双馈风力发电机三相短路分析及短路器最大电阻整定

Three-phase short-circuit analysis for double-fed wind-driven generator and short-circuiter maximal resistance calculation

双馈风力发电机三相短路保护装置的整定取决于其短路电流。为了提高整定精度,提出将三相短路过程分解为稳态运行和反向电压暂态运行2个部分,并建立了相应的数学模型。利用Maple软件对数学模型进行拉普拉斯变换及其逆变换,求取短路电流的解析表达式,并用仿真方法加以验证。分析结果表明在短路电流中存在直流分量、交流基波分量和交流谐波分量,各分量的变化规律由双馈风力发电机的参数、转差率及转子励磁电压决定,而短路电流的大小主要取决于交流分量。因此,根据短路电流的交流分量对短路保护装置最大电阻进行了整定。

The three-phase short-circuit protective device of double-fed wind-driven generator （DFIG） is set according to its short-circuit current. An approach is proposed to increase the setting precision, which decomposes the three-phase short-circuit process into the steady movement and the reverse voltage transient movement. The corresponding mathematical model is established. Laplace transformation and its inverse transformation are performed with the Maple software on the model to deduce the analytic expression of short-circuit current, which is verified by simulation. The analytic result indicates that, there is DC compo- nent,AC fundamental and AC harmonics in the current, influenced by the DFIG parameters, slip and rotor excitation voltage, and the magnitude of short-circuit current mainly depends on the AC components. Therefore,the maximal resistance of short-circuit protective device is set according to the AC components.