Selection method of interconnection points based on source-load center of electricity supply area

Abstract

The method for selecting an interconnection point based on the source-load center of an electrical supply area according to the present invention includes the steps of interconnecting two electrical supply areas using a DC bus with a flexible interconnection system, defining one of the two electrical supply areas whose total distributed power is greater than its total load power as the source electrical supply area, defining one of the two electrical supply areas whose total distributed power is less than its total load power as the load electrical supply area, calculating a net source value of the source electrical supply area and a net load value of the load electrical supply area, calculating a source center of the source electrical supply area and a load center of the load electrical supply area, and determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value. This application can be specifically analyzed based on the actual situations of different electrical supply areas, and in most cases, the method for selecting an interconnection point based on the source-load center of an electrical supply area according to the present invention is far superior to conventional front-end or rear-end interconnection methods in terms of both line loss and voltage deviation, and therefore, it is believed that this application is of great significance for the actual selection of interconnection points in electrical supply areas.

Description

[Technical Field]

[0001] The present application relates to the technical field of photovoltaic power generation, and in particular to a method for selecting interconnection points based on source-load centerlines of an electricity supply area. [Background technology]

[0002] Currently, solar power generation in small buildings in urban areas and rooftop solar power generation in rural areas are often connected to the power grid via low-voltage lines, but when distributed solar power generation is connected, the voltage on the lines increases. The greater the power of the accessed distributed solar power generation, the more significant the voltage increase effect on the lines, resulting in a large deviation in the node voltage.

[0003] Flexible interconnection of low-voltage distribution electricity supply areas not only enables dynamic capacity expansion of interconnected electricity supply areas, but also reduces line voltage deviations and avoids voltage exceedance problems by selecting appropriate interconnection nodes. Due to the inherent complementarity between source electricity supply areas and load electricity supply areas, interconnection between two electricity supply areas typically involves selecting one source electricity supply area and one load electricity supply area. Conventional front-end and end-end interconnection methods only qualitatively select interconnection nodes based on the characteristics of concentrated access by distributed solar power generation and loads, making it difficult to ensure accuracy in the actual selection of interconnection points. This application proposes the concepts of source center and load center of electricity supply areas using the definitions of moment and center of gravity, and further proposes a method for selecting interconnection points between electricity supply areas that can be quantitatively analyzed. Summary of the Invention

[0004] This application provides a method for selecting an interconnection point based on the source-load center of an electricity supply area to solve the problem that conventional front-end and end-end interconnection methods only qualitatively select an interconnection node based on the characteristics of concentrated access of distributed solar power generation and loads, making it difficult to guarantee accuracy in the actual selection of the interconnection point.

[0005] The method for selecting interconnection points based on the source-load center of an electrical supply area according to the present application comprises: a flexible interconnection system interconnecting two electrical service areas by a DC bus; A step of defining one of the two electricity supply areas, in which the total distributed power source power is greater than the total load power, as a source electricity supply area; A step of defining one of the two electricity supply areas in which the total distributed power source power is smaller than the total load power as a load electricity supply area; Calculating a net source value of the source electricity supply area and a net load value of the load electricity supply area; calculating a source center of the source electrical supply area and a load center of the load electrical supply area; and determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value.

[0006] Optionally, the step of calculating the net source value of the source electrical supply area and the net load value of the load electrical supply area includes: Subtract the total load power from the total distributed power in the source electricity supply area, and the resulting difference is the net source value, S A and The total load power of the load electricity supply area is subtracted from the total distributed power supply power, and the resulting difference is the net load value, L B and

[0007] Optionally, the step of calculating the source center of the source electrical supply area comprises: From the end of the line, traverse the nodes in the source electricity supply area, sequentially A1, A2, ..., AN where N is the total number of nodes in the source electricity supply area, The source center of the source electricity supply area is designated as point E, and the distance from point E to the transformer of the source electricity supply area is calculated using the following formula:

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[0008] Optionally, the step of calculating the load center of the load electrical supply area includes: From the end of the line, traverse the nodes in the road electricity supply area, sequentially B1, B, ..., B M where M is the total number of nodes in the road electricity supply area, The load center of the load electricity supply area is designated as point F, and the distance from point F to the transformer of the load electricity supply area is calculated using the following formula:

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[0009] Optionally, the step of determining the interconnection points based on the source center and the load center from the comparison result of the net source value and the net load value includes: S A =L B If so, the node closest to the source center point E of the source electrical supply area and the node closest to the load center point F of the load electrical supply area are selected as interconnection points.

[0010] Optionally, the step of determining the interconnection points based on the source center and the load center from the comparison result of the net source value and the net load value includes: S A >L B If so, from the end of the source electrical supply area to the tip, K and selecting as interconnection points the node closest to point P in the source electrical supply area and the node closest to point F in the load electrical supply area; Node A K satisfies the following conditions,

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[0011] Optionally, the step of determining the interconnection points based on the source center and the load center from the comparison result of the net source value and the net load value includes: S A <L B If the load is supplied from the end of the electrical supply area to the end, Jand selecting as interconnection points the node closest to point E in the source electrical supply area and the node closest to point Q in the load electrical supply area; Node B J satisfies the following conditions,

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[0012] As is apparent from the above technical proposal, the method for selecting an interconnection point based on the source-load center of an electrical supply area according to the present application includes the steps of: interconnecting two electrical supply areas using a flexible interconnection system via a DC bus; defining one of the two electrical supply areas whose total distributed power source power is greater than the total load power as the source electrical supply area; defining one of the two electrical supply areas whose total distributed power source power is less than the total load power as the load electrical supply area; calculating a net source value of the source electrical supply area and a net load value of the load electrical supply area; calculating a source center of the source electrical supply area and a load center of the load electrical supply area; and determining an interconnection point based on the source center and load center from a comparison result of the net source value and the net load value.

[0013] Compared with the prior art, the present application has the following significant advantages: The present application can be specifically analyzed based on the actual conditions of different electrical supply areas, and in most cases, the method of selecting interconnection points based on the source-load center of the electrical supply area according to the present application is far superior to the traditional leading-edge interconnection method or terminal-edge interconnection method in terms of both line loss and voltage deviation, so the present application is considered to be of great significance for the actual selection of interconnection points in electrical supply areas. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a flowchart of a method for selecting an interconnection point based on a source-load center of an electrical supply area according to the present application. [Figure 2] 1 is a schematic diagram of a step of obtaining an interconnection point by comparing the magnitude of a net source value and a net load value in a method of selecting an interconnection point based on the source-load center of an electrical supply area according to the present application. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following examples are described in detail, and examples are illustrated in the drawings. When the following description refers to the drawings, the same numerals represent the same or similar elements in different drawings unless otherwise specified. The embodiments described in the following examples do not necessarily represent all embodiments that are compatible with the present application. They are merely examples that are compatible with some aspects of the present application as detailed in the claims.

[0016] Photovoltaic power generation uses solar cells to directly convert solar energy into electrical energy based on the principle of the photovoltaic effect. Whether used independently or grid-connected, a photovoltaic power generation system mainly consists of three parts: solar panel (component), controller, and inverter. Photovoltaic power generation equipment is highly integrated, reliable, stable, has a long service life, and is easy to install and maintain. In theory, photovoltaic technology can be used in any situation where power is required, and photovoltaic power sources are ubiquitous, from household power sources to spacecraft, from toys to megawatt-class power plants.

[0017] Photovoltaic power generation can be divided into stand-alone photovoltaic power generation, grid-connected photovoltaic power generation, and distributed photovoltaic power generation. Distributed photovoltaic power generation systems, also known as distributed power generation or distributed energy supply, utilize small photovoltaic power supply systems installed at or near the electricity-using site to meet specific user needs, support the economical operation of the existing power grid, or simultaneously meet both needs. The basic equipment in a distributed photovoltaic power generation system includes solar cell components, a solar cell array mounting system, a DC combiner box, a DC distribution board, a grid-connected inverter, and an AC distribution board, as well as power supply system monitoring equipment and environmental monitoring equipment. In a solar power generation system, the solar cell component array converts solar energy into electrical energy and outputs it as electrical energy. This energy is then sent centrally to the DC distribution board via the DC combiner box, and then converted back to AC by the grid-connected inverter to supply the building's loads. Any remaining or insufficient power is regulated by the associated power grid.

[0018] FIG. 1 is a flowchart of a method for selecting interconnection points based on source-load center of an electric power supply area according to the present application, the method comprising: a flexible interconnection system interconnecting two electrical service areas by a DC bus; A step of defining one of the two electricity supply areas, in which the total distributed power source power is greater than the total load power, as a source electricity supply area; A step of defining one of the two electricity supply areas in which the total distributed power source power is smaller than the total load power as a load electricity supply area; Calculating a net source value of the source electricity supply area and a net load value of the load electricity supply area; calculating a source center of the source electrical supply area and a load center of the load electrical supply area; and determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value.

[0019] In one embodiment, the flexible interconnection system interconnects two electrical supply areas by a DC bus, one of which is defined as a source electrical supply area, where the total distributed power of the electrical supply area is greater than the total load power, and the other is defined as a load electrical supply area, where the total distributed power of the electrical supply area is less than the total load power. The interconnection point optimization method of the present application includes three parts: source-centric calculation, load-centric calculation, and optimized selection of interconnection points.

[0020] In one embodiment, the flexible interconnection of low-voltage distribution electrical service areas can not only realize dynamic capacity increase of the interconnected electrical service areas, but also reduce the voltage deviation of the line and avoid the problem of exceeding the voltage limit by selecting appropriate interconnection nodes.

[0021] Furthermore, the step of calculating the net source value of the source electricity supply area and the net load value of the load electricity supply area includes: Subtract the total load power from the total distributed power in the source electricity supply area, and the resulting difference is the net source value, S A and The total load power of the load electricity supply area is subtracted from the total distributed power supply power, and the resulting difference is the net load value. B and

[0022] In one embodiment, calculation of net source and net load values ​​informs subsequent interconnect point selection.

[0023] Furthermore, the step of calculating the source center of the source electricity supply area includes: From the end of the line, traverse the nodes in the source electricity supply area, sequentially A1, A2, ..., A N where N is the total number of nodes in the source electricity supply area, The source center of the source electricity supply area is designated as point E, and the distance from point E to the transformer of the source electricity supply area is calculated using the following formula:

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[0024] In one embodiment, the distance to the transformer in the source electricity supply area calculated by the above formula is d E The position at this point is the source center of the source electrical supply area.

[0025] Furthermore, the step of calculating the road center of the road electricity supply area includes: From the end of the line, traverse the nodes in the road electricity supply area, sequentially B1, B, ..., B M where M is the total number of nodes in the road electricity supply area, The load center of the load electricity supply area is designated as point F, and the distance from point F to the transformer of the load electricity supply area is calculated using the following formula:

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[0026] In one embodiment, the distance to the transformer of the load electricity supply area calculated by the above formula is d F The position becomes the road center of the road electricity supply area.

[0027] FIG. 2 is a schematic diagram of the steps of selecting an interconnection point by comparing the magnitude of the net source value and the net load value in the method of selecting an interconnection point based on the source-load center of an electrical supply area according to the present invention. A and L B The magnitude of determines the electrical supply area to which the interconnection point location will shift, and S A >L B When the interconnection point location is shifted towards the source electrical supply area, S A <L B When the position of the interconnection point shifts towards the road electrical supply area, S A =L B If ,then the optimal interconnection point will be the node closest to the original source and load center points.

[0028] Furthermore, the step of determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value includes: S A =L B If so, the node closest to the source center point E of the source electrical supply area and the node closest to the load center point F of the load electrical supply area are selected as interconnection points.

[0029] Furthermore, the step of determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value includes: S A >L B If so, from the end of the source electrical supply area to the tip, K and selecting as interconnection points the node closest to point P in the source electrical supply area and the node closest to point F in the load electrical supply area; Node A K satisfies the following conditions,

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[0030] In one embodiment, the source electrical supply area A1 node to A K The power of each node is P A1 From P AK From the end of the electricity supply area A to the tip, K The source load is accumulated for each node from node A1 to node A2. K-1 The total net source value up to the node is LB Smaller, A1 node to A K The total net source value up to the node is L B That's it, from A1 node to A K The distance from the source electricity supply area of ​​the node to the transformer is d A1 From d AK and from A1 node to A K The source center to the node is designated as point P, and the node closest to point P in the source electrical supply area and the node closest to point F in the load electrical supply area are selected as interconnection points.

[0031] Furthermore, the step of determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value includes: S A <L B If the load is supplied from the end of the electrical supply area to the end, J and selecting as interconnection points the node closest to point E in the source electrical supply area and the node closest to point Q in the load electrical supply area; Node B J satisfies the following conditions,

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[0032] In one embodiment, from the end of the load electrical supply area to the tip, Node B J The source load is accumulated for each node up to B1. J The total net load value of a node is S A The following is true: B1 to B J+1 The total net load of the node is S A Larger, B1 node to B J The distance to the transformer in the load electrical supply area of ​​the node is d B1 From d BJ From B1 node to B J The source center to the node is designated as point Q, and the node closest to point E in the source electrical supply area and the node closest to point Q in the load electrical supply area are selected as interconnection points.

[0033] The present application provides a method for selecting an interconnection point based on a source-load center of an electrical supply area, the method including the steps of: interconnecting two electrical supply areas with a flexible interconnection system via a DC bus; defining one of the two electrical supply areas whose total distributed power is greater than its total load power as a source electrical supply area; defining one of the two electrical supply areas whose total distributed power is less than its total load power as a load electrical supply area; calculating a net source value of the source electrical supply area and a net load value of the load electrical supply area; calculating a source center of the source electrical supply area and a load center of the load electrical supply area; and determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value. Compared with the prior art, the present application has the following significant advantages: This application can be specifically analyzed based on the actual conditions of different electrical supply areas, and in most cases, the method of selecting interconnection points based on the source-load center of the electrical supply area according to this application is far superior to the traditional front-end interconnection method or terminal interconnection method in terms of line loss and voltage deviation, so this application is considered to be of great significance to the actual selection of interconnection points in electrical supply areas.

Claims

1. a flexible interconnection system interconnecting two electrical service areas by a DC bus; defining one of the two electricity supply areas in which the total distributed power source power is greater than the total load power as a source electricity supply area; A step of defining one of the two electricity supply areas in which the total distributed power source power is smaller than the total load power as a load electricity supply area; Calculating a net source value of the source electricity supply area and a net load value of the load electricity supply area; calculating a source center of the source electrical supply area and a load center of the load electrical supply area; and determining an interconnection point based on the source center and load center from a comparison result of the net source value and the net load value.

2. The step of calculating the net source value of the source electricity supply area and the net load value of the load electricity supply area includes: The total load power is subtracted from the total distributed power supply power in the source electricity supply area, and the resulting difference is taken as the net source value, S Ａ and The total load power of the load electricity supply area is subtracted from the total distributed power supply power, and the resulting difference is the net load value. Ｂ 2. The method for selecting interconnection points based on source load centers of an electrical supply area according to claim 1, further comprising the steps of:

3. The step of calculating the source center of the source electricity supply area includes: From the end of the line, traverse the nodes in the source electricity supply area, and １ , A ２ , ..., A Ｎ where N is the total number of nodes in the source electricity supply area, The source center of the source electricity supply area is designated as point E, and the distance from point E to the transformer of the source electricity supply area is calculated using the following formula: [Equation 1] Here, P.A. Ｎ is the power of the corresponding node, and dA Ｎ 3. The method for selecting interconnection points based on source load center of an electrical supply area according to claim 2, wherein: ∑ i = 1 i ∑ ...

4. The step of calculating the road center of the road electricity supply area includes: From the end of the line, traverse the nodes in the road electricity supply area, and then B １ , B, ..., B Ｍ where M is the total number of nodes in the load electricity supply area; The load center of the load electricity supply area is designated as point F, and the distance from point F to the transformer of the load electricity supply area is calculated using the following formula: [Equation 2] Here, PB Ｍ is the power of the corresponding node, dB Ｍ 4. The method for selecting interconnection points based on source load center of an electrical supply area according to claim 3, wherein: is the distance from the corresponding node to the transformer of the source electrical supply area.

5. determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value, S Ａ =L Ｂ 5. The method for selecting interconnection points based on the source / load centers of electrical supply areas according to claim 4, further comprising the step of selecting, as interconnection points, a node closest to a source center point E of the source electrical supply area and a node closest to a load center point F of the load electrical supply area when

6. determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value, S Ａ >L Ｂ From the end of the source electrical supply area to the tip, Ｋ and selecting as interconnection points the node closest to point P in the source electrical supply area and the node closest to point F in the load electrical supply area; Node A Ｋ satisfies the following conditions, [Equation 3] where: [Equation 4] Is A １ From node A Ｋ－１ is the total net source value of the node, [Equation 5] Is A １ From node A Ｋ is the total net source value of the node, Point P is A １ From node A Ｋ It is the source center to the node, and the formula for calculating the distance from point P to the transformer in the source electricity supply area is: [Equation 6] and Here, d ＡＫ 5. The method for selecting interconnection points based on source load center of an electrical supply area according to claim 4, wherein: is the distance from the corresponding node to the transformer of the source electrical supply area.

7. determining an interconnection point based on the source center and the load center from a comparison result of the net source value and the net load value, S Ａ <L Ｂ From the end of the load electrical supply area to the tip, Ｊ and selecting as interconnection points the node closest to point E in the source electrical supply area and the node closest to point Q in the load electrical supply area; Node B Ｊ satisfies the following conditions, [Equation 7] where: [Equation 8] Is B １ From node B Ｊ is the total net load value of the node, [Equation 9] Is B １ From node B Ｊ＋１ is the total net load value of the node, Point Q is B １ From node B Ｊ The formula for calculating the distance from the load center to the node, point Q to the transformer in the load electrical supply area is: [Equation 10] and Here, d ＢＪ 5. The method for selecting interconnection points based on source-load center of an electrical supply area according to claim 4, wherein: is the distance from the corresponding node to the transformer of the load electrical supply area.

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