Method for fitting variable load coal consumption characteristic curve of coal-fired power generating unit

Abstract

The invention relates to a variable load coal consumption characteristic curve fitting method for a coal-fired power generation unit, which can be applied to predictive analysis of coal consumption rates during peak-load and variable-load operation of various coal-fired power generation units. According to the method, the problems that a large amount of thermodynamic cycle information of the unit is needed and the solving process is complex when the variable load coal consumption result of the coal-fired power unit is solved in a traditional simulation or programming mode are solved. The basic form of a curve fitting formula is superposition of a simple power function and a sine function, and a complex iteration process in traditional calculation can be avoided by using a display formula for calculation. Only two unknown coefficients are included in the fitting formula, and according to research on the coal consumption characteristics of a large number of coal-fired power generation units, a fitting formula coefficient value table suitable for different reheating stages, initial parameters, unit operation modes, cooling modes and valve control modes is summarized. According to the known characteristics of the coal-fired power generation unit, the variable load coal consumption characteristics of the coal-fired power generation unit can be predicted by applying the fitting formula and the coefficient table.

Description

Technical Field

[0001] The invention belongs to the technical field of coal consumption characteristics of coal-fired power generation units deviating from a reference operating condition, and in particular relates to a method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit. Background Art

[0002] The strategic goal of "double carbon" promotes the construction of a new power system with renewable energy as the main body. Due to the strong time-varying characteristics of renewable energy generation, in order to ensure the stability of the power grid load, coal-fired generating units need to be configured as peak-shaving units to absorb the smooth access to the grid of new energy generation. The use of coal-fired generating units for peak-shaving will cause the units to deviate from the baseline operating conditions for a long time, and the coal consumption rate will change accordingly. Studying the coal consumption characteristics of the unit under variable load scenarios provides a reference for the low-coal consumption dispatch optimization of units in new power systems, which is of great significance to ensuring the stability and economy of the power system. The traditional research methods for variable load of coal-fired generating units are mainly based on software methods of GSE modeling and simulation or programming and calculation methods based on Matlab and C++. The above methods require complete unit topology and unit thermal cycle information, etc. When applied to the dispatch optimization of multiple units in the new power system, modeling research needs to be carried out for each unit, which is relatively complicated and not suitable for predictive research with less known unit information. There are problems such as complex process, low operability for new power systems containing multiple units, and not suitable for predictive research with partially known unit information. Summary of the invention

[0003] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit. The present invention can well calculate the coal consumption characteristics of any load of various existing coal-fired power generation units, and predict and simulate the coal consumption characteristics of the coal-fired power generation units under all operating conditions. It has the advantages of simple fitting form, high accuracy, less reliance on basic thermal information of the unit, and strong operability. It can provide a powerful tool for the study of problems such as optimal scheduling of new power systems and operating characteristics of coal-fired power generation units deviating from baseline operating conditions.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit comprises the following steps:

[0006] Step 1: Obtain the basic information characteristics of the coal-fired power generation unit required for fitting the coal consumption characteristic curve of the coal-fired power generation unit under variable operating conditions, including the reheating stage and cooling method of the coal-fired power generation unit; the basic characteristics of the coal-fired power generation unit under variable operating conditions, including the variable operating mode of the unit and the control form of the main steam valve; the lower heating value LHV of the fuel;

[0007] Step 2: Obtain the benchmark operating condition information of the coal-fired power generation unit required for fitting the variable operating condition coal consumption characteristic curve of the coal-fired power generation unit, including the benchmark operating condition main steam enthalpy h0, the benchmark operating condition steam turbine heat rate q FL , boiler efficiency η b and pipeline efficiency η p ;

[0008] Step 3: Based on the benchmark steam turbine heat rate q FL , boiler efficiency η b , pipeline efficiency η p And the basic information characteristics of the fuel, use the coal consumption rate calculation formula: The base condition coal consumption rate b is calculated FL ;

[0009] Step 4: Based on the coefficient table that has been prepared, see Table 1, combined with the basic characteristics of the coal-fired power generation unit under variable operating conditions obtained in Step 1, the reheat coefficient Z required for the fitting curve is obtained by looking up the table. R , cooling coefficient L R and valve throttling correction factor f;

[0010] Table 1

[0011]

[0012]

[0013] Step 5: Based on the reheat coefficient Z R , cooling coefficient L R and the base case main steam enthalpy h0, using R = Z R ·h0+L R The linear calculation formula is used to solve the degradation coefficient R required for the fitting curve;

[0014] Step 6: Based on the benchmark coal consumption rate b obtained in step 3 FL , the valve throttling correction factor f obtained in step 4, the degradation coefficient R obtained in step 5, and the power-sine function superposition formula: b = b FL ·{X -R + sin[f·(1-X)]}, solve the coal consumption rate b of the coal-fired generating unit under any coal-fired generating unit load rate X scenario, the unit is g / kWh; where X is the load rate of the coal-fired generating unit, that is, the ratio of the electric load under the new operating condition to the electric load under the benchmark operating condition; starting from 100% load rate, select the preset load rate intervals to solve the coal consumption rate in turn, connect the obtained data points, and obtain the variable load coal consumption characteristic curve of the coal-fired generating unit.

[0015] The reheating stages of the coal-fired power generation unit described in step 1 are divided into no reheating, single reheating and double reheating; the cooling methods of the coal-fired power generation unit are divided into water cooling and air cooling; the variable operating mode of the coal-fired power generation unit is divided into constant pressure operation and sliding pressure operation; the main steam valve control form is divided into single valve control and sequential valve control.

[0016] The fuel lower heating value LHV described in step 1 is obtained from the fuel information form for the power plant units.

[0017] In step 2, the benchmark operating conditions are divided into the following according to the operating requirements: heat rate acceptance condition THA, nameplate condition TRL, valve fully open condition VWO and maximum continuous operation condition T-MCR.

[0018] The main steam enthalpy h0 of the base condition in step 2 can be directly read from the heat balance diagram of the base condition of the coal-fired power generation unit, or can be obtained by looking up the main steam temperature T0 and the main steam pressure P0 using the water vapor thermodynamic property table; the heat rate of the steam turbine under the base condition q FL Can be directly read from the thermal balance diagram of the benchmark operating condition of the coal-fired generator set; boiler efficiency η b and pipeline efficiency η p Obtained from the book on thermal characteristics of boilers of coal-fired power generation units.

[0019] The coefficient table in step 4 is developed based on the study of 25 coal-fired generating units covering the basic characteristics of 538℃, 566℃ and 600℃ temperature levels, no reheat, single reheat and double reheat, water cooling and air cooling, constant pressure operation and sliding pressure operation, single valve control and sequential valve control.

[0020] In step 6, the variable load coal consumption characteristic curve of the coal-fired power generation unit is obtained starting from 100% load rate, and the load rate interval is selected according to the fitting accuracy requirement. A series of data points are solved using the power function-sine function superposition formula, and the fitting curve is obtained by connecting them.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The method of the present invention does not require a detailed understanding of the topological structure and thermal cycle process of the coal-fired power generation unit. It only needs to obtain basic information such as the energy consumption of the baseline operating condition, the number of reheating stages, the cooling method, the operation mode of the coal-fired power generation unit, the main steam valve control method, and the main steam temperature and main steam pressure. The coefficient table and the power function-sine function superposition formula provided by the present invention can be used to calculate the coal consumption rate results of the coal-fired power generation unit under various load conditions, and make a coal consumption characteristic curve of the coal-fired power generation unit under variable load operation. The method of the present invention is applicable to various types of coal-fired power generation units, has a simple fitting form, high accuracy, relies on less basic information of the coal-fired power generation unit, has strong operability, and avoids traditional iterative algorithms in the form of explicit formulas. It can provide a powerful tool for research on problems such as optimization scheduling of new power systems and operation characteristics of coal-fired power generation units that deviate from the baseline operating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, the present invention provides a method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit, comprising the following steps:

[0025] Step 1: Obtain the basic information characteristics of the coal-fired power generation unit required for fitting the coal consumption characteristic curve of the coal-fired power generation unit under variable operating conditions, including the reheating stage and cooling method of the coal-fired power generation unit; the basic characteristics of the coal-fired power generation unit under variable operating conditions, including the variable operating mode of the unit and the control form of the main steam valve; the lower heating value LHV of the fuel;

[0026] Step 2: Obtain the benchmark operating condition information of the coal-fired power generation unit required for fitting the variable operating condition coal consumption characteristic curve of the coal-fired power generation unit, including the benchmark operating condition main steam enthalpy h0, the benchmark operating condition steam turbine heat rate q FL , boiler efficiency η b and pipeline efficiency η p ;

[0027] Step 3: Based on the benchmark steam turbine heat rate q FL , boiler efficiency η b , pipeline efficiency η p And the basic information characteristics of the fuel, use the coal consumption rate calculation formula: The base condition coal consumption rate b is calculated FL ;

[0028] Step 4: Based on the coefficient table that has been prepared, see Table 1, combined with the basic characteristics of the coal-fired power generation unit under variable operating conditions obtained in Step 1, the reheat coefficient Z required for the fitting curve is obtained by looking up the table. R , cooling coefficient L R and valve throttling correction factor f;

[0029] Table 1

[0030]

[0031] Step 5: Based on the reheat coefficient Z R , cooling coefficient L R and the base case main steam enthalpy h0, using R = Z R ·h0+L R The linear calculation formula is used to solve the degradation coefficient R required for the fitting curve;

[0032] Step 6: Based on the benchmark coal consumption rate b obtained in step 3 FL , the valve throttling correction factor f obtained in step 4, the degradation coefficient R obtained in step 5, and the power-sine function superposition formula: b = b FL ·{X -R + sin[f·(1-X)]}, solve the coal consumption rate b of the coal-fired generating unit under any coal-fired generating unit load rate X scenario, the unit is g / kWh; where X is the load rate of the coal-fired generating unit, that is, the ratio of the electric load under the new operating condition to the electric load under the benchmark operating condition; starting from 100% load rate, select the preset load rate intervals to solve the coal consumption rate in turn, connect the obtained data points, and obtain the variable load coal consumption characteristic curve of the coal-fired generating unit.

[0033] Preferably, the reheating stages of the coal-fired power generation unit described in step 1 are divided into no reheating, single reheating and double reheating; the cooling methods of the coal-fired power generation unit are divided into water cooling and air cooling; the variable operating mode of the coal-fired power generation unit is divided into constant pressure operation and sliding pressure operation; the main steam valve control form is divided into single valve control and sequence valve control. The detailed classification of coal-fired power generation units covers the operating characteristics of the coal-fired power generation units under different operating conditions, and improves the comprehensiveness and accuracy of variable operating condition modeling.

[0034] Preferably, the fuel lower heating value LHV in step 1 is obtained from the fuel information form for the power plant units. Directly obtaining the power plant coal data reflects the actual quality and quantity of coal used by the power plant, which improves the scientificity and accuracy of coal quality modeling.

[0035] Preferably, the benchmark operating conditions in step 2 are divided into: heat rate acceptance condition THA, nameplate condition TRL, valve full open condition VWO and maximum continuous operation condition T-MCR according to operation requirements. The benchmark operating conditions divided by operation requirements cover different valve opening and closing and water replenishment conditions of coal-fired power generation units, which improves the accuracy of benchmark operating condition modeling and solution.

[0036] Preferably, the base operating condition main steam enthalpy h0 in step 2 can be directly read from the base operating condition heat balance diagram of the coal-fired power generation unit, or can be obtained by looking up the main steam temperature T0 and the main steam pressure P0 using the water vapor thermodynamic property table; the base operating condition steam turbine heat rate qFL Can be directly read from the thermal balance diagram of the benchmark operating condition of the coal-fired generator set; boiler efficiency η b and pipeline efficiency η p Obtain data from the thermal characteristics book of the boiler of the coal-fired power generation unit. Obtaining data from the heat balance diagram and the thermal characteristics book reduces the computing power and time cost of iterative solution using simulation programming algorithms.

[0037] Preferably, the coefficient table in step 4 is prepared based on the study of 25 coal-fired power generation units covering 538°C, 566°C and 600°C temperature levels, no reheat, single reheat and double reheat, water cooling and air cooling, constant pressure operation and sliding pressure operation, single valve control and sequence valve control basic characteristics. The coefficient table (see Table 1) gives the reheat coefficient Z of condensing units with different characteristics R , cooling coefficient L R , the method for determining the valve throttling correction coefficient f is convenient for practical engineering applications.

[0038] Preferably, the variable load coal consumption characteristic curve of the coal-fired power generation unit obtained in step 6 starts from 100% load rate, selects the load rate interval according to the fitting accuracy requirement, uses the power function-sine function superposition formula to solve a series of data points, and connects them to obtain the fitting curve. The relative error between the coal consumption characteristic curve fitted by the variable load coal consumption characteristic curve fitting method of the coal-fired power generation unit provided by this embodiment and the actual curve sample point is less than 1.5%, which meets the engineering accuracy requirements and can reflect the real coal consumption characteristics of the unit.

[0039] The present invention solves the problem that the traditional simulation or programming method requires a lot of unit thermal cycle information and the solution process is complicated when solving the variable load coal consumption results of coal-fired power generation units. The basic form of the curve fitting formula of the present invention is the superposition of a simple power function and a sine function. The use of a display formula calculation can avoid the complex iterative process in traditional calculations. There are only two unknown coefficients contained in the fitting formula, and based on the study of the coal consumption characteristics of a large number of coal-fired power generation units, the present invention summarizes the fitting formula coefficient value table suitable for different reheating stages, initial parameters, unit operation modes, cooling methods, and valve control methods. Through the known characteristics of the coal-fired power generation unit, the fitting formula and coefficient table of the present invention can be used to predict the variable load coal consumption characteristics of the coal-fired power generation unit.

Claims

1. A method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit, characterized in that: The steps include: Step 1: Obtain the basic information characteristics of the coal-fired power generation unit required for fitting the coal consumption characteristic curve of the coal-fired power generation unit under variable operating conditions, including the reheating stage and cooling method of the coal-fired power generation unit; the basic characteristics of the coal-fired power generation unit under variable operating conditions, including the variable operating mode of the unit and the control form of the main steam valve; the lower heating value LHV of the fuel; Step 2: Obtain the benchmark operating condition information of the coal-fired power generation unit required for fitting the variable operating condition coal consumption characteristic curve of the coal-fired power generation unit, including the benchmark operating condition main steam enthalpy h0, the benchmark operating condition steam turbine heat rate q FL , boiler efficiency η b and pipeline efficiency η p ; Step 3: Based on the benchmark steam turbine heat rate q FL , boiler efficiency η b , pipeline efficiency η p And the basic information characteristics of the fuel, use the coal consumption rate calculation formula: The base condition coal consumption rate b is calculated FL ; Step 4: Based on the coefficient table that has been prepared, see Table 1, combined with the basic characteristics of the coal-fired power generation unit under variable operating conditions obtained in Step 1, the reheat coefficient Z required for the fitting curve is obtained by looking up the table. R , cooling coefficient L R and valve throttling correction factor f; Table 1 Step 5: Based on the reheat coefficient Z R , cooling coefficient L R and the base case main steam enthalpy h0, using R = Z R ·h0+L R The linear calculation formula is used to solve the degradation coefficient R required for the fitting curve; Step 6: Based on the benchmark coal consumption rate b obtained in step 3 FL , the valve throttling correction factor f obtained in step 4, the degradation coefficient R obtained in step 5, and the power-sine function superposition formula: b = b FL ·{X -R + sin[f·(1-X)]}, solve the coal consumption rate b of the coal-fired generating unit under any coal-fired generating unit load rate X scenario, the unit is g / kWh; where X is the load rate of the coal-fired generating unit, that is, the ratio of the electric load under the new operating condition to the electric load under the benchmark operating condition; starting from 100% load rate, select the preset load rate intervals to solve the coal consumption rate in turn, connect the obtained data points, and obtain the variable load coal consumption characteristic curve of the coal-fired generating unit.

2. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: The reheating stages of the coal-fired power generation unit described in step 1 are divided into no reheating, single reheating and double reheating; the cooling methods of the coal-fired power generation unit are divided into water cooling and air cooling; the variable operating mode of the coal-fired power generation unit is divided into constant pressure operation and sliding pressure operation; the main steam valve control form is divided into single valve control and sequential valve control.

3. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: The fuel lower heating value LHV described in step 1 is obtained from the fuel information form for the power plant units.

4. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: In step 2, the benchmark operating conditions are divided into the following according to the operating requirements: heat rate acceptance condition THA, nameplate condition TRL, valve fully open condition VWO and maximum continuous operation condition T-MCR.

5. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: The main steam enthalpy h0 of the base condition in step 2 can be directly read from the heat balance diagram of the base condition of the coal-fired power generation unit, or can be obtained by looking up the main steam temperature T0 and the main steam pressure P0 using the water vapor thermodynamic property table; the heat rate of the steam turbine under the base condition q FL Can be directly read from the thermal balance diagram of the benchmark operating condition of the coal-fired generator set; boiler efficiency η b and pipeline efficiency η p It can be found in the thermal characteristics book of the boiler of the coal-fired power generation unit.

6. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: The coefficient table in step 4 is developed based on the study of 25 coal-fired generating units covering the basic characteristics of 538℃, 566℃ and 600℃ temperature levels, no reheat, single reheat and double reheat, water cooling and air cooling, constant pressure operation and sliding pressure operation, single valve control and sequential valve control.

7. The method for fitting a variable load coal consumption characteristic curve of a coal-fired power generation unit according to claim 1, characterized in that: In step 6, the variable load coal consumption characteristic curve of the coal-fired power generation unit is obtained starting from 100% load rate, and the load rate interval is selected according to the fitting accuracy requirement. A series of data points are solved using the power function-sine function superposition formula, and the fitting curve is obtained by connecting them.

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