Abstract:
Distributed generation (DG) may provide negative impacts to the connected distribution system. One important problem is the protection system miscoordination caused by the additional fault current from a DG which can increase the interruption event and the interruption duration. Therefore, this thesis presents a method to quantify the impact of a DG on protection system coordination by using two indices which are PMI and PMI ENS. PMI is used to evaluate the impact of size and installing location of a DG on protection miscoordination rate of the system, and PMI ENS is used to show the increase in energy not supplied of the system with a DG compared to the original system. In addition, maximum allowable capacity of a DG can also be determined using PMI and PMI ENS. For each system configuration, the indices were calculated from three-phase fault events by using Monte Carlo Simulation. Furthermore, to reduce the impact of a DG, protection coordination adjustment is also presented in this thesis. The proposed method has been tested with RBTS BUS 2 and a distribution system of Provincial Electricity Authority of Thailand. The obtained results clearly showed that both the size and the installing location of a DG had direct impacts on the protection coordination, and the proposed indices can be used to evaluate those impacts.