一种基于变步长差分的电压暂降检测方法

电压暂降的实时、准确检测是快速补偿的前提,但频率偏移下基于软件锁相环的检测方法无法准确地检测出相位跳变角。基于αβdq变换,提出利用变步长差分来构造出电压的αβ分量,采用恒定50Hz单位正、余弦信号瞬时采样值来构成αβdq 变换阵,从而计算出电压幅值与相位跳变角,避免了锁相保持给相位跳变角带来的测量误差。并就谐波、噪声及频率偏移等影响因素,对改进方法进行了详细的检测特性分析。理论分析和仿真结果表明,基于变步长差分的改进检测方法,实现方式简单且计算量小,无需同步锁相,可通过调节检测点间隔满足实时性与精确度的不同要求。

A Voltage Sag Detection Method Based on Variable Step Difference

The quick and accurate detection of voltage sag is the premise of fast compensation, but under the condition of frequency offset, the phase jump angle is hard to be detected precisely by the software phase locked loop. Based on αβ-dq transform, a detection method by utilizing variable-step difference is proposed to generate αβ components of voltage in this paper. By using instantaneous sample values of the constant 50Hz sine and cosine signals to form αβ-dq transform matrix, Voltage amplitude and phase jump angle can be calculated, which avoids the measurement error in phase jump angle caused by phase lock holding. The detecting characteristics for such influence factors as harmonics, noise and frequency offset are analyzed in detail by using modified methods. Theoretical analysis and simulation results show that the improved method based on variable\|step difference has such advantages as easy realization mode and less calculation amount, which can meet the requirement of real-time and accuracy by regulating detecting sample interval without needing of synchronous phase clocking.