Research on AC Microgrid With Current-Limiting Ability Using Power-State Equation and Improved Lyapunov-Function Method

With the occurrence of the major blackouts in “Australia 9·28” and the “U.K. 8·9,” the technical bottlenecks in the power generation system with a high proportion of renewable energy have attracted more and more attention. Based on this background, this article studies a control method that is suitable for AC microgrid with strong current-limiting ability. First, the outer loop controller adopts the method of power-state equation based on PI control to achieve accurate tracking of the reference power. Furthermore, in order to make the fault current having a lower asymmetry degree and smaller amplitude, the outer loop controller only considers the positive-sequence components of the voltage and adds twice rated current limiter. Second, the inner loop controller adopts an improved Lyapunov-function method with antiparametric disturbance ability to track the reference inductance current. By selecting the optimal controller gains, the current harmonics and amplitudes can meet the desired requirements. Finally, the simulation builds a microgrid with four distributed generators (DGs) in MATLAB/Simulink and tests the effectiveness of the proposed current-limiting method.