Improved control strategies for three-phase four-leg virtual synchronous generator with unbalanced loads

This paper proposes improved multi-loop control strategies for three-phase four-leg virtual synchronous generator with unbalanced loads. Through the decoupling control of active and reactive power, inverter can simulate the characteristics of synchronous generator, including primary frequency modulation, primary voltage modulation, inertia and excitation characteristics. To improve the dynamic performance of micro-grid, the voltage and current dual-loop is cascaded after the power loop. In addition, to solve the problem of unbalanced voltage and frequency fluctuation in VSG caused by unbalanced load, a variable frequency adaptive resonance control strategy is proposed. The simulation and experiments validate the effectiveness of the proposed control strategy.