Numerical relay protection coordination using simulation software

The paper presents protection coordination of renewable energy source connected to bilaterally supplied distribution network. Multifunctional numerical relays with the switching equipment, renewable energy source facility and the distribution network have been detail modeled in DIgSILENT Power Factory software. Overcurrent, overvoltage, undervoltage, directional overcurrent, underfrequency and overfrequenecy functions have been used for protection coordination. Different relay characteristics have been presented in one time-overcurrent plot. The damage curve and characteristic currents of electrical equipment in the network have been shown to set the relay tripping times and current settings and for a good and thorough protection of the equipment. Protection coordination settings have been checked and verified simulating faults with the real system values.