Adaptive Grid Forming Control of STATCOM to Improve DC Dynamics in Hybrid AC-DC Microgrid

Abstract

A grid-forming static synchronous compensator (STATCOM) is a power electronic device that regulates voltage, provides active and reactive power support, and stabilizes power systems by mimicking the dynamic behavior of traditional synchronous machines. When integrated with an energy storage system (ESS) from a DC microgrid, it ensures efficient power exchange and enhances system resilience to disturbances. By maintaining the DC-link voltage and synchronizing with the AC grid, a grid-forming STATCOM plays a pivotal role in stabilizing both AC and DC subsystems. However, challenges such as dynamic AC grid impedance variations, transient power fluctuations, and the poor adaptability of conventional controllers can lead to voltage instability and oscillatory behavior, particularly in weak grid conditions. This paper presents a novel adaptive control strategy for a grid-forming STATCOM that dynamically adjusts control parameters in response to real-time AC grid impedance measurements obtained through a broadband perturbation technique. By adaptively tuning the damping coefficient in the virtual synchronous machine (VSM) framework, the proposed method ensures robust voltage regulation, mitigates oscillations, and improves transient performance at the DC-link. Experimental results validate the effectiveness of the proposed approach, highlighting its capability to achieve stable operation under varying grid conditions and enhancing the reliability of DC microgrids.