Power balance and substation capacity planning method based on flexible load resources

Abstract

This invention relates to the field of power regulation technology, specifically to a power balance and substation capacity planning method based on flexible load resources, comprising: (1) determining the load regulation capacity of various flexible load resources; (2) constructing power supply capacity demand models for midday and evening based on flexible load resources; and (3) finding the substation rated capacity with the minimum total cost during the planning period and the optimal dispatch plan for various flexible load resources during midday and evening, under the condition of meeting the power supply capacity demand during midday and evening. Deeply embedding flexible resources into the midday and evening power balance analysis not only alleviates the pressure of photovoltaic backfeeding and reduces peak load impact, but also comprehensively ensures the system operation safety by establishing a planning model that includes voltage, frequency, line and substation constraints; at the same time, the active adjustment of flexible resources promotes the efficient local consumption of new energy and reduces curtailment of solar power.

Description

Technical Field

[0001] This invention relates to the field of power regulation technology, and in particular to a power balance and substation capacity planning method based on flexible load resources. Background Technology

[0002] With the deepening of the construction of new power systems, the rapid development of high-proportion renewable energy grid connection and diversified flexible loads, new challenges have been posed to traditional power grid planning methods.

[0003] For a long time, power grid planning has mainly relied on load forecasting based on historical data, using static capacity-to-load ratio standards for substation capacity allocation. This method treats the load as a rigid, unadjustable input condition, with ensuring power supply reliability as its core objective. While this approach has played an important role in past development, it is no longer suitable for the highly uncertain operating environment on both the power source and load sides. In the current context, flexible resources such as distributed photovoltaic power, energy storage, adjustable industrial loads, commercial building air conditioning, and electric vehicle charging facilities are becoming increasingly abundant. These resources have the ability to respond to price signals or regulatory commands and can effectively participate in system regulation.

[0004] The peak solar power generation period at midday can easily lead to excessive backfeed power from the distribution network, increasing the pressure on the upstream grid for peak regulation and even causing curtailment of solar power. Meanwhile, during the evening peak load period, simply relying on building more substations to meet short-term peak demand results in low equipment utilization and poor investment efficiency. Related research focuses on the application of flexible resources in grid operation and planning, but mainly concentrates on resource aggregation modeling and demand response potential assessment, lacking a coordinated planning that integrates midday renewable energy consumption and evening load guarantee. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a power balance and substation capacity planning method based on flexible load resources, which aims to solve at least one of the above problems.

[0006] To achieve the above objectives, this invention provides a power balance and substation capacity planning method based on flexible load resources, the method being as follows:

[0007] (1) Determine the load regulation capacity of various flexible load resources;

[0008] (2) Based on flexible load resources, construct power supply capacity demand models for midday and evening respectively;

[0009] (3) Under the condition of meeting the power supply capacity demand during midday and evening, find the substation tr rated capacity with the minimum total cost value during the planning period. And the optimal allocation plan for various flexible load resources during midday and evening.

[0010] Furthermore, the specific model for the regional power grid's power supply capacity demand during midday is as follows:

[0011] ;

[0012] in, This indicates the power supply capacity demand of the regional power grid at noon. When the power supply capacity demand value is positive, it means that power needs to be sent down from the upper-level power grid. When the power supply capacity demand value is negative, it means that there is surplus power to be sent up. This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer at midday. This represents the load regulation capability of the i-th type of flexible load resource in the regional power grid.

[0013] Furthermore, the specific calculation model for the regional power grid's power supply capacity demand at night is as follows:

[0014] ;

[0015] in, This indicates the power supply capacity demand of the regional power grid at night; This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer during the evening. These are the loads of the regional power grid's energy storage system, commercial air conditioning load, industrial adjustable load, and electric vehicle load at night.

[0016] Furthermore, the specific formula for calculating the total cost during the planning period is as follows:

[0017] ;

[0018] in, This represents the total cost of the regional power grid during the planning period; This indicates the capacity investment cost of a newly built substation; This indicates that system operating costs, including network overhead and routine maintenance, are taken into account. This represents the cost incurred in load adjustment for flexible load resources.

[0019] Furthermore, the operating parameter constraints include: safety constraints on voltage and frequency, power constraints on line transmission, and load factor constraints on substations.

[0020] Furthermore, the specific safety constraints regarding voltage and frequency are as follows:

[0021] ;

[0022] ;

[0023] in, Number the nodes; The set of nodes in a regional power grid; , These are, respectively, moments and time sets; These are the lower and upper voltage limits for the node, respectively. This represents the voltage value of the i-th node at time t. Let be the frequency deviation of the i-th node at time t; This indicates the maximum limit of frequency deviation.

[0024] Furthermore, the power constraints for line transmission are as follows:

[0025] ;

[0026] in, This represents the transmission power of line l in the regional power grid at time t; This indicates the thermal stability limit value of the circuit; This represents the set of lines in a regional power grid.

[0027] Furthermore, the specific load factor constraints for each substation within the regional power grid are as follows:

[0028] ;

[0029] In the formula, This represents the power flowing through the substation tr at time t; This indicates the rated capacity of the substation (tr). This indicates the maximum permissible load rate of the substation tr. This represents the set of substations in a regional power grid.

[0030] Furthermore, the rated capacity of each substation (tr) in the regional power grid meets the following conditions:

[0031] ;

[0032] in, This represents the maximum permissible reverse overload factor for the substation. This represents the safety factor that takes into account uncertainty. This indicates the rated capacity of the substation tr, and this constraint prevents equipment overload caused by midday photovoltaic backfeed.

[0033] Furthermore, the rated capacity of each substation (tr) in the regional power grid meets the following conditions:

[0034] ;

[0035] in, This indicates the set capacity ratio.

[0036] By meticulously assessing the actual adjustability of flexible resources and incorporating them into planning, traditional substation expansion can be effectively replaced or delayed, significantly improving the economic efficiency of power grid investment. Secondly, deeply embedding flexible resources into midday and evening power balance analysis not only alleviates the pressure of photovoltaic backfeeding and reduces peak load impact, but also comprehensively ensures system operational safety by establishing a planning model that includes voltage, frequency, line, and substation constraints. Simultaneously, the proactive adjustment of flexible resources promotes efficient local consumption of new energy sources, reducing curtailment. This achieves closed-loop collaborative planning from resource assessment and multi-period balancing to capacity optimization, overcoming the problem of source-grid-load-storage separation and significantly enhancing the grid's adaptability to high-proportion renewable energy integration and overall resource utilization efficiency. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A flowchart of a power balancing and substation capacity planning method based on flexible load resources provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0040] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0041] This invention first calculates the adjustability of various flexible resources based on load characteristics and response intentions. Then, it constructs a power balance analysis method that integrates the adjustment role of flexible resources for two typical scenarios: midday renewable energy consumption and evening load peak. Finally, with the goal of optimal economic efficiency, it establishes a substation capacity optimization planning model that coordinates multiple safety operation constraints. Figure 1 A flowchart of a power balancing and substation capacity planning method based on flexible load resources provided in an embodiment of the present invention is shown. The method includes the following steps:

[0042] (1) Determine the load regulation capacity of various flexible load resources;

[0043] For flexible load resources such as industrial and commercial buildings and transportation charging facilities, resource types are classified and assigned participation coefficients based on their load characteristics and price sensitivity. The actual adjustable load is then calculated in conjunction with the maximum adjustable capacity. The calculation formula is as follows:

[0044] (1)

[0045] in, This represents the load regulation capability of the i-th type of flexible load resource. This represents the participation coefficient of the i-th type of flexible load resource in grid regulation. Let represent the maximum load value and minimum load value of the i-th type of flexible load resource, respectively.

[0046] (2) Based on flexible load resources, construct power supply capacity demand models for midday and evening respectively;

[0047] (21) Midday power supply demand model;

[0048] Define the boundary conditions for midday: The midday analysis time window is defined as 11:00 to 13:00, which typically corresponds to peak photovoltaic output and a relative low load. Considering that midday is not the peak load period for the entire day, the base load is taken as 40% of the maximum daily load of the corresponding regional power grid, i.e.:

[0049] (2)

[0050] In the formula, This indicates the base electrical load at midday; This represents the maximum value of the regional power grid's load throughout the day; This represents the load factor at midday, taken as 0.4.

[0051] Calculate midday photovoltaic output based on the installed capacity of the regional power grid, i.e.

[0052] (3)

[0053] In the formula, This indicates the photovoltaic output at midday; This indicates the photovoltaic installed capacity of the corresponding regional power grid; The photovoltaic output coefficient at midday is represented by 0.8.

[0054] A calculation model for the regional power grid's power supply capacity demand at midday is constructed, and the specific calculation formula is as follows:

[0055] (4)

[0056] In the formula, This indicates the power supply capacity demand of the regional power grid at noon. When the power supply capacity demand value is positive, it means that power needs to be sent down from the upper-level power grid. When the power supply capacity demand value is negative, it means that there is surplus power to be sent up. This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer at midday. This represents the load regulation capability of the i-th type of flexible load resource in the regional power grid.

[0057] In this embodiment of the invention, the flexible load resources in the regional power grid include four types: energy storage systems (such as electrochemical energy storage power stations), commercial air conditioning loads (such as commercial building air conditioning loads), industrial adjustable loads (such as controllable industrial motors, electric arc furnaces, etc.), and electric vehicle loads (such as charging pile clusters). The availability of these flexible load resources at midday is determined by the following parameters: energy storage systems (discharging is positive), commercial air conditioning loads (reduction is positive), industrial adjustable loads (reduction is positive), and electric vehicle loads (controlled reduction or transfer is positive) at midday. This indicates the regional power grid's power supply capacity demand value at midday. It is expressed as follows:

[0058] (5)

[0059] (22) Nighttime power supply demand model;

[0060] Define the boundary conditions for the evening: The evening analysis time window is defined as 19:00 to 21:00, which is the peak electricity consumption period of the day. The base load of the regional power grid is taken as the maximum value of the total daily load of the regional power grid, meaning the load factor for the evening is set to 1.

[0061] (6)

[0062] in, This indicates the basic electrical load of the regional power grid at night; This represents the maximum value of the regional power grid's load throughout the day; This represents the load factor for the evening, with a value of 1, and the photovoltaic output is 0 during the evening period. .

[0063] A calculation model for the power supply capacity demand of the regional power grid at night is constructed, and the specific calculation formula is as follows:

[0064] (7)

[0065] In the formula, This represents the power supply capacity demand of the regional power grid at night. This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer during the evening. These are the loads of the regional power grid's energy storage system, commercial air conditioning load, industrial adjustable load, and electric vehicle load at night.

[0066] (3) Under the condition of meeting the power supply capacity demand during midday and evening, find the substation tr rated capacity with the minimum total cost value during the planning period. And the optimal allocation plan for various flexible load resources during midday and evening.

[0067] The objective is to minimize the present value of total costs over the planning period. The costs mainly include:

[0068] (8)

[0069] in, This represents the total cost of the regional power grid during the planning period; This indicates the capacity investment cost of a newly built substation; This indicates that system operating costs, including network overhead and routine maintenance, are taken into account. This refers to the cost incurred in load regulation of flexible load resources, such as the fees or subsidies payable to users for load regulation of flexible load resources.

[0070] In this embodiment of the invention, the operating parameter constraints include: safety constraints on voltage and frequency, power constraints on line transmission, and load factor constraints on substations. The constraints are specifically represented as follows:

[0071] (31) Safety constraints on voltage and frequency;

[0072] (9)

[0073] (10)

[0074] in, Number the nodes; , These are, respectively, moments and time sets; These are the lower and upper voltage limits for the node, respectively. This represents the voltage value of the i-th node at time t. Let be the frequency deviation of the i-th node at time t; Indicates the maximum limit of frequency deviation; It is a set of nodes in a regional power grid, including generator nodes, substation nodes, network branch nodes, load nodes, etc.

[0075] (32) Power constraints for line transmission:

[0076] (11)

[0077] in, This represents the transmission power of line l in the regional power grid at time t; This indicates the thermal stability limit value of the circuit; This represents the set of lines in a regional power grid.

[0078] (33) Load factor constraints of each substation within the regional power grid:

[0079] (12)

[0080] In the formula, This represents the power flowing through the substation tr at time t; This indicates the rated capacity of the substation (tr). This represents the maximum permissible load factor (tr) of the substation, typically taken as 0.8. This represents the set of substations in a regional power grid.

[0081] (34) The capacity of the regional power grid after planning must meet the power supply demand at noon and in the evening.

[0082] At midday, ensure that after the peak generation of solar power and the mobilization of flexible resources, the capacity of all substations (including newly added substations) in the regional power grid can safely handle the maximum possible reverse power or residual load, as shown below:

[0083] (13)

[0084] in, This represents the maximum permissible reverse overload factor for the substation. This represents the safety factor that takes into account uncertainty. This indicates the rated capacity of the substation tr, and this constraint prevents equipment overload caused by midday photovoltaic backfeed.

[0085] In the evening, after peak load and the deployment of flexible load resources, the capacity of all substations (including newly added substations) in the regional power grid must meet the maximum forward power supply demand, i.e., the capacity-to-load ratio requirement, as shown below:

[0086] (14)

[0087] In the formula, This indicates the set capacity ratio.

[0088] Solving the above mixed-integer linear programming model yields the optimal solution set, including:

[0089] ① Planning and decision-making: Optimal rated capacity of each substation ;

[0090] ② Operation strategy: The optimal participation coefficient of each flexible load resource at noon and in the evening, that is, the load adjustment amount of flexible load resources at noon and in the evening.

[0091] The power balance and substation capacity planning method based on flexible load resources provided by this invention has the following beneficial technical effects:

[0092] First, by meticulously assessing the actual adjustability of flexible resources and incorporating it into planning, traditional substation expansion can be effectively replaced or delayed, significantly improving the economic efficiency of grid investment. Second, deeply embedding flexible resources into midday and evening power balance analysis not only alleviates the pressure of photovoltaic backfeeding and reduces peak load impact, but also comprehensively ensures system operational safety by establishing a planning model that includes voltage, frequency, line, and substation constraints. Simultaneously, the proactive adjustment of flexible resources promotes efficient local consumption of new energy, reducing curtailment. This achieves closed-loop collaborative planning from resource assessment and multi-period balancing to capacity optimization, overcoming the problem of source-grid-load-storage separation, and significantly enhancing the grid's adaptability to high-proportion renewable energy integration and overall resource utilization efficiency.

[0093] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity. Any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A method for power balance and substation capacity planning based on flexible load resources, characterized by, The method is as follows: (1) Determine the load regulation capacity of various flexible load resources; (2) Based on flexible load resources, construct power supply capacity demand models for midday and evening respectively; (3) Under the condition of meeting the power supply capacity demand during midday and evening, find the substation tr rated capacity with the minimum total cost value during the planning period. And the optimal allocation plan for various flexible load resources during midday and evening.

2. The power balancing and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, The specific model for the regional power grid's power supply capacity demand during midday is as follows: ； in, This indicates the power supply capacity demand of the regional power grid at noon. When the power supply capacity demand value is positive, it means that power needs to be sent down from the upper-level power grid. When the power supply capacity demand value is negative, it means that there is surplus power to be sent up. This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer at midday. This represents the load regulation capability of the i-th type of flexible load resource in the regional power grid.

3. The power balancing and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, The specific calculation model for the regional power grid's power supply capacity demand at night is as follows: ； in, This indicates the power supply capacity demand of the regional power grid at night; This indicates the electrical load supplied to the regional power grid by the upstream power grid through the main transformer during the evening. These are the loads of the regional power grid's energy storage system, commercial air conditioning load, industrial adjustable load, and electric vehicle load at night.

4. The power balance and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, The formula for calculating the total cost during the planning period is as follows: ； in, This represents the total cost of the regional power grid during the planning period; This indicates the capacity investment cost of a newly built substation; This indicates that system operating costs, including network overhead and routine maintenance, are taken into account. This represents the cost incurred in load adjustment for flexible load resources.

5. The power balancing and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, Operating parameter constraints include: safety constraints on voltage and frequency, power constraints on line transmission, and load factor constraints on substations.

6. The power balancing and substation capacity planning method based on flexible load resources according to claim 5, characterized in that, The specific safety constraints for voltage and frequency are as follows: ； ； in, Number the nodes; The set of nodes in a regional power grid; , These are, respectively, moments and time sets; These are the lower and upper voltage limits for the node, respectively. This represents the voltage value of the i-th node at time t. Let be the frequency deviation of the i-th node at time t; This indicates the maximum limit of frequency deviation.

7. The power balancing and substation capacity planning method based on flexible load resources according to claim 5, characterized in that, The power constraints for line transmission are as follows: ； in, This represents the transmission power of line l in the regional power grid at time t; This indicates the thermal stability limit value of the circuit; This represents the set of lines in a regional power grid.

8. The power balancing and substation capacity planning method based on flexible load resources according to claim 5, characterized in that, The specific load factor constraints for each substation within the regional power grid are as follows: ； In the formula, This represents the power flowing through the substation tr at time t; This indicates the rated capacity of the substation (tr). This indicates the maximum allowable load rate of the substation tr. This represents the set of substations in a regional power grid.

9. The power balancing and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, The rated capacity of each substation (tr) in the regional power grid meets the following conditions: ； in, This represents the maximum permissible reverse overload factor for the substation. This represents the safety factor that takes into account uncertainty. This indicates the rated capacity of the substation tr, and this constraint prevents equipment overload caused by midday photovoltaic backfeed.

10. The power balancing and substation capacity planning method based on flexible load resources according to claim 1, characterized in that, The rated capacity of each substation (tr) in the regional power grid must meet the following conditions: ； in, This indicates the set capacity ratio.

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