特高压直流换相失败对送端电网风机暂态无功特性的影响分析

Influence of UHV DC Commutation Failure on the Transient Reactive Power Characteristics of Wind Turbines in Sending Terminal Grid

特高压直流输电是风力发电远距离输送的有效方式,得到了大量的研究和实际应用。换相失败故障作为常见的直流输电故障,导致风电大规模接入的送端电网中产生了电压幅值非阶跃变化、先低穿后高穿的电压故障特性。为了分析换相失败故障下送端电网特性,需要准确获得换相失败故障下风电系统的暂态无功响应特性。该文针对直驱风电系统和双馈风电系统,将电网故障下风电系统暂态响应分解为故障发生前稳态、电网电压变化状态、变流器输出电压变化状态等3个状态分别建模,得到了考虑不同电网电压故障状态和变流器控制参数等因素的风电系统无功响应模型,仿真结果对数学模型正确性进行了验证。此外,根据换相失败故障下送端电网电压波形,利用所建立数学模型分析了风电系统控制参数对输出无功特性的影响规律。

The ultra high voltage direct current(UHVDC)transmission is an effective way for long-distance transmission of wind power,has obtained a lot of research and practical applications.The commutation failure fault is a common DC transmission fault,which results in a voltage fault characteristic in which the voltage amplitude non-step,first sag and then swell in the sending terminal of large-scale access of wind power.In order to analyze the characteristics of the sending terminal grid under the fault of the commutation failure,it is necessary to accurately obtain the transient reactive characteristics of the wind power generation system under the fault of the commutation failure.In this paper,for the directly-driven wind power generation system and the doubly-fed wind power generation system,the transient response of the wind power system under the grid fault was decomposed into three states:the steady state before the fault occurs,the grid voltage change state,and the converter output voltage change state.The reactive power response model of wind power generation system considering factors such as different grid voltage fault states and converter control parameters was obtained.The simulation results verify the correctness of the mathematical model.In addition,according to the measured waveform of the grid voltage of the sending terminal under the failure of commutation,the mathematical model was used to analyze the influence of the control parameters of the wind power generation system on the output reactive power.