220 kilovolt transformer substation energy storage capacity optimal configuration method considering electric power and electric quantity balance

Abstract

The invention discloses a 220KV transformer substation energy storage capacity optimal configuration method considering electric power and electric quantity balance. The method comprises the following steps: step 1, calculating the maximum load rate of a 220KV transformer substation in a typical load day; 2, calculating the rated capacity of the residual transformer after the main transformer of the transformer substation has the N-1 fault; 3, calculating the load rate of the main transformer of the substation after the N-1 fault occurs; step 4, calculating the transfer load of the 110 kilovolt transformer substation after the main transformer of the transformer substation has the N-1 fault; step 5, configuring energy storage capacity; and step 6, constructing an objective function. According to the 220 kilovolt transformer substation energy storage capacity optimal configuration method considering electric power and electric quantity balance provided by the invention, under the two scenes of network access and network release of the transformer substation, through energy storage configuration, when the main transformer N-1 with the maximum capacity in the transformer substation breaks down, it can be ensured that the remaining transformers are not overloaded. And meanwhile, the scene of a single main transformer of a transformer substation is considered, and when the main transformer is N-1, the online and offline requirements are still met.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power systems, and in particular to a method for optimizing the configuration of energy storage capacity of a 220 kV substation taking into account electric power balance. Background Art

[0002] In terms of power grid transmission and distribution and ancillary services, the main functions of energy storage technology are power grid peak regulation, loading, starting and relieving transmission congestion, and delaying the upgrade of transmission and distribution networks; in terms of renewable energy grid connection, energy storage is mainly used to smooth renewable energy output, absorb excess power to reduce "wind and solar abandonment", and instant grid connection; in terms of distributed and microgrids, energy storage is mainly used to stabilize system output, serve as a backup power source and improve scheduling flexibility; on the user side, energy storage is mainly used for industrial and commercial peak shaving, demand-side response, and energy cost management. Therefore, actively promoting the application of energy storage technology in the power grid plays an important role in achieving stable operation of electricity at the supply, transmission and user ends.

[0003] At present, the optimization configuration method of energy storage capacity of 220 kV substation may be insufficient due to the lack of accurate and comprehensive data. For example, traditional methods fail to fully consider factors such as the load characteristics of the substation, the performance indicators of the energy storage equipment, and the operation status of the power grid, which will affect the accuracy and effectiveness of the optimization configuration; on the other hand, some traditional optimization methods only consider the energy optimization configuration under static conditions, and do not consider the dynamic changes in the operation status of the power grid. In actual operation, factors such as power grid load and renewable energy output will change at any time, and the energy storage capacity configuration needs to be adjusted dynamically, and some traditional methods may not be able to achieve timely dynamic optimization. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a 220 kV substation energy storage capacity optimization configuration method taking into account power balance, which can meet both the power balance requirement and the safe and reliable power supply requirement of the power grid when a main transformer N-1 failure occurs.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance, comprising the following steps: Step 1, calculate the maximum load rate of the 220 kV substation on a typical load day; Step 2, calculate the rated capacity of the remaining transformers after N-1 faults occur in the main transformer of the substation; Step 3, calculating the load rate after N-1 faults occur in the main transformer of the substation; Step 4, calculate the load transferred by the 110 kV substation after the N-1 fault occurs in the main transformer of the substation; Step 5: Configure energy storage capacity; Step 6: Construct the objective function.

[0006] Preferably, the calculation formula of step 1 is as follows: (1); In the formula, Indicates the maximum load rate under normal operation of the substation. It indicates the maximum load of a typical load day under normal operation of a 220 kV substation. represents the rated capacity of the i-th transformer in the substation, Indicates the number of transformers in the substation.

[0007] Preferably, the step 2 is specifically as follows: When the number of main transformers in the substation is greater than 1, the rated capacity of the remaining transformers after N-1 failures of the substation main transformers As shown below: (2); In the formula, represents the sum of the rated capacities of the remaining transformers after the failure of the transformer N-1 with the largest rated capacity in the 220 kV substation; in formula (2) Indicates the maximum capacity of the main transformer in the 220 kV substation; When the number of main transformers in a substation is equal to 1, the rated capacity of the remaining transformers is 0 after N-1 failures occur in the transformer with the largest rated capacity in a 220 kV substation, that is, , at this time the substation capacity shortage ,in Indicates the load of the substation when the main transformer is N-1.

[0008] Preferably, the step 3 is specifically as follows: When the number of main transformers in a substation is greater than 1, after the N-1 failure of the largest capacity main transformer in a 220 kV substation occurs, the load rate of the substation for: (3); (4); In the formula, It can be a positive value, which indicates that the substation is an off-grid substation; It can also be a negative value, in which case the substation is an on-grid substation; When the number of main transformers in the substation is equal to 1, in order to ensure reliable power supply to the load, energy storage can be configured to meet the power supply demand in a short period of time. At this time, the load rate of the energy storage station is : (5); (6); In the formula, Indicates the configured capacity of energy storage in the energy storage power station.

[0009] Preferably, in step 4, after the N-1 fault occurs in the main transformer of the 220 kV substation, the load transferred from the lower-level 110 kV power grid to the substation is as shown in the following formula: (7); (8); In the formula, It indicates the load that needs to be transferred to ensure that the substation does not overload when the main transformer N-1 with the largest capacity in the substation fails. represents the energy storage output power. When the value is less than 0, it means that the energy storage is in a charging state. When it is greater than 0, it means that the energy storage is in a discharging state. In formula (7), When it is a negative value, It is also a negative value; When is positive, Also positive.

[0010] Preferably, in step 4, to ensure that all 220 kV substations are not overloaded after the load is transferred, When the 220 kV substation is a grid-connected power station (9); In the formula, It represents the load that can be transferred by the j-th 220 kV substation connected with 110 kV line; When the 220 kV substation is an on-grid power station (10).

[0011] Preferably, in step 5, the energy storage capacity The configuration constraints are as follows: (11); (12); Formula (11) indicates that when the energy storage is used as load charging during the off-peak load period, no overload occurs at the main transformer N-1 of the 220 kV substation; Indicates the load value of the substation during the off-peak period; Indicates the charging capacity when the energy storage is charged during the off-peak load period; Indicates the conversion efficiency during the energy storage charging and discharging process, usually between 0.8 and 0.85; It indicates the amount of energy discharged after an N-1 fault occurs in the main transformer of a 220 kV substation during peak load period.

[0012] Preferably, the objective function in step 8 is as follows: (13); Constraints: (14).

[0013] The present invention provides a method for optimizing the configuration of energy storage capacity of a 220 kV substation taking into account the balance of electric power. By configuring energy storage in two scenarios of the substation being online and offline, when the main transformer N-1 with the largest capacity in the substation fails, it can be ensured that the remaining transformers are not overloaded. At the same time, the scenario of a single main transformer in the substation is considered, and the requirements of being online and offline are still met when the main transformer N-1 is. Then, based on the balance of electric power on a typical load day, the energy storage configuration capacity that meets the constraints of electric power balance is analyzed and solved. Finally, the minimum value of the energy storage configuration capacity obtained according to different scenarios is the energy storage configuration capacity of the 220 kV substation, which can meet both the demand of electric power balance and the demand of safe and reliable power supply of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0015] like Figure 1 As shown, the optimal configuration method of energy storage capacity of a 220 kV substation considering power and electricity balance includes the following steps: Step 1, calculate the maximum load rate of the 220 kV substation on a typical load day; Step 2, calculate the rated capacity of the remaining transformers after N-1 faults occur in the main transformer of the substation; Step 3, calculating the load rate after N-1 faults occur in the main transformer of the substation; Step 4, calculate the load transferred by the 110 kV substation after the N-1 fault occurs in the main transformer of the substation; Step 5: Configure energy storage capacity; Step 6: Construct the objective function.

[0016] Preferably, the calculation formula of step 1 is as follows: (1); In the formula, Indicates the maximum load rate under normal operation of the substation. It indicates the maximum load of a typical load day under normal operation of a 220 kV substation. represents the rated capacity of the i-th transformer in the substation, Indicates the number of transformers in the substation.

[0017] Preferably, the step 2 is specifically as follows: When the number of main transformers in the substation is greater than 1, the rated capacity of the remaining transformers after N-1 failures of the substation main transformers As shown below: (2); In the formula, represents the sum of the rated capacities of the remaining transformers after the failure of the transformer N-1 with the largest rated capacity in the 220 kV substation; in formula (2) Indicates the maximum capacity of the main transformer in the 220 kV substation; When the number of main transformers in a substation is equal to 1, the rated capacity of the remaining transformers is 0 after N-1 failures occur in the transformer with the largest rated capacity in a 220 kV substation, that is, , at this time the substation capacity shortage ,in Indicates the load of the substation when the main transformer is N-1.

[0018] Preferably, the step 3 is specifically as follows: When the number of main transformers in a substation is greater than 1, after the N-1 failure of the largest capacity main transformer in a 220 kV substation occurs, the load rate of the substation for: (3); (4); In the formula, It can be a positive value, which indicates that the substation is an off-grid substation; It can also be a negative value, in which case the substation is an on-grid substation; When the number of main transformers in the substation is equal to 1, in order to ensure reliable power supply to the load, energy storage can be configured to meet the power supply demand in a short period of time. At this time, the load rate of the energy storage station is : (5); (6); In the formula, Indicates the configured capacity of energy storage in the energy storage power station.

[0019] Preferably, in step 4, after the N-1 fault occurs in the main transformer of the 220 kV substation, the load transferred from the lower-level 110 kV power grid to the substation is as shown in the following formula: (7); (8); In the formula, It indicates the load that needs to be transferred to ensure that the substation does not overload when the main transformer N-1 with the largest capacity in the substation fails. represents the energy storage output power. When the value is less than 0, it means that the energy storage is in a charging state. When it is greater than 0, it means that the energy storage is in a discharging state. In formula (7), When it is a negative value, It is also a negative value; When is positive, This is also a positive value. At this time, it can include two scenarios: substation on-grid and off-grid.

[0020] The load transfer capacity after the failure of 220 kV main transformer N-1 depends on the 110 kV line connection with other 220 kV substations. Based on the standard "two π and one T" 110 kV connection method between two 220 kV substations, and a 220 kV substation usually has 110 kV connection with 2~3 220 kV substations, the load that can be transferred is analyzed according to the rated capacity of the main transformer of the connected 220 kV substation, and it is necessary to ensure that all 220 kV substations are not overloaded after the load is transferred.

[0021] Preferably, in step 4, to ensure that all 220 kV substations are not overloaded after the load is transferred, When the 220 kV substation is a grid-connected power station (9); In the formula, It represents the load that can be transferred by the j-th 220 kV substation connected with 110 kV line; When the 220 kV substation is an on-grid power station (10).

[0022] 220 kV substations can alleviate the pressure of the 220 kV main transformer supplying load and the pressure of new energy access to the grid by configuring energy storage. At the same time, it can also reduce the load that needs to be transferred after the main transformer N-1 fails and alleviate the pressure of wind and solar power abandonment.

[0023] Preferably, in step 5, the energy storage capacity The configuration constraints are as follows: (11); (12); Formula (11) indicates that when the energy storage is used as load charging during the off-peak load period, no overload occurs at the main transformer N-1 of the 220 kV substation; Indicates the load value of the substation during the off-peak period; Indicates the charging capacity when the energy storage is charged during the off-peak load period; Indicates the conversion efficiency during the energy storage charging and discharging process, usually between 0.8 and 0.85; It indicates the amount of energy discharged after an N-1 fault occurs in the main transformer of a 220 kV substation during peak load period.

[0024] Preferably, the objective function in step 8 is as follows: (13); Constraints: (14).

[0025] According to the method proposed in this patent, it can be calculated that when a 220 kV substation meets both online and offline scenarios, when the main transformer N-1 with the largest capacity in the substation fails, it can ensure that the remaining transformers will not be overloaded, while meeting the power balance under typical load days and meeting the safe and reliable power supply needs of the power grid.

[0026] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for optimizing the energy storage capacity of a 220 kV substation considering power and electricity balance, characterized in that: The following steps are involved: Step 1, calculate the maximum load rate of the 220 kV substation on a typical load day; Step 2, calculate the rated capacity of the remaining transformers after N-1 faults occur in the main transformer of the substation; Step 3, calculating the load rate after N-1 faults occur in the main transformer of the substation; Step 4, calculate the load transferred by the 110 kV substation after the N-1 fault occurs in the main transformer of the substation; Step 5: Configure energy storage capacity; Step 6: Construct the objective function.

2. The 220 kV substation energy storage capacity optimization configuration method considering power and electricity balance according to claim 1 is characterized in that: The calculation formula of step 1 is as follows: (1)； In the formula, Indicates the maximum load rate under normal operation of the substation. It indicates the maximum load of a typical load day under normal operation of a 220 kV substation. represents the rated capacity of the i-th transformer in the substation, Indicates the number of transformers in the substation.

3. The 220 kV substation energy storage capacity optimization configuration method considering power and electricity balance according to claim 2 is characterized in that: The step 2 is specifically as follows: When the number of main transformers in the substation is greater than 1, the rated capacity of the remaining transformers after N-1 failures of the substation main transformers As shown below: (2)； In the formula, represents the sum of the rated capacities of the remaining transformers after the failure of the transformer N-1 with the largest rated capacity in the 220 kV substation; in formula (2) Indicates the maximum capacity of the main transformer in the 220 kV substation; When the number of main transformers in a substation is equal to 1, the rated capacity of the remaining transformers is 0 after N-1 failures occur in the transformer with the largest rated capacity in a 220 kV substation, that is, , at this time the substation capacity shortage ,in Indicates the load of the substation when the main transformer is N-1.

4. The method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance according to claim 3 is characterized in that: The step 3 is as follows: When the number of main transformers in a substation is greater than 1, after the N-1 failure of the largest capacity main transformer in a 220 kV substation occurs, the load rate of the substation for: (3)； (4)； In the formula, It can be a positive value, which indicates that the substation is an off-grid substation; It can also be a negative value, in which case the substation is an on-grid substation; When the number of main transformers in the substation is equal to 1, in order to ensure reliable power supply to the load, energy storage can be configured to meet the power supply demand in a short period of time. At this time, the load rate of the energy storage station is : (5)； (6)； In the formula, Indicates the configured capacity of energy storage in the energy storage power station.

5. The method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance according to claim 4 is characterized in that: In step 4, after the N-1 fault occurs in the main transformer of the 220 kV substation, the load transferred from the lower-level 110 kV power grid to the substation is as shown in the following formula: (7)； (8)； In the formula, It indicates the load that needs to be transferred to ensure that the substation does not overload when the main transformer N-1 with the largest capacity in the substation fails. represents the energy storage output power. When the value is less than 0, it means that the energy storage is in a charging state. When it is greater than 0, it means that the energy storage is in a discharging state. In formula (7), When it is a negative value, It is also a negative value; When is positive, Also positive.

6. The method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance according to claim 5 is characterized in that: In step 4, to ensure that all 220 kV substations are not overloaded after the load is transferred, When the 220 kV substation is a grid-connected power station (9)； In the formula, It represents the load that can be transferred by the j-th 220 kV substation connected with 110 kV line; When the 220 kV substation is an on-grid power station (10)。 7. The method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance according to claim 6 is characterized in that: In step 5, the energy storage capacity The configuration constraints are as follows: (11)； (12)； Formula (11) indicates that when the energy storage is used as load charging during the off-peak load period, no overload occurs at the main transformer N-1 of the 220 kV substation; Indicates the load value of the substation during the off-peak period; Indicates the charging capacity when the energy storage is charged during the off-peak load period; Indicates the conversion efficiency during the energy storage charging and discharging process; It indicates the amount of energy discharged after an N-1 fault occurs in the main transformer of a 220 kV substation during peak load period.

8. The method for optimizing the energy storage capacity of a 220 kV substation considering the power and electricity balance according to claim 7 is characterized in that: The objective function in step 8 is as follows: (13)； Constraints: (14)。

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