1. A thermal power generating unit double-machine combined heat supply control method is characterized in that a double-machine combined heat supply system is adopted, the double-machine combined heat supply system comprises a steam turbine unit A and a steam turbine unit B, and the method specifically comprises the following steps:

a steam flow distribution acquisition step: acquiring field real-time measuring point data, and calculating the regenerative steam extraction quantity of each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

and (3) predicting the maximum heating capacity: predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the double units;

selecting an optimal heating mode: respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode, and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

current heating mode confirmation step: determining a current heat supply mode according to the opening and closing state of a valve in a pipeline;

judging an optimal heat supply mode: judging whether the current heat supply mode is the optimal heat supply mode or not, and if not, switching the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, entering a heating mode optimization step;

a heating mode optimization step: comparing whether the absolute value of the difference value between the real-time heat supply network water supply temperature and the heat load required water supply temperature exceeds a preset starting optimization threshold value or not, if so, optimizing heat supply parameters according to the current heat supply mode, and if the absolute value is smaller than the preset stopping optimization threshold value, stopping the optimization of the operation parameters;

and carrying out the steps in a timed cycle.

2. The thermal power generating unit double-machine combined heat supply control method according to claim 1,

in the step of acquiring the steam flow distribution, the on-site real-time measuring points are an inlet and outlet pipeline of each cylinder and an inlet and outlet pipeline of a regenerative heater.

3. The thermal power generating unit double-machine combined heat supply control method according to claim 1,

the regenerative steam extraction quantity is calculated according to the following formula:

wherein h (·,. cndot.) represents the enthalpy of the substance at the corresponding temperature and pressure, P₀And P₂Indicating the corresponding position pressure, T₀～T₃Indicating the corresponding location temperature; d represents the heating circulation water flow rate, and η represents the heater efficiency.

4. The thermal power generating unit double-machine combined heat supply control method according to claim 1,

in the maximum heating capacity prediction step, the method for calculating the maximum heating capacity of the heating mode is as follows:

Q_maxi＝a_i·M₁+b_i·M₂+c_i (2)

in the formula, Q_maxiRepresenting the real-time maximum heating capacity of the mode i; m₁Representing the main steam quantity of the steam turbine set A; m₂Representing the main steam quantity of the steam turbine set B; a is_i、b_iAnd c_iAnd (4) representing the calculation coefficient of the variable working condition offline fitting of the thermodynamic system under different boiler loads.

5. The thermal power generating unit double-machine combined heat supply control method according to claim 1,

the maximum heating capacity prediction step comprises 6 heating modes, which are specifically as follows:

a first heating mode: a high-backpressure heat supply mode of the steam turbine set A and a high-backpressure heat supply mode of the steam turbine set B;

and a second heating mode: a steam turbine set A steam extraction high back pressure heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and a heating mode III: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and (4) heating mode four: a steam extraction high-back-pressure heat supply mode of the steam turbine set A and a no-load and electric boiler heat supply mode of a low-pressure cylinder of the steam turbine set B;

and a heating mode is five: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B low-pressure cylinder no-load and electric boiler heat supply mode;

and a heating mode six: the steam turbine set A has a low-pressure cylinder no-load heat supply mode and a high-low bypass and electric boiler heat supply mode.

6. The thermal power generating unit double-machine combined heat supply control method according to claim 5,

in the heat supply mode optimization step, the method for optimizing each heat supply mode parameter is as follows:

the first mode and the second mode optimize the back pressure of the steam turbine:

Δp_cis an optimized quantity of back pressure, Δ p, of the turbine_cWhen the pressure is more than 0, the corresponding back pressure quantity is increased, delta p_cWhen less than 0, the corresponding back pressure amount, Δ p, is reduced_cThe calculation formula is as follows:

wherein h (-) denotes the enthalpy of the substance corresponding to the pressure, h (-) denotes the enthalpy of the substance corresponding to the temperature and the pressure, p_cIndicating the exhaust pressure of the low-pressure cylinder of the steam turbine, D_rIndicating return flow of heat supply network, p_curIndicating the real-time pressure of the supply water of the heat supply network, T_setIndicating the heat supply network supply water scheduling temperature, T_curRepresenting the real-time temperature of the water supply of the heat supply network, D_LinRepresenting the steam inlet flow of the low-pressure cylinder;

the second mode, the third mode, the fourth mode, the fifth mode and the sixth mode optimize the steam extraction flow by adjusting the opening of a butterfly valve for extracting steam from the five-section heating:

ΔD_extthe optimization quantity of the steam extraction flow is calculated according to the following formula:

in the formula, p_mainIndicating the pressure of the steam in the main pipe, T_mainIndicating the steam temperature, p, of the heat-supplying main pipe_hIndicating that the heat net is hydrophobicPressure of pump outlet main pipe, T_hRepresenting the temperature of the outlet main pipe of the heat supply network drainage pump.

7. A thermal power unit and double-machine combined heat supply control system is characterized in that the thermal power unit and double-machine combined heat supply control method of any one of claims 1 to 6 is adopted, and the thermal power unit and double-machine combined heat supply control method comprises the following steps:

the system comprises a steam flow distribution acquisition module, a maximum heat supply capacity prediction module, an optimal heat supply mode selection module, a current heat supply mode confirmation module, an optimal heat supply mode judgment module, a heat supply mode optimization module, a heat supply mode switching module and a timing module;

the steam flow distribution acquisition module is connected with the input end of the maximum heat supply capacity prediction module and is used for acquiring on-site real-time measuring point data and calculating the regenerative steam extraction at each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

the maximum heat supply capacity prediction module is connected with the input end of the optimal heat supply mode selection module and used for predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the two units;

the optimal heating mode selection module is connected with the input end of the current heating mode confirmation module and is used for respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

the current heat supply mode confirming module is connected with the input end of the optimal heat supply mode judging module and used for confirming a current heat supply mode according to the opening and closing state of a valve in the pipeline;

the first output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode optimizing module, the second output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode switching module and used for judging whether the current heat supply mode is the optimal heat supply mode or not, and if the current mode is not the optimal heat supply mode, the heat supply mode switching module switches the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, the heating mode optimization module optimizes the current heating mode;

the input end of the timing module is connected with the output end of the heat supply mode optimization module, and the output end of the timing module, the output end of the heat supply mode switching module and the input end of the steam flow distribution acquisition module share a common endpoint for executing heat supply control in a timing cycle manner.

Background

Guaranteeing heat supply has long been a significant civil engineering. With the continuous improvement of living standard of people, the demand for heat supply in winter is continuously increased, which puts forward higher requirements for heat supply of the cogeneration unit in winter. However, in the three north area, the installed capacity of the existing thermal power generating unit is large, the unit is restricted by 'fixing power with heat', the flexibility is seriously insufficient, the peak regulation capability is greatly reduced in the heat supply period, the difficulty degree of system peak regulation is further increased, and the problems of wind abandoning and light abandoning are further prominent. Therefore, on the basis of guaranteeing the civil heat supply in winter, how to improve the flexibility of the coal-fired thermal power plant, realize the further thermoelectric decoupling of the thermal power unit, improve the deep peak shaving capability of the unit, enable the thermal power plant to operate economically and efficiently, and is the technical problem which needs to be solved urgently by the current thermal power unit.

The existing thermoelectric decoupling modes comprise installation of a heat storage tank, configuration of an electric boiler, modification of an optical axis of a steam turbine and the like, but the methods have the problem of high modification investment cost. In addition to the above technology, "a low-pressure cylinder no-load transformation system" disclosed in publication No. CN212671876U, the system is mainly optimized and upgraded for the problems of poor atomization effect of desuperheating water, easy water erosion of low-pressure cylinder blades, and the like existing in the low-pressure cylinder no-load. The low-pressure cylinder has less investment for no-load heat supply transformation and better economical efficiency, but has the problems of incomplete thermoelectric decoupling, limited heat supply capacity improvement and the like. In addition, the method introduces steam into a heat supply network heater by using the high-low bypass system, so that a heat supply network steam source is not influenced by the electrical load of a unit any more, relatively thorough thermoelectric decoupling is realized, the heat supply capacity is improved to a great extent, but the problems of high energy, low use and poor economy exist. The methods have some defects and poor flexibility, and cannot meet the heat supply load requirements of each stage in the whole heat supply period.

Therefore, the method and the system for controlling the double-machine combined heat supply of the thermal power generating unit are provided to solve the difficulties in the prior art, and the problems to be solved by the technical personnel in the field are urgently needed.

Disclosure of Invention

In view of the above, the invention provides a thermal power unit double-machine combined heat supply control method and system, which can realize flexible heat supply control of a thermal power unit double-machine combined heat supply system, enable a whole plant to adapt to continuous changes of heat supply load demands, and realize maximization of economic benefits of the whole plant.

In order to achieve the purpose, the invention adopts the following technical scheme:

a thermal power generating unit double-machine combined heat supply control method adopts a double-machine combined heat supply system, comprises a steam turbine unit A and a steam turbine unit B, and specifically comprises the following steps:

a steam flow distribution acquisition step: acquiring field real-time measuring point data, and calculating the regenerative steam extraction quantity of each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

and (3) predicting the maximum heating capacity: predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the double units;

selecting an optimal heating mode: respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode, and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

current heating mode confirmation step: determining a current heat supply mode according to the opening and closing state of a valve in a pipeline;

judging an optimal heat supply mode: judging whether the current heat supply mode is the optimal heat supply mode or not, and if not, switching the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, entering a heating mode optimization step;

a heating mode optimization step: comparing whether the absolute value of the difference value between the real-time heat supply network water supply temperature and the heat load required water supply temperature exceeds a preset starting optimization threshold value or not, if so, optimizing heat supply parameters according to the current heat supply mode, and if the absolute value is smaller than the preset stopping optimization threshold value, stopping the optimization of the operation parameters;

and carrying out the steps in a timed cycle.

Preferably, in the step of acquiring the steam flow distribution, the on-site real-time measuring points are an inlet and outlet pipeline of each cylinder and an inlet and outlet pipeline of the regenerative heater.

Preferably, the regenerative extraction steam quantity is calculated according to the following formula:

wherein h (·,. cndot.) represents the enthalpy of the substance at the corresponding temperature and pressure, P₀And P₂Indicating the corresponding position pressure, T₀～T₃Indicating the corresponding location temperature; d represents the heating circulation water flow rate, and η represents the heater efficiency.

Preferably, in the maximum heating capacity prediction step, the maximum heating capacity of the heating mode is calculated as follows:

Q_maxi＝a_i·M₁+b_i·M₂+c_i (2)

in the formula, Q_maxiRepresenting the real-time maximum heating capacity of the mode i; m₁Representing the main steam quantity of the steam turbine set A; m₂Representing the main steam quantity of the steam turbine set B; a is_i、b_iAnd c_iAnd (4) representing the calculation coefficient of the variable working condition offline fitting of the thermodynamic system under different boiler loads.

Preferably, in the step of predicting the maximum heating capacity, the heating mode includes 6, specifically as follows:

a first heating mode: a high-backpressure heat supply mode of the steam turbine set A and a high-backpressure heat supply mode of the steam turbine set B;

and a second heating mode: a steam turbine set A steam extraction high back pressure heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and a heating mode III: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and (4) heating mode four: a steam extraction high-back-pressure heat supply mode of the steam turbine set A and a no-load and electric boiler heat supply mode of a low-pressure cylinder of the steam turbine set B;

and a heating mode is five: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B low-pressure cylinder no-load and electric boiler heat supply mode;

and a heating mode six: the steam turbine set A has a low-pressure cylinder no-load heat supply mode and a high-low bypass and electric boiler heat supply mode.

Preferably, in the heat supply mode optimization step, the method for optimizing each heat supply mode parameter is as follows:

the first mode and the second mode optimize the back pressure of the steam turbine:

Δp_cis an optimized quantity of back pressure, Δ p, of the turbine_cWhen the pressure is more than 0, the corresponding back pressure quantity is increased, delta p_cWhen less than 0, the corresponding back pressure amount, Δ p, is reduced_cThe calculation formula is as follows:

wherein h (-) denotes the enthalpy of the substance corresponding to the pressure, h (-) denotes the enthalpy of the substance corresponding to the temperature and the pressure, p_cIndicating the exhaust pressure of the low-pressure cylinder of the steam turbine, D_rIndicating return flow of heat supply network, p_curIndicating the real-time pressure of the supply water of the heat supply network, T_setIndicating the heat supply network supply water scheduling temperature, T_curRepresenting the real-time temperature of the water supply of the heat supply network, D_LinRepresenting the steam inlet flow of the low-pressure cylinder;

the second mode, the third mode, the fourth mode, the fifth mode and the sixth mode optimize the steam extraction flow by adjusting the opening of a butterfly valve for extracting steam from the five-section heating:

ΔD_extthe optimization quantity of the steam extraction flow is calculated according to the following formula:

in the formula, p_mainIndicating the pressure of the steam in the main pipe, T_mainIndicating the steam temperature, p, of the heat-supplying main pipe_hIndicating heatPressure of main pipe at outlet of net drainage pump, T_hRepresenting the temperature of the outlet main pipe of the heat supply network drainage pump.

A thermal power generating unit double-machine combined heat supply control system comprises:

the system comprises a steam flow distribution acquisition module, a maximum heat supply capacity prediction module, an optimal heat supply mode selection module, a current heat supply mode confirmation module, an optimal heat supply mode judgment module, a heat supply mode optimization module, a heat supply mode switching module and a timing module;

the steam flow distribution acquisition module is connected with the input end of the maximum heat supply capacity prediction module and is used for acquiring on-site real-time measuring point data and calculating the regenerative steam extraction at each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

the maximum heat supply capacity prediction module is connected with the input end of the optimal heat supply mode selection module and used for predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the two units;

the optimal heating mode selection module is connected with the input end of the current heating mode confirmation module and is used for respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

the current heat supply mode confirming module is connected with the input end of the optimal heat supply mode judging module and used for confirming a current heat supply mode according to the opening and closing state of a valve in the pipeline;

the first output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode optimizing module, the second output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode switching module and used for judging whether the current heat supply mode is the optimal heat supply mode or not, and if the current mode is not the optimal heat supply mode, the heat supply mode switching module switches the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, the heating mode optimization module optimizes the current heating mode;

the input end of the timing module is connected with the output end of the heat supply mode optimization module, and the output end of the timing module, the output end of the heat supply mode switching module and the input end of the steam flow distribution acquisition module share a common endpoint for executing heat supply control in a timing cycle manner.

According to the technical scheme, compared with the prior art, the invention provides a thermal power generating unit double-machine combined heat supply control method and system, wherein the thermal power generating unit double-machine combined heat supply control method comprises the following steps: the method has the advantages that multiple heat supply modes are designed based on the thermal power unit and double-machine combined heat supply system according to different heat supply load requirements in the whole heat supply period by combining multiple heat and power decoupling modes, the flexible heat supply control of the thermal power unit and double-machine combined heat supply system is realized by switching the heat supply modes and optimizing heat supply parameters, the flexibility of double-machine operation of the thermal power unit is improved on the basis of heat supply guarantee, and the economic benefit of the whole plant is obviously improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a flow chart of a thermal power generating unit dual-machine combined heat supply control method of the present invention;

FIG. 2 is a schematic diagram of heat supply of a single thermal power generating unit according to the present invention;

FIG. 3 is a schematic view of a thermal power generating unit dual-unit combined heating system according to the present invention;

FIG. 4 is a schematic structural diagram of a thermal power generating unit dual-machine combined heat supply control system according to the present invention;

wherein, 1-high pressure cylinder; 2-intermediate pressure cylinder; 3-low pressure cylinder; 4-a generator; 5-a boiler; 6-a condenser; 7-a condensate pump; 8-low pressure backheating system; 9-a deaerator; 10-a feed pump; 11-a high-pressure heat regenerative system; 12-main steam regulating valve; 13-high side relief valve; 14-low by-pass relief valve; 15-five sections of heating steam extraction butterfly valves; 16-a steam inlet valve of a heat supply network condenser; 17-reheat steam regulating valve; 18-a heating system; 21-turboset a; 22-a steam turbine group; 23-a heat supply network condenser Aw; 24-heat supply network condenser Bw; 25-an electric boiler; 26-heat supply network circulation pump; 27-spike heaters; 28-condensate system; 29-a heat exchange station; 30-high and low pressure bypass system.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, an embodiment of the present invention discloses a thermal power generating unit dual-engine combined heat supply control method, which adopts a dual-engine combined heat supply system including a steam turbine unit a and a steam turbine unit B, and specifically includes the following steps:

a steam flow distribution acquisition step: acquiring field real-time measuring point data, and calculating the regenerative steam extraction quantity of each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

and (3) predicting the maximum heating capacity: predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the double units;

selecting an optimal heating mode: respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode, and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

current heating mode confirmation step: determining a current heat supply mode according to the opening and closing state of a valve in a pipeline;

judging an optimal heat supply mode: judging whether the current heat supply mode is the optimal heat supply mode or not, and if not, switching the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, entering a heating mode optimization step;

a heating mode optimization step: comparing whether the absolute value of the difference value between the real-time heat supply network water supply temperature and the heat load required water supply temperature exceeds a preset starting optimization threshold value or not, if so, optimizing heat supply parameters according to the current heat supply mode, and if the absolute value is smaller than the preset stopping optimization threshold value, stopping the optimization of the operation parameters;

and carrying out the steps in a timed cycle.

In one embodiment, the specific steps of the method are performed in a cycle period of 500 ms.

In one embodiment, the measured point data in the steam flow distribution obtaining step is steam temperature and pressure data.

In one embodiment, in the step of obtaining the steam flow distribution, the on-site real-time measuring points are an inlet/outlet pipeline of each cylinder and an inlet/outlet pipeline of the regenerative heater.

In one embodiment, the regenerative extraction is calculated as follows:

wherein h (·,. cndot.) represents the enthalpy of the substance at the corresponding temperature and pressure, P₀And P₂Indicating the corresponding position pressure, T₀～T₃Indicating the corresponding location temperature; d represents the heating circulation water flow rate, and η represents the heater efficiency.

According to the mass balance principle, the steam flow distribution in the heating system is obtained by calculating from the outlet of the boiler backwards step by step.

In one embodiment, in the maximum heating capacity prediction step, the maximum heating capacity of the heating mode is calculated as follows:

Q_maxi＝a_i·M₁+b_i·M₂+c_i (2)

in the formula, Q_maxiRepresenting the real-time maximum heating capacity of the mode i; m₁Representing the main steam quantity of the steam turbine set A; m₂Representing the main steam quantity of the steam turbine set B; a is_i、b_iAnd c_iOff-line fitting for representing variable working conditions of thermodynamic system under different boiler loadsThe calculation coefficient of (2).

M₁And M₂The real-time measurement is obtained by a field DCS system.

In one embodiment, in the step of predicting the maximum heating capacity, the heating mode includes 6, which is as follows:

a first heating mode: a high-backpressure heat supply mode of the steam turbine set A and a high-backpressure heat supply mode of the steam turbine set B;

and a second heating mode: a steam turbine set A steam extraction high back pressure heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and a heating mode III: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B steam extraction high back pressure heat supply mode;

and (4) heating mode four: a steam extraction high-back-pressure heat supply mode of the steam turbine set A and a no-load and electric boiler heat supply mode of a low-pressure cylinder of the steam turbine set B;

and a heating mode is five: a steam turbine set A low-pressure cylinder no-load heat supply mode and a steam turbine set B low-pressure cylinder no-load and electric boiler heat supply mode;

and a heating mode six: the steam turbine set A has a low-pressure cylinder no-load heat supply mode and a high-low bypass and electric boiler heat supply mode.

In a specific embodiment, the specific contents of the on-off state of the heating mode valve in 6 are as follows:

the heat supply mode I is characterized in that the heat supply mode comprises a high-back-pressure heat supply mode of a steam turbine unit A and a high-back-pressure heat supply mode of a steam turbine unit B:

the main steam regulating valve, the reheat steam regulating valve and the steam inlet valve of the heat supply network condenser of the steam turbine set A are opened, the high-side pressure reducing valve, the five-section heating steam extraction butterfly valve and the low-side pressure reducing valve are closed, the steam turbine set A utilizes low-pressure cylinder exhaust steam to supply heat to a heat supply system, and the corresponding valve state and the heat supply mode of the steam turbine set B are the same as those of the steam turbine set A;

a heat supply mode II, a steam turbine unit A steam extraction high back pressure heat supply mode and a steam turbine unit B steam extraction high back pressure heat supply mode:

on the basis of the first heat supply mode, the valve opening degrees of five-section heating steam extraction butterfly valves of the steam turbine set A and the steam turbine set B are respectively adjusted and can be adjusted from 0 to L, wherein L is the valve opening degree corresponding to the minimum steam inlet amount of a low-pressure cylinder in the steam extraction high-back-pressure heat supply mode, the states of other valves are unchanged, and the steam turbine set A and the steam turbine set B both use steam extraction and low-pressure cylinder steam extraction to supply heat to a heat supply system;

a heat supply mode III, namely a low-pressure cylinder no-load heat supply mode of the steam turbine set A and a steam extraction high-back pressure heat supply mode of the steam turbine set B:

on the basis of the second heat supply mode, the opening degree of a five-section heating steam extraction butterfly valve of the steam turbine set A is adjusted to enable the opening degree of the valve to be equal to L, the safe operation of the low-pressure cylinder is guaranteed, a steam inlet valve of a heat supply network condenser of the steam turbine set A is closed, the states of other valves are unchanged, the low-pressure cylinder of the steam turbine set A supplies heat in a no-load mode, and the steam turbine set B supplies heat to a heat supply system by using steam extraction and low-pressure cylinder exhaust steam;

and a heat supply mode is four, wherein the steam extraction high back pressure heat supply of the steam turbine set A and the no-load of the low pressure cylinder of the steam turbine set B plus the heat supply mode of the electric boiler are as follows:

on the basis of the second heat supply mode, adjusting the opening of a five-section heating steam extraction butterfly valve of the steam turbine set B to ensure that the opening of the valve is equal to L1, wherein L1 is the opening of the valve corresponding to the minimum steam inlet quantity of the low-pressure cylinder in the no-load heat supply mode, ensuring the safe operation of the low-pressure cylinder, closing the steam inlet valve of a heat supply network condenser of the steam turbine set B, keeping the states of other valves unchanged, simultaneously opening an electric boiler to heat part circulating water, supplying heat by using steam extraction and low-pressure cylinder steam extraction of the steam turbine set A, and supplying heat by combining the no-load low-pressure cylinder of the steam turbine set B and the electric boiler;

a heat supply mode is five, the steam turbine set A low-pressure cylinder supplies heat in a no-load mode, and the steam turbine set A low-pressure cylinder supplies heat in a no-load mode and in a no-load mode plus an electric boiler mode:

on the basis of the fourth heat supply mode, the opening degree of a five-section heating steam extraction butterfly valve of the steam turbine set A is adjusted to enable the opening degree of the valve to be equal to L1, a steam inlet valve of a heat supply network condenser of the steam turbine set A is closed, the states of other valves are unchanged, a low-pressure cylinder of the steam turbine set A supplies heat in an idle load mode, and a low-pressure cylinder of the steam turbine set B supplies heat in an idle load mode and an electric boiler mode;

the heat supply mode is six, the no-load heat supply of the low-pressure cylinder of the steam turbine set A, the high-low bypass of the steam turbine set B and the heat supply mode of the electric boiler are as follows:

and on the basis of the fifth heat supply mode, a high-side pressure reducing valve and a low-side pressure reducing valve of the steam turbine set B are opened, the states of other valves are unchanged, the low-pressure cylinder of the steam turbine set A supplies heat in an idle load mode, and the high-side bypass and the low-side bypass of the steam turbine set B supply heat with the electric boiler in a combined mode.

In one embodiment, the current heat supply mode is determined according to the valve switch states of a main steam regulating valve, a high side pressure reducing valve, a low side pressure reducing valve, a five-section heating steam extraction butterfly valve, a steam inlet valve of a heat supply network condenser and the like of the steam turbine set A and the steam turbine set B.

In a specific embodiment, the 6 heating modes adopt a sequential control method to realize switching control between the modes, and the sequential control step includes all steps of switching any heating mode to any other heating mode, that is, switching back and forth between any two modes can be realized.

In one embodiment, in the heating mode optimizing step, the method for optimizing each heating mode parameter is as follows:

the first mode and the second mode optimize the back pressure of the steam turbine:

Δp_cis an optimized quantity of back pressure, Δ p, of the turbine_cWhen the pressure is more than 0, the corresponding back pressure quantity is increased, delta p_cWhen less than 0, the corresponding back pressure amount, Δ p, is reduced_cThe calculation formula is as follows:

wherein h (-) denotes the enthalpy of the substance corresponding to the pressure, h (-) denotes the enthalpy of the substance corresponding to the temperature and the pressure, p_cIndicating the exhaust pressure of the low-pressure cylinder of the steam turbine, D_rIndicating return flow of heat supply network, p_curIndicating the real-time pressure of the supply water of the heat supply network, T_setIndicating the heat supply network supply water scheduling temperature, T_curRepresenting the real-time temperature of the water supply of the heat supply network, D_LinRepresenting the steam inlet flow of the low-pressure cylinder;

the second mode, the third mode, the fourth mode, the fifth mode and the sixth mode optimize the steam extraction flow by adjusting the opening of a butterfly valve for extracting steam from the five-section heating:

ΔD_extthe optimization quantity of the steam extraction flow is calculated according to the following formula:

in the formula, p_mainIndicating the pressure of the steam in the main pipe, T_mainIndicating the steam temperature, p, of the heat-supplying main pipe_hRepresents the pressure of the heat supply network drainage pump outlet main pipe T_hRepresenting the temperature of the outlet main pipe of the heat supply network drainage pump.

In a specific embodiment, referring to fig. 2, the thermal power unit and dual-unit combined heating system according to the present invention has two identical turbine units for combined heating, where the configuration of a single unit includes: the system comprises a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a low-pressure cylinder 3, a generator 4, a boiler 5, a condenser 6, a condensate pump 7, a low-pressure heat recovery system 8, a deaerator 9, a water feed pump 10, a high-pressure heat recovery system 11, a main steam regulating valve 12, a high-side pressure reducing valve 13, a low-side pressure reducing valve 14, a five-section heating steam extraction butterfly valve 15, a heat supply network condenser steam inlet valve 16, a reheat steam regulating valve 17 and a heat supply system 18. A superheated steam outlet of the boiler 5 is connected with a steam inlet of the high-pressure cylinder 1 through a main steam regulating valve 12, a steam outlet of the high-pressure cylinder 1 is connected with a reheater inlet of the boiler 5, a superheated steam outlet of the boiler 5 is connected with a reheater inlet of the boiler 5 through a high-bypass reducing valve 13, a reheater outlet of the boiler 5 is connected with a steam inlet of the intermediate pressure cylinder 2 through a reheater regulating valve 17, and is connected with a heat supply system 18 through a low-bypass reducing valve 14; the steam outlet of the intermediate pressure cylinder 2 is connected with the steam inlet of the low pressure cylinder 3 and is connected with a heating system 18 through a five-section heating steam extraction butterfly valve 15; the steam outlet of the low pressure cylinder 3 is connected with a heat supply system 18 through a steam inlet valve of a heat supply network condenser 16 and is connected with a condenser 6; an outlet of the condenser 6 is connected with an inlet of a condensate pump 7, an outlet of the condensate pump 7 is connected with an inlet of a low-pressure heat recovery system 8, an inlet of the low-pressure heat recovery system 8 is connected with an inlet of a deaerator 9, an outlet of the deaerator 9 is connected with an inlet of a water feed pump 10, an outlet of the water feed pump 10 is connected with an inlet of a high-pressure heat recovery system 11, and an outlet of the high-pressure heat recovery system 11 is connected with an inlet of a boiler 5.

In one embodiment, referring to fig. 3, the thermal power generating unit dual-unit combined heating system includes: the system comprises a steam turbine unit A21, a steam turbine unit B22, a heat supply network condenser Aw 23, a heat supply network condenser Bw 24, an electric boiler 25, a heat supply network circulating pump 26, a peak heater 27, a condensed water system 28, a heat exchange station 29 and a high-low pressure bypass system 30. The outlet of the high-low pressure bypass system 30 of the steam turbine set B22 is connected with a five-section heat supply steam extraction outlet of the steam turbine set B22; the steam turbine set A21 is connected with a steam outlet of the five-section heat supply extraction of the steam turbine set B22, and then is connected with a steam inlet of a peak heater 27, and the steam outlet of the peak heater 27 is connected with a condensate system 28; a low-pressure cylinder exhaust steam outlet of the turbine unit A21 is connected with a steam inlet of a heat supply network condenser Aw 23, and a steam outlet of the heat supply network condenser Aw 23 is connected with a condensed water system 28; a steam exhaust outlet of a low-pressure cylinder of the turboset B22 is connected with a steam inlet of a heat supply network condenser Bw 24, and a steam outlet of the heat supply network condenser Bw 24 is connected with a condensed water system 28; an outlet of the heat exchange station 29 is connected with a circulating water inlet of a heat supply network condenser Aw 23, and a circulating water outlet of the heat supply network condenser Aw 23 is connected with a circulating water inlet of a heat supply network condenser Bw 24; a circulating water outlet of a heat supply network condenser Bw 24 is connected with an inlet of a heat supply network circulating pump 26 and is also connected with an inlet of an electric boiler 25; the outlet of the electric boiler 25 is connected with the inlet of a heat supply network circulating pump 26, and the outlet of the heat supply network circulating pump 26 is connected with the drainage inlet of a peak heater 27; the spike heater 27 drain outlet is connected to the heat exchange station 29 inlet.

Referring to fig. 4, the invention discloses a thermal power generating unit double-machine combined heat supply control system, which comprises:

the system comprises a steam flow distribution acquisition module, a maximum heat supply capacity prediction module, an optimal heat supply mode selection module, a current heat supply mode confirmation module, an optimal heat supply mode judgment module, a heat supply mode optimization module, a heat supply mode switching module and a timing module;

the steam flow distribution acquisition module is connected with the input end of the maximum heat supply capacity prediction module and is used for acquiring on-site real-time measuring point data and calculating the regenerative steam extraction at each stage on line according to the heat balance of the heater to obtain the steam flow distribution of the heat supply system;

the maximum heat supply capacity prediction module is connected with the input end of the optimal heat supply mode selection module and used for predicting the maximum heat supply capacity of each heat supply mode in real time according to the flow of the main steam of the two units;

the optimal heating mode selection module is connected with the input end of the current heating mode confirmation module and is used for respectively comparing the relationship between the maximum heating capacity and the heat load demand of each heating mode and selecting the mode with the minimum maximum heating capacity as the optimal heating mode from the heating modes meeting the heat load demand;

the current heat supply mode confirming module is connected with the input end of the optimal heat supply mode judging module and used for confirming a current heat supply mode according to the opening and closing state of a valve in the pipeline;

the first output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode optimizing module, the second output end of the optimal heat supply mode judging module is connected with the input end of the heat supply mode switching module and used for judging whether the current heat supply mode is the optimal heat supply mode or not, and if the current mode is not the optimal heat supply mode, the heat supply mode switching module switches the current heat supply mode to the optimal heat supply mode; if the current mode is the optimal heating mode, the heating mode optimization module optimizes the current heating mode;

the input end of the timing module is connected with the output end of the heat supply mode optimization module, and the output end of the timing module, the output end of the heat supply mode switching module and the input end of the steam flow distribution acquisition module share a common endpoint for executing heat supply control in a timing cycle manner.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention in a progressive manner. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.