Frequency Shaping Control of Deloaded PV System Coordinated with Synchronous Generators

In a power system with growing proportion of photovoltaic (PV) generation and decreasing proportion of synchronous generators, the frequency regulation capability is becoming weak. To implement frequency control on PV, additional energy storage or power deloading is required, which brings additional cost to the PV station. Official technical standards and grid codes in a few countries and regions have specified the requirements for PV frequency control. Following the typical standard of frequency droop control, it is necessary to utilize the remaining PV power reserve to improve frequency characteristics such as frequency nadir and rate of change of frequency (RoCoF), and frequency shaping (FS) control is a promising solution for this task. With parameter tuning based on system model, frequency shaping control is implemented together with a fixed droop required by the grid code. The control strategy is tested with simulation, which shows frequency response with nadir eliminated and RoCoF improved. Moreover, a possible distributed and robust parameter tuning method for PV units in multi-machine system is discussed in the paper.