Control method of minimum-flow recirculation valve of water supply pump of power station boiler

Abstract

The invention discloses a control method of a minimum-flow recirculation valve of a water supply pump of a power station boiler. The control method comprises the following steps: collecting real-time rotation rate (or outlet pressure) and actual water inlet flow of the water supply pump in real time; determining the minimum flow according to a corresponding relationship between minimum flow in a safe running area of the water supply pump and the rotation rate (or outlet pressure) of the water supply pump, real-time rotation rate (or outlet pressure) and positive value offset; comparing the minimum flow with the actual water inlet flow to obtain flow deviation signals; feeding the flow deviation signals into a hysteresis curve function and processing to obtain a control output instruction; carrying out first-order inertial element LAG calculation processing on the control output instruction with different time constants in uplink and downlink directions to obtain a valve opening control instruction; carrying out function processing on the control output instruction to obtain a control quantity; by taking the valve opening control instruction and a large value in the control quantity as output signals, controlling the valve opening of the recirculation valve of the water supply pump. The control method can be used for quickly responding and stably and reliably controlling the recirculation valve of the water supply pump.

Description

technical field [0001] The invention relates to the fields of thermal power engineering and automatic control, in particular to a method for controlling a minimum flow rate recirculation valve of a power plant boiler feed water pump. Background technique [0002] The boiler feed water pump is an important auxiliary machine of a thermal power plant, which has a great influence on the safe and economical operation of the power plant. In order to ensure the normal operation of the feed water pump without cavitation, it must be satisfied that the effective NPSH of the pump cannot be lower than the necessary NPSH under any working conditions. Both the effective NPSH and the necessary NPSH are related to the flow of the pump. When the effective NPSH of the pump is equal to the required NPSH, the corresponding pump flow is called the minimum flow of the feed water pump. In order to protect the safety of the feed water pump and prevent the feed water pump from working below its min...

AI Technical Summary

Problems solved by technology

[0007] Based on this, the purpose of the present invention is to provide a method for controlling the minimum flow recirculation valve of the power plant boiler feed water pump, which can realize fast response, stable and reliable control of the recirculation valve of the feed water pump, and solve frequent and unstable adjustment of the recirculation valve, valve core Internal leakage caused by flushing, uneconomical problems caused by premature opening under low load conditions

Images