An Advanced Average-Value Model of Full-Bridge MMC Station with Blocking Capability

The average-value model (AVM) of MMC can greatly shorten the simulation time on the basis of simulating the dynamic characteristics equivalent to the detailed full bridge MMC (FB-MMC) model. However, the AVM cannot simulate the blocking state correctly under the abnormal working state. Therefore, a blocking average-value model (BAVM) of FB-MMC considering the effect of anti-parallel diodes is proposed to simulate the blocking characteristics. Four thyristors are connected to the equivalent circuit used to simulate the full bridge portion. In normal state, the thyristors are bypassed, and BAVM performs the same characteristics as AVM. In the blocking state, the thyristors are turned on by additional control strategies to charge the SM capacitor to correctly simulate the role of the diode in the detailed model. Based on the benchmark system established in $\mathbf{PSCAD}/$ EMTDC, the BAVM of FB-MMC is compared with the detailed switching model. The simulation result shows that the BAVM can accurately simulate the blocking characteristics, and has the same performance as the detailed full bridge MMC model, and the simulation time is greatly reduced.