基于低电压穿越去磁控制的风电场内部故障等值建模方法

风电场内部故障引起的区域性、多风电场连锁脱网事故会对电网造成严重影响。文中基于低电压穿越(LVRT)去磁控制,以故障后Crowbar投切为机群划分依据进行风电场等值。首先,考虑转子侧控制器的影响,并且在不忽略转子电流的情况下,通过状态方程计算故障后、Crowbar投入前这段时间的定子磁链。然后,结合去磁控制的投切判据,计算转子所需去磁电流,从而判断Crowbar是否投切,并以此对风电场机组进行分群。分析风电场内部故障特点,不改变集电网络结构与参数,通过非线性规划确定等值机组接入集电网络的位置。算例与仿真结果表明,所提方法能够准确反映故障前后的风电场特性。

Equivalent Modeling Method for Wind Farm Inner Fault Based on Demagnetizing Control of Low Voltage Ride Through

The regional and multiple wind farm cascading trip-off induced by the wind farm inner fault will cause serious impacts on the power grid. Based on the demagnetizing control of low voltage ride through(LVRT), wind farm equivalent modeling is carried out according to the generator groups divided by the switching criterion of Crowbar circuit after the fault. First, by taking the influence of rotor side converter into consideration, and with the rotor current not ignored, the stator flux during the period between the moments the fault occurs and Crowbar circuit switches in is calculated through the state equation. The demagnetizing rotor current is then obtained by combining with the switching criterion of demagnetizing control strategy. Thereby the generators of the wind farm are divided by estimating whether the Crowbar is to act or not. After analyzing the characteristics of wind farm inner fault, the original collector network need not be changed, but the access points of equivalent generators are determined by using nonlinear programming. Finally, example and simulation show that the method proposed can accurately reflect the characteristics of the wind farm before and after the fault.This work is supported by State Grid Corporation of China(No. SGSDDK00KJJS1500155).