AC / DC hybrid power grid planning method considering AC / DC line operation characteristics

Abstract

The invention relates to an AC-DC hybrid power grid planning method considering AC-DC line operation characteristics, which is used for coordinating modeling requirements of short-time AC-DC line characteristics and power grid planning long-term economy requirements, improving new energy consumption capability and reducing power transmission channel construction cost. The method specifically comprises the following steps: establishing an AC / DC hybrid power grid planning model based on the investment cost of a to-be-selected AC line and a to-be-selected DC line, the starting cost of a coal power unit and a gas power unit, the operation cost of the coal power unit and the gas power unit in T analysis time periods of a selected day, and the penalty cost of load shedding and new energy power abandoning; determining a running direct-current and alternating-current line, a working coal power unit, a working gas power unit, a load shedding demand and a new energy demand by enabling the alternating-current and direct-current hybrid power grid planning model to obtain a minimum value; the planning model considers the application of an alternating current line dynamic capacity increasing technology.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning, and more particularly to a method for planning an AC / DC hybrid power grid taking into account the operating characteristics of AC / DC lines. Background Art

[0002] With the continued increase in renewable energy penetration, AC / DC hybrid power grids have become the core vehicle for achieving cross-regional power integration and renewable energy consumption. However, the high volatility of renewable energy output and the widening load peak-to-valley range make transmission channels prone to capacity bottlenecks during peak hours and underutilization during off-peak hours.

[0003] Traditional grid planning methods rely primarily on static line capacity parameters, resulting in over-reliance on newly built lines and an inability to fully utilize the potential transmission capacity of these lines, leading to wasted investment and resource misallocation. Dynamic capacity expansion technology, through real-time monitoring of line environmental parameters, can improve short-term transmission capacity, providing an effective means of alleviating transmission bottlenecks during peak load periods. However, the time-varying nature of this technology conflicts with the long-term nature of grid planning. Failure to fully consider the available timeframe and duration of dynamic capacity expansion, as well as its synergistic relationship with DC lines, during the planning phase can lead to overly conservative or insufficiently robust planning solutions.

[0004] In addition, the lack of constraints on DC line utilization can easily lead to inefficient investment and construction of DC transmission channels; and the verification system lacks a systematic assessment of operating conditions and multi-dimensional uncertainties, making it difficult to quantify the long-term comprehensive benefits of the planning scheme. Summary of the Invention

[0005] In view of this, in order to at least partially solve the above-mentioned technical problems, the present invention provides an AC / DC hybrid power grid planning method taking into account the operating characteristics of AC / DC lines. The method aims to coordinate the modeling requirements of short-term AC / DC line characteristics with the long-term economic requirements of power grid planning, while improving the new energy absorption capacity and reducing the construction cost of transmission channels, providing technical support for AC / DC hybrid power grid planning.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present application provides a method for planning an AC / DC hybrid power grid that considers the operating characteristics of AC / DC lines, the steps comprising:

[0008] Consider the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC Construct an AC line model based on the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied;

[0009] Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established;

[0010] With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined.

[0011] Preferably, the new energy sources include photovoltaic, wind power and hydropower.

[0012] Preferably, an AC / DC hybrid power grid planning model is established based on the AC line model and the DC line model, including:

[0013] An AC / DC hybrid power grid planning model is established based on the investment costs of the candidate AC and DC lines in the AC and DC line models, the startup costs of coal-fired and gas-fired power units, the operating costs of coal-fired and gas-fired power units in T analysis periods on selected days, and the penalty costs of load shedding and renewable energy power abandonment.

[0014] Preferably, the AC line model allows the line transmission power to exceed the capacity within a set period of time, and the AC line using dynamic capacity expansion runs for another x hours without exceeding the original transmission capacity after running for x hours, so that the line temperature returns to normal.

[0015] In a second aspect, the present application provides an AC / DC hybrid power grid planning system that considers the operating characteristics of AC / DC lines, including a planning module:

[0016] The planning module is configured to take into account the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC Construct an AC line model based on the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied;

[0017] Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established;

[0018] With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined.

[0019] In a third aspect, the present application provides a method for verifying an AC / DC hybrid power grid that takes into account the operating characteristics of AC / DC lines. The method comprises:

[0020] Construct a time-series power balance analysis model for T' analysis periods, including the startup costs of coal-fired and gas-fired units, the operating costs of coal-fired and gas-fired units, and the penalty costs of load shedding and renewable energy curtailment.

[0021] By minimizing the time-series power balance analysis model, the operating coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined;

[0022] Based on the working coal-fired power units and gas-fired power units, load shedding demand and new energy demand, combined with the DC / AC lines determined based on the planning method described in any one of claims 1-3, simulation is performed to verify whether the adoption of dynamic capacity expansion technology can improve the new energy absorption capacity.

[0023] Preferably, the verification indicators used include system power shortage probability, system expected power shortage amount, system wind curtailment rate, and system solar curtailment rate.

[0024] As a preference, the simulation uses the Monte Carlo method to simulate uncertainties, and the analysis period is the whole year.

[0025] The AC / DC hybrid power grid planning method that takes into account the operating characteristics of AC / DC lines provided by the present invention has the following beneficial technical effects compared with the existing technology:

[0026] (1) By integrating the time-varying characteristics of dynamic capacity expansion into a collaborative modeling approach for AC and DC lines, the contradiction between long-term economic efficiency and operational safety in grid planning is effectively reconciled. This approach captures the time-varying characteristics and recovery mechanisms of line capacity caused by dynamic capacity expansion, enabling planning schemes to proactively utilize the short-term overload capacity of AC lines while mitigating low-return investments by constraining the minimum utilization of DC lines.

[0027] (2) A hybrid AC / DC grid planning model was designed with special consideration for the operational characteristics of AC / DC lines, effectively coordinating the differentiated operational requirements of AC / DC lines. By constraining unit operation and network transmission capacity, this model ensures that the planning scheme meets the safety requirements for coordinated AC / DC system operation while improving the capacity to accommodate new energy.

[0028] (3) A power balance verification system for AC / DC hybrid power grid planning schemes was constructed to provide a multi-dimensional quantitative evaluation benchmark for the planning schemes. Production simulation was used to verify the planning schemes’ effectiveness in alleviating transmission bottlenecks. The Monte Carlo method was combined to simulate equipment failures and renewable energy fluctuations, and key indicators such as the system power outage probability, expected power outage, and wind and solar power curtailment rates were quantitatively evaluated. This provided credibility verification for the engineering application of the planning method, ensuring that the planning schemes were both economical and robust. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0030] Figure 1 Schematic diagram of the execution flow of the AC / DC hybrid power grid planning method of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] The following description sets forth many specific details to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0033] First, we provide an explanation of the meaning of the parameters involved in this case, as shown in Table 1;

[0034] Table 1

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

[0041]

[0042] Typical days are selected based on the following factors: 1. Date type: load patterns vary between weekdays, weekends, and holidays; 2. Seasonal factors: source-load characteristics vary in different seasons, and some extreme weather scenarios also need to be considered; 3. Load characteristics: dates with load levels close to the annual average or a specific peak value are usually selected.

[0043] AC / DC transmission line characteristic modeling is a fundamental part of power grid planning methods. Its core goal is to construct a mathematical model that can accurately characterize the electrical characteristics, operating constraints and action mechanisms of AC / DC lines.

[0044] Traditional grid planning methods typically use static line capacity parameters and fail to fully consider the time-varying current-carrying capacity enhancement effects of dynamic capacity expansion technology, making it difficult for planning schemes to adapt to the flexible adjustment needs in scenarios with high penetration of new energy. In particular, in AC / DC hybrid power grids, the physical characteristics of the two types of lines differ significantly—AC lines are subject to power angle stability constraints, while the transmission capacity of DC lines is closely related to the parameters and control strategies of the converter equipment. This heterogeneous characteristic results in significant spatial differences in the application effectiveness of dynamic capacity expansion technology. Few existing modeling methods can effectively characterize the continuous time-varying characteristics of line capacity caused by dynamic capacity expansion technology, making it difficult to achieve optimal coordination between the economy and safety of planning schemes.

[0045] Based on this, this disclosure describes the effect of dynamic capacity expansion technology in the AC line model as allowing the line's transmission power to exceed the designed capacity within a certain period. For the process of naturally cooling the line after applying dynamic capacity expansion, the model design describes the following: After x hours of operation in the expanded state, the line must then operate for x hours without exceeding the original transmission capacity to restore the line temperature to normal. This approach constructs an AC / DC line model that incorporates dynamic capacity expansion parameters, effectively coupling the time-varying characteristics of line transmission capacity with the long-term economic objectives of grid planning, providing precise physical constraint boundaries for subsequent planning optimization.

[0046] Specifically, this application considers the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC The AC line model is constructed by comparing the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied. The forms are shown in equations (1)-(11).

[0047]

[0048] According to the requirements of the planned DC line, constraints are added to ensure that its utilization rate meets the established requirements. The DC line model is shown in Equations (12)-(16).

[0049]

[0050]

[0051] Furthermore, in one embodiment, an AC / DC hybrid power grid planning model is established based on the investment costs of the selected AC lines and DC lines in the AC line model and the DC line model, the startup costs of the coal-fired power units and the gas-fired power units, and the operating costs of the coal-fired power units and the gas-fired power units in T analysis periods on individually selected days, and the penalty costs of load shedding and renewable energy power abandonment.

[0052] With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired power units and gas-fired power units, load shedding requirements and new energy requirements are determined.

[0053] Among them, the objective function of the AC / DC hybrid power grid planning model considering the application of line dynamic capacity expansion technology is shown in formula (17):

[0054]

[0055] In this embodiment, the constraints of the coal-fired power unit are shown in equations (18)-(24):

[0056]

[0057]

[0058] The constraints of the gas-fired generator set are shown in equations (25)-(31):

[0059] The constraints of the hydropower unit are shown in equations (32)-(35):

[0060] The constraints of the new energy generator set are shown in equations (36)-(39):

[0061]

[0062] The power balance and transmission constraints at the system level are shown in Equations (40) and (41):

[0063]

[0064] Finally, power balance analysis and production simulation verification are carried out.

[0065] In one embodiment, after completing the construction of the AC / DC hybrid power grid planning model and the solution of the scheme considering the dynamic capacity expansion of the line, it is necessary to conduct power balance analysis and production simulation verification on the planning scheme. In order to save computing power, the planning model adopts several typical day simulation methods, and the production simulation process can realize simulation verification of long-term continuous time scale based on the solution results of the planning model. Based on the power installed capacity, load demand characteristics and line transmission capacity constraints after dynamic capacity expansion in the planning scheme, a time-series power balance analysis model is established. The balance analysis model can be described as shown in formulas (42)-(43). Among them, the constraints covered in formula (43) are consistent with the power balance model at the time scale level, and a continuous long period is used as the overall analysis period range.

[0066]

[0067]

[0068] This application incorporates time-varying transmission limit parameters for dynamic capacity expansion lines, taking into account typical daily load curves across different seasons, renewable energy output fluctuations, and the DC system's rapid power regulation capabilities. This approach verifies the power supply and demand balance margin of the planning scheme under 8,760 hours of annual operation. The application focuses on verifying the capacity release effect of dynamic capacity expansion technology during critical scenarios, such as peak load periods and periods of high renewable energy generation, and quantitatively analyzes its mechanism for alleviating transmission bottlenecks and improving renewable energy absorption capacity.

[0069] The Monte Carlo method is used to simulate multidimensional uncertainties such as equipment failures and fluctuations in renewable energy output. Within the framework of an AC / DC hybrid power grid, the technical and economic feasibility of the planning scheme is evaluated through time series simulation. Verification indicators include, but are not limited to, the probability of system power outages, the expected power outage, and the wind and solar power curtailment rates, as shown in Equations (44)-(47).

[0070]

[0071] In summary, those skilled in the art can derive the following execution flow of the AC / DC hybrid power grid planning method and verification method: Figure 1 As shown:

[0072] 1) Build an AC / DC line model that takes operational characteristics into account;

[0073] 2) Construct an AC / DC hybrid power grid planning model that takes into account the line operation characteristics;

[0074] 3) Solve the planning model to obtain a planning scheme, perform power balance analysis on the planning scheme, and quantify the effect of the planning scheme on alleviating transmission bottlenecks;

[0075] 4) Monte Carlo method is used to simulate multi-dimensional uncertainties and the technical and economic feasibility of the planning scheme is evaluated through full-year time series simulation;

[0076] 5) Calculate production simulation indicators and quantitatively verify the comprehensive benefits of the planning scheme.

[0077] Through the description of the above embodiments, those skilled in the art can clearly understand that a corresponding system can be implemented according to the method disclosed in the present invention. For example, an AC / DC hybrid power grid planning system considering the operating characteristics of AC / DC lines includes a planning module. The planning module is configured to consider the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC Construct an AC line model based on the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied;

[0078] Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established;

[0079] With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined.

[0080] Accordingly, those skilled in the art can also obtain an AC / DC hybrid power grid verification system that takes into account the operating characteristics of AC / DC lines.

[0081] Through the above description of the embodiments, those skilled in the art will clearly understand that the disclosed methods and systems can be implemented using software plus necessary general-purpose hardware. Of course, they can also be implemented using dedicated hardware, including application-specific integrated circuits, dedicated CPUs, dedicated memories, and dedicated components. Generally speaking, any function performed by a computer program can be easily implemented using corresponding hardware. Moreover, the specific hardware structures used to implement the same function can also be diverse, such as analog circuits, digital circuits, or dedicated circuits. However, for the present disclosure, software implementation is often the preferred embodiment.

[0082] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0083] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for planning an AC / DC hybrid power grid taking into account the operating characteristics of AC / DC lines, characterized in that: include: Consider the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC Construct an AC line model based on the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied; Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established; With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined.

2. The AC / DC hybrid power grid planning method according to claim 1, characterized in that: New energy includes photovoltaics, wind power and hydropower.

3. The AC / DC hybrid power grid planning method according to claim 1, characterized in that: Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established, including: An AC / DC hybrid power grid planning model is established based on the investment costs of the candidate AC and DC lines in the AC and DC line models, the startup costs of coal-fired and gas-fired power units, the operating costs of coal-fired and gas-fired power units in T analysis periods on selected days, and the penalty costs of load shedding and renewable energy power abandonment.

4. The AC / DC hybrid power grid planning method according to claim 1, characterized in that: The AC line model allows the line transmission power to exceed the capacity within a set period of time, and after the AC line using dynamic capacity increase runs for x hours, it runs for another x hours without exceeding the original transmission capacity, so that the line temperature returns to normal.

5. An AC / DC hybrid power grid planning system considering the operating characteristics of AC / DC lines, characterized by: Planning modules include: The planning module is configured to take into account the AC line i AC Transmission power limit without and with dynamic capacity expansion technology, AC line i AC The maximum continuous application time limit of dynamic capacity expansion technology and AC line i AC Construct an AC line model based on the distance between the jth period in a typical day m and the time when the dynamic capacity increase technology was last applied; Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established; With the goal of minimizing the AC / DC hybrid power grid planning model, the operating DC / AC lines, working coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined.

6. The AC / DC hybrid power grid planning system according to claim 5, characterized in that: New energy includes photovoltaics, wind power and hydropower.

7. The AC / DC hybrid power grid planning system according to claim 5, characterized in that: Based on the AC line model and the DC line model, an AC / DC hybrid power grid planning model is established, including: An AC / DC hybrid power grid planning model is established based on the investment costs of the candidate AC and DC lines in the AC and DC line models, the startup costs of coal-fired and gas-fired power units, the operating costs of coal-fired and gas-fired power units in T analysis periods on selected days, and the penalty costs of load shedding and renewable energy power abandonment.

8. A method for verifying an AC / DC hybrid power grid taking into account the operating characteristics of AC / DC lines, characterized in that: Methods include: Construct a time-series power balance analysis model for T' analysis periods, including the startup costs of coal-fired and gas-fired units, the operating costs of coal-fired and gas-fired units, and the penalty costs of load shedding and renewable energy curtailment. By minimizing the time-series power balance analysis model, the operating coal-fired and gas-fired power units, load shedding requirements, and new energy requirements are determined; Based on the working coal-fired power units and gas-fired power units, load shedding demand and new energy demand, combined with the DC and AC lines determined by the AC / DC hybrid power grid planning method considering the operating characteristics of AC and DC lines as described in any of claims 1-4, simulation verification is conducted to verify whether the adoption of dynamic capacity expansion technology can improve the new energy absorption capacity.

9. The AC / DC hybrid power grid verification method according to claim 8, characterized in that: The verification indicators used include system power shortage probability, system expected power shortage, system wind power abandonment rate, and system solar power abandonment rate.

10. The AC / DC hybrid power grid verification method according to claim 8, characterized in that: The simulation uses the Monte Carlo method to simulate uncertainties, and the analysis period is the whole year.

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