A simple but powerful optimization method for coordination of over current (OC) relays is presented in this paper. For distribution system protection as well as backup protection in transmission system, overcurrent relay is most widely used. Maloperation of relays may occur if primary and backup relays are not properly coordinated. And therefore relay coordination become important part of power system protection. The main contribution of this paper is application of sequential quadratic programming (SQP) method for calculating optimum values of time multiplier setting (TMS) and plug setting (PS) of OCRs. The proposed algorithm was successfully tested on different systems. Comparison of results with genetic algorithm is also presented in this paper. From results it is found that SQP method is superior as compared to GA technique.

Optimal overcurrent relay coordination in distribution system using nonlinear programming method

This article proposes a new adaptive commissioning methodology for arc flash mitigation in steel manufacturer users considering the Tap-to-Tap varying current consumption. This process is achieved through adaptative protection settings computed to reduce the total clearing time of relays adding the restriction of the incident energy. The proposed methodology carries out the detection of abrupt changes in current consumption to detect Tap-to-Tap change in operation stages of electric arc furnaces. The application of this methodology is performed on a steel manufacturer user and shows the reduction of the incident energy values according to Tap-to-Tap operation cycle.

Adaptive Commissioning Methodology for Arc-Flash Mitigation in Steel Making Users

Microgrids comprise low voltage distribution systems with distributed energy resources (DER) and controllable loads which can operate connected to the medium voltage grid or islanded in a controlled and coordinated way [1]. Microgrids are controlled units which report their current state to a central control unit called Central Protection Centre (CPC) thus increasing reliability of the system. This feature also increases the controllability, security and ease of power flow. By connecting load centers to a microgrid, uninterrupted power is supplied to households and industries with reduction in energy theft, interruptions and loss in energy. However the challenge lies in automating the entire process of monitoring, protection and control of all the grid parameters. This becomes more critical with inclusion of DERs as they are inconsistent sources of energy. In this paper the concepts of Internet of Things(IoT) is used to solve the issues of microgrid reconfiguration occurring due to faults, changing energy usage patterns and inclusion and removal of DERs. By using suitable processor based technology it is aimed to automate the process, reduce the cost and size of establishment and reduce the overall cost of energy to the supplier.

IoT Based Microgrid Automation for Optimizing Energy Usage and Controllability

Series of devices are included in the power system networks for the safety of the people and components from faults. They are mainly required because high current may cause damage to devices in the system and people. The primary protection system and its backup with appropriate time grading ie the tripping time (maximum) for the point which is located very far from the actual location of the fault. Radial distribution networks often meet with overcurrent fault conditions. Hence, the utilization of overcurrent relays is a must for the protection of devices from high current faults. The major work of a protection engineer is to maintain coordination time interval among relays during overcurrent relay coordination. Thus Optimization algorithms are applied to relay parameters, so that the faults can be cleared in the minimum time. In this paper. Two Phase Simplex and Particle Swarm Optimization Algorithm are implemented on a two bus radial system for optimization of Time multiplier setting values (TMS values) which required for the coordination of overcurrent relays.

Optimal coordination of overcurrent relays using two phase simplex method and particle swarm optimization algorithm

Overcurrent (OC) relay plays a major role in power distribution system. It protects electrical power systems against excessive current which are caused by faults like short circuits, ground faults, etc. It is necessary to clear the fault within a least possible time. The optimum time coordination of overcurrent relay in distribution network solved using Differential Evolution method and Dual Simplex method is presented in this paper. These methods are used to find the optimized values of time multiplier settings (TMS) of relays using linear programming problem (LPP). Differential evolution considers the present existing constraints to form the optimized values using mutation mechanism. Dual simplex gives the optimum solution without introducing any artificial variables. Differential Evolution and Dual simplex technique are presented in this paper for optimum time coordination of OC relays in a radial fed distribution system.

Optimum coordination of overcurrent relays in distribution systems using differential evolution and dual simplex methods

Protection system includes a series of devices whose main purpose is to protect people and primary electric power equipment from the effects of faults. Fault currents cause damage to equipment and are also hazardous to personnel. Thus, there should be a primary and a backup system with proper time grading between systems, i.e. Tripping time should be maximum for the point farthest from the fault location. Over current (OC) relays are used as backup protection against these faults. The coordination time interval must be maintained among relays during faults. Various algorithms are used to optimize the time of operation of these OC relays. This paper implements Dual Simplex and Genetic Algorithms (GA) on a radial network and identifies the time multiplier setting (TMS) of the relay. This facilitates in achieving suitable OC relay coordination of the network.

Deepika Mewara

Papers

Optimum Coordination of Overcurrent Relays Using Dual Simplex and Genetic Algorithms