CN112096602B - Method for automatically controlling frequency conversion circulating water pump set of wet cooling steam turbine power generation set - Google Patents
Method for automatically controlling frequency conversion circulating water pump set of wet cooling steam turbine power generation set Download PDFInfo
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/06—Control using electricity
- F04B49/065—Control using electricity and making use of computers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/20—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by changing the driving speed
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
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Abstract
The invention discloses an automatic control method for a frequency conversion circulating water pump set of a wet cooling steam turbine generator set, and belongs to the field of automatic control of a cold end of a wet cooling steam turbine generator set. A method for automatically controlling a frequency conversion circulating water pump set of a wet cooling steam turbine power generation set comprises the following steps: a. acquiring data of current of each circulating water pump, high-voltage service voltage, circulating water supply temperature, electric power of a steam turbine generator unit and exhaust steam temperature by using a historical database; b. classifying by using electric power of a turbo generator set; c. obtaining a curve connected with the optimal switching point; d. recording the working condition curve into a DCS control system; e. comparing the actual running mode of the circulating water pump with the running mode of the circulating water pump; f. accumulating output and feedback deviations; according to the invention, through historical data analysis and processing, based on a DCS control system, the real-time automatic control of the variable-frequency circulating water pump set is realized, and the purpose of continuously and optimally operating the cold end system of the steam turbine is achieved.
Description
Technical Field
The invention relates to the technical field of automatic control of a cold end of a wet cooling unit, in particular to a method for automatically controlling a frequency conversion circulating water pump set of a power generation unit of a wet cooling steam turbine.
Background
The circulating water system is one of the important systems of the thermal power generation wet cooling unit, the circulating water pump is one of the most important power consumption consumers of a power plant, the improvement of the running economy of the circulating water system is one of the main directions of energy-saving work research all the time, in recent years, along with the increasing requirements on the main indexes of the thermal power plant, the performance indexes of the unit are fundamentally improved through frequency conversion modification to become the key point of technical modification of the thermal power plant, the application of the frequency conversion speed regulation technology on the circulating water pump of the thermal power plant is more and more extensive, and the frequency conversion regulation of the circulating water pump is gradually popularized in a new unit.
At present, in order to control the initial investment cost, a mode of combining a large pump and two small pumps is usually selected, wherein one small pump utilizes a frequency converter to adjust the rotating speed, the remaining two pumps are power frequency pumps, the full-load circulating water flow linear adjustment is realized, and the purpose of reducing the initial investment cost of the circulating water pump to the maximum extent is achieved, but the configuration of the circulating water pump can carry out full-load linear regulation on the flow of the circulating water, realize the highest economic benefit of the energy utilization rate of the thermal power plant, but how to quickly find the most economic operation mode of the circulating water pump and timely guide the field operation is a problem which needs to be solved urgently, in the actual production and operation process of the wet cooling unit, the operation mode of the circulating water pump set is subjectively estimated only by the working experience of operators on duty and the observation of a large number of cold end parameters, and the estimated operation mode has larger deviation with the optimal economic operation mode, low accuracy and poor timeliness.
Disclosure of Invention
The invention aims to solve the problems in the prior art and provides an automatic control method for a variable-frequency circulating water pump set of a power generation set of a wet cooling steam turbine.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for automatically controlling a frequency conversion circulating water pump set of a wet cooling steam turbine power generation set comprises the following steps:
a. acquiring data of current of each circulating water pump, high-voltage service voltage, circulating water supply temperature, electric power of a steam turbine generator unit and exhaust steam temperature by using a historical database;
b. classifying by using electric power of a steam turbine generator unit, calculating backpressure of a steam turbine by using an exhaust steam temperature, calculating a slight power increase of the steam turbine generator unit by using a backpressure load correction curve, when a circulating water supply water temperature sampling point is insufficient, performing correction by using the similar circulating water supply water temperature, then participating in calculation, comparing the economy of different circulating water pump operation modes at the same environmental temperature under the same electric power of the steam turbine generator unit, and performing accumulated iterative calculation to obtain an optimal working condition point for switching the circulating water pump operation modes under different loads;
c. taking the unit load as a horizontal coordinate and the circulating water supply temperature as a vertical coordinate to obtain a curve connecting the lower output limit of the circulating water pump set, the upper output limit of the circulating water pump set and the optimal switching points of the circulating water pump set in different running modes;
d. inputting the curve into a DCS control system, and acquiring the electric power of a real-time steam turbine generator unit and the supply water temperature of circulating water to obtain the operation mode of the circulating water pump and the frequency value of the variable-frequency circulating water pump;
e. comparing whether the actual running mode of the circulating water pump is consistent with the obtained running mode of the circulating water pump or not;
f. and outputting the deviation between the calculated frequency and the feedback frequency of the variable-frequency circulating water pump, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz.
Preferably, in the step a, a historical operating condition model is established by using historical database points.
Preferably, the turbine back pressure is calculated in step b using the turbine exhaust temperature.
Preferably, when the continuity of the circulating water supply temperature at the sampling point in the step b is not strong enough, the influence of the circulating water supply temperature in the performance test on the heat consumption of the wet cooling unit is corrected.
Preferably, in the step b, through analyzing the working condition of the circulating water pump group, the lower limit of the output of the circulating water pump group, the upper limit of the output of the circulating water pump group and the switching points of several different operation modes of the circulating water pump group are classified, meanwhile, 50%, 60%, 70%, 80%, 90% and 100% of rated electric load of a steam turbine generator unit are taken as nodes, when the working conditions of the same circulating water supply temperature are insufficient when the same electric load and the circulating water supply temperature are compared, the influence of the circulating water supply temperature in a performance test on the heat consumption of the unit is corrected, and the power consumption difference among the operation modes of the different circulating water pump groups is calculated by the high-pressure service power supply voltage and each current of the circulating water pump group; calculating the micro-power increase of the steam turbine generator unit by using a correction curve of backpressure to power; and performing iterative calculation on all working conditions under the load to find out the point with the maximum difference value as the optimal operation mode switching point of the circulating water pump set, and determining the optimal operation mode switching points of the circulating water pump sets of other electrical load nodes by analogy.
Preferably, in the step c, the operation curve of the circulating water pump group takes the electric load node of the steam turbine generator unit as the abscissa and the circulating water supply temperature as the ordinate, so as to obtain a curve connecting the lower output limit of the circulating water pump group, the upper output limit of the circulating water pump group and the optimal switching point of the circulating water pump group in different operation modes, namely the circulating water supply temperature switched by the operation modes of the circulating water pump group in the same load, and the curve is recorded into the automatic control program of the DCS.
Preferably, in the step d, the electric power of the steam turbine generator unit and the supply water temperature of the circulating water are input into an operation curve in an automatic control program of the DCS in real time, the operation mode of the circulating water pump set is output according to the point where the coordinate falls, and the frequency output is converted according to the equal proportion of the upper limit and the lower limit of the operation working condition interval of the circulating water pump set corresponding to the coordinate.
Preferably, in the step e, the actual running mode of the circulating water pump is compared with the running mode of the circulating water pump, and when the actual running mode of the circulating water pump is consistent with the running mode of the circulating water pump, the frequency conversion value is calculated.
Preferably, in the step e, comparing the actual circulating water pump operation mode with the obtained circulating water pump operation mode, and when the actual circulating water pump operation mode is inconsistent with the obtained circulating water pump operation mode, taking the real-time electric load as a fixed abscissa, and making a difference between the actual operation working point and the calculation working point ordinate, outputting the lowest frequency when the actual operation working point and the calculation working point are positive, and outputting the highest frequency when the actual operation working point and the calculation working point are negative.
Preferably, in the step f, when the calculated frequency and the feedback frequency of the variable-frequency circulating water pump are greater than 2Hz, a frequency instruction is output, the amplitude of the frequency instruction is 35-50Hz, and the change rate is not more than 5 Hz/min.
Compared with the prior art, the invention provides the automatic control method of the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set, which has the following beneficial effects:
1. the method for automatically controlling the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set comprises the steps of firstly utilizing a historical database to obtain current, high-voltage station service voltage, circulating water supply temperature, electric power of a steam turbine generator set and exhaust steam temperature data, then classifying the data by the electric power of the steam turbine generator set, utilizing the exhaust steam temperature to calculate back pressure of the steam turbine, utilizing a back pressure load correction curve to calculate micro-boost power of the steam turbine generator set, utilizing the exhaust steam temperature of the steam turbine to calculate the back pressure of the steam turbine, effectively amplifying the change amplitude of the back pressure, more accurately calculating the back pressure of the steam turbine, improving the overall calculation precision, taking the set load as a horizontal coordinate and the circulating water supply temperature as a vertical coordinate to obtain curves of connecting the lower output limit of the circulating water pump set, the upper output limit of the circulating water pump set and the optimal switching points of different running modes of the circulating water pump set, and inputting the curves into a DCS control system, collecting the electric power of the real-time turbo generator set and the supply water temperature of circulating water, obtaining the operation mode of the circulating water pump and the frequency value of the variable-frequency circulating water pump, then comparing the actual operation mode of the circulating water pump with the obtained operation mode of the circulating water pump, accumulating the output and feedback deviation, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz.
The invention aims at a system that the cold end of the steam turbine is provided with a large pump and a small pump to process a frequency conversion pump combination, realizes the real-time automatic control of a frequency conversion circulating water pump set through historical data analysis and processing and based on a DCS control system, and achieves the aim of continuously and optimally operating the system at the cold end of the steam turbine.
Drawings
FIG. 1 is a flow chart of a method for automatically controlling a frequency conversion circulating water pump set of a wet cooling steam turbine power generation set, which is provided by the invention;
FIG. 2 is a flow chart of a curve for calculating an optimal circulating water pump set operation mode in the present invention;
fig. 3 is a curve of the operation mode of the optimal variable-frequency circulating water pump set in the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.
Example (b):
referring to fig. 1 and 2, a method for automatically controlling a frequency conversion circulating water pump set of a wet cooling steam turbine power generation set comprises the following steps:
a. acquiring data of current of each circulating water pump, high-voltage service voltage, circulating water supply temperature, electric power of a steam turbine generator unit and exhaust steam temperature by using a historical database;
b. classifying by using electric power of a steam turbine generator unit, calculating backpressure of a steam turbine by using an exhaust steam temperature, calculating micro-boost power of the steam turbine generator unit by using a backpressure load correction curve, when a circulating water supply temperature sampling point is not enough, correcting by using similar circulating water supply temperature, participating in calculation, comparing economy of different circulating water pump operation modes at the same environmental temperature under the same electric power of the steam turbine generator unit, and obtaining an optimal working condition point for switching the circulating water pump operation modes under different loads by accumulated iterative calculation;
c. taking the unit load as a horizontal coordinate and the circulating water supply temperature as a vertical coordinate to obtain a curve connecting the lower output limit of the circulating water pump set, the upper output limit of the circulating water pump set and the optimal switching points of the circulating water pump set in different running modes;
d. inputting the curve into a DCS control system, and acquiring the electric power of a real-time steam turbine generator unit and the supply water temperature of circulating water to obtain the operation mode of the circulating water pump and the frequency value of the variable-frequency circulating water pump;
e. and comparing whether the actual running mode of the circulating water pump is consistent with the obtained running mode of the circulating water pump or not:
when the frequency difference is consistent with the frequency difference, calculating to obtain a frequency conversion value, performing output and feedback deviation accumulation, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz; when the real-time electric load is inconsistent, taking the real-time electric load as a fixed horizontal coordinate, subtracting the actual operating working condition point from the vertical coordinate of the calculation working condition point, outputting the lowest frequency when the actual operating working condition point is positive, and outputting the highest frequency when the actual operating working condition point is negative;
f. and outputting the deviation between the calculated frequency and the feedback frequency of the variable-frequency circulating water pump, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz.
And a step a, utilizing a historical database to take points to establish a historical working condition model.
And b, calculating the back pressure of the steam turbine by using the exhaust steam temperature of the steam turbine.
When the continuity of the circulating water supply temperature at the sampling point is not strong enough in the step b, correcting the influence of the circulating water supply temperature in the performance test on the heat consumption of the wet cooling unit; the base value of the iterative computation is expanded.
In the step b, through analyzing the working condition of the circulating water pump group, the lower output limit of the circulating water pump group, the upper output limit of the circulating water pump group and the circulating water pump group are provided, switching points of a plurality of different operation modes are classified, meanwhile, 50%, 60%, 70%, 80%, 90% and 100% of rated electric load of a steam turbine generator unit are taken as nodes, 50% of rated electric load is taken as an example, when the working condition of the same circulating water supply temperature is insufficient compared with the same electric load and the circulating water supply temperature, the influence of the circulating water supply temperature in a performance test on the heat consumption of the unit is corrected, and the power consumption difference among the operation modes of the different circulating water pump groups is calculated by the high-voltage service power supply voltage and each current of the circulating water pump group; calculating the micro-power increase of the steam turbine generator unit by using a correction curve of back pressure to power; and performing iterative calculation on all working conditions under the load to find out the point with the maximum difference value as the optimal operation mode switching point of the circulating water pump set, and determining the optimal operation mode switching points of the circulating water pump sets of other electrical load nodes by analogy.
In the step c, the circulating water pump set operation curve takes the electric load node of the steam turbine generator unit as a horizontal coordinate, and takes the circulating water supply temperature as a vertical coordinate, so as to obtain a curve connecting the lower output limit of the circulating water pump set, the upper output limit of the circulating water pump set and the optimal switching point of different operation modes of the circulating water pump set, namely the circulating water supply temperature switched by different circulating water pump set operation modes under the same load, and the curve is recorded into an automatic control program of the DCS.
Step d, inputting electric power of the steam turbine generator unit and the temperature of the circulating water supply to an operation curve in an automatic control program of the DCS in real time, outputting an operation mode of a circulating water pump set according to a point where a coordinate is located, and converting the operation mode into frequency output according to the upper limit and the lower limit of an operation working condition interval of the circulating water pump set corresponding to the coordinate in an equal proportion; acquiring the electric load x and the circulating water supply temperature y of the steam turbine generator unit in real time, and judging the optimal operation mode of the circulating water pump unit and the upper limit y1 and the lower limit y2 of the interval corresponding to the coordinate point y through the real-time acquired (x, y) located in the intervals of different curves;
and e, comparing the actual circulating water pump operation mode with the obtained circulating water pump operation mode, calculating to obtain a frequency conversion value when the actual circulating water pump operation mode is consistent with the obtained circulating water pump operation mode, outputting and feeding back to accumulate deviation, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz.
And e, comparing the actual circulating water pump operation mode with the obtained circulating water pump operation mode, and when the actual circulating water pump operation mode is inconsistent with the obtained circulating water pump operation mode, taking the real-time electric load as a fixed horizontal coordinate, making a difference between the actual operation working condition point and the calculation working condition point vertical coordinate, outputting the lowest frequency when the actual operation working condition point and the calculation working condition point are positive, and outputting the highest frequency when the actual operation working condition point and the calculation working condition point are negative.
And comparing the actual operation mode with the optimal operation mode of the circulating water pump set: if the operation modes are consistent, outputting the frequency obtained in the second step, and solving the output frequency through the following equation:
f＝(y-y2)(fmax-fmin)/(y1-y2)；
comparing the actual operation mode of the circulating water pump set with the optimal operation mode, and if the operation modes are inconsistent and the ordinate ymin of the actual operation mode is more than y, outputting the frequency fmin; when the ordinate ymax of the actual operation mode is less than y, the output frequency is fmax, wherein fmax is 50Hz, fmin is 35Hz, and the maximum change rate is not more than 5Hz per minute;
and f, when the calculation frequency and the feedback frequency of the variable-frequency circulating water pump are greater than 2Hz, outputting a frequency instruction, wherein the amplitude of the frequency instruction is 35-50Hz, and the change rate is not more than 5 Hz/min.
Referring to fig. 2, a cold-end data processing method in an embodiment of the present application; the historical data processing method takes a historical database as basic data, takes unit performance test data as support, and obtains a basic data processing basis: extracting the electric load of a steam turbine generator unit, the supply water temperature of circulating water, the exhaust temperature of a low-pressure cylinder, the current of each circulating water pump and the high-voltage service voltage in a historical database as historical working condition data, and carrying out classified statistics on the historical working conditions of the 6 nodes by using the electric load; wherein, the historical data extraction needs to be carried out with vacuum tightness for screening so as to eliminate the influence of uncontrollable factors;
the method comprises the following steps of performing auxiliary calculation by utilizing a backpressure heat consumption correction curve obtained in a performance test, steam turbine efficiencies of different loads and the influence of circulating water supply temperature on the heat consumption of a steam turbine, calculating the backpressure of the steam turbine under a working condition by using the exhaust temperature of a low-pressure cylinder in the historical working condition of classified statistics, and neglecting the interference of the precision of a measured point of a vacuum measuring point and the environment; selecting two different operating mode working conditions of a circulating water pump set under the same circulating water supply temperature, correcting the supply water temperature by the influence of the circulating water supply temperature on the heat consumption of the steam turbine when the historical working condition point of the circulating water supply temperature is not enough, and calculating the micro-power increase of the generator by using a backpressure heat consumption correction curve:
the heat consumption can be expressed as a percentage of the effect obtained in the performance test, for example: if the circulating water supply temperature affects 1% of heat consumption, the calculation method is that delta N is (1% -1) P0;
calculating the power consumption of the circulating water pump according to the current of each circulating water pump and the high-voltage service voltage, and obtaining the power consumption increment of the circulating water pump set in different running modes:
Δ P＝P' circulation type -P Circulation of
Making a difference between the slightly increased power of the generator and the power consumption increment of the circulating water pump set:
F max ＝ Δ P+ Δ N
repeating the steps, obtaining economic comparison of the circulating water pump sets under the condition of multiple different circulating water supply temperatures, and obtaining the working condition of the maximum value of the power increment difference value of the generator micro-power increment and the circulating water pump sets through comparison, namely the optimal working condition point of the circulating water pump sets for switching the operation mode under the electric load;
and linearly collecting the working condition points in the fifth step, taking the electric load (x) as a horizontal coordinate, taking the circulating water supply temperature (y) as a vertical coordinate, and operating different circulating water pump sets in an optimal mode.
In this embodiment, the relation between the temperature of the circulating water supplied by the historical data processing method and the back pressure and heat consumption of the steam turbine may be obtained in other ways besides the above method, and expressed in a functional way.
In this embodiment, the cooling medium may be water or air, or other low-temperature cooling medium, and the cooling medium supply device may be a fan, a water pump, or other combined cooling device.
In the running process of the automatic program, the optimal running mode curve of the control system only needs to be written once, automatic control can be realized without subsequent operation of operators, and when the actual equipment on site has larger running condition change, iteration can be carried out through the steps, relevant parameters in the program are changed, and real-time matching between the automatic control system and the site is realized.
The actual operation mode of the field equipment is judged through comprehensive conditions, automatic system misjudgment caused by abnormal operation of the equipment is prevented, and the operation conditions of each circulating water pump are as follows: the high-pressure switch closing and frequency converter closing and outlet hydraulic control butterfly valve full opening and high-pressure switch current of the circulating water pump does not exceed the upper and lower operation limits.
The embodiment of the application takes a 350MW unit to be equipped with three circulating water pumps as an example, a 50% capacity power frequency pump (for short, a large pump), a 25% capacity power frequency pump (for short, a small pump), a 25% capacity variable frequency pump (for short, a variable frequency pump), coexists in four kinds of operating condition, need following five curves: the curve of figure 3 can be obtained by processing the data, and the curve of figure 3 is written into a DCS control system as a core calculation flow to automatically control the variable-frequency circulating water pump set.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered as the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (8)
1. A method for automatically controlling a frequency conversion circulating water pump set of a wet cooling steam turbine power generation set is characterized by comprising the following steps:
a. acquiring data of current of each circulating water pump, high-voltage service voltage, circulating water supply temperature, electric power of a steam turbine generator unit and exhaust steam temperature by using a historical database;
b. classifying by using electric power of a steam turbine generator unit, calculating backpressure of a steam turbine by using an exhaust steam temperature, calculating micro-boost power of the steam turbine generator unit by using a backpressure load correction curve, when a circulating water supply temperature sampling point is not enough, correcting by using similar circulating water supply temperature, participating in calculation, comparing economy of different circulating water pump operation modes at the same environmental temperature under the same electric power of the steam turbine generator unit, and obtaining an optimal working condition point for switching the circulating water pump operation modes under different loads by accumulated iterative calculation;
c. taking the unit load as a horizontal coordinate and the circulating water supply temperature as a vertical coordinate to obtain a curve connecting the lower output limit of the circulating water pump set, the upper output limit of the circulating water pump set and the optimal switching points of the circulating water pump set in different running modes;
d. inputting the curve into a DCS (distributed control system), and acquiring the electric power of a real-time steam turbine generator unit and the water supply temperature of circulating water to obtain the operation mode of the circulating water pump and the frequency value of the variable-frequency circulating water pump;
e. comparing whether the actual running mode of the circulating water pump is consistent with the obtained running mode of the circulating water pump or not:
when the frequency values are consistent, calculating to obtain a frequency conversion value;
when the real-time electric load is inconsistent, taking the real-time electric load as a fixed horizontal coordinate, subtracting the actual operating working condition point from the vertical coordinate of the calculation working condition point, outputting the lowest frequency when the actual operating working condition point is positive, and outputting the highest frequency when the actual operating working condition point is negative;
f. and outputting the deviation between the calculated frequency and the feedback frequency of the variable-frequency circulating water pump, and sending out a frequency automatic control instruction when the deviation is more than 2 Hz.
2. The method for automatically controlling the variable-frequency circulating water pump set of the wet cooling steam turbine power generation set according to claim 1, wherein a historical working condition model is established by using historical database points.
3. The method for automatically controlling the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set according to claim 1, wherein the back pressure of the steam turbine is calculated in the step b by using the exhaust steam temperature of the steam turbine.
4. The method for automatically controlling the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set according to claim 3, wherein when the continuity of the circulating water supply temperature at the sampling point in the step b is not strong enough, the influence of the circulating water supply temperature in the performance test on the heat consumption of the wet cooling unit is corrected.
5. The method according to claim 4, wherein in the step b, through analysis of the working condition of the circulating water pump group, the lower limit of the output of the circulating water pump group, the upper limit of the output of the circulating water pump group and the switching point classification of several different operation modes of the circulating water pump group are provided, and at the same time, 50%, 60%, 70%, 80%, 90% and 100% of the rated electric load of the steam turbine generator group are used as nodes, when the working condition of the same circulating water supply temperature is insufficient when the same electric load and the circulating water supply temperature are compared, the influence of the circulating water supply temperature in the performance test on the heat consumption of the steam turbine generator group is corrected, and the power consumption difference between the operation modes of different circulating water pump groups is calculated by the high-voltage service voltage and the currents of the circulating water pump group; calculating the micro-power increase of the steam turbine generator unit by using a correction curve of back pressure to power; and performing iterative calculation on all working conditions under the load to find out the point with the maximum difference value as the optimal operation mode switching point of the circulating water pump set, and determining the optimal operation mode switching points of the circulating water pump sets of other electrical load nodes by analogy.
6. The method according to claim 1, wherein in step c, the operating condition curve of the circulating water pump set takes the electrical load node of the steam turbine generator set as the abscissa and the supply water temperature of the circulating water as the ordinate, so as to obtain a curve connecting the lower limit of the output of the circulating water pump set, the upper limit of the output of the circulating water pump set and the optimal switching point of the different operating modes of the circulating water pump set, that is, the supply water temperature of the circulating water switched by the operating modes of the different circulating water pump sets under the same load, and the curve is recorded into the automatic control program of the DCS.
7. The method for automatically controlling the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set according to claim 1, wherein in the step d, the electric power of the steam turbine generator set and the supply water temperature of the circulating water are input to an operation curve in an automatic control program of a DCS system in real time, the operation mode of the circulating water pump set is output according to a coordinate located point, and the frequency output is converted according to the equal proportion of the upper limit and the lower limit of the operation working condition interval of the circulating water pump set corresponding to the coordinate.
8. The method for automatically controlling the frequency conversion circulating water pump set of the wet cooling steam turbine power generation set according to claim 1, wherein in the step f, when the deviation between the calculation frequency and the feedback frequency of the frequency conversion circulating water pump is larger than 2Hz, a frequency command is output, the amplitude of the frequency command is 35-50Hz, and the change rate is not more than 5 Hz/min.
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| CN113513746B (en) * | 2021-04-26 | 2023-02-28 | 中国大唐集团科学技术研究院有限公司华东电力试验研究院 | Method for determining optimized operation mode of closed circulating water system of thermal power plant |
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