Steam temperature observation optimal control method for supercritical unit

Abstract

The invention discloses a steam temperature observation optimization control method of a supercritical unit. At present, most of the unit steam temperature control systems are too close to the desuperheating water valve, and the introduction of the pilot steam temperature cannot achieve the ideal control effect, and the effect of controlling the outlet steam temperature with a single-stage PID is even worse. The technical solution adopted in the present invention is: a state observation system is introduced into the outlet steam temperature control system to form an outlet steam temperature observation optimization control system. The state observation system uses a mathematical model to fit the dynamic process of the outlet steam temperature, and leads The signal and the leading observation signal are used for control, and the static difference elimination system is used to ensure that the outlet steam temperature observation optimization control system is stable without deviation; the mathematical model, state fitting, state feedback coefficient and control of the outlet steam temperature are determined according to the characteristics of the supercritical unit Feedback factor. The invention ensures the energy-saving operation of the unit; when the unit is in the AGC state, the fluctuation range of the main steam temperature is greatly reduced, 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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