基于斯皮尔曼等级相关系数的新能源送出线路纵联保护

新能源电源均直接或间接通过电力电子装置并网,其故障电流幅值受限、相角受控、谐波含量高、波形非线性度强,与传统同步电源有着明显区别。传统比率制动式差动保护的动作性能面临挑战。为解决该问题,文中提出了基于斯皮尔曼等级相关系数的送出线路纵联保护方法。当正常运行或者区外故障时,流过送出线路的是穿越性电流,因此两侧电流波形完全相反。当发生区内故障时,两侧暂态电流波形存在巨大差异,因此可以利用斯皮尔曼等级相关系数量度两侧电流波形的相关程度,从而区分区内、区外故障。该方法适用于各类新能源场站,且具备较好的抗过渡电阻和抗噪声能力。同时,与现有基于新能源故障特征的保护相比,该方法在新能源弱出力以及重合于永久性故障时也表现出了较好的动作性能。仿真结果和现场录波数据均证实了该方法的有效性。

Pilot Protection Based on Spearman Rank Correlation Coefficient for Transmission Line Connected to Renewable Energy Source

Renewable energy sources are directly or indirectly connected to the grid through power electronic devices. Their fault currents have limited amplitudes, controlled angles, rich harmonics and strong nonlinearity, which are significantly different from that of conventional synchronous generators. The performance of conventional percentage restrained differential protection is facing challenges. In order to solve this problem, this paper proposes a pilot protection method based on Spearman rank correlation coefficient for transmission lines. When the system operates normally or an external fault occurs, a traversing current is flowing through the transmission line, so the current waveforms on both sides are completely opposite. When an internal fault occurs, there are huge differences between the transient current waveforms on both ends. Therefore, the Spearman rank correlation coefficient can be used to measure the correlation degree between the current waveforms on two ends, to distinguish the faults inside and outside the zone. The method is suitable for all kinds of renewable energy power plants, and has good performance on tolerating transition resistance and noise. Compared with the existing protection based on fault characteristics of renewable energy sources, the proposed method also shows good operation performance when the output power of renewable energy sources is weak and the breaker recloses into a permanent fault. Both simulation results and field recording data verify the effectiveness of the proposed method.