Primary steam temperature adjusting method and adjusting system

Abstract

The invention relates to a thermal power station primary steam temperature control system and control method thereof. The system according to the method comprises a primary PID controller and a secondary PID controller. The method is characterized by comprising the following steps that (1) a preset value is inputted to the primary PID controller; and (2) a primary steam temperature measured value is compared with the primary PID controller preset value, and the secondary PID controller takes the output value of the primary PID controller as the preset value when the deviation is within the range of the set value. According to the primary steam temperature adjusting method, the preset value of the primary PID controller is set, and segmented control and adjustment are performed on the difference value of the primary steam temperature measured value and the primary PID controller preset value so that the quality of primary steam temperature control and adjustment can be greatly enhanced, the whole process of primary steam temperature automatic adjustment under the unvarying condition can be truly realized, and the excellent adjustment quality can be maintained in the automatic adjustment process.

Description

technical field [0001] The invention relates to a thermal power station main steam temperature control system and a control method thereof. Background technique [0002] The main steam temperature is one of the main control parameters of the thermal power unit, and its control effect directly affects the safe and economical operation capability of the unit. At present, the main steam temperature control system of thermal power units generally adopts the traditional PID cascade control. Although this control scheme is easy to debug on site, it cannot adapt to the characteristics of variable parameters, large inertia, and large time delay of the main steam temperature control system, which leads to the main The steam temperature automatic control system generally has a good automatic control quality when the load is stable, but in the process of load changes, start / stop coal mills, etc., the main steam temperature fluctuates greatly, and even the automatic cannot be put into o...

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Problems solved by technology

[0005] At present, although there are many advanced control technologies for main steam temperature, such as prediction technology, fuzzy technology, neural network technology, etc., the above-mentioned technologies are more theoretical, with many academic articles, mainly simulation verification, and poor engineering field applicability. Although there are on-site application examples, they are highly specific to individual cases and poor in popularization and promotion, which is not conducive to on-site commissioning of projects

[0006] After in-depth research on the principle of main steam temperature control, it was found that the root of the problem was that the temperature behind the secondary desuperheater was increased or decreased due to the increase or decrease of the water spray volume, which caused the temperature to change drastically, resulting in control disorder. PID control parameters to improve the quality of the main steam temperature regulation is powerless

[0007] The current common PID-based control scheme is cascade regulation, but there are fatal problems in the control process:

[0008] 1) When the main steam temperature is higher than the set value, sometimes the cascade control system will gradually close the valve, so that the main steam temperature will not come down for a long time, resulting in frequent occurrence of over-temperature phenomenon

[0009] 2) When the temperature of the main steam is lower than the set value, the cascade control system sometimes has the situation that the adjustment door is gradually opened, and the phenomenon of spraying water to reduce the temperature occurs, causing the temperature to rise below the set value for a long time

[0010] 3) After the combustion of the boiler deteriorates, there is no quick solution to the problem of sudden temperature rise and drop

[0011] 4) There is no effective solution to the serious nonlinear problem of tuning

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