含旋转电机接口和逆变器接口的微网小信号稳定性分析

提出了一种包含了逆变器接口（voltage source inverter，VSI）、同步电机接口（synchronous generator，SG）的独立微网控制策略，并分析了其小信号稳定性。VSI接口和SG接口的分布式电源均采用下垂控制策略，二者之间无需实时通信，可实现负荷功率共享。建立了系统的小信号状态空间模型，主要包括：同步发电机及其控制器的小信号模型、逆变器及其控制器的小信号模型、电网络及负荷小信号模型。计算了下垂增益变化时的根轨迹，得到了系统主特征值随参数变化的根轨迹，计算了不同状态变量对特征值的参与因子。稳定性分析结果表明：当所有分布式电源采用下垂控制时，引入同步发电机接口的分布式电源，系统频率小信号稳定性大大增强。PSCAD时域仿真验证了特征值计算的正确性。

Small-signal stability analysis of a micro-grid with a synchronous generator and an inverter-interfaced micro source

An independent microgrid control strategy including voltage source inverter (VSI) and synchronous generator(SG) was proposed, and its small signal stability was analyzed. Both VSI interfaces and SG interfaces used droop control strategy, sharing the load power without real-time communication. A small-signal micro-grid model was developed, including a small-signal model of the synchronous generator and its controller, a small-signal model of the inverter-interfaced micro source and its controller, and a small-signal model of the power network and its load. The eigenvalues were calculated when the droop gains change. The root locus of the principal eigenvalues were obtained when the main parameters change. And the participation factor of different state variables to the eigenvalues was investigated by PSCAD time domain simulations. The results show that the frequency stability is improved greatly by the synchronous generator when all micro sources use droop control. PSCAD time domain simulation verified the correctness of the eigenvalue calculation.