集中式光伏并网输电线路的故障暂态分析与保护

集中式光伏并网输电线路发生故障时，光伏侧的故障暂态过程与系统侧完全不同，导致传统工频量保护动作性能下降。为提高保护动作的可靠性，分析了集中式光伏并网输电线路光伏侧短路电流的故障特征，推导了光伏侧短路电流三个不同阶段的近似解析表达式，并详细分析其功率控制暂态过程的变化特征。发现光伏侧的暂态电流为非旋转量，与系统侧衰减旋转量的波形特征截然不同。基于此特性，提出了一种基于暂态电流波形相关性的纵联保护方法。仿真结果表明所提保护方案在各种故障类型和不同的过渡电阻下均能可靠动作，有望提高光伏并网输电线路的安全运行能力。

Fault Transient Analysis and Protection for Transmission Lines with Integration of Centralized Photovoltaic

When the transmission line with integration of centralized photovoltaic(PV)fails, the fault transient process on PV side is completely different from system side, which leads to a decrease in the performance of the conventional relays based on power frequency. In order to improve the reliability of protection action, the fault characteristics of short-circuit current on PV side for transmission lines with integration of centralized PV are analyzed and then the approximate analytical expressions of short-circuit current on PV side in three different stages are deduced. The variation characteristics of power control transient process are analyzed in detail. It is found that the transient current on PV side is a non-rotational amount, which is completely different from the waveform characteristics of the attenuation rotating amount on system side. Based on the characteristics, a novel polit protection method based on the waveform correlation of transient current is proposed. Finally, the simulation results show that the proposed protection scheme could operate reliably with various fault types and different transition resistances, which is expected to improve the safe operation capability of transmission lines with integration of centralized PV.