Design and Implementation of a Multi-Loop Control Scheme for Three-Phase Grid Emulator Including Neutral

Grid emulators are used to test grid connected equipments under normal and diverse disturbed grid conditions according to standards and local grid codes. This paper presents a multi-loop control scheme with proportional and resonant controller for a three-phase four-leg voltage source converter working as grid emulator. The methodology of designing all controllers involved in the control scheme is proposed. The stability and the general performances of the grid emulator are discussed through simulation and experimentation using a dSPACE 1006 rapid-prototyping system. The obtained results demonstrate the emulator's capability to accurately track the reference voltage with a fast transient response and thus, emulate normal and faulty grid behavior.