CN113803707A - Supercritical unit double enthalpy difference correction water supply control method adapting to frequency modulation requirement - Google Patents
Supercritical unit double enthalpy difference correction water supply control method adapting to frequency modulation requirement Download PDFInfo
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- CN113803707A CN113803707A CN202111160645.8A CN202111160645A CN113803707A CN 113803707 A CN113803707 A CN 113803707A CN 202111160645 A CN202111160645 A CN 202111160645A CN 113803707 A CN113803707 A CN 113803707A
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- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000006243 chemical reaction Methods 0.000 claims description 6
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B35/00—Control systems for steam boilers
- F22B35/18—Applications of computers to steam boiler control
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B37/00—Component parts or details of steam boilers
- F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
- F22B37/38—Determining or indicating operating conditions in steam boilers, e.g. monitoring direction or rate of water flow through water tubes
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Abstract
The invention belongs to the technical field of water supply control methods, and particularly relates to a supercritical unit double enthalpy difference correction water supply control method adapting to frequency modulation requirements, wherein a primary water supply flow set value is obtained by multiplying main steam flow by an enthalpy difference correction coefficient of a superheater and then multiplying by a water wall water supply enthalpy difference correction coefficient; and the preliminary water supply flow set value is output by taking the water supply flow low protection value as a large value, and the output value is added with the superheat correction deviation to obtain the water supply flow set value. The control strategy realizes effective control of temperature under the frequency modulation requirement through double enthalpy value control.
Description
Technical Field
The invention belongs to the technical field of water supply control methods, and particularly relates to a supercritical unit double enthalpy difference correction water supply control method adapting to frequency modulation requirements.
Background
In recent years, the demand for frequency modulation of a thermal power unit is increasingly severe, the frequency modulation interval is short, the amplitude is large, the new current situation of frequency modulation in an ACE mode of the thermal power unit is achieved, the traditional thermal power unit is mainly controlled in a stable state, new requirements are provided for the frequency modulation capability of the thermal power unit along with the increase of new energy occupation year by year, the thermal power unit faces the contrast of double low situation of low electric quantity and low electricity price and high coal price, the conventional power generation operation is blocked, the frequency modulation benefit is a new profit point of the thermal power unit, the improvement of the frequency modulation capability of the thermal power unit is a necessary choice in the market, and the survival of the thermal power unit is also a necessary way.
The new energy of the frequency modulation of the thermal power generating unit is improved, and from the side of the steam turbine, only the influence factor of the deviation on the main control of the steam turbine needs to be increased, so that the steam turbine can rapidly act after receiving the load deviation caused by the frequency modulation, the steam quantity entering the steam turbine is increased or introduced, and the load can be rapidly adjusted. The quick action of the main control of the steam turbine is coordinated and controlled, if the main control of the boiler and the water supply control cannot respond in time, the main steam pressure and the temperature can fluctuate and oscillate greatly, and the safe operation of the unit is seriously influenced.
The traditional water supply control is coal-water ratio control, namely, the change of response load of the main control of the steam turbine is followed, the pressure change can be caused by the adjustment of steam flow quickly after the change of the response load of the main control of the steam turbine, at the moment, the main control of the boiler mainly realizes the change of main steam pressure brought by tracking and compensation through PID deviation adjustment while the coal supply quantity follows the change of load, the main control of the boiler is adjusted, and the water supply is correspondingly changed and adjusted along with the change of the coal quantity of the main control of the boiler so as to maintain the required water supply quantity. The traditional control is that the steam turbine tracks load change, the boiler maintains pressure balance, the feed water tracks boiler coal amount change, and the control has the advantages that: the steady state response characteristic is good, and the main steam temperature keeping effect is good. The adjustment of the coal feeding amount of the boiler needs longer time, the response time of the adjustment mode under the frequency modulation working condition is long, the pressure fluctuation is larger, and the frequency modulation performance is poor.
Disclosure of Invention
Aiming at the technical problems, the invention provides a double enthalpy difference correction water supply control method of a supercritical unit adapting to the frequency modulation requirement.
In order to solve the technical problems, the invention adopts the technical scheme that:
according to the double enthalpy difference correction water supply control method for the supercritical unit adapting to the frequency modulation requirement, the main steam flow is multiplied by an enthalpy difference correction coefficient of a superheater, and then is multiplied by a water cooling wall water supply enthalpy difference correction coefficient to obtain a preliminary water supply flow set value; and the preliminary water supply flow set value is output by taking the water supply flow low protection value as a large value, and the output value is added with the superheat correction deviation to obtain the water supply flow set value.
The superheat correction deviation is obtained by converting the deviation between the actual superheat and the target superheat through a deviation conversion function.
The designed enthalpy value of the water supply inlet is calculated in real time by selecting the actual pressure of the water wall inlet and the target temperature of the unit water supply.
And the actual enthalpy value of the outlet of the superheater is calculated in real time by selecting the average actual pressure of the main steam and the actual steam temperature of the superheater.
And the average actual pressure of the main steam and the target temperature of the superheater are selected as the target enthalpy value of the superheater outlet for real-time calculation.
The actual enthalpy value of the water supply outlet is calculated in real time by selecting the actual pressure and temperature of the outlet of the water cooling wall.
The target enthalpy value of the water supply outlet is calculated in real time by selecting the target temperature of the water supply outlet and the actual pressure of the water supply outlet.
Compared with the prior art, the invention has the following beneficial effects:
a double enthalpy difference correction water supply control strategy of a supercritical CFB unit, which meets the frequency modulation requirement, is provided. In order to respond to the frequency modulation requirement, the main steam pressure is inevitably subjected to rapid fluctuation after the main control response load of the steam turbine is subjected to high-frequency and deep amplitude change, and the main steam flow is selected for water supply basic quantity adjustment by utilizing the dynamic balance relation between the water supply flow and the main steam flow.
The main steam flow tracking rate can be obviously improved by adjusting and tracking the water supply quantity, the problems of overpressure and underpressure caused by load change can be quickly supplemented, the main steam temperature control effect is poor, and the problems of reverse regulation of pressure and temperature exist. The control strategy realizes effective control of temperature under the frequency modulation requirement through double enthalpy value control; the difficulty of temperature control is overcome, on one hand, the temperature control is directly output to the final stage to be influenced, and on the other hand, different conversion functions can be selected according to the characteristics of each power unit to adjust the influence quantity.
Drawings
FIG. 1 is a block diagram of a control method of the present invention;
FIG. 2 is a diagram showing the effect output of the feed water amount corresponding to the superheat temperature deviation according to the present invention;
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, in the method for controlling the double enthalpy difference correction water supply of the supercritical unit adapted to the frequency modulation requirement, the main steam flow is multiplied by the enthalpy difference correction coefficient of the superheater, and then the water wall water supply enthalpy difference correction coefficient is multiplied to obtain a preliminary water supply flow set value; and the preliminary water supply flow set value is output by taking the water supply flow low protection value as a large value, and the output value is added with the superheat correction deviation to obtain the water supply flow set value.
Further, the superheat correction deviation is obtained by converting the deviation between the actual superheat and the target superheat through a deviation conversion function.
The control logic is added with superheat correction deviation to finally output a water supply flow set value. The double enthalpy difference control method has the advantages that the effect of the enthalpy value calculated by utilizing the actual pressure on the whole energy is mainly controlled, the temperature control is ensured, and the system pressure effect is considered.
Because the control method of the steam-water ratio has good pressure fluctuation tracking effect and temperature control is difficult, on the basis of double enthalpy difference control, the superheat degree deviation correction is added, and only the temperature deviation is subjected to function conversion and superposed on the initial water supply flow fixed value.
Specifically, the method comprises the following steps: as shown in table 1 below and fig. 2, the conversion function is a feed water amount influence output corresponding to the superheat temperature deviation, and is a piecewise function based on y ═ kx + b.
TABLE 1
Specifically, the method comprises the following steps: the logic control is a control idea, and the detailed water supply control can superpose influence factors on the basis.
Further, the water supply flow set value utilizes the dynamic balance of the main steam flow and the water supply flow to adjust the basic quantity; the design enthalpy value of the water supply inlet selects the actual pressure of the water wall inlet and the target temperature of the unit water supply to calculate in real time; the actual enthalpy value of the outlet of the superheater is calculated in real time by selecting the average actual pressure of the main steam and the actual steam temperature of the superheater; the average actual pressure of main steam and the target temperature of the superheater are selected as the target enthalpy value of the superheater outlet for real-time calculation; the actual enthalpy value of the water supply outlet is calculated in real time by selecting the actual pressure and temperature of the outlet of the water cooling wall; the target enthalpy value of the water supply outlet is calculated in real time by selecting the target temperature of the water supply outlet and the actual pressure of the water supply outlet.
The superheater target temperature can be determined according to unit operating characteristics and is a fixed value conventionally, and if overtemperature frequently occurs to the boiler, the fixed value can be set and reduced. The target temperature of the water supply outlet is calculated by adding the correction of the unit characteristics according to the saturation temperature corresponding to the actual pressure of the outlet of the water cooling wall, the enthalpy of the outlet of the water supply design is more accurately reflected in real time, and meanwhile, the deviation of the design and the actual operation working condition of each unit can be offset by adding the unit characteristics.
Although only the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art, and all changes are encompassed in the scope of the present invention.
Claims (9)
1. The double enthalpy difference correction water supply control method of the supercritical unit adapting to the frequency modulation requirement is characterized by comprising the following steps:
multiplying the main steam flow by an enthalpy difference correction coefficient of a superheater, and multiplying by a water wall feed water enthalpy difference correction coefficient to obtain a preliminary feed water flow set value;
and the preliminary water supply flow set value is output by taking the water supply flow low protection value as a large value, and the output value is added with the superheat correction deviation to obtain the water supply flow set value.
2. The double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 1, characterized in that:
3. the double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 1, characterized in that:
4. the double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 1, characterized in that: the superheat correction deviation is obtained by converting the deviation between the actual superheat and the target superheat through a deviation conversion function.
5. The double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 1, characterized in that: the designed enthalpy value of the water supply inlet is calculated in real time by selecting the actual pressure of the water wall inlet and the target temperature of the unit water supply.
6. The double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 2, characterized in that: and the actual enthalpy value of the outlet of the superheater is calculated in real time by selecting the average actual pressure of the main steam and the actual steam temperature of the superheater.
7. The double enthalpy difference correction water supply control method for the supercritical unit meeting the frequency modulation requirement of claim 2, characterized in that: and the average actual pressure of the main steam and the target temperature of the superheater are selected as the target enthalpy value of the superheater outlet for real-time calculation.
8. The method for controlling the double enthalpy difference correction water supply of the supercritical unit according to the frequency modulation requirement is characterized in that: the actual enthalpy value of the water supply outlet is calculated in real time by selecting the actual pressure and temperature of the outlet of the water cooling wall.
9. The method for controlling the double enthalpy difference correction water supply of the supercritical unit according to the frequency modulation requirement is characterized in that: the target enthalpy value of the water supply outlet is calculated in real time by selecting the target temperature of the water supply outlet and the actual pressure of the water supply outlet.
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Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108443859A (en) * | 2018-04-04 | 2018-08-24 | 山西格盟安全生产咨询有限公司 | A kind of feedwater flow control method adapting to load rapid fluctuations |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108443859A (en) * | 2018-04-04 | 2018-08-24 | 山西格盟安全生产咨询有限公司 | A kind of feedwater flow control method adapting to load rapid fluctuations |
Non-Patent Citations (4)
| Title |
|---|
| 姜平;李丽锋;赵保国;王晋权;张海伟;任岐;: "ACE模式下超临界CFB机组协调控制策略的优化与应用", 工业仪表与自动化装置, no. 02 * |
| 段宝;范龙;李继宏;: "350MW超临界CFB机组RB控制技术分析", 发电设备, no. 01 * |
| 沈俭;: "600MW超超临界机组过热汽温控制策略与优化", 中国高新技术企业, no. 16 * |
| 葛克山;王群;: "横流式混合换热器中传质系数与压降的数学模型", 农机化研究, no. 03 * |
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