Linearity correction and control method of flow characteristics of thermal power unit desuperheating water control valve

Abstract

The invention discloses a linearity correction and control method for a flow characteristic of a temperature-reducing water regulating valve of a thermal power generating unit. A normal valve linearity correction method adopts a polygonal function but the method makes the valve have large fluctuation in a non-linear region. The technical scheme provided by the invention is as follows: the method comprises the step: after acquiring the flow characteristic of the temperature-reducing water regulating valve, the temperature-reducing water regulating valve adopts a valve fast opening adjustment mode, that is, when the valve is opened at an opening of 0-5%, the valve is quickly acted to a linear region of the flow characteristic of the temperature-reducing water regulating valve and is then regulated; and when the valve is closed to the non-linear region, the valve is automatically regulate to be closed. According to the method disclosed by the invention, a temperature-reducing control system of the thermal power generating unit is subjected to the minimum influence of the flow characteristic of the valve; the control quality of a steam temperature system is improved; the steam temperature control system can be in an automatic adjusting system when the unit is in a disturbing state (particularly in a start-stop process of a mill unit), so that the fluctuating extend is reduced, and the operating workload is greatly reduced.

Description

technical field [0001] The invention relates to the control of the temperature reduction control system of the thermal power unit, in particular to a linearity correction and control method for the flow characteristic of the thermal power unit desuperheating water regulating valve. Background technique [0002] The commonly used adjustment method for the desuperheating control system of large thermal power units is the desuperheating water control valve. When the flow characteristics of the desuperheating water control valve are poor, it often seriously affects the control quality of the steam temperature system, and sometimes even leads to the instability of the steam temperature system. It is an important reason for the overheating of the steam temperature system. In order to improve the control quality of the steam temperature system and ensure the safe and efficient operation of thermal power units, in addition to the excellent performance of the desuperheating control s...

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Problems solved by technology

[0003] In the steam temperature control of thermal power units, the mathematical model of the control object has the characteristics of large delay and large inertia. This mathematical model is fixed when the linearity of the valve flow characteristic is good, but when the linearity of the valve flow characteristic is poor, such as dead When the flow rate is low or leakage, the mathematical model is time-varying, which makes the design of the desuperheating control system more difficult. In addition to the multi-model caused by the change of working conditions, the change of valve characteristics also makes the object model of the desuperheating control system diversified. It is difficult to set the parameters of the valve. The commonly used valve linear correction method uses the broken line function, but this method will cause the valve to fluctuate greatly in the nonlinear region.

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