Steam temperature observation optimal control method for supercritical unit

Abstract

The invention discloses a steam temperature observation optimal control method for a supercritical unit. At present, as a point measuring position is excessively near a desuperheating water valve in steam temperature control systems of most of units, an ideal control effect cannot be achieved on introduced advancing steam temperature, and the effect of controlling outlet steam temperature is poorer by using single-stage proportion integration differentiation (PID). The technical scheme adopted by the invention is that a state observation system is introduced into an outlet steam temperature control system to form an outlet steam temperature observation optimal control system. The dynamic procedure of the outlet steam temperature is fit by the state observation system by adopting a mathematical model, and the control is performed through an analog advancing signal and an advancing observation signal. Meanwhile, the steady state and the zero deflection of the outlet steam temperature observation optimal control system are ensured by adopting a static error eliminating system. The mathematical model, the state fitting, the state feedback factor and the control feedback factor of the outlet steam temperature are determined according to the characteristic of the supercritical unit. According to the steam temperature observation optimal control method for the supercritical unit, energy-saving operation of the unit is ensured; the fluctuation range of the outlet steam temperature is greatly reduced when the unit is in an automatic gain control (AGC) state; and the stability of the unit is enhanced.

Description

technical field [0001] The invention relates to the steam temperature control of a thermal power generating set, in particular to a supercritical steam temperature observation optimization control method. Background technique [0002] The steam temperature control system of a supercritical unit has the characteristics of nonlinearity, large delay, and many disturbance factors. Generally, peak-shaving units often have severe fluctuations in steam temperature, and changes in fuel volume (that is, coal volume) and air volume have significant impacts on the main steam temperature control system. Larger disturbances, in order to ensure the safe and economical operation of the steam turbine, under the specified load, a higher requirement is put forward for the temperature of the superheated steam, that is, it must be controlled within the range of +5°C to -10°C of the rated value. It is difficult to control the main steam temperature control system in the above temperature range. ...

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Problems solved by technology

[0002] The steam temperature control system of a supercritical unit has the characteristics of nonlinearity, large delay, and many disturbance factors. Generally, peak-shaving units often have severe fluctuations in steam temperature, and changes in fuel volume (that is, coal volume) and air volume have significant impacts on the main steam temperature control system. Larger disturbances, in order to ensure the safe and economical operation of the steam turbine, under the specified load, a higher requirement is put forward for the temperature of the superheated steam, that is, it must be controlled within the range of +5°C to -10°C of the rated value. It is difficult to control the main steam temperature control system in the above temperature range

In the steam temperature control of thermal power units, the steam temperature control system of some units is overly sensitive to the leading steam temperature. Most of the steam temperature control systems of the units are due to the poor installation of the measuring point, which is too close to the desuperheating water valve. Therefore, in the conventional In the cascade control system, the introduction of the leading steam temperature cannot obtain the ideal control effect, and the effect of controlling the outlet steam temperature with a single-stage PID is even worse.

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