Relay Coordination Research Articles

Optimized Overcurrent Relay Coordination in a Microgrid System

Background: Microgrids are a conglomeration of loads and distributed generators at a distribution level network. Since this network is no longer a single source fed network, the typical protection strategies may not be deployed. Reconfiguration is a topology changing feature that is visible in microgrid. This is also another factor that is to be considered while protecting the microgrid setup. Objective: To develop an optimized overcurrent relay coordination scheme for microgrid networks. Methods: Inorder to devise suitable overcurrent protection scheme for microgrids, initially the normal and fault currents are captured for all topologies of the microgrid. For each topology, the optimized time multiplier settings of overcurrent relays are computed using Dual Simplex Algorithm. This aids in clearing the fault as fast as possible from the network. Results: A 21-bus microgrid system is considered and the optimized overcurrent relay coordination scheme is realized for the same. Conclusion: The proposed optimized overcurrent relay coordination was tested successfully on the 21-bus microgrid system. The proposed protection scheme was capable of identifying the optimized Time Multiplier Setting values of the overcurrent relays in the path of fault clearance. It is evident that the proposed scheme can be conveniently extended to larger networks.

Adaptive optimum coordination of overcurrent relays for deregulated distribution system considering parallel feeders

This paper proposes an adaptive optimum overcurrent protection for deregulated distribution networks containing parallel feeders. The proposed adaptive coordination eliminates the maloperation of conventional overcurrent protection under different fault scenarios. These scenarios take place when faults occur close to the end of the parallel feeders specially when faults are associated with significant fault resistances. Under these faults, the current at the backup relay is almost double that at the corresponding primary. Thus, adaptive pickup setting is recommended. However, this problem is complicated remarkably when distributed generation units feed the upstream source side faults or under the removal of the power source due to the interruption of a source side breaker. Simultaneously, the proposed coordination approach enhances the sensitivity and keeps on the optimum speed by automatically identifying the faulted zone. The faulted zone is identified by monitoring both the status concerning a single feeder or two parallel feeders in service and the faulted phase current direction of each pair of relays. Thus, a new fault direction identification method is presented. This method is based on comparing the angle of the post-fault current and that of the pre-fault current. Three optimization algorithms (genetic, harmony search, and water cycle algorithms) have competed to find the optimal settings of the installed overcurrent relays for each faulted zone. The reliability of the proposed method is examined as compared to conventional coordination concepts based on a detailed simulation of an actual 11-kV cascaded parallel series distribution feeder in the Egyptian distribution network. Sample results are examined.

Hybrid Harris hawks optimization with sequential quadratic programming for optimal coordination of directional overcurrent relays incorporating distributed generation

This paper presents a new hybrid algorithm of Harris hawks’ optimization with sequential quadratic programming (HHO-SQP) for optimal coordination of directional overcurrent relays to find optimal relays settings. The SQP procedure is employed in the hybrid algorism as a local search mechanism to enhance the performance of the original HHO method. The optimization problem is described based on a developed objective function as a non-linear and highly constrained optimization problem to minimize the total operating time for primary relays at the same time of maximizing the backup relays operating time. The developed objective function is subject to some constraints related to the coordination process including the absence of any miss coordination between primary and backup relays. The performance of the proposed algorithm based on the new objective function is implemented for two different test systems. The results of the proposed algorithm is compared with those obtained from other recent meta-heuristic techniques. The results show that the new hybrid algorithm outperforms the recently published meta-heuristic algorithms.

An adaptive characteristic for overcurrent relays considering uncertainty in presence of distributed generation

Changing the operation mode of the sources leads to change in the fault current passing through overcurrent relays, their operating time and relay pairs coordination. In this paper, a new adaptive method is proposed to maintain the coordination of overcurrent relays under uncertainty of the presence of DGs in a distribution network. In this method, the relay settings are first calculated in the base structure (in the absence of DGs) and coordination is established. The fault currents of the new structure are then calculated from the Thevenin equivalent circuit. The Thevenin equivalent circuit is determined from the relay point of view using voltage and current measured at the relay location before a fault occurrence. Adaptive coefficients are then defined as ratios of the base structure fault currents to the new structure fault currents. Using these adaptive coefficients, the fault currents in the new structure are converted into the equivalent values in the base structure, and the coordination of relay pairs is maintained. The proposed adaptive relays coordination is compared with the conventional relays coordination in networks with radial, ring and mesh configurations. The simulation results show the superiority of the proposed method in maintaining coordination.

WITHDRAWN: Coordination of IDMT relays in the radial distribution system with distributed generation

Abstract Relay coordination is one of the most significant and difficult task in Radial Distribution System. The Radial Distribution System interconnected with the Distributed Generation like solar PV system and wind generator. It carries new challenges in standard protection systems and their coordination losses in between primary and backup relays. In this system relay pickup currents and time multiplier settings are changed for proper relay coordination. In this paper a method has been proposed for appropriate relay coordination and has been analysed for the test system. The IEEE-13 bus system has been considered for the proposed method. Mi-Power software is used for the simulation purpose.

Mitigating the Impact of Distributed Generations on Relay Coordination Using Fault Current Limiters

Mitigating the Impact of Distributed Generations on Relay Coordination Using Fault Current Limiters

Protection Coordination of Bidirectional Overcurrent Relays Using Developed Particle Swarm Optimization Approach Considering Distribution Generation Penetration and Fault Current Limiter Placement

This article is treated with the protection coordination of bidirectional overcurrent relays (OCRs) in distribution power systems to obtain the best performance at a minimum total time dial setting (TDS). High penetration of distribution generation (DG) into distribution systems may significantly affect the protective system; since they increase the short-circuit level by injecting an extra share of fault current, it results in changes in the power/current flow direction. Accordingly, the fault current limiter (FCL) devices should be utilized to mitigate the short-circuit current. FCLs and DGs both will disturb the protection settings of protective equipment. The characteristics and the set point of inverse time relays depend on the fault clearing time (FCT) and the pick-up current. Therefore, an optimization approach is required to minimize the FCTs and TDSs of main relays and backup ones to protect all equipment. Moreover, this strategy selects the optimal placement of the FCL cooperatively according to the cost minimization. The optimization approach is implemented based on the particle swarm optimization (PSO) method within an extra parameter to improve the convergence speed and find the global solution, especially at initial iterations. The proposed optimization approach named developed PSO (DPSO) is tested on the IEEE 14-bus system and compared with some existing methods. Finally, the analysis and evaluations present the effectiveness of the best current transformer (CT) settings with the minimum response time.

Optimal Coordination of Directional Overcurrent Relays in Meshed Active Distribution Network Using Imperialistic Competition Algorithm

The optimal setting of directional overcurrent relays (DOCRs) ensures the fault detection and clearing in the minimum possible operation time. Directional protective relaying is carried out to coordinate relay settings in a meshed network in the presence of distributed generation. The main goal of DOCR coordination is to find the optimal time dial setting (TDS) and pickup multiplier setting (PMS) to reach the minimum total operation time of all primary relays in the presence of coordination constraints. Due to the complexity of mixed integer non-linear programming (MINLP) problem, imperialistic competition algorithm (ICA) as a powerful evolutionary algorithm is used to solve the coordination problem of DOCRs. The proposed DOCR coordination formulation is implemented in three different test cases. The results are compared with the standard branch-and-bound algorithm and other meta-heuristic optimization algorithms, which demonstrates the effectiveness of the proposed algorithm.

New Overcurrent Relay Coordination Method Through Time Intervals to Enhance Microgrid Protection

New Overcurrent Relay Coordination Method Through Time Intervals to Enhance Microgrid Protection

Optimal Protection Coordination Scheme for Radial Distribution Network Considering ON/OFF-Grid

Technology advancement for renewable energy resources and its integration to the distribution network (DN) has garnered substantial interest in the last few decades. Integrating such resources has proven to reduce power losses and improve the reliability of DN. However, the growing number of these resources in DN has imposed additional operational and control issues in voltage regulation, system stability, and protection coordination. Incorporation of various types of distributed generators (DG) into DN causes significant changes in the system. These including new fault current sources, new fault levels, a blinding effect in the protection scheme, reduction in the reach of relays, and decrement in the detection of low-level fault currents for existing relays. Such changes will jeopardize the effectiveness of the entire protection scheme in the DN. This research aims to propose a robust protection scheme in which the relay coordination settings are optimized based on the network layout. The potential impacts of DGs on the DN are mitigated by utilizing a user-defined overcurrent-based relay characteristic to obtain the minimum operating time while satisfying protection coordination constraints. A hybrid optimization algorithm based on Metaheuristic and Linear Programming that has the capability to attain the optimal solution and reduces computational time is proposed in this work. The performance of the proposed technique is tested on radial DN integrated with microgrid (MG). The results obtained show the proposed technique has successfully reduced the relay operating time while meeting the protection coordination requirements for dynamic operating modes of a network.

Optimal coordination of over-current relays in microgrids considering multiple characteristic curves

Nowadays, microgrids play a significant role in the development of modern distribution networks (DNs). In this context, the ever increasing presence of renewable distributed generation (DG) in microgrids has imposed new challenges in protection coordination, rendering traditional coordination schemes inefficient. Thus, it is essential to explore new approaches for protection coordination that take into account specific features of microgrids, such as the presence of DG and the fact that they may operate under different operational modes or topologies. This paper proposes a novel approach for the optimal coordination of over-current relays (OCRs) in microgrids that considers three optimization parameters for each relay: time multiplying setting, plug setting current and characteristic curve. To show the applicability of the proposed approach, several tests were carried out using an IEC benchmark microgrid and a modified version of the IEEE 30 bus test system. Three metaheuristic techniques were implemented for solving the optimal coordination problem, namely: a genetic algorithm (GA), particle swarm optimization (PSO) and a teaching–learning based optimization (TLBO) algorithm. A comparison of results with other coordination models reported in the specialized literature evidenced the applicability and effectiveness of the proposed approach.

Adaptive relay settings for distribution network with distributed generation (DG) using Sugeno fuzzy inference

Abstract The rapid increase in the power demand and the capacity shortage of transmission and distribution system drives the integration of Distributed Generation (DG) units in electrical power distribution networks. The integration of DG resources with distribution network can cause significant impacts in protection due to the bidirectional flow of current, particularly the changes in magnitude and direction of short circuit currents. It may also lead to false tripping or fail to trip the over current protection relays in the power system. The relay parameters have to adapt to the changes in the system to avoid unnecessary trippings. The proposed adaptive over current protection scheme, sets the parameters of the relays according to the changes in the network. This method determines the plug multiplier settings (PMS) and the time multiplier settings (TMS) using Sugeno Fuzzy Inference System (SFIS). The proposed methodology is tested for IEEE 13 bus system and 33 bus system and with the obtained adaptive relay settings, the validation for relay coordination is done using ETAP.

Adaptive Protection Scheme for Microgrid With Multiple Point of Common Couplings

Frequent changes in operating conditions of microgrid affect the coordination of directional overcurrent relays (DOCRs). This article proposes an adaptive protection scheme to handle DOCRs coordination problem in microgrid having multiple point of common couplings. The proposed scheme consists of two blocks: offline and online. In offline, settings of DOCRs are calculated for most important operating conditions (grid connected and islanded modes) and stored in corresponding DOCRs. The online task is performed based on local and global decision approaches. The local decision approach ensures significant less burden on microgrid central controller. Also, the proposed scheme does not cause any catastrophic conditions in microgrid when a fault occurs during critical situations. Then, coordination problem is formulated as constrained nonlinear programming problem and solved using a symbiotic organism search algorithm. The effectiveness of the proposed scheme is examined on 7-bus and IEEE 33-bus microgrids during various operating conditions. Furthermore, simulation results are validated on hardware-in-loop test bed using real-time digital simulator, numerical relays, and CMS-356 (voltage and current amplifier). From simulation and hardware results, it is noticed that proposed scheme is able to provide an adequate protection to microgrids during various operating conditions, various types of bolted faults, and high-impedance faults.

Optimal directional overcurrent relay coordination using MRFO algorithm: A case study of adaptive protection of the distribution network of the Hatay province of Turkey

Coordination of Directional Over Current Relays (DOCR) is an important issue in the protection of power systems. In this paper, the object function of DOCR has been modified for better coordination. Manta Ray Foraging Optimization (MRFO) algorithm is adapted to the DOCR with the modified object function to maintain optimum relay coordination by preserving the relay coordination margin between the relay pairs. In order to show the success of the proposed technique, the algorithm has been applied to the 9-bus and 15-bus test system. The obtained results have been compared to other algorithms in the literature. Further, an adaptive protection structure, which provides optimum coordination of DOCR with MRFO algorithm according to changing power system conditions, has been proposed for a network that include Distributed Generation (DG) power plant. The proposed adaptive protection structure has been applied to the virtual model of a cross-section of 10 bus distribution networks that includes a Wind Powered DG (WP-DG) in the Hatay province of Turkey.

Peer Review of Renewable Energy-based Adaptive Protection(s) & Relay Coordination Optimization Techniques

Background: Distributed Sustainable Energy Generation (DSEG) has become a leading trend in modern R&D to achieve practical, financial, and environmental benefits. With respect to the power system, the benefits are minimization of power failures, enhancement of energy quality & reliability, congestion relief, and smart/micro grid demand response. The widespread use of modern technologies encourages the use of DSEG for safe power production and power loss reduction. Besides, it also poses new challenges such as optimal placement of relays, protection device settings, and voltage control problems in power systems. : Among various solutions reported in the literature, a widely accepted solution seems to be the deployment of Fault Current Limiter (FCL) to minimize DSEG impacts. However, FCLs are an expensive option to restore relay coordination. The adaptive protection scheme provides benefits to the smart grid's advanced features and serves as an efficient solution to address new DSEG and FCL challenges. Objective: This paper presents an extensive review of the effect of DSEG on distribution systems from the safety point of view, different optimization techniques used for adaptive protections, optimal relay coordination, and merits & demerits of FCL. Methods: The paper discusses various recent optimization and hybrid optimization techniques used for solving the Optimal Relay Coordination model (ORC). Adaptive and FCL based non-adaptive techniques are also discussed to solve this model. An attempt has also been made to present a comparative study of various optimization techniques in tabular form, considering different bus models and their outcomes. Conclusion: Comparative study of these techniques shows that Water cycle optimization, hybrid whale-GWO and GSA-SQP algorithms give better results in solving the ORC problem. FCL based non-adaptive technique was found better as compared with adaptive techniques because a greater number of DGs can be integrated on a grid with less complexity.

Effect of renewable energy sources integration on the optimal coordination of directional over-current relays in distribution system

<div data-canvas-width="397.21009877040933">The demand for power electricity is growing fast and one of the main tasks for power engineers is to generate electricity from renewable energy sources (RES).</div><div data-canvas-width="277.2073926627698">Nevertheless, problems arise when the new generation is integrated in the power distribution network. Under this condition, the main purpose in this paper, an investigation of the effect of RES integration on the optimal coordination of directional over-current relays in distribution system, a dual simplex optimization algorithm has been presented to determine the coordination of directional over-current relays (DOCRs). The system used to check the efficiency of the optimization algorithm which is IEEE 33-bus models. The analysis is performed in MATLAB software environment.</div>

Effect of renewable energy sources integration on the optimal coordination of directional over-current relays in distribution system

Effect of renewable energy sources integration on the optimal coordination of directional over-current relays in distribution system

Wind generator protection with ESSs considering grid connected and island mode operations

This paper proposes a novel scheme to protect a Wind Generator (WG) with Energy Storage Systems (ESSs). In the scheme, data are dealt with in an iterative way to obtain the relay coordination considering both generator operating modes: grid connected and island. The proposition relies on conventional protection functions adapted to the operational system requirements. A set of well-known protection functions (under-voltage, over-current, differential and unbalance) operating together in an innovative arrangement, was the main objective of this research. In order to validate the proposed scheme, a Wind Energy Conversion System (WECS) with a Vanadium Redox Flow Battery (VRFB) as an EES was implemented in a real time digital simulator (RTDS®) to perform hardware-in-the-loop simulations. The simulation system consisted of a Wind Generator with grounded stator connected to the system through a DC link in order to investigate its behavior subjected to internal and external faults. Very promising results considering the proposed scheme are presented.

Optimizing the protection coordination of DGR (Directional Ground Relay) to overcome sympathetic disturbances and reduce energy not supplied on Toboali Substation

Along with the operation of the Toboali Substation, studies needed to improve reliability. The ground disturbance that occurs in a feeder can cause a sympathetic trip in another feeder and effect the blackout of Toboali system. This is due to the choice of loop operating patterns on feeders and buses that tend to be close together. From the results of simulation and optimization of directional ground relay coordination it was found that before the improvement of energy not supplied due to sympathetic disturbances on the Toboali system was 51,261 MWh/year and after the improvement of energy not supplied became 21,170 MWh/year. Expected this optimization of protection coordination improves reliability and reduces the energy not supplied due to sympathetic disturbances that occur in Toboali substation.

Integration of wind turbines in distribution systems and development of an adaptive overcurrent relay coordination scheme with considerations for wind speed forecast uncertainty

The integration of renewable energy (RE)-based distributed generation (DG) with electric power distribution systems (DSs) in association with smart grid technology has numerous benefits, however, due to their intermittent nature, the utilisation of RE-based DG may pose threats to the proper operation of conventional overcurrent (OC) protection schemes. The resulting threats, malfunctions, and non-selective actions could occur by relays within the DS, and the development of efficient protection schemes is necessary. The objective of this study is to propose and simulate an adaptive OC protection scheme in DSs in the presence of doubly-fed induction generator (DFIG) wind turbines based on wind speed forecast data with considerations for wind speed forecast uncertainty and a low-voltage ride-through requirement for wind turbines. In each time interval and possible operating mode, the output power of DFIG-based wind turbines and relay setting parameters are determined offline. The results show that the proposed protection scheme prevents malfunctions and non-selective operations of relays, and also provides faster fault isolations, as compared to the conventional OC protection scheme.