基于模型的变压器保护判据分析与改进

对基于模型的变压器保护原理作了分析并提出了新判据。电流暂态波形波动较大时,用差分代替微分会造成很大误差,可能造成保护误动。利用积分法构成了新型的保护判据,给出了新判据的计算公式并讨论了定值的选取。变压器在正常运行、外部故障、空载合闸、内部故障、带内部故障空载合闸等工况下的数字仿真结果表明,新判据不易受电压、电流波形波动的影响,计算简单,可以可靠、快速识别变压器内部故障。

Analysis and improvement of transformer protection criterion based on model

The transformer protection principle based on transformer model is analyzed and the new criterion is provided.When current transient wave fluctuates obviously,the use of difference instead of differential may cause prodigious error and malfunction.The new-type protection criterion is composed of integral.Its calculation formula is presented and the selection of its settings is discussed.Digital simulation results under conditions of normal operation,external fault,no-load closing,internal fault,no-load closing with internal fault and so on show that,the new-type criterion is not sensitive to voltage and current fluctuation,easy to calculate and fast to identify transformer internal fault.