Distributed energy storage system

Abstract

The invention provides a distributed energy storage system, and relates to the technical field of energy storage. The distributed energy storage system comprises a first power conversion device, a second power conversion device and a control device, the alternating-current end of the first power conversion device is connected with a transformer of a preset transformer area, the direct-current end of the first power conversion device is connected with the first direct-current end of the second power conversion device, and the second direct-current end of the first power conversion device is used for being connected with the energy storage device; the control device is connected with the first power conversion device and the second power conversion device. The control device is used for obtaining a three-phase AC voltage parameter of the AC end of the first power conversion device; determining a first control parameter of the first power conversion device according to the three-phase AC voltage parameter; acquiring a detection DC voltage parameter of a first DC end of the second power conversion device; and determining a second control parameter of the second power conversion device according to the detected DC voltage parameter. Therefore, the power distribution efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a distributed energy storage system. Background Art

[0002] In the process of distribution network construction, due to the low construction standards and insufficient investment capacity, the distribution network structure is weak and the voltage regulation capacity is insufficient. Especially in the county and village level where the power supply radius is large, it is difficult to adapt to the characteristics of rapid growth in load demand, large seasonal load fluctuations, dispersed users, and widespread access to distributed energy. Overvoltage and low voltage of distribution lines still exist and appear dynamically. In order to optimize the power supply quality, distributed energy storage solutions have been widely proposed in the power supply quality management of the substation area.

[0003] Currently, the main single-stage distributed energy storage solution is that it needs to be based on standard battery cells in the industrial chain. In order to achieve a certain voltage, it requires relatively large power and capacity. It also has high requirements for the converter and the DC battery voltage, which leads to increased costs and low distribution efficiency. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies in the above-mentioned prior art and provide a distributed energy storage system to solve the problems of low power distribution efficiency in the prior art.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] In a first aspect, an embodiment of the present application provides a distributed energy storage system, the distributed energy storage system comprising: a first power conversion device, a second power conversion device, and a control device;

[0007] The AC end of the first power conversion device is connected to a transformer in a preset station area, the DC end of the first power conversion device is connected to a first DC end of the second power conversion device, and the second DC end of the first power conversion device is used to connect to an energy storage device;

[0008] The control device is connected to the first power conversion device and the second power conversion device respectively;

[0009] The control device is used to:

[0010] Acquiring three-phase AC voltage parameters of the AC end of the first power conversion device;

[0011] Determining a first control parameter of the first power conversion device according to the three-phase AC voltage parameter to control a DC operating voltage at a DC end of the first power conversion device;

[0012] Acquiring a detected DC voltage parameter of the first DC terminal of the second power conversion device;

[0013] A second control parameter of the second power conversion device is determined according to the detected DC voltage parameter to control the operating power of the second power conversion device.

[0014] Optionally, the control device includes: a first control unit and a second control unit, wherein the first control unit and the second control unit are respectively connected to the first power conversion device and the second power conversion device to control the first power conversion device and the second power conversion device respectively.

[0015] Optionally, the distributed energy storage system further includes: an energy storage device, a fire protection device, and a thermal management device;

[0016] The second control unit is respectively connected to the energy storage device, the fire fighting device, and the thermal management device;

[0017] The second DC end of the second power conversion device is connected to the DC end of the energy storage device.

[0018] Optionally, the control device is specifically used for:

[0019] Calculating an average AC voltage parameter according to the three-phase AC voltage parameter;

[0020] According to the average AC voltage parameter, an expected DC voltage parameter of the first power conversion device is calculated, and the first control parameter includes: the expected DC voltage parameter.

[0021] Optionally, the control device is specifically used for:

[0022] Calculating an AC voltage deviation parameter of the first power conversion device according to the average AC voltage parameter and a preset AC voltage rated parameter of the first power conversion device;

[0023] The expected DC voltage parameter is calculated according to the AC voltage deviation parameter, a preset AC-DC conversion step size of the first power conversion device, and a preset DC voltage rated parameter of the first power conversion device.

[0024] Optionally, the control device is specifically used for:

[0025] Calculating three-phase AC voltage deviation parameters of the first power conversion device respectively according to the average AC voltage parameter and the three-phase AC voltage parameter;

[0026] According to the three-phase AC voltage deviation parameter, the three-phase real-time operating power of the first power conversion device, and the preset AC voltage power adjustment step, the three-phase expected power parameters of the first power conversion device are calculated respectively, and the first control parameter also includes: the three-phase expected power parameters.

[0027] Optionally, the control device is specifically used for:

[0028] The expected DC voltage parameter is limited according to a preset DC voltage limit range of the first power conversion device.

[0029] Optionally, the control device is specifically used for:

[0030] According to the detected DC voltage parameter and the real-time operating power parameter of the second power conversion device, the expected compensation power parameter of the second power conversion device is calculated, and the second control parameter includes: the expected compensation power parameter.

[0031] Optionally, the control device is specifically used for:

[0032] Calculating a lower limit compensation power parameter of the second power conversion device according to the lower limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operating power parameter, and a preset voltage power adjustment step of the second power conversion device;

[0033] Calculating an upper limit compensation power parameter of the second power conversion device according to the upper limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operating power parameter, and the preset voltage power adjustment step;

[0034] The expected compensation power parameter is calculated according to the lower limit compensation power parameter and the upper limit compensation power parameter.

[0035] Optionally, the control device is specifically used for:

[0036] Determining a rated lower limit compensation power parameter and a rated upper limit compensation power parameter of the second power conversion device respectively according to a rated operating power parameter of the second power conversion device;

[0037] According to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter, respectively, the lower limit compensation power parameter and the upper limit compensation power parameter are subjected to amplitude limiting processing;

[0038] Calculate the total compensation power parameter according to the lower compensation power parameter and the upper compensation power parameter after the limiting process;

[0039] The total compensation power parameter is limited according to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter to obtain the expected compensation power parameter.

[0040] Compared with the prior art, this application has the following beneficial effects:

[0041] The present application provides a distributed energy storage system, which includes: a first power conversion device, a second power conversion device and a control device; the AC end of the first power conversion device is connected to the transformer of the preset substation, the DC end of the first power conversion device is connected to the first DC end of the second power conversion device, and the second DC end of the first power conversion device is used to connect the energy storage device; the control device is connected to the first power conversion device and the second power conversion device respectively; the control device is used to: obtain the three-phase AC voltage parameters of the AC end of the first power conversion device; determine the first control parameters of the first power conversion device according to the three-phase AC voltage parameters to control the DC operating voltage of the DC end of the first power conversion device; obtain the detected DC voltage parameters of the first DC end of the second power conversion device; determine the second control parameters of the second power conversion device according to the detected DC voltage parameters to control the operating power of the second power conversion device. Thus, by controlling the first power conversion device and the second power conversion device, voltage stability and power stability are achieved, which can not only meet the requirement of stabilizing the voltage within the power supply requirement range, but also effectively reduce the power and capacity of the DC side of the energy storage system, and can be applied to small-capacity batteries, expand the scope of use of the energy storage system, reduce the power distribution cost, and improve the power distribution efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 A schematic diagram of a distributed energy storage system provided for this application;

[0044] Figure 2 It is a flow chart of a method for controlling voltage in a substation;

[0045] Figure 3 A schematic diagram of the structure of another distributed energy storage system provided in an embodiment of the present application;

[0046] Figure 4 A schematic diagram of the structure of another distributed energy storage system provided in an embodiment of the present application;

[0047] Figure 5 A schematic flow chart of a method for determining a first control parameter of a first power conversion device provided in an embodiment of the present application;

[0048] Figure 6 A flowchart of a method for calculating a desired DC voltage parameter of a first power conversion device provided in an embodiment of the present application;

[0049] Figure 7 A schematic flow chart of a method for calculating three-phase expected power parameters of a first power conversion device provided in an embodiment of the present application;

[0050] Figure 8 A schematic diagram of adjusting a DC voltage according to an AC voltage provided in an embodiment of the present application;

[0051] Fig. 9 A flowchart of a method for calculating a desired compensation power parameter of a second power conversion device provided in an embodiment of the present application;

[0052] Fig.10 A flowchart of another method for calculating a desired compensation power parameter of a second power conversion device provided in an embodiment of the present application;

[0053] Fig.11 A schematic diagram of adjusting the expected compensation power of the second power conversion device according to the DC voltage value provided in an embodiment of the present application.

[0054] Icons: 1-first power conversion device, 2-second power conversion device, 3-control device, 31-first control unit, 32-second control unit, 4-energy storage device, 5-fire fighting device, 6-thermal management device. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0057] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0058] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0059] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0060] A distributed energy storage system provided in this application is explained below through a specific example. Figure 1 A schematic diagram of a distributed energy storage system provided in this application. Figure 1 As shown, the distributed energy storage system includes: a first power conversion device 1, a second power conversion device 2 and a control device 3.

[0061] The AC end of the first power conversion device 1 is connected to the transformer of the preset station area, the DC end of the first power conversion device 1 is connected to the first DC end of the second power conversion device 2, and the second DC end of the first power conversion device 1 is used to connect the energy storage device.

[0062] The control device 3 is connected to the energy storage systems of the first power conversion device 1 and the second power conversion device 2 respectively.

[0063] For example, the transformer is also connected to a preset power grid, the first power conversion device 1 and the second power conversion device 2 are PCS (power conversion system), the first power conversion device 1 is a converter for converting AC to DC, and the second power conversion device 2 is a converter for converting DC to DC. The first power conversion device 1 and the second power conversion device 2 form a two-stage architecture.

[0064] The transformer transmits electric energy to the energy storage device through the first power conversion device 1 and the second power conversion device 2. The control device 3 controls the first power conversion device 1 and the second power conversion device 2 respectively to achieve the function of stabilizing the transmission of the grid voltage.

[0065] For example, the power conversion device includes a switch unit. The control device 3 is respectively connected to the switch units in the power conversion device, and controls the power conversion device by controlling the switch units. Specifically, the AC end of the first power conversion device 1 includes an AC switch, the DC end of the first power conversion device 1 includes a DC switch, and the DC end of the second power conversion device 2 includes a DC switch.

[0066] Specifically, the control device 3 is used to execute a station voltage control method. Figure 2FIG. 1 is a flow chart of a method for controlling the voltage in a substation. Figure 2 As shown, the method includes:

[0067] S101. Acquire three-phase AC voltage parameters of an AC terminal of a first power conversion device.

[0068] The AC end of the first power conversion device obtains the voltage of the preset power grid through the transformer of the preset station area. The voltage value of the AC end of the first power conversion device is the same as the voltage value transmitted by the preset power grid. By detecting the three-phase AC voltage of the AC end of the first power conversion device, the three-phase AC voltage of the preset power grid can be obtained.

[0069] S102: Determine a first control parameter of the first power conversion device according to the three-phase AC voltage parameter to control a DC operating voltage at a DC end of the first power conversion device.

[0070] The three-phase AC voltage parameters characterize the grid voltage. The DC operating voltage at the DC end of the first power conversion device is adjusted and controlled according to the grid voltage so that the first power conversion device is always in a DC constant voltage mode, thereby stabilizing the DC voltage.

[0071] S103: Acquire a detected DC voltage parameter of a first DC terminal of a second power conversion device.

[0072] The first DC terminal of the second power conversion device is connected to the DC terminal of the first power conversion device. In theory, the detected DC voltage parameter of the first DC terminal of the second power conversion device is the same as the DC operating voltage of the DC terminal of the first power conversion device. That is, by obtaining the detected DC voltage parameter of the first DC terminal, the DC operating voltage of the DC terminal after control adjustment is obtained.

[0073] That is to say, the detected DC voltage parameter is the DC voltage after being stabilized.

[0074] S104: Determine a second control parameter of the second power conversion device according to the detected DC voltage parameter to control the operating power of the second power conversion device.

[0075] According to the detected DC voltage parameter after voltage stabilization, the operating power of the second power conversion device is controlled. Since the first power conversion device is in the DC constant voltage mode after the above control, the voltage and operating power of the second DC terminal of the second power conversion device are both in a stable state by controlling the operating power of the second power conversion device.

[0076] Therefore, by controlling the first power conversion device and the second power conversion device, voltage stability and power stability can be achieved, which can not only meet the requirement of stabilizing the voltage within the power supply requirement range, but also effectively reduce the power and capacity of the DC side of the energy storage system. It can be suitable for small-capacity batteries, expand the scope of use of the energy storage system, reduce the distribution cost, and improve the distribution efficiency.

[0077] In summary, in this embodiment, the distributed energy storage system includes: a first power conversion device, a second power conversion device and a control device; the AC end of the first power conversion device is connected to the transformer of the preset substation, the DC end of the first power conversion device is connected to the first DC end of the second power conversion device, and the second DC end of the first power conversion device is used to connect the energy storage device; the control device is connected to the first power conversion device and the second power conversion device respectively; the control device is used to: obtain the three-phase AC voltage parameter of the AC end of the first power conversion device; determine the first control parameter of the first power conversion device according to the three-phase AC voltage parameter to control the DC operating voltage of the DC end of the first power conversion device; obtain the detected DC voltage parameter of the first DC end of the second power conversion device; determine the second control parameter of the second power conversion device according to the detected DC voltage parameter to control the operating power of the second power conversion device. Thus, by controlling the first power conversion device and the second power conversion device, voltage stability and power stability are achieved, which can not only meet the requirement of stabilizing the voltage within the power supply requirement range, but also effectively reduce the power and capacity of the DC side of the energy storage system, and can be applied to small-capacity batteries, expand the scope of use of the energy storage system, reduce the power distribution cost, and improve the power distribution efficiency.

[0078] In the above Figure 1 Based on the corresponding embodiments, the embodiments of the present application also provide another distributed energy storage system. Figure 3 A schematic diagram of the structure of another distributed energy storage system provided in an embodiment of the present application.

[0079] like Figure 3 As shown, the control device 3 includes: a first control unit 31 and a second control unit 32, the first control unit 31 and the second control unit 32 are respectively connected to the first power conversion device 1 and the second power conversion device 2 to control the first power conversion device 1 and the second power conversion device 2 respectively.

[0080] For example, in addition to the control device 3 as a whole in the above embodiment, the control function of the control device 3 can also be implemented by using a first control unit 31 and a second control unit 32. The first control unit 31 controls the first power conversion device 1 and executes the method steps for controlling the first power conversion device 1. The second control unit 32 controls the second power conversion device 2 and executes the method steps for controlling the second power conversion device 2. The first control unit 31 is connected to the second control unit 32 for transmitting control information. By setting two control units, the control efficiency is improved.

[0081] In summary, in this embodiment, the control device includes: a first control unit and a second control unit, and the first control unit and the second control unit are respectively connected to the first power conversion device and the second power conversion device to control the first power conversion device and the second power conversion device respectively. Thus, by setting two control units, the control efficiency is improved.

[0082] In the above Figure 3 Based on the corresponding embodiments, the embodiments of the present application also provide another distributed energy storage system. Figure 4 A schematic diagram of the structure of another distributed energy storage system provided in an embodiment of the present application.

[0083] like Figure 4 As shown, the distributed energy storage system also includes: an energy storage device 4, a fire protection device 5, and a thermal management device 6.

[0084] The second control unit is respectively connected to the energy storage device, the fire protection device, and the thermal management device.

[0085] The second DC end of the second power conversion device is connected to the DC end of the energy storage device.

[0086] The second control unit can obtain the status of the energy storage device, the fire-fighting device, and the thermal management device, and can also control the energy storage device, the fire-fighting device, and the thermal management device.

[0087] For example, the energy storage device includes: a battery pack and a battery management system. The second DC terminal of the second power conversion device is connected to the DC terminal of the battery pack, the second control unit is connected to the battery management system, and the battery pack is connected to the battery management system. The second power conversion device can charge the battery pack first, and the battery pack can also discharge to the second power conversion device.

[0088] In summary, in this embodiment, the distributed energy storage system further includes: an energy storage device, a fire fighting device, and a thermal management device; the second control unit is connected to the energy storage device, the fire fighting device, and the thermal management device respectively; and the second DC end of the second power conversion device is connected to the DC end of the energy storage device. Thus, the use function of the distributed energy storage system is expanded.

[0089] In the above Figure 2 On the basis of the corresponding embodiment, the embodiment of the present application further provides a method for determining a first control parameter of a first power conversion device. Figure 5 A schematic flow chart of a method for determining a first control parameter of a first power conversion device provided in an embodiment of the present application.

[0090] like Figure 5 As shown, the control device is specifically used to determine the first control parameter of the first power conversion device according to the three-phase AC voltage parameter in S102, including:

[0091] S201. Calculate average AC voltage parameters according to three-phase AC voltage parameters.

[0092] For example, the calculation formula of the average AC voltage parameter is shown in the following formula (1):

[0093]

[0094] Among them, Uac_ave_pcs1 is the average AC voltage parameter, Uac_X_pcs1 is the effective value of each phase AC voltage, and X=a, b, c.

[0095] S202. Calculate an expected DC voltage parameter of the first power conversion device according to the average AC voltage parameter. The first control parameter includes: the expected DC voltage parameter.

[0096] By calculating the average AC voltage parameter, the constant voltage calculation of the AC voltage has been realized. The expected DC voltage parameter of the first power conversion device is calculated by the average AC voltage parameter, so that the first power conversion device is always in the DC constant voltage mode, which plays a role in stabilizing the DC voltage.

[0097] In summary, in this embodiment, the control device is specifically used to: calculate the average AC voltage parameter according to the three-phase AC voltage parameter; calculate the expected DC voltage parameter of the first power conversion device according to the average AC voltage parameter, and the first control parameter includes: the expected DC voltage parameter. Thus, the first power conversion device is always in the DC constant voltage mode, which plays a role in stabilizing the DC voltage.

[0098] In the above Figure 5 On the basis of the corresponding embodiments, the embodiments of the present application further provide a method for calculating expected DC voltage parameters of a first power conversion device. Figure 6 A schematic flow chart of a method for calculating expected DC voltage parameters of a first power conversion device provided in an embodiment of the present application.

[0099] like Figure 6As shown, the control device is specifically used to calculate the expected DC voltage parameter of the first power conversion device according to the average AC voltage parameter in S202, including:

[0100] S301 : Calculate an AC voltage deviation parameter of a first power conversion device according to an average AC voltage parameter and a preset AC voltage rated parameter of the first power conversion device.

[0101] For example, the calculation formula of the AC voltage deviation parameter of the first power conversion device is shown in the following formula (2):

[0102] ΔUac_pcs1=Uac_ave_pcs1-Uac_rate_pcs1 (2)

[0103] Wherein, ΔUac_pcs1 is an AC voltage deviation parameter of the first power conversion device, and Uac_rate_pcs1 is a preset AC voltage rated parameter.

[0104] S302: Calculate an expected DC voltage parameter according to an AC voltage deviation parameter, a preset AC / DC conversion step size of the first power conversion device, and a preset DC voltage rated parameter of the first power conversion device.

[0105] For example, the calculation formula of the expected DC voltage parameter is shown in the following formula (3):

[0106] Udc_ref_pcs1=Udc_rate_pcs1+ΔUac_pcs1×Uac_step2_pcs1 (3)

[0107] Among them, Udc_rate_pcs1 is the rated value of DC voltage, and Uac_step2_pcs1 is the adjustment step size of converting AC voltage to DC voltage.

[0108] Therefore, by taking the DC voltage rated value as a fixed value and gradually controlling the adjustment by adjusting the AC voltage to the DC voltage adjustment step, accurate calculation of the desired DC voltage parameters is achieved.

[0109] In summary, in this embodiment, the control device is specifically used to: calculate the AC voltage deviation parameter of the first power conversion device according to the average AC voltage parameter and the preset AC voltage rated parameter of the first power conversion device; calculate the expected DC voltage parameter according to the AC voltage deviation parameter, the preset AC-DC conversion step of the first power conversion device, and the preset DC voltage rated parameter of the first power conversion device. Thus, by taking the DC voltage rated value as a fixed value and gradually controlling and adjusting the AC voltage conversion DC voltage adjustment step, the expected DC voltage parameter can be accurately calculated.

[0110] In the above Figure 5On the basis of the corresponding embodiments, the embodiments of the present application further provide a method for calculating the three-phase expected power parameters of the first power conversion device. Figure 7 A flowchart of a method for calculating three-phase expected power parameters of a first power conversion device provided in an embodiment of the present application.

[0111] like Figure 7 As shown, the control device is specifically used to determine the first control parameter of the first power conversion device according to the three-phase AC voltage parameter in S102, and also includes:

[0112] S401 . Calculate three-phase AC voltage deviation parameters of a first power conversion device according to an average AC voltage parameter and a three-phase AC voltage parameter.

[0113] For example, the calculation formula of the three-phase AC voltage deviation parameter of the first power conversion device is shown in the following formula (4):

[0114] ΔUac_X_pcs1=(Uac_ave_pcs1-Uac_X_pcs1) (4)

[0115] Wherein, ΔUac_X_pcs1 is a three-phase AC voltage deviation parameter of the first power conversion device, Uac_X_pcs1 is a three-phase AC voltage parameter, and X=a, b, c.

[0116] S402. Calculate the three-phase expected power parameters of the first power conversion device according to the three-phase AC voltage deviation parameter, the three-phase real-time operating power of the first power conversion device, and the preset AC voltage power adjustment step. The first control parameter also includes: the three-phase expected power parameter.

[0117] For example, the calculation formula of the three-phase expected power parameter of the first power conversion device is shown in the following formula (5):

[0118] Pset_X_pcs1=ΔUac_X_pcs1×Uac_step1+Prun_X_pcs1 (5)

[0119] Among them, Pset_X_pcs1 is the expected power parameter of each phase of the first power conversion device, Prun_X_pcs1 is the real-time operating power of each phase of the first power conversion device, Uac_step1_pcs1 is the preset AC voltage power adjustment step, and X=a, b, c.

[0120] By controlling the desired power parameters of each phase of the first power conversion device, the voltage stability of each phase is controlled. After the voltage of each phase is stabilized, the DC operating voltage at the DC end of the first power conversion device is made more stable.

[0121] In summary, in this embodiment, the control device is specifically used to: calculate the three-phase AC voltage deviation parameters of the first power conversion device according to the average AC voltage parameters and the three-phase AC voltage parameters; calculate the three-phase expected power parameters of the first power conversion device according to the three-phase AC voltage deviation parameters, the three-phase real-time operating power of the first power conversion device, and the preset AC voltage power adjustment step, and the first control parameter also includes: the three-phase expected power parameters. Thereby, the voltages of each phase of the first power conversion device are stabilized, and the DC operating voltage of the DC end of the first power conversion device is indirectly stabilized.

[0122] Further, in another embodiment of the present application, the control device is specifically configured to calculate the expected DC voltage parameter of the first power conversion device according to the average AC voltage parameter in S202, and the method further includes:

[0123] According to the preset DC voltage limit range of the first power conversion device, the expected DC voltage parameter is limited.

[0124] For example, the preset DC voltage limit range is a preset range. For example, the preset DC voltage lower limit (Udc_lmt1_pcs1) is 0.9 times the DC voltage rated value (Udc_rate_pcs1), and the preset DC voltage upper limit (Udc_lmt2_pcs1) is 1.1 times the DC voltage rated value (Udc_rate_pcs1); the preset AC voltage lower limit (Uac_lmt1_pcs1) is 0.9 times the AC voltage rated value (Uac_rate_pcs1), and the preset AC voltage upper limit (Uac_lmt2_pcs1) is 1.1 times the AC voltage rated value (Uac_rate_pcs1).

[0125] According to the average AC voltage parameter, the expected DC voltage parameter of the first power conversion device is calculated, and the first power conversion device is controlled based on the expected DC voltage parameter.

[0126] Figure 8 A schematic diagram of adjusting a DC voltage according to an AC voltage according to an embodiment of the present application. Figure 8 As shown, the expected DC voltage is proportional to the average AC voltage parameter, and the expected DC voltage increases as the average AC voltage parameter increases, and decreases as the average AC voltage parameter decreases. The expected DC voltage parameter is controlled within a preset DC voltage limit range.

[0127] In summary, in this embodiment, the control device is specifically used to: perform amplitude limiting processing on the expected DC voltage parameter according to the preset DC voltage limit range of the first power conversion device. Thus, the expected DC voltage is amplitude limited and stabilized by the preset DC voltage limit range.

[0128] On the basis of the above embodiment, in another embodiment of the present application, the control device is specifically used to determine the second control parameter of the second power conversion device according to the detected DC voltage parameter in S104, including:

[0129] According to the detected DC voltage parameter and the real-time operating power parameter of the second power conversion device, the expected compensation power parameter of the second power conversion device is calculated, and the second control parameter includes: the expected compensation power parameter.

[0130] In summary, in this embodiment, the control device is specifically used to calculate the expected compensation power parameters of the second power conversion device according to the detected DC voltage parameters and the real-time operating power parameters of the second power conversion device, and the second control parameters include: the expected compensation power parameters.

[0131] On the basis of the above-mentioned embodiment, the embodiment of the present application further provides a method for calculating the expected compensation power parameter of the second power conversion device. Fig. 9 A flowchart of a method for calculating a desired compensation power parameter of a second power conversion device provided in an embodiment of the present application.

[0132] like Fig. 9 As shown, the control device is specifically used to calculate the expected compensation power parameter of the second power conversion device according to the detected DC voltage parameter and the real-time operating power parameter of the second power conversion device, including:

[0133] S501, calculating a lower limit compensation power parameter of the second power conversion device according to a lower limit DC voltage parameter of the second power conversion device, a detected DC voltage parameter, a real-time operating power parameter, and a preset voltage power adjustment step of the second power conversion device.

[0134] For example, the calculation method of the lower limit compensation power parameter of the second power conversion device is shown in the following formula (6):

[0135] Pset1_pcs2=(Udc_lmt1_pcs2-Udc_run_pcs2)×Udc_step1_pcs2+Prun_pcs2(6)

[0136] Among them, Pset1_pcs2 is the lower limit compensation power parameter of the second power conversion device, Udc_lmt1_pcs2 is the lower limit DC voltage parameter of the second power conversion device, Udc_run_pcs2 is the detection DC voltage parameter, Prun_pcs2 is the real-time operation power parameter, and Udc_step1_pcs2 is the preset voltage power adjustment step of the second power conversion device. The unit of the preset voltage power adjustment step is: Watt / Volt.

[0137] S502 , calculating an upper limit compensation power parameter of the second power conversion device according to an upper limit DC voltage parameter of the second power conversion device, a detected DC voltage parameter, a real-time operating power parameter, and a preset voltage power adjustment step.

[0138] For example, the upper limit compensation power parameter of the second power conversion device is calculated as shown in the following formula (7):

[0139] Pset2_pcs2=(Udc_lmt2_pcs2-Udc_run_pcs2)×Udc_step1_pcs2+Prun_pcs2(7)

[0140] Among them, Pset2_pcs2 is the upper limit compensation power parameter of the second power conversion device, Udc_lmt2_pcs2 is the upper limit DC voltage parameter of the second power conversion device, Udc_run_pcs2 is the detection DC voltage parameter, Prun_pcs2 is the real-time operation power parameter, and Udc_step1_pcs2 is the preset voltage power adjustment step of the second power conversion device.

[0141] S503: Calculate an expected compensation power parameter according to the lower compensation power parameter and the upper compensation power parameter.

[0142] For example, the calculation method of the expected compensation power parameter is shown in the following formula (8):

[0143] Pset_total_pcs2=Pset1_pcs2+Pset2_pcs2 (8)

[0144] Among them, Pset_total_pcs2 is the expected compensation power parameter.

[0145] It should be noted that if the expected compensation power parameter is positive, it indicates that the second power conversion device charges the energy storage device, and if the expected compensation power parameter is negative, it indicates that the energy storage device discharges to the second power conversion device. Regardless of whether the energy storage device is charging / discharging, the expected compensation power parameter is kept in a stable state.

[0146] Therefore, by taking the real-time operating power parameters as reference values ​​and gradually controlling the adjustment with a preset voltage and power adjustment step, accurate calculation of the desired compensation power parameters is achieved.

[0147] In summary, in this embodiment, the control device is specifically used to: calculate the lower limit compensation power parameter of the second power conversion device according to the lower limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operation power parameter, and the preset voltage power adjustment step of the second power conversion device; calculate the upper limit compensation power parameter of the second power conversion device according to the upper limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operation power parameter, and the preset voltage power adjustment step; calculate the expected compensation power parameter according to the lower limit compensation power parameter and the upper limit compensation power parameter. Thus, by taking the real-time operation power parameter as a reference value and gradually controlling and adjusting with the preset voltage power adjustment step, the expected compensation power parameter is accurately calculated.

[0148] In the above Fig. 9 On the basis of the corresponding embodiment, the embodiment of the present application further provides another method for calculating the expected compensation power parameter of the second power conversion device. Fig.10 A flowchart of another method for calculating a desired compensation power parameter of a second power conversion device provided in an embodiment of the present application.

[0149] like Fig.10 As shown, the control device is specifically used to calculate the expected compensation power parameter according to the lower compensation power parameter and the upper compensation power parameter in S503, including:

[0150] S601. Determine a rated lower limit compensation power parameter and a rated upper limit compensation power parameter of the second power conversion device according to a rated operating power parameter of the second power conversion device.

[0151] For example, based on the rated operating power parameter (Prate_pcs2) of the second power conversion device, it is determined that the rated lower limit compensation power parameter of the second power conversion device is (-Prate_pcs2), and the rated upper limit compensation power parameter is Prate_pcs2.

[0152] S602: According to the rated lower compensation power parameter and the rated upper compensation power parameter, respectively, limit the lower compensation power parameter and the upper compensation power parameter.

[0153] For example, the limiting range of the lower compensation power parameter is determined to be (-Prate_pcs2, 0), and the limiting range of the upper compensation power parameter is determined to be (0, Prate_pcs2).

[0154] S603: Calculate a total compensation power parameter according to the lower compensation power parameter and the upper compensation power parameter after the limiting process.

[0155] The total compensation power parameter is calculated by adding the lower compensation power parameter and the upper compensation power parameter after the limiting process.

[0156] S604: According to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter, the total compensation power parameter is limited to obtain the expected compensation power parameter.

[0157] For example, based on the clipping range of the lower compensation power parameter and the clipping range of the upper compensation power parameter, the clipping range of the total compensation power parameter is determined to be: (-Prate_pcs2, Prate_pcs2).

[0158] No matter the expected compensation power parameter is positive or negative, the expected compensation power parameter is kept within the limit range of the total compensation power parameter.

[0159] Fig.11 A schematic diagram of adjusting the expected compensation power of the second power conversion device according to the DC voltage value provided in an embodiment of the present application. Fig.11 As shown, with the DC voltage rated value (Udc_rate_pcs2) of the second power conversion device as a reference, the DC voltage is adjusted to (Udc_lmt1_pcs1, Udc_lmt2_pcs1) so that the desired compensation power parameter is within the limit range (-Prate_pcs2, Prate_pcs2) of the total compensation power parameter.

[0160] It should be noted that when the DC voltage is within (Udc_lmt1_pcs1, Udc_lmt2_pcs1), no further adjustment is performed.

[0161] In summary, in this embodiment, the control device is specifically used to: determine the rated lower limit compensation power parameter and the rated upper limit compensation power parameter of the second power conversion device according to the rated operating power parameter of the second power conversion device; perform amplitude limiting processing on the lower limit compensation power parameter and the upper limit compensation power parameter according to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter; calculate the total compensation power parameter according to the lower limit compensation power parameter and the upper limit compensation power parameter after amplitude limiting processing; perform amplitude limiting processing on the total compensation power parameter according to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter to obtain the expected compensation power parameter. Thus, the expected compensation power parameter is kept within the amplitude limiting range of the total compensation power parameter.

[0162] In another embodiment of the present application, the control device may be a device with computing and processing functions.

[0163] The control device includes: a processor and a storage medium. The processor and the storage medium are connected via a bus.

[0164] The storage medium is used to store the program, and the processor calls the program stored in the storage medium to execute the above method embodiment. The specific implementation method and technical effect are similar and will not be repeated here.

[0165] Optionally, the present invention also provides a storage medium, including a program, which is used to execute the above-mentioned method embodiment when executed by a processor. In the several embodiments provided by the present invention, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0166] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0167] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0168] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (English: processor) to perform some steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (English: Read-Only Memory, abbreviated: ROM), random access memory (English: Random Access Memory, abbreviated: RAM), disk or optical disk and other media that can store program codes.

Claims

1. A distributed energy storage system, characterized in that: The distributed energy storage system comprises: a first power conversion device, a second power conversion device and a control device; The AC end of the first power conversion device is connected to a transformer in a preset station area, the DC end of the first power conversion device is connected to a first DC end of the second power conversion device, and the second DC end of the first power conversion device is used to connect to an energy storage device; The control device is connected to the first power conversion device and the second power conversion device respectively; The control device is used to: Acquiring three-phase AC voltage parameters of the AC end of the first power conversion device; Determining a first control parameter of the first power conversion device according to the three-phase AC voltage parameter to control a DC operating voltage at a DC end of the first power conversion device; Acquiring a detected DC voltage parameter of the first DC terminal of the second power conversion device; A second control parameter of the second power conversion device is determined according to the detected DC voltage parameter to control the operating power of the second power conversion device.

2. The distributed energy storage system according to claim 1, characterized in that: The control device includes: a first control unit and a second control unit, wherein the first control unit and the second control unit are respectively connected to the first power conversion device and the second power conversion device to control the first power conversion device and the second power conversion device respectively.

3. The distributed energy storage system according to claim 2, characterized in that: The distributed energy storage system also includes: an energy storage device, a fire protection device, and a thermal management device; The second control unit is respectively connected to the energy storage device, the fire fighting device, and the thermal management device; The second DC end of the second power conversion device is connected to the DC end of the energy storage device.

4. The distributed energy storage system according to claim 1, characterized in that: The control device is specifically used for: Calculating an average AC voltage parameter according to the three-phase AC voltage parameter; According to the average AC voltage parameter, an expected DC voltage parameter of the first power conversion device is calculated, and the first control parameter includes: the expected DC voltage parameter.

5. The distributed energy storage system according to claim 4, characterized in that: The control device is specifically used for: Calculating an AC voltage deviation parameter of the first power conversion device according to the average AC voltage parameter and a preset AC voltage rated parameter of the first power conversion device; The expected DC voltage parameter is calculated according to the AC voltage deviation parameter, a preset AC-DC conversion step size of the first power conversion device, and a preset DC voltage rated parameter of the first power conversion device.

6. The distributed energy storage system according to claim 4, characterized in that: The control device is specifically used for: Calculating three-phase AC voltage deviation parameters of the first power conversion device respectively according to the average AC voltage parameter and the three-phase AC voltage parameter; According to the three-phase AC voltage deviation parameter, the three-phase real-time operating power of the first power conversion device, and the preset AC voltage power adjustment step, the three-phase expected power parameters of the first power conversion device are calculated respectively, and the first control parameter also includes: the three-phase expected power parameters.

7. The distributed energy storage system according to claim 4, characterized in that: The control device is specifically used for: The expected DC voltage parameter is limited according to a preset DC voltage limit range of the first power conversion device.

8. The distributed energy storage system according to claim 1, characterized in that: The control device is specifically used for: According to the detected DC voltage parameter and the real-time operating power parameter of the second power conversion device, the expected compensation power parameter of the second power conversion device is calculated, and the second control parameter includes: the expected compensation power parameter.

9. The distributed energy storage system according to claim 8, characterized in that: The control device is specifically used for: Calculating a lower limit compensation power parameter of the second power conversion device according to the lower limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operating power parameter, and a preset voltage power adjustment step of the second power conversion device; Calculating an upper limit compensation power parameter of the second power conversion device according to the upper limit DC voltage parameter of the second power conversion device, the detected DC voltage parameter, the real-time operating power parameter, and the preset voltage power adjustment step; The expected compensation power parameter is calculated according to the lower compensation power parameter and the upper compensation power parameter.

10. The distributed energy storage system according to claim 9, characterized in that: The control device is specifically used for: determining a rated lower limit compensation power parameter and a rated upper limit compensation power parameter of the second power conversion device respectively according to the rated operating power parameter of the second power conversion device; According to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter, respectively, the lower limit compensation power parameter and the upper limit compensation power parameter are subjected to amplitude limiting processing; Calculate the total compensation power parameter according to the lower compensation power parameter and the upper compensation power parameter after the limiting process; The total compensation power parameter is limited according to the rated lower limit compensation power parameter and the rated upper limit compensation power parameter to obtain the expected compensation power parameter.

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