A method and system for calculating the access capacity and assessing the carrying capacity of a power distribution network system.

Abstract

This invention discloses a method and system for calculating the accessibility capacity and assessing the carrying capacity of a distribution network system. The method includes accessibility capacity calculation and carrying capacity assessment. Accessibility capacity calculation is based on the accessibility capacity data of distribution transformers and 10kV lines, combined with a geographic map. The calculation is based on the criterion that the access of distributed power sources will not cause reverse overload or reverse power flow, thus calculating the accessibility capacity of distribution transformers and 10kV lines around a specified location and completing the equipment accessibility capacity calculation and accessibility level evaluation. The carrying capacity assessment is based on the load rate of grid equipment after the access of distributed power sources. It integrates information from the production management system and uses geographic maps combined with E-Charts charts to monitor the carrying capacity indicators of a region. This invention can guide the orderly and reasonable access of distributed power sources, reducing the risk of line or distribution transformer overload and voltage exceeding limits after power source access.

Description

Technical Field

[0001] This invention relates to the field of power system grid-source coordination, and in particular to a method and system for calculating the access capacity and assessing the carrying capacity of a distribution network system. Background Technology

[0002] The development of the power grid carries the mission of optimizing energy resource allocation, reducing energy consumption, effectively utilizing new energy sources, and promoting technological progress in emerging industries, and has become an important component of my country's energy strategy. As a crucial link in the construction of smart grids, with the widespread application of power electronic devices and the commissioning of large-capacity high-voltage direct current transmission, the characteristics of my country's power grid—"power electronics" and "strong DC, weak AC"—are becoming increasingly apparent. On the one hand, the new characteristics of the power grid directly affect the operation of generating units. On the other hand, the capacity of generating units is increasing year by year, and their operating conditions directly affect the safety of the power grid. Under this new situation, strengthening research on the coordination between generating units and the power grid is of great significance. Generator grid connection testing is a preventative test, an important part of power equipment operation and maintenance, and one of the effective means to ensure the safe operation of the power system. It is a crucial measure to prevent accidents or equipment damage and ensure safe operation.

[0003] Existing technologies primarily focus on monitoring the operational data of medium- and low-voltage distribution network lines and transformers already connected to the distribution master station system, enabling monitoring of their operational status, such as overload and fault conditions. However, when a high proportion of distributed generation (DG) sources are integrated, there is no effective way to guide the orderly and reasonable integration of DG sources, potentially leading to issues such as voltage exceeding limits and reverse overload on transformers / lines. Therefore, a solution is urgently needed to guide the orderly and reasonable integration of DG sources, reduce the management costs of DG integration, and assess the carrying capacity of DG sources, thereby mitigating the risks of line or transformer overload and voltage exceeding limits after DG integration. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method and system for calculating the access capacity and carrying capacity assessment of a distribution network system, which can effectively guide the orderly and reasonable access of distributed power sources, and reduce the risk of line or transformer overload and voltage exceeding limits after the access of distributed power sources.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] The method proposed in this invention includes accessibility capacity calculation and carrying capacity assessment. The specific steps are as follows:

[0007] S1. Accessible capacity calculation, including: based on the accessible capacity data of distribution transformers and 10kV lines, combined with a geographic map, to study the accessible capacity of distribution transformers and 10kV lines around a specified location, and to complete the accessible capacity calculation and accessibility level evaluation of the access equipment.

[0008] S2. Carrying capacity assessment, including: using the load rate of grid equipment after the access of distributed power sources as the basic criterion, integrating the ledger information of the production management system, and monitoring the carrying capacity index of the power grid area based on geographical maps and E-Charts charts.

[0009] Furthermore, the calculation of accessible capacity in step S1 includes the calculation of accessible capacity for lines and distribution transformers, the specific details of which are as follows:

[0010] (1) Calculation of line access capacity: Under the premise of ensuring the safety and stability of the power grid in operation, the calculation is carried out in combination with the current load of the line and the power sources, energy storage and loads that have been connected and have been clearly connected. The calculation is based on the judgment that the connection of distributed power sources does not cause reverse overload of 10kV lines and the power flow of the line directly connected to the upstream main transformer is reversed.

[0011] (2) Calculation of the capacity that can be connected to the distribution transformer: Under the premise of ensuring the safety and stability of the power grid in operation, the calculation is carried out in combination with the current load of the distribution transformer and the power sources, energy storage and loads that have been connected and have been clearly connected. The calculation is based on the judgment that the connection of the distributed power source does not cause the transformer area to be overloaded in reverse and the power flow of the transformer area directly connected to the 10kV line is reversed.

[0012] Furthermore, the specific calculation steps for capacity calculation in step S1 are as follows:

[0013] S101. Obtain the rated capacity of the line, the installed capacity of distributed photovoltaic power generation under the line, and the approved but not yet connected distributed photovoltaic power generation under the line from the electricity information collection system.

[0014] S102. Obtain the historical one-year line load profile curve from the DMS system, delete abnormal data, and obtain the minimum load.

[0015] S103. Calculate the minimum load rate of the line, divide the line into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavily loaded lines.

[0016] S104. Obtain the access capacity of the power supply bus of the line from the control cloud, and calculate the access capacity of the line using the self-absorption algorithm and the relative safety algorithm respectively. The smaller access capacity is the access capacity of the line.

[0017] S105. Obtain the rated capacity of the distribution transformer, the installed capacity of distributed photovoltaic power generation connected to the distribution transformer, and the approved but not yet connected distributed photovoltaic power generation capacity under the distribution transformer from the electricity information collection system.

[0018] S106. Obtain the historical one-year distribution transformer load profile curve from the electricity consumption information collection system, delete abnormal data, and obtain the minimum load.

[0019] S107. Calculate the minimum load rate of the distribution transformer, divide the line into load levels according to the minimum load rate, and mark them differently. At the same time, the heavily loaded distribution transformers are highlighted.

[0020] S108. Based on the access capacity of the line to which the distribution transformer belongs in step S104, calculate the access capacity of the distribution transformer using the self-absorption algorithm and the relative safety algorithm respectively. The smaller access capacity is the access capacity of the distribution transformer.

[0021] Furthermore, in step S103, the formula for calculating the minimum load rate is: minimum load rate = minimum load / rated capacity of distribution transformer * 100%; and the load is divided into three levels: no load, light load and heavy load according to the minimum load rate.

[0022] Furthermore, in step S104, the line's access capacity is calculated once when the application starts, and then calculated once per cycle according to the device's startup cycle. The specific calculation steps are as follows:

[0023] Step 1: Obtain the current carrying capacity of the incoming line switch;

[0024] Step 2: Obtain the installed capacity of distributed power sources that have been connected to the line, and obtain the installed capacity of distributed power sources that have been approved but not yet connected to the line.

[0025] Step 3, Historical Data Acquisition Rules: The data for the line is stored in a daily table. If the daily table exists, the data is retrieved; otherwise, it is skipped.

[0026] Step 4: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min ;

[0027] Step 5: Calculate the minimum equivalent load factor η min The current line's access capacity level is evaluated. The line level evaluation only considers the line's own load rate. The specific formula is as follows:

[0028] η min =P min / S e *100%

[0029] Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor η min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels.

[0030] Step 6: Calculate the line's connectable capacity using the self-absorption algorithm. The specific formula is as follows:

[0031] P ms =Se *(K r +η min )-P PF ;

[0032]

[0033] Where I is the current carrying capacity; P ms For the maximum capacity of newly added distributed power sources; K r The operating margin factor for the equipment is generally taken as 0.8 based on the assumption that the equipment is not under heavy load; P PF This refers to the installed capacity of distributed power sources that have been approved but not yet connected to the line, including the capacity of the distribution transformers connected to the line.

[0034] The line's access capacity is calculated using a relatively safe algorithm, with the specific formula as follows:

[0035] P ms =S e *0.8-P YJ -P PF ;

[0036] Among them, P YJ This refers to the installed capacity of distributed power sources already connected to the line, including the capacity of distribution transformers connected to the line.

[0037] Furthermore, in step S108, the available capacity of the distribution transformer is calculated once when the application is started, and then calculated weekly thereafter. The specific calculation steps are as follows:

[0038] Step 1: Obtain the rated capacity of the distribution transformer;

[0039] Step 2: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min Obtain the installed capacity P of the distributed power sources connected to the distribution transformer. YJ The approved but not yet connected distributed power generation capacity P PF ;

[0040] Step 3: Calculate the minimum equivalent load factor η min To evaluate the current line's available capacity level, the transformer level evaluation considers both the transformer's load factor and the load factor of the line it connects to. The specific formula is as follows:

[0041] η min =P min / S e *100%

[0042] Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor η minAccess levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels.

[0043] Step 4: Calculate the available capacity of the distribution transformer using the self-absorption algorithm. The specific formula is as follows:

[0044] P ms =S e *(K r +η min )-P PF ;

[0045]

[0046] The capacity that can be connected to the distribution transformer is calculated using a relatively safe algorithm. The specific formula is as follows:

[0047] P ms =S e -P YJ -P PF .

[0048] Furthermore, regarding the load-bearing capacity assessment described in step S2, before connecting distributed power sources, the connection point and voltage level should be determined to ensure that surrounding lines and transformers will not operate under overload conditions. The calculation scope of the load-bearing capacity assessment includes:

[0049] (1) If the distributed power source is connected to the low-voltage distribution network, the calculation scope is the distribution area and low-voltage line directly connected to the distributed power source.

[0050] (2) If the distributed power source is connected to the medium voltage distribution network and is connected in a T-connection manner, the calculation scope is the public line connected to the distributed power source by the T-connection. When the line is back-feeding, the upstream main transformer should be further evaluated. If it is directly connected to the low voltage bus of the substation by a dedicated line, the calculation scope is the main transformer equipment connected to the distributed power source.

[0051] Furthermore, the bearing capacity assessment described in step S2 specifically includes:

[0052] S201. Select either a relatively safe algorithm or a self-absorption algorithm to calculate the corresponding accessible capacity;

[0053] S202. Obtain the access capacity of the corresponding algorithm of the access location and compare it with the access capacity of the current input parameter.

[0054] S203. Based on the different comparison results, perform the following actions respectively:

[0055] (1) If the current capacity to be connected is greater than the available capacity, then feedback is given that it cannot be connected, and other available locations are calculated and recommended. When the connection location is a distribution transformer, other locations under the same line that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended. When the connection location is a line, other locations under the same substation that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended.

[0056] (2) If the current capacity to be accessed is less than the available capacity, then the access is approved. At the same time, the minimum equivalent load rate after access is calculated and the evaluation level is determined.

[0057] Furthermore, this invention also proposes a distribution network system accessibility calculation and carrying capacity assessment system, characterized in that it includes:

[0058] The access capacity calculation module includes a line access capacity calculation module and a distribution transformer access capacity calculation module. It is used to study the access capacity of distribution transformers and 10kV lines around a specified location based on the access capacity data of distribution transformers and 10kV lines, combined with a geographic map, and to complete the equipment access capacity calculation and accessibility level evaluation.

[0059] The carrying capacity assessment module is used to determine the load rate of grid equipment after the access of distributed power sources as the basic criterion. It integrates the ledger information of the production management system and realizes the monitoring of regional carrying capacity indicators based on geographic maps and E-Charts charts.

[0060] Furthermore, the specific details of the accessible capacity calculation module are as follows:

[0061] Step 1: Obtain the corresponding capacity data of the line from the electricity consumption information collection system;

[0062] Step 2: Obtain the historical one-year line load profile curve from the DMS system, delete abnormal data, and obtain the minimum load;

[0063] Step 3: Calculate the minimum load rate of the line, divide the line into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavily loaded lines.

[0064] Step 4: Obtain the access capacity of the power supply bus from the control cloud, and calculate the access capacity of the line using the self-absorption algorithm and the relative safety algorithm respectively. The smaller access capacity is the access capacity of the line.

[0065] Step 5: Obtain the corresponding capacity data of the distribution transformer from the electricity consumption information collection system;

[0066] Step 6: Obtain the historical one-year distribution transformer load profile curve from the electricity consumption information collection system, delete abnormal data, and obtain the minimum load;

[0067] Step 7: Calculate the minimum load rate of the distribution transformer, classify the line into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavy load distribution transformer.

[0068] Step 8: Based on the access capacity of the line to which the distribution transformer belongs, calculated in Step 4, calculate the access capacity of the distribution transformer using the self-absorption algorithm and the relative safety algorithm respectively. The smaller access capacity is the access capacity of the distribution transformer.

[0069] Furthermore, the carrying capacity assessment module specifically includes: selecting a relatively safe algorithm or a self-absorption algorithm, obtaining the access capacity of the corresponding algorithm at the access location, and comparing it with the capacity to be accessed based on the current input parameters; depending on the comparison result, the following actions are performed respectively:

[0070] (1) If the current capacity to be accessed is greater than the available capacity, then feedback is given that access is not possible, and other available access locations are calculated and recommended.

[0071] (2) If the current capacity to be accessed is less than the available capacity, then the access is approved. At the same time, the minimum equivalent load rate after access is calculated and the evaluation level is determined.

[0072] The present invention adopts the above technical solution, and its significant technical effects compared with the prior art are as follows:

[0073] This invention utilizes statistical analysis of the total output, power consumption, and output extremes of various types of distributed generation (DG) sources. It monitors abnormal operating conditions such as voltage exceeding limits and three-phase imbalance at DG grid connection points and connected transformers / lines. The invention calculates the connectable capacity of transformers based on the load factor of the distribution area and the power flow of the connected lines, and calculates the connectable capacity of lines based on the load factor of the line load factor and the power flow of the upstream main transformer. Finally, it assesses the carrying capacity of designated connection points using the load factor of grid equipment after DG connection as the primary criterion. This enables the calculation of the connectable capacity of 10kV buses, feeders, and transformers, guiding the orderly and rational connection of DG sources and reducing the management costs of DG absorption. It also enables the assessment of the DG carrying capacity of 10kV buses, feeders, and transformers, reducing the risk of line or transformer overload and voltage exceeding limits after DG connection. Attached Figure Description

[0074] Figure 1 This is a network architecture diagram of the present invention.

[0075] Figure 2 This is a flowchart illustrating the calculation of the line access capacity according to the present invention.

[0076] Figure 3 This is a flowchart illustrating the calculation process for the available capacity of distribution transformers according to the present invention.

[0077] Figure 4This is a flowchart illustrating the calculation of the available capacity of lines and distribution transformers using the self-absorption algorithm and the relative safety algorithm of this invention.

[0078] Figure 5 This is a flowchart of the load-bearing capacity analysis of the present invention. Detailed Implementation

[0079] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0080] To achieve the above objectives, this invention applies access capacity calculation and carrying capacity assessment to analyze the power access conditions of power lines and distribution transformers. Figure 1 This is a network architecture diagram of the present invention, introducing information on data sources, interaction methods, and synchronization frequencies. Accessible capacity calculation obtains the accessible capacity of the line power supply bus from the control cloud, and simultaneously obtains transformer area ledger information, line outgoing switch current carrying capacity, and line outgoing switch measurement sections from the DMS (Distribution Management System). Accessible capacity calculation and carrying capacity assessment obtain distributed photovoltaic ledger information and transformer area measurement sections from the electricity consumption information collection system. The interaction method for the accessible capacity of the line power supply bus is file transfer, synchronized on the 9th, 19th, and 29th of each month; the interaction method for distributed photovoltaic ledger information is an intermediate database, synchronized once a day; the interaction method for transformer area measurement sections is an intermediate database, synchronized with the previous day's data at 22:00; the interaction method for transformer area ledger information is file transfer, synchronized every 3 hours; the interaction method for line outgoing switch current carrying capacity is file transfer, synchronized once a day; the interaction method for line outgoing switch measurement sections is file transfer, synchronized every 5 minutes per day.

[0081] The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to the present invention includes the following steps:

[0082] S1. Accessible capacity calculation, including: based on the accessible capacity data of distribution transformers and 10kV lines, combined with a geographic map, to study the accessible capacity of distribution transformers and 10kV lines around a specified location, and to complete the accessible capacity calculation and accessibility level evaluation of the access equipment.

[0083] The calculation of the line's connectable capacity is performed under the premise of ensuring the safety and stability of the power grid during operation. It considers the current load on the line, as well as the already connected and confirmed connected power sources, energy storage, and loads. The criteria for calculation are that the connection of distributed power sources does not cause reverse reload on the 10kV line, and the power flow of the line directly connected to the upstream main transformer is reversed. For example... Figure 2 As shown, the specific steps for calculating the line's access capacity are as follows:

[0084] Step 1: Obtain the rated capacity of the line, the installed capacity of distributed photovoltaic power generation under the line, and the approved but not yet connected distributed photovoltaic power generation under the line from the electricity information collection system;

[0085] Step 2: Obtain the historical one-year line load profile curve from DMS, delete abnormal data, and obtain the minimum load;

[0086] Step 3: Calculate the minimum load rate of the line. The calculation formula is: Minimum load rate = Minimum load / Line rated capacity * 100%. According to the minimum load rate, the line load level is divided into no load, light load and heavy load, and different labels are used for different levels. At the same time, the heavy load line is highlighted.

[0087] Step 4: Obtain the access capacity of the power supply bus from the control cloud, calculate the access capacity of the line using the self-absorption algorithm and the relative safety algorithm respectively, and take the access capacity with the smaller result as the access capacity of the line.

[0088] The calculation of the available capacity of distribution transformers is performed under the premise of ensuring the safety and stability of the power grid during operation. It considers the current load of the distribution transformers, as well as the already connected and confirmed connected power sources, energy storage, and loads. The calculation is based on the premise that the connection of distributed power sources does not cause reverse overload in the transformer area, and that the power flow of the transformer area directly connected to the 10kV line is reversed. For example... Figure 3 As shown, the specific steps for calculating the capacity that a distribution transformer can be connected to are as follows:

[0089] Step 1: Obtain the rated capacity of the distribution transformer, the installed capacity of distributed photovoltaic power generation connected to the distribution transformer, and the approved but not yet connected distributed photovoltaic power generation capacity from the electricity information collection system.

[0090] Step 2: Obtain the historical one-year distribution transformer load profile curve from the electricity consumption information collection system, delete abnormal data, and obtain the minimum load;

[0091] Step 3: Calculate the minimum load rate of the distribution transformer. The calculation formula is: minimum load rate = minimum load / rated capacity of distribution transformer * 100%. According to the minimum load rate, the load level of the distribution transformer is divided into no load, light load and heavy load. Different labels are used for different levels, and the heavy load distribution transformer is highlighted.

[0092] Step 4: Based on the available capacity of the line to which the distribution transformer belongs, calculate the available capacity of the distribution transformer using the self-absorption algorithm and the relative safety algorithm respectively, and take the smaller available capacity as the available capacity of the distribution transformer.

[0093] The specific steps for calculating the line's accessible capacity and the distribution transformer's accessible capacity using the self-absorption algorithm and the relative safety algorithm are as follows: Figure 4 As shown:

[0094] The available capacity of the line is calculated once when the application starts, and then once every cycle according to the device's startup cycle. The specific calculation steps are as follows:

[0095] Step 1: Obtain the current carrying capacity of the incoming line switch;

[0096] Step 2: Obtain the installed capacity of distributed power sources that have been connected to the line, and obtain the installed capacity of distributed power sources that have been approved but not yet connected to the line.

[0097] Step 3, Historical Data Acquisition Rules: The data for the line is stored in a daily table. If the daily table exists, the data is retrieved; otherwise, it is skipped.

[0098] Step 4: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min ;

[0099] Step 5: Calculate the minimum equivalent load factor η min The current line's access capacity level is evaluated. The line level evaluation only considers the line's own load rate. The specific formula is as follows:

[0100] η min =P min / S e *100%

[0101] Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor η min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels.

[0102] Step 6: Calculate the line's connectable capacity using the self-absorption algorithm. The specific formula is as follows:

[0103] P ms =S e *(K r +η min )-P PF ;

[0104]

[0105] Where I is the current carrying capacity; P ms For the maximum capacity of newly added distributed power sources; K r The operating margin factor for the equipment is generally taken as 0.8 based on the assumption that the equipment is not under heavy load; P PF This refers to the installed capacity of distributed power sources that have been approved but not yet connected to the line, including the capacity of the distribution transformers connected to the line.

[0106] The line's access capacity is calculated using a relatively safe algorithm, with the specific formula as follows:

[0107] P ms =S e *0.8-P YJ -P PF ;

[0108] Among them, P YJ This refers to the installed capacity of distributed power sources already connected to the line, including the capacity of distribution transformers connected to the line.

[0109] The calculation of the available capacity of the distribution transformer will be performed once when the application starts, and then once a week thereafter. The specific calculation steps are as follows:

[0110] Step 1: Obtain the rated capacity of the distribution transformer;

[0111] Step 2: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min Obtain the installed capacity P of the distributed power sources connected to the distribution transformer. YJ The approved but not yet connected distributed power generation capacity P PF ;

[0112] Step 3: Calculate the minimum equivalent load factor η min To evaluate the current line's available capacity level, the transformer level evaluation considers both the transformer's load factor and the load factor of the line it connects to. The specific formula is as follows:

[0113] η min =P min / S e *100%

[0114] Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor η min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels.

[0115] Step 4: Calculate the available capacity of the distribution transformer using the self-absorption algorithm. The specific formula is as follows:

[0116] P ms =S e *(K r +η min )-P PF ;

[0117]

[0118] The capacity that can be connected to the distribution transformer is calculated using a relatively safe algorithm. The specific formula is as follows:

[0119] P ms =S e -P YJ -P PF .

[0120] Based on the minimum equivalent load rate η min The numerical values ​​are used to divide the accessibility level into three levels, and accessibility guidance is provided according to the level, as shown in Table 1.

[0121] Table 1 Accessibility Rating Table

[0122]

[0123] S2. Capacity Assessment: Based on the load rate of grid equipment after distributed power generation is connected, this assessment integrates information from the production management system and uses geographic maps and E-Charts charts to monitor the capacity indicators of power grid areas. The capacity assessment requires a comparison between the available capacity and the capacity to be connected. Figure 5 As shown, the specific content includes: selecting a relatively safe algorithm or a self-eliminating algorithm, obtaining the access capacity of the corresponding algorithm at the access location, and comparing it with the access capacity to be accessed in the current input parameters; depending on the comparison result, the following actions are performed respectively:

[0124] (1) If the current capacity to be connected is greater than the available capacity, then feedback is given that it cannot be connected, and other available locations are calculated and recommended. When the connection location is a distribution transformer, other locations under the same line that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended. When the connection location is a line, other locations under the same substation that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended.

[0125] (2) If the current capacity to be accessed is less than the available capacity, then the access is approved. At the same time, the minimum equivalent load rate after access is calculated and the evaluation level is determined.

[0126] Before connecting distributed power sources, the connection point and voltage level should be determined. When the connection location is a distribution transformer, other locations on the same line with a capacity greater than the current capacity to be connected are recommended. When the connection location is a line, other locations on the same substation with a capacity greater than the current capacity to be connected are recommended. The calculation scope of the carrying capacity assessment includes:

[0127] (1) If the distributed power source is connected to the low-voltage distribution network, the calculation scope is the area directly connected to the distribution transformer and the low-voltage line.

[0128] (2) If the distributed power source is connected to the medium voltage distribution network and is connected in a T-connection manner, the calculation scope is the public line connected to the distributed power source by the T-connection. When the line is back-feeding, the upstream main transformer should be further evaluated. If it is directly connected to the low voltage bus of the substation by a dedicated line, the calculation scope is the main transformer equipment connected to the distributed power source.

[0129] This invention also proposes a distribution network system accessibility capacity calculation and carrying capacity assessment system, including an accessibility capacity calculation module, a carrying capacity assessment module, and a computer program that can run on a processor. It should be noted that each module in the above system corresponds to a specific step of the method provided in this invention embodiment, possessing the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in this invention embodiment.

[0130] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for calculating the access capacity and assessing the carrying capacity of a distribution network system, characterized in that, Includes the following steps: S1. Accessible capacity calculation, including: using a geographic map to determine the accessible capacity of distribution transformers and 10kV lines around a specified location, and completing the accessible capacity calculation and accessibility level evaluation of the access equipment; specifically: S101. Obtain the corresponding capacity data of the line from the electricity consumption information collection system; S102. Obtain the historical one-year line load profile curve from the DMS system, delete abnormal data, and obtain the minimum load. S103. Calculate the minimum load rate of the line, divide the line into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavily loaded lines. S104. Obtain the available capacity of the power supply bus from the control cloud, calculate the available capacity of the line using both the self-absorption algorithm and the relative safety algorithm, and take the smaller available capacity as the available capacity of the line; specifically: Step 1: Obtain the current carrying capacity of the incoming line switch; Step 2: Obtain the installed capacity of distributed power sources that have been connected to the line, and obtain the installed capacity of distributed power sources that have been approved but not yet connected to the line. Step 3, Historical Data Acquisition Rules: The data for the line is stored in a daily table. If the daily table exists, the data is retrieved; otherwise, it is skipped. Step 4: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min ; Step 5: Calculate the minimum equivalent load factor. min The formula for evaluating the current access capacity level of the line is as follows: ŋ min =P min / S e *100%; Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor ŋ min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels. Step 6: Calculate the line's connectable capacity using the self-absorption algorithm. The specific formula is as follows: P ms =S e *(K r +ŋ min )-P PF ; S e = I*10* ; Where I is the current carrying capacity; P ms For the maximum capacity of newly added distributed power sources; K r The operating margin factor for the equipment is generally taken as 0.8 based on the assumption that the equipment is not under heavy load; P PF This refers to the installed capacity of distributed power sources that have been approved but not yet connected to the line, including the capacity of the distribution transformers connected to the line. The line's access capacity is calculated using a relatively safe algorithm, with the following formula: P ms = S e *0.8-P YJ -P PF ; Among them, P YJ This refers to the installed capacity of distributed power sources already connected to the line, including the capacity of distribution transformers connected to the line. S105. Obtain the corresponding capacity data of the distribution transformer from the electricity consumption information collection system; S106. Obtain the historical one-year distribution transformer load profile curve from the electricity consumption information collection system, delete abnormal data, and obtain the minimum load. S107. Calculate the minimum load rate of the distribution transformer, divide the line into load levels according to the minimum load rate, and mark them differently. At the same time, the heavily loaded distribution transformers are highlighted. S108. Based on the access capacity of the line to which the distribution transformer belongs in step S104, calculate the access capacity of the distribution transformer using the self-absorption algorithm and the relative safety algorithm respectively, and take the access capacity with the smaller result as the access capacity of the distribution transformer. S2. Carrying capacity assessment, including: using the load rate of grid equipment after the access of distributed power sources as the basic criterion, integrating the ledger information of the production management system, and monitoring the carrying capacity index of the power grid area based on geographical maps and E-Charts charts.

2. The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 1, characterized in that, The calculation of accessible capacity includes the calculation of accessible capacity for lines and distribution transformers, and the specific details are as follows: (1) Calculation of line access capacity: Under the premise of ensuring the safety and stability of the power grid in operation, the calculation is carried out in combination with the current load of the line and the power sources, energy storage and loads that have been connected and have been clearly connected. The calculation is based on the judgment that the connection of distributed power sources does not cause reverse overload of 10kV lines and the power flow of the line directly connected to the upstream main transformer is reversed. (2) Calculation of the capacity that can be connected to the distribution transformer: Under the premise of ensuring the safety and stability of the power grid in operation, the calculation is carried out in combination with the current load of the distribution transformer and the power supply, energy storage and load that have been connected and have been clearly connected. The calculation is based on the judgment that the connection of the distributed power supply does not cause the transformer area to be overloaded in reverse and the power flow of the transformer area directly connected to the 10kV line is reversed.

3. The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 1, characterized in that, In step S103, the formula for calculating the minimum load rate is: minimum load rate = minimum load / rated capacity of distribution transformer * 100%; and the load is divided into three levels: no load, light load and heavy load according to the minimum load rate.

4. The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 1, characterized in that, In step S108, the calculation steps for the available capacity of the distribution transformer are as follows: Step 1: Obtain the rated capacity of the distribution transformer; Step 2: Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min Obtain the installed capacity P of the distributed power sources connected to the distribution transformer. YJ The approved but not yet connected distributed power generation capacity P PF ; Step 3: Calculate the minimum equivalent load factor. min The formula for evaluating the current access capacity level of the line is as follows: ŋ min =P min / S e *100%; Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor ŋ min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels. Step 4: Calculate the available capacity of the distribution transformer using the self-absorption algorithm. The specific formula is as follows: P ms =S e *(K r +ŋ min )-P PF ; S e = I*10* ; The available capacity of distribution transformers is calculated using a relatively safe algorithm, and the specific formula is as follows: P ms = S e -P YJ -P PF 。 5. The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 1, characterized in that, In step S2, the load-bearing capacity assessment should be conducted before connecting distributed power sources. The connection point and voltage level should be determined first. The calculation scope of the load-bearing capacity assessment includes: (1) If the distributed power source is connected to the low-voltage distribution network, the calculation scope is the distribution area and low-voltage line directly connected to the distributed power source; (2) If the distributed power source is connected to the medium voltage distribution network and is connected in a T-connection manner, the calculation scope is the public line connected to the distributed power source by T. When the line is back-feeding, the upstream main transformer should be further evaluated. If it is directly connected to the low voltage bus of the substation by a dedicated line, the calculation scope is the main transformer equipment connected to the distributed power source.

6. The method for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 1, characterized in that, The specific contents of the bearing capacity assessment in step S2 include: S201. Select either a relatively safe algorithm or a self-absorption algorithm to calculate the corresponding accessible capacity; S202. Obtain the access capacity of the corresponding algorithm of the access location and compare it with the access capacity of the current input parameter. S203. Based on the different comparison results, perform the following actions respectively: (1) If the current capacity to be connected is greater than the available capacity, then feedback is given that it cannot be connected, and other available locations are calculated and recommended. When the connection location is a distribution transformer, other locations under the same line that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended. When the connection location is a line, other locations under the same substation that meet the requirement that the available capacity is greater than the current capacity to be connected are recommended. (2) If the current capacity to be accessed is less than the available capacity, then the access is allowed. At the same time, the minimum equivalent load rate after access is calculated and the evaluation level is determined.

7. A system applied to the method for calculating the access capacity and assessing the carrying capacity of a distribution network system as described in claim 1, characterized in that, include: The access capacity calculation module includes a line access capacity calculation module and a distribution transformer access capacity calculation module. It is used to study the access capacity of distribution transformers and 10kV lines around a specified location based on the access capacity data of distribution transformers and 10kV lines, combined with a geographic map, and to complete the equipment access capacity calculation and accessibility level evaluation. The carrying capacity assessment module is used to determine the load rate of grid equipment after the access of distributed power sources as the basic criterion. It integrates the ledger information of the production management system and realizes the monitoring of regional carrying capacity indicators based on geographic maps and E-Charts charts.

8. The system for calculating the access capacity and assessing the carrying capacity of a distribution network system according to claim 7, characterized in that, It can be connected to a capacity calculation module, specifically configured to perform the following steps: Step 1: Obtain the corresponding capacity data of the line from the electricity information collection system; Step 2: Obtain the historical one-year line load profile curve from the DMS system, delete abnormal data, and obtain the minimum load; Step 3: Calculate the minimum load rate of the line, classify the lines into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavily loaded lines. Step 4: Obtain the available capacity of the power supply bus from the control cloud, and calculate the available capacity of the line using both the self-absorption algorithm and the relative safety algorithm. The smaller available capacity is the available capacity of the line. Specifically: (1) Obtain the current carrying capacity of the incoming line switch; (2) Obtain the installed capacity of distributed power sources that have been connected to the line and obtain the installed capacity of distributed power sources that have been approved but not yet connected to the line. (3) Historical data acquisition rules: The data of the line is stored in a daily table. If the daily table exists, it will be acquired; otherwise, it will be skipped. (4) Based on the configuration information, obtain the historical minimum power generation P within one year with an absolute value greater than 1. min ; (5) Calculate the minimum equivalent load factor ŋ min The formula for evaluating the current access capacity level of the line is as follows: ŋ min =P min / S e *100%; Among them, S e The rated apparent power can be obtained from the electricity consumption information collection system; based on the minimum equivalent load factor ŋ min Access levels are divided into three categories: secure access, access warning, and access restriction. Access guidance is provided based on these levels. (6) The line's connectable capacity is calculated using the self-absorption algorithm. The specific formula is as follows: P ms =S e *(K r +ŋ min )-P PF ; S e = I*10* ; Where I is the current carrying capacity; P ms For the maximum capacity of newly added distributed power sources; K r The operating margin factor for the equipment is generally taken as 0.8 based on the assumption that the equipment is not under heavy load; P PF This refers to the installed capacity of distributed power sources that have been approved but not yet connected to the line, including the capacity of the distribution transformers connected to the line. The line's access capacity is calculated using a relatively safe algorithm, with the following formula: P ms = S e *0.8-P YJ -P PF ; Among them, P YJ This refers to the installed capacity of distributed power sources already connected to the line, including the capacity of distribution transformers connected to the line. Step 5: Obtain the corresponding capacity data of the distribution transformer from the electricity consumption information collection system; Step 6: Obtain the historical one-year distribution transformer load profile curve from the electricity consumption information collection system, delete abnormal data, and obtain the minimum load; Step 7: Calculate the minimum load rate of the distribution transformer, classify the line into load levels according to the minimum load rate, and mark them differently. At the same time, highlight the heavy load distribution transformer. Step 8: Based on the access capacity of the line to which the distribution transformer belongs in Step 4, calculate the access capacity of the distribution transformer using the self-absorption algorithm and the relative safety algorithm respectively. The smaller access capacity is the access capacity of the distribution transformer. The carrying capacity assessment module is specifically configured to perform the following actions: select a relatively safe algorithm or a self-absorption algorithm, obtain the access capacity of the corresponding algorithm at the access location, and compare it with the capacity to be accessed in the current input parameters; depending on the comparison result, perform the following operations respectively: (1) If the current capacity to be accessed is greater than the available capacity, then feedback is given that access is not possible, and other available access locations are calculated and recommended. (2) If the current capacity to be accessed is less than the available capacity, then the access is allowed. At the same time, the minimum equivalent load rate after access is calculated and the evaluation level is determined.

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