Energy storage system fault processing method based on BMS (Battery Management System)

Abstract

The invention relates to an energy storage system fault processing method based on a BMS system, an energy storage system comprises a plurality of energy storage battery modules, each energy storage battery module comprises a battery pack and a power conversion unit which are connected in sequence, the energy storage system is managed through the BMS system, and the method comprises the steps of obtaining a first state parameter of each battery pack, comprising battery pack voltage, battery pack charging and discharging current and battery pack temperature; acquiring a second state parameter of each power conversion unit, wherein the second state parameter comprises an input voltage, an output voltage, an input current and an output current of the power conversion unit; calculating a fault probability index of the energy storage system according to the first state parameter, the second state parameter and the internal protection parameter; and when the fault probability index exceeds a preset safety threshold value, performing module switching operation on the energy storage battery module where the battery pack and the power unit are located, so as to solve the problems that potential faults cannot be found in time when the energy storage system has faults, and fault processing measures may influence the operation of the whole system.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of power system energy storage, and in particular to a method for handling energy storage system faults based on a BMS system. Background Art

[0002] The battery management system (BMS) is mainly used to manage and monitor the working status of the battery, for example, it can monitor and diagnose the faults of the battery energy storage system. The existing energy storage system fault handling method usually detects the fault by monitoring a single parameter, and adopts a handling method such as cutting off the entire energy storage system after the fault occurs. However, this method cannot detect potential faults in time, and the above fault handling measures may affect the operation of the entire system.

[0003] Therefore, it is urgent to propose a fault handling method for an energy storage system based on a BMS system to solve the technical problems that the energy storage system fault handling method cannot detect potential faults in time when a fault occurs, and the above-mentioned fault handling measures may affect the operation of the entire system. Summary of the invention

[0004] Based on the above situation of the prior art, the purpose of an embodiment of the present invention is to provide a fault handling method for an energy storage system based on a BMS system, so as to solve the technical problem that the fault handling method for the energy storage system cannot detect potential faults in time when a fault occurs, and the above fault handling measures may affect the operation of the entire system.

[0005] To achieve the above object, according to one aspect of the present invention, a method for handling energy storage system faults based on a BMS system is provided, wherein the energy storage system includes a plurality of energy storage battery modules, each of which includes a battery pack and a power conversion unit connected in sequence, and the energy storage system is managed by the BMS system, comprising the following steps:

[0006] Acquire a first state parameter of each battery pack, wherein the first state parameter includes a battery pack voltage, a battery pack charge and discharge current, and a battery pack temperature;

[0007] Acquire a second state parameter of each power conversion unit, wherein the second state parameter includes an input voltage, an output voltage, an input current, and an output current of the power conversion unit;

[0008] Calculating a failure probability index of the energy storage system according to the first state parameter, the second state parameter and an internal protection parameter;

[0009] When the failure probability index exceeds a preset safety threshold, a module cutting operation is performed on the energy storage battery module where the battery pack and the power unit are located.

[0010] Furthermore, the calculating of the failure probability index of the energy storage system according to the first state parameter, the second state parameter and the internal protection parameter specifically includes the following steps:

[0011] The failure probability index P of the energy storage system is calculated using the following formula: f :

[0012] P f =α V ·R V +α I ·R I +α T ·R T +α V-in-out ·R V-in-out +α I-in-out ·

[0013] R I-in-out +α PS ·R PS ;

[0014] Among them, R V Indicates the battery pack voltage abnormality rate, R I Indicates the abnormal current rate of the battery pack, R T Indicates the battery pack temperature abnormality rate, R V-in-out Indicates the voltage abnormality rate of the power conversion unit, R I-in-out Indicates the abnormal current rate of the power conversion unit, R PS represents the internal protection parameter, α V , α I , α T , α V-in-out , α I-in-out and α PS are the weight coefficients of each item respectively.

[0015] Further, the internal protection parameters include an overcurrent protection signal, an overvoltage protection signal and a short circuit protection signal. When any one of the overcurrent protection signal, the overvoltage protection signal and the short circuit protection signal is effective, R PS =1, otherwise R PS =0.

[0016] Furthermore, the battery pack voltage abnormality rate, the battery pack current abnormality rate, the battery pack temperature abnormality rate, the power conversion unit voltage abnormality rate and the power conversion unit current abnormality rate are calculated according to the following formula:

[0017] R V =N V / N total ;

[0018] R I =T I / Δt;

[0019] R T =N T / N T-total ;

[0020] R V-in-out =T V-in-out / Δt;

[0021] R I-in-out =T I-in-out / Δt;

[0022] Among them, N V Indicates the number of abnormal voltage battery cells in the battery pack, N total Indicates the total number of battery cells in the battery pack, T I represents the duration of abnormal battery current, Δt represents the time interval for parameter monitoring of the energy storage battery module, N T The number of temperature monitoring points indicating abnormal temperature in the battery pack, N T-total Indicates the total number of temperature monitoring points, T V-in-out Indicates the abnormal input and output voltage duration of the power conversion unit, T I-in-out Indicates the abnormal input and output current duration of the power conversion unit.

[0023] Furthermore, when the failure probability index exceeds a preset safety threshold, the energy storage battery module where the battery pack and the power unit are located is cut off, which specifically includes the following steps:

[0024] Control the controllable switch corresponding to the energy storage battery module to disconnect so as to cut off the connection between the energy storage battery module and the busbar, wherein the several energy storage battery modules are respectively connected to the busbar through the controllable switches, and the busbar is connected to the power grid through the bidirectional converter and the transformer.

[0025] Furthermore, the module cutting operation on the energy storage battery module where the battery pack and the power unit are located further includes the following steps:

[0026] After the module cutting operation, the output power of the remaining energy storage battery modules is adjusted.

[0027] Furthermore, the power of the remaining energy storage battery modules is adjusted, specifically comprising the following steps:

[0028] When the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, power regulation is performed using the BMS system;

[0029] When the grid state parameter exceeds the grid state threshold, the bidirectional converter is used to adjust the power.

[0030] Furthermore, when the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, power regulation is performed using the BMS system, which specifically includes the following steps:

[0031] The power of each battery pack is allocated according to the SOC and SOH of the battery pack in each energy storage battery module, wherein the internal difference coefficient is the sum of the SOC difference coefficient and the SOH difference coefficient of the battery pack in the remaining energy storage battery modules, and the allocated power P new-i Calculate using the following formula:

[0032] P new-i =P rated-i ·k i ;

[0033] Among them, P rated-i Indicates the rated power of the battery pack, k i Indicates the power adjustment factor.

[0034] Furthermore, the SOC difference coefficient D SOC The calculation formula is as follows:

[0035]

[0036] Among them, SOC max Indicates the maximum SOC value, SOC min Indicates the minimum SOC value, SOC avg Indicates the average SOC value;

[0037] The SOH difference coefficient D SOH The calculation formula is as follows:

[0038]

[0039] Among them, SOH max Indicates the maximum value of SOH, SOH min Indicates the minimum SOH value, SOH avg Indicates the average SOH value.

[0040] Furthermore, when the grid state parameter exceeds the grid state threshold, power regulation is performed using a bidirectional converter, specifically comprising the following steps:

[0041] When the grid frequency deviation exceeds the frequency deviation threshold and / or the voltage fluctuation ratio exceeds the fluctuation ratio threshold, calculating the power regulation amount of the bidirectional converter according to the grid frequency deviation and / or the voltage fluctuation ratio;

[0042] Adjusting the output power of the bidirectional converter according to the power adjustment amount of the bidirectional converter;

[0043] According to the power adjustment amount, the power change value of each energy storage battery module is calculated, and the power of the remaining energy storage battery modules is adjusted based on the power change value.

[0044] In summary, the embodiment of the present invention provides a method for handling energy storage system faults based on a BMS system, by obtaining the first state parameter of each battery pack, the first state parameter including the battery pack voltage, the battery pack charge and discharge current and the battery pack temperature, and obtaining the second state parameter of each power conversion unit, the second state parameter including the input voltage, output voltage, input current and output current of the power conversion unit, so as to fully and meticulously understand the real-time operating status of each key component of the energy storage system, and provide a rich and detailed data basis for the subsequent accurate judgment of the health of the system; according to the first state parameter, the second state parameter and the internal protection parameter, the failure probability index of the energy storage system is calculated to achieve The possibility of failure that was originally difficult to judge intuitively is quantified and presented; when the failure probability index exceeds the preset safety threshold, the energy storage battery module where the battery pack and the power unit are located is cut, which can quickly isolate the modules that may fail or are already in a critical state of failure from the entire energy storage system. Based on the orderly development of the BMS system, with the help of its automated data collection, analysis and corresponding control functions, compared with the traditional operation and maintenance method that relies on manual inspection and experience judgment, it can locate potential faulty modules more efficiently and accurately, and take timely treatment measures such as cutting modules, which helps to reduce operation and maintenance costs, extend the overall service life of the energy storage system, and ensure the long-term stable and reliable operation of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 is a schematic diagram of the overall structure of the energy storage system provided by an embodiment of the present invention;

[0046] Figure 2 is a schematic structural diagram of an energy storage system according to an embodiment of the invention;

[0047] Figure 3 It is a flow chart of a method for handling energy storage system faults based on a BMS system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0049] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in one or more embodiments of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0050] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. An embodiment of the present invention provides a method for handling energy storage system faults based on a BMS system, where the BMS system is used to manage the energy storage system. The method for handling energy storage system faults provided by an embodiment of the present invention can be applied to monitoring and handling faults in energy storage systems. Figure 1 The overall structure diagram of the energy storage system provided by the embodiment of the present invention is shown in FIG. Figure 1 As shown, the BMS system is connected to the energy storage system to monitor operating parameters, faults and process the energy storage system. The energy storage system is connected to the power grid through a bidirectional converter and a transformer. Figure 2 The schematic diagram of the structure of the energy storage system according to the embodiment of the present invention is shown in FIG. Figure 2 As shown, the energy storage system includes several energy storage battery modules, each of which includes a battery pack and a power conversion unit connected in sequence. Several energy storage battery modules are connected to the busbar through controllable switches, and the busbar is connected to the power grid through a bidirectional converter and a transformer. Among them, each battery pack is composed of a plurality of battery cells connected in series. When the energy storage system is in the discharge mode, it transmits power to the power grid, and the bidirectional converter converts the direct current output by each energy storage battery module into alternating current that meets the requirements of the power grid. When the energy storage system is in the charging mode, the bidirectional converter converts the alternating current into direct current to charge the battery pack of each energy storage battery module.

[0051] like Figure 3 FIG. 1 is a flow chart of a method for handling energy storage system faults based on a BMS system provided by an embodiment of the present invention. The method comprises the following steps:

[0052] S202: Obtain a first state parameter of each battery pack, where the first state parameter includes a battery pack voltage, a battery pack charge and discharge current, and a battery pack temperature.

[0053] S204. Obtain second state parameters of each power conversion unit, where the second state parameters include input voltage, output voltage, input current, and output current of the power conversion unit.

[0054] The BMS system is provided with various sensors for monitoring the status parameters of the energy storage battery module, and the first status parameters of the battery pack and the second status parameters of the power conversion unit can be obtained in real time through the sensors.

[0055] S206. Calculate the failure probability index of the energy storage system according to the first state parameter, the second state parameter and the internal protection parameter. The first state parameter and the second state parameter are operating parameters of the energy storage battery module, which can indicate the operating state of the energy storage battery module. The internal protection parameter refers to fault protection signals such as overcurrent protection signal, overvoltage protection signal and short circuit protection signal, for example, issued by other internal protection devices of the system.

[0056] In the embodiment of the present invention, the following formula is used to calculate the failure probability index P of the energy storage system: f :

[0057] P f =α V ·R V +α I ·R I +α T ·R T +α V-in-out ·R V-in-out +α I-in-out ·

[0058] R I-in-out +α PS ·R PS ;

[0059] Among them, R V Indicates the battery pack voltage abnormality rate, R I Indicates the abnormal current rate of the battery pack, R T Indicates the battery pack temperature abnormality rate, R V-in-out Indicates the voltage abnormality rate of the power conversion unit, R I-in-out Indicates the abnormal current rate of the power conversion unit, R PS Represents internal protection parameters; α V , α I , α T , α V-in-out , α I-in-out and α PSare the weight coefficients of each item. The value of each weight coefficient can be set according to the importance of each item in the formula to fault judgment, and the sum of the values ​​of each weight coefficient is 1. Among them, when any one of the overcurrent protection signal, overvoltage protection signal and short-circuit protection signal is valid, the internal protection parameter R PS =1, otherwise R PS =0. In the above formula, each abnormality rate can be calculated according to the following formulas:

[0060] R V =N V / N total ;

[0061] The BMS system monitors the parameters of each energy storage battery module at a fixed time interval (for example, Δt), including voltage, current, and temperature. The battery pack in the energy storage battery module monitors the battery cell voltage. When the voltage of a battery cell exceeds the preset normal voltage threshold, the battery cell is marked as an abnormal voltage battery cell. V Indicates the number of abnormal voltage battery cells in the battery pack, N total It indicates the total number of battery cells in the battery pack, and the ratio of the two reflects the abnormal voltage rate of the battery pack.

[0062] R I =T I / Δt;

[0063] The BMS system monitors the charging current and discharging current of the battery pack in the energy storage battery module at the same time. If the charging current or discharging current exceeds the preset normal current range, the current abnormality is marked. I It indicates the duration of abnormal battery current, Δt indicates the time interval for parameter monitoring of the energy storage battery module, and the ratio of the two reflects the abnormal battery current rate.

[0064] R T =N T / N T-total ;

[0065] Monitor the temperature of the battery pack in the energy storage battery module and record the temperature value of each temperature monitoring point. When the temperature value of a temperature monitoring point exceeds the preset normal temperature range, the temperature monitoring point is marked as a temperature abnormality monitoring point. T The number of temperature monitoring points indicating abnormal temperature in the battery pack, N T-totalIndicates the total number of temperature monitoring points, and the ratio of the two reflects the battery pack temperature abnormality rate. The temperature monitoring points may be set at different positions of the battery cells in the battery pack. A suitable temperature monitoring point may be set for each battery cell, or a temperature monitoring point may be set at a specific position of the battery pack, such as some positions that are sensitive to temperature. The present invention does not limit the specific setting position and number of the temperature monitoring points.

[0066] R V-in-out =T V-in-out / Δt;

[0067] The BMS system can also monitor the input voltage and output voltage of the power conversion unit in the energy storage battery module. If the input voltage or output voltage exceeds the preset input voltage threshold or output voltage threshold, it will be marked as input and output voltage abnormality. V-in-out It indicates the duration of abnormal input and output voltage of the power conversion unit, Δt indicates the time interval for parameter monitoring of the energy storage battery module, and the ratio of the two reflects the voltage abnormality rate of the power conversion unit.

[0068] R I-in-out =T I-in-out / Δt;

[0069] Monitor the input current and output current of the power conversion unit. If the input current or output current exceeds the preset input current threshold or output current threshold, it is marked as input and output current abnormality. I-in-out It indicates the duration of abnormal input and output current of the power conversion unit, Δt indicates the time interval for parameter monitoring of the energy storage battery module, and the ratio of the two reflects the abnormal current rate of the power conversion unit.

[0070] S208, when the failure probability index exceeds the preset safety threshold, the energy storage battery module where the battery group and the power unit are located is cut off. When the failure probability index of a certain energy storage battery module exceeds the preset safety threshold, the controllable switch corresponding to the energy storage battery module can be controlled to be disconnected to cut off the connection between the energy storage battery module and the busbar, thereby cutting off the faulty energy storage battery module from the system to prevent the failure of a single module from affecting the operation of the entire system.

[0071] The method provided in this embodiment obtains the first state parameter of each battery pack, wherein the first state parameter includes the battery pack voltage, the battery pack charge and discharge current, and the battery pack temperature, and obtains the second state parameter of each power conversion unit, wherein the second state parameter includes the input voltage, the output voltage, the input current, and the output current of the power conversion unit. This method can comprehensively and meticulously understand the real-time operating conditions of the key components of the energy storage system, and provide a rich and detailed data basis for subsequent accurate judgment of the health of the system; based on the first state parameter, the second state parameter, and the internal protection parameter, the fault probability index of the energy storage system is calculated, and the fault that was originally difficult to intuitively judge is realized. The possibility is quantified and presented; when the failure probability index exceeds the preset safety threshold, the energy storage battery module where the battery pack and the power unit are located is cut, which can quickly isolate the modules that may fail or are already in a critical state of failure from the entire energy storage system. Based on the orderly development of the BMS system, with the help of its automated data collection, analysis and corresponding control functions, compared with the traditional operation and maintenance method that relies on manual inspection and experience judgment, it can locate potential faulty modules more efficiently and accurately, and take treatment measures such as cutting modules in time, which is helpful to reduce operation and maintenance costs, extend the overall service life of the energy storage system, and ensure the long-term stable and reliable operation of the energy storage system.

[0072] According to some optional embodiments, after performing the module cutting operation in step S208, the method further includes the steps of:

[0073] S210. Adjust the output power of the remaining energy storage battery modules. When a certain energy storage battery module is removed, the electrical characteristics of the entire energy storage system change. If power adjustment is not performed, the output power of the remaining energy storage battery modules may exceed the safety range of the system design, resulting in system overload or unstable parameters such as voltage and current. In addition, inappropriate power output may accelerate the aging and damage of the remaining energy storage battery modules. If after a certain energy storage battery module is removed, the remaining energy storage battery modules continue to output too high a power, the chemical reaction inside the battery will intensify, the temperature will rise, etc., thereby shortening the service life of the battery. In an embodiment of the present invention, the output power of the remaining energy storage battery modules is adjusted, and different methods of power adjustment can be selected based on the internal state differences of the remaining energy storage battery modules and the state parameters of the power grid.

[0074] According to certain optional embodiments, when the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, the BMS system is used to perform power regulation, and when the grid state parameters exceed the grid state threshold, the bidirectional converter is used to perform power regulation.

[0075] When the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, the BMS system is used to adjust the power, and the following steps can be adopted:

[0076] S21011. Obtain the state of charge (SOC) and state of health (SOH) of the battery packs in the remaining energy storage battery modules. For example, obtain the SOC and SOH of each battery pack in the remaining energy storage battery modules by collecting and calculating the SOC and SOH of each battery pack in the remaining energy storage battery modules through the BMS system.

[0077] S21012, obtain the maximum SOC value SOC max 、SOC minimum value SOC min and SOC average SOC avg , calculate the SOC difference coefficient D SOC :

[0078]

[0079] S21013, get the maximum SOH value SOH max 、SOH minimum value SOH min and SOH average SOH avg , calculate the SOH difference coefficient D SOH :

[0080]

[0081] S21014, when the internal difference coefficient D total When the difference coefficient threshold is exceeded, the BMS is used to adjust the power. The internal difference coefficient D total is the SOC difference coefficient D SOC Difference coefficient D with SOH SOH The power of each battery pack can be allocated according to the SOC and SOH of each energy storage battery module battery pack, and the allocated power P new-i Calculate using the following formula:

[0082] P new-i =P rated-i ·k i ;

[0083] Among them, P rated-i represents the rated power of battery pack i, k i Indicates the power adjustment factor, which is related to the SOC and SOH of the battery pack, as well as the charging and discharging status of the battery pack. When the battery pack in the energy storage battery module is in the charging state,

[0084] k i =1+ω1(SOC i-SOC min )-ω2(SOH max -SOH i );

[0085] When the battery pack in the energy storage battery module is in a discharging state,

[0086] k i =1-ω1(SOC max -SOC i )-ω2(SOH max -SOH i );

[0087] Among them, ω1 and ω2 represent weight coefficients, which are used to measure the relative importance of SOC and SOH to power adjustment, satisfying ω1+ω2=1; SOC i Indicates the SOC and SOH of battery pack i i Represents the SOH of battery pack i. When the battery pack in the energy storage battery module is in a discharging state, the energy storage battery modules with higher SOC and SOH can bear relatively more discharging power to fully utilize the power of the battery pack; when the battery pack in the energy storage battery module is in a charging state, the energy storage battery modules with lower SOC can obtain relatively more charging power, the energy storage battery modules with higher SOH can be charged with relatively higher power, and the energy storage battery modules with lower SOH can be charged with relatively lower power.

[0088] When the grid state parameter exceeds the grid state threshold, the bidirectional converter is used for power regulation, and the following steps can be adopted:

[0089] S21021. Obtain real-time grid frequency and real-time grid voltage.

[0090] S21022. Calculate the grid frequency deviation Δf according to the real-time grid frequency:

[0091] Δf=f grid -f n ;

[0092] Among them, f grid Indicates the real-time grid frequency, f n Indicates the rated frequency of the power grid.

[0093] S21023. Calculate the voltage fluctuation ratio based on the real-time grid voltage:

[0094]

[0095] Among them, V grid Indicates the real-time grid voltage, V n Indicates the rated voltage of the power grid.

[0096] S21024. When the grid frequency deviation exceeds the frequency deviation threshold, and / or the voltage fluctuation ratio exceeds the fluctuation ratio threshold, the power regulation amount of the bidirectional converter is calculated according to the grid frequency deviation and / or the voltage fluctuation ratio.

[0097] The grid frequency deviation and power regulation usually follow the droop characteristic. The droop characteristic means that when the grid frequency decreases, the energy storage system (through the bidirectional converter) should inject active power into the grid; when the grid frequency increases, the energy storage system (through the bidirectional converter) should absorb active power from the grid. When the grid frequency deviation exceeds the frequency deviation threshold, the power regulation amount ΔP of the bidirectional converter can be expressed as:

[0098] ΔP=-k f Δf;

[0099] k f Indicates the power droop coefficient, the power droop coefficient k f The determination of the energy storage system needs to consider the rated power P rated , the frequency deviation range allowed by the power grid Δf max , and the expected contribution of the energy storage system to grid frequency regulation σ, where the value of σ is less than 1.

[0100] k f =σ*P rated / Δf max ;

[0101] Grid voltage fluctuations mainly affect the balance of reactive power, and there is also a droop characteristic between grid voltage fluctuations and reactive power regulation. When the grid voltage drops, the energy storage system (through the bidirectional converter) should inject reactive power into the grid to support the voltage; when the grid voltage rises, the energy storage system (through the bidirectional converter) should absorb reactive power from the grid. When the voltage fluctuation ratio exceeds the fluctuation ratio threshold, the reactive regulation amount ΔQ of the bidirectional converter can be expressed as:

[0102] ΔQ=-k v ΔV;

[0103] k v Indicates the voltage droop coefficient, voltage droop coefficient k v The determination of the reactive power capacity Q of the energy storage system needs to be considered rated , the voltage fluctuation range allowed by the power grid ΔV max , and the expected contribution of the energy storage system to grid voltage regulation τ, where the value of τ is less than 1.

[0104] k v =τ*Q rated / ΔV max ;

[0105] S21025, adjusting the output power of the bidirectional converter according to the power adjustment amount of the bidirectional converter. Based on the power adjustment amount calculated in the above steps, a suitable power control algorithm can be used to adjust the output power of the bidirectional converter, and the present invention does not make any specific limitation on this.

[0106] S21026. Calculate the power change value of each energy storage battery module according to the power adjustment amount, and adjust the power of the remaining energy storage battery modules based on the power change value. Calculate the power allocation weight of the remaining energy storage battery modules:

[0107]

[0108] Among them, γ i represents the power allocation weight of energy storage battery module i, P rated-i Represents the rated power of the battery pack in the energy storage battery module i, SOC i represents the SOC of battery pack i, and n represents the number of remaining energy storage battery modules.

[0109] According to the amplitude |S| and phase θ of the power regulation amount, the active power change value ΔP of each energy storage battery module is calculated i And reactive power change value ΔQ i :

[0110] ΔP i =γ i |S|cosθ;

[0111] ΔQ i =γ i |S|sinθ;

[0112]

[0113] Based on the active power change value ΔP of each energy storage battery module i And reactive power change value ΔQ i , the power of the remaining energy storage battery modules can be adjusted through the BMS system.

[0114] In summary, the embodiment of the present invention relates to a method for handling energy storage system faults based on a BMS system, comprising the steps of: obtaining a first state parameter of each battery pack; obtaining a second state parameter of each power conversion unit; calculating a fault probability index of the energy storage system according to the first state parameter, the second state parameter and the internal protection parameter; and performing a module cutting operation on the energy storage battery module where the battery pack and the power unit are located when the fault probability index exceeds a preset safety threshold. The technical solution provided by the embodiment of the present invention uses a fault probability index to indicate the fault of the energy storage battery module, which not only considers the operating parameters of the battery pack in the energy storage battery module, but also considers the voltage and current parameters of the power conversion unit, thereby realizing comprehensive monitoring of the energy storage battery module. The monitoring of the above parameters can detect the potential fault risks that may exist in advance before the energy storage battery module fails or before the fault affects the overall operation of the system, thereby reducing the adverse effects of the fault on the system operation. By calculating the fault probability index of the energy storage system for each energy storage battery module, the fault can be accurately located to the energy storage battery module, which helps to find the cause of the fault as soon as possible, thereby improving the efficiency of fault handling.

[0115] It should be understood that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention (including claims) is limited to these examples; under the idea of ​​the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of one or more embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. The above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the scope of protection of the present invention. In addition, the claims attached to the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the attached claims, or the equivalent forms of such scope and boundaries.

Claims

1. A method for handling energy storage system faults based on a BMS system, characterized in that: The energy storage system includes a plurality of energy storage battery modules, each of which includes a battery pack and a power conversion unit connected in sequence. The energy storage system is managed by a BMS system, including the following steps: Acquire a first state parameter of each battery pack, wherein the first state parameter includes a battery pack voltage, a battery pack charge and discharge current, and a battery pack temperature; Acquire a second state parameter of each power conversion unit, wherein the second state parameter includes an input voltage, an output voltage, an input current, and an output current of the power conversion unit; Calculating a failure probability index of the energy storage system according to the first state parameter, the second state parameter and an internal protection parameter; When the failure probability index exceeds a preset safety threshold, a module cutting operation is performed on the energy storage battery module where the battery pack and the power unit are located.

2. The method according to claim 1, characterized in that The calculating the failure probability index of the energy storage system according to the first state parameter, the second state parameter and the internal protection parameter specifically comprises the following steps: The failure probability index P of the energy storage system is calculated using the following formula: f : P f =a V ·R V +a I ·R I +a T ·R T +a V-in-out ·R V-in-out +a I-in-out · R I-in-out +a PS ·R PS ; Among them, R V Indicates the battery pack voltage abnormality rate, R I Indicates the abnormal current rate of the battery pack, R T Indicates the battery pack temperature abnormality rate, R V-in-out Indicates the voltage abnormality rate of the power conversion unit, R I-in-out Indicates the abnormal current rate of the power conversion unit, R PS represents the internal protection parameter, α V , α I , α T , α V-in-out , α I-in-out and α PS are the weight coefficients of each item respectively.

3. The method according to claim 2, characterized in that The internal protection parameters include an overcurrent protection signal, an overvoltage protection signal and a short circuit protection signal. When any one of the overcurrent protection signal, the overvoltage protection signal and the short circuit protection signal is valid, R PS =1, otherwise R PS =0.

4. The method according to claim 2, characterized in that: The battery pack voltage abnormality rate, battery pack current abnormality rate, battery pack temperature abnormality rate, power conversion unit voltage abnormality rate and power conversion unit current abnormality rate are calculated according to the following formula: R V =N V / N total ; R I =T I / Δt; R T =N T / N T-total ; R V-in-out =T V-in-out / Δt; R I-in-out =T I-in-out / Δt; Among them, N V Indicates the number of abnormal voltage battery cells in the battery pack, N total Indicates the total number of battery cells in the battery pack, T I represents the duration of abnormal battery current, Δt represents the time interval for parameter monitoring of the energy storage battery module, N T The number of temperature monitoring points indicating abnormal temperature in the battery pack, N T-total Indicates the total number of temperature monitoring points, T V-in-out Indicates the abnormal input and output voltage duration of the power conversion unit, T I-in-out Indicates the abnormal input and output current duration of the power conversion unit.

5. The method according to claim 1, characterized in that When the failure probability index exceeds a preset safety threshold, performing a module cutting operation on the energy storage battery module where the battery pack and the power unit are located specifically includes the following steps: Control the controllable switch corresponding to the energy storage battery module to disconnect so as to cut off the connection between the energy storage battery module and the busbar, wherein the several energy storage battery modules are respectively connected to the busbar through the controllable switches, and the busbar is connected to the power grid through the bidirectional converter and the transformer.

6. The method according to claim 1, characterized in that The module cutting operation of the energy storage battery module where the battery pack and the power unit are located also includes the following steps: After the module cutting operation, the output power of the remaining energy storage battery modules is adjusted.

7. The method according to claim 6, characterized in that The power of the remaining energy storage battery modules is adjusted, specifically comprising the following steps: When the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, power regulation is performed using the BMS system; When the grid state parameter exceeds the grid state threshold, the bidirectional converter is used to adjust the power.

8. The method according to claim 7, characterized in that When the internal difference coefficients of the remaining energy storage battery modules exceed the difference coefficient threshold, power regulation is performed using the BMS system, specifically including the following steps: The power of each battery pack is allocated according to the SOC and SOH of the battery pack in each energy storage battery module, wherein the internal difference coefficient is the sum of the SOC difference coefficient and the SOH difference coefficient of the battery pack in the remaining energy storage battery modules, and the allocated power P new-i Calculate using the following formula: P new-i =P rated-i ·k i ; Among them, P rated-i Indicates the rated power of the battery pack, k i Indicates the power adjustment factor.

9. The method according to claim 8, characterized in that The SOC difference coefficient D SOC The calculation formula is as follows: Among them, SOC max Indicates the maximum SOC value, SOC min Indicates the minimum SOC value, SOC avg Indicates the average SOC value; The SOH difference coefficient D SOH The calculation formula is as follows: Among them, SOH max Indicates the maximum value of SOH, SOH min Indicates the minimum SOH value, SOH avg Indicates the average SOH value.

10. The method according to claim 7, characterized in that When the grid state parameter exceeds the grid state threshold, power regulation is performed using the bidirectional converter, specifically comprising the following steps: When the grid frequency deviation exceeds the frequency deviation threshold and / or the voltage fluctuation ratio exceeds the fluctuation ratio threshold, calculating the power regulation amount of the bidirectional converter according to the grid frequency deviation and / or the voltage fluctuation ratio; Adjusting the output power of the bidirectional converter according to the power adjustment amount of the bidirectional converter; According to the power adjustment amount, the power change value of each energy storage battery module is calculated, and the power of the remaining energy storage battery modules is adjusted based on the power change value.

Images