Real-Time Digital Simulation for a 50Mvar Cascaded Multilevel STATCOM

High switching frequency, complex and time-varying topology in high power electronics apparatus bring great difficulties to modeling and algorithm in real-time digital simulation. This paper presents a real-time digital simulator for a plusmn50 MVAr static compensator (STATCOM) using 21-level cascaded converter. The time-domain electromagnetic mathematical model of the 21-level cascaded STATCOM is proposed. To correct the inaccuracy caused by high frequency switching events and minimize the computational delay, the real-time digital simulation algorithm based on time average method is employed. The real-time digital simulator is implemented using digital signal processors (DSPs) and field programmable logic gates (FPGAs). Comparing with the simulation results using the offline simulator PSCAD/EMTDC, the real-time digital simulation results are verified. That shows the developed model and the algorithm are highly accurate. The developed real-time digital simulator has been used to test the actual controller of the plusmn50 MVAr STATCOM which ensures the successful commission.