含分频风电的电力系统机电暂态计算方法以及暂态特性分析

Electromechanical Transient Calculation Method and Transient Characteristics Analysis of Power System with Fractional Frequency Wind Power System

对含分频风电的电力系统机电暂态计算方法以及暂态特性进行了分析。首先,建立了交交变频器的准稳态模型,该模型反映了暂态过程中变频器两侧的电压、功率关系。其次,提出了含分频风电的电力系统暂态稳定算法。该算法将交交变频器准稳态模型与低频、工频两侧的网络方程相连得到系统网络代数方程。同时,利用交替迭代法对系统微分—代数方程组进行求解。最后,对含分频风电的电力系统的暂态稳定特性进行了分析。分析结果表明,由于低频侧电抗仅为工频系统1/3左右,故障时低频风力发电机转速响应的阻尼高于同距离的工频系统。同时,当低频侧故障时交交变频器对工频侧发电机的振荡具有明显的抑制作用。

The electromechanical transient characteristics of a power system with fractional frequency wind power system （FFWPS） are analyzed. Firstly, a quasi-steady state model of the cycloconverter is established, which describes the relationship of voltages, active power and reactive power between the two sides of the cycloconverter during the transient process. Secondly, the calculation method is proposed to analyze the transient stability of the power system with FFWPS. This method combines the quasi-state equations of the cycloconverter and the network equations on both sides. Then these simultaneous equations are solved with the alternating iterative method. Thirdly, the transient stability of the power with FFWPS is analyzed, the results show that the damping of the rotating speed of a faulted wind generator in the fractional frequency system is bigger than that in the industrial frequency system. Moreover, when a fault occurs at the low frequency side, the eycloconverter can effectively restrain the oscillation of the generators at the industrial frequency system.