Interconnection contact point selection method based on source and load centers of station areas

Abstract

The present application provides an interconnection contact point selection method based on source and load centers of station areas. The method comprises: a flexible interconnection system interconnecting two station areas via a direct-current bus; defining one of the two station areas where a total distributed source power is greater a total load power as a source station area; defining one of the two station areas where a total distributed source power is less than a total load power as a load station area; calculating a net source value of the source station area and a net load value of the load station area; calculating a source center of the source station area and a load center of the load station area; and according to a comparison result of the net source value and the net load value, and on the basis of the source center and the load center, determining an interconnection contact point. In the present application, specific analysis can be performed on the basis of actual conditions of different station areas. In many cases, the line loss and voltage deviation of the interconnection contact point selection method based on source and load centers of station areas provided by the present application are significantly better than those of typical head-end and tail-end interconnection types. Hence, the present application is of significant importance for the practical selection of station area interconnection points.

Description

A method for selecting interconnection contact points based on the source-load center of the substation area Technical Field

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

[0002] Currently, small-scale urban building photovoltaic power generation and rural rooftop photovoltaic power generation are mostly connected to the distribution network through low-voltage lines. The integration of distributed photovoltaic power will increase the voltage of the line. The greater the power of the connected distributed photovoltaic power, the more obvious the increase in line voltage, which will cause larger node voltage deviations.

[0003] The flexible interconnection of low-voltage distribution substations can not only realize the dynamic capacity expansion of interconnected substations, but also the selection of appropriate interconnection nodes can reduce the voltage deviation on the line and avoid voltage over-limit problems. Since there is a natural complementarity between the source substation and the load substation, most of the interconnections between the two substations are carried out by selecting a source substation and a load substation. The traditional head-end interconnection and end-end interconnection methods only qualitatively select interconnection nodes based on the centralized characteristics of distributed photovoltaic and load access, and it is difficult to accurately grasp the actual selection of interconnection points. With the help of the definitions of moments and centers of gravity, this application proposes the concepts of source center and load center of the substation, and then proposes a method for selecting substation interconnection points that can be quantitatively analyzed.

[0004] Summary of the Invention

[0005] This application provides a method for selecting interconnection connection points based on the source-load center of the substation area to solve the problem that traditional head-end interconnection and end-end interconnection methods only qualitatively select interconnection nodes based on the centralized characteristics of distributed photovoltaic and load access, and it is difficult to accurately grasp the actual selection of interconnection points.

[0006] The present application provides a method for selecting an interconnection contact point based on a source-load center in an area, the method comprising:

[0007] The flexible interconnection system interconnects the two substations through a DC bus;

[0008] The one of the two substations where the total distributed generation power is greater than the total load power is defined as the source substation;

[0009] The one of the two substations where the total distributed generation power is less than the total load power is defined as the load substation;

[0010] Calculate and obtain the net source value of the source station area and the net load value of the load station area;

[0011] Calculate and obtain the source center of the source area and the load center of the load area;

[0012] According to the comparison result of the net source value and the payload value, an interconnection contact point is determined based on the source center and the payload center.

[0013] Optionally, the step of calculating and obtaining the net source value of the source area and the payload value of the payload area includes:

[0014] The total distributed power in the source area minus the total load power is the net source value, which is denoted as S A ;

[0015] The difference between the total load power of the load area and the total distributed power is the net load value, which is denoted as L B .

[0016] Optionally, the step of calculating and obtaining the source center of the source area includes:

[0017] Starting from the end of the line, traverse the nodes of the source area and record them as A1, A2, ..., A N , where N is the total number of nodes in the source area;

[0018] The source center of the source area is recorded as point E, and the distance calculation formula from point E to the transformer in the source area is:

[0019] Where, PA N is the power of the corresponding node, dA N is the distance between the corresponding node and the source transformer.

[0020] Optionally, the step of calculating and obtaining the load center of the load platform area includes:

[0021] Starting from the end of the line, traverse the nodes in the platform area and record them as B1, B, ..., B M , where M is the total number of nodes in the platform area;

[0022] The load center of the load platform is recorded as point F, and the distance calculation formula from point F to the load platform is:

[0023] Where PB M is the power of the corresponding node, dB M is the distance between the corresponding node and the source transformer.

[0024] Optionally, the step of determining the interconnection contact point based on the source center and the load center according to the comparison result of the net source value and the payload value includes:

[0025] If S A =L B , then the node closest to the source center point E in the source area and the node closest to the load center point F in the load area are selected as the interconnection contact points.

[0026] Optionally, the step of determining the interconnection contact point based on the source center and the load center according to the comparison result of the net source value and the payload value includes:

[0027] If S A >L B , then starting from the end of the source area to the head end, the source load is accumulated node by node until node A K , the following conditions are met:

[0028] Where, From A1 to A K-1 The total net source value of the node, From A1 to A K The total net source value of the node;

[0029] A1 node to A K The source center of the node is recorded as point P, and the distance calculation formula from point P to the source transformer is:

[0030] Where, d AK is the distance between the corresponding node and the source transformer;

[0031] The node closest to point P in the source area and the node closest to point F in the load area are selected as interconnection points.

[0032] Optionally, the step of determining the interconnection contact point based on the source center and the load center according to the comparison result of the net source value and the payload value includes:

[0033] If S A <L B , then starting from the end of the load area to the head end, the source load is accumulated node by node until node B J , the following conditions are met:

[0034] Where, From B1 to B J The total payload value of the node, From B1 to B J+1 The total payload value of the node;

[0035] B1 node to B J The load center of the node is recorded as point Q. The distance calculation formula from point Q to the load platform is:

[0036] Where, d BJ is the distance between the corresponding node and the load station;

[0037] The node closest to point E in the source area and the node closest to point Q in the load area are selected as interconnection points.

[0038] It can be seen from the above technical solution that the present application provides a method for selecting an interconnection connection point based on the source-load center of the substation, and the method includes: a flexible interconnection system interconnects two substations through a DC bus; one of the two substations in which the total distributed power source power is greater than the total load power is defined as the source substation; one of the two substations in which the total distributed power source power is less than the total load power is defined as the load substation; the net source value of the source substation and the net load value of the load substation are calculated; the source center of the source substation and the load center of the load substation are calculated; and according to the comparison result of the net source value and the net load value, the interconnection connection point is determined based on the source center and the load center.

[0039] Compared with the existing technology, the present application has the following significant advantages: the present application can conduct specific analysis based on the actual conditions of different substations. In many cases, the line loss and voltage deviation of the interconnection connection point selection method based on the substation source-load center provided by the present application are far better than the typical head-end interconnection and end-end interconnection types. Therefore, the present application is of great significance for the actual selection of substation interconnection points. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a flow chart of a method for selecting an interconnection contact point based on a source-load center in an area provided by this application;

[0041] FIG2 is a schematic diagram of the steps of obtaining the interconnection connection point by comparing the net source value and the payload value in a method for selecting the interconnection connection point based on the source-load center of the substation area provided by the present application. DETAILED DESCRIPTION

[0042] The following embodiments are described in detail, with examples shown in the accompanying drawings. When the following description refers to the drawings, identical numbers in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following embodiments are not intended to represent all possible implementations consistent with the present application. They are merely examples consistent with certain aspects of the present application as detailed in the claims.

[0043] Photovoltaic power generation uses solar cells to convert sunlight directly into electricity, based on the photovoltaic effect. Whether used independently or connected to the grid, a photovoltaic power generation system primarily consists of three components: solar panels (modules), a controller, and an inverter. Photovoltaic power generation equipment is extremely sophisticated, reliable, stable, long-lasting, and easy to install and maintain. In theory, photovoltaic power generation technology can be used in any application requiring power, from spacecraft to household power supplies, from megawatt-class power plants to small toys. Photovoltaic power can be ubiquitous.

[0044] Solar photovoltaic power generation is categorized as stand-alone, grid-connected, and distributed. Distributed photovoltaic systems, also known as decentralized power generation or distributed energy supply, refer to smaller photovoltaic power generation systems deployed at or near user sites to meet specific user needs, support the economic operation of existing distribution networks, or both. The basic equipment of a distributed photovoltaic power generation system includes photovoltaic cell modules, photovoltaic array supports, DC combiner boxes, DC distribution cabinets, grid-connected inverters, AC distribution cabinets, and other equipment, as well as power supply system monitoring and environmental monitoring devices. Under solar radiation, the photovoltaic system's solar cell array converts solar energy into output electricity, which is then fed through a DC combiner box into a DC distribution cabinet. A grid-connected inverter then converts the electricity into AC power to supply the building's own loads. Excess or insufficient power is regulated through connection to the grid.

[0045] 1 is a flow chart of a method for selecting interconnection contact points based on a source-load center in an area provided by this application. The method includes:

[0046] The flexible interconnection system interconnects the two substations through a DC bus;

[0047] The one of the two substations where the total distributed generation power is greater than the total load power is defined as the source substation;

[0048] The one of the two substations where the total distributed generation power is less than the total load power is defined as the load substation;

[0049] Calculate and obtain the net source value of the source station area and the net load value of the load station area;

[0050] Calculate and obtain the source center of the source area and the load center of the load area;

[0051] According to the comparison result of the net source value and the payload value, an interconnection contact point is determined based on the source center and the payload center.

[0052] In one embodiment, the flexible interconnection system interconnects two substations through a DC bus. Among the two substations, one is defined as a source substation, and the total distributed power supply power of the substation is greater than the total load power; the other is defined as a load substation, and the total distributed power supply power of the substation is less than the total load power; the interconnection point optimization method provided in this application includes three parts: source center calculation, load center calculation and interconnection point optimization selection.

[0053] In one embodiment, the flexible interconnection of low-voltage distribution substations can not only achieve dynamic capacity expansion of interconnected substations and select appropriate interconnection nodes, but also reduce voltage deviation on the line and avoid voltage limit problems.

[0054] Furthermore, the step of calculating and obtaining the net source value of the source area and the net load value of the load area includes:

[0055] The total distributed power in the source area minus the total load power is the net source value, which is denoted as S A ;

[0056] The difference between the total load power of the load area and the total distributed power is the net load value, which is denoted as L B .

[0057] In one embodiment, the calculation of the net source value and the payload value provides decision support for the subsequent selection of the interconnection contact point.

[0058] Furthermore, the step of calculating and obtaining the source center of the source area includes:

[0059] Starting from the end of the line, traverse the nodes of the source area and record them as A1, A2, ..., A N , where N is the total number of nodes in the source area;

[0060] The source center of the source area is recorded as point E, and the distance calculation formula from point E to the transformer in the source area is:

[0061] Where, PA N is the power of the corresponding node, dA N is the distance between the corresponding node and the source transformer.

[0062] In one embodiment, the distance from the source station area obtained by the above formula is d E The location is the source center of the source area.

[0063] Furthermore, the step of calculating and obtaining the load center of the load platform area includes:

[0064] Starting from the end of the line, traverse the nodes in the platform area and record them as B1, B, ..., B M , where M is the total number of nodes in the platform area;

[0065] The load center of the load platform is recorded as point F, and the distance calculation formula from point F to the load platform is:

[0066] Where PB M is the power of the corresponding node, dB M is the distance between the corresponding node and the source transformer.

[0067] In one embodiment, the distance from the load area to the platform obtained by the above formula is d F The location is the center of the lotus area.

[0068] 2, which is a schematic diagram of the steps of obtaining interconnection points by comparing the net source value and the payload value in a method for selecting interconnection points based on the source-load center of the substation provided by this application. In one embodiment, S A With L B The size of determines to which area the location of the interconnection point is offset. If S A >L B , then the location of the interconnection point shifts toward the source station area; if S A <L B , then the location of the interconnection point shifts toward the load platform area; if S A =L B , then the optimal interconnection point is the node closest to the original source center and load center.

[0069] Furthermore, according to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center includes:

[0070] If S A =L B , then the node closest to the source center point E in the source area and the node closest to the load center point F in the load area are selected as the interconnection contact points.

[0071] Furthermore, according to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center includes:

[0072] If S A >L B , then starting from the end of the source area to the head end, the source load is accumulated node by node until node A K , the following conditions are met:

[0073] Where, From A1 to A K-1 The total net source value of the node, From A1 to A K The total net source value of the node;

[0074] A1 node to A K The source center of the node is recorded as point P, and the distance calculation formula from point P to the source transformer is:

[0075] Where, d AK is the distance between the corresponding node and the source transformer;

[0076] The node closest to point P in the source area and the node closest to point F in the load area are selected as interconnection points.

[0077] In one embodiment, the source area A1 node to AK The power of the nodes is denoted as P A1 to P AK Starting from the end of area A, the source load is accumulated node by node toward the head end until node A K So far, from A1 node to A K-1 The total net source value of the node is less than L B , and from node A1 to A K The total net source value of the node is greater than or equal to L B , A1 node to A K The distance between the node and the source transformer is denoted as d A1 to d AK , A1 node to A K The source center of the node is recorded as point P, and the node closest to point P in the source area and the node closest to point F in the load area are selected as interconnection points.

[0078] Furthermore, according to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center includes:

[0079] If S A <L B , then starting from the end of the load area to the head end, the source load is accumulated node by node until node B J , the following conditions are met:

[0080] Where, From B1 to B J The total payload value of the node, From B1 to B J+1 The total payload value of the node;

[0081] B1 node to B J The load center of the node is recorded as point Q. The distance calculation formula from point Q to the load platform is:

[0082] Where, d BJ is the distance between the corresponding node and the load station;

[0083] The node closest to point E in the source area and the node closest to point Q in the load area are selected as interconnection points.

[0084] In one embodiment, starting from the end of the load area, the source load is accumulated node by node toward the head end until the node B J So far, from node B1 to node B J The total payload value of the node is less than or equal to S A , and from node B1 to B J+1 The total payload value of the node is greater than S A , B1 node to BJ The distance between the node and the load station is denoted as d B1 to d BJ , B1 node to B J The source center of the node is recorded as point Q, and the node closest to point E in the source area and the node closest to point Q in the load area are selected as interconnection points.

[0085] The present application provides a method for selecting an interconnection point based on a substation source-load center, the method comprising: a flexible interconnection system interconnects two substations through a DC bus; one of the two substations having a total distributed power source power greater than a total load power is defined as a source substation; one of the two substations having a total distributed power source power less than a total load power is defined as a load substation; calculating the net source value of the source substation and the net load value of the load substation; calculating the source center of the source substation and the load center of the load substation; and determining the interconnection point based on the source center and the load center according to the 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: the present application can perform specific analysis according to the actual conditions of different substations. In many cases, the line loss and voltage deviation of the method for selecting an interconnection point based on a substation source-load center provided by the present application are much better than those of the typical head-end interconnection type and the end-end interconnection type. Therefore, the present application is of great significance for the actual selection of substation interconnection points.

Claims

1. A method for selecting interconnection contact points based on the source-load center of the substation area, characterized in that: The method comprises: The flexible interconnection system interconnects the two substations through a DC bus; The one of the two areas where the total distributed generation power is greater than the total load power is defined as the source area; The one of the two areas where the total distributed generation power is less than the total load power is defined as the load area; Calculate and obtain the net source value of the source station area and the net load value of the load station area; Calculate and obtain the source center of the source area and the charge center of the charge area; According to the comparison result of the net source value and the payload value, an interconnection contact point is determined based on the source center and the payload center.

2. According to claim 1, a method for selecting interconnection contact points based on the source-load center of the substation area is characterized in that: The steps of calculating and obtaining the net source value of the source area and the net load value of the load area include: The total distributed power of the source area minus the total load power, the difference is the net source value, denoted as S A ; The difference between the total load power of the load area and the total distributed power is the net load value, denoted as L B .

3. The method for selecting interconnection contact points based on the source-load center of the substation area according to claim 2 is characterized in that: The step of calculating and obtaining the source center of the source station area comprises: Starting from the end of the line, we traverse the nodes in the source area and record them as A1, A2, ..., A N , where N is the total number of nodes in the source area; The source center of the source area is recorded as point E, and the distance calculation formula from point E to the source area transformer is: Where, PA N is the power of the corresponding node, dA N is the distance between the corresponding node and the source transformer.

4. The method for selecting interconnection contact points based on the source-load center of the substation area according to claim 3 is characterized in that: The step of calculating and obtaining the load center of the load platform area comprises: Starting from the end of the line, we traverse the nodes in the platform area and record them as B1, B, ..., B M , where M is the total number of nodes in the platform area; The load center of the load platform is recorded as point F, and the distance calculation formula from point F to the load platform is: Where PB M is the power of the corresponding node, dB M is the distance between the corresponding node and the source transformer.

5. The method for selecting interconnection contact points based on the source-load center of the substation area according to claim 4 is characterized in that: According to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center comprises: If S A =L B , then the node closest to the source center point E in the source area and the node closest to the load center point F in the load area are selected as the interconnection contact points.

6. The method for selecting interconnection contact points based on the source-load center of the substation area according to claim 4 is characterized in that: According to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center comprises: If S A >L B , then starting from the end of the source area, the source load is accumulated node by node until node A K , the following conditions are met: In the formula, From A1 to A K-1 The total net source value of the node, From A1 to A K The total net source value of the node; A1 node to A K The source center of the node is recorded as point P, and the distance calculation formula from point P to the source transformer is: Where, d AK is the distance between the corresponding node and the source transformer; The node closest to point P in the source area and the node closest to point F in the load area are selected as interconnection contact points.

7. The method for selecting interconnection contact points based on the source-load center of the substation area according to claim 4 is characterized in that: According to the comparison result of the net source value and the payload value, the step of determining the interconnection contact point based on the source center and the payload center comprises: If S A <L B , then starting from the end of the load platform area, the source load is accumulated node by node until node B J , the following conditions are met: In the formula, From B1 to B J The total payload value of the node, From B1 to B J+1 The total payload value of the node; B1 node to B J The load center of the node is recorded as point Q, and the distance calculation formula from point Q to the load platform is: Where, d BJ is the distance between the corresponding node and the load station; The node closest to point E in the source area and the node closest to point Q in the load area are selected as interconnection contact points.

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