Large scale photovoltaic system and its impact on distribution network in transient cloud conditions

This paper presents simulation results from a real case study of a medium scale photovoltaic (PV) system integrated into an 11kV distribution network. The investigated system is a semi-rural part of an existing distribution network in Queensland, Australia with planned investments of more than 3MWp PV installation. The studied case is very interesting because of planned high penetration of PV power that exceeds the local peak load, even in high load conditions. In this paper, the authors are focusing on dynamic network conditions in the situation of a sudden drop in PV power production (shadow from clouds covering PV panels). It can result in a sudden drop of PV power generation and therefore significant voltage drops can occur. The investigated phenomena should be mitigated by control algorithms implemented within power system equipment such as On-Load Tap Changers (OLTC) and Series Voltage Regulators (SVR). The existence of significant time delays in control loops result in periods with grid voltage potentially without control.