Comparison between inverters based on virtual synchronous generator and droop control

Abstract

Droop control is generally used to realize power sharing without communication lines. VSG (Virtual Synchronous Generator) is a control method that mimics both steady-state droop and dynamic characteristic of SG (Synchronous Generator) to enhance inertia of microgrid. In this paper, the comparison of different damping effect forms in VSG control is given firstly to draw conclusions: For the aspect of mimicking the damping effect of real SG physical models, it is better to use one form of damping effect term in the VSG active power control loop. For the aspect of improving the system frequency stability, it is better to use another form of damping effect term in the VSG active power control loop. Then a comprehensive comparison of VSG and droop control is presented to support the conclusion: no matter what kind of damping effect, the VSG control can always be regarded as a special case of droop control with a specific compensator parameter design, which mimics rotor inertia and damping effect of SGs. However, fully mimicking the performance of SG is not the optimal strategy in different situations. The compensator parameters of droop control can be designed according to the system requirements to adapt different situations. Simulations and experimental results are provided to support the conclusions.