A novel methodology for dynamic voltage support with adaptive schemes in photovoltaic generators

The levels of renewable power, particularly from photovoltaic power plants (PVPPs), injected into different electrical systems bring with them a series of fundamental technical changes that need to be addressed. Power quality (PQ) and voltage stability are the ones of great concern. In this sense, voltage sags commonly affect many users. For this reason, the need to implement dynamic voltage support or fault ride through (FRT) schemes and to inject reactive current into PV generators is evident taking into account the experience of network operators. However, this strategy presents important limitations to comply with the additional requirements established in the IEEE 1547 standard. The standard establishes the need in the continuity of the PV inverter contribution opposite successive voltage sags, delay in voltage recovery and island operation, among others. Therefore, any FRT strategy must consider these additional aspects in order to effectively mitigate voltage events. In the present work, a novel methodology for dynamic grid support based on adaptive FRT schemes is described. The proposed dynamic control will be the result of a detailed voltage support strategy. The methodology implemented will consider all the fault conditions that can lead to the occurrence of voltage sags and similar events. The results of those tests carried out for a PV generator linked to the IEEE 33 buses system show that the implemented strategy operates according to the requirements of current standards for different voltage events.