A control strategy for unbalanced and nonlinear mixed loads of virtual synchronous generators

作者：Shi, Rongliang; Zhang, Xing; Liu, Fang; Xu, Haizhen; Hu, Chao; Yu, Yong; Ni, Hua

来源：Proceedings of the CSEE, 2016, 36(22): 6086-6095.

DOI：10.13334/j.0258-8013.pcsee.152442

• Distributed generation interface
• Harmonic voltages
• Stationary reference frames
• Unbalanced and nonlinear loads
• Unbalanced voltages
• Virtual impedance
• Virtual synchronous generator (VSG)
• Voltage unbalance and harmonics

Voltage source inverters based on virtual synchronous generator (VSG) control are usually used for all kinds of distributed generation interfaces in a microgrid, but the voltage and frequency of the microgird can be deteriorated under unbalanced and nonlinear mixed loads when the utility fails. A voltage unbalance and harmonics compensation strategy for the VSG in islanded microgrids was proposed. Firstly, the VSG equivalent impedance model was built to illustrate the effect of the output impedance on the system power quality in a two-phase stationary reference frame (αβ-SRF). Besides, a cascaded general-integrator (CGI) scheme was proposed to implement the virtual impedance to improve the compensation effect, which can avoid performing the time derivative function of output currents and increasing the dynamic response speed of the system significantly. Furthermore, the PI plus multi-resonant (PIR) voltage controller was used to compensate for the unbalanced and distorted output voltages of the VSG. Finally, the proposed strategy was demonstrated in detail and validated with a two 100-kVA VSGs parallel system under unbalanced and nonlinear loads.

• 出版日期2016
• 单位合肥工业大学