Centralized Synchronous Controller Based on Load Angle Regulation for Photovoltaic Power Plants

Abstract

The integration of renewable energies based on photovoltaic power plants (PVPPs) is increasing exponentially fast. In consequence, stability problems associated with the lack of inertia are becoming a serious concern. Transmission and distribution system operators are demanding more requirements in PV plants to provide grid functionalities in terms of frequency and voltage support. Therefore, power converters based on virtual synchronous controllers have been proposed to emulate the dynamic behavior of synchronous generators. Control strategies such as the synchronous power controller have been proposed for PV applications to fulfill this requirement. However, most of these control strategies are integrated locally as an add-on firmware embedded in each converter, providing the demanded support in their connection point. For PVPPs, the inherent synchronous characteristic is expected at the connection point with the electrical grid, which is not always the connection point of each power converter; thus, unexpected power support levels can be obtained. The aggregation of several power converters operating in a coordinated synchronous action would solve this issue, due to the fact that they can provide voltage and frequency support in a specific point. In this article, a centralized control strategy based on a synchronous central architecture is proposed. The control strategy emulates an aggregated synchronous control to regulate a PVPP as a coordinated system. The simulation and experimental results validate the effectiveness of the control proposed.