Optimal dispatching method and system of power system with biomass blending combustion coal-fired unit

Abstract

The application discloses a kind of biomass blending combustion coal-fired unit containing power system optimization scheduling method and system, belong to electrical engineering technical field.The application is configured with storage device in biomass blending combustion coal-fired unit, and with the sum of power generation cost, coal-fired unit start-up cost, carbon trading cost and penalty of abandoned electricity minimum as objective function, under the constraint condition satisfying including mass conservation constraint and inventory dynamic balance constraint, the input and output flow of storage device, biomass pyrolysis, coal input, carbon emission and renewable energy time level scheduling plan are optimized;In the above process, by controlling the storage amount and input and output flow of various pyrolysis products, the biomass pyrolysis process and coal-fired unit power generation process are decoupled, so that the hard constraint that pyrolysis product yield and consumption must be strictly matched in real time is relaxed, the coal-fired unit operation domain is expanded, the operation flexibility of coal-fired unit is improved, and large-scale renewable energy can be absorbed.

Description

Technical Field

[0001] This invention belongs to the field of electrical engineering technology, and more specifically, relates to an optimized scheduling method and system for a power system containing biomass co-fired coal-fired units. Background Technology

[0002] In recent years, the installed capacity of renewable energy sources, represented by wind power and photovoltaic power, has grown rapidly. However, to ensure the safe operation of the power system, a large number of coal-fired power units still need to be in operation, resulting in insufficient power system regulation capacity and difficulty in absorbing large-scale intermittent renewable energy. On the other hand, biomass co-firing retrofitting of coal-fired power units is an important technical path for the low-carbon transformation of the power system, but its operational flexibility has not been effectively explored, and its potential to support the absorption of renewable energy is difficult to release. Therefore, it is of great significance to study an optimized dispatching method for power systems that include biomass co-firing coal-fired power units.

[0003] In existing optimization dispatch methods for power systems that include coal-fired power units with biomass co-firing, the operating model for coal-fired power units coupled with biomass co-firing only considers the substitution of coal by biomass fuel to reduce carbon emissions from coal-fired power units. However, under this approach, the biomass pyrolysis process is coupled with the power generation process of coal-fired power units, resulting in a small operating domain and low operational flexibility of coal-fired power units. This leads to problems such as a small dispatchable domain for the power system, weak power system regulation capacity, and insufficient interactive operation capability between coal-fired power units and renewable energy, making it difficult to support the large-scale consumption of renewable energy. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides an optimized scheduling method and system for power systems with biomass co-firing coal-fired units, in order to solve the technical problems of small operating range and low operating flexibility of coal-fired units in the existing technology.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an optimized scheduling method for a power system comprising a biomass-co-fired power unit; wherein the power unit comprises: a pyrolysis device, a storage device, and a boiler; the pyrolysis device is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage device is used to store the pyrolysis products input from the pyrolysis device and control the output of these products to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis device and the storage device, as well as pulverized coal input from an external pulverizing system, to realize the co-combustion of biomass and coal for power generation;

[0006] The above-mentioned optimized scheduling methods include:

[0007] Obtain the power system dispatch model; the objective function of the dispatch model is to minimize the sum of generation cost, coal-fired unit start-up cost, carbon trading cost and curtailment penalty. The optimization variables include the start-up status of each coal-fired unit in the system at each time point, the net carbon dioxide emissions of each coal-fired unit, the amount of renewable energy curtailed by each renewable energy unit, the input and output of each pyrolysis product and the amount of biochar stored in the storage device of each coal-fired unit, the input of pulverized coal in the boiler, and the input of biomass fuel in the pyrolysis device.

[0008] Solve the above scheduling model under constraints to obtain the optimal scheduling decision;

[0009] The constraints include: mass conservation constraints and inventory dynamic balance constraints; the mass conservation constraints include: for each pyrolysis product in any coal-fired unit, at each time point, the sum of its generation in the corresponding pyrolysis unit and its net output in the corresponding storage unit is equal to its consumption in the corresponding boiler; the inventory dynamic balance constraints include: for each pyrolysis product in any storage unit, its storage quantity at each time point is equal to the difference between its storage quantity at the previous time point and its net output at this time point.

[0010] More preferably, the above objective function is:

[0011]

[0012] in, Indicates the scheduling period; Indicates the number of coal-fired power units in the power system; Represents the first in the power system Unit mass coal cost of a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The unit mass biomass fuel cost of a coal-fired power unit; For the first Enter the number at the current time Biomass fuel quality of the pyrolysis unit of each coal-fired power unit; For the first The cost of starting up a single coal-fired power unit; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; This represents the transaction cost per unit mass of carbon emissions; For the first The coal-fired power unit was in the first Net carbon dioxide emissions at a given time; This indicates the number of renewable energy units in the power system; Indicates the first in the power system Unit renewable energy curtailment penalty for each renewable energy unit; Indicates the first The renewable energy unit was in the first The amount of renewable energy power curtailed at the current time.

[0013] More preferably, the above-mentioned mass conservation constraints include:

[0014]

[0015]

[0016]

[0017] The aforementioned inventory dynamic balance constraints include:

[0018]

[0019]

[0020]

[0021] in, , , The first The first moment in the power system at this time The output of syngas, pyrolysis oil, and biochar in the pyrolysis unit of a coal-fired power plant; and They were respectively in the second At this moment The output and input of syngas in the storage device of each coal-fired unit; , , The first At this moment The consumption of syngas, pyrolysis oil, and biochar in the boilers of each coal-fired unit; and The first At this moment The output and input of pyrolysis oil in the storage device of each coal-fired unit; and The first At this moment The output and input of biochar in the storage device of each coal-fired unit; For the first At this moment The amount of biochar stored in the storage device of each coal-fired unit; , , They are respectively At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; and These are the self-loss rates of syngas and pyrolysis oil, respectively. ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0022] More preferably, the first The coal-fired power unit was in the first Net carbon dioxide emissions at the current time The calculation formula is:

[0023]

[0024] in, Indicates the first Carbon emission factors of pulverized coal in a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The coal-fired power unit was in the first The amount of carbon dioxide emissions reduced by storing biochar at present; ; Indicates the first The amount of carbon dioxide emissions reduced per unit mass of biochar stored in a coal-fired power unit; Indicates the first At this moment The mass of biochar produced by biomass fuel pyrolysis in each coal-fired unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0025] More preferably, the above constraints also include: upper and lower limits for inventory levels, specifically including:

[0026]

[0027]

[0028]

[0029] in, , , The first At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; , , The first The capacity of the syngas, pyrolysis oil, and biochar storage devices in the storage units of each coal-fired power unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0030] More preferably, the above constraints also include: operational constraints of the pyrolysis unit in the coal-fired power unit; the... The operational constraints of the pyrolysis unit of a coal-fired power plant include:

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039] Among them, superscript Indicates the types of pyrolysis products; The time indicates syngas; The time indicates pyrolysis oil; The time indicates biochar; For the first The first moment in the power system at this time Pyrolysis products in the pyrolysis unit of a coal-fired power unit The output; Indicates the first The pyrolysis products generated per unit mass of biomass fuel in the pyrolysis unit of a coal-fired power unit The yield; Indicates the first At this moment The rate at which the pyrolysis unit of a coal-fired power plant processes biomass fuel; Indicates the first At this moment Energy consumption of the pyrolysis unit of a coal-fired power plant; Indicates the first Energy required for pyrolysis of a unit mass of biomass fuel in the pyrolysis unit of a coal-fired power plant; For the first The pyrolysis unit of the coal-fired power plant is in the first Indicator variables for startup at the current time. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Start at any time Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Do not start at any time; For the first Start-up energy consumption of the pyrolysis unit of a coal-fired power plant; It is an instruction for the first The pyrolysis unit of the coal-fired power plant is in the first The binary variable representing the running state at a given moment. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Always online; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Offline at all times; and They represent the first The upper and lower limits of the rate at which the pyrolysis unit of a coal-fired power plant processes biomass fuel; For the first Indicator variables for biomass indirect co-firing retrofit of coal-fired power units Indicates the first Several coal-fired power units have undergone biomass co-firing retrofitting. Indicates the first The coal-fired power units have not undergone biomass co-firing retrofitting; It is the first The pyrolysis unit of the coal-fired power plant is in the first The indicator variable for when the machine stops. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine is always shut down; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine never stopped running; and The first The pyrolysis unit of the coal-fired power plant is in the first The shortest time span between being in running and stopped states at any given moment; Indicates the scheduling period; It is the first during the scheduling period The maximum number of times a coal-fired power unit's pyrolysis unit can be started; For the first The pyrolysis unit of the coal-fired power plant is in the first It is constantly supplied to the corresponding boiler to replace the energy of the pyrolysis products of pulverized coal; , and The lower heating values ​​are syngas, pyrolysis oil, and biochar, respectively. , , The first At this moment The consumption of syngas, pyrolysis oil, and biochar in the boilers of each coal-fired unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0040] More preferably, the above constraints also include: operational constraints of the boiler in the coal-fired unit; The operating constraints of the boilers in each coal-fired unit include:

[0041]

[0042]

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051] in, In the first At any time without burning biomass Boiler efficiency of a coal-fired unit; For the first The lower heating value of pulverized coal in the boiler of a coal-fired unit; In the first Enter the number at the current time The quality of power coal for the boilers of each coal-fired unit; For the first The pyrolysis unit of the coal-fired power plant is in the first It is constantly supplied to the corresponding boiler to replace the energy of the pyrolysis products of pulverized coal; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; and They represent the first Minimum and maximum input power of the boilers of each coal-fired unit; and The first Minimum continuous online operation and downtime of each coal-fired power unit; To indicate the first The first coal-fired unit The binary variable that is currently halted. Indicates the first The first coal-fired unit Stop the machine at any time; Indicates the first The first coal-fired unit The machine is not shut down at the moment; Indicates the first The coal-fired power unit was in the first The startup status at any given moment; Indicates the first The coal-fired power unit was in the first Start at any time; Indicates the first The coal-fired power unit was in the first Not started at the moment; and The first The rate of upward and downward ramping of the boilers in a coal-fired unit; and The first Operating capacity of boilers for each coal-fired unit during startup and shutdown; For the first The boiler of the coal-fired unit was in the... Biomass co-firing rate at the current time; For the first The upper limit of the indirect co-firing rate of biomass in the boilers of a coal-fired unit; For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For the first At this moment Boiler efficiency when coal-fired units are indirectly coupled and co-fired; Indicates the first At this moment Energy consumption of the pyrolysis unit of a coal-fired power plant; and The first The maximum and minimum input thermal power of the steam turbine in a coal-fired unit; For the first At this moment Boiler efficiency of a coal-fired unit; Indicates the first Boiler efficiency of a coal-fired unit without co-firing biomass. It is the slope of the boiler efficiency as a function of the co-firing rate; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0052] More preferably, the above constraints also include: turbine operation constraints in coal-fired power units; wherein, the first The operating constraints of the steam turbines in a coal-fired power unit include:

[0053]

[0054]

[0055]

[0056]

[0057] in, For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For use in the first The number of nodes in the segmentation of the output curve of each coal-fired unit. The output curves of the coal-fired units were... Each node is divided into The first node corresponds to the minimum input thermal power of the steam turbine, and the last node corresponds to the maximum input thermal power of the steam turbine. As a continuous auxiliary variable, it represents the first... The coal-fired power unit was in the first The moment The weight of each node in the turbine power and generator power. It is a non-negative number; For the first The first coal-fired unit Thermal power at each node; For the first The coal-fired power unit was in the first The electrical power output at a given moment; For the first The first coal-fired unit Electrical power at each node; A binary auxiliary variable used to indicate the first... At this moment Is the turbine operating status of the coal-fired power unit at the [number]th [location]? Section; when Time indicates the first At this moment The turbine operating status of the coal-fired power unit is in the [missing information]. Section; when Time indicates the first At this moment The turbine operating status of the coal-fired power unit is not in the [number]th [position]. part; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0058] More preferably, the above constraints also include: system reserve constraints, power balance constraints, renewable energy unit output constraints, and line power flow constraints.

[0059] In a second aspect, the present invention provides a power system, comprising: a biomass co-fired coal-fired unit, a renewable energy unit, a transmission line, and a controller;

[0060] The biomass-co-fired power unit includes: a pyrolysis unit, a storage unit, and a boiler; the pyrolysis unit is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage unit is used to store the pyrolysis products input from the pyrolysis unit and control the output to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis unit and the storage unit, as well as the pulverized coal input from the external pulverizing system, to realize the co-combustion of biomass and coal for power generation;

[0061] The controller is used to execute the optimized scheduling method provided in the first aspect of the present invention.

[0062] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0063] 1. This invention provides an optimized scheduling method for a power system incorporating biomass-coated coal-fired power units, wherein storage devices are configured within the biomass-coated coal-fired power units. Based on this, with the objective function of minimizing the sum of power generation cost, coal-fired power unit start-up cost, carbon trading cost, and curtailment penalty, and under constraints including mass conservation constraints and dynamic inventory balance constraints, the method optimizes the input and output flow rates of the storage device, biomass pyrolysis, coal input, carbon emissions, and the time-level scheduling plan of renewable energy. In the above process, by controlling the storage amount and input and output flow rates of various pyrolysis products, the biomass... Decoupling the pyrolysis process from the power generation process of coal-fired units relaxes the hard constraint that the output and consumption of pyrolysis products must be strictly matched in real time. This allows coal-fired units to increase pyrolysis load and store excess products and reduce output during periods of high renewable energy generation, and release stored pyrolysis products and increase output during periods of insufficient renewable energy. This expands the operating range of coal-fired units, improves their operational flexibility, and consequently results in a larger dispatchable domain for the power system, higher power system regulation capacity, and stronger interactive operation capability between coal-fired units and renewable energy, which can support the large-scale consumption of renewable energy.

[0064] 2. Furthermore, the optimized scheduling method for a power system including biomass-co-fired coal-fired units provided by this invention calculates the net carbon dioxide emissions of each coal-fired unit at each time point. At the same time, the impact of thermal coal combustion and biochar storage on carbon dioxide emissions is fully considered. By flexibly arranging the power generation and storage of pyrolysis product biochar, the heat power input to the boiler can be flexibly adjusted, and the operating range of coal-fired units can be expanded.

[0065] 3. Furthermore, in the optimized scheduling method for a power system including a biomass-co-fired coal-fired unit provided by this invention, the constraints also include the operational constraints of the pyrolysis device in the coal-fired unit; and the operational constraints of the pyrolysis device established by this invention reflect the operational model of the pyrolysis device and the energy coupling relationship between the pyrolysis device and the boiler. By flexibly arranging the power generation and storage of the pyrolysis product biochar, the thermal power input to the boiler can be flexibly adjusted, further expanding the operating range of the coal-fired unit; at the same time, by storing biochar, the carbon emissions of the unit can be additionally offset, achieving lower carbon emissions.

[0066] 4. Furthermore, in the optimized scheduling method for power systems including biomass-co-fired coal-fired units provided by the present invention, the constraints also include the operating constraints of the boiler in the coal-fired unit; and the boiler operating constraints established by the present invention reflect the boiler operating model and the influence of biomass co-firing rate on the substitution effect of biomass pyrolysis products on power coal, which can further improve the flexibility of power coal substitution and further reduce the emissions from power generation of coal-fired units by adjusting the biomass co-firing rate of the coal-fired unit. Attached Figure Description

[0067] Figure 1 This is a structural diagram of a coal-fired power unit with a coupled pyrolysis product storage device, provided as an embodiment of the present invention.

[0068] Figure 2 This is a schematic diagram of the feasible region for scheduling biomass co-firing in a coal-fired power unit using a coupled pyrolysis product storage device provided in an embodiment of the present invention.

[0069] Figure 3 This is a comparison diagram of the biomass co-firing operation status of coal-fired power units in scenarios one and two, provided for embodiments of the present invention.

[0070] Figure 4 This is a comparison chart of the amount of renewable energy wasted in different time periods in Scenario 1 and Scenario 2 provided in the embodiments of the present invention.

[0071] Figure 5 This is a schematic diagram illustrating the dynamic inventory status of biomass pyrolysis products in Scenario 2 provided by an embodiment of the present invention. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0073] In this invention, the terms "first," "second," etc. (if present) in the invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0074] To achieve the above objectives, in a first aspect, the present invention provides an optimized scheduling method for a power system comprising a biomass-co-fired power unit; wherein the power unit comprises: a pyrolysis device, a storage device, and a boiler; the pyrolysis device is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage device is used to store the pyrolysis products input from the pyrolysis device and control the output of these products to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis device and the storage device, as well as pulverized coal input from an external pulverizing system, to realize the co-combustion of biomass and coal for power generation;

[0075] The above-mentioned optimized scheduling methods include:

[0076] Obtain the power system dispatch model; the objective function of the dispatch model is to minimize the sum of generation cost, coal-fired unit start-up cost, carbon trading cost, and curtailment penalty. The optimization variables include the start-up status of each coal-fired unit in the system at each time point, the net carbon dioxide emissions of each coal-fired unit, the amount of renewable energy curtailed by each renewable energy unit, the input and output of each pyrolysis product and the amount of biochar stored in the storage device of each coal-fired unit, the input of pulverized coal in the boiler, and the input of biomass fuel in the pyrolysis device; wherein, the generation cost includes the cost of thermal coal and the cost of biomass.

[0077] Solve the above scheduling model under constraints to obtain the optimal scheduling decision;

[0078] The constraints include: mass conservation constraints and inventory dynamic balance constraints; the mass conservation constraints include: for each pyrolysis product in any coal-fired unit, at each time point, the sum of its generation in the corresponding pyrolysis unit and its net output in the corresponding storage unit is equal to its consumption in the corresponding boiler; the inventory dynamic balance constraints include: for each pyrolysis product in any storage unit, its storage quantity at each time point is equal to the difference between its storage quantity at the previous time point and its net output at this time point.

[0079] It should be noted that the net output is the output minus the input.

[0080] In one alternative implementation, the objective function described above is:

[0081]

[0082] in, Indicates the scheduling period (in one alternative implementation, the scheduling period is one day, i.e., 24 hours); Indicates the number of coal-fired power units in the power system; Represents the first in the power system Unit mass coal cost of a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The unit mass biomass fuel cost of a coal-fired power unit; For the first Enter the number at the current time Biomass fuel quality of the pyrolysis unit of each coal-fired power unit; For the first The cost of starting up a single coal-fired power unit; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; This represents the transaction cost per unit mass of carbon emissions; For the first The coal-fired power unit was in the first Net carbon dioxide emissions at a given time; This indicates the number of renewable energy units in the power system; Indicates the first in the power system Unit renewable energy curtailment penalty for each renewable energy unit; Indicates the first The renewable energy unit was in the first The amount of renewable energy power curtailed at the current time.

[0083] In one alternative implementation, the above-mentioned mass conservation constraints include:

[0084]

[0085]

[0086]

[0087] in, , , The first The first moment in the power system at this time The output of syngas, pyrolysis oil, and biochar in the pyrolysis unit of a coal-fired power plant; and They were respectively in the second At this moment The output and input of syngas in the storage device of each coal-fired unit; , , The first At this moment The consumption of syngas, pyrolysis oil, and biochar in the boilers of each coal-fired unit; and The first At this moment The output and input of pyrolysis oil in the storage device of each coal-fired unit; and The first At this moment The output and input of biochar in the storage device of each coal-fired unit; For the first At this moment The amount of biochar stored in the storage device of each coal-fired unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0088] In one alternative implementation, the aforementioned dynamic inventory balance constraint includes:

[0089]

[0090]

[0091]

[0092] in, , , They are respectively At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; and These are the self-loss rates of syngas and pyrolysis oil, respectively. and They are respectively in At this moment The output and input of syngas in the storage device of each coal-fired unit; and They are respectively At this moment The output and input of pyrolysis oil in the storage device of each coal-fired unit; and They are respectively At this moment The output and input of biochar in the storage device of each coal-fired unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0093] In one optional implementation, the above constraints further include: upper and lower limits for inventory levels, specifically including:

[0094]

[0095]

[0096]

[0097] in, , , The first At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; , , The first The capacity of the syngas, pyrolysis oil, and biochar storage devices in the storage units of each coal-fired power unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0098] In one alternative implementation, the first The coal-fired power unit was in the first Net carbon dioxide emissions at the current time The calculation formula is:

[0099]

[0100] in, Indicates the first Carbon emission factors of pulverized coal in a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The coal-fired power unit was in the first The amount of carbon dioxide emissions reduced by storing biochar at present; ; Indicates the first The amount of carbon dioxide emissions reduced per unit mass of biochar stored in a coal-fired power unit; Indicates the first At this moment The mass of biochar produced by biomass fuel pyrolysis in each coal-fired unit; ; Indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

[0101] In one alternative implementation, the above constraints further include: operational constraints of the pyrolysis unit in the coal-fired power unit: wherein, the first The operating constraints of the boilers in each coal-fired unit include:

[0102] The relationship between the production of syngas, pyrolysis oil, and biochar and the input of biomass fuel satisfies:

[0103]

[0104] Among them, superscript Indicates the types of products from biomass pyrolysis. The time indicates synthesis gas. The time indicates pyrolysis oil. The time indicates biochar; Indicates the first The pyrolysis products generated per unit mass of biomass fuel in the pyrolysis unit of a coal-fired power unit The yield;

[0105] Energy consumption of pyrolysis unit satisfy:

[0106]

[0107] in, For the first The pyrolysis unit of the coal-fired power plant is in the first Indicator variables for startup at the current time. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Start at any time Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Do not start at any time; Indicates the first Energy required for pyrolysis of a unit mass of biomass fuel in the pyrolysis unit of a coal-fired power plant; For the first Start-up energy consumption of the pyrolysis unit of a coal-fired power plant;

[0108] The biomass mass input to the pyrolysis unit during operation satisfy:

[0109]

[0110] in, It is an instruction for the first The pyrolysis unit of the coal-fired power plant is in the first The binary variable representing the running state at a given moment. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Always online; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Offline at all times; and They represent the first The upper and lower limits of the rate at which the pyrolysis unit of a coal-fired power plant processes biomass fuel.

[0111] The operating status of the pyrolysis unit meets the following requirements:

[0112]

[0113] in, For the first Indicator variables for biomass indirect co-firing retrofit of coal-fired power units Indicates the first Several coal-fired power units have undergone biomass co-firing retrofitting. Indicates the first The coal-fired power units have not undergone biomass co-firing retrofitting.

[0114] The minimum start-up and shutdown times for the pyrolysis unit must meet the following requirements:

[0115]

[0116] in, It is the first The pyrolysis unit of the coal-fired power plant is in the first The indicator variable for when the machine stops. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine is always shut down; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine never stopped running; and The first The pyrolysis unit of the coal-fired power plant is in the first The shortest time span between being in running and stopped states at any given moment.

[0117] The relationship between the operating states of the pyrolysis unit satisfies:

[0118]

[0119] The pyrolysis unit's start-up and shutdown frequency must meet the following requirements:

[0120]

[0121] Indicates the scheduling period; It is the first during the scheduling period The maximum number of times a coal-fired power unit's pyrolysis unit can be started.

[0122] The pyrolysis unit supplies energy to the boiler as a substitute for the pyrolysis products of pulverized coal. satisfy:

[0123]

[0124] , and The values ​​are the lower heating values ​​of syngas, pyrolysis oil, and biochar, respectively.

[0125] In one optional implementation, the above constraints further include: operational constraints of the boiler in the coal-fired unit; wherein, the first The operating constraints of the boilers in each coal-fired unit include:

[0126] Boiler input total heat energy satisfy:

[0127]

[0128]

[0129] in, In the first At any time without burning biomass Boiler efficiency of a coal-fired unit; For the first The lower heating value of pulverized coal in the boiler of a coal-fired unit; In the first Enter the number at the current time The quality of power coal for the boilers of each coal-fired unit; For the first The pyrolysis unit of the coal-fired power plant is in the first It is constantly supplied to the corresponding boiler to replace the energy of the pyrolysis products of pulverized coal; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; and They represent the first The minimum and maximum input power of the boilers of each coal-fired unit.

[0130] The boiler's minimum online operating time and minimum downtime meet the following requirements:

[0131]

[0132] in, and The first Minimum continuous online operation and downtime of each coal-fired power unit; To indicate the first The first coal-fired unit The binary variable that is currently halted. Indicates the first The first coal-fired unit Stop the machine at any time; Indicates the first The first coal-fired unit The machine is not shut down at the moment; Indicates the first The coal-fired power unit was in the first The startup status at any given moment; Indicates the first The coal-fired power unit was in the first Start at any time; Indicates the first The coal-fired power unit was in the first It is not currently running.

[0133] The boiler's ramp-up rate satisfies:

[0134]

[0135] in, and The first The rate of upward and downward ramping of the boilers in a coal-fired unit; and The first Operating capacity of the boilers of each coal-fired unit during startup and shutdown.

[0136] The operating state transition relationship of coal-fired power units satisfies:

[0137]

[0138] Biomass co-firing rate in boilers satisfy:

[0139]

[0140]

[0141] in, For the first The upper limit of the biomass indirect co-firing rate in the boilers of a coal-fired unit.

[0142] The heat power input from the boiler to the steam turbine satisfies:

[0143]

[0144]

[0145] in, For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For the first At this moment Boiler efficiency when coal-fired units are indirectly coupled and co-fired; Indicates the first At this moment Energy consumption of the pyrolysis unit of a coal-fired power plant; and The first The maximum and minimum input thermal power of the steam turbine in a coal-fired unit.

[0146] Boiler efficiency satisfy:

[0147]

[0148] in, Indicates the first Boiler efficiency of a coal-fired unit without co-firing biomass. It is the slope of the boiler efficiency as a function of the co-firing rate.

[0149] In one optional implementation, the above constraints further include: turbine operation constraints in a coal-fired unit; wherein, the first The operating constraints of the steam turbines in a coal-fired power unit include:

[0150] The steam turbine-generator unit output power meets the following requirements:

[0151]

[0152]

[0153]

[0154]

[0155] in, For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For use in the first The number of nodes in the segmentation of the output curve of each coal-fired unit. The output curves of the coal-fired units were... Each node is divided into The first node corresponds to the minimum input thermal power of the steam turbine, and the last node corresponds to the maximum input thermal power of the steam turbine. As a continuous auxiliary variable, it represents the first... The coal-fired power unit was in the first The moment The weight of each node in the turbine power and generator power. It is a non-negative number; For the first The first coal-fired unit Thermal power at each node; For the first The coal-fired power unit was in the first The electrical power output at a given moment; For the first The first coal-fired unit Electrical power at each node; A binary auxiliary variable used to indicate the first... At this moment Is the turbine operating status of the coal-fired power unit at the [number]th [location]? Section; when Time indicates the first At this moment The turbine operating status of the coal-fired power unit is in the [missing information]. Section; when Time indicates the first At this moment The turbine operating status of the coal-fired power unit is not in the [number]th [position]. part.

[0156] Preferably, in an optional implementation, the above constraints further include: system reserve constraints, power balance constraints, renewable energy unit output constraints, and line power flow constraints.

[0157] In one optional implementation, the above-mentioned system backup constraints specifically include:

[0158]

[0159] in, Indicates the number of coal-fired power units in the power system; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; Indicates the first The maximum electrical power of each coal-fired unit; This indicates the number of renewable energy units in the power system; Indicates the first The renewable energy unit was in the first Capacity factor at time t; Indicates the first Rated capacity of each renewable energy unit; Indicates the number of load nodes; Indicates the first The load node at the ... Load at any given moment; and These are the upper and lower reserve coefficients of the power system, respectively. Indicates the first Minimum electrical power of each coal-fired unit; ; Indicates the scheduling period.

[0160] In one optional implementation, the aforementioned power balance constraints specifically include:

[0161]

[0162] in, Indicates the number of coal-fired power units in the power system; For the first The coal-fired power unit was in the first The electrical power output at a given moment; This indicates the number of renewable energy units in the power system; For the first The renewable energy unit was in the first Current power output; This refers to the number of external power transmission lines. For the region where the power system is located and the first The first external power transmission line The switching power at that moment; Indicates the number of load nodes; Indicates the first The load node at the ... Load at any given moment; ; Indicates the scheduling period.

[0163] In one optional implementation, the above-mentioned renewable energy unit output constraints specifically include:

[0164]

[0165] in, For the first The renewable energy unit was in the first Current power output; Indicates the first The renewable energy unit was in the first Capacity factor at time t; Indicates the first Rated capacity of each renewable energy unit; ; This indicates the number of renewable energy units in the power system; ; Indicates the scheduling period.

[0166] In one optional implementation, the aforementioned line power flow constraints specifically include:

[0167]

[0168] in, Indicates the first The power transmission limit of an external transmission line; Indicates the first The coal-fired power unit and the first The power flow distribution transfer factor of an external transmission line; For the first The coal-fired power unit was in the first The electrical power output at a given moment; This indicates the number of renewable energy units in the power system; Indicates the first The renewable energy unit and the first The power flow distribution transfer factor of an external transmission line; For the first The renewable energy unit was in the first Current power output; This refers to the number of external power transmission lines. Indicates the first The node where the external transmission line is located is related to the first The power flow distribution transfer factor of an external transmission line; For the region where the power system is located and the first The first external power transmission line The switching power at that moment; Indicates the number of load nodes; Indicates the first The load node and the first The power flow distribution transfer factor of an external transmission line; Indicates the first The load node at the ... Load at any given moment; ; ; Indicates the scheduling period.

[0169] To further illustrate the optimized scheduling method for a power system including a biomass-co-fired coal-fired unit provided by the present invention, a specific embodiment is described in detail below:

[0170] The biomass-co-fired power unit provided in this implementation is a new type of unit formed by modifying a traditional coal-fired power unit. Its basic components are as follows: Figure 1 As shown, it includes a pyrolysis unit, a storage unit, a boiler, and a steam turbine (i.e., a steam turbine-power generation unit), whose functions are respectively: pyrolyzing biomass to produce multiple products and purifying and separating them; storing and controlling the flow of pyrolysis products; co-firing pulverized coal with biomass pyrolysis products; and generating electricity using high-temperature and high-pressure steam.

[0171] In existing optimization scheduling methods for power systems that include coal-fired power plants with biomass co-firing, the operating model for these plants only considers the substitution of coal with biomass fuel. While this can reduce carbon emissions from coal-fired units, it fails to improve their operational flexibility, resulting in weak power system regulation capabilities and insufficient interaction between coal-fired units and renewable energy sources. This makes it difficult to support the large-scale absorption of renewable energy. To address this issue, this embodiment provides an optimization scheduling method for power systems that include coal-fired power plants with biomass co-firing. The overall concept is as follows: during periods of high renewable energy generation and a negative net load on the power system, the pyrolysis unit operates at a high load. At this time, the energy consumption of biomass pyrolysis increases, the power plant's output power decreases, and the absorption of renewable energy is improved. The amount of biomass pyrolysis products generated exceeds the amount consumed, and the excess products are temporarily stored by a storage device. During periods of renewable energy shortage and a positive net load on the power system, the pyrolysis unit operates at low load or is shut down. In this state, the energy consumption of biomass pyrolysis decreases or drops to zero, increasing the power plant's output to meet the electricity load. The amount of biomass pyrolysis products generated is less than the amount consumed, and the products in the storage device are used for power generation. During periods of supply-demand equilibrium, all biomass pyrolysis products are used for power generation, and the amount of biomass pyrolysis products stored in the storage device remains constant.

[0172] Based on the above concepts, this embodiment first analyzes the energy consumption and material conversion of the pyrolysis device, and constructs a refined operating model of the pyrolysis device. Details are as follows:

[0173] For pyrolysis devices, the synthesis gas (i.e., pyrolysis gas) is... Figure 1 The combined gas production and pyrolysis oil production (i.e., Figure 1 The relationship between bio-oil and biochar production and biomass fuel input is expressed by equation (1):

[0174] (1)

[0175] In the formula, superscript This indicates the types of biomass pyrolysis products in the pyrolysis unit. The time indicates synthesis gas. The time indicates pyrolysis oil. The time indicates biochar; for Biomass pyrolysis products The output; The mass of biomass used for pyrolysis, The production of biomass pyrolysis per unit mass Yield of the product.

[0176] Since biomass pyrolysis is an endothermic reaction, and the heat source comes from the flue gas produced by fuel combustion in the boiler, the energy consumption of the pyrolysis device is calculated by equation (2):

[0177] (2)

[0178] In the formula, This is an indicator variable for starting the pyrolysis unit. Indicates the first The pyrolysis unit in the coal-fired power unit is in the first Start at any time; The energy required for the pyrolysis of a unit mass of biomass. This represents the energy consumption for starting up the pyrolysis unit.

[0179] The mass of biomass fuel processed by the pyrolysis unit during operation is limited by equation (3):

[0180] (3)

[0181] In the formula, It means the first In the coal-fired power unit, the pyrolysis unit is in the... The running status at any given moment, This indicates that the generator unit is online. This indicates that the generator set is offline; and These are the upper and lower limits of the rate at which the pyrolysis unit processes biomass feedstock.

[0182] The operational constraints of the pyrolysis unit only apply to biomass indirect coupling and co-firing units. Therefore, the operating state of the pyrolysis unit satisfies equation (4):

[0183] (4)

[0184] In the formula, As an indicator variable for indirect co-firing modification of biomass, This indicates that the unit has undergone biomass co-firing modification.

[0185] The minimum start-up and shutdown time limit for the pyrolysis unit is expressed by equation (5):

[0186] (5)

[0187] In the formula, It is an indicator variable for the shutdown of the pyrolysis unit. Indicates coal-fired power unit The intermediate pyrolysis unit in Always shut down and These represent the shortest time spans for the pyrolysis unit to be in operation and shutdown, respectively.

[0188] The relationship between the operating states of the pyrolysis unit is constrained by equation (6):

[0189] (6)

[0190] In order to reduce metal fatigue and thermal stress damage to equipment such as pyrolysis devices caused by start-up and shutdown, Equation (7) also limits the number of start-ups and shutdowns of the pyrolysis device during operation to avoid frequent start-ups and shutdowns during the scheduling cycle.

[0191] (7)

[0192] In the formula, Indicates the scheduling period; This is a limit on the number of times the pyrolysis unit can be started during the scheduling period.

[0193] The energy of the pyrolysis products transported from the pyrolysis unit to the boiler to replace pulverized coal is calculated using equation (8):

[0194] (8)

[0195] In the formula, , , Indicates the first The coal-fired power unit was in the first The quality of syngas, pyrolysis oil, and biochar used for power generation at all times. , and The values ​​are the lower heating values ​​of syngas, pyrolysis oil, and biochar, respectively.

[0196] The carbon dioxide emissions offset by biochar sequestration are calculated using equation (9):

[0197] (9)

[0198] In the formula, Indicates coal-fired power unit exist The quality of biochar sequestration at all times This indicates the amount of carbon dioxide emissions reduced by the amount of biochar stored per unit mass.

[0199] Secondly, the mass conservation and dynamic inventory balance of each product in the storage device were analyzed. The storage device in... The mass conservation of pyrolysis oil, syngas, and biochar during the time period is shown in equations (10) to (12). For pyrolysis oil and syngas, the sum of their generation and the net output of the storage device equals the boiler consumption; for biochar, since it can be directly sealed and carbon reduced, the sum of its generation and the net output of the storage device equals the sum of the boiler consumption and the sealed amount.

[0200] (10)

[0201] (11)

[0202] (12)

[0203] In the formula, and For the first The syngas output and input of the storage device at any given time; and For the first The output and input of pyrolysis oil in the storage device at any given time; and For the first The output and input of biochar from the product storage device at any given time.

[0204] The dynamic changes in the inventory of each product in the storage device are shown in equations (13) to (15):

[0205] (13)

[0206] (14)

[0207] (15)

[0208] In the formula, , , They are respectively Time period The inventory of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; and These are the self-loss rates of syngas and pyrolysis oil, respectively.

[0209] The upper and lower limits of inventory for each product are constrained as shown in equations (16) to (18):

[0210] (16)

[0211] (17)

[0212] (18)

[0213] In the formula, , , The first The capacity of the storage devices for syngas, pyrolysis oil, and biochar in each coal-fired unit.

[0214] Then, this embodiment considers the impact of co-firing of biomass pyrolysis products on boiler operating efficiency and carbon emissions, and performs a refined modeling of the boiler. Specifically:

[0215] The total thermal energy input to the boiler includes two parts: the thermal energy of pyrolysis products and the thermal energy of pulverized coal, as expressed by equation (19):

[0216] (19)

[0217] In the formula, and The first Time of the first The total thermal energy and pulverized coal input to the boiler in each coal-fired unit; It represents the lower heating value of pulverized coal.

[0218] The upper and lower limits of boiler input power are constrained by equation (20):

[0219] (20)

[0220] In the formula, A binary variable indicating the online status of a coal-fired power unit. Indicates the first The first coal-fired unit Always online and running. Indicates the first The first coal-fired unit Always offline. and The first The minimum and maximum input power of the boiler in each coal-fired unit.

[0221] Boiler operation is also constrained by minimum online operation and downtime, as shown in equation (21):

[0222] (twenty one)

[0223] In the formula, To indicate the first The coal-fired power unit was in the first Binary variables that are started at any time, Indicates the first The coal-fired power unit was in the first Start at any time; To indicate the first The coal-fired power unit was in the first Binary variables that are constantly halting. Indicates the first The coal-fired power unit was in the first The machine is always shut down; and The first The minimum continuous online operation and downtime of each coal-fired power unit.

[0224] The ramp-up rate of boiler operation is constrained by equation (22):

[0225] (twenty two)

[0226] In the formula, and The first The rate at which the boilers of a coal-fired unit climb uphill and downhill; and These refer to the boiler's operating capacity during startup and shutdown, respectively.

[0227] The state transition relationship of a coal-fired power unit must satisfy equation (23):

[0228] (twenty three)

[0229] Biomass co-firing rate in boilers Calculated by equation (24), that is, the ratio of the heat generated by the combustion of pyrolysis products to the total combustion input into the boiler; the upper limit of the co-firing rate is limited by equation (25):

[0230] (twenty four)

[0231] (25)

[0232] In the formula, This represents the upper limit of the biomass indirect coupling co-firing rate.

[0233] The heat power input from the boiler to the turbine-power generation unit is calculated by equation (26), which is the total usable heat energy generated by combustion minus the heat energy supplied for biomass pyrolysis:

[0234] (26)

[0235] In the formula, For the first Coal-fired power units Input the thermal power of the steam turbine; For the first The first coal-fired unit The efficiency of coal-fired boilers during indirect coupling of combustion.

[0236] Because the pyrolysis products and pulverized coal have significantly different constituent elements and calorific values, co-firing them causes the boiler operating efficiency to decrease approximately linearly with increasing co-firing rate. Therefore, the first... The coal-fired power unit was in the first Efficiency of coal-fired boilers when indirect coupling combustion Calculated using equation (27):

[0237] (27)

[0238] In the formula, It is the slope of boiler efficiency as a function of co-firing rate. Indicates the first Boiler efficiency of a coal-fired unit without co-firing biomass.

[0239] The upper and lower limits of the turbine input power, i.e. the heat power input from the boiler to the turbine-generator unit, are constrained as shown in equation (28):

[0240] (28)

[0241] In the formula, and The first The maximum and minimum input thermal power of the steam turbine of each coal-fired unit.

[0242] The net emissions of coal-fired units are calculated using equation (29), including carbon dioxide produced by pulverized coal combustion and carbon dioxide offset by biochar sequestration:

[0243] (29)

[0244] In the formula, For the first The coal-fired power unit was in the first Net carbon dioxide emissions at any given time; It is the carbon emission factor of pulverized coal.

[0245] Next, the steam turbine is modeled. The steam turbine-power generation unit uses high-temperature, high-pressure steam generated from heat input from the boiler to drive blades to rotate, thus generating electricity by the rotor cutting through a magnetic field. The nonlinear power generation efficiency curve is considered, such as... Figure 2 As shown, the output power is calculated and constrained by equations (30)-(33):

[0246] (30)

[0247] (31)

[0248] (32)

[0249] (33)

[0250] in, For the first The coal-fired power unit was in the first The electrical power output at any given time; For use in the first The number of nodes in the output curve of a coal-fired unit segmented, i.e., the first... The output curves of the coal-fired units were... Each node is divided into The first node corresponds to the minimum input thermal power of the steam turbine, and the last node corresponds to the maximum input thermal power of the steam turbine. As a continuous auxiliary variable, it represents the first... The coal-fired power unit was in the first Time of the first The weight of each node in the turbine power and generator power. It is a non-negative number; This is a binary auxiliary variable indicating whether the current turbine operating state is at the [number]th [position]. part.

[0251] Specifically, Figure 2 The union of line segment AB and quadrilateral CDEF is given. CD and E'F' represent the operating trajectories where all biochar is used for co-firing and power generation under the boiler's maximum and minimum operating power, respectively. C'D' and the boundary of EF represent the operating trajectories where all biochar is used for storage under the boiler's maximum and minimum operating power. After coupling the pyrolysis product storage system, the imbalance mass of generated and consumed pyrolysis products under any co-firing rate is replenished by the input or output inventory of the storage system. Therefore, biomass pyrolysis and power plant power generation processes are completely decoupled, and the operating domain is expanded to the quadrilateral region AGEH, where AG is the maximum input power of the turbine, determined by the rated power of the power plant; EH is the minimum input power of the turbine, which is the minimum operating power of the boiler minus the smaller value between the maximum operating load of the pyrolysis furnace and the minimum operating thermal power of the turbine.

[0252] For typical operating conditions, when a high co-firing rate and high output power are required, the energy used for biomass pyrolysis is reduced and the stored products are instead output to the boiler system for co-firing. In this case, the unit can operate in the DG section. When low power operation is required, the boiler operates at minimum power and the biomass pyrolysis unit operates at maximum load. In this case, the coal-fired unit generally operates in the EH section.

[0253] Finally, this embodiment combines the operation models of the pyrolysis unit, storage unit, boiler, and turbine to generate a power system dispatch model coupled with the storage unit. The power system dispatch model takes the minimum sum of power generation cost, coal-fired unit start-up cost, carbon trading cost, and curtailment penalty as its objective function. The optimization variables are the start-up status of each coal-fired unit in the system at each time point, the net carbon dioxide emissions of each coal-fired unit, the renewable energy curtailment of each renewable energy unit, the input and output of each pyrolysis product and the amount of biochar stored in the storage unit of each coal-fired unit, the input of pulverized coal in the boiler, and the input of biomass fuel in the pyrolysis unit.

[0254] Obtain the yields of various products from the pyrolysis unit of a biomass co-fired coal-fired power plant. Energy required for the pyrolysis of a unit mass of biomass Energy consumption for starting up the pyrolysis unit Lower limit of biomass quality processed by pyrolysis unit and upper limit Coal powder carbon emission factors Shortest online time span of pyrolysis unit and the shortest offline time span Maximum number of times the pyrolysis unit can be started Low heating value of syngas Low heating value of pyrolysis oil Low heating value of biochar Low calorific value of pulverized coal Boiler minimum input power and maximum input power Minimum continuous online operating time of the unit and downtime Uphill climbing rate and downhill climbing rate Boiler start-up capacity and shutdown operating capacity Upper limit of blending rate Boiler efficiency without biomass co-firing The slope of boiler efficiency change with co-firing rate Thermal power at the segment points of the turbine-generator efficiency curve and electrical power The reduction in carbon dioxide emissions per unit mass of biochar stored Obtain the power load of each load node in the power system at each time point. Capacity factor of each renewable energy unit at each time point , Upper reserve coefficient and lower reserve coefficient Power flow distribution transfer factor between coal-fired units and tie lines Power flow distribution transfer factor of renewable energy units and interconnection lines Power flow distribution transfer factor of external transmission lines and tie lines , load node and tie line power flow distribution transfer factor Substituting the above parameters into the power system dispatch model, and under the premise of satisfying the constraints of mass conservation, inventory dynamic balance, power balance, system reserve, line power flow, renewable energy output, and the operating constraints of pyrolysis devices, storage devices, boilers, and turbines in coal-fired units, the optimal solution is generated for the starting status of each coal-fired unit in the system at each moment during the dispatch cycle, the net carbon dioxide emissions of each coal-fired unit, the renewable energy curtailment of each renewable energy unit, the input and output of each pyrolysis product and the amount of biochar stored in the storage devices of each coal-fired unit, the input of pulverized coal in the boiler, and the input of biomass fuel in the pyrolysis device. This enables the coordinated operation of biomass-blended coal-fired units and renewable energy units, improves the absorption of renewable energy, and reduces carbon emissions from power system operation.

[0255] In summary, this embodiment proposes an optimized operation method for biomass co-firing in coal-fired power plants that considers the storage of pyrolysis products, thereby decoupling the biomass pyrolysis unit from the power generation process of the coal-fired unit. By configuring storage devices for storing pyrolysis products such as pyrolysis oil, syngas, and biochar, the product production process of the pyrolysis unit can be decoupled from the power plant's consumption process on a time scale, thus relaxing the hard constraint that the production and consumption of pyrolysis products must be strictly matched in real time. By controlling the quality of pyrolysis products input and output to the storage device, the imbalance between supply and demand of pyrolysis products in different time periods can be absorbed, thereby effectively expanding the scheduling feasibility domain of the power plant, with the following effect: Figure 2 As shown, when renewable energy is scarce, the storage device can output pyrolysis products to increase the power plant's output power, thereby reducing CO2 emissions from power generation. Conversely, when renewable energy is abundant, storing pyrolysis products reduces the power plant's output power, enhancing its renewable energy absorption capacity. This model provides a new technological path for the transformation of coal-fired power plants from traditional baseload power sources to supportive power sources with both low-carbon fuel substitution and flexible regulation functions. It helps promote the low-carbon transformation of coal-fired power plants, enhances the resource supply regulation capacity of the new power system, and provides important support for the power industry to coordinate energy security, flexibility improvement, and carbon emission reduction goals. Simultaneously, the real-time carbon emissions and output power of coal-fired units are included in the objective function and power balance, respectively, further effectively realizing the coordinated scheduling of coal-fired and renewable energy units.

[0256] The following analysis, based on simulation results, further verifies the beneficial effects achievable in this embodiment.

[0257] Based on the IEEE-6-bus power system, a case study analysis is conducted to compare the power system operating costs, carbon emissions, renewable energy consumption, and dynamics of biomass pyrolysis product production, consumption, and storage device inventory before and after equipping biomass co-firing power plants with pyrolysis product storage devices.

[0258] The IEEE-6-bus system comprises three conventional thermal power units ( , , Both have a rated capacity of 169MW; two coal-fired units capable of co-firing biomass ( , Both wind farms have a rated capacity of 247MW and can achieve a maximum biomass co-firing rate of 30%. and a photovoltaic power station In this implementation example, it is assumed that the carbon tax price is 200 yuan / ton, the curtailment penalty is 300 yuan / MWh, the biomass price is 450 yuan / ton, the coal price is 750 yuan / ton, and both biomass co-firing power plants are equipped with storage devices that can store 200 tons of bio-oil, 200 tons of syngas, and 200 tons of biochar.

[0259] To compare the operational optimization effects of co-firing biomass in coal-fired power units before and after configuring pyrolysis product storage devices, a controlled variable method was used to set up two simulation scenarios. In scenario one, the unit... and Biomass can be co-fired, but no pyrolysis product storage device is installed; in scenario two, the unit... and It employs biomass co-firing and is equipped with storage devices for biochar, pyrolysis oil, and syngas pyrolysis products. (Except for the unit...) and In addition, the load, wind and solar power output, and other constraints in the power system are the same in both scenario one and scenario two.

[0260] Based on simulation analysis, the main operating results of Scenario 1 and Scenario 2 are shown in Table 1, including details of operating costs, renewable energy consumption, and carbon dioxide emissions.

[0261] Table 1

[0262]

[0263] Compared to Scenario 1, Scenario 2, by equipping coal-fired power plants with pyrolysis product storage devices, reduces daily operating costs by 167,000 yuan. This includes a 103,000 yuan reduction in fuel costs; a 9,000 yuan reduction in carbon tax costs and a 53-ton reduction in carbon dioxide emissions; and a 53,000 yuan reduction in renewable energy curtailment penalties. This is primarily because the storage devices lower the minimum output power of coal-fired power plants during periods of high renewable energy generation, increasing the capacity for renewable energy absorption and reducing system curtailment by 81.7%.

[0264] Comparison of the operating states of coal-fired power plants with coupled biomass co-firing in Scenario 1 and Scenario 2, for example Figure 3 As shown. In a scenario where a biomass pyrolysis product storage device is configured, two coal-fired power plants capable of co-firing biomass are shown. and Both units reached their minimum output between 3:00 AM and 8:00 AM. Compared to units without storage devices, the minimum output power of the two units decreased by 21.5MW and 15.6MW respectively, representing reductions of 27.2% and 21.54%, effectively promoting the consumption of renewable energy. During the period from 3:00 PM to midnight when renewable energy resources were insufficient, the two units reached their maximum output power. Compared to units without storage devices, the maximum output power increased by 11.4MW and 18.5MW respectively, representing increases of 5.3% and 8.3%, effectively supporting power supply during periods of renewable energy scarcity.

[0265] Comparison of abandoned electricity between Scenario 1 and Scenario 2 during peak renewable energy generation periods (3 AM - 8 AM) Figure 4 As shown, after configuring the pyrolysis product storage device, the renewable energy at points 3, 7, and 8 was fully utilized, and the curtailment was completely eliminated; while the curtailment of renewable energy at points 4-6 decreased by 67.8%, 62.9%, and 79.6%, respectively.

[0266] After configuring the pyrolysis product storage device in Scenario 2, the product inventory of the storage device is as follows: Figure 5 As shown, during the peak renewable energy generation period from 2:00 AM to 8:00 AM, the inventory of biomass pyrolysis products stored in the product storage device increases, resulting in a net inflow of products. However, from 1:00 PM to midnight, the system's net load is negative, so pyrolysis products are output from the storage device to the boiler for power generation, and the inventory of biomass pyrolysis products gradually decreases. From 9:00 AM to 12:00 PM, the production of biomass pyrolysis products and the consumption by the boiler are basically balanced, and the product inventory in the storage device remains at a relatively high level.

[0267] Overall, through the above-mentioned technical solutions conceived in this invention, the minimum output level of biomass-co-fired power units is reduced and the maximum output capacity is increased. In static conditions, the dispatchable domain of coal-fired power units is expanded, and in dynamic conditions, the power allocation of biomass pyrolysis devices is more flexible on a time scale. This effectively improves the power system's ability to absorb renewable energy, reduces the carbon emissions of the power system, and reduces the total operating cost of the system, providing technical support for the coordinated transformation of coal-fired power plants towards low-carbonization and flexibility.

[0268] In a second aspect, the present invention provides a power system, comprising: a biomass co-fired coal-fired unit, a renewable energy unit, a transmission line, and a controller;

[0269] The biomass-co-fired power unit includes: a pyrolysis unit, a storage unit, and a boiler; the pyrolysis unit is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage unit is used to store the pyrolysis products input from the pyrolysis unit and control the output to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis unit and the storage unit, as well as the pulverized coal input from the external pulverizing system, to realize the co-combustion of biomass and coal for power generation;

[0270] The controller is used to execute the optimized scheduling method provided in the first aspect of the present invention.

[0271] The related technical solutions are the same as the optimized scheduling method provided in the first aspect of this invention, and will not be described in detail here.

[0272] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for optimal dispatch of an electricity system comprising a biomass co-firing coal-fired power plant, characterized in that, The coal-fired power unit includes: a pyrolysis unit, a storage unit, and a boiler; the pyrolysis unit is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage unit is used to store the pyrolysis products input from the pyrolysis unit and control the output of these products to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis unit and the storage unit, as well as the pulverized coal input from the pulverizing system, to achieve co-combustion of biomass and coal for power generation; The optimized scheduling method includes: Obtain a power system dispatch model; the objective function of the dispatch model is to minimize the sum of power generation cost, coal-fired unit start-up cost, carbon trading cost and curtailment penalty. The optimization variables include the start-up status of each coal-fired unit in the system at each time point, the net carbon dioxide emissions of each coal-fired unit, the amount of renewable energy curtailed by each renewable energy unit, the input and output of each pyrolysis product and the amount of biochar stored in the storage device of each coal-fired unit, the input of pulverized coal in the boiler, and the input of biomass fuel in the pyrolysis device. Solve the scheduling model under constraints to obtain the optimal scheduling decision; The constraints include: mass conservation constraints and dynamic inventory balance constraints; the mass conservation constraints include: for each pyrolysis product in any coal-fired unit, at each moment, the sum of its generation in the corresponding pyrolysis unit and its net output in the corresponding storage unit is equal to its consumption in the corresponding boiler; the dynamic inventory balance constraints include: for each pyrolysis product in any storage unit, its storage amount at each moment is equal to the difference between the storage amount at the previous moment and the net output at this moment.

2. The method for optimal dispatch of a power system comprising a biomass co-fired coal unit of claim 1, wherein, The objective function is: in, Indicates the scheduling period; This indicates the number of coal-fired power units in the power system; Represents the first in the power system Unit mass coal cost of a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The unit mass biomass fuel cost of a coal-fired power unit; For the first Enter the number at the current time Biomass fuel quality of the pyrolysis unit of each coal-fired power unit; For the first The cost of starting up a single coal-fired power unit; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; This represents the unit mass carbon emission trading cost; For the first The coal-fired power unit was in the first Net carbon dioxide emissions at a given time; This indicates the number of renewable energy units in the power system; Indicates the first in the power system Unit renewable energy curtailment penalty for each renewable energy unit; Indicates the first The renewable energy unit was in the first The amount of renewable energy power curtailed at the current moment.

3. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to claim 1, characterized in that, The mass conservation constraints include: The dynamic inventory balance constraints include: in, , , The first The first moment in the power system at this time The output of syngas, pyrolysis oil, and biochar in the pyrolysis unit of a coal-fired power plant; and They were respectively in the second At this moment The output and input of syngas in the storage device of each coal-fired unit; , , The first At this moment The consumption of syngas, pyrolysis oil, and biochar in the boilers of each coal-fired unit; and The first At this moment The output and input of pyrolysis oil in the storage device of each coal-fired unit; and The first At this moment The output and input of biochar in the storage device of each coal-fired unit; For the first At this moment The amount of biochar stored in the storage device of each coal-fired unit; , , They are respectively At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; and These are the self-loss rates of syngas and pyrolysis oil, respectively. ; This indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

4. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to claim 1, characterized in that, No. The coal-fired power unit was in the first Net carbon dioxide emissions at the current time The calculation formula is: in, Indicates the first Carbon emission factors of pulverized coal in a coal-fired power unit; Indicates the first Enter the number at the current time The quality of pulverized coal in the boilers of a coal-fired unit; Indicates the first The coal-fired power unit was in the first The amount of carbon dioxide emissions reduced by storing biochar at present; ; Indicates the first The amount of carbon dioxide emissions reduced per unit mass of biochar stored in a coal-fired power unit; Indicates the first At this moment The mass of biochar produced by biomass fuel pyrolysis in each coal-fired unit; ; This indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

5. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to any one of claims 1-4, characterized in that, The constraints also include: upper and lower limits for inventory levels, specifically including: in, , , The first At this moment The storage capacity of syngas, pyrolysis oil and biochar in the storage devices of each coal-fired unit; , , The first The capacity of the syngas, pyrolysis oil, and biochar storage devices in the storage units of each coal-fired power unit; ; This indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

6. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to any one of claims 1-4, characterized in that, The constraints also include: operational constraints on the pyrolysis unit in the coal-fired power unit; No. The operational constraints of the pyrolysis unit of a coal-fired power plant include: Among them, superscript Indicates the types of pyrolysis products; The time indicates syngas; The time indicates pyrolysis oil; The time indicates biochar; For the first The first moment in the power system at this time Pyrolysis products in the pyrolysis unit of a coal-fired power unit The output; Indicates the first The pyrolysis products generated per unit mass of biomass fuel in the pyrolysis unit of a coal-fired power unit The yield; Indicates the first At this moment The rate at which the pyrolysis unit of a coal-fired power plant processes biomass fuel; Indicates the first At this moment Energy consumption of the pyrolysis unit of a coal-fired power plant; Indicates the first Energy required for pyrolysis of a unit mass of biomass fuel in the pyrolysis unit of a coal-fired power plant; For the first The pyrolysis unit of the coal-fired power plant is in the first Indicator variables for startup at the current time. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Start at any time Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Do not start at any time; For the first Start-up energy consumption of the pyrolysis unit of a coal-fired power plant; It is an instruction for the first The pyrolysis unit of the coal-fired power plant is in the first The binary variable representing the running state at a given moment. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Always online; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first Offline at all times; and They represent the first The upper and lower limits of the rate at which the pyrolysis unit of a coal-fired power plant processes biomass fuel; For the first Indicator variables for biomass indirect co-firing retrofit of coal-fired power units Indicates the first Several coal-fired power units have undergone biomass co-firing retrofitting. Indicates the first The coal-fired power units have not undergone biomass co-firing retrofitting; It is the first The pyrolysis unit of the coal-fired power plant is in the first The indicator variable for when the machine stops. Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine is always shut down; Indicates the first The pyrolysis unit of the coal-fired power plant is in the first The machine never stopped running; and The first The pyrolysis unit of the coal-fired power plant is in the first The shortest time span between being in running and stopped states at any given moment; Indicates the scheduling period; It is the first during the scheduling period The maximum number of times a coal-fired power unit's pyrolysis unit can be started; For the first The pyrolysis unit of the coal-fired power plant is in the first It is constantly supplied to the corresponding boiler to replace the energy of the pyrolysis products of pulverized coal; , and The lower heating values ​​are syngas, pyrolysis oil, and biochar, respectively. , , The first At this moment The consumption of syngas, pyrolysis oil, and biochar in the boilers of each coal-fired unit; ; This indicates the number of coal-fired power units in the power system; .

7. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to any one of claims 1-4, characterized in that, The constraints also include: operational constraints on boilers in coal-fired power units; No. The operating constraints of the boilers in each coal-fired unit include: in, In the first At any time without burning biomass Boiler efficiency of a coal-fired unit; For the first The lower heating value of pulverized coal in the boiler of a coal-fired unit; In the first Enter the number at the current time The quality of power coal for the boilers of each coal-fired unit; For the first The pyrolysis unit of the coal-fired power plant is in the first It is constantly supplied to the corresponding boiler to replace the energy of the pyrolysis products of pulverized coal; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; and They represent the first Minimum and maximum input power of the boilers of each coal-fired unit; and The first Minimum continuous online operation and downtime of each coal-fired power unit; To indicate the first The first coal-fired unit The binary variable that is currently halted. Indicates the first The first coal-fired unit Stop the machine at any time; Indicates the first The first coal-fired unit The machine is not shut down at the moment; Indicates the first The coal-fired power unit was in the first The startup status at any given moment; Indicates the first The coal-fired power unit was in the first Start at any time; Indicates the first The coal-fired power unit was in the first Not currently running; and The first The rate of upward and downward ramping of the boilers in a coal-fired unit; and The first Operating capacity of boilers for each coal-fired power unit during startup and shutdown; For the first The boiler of the coal-fired unit was in the... Biomass co-firing rate at the current time; For the first The upper limit of the indirect co-firing rate of biomass in the boilers of a coal-fired unit; For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For the first At this moment Boiler efficiency when coal-fired units are indirectly coupled and co-fired; Indicates the first At this moment Energy consumption of the pyrolysis unit of a coal-fired power plant; and The first The maximum and minimum input thermal power of the steam turbine in a coal-fired unit; For the first At this moment Boiler efficiency of a coal-fired unit; Indicates the first Boiler efficiency of a coal-fired unit without co-firing biomass. It is the slope of the boiler efficiency as a function of the co-firing rate; ; This indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

8. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to any one of claims 1-4, characterized in that, The constraints also include: turbine operation constraints in coal-fired power units; No. The operating constraints of the steam turbines in a coal-fired power unit include: in, For the first At this moment The boiler input thermal power to the steam turbine of each coal-fired unit; For use in the first The number of nodes in the segmentation of the output curve of each coal-fired unit. The output curves of the coal-fired units were... Each node is divided into The first node corresponds to the minimum input thermal power of the steam turbine, and the last node corresponds to the maximum input thermal power of the steam turbine. As a continuous auxiliary variable, it represents the first... The coal-fired power unit was in the first The moment The weight of each node in the turbine power and generator power. It is a non-negative number; For the first The first coal-fired unit Thermal power at each node; For the first The coal-fired power unit was in the first The electrical power output at a given time; For the first The first coal-fired unit Electrical power at each node; A binary auxiliary variable used to indicate the first... At this moment Is the turbine operating status of the coal-fired power unit at the [number]th [location]? Section; when Time indicates the first At this moment The turbine operating status of the coal-fired unit is in the [missing information]. Section; when Time indicates the first At this moment The turbine operating status of the coal-fired power unit is not in the [number]th [position]. part; To indicate the first The coal-fired power unit was in the first The binary variable representing the online status at any given time. Indicates the first At this moment The boilers of each coal-fired unit are operating online. Indicates the first At this moment The boilers of one coal-fired unit are offline; ; This indicates the number of coal-fired power units in the power system; ; Indicates the scheduling period.

9. The optimized dispatching method for a power system including biomass-co-fired coal-fired units according to any one of claims 1-4, characterized in that, The constraints also include: system reserve constraints, power balance constraints, renewable energy unit output constraints, and line power flow constraints.

10. An electric power system, characterized in that, include: Biomass-co-fired power units, renewable energy units, transmission lines and controllers; The biomass-co-fired power unit includes: a pyrolysis unit, a storage unit, and a boiler; the pyrolysis unit is used to pyrolyze the input biomass fuel to obtain pyrolysis products including pyrolysis oil, syngas, and biochar; the storage unit is used to store the pyrolysis products input from the pyrolysis unit and control the output of these products to the boiler; the boiler is used to receive the pyrolysis products input from the pyrolysis unit and the storage unit, as well as pulverized coal input from the pulverizing system, to achieve co-combustion power generation of biomass and coal; The controller is used to execute the optimized scheduling method for a power system including biomass co-fired coal-fired units as described in any one of claims 1-9.

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