Overcurrent protection adjustment when connecting synchronous generation to power supply systems

Abstract

The paper is devoted to the features of short-circuit current interruption under the conditions of small-scale distributed synchronous generation connection to medium voltage (MV) and low voltage (LV) power supply systems. Distributed generation (DG) even in a case of the unidirectional power supply has a great impact on overcurrent relay protection sensitivity and selectivity. Connecting DG leads to the specific character of short-circuit currents (SSC) of power supply systems, including increased level of short-circuit currents, current attenuation and the rate of aperiodic and periodic components. The paper also considers selection of setting values of specified time depending upon switchgear performance and the possibility of relay protection coordination for a generator and adjacent grid components.