Single-degree-of-freedom active loop-free distribution line transmission efficiency evaluation method and system

Abstract

The invention relates to the technical field of distribution line transmission, in particular to a single-degree-of-freedom active loop-free distribution line transmission efficiency evaluation method and system, and the method comprises the steps: obtaining a certain section of distribution line comprising a bus and a main line, and enabling the two sides of the main line to be provided with a plurality of power supplies and a plurality of loads; determining the overall power flow direction of the distribution line according to the directions of each power supply and each load, obtaining the power from the power supply to each load in the distribution line, and calculating the equivalent load distance of the whole distribution network by arranging the power supplies at different positions in order to meet the electric quantity requirements of all the loads; and finding out the equivalent load distance with the minimum equivalent load distance value, and taking the correspondingly arranged distribution line as a topological structure with the minimum transmission cost. According to the characteristics that the distribution network structure has the optimal network topology power supply mode and the load can evaluate the advantages and disadvantages of different topology power supply, the network topology is evaluated by adopting the equivalent load distance method, and the method has the advantages of comprehensiveness and convenience.

Description

Technical Field

[0001] The present invention relates to the technical field of power distribution line transmission, and in particular to a single-degree-of-freedom active loopless power distribution line transmission efficiency evaluation method and system. Background Art

[0002] The transmission efficiency of distribution network lines is an important indicator of network topology, but the main technical direction is to improve the transmission efficiency, such as the application number CN201310701284.2, which improves the transmission efficiency by adding identifiers at the sending and receiving ends. The parameters used to evaluate the transmission efficiency are currently too complicated and cannot clearly reflect the structural advantages of the network topology, transmission efficiency and network transmission cost.

[0003] The invention patent application with publication number CN116915690A discloses a method and system for evaluating the transmission efficiency of a passive tree-like topology distribution line. The method discloses a characteristic that there is an optimal network topology power supply mode according to the distribution network structure, and the load can evaluate the advantages and disadvantages of different topology power supplies. The equivalent load distance method is used to evaluate the network topology, but the prior art is only used for passive structures. For active situations, no specific solution is given and the scope of use is limited. Summary of the invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method for evaluating the transmission efficiency of the distribution line. On this basis, the present invention also provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation system.

[0005] Technical solution: On the one hand, the present invention provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method, the method comprising the following steps:

[0006] S1 obtains a section of a power distribution line including a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power sources and loads are distributed on both sides of the main line, and the power sources are used to transmit power to the loads;

[0007] S2 confirms the overall power flow direction of the distribution line according to the tree-like line structure and the direction of each power source and load, and determines the length of each power source and load to the main line;

[0008] S3 obtains the power from the power source to each load in the distribution line, and calculates the equivalent load distance of the overall distribution network by arranging the power source and the equivalent at different positions in order to meet the power demand of all loads;

[0009] S4 compares the calculated equivalent load distances, finds the equivalent load distance with the smallest value, and uses the corresponding distribution line as the topological structure with the smallest transmission cost.

[0010] Further, including:

[0011] In step S2, the direction of the power source is defined as the direction pointing to the busbar, and is positive; the direction of the load is defined as the direction away from the busbar, and is negative, thereby obtaining the flow direction of the entire distribution line.

[0012] Further, including:

[0013] According to the principle of directional superposition, the remaining or missing power is obtained based on the power provided by each power source, the power required by the load and the corresponding direction. If the result of vector addition is a negative value, it means that a certain amount of power is missing and electricity is supplied from the bus direction. If the result of vector addition is a positive value, it means that a certain amount of power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power source and load is obtained.

[0014] Further, including:

[0015] In step S3, the equivalent load distance of the overall distribution network caused by arranging power sources and loads at different locations in order to meet the power demand of all loads is calculated, including:

[0016] Starting from any load, if the power required by the current load is L1, first determine whether the power p1 that any power source can provide satisfies p1≥L1. If so, first supply power to the current load and allocate the remaining power p1-L1 to the second load.

[0017] Then, the power L2 required by the second load is compared with the remaining power p1-L1. If p1-L1≥L2 is satisfied,

[0018] After the power of the second load is met, the remaining power p1-L1-L2 is allocated to the third load;

[0019] otherwise,

[0020] If p1<L1, traverse other power sources, select one of them, confirm the power p2 it provides, and confirm whether p1+p2≥L1 is satisfied. If so, power the current load and distribute the remaining power p1+p2-L1 to the second load. Otherwise, continue to traverse other power sources until the current load is powered.

[0021] Repeat the above method to complete the power supply of all loads.

[0022] Further, including:

[0023] After all loads are powered, the corresponding equivalent load distance is calculated, which is specifically expressed as:

[0024]

[0025] Among them, P1 is the power provided by the first power supply, P m is the power provided by the mth power supply, P M is the power provided by the Mth power supply, M is the total number of power supplies, L1 is the power required by the first load, and L n is the power required by the nth load, L N is the power required by the Nth load; T1 is the power provided / required on the first section of the main line, q1 is the length of the first section of the main line, T s The power provided / required on the sth section of main line.

[0026] It is used to characterize the power flow direction of the distribution line; U is the total output value, d1 is the line length corresponding to the power flow from the first power source to the main line, and d m is the line length corresponding to the power flow from the mth power source to the main line, d M is the line length corresponding to the power flow from the Mth power source to the main line, R1 is the line length corresponding to the power flow from the first load to the main line, R n is the line length corresponding to the power flow from the nth load to the main line, R N is the line length corresponding to the power flow from the Nth load to the main line, q s is the length of the sth main line.

[0027] Further, including:

[0028] The total output value U is expressed as:

[0029]

[0030] On the other hand, the present invention also provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation system, the system comprising:

[0031] A line acquisition module is used to acquire a section of a power distribution line including a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power supplies and loads are distributed on both sides of the main line, and the power supply is used to transmit power to the load;

[0032] A direction confirmation module is used to confirm the overall power flow direction of the distribution line according to the above-mentioned tree-like line structure and the direction of each power source and load, and to determine the length of each power source and load to the main line;

[0033] An equivalent load distance calculation module is used to obtain the power from the power source to each load in the distribution line, and calculate the equivalent load distance of different positions of the power source and load arrangement to the overall distribution network in order to meet the power demand of all loads;

[0034] The topology confirmation module is used to compare the calculated equivalent load distances, find the equivalent load distance with the smallest value, and use the corresponding distribution line as the topology with the smallest transmission cost.

[0035] Further, including:

[0036] In the direction confirmation module, the direction of the power supply is defined as the direction pointing to the busbar, and is positive; the direction of the load is defined as the direction away from the busbar, and is negative, thereby obtaining the overall flow direction of the distribution line.

[0037] Further, including:

[0038] According to the principle of directional superposition, the remaining or missing power is obtained based on the power provided by each power source, the power required by the load and the corresponding direction. If the result of vector addition is a negative value, it means that a certain amount of power is missing and electricity is supplied from the bus direction. If the result of vector addition is a positive value, it means that a certain amount of power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power source and load is obtained.

[0039] Beneficial effect: The present invention assumes that the distribution line is active and loopless under single degree of freedom, and uses multiple power supplies to complete power transmission to several loads. Since the power transmission capabilities of the power supplies are different, from the optimization perspective, there should be an optimal network topology power supply method. Therefore, this application adopts the calculation method of equivalent load distance to evaluate the corresponding distribution line, so as to clearly and accurately reflect the structural advantages, transmission efficiency and network transmission cost of the network topology. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a flow chart of a method for evaluating transmission efficiency of a single-degree-of-freedom active loop-free distribution line according to an embodiment of the present invention;

[0041] Figure 2 It is a structural schematic diagram of a certain section of a power distribution line according to an embodiment of the present invention;

[0042] Figure 3 A topological structure formed by the first distribution mode of two power supplies according to an embodiment of the present invention;

[0043] Figure 4 This is a topological structure formed by the second distribution mode of the two power supplies described in the embodiment of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] The load is the demand side of energy, and the distribution line is a specific topological form used to meet the energy demand. For a single-point load, the load distance represents the product of the power and distance from the point to the power source point, and represents the system transmission cost used to meet the energy demand of the point. The load distance in the present invention is not only the distance at the atomic level, but also extends to complex networks. Because a specific distribution line generally needs to meet the energy demand of different characteristics distributed in different locations at the same time, there can be multiple topological structures used to meet the energy demand. Different topological structures correspond to different transmission efficiencies, but the energy demand met is the same. From the perspective of input-output, different topological structures have certain differences in transmission efficiency. If the multi-distributed load points are equivalent to a logical load point, that is, in a certain section of the line, the energy demand required by the actual load is the same as the energy demand required by the corresponding load after equivalent. Therefore, the equivalent load corresponds to different lengths of load distances in the corresponding topological structure, which is similar to the synthesis of torque in principle. Then, similarly, different topological structures also correspond to different lengths of equivalent load distances. Therefore, the equivalent load distance can be used to characterize the transmission efficiency of different topologies.

[0046] Therefore, if Figure 1 As shown, on the one hand, the present invention provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method, the method comprising the following steps:

[0047] S1 obtains a section of a single-degree-of-freedom active loopless distribution line containing a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power supplies and several loads are distributed on both sides of the main line, and the power supplies are used to transmit power to the loads.

[0048] The circuit in the present invention is a constant voltage network and satisfies And U and I are the line voltage and line current, The power factor is a measure of the ratio of the active power consumed by the load to the apparent power. When the load is a pure resistor, the power factor is 1; when the load contains inductance or capacitance, the power factor will be less than 1. Therefore, when U is a constant When the difference is not big, P is proportional to I. Therefore, in calculating the energy loss, the present invention uniformly uses i 2 d is equivalent to p 2d, therefore, for the case of series connection, the equivalent load distance of two loads P1 and P2 can be calculated by the following method, where the arrow direction is the flow direction,

[0049] (i1+i2) 2 d=(i1+i2) 2 d1+i2 2 d2

[0050]

[0051] Specifically, the right side of the first formula is the total energy demand in the actual situation. The current from the power source to P1 is i1+i2, and the current flowing through P2 is i2. Therefore, the total demand on the right side is (i1+i2) 2 d1+i2 2 d2, the corresponding left side is the equivalent state, because the two charges are equivalent to one, and the current flowing through is also (i1+i2). Therefore, the energy demand represented by the left side is expressed as: (i1+i2) 2 d, therefore, the equivalent circuit d is expressed as: Correspondingly, in the present invention, i is replaced by the corresponding power p.

[0052] Therefore, the calculation formula is:

[0053]

[0054] Among them, d1 is the line length between the first load and the power supply, that is, the corresponding load distance, d2 is the line length between the second load and the power supply, that is, the load distance corresponding to the second load, p2 is the power corresponding to the second load, and p1 is the power corresponding to the first load.

[0055] S2 confirms the overall power flow direction of the distribution line according to the above-mentioned tree-like line structure and the direction of each power source and load, and determines the length of each power source and load to the main line.

[0056] Specifically: in step S2, the direction of the power supply is defined as the direction pointing to the bus, and is positive; the direction of the load is defined as the direction away from the bus, and is negative. Therefore, the overall flow direction of the distribution line can be obtained based on the direction of the power supply and the direction of the load.

[0057] That is, in this embodiment, for any tree structure, the tree structure includes a bus and a main line, the power supply and the load are distributed on both sides of the main line, and the main line is directly connected to the bus. Therefore, the length of each power supply or load to the main line can be measured. In order to simplify the calculation, the present invention makes the length of each power supply or load from the main line the same. According to the principle of directional superposition, the remaining or missing power is obtained according to the power provided by each power supply and the power required by the load and the corresponding direction. If the result of the vector addition is a negative value, it means that a certain power is missing and electricity is supplied from the bus direction. If the result of the vector addition is a positive value, it means that a certain power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power supply and load is obtained.

[0058] First, consider the individual role of each element. For example, the power supply includes power supply 1, power supply 2, power supply 3, ..., power supply M. The number of power supplies that can be provided is expressed as: P1, P2, ..., P M , and the loads include load 1, load 2, load 3, ..., load N, and the required number of loads is expressed as: L1, L2, ..., L N In the embodiment of the present invention, the direction of a single power source is the direction pointing to the busbar, which is recorded as positive, and the direction of a single load is away from the busbar, which is recorded as negative. Therefore, the overall flow direction can be determined, and according to the directional superposition operation, the remaining or missing power can also be obtained, that is:

[0059] P1+P2+,...,+P M -L1-L2-,...,-L N If the result is negative, it means a certain amount of electricity is missing, and the power is supplied from the busbar. If the result is positive, it means a certain amount of electricity is remaining, and the power is supplied to the busbar. Based on this, the current passing through each line can be determined.

[0060] S3 obtains the power from the power source to each load in the distribution line, and calculates the equivalent load distance of the overall distribution network when the power source is arranged at different positions in order to meet the power demand of all loads.

[0061] In this embodiment, the equivalent load distance of the overall distribution network caused by arranging power sources and loads at different locations in order to meet the power demand of all loads is calculated, including:

[0062] Starting from any load, if the power required by the current load is L1, first determine whether the power P1 that any power source can provide satisfies P1≥L1. If so, first supply power to the current load and allocate the remaining power P1-L1 to the second load.

[0063] Then, the power L2 required by the second load is compared with the remaining power P1-L1. If P1-L1≥L2 is satisfied, the remaining power P1-L1-L2 is allocated to the third load after the power of the second load is satisfied;

[0064] otherwise,

[0065] If P1<L1, traverse other power sources, select one of them, confirm the power P2 it provides, and confirm whether P1+P2≥L1 is satisfied. If so, supply power to the current load and distribute the remaining power P1+P2-L1 to the second load. Otherwise, continue to traverse other power sources until the current load is powered.

[0066] Repeat the above method to complete the power supply of all loads.

[0067] Further, including:

[0068] After all loads are powered, the corresponding equivalent load distance is calculated, which is specifically expressed as:

[0069]

[0070] That is, the numerator of the above equivalent load distance is the sum of the energy consumed by the power flowing through each segment, and the denominator is the maximum value of the electricity demand or power generation demand that the entire network needs to meet, that is, the total output value.

[0071] Among them, p1 is the power provided by the first power supply, p m is the power provided by the mth power supply, p M is the power provided by the Mth power supply, M is the total number of power supplies, L1 is the power required by the first load, and L n is the power required by the nth load, L N is the power required by the Nth load; T1 is the power provided / required on the first section of the main line, q1 is the length of the first section of the main line, T s The power provided / required on the sth section of main line.

[0072] It is used to characterize the power flow direction of the distribution line; U is the total output value, d1 is the line length corresponding to the power flow from the first power source to the main line, and d m is the line length corresponding to the power flow from the mth power source to the main line, d M is the line length corresponding to the power flow from the Mth power source to the main line, R1 is the line length corresponding to the power flow from the first load to the main line, R n is the line length corresponding to the power flow from the nth load to the main line, R N is the line length corresponding to the power flow from the Nth load to the main line, qs is the length of the sth main line.

[0073] Furthermore, the total output value U in this embodiment is expressed as:

[0074]

[0075] S4 compares the calculated equivalent load distances, finds the equivalent load distance with the smallest value, and uses the corresponding distribution line as the topological structure with the smallest transmission cost.

[0076] As shown in the attached Figure 2 In the distribution line in, it is assumed that there are two power sources in the distribution network, which are respectively recorded as the first power source and the second power source, and the first load and the second load. The power that the first power source can provide is 9, the power that the second power source can provide is 3, the power required by the first load is 6, and the power required by the second load is 1. The bus is connected to the power source and the charge through a line, including a main line. The power source and the charge are distributed on both sides of the main line. Starting from any load, if the power required by load 1 is 6, then after power source 1 provides 6 loads for it, there are 3 remaining, which are transmitted back to the main line, and the charge flow direction flows from the first power source to the load direction. If the second load needs 1 charge, then after the first power source provides 1 charge for it, there are 2 charges remaining, which are transmitted back to the main line. Therefore, the charge received on the main line is 5 and is transmitted back to the bus, that is, h(x)=-1.

[0077] Furthermore, for the sake of simplicity in calculation, in the example of this embodiment, the length of each section of the main line is set to 1, and in the example of this embodiment, the distance between each power source and load and the main line is the same, denoted as d, that is, the length from the power source or load to the main line is also set to 1, and the main line of this application is 4 sections because the main line is divided by the power sources and loads on both sides, and in order to simplify the calculation, the division of this application is equal distance division.

[0078] The corresponding equivalent load distance is expressed as: Among them, U is max{total power output, total load output}, and the power output is (3+9) 2 , the total load demand is (1+6) 2 , therefore, U=144. Figure 3 The calculated equivalent load distance is 1.479.

[0079] If the power of the first power source is 3 and the power of the second power source is 9, according to the above description, the corresponding equivalent load distance can be obtained. Approximately equal to 1.333.

[0080] It should be noted that the examples in this embodiment are just two cases. In actual applications, the number of power sources and loads is not limited to these few, and the layout positions can be anywhere, but the corresponding equivalent load distance can be calculated using the above formula of the present invention.

[0081] Therefore, in order to meet the 12 power demands, the cost paid by the power grid can be obtained according to the above, and the smaller the cost, the better. Therefore, the second power configuration pays a smaller cost, and the corresponding power configuration has a higher transmission efficiency.

[0082] The present invention also provides a single-degree-of-freedom active loopless distribution line transmission efficiency evaluation system, the system comprising:

[0083] A line acquisition module is used to acquire a section of a power distribution line including a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power supplies and loads are distributed on both sides of the main line, and the power supply is used to transmit power to the load;

[0084] A direction confirmation module is used to confirm the overall power flow direction of the distribution line according to the above-mentioned tree-like line structure and the direction of each power source and load, and to determine the length of each power source and load to the main line;

[0085] An equivalent load distance calculation module is used to obtain the power from the power source to each load in the distribution line, and calculate the equivalent load distance of different positions of the power source arrangement to the overall distribution network in order to meet the power demand of all loads;

[0086] The topology confirmation module is used to compare the calculated equivalent load distances, find the equivalent load distance with the smallest value, and use the corresponding distribution line as the topology with the smallest transmission cost.

[0087] Further, including:

[0088] In the direction confirmation module, the direction of the power supply is defined as the direction pointing to the busbar, and is positive; the direction of the load is defined as the direction away from the busbar, and is negative, thereby obtaining the overall flow direction of the distribution line.

[0089] Further, including:

[0090] According to the principle of directional superposition, the remaining or missing power is obtained based on the power provided by each power source, the power required by the load and the corresponding direction. If the result of vector addition is a negative value, it means that a certain amount of power is missing and electricity is supplied from the bus direction. If the result of vector addition is a positive value, it means that a certain amount of power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power source and load is obtained.

[0091] Other technical features of the evaluation system described in the present invention are the same as those of the corresponding single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method, and the present invention will not be repeated here.

[0092] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0093] Obviously, those skilled in the art can make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the embodiments of the present invention. Thus, if these modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method, characterized in that: The method comprises the following steps: S1 obtains a distribution line of a certain tree-like line structure, which is a distribution line containing at least a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power sources and loads are distributed on both sides of the main line, wherein the power source is used to transmit power to the load; S2 confirms the overall power flow direction of the distribution line according to the tree-like line structure and the direction of each power source and load, and determines the length of each power source and load to the main line; S3 obtains the power from the power source to each load in the distribution line, and calculates the equivalent load distance of the overall distribution network when the power source and the load are arranged at different positions in order to meet the power demand of all loads; S4 compares the calculated equivalent load distances, finds the equivalent load distance with the smallest value, and uses the corresponding distribution line as the topological structure with the smallest transmission cost.

2. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method according to claim 1 is characterized in that: In step S2, the direction of the power source is defined as the direction pointing to the busbar, and is positive; the direction of the load is defined as the direction away from the busbar, and is negative, thereby obtaining the flow direction of the entire distribution line.

3. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method according to claim 2 is characterized in that: According to the principle of directional superposition, the remaining or missing power is obtained based on the power provided by each power source, the power required by the load and the corresponding direction. If the result of vector addition is a negative value, it means that a certain amount of power is missing and electricity is supplied from the bus direction. If the result of vector addition is a positive value, it means that a certain amount of power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power source and load is obtained.

4. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method according to claim 3 is characterized in that: In step S3, the equivalent load distance of the overall distribution network caused by arranging power sources at different locations in order to meet the power demand of all loads is calculated, including: Starting from any load, if the power required by the current load is L1, first determine whether the power p1 that any power source can provide satisfies p1≥L1. If so, first supply power to the current load and allocate the remaining power p1-L1 to the second load. Then, the power L2 required by the second load is compared with the remaining power p1-L1. If p1-L1≥L2, After the power of the second load is met, the remaining power p1-L1-L2 is allocated to the third load; otherwise, If p1<L1, traverse other power sources, select one of them, confirm the power p2 it provides, and confirm whether p1+p2≥L1 is satisfied. If so, power the current load and distribute the remaining power p1+p2-L1 to the second load. Otherwise, continue to traverse other power sources until the current load is powered. Repeat the above method to complete the power supply of all loads.

5. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method according to claim 4 is characterized in that: After all loads are powered, the corresponding equivalent load distance is calculated, which is specifically expressed as: Among them, P1 is the power provided by the first power supply, P m is the power provided by the mth power supply, P M is the power provided by the Mth power supply, M is the total number of power supplies, L1 is the power required by the first load, and L n is the power required by the nth load, L N is the power required by the Nth load; T1 is the power provided / required on the first section of the main line, q1 is the length of the first section of the main line, T s The power provided / required for the main line of section s; It is used to characterize the power flow direction of the distribution line; U is the total output value, d1 is the line length corresponding to the power flow from the first power source to the main line, and d m is the line length corresponding to the power flow from the current of the mth power source to the main line, d M is the line length corresponding to the power flow from the Mth power source to the main line, R1 is the line length corresponding to the power flow from the first load to the main line, R n is the line length corresponding to the power flow from the nth load to the main line, R N is the line length corresponding to the power flow from the Nth load to the main line, q s is the length of the sth main line.

6. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation method according to claim 5 is characterized in that: The total output value U is expressed as:

7. A single-degree-of-freedom active loopless distribution line transmission efficiency evaluation system, characterized in that: The system comprises: A line acquisition module is used to acquire a section of a power distribution line including a busbar and a main line, wherein the main line is directly connected to the busbar, and multiple power supplies and loads are distributed on both sides of the main line, and the power supply is used to transmit power to the load; A direction confirmation module is used to confirm the overall power flow direction of the distribution line according to the above-mentioned tree-like line structure and the direction of each power source and load, and to determine the length of each power source and load to the main line; An equivalent load distance calculation module is used to obtain the power from the power source to each load in the distribution line, and calculate the equivalent load distance of different positions of the power source and load arrangement to the overall distribution network in order to meet the power demand of all loads; The topology confirmation module is used to compare the calculated equivalent load distances, find the equivalent load distance with the smallest value, and use the corresponding distribution line as the topology with the smallest transmission cost.

8. The single-degree-of-freedom active loopless distribution line transmission efficiency evaluation system according to claim 7, characterized in that: In the direction confirmation module, the direction of the power supply is defined as the direction pointing to the busbar, and is positive; the direction of the load is defined as the direction away from the busbar, and is negative, thereby obtaining the overall flow direction of the distribution line.

9. The single-degree-of-freedom active loop-free distribution line transmission efficiency evaluation system according to claim 8, characterized in that: According to the principle of directional superposition, the remaining or missing power is obtained based on the power provided by each power source, the power required by the load and the corresponding direction. If the result of vector addition is a negative value, it means that a certain amount of power is missing and electricity is supplied from the bus direction. If the result of vector addition is a positive value, it means that a certain amount of power is remaining and electricity is supplied to the bus direction. Therefore, the corresponding current passing through each power source and load is obtained.

10. The single-degree-of-freedom active loop-free distribution line transmission efficiency evaluation system according to claim 9, characterized in that: In the equivalent load distance calculation module, the equivalent load distance of the overall distribution network caused by arranging power sources and loads at different locations in order to meet the power demand of all loads is calculated, including: Starting from any load, if the power required by the current load is L1, first determine whether the power p1 that any power source can provide satisfies p1≥L1. If so, first supply power to the current load and allocate the remaining power p1-L1 to the second load. Then, the power L2 required by the second load is compared with the remaining power p1-L1. If p1-L1≥L2, After the power of the second load is met, the remaining power p1-L1-L2 is allocated to the third load; otherwise, If p1<L1, traverse other power sources, select one of them, confirm the power p2 it provides, and confirm whether p1+p2≥L1 is satisfied. If so, power the current load and distribute the remaining power p1+p2-L1 to the second load. Otherwise, continue to traverse other power sources until the current load is powered. Repeat the above method to complete the power supply of all loads.

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