Synchronous control device and method for large-scale battery energy storage system

Abstract

The present application provides a synchronous control device and method for a large-scale battery energy storage system, the device comprising: a first information interaction network, connected to an energy storage converter unit of the energy storage system; at least two sub-control units, connected to the first information interaction network, each sub-control unit coordinates and controls at least two of the energy storage converter units through the first information interaction network; a second information interaction network, connected to the sub-control units; a central control unit, connected to the second information interaction network, obtains the operating status of the energy storage converter unit through the first information interaction network, the sub-control unit, and the second information interaction network, and sends the active power instruction and reactive power instruction included in the synchronous control instruction to the central control unit. Coordinated control through a hierarchical control architecture can flexibly cope with the expansion of the large-scale energy storage converter system; indirect control of the energy storage converter unit through active power and reactive power instructions reduces the complexity of synchronous control of the large-scale energy storage system.

Description

Technical Field

[0001] The present application relates to the technical field of grid-connected operation of battery energy storage systems, and specifically to a synchronization control device and method for large-scale battery energy storage systems. Background Art

[0002] With the large-scale development of renewable energy, its randomness and intermittency have brought severe challenges to the operation and control of the power grid. Battery energy storage can significantly improve the absorption level of renewable energy such as wind and light, and enhance the flexibility, economy and safety of traditional power systems. In addition, the energy storage system can also operate off-grid, and can serve as the main power source in the event of a power grid failure or in remote areas with high seas, supplying power to local loads and facilitating the access of new energy.

[0003] When the battery energy storage system is operating off-grid, its operating parameters such as voltage amplitude and phase are different from those of the grid. When the grid is normal and the energy storage system needs to be connected to the grid, the energy storage system must be synchronously controlled to avoid system failures due to large switching-on impact currents. Limited by the power of the single-unit energy storage converter (PCS) in the energy storage unit, large-scale battery energy storage systems are generally composed of multiple PCSs in parallel. It is very difficult to synchronously control the coordinated operation of multiple PCSs, and it is very easy to cause system instability or synchronization failure.

[0004] The existing synchronous control methods have the following problems: (1) The synchronous control is only for a single energy storage inverter, and the synchronous control is achieved by adjusting the off-grid voltage amplitude and frequency. Due to the existence of frequency changes, this method has the risk of causing system instability when applied to large-scale energy storage systems; (2) The control architecture of large-scale energy storage systems is unreasonable, with many intermediate communication conversion links and obvious delays, resulting in poor real-time synchronization control; (3) Before and after synchronous grid connection, the information exchange between the synchronous control device and the energy storage unit needs to be switched, and the control logic is complex. For example, before grid-connected operation, the two exchange active power instructions and reactive power instructions, and during off-grid operation, they exchange voltage amplitude instructions and voltage frequency instructions. Summary of the invention

[0005] The present application aims to provide a synchronization control device and control method for a large-scale battery energy storage system. The synchronization control device adopts a hierarchical architecture to coordinate and control multiple energy storage converter units, and utilizes the droop control characteristics of the energy storage converter to achieve smooth control of the voltage frequency and voltage amplitude of the energy storage converter unit through active power and reactive power, thereby achieving information interaction and sharing before and after synchronization, and improving the reliability of synchronization control.

[0006] According to one aspect of the present application, the present application provides a synchronization control device for a large-scale battery energy storage system, comprising:

[0007] A first information interaction network connected to the energy storage converter unit of the energy storage system;

[0008] At least two sub-control units are connected to the first information interaction network, and each of the sub-control units coordinates and controls at least two of the energy storage and current conversion sub-units through the first information interaction network;

[0009] A second information exchange network connected to the sub-control unit;

[0010] The central control unit is connected to the second information interaction network, obtains the operating status of the energy storage converter unit through the first information interaction network, the sub-control unit and the second information interaction network, and sends the active power instruction and reactive power instruction included in the synchronous control instruction to the central control unit.

[0011] According to some embodiments of the present application, the central control unit obtains synchronization instructions in an off-grid operation state and collects operating parameters of the energy storage system through a secondary cable.

[0012] According to some embodiments of the present application, the operating status includes: normal operation, abnormal operation, and the number of energy storage converter units that are operating normally.

[0013] According to some embodiments of the present application, the operating parameters include: one or more of: AC bus voltage of the energy storage system, grid voltage, and common connection point switch position.

[0014] According to some embodiments of the present application, the central control unit includes:

[0015] An information acquisition module, used to obtain the synchronization instruction, the operation status, and the operation parameters;

[0016] A synchronous control module, used to perform synchronous logic control operations according to the operating state and operating parameters, and generate the synchronous control instructions;

[0017] The instruction output module is used to output the synchronous control instruction.

[0018] Furthermore, the active power instruction includes a system active power instruction and a unit active power instruction; the reactive power instruction includes a system reactive power instruction and a unit reactive power instruction.

[0019] According to some embodiments of the present application, the synchronous logic control operation includes:

[0020] The system active power command value and system reactive power command value are calculated according to the following formula:

[0021]

[0022] Among them, Pset_sys is the system active power command value, Q set_sys is the system reactive power command value, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, G u (s), G x (s) are the transfer functions of the active regulator and reactive regulator respectively;

[0023] The unit active power command value and unit reactive power command value of each energy storage converter unit are calculated according to the following formula:

[0024]

[0025]

[0026] Where i is the serial number of the energy storage converter unit, λ(i) is the operating state parameter value of the energy storage converter unit i, and P set (i) is the unit active power command value of the energy storage converter unit i, Q set (i) is the reactive power command value of the energy storage converter unit i, j is the number of energy storage converter units in normal operation, j is an integer, j ≥ 2; S rate (i) is the rated capacity of energy storage converter unit i.

[0027] According to some embodiments of the present application, the active power regulator and the reactive power regulator include: an integral regulator or a proportional integral regulator.

[0028] According to some embodiments of the present application, the synchronization instruction includes: a synchronization instruction sent by an external control system or a localized synchronization instruction.

[0029] According to some embodiments of the present application, the synchronous control instruction further includes:

[0030] An operating mode instruction sent to the energy storage converter unit; and / or

[0031] A switch control instruction is sent to the common connection point switch.

[0032] The present application also provides a synchronization control method for a large-scale battery energy storage system, comprising:

[0033] In the off-grid operation state, the central control unit obtains synchronization instructions, operating parameters of the energy storage system, and operating status of the energy storage converter unit in the energy storage system;

[0034] After the synchronization instruction is set, the central control unit performs synchronization logic control operations according to the operating parameters and operating status to generate synchronization control instructions;

[0035] The central control unit sends the generated active power instruction and reactive power instruction to the energy storage converter unit of the energy storage system through hierarchical interaction.

[0036] According to some embodiments of the present application, the hierarchical interaction includes:

[0037] The central control unit sends the active power instruction and the reactive power instruction to the sub-control unit corresponding to the energy storage converter unit through the second information interaction network;

[0038] The sub-control unit sends the active power instruction and the reactive power instruction to the energy storage conversion sub-unit through the first information interaction network.

[0039] According to some embodiments of the present application, the operating parameters include: one or more of: AC bus voltage of the energy storage system, grid voltage, and common connection point switch position.

[0040] According to some embodiments of the present application, the operating status includes: normal operation, abnormal operation, and the number of energy storage converter units that are operating normally.

[0041] According to some embodiments of the present application, the active power instruction includes a system active power instruction and a unit active power instruction; the reactive power instruction includes a system reactive power instruction and a unit reactive power instruction.

[0042] According to some embodiments of the present application, the synchronous logic control operation includes:

[0043] The system active power command value and system reactive power command value are calculated according to the following formula:

[0044]

[0045] Among them, P set_sys is the system active power command value, Q set_sys is the system reactive power command value, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, G u (s), G x (s) are the transfer functions of the active regulator and reactive regulator respectively;

[0046] The unit active power command value and unit reactive power command value of each energy storage converter unit are calculated according to the following formula:

[0047]

[0048]

[0049] Where i is the serial number of the energy storage converter unit, λ(i) is the operating state parameter value of the energy storage converter unit i, and P set (i) is the unit active power command value of the energy storage converter unit i, Q set (i) is the reactive power command value of the energy storage converter unit i, j is the number of energy storage converter units in normal operation, j is an integer, j ≥ 2; S rate (i) is the rated capacity of energy storage converter unit i.

[0050] According to some embodiments of the present application, the active power regulator and the reactive power regulator include: an integral regulator or a proportional integral regulator.

[0051] According to some embodiments of the present application, the synchronization control method further includes:

[0052] The obtained AC bus voltage of the energy storage system and the grid voltage are used to determine the synchronization completion status according to the following synchronization completion formula:

[0053]

[0054] Among them, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, u q_sync , X u_sync It is the preset value for judging the completion of synchronization.

[0055] Furthermore, the simultaneous completion status judgment includes:

[0056] When the AC bus voltage of the energy storage system and the grid voltage satisfy the synchronization completion formula, it is determined that the energy storage system enters the first synchronization completion state.

[0057] According to some embodiments of the present application, the simultaneous completion status determination further includes:

[0058] After entering the first state of synchronization completion, after a delay, when the AC bus voltage and the grid voltage of the energy storage system meet the synchronization completion formula, it is determined that the energy storage system enters the second state of synchronization completion.

[0059] According to some embodiments of the present application, the synchronous control instruction also includes: an operation mode instruction and / or a switch control instruction.

[0060] Furthermore, the synchronous control method further includes:

[0061] When the energy storage system enters the first state of synchronous completion or the second state of synchronous completion, the central control unit sends the switch control instruction to the common connection point switch.

[0062] According to some embodiments of the present application, the synchronization control method further includes:

[0063] When the acquired common connection point switch position is closed, the operation mode instruction is sent to the energy storage converter unit through the first information interaction network and the second information interaction network.

[0064] According to some embodiments of the present application, the synchronization instruction includes: a synchronization instruction sent by an external control system or a localized synchronization instruction.

[0065] The present application also provides an electronic device, comprising: one or more processors; a storage device for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the synchronous control method as described above.

[0066] The present application also provides a computer-readable medium having a computer program stored thereon. When the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned synchronous control method.

[0067] The synchronous control device and control method for a large-scale battery energy storage system provided in the present application adopts a hierarchical architecture to coordinate and control multiple energy storage converter units, which can flexibly cope with the expansion of the energy storage system. By utilizing the droop control characteristics of the energy storage converter in the energy storage converter unit, the energy storage converter unit is indirectly controlled by outputting active power and reactive power instructions, avoiding the switching of control instructions under different off-grid and grid-connected working conditions, and reducing the control complexity of the large-scale energy storage system.

[0068] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application.

[0070] Figure 1 A schematic diagram of a large-scale battery energy storage system according to an exemplary embodiment of the present application is shown.

[0071] Figure 2 A schematic diagram showing the composition of a synchronization control device according to an exemplary embodiment of the present application is shown.

[0072] Figure 3 A block diagram of a central control unit according to an exemplary embodiment of the present application is shown.

[0073] Figure 4 A schematic diagram of data processing of a central control unit according to an exemplary embodiment of the present application is shown.

[0074] Figure 5 A flow chart of a synchronous control method according to an exemplary embodiment of the present application is shown.

[0075] Figure 6 A schematic diagram of synchronous control logic operation according to an exemplary embodiment of the present application is shown.

[0076] Figure 7 A flow chart of a synchronous control process according to an exemplary embodiment of the present application is shown.

[0077] Figure 8 A diagram showing the composition of a synchronous control electronic device according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0078] Example embodiments will be described more fully below with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as being limited to the embodiments set forth herein. These embodiments are provided to make this application more comprehensive and complete and to fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0079] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0080] It should be understood that although the terms first, second, etc. may be used herein to describe various components, these components should not be limited by these terms. These terms are used to distinguish one component from another component. Therefore, the first component discussed below can be referred to as the second component without departing from the teachings of the concepts of the present application. As used herein, the term "and / or" includes any one of the associated listed items and all combinations of one or more.

[0081] Those skilled in the art will appreciate that the drawings are only schematic diagrams of example embodiments and may not be to scale. The modules or processes in the drawings are not necessarily required to implement the present application and therefore cannot be used to limit the scope of protection of the present application.

[0082] In view of the delay problem caused by the unreasonable synchronous control architecture of the existing large-scale battery energy storage system, and the information interaction between the existing synchronous control device and the energy storage converter unit needs to be switched before and after synchronization, the inventor proposes a synchronous control device and control method for a large-scale battery energy storage system, which adopts a hierarchical architecture to coordinate and control multiple energy storage converter units, and can flexibly respond to the expansion of the energy storage system. Generate active power and reactive power instructions for synchronous control, and use the droop control characteristics of the energy storage converter to indirectly control the voltage amplitude, frequency and phase of the energy storage system, avoiding the switching of control instructions under different off-grid and grid-connected working conditions, and reducing the control complexity of the large-scale energy storage system.

[0083] The technical solution of the present application will be described in detail below with reference to the accompanying drawings.

[0084] Figure 1 A schematic diagram of a large-scale battery energy storage system according to an exemplary embodiment of the present application is shown.

[0085] like Figure 1 As shown, according to an example embodiment of the present application, a large-scale battery energy storage system 1000 includes a monitoring system 100, a synchronization control device 200, and an energy storage conversion unit 300. The monitoring system 100 is connected to the synchronization control device 200 and the energy storage conversion unit 300 through a monitoring communication network, and is used to transmit synchronization instructions to the synchronization control device 200 and monitor the operating status of the energy storage conversion unit 300. The synchronization control device 200 is connected to the energy conversion unit 300 through a control communication network, and is used to transmit synchronization control instructions. In the large-scale battery energy storage system, the energy storage conversion unit 300 is composed of more than two energy storage conversion sub-units 310. Each energy storage conversion sub-unit 310 includes an energy storage inverter 311 and an energy storage battery 312.

[0086] The energy storage system 1000 is connected to the grid through a step-up transformer and a common connection point switch 400. When the common connection point switch 400 is disconnected, the energy storage system 1000 is in an off-grid state. When the common connection point switch 400 is closed, the energy storage system 1000 is in a grid-connected state. The synchronization control device 200 is connected to the main power circuit through a secondary cable (not shown in the figure) to collect the AC bus voltage, grid voltage and common connection point switch position information of the energy storage system.

[0087] Figure 2 A schematic diagram showing the composition of a synchronization control device according to an exemplary embodiment of the present application is shown.

[0088] like Figure 2 As shown, according to some embodiments of the present application, the synchronization control device 200 for a large-scale battery energy storage system provided by the present application includes a central control unit 210, a second information interaction network 220, at least two sub-control units 230, and a first information interaction network 240.

[0089] A first information interaction network 240, connected to the energy storage converter unit 310 of the energy storage system;

[0090] The sub-control unit 230 is connected to the first information interaction network 240, and each of the sub-control units 230 coordinates and controls at least two of the energy storage and current conversion sub-units 310 through the first information interaction network 240;

[0091] A second information interaction network 220, connected to the sub-control unit 230;

[0092] The central control unit 210 is connected to the second information interaction network 220, and obtains the operating status of the energy storage conversion subunit 310 through the first information interaction network 240, the sub-control unit 230 and the second information interaction network 220, and sends synchronous control instructions including active power instructions and reactive power instructions to it.

[0093] The central control unit 210 obtains synchronization instructions, operating parameters of the energy storage system, and operating status of the energy storage converter unit in the energy storage system in an off-grid operating state, and generates synchronization control instructions according to the synchronization instructions, operating parameters, and operating status.

[0094] The sub-control unit 230 is connected to the central control unit 210 via the second information exchange network 220, receives the synchronous control instruction issued by the central control unit 210, and uploads the acquired operating status to the central control unit 210. In addition, each sub-control unit 230 is connected to at least two energy storage converter units 310 of the energy storage system via the first information exchange network 240, acquires the operating status and sends the received synchronous control instruction to the energy storage converter unit 310. Figure 2In the synchronous control device 200 shown, the number of sub-control units 230 is M, M≥2. According to the current processing capability of the central control unit hardware, M≤128, but the present application is not limited thereto. Specifically, the number of each sub-control unit can be represented as 230-1, 230-m, 230-M, etc., where M>m>1. Each sub-control unit 230 corresponds to an energy storage conversion unit 300, that is, the number of energy storage conversion units 300 is the same as that of the sub-control units 230. Similarly, the number of each energy storage conversion unit 300 can be represented as 300-1, 300-m, 300-M, etc. Each energy storage conversion unit 300 includes p energy storage conversion sub-units 310, that is, the number of energy storage conversion sub-units 310 controlled by each sub-control unit 230 is p, p≥2. Similarly, according to the current processing capability of the sub-control unit hardware, p≤128, but the present application is not limited thereto. Then, the number of each energy storage converter unit 310 can be represented as 310-1-1, 310-1-p, 310-m-1, 310-mp, 310-M-1, 310-Mp, etc.

[0095] Specifically, during the operation of the synchronization control device 200, the central control unit 210 receives synchronization instructions from the external control system, and may also receive localized synchronization instructions (for example, synchronization instructions are input on the interactive interface of the synchronization control device). After detecting that the synchronization instruction is set, the synchronization control device enters synchronization control.

[0096] The central control unit 210 and the sub-control unit 230 constitute the second information exchange network 220; the sub-control unit 230 and the energy storage converter sub-unit 310 constitute the first information exchange network 240. During the synchronous control process, the central control unit 210 collects the operating parameters of the energy storage system, including one or more of the information such as the AC bus voltage of the energy storage system, the grid voltage, and the position of the common connection point switch. The opening and closing of the common connection point switch controls the off-grid and on-grid connection.

[0097] The central control unit 210 sends synchronization control command information to the sub-control unit 230 through the second information interaction network 220 , and receives the operating status of the energy storage converter sub-unit 310 uploaded by the sub-control unit 230 through the second information interaction network 220 .

[0098] The sub-control unit 230 receives the synchronous control command information sent by the central control unit 210 through the second information interaction network 220, and sends the operating status of the energy storage inverter sub-unit 310 to the central control unit 210 through the second information interaction network 220. In addition, the sub-control unit 230 also obtains the operating status of the energy storage inverter sub-unit 310 through the first information interaction network 240, and sends the synchronous control command information to the energy storage inverter sub-unit 310 through the first information interaction network 240. The synchronous control instruction includes one or more of: system active power instruction, system reactive power instruction, unit active power instruction, unit reactive power instruction, operation mode instruction, and switch control instruction.

[0099] Figure 3 A block diagram of a central control unit according to an exemplary embodiment of the present application is shown.

[0100] Figure 4 A schematic diagram of data processing of a central control unit according to an exemplary embodiment of the present application is shown.

[0101] According to some embodiments of the present application, Figure 3 As shown, the central control unit 210 includes an information acquisition module 211 , a synchronization control module 212 and an instruction output module 213 .

[0102] like Figure 4 As shown, the information acquisition module 211 is used to obtain the synchronization instruction, the operating status, and the operating parameters. Specifically, when the external power grid fails and the energy storage system is off-grid, the information acquisition module 211 collects the AC bus voltage and grid voltage information of the energy storage system, and at the same time receives the operating status of the energy storage converter unit uploaded by the sub-control unit 230, and obtains the operating status of each energy storage converter unit in real time. The operating status includes the total number of energy storage converter units that are online in each energy storage converter unit. When the external power grid returns to normal and the energy storage system needs to be connected to the grid, a synchronization instruction can be sent to the central control unit through remote or local control, and the information acquisition unit 211 receives the synchronization instruction. At the same time, the information acquisition module 211 collects the switch position information of the common connection point to determine the actual state of the switch.

[0103] The synchronization control module 212 is used to perform synchronization logic control operations (described in detail below) according to the operating state and operating parameters to generate the synchronization control instructions. The synchronization control module 212 sends the generated synchronization control instructions to the instruction output module 213. The synchronization control module 212 is also used to determine the synchronization completion status. That is, when it is determined that the system has completed the synchronization process, it waits for the grid connection operation.

[0104] The instruction output unit module is used to output the synchronization control instruction. For example, after the instruction output module 213 receives the synchronization control instruction sent by the synchronization control unit 212, it sends the unit active power instruction, the unit reactive power instruction and the operation mode instruction of the energy storage converter sub-unit to the sub-control unit through the second information interaction network. After it is determined that the synchronization is completed, the switch control instruction is sent to the common connection point switch to control the switch to close, and the energy storage system enters the grid-connected operation.

[0105] Figure 5 A flow chart of a synchronous control method according to an exemplary embodiment of the present application is shown.

[0106] Figure 6 A schematic diagram of synchronous control logic operation according to an exemplary embodiment of the present application is shown.

[0107] According to some embodiments of the present application, the present application also provides a synchronization control method for a large-scale battery energy storage system, which is applied to the above-mentioned synchronization control device. Figure 5 As shown, the synchronous control method includes:

[0108] In step S510, in an off-grid operating state, the central control unit obtains synchronization instructions, operating parameters of the energy storage system, and operating status of an energy storage converter unit in the energy storage system.

[0109] When the energy storage system is in off-grid operation, the central control unit receives synchronization instructions sent by the external system or local synchronization instructions. The information acquisition module of the central control unit collects the three-phase voltage u of the AC busbar of the energy storage system. sa 、u sb 、u sc , three-phase voltage of power grid u ga 、u gb 、u gc , and system operating parameters such as the switch position of the common connection point. In addition, the central control unit obtains the operating status of each energy storage converter unit through the first information interaction network and the second information interaction network, including the number of energy storage converter units that are operating normally, operating abnormally, and operating normally.

[0110] In step S520, after the synchronization instruction is set, the central control unit performs synchronization logic control operations according to the operating parameters and the operating state to generate synchronization control instructions including active power instructions and reactive power instructions.

[0111] If the information acquisition module of the central control unit detects that the synchronization instruction is not set, the off-grid operation state will continue. If the synchronization instruction is detected to be set, the system enters the synchronization process. After entering the synchronization process, the synchronization control module of the central control unit performs synchronization logic control operations on the operating parameters and operating status to generate synchronization control instructions. The synchronization control instructions include one or more of the system active power instructions, system reactive power instructions, unit active power instructions, system reactive power instructions, operation mode instructions, and switch control instructions.

[0112] like Figure 6 As shown in the figure, the specific process of synchronous logic control operation is as follows:

[0113] The synchronous control module of the central control unit collects the three-phase voltage u of the AC busbar of the energy storage system sa 、u sb 、u sc , three-phase voltage of power grid u ga 、u gb 、u gc , the voltage phase angle θ of the energy storage system is calculated through the phase-locked loop PLL s Then, the AC bus voltage and grid voltage of the energy storage system are transformed according to the following formula, and the components in the synchronous coordinate system are obtained based on the AC bus voltage phase of the energy storage system:

[0114]

[0115] Then calculate the amplitude X of the voltage vector based on the voltage component u , the expression is:

[0116]

[0117] According to the above formula, the q-axis component u of the grid voltage in the AC bus voltage rotating coordinate system of the energy storage system can be calculated respectively: gq , and the voltage vector amplitude X of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system us , X ug .

[0118] u gq After adjustment by the PI controller with amplitude limiting function, the reactive power command value Q required for synchronous control of the energy storage system is obtained. set_sys .X us and X ug The difference is adjusted by a PI controller with a limiting function to obtain the active power command value P required for synchronous control of the energy storage system. set_sys The specific calculation formula is as follows:

[0119]

[0120] Among them, P set_sys is the system active power command value, Q set_sys is the system reactive power command value, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, G u (s), G x (s) are the transfer functions of the active regulator and reactive regulator, respectively. They can be integral regulators or proportional integral regulators. The PI controller limit is Wherein, j is the total number of energy storage converter units in normal operation, j is an integer, and j ≥ 2; S rate (i) is the rated capacity of energy storage converter unit i.

[0121] During the operation of the energy storage system, the unit active power command value and unit reactive power command value of each energy storage converter unit and the system active power command value and system reactive power command value satisfy the following relationship:

[0122]

[0123] Among them, P set_sys is the system active power command value, Q set_sys is the system reactive power command value, P set (i) is the unit active power command value of the energy storage converter unit i, Q set (i) is the unit reactive power command value of the energy storage converter unit i.

[0124] After obtaining the system active power command value and the system reactive power command value, the unit active power command value and the unit reactive power command value of each energy storage converter unit are calculated according to the following formula:

[0125]

[0126]

[0127] Where, i is the serial number of the energy storage converter unit, λ(i) is the operating state parameter value of the energy storage converter unit i, and P set (i) is the unit active power command value of the energy storage converter unit i, Q set (i) is the reactive power command value of the energy storage converter unit i, j is the number of energy storage converter units in normal operation, j is an integer, j ≥ 2; S rate(i) is the rated capacity of energy storage converter unit i.

[0128] In step S530, the central control unit sends the generated active power instructions and reactive power instructions to the energy storage converter subunit of the energy storage system through hierarchical interaction. The central control unit generates active power instructions and reactive power instructions including unit active power instructions and unit reactive power instructions. After generating the synchronous control instructions, the central control unit sends the unit active power instructions and unit reactive power instructions to the sub-control unit through the second information interaction network. The sub-control unit then sends the unit active power instructions and unit reactive power instructions to the corresponding energy storage converter subunits through the first information interaction network.

[0129] The energy storage converter unit receives the synchronous control instruction and generates a voltage amplitude instruction and a real-time frequency instruction of the energy storage converter unit according to the following formula based on the droop control characteristics:

[0130]

[0131] Among them, f ref (i) U ref (i) are the real-time frequency command and voltage amplitude command of off-grid operation of energy storage converter unit i, respectively, and f g , U g are the rated frequency and rated amplitude of the grid voltage, P o (i) Q o (i) are respectively the actual active power and reactive power of energy storage subunit i; i represents the serial number of the energy storage converter subunit, i is an integer, 1≤i≤n, n represents the number of energy storage converter subunits, n is an integer, n≥4. According to the current processing capacity of the central control unit and the sub-control unit hardware, n≤128×128, but the present application is not limited thereto.

[0132] In the synchronous control method provided by the present application, the energy storage converter unit is indirectly controlled by outputting active power instructions and reactive power instructions, rather than directly controlling the energy storage converter unit by outputting voltage amplitude and frequency amplitude. Through the indirect control of active power and reactive power instructions, the switching of control instructions between the coordinated control system and the energy storage converter device under different working conditions of off-grid operation and grid-connected operation of the energy storage system can be avoided, and the control instruction sharing can be realized, thereby reducing the complexity of synchronous control of large-scale energy storage systems.

[0133] According to some embodiments of the present application, the synchronization control method further includes determining the synchronization completion state of the acquired AC bus voltage of the energy storage system and the grid voltage according to the following synchronization completion formula:

[0134]

[0135] Among them, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, u q_sync , X u_sync It is the preset value for judging the completion of synchronization.

[0136] When the AC bus voltage of the energy storage system and the grid voltage satisfy the above synchronization completion formula, it is determined that the energy storage system enters the first synchronization completion state. According to some embodiments of the present application, after the system enters the first synchronization completion state, the grid connection instruction can be executed.

[0137] According to other embodiments of the present application, after entering the first state of synchronization completion, after a delay, when the AC bus voltage and the grid voltage of the energy storage system satisfy the above synchronization completion formula, it is determined that the energy storage system enters the second state of synchronization completion. At this time, when the system enters the second state of synchronization completion, it is considered that the system has stably completed the synchronization and the grid connection instruction can be executed.

[0138] When the energy storage system enters the first state of synchronization completion or the second state of synchronization completion, the central control unit sends the switch control instruction to the common connection point switch to close the common connection point switch, and the energy storage system enters the grid-connected operation state.

[0139] Figure 7 A flow chart of a synchronous control process according to an exemplary embodiment of the present application is shown.

[0140] like Figure 7 As shown, the process of performing synchronous control using the synchronous control device or synchronous control method provided by the present application is as follows:

[0141] In S610, the energy storage system operates off-grid, receives the synchronization instruction in real time, and determines whether the synchronization instruction is set. When the synchronization instruction is not set, the energy storage system continues to operate off-grid. When the synchronization instruction is set, the synchronization process is entered.

[0142] In S620, after the synchronization instruction is set and the synchronization process is entered, the synchronization control instruction is calculated and executed, and the synchronization completion status is judged based on the collected energy storage system AC bus voltage and grid voltage. The calculation and execution processes are as follows:

[0143] In S621, the central control unit calculates the system active power command P required for the system to be connected to the grid based on the acquired energy storage system AC bus voltage and grid voltage. set_sys , System reactive power command Q set_sys, and distribute it to each energy storage converter unit to obtain the unit active power instruction P of each energy storage converter unit set (i) and unit reactive power command Q set (i).

[0144] In S622, the energy storage converter units execute their respective unit active power instructions P set (i) and unit reactive power command Q set (i) During the execution, according to the droop control characteristics, the unit active power command P set (i) and unit reactive power command Q set (i) Obtaining a voltage amplitude command and a real-time frequency command. Each energy storage converter unit operates according to its own voltage amplitude command and real-time frequency command.

[0145] At S630, after determining that synchronization is completed, the central control unit sends a switch control instruction to close the common connection point switch. At the same time, the common connection point switch position information is collected in real time. If the common connection point switch is not closed in the collected common connection point switch position information, the synchronization process S620 is continued to be executed so that the system meets the synchronization conditions again.

[0146] At S640, after detecting that the common connection point switch has been closed, the energy storage system enters the grid-connected operation state. At this time, the central control unit sends a grid-connected operation mode instruction to each energy storage converter unit through the first information interaction network and the second information interaction network, and the energy storage converter unit is converted to PQ grid-connected operation. At this point, the energy storage system completes synchronous grid connection.

[0147] Figure 8 A block diagram of the synchronous control electronic device according to an exemplary embodiment of the present application is shown.

[0148] The present application also provides a synchronization control electronic device 700 for a large-scale battery energy storage system. Figure 8 The control device 700 shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0149] like Figure 8 As shown, the control device 700 is in the form of a general computing device. The components of the control device 700 may include, but are not limited to: at least one processing unit 710, at least one storage unit 720, a bus 730 connecting different system components (including the storage unit 720 and the processing unit 710), etc.

[0150] The storage unit 720 stores program codes, and the program codes can be executed by the processing unit 710, so that the processing unit 710 executes the methods described in this specification according to the above embodiments of the present application.

[0151] The storage unit 720 may include a readable medium in the form of a volatile storage unit, such as a random access storage unit (RAM) 7201 and / or a cache storage unit 7202 , and may further include a read-only storage unit (ROM) 7203 .

[0152] The storage unit 720 may also include a program / utility 7204 having a set (at least one) of program modules 7205, such program modules 7205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0153] Bus 730 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0154] The electronic device 700 may also communicate with one or more external devices 7001 (e.g., a touch screen, a keyboard, a pointing device, a Bluetooth device, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 700, and / or communicate with any device that enables the electronic device 700 to communicate with one or more other computing devices (e.g., a router, a modem, etc.). Such communication may be performed via an input / output (I / O) interface 750. Furthermore, the electronic device 700 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) via a network adapter 760. The network adapter 760 may communicate with other modules of the electronic device 700 via a bus 730. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 700, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems, etc.

[0155] In addition, the present application also provides a computer-readable medium on which a computer program is stored, and when the program is executed by a processor, the above-mentioned synchronization control method is implemented.

[0156] The synchronous control device and control method for a large-scale battery energy storage system provided in the present application have a control architecture that can flexibly respond to the expansion of the energy storage system and can perform group adjustment and group control of multiple energy storage inverter units. By sharing active power command and reactive power command control information between the coordinated control system and the energy storage inverter units under different operating conditions of off-grid operation and grid-connected operation of the energy storage system, the control complexity of the large-scale energy storage system is reduced. In addition, based on the droop control characteristics, the off-grid voltage amplitude, frequency and phase are indirectly controlled by active power and reactive power, and a closed-loop regulator is used to achieve rapid and accurate adjustment of the voltage amplitude, frequency and phase, thereby improving synchronization reliability.

[0157] Obviously, the above embodiments are only examples for clearly explaining the present application, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the present application.

Claims

1. A synchronization control device for a large-scale battery energy storage system, characterized in that: include: A first information interaction network connected to the energy storage converter unit of the energy storage system; At least two sub-control units are connected to the first information interaction network, and each of the sub-control units coordinates and controls at least two of the energy storage and current conversion sub-units through the first information interaction network; A second information exchange network connected to the sub-control unit; A central control unit is connected to the second information interaction network, obtains the operating status of the energy storage converter subunit through the first information interaction network, the sub-control unit and the second information interaction network, and sends the active power instruction and reactive power instruction included in the synchronization control instruction to the subunit, the central control unit obtains the synchronization instruction in the off-grid operation state, and collects the operating parameters of the energy storage system through the secondary cable, wherein the central control unit includes: An information acquisition module, used to obtain the synchronization instruction, the operation status, and the operation parameters; A synchronous control module, used to perform synchronous logic control operations according to the operating state and operating parameters, and generate the synchronous control instructions; An instruction output module, used for outputting the synchronous control instruction; The active power instruction includes a system active power instruction and a unit active power instruction; The reactive power instruction includes a system reactive power instruction and a unit reactive power instruction; The synchronous logic control operation includes: The system active power command and system reactive power command are calculated according to the following formula: Among them, P set_sys is the system active power command, Q set_sys is the system reactive power command, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, G u (s), G x (s) are the transfer functions of the active regulator and reactive regulator respectively; The unit active power command and unit reactive power command of each energy storage converter unit are calculated according to the following formula: Where i is the serial number of the energy storage converter unit, λ(i) is the operating state parameter value of the energy storage converter unit i, and P set (i) is the unit active power instruction of energy storage converter unit i, Q set (i) is the reactive power command of the energy storage converter unit i, j is the number of energy storage converter units in normal operation, j is an integer, j ≥ 2; S rate (i) is the rated capacity of energy storage converter unit i.

2. The synchronous control device according to claim 1, characterized in that: The operating status includes: The number of energy storage converter units that are operating normally, operating abnormally, and operating normally.

3. The synchronous control device according to claim 2, characterized in that: The operating parameters include: One or more of the energy storage system AC bus voltage, grid voltage, and common connection point switch position.

4. The synchronous control device according to claim 1, characterized in that: The active power regulator and reactive power regulator include: Integral regulator or proportional-integral regulator.

5. The synchronous control device according to claim 1, characterized in that: The concurrent instructions include: Synchronous instructions sent by external control system or localized synchronous instructions.

6. The synchronous control device according to claim 3, characterized in that: The synchronous control instruction also includes: An operating mode instruction sent to the energy storage converter unit; and / or A switch control instruction is sent to the common connection point switch.

7. A synchronization control method for a large-scale battery energy storage system, applied to the synchronization control device according to any one of claims 1 to 6, characterized in that: include: In the off-grid operation state, the central control unit obtains the synchronization instructions, the operation parameters of the energy storage system, and the operation state of the energy storage converter unit in the energy storage system in real time; After the synchronous instruction is set, the central control unit performs synchronous logic control operations according to the operating parameters and operating status to generate synchronous control instructions including active power instructions and reactive power instructions; The central control unit sends the generated active power instruction and reactive power instruction to the energy storage converter unit through hierarchical interaction; The active power instruction includes a system active power instruction and a unit active power instruction; The reactive power instruction includes a system reactive power instruction and a unit reactive power instruction; The synchronous logic control operation includes: The system active power command and system reactive power command are calculated according to the following formula: Among them, P set_sys is the system active power command, Q set_sys is the system reactive power command, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, G u (s), G x (s) are the transfer functions of the active regulator and reactive regulator respectively; The unit active power command and unit reactive power command of each energy storage converter unit are calculated according to the following formula: Where i is the serial number of the energy storage converter unit, λ(i) is the operating state parameter value of the energy storage converter unit i, and P set (i) is the unit active power instruction of energy storage converter unit i, Q set (i) is the reactive power command of the energy storage converter unit i, j is the number of energy storage converter units in normal operation, j is an integer, j ≥ 2; S rate (i) is the rated capacity of energy storage converter unit i.

8. The synchronization control method according to claim 7, characterized in that: The hierarchical interaction includes: The central control unit sends the active power instruction and reactive power instruction to the sub-control unit corresponding to the energy storage converter unit through the second information interaction network; The sub-control unit sends the active power instruction and the reactive power instruction to the energy storage conversion sub-unit through the first information interaction network.

9. The synchronous control method according to claim 7, characterized in that: The operating parameters include: One or more of the energy storage system AC bus voltage, grid voltage, and common connection point switch position.

10. The synchronization control method according to claim 9, characterized in that: The operating status includes: The number of energy storage converter units that are operating normally, operating abnormally, and operating normally.

11. The synchronous control method according to claim 7, characterized in that: The active power regulator and reactive power regulator include: Integral regulator or proportional-integral regulator.

12. The synchronization control method according to claim 9, characterized in that: Also includes: The obtained AC bus voltage of the energy storage system and the grid voltage are used to determine the synchronization completion status according to the following synchronization completion formula: Among them, u gq is the q-axis component of the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, X us , X ug are the voltage vector amplitudes of the AC bus voltage of the energy storage system and the grid voltage in the AC bus voltage rotation coordinate system of the energy storage system, u q_sync , X u_sync It is the preset value for judging the completion of the synchronization.

13. The synchronous control method according to claim 12, characterized in that: The simultaneous completion status judgment includes: When the AC bus voltage of the energy storage system and the grid voltage satisfy the synchronization completion formula, it is determined that the energy storage system enters the first synchronization completion state.

14. The synchronous control method according to claim 13, characterized in that: The concurrent completion status determination also includes: After entering the first state of synchronization completion, after a delay, when the AC bus voltage and the grid voltage of the energy storage system meet the synchronization completion formula, it is determined that the energy storage system enters the second state of synchronization completion.

15. The synchronization control method according to claim 14, characterized in that: The synchronous control instruction also includes: Operating mode commands and / or switch control commands.

16. The synchronization control method according to claim 15, characterized in that: Also includes: When the energy storage system enters the first state of synchronous completion or the second state of synchronous completion, the central control unit sends the switch control instruction to the common connection point switch.

17. The synchronization control method according to claim 16, characterized in that: Also includes: When the acquired common connection point switch position is closed, the central control unit sends the operation mode instruction to the energy storage converter subunit through the first information interaction network, the sub-control unit and the second information interaction network.

18. The synchronization control method according to claim 7, characterized in that: The concurrent instructions include: Synchronous instructions sent by external control system or localized synchronous instructions.

19. An electronic device, characterized in that: include: one or more processors; A storage device for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the synchronization control method as described in any one of claims 7-18.

20. A computer readable medium having a computer program stored thereon, characterized in that: When the program is executed by the processor, the synchronous control method as described in any one of claims 7 to 18 is implemented.

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