Sliding-pressure operation unit optimizing control method in automatic gain control (AGC) mode

Abstract

The invention relates to a sliding-pressure operation unit optimizing control method in an automatic gain control (AGC) mode, and the method has the advantages of simplicity, effective reduction of oscillation occurrence, economic efficiency of unit operation and the like. The method comprises the following steps: 1) filtering load setting after load is set; 2) setting an ideal sliding-pressure curve according to the best efficiency points of throttling and circulating efficiencies; 3) realizing automatic optimizing of sliding-pressure setting by utilizing a pure integral module of proportion integration differentiation (PID); 4) increasing a high-low limit module after a pressure setting velocity is limited so as to prevent a pressure setting value from exceeding the range permitted by unit safety operation; and 5) manually setting the load setting by operators when the AGC is not carried out, wherein the load is prevented from small oscillation, corresponding pressure setting is prevented from small oscillation, and pressure setting in logics is switched to an operation bypass.

Description

[0001] technical field [0002] The invention relates to an optimal control method in an AGC mode of a sliding pressure operating unit. Background technique [0003] The basic basis of sliding pressure lies in two factors: under low-load conditions, one is to limit the steam flow into the steam turbine through high valve throttling, resulting in throttling loss and increasing coal consumption; the other is that reducing the main steam pressure can Reduce the throttling degree of the high-profile valve, but the reduction of the main steam pressure causes the cycle efficiency to decrease. According to the characteristics of the Rankine cycle, the higher the main steam parameter, the higher the cycle efficiency, and vice versa. Therefore, the direction of steam turbine development is to improve the main steam parameters, and subcritical, supercritical, and ultra-supercritical units have been produced. In the sliding pressure operation mode, to reduce the main steam parameters...

AI Technical Summary

Problems solved by technology

[0006] Secondly, the unit operating under sliding pressure can meet the economical efficiency of the unit when the AGC command moves in one direction and greatly moves, but when the AGC command fluctuates slightly, the economical efficiency of the unit is obviously affected

This is because when the AGC command oscillates slightly, the pressure setting value of the unit in sliding pressure operation will also oscillate slightly in the sliding pressure section. In order to meet the requirements of AGC, the current units generally set There are differential links of pressure and load setting values ​​to improve the response rate to AGC. The existence of a large number of differential links will inevitably lead to the unit’s coal volume fluctuating when the AGC command and pressure setting values ​​fluctuate slightly. Water, steam temperature and other systems will also oscillate accordingly

Coal fluctuations will inevitably increase the coal consumption of the unit and affect the economy of the unit

In addition, when the pressure of the supercritical unit changes, the heat storage of the unit changes very obviously, which will affect the stability of the outlet temperature of the separator, and further affect the stability of the unit pressure, thus having a great impact on the AGC adjustment quality of the unit

[0007] Finally, when the AGC command fluctuates slightly for the unit operating under sliding pressure, the economy generated by the sliding pressure cannot make up for the increased coal consumption caused by the fluctuation of coal volume. In addition, due to the hysteresis existing on the boiler side, the unit pressure and pressure setting cannot be guaranteed. exact match of value

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