Testing Requirements and Control Strategies of Next-Generation Grid Emulator: A Review

The power-electronic-based grid emulator has been widely used for grid-code compliance testing of wind turbines (WTs). To accommodate the increasing voltage and power levels of WTs, the modular multilevel converter (MMC) emerges as a promising approach for the future grid emulator. This paper provides an overview of testing requirements and control strategies for the MMC-based grid emulator. Specifications, challenges and solutions to implement expected control functionalities of the MMC-based grid emulator are discussed according to testing requirements of WTs. Emerging testing functionalities and future trends of grid emulators conclude this paper.