CN-121976865-A - NDC system load follow-up regulation and control method and system

CN121976865ACN 121976865 ACN121976865 ACN 121976865ACN-121976865-A

Abstract

The invention relates to a load follow-up regulation and control method and a system of an NDC (non-linear thermal storage) system, which belong to the technical field of air cooling of coal-fired power plants and comprise the following steps of judging that the actual back pressure of steam turbine exhaust is high or low in back pressure, the actual load of a unit is an ascending load trend or a descending load trend and the comprehensive opening of a shutter of a running cooling sector, so as to form a steam side input of the cooling sector, an air side exit of the cooling sector and a steam side exit instruction of the cooling sector.

Inventors

ZHANG XIAOBING
BAI HAIJUN
CHEN QIANG
Wei Jiongming
LI PING
HU XIAOGANG
LI GUORUI
Jiang Ruo

Assignees

陕西榆林能源集团杨伙盘煤电有限公司

Dates

Publication Date: 20260505
Application Date: 20260226

Claims (10)

1. The NDC system load follow-up regulation and control method is applied to a natural ventilation direct air cooling system and is characterized by comprising the following steps of: Judging the actual back pressure of the steam turbine exhaust is high or low; Judging whether the actual load of the unit is an ascending load trend or a descending load trend; obtaining the comprehensive opening degree of the shutter of the operational cooling sector; When the actual back pressure of the exhaust steam of the steam turbine is high, the actual load of the unit is an ascending load trend, and the comprehensive opening of the shutter of the current operation cooling sector is more than 50%, the steam side of the cooling sector is put into operation; when the steam side of the cooling sector is put into operation, the actual back pressure of the steam turbine exhaust is high, and the comprehensive opening of the shutter of the current operation cooling sector is more than 60 percent, the air side of the cooling sector is put into operation; When the actual back pressure of the exhaust steam of the steam turbine is low, the actual load of the unit is a load-reducing trend, and the comprehensive opening of the shutter of the current operation cooling sector is less than 40%, the air side of the cooling sector exits; when the cooling sector air side exit is completed, the cooling sector vapor side also exits.
2. The NDC system load follow-up regulation method of claim 1, wherein the determining that the actual back pressure of the exhaust steam of the steam turbine is a high back pressure or a low back pressure comprises: Obtaining the set back pressure of the steam turbine exhaust according to the load-back pressure curve of the natural ventilation direct air cooling system and the ambient temperature; when the actual back pressure of the steam turbine exhaust-the set back pressure of the steam turbine exhaust is more than or equal to 0.5kPa, judging that the actual back pressure of the steam turbine exhaust is high; and when the actual back pressure of the steam turbine exhaust is less than or equal to-1 kPa, the actual back pressure of the steam turbine exhaust is judged to be low.
3. The NDC system load follow-up regulation method of claim 1, wherein the determining that the actual load of the unit is an up-load trend or a down-load trend comprises: When the AGC instruction load-actual load is more than or equal to 5MW, judging that the actual load of the unit is an ascending load trend; When the AGC command load-actual load is less than or equal to-5 MW, the actual load of the unit is judged to be the load-reducing trend.
4. The NDC system load follow-up regulation and control method of claim 1, wherein the comprehensive opening degree of the operational cooling sector shutter is obtained by obtaining the sum of the opening degrees of all operational cooling sector shutters of the natural ventilation direct air cooling system and then utilizing the opening degrees of all operational cooling sector shutters and/or the number of all operational cooling sector shutters.
5. The NDC system load follow-up regulation and control method according to claim 1, wherein the steam side input of the cooling sector is implemented by firstly opening a condensate drain valve and then opening a steam isolation valve, the steam side input of the cooling sector is completed under the condition that the condensate drain valve and the steam isolation valve are completely opened and the condensate temperature of the cooling sector is more than or equal to 40 ℃, and the air side input of the cooling sector is implemented by opening a shutter at a speed of 15% -20% -min until the opening of the shutter is equal to a command value of the total operation output opening of the back pressure.
6. The NDC system load follow-up control method of claim 5, wherein when the steam side of the cooling sector is put into operation, if any one of the condensate drain valve and the steam isolation valve is not fully opened within 5 minutes, the steam side of the cooling sector is determined to be blocked, the next cooling sector is put into operation directly after the steam isolation valve of the cooling sector is fully closed, and when the air side of the cooling sector is put into operation, if the opening of the shutter is still less than 30% after 5 minutes, the air side of the cooling sector is determined to fail to put into operation, and the next cooling sector is put into operation directly.
7. The NDC system load follow-up regulation and control method of claim 1, wherein the cooling sector air side exit adopts a shutter closed at a speed of 10%/min until the shutter of the cooling sector is completely closed, and the cooling sector steam side exit adopts a shutter closed after the shutter of the cooling sector is completely closed for 2min, and a condensate drain valve is closed after the shutter of the cooling sector is completely closed for 10 min.
8. The NDC system load follow-up regulation and control method of claim 7, wherein when the shutter is closed for 5min and is still not fully closed when the air side of the cooling sector exits, the air side of the cooling sector is judged to be blocked, and the shutter of the cooling sector is re-opened until the opening of the shutter is equal to the instruction value of the total operation output opening of the back pressure.
9. The NDC system load follow-up control method of claim 1, wherein when the cooling sector is put in, the cooling sector which is not put in and is positioned at the side of the steam exhaust main pipe close to the steam turbine is put in preferentially, the next cooling sector is put in along the steam flow direction in the steam exhaust main pipe after the cooling sector is put in, when the cooling sector is put out, the cooling sector which is put in and is positioned at the side of the steam exhaust main pipe far from the steam turbine is put out preferentially, and the next cooling sector is put out along the opposite direction of the steam flow in the steam exhaust main pipe after the cooling sector is put out.
10. An NDC load follow-up regulation system, comprising: the acquisition module is used for acquiring the actual back pressure of the steam turbine exhaust, the set back pressure of the steam turbine exhaust, the actual load of the unit, the opening degree of the shutter of all the operational cooling sectors, the condensation water temperature of the cooling sectors and the environmental temperature; The first processing module is used for judging whether the actual back pressure of the steam turbine exhaust is high or low in back pressure, whether the actual load of the unit is an ascending load trend or a descending load trend and the comprehensive opening degree of the louver of the cooling sector during operation according to the obtained actual back pressure of the steam turbine exhaust, the set back pressure of the steam turbine exhaust, the actual load of the unit, the opening degree of the louver of all the cooling sectors during operation, the condensation water temperature of the cooling sector and the environmental temperature; and the second processing module is used for automatically switching the cooling sector of the natural ventilation direct air cooling system according to the fact that the actual back pressure of the exhaust steam of the steam turbine is high or low, the actual load of the unit is an ascending load trend or a descending load trend and the comprehensive opening of the louver of the cooling sector during operation.

Description

NDC system load follow-up regulation and control method and system Technical Field The invention belongs to the technical field of air cooling of coal-fired power plants, and particularly relates to a load follow-up regulation and control method and system of an NDC (non-linear thermal coefficient) system. Background With the development of air cooling technology in recent years, natural ventilation direct air cooling (NDC) systems have been successfully applied in engineering practice with their excellent economic and environmental benefits. The natural ventilation direct air cooling system is provided with a natural ventilation cooling tower, a steam turbine, a steam exhaust main pipe and a plurality of cooling sectors are arranged in the tower, one end of the steam exhaust main pipe is communicated with the steam turbine, the cooling sectors are arranged along the length direction of the steam exhaust main pipe and are communicated with the steam turbine, each cooling sector is provided with a steam isolation valve and a condensate drain valve, each sector corresponds to a group of shutters, steam exhaust of the steam turbine enters the cooling sector heat exchange pipe through the steam exhaust main pipe, cold air flows upwards from the bottom of the tower and enters the shutters to pass through the outer side of the cooling sector heat exchange pipe, so that the cold air exchanges heat with steam exhaust in the cooling sector heat exchange pipe, hot air after heat exchange leaves the cooling tower through the tower top, and steam in the cooling sectors is condensed into water and then returns to a regenerative system of the steam turbine through a condensation pump. With the steady increase of the new energy in the duty ratio of the electric power system, the novel electric power system is constructed and rapidly propelled, and in the upgrading action of the coal motor group, higher requirements are provided for cleaning and reducing carbon, safety and reliability, high-efficiency regulation and intelligent operation. When the load of the coal motor unit changes, the cooling sector of the natural ventilation direct air cooling system also needs to conduct switching response, the switching of the cooling sector comprises steam side switching and air side switching, wherein the steam side switching is to open or close a steam isolation valve and a condensation water drain valve, and the air side switching is to open or close a shutter. When the existing natural ventilation direct air cooling system responds and adjusts the cooling sector, a monitoring staff judges whether the cooling sector is put into or out of according to parameters such as overall unit load, back pressure of the steam turbine, shutter opening, ambient temperature and the like by combining with own experience. However, in the actual monitoring process of the system, the monitoring staff has great difficulty in overall planning of the series of parameters, and is difficult to quickly and accurately judge whether the cooling sector is put into or withdrawn from the system, so that the response adjustment of the air cooling system is delayed from the load change of the unit, and the natural ventilation direct air cooling system cannot meet the higher load follow-up regulation and control requirement of the coal motor group. Disclosure of Invention In view of this, the present invention provides a method and a system for controlling load of NDC system in a follow-up manner, so as to solve the defects in the prior art, the invention can timely switch the cooling sector of the natural ventilation direct air cooling system when the unit changes load, quickly respond to the load demand of the unit and meet the higher load follow-up regulation and control requirement of the coal motor unit. The technical scheme of the invention is that the NDC system load follow-up regulation and control method is applied to a natural ventilation direct air cooling system, and comprises the following steps: Judging the actual back pressure of the steam turbine exhaust is high or low; Judging whether the actual load of the unit is an ascending load trend or a descending load trend; obtaining the comprehensive opening degree of the shutter of the operational cooling sector; When the actual back pressure of the exhaust steam of the steam turbine is high, the actual load of the unit is an ascending load trend, and the comprehensive opening of the shutter of the current operation cooling sector is more than 50%, the steam side of the cooling sector is put into operation; when the steam side of the cooling sector is put into operation, the actual back pressure of the steam turbine exhaust is high, and the comprehensive opening of the shutter of the current operation cooling sector is more than 60 percent, the air side of the cooling sector is put into operation; When the actual back pressure of the exhaust steam of the steam turbine is low, the actual load of the un