A method and device for selecting a grid-connected scheme for distributed power sources

Abstract

The present invention discloses a method and device for selecting a grid-connected scheme for a distributed power source. The method comprises: in response to an input grid-connected request, obtaining basic equipment data and a plurality of grid-connected schemes carried in the grid-connected request; calculating a plurality of evaluation indicators corresponding to each grid-connected scheme according to the basic equipment data, and constructing an evaluation indicator matrix using the plurality of evaluation indicators; selecting the optimal indicator in the evaluation indicator matrix and constructing an optimal indicator matrix; calculating a correlation coefficient according to the evaluation indicator matrix and the optimal indicator matrix, and generating a correlation matrix using the correlation coefficient; determining and outputting a target grid-connected scheme based on a preset weight coefficient matrix and the correlation matrix, thereby more efficiently and accurately selecting a grid-connected scheme for a distributed power source.

Description

Technical Field

[0001] The present invention relates to the technical field, and in particular to a method and device for selecting a grid-connected scheme for a distributed power source. Background Art

[0002] Distributed generation (DGs), a clean and sustainable energy source, has been widely used in power generation in distribution networks, providing a solution to the challenges of fossil fuel depletion and environmental pollution. However, the intermittent and random nature of DG output impacts system power flow, transients, and fault analysis, potentially threatening the safe and stable operation of the power grid. Furthermore, the system's operational efficiency and economic benefits are closely related to the location and access capacity of DGs. Therefore, reliability analysis and comprehensive evaluation of distribution networks with high DG penetration are essential.

[0003] To this end, existing technologies employ comprehensive assessments to objectively, impartially, and rationally evaluate distribution networks based on current operating conditions and historical data. For example, assessment methods based on the Markov algorithm and the DARE-RSR algorithm exist. The Markov-based distribution network reliability assessment method establishes a distribution network stability assessment model and calculates the stability of a distribution network containing distributed generation (DGs). The DARE-RSR-based comprehensive assessment model is simple and practical, and can guide microgrid operations.

[0004] However, the above method does not take into account the stability analysis of the system and other aspects of the marketing of the grid-connected scheme of distributed power sources in the distribution network, cannot meet the N-1 safety verification, and it is difficult to efficiently and accurately select the grid-connected scheme adopted by distributed power sources in the distribution network. Summary of the Invention

[0005] The present invention provides a method and device for selecting a grid-connected scheme for distributed power sources, which solves the technical problems that the existing technology does not consider the stability analysis of the system and other aspects of the marketing of the grid-connected scheme of distributed power sources in the distribution network, cannot meet the N-1 safety verification, and is difficult to efficiently and accurately select the grid-connected scheme adopted by the distributed power sources in the distribution network.

[0006] The present invention provides a method for selecting a grid-connected scheme for a distributed power source, comprising:

[0007] In response to an input grid connection request, obtaining basic device data and a plurality of grid connection schemes carried in the grid connection request;

[0008] Calculating multiple evaluation indicators corresponding to each of the grid-connected schemes based on the equipment basic data, and constructing an evaluation indicator matrix using the multiple evaluation indicators;

[0009] Selecting the optimal indicator in the evaluation indicator matrix to construct an optimal indicator matrix;

[0010] Calculating correlation coefficients based on the evaluation index matrix and the optimal index matrix, and generating a correlation matrix using the correlation coefficients;

[0011] Based on the preset weight coefficient matrix and the correlation matrix, a target grid connection scheme is determined and output.

[0012] Optionally, the evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; the step of calculating the multiple evaluation indicators corresponding to each of the grid-connected schemes based on the equipment basic data, and constructing an evaluation indicator matrix using the multiple evaluation indicators includes:

[0013] extracting transformer rated capacity, transformer transfer load, transformer load factor and tie line capacity from the equipment basic data;

[0014] Calculating the safety and stability evaluation index according to the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer and the capacity of the tie line;

[0015] Determining the plurality of distribution network evaluation indicators based on the equipment basic data;

[0016] An evaluation index matrix is ​​constructed using the safety and stability evaluation index and the multiple distribution network evaluation indexes.

[0017] Optionally, the step of calculating the safety and stability evaluation index according to the rated capacity of the transformer, the transformer transfer load, the transformer load rate and the tie line capacity includes:

[0018] Determining whether each of the grid-connected schemes meets preset constraints based on the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line;

[0019] If the conditions are met, the safety and stability evaluation index is calculated using the transformer rated capacity and the transformer load rate in combination with the safety margin calculation formula;

[0020] If not satisfied, the grid connection plan is deleted;

[0021] The constraints are:

[0022]

[0023] Among them, Ω DSSR is the set of all transformers, R i 、R j are the rated capacity of transformer i and transformer j respectively, B ijis the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, C ij is the capacity of the tie line between transformer i and transformer j, G is the preset lower limit of load, T i 、T j are the transformer load factors of transformer i and transformer j respectively;

[0024] The safety margin calculation formula is:

[0025]

[0026] Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

[0027] Optionally, the step of calculating a correlation coefficient based on the evaluation index matrix and the optimal index matrix, and using the correlation coefficient to generate a correlation matrix includes:

[0028] Performing normalization preprocessing on the evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix according to a preset normalization formula to obtain a normalized matrix;

[0029] Calculate the correlation coefficient between each evaluation indicator and the corresponding optimal indicator in the normalized matrix using a preset correlation coefficient calculation formula;

[0030] According to each of the grid connection schemes as a group, sorting the correlation coefficients to generate a correlation matrix;

[0031] The normalization formula is:

[0032]

[0033] Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the k-th evaluation indicator; is the maximum value of the kth evaluation indicator;

[0034] The correlation coefficient calculation formula is:

[0035]

[0036] Among them, i(k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid connection scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

[0037] Optionally, the step of determining and outputting a target grid connection scheme based on a preset weight coefficient matrix and the correlation matrix includes:

[0038] Extracting a correlation submatrix corresponding to each grid connection scheme from the correlation matrix;

[0039] Using a preset weight coefficient matrix and each of the correlation degree sub-matrices, respectively calculating the comprehensive correlation degree corresponding to each of the grid connection schemes;

[0040] All the grid-connected schemes are sorted from high to low according to the comprehensive correlation, and the grid-connected scheme with the highest comprehensive correlation is selected as the target grid-connected scheme and output.

[0041] The present invention also provides a distributed power supply grid connection scheme selection device, comprising:

[0042] A data acquisition module, configured to respond to an input grid connection request and acquire basic device data and a plurality of grid connection schemes carried in the grid connection request;

[0043] An evaluation index matrix construction module is used to calculate a plurality of evaluation indicators corresponding to each of the grid-connected schemes according to the equipment basic data, and to construct an evaluation index matrix using the plurality of evaluation indicators;

[0044] An optimal indicator matrix construction module is used to select the optimal indicator in the evaluation indicator matrix and construct the optimal indicator matrix;

[0045] A correlation matrix generation module is used to calculate the correlation coefficient based on the evaluation index matrix and the optimal index matrix, and generate a correlation matrix using the correlation coefficient;

[0046] The target grid connection scheme determination module is used to determine and output the target grid connection scheme based on a preset weight coefficient matrix and the correlation matrix.

[0047] Optionally, the evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; the evaluation indicator matrix construction module includes:

[0048] A data extraction submodule, configured to extract transformer rated capacity, transformer transfer load, transformer load rate, and tie line capacity from the equipment basic data;

[0049] A safety and stability evaluation index calculation submodule, configured to calculate the safety and stability evaluation index according to the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line;

[0050] A distribution network evaluation index calculation submodule, configured to determine the plurality of distribution network evaluation indicators based on the equipment basic data;

[0051] The evaluation index matrix construction submodule is used to construct an evaluation index matrix using the safety and stability evaluation index and the multiple distribution network evaluation indicators.

[0052] Optionally, the safety and stability evaluation index calculation submodule is specifically used to:

[0053] Determining whether each of the grid-connected schemes meets preset constraints based on the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line;

[0054] If the conditions are met, the safety and stability evaluation index is calculated using the transformer rated capacity and the transformer load rate in combination with the safety margin calculation formula;

[0055] If not satisfied, the grid connection plan is deleted;

[0056] The constraints are:

[0057]

[0058] Among them, Ω DSSR is the set of all transformers, R i 、R j are the rated capacity of transformer i and transformer j respectively, B ij is the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, C ij is the capacity of the tie line between transformer i and transformer j, G is the preset lower limit of load, T i 、T j are the transformer load factors of transformer i and transformer j respectively;

[0059] The safety margin calculation formula is:

[0060]

[0061] Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

[0062] Optionally, the correlation matrix generation module includes:

[0063] A matrix normalization submodule is used to perform normalization preprocessing on the evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix according to a preset normalization formula to obtain a normalized matrix;

[0064] A correlation coefficient calculation submodule is used to calculate the correlation coefficient between each evaluation indicator and the corresponding optimal indicator in the normalized matrix using a preset correlation coefficient calculation formula;

[0065] A correlation ranking submodule is used to group the grid-connected schemes and sort the correlation coefficients to generate a correlation matrix;

[0066] The normalization formula is:

[0067]

[0068] Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the k-th evaluation indicator; is the maximum value of the kth evaluation indicator;

[0069] The correlation coefficient calculation formula is:

[0070]

[0071] Among them, i (k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid connection scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

[0072] Optionally, the target grid connection solution determination module includes:

[0073] A correlation degree sub-matrix extraction sub-module, configured to extract a correlation degree sub-matrix corresponding to each grid connection scheme from the correlation degree matrix;

[0074] A comprehensive correlation calculation submodule, configured to calculate the comprehensive correlation corresponding to each of the grid-connected schemes using a preset weight coefficient matrix and each of the correlation sub-matrices;

[0075] The scheme sorting submodule is used to sort all the grid-connected schemes from high to low according to the comprehensive correlation, select the grid-connected scheme with the highest comprehensive correlation as the target grid-connected scheme and output it.

[0076] It can be seen from the above technical solutions that the present invention has the following advantages:

[0077] The present invention responds to a grid connection request input by a user, obtains the basic device data and multiple grid connection schemes carried in the grid connection request, calculates multiple evaluation indicators corresponding to each grid connection scheme based on the basic device data and the settings within each grid connection scheme, and uses these to construct an evaluation indicator matrix; at the same time, selects various optimal indicators in the evaluation indicator matrix to construct a corresponding optimal indicator matrix; then, based on the evaluation indicator matrix and the optimal indicator matrix, calculates the correlation coefficient between each evaluation indicator and the optimal indicator of each grid connection scheme, and uses the correlation coefficient to construct a correlation matrix; finally, the correlation matrix is ​​divided into groups based on the grid connection scheme, and combined with a preset weight coefficient matrix, the comprehensive correlation of each grid connection scheme is calculated, and the grid connection scheme with the highest comprehensive correlation is selected as the target grid connection scheme for output. This solves the technical problems of the prior art that the marketing of distributed power supply grid connection schemes in the distribution network does not consider system stability analysis and other aspects, cannot meet N-1 safety verification, and is difficult to efficiently and accurately select the grid connection scheme adopted by the distributed power supply in the distribution network, and more efficiently and accurately selects the grid connection scheme of the distributed power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0079] Figure 1 A flowchart of the steps of a method for selecting a grid-connected solution for a distributed power source provided in the first embodiment of the present invention;

[0080] Figure 2 A flowchart of the steps of a method for selecting a grid-connected solution for a distributed power source provided in the second embodiment of the present invention;

[0081] Figure 3 This is an indicator system diagram of various distribution network evaluation indicators according to an embodiment of the present invention;

[0082] Figure 4 A topological diagram of a distribution network system provided by an embodiment of the present invention;

[0083] Figure 5 This is a structural block diagram of a distributed power supply grid connection scheme selection device provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0084] The embodiments of the present invention provide a method and device for selecting a grid-connected scheme for distributed power sources, which are used to solve the technical problems that the existing technology does not consider the stability analysis of the system and other aspects of the marketing of the grid-connected scheme of distributed power sources in the distribution network, cannot meet the N-1 safety verification, and is difficult to efficiently and accurately select the grid-connected scheme adopted by the distributed power sources in the distribution network.

[0085] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0086] See also Figure 1 , Figure 1 This is a flowchart of the steps of a method for selecting a grid-connected solution for a distributed power source provided in the first embodiment of the present invention.

[0087] The present invention provides a method for selecting a grid-connected scheme for a distributed power source, comprising the following steps:

[0088] Step 101: In response to an input grid connection request, obtain basic device data and multiple grid connection plans carried in the grid connection request;

[0089] The grid connection scheme in the embodiment of the present invention refers to a data scheme including but not limited to the model of the distributed power source, the grid connection bus, the access capacity, the location, the number of power sources and the actual output.

[0090] In an embodiment of the present invention, when a grid connection request input by a user is received, indicating that the user needs to connect at least one distributed power source to the current distribution network, the basic data of the equipment carried and the data plan pre-planned by the user for the grid connection request can be obtained from the grid connection request to provide a data comparison basis for subsequent grid connection plans.

[0091] Step 102: Calculate multiple evaluation indicators corresponding to each grid connection scheme based on the basic equipment data, and construct an evaluation indicator matrix using the multiple evaluation indicators.

[0092] After obtaining the basic equipment data, since the selection of the grid-connected scheme needs to be evaluated from multiple angles, the various evaluation indicators corresponding to each grid-connected scheme can be calculated based on the basic equipment data. Then, the corresponding multiple evaluation indicators can be sorted according to the grid-connected scheme to construct an evaluation indicator matrix including all grid-connected schemes.

[0093] It should be noted that the evaluation indicators may include but are not limited to calculations from four aspects: safety, economy, power supply quality and development coordination. The safety aspect may include N-1 safe and stable distance, line fault outage rate, transformer fault outage rate, "low voltage" occurrence rate and distributed power outage rate; the economy aspect may include network loss rate, distributed power generation cost rate, distributed power life degradation rate, distributed power economic benefit rate and distributed power construction cycle; power supply quality may include system voltage deviation rate, distributed power power fluctuation rate, three-phase imbalance rate, voltage harmonic distortion rate and system voltage flicker rate; development coordination may include distributed power capacity proportion, new energy capacity proportion, electric locomotive capacity proportion and energy conservation and emission reduction capabilities.

[0094] Step 103, selecting the optimal indicator in the evaluation indicator matrix and constructing the optimal indicator matrix;

[0095] After obtaining the evaluation indicator matrix, the optimal value of each evaluation indicator can be selected as the optimal indicator according to the type of evaluation indicator, and the optimal indicator matrix can be constructed with each optimal indicator.

[0096] Step 104, calculating the correlation coefficient based on the evaluation index matrix and the optimal index matrix, and using the correlation coefficient to generate a correlation matrix;

[0097] In an embodiment of the present invention, after obtaining the evaluation index matrix and the optimal index matrix, further normalization processing can be performed based on the above two matrices to unify the dimensions of various evaluation indicators or optimal indicators in the matrix to facilitate subsequent comparison.

[0098] After normalization preprocessing, the normalized evaluation index matrix and the optimal index matrix are used to calculate the correlation coefficients between the evaluation index sequence corresponding to each grid-connected scheme and the optimal index matrix, and all the calculated correlation coefficients are arranged in the form of a matrix to generate a correlation matrix.

[0099] Step 105: Based on the preset weight coefficient matrix and correlation matrix, a target grid connection scheme is determined and output.

[0100] In the specific implementation, after obtaining the correlation matrix corresponding to all grid-connected schemes, the correlation sequence corresponding to the grid-connected schemes can be extracted from it, and the preset weight coefficient matrix and the correlation sequence are used for calculation to determine the comprehensive correlation corresponding to each grid-connected scheme, and the grid-connected scheme with the highest comprehensive correlation is selected as the target grid-connected scheme for output.

[0101] In an embodiment of the present invention, in response to a grid connection request input by a user, basic device data and multiple grid connection schemes carried in the grid connection request are obtained from the grid connection request. Then, based on the basic device data and in combination with the settings within each grid connection scheme, multiple evaluation indicators corresponding to each grid connection scheme are calculated, and an evaluation indicator matrix is ​​constructed using the corresponding evaluation indicators. At the same time, various optimal indicators in the evaluation indicator matrix are selected to construct a corresponding optimal indicator matrix. Then, based on the evaluation indicator matrix and the optimal indicator matrix, the correlation coefficient between each evaluation indicator and the optimal indicator of each grid connection scheme is calculated, and a correlation matrix is ​​constructed using the correlation coefficient. Finally, the correlation matrix is ​​divided into groups based on the grid connection schemes. In combination with a preset weight coefficient matrix, the comprehensive correlation of each grid connection scheme is calculated, and the grid connection scheme with the highest comprehensive correlation is selected as the target grid connection scheme for output. This solves the technical problems that the prior art does not consider system stability analysis and other aspects of the marketing of distributed power supply grid connection schemes in the distribution network, cannot meet N-1 safety verification, and is difficult to efficiently and accurately select the grid connection scheme adopted by the distributed power supply in the distribution network. The grid connection scheme of the distributed power supply is selected more efficiently and accurately.

[0102] See also Figure 2 , Figure 2 This is a flowchart of the steps of a method for selecting a grid-connected solution for a distributed power source provided in the second embodiment of the present invention.

[0103] The present invention provides a method for selecting a grid-connected scheme for a distributed power source, wherein the evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; the method comprises the following steps:

[0104] Step 201, in response to an input grid connection request, obtain basic equipment data and multiple grid connection schemes carried in the grid connection request; the grid connection scheme in the embodiment of the present invention refers to a data scheme including but not limited to the model of the distributed power source, the grid connection bus, the access capacity, the location, the number of power sources and the actual output.

[0105] In an embodiment of the present invention, when a grid connection request input by a user is received, indicating that the user needs to connect at least one distributed power source to the current distribution network, the basic data of the equipment carried and the data plan pre-planned by the user for the grid connection request can be obtained from the grid connection request to provide a data comparison basis for subsequent grid connection plans.

[0106] Step 202: extracting transformer rated capacity, transformer transfer load, transformer load rate, and tie line capacity from equipment basic data;

[0107] In an embodiment of the present invention, in order to obtain the data basis for the subsequent calculation of safety and stability evaluation indicators, the corresponding transformer rated capacity, transformer transfer load, and transformer load rate tie line capacity in the original distribution network can be extracted from the equipment basic data to facilitate the subsequent evaluation of the distributed power supply grid connection plan.

[0108] It should be noted that the basic equipment data not only includes the above data, but also may include but is not limited to: basic equipment parameters of distribution network transmission lines, main transformers, distribution transformers, loads, circuit breakers, switches, system topology information, node voltages, branch currents, historical data of actual operating power of loads, and basic parameters of distributed power supply equipment to be connected to the grid.

[0109] Step 203, calculating a safety and stability evaluation index based on the transformer rated capacity, transformer transfer load, transformer load factor, and tie line capacity;

[0110] The safety and stability evaluation index in the real-time example of the present invention refers to the N-1 safety and stability distance. Among them, the N-1 safety and stability evaluation is the basis for the planning and operation of the distribution system. The definition of this criterion can be summarized as follows: when a device fails, the load is transferred so that the main transformer and feeder are not overloaded, and all loads except the fault section are powered.

[0111] Optionally, step 203 may include the following sub-steps: judging whether each grid connection scheme meets preset constraint conditions based on the transformer rated capacity, transformer transfer load, transformer load rate, and tie line capacity; if so, calculating the safety and stability evaluation index using the transformer rated capacity and transformer load rate in combination with a safety margin calculation formula; if not, deleting the grid connection scheme;

[0112] In one example of the present invention, the transformer rated capacity, transformer transfer load, transformer load rate and tie line capacity are substituted into the preset constraints to determine whether the grid-connected scheme meets the requirements. If so, the transformer rated capacity and transformer load rate are further used, combined with the safety margin calculation formula, to calculate the safety and stability evaluation index. If not, the grid-connected scheme is deleted to achieve preliminary screening of inappropriate grid-connected schemes.

[0113] The constraints are:

[0114]

[0115] Among them, Ω DSSR is the set of all transformers, R i 、R j are the rated capacity of transformer i and transformer j respectively, B ij is the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, Cij is the capacity of the tie line between transformer i and transformer j, G is the preset lower limit of load, T i 、T j are the transformer load factors of transformer i and transformer j respectively;

[0116] In specific implementation, the above constraints can be simplified as follows:

[0117]

[0118] Among them, B i is the i-th boundary of the security domain; U i is the contact unit, and transformer i is the contact center.

[0119] The safety margin calculation formula is:

[0120]

[0121] Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

[0122] In specific implementation, the safety and stability of the distribution system can be reflected by its location within the safety zone. If the system is located within the safety zone, it can be proved that the system's operating characteristics are safe and stable. Moreover, the farther away from the safety zone boundary, the better the safety and stability. At this time, the safety margin calculation formula can be used to calculate the safety distance of each transformer i. If the safety distance D i If the value is positive, the system is within the safe region. Otherwise, the system is unsafe and unstable. Safety margin can be used as an important indicator in a comprehensive evaluation model to assess the safety and stability of distribution networks containing distributed generation.

[0123] Step 204: determining a plurality of distribution network evaluation indicators based on the basic equipment data;

[0124] See also Figure 3 , Figure 3 An indicator system diagram of various distribution network evaluation indicators according to an embodiment of the present invention is shown.

[0125] In an embodiment of the present invention, after the basic equipment data is acquired, various distribution network evaluation indicators can be calculated based on the basic equipment data in combination with existing indicator calculation methods.

[0126] A variety of distribution network evaluation indicators can be calculated using power flow calculation and electromagnetic transient simulation algorithms to obtain relevant values ​​in different distributed power grid connection schemes, including: N-1 safe and stable distance, line fault outage rate, transformer fault outage rate, "low voltage" occurrence rate, distributed power outage rate, network loss rate, distributed power generation cost rate, distributed power life degradation rate, distributed power economic benefit rate, distributed power construction period, system voltage deviation rate, distributed power power fluctuation rate, three-phase imbalance rate, voltage harmonic distortion rate, system voltage flicker rate, distributed power capacity ratio, new energy capacity ratio, electric locomotive capacity ratio and energy conservation and emission reduction capabilities.

[0127] Power flow calculation is a term in electrical engineering that refers to the calculation of active power, reactive power, and voltage distribution within a power grid, given the power system's network topology, component parameters, and generation and load parameters. Power flow calculation determines the steady-state operating parameters of each component of the power system, based on the given grid structure and parameters and the operating conditions of components such as generators and loads. Typically, the given operating conditions include the power at each source and load point in the system, the voltage at the hub, and the voltage and phase angle at the equilibrium point. The operating parameters to be determined include the voltage amplitude and phase angle at each busbar node, the power distribution of each branch, and the power loss of the network.

[0128] Step 205: constructing an evaluation index matrix using safety and stability evaluation indicators and multiple distribution network evaluation indicators;

[0129] In one example of the present invention, after calculating the safety and stability evaluation index corresponding to each grid connection scheme, the sequence [X 11 X 21 X 31 X 41 ... X n1 ], and a variety of distribution network evaluation indicators are combined to construct an evaluation indicator matrix.

[0130] Specifically, the evaluation index matrix can be expressed as follows:

[0131]

[0132] Among them, X nm is the evaluation index, n is the number of solutions, and m is the number of evaluation indicators.

[0133] Step 206, selecting the optimal indicator in the evaluation indicator matrix and constructing the optimal indicator matrix;

[0134] After obtaining the evaluation index matrix, the optimal value is extracted from each evaluation index in the evaluation index matrix as the optimal index, and the optimal index is used to sort the evaluation indexes according to their types to construct the optimal index matrix.

[0135] In the specific implementation, the optimal indicator matrix can be expressed as:

[0136] X 0k =X 01 X 02 ... X 0m

[0137] Among them, X 0m is the mth evaluation indicator sequence X in the evaluation indicator matrix 1m X 2m ... X nm T The optimal value of .

[0138] Step 207, calculating the correlation coefficient based on the evaluation index matrix and the optimal index matrix, and using the correlation coefficient to generate a correlation matrix;

[0139] Optionally, step 207 may include the following sub-steps:

[0140] The evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix are normalized and preprocessed according to a preset normalization formula to obtain a normalized matrix; the correlation coefficient between each evaluation indicator in the normalized matrix and the corresponding optimal indicator is calculated using a preset correlation coefficient calculation formula;

[0141] According to the grid connection schemes as groups, the correlation coefficients are sorted to generate a correlation matrix;

[0142] In an embodiment of the present invention, since the evaluation indicators have different dimensions and cannot be directly compared, the original evaluation indicators and the optimal indicators can be pre-processed to obtain a normalized matrix. Then, combined with the correlation coefficient calculation formula, the correlation coefficient between each evaluation indicator and the optimal indicator in the normalized matrix is ​​calculated. Finally, the correlation coefficients are sorted according to the grid-connected schemes as groups to generate a correlation matrix.

[0143] The normalization formula is:

[0144]

[0145] Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the kth evaluation indicator; is the maximum value of the kth evaluation indicator;

[0146] In one example of the present invention, the normalized matrix can be expressed as:

[0147]

[0148] Among them, λ 01 λ 02 ...λ 0m Represents the optimal indicator matrix X 0m The rest are the normative values ​​of the evaluation index matrix.

[0149] The correlation coefficient calculation formula is:

[0150]

[0151] Among them, i (k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid-connected scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

[0152] In the embodiment of the present invention, the correlation matrix can be expressed by the following formula:

[0153]

[0154] Among them, n (m) is the correlation coefficient between the nth evaluation index and the nth optimal index of the mth grid-connected scheme.

[0155] Step 208: Based on the preset weight coefficient matrix and correlation matrix, determine and output the target grid connection plan.

[0156] Optionally, step 208 may include the following sub-steps: extracting a correlation sub-matrix corresponding to each grid-connected scheme from the correlation matrix; using a preset weight coefficient matrix and each correlation sub-matrix to calculate the comprehensive correlation corresponding to each grid-connected scheme; sorting all grid-connected schemes from high to low according to the comprehensive correlation, selecting the grid-connected scheme with the highest comprehensive correlation as the target grid-connected scheme and outputting it.

[0157] In one example of the present invention, after the correlation matrix is ​​calculated, the correlation submatrix corresponding to each grid connection scheme can be extracted therefrom. Then, the weight coefficient matrix and each correlation submatrix are used to calculate the comprehensive correlation of each parallel connection scheme after integrating all evaluation indicators. The specific calculation process can be as follows:

[0158]

[0159] Among them, r i is the comprehensive correlation of grid-connected scheme i, P im is the weight coefficient corresponding to the mth evaluation index of the i-th grid connection scheme in the weight coefficient matrix, ζ i(m) is the correlation coefficient of the mth evaluation indicator of grid connection scheme i.

[0160] After calculating the comprehensive correlations, the grid-connected schemes can be sorted from high to low according to the comprehensive correlations, and the grid-connected scheme with the highest comprehensive correlation can be selected as the target grid-connected scheme and output.

[0161] See also Figure 4 , Figure 4 A topological diagram of a distribution network system in an embodiment of the present invention is shown.

[0162] In the embodiment of the present invention, the main transformer and feeder parameters are shown in Table 1 and Table 2:

[0163]

[0164] Table 1 Main transformer parameters

[0165]

[0166] Table 2 Feeder parameters

[0167] There are four distributed generation grid connection schemes in this test case. The location and access capacity of distributed generation in different schemes are shown in Table 3:

[0168]

[0169] Table 3 Different grid connection schemes

[0170] In this example, when the load rate of the main transformer is 0.5, the N-1 safety distances of the four schemes are shown in Table 4:

[0171] plan Safety distance / m No DGs 0.4022 A 0.4091 B 0.4097 C 0.4110 D 0.4170

[0172] Table 4 Safety distances for different grid connection schemes

[0173] From Table 4, it can be concluded that the system safety distance increases with the grid connection of distributed generation, and scheme D has the best N-1 safety. The weight coefficients of the evaluation index system are obtained using the hierarchical analysis method, as shown in Table 5.

[0174] Evaluation Metrics Weight coefficient Evaluation Metrics Weight coefficient S1 0.4 P9 0.2482 S2 0.2 P10 0.1458 S3 0.3 P11 0.2 S4 0.1 P12 0.2 P1 0.4 P13 0.2 P2 0.15 P14 0.2 P3 0.2 P15 0.2 P4 0.1 P16 0.227 P5 0.15 P17 0.227 P6 0.2482 P18 0.1223 P7 0.2482 P19 0.4236 P8 0.1097

[0175] Table 5 Weight coefficients of different grid connection schemes

[0176] The comprehensive evaluation results of the test scheme are calculated by the hierarchical analysis method and the correlation analysis method based on the weight coefficient and the relationship coefficient matrix, as shown in Table 6.

[0177]

[0178]

[0179] Table 6 Correlation of different grid connection schemes

[0180] The evaluation results show that: Plan D has the best safety; Plan C has the best economy and power supply quality; Plan D has the best development coordination; Plan C has the best comprehensive evaluation, so Plan C is selected as the target grid-connected plan for distributed power sources.

[0181] In an embodiment of the present invention, in response to a grid connection request input by a user, basic device data and multiple grid connection schemes carried in the grid connection request are obtained from the grid connection request. Then, based on the basic device data and in combination with the settings within each grid connection scheme, multiple evaluation indicators corresponding to each grid connection scheme are calculated, and an evaluation indicator matrix is ​​constructed using the corresponding evaluation indicators. At the same time, various optimal indicators in the evaluation indicator matrix are selected to construct a corresponding optimal indicator matrix. Then, based on the evaluation indicator matrix and the optimal indicator matrix, the correlation coefficient between each evaluation indicator and the optimal indicator of each grid connection scheme is calculated, and a correlation matrix is ​​constructed using the correlation coefficient. Finally, the correlation matrix is ​​divided into groups based on the grid connection schemes. In combination with a preset weight coefficient matrix, the comprehensive correlation of each grid connection scheme is calculated, and the grid connection scheme with the highest comprehensive correlation is selected as the target grid connection scheme for output. This solves the technical problems that the prior art does not consider system stability analysis and other aspects of the marketing of distributed power supply grid connection schemes in the distribution network, cannot meet N-1 safety verification, and is difficult to efficiently and accurately select the grid connection scheme adopted by the distributed power supply in the distribution network. The grid connection scheme of the distributed power supply is selected more efficiently and accurately.

[0182] See also Figure 5 , Figure 5 This is a structural block diagram of a distributed power supply grid connection scheme selection device provided in the third embodiment of the present invention.

[0183] An embodiment of the present invention provides a distributed power supply grid connection scheme selection device, comprising:

[0184] The data acquisition module 501 is configured to respond to an input grid connection request and acquire basic device data and multiple grid connection plans carried in the grid connection request;

[0185] An evaluation index matrix construction module 502 is used to calculate multiple evaluation indicators corresponding to each grid connection scheme based on the basic equipment data, and construct an evaluation index matrix using the multiple evaluation indicators;

[0186] The optimal indicator matrix construction module 503 is used to select the optimal indicator in the evaluation indicator matrix and construct the optimal indicator matrix;

[0187] A correlation matrix generating module 504 is used to calculate correlation coefficients based on the evaluation index matrix and the optimal index matrix, and generate a correlation matrix using the correlation coefficients;

[0188] The target grid connection scheme determination module 505 is used to determine and output the target grid connection scheme based on a preset weight coefficient matrix and a correlation matrix.

[0189] Optionally, the evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; the evaluation indicator matrix construction module 502 includes:

[0190] The data extraction submodule is used to extract the transformer rated capacity, transformer transfer load, transformer load rate and tie line capacity from the equipment basic data;

[0191] A safety and stability evaluation index calculation submodule is used to calculate the safety and stability evaluation index based on the transformer rated capacity, transformer transfer load, transformer load rate and tie line capacity;

[0192] The distribution network evaluation index calculation submodule is used to determine various distribution network evaluation indicators based on basic equipment data;

[0193] The evaluation index matrix construction submodule is used to construct the evaluation index matrix using safety and stability evaluation indicators and multiple distribution network evaluation indicators.

[0194] Optionally, the safety and stability evaluation index calculation submodule is specifically configured to: determine whether each grid connection scheme meets preset constraint conditions based on the transformer rated capacity, transformer transfer load, transformer load rate, and tie line capacity; if so, calculate the safety and stability evaluation index using the transformer rated capacity and transformer load rate in combination with a safety margin calculation formula;

[0195] If not satisfied, the grid connection plan will be deleted;

[0196] The constraints are:

[0197]

[0198] Among them, Ω DSSR is the set of all transformers, R i 、R j are the rated capacity of transformer i and transformer j respectively, B ij is the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, C ij is the capacity of the tie line between transformer i and transformer j, G is the preset lower limit of load, T i 、T j are the transformer load factors of transformer i and transformer j respectively;

[0199] The safety margin calculation formula is:

[0200]

[0201] Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

[0202] Optionally, the association matrix generating module 504 includes:

[0203] The matrix normalization submodule is used to perform normalization preprocessing on the evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix according to a preset normalization formula to obtain a normalized matrix;

[0204] The correlation coefficient calculation submodule is used to calculate the correlation coefficient between each evaluation indicator in the normalized matrix and the corresponding optimal indicator using a preset correlation coefficient calculation formula;

[0205] The correlation ranking submodule is used to group the grid-connected schemes and sort the correlation coefficients to generate a correlation matrix;

[0206] The normalization formula is:

[0207]

[0208] Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the kth evaluation indicator; is the maximum value of the kth evaluation indicator;

[0209] The correlation coefficient calculation formula is:

[0210]

[0211] Among them, i (k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid-connected scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

[0212] Optionally, the target grid-connected scheme determination module 505 includes: a correlation submatrix extraction submodule, used to extract the correlation submatrix corresponding to each grid-connected scheme from the correlation matrix; a comprehensive correlation calculation submodule, used to use a preset weight coefficient matrix and each correlation submatrix to calculate the comprehensive correlation corresponding to each grid-connected scheme; a scheme sorting submodule, used to sort all grid-connected schemes from high to low according to the comprehensive correlation, select the grid-connected scheme with the highest comprehensive correlation as the target grid-connected scheme and output it.

[0213] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices, modules and sub-modules can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0214] In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0215] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0216] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for selecting a grid-connected scheme for distributed power sources, characterized in that: include: In response to an input grid connection request, obtaining basic device data and a plurality of grid connection schemes carried in the grid connection request; Calculating multiple evaluation indicators corresponding to each of the grid-connected schemes based on the equipment basic data, and constructing an evaluation indicator matrix using the multiple evaluation indicators; Selecting the optimal indicator in the evaluation indicator matrix to construct an optimal indicator matrix; Calculating correlation coefficients based on the evaluation index matrix and the optimal index matrix, and generating a correlation matrix using the correlation coefficients; Determine and output a target grid connection plan based on a preset weight coefficient matrix and the correlation matrix; The evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; The step of calculating a plurality of evaluation indicators corresponding to each of the grid-connected schemes according to the equipment basic data, and constructing an evaluation indicator matrix using the plurality of evaluation indicators, comprises: extracting transformer rated capacity, transformer transfer load, transformer load factor and tie line capacity from the equipment basic data; Calculating the safety and stability evaluation index according to the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer and the capacity of the tie line; Determining the plurality of distribution network evaluation indicators based on the equipment basic data; Constructing an evaluation index matrix using the safety and stability evaluation index and the multiple distribution network evaluation indexes; The step of calculating the safety and stability evaluation index according to the rated capacity of the transformer, the transformer transfer load, the transformer load rate and the tie line capacity includes: Determining whether each of the grid-connected schemes meets preset constraints based on the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line; If the conditions are met, the safety and stability evaluation index is calculated using the transformer rated capacity and the transformer load rate in combination with the safety margin calculation formula; If not satisfied, the grid connection plan is deleted; The constraints are: Among them, Ω DSSR is the set of all transformers, R i 、 R j are the transformer rated capacities of transformer i and transformer j respectively, Bi j is the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, Ci j is the capacity of the tie line between transformer i and transformer j, G is the preset lower load limit, T i 、 T j are the transformer load factors of transformer i and transformer j respectively; The safety margin calculation formula is: Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

2. The method according to claim 1, characterized in that The step of calculating correlation coefficients based on the evaluation index matrix and the optimal index matrix, and using the correlation coefficients to generate a correlation matrix includes: Performing normalization preprocessing on the evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix according to a preset normalization formula to obtain a normalized matrix; Calculate the correlation coefficient between each evaluation indicator and the corresponding optimal indicator in the normalized matrix using a preset correlation coefficient calculation formula; According to each of the grid connection schemes as a group, sorting the correlation coefficients to generate a correlation matrix; The normalization formula is: Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the k-th evaluation indicator; is the maximum value of the kth evaluation indicator; The correlation coefficient calculation formula is: Among them, i (k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid connection scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

3. The method according to claim 1, characterized in that The step of determining and outputting a target grid connection scheme based on a preset weight coefficient matrix and the correlation matrix includes: Extracting a correlation submatrix corresponding to each grid connection scheme from the correlation matrix; Using a preset weight coefficient matrix and each of the correlation degree sub-matrices, respectively calculating the comprehensive correlation degree corresponding to each of the grid connection schemes; All the grid-connected schemes are sorted from high to low according to the comprehensive correlation, and the grid-connected scheme with the highest comprehensive correlation is selected as the target grid-connected scheme and output.

4. A distributed power grid connection scheme selection device, characterized in that: include: A data acquisition module, configured to respond to an input grid connection request and acquire basic device data and a plurality of grid connection schemes carried in the grid connection request; An evaluation index matrix construction module is used to calculate a plurality of evaluation indicators corresponding to each of the grid-connected schemes according to the equipment basic data, and to construct an evaluation index matrix using the plurality of evaluation indicators; An optimal indicator matrix construction module is used to select the optimal indicator in the evaluation indicator matrix and construct the optimal indicator matrix; A correlation matrix generation module is used to calculate the correlation coefficient based on the evaluation index matrix and the optimal index matrix, and generate a correlation matrix using the correlation coefficient; A target grid connection scheme determination module is used to determine and output a target grid connection scheme based on a preset weight coefficient matrix and the correlation matrix; The evaluation indicators include safety and stability evaluation indicators and multiple distribution network evaluation indicators; The evaluation indicator matrix construction module includes: A data extraction submodule, configured to extract transformer rated capacity, transformer transfer load, transformer load rate, and tie line capacity from the equipment basic data; A safety and stability evaluation index calculation submodule, configured to calculate the safety and stability evaluation index according to the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line; A distribution network evaluation index calculation submodule, configured to determine the plurality of distribution network evaluation indicators based on the equipment basic data; An evaluation index matrix construction submodule, configured to construct an evaluation index matrix using the safety and stability evaluation index and the multiple distribution network evaluation indicators; The safety and stability evaluation index calculation submodule is specifically used to: Determining whether each of the grid-connected schemes meets preset constraints based on the rated capacity of the transformer, the transferred load of the transformer, the load rate of the transformer, and the capacity of the tie line; If the conditions are met, the safety and stability evaluation index is calculated using the transformer rated capacity and the transformer load rate in combination with the safety margin calculation formula; If not satisfied, the grid connection plan is deleted; The constraints are: Among them, Ω DSSR is the set of all transformers, R i 、 R j are the transformer rated capacities of transformer i and transformer j respectively, Bi j is the transformer transfer load transferred from transformer i to transformer j after a fault occurs on transformer i, k is the preset short-term load overload factor, Ci j is the capacity of the tie line between transformer i and transformer j, G is the preset lower load limit, T i 、 T j are the transformer load factors of transformer i and transformer j respectively; The safety margin calculation formula is: Where n is the number of transformers, U i is the i-th contact unit, transformer i is the contact center, R l is the rated capacity of transformer l, T l is the transformer load factor of transformer 1.

5. The device according to claim 4, characterized in that The association matrix generation module includes: A matrix normalization submodule is used to perform normalization preprocessing on the evaluation indicators in the evaluation indicator matrix and the optimal indicators in the optimal indicator matrix according to a preset normalization formula to obtain a normalized matrix; A correlation coefficient calculation submodule is used to calculate the correlation coefficient between each evaluation indicator and the corresponding optimal indicator in the normalized matrix using a preset correlation coefficient calculation formula; A correlation ranking submodule is used to group the grid-connected schemes and sort the correlation coefficients to generate a correlation matrix; The normalization formula is: Among them, λ ik is the kth evaluation index X in the i-th grid connection scheme ik The value after standard preprocessing; is the minimum value of the k-th evaluation indicator; is the maximum value of the kth evaluation indicator; The correlation coefficient calculation formula is: Among them, i (k) is the correlation coefficient between the kth evaluation index and the kth optimal index in the i-th grid connection scheme, λ 0k is the kth optimal indicator, ρ is the preset parameter, ρ∈0,1.

6. The device according to claim 5, characterized in that The target grid connection scheme determination module includes: A correlation degree sub-matrix extraction sub-module, configured to extract a correlation degree sub-matrix corresponding to each grid connection scheme from the correlation degree matrix; A comprehensive correlation calculation submodule, configured to calculate the comprehensive correlation corresponding to each of the grid-connected schemes using a preset weight coefficient matrix and each of the correlation sub-matrices; The scheme sorting submodule is used to sort all the grid-connected schemes from high to low according to the comprehensive correlation, select the grid-connected scheme with the highest comprehensive correlation as the target grid-connected scheme and output it.

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