含分频风电的电力系统潮流计算方法以及稳态特性分析

对含分频风电的电力系统潮流计算方法以及稳态特性进行了分析.首先,给出了分频风电系统中的核心设备——交交变频器的潮流稳态模型.其次,根据上述模型,提出了一种利用统一迭代法计算含分频风电的电力系统潮流的新方法.该方法在传统的牛顿-拉夫逊潮流算法中增加了交交变频器模型,对雅可比矩阵进行了扩展.同时,分析了交交变频器控制参数对系统潮流的影响,并通过算例进行了验证.最后,针对2015年四川规划电网,利用潮流程序,对含分频风电的电力系统电压波动以及无功需求两个稳态指标进行了计算与分析.特别地,着重对低频侧采用变频率策略的分频系统与采用恒定频率策略的分频系统进行了比较.对典型日的分析表明,由于风电场主要运行在中低风速区域,因此采用变频率策略的分频系统的总体稳态指标会占优.

A Power Flow Calculation Method and Steady State Characteristics of Power System with Fractional Frequency Wind Power System

A power flow calculation method is proposed, and the steady state characteristics of the power system with fractional frequency wind power system (FFWPS) are analyzed. Firstly, the power flow model of cycloconverter is proposed. Then, a novel unified iterative method is introduced to calculate the power flow of a system with FFWPS. By this method, the admittances of transformers and transmission lines in lower frequency side are modified according to their operation frequency. Moreover, based on the model of cycloconverter, the Jacobi matrix is also extended. Finally, in the planning of power grid of Sichuan, the steady characteristics of the power system with FFWPS are analyzed, which includes the voltage fluctuation and reactive power demand. The steady characteristics of the FFWPS utilizing variable-frequency strategy are compared with that of FFWPS utilizing constant-frequency strategy. Analysis results for a typical day show that the aggregate indicators of the FFWPS utilizing variable-frequency strategy are better than that of constant-frequency strategy, because of the wind generators mainly operating at a low or medium wind speed.