基于综合制动判据的变压器差动保护研究

变压器差动保护的核心问题是如何鉴别励磁涌流与区内短路电流,防止保护误动作。该文针对传统二次谐波幅值比识别励磁涌流的方法存在判据单一、精确性不足、在某些情况下可能造成误动的问题进行改进,增加相位差判别的方法,并结合比率制动组建综合制动判据。利用MATLAB软件中Simulink实现模块的构建,对变压器在不同的运行情况下进行仿真校验。仿真结果表明:该判据不仅能够区分不同情况下的短路故障,而且能够有效地识别励磁涌流,并对变压器不同的故障类型作出相应的保护动作。

Transformer differential protection method based on the comprehensive braking criterion

The key problem of transformer differential protection method is the method to distinguish the inrush current from short circuit current in order to prevent mis-operation.The traditional method based on two harmonics amplitude ratios has a single criterion and insufficient accuracy,and thus it may cause a mis-operation in some conditions.On this background,the method of phase difference discrimination is improved,and the braking ratio is utilized to set up a comprehensive braking criterion.Simulation modules are modeled in Matlab/Simulink and the transformer is simulated and checked under different operating conditions.It is shown that the criterion not only distinguish short circuit faults in different situations,but also recognize inrush currents effectively,and make corresponding protection actions for different fault types of transformers.