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Backward/forward load flow algorithm is commonly used in the power system, particularly in radial distribution networks. However, the rapid development in the power electronics technologies makes power systems more flexible with the integration of Renewable Energy Resources (RESs) and compensation devices. Consequently, this paper presents simple models for wind turbine generators based on Squirrel Cage Induction Generator (SCIG) and Distribution Static Synchronous Compensator (DSTATCOM) into a backward/forward load flow algorithm. In the wind generator model, the mechanical powers are collected from the manufactures data where the electrical power is calculated through the SCIG equivalent circuit and injected as negative loads at the connected buses. The second model in this paper is the DSTATCOM devices which are utilized to recover the SCIG reactive power. In the proposed model, the connected DSTATCOM bus is converted to a voltage-controlled bus (PV-bus type) with zero active power. Moreover, the reactive power of the DSTATCOM is updated during the iterative process until the load flow convergence. The simplified models for both wind generators and DSTATCOM are validated based on standard IEEE 33-bus and 85-bus radial distribution systems. The obtained results show the feasibility and effectiveness of the proposed models. [ABSTRACT FROM AUTHOR]

This paper presents a modeling for D-STATCOM device into Monte Carlo probabilistic load flow algorithm. The model is used to improve the predictability and voltage profile of distribution networks. In this model, the D-STATCOM's bus is represented as a special generator bus which injects reactive power only. The injected reactive power of D-STATCOM is updated during the iterative process to maintain the voltage magnitude at the specified value. The model can be easily implemented in the original PLF code without deeply modifications. The probabilistic load flow (PLF) with D-STATCOM model is validated using various standard IEEE tests systems; 33-bus, and 69-bus systems. The PLF algorithm with DSTATCOM model has been evaluated based on MATLAB package. However, the obtained results prove the effectiveness of D-STATCOM implementation in the test systems regarding to predictability and voltage profile issues. Moreover, the standard deviation of the systems is decreased. [ABSTRACT FROM AUTHOR]

In this article, the optimal allocation of compensation devices in power systems is determined using Improved Moth-flame Optimization (IMFO) algorithm. The main objective of this study is to maximize power system loadability, reduce total power system losses and enhance the voltage profile through finding the optimal locations and sizes of Static VAR Compensator (SVC) and Thyristor Controlled Compensator (TCSC). The methodology of this article is based on Continuation Power Flow (CPF) which is merged with IMFO in Optimum Power Flow (OPF) problem restricted by equality and inequality constraints. The proposed algorithm is implemented to regulate the required control variables. Both of single and multi-objective functions are applied on 57-IEEE bus test system to prove the performance of the proposed algorithm. The acquired simulation results by IMFO are compared with Moth Flame Optimization technique (MFO) and Multi Verse Optimizer (MVO) to emphasize the robustness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

This paper proposes a novel hybrid (MFO-SCA) method based on Moth Flame Optimization (MFO) algorithm and Sine Cosine Algorithm (SCA). MFO is utilized for the exploitation phase while SCA is used for the exploration phase. In addition, the hybrid MFO-SCA method is used with combined power loss sensitivity (CPLS) to determine the optimal allocation of single and multiple of distributed generations (DGs) and capacitors in distribution system. In this paper, the total active power loss is used as a single objective function for incorporating DGs and capacitors in RDS. Also, this paper studies the system performance when integrating DGs or capacitors alone and DGs with capacitors simultaneously in RDS. The proposed method is validated using the standard IEEE 69-bus and IEEE 33-bus radial distribution system (RDS). From comparative study, the novel hybrid MFO-SCA proved its effectiveness in obtaining the best global optimum results of the objective function compared with other recent optimization techniques, especially SCA and MFO algorithms. [ABSTRACT FROM AUTHOR]

The voltage stability analysis can be carried out using different continuation techniques. The continuation power flow that evaluates all power-flow solutions at different loading levels, is typically considered the most standard one. This approach is mainly based on two stages called predictor and corrector. The standard Newton–Raphson method is usually used at the corrector stage. In this paper, several corrector techniques based on efficient Newton-like methods are proposed in order to speed up the solution of continuation power flow. Consequently, two high order Newton-like methods as well as a fast corrector technique based on the Dishonest NR method have been proposed. A comprehensive study is addressed in order to check the suitability of the proposed corrector techniques compared with the standard Newton–Raphson (NR). Several small, medium, large and very large-scale test systems are used to achieve the validation. The obtained results prove the effectiveness and superiority of proposed techniques compared with the standard NR which conventionally used in corrector stage of the continuation power flow analysis in term of computational time. [ABSTRACT FROM AUTHOR]

This paper deals with the simultaneous tuning of proportional integral controller of static synchronous compensator (STATCOM) associated with lead-lag controller (LL) in order to improve the stability performance of combined wind farm (CWF). This type of farms has been developed to summarize the main benefits of Squirrel-Cage Induction Generator (SCIG) and doubly fed induction generators (DFIG). The performance of CWF with the tuned STATCOM is studied during line-to-line and three-phase faults. Multi-objective Lightning Attachment Procedure Optimization Algorithm (LAPO) is used as an intelligent optimization technique to determine the control parameters which can achieve the specified objective functions; minimizing the error signal and maximizing the output signal. The multi-objective LAPO is used to obtain the optimized values of AC voltage regulator, DC voltage regulator, current regulator, gains and time constant of LL. The ability of STATCOM tuned by multi-objective LAPO is examined by studying the performance of three wind farms. The first one is CWF and two other wind farms; one of them is based only on SCIG (SCIG-WF) and the other based only on DFIG (DFIG-WF) when they associated with the tuned STATCOM LAPO during grid fault. The results show that CWF associated with the tuned STATCOM LAPO has the best performance during grid faults compared with the other wind farms. [ABSTRACT FROM AUTHOR]

Recently, integration of distributed generations (DGs) and shunt capacitors in radial distribution network are becoming popular to withstand the rapidly increasing in electricity demands. In this article, a hybrid method is proposed to obtain the best locations and sizes of capacitors and DGs in radial distribution network. This hybrid method is based on chaotic whale optimization algorithm (CWOA) and loss sensitivity factor (LSF). The proposed method is tested on IEEE 69-bus system to enhance the buses voltages, increase the distribution system capacity, and decrease the total power loss. The obtained results prove that the proposed method based on CWOA and LSF can be highly effective in determining the locations and sizes of capacitors and DGs in RDS compared with other optimization techniques. [ABSTRACT FROM AUTHOR]

In this article, a new hybrid metaheuristic optimization algorithm is proposed to solve the coordination problem of directional overcurrent relays (DOCRs). The proposed algorithm is constructed using hybrid whale optimization algorithm and gray wolf optimizer (HWGO) that enhance the performance and reliability of the traditional whale optimization algorithm (WOA). The proposed method enhances the exploitative phase of the WOA using a leadership hierarchy of the gray wolf optimizer (GWO) to find the best optimum solution. The coordination problem of DOCRs is subject to numerous constraints. The goal function for optimal coordination of DOCRs aims to minimize total operation time for all primary relay without violation in constraints to maintain reliability and security of the electric power system. The effectiveness of the proposed algorithm has been investigated on four different interconnected networks. The results using HWGO algorithm are compared with the original WOA, GWO, and earlier reported results of other optimization techniques. The results prove the viability of the proposed algorithm to solve the DOCR coordination problem and the ability of the proposed algorithm to overcomes the drawbacks and cover the weakness of the conventional WOA. [ABSTRACT FROM AUTHOR]

Although the wind farms based on squirrel cage induction generators (SCIG) is cheaper than the wind farms based on doubly fed induction generators (DFIG), it is always in desperate need for reactive power compensation. Nevertheless, the wind farms based on DFIG are expensive compared with the SCIG wind farm, it features by its ability to control the active power independent of reactive power. However, combined wind farm (CWF) has been developed to collect the benefits of SCIG and DFIG wind turbines in the same wind farm. In this article, artificial neural network (ANN) is used to evaluate gain parameters of static synchronous compensator (STATCOM) in order to improve the stability performance of CWF. The impact of tuned STATCOM on the performance of CWF during gust wind speed and during three-phase fault is comprehensively investigated. The performance of CWF with STATCOM tuned by ANN is compared with its performance when the STATCOM tuned by the multiobjective genetic algorithm (MOGA) and whale optimization algorithm (WOA). The results show that the performance of CWF can be enhanced using STATCOM tuned by ANN more than MOGA and WOA. [ABSTRACT FROM AUTHOR]

Generalized Unified Power Flow Controller (GUPFC) is one of the newest Flexible AC transmission system (FACTS) devices based on voltage source converters. This paper presents a developed model of GUPFC based on power injection approach. The series converters of GUPFC is represented by injected complex loads as function of the specified powers flow, while the shunt converter is represented as a synchronous condenser that provides the reactive power compensation to control the bus voltage magnitude. The main advantage of the developed model is that the original structure and symmetry of the admittance and Jacobian matrices can still be kept avoiding the changes of the original Jacobian matrix. Consequently, the complexities of the load flow are reduced. This model includes simple strategies for handling the operating constraints of GUPFC, including the injected series and shunt voltages magnitude, currents of the series and shunt converters, and the real powers exchanged in the converters. The strategies are based on decreasing one or more values of specified values or by modifying the specified values as a function of the required constraint limits. The developed model and proposed strategies for handling violation of GUPFC operating constraints are tested on IEEE test systems such as 57-bus and 118-bus systems. [ABSTRACT FROM AUTHOR]

Abstract—This article shows a method to optimize the reliability of an electric power system by the introduction of distributed generation. The reliability index of the system is determined as the failure probability of the system. A hybrid method that uses a binary shuffled frog-leaping algorithm and probabilistic load flow is proposed to search a large number of combinations for location and size of biomass power plants and photovoltaic units. The combination with the best performance minimizes the reliability index (probability of failure) of the system. [ABSTRACT FROM PUBLISHER]