一种基于复阻抗的电压暂降定位方法

A voltage sag detection method based on complex impedance

电压暂降是目前电力系统最重要的电能质量问题之一,日益受到社会的关注。针对传统算法运算复杂、精度较差的缺陷,提出了一种基于复阻抗的电压暂降定位方法。该方法首先对检测到的电压和电流信号分别进行Hilbert变换构造其解析信号,然后计算对应的复阻抗,利用电压暂降发生时阻抗和相位突变的特性,结合超限判别,准确定位电压暂降的发生时刻,检测出其持续时间,最后通过实验验证所提方法的有效性。实验结果表明,该方法检测精度高、易于判别,具有广泛的推广价值。

Voltage sag is currently one of the most important power quality problems in power system, which has become increasingly a focus of attention in society. Due to the defects of traditional algorithm that has complex operation and poor precision, this paper proposes a voltage sag detection method based on complex impedance. Firstly, Hilbert transform is used to construct the analytic signals for detected voltage and current signals separately, and then their corresponding complex impedance will be calculated, making use of the specialty that when the voltage sag happened, its impedance and phase angle will jump at the same time, and combining overrun discriminator, the proposed method can locate the occurrence time of voltage sag, and detect its time duration. Finally, the effectiveness of the proposed method in this paper is verified by several experiments, the experimental results show that this method has high accuracy and easy to distinguish, it has wide promotional value.