在交直流混联电力系统中,直流再启动和直流闭锁会对交流联络线产生不同的冲击,从而影响电网的安全稳定运行。为此,分析了直流再启动和直流闭锁对交流联络线影响的数学机理和不同过程中影响交流联络线功率振荡的因素。结果表明:直流再启动时间越长引发的功率振荡越大,合理配置电力系统稳定器(PSS)可以有效抑制该类型振荡;直流闭锁时功率大范围转移造成的区域阻尼下降是导致交流联络线功率发散振荡的原因,切机与PSS配合对直流闭锁造成的功率振荡有良好的抑制效果;在直流重启动和闭锁的过程中,保证系统稳定的前提下,励磁调节器增益越大,交流联络线功率振荡衰减就越快;水流惯性时间常数对直流再启动造成的功率波动影响不明显,但直流闭锁后,较小的水流惯性时间常数易导致联络线功率等幅振荡。研究结果对于交直流混联系统的运行稳定性具有一定的参考价值。
In the AC-DC hybrid transmission grid, DC restarting and DC blocking will have different impacts on the AC tie-line, thus affecting the security and stability of the grid. We analyzed the mathematical mechanism of the influence caused by DC restarting and DC blocking and influencing factors of AC tie-line power oscillation. The results show that the greater power oscillations will be caused by the longer DC restarting time. Rational allocation of power system stabi- lizer (PSS) can effectively suppress this type of oscillation. The reason for the AC tie-line power diverging oscillation is the decrease of area-damping which is caused by power flow transfers when DC blocks. Cooperation of genera- tor-tripping and power system stabilizer has excellent control effect on oscillation caused by DC blocking. At the premise of power network stability, the attenuation processes of AC tie-line power oscillation become faster as the excitation reg- ulator gain increases, during the process of DC restarting and DC blocking. The water inertial time has no obvious influences on power oscillation caused by DC restarting, but persistent oscillation will be caused by smaller water inertial time when the DC blocks. The research results will provide references for the stable operation of AC-DC hybrid transmis- sion grid of the tie-line in AC-DC hybrid transmission grid during the process of by DC restarting and DC blocking.