Coordination of over current relay for sudden rise of input energy in renewable power system

There are several new and renewable energy sources including hydro-, solar-, wind-power generation and etc., but the relay coordination is performed regardless of the characteristics of each new and renewable energy source. In this paper, the pickup and instantaneous current and the time delay of the over-current relay (OCR) is reviewed firstly, which was already coordinated for the wind power system. And the problem of frequent operation of OCR coordinated equally regardless of the characteristics of the renewable energy source is analyzed and an alternative is proposed. The coordination criteria applied for OCR in this paper is based on the standard of the Korea Electric Power Corporation (KEPCO) and the characteristic curve of OCR provided by the maker is applied. As a result of study, the number of operations of OCR can be reduced by re-coordinating the operation curve.