A Real-Time Hybrid Modular Multilevel Converters Emulator for Hardware-in-Loop-Tests

Abstract

Real-time simulation of modular multilevel converter (MMC) is essential for delivering practical projects. However, existing real-time MMC simulators have functional limitations in some aspects. To solve this problem, this paper presents a general-purpose MMC emulator with a hybrid submodule topology. The MMC emulator is implemented on the field-programmable gate array (FPGA), supporting all circuit parameters flexible configuration and internal fault real-time simulation with a time-step of 2 μs. Each submodule has its own independent storage space for configurability. To improve the accuracy of the simulation, all equations are calculated in the single floating-point precision. This paper adopts a novel method based on partial results caching and merging unit, which can reduce the latency of the accumulation. Moreover, a fault parameter addressing module is presented to simulate internal MMC valve faults. The real-time simulation results, which are obtained by simulating YUE Back-to-Back Project, are provided to verify the correctness of the designed emulator.