Discharge control method and system for energy storage system

Abstract

The invention relates to the technical field of energy storage systems, and provides an energy storage system discharge control method and system, and the method comprises the steps: obtaining emergency power supply duration and inverter discharge efficiency; after discharging is started in the peak period, the average discharging power in the discharging duration is obtained, the product of the average discharging power and the emergency power supply duration is calculated, and the ratio of the product of the average discharging power and the emergency power supply duration to the discharging efficiency of the inverter serves as the reserved battery electric quantity; comparing the battery remaining capacity with the reserved battery capacity in the peak period discharge period; stopping discharging when the residual electric quantity of the battery is reduced to the reserved electric quantity of the battery; and if the residual electric quantity of the battery is not reduced to the reserved electric quantity of the battery at the end of the peak discharge time, stopping discharging. Therefore, when the effective capacity of the energy storage system is fully utilized for peak shifting energy storage, reasonable power supply guarantee duration can be provided for important loads when the power grid is powered off, and better balance is obtained between economical efficiency and power supply reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage systems, and in particular relates to a discharge control method and system for an energy storage system. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] As user-side energy storage equipment, household and commercial energy storage systems can not only be connected to the grid and have the functions of timed charging and discharging to achieve peak shifting and valley filling to reduce user electricity expenses and grid demand, but also generally have the ability to operate off the grid. They can be used as emergency power supplies or uninterruptible power supplies to provide power supply guarantee for important loads in homes or industrial and commercial parks.

[0004] The emergency power supply function requires the energy storage system to continue to supply power to important loads by discharging energy storage batteries during power outages, while the peak-shifting energy storage function requires the system to discharge batteries during peak power consumption periods. Sometimes, there is a contradiction between the two: when the energy storage system discharges the battery during peak hours, if there happens to be a power outage in the grid, the battery will have no power to discharge, and the power supply guarantee function is out of the question.

[0005] To this end, the usual practice is to manually set a reserve power level. When discharging during peak hours, the battery is not fully discharged, but a certain amount of power is retained to ensure that power can be provided for important loads in the event of a subsequent power outage in the grid.

[0006] Although the conventional method of setting the reserved power (also known as the discharge cut-off power) can basically solve the problem of ensuring power supply when an unexpected power outage occurs after the peak period, it also has disadvantages: if the reserved capacity is set too large, the capacity that can be used for peak-shifting energy storage will be reduced accordingly, affecting the investment return of the equipment and causing waste; if the reserved capacity is set too small, the power outage protection capability will be weak, the protection time will be shortened, and it may lead to failure to protect important loads. Chinese patent CN115313456A also mentions setting the cut-off power of the energy storage battery, but does not propose how the cut-off power should be determined. It can be seen that the setting of the reserved power is often confusing to users. Obviously, it is often difficult for users to determine the appropriate reserved power by themselves. Summary of the invention

[0007] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides a discharge control method and system for an energy storage system, which automatically calculates the reserved battery power by analyzing the power consumption pattern of important loads during the discharge process during peak hours, thereby fully utilizing the effective capacity of the energy storage system for peak-shifting energy storage, while ensuring that a reasonable power supply guarantee duration can be provided for important loads when the power grid is out of power, thereby achieving a better balance between economy and power supply reliability.

[0008] In order to achieve the above object, the present invention adopts the following technical solution:

[0009] A first aspect of the present invention provides a method for controlling discharge of an energy storage system, comprising:

[0010] Obtain emergency power supply duration and inverter discharge efficiency;

[0011] After the discharge starts during the peak period, the average discharge power during the discharge duration is obtained, and the product of the average discharge power and the emergency power supply duration is calculated, and the ratio of the product of the two to the inverter discharge efficiency is used as the reserved battery power;

[0012] During the peak period of discharge, the remaining battery power is compared with the reserved battery power; when the remaining battery power is reduced to the reserved battery power, the discharging is stopped; if the remaining battery power has not been reduced to the reserved battery power at the end of the peak discharge time, the discharging is stopped.

[0013] Furthermore, the emergency power supply duration is the duration for maintaining the load on the local interface.

[0014] Furthermore, the average discharge power is a ratio of the accumulated discharge amount of the local interface to the discharge duration.

[0015] Furthermore, if the remaining battery power is greater than the reserved battery power and the peak discharge time has not ended, the reserved battery power is recalculated.

[0016] Furthermore, if the remaining battery power has not decreased to the reserved battery power at the end of the peak discharge time, and after the discharge stops, if the next period is a valley period, the charging state is entered.

[0017] Furthermore, if the remaining battery power has not been reduced to the reserved battery power at the end of the peak discharge time, and after the discharge stops, if the next time period is a normal time period, the system enters the standby state.

[0018] Furthermore, during the peak-hour discharge, if the grid fails, the discharge state is maintained.

[0019] A second aspect of the present invention provides an energy storage system discharge control system, comprising:

[0020] A data acquisition module is configured to: acquire emergency power supply duration and inverter discharge efficiency;

[0021] A reserved battery power calculation module is configured to: after the discharge starts during the peak period, obtain the average discharge power during the discharge duration, calculate the product of the average discharge power and the emergency power supply duration, and use the ratio of the product of the two to the inverter discharge efficiency as the reserved battery power;

[0022] The discharge control module is configured to: compare the remaining battery power with the reserved battery power during peak discharge; stop discharging when the remaining battery power drops to the reserved battery power; and stop discharging if the remaining battery power has not dropped to the reserved battery power at the end of the peak discharge time.

[0023] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-mentioned method for controlling discharge of an energy storage system.

[0024] A fourth aspect of the present invention provides a computer device, comprising a computer-readable storage medium, a processor, and a computer program stored on the computer-readable storage medium and executable on the processor, wherein when the processor executes the program, the steps in the energy storage system discharge control method as described above are implemented.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention automatically calculates the reserved battery power by analyzing the power consumption patterns of important loads during the discharge process during peak hours, thereby fully utilizing the effective capacity of the energy storage system for peak-shifting energy storage while ensuring that a reasonable power supply guarantee duration can be provided to important loads when the power grid is out, thereby achieving a better balance between economy and power supply reliability.

[0027] The manual setting of the emergency power supply duration according to the present invention is easier for users to understand and master than the manual setting of the reserved battery capacity, which helps to significantly improve the usability of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 is a flow chart of a method for discharging control of an energy storage system according to the first embodiment of the present invention;

[0030] Figure 2 is a structural diagram of an energy storage system according to Embodiment 1 of the present invention;

[0031] Figure 3 It is a structural diagram of a computer device according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0032] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0033] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] Terminology explanation:

[0035] The peak and valley time periods of the power grid are usually divided into peak hours, normal hours and valley hours. The specific time division is determined by the power supply department based on the local power consumption and power supply conditions. It varies from region to region. The following are common peak and valley time divisions:

[0036] Peak hours: generally from 10:00 to 12:00 in the morning and from 15:00 to 20:00 in the evening. During this period, the demand for electricity is high. In order to curb electricity consumption, the electricity price during peak hours will be set higher than that during normal hours;

[0037] Off-peak hours: generally from 0:00 am to 7:00 am. During this period, the demand for electricity is lower. In order to encourage users to use electricity during this period, the electricity price during the off-peak period will be set lower than that during normal times.

[0038] Normal period: Electricity prices return to normal during periods other than peak and off-peak periods.

[0039] Embodiment 1

[0040] This embodiment provides a method for controlling discharge of an energy storage system.

[0041] like Figure 2 As shown, the user-side energy storage system for home or commercial use is usually equipped with two AC interfaces: one is used to connect to the AC grid to achieve normal charge and discharge cycles; the other is used to connect important loads to provide uninterrupted guaranteed power supply capabilities for the electrical equipment connected to the interface. For the convenience of description, this embodiment is referred to as the grid interface and the local interface respectively. Important loads are connected to the local interface, and general loads are directly connected to the grid interface.

[0042] The present embodiment provides a method for controlling the discharge of an energy storage system. By analyzing the power consumption patterns of important loads during the discharge process during peak hours, the reserved capacity is automatically calculated. This ensures that a reasonable power supply duration can be provided to important loads when the power grid is out of power, while fully utilizing the effective capacity of the energy storage system for peak-shifting energy storage. This achieves a better balance between economy and power supply reliability.

[0043] Energy storage systems usually set up reasonable charging and discharging strategies based on the local power grid’s time-of-use electricity price list:

[0044] (1) The battery is charged through the grid interface during off-peak hours, and is in standby mode during normal hours;

[0045] (2) Discharge simultaneously through the grid interface and the local power interface during peak hours;

[0046] (3) Set appropriate grid-connected discharge power and discharge duration to ensure that the energy storage system is used as much as possible during peak hours to reduce the use of grid power by households or industrial and commercial parks, thereby reducing electricity costs;

[0047] (4) When the external power grid fails, the grid isolation switch is disconnected, and the energy storage system continues to supply power to important loads through the local interface without discharging to the grid;

[0048] (5) During the discharge period, a discharge cut-off power is set. When the remaining power of the battery is lower than the discharge cut-off power, the discharge is stopped to avoid over-discharge of the battery.

[0049] On this basis, this embodiment provides a method for controlling the discharge of an energy storage system, such as Figure 1 As shown, the main steps are as follows:

[0050] Step 1: Set the emergency power supply duration parameters.

[0051] The emergency power supply duration parameter is set by the user based on the duration for which the important loads on the local interface need to be maintained during a power outage, so as to minimize the probability of important equipment stopping working due to a power outage.

[0052] The emergency power supply duration is a preset parameter, and its value is usually based on the local power supply reliability and the importance of the load as the main considerations. Reasonable duration setting can ensure that important loads can be powered when the power grid is out in most cases.

[0053] Step 2: After the discharge starts during the peak period, monitor and continuously record the output power of the local interface (i.e., monitor the emergency output interface power) and the amount of electricity discharged by the local interface (i.e., the accumulated emergency output electricity, also known as the accumulated discharge amount); and monitor the actual remaining battery power.

[0054] In this embodiment, the electric quantity refers to electric energy, with the unit of Wh or Ws. According to the definition of electricity, the electric energy is equal to the integral of the electric power in a specified time period, and is usually calculated by numerical integration method.

[0055] Step 3: Periodically and continuously calculate the average discharge power during the discharge period (i.e., the average emergency output power), and the calculation formula is as follows:

[0056] Average discharge power = cumulative discharge amount / discharge duration.

[0057] Step 4: Periodically calculate the battery power that needs to be reserved (i.e., retain the battery power), the formula is as follows:

[0058] Reserved battery power (6) = average discharge power (4) × emergency power supply duration (1) / inverter discharge efficiency (7).

[0059] Step 5: During the peak period of discharge, the actual remaining battery power (8) is continuously compared with the reserved battery power (6) parameter obtained in step 4; when the remaining battery power (8) is reduced to the reserved battery power (6), the peak discharge is stopped and the system enters the standby state; when the remaining battery power (8) is greater than the reserved battery power (6), it is determined whether the peak period has ended; if the remaining battery power (8) is greater than the reserved battery power (6) and the peak period has not ended, the system returns to step 2; if the remaining battery power has not yet been reduced to the calculated reserved battery power at the end of the preset peak discharge time, the discharge is stopped as planned, and if the next period is a valley period, the system enters the charging state; if the next period is a flat period, the system enters the standby state.

[0060] Step 6: If the power grid is out of power during the peak discharge period, the discharge state is maintained. If the power grid is restored during the peak discharge period, the process returns to step 2 to continue calculating the reserved power and comparing the remaining battery power to determine whether the discharge needs to be stopped.

[0061] During the off-peak charging period, the energy storage system is in a charging state. If the power grid goes out at this time, the actual remaining battery power will gradually decrease. During the normal standby period, the energy storage system is in a standby state. If the power grid goes out at this time, the battery also needs to be discharged, and the battery power will gradually decrease from the full state. In these two stages, there is no need to calculate the reserved battery power.

[0062] After entering the peak discharge state, the above steps are performed periodically until the discharge termination condition is met. The calculation repetition period can be selected between several seconds and tens of seconds according to the computing power of the device.

[0063] By adding the above operations to the energy storage system's charging and discharging control strategy, the battery power can be reserved more reasonably, thereby achieving a better balance between the energy storage system's operating economy and the reliability of power supply to important loads.

[0064] The energy storage system discharge control method provided in this embodiment can also be used for an energy storage system with photovoltaic input. The photovoltaic input only affects the rate of decrease of the remaining power of the battery and does not affect the calculation of the reserved power.

[0065] The present embodiment provides a method for controlling the discharge of an energy storage system. Based on the traditional method for controlling the discharge of an energy storage system, the energy storage power supply system automatically and dynamically determines the battery reserved power reasonably by calculating the power consumption characteristics of important loads, thereby making full use of the capacity of the energy storage battery for peak-valley arbitrage, improving economic efficiency, and effectively reducing the probability of power outages of important loads.

[0066] The concept of duration is easy for ordinary people to understand intuitively, but the size of the battery capacity is often not intuitive to most people. Therefore, manually setting the emergency power supply duration is easier for users to understand and master than manually setting the reserved battery capacity, which helps to significantly improve the usability of the equipment.

[0067] Embodiment 2

[0068] This embodiment provides an energy storage system discharge control system, which specifically includes:

[0069] A data acquisition module is configured to: acquire emergency power supply duration and inverter discharge efficiency;

[0070] A reserved battery power calculation module is configured to: after the discharge starts during the peak period, obtain the average discharge power during the discharge duration, calculate the product of the average discharge power and the emergency power supply duration, and use the ratio of the product of the two to the inverter discharge efficiency as the reserved battery power;

[0071] The discharge control module is configured to: compare the remaining battery power with the reserved battery power during peak discharge; stop discharging when the remaining battery power drops to the reserved battery power; and stop discharging if the remaining battery power has not dropped to the reserved battery power at the end of the peak discharge time.

[0072] It should be noted here that each module in this embodiment corresponds to each step in Example 1 one by one, and the specific implementation process is the same, which will not be repeated here.

[0073] Embodiment 3

[0074] This embodiment provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, the steps in the energy storage system discharge control method described in the first embodiment are implemented.

[0075] Embodiment 4

[0076] This embodiment provides a computer device, such as Figure 3As shown, it includes a computer-readable storage medium 1003, a processor 1001, a communication interface 1002, and a computer program stored on the computer-readable storage medium 1003 and executable on the processor 1001, wherein the processor 1001, the communication interface 1002, and the computer-readable storage medium 1003 can be connected via a bus or other means. The communication interface 1002 is used to receive and send data, and when the processor 1001 executes the program, the steps in the energy storage system discharge control method described in the first embodiment are implemented.

[0077] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to form a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling discharge of an energy storage system, characterized in that: include: Obtain emergency power supply duration and inverter discharge efficiency; After the discharge starts during the peak period, the average discharge power during the discharge duration is obtained, and the product of the average discharge power and the emergency power supply duration is calculated, and the ratio of the product of the two to the inverter discharge efficiency is used as the reserved battery power; During the peak period of discharge, the remaining battery power is compared with the reserved battery power; when the remaining battery power is reduced to the reserved battery power, the discharging is stopped; if the remaining battery power has not been reduced to the reserved battery power at the end of the peak discharge time, the discharging is stopped.

2. A method for controlling discharge of an energy storage system according to claim 1, characterized in that: The emergency power supply duration is the duration for maintaining the load on the local interface.

3. The energy storage system discharge control method according to claim 1, characterized in that: The average discharge power is the ratio of the accumulated discharge amount of the local interface to the discharge duration.

4. The energy storage system discharge control method according to claim 1, characterized in that: If the remaining battery power is greater than the reserved battery power and the peak discharge time has not ended, return to recalculate the reserved battery power.

5. The energy storage system discharge control method according to claim 1, characterized in that: If at the end of the peak discharge time, the remaining battery power has not dropped to the reserved battery power, and after the discharge stops, if the next period is a valley period, the charging state will be entered.

6. The energy storage system discharge control method according to claim 1, characterized in that: If the remaining battery power has not dropped to the reserved battery power at the end of the peak discharge time, and after the discharge stops, if the next period is a normal period, the system will enter the standby state.

7. The energy storage system discharge control method according to claim 1, characterized in that: During the peak period of discharge, if the power grid fails, the discharge state will continue to be maintained.

8. A discharge control system for an energy storage system, characterized in that: include: A data acquisition module is configured to: acquire emergency power supply duration and inverter discharge efficiency; A reserved battery power calculation module is configured to: after the discharge starts during the peak period, obtain the average discharge power during the discharge duration, calculate the product of the average discharge power and the emergency power supply duration, and use the ratio of the product of the two to the inverter discharge efficiency as the reserved battery power; The discharge control module is configured to: compare the remaining battery power with the reserved battery power during peak discharge; stop discharging when the remaining battery power drops to the reserved battery power; and stop discharging if the remaining battery power has not dropped to the reserved battery power at the end of the peak discharge time.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps in a method for controlling discharge of an energy storage system as described in any one of claims 1 to 7 are implemented.

10. A computer device comprising a computer-readable storage medium, a processor, and a computer program stored in the computer-readable storage medium and executable on the processor, characterized in that: When the processor executes the program, the steps in the energy storage system discharge control method according to any one of claims 1 to 7 are implemented.

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