TOV for renewable, evaluating three different grounding technologies

Temporary overvoltages (TOV) are oscillatory overvoltages mainly caused by switching or faults, which are of relatively long duration and undamped or slightly damped. Maximum overvoltages under faulted conditions can require considerable energy magnitudes absorbed by surge arresters. These energies may overpass maximum limits and lead to equipment damage. This project presented a study to identify the maximum TOV at the MV equipment of a PV power plant during fault-clearing events. Two methods of TOV suppression are evaluated, including grounding transformers and fast grounding switches under two different configuraions. An electrical model was elaborated in EMTP to perform the simulation of the transient overvoltage due to the un-balanced fault clearance, considering each inverter of the PV plant. The results show that considering no grounding technologies at the feeders, the energy absorption limit is overpassed in the islanded system. Therefore, a fast grounding switch or a system with grounding technology at each feeder is needed in order to protect the substation equipment.