On-load discharge capacity checking method and system for storage battery pack of direct current system of transformer substation

Abstract

The invention discloses a transformer station DC system storage battery pack on-load discharge capacity checking method and system, and relates to the technical field of storage battery discharge maintenance, and the method comprises the steps: carrying out the equalizing charging of a storage battery pack through an equalizing charging voltage, and collecting the internal resistance of a single storage battery before capacity checking; after capacity checking is started, an intelligent electronic load value is adjusted, so that the output current of the storage battery pack keeps a constant set value; when a test ending condition is met, obtaining nuclear capacity discharge capacity according to the discharge current and the discharge time of the storage battery pack; the storage battery pack is charged after charging is finished, the capacity checking charging capacity is obtained according to the charging current and the charging time, and the internal resistance of the single storage batteries after capacity checking is collected after charging is finished; and generating an on-load discharge capacity checking test table according to the internal resistance of the single storage battery before capacity checking, the capacity checking discharge capacity, the capacity checking charge capacity and the internal resistance of the single storage battery after capacity checking so as to complete capacity checking of the storage battery pack. Remote online capacity checking is realized, and the problem of low reliability of the whole group of storage batteries caused by virtual connection of storage battery connecting strips or performance reduction of a single storage battery is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery discharge maintenance, in particular to a method and system for on-load discharge capacity check of a battery pack of a substation DC system. BACKGROUND

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

[0003] When the performance of any one battery in the battery pack of the substation DC system does not meet the requirements, the entire battery pack will be directly disabled, which brings great security risks to the operation of the substation. However, the means for mastering the capacity performance of the series-connected battery pack is single. The battery float voltage and internal resistance data can assist in the judgment but cannot truly reflect the capacity performance. Although the capacity performance of the battery can be verified through the checking discharge test, the interval period of the checking discharge test is as long as one year.

[0004] In addition, the traditional battery pack of the substation DC power supply system cannot be checked online, and can only be checked offline by disconnecting the battery pack from the DC system. However, if the AC power supply is lost at this time, the protection and control devices of the entire station will be lost. Secondly, the new technologies such as parallel power supply system and DC guardian power supply system require a large range of modification and high cost for the traditional DC power supply system. Furthermore, the short-time on-load discharge can only preliminarily judge whether the capacity of the battery pack is qualified, and cannot quantitatively analyze the capacity of the battery. SUMMARY

[0005] In order to solve the above problems, the present application provides a method and system for on-load discharge capacity check of a battery pack of a substation DC system, which realizes remote online capacity check without disconnecting the battery pack from the bus, solves the problem of reduced reliability of the entire battery caused by virtual connection of the battery connection strip or performance degradation of the single battery, and has small modification workload and low cost for the DC system.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme: In a first aspect, the present application provides a method for on-load discharge capacity check of a battery pack of a substation DC system, which is applied to a battery pack composed of a plurality of battery monomers in series connection, and an intelligent electronic load is connected in parallel with the original load; comprising: After the battery pack is balanced charged at the equalizing voltage, the internal resistance of the battery monomer before capacity check is collected; After the capacity check is started, the battery pack supplies power to the original load, the output current of the battery pack and the bus load current are collected, the intelligent electronic load value is adjusted according to the bus load current, so that the output current of the battery pack remains constant at the set value; When the set battery pack load discharge test end condition is reached, the capacity discharge capacity is obtained according to the battery pack discharge current and the discharge time; and after the battery pack load discharge test is completed, the battery pack is charged, the capacity charging capacity is obtained according to the charging current and the charging time, and the capacity after the battery cell resistance is collected after the charging is completed; According to the capacity before the battery cell resistance, the capacity discharge capacity, the capacity charging capacity and the capacity after the battery cell resistance, the load discharge capacity test table is generated, and the capacity of the battery pack is completed.

[0007] As an optional implementation, the process of balancing charging the battery pack at the equal charging voltage includes: controlling the output voltage of the boost charging module to the equal charging voltage according to the set value, so as to balance charge the battery pack at the equal charging voltage.

[0008] As an optional implementation, after collecting the capacity before the battery cell resistance, the output voltage of the boost charging module is controlled to the equal charging voltage again according to the set value, so as to balance charge the battery pack at the equal charging voltage.

[0009] As an optional implementation, the output voltage of the boost charging module is controlled according to the set value, so that the output voltage of the charging module is lower than the terminal voltage of the battery pack within a set time period, at which time the battery pack supplies power to the original load, and the capacity is started.

[0010] As an optional implementation, if the terminal voltage of the battery pack remains higher than the set value within a set time period, or reaches a set discharge depth, the battery pack load discharge test is ended after the set time is reached; wherein the set discharge depth is set to 20%, 50%, 80% or 100%.

[0011] As an optional implementation, the process of adjusting the intelligent electronic load value according to the bus load current includes: setting the difference between the output current set value and the bus load current as the current to be consumed by the intelligent electronic load, setting the current to be consumed by the intelligent electronic load to the intelligent electronic load, so that the bus load current is the output current of the battery pack, and the output current set value is kept constant.

[0012] As an optional implementation, the battery pack load discharge test has a balancing charging lock function. During the battery pack load discharge test, if the balancing charging condition is met, the balancing charging is started after the test is completed, and the load discharge test is not allowed to be started during the balancing charging process.

[0013] As an optional implementation, the battery pack is also connected in parallel with a standby power supply, so as to avoid the situation that the connection strip is virtually connected or a single battery cell fails in the battery pack during the capacity test, resulting in that the battery pack cannot be discharged.

[0014] As an alternative embodiment, the battery pack is also connected with an insulation monitoring module for monitoring whether there is a ground fault in the battery pack, and if so, the nuclear capacity function is not started or stopped, and the position of the grounded battery is determined.

[0015] In a second aspect, the application provides a substation DC system battery pack load discharge nuclear capacity system, comprising: an intelligent power monitoring device, and a charging module, a battery pack, an intelligent electronic load and an actual load connected in parallel, the battery pack is composed of a plurality of battery monomers in series, and the battery pack is also connected with a DC analog quantity acquisition module and a battery inspection module; After the charging module balances the voltage of the battery pack for equalization charging, the battery inspection module acquires the internal resistance of the battery monomer before nuclear capacity; After starting the nuclear capacity, the battery pack supplies power to the original load, the DC analog quantity acquisition module acquires the battery pack output current and the bus load current, and the intelligent power monitoring device adjusts the intelligent electronic load value according to the bus load current, so that the battery pack output current remains constant at a set value. When the set battery pack load discharge test end condition is reached, the intelligent power monitoring device obtains the nuclear capacity discharge capacity according to the battery pack discharge current and the discharge time; and after the battery pack load discharge test is completed, the charging module charges the battery pack, the intelligent power monitoring device obtains the nuclear capacity charging capacity according to the charging current and the charging time, and the battery inspection module acquires the internal resistance of the battery monomer after nuclear capacity. The intelligent power monitoring device generates a load discharge nuclear capacity test table according to the internal resistance of the battery monomer before nuclear capacity, the nuclear capacity discharge capacity, the nuclear capacity charging capacity and the internal resistance of the battery monomer after nuclear capacity, so as to complete the nuclear capacity of the battery pack.

[0016] Compared with the prior art, the application has the following advantages: The application provides a substation DC system battery pack load discharge nuclear capacity method and system, which balances the voltage of the battery pack for equalization charging, acquires the internal resistance of the battery monomer before nuclear capacity, adjusts the intelligent electronic load value after starting the nuclear capacity, so that the battery pack output current remains constant at a set value; and charges the battery pack after the battery pack load discharge test is completed, and finally generates a load discharge nuclear capacity test table according to the internal resistance of the battery monomer before nuclear capacity, the nuclear capacity discharge capacity, the nuclear capacity charging capacity and the internal resistance of the battery monomer after nuclear capacity, so as to complete the nuclear capacity of the battery pack. Since the substation DC load changes at different times, the battery discharge current changes, according to the battery characteristics, the battery discharge rate is different, and the battery cutoff voltage is different, so that the battery discharge current remains stable after the intelligent electronic load is used, so that the battery discharge cutoff voltage is in the expected range, and the intelligent electronic load can greatly shorten the nuclear capacity time by adjusting the battery discharge current.

[0017] The application is provided with a backup power supply, which functions as: no matter in the checking discharge or full capacity discharge, during the checking capacity process, there will be a virtual connection of the connecting strip (i.e. poor contact of the wire or connecting strip connecting two batteries) or failure of a single battery in the series battery pack, resulting in that the whole battery cannot be discharged (equivalent to open circuit of the battery pack), if the AC input of the charging module loses power at this time, the relay protection, automatic device and circuit breaker of the whole station will lose power supply, causing the whole station to be powered off. The addition of the backup power supply can avoid the above-mentioned situation, and the substation will not face the risk of losing power of the whole station due to the addition of the checking capacity function, thereby ensuring the reliability of the DC system during the checking capacity.

[0018] Compared with the traditional offline checking capacity method, the DC parallel power supply system and the DC guardian power supply system, the substation DC system battery pack load discharge checking capacity method and system provided by the application can realize the remote online checking capacity function of the substation DC system battery pack, without making the battery pack separate from the bus, thereby effectively reducing the checking capacity workload of the operation and maintenance personnel; the problem of reliability reduction of the whole battery caused by virtual connection of the battery connecting strip or performance reduction of a single battery can be detected; compared with the DC parallel power supply system and the DC guardian power supply system, the modification workload of the DC system is small, the cost is low, and the cost of modifying the traditional series battery pack into the DC parallel power supply system or the DC guardian power supply system can also be effectively reduced.

[0019] The advantages of the additional aspects of the application will be partially given in the following description, partially become obvious from the following description, or be known by the practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only are the embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0021] Figure 1 The substation DC system battery pack load discharge checking capacity method flowchart provided for the embodiment 1 of the application; Figure 2 The substation DC system battery pack load discharge checking capacity system architecture diagram provided for the embodiment 1 of the application. DETAILED DESCRIPTION

[0022] The application will be further described below in combination with the drawings and embodiments.

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. Furthermore, it should be understood that the terms “comprising” and “including”, and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0026] Example 1 like Figure 1 As shown, this embodiment provides a method for online capacity verification of a substation DC system battery pack under load discharge. It is applied to a battery pack consisting of several battery cells connected in series in a substation DC system, and a smart electronic load is connected in parallel on the basis of the original load. Specifically, it includes: After equalizing the battery pack with equalizing voltage, the internal resistance of each battery cell before capacity verification is collected. After the core capacity is activated, the battery pack supplies power to the original load. The output current of the battery pack and the bus load current are collected. The intelligent electronic load value is adjusted according to the bus load current so that the output current of the battery pack remains constant at the set value. When the set conditions for the end of the battery pack load discharge test are met, the core discharge capacity is obtained based on the battery pack discharge current and discharge time; and after the battery pack load discharge test is completed, the battery pack is charged, and the core charging capacity is obtained based on the charging current and charging time, and the internal resistance of the battery cells after the core capacity is obtained is collected after the charging is completed. Based on the internal resistance of individual battery cells before capacity approval, the approved discharge capacity, the approved charging capacity, and the internal resistance of individual battery cells after capacity approval, a load discharge capacity approval test table is generated to complete the capacity approval of the battery pack.

[0027] like Figure 2The substation direct current system battery group load discharging capacity testing system for implementing the above method is shown, which comprises an intelligent power monitoring device, and a parallelly connected charging module, standby power supply, battery group, intelligent electronic load and actual load (i.e. original load, on the basis of which the intelligent electronic load is connected in parallel); wherein, the battery group is connected with a direct current analog quantity acquisition module, insulation monitoring module and battery inspection module.

[0028] The following will be described in combination with Figures 1-2 The method of the embodiment will be described in detail.

[0029] In the embodiment, the process of equalizing charging the battery group at the equalizing voltage comprises: Firstly, the intelligent power monitoring device controls the output voltage of the charging module to be adjusted to the equalizing voltage according to the set value, so that the charging module equalizes charges the battery group at the equalizing voltage.

[0030] The purpose of this step is to eliminate the voltage difference of the single battery and the sulfation by equalizing charging, to compensate for the self-discharge difference, and to restore the overall capacity of the battery group, so that the capacity testing result is more accurate, and after the charging is completed, the intelligent power monitoring device adjusts the output voltage of the charging module to make the battery group in the floating charging state.

[0031] Then, the intelligent power monitoring device controls the battery inspection module to test the internal resistance of the battery single body, which is used as the internal resistance of the battery single body before the capacity testing.

[0032] The purpose of this step is to compare with the internal resistance of the battery single body after the capacity testing, and to test the effect of eliminating the battery sulfation during the capacity testing process.

[0033] Finally, the intelligent direct current power monitoring device controls the output voltage of the charging module to be adjusted to the equalizing voltage according to the set value, so that the charging module equalizes charges the battery group at the equalizing voltage again.

[0034] The purpose of this step is to recharge the battery due to the consumption of the internal power of the battery during the internal resistance testing, to eliminate the voltage difference of the single battery caused by the internal resistance testing, and to make the capacity testing result more accurate.

[0035] In the embodiment, the intelligent power monitoring device controls the output voltage of the charging module to be adjusted according to the set value, so that the output voltage of the charging module is lower than the terminal voltage of the battery group within a set time period, at which time the battery group automatically supplies power to the original load to start the capacity testing.

[0036] Then, the intelligent power monitoring device controls the DC analog quantity acquisition module to collect the output current of the battery pack and the bus load current in real time. Since the DC load of the substation is small, it cannot reach the discharge current required by the existing specifications or regulations. Therefore, the size of the intelligent electronic load is adjusted to keep the output current of the battery at a set value (such as 0.1C 10 A) constant.

[0037] The prior art does not consider that the original load current will change in real time during the capacity verification, so that the battery current also changes. For example, if the first sampling current is 1A and the second sampling current is 20A, the current change in the middle 10 seconds or 50 seconds is not collected, resulting in inaccurate capacity verification capacity.

[0038] The method of the embodiment automatically starts the capacity verification calculation according to the direction and size of the battery current, and the sampling time is in the millisecond level, which is shorter than the sampling time (10-50 seconds) of the prior art. Therefore, the capacity verification result is more accurate.

[0039] Furthermore, the embodiment parallelly connects the intelligent electronic load based on the original load, and adjusts the size of the intelligent electronic load to keep the output current of the battery at a set value (such as 0.1C 10 A) constant.

[0040] Specifically: The DC analog quantity acquisition module collects the bus load current in real time and uploads it to the intelligent power monitoring device through the communication bus to set the output current value (such as 0.1C 10 A) constant.

[0041] The DC load of the substation changes at different times, which can cause the battery discharge current to change. According to the characteristics of the battery, the discharge rate of the battery is different, and the cutoff voltage of the battery is different. After using the intelligent electronic load, the battery discharge current can be kept stable, so that the battery discharge cutoff voltage is within the expected range.

[0042] Taking a 2V lead-acid battery as an example, when the discharge rate I≤0.01C 10 A, the battery cutoff voltage is 1.95V. When 0.55C 10 A<I≤0.65C 10 A, the battery cutoff voltage is 1.65V. Without the technology to stabilize the battery discharge current, the battery cutoff voltage may not be accurate, which can cause the capacity verification process to end prematurely or be delayed, resulting in inaccurate battery capacity calculation.

[0043] In addition, the intelligent electronic load can greatly shorten the run-time by adjusting the battery discharge current. For a 65 Ah battery, the load is generally around 2A or less. Without the electronic load, the run-time is 32 hours, while with the electronic load adjusting the battery discharge current at 0.1C 10 A, the run-time can be shortened to 10 hours or other shorter time.

[0044] In this embodiment, the DC analog acquisition module is used to monitor the battery discharge current and discharge time in real time, and the run-time discharge capacity is calculated. The battery pack terminal voltage and current are recorded every 30 minutes, and are uploaded to the intelligent power monitoring device through RS485 or CAN communication.

[0045] If the battery pack terminal voltage remains higher than the set value or reaches the set discharge capacity (depth of discharge) (for example, if the depth of discharge is 50%, the 100 Ah battery discharge capacity is 50 Ah) within the time period set in the intelligent power monitoring device, it indicates that the battery capacity meets the requirements, and the battery pack load discharge test is ended after the set time is reached. If the battery pack terminal voltage drops below the set value within the set time period, it indicates that the battery capacity does not meet the requirements, and the intelligent power monitoring device sends an alarm signal to prompt the battery operation and maintenance personnel to handle it, and the test is immediately ended.

[0046] In this embodiment, the intelligent power monitoring device sets the discharge depth to 20%, 50%, 80%, and 100%.

[0047] In this embodiment, the intelligent power monitoring device controls the battery patrol module to monitor the battery single voltage in real time. During the test, the battery patrol module collects the battery single voltage in real time and uploads it to the intelligent power monitoring device. If a low battery single voltage alarm occurs, the intelligent power monitoring device stops the test, records the test stop reason, and sends an alarm signal to the background.

[0048] In addition, during the test, if the intelligent power monitoring device detects that the discharge current uploaded by the DC analog acquisition module is zero and the bus voltage drops to the output voltage of the charging module, it is determined that the battery pack is open. At this time, the run-time discharge test is stopped, the output voltage of the charging module is raised, and the battery pack open alarm signal is uploaded to the background for on-site handling of defects by the operation and maintenance personnel.

[0049] In the embodiment, after the battery bank load discharge capacity test is completed, the intelligent electronic load is turned off, the intelligent power supply monitoring output control charging module restores the original battery bank floating and equalizing function, the battery charging current and charging time are calculated in real time through the DC analog quantity acquisition module, the battery bank terminal voltage and current are recorded every 30 minutes, and the RS485 or CAN communication is used to send the intelligent DC power supply monitoring device.

[0050] This step records the battery charging capacity after the battery capacity test is completed. By comparing the battery discharge capacity and the battery charging capacity, the activation effect of the battery capacity test on the battery can be evaluated.

[0051] After the charging is completed, the intelligent power supply monitoring device controls the battery inspection module to test the battery single cell internal resistance, which is used as the battery single cell internal resistance after the capacity test.

[0052] After the battery bank load discharge test is completed, the intelligent power supply monitoring device generates a battery bank load discharge capacity test table by comprehensively considering the battery single cell internal resistance before the capacity test, the discharge capacity, the charging capacity, and the battery single cell internal resistance after the capacity test. The table can be exported through a U disk or sent to the substation background through the IEC61850 protocol, so as to monitor the health status of the battery bank.

[0053] The battery bank load discharge capacity test has a "equalizing charging lockout" function. During the battery bank load discharge test, if the equalizing charging condition is met, the equalizing charging is started after the test is completed. During the equalizing charging of the battery bank, the load discharge test is not allowed to be started.

[0054] In the embodiment, a backup power supply is also connected in parallel, which functions as follows: whether in the verification discharge or the full capacity discharge, during the capacity test, there may be a virtual connection (i.e., poor contact of the wire or connecting strip connecting two batteries) or a single battery failure in the series connected battery bank, which causes the entire battery bank to be unable to discharge (equivalent to an open circuit of the battery bank). If the AC input of the charging module loses power at this time, the relay protection, automatic device, and circuit breaker of the entire station will lose power, causing the entire station to be powered off. The addition of the backup power supply can avoid the above situation, and the station will not face the risk of losing power due to the addition of the capacity test function, thereby ensuring the reliability of the DC system during the capacity test.

[0055] In the embodiment, the insulation monitoring function is to monitor whether the battery has a ground fault caused by battery leakage or other reasons. If there is a ground fault, the capacity test function is not started or stopped. If there is a ground fault, the position of the grounded battery is determined and sent to the background monitoring.

[0056] Compared with the traditional offline capacity checking method, the DC parallel power supply system and the DC guardian power supply system, the on-load discharge capacity checking method of the substation DC system battery pack can realize the remote online capacity checking function of the substation DC system battery pack, does not need to disconnect the battery pack from the bus, effectively reduces the capacity checking workload of the operation and maintenance personnel, can detect the problem of reduced reliability of the whole battery pack caused by the virtual connection of the battery connection strip or the performance degradation of the single battery, has small modification workload and low cost compared with the DC parallel power supply system and the DC guardian power supply system, and can effectively reduce the cost of modifying the traditional series battery pack into the DC parallel power supply system or the DC guardian power supply system.

[0057] Embodiment 2 The embodiment provides an on-load discharge capacity checking system of a substation DC system battery pack, which comprises an intelligent power supply monitoring device, a charging module, a battery pack, an intelligent electronic load and an actual load connected in parallel, the battery pack is composed of a plurality of battery monomers connected in series, and the battery pack is further connected with a DC analog quantity acquisition module and a battery inspection module. After the charging module balances the voltage and charges the battery pack, the battery inspection module acquires the internal resistance of the battery monomer before capacity checking. After starting the capacity checking, the battery pack supplies power to the original load, the DC analog quantity acquisition module acquires the output current of the battery pack and the load current of the bus, and the intelligent power supply monitoring device adjusts the value of the intelligent electronic load according to the load current of the bus, so that the output current of the battery pack remains constant. When the set on-load discharge test end condition of the battery pack is reached, the intelligent power supply monitoring device obtains the capacity checking discharge capacity according to the discharge current and the discharge time of the battery pack; and after the on-load discharge test of the battery pack is completed, the charging module charges the battery pack, the intelligent power supply monitoring device obtains the capacity checking charging capacity according to the charging current and the charging time, and the internal resistance of the battery monomer after capacity checking is acquired by the battery inspection module after the charging is completed. The intelligent power supply monitoring device generates an on-load discharge capacity checking test table according to the internal resistance of the battery monomer before capacity checking, the capacity checking discharge capacity, the capacity checking charging capacity and the internal resistance of the battery monomer after capacity checking, so as to complete the capacity checking of the battery pack.

[0058] It should be noted that the functions of the above system and components correspond to the steps and system composition described in embodiment 1, and the examples and application scenarios realized by the above modules are the same, but are not limited to the content disclosed in the above embodiment 1. It should be noted that the above modules as part of the system can be executed in a computer system such as a set of computer executable instructions.

[0059] The above describes the specific embodiments of the present application in combination with the drawings, but is not a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications or variations made by those skilled in the art on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A method for determining the state of charge of a battery bank of a substation DC system, characterized in that, The application is applied to a battery pack composed of a plurality of battery monomers in series, and parallel intelligent electronic load on the basis of original load; comprising: After the battery pack is balanced charged at the equalizing voltage, the internal resistance of the battery monomer before capacity verification is collected; After starting capacity verification, the battery pack supplies power to the original load, the output current of the battery pack and the bus load current are collected, the intelligent electronic load value is adjusted according to the bus load current, so that the output current of the battery pack remains constant at the set value; When the set battery pack discharge test end condition is reached, the capacity verification discharge capacity is obtained according to the battery pack discharge current and the discharge time; and after the battery pack discharge test ends, the battery pack is charged, the capacity verification charging capacity is obtained according to the charging current and the charging time, and the internal resistance of the battery monomer after capacity verification is collected after charging is completed; The battery pack is verified by generating a load discharge capacity verification test table according to the internal resistance of the battery monomer before capacity verification, the capacity verification discharge capacity, the capacity verification charging capacity and the internal resistance of the battery monomer after capacity verification.

2. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, The process of balancing charging the battery pack at the equalizing voltage includes: controlling the output voltage of the high-voltage adjusting charging module to the equalizing voltage according to the set value, so as to balance charge the battery pack at the equalizing voltage.

3. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, After collecting the internal resistance of the battery monomer before capacity verification, the output voltage of the high-voltage adjusting charging module is controlled to the equalizing voltage according to the set value again, so as to balance charge the battery pack at the equalizing voltage.

4. The method of claim 1, wherein the method further comprises: determining a state of charge of the battery bank; and determining a state of health of the battery bank. The output voltage of the low-voltage adjusting charging module is controlled according to the set value, so that the output voltage of the charging module is lower than the terminal voltage of the battery pack within a set time period, at this time the battery pack supplies power to the original load, and the capacity verification is started.

5. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, If the terminal voltage of the battery pack remains higher than the set value within the set time period, or reaches the set discharge depth, the battery pack discharge test is ended at the same time after the set time is reached; wherein the set discharge depth is set to 20%, 50%, 80% or 100%.

6. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, The process of adjusting the intelligent electronic load value according to the bus load current includes: taking the difference between the output current set value and the bus load current as the current to be consumed by the intelligent electronic load, setting the current to be consumed by the intelligent electronic load to the intelligent electronic load, so that the bus load current is the output current of the battery pack, and the output current set value remains constant.

7. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, The battery pack discharge test has equalizing charging locking function, during the battery pack discharge test, if the equalizing charging condition is met, the equalizing charging is started after the test is ended, and during the equalizing charging process, the battery pack discharge test is not allowed to be started.

8. A method for on-line capacity determination of a battery bank of a substation DC system according to claim 1, characterized in that, The battery pack is also connected with a standby power supply, which avoids the situation that the battery pack cannot be discharged due to the virtual connection of the connecting strip or the failure of the single battery in the battery pack during the capacity verification process.

9. A method of determining the state of charge of a battery bank of a substation DC system according to claim 1, wherein, The battery pack is also connected with an insulation monitoring module for monitoring whether there is a ground fault in the battery pack, if there is, the capacity verification function is not started or stopped, and the position of the grounded battery is determined.

10. A substation DC system battery bank on-load discharge capacity determination system, comprising: Comprising: An intelligent power supply monitoring device, and a charging module, a battery pack, an intelligent electronic load and an actual load connected in parallel, the battery pack is composed of a plurality of battery monomers in series, and the battery pack is also connected with a DC analog quantity collection module and a battery inspection module; After the charging module balances the voltage of the battery pack, the battery inspection module collects the internal resistance of the battery before capacity verification; After the capacity verification is started, the battery pack supplies power to the original load, the DC analog acquisition module collects the output current of the battery pack and the bus load current, and the intelligent power supply monitoring device adjusts the intelligent electronic load value according to the bus load current, so that the output current of the battery pack remains constant at the set value. When the set end condition of the battery pack discharge test is reached, the intelligent power supply monitoring device obtains the capacity verification discharge capacity according to the battery pack discharge current and the discharge time; and after the battery pack discharge test is completed, the charging module charges the battery pack, the intelligent power supply monitoring device obtains the capacity verification charging capacity according to the charging current and the charging time, and collects the internal resistance of the battery after the capacity verification by the battery inspection module. The intelligent power supply monitoring device generates a capacity verification test table with load discharge according to the internal resistance of the battery before the capacity verification, the capacity verification discharge capacity, the capacity verification charging capacity and the internal resistance of the battery after the capacity verification, thereby completing the capacity verification of the battery pack.

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