630 MW燃煤机组给水泵自动并泵过程控制策略

Control strategy for automatic parallel operation of feed water pumps in a 630 MW coal-fired unit

随着燃煤机组自启停控制的广泛应用,汽动给水泵(汽泵)并入的自动控制逐渐受到重视。本文对燃煤机组给水泵自动并泵控制策略进行优化,并在某电厂630 MW机组成功投运。运行结果表明:电动给水泵(电泵)运行时并入第1台汽泵的控制策略中,在被并入泵出口阀打开前后,设计2个升速阶段,将因汽泵转速变化而可能产生波动的参数设置为汽泵转速升速率函数的自变量,可使并泵过程非常平稳;全程耗时约4 min,给水流量波动在10 t/h以内;第1台汽泵运行时自动并入第2台汽泵的控制策略中,除给水主控PID外,额外引入2套PID功能块,分别用于2台汽泵出力自动调平,调平PID参数高度自适应,可使2台汽泵出力迅速调平而不引起主给水流量大幅度波动;全程耗时约7 min,给水流量波动在15 t/h以内。

As the wide application of automatic startup and shutdown control technology in coal-fired units, the control strategy of automatic parallel operation of steam driven pumps gradually draws much attentions. In this paper, the control strategy for automatic parallel operation of steam driven pump and electricity driven pump was optimized then applied in a 630 MW unit successfully. The results show that, in the control strategy the first steam driven pump participating in when the electricity driven pump is running, two rotating speed rising stages are designed before and after the outlet valve of the first steam driven pump is opened, the parameters that may fluctuate due to the change in the first team driven pump＇s rotating speed are set as the independent variables of the speed rising rate function of the steam driven pump, which makes the whole pump parallel operation process be very steady, the process takes 4 minutes for automatic parallel, with fluctuation of the feed water no more than 10t/h. In the control strategy the second steam driven pump participating in when the first steam driven pump is running, three PID functional blocks are applied in the control strategy of automatic parallel operation. One PID functional block is used for feedwater control and the other two that apply highly adaptive parameters are used to balance the contribution of two steam driven pumps, which shortens the time without leading to large fluctuation of feed water. It takes about 7 minutes for automatic parallel operation of a steam driven pump to another with fluctuation of feedwater less than 15 t/h.