A real-time calculation method for carbon emission flow in power system

Abstract

The present invention discloses a real-time calculation method for carbon emission flow of power system, obtains the real-time node load, generator power, network topology and related technical parameters of the system; uses Newton-Raphson method to calculate the AC power flow equation, obtains the voltage amplitude and angle of each node, and then calculates the active power and loss of each branch; constructs the upstream distribution matrix, and then apportions the generator power to obtain the generator power component corresponding to each node load, each branch active power and loss; calculates the real-time carbon emission intensity of each unit according to the active power of the generator set; apportions the unit carbon emission to obtain the generator carbon emission rate component corresponding to each node load, each branch active power and loss. The carbon emission flow calculation method proposed in the present invention can accurately calculate the real-time carbon flow distribution of the power system, reasonably divide the carbon emission responsibilities of different entities, and has good practical value for formulating carbon reduction measures and promoting low-carbon development of electricity.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a real-time calculation method for carbon emission flow of a power system. Background Art

[0002] As energy crisis and climate issues become increasingly prominent, achieving low-carbon sustainable development and reducing excessive energy consumption have become a general consensus of the whole society. As one of the main sources of carbon emissions, the power system accounts for about 36.08% of the total carbon dioxide emissions in the whole society, facing unprecedented pressure to reduce carbon emissions. In order to achieve low-carbon development of electricity, it is particularly important to carry out carbon emission analysis and statistics.

[0003] At present, there are two main methods for calculating carbon emissions in power systems: macro-statistics and carbon flow analysis. Among them, the macro-statistics method starts from macro data and performs statistics based on energy consumption. It has the advantages of simple calculation and easy use. However, the calculation results of this method are too rough and cannot track the specific flow of carbon emissions, which is not conducive to the division and identification of carbon emission responsibilities. The carbon flow analysis method is combined with the flow analysis to realize carbon flow analysis by introducing concepts such as node carbon potential, carbon flow rate, and emission intensity, but it cannot consider network losses and has poor calculation accuracy.

[0004] In view of this, the present invention proposes a real-time calculation method for carbon emission flow of a power system. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a real-time calculation method for carbon emission flow of power system, which takes the AC power flow calculation result as input, and based on the proportional distribution principle, adopts the power flow sharing algorithm to split the generator power into each node load, each branch power and loss; then combines the real-time carbon emission rate model of different generators and the generator power distribution to realize the real-time measurement and reasonable sharing of carbon emissions of power system.

[0006] To achieve the purpose of the present invention, the technical solution adopted by the present invention is:

[0007] A method for real-time calculation of carbon emission flow of a power system, the method comprising the steps of:

[0008] (1) Obtain system real-time node load, generator power, network topology and related technical parameters;

[0009] (2) Use the Newton-Raphson method to calculate the AC power flow equation, obtain the voltage amplitude and angle of each node, and then calculate the active power P of each branch ij and loss

[0010] (3) Constructing the upstream distribution matrix A u, and then the generator power is apportioned to obtain the generator power component P corresponding to each node load, each branch active power and loss Lk，Gi , P kj，Gi and

[0011] (4) According to the active power P of the generator set Gi , calculate the real-time carbon emission intensity E of each unit Gi ;

[0012] (5) Allocate the unit carbon emissions to obtain the generator carbon emission rate component R corresponding to each node load, each branch active power and loss Lk,Gi , R kj,Gi and

[0013] Furthermore, in the step (1), the real-time node load of the system is obtained, including active load and reactive load, and the generator power includes active power and reactive power;

[0014] Relevant technical parameters include the technical parameters and operating status of lines, transformers, and switchgear, the type, capacity, carbon capture rate, carbon content of coal, and coal consumption characteristics per kilowatt-hour of power generation units.

[0015] Furthermore, in step (2), the active power and loss of each branch are calculated, that is:

[0016] P ij =V i V j (G ij cosδ ij +B ij sinδ ij ) (3)

[0017]

[0018] Where P ij is the active power flowing through branch ij, and its positive direction is from node i to node j; is the active power loss of branch ij.

[0019] Furthermore, in step (3), A u ∈R n×n is the upstream distribution matrix, and its elements are calculated as follows:

[0020]

[0021] In the formula, [A u ] ji Represents the matrix A u The element at row j and column i in .

[0022] Furthermore, in step (3), the power share P drawn by the node k load from the node i generator is Lk，Li for:

[0023]

[0024] The generator connected to node i is kj Contribution share P kj，Gi for:

[0025]

[0026] The generator pair connected to node i Contribution share for:

[0027]

[0028] In the formula, e i ∈R n×1 is a column vector whose i-th component is 1 and the rest are 0.

[0029] Furthermore, in step (3), according to the node power conservation principle, that is, the active power flowing through the node is equal to the total active power flowing into the node, the upstream distribution matrix A is constructed. u ;

[0030] According to the principle of node power conservation, the active power flowing through the node is equal to the total active power flowing out of the node, and the generated power is allocated to each node load, each branch active power and loss.

[0031] Furthermore, in step (4), the carbon emission intensity E of the unit Gi The calculation formula is:

[0032]

[0033] In the formula, is the molar mass of carbon dioxide; M C is the molar mass of carbon; η i is the carbon content of the coal burned in unit i; ξ i is the carbon oxidation rate of unit i; μ i is the carbon capture rate.

[0034] Furthermore, in step (5), the unit carbon emission intensity and the unit power distribution are combined, and the unit carbon emission is apportioned according to the power generation distribution to obtain the unit carbon emission share required to bear each node load, each branch active power and loss.

[0035] Furthermore, in step (5), the carbon emission rate R of unit i that the node k load needs to bear isLk,Gi for:

[0036] R Lk,Gi =P Lk,Gi E Gi (18)

[0037] The contribution of the generator connected to node i to the carbon emission rate of branch kj is R kj,Gi for:

[0038] R kj，Gi =P kj，Gi E Gi (20)

[0039] Carbon emission rate contribution of the generator connected to node i to the active power loss of branch kj for:

[0040]

[0041] The beneficial effect of the present invention is that, compared with the prior art, the carbon emission flow calculation method proposed in the present invention can accurately calculate the real-time carbon flow distribution of the power system and reasonably divide the carbon emission responsibilities of different entities, which has good practical value for formulating carbon reduction measures and promoting low-carbon development of electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a flow chart of the real-time calculation method of carbon emission flow of power system according to the present invention;

[0043] Figure 2 This is the 4-node system topology structure of the embodiment of the present invention. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of this application.

[0045] like Figure 1 As shown, the real-time calculation method of carbon emission flow of the power system described in the present invention includes five steps: real-time data acquisition, AC power flow calculation, power generation allocation, unit carbon emission calculation and real-time carbon flow analysis.

[0046] The specific steps are as follows:

[0047] (1) Real-time data acquisition: obtaining the real-time load of each node in the system (including active and reactive load), active and reactive power of generators, network topology and related technical parameters at the current moment;

[0048] The real-time load of each node and the active and reactive power of the generator are obtained from the dispatching system; the network topology of the main grid and related technical parameters are obtained from the model library, including the technical parameters (such as resistance, reactance) and operating status (operation, standby) of equipment such as lines, transformers, and switches; the type, capacity, carbon capture rate, carbon content of coal, and coal consumption characteristics of the generator set are obtained from the equipment library.

[0049] (2) AC power flow calculation: The Newton-Raphson method is used to calculate the AC power flow equation, obtain the voltage amplitude and angle of each node, and then calculate the active power P of each branch. ij and loss

[0050] According to the real-time data provided in step (1), the Newton-Raphson method is used to calculate the AC power flow equation to obtain the voltage amplitude V of each node i and angle δ i .

[0051] AC power flow equation:

[0052]

[0053]

[0054] Where P Gi , Q Gi are the active and reactive power of the generator connected to node i, in MW and MVar respectively; P Li , Q Li are the active and reactive loads of access node i, in MW and MVar respectively; G ij , B ij are the negative values ​​of the conductance and susceptance of branch ij respectively; U i and δ i are the voltage amplitude and angle of node i, δ ij =δ i -δ j .

[0055] According to the voltage amplitude and angle obtained by power flow calculation, the active power and loss of each branch are calculated by combining equations (3) and (4), namely:

[0056] P ij =V i V j (G ij cosδ ij +B ij sinδ ij ) (3)

[0057]

[0058] Where P ij is the active power flowing through branch ij, and its positive direction is from node i to node j; is the active power loss of branch ij.

[0059] (3) Power generation allocation; constructing the upstream distribution matrix A u , and then the generator power is apportioned to obtain the generator power component P corresponding to each node load, each branch active power and loss Lk,Gi , P kj,Gi and

[0060] (3.1) According to the principle of node power conservation, that is, the active power flowing through the node is equal to the total active power flowing into the node, the active power flowing through node j can be expressed as:

[0061]

[0062] Where P j is the active power flowing through node j, which is equal to the power injection power P of node j Gj The active power flowing into each upstream node |P ji |(Active power of each branch P ji The absolute value of j is the set of upstream nodes of node j, that is, the set of nodes that are directly connected to node j and whose power flows into node j.

[0063] Rewrite equation (5) as:

[0064]

[0065] Where P i is the active power flowing through the upstream node i.

[0066] Formula (6) can be expressed in the following matrix form:

[0067] A u P=P G (7)

[0068] Where P G is the vector formed by the active power of the generators at each node; P = [P1 P2 … P n ] T A is the vector of active power flowing through each node; u ∈R n×n is the upstream distribution matrix, and its elements are calculated as follows:

[0069]

[0070] In the formula, [A u ] ji Represents the matrix A u The element at row j and column i in .

[0071] (3.2) Formula (7) establishes the connection between the active power of the generator and the active power flowing through the node. The active power flowing through the node is equal to the total outflow active power of the node (the sum of the load power and the active power flowing to the downstream node), and the generated power can be allocated to each node load, each branch active power and loss.

[0072] (3.2.1) The power drawn by the load from the generator; according to the proportional distribution principle, the load P of node k Lk It can be expressed as the sum of the contributions of each generator, that is:

[0073]

[0074] In the formula, e k ∈R n×1 is a column vector whose kth component is 1 and the rest are 0.

[0075] Among them, the power share P drawn by the node k load from the node i generator is Lk,Li for:

[0076]

[0077] In the formula, e i ∈R n×1 is a column vector whose i-th component is 1 and the rest are 0.

[0078] (3.2.2) The power drawn by the branch from the generator; Assuming that the power flow of branch kj is from node k to node j, then the branch active power P kj It is composed of the upstream generator power of node k, and the proportional distribution principle is:

[0079]

[0080] Among them, the generator connected to node i has a kj Contribution share P kj,Gi for:

[0081]

[0082] (3.2.3) The network loss power borne by the generator; Assuming that the power flow of branch kj is from node k to node j, then the branch active power loss is It is composed of the upstream generator power of node k, and the proportional distribution principle is:

[0083]

[0084] Similarly, the generator connected to node i Contribution share for:

[0085]

[0086] (4) Calculation of unit carbon emissions; Based on the active power P of the generator set Gi , calculate the real-time carbon emission intensity E of each unit Gi ;

[0087] The carbon emission intensity of a unit is the amount of CO2 emissions generated by the unit per unit of electricity produced, in units of tCO2 / (MW·h). Different types of units have different carbon emission intensities. For hydropower units and new energy units, the carbon emissions per unit of electricity produced are 0. For thermal power units, their carbon emission intensity is affected by factors such as unit capacity, fuel used, operating status, and load rate, and can be calculated using the following formula.

[0088] According to the current operating status and real-time power of the thermal power unit, the unit coal consumption w is calculated according to formula (15). i ,Right now:

[0089]

[0090] In the formula, a i 、b i 、c i are the characteristic parameters of the coal consumption curve of unit i under normal operation, which can be obtained by fitting historical data; i is the coal consumption per kilowatt-hour of unit i, in g / (kW·h); ζ i is the correction coefficient, and its value is related to the unit status. Under normal conditions, ζ i Take 1.0, in the shutdown state i Take 0, when deep peak load regulation and rapid load rise and fall, ζ i Take 1.01.

[0091] Unit carbon emission intensity E Gi The calculation formula is:

[0092]

[0093] In the formula, is the molar mass of carbon dioxide, i.e. 44 g / mol; M C is the molar mass of carbon, i.e. 12 g / mol; η i is the carbon content of the coal used in unit i, which can be directly obtained through elemental analysis; i is the carbon oxidation rate of unit i, the default value is 98%; μ iis the carbon capture rate.

[0094] (5) Real-time carbon flow analysis: apportion the unit carbon emissions to obtain the generator carbon emission rate component R corresponding to each node load, each branch active power and loss Lk,Gi , R kj,Gi and

[0095] Formulas (9), (11) and (13) quantitatively give the distribution of power generation among each node load, each branch active power and loss. The carbon emission intensity describes the carbon dioxide emissions per unit of electricity produced by the unit. Therefore, the unit carbon emission intensity and unit power distribution can be combined to apportion the unit carbon emissions according to the power generation distribution, thereby obtaining the unit carbon emission share required by each node load, each branch active power and loss.

[0096] (5.1) Load carbon emission rate; According to equations (9) and (16), the carbon emission rate of the node k load is:

[0097]

[0098] In the formula, R Lk is the carbon emission rate of node k load, in tCO2 / h; diag(P G ) represents the column vector P G Transformed into a diagonal matrix; E G is the carbon emission intensity vector of the unit.

[0099] Among them, the carbon emission rate R of unit i that node k load needs to bear is Lk,Gi for:

[0100] R Lk,Gi =P Lk,Gi E Gi (18)

[0101] (5.2) Branch carbon emission rate; According to equations (11) and (16), the carbon emission rate R corresponding to the power flowing through branch kj can be obtained: kj for:

[0102]

[0103] Among them, the contribution of the generator connected to node i to the carbon emission rate of branch kj is R kj,Gi for:

[0104] R kj,Gi =P kj,Gi E Gi (20)

[0105] (5.3) Network loss carbon emission rate; According to equations (13) and (16), the carbon emission rate corresponding to the active loss of branch kj can be obtained: for:

[0106]

[0107] Among them, the contribution of the generator connected to node i to the carbon emission rate of the active power loss of branch kj is for:

[0108]

[0109] A simple 4-node system is taken as an example to illustrate the method of the present invention.

[0110] (1) Real-time data acquisition;

[0111] System topology Figure 2 As shown, node 1 is a balance node, which is connected to a hydropower plant with a carbon emission intensity of 0; node 2 is a PV node, which is connected to a thermal power plant with an active output of 114MW, and the coal consumption characteristic parameters a2, b2, and c2 are 0.0010, 0.14, and 4.0, respectively, the correction parameter ζ2 = 1.0, and the carbon content η i =0.80, carbon oxidation rate ξ2 =0.98, carbon capture rate μ i =0.0; Node 3 and Node 4 are both PQ nodes, and their corresponding reactive loads are (200+j80)MVA and (300+j120)MVA respectively; the unit impedance value of each branch is 0.01938+j0.05917Ω.

[0112] (2) AC power flow calculation;

[0113] According to the parameters in step (1), the Newton-Raphson method is used to calculate the AC power flow equations (1)-(2), and the voltage and active power of each node are obtained as shown in Table 1. Then, the active power and loss of each branch are calculated according to equations (3) and (4), and the results are shown in Table 2.

[0114] Table 1

[0115] Node Number 1 2 3 4 Voltage amplitude / pu 1.0500 1.045 0.9816 0.9433 Voltage angle / rad 0.0000 -0.0104 -0.0743 -0.1165 Unit output / MW 409.3117 114.00 0.0000 0.0000 Load active power / MW 0.0000 0.0000 200.00 300.00

[0116] Table 2

[0117]

[0118] (3) Power generation apportionment;

[0119] According to Table 1-2 and equations (5) and (7), the power flowing through each node and the power generated are:

[0120] PG1 =409.3117, P G2 =114.00, P G3 =0.0000, P G4 =0.0000

[0121] P1=P G1 =409.3117

[0122] P2=P G2 +|P 21 |=114.00+20.0610=134.0610

[0123] P3=|P 31 |+|P 32 |=148.8961+129.9614=278.8575

[0124] P4=|P 41 |+|P 43 |=222.6994+77.3006=300

[0125] Then P = [409.3117, 134.0610, 278.8575, 300.00] T , P G =[409.3117, 114.00, 0.00, 0.00] T According to formula (8), the upstream distribution matrix is:

[0126]

[0127] in,

[0128] [A u ] 21 =-|P 21 | / P1=-20.0610 / 409.3117=-0.0490,

[0129] [A u ] 31 =-|P 31 | / P1=-148.8961 / 409.3117=-0.3638,

[0130] [A u ] 41 =-|P 41 | / P1=-22.6994 / 409.3117=-0.5441,

[0131] [A u ] 32 =-| 32| / P2=-129.9614 / 134.0610=-0.9694,

[0132] [A u ] 43 =-|P 43 | / P3=-77.3006 / 278.8575=-0.2772,

[0133] [A u ] 11 =[A u ] 22 =[A u ] 33 =[A u ] 44 =1.0.

[0134] According to formula (10), the contribution of the power plant to the load power of each node is shown in Table 3.

[0135] Table 3

[0136]

[0137] According to formula (12), the contribution of the power plant to the power of each branch is shown in Table 4.

[0138] Table 4

[0139]

[0140] According to formula (14), the contribution of the power plant to the losses of each branch is shown in Table 5.

[0141] Table 5

[0142]

[0143] (4) Calculation of carbon emissions of the unit;

[0144] The power plant at node 1 is a hydropower plant, and its carbon emission intensity is E G1 = 0. According to the parameters of the power plant at node 2 and formula (15), its coal consumption per kilowatt-hour can be obtained as:

[0145] w2=(0.0010×114 2 +0.14×114+4.0)×1.0 / 114×10 3 =289.087719g / (kW·h)

[0146] According to formula (15), its carbon emission intensity can be obtained as follows:

[0147] E G2 =0.80×0.98×1.0×44 / 12×289.087719 / 103 =0.831031tCO2 / (MW·h)

[0148] (5) Real-time carbon flow analysis.

[0149] The carbon emissions of the units are apportioned according to Table 3-5 and equations (18), (20), and (22), and the carbon flow rate components of the power plant corresponding to each node load, branch active power, and network loss are obtained as shown in Table 6-8.

[0150] Table 6

[0151]

[0152] Table 7

[0153]

[0154] Table 8

[0155]

[0156] The beneficial effect of the present invention is that, compared with the prior art, the carbon emission flow calculation method proposed in the present invention can accurately calculate the real-time carbon flow distribution of the power system and reasonably divide the carbon emission responsibilities of different entities, which has good practical value for formulating carbon reduction measures and promoting low-carbon development of electricity.

[0157] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, but not to limit the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for real-time acquisition of carbon emission flow in a power system, characterized in that: The method comprises the steps of: (1) Obtain system real-time node load, generator power, network topology and related technical parameters; (2) Use the Newton-Raphson method to calculate the AC power flow equation, obtain the voltage amplitude and angle of each node, and then calculate the active power P of each branch ij and loss (3) Constructing the upstream distribution matrix A u , and then the generator power is apportioned to obtain the generator power component P corresponding to each node load, each branch active power and loss Lk,Gi , P kj,Gi and (4) According to the active power P of the generator set Gi , calculate the real-time carbon emission intensity E of each unit Gi ; (5) Allocate the unit carbon emissions to obtain the generator carbon emission rate component R corresponding to each node load, each branch active power and loss Lk,Gi , R kj,Gi and 2. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In the step (1), the real-time node load of the system is obtained, including active load and reactive load, and the generator power includes active power and reactive power; Relevant technical parameters include the technical parameters and operating status of lines, transformers, and switchgear, the type, capacity, carbon capture rate, carbon content of coal, and coal consumption characteristics per kilowatt-hour of power generation units.

3. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In step (2), the active power and loss of each branch are calculated, that is: P ij =V i V j (G ij cosδ ij +B ij sinδ ij )(3) Where P ij is the active power flowing through branch ij, and its positive direction is from node i to node j; is the active power loss of branch ij.

4. The method for real-time acquisition of carbon emission flow of a power system according to claim 3, characterized in that: In the step (3), A u ∈R n×n is the upstream distribution matrix, and its elements are calculated as follows: In the formula, [A u ] ji Represents the matrix A u The element at row j and column i in .

5. The method for real-time acquisition of carbon emission flow of a power system according to claim 4, characterized in that: In step (3), the power share P drawn by the node k load from the node i generator is Lk,Gi for: The generator connected to node i is kj Contribution share P kj,Gi for: The generator pair connected to node i Contribution share for: In the formula, e i ∈R n×1 is a column vector whose i-th component is 1 and the rest are 0.

6. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In step (3), according to the node power conservation principle, that is, the active power flowing through the node is equal to the total active power flowing into the node, the upstream distribution matrix A is constructed. u ; According to the principle of node power conservation, the active power flowing through the node is equal to the total active power flowing out of the node, and the generated power is allocated to each node load, each branch active power and loss.

7. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In step (4), the carbon emission intensity E of the unit Gi The calculation formula is: In the formula, is the molar mass of carbon dioxide; M C is the molar mass of carbon; η i is the carbon content of the coal burned in unit i; ξ i is the carbon oxidation rate of unit i; μ i is the carbon capture rate.

8. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In the step (5), the carbon emission intensity of the unit is combined with the power distribution of the unit, and the carbon emission of the unit is apportioned according to the power distribution of the power generation to obtain the carbon emission share of the unit required to bear the load of each node, the active power of each branch, and the loss.

9. The method for real-time acquisition of carbon emission flow of a power system according to claim 1, characterized in that: In step (5), the carbon emission rate R of unit i that the node k load needs to bear is Lk,Gi for: R Lk,Gi =P Lk,Gi E Gi (18) The contribution of the generator connected to node i to the carbon emission rate of branch kj is R kj,Gi for: Carbon emission rate contribution of the generator connected to node i to the active power loss of branch kj for:

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