 기존설비의 이용률을 극대화하고, 신규건설 없이 송전용량을 증대시키는 방안이 연구 되고 있다. 기존의 정지형 무효전력 보상장치 제어 방식에서는 전원입력회로에서 전위 검출하여 SCR를 직접 스위칭 동작하게 되어 있어서 노이즈가 발생하게 된다. 제안한 방법은 SCR 양단의 전위차를 바탕으로 스위칭 제어하여 스위칭 속도가 향상되고 노이즈가 감소하게 된다. 또한 스위칭 속도 증가로 발생하는 발열을 실시간 온도 제어함으로 안정성을 향상하였다. 실제 실험 환경을 구성하여 제안한 고압용 정지형 무효전력 보상장치의 속도 및 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다. 제안한 고압용 정지형 무효전력 보상장치의 스위칭 모듈을 통한 온도 제어를 실험하고, 실제 현장에서 성능을 검증하였다. In the paper, velocity controller of switching module and temperature controller for the high-voltage static var compensator are proposed. Because of the continuous increase in demand for electric power, transmission and distribution facilities of power plant are required. There is a bottleneck problem of transportation routes according to new construction and expansion of power transmission facilities. Therefore there are researches to maximize the utilization of existing facilities and to increase transmission capacity without new construction. The previous static var compensator detects voltage of input circuit of power, switches the SCR directly and generates switching noise. The proposed method increases switching velocity and decreases noise using switching control based on the voltage between both sides of SCR. Also the proposed method enhance the stability using realtime temperature control for heating of the system from increase of switching velocity. We experiment the velocity and temperature control of the proposed high-voltage static var compensator in the real environment and verify the performance of the proposed system by applying in the real field.

Optimal design of damping controllers using a new hybrid artificial bee colony algorithm

This paper integrates the artificial bee colony (ABC) algorithm with the sequential quadratic programming (SQP) to create the new hybrid optimization algorithm, ABC–SQP, for solving global optimization problems and damping of low frequency oscillations in power system stability analyses. The new algorithm combines the global exploration ability of ABC to converge rapidly to a near optimum solution and the accurate local exploitation ability of SQP to accelerate the search process and find an accurate solution. A set of well-known benchmark optimization problems is used to validate the performance of the ABC–SQP as a global optimization algorithm and to facilitate a comparison with the classical ABC. Numerical experiments demonstrate that the hybrid algorithm converges faster to a significantly more accurate final solution for a variety of benchmark test functions. Power system stabilizers and supplementary static VAR compensator controllers are designed for two-area–four-machine and five-area–sixteen-machine systems to illustrate the feasibility and effectiveness of the new method in power systems. The performance of the proposed ABC–SQP algorithm is compared with the classic ABC and the genetic algorithm (GA) through eigenvalue analysis and nonlinear time-domain simulation. The simulation results indicate that the controllers designed by the ABC–SQP perform better than those designed by ABC and GA.

Modeling and simulation of a wind farm in the presence of power electronic devices for the enhancement of transient stability

A comprehensive comparative study is made of a pitch control system and shunt flexible AC transmission system (FACTS) devices in order to improve large wind farm operation. Transient stability analysis of a large wind farm in the presence of superconducting magnetic energy storage (SMES), static synchronous compensator (STATCOM), static var compensator (SVC) and pitch controller is performed. The proposed control strategy of the STATCOM is based on PWM control; both the angle and the magnitude of the converter output voltage and the proposed SMES control system is based on a PWM voltage-source converter and a two-quadrant DC–DC chopper using an insulated-gate bipolar transistor (IGBT). Furthermore, robust control systems are designed for SVC and pitch controllers. To investigate the operation of the wind farm with contribution of these devices, two scenarios are considered and simulated. First, extensive analysis of a symmetrical three-phase fault and its effects on system operation is carried out. A permanent fault due to unsuccessful reclosing is analysed; this is one of the most noticeable features of this study. PSCAD/EMTDC software is used for modeling and simulation of the system components and proposed control strategies for power electronic interfaces. System performance analysis under different operating conditions and performance indices show the effectiveness of the proposed controllers even when a severe fault is applied.

Dynamic Modeling and Power Swing Damping Control (PSDC) of SVC Using ADPSS-Based Hardware-in-the-Loop (HID) Approach

This paper presents the dynamic modeling and power swing damping control (PSDC) of the static var compensator (SVC) using hardware-in-the-loop (HID) approach based on the advanced digital power system simulator (ADPSS) platform. A brief review of the SVC and the Phillips-Heffron model of the power system with the SVC controller are presented. The power swing damping control (PSDC) is devised to enhance power system damping and mitigate low frequency oscillation of the power system under grid disturbance conditions. The coordinated HID-based real-time digital simulation method using the electromagnetic and electromechanical transient programs is proposed. To analyze the dynamic and transient control behavior of the SVC, the closed-loop control strategy of the SVC controller on the ADPSS platform is designed. The validity and effectiveness of the modeling and control methods are confirmed by the experimental results

Adaptive neuro‐fuzzy controller for static VAR compensator to damp out wind energy conversion system oscillation

Wind shear and tower shadow produce a periodic pulse reduction in mechanical torque captured from wind energy resulting in wind energy conversion system (WECS) active power oscillations. In this study, an adaptive neuro-fuzzy controller for static VAR compensator, used in power networks integrated with WECS, is presented to address the torque oscillation problem. The proposed controller consists of a radial basis function neural network representing a third-order auto-regressive and moving average system model and performing the prediction, and a main controller with adaptive neuro-fuzzy inference system providing the damping signal. A modified two-area four-machine power network with WECS integration is applied to validate the proposed implementation, compared with conventional lead/lag compensation. Time-domain simulations prove that the proposed controller can provide a damping signal to improve the active power oscillation and system dynamic stability, influenced by torque oscillations under WECSs synchronised operating condition.

Sliding‐mode variable structure controller for cascade STATic var COMpensator

The authors propose a novel sliding-mode variable structure controller for cascade STATic var COMpensator (STATCOM), which integrates the direct feedback linearisation control for the balanced system and the individual phase instantaneous current tracking control for the unbalanced system, to achieve a versatile STATCOM controller. It can adapt automatically to various distribution system conditions. Based on the degree of system unbalance, the authors design a switching function to make the STATCOM work reliably with satisfactory performance, when the serious voltage sag occurs or the distribution system enters serious asymmetrical condition. The authors also propose a hierarchical DC-link voltages balance control strategy. The authors build a detailed ± 10 MVar STATCOM model with power system CAD and electro magnetic transient in DC system (PSCAD/EMTDC) and validate the effectiveness and advantage of the proposed control strategy with the simulation study.

Adaptive fuzzy backstepping control of static var compensator based on state observer

The robust adaptive fuzzy control problem is investigated for a single machine bus system with static var compensator (SVC). This design does not require that speed of the generator rotor and susceptance of the overall system are measured, and also does not require that the parameters of controlled system are known accurately. The fuzzy logic systems are used to approximate the nonlinear functions of the system, and a fuzzy state observer is designed to estimate the speed of the generator rotor and susceptance. By utilizing the fuzzy state observer, and combining the adaptive backstepping technique with adaptive fuzzy control design, an observer-based adaptive fuzzy output-feedback control approach is developed. It is proved that the proposed control approach can guarantee that all the signals in the closed-loop system are semiglobally uniformly ultimately bounded (SGUUB), and the angle of the generator rotor follows a desired value. Simulation results are presented to show the effectiveness of the approach.

Hybrid adaptive robust control of static var compensator in power systems

SUMMARY To improve the transient response of an electric power transmission system, a hybrid adaptive robust control method is proposed in this paper for the static var compensator by incorporating the immersion and invariance adaptive (I&I adaptive) and L2-gain control. In contrast to the standard I&I adaptive control algorithm, establishing a target system is not required in constructing the robust control law with the proposed method. Thus, the procedure of solving PDEs to satisfy the immersion condition can be avoided. In addition, both parametric and non-parametric uncertainties, which commonly exist in electric power transmission systems, are considered. The parametric uncertainty induced by the damping coefficient of the system is estimated by the designed adaptive law, which is constructed by ensuring the estimation error converges to zero. The non-parametric uncertainty is caused by external disturbances and approximation errors in modeling the uncertain structure. By assuming that the L2-gain of the system to the non-parametric uncertainties satisfies a dissipation inequality, we found that the robustness of the controller can be guaranteed. It is proved that all the system states are globally bounded and converge to a new stable equilibrium. Simulation results are also presented to show the effectiveness of the proposed control method in improving the transient response of the system and the convergence speed of the system states. Copyright © 2013 John Wiley & Sons, Ltd.