Miscoordination of relay in radial distribution network containing distributed generation

Due to the fast-paced changing technologies in the field of electricity market liberalization, the incorporation of Distributed Generation (DG) along with its various distributed resource technologies have led to a profound change in electrical power system. Besides many positive impacts of incorporation of DG into the electrical power system, it has introduced many inherent technical problems such as miscoordination, reliability degradation and stable islanding. This paper originates from the report of IEEE Power System Relaying Committee and on having observed the malfunctioning of Electricity boards by the authors at local and regional level due to DG interconnections with regards to the miscoordination of relay. A laboratory prototype of three phase radial distribution network containing DG is presented in this paper. By executing number of single line-to-ground faults at different locations in various sections of radial distribution network containing DG, numbers of maloperations due to miscordination of relay have been observed by the authors. Time of operations of all the relays of radial distribution network obtained from the developed laboratory prototype for different fault locations in various sections have been found to be in close conformity with the theoretical values obtained using an IEC standard relay characteristics equation.