考虑变压器励磁非线性的电磁暂态仿真算法

An Approach for Electromagnetic Transient Simulation of Power Transformers With Nonlinear Exciting Branch

建立了一种含有非线性励磁支路的变压器电磁暂态仿真模型。通过简单的仿真线路,仿真了变压器空载合闸时发生励磁涌流的现象。应用分段线性化的方法处理变压器励磁支路的非线性问题,并通过不同仿真步长下励磁电流的仿真结果,说明了分段线性化在大步长下出现的过冲现象。减小仿真步长可有效抑制过冲,但是仿真时间明显增加。在分段线性化方法的基础上提出了预测校正法改善过冲问题。在变压器电磁暂态仿真的程序设计中加入了预测校正模块,在不改变步长的情况下,解决了过冲问题,加快了仿真的计算速度。最后通过仿真结果验证了变压器模型及预测校正方法的正确性和有效性。

A model for electromagnetic transient simulation of power transformer containing nonlinear exciting branch is built and the inrush current of power transformer under no-load switching is simulated by a simple simulation circuit. Applying piece-wise linearization the nonlinear phenomenon appeared in exciting branch of power transformer is processed and by means of simulation results under various simulation step lengths the overshoot appeared due to long step length adopted in piece-wise linearization is explained. The overshoot can be effectively limited by decreasing the step length, however the time for the simulation is evidently increased. On the basis of piece-wise linearization a predictor-corrector method is proposed to ameliorate the overshoot. A predictor-corrector module is added into the electromagnetic transient simulation program for power transformer, thus without changing step length the overshoot is overcome and the simulation process is accelerated. Simulation results verify the correctness and effectiveness of the proposed transformer model and the predictor-corrector method.