CN-122018284-A - Automatic control method and system for parallel equipment of thermal power plant

CN122018284ACN 122018284 ACN122018284 ACN 122018284ACN-122018284-A

Abstract

The invention relates to the technical field of equipment control of thermal power plants, and provides an automatic control method and an automatic control system for parallel equipment of a thermal power plant, which are applied to a system for jointly adjusting the same regulated quantity through a first regulating valve and a second regulating valve, wherein the first regulating valve adopts a closed-loop control mode and is regulated based on the deviation between a set value and an actual value of the regulated quantity, the opening degree of the first regulating valve is monitored, when the opening degree of the first regulating valve is lower than a preset first threshold value or higher than a preset second threshold value, the second regulating valve is subjected to open-loop stepping regulation for changing the regulated quantity, and the opening degree of the first regulating valve is reversely regulated through a closed-loop control loop of the first regulating valve so as to return to a preset interval formed by the first threshold value and the second threshold value. The scheme improves the adjustment quality of a single device and ensures the reliability and efficiency of a parallel device system under complex operation conditions.

Inventors

ZHAO LONGWEI
SUN JIANGUO
LI YUENAN
LIU YONGJIE
QI RU

Assignees

内蒙古聚达发电有限责任公司

Dates

Publication Date: 20260512
Application Date: 20260316

Claims (10)

1. The automatic control method for the parallel equipment of the thermal power plant is applied to a system for jointly adjusting the same adjusted quantity through a first adjusting valve and a second adjusting valve and is characterized by comprising the following steps that the first adjusting valve adopts a closed-loop control mode and adjusts based on the deviation between a set value and an actual value of the adjusted quantity; The method comprises the steps of monitoring the opening of a first regulating valve, executing open-loop stepping adjustment on a second regulating valve when the opening of the first regulating valve is lower than a preset first threshold value or higher than a preset second threshold value, and changing the regulated quantity, wherein the change of the regulated quantity is used for reversely adjusting the opening of the first regulating valve through a closed-loop control loop of the first regulating valve so as to enable the opening of the first regulating valve to return to a preset interval formed by the first threshold value and the second threshold value.
2. The method for automatically controlling parallel equipment of a thermal power plant according to claim 1, wherein the step-open adjustment of the second regulating valve comprises the steps of decreasing the opening command of the second regulating valve according to a preset step when the opening of the first regulating valve is lower than a first threshold value, and increasing the opening command of the second regulating valve according to a preset step when the opening of the first regulating valve is higher than a second threshold value.
3. The automatic control method of parallel equipment of a thermal power plant according to claim 2, wherein the preset step size is an opening degree variation of 2% of a fixed step size.
4. The method for automatically controlling parallel equipment of a thermal power plant according to claim 1, wherein a preset waiting time is maintained after each time of the open loop step adjustment, and after the response of the adjusted quantity and the opening of the first regulating valve is stable, whether the opening of the first regulating valve is still outside the preset interval is judged again, and if yes, the next step adjustment is continuously executed.
5. The automatic control method of parallel equipment of a thermal power plant according to claim 4, wherein the preset waiting time is 60s.
6. The automatic control method for parallel equipment of a thermal power plant according to claim 1, further comprising setting a minimum opening limit for said second regulating valve, said minimum opening limit value being determined according to a unit operation load.
7. The automatic control method of parallel equipment of a thermal power plant according to claim 6, wherein the unit operation load and the minimum opening limit value are determined through a preset corresponding relation or obtained through an interpolation mode when the load changes.
8. The automatic control method for parallel equipment of a thermal power plant according to claim 1, further comprising interlock control logic for forcing the regulating function of the second regulating valve to be put into automatic mode when the first regulating valve is put into automatic mode, and forcing the first regulating valve to be switched to manual mode when the second regulating valve is switched to manual mode.
9. An automatic control system of parallel equipment of a thermal power plant is used for realizing the control method in any one of the steps 1-8, and is characterized by comprising a first adjusting module, a state monitoring module, a second adjusting module, a minimum opening protection module, an interlocking control module and an abnormality processing module; The first regulating module comprises a PID controller and a first regulating valve, is used for performing closed-loop control on the first regulating valve to regulate the first regulating valve based on the deviation between a set value of a regulated quantity and an actual value, is electrically connected with a detecting mechanism of the first regulating valve and is used for monitoring the opening degree of the first regulating valve in real time, and is electrically connected with the state monitoring module and an executing mechanism of the second regulating valve respectively and is used for executing open-loop stepping regulation on the second regulating valve when the opening degree of the first regulating valve is lower than a first threshold value or higher than a second threshold value; The minimum opening protection module is electrically connected with the second adjusting module and the unit load respectively, and is used for forcedly limiting an output instruction to the minimum opening and generating an alarm signal when the adjusting instruction output by the second adjusting module is smaller than the preset minimum opening; the interlocking control module is respectively and electrically connected with the first adjusting module and the second adjusting module and is used for realizing signal interlocking of the first adjusting valve and the second adjusting valve; The abnormality processing module is electrically connected with the state monitoring module, the first adjusting module and the second adjusting module and is used for monitoring abnormal conditions in real time; The opening degree of the first regulating valve is reversely regulated through a closed-loop control loop of the first regulating valve, so that the opening degree of the first regulating valve returns to a preset interval formed by the first threshold value and the second threshold value.
10. A parallel equipment automatic control system of a thermal power plant is characterized in that the mode of performing open loop stepping adjustment by the second adjusting module comprises the steps of reducing an opening instruction of the second adjusting valve according to a preset step length when the opening of the first adjusting valve is lower than a first threshold value, and increasing the opening instruction of the second adjusting valve according to the preset step length when the opening of the first adjusting valve is higher than a second threshold value.

Description

Automatic control method and system for parallel equipment of thermal power plant Technical Field The invention relates to the technical field of equipment control of thermal power plants, in particular to an automatic control method and system for parallel equipment of a thermal power plant. Background In a thermal power plant, parallel equipment (such as a plurality of water supply pumps, a draught fan, a high-pressure/low-pressure heat exchanger, a circulating water pump and the like) is a core component of a thermodynamic system and an auxiliary machine system. The automatic control of the equipment has the core aims of realizing load balance distribution, fault redundancy switching and stable and efficient system, thereby avoiding system fluctuation caused by overload or insufficient output of a single equipment. At present, the widely adopted technology is distributed control system DCS hierarchical control, wherein the system uniformly distributes load to each parallel device according to total requirements (such as boiler water supply amount and hearth air supply amount) by combining rated capacity or efficiency characteristics of each device, and long-term expiration load operation (service life shortening) or low-load operation (low efficiency) of a single device is avoided. The control architecture is generally "total load instruction issue→in-situ control layer (single device adjustment)", so as to implement multi-device cooperation. For example, after the central control layer issues the command of total air supply quantity 80000m3/h, the local layer automatically distributes the output of each fan 40000m3/h according to the rated capacity proportion of the two fans, and adjusts the rotating speed of the fans. Although the existing methods are mature in terms of generation and distribution of the total load command, they generally rely on conventional PID closed loop control after the command is issued to a single device. However, as the equipment runs and ages for a long time, the dynamic characteristics of the equipment often change, so that the regulation performance is reduced, and the problems of response delay, overshoot or oscillation and the like occur. If the PID control strategy with fixed parameters is continuously used, not only is accurate adjustment difficult to realize, but also fluctuation of equipment and systems is possibly aggravated, and the stability and economy of the whole operation are affected. Disclosure of Invention In order to solve the problems in the background art, the invention provides an automatic control method and system for parallel equipment of a thermal power plant, which improves the adjustment quality of single equipment and ensures the reliability and efficiency of a parallel equipment system under complex operation conditions. In order to achieve the above purpose, the present invention adopts the following scheme: An automatic control method of parallel equipment of a thermal power plant is applied to a system for jointly adjusting the same adjusted quantity through a first adjusting valve and a second adjusting valve, and comprises the steps of adjusting the first adjusting valve in a closed-loop control mode based on deviation between a set value and an actual value of the adjusted quantity, monitoring the opening of the first adjusting valve, executing open-loop stepping adjustment on the second adjusting valve when the opening of the first adjusting valve is lower than a preset first threshold value or higher than a preset second threshold value, and changing the adjusted quantity, wherein the change of the adjusted quantity is used for reversely adjusting the opening of the first adjusting valve through a closed-loop control circuit of the first adjusting valve, so that the opening of the first adjusting valve returns to a preset interval formed by the first threshold value and the second threshold value. Optionally, the step-open adjustment of the second regulating valve comprises the steps of reducing the opening instruction of the second regulating valve according to a preset step length when the opening of the first regulating valve is lower than a first threshold value, and increasing the opening instruction of the second regulating valve according to a preset step length when the opening of the first regulating valve is higher than a second threshold value. Optionally, the preset step length is an opening degree variation of 2% of the fixed step length. Optionally, after the open loop step adjustment is executed each time, maintaining a preset waiting time, after the adjusted quantity and the opening response of the first regulating valve are stable, judging again whether the opening of the first regulating valve is still outside the preset interval, if so, continuing to execute the next step adjustment. Optionally, the preset waiting time is 60s. Optionally, a minimum opening limit is set for the second regulating valve, and the minimum op