Control method and device of flexible distribution area interconnection device

Abstract

Embodiments of the present application provide a control method and device of a flexible transformer area interconnection device, and relate to the technical field of power control. The control method is applied to a control unit in the flexible transformer area interconnection device, the flexible transformer area interconnection device comprising at least one high-frequency isolation unit, a control unit and at least two AC / DC conversion units. The method comprises: obtaining transfer power of at least two transformers in a power distribution network; determining droop coefficients of two AC / DC conversion units associated with each high-frequency isolation unit according to a conversion coefficient of each high-frequency isolation unit; and controlling DC voltages of the at least two AC / DC conversion units according to the droop coefficients of the at least two AC / DC conversion units. Thus, the control method of the flexible transformer area interconnection device provided by the present application simplifies the loop closing control process of the power distribution network, reduces the control cost and improves the control efficiency.

Description

Technical Field

[0001] This application relates to the field of power control technology, and more specifically, to a control method and apparatus for a flexible transformer interconnection device. Background Technology

[0002] With the continuous increase in the electrical load on the power distribution network, both power generation and consumption equipment from new energy sources need to be connected to the distribution network to operate, placing enormous pressure on the operation and management of the existing distribution network. By utilizing the complementary characteristics of the load rates of different transformer substations, an AC / DC interconnected low-voltage distribution network can be constructed. This allows for loop control of the distribution network, achieving load balancing and efficient power supply between different load substations, thus solving the problem of substation overload caused by seasonal and periodic fluctuations.

[0003] To address this issue, current technology allows for phase-locked control of the power distribution network only after the voltage phase in the AC / DC interconnected low-voltage distribution network is locked using a PLL (Phase Locked Loop).

[0004] However, using PLL for phase locking before performing loop control of the power distribution network makes the loop control process extremely complex and cumbersome, and also has the drawbacks of high control cost and low control efficiency. Summary of the Invention

[0005] The purpose of this application is to provide a control method and apparatus for a flexible distribution network interconnection device, in order to address the shortcomings of the prior art and solve the problems of high cost and low control efficiency in the prior art for loop control of power distribution networks.

[0006] To achieve the above objectives, the technical solutions adopted in the embodiments of this application are as follows:

[0007] In a first aspect, embodiments of this application provide a control method for a flexible distribution transformer interconnection device, applied to a control unit in the flexible distribution transformer interconnection device. The flexible distribution transformer interconnection device includes at least one high-frequency isolation unit, a control unit, and at least two AC / DC conversion units; wherein the AC terminals of the at least two AC / DC conversion units are respectively connected to at least two transformers in the power distribution network, and each high-frequency isolation unit is used to perform high-frequency isolation on the DC signals of the AC / DC conversion units connected to the two transformers; the method includes:

[0008] Obtain the transfer power from at least two transformers in the power distribution network;

[0009] Based on the conversion coefficient of each high-frequency isolation unit, determine the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit;

[0010] The DC voltage of the at least two AC / DC conversion units is controlled according to the droop coefficient of the at least two AC / DC conversion units.

[0011] Optionally, determining the droop coefficient of the two AC / DC converters associated with each high-frequency isolation unit based on the conversion coefficient of each high-frequency isolation unit includes:

[0012] The droop coefficient of the two AC / DC conversion units is determined based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit.

[0013] Optionally, determining the droop coefficient of the two AC / DC conversion units based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit includes:

[0014] Based on the safe operating capacity of the two transformers, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units respectively;

[0015] The droop coefficients of the at least two AC / DC conversion units are determined based on the transformer operating coefficients corresponding to the two AC / DC conversion units and the conversion coefficients of each high-frequency isolation unit.

[0016] Optionally, the step of calculating the transformer operating coefficients corresponding to the two AC / DC conversion units based on the safe operating capacity of the two transformers includes:

[0017] Based on the safe operating capacity of the two transformers and the sum of their safe operating capacities, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units.

[0018] Optionally, controlling the DC voltage of the at least two AC / DC converters based on the droop coefficients of the at least two AC / DC converters includes:

[0019] The target DC voltage value of each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter.

[0020] Based on the voltage values ​​at the DC terminals of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the voltage values ​​at the DC terminals of the at least two AC / DC conversion units reach the corresponding target DC voltage values.

[0021] Optionally, the step of calculating the target DC voltage value for each AC / DC converter based on the droop coefficient of each AC / DC converter, a preset DC voltage reference value, and the transfer power of the transformer corresponding to each AC / DC converter includes:

[0022] The initial DC voltage value of each AC / DC conversion unit is calculated based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC conversion unit.

[0023] The target DC voltage value of each AC / DC converter is calculated based on the initial DC voltage value of each AC / DC converter and the detected voltage at the DC terminal of each AC / DC converter.

[0024] Optionally, the step of calculating the target DC voltage value for each AC / DC converter based on the droop coefficient of each AC / DC converter, a preset DC voltage reference value, and the transfer power of the transformer corresponding to each AC / DC converter includes:

[0025] The target DC voltage value of each AC / DC conversion unit is calculated based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the preset variable power value.

[0026] Optionally, the method further includes:

[0027] Obtain the active and reactive power of the current load in the distribution area where each transformer is located;

[0028] Based on the active power of the current load, the reactive power, and the transfer power of each transformer, determine whether each transformer meets the corresponding load demand;

[0029] If the target transformer does not meet the corresponding load demand, it is determined whether the preset fine-tuning condition of the preset change power value is met based on the active power of the current load of the transformer area where the target transformer is located and the active power of the historical load of the transformer area where each transformer is located.

[0030] If the preset fine-tuning conditions of the preset variable power value are met, the preset variable power value is adjusted to obtain a new preset variable power value.

[0031] Based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the new preset variable power value, the target DC voltage value of each AC / DC conversion unit is recalculated.

[0032] Based on the recalculated DC terminal voltage values ​​of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the DC terminal voltage values ​​of the at least two AC / DC conversion units reach the corresponding target DC voltage values.

[0033] Optionally, determining whether each transformer meets the corresponding load demand based on the active power of the current load, the reactive power, and the transfer power of each transformer includes:

[0034] Calculate the current apparent power of each transformer based on the active power and reactive power of the current load;

[0035] The apparent power supplied is calculated based on the power supplied by each transformer and the reactive power loss of the AC-DC conversion unit corresponding to each transformer.

[0036] Determine whether the sum of the current apparent power of each transformer and the apparent power of the transfer is greater than the preset operating capacity of each transformer;

[0037] If the value is less than or equal to the preset operating capacity of each transformer, then each transformer is determined to meet the corresponding load requirement.

[0038] If the load exceeds the preset operating capacity of each transformer, then each transformer is determined to not meet the corresponding load requirement.

[0039] Optionally, determining whether the preset fine-tuning condition for the preset change power value is met based on the current active power of the target transformer area and the historical active power of the transformer area where each transformer is located includes:

[0040] Calculate the power change value of the target transformer load based on the active power of the current load and the active power of the historical load;

[0041] Calculate the power change value of the load and the power ratio of the rated power of the target AC / DC converter unit;

[0042] If the power ratio is less than the preset power ratio threshold, then the preset fine-tuning condition of the preset power value is met.

[0043] If the power ratio is greater than or equal to the preset power ratio threshold, then it is determined that the preset fine-tuning condition of the preset change power value is not met.

[0044] Optionally, the method further includes:

[0045] If the preset fine-tuning conditions for the preset change power value are not met, then the new preset transfer power of the at least two transformers and the new safe operating capacity of the at least two transformers are re-acquired.

[0046] Based on the new safe operating capacity of the at least two transformers and the conversion coefficient of the at least one high-frequency isolation unit, determine the new droop coefficients of the at least two AC-DC conversion units respectively.

[0047] Based on the new droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, and the new power supply of the transformer corresponding to each AC / DC conversion unit, the new target DC voltage value of each AC / DC conversion unit is recalculated.

[0048] Based on the new target DC voltage values ​​of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the voltage values ​​of the DC terminals of the at least two AC / DC conversion units reach the corresponding new target DC voltage values.

[0049] Secondly, embodiments of this application also provide a flexible transformer interconnection device, including: at least two AC / DC conversion units, at least one high-frequency isolation unit, and a control unit;

[0050] The AC terminals of the at least two AC / DC conversion units are respectively connected to at least two transformers in the power distribution network, the DC terminals of two adjacent AC / DC conversion units are respectively connected to the two ends of a high-frequency isolation unit, and the control unit is connected to the control terminals of the at least two AC / DC conversion units.

[0051] The control unit is used to execute the control method of the flexible interconnection device described in any of the first aspects above.

[0052] Compared with the prior art, this application has the following beneficial effects:

[0053] This application provides a control method and apparatus for a flexible distribution network interconnection device. The method involves first acquiring the transfer power of at least two transformers in the distribution network, then determining the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit based on the conversion coefficient of each high-frequency isolation unit, and finally controlling the DC voltage of the at least two AC / DC conversion units based on their droop coefficients. Compared to traditional distribution network loop control methods, the control method for the flexible distribution network interconnection device provided in this application simplifies the loop control process, reduces control costs, and improves control efficiency. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 An electrical connection diagram of a flexible transformer interconnection device provided in an embodiment of this application;

[0056] Figure 2 A schematic diagram illustrating the connection relationship between a high-frequency isolation unit and an AC / DC conversion unit provided in an embodiment of this application;

[0057] Figure 3 An electrical connection diagram of another flexible transformer interconnection device provided in an embodiment of this application;

[0058] Figure 4 A flowchart illustrating a control method for a flexible transformer interconnection device provided in an embodiment of this application;

[0059] Figure 5 A schematic diagram of the control structure of a control method for a flexible transformer interconnection device provided in this application embodiment;

[0060] Figure 6 A schematic diagram of the topology of an AC / DC converter unit provided in an embodiment of this application;

[0061] Figure 7 A flowchart illustrating another control method for a flexible interconnection device for embodiments of this application;

[0062] Figure 8 A schematic diagram illustrating the determination of whether each transformer meets the corresponding load demand in a control method for another flexible distribution area interconnection device provided in an embodiment of this application;

[0063] Figure 9 A schematic diagram illustrating the determination of whether a preset fine-tuning condition for a preset change power value is met in a control method for another flexible interconnection device provided in an embodiment of this application.

[0064] Figure 10 A schematic diagram of a load transfer method for a flexible transformer interconnection device provided in an embodiment of this application;

[0065] Figure 11 A schematic diagram of the control structure of a flexible transformer interconnection device provided in this application embodiment;

[0066] Figure 12This is a schematic diagram of the structure of a control device for a flexible transformer interconnection device provided in an embodiment of this application. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the accompanying drawings in this application are for illustrative and descriptive purposes only and are not intended to limit the scope of protection of this application. Furthermore, it should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this application illustrate operations implemented according to some embodiments of this application. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or implemented simultaneously. In addition, those skilled in the art, guided by the content of this application, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0068] Furthermore, the described embodiments are merely some, not all, of the embodiments of this application. The components of the embodiments of this application described and illustrated herein can typically be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0069] It should be noted that the term "comprising" will be used in the embodiments of this application to indicate the presence of the features declared thereafter, but does not exclude the addition of other features.

[0070] To simplify the process of loop control of power distribution networks, reduce control costs, improve control efficiency, and ensure the stable and reliable operation of power distribution networks, this application provides a control method and device for a flexible distribution transformer interconnection device. This device adjusts the load transfer power in the power distribution network in real time to ensure the stable and reliable operation of the power distribution network and reduce the cost of loop control of the power distribution network.

[0071] To clearly describe the control method of the flexible transformer interconnection device provided in the embodiments of this application, the flexible transformer interconnection device will be described in detail with reference to the accompanying drawings. Figure 1 This is a schematic diagram of the electrical connection of a flexible transformer substation interconnection device provided in an embodiment of this application. Figure 1 As shown, the flexible transformer interconnection device 100 includes: at least one high-frequency isolation unit 101, a control unit 102, and at least two AC / DC conversion units 103.

[0072] Each high-frequency isolation unit 101 is used to provide high-frequency isolation for the DC signal of the AC-DC conversion unit 103 connected to two transformers. The AC terminals of at least two AC-DC conversion units 103 are respectively connected to at least two transformers in the planned closed-loop distribution network, and the DC terminals of two adjacent AC-DC conversion units 103 are respectively connected to the two ends of a high-frequency isolation unit 101. The control unit 102 is connected to the control terminals of at least two AC-DC conversion units 103 and the control terminal of at least one high-frequency isolation unit 101.

[0073] The AC / DC conversion unit 103 can be an AC / DC converter. Each AC / DC conversion unit 103 has a preset power protection limit to prevent excessive circulating current during the closed-loop control of the power distribution network. For example, if the preset power protection limit of the AC / DC converter is 100kW, then the AC / DC converter will stop operating after the protection current exceeds a preset multiple (e.g., 1.2 times) and a preset stop time (e.g., 1 minute). The preset multiple of the protection current can be set according to actual conditions; the preset stop time can be set according to the actual overload capacity of the power distribution network.

[0074] Each AC / DC conversion unit 103 has its AC terminal connected to the AC bus of one transformer in the planned closed-loop distribution network. Adjacent AC / DC conversion units 103 are DC interconnected via a high-frequency isolation unit. Since the AC terminal of each AC / DC conversion unit 103 is connected to one transformer in the planned closed-loop distribution network, the number of AC / DC conversion units in practical flexible distribution network interconnection applications depends on the number of transformers in the planned closed-loop distribution network. The number of AC / DC conversion units in the flexible distribution network interconnection device is at least greater than or equal to the number of transformers in the planned closed-loop distribution network.

[0075] Continue to refer to Figure 1 The high-frequency isolation unit 101 can be a transformer or converter with high-frequency isolation function, such as a high-frequency isolation transformer or a high-frequency isolation DC / DC converter. No limitation is made here, and those skilled in the art can choose according to the actual situation. In practical applications, each high-frequency isolation unit can consist of at least one isolation unit; if there are multiple isolation units, they are connected in series.

[0076] Figure 2 This is a schematic diagram illustrating the connection relationship between a high-frequency isolation unit and an AC / DC conversion unit, provided as an embodiment of this application. Figure 2As shown in Figure A, the high-frequency isolation unit 101 may include two isolation units connected in series. One isolation unit 101-1 is connected to the DC terminal of the AC / DC converter 103-1, and the other isolation unit 101-2 is connected to the DC terminal of another AC / DC converter 103-2. When the high-frequency isolation unit 101 has two isolation units, each isolation unit can be integrated into a corresponding housing as part of a correspondingly connected AC / DC converter.

[0077] It should be noted that, Figure 2 A is merely a schematic diagram showing the connection between the two high-frequency isolation units 101 and the DC terminals of the two AC / DC conversion units 103. Figure 2 B represents the connection relationship between a high-frequency isolation unit 101 and two adjacent AC / DC conversion units 103. The connection relationships between other high-frequency isolation units and their corresponding AC / DC conversion units in the flexible transformer interconnection device will not be described here.

[0078] In other examples, if the high-frequency isolation unit 101 includes only one isolation unit, then the isolation unit and the corresponding AC / DC conversion unit 103 are respectively housed in their respective housings.

[0079] To clearly describe the flexible transformer interconnection device provided in the embodiments of this application, the following embodiments will all use the following terms: Figure 2 The connection relationship between the high-frequency isolation unit and the AC / DC conversion unit of unit B is used as an example for explanation. Since the two ends of a high-frequency isolation unit 102 are respectively connected to the DC terminals of two adjacent AC / DC conversion units 101, then for N AC / DC conversion units 101, N-1 high-frequency isolation units 102 are required. Here, N is an integer greater than or equal to 2. Therefore, the flexible transformer interconnection device can also be called a high-frequency isolation type flexible transformer interconnection device, or a high-frequency isolation type flexible transformer interconnection system.

[0080] In addition to the AC / DC conversion unit and high-frequency isolation unit described above, the flexible transformer interconnection device also includes a control unit that can be connected to the control terminal of each AC / DC conversion unit to control each AC / DC conversion unit.

[0081] Continue to refer to Figure 1The high-frequency isolation unit 101 has an inverse-time overcurrent protection function, i.e., a short-circuit inverse-time protection function. The control unit 102 can be connected to the control terminal of the high-frequency isolation unit 101 to obtain the impedance values ​​of the DC lines of the two DC terminals of the high-frequency isolation unit 101. Based on the DC bus voltage and corresponding impedance values ​​of the two DC terminals of the high-frequency isolation unit 101, it determines whether there is a short circuit inside the high-frequency isolation unit 101. If a short circuit exists, it controls the protection device in the high-frequency isolation unit 101 to perform protection actions.

[0082] For example, the control unit 102 first calculates the line impedance of the two DC terminals of the high-frequency isolation unit 101, such as the minimum line impedance value Z. dc_min Or the per-unit value of the line impedance Z * dc_min Then the control unit 102 can determine the DC bus voltage U at the DC terminal of the high-frequency isolation unit 101. dc Divide by the line impedance value, such as the minimum line impedance value Z. dc_min Then the current threshold of the DC terminal of the high-frequency isolation unit 101 can be obtained:

[0083]

[0084] Given the calculated DC threshold of the DC terminal of the high-frequency isolation unit 101, the DC current i at the DC terminal of the high-frequency isolation unit 101 is... dc Monitoring is performed when the DC current i of the monitored high-frequency isolation unit 101 is... dc If the current is greater than or equal to the current threshold, it can be determined that there is a short circuit risk inside the high-frequency isolation unit 101. The risk can then be determined based on the monitored DC current i of the high-frequency isolation unit 101. dc Control the internal protective devices to perform protective actions.

[0085] If the DC terminal of the high-frequency isolation unit 101 is not connected to a load or other DC system, the minimum line impedance value can be used as the line impedance; if the DC terminal of the high-frequency isolation unit 101 is connected to a load or other DC system such as a DC power generation system, the per-unit value of the line impedance can be used as the line impedance.

[0086] The operating time of the protection device in the high-frequency isolation unit 101 automatically decreases as the monitored DC current increases. The relationship between the protection time t of the inverse-time overcurrent protection function and the current is shown in formula (1):

[0087]

[0088] Among them, t p The preset constant value for the inverse time overcurrent time; I SC To measure the overcurrent value of the circuit under test in the high-frequency isolation unit 101; IP This is the preset starting current value for overcurrent protection.

[0089] Therefore, it can be known that if the high-frequency isolation unit 101 is short-circuited, the DC current i at the DC terminal of the high-frequency isolation unit 101 will be monitored. dc The larger the value, the faster the control unit 102 will execute the protection device of the high-frequency isolation unit 101.

[0090] In summary, the flexible distribution network interconnection device provided in this application embodiment can control each AC / DC conversion unit through the control unit to achieve loop control of the distribution network, suppressing the circulating current hazards generated during the loop control process. At the same time, the use of a high-frequency isolation unit to interconnect two adjacent AC / DC conversion units reduces the cost of the flexible distribution network interconnection device. Furthermore, the control unit does not need to use a PLL for phase locking before loop control, thereby simplifying the loop control process of the distribution network, improving the efficiency of the loop control, and reducing the cost of the loop control.

[0091] Secondly, in this embodiment, since the high-frequency isolation unit in the flexible transformer interconnection device has a built-in short-circuit inverse time protection function, the high-frequency isolation unit can be controlled by the control unit to realize the protection of the DC end of the high-frequency isolation unit. This solves the problem that the DC end of the high-frequency isolation unit has a short circuit and is difficult to protect quickly. At the same time, a DC load or DC power generation system, such as a new energy DC power generation device, can be added to the DC end of the high-frequency isolation unit.

[0092] The following is a detailed description of an example of a flexible transformer interconnection device for loop control of two transformers, provided in conjunction with the accompanying drawings. Figure 3 This is a schematic diagram of the electrical connection of another flexible transformer substation interconnection device provided in an embodiment of this application. Figure 3 In the example, the flexible transformer interconnection device 200 may include: a high-frequency isolation unit 201, a control unit 202, an AC / DC conversion unit 203-1, and an AC / DC conversion unit 203-2. The AC terminal of the AC / DC conversion unit 203-1 is connected to the AC bus of transformer #1, and the AC terminal of the AC / DC conversion unit 203-2 is connected to the AC bus of transformer #2. The control unit 202 is connected to the control terminal of the high-frequency isolation unit 202, the DC terminal of the AC / DC conversion unit 203-1, and the DC terminal of the AC / DC conversion unit 203-2. Therefore, the AC / DC conversion units 203-1 and 203-2 can achieve DC interconnection of the flexible transformer interconnection device 200 through a single high-frequency isolation unit 201.

[0093] The control method executed by the control unit in the flexible distribution area control device provided in the above embodiments of this application will be explained and described in detail below with reference to the accompanying drawings. Figure 4This is a flowchart illustrating a control method for a flexible transformer interconnection device provided in an embodiment of this application. Figure 4 As shown, the method includes:

[0094] S301. Obtain the transfer power of at least two transformers in the power distribution network.

[0095] Specifically, obtaining the transfer power of each transformer in the planned closed-loop distribution network means obtaining the electrical power that can meet the load demand of each transformer, that is, obtaining the real-time active power P transferred by transformers in different sections of the planned closed-loop distribution network. S For example, the transfer power of each transformer can be obtained from the power dispatching system corresponding to at least two transformers; alternatively, the transfer power of each transformer can be calculated using a preset power load prediction algorithm. The preset power load prediction algorithm, such as the load derivative method, similarity day method, Kalman filter method, exponential smoothing method, or grey prediction method, is not limited here, and those skilled in the art can choose according to the actual situation. For example, the active power P that needs to be transferred to the transformer area #1... s1 The adjacent No. 2 transformer area has P s2 The active power can be transferred to the No. 1 transformer area, so that the transferred power meets the load demand of the transformer area that needs to be transferred. The active power between different transformer areas can be transferred to each other.

[0096] S302. Based on the conversion coefficient of each high-frequency isolation unit, determine the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit.

[0097] Among them, the conversion coefficient K of the high-frequency isolation unit C The ratio of the voltages on both sides of the DC terminal of the two AC / DC converters associated with each high-frequency isolation unit.

[0098] To clearly describe the calculation process of the target DC voltage value in the control method of the flexible transformer interconnection device provided in this application embodiment, it will be described in detail with reference to the accompanying drawings. Figure 5 This is a schematic diagram of the control structure of a control method for a flexible transformer interconnection device provided in an embodiment of this application.

[0099] exist Figure 5In the example, the control structure 400 of the control method for the flexible transformer substation interconnection device includes: load Z1 under transformer substation #1 and load Z2 under transformer substation #2, line impedance LG1 under transformer substation #1 and line impedance LG2 under transformer substation #2, high-frequency isolation unit 401, control unit 402, and AC / DC conversion unit 403. The control unit 402 includes: DC droop control loops 402-A1 and 402-B1, PI regulators 402-A2 and 402-B2, current inner loop transfer function 402-A3 and 402-B3, and intelligent computing modules 402-A4 and 402-B4. It should be noted that all modules in the control unit 402 are identical; for ease of understanding, they are represented by A and B.

[0100] At this time, the conversion coefficient K of the high-frequency isolation unit 401 C The conversion coefficient K of the high-frequency isolation unit 401 is the voltage ratio across the DC terminals of the AC / DC conversion units 403-1# and 403-2# associated with the high-frequency isolation unit 401. It can be calculated using the following formula (2). C :

[0101]

[0102] Among them, U dc1 U is the voltage at the DC terminal of the AC / DC converter unit 403-1# associated with the high-frequency isolation unit 401. dc2 The voltage at the DC terminal of the AC / DC conversion unit 403-2# associated with the high-frequency isolation unit 401.

[0103] In other words, the conversion coefficient K of each high-frequency isolation unit C That is, the voltage ratio across the DC terminals of the two AC / DC converters associated with each high-frequency isolation unit, thereby determining the droop coefficient K corresponding to each AC / DC converter associated with each high-frequency isolation unit. P .

[0104] S303. Control the DC voltage of at least two AC / DC conversion units based on the droop coefficient of at least two AC / DC conversion units.

[0105] After performing step S302 above, the droop coefficient K of at least two AC / DC conversion units can be used as a basis. P The DC voltage of at least two AC / DC conversion units is controlled. For example... Figure 5 As shown, if the voltage U at the DC terminal of the AC / DC conversion unit 403-1# associated with the high-frequency isolation unit 401 is... dc1The voltage U at the DC terminal of the AC / DC converter unit 403-2# associated with the high-frequency isolation unit 401 is greater than that of the high-frequency isolation unit 401. dc1 When this occurs, it indicates that transformer #1 can transfer active power P to transformer #2. S The power supply; if the voltage U at the DC terminal of the AC / DC conversion unit 403-1# associated with the high-frequency isolation unit 401 is... dc1 The voltage U at the DC terminal of the AC / DC converter unit 403-2# associated with the high-frequency isolation unit 401 is less than that of the high-frequency isolation unit 401. dc1 When this occurs, it indicates that transformer #2 can transfer active power P to transformer #1. S The transfer of power allows the DC voltage of at least two AC / DC conversion units 403 to achieve voltage balance.

[0106] In summary, the control method for the flexible distribution transformer interconnection device provided in this application embodiment can first obtain the transfer power of at least two transformers in the distribution network, then determine the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit based on the conversion coefficient of each high-frequency isolation unit, and finally control the DC voltage of at least two AC / DC conversion units based on the droop coefficients of the at least two AC / DC conversion units. The control method for the flexible distribution transformer interconnection device provided in this embodiment simplifies the process of loop-closing control of the distribution network, reduces control costs, and improves control efficiency.

[0107] In some embodiments of this application, the droop coefficient of the two AC / DC converters associated with each high-frequency isolation unit is determined based on the conversion coefficient of each high-frequency isolation unit, including:

[0108] The droop coefficients of the two AC / DC conversion units are determined based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit.

[0109] The safe operating capacity of the transformer is a pre-set capacity value for safe operation, which can be represented by S. i Let S be used to represent this. i The safe operating capacity of the i-th transformer connected to the AC terminal of the flexible distribution area interconnection device, where i can take values ​​(1,2,3,…,n).

[0110] Specifically, the safe operating capacity S of the two transformers connected to the two AC / DC conversion units can be used as a reference. i And the conversion coefficient K of each high-frequency isolation unit C Determine the droop coefficient K of the two AC / DC conversion units. P Due to the safe operating capacity S of each transformer i The droop coefficient K of the corresponding AC / DC converter unit P The difference is that the safe operating capacity S of the transformer is different.i When the change occurs, the droop coefficient K of the corresponding AC / DC converter unit P This also changes accordingly; that is, the droop coefficient K of the AC / DC conversion unit... P The safe operating capacity S of the transformer can be adjusted accordingly. i It changes with the changes.

[0111] In this embodiment, the droop coefficient K of the AC / DC conversion unit corresponding to each transformer is determined. P During the process, compared with obtaining the DC current flowing through the transformer or the impedance, the safe operating capacity S of the transformer is obtained. i It is simpler, and its calculation of the droop coefficient K P The process is also simpler.

[0112] Continuing with the above Figure 3 In practical applications, the safe operating capacity S1 of transformer #1 and the safe operating capacity S2 of transformer #2, as well as the conversion coefficient K of the high-frequency isolation unit located between AC / DC conversion unit 203-1 and AC / DC conversion unit 203-2, can be used as the reference. C Determine the droop coefficient K corresponding to AC / DC conversion unit 203-1 respectively. P1 The droop coefficient K corresponding to AC / DC conversion unit 203-2 P2 .

[0113] In some embodiments of this application, the droop coefficient of the two AC / DC conversion units is determined based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit, including:

[0114] Based on the safe operating capacity of the two transformers, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units respectively;

[0115] Based on the transformer operating coefficients corresponding to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit, the droop coefficients of at least two AC / DC conversion units are determined respectively.

[0116] For example, the transformer operating coefficient K corresponding to the two AC / DC conversion units can be used as a reference. S Preset high-frequency isolation unit conversion coefficient K C And the preset reliability coefficient K T Determine the droop coefficient K for at least two AC / DC conversion units respectively. P In other words, in practical applications, the conversion coefficient K of the preset high-frequency isolation unit can be used as a reference. C The transformer operating factor K corresponding to at least two AC / DC conversion units S And the preset reliability coefficient K TThe droop coefficient K of at least two AC / DC converter units is calculated using the following formula (2). P .

[0117] K P =K T *K C *K S Formula (2)

[0118] Among them, K T The preset reliability factor K is the reliability factor for the flexible distribution network interconnection device. T The preset voltage value U at the DC terminal of the AC / DC conversion unit dcs The reliability coefficient K is related to the operating range. T The selected value must ensure that the preset voltage value U at the DC terminal of the AC / DC converter unit is met. dcs Operating within a preset operating voltage range, i.e., the preset voltage U at the DC terminal of the AC / DC converter unit. dcs The preset operating voltage range is [U dcmin U dcmax The preset voltage value U at the DC terminal of the AC / DC conversion unit is... dcs It can be calculated using a preset voltage outer loop control algorithm.

[0119] It should be noted that the reliability coefficient K T As an empirical data point, when calculating the protection action value of the distribution network loop control, the calculation result is multiplied by a reliability coefficient to ensure the accuracy and reliability of the protection action of the distribution network loop control. Its empirical value can be [1, 0.5, 0.4, 0.3, 0.2, 0.1].

[0120] In some embodiments of this application, as shown above, the transformer operating coefficients corresponding to the two AC / DC conversion units are calculated based on the safe operating capacity of the two transformers, including:

[0121] Based on the safe operating capacity S of each transformer i And the sum of the safe capacities of the two transformers, S n Calculate the transformer operating coefficient K for each of the two AC / DC conversion units. S .

[0122] For example, it can be based on the safe operating capacity S of each transformer. i And the sum of the safe capacities of the two transformers, S n The transformer operating factor K corresponding to an AC / DC conversion unit connected to each transformer can be calculated using the following formula (3). S .

[0123]

[0124] In existing technology, the transformer operating coefficient K S The calculations are usually performed using the current or impedance in the power system, which is complex and difficult to obtain; however, this application uses the safe operating capacity S of each transformer. i To obtain the running system K S Its acquisition and calculation process is both simple and convenient.

[0125] Therefore, according to the descriptions of formulas (2) and (3), the droop system K corresponding to the AC / DC converter unit P The value can be set according to the safe operating capacity S of the transformer. i It changes with the changes, and at the same time, the AC / DC conversion unit can use the droop coefficient K. P The control method is used to regulate the voltage fluctuation at the DC end of the AC / DC conversion unit, so that the load charge of each transformer connected by the flexible distribution area interconnection device reaches a balanced state.

[0126] In some embodiments of this application, controlling the DC voltage of at least two AC / DC converters based on the droop coefficients of at least two AC / DC converters includes:

[0127] The target DC voltage value for each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter.

[0128] Based on the voltage values ​​at the DC terminals of at least two AC / DC conversion units, control is applied to at least two AC / DC conversion units respectively, so that the voltage values ​​at the DC terminals of at least two AC / DC conversion units respectively reach the corresponding target DC voltage values.

[0129] In one possible implementation, the control unit in the flexible transformer interconnection device can adjust the voltage U at the DC terminal of each AC / DC conversion unit according to a preset voltage value U. dcs Or preset DC voltage reference value U ref Control at least two AC / DC converter units respectively, so that the DC terminal voltage values ​​of at least two AC / DC converter units reach the corresponding target DC voltage value U. dc .

[0130] Continuing with the above Figure 5 The preset voltage value U at the DC terminal of the AC / DC conversion unit 403-1# is determined. dcs The preset DC reference voltage U at the DC terminal of AC / DC conversion unit 403-2# has changed. refThe load remains unchanged, thus enabling the transfer of power load from transformer area #1 to transformer area #2, or vice versa. Therefore, the real-time active power P transferred to the transformer area can be determined. s The direction allows for the measurement of active power P between different transformer substations. s The mutual transfer of power, that is, the active power P that needs to be transferred from the No. 1 transformer area. s1 The adjacent transformer substation #2 has P. s1 The active power can be transferred to the No. 1 transformer area, thereby achieving the goal of supplying power to meet the load demand of the transformer area that needs to be supplied.

[0131] It should be noted that when more than two flexible transformer substations are interconnected, the AC / DC conversion unit under each transformer substation can be independently configured with active power P. s , drooping system K p and preset DC voltage reference value U ref And ensure that at least one AC / DC conversion unit is equipped with a preset DC voltage reference value U. ref .

[0132] In some embodiments of this application, the target DC voltage value of each AC / DC converter is calculated based on the droop coefficient corresponding to each AC / DC converter, a preset DC voltage reference value, and the power supplied by the transformer corresponding to each AC / DC converter, including:

[0133] The initial DC voltage value of each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter.

[0134] The target DC voltage value of each AC / DC converter is calculated based on the initial DC voltage value of each AC / DC converter and the detected voltage at the DC terminal of each AC / DC converter.

[0135] Specifically, continuing to combine the above Figure 5 The control unit 402 determines the droop coefficient K corresponding to each AC / DC conversion unit. p Preset DC voltage reference value U ref The power P supplied by the transformer corresponding to each AC / DC conversion unit s Calculate the initial DC voltage value U for each AC / DC conversion unit. dc初 ;

[0136] The control unit 402 then determines the DC voltage value U of each AC / DC converter unit. dc初 And the DC terminal detection voltage U of each AC / DC converter unit dc检Calculate the target DC voltage value U for each AC / DC converter unit. dc That is, the target DC voltage value U. dc With the initial DC voltage value U dc初 and DC terminal detection voltage U dc检 The calculation relationship satisfies the following formula (4):

[0137] U dc =U dc检 -U dc初 Formula (4)

[0138] Wherein, if the target DC voltage value U of the AC / DC conversion unit dc When the value is positive, it can be determined that the AC / DC conversion unit can provide active power P to the transformer area corresponding to its adjacent AC / DC conversion unit. s The AC / DC converter unit supplies the DC voltage. If the target DC voltage value U of the AC / DC converter unit... dc When the value is negative, it can be determined that the AC / DC conversion unit requires the active power P supplied by the transformer substation corresponding to its adjacent AC / DC conversion unit. s .

[0139] For example, the target DC voltage value U of AC / DC conversion unit 403-1# dc When the value is positive, it can be determined that AC / DC conversion unit 403-1# can provide active power P to the transformer area corresponding to AC / DC conversion unit 403-2#. s The power supply is transferred to meet the load demand of the transformer area requiring power transfer. If the target DC voltage value U of AC / DC conversion unit 403-1# is... dc When the value is negative, it can be determined that AC / DC conversion unit 403-1# requires the active power P transferred from the transformer area corresponding to AC / DC conversion unit 403-2#. s The power supplied will meet the load requirements of the No. 1 transformer area.

[0140] The following figure, in conjunction with the accompanying drawings, also provides an example of the topology of an AC / DC converter unit. Figure 6 This is a schematic diagram of the topology of an AC / DC converter unit provided in an embodiment of this application.

[0141] like Figure 6 As shown, the key component in the AC / DC converter topology 51 is the AC / DC converter module 51-1, which mainly realizes the AC to DC conversion of the AC / DC converter. The capacitor current at the DC end of the AC / DC converter satisfies i c =i dc -i h The relationship, where i dc i is the inner loop current of the DC-DC converter unit. hThis is the input current of the AC / DC conversion unit.

[0142] Continuing with the above Figure 5 Specifically, voltage U is sampled from the DC terminal of AC / DC conversion unit 403-1#. dc1 The subtraction operation is performed, and the data is transmitted to the PI regulator 402-A2, outputting the inner loop current reference value i of the active power of the AC-DC converter unit 403-1#. * d1 Then, the inner loop current i of the AC-DC converter unit 403-1# is output through the inner loop transfer function 403-A3. dc1 Inner loop current i dc1 The input current i of AC / DC converter unit 403-1# h1 The capacitor current i at the DC terminal of AC / DC converter unit 403-1# is obtained. c1 Finally, the intelligent computing module 402-A4 obtains the target DC voltage value U output by the AC / DC conversion unit 403-1#. dc1 value.

[0143] Meanwhile, the preset DC voltage reference value U is directly provided by the DC droop control loop 402-B1. ref The voltage U is sampled from the DC terminal of AC / DC converter unit 403-1#. dc1 The subtraction operation is performed, and the output of the subtraction operation is passed to the PI regulator 402-B2, which outputs the inner loop current reference value i of the active power of the AC-DC converter unit 403-2#. * d2 Then, the inner loop current i of the AC-DC converter unit 403-2# is output through the inner loop transfer function 402-B3. dc2 Inner loop current i dc2 The input current i of AC / DC converter unit 403-2# h2 The capacitor current i at the DC terminal of AC / DC converter unit 403-2# is obtained. c2 Finally, the intelligent computing module 402-B4 obtains the target DC voltage value U output by the AC / DC conversion unit 403-2#. dc2 value.

[0144] It should be noted that the active power P required by the load in the transformer area of ​​transformer #2 is to be transferred and supplied. s It depends on whether the AC / DC conversion unit 403-1# performs active power transfer P. s To make adjustments, it is necessary to determine whether the control unit 402 should input the DC droop control loop 402-B1 for use; at the same time, the active power P transferred from the No. 1 transformer area should also be adjusted. sThe active power is compared with the transfer capacity PT2 of AC / DC converter 403-2#. If it is greater than PT2, the active power is transferred according to the transfer capacity PT2 of AC / DC converter 403-2#, and this value is input into the DC droop control loop 402-B1. If it is less than PT2, the active power is transferred according to the transfer capacity PT1 of AC / DC converter 403-1#, and this value does not need to be input into the DC droop control loop 402-B1. If it is equal to PT2, the power load of AC / DC converter 403-1# and AC / DC converter 403-2# is balanced, and no active power P needs to be transferred. s Therefore, the transfer of power does not need to be input into the DC droop control loop 402-B1. The transfer capacity refers to the transfer load that can be utilized or the transfer capacity that can be provided by neighboring user groups when the power system is affected by an outage.

[0145] In some embodiments of this application, as shown above, the target DC voltage value of each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, a preset DC voltage reference value, and the power supplied by the transformer corresponding to each AC / DC converter, including:

[0146] The target DC voltage value for each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC converter, and the preset variable power value.

[0147] Continuing with the above Figure 5 The control unit 402 determines the droop coefficient K corresponding to each AC / DC conversion unit. p Preset DC voltage reference value U ref The power output P of the transformer corresponding to each AC / DC conversion unit s Calculate the target DC voltage value U for each AC / DC converter unit. dc .

[0148] Specifically, when the AC / DC converter unit 403 operates in DC droop mode, the droop coefficient K p Real-time transfer of active power P between different transformer substations in the flexible distribution interconnection device 400 s And the preset voltage value U at the DC terminal of AC / DC conversion unit 403-1# dcs The preset DC voltage reference value U at the DC terminal of AC / DC conversion unit 404-2# ref The relationship between them is shown in formula (5):

[0149] U dcs -U ref =-K P P s+ΔP Formula (5)

[0150] Among them, the active power P supplied by the transfer s and the drooping system K p For the calculated value, a preset DC voltage reference value U is used. ref Given a value, the droop coefficient K P The value range is [0, 100%].

[0151] The calculated preset voltage value U of the AC / DC converter unit dcs Or the target DC voltage value U of the AC / DC conversion unit dc Or the preset DC voltage reference value U ref The operating voltage value must be within the range of the DC terminal of the AC / DC converter unit [U] dcmin U dcmax ]Inside.

[0152] It should be noted that in the flexible distribution network interconnection device, in addition to the DC terminal voltage of the AC / DC conversion unit 403-1# described above being a preset voltage value U, dcs Therefore, the voltage value at the DC terminal of AC / DC conversion unit 403-2# is the preset reference voltage value U. ref In addition, the voltage value at the DC terminal of AC / DC conversion unit 403-1# is the reference voltage value U. ref In this case, the target DC voltage value U of the AC / DC conversion unit 403 is calculated. dc The method is the same, so I won't go into details here.

[0153] In summary, the control method for the flexible distribution transformer interconnection device provided in this application can obtain the transfer power and safe operating capacity of at least two transformers in the planned closed-loop distribution network, and determine the droop coefficient of at least two AC / DC conversion units based on the safe operating capacity of the at least two transformers. Based on the droop coefficient corresponding to each AC / DC conversion unit, a preset DC voltage reference value, and the transfer power of the transformer corresponding to each AC / DC conversion unit, the target DC voltage value of each AC / DC conversion unit is calculated. Then, based on the DC voltage values ​​of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the DC terminal voltage values ​​of the at least two AC / DC conversion units reach the corresponding target DC voltage values. The control method provided in this embodiment can realize load transfer between different transformer distribution transformer areas using the flexible distribution transformer interconnection device, achieving load balancing in different transformer distribution transformer areas. Simultaneously, the load transfer power can be adjusted in real time by adjusting relevant parameters in the DC droop mode, solving the problem of load capacity expansion between transformer distribution transformer areas and providing safety assurance for the DC interconnection of the flexible distribution transformer interconnection device.

[0154] Based on the above embodiments, this application also provides a control method for a flexible transformer interconnection device, which will be further described below with reference to the accompanying drawings. Figure 7 This is a flowchart illustrating another control method for a flexible transformer interconnection device, as provided in the embodiments of this application. Figure 7 As shown, the method may further include the following steps:

[0155] S601. Obtain the current active and reactive power of the load in the transformer substation where each transformer is located.

[0156] Specifically, the current active power P and reactive power Q of the load in the transformer substation can be obtained by acquiring the current active power P and reactive power Q of the load from the acquisition equipment on the transformer substation through an AC / DC conversion unit. The acquisition equipment can be a meter or a concentrator; there are no restrictions, and those skilled in the art can choose according to the actual situation.

[0157] S602. Based on the current active power, reactive power, and power supplied by each transformer, determine whether each transformer meets the corresponding load demand. If the corresponding load demand is met, proceed to step S603; otherwise, proceed to step S604.

[0158] Specifically, based on the current load active power P and reactive power Q obtained in step S601 above, and the transfer power P of each transformer obtained through the power dispatching system or a preset power load prediction algorithm, s This determines whether each transformer meets the corresponding load requirements.

[0159] S603. If each transformer currently meets its corresponding load demand, then the execution ends.

[0160] S604. If the target transformer does not meet the corresponding load demand, determine whether the preset fine-tuning conditions for the preset power change value are met based on the current active power of the load in the transformer area where the target transformer is located and the historical active power of the load in the transformer area where each transformer is located. If the preset fine-tuning conditions for the preset power change value are met, proceed to step S605; if the preset fine-tuning conditions for the preset power change value are not met, proceed to step S608. The preset fine-tuning conditions can be set according to the actual situation.

[0161] S605. If the preset fine-tuning conditions for the preset variable power value are met, the preset variable power value is adjusted to obtain a new variable power value P. 新 .

[0162] Specifically, if the target transformer does not meet the corresponding load demand, the current active power P of the transformer substation where the target transformer is located will be used as the basis for determining the load demand. 当前and the historical active power P of the load in the distribution area where each transformer is located 历史 Determine whether the preset fine-tuning conditions for the preset power change value ΔP are met. Continue combining the above... Figure 5 If transformer substation #2 needs to transfer power to transformer substation #1, meaning the target transformer is transformer #1, then the current active power P of transformer substation #1 is... 当前1 and the historical active power P of the load in the distribution area where each transformer is located 历史1 Does the difference satisfy the preset fine-tuning condition of the preset power change value ΔP?

[0163] If the current active power P of the load in the transformer area of ​​transformer #1 当前1 and the historical active power P of the load in the distribution area where each transformer is located 历史1 If the difference satisfies the preset fine-tuning condition of the preset change power value ΔP, then the preset change power value ΔP is adjusted to obtain a new change power value P. 新 .

[0164] S606. Based on the droop coefficient corresponding to each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the new preset variable power value, recalculate the target DC voltage value for each AC / DC conversion unit.

[0165] Specifically, continuing to combine the above Figure 5 The control unit 403 determines the droop coefficient K corresponding to each AC / DC conversion unit. P Preset DC voltage reference value U ref The power P supplied by the transformer corresponding to each AC / DC conversion unit s And the new preset variable power value ΔP 新 Recalculate the target DC voltage value U for each AC / DC converter unit. dcs Continue to recalculate the target DC voltage value U for each AC / DC converter unit using the above formula (5). dcs , that is U dcs =-K P P s +ΔP 新 +U ref .

[0166] S607. Based on the recalculated DC voltage values ​​of at least two AC / DC conversion units, control at least two AC / DC conversion units respectively, so that the voltage values ​​at the DC terminals of at least two AC / DC conversion units respectively reach the corresponding target DC voltage values.

[0167] Specifically, continuing to combine the above Figure 5 The control unit 403 calculates the DC voltage value U from at least two AC / DC conversion units.dcs Control at least two AC / DC converter units respectively, so that the voltage value at the DC terminal of at least two AC / DC converter units reaches the corresponding target DC voltage value U. dc .

[0168] S608. If the preset fine-tuning conditions for the preset change power value are not met, then the new transfer power of at least two transformers and the new safe operating capacity of at least two transformers shall be obtained again.

[0169] S609. Based on the new safe operating capacity of at least two transformers, determine the new droop coefficients corresponding to at least two AC / DC conversion units respectively.

[0170] S610. Based on the new droop coefficient corresponding to each AC / DC conversion unit, the preset DC voltage reference value, and the new power supply of the transformer corresponding to each AC / DC conversion unit, recalculate the new target DC voltage value for each AC / DC conversion unit.

[0171] S611. Based on the new target DC voltage values ​​of at least two AC / DC conversion units, control at least two AC / DC conversion units respectively, so that the voltage values ​​of the DC terminals of at least two AC / DC conversion units respectively reach the corresponding new target DC voltage values.

[0172] Specifically, if the preset fine-tuning conditions for the preset variable power value ΔP are not met, the control unit in the flexible transformer interconnection device needs to recalculate the new target DC voltage value U for each AC / DC converter unit. dc新 And control at least two AC / DC conversion units respectively, so that the voltage value of the DC terminal of at least two AC / DC conversion units reaches the corresponding new target DC voltage value U. dc新 .

[0173] It should be noted that the embodiment of the control method for another flexible transformer interconnection device mentioned above is only for illustrating the implementation of this application and should not be construed as a limitation of this application. In other examples, implementation methods, or embodiments, the method can be selected according to this application, and no specific limitation is made here.

[0174] In the above embodiments Figure 7 Based on this, the embodiments of this application also provide an example of another control method for flexible transformer interconnection devices to determine whether each transformer meets the corresponding load requirements, which will be further described below with reference to the accompanying drawings. Figure 8 This is a schematic diagram of S603, which describes the determination of whether each transformer meets the corresponding load requirement in the control method of another flexible transformer interconnection device provided in this application embodiment.

[0175] S701. Calculate the current apparent power of each transformer based on the current active and reactive power of the load.

[0176] Specifically, based on the current active power P and reactive power Q of the load, the current apparent power S of each transformer is calculated. SN Among them, the current apparent power S of each transformer SN The relationship between the active power P and reactive power Q of the current load is shown in formula (6):

[0177]

[0178] S702. Calculate the apparent power supplied based on the power supplied by each transformer and the reactive power loss of the corresponding AC / DC conversion unit of each transformer.

[0179] Specifically, based on the transfer power P of each transformer s And the reactive power loss Q of each transformer corresponding to the AC / DC conversion unit S Calculate the power supply of S in the power supply. S Among them, the apparent power S to be transferred is calculated. S The calculation can be performed according to formula (6), such as the apparent power of the power supply.

[0180] It should be noted that the apparent power supplied by each transformer can also be obtained directly from the data acquisition device. The data acquisition device can be a meter or a concentrator. There are no restrictions here, and those skilled in the art can choose according to the actual situation.

[0181] S703. Determine whether the sum of the current apparent power and the apparent power supplied by each transformer is greater than the preset operating capacity of each transformer. If it is less than or equal to the preset operating capacity of each transformer, proceed to step S704; if it is greater than the preset operating capacity of each transformer, proceed to step S705. The preset fine-tuning conditions can be set according to actual conditions.

[0182] S704. If the capacity is less than or equal to the preset operating capacity of each transformer, then each transformer is determined to meet the corresponding load demand.

[0183] S705. If the load exceeds the preset operating capacity of each transformer, then each transformer is determined to be not meeting the corresponding load demand.

[0184] Specifically, determine the current apparent power S of each transformer that needs to be supplied. SN and the apparent power S of the power transfer transformer S Does the sum of these values ​​exceed the preset operating capacity S of each power supply transformer? i If less than or equal to the preset operating capacity S of each power supply transformer.i If each supply transformer meets the corresponding supply load demand, then each supply transformer can supply the supply load demand to each transformer requiring supply. If the demand exceeds the preset operating capacity S of each supply transformer... i If it is determined that each transformer providing power transfer does not meet the corresponding power transfer load demand, then the flexible distribution area interconnection device will not meet the load transfer demand.

[0185] Continue to refer to Figure 5 If transformer substation #2 needs to transfer power to transformer substation #1, the current apparent power S of transformer #2... SN2 With the apparent power S to be transferred S2 The sum must be less than or equal to the maximum capacity S of transformer substation #2. max2 Or the safe operating capacity S2. That is, S SN2 +S S2 When S2 ≤ S2, it is determined that transformer area #2 meets the load transfer requirements of transformer area #1. At this time, the flexible transformer area interconnection device 400 can transfer the load of its transformer area to meet the load demand of the transformer area requiring transfer. If the load is greater than the preset operating capacity S of transformer #2, then... i S SN2 +S S2 When the value is greater than S2, it is determined that transformer #2 does not meet the power transfer requirements of transformer #1. At this time, the flexible transformer interconnection device 400 does not meet the load transfer requirements of the transformer area.

[0186] For example, if transformer substation #2 needs to transfer power to transformer substation #1, and the preset operating capacity S1 of transformer #1 is 50KVA, the preset operating capacity S2 of transformer #2 is 50KVA, and the current apparent power S of transformer #1 is... SN1 The current apparent power S of transformer #2 is 20KVA. SN2 The apparent power S of transformer #2 is 80 kVA. SN2 The apparent power S of transformer #2 is greater than its preset operating capacity S2. SN2 Subtracting its preset operating capacity S2 yields the apparent power S that transformer #2 needs to supply. S2 The current apparent power S of transformer #1 is 30KVA. SN1 With the apparent power S to be transferred S2 The sum must be less than or equal to the maximum capacity S of transformer substation #2. max2 Or the safe operating capacity S2, i.e., S SN1 +S S2If (20KVA + 30KVA) ≤ S²(50KVA), then transformer #2 meets the corresponding load transfer demand. Therefore, the apparent power S of transformer #2 can be calculated. S2 The 30KVA is supplied by transformer #1. Therefore, the current apparent power S of transformers #1 and #2 is... SN Both are 50KVA, achieving load balance between transformer substation #1 and transformer substation #2.

[0187] Conversely, the preset operating capacity S1 of transformer #1 is 50KVA, the preset operating capacity S2 of transformer #2 is 50KVA, and the current apparent power S of transformer #1 is... SN1 The current apparent power S of transformer #2 is 20KVA. SN2 The current apparent power S of transformer #1 is 90 kVA. SN2 When the apparent power S of transformer #1 is less than its preset operating capacity S2, the apparent power S of transformer #1 is... SN1 With the apparent power S to be transferred S2 The sum must be greater than the maximum capacity S of transformer substation #2. max2 Or the safe operating capacity S2, i.e., S SN1 +S S2 (20KVA+40KVA)>S2(50KVA) Therefore, it is determined that transformer #1 does not meet the corresponding load transfer demand. To alleviate the load pressure on the transformer #2 area, the transfer capacity S of transformer #1 can be considered as power. S1 The 30KVA is transferred to transformer #2, thus reducing the load on transformer #2 from 90KVA to 60KVA, resulting in an overload of 10KVA. The 10KVA overload can be reduced according to actual load demand.

[0188] In the above embodiments Figure 7 Based on this, the embodiments of this application also provide an example of a control method for a flexible transformer interconnection device for determining whether a preset fine-tuning condition for a preset change power value is met, which will be further described below with reference to the accompanying drawings. Figure 9 This is a schematic diagram illustrating the determination of whether the preset fine-tuning condition S603 for determining the preset change power value is met in a control method for another flexible transformer interconnection device provided in this application embodiment. Figure 9 As shown, the method may include the following steps:

[0189] S801. Calculate the load power change value of the target transformer based on the current load active power and the historical load active power.

[0190] S802. Calculate the power ratio of the load power change value and the rated power of the target AC / DC conversion unit.

[0191] S803. Determine whether the power ratio is less than the preset power ratio threshold. If the power ratio is less than the preset power ratio threshold, proceed to step 704. If the power ratio is greater than the preset power ratio threshold, proceed to step 705.

[0192] S804. If the power ratio is less than the preset power ratio threshold, then the preset fine-tuning condition of the preset power value is met.

[0193] S805. If the power ratio is greater than or equal to the preset power ratio threshold, then it is determined that the preset fine-tuning condition of the preset power value change is not met.

[0194] The preset power ratio threshold can be set according to the actual situation; for example, the preset power ratio threshold can be 5%.

[0195] Specifically, based on the current load active power P 当前 and historical load active power P 历史 Calculate the load power change ΔP of the target transformer. 负 That is, the change in load power ΔP 负 =P 当前 -P 历史 And calculate the load power change value ΔP. 负 The rated power P of the target AC / DC converter unit 额定 The power percentage PER, i.e., the power percentage Then it is determined whether the power ratio PER is less than the preset power ratio threshold. If the power ratio PER is less than the preset power ratio threshold, it is determined that the preset fine-tuning condition of the preset change power value ΔP is met; if the power ratio PER is greater than or equal to the preset power ratio threshold, it is determined that the preset fine-tuning condition of the preset change power value ΔP is not met.

[0196] For example, continuing to combine the above Figure 5 If the load of transformer #2 increases by 10kW of active power, the small power change value ΔP of the load power can be set to 10kW, the rated power of the flexible distribution interconnection device is 250kW, and the data can be sent to the flexible distribution interconnection device for small-range power adjustment.

[0197] When a small change in load power occurs in the flexible distribution transformer interconnection device, such as when the load power change value ΔP is different from the rated power P of the target AC / DC converter unit... 额定 When the power ratio PER is less than the preset power ratio threshold (e.g., preset power ratio threshold = 5%), it can be adjusted by the load power change value ΔP; when the load power change value ΔP is less than the rated power P of the target AC / DC converter unit... 额定 If the power ratio PER is greater than or equal to the preset power ratio threshold (e.g., preset power ratio threshold = 5%), then it is determined that the preset fine-tuning condition of the preset power value change is not met.

[0198] Right now If the preset fine-tuning condition for the preset change power value is not met, then at least two transformers will be re-acquired to obtain new transfer power P. 新 And the new safe operating capacity S of at least two transformers 新i Based on the new safe operating capacity S of at least two transformers 新i Determine the new droop coefficient K for at least two AC / DC conversion units respectively. P According to the new droop coefficient K corresponding to each AC / DC conversion unit P The preset DC voltage reference value and the new power supply P of the transformer corresponding to each AC / DC conversion unit. 新 Recalculate the new target DC voltage value U for each AC / DC converter unit. dc Based on the new target DC voltage value U of at least two AC / DC conversion units dc Control at least two AC / DC converter units respectively, so that the DC-side voltage values ​​of at least two AC / DC converter units reach the corresponding new target DC voltage value U. dc .

[0199] It should be noted that the above are embodiments of the control method for flexible transformer interconnection devices and should not be construed as limiting this application. Other examples, implementation methods, or embodiments can be selected based on this application, and no specific limitations are made here.

[0200] Figure 10 This is a schematic diagram of a load transfer method for a flexible transformer interconnection device provided in an embodiment of this application. Figure 10 As shown in the embodiments of this application, a load transfer method for a flexible transformer interconnection device may include the following steps:

[0201] S901. Perform power flow calculations on the planned closed-loop distribution network.

[0202] Specifically, power flow calculations are performed on the planned closed-loop distribution network in order to determine which transformer to transfer power to based on the voltage flow points in the planned closed-loop distribution network, so that the load of the transformer substations in the entire distribution network reaches a balanced state.

[0203] S902. Obtain the power to be transferred between transformer substations and the safe operating capacity S of the associated transformer substations. i .

[0204] Specifically, the power P to be transferred between transformer substations can be obtained from the power dispatching system or a preset power load prediction algorithm. s ; Safe operating capacity S of associated transformer substation i This is a fixed setting value.

[0205] S903, Calculate the sag coefficient K of the flexible transformer interconnection device. P Set the DC reference voltage value U ref .

[0206] S904, based on the power supply P s droop coefficient K P and DC reference voltage value U ref Using a preset droop control algorithm, the target DC voltage value U of each AC / DC converter unit is calculated. dc .

[0207] Specifically, the target DC voltage value U of each AC / DC converter unit is calculated. dc You can refer to the above formula (5)U dcs -U ref =-K P P s +ΔP.

[0208] S905, Real-time monitoring of the active power P of the transformer substation load. X and reactive power Q X Determine the power supply P s Does the active power P of the transformer substation area being transferred meet the requirements? X If yes, proceed to step S908; otherwise, proceed to step S906.

[0209] S906. Based on the active power P of the current load in the transformer substation where the target transformer is located. 当前 The active power P of the historical load of each transformer area 历史 The system determines whether the preset fine-tuning conditions for the preset power value are met. If met, step S907 is executed; otherwise, the system returns to step S902 to recalculate the target DC voltage value U for at least two AC / DC converter units. dc .

[0210] S907. Adjust the preset variable power value ΔP, and based on the adjusted preset variable power value ΔP, return to step S904 to recalculate the target DC voltage value U of at least two AC / DC conversion units. dc .

[0211] S908, power supply P s The active power P of the transformer substation load meets the requirements for power transfer. X If so, execution will end.

[0212] It should be noted that in the load transfer strategy steps of the above-mentioned flexible distribution transformer interconnection device, if the transformer area load being transferred has reactive power Q... XThe demand can be directly sent to the AC / DC conversion unit of the transformer substation connected to the flexible substation interconnection device to perform reactive power compensation for the transformer substation.

[0213] Continuing with the above Figure 5 The flexible transformer area interconnection device can achieve reactive power compensation through its internal AC / DC conversion unit, such as the reactive power Q of transformer #1 monitoring area. X When compensation is needed, the required reactive power compensation value Qc can be calculated and sent to AC / DC conversion unit 403-1# connected to the power grid under transformer #1 for reactive power compensation. Similarly, transformer #2 can perform reactive power compensation through its connected AC / DC conversion unit 403-2#, so as to ensure the stable operation of the power system.

[0214] As another concrete example, please refer to [link / reference]. Figure 5 A residential community's No. 1 transformer has a maximum capacity of 250kVA, while a nearby processing plant's No. 2 transformer has a maximum capacity of 500kVA. The safe operating power of both transformers is 80% of their maximum capacity. During the daytime hours of 10:00-18:00, the residential community's electricity consumption is less than 100kVA, while the processing plant's active power consumption reaches 500kW during the afternoon hours of 13:00-16:00. At this time, according to the power company's dispatch center plan, 100kW of active power will be transferred from the residential community's No. 1 transformer to the load line of the processing plant's No. 2 transformer. The operating active power of the processing plant's No. 2 transformer will then be 400kW.

[0215] The power supply company introduced a flexible distribution transformer interconnection device. In this device, the AC terminal of AC converter 401-1 is connected to the interconnection line of transformer No. 1 in the residential area, and the AC terminal of DC converter 401-2 is connected to the interconnection line of transformer No. 2 in the processing plant. The rated power of the flexible distribution transformer interconnection device is 250kW, and the voltage range of the DC terminal of DC converter 401 is between [700, 1000].

[0216] According to the description of the above embodiments, the maximum capacity of transformer No. 1 is 250kVA, and the maximum capacity of transformer No. 2 is 500kVA. The transformer operating coefficient K of the flexible distribution transformer interconnection device is then calculated according to formula (3). S :

[0217]

[0218] Among them, the preset high-frequency isolation unit conversion coefficient K C The reliability coefficient K is 0.5. T The value is 1. Then, the sag coefficient K of the flexible transformer interconnection device is calculated according to formula (2). P:

[0219] K P =K T *K C *K S =1 x 0.5 x 0.33 = 0.165

[0220] As described in the above embodiments, the power supply P s Assuming the initial load power change ΔP is 0kW and the load power is 100kW, with the DC terminal of AC / DC converter unit 401-2 as the reference point, the power supplied is P. s If the value is negative, the voltage difference between the DC terminals of AC / DC converter units 401-1 and 401-2 is calculated according to formula (5):

[0221] U dcs -U ref =-K P P s +ΔP=(-0.165)x(-100KW)+0KW=16.5V

[0222] Next, set the DC reference voltage value U at the DC terminal of the AC / DC conversion unit 401-2. ref It is 750V, and will transfer power P s droop coefficient K P and DC voltage reference value U ref Issued to the flexible distribution area interconnection device.

[0223] The preset voltage U at the DC terminal of the AC / DC converter unit 401-1 can be calculated according to formula (5). dcs :U dcs =-K P P s +ΔP+U ref =16.5V + 750V = 766.5V

[0224] In other words, the voltage value U at the DC terminal of the AC / DC conversion unit 401-1 dcs The DC reference voltage U at the DC terminal of the AC / DC converter unit 401-2 is greater than the DC reference voltage value. ref Then judge the process Figure 6 The DC outer loop control of the flexible transformer interconnection device transfers 100kW of transformer No. 1 to transformer No. 2 and monitors the load operation of transformer No. 2 in the processing plant in real time.

[0225] If the load of transformer No. 2 increases by 10kW of active power, the load power change value ΔP can be changed to 10kW. The rated power of the flexible distribution area interconnection device is 250kW, and the information is sent to the flexible distribution area interconnection device for small-scale power adjustment.

[0226] When the change in load power ΔP is different from the rated power P of the target AC / DC converter unit 额定 When the power ratio PER is less than the preset power ratio threshold (e.g., preset power ratio threshold = 5%), the preset fine-tuning condition for the preset power change value can be determined, that is, when a small power change occurs in the load power of the flexible transformer interconnection device, it can be adjusted by the load power change value ΔP; when the load power change value ΔP is less than the rated power P of the target AC / DC converter unit... 额定 If the power ratio PER is greater than or equal to the preset power ratio threshold (e.g., preset power ratio threshold = 5%), then it is determined that the preset fine-tuning condition of the preset power value change is not met.

[0227] Right now If the preset fine-tuning condition for the preset change power value is not met, then a new transfer power S from at least two transformers will be obtained. 新 And the new safe operating capacity S of at least two transformers 新i Based on the new safe operating capacity S of at least two transformers 新i Determine the new droop coefficient K for at least two AC / DC conversion units respectively. P According to the new droop coefficient K corresponding to each AC / DC conversion unit P The preset DC voltage reference value and the new power supply P of the transformer corresponding to each AC / DC conversion unit. 新 Recalculate the new target DC voltage value U for each AC / DC converter unit. dc Based on the new target DC voltage value U of at least two AC / DC conversion units dc Control at least two AC / DC converter units respectively, so that the voltage value at the DC terminal of at least two AC / DC converter units reaches the corresponding new target DC voltage value U. dc .

[0228] If the flexible distribution transformer interconnection device requires 50kvar of reactive power compensation, continue to refer to... Figure 5 When the reactive power Q of transformer No. 1 needs compensation, the required reactive power compensation value Q can be calculated. c The data is sent to transformer substation #1, and reactive power compensation is performed through AC / DC converter unit 403-1# connected to transformer substation #1. When reactive power Q of transformer substation #2 needs compensation, the required reactive power compensation value Q can be calculated. c The power is distributed to the No. 2 transformer substation and reactive power compensation is performed through the AC / DC conversion unit 403-2# connected to the No. 2 transformer substation. In other words, 20 kvar of reactive power can be compensated from the AC terminal of the AC / DC conversion unit 403-2# to the bus of the No. 2 transformer, thereby ensuring the stable operation of the power system.

[0229] It should be noted that the reactive power compensation value Q c The calculation can be performed by using the AC / DC conversion unit inside the flexible transformer interconnection device to compensate for reactive power on the bus of the corresponding transformer area.

[0230] In summary, the control method for a flexible distribution network interconnection device provided in this application obtains the transfer power and safe operating capacity of at least two transformers in the planned closed-loop distribution network, and determines the droop coefficients corresponding to at least two AC / DC conversion units. Based on the droop coefficient of each AC / DC conversion unit, a preset DC voltage reference value, and the transfer power of the transformer corresponding to each AC / DC conversion unit, the target DC voltage value of each AC / DC conversion unit is calculated. The method then controls at least two AC / DC conversion units to ensure that the DC terminal voltage values ​​of at least two AC / DC conversion units reach their respective target DC voltage values. Therefore, the control method of this application can achieve interconnection of at least two distribution networks, reduce the circulating current generated by closed-loop operation control in the distribution network, and adjust the load transfer power by adjusting relevant parameters in the DC droop mode based on real-time monitoring of load changes in the flexible distribution network, ensuring the stable operation of the distribution network and reducing the operating costs of the power system.

[0231] Based on the same inventive concept, this application also provides a flexible transformer interconnection device corresponding to the control method of the flexible transformer interconnection device. Since the principle of the device in this application is similar to the control method of the flexible transformer interconnection device described above in this application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be described again.

[0232] Figure 11 A schematic diagram of the control structure of a flexible transformer interconnection device provided in an embodiment of this application. The control device 30 of the flexible transformer interconnection device includes:

[0233] The acquisition module 31 is used to acquire the transfer power of at least two transformers in the power distribution network.

[0234] The calculation module 32 is used to determine the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit based on the conversion coefficient of each high-frequency isolation unit.

[0235] The control module 33 is used to control the DC voltage of the at least two AC / DC conversion units according to the droop coefficient of the at least two AC / DC conversion units.

[0236] According to one embodiment of this application, the calculation module 32 is specifically used for:

[0237] The droop coefficients of the two AC / DC conversion units are determined based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit.

[0238] According to one embodiment of this application, the calculation module 32 is specifically used for:

[0239] Based on the safe operating capacity of the two transformers, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units respectively;

[0240] Based on the transformer operating coefficients corresponding to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit, the droop coefficients of at least two AC / DC conversion units are determined respectively.

[0241] According to one embodiment of this application, the calculation module 32 is specifically used for:

[0242] Based on the safe operating capacity of each transformer and the sum of the safe operating capacities of the two transformers, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units.

[0243] According to one embodiment of this application, the control module 33 is specifically used for:

[0244] The target DC voltage value for each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter.

[0245] Based on the voltage values ​​at the DC terminals of at least two AC / DC conversion units, control is applied to at least two AC / DC conversion units respectively, so that the voltage values ​​at the DC terminals of at least two AC / DC conversion units respectively reach the corresponding target DC voltage values.

[0246] According to one embodiment of this application, the control unit 33 is further configured to:

[0247] The initial DC voltage value of each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter.

[0248] The target DC voltage value of each AC / DC converter is calculated based on the initial DC voltage value of each AC / DC converter and the detected voltage at the DC terminal of each AC / DC converter.

[0249] According to one embodiment of this application, the control unit 33 is further configured to:

[0250] The target DC voltage value for each AC / DC converter is calculated based on the droop coefficient of each AC / DC converter, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC converter, and the preset variable power value.

[0251] According to one embodiment of this application, the control unit 33 is further configured to:

[0252] Obtain the active and reactive power of the current load in the distribution area where each transformer is located;

[0253] Based on the current active power, reactive power and the transfer power of each transformer, determine whether each transformer meets the corresponding load demand.

[0254] If the target transformer does not meet the corresponding load demand, determine whether the preset fine-tuning conditions for the preset change power value are met based on the current active power of the load in the transformer area where the target transformer is located and the historical active power of the load in the transformer area where each transformer is located.

[0255] If the preset fine-tuning conditions for the preset variable power value are met, the preset variable power value is adjusted to obtain a new preset variable power value.

[0256] Based on the droop coefficient corresponding to each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the new preset variable power value, the target DC voltage value of each AC / DC conversion unit is recalculated.

[0257] Based on the recalculated DC terminal voltage values ​​of at least two AC / DC conversion units, control is applied to at least two AC / DC conversion units respectively, so that the DC terminal voltage values ​​of at least two AC / DC conversion units reach the corresponding target DC voltage values.

[0258] According to one embodiment of this application, the control unit 33 is used to determine whether each transformer meets the corresponding load demand based on the current load's active power, reactive power, and the transfer power of each transformer. Specifically, it is used for:

[0259] Calculate the current apparent power of each transformer based on the current active and reactive power of the load.

[0260] Calculate the apparent power supplied based on the power supplied by each transformer and the reactive power loss of the corresponding AC / DC conversion unit of each transformer.

[0261] Determine whether the sum of the current apparent power and the apparent power transferred to the power source of each transformer is greater than the preset operating capacity of each transformer.

[0262] If the capacity is less than or equal to the preset operating capacity of each transformer, then each transformer is determined to meet the corresponding load demand.

[0263] If the load exceeds the preset operating capacity of each transformer, then each transformer is determined to be not meeting the corresponding load demand.

[0264] According to one embodiment of this application, the control unit 33 is used to determine whether the preset fine-tuning conditions for the preset power change value are met based on the current active power of the target transformer area and the historical active power of the transformer area. Specifically, it is used for:

[0265] Calculate the power change value of the target transformer load based on the current active power and historical active power of the load.

[0266] Calculate the power change value of the load and the power ratio of the rated power of the target AC / DC converter unit;

[0267] If the power ratio is less than the preset power ratio threshold, then the preset fine-tuning condition of the preset power value change is met.

[0268] If the power ratio is greater than or equal to the preset power ratio threshold, then the preset fine-tuning condition for the preset power value change is not met.

[0269] According to one embodiment of this application, the control unit 33 is further configured to:

[0270] If the preset fine-tuning conditions for the preset change power value are not met, then the new preset transfer power of at least two transformers and the new safe operating capacity of at least two transformers will be obtained again.

[0271] Based on the new safe operating capacity of at least two transformers, determine the new droop coefficients for at least two AC / DC conversion units respectively;

[0272] Based on the new droop coefficient corresponding to each AC / DC conversion unit, the preset DC voltage reference value, and the new power supply of the transformer corresponding to each AC / DC conversion unit, the new target DC voltage value of each AC / DC conversion unit is recalculated.

[0273] Based on the new target DC voltage values ​​of at least two AC / DC conversion units, control is applied to at least two AC / DC conversion units respectively, so that the voltage values ​​at the DC terminals of at least two AC / DC conversion units reach the corresponding new target DC voltage values.

[0274] It should be noted that for details not disclosed in the flexible transformer interconnection device of this application embodiment, please refer to the details disclosed in the control method of the flexible transformer interconnection device of this application embodiment, which will not be repeated here.

[0275] These modules can be one or more integrated circuits configured to implement the above methods, such as one or more Application Specific Integrated Circuits (ASICs), one or more microprocessors, or one or more Field Programmable Gate Arrays (FPGAs). Alternatively, when a module is implemented using processing element scheduler code, the processing element can be a general-purpose processor, such as a Central Processing Unit (CPU) or other processor capable of calling program code. Furthermore, these modules can be integrated together as a system-on-a-chip (SOC).

[0276] Figure 12 This is a schematic diagram of the structure of a control device for a flexible interconnection device provided in an embodiment of this application. The control device 1100 can be integrated into a terminal device or a chip of a terminal device. The terminal can be a computing device with data processing capabilities.

[0277] The control device includes: processor 1101 and memory 1102.

[0278] The memory 1102 is used to store programs, and the processor 1101 calls the programs stored in the memory 1102 to execute the above method embodiments. The specific implementation and technical effects are similar, and will not be described again here.

[0279] Optionally, embodiments of this application also provide a computer-readable storage medium storing a computer program. When the computer program is run by a processor, the processor executes the steps of the control method for the flexible interconnection device in the above embodiments. The specific implementation and technical effects are similar and will not be repeated here.

[0280] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0281] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0282] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or in a combination of hardware and software functional units.

[0283] The integrated units implemented as software functional units described above can be stored in a computer-readable storage medium. These software functional units, stored in a storage medium, include several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) or processor to execute some steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0284] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for a flexible transformer interconnection device, characterized in that: A control unit is applied in the flexible distribution transformer interconnection device, the flexible distribution transformer interconnection device including at least one high-frequency isolation unit, a control unit, and at least two AC / DC conversion units; wherein, the AC terminals of the at least two AC / DC conversion units are respectively connected to at least two transformers in the power distribution network, and each high-frequency isolation unit is used to perform high-frequency isolation on the DC signals of the AC / DC conversion units connected to the two transformers; the method includes: Obtain the transfer power from at least two transformers in the power distribution network; Based on the conversion coefficient of each high-frequency isolation unit, determine the droop coefficient of the two AC / DC conversion units associated with each high-frequency isolation unit; Based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC conversion unit, the target DC voltage value of each AC / DC conversion unit is calculated; based on the voltage values ​​of the DC terminals of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the voltage values ​​of the DC terminals of the at least two AC / DC conversion units reach the corresponding target DC voltage values.

2. The control method for the flexible transformer interconnection device according to claim 1, characterized in that, The step of determining the droop coefficient of the two AC / DC converters associated with each high-frequency isolation unit based on the conversion coefficient of each high-frequency isolation unit includes: The droop coefficient of the two AC / DC conversion units is determined based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit.

3. The control method for the flexible transformer interconnection device according to claim 2, characterized in that, The step of determining the droop coefficient of the two AC / DC conversion units based on the safe operating capacity of the two transformers connected to the two AC / DC conversion units and the conversion coefficient of each high-frequency isolation unit includes: Based on the safe operating capacity of the two transformers, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units respectively; The droop coefficients of the at least two AC / DC conversion units are determined based on the transformer operating coefficients corresponding to the two AC / DC conversion units and the conversion coefficients of each high-frequency isolation unit.

4. The control method for the flexible transformer interconnection device according to claim 3, characterized in that, The calculation of the transformer operating coefficients corresponding to the two AC / DC conversion units based on the safe operating capacity of the two transformers includes: Based on the safe operating capacity of the two transformers and the sum of their safe operating capacities, calculate the transformer operating coefficients corresponding to the two AC / DC conversion units.

5. The control method for the flexible transformer interconnection device according to claim 1, characterized in that, The step of calculating the target DC voltage value for each AC / DC converter based on the droop coefficient of each AC / DC converter, a preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter includes: The initial DC voltage value of each AC / DC conversion unit is calculated based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC conversion unit. The target DC voltage value of each AC / DC converter is calculated based on the initial DC voltage value of each AC / DC converter and the detected voltage at the DC terminal of each AC / DC converter.

6. The control method for the flexible transformer interconnection device according to claim 5, characterized in that, The step of calculating the target DC voltage value for each AC / DC converter based on the droop coefficient of each AC / DC converter, a preset DC voltage reference value, and the power supply of the transformer corresponding to each AC / DC converter includes: The target DC voltage value of each AC / DC conversion unit is calculated based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the preset variable power value.

7. The control method for the flexible transformer interconnection device according to claim 6, characterized in that, The method further includes: Obtain the active and reactive power of the current load in the distribution area where each transformer is located; Based on the active power of the current load, the reactive power, and the transfer power of each transformer, determine whether each transformer meets the corresponding load demand; If the target transformer does not meet the corresponding load demand, it is determined whether the preset fine-tuning condition of the preset change power value is met based on the active power of the current load of the transformer area where the target transformer is located and the active power of the historical load of the transformer area where each transformer is located. If the preset fine-tuning conditions of the preset variable power value are met, the preset variable power value is adjusted to obtain a new preset variable power value. Based on the droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, the power supplied by the transformer corresponding to each AC / DC conversion unit, and the new preset variable power value, the target DC voltage value of each AC / DC conversion unit is recalculated. Based on the recalculated DC terminal voltage values ​​of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the DC terminal voltage values ​​of the at least two AC / DC conversion units reach the corresponding target DC voltage values.

8. The control method for the flexible transformer interconnection device according to claim 7, characterized in that, The step of determining whether each transformer meets the corresponding load demand based on the active power of the current load, the reactive power, and the transfer power of each transformer includes: Calculate the current apparent power of each transformer based on the active power and reactive power of the current load; The apparent power supplied is calculated based on the power supplied by each transformer and the reactive power loss of the AC-DC conversion unit corresponding to each transformer. Determine whether the sum of the current apparent power of each transformer and the apparent power of the transfer is greater than the preset operating capacity of each transformer; If the value is less than or equal to the preset operating capacity of each transformer, then each transformer is determined to meet the corresponding load requirement. If the load exceeds the preset operating capacity of each transformer, then each transformer is determined to not meet the corresponding load requirement.

9. The control method for the flexible transformer interconnection device according to claim 7, characterized in that, The step of determining whether the preset fine-tuning condition for the preset change power value is met based on the current active power of the target transformer area and the historical active power of the transformer area includes: Calculate the power change value of the target transformer load based on the active power of the current load and the active power of the historical load; Calculate the power change value of the load and the power ratio of the rated power of the target AC / DC converter unit; If the power ratio is less than the preset power ratio threshold, then the preset fine-tuning condition of the preset power value is met. If the power ratio is greater than or equal to the preset power ratio threshold, then it is determined that the preset fine-tuning condition of the preset change power value is not met.

10. The control method for the flexible transformer interconnection device according to claim 7, characterized in that, The method further includes: If the preset fine-tuning conditions for the preset change power value are not met, then the new preset transfer power of the at least two transformers and the new safe operating capacity of the at least two transformers are re-acquired. Based on the new safe operating capacity of the at least two transformers and the conversion coefficient of the at least one high-frequency isolation unit, determine the new droop coefficients of the at least two AC-DC conversion units respectively. Based on the new droop coefficient of each AC / DC conversion unit, the preset DC voltage reference value, and the new power supply of the transformer corresponding to each AC / DC conversion unit, the new target DC voltage value of each AC / DC conversion unit is recalculated. Based on the new target DC voltage values ​​of the at least two AC / DC conversion units, the at least two AC / DC conversion units are controlled respectively, so that the voltage values ​​of the DC terminals of the at least two AC / DC conversion units reach the corresponding new target DC voltage values.

11. A flexible transformer substation interconnection device, characterized in that, include: It includes at least two AC / DC conversion units, at least one high-frequency isolation unit, and a control unit; The AC terminals of the at least two AC / DC conversion units are respectively connected to at least two transformers in the power distribution network, and the DC terminals of two adjacent AC / DC conversion units are respectively connected to the two ends of a high-frequency isolation unit. The control unit is used to execute the control method of the flexible interconnection device according to any one of claims 1-10.

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