A Coordinated PV-Battery GFM Control for Power Management and Frequency Support

Grid-forming (GFM) control becomes an emerging technology due to its advantages like frequency and inertial support, being a promising solution for the large-scale integration of renewable energy like solar photovoltaic (PV). In order to solve the fluctuation of the PV system (PVS) and reserve extra energy for frequency support, a battery energy storage system (BESS) is usually adopted. However, the PV-BESS needs collaborative control to manage the energy and support the grid flexibly. In this paper, a coordinated GFM strategy is developed for the PV-BESS to provide frequency support and achieve a better energy management. The coordinated PV-BESS GFM control allows the BESS to absorb power from the grid and participate in the regulation of the grid frequency. The coordinated PV-BESS GFM strategy has been validated by simulations in MATLAB and experimental tests on a lab-scale PV-BESS.

I. Introduction

In recent years, the widespread adoption of renewable energy sources (RESs), such as photovoltaic (PV), has been driven by their environmentally-friendly characteristics [1]. To resolve the issues brought by the large-scale adoption of power electronics-based RESs, various strategies have been developed. Among those, grid-forming (GFM) control becomes an emerging technology thanks to its strong frequency and inertia support capability [2], [3]. The grid-forming (GFM) inverter can be equated to a controlled voltage source, capable of controlling the output voltage amplitude and phase angle [4], [5]. The GFM control mainly simulates the synchronous generator electromechanical characteristics through the power synchronization control loop. Through the GFM control, the power of the GFM increases “autonomously”, when the grid fault angle changes, providing instantaneous inertia support [6], [7]. GFM inverters can regulate harmonics by adjusting the virtual impedance and realize 100% renewable energy grid integration. The typical GFM control at present includes the droop control [8], virtual synchronous generator (VSG) control [9], and virtual oscillator control (VOC) [10].