Main steam pressure control system with intelligent static deviation elimination function

Abstract

The invention discloses a main steam pressure control system with an intelligent static deviation elimination function. A pressure deviation delta p is compared with a set minimum limit P1 and a set maximum limit P2, when the difference is greater than a rated value, a pressure deviation delta p intelligent elimination loop starts timing, and the timing length t is increased progressively along with the fact that delta p exceeds high and low limit time; and when the intelligent elimination loop for the pressure deviation delta p is input, t is reset and re-timed, and when the pressure deviation cannot be corrected in one period, the loop continuously acts until the deviation is eliminated. When PID control integral adjustment and differential adjustment reach balance and main steam pressure static deviation exists for a long time, the scheme can be used for effectively eliminating the main steam pressure static deviation, when a unit has small pressure deviation and PID integral deviation correction is not obvious, the scheme can be used for rapidly and intelligently eliminating the main steam pressure static deviation, and the situation that the steam temperature deviation is too large due to the fact that the fuel amount is increased or decreased too violently is avoided. The commissioning and retreating conditions, time and amplitude are controllable, frequent fluctuation of fuel quantity can be reduced, and the service life of equipment is prolonged.

Description

technical field [0001] The invention relates to the technical field of eliminating static deviation of main steam pressure of a thermal power unit, in particular to a main steam pressure control system with intelligent elimination of static deviation. Background technique [0002] The main steam pressure is a main parameter of boiler combustion control. If the pressure is too high, the stress of each pressure-bearing component will increase, the risk of equipment damage will increase, and the steam humidity of the blades of the last stages of the steam turbine will increase, which will affect the life of the blades; if the pressure is too low, the unit will be economical. The performance cannot be guaranteed. In order to maintain the load, the steam flow rate needs to be increased, the axial displacement of the steam turbine unit increases, and the possibility of dynamic and static rubbing increases. Very frequently, the unit puts forward stricter requirements on the main st...

AI Technical Summary

Problems solved by technology

Therefore, it is necessary to adopt a larger differential gain to predict the change trend of the pressure deviation in advance, and a larger differential gain will often suppress the integral component, resulting in the static deviation of the main steam pressure cannot be eliminated

[0005] 2: In the original control loop, when the main steam pressure deviation △p is small, the integral effect is not obvious, and the deviation correction time is longer

[0006] 3: The original control loop uses PID to calculate the amount of fuel. To eliminate △p in a short period of time, it is necessary to enlarge the control parameters, which will easily cause unstable steam temperature.

[0007] 4: The original control loop controls the amount of coal reduction frequently, and there is no precise exit logic, resulting in frequent addition and subtraction of fuel and reducing the life of the equipment

[0008] 5: In the original control loop, if the integral control component is increased, it is easy to cause the main steam pressure to fluctuate back and forth, affecting the adjustment performance of the unit under static load

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