Power quality surveys of photovoltaic power plants: characterisation and analysis of grid-code requirements

In the past few years, grid-code requirements for grid-connected photovoltaic power plants have experienced a continuous evolution in different countries to ensure a reliable power system operation as the level of renewable energy penetration increases to high levels. According to several European grid-codes, PV power plants must be able to ride through specific and severe disturbances without disconnections. Under this new framework, the present study analyses intensive power quality surveys carried out from 2008 to 2011 in three different Spanish PV power plants: a fixed array installation with 4 MW PV power capacity, a PV power plant including dual axis-trackers with 1 MW PV power capacity, and one more fixed array PV power plant with 5 MW PV power capacity. Voltage dips and supply interruptions have been collected, discussing several methods to characterise the monitored disturbances and to compare these events to current Grid-Code requirements. Furthermore, the time interval around the residual voltage is proposed and defined by the authors as an additional parameter to provide a complete characterisation of the severity of the disturbances. Results from both characterisations of collected data and comparison with current requirements are also included in the study.