异步电机频率支撑能力分析及其等效惯量评估

Frequency support capacity of asynchronous motor andits equivalent inertia evaluation

与传统电力系统相比,新型电力系统正逐渐演变为直流和新能源高渗透的低惯量电力系统,负荷侧惯量占比逐渐升高。异步电机在负荷侧占比较高,须进一步研究其在惯性时间尺度下的频率支撑作用。为评估惯性时间尺度下异步电机的等效惯量,文中建立机械暂态下异步电机小信号模型,推导出其有关异步电机消耗功率和系统频率偏差的传递函数;同时文中推导出异步电机对电力系统的有效惯量并分析异步电机对电网呈现惯量的时变特性。根据惯量响应阶段频率具备支撑能力这一思路,分析异步电机惯量频率响应的影响因素,构建异步电机等效惯量评估模型,量化动态负荷的惯量频率支撑能力。最后在Matlab/Simulink和PSASP平台中搭建仿真模型,验证了所提评估模型和方法的正确性和有效性。

The new power system is gradually evolving into a low inertia power system with high penetration of DC and new energy,and the inertia of the load side is gradually increasing.Asynchronous motors occupy a high proportion in the load side,and their frequency support function needs further research.In order to evaluate the equivalent inertia of asynchronous motor under inertial time scale,a small signal model of asynchronous motor is established in electromechanical transient state.The transfer function of asynchronous motor power consumption and system frequency deviation is inferred in this paper.At the same time,the effective inertia of asynchronous motor to power system is inferred and the time-varying characteristics of asynchronous motor to power grid is analyzed.According to the idea of frequency support capability in inertia response stage,the factors which affect inertia frequency response of asynchronous motor are analyzed.The equivalent inertia evaluation model of asynchronous motor is proposed to quantify the frequency support capacity of dynamic load.Finally,a simulation model is built on Matlab/Simulink and PSASP platform to verify the correctness and effectiveness of the evaluation model and method proposed in this paper.