Design of a Grid-Forming Battery Energy Storage System for Voltage and Frequency Stabilization

Abstract

The fast development of renewable energy sources has resulted in a sharp decrease in the system inertia, which has raised serious demands in stabilising voltages and frequencies in contemporary power grids. The grid-forming (GFM) control of battery energy storage systems (BESS) has become an efficient approach used to increase the resilience of the system and allow it to operate in low-inertia environments. The presented paper introduces the design and analysis of grid-forming BESS to coordinate voltage and frequency stabilisation. A two-level scheme of hierarchical control is created and it contains an outer-loop voltagefrequency regulation system and an inner loop current control structure in the synchronous reference frame. The suggested approach allows independent grid support; such that results in consistent functioning during dynamic load changes, feeble grid conditions and fault perturbations. The overall mathematical model of BESS, battery dynamics, control of inverter, and the grid interaction, is developed. Stability is considered on the basis of small-scale analysis to test system robustness. The results of simulation work show that under extreme disturbances the proposed GFM-BESS minimises frequency deviation to 0.2 Hz and provides the regulation of voltage within a range of ±3 percent as compared to the traditional droop and the virtual synchronous machine (VSM) methods. Using the proposed system also leads to shorter settling time and reduced overall harmonic distortion which validates its applicability in the next generation resilient power system.