小水电并网系统电压稳定分岔研究

对一个小水电并入负荷中心的简化系统详细推导出常微分状态方程组，在此基础上运用MATCONT软件进行了以有功负荷为单参数的分岔计算，结果显示平衡点曲线上先后出现Hopf分岔点和鞍结分岔点，对系统电压稳定性造成了潜在威胁；运用双参数分岔分析方法研究了水轮机输入机械转矩Mm和励磁系统AVR增益KE对电压稳定性的影响，可知增大Mm能有效延迟鞍结分岔，也可在一定程度上延迟Hopf分岔；而增大KE只能在一定程度上延迟鞍结分岔，对Hopf分岔基本无影响。研究结果表明在丰水期小水电满发有利于提高系统的电压稳定性。

Research on the Voltage Stability Bifurcation of the Grid-connected Small Hydropower System

The ordinary differential equations(ODEs) was derived in detail for a simplified power system which contains a small hydropower in load center, and one-parameter bifurcation analysis was conducted by MATCONT based the ODEs, taking the active power of load as bifurcation parameter. The The ordinary differential equations(ODEs) was derived in detail for a simplified power system which contains a small hydropower in load center, and one-parameter bifurcation analysis was conducted by MATCONT based the ODEs, taking the active power of load as bifurcation parameter. The bifurcation calculation results show that a Hopf bifurcation(HB) point and a saddle-node bifurcation(SNB) point occur successively in the equilibrium point curve that can engender potential harm to voltage stability. This paper used the double-parameter bifurcation analysis method to study the influence of mechanical input Mm of hydraulic turbine and the AVR gain to voltage stability, the results show the increasing of the Mm can delay the SNB effectively and the HB to a certain extent, and the increasing of the KE can only delay the SNB finitely and has no influence to the HB. The conclusion can be obtained that full capacity operation of small hydropowers are beneficial to voltage stability in high water season.