基于降阶模型的多电源微电网小干扰分析

摘要

与传统大电网不同,微电网中电源种类较多,典型的微电源接口包括同步发电机、逆变器等,这使得微电网小干扰机电暂态分析时电网模型复杂,分析难度大。本文提出了含同步发电机和逆变器接口的微电网小干扰分析降阶模型,同步发电机采用三阶模型加一阶励磁控制器模型,逆变器忽略电流环、锁相环等快速动态过程,仅考虑功率环等慢动态过程。各个微电源接口首先在各自本地坐标轴上建模,然后通过网络方程将各微电源接口和负荷变换到统一旋转坐标轴,最后将方程线性化得到微电网小干扰分析模型。本文采用此模型分析了微电网孤网运行情况下网络参数变化和控制器参数变化对系统稳定性和动态性的影响,并采用PSCAD/EMTDC搭建仿真模型进行仿真研究,取得和特征值分析一致的结果,证明了这种建模方法的正确性。%Different from traditional power system,many kinds of micro sources are widely used in microgrid to connect distributed generation（DG） to grid,such as synchronous generator,inverter.As a result,the electrical mechanical transient model used in small signal analysis is very complex.This paper develops the modeling and analysis of autonomous operation of micro-grid with inverter and synchronous generator.A reduced order small signal analysis model is proposed.The synchronous generator adopts three order model and one order exciter model.The inverter considers the outer power loop.Each DG units is modeled in state-space form and all are combined together on a common reference frame.The complete model is linearized around an operating point and the resulting system matrix is used to derive the eigenvalues.The eigenvalue analysis was presented to identify the stability and dynamic effect when the controller and net parameters changes.The results are verified on the basis of the comparison with those obtained from time-domain simulation in the PSCAD/EMTDC environment.