逆变器VSG小信号建模与参数设计

Small Signal Modeling and Parameter Design for VSG of the Inverter

虚拟同步发电机(VSG)技术能为并网逆变器提供类似于同步发电机的惯性特征,是分布式发电和微电网领域的核心技术之一。针对VSG控制器的建模和参数选取问题,对VSG功率回路进行了小信号建模,分析得知功率回路带宽需远小于线频的2倍,以避免VSG输出电压严重失真。在此基础上推导了VSG的线频平均小信号模型,可用于参数设计。同时,在线频平均小信号模型基础上给出了有功和无功功率控制解耦的条件。最后,利用10 kV·A并网逆变器原理样机进行了试验研究,研究结果验证了理论分析和参数设计方法的有效性。

Virtual synchronous generator(VSG)technology provides inertial characteristics similar to synchronous generators for grid-connected inverters,and it is one of the key technologies in the field of distributed generation and microgrids. Aiming at the modeling and parameter selection problem of the VSG controller,the small signal modeling of the VSG power loop was carried out. The power loop bandwidth was analyzed to be much less than twice the line frequency to avoid severe distortion of the VSG output voltage. Based on this,the line-frequency average small-signal model of VSG was derived and could be used for parameter design. At the same time,based on the line-frequency-averaged small-signal model,the conditions for the decoupling of active power and reactive power controller was given. At last,the experimental research on the 10 kV·A grid-connected inverter prototype was carried out. The results verify the validity of the theoretical analysis and parameter design method.