基于PSCAD的大型机组失步保护仿真与整定校验

PSCAD-based setting calculation and simulation of out-of-step protection for large units

采用由一个透镜型阻抗元件和2个直线阻抗元件构成三元件型失步判据,给出了该判据的动作特性。说明了基于等面积原则的失步预测原理,进行了失步保护整定计算。采用PSCAD软件建立了单机容量为1 000 MW的三机无穷大系统的仿真模型、三元件型失步判据仿真模型和等面积预测失步的仿真模型。仿真结果表明,所提失步保护原理正确可靠,而且能精确地预测不稳定振荡并发出失步信号,通过滑极计数切除故障机组,且在稳定振荡时不误动。

A criterion composed of a lens-type and two straight-line-type impedance components is proposed for the out-of-step protection and its operational characteristic is given. The out-of-step prediction based on the equal area criterion is introduced and the setting calculation of out-of-step protection is carried out. The simulation models are built with PSCAD for the infinite system with three 1 000 MW machines,the three- component criterion and the out-of-step prediction based on equal area criterion. Simulative results show that,the principle proposed for the out-of-step protection is correct and reliable;the unstable oscillation is precisely predicted with the out-of-step signal and the faulty unit is tripped by counting the sliding pole number;and there is no misoperation during stable oscillation.