微电网孤网运行时的频率特性分析

Analysis on Frequency Characteristics of Islanded Microgrid

微电网孤网运行时的频率特性是微电网运行机理分析和控制策略研究的基础。针对逆变器、同步发电机和异步发电机不同接口型微电源,分别从控制策略、传递函数和结构特点等方面进行定性和定量分析,结果表明不同的微电源具有差调频、无差调频和无调频特性3种不同的调频作用。微电网的频率特性由不同微电源的调频特性共同决定,是否存在无差调频型微电源是影响微电网孤网频率特性的关键。基于PSCAD仿真平台,针对2个简单微电网和1个复杂微电网分别进行仿真计算和定性、定量分析,仿真结果验证了微电网孤网频率特性理论分析的正确性,并得到不同微电源组合情况下的功率分配特性。

The frequency characteristics of islanded microgrids are the basis for the feature analysis of microgrid,which is very important for the coordinated control of the microsources.Different power-frequency characteristics of the microsources are analyzed theoretically on the basis of the control algorithm,the transfer function and the structural features,which have different interfaces with the microgrid,such as inverters,synchronous generators and asynchronous generators.The analysis results show that different microsources have different frequency regulation functions,including the droop regulation function,the zero error regulation function and no frequency regulation function.The frequency characteristics of the microgrid are determined by the power-frequency characteristics of different microsources.The existence of zero error regulation function of microsources is a key for the frequency characteristics of the microgrid.The frequency characteristics of two simple microgrids and a complicated microgrid with different microsource combinations are simulated using PSCAD.The simulation results coincide with the theoretical analysis results,which verify the validity and effectiveness of the above conclusions.At the same time,the power distribution feature is derived for different microsource combinations.