Impact of distributed generation on protective relays

Abstract

The current power system is working under sustaining energy shortages. The distributed generation (DG) can be a solution for the energy shortage. Distributed generation refers to generation of power using a set of small sized generators that produces power at low voltage levels. The distributed generators are mainly designed to be connected directly to the distribution network near load centres. The distributed generation have some negative impacts in the power grid. DG is connected to the grid through power converters. These power converters results in power quality problems. The power quality problems include frequency fluctuation and harmonics which results in maloperation of relays. Many of the DG sources like wind, solar etc are intermittent in nature. The source impedance is varying in nature due to these intermittencies. The fault current characteristics are changing in the presence of distributed generation. Existing relay settings will not sense these change, which leads to maloperation of relays. The adaptive relaying can be a solution for the malfunction of relays. Adaptive relaying means the relay has to adapt to the changing environment. The decision making capability is to be incorporated with existing relays. The intelligence capability must be added to the relays.