Optimal dispatch method for power system considering electric-thermal coupling of carbon capture power plant and improvement of its operation flexibility

Abstract

The present application belongs to the technical field related to electrical engineering, and discloses a method for optimizing the dispatch of an electric power system taking into account the electric-thermal coupling of a carbon capture power plant and the improvement of its operational flexibility. The electric power system includes a carbon capture thermal power system, a renewable energy system, an electric boiler, and a heat storage device. The carbon capture thermal power system has a low-pressure cylinder zero-output transformation structure, a parallel steam extraction structure formed by a small back-pressure steam turbine and a pressure reducing valve. The optimization dispatch method includes: constructing an optimization dispatch model and solving it, outputting the optimal decision for dispatch, and the optimization dispatch model includes an objective function and constraints. The constraints include electric power conservation constraints, steam conservation constraints, and electric-thermal coupling constraints. The electric-thermal coupling constraints indicate that the total power of carbon capture thermal power and the steam consumption of carbon capture desorption are in the electric-thermal feasible domain. The above dispatch method can accurately reflect the carbon capture electric-thermal coupling relationship to improve the feasibility of dispatch. The two structural designs of auxiliary equipment and carbon capture thermal power can improve the flexibility of power system dispatch.

Description

Technical Field

[0001] The present application belongs to the technical field related to electrical engineering, and more specifically, relates to a method for optimizing the scheduling of a power system taking into account the electrical and thermal coupling of a carbon capture power plant and the improvement of its operational flexibility. Background Art

[0002] Thermal power plays an irreplaceable role in ensuring the safe and stable operation of new energy-based power systems. Transforming traditional thermal power generation is the optimal strategy for balancing energy security and low-carbon development. Carbon capture and storage (CCS) technology is a key component of this transition. Post-combustion carbon capture holds great potential due to its mature technology and ease of retrofit. As a theoretical foundation, the accuracy of the mathematical modeling of carbon capture thermal power generation will directly impact the accuracy of power system dispatch and operation.

[0003] Carbon capture involves three steps: absorption, desorption, and compression. Absorption and compression consume electricity, while desorption requires extracting steam from the generator's steam cycle, consuming significant amounts of heat. However, at lower power levels, the steam flow available for desorption is limited, and the corresponding carbon capture level is also subject to physical constraints. This is the electrical-thermal coupling relationship of carbon capture thermal power generation.

[0004] On the one hand, existing research usually ignores the limitations of carbon capture electric-thermal coupling, which will worsen the accuracy and feasibility of power system dispatch results. On the other hand, due to the existence of electric-thermal coupling, the operating flexibility of carbon capture thermal power is relatively low, and there is an urgent need to study flexibility improvement solutions suitable for carbon capture thermal power. Summary of the Invention

[0005] In response to the above-mentioned defects or improvement needs of the existing technology, the present application provides a power system optimization scheduling method that takes into account the electric-thermal coupling of carbon capture power plants and the improvement of their operating flexibility, with the aim of improving the accuracy and flexibility of power system optimization scheduling.

[0006] To achieve the above-mentioned objectives, according to one aspect of the present application, a method for optimizing and dispatching a power system is provided, wherein the power system includes a carbon capture thermal power system, a renewable energy system, and auxiliary equipment, wherein the carbon capture thermal power system includes a thermal power generation system and a carbon capture system, and the auxiliary equipment includes an electric boiler and a heat storage device, wherein the electric boiler is used to consume part of the electric energy of the thermal power generation system to generate steam, and the carbon capture system has a parallel steam extraction structure formed by a back-pressure steam turbine and a pressure reducing valve, wherein the steam extraction structure is used to directly extract steam from the thermal power generation system, and the steam extraction ratio of the back-pressure steam turbine and the pressure reducing valve in the parallel steam extraction structure is adjustable, and the thermal power generation system has a low-pressure cylinder zero-output modification structure to maximize the steam extraction of the steam extraction structure, and after the steam of the electric boiler and the steam of the steam extraction structure are merged, a portion of the steam flows to the heat storage device for heat storage, or is merged with the steam output by the heat storage device and provided to the carbon capture system for carbon desorption;

[0007] The optimization scheduling method includes: constructing an optimization scheduling model and solving it, and outputting the optimal decision for scheduling. The optimization scheduling model includes an objective function and constraints, wherein:

[0008] The objective function is to minimize the total cost of the power system;

[0009] The constraints include electric power conservation constraints, steam conservation constraints and electric-thermal coupling constraints;

[0010] The power conservation constraint indicates that the total power generation of the carbon capture thermal power system is equal to the sum of the power equivalently consumed by the throttling action of the steam extraction structure pressure reducing valve, the available power, and the power consumed by all electric boilers. The available power is the sum of the net output power of the carbon capture thermal power grid and the power absorbed and compressed by the carbon capture system.

[0011] The steam conservation constraint indicates that the desorption steam consumption of the carbon capture system is equal to the sum of the steam extraction capacity of the steam extraction structure, the steam supply capacity of the electric boiler, and the equivalent steam supply capacity of the heat storage device;

[0012] The electrothermal coupling constraint indicates that the electrothermal operation point of the carbon capture thermal power system is located in the electrothermal feasible region considering electrothermal coupling, and the electrothermal operation point is determined by the available electric power and the amount of steam obtained by the carbon capture system.

[0013] In some embodiments,

[0014] The electric power conservation constraint is expressed as:

[0015]

[0016] Where, is the total power generation of carbon capture thermal power system i at time t, is the equivalent electric power consumed by the throttling action of the pressure reducing valve in the parallel steam extraction structure of the carbon capture thermal power system i at time t, is the available electric power of carbon capture thermal power system i at time t, The electric power supplied by the carbon capture thermal power system i to the electric boiler j operating in conjunction with it at time t, N eb is the number of electric boilers operating in conjunction with the carbon capture thermal power system i.

[0017] In some embodiments,

[0018] The steam conservation constraint is expressed as:

[0019]

[0020] Where G i,t is the steam extraction capacity of the steam extraction structure i of the carbon capture thermal power system at time t, G i ' ,t is the desorption steam consumption of the carbon capture system in the carbon capture thermal power system i at time t, is the steam supply of electric boiler j operating in conjunction with carbon capture thermal power system i at time t, is the equivalent steam supply of the heat storage device q operating in conjunction with the carbon capture thermal power system i at time t, N hs is the number of thermal storage devices operating in conjunction with the carbon capture thermal power system i.

[0021] In some embodiments,

[0022] The electrothermal coupling constraint is expressed as:

[0023]

[0024] Where, is the total power generation of carbon capture thermal power system i at time t, are the available electric power of the carbon capture thermal power system i at the vertex k1 in area ABC1D and the amount of steam obtained by the carbon capture system, are the available electric power of the carbon capture thermal power system i at the end point k2 of line segment C2D2 and the amount of steam obtained by the carbon capture system, and are the coefficients to be decided, and Satisfy the constraints:

[0025]

[0026] Where, S LPzeroare binary variables. If the electric heating operation point of the carbon capture thermal power system i falls within the region ABC1D at time t, then Take 1, Take 0, if the electric heating operation point of the carbon capture thermal power system i falls on the line segment C2D2 at time t, then Take 1, Take 0, if the carbon capture thermal power system i is shut down, then Take 0, otherwise take 1, S LPzero is a variable representing whether the carbon capture thermal power system i adopts the low-pressure cylinder zero-output transformation. If the low-pressure cylinder zero-output transformation is adopted, S LPzero is 1, otherwise it is 0;

[0027] Among them, the region ABC1D∪C2D2 is the feasible domain considering electric-thermal coupling when the carbon capture thermal power system i adopts the low-pressure cylinder zero-output transformation but does not introduce auxiliary equipment and parallel steam extraction structure.

[0028] In some embodiments,

[0029] The constraints also include thermal power generation system ramp constraints, minimum startup time constraints, minimum shutdown time constraints, power system power balance constraints, electric boiler operation constraints, heat storage device operation constraints, carbon capture system operation constraints, and renewable energy grid-connected power constraints.

[0030] In some embodiments,

[0031] The objective function is expressed as:

[0032]

[0033] Where f is the total cost, The fuel costs of conventional thermal power generation and thermal power generation systems operating in conjunction with carbon capture systems are: are the start-up and shutdown costs of conventional thermal power and thermal power generation systems operating in conjunction with carbon capture systems; The cost of transporting and storing captured carbon dioxide; C C is the cost of carbon trading; Penalty costs for wind curtailment; The penalty cost for abandoning light.

[0034] In some embodiments,

[0035] Equivalent electrical power consumption of the throttling action of the pressure reducing valve in the parallel extraction structure at time t satisfy:

[0036]

[0037] Where S throttleis a variable representing whether the extraction structure adopts a parallel extraction structure formed by a back pressure turbine and a pressure reducing valve. If the parallel extraction structure is adopted, S throttle is 1, if only the steam turbine is used, it is 0, G i,t is the steam extraction capacity of the steam extraction structure of the carbon capture thermal power system i at time t, η LDST It is the power generation of the back-pressure steam turbine per unit steam volume.

[0038] According to another aspect of the present application, an electronic device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any of the above methods when executing the computer program.

[0039] According to another aspect of the present application, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of any of the above methods are implemented.

[0040] According to another aspect of the present application, a computer program product is provided, comprising a computer program or instructions, wherein when the computer program or instructions are executed by a processor, the steps of any of the above methods are implemented.

[0041] In general, compared with the prior art, the above technical solutions conceived by this application have the following beneficial effects on the power system optimization and dispatching method provided by this application:

[0042] 1. The power system optimization and scheduling method provided in this application adds an electric boiler and a heat storage device on the basis of a traditional power system. The electric boiler is used to consume part of the electric energy of the thermal power generation system to generate steam. The steam from the electric boiler is combined with the steam from the steam extraction structure, and either a portion of it flows to the heat storage device for heat storage, or it is combined with the steam output from the heat storage device and provided to the carbon capture system for carbon desorption. Since the electric boiler and the heat storage device are jointly operated with the carbon capture thermal power plant, the equivalent electric and thermal operation feasible domain can be expanded and a certain degree of electric and thermal decoupling can be achieved, thereby making the power system scheduling more flexible.

[0043] 2. The power system optimization scheduling method provided in this application establishes an optimization scheduling model and solves it to output the optimal scheduling decision. In the established optimization scheduling model, relevant constraints on electric power and steam are constructed, including electric power conservation constraints, steam conservation constraints and electric-thermal coupling constraints. The above constraints take into account the electric-thermal coupling relationship of carbon capture thermal power, making the model more accurate and improving the feasibility of power system optimization scheduling. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 is a schematic structural diagram of a power system in one embodiment;

[0045] Figure 2 is a schematic structural diagram of a carbon capture system in one embodiment;

[0046] Figure 3 Schematic diagram of a parallel steam extraction structure formed by a back-pressure steam turbine and a pressure reducing valve in one embodiment;

[0047] Figure 4 This is a comparison diagram of a feasible region determined by considering carbon capture electrothermal coupling and a feasible region determined without considering electrothermal coupling for a conventional power system in one embodiment;

[0048] Figure 5 This is an equivalent electric-thermal feasible region of a carbon capture thermal power plant-electric boiler-heat storage device complex considering electric-thermal coupling for the power system proposed in this application in one embodiment;

[0049] Figure 6 The network topology and electrical connection relationship of each unit of the six-node power system of carbon capture thermal power in one embodiment

[0050] Figure 7 This is a schematic diagram of the output of a wind power station and a photovoltaic power station and the total power load in a system in one embodiment;

[0051] Figure 8 These are the carbon capture thermal power operation results corresponding to scenario C-S0 and scenario R-S0 in one embodiment. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. In addition, the technical features involved in the various embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0053] Example 1

[0054] like Figure 1As shown is a structural schematic diagram of the power system in an embodiment of the present application, which includes a carbon capture thermal power system, a renewable energy system and auxiliary equipment. The carbon capture thermal power system includes a thermal power generation system and a carbon capture system. The auxiliary equipment includes an electric boiler and a heat storage device. The electric boiler is used to consume part of the electric energy of the thermal power generation system to generate steam. The carbon capture system has a parallel steam extraction structure. The steam extraction structure is used to directly extract steam from the thermal power generation system and the steam extraction ratio of the back pressure turbine and the pressure reducing valve in the parallel steam extraction structure is adjustable. After the steam of the electric boiler and the steam of the steam extraction structure are merged, either a part of it flows to the heat storage device for heat storage, or it is merged with the steam output by the heat storage device and provided to the carbon capture system for carbon analysis. At any time, the heat storage device is only in one of the two states of heat release or heat storage. The equivalent steam supply of the heat storage device can be a negative number, representing a heat storage process.

[0055] like Figure 2 The figure shows a schematic diagram of the structure of a carbon capture system in one embodiment. It is generally connected in series at the end of the flue gas duct of a thermal power generation system. The main components are an absorption tower, a regeneration tower, a reboiler, a lean liquid tank, and a rich liquid tank. The carbon capture system relies on the circulation of a chemical solution containing ethanolamine as a solute to enrich carbon dioxide from the relatively low-concentration thermal power flue gas. It is then compressed in a compression process and stored or transported to a carbon sink. The liquid storage carbon capture system can operate flexibly in an energy-shifting manner. The core components are the lean liquid tank and the rich liquid tank, which decouple the amount of carbon dioxide desorption from the amount of absorption. When the desorption amount exceeds the absorption amount, the lean liquid accumulates and the rich liquid is consumed. When the absorption amount exceeds the desorption amount, the rich liquid accumulates and the lean liquid is consumed. The energy-intensive desorption process can be more frequently performed during low-load periods of the power system through flexible liquid storage operation.

[0056] The desorption process is the most energy-consuming part in the operation of the carbon capture system, and it mainly relies on extracting steam from the steam cycle of the thermal power unit to provide heat. The main steam of the traditional single-extraction condensing carbon capture thermal power plant is split after the high-pressure cylinder and the medium-pressure cylinder do work. A part of it enters the low-pressure cylinder to continue to do work and then is discharged into the condenser. The other part is extracted from the extraction port between the medium-pressure cylinder and the low-pressure cylinder to provide heat. The extraction flow is controlled by the exhaust butterfly valve. This application carries out zero-output transformation of the low-pressure cylinder. In view of the technical limitation that the heating capacity of conventional extraction condensing units under the maximum heating condition is constrained by the minimum condensate volume of the low-pressure cylinder, the technical idea of ​​the zero-output transformation of the low-pressure cylinder is to cut off the steam inlet of the low-pressure cylinder to maximize the extraction volume. The zero-output transformation of the low-pressure cylinder is to connect a low-pressure cylinder cooling bypass and its auxiliary system in parallel on the basis of the original medium- and low-pressure connecting pipes. When the cooling bypass is completely blocked, the system operates in a traditional manner (this is the non-cylinder-cutting operating condition). When the intermediate- and low-pressure connecting pipes are completely blocked, only a small amount of low-pressure cylinder cooling steam is introduced through the low-pressure cylinder cooling bypass. At this time, almost all of the intermediate-pressure cylinder exhaust steam is used for extraction heat supply, and the extraction structure operates approximately at full backpressure conditions (this is the cylinder-cutting operating condition) to maximize the extraction steam capacity. Therefore, the low-pressure cylinder zero-output modification can maximize the extraction of steam generated by the thermal power generation system.

[0057] In one embodiment, the steam extraction structure is further designed. Figure 3 The figure shows a schematic diagram of the structure of the steam extraction structure designed in one embodiment of the present application. The steam extraction structure is a parallel steam extraction structure formed by a back-pressure steam turbine and a pressure reducing valve. The steam extraction ratio of the back-pressure steam turbine and the pressure reducing valve in the parallel steam extraction structure is adjustable. The steam pressure extracted by the steam extraction structure is usually greater than the steam conditions required for solvent regeneration and cannot directly enter the reboiler. Therefore, the steam is generally reduced in pressure within the steam extraction structure. The steam can be throttled by the pressure reducing valve, but it will cause more energy loss. A small back-pressure steam turbine solution is adopted, that is, the extraction steam first passes through the back-pressure steam turbine to reduce the pressure and the steam desuperheater, and then enters the reboiler to heat the solvent. Therefore, the back-pressure steam turbine can recover a part of the energy as electrical power output, thereby reducing the pressure and improving the energy utilization efficiency. Therefore, compared with the pressure reducing valve throttling design, the use of the back-pressure steam turbine makes the net output power of the thermal power generation system higher under the same desorption steam extraction volume. However, for power systems containing carbon capture thermal power and fluctuating renewable energy sources, sufficient peak-shaving capacity is required from the regulating power source during certain periods. Carbon capture thermal power using a pressure reducing valve throttling system can achieve lower net output to meet system demands. Therefore, this embodiment combines the advantages of two heating branch designs and designs a parallel structure. Based on the real-time needs of the power system, by controlling the three-way valve, it can achieve full pressure reducing valve throttling or back-pressure turbine operation. Alternatively, by controlling the ratio of steam from the extraction port passing through the two pressure reducing branches, the carbon capture thermal power can be continuously adjusted between pure pressure reducing valve throttling and pure back-pressure turbine operation, thereby expanding the feasible region of electric heating for carbon capture thermal power.

[0058] When optimizing power system dispatch based on the aforementioned power system, an optimization dispatch model is constructed and solved to output the optimal dispatch decision. The optimization dispatch model includes an objective function and constraints. The following describes the optimization dispatch model in detail.

[0059] Compared with traditional modeling, this application has electric power conservation constraints, steam conservation constraints and electrothermal coupling constraints. Through the above constraints, the system's electrothermal operating point can be placed in a feasible area that takes into account the electrothermal coupling relationship, thereby making the model more accurate and improving the feasibility of the scheduling results.

[0060] Among them, the electrothermal feasible domain can be directly calculated and determined based on the constructed system and system parameters, and whether or not to consider electrothermal coupling will result in different calculated feasible domains, such as Figure 4The figure shows a comparison of the feasible region determined for a conventional power system with and without carbon capture electrothermal coupling. This diagram illustrates the relationship between the available electric power of the thermal power generation system and the steam (equivalent steam) that the carbon capture system can capture. The point determined by the available electric power and equivalent steam is the electrothermal operating point, and the electrothermal feasible region represents the operational range of the electrothermal operating point. The available electric power is expressed as the sum of the net output electric power after carbon capture consumption and the electric power consumed by the carbon capture system—that is, the sum of the electric energy consumption during the absorption and compression processes and the net output power of the carbon capture thermal power generation. Region ABC1D in the figure represents the feasible region with electrothermal coupling considered, while region ABCD represents the feasible region without electrothermal coupling. In region ABC1D, boundary AB represents the range of variation in the available electric power of the thermal power generation system under pure condensing conditions, boundary BC1 represents the desorption heating condition when the boiler in the thermal power generation system maintains the minimum evaporation rate, boundary C1D represents the desorption heating condition when the minimum condensation rate of the low-pressure cylinder is reached, and boundary DA represents the desorption heating condition when the boiler maintains the maximum continuous evaporation rate. These boundaries together form the convex polygonal feasible region of the carbon capture thermal power generation system. The operating state of any point within the feasible region is represented by a linear combination of the vertices of the convex polygonal boundary. As can be seen from the figure, when considering electrothermal coupling, the maximum desorption steam extraction capacity is limited by the electric power. At this time, operating point C is actually a physically infeasible point. This shows that traditional modeling without considering electrothermal coupling will greatly overestimate the operational flexibility of carbon capture thermal power generation. However, considering electrothermal coupling can make the modeling more precise and accurate.

[0061] like Figure 5 The figure shows the electric-thermal feasible domain considering electric-thermal coupling for the power system proposed in this application, wherein the operating range ABC1D∪C2D2 shows the feasible operating range after the thermal power generation system adopts the low-pressure cylinder zero-output transformation. Specifically, the range ABC1D is the electric-thermal feasible domain of the thermal power generation system without the low-pressure cylinder zero-output transformation, and the line segment C2D2 is the additional area of ​​the feasible domain after the low-pressure cylinder zero-output transformation is added. If a parallel steam extraction structure is adopted and an electric boiler and a heat storage device are introduced, the operating range boundary under the low-pressure cylinder non-cut-cylinder operation condition is as follows: Figure 5 As shown by the short dash line, the operating range boundary under the low-pressure cylinder cutting operation condition is as follows Figure 5 The dotted line indicates the operating range under the comprehensive solution, thus the union of the area enclosed by the dashed line and the area enclosed by the dotted line. As can be seen from the figure, adding electric boilers and heat storage devices, as well as adopting a parallel steam extraction structure, can expand the feasible region of electric heating operation and make regulation more flexible.

[0062] Based on the construction of the feasible region, the constraints of this application include electric power conservation constraints, steam conservation constraints and electric-thermal coupling constraints.

[0063] The power conservation constraint states that the total power generation of the carbon capture thermal power system is equal to the sum of the power consumption equivalent to the throttling effect of the pressure reducing valve in the steam extraction structure, the available power, and the power consumed by all electric boilers. Specifically, it can be expressed as:

[0064]

[0065] Where, is the total power generation of carbon capture thermal power system i at time t, is the equivalent electric power consumed by the throttling action of the pressure reducing valve in the parallel steam extraction structure of the carbon capture thermal power system i at time t, is the available electric power of carbon capture thermal power system i at time t, The electric power supplied by the carbon capture thermal power system i to the electric boiler j operating in conjunction with it at time t, N eb is the number of electric boilers operating in conjunction with the carbon capture thermal power system i.

[0066] Among them, the equivalent electric power consumed by the throttling action of the pressure reducing valve in the steam extraction structure at time t can be controlled satisfy:

[0067]

[0068] Where S throttle It is a characterizing variable of whether the extraction structure adopts the parallel extraction design formed by the back pressure turbine and the pressure reducing valve. throttle is 1, otherwise (i.e. only using steam turbine) is 0, G i,t is the steam extraction capacity of the steam extraction structure i of the carbon capture thermal power system at time t, η LDST is the power generation of the back-pressure steam turbine per unit steam volume. This constraint states that when a low-back-pressure steam turbine extraction configuration is used, there is no energy loss due to throttling. However, when the parallel configuration described above is used, the equivalent power consumed by throttling in the pressure reducing valve branch must not exceed the power generated when all the extracted steam passes through the low-back-pressure steam turbine branch.

[0069] Among them, the net grid-connected output power of carbon capture thermal power (thermal power generation system + carbon capture system) Available electrical power The relationship is:

[0070]

[0071] Where, Absorbing process energy consumption for carbon capture systems, is the energy consumption of the compression process of the carbon capture system, which is calculated as:

[0072]

[0073] Where, The amount of carbon dioxide absorbed by the carbon capture system, is the amount of carbon dioxide desorbed by the carbon capture system, μ ab is the electrical energy consumption for absorbing unit amount of carbon dioxide, μ com It is the electrical energy consumption for compressing a unit amount of carbon dioxide.

[0074] The steam conservation constraint states that the steam consumption of the carbon capture system is equal to the sum of the steam extraction capacity of the steam extraction structure, the steam supply of the electric boiler, and the equivalent steam supply of the heat storage device. When the heat storage device receives steam, its equivalent steam supply is negative, and when the heat storage device outputs steam, its equivalent steam supply is positive. Specifically, it can be expressed as:

[0075]

[0076] Where G i,t is the steam extraction capacity of the steam extraction structure of the carbon capture thermal power system i at time t, G i ' ,t is the desorption steam consumption of the carbon capture system corresponding to the carbon capture thermal power system i at time t, is the steam supply of electric boiler j operating in conjunction with carbon capture thermal power system i at time t, is the equivalent steam supply of the heat storage device q operating in conjunction with the carbon capture thermal power system i at time t, N hs is the number of thermal storage devices operating in conjunction with the carbon capture thermal power system i.

[0077] The electric-thermal coupling constraint means that the electric-thermal operation point of the carbon capture thermal power system is located in the electric-thermal feasible region considering electric-thermal coupling. The electric-thermal operation point is determined by the available electric power and the amount of steam obtained by the carbon capture system. It can be expressed as:

[0078]

[0079] Where, is the total power generation of carbon capture thermal power system i at time t, are the available electric power of the carbon capture thermal power system i at the vertex k1 of the region ABC1D (the available electric power here is actually the total power generation of the carbon capture thermal power system i when no auxiliary equipment and parallel steam extraction structure are introduced) and the amount of steam obtained by the carbon capture system (the amount of steam here is actually the amount of steam extracted by the steam extraction structure when no auxiliary equipment and parallel steam extraction structure are introduced). are the available electric power of the carbon capture thermal power system i at the endpoint k2 of the line segment C2D2 (the available electric power here is actually the total power generation of the carbon capture thermal power system i when no auxiliary equipment and parallel steam extraction structure are introduced) and the steam volume obtained by the carbon capture system (the steam volume here is actually the steam volume extracted by the steam extraction structure when no auxiliary equipment and parallel steam extraction structure are introduced). and are the coefficients to be decided, and Satisfy the constraints:

[0080]

[0081] Where, S LPzero are binary variables. If the electric heating operation point of the carbon capture thermal power system i falls within the region ABC1D at time t, then Take 1, Take 0, if the electric heating operation point of the carbon capture thermal power system i falls on the line segment C2D2 at time t, then Take 1, Take 0, if the carbon capture thermal power system i is shut down, then Take 0, otherwise take 1, S LPzero is a variable representing whether the carbon capture thermal power system i adopts the low-pressure cylinder zero-output transformation. If the low-pressure cylinder zero-output transformation is adopted, S LPzero is 1, otherwise it is 0.

[0082] The above constraints make modeling more accurate. In addition to the above constraints, some conventional constraints for power system scheduling can also be constructed, such as thermal power generation system ramping constraints, minimum startup time constraints, minimum downtime constraints, power system power balance constraints, electric boiler operation constraints, thermal storage device operation constraints, carbon capture system operation constraints, and renewable energy grid-connected power constraints.

[0083] Climbing constraints:

[0084]

[0085] Where, is the pure condensing output of the unit when the steam extraction volume of the carbon capture thermal power system i at time t is all used for low-pressure cylinder steam injection and power generation, η LP is the power generation efficiency of the low-pressure cylinder, are the upper and lower ramp rate limits of carbon capture thermal power, They are the minimum and maximum technical outputs of carbon capture thermal power (thermal power generation system + carbon capture system) under pure condensation conditions without desorption process, The binary variables represent the start and stop status of the carbon capture thermal power plant in time periods t and t-1, respectively. 1 indicates start and 0 indicates stop.

[0086] Minimum startup / downtime constraints:

[0087]

[0088] Where, They represent the minimum startup and shutdown time of the thermal power generation system respectively, and T is the end time of the scheduling cycle.

[0089] Power system power balance constraints:

[0090]

[0091] Where N p is the number of conventional thermal power stations in the power system, N ccpp is the number of carbon capture thermal stations in the system, N w 、N s are the number of wind power stations and photovoltaic power stations respectively, is the power generation capacity of conventional thermal power, is the grid-connected power generation of wind power and photovoltaic power, D t is the total power load, The electric energy obtained by the electric boiler from the power grid.

[0092] Electric boiler operation constraints:

[0093]

[0094] Where, is the installed capacity of electric boiler; η eb is the electric-to-heat conversion efficiency of the electric boiler; k eb is the conversion factor of heat energy and steam flow.

[0095] Thermal storage device operation constraints:

[0096]

[0097] Where, To store / release heat for the heat storage device; The maximum rate at which heat is stored or released from the heat storage device; for its heat storage level; is heat loss; k hs is the conversion coefficient of heat storage device heat energy and steam flow.

[0098] Carbon capture system operation constraints:

[0099]

[0100] Where, is the maximum carbon capture rate; is the desorption capacity coefficient; k steam The amount of steam required to desorb a unit amount of carbon dioxide; is the volume of solution in the rich liquid tank and the lean liquid tank; The volume of solution required to absorb a unit amount of carbon dioxide; They respectively represent the carbon emission intensity at the operating boundary points of the carbon capture thermal power plant when the steam inlet to the low-pressure cylinder cannot be cut off and when the steam inlet to the low-pressure cylinder is cut off.

[0101] Renewable energy grid-connected power constraints:

[0102]

[0103] Where, are the maximum available power generation of the wind power station and photovoltaic power station in time period t respectively.

[0104] Other constraints include upper and lower limits on the heat storage capacity of the heat storage device, upper and lower limits on the volume of the liquid storage tank solution, the constraint that the heat storage capacity of the heat storage device and the volume of the liquid storage tank solution are equal throughout the scheduling period, power system reserve constraints, and DC power flow constraints.

[0105] The objective function of the optimization scheduling model is to minimize the total cost of the power system. It can be expressed as:

[0106]

[0107] Where f is the total cost, The fuel costs of conventional thermal power generation and thermal power generation systems operating in conjunction with carbon capture systems are: are the start-up and shutdown costs of conventional thermal power and thermal power generation systems operating in conjunction with carbon capture systems; The cost of transporting and storing captured carbon dioxide; C C is the cost of carbon trading; Penalty costs for wind curtailment; The penalty cost for abandoning light.

[0108] Fuel costs:

[0109]

[0110] Where T is the end time of the scheduling period, N p is the number of conventional thermal power stations in the power system, N ccpp is the number of carbon capture thermal power stations in the system. k1 and k2 represent the vertex numbers of the feasible region. correspond Figure 5 The combined coefficients of the vertices of the boundary of the running interval ABC1D, is the running cost of the corresponding vertex; The corresponding Figure 5 The combination coefficient of the cylinder cutting operation range boundary C2D2 after the low-pressure cylinder zero output transformation is adopted. is the running cost of the corresponding vertex. Since the running boundary after cutting the cylinder is the back pressure line, The vertex dimension is 2. is the power generation output of conventional thermal power during period t, The coal consumption cost per unit of electricity generated by conventional thermal power generation.

[0111] Start-stop costs:

[0112]

[0113] Where, are the start-up and shutdown costs of conventional thermal power and carbon capture thermal power, respectively; It is a binary variable representing the start and stop status of conventional thermal power in the period t and t-1, 1 means start, and 0 means stop.

[0114] Costs of transporting and storing captured CO2:

[0115]

[0116] Where, is the amount of carbon dioxide accumulated during the desorption process of carbon capture thermal power generation period t, c T&S is the transportation and storage cost per unit amount of carbon dioxide.

[0117] Carbon emission rights trading costs

[0118] C C =π C (E p +E ccpp -M C -E B )

[0119] Where, E p represents the carbon emissions of conventional thermal power, E ccpp Indicates the carbon dioxide content in the flue gas of carbon capture thermal power plants, M C Indicates the carbon capture capacity of carbon capture thermal power generation, E B represents the carbon emission quota of the system, π C E is the price coefficient of the carbon emission trading market. p 、E ccpp 、M C The calculation formula is as follows:

[0120]

[0121]

[0122] In the above formula, δp Represents the carbon emission intensity of conventional thermal power.

[0123] Penalty costs for curtailing renewable energy:

[0124]

[0125] Where ω w 、ω s are the penalty coefficients for wind and solar curtailment, respectively.

[0126] Solve the above-mentioned optimization scheduling model and output the optimal scheduling decision. In one embodiment, the decision variables specifically include the start-stop status of the carbon capture thermal power plant, the cylinder cutting operation status, the convex combination coefficient of the electric-thermal coupling constraint, the equivalent electric power consumption of the throttling effect of the pressure reducing valve; the start-stop status and output of conventional thermal power; the grid-connected output of wind power and photovoltaic power; the workload of the electric boiler; the storage / release power of the heat storage device; the absorption and desorption amount of the carbon capture system, etc.

[0127] Example 2

[0128] The present application also relates to an electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0129] The electronic device may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The processor may be a central processing unit (CPU), or other general-purpose processors, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The memory may be used to store computer programs and / or modules, and the processor may perform various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory.

[0130] Example 3

[0131] The present application also relates to a computer-readable storage medium having a computer program stored thereon, which implements the steps of the above method when the computer program is executed by a processor.

[0132] Specifically, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0133] Example 4

[0134] The present invention provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the steps of the method of the above-described embodiment of the present invention.

[0135] Example 5

[0136] Taking a six-node power system as an example, the effectiveness of the improved carbon capture modeling and comprehensive flexibility enhancement scheme considering electrical and thermal coupling proposed in this invention is verified.

[0137] The network topology of the six-node power system of the carbon capture thermal power plant and the electrical connection relationship of each unit are as follows: Figure 6 shown.

[0138] The system's generators include four conventional thermal power plants (G1, G2, G3, and G4), one carbon capture thermal power plant CCPP1, a wind farm W1, and a photovoltaic power plant PV1. G1, G2, and G3 have a capacity of 169 MW, with a minimum output of 45%. G4 has a capacity of 247 MW, with a minimum output of 40%. CCPP1 has a capacity of 247 MW. The vertices of its basic feasible operating range and the endpoints of its cylinder-cutting operation after the low-pressure cylinder zero-output modification are shown in Table 1.

[0139] Table 1 The vertices of the feasible region for carbon capture thermal power generation

[0140]

[0141]

[0142] The output of wind power station, photovoltaic power station and total power load in the system are as follows: Figure 7 As shown, the total load is evenly distributed between nodes 3 and 6. The parameters of the introduced external auxiliary equipment are preset as follows: the maximum operating electrical load of each electric boiler is 50MW; the maximum storage / release power of each heat storage device is 50MW, and the upper and lower limits of the heat storage level are 50MWh and 400MWh, respectively.

[0143] A total of five scenarios are set up for analysis:

[0144] Virtual scenario BAU: no carbon capture;

[0145] Baseline scenario C-S0: Carbon capture is performed, but electric-thermal coupling is not considered, the steam extraction structure does not adopt a parallel structure, and no low-pressure cylinder zero-output transformation, electric boiler, or heat storage device are introduced;

[0146] Improved scenario R-S0: Carbon capture is performed and electric-thermal coupling is considered, but the steam extraction structure does not adopt a parallel structure and does not introduce low-pressure cylinder zero-output modification, electric boilers, or heat storage devices;

[0147] Improvement scenario R-S1: Carbon capture is performed and electric-thermal coupling is considered. The steam extraction structure adopts a parallel structure, but no low-pressure cylinder zero-output modification, electric boiler, or heat storage device is introduced.

[0148] Improved scenario R-S2: Carbon capture is carried out and electric-thermal coupling is considered. The steam extraction structure adopts a parallel structure and introduces low-pressure cylinder zero-output transformation, electric boiler, and heat storage device.

[0149] Table 2 shows the operational optimization results for a total of five scenarios. In the table, the scenarios with a parallel extraction structure, zero-output low-pressure cylinder modification, electric boiler configuration, and heat storage are abbreviated as PRV, LPZ, EB, and HS, respectively. Both the EB and HS scenarios only have one auxiliary device. The three result indicators in Table 2 are the total system operating cost, the total amount of renewable energy curtailment during all periods, and the total net carbon emissions of the thermal power units during all periods.

[0150] Table 2 Scenario settings and main results of each scenario

[0151]

[0152] According to the data in Table 2 and the specific operating conditions of each scenario, it can be analyzed that the introduction of carbon capture has significantly improved the economic efficiency of system operation. Compared with the scenario BAU without carbon capture, the result indicators of the scenarios C-S0, R-S0, R-S1 and R-S2 with carbon capture have been improved, especially the scenario R-S2 proposed in this application, which has the lowest total cost. Comparing the results of R-S1 with those of R-S0 in Table 2, it can be seen that the proposed new carbon capture system steam extraction structure design can effectively reduce the total cost of the system and renewable power curtailment, verifying the effectiveness of the proposed structural design. Comparing the results of R-S2 with those of R-S0 in Table 2, it can be seen that the proposed comprehensive flexibility improvement plan can further reduce the total cost of the system, significantly reduce the renewable power curtailment and carbon emissions of the system, verifying the effectiveness of the comprehensive flexibility improvement plan.

[0153] Scenarios C-S0 and R-S0 analyze the effectiveness of the improved modeling approach that considers the electrothermal coupling of the carbon capture system. Scenario C-S0, which ignores electrothermal coupling, overestimates the operational flexibility of the carbon capture thermal power plant. Compared to the improved modeling results of scenario R-S0, which uses a precise flexibility description, the cost-based indicators (smaller indicators are better) for its operational optimization results are generally lower, presenting an overly optimistic idealized state of system operation. Because scenario C-S0 does not consider electrothermal coupling, its assessment of the carbon capture system's performance is overly optimistic, leading to distorted optimization results. In Table 2, compared to R-S0, C-S0 underestimates the total system operating cost by 157,500 yuan, a deviation of 4.66%. It also underestimates the system's renewable energy curtailment by 248.5 MWh, a deviation of 59.58%. It also underestimates the system's net carbon emissions by 769.86 tons, a deviation of 10.94%.

[0154] The root cause of the distortion of the optimization results of scenario C-S0 (traditional modeling) is that the simulated carbon capture thermal power operation state violates the actual electric-thermal coupling relationship constraints in some periods, and the electric-thermal operation point is outside the feasible region, which is referred to as the "infeasible point" below. Figure 8 As shown in the figure, in both comparison scenarios, the carbon capture thermal power operation results corresponding to scenario C-S0 have infeasible points. It should be noted that the origin corresponding to the shutdown state of the carbon capture thermal power is a special operating point rather than an infeasible point. The infeasible points of scenario C-S0 are all idealized steam extraction under the minimum main steam condition, corresponding to the carbon capture system operating at minimum main steam and maximum desorption capacity to maximize system absorption during the period of high wind power generation. However, the desorption steam supply capacity of the carbon capture thermal power is the weakest under the minimum main steam condition, and the idealized operating point of traditional modeling cannot be achieved in actual operation. Therefore, the actual renewable energy curtailment is far greater than the results of traditional modeling operation simulation. In addition, due to the existence of infeasible points, the optimized scheduling results under traditional modeling are not feasible in reality.

[0155] The technical features of the above embodiments can be combined in any combination. To keep the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be noted that the phrases "in one embodiment", "for example", "and another example" in this application are intended to illustrate this application and are not intended to limit this application.

[0156] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person skilled in the art could make numerous variations and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application.

Claims

1. A method for optimizing the dispatch of a power system considering the electric-thermal coupling of a carbon capture power plant and the improvement of its operational flexibility, characterized in that: The power system includes a carbon capture thermal power system, a renewable energy system and auxiliary equipment, the carbon capture thermal power system includes a thermal power generation system and a carbon capture system, the auxiliary equipment includes an electric boiler and a heat storage device, the electric boiler is used to consume part of the electric energy of the thermal power generation system to generate steam, the carbon capture system has a parallel steam extraction structure formed by a back pressure steam turbine and a pressure reducing valve, the steam extraction structure is used to directly extract steam from the thermal power generation system, and the steam extraction ratio of the back pressure steam turbine and the pressure reducing valve in the parallel steam extraction structure is adjustable, the thermal power generation system has a low pressure cylinder zero output transformation structure to maximize the steam extraction of the steam extraction structure, the steam of the electric boiler and the steam of the steam extraction structure are combined, or a part of them flows to the heat storage device for heat storage, or they are combined with the steam output by the heat storage device and provided to the carbon capture system for carbon desorption; The optimization scheduling method includes: constructing an optimization scheduling model and solving it, and outputting the optimal decision for scheduling. The optimization scheduling model includes an objective function and constraint conditions, wherein: The objective function is to minimize the total cost of the power system; The constraints include electric power conservation constraints, steam conservation constraints and electric-thermal coupling constraints; The power conservation constraint indicates that the total power generation of the carbon capture thermal power system is equal to the sum of the power equivalently consumed by the throttling effect of the pressure reducing valve of the extraction structure, the available power and the power consumed by all electric boilers. The available power is the sum of the net grid-connected output power of the carbon capture thermal power system and the power absorbed and compressed by the carbon capture system. The steam conservation constraint indicates that the desorption steam consumption of the carbon capture system is equal to the sum of the steam extraction amount of the steam extraction structure, the steam supply amount of the electric boiler and the equivalent steam supply amount of the heat storage device; The electric-thermal coupling constraint indicates that the electric-thermal operation point of the carbon capture thermal power system is located in the electric-thermal feasible region considering electric-thermal coupling, and the electric-thermal operation point is determined by the available electric power and the amount of steam obtained by the carbon capture system.

2. The power system optimization dispatching method according to claim 1, characterized in that: The electric power conservation constraint is expressed as: In the formula, is the total power generation of carbon capture thermal power system i at time t, is the equivalent electric power consumed by the throttling action of the pressure reducing valve in the parallel steam extraction structure of the carbon capture thermal power system i at time t, is the available electric power of carbon capture thermal power system i at time t, The electric power supplied by the carbon capture thermal power system i to the electric boiler j operating in conjunction with it at time t, N eb is the number of electric boilers operating in conjunction with the carbon capture thermal power system i.

3. The power system optimization dispatching method according to claim 1, characterized in that: The steam conservation constraint is expressed as: In the formula, G i,t is the steam extraction capacity of the steam extraction structure i of the carbon capture thermal power system at time t, G i ' ,t is the desorption steam consumption of the carbon capture system in the carbon capture thermal power system i at time t, is the steam supply of electric boiler j operating in conjunction with carbon capture thermal power system i at time t, is the equivalent steam supply of the heat storage device q operating in conjunction with the carbon capture thermal power system i at time t, N hs is the number of thermal storage devices operating in conjunction with the carbon capture thermal power system i.

4. The power system optimization dispatching method according to claim 1, characterized in that: The electrothermal coupling constraint is expressed as: In the formula, is the total power generation of carbon capture thermal power system i at time t, are the available electric power of the carbon capture thermal power system i at the vertex k1 of the area ABC1D and the amount of steam obtained by the carbon capture system, are the available electric power of the carbon capture thermal power system i at the end point k2 of line segment C2D2 and the amount of steam obtained by the carbon capture system, and are the coefficients to be decided, and Satisfy the constraints: In the formula, S LPzero are binary variables. If the electric and thermal operation point of the carbon capture thermal power system i falls within the region ABC1D at time t, then Take 1, Take 0, if the electric heating operation point of the carbon capture thermal power system i falls on the line segment C2D2 at time t, then Take 1, Take 0, if the carbon capture thermal power system i is shut down, then Take 0, otherwise take 1, S LPzero is a variable representing whether the carbon capture thermal power system i adopts the low-pressure cylinder zero-output transformation. If the low-pressure cylinder zero-output transformation is adopted, S LPzero is 1, otherwise it is 0; Among them, area ABC1D is the feasible domain considering electrothermal coupling. In area ABC1D, boundary AB represents the variation range of available electric power of thermal power generation system under pure condensing condition, boundary BC1 represents the desorption heating condition when the boiler maintains the minimum evaporation amount in the thermal power generation system, boundary C1D represents the desorption heating condition when the minimum condensation amount of the low-pressure cylinder is reached, and boundary DA represents the desorption heating condition when the boiler maintains the maximum continuous evaporation amount. The above boundaries together enclose the convex polygonal feasible domain of carbon capture thermal power; line segment C2D2 is the increased area of ​​the feasible domain after adding the zero-output transformation of the low-pressure cylinder, and area ABC1D∪C2D2 is the feasible domain considering electrothermal coupling when the carbon capture thermal power system i adopts the zero-output transformation of the low-pressure cylinder but does not introduce auxiliary equipment and parallel extraction structure.

5. The power system optimization dispatching method according to claim 1, characterized in that: The constraints also include ramp constraints of thermal power generation systems, minimum startup time constraints, minimum shutdown time constraints, power system power balance constraints, electric boiler operation constraints, heat storage device operation constraints, carbon capture system operation constraints, and renewable energy grid-connected power constraints.

6. The method for optimizing and dispatching a power system according to claim 1, characterized in that: The objective function is expressed as: In the formula, f is the total cost, The fuel costs of conventional thermal power and thermal power generation systems operating in conjunction with carbon capture systems are: They are the start-up and shutdown costs of conventional thermal power and thermal power generation systems operating in conjunction with carbon capture systems; The cost of transporting and storing captured carbon dioxide; C C For carbon trading costs; Penalty costs for wind curtailment; Penalty cost for abandoning light.

7. The power system optimization dispatching method according to claim 1, characterized in that: Equivalent power consumption of the throttling action of the pressure reducing valve in the parallel extraction structure at time t satisfy: In the formula, S throttle is a variable representing whether the steam extraction structure adopts a parallel steam extraction structure formed by a back pressure steam turbine and a pressure reducing valve. If a parallel steam extraction structure is adopted, S throttle is 1, if only the steam turbine is used, it is 0, G i,t is the steam extraction capacity of the steam extraction structure of the carbon capture thermal power system i at time t, η LDST It is the power generation of the back pressure steam turbine per unit steam volume.

8. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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