光伏直流系统对地绝缘检测方法研究

Research on DC System to Ground Insulation Detection Method for Photovoltaic Power Stations

光伏直流系统对地绝缘故障将会对设备运行和人员安全造成严重影响,对直流系统绝缘性能进行在线检测是防止事故发生的有效途径。对常用的直流系统对地绝缘检测方法进行研究分析,结合光伏电站直流系统的特点,提出一种电桥检测法与差流检测法相结合的、适用于光伏直流系统的对地绝缘检测方法。实验表明,该方法能够准确检测直流母线对地绝缘阻值的大小,并消除了电桥检测法中存在的共模电压波动问题,提高了直流系统的安全性和稳定性。

The DC system to ground insulation fault of the photovohaic power station may cause serious impacts on the safe operation of equipment and personnel safety. The online monitoring of the DC system insulation is an effective way to prevent accidents. This paper studies the common detection methods used for the DC system to ground insulation, and based on the characteristics of the DC system of the photovoltaie power station, the paper proposes a new insulation detection method which combines the bridge method and differential current method and is suitable to the DC system to ground insulation detection for photovoltaic power stations. The experimental results shows that the method can accurately delect the insulation resistance of the DC bus, and eliminate the common mode voltage fluctuation produced by the bridge method, and improve the security and stability of the DC system.