计及频率特性的感应电动机参数变化对负荷特性的影响

对于网架结构比较薄弱的省网系统或者系统解列后形成的孤岛,发生故障时会引起比较大的频率波动。感应电动机作为电力系统动态负荷的主要成分,进行建模时考虑其频率特性尤为重要。基于感应电动机数学模型,考虑恒机械转矩、恒机械功率和变机械转矩等不同负载特性,在计及频率特性的情况下,通过解析法得到感应电动机转子滑差、有功功率和无功功率的表达式。当感应电动机的定子电感、转子电感、励磁电感和转子电阻变化幅度分别为±30%时,分析负荷特性参数变化对不同频率下的感应电动机吸收有功功率和无功功率的影响。利用Matlab建立感应电动机五阶电磁暂态仿真模型,仿真分析感应电动机参数变化对负荷特性的影响。将理论计算与仿真实验的结果进行对比,验证了所提方法的正确性。

Influence of induction motor parameter change considering frequency characteristics on load characteristics

When a network system with a weak network structure or an island formed after a system is decomposed, a relatively large frequency fluctuation may occur. As the main component of the dynamic load of the power system, it is particularly important to consider the frequency characteristics when modeling an induction motor. Based on the mathematical model of induction motor, this paper considers different load characteristics such as constant mechanical torque, constant mechanical power and variable mechanical torque. Taking into account the frequency change, the expressions of rotor slip, active power and reactive power of the induction motor are obtained by analytical method. When the induction motor''s stator inductance, rotor inductance, magnetizing inductance and rotor resistance change amplitude are ±30% respectively, the influence of load characteristic parameter changes on the active power and reactive power absorbed by induction motor at different frequencies is analyzed. Using Matlab to establish the fifth-order electromagnetic transient simulation model of induction motor, the influence of induction motor parameter changes on load characteristics is simulated and analyzed. Comparing theoretical calculation results with simulation experiment results, the accuracy and effectiveness of the proposed method are verified. This work is supported by National Natural Science Foundation of China (No. 51367009).