Method and system for determining expansion scheme of 220kv substation considering power supply capacity

Abstract

The application discloses a kind of 220 kilovolt substation expansion scheme determination methods considering power supply capacity, including obtaining the data information of target power system;Load rate after maximum capacity main transformer N-1 fault in each 220 kilovolt substation in target power system is calculated;The expansion demand and main transformer capacity demand of each 220 kilovolt substation in target power system are determined;Determine several expansion schemes and calculate corresponding comprehensive evaluation coefficient;According to comprehensive evaluation coefficient, the final 220 kilovolt substation expansion scheme is determined.The application also discloses a kind of systems for implementing the 220 kilovolt substation expansion scheme determination method considering power supply capacity described above.The application not only can realize the determination of 220 kilovolt substation expansion scheme considering power supply capacity, but also has higher reliability, better accuracy, and the scheme is more scientific and reasonable.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electrical automation, and particularly relates to a 220-kilovolt substation expansion scheme determination method and system considering power supply capacity. BACKGROUND

[0002] With the development of economy and technology and the improvement of people's living standards, electric energy has become an essential secondary energy in people's production and life, bringing endless convenience to people's production and life. Therefore, guaranteeing the stable and reliable supply of electric energy has become one of the most important tasks of the power system.

[0003] At present, the 220-kilovolt substation in the power system has a high load rate under normal operation due to the development of power grid load, and the 220-kilovolt substation has great load pressure. Moreover, even if the load transfer of the lower power grid is considered under the N-1 fault condition of the main transformer of the 220-kilovolt substation, the remaining main transformer of the 220-kilovolt substation may still be overloaded. This situation has greatly affected the safe and stable operation of the power system.

[0004] Therefore, it is of great significance to expand the 220-kilovolt substation. However, the current expansion scheme for the 220-kilovolt substation is formulated by power system personnel based on the short-term and long-term planning scheme of the power grid. However, this method does not take into account the actual situation of the 220-kilovolt substation, and therefore its reliability and accuracy are poor. SUMMARY

[0005] One of the purposes of the present application is to provide a 220-kilovolt substation expansion scheme determination method considering power supply capacity, which has high reliability, good accuracy and is scientific and reasonable.

[0006] The second purpose of the present application is to provide a system for implementing the 220-kilovolt substation expansion scheme determination method considering power supply capacity.

[0007] The 220-kilovolt substation expansion scheme determination method considering power supply capacity provided by the present application comprises the following steps:

[0008] S1. Obtain data information of a target power system;

[0009] S2. Calculate the load rate of each 220-kilovolt substation in the target power system after the N-1 fault of the maximum capacity main transformer according to the data information obtained in step S1;

[0010] S3. Determine the expansion demand and main transformer capacity demand of each 220-kilovolt substation in the target power system according to the load rate obtained in step S2;

[0011] S4. Determine several expansion schemes according to the data information determined in step S3 and the parameter information of the 220 kV substation;

[0012] S5. Calculate the comprehensive evaluation coefficient of each expansion scheme according to the expansion scheme obtained in step S4;

[0013] S6. Determine the final 220 kV substation expansion scheme according to the comprehensive evaluation coefficient of each expansion scheme obtained in step S5.

[0014] Step S2: According to the data information obtained in step S1, calculate the load rate of each 220 kV substation in the target power system after the N-1 fault of the maximum capacity main transformer, which specifically includes the following steps:

[0015] The rated capacity S of the remaining transformer of the 220 kV substation after the N-1 fault of the rated maximum capacity main transformer is calculated by the following formula total,N-1 :

[0016]

[0017] In the formula, S i is the rated capacity of the i-th main transformer of the 220 kV substation; n is the number of main transformers of the 220 kV substation; max{S1, S2,..., S n} represents the maximum rated capacity of each main transformer of the 220 kV substation;

[0018] The load rate β of the 220 kV substation after the N-1 fault of the rated maximum capacity main transformer is calculated by the following formula, considering the transfer load of the lower-level power grid:

[0019]

[0020] In the formula, P 0,max is the maximum load of the 220 kV substation under normal operation mode; P trans is the transferable load of the lower-level power grid.

[0021] Step S3: Determine the expansion demand and main transformer capacity demand of each 220 kV substation in the target power system according to the load rate obtained in step S2, which specifically includes the following steps:

[0022] According to the obtained load rate β of the 220 kV substation, the expansion demand and main transformer capacity demand of the 220 kV substation are determined by the following rules:

[0023] If β < 100%, it is determined that the 220 kV substation does not need to be expanded;

[0024] If β≥100%, then the 220 kV substation needs to be expanded, and the main transformer needs to have an increased capacity.

[0025] Step S4, which involves determining several expansion schemes based on the data information obtained in step S3 and the parameter information of the 220 kV substation, specifically includes the following steps:

[0026] The number of main transformers in a 220 kV substation is set to be less than or equal to 3, and the capacity specifications of the main transformers in the 220 kV substation are 120 MVA, 180 MVA and 240 MVA.

[0027] Scenario 1 - A 220 kV substation has one main transformer:

[0028] First expansion plan: Add one main transformer;

[0029] The power supply capacity enhancement value P of the 220 kV substation is calculated using the following formula. 1,supply :

[0030] P 1,supply =min{S expand,capacity ,S1}

[0031] In the formula S expand,capacity S1 represents the capacity of the newly added main transformer; S2 represents the capacity of the existing main transformer in the 220 kV substation.

[0032] Scenario 2 - A 220 kV substation has 2 main transformers:

[0033] (1) When (β-1)S total,N-1 When S1 = S2 and S2 is greater than or equal to 0, the expansion schemes include the second expansion scheme and the third expansion scheme:

[0034] Second expansion plan: Add one main transformer;

[0035] The power supply capacity enhancement value P of the 220 kV substation is calculated using the following formula. 2,supply :

[0036] P 2,supply =min{S expand,capacity ,S1,S2}

[0037] In the formula S expand,capacity S1 represents the capacity of the newly added main transformer; S2 represents the capacity of the existing first main transformer in the 220 kV substation; S3 represents the capacity of the existing second main transformer in the 220 kV substation.

[0038] The third expansion plan is to replace the existing two main transformers with larger capacity main transformers.

[0039] The power supply capacity promotion value P of the 220 kV substation is calculated by the following formula 3,supply :

[0040] P 3,supply =S replaced -min{S1,S2}

[0041] In the formula, S replaced is the capacity of the main transformer of the 220 kV substation after replacement;

[0042] (2) When (β-1)S total,N-1 ≤ 6 and S1≠S2, the expansion scheme includes a fourth expansion scheme and a fifth expansion scheme:

[0043] The fourth expansion scheme: among the existing two main transformers, the main transformer with smaller capacity is replaced by a main transformer with larger capacity;

[0044] The power supply capacity promotion value P of the 220 kV substation is calculated by the following formula 4,supply :

[0045] P 4,supply =min{S 1-replaced ,S 2-replaced}-min{S1,S2}

[0046] In the formula, S 1-replaced and S 2-replaced are the capacities of the two main transformers of the 220 kV substation after replacement;

[0047] The fifth expansion scheme: one main transformer is added;

[0048] The power supply capacity promotion value P of the 220 kV substation is calculated by the following formula 5,supply :

[0049] P 5,supply =min{max{S1,S2},S expand,capacity}

[0050] In the formula, max{S1,S2} represents the capacity value of the main transformer with larger capacity among the existing two main transformers;

[0051] (3) When (β-1)S total,N-1 > 6 and S1≠S2, the expansion scheme includes a sixth expansion scheme and a seventh expansion scheme:

[0052] The sixth expansion scheme: one main transformer is added;

[0053] The power supply capacity promotion value P of the 220 kV substation is calculated by the following formula 6,supply : ​​​​

[0054] P 6,supply =min{max{S1,S2},S expand,capacity}

[0055] In the formula, max{S1,S2} represents the capacity value of the larger of the two existing main transformers.

[0056] The seventh expansion plan is to replace the existing two main transformers with larger capacity main transformers.

[0057] The power supply capacity enhancement value P of the 220 kV substation is calculated using the following formula. 7,supply :

[0058] P 7,supply =min{S 1-replaced ,S 2-replaced}-min{S1,S2}

[0059] In the formula S 1-replaced and S 2-replaced This refers to the capacity of the two main transformers in the replaced 220 kV substation.

[0060] Scenario 3 - A 220 kV substation has 3 main transformers:

[0061] (1) When (β-1)S total,N-1 When the capacity of all three main transformers is equal to or greater than zero, the capacity expansion schemes include the eighth and ninth expansion schemes:

[0062] Eighth expansion plan: Add one main transformer;

[0063] The calculated power supply capacity enhancement value P of the 220 kV substation was obtained. 8,supply For P 8,supply =S expand,capacity ;

[0064] Ninth expansion plan: Replace the existing three main transformers with larger capacity main transformers;

[0065] The power supply capacity enhancement value P of the 220 kV substation is calculated using the following formula. 9,supply :

[0066] P 9,supply =S replaced -S now

[0067] In the formula S replaced The sum of the capacities of the two main transformers in the 220 kV substation after the main transformer replacement; S now The capacity of the two main transformers in the 220 kV substation before the replacement of the main transformer;

[0068] (2) When (β-1)S total,N-1 ≤ 6 and the capacities of the three main transformers are not completely equal, the expansion schemes include a tenth expansion scheme and an eleventh expansion scheme:

[0069] The tenth expansion scheme: among the three main transformers, the main transformer with the smallest capacity is replaced by a main transformer with a larger capacity;

[0070] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula: 10,supply :

[0071] P 10,supply = (S replaced -max{S 1-replace ,S 2-replace ,S 3-replace})-(S now -max{S1,S2,S3})

[0072] In the formula, S 1-replace ,S 2-replace ,S 3-replace are the capacities of the three main transformers of the 220 kV substation after the main transformer is replaced, and S now is the capacity sum of the three main transformers of the 220 kV substation before the main transformer is replaced.

[0073] The eleventh expansion scheme: one main transformer is added;

[0074] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula: 11,supply :

[0075] P 11,supply = min{max{S1,S2,S3},S expand,capacity}

[0076] In the formula, max{S1,S2,S3} represents the capacity value of the main transformer with the largest capacity among the three main transformers;

[0077] (3) When (β-1)S total,N-1 > 6 and the capacities of the three main transformers are not completely equal, the expansion schemes include a twelfth expansion scheme and a thirteenth expansion scheme:

[0078] The twelfth expansion scheme: among the three main transformers, the two main transformers with smaller capacities are replaced by main transformers with larger capacities;

[0079] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula: 12,supply :

[0080] P12,supply = (S replaced - max{S 1-replace , S 2-replace , S 3-replace}) - (S now - max{S1, S2, S3})

[0081] wherein S 1-replace , S 2-replace , and S 3-replace are the capacities of the three main transformers of the 220 kV substation after the main transformers are replaced, respectively; S now is the sum of the capacities of the three main transformers of the 220 kV substation before the main transformers are replaced; and S 13,supply is the sum of the capacities of the three main transformers of the 220 kV substation after the main transformers are replaced.

[0082] The thirteenth capacity expansion scheme is to add one main transformer.

[0083] The power supply capacity improvement value P 13,supply of the 220 kV substation is calculated by using the following formula:

[0084] P expand,capacity = min{max{S1, S2, S3}, S k,i,j}

[0085] wherein max{S1, S2, S3} represents the capacity value of the main transformer with the largest capacity among the three main transformers.

[0086] The comprehensive evaluation coefficient of each capacity expansion scheme is calculated according to the capacity expansion scheme obtained in step S4, and the calculation includes the following steps:

[0087] The comprehensive evaluation coefficient δ of each capacity expansion scheme is calculated by using the following formula:

[0088]

[0089] wherein M i,j is the investment value of the i-th main transformer of the 220 kV substation under the k-th capacity demand scheme and expanded to the j-th capacity main transformer; x i,j is a binary variable indicating whether the i-th main transformer of the 220 kV substation adopts the j-th capacity main transformer, and x i,j = 1 indicates that the i-th main transformer of the 220 kV substation adopts the j-th capacity main transformer, and x k,supply = 0 indicates that the i-th main transformer of the 220 kV substation does not adopt the j-th capacity main transformer; P k is the power supply capacity improvement value corresponding to the k-th capacity expansion scheme; and M' is the other investment cost brought by the expansion of the main transformer capacity.In order to ensure the power supply safety margin of the maximum main transformer capacity of the 220 kV substation after the N-1 fault of the transformer, and S' i In order to expand the capacity of the i-th main transformer in the 220 kV substation according to the k-th expansion scheme, N is the number of main transformers in the 220 kV substation after expansion according to the k-th expansion scheme.

[0090] The comprehensive evaluation coefficient of each expansion scheme obtained in step S5 is determined in step S6, and the final 220 kV substation expansion scheme is determined, which specifically includes the following steps:

[0091] According to the comprehensive evaluation coefficient of each expansion scheme obtained in step S5, the expansion scheme corresponding to the minimum comprehensive evaluation coefficient δ is selected as the final 220 kV substation expansion scheme.

[0092] The application also provides a system for realizing the method for determining the 220 kV substation expansion scheme considering the power supply capacity, which comprises a data acquisition module, a load rate calculation module, a demand determination module, a scheme construction module, an evaluation module and a scheme determination module. The data acquisition module, the load rate calculation module, the demand determination module, the scheme construction module, the evaluation module and the scheme determination module are sequentially connected. The data acquisition module is used to acquire data information of a target power system and upload the data information to the load rate calculation module. The load rate calculation module is used to calculate the load rate of each 220 kV substation in the target power system after the N-1 fault of the maximum capacity main transformer according to the received data information and the acquired data information, and upload the data information to the demand determination module. The demand determination module is used to determine the expansion demand and the main transformer capacity demand of each 220 kV substation in the target power system according to the received data information and the obtained load rate, and upload the data information to the scheme construction module. The scheme construction module is used to determine a plurality of expansion schemes according to the received data information, the determined data information and the parameter information of the 220 kV substation, and upload the data information to the evaluation module. The evaluation module is used to calculate the comprehensive evaluation coefficient of each expansion scheme according to the received data information and the obtained expansion scheme, and upload the data information to the scheme determination module. The scheme determination module is used to determine the final 220 kV substation expansion scheme according to the received data information and the obtained comprehensive evaluation coefficient of each expansion scheme.

[0093] The present invention provides a method and system for determining the capacity expansion scheme of a 220 kV substation that takes into account power supply capacity. Based on the load rate, the power supply capacity of the 220 kV substation is evaluated, and a corresponding capacity expansion scheme is constructed according to the evaluation results and the existing parameter information of the 220 kV substation. The capacity expansion scheme is then evaluated. Therefore, the present invention can not only determine the capacity expansion scheme of a 220 kV substation that takes into account power supply capacity, but also has higher reliability, better accuracy, and a more scientific and reasonable scheme. Attached Figure Description

[0094] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0095] Figure 2 This is a schematic diagram of the functional modules of the system of the present invention. Detailed Implementation

[0096] like Figure 1 The diagram shown is a flowchart of the method of the present invention: The method for determining the capacity expansion scheme of a 220 kV substation considering power supply capacity disclosed in this invention includes the following steps:

[0097] S1. Obtain data information from the target power system;

[0098] S2. Based on the data obtained in step S1, calculate the load rate of each 220 kV substation in the target power system after a fault in the maximum capacity main transformer N-1; specifically including the following steps:

[0099] The rated capacity S of the remaining transformers in a 220 kV substation after a fault occurs in the main transformer N-1 with the maximum rated capacity, is calculated using the following formula. total,N-1 :

[0100]

[0101] In the formula S i Let Si be the rated capacity of the i-th main transformer in the 220 kV substation; n be the number of main transformers in the 220 kV substation; max{S1,S2,...,Si} n} represents the maximum rated capacity of each main transformer in a 220 kV substation;

[0102] The load factor β of a 220 kV substation, considering the load transferred from the downstream power grid, is calculated using the following formula after a fault in the main transformer with rated maximum capacity N-1.

[0103]

[0104] In the formula P 0,max P represents the maximum load under normal operating conditions of a 220 kV substation. transThe load of the lower-level power grid is converted to the load of the upper-level power grid;

[0105] S3. Determine the expansion demand and main transformer capacity demand of each 220 kV substation in the target power system according to the load rate obtained in step S2; specifically including the following steps:

[0106] According to the obtained load rate β of the 220 kV substation, the expansion demand and main transformer capacity demand of the 220 kV substation are determined by the following rules:

[0107] If β < 100%, it is determined that the 220 kV substation does not need to be expanded;

[0108] If β ≥ 100%, it is determined that the 220 kV substation needs to be expanded, and the main transformer has the demand for expansion capacity;

[0109] S4. Determine a plurality of expansion schemes according to the data information determined in step S3 and the parameter information of the 220 kV substation; specifically including the following steps:

[0110] The currently commonly used main transformer capacity of the 220 kV substation is 120 MVA, 180 MVA and 240 MVA; according to the actual situation of the power grid, the number of main transformers of most existing 220 kV substations is less than or equal to 3;

[0111] Therefore, it is set that the number of main transformers of the 220 kV substation is less than or equal to 3, and the main transformer capacity specifications of the 220 kV substation are 120 MVA, 180 MVA and 240 MVA;

[0112] Scenario one - the 220 kV substation has 1 main transformer:

[0113] First expansion scheme: add 1 main transformer;

[0114] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 1,supply :

[0115] P 1,supply =min{S expand,capacity ,S1}

[0116] In the formula, S expand,capacity is the capacity of the newly added 1 main transformer, which can be 12, 18 or 24; S1 is the capacity of the main transformer already existing in the 220 kV substation;

[0117] Scenario two - the 220 kV substation has 2 main transformers:

[0118] (1) When (β-1)S total,N-1 ≥ 0 and S1 = S2, the expansion schemes include the second expansion scheme and the third expansion scheme:

[0119] The second capacity expansion scheme: adding one main transformer;

[0120] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 2,supply :

[0121] P 2,supply = min{S expand,capacity ,S1,S2}

[0122] In the formula, S expand,capacity is the capacity of the added main transformer, which can be 12, 18 or 24; S1 is the capacity of the first main transformer currently existing in the 220 kV substation; and S2 is the capacity of the second main transformer currently existing in the 220 kV substation.

[0123] The third capacity expansion scheme: replacing the existing two main transformers with main transformers with larger capacity;

[0124] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 3,supply :

[0125] P 3,supply = S replaced -min{S1,S2}

[0126] In the formula, S replaced is the capacity of the main transformer of the 220 kV substation after replacement; and the value of the power supply capacity improvement value P 3,supply may be 6 or 12.

[0127] (2) When (β-1)S total,N-1 ≤ 6 and S1≠S2, the capacity expansion schemes include a fourth capacity expansion scheme and a fifth capacity expansion scheme:

[0128] The fourth capacity expansion scheme: replacing the main transformer with smaller capacity among the existing two main transformers with a main transformer with larger capacity;

[0129] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 4,supply :

[0130] P 4,supply = min{S 1-replaced ,S 2-replaced}-min{S1,S2}

[0131] In the formula, S 1-replaced and S 2-replaced are the capacities of the two main transformers of the 220 kV substation after replacement; and the value of the power supply capacity improvement value P 4,supply may be 6 or 12.

[0132] The fifth capacity expansion scheme is to add one main transformer;

[0133] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 5,supply :

[0134] P 5,supply = min{max{S1, S2}, S expand,capacity}

[0135] max{S1, S2} represents the capacity value of the main transformer with larger capacity in the existing two main transformers;

[0136] (3) When (β-1)S total,N-1 > 6 and S1≠ S2, the capacity expansion scheme includes the sixth capacity expansion scheme and the seventh capacity expansion scheme:

[0137] The sixth capacity expansion scheme is to add one main transformer;

[0138] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 6,supply :

[0139] P 6,supply = min{max{S1, S2}, S expand,capacity}

[0140] max{S1, S2} represents the capacity value of the main transformer with larger capacity in the existing two main transformers;

[0141] The seventh capacity expansion scheme is to replace the existing two main transformers with main transformers with larger capacity;

[0142] The power supply capacity improvement value P of the 220 kV substation is calculated by the following formula 7,supply :

[0143] P 7,supply = min{S 1-replaced , S 2-replaced} - min{S1, S2}

[0144] S 1-replaced and S 2-replaced are the capacities of the two main transformers of the 220 kV substation after replacement; at this time, the value of the power supply capacity improvement value P 7,supply may be 6 or 12;

[0145] Scenario three - the 220 kV substation has three main transformers:

[0146] (1) When (β-1)S total,N-1When ≥0 and the capacities of the three main transformers are all equal, the expansion schemes include an eighth expansion scheme and a ninth expansion scheme:

[0147] The eighth expansion scheme: one main transformer is newly added;

[0148] The power supply capacity improvement value P of the 220 kV substation is calculated as follows: 8,supply P = S - S 8,supply ; expand,capacity ;

[0149] The ninth expansion scheme: the existing three main transformers are replaced by main transformers with larger capacities;

[0150] The power supply capacity improvement value P of the 220 kV substation is calculated as follows: 9,supply :

[0151] P 9,supply = S replaced - S now

[0152] In the formula, S replaced is the sum of the capacities of the two main transformers of the 220 kV substation after the main transformers are replaced; S now is the sum of the capacities of the two main transformers of the 220 kV substation before the main transformers are replaced; at this time, the value of the power supply capacity improvement value P 9,supply may be 12 or 24;

[0153] (2) When (β-1)S total,N-1 ≤6 and the capacities of the three main transformers are not all equal, the expansion schemes include a tenth expansion scheme and an eleventh expansion scheme:

[0154] The tenth expansion scheme: among the three main transformers, the main transformer with the smallest capacity is replaced by a main transformer with a larger capacity;

[0155] The power supply capacity improvement value P of the 220 kV substation is calculated as follows: 10,supply :

[0156] P 10,supply = (S replaced - max{S 1-replace , S 2-replace , S 3-replace}) - (S now - max{S1, S2, S3})

[0157] In the formula, S 1-replace , S 2-replace , S 3-replace are the sums of the capacities of the three main transformers of the 220 kV substation after the main transformers are replaced; S nowthe sum of the capacities of the three main transformers of the 220 kV substation before the main transformers are replaced; at this time, the value of the power supply capacity improvement value P 10,supply may be 6 or 12;

[0158] Eleventh capacity expansion scheme: one main transformer is newly added;

[0159] The power supply capacity improvement value P of the 220 kV substation is calculated by using the following formula 11,supply :

[0160] P 11,supply = min{max{S1,S2,S3},S expand,capacity}

[0161] In the formula, max{S1,S2,S3} represents the capacity value of the main transformer with the largest capacity among the existing three main transformers;

[0162] (3) When (β-1)S total,N-1 > 6 and the capacities of the three main transformers are not completely equal, the capacity expansion schemes include a twelfth capacity expansion scheme and a thirteenth capacity expansion scheme:

[0163] Twelfth capacity expansion scheme: among the three main transformers, two main transformers with smaller capacities are replaced by main transformers with larger capacities;

[0164] The power supply capacity improvement value P of the 220 kV substation is calculated by using the following formula 12,supply :

[0165] P 12,supply = (S replaced -max{S 1-replace ,S 2-replace ,S 3-replace})-(S now -max{S1,S2,S3})

[0166] In the formula, S 1-replace ,S 2-replace ,S 3-replace are the sum of the capacities of the three main transformers of the 220 kV substation after the main transformers are replaced; S now is the sum of the capacities of the three main transformers of the 220 kV substation before the main transformers are replaced; at this time, the value of the power supply capacity improvement value P 12,supply may be 12, 18 or 24;

[0167] Thirteenth capacity expansion scheme: one main transformer is newly added;

[0168] The power supply capacity improvement value P of the 220 kV substation is calculated by using the following formula 13,supply :

[0169] P13,supply = min{max{S1, S2, S3}, S expand,capacity}

[0170] max{S1, S2, S3} represents the capacity value of the main transformer with the largest capacity among the existing three main transformers;

[0171] S5. Calculate the comprehensive evaluation coefficient of each expansion scheme according to the expansion scheme obtained in step S4; specifically including the following steps:

[0172] In actual engineering, when expanding the capacity of a 220 kV substation, its economic benefits and future adaptability also need to be considered, therefore, the following formula is used to calculate the comprehensive evaluation coefficient δ of each expansion scheme:

[0173]

[0174] max{S1, S2, S3} represents the capacity value of the main transformer with the largest capacity among the existing three main transformers; k,i,j the investment value of the i-th main transformer of the 220 kV substation under the k-th capacity demand scheme, where j is 1, 2 or 3, corresponding to 120 MVA capacity, 180 MVA capacity and 240 MVA capacity respectively; x i,j is a binary variable of whether the i-th main transformer of the 220 kV substation adopts the j-th capacity main transformer, and x i,j = 1 indicates that the i-th main transformer of the 220 kV substation adopts the j-th capacity main transformer, x i,j = 0 indicates that the i-th main transformer of the 220 kV substation does not adopt the j-th capacity main transformer; P k,supply is the power supply capacity improvement value corresponding to the k-th expansion scheme, and k is 1-13; M' is the other investment cost brought by expanding the capacity of the main transformer; ε k is the power supply safety margin after the N-1 fault of the maximum main transformer capacity after expanding the 220 kV substation according to the k-th expansion scheme, and S' i is the capacity of the i-th main transformer of the 220 kV substation after expanding according to the k-th expansion scheme, and N is the number of main transformers of the 220 kV substation after expanding according to the k-th expansion scheme;

[0175] For actual engineering, while ensuring the investment of improving every 10 kVA power supply capacity, the substation needs better future adaptability after expansion, which is reflected in the power supply margin ε k after the N-1 fault of the maximum main transformer capacity after expanding the 220 kV substation;

[0176] S6. Determine the final 220 kV substation expansion scheme according to the comprehensive evaluation coefficient of each expansion scheme obtained in step S5; specifically comprising the following steps:

[0177] According to the comprehensive evaluation coefficient of each expansion scheme obtained in step S5, select the expansion scheme corresponding to the minimum comprehensive evaluation coefficient δ as the final 220 kV substation expansion scheme.

[0178] The method of the application is further described below in combination with an embodiment:

[0179] The effectiveness and adaptability of the method are analyzed by taking an actual 220 kV substation in a province as an example.

[0180] Substation A has 2×18 MW main transformers with a total capacity of 2×180 MVA. The maximum load in 2023 is 301.9 MW, and the load rate α=83.86%. After N-1 of the main transformer, the remaining capacity S of the substation main transformer total,N-1 = 180 MVA.

[0181] After N-1 failure of the largest capacity main transformer in the 220 kV substation, considering the load transfer of the lower grid, the load rate β of the substation is 117.15% ≥ 100%. Therefore, the main transformer capacity demand scenario analysis of the substation is scenario 2, and in this scenario:

[0182] (β-1)S total,N-1 = 3.09 ≥ 0

[0183] S1=S2=180 MVA

[0184] S sub,require = 180 MVA

[0185] When scheme one "adding one transformer" is adopted, the power supply capacity of the 220 kV substation is improved to: P supply = min{S expand,capacity , S1, S2} = 180 MW;

[0186] When scheme two "replacing two larger capacity transformers" is adopted, the power supply capacity of the 220 kV substation is improved to: P supply = 60 MW;

[0187] From the above analysis, it can be seen that:

[0188] When scheme one is adopted, the expansion main transformer capacity is 180 MVA.

[0189]

[0190] In combination with the actual project, the investment of expanding one 180 MVA main transformer is about M1,i,2 = 220 million yuan, and the investment of expanding one 240 MVA main transformer is about M 1i3 = 3300 million yuan. Therefore, the comprehensive evaluation index of benefit and future adaptability is:

[0191]

[0192] When scheme two is adopted, two larger capacity transformers are replaced, and the transformer capacity is 240 MVA. Then there are

[0193]

[0194] Combined with the actual construction of the 220 kV substation, when the substation adopts scheme one, it does not have good construction conditions, that is, the cost of expanding the main transformer capacity of the substation is much larger than M2', and after calculating the comprehensive evaluation index, δ2 < δ1 is obtained. Therefore, scheme two is selected as the main transformer capacity expansion scheme of the substation A.

[0195] Substation B has three 220 kV main transformers, with a total capacity of 2 x 12 + 1 x 18 MVA. The maximum load in 2023 is 34.99 MW, and the load rate α = 83.31%. After the main transformer N-1, the remaining capacity S total,N-1 of the main transformer of the substation is 24 MVA.

[0196] After the N-1 failure of the largest capacity main transformer in the 220 kV substation, considering the load transfer of the lower grid, the load rate β of the substation is 109.25% ≥ 100%. Therefore, the main transformer capacity demand scenario analysis of the substation is scenario 3, and in this scenario:

[0197] 0 < (β-1)S total,N-1 = 2.22 < 6

[0198] S sub,require = 6 MVA

[0199] When scheme one is adopted to replace the existing small capacity main transformer with one 240 MVA main transformer, the power supply capacity of the substation is improved P supply = 6 MW; then

[0200]

[0201] When scheme two is adopted to add one 180 MVA main transformer, the power supply capacity of the expanded 220 kV substation is improved P supply = min{max{S1, S2, S3}, S expand,capacity} = 18 MW; then

[0202]

[0203] Combined with the actual construction of the 220 kV substation, the substation does not have good construction conditions when the substation adopts scheme ②, that is, the capacity of the main transformer of the substation is expanded, and other cost investments are large M1'CM2', and after the comprehensive evaluation index is calculated, δ2>δ1 is obtained, so scheme one is selected as the capacity expansion scheme of the main transformer of the substation A.

[0204] The scheme can consider the capacity demand calculation under different scenarios while improving the power supply capacity of the 220 kV substation, and evaluate the capacity demand calculation method under different scenarios. Combined with the actual engineering and the construction of the 220 kV substation, the capacity expansion cost of the substation is considered, the benefit and future adaptability comprehensive evaluation index is proposed, and then the capacity expansion scheme suitable for the 220 kV substation is selected. The method provides a reasonable analysis basis for power grid planning and operation personnel, and combines the engineering practice, has very important significance, is helpful to improve the safe and stable operation level of the power grid and improve the power supply capacity of the regional 220 kV substation.

[0205] As shown in Figure 2 The system for implementing the method for determining the capacity expansion scheme of the 220 kV substation considering the power supply capacity comprises a data acquisition module, a load rate calculation module, a demand determination module, a scheme construction module, an evaluation module and a scheme determination module. The data acquisition module, the load rate calculation module, the demand determination module, the scheme construction module, the evaluation module and the scheme determination module are sequentially connected. The data acquisition module is used to acquire data information of a target power system and upload the data information to the load rate calculation module. The load rate calculation module is used to calculate the load rate of each 220 kV substation in the target power system after the N-1 fault of the maximum capacity main transformer according to the received data information and the acquired data information, and upload the data information to the demand determination module. The demand determination module is used to determine the capacity expansion demand and the main transformer capacity demand of each 220 kV substation in the target power system according to the received data information and the obtained load rate, and upload the data information to the scheme construction module. The scheme construction module is used to determine a plurality of capacity expansion schemes according to the received data information, the determined data information and the parameter information of the 220 kV substation, and upload the data information to the evaluation module. The evaluation module is used to calculate the comprehensive evaluation coefficient of each capacity expansion scheme according to the received data information and the obtained capacity expansion scheme, and upload the data information to the scheme determination module. The scheme determination module is used to determine the final capacity expansion scheme of the 220 kV substation according to the received data information and the comprehensive evaluation coefficient of each capacity expansion scheme.

Claims

1. A method for determining a 220 kV substation expansion scheme considering power supply capacity, comprising the following steps: S1. Obtain data information from the target power system; S2. Based on the data obtained in step S1, calculate the load rate of each 220 kV substation in the target power system after a fault in the maximum capacity main transformer N-1; specifically including the following steps: The rated capacity S of the remaining transformers in a 220 kV substation after a fault occurs in the main transformer N-1 with the maximum rated capacity, is calculated using the following formula. total,N-1 : In the formula S i Let Si be the rated capacity of the i-th main transformer in the 220 kV substation; n is the number of main transformers in the 220 kV substation; max{S1,S2,...,Si} n } represents the maximum rated capacity of each main transformer in a 220 kV substation; The load factor β of a 220 kV substation, considering the load transferred from the downstream power grid, is calculated using the following formula after a fault in the main transformer with rated maximum capacity N-1. In the formula P 0,max P represents the maximum load under normal operating conditions of a 220 kV substation. trans For loads that can be transferred to the lower-level power grid; S3. Based on the load rate obtained in step S2, determine the expansion requirements and main transformer capacity requirements of each 220 kV substation in the target power system; S4. Based on the data information determined in step S3 and the parameter information of the 220 kV substation, determine several expansion schemes; S5. Based on the expansion schemes obtained in step S4, calculate the comprehensive evaluation coefficient of each expansion scheme; specifically including the following steps: The comprehensive evaluation coefficient δ for each capacity expansion scheme is calculated using the following formula: In the formula M k,i,j The investment value for expanding the i-th main transformer of a 220 kV substation to a j-th capacity main transformer under the k-th capacity demand scheme; x i,j Let x be a binary variable indicating whether the i-th main transformer in a 220 kV substation should be of the j-th capacity. i,j =1 indicates that the i-th main transformer in the 220 kV substation uses the j-th type of main transformer, x i,j =0 indicates that the i-th main transformer in the 220 kV substation does not use the j-th capacity main transformer; P k,supply This represents the power supply capacity improvement value corresponding to the kth expansion scheme; M' represents other investment costs incurred from expanding the capacity of the main transformer; ε k To determine the power supply safety margin after a fault in transformer N-1, the largest main transformer capacity of the 220 kV substation expanded according to expansion scheme k, and... S' i Let N be the capacity of the i-th main transformer in the 220 kV substation after expansion according to the k-th expansion scheme, and let N be the number of main transformers in the 220 kV substation after expansion according to the k-th expansion scheme. S6. Based on the comprehensive evaluation coefficients of each expansion scheme obtained in step S5, determine the final expansion scheme for the 220 kV substation.

2. The method for determining the capacity expansion scheme of a 220 kV substation considering power supply capacity according to claim 1, characterized in that... Step S3, which involves determining the expansion requirements and main transformer capacity requirements of each 220 kV substation in the target power system based on the load rate obtained in step S2, specifically includes the following steps: Based on the obtained load factor β of the 220 kV substation, the expansion requirements and main transformer capacity requirements of the 220 kV substation are determined using the following rules: If β < 100%, then the 220 kV substation does not need to be expanded. If β≥100%, then the 220 kV substation needs to be expanded, and the main transformer needs to have an increased capacity.

3. The method for determining the capacity expansion scheme of a 220 kV substation considering power supply capacity according to claim 2, characterized in that... Step S4, which involves determining several expansion schemes based on the data information obtained in step S3 and the parameter information of the 220 kV substation, specifically includes the following steps: The number of main transformers in a 220 kV substation is set to be less than or equal to 3, and the capacity specifications of the main transformers in the 220 kV substation are 120 MVA, 180 MVA and 240 MVA. Scenario 1 - A 220 kV substation has one main transformer: First expansion plan: Add one main transformer; Scenario 2 - A 220 kV substation has 2 main transformers: (1) When (β-1)S total,N-1 When S1 = S2 and S2 is greater than or equal to 0, the expansion schemes include the second expansion scheme and the third expansion scheme: Second expansion plan: Add one main transformer; The third expansion plan is to replace the existing two main transformers with larger capacity main transformers. (2) When (β-1)S total,N-1 When ≤6 and S1≠S2, the expansion schemes include the fourth expansion scheme and the fifth expansion scheme: Fourth expansion plan: Replace the smaller main transformer with a larger one from the existing two main transformers; Fifth expansion plan: Add one main transformer; (3) When (β-1)S total,N-1 When S1 > 6 and S2 ≠ S2, the expansion schemes include the sixth expansion scheme and the seventh expansion scheme: Sixth expansion plan: Add one main transformer; The seventh expansion plan is to replace the existing two main transformers with larger capacity main transformers. Scenario 3 - A 220 kV substation has 3 main transformers: (1) When (β-1)S total,N-1 When the capacity of all three main transformers is equal to or greater than zero, the capacity expansion schemes include the eighth and ninth expansion schemes: Eighth expansion plan: Add one main transformer; Ninth expansion plan: Replace the existing three main transformers with larger capacity main transformers; (2) When (β-1)S total,N-1 When the capacity of the three main transformers is not exactly equal and the capacity is ≤6, the expansion schemes include the tenth expansion scheme and the eleventh expansion scheme: The tenth expansion plan: Replace the main transformer with the one with the smallest capacity among the three main transformers with a main transformer with a larger capacity. Eleventh expansion plan: Add one main transformer; (3) When (β-1)S total,N-1 When the capacity of the three main transformers is not exactly equal (>6), the expansion schemes include the twelfth and thirteenth expansion schemes: The twelfth expansion plan involves replacing the two smaller main transformers out of the three main transformers with larger ones. Thirteenth expansion plan: Add one main transformer.

4. The method for determining the expansion scheme of a 220 kV substation considering power supply capacity according to claim 3, characterized in that... Step S6, which involves determining the final 220 kV substation expansion plan based on the comprehensive evaluation coefficients of the various expansion schemes obtained in step S5, specifically includes the following steps: Based on the comprehensive evaluation coefficients of each expansion scheme obtained in step S5, the expansion scheme corresponding to the smallest comprehensive evaluation coefficient δ is selected as the final expansion scheme for the 220 kV substation.

5. A system for implementing the method for determining a 220 kV substation expansion scheme considering power supply capacity as described in any one of claims 1 to 4, characterized in that... It includes a data acquisition module, a load rate calculation module, a demand determination module, a solution construction module, an evaluation module, and a solution determination module; the data acquisition module, load rate calculation module, demand determination module, solution construction module, evaluation module, and solution determination module are connected in series; the data acquisition module is used to acquire data information of the target power system and upload the data information to the load rate calculation module; The load factor calculation module calculates the load factor of each 220 kV substation in the target power system after a fault of the maximum capacity main transformer N-1, based on the received and acquired data, and uploads the data to the demand determination module. The demand determination module determines the expansion needs and main transformer capacity needs of each 220 kV substation in the target power system based on the received data and the obtained load factor, and uploads the data to the scheme construction module. The scheme construction module determines several expansion schemes based on the received data, the determined data, and the parameter information of the 220 kV substations, and uploads the data to the evaluation module. The evaluation module is used to calculate the comprehensive evaluation coefficient of each expansion scheme based on the received data and the obtained expansion scheme, and upload the data to the scheme determination module. The scheme determination module is used to determine the final 220 kV substation expansion scheme based on the received data and the comprehensive evaluation coefficient of each expansion scheme.

Images