Enhanced Lyapunov-Based Control for Inverter Systems in Series-Compensated Transmission Networks

Abstract

Series capacitor compensation is widely employed in transmission lines to compensate for grid impedance and enhance the transmission capability of renewable power. However, it can adversely affect inverter current control and potentially induce system oscillations. In conventional linear control theory, lead compensation can be applied to increase the phase margin and address the instability issues. Nevertheless, the compensation typically requires multiple rounds of offline adjustments and relies heavily on accurate system modeling and precise calculation of compensation frequencies, making it difficult to achieve online optimization control. In recent years, advanced control strategies, such as those based on the Lyapunov function, have been significantly developed. However, existing control strategies cannot be directly applied to inverter systems with series compensation, as they do not account for the effects of grid impedance and series capacitors. To bridge this gap, this article proposes a current control scheme based on the Lyapunov direct method to mitigate the impact of series compensation on current control stability. A Lyapunov function that ensures global stability is derived and implemented. The perturbation gains are designed using root locus analysis to improve both static and dynamic performance. Finally, the effectiveness of the proposed control strategy is validated through experiments.