A Calculation Method for Sliding Pressure Curve with Weighted Time-Series Energy Balance under All Operating Conditions

Abstract

The present invention provides a sliding pressure curve calculation method for weighted time-sequence energy balance under all operating conditions, including: S1: determining basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measuring the parameter values of each component of a thermal power unit; S2: performing time-sequence correction on the parameter values of each component of the thermal power unit; S3: sequentially inputting the parameter values of the thermal power unit after time-sequence correction into a sliding pressure curve calculation model for weighted time-sequence energy balance under all operating conditions to obtain a heat rate - main steam pressure curve of the thermal power unit; S4: determining a load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain a final sliding pressure curve. The present invention can solve the problem in the prior art that the variable load condition is not considered, resulting in low accuracy of the sliding pressure optimization curve, and further increasing the operating cost of the thermal power unit.

Description

Technical Field

[0001] The present invention belongs to the field of thermal power generation, and particularly relates to a calculation method for a sliding pressure curve with weighted time-sequence energy balance under all operating conditions. Background Art

[0002] At present, clean energy represented by wind power and photovoltaic power has developed rapidly, the adjustment of the power structure has been further deepened, renewable energy will gradually occupy the dominant position in the power system, and the utilization hours of thermal power generation have decreased year by year. Due to the natural characteristics of new energy sources such as wind and light, the power grid lacks more peak shaving capabilities. In this case, thermal power generating units have begun to transform from power supply type to power regulation type and undertake peak shaving operation tasks. While the thermal power generating units have large load changes, the main steam pressure is unstable, and the efficiency of the thermal power generating units has been greatly reduced. On the premise of meeting the peak shaving requirements, improving the operating economy of the units has become an urgent problem.

[0003] At present, the sliding pressure curves of most existing units come from the initial design curves provided by the steam turbine manufacturers, only considering the relationship between the electric load and the set value of the main steam pressure. However, a thermal power generating unit is a complex system with multi-parameter coupling and time-varying thermal cycle efficiency, which is a contradiction and unity. The existing conventional sliding pressure curve test optimization method tests the heat consumption rate under the main steam pressure at several typical load points, selects the lowest heat consumption rate as the optimal pressure under the typical load, and finally obtains the optimal sliding pressure curve through off-line calculation. Moreover, the optimal sliding pressure curve obtained by the above off-line calculation will gradually deviate from the actual optimal sliding pressure curve over time, resulting in the thermal power generating unit may deviate from the actual optimal sliding pressure curve for a long time between two sliding pressure optimization cycles, and further resulting in a higher heat consumption rate during the operation of the thermal power generating unit.

[0004] In order to improve the accuracy of the sliding pressure optimization of thermal power generating units, methods such as linear substitution, logistic regression, and intelligent iteration are also proposed now. By collecting unit data for calculation, the sliding pressure optimization curve is obtained. However, these optimization methods are also optimized under the condition of stable unit state, without considering the variable load condition, resulting in the unit not being able to operate at the cost optimal point in real time. Summary of the Invention

[0005] In view of this, the present invention provides a calculation method for a sliding pressure curve with weighted time-sequence energy balance under all operating conditions to solve the problem in the prior art that the variable load condition is not considered, resulting in low accuracy of the sliding pressure optimization curve and further increasing the operating cost of the thermal power generating unit.

[0006] An embodiment of the present invention provides a calculation method for a sliding pressure curve with weighted time-sequence energy balance under all operating conditions. The method includes:

[0007] S1: Determine the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measure the parameter values of the thermal power unit;

[0008] S2: Perform chronological correction on the parameter values of the thermal power unit;

[0009] S3: Input the parameter values of the thermal power unit after chronological correction into the sliding pressure curve calculation model of weighted chronological energy balance under all operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit;

[0010] S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve.

[0011] Optionally, the determination of the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation includes:

[0012] The method for heat rate calculation is:

[0013]

[0014] where, HR is the heat rate, with the unit of KJ / KWh; D r , zjs , cr , zjs , r , cr ,

[0016] ,

[0015] , fw , m , gjs , fw , m , cl , , gjs , is the main steam flow rate, with the unit of t / h; D r is the reheater steam flow rate, with the unit of t / h; D fw is the feed water flow rate, with the unit of t / h; D cr is the cold reheater flow rate, with the unit of t / h; D gjs is the superheater desuperheating water flow rate, with the unit of t / h; D zjs is the reheater desuperheating water flow rate, with the unit of t / h; H m is the main steam enthalpy, with the unit of Kj / kg; H r is the reheater steam enthalpy, with the unit of Kj / kg; H fw is the feed water enthalpy, with the unit of Kj / kg; H cr is the cold reheater steam enthalpy, with the unit of Kj / kg; H gjs is the superheater desuperheating water enthalpy, with the unit of Kj / kg; H zjs is the reheater desuperheating water enthalpy, with the unit of Kj / kg; N cl is the power generation of the thermal power unit, with the unit of KW;

[0015] Since each parameter is related to the temperature and pressure of the working fluid, the basic physical quantities and thermodynamic cycle parameters determined are:

[0016] Main steam flow rate, main steam temperature and main steam pressure; reheater steam flow rate, reheater steam temperature and reheater steam pressure; feed water flow rate, feed water temperature and feed water pressure; cold reheater flow rate, cold reheater temperature and cold reheater pressure; attemperator water flow rate for superheater, attemperator water temperature for superheater and attemperator water pressure for superheater; attemperator water flow rate for reheater, attemperator water temperature for reheater and attemperator water pressure for reheater.

[0017] Optionally, the sequential correction of each parameter value of the thermal power unit includes:

[0018] Measuring the time T required for the parameter transmission of each parameter measuring instrument of the thermal power unit to the DCS channel through an oscilloscope yb , checking the inertia time parameter T set in the DCS preprocessing g , measuring the time difference T of parameter transmission between different DPU of the DCS through an SOE measuring instrument w , obtaining the cycle time T of configuration calculation by checking the operation cycle and function block sequence of the DCS configuration page p , obtaining the delay time T of the jth parameter required for the parameter of the measuring instrument from the measuring instrument to the heat rate calculation function page j It is:

[0019] T j = T yb + T g + T w + T p

[0020] After obtaining the delay time of all parameters, taking the maximum delay time T of all parameter transmission times jmax , taking the difference between T jmax and T j to obtain the compensation time T of each parameter j1 :

[0021] T j1 = T jmax - T j

[0022] Among them, T j1 is the compensation time of the jth parameter, T jmax is the maximum delay time of all parameter transmission times, and T j is the delay time of the jth parameter;

[0023] By performing sequential correction of pure delay on the jth parameter, ensuring that all parameters are in the same time sequence, the correction formula is as follows:

[0024] Signal(X j1 ) = Signal(X j ) + delay(T j1)

[0025] Among them, Signal(X j1 ) is the parameter signal after the j-th timing correction, Signal(X j ) is the parameter signal before the j-th timing correction, and delay(T j1 ) is the delay signal of the j-th parameter.

[0026] Optionally, the calculation steps of the sliding pressure curve calculation model for the weighted timing energy balance under all operating conditions include:

[0027] Based on the parameter values of the thermal power unit after timing correction, judge the operating state of the thermal power unit, whether it is a steady-state condition or a dynamic condition;

[0028] When the thermal power unit is in a stable condition, substitute the parameter values of the thermal power unit after timing correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit;

[0029] When the thermal power unit is in a dynamic condition, use the feed water flow of the thermal power unit to perform dynamic timing correction on the main steam flow of the thermal power unit, substitute the main steam flow of the thermal power unit after dynamic timing correction and the parameter values of the thermal power unit into the heat rate calculation formula to obtain the equivalent heat rate under dynamic conditions; perform dynamic weighted timing correction on the main steam pressure of the thermal power unit to obtain the equivalent main steam pressure of the thermal power unit; combine the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve;

[0030] Perform weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments.

[0031] Optionally, the judgment of the operating state of the thermal power unit, whether it is a steady-state condition or a dynamic condition, based on the parameter values of the thermal power unit after timing correction includes:

[0032] Calculate the maximum change rate of each parameter of the thermal power unit according to the parameter values of the thermal power unit after timing correction. The calculation method of the maximum change rate of each parameter of the thermal power unit is:

[0033]

[0034] Among them, K(t) imax is the maximum change rate of the i-th parameter of the thermal power unit; K id is the change rate correction coefficient of the i-th parameter to ensure that the change rates of each parameter of the thermal power unit are in the same dimension; x(t) i is the actual value of the i-th parameter at time t;

[0035] Compare the maximum change rate of each parameter of the thermal power unit with the steady-state operating condition judgment value. If K(t) imax ≤K1, and the actual load instruction before CCS speed limit does not change, the thermal power unit is in steady-state operation; if there is K(t) imax >K1, and the actual load instruction before CCS speed limit shows a step change, the thermal power unit is in a dynamic operating condition.

[0036] Optionally, the dynamically timing correcting the main steam flow of the thermal power unit by using the feed water flow of the thermal power unit includes:

[0037] The thermal power unit quickly responds to the AGC load instruction by opening the high-pressure regulating valve to increase the main steam flow. After the main steam flow increases, the main feed water flow increases again, resulting in a deviation in the main steam flow and the main feed water flow. Therefore, the main steam flow of the thermal power unit is dynamically corrected as follows:

[0038] Signal(D fw1 )=Signal(D fw )+delay(T d )

[0039] Among them, Signal(D fw1 ) is the main steam flow signal of the thermal power unit after the dynamic time sequence correction, Signal(D fw ) is the main steam flow signal of the thermal power unit, delay(T d ) is the lag signal of the main steam flow of the thermal power unit relative to the feed water flow of the thermal power unit.

[0040] Optionally, performing weighted time sequence correction on the main steam pressure of the thermal power unit includes:

[0041] Through the fuel-main steam pressure response test, the change in main steam pressure ΔP when the fuel changes by 3 tons is obtained. T ;

[0042] In the early stage of load increase, the pressure deviation is small due to the heat storage of the boiler. In the middle stage of load increase, the heat storage of the boiler decreases and the dynamically increased coal amount has not yet generated energy, so the pressure deviation is the largest. In the late stage of load increase, the dynamically increased coal amount has generated energy and the pressure deviation decreases. Therefore, during the load increase period, the main steam pressure after weighted time series correction is:

[0043]

[0044]

[0045] During the load reduction period, the main steam pressure after weighted time sequence correction is:

[0046]

[0047]

[0048] Among them, P T is the main steam pressure after weighted time series correction, with the unit of MPa; P ST is the real-time value of the main steam pressure, with the unit of MPa; θ is the correction weight value at different times during the load increase stage; n is the dynamically increased coal quantity, with the unit of ton; the time range of t is affected by the operating state of the thermal power unit.

[0049] Optionally, substituting the parameter values of the thermal power unit after time series correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit includes:

[0050] Processing the parameter values of the thermal power unit after time series correction by using the least square method and the heat rate calculation formula to obtain the steady-state heat rate - main steam pressure curve f1(HR - P T ).

[0051] Combining the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve includes:

[0052] Using the least square method to determine the dynamic main steam pressure curve f2(HR - P T ) for the equivalent heat rate and the equivalent main steam pressure.

[0053] Optionally, performing a weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments includes:

[0054] Under steady-state conditions, since the parameters of the thermal power unit are stable, the obtained steady-state heat rate - main steam pressure curve is relatively accurate and has a heavier weight; under dynamic conditions, due to load increase and decrease, since the parameters of the thermal power unit are constantly changing, its weight is lighter, and the faster the dynamic load changes, the higher the uncertainty of the heat rate - main steam pressure curve under dynamic conditions and the lighter the weight;

[0055] f(HR - P T ) = αf1(HR - P T ) + βf2(HR - P T )

[0056] Among them, f(HR - P T ) is the heat rate - main steam pressure curve, α is the weight of the heat rate - main steam pressure curve under steady-state conditions; β is the weight of the heat rate - main steam pressure curve under dynamic conditions.

[0057] Optionally, determining the final sliding pressure curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule includes:

[0058] By analyzing the heat rate - main steam pressure curve of different load sections, according to the lowest heat rate rule, determining the optimal load - main steam curve to obtain the final sliding pressure curve.

[0059] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0060] The embodiments of the present invention provide a sliding pressure curve calculation method for weighted time - series energy balance under all operating conditions, including: S1: determining basic physical quantities and thermal cycle parameters according to the actual requirements of heat rate calculation, and measuring each parameter value of the thermal power unit; S2: performing time - series correction on each parameter value of the thermal power unit; S3: sequentially inputting each parameter value of the thermal power unit after time - series correction into the sliding pressure curve calculation model for weighted time - series energy balance under all operating conditions to obtain the heat rate - main steam pressure curve of the thermal power unit; S4: determining the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve. The present invention can solve the problem in the prior art that the variable load condition is not considered, resulting in low accuracy of the sliding pressure optimization curve and further increasing the operating cost of the thermal power unit. Description of the Drawings

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only 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.

[0062] Figure 1 is a schematic flow chart of a sliding pressure curve calculation method for weighted time - series energy balance under all operating conditions provided by an embodiment of the present invention;

[0063] Figure 2 is a schematic flow chart of the calculation of a sliding pressure curve calculation model for weighted time - series energy balance under all operating conditions provided by an embodiment of the present invention;

[0064] Figure 3 is a schematic diagram of the step - response curves of the main steam flow rate and the main feed - water flow rate provided by an embodiment of the present invention. Detailed Embodiments

[0065] In the following description, specific details such as specific system architectures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present invention. However, those skilled in the art should clearly understand that the present invention can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present invention.

[0066] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will be described through specific embodiments in conjunction with the accompanying drawings.

[0067] Embodiment 1

[0068] Please refer to the attached Figure 1 , Figure 1 A sliding pressure curve calculation method for weighted time-sequence energy balance under all operating conditions provided for the embodiment of the present invention includes:

[0069] S1: Determine the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measure the parameter values of each part of the thermal power unit;

[0070] S2: Perform time-sequence correction on the parameter values of each part of the thermal power unit;

[0071] S3: Input the parameter values of each part of the thermal power unit after time-sequence correction into the sliding pressure curve calculation model for weighted time-sequence energy balance under all operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit;

[0072] S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve.

[0073] In this embodiment, the calculation steps of the sliding pressure curve calculation model for weighted time-sequence energy balance under all operating conditions include:

[0074] Based on the parameter values of each part of the thermal power unit after time-sequence correction, judge the operating state of the thermal power unit, whether it is a steady-state condition or a dynamic condition;

[0075] If the thermal power unit is in a stable condition, substitute the parameter values of each part of the thermal power unit after time-sequence correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit;

[0076] When the thermal power unit is in a dynamic operating condition, the feed water flow rate of the thermal power unit is used to perform dynamic time series correction on the main steam flow rate of the thermal power unit. The main steam flow rate of the thermal power unit after dynamic time series correction and each parameter value of the thermal power unit are substituted into the heat rate calculation formula to obtain the equivalent heat rate under the dynamic operating condition; perform dynamic weighted time series correction on the main steam pressure of the thermal power unit to obtain the equivalent main steam pressure of the thermal power unit; determine the dynamic heat rate - main steam pressure curve in combination with the equivalent heat rate and the equivalent main steam pressure;

[0077] Perform weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments.

[0078] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows:

[0079] The embodiments of the present invention provide a method for calculating a sliding pressure curve with weighted time series energy balance under all operating conditions, including: S1: Determine the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measure each parameter value of the thermal power unit; S2: Perform time series correction on each parameter value of the thermal power unit; S3: Input each parameter value of the thermal power unit after time series correction into the sliding pressure curve calculation model with weighted time series energy balance under all operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit; S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve. The present invention can solve the problem in the prior art that the variable load operating condition is not considered, resulting in low accuracy of the sliding pressure optimization curve, and further increasing the operating cost of the thermal power unit.

[0080] Embodiment 2

[0081] Please refer to the appendix Figure 1 , Figure 1 which is a method for calculating a sliding pressure curve with weighted time series energy balance under all operating conditions provided by the embodiments of the present invention, including:

[0082] S1: Determine the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measure each parameter value of the thermal power unit;

[0083] S2: Perform time series correction on each parameter value of the thermal power unit;

[0084] S3: Input each parameter value of the thermal power unit after time series correction into the sliding pressure curve calculation model with weighted time series energy balance under all operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit;

[0085] S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve.

[0086] In this embodiment, determining the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation includes:

[0087] The method for calculating the heat rate is:

[0088]

[0089] where HR is the heat rate, with the unit of KJ / KWh; D m is the main steam flow rate, with the unit of t / h; D r is the reheater steam flow rate, with the unit of t / h; D fw is the feed water flow rate, with the unit of t / h; D cr is the cold reheat steam flow rate, with the unit of t / h; D gjs is the superheater desuperheating water flow rate, with the unit of t / h; D zjs is the reheater desuperheating water flow rate, with the unit of t / h; H m is the main steam enthalpy, with the unit of Kj / kg; H r is the reheater steam enthalpy, with the unit of Kj / kg; H fw is the feed water enthalpy, with the unit of Kj / kg; H cr is the cold reheat steam enthalpy, with the unit of Kj / kg; H gjs is the superheater desuperheating water enthalpy, with the unit of Kj / kg; H zjs is the reheater desuperheating water enthalpy, with the unit of Kj / kg; N cl is the power generation of the thermal power unit, with the unit of KW;

[0090] Since each parameter is related to the temperature and pressure of the working medium, the basic physical quantities and thermodynamic cycle parameters determined are:

[0091] Main steam flow rate, main steam temperature and main steam pressure; reheater steam flow rate, reheater steam temperature and reheater steam pressure; feed water flow rate, feed water flow rate temperature and feed water flow rate pressure; cold reheat steam flow rate, cold reheat steam temperature and cold reheat steam pressure; superheater desuperheating water flow rate, superheater desuperheating water temperature and superheater desuperheating water pressure; reheater desuperheating water flow rate, reheater desuperheating water temperature and reheater desuperheating water pressure.

[0092] In this embodiment, the sequential correction of each parameter value of the thermal power unit includes:

[0093] Measuring the time T required for each parameter measuring instrument of the thermal power unit to transmit parameters to the DCS channel through an oscilloscope yb , checking the inertia time parameter T set in the DCS preprocessing g , measuring the time difference T of parameter transmission between different DPU of the DCS through an SOE measuring instrument w, by checking the operation cycle and function block sequence of the DCS configuration page, the cycle time T of the configuration calculation is obtained p , the delay time T of the j-th parameter required for the measuring instrument parameters from the measuring instrument to the heat rate calculation function page can be obtained j :

[0094] T j = T yb + T g + T w + T p

[0095] After obtaining the delay times of all parameters, the maximum delay time T of the transmission times of all parameters is taken jmax , T jmax is subtracted from T j to obtain the compensation time T of each parameter j1 :

[0096] T j1 = T jmax - T j

[0097] Among them, T j1 is the compensation time of the j-th parameter, T jmax is the maximum delay time of the transmission times of all parameters, and T j is the delay time of the j-th parameter;

[0098] By performing timing correction for pure delay on the j-th parameter, it is ensured that all parameters are at the same timing. The correction formula is as follows:

[0099] Signal(X j1 ) = Signal(X j ) + delay(T j1 )

[0100] Among them, Signal(X j1 ) is the parameter signal after the j-th timing correction, Signal(X j ) is the parameter signal before the j-th timing correction, and delay(T j1 ) is the delay signal of the j-th parameter.

[0101] In this embodiment, the calculation steps of the sliding pressure curve calculation model for weighted timing energy balance under all operating conditions include:

[0102] Based on the respective parameter values of the thermal power unit after timing correction, judge the operating state of the thermal power unit, whether it is a steady-state condition or a dynamic condition;

[0103] When the thermal power unit is in a stable operating condition, substitute the parameter values of the thermal power unit after time series correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit;

[0104] When the thermal power unit is in a dynamic operating condition, use the feed water flow rate of the thermal power unit to perform dynamic time series correction on the main steam flow rate of the thermal power unit. Substitute the dynamically time series corrected main steam flow rate and the parameter values of the thermal power unit into the heat rate calculation formula to obtain the equivalent heat rate under dynamic conditions; perform dynamic weighted time series correction on the main steam pressure of the thermal power unit to obtain the equivalent main steam pressure of the thermal power unit; combine the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve;

[0105] Perform weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments.

[0106] Example 3

[0107] Please refer to Appendix Figure 1 , Figure 1 A sliding pressure curve calculation method for weighted time series energy balance under all operating conditions provided by an embodiment of the present invention includes:

[0108] S1: Determine the basic physical quantities and thermodynamic cycle parameters according to the actual requirements of heat rate calculation, and measure the parameter values of the thermal power unit;

[0109] S2: Perform time series correction on the parameter values of the thermal power unit;

[0110] S3: Input the parameter values of the thermal power unit after time series correction into the sliding pressure curve calculation model for weighted time series energy balance under all operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit;

[0111] S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve.

[0112] See Figure 2 , Figure 2 shows a schematic diagram of the calculation process of the sliding pressure curve calculation model for weighted time series energy balance under all operating conditions. The calculation steps of the sliding pressure curve calculation model for weighted time series energy balance under all operating conditions include:

[0113] Based on the parameter values of the thermal power unit after time series correction, judge the operating state of the thermal power unit, whether it is a steady-state condition or a dynamic condition;

[0114] When the thermal power unit is in a stable operating condition, substitute the parameter values of the thermal power unit after time series correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit;

[0115] When the thermal power unit is in a dynamic operating condition, use the feed water flow rate of the thermal power unit to perform dynamic time series correction on the main steam flow rate of the thermal power unit. Substitute the main steam flow rate of the thermal power unit after dynamic time series correction and the parameter values of the thermal power unit into the heat rate calculation formula to obtain the equivalent heat rate under dynamic conditions; perform dynamic weighted time series correction on the main steam pressure of the thermal power unit to obtain the equivalent main steam pressure of the thermal power unit; combine the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve;

[0116] Perform weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments.

[0117] In this embodiment, based on the parameter values of the thermal power unit after time series correction, judge the operating state of the thermal power unit, whether it is in a steady state or a dynamic state, including:

[0118] Calculate the maximum change rate of each parameter of the thermal power unit according to the parameter values of the thermal power unit after time series correction. The calculation method of the maximum change rate of each parameter of the thermal power unit is:

[0119]

[0120] Among them, K(t) imax is the maximum change rate of the i-th parameter of the thermal power unit; K id is the change rate correction coefficient of the i-th parameter to ensure that the change rates of each parameter of the thermal power unit are in the same dimension; x(t) i is the actual value of the i-th parameter at time t;

[0121] Compare the maximum change rate of each parameter of the thermal power unit with the steady-state condition judgment value. If K(t) imax ≤K1 and the actual load command before CCS speed limit has no change, then the thermal power unit is in a steady state; if there is K(t) imax >K1 and the actual load command before CCS speed limit has a step change, then the thermal power unit is in a dynamic state.

[0122] In this embodiment, using the feed water flow rate of the thermal power unit to perform dynamic time series correction on the main steam flow rate of the thermal power unit includes:

[0123] See Figure 3 , Figure 3Shows a schematic diagram of the step response curves of the main steam flow and the main feed water flow. The thermal power unit quickly responds to the AGC load command by opening the high-pressure control valve to increase the main steam flow. After the main steam flow increases, the main feed water flow increases, resulting in a deviation between the main steam flow and the main feed water flow. Therefore, the dynamic time series correction of the main steam flow of the thermal power unit is as follows:

[0124] Signal(D fw1 ) = Signal(D fw ) + delay(T d )

[0125] Where, Signal(D fw1 ) is the main steam flow signal of the thermal power unit after dynamic time series correction, Signal(D fw ) is the main steam flow signal of the thermal power unit, and delay(T d ) is the lag signal of the main steam flow of the thermal power unit relative to the feed water flow of the thermal power unit.

[0126] Optionally, the main steam flow D of the thermal power unit fw lags behind the feed water flow D of the thermal power unit m , and the lag time T d , T d can be obtained by the least squares method at different load points N ei and different load increase rates P ei :

[0127] T d = f([N ei , P ei )

[0128] Where, N ei is the i-th load point, and its range is (50% - 100%)N e ; P ei is the i-th load increase rate.

[0129] In this embodiment, the weighted time series correction of the main steam pressure of the thermal power unit includes: through the fuel - main steam pressure response test, obtaining the change amount ΔP of the main steam pressure when the fuel changes by 3 tons T ;

[0130] In the initial stage of load increase, due to the boiler heat storage, the pressure deviation is small; in the middle stage of load increase, the boiler heat storage decreases, and the dynamically increased coal quantity has not yet generated energy, so the pressure deviation is the largest; in the later stage of load increase, the dynamically increased coal quantity has already generated energy, and the pressure deviation decreases; therefore, during the load increase period, the weighted time series corrected main steam pressure is:

[0131]

[0132]

[0133] During the load reduction period, the main steam pressure after weighted time series correction is:

[0134]

[0135]

[0136] Among them, P T is the main steam pressure after weighted time series correction, with the unit of MPa; P ST is the real-time value of the main steam pressure, with the unit of MPa; θ is the correction weight value at different times during the load increase stage; n is the dynamically increased coal quantity, with the unit of ton; the time range of t is affected by the operating state of the thermal power unit.

[0137] In this embodiment, substituting the parameter values of the thermal power unit after time series correction into the heat rate calculation formula, the steady-state heat rate - main steam pressure curve of the thermal power unit is determined, including:

[0138] Processing the parameter values of the thermal power unit after time series correction by using the least square method and the heat rate calculation formula, the steady-state heat rate - main steam pressure curve f1(HR - P T ) is obtained.

[0139] Combining the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve, including:

[0140] Using the least square method to determine the dynamic main steam pressure curve f2(Hr - P T ) for the equivalent heat rate and the equivalent main steam pressure.

[0141] In this embodiment, performing a weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve for different load segments, including:

[0142] Under steady-state conditions, since the parameters of the thermal power unit are stable, the obtained steady-state heat rate - main steam pressure curve is relatively accurate and has a heavier weight; under dynamic conditions, due to load increase and decrease, since the parameters of the thermal power unit are constantly changing, its weight is lighter, and the faster the dynamic load changes, the higher the uncertainty of the heat rate - main steam pressure curve under dynamic conditions and the lighter the weight;

[0143] f(HR - P T ) = αf1(HR - P T ) + βf2(HR - P T )

[0144] Among them, f(HR - PT ) is the heat rate - main steam pressure curve, α is the weight of the heat rate - main steam pressure curve under steady-state conditions; β is the weight of the heat rate - main steam pressure curve under dynamic conditions.

[0145] In this embodiment, determining the final sliding pressure curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule includes:

[0146] By analyzing the heat rate - main steam pressure curves of different load segments, according to the lowest heat rate rule, the optimal load - main steam curve is determined to obtain the final sliding pressure curve.

[0147] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A sliding pressure curve calculation method for weighted time-series energy balance under all operating conditions, characterized in that Including: S1: Determine the basic physical quantities and thermal cycle parameters according to the actual requirements calculated by the heat rate, and measure the parameter values of each part of the thermal power unit; S2: Perform time series correction on the parameter values of each part of the thermal power unit; S3: Input the parameter values of the thermal power unit after time series correction into the sliding pressure curve calculation model of weighted time series energy balance under full operating conditions in sequence to obtain the heat rate - main steam pressure curve of the thermal power unit; Wherein: The calculation steps of the sliding pressure curve calculation model of weighted time series energy balance under full operating conditions include: Judge the operating state of the thermal power unit based on the parameter values of the thermal power unit after time series correction, whether it is a steady-state condition or a dynamic condition; When the thermal power unit is in a stable condition, substitute the parameter values of the thermal power unit after time series correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit; When the thermal power unit is in a dynamic condition, perform dynamic time series correction on the main steam flow of the thermal power unit using the feed water flow of the thermal power unit, substitute the main steam flow of the thermal power unit after dynamic time series correction and the parameter values of the thermal power unit into the heat rate calculation formula to obtain the equivalent heat rate under dynamic conditions; perform dynamic weighted time series correction on the main steam pressure of the thermal power unit to obtain the equivalent main steam pressure of the thermal power unit; determine the dynamic heat rate - main steam pressure curve by combining the equivalent heat rate and the equivalent main steam pressure; Perform weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve in different load sections; S4: Determine the load - main steam curve according to the heat rate - main steam pressure curve of the thermal power unit according to the lowest heat rate rule to obtain the final sliding pressure curve.

2. The method for calculating the sliding pressure curve of a weighted time-series energy balance under all operating conditions according to claim 1, characterized in that, The determination of the basic physical quantities and thermal cycle parameters according to the actual requirements calculated by the heat rate includes: The method for calculating the heat rate is: Among them, HR is the heat rate, with the unit of KJ / KWh; D m is the main steam flow rate, with the unit of t / h; D r is the reheater steam flow rate, with the unit of t / h; D fw is the feed water flow rate, with the unit of t / h; D cr is the cold reheat steam flow rate, with the unit of t / h; D gjs is the attemperating water flow rate of the superheater, with the unit of t / h; D zjs is the attemperating water flow rate of the reheater, with the unit of t / h; H m is the main steam enthalpy, with the unit of Kj / kg; H r is the reheater steam enthalpy, with the unit of Kj / kg; H fw is the feed water enthalpy, with the unit of Kj / kg; H cr is the cold reheat steam enthalpy, with the unit of Kj / kg; H gjs is the attemperating water enthalpy of the superheater, with the unit of Kj / kg; H zjs is the attemperating water enthalpy of the reheater, with the unit of Kj / kg; N cl is the generating power of the thermal power unit, with the unit of KW; Since each parameter is related to the temperature and pressure of the working medium, the determined basic physical quantities and thermal cycle parameters are: Main steam flow, main steam temperature and main steam pressure; reheater steam flow, reheater steam temperature and reheater steam pressure; feed water flow, feed water flow temperature and feed water flow pressure; cold reheater flow, cold reheater temperature and cold reheater pressure; superheater desuperheating water flow, superheater desuperheating water temperature and superheater desuperheating water pressure; reheater desuperheating water flow, reheater desuperheating water temperature and reheater desuperheating water pressure.

3. The sliding pressure curve calculation method for weighted time-sequence energy balance under all operating conditions according to claim 1, wherein The time series correction of the parameter values of each part of the thermal power unit includes: The time T required for the measurement instrument parameters of each parameter of the thermal power unit measured by the oscilloscope to be transmitted to the DCS channel yb , check the inertia time parameter T set in the DCS preprocessing g , measure the time difference T of parameter transmission between different DPUs of the DCS through the SOE measuring instrument w , obtain the cycle time T of the configuration calculation by checking the operation cycle and function block sequence of the DCS configuration page p , the jth parameter delay time T required for the measurement instrument parameters from the measurement instrument to the heat rate calculation function page can be obtained j as follows: T j = T yb + T g + T w + T p After obtaining the delay times of all parameters, take the maximum delay time T of the transmission times of all parameters j max , take T j max and T j to get the compensation time T for each parameter by taking the difference j1 : T j1 = T j max -T j Among them, T j1 is the compensation time for the j-th parameter, T j max is the maximum delay time of the transmission time of all parameters, T j is the delay time of the j-th parameter; Perform time series correction with pure delay on the jth parameter to ensure that all parameters are at the same time series. The correction formula is as follows: Signal(X j1 ) = Signal(X j ) + delay(T j1 ) Among them, Signal(X j1 ) is the parameter signal after the j-th timing correction, Signal(X j ) is the parameter signal before the j-th timing correction, and delay(T j1 ) is the delay signal of the j-th parameter.

4. A sliding pressure curve calculation method for weighted time-sequence energy balance under all operating conditions according to claim 1, characterized in that The judgment of the operating state of the thermal power unit based on the parameter values of the thermal power unit after time series correction, whether it is a steady-state condition or a dynamic condition includes: Calculate the maximum change rate of each parameter of the thermal power unit according to the parameter values of the thermal power unit after time series correction. The calculation method of the maximum change rate of each parameter of the thermal power unit is: where, K(t) imax is the maximum rate of change of the i-th parameter of the thermal power unit; K id is the rate of change correction coefficient of the i-th parameter to ensure that the rates of change of each parameter of the thermal power unit are in the same dimension; x(t) i is the actual value of the i-th parameter at time t; Compare the maximum change rates of each parameter of the thermal power unit with the steady-state condition judgment value. If all have K(t) imax ≤K1 and the actual load command before CCS speed limit has no change, then the thermal power unit is in the steady-state condition; if there is K(t) imax >K1 and the actual load command before CCS speed limit has a step change, then the thermal power unit is in the dynamic condition.

5. The sliding pressure curve calculation method for weighted time-sequence energy balance under all operating conditions according to claim 1, wherein The dynamic time series correction of the main steam flow of the thermal power unit using the feed water flow of the thermal power unit includes: The thermal power unit quickly responds to the AGC load command by opening the high-pressure control valve to increase the main steam flow. After the main steam flow increases, the main feed water flow increases, resulting in a deviation between the main steam flow and the main feed water flow. Therefore, the dynamic time-series correction of the main steam flow of the thermal power unit is as follows: Signal(D fw1 ) = Signal(D fw ) + delay(T d ) Among them, Signal(D fw1 ) is the main steam flow signal of the thermal power unit after the dynamic timing correction, Signal(D fw ) is the main steam flow signal of the thermal power unit, and delay(T d ) is the lag signal of the main steam flow of the thermal power unit relative to the feed water flow of the thermal power unit.

6. The sliding pressure curve calculation method of weighted time-sequence energy balance under all operating conditions according to claim 1, characterized in that The weighted time-series correction of the main steam pressure of the thermal power unit includes: Through the fuel - main steam pressure response test, the change in the main steam pressure ΔP corresponding to a 3 - ton change in fuel is obtained T ; In the initial stage of load increase, due to the heat storage of the boiler, the pressure deviation is small; in the middle stage of load increase, the heat storage of the boiler decreases, and the dynamically increased coal quantity has not yet generated energy, so the pressure deviation is the largest; in the later stage of load increase, the dynamically increased coal quantity has generated energy, and the pressure deviation decreases. Therefore, during the load increase period, the main steam pressure after weighted time-series correction is: During the load decrease period, the main steam pressure after weighted time-series correction is: Among them, P T is the main steam pressure after weighted time series correction, with the unit of MPa; P ST is the real-time value of the main steam pressure, with the unit of MPa; θ is the correction weight value at different times during the load increase stage; n is the dynamically increased coal quantity, with the unit of ton; the time range of t is affected by the operating state of the thermal power unit.

7. The method for calculating a sliding pressure curve of weighted time series energy balance under all operating conditions according to claim 1, wherein Including: Substituting the parameter values of the thermal power unit after time-series correction into the heat rate calculation formula to determine the steady-state heat rate - main steam pressure curve of the thermal power unit includes: Using the least squares method and the heat rate calculation formula to process the parameter values of the thermal power unit after time series correction, the steady-state heat rate - main steam pressure curve f1(HR - P T ) is obtained; Combining the equivalent heat rate and the equivalent main steam pressure to determine the dynamic heat rate - main steam pressure curve includes: The least squares method is used to determine the dynamic main steam pressure curve f2(HR-P T ) for the equivalent heat rate and the equivalent main steam pressure.

8. A sliding pressure curve calculation method for weighted time-series energy balance under all operating conditions according to claim 7, characterized in that Performing a weighted average calculation on the steady-state heat rate - main steam pressure curve and the dynamic heat rate - main steam pressure curve to determine the heat rate - main steam pressure curve of different load segments includes: Under steady-state conditions, since the parameters of the thermal power unit are stable, the obtained steady-state heat rate - main steam pressure curve is relatively accurate and has a heavier weight; under dynamic conditions, due to load increase and decrease, the parameters of the thermal power unit are constantly changing, so its weight is lighter, and the faster the dynamic load changes, the higher the uncertainty of the heat rate - main steam pressure curve under dynamic conditions and the lighter the weight; f(HR-P T ) = αf1(HR-P T ) + βf2(HR-P T ) where f(HR-P T ) is the heat rate - main steam pressure curve, α is the weight of the heat rate - main steam pressure curve under steady-state conditions; β is the weight of the heat rate - main steam pressure curve under dynamic conditions.

9. The method for calculating a sliding pressure curve of weighted time-sequence energy balance under all operating conditions according to claim 8, wherein Determining the final sliding pressure curve according to the heat rate - main steam pressure curve of the thermal power unit according to the minimum heat rate rule includes: By analyzing the heat rate - main steam pressure curve of different load segments, according to the minimum heat rate rule, determining the optimal load - main steam curve to obtain the final sliding pressure curve.

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