Static Var Compensator Controller Research Articles

THE IMPACT OF THE UNIFIED POWER FLOW CONTROLLER ON MAXIMIZATION OF LOADABILITY OF ELECTRIC POWER GRID

The building of additional transmission network to meet the demand of the ever-increasing load is expensive, and time consuming. An alternative to constructing new lines is the incorporation of the Flexible Alternating Current Transmission System (FACTS); in which a Unified Power Flow Controller (UPFC) is a member of the ménage, which can be modelled as a combination of Static Var Compensator and Thyristor Control Series Compensator. This study determines the optimal location of the UPFC by randomly adding loads to the existing transmission network until the Fast Voltage Stability Index of one of the lines is at a critical point. This is the vital line in which UPFC components are added. The sizing of the components of the UPFC is determined using Artificial Bee Colony algorithm. The IEEE 30-bus network is exploited as the test bed. The results obtained reveal that the optimal positioning and sizing of the UPFC for the purpose of maximizing loadability of the grid when load angles are assumed to be negligible are the same as when the load angles are considered. The loadability of the test bed when UPFC is not injected in the grid is 440.376 MW, whereas, it is 837.915 MW when the UPFC is optimally located and sized; and this represents 90.27 %. The sizes of the shunt and series components of the UPFC that assist in realizing this maximization are -0.2780 pu and 0.1000 pu respectively.

A Novel Modified Lightning Attachment Procedure Optimization Technique for Optimal Allocation of the FACTS Devices in Power Systems

The Flexible AC Transmission Systems (FACTS) are the static power electronic devices that are installed and used in AC transmission networks to enhance the capability of transferring the power for providing the controllability and stability. However, the optimization of site and size of these devices is a crucial task due to their high capital cost and practical capabilities. In this paper, the optimal reactive power dispatch (ORPD) embedded with two effective controllers including the Static VAR Compensator (SVC) and Thyristor Control Series Capacitor (TCSC) is solved using a Modified Lightning Attachment Procedure Optimizer (MLAPO). The searching capability of basic LAPO is enhanced and the stagnation of basic LAPO is avoided by application of levy flight distribution and spiral orientation motion. The optimization for these devices is for reducing the power losses, voltage deviations, and the operating cost. MLAPO is examined and tested on modified IEEE30 and IEEE57 bus-standards considering SVC and TCSC. The effectiveness of MLAPO is further analyzed and compared with the outcomes of the well-known optimization techniques namely LAPO, PSO, ALO, EO, MPA, WOA and SCA with and without FACTS devices.

WITHDRAWN: Wavelet based multiresolution analysis of a 5-Bus system in the presence SVC controller under fault and sudden load conditions

Abstract The changes in power quality are very quick and a difficult task to know under power networks. Most of the power quality issues are observed in interconnected networks due to different sources of power generation can be attributed to temporary faults and sudden loading conditions. The Flexible AC Transmission Systems (FACTS) provide one of the fastest controls of reactive and active power through a multi bus system. The Static Var Compensator (SVC) is one of the FACTS controllers with reasonably good features. Operating with multi terminal systems, when incorporating with FACTS devices are very complex in power systems which needs effective and detailed study, particularly for fault identification. The present research work explores the analysis of wavelet multiresolution with the usage of the mother wavelet Bior1.5 for different Power Quality problems are presented to evaluate the analysis of a 5-bus network. In this work different power quality issues are tested during different faulty conditions and when sudden load of 50 MW injecting in to the line conditions and the performance and effectiveness is analysed in the environment of SVC. The effectiveness of wavelets is useful to find out the fault in under different fault conditions as well as under sudden loading conditions.

FLC based on static var compensator for power system transient stability enhancement

Transient Stability is the capability of a system to be able to return to its normal state after experiencing large disturbances. The static var compensator (SVC) is a shunt device of the flexible AC transmission systems (FACTS) family using power electronics to improve transient stability in power system. For the SVC control, it is usually used a PI controller, although PI controller is simpler and cheaper but not suitable when power system is subjected to transient stability since power system become non-linear system. In order to overcome this problem, the PI controller combined with Fuzzy controller is designed. Two types of faults were considered for this study to examine the effect of the fuzzy-SVC controller on system transient stability, the proposed fault types are single line to ground fault and three lines to ground fault. The performance and behavior of the designed fuzzy controller compared with that of the conventional PI controller in term of terminal voltage, rotor angle, and transmission line active power.

Power flow simulation & voltage control in a SPV IEEE-5 bus system based on SVC

Static var Compensator (SVC) can be controlled in a coordinated manner for achieving the voltage regulation and transient stability for increasing the performance of power system. In this paper some linearization techniques like parameter uncertainties are considered for increasing the performance of the system. SVC can enhance the plant parameters for improved power flow, voltage stability and transient stability. In this paper a simulink model has been presented in MATLAB where main focus is to integrate the SVC controller with Solar photovoltaic (SPV) as Generator bus, so that voltage regulation, loss minimization & nodal voltage magnitude improvement can be done properly. Optimal location of these FACTS devices at various buses can be specified by means of minimum real & reactive Power flow, Power loss and enhancement of p.u. nodal voltage magnitude at each bus. At the end of the paper results were analysed.

Dynamic performance testing and implementation for static var compensator controller via hardware-in-the-loop simulation under large-scale power system with real-time simulators

Recently, the number of electric-power facilities, including high-voltage direct current (HVDC) and flexible AC current transmission system (FACTS), has rapidly increased, owing to restrictions regarding the expansion of existing AC networks. Traditionally, a final site acceptance test (SAT) is conducted following controller performance verification in a factory acceptance test (FAT), based on an equivalent small network or voltage sources. Furthermore, several standards and guidelines related to the FAT and SAT of HVDC and FACTS have been published. Meanwhile, as the number of power electronic devices and the complexity of power systems increase, controller performance tests reflecting the wide area dynamic characteristics and control operation of adjacent devices should be required. However, a wide-area dynamic performance test (DPT) requires a large-scale real-time simulator and high-level operational technology. Owing to these difficulties, the definition, standard, procedure, and test protocol of hardware-in-the-loop simulation (HILS)-DPT, based on a large-scale power system, have not yet been established systematically, and only a few applications have been reported. This study aims to establish and propose procedures, a test protocol, and a methodology of HILS-DPT and large-scale power system modeling for testing. To this end, a case study was conducted to demonstrate the necessity of the DPT procedures and methodologies for the static VAR compensator controller installed at the Shin-Jecheon substation, an ongoing project undertaken the by Korea Electric Power Corporation, as of 2019.

Improvement optimal power flow solution considering SVC and TCSC controllers using new partitioned ant lion algorithm

This paper introduces a new partitioned ant lion optimizer (PALO) strategy to improve the solution accuracy and quality of the optimal power flow (OPF) considering multi Static VAR Compensator (SVC) and Thyristor Controlled Series Controller (TCSC)-based FACTS devices. An interactive partitioning structure-based ALO is proposed to improve the solution of OPF by creating an interactive equilibrium between diversification and intensification during the search process. The decision variables such as active power, voltage magnitudes of generating units, tap transformers; reactive power of Static VAR Compensator (SVC), and the reactance of TCSC devices are optimized using a flexible partitioned process. Three objective functions, such as total fuel cost, total power loss, and total voltage deviation have been optimized considering load growth. The robustness of the proposed PALO has been validated on three test systems, the IEEE 30-bus, and two large test systems, the 300-bus and 2736 ps bus of the Polish power system. Results compared to many recent techniques prove the particularity and competitiveness of the proposed optimization strategy-based PALO.

RETRACTED ARTICLE: Estimation of loadability limit with N-1 and N-2 outages using evolutionary computation techniques

Voltage stability primarily depends on the voltage magnitude, phase angle, real and reactive power constraint of the electric power system. Even during emergencies like contingency (outages), the stability of the electric power structure will be enhanced by improving the Loadability Limit (LL) of the transmission sector. Flexibility in the real and reactive power flow in the transmission system is achieved by the Flexible AC Transmission System (FACTS) devices. These devices can be placed anywhere in the transmission sector. To get effective control over the power flow through the transmission lines and to achieve the maximum loadability with the minimal installation cost, optimal choice and placement of FACTS devices are essential. In this manuscript, efforts had been taken to analyze the LL with outages for hybrid electric power structures. The proposed method is simulated and tested with the hybrid version of standard IEEE 30 bus system. Three types of FACTS devices like Thyristor Controlled Series Capacitor (TCSC), Static VAr Compensator (SVC) and Unified Power Flow Controller (UPFC) are efficiently selected and placed in the transmission lines. For the optimal positioning and placement of these devices, the Contingency Severity Index (CSI) and Fast Voltage Stability Index (FVSI) have been used. Differential Evolution (DE) and Modified Differential Evolution (MDE) algorithms are applied to optimize the obtained results. DE is an evolutionary search based soft computing algorithm popularly handed to resolve multifarious problems. MDE is the enhanced version of DE that embraces a prior knowledge about the solution space at every stage of the search. The main focus of this work is (i) to identify the weak branches and buses in the system using CSI and FVSI. (ii) to optimize the number, location and settings of FACTS devices using various soft computing techniques like DE and MDE. (iii) to evaluate ML of a transmission system with FACTS devices under normal and contingency conditions using DE and MDE. (iv) to calculate the cost required for the installation of FACTS devices. (v) to enhance ML of pool and hybrid model of deregulated electric power market with contingency using the optimal number, rating and positioning of FACTS devices.

Coordinated Excitation and Static Var Compensator Control with Delayed Feedback Measurements in SGIB Power Systems

In this paper, we present a nonlinear coordinated excitation and static var compensator (SVC) control for regulating the output voltage and improving the transient stability of a synchronous generator infinite bus (SGIB) power system. In the first stage, advanced nonlinear methods are applied to regulate the SVC susceptance in a manner that can potentially improve the overall transient performance and stability. However, as distant from the generator measurements are needed, time delays are expected in the control loop. This fact substantially complicates the whole design. Therefore, a novel design is proposed that uses backstepping methodologies and feedback linearization techniques suitably modified to take into account the delayed measurement feedback laws in order to implement both the excitation voltage and the SVC compensator input. A detailed and rigorous Lyapunov stability analysis reveals that if the time delays do not exceed some specific limits, then all closed-loop signals remain bounded and the frequency deviations are effectively regulated to approach zero. Applying this control scheme, output voltage changes occur after the large power angle deviations have been eliminated. The scheme is thus completed, in a second stage, by a soft-switching mechanism employed on a classical proportional integral (PI) PI voltage controller acting on the excitation loop when the frequency deviations tend to zero in order to smoothly recover the output voltage level at its nominal value. Detailed simulation studies verify the effectiveness of the proposed design approach.

Voltage Stability Enhancement for Microgrid Using an SVC

This paper presents comparative simulation results of a Microgrid (MG) system using a Static Var Compensator (SVC) for improving the voltage stability of the studied system. An Adaptive Neural Fuzzy Inference System (ANFIS) controller is designed based on the feedback signals to control the proposed SVC. For simplicity, the studied MG system can be modeled as an equivalent small scale wind turbine generator (WTG) combine with a Solar Photovoltaic (PV) and a Battery that connected to the common AC bus. A time-domain approach based on nonlinear model simulations is systematically performed. By observing the simulation results it can be concluded that the designed ANFIS controller for SVC can offer better damping characteristics of the studied MG system under severe operating conditions

Optimization of controllers parameters for damping local area oscillation to enhance the stability of an interconnected system with wind farm

In a power system with renewable energy sources, the Low-Frequency Oscillatory (LFO) modes arise due to the intermittent nature of wind power, loading and generating conditions. This is undesirable and results in system instability. If these LFO modes are not controlled, it may lead to a power interruption and results in unstable. The LFO modes are damped by Power System Stabilizers (PSS). However, it causes variation in voltage profile resulting in reduction instability of the system during large disturbances. In such cases, the flexible ac transmission system controllers are required. This paper presents and compares the PSS, Static synchronous Compensator (STATCOM) and Static Var Compensator (SVC) controller by replacing Synchronous Generator (SG) with same rated wind farm and various wind power penetration levels by considering system uncertainties such as wind speed. In this paper, a robust coordinated method is proposed using Particle Swarm Optimization (PSO) for optimizing parameters of controllers of PSS, SVC, and STATCOM. The real part and damping ratio of eigenvalues is the objective function for PSO and is formulated based on the small-signal and transient analysis. Controller locations are determined by the deterministic method, probabilistic method and power flow sensitivity analysis. An eigenvalue analysis approach based on the linearization of a nonlinear system using a state-space model is conducted to analyse the Small Signal Stability performance. Time-domain simulation is carried out for transient stability under large disturbance. The robustness and effectiveness of the proposed approaches for transient and small-signal stability are evaluated on the IEEE-14-bus system. The results reveal that the proposed location and optimized gain parameters for controllers effectively damped the LFOs. It also intensifies the transient capability under extreme disturbances and shows enhancement in system stability.

Hardware-in-the-Loop Testing of Dynamic Grid Voltages for Static Var Compensator Controllers With Single-Phase Induction Motor Loads

This paper investigates the interaction between two Static var Compensators (SVCs) to verify dynamic grid voltage support is maintained and that the SVC controllers do not negatively interact with each other. For this purpose, the controls of the SVCs with all of the remotely controlled Mechanically-Switched Capacitors (MSCs) have been tested in a closed-loop real-time simulator environment using SVC replicas (physical controllers) of the actual field installations. To accurately capture the power system’s response to phenomenon such as potential Fault Induced Delayed Voltage Recovery (FIDVR), the dynamics of the generators and the motor loads are modeled in the simulations. A hybrid model consisting of real and reactive power (P-Q) loads and aggregated motor load of a single-phase induction motor suitable for three-phase time-domain simulation was developed and connected to the power system. The developed aggregate motor load model includes details such as the main winding, auxiliary winding, starting capacitor, motor inertia, and distribution transformers. It is observed that dynamic grid voltage support can be maintained and the SVC controllers do not negatively interact with each other if all the SVC control blocks are enabled and function normally.

Embedded Electrical Network Advance Controlling Based on SVC Device and Automatic Voltage Regulator

This paper studies the control of embedded electrical network (EEN), which can be described as multi-turbo-alternators connected in parallel with various linear or nonlinear loads, and poorly known characteristics. Moreover, the transfer function of global model will be obtained using the perturbation singular method, by linearization model and separation of fast and slow variables. Then, the control of small disturbances will be performed by an automatic voltage regulator using three-phase PWM rectifier. Moreover, the static VAR compensator (SVC) device is implemented in embedded network to control the voltage stability for a large disturbance when the network is affected by voltage dip or open circuit. The SVC will be controlled by adjusting exactly the firing angle of thyristors that will improve the voltage stability at the bus bar, by injecting or absorbing the reactive power. The SVC control algorithm is firstly simulated in real time using a microcontroller device, for a variable load, after will be implemented in MATLAB/Simulink S-Function, to verify its efficiency with the EEN.

Design of nonlinear coordinate damping controller for HVDC and SVC based on synergetic control

This article presents a novel nonlinear coordinate damping controller (NCDC) for high‐voltage direct current (HVDC) and static var compensator (SVC) based on synergetic control theory, which can improve the stability of interarea power system and multi‐infeed HVDC system by quickly changing the transmission power of HVDC and reactive power of SVC. The traditional control design of HVDC and SVC can improve the stability, but there may be a negative interaction between the controllers of HVDC and HVDC or HVDC and SVC. Furthermore, the power system is a strong nonlinear system, and the controller designed by a linearized model may reduce its performance. To solve these problems, this article first constructs a unified macro variable and manifold, which contains the model of HVDC and SVC. The manifold sets the deviation value of the center of inertia (COI) frequency of the two systems connected by HVDC to zero. Then, a nonlinear HVDC and SVC coordinated controller is derived based on the synergetic control theory. The global stability of the controller is proven by the Lyapunov theorem. Finally, the simulation results in a two‐area power system and a multi‐infeed system using the power systems computer aided design (PSCAD) show the effectiveness and superiority of the proposed controller. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Clonal evolutionary particle swarm optimization for congestion management and compensation scheme in power system

This paper presents computational intelligence-based technique for congestion management and compensation scheme in power systems. Firstly, a new model termed as Integrated Multilayer Artificial Neural Networks (IMLANNs) is developed to predict congested line and voltage stability index separately. Consequently, a new optimization technique termed as Clonal Evolutionary Particle Swarm Optimization (CEPSO) was developed. CEPSO is initially used to optimize the location and sizing of FACTS devices for compensation scheme. In this study, Static VAR Compensator (SVC) and Thyristor Control Static Compensator (TCSC) are the two chosen Flexible AC Transmission System (FACTS) devices used in this compensation scheme. Comparative studies have been conducted between the proposed CEPSO and traditional Particle Swarm Optimization (PSO). Results obtained by the developed IMLANNs demonstrated high accuracy with respect to the targeted output. Consequently, the proposed CEPSO implemented for single objective in single unit of SVC and TCSC has resulted superior results as compared to the traditional PSO in terms of achieving loss reduction and voltage profile improvement.

Transient Stability Assessment by Coordinated Control of SVC and TCSC with Particle Swarm Optimization

This paper aims on improving the stability of a 9 bus power system under fault condition using coordination of FACTS device. Flexible A.C. transmission system (FACTS) can be regulated reliable with faster output and can improve local power grid status with control with appropriate control strategies in very small time period. Based on that, a particle swarm optimization (PSO) algorithm was executed, to design the coordinated parameter of static VAR compensator (SVC) and Thyristor Controlled Series Capacitor (TCSC). Simulation is performed on WSCC 9-bus system in MATLAB software. When 3 phase fault is applied near to generator, frequency and rotor angle changes accordingly. With coordinated control of FACTS devices with PSO has implemented both, near to its normal condition. PSO performed in this paper was structured on identifying the values of L and C of SVC and TCSC, for superior coordination.

A Review on SVC control for power system stability with and without auxiliary controller

Since the beginning of the last century, power system stability has been recognized as a vital problem in securing system operation. Power system instability has caused many major blackouts. This paper reviewed the previous technical works consisting of various methods of optimization in controlling power system stability. The techniques presented were compared to optimize the control variables for optimization of power system stability. Power system stability enhancement has been investigated widely in literature using different ways. This paper is focusing on SVC performance for enhancing power system stability either through SVC controlled itself or SVC controlled externally by other controllers. Static VAR compensators (SVCs) are used primarily in power system for voltage control as either an end in itself or a means of achieving other objectives, such as system stabilization.The analysis on performance of the previous work such as advantages and findings of a robust method approach in each technique was included in this paper.

Optimal Placement and Dispatch of LV-SVCs to Improve Distribution Circuit Performance

In this paper, a two-stage optimization framework is proposed for optimal placement and centralized real-time control of low-voltage static var compensators (LV-SVCs) in unbalanced distribution circuits to achieve feeder level benefits namely voltage regulation and energy loss minimization. The number, locations, and the optimal real-time reactive power injections from the LV-SVCs are determined from a proposed three-phase unbalanced ac optimal power flow (ACOPF). The ACOPF is formulated as a multi-objective optimization with operating constraints written in rectangular coordinates. The resulting nonlinear nonconvex problem is solved using the predictor-corrector primal-dual interior point method. The proposed approach is scalable for application to large distribution circuits, treats the constraints of physical space limitations effectively, and can take advantage of communication capabilities of LV-SVCs for centralized real-time control. The benefits of the proposed real-time control of LV-SVCs as compared to their operation with local autonomous voltage-based distributed control is demonstrated. The results show that, the proposed approach addresses the LV-SVC placement and control problem effectively to minimize energy losses while maintaining the voltage regulation.

Voltage Frequency Control Using SVC Devices Coupled With Voltage Dependent Loads

This paper proposes a decentralized control based on static var compensator (SVC) devices to improve the frequency control of high voltage transmission systems. For a realistic structure preserving power system with voltage dependent loads, we propose a sufficient condition based on a strict Lyapunov energy function, which is utilized to design a nonlinear adaptive SVC controller. This controller only requires local bus measures and parameters. Furthermore, we also present an SVC with a conventional frequency droop controller. The performance of the two considered SVC control systems are evaluated on the well known IEEE New England 39-bus 10-machine power system and compared with conventional SVC controllers.

Enhancing voltage stability and LVRT capability of a wind-integrated power system using a fuzzy-based SVC

The static var compensator (SVC) has widespread applications in voltage regulation and stability improvement of power systems. This paper studies the SVC performance in a single machine (doubly-fed induction generator (DFIG) employed in a wind farm) infinite bus (SMIB) system. The SVC is employed to improve the voltage stability of the system and the low voltage ride-through (LVRT) capability of the wind farm. To enhance the effectiveness of the SVC, a supplementary fuzzy-based controller (FC) is proposed and is integrated into the SVC controller. The use of the proposed FC leads to the increasing the accuracy of the SVC controller that results in improving its performance in both transient and steady state. By using the proposed controller, the steady state voltage is enhanced and the maximum voltage drop under fault situations is decreased. Less voltage drop after the fault occurrence using the proposed FC results in improving the LVRT capability and makes the wind farm able to meet the grid code requirements in a larger range of load variations in the system. Using extensive simulations in MATLAB/Simulink, the effectiveness of the proposed method in improving the voltage stability and LVRT capability is validated and its effects on the performance of the DFIG-based wind turbine are studied. Three different cases are investigated in the system simulation, in which by using the proposed FC, the steady state voltage error at the load bus and the maximum voltage drop after the fault occurrence at the generator (wind farm) bus are decreased by 74.44% and 25.16% on average, respectively.