220KV key substation identification method based on supply guarantee demand constraint

Abstract

The invention relates to a 220 kilovolt key substation identification method based on supply guarantee demand constraint, and relates to the technical field of power grids. According to the method, the proportion of important loads supplied by the transformer substation to the rated capacity of the transformer substation, the load rate of the transformer substation after the maximum-capacity main transformer is N-1 at the moment of the large load of the transformer substation, and the ratio of the loads which cannot be transferred to the rated capacity of the transformer substation are comprehensively considered; a target function is constructed based on the indexes according to the ratio of the output power of a power supply accessed through the voltage level of 110 kilovolt and below to the important load supplied by a 220 kilovolt transformer substation in a transformer substation supply area and the ratio of the sum of the power flowing out of a transformer substation node to the sum of the power flowing into the transformer substation node. The 220KV transformer substations are sequenced according to the objective function value, so that the importance degree of the 220KV transformer substations is obtained, reinforcement of weak links of a power grid by power grid planning is facilitated, and the method has very important engineering practice and power grid planning operation significance.

Description

Technical Field

[0001] The present application relates to the field of power grid technology, and in particular to a method for identifying 220 kV key substations based on supply guarantee demand constraints. Background Art

[0002] The collapse of important substations in the power grid will cause a sharp decline in the connectivity of the power grid. Serious failures in important substations may cause cascading failures, and eventually lead to power angle instability in the entire system. The importance of substations is not only related to the topological structure of the power grid, but also to factors such as power grid flow, power supply and load. Therefore, it is urgent to identify key substations in the power grid and accurately identify important nodes in the power grid, which will help power grid companies implement differentiated management and strengthen the operation and maintenance of important substations in advance, so as to ensure safe and stable operation of the power grid and reliable power supply.

[0003] 220 kV is an important main grid voltage level for regional power grid power supply, and is also an important channel for power mutual support between regional power grids. Therefore, it is necessary to consider the upper main supply site of the 110 kV important substation collection as the key 220 kV important substation collection, so that the 220 kV power grid can meet the needs of safe and reliable power supply. Summary of the invention

[0004] The purpose of this application is to provide a 220 kV key substation identification method based on supply guarantee demand constraints, which can effectively identify the importance of 220 kV substations in the power grid.

[0005] In order to achieve the above object, the present invention provides a 220 kV key substation identification method based on supply guarantee demand constraints, the method comprising the following steps:

[0006] S1: Calculate the proportion of the important load supplied by the substation to the rated capacity of the substation α;

[0007] S2: Calculate the substation load rate β after the maximum capacity main transformer N-1 at the time of high load;

[0008] S3: Calculate the ratio δ between the output power of the power source connected to the supply area of ​​220 kV substation at a voltage level of 110 kV or below and the important load supplied by the 220 kV substation;

[0009] S4: Calculate the ratio ε of the sum of the power flowing out of the substation node to the sum of the power flowing into the substation node;

[0010] S5: Count the 110 kV load and 10 kV load that cannot be transferred through the 110 kV transmission line under the 220 kV substation, and calculate the ratio η between the non-transferable load and the rated capacity of the substation;

[0011] S6: Based on the supply guarantee demand, construct the power balance constraints that all 220 kV substations need to meet;

[0012] S7: Establish an objective function F and calculate the objective function value;

[0013] S8: Sort the objective function values ​​of different 220 kV substations from large to small. The substation with a larger objective function value is more important in the power grid and is a more critical substation.

[0014] In an optional implementation, in S1, the proportion α of the important load supplied by the substation to the rated capacity of the substation is calculated, as shown in the following formula:

[0015]

[0016] Where P imp,load Indicates the important load supplied by the substation, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

[0017] In an optional implementation, in S2, the substation load rate β after the maximum capacity main transformer N-1 at the time of high load is calculated, as shown in the following formula:

[0018]

[0019] Where P max,load represents the load of the substation at the maximum load moment, max{S1,S2,…,S i} represents the maximum capacity of the main transformer of the substation, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

[0020] In an optional implementation, in S3, the ratio δ between the output power of power sources connected to the supply area of ​​the 220 kV substation at a voltage level of 110 kV or lower and the important load supplied by the 220 kV substation is calculated, as shown in the following formula:

[0021]

[0022] Where P resource It indicates the output power of the power supply connected to the supply area of ​​220 kV substation through the voltage level of 110 kV and below, P imp,load Indicates the important loads supplied by the substation.

[0023] In an optional embodiment, in S3, the power supply output power P resource , as shown below:

[0024] P resource =λ termal S termal +λ ydro S ydro +λ RES S RES

[0025] In the formula, λ thermal Indicates the output coefficient of thermal power unit, S thermal represents the installed capacity of thermal power plant, λ hydro Indicates the output coefficient of the hydropower unit, S hydro represents the installed capacity of the hydropower generator, λ RES Represents the output coefficient of new energy, S RES Represents the installed capacity of new energy.

[0026] In an optional implementation, in S4, the ratio ε of the sum of the power flowing out of the substation node to the sum of the power flowing into the substation node is calculated, as shown in the following formula:

[0027]

[0028] When the sum of the power flowing out of the substation node is 0, let P out,sub =0.1P in,sub , where P in,sub Represents the sum of the power flowing into the substation node, P out,sub Represents the sum of the powers flowing out of the substation node.

[0029] In an optional implementation, in S4, the sum of the power flowing out of the substation node and the sum of the power flowing into the substation node are calculated, as shown in the following formula:

[0030]

[0031] N=N1+N2

[0032] Where P j,line,in represents the power flowing into the substation node from the jth transmission line, N1 represents the number of transmission lines through which the power flows into the substation node; P k,line,out represents the power flowing out of the substation node on the kth transmission line, N2 represents the number of transmission lines through which the power flows out of the substation node; N represents the number of transmission lines between the 220 kV substation and the surrounding 220 kV substations.

[0033] In an optional implementation, in S5, the ratio η between the non-transferable load and the rated capacity of the substation is calculated as shown in the following formula:

[0034]

[0035] Where P untransfer,110 It represents the 110 kV load that cannot be transferred through the 110 kV transmission line, P untransfer,10 Indicates the 10 kV load that cannot be transferred, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

[0036] In an optional implementation, in S6, a power balance constraint that needs to be satisfied by all 220 kV substations is constructed, as shown in the following formula:

[0037] P in,sub +P resource =P load +P ESS +P out,sub

[0038] Where P in,sub Represents the sum of the power flowing into the substation node, P resource It indicates the output power of the power supply connected to the supply area of ​​220 kV substation through the voltage level of 110 kV and below, P load Indicates the load within the power supply area of ​​220 kV substation; P ESS Indicates the energy storage power in the power supply area of ​​220 kV substation, P out,sub Represents the sum of the powers flowing out of the substation node.

[0039] In an optional implementation, in S7, the objective function F is as shown in the following formula:

[0040]

[0041] This method comprehensively considers the proportion of important loads supplied by the substation to the rated capacity of the substation, the substation load rate after the maximum capacity main transformer N-1 at the time of high load, the ratio between the non-transferable load and the rated capacity of the substation, the ratio between the output power of the power supply connected through the voltage level of 110 kV and below in the substation supply area and the important load supplied by the 220 kV substation, and the ratio between the sum of the power flowing out of the substation node and the sum of the power flowing into the substation node, and constructs the objective function based on the above indicators. The 220 kV substation is sorted according to the objective function value, thereby obtaining the importance of the 220 kV substation.

[0042] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 A flow chart of a 220 kV key substation identification method based on supply guarantee demand constraints provided in an embodiment of the present application.

[0045] Figure 2 The power flow diagram of the regional power grid under the large-scale mode in summer 2024 is given. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0047] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0048] Please refer to Figure 1 This embodiment provides a 220 kV key substation identification method based on supply guarantee demand constraints (hereinafter referred to as: method), the method comprising the following steps:

[0049] S1: Calculate the proportion α of the important load supplied by the substation to the rated capacity of the substation.

[0050] Specifically, the proportion of the important load supplied by the substation to the rated capacity of the substation is calculated as follows:

[0051]

[0052] Where P imp,load Indicates the important load supplied by the substation, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

[0053] S2: Calculate the substation load rate β after the maximum capacity main transformer N-1 at the time of high load.

[0054] Specifically, the substation load rate β after the maximum capacity main transformer N-1 at the time of high load is calculated as shown in the following formula:

[0055]

[0056] Where P max,load represents the load of the substation at the maximum load moment, max{S1,S2,…,S i} indicates taking the maximum capacity of the substation main transformer.

[0057] S3: Calculate the ratio δ between the output power of power sources connected to the supply area of ​​220 kV substation at a voltage level of 110 kV or below and the important loads supplied by the 220 kV substation.

[0058] Specifically, first of all, the power capacity of the 220 kV substation supply area connected through the 110 kV and below voltage level is counted, and then the output power of this part of the power is calculated, as shown in the following formula:

[0059] P resource =λ t ermal S termal +λ ydro S ydro +λ RES S RES (3)

[0060] Where P resource It indicates the output power of the power supply connected to the supply area of ​​220 kV substation at a voltage level of 110 kV or below, λ thermal Indicates the output coefficient of thermal power unit, S thermal represents the installed capacity of thermal power plant, λ hydro Indicates the output coefficient of the hydropower unit, S hydro represents the installed capacity of the hydropower generator, λ RES Represents the output coefficient of new energy, S RES represents the installed capacity of new energy. thermal , hydro , RES Can be obtained based on historical operating data.

[0061] Then, calculate the ratio δ between the output power of the power supply connected to the 220 kV substation through the voltage level of 110 kV and below and the important load supplied by the 220 kV substation, as shown in the following formula:

[0062]

[0063] S4: Calculate the ratio ε of the sum of the powers flowing out of the substation node to the sum of the powers flowing into the substation node.

[0064] Specifically, first, usually, the 220 kV substation is connected to the surrounding 220 kV substations through transmission lines, and power is exchanged through transmission lines under different operation modes. Taking the analyzed 220 kV substation as the object, the sum of the power flowing into the substation node and the sum of the power flowing out of the substation node are calculated, as shown in the following formula:

[0065]

[0066] N=N1+N2 (7)

[0067] Where P in,sub Represents the sum of the power flowing into the substation node, P j,line,in represents the power flowing into the substation node from the jth transmission line, N1 represents the number of transmission lines through which the power flows into the substation node; P out,sub represents the sum of the power flowing out of the substation node, P k,line,out represents the power flowing out of the substation node on the kth transmission line, N2 represents the number of transmission lines through which the power flows out of the substation node; N represents the number of transmission lines between the 220 kV substation and the surrounding 220 kV substations.

[0068] Then, the ratio ε of the sum of the power flowing out of the substation node to the sum of the power flowing into the substation node is calculated as shown in the following formula:

[0069]

[0070] When the sum of the power flowing out of the substation node is 0, let P out,sub =0.1P in,sub .

[0071] S5: Count the 110 kV load and 10 kV load that cannot be transferred through the 110 kV transmission line under the 220 kV substation, and calculate the ratio η between the non-transferable load and the rated capacity of the substation.

[0072] Specifically, the 110 kV load and 10 kV load that cannot be transferred through the 110 kV transmission line under the 220 kV substation are counted, and the ratio η between the non-transferable load and the rated capacity of the substation is calculated, as shown in the following formula:

[0073]

[0074] Where P untransfer,110 It represents the 110 kV load that cannot be transferred through the 110 kV transmission line, Puntransfer,10 Indicates 10 kV load that cannot be transferred.

[0075] S6: Based on the supply guarantee demand, construct the power balance constraints that all 220 kV substations need to meet.

[0076] Specifically, based on the demand for guaranteed supply, all 220 kV substations need to meet power balance, that is, there must be no load outage, as shown in the following formula:

[0077] P in,sub +P resource =P load +P ESS +P out,sub (10)

[0078] Where P load Indicates the load within the power supply area of ​​220 kV substation; P ESS Indicates the energy storage power in the power supply area of ​​220 kV substation, P ESS ≥0 indicates that the energy storage is in the charging state, P ESS <0 indicates that the energy storage is in a discharging state.

[0079] S7: Establish an objective function F and calculate the objective function value.

[0080] Specifically, an objective function F is established. The objective function F comprehensively considers the proportion of the important load supplied by the substation to the rated capacity of the substation α, the substation load rate β after the maximum capacity main transformer N-1 of the substation at the time of heavy load, the ratio δ between the output power of the power source connected through the voltage level of 110 kV and below in the supply area of ​​220 kV substation and the important load supplied by the 220 kV substation, the ratio ε between the sum of the power flowing out of the substation node and the sum of the power flowing into the substation node, the ratio η between the non-transferable load and the rated capacity of the substation, and the power balance constraint. The objective function F is shown as follows:

[0081]

[0082] Through the above analysis method, different 220 kV substations in the area are analyzed and calculated to obtain the objective function value.

[0083] S8: Sort the objective function values ​​of different 220 kV substations from large to small. The substation with a larger objective function value is more important in the power grid and is a more critical substation.

[0084] Then, according to the size of the objective function values ​​of different 220 kV substations, they are sorted from large to small. The substation with a larger objective function value is more important in the power grid and is a more critical substation.

[0085] Example

[0086] Taking a regional power grid as an example, the wiring diagram of the regional power grid 220 kV and above is as follows Figure 2 As shown, Figure 2 The power flow diagram of the regional power grid under the summer mode in 2024 is given in the table. According to the power flow diagram and the important loads supplied by each 220 kV substation, the output power of 110 kV and below power sources in the supply area, and the non-transferable load conditions, the values ​​of each indicator are calculated and the objective function value is obtained by solving the problem. The results are shown in the following table:

[0087]

[0088]

[0089] From the above example analysis, it can be seen that the order of importance of 220 kV substations in this area under the summer mode of 2024 is consistent with the results after comparison with the actual power grid.

[0090] The beneficial effects of the 220 kV key substation identification method based on supply guarantee demand constraints provided in this embodiment include:

[0091] The proposed method can effectively identify the importance of 220 kV substations in the power grid, which is beneficial to the reinforcement of weak links in power grid planning and to the operators to strengthen the inspection, operation and maintenance of weak links. It has very important significance for engineering practice and power grid planning and operation.

[0092] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0093] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A 220 kV key substation identification method based on supply demand constraints, characterized in that: The method comprises the following steps: S1: Calculate the proportion of the important load supplied by the substation to the rated capacity of the substation α; S2: Calculate the substation load rate β after the maximum capacity main transformer N-1 at the time of high load; S3: Calculate the ratio δ between the output power of the power source connected to the supply area of ​​220 kV substation at a voltage level of 110 kV or below and the important load supplied by the 220 kV substation; S4: Calculate the ratio ε of the sum of the power flowing out of the substation node to the sum of the power flowing into the substation node; S5: Count the 110 kV load and 10 kV load that cannot be transferred through the 110 kV transmission line under the 220 kV substation, and calculate the ratio η between the non-transferable load and the rated capacity of the substation; S6: Based on the supply guarantee demand, construct the power balance constraints that all 220 kV substations need to meet; S7: Establish an objective function F and calculate the objective function value; S8: Sort the objective function values ​​of different 220 kV substations from large to small. The substation with a larger objective function value is more important in the power grid and is a more critical substation.

2. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S1, the proportion of the important load supplied by the substation to the rated capacity of the substation is calculated as follows: Where P imp,load Indicates the important load supplied by the substation, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

3. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S2, the substation load rate β after the maximum capacity main transformer N-1 at the time of high load is calculated as shown in the following formula: Where P max,load represents the load of the substation at the maximum load moment, max{S1,S2,…,S i } represents the maximum capacity of the main transformer of the substation, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

4. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S3, the ratio δ between the output power of the power source connected to the supply area of ​​220 kV substation through the voltage level of 110 kV and below and the important load supplied by the 220 kV substation is calculated as shown in the following formula: Where P resource It indicates the output power of the power supply connected to the supply area of ​​220 kV substation through the voltage level of 110 kV and below, P imp,load Indicates the important loads supplied by the substation.

5. The 220 kV key substation identification method based on supply demand constraints according to claim 4 is characterized in that: In S3, the power supply output power P resource , as shown below: P resource =λ termal S termal +λ ydro S ydro +λ RES S RES In the formula, λ thermal Indicates the output coefficient of thermal power unit, S thermal represents the installed capacity of thermal power plant, λ hydro Indicates the output coefficient of the hydropower unit, S hydro represents the installed capacity of the hydropower generator, λ RES Represents the output coefficient of new energy, S RES Represents the installed capacity of new energy.

6. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S4, the ratio ε of the sum of the power flowing out of the substation node to the sum of the power flowing into the substation node is calculated, as shown in the following formula: When the sum of the power flowing out of the substation node is 0, let P out,sub =0.1P in,sub , where P in,sub Represents the sum of the power flowing into the substation node, P out,sub Represents the sum of the powers flowing out of the substation node.

7. The 220 kV key substation identification method based on supply demand constraints according to claim 6 is characterized in that: In S4, the sum of the power flowing out of the substation node and the sum of the power flowing into the substation node are calculated as shown in the following formula: N=N1+N2 Where P j,line,in represents the power flowing into the substation node from the jth transmission line, N1 represents the number of transmission lines through which the power flows into the substation node; P k,line,out represents the power flowing out of the substation node on the kth transmission line, N2 represents the number of transmission lines through which the power flows out of the substation node; N represents the number of transmission lines between the 220 kV substation and the surrounding 220 kV substations.

8. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S5, the ratio η between the non-transferable load and the rated capacity of the substation is calculated as shown in the following formula: Where P untransfer,110 It represents the 110 kV load that cannot be transferred through the 110 kV transmission line, P untransfer,10 Indicates the 10 kV load that cannot be transferred, S i It represents the rated capacity of the i-th main transformer in the substation, and n represents the number of main transformers in the substation.

9. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S6, the power balance constraint that all 220 kV substations need to meet is constructed as shown in the following formula: P in,sub +P resource =P load +P ESS +P out,sub Where P in,sub Represents the sum of the power flowing into the substation node, P resource It indicates the output power of the power supply connected to the supply area of ​​220 kV substation through the voltage level of 110 kV and below, P load Indicates the load within the power supply area of ​​220 kV substation; P ESS Indicates the energy storage power in the power supply area of ​​220 kV substation, P out,sub Represents the sum of the powers flowing out of the substation node.

10. The 220 kV key substation identification method based on supply demand constraints according to claim 1 is characterized in that: In S7, the objective function F is as follows:

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