FPGA-Based Real-Time Simulation of Modular Multilevel Converter HVDC Systems

摘要

AC-HVDC-AC energy conversion systems using MMC (modular multilevel converters) are becoming popular to integrate distributed energy systems to the main grid. Such multilevel converters pose a serious problems for HIL (hardware in the loop) simulators required for control, protection design and testing due to the large number of cells that must be simulated individually using very small time steps. This paper demonstrates the advantages of using a very small time step to simulate a MMC topology. The MMC is implemented on FPGA (fiel-programmable gate array) to simulate fast transient with a time step of 250 ns. The AC network and HVDC bus is simulated on the PC, with a slower time step of 10 us to 20 us. The simulator architecture and the components simulated on the FPGA and on the PC will be discussed, as well as the method allowing the interconnection of this slow and fast system.