考虑切换动态的功率同步控制单台构网型换流器暂态稳定性分析

This paper investigates the transient stability of the grid-forming converter with the power synchronization control (PSC) considering the switching dynamics. First, the mathematical model of the converter controlled by the PSC is established. Based on the switching dynamics theory, the system switching dynamic equations under the constant voltage control mode and the current limiting control mode are established, which transfers the conventional algebraic-variable switched model to the proposed state-variable switched model. Then, the transient stabilities in different control modes at the equilibrium points (EP) and the switching mechanisms are analyzed. It is interesting to find the “casual stable” switching property of the EP. That is, when the system suffers from large-signal disturbances, the system may return to a new stable point under the constant voltage mode or the current saturation mode. To ensure that the system is globally stabilized in the constant voltage mode under large-signal disturbances, a sufficient condition for stability is proposed. Based on this, two stability enhancement strategies by regulating the saturated current angle are proposed for the global stabilization and the maximum stability boundary of the first swing. Simulations are conducted to verify the effectiveness of the analytical derivations and the proposed controls.