光伏发电系统并网点谐波电压波动特征孤岛检测法

An islanding detection method for photovoltaic power generation system using fluctuation characteristic of point of common coupling harmonic voltage

光伏发电系统并网点处的谐波电压由系统扰动、本地负荷和光伏发电系统共同确定,基于波动量法提出一种以并网点谐波电压波动量为特征的光伏发电系统孤岛检测方法。测量公共联结点谐波电压,用小波变换法提取测量电压中包含的高次谐波分量,以高次谐波电压波动量变化规律作为孤岛识别和检测指标,无需外加扰动,可消除检测盲区。基于IEEE.Std 1547标准,对理想光伏发电并网系统进行的仿真证明,利用并网点测量电压中包含的谐波电压波动量进行孤岛检测,当测量点处的电压和频率在正常范围内时,不仅可快速、准确地检测孤岛,还能准确识别电网故障引起的电压暂降、投切负荷等干扰,避免伪孤岛引起的检测错误。

In the photovoltaic power generation systeml the harmonic voltage of the point of common coupling （PCC） is determined by system disturbance, local load and photovoltaic power generation system itself together. Based on the fluctuations of this harmonic voltage, a new islanding detection method for the PV system is proposed. By extracting the higher harmonic components from the wavelet transformation of point of common coupling （PCC） voltage, and then taking its fluctuations as the islanding identification and detection index, non-detection zone （NDZ） can be eliminated, without a plus disturbance. According to IEEE Std. 1547, simulated verification of the proposed method is accomplished in the ideal photovoltaic grid system. When the PCC voltage and frequency are within the normal range, it can not only give a fast and accurate detection to the occurrence of islanding, but also identify the false islanding, such as voltage dips and switching loads, effectively avoiding false detection caused by the false islanding.