User side energy storage system and control method thereof

Abstract

The invention provides a user side energy storage system and a control method thereof, and belongs to the technical field of electrochemical energy storage, the user side energy storage system comprises an energy storage converter and a battery, a first end of the energy storage converter is connected with the battery, and a second end of the energy storage converter is connected with a power grid side through a circuit breaker QF0; the power grid state detection module comprises a first intermediate relay and a second intermediate relay which are connected in parallel to the alternating current grid-connected switch power grid side of the user-side energy storage system, a coil of the first intermediate relay is in bridge connection with an A phase and an N phase, and a coil of the second intermediate relay is in bridge connection with a B phase and a C phase; normally open auxiliary contacts of the first intermediate relay and the second intermediate relay are used as input signals for judging the state of the power grid, and the input signals are accessed to an energy management system; and the energy management system is connected with the energy storage converter. And one-key startup and shutdown operation can be realized without opening a door.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, and particularly relates to a user-side energy storage system and its control method. Background Technology

[0002] Traditional user-side energy storage systems integrate power distribution systems, lithium iron phosphate batteries, battery management systems (BMS), energy management systems (EMS), thermal management systems, fire protection systems, and energy storage converters (PCS) into a single outdoor cabinet or container.

[0003] When starting the user-side energy storage system, the control power supply must first be started using an uninterruptible power supply (UPS) to power the battery management system (BMS) and energy management system (EMS). After the BMS and EMS are started, the user needs to select the operating mode such as grid-connected charging, grid-connected discharging, or off-grid operation as needed, and click the corresponding operation button on the EMS human-machine interface (host computer or touch screen) to start the energy storage system.

[0004] Traditional user-side energy storage systems involve cumbersome control methods, and improper operation can lead to malfunctions in energy storage devices or loads. Since the UPS and EMS HMIs are often located in different parts of the energy storage system, users must open the system cabinet door (or hatch) to operate the UPS during startup and shutdown, making the process complex. Furthermore, if the energy storage system is connected to the grid, a user's mistaken issuance of an off-grid command can cause a conflict between the PCS output AC voltage and the grid voltage, potentially resulting in a large current output from the PCS, damaging the load or the PCS module. Summary of the Invention

[0005] This invention provides a user-side energy storage system and its control method, aiming to reduce the complexity of the energy storage system, enable one-button start-up and shutdown without opening the door, and allow the energy storage system to automatically determine and operate off-grid status, thus avoiding user misoperation.

[0006] In a first aspect, embodiments of this application provide a user-side energy storage system, which includes an energy storage converter and a battery. The first end of the energy storage converter is connected to the battery, and the second end of the energy storage converter is connected to the grid side through a circuit breaker QF0. The energy storage converter is also connected to an energy management system. The user-side energy storage system also includes: The power grid status detection module includes a first intermediate relay and a second intermediate relay connected in parallel to the grid side of the AC grid-connected switch of the user-side energy storage system. The coil of the first intermediate relay is connected across phase A and phase N, and the coil of the second intermediate relay is connected across phase B and phase C. The normally open auxiliary contacts of the first and second intermediate relays serve as input signals for judging the power grid status, and these input signals are connected to the energy management system.

[0007] Furthermore, the first intermediate relay is a 220V intermediate relay; The second intermediate relay is a 380V intermediate relay; Both the first intermediate relay and the second intermediate relay are intermediate relays with one set of normally open auxiliary contacts and one set of normally closed auxiliary contacts.

[0008] Furthermore, the user-side energy storage system also includes an external operation module, which is located on the outside of the user-side energy storage system cabinet door; The external operation module includes a UPS start button and a UPS stop button; The normally open auxiliary contact of the UPS start button is connected to the UPS start terminal of the uninterruptible power supply, and the normally open auxiliary contact of the UPS stop button is connected to the stop input terminal of the uninterruptible power supply. The external operation module also includes a stop button. The normally open auxiliary contact of the stop button serves as an input signal for stopping the control system, and this input signal is connected to the energy management system.

[0009] Furthermore, the user-side energy storage system cabinet door is also equipped with a UPS indicator light on the outside to indicate the operating status of the UPS. The UPS output port of the uninterruptible power supply is connected to the power port of the indicator light to supply power to the indicator light.

[0010] Secondly, embodiments of this application also provide a control method applied to a user-side energy storage system as described in the above aspects, the control method comprising the following steps: Step S1: The energy management system acquires the operating status data of the energy storage converter. If a fault exists, the process is terminated; if there is no fault, step S2 is executed. Step S2: The energy management system determines the grid status based on the first input signal and the second input signal; when both the first input signal and the second input signal are valid, it is in grid-connected status; when both the first input signal and the second input signal are invalid, it is in off-grid status; when only one of the first input signal and the second input signal is valid, it is in phase loss status. Step S3: When the grid-connected state continues for a preset duration, the energy management system sends a grid-connected start-up command to the energy storage converter; when the off-grid state continues for a preset duration, the energy management system sends an off-grid start-up command to the energy storage converter.

[0011] Furthermore, before the energy management system obtains the operating status data of the energy storage converter, it also includes: triggering the uninterruptible power supply by pressing the UPS start button outside the cabinet door, and confirming successful startup by the UPS indicator light illuminating.

[0012] Furthermore, the control method further includes: Step S4: After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and sends charging / discharging commands to the energy storage converter based on the battery SOC value.

[0013] Further, in step S4: After the energy storage converter executes the grid-connected start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and issues charging / discharging commands to the energy storage converter based on the battery SOC value, specifically including: When the battery state of charge (SOC) uploaded by the battery management system is less than 10%, the energy management system sends a grid-connected charging command to the energy storage converter, and the energy storage converter performs grid-connected charging at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is greater than 90%, the energy management system sends a grid-connected discharge command to the energy storage converter, and the energy storage converter discharges to the grid at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is 10% ≤ SOC ≤ 90%, the energy management system will display a dialog box on the human-machine interface to select between grid-connected charging and grid-connected discharging. Users can click the grid-connected charging or grid-connected discharging button to complete the charging and discharging selection according to their actual needs.

[0014] Further, in step S4: after the energy storage converter executes the grid-connected start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and issues charging / discharging commands to the energy storage converter based on the battery SOC value. It also includes: after the energy storage converter executes the off-grid start-up command issued by the energy management system, it automatically operates in V / f working mode.

[0015] Furthermore, the control method further includes: Step S5: Trigger the shutdown button to generate the third input quantity, the energy management system sends a shutdown command to the energy storage converter, and press the UPS stop button to shut off the uninterruptible power supply.

[0016] As can be seen from the above technical solutions, the present invention has the following advantages: The user-side energy storage system provided in this application reduces the complexity of energy storage system operation, enabling one-button start-up and shutdown without opening the door. The energy storage system automatically performs grid-connected / off-grid operation and charging / discharging operations according to the grid status, which simplifies user operation and avoids the risk of equipment failure caused by user misoperation. Attached Figure Description

[0017] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a circuit diagram of a user-side energy storage system according to the present invention.

[0019] Figure 2 This is a circuit pin diagram of the energy management system in a user-side energy storage system according to the present invention. Detailed Implementation

[0020] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this patent, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this patent.

[0021] The technical solutions proposed in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0022] Figure 1 This is a circuit diagram of a user-side energy storage system provided in an embodiment of this application. Figure 1 As shown in the embodiment of this application, a user-side energy storage system is provided. The user-side energy storage system includes an energy storage converter and a battery. The first end of the energy storage converter is connected to the battery, and the second end of the energy storage converter is connected to the grid side through a circuit breaker QF0. The user-side energy storage system also includes an uninterruptible power supply (UPS) and a battery management system (BMS), both of which are connected to the energy management system. The energy storage converter is also connected to the energy management system.

[0023] The user-side energy storage system also includes: The power grid status detection module includes a first intermediate relay and a second intermediate relay connected in parallel to the grid side of the AC grid-connected switch of the user-side energy storage system. The coil of the first intermediate relay is connected across phase A and phase N, and the coil of the second intermediate relay is connected across phase B and phase C. The normally open auxiliary contacts of the first and second intermediate relays serve as input signals for judging the power grid status, and these input signals are connected to the energy management system.

[0024] This invention reduces the complexity of operating energy storage systems, enabling one-button start-up and shutdown without opening the door. The energy storage system automatically performs grid-connected / off-grid operation and charging / discharging operations according to the grid status. While simplifying user operation, it can avoid the risk of equipment failure caused by user misoperation (issuing off-grid operation commands when the energy storage system is in grid-connected state).

[0025] In one exemplary embodiment, the first intermediate relay is a 220V intermediate relay; the second intermediate relay is a 380V intermediate relay; both the first and second intermediate relays are intermediate relays having one set of normally open auxiliary contacts and one set of normally closed auxiliary contacts.

[0026] According to another embodiment of the present invention, the user-side energy storage system further includes an external operation module, which is disposed on the outside of the user-side energy storage system cabinet door; The external operation module includes a UPS start button and a UPS stop button; The normally open auxiliary contact of the UPS start button is connected to the UPS start terminal of the uninterruptible power supply (UPS), and the normally open auxiliary contact of the UPS stop button is connected to the stop input terminal of the uninterruptible power supply (UPS). The external operation module also includes a stop button. The normally open auxiliary contact of the stop button serves as an input signal for stopping the control system, and this input signal is connected to the energy management system.

[0027] The normally open auxiliary contact of the first intermediate relay is defined as the first input, the normally open auxiliary contact of the second intermediate relay is defined as the second input, and the stop button signal is defined as the third input. The first, second, and third inputs are all connected to the energy management system.

[0028] According to an embodiment of this application, the user-side energy storage system cabinet door is also provided with a UPS indicator light on the outside to indicate the operating status of the UPS. The UPS output port of the uninterruptible power supply is connected to the power port of the indicator light to supply power to the indicator light.

[0029] The present invention also provides a control method for a user-side energy storage system as described in the above embodiments, the control method comprising the following steps: Step S1: The Energy Management System (EMS) acquires the operating status data of the Energy Storage Converter (PCS). If a fault exists, the process is terminated; if there is no fault, step S2 is executed.

[0030] It should be noted that after the UPS starts, the PCS, BMS, EMS, and fire protection systems in the energy storage system will have working power. The energy management system (EMS) reads fault information from other devices through the communication loop and displays the fault information on the human-machine interface. When the energy management system (EMS) detects a fault, it will not proceed to the next step; when the EMS detects no fault, it will execute step S2.

[0031] Step S2: The energy management system determines the grid status based on the first input signal and the second input signal; when both the first input signal and the second input signal are valid, it is in grid-connected status; when both the first input signal and the second input signal are invalid, it is in off-grid status; when only one of the first input signal and the second input signal is valid, it is in phase loss status.

[0032] Specifically, the normally open auxiliary contacts of the 220V and 380V intermediate relays are defined as the first input and the second input, respectively. When the grid connection point voltage of the user-side energy storage system is normal, both the first and second inputs are valid, and the Energy Management System (EMS) defines this as "grid-connected state". When the grid connection point voltage of the user-side energy storage system is 0, the two intermediate relay coils will not engage due to the lack of voltage, and neither the first nor the second input will be active. The EMS defines this as "off-grid state". When only one of the first or the second input is active, the EMS determines that this is a "phase loss state" of the power grid.

[0033] Step S3: When the grid-connected state continues for a preset duration of 2 seconds, the energy management system sends a grid-connected start-up command to the energy storage converter; when the off-grid state continues for a preset duration of 2 seconds, the energy management system sends an off-grid start-up command to the energy storage converter.

[0034] According to an embodiment of this application, before the energy management system (EMS) acquires the operating status data of the energy storage converter (PCS), it further includes: triggering the uninterruptible power supply (UPS) to supply power by pressing the UPS start button outside the cabinet door, and confirming successful start by the UPS indicator light illuminating.

[0035] Pressing the UPS start button for 2-3 seconds triggers the UPS to start, and the UPS indicator light illuminates to indicate successful startup.

[0036] In one embodiment, the control method includes the following specific steps: Step S1: The Energy Management System (EMS) acquires the operating status data of the Energy Storage Converter (PCS). If a fault exists, the process is terminated; if there is no fault, step S2 is executed.

[0037] Step S2: The energy management system determines the grid status based on the first input signal and the second input signal; when both the first input signal and the second input signal are valid, it is in grid-connected status; when both the first input signal and the second input signal are invalid, it is in off-grid status; when only one of the first input signal and the second input signal is valid, it is in phase loss status.

[0038] Step S3: When the grid-connected state continues for a preset duration of 2 seconds, the energy management system sends a grid-connected start-up command to the energy storage converter; when the off-grid state continues for a preset duration of 2 seconds, the energy management system sends an off-grid start-up command to the energy storage converter.

[0039] Step S4: After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system (BMS) through the BMS communication port, and sends charging / discharging commands to the energy storage converter based on the battery SOC value.

[0040] In one embodiment, step S4: After the energy storage converter executes the grid-connected start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system (BMS) through the BMS communication port, and issues charging / discharging commands to the energy storage converter based on the battery SOC value, specifically including: When the battery state of charge (SOC) uploaded by the battery management system is less than 10%, the energy management system sends a grid-connected charging command to the energy storage converter, and the energy storage converter performs grid-connected charging at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is greater than 90%, the energy management system sends a grid-connected discharge command to the energy storage converter, and the energy storage converter discharges to the grid at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is 10% ≤ SOC ≤ 90%, the energy management system will display a dialog box on the human-machine interface to select between grid-connected charging and grid-connected discharging. Users can click the grid-connected charging or grid-connected discharging button to complete the charging and discharging selection according to their actual needs.

[0041] As an example, step S4: After the energy storage converter executes the grid-connected start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system (BMS) through the BMS communication port, and issues charging / discharging commands to the energy storage converter based on the battery SOC value. It also includes: After the energy storage converter executes the off-grid start-up command issued by the energy management system, it automatically operates in V / f working mode.

[0042] According to an embodiment of this application, the control method further includes: Step S1: The Energy Management System (EMS) acquires the operating status data of the Energy Storage Converter (PCS). If a fault exists, the process is terminated; if there is no fault, step S2 is executed.

[0043] It should be noted that after the UPS starts, the PCS, BMS, EMS, and fire protection systems in the energy storage system will have working power. The energy management system (EMS) reads fault information from other devices through the communication loop and displays the fault information on the human-machine interface. When the energy management system (EMS) detects a fault, it will not proceed to the next step; when the EMS detects no fault, it will execute step S2.

[0044] Step S2: The energy management system determines the grid status based on the first input signal and the second input signal; when both the first input signal and the second input signal are valid, it is in grid-connected status; when both the first input signal and the second input signal are invalid, it is in off-grid status; when only one of the first input signal and the second input signal is valid, it is in phase loss status.

[0045] Specifically, the normally open auxiliary contacts of the 220V and 380V intermediate relays are defined as the first input and the second input, respectively. When the grid connection point voltage of the user-side energy storage system is normal, both the first and second inputs are valid, and the Energy Management System (EMS) defines this as "grid-connected state". When the grid connection point voltage of the user-side energy storage system is 0, the two intermediate relay coils will not engage due to the lack of voltage, and neither the first nor the second input will be active. The EMS defines this as "off-grid state". When only one of the first or the second input is active, the EMS determines that this is a "phase loss state" of the power grid.

[0046] Step S3: When the grid-connected state continues for a preset duration of 2 seconds, the energy management system sends a grid-connected start-up command to the energy storage converter; when the off-grid state continues for a preset duration of 2 seconds, the energy management system sends an off-grid start-up command to the energy storage converter.

[0047] According to an embodiment of this application, before the energy management system (EMS) acquires the operating status data of the energy storage converter (PCS), it further includes: triggering the uninterruptible power supply (UPS) to supply power by pressing the UPS start button outside the cabinet door, and confirming successful start by the UPS indicator light illuminating.

[0048] Pressing the UPS start button for 2-3 seconds triggers the UPS to start, and the UPS indicator light illuminates to indicate successful startup.

[0049] Step S4: After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system (BMS) through the BMS communication port, and sends charging / discharging commands to the energy storage converter based on the battery SOC value.

[0050] After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system (BMS) through the BMS communication port. Based on the battery SOC value, it issues charging / discharging commands to the energy storage converter, specifically including: When the battery state of charge (SOC) uploaded by the battery management system is less than 10%, the energy management system sends a grid-connected charging command to the energy storage converter, and the energy storage converter performs grid-connected charging at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is greater than 90%, the energy management system sends a grid-connected discharge command to the energy storage converter, and the energy storage converter discharges to the grid at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is 10% ≤ SOC ≤ 90%, the energy management system will display a dialog box on the human-machine interface to select between grid-connected charging and grid-connected discharging. Users can click the grid-connected charging or grid-connected discharging button to complete the charging and discharging selection according to their actual needs.

[0051] Step S5: Trigger the shutdown button to generate the third input quantity, the energy management system sends a shutdown command to the energy storage converter, and press the UPS stop button to shut off the uninterruptible power supply.

[0052] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0053] For those skilled in the art, designing different forms of control circuits according to the teachings of this invention does not require creative effort. Changes, modifications, substitutions, and variations made to the embodiments without departing from the principles and spirit of this invention still fall within the scope of protection of this invention.

Claims

1. A user-side energy storage system, characterized in that, The user-side energy storage system includes an energy storage converter and a battery. The first end of the energy storage converter is connected to the battery, and the second end of the energy storage converter is connected to the grid side through a circuit breaker QF0. The energy storage converter is also connected to the energy management system. The user-side energy storage system also includes: The power grid status detection module includes a first intermediate relay and a second intermediate relay connected in parallel to the grid side of the AC grid-connected switch of the user-side energy storage system. The coil of the first intermediate relay is connected across phase A and phase N, and the coil of the second intermediate relay is connected across phase B and phase C. The normally open auxiliary contacts of the first and second intermediate relays serve as input signals for judging the power grid status, and these input signals are connected to the energy management system.

2. The user-side energy storage system as described in claim 1, characterized in that, The first intermediate relay is a 220V intermediate relay; The second intermediate relay is a 380V intermediate relay; Both the first intermediate relay and the second intermediate relay are intermediate relays with one set of normally open auxiliary contacts and one set of normally closed auxiliary contacts.

3. The user-side energy storage system as described in claim 2, characterized in that, The user-side energy storage system also includes an external operation module, which is located on the outside of the cabinet door of the user-side energy storage system. The external operation module includes a UPS start button and a UPS stop button; The normally open auxiliary contact of the UPS start button is connected to the UPS start terminal of the uninterruptible power supply, and the normally open auxiliary contact of the UPS stop button is connected to the stop input terminal of the uninterruptible power supply. The external operation module also includes a stop button. The normally open auxiliary contact of the stop button serves as an input signal for stopping the control system, and this input signal is connected to the energy management system.

4. The user-side energy storage system as described in claim 3, characterized in that, The user-side energy storage system cabinet is also equipped with a UPS indicator light on the outside of the cabinet door to indicate the operating status of the UPS. The UPS output port of the uninterruptible power supply is connected to the power port of the indicator light to supply power to the indicator light.

5. A control method applied to a user-side energy storage system as described in any one of claims 1-4, characterized in that, The control method includes the following steps: Step S1: The energy management system acquires the operating status data of the energy storage converter. If a fault exists, the process is terminated; if there is no fault, step S2 is executed. Step S2: The energy management system determines the grid status based on the first input signal and the second input signal; when both the first input signal and the second input signal are valid, it is in grid-connected status; when both the first input signal and the second input signal are invalid, it is in off-grid status; when only one of the first input signal and the second input signal is valid, it is in phase loss status. Step S3: When the grid-connected state continues for a preset duration, the energy management system sends a grid-connected start-up command to the energy storage converter; when the off-grid state continues for a preset duration, the energy management system sends an off-grid start-up command to the energy storage converter.

6. The control method as described in claim 5, characterized in that, Before the energy management system obtains the operating status data of the energy storage converter, it also includes: triggering the uninterruptible power supply by pressing the UPS start button outside the cabinet door, and confirming successful start by the UPS indicator light illuminating.

7. The control method as described in claim 6, characterized in that, The control method further includes: Step S4: After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and sends charging / discharging commands to the energy storage converter based on the battery SOC value.

8. The control method as described in claim 7, characterized in that, Step S4: After the energy storage converter executes the grid connection start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and issues charging / discharging commands to the energy storage converter based on the battery SOC value, specifically including: When the battery state of charge (SOC) uploaded by the battery management system is less than 10%, the energy management system sends a grid-connected charging command to the energy storage converter, and the energy storage converter performs grid-connected charging at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is greater than 90%, the energy management system sends a grid-connected discharge command to the energy storage converter, and the energy storage converter discharges to the grid at the existing power. When the battery state of charge (SOC) uploaded by the battery management system is 10% ≤ SOC ≤ 90%, the energy management system will display a dialog box on the human-machine interface to select between grid-connected charging and grid-connected discharging. Users can click the grid-connected charging or grid-connected discharging button to complete the charging and discharging selection according to their actual needs.

9. The control method as described in claim 8, characterized in that, Step S4: After the energy storage converter executes the grid-connected start-up command, the energy management system receives the battery state of charge (SOC) value uploaded by the battery management system through the BMS communication port, and sends charging / discharging commands to the energy storage converter based on the battery SOC value. It also includes: after the energy storage converter executes the off-grid start-up command issued by the energy management system, it automatically operates in V / f working mode.

10. The control method as described in claim 9, characterized in that, The control method further includes: Step S5: Trigger the shutdown button to generate the third input quantity, the energy management system sends a shutdown command to the energy storage converter, and press the UPS stop button to shut off the uninterruptible power supply.

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