Reducing the impact of DG on distribution networks protection with reverse power relay

Abstract

The assimilation of distributed sources in to existing distribution networks (DN’s) will bring up the several technical, economical and regulatory questions. Conventional distribution system is radial in nature, characterized by a single source feeding a network of downstream feeders. Therefore the voltages decrease towards the end of the feeder from the source, The incidence of distributed generators (DG) in the distribution networks alter the radial nature of distribution, causes the power flow in reverse direction in the event of DG is added in a system, or any fault in the feeding source/end, the DG exceed the local load, that is, towards the high voltage grid, it causes the existing protection system fails to protect the distribution networks against these changes.To solve this problem reverse power relay (RPR) is proposed to protect the system voltage fluctuations, power reversals condition. The proposed Reverse power relay is a directional power relay it monitor the power flow from a generator (centralized) running in parallel with another generator (DG) or the utility. The reverse power relay prevents a reverse power in the network by disconnect the DG from the distribution network under faulted condition. It also estimates the reverse power and proposes corresponding adjustment value to provide solution to protect distribution network as per the relay settings and distribution system changing scenario. The simulations have been performed using mat lab/simulink.