配电网PT铁磁谐振的机理分析

Ferro-resonance principle analysis for distributed system

利用相模变换理论,建立配电网发生绝缘放电时的故障分析模型,运用时变相量的分析方法分析配电网PT发生铁磁谐振的原因,并建立非线性并联铁磁谐振模型,分析电网发生铁磁谐振的机理.配电网的铁磁谐振分为两种类型,即暂态谐振和稳态谐振,发生暂态谐振的主要原因是由于扰动发生时,电网对地等效电容被迅速充电,导致电容储存的电能对PT放电导致暂态谐振.稳态谐振的发生机理则是由于PT铁磁非线性导致系统存在多个稳定运行点,当扰动较大时,将使得配电网电压运行点从正常的状态转移到谐振的稳定运行状态,能否激发稳态谐振取决于扰动量的大小.利用胜利油田6 kV系统作为仿真对象,仿真结果表明,上述理论是正确的,对解决配电网PT烧毁事故具有指导意义.

A fault analysis model is established for insulation discharging distribution network with Phase-mode transform theory.The reason of PT resonance is introduced with time-various phasor theorem and a nonlinear parallel ferro-resonance mode is founded.And the mechanism of ferro-resonance is analyzed.The phenomena of ferro-resonance can be classified into two categories,the transient and steady resonance.The transient resonance is caused by the electric charge stored in the capacitance discharge to the PTs.The reason to the steady resonance is that there exists more than two steady state points,once the oscillation is larger enough,the operation state could be moved to the resonance state.ATP simulation results associated with the 6 kV oil field power system show that the principle is correct,and can be applied to avoid the PT destroying by resonance phenomena.