Line engineering optimization method and system considering load rate and power supply capacity

Abstract

The application discloses a line engineering optimization method considering load rate and power supply capacity, comprising the following steps: obtaining data information of a target power system; constructing a line engineering optimization target function based on load rate balance and maximum power supply capacity improvement of the target power system; constructing line engineering optimization constraint conditions according to planning upper limit and operation process requirements of the target power system; constructing power flow relaxation variable constraints and power flow checking constraints under a line N-1 fault scene; and optimizing and solving the constructed model to obtain a final line engineering optimization result considering load rate and power supply capacity. The application also discloses a system for implementing the line engineering optimization method considering load rate and power supply capacity. The application not only realizes line engineering optimization of the target power system considering load rate and power supply capacity, but also has higher reliability and better accuracy.

Description

Technical Field

[0001] This invention belongs to the field of electrical automation, and specifically relates to a method and system for optimizing line engineering considering load rate and power supply capacity. Background Technology

[0002] With economic and technological development and the improvement of people's living standards, electricity has become an indispensable secondary energy source in people's production and daily life, bringing endless convenience. Therefore, ensuring a stable and reliable supply of electricity has become one of the most important tasks of the power system.

[0003] Currently, the engineering planning of 220 kV lines mainly relies on verification and validation: first, a set of planned line projects is proposed; then, through extensive power flow calculations under specific operating modes, the planning indicators for each line project are gradually calculated; finally, a subjective comparison method is used to comprehensively consider different engineering indicators to determine the optimal line project in the set. However, with the continuous development of urban distribution networks and the increasing load transfer capacity of 110 kV and below power grids, specific operating modes can no longer represent the load distribution of 220 kV substations in the planning target year. This has led to a dramatic increase in the scale of the proposed 220 kV line project set, resulting in a decrease in the adaptability of the existing line engineering planning methods. Furthermore, current line engineering planning indicators only include the proportion of increased transmission capacity and the improvement of the N-1 throughput rate of the regional power grid, lacking a holistic and comprehensive consideration of the power system, resulting in poor reliability and accuracy of existing schemes. Summary of the Invention

[0004] One of the objectives of this invention is to provide a highly reliable and accurate method for optimizing line engineering that takes into account load rate and power supply capacity.

[0005] The second objective of this invention is to provide a system for implementing the preferred method for line engineering that considers load rate and power supply capacity.

[0006] The preferred method for line engineering considering load rate and power supply capacity provided by this invention includes the following steps:

[0007] S1. Obtain data information about the target power system;

[0008] S2. Based on the load balancing and maximum power supply capacity improvement of the target power system, construct the optimal objective function for line engineering;

[0009] S3. Based on the planning upper limit and operational requirements of the target power system, construct optimal constraints for the line engineering;

[0010] S4. Based on the N-1 fault scenario of the line, construct the power flow relaxation variable constraints and power flow verification constraints under the N-1 scenario of the line;

[0011] S5. Optimize and solve the model constructed in steps S2 to S4 to obtain the final optimal result of the line project considering load rate and power supply capacity.

[0012] Step S1, which involves acquiring data information about the target power system, specifically includes the following steps:

[0013] Acquire data information from the target power system;

[0014] The data information includes the number of substations, the maximum power supply capacity of substations, the rated capacity of substations, the upper limit of line engineering planning, the transmission capacity of lines, and the phase angle range of substation busbar nodes.

[0015] Step S2, which involves constructing an objective function for optimizing line engineering based on load balancing and maximum power supply capacity enhancement of the target power system, specifically includes the following steps:

[0016] The following formula is used as the objective function for the optimal selection of the railway line project:

[0017] In the formula To optimize the objective function value for the railway line project; Weighting of the substation load rate balancing index; For substation load rate balancing indicators; The total number of 500 kV and 220 kV substations in the target power system; The maximum power supply capacity of the nth substation in the target power system; Let n be the rated capacity of the nth substation; Weighting of the maximum power supply capacity index; This refers to the maximum power supply capacity indicator.

[0018] Step S3, which involves constructing optimal constraints for the power line project based on the planning ceiling and operational requirements of the target power system, specifically includes the following steps:

[0019] The following formula is used as the upper limit constraint for the line engineering planning:

[0020] In the formula This is a set of project numbers for the proposed railway line. This is the upper limit for the number of planned routes. Let l be the planning state variable for the l-th line project. If the l-th line project is in the planning state, then... If the l-th line project is not in the planning stage, then ;

[0021] The following formula is used as the constraint on the maximum power supply capacity of the substation:

[0022] In the formula The predicted load of the nth substation under normal operating conditions in the target year;

[0023] The following formula is used as the constraint on the maximum power supply capacity of the target power system:

[0024] In the formula The maximum load demand forecast for the target power system within the planning target year;

[0025] The following formula is used as the line power flow constraint for the target power system:

[0026] In the formula Let be the phase angle of the bus node of the i-th substation; Let be the phase angle of the bus node of the j-th substation; The reactance of the l-th line; This represents the active power flow of the l-th line; A set positive integer greater than the set threshold; Let l be the planning state variable for the l-th line project, when And when it is in the planning stage ,when And not in a planning state ,when and hour ; This represents the transmission capacity of the l-th line; This is a set of numbers for existing and planned railway lines.

[0027] The following formula is used as the phase angle constraint for the bus nodes of the substation:

[0028] In the formula Let be the minimum phase angle of the bus node of the i-th substation; This represents the maximum phase angle of the bus node at the i-th substation.

[0029] The following formula is used as the power balance constraint for the substation:

[0030] In the formula This is a collection of 500 kV substations; This is the set of 220 kV lines connected to the nth substation; This represents the downstream power of the 500 kV upstream power grid connected to the nth substation.

[0031] Step S4 involves constructing power flow relaxation variable constraints for the N-1 scenario, specifically including the following steps:

[0032] Construct a set of scenarios for line N-1 faults. , represented as ,in Let l be the fault variable for the l-th line. If no fault occurs on the l-th line, then... If the lth line fails, then , This is a set of numbers for existing lines and lines in the planning stage;

[0033] The following formula is used as the sum of the line power flow relaxation variables in the N-1 scenario. Minimum objective function:

[0034] In the formula Let l be the power flow relaxation variable for the l-th line. In scenario N-1, when power flow exceeds the limit... No power flow exceeded the time limit in scenario N-1 .

[0035] Step S4, which involves constructing power flow verification constraints, specifically includes the following steps:

[0036] The following formula is used as the line power flow verification constraint in the N-1 scenario:

[0037] In the formula Let be the phase angle of the bus node of the i-th substation in the N-1 scenario; Let be the phase angle of the bus node of the j-th substation in scenario N-1; This represents the active power flow of the l-th line in the N-1 scenario.

[0038] Step S5 involves optimizing and solving the model constructed in steps S2 to S4, specifically including the following steps:

[0039] The models constructed in steps S2 to S4 are optimized and solved based on the Karush-Kuhn-Tucker method and the column and constraint generation algorithm.

[0040] This invention also provides a system for implementing the aforementioned method for optimizing line engineering considering load rate and power supply capacity, comprising a data acquisition module, a target construction module, a first constraint module, a second constraint module, and an engineering optimization module; the data acquisition module, target construction module, first constraint module, second constraint module, and engineering optimization module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the target construction module; the target construction module is used to construct an objective function for optimizing line engineering based on the received data information, the load rate balancing and maximum power supply capacity improvement of the target power system, and upload the data information to the first constraint module; the first constraint module is used to construct constraints for optimizing line engineering based on the received data information, the planning upper limit and operation process requirements of the target power system, and upload the data information to the second constraint module; the second constraint module is used to construct power flow relaxation variable constraints and power flow verification constraints under the N-1 fault scenario of the line based on the received data information, and upload the data information to the engineering optimization module; the engineering optimization module is used to optimize and solve the constructed model based on the received data information to obtain the final optimization result of the line engineering considering load rate and power supply capacity.

[0041] The method and system for optimizing power line engineering considering load rate and power supply capacity provided by this invention comprehensively considers the load rate balancing and maximum power supply capacity enhancement of the target power system, and combines the N-1 fault scenario and operational constraints of the target power system. This not only achieves the optimization of power line engineering considering load rate and power supply capacity of the target power system, but also has higher reliability and better accuracy. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0043] Figure 2 This is a schematic diagram illustrating the interconnection between a typical receiving-end provincial power grid and an adjacent provincial power grid in the central region, as described in an embodiment of the method of the present invention.

[0044] Figure 3 This is a schematic diagram showing the load rate and power supply capacity of each substation in an embodiment of the method of the present invention.

[0045] Figure 4 This is a schematic diagram comparing the substation load rates of one proposed power line project and two proposed power line projects, which are embodiments of the present invention.

[0046] Figure 5 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0047] like Figure 1The diagram shown is a flowchart of the method of the present invention: This preferred method for line engineering considering load rate and power supply capacity disclosed in the present invention includes the following steps:

[0048] S1. Obtain data information of the target power system; specifically including the following steps:

[0049] Acquire data information from the target power system;

[0050] The data information includes the number of substations, the maximum power supply capacity of substations, the rated capacity of substations, the upper limit of line engineering planning, and the phase angle range of substation busbar nodes, etc.

[0051] S2. Based on the load balancing and maximum power supply capacity improvement of the target power system, construct the optimal objective function for line engineering; specifically including the following steps:

[0052] The following formula is used as the objective function for the optimal selection of the railway line project:

[0053] In the formula To optimize the objective function value for the railway line project; Weighting of the substation load rate balancing index; For substation load rate balancing indicators; The total number of 500 kV and 220 kV substations in the target power system; The maximum power supply capacity of the nth substation in the target power system; Let n be the rated capacity of the nth substation; Weighting of the maximum power supply capacity index; This refers to the maximum power supply capacity indicator.

[0054] S3. Based on the planning ceiling and operational requirements of the target power system, construct optimal constraints for the power line engineering; specifically including the following steps:

[0055] The following formula is used as the upper limit constraint for the line engineering planning:

[0056] In the formula This refers to the collection of planned railway line projects. This is the upper limit for the number of planned routes. Let l be the planning state variable for the l-th line project. If the l-th line project is in the planning state, then... If the l-th line project is not in the planning stage, then ;

[0057] The following formula is used as the constraint on the maximum power supply capacity of the substation:

[0058] In the formula The predicted load of the nth substation under normal operating conditions in the target year;

[0059] The following formula is used as the constraint on the maximum power supply capacity of the target power system:

[0060] In the formula The maximum load demand forecast for the target power system within the planning target year;

[0061] The following formula is used as the line power flow constraint for the target power system:

[0062] In the formula Let be the phase angle of the bus node of the i-th substation; Let be the phase angle of the bus node of the j-th substation; The reactance of the l-th line; This represents the active power flow of the l-th line; A set positive integer greater than the set threshold; Let l be the planning state variable for the l-th line project, when And when it is in the planning stage ,when And not in a planning state ,when and hour ; This represents the transmission capacity of the l-th line; This is a set of numbers for existing and planned railway lines.

[0063] The following formula is used as the phase angle constraint for the bus nodes of the substation:

[0064] In the formula Let be the minimum phase angle of the bus node of the i-th substation; This represents the maximum phase angle of the bus node at the i-th substation.

[0065] The following formula is used as the power balance constraint for the substation:

[0066] In the formula This is a collection of 500 kV substations; This is the set of 220 kV lines connected to the nth substation; This represents the downstream power of the 500 kV upstream power grid connected to the nth substation.

[0067] S4. Based on the N-1 fault scenario of the line, construct the power flow relaxation variable constraints and power flow verification constraints under the N-1 scenario; specifically including the following steps:

[0068] Construct a set of scenarios for line N-1 faults. , represented as ,in Let l be the fault variable for the l-th line. If no fault occurs on the l-th line, then... If the lth line fails, then , This is a set of numbers for existing lines and lines in the planning stage;

[0069] The following formula is used as the sum of the line power flow relaxation variables in the N-1 scenario. Minimum objective function:

[0070] In the formula Let l be the power flow relaxation variable for the l-th line. In scenario N-1, when power flow exceeds the limit... No power flow exceeded the time limit in scenario N-1 ;

[0071] The following formula is used as the line power flow verification constraint in the N-1 scenario:

[0072] In the formula Let be the phase angle of the bus node of the i-th substation in the N-1 scenario; Let be the phase angle of the bus node of the j-th substation in scenario N-1; For the active power flow of the l-th line in scenario N-1;

[0073] S5. Optimize and solve the models constructed in steps S2-S4 to obtain the final optimal results for the line engineering considering load rate and power supply capacity; specifically including the following steps:

[0074] The models constructed in steps S2 to S4 are optimized and solved based on the Karush-Kuhn-Tucker method and column and constraint generation algorithm. In practice, common mathematical model solvers such as Cplex and Gurobi can be used to solve the model directly.

[0075] The present invention is based on the calculation and analysis of the N-1 throughput, maximum power supply capacity and substation load rate of the regional power grid before and after the commissioning of the planned line project, and selects the optimal planned line project.

[0076] The present invention can quantify the synergy between the power transmission capacity of the regional power grid and the power supply capacity of substations, enrich the connotation of the necessity index of planned lines, and provide a quantitative reference for the optimal decision-making of line engineering.

[0077] The method of the present invention will be further described below with reference to an embodiment:

[0078] The proposed method is analyzed and verified using the actual power grid of a southeastern power supply area in a city in central China as an example. This power supply area is mainly powered by seven 220 kV substations and two 500 kV substations. The locations of the substations, the grid structure, and the proposed line sets are as follows: Figure 2 As shown. Settings , The projected capacity and load of each substation in the planning year are shown in Table 1. Substations 1 and 7 are 500 kV substations and therefore have no direct load supply. The maximum load demand forecast for this power supply area in 2028 is... All newly built lines are calculated based on a transmission capacity of 663MW, while the capacity of other lines is set according to the actual power grid conditions.

[0079] Considering the planned commissioning of one power line project in 2028, the proposed optimal project is the addition of a 220kV line between substations #8 and #9, bringing the maximum regional power supply capacity to 3540MW. This ensures that all 220kV substations within the region operate at near full capacity. Table 2 summarizes the selected power line projects and the corresponding most severe N-1 line scenario during the model optimization calculation. The load factor and power supply capacity of each substation under the maximum regional power supply capacity are also presented. Figure 3 As shown.

[0080] Table 2 shows that the model's recommended routes focus on strengthening the interconnection of 220 kV end substations, especially substations #8 and #9, which are end substations with large service volumes. Given the need to meet both maximum power supply capacity and pass the N-1 check, strengthening interconnection is indeed the priority. Clearly, the optimization method's results align with the actual needs of the power grid. Figure 2 It can be seen that with the construction of a new 220 kV line at substations #8 and #9, the maximum power supply capacity of each substation, including the 500 kV substation, is positively correlated with its capacity, and the substation load rate is relatively balanced. The comprehensive evaluation index of the regional power grid in the target year is calculated. .

[0081] Since the planned single power line in 2028 can maximize the power supply capacity of the region, the rated capacity of the substations in 2030 is further considered. The limiting characteristics of the regional power grid structure on the long-term power supply capacity of the substations in 2026 are studied. Compared to 2026, substations #2, #4, and #6 have each had 2, 1, and 1 240MVA transformers added, respectively. Considering the planned commissioning of one power line project in 2030, the optimal project is calculated to be the addition of one 220kV line between substations #6 and #9. The maximum power supply capacity of the area is 4419MW. Considering the two line projects planned to be put into operation in 2030, the optimal projects are calculated to be adding one 220kV line each to substations #6 and #9, and substations #8 and #9. The maximum power supply capacity of the region is 4500MW. Obviously... The grid load balance and maximum power supply capacity under the commissioning of two transmission line projects are better than those under the commissioning of one transmission line project. Further comparison of substation load rates is needed, such as... Figure 4 As shown. Obviously, the grid structure of only one transmission line project is insufficient to release the maximum power supply capacity of the power grid. The proposed method can balance the load factor of the regional power grid and improve the power supply capacity.

[0082] Different power grids in different service areas have different main grid structures, substation scales, and load distributions, leading to variations in the necessity of corresponding line planning, making subjective comparisons and selections difficult. A comprehensive evaluation index is defined to address this. The proposed method for optimizing power line projects can quantify the synergy between the regional power grid's transmission capacity and the substation's power supply capacity, further incorporating more necessary factors into planning decisions, thereby comprehensively and accurately determining the optimal planned power line projects. Simultaneously, the optimization method of this invention replaces manual traversal verification, solving the problem of the rapidly increasing scale of the planned power line project set under long-term planning conditions, and has significant engineering practical value in actual power grid planning work.

[0083] like Figure 5The diagram shows the functional modules of the system of the present invention: The system disclosed in this invention, which implements the method for optimizing line engineering considering load rate and power supply capacity, includes a data acquisition module, a target construction module, a first constraint module, a second constraint module, and an engineering optimization module; these modules are connected in series. The data acquisition module acquires data information of the target power system and uploads it to the target construction module. The target construction module constructs an objective function for optimizing line engineering based on the received data information, considering load rate balancing and maximum power supply capacity improvement of the target power system, and uploads the data information to the first constraint module. The first constraint module constructs constraints for optimizing line engineering based on the received data information, considering the planning upper limit and operational requirements of the target power system, and uploads the data information to the second constraint module. The second constraint module constructs power flow relaxation variable constraints and power flow verification constraints under the N-1 fault scenario of the line based on the received data information, and uploads the data information to the engineering optimization module. The engineering optimization module optimizes the constructed model based on the received data information to obtain the final optimized result of the line engineering considering load rate and power supply capacity.

Claims

1. A method for optimizing line engineering considering load rate and power supply capacity, comprising the following steps: S1. Obtain data information about the target power system; S2. Based on the load balancing and maximum power supply capacity improvement of the target power system, construct the optimal objective function for line engineering; S3. Based on the planning upper limit and operational requirements of the target power system, construct optimal constraints for the line engineering; S4. Based on the N-1 fault scenario of the line, construct the power flow relaxation variable constraints and power flow verification constraints under the N-1 scenario of the line; S5. Optimize and solve the model constructed in steps S2 to S4 to obtain the final optimal result of the line project considering load rate and power supply capacity.

2. The preferred method for line engineering considering load rate and power supply capacity according to claim 1, characterized in that... Step S1, which involves acquiring data information about the target power system, specifically includes the following steps: Acquire data information from the target power system; The data information includes the number of substations, the maximum power supply capacity of substations, the rated capacity of substations, the upper limit of line engineering planning, and the phase angle range of substation busbar nodes.

3. The preferred method for line engineering considering load rate and power supply capacity according to claim 2, characterized in that... Step S2, which involves constructing an objective function for optimizing line engineering based on load balancing and maximum power supply capacity enhancement of the target power system, specifically includes the following steps: The following formula is used as the objective function for the optimal selection of the railway line project: In the formula To optimize the objective function value for the railway line project; Weighting of the substation load rate balancing index; For substation load rate balancing indicators; The total number of 500 kV and 220 kV substations in the target power system; The maximum power supply capacity of the nth substation in the target power system; Let n be the rated capacity of the nth substation; Weighting of the maximum power supply capacity index; This refers to the maximum power supply capacity indicator.

4. The preferred method for line engineering considering load rate and power supply capacity according to claim 3, characterized in that... Step S3, which involves constructing optimal constraints for the power line project based on the planning ceiling and operational requirements of the target power system, specifically includes the following steps: The following formula is used as the upper limit constraint for the line engineering planning: In the formula This refers to the collection of planned railway line projects. This is the upper limit for the number of planned routes. Let l be the planning state variable for the l-th line project. If the l-th line project is in the planning state, then... If the l-th line project is not in the planning stage, then ; The following formula is used as the constraint on the maximum power supply capacity of the substation: In the formula The predicted load of the nth substation under normal operating conditions in the target year; The following formula is used as the constraint on the maximum power supply capacity of the target power system: In the formula The maximum load demand forecast for the target power system within the planning target year; The following formula is used as the line power flow constraint for the target power system: In the formula Let be the phase angle of the bus node of the i-th substation; Let be the phase angle of the bus node of the j-th substation; The reactance of the l-th line; This represents the active power flow of the l-th line; A set positive integer greater than the set threshold; Let l be the planning state variable for the l-th line project, when And when it is in the planning stage ,when And not in a planning state ,when and hour ; This represents the transmission capacity of the l-th line; This is a set of numbers for existing and planned railway lines. The following formula is used as the phase angle constraint for the bus nodes of the substation: In the formula Let be the minimum phase angle of the bus node of the i-th substation; This represents the maximum phase angle of the bus node at the i-th substation. The following formula is used as the power balance constraint for the substation: In the formula This is a collection of 500 kV substations; This is the set of 220 kV lines connected to the nth substation; This represents the downstream power of the 500 kV upstream power grid connected to the nth substation.

5. The preferred method for line engineering considering load rate and power supply capacity according to claim 4, characterized in that... Step S4 involves constructing power flow relaxation variable constraints for the N-1 scenario, specifically including the following steps: Construct a set of scenarios for line N-1 faults. , represented as ,in Let l be the fault variable for the l-th line. If no fault occurs on the l-th line, then... If the lth line fails, then , This is a set of numbers for existing lines and lines in the planning stage; The following formula is used as the sum of the line power flow relaxation variables in the N-1 scenario. Minimum objective function: In the formula Let l be the power flow relaxation variable for the l-th line. In scenario N-1, when power flow exceeds the limit... No power flow exceeded the time limit in scenario N-1 .

6. The preferred method for line engineering considering load rate and power supply capacity according to claim 5, characterized in that... Step S4, which involves constructing power flow verification constraints, specifically includes the following steps: The following formula is used as the line power flow verification constraint in the N-1 scenario: In the formula Let be the phase angle of the bus node of the i-th substation in the N-1 scenario; Let be the phase angle of the bus node of the j-th substation in scenario N-1; This represents the active power flow of the l-th line in the N-1 scenario.

7. The preferred method for line engineering considering load rate and power supply capacity according to claim 6, characterized in that... Step S5 involves optimizing and solving the model constructed in steps S2 to S4, specifically including the following steps: The models constructed in steps S2 to S4 are optimized and solved based on the Karush-Kuhn-Tucker method and the column and constraint generation algorithm.

8. A system for implementing the preferred method for line engineering considering load rate and power supply capacity as described in any one of claims 1 to 7, characterized in that... It includes a data acquisition module, a target construction module, a first constraint module, a second constraint module, and an engineering optimization module; the data acquisition module, the target construction module, the first constraint module, the second constraint module, and the engineering optimization module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the target construction module; the target construction module is used to construct the line engineering optimization objective function based on the received data information, based on the load rate balancing and maximum power supply capacity improvement of the target power system, and upload the data information to the first constraint module; The first constraint module is used to construct optimal constraint conditions for line engineering based on the received data information, the planning upper limit and operation process requirements of the target power system, and upload the data information to the second constraint module. The second constraint module is used to construct power flow relaxation variable constraints and power flow verification constraints under the N-1 fault scenario of the line based on the received data information, and upload the data information to the engineering optimization module; the engineering optimization module is used to optimize and solve the constructed model based on the received data information to obtain the final optimization result of the line project considering load rate and power supply capacity.

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