Fossil power plant coordination control method based on multi-parameter prediction

Abstract

The invention discloses a fossil power plant coordination control method based on multi-parameter prediction. Aiming at the characteristics that a boiler controlled object is lagged, slow in response process and the like, feedwater flow, coal supply quantity and steam turbine valve opening are estimated reasonably, deviation of main steam pressure and separator outlet temperature is predicted, and a main steam pressure control loop and a separator outlet temperature control loop are respectively formed, and are coordinated with a load control loop so as to form a fossil power plant coordination control system. Control quality of the fossil power plant coordination control system is effectively improved, main steam pressure fluctuation during load change is suppressed effectively while the load change is responded fast, deviation between main steam pressure and a setting value is reduced, the separator outlet temperature fluctuation is suppressed, and the situation that the separator outlet temperature is over high is reduced. Besides, the stability of a boiler control system and the operation efficiency of a unit are improved.

Description

technical field [0001] The invention is a control strategy based on the combination of model predictive control and multi-parameter prediction, which can adjust the main steam pressure of the thermal power unit boiler and the outlet temperature of the separator, so that the main steam pressure and the outlet temperature of the separator can be quickly, stably and without deviation. A method of control that tracks a set point. Background technique [0002] At present, the coordinated control strategy of domestic thermal power units mainly adopts the configuration logic provided by major foreign manufacturers, and adopts the adjustment scheme of load command feedforward and proportional integral differential feedback. The core idea is to set the entire control system as much as possible. In the open-loop regulation mode, the feedback regulation only plays a small regulation role. This scheme requires that the parameters of the feedforward control loop must be set very accurat...

AI Technical Summary

Problems solved by technology

[0003] 1. The ability to eliminate disturbance is poor, and it is prone to large fluctuations in parameters and adjustment oscillations

[0004] This is the most common situation in the operation of the unit at present. When the unit is under disturbance conditions such as large load changes, starting and stopping of the pulverizing system, and soot blowing, the control system often has unstable control or a large deviation of the temperature and pressure from the set value. situation, which seriously affects the safety of operation

[0005] 2. The load lifting rate of the unit is low

[0006] Conventional AGC control scheme, because it is impossible to find an effective control method for the controlled object with a large lag, the rate of increase and decrease of the unit load is only about 1% / min, and the capacity of the unit’s peak regulation and frequency regulation is poor, which cannot meet the power grid’s load on the unit. Response request for

[0007] 3. The change of coal type has a great influence on the control system

In order to ensure the safety of the unit, the operators can only operate at a very low variable load rate

[0009] 4. Large fluctuations in control quantities of fuel and water supply

[0010] The frequent and repeated changes of the load command make the unit’s fuel, water supply, air supply and other control quantities fluctuate greatly. At this time, although the controlled parameters such as the main steam pressure and temperature are relatively stable, it will cause the water wall of the boiler and the superheater tube to be damaged. Repeated changes in thermal stress can easily lead to the peeling off of scale, which greatly increases the possibility of boiler tube burst

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