Offshore wind power flexible dc grid connection topology optimization design method and system for multi-drop scenario

Abstract

This invention relates to the field of offshore wind power transmission planning technology, and discloses a method and system for optimizing the design of flexible DC grid-connected topologies for offshore wind power in multi-location scenarios. The method includes: acquiring basic parameters of the wind farm, the locations of multiple grid-connected points, and operational constraints; constructing an initial topology set including the number and location of offshore converter stations, turbine connections, and DC cable paths; screening feasible topology subsets that meet operational constraints through steady-state electrical characteristic analysis; constructing a dynamic cost evaluation model including time-series production simulation, simulating energy losses of the topology under various typical output scenarios throughout its life cycle, and generating a comprehensive evaluation value; and outputting the economically optimal topology based on the evaluation value. This invention systematically enumerates multi-location topology schemes, ensures technical feasibility through electrical verification, and accurately evaluates the full life cycle economics using a dynamic cost model, solving the problems of traditional design relying on experience, incomplete schemes, and coarse evaluation.

Description

Technical Field

[0001] This invention relates to the field of offshore wind power transmission planning technology, specifically to a method and system for optimizing the design of flexible DC grid-connected topology for offshore wind power in multi-landing scenarios. Background Technology

[0002] As offshore wind power develops towards deeper and larger scales, flexible DC transmission technology has become the mainstream technology for grid connection of offshore wind power due to its advantages such as long transmission distance, low loss, and strong reactive power regulation capability. When offshore wind farms need to transmit power to multiple onshore receiving-end converter stations located in different geographical locations at the same time, a multi-point grid connection scenario is formed. In this scenario, the topology design of the grid connection system faces great challenges. Designers need to make comprehensive decisions on multiple dimensions such as the number of offshore converter stations, site selection, AC collection network layout, and DC transmission corridor planning.

[0003] In existing technologies, the design of offshore wind power grid-connected topologies often adopts experience-based qualitative analysis methods or optimizes only for a single landing site scenario. Designers typically estimate the number of converter stations roughly based on the wind farm capacity and determine the site and transmission line route according to a simple geographical proximity principle. This design method has obvious shortcomings: on the one hand, the number of alternative solutions generated is limited and lacks systematicity, easily overlooking innovative topologies with potential advantages; on the other hand, the design process lacks rigorous verification of electrical safety constraints, which may lead to the discovery in the later construction stage that the design scheme does not meet the requirements for stable system operation, resulting in design rework and waste of resources. In addition, existing schemes often only focus on the initial investment cost when comparing schemes, ignoring the profound impact of dynamic power loss caused by the fluctuation characteristics of wind energy on the project's economics throughout the entire life cycle, making it difficult to select a topology with truly optimal long-term operating benefits. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for optimizing the design of flexible DC grid-connected topology for offshore wind power in multi-landing scenarios, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for optimizing the design of flexible DC grid-connected topology for offshore wind power in multi-landing-point scenarios, comprising the following steps: S1. Obtain the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. S2. Based on the basic parameters and grid connection location, construct the initial topology set of the offshore wind power flexible DC grid connection system. Each element in the initial topology set includes the planned number of offshore converter stations, the site selection of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. S3. Perform steady-state electrical characteristic analysis on each topology in the initial topology set, compare the analysis results with the operating constraints, and select a subset of feasible topologies that satisfy all operating constraints from the initial topology set. S4. Construct a dynamic cost assessment model. Substitute the topologies in the feasible topology subset into the model. The dynamic cost assessment model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology. Based on this, it generates a comprehensive evaluation value that characterizes the economic efficiency of the system throughout its entire life cycle. S5. Based on the comprehensive evaluation value, select the most economical topology from the feasible topology subset as the optimization design result for multi-landing scenarios.

[0006] As a preferred embodiment of the present invention, the step S2 of constructing the initial topology set specifically includes: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

[0007] As a preferred embodiment of the present invention, step S3 involves steady-state electrical characteristic analysis, specifically including: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is determined as a feasible topology that satisfies the operating constraints.

[0008] As a preferred technical solution of the present invention, the dynamic cost assessment model constructed in step S4 includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

[0009] As a preferred embodiment of the present invention, the dynamic cost assessment model generates a comprehensive evaluation value, specifically including: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

[0010] A flexible DC grid-connected topology optimization design system for offshore wind power in multi-landing-point scenarios, used to implement any one of the methods described above, comprising: The data acquisition module acquires the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. The topology generation module, connected to the data acquisition module, constructs an initial topology set for the offshore wind power flexible DC grid-connected system based on the received basic parameters and grid connection location. Each element in the initial topology set includes the planned number of offshore converter stations, the location of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. The feasibility verification module is connected to the topology generation module. It performs steady-state electrical characteristic analysis on each topology in the received initial topology set, compares the analysis results with the operating constraints, and selects a subset of feasible topologies that meet all operating constraints from the initial topology set. The economic evaluation module is connected to the feasibility verification module. It constructs a dynamic cost evaluation model, and substitutes the topologies in the feasible topology subset into the model. The dynamic cost evaluation model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology, and generates a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle. The optimization output module is connected to the economic evaluation module. Based on the received comprehensive evaluation value, the topology with the best economic efficiency is selected from the subset of feasible topologies and output as the optimization design result for multi-landing scenarios.

[0011] As a preferred embodiment of the present invention, when the topology generation module constructs the initial topology structure set, it performs the following actions: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

[0012] As a preferred embodiment of the present invention, the feasibility verification module performs the following actions when conducting steady-state electrical characteristic analysis: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is marked as a feasible topology that satisfies the operating constraints.

[0013] As a preferred technical solution of the present invention, the dynamic cost evaluation model constructed by the economic evaluation module includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

[0014] As a preferred embodiment of the present invention, when the economic evaluation module generates a comprehensive evaluation value, it performs the following actions: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs an initial topology set that includes the number of offshore converter stations, their locations, connection relationships, and DC cable paths. This enables the systematic enumeration and digital representation of various possible topological forms in multi-point grid connection scenarios, overcoming the shortcomings of traditional methods that rely on experience and result in incomplete exploration of the solution space.

[0016] 2. This invention introduces steady-state electrical characteristic analysis when screening feasible solutions, and accurately compares the power flow calculation results with the operating constraints. This can eliminate infeasible topologies that do not meet the requirements of voltage stability and thermal stability from the source, ensuring that every solution that enters the subsequent evaluation stage has technical safety and reliability, and effectively avoiding design iterations.

[0017] 3. This invention constructs a dynamic cost assessment model that includes an energy consumption analysis sub-model based on time-series production simulation. This model can accurately capture the dynamic power loss of the topology when dealing with actual wind speed fluctuations. It elevates the economic assessment from static and extensive investment estimation to dynamic and precise full life cycle simulation. This allows for the selection of optimized design schemes that may have slightly higher initial investment but are more economical and energy-efficient in long-term operation. This provides a scientific and refined decision-making basis for offshore wind power multi-point grid connection projects.

[0018] 4. The method and system of the present invention, through the organic combination of the above-mentioned technical means, form a complete closed loop from topology generation, feasibility verification to economic optimization, realize the automation and optimization of the design of flexible DC grid-connected topology structure for offshore wind power in multi-landing scenarios, significantly improve design efficiency and quality, and have extremely high engineering application value. Attached Figure Description

[0019] Figure 1This is an overall flowchart of the proposed method for optimizing the topology of flexible DC grid-connected offshore wind power in multi-landing-point scenarios. Figure 2 This is a structural framework diagram of the offshore wind power flexible DC grid connection topology optimization design system for multi-landing-point scenarios according to the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1

[0022] A method for optimizing the topology of flexible DC grid connection for offshore wind power in multi-landing scenarios includes the following steps: S1. Obtain the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. S2. Based on the basic parameters and grid connection location, construct the initial topology set of the offshore wind power flexible DC grid connection system. Each element in the initial topology set includes the planned number of offshore converter stations, the site selection of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. S3. Perform steady-state electrical characteristic analysis on each topology in the initial topology set, compare the analysis results with the operating constraints, and select a subset of feasible topologies that satisfy all operating constraints from the initial topology set. S4. Construct a dynamic cost assessment model. Substitute the topologies in the feasible topology subset into the model. The dynamic cost assessment model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology. Based on this, it generates a comprehensive evaluation value that characterizes the economic efficiency of the system throughout its entire life cycle. S5. Based on the comprehensive evaluation value, select the most economical topology from the feasible topology subset as the optimization design result for multi-landing scenarios.

[0023] Furthermore, step S2 involves constructing an initial set of topological structures, specifically including: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

[0024] Furthermore, step S3 involves steady-state electrical characteristic analysis, specifically including: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is determined as a feasible topology that satisfies the operating constraints.

[0025] Furthermore, the dynamic cost assessment model constructed in step S4 includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

[0026] Furthermore, the dynamic cost assessment model generates a comprehensive evaluation value, specifically including: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

[0027] A system for optimizing the topology of flexible DC grid connection for offshore wind power in multi-landing scenarios, comprising methods for achieving any of the above, including: The data acquisition module acquires the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. The topology generation module, connected to the data acquisition module, constructs an initial topology set for the offshore wind power flexible DC grid-connected system based on the received basic parameters and grid connection location. Each element in the initial topology set includes the planned number of offshore converter stations, the location of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. The feasibility verification module is connected to the topology generation module. It performs steady-state electrical characteristic analysis on each topology in the received initial topology set, compares the analysis results with the operating constraints, and selects a subset of feasible topologies that meet all operating constraints from the initial topology set. The economic evaluation module is connected to the feasibility verification module. It constructs a dynamic cost evaluation model, and substitutes the topologies in the feasible topology subset into the model. The dynamic cost evaluation model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology, and generates a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle. The optimization output module is connected to the economic evaluation module. Based on the received comprehensive evaluation value, the topology with the best economic efficiency is selected from the subset of feasible topologies and output as the optimization design result for multi-landing scenarios.

[0028] Furthermore, when the topology generation module constructs the initial set of topology structures, it performs the following actions: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

[0029] Furthermore, when performing steady-state electrical characteristic analysis, the feasibility verification module performs the following actions: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is marked as a feasible topology that satisfies the operating constraints.

[0030] Furthermore, the dynamic cost assessment model constructed by the economic assessment module includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

[0031] Furthermore, when the economic evaluation module generates the comprehensive evaluation value, it performs the following actions: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

[0032] Example 2

[0033] This embodiment uses a real offshore wind farm project as an application scenario to further illustrate the specific implementation process of the optimization design method in actual engineering, especially the refined operation of initial topology construction and feasibility verification in multi-point grid connection scenarios.

[0034] The offshore wind farm has a planned total installed capacity of 900 MW, with a site area of ​​approximately 150 square kilometers. It will be equipped with 60 wind turbine generators, each with a capacity of 15 MW. According to the power grid plan, the project needs to simultaneously transmit power to two onshore receiving-end converter stations, A and B, located in the coastal industrial area. The two grid connection locations are about 80 kilometers apart.

[0035] When constructing the initial topology set in step S2, it is not simply generated randomly, but systematically enumerated based on engineering experience and spatial analysis. Specifically, the topology generation module first selects three alternative schemes for the planned number of offshore converter stations: 1, 2, and 3, based on the total capacity of the wind farm of 900 MW and in combination with the mature voltage level and power module specifications of the existing flexible DC converter valve.

[0036] For the alternative scheme with two offshore converter stations, the topology generation module uses the precise geographical coordinates of 60 wind turbine generators as a basis and employs the K-means clustering algorithm for spatial partitioning. When the number of clusters is set to 2, the algorithm naturally divides the wind farm area into two clusters, east and west. The geometric center points of the two clusters are then determined as candidate sites for the two offshore converter stations, denoted as East and West Converter Stations, respectively. Subsequently, based on the principle of the shortest Euclidean distance between each wind turbine generator and these two candidate sites, the affiliation of each generator is determined, and a connection between the generators is planned accordingly. The radial or ring layout of the 35 kV AC collector lines of the corresponding converter stations is used. At the same time, based on the geographical coordinates of the East and West Hai-sea converter stations and the onshore stations A and B, the path optimization algorithm is used to avoid seabed obstacles and planned shipping channels to determine the preliminary paths of four DC submarine cables connecting East Hai-sea converter station to station A, East Hai-sea converter station to station B, West Hai-sea converter station to station A, and West Hai-sea converter station to station B. For alternative schemes with 1 and 3 converter stations, similar clustering, classification, and path planning operations are also performed to form an initial topology set containing multiple topological forms.

[0037] In step S3, during feasibility verification, the feasibility verification module uses professional power system simulation software to perform precise steady-state electrical characteristic analysis for each of the generated topologies. Taking a specific topology with two converter stations as an example, this structure is set so that the East Converter Station is directly connected to Station A via a DC cable, and the West Converter Station is directly connected to Station B via another DC cable. The simulation analysis is first conducted under extreme conditions of full-power output from the sea wind, and the voltage amplitude of each node in the AC collector network is found to be between 0.95 and 1.05. Within the acceptable range of PU, the current values ​​of the two DC cables are 1850 amps and 1780 amps respectively. These results are compared with the pre-obtained operating constraints. Among them, the DC current injected into the receiving-end converter stations of stations A and B must not exceed their thermal stability limit of 2000 amps. Since the current values ​​obtained from the simulation are all lower than 2000 amps and the voltage meets the requirements, this topology is judged to meet the basic operating constraints and is thus included in the feasible topology subset. For another topology, when the simulation finds that the current value of a certain DC cable will briefly rise to 2100 amps under the N-1 fault condition, exceeding the thermal stability limit, the structure is marked as infeasible and removed from the subsequent economic evaluation. Through this rigorous electrical simulation and threshold comparison, it is ensured that all topologies entering the next round of evaluation have technical safety and reliability.

[0038] This embodiment demonstrates how the method transforms abstract steps into concrete and executable engineering practices through refined operations based on actual project data. It can systematically generate and screen out diverse, technically feasible grid connection schemes, laying a solid and reliable foundation for subsequent economic optimization and avoiding unnecessary investment of evaluation resources in infeasible schemes.

[0039] Example 3

[0040] Based on the feasible topology subset selected in Example 2 above, this embodiment focuses on explaining the specific construction and operation mechanism of the dynamic cost assessment model in step S4, especially how to accurately capture energy loss throughout the entire life cycle through time-series production simulation, thereby generating a comprehensive evaluation value with decision-making guidance significance.

[0041] The core of the dynamic cost assessment model is an energy consumption analysis sub-model based on time-series production simulation. This sub-model simulates the power output process of the wind farm with extremely high time resolution. Specifically, the model has a built-in time-series database of measured wind speeds in the sea area over the past 20 years, and extracts three typical annual power output scenarios representing strong wind years, normal wind years, and light wind years. Each scenario contains second-level wind speed fluctuation data for 8760 hours throughout the year.

[0042] Taking a certain scheme in the feasible topology subset as an example, this scheme uses two offshore converter stations to supply power to stations A and B respectively through DC cables. The energy consumption analysis sub-model first reads the equipment parameters corresponding to this topology, including the conduction voltage drop characteristic curve of the converter valve, the no-load load loss parameters of the transformer, and the resistance value per unit length of the DC cable. Then, the model inputs the wind speed time series data of three typical years second by second to dynamically simulate the entire process of wind turbine generators converting wind energy into electrical energy and generate the corresponding power fluctuation curve.

[0043] In this process, the core function of the energy consumption analysis sub-model is demonstrated: it does not simply estimate the loss under rated power, but closely follows the power fluctuations every second and dynamically analyzes the power loss of each major device in the flexible DC transmission system. For example, when the wind speed increases suddenly and the output power rises rapidly, the model will accurately accumulate the loss under the on-state based on the real-time conduction current of the converter valve; when the power is stable, the continuous excitation loss and load loss of the transformer are taken into account; for DC cables, the model calculates the heat loss that changes with the square of the current based on the instantaneous value of the current in real time. Through this second-level dynamic tracking and accumulation, the model can finally output the total annual power loss value of the topology under three typical annual scenarios with high accuracy.

[0044] After obtaining accurate power loss values, the dynamic cost assessment model begins to generate a comprehensive evaluation value. First, the power loss values ​​under three typical annual scenarios are weighted and averaged to obtain the representative annual power loss. This is then multiplied by the 25-year life cycle and the local coal-fired benchmark electricity price of 0.45 yuan / kWh to convert it into the power loss cost over the entire life cycle. Next, based on the number of offshore converter platforms and the capacity specifications of converter valves in this topology, the model consults the equipment price database and determines the equipment procurement cost to be 1.28 billion yuan. Based on the length of the two DC cables, the selected ±320 kV voltage level and 2000 square millimeter cross-section, combined with the seabed geological conditions, the laying construction cost is determined to be 350 million yuan. At the same time, based on the historical operation and maintenance data of similar flexible DC projects and the equipment reliability model, the total operation and maintenance cost of planned overhauls and fault repairs over 25 years is estimated to be 220 million yuan. Finally, these four costs are summed to obtain the comprehensive evaluation value of 1.85 billion yuan for this topology.

[0045] After obtaining the comprehensive evaluation values ​​of all topologies in the feasible subset, the optimization output module sorts and compares them. The results show that an innovative topology using three small converter stations to supply power to stations A and B through a mesh DC grid, although its equipment procurement cost is slightly higher, has a better network structure, which significantly reduces the loss of heavily loaded lines and has higher redundancy, resulting in lower operation and maintenance costs. Its comprehensive evaluation value is 1.72 billion yuan, which is lower than the 1.85 billion yuan of the aforementioned scheme. Therefore, this scheme is determined to be the most economical topology and is output as the final optimization design result.

[0046] This embodiment introduces an energy consumption analysis sub-model based on time-series production simulation, elevating economic evaluation from static, extensive cost estimation to dynamic, precise full life-cycle simulation. The resulting technical effects are obvious: it can realistically reflect the energy efficiency performance of the topology in dealing with complex and ever-changing actual marine wind speed environments, thereby selecting optimized design schemes that not only have low initial investment but also are more economical and energy-efficient in long-term operation, providing a scientific and refined decision-making basis for offshore wind power multi-point grid connection projects.

[0047] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for optimizing the topology design of flexible DC grid-connected offshore wind power in multi-landing-point scenarios, characterized in that, Includes the following steps: S1. Obtain the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. S2. Based on the basic parameters and grid connection location, construct the initial topology set of the offshore wind power flexible DC grid connection system. Each element in the initial topology set includes the planned number of offshore converter stations, the site selection of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. S3. Perform steady-state electrical characteristic analysis on each topology in the initial topology set, compare the analysis results with the operating constraints, and select a subset of feasible topologies that satisfy all operating constraints from the initial topology set. S4. Construct a dynamic cost assessment model. Substitute the topologies in the feasible topology subset into the model. The dynamic cost assessment model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology. Based on this, it generates a comprehensive evaluation value that characterizes the economic efficiency of the system throughout its entire life cycle. S5. Based on the comprehensive evaluation value, select the most economical topology from the feasible topology subset as the optimization design result for multi-landing scenarios.

2. The method according to claim 1, characterized in that, The construction of the initial topology set in step S2 specifically includes: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

3. The method according to claim 1, characterized in that, The steady-state electrical characteristic analysis performed in step S3 specifically includes: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is determined as a feasible topology that satisfies the operating constraints.

4. The method according to claim 1, characterized in that, The dynamic cost assessment model constructed in step S4 includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

5. The method according to claim 4, characterized in that, The dynamic cost assessment model generates a comprehensive evaluation value, specifically including: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

6. A system for optimizing the topology of flexible DC grid connection for offshore wind power in multi-landing scenarios, used to implement the method of any one of claims 1-5, characterized in that, include: The data acquisition module acquires the basic parameters of the target offshore wind farm, the grid connection locations of multiple preset onshore receiving-end converter stations, and the operating constraints of each onshore receiving-end converter station. The topology generation module, connected to the data acquisition module, constructs an initial topology set for the offshore wind power flexible DC grid-connected system based on the received basic parameters and grid connection location. Each element in the initial topology set includes the planned number of offshore converter stations, the location of each offshore converter station, the connection relationship between each offshore converter station and the wind turbine generator, and the path of the DC submarine cable connecting each offshore converter station and each onshore receiving-end converter station. The feasibility verification module is connected to the topology generation module. It performs steady-state electrical characteristic analysis on each topology in the received initial topology set, compares the analysis results with the operating constraints, and selects a subset of feasible topologies that meet all operating constraints from the initial topology set. The economic evaluation module is connected to the feasibility verification module. It constructs a dynamic cost evaluation model, and substitutes the topologies in the feasible topology subset into the model. The dynamic cost evaluation model iteratively simulates the energy output and loss of the topology throughout its entire life cycle based on the equipment specifications, cable routes, and various preset typical annual output scenarios corresponding to the topology, and generates a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle. The optimization output module is connected to the economic evaluation module. Based on the received comprehensive evaluation value, the topology with the best economic efficiency is selected from the subset of feasible topologies and output as the optimization design result for multi-landing scenarios.

7. The system according to claim 6, characterized in that, When the topology generation module constructs the initial set of topology structures, it performs the following actions: Based on the total installed capacity of the wind farm and the sea area in the basic parameters, several alternative options for the number of offshore converter stations were selected. For each alternative, spatial clustering is performed based on the geographical coordinates of the wind turbine generators, and the cluster centers are determined as candidate sites for the offshore converter station. Based on the spatial relationship between the candidate sites and the wind turbine generators, the layout of the AC power collection lines connecting the two is planned. Based on the geographical information of candidate sites and the grid connection locations of multiple onshore receiving-end converter stations, a DC transmission corridor connecting the offshore converter station and each onshore receiving-end converter station is determined.

8. The system according to claim 6, characterized in that, When the feasibility verification module performs steady-state electrical characteristic analysis, it performs the following actions: Steady-state power flow analysis of the AC and DC systems is performed on the topology to obtain the voltage amplitude of each node on the AC side and the current value of each branch on the DC side. Compare the voltage amplitude with the allowable voltage range in the operating constraints, and compare the current value with the thermal stability limit value of the corresponding line in the operating constraints. When the voltage amplitude is within the allowable voltage range and the current value is below the thermal stability limit, the corresponding topology is marked as a feasible topology that satisfies the operating constraints.

9. The system according to claim 6, characterized in that, The dynamic cost assessment model constructed by the economic assessment module includes an energy consumption analysis sub-model based on time-series production simulation. The energy consumption analysis sub-model receives the equipment parameters and cable parameters of the topology, and combines them with wind speed time series data under various preset typical annual output scenarios to iteratively simulate the power fluctuation process of offshore wind farms under various scenarios, and simultaneously obtains the power loss values ​​of converter valves, transformers and cables when the flexible DC transmission system follows the power fluctuation.

10. The system according to claim 9, characterized in that, When the economic evaluation module generates the comprehensive evaluation value, it performs the following actions: The energy loss value output by the energy consumption analysis sub-model is converted into the energy loss cost over the entire life cycle. The equipment procurement cost is determined based on the specifications and quantity of the equipment in the topology. The laying cost is determined based on the path length, voltage level, and cross-section of the DC submarine cable. Based on historical operation and maintenance data and equipment reliability models, determine the operation and maintenance costs throughout the entire life cycle; The costs of power loss, equipment procurement, construction, and operation and maintenance are summed to generate a comprehensive evaluation value that characterizes the economic performance of the system throughout its entire life cycle.

Images