面向变压器继电保护的励磁涌流分析及二次谐波制动保护

Analysis of Inrush Current and Second Harmonic Braking Protection for Transformer Relay Protection

为了提高电网系统的继电保护水平,分析了变压器继电保护中的励磁涌流现象,提出了更有效的二次谐波制动保护方法。在传统Jiles-Atherton模型(J-A模型)中引入涡流损耗和额外损耗,引入粒子群优化算法(PSO)智能识别特征参数,提出J-A改进模型。结合差动保护和二次谐波制动,采用J-A改进模型分析变压器磁滞过程并提取二次谐波。对比分析不同制动保护方法的实验结果,进一步探索J-A改进模型在不同温度下保护动作的有效性和可靠性。研究表明,二次谐波与基波的比值与温度呈正相关,温度越高,二者比值越低;而在二次谐波比方面,25℃、50℃时随时间增加而下降,75℃时随时间增加而上升。引入J-A改进模型能够自行调整二次谐波制动系数,有效防止励磁涌流误动,准确反应实际应用中的温度影响。该研究提高了电网系统的继电保护水平,有效避免了电网故障甚至系统崩溃等严重事故。

To improve the relay protection level of power grid system,this paper analyzed the inrush current phenomenon in transformer relay protection,and put forward a more effective second harmonic braking protection method.In the traditional Jiles-Atherton model(J-A model),eddy current loss and extra loss were introduced,and Particle Swarm Optimization(PSO)was introduced to intelligently identify characteristic parameters,and an improved J-A model was proposed.Combined with differential protection and second harmonic braking,J-A improved model was used to analyze the hysteresis process of transformer and extract the second harmonic.By comparing the experimental results of different braking protection methods,the effectiveness and reliability of J-A improved model at different temperatures were further explored.The research showed that the ratio of the second harmonic to the fundamental wave was positively correlated with the temperature,and the higher the temperature was,the lower the ratio was.As for the second harmonic ratio,it decreased with time at 25℃and 50℃,and increased with time at 75℃.The introduction of J-A improved model can adjust the second harmonic braking coefficient by itself,effectively prevent the maloperation of inrush current,and accurately reflect the temperature influence in practical application.This research improves the relay protection level of power grid system,and effectively avoids serious accidents such as power grid failures and even system crashes.