Directional Overcurrent Relays Research Articles

Quadratic programming-based semi-deterministic approach to find optimal settings for the directional overcurrent relays with user-defined characteristics

Quadratic programming-based semi-deterministic approach to find optimal settings for the directional overcurrent relays with user-defined characteristics

Optimizing directional overcurrent relay coordination with jellyfish search algorithm

Optimizing directional overcurrent relay coordination with jellyfish search algorithm

Optimizing DOCRs coordination when synergizing energy management with V2G using innovative optimization algorithms

This manuscript proposes an optimal coordination approach for directional overcurrent relays (DOCRs) within electric vehicle charging stations (EVCS), considering energy management and Vehicle-to-Grid (V2G) integration. The study focuses on maximizing efficiency and grid interaction in charging stations by addressing the challenge of DOCRs coordination. Three innovative optimization algorithms, namely the Hunger Games Search (HGS), Hunter Prey Optimization (HPO), and Sparrow Search algorithm (SSA), are employed to determine the optimal coordination for the DOCRs and get the time dial setting (TDS) and pickup current (IP) targeting minimum operating time for all DOCRs, considering factors such as load balancing, fault detection, and power quality in three different scenarios. EVSC has two types of charges DC and AC with two modes: V2G mode when EV is discharged into the grid, and G2V mode when EV is charged from the grid. Fast chargers are used to proceed as it can work in two modes V2G and G2V. Through extensive simulations and performance evaluations, the results demonstrate the effectiveness of the proposed approach. The three scenarios are simulated by using ETAP and MATLAB software according to fault location and to achieve voltage regulation and sufficient power for loads to achieved continuity of service for up to 1960.7 kW loads that kept fed. The proposed approach achieved the target of protecting the EVCS in minimum operating time of relays using the three algorithms and SSA introduces the best result more than other algorithms for the relay operating time with reduction up to 21 %.

Integration of Artificial Intelligence for Enhanced Coordination of DOCR Protection in Distributed Generation Systems

Distributed generation (DG) is an approach that involves adding decentralized power generation within a distribution network. Distributed generation systems can reduce transmission losses, increase the reliability of energy supply, minimize carbon emissions, and enable the active participation of consumers in energy production. However, with the increase in distributed generation, electric power systems face new challenges in maintaining operational reliability and safety. Disruptions such as short circuits or overcurrent can occur in the system, and appropriate protective responses are required to protect the power grid from more significant damage. The addition of DG also causes the short circuit current to vary and results in system protection coordination having to be redone. Carrying out coordination will take a long time. This research uses modeling and simulation of a distributed generation system with various operating conditions and works adaptively according to changes in the system due to the addition of DG. The results obtained from the simulation are used in neural network training to study the relationship patterns between directional overcurrent relays (DOCR) parameters and system operating conditions. The backpropagation algorithm is used in the Artificial Neural Network (ANN) training process. The training process utilizes the maximum Short Circuit Current (ISC) input obtained through generation, fault location, and fault type. Time Dial Setting (TDS) and Ipickup values are used as ANN training targets. After testing, the results obtained are in accordance with the target data. The efficacy of this method is further demonstrated through ETAP simulations, which confirm that ANN is a suitable approach for modeling adaptive and optimal relay coordination systems.

Design of adaptive protection coordination scheme using SVM for an AC microgrid

Microgrids have gathered a significant amount of attention within the past decade and becoming an essential asset in the energy industry. The ability to integrate sustainable renewable energy generation into the distribution network is one of the main reasons for microgrids' popularity. Besides technical advantages, renewable energy sources integration with the grid poses many technical challenges. Due to randomness in generation and different modes of operation, integrating renewable energy sources into power systems will be challenging. Reliable operation of renewable energy sources integrated microgrids even when faults occur, requires an adaptive protection scheme and relay coordination. In order to tackle those issues, this paper developed an adaptive protection coordination scheme using numerical overcurrent relays and support vector machines with a particle swarm optimization approach. Renewable energy sources based on microgrids use power electronics systems that require relays to operate in milliseconds, and the power system will be safe. particle swarm optimization's program execution time exceeds the primary relays. The machine learning algorithm is faster in computation time. This article proposes a method, particle swarm optimization, to estimate the optimum relay operating time. The machine learning model having a support vector machine is proposed to estimate the relay operating time. The proposed research is developed and tested on an IEEE12BUS and IEEE35BUS system. The support vector machine -based on adaptive protection coordination schemes estimates the operating time of directional overcurrent relays, with a lesser program execution time and a low percentage error rate. The derived result defined that the proposed approach is well-suitable for real-time applications of an AC microgrid system.

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.

Coordination of Directional Overcurrent Relays using Growth Optimizer

The protection system plays a crucial role in the generation, transmission, and distribution systems of a power network. Among various protection relay types, Directional Overcurrent Relays (DOCRs) are the most used. When abnormal conditions are detected, these relays trigger the tripping of protection devices by detecting the direction and magnitude of current flow and isolating faulty parts of the system. The present article proposes a novel approach for the coordination and settings of DOCRs using the Growth Optimizer (GO) algorithm; the main objective is to minimize the sum of operation time of the relays while ensuring the minimal time gap between primary and backup relays. This optimization problem is subject to different constraints including maximum allowable operating times, relay coordination margins, and discrete values for pickup current settings. The technique is applied to the IEEE 4-bus, 8-bus, and 15-bus test systems, and its performance is compared with that of other optimization algorithms. Results show that the proposed approach provides the proper coordination of protection systems with a high, robust, and computationally acceptable speed of convergence.

Optimal overcurrent relay coordination: Balancing costs, time performance and generator placement in fault current limiter optimization

AbstractThe integration of synchronous generators (SG) to the grid will present serious problems in some instances. The increase in fault current level is one of the most crucial issues, which causes miscoordination between directional over current relays (DOCRs), in addition to putting excessive pressure on the circuit breakers. This research uses the Fault Current Limiters (FCL) to restore coordination, without changing the settings of DOCRs, by reducing the level of fault current in the grid. The main goal of this research is to find the optimal size, location, and number of FCLs at the minimum cost and with the least operation time for the relays, using Jellyfish Search Optimisation (JSO) algorithm. This can be achieved through three different approaches. The first one is optimizing the location, number, and impedance size of the FCL by minimising a cost function. The second approach involves optimizing the backup relay operation time. A combination of the two previous approaches is used as the third approach. The outstanding feature of this research is that it considers the optimal location of DG and FCL while optimizing the operation times of DOCRs, which is a new framework.

An adaptive protection coordination for microgrids utilizing an improved optimization technique for user-defined DOCRs characteristics with different groups of settings considering N-1 contingency

Due to the increased integration of distributed generation (DG) in electric power systems, optimal coordination of overcurrent relays has become a key problem in power distribution systems. However, there is a lack of expertise in the creation of optimum microgrid coordination that takes into account all N-1 scenarios through the nonstandard relay characteristics. This work presents a novel technique for optimal coordination of directional overcurrent relays (DOCRs) in terms of relay curve settings (A and B), time dial setting (TDS) and plug setting (PS) to achieve the shortest running time and attain optimal settings. The optimization is carried out using a modified version of the Hanger Games Search algorithm (MHGS). The performance of the proposed method is assessed using the 14 bus distribution system while considering all the N-1 contingencies. DIgSILENT software was utilized to perform the required power system analysis, such as power flow and short circuit analysis. The MHGS method is used to determine the best settings for the DOCRs problem. The results are compared to the traditional HGS as well as those obtained by other current optimization approaches provided in the literature in order to demonstrate the effectiveness and superiority of the proposed MHGS in lowering relay operation time for optimum DOCRs coordination.

Particle Swarm Optimization for Directional Overcurrent Relay Coordination with Distributed Generation

The Directional Overcurrent Relays (DOCRs) Coordination with Distributed Generation (DG) optimization problem is addressed in this study using the optimization method Particle Swarm Optimization (PSO). Changes in fault current, bus voltages, power flow, and reliability may result from DG integration. Thus, it might have an impact on the current protection coordination system. The formulation is built on a Mixed Integer Non-Linear Programming (MINLP) problem to address this DOCR issue. MATLAB was used to validate the technique on the IEEE-14 bus system, and Electrical Test Transient Analyzer Programming (ETAP) version 2021 software was used to model the test system. According to the simulation results, the suggested PSO with DG for Case 2 has reduced power loss by 6.24% and relay operating time by 46.79% when compared to PSO without the presence of DG.

Optimization Techniques for Directional Overcurrent Relay Coordination: A Comprehensive Review

Optimization Techniques for Directional Overcurrent Relay Coordination: A Comprehensive Review

Microgrid Protection Coordination Considering Clustering and Metaheuristic Optimization

This paper addresses the protection coordination problem of microgrids combining unsupervised learning techniques, metaheuristic optimization and non-standard characteristics of directional over-current relays (DOCRs). Microgrids may operate under different topologies or operative scenarios. In this case, clustering techniques such as K-means, balanced iterative reducing and clustering using hierarchies (BIRCH), Gaussian mixture, and hierarchical clustering were implemented to classify the operational scenarios of the microgrid. Such scenarios were previously defined according to the type of generation in operation and the topology of the network. Then, four metaheuristic techniques, namely, Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Invasive Weed Optimization (IWO), and Artificial Bee Colony (ABC) were used to solve the coordination problem of every cluster of operative scenarios. Furthermore, non-standard characteristics of DOCRs were also used. The number of clusters was limited to the maximum number of setting setting groups within commercial DOCRs. In the optimization model, each relay is evaluated based on three optimization variables, namely: time multiplier setting (TMS), the upper limit of the plug setting multiplier (PSM), and the standard characteristic curve (SCC). The effectiveness of the proposed approach is demonstrated through various tests conducted on a benchmark test microgrid.

Adaptive harmonic-based protection coordination for inverter-dominated isolated microgrids considering N-1 contingency

Protection coordination is typically approached considering the main network configuration. Nevertheless, contingencies such as generator or line failures may disrupt power grids. Low fault currents in inverter-based isolated microgrids adversely impact the conventional overcurrent protection schemes. This paper proposes a sensitive and selective protection scheme for isolated microgrids using an adaptive third harmonic voltage generated by inverter-based distributed generators (IBDGs) and adapted to fault severity. The generated harmonic voltage results in a harmonic layer established during faults and is decoupled from the fundamental fault current, which is limited by IBDGs. Harmonic directional overcurrent relays sense the generated harmonic currents and voltages at the relay location to ensure optimal protection coordination (OPC). The OPC problem is formulated as a constrained nonlinear program to determine the optimal relays’ settings. The constraints are defined for the isolated configuration and each potential configuration resulting from an N-1 contingency. A radial microgrid that is part of a Canadian urban distribution network is used to ensure the successful operation of the proposed protection scheme. The results demonstrate the ability of the proposed scheme to protect isolated microgrids and preserve protection coordination without communication.

Exploring the interdependence between control and protection philosophies in inverter integrated power system: A case study on directional relaying schemes

The potential impacts of the inverter-interfaced renewable energy resources (IIRERs) on the performance of sequence-based directional relaying schemes (SBDRS) have been investigated in this paper. The directional overcurrent relays such as 67POS, 67NEG, 67ZERO and 32Q have been considered for the investigation. CIGRE-14 bus system with IIRERs along with detailed modeling of inverter control scheme (with and without grid codes) and SBDRS have been done in the PSCAD environment. The mathematical analysis and circuit realization of the IIRERs have been attempted in the paper. The exclusive fault characteristics exhibited by IIRERs cause the conventional SBDRS to mal-operate. Significant change in levels of sequence currents and angular relationships between sequence voltages and currents during faults contributes to relay's unpredictable behavior. The comparative study based on different fault types, fault resistances and interconnecting transformer connections have also been done. The study reveals the impact of non-generalized angular differences between positive sequence voltage and current at the inverter terminal on performance of 67POS. It is found that 67NEG and 32Q mal-operated for all types of unbalanced faults while the 67ZERO can be utilized for grounded fault with delta-star grounded connection of interconnecting transformer.

Overcurrent and Directional Overcurrent Protection for Microgrid

Microgrids will become common in future electrical distribution networks. Numerous operating modes that occur in microgrids make the development of protection schemes and settings challenging. This paper aims to develop a simple protection scheme for the Microgrid IEC Benchmark without any expensive equipment such as communication apparatus. The scheme consists of directional and non-directional overcurrent relays with standard inverse characteristics. For the simulation tool, Digsilent powerfactory is employed. Four operating modes of the microgrid are applied to verify the relays’ coordination. The results show that the proposed scheme successfully protects the microgrid during short circuit faults with acceptable time margins.

The Research on the Improvement of the Zero-Sequence Relay for the Low Resistance Grounded Power Grid

In the low resistance grounded power grid, when a high-impedance grounding fault occurs at a distribution line, the zero-sequence fault current is not big enough to make the zero-sequence over-current relays trip because of the setting limitations, and thus the earth fault would exist for a long time with no alarm signal. As a result, there would be a hidden danger that the grounding fault might cause further faults or cause harm to personal safety. To solve the problem, in the paper, the characteristics of zero-sequence components when the high-impedance grounding fault occurs are analyzed, and the practicability and the deficiency of the directional zero-sequence over-current relay are pointed out. Based on the analysis, an improved zero-sequence relay with the resistance-capacitance ratio restriction is raised. The resistance-capacitance ratio restriction condition is based on the different structures of the resistant part and the capacitive part of zero-sequence currents, and the faulted line can be identified with the resistance-capacitance ratio criterion. The resistance-capacitance ratio criterion is not influenced by the polarity of the voltage transformer (VT) and current transformer (TA) and can avoid the influence caused by the reversed polarity of the exclusive zero-sequence TA. With the improved zero-sequence over-current relay with the resistance-capacitance ratio restriction, the ability to identify high-impedance grounding faults can be improved, and the fault area can be isolated quickly, to guarantee the reliability and safety of the operation in power grids.

An adaptive protection method with directional overcurrent relay coordination using hybrid chaotic artificial humming bird optimization

An adaptive protection method with directional overcurrent relay coordination using hybrid chaotic artificial humming bird optimization

Reconfiguration of the real distribution network and providing a new resilience index, considering the uncertainty of renewable energy sources and digital protection devices in order to improve the resilience

Electric energy, as the most widely used form of energy, has always captured human attention to itself; however, with the climate change and the increase of natural phenomena, it is now necessary to provide solutions to improve the resilience of the network. Resilience is defined as the capability of the system to maintain an acceptable level of performance against a severe disturbance and return to its original condition in an appropriate period of time, which demonstrates the degree of endurance, vulnerability, and reversibility of an infrastructure system. The occurrence of adverse weather conditions and natural disasters causes extensive losses and power outages in distribution networks; and the number and severity of such incidents have seen an increase in recent years. Therefore, it is of great significance to evaluate the resilience of the network and its reversibility capability in dealing with adverse weather conditions. In this paper, after defining the concept of resilience in distribution networks, its characteristics are determined; and then, modeling common natural events such as floods and storms, and introducing a new index to evaluate resilience in distribution networks with digital directional overcurrent relays (DOCR) and Digital dual-setting directional overcurrent relays (DS-DOCR) in the presence of renewable energy sources (RES), the proposed scheme is presented.

Optimal Protection Scheme for Enhancing AC Microgrids Stability against Cascading Outages by Utilizing Events Scale Reduction Technique and Fuzzy Zero-Violation Clustering Algorithm

The precision with which directional overcurrent relays (DOCRs) are set up establishes the microgrid customers’ access to reliable and uninterrupted electricity. In order to avoid failure in DOCRs operation, it is critical to consider a single contingency (N-1 event) on the protection optimization setting problem (POSP). However, power systems may face cascading outages or simultaneous contingencies (N-K events), which greatly expand the problem’s complexity and scale. The effect of cascading events on this problem is an open research gap. Initially, this paper proposes a novel approach to reducing the scale of simultaneous events called the N-K events scale reduction technique (N-K-ESRT). Moreover, an innovative method named fuzzy zero-violation clustering is utilized to group these contingencies. Ultimately, the DOCRs’ decision parameters are generated by three optimization algorithms, namely interior point (IPA), simulated annealing, and pattern search. In all case studies (including a real industrial network called TESKO2 feeder, the IEEE Std. 399-1997, and the IEEE 14 bus systems), the capabilities of the proposed method are effectively validated based on the DOCR’s tripping time and the algorithm’s execution time.

Communication-less adaptive directional overcurrent protection strategy considering islanded mode detection in active distribution networks

The integration of distributed energy resources (DERs) in electric distribution networks originates the Active Distribution Networks (ADNs). The presence of DERs introduces challenges to conventional protection schemes due to bidirectional power flows and variations in fault current magnitudes; furthermore, the connection and disconnection of DERs result in multiple ADN operating modes (OMs), deteriorating the effective operation of protective relays. Considering the above, this document presents an adaptive protection strategy to address the challenges related to the variable nature of the ADN operation. The main contribution of the proposed approach is accurate islanded mode detection without requiring communication links, enabling fault detection in all ADN operating modes. The protection strategy maintains directional overcurrent relays' coordination using local voltage and current measurements to continuously estimate the Thevenin equivalent, fault currents, and adaptive coefficients.Relay coordination is maintained through tests conducted on a modified IEEE 34-bus feeder, considering several OMs, fault types, and locations. A comparison between the proposed adaptive protection strategy and a conventional overcurrent scheme shows that relay operating time is better in 100% of the analysed cases for the former strategy. On the other hand, the maximum errors in the fault current estimation using the Thevenin equivalent parameters are between 0.05% to 2.6% for all of the analysed operating modes when compared with the true fault current magnitudes. Finally, the adequate results validate the potential of the proposed communication-less protection strategy for modern protective relaying applications.