Battery side insulation monitoring method of energy storage system and energy storage battery management system

Abstract

The invention relates to an energy storage system battery side insulation monitoring method and an energy storage battery management system.The energy storage system comprises at least one battery pack, the battery packs are mutually connected to form an energy storage battery unit, and the energy storage battery unit is connected with a post-stage circuit through a direct-current bus. The current in the energy storage battery unit is detected to obtain a first current, the current of the direct current bus is detected to obtain a second current, and based on the difference quantity of the first current and the second current, the current of the energy storage battery unit is obtained; judging whether the energy storage current side has an insulation fault or not; and if the difference between the first current and the second current is greater than a set threshold value, determining that the energy storage current side has the insulation fault. The real-time detection capability of the battery side of the energy storage system can be improved, the response speed is high, and the insulation protection effect on the battery side is better.

Description

Technical Field

[0001] This invention relates to the field of energy storage equipment control technology, specifically to a battery-side insulation monitoring method and an energy storage battery management system. Background Technology

[0002] Energy storage systems typically consist of storage batteries and inverters. Insulation checks on the battery side are usually performed by the Battery Management Unit (BMS). When insulation deteriorates, the BMS is responsible for taking appropriate protective actions to ensure the safe operation of the energy storage system. However, most existing insulation detection schemes only detect the DC side insulation. After the battery cluster is connected to the mains power, the impedance of the AC line to the PE side is relatively low, especially in non-isolated systems, which can affect the insulation detection on the battery side, rendering the insulation detection unable to perform its intended function.

[0003] Currently, insulation testing on the battery side cannot be performed online after the battery-side power storage converter (PCS) is connected to the grid. Even if testing is possible, it suffers from drawbacks such as poor accuracy and slow processing time. When insulation failure or short circuit occurs on the battery-side bus, the BMS can only detect it after the AC leakage protection switch trips, meaning the battery-side BMS cannot provide immediate and rapid protection. Summary of the Invention

[0004] A primary objective of this invention is to overcome at least one of the aforementioned deficiencies by providing a battery-side insulation monitoring method and a battery management system for energy storage systems, which can improve the real-time detection capability of the battery side of the energy storage system, have a fast response speed, and provide better insulation protection for the battery side.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for monitoring insulation on the battery side of an energy storage system. The energy storage system includes at least one battery pack, and the battery packs are interconnected to form an energy storage battery unit. The energy storage battery unit is connected to a subsequent circuit via a DC bus. The method involves detecting the current in the energy storage battery unit to obtain a first current, detecting the current in the DC bus to obtain a second current, and determining whether there is an insulation fault on the energy storage current side based on the difference between the first current and the second current.

[0006] According to one embodiment of the present invention, the amount based on the difference between the first current and the second current includes: The first current and the second current are integrated over time to convert them into a first accumulated charge over a preset time period. With the second accumulated power Based on the first accumulated power With the second accumulated power Obtain the difference.

[0007] According to one embodiment of the present invention, the formula for time integration of the first current is as follows: The formula for integrating the second current over time is: Where t0 is the start time of time integration and t is the end time of time integration. For the first current, For the first accumulated battery charge, For the second current, The difference is the second accumulated electricity amount. .

[0008] According to one embodiment of the present invention, the calculation of the set threshold is as follows: in, To set a threshold, k is a percentage between 0 and 100. For the first accumulated battery charge, The second accumulated energy is β, which is an adjustment coefficient. The adjustment coefficient β is the integral value of the energy storage system at the current acquisition resolution, and the formula for calculating the adjustment coefficient β is as follows: I*(t-t0), where I is the current acquisition resolution of the energy storage system, t0 is the start time for time integration, and t is the end time for time integration.

[0009] According to one embodiment of the present invention, k is 5% to 15%.

[0010] In particular, the present invention provides an energy storage battery management system, comprising: Energy storage battery unit; The battery control unit is connected to the energy storage battery unit on one side via a first DC bus, and to the power conversion unit on the other side via a second DC bus; The power conversion unit is connected to the battery control unit on one side and to a photovoltaic system or the power grid on the other side. A first current detection module is installed in the battery connection bus of the energy storage battery unit and is used to detect the current in the energy storage battery unit to obtain a first current. The second current detection module is located in the battery control unit and is used to detect the current of the first DC bus to obtain the second current. The control unit is configured to perform the energy storage system battery-side insulation monitoring method as described above to achieve insulation fault detection, and to control the on / off state of the corresponding current loop based on the result of the insulation fault detection.

[0011] According to one embodiment of the present invention, the energy storage battery unit includes at least one battery pack interconnected with each other, and the first current detection module is disposed in the battery pack of the energy storage battery unit; Alternatively, the energy storage battery unit includes a battery junction box and at least one battery pack connected to each other. Each battery pack is connected to the battery junction box, and the first current detection module is located in the battery junction box.

[0012] According to one embodiment of the present invention, a third switch is connected in series on the battery connection bus between two adjacent battery packs, and the on / off state of the third switch is controlled according to the result of the insulation fault detection.

[0013] According to one embodiment of the present invention, a first switch is connected in series on the first DC bus, and the on / off state of the first switch is controlled according to the result of the insulation fault detection. And / or, a second switch is connected in series on the second DC bus, and the on / off state of the second switch is controlled according to the result of the insulation fault detection.

[0014] According to one embodiment of the present invention, the controller may be set independently or integrated into the controller of the energy storage battery unit or the battery control unit.

[0015] Compared with existing technologies, the advantages and beneficial effects of the energy storage system battery-side insulation monitoring method and energy storage battery management system proposed in this patent application are as follows: The energy storage system battery-side insulation monitoring method of this application performs current detection at the near end of the battery pack in the energy storage battery unit and simultaneously performs current detection at the far end of the energy storage battery unit. Based on the integration of the two collected currents over a certain period of time, the cumulative charge is calculated. Based on the difference between the two cumulative charges, the insulation fault on the energy storage current side is determined. In other words, it can convert the instantaneous current value into the cumulative charge over a period of time, which can eliminate differential malfunctions caused by asynchronous current acquisition time, reduce the requirement for current acquisition synchronization, achieve reliable differential protection, realize real-time insulation monitoring on the current side of the energy storage system, and improve the reliability of insulation monitoring.

[0016] On the other hand, the hardware architecture of the energy storage battery management system of this application is simple, but it can reliably collect the first current and the second current in the insulation monitoring method, and based on the monitoring results of the method, it can quickly respond to the results to realize insulation protection, thereby improving the BMS protection response time under battery-side bus insulation abnormalities and short circuits. Attached Figure Description

[0017] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic diagram of the working process of the battery-side insulation monitoring method for an energy storage system according to Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the framework structure of the energy storage battery management system according to Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the framework structure of the energy storage battery management system according to Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the framework structure of the energy storage battery management system according to Embodiment 4 of the present invention. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0020] Example 1: This embodiment describes a method for monitoring battery-side insulation in an energy storage system. The energy storage system includes at least one battery pack, and the battery packs are interconnected to form an energy storage battery unit. The energy storage battery unit is connected to a subsequent circuit via a DC bus. For example... Figure 1 As shown, the current in the energy storage battery cell is detected to obtain a first current, and the current in the DC bus is detected to obtain a second current. Based on the difference between the first current and the second current, it is determined whether there is an insulation fault on the energy storage current side. If the difference between the first current and the second current is greater than a set threshold, then there is an insulation fault on the energy storage current side.

[0021] The determination of the difference between the first current and the second current includes: The first current and the second current are integrated over time to convert them into a first accumulated charge over a preset time period. With the second accumulated power Based on the first accumulated power With the second accumulated power Obtain the difference.

[0022] Specifically, the formula for integrating the first current over time is as follows: The formula for integrating the second current over time is: Where t0 is the start time of time integration and t is the end time of time integration. For the first current, For the first accumulated battery charge, For the second current, The difference is the second accumulated electricity amount. .

[0023] In existing technologies, the key to comparison and judgment based on multiple current acquisitions lies in the synchronization of the acquired current signals. However, in energy storage systems, traditional solutions require the addition of hardware synchronization signals or software synchronization clocks to achieve synchronous acquisition. Both of these solutions increase system complexity, leading to increased system costs and a relatively high error rate. To address this, this application integrates the current signal over time, converting the instantaneous current value into accumulated energy over a period of time. This reduces the requirement for current acquisition synchronization, eliminates differential malfunctions caused by asynchronous current acquisition times, and enables real-time insulation monitoring on the current side of the energy storage system. This not only improves the reliability of insulation monitoring but also reduces costs.

[0024] In one implementation, the set threshold is calculated as follows: in, To set the threshold, k is a percentage of 0-100 (generally, k is 5% to 15%). For the first accumulated battery charge, β is the second accumulated charge, and β is the adjustment coefficient.

[0025] The adjustment coefficient β is the integral value of the energy storage system at the current acquisition resolution, and the formula for calculating the adjustment coefficient β is as follows: I*(t-t0), where I is the current acquisition resolution of the energy storage system, t0 is the start time of time integration, and t is the end time of time integration. The current acquisition resolution of the energy storage system is generally between 1A and 3A, and is specifically determined based on the configuration of the energy storage system and the type of current acquisition unit selected.

[0026] Example 2: This embodiment describes an energy storage battery management system, such as Figure 2 As shown, it can generally include an energy storage battery unit, a battery control unit, a power change unit, a first current detection module, a second current detection module, and a control unit.

[0027] In this embodiment, the energy storage battery unit includes multiple battery packs connected in series. The first current detection module is disposed in the battery pack of the energy storage battery unit and is connected to the negative terminal of the battery pack. The output signal of the first current detection module can be directly fed back to the control unit, or the first current detection module can be connected to the battery pack level manager (BMU) in the battery pack, and the current acquisition signal can be fed back to the control unit through the battery pack level manager.

[0028] The battery control unit is connected to the energy storage battery unit on one side via a first DC bus, and to the power conversion unit on the other side via a second DC bus. The power conversion unit is connected to the battery control unit on one side and to a photovoltaic system or the power grid on the other side. A second current detection module is located in the battery control unit and is used to detect the current on the first DC bus to obtain a second current. The output signal of the second current detection module can be directly fed back to the control unit, or the first current detection module can be connected to the battery cluster management unit (BCU) in the battery control unit, and the BCU can feed back the current acquisition signal to the control unit.

[0029] The control unit is configured to execute the energy storage system battery-side insulation monitoring method as described in Example 1 to achieve insulation fault detection, and to control the on / off state of the corresponding current loop based on the result of the insulation fault detection.

[0030] In addition, a first switch is connected in series on the first DC bus, and the on / off state of the first switch is controlled based on the insulation fault detection result. A second switch is connected in series on the second DC bus, and the on / off state of the second switch is controlled based on the insulation fault detection result. By controlling the on / off state of the first or second switch, the current loop of the first or second DC bus is disconnected when necessary, thereby achieving insulation protection.

[0031] Example 3: This embodiment describes an energy storage battery management system, whose overall system architecture is the same as that of Embodiment 2, but the location of the first current detection module is different.

[0032] Specifically, the energy storage battery unit includes a battery junction box and multiple interconnected battery packs. Each battery pack is connected in series and then connected to the battery junction box. The first current detection module is located in the battery junction box, positioned between the positive and negative terminals. The first current detection module can directly feed back a current acquisition signal to the control unit, or it can feed back a current acquisition signal to the control unit through the battery pack-level manager.

[0033] Example 4: This embodiment describes an energy storage battery management system. Its overall system architecture is the same as that of Embodiment 3. The difference is that a third switch is provided in the energy storage battery unit. The third switch is connected in series on the battery connection bus between two adjacent battery packs. The third switch controls the opening and closing of the third switch according to the result of the insulation fault detection.

[0034] The control unit in Examples 2 to 4 can be set up independently and configured to execute the insulation monitoring method on the battery side of the energy storage system as described above to achieve insulation fault detection. The control unit obtains the current signals collected by the first current detection module and the second current detection module through a communication connection or a conductive connection, performs a preset workflow to achieve insulation fault detection, and controls one or more of the first switch, the second switch and the third switch to disconnect after obtaining the result of the insulation fault detection, thereby achieving insulation protection for the energy storage battery side.

[0035] In addition, the control unit is integrated into the controller of the energy storage battery unit or the battery control unit, such as integrating the execution program of the control unit into the battery pack level manager (BMU) or the battery cluster level manager (BCU).

[0036] As can be seen, the hardware architecture of the energy storage battery management system of this application is simple, but it can reliably collect the first current and the second current in the insulation monitoring method, and based on the monitoring results of the method, it can quickly respond to the results to realize insulation protection, thereby improving the BMS protection response time under battery-side bus insulation abnormalities and short circuits.

[0037] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for monitoring the insulation of a battery side of an energy storage system, the energy storage system comprising at least one battery pack, each battery pack being connected to each other to form an energy storage battery unit, the energy storage battery unit being connected to a subsequent circuit through a DC bus, characterized in that, Detecting the current in the energy storage battery unit to obtain a first current, detecting the current of the DC bus to obtain a second current, and determining whether there is an insulation fault on the energy storage current side based on the difference between the first current and the second current.

2. The energy storage system battery side insulation monitoring method of claim 1, wherein, The determination based on the difference between the first current and the second current comprises: The first current is time-integrated with the second current to convert into a first cumulative electric quantity within a preset time length and the second cumulative electric quantity , based on the first cumulative electric quantity and the second cumulative electric quantity to obtain a difference quantity.

3. The energy storage system battery side insulation monitoring method of claim 2, wherein, The formula for time integration of the first current is The formula for time integration of the second current is where t0 is the start time of the time integration, t is the end time of the time integration, is the first current, is the first accumulated electric quantity, is the second current, is the second accumulated electric quantity, and the difference quantity .

4. The energy storage system battery side insulation monitoring method according to claim 2 or 3, characterized by, The calculation of the threshold value is: wherein, k is a percentage of 0-100, is a first cumulative electric quantity, is a second cumulative electric quantity, and β is an adjustment coefficient, the adjustment coefficient β being an integral value under current collection resolution of the energy storage system, a calculation formula of the adjustment coefficient β being I*(t-t0), I being current collection resolution of the energy storage system, t0 being a starting time of time integration, and t being an ending time of time integration.

5. The energy storage system battery side insulation monitoring method of claim 4, wherein, k is 5% to 15%.

6. An energy storage battery management system, characterized by, Comprise: An energy storage battery unit; A battery control unit connected to the energy storage battery unit through a first DC bus on one side and connected to a power change unit through a second DC bus on the other side; A power change unit connected to the battery control unit on one side and connected to a photovoltaic or power grid on the other side; A first current detection module arranged in the battery connection bus of the energy storage battery unit for detecting the current in the energy storage battery unit to obtain a first current; A second current detection module arranged in the battery control unit for detecting the current of the first DC bus to obtain a second current; A control unit configured to perform the energy storage system battery side insulation monitoring method of any one of claims 1 to 6 to realize insulation fault detection, and control the on-off of the corresponding current loop according to the result of the insulation fault detection.

7. The energy storage battery management system of claim 6, wherein, The energy storage battery unit comprises at least one battery pack connected to each other, and the first current detection module is arranged in the battery pack of the energy storage battery unit. Or, the energy storage battery unit comprises a battery junction box and at least one battery pack connected to each other, and each battery pack is connected and then connected to the battery junction box, and the first current detection module is arranged in the battery junction box.

8. The energy storage battery management system of claim 7, wherein, A third switch is connected in series on the battery connection bus between two adjacent battery packs, and the on-off of the third switch is controlled according to the result of the insulation fault detection.

9. The energy storage battery management system of any one of claims 6-8, wherein, A first switch is connected in series on the first DC bus, and the on-off of the first switch is controlled according to the result of the insulation fault detection. And / or, a second switch is connected in series on the second DC bus, and the on-off of the second switch is controlled according to the result of the insulation fault detection.

10. The energy storage battery management system of claim 6, wherein, The controller is independently arranged or integrated in the controller of the energy storage battery unit or the battery control unit.

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