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Voltage instability in power systems arises due to the shortage of reactive power and may cause abnormally low bus voltages leading to a partial or complete blackout. In order to maintain the system voltages within a safe limit, voltage control techniques such as shunt capacitor banks, Static VAR Compensators (SVCs), load shedding, and transformer tap-changer blocking, are employed. In this paper, a novel receding-horizon Model Predictive Control (MPC)-based voltage controller is proposed, which, by optimally controlling generator reactive power and SVC output, maintains the voltage stability of a power system. For this, a sensitivity-based analysis is performed to design a state-space model of the power system. The frequency and voltage dependency of load and generation are considered in the system equations. The voltage control is done step-wise, and the optimal control action in each step is calculated by minimizing a cost function subject to a set of relevant constraints. Different Voltage Stability Indices (VSIs) are used as a measure of voltage stability and also used in the constraints for the optimization problem. The performance of the proposed controller is evaluated on IEEE 9-, 39- and 118-bus systems, considering different types of loads and contingencies. [ABSTRACT FROM AUTHOR]

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]

This paper presents new methodologies for modeling static VAr compensators (SVCs) in the power flow problem. The proposed formulations utilize sigmoid functions to model the control equations that describe the steady-state behavior of SVCs. The first methodology introduces reactive power injection as a new state variable, while the second methodology utilizes the thyristor firing angle. These steady-state SVC methodologies were applied to the power flow problem using the full Newton formulation, which incorporates the control equations into the system of nonlinear equations. One of the main contributions of these proposed methodologies is that they eliminate the need for alternating adjustments concerning the operational limits of the SVC during the iterative power flow process. The implementation of a power flow program was tested on both small-scale tutorial systems and the medium-scale IEEE Nordic system. The presented results validate and demonstrate the effectiveness of the proposed methodology. [ABSTRACT FROM AUTHOR]

This study presents a low-cost thyristor-controlled LC compensator scheme for the improvement of overall power quality in the distribution system. The parameters of the compensator have been designed and optimal triggering angles for thyristor switching have been obtained for reducing the unbalanced condition and harmonic injection at a high power factor. Compared to the traditional static VAr compensator schemes, the proposed technique can significantly reduce the harmonic injection into the system. The particle swarm optimization technique has been applied to compute the optimal triggering angles, and different aspects of the power quality factor have been assessed through rigorous simulations. Power quality assessment has been further validated through an experimental setup in the laboratory. Finally, a comparison of the proposed scheme with other similar schemes has been carried out to highlight its efficacy. [ABSTRACT FROM AUTHOR]

The power factor of industrial facilities is typically inductive. The case study in this paper was based on a typical Malaysian 11-kV on-grid industrial system with renewable energy sources and electric vehicle charging station connected. The integration of renewable energy sources reduces energy consumption from the grid; it consecutively reduces greenhouse gas emissions. However, the integration of renewable energy sources such as solar photovoltaic operating at unity power factor results in a reduction of the industry's power factor. According to the Malaysian Distribution Code, the power factor of a medium voltage industrial system should be more than 0.85 lagging. A long-term low power factor will reduce the related electrical equipment lifespan and increase the monthly electricity bills. A classic method to overcome this issue was by installing reactive power compensator devices, such as the synchronous condenser, static VAr compensator and static synchronous compensator. Studies had revealed that solar photovoltaic with appropriate control system design could perform short-term reactive power compensation. The control techniques used are either power factor control, active power control, reactive power control or any combination of them. However, neither the reactive power compensator devices nor the solar photovoltaic with a control system can regulate the industry's power factor to an intended value throughout its operation. Thus, this paper presents a simple, relatively cost-effective design of a master power factor controller that is capable of regulating the industry's power factor to an intended value throughout its operation with a single preset reference. In this research, an industry-grade system comprises an industrial load installed with a power factor-controlled capacitor bank, a power factor-controlled solar photovoltaic system, a bidirectional current-controlled electric vehicle charging system based on CHAdeMO 1.1 standard charging protocol and a master power factor controller was designed using the Matrix Laboratory/Simulink software. This paper has provided simulation results as proof that each of the designed equipment was functioning appropriately. The results also proved that the proposed master power factor controller was capable of regulating the power factor of the industrial system to above 0.85 lagging throughout its operation. [ABSTRACT FROM AUTHOR]

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. [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]

This paper introduces Simulink-based programs developed for dynamic analysis of electrical power systems. The program can be used for research studies or as a teaching tool. With the program, time-domain simulation, modal analysis, participation factor analysis and visualization, frequency response analysis, and design of conventional and intelligent controllers can be obtained. A special case of constant impedance load is also studied. IEEE 9-bus, IEEE 68-bus, Texas 2007-bus 282-machine, and the 25,000-bus northeastern US test systems are employed in this paper. The synchronous machines are assumed to be equipped with exciter, turbine, and stabilizer. Static var compensator is added using conventional and adaptive neuro-fuzzy controllers. Different types of disturbances are applied to the systems including generator-side and network-side disturbances. The program is free of algebraic loops that may increase the errors and slow down the simulation. All blocks and signals in the Simulink model are in vector form that can be used to simulate a power system of any size. [ABSTRACT FROM AUTHOR]

Among the existing power quality problems, the reactive power compensation plays a key role once it helps to maintain the system stability and increases the efficiency. Currently, there are many solutions for reactive power compensation, which unfortunately present a wide variety of problems as large inrush currents, non-continuous compensation and harmonics injection in the system. The application of devices like static VAr compensator, static synchronous compensator or unified power flow controller has demonstrated to be an effective solution for reactive power compensation. However, it is important to note that these options are rarely used in distribution systems by companies that prefer to assimilate the drawbacks of switched capacitor banks instead of investing in more expensive, sophisticated and complex solutions. Despite the large number of proposed devices in distribution systems, there is a lack of solutions with emphasis on cost reduction. Therefore, this paper presents a new topology for reactive power compensation and voltage control in distribution systems. The proposed topology has several interesting features as reduced switching losses, small capacitors and simple control scheme. In addition, the proposed solution uses already existing capacitor banks which makes possible its usage in distribution companies with minimum modifications. Experimental results have been obtained on a 6-kVA prototype to demonstrate the feasibility of the proposed solution. [ABSTRACT FROM AUTHOR]

Increasing in the scale and complexity of interconnected power systems was because of the growth of electricity demands, leading to multiple electromechanical oscillations despite having support of the power system stabilizer (PSS). Therefore, the dynamic performance of the existing networks should enhance. One type of flexible alternating current transmission system devices, namely the static var compensator (SVC), can be installed at the buses to maintain and/or control particular parameters of the electrical power system by exchanging capacitive and/or inductive current. However, the performance of SVC device highly depends upon its parameters, sizes, and suitable number and location in the power network. Hence, the optimal location for SVC has become a key issue; in this paper, we propose a novel approach for the suitable number and location for SVC by using critical energy analysis based on the Gramian matrices that the solution framework applied an algorithm based on the Lyapunov equations and the balanced realization technique. The optimal placement is determined by (1) analyzing the small-signal stability to seek number of feasible locations and (2) comparing these feasible locations by analyzing the transient stability through various simulation cases. The effectiveness of the proposed method is compared with the other optimal method and verified on the 39-bus New England system by the simulation results based on the power system simulation engineering (PSS/E) and MATLAB programs. The obtained result shows that the SVC is installed at the single or multi-location having the total maximum Gramian energy. [ABSTRACT FROM AUTHOR]

The main objective of the present paper is to introduce a new approach for measuring and calculation of fundamental power components in the case of various distorted waveforms including those containing harmonics. The parameters of active, reactive, apparent power and power factor, are measured and calculated by using Goertzel algorithm instead of fast Fourier transformation which is commonly used. The main advantage of utilizing Goertzel algorithm is to minimize computational load and trigonometric equations. The parameters measured in the new technique are applied to a fixed capacitor-thyristor controlled reactor based static VAr compensation system to achieve accurate power factor correction for the first time. This study is implemented both simulation and experimentally. [ABSTRACT FROM AUTHOR]

In this paper, an internal model control recurrent neural network method is used to control the switching of thyristor-controlled reactor in a static VAR compensator (SVC) system for regulating the voltage. The novel controller scheme contains several feedback loops instead of only a feed-forward loop as in the conventional recurrent neural network (RNN). In the proposed controller model, the RNN identifier creates a sample of the connected system and its output generates a part of inputs for the RNN controller which then sends the control signal to the SVC system. Three types of non-linear conditions are chosen to test the operational capability of the new control system to perform the voltage regulation satisfying the IEEE Std 519-1992. The test cases contain a three-phase fault power system, opening of one of the transmission lines in a double line transmission system and sudden changes in the load demand. Results show that the proposed control model is capable of regulating the voltage of the system in a desired range. [ABSTRACT FROM AUTHOR]