A new windmill-shaped distribution network wiring structure and load transfer method

Abstract

The present invention discloses a novel windmill-shaped distribution network wiring structure and load transfer method, which are applied to a power supply area including at least two substations; wherein the distribution network wiring structure is: the outgoing line of each substation is evenly divided into two sections according to the distribution capacity or actual load data through a connecting ring network cabinet; the connecting ring network cabinet on each outgoing line is connected to the end of another interconnected outgoing line by a normally open switch, so that the outgoing lines of each substation are nested and connected to each other, forming an N-petal windmill-like structure, where N is the number of substations. The present invention improves the line carrying capacity and operation flexibility, reduces the cost of network construction, and the networking logic and the action logic of the distribution automation after the line failure are simple, the networking is standardized, and will not cause the problem of complex interconnection line relationship and difficult structure analysis caused by the multi-connection wiring method.

Description

Technical Field

[0001] The present invention relates to the technical field of power system distribution network, and in particular to a novel windmill-shaped distribution network wiring structure and a load transfer method. Background Art

[0002] With the construction of new power systems, while higher and higher requirements are being placed on power supply capacity, power supply reliability, network self-healing capabilities, etc., higher adaptability requirements are also being placed on distribution networks to adapt to the discrete and random access of distributed power sources.

[0003] At present, the wiring modes of 10kV / 20kV distribution networks in China are mainly single-link, single-ring, double-ring, multi-segment moderate liaison and other typical power supply modes. Among them, single-link and single-ring networks have the advantages of simple grid structure, clear power supply range, and simple distribution automation action logic configuration. They are the main network construction modes recommended in the State Grid Distribution Network Planning Technical Guidelines. However, under the premise of meeting the reliability of power supply, they have the disadvantages of low average single line load (average load rate cannot exceed 50%), large line corridor occupancy, poor flexibility in operation mode adjustment, and poor adaptability to distributed power access. The double-ring network has a large demand for line corridors, requires the construction of more channels with the same path, and affects the power supply reliability when the capacity of a single large user is too large. If the number and mode of liaison are not controlled for multi-segment moderate liaison, it may lead to a complex grid structure, chaos in the power supply area, and complex load transfer and distribution automation configuration schemes. In particular, after large-scale access to distributed power sources in the future, the flow of double-ring networks and multi-link lines will become complex and difficult to analyze and control. Summary of the invention

[0004] In view of the deficiencies in the above-mentioned prior art, the purpose of the present invention is to provide a new windmill-shaped distribution network wiring structure and load transfer method to improve the average load rate of the line. At the same time, the interconnection logic is unified and the rules are simple, avoiding the problem of complex grid structure caused by multiple interconnection lines and difficult analysis and control.

[0005] In a first aspect, a novel windmill-shaped power distribution network connection structure is provided, which is applied to a power supply area including at least two substations;

[0006] The outgoing line of each substation is evenly divided into two sections according to the distribution transformer capacity or actual load data through a contact ring main unit;

[0007] The interconnecting ring main unit on each outgoing line is connected to the end of another interconnected outgoing line using a normally open switch, so that the outgoing lines of each substation are nested and connected with each other, forming an N-petal windmill-like structure, where N is the number of substations.

[0008] Furthermore, each combined ring main unit has three incoming switches, including a normally open switch and two normally closed switches; the lines connected to the two normally closed switches are the middle sections of the trunk lines of the corresponding outgoing lines, and the lines connected to the normally open switches are the ends of another interconnected outgoing line.

[0009] Furthermore, when the number of outgoing lines of all substations is not equal, windmill-like structures with different numbers of petals are mixed.

[0010] Furthermore, the number of outgoing lines of N substations is A 1 , A 2 , …A N-2 , A N-1 , A N , and A 1 ≤A 2 ≤…≤A N-2 ≤A N-1 ≤A N When A 1 A pinwheel-like structure with N petals. 2 - A 1 The pinwheel-like structure of group N-1 petals, A N-1 - A N-2 A 2-petal windmill structure, the remaining A N - A N-1 The outgoing lines form a single ring network or a single radiation in the traditional networking mode.

[0011] Furthermore, the number of substations in the power supply area is at least three.

[0012] In a second aspect, a load transfer method based on the aforementioned novel windmill-shaped distribution network connection structure is provided, comprising the following steps:

[0013] Assume that an outgoing line is divided into two sections by the interconnection ring main unit, the section close to the substation is the front section of the line, and the other section is the rear section of the line;

[0014] When the fault point is located within the front section of an outgoing line, the line section from the fault point to the interconnecting ring network cabinet in the middle of the current outgoing line is transferred to the rear section of the line of the corresponding interconnected outgoing line, and the rear section of the line of the current outgoing line is transferred to the front section of the line of the corresponding interconnected outgoing line; when the fault point is located within the rear section of an outgoing line, the line end from the fault point to the current outgoing line is transferred to the front section of the line of the corresponding interconnected outgoing line.

[0015] Furthermore, when the fault point is located within the front section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; then disconnect the connection between the connecting ring main unit in the middle of the current outgoing line and the rear section of the line to isolate the front section of the line from the rear section of the line; close the normally open switch of the connecting ring main unit in the middle of the current outgoing line to connect the front section of the line of the current outgoing line with the rear section of the line of the corresponding interconnected outgoing line; close the normally open switch of the connecting ring main unit connected to the end of the current outgoing line to connect the rear section of the line of the current outgoing line with the front section of the line of the corresponding interconnected outgoing line;

[0016] When the fault point is located within the rear section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; close the normally open switch of the interconnecting ring network cabinet connected to the end of the current outgoing line to connect the rear section of the current outgoing line with the front section of the corresponding interconnected outgoing line.

[0017] The present invention proposes a novel windmill-shaped distribution network connection structure and load transfer method, which has the following beneficial effects:

[0018] 1. High line carrying capacity and operation flexibility: Since each line is divided into two sections, each section is backed up by other lines, and each line only needs to reserve half of the load power supply margin of the interconnected lines, the average load rate in each wiring group only needs to be controlled at 66% to ensure power supply reliability; at the same time, the higher load rate operating range can better adapt to the random development of distributed power sources.

[0019] 2. Low network construction cost: Since the average maximum load rate is increased from 50% to 66%, the number of lines required in the area can be reduced at the planning level, and the demand for line channels can be reduced. Through the use of multiple types of mutual nesting, it can adapt to the development and changes of surrounding substations and substation outgoing line intervals. The distribution network wiring structure designed by the present invention will not cause problems such as line main and branch line changes, line diversion, and demolition during the development and construction of the power grid, thereby reducing the construction cost during the transition of the grid construction.

[0020] 3. The networking logic and the action logic of distribution automation after line failure are simple and the networking is standardized, which will not lead to the problem of complex interconnection line relationships and difficult structural analysis caused by multi-connection wiring methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of a wiring structure of a new windmill-shaped distribution network including two substations provided by an embodiment of the present invention;

[0023] Figure 2 It is a schematic diagram of the wiring structure of a new windmill-shaped distribution network including three substations provided by an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the wiring structure of a new windmill-shaped distribution network including four substations provided by an embodiment of the present invention;

[0025] Figure 4 It is a schematic diagram of the wiring structure of a new windmill-shaped distribution network in a situation of multiple transformer substations and multiple outgoing lines provided by an embodiment of the present invention;

[0026] Figure 5 It is a schematic diagram of the load transfer principle of a new windmill-shaped distribution network connection structure including four substations provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0028] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. In the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or order. In addition, in the description of the present invention, unless otherwise specified, the meaning of "plurality" refers to at least two.

[0029] The present invention proposes a novel windmill-shaped distribution network connection structure and load transfer method. By interconnecting multiple lines, the proportion of load that needs to be transferred after a line failure is reduced, and the average load rate of the line is increased (average load rate 66%). At the same time, the interconnection logic is unified and the rules are simple, avoiding the complex grid structure caused by multiple interconnection lines and the problem that the tidal current is difficult to analyze. After any section of the line fails, the power grid can be continuously powered by a load transfer. The action logic is simple and can adapt to various possible upper-level substation layouts during the development and construction of the power grid. The technical solution of the present invention is described in detail below in conjunction with specific embodiments.

[0030] like Figures 1 to 3As shown, the embodiment of the present invention proposes a novel windmill-shaped power distribution network connection structure, which is applied to a power supply area including at least two substations 1;

[0031] The outgoing line of each substation is evenly divided into two sections according to the distribution transformer capacity or actual load data through a contact ring main unit 2;

[0032] The interconnecting ring main unit 2 on each outgoing line is connected to the end of another interconnected outgoing line by using a normally open switch, so that the outgoing lines of each substation 1 are nested and connected with each other, forming an N-petal windmill-like structure, where N is the number of substations 1; there are as many substations 1 in the vicinity as there are blades of the windmill-like structure.

[0033] Specifically, each combined ring main unit 2 has three incoming switches, including a normally open switch and two normally closed switches; the lines connected to the two normally closed switches are the middle sections of the trunk lines of the corresponding outgoing lines, and the lines connected to the normally open switches are the ends of another interconnected outgoing line.

[0034] In specific implementation, the new windmill-shaped distribution network connection structure has various forms according to the number of substations 1 in the power supply area. Figure 1 As shown in the figure, the power supply area includes two substations 1, forming a two-petal windmill-like structure. When the number of substations 1 in the power supply area increases to three, the new windmill-shaped distribution network connection structure can be Figure 2 The structure shown in the figure, without dismantling and renovating the old line, the new line meets the load growth and networking needs of the power supply area. When the number of substations 1 in the power supply area continues to increase to four, it can continue to follow Figure 3 In the structure shown, without dismantling and renovating the old line, the new line can meet the load growth and networking requirements of the power supply area. And so on.

[0035] Of course, in actual applications, there are multiple substations in a power supply area, and each substation may have more than one outgoing line. Therefore, in one or more embodiments, it is proposed that when the number of outgoing lines of all substations is not equal, windmill-like structures with different numbers of petals are used for mixing.

[0036] Specifically, assume that the number of outgoing lines of N substations in the power supply area is A 1 , A 2 , …A N-2 , A N-1 , A N , and A 1 ≤A 2 ≤…≤A N-2 ≤A N-1 ≤A N When A 1 A pinwheel-like structure with N petals. 2 - A1 The pinwheel-like structure of group N-1 petals, A N-1 - A N-2 A 2-petal windmill structure, the remaining A N - A N-1 The outgoing lines form a single ring network or a single radiation in the traditional networking mode.

[0037] like Figure 4 As shown, a mixed situation including four substations is shown. The number of outgoing lines of the four substations a, b, c, and d are 1, 2, 3, and 3 respectively; then a group of four-petal windmill-like structures, a group of three-petal windmill-like structures, and a group of two-petal windmill-like structures can be formed.

[0038] Based on the novel windmill-shaped distribution network connection structure proposed in the above-mentioned embodiment, the embodiment of the present invention further proposes a load transfer method, which is used for performing fault isolation and load transfer in the distribution automation after a line fault occurs in the novel windmill-shaped distribution network connection structure. The action logic can be simply described as "the faulty rear section transfers to the adjacent front section, and the faulty front section transfers to the adjacent rear section". Specifically, the load transfer method includes the following steps:

[0039] Assume that an outgoing line is divided into two sections by the interconnection ring main unit, the section close to the substation is the front section of the line, and the other section is the rear section of the line;

[0040] When the fault point is located within the front section of an outgoing line, the line section from the fault point to the interconnecting ring network cabinet in the middle of the current outgoing line is transferred to the rear section of the line of the corresponding interconnected outgoing line, and the rear section of the line of the current outgoing line is transferred to the front section of the line of the corresponding interconnected outgoing line; when the fault point is located within the rear section of an outgoing line, the line end from the fault point to the current outgoing line is transferred to the front section of the line of the corresponding interconnected outgoing line.

[0041] More specifically, when the fault point is located within the front section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; then disconnect the connection between the connecting ring main unit in the middle of the current outgoing line and the rear section of the line to isolate the front section of the line from the rear section of the line; close the normally open switch of the connecting ring main unit in the middle of the current outgoing line to connect the front section of the line of the current outgoing line with the rear section of the line of the corresponding interconnected outgoing line; close the normally open switch of the connecting ring main unit connected to the end of the current outgoing line to connect the rear section of the line of the current outgoing line with the front section of the line of the corresponding interconnected outgoing line;

[0042] When the fault point is located within the rear section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; close the normally open switch of the interconnecting ring network cabinet connected to the end of the current outgoing line to connect the rear section of the current outgoing line with the front section of the corresponding interconnected outgoing line.

[0043] like Figure 5As shown, a new type of windmill-shaped distribution network connection structure including four substations is shown, and the network forms a four-petal windmill-like structure. When a circuit breaker k0 in the front section of the line trips due to the activation of the protection device and the reclosing fails, the circuit breaker k1 adjacent to the tripped circuit breaker k0 is first disconnected to isolate the faulty line section, and then the main line section breaker k2 (normally closed switch) of the connecting ring main unit in the middle of the current faulty outgoing line is disconnected to isolate the front section of the line and the rear section of the line, and the end circuit breaker k3 (normally open switch) of the interconnected line with the connecting ring main unit in the middle of the current faulty outgoing line is closed, and the load of the front section of the line of the current faulty outgoing line is transferred to the end of this interconnected outgoing line; then the circuit breaker k4 (normally open switch) of the connecting ring main unit connected to the rear section of the line of the current faulty outgoing line is closed, and the load of the rear section of the line of the current faulty outgoing line is transferred to the front section of the line of the interconnected outgoing line. In this fault situation where the most load needs to be transferred, the load of the faulty outgoing line is transferred by two lines respectively. Therefore, in theory, as long as the maximum load rate of the lines in the grid of the four-petal windmill structure is below 66%, load transfer can be performed. When the fault only occurs in the rear section of the line, it is only necessary to disconnect the circuit breaker adjacent to the tripped circuit breaker when the reclosing fails, isolate the faulty line section, and then close the circuit breaker of the interconnection ring main unit connected to the rear section of the current faulty outgoing line, and transfer the load of the rear section of the current faulty outgoing line to the front section of the interconnected outgoing line to restore power supply; load transfer can also be performed when the maximum load rate is below 66%.

[0044] During the development and construction of the power grid, Figures 1 to 3 The development process drawn is a gradual construction according to the increase in the number of substations in the power supply area. During the construction overload, only new lines and ring network cabinets are added, and there is no demolition, reconnection or diversion of old lines.

[0045] The novel windmill-shaped distribution network connection structure and load transfer method provided in the above embodiment have the following advantages:

[0046] 1. High line carrying capacity and operational flexibility: Compared with the single-ring network and single-connection wiring method of traditional networking, if the reliability of power supply is to be guaranteed, the load can be transferred by opening and closing the circuit breaker to ensure that users do not lose power after a fault occurs in any line segment at any time. The average load rate of the two lines that make up a wiring group is required to be controlled within 50%. Otherwise, it may cause overload problems on non-fault lines during load transfer. After networking with the new windmill-shaped distribution network wiring structure provided by the present invention, since each line is divided into two front and rear sections, each section is separately transferred by other lines for backup, and each line only needs to reserve half of the load power supply margin of the interconnected lines, so the average load rate in each wiring group only needs to be controlled at 66% to ensure power supply reliability. At the same time, a higher load rate operating range can better adapt to the random development of distributed power sources.

[0047] 2. Low network construction cost: Since the average maximum load rate is increased from 50% to 66%, the number of lines required in the region can be reduced at the planning level, and the demand for line channels can be reduced. Through the use of multiple types of nested use, it can adapt to the development and changes of surrounding substations and substation outgoing line intervals. In the process of network development of single-tie and single-ring network wiring modes, it is a common phenomenon that the number of outgoing lines from substations on both sides of the outgoing line is inconsistent. It is inevitable that multiple liaison lines will be used for transition. When it is subsequently changed to single-tie and single-ring network wiring, it is necessary to dismantle and reconnect redundant interconnection lines and switches, resulting in a certain amount of waste of infrastructure content. The new windmill-shaped distribution network wiring structure proposed in the present invention will not have problems such as changes in main and branch lines, line diversion, and dismantling during the development and construction of the power grid, thereby reducing the construction cost during the transition of grid construction.

[0048] 3. The networking logic and the action logic of distribution automation after line failure are simple and the networking is standardized, which will not lead to the problem of complex interconnection line relationships and difficult structural analysis caused by multi-connection wiring methods.

[0049] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0050] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A new type of windmill-shaped distribution network connection structure, characterized in that: Applicable to a power supply area including at least two substations; The outgoing line of each substation is evenly divided into two sections according to the distribution transformer capacity or actual load data through a contact ring main unit; The interconnecting ring main unit on each outgoing line is connected to the end of another interconnected outgoing line by a normally open switch, so that the outgoing lines of each substation are nested and connected with each other, forming an N-petal windmill-like structure, where N is the number of substations; When the number of outgoing lines of all substations is not equal, windmill-like structures with different numbers of petals are used for mixing; The number of outgoing lines of N substations are A1, A2, ...A N-2 , A N-1 , A N , and A1≤A2≤…≤A N-2 ≤A N-1 ≤A N When A1 is constructed with N petals, A2 is constructed with N-1 petals, A N-1 - A N-2 A 2-petal windmill structure, the remaining A N - A N-1 The outgoing lines form a single ring network or a single radiation in the traditional networking mode.

2. The novel windmill-shaped power distribution network connection structure according to claim 1 is characterized in that: Each combined ring main unit has three incoming switches, including one normally open switch and two normally closed switches; the lines connected to the two normally closed switches are the middle sections of the corresponding outgoing trunk lines, and the lines connected to the normally open switches are the ends of another interconnected outgoing line.

3. The novel windmill-shaped power distribution network connection structure according to claim 1 is characterized in that: The number of substations in the power supply area shall be at least three.

4. A load transfer method based on the novel windmill-shaped distribution network connection structure according to any one of claims 1 to 3, characterized in that: The steps include: Assume that an outgoing line is divided into two sections by the interconnection ring main unit, the section close to the substation is the front section of the line, and the other section is the rear section of the line; When the fault point is within the front section of an outgoing line, the line section from the fault point to the connecting ring main unit in the middle of the current outgoing line is transferred to the rear section of the corresponding interconnected outgoing line, and the rear section of the current outgoing line is transferred to the front section of the line with the corresponding interconnected outgoing line; When the fault point is located within the rear section of an outgoing line, the end of the line from the fault point to the current outgoing line is transferred to the front section of the line corresponding to the interconnected outgoing line.

5. The load transfer method according to claim 4, characterized in that: When the fault point is located within the front section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; Then disconnect the connection ring main unit in the middle of the current outgoing line from the rear section of the line to isolate the front section of the line from the rear section of the line; close the normally open switch of the connection ring main unit in the middle of the current outgoing line to connect the front section of the line of the current outgoing line with the rear section of the line of the corresponding interconnected outgoing line; close the normally open switch of the connection ring main unit connected to the end of the current outgoing line to connect the rear section of the line of the current outgoing line with the front section of the line of the corresponding interconnected outgoing line; When the fault point is located within the rear section of an outgoing line: first disconnect the circuit breaker adjacent to the fault point to isolate the faulty line section; Close the normally open switch of the interconnection ring main unit connected to the end of the current outgoing line to connect the rear section of the line of the current outgoing line with the front section of the line of the corresponding interconnected outgoing line.

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