Method for automatically adjusting steam feed pump near critical point of opening recirculation valve

The invention discloses a method for automatically adjusting steam feed pumps near a critical point for opening recirculation valves, which comprises the following steps of: when the critical point at which the recirculation valves of two steam feed pumps are simultaneously opened is reached, setting a rotating speed offset for one of the steam feed pumps, so that the inlet flow of the corresponding steam pump is slowly increased; and far away from the critical point for opening the corresponding recirculation valve, only the other steam feed pump slowly opens the corresponding recirculation valve. According to the method for automatically adjusting the steam feed pump near the critical point of opening the recirculation valve, the single recirculation valve is opened, so that in the unit load change process of an ultra-supercritical coal-fired unit, when the critical point of the recirculation valve is opened, the main feed water flow fluctuation is not too large; the device is particularly suitable for the