Coordination Problem Of Directional Overcurrent Relays Research Articles

A Novel Application of Fractional Order Derivative Moth Flame Optimization Algorithm for Solving the Problem of Optimal Coordination of Directional Overcurrent Relays

The proper coordination of directional overcurrent relays (DOCRs) is crucial in electrical power systems. The coordination of DOCRs in a multi-loop power system is expressed as an optimization problem. The aim of this study focuses on improving the protection system’s performance by minimizing the total operating time of DOCRs via effective coordination with main and backup DOCRs while keeping the coordination constraints within allowable limits. The coordination problem of DOCRs is solved by developing a new application strategy called Fractional Order Derivative Moth Flame Optimizer (FODMFO). This approach involves incorporating the ideas of fractional calculus (FC) into the mathematical model of the conventional moth flame algorithm to improve the characteristics of the optimizer. The FODMFO approach is then tested on the coordination problem of DOCRs in standard power systems, specifically the IEEE 3, 8, and 15 bus systems as well as in 11 benchmark functions including uni- and multimodal functions. The results obtained from the proposed method, as well as its comparison with other recently developed algorithms, demonstrate that the combination of FOD and MFO improves the overall efficiency of the optimizer by utilizing the individual strengths of these tools and identifying the globally optimal solution and minimize the total operating time of DOCRs up to an optimal value. The reliability, strength, and dependability of FODMFO are supported by a thorough statistics study using the box-plot, histograms, empirical cumulative distribution function demonstrations, and the minimal fitness evolution seen in each distinct simulation. Based on these data, it is evident that FODMFO outperforms other modern nature-inspired and conventional algorithms.

A Robust Protection Scheme for Multimicrogrids Using Fault Current Limiter

The operation of multimicrogrids (MMGs) can cause significant impact on power system network, especially changes in level and direction of fault current. The fault current level may exceed rating of existing directional overcurrent relays (DOCRs) that lead to sympathetic tripping or fail to trip DOCRs in the network. It is expensive and extremely challenging to upgrade or replace the existing DOCRs in the network. If not properly addressed, this issue may hinder the deployment of MMGs in to the network. Hence, this article proposes a robust protection scheme for DOCRs coordination in MMGs without replacing existing DOCRs in network. First, the proposed scheme calculates optimal settings of DOCRs in all stand-alone microgrids of MMG during islanded mode. Then, optimal values of fault current limiters are obtained using calculated optimal settings. The main advantage of proposed scheme is that it provides one set of DOCRs settings valid for all operating modes of MMG. In this work, the DOCRs coordination problem is formulated as nonlinear problem and solved using proposed hybrid approach symbiotic organisms search (SOS) and nonlinear programming (NLP). The initial solution is determined by SOS and final solution is obtained using NLP. Further, the proposed scheme is examined during gird connected and islanded modes in two different configurations (series and parallel) of MMG, which are not stated in previous literature. Finally, simulation results are validated using numerical relay and real time digital simulator, which are interfaced through voltage and current amplifier to execute hardware-in-loop test bed.

Optimal coordination of directional overcurrent relays using hybrid fractional computing with gravitational search strategy

The protection system has a vital role in subsystems of the power network including the generation, transmission and distribution system. This system combines several types of protection relays including directional over current relay, differential relay, distance relay, earth faults relay, inverse definite minimum time (IDMT) relay for the protection of line, generators bus bars, transformers, line to ground faults and feeder lines of the power system. In this research paper, the overall performance of the protection system is improved by reducing the overall operational time of directional over current relays (DOCRs) through the optimal coordination between the primary and backup over current protective relays while keeping the time multiplier setting (TMS), pickup tap setting (PTS) and coordination time of interval (CTI) within the allowable limits. A new optimization strategy, namely the FPSOGSA, is developed by integrating the concept of fractional calculus inside the mathematical model of canonical particle swarm optimization and combining with traditional gravitational search algorithm to enhance the optimizer characteristics and tested on coordination problem of DOCRs in standard power systems including the IEEE 3, 8 and 15 bus networks. The results, yielded by proposed algorithm and their comparison with other well-known recently established counterparts, reveal that the synergy of FC, PSO and GSA enhance the performance of the optimizer by combining the individual strengths of these tools and finding the best global solution. The consistency, stability and reliability of FPSOGSA is endorsed by comprehensive statistical analysis based on the empirical cumulative distribution function, histograms, boxplot illustrations, quantile–quantile plots, minimum fitness evolution in each independent simulation.

A two stage fault current limiter and directional overcurrent relay optimization for adaptive protection resetting using differential evolution multi-objective algorithm in presence of distributed generation

This paper presents a two stage optimization approach for solving the excessive network fault currents and resetting of overcurrent relays based on Adaptive Protection Scheme (APS) concept. The first stage consists of Fault Current Limiter (FCL) optimization to restore fault currents within Circuit Breaker (CB) thermal capacity whether caused by Distributed Generation (DG) or not. The second stage consists of Directional Overcurrent Relay (DOCR) coordination based on the adaptive protection concept to reset DOCR in order to function properly in presence of FCL and DG. This is of great importance since FCL may cause over limitation of fault current during minimum load operation which may degrade DOCR performance. The optimization process has been achieved by formulating both the FCL sizing and location problem and DOCR coordination problem using Differential Evolution Multi-Objective (DEMO) algorithm. The proposal has effectively re-coordinated the DOCRs contemplating the effects of FCLs and DGs which mitigated the faults surpassing CB thermal limit, DOCR miscoordination and degraded performance caused by FCL over limitation.

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.

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.

Preprocessing of distance and directional overcurrent relays coordination problem considering changes in network topology

Summary The number of constraints in coordination of distance and directional overcurrent relays (D&DOCRs) in power systems increases significantly by considering changes in network topology, especially in large power systems. By increasing the number of coordination constraints, the complexity of the D&DOCRs coordination problem is increased. Therefore, in this paper, a new method is proposed to reduce the number of coordination constraints in the D&DOCRs coordination problem. In the proposed method, redundant constraints are identified before solving the coordination problem. The proposed method is independent from D&DOCRs settings and operating characteristics of directional overcurrent relays. In order to evaluate the proposed method, two different test systems, namely, an 8-bus and the IEEE 14-bus test systems, are used. Based on the presented results, it can be seen that the proposed method is efficient, and by utilizing it, many redundant coordination constraints are identified and removed, helping to obtain effective solutions for the optimal settings with less computational effort. Copyright © 2015 John Wiley & Sons, Ltd.

A New Algorithm to Avoid the Infeasibility of Linear Programming Techniques Used to Solve the Over-current Relays Coordination Problem

This article analyzes the drawbacks of linear programming methods to solve the directional over-current relay coordination problem. The solution infeasibility of these methods is due to selectivity constraints, which reduce the upper bound of the time multiplier setting of some relays. This infeasibility can be avoided by making the upper bound of the time multiplier setting insensible to selectivity constraints. With the proposed algorithm based on this idea, the constraints causing infeasibility are identified in order to change their position in relation to possible solution areas. This change is achieved by increasing the relay pickup currents. The proposed algorithm is tested and evaluated on the IEEE 14-bus and 30-bus networks. The results show that the previously infeasible solution of linear programming becomes feasible with high efficiency.

Resolving the impact of distributed renewable generation on directional overcurrent relay coordination: a case study

Two approaches are proposed to solve the directional overcurrent relay coordination problem associated with the installation of distributed renewable generation (DRG) in interconnected power delivery systems (IPDS), depending on the existing system protection capability (adaptive or non-adaptive). For adaptive protection systems, the first proposed approach introduces a procedure to select the optimal minimum number of relays, their locations and new settings. This procedure is restricted by the available relay setting groups. For non-adaptive protection systems, the second proposed approach implements a practice to obtain optimal minimum fault current limiter values (FCL) to limit DRG fault currents and restore relay coordination status without altering the original relay settings. An integration of the proposed two approaches is evaluated for IPDSs possessing both protection systems. Three scenarios are assessed for different numbers of DRGs, and DRG and fault locations using an optimisation model implemented in GAMS software and a developed MatLab code. The obtained results are reported and discussed.

Restoration of Directional Overcurrent Relay Coordination in Distributed Generation Systems Utilizing Fault Current Limiter

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A new approach is proposed to solve the directional overcurrent relay coordination problem, which arises from installing distributed generation (DG) in looped power delivery systems (PDS). This approach involves the implementation of a fault current limiter (FCL) to locally limit the DG fault current, and thus restore the original relay coordination. The proposed restoration approach is carried out without altering the original relay settings or disconnecting DGs from PDSs during fault. Therefore, it is applicable to both the current practice of disconnecting DGs from PDSs, and the emergent trend of keeping DGs in PDSs during fault. The process of selecting FCL impedance type (inductive or resistive) and its minimum value is illustrated. Three scenarios are discussed: no DG, the implementation of DG with FCL and without FCL. Various simulations are carried out for both single- and multi-DG existence, and different DG and fault locations. The obtained results are reported and discussed. </para>

An Approach to Tackle the Threat of Sympathy Trips in Directional Overcurrent Relay Coordination

This paper proposes to introduce additional constraints in the directional overcurrent relay coordination problem to tackle the sympathy trips. This paper attempts to tackle the sympathy trips in which other relay(s) in the system operate(s) earlier in the designated primary relay. The solution to this problem requires the inclusion of some additional constraints, making the coordination problem too complex. This paper proposes to solve the problem in two phases. In the first phase, the problem is solved by a normal coordination procedure and sympathy trips are identified. In the second phase, the proposed additional constraints are imposed only for the sympathy trips identified in the first phase. For the second phase, three approaches for including additional constraints were investigated. This paper includes results of the proposed algorithm for the IEEE 30-bus system. The results amply suggest that one of the three approaches of including additional constraints successfully tackled the problem of sympathy trip

A New Nonlinear Directional Overcurrent Relay Coordination Technique, and Banes and Boons of Near-End Faults Based Approach

Considerations of weight factors and far-end faults in the directional overcurrent relay coordination problem formulation do not affect the optimal solution. This paper investigates this viewpoint and verifies that indeed by such an approach the optimality is not lost. But, this study reveals that in doing so, the coordination quality is sacrificed to some extent. It is also observed that if all remaining valid constraints (after relaxing few constraints based on the back-up coordination philosophy and strength of fault level generated) are considered and if the objective function is changed to running sum of all violating constraints, all valid considered constraints are satisfied. This study is done by simultaneously optimizing all settings in nonlinear environment by Sequential Quadratic Programming method using Matlab Toolbox. The results of the analysis on a sample 6-bus and IEEE 30-bus systems are presented in this paper.

Linear programming for directional overcurrent relay coordination in interconnected power systems with constraint relaxation

A linear programming method with constraint relaxation is applied to the directional overcurrent relay coordination problem in an interconnected power network. This method allows for hierarchical constraint relaxation and removal in cases where an infeasible problem exists. This method is applied to coordinate the directional overcurrent relays for an example interconnected power network with six buses and seven lines. Different suggestions for choosing the pickup current and the resulting time dial settings are presented. These results are compared with those given by the break-point approach. A complete algorithm for calculating the time dial settings corresponding to given pickup currents is introduced to make this method suitable for computer implementation.