A method for quickly determining marginal carbon emission price of power system node

Abstract

The application belongs to the technical field of electrical engineering and relates to a method for quickly determining a node marginal carbon emission price of a power system, comprising the following steps: comprehensively solving a model SCUC and a model SCED to obtain all unit output curves and power prices of each node at each time; changing a target function of the model SCED to be solved again to obtain power prices of each node at each time containing a marginal carbon emission price component; wherein, a price generated by a single time single thermal power unit carbon emission amount is multiplied by a coefficient to be added to a single thermal power unit single time operation cost and start-up cost as a cost item; the coefficient is small, and all unit output curves obtained by solving are not changed; the two kinds of power prices of each node at each time obtained by calculation are subtracted and then divided by the above coefficient to analyze a price generated by the marginal carbon emission amount of the node at the time, and the application can quickly analyze the related price.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field related to electrical engineering, and more particularly, relates to a method for quickly determining a marginal carbon emission price of a node of a power system. BACKGROUND

[0002] Low-carbon transformation of a power system is a problem that needs to be solved at present. Carbon price, as a market price signal, can guide market users to actively respond, thereby reducing system carbon emissions. However, most current power systems calculate carbon emission values based on average carbon emission rates, which is difficult to reflect real-time carbon emission values of each node of the power system, thereby making it difficult to guide users to respond to prices through price signals. In addition, in actual large power systems, it is difficult to quickly analyze the marginal carbon emission price of the node by using conventional methods, which hinders the reduction of carbon emissions of the power system. SUMMARY

[0003] In view of the above defects or improvement needs of the prior art, the application provides a method for quickly determining a marginal carbon emission price of a node of a power system, which aims to quickly analyze the marginal carbon emission price of the node, thereby providing a carbon emission price signal for power market users, guiding users to respond to the demand side, and promoting low-carbon transformation of the power system.

[0004] To achieve the above-mentioned purpose, according to one aspect of the application, a method for quickly determining a marginal carbon emission price of a node of a power system is provided, comprising:

[0005] solving a security constrained unit commitment model SCUC of the power system to obtain generator set start-stop states; fixing the generator set start-stop states, solving a security constrained economic dispatch model SCED of the power system to obtain all unit output curves in the power system and power prices of each node at each time:

[0006] changing the objective function in the SCED, the constraint condition being unchanged, solving a linear programming problem again to obtain power prices of each node at each time containing a marginal carbon emission price component: wherein the changing mode is that the price generated by the carbon emission of a single thermal power unit at a single time is multiplied by a coefficient to be added to the operation cost and the start-up cost of the single thermal power unit at the single time, and the sum of the addition results of all times and all thermal power units is summed up as a new objective function; the coefficient has a small value, and satisfies that the price generated by the carbon emission of the thermal power unit accounts for a small proportion in the objective function, and does not change all unit output curves obtained by solving;

[0007] The electricity price at each node at each time point, which includes the marginal carbon emission price component, is subtracted from the electricity price without the marginal carbon emission price component. The resulting difference in electricity prices is then divided by the coefficient mentioned above. This yields the price generated by the marginal carbon emission at that node at that time point, thus completing the marginal carbon emission price for that node at that time point. This price represents the price corresponding to the additional carbon emissions generated by the power system when the load at that node increases.

[0008] Furthermore, the constraints of the Safety Constrained Unit Combination Model (SCUC) include: system load balance constraints, unit output upper and lower limit constraints, line power flow constraints, minimum start-up and shutdown time constraints for thermal power units, maximum uphill and downhill ramp rates constraints for thermal power units, and positive and negative reserve capacity constraints for units.

[0009] The objective function of the Safety Constraint Unit Combination Model (SCUC) is to minimize the total generation cost, expressed as:

[0010]

[0011] in, Indicates the total number of time periods. , They represent thermal power units At any moment Operating costs and start-up costs, This indicates the number of thermal power units.

[0012] Furthermore, the constraints and objective function of the Safety Constrained Economic Scheduling (SCED) model are the same as those of the SCUC model.

[0013] Furthermore, the electricity price at each node at each time point is expressed as follows:

[0014]

[0015] in, Represents a node k At any moment t Electricity prices; Indicates time Load balance constraint Lagrange multipliers; , They represent the lines respectively. At any moment t Maximum positive and negative current flow constraints Lagrange multipliers; L This indicates the total number of tie lines in the power system; Indicates the node where the load is located. k With connecting lines The power flow distribution transfer factor, superscript kG is an auxiliary mark of the thermal power unit, which is used to distinguish from the node where the thermal power unit is located, the node where the renewable energy unit is located, and the node where the transmission line outside the region is located and the tie line power flow distribution transfer factor.

[0016] Further, the new objective function is expressed as:

[0017]

[0018] In the formula, G represents the thermal power unit carbon emission coefficient, unit: tCO2 / MWh, G represents power generation in the time, unit: MWh, G represents total carbon emissions; G represents the unit price of carbon emissions; G represents the coefficient.

[0019] According to another aspect of the present application, an electronic device is provided, comprising a memory and a processor, the memory stores a computer program, and the processor implements the steps of the method as described above when executing the computer program.

[0020] According to another aspect of the present application, a computer readable storage medium is provided, comprising a stored computer program, wherein the computer program controls the device where the storage medium is located to execute the steps of the method as described above when the computer program is run by a processor.

[0021] According to another aspect of the present application, a computer program product is provided, comprising a computer program or instructions, which implement the steps of the method as described above when executed by a processor.

[0022] Overall, compared with the prior art, the technical scheme provided by the present application mainly has the following beneficial effects:

[0023] 1. The present application proposes a method for calculating the marginal carbon emission price of nodes in a large power system. The marginal carbon emission price of nodes obtained by the method can be used to replace the average carbon emission price currently used to guide the price response of power users, which is conducive to the transmission of the carbon emission value signal of the power system and can further reduce the carbon emission of the power system through user-side response. The method first adds a small coefficient to the carbon emission cost of thermal power units in the objective function based on the security constrained unit commitment model SCUC and the security constrained economic dispatch model SCED currently used by power dispatching institutions, so as to ensure that all the obtained unit output curves are not changed and the carbon emission information of the power system is reflected in the Lagrange multiplier of the optimization model. Based on the power price containing the carbon emission price component and the power price not containing the price component, the price generated by the marginal carbon emission of each node at each time is analyzed, so that the power grid dispatching department can quickly and efficiently obtain the marginal carbon emission price of each node under the current power system operation mode. The method can obtain the marginal carbon emission price of each node for guiding the user-side response and meet the technical requirements of the actual power dispatching institution for quickly calculating the carbon emission price of each node in the large power system. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flow chart of a method for quickly determining the marginal carbon emission price of nodes in a power system is provided for the embodiments of the present application.

[0025] Figure 2 A generator set capacity statistical diagram of each node in a power system is provided for the embodiments of the present application.

[0026] Figure 3 A maximum transmission capacity statistical diagram of transmission lines between nodes in a power system is provided for the embodiments of the present application.

[0027] Figure 4 An average load statistical diagram of each node in a power system is provided for the embodiments of the present application.

[0028] Figure 5 A carbon emission price distribution of each node based on the average carbon emission coefficient is provided for the embodiments of the present application.

[0029] Figure 6 A carbon emission price distribution of each node based on the marginal carbon emission price of nodes is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0030] In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0031] Embodiment one

[0032] A method for quickly determining the marginal carbon emission price of a power system node, as shown in the formula (1), comprises the following steps: Figure 1

[0033] solving a security constrained unit commitment (SCUC) model of the power system to obtain the start-stop state of the generator unit; fixing the start-stop state of the generator unit, solving a security constrained economic dispatch (SCED) model of the power system to obtain the output curve of all generator units in the power system and the power price of each node at each time point:

[0034] changing the objective function in the SCED, and keeping the constraint condition unchanged, solving the linear programming problem again to obtain the power price of each node at each time point containing the marginal carbon emission price component: wherein the changing manner is that the price generated by the carbon emission of a single thermal power generator unit at a single time point is multiplied by a coefficient to form a cost item, which is added to the operation cost and start-up cost of the single thermal power generator unit at the single time point, and the sum of the addition results of all time points and all thermal power generator units is taken as a new objective function; the value of the coefficient is small, and meets that the price generated by the carbon emission of the thermal power generator unit accounts for a small proportion in the objective function, and does not change all the obtained output curves of the generator units;

[0035] subtracting the power price not containing the marginal carbon emission price component from the calculated power price of each node at each time point containing the marginal carbon emission price component, and dividing the obtained power price difference by the coefficient, that is, the price generated by the marginal carbon emission at the node at the time point is analyzed, and the marginal carbon emission price at the node at the time point is completed, which represents the price corresponding to the additional carbon emission of the power system when the unit load at the node is increased.

[0036] ​This embodiment proposes a method for calculating the marginal carbon emission price at nodes in a large power system. The analytically derived marginal carbon emission price can replace the currently used average carbon emission price, guiding electricity users in price responses and facilitating the transmission of electricity carbon emission value signals. This can further reduce power system carbon emissions through user-side responses. Firstly, based on the Safety Constrained Unit Combination Model (SCUC) and the Safety Constrained Economic Dispatch Model (SCED) currently used by power dispatching agencies, this method multiplies the carbon emission cost of thermal power units by a small coefficient and incorporates it into the objective function. This allows the carbon emission information of the power system to be reflected in the Lagrange multipliers of the optimization model without altering the output curves of all units obtained. Based on electricity prices including and excluding carbon emission price components, the method analyzes the price generated by the marginal carbon emissions at each node at each time point, enabling the grid dispatching department to quickly and efficiently obtain the marginal carbon emission price of each node under the current power system operating mode. This method not only obtains the marginal carbon emission price of each node to guide user-side responses but also meets the technical requirements of practical power dispatching agencies for rapidly calculating the carbon emission prices of each node in a large power system.

[0037] The mathematical models for calculating Security Constrained Unit Combination (SCUC) and Security Constrained Economic Dispatch (SCED) in the current power system spot market can be expressed as a mixed-integer linear programming model.

[0038] As a preferred option, the constraints of the Safety Constraint Unit Combination Model (SCUC) include: system load balance constraints, unit output upper and lower limit constraints, line power flow constraints, minimum start-up and shutdown time constraints for thermal power units, maximum uphill and downhill ramp rate constraints for thermal power units, and positive and negative reserve capacity constraints for units.

[0039] Specifically, the system load balance constraint can be expressed as:

[0040] (1)

[0041] in, , , They represent the first The thermal power unit, renewable energy unit, and the connection line between the solution area and the outside world are at time... of effort. Indicates time Electrical load. , , These represent the number of thermal power units, renewable energy units, and the number of connection lines between the solution area and the outside world, respectively.

[0042] The positive and negative reserve capacity constraints of the generating unit can be expressed as:

[0043] (2)

[0044] (3)

[0045] where, is the thermal power unit i at time t , 0 for shutdown and 1 for startup. , is the thermal power unit i maximum and minimum output coefficients. , is the thermal power unit i and the installed capacity of renewable energy units i . is the renewable energy unit i at time t capacity factor. , are the system positive and negative reserve capacity requirements respectively within time t .

[0046] The upper and lower limits of unit output constraints can be expressed as:

[0047] (4)

[0048] (5)

[0049] The maximum up and down ramp rate constraints of thermal power units can be expressed as:

[0050] (6)

[0051] (7)

[0052] where, , are the maximum up and down ramp rates of thermal power units .

[0053] The minimum startup and shutdown time constraints of thermal power units can be expressed as:

[0054] (8)

[0055] (9)

[0056] where, , are the minimum continuous startup time and minimum continuous shutdown time of thermal power units respectively. , respectively, are the nodes where thermal power units are located, At time period t The time of continuous start-up and shut-down can be expressed as:

[0057] (10)

[0058] (11)

[0059] The power flow constraint of the line can be expressed as:

[0060] (12)

[0061] wherein, is the power flow transmission limit of the line , , , , are the power flow distribution transfer factors of the nodes where thermal power units are located, the nodes where renewable energy units are located, the nodes where transmission lines outside the region are located, and the nodes where loads are located, respectively, and the tie line. is the number of system nodes. is the bus load of the node at time t .

[0062] The objective function of the security constrained unit commitment model SCUC is to minimize the total generation cost, which is expressed as:

[0063] (13)

[0064] wherein, represents the total number of time periods, , represent the operation cost and the start-up cost of the thermal power unit at time , respectively; is a multi-segment linear function related to the output interval and the corresponding price of each time period declared by the thermal power unit.

[0065] The load balance constraint, the unit output constraint, the upper and lower limit constraint, the line power flow constraint, the cross-section power flow constraint, and the objective function of the security constrained economic dispatch model SCED are the same as those of the SCUC model. After the security constrained unit commitment model is solved, the start-up and shut-down states of the thermal power units are fixed , and the model is converted from a mixed integer linear programming to a general linear programming. The general linear programming model is the security constrained economic dispatch model. By solving the linear programming model, the power price at each node at each time is calculated.

[0066] The power price at each node at each time is expressed as:

[0067]

[0068] where, denotes the node k The electricity price in time period t ; denotes the time The load balance constraint Lagrange multiplier; , denotes the line The maximum forward, reverse flow constraint Lagrange multiplier in time period t ; L denotes the number of all link lines in the power system; denotes the node k The load is located in the node The flow distribution transfer factor of the tie line k The superscript G is the auxiliary mark to distinguish the flow distribution transfer factor of the tie line between the node where the thermal power unit is located, the node where the renewable energy unit is located and the node where the regional transmission line is located.

[0069] After calculating the safe constraint economic dispatch, the price of carbon emissions generated by each node of each time thermal power unit is multiplied by a small coefficient to add to the objective function, that is, the objective function is changed to:

[0070] (15)

[0071] where, denotes the carbon emission coefficient of thermal power unit , unit tCO2 / MWh, denotes the power generation in time, unit MWh, denotes the total carbon emission; denotes the unit price of carbon emission; denotes the above-mentioned small coefficient, the default value, when The carbon emission cost in the objective function is very small and will not change the power dispatching result, but the carbon emission price will be reflected in the Lagrange multiplier of each constraint condition.

[0072] Taking formula (15) as the objective function, the linear programming model is solved again, and the node price containing the carbon emission price component can be obtained by formula (14) . On this basis, the carbon emission price of each node at each time can be calculated:

[0073] (16)

[0074] The price The marginal carbon emission price of the power system node (ca: carbon, yuan / MWh) is obtained by modifying the objective function and re-solving the security constrained economic dispatch model once. The price represents the price corresponding to the additional carbon emissions generated by the power system when the unit load at the node is increased. Compared with the average carbon emission price calculated by the average carbon emission rate of the power system, the node marginal carbon emission price can reflect the time and space characteristics and can better guide market users to carry out load response.

[0075] The embodiment provides a carbon market mechanism based on carbon emission intensity, and a carbon quota transaction decision optimization model of a power generation enterprise market subject in the power industry. In general, the method comprises the following steps:

[0076] Step 1: Calculate the start-stop arrangement of the generator set based on the security constrained unit commitment model (SCUC).

[0077] Step 2: After determining the start-stop of the unit, solve the security constrained economic dispatch model (SCED) to obtain the unit output curve and node price.

[0078] Step 3: Change the objective function, and re-solve the linear programming model to obtain the node marginal price including the carbon emission price component.

[0079] Step 4: Calculate the node marginal carbon emission price.

[0080] An implementation case is given as follows:

[0081] A real power system in a certain region is taken as an example for analysis. It is assumed that the region has 14 nodes, the installed capacity of the generator set of the power system at each node is as shown in Figure 2 , the maximum transmission capacity of the transmission line between the nodes of the power system is as shown in Figure 3 , and the average load of each node of the power system is as shown in Figure 4 . It is assumed that the carbon tax price is 100 yuan / ton, and the simulation is performed for 8760 time periods in a year. The carbon emission price distribution of the 8760 time periods in a year based on the average carbon emission rate and the node marginal carbon emission price is as shown in Figure 5 and Figure 6 .

[0082] Figure 5 The carbon price distribution of each node at each time based on the average carbon emission coefficient of each node is shown. Due to the high renewable energy installed capacity of some nodes, the average carbon emission coefficient is lower than that of other nodes, resulting in significant differences in carbon prices at different nodes at different times. Figure 6The distribution of marginal carbon emission price of each node is presented, which represents the price cost paid by the power system for the additional carbon dioxide emission when the node increases unit load. Due to the abundant transmission channels between nodes, the marginal units of each node are the same most of the time, so the carbon emission prices of each node are small. The marginal carbon emission price of each node reflects the marginal value of carbon emission of the power system rather than the average value, which can more effectively guide the price response of the user side.

[0083] Embodiment two

[0084] The application also relates to an electronic device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the steps of the above method when executing the computer program.

[0085] The electronic device can be a desktop computer, a notebook computer, a palm computer, a cloud server and the like. The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components and the like. The memory can be used to store computer programs and / or modules, and the processor can implement various functions of the electronic device by running or executing the computer programs and / or modules stored in the memory, and calling data stored in the memory.

[0086] The related technical solutions are the same as above, and will not be repeated here.

[0087] Embodiment three

[0088] The application also relates to a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the above method.

[0089] Specifically, the memory can include a high-speed random access memory, and can also include a non-volatile memory, for example, a hard disk, a memory, a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, at least one magnetic disk storage device, a flash memory device or other volatile solid-state memory device.

[0090] The related technical solutions are the same as above, and will not be repeated here.

[0091] Embodiment Four

[0092] The embodiment of the present application provides a computer program product or computer program, the computer program product or computer program comprising computer instructions stored in a computer readable storage medium. The processor of the computer equipment reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer equipment executes the steps of the method of the above-mentioned embodiments of the present application.

[0093] The related technical solutions are the same as above, and will not be repeated here.

[0094] Those skilled in the art can easily understand that the above description is only the preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for rapidly determining the marginal carbon emission price at power system nodes, characterized in that, include: Solve the safety-constrained unit combination model (SCUC) of the power system to obtain the start-up and shutdown states of the generator units; fix the start-up and shutdown states of the generator units, solve the safety-constrained economic dispatch model (SCED) of the power system to obtain the output curves of all units in the power system and the electricity price at each node at each time point: The objective function in SCED is modified while the constraints remain unchanged. The linear programming problem is solved again to obtain the electricity price at each node at each time point, including the marginal carbon emission price component. The modification is as follows: the price generated by the carbon emissions of a single thermal power unit at a single time point is multiplied by a coefficient and added as a cost item to the operating cost and start-up cost of the single thermal power unit at a single time point. The sum of the sums over all time points and all thermal power units is used as the new objective function. The coefficient is small enough to satisfy the condition that the price generated by the carbon emissions of thermal power units accounts for a small proportion of the objective function, without changing the output curves of all units obtained by the solution. The electricity price at each node at each time point, which includes the marginal carbon emission price component, is subtracted from the electricity price without the marginal carbon emission price component. The resulting difference in electricity prices is then divided by the coefficient mentioned above. This yields the price generated by the marginal carbon emission at that node at that time point, thus completing the marginal carbon emission price for that node at that time point. This price represents the price corresponding to the additional carbon emissions generated by the power system when the load at that node increases.

2. The method as described in claim 1, characterized in that, The constraints of the Safety Constraint Unit Combination Model (SCUC) include: system load balance constraints, unit output upper and lower limit constraints, line power flow constraints, minimum start-up and shutdown time constraints for thermal power units, maximum uphill and downhill ramp rate constraints for thermal power units, and positive and negative reserve capacity constraints for units. The objective function of the Safety Constraint Unit Combination Model (SCUC) is to minimize the total generation cost, expressed as: ,in, Indicates the total number of time periods. , They represent thermal power units At any moment Operating costs and start-up costs, This indicates the number of thermal power units.

3. The method as described in claim 1, characterized in that, The constraints and objective function of the Safety-Constrained Economic Scheduling (SCED) model are the same as those of the SCUC model.

4. The method as described in claim 1, characterized in that, The electricity price at each node at each time point is expressed as follows: ,in, Represents a node k At any moment t Electricity prices; Indicates time Load balance constraint Lagrange multipliers; , They represent the lines respectively. At any moment t Maximum positive and negative current flow constraints Lagrange multipliers; L This indicates the total number of tie lines in the power system; Indicates the node where the load is located. k With connecting lines The power flow distribution transfer factor, superscript k This is an auxiliary marker for G, used to distinguish it from the nodes where thermal power units are located, renewable energy units are located, and external transmission lines and tie lines are located. The power flow distribution transfer factor.

5. The method as described in claim 3, characterized in that, The new objective function is expressed as: In the formula, Indicates thermal power unit Carbon emission factor, expressed in tCO2 / MWh. express Electricity generated within a given time period, expressed in MWh. Indicates total carbon emissions; Indicates the unit price of carbon emissions; This represents the coefficient.

6. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 5.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein the computer program, when executed by a processor, controls the device on which the storage medium is located to perform the steps of the method as described in any one of claims 1 to 5.

8. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed by a processor, they implement the steps of the method as described in any one of claims 1 to 5.

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