An optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit

Abstract

The present invention relates to an optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit, including: constructing the electric-heat operation domain and the zero-output operation line graph of the low-pressure cylinder of the condensing extraction unit under the condensing extraction condition, determining the energy consumption of the condensing extraction unit under the condensing extraction condition and the energy consumption of the zero-output condition of the low-pressure cylinder, judging the "conjugate zone" where the two conditions can supply the same heat load, comparing the operation benefits of the condensing extraction condition and the zero-output condition of the low-pressure cylinder within the "conjugate zone", calculating the benefit difference and peak shaving compensation benefit between the condensing extraction condition and the zero-output condition of the low-pressure cylinder, and constructing a comparison graph of peak shaving compensation and benefit difference for the zero-output condition of the low-pressure cylinder of the condensing extraction unit; finally, constructing a judgment rule for whether the condensing extraction unit changes from the condensing extraction condition to the zero-output condition of the low-pressure cylinder, and determining whether the condensing extraction unit changes to the zero-output condition of the low-pressure cylinder, which has the advantages of simplifying the operation process and intuitively judging the adjustment rule of the optimized operation method for zero output of the low-pressure cylinder of the condensing extraction unit.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation, and particularly to an optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit. Background Art

[0002] The zero output technology of the low-pressure cylinder has received extensive attention from domestic and foreign scholars because it can not only achieve thermal power decoupling, but also has advantages such as flexible switching, low transformation cost, and low maintenance cost.

[0003] After the low-pressure cylinder is removed, the heat supply capacity of the unit increases and the load rate decreases. At the same time, there will also be certain limiting conditions compared with the condensing extraction condition, such as a smaller adjustment range of the heat supply quantity. Considering the operation costs and benefits of the zero output condition of the low-pressure cylinder of the condensing extraction unit and the condensing extraction condition, it is of guiding significance for adjusting the unit condition. However, the existing optimization methods are relatively complex. For example, a method for determining the minimum technical output characteristics under the zero output operation mode of the low-pressure cylinder of a condensing extraction heat supply unit disclosed in CN114922706A adjusts the heat extraction steam flow of the heat supply unit according to this characteristic relationship, adjusts the minimum technical output of the heat supply unit, and then improves the peak shaving operation ability under the zero output mode of the low-pressure cylinder of the heat supply unit. However, it is impossible to intuitively judge the adjustment rules of the optimized operation method for the zero output of the low-pressure cylinder of the condensing extraction unit. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the defects in the prior art, so as to provide an optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit includes:

[0007] S1: Perform off-design calculations for the condensing extraction condition and the zero output condition of the low-pressure cylinder of the condensing extraction unit, and construct the electrothermal operation domain of the condensing extraction condition and the zero output operation line diagram of the low-pressure cylinder of the condensing extraction unit;

[0008] S2: According to the electrothermal operation domain of the condensing extraction condition and the zero output operation line diagram of the low-pressure cylinder of the condensing extraction unit, and by using the method of mathematical fitting, determine the energy consumption of the condensing extraction condition and the energy consumption of the zero output condition of the low-pressure cylinder of the condensing extraction unit;

[0009] S3: According to the electrothermal operation domain of the condensing extraction condition and the zero output operation line diagram of the low-pressure cylinder of the condensing extraction unit, judge the "conjugate region" where the condensing extraction condition and the zero output condition of the low-pressure cylinder of the condensing extraction unit can supply the same heat load;

[0010] S4: Compare the operating benefits of the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode according to the energy consumption of the extraction-condensing unit in the "conjugate area" under the extraction-condensing operation mode and the energy consumption under the zero output of the low-pressure cylinder operation mode, and calculate the benefit difference between the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode;

[0011] S5: Account for the peak shaving compensation benefits of the zero output of the low-pressure cylinder operation mode;

[0012] S6: Construct a comparison chart of the peak shaving compensation and benefit difference for the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit based on the peak shaving compensation benefits of the zero output of the low-pressure cylinder operation mode and the benefit difference;

[0013] S7: Determine whether the extraction-condensing unit changes to the zero output of the low-pressure cylinder operation mode in combination with the comparison chart of the peak shaving compensation and benefit difference for the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit, so as to construct a judgment rule on whether the extraction-condensing unit changes from the extraction-condensing operation mode to the zero output of the low-pressure cylinder operation mode.

[0014] Preferably, the construction of the extraction-condensing electric-heat operation domain and the zero output of the low-pressure cylinder operation line chart of the extraction-condensing unit specifically includes:

[0015] Construct a coordinate system with the heat load of the extraction-condensing unit as the abscissa and the electric load of the extraction-condensing unit as the ordinate;

[0016] Determine the operation boundary of the extraction-condensing unit in the coordinate system according to the selected operation limit conditions of the extraction-condensing unit;

[0017] Select several known and discretely distributed reference operating conditions to calculate the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit, and determine the extraction-condensing operation domain limit line and the zero output of the low-pressure cylinder operation line.

[0018] Preferably, the calculation of the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit specifically includes:

[0019] Use the Flügel formula to determine the corresponding extraction steam pressure of the unit under the extraction-condensing operation mode of the extraction-condensing unit, and determine the mutual relationship between the electric load and the heat load under the extraction-condensing operation mode. Then, determine the extraction-condensing operation domain limit line according to the mutual relationship between the electric load and the heat load under the extraction-condensing operation mode;

[0020] Use the Flügel formula to determine the corresponding extraction steam pressure of the unit under the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit, and determine the mutual relationship between the electric load and the heat load under the zero output of the low-pressure cylinder operation mode. Then, determine the zero output of the low-pressure cylinder operation line according to the mutual relationship between the electric load and the heat load under the zero output of the low-pressure cylinder operation mode.

[0021] Preferably, determining the extraction-condensing operation domain limit line according to the mutual relationship between the electric load and the heat load under the extraction-condensing operation mode specifically includes:

[0022] According to the maximum extraction steam volume of the unit, within the range from zero to the maximum extraction steam volume, several groups of the extraction steam volume are selected at equal intervals, and the corresponding main steam volume, electric load, and heat load are calculated based on the mutual relationship between the electric load and the heat load under the extraction-condensing condition, and the first data group of the main steam volume, the electric load, and the heat load is generated; according to the range between the minimum main steam volume and the maximum main steam volume of the unit, several groups of the main steam volume are selected at equal intervals, and the second data group of the main steam volume, the electric load, and the heat load is calculated based on the mutual relationship between the electric load and the heat load under the extraction-condensing condition; the operation domain of the extraction-condensing condition is determined according to the first data group and the second data group;

[0023] The zero-load operation line of the low-pressure cylinder is determined according to the mutual relationship between the electric load and the heat load under the zero-load condition of the low-pressure cylinder, which specifically includes:

[0024] According to the range between the minimum main steam volume and the maximum main steam volume of the unit, several groups of the main steam volume are selected at equal intervals, and the third data group of the main steam volume, the electric load, and the heat load is calculated based on the mutual relationship between the electric load and the heat load under the zero-load condition of the low-pressure cylinder, and the zero-load operation line of the low-pressure cylinder is generated.

[0025] Preferably, in the step of determining the energy consumption of the extraction-condensing unit under the extraction-condensing condition and the energy consumption under the zero-load condition of the low-pressure cylinder, the following formula is used to calculate the total operation benefit of the unit under the extraction-condensing condition and the zero-load condition of the low-pressure cylinder:

[0026] W ope =E e ×P e +E q ×Q h -B tot ×C0

[0027] In the formula: W ope is the operation benefit of the unit, with the unit of CNY·h -1 ; E e is the reference electricity price, with the unit of CNY·(MW·h) -1 ; P e is the electric load of the unit, with the unit of MW; E q is the reference heat price, with the unit of CNY·GJ -1 ; Q h is the heat load of the unit, with the unit of GJ·h -1 ; C0 is the reference coal price, with the unit of CNY·t -1 ; B tot is the total coal consumption of the unit, with the unit of t·h -1 .

[0028] Preferably, the benefit difference is calculated using the following formula:

[0029] ΔW = W ope1 - W ope2

[0030] where: ΔW is the difference in total operating income between the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode, with the unit of CNY·h -1 ; W ope1 and W ope2 respectively represent the total operating benefit of the unit under the extraction-condensing operation mode of the extraction-condensing unit and the total operating benefit of the unit under the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit.

[0031] Preferably, the peak shaving compensation income of the zero output of the low-pressure cylinder operation mode is calculated, including calculating the peak shaving compensation income of the unit using the following formula:

[0032]

[0033] where: W p-s is the peak shaving income of the unit / CNY·h -1 , P e0 is the unit capacity / MW, R k is the upper limit of the k-th gear peak shaving load rate, R is the unit load rate, S k is the k-th gear peak shaving compensation quotation / CNY·(MW·h) -1 .

[0034] Preferably, the judgment rule for whether the extraction-condensing unit changes from the extraction-condensing operation mode to the zero output of the low-pressure cylinder operation mode is specifically:

[0035] When the sum of the benefit difference and the peak shaving compensation income of the unit is not greater than 0, maintain the extraction-condensing heating mode of the extraction-condensing unit; when the sum of the benefit difference and the peak shaving compensation income of the unit is greater than 0, switch to the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit.

[0036] Preferably, in the process of constructing the extraction-condensing electric-heat operation domain and the zero output of the low-pressure cylinder operation line diagram of the extraction-condensing unit and determining the energy consumption of the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode of the extraction-condensing unit, the least squares polynomial fitting method is used for mathematical fitting.

[0037] Preferably, according to the selected operation limit conditions of the extraction-condensing unit, the operation boundary of the extraction-condensing unit is determined in the coordinate system, specifically including:

[0038] According to the limit condition that the main steam flow is less than the maximum continuous evaporation of the boiler, the first limit boundary is determined;

[0039] According to the limit condition that the low-pressure cylinder inlet steam flow is greater than the minimum condensing flow, the second limit boundary is determined;

[0040] According to the limitation that the unit load is greater than the load under the stable combustion condition of the boiler, the third limitation boundary is determined.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows: An optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit provided in the above technical solution, by constructing an electric-heat operation domain of the condensing extraction unit under the condensing extraction condition and a line graph of zero output operation of the low-pressure cylinder of the condensing extraction unit, and determining the energy consumption of the condensing extraction unit under the condensing extraction condition and the energy consumption of the zero output operation of the low-pressure cylinder of the condensing extraction unit, and then calculating and comparing the operation benefits and benefit differences between the condensing extraction unit and the zero output unit of the low-pressure cylinder, calculating the peak shaving compensation income of the zero output unit of the low-pressure cylinder, and generating a comparison graph of peak shaving compensation and benefit differences, that is, mathematically fitting the electric-heat operation domain of the condensing extraction unit under the condensing extraction condition and the line of zero output operation of the low-pressure cylinder of the condensing extraction unit, which simplifies the calculation process of the income of variable-condition electric and heat loads; at the same time, the coal consumption of the unit is also mathematically fitted, which simplifies the calculation process of the variable-condition operation cost. In addition, through the comparison graph of peak shaving compensation and benefit differences of the zero output unit of the low-pressure cylinder and the judgment rule of whether the condensing extraction unit changes from the condensing extraction condition to zero output operation of the low-pressure cylinder, it can be intuitively judged whether the unit needs to change to zero output operation of the low-pressure cylinder, which is beneficial to improving the operation benefit of the condensing extraction unit. Description of the Drawings

[0042] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0043] Figure 1 It is the electric-heat operation domain of the condensing extraction unit of the present invention and the line graph of zero output operation of the low-pressure cylinder of the condensing extraction unit.

[0044] Figure 2 It is the comparison graph of peak shaving compensation and benefit differences of the zero output operation condition of the low-pressure cylinder of the condensing extraction unit. Detailed Embodiments

[0045] The following will clearly and completely describe the technical solutions of the present invention with reference to the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0046] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance.

[0047] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0048] The embodiment of the present invention provides an optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit, including: the first step is to perform off-design calculations for the condensing extraction condition and the zero output condition of the low-pressure cylinder of the condensing extraction unit, and construct the off-design electrothermal operation domain of the condensing extraction unit and the zero output operation line diagram of the low-pressure cylinder; the second step is to determine the energy consumption of the condensing extraction condition and the energy consumption of the zero output condition of the low-pressure cylinder of the condensing extraction unit according to the off-design electrothermal operation domain of the condensing extraction unit and the zero output operation line diagram of the low-pressure cylinder, and by using the method of mathematical fitting; the third step is to judge the "conjugate area" where the condensing extraction condition and the zero output condition of the low-pressure cylinder of the condensing extraction unit can supply the same heat load according to the off-design electrothermal operation domain of the condensing extraction unit and the zero output operation line diagram of the low-pressure cylinder; the fourth step is to compare the operation benefits of the condensing extraction condition and the zero output condition of the low-pressure cylinder according to the energy consumption of the condensing extraction condition and the energy consumption of the zero output condition of the low-pressure cylinder in the "conjugate area", and calculate the benefit difference between the condensing extraction condition and the zero output condition of the low-pressure cylinder; the fifth step is to calculate the peak shaving compensation benefit of the zero output condition of the low-pressure cylinder; the sixth step is to construct a comparison diagram of the peak shaving compensation and the benefit difference for the zero output condition of the low-pressure cylinder of the condensing extraction unit according to the peak shaving compensation benefit and the benefit difference of the zero output condition of the low-pressure cylinder; the seventh step is to determine whether the condensing extraction unit changes to the zero output operation of the low-pressure cylinder in combination with the comparison diagram of the peak shaving compensation and the benefit difference for the zero output condition of the low-pressure cylinder of the condensing extraction unit, so as to construct a judgment rule on whether the condensing extraction unit changes from the condensing extraction condition to the zero output condition of the low-pressure cylinder.

[0049] In the above technical solution, by mathematically fitting the electro-thermal operation domain of the extraction-condensing unit under the extraction-condensing condition and the zero output operation line of the low-pressure cylinder of the extraction-condensing unit, the calculation process of the power and heat load benefits under variable operating conditions is simplified; at the same time, the coal consumption of the unit is also mathematically fitted, simplifying the calculation process of the variable operating cost; in addition, through the peak shaving compensation and benefit difference comparison chart of the zero output unit of the low-pressure cylinder and the judgment rule of whether the extraction-condensing unit changes to the zero output operation of the low-pressure cylinder, it can be intuitively judged whether the unit needs to change to the zero output operation of the low-pressure cylinder, which is beneficial to improving the operation benefit of the zero output of the low-pressure cylinder of the extraction-condensing unit.

[0050] Specifically, constructing the electro-thermal operation domain of the extraction-condensing unit and the zero output operation line diagram of the low-pressure cylinder specifically includes the following:

[0051] Step 1: Construct a coordinate system with the heat load of the extraction-condensing unit as the abscissa and the electric load of the extraction-condensing unit as the ordinate;

[0052] Step 2: According to the selected operation restriction conditions of the extraction-condensing unit, determine the operation boundary of the extraction-condensing unit in the coordinate system. As Figure 1 shown, in this step, according to the restriction condition that the main steam flow is less than the maximum continuous evaporation capacity of the boiler, determine the first restriction boundary AB; according to the restriction condition that the inlet steam flow of the low-pressure cylinder is greater than the minimum condensing flow, determine the second restriction boundary BC; according to the restriction condition that the unit load is greater than the load under the stable combustion condition of the boiler, determine the third restriction boundary CD;

[0053] Step 3: Select several known and discretely distributed reference operating conditions to calculate the extraction-condensing condition and the zero output condition of the low-pressure cylinder of the extraction-condensing unit, and determine the operation domain limit line and the zero output operation line of the low-pressure cylinder under the extraction-condensing condition. Among them, the parameters selected for the discretely distributed reference operating conditions can be from the heat balance diagram or on-site test data.

[0054] Furthermore, calculating the extraction-condensing condition and the zero output condition of the low-pressure cylinder of the extraction-condensing unit specifically includes, that is, the above Step 3 specifically includes:

[0055] Divide the steam turbine into two parts composed of the governing stage to the extraction port and the extraction port to the condenser, and then use the Flügel formula to determine the extraction steam pressure corresponding to the extraction-condensing condition of the unit, and determine the mutual relationship between the electric load and the heat load under the extraction-condensing condition. Then, according to the mutual relationship between the electric load and the heat load under the extraction-condensing condition, determine the operation domain limit line of the extraction-condensing condition, specifically: construct the variable operating condition function form [P e , D dyr = f(D0, Q h ), where: P e extraction-condensing unit electric load MW, Q hLet \(GJ / h\) be the thermal load of the extraction condensing unit, \(t / h\) be the main steam flow rate of the extraction condensing unit, and \(t / h\) be the steam inlet flow rate of the low-pressure cylinder of the extraction condensing unit. This function gives the relationship between \(D_0\) and \(D\). dyr and then the electrical load \(P\) of the extraction condensing unit can be obtained dyr as well as the thermal load \(Q\) of the extraction condensing unit e The definition threshold (i.e., the value range of the above parameters) and the corresponding rule (i.e., the mutual relationship between the above parameters) of this function can be determined according to the actual situation of the unit; according to the above function relationship, that is, the value range of the maximum extraction steam volume of the unit and the mutual relationship between the parameters, within the range from zero to the maximum extraction steam volume, several groups of extraction steam volumes are selected at equal intervals, and according to the mutual relationship between the electrical load and the thermal load under the extraction condensing condition ([P h ,D e = f(D0,Q dyr ) function relationship), the corresponding main steam volume, electrical load, and thermal load are calculated, and the first data group of main steam volume, electrical load, and thermal load is generated; according to the range between the minimum main steam volume and the maximum main steam volume of the unit, several groups of main steam volumes are selected at equal intervals, and several groups of main steam volume, electrical load, and thermal load are calculated according to the mutual relationship between the electrical load and the thermal load under the extraction condensing condition; according to the first data group and the second data group, the operating domain under the extraction condensing condition is determined. Specifically, according to the form of the variable condition function of the extraction condensing unit [P h ,D e = f(D0,Q dyr )), two types of cyclic value-taking methods in which the main steam volume and the thermal load change according to a certain step size (i.e., a certain value-taking interval) can be constructed to select several values of extraction steam volume and main steam volume for calculation. The process of the first type of cyclic value-taking is as follows: the thermal load takes values cyclically from zero to the maximum value range. The process of the second type of cyclic value-taking is as follows: the main steam volume takes values cyclically from the maximum main steam volume to the minimum main steam volume range, and a condition judgment of the minimum steam inlet volume of the low-pressure cylinder is embedded in the process of the second type of cyclic value-taking. If the minimum steam inlet volume of the low-pressure cylinder is not satisfied, the cyclic value-taking process ends.

[0056] It also includes: dividing the steam turbine into two parts consisting of the regulating stage to the extraction port and the extraction port to the condenser, and then using the Flügel formula to determine the corresponding extraction steam pressure under the condition of zero output of the low-pressure cylinder of the extraction condensing unit, and determining the mutual relationship between the electrical load and the thermal load under the condition of zero output of the low-pressure cylinder. Then, according to the mutual relationship between the electrical load and the thermal load under the condition of zero output of the low-pressure cylinder, the operating line of zero output of the low-pressure cylinder is determined. Specifically: constructing the form of the variable condition function of the extraction condensing unit [P h ,Q e = f(D0,D h ), where: P dyr is the electrical load of the extraction condensing unit in MW, Q e is the thermal load of the extraction condensing unit in MWh where \(GJ / h\) is the thermal load of the extraction-condensing unit, \(t / h\) is the main steam flow rate of the extraction-condensing unit, and \(D\) dyr is the steam flow rate into the low-pressure cylinder of the extraction-condensing unit. Under this operating condition, since the electric and thermal loads of the unit correspond one-to-one when the low-pressure cylinder has zero output, this function gives the relationship between \(D_0\) and \(D\) dyr , and then the electric load \(P\) of the extraction-condensing unit can be obtained e as well as the thermal load \(Q\) of the extraction-condensing unit h . The definition domain (i.e., the value range of the above parameters) and the corresponding rule (i.e., the mutual relationship between the above parameters) of this function can be determined according to the actual situation of the unit; according to the above function relationship, that is, the value range of the maximum main steam flow rate of the unit and the mutual relationship between the parameters, several groups of main steam flow rates are evenly selected from the interval between the minimum and maximum main steam flow rates of the unit, and several groups of third data sets of main steam flow rate, electric load, and thermal load are calculated according to the mutual relationship between the electric load and the thermal load under the condition of zero output of the low-pressure cylinder, and a zero-output operation line of the low-pressure cylinder is generated. Specifically, according to the above function \([P\) e , \(Q\) h \(]=f(D_0,D\) dyr ), the main steam flow rate is cyclically sampled at a certain step size (i.e., a certain sampling interval) from the maximum main steam flow rate to the minimum main steam flow rate, and the calculated electric and thermal loads are respectively recorded in the third data set, and then a zero-output operation condition line \(EF\) with the thermal load as the abscissa and the electric load as the ordinate is obtained.

[0057] According to the electric-thermal operation domain of the extraction-condensing unit under the extraction-condensing condition and the zero-output operation line diagram of the low-pressure cylinder of the extraction-condensing unit, and then using the method of mathematical fitting to determine the energy consumption of the extraction-condensing unit under the extraction-condensing condition and the energy consumption of the extraction-condensing unit under the zero-output condition of the low-pressure cylinder. In this step, it can be expressed by the function relationship as \(B\) tot \(=f(P\) e , \(Q\) h ), where \(B\) tot is the specific power consumption. Then the energy consumption of the extraction-condensing unit under the extraction-condensing condition can be expressed as: \([P\) e , \(D\) dyr , \(B\) tot \(]=f(D_0,Q\) h ); the energy consumption of the extraction-condensing unit under the zero-output condition of the low-pressure cylinder can be expressed as \([P\) e , \(Q\) h , \(B\) tot \(]=f(D_0,D\) dyr ). Also, since the electric load and the thermal load correspond one-to-one under the zero-output condition of the low-pressure cylinder, it can be simplified as \(B\) tot \(=f(Q\) h) According to the corresponding mathematical relationship, the energy consumption under the extraction-condensing operation mode is a region, and the energy consumption under the zero output of the low-pressure cylinder operation mode is a line, corresponding to the extraction-condensing electric-heat operation region of the extraction-condensing unit and the zero output operation line diagram of the low-pressure cylinder of the extraction-condensing unit.

[0058] Specifically, in the steps of determining the energy consumption of the extraction-condensing unit under the extraction-condensing operation mode and the energy consumption under the zero output of the low-pressure cylinder operation mode, the following formula is used to calculate the total operation benefit of the extraction-condensing unit under the extraction-condensing operation mode and the zero output of the low-pressure cylinder operation mode:

[0059] W ope =E e ×P e +E q ×Q h -B tot ×C0

[0060] In the formula: W ope is the operation benefit of the extraction-condensing unit, with the unit of CNY·h -1 , E e is the reference electricity price, with the unit of CNY·(MW·h) -1 , P e is the electric load of the extraction-condensing unit, with the unit of MW, E q is the reference heat price, with the unit of CNY·GJ -1 , Q h is the heat load of the extraction-condensing unit, with the unit of GJ·h -1 , C0 is the reference coal price, with the unit of CNY·t -1 , B tot is the total coal consumption of the extraction-condensing unit, with the unit of t·h -1 .

[0061] Furthermore, after obtaining the total operation benefit W ope1 of the extraction-condensing unit under the extraction-condensing operation mode and the total operation benefit W ope2 of the extraction-condensing unit under the zero output of the low-pressure cylinder operation mode, the following formula can be used to calculate the benefit difference ΔW (unit: / CNY·h -1 ):

[0062] ΔW=W ope1 -W ope2

[0063] Specifically, to calculate the peak shaving compensation income under the zero output of the low-pressure cylinder operation mode, including using the following formula to calculate the peak shaving compensation income of the unit:

[0064]

[0065] In the formula: W p-s is the peak shaving income of the unit, with the unit of CNY·h -1 , P e0is the unit capacity, in MW, R k is the upper limit of the peak shaving load rate of the k-th gear, R is the unit load rate, S k is the peak shaving compensation offer for the k-th gear, in CNY·(MW·h) -1 .

[0066] In the process of constructing the comparison chart of peak shaving compensation and benefit difference for the zero output of the low-pressure cylinder of the extraction-condensing unit according to the difference between the peak shaving compensation income and the benefit of the low-pressure cylinder zero output unit, the following can be established according to the relationship between the corresponding parameters (known from the unit operation status):

[0067] [P e ,B tot ,ΔW,W p-s =f(Q h ,E e ,E q ,C0,R k ,S k )

[0068] This functional relationship is obtained, and in the above-mentioned way of taking numbers in a loop, by changing some variables to determine the values of the remaining variables, and recording them in the fourth data set. Finally, a double y-axis graph as shown Figure 2 is established, with the heat load as the abscissa and the total operating income difference and the zero output peak shaving income as the ordinates, and this graph reflects the benefits of the zero output of the low-pressure cylinder condition.

[0069] Specifically, the judgment rule for whether the extraction-condensing unit changes from the extraction-condensing condition to the zero output of the low-pressure cylinder condition is as follows: when the sum of the benefit difference and the unit peak shaving compensation income is not greater than 0, the extraction-condensing heating mode of the extraction-condensing unit is maintained; when the sum of the benefit difference and the unit peak shaving compensation income is greater than 0, it is switched to the zero output of the low-pressure cylinder condition of the extraction-condensing unit.

[0070] In the process of constructing the extraction-condensing electric-heat operation domain and the zero output line graph of the low-pressure cylinder of the extraction-condensing unit and determining the energy consumption of the extraction-condensing condition and the zero output of the low-pressure cylinder condition of the extraction-condensing unit in the present invention, the method of least squares polynomial fitting is used for mathematical fitting. For example: using the least squares polynomial fitting (first order) to perform mathematical fitting on the limit lines of the extraction-condensing electric-heat operation domain and the zero output line of the low-pressure cylinder condition; using the least squares polynomial fitting to perform mathematical fitting on the unit energy consumption, where the energy consumption fitting of the extraction-condensing condition of the extraction-condensing unit uses a fourth-degree binomial fitting, and the energy consumption fitting of the zero output of the low-pressure cylinder condition of the extraction-condensing unit uses a first-order fitting.

[0071] The above embodiments are only the preferred embodiments of the present invention, and cannot be used to limit the scope of protection of the present invention. Any non-substantive changes and substitutions made by those skilled in the art on the basis of the present invention fall within the scope of protection required by the present invention.

Claims

1. An optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit, characterized in that, Including: S1: Conduct variable operating condition calculations for the extraction-condensing unit under the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition, and construct the extraction-condensing operating condition electro-thermal operation domain and the zero output of the low-pressure cylinder operating line graph of the extraction-condensing unit; S2: According to the extraction-condensing operating condition electro-thermal operation domain and the zero output of the low-pressure cylinder operating line graph of the extraction-condensing unit, and using the method of mathematical fitting to determine the energy consumption of the extraction-condensing unit under the extraction-condensing operating condition and the energy consumption of the zero output of the low-pressure cylinder operating condition; S3: According to the extraction-condensing operating condition electro-thermal operation domain and the zero output of the low-pressure cylinder operating line graph of the extraction-condensing unit, judge the "conjugate area" where the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition of the extraction-condensing unit can supply the same heat load; S4: According to the energy consumption of the extraction-condensing unit under the extraction-condensing operating condition and the energy consumption of the zero output of the low-pressure cylinder operating condition within the "conjugate area", compare the operating benefits of the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition, and calculate the benefit difference between the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition; S5: Account for the peak shaving compensation income of the zero output of the low-pressure cylinder operating condition; S6: According to the peak shaving compensation income of the zero output of the low-pressure cylinder operating condition and the benefit difference, construct a comparison graph of the peak shaving compensation and the benefit difference of the zero output of the low-pressure cylinder operating condition of the extraction-condensing unit; S7: Combine the comparison graph of the peak shaving compensation and the benefit difference of the zero output of the low-pressure cylinder operating condition of the extraction-condensing unit to determine whether the extraction-condensing unit changes to the zero output of the low-pressure cylinder operation, so as to construct a judgment rule on whether the extraction-condensing unit changes from the extraction-condensing operating condition to the zero output of the low-pressure cylinder operating condition; In the step of determining the energy consumption of the extraction-condensing unit under the extraction-condensing operating condition and the energy consumption of the zero output of the low-pressure cylinder operating condition, the following formula is used to calculate the total operating benefit of the extraction-condensing unit under the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition: W ope = E e × P e + E q × Q h - B tot × C0; Where: W ope is the operation benefit of the unit, with the unit of CNY·h -1 ; E e is the reference electricity price, with the unit of CNY·(MW·h) -1 ; P e is the electrical load of the unit, with the unit of MW; E q is the reference heat price, with the unit of CNY·GJ -1 ; Q h is the heat load of the unit, with the unit of GJ·h -1 ; C0 is the reference coal price, with the unit of CNY·t -1 ; B tot is the total coal consumption of the unit, with the unit of t·h -1 .

2. The optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit according to claim 1, characterized in that The specific steps of constructing the extraction-condensing operating condition electro-thermal operation domain and the zero output of the low-pressure cylinder operating line graph of the extraction-condensing unit include: Construct a coordinate system with the heat load of the extraction-condensing unit as the abscissa and the electric load of the extraction-condensing unit as the ordinate; According to the selected operating limit conditions of the extraction-condensing unit, determine the operating boundary of the extraction-condensing unit within the coordinate system; Select a number of known and discretely distributed reference operating conditions to calculate the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition of the extraction-condensing unit, and determine the extraction-condensing operating domain limit line and the zero output of the low-pressure cylinder operating line.

3. The optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit according to claim 2, characterized in that, Calculating the extraction-condensing operating condition and the zero output of the low-pressure cylinder operating condition of the extraction-condensing unit specifically includes: Use the Flügel formula to determine the extraction steam pressure corresponding to the extraction-condensing operating condition of the unit, and determine the mutual relationship between the electric load and the heat load under the extraction-condensing operating condition. Then, according to the mutual relationship between the electric load and the heat load under the extraction-condensing operating condition, determine the extraction-condensing operating domain limit line; Use the Flügel formula to determine the extraction steam pressure corresponding to the zero output of the low-pressure cylinder operating condition of the unit, and determine the mutual relationship between the electric load and the heat load under the zero output of the low-pressure cylinder operating condition. Then, according to the mutual relationship between the electric load and the heat load under the zero output of the low-pressure cylinder operating condition, determine the zero output of the low-pressure cylinder operating line.

4. A method for optimizing the operation of a condensing extraction unit with zero output of the low-pressure cylinder according to claim 3, characterized in that, According to the mutual relationship between the electric load and the heat load under the extraction-condensing operating condition to determine the extraction-condensing operating domain limit line, specifically including: According to the maximum extraction steam volume of the unit, within the range from zero to the maximum extraction steam volume, several groups of the extraction steam volume are selected at equal intervals, and the corresponding main steam volume, electric load, and heat load are calculated according to the mutual relationship between the electric load and the heat load under the extraction-condensing operation condition, and the first data set of the main steam volume, the electric load, and the heat load is generated; within the range between the minimum main steam volume and the maximum main steam volume of the unit, several groups of the main steam volume are selected at equal intervals, and several groups of the main steam volume, the electric load, and the heat load are calculated according to the mutual relationship between the electric load and the heat load under the extraction-condensing operation condition, and the second data set of the main steam volume, the electric load, and the heat load is generated; the operation domain of the extraction-condensing operation condition is determined according to the first data set and the second data set; Determine the zero output operation line of the low-pressure cylinder according to the mutual relationship between the electric load and the heat load under the zero output condition of the low-pressure cylinder, specifically including: Within the range between the minimum main steam volume and the maximum main steam volume of the unit, several groups of the main steam volume are selected at equal intervals, and several groups of the main steam volume, the electric load, and the heat load are calculated according to the mutual relationship between the electric load and the heat load under the zero output condition of the low-pressure cylinder, and the zero output operation line of the low-pressure cylinder is generated.

5. A method for optimizing the operation of a condensing extraction unit with zero output of the low-pressure cylinder according to claim 1, characterized in that, Use the following formula to calculate the benefit difference: ΔW = W ope1 -W ope2 where: ΔW is the difference in total operating income between the extraction-condensing operation mode and the zero output of the low-pressure cylinder, with the unit of CNY·h -1 ; W ope1 and W ope2 respectively represent the total operating efficiency of the extraction-condensing unit under the extraction-condensing operating condition and the total operating efficiency of the extraction-condensing unit under the condition of zero output of the low-pressure cylinder of the extraction-condensing unit.

6. The optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit according to claim 1, characterized in that Account for the peak shaving compensation benefit of the zero output condition of the low-pressure cylinder, including calculating the peak shaving compensation benefit of the unit by the following formula: Where: W p-s is the peak shaving revenue of the unit / CNY·h -1 , P e0 is the unit capacity / MW, R k is the upper limit of the peak shaving load rate of the k-th gear, R is the unit load rate, S k is the peak shaving compensation quotation of the k-th gear / CNY·(MW·h) -1 .

7. A method for optimizing the operation of a condensing extraction unit with zero output of the low-pressure cylinder according to claim 1, characterized in that, The judgment rule for whether the extraction-condensing unit changes from the extraction-condensing operation condition to the zero output condition of the low-pressure cylinder is specifically: When the sum of the benefit difference and the peak shaving compensation benefit of the unit is not greater than 0, maintain the heating mode of the extraction-condensing operation condition of the extraction-condensing unit; when the sum of the benefit difference and the peak shaving compensation benefit of the unit is greater than 0, switch to the zero output condition of the low-pressure cylinder of the extraction-condensing unit for operation.

8. The optimized operation method for zero output of the low-pressure cylinder of a condensing extraction unit according to claim 1, characterized in that During the process of constructing the electric-heat operation domain of the extraction-condensing operation condition and the zero output operation line diagram of the low-pressure cylinder of the extraction-condensing unit and determining the energy consumption of the extraction-condensing operation condition and the energy consumption of the zero output condition of the low-pressure cylinder of the extraction-condensing unit, the least squares polynomial fitting method is used for mathematical fitting.

9. The optimized operation method for zero output of the low-pressure cylinder of a back-pressure condensing unit according to claim 2, characterized in that, According to the selected operation limit conditions of the extraction-condensing unit, determine the operation boundary of the extraction-condensing unit in the coordinate system, specifically including: Determine the first limit boundary according to the limit condition that the main steam volume is less than the maximum continuous evaporation capacity of the boiler; Determine the second limit boundary according to the limit condition that the inlet steam volume of the low-pressure cylinder is greater than the minimum condensing flow rate; Determine the third limit boundary according to the limit condition that the unit load is greater than the load under the stable combustion condition of the boiler.

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