Overcurrent Relay Coordination Problem Research Articles

Optimal coordination of directional overcurrent relays in complex networks using the Elite marine predators algorithm

The integration of renewable energy sources in the distribution network (DN) has had a significant influence by reducing power loss and enhancing network dependability. Aside from that, the protection system has met coordination issues as a result of bidirectional power flow and variations in fault levels. Therefore, an optimal coordination strategy is required to deal with relays coordination problem. The coordination problem of the directional overcurrent relays (DOCRs) is a restricted optimization issue that involves determining appropriate time dial settings (TDS) and plug setting (PS) to reduce relays operating time. Currently, a various nontraditional optimization strategies have been presented to overcome this challenge. In this paper, a modified version of the marine predators algorithm (MPA) referred to as Elite marine predator (EMPA) is developed for the optimal coordination of DOCRs. Therefore, the EMPA method is used to find out the optimal settings for the DOCRs problem. The suggested algorithm's performance is evaluated using standard test systems, including 3-bus, 8-bus, 9-bus, and 15-bus. The findings are compared with the traditional MPA and with other recent optimization methods presented in the literature to prove the efficiency and superiority of the proposed EMPA in reducing relay operation time for optimal DOCRs coordination.

Application of Time-Voltage Characteristics in Overcurrent Scheme to Reduce Arc-Flash Incident Energy for Safety and Reliability of Microgrid Protection

The interconnection between diverse Distribution Generations (DGs) that utilize various technologies and complex structure of networks are the most characteristic of modern Distribution Networks (DN). The wide adoption of DGs considerably affects the power flow dynamics in the DN and consequently the fault characteristics. The excessive level of fault currents can pose risks of heat (high temperature) and pressure in accordance to Arc Flash (AF) incident energy in microgrids. This research studies the relationship between AF severity and the solving of coordination problem of Overcurrent Relays (OCRs) in DN, and introduces a novel equation that considers the AF qualities in solving the coordination problem for OCRs. In this study, a novel optimization problem, the AF severity with the optimal coordination of OCRs in DN is presented and the Water Cycle Optimization Method (WCOM) is employed to find the best combination of the OCR’s settings in the DN while considering the AF induced energy. The proposed optimization approach and the novel equation are evaluated with an IEC microgrid and compared with the conventional protection method and Particle Swarm Optimization (PSO) used in optimizing the coordination of OCR in the DN. The optimal settings of the OCR scheme are achieved and examined on the modified IEC microgrid benchmark system. In order to verify the result, an industrial simulation package (ETAP) and OCR (GE Multiin, model-750/760) was used in this work.

Development and application of evaporation rate water cycle algorithm for optimal coordination of directional overcurrent relays

An optimization algorithm called modified evaporation rate water cycle algorithm (MERWCA) is proposed in this paper to find the optimal solutions for the coordination problem of directional overcurrent relays (DOCRs). The proposed MERWCA improves the performance of a conventional evaporation rate water cycle algorithm (ERWCA) by enhancing the balance between exploitation (search locally) and exploration (search globally) phases to find the best optimum solution. MERWCA includes the Opposition Based Learning (OBL) and Levy Flight (LF) component to address the shortcomings that the original ERWCA may exhibit, to avoid falling on the local optimal and improve the convergence rate. The proposed MERWCA is verified on the CEC’2017 test suite and its performance are compared with those of ten common metaheuristic algorithms (MAs). Both MERWCA and ERWCA are evaluated in the case of non-conventional and conventional relay curves. The feasibility of MERWCA technique is assessed using the conventional IEEE 39-bus meshed distribution test system. The results prove the viability of the MERWCA in solving DOCRs coordination problems in both cases (conventional and non-conventional characteristic relay curve) without any miscoordination between DOCRs pair. Moreover, the reduction ratio in minimizing the total operating using MERWCA reaches 46% with respect to the ERWCA and about 66% using the non-conventional relay characteristic. Finally, the MERWCA is assessed using benchmark DIgSILENT PowerFactory.

A Robust Adaptive Overcurrent Relay Coordination Scheme for Wind-Farm-Integrated Power Systems Based on Forecasting the Wind Dynamics for Smart Energy Systems

Conventional protection schemes in the distribution system are liable to suffer from high penetration of renewable energy source-based distributed generation (RES-DG). The characteristics of RES-DG, such as wind turbine generators (WTGs), are stochastic due to the intermittent behavior of wind dynamics (WD). It can fluctuate the fault current level, which in turn creates the overcurrent relay coordination (ORC) problem. In this paper, the effects of WD such as wind speed and direction on the short-circuit current contribution from a WTG is investigated, and a robust adaptive overcurrent relay coordination scheme is proposed by forecasting the WD. The seasonal autoregression integrated moving average (SARIMA) and artificial neuro-fuzzy inference system (ANFIS) are implemented for forecasting periodic and nonperiodic WD, respectively, and the fault current level is calculated in advance. Furthermore, the ORC problem is optimized using hybrid Harris hawks optimization and linear programming (HHO–LP) to minimize the operating times of relays. The proposed algorithm is tested on the modified IEEE-8 bus system with wind farms, and the overcurrent relay (OCR) miscoordination caused by WD is eliminated. To further prove the effectiveness of the algorithm, it is also tested in a typical wind-farm-integrated substation. Compared to conventional protection schemes, the results of the proposed scheme were found to be promising in fault isolation with a remarkable reduction in the total operation time of relays and zero miscoordination.

Optimal Protection Coordination of Nonstandard Overcurrent Relays Using Hybrid QCQP Method

The optimal protection coordination (OPC) problem of directional overcurrent relays (OcR) in power system networks is a complex, highly constrained nonconvex optimization problem because of the nonlinear inverse nature of the OcR characteristics. Finding the best OcR settings by solving OPC is a challenging task because of its nonconvex nature. Although various heuristic, hybrid heuristic, and traditional optimization-based solution methods are suggested in the literature, such methods are just far enough to provide better optimal solutions to the OPC problem. Besides, the standard inverse characteristics of the OcRs with fixed characteristic coefficients limit the OPC problem from finding the best settings. As digital relaying technology has the feasibility to embed more relay settings, nonstandard relay characteristics can be developed to achieve minimum relay operating times. To find the best OcR operating times, a nonstandard characteristic based OPC problem is formulated in this work by parameterizing the OcR characteristic coefficients along with the OcR settings. By setting two variables of the proposed OPC using particle swarm optimization (PSO), the rest of OPC is formulated as a quadratic programming problem with quadratic constraints (QCQP). The proposed method is developed in MATLAB programming platform, and results are found to be satisfactory.

Implementation of Hybrid ABC-PSO Algorithm for Directional Overcurrent Relays Coordination Problem

In modern power system, protective relays are playing a vital role for protection of the whole system. The efficiency and reliability of whole protection system depends upon the combined and coordinated operation of protective devices such as relays, circuit breakers etc. Moreover, both types of relays viz., primary and backup relays have been used for smooth and reliable operation of the power system from years. A primary directional over current relay (DOCR) is setup for the fast response of any faulty condition. If it fails, then backup relay perform the same task after some time gap. Three different setting such as plug-setting multiplier (PSM), pickup current settings and time multiplier setting (TMS) are required of performing the operation. In this paper, three very popular swarm based meta-heuristic such as particle swarm optimization (PSO), artificial bee colony (ABC) and a recent hybridization of both, i.e., hybrid ABC-PSO have been implemented for the calculation of optimal coordination problem. This coordination problem is treated for continuous settings optimization for TMS and pickup current. An IEEE 8 bus system without grid has been opted for validation of the results. It is evident from the study that the hybrid ABC-PSO based proves to generate optimal solution providing better convergence rate as compared to individual PSO and ABC algorithm.

The Comparison of Lately Proposed Harris Hawks Optimization and Jaya Optimization in Solving Directional Overcurrent Relays Coordination Problem

In this paper, a lately proposed Harris Hawks Optimizer (HHO) is used to solve the directional overcurrent relays (DOCRs) coordination problem. To the best of the authors’ knowledge, this is the first time HHO is being used in the DOCRs coordination problem. The main inspiration of HHO is the cooperative behavior and chasing style of Harris’ hawks from different directions, based on the dynamic nature of scenarios and escaping patterns of the prey. To test its performances in solving the DOCRs coordination problem, it is adopted in 3-bus, 4-bus, 8-bus, and 9-bus systems, which are formulated by three kinds of optimization models as linear programming (LP), nonlinear programming (NLP), and mixed integer nonlinear programming (MINLP), according to the nature of the design variables. Meanwhile, another lately proposed optimization algorithm named Jaya is also adopted to solve the same problem, and the results are compared with HHO in aspects of objective function value, convergence rate, robustness, and computation efficiency. The comparisons show that the robustness and consistency of HHO is relatively better than Jaya, while Jaya provides faster convergence rate with less CPU time and occasionally more competitive objective function value than HHO.

Optimal Coordination of Standard and Non-Standard Direction Overcurrent Relays Using an Improved Moth-Flame Optimization

In this paper, an efficient optimization technique, called improved moth-flame optimization (IMFO) is proposed to improve the performance of conventional Moth-flame optimization (MFO). Then, both of MFO and IMFO are applied to solve the coordination problem of standard and non-standard directional overcurrent relays (DOCRs). In the proposed IMFO, the leadership hierarchy of grey wolf optimizer is used to improve the performance of conventional MFO with the aim of finding the best optimum solution. The major goal for optimal coordination of DOCRs is to minimize the total operation time for all primary relays as well as satisfy the selectivity criteria between relay pairs without any violation in the operating constraints. The performance and feasibility of proposed IMFO are investigated using three different networks (8-bus network, 9-bus network, and 15-bus). The proposed IMFO is compared with conventional MFO and other well-known optimization techniques. The results show the effectiveness of the proposed IMFO in solving both standard and non-standard DOCRs coordination problems without any violation between primary and backup relays. In addition, the results show the power of proposed IMFO in finding the best optimal relay settings and minimizing the total operating time of relays which its reduction ratio reaches more than 28% with respect to the conventional MFO. Furthermore, the reduction in the total operating time of primary relays reaches more than 50 % with the usage of the non-standard relay curve.

Development and application of an efficient optimizer for optimal coordination of directional overcurrent relays

This paper proposes an enhanced version of grey wolf optimizer (EGWO) to solve the coordination problem of directional overcurrent relays (DOCRs). The EGWO is proposed to improve the convergence characteristics and computation time of the conventional grey wolf optimizer (GWO) by selecting a suitable balance between exploration and exploitation phases. This balance is achieved by exponential decreasing of the control parameter during the iterative process. The EGWO is explored in all search space during predetermined iterations, and then it fast converges to the best optimal solution by local exploitation around the optimal solutions. The proposed optimization technique is applied to solve the coordination problem of DOCRs. The main objective of optimal coordination of DOCRs is to minimize total operating time of all primary relays with sustaining the selectivity between relay pairs. The feasibility and performance of the proposed technique for solving the coordination problem of DOCRs are investigated using four different systems, compared with several well-known techniques. The obtained results prove the effectiveness and superiority of the proposed technique compared with these techniques. The proposed technique is able to find the optimal relay settings and minimize the total operating time of relays (with a reduction ratio about 19.3995% relative to the conventional GWO) without any miscoordination. In addition, DIgSILENT PowerFactory is used to validate the proposed technique.

Hybrid mixed‐integer non‐linear programming approach for directional over‐current relay coordination

This article proposes the optimal coordination problem of protective relays within a hybrid optimisation framework which is presented based on integer coded genetic algorithm (ICGA) and non-linear programming (NLP). The optimal coordination problem of directional overcurrent relays (DOCRs) is implemented while aimed at finding the optimal plug setting multiplier (PSM) and time dial setting (TDS). In this respect, PSM is a function of the current transformer (CT) size and the tap of the relay which is discrete in nature. TDS is a function of the operating time of the relay for different short-circuit currents at different locations of the system. Here, the variables of the problem are decomposed into continuous and discrete variables. The first stage of the problem uses the ICGA to determine the size of CTs considering the permitted tap of relays while the second stage utilises the NLP method to evaluate the feasibility and optimality. The presented framework is then simulated on an 8-bus test system. The obtained results verify the effectiveness and the applicability of the optimisation technique to find the optimal settings of DOCRs.

A New Mixed Integer Linear Programming Formulation for Protection Relay Coordination Using Disjunctive Inequalities

Numerical optimization-based solution to directional overcurrent relay (DOCR) coordination problem has been a widely addressed research problem in the recent past. Many linear (LP), nonlinear (NLP), mixed integer nonlinear (MINLP), mixed integer linear (MILP), and quadratically constrained quadratic programming (QCQP)-based formulations have been presented in the past literature. This paper proposes a new MILP-based formulation using disjunctive inequalities. The nonlinear DOCR protection coordination model is formulated as MILP by linearizing the bilinear terms existing in the original formulation. One of the variables in each bilinear term is discretized over its interval into a fixed number of steps. After assigning binary variables to each discrete interval, the resulting bilinear terms with binary variables are written in terms of disjunctive inequalities. The results have shown that the proposed MILP formulation fetch better optimal solutions compared with past MILP and MINLP formulations. The MILP problem is programmed in GAMS package with CPLEX solver and tested on standard 3 bus, 9 bus, 15 bus, and 30 bus systems and results are found to be satisfactory.

Hybrid Whale Optimization Algorithm and Grey Wolf Optimizer Algorithm for Optimal Coordination of Direction Overcurrent Relays

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.

A Novel Convexified Linear Program for Coordination of Directional Overcurrent Relays

A novel convexified linear program for optimal directional overcurrent relay (DOCR) coordination problem (CP) is proposed in this letter. The DOCR CP is a highly constrained nonlinear nonconvex problem which was solved using various traditional and heuristic optimization techniques in the past. In this letter, the CP is formulated as a linear programming problem without fixing the current pickup settings of DOCRs. The bilinear terms in the proposed formulation are written in the form of linear inequalities using McCormick envelopes. A sequential tightening algorithm is used to update the boundary limits of each parameter based on the solution obtained in each iteration, thus tightening the convex hulls and leading to solutions near to global optimum. The performance of the proposed method is applied to various test systems among which the results of three bus test system are presented.

MILP approach for optimal coordination of directional overcurrent relays in interconnected power systems

The coordination problem of directional overcurrent relays (DOCRs) is a non-linear and non-convex optimization one. Until now, several methods based on the heuristics and non-linear programming (NLP) approaches have been proposed for solving the problem. Drawback of these methods is that they are likely to be trapped in local minima. In order to overcome the drawback, in this paper, the problem is formulated as a mixed integer linear programming (MILP) while pickup current setting (Iset) and time multiplier setting (TMS) of relays are considered as optimization variables. This formulation is easier to be solved by branch and bound (B&B) approach, because at each branch there is a linear and convex sub-problem. Furthermore, for the first time, the proposed method is guaranteed to converge to global optimal settings. The proposed method is evaluated using a 3-bus, an 8-bus, the IEEE 14-bus and the modified IEEE 30-bus test systems. The results are compared with some previous heuristics and NLP approaches. Based on the obtained results, it can be seen that, better optimal settings for DOCRs are obtained by using the proposed method in comparison with previous methods.

Optimal Overcurrent Relays Coordination using an Improved Grey Wolf Optimizer

Recently, nature inspired algorithms (NIA) have been implemented to various fields of optimization problems. In this paper, the implementation of NIA is reported to solve the overcurrent relay coordination problem. The purpose is to find the optimal value of the Time Multiplier Setting (TMS) and Plug Setting (PS) in order to minimize the primary relays’ operating time at the near end fault. The optimization is performed using the Improved Grey Wolf Optimization (IGWO) algorithm. Some modifications to the original GWO have been made to improve the candidate’s exploration ability. Comprehensive simulation studies have been performed to demonstrate the reliability and efficiency of the proposed modification technique compared to the conventional GWO and some well-known algorithms. The generated results have confirmed the proposed IGWO is able to optimize the objective function of the overcurrent relay coordination problem.

Enhanced differential evolution algorithm for coordination of directional overcurrent relays

This paper presents an enhanced differential evolution algorithm (DE) for solving the directional overcurrent relay (DOCR) coordination problem. Comparisons among different versions of DE for coordination of DOCRs in larger and interconnected power systems are presented. The evaluation criteria consist of fitness value, number of violation and standard deviation. The outstanding DE algorithm has been enhanced in four aspects: dial reduction scheme, elitism and mediocrity scheme, mutation index renew scheme, and population reduction scheme. The enhanced-DE (eDE) shown best result in terms of execution time, result quality, robustness and convergence ability compared to the others analyzed in this research. The IEEE 14 and 57 bus systems are used to validate the proposed algorithm. A significant comparison result between eDE and DE on the IEEE 57 bus network are: execution time in seconds 364 vs. 2040, fitness value 1.933 vs. 7.91, and standard deviation of fitness value 0.018 vs. 5.52. Results are averaged values in 50 runs.

Optimal Application of Fault Current Limiters for Assuring Overcurrent Relays Coordination with Distributed Generations

This paper addresses the problem of overcurrent relays (OCRs) coordination in presence of DGs. OCRs are optimally set to work in a coordinated manner to isolate faults with minimal impacts on customers. Penetration of DGs into the power system changes the fault current levels seen by the OCRs. This can deteriorate the coordinated operation of OCRs. Operation time difference between backup and main relays can be below the standard limit or even the backup OCR can incorrectly work before the main OCR. Though resetting of OCRs is tedious especially in large systems, it cannot alone restore the original coordinated operation in the presence of DGs. The paper investigates the optimal utilization of fault current limiters (FCLs) to maintain the directional OCR-coordinated operation without any need to OCRs resetting irrespective of DGs status. It is required to maintain the OCRs coordination at minimum cost of prospective FCLs. Hence, the FCL location and sizing problem are formulated as a constrained multi-objective optimization problem. Multi-objective particle swarm optimization is adopted for solving the optimization problem to determine the optimal locations and sizes of FCLs. The proposed algorithm is applied to meshed and radial power systems at different DGs arrangements using different types of FCLs. Moreover, the OCR coordination problem is studied when the system includes both directional and non-directional OCRs. Comparative analysis of results is provided.

Modified Swarm Firefly Algorithm for Optimal Settings of Directional Overcurrent Relays

This paper presents a new approach known as Modified Swarm Firefly Algorithm (MSFA) technique in solving Directional Overcurrent Relays (DOCRs) coordination problem by minimizing the operating time of primary relays at near-end fault. DOCRs coordination requires the optimal values of Time Multiplier Setting (TMS) whereas the pickup current (Ip) values are based on load and data fault. The proposed technique is tested on IEEE 14-bus system and is compared with Particle Swarm Optimization (PSO). The simulation results revealed that the MSFA technique outperformed PSO in terms of minimizing fitness values.

A comparative study of metaheuristic optimization approaches for directional overcurrent relays coordination

In this paper, a comparative study of different meta-heuristic optimization approaches, which had been proposed in the literature for directional overcurrent relay coordination (DOCRs), is presented. Towards this goal, five most effective meta-heuristic optimization approaches such as genetic algorithm (GA), particle swarm optimization (PSO), differential evolution (DE), harmony search (HS) and seeker optimization algorithm (SOA) have been considered. The performances of these optmization methods have been investigated on several power system networks of different sizes. The comparative performances of these methods have been studied by executing each method 100 times with the same initial conditions and based on the obtained results, the best meta-heuristic optimization method for solving the coordination problem of directional overcurrent relays is identified.

Optimal allocation of fault current limiters for sustaining overcurrent relays coordination in a power system with distributed generation

This paper addresses the problem of overcurrent relays (OCRs) coordination in the presence of DGs. OCRs are optimally set to work in a coordinated manner to isolate faults with minimal impacts on customers. The penetration of DGs into the power system changes the fault current levels seen by the OCRs. This can deteriorate the coordinated operation of OCRs. Operation time difference between backup and main relays can be below the standard limit or even the backup OCR can incorrectly work before the main OCR. Though resetting of OCRs is tedious especially in large systems, it cannot alone restore the original coordinated operation in the presence of DGs. The paper investigates the optimal utilization of fault current limiters (FCLs) to maintain the directional OCRs coordinated operation without any need to OCRs resetting irrespective of DGs status. It is required to maintain the OCRs coordination at minimum cost of prospective FCLs. Hence, the FCLs location and sizing problem is formulated as a constrained multi-objective optimization problem. Multi-objective particle swarm optimization is adopted for solving the optimization problem to determine the optimal locations and sizes of FCLs. The proposed algorithm is applied to meshed and radial power systems at different DGs arrangements using different types of FCLs. Moreover, the OCRs coordination problem is studied when the system includes both directional and non-directional OCRs. Comparative analysis of results is provided.