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This paper investigates an optimal methodology for mitigating low-frequency oscillation concerns in power systems. The study explores the synergistic integration of a power system stabilizer (PSS) and a flexible alternating current transmission system (FACTS) to formulate an intelligent controller. A comprehensive analysis encompasses various PSS design strategies, including lead-lag (LL), proportional-derivative-integral (PID), and fractional-order proportional-integral-derivative (FOPID) controllers. The FACTS device selected for this investigation is a static VAR compensator (SVC), highlighting the exceptional efficacy of FOPID-based PSS over alternative strategies with a power oscillation damper. The study extends its scope to encompass a comparative assessment of two distinct optimization algorithms: the moth flame optimization (MFO) and the antlion optimization (ALO). The research is conducted using a single-machine infinite bus power system (SMIB) as the case study platform. A total of four diverse test scenarios are executed under varying operating conditions. The evaluation of the developed method employs six distinct performance indices to investigate the developed controller thoroughly. The outcomes reveal that the MFO-optimized FOPID-PSS and SVC controller outperforms other control schemes. This optimized configuration demonstrates substantial improvements across all performance indices. These findings underscore the superior capabilities of the proposed approach in enhancing power system stability and performance. [ABSTRACT FROM AUTHOR]

The paper presents a ground fault location algorithm (GFLA) in double‐circuit transmission lines (DCTL) with a T‐off connection to an industrial microgrid (IMG) containing electric arc furnaces (EAF), renewable distributed generations (RDG), and static VAR compensator (SVC). The design presented utilizes the information on the current and voltage phasors of one side of the transmission lines (TL) during the fault period, and there is no need for the availability of information on the type of faulty phase(s) and even the faulty section. To find the exact location of the fault in this design, the voltage phasor equations governing the fault point in positive, negative, and zero‐sequence (PNZS) domains, the zero‐sequence current (ZSC) equation of the fault point, and the boundary condition equation of the fault point have been used. The simulation system is implemented in Simulink/MATLAB using accurate modelling of all network components. The algorithm has been tested and evaluated in different fault conditions, including various locations, phase types, phase‐to‐ground connection resistance, occurrence time, and microgrid (MG) operation modes. The successful results of various tests of the proposed design as well as the analysis of various sensitivities confirm the satisfying performance of the suggested algorithm. [ABSTRACT FROM AUTHOR]

Flexible alternating current transmission systems (FACTSs) have been widely incorporated in electric power systems in order to control system parameters. This paper proposes the modeling of four FACTS devices, using the Branch Flow Model (BF) as an optimization problem to reduce the complexity of the Newton–Raphson (NR) load flow code with FACTS devices. The devices are represented as variable impedances, as a function of a firing angle, and as voltage source converters (VSCs) located on the buses and transmission lines. This proposed model solves the problem associated with the selection of appropriate initial conditions of the parameters of each device that guarantee convergence. The model is validated by evaluating its percentage deviation with respect to the NR method, using the standard test systems, IEEE 5-bus, IEEE 14-bus, IEEE 30-bus, and IEEE 57-bus systems. [ABSTRACT FROM AUTHOR]

The importance of flexible alternating current transmission system (FACTS) devices is increasing day by day as they provide compensation for power systems. The installation of such devices solves many issues regarding the stability and power transferability of power systems. However, for optimizing the performance of FACTS devices, the location and sizes of FACTS devices must be selected very carefully. On the other side, the utilization of optimization techniques is increasing daily, as it is capable of solving nonlinear, random problems by its stochastic nature. As a result, it became a reliable tactic for solving stochastic problems almost in every aspect of our lives. Therefore, it is adopted for solving power system problems, like, FACTS devices allocation, distributed generators allocation, determining component's parameters, and more. In this paper, the optimal size and location of several FACTS devices are selected to achieve the following single objective functions separately: fuel cost minimization and power losses minimization, then combining the mentioned objective function into one multiobjective function for gross cost minimization. The power system optimized is the Institute of Electrical and Electronics Engineers 30‐bus standard system, and the FACTS devices installed are static VAR compensator, thyristor control series compensator, and thyristor‐controlled phase shifter, while the optimization is performed using different conventional and recent optimization algorithms, including a newly developed algorithm, typically Leader Walrus Optimization Algorithm "LWaOA," making a comparison among such algorithms to investigate the algorithm that possesses the best performance. The results of the optimization processes show the superiority of LWaOA. [ABSTRACT FROM AUTHOR]

This work focuses on the use of the Linear Quadratic Gaussian (LQG) technique to construct a reliable Static VAr Compensator (SVC), Thyristor Controlled Series Compensator (TCSC), and Excitation System controller for damping Subsynchronous Resonance (SSR) in a power system. There is only one quantifiable feedback signal used by the controller (generator speed deviation). It is also possible to purchase this controller in a reduced-order form. The findings of the robust control are contrasted with those of the "idealistic" full state optimal control. The LQG damping controller's regulator robustness is then strengthened by the application of Loop Transfer Recovery (LTR). Nonlinear power system simulation is used to confirm the resilience of the planned controller and demonstrates how well the regulator dampens power system oscillations. The approach dampens all torsional oscillatory modes quickly while maintaining appropriate control actions, according to simulation results. [ABSTRACT FROM AUTHOR]

The problem regarding the optimal placement and sizing of different FACTS (flexible alternating current transmission systems) in electrical distribution networks is addressed in this research by applying a master–slave optimization approach. The FACTS analyzed correspond to the unified power flow controller (UPFC), the thyristor-controlled shunt compensator (TCSC, also known as the thyristor switched capacitor, or TSC), and the static var compensator (SVC). The master stage is entrusted with defining the location and size of each FACTS device using hybrid discrete-continuous codification through the application of the black widow optimization (BWO) approach. The slave stage corresponds to the successive approximations power flow method based on the admittance grid formulation, which allows determining the expected costs of the energy losses for a one-year operation period. The numerical results in the IEEE 33-, 69-, and 85-bus grids demonstrate that the best FACTS device for locating in distribution networks is the SVC, given that, when compared to the UPFC and the TCSC, it allows for the best possible reduction in the equivalent annual investment and operating cost. A comparative analysis with the General Algebraic Modeling System software, with the aim to solve the exact mixed-integer nonlinear programming model, demonstrated the proposed BWO approach's effectiveness in determining the best location and size for the FACTS in radial distribution networks. Reductions of about 12.63 % and 13.97 % concerning the benchmark cases confirmed that the SVC is the best option for reactive power compensation in distribution grids. [ABSTRACT FROM AUTHOR]

Given the concern for maintaining voltage stability in power systems integrated with renewable power systems due to a mismatch in generation and demand, there remains a need to invoke flexible alternating current transmission system (FACTS) devices in the distribution network. The present paper deals with identifying the locations of placement of a static var compensator in an experimental IEEE 14-bus system; the voltage drop in different buses in an IEEE 14-bus system is calculated by the standard formula. The total voltage drop in the network (TVDN) is also calculated as a reference. The ranking of buses in order of decreasing voltage drop is made, and the weak buses are identified as those showing the maximum or near-maximum voltage drop for the installation of a Static Var Compensator (SVC). The optimum usable size is calculated using a Genetic Algorithm approach to optimize the installation cost. After size optimization, installing a 2 MW solar generator is considered for the weak and most potential bus, which suffers from voltage drops or power loss. Based on the generator at the weakest bus, the total power loss in the network is calculated and compared with a similar method to assess the efficiency of the proposed model. Thus, the voltage stability enhancement problem is solved by applying a Genetic algorithm (GA) to optimize SVC size and using the Total Voltage Drop in Network (TVDN) method to identify weak buses in the systems. It is found that the performance of the proposed system is comparable with another existing system. It is further observed that a gain in power loss to 6.56% is achievable by adopting the proposed strategy, and the gain is better than the other system. [ABSTRACT FROM AUTHOR]

This study presents a novel improved differential evolutionary (IDE) algorithm for optimizing reactive power management (RPM) problems. The effectiveness of IDE algorithm is tested on different unimodal and multimodal benchmark functions. The objective function of the RPM is considered as the minimization of active power losses. Initially, the power flow analysis approach is employed to detect the optimal position of flexible AC transmission system (FACTS) devices. The proposed method is used to determine the optimal value of control variables such as generator's reactive power generation, transformer tap settings, and reactive power sources. Furthermore, the efficacy of the IDE approach is compared with other promising optimization methods such as variants of differential evolution algorithm, moth flame optimization (MFO), brainstorm‐based optimization algorithm (BSOA), and particle swarm optimization (PSO) on various IEEE standard test bus (i.e., IEEE‐30, ‐57, ‐118, and ‐300) systems with active and reactive loading incorporating FACTS devices. A Static VAR compensator (SVC) for shunt compensation and a thyristor‐controlled series compensator (TCSC) for series compensation were used as FACTS devices. The proposed IDE method significantly reduces the active power loss, that is, 55.65% in IEEE 30, 39.68% in IEEE 57, 16.32% in IEEE 118, and 8.56% in IEEE 300 bus system at nominal loading. Finally, the statistical analysis such as Wilcoxon signed‐rank test (WSRT) and ANOVA test were thoroughly analysed to demonstrate the firmness and accuracy of the proposed technique. [ABSTRACT FROM AUTHOR]

The strategic intent of the African Union is to develop a "Smart Integrated African Electric Power Super Grid" driven by modern tools and advances in high-voltage direct current (HVDC) engineering and flexible alternating current technology systems (FACTS), which is central in supporting Africa's sustained economic growth and development. The southern African region, including South Africa, is beset by the critical challenges of perennial load-shedding, which impedes economic growth and aggravates unemployment. This has led to the insecurity of electricity supplies and degraded the quality of life. The parallel operation of high-voltage direct current (HVDC) and flexible AC technology systems (FACTS) controllers is gaining traction as system conditions become more complex, such as weak power networks which requires increased stability requirements, resulting in load-shedding and power outages. These adversely affect business productivity and adversely affect GDP and economic growth. Thus, the application of innovative technologies such as HVDC links can stabilize weak power systems. It is established that HVDC delivery systems reduce losses in long transmission lines transporting bulk power compared with high-voltage alternating current (HVAC) transmission lines for power wheeling. This paper evaluates the parallel operation of the Cahora Bassa 1414 km bipolar HVDC link and a weak parallel 400/330 kV alternating current (AC) link. It demonstrates the use of FACTS controllers to enhance the technical performance of an existing network, such as voltage control, and technical loss reduction. It combines an HVDC line commutated converter (LCC) and HVAC transmission lines, in hybrid notation to increase the voltage stability of the system by controlling the reactive power with a Static Var Compensator (SVC). These modern tools can increase the transmission power controllability and stability of the power network. In this study, HVDC–LCC was used with a setpoint of 1000 MW in conjunction with the 850 MVAr SVC. The results show that the technical losses were reduced by 0.24% from 84.32 MW to 60.32 MW as Apollo 275 kV SVC was utilized for voltage control. The network analysis was performed using DIgSILENT PowerFactory software that is manufactured by DIgSILENT GmbH at Gomaringen, Germany [ABSTRACT FROM AUTHOR]

Worldwide, due to the abrupt growth of population, the load demand has been rising dramatically in the last few years. This led to an increase in branch overloads, voltage deviations, and power losses. These problems may result in line outages or the occurrence of blackouts. Flexible AC transmission system (FACTS) devices can be installed in the power system to ensure increased power flow capability and flexible voltage control to address these issues. In this paper, one of the most used FACTS is utilised. It is called Static VAR Compensator (SVC). This controller is one of the most commonly used shunt FACTS controllers due to its low cost in comparison to others, ease of operation, and integration into the power grid. Two Optimization algorithms are combined to form a hybrid optimization approach: Cuckoo Search (CS) and Antlion Optimization (ALO). This hybrid approach employs the exploration of ALO to adjust the optimum allocation and size for SVCs in the power system. This study proposes the IEEE 57 bus scheme as a fairly large structure, with the 50 and 41 branch outages considered the worst-case scenarios for line outages in this system. The simulation results show that the proposed methodology balances exploring the research space and exploiting the best existing solutions compared to some of the other introduced approaches in the literature. [ABSTRACT FROM AUTHOR]

A constant worldwide growing load stress over a power system compelled the practice of a reactive power injection to ensure an efficient power network. For this purpose, multiple technologies exist in the knowledge market out of which this paper emphasizes the usage of the flexible alternating current transmission system (FACTS) and presents a comparative study of the static var compensator (SVC) with the static synchronous compensator (STATCOM), inducted in a real electric substation. The aim is to improve the power factor (PF) and power quality and to encounter reliably extreme conditions. A 220 kV electric substation was opted for the analysis, and both the static and dynamic conditions were observed with the help of a power system analysis tool termed PowerFactory-DIgSILENT. Multiple aspects were investigated via software simulations to assess the performance of the aforementioned FACTS devices, such as the voltage profile evaluation via the load flow analysis method (LFA), the harmonic response via the power quality and harmonic analysis tool, and the short-circuit response via the RMS simulation tool. The outcomes were verified and compared with permissible values included in the universal standards, such as IEC and IEEE. The superiority of the STATCOM over the SVC was proven in light of the simulative results. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the Static Var Compensators (SVC) on distance relay protection when connected to the sub-transmission network of the Nigerian 132-kV grid system is investigated. This is carried out by monitoring the error margin of the fault locator associated with the distance protective relays when SVC is connected to the transmission line. The location of the SVC is selected such that there is a common primary source of power to the subtransmission network (Ikorodu-Sagamu 132-kV transmission line) and the SVC, which is a shunt-connected device located on Ikorodu 132-kV bus. The fault is simulated at 33.6 km and 60.4 km respectively from the Ikorodu 132-kV sub-station in MATLAB/ Simulink model and the simulation results obtained are used to investigate the influence of SVC on distance protective relay when connected to the 132-kV power transmission line. The results of the line faults are obtained with respect to earth for both zones one (1) and two (2) when SVC is connected and disconnected for all shunt type of faults. Thus, indicating under-reach and overreach characteristics of the distance relay, when the SVC is connected and disconnected, while the transmission line protection showed no under-reach or over-reach characteristics for line-toline fault for both zones with the SVC connected or disconnected. The results of this study show that though SVCs improve the quality of power to consumers, there is a tendency for underreach and over-reach characteristics of the protective relay to be displayed when the relays are disconnected and connected, which introduces error margins to the fault locator in distance protective relays. Therefore, more detailed dynamic simulations are recommended for reducing the error margin. [ABSTRACT FROM AUTHOR]

The goal of multi-criteria decision making (MCDM) is to select the most appropriate of the alternatives by evaluating many conflicting criteria together. MCDM methods are widely available in the literature and have been used in various energy problems. The key problems studied in electrical power systems in recent years have included voltage instability and voltage collapse. Different flexible alternating current transmission systems (FACTS) equipment has been used for this purpose for decades, increasing voltage stability while enhancing system efficiency, reliability and quality of supply, and offering environmental benefits. Finding the best locations for these devices in terms of voltage stability in actual electrical networks poses a serious problem. Many criteria should be considered when determining the most suitable location for the controller. The aim of this paper is to provide a comparative analysis of MCDM techniques to be used for optimal location of a static VAR compensator (SVC) device in terms of voltage stability. The ideal location can be determined by means of sorting according to priority criteria. The proposed approach was carried out using the Power System Analysis Toolbox (PSAT) in MATLAB in the IEEE 14-bus test system. Using ten different MCDM methods, the most appropriate locations were compared among themselves and a single ranking list was obtained, integrated with the Borda count method, which is a data fusion technique. The application results showed that the methods used are consistent among themselves. It was revealed that the integrated model was an appropriate method that could be used for optimal location selection, providing reliable and satisfactory results to power system planners. [ABSTRACT FROM AUTHOR]

This paper presents the application of Flexible Alternating Current Transmission System (FACTS) devices based on heuristic algorithms in power systems. The work proposes the Autonomous Groups Particle Swarm Optimization (AGPSO) approach for the optimal placement and sizing of the Static Var Compensator (SVC) to minimize the total active power losses in transmission lines. A comparative study is conducted with other heuristic optimization algorithms such as Particle Swarm Optimization (PSO), Timevarying Acceleration Coefficients PSO (TACPSO), Improved PSO (IPSO), Modified PSO (MPSO), and Moth-Flam Optimization (MFO) algorithms to confirm the efficacy of the proposed algorithm. Computer simulations have been carried out on MATLAB with the MATPOWER additional package to evaluate the performance of the AGPSO algorithm on the IEEE 14 and 30 bus systems. The simulation results show that the proposed algorithm offers the best performance among all algorithms with the lowest active power losses and the highest convergence rate. [ABSTRACT FROM AUTHOR]

This study introduces a techno-economic planning strategy of reactive power (VAr) in power transmission systems. This planning strategy primarily has been focused on reactive power planning (RPP) through operating cost minimisation ensuring cost-oriented system security. The objective function (operating cost) is blended with four different components viz. cost due to real power loss, VAr generation cost, additional VAr compensation devices cost and line charging cost. FACTS (flexible AC transmission system) devices are installed at weak positions through different echelons to improve the system voltage stability. The authors also implemented the probabilistic hybridisation of crow search algorithm and JAYA to find out the optimal set of controlling parameters related to VAr. Finally, a sharp and minute analysis of the results has been done to validate the proposed strategy under multi-loading conditions. To understand the efficiency and efficacy the code profiling and simulation has been rendered on IEEE 30 bus and UPSEB 75 bus test system. [ABSTRACT FROM AUTHOR]

This study introduces a techno‐economic planning strategy of reactive power (VAr) in power transmission systems. This planning strategy primarily has been focused on reactive power planning (RPP) through operating cost minimisation ensuring cost‐oriented system security. The objective function (operating cost) is blended with four different components viz. cost due to real power loss, VAr generation cost, additional VAr compensation devices cost and line charging cost. FACTS (flexible AC transmission system) devices are installed at weak positions through different echelons to improve the system voltage stability. The authors also implemented the probabilistic hybridisation of crow search algorithm and JAYA to find out the optimal set of controlling parameters related to VAr. Finally, a sharp and minute analysis of the results has been done to validate the proposed strategy under multi‐loading conditions. To understand the efficiency and efficacy the code profiling and simulation has been rendered on IEEE 30 bus and UPSEB 75 bus test system. [ABSTRACT FROM AUTHOR]

To relieve congestion due to open‐access feature in competitive power system framework, utilities plan flexible alternating current transmission systems (FACTS), ensuring improved utilization and performance of the transmission infrastructure. However, high‐investment cost restricts implementation to single type of FACTS' planning in a time. Therefore, successive planning of another FACTS to delay transmission expansion results in multi‐type FACTS planning. Consequently, to optimise performance, subsequent planning must coordinate with existing FACTS. The main objective of this study is to implement coordination of multi‐type FACTS for available transfer capability (ATC) enhancement. A hybrid real power flow performance index (PI) and particle swarm optimisation (PSO), coordinate thyristor control series compensator (TCSC) in the first planning horizon with static synchronous series compensator (SSSC) and unified power flow controller (UPFC), in the second horizon. The PI–PSO‐based multi‐type FACTS coordination improves ATC of multilateral power transfers in a standard 9‐buses test network. Results show that multi‐type FACTS achieved higher ATC; such that enhanced ATC by TCSC–SSSC ranges between 8.06–69.34% while the TCSC–UPFC ranges between 11.85–71.59% for various power transfer transactions. A comparison of the three coordination schemes shows that the scheme with more decision parameters provides superior loadability and transfer capability improvement. [ABSTRACT FROM AUTHOR]

Within substations installed with flexible ac transmission systems, the magnetic flux leakage (MFL) generated by air core reactors in static var compensator (SVC) can be very high. To reduce the influence of the high magnetic field, an optimal suppression method is selected based on fuzzy comprehensive evaluation. First, a series of onsite measurements are performed around the reactors in the SVC. From the measurement results, the low-voltage cables, dc system, grounding grid, and magnetic flux density around the air core reactors are seriously affected by the MFL generated by the air core reactors with currents of a few kiloamperes. Then, according to the actual parameters of the air core reactors, a three-dimensional simulation model is constructed using the finite-element method (FEM) to calculate the magnetic flux density and some parameters related to the magnetic field. Moreover, four different suppression methods are proposed to suppress the MFL influence. Due to the multiple aspects affected by MFL, it is always difficult to make a quantitative comparison for the suppression methods based on previous research. For this reason, a fuzzy comprehensive evaluation method based on a linear evaluation model is proposed to quantitatively compare the suppression methods by using the suppression effect value δ. In a comparison of different suppression methods, the aluminum plate shielding with proper parameters has prove to be an optimal method for achieving a comprehensive suppression effect. The modeling and evaluation methods presented in this article are both valuable to solve the complex MFL influence problem in different SVC-based substations. [ABSTRACT FROM AUTHOR]

In this study, a maiden application of cascade proportional–integral–derivative with filter (PIDF) and one plus fractional-order derivative (1+FOD), i.e. PIDF(1+FOD) controller is proposed for the load frequency control mechanism. The main purpose of the cascade and fractional order controller is to increase the degree of freedom and reject the disturbances faster. A novel attempt has also been made to model a static synchronous series compensator (SSSC) with AC tie-line and HVDC tie-line. Here SSSC and HVDC tie-line are used to regulate and increase the power transfer capabilities between interconnected areas. Furthermore stored energy in the HVDC tie-line is utilised to improve the system dynamics by inertia emulation control strategy. An evolutionary salp swarm algorithm-based optimisation technique is adopted to optimise control parameters. The performance of the proposed controller is tested on a two-area hydro-thermal interconnected power system in deregulated environment. First, the effectiveness AC–DC-SSSC tie line is shown over AC-SSSC and alone AC tie-line with proposed PIDF(1+FOD) controller followed by the supremacy of proposed PIDF(1+FOD) over classical controllers. Finally, sensitivity is analysed by variation in system parameters, which shows the robustness of the proposed controller. [ABSTRACT FROM AUTHOR]

In this study, a maiden application of cascade proportional–integral–derivative with filter (PIDF) and one plus fractional‐order derivative (1+FOD), i.e. PIDF(1+FOD) controller is proposed for the load frequency control mechanism. The main purpose of the cascade and fractional order controller is to increase the degree of freedom and reject the disturbances faster. A novel attempt has also been made to model a static synchronous series compensator (SSSC) with AC tie‐line and HVDC tie‐line. Here SSSC and HVDC tie‐line are used to regulate and increase the power transfer capabilities between interconnected areas. Furthermore stored energy in the HVDC tie‐line is utilised to improve the system dynamics by inertia emulation control strategy. An evolutionary salp swarm algorithm‐based optimisation technique is adopted to optimise control parameters. The performance of the proposed controller is tested on a two‐area hydro‐thermal interconnected power system in deregulated environment. First, the effectiveness AC–DC‐SSSC tie line is shown over AC‐SSSC and alone AC tie‐line with proposed PIDF(1+FOD) controller followed by the supremacy of proposed PIDF(1+FOD) over classical controllers. Finally, sensitivity is analysed by variation in system parameters, which shows the robustness of the proposed controller. [ABSTRACT FROM AUTHOR]

Flexible AC transmission systems (FACTS) technology is widely adopted and utilized to maintain the performance of power systems. However, the improvements of power system performance achieved by FACTS devices depend on the right sizing and allocation of such devices. For technical and economic considerations, a FACTS device's location and size should be selected very carefully in order to maximize its benefits to the power system. In this paper, the sizing and location of a static VAR compensator (SVC) are optimally determined using a new optimization technique called lightning attachment procedure optimization (LAPO). The optimal allocation of the SVC is determined regarding the improvement of voltage deviation index and the reduction of total active power losses. The system is optimized in two cases: once without SVC installation in order to find out the optimal settings of the system that achieve the objective functions, and another time with SVC installation to determine its optimum sizes and locations by which the required objective functions are achieved. Then the system performance is analyzed after optimization with and without SVC devices to show the impact of the optimum sizing and location of the SVC on the system. The study is validated using the standard IEEE 30-bus system, while the developed LAPO is performed by MATLAB M-Files and the system performance analysis in different cases is performed by NEPLAN software. [ABSTRACT FROM AUTHOR]

Flexible AC Transmission Systems (FACTS) present a decision to issue trouble relief for over-extended electric power transmission lines as a result of optimal power flow (OPF) by controlling. To keep away from conventional impacts among a few gadgets placed in a similar grid, an organized control is fundamental. To defeat the issues which happen in optimal power flow to actualize the cross difference progression and coordination inspects strategy, a supervisory controller giving difference progression power flow with numerous destinations is acquired for avoiding congestion, it gives secure transmission and farthest point dynamic power misfortunes. There is no information on gadgets that have been defined in this systematic control of Thyristor controlled series capacitor (TCSC) and Thyristor controlled phase shifting Transformer (TCPST), static VAR compensator (SVC), all of these compensators providing efficient improvements and situations are described. Different optimization techniques are used as a part of the character to deal with the problem of OPF. In some experimental works, the upgrade method is used for finding out all of the fuel costs or the environmental pollution that occurs during the generation of energy. However, in some further research actions, FACTS controlled devices are used to develop the flow of electricity without considering the cost of electricity generation. While a specific end goal of using the FACTS control devices is to help optimize the congestion in the power system, it also aggregates the power loss which enhances the load capacity of the structure. The FACTS and its practical limitations are executed into the IEEE 30-bus test power framework and customized utilizing the Cross Difference Progression and Coordination Examining (CDP&CE) algorithm with MATLAB and the outcomes are given. Here, IoT-based data analytics is defined as the process, which is used to examine varied data from the bus system using Principal Component Analysis (PCA) method, the results of which help to take the necessary decisions. The effect of FACTS gadgets is implemented on standard IEEE-30 transmission framework with supporting numerical outcomes by utilizing MATLAB Software. [ABSTRACT FROM AUTHOR]

Optimal reactive power dispatch is one of the key factors to attain cost-effective and stable functioning of power system. It is a complicated non-linear optimization issue with a combination of discrete and continuous control variables. Due to this complex feature of optimal reactive power dispatch, optimization technique has become an efficient method to solve this problem. In this work, Kinetic Gas Molecule Optimization algorithm with Pareto optimality is proposed for solving multi-objective optimal reactive power dispatch problem. The presentation of Kinetic Gas Molecule Optimization is improved by computing inertia weight and acceleration coefficients dynamically rather than a fixed value. Because of this reason, the searching capability of the particles in each iteration is improved. However, to improve the power system performance in optimal reactive power dispatch scenario, additional flexible AC transmission system devices like static VAR compensator, thyristor-controlled series compensator, and unified power flow controller are introduced to provide stable results when compared to conventional output because flexible AC transmission system devices are capable of controlling the flow of real power and reactive power. These details are implemented and tested on IEEE 30-bus test system with various objectives. The performance of proposed method is validated from MATLAB, which shows the value of power loss as 4.3583 and voltage deviation as 0.26499 with cost of US$469.6417 per MVAR, which shows considerably superior results when compared with implemented particle swarm optimization results. The proposed method provides an efficient result for solving multi-objective optimal reactive power dispatch issues. [ABSTRACT FROM AUTHOR]

The concern for ever-increasing demand for electricity, progressive depletion of fossil fuels, reduction in carbon footprint, improved infrastructure reliability, etc. have encouraged the power utility companies to adopt renewable energy sources in conventional power systems. The enhanced penetration of non-dispatchable renewable energy sources such as solar photovoltaic (PV) and wind energy into existing distribution and transmission networks had led to various issues of concern regarding system voltage stability. This paper presents the important issues such as voltage stability based optimum locations and sizing of distributed generation (DG) units, voltage stability assessment, and improvement techniques. The impact of power system devices such as fixed capacitors, flexible AC transmission system (FACTS), and energy storage system (ESS) on voltage stability of transmission and distribution networks are also investigated. The review results provide a comprehensive background for the voltage stability investigation in non-dispatchable renewable integrated power systems with major outcomes and findings of future research work in the field of power system stability. [ABSTRACT FROM AUTHOR]

Low-frequency electromechanical oscillations damping is powerfully crucial in power system operation. In order to fulfill this requirement, power oscillation damping (POD) controllers are installed in synchronous generators and flexible alternating current transmission system devices. These controllers can have either a conventional fixed structure composed by stages of gain and phase compensation or a multi-band modern structure (PSS4B) composed by three bands that correspond to a specific frequency range (low, intermediate and high frequency). In the PSS4B structure, each band consists of two branches based on differential filters (with a gain, lead–lag blocks and a hybrid block). This paper investigates the application of PSS4B as a POD controller for the static VAR compensator (PSS4B-SVC-POD) to damp oscillations in multi-machine power systems. The proposed PSS4B-SVC-POD and power system stabilizers (fitted on generators) are simultaneously designed through an optimization approach aiming at maximizing the closed-loop damping ratio. Modal analysis, frequency responses and time simulations for the well-known two-area four-generator power system show the good performance of the proposed controller fitted on static VAR compensator. [ABSTRACT FROM AUTHOR]

Power quality is often defined as the electrical network's or the grid's capability to deliver a clean and stable power supply. Flexible AC transmission systems (FACTS) devices consist of power electronics circuits that's depend on the thyristor for controlling active and reactive power flows and to maintain the voltage within the allowable limits in normal and abnormal operating conditions. Static Var Compensation (SVC) is one of the most important FACTS devices, that's combined between shunt capacitor and shunt reactor, that's connect with the system by control setting. The control of reactive power by SVC module is depending on firing angle of thyristors. The shunt capacitor module can be called thyristor switched capacitors (TSC) and thyristor-controlled reactors (TCR), that's provide harmonic filters and/or dynamic shunt compensation. TSC operates with series bi-directional thyristor and a damping reactor to prevent the shunt resonance, the thyristors are used to control the capacitor to operate at the required value. TCR operates with series thyristor switch for control. SVC is easy and more accurate to operate with the medium voltage. SVC can be connected with the extra high voltage system via step-down transformer. This paper discusses the SVC to be uses to improve the power system quality, by adding the reactive power to the system. Also, this paper discusses the SVC control by using the MATLAB/Simulink software to discuss the step operation for the SVC with the power system. [ABSTRACT FROM AUTHOR]

Hydro‐Québec has identified wide‐area control system as a key initiative able to significantly increase the voltage stability of its grid. In this context, an innovative project for wide‐area and local voltage control of shunt compensators was initiated. Its main objective is to implement a closed‐loop control system on Hydro‐Québec's network to optimise the reactive power support from the dynamic shunt compensators. The outcome of this project is the 'global and local control of compensators' (GLCCs) system which is based on synchrophasor technology and intelligent electronics devices. Applied to each shunt compensator of Hydro‐Québec's network, this robust voltage control system measures voltage variations in the load area and adjusts the operation set point of each shunt compensator accordingly, thus avoiding voltage collapse resulting from extreme contingencies. The GLCC control solution was intensively tested in simulation using PSSE software. Moreover, a pilot project was commissioned on a test bench replica of the system and also tested in real time using Hydro‐Québec's Hypersim digital simulator. Field tests of the GLCC were conducted on a −230/ + 660 MVars static vars compensator. The results of this pilot project were deemed conclusive and the deployment of the new voltage control system has been initiated by Hydro‐Québec. [ABSTRACT FROM AUTHOR]

Development of appropriate load flow model of Flexible AC Transmission System (FACTS) devices is an important issue for proper planning, control, and protection of power system. Holomorphic Embedding Load-Flow Method (HELM) is a novel technique for solving load flow nonlinear equations which overcomes the numerical problems faced by traditional iterative techniques. In order to evaluate the effects of FACTS devices in load flow problem by HELM technique, it is necessary to develop HELM modeling of these devices. This paper presents HELM modeling of Thyristor-based FACTS controllers, i.e., Static Var Compensator (SVC), Thyristor Controlled Switched Capacitor (TCSC), Thyristor Controlled Voltage Regulator (TCVR), and Thyristor Controlled Phase Angle Regulator (TCPAR). In this modeling, white germ solution is investigated along with recursive formula and controlling FACTS devices operation bounds. [ABSTRACT FROM PUBLISHER]

The static VAR generator (SVG) is an important device in flexible AC transmission systems (FACTS) for the development of smart grids. Based on the basis principle of SVG and instantaneous reactive power theory, the conventional ip-iq and dq methods have a certain error when the three phase voltages are unbalanced. In this paper, the current detection algorithm is improved in cases of three-phase power asymmetry by using the fundamental positive-sequence reactive current instead of the voltage as the input of phase locked loop (PLL). So the problems caused by unbalanced three-phase voltages could be avoided. In addition, a moving average filter is designed to improve the performance of the detection accuracy and dynamic response. Experiments verify the correctness and effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

This study presents a novel interfacing setup for testing and validating wide‐area monitoring and control (WAMC) techniques used in smart grids. The main purpose of this study is to provide a realistic approach for conducting WAMC studies. In here, a wide‐area controller (WAC) for a flexible AC transmission system (FACTS) device is implemented. The measurements for the WAC are collected using phasor measurements units (PMUs). Three main segments are being interfaced in this study. First, the real‐power grid, the local area controller of the actual FACTS device, and the PMUs are simulated using real‐time digital simulator. This simulation represents the central simulation and is interfaced with the WAC, which is realised using a MATLAB‐based program. This interface represents a novel software‐in‐the‐loop (SIL) scheme. On the other hand, an actual FACTS device is designed and interfaced to the central simulation via hardware‐in‐the‐loop (HIL) scheme. This SIL and HIL combination makes the experimental testbed more realistic and closer to the industrial standard. Various tests are conducted to examine the performance of the developed testbed. [ABSTRACT FROM AUTHOR]

Based on cascaded ac–ac converter with controllable phase and amplitude (ACCPA), a novel π model ACCPA was proposed for power flow control, whose output voltage phase and amplitude can be regulated, respectively, and simultaneously with respect to the input voltage. Single-phase π model ACCPA comprises a buck-type ac unit, a third harmonic trap and a boost-type ac converter. Compared with single-phase cascaded ACCPA, it has a more simplified structure by dispensing with the LC output filter of the buck-type ac converter, and can adopt the same two-stage duty-cycle modulation. The buck-type ac unit regulates the phase of output voltage and the boost-type ac converter does the amplitude. By utilizing impedance compensation with capacitance in single-phase π model ACCPA, it is effective to counteract or reduce the lag effect which is put on fundamental voltage by line impedance of third harmonic trap and inductance. Three-phase π model ACCPA comprises three buck-type ac units and a three-phase boost-type ac converter, it not only dispenses with three LC output filters, but also does three third harmonic traps, so it has simple structure. Experimental results verified the feasibility of π model ACCPA and the correctness of its theory. [ABSTRACT FROM PUBLISHER]

Static synchronous compensator (STATCOM), a shunt type flexible AC transmission system device, is used to control the voltage at different locations within a power system by absorbing/injecting reactive power. The dynamic control action associated with the operation of STATCOM in both capacitive and inductive modes is the reason for varying system condition and failure of different relaying schemes. Directional relaying is affected by the reactive current contributed by STATCOM in wide range of inductive to capacitive mode of operation. Further, single pole tripping (SPT) condition during STATCOM operation leads to mal‐function of the directional element due to phase change in sequence components of voltage and current. In this study, directional relaying is addressed for different types of faults in the presence of STATCOM connected at different locations during single phase auto reclosing period. Proposed directional relaying technique is based on the phase angle between positive sequence fault and pre‐fault apparent powers. Performance of the proposed scheme has been investigated for different types of faults for single and double circuit lines during SPT using simulated data of different power networks using PSCAD/EMTDC software. A comparative study is also carried out to verify the performance of the proposed scheme for different STATCOM operating conditions. [ABSTRACT FROM AUTHOR]

This study investigates the impact of different flexible AC transmission system (FACTS) devices on critical power quality (PQ) phenomena including voltage sags, harmonics and unbalance from the perspective of both mitigation effect and potential negative impact. The FACTS devices, including static VAR compensator, static compensator (STATCOM) and dynamic voltage restorers, are modelled in commercially available software PowerFactory/DIgSILENT to study their impacts on the critical PQ phenomena. Two control strategies, voltage regulation and reactive power compensation, are considered for STATCOM. For DVR, a PI‐controller is developed for the purpose of voltage sag mitigation. The merit of the proposed controller is presented by the dynamic response of during fault voltage and the capability of post‐fault voltage recovery. The study is carried out on a large‐scale generic distribution network. The impact of various devices on PQ phenomena is assessed using appropriate evaluation methodologies, and the results obtained with and without mitigation are presented and compared using heatmaps. [ABSTRACT FROM AUTHOR]

Catastrophic circumstances and equipment failures continue to occur due to Ferroresonance even though this phenomenon has been extensively investigated since, many years ago. This study enhances mitigation of Ferroresonance by means of Flexible AC Transmission System. Static var compensator is used to suppress Ferroresonance along with controlling voltage and reactive power in the network. Manitoba Hydro 230 kV electrical network has experienced Ferroresonant states several times. In this paper, by means of PSCAD/EMTDC simulation software, Ferroresonant states are recognized and analyzed in Manitoba Hydro network. Ferroresonant states are classified in adequate modes by Ferroresonance detection tools. Power and control circuit of SVC is designed and Ferroresonant states are examined in presence of SVC. [ABSTRACT FROM AUTHOR]

This paper proposes the design of auxiliary-coordinated controller for static VAR compensator (SVC) and thyristor-controlled series capacitor (TCSC) devices by adaptive fuzzy optimized technique for oscillation damping in multimachine power systems. The performance of the coordinated control of SVC and TCSC devices based on feedforward adaptive neuro fuzzy inference system (F-ANFIS) is compared with that of the adaptive neuro fuzzy inference system (ANFIS) structure based on recurrent adaptive neuro fuzzy inference system (R-ANFIS) network architecture. The objective of the coordinated controller design is to tune the parameters of SVC and TCSC fuzzy lead lag compensator simultaneously to minimize the deviation of rotor angle and rotor speed of the generators. The performance of the system is enhanced by optimally tuning the membership functions of fuzzy lead lag controller parameter of the flexible AC transmission system (FACTS) by R-ANFIS controller. The training data for F-ANFIS and R-ANFIS are generated by conventional linear control technique under various operating conditions. The offline trained controller tunes the parameter of lead lag controller in online. The oscillation damping ability of the system is analyzed for three-machine test system by calculating the standard deviation and cost function. The superior performance of R-ANFIS controller is compared with various particle swarm optimization-based feedforward ANFIS controllers available in literature. [ABSTRACT FROM AUTHOR]

Increasing maximum power system loadability while maintaining bus voltages and line loadings constraints by flexible AC transmission system (FACTS) devices is one of the main issues in power system studies. One of the shunt FACTS devices widely used in power system is static var compensator (SVC). Its performance on power system is highly dependent on its number, location and operating point. This study presents a two‐level procedure to find optimal number, locations, and operating points of SVCs in a power system. At the first level, the goal is to maximise loadability of the power system. At this level, by using a method based on iterative process, applying SVCs to the power system, and increasing load factor, the optimisation algorithm seeks to find locations and operating points of SVCs that fulfil bus voltages and line loading constraints. This process continues until the increase in the number of SVCs does not lead to an increase in loadability. At the second level and for a certain number of SVCs, power system losses, total voltage deviations (TVD), and SVC installation cost are minimised at specific loadability. In this study, hybrid imperialist competitive algorithm and genetic algorithm (HICAGA) have been used for optimisation. [ABSTRACT FROM AUTHOR]

This study presents an adaptive differential evolution (DE) algorithm to allocate the thyristor‐controlled series compensator (TCSC) incorporated with the reactive power management problem. In addition, a dynamic updating is applied for scaling and penalty factors to enhance the performance of the multi‐objective DE algorithm. During the selection of the best candidate lines for efficient allocation of TCSC devices, three situations are considered for excluded transmission lines. These situations are the lines connected between two generating units; lines connected through transformers and the lines of low losses. The considered multi‐objective function compromises between reducing power losses, improving voltage profile, reducing reactive power losses, reducing TCSC cost and reducing number of flexible alternating current transmission systems units. The optimal siting and sizing of TCSC is defined for normal and emergency operating conditions. The proposed procedure is employed for IEEE 9‐bus and IEEE 30‐bus test systems in addition to western delta network as a real part of the Egyptian network. Four case studies are considered for each test system to represent normal and abnormal operating conditions. Results clearly indicate the effectiveness of the adaptive DE algorithm to allocate perfectly the TCSC to enhance the system performance. [ABSTRACT FROM AUTHOR]

This study presents gravitational search algorithm (GSA)-based optimisation technique for the optimum coordination of multi-type flexible AC transmission system (FACTS) devices with the existing reactive power sources present in a connected power network. Three types of FACTS devices: namely, unified power flow controller, static var compensator and thyristor controlled series capacitor are used in the present problem and IEEE-30 and IEEE-57 bus systems are taken as standard test systems. The existing reactive power sources are reactive generations of the generators and transformer tap setting arrangements. The main objective of the present study is to reduce active power loss, system operating cost including the cost of FACTS devices and congestion in transmission network. The result obtained with the proposed GSA-based approach is compared with the results obtained by genetic algorithm, differential evolution and particle swarm optimisation techniques. It is observed that by optimal placement of FACTS devices along with the optimal setting of the transformer tap arrangements and control of reactive generations of the generators line loss, system operating cost and transmission congestion is reduced significantly by the GSA-based method compared with other methods. [ABSTRACT FROM AUTHOR]

The efficient operation of the present day power system is an important issue to satisfy the customer needs. To improve the performance of the existing power system, the flexible alternating current transmission system (FACTS) devices have been attracted by an engineering community with the expertise in power system. This article proposes the self-adaptive firefly algorithm (SAFA) for placement of FACTS devices, which identifies the appropriate type, best possible locations and optimal parameters of FACTS devices. Static var compensator, thyristor controlled series compensator and unified power flow controller are considers as FACTS devices for their placement. The objectives are to improve the power system performance by placement of FACTS devices through minimising real power loss, improving voltage profile and enhancing the voltage stability. Effectiveness of the proposed SAFA is tested on standard IEEE 30 and IEEE 57 bus systems with different objectives. The results are compared with other approaches, which clearly indicate the effectiveness and usefulness of the proposed method. [ABSTRACT FROM AUTHOR]

This study presents gravitational search algorithm (GSA)‐based optimisation technique for the optimum co‐ordination of multi‐type flexible AC transmission system (FACTS) devices with the existing reactive power sources present in a connected power network. Three types of FACTS devices: namely, unified power flow controller, static var compensator and thyristor controlled series capacitor are used in the present problem and IEEE‐30 and IEEE‐57 bus systems are taken as standard test systems. The existing reactive power sources are reactive generations of the generators and transformer tap setting arrangements. The main objective of the present study is to reduce active power loss, system operating cost including the cost of FACTS devices and congestion in transmission network. The result obtained with the proposed GSA‐based approach is compared with the results obtained by genetic algorithm, differential evolution and particle swarm optimisation techniques. It is observed that by optimal placement of FACTS devices along with the optimal setting of the transformer tap arrangements and control of reactive generations of the generators line loss, system operating cost and transmission congestion is reduced significantly by the GSA‐based method compared with other methods. [ABSTRACT FROM AUTHOR]

The efficient operation of the present day power system is an important issue to satisfy the customer needs. To improve the performance of the existing power system, the flexible alternating current transmission system (FACTS) devices have been attracted by an engineering community with the expertise in power system. This article proposes the self‐adaptive firefly algorithm (SAFA) for placement of FACTS devices, which identifies the appropriate type, best possible locations and optimal parameters of FACTS devices. Static var compensator, thyristor controlled series compensator and unified power flow controller are considers as FACTS devices for their placement. The objectives are to improve the power system performance by placement of FACTS devices through minimising real power loss, improving voltage profile and enhancing the voltage stability. Effectiveness of the proposed SAFA is tested on standard IEEE 30 and IEEE 57 bus systems with different objectives. The results are compared with other approaches, which clearly indicate the effectiveness and usefulness of the proposed method. [ABSTRACT FROM AUTHOR]

In this study, power system stabiliser (PSS), static VAR compensator (SVC), and thyristor controlled series capacitor (TCSC) controllers are simultaneously used to increase the stability and damping of the oscillations of a multi‐machine power system. By SVC, the transferrable power in the steady state can be increased and the voltage profile can be controlled along the line. TCSC can regulate line impedance and therefore, increase the transferred power of the system. PSS is added to excitation system to enhance the damping of electric power system during low frequency oscillations. SVC, TCSC, and PSS can combine with each other for further damping and stability; therefore, their coordination is very important. Then, adaptive velocity update relaxation particle swarm optimisation algorithm is used to optimise the parameters of PSS, SVC, and TCSC simultaneous controllers. The robustness of the proposed algorithm has been tested on 16‐machine 68‐bus power system. [ABSTRACT FROM AUTHOR]

In order to increase the power transfer and providing the optimum utilisation of the power system capability, application of flexible alternating current transmission system (FACTS) devices technology, such as static synchronous compensator (STATCOM), has been attracted, in recent years. However, the STATCOM changes the voltage and current of the power system that disturb the operation of the impedance‐based synchronous generator loss of excitation (LOE) protection. Then, this study proposes a new flux‐based LOE protection method, in the presence of STATCOM, that is based on the local variation of the flux linkage of the generator available at the location of relay. The mentioned relay is independent of other generator protection relays without any coordination. In order to show the satisfying operation of the proposed method, some simulations have been carried out in the Matlab/Simulink software. A single‐machine infinite bus and a three‐machine infinite bus systems have been used in simulations. The results show that the presence of STATCOM has no important effect on the performance of proposed relay opposite to a negative offset relay with two protective zones (the widely used impedance method) which is affected by STATCOM operation. [ABSTRACT FROM AUTHOR]

This paper first presents a step‐by‐step tutorial on modal analysis of a doubly‐fed induction generator (DFIG)‐based series compensated wind farm. The model of the system includes a wind turbine aerodynamics, a sixth‐order order induction generator, a second‐order two‐mass shaft system, a fourth‐order order series compensated transmission line, an eighth‐order rotor‐side converter (RSC) and grid‐side converter (GSC) controllers, and a first‐order DC‐link model. Then, using modal analysis and time‐domain simulations, it is shown that a fixed‐series compensated DFIG is highly unstable due to the sub‐synchronous resonance (SSR) mode. In order to damp the SSR mode, the wind farm is interfaced with the gate‐controlled series capacitor (GCSC) ‐ which is a new series flexible AC transmission system (FACTS) device. A SSR damping controller (SSRDC) is designed for the GCSC using residue‐based analysis and root locus diagrams, and an effective input control signal (ICS) to the SSRDC is identified in order to simultaneously increase damping of both the SSR and super‐synchronous (SupSR) modes. The IEEE first benchmark model on SSR is adapted with an integrated DFIG‐based wind farm to perform studies. Matlab/Simulink is used as a tool for designing process, and PSCAD/EMTDC is used for time‐domain simulations. [ABSTRACT FROM AUTHOR]

Flexible AC transmission system devices provide the opportunity to improve the usage of the current transmission facilities by controlling network flows and nodal voltages. The optimal steady‐state settings of these devices can be determined using optimal power flow calculations. However, this requires knowledge of the system parameters, generation settings and loads. A two‐stage regression‐based control scheme is proposed to determine the optimal settings of thyristor‐controlled series compensators (TCSCs) with the objective to optimally utilise the current transmission system in the presence of renewable energy resources. A regression function describing the relationship between a set of key measurements and the optimal device settings is determined in the offline simulation. This function is then used to calculate the optimal device settings by only receiving the information from a limited number of key measurements without solving the OPF problem in the online operation. Studies are carried out with TCSCs in three‐test systems, the IEEE 14‐bus system, a 28‐bus system and the IEEE 118‐bus system. The simulation results with one, two and four TCSCs are presented, illustrating the performance of the proposed regression‐based control scheme. [ABSTRACT FROM AUTHOR]

Voltage-sourced converter (VSC)-based static synchronous compensators (STATCOMs) are used for voltage regulation in transmission and distribution systems. Unlike PWM-controlled STATCOMs, angle-controlled STATCOMs are switched at line frequency to limit the system losses. In recent years, angle-controlled STATCOMs have been deployed by utilities for the purpose of transmission system voltage regulation, voltage stability improvement, and increasing operational functionality. Despite the superior feature on voltage waveform quality and efficiency, the practical angle-controlled STATCOMs suffer from the over-current (and trips) and possible saturation of the interfacing transformers caused by negative sequence current during unbalanced conditions and faults in the utility. This paper specifically proposes a control structure to improve the angle-controlled STATCOMs performance under unbalanced conditions and faults. The main improvement is a substantial decrease in the negative sequence current and dc-link voltage oscillations under power system faults by the proposed control. This eliminates the need to redesign the STACOM power components to operate under fault current and dc-link voltage oscillations. The proposed control structure is designed based on adding appropriate oscillations to the conventional angle-controller output that is the control angle by which the VSC voltage vector leads/lags the line voltage vector. Since this control structure uses two angles for controlling the VSC output voltage, it is called dual angle control (DAC). PSCAD/EMTDC and experimental results verify the validity of the proposed control structure under unbalanced system conditions and faults. The experiments were conducted on a transient network analyzer, a unique hardware-based flexible ac transmission system simulator which was designed to study system faults and transients for a 2 × 100 MVA STATCOM field installation. [ABSTRACT FROM AUTHOR]

Hydro‐Québec's electrical transmission system is an extensive, international grid located in Québec, Canada with extensions into the northeastern United States of America. For large power systems such as this, one of the major issues is to maintain the steady‐state performance of the network. From this point of view, flexible AC transmission system (FACTS) devices could be effective tools to improve power system security by reducing the power flow on overloaded lines, which in turn would result in an increased loadability of the power system, reduced transmission line losses, improved stability and security and, ultimately, a more energy‐efficient transmission system. Therefore in this study, the authors will present the effects of different types of FACTS devices on the performance of Hydro‐Québec's power system. The optimal locations and rating of these FACTS controllers will be determined with a view to improving network security using an optimisation algorithm based on a genetic algorithm. The effects of six different FACTS devices including static VAR compensator (SVC), thyristor‐controlled series capacitor (TCSC), thyristor‐controlled voltage regulator (TCVR), thyristor‐controlled phase‐shifting transformer (TCPST), unified power flow controller (UPFC) and static synchronous compensator (STATCOM) with energy storage are compared. Using the presented results, the effects of different types of FACTS devices on the Hydro‐Québec network will be analysed and compared with those of a STATCOM equipped with energy storage from the viewpoints of static loadability and losses. [ABSTRACT FROM AUTHOR]

This study presents a secondary voltage control based on an optimisation algorithm to locate the control buses and regulate the voltage. Control buses are the buses where compensators will be installed on these buses to regulate voltage and avoid voltage violations. Firstly, partitioning algorithm using fuzzy C‐means has been implemented on the power network. Partitioning techniques split the power system into regions to avoid the propagation of disturbances between regions by using local controllers. Then, a number of buses are labelled as control buses displaying the critical point for voltage control in each region. The control algorithm is a decentralised controller which tries to eliminate voltage violations in power system resulting from load variations and disturbances. The decentralised controllers are implemented using flexible AC transmission system (FACTS) devices such as static synchronous compensator (STATCOM). The methodology is applied to the IEEE 118‐bus network. The results show the performance and ability of the partitioning algorithm and bus control selection to regulate the voltage and avoid propagation of disturbances between regions. [ABSTRACT FROM AUTHOR]

A robust coordination approach for the controller design of multiple high-voltage direct-current (HVDC) and flexible ac transmission systems (FACTS) wide-area controls (WACs) is presented in this paper and has the aim of stabilizing multiple interarea oscillation modes in large-scale power systems. The suitable wide-area control signals, which are given to HVDC and FACTS wide-area controllers, respectively, are chosen from a large number of candidate items. Then, a sequential robust design approach is planned for the wide-area controller coordination of HVDC and FACTS devices. This approach is based on the robust control theory and is formulated as a standard problem of multiobjective mixed H2/H\infty output-feedback control with regional pole placement constraints. The linear matrix inequality (LMI) theory is applied to solve such a robust control problem. A case study on the 16-machine 5-area system, which is modified with one HVDC interconnected transmission, one shunt-FACTS device (SVC), and one series-FACTS device (TCSC), is performed to validate the robust performance in terms of multiple oscillations damping under various operating conditions. [ABSTRACT FROM AUTHOR]

This paper presents an optimal allocation method for flexible ac transmission system (FACTS) devices for market-based power systems considering congestion relief and voltage stability. The purpose of the FACTS devices installation is to provide benefit for all entities accomplished by both minimizing annual device investment cost and maximizing annual benefit defined as difference between expected security cost (ESC) with and without FACTS devices installation. Different from previous approaches, the proposed method accurately evaluates the annual cost and benefits obtainable by FACTS devices installation by formulating a large-scale optimization problem that contains power flow analyses for a large number of system states representing annual power system operations. In addition, dynamic state transitions caused by specified contingencies are also simulated in the optimization problem to evaluate the effect of FACTS control actions as well as the other coordinated controls. The expected cost consists of operating cost under normal and contingency states along with their related probabilities to occur. Maximizing social welfare is the objective for normal state while minimizing compensations for generations re-scheduling and load shedding as well as maximizing social welfare are the objectives in case of contingency. Although installation cost of FACTS devices is required, they are useful as cost free means, which can reduce effectively the annual costs for generations re-scheduling and load shedding. [ABSTRACT FROM PUBLISHER]