光伏组件的雷电感应过电压和过电流计算

Calculation of Voltage and Current Induced by Lightning Electromagnetic Fields in Photovoltaic Modules

随着太阳能在我国能源比例中的持续增长,对光伏发电系统可靠性的要求变得越来越高。因此,光伏组件防雷保护已经成为一个非常重要的课题。介绍了光伏发电系统设备的雷击损害机理,计算不同防雷方式下光伏组件回路的感应过电压。建立光伏组件等效电路模型,分析旁路二极管上承受的雷电过电流。计算表明:雷电流波头陡度越大,光伏组件距离雷击点越近,感应过电压幅值越大。光伏电池单元和旁路二极管反向安装时,旁路二极管上承受的雷电过电流幅值和过电流持续时间要小于正向安装方式。雷电过电流极易损坏旁路二极管,需要安装诸如瞬态抑制二极管之类的浪涌防护装置,减小回路线缆面积。

Reliability requirements of photovoltaic （PV） systems become more important as the share of solar energy in our country energy balance continues to grow. Mechanisms of lightning damage to PV system equipments are presented concretely. Induced voltages in different protection ways in the PV module loop are also calculated. The equivalent circuits of PV module are established to calculate induced circuit currents. The results show that overvoltage in the loop increases with increasing of gradient of lightning current as well as distance between PV modules and lightning strike point. Magnitude and duration of induced current in bypass diode are smaller when bypass diodes are placed in reverse direction than in forward direction. Bypass diodes are vulnerable to lightning induced current and it is necessary to install surge protection devices such as transient voltage suppressor （TVS） and decrease the area of the loop.