CN109236391B - Method for calculating peak regulation range of cogeneration unit - Google Patents

Method for calculating peak regulation range of cogeneration unit Download PDF

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CN109236391B
CN109236391B CN201811055140.3A CN201811055140A CN109236391B CN 109236391 B CN109236391 B CN 109236391B CN 201811055140 A CN201811055140 A CN 201811055140A CN 109236391 B CN109236391 B CN 109236391B
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unit
heat supply
load
steam
flow
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CN109236391A (en
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郭瑞君
张国斌
张叔禹
刘永江
王彪
辛晓钢
杜荣华
秦成果
党少佳
周磊
李旭
殷建华
高正平
张谦
武文华
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Inner Mongolia Electric Power Research Institute of Inner Mongolia Power Group Co Ltd
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Inner Mongolia Electric Power Research Institute of Inner Mongolia Power Group Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • F01D21/003—Arrangements for testing or measuring
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
    • F24D19/00—Details
    • F24D19/10—Arrangement or mounting of control or safety devices

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Abstract

The invention discloses a method for calculating a peak regulation range of a cogeneration unit, which comprises the following steps: according to the thermal characteristic data and the heat supply steam extraction flow of the cogeneration generator set, respectively fitting and determining an AGC maximum output load line of the generator set, a boiler minimum stable combustion output load line and a minimum power generation load line of the generator set under a heat supply working condition by taking the heat supply steam extraction flow of the generator set as an X axis and the power generation load of the generator set as a Y axis; and step two, calculating a unit AGC schedulable generating load lower limit, a unit AGC schedulable generating load upper limit and a unit AGC schedulable generating load range under any heat supply steam extraction flow according to the unit AGC maximum output load line, the boiler minimum stable combustion output load line and the unit minimum generating load line under the heat supply working condition which are determined by fitting in the step one. The invention can expand the lower limit of the unit load as much as possible by calculating the minimum schedulable power generation load on line, and achieves the purpose of improving the deep peak regulation capability of the power grid in the heat supply period.

Description

Method for calculating peak regulation range of cogeneration unit
Technical Field
The invention belongs to the technical field of power generation control of large cogeneration units, and particularly relates to a method for calculating a peak shaving range of a cogeneration unit.
Background
In recent years, the installed capacity of wind power is continuously increased, the installed capacity is mainly concentrated in the three north areas, but in the areas, particularly in the north areas such as northeast and inner Mongolia areas, the proportion of large-scale cogeneration units in a power grid is high, but the peak regulation capacity is limited, and the contradiction between heat supply, a strong wind period and a dry water period in winter is prominent, so that the condition of wind abandon in winter is serious; and along with the increasing of the peak-valley difference of the power load, especially in the heat supply period in winter, the power generation load interval of the power grid to the unit which can be dispatched is very small, so that the pure condensing unit in the power grid is frequently started and stopped in order to maintain the power flow balance of the power grid, the stability and the economy of the condensing unit under the deep peak-dispatching working condition become very poor, the average energy consumption level of the generating unit in the power grid is increased, and the method is not economical and wastes a lot. The peak regulation capability of the cogeneration unit is more scientifically scheduled and fully excavated, so that the cogeneration unit can safely participate in the deep peak regulation of the power grid, which is a problem to be solved urgently.
The cogeneration unit simultaneously bears two loads of power generation and heat supply, in the past, because the unilateral emphasis on heat supply safety is put on, the electric load scheduling of the cogeneration unit is carried out by a mode of determining output according to the maximum heat supply load, the lower limit of scheduling is very high, and the peak regulation capacity of the cogeneration unit cannot be fully exerted; the condition that the lower limit of the electric load is checked and determined for scheduling by the short-time peak heat supply amount is changed, the unit electric load scheduling interval is changed from fixed to dynamic change, and the power grid scheduling can directly master the heat supply condition and the peak regulation capacity of the heat supply unit for scheduling. The cogeneration unit reasonably participates in peak shaving and frequency modulation of the power grid, and plays an important role in energy conservation and emission reduction, clean energy consumption and economic dispatching.
Therefore, the cogeneration unit is required to adjust the power Generation load according to the demand of the heat supply load under the condition of ensuring the heat supply safety, and fully participate in the deep peak shaving of the power grid, and the power Generation load range which can be scheduled by an Automatic Generation Control (AGC) of the cogeneration unit under different heat supply loads also needs to be determined. At present, many researches in the aspect only calculate and deduce the relation between the power generation load and the main steam flow and the steam extraction flow, and the restriction factor of the minimum steam discharge of the low-pressure cylinder of the steam turbine is not fully considered; moreover, indirect measurement calculation or correction is required to be performed for online monitoring, calculation and judgment aiming at the problems that the measuring points are not installed on the steam turbines of a large cogeneration unit or the measurement is difficult and the precision is poor.
Disclosure of Invention
In order to solve the defects of the technology, the invention provides a method for calculating the peak shaving range of the cogeneration unit.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for calculating the peak regulation range of a cogeneration unit comprises the following steps:
according to the thermal characteristic data and the heat supply steam extraction flow of the cogeneration generator set, respectively fitting and determining an AGC maximum output load line of the generator set, a boiler minimum stable combustion output load line and a minimum power generation load line of the generator set under a heat supply working condition by taking the heat supply steam extraction flow of the generator set as an X axis and the power generation load of the generator set as a Y axis;
step two, the step one is combined to fit the determined boiler minimum stable combustion output load line and the unit minimum power generation load line under the heat supply working condition, and the unit AGC schedulable power generation load lower limit is solved;
step three, fitting the determined unit AGC maximum output load line, the boiler minimum stable combustion output load line and the unit minimum generating load line under the heat supply working condition according to the step one, combining the fitting equations, calculating a unit AGC adjustable generating load lower limit, a unit AGC adjustable generating load upper limit and a unit AGC adjustable generating load range under any heat supply steam extraction flow, and providing real-time data support for power grid deep peak shaving;
in the first step, the unit AGC maximum output load line is determined by fitting the maximum generating load of the unit under the rated heat consumption examination condition of the steam turbine and the generating load of the unit under the rated heat supply load condition, and the unit AGC maximum output load line is determined by fitting:
Y＝A1X+B1，
wherein X is the heat supply steam extraction flow of the unit, A1And B1Is a constant, and Y is the generating load of the unit;
the lowest stable combustion output load line of the boiler is determined by fitting of the lowest stable combustion test data of the boiler, and the lowest stable combustion output load line of the boiler is as follows:
Y＝A2X+B2，
wherein X is the heat supply steam extraction flow of the unit, A2And B2Is a constant, and Y is the generating load of the unit;
the method for determining the minimum power generation load line of the unit under the heat supply working condition comprises the following steps:
step (1), fitting and determining the minimum generating load of the unit under the rated heat supply condition by the maximum generating load of the unit under the rated heat consumption examining condition of the steam turbine, the generating load of the unit under the rated heat supply load condition, the rated heat consumption examining of the steam turbine and the minimum exhaust flow of the low pressure cylinder of the steam turbine under the rated heat supply load condition;
step (2), checking the maximum generating load of the unit under the working condition of rated heat consumption of the steam turbine, the generating load of the unit under the working condition of rated heat supply load, the rated generating load of the steam turbine and the minimum exhaust flow of the low pressure cylinder of the steam turbine under the working conditions of rated heat supply load and the minimum exhaust flow of the low pressure cylinder of the steam turbine by fitting, and determining the heat supply exhaust flow as X1The minimum power generation load of the unit under the heat supply working condition;
and (3) determining the minimum power generation load and the heat supply extraction steam flow of the unit as X according to the fitting under the rated heat supply working condition1And (3) fitting and determining a minimum generating load line of the unit under the heat supply working condition: y is A3X+B3，
Wherein X is the heat supply steam extraction flow of the unit, A3And B3Is constant and Y is the generating load of the unit.
Further, the method for calculating the peak shaving range of the cogeneration unit further comprises the following steps:
step four, determining the AGC schedulable power generation load range under the pure condensation working condition of the cogeneration unit and the AGC schedulable power generation load range under the heat supply working condition according to the unit AGC schedulable power generation load range obtained in the step three, wherein the specific method comprises the following steps:
the method for determining the AGC schedulable power generation load range under the pure condensation working condition of the cogeneration unit comprises the following steps:
step (1), according to a minimum stable combustion output load line of the boiler determined by fitting, when the heat supply steam extraction flow is zero, the generating load of the unit is the lower limit of the AGC schedulable generating load;
step (2), according to the maximum output load line of the AGC of the unit determined by fitting, when the heat supply steam extraction flow is zero, the generating load of the unit is the upper limit of the schedulable generating load of the AGC;
the method for determining the AGC schedulable power generation load range under the heat supply working condition of the cogeneration unit comprises the following steps:
step (1), when the heat supply steam extraction flow of the unit is smaller than the critical heat supply steam extraction flow and larger than zero, determining the generating load of the unit under different heat supply steam extraction flows, namely the lower limit of the AGC schedulable generating load according to the fitted lowest stable combustion output load line of the boiler;
step (2), when the heating steam extraction flow of the unit is larger than the critical heating steam extraction flow and smaller than the rated heating steam extraction flow, determining the generating load of the unit under different heating steam extraction flows according to the minimum generating load line of the unit under the fitted heating working condition, namely, the AGC schedulable generating load lower limit;
and (3) determining the maximum output load line of the AGC of the unit according to fitting, wherein the generating load of the unit is the upper limit of the schedulable generating load of the AGC when the heat supply extraction steam flow is larger than zero and smaller than the rated heat supply extraction steam flow.
Further, the method for determining the critical heat supply extraction steam flow of the minimum power generation load of the cogeneration unit under the heat supply working condition comprises the following steps:
step (1), simultaneously fitting the determined boiler minimum stable combustion output load line equation and the minimum generating load line equation of the unit under the heat supply working condition for calculation and solution;
and (2) determining the lower limit of the peak load regulation range of the unit according to the heat supply extraction flow value obtained by solving, wherein the condition lower than the heat supply extraction flow is limited by the minimum stable combustion output of the boiler, and the condition higher than the heat supply extraction flow is limited by the minimum exhaust steam quantity of a low-pressure cylinder of the steam turbine.
Further, the method for calculating the peak shaving range of the cogeneration unit further comprises the following steps:
and step five, carrying out soft measurement on the heat supply extraction steam flow of the cogeneration unit, monitoring the value in real time, calculating a fitting equation, carrying out soft measurement on the exhaust steam flow of the low-pressure cylinder of the steam turbine, judging boundary conditions required by calculation, monitoring the cooling flow of the low-pressure cylinder of the unit during deep peak shaving, and ensuring the safety of the unit.
Further, in the fifth step, the soft measurement method for the heat supply extraction flow rate of the steam turbine of the cogeneration unit comprises the following steps:
step (1), according to the thermal characteristic data of the cogeneration generator set, determining the heat supply steam extraction flow of the steam turbine by the maximum power generation load of the unit under the working condition of THA rated heat consumption examination of the steam turbine, the steam inlet steam flow of the steam turbine, the power generation load of the unit under the working condition of rated heat supply load, and multiple fitting:
Y＝K1X1+Q1X2，
wherein, X1For steam flow of the inlet steam of the steam turbine, X2For the generating load of the unit, K1And Q1And Y is the heat supply steam extraction flow of the steam turbine.
And (2) aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, correcting the heat supply steam extraction flow after fitting water and steam thermal property parameters in a typical operation range of a common heat supply unit.
Further, in the fifth step, the soft measurement method for the exhaust steam flow of the low-pressure cylinder of the steam turbine of the cogeneration unit comprises the following steps:
according to the thermal characteristic data of the cogeneration generator set, determining the steam discharge flow of the low-pressure cylinder of the steam turbine by the maximum power generation load of the unit and the steam inlet steam flow of the steam turbine under the working condition of THA rated heat consumption examination of the steam turbine, the power generation load of the unit under the working condition of rated heat load, the rated THA working condition of the steam turbine and the steam discharge flow of the low-pressure cylinder of the steam turbine under the working condition of rated heat load, the power generation load of the unit and the steam discharge flow of:
Y＝K2X1+Q2X2，
wherein, X1For steam flow of the inlet steam of the steam turbine, X2For the generating load of the unit, K2And Q2Is constant, and Y is the exhaust flow of the low-pressure cylinder of the steam turbine.
Aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, the heat supply steam extraction flow is corrected after water and steam thermal property parameters in a typical operation range of a common heat supply unit are adopted for fitting.
Further, the method for calculating the peak shaving range of the cogeneration unit further comprises the following steps:
step six, fitting a unit AGC maximum output load line, a boiler minimum stable combustion output load line and a unit minimum power generation load line under a heat supply working condition according to the unit AGC maximum output load line, the boiler minimum stable combustion output load line and the unit minimum power generation load line obtained in the step one, and drawing a heat supply extraction flow-unit power generation load curve graph by taking a heat supply extraction flow as a horizontal coordinate and taking a unit power generation load as a vertical coordinate;
and calculating and visually displaying the upper limit value, the lower limit value and the peak regulation range of the AGC schedulable power generation load of the unit under different heat supply steam extraction flows in real time by using the data of the heat supply steam extraction flow, the main steam flow, the unit power generation load, the low-pressure cylinder steam extraction flow and the like which are monitored on line, and displaying a calculation result list in real time.
According to the invention, curve fitting is carried out according to thermal characteristic data of a steam turbine of the cogeneration unit, correction is carried out according to the operation data of the unit under the actual working condition, the lower limit, the upper limit and the peak regulation range of the unit AGC (automatic gain control) adjustable power generation load under different heat supply extraction flows are calculated on line, basis and reference are provided for the operation of a power plant and the dispatching of a power grid, the operation is safe, simple and convenient and practical in engineering, and the requirements can be met; particularly, AGC schedulable lower limit of generating load of the unit under different heat supply extraction flows is obtained through online calculation, namely the minimum generating load can be scheduled, the lower limit of the load of the unit is expanded as much as possible, and the purpose of improving the deep peak regulation capacity of the power grid in the heat supply period is achieved; in addition, the soft measurement is carried out on the heat supply extraction flow and the exhaust flow of the low-pressure cylinder of the steam turbine, so that the problems that the measuring points are not installed on the steam turbines of a large cogeneration unit or the measuring is difficult and poor in precision are solved.
Drawings
Fig. 1 is a flow chart of a method for calculating a peak shaving range of a cogeneration unit in accordance with the present invention.
Fig. 2 is a graph of AGC schedulable power generation load range under different heat supply extraction steam flow rates of the cogeneration unit.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The method for calculating the peak shaving range of the cogeneration unit shown in fig. 1 comprises the following steps:
1) taking the thermal characteristic data of a certain cogeneration unit as an example, the steam turbine of the unit is a subcritical, intermediate reheating, two-cylinder two-steam-exhaust and heating steam-extraction type steam turbine, and the rated heat supply working condition data is shown in table 1:
TABLE 1 turbine rating heat supply condition data
Figure GDA0002767552270000061
Figure GDA0002767552270000071
The thermal characteristic data of the cogeneration generator set are collated as shown in table 2:
TABLE 2 Cogeneration of thermal characteristics data of the generator set
Figure GDA0002767552270000072
2) According to the thermal characteristic data and the heat supply extraction flow of the cogeneration generator set, a unit AGC maximum output load line is determined by fitting the maximum power generation load 300MW of the unit under the THA (rated heat consumption examination condition) of the turbine and the power generation load 235MW of the unit under the 400t/h rated heat supply load, as shown by an AB line shown in FIG. 2:
Y＝A1X+B1，
wherein X is the heat supply steam extraction flow of the unit, A1And B1Is a constant, and Y is the generating load of the unit;
as shown in FIG. 2, from point A (0,300), the maximum power load operating point, main steam flow 872.6 t/h; point B (400,235), rated heating load operating point, main steam flow 872.6t/h, because when the heating extraction flow is constant, the generator power and the steam turbine steam intake can be approximately regarded as linear relation, and the least square fitting can be used for obtaining:
Y＝-0.1625X+300；A1＝-0.1625，B1＝300。
3) according to the thermal characteristic data and the heat supply extraction steam flow of the cogeneration generator set, the lowest stable combustion test data of the boiler is used, the main steam flow is 35% BMCR (maximum continuous output 1025t/h) when the unit is at the lowest stable combustion, the working condition corresponds to the load 120MW under the working condition of generating load 40% THA of the unit, and the lowest stable combustion output load line of the boiler is determined by fitting, such as a DE line shown in figure 2:
Y＝A2X+B2，
wherein X is the heat supply steam extraction flow of the unit, A2And B2Is a constant, and Y is the generating load of the unit;
referring to FIG. 2, point E (0,120) is the lowest steady combustion power generation load operating point, main steam flow 349.5 t/h; and point D (165,93.2), a maximum heat supply steam extraction flow working point corresponding to the minimum power generation load of the unit when the boiler is at the lowest stable combustion, namely critical heat supply steam extraction flow, is calculated by the following method steps.
Y＝-0.1625X+120；A2＝-0.1625，B2＝120。
4) According to the thermal characteristic data of the cogeneration generator set, the maximum power generation load of the unit is 300MW under the rated heat consumption examination condition of a turbine THA, the power generation load of the unit is 235MW under the rated heat supply load of 400t/h, the turbine THA is 75%, 50%, 40% and 30% THA, and the exhaust steam flow of a low-pressure cylinder of the turbine under the rated heat supply condition is 559.944t/h, 425.829t/h, 301.709t/h, 251.518t/h, 192.824t/h and 228.104t/h respectively, the exhaust steam flow of the low-pressure cylinder of the turbine under the maximum heat supply condition is 122.946t/h and the minimum exhaust steam flow of the low-pressure cylinder of the turbine is 90t/h respectively, and the minimum power generation load of the unit under the rated heat supply condition is determined by least square fitting according to the sum of the main steam flow, the heat supply exhaust steam flow and the exhaust.
Y＝1.9391X-345.1719，
Wherein X is the sum of the heating steam extraction and the low-pressure cylinder steam exhaust, and Y is the main steam flow.
When X is 490t/h, the main steam flow Y is 605t/h, corresponding to a power generation load of 208MW in terms of main steam flow to load ratio, as shown at point (400,208) in FIG. 2C.
5) According to the thermal characteristic data of the cogeneration generator set, the minimum power generation load of the set when the heat supply steam extraction flow is X1 is determined by fitting the heat supply steam extraction flow of 300t/h, the maximum power generation load of the set 300MW under the THA rated heat consumption checking condition of the steam turbine, the power generation load of the set 235MW under the 400t/h rated heat supply load, the rated power generation load of the steam turbine, the exhaust flow of the low-pressure cylinder of the steam turbine of 559.944t/h and 228.104t/h and the minimum exhaust flow of the low-pressure cylinder of the steam turbine of 90t/h under the 400t/h rated heat supply load condition.
Y＝208-0.1625X，
Wherein, X is the heat supply steam extraction flow, and Y is the generating load of the unit.
When X is 300t/h, the unit power generation load Y is 159.25MW, as shown in FIG. 2X1 point (300,159.25).
6) According to the minimum generating load C point (400,208) of the set when the rated heating extraction steam flow is determined to be 400t/h and the minimum generating load X1 point (300,159.25) of the set when the heating extraction steam flow is 300t/h through fitting, the minimum generating load line of the set under the heating working condition is determined through fitting, and is shown as a CD line in figure 2:
Y＝A3X+B3，
wherein X is the heat supply steam extraction flow of the unit, A3And B3Is constant and Y is the generating load of the unit.
Y＝0.4875X+13；A3＝0.4875，B3＝13。
7) And according to the steps 3) and 6), respectively fitting the determined boiler minimum stable combustion output load line DE and the unit minimum power generation load line CD under the heat supply working condition, and solving the unit AGC schedulable power generation load lower limit, namely the CDE broken line, by combining the fitting equations.
8) According to the steps of 2), 3) and 6), respectively fitting the determined unit AGC maximum output load line AB, the boiler minimum stable combustion output load line DE and the unit minimum power generation load line CD under the heat supply working condition, and calculating a unit AGC adjustable power generation load lower limit CDE broken line, an AGC adjustable power generation load upper limit AB line and an AGC adjustable power generation load range under any heat supply steam extraction flow, namely the difference between the upper limit value and the lower limit value, so as to provide real-time data support for the depth peak regulation of the power grid.
9) According to the obtained simultaneous fitting equation, determining the AGC schedulable power generation load range under the pure condensation working condition of the cogeneration unit and the AGC schedulable power generation load range under the heat supply working condition, comprising the following steps:
(1) according to the minimum stable combustion output load line DE of the boiler determined by fitting, when the heat supply steam extraction flow is zero, the generating load of the unit is the lower limit of the AGC schedulable generating load, and the unit is 120 MW;
(2) according to the maximum output load line AB of the unit AGC determined by fitting, when the heat supply extraction flow is zero, the generating load of the unit is the upper limit of the schedulable generating load of the AGC, and the unit is 300 MW;
(3) when the heat supply steam extraction flow of the unit is smaller than the critical heat supply steam extraction flow 165t/h and larger than zero, determining the generating load of the unit under different heat supply steam extraction flows, namely the lower limit of the AGC (automatic gain control) schedulable generating load according to the fitted lowest stable combustion output load line DE of the boiler;
(4) when the heat supply steam extraction flow of the unit is larger than the critical heat supply steam extraction flow 165t/h and smaller than the rated heat supply steam extraction flow 400t/h, determining the generating load of the unit under different heat supply steam extraction flows, namely the AGC schedulable generating load lower limit according to the minimum generating load line CD of the unit under the fitted heat supply working condition;
(5) and according to the maximum output load line of the AGC of the unit determined by fitting, when the heat supply extraction flow is more than zero and less than the rated heat supply extraction flow by 400t/h, the generating load of the unit is the upper limit of the schedulable generating load of the AGC.
The method for determining the critical heat supply extraction steam flow of the minimum power generation load of the cogeneration unit under the heat supply working condition comprises the following steps:
(1) calculating and solving a DE equation of the boiler minimum stable combustion output load line determined by simultaneous fitting and a CD equation of the unit minimum power generation load line under the heat supply working condition;
Y＝0.4875X+13；Y＝-0.1625X+120；
solving a linear equation of two to obtain X of 165t/h and Y of 93.2MW, as shown in a point D (165,93.2) in FIG. 2;
(2) and determining the lower limit of the peak load regulation range of the unit according to the heat supply extraction flow value obtained by solving, wherein the condition lower than the heat supply extraction flow is limited by the lowest stable combustion output of the boiler, and the condition higher than the heat supply extraction flow is limited by the minimum steam discharge of a low-pressure cylinder of the steam turbine.
10) The method comprises the steps of carrying out soft measurement on the heat supply extraction flow of the cogeneration unit, monitoring the value in real time, calculating a fitting equation, carrying out soft measurement on the exhaust flow of the low-pressure cylinder of the steam turbine, judging boundary conditions required by calculation, monitoring the cooling flow of the low-pressure cylinder of the unit during deep peak regulation, and ensuring the safety of the unit.
The soft measurement method for the heat supply extraction flow of the steam turbine of the cogeneration unit comprises the following steps:
(1) according to the thermal characteristic data of the cogeneration generator set, the maximum generating load of the generator set is 300MW under the rated heat consumption examination condition of the turbine THA, the steam inlet flow of the turbine is 872.6t/h, the generating load of the generator set is 235t/h under the rated heat supply load is 400t/h, the generating load of the generator set and the main steam flow, and the heat supply steam extraction flow of the turbine is determined by multivariate fitting:
Y＝K1X1+Q1X2，
wherein, X1Is the main steam flow, X2For the generating load of the unit, K1And Q1Is constant, Y is the heat supply extraction flow of the steam turbine;
Y＝2.1157X1-6.1538X2；K1＝2.1157，Q1＝-6.1538。
(2) aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, heat supply steam extraction flow is corrected after water and steam thermal property parameters in a typical operation range of a common heat supply unit are adopted for fitting:
Y＝(2.1157X1-6.1538X2)[0.207(Ph0-Ph)]；
wherein, Ph0For rated heat supply extraction pressure, PhFor supplying heat and extracting steam pressure.
The soft measurement method of the exhaust steam flow of the low-pressure cylinder of the steam turbine of the cogeneration unit comprises the following steps:
(1) according to the thermal characteristic data of the cogeneration generator set, the maximum generating load of the generator set is 300MW and the steam inlet flow of the turbine is 872.6t/h under the rated heat consumption examination working condition of the turbine THA, the generating load of the generator set is 235t/h under the rated heat load working condition of 400t/h, the steam exhaust flow of the low-pressure cylinder of the turbine is 559.944t/h and 228.104t/h under the rated THA working condition of the turbine and the rated heat load working condition, and the steam exhaust flow of the low-pressure cylinder of the turbine is determined by multivariate fitting according to the generating load of the generator set and the main steam flow:
Y＝K2X1+Q2X2，
wherein, X1Is the main steam flow, X2For the generating load of the unit, K2And Q2Is constant, Y is the exhaust flow of the low-pressure cylinder of the steam turbine,
Y＝559.944-1.7552X1+5.1052X2；K1＝-1.7552，Q1＝5.1052。
(2) aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, heat supply steam extraction flow is corrected after water and steam thermal property parameters in a typical operation range of a common heat supply unit are adopted for fitting:
Y＝559.944-(1.7552X1-5.1052X2)/[0.207(Ph0-Ph)]。
11) according to the fitting equation obtained in the steps 2), 3) and 6), a curve chart of the heat supply steam extraction flow and the unit power generation load is drawn by taking the heat supply steam extraction flow as an abscissa and the unit power generation load as an ordinate, as shown in figure 2.
12) The method comprises the steps of calculating the heat supply extraction flow and the low-pressure cylinder extraction flow of a unit in real time, calculating, correcting and visually displaying the upper limit value, the lower limit value and the peak regulation range of the unit AGC (automatic gain control) adjustable power generation load under different heat supply extraction flows by utilizing data such as the heat supply extraction flow, the main steam flow, the unit power generation load, the low-pressure cylinder extraction flow and the extraction pressure which are monitored on line, and displaying a calculation result list as shown in a table 3.
TABLE 3 AGC schedulable generating load peak regulation range of unit under different heat supply steam extraction flow
Figure GDA0002767552270000121
The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make variations, modifications, additions or substitutions within the technical scope of the present invention.

Claims (7)

1. A method for calculating the peak regulation range of a cogeneration unit is characterized by comprising the following steps:
according to the thermal characteristic data and the heat supply steam extraction flow of the cogeneration generator set, respectively fitting and determining an AGC maximum output load line of the generator set, a boiler minimum stable combustion output load line and a minimum power generation load line of the generator set under a heat supply working condition by taking the heat supply steam extraction flow of the generator set as an X axis and the power generation load of the generator set as a Y axis;
step two, the step one is combined to fit the determined boiler minimum stable combustion output load line and the unit minimum power generation load line under the heat supply working condition, and the unit AGC schedulable power generation load lower limit is solved;
step three, fitting the determined unit AGC maximum output load line, the boiler minimum stable combustion output load line and the unit minimum generating load line under the heat supply working condition according to the step one, combining the fitting equations, calculating a unit AGC adjustable generating load lower limit, a unit AGC adjustable generating load upper limit and a unit AGC adjustable generating load range under any heat supply steam extraction flow, and providing real-time data support for power grid deep peak shaving;
in the first step, the unit AGC maximum output load line is determined by fitting the maximum generating load of the unit under the rated heat consumption examination condition of the steam turbine and the generating load of the unit under the rated heat supply load condition, and the unit AGC maximum output load line is determined by fitting:
Y＝A1X+B1，
wherein X is the heat supply steam extraction flow of the unit, A1And B1Is a constant, and Y is the generating load of the unit;
the lowest stable combustion output load line of the boiler is determined by fitting of the lowest stable combustion test data of the boiler, and the lowest stable combustion output load line of the boiler is as follows:
Y＝A2X+B2，
wherein X is the heat supply steam extraction flow of the unit, A2And B2Is a constant, and Y is the generating load of the unit;
the method for determining the minimum power generation load line of the unit under the heat supply working condition comprises the following steps:
step (1), fitting and determining the minimum generating load of the unit under the rated heat supply condition by the maximum generating load of the unit under the rated heat consumption examining condition of the steam turbine, the generating load of the unit under the rated heat supply load condition, the rated heat consumption examining of the steam turbine and the minimum exhaust flow of the low pressure cylinder of the steam turbine under the rated heat supply load condition;
step (2), checking the maximum generating load of the unit under the working condition of rated heat consumption of the steam turbine, the generating load of the unit under the working condition of rated heat supply load, the rated generating load of the steam turbine and the minimum exhaust flow of the low pressure cylinder of the steam turbine under the working conditions of rated heat supply load and the minimum exhaust flow of the low pressure cylinder of the steam turbine by fitting, and determining the heat supply exhaust flow as X1Machine under heat supply working conditionGroup minimum power generation load;
and (3) determining the minimum power generation load and the heat supply extraction steam flow of the unit as X according to the fitting under the rated heat supply working condition1And (3) fitting and determining a minimum generating load line of the unit under the heat supply working condition: y is A3X+B3，
Wherein X is the heat supply steam extraction flow of the unit, A3And B3Is constant and Y is the generating load of the unit.
2. The method for calculating the peak shaving range of a cogeneration unit according to claim 1, characterized in that: the method for calculating the peak regulation range of the cogeneration unit further comprises the following steps:
step four, determining the AGC schedulable power generation load range under the pure condensation working condition of the cogeneration unit and the AGC schedulable power generation load range under the heat supply working condition according to the unit AGC schedulable power generation load range obtained in the step three, wherein the specific method comprises the following steps:
the method for determining the AGC schedulable power generation load range under the pure condensation working condition of the cogeneration unit comprises the following steps:
step (1), according to a minimum stable combustion output load line of the boiler determined by fitting, when the heat supply steam extraction flow is zero, the generating load of the unit is the lower limit of the AGC schedulable generating load;
step (2), according to the maximum output load line of the AGC of the unit determined by fitting, when the heat supply steam extraction flow is zero, the generating load of the unit is the upper limit of the schedulable generating load of the AGC;
the method for determining the AGC schedulable power generation load range under the heat supply working condition of the cogeneration unit comprises the following steps:
step (1), when the heat supply steam extraction flow of the unit is smaller than the critical heat supply steam extraction flow and larger than zero, determining the generating load of the unit under different heat supply steam extraction flows, namely the lower limit of the AGC schedulable generating load according to the fitted lowest stable combustion output load line of the boiler;
step (2), when the heating steam extraction flow of the unit is larger than the critical heating steam extraction flow and smaller than the rated heating steam extraction flow, determining the generating load of the unit under different heating steam extraction flows according to the minimum generating load line of the unit under the fitted heating working condition, namely, the AGC schedulable generating load lower limit;
and (3) determining the maximum output load line of the AGC of the unit according to fitting, wherein the generating load of the unit is the upper limit of the schedulable generating load of the AGC when the heat supply extraction steam flow is larger than zero and smaller than the rated heat supply extraction steam flow.
3. The method for calculating the peak shaving range of a cogeneration unit according to claim 2, characterized in that: the method for determining the critical heat supply extraction steam flow of the minimum power generation load of the cogeneration unit under the heat supply working condition comprises the following steps:
step (1), simultaneously fitting the determined boiler minimum stable combustion output load line equation and the minimum generating load line equation of the unit under the heat supply working condition for calculation and solution;
and (2) determining the lower limit of the peak load regulation range of the unit according to the heat supply extraction flow value obtained by solving, wherein the condition lower than the heat supply extraction flow is limited by the minimum stable combustion output of the boiler, and the condition higher than the heat supply extraction flow is limited by the minimum exhaust steam quantity of a low-pressure cylinder of the steam turbine.
4. The method for calculating the peak shaving range of a cogeneration unit according to claim 3, wherein: the method for calculating the peak regulation range of the cogeneration unit further comprises the following steps:
and step five, carrying out soft measurement on the heat supply extraction steam flow of the cogeneration unit, monitoring the value in real time, calculating a fitting equation, carrying out soft measurement on the exhaust steam flow of the low-pressure cylinder of the steam turbine, judging boundary conditions required by calculation, monitoring the cooling flow of the low-pressure cylinder of the unit during deep peak shaving, and ensuring the safety of the unit.
5. The method for calculating the peak shaving range of a cogeneration unit according to claim 4, wherein: in the fifth step, the soft measurement method for the heat supply extraction flow of the steam turbine of the cogeneration unit comprises the following steps:
step (1), according to the thermal characteristic data of the cogeneration generator set, determining the heat supply steam extraction flow of the steam turbine by the maximum power generation load of the unit under the working condition of THA rated heat consumption examination of the steam turbine, the steam inlet steam flow of the steam turbine, the power generation load of the unit under the working condition of rated heat supply load, and multiple fitting:
Y＝K1X1+Q1X2，
wherein, X1For steam flow of the inlet steam of the steam turbine, X2For the generating load of the unit, K1And Q1Is constant, Y is the heat supply extraction flow of the steam turbine;
and (2) aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, correcting the heat supply steam extraction flow after fitting water and steam thermal property parameters in a typical operation range of a common heat supply unit.
6. The method for calculating the peak shaving range of a cogeneration unit according to claim 5, wherein: in the fifth step, the soft measurement method for the exhaust steam flow of the low-pressure cylinder of the steam turbine of the cogeneration unit comprises the following steps:
according to the thermal characteristic data of the cogeneration generator set, determining the steam discharge flow of the low-pressure cylinder of the steam turbine by the maximum power generation load of the unit and the steam inlet steam flow of the steam turbine under the working condition of THA rated heat consumption examination of the steam turbine, the power generation load of the unit under the working condition of rated heat load, the rated THA working condition of the steam turbine and the steam discharge flow of the low-pressure cylinder of the steam turbine under the working condition of rated heat load, the power generation load of the unit and the steam discharge flow of:
Y＝K2X1+Q2X2，
wherein, X1For steam flow of the inlet steam of the steam turbine, X2For the generating load of the unit, K2And Q2Is constant, Y is the exhaust flow of the low-pressure cylinder of the steam turbine;
aiming at different steam extraction enthalpies under different heat supply steam extraction pressures, the heat supply steam extraction flow is corrected after water and steam thermal property parameters in a typical operation range of a common heat supply unit are adopted for fitting.
7. The method for calculating the peak shaving range of the cogeneration unit according to claim 6, wherein: the method for calculating the peak regulation range of the cogeneration unit further comprises the following steps:
step six, fitting a unit AGC maximum output load line, a boiler minimum stable combustion output load line and a unit minimum power generation load line under a heat supply working condition according to the unit AGC maximum output load line, the boiler minimum stable combustion output load line and the unit minimum power generation load line obtained in the step one, and drawing a heat supply extraction flow-unit power generation load curve graph by taking a heat supply extraction flow as a horizontal coordinate and taking a unit power generation load as a vertical coordinate;
and calculating and visually displaying the upper limit value, the lower limit value and the peak regulation range of the AGC schedulable power generation load of the unit under different heat supply steam extraction flows in real time by using the data of the heat supply steam extraction flow, the main steam flow, the unit power generation load, the low-pressure cylinder steam extraction flow and the like which are monitored on line, and displaying a calculation result list in real time.
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