Virtual Synchronous Generator with Limited Current – Impact on System Transient Stability and Its Mitigation

Virtual synchronous generator (VSG) control allows renewable energy sources to behave like traditional synchronous generators under grid disturbances. Under large disturbances, due to the limitation of output current from grid interfacing power electronic converters, VSG controlled sources may output less active power than the emulated SG. Analysis of a single machine infinite bus system shows that the limited current would impair the system transient stability by increasing the acceleration area during a short circuit fault, and decreasing the deceleration area after it. A mitigation method is then proposed to compensate the negative impacts. Experiments with an emulated downscaled multiple machine system are shown to demonstrate the feasibility of the proposed method.