Coordination of Overcurrent Relay in Distributed System for Different Network Configuration

Niraj Kumar Choudhary,Soumya Ranjan Mohanty,Ravindra Kumar Singh

doi:10.4236/jpee.2015.310001

Niraj Kumar Choudhary, Soumya Ranjan Mohanty + Show 1 more

Open Access

https://doi.org/10.4236/jpee.2015.310001

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Abstract

This paper presents a study on protection coordination of over current relays (OCRs) in a distributed system by considering its different operating modes. Two different case studies which are considered in present work for protection coordination include: (i) DG interfaced distribution system in grid connected mode and (ii) DG interfaced distribution system in islanded mode of operation. The proposed approach is tested on the Canadian urban benchmark distribution system consisting of 9 buses. On the occurrence of fault, level of fault current changes which in turn changes the operating time of various OCRs. Therefore, it is important to calculate and suggest method of the relay setting in order to minimize the operating time of relays and also to avoid its mal-operation. In this paper, the protection scheme is optimally designed by taking into account the above mentioned conditions. The operating time of relays can be decreased and, at the same time, coordination can be maintained by considering the optimum values of time dial setting (TDS). Genetic Algorithm (GA) has been used for determining the optimum values of TDS and hence operating time.

Highlights

The increase in load demand is forcing the utility to use non-conventional energy resources like photovoltaic, wind energy, biomass etc
The prime objective of conducting this study is to investigate the impact of distributed generators (DGs) on fault current and how the coordination of overcurrent relays (OCRs) gets altered
A comparative study for protection coordination of OCRs is presented for different network configuration in presence and absence of DG

Summary

Introduction

The increase in load demand is forcing the utility to use non-conventional energy resources like photovoltaic, wind energy, biomass etc. These energy resources are an alternative which are used to decrease stress on the tra-. The distributed energy known as decentralized energy is generated with the help of small distributed energy resources (DER) or distributed generators (DGs). These distributed generators are generally integrated to the low/medium voltage level distribution network as the range of voltage which can be generated has some limitation. The main impact is in terms of bidirectional power flow and change in short circuit current level etc. [1]

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