ISLANDING DETECTION IN DISTRIBUTED GENERATION

Abstract

Because of increasing environmental pollution and the rapid extinction fossil fuel, the distributed generation resources demand increases. Distributed generation resources (DGR) consist of wind power, solar photovoltaic and fuel cell which enhances the efficiency of the distribution network and power system network. But due to steady state and dynamic behavior of DGR it impose a challenge of control and protection of distribution network. Islanding of the distribution network is one of the major challenges in distributed generation(DG). Islanding is a situation when a portion of distribution network which consist distributed generation resources is electrically isolated from the utility grid but still distributed generation resources are supplying power to local loads. Efficient and rapid islanding detection and immediate disconnection of DGs is essential in order to avoid equipment damage, grid protection interference, and personnel safety hazards to individuals. Islanding detection techniques are categorised into three different groups i.e., passive, active and communication based techniques. Passive techniques have more advantages over other as it causes lower power quality degradation, lower cost, and hence has widespread usage by power utilities. The main drawback of this technique is that it possess a large non detection zones. A new islanding detection technique is proposed for detecting islanding in distributed generation with the help of rate of change of negative sequence voltage and current. In the proposed technique the voltage and current is measured at targeted DG. The obtained voltage and current are then converted into symmetrical component through sequence analyzer. The rate of change of negative sequence voltage (ROCONSV) and rate of change of negative sequence current (ROCONSC) are calculated by negative sequence component. The proposed technique is very fast acting as it detects islanding very fast (within 2sec.).