线路两相短路故障电流控制的新方法

A novel control method for two-phase short current of lines

两相短路后,传统方法是切除故障线路,但这可能导致系统潮流大转移并可能引起系统不稳定,造成大面积停电事故。为此提出一种新型的故障电流控制器及与之对应的控制方法。故障电流控制器由串联变压器、并联变压器、2个可调电感以及有载调节开关构成,嵌入在线路的两端,工作时等效于电压源和电感的串联。两相故障后,改变与并联变压器原边相连开关的位置,将改变故障电流控制器等效电压源电压的相位,使故障相线路发送端(接受端)的电压源电压与超前(滞后)于故障相的电源电压同相,再协调控制2个可调电感,能独立控制其等效电压源电压的幅值和电感值,适当地控制这2个分量,能控制故障相间的线电流等于正常电流,该状态下线路的故障电流不仅为0,同时故障线路的电流也等于其正常运行时的电流,并在此基础上提出了两相短路故障电流的控制策略,建立了与之对应的控制系统。该方法能保持故障线路的继续运行,提高了线路供电的可靠性。实验证明了故障电流控制器能控制故障线路上的电流,使其等于正常运行电流,同时理论分析和仿真结果也证明了提出的故障电流控制器以及与之对应的两相短路电流的控制原理、控制策略的正确性。

The tremendous power flow may be transfered when two-phase short line is shut down, which may result in unstable state of the system and large loss of electric power. A novel line fault current controller （LFCC） and control method for the fault current of the two-phase short are presented. LFCC, emdedded at the line terminal, is composed of a series-connection transformer, a shunt-connection transformer,2 controllable induetors and on-line taps and is equivalent to the series of the insertion voltage and the insertion inductor when it works. The insertion voltage at the sending terminal（receiving terminal） is controlled to lead （lag）the fault source voltage by 2π/3 by adjusting on-line taps states. Because the insertion voltage amplitude and the insertion inductance can be controlled independently, the fault current gets zero and the current through the fault line reaches the normal current by the appropriate control of the insertion voltage amplitudes and the insertion inductances. Therefore, the fault line keeps the operation and the current through the line during the two-phase short existing equals that in normal operation, which improves the supply reliability. In addition, the corresponding control strategy for two phase short current is proposed. The experiment results show that the proposed LFCC is able to control the fault current through the line to reach corresponding normal current. The proposed control method suited for the proposed LFCC for the two phase short current is verified with the simulation results.