Three-Phase Four-Wire Inverter for Grid Emulator under Wide Filter Inductance Variation

This paper proposes a new three-phase, four-wire grid emulator to simulate possible grid scenarios such as frequency and amplitude fluctuations and high harmonics. When using conventional PI and DDC, there is a phase difference between input and output response. Therefore, a modified DDC (MDDC) is adopted which can track the harmonic voltages precisely. The MDDC is dicussed in detail and the results are verified by simulations and real tests.