A method for accurately obtaining carbon emission flow taking into account transmission line loss correction

Abstract

A method for accurately obtaining carbon emission flow taking into account the correction of transmission line loss, comprising the following steps: step 1: correcting the transmission line loss; step 2: performing lossless network conversion of the corrected transmission line loss; step 3: converting the obtained line loss correction of each line into the line node load; step 4: obtaining the carbon emission flow corrected for the transmission line loss. The purpose of the present invention is to solve the technical problem that there is a certain difference between the carbon flow rate on the power generation side and the carbon flow rate on the load side obtained by the existing carbon flow calculation method, which affects the carbon emission monitoring effect of the power grid, and to provide a method for accurately obtaining carbon emission flow taking into account the correction of transmission line loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular to the fields of accurate carbon emission accounting, carbon reduction and carbon mitigation, and specifically to a method for accurately calculating carbon emission flows taking into account transmission line loss correction. Background Art

[0002] According to the existing carbon flow acquisition method, the calculated carbon flow rate on the power generation side should be equal to the carbon flow rate on the load side. However, in practice, there is a certain difference between the carbon flow rate on the power generation side and the carbon flow rate on the load side calculated by the existing carbon flow calculation method. This results in the actual situation being different from the theoretical calculation results, which increases the difficulty of studying issues such as line loss carbon rate allocation.

[0003] The patent document with the authorization announcement number CN115907307A discloses an online analysis method for carbon emission flow of power system for real-time data interaction of power grid. Based on the carbon emission flow calculation method, the real-time data in the power grid is analyzed and calculated to obtain the real-time carbon emission flow of the power system. Although the above method can obtain the real-time carbon emission flow of the power system, the line loss carbon rate calculated by it still has a certain error with the actual line loss carbon flow.

[0004] When calculating the line loss carbon rate, not only the theoretical line loss carbon rate is included, but also the actual line carbon rate caused by factors such as temperature compensation loss and corona loss.

[0005] Therefore, the applicant proposes a method for accurately calculating and obtaining carbon emission flow taking into account transmission line loss correction. Summary of the invention

[0006] The purpose of the present invention is to solve the technical problem that there is a certain difference between the carbon flow rate on the power generation side and the carbon flow rate on the load side obtained by the existing carbon flow calculation method, which will affect the carbon emission monitoring effect of the power grid, and to provide a method for accurately obtaining the carbon emission flow taking into account the transmission line loss correction.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A method for accurately obtaining carbon emission flow taking into account transmission line loss correction includes the following steps:

[0009] Step 1: Correction of transmission line losses;

[0010] Step 2: Perform lossless network transformation to correct for transmission line losses;

[0011] Step 3: The obtained line loss correction amount of each line is equivalent to the line non-node load;

[0012] Step 4: Obtain the carbon emission flow corrected for transmission line losses.

[0013] In step 1, the correction includes overhead line temperature compensation, corona loss compensation and overhead ground wire power loss compensation;

[0014] Step 1.1: Calculate the overhead line temperature compensation:

[0015] ΔS′ L =k w ×ΔS L (1)

[0016] In the formula, ΔS L is the line loss before temperature compensation; ΔS′ L k is the line loss after temperature compensation based on power flow calculation; w is the temperature rise coefficient;

[0017] Step 1.2: Calculate overhead line corona losses

[0018] The calculation method of corona loss is shown in formula (2).

[0019]

[0020] In the formula, is the line loss after taking into account corona loss.

[0021] Step 1.3: Calculate the overhead ground wire power loss as follows:

[0022] (1) Double overhead ground wire

[0023] The loss ΔS caused by the induced current between the two ground wires H Calculated by formula (3).

[0024]

[0025] Where, L is the length of the overhead ground wire; d 1A d 1C and d 12 are the distances between overhead ground wire, conductor and two-phase line respectively; T is the line loss calculation period; I jf is the RMS current during the line loss calculation period; R i is the overhead ground wire resistance at 20℃; r is the overhead ground wire radius; x i It is the unit inductive reactance of double overhead ground wire;

[0026] The loss ΔS caused by the induced current between the ground wire and the earth D

[0027]

[0028] Where, f is the current frequency; D0 is the equivalent depth of the induced current;

[0029] So there are double overhead ground wires, and both sides have full grounding losses.

[0030] ΔS2=ΔS H +ΔS D (5)

[0031] (2) Single overhead ground wire

[0032] Energy consumption of single overhead ground wire (or energy consumption of single-side grounding of double overhead ground wires) ΔS1

[0033]

[0034] Where S1 is the complex induced electromotive force.

[0035] In step 2, the network loss obtained from the power flow calculation needs to be allocated to the load side.

[0036] For any node in the grid, obtain the inflow power S of node i i As shown below:

[0037]

[0038] In the formula, i - is the set of downstream nodes of node i; S ij is the power flowing out of node i on line ij; S Li is the load on node i. If node i has no load, the variable is 0.

[0039] Since the present invention adopts the reverse current tracking method to solve the network loss caused by each generator injecting power into the grid, S in the above formula can be ij becomes the power injected into node j |S ji | and the network loss S on line ij ij,loss The sum of , then formula (7) can be transformed into:

[0040]

[0041] In the formula, S i-,loss is the sum of the network losses of all downstream node branches connected to node i. Reducing the same type of phase, the above formula can be rewritten as:

[0042]

[0043] Convert the above formula into matrix form, which can be expressed as:

[0044] A d S=S L +S Σ-,loss (10)

[0045] In the formula, S Σ-,lossis the network loss set on the branch composed of the downstream nodes of all nodes in the grid; S is the vector composed of the injected power of all nodes in the grid; S L is the node load power vector; A d is the downstream distribution matrix, whose elements are shown as follows:

[0046]

[0047] Assume that the injected power on the generator bus i in the network is S Gi , the parameter can be rewritten as shown below:

[0048]

[0049] In the formula, e i T ∈R n , is a column vector with the i-th variable being 1 and the rest being 0, where n represents the number of nodes in the grid. From formula (12), we can see that the grid loss caused by generator node i is S Gi,loss :

[0050]

[0051] Therefore, the output S′ of each generator after conversion into a lossless network is Gi It can be calculated by formula (14):

[0052] S′ Gi =S Gi -S Gi,loss (14)

[0053] In summary, the network can be transformed into a basically lossless network.

[0054] In order not to increase the calculation dimension and reduce the number of nodes in the grid, this method equates the calculated correction of the transmission line loss to the load at the end node of the line, such as Figure 1 As shown, a lossless network taking into account the corrected line loss can be obtained.

[0055] In step 3,

[0056] Step 3.1: Determine the flow direction of each line as follows:

[0057] t bus =[t1,t2,t3,…,t i ,…,t nl ] (15)

[0058] Among them, t bus The number vector of the node where the line power flow is injected; n l is the number of lines; t iThe number of the power flow injection node on the i-th line.

[0059] Step 3.2: Equivalently convert the line loss correction calculated in step 1 to t bus The node load at .

[0060] In step 4, when obtaining the carbon emission flow corrected for transmission line losses;

[0061] Step 4.1: First, the DC power flow distribution matrix, unit injection distribution matrix and generator unit carbon emission intensity vector are calculated through the power flow results. B is the DC power flow distribution matrix of the network, and (n l is the number of branches in the grid); P G Inject the distribution matrix into the network's units, and (n g is the number of generators in the grid, n b is the number of nodes in the grid); E G is the carbon emission intensity of the network’s generators, and

[0062] Step 4.2: Based on the above variables, let P Z =[P B P G ] T Then the active flux P can be obtained N for:

[0063]

[0064] In the formula, n b +n g A row vector of order , where all elements are 1.

[0065] Step 4.3: Calculate the node carbon potential E of the network N And the branch carbon flow rate distribution matrix R B :

[0066]

[0067] In summary, the carbon emission flow that takes into account the correction of transmission line losses can be obtained.

[0068] Compared with the prior art, the present invention has the following technical effects:

[0069] The present invention proposes a method for accurately obtaining carbon emission flows that takes into account transmission line loss correction. The method can accurately calculate the actual line loss of each line in the grid, and convert the network into a lossless network through the power flow tracking method. The line loss correction value of each transmission line is then equivalent to the load. Finally, the carbon emission rate of each node in the actual operation of the power grid is calculated through the carbon emission flow, which lays the foundation for the accurate calculation of the carbon emission flow of the regional power grid and can ensure the actual carbon emission rate of each node in the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0071] Figure 1 is a flow chart of the present invention;

[0072] Figure 2 Schematic diagram of a lossless network taking into account the corrected line loss in the present invention. DETAILED DESCRIPTION

[0073] A method for accurately obtaining carbon emission flow taking into account transmission line loss correction includes the following steps:

[0074] Step 1: Correction of transmission line losses;

[0075] Step 2: Perform lossless network transformation to correct for transmission line losses;

[0076] Step 3: Equivalent the obtained line loss correction amount of each line to the line non-node load; Step 4: Obtain the carbon emission flow corrected by the transmission line loss.

[0077] In step 1, the correction includes overhead line temperature compensation, corona loss compensation and overhead ground wire power loss compensation;

[0078] Step 1.1: Calculate the overhead line temperature compensation:

[0079] ΔS′ L =k w ×ΔS L (1)

[0080] In the formula, ΔS L is the line loss before temperature compensation; ΔS′ L k is the line loss after temperature compensation based on power flow calculation; w is the temperature rise coefficient;

[0081] Step 1.2: Calculate overhead line corona losses

[0082] The calculation method of corona loss is shown in formula (2).

[0083]

[0084] In the formula, is the line loss after taking into account corona loss.

[0085] Step 1.3: Calculate the overhead ground wire power loss as follows:

[0086] (1) Double overhead ground wire

[0087] The loss ΔS caused by the induced current between the two ground wires H Calculated by formula (3).

[0088]

[0089] Where, L is the length of the overhead ground wire; d 1A d 1C and d 12 are the distances between overhead ground wire, conductor and two-phase line respectively; T is the line loss calculation period; I jf is the RMS current during the line loss calculation period; R i is the overhead ground wire resistance at 20℃; r is the overhead ground wire radius; x i It is the unit inductive reactance of double overhead ground wire;

[0090] The loss ΔS caused by the induced current between the ground wire and the earth D

[0091]

[0092] Where, f is the current frequency; D0 is the equivalent depth of the induced current;

[0093] So there are double overhead ground wires, and both sides have full grounding losses.

[0094] ΔS2=ΔS H +ΔS D (5)

[0095] (2) Single overhead ground wire

[0096] Energy consumption of single overhead ground wire (or energy consumption of single-side grounding of double overhead ground wires) ΔS1

[0097]

[0098] Where S1 is the complex induced electromotive force.

[0099] In step 2, the network loss obtained from the power flow calculation needs to be allocated to the load side.

[0100] For any node in the grid, obtain the inflow power S of node i i As shown below:

[0101]

[0102] In the formula, i - is the set of downstream nodes of node i; S ij is the power flowing out of node i on line ij; S Li is the load on node i. If node i has no load, the variable is 0.

[0103] Since the present invention adopts the reverse current tracking method to solve the network loss caused by each generator injecting power into the grid, S in the above formula can be ij becomes the power injected into node j |S ji | and the network loss S on line ij ij,loss The sum of , then formula (7) can be transformed into:

[0104]

[0105] In the formula, S i-,loss is the sum of the network losses of all downstream node branches connected to node i. Reducing the same type of phase, the above formula can be rewritten as:

[0106]

[0107] Convert the above formula into matrix form, which can be expressed as:

[0108] A d S=S L +S Σ-,loss (10)

[0109] In the formula, S Σ-,loss is the network loss set on the branch composed of the downstream nodes of all nodes in the grid; S is the vector composed of the injected power of all nodes in the grid; S L is the node load power vector; A d is the downstream distribution matrix, whose elements are shown as follows:

[0110]

[0111] Assume that the injected power on the generator bus i in the network is S Gi , the parameter can be rewritten as shown below:

[0112]

[0113] In the formula, is a column vector with the i-th variable being 1 and the rest being 0, where n represents the number of nodes in the grid. From formula (12), we can see that the grid loss caused by generator node i is S Gi,loss :

[0114]

[0115] Therefore, the output S′ of each generator after conversion into a lossless network is Gi It can be calculated by formula (14):

[0116] S′ Gi =S Gi -S Gi,loss (14)

[0117] In summary, the network can be transformed into a basically lossless network.

[0118] In order not to increase the calculation dimension and reduce the number of nodes in the grid, this method equates the calculated correction of the transmission line loss to the load at the end node of the line, such as Figure 1 As shown, a lossless network taking into account the corrected line loss can be obtained.

[0119] In step 3:

[0120] Step 3.1: Determine the flow direction of each line as follows:

[0121] t bus =[t1,t2,t3,…,t i ,…,t nl ] (15)

[0122] Among them, t bus The number vector of the node where the line power flow is injected; n l is the number of lines; t i The number of the power flow injection node on the i-th line.

[0123] Step 3.2: Equivalently convert the line loss correction calculated in step 1 to t bus The node load at .

[0124] In step 4, when obtaining the carbon emission flow corrected for transmission line losses;

[0125] Step 4.1: First, the DC power flow distribution matrix, unit injection distribution matrix and generator unit carbon emission intensity vector are calculated through the power flow results. B is the DC power flow distribution matrix of the network, and (n l is the number of branches in the grid); P G Inject the distribution matrix into the network's units, and (n g is the number of generators in the grid, n b is the number of nodes in the grid); E G is the carbon emission intensity of the network’s generators, and

[0126] Step 4.2: Based on the above variables, let P Z =[P B P G ] T Then the active flux P can be obtained N for:

[0127]

[0128] In the formula, n b +n g A row vector of order , where all elements are 1.

[0129] Step 4.3: Calculate the node carbon potential E of the network N And the branch carbon flow rate distribution matrix R B :

[0130]

[0131] In summary, the carbon emission flow that takes into account the correction of transmission line losses can be obtained.

Claims

1. A method for accurately obtaining carbon emission flow taking into account transmission line loss correction, characterized in that: It includes the following steps: Step 1: Correction of transmission line losses; Step 2: Perform lossless network transformation to correct for transmission line losses; Step 3: The obtained line loss correction value of each line is equivalent to the line end node load; Step 4: Obtain the carbon emission flow corrected for transmission line losses; In step 4, when obtaining the carbon emission flow corrected for transmission line losses; Step 4.1: First, the DC power flow distribution matrix, unit injection distribution matrix and generator unit carbon emission intensity vector are calculated through the power flow results; where P B is the DC power flow distribution matrix of the network, and n l is the number of branches in the grid; P G Inject the distribution matrix into the network's units, and n g is the number of generators in the grid, n b is the number of nodes in the grid; E G is the carbon emission intensity of the network’s generators, and Step 4.2: Based on the above variables, let P Z =[P B P G ] T Then the active flux P is obtained N for: In the formula, n b +n g A row vector of order , with all elements being 1; Step 4.3: Calculate the node carbon potential E of the network N And the branch carbon flow rate distribution matrix R B : In summary, the carbon emission flow taking into account the correction of transmission line losses is obtained; In step 1, the correction includes overhead line temperature compensation, corona loss compensation and overhead ground wire power loss compensation; Step 1.1: Calculate the overhead line temperature compensation: △S′ L =k w ×△S L (1) In the formula, △S L is the line loss before temperature compensation; △S′ L k is the line loss after temperature compensation based on power flow calculation; w is the temperature rise coefficient; Step 1.2: Calculate overhead line corona losses The calculation method of corona loss is shown in formula (2); In the formula, This is the line loss after taking into account the corona loss; Step 1.3: Calculate the overhead ground wire power loss as follows: (1) Double overhead ground wire The loss △S caused by the induced current between the two ground wires H Calculated by formula (3); Where, L is the length of the overhead ground wire; d 1A ,d 1C and d 12 are the distances between overhead ground wire, conductor and two-phase line respectively; T is the line loss calculation period; I jf is the RMS current during the line loss calculation period; R i is the overhead ground wire resistance at 20℃; r is the overhead ground wire radius; x i It is the unit inductive reactance of double overhead ground wire; The loss △S caused by the induced current between the ground wire and the earth D Where, f is the current frequency; D0 is the equivalent depth of the induced current; So the double overhead ground wire, the full grounding loss on both sides is: △S2=△S H +△S D (5)(2) Single overhead ground wire Energy consumption of single overhead ground wire or single-side grounding energy consumption of double overhead ground wires ΔS1 In the formula, S1 is the complex induced electromotive force; In step 2, the network loss obtained by power flow calculation is allocated to the load side; For any node in the grid, obtain the inflow power S of node i i As shown below: In the formula, i - is the set of downstream nodes of node i; S ij is the power flowing out of node i on line ij; S Li is the load on node i. If node i has no load, the variable is 0; The reverse current tracking method is used to solve the network loss caused by each generator injecting power into the grid. ij becomes the power injected into node j |S ji | and the network loss S on line ij ij,loss The sum of , then formula (7) is transformed into: In the formula, is the sum of the network losses of all downstream node branches connected to node i; if the same type is reduced, the above formula can be rewritten as: Convert the above formula into matrix form, which is expressed as: In the formula, is the network loss set on the branch composed of the downstream nodes of all nodes in the grid; S is the vector composed of the injected power of all nodes in the grid; S L is the node load power vector; A d is the downstream distribution matrix, whose elements are shown as follows: Assume that the injected power on the generator bus i in the network is S Gi , then rewrite the parameter as follows: In the formula, is a column vector with the i-th variable being 1 and the rest being 0, where n represents the number of nodes in the grid. From equation (12), the grid loss caused by the generator node i is S Gi,loss : Therefore, the output S′ of each generator after conversion into a lossless network is Gi Calculated by formula (14): S′ Gi =S Gi -S Gi,loss (14) In summary, the network is transformed into a basically lossless network; In order not to increase the calculation dimension and reduce the number of nodes in the grid, the calculated correction amount of the transmission line loss is equivalent to the load at the end node of the line, that is, a lossless network taking into account the corrected line loss is obtained.

2. The method according to claim 1, characterized in that In step 3, Step 3.1: Determine the flow direction of each line as follows: t bus =[t1,t2,t3,…,t i ,…,t nl ] (15) Among them, t bus The number vector of the node where the line power flow is injected; n l is the number of lines; t i is the number of the power flow injection node on the i-th line; Step 3.2: Equivalently convert the line loss correction calculated in step 1 to t bus The node load at .

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