基于Frechet距离的零模涌流识别及过流保护闭锁策略

Zero-Mode Inrush Current Identification and Zero-sequence Overcurrent Protection Blocking Strategy Based on Frechet Distance Algorithm

变压器空载合闸时会产生零模涌流,涌流幅值高且持续时间较长,可能会引起零序过流保护的误动作,这一现象在高阻抗变压器(HIT)大量投运的场合更为严重,需要为其配备合适的闭锁方案.针对该问题,设计了一种基于Frechet距离算法的零模涌流识别及保护闭锁判据,并利用Frechet距离满足三角不等式、波形分析多元化等优势,通过计算零模涌流波形相邻周期的Frechet距离值并设定阈值来识别零模涌流,弥补了在空载合闸情况下二次谐波制动等方法不能有效识别零模涌流的问题.仿真结果表明,该判据可以有效识别出零模涌流,且具有较强的抗干扰能力.

When the transformer is closed at no load,the zero-mode inrush current will be generated,and the inrush amplitude is high and lasts for a long time,which may cause the malfunction of the zero-sequence overcurrent protection,which is more serious in the case of a large number of high-impedance transformers(HIT),and it needs to be equipped with a suitable locking scheme.Given this,this paper designs a zero-mode inrush current identification and protection lock-up criterion based on the Frechet distance algorithm,and uses the advantages of Frechet distance to satisfy trigonometric inequality and waveform analysis diversification,and identifies the zero-mode inrush current by calculating the Frechet distance value of the adjacent period of the zero-mode inrush waveform and setting the threshold,which makes up for the problem that the methods such as second-harmonic braking cannot effectively identify the zero-mode inrush current in the case of no-load closing.The simulation results show that the proposed criterion can effectively identify the zero-mode inrush current and has strong anti-interference ability.