Research on Optimization Control Strategy with PSS Based on VSG-Controlled Inverter

In a flexible DC transmission system utilizing a modular multilevel converter (MMC), the PQ control method falls short in providing the necessary inertia for the system. However, the conventional control approach for virtual synchronous generators (VSG) leads to active power oscillations, which adversely impact droop control. To tackle this problem, this paper proposes an enhanced control strategy for virtual synchronous generators (VSG) that utilizes power system stability (PSS) to effectively provide damping compensation. The active power deviation is utilized as the input of PSS, which outputs a value to compensate for damping power. This method improves the damping capacity, optimizes dynamic characteristics, and enhances system stability. This study examines the factors contributing to deviations in the power droop control of VSG. The PSS controller is incorporated into the active power control loop, with relevant parameters optimized. Then, a simulation model of a VSG-controlled MMC is developed in MATLAB, effectively validating the proposed method through simulations.