风火打捆外送系统暂态稳定切机控制

Generator Tripping Control to Uphold Transient Stability of Power Grid Outwards Transmitting Thermal-Generated Power Bundled With Wind Power

风火打捆能源基地的投入运行,在带来巨大经济效益的同时也引起电网安全稳定性发生变化。某些严重故障后,仅切除常规火电机组难以保证系统稳定运行或代价过大。首先分析了风电机组和火电机组暂态特性的差异性以及各自对系统暂态稳定的影响。然后指出了严重故障后导致系统失稳的2个主要原因:一是故障过程中产生了加速能量;二是由于故障后,外送通道被削弱,外送系统输电能力急剧下降。因此,提出了严重故障后火电机组和风电机组的优化切机方案。西北某电网的仿真结果表明:该优化切机方案在保证故障后系统安全稳定运行的基础上,能显著降低系统稳定恢复所需切机量,改善故障后系统恢复特性,大大提高系统运行的安全性和经济性。

The putting into operation of energy base,where wind power is bundled with thermal-generated power,can bring great economic benefits,meanwhile it will also leads to the variation of both security and stability in the power grid located in the energy base.It is hard to ensure stable operation of the power grid by only tripping conventional thermal generation units after certain serious faults or the cost of tripping conventional thermal generation units is too high.In allusion to it,firstly,the difference between the transient characteristics of thermal generation units and that of wind power generation units as well as the impacts of the two kinds of transient characteristics on system transient stability are analyzed;secondly,it is pointed out that there are two main reasons causing post-fault system instability： one of them is the accelerating energy produced during fault process and the another one is the sharp decline of the capability of outward power transmission system due to the weakening of outward power transmission channel;thirdly,an optimal scheme for tripping thermal units and wind power units after the serious faults is proposed.Simulation results of a certain energy base in West China,where the thermal-generated power is bundled with wind power,show that under the premise of ensuring post-fault secure and stable operation of the power grid,using the proposed optimal generator tripping scheme the quantity of generators to be tripped can be evidently reduced and the restoration characteristics of post-fault power grid can be improved,thus both security and economy of the power grid can be obviously enhanced.