Offshore wind power transmission planning method and system considering capacity reduction configuration

Abstract

The application provides a kind of offshore wind power transmission planning method and system considering capacity reduction configuration, belong to power system planning technical field. Including: constructing upper optimization model for determining the topology structure and capacity configuration of offshore wind power transmission system, the upper optimization model constructed is solved by heuristic algorithm, and the preliminary offshore transmission system topology structure and transmission channel capacity configuration scheme are obtained;A lower optimization model for simulating the clearing process of power market is constructed, and the lower optimization model includes day-ahead market clearing model and real-time market clearing model;The preliminary offshore transmission system topology structure and transmission channel capacity configuration obtained are used as boundary conditions, and the lower optimization model constructed is iteratively solved until the result converges, and the final offshore wind power transmission system planning scheme is obtained. The collaborative optimization of transmission system investment and power market income is realized, and the economic efficiency and the robustness of responding to wind power uncertainty of the planning scheme are improved.

Description

Technical Field

[0001] This invention belongs to the field of power system planning technology, specifically relating to a method and system for offshore wind power transmission planning that considers capacity reduction configuration. Background Technology

[0002] In recent years, my country's offshore wind power industry has developed rapidly, and my country's offshore wind power has gradually moved from nearshore to deep-sea and nationally managed sea areas. The planning of transmission schemes for deep-sea wind farms requires a comprehensive balance of costs and benefits. The choice of transmission technology and the design of channel capacity will lead to changes in costs. At the same time, under the influence of the electricity market mechanism, the revenue from wind power sales also has a profound impact on the planning scheme.

[0003] Currently, there are three technical solutions for offshore wind power transmission systems: power frequency transmission, direct current transmission, and frequency division / low frequency transmission. Power frequency transmission enables economical grid connection for small-capacity units, while direct current transmission enables grid connection for large-capacity units but is less economical. Frequency division / low frequency transmission, on the other hand, can transmit more electrical energy with the same number of channels.

[0004] After offshore wind power is connected to the onshore grid, the reconstruction of the onshore power grid must be considered to prevent the power from being unable to be transmitted. Since grid companies no longer fully absorb offshore wind power generation, and the electricity generated by offshore wind power is settled by the market, the revenue from electricity sales is difficult to accurately assess. Therefore, only by achieving coordinated planning of the offshore transmission system and the onshore power grid, while considering the power market operation mechanism, can the economic viability of the offshore wind power transmission system planning scheme be accurately calculated.

[0005] Existing planning technologies have the following drawbacks: Generally, only one technical solution is considered, and the three mainstream power transmission methods of AC power transmission, DC power transmission and frequency division / low frequency power transmission are not comprehensively considered. The discussion on multiple power transmission methods for offshore wind power is not comprehensive. The capacity configuration of transmission channels mainly depends on the rated capacity of offshore wind turbines. However, due to the low average utilization hours of offshore wind power, the mismatch between channel capacity and actual utilization hours leads to a waste of resources. Planning models generally neglect the electricity market environment and do not incorporate electricity market revenue models, which leads to significant differences between planning results and actual returns, potentially causing biases in investment decisions.

[0006] Against this backdrop, there is an urgent need for a comprehensive planning theory and methodology system for deep-sea wind power, which includes multi-technology scheme comparison, grid-source synergy optimization, and market-driven revenue. Summary of the Invention

[0007] The purpose of this invention is to overcome the above-mentioned shortcomings and provide a method and system for selecting sentinel turbine units suitable for unmanned aerial vehicle (UAV) wind farms. It comprehensively considers three mainstream power transmission methods—power frequency transmission, DC transmission, and frequency-division / low-frequency transmission—and, based on the economic capacity configuration of the transmission channel and the market revenue of the wind farm, accurately calculates the economic efficiency of the offshore wind power transmission system planning scheme, and achieves optimal generation of the offshore wind farm transmission system.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an offshore wind power transmission planning method that considers capacity reduction configuration, comprising the following steps: An upper-level optimization model is constructed to determine the topology and capacity configuration of the offshore wind power transmission system. The constructed upper-level optimization model is solved by a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. A lower-level optimization model is constructed to simulate the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. Using the preliminary obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions, the constructed lower-level optimization model is iteratively solved until the results converge, thus obtaining the final offshore wind power transmission system planning scheme.

[0009] In the step of constructing an upper-level optimization model for determining the topology and capacity configuration of an offshore wind power transmission system, and solving the constructed upper-level optimization model using a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme, the constructed upper-level optimization model is as follows:

[0010] in, Equivalent annual profit For cable construction costs; Construction costs for onshore converter stations and substations; Construction costs for offshore converter stations and substations; For the line Construction variables; For the line The renovation cost; This refers to the number of years the equipment has been in operation.

[0011] The converter stations and substations include power frequency AC boost type, DC transmission converter type, and frequency division / low frequency converter type.

[0012] The constraints of the upper-level optimization model include: Converter station type matching constraint: The types of offshore converter stations and onshore substations connected by lines should match; Power balance constraints: Ensure the balance between the power output from offshore wind farms, the power output from offshore converters / substations, and the power output from onshore converters / substations; Power transmission constraints: The power transmission capacity of lines and nodes in offshore power grids shall meet the upper limit of their power capacity and construction constraints.

[0013] In the step of constructing a lower-level optimization model to simulate the clearing process of the electricity market, the lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on wind power forecasts, and the real-time market clearing model adjusts based on the change in actual wind power generation relative to the day-ahead market clearing result. The constructed day-ahead market clearing model is as follows:

[0014] in, This indicates the predicted winning bid power for offshore wind power. This indicates the price quote for wind turbine units; This represents the predicted winning bid power for traditional generating units, in MW. This indicates the price quote for a traditional generator set.

[0015] The constraints of the day-ahead market clearing model include power balance constraints, upper and lower limits of output of traditional units, and line transmission capacity constraints.

[0016] The constructed real-time market clearing model is as follows:

[0017] in, This indicates the actual winning bid power for offshore wind power; This indicates the actual price quoted for the wind turbine unit; This indicates the winning bid power of a traditional generator unit, in MW; This indicates the actual price quoted for a conventional generator set.

[0018] The constraints of the real-time market clearing model are as follows: The increase in offshore wind power generation shall not exceed the total reduction in reserve capacity of traditional units in the system; the decrease in offshore wind power generation shall not exceed the total increase in reserve capacity of traditional units in the system.

[0019] The method for using the initially obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, and obtaining the final offshore wind power transmission system planning scheme, is as follows: Using the initial topology as boundary conditions, the lower-level optimization model is solved using mathematical programming. Based on the obtained node marginal electricity price differences, the onshore transmission lines that need to be rebuilt are identified and determined, and a scheme for the onshore power grid to be rebuilt is generated. Based on the onshore power grid scheme to be rebuilt, and combined with the real-time market clearing model, the operating status and electricity market clearing results of the offshore wind power transmission system are obtained. The operating status is fed back to the heuristic algorithm, and the above steps are repeated until the result converges, outputting the final offshore wind power transmission system planning scheme.

[0020] Secondly, the present invention provides an offshore wind power transmission planning system that considers capacity reduction configuration, comprising: The upper-level optimization model construction module constructs an upper-level optimization model to determine the topology and capacity configuration of the offshore wind power transmission system. The constructed upper-level optimization model is solved through a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. The lower-level optimization model construction module constructs a lower-level optimization model for simulating the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. The calculation module is used to use the initially obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, thus obtaining the final offshore wind power transmission system planning scheme.

[0021] Compared with the prior art, the present invention has the following beneficial effects: This invention provides an offshore wind power transmission planning method that considers capacity reduction configuration. It constructs a two-layer optimization model: the upper-layer model depicts the transmission system topology, equipment selection, and capacity configuration; the lower-layer model fully simulates the clearing process and deviation assessment mechanism of the day-ahead and real-time electricity markets. This overcomes the limitation of traditional planning methods where investment decisions and market operations are separated, enabling the planning scheme to truly reflect the impact of market rules on system operation. By introducing day-ahead forecast power declaration and real-time generation curve adjustment mechanisms into the two-layer model, and assessing output deviations in the real-time market, the method fully considers the impact of the randomness and volatility of wind power output on system operation. This allows the final planning scheme to adapt to the uncertainties of wind power at different time scales, enhancing the system's operational flexibility and reliability.

[0022] Furthermore, a hybrid solution strategy combining heuristic algorithms and mathematical programming methods is proposed. Heuristic algorithms are used to handle the discrete combinatorial optimization problem of the upper-level topology, while mathematical programming methods are used to efficiently solve the lower-level linear market clearing model. Finally, the onshore lines requiring reconstruction are accurately identified through nodal marginal price differences. This strategy ensures global optimization capability while significantly reducing computational complexity, demonstrating good engineering applicability. It not only focuses on the topology design of offshore transmission systems but also identifies congestion risks in the onshore power grid through nodal marginal price differences and automatically generates reconstruction schemes for onshore lines. This achieves integrated collaborative planning of the offshore and onshore transmission networks, effectively avoiding power flow exceeding limits in the onshore power grid caused by large-scale offshore wind power grid connection, and ensuring the safe and stable operation of the system.

[0023] Furthermore, this invention introduces a differential settlement model based on the mechanism-based electricity price in the revenue calculation, which accurately reflects the policy requirements of the current transition from full guaranteed purchase to market-based competition. This makes the planning results more in line with the actual operation scenarios of domestic offshore wind power projects and improves the policy adaptability of the technical solution. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0025] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0026] Example 1 like Figure 1 As shown, an offshore wind power transmission planning method considering capacity reduction configuration includes the following steps: S1: Construct an upper-level optimization model to determine the topology and capacity configuration of the offshore wind power transmission system. Solve the constructed upper-level optimization model using a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. S2: Construct a lower-level optimization model for simulating the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. S3: Using the preliminary obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions, iteratively solve the constructed lower-level optimization model until the results converge, and obtain the final offshore wind power transmission system planning scheme.

[0027] Specifically, in S1, an upper-level optimization model is constructed to determine the topology and capacity configuration of the offshore wind power transmission system. The upper-level optimization model uses transmission line construction variables, converter station / substation construction variables, and type variables as decision variables, and the topological connectivity constraints, power balance constraints, and transmission channel capacity constraints of the offshore power transmission system as constraints. The constructed upper-level optimization model is solved through a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme.

[0028] The power transmission channel capacity configuration allows its configured capacity to be lower than the rated capacity of offshore wind power, and the converter station / substation types include power frequency AC boost type, DC transmission converter type and frequency division / low frequency converter type.

[0029] The upper-level optimization model aims to maximize the annual profit. To balance the long-term construction costs of offshore wind power and the short-term returns of the electricity market, the construction costs of offshore wind power are factored into the operational lifespan. Converted to annualized cost. The investment cost of offshore power transmission networks includes cable construction costs. Construction costs of onshore converter stations and substations Construction costs of offshore converter stations and substations After connecting offshore wind turbines to the onshore power grid through a connection point, the amount of electricity received at the connection point increases. To prevent power flow exceeding limits on the onshore lines, the onshore power grid needs to be modified to increase the transmission capacity of the lines. The objective function is expressed as follows:

[0030] in, For annual profit, a binary variable For the line Construction variables, if This indicates that the line does not need to be rebuilt. This indicates that the line needs to be rebuilt; For the line The renovation cost was 10,000 yuan.

[0031] Furthermore, the cable construction cost includes the lines from offshore wind farms to offshore converter stations and substations, the lines from offshore converter stations and substations to onshore converter stations and substations, and the lines from onshore converter stations and substations to the grid connection point. The formula for cable construction cost is as follows:

[0032] in: , , , , These are candidate sets for offshore wind power, offshore converter / substations, onshore converter / substations, onshore grid connection points, and converter / substation types; binary variables. , , Offshore wind power With offshore converter / substation Cable construction variables, offshore converter / substation With onshore converter / substation Cable construction variables, onshore converter / substation With grid connection point The cable construction variable is set to 1; if it is 1, the cable will be constructed, otherwise it will not be constructed. , , Offshore wind power With offshore converter / substation Cost per unit length of cable lines, offshore converter / substation With onshore converter / substation The cost per unit length of cable lines, onshore converter / substations With grid connection point The cost per unit length of cable lines; , , Offshore wind power With offshore converter / substation Cable line length, offshore converter / substation With onshore converter / substation Cable line length, onshore converter / substation With grid connection point The length of the cable line; For offshore converter / substation Variables of type , if Offshore converter / substation For an offshore power frequency AC step-up substation, if Offshore converter / substation For offshore DC power transmission converter stations, if Offshore converter / substation It is a frequency division / low frequency converter station; For onshore converter / substation Variables of type , if Onshore converter / substation For onshore power frequency step-up substations, if Onshore converter / substation For a land-based DC transmission converter station, if Onshore converter / substation It is a land-based frequency division / low-frequency converter station.

[0033] The construction cost of the line from an offshore converter station to an onshore converter station is affected by the type of converter station. The construction cost of both offshore and onshore converter stations varies depending on their maximum conversion power and type.

[0034]

[0035] in, For offshore converter / substation Construction variables, if Then construct offshore converter / substations. Otherwise, offshore converter / substations will not be built. ; For offshore converter / substation Maximum conversion power; For offshore converter / substation The unit power cost of construction; For onshore converter / substation Construction variables, if Then construct onshore converter / substations. Otherwise, onshore converter / substations will not be built. ; For onshore converter / substation Maximum conversion power; For onshore converter / substation The unit power cost of construction.

[0036] Furthermore, line reconstruction in DC power flow can be described using changes in line reactance:

[0037] in: Indicates the line Reactance ; Indicates the route before reconstruction Reactance ; Indicates the reconstruction of the line The change in reactance .

[0038] Furthermore, the constraints for offshore power transmission in the constructed upper-level optimization model include: 1) The planned types of offshore converters and substations, and onshore converters and substations, are determined by a binary variable. and To control that a variable has at most one type, construct a binary variable. and It indicates whether or not it has been built.

[0039]

[0040]

[0041] The types of offshore converter stations and onshore substations connected by lines should be matched, and the following constraints should be established:

[0042] 2) To ensure that the offshore power grid can transmit the electricity generated by the offshore wind turbines, the offshore power transmission system should maintain a balance of electrical energy, with the following specific constraints: Balance of electricity delivered by offshore wind farms:

[0043] Power balance of offshore converter / substation:

[0044] Power balance of onshore converter / substation:

[0045] in Defined as channel capacity, considering its flexible configuration, its configured capacity is allowed to be lower than the rated capacity of offshore wind power; Offshore wind power The installed capacity, MW; Indicates offshore wind power To offshore converter / substation Power, MW; Indicates offshore converter / substation To onshore converter / substation Power, MW; Indicates onshore converter / substation to grid connection point The power, MW.

[0046] 3) The power transmission capacity of lines and nodes in offshore power grids shall meet the upper limit of their power capacity and construction constraints.

[0047] (2-12) (2-13) (2-14) (2-15) (2-16) in: Indicates offshore converter / substation The upper limit of power, MW; Indicates onshore converter / substation The upper limit of power, MW; , , These represent the maximum power rating of the corresponding cable, in MW.

[0048] Specifically, in S2, a lower-level optimization model is constructed to simulate the clearing process of the electricity market. This lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on predicted wind power, while the real-time market clearing model adjusts based on the change in actual wind power generation relative to the day-ahead market clearing result. Predicted wind power and traditional turbine power can be obtained using typical physical methods, statistical and machine learning methods, and deep learning, which are existing technologies and will not be elaborated upon here.

[0049] I. The electricity market operator purchases electricity with the goal of minimizing the overall electricity purchase cost for the society. The day-ahead market clearing model is as follows:

[0050] in: This indicates the predicted winning bid power for offshore wind power, in MW. This indicates the price of wind turbine units, expressed in yuan / MWh; This represents the predicted winning bid power for traditional generating units, in MW. This indicates the price of a traditional thermal power unit, expressed in yuan / MWh.

[0051] The constraints of the constructed day-ahead market clearing model are as follows: 1) The active power balance at nodes under DC power flow reconstruction can be described by the following formula: , , Represents the active power of conventional turbines, offshore wind power, and loads connected to this node, and denotes the dual variable of this constraint as... :

[0052]

[0053] in: Indicates that constraints will be applied. The dual variable is denoted as marginal electricity price at power system nodes Determined by the dual variables in the previous declaration; This represents the phase angle of the first node; This represents the phase angle of the second node.

[0054] 2) To simplify the solution, only the upper and lower limits of the output of traditional units (thermal power units) are considered.

[0055]

[0056] In the formula: and These represent the upper and lower power limits of a traditional generator unit, in MW.

[0057] 3) The active power of the constrained line Internally, to ensure that the system power flow does not exceed the limit, It is determined by the parameters of the line.

[0058]

[0059] The winning bid power for offshore wind power is limited by the predicted output and the transmission capacity of the transmission lines.

[0060]

[0061]

[0062] in: This indicates the upper limit of the predicted power output of offshore wind power, expressed in MW. This indicates the upper limit of power output for offshore wind power channels, expressed in MW.

[0063] II. The electricity market operator, aiming to minimize the system's electricity purchase cost and considering deviation assessments for offshore wind power, constructs the following real-time market clearing model:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] in, This indicates the actual winning bid power for offshore wind power; This indicates the actual price quoted for the wind turbine unit; This indicates the winning bid power of a traditional generator unit, in MW; This indicates the actual price quoted for a conventional generator set.

[0071] In the real-time market, the additional generation capacity of offshore wind power is defined based on the day-ahead market winning bid power. and power reduction To meet the constraints of the system's real-time adjustment capability, the upward adjustment of offshore wind power should not exceed the total downward adjustment of reserve capacity of traditional adjustable turbines in the system, and the downward adjustment of offshore wind power should not exceed the total upward adjustment of reserve capacity of traditional adjustable turbines.

[0072]

[0073]

[0074]

[0075] Specifically, in S3, the initially obtained offshore power transmission system topology and transmission channel capacity configuration are used as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, yielding the final offshore wind power transmission system planning scheme. The specific method is as follows: S31: Use a heuristic algorithm to solve the upper-level optimization model to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme; set the population size, crossover and mutation probability and maximum number of iterations of the heuristic algorithm, and randomly generate an initial set of offshore power transmission system topology schemes as the result of the upper-level optimization model; S32: Using the initial topology as boundary conditions, solve the lower-level optimization model using mathematical programming methods, and based on the obtained node marginal electricity price differences, identify and determine the onshore transmission lines that need to be rebuilt, and generate the onshore power grid scheme to be rebuilt. For each topology scheme, the day-ahead market clearing model is solved using mathematical programming methods (such as the simplex method or interior point method) to obtain the day-ahead marginal electricity price of each node in each time period. Based on the day-ahead marginal electricity price, the price difference between adjacent nodes is calculated. If the price difference between the two nodes of a certain landline exceeds a preset threshold, it is determined that the line has a congestion risk and needs to be expanded and rebuilt. Based on this, the landline reconstruction scheme is determined.

[0076] S33: Based on the onshore power grid scheme to be rebuilt, and combined with the real-time market clearing model, the operating status and electricity market clearing results of the offshore wind power transmission system are obtained; The mathematical programming method is used to solve the model to obtain the increased and decreased power generation of offshore wind power in each typical day and time period, as well as the corresponding real-time marginal electricity price, and then calculate the electricity sales revenue of offshore wind power in the electricity market.

[0077] After real-time market clearing, the revenue from selling offshore wind power can be calculated as follows:

[0078] in: The power output of offshore wind power is expressed in MW. This indicates the reduced power output of offshore wind power, expressed in MW. Indicates a typical day Down The nodal price of offshore wind power grid connection points, in yuan / MWh.

[0079] Currently, China uses a mechanism-based electricity pricing model as a transition from a full purchase model to a market-competitive model. By purchasing a portion of the electricity generated from offshore wind power through this model, the price difference is settled, thereby stabilizing the revenue of new energy projects. Since the calculation ratios and prices for mechanism-based electricity pricing vary across provinces, this paper uses the following method for estimation:

[0080]

[0081] in, The capacity of an offshore wind turbine is expressed in MWh. This indicates the percentage of electricity consumed by the mechanism, taken as 30%. The benchmark for the project's annual power generation utilization hours is 3500 hours. The mechanism price for offshore wind power is set at 396 yuan / MWh.

[0082] S34: Feed back the operating status to the heuristic algorithm, repeat steps S31 to S34 until the result converges, and output the final offshore wind power transmission system planning scheme.

[0083] The electricity sales revenue is combined with the annualized construction cost calculated by the upper-level optimization model to calculate the equivalent annual profit of each topology scheme. Based on the obtained equivalent annual profit, a new generation of topology schemes is generated by using heuristic algorithms for selection, crossover, and mutation operations. Steps S31 to S34 are repeated until the preset maximum number of iterations is reached or the change in the optimal fitness value over multiple consecutive generations is less than the preset convergence threshold. The current optimal offshore power transmission system topology, equipment selection, and capacity configuration scheme are then output as the final offshore wind power transmission system planning scheme.

[0084] Example 2 An offshore wind power transmission planning system that considers capacity reduction configuration includes: The upper-level optimization model construction module constructs an upper-level optimization model to determine the topology and capacity configuration of the offshore wind power transmission system. The constructed upper-level optimization model is solved through a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. The lower-level optimization model construction module constructs a lower-level optimization model for simulating the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. The calculation module is used to use the initially obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, thus obtaining the final offshore wind power transmission system planning scheme.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for offshore wind power transmission planning that considers capacity reduction configuration, characterized in that, Includes the following steps: An upper-level optimization model is constructed to determine the topology and capacity configuration of the offshore wind power transmission system. The constructed upper-level optimization model is solved by a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. A lower-level optimization model is constructed to simulate the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. Using the preliminary obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions, the constructed lower-level optimization model is iteratively solved until the results converge, thus obtaining the final offshore wind power transmission system planning scheme.

2. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 1, characterized in that, In the step of constructing an upper-level optimization model for determining the topology and capacity configuration of an offshore wind power transmission system, and solving the constructed upper-level optimization model using a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme, the constructed upper-level optimization model is as follows: in, Equivalent annual profit For cable construction costs; Construction costs for onshore converter stations and substations; Construction costs for offshore converter stations and substations; For the line Construction variables; For the line The renovation cost; This refers to the number of years the equipment has been in operation.

3. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 2, characterized in that, The converter stations and substations include power frequency AC boost type, DC transmission converter type, and frequency division / low frequency converter type.

4. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 2, characterized in that, The constraints of the upper-level optimization model include: Converter station type matching constraint: The types of offshore converter stations and onshore substations connected by lines should match; Power balance constraints: Ensure the balance between the power output from offshore wind farms, the power output from offshore converters / substations, and the power output from onshore converters / substations; Power transmission constraints: The power transmission capacity of lines and nodes in offshore power grids shall meet the upper limit of their power capacity and construction constraints.

5. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 1, characterized in that, In the step of constructing a lower-level optimization model to simulate the clearing process of the electricity market, the lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on wind power forecasts, and the real-time market clearing model adjusts based on the change in actual wind power generation relative to the day-ahead market clearing result. The constructed day-ahead market clearing model is as follows: in, This indicates the predicted winning bid power for offshore wind power. This indicates the price quote for wind turbine units; This represents the predicted winning bid power for traditional generating units, in MW. This indicates the price quote for a traditional generator set.

6. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 5, characterized in that, The constraints of the day-ahead market clearing model include power balance constraints, upper and lower limits of output of traditional units, and line transmission capacity constraints.

7. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 5, characterized in that, The constructed real-time market clearing model is as follows: in, This indicates the actual winning bid power for offshore wind power; This indicates the actual price quoted for the wind turbine unit; This indicates the winning bid power of a traditional generator unit, in MW; This indicates the actual price quoted for a conventional generator set.

8. The offshore wind power transmission planning method considering capacity reduction configuration according to claim 7, characterized in that, The constraints of the real-time market clearing model are as follows: The increase in offshore wind power generation shall not exceed the total reduction in reserve capacity of traditional units in the system; the decrease in offshore wind power generation shall not exceed the total increase in reserve capacity of traditional units in the system.

9. A method for offshore wind power transmission planning considering capacity reduction configuration according to claim 7, characterized in that, The method for using the initially obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, and obtaining the final offshore wind power transmission system planning scheme, is as follows: Using the initial topology as boundary conditions, the lower-level optimization model is solved using mathematical programming. Based on the obtained node marginal electricity price differences, the onshore transmission lines that need to be rebuilt are identified and determined, and a scheme for the onshore power grid to be rebuilt is generated. Based on the onshore power grid scheme to be rebuilt, and combined with the real-time market clearing model, the operating status and electricity market clearing results of the offshore wind power transmission system are obtained. The operating status is fed back to the heuristic algorithm, and the above steps are repeated until the result converges, outputting the final offshore wind power transmission system planning scheme.

10. An offshore wind power transmission planning system considering capacity reduction configuration, based on the offshore wind power transmission planning method for capacity reduction configuration according to any one of claims 1 to 9, characterized in that, include: The upper-level optimization model construction module constructs an upper-level optimization model to determine the topology and capacity configuration of the offshore wind power transmission system. The constructed upper-level optimization model is solved through a heuristic algorithm to obtain a preliminary offshore power transmission system topology and transmission channel capacity configuration scheme. The lower-level optimization model construction module constructs a lower-level optimization model for simulating the clearing process of the electricity market. The lower-level optimization model includes a day-ahead market clearing model and a real-time market clearing model. The day-ahead market clearing model clears based on the predicted wind power, and the real-time market clearing model is adjusted based on the change in the actual wind power generation relative to the day-ahead market clearing result. The calculation module is used to use the initially obtained offshore power transmission system topology and transmission channel capacity configuration as boundary conditions to iteratively solve the constructed lower-level optimization model until the results converge, thus obtaining the final offshore wind power transmission system planning scheme.

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