CN111812525A - Testing device for charging and discharging of modular storage battery and control method thereof - Google Patents

Testing device for charging and discharging of modular storage battery and control method thereof Download PDF

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Publication number
CN111812525A
CN111812525A CN202010566042.7A CN202010566042A CN111812525A CN 111812525 A CN111812525 A CN 111812525A CN 202010566042 A CN202010566042 A CN 202010566042A CN 111812525 A CN111812525 A CN 111812525A
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China
Prior art keywords
converter
current
voltage
converters
storage battery
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CN202010566042.7A
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Chinese (zh)
Inventor
陈忠
杨为
朱太云
柯艳国
施永
朱胜龙
赵恒阳
张国宝
蔡梦怡
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Electric Power Research Institute of State Grid Anhui Electric Power Co Ltd
Hefei University of Technology
State Grid Anhui Electric Power Co Ltd
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Electric Power Research Institute of State Grid Anhui Electric Power Co Ltd
Hefei University of Technology
State Grid Anhui Electric Power Co Ltd
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Priority to CN202010566042.7A priority Critical patent/CN111812525A/en
Publication of CN111812525A publication Critical patent/CN111812525A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/387—Determining ampere-hour charge capacity or SoC
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/385—Arrangements for measuring battery or accumulator variables
    • G01R31/387—Determining ampere-hour charge capacity or SoC
    • G01R31/388—Determining ampere-hour charge capacity or SoC involving voltage measurements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0047—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with monitoring or indicating devices or circuits
    • H02J7/0048—Detection of remaining charge capacity or state of charge [SOC]
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • H02J7/04—Regulation of charging current or voltage
    • H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering

Abstract

The embodiment of the invention provides a testing device for charging and discharging of a modular storage battery and a control method thereof, belonging to the technical field of testing of storage battery packs of transformer substations. The test device includes: one end of the alternating current side transformer is used for being externally connected to alternating current; the alternating current side of the bidirectional AC/DC converter is connected with the other end of the alternating current side transformer; a direct current bus connected to a direct current side of the bidirectional AC/DC converter; the system comprises at least one group of first DC/DC converters, a group of storage battery packs and a control unit, wherein each group of the first DC/DC converters corresponds to one group of storage battery packs and comprises at least two first DC/DC converters; the device comprises at least one second DC/DC converter and an upper computer, wherein the upper computer is connected with the alternating current side transformer, the bidirectional AC/DC converter, the first DC/DC converter and the second DC/DC converter. The testing device and the control method thereof can improve the efficiency and reliability of the system.

Description

Testing device for charging and discharging of modular storage battery and control method thereof
Technical Field
The invention relates to the technical field of testing of a storage battery pack of a transformer substation, in particular to a testing device for charging and discharging of a modular storage battery and a control method thereof.
Background
The storage battery pack is an indispensable device in a direct-current power supply system of a transformer substation, and when the alternating-current power supply system of the transformer substation breaks down, the storage battery pack is required to be used for providing continuous power supply for loads such as relay protection, automatic devices, communication and illumination, so that equipment can continue to operate normally, and the transformer substation can be guaranteed to be safe for passing the fault period. The capacity that storage battery group can discharge in fact directly determines the continuous power supply ability of direct current electrical power generating system, therefore before the new storage battery group of transformer substation is put into operation, need to extract a certain proportion of single section battery and carry out the heavy current and accelerate the capacity test. The traditional checking test or activation test device for the capacity of the single storage battery has small capacity, is difficult to meet the special requirement of a large-current test, adopts energy-consuming equipment more, has long test time one by one, and is easy to cause electric energy waste after multiple tests.
Disclosure of Invention
The invention aims to provide a testing device for charging and discharging a modular storage battery and a control method thereof, wherein the testing device and the control method thereof can realize large-current charging and discharging so as to improve the efficiency and reliability of a system.
In order to achieve the above object, an embodiment of the present invention provides a testing apparatus for charging and discharging a modular battery, the testing apparatus including:
one end of the alternating current side transformer is used for being externally connected to alternating current;
the alternating current side of the bidirectional AC/DC converter is connected with the other end of the alternating current side transformer;
a direct current bus connected to a direct current side of the bidirectional AC/DC converter;
the first end of each first DC/DC converter is connected with a positive phase line of the direct current bus, the second end of each first DC/DC converter is connected with a negative phase line of the direct current bus, the third ends of the first DC/DC converters are connected with each other and with the positive pole of the corresponding storage battery pack, the fourth ends of the first DC/DC converters are connected with each other and with the negative pole of the corresponding storage battery pack, and the fifth ends of the first DC/DC converters are connected with each other through a communication line; and
each second DC/DC converter is correspondingly provided with a group of storage battery packs, the first end of each second DC/DC converter is connected with the positive phase line of the direct-current bus, the second end of each second DC/DC converter is connected with the negative phase line of the direct-current bus, the third end of each second DC/DC converter is connected with the positive pole of the corresponding storage battery pack, the fourth end of each second DC/DC converter is connected with the negative pole of the corresponding storage battery pack, and the fifth end of each second DC/DC converter is connected with the communication line; and
and the upper computer is connected with the alternating current side transformer, the bidirectional AC/DC converter, the first DC/DC converter and the second DC/DC converter.
Optionally, the first DC/DC converter and the second DC/DC converter include:
the DC/DC main circuit is provided with a first end connected with a positive phase line of the direct current bus, a second end connected with a negative phase line of the direct current bus, a third end connected with the positive electrode of the storage battery pack, and a fourth end connected with the negative electrode of the storage battery pack;
the voltage and current sampling circuit is connected with the fifth end of the DC/DC main circuit and is used for collecting the current/voltage of the DC/DC main circuit;
the driving circuit is connected with the sixth end of the DC/DC main circuit and is used for driving the DC/DC main circuit;
and the control circuit is connected with the voltage and current sampling circuit and the driving circuit and is used for controlling the work of the voltage and current sampling circuit and the driving circuit.
Alternatively,
the control circuit includes:
the control module is connected with the voltage and current sampling circuit and used for receiving a sampling signal;
a secondary current adjusting circuit for performing a secondary adjusting operation on the current of the secondary battery pack;
one end of the droop control module is connected with the secondary current adjusting circuit;
a voltage ring;
a mode selection switch, wherein a first end is connected with the control module, a second end is connected with the droop control module, and a third end is connected with the voltage ring;
one end of the current loop is connected with the mode selection switch; and
and one end of the PWM module is connected with the current loop, and the other end of the PWM module is connected with the driving circuit.
In another aspect, the present invention further provides a method for controlling charging and discharging of a modular battery, the method for controlling the testing apparatus described in any one of the above, the method comprising:
the upper computer acquires a voltage value or an SOC value of each storage battery pack through the first DC/DC converter or the second DC/DC converter;
dividing the storage battery into a charging group and a discharging group according to the magnitude relation of a voltage value or an SOC value;
executing a charging instruction on the storage battery pack of the charging group and executing a discharging instruction on the storage battery pack of the discharging group;
determining the sequence of the completion of the charging instruction and the discharging instruction;
under the condition that the charging instruction is completed firstly, controlling an alternating current side transformer and a bidirectional DC/DC converter to feed back electric power to an external alternating current power grid;
and under the condition that the discharge command is completed firstly, controlling the alternating current side transformer and the bidirectional DC/DC converter to obtain power from an external alternating current power grid.
Optionally, the executing the charging instruction on the storage battery pack of the charging group specifically includes:
selecting a first DC/DC converter or a group of second DC/DC converters as a main DC/DC converter by a competition mechanism by adopting a master-slave droop control method;
the main DC/DC converter measures the voltage of the storage battery pack;
judging whether the storage battery pack is in a full-power state or not according to the voltage;
determining the current charging mode according to the voltage under the condition that the storage battery pack is judged not to be in a full-charge state;
and sending a standby instruction to the rest of the DC/DC converters when the charging mode is the constant voltage mode, and executing a program corresponding to the constant voltage mode by the main DC/DC converter.
Optionally, the executing the charging instruction on the storage battery pack of the charging group specifically includes:
under the condition that the charging mode is a constant current mode, calculating the number of the DC/DC converters needing to participate in the work;
selecting the number of DC/DC converters as the DC/DC converters participating in work;
and sending a working instruction to the DC/DC converter which participates in the working so as to execute a program corresponding to the constant current mode, and sending a standby instruction to the rest of the DC/DC converters.
Optionally, the executing the discharge instruction on the storage battery pack of the discharge group specifically includes:
selecting a first DC/DC converter or a group of second DC/DC converters as a main DC/DC converter by a competition mechanism by adopting a master-slave droop control method;
the main DC/DC converter measures the voltage of the storage battery pack;
judging whether the discharging instruction is finished or not according to the voltage;
under the condition that the discharging instruction is not completed, calculating the number of the DC/DC converters needing to participate in the work;
selecting the number of DC/DC converters as the DC/DC converters participating in work;
and sending a working instruction to the DC/DC converter participating in the working so as to execute a program corresponding to the discharging instruction, and sending a standby instruction to the rest of the DC/DC converters.
Optionally, the calculating the number of the DC/DC converters required to participate in the operation specifically includes:
the number is calculated according to equation (1),
Figure BDA0002547669310000041
wherein n is the number, IrefTo carry out the discharge current of the battery pack in the constant current moderateIs the maximum current that the DC/DC converter can load.
Optionally, the determining the current charging mode according to the voltage specifically includes:
determining that the mode is a constant voltage mode when the voltage is greater than or equal to a first preset value;
and determining that the mode is a constant current mode under the condition that the voltage is less than or equal to a second preset value, wherein the second preset value is less than the first preset value.
In yet another aspect, the present invention also provides a storage medium storing instructions for reading by a machine to cause the machine to perform the control method as described in any one of the above.
Through the technical scheme, the testing device and the control method for charging and discharging of the modular storage battery realize the large-current charging and discharging operation of the storage battery pack and improve the efficiency and the reliability of a system by adopting a mode of connecting a plurality of DC/DC converters in parallel. In addition, when the main DC/DC converter is damaged, the testing device can generate a new main DC/DC converter again through a competition mechanism so as to continue to complete the work; when the communication line has a fault, the interior of the DC/DC converter of each storage battery pack adopts droop control and is provided with a complete control circuit, so that the charging and discharging operations can be continuously finished respectively.
Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the embodiments of the invention without limiting the embodiments of the invention. In the drawings:
FIG. 1 is a schematic diagram of a modular battery charge and discharge testing apparatus according to one embodiment of the present invention;
fig. 2 is a diagram of a connection relationship between a DC/DC converter and a corresponding battery pack according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a DC/DC converter according to one embodiment of the present invention;
FIG. 4 is a flow chart of a method of controlling charging and discharging of a modular battery according to one embodiment of the present invention;
FIG. 5 is a flow diagram of a charging instruction according to one embodiment of the invention;
fig. 6 is a schematic diagram of a switching method of a constant voltage mode and a constant current mode according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a droop control module according to one embodiment of the present invention;
FIG. 8 is a schematic diagram of a secondary current adjustment module according to one embodiment of the invention; and
FIG. 9 is a flow diagram of a discharge instruction according to one embodiment of the invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
In the embodiments of the present invention, unless otherwise specified, the use of directional terms such as "upper, lower, top, and bottom" is generally used with respect to the orientation shown in the drawings or the positional relationship of the components with respect to each other in the vertical, or gravitational direction.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between the various embodiments can be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not be within the protection scope of the present invention.
Fig. 1 is a schematic diagram of a testing device for charging and discharging a modular battery according to an embodiment of the present invention. In fig. 1, the testing apparatus may include an AC-side transformer 10, a bidirectional AC/DC converter 20, a DC bus 30, at least one set of first DC/DC converters 40, at least one second DC/DC converter 50, and an upper computer (not shown in fig. 1). One end of the ac-side transformer 10 may be used for external connection to an ac power. The AC side of the bi-directional AC/DC converter 20 may be used to connect to the other end of the AC side transformer 10. The DC bus 30 may be connected to the DC side of the bi-directional AC/DC converter 20. Each set of first DC/DC converters 40 may correspond to at least one battery pack B, and includes at least two first DC/DC converters 40, a first end of each first DC/DC converter 40 may be connected to a positive phase line of the DC bus 30, a second end may be connected to a negative phase line of the DC bus 30, a third end may be connected to each other and to a positive electrode of the corresponding battery pack B, a fourth end may be connected to each other and to a negative electrode of the corresponding battery pack B, and a fifth end (communication interface) may be connected to each other through a communication line. Fig. 1 shows a state where only one battery pack B corresponds to two first DC/DC converters 40. In the case where the number of the first DC/DC converters 40 is greater than 2, the connection manner thereof may be as shown in fig. 2. Each second DC/DC converter 50 may correspond to a group of battery packs, a first terminal of each second DC/DC converter 50 may be connected to a positive phase line of the DC bus, a second terminal may be connected to a negative phase line of the DC bus 30, a third terminal may be connected to a positive electrode of the corresponding battery pack B, a fourth terminal may be connected to a negative electrode of the corresponding battery pack B, and a fifth terminal may be connected to a communication line. The upper computer may be connected to the AC-side transformer 10, the bidirectional AC/DC converter 20, the first DC/DC converter 40, and the second DC/DC converter 50.
Here, the first DC/DC converter 40 and the second DC/DC converter 50 may have the same structure.
In this embodiment, for battery pack B requiring large current charging and discharging, a plurality of DC/DC converters may be connected in parallel to connect battery pack B to DC bus 30, that is, to connect first DC/DC converter 40. On the other hand, for battery pack B that is not required to perform large-current charging and discharging, it is possible to connect battery pack B to DC bus 30, i.e., the connection of second DC/DC converter 50, in such a manner that a single DC/DC converter is directly connected.
The specific structure of the DC/DC converter (the first DC/DC converter 40 or the second DC/DC converter 50) may be various types known to those skilled in the art. In one embodiment of the present invention, as shown in fig. 3, the DC/DC converter may include a DC/DC main circuit 41, a voltage current sampling circuit 42, a driving circuit 43, and a control circuit 44. The DC/DC main circuit 41 can be configured to perform DC-to-DC (direct current-to-direct current) operation, and has a first end connected to the positive phase line of the DC bus 30, a second end connected to the negative phase line of the DC bus 30, a third end connected to the positive electrode of the battery B, and a fourth end connected to the negative electrode of the battery B. The voltage/current sampling circuit 42 may be connected to a fifth terminal of the DC/DC main circuit 41, and is configured to collect current/voltage (sampling signal) of the DC/DC main circuit 41. The driving circuit 43 may be connected to a sixth terminal of the DC/DC main circuit 41 for driving the DC/DC main circuit 41. The control circuit 44 may be connected to the voltage-current sampling circuit 42 and the driving circuit 43, and is used for controlling the operations of the voltage-current sampling circuit 42 and the driving circuit 43.
In this embodiment, the specific structure of the control circuit 44 may be various types known to those skilled in the art. In one embodiment of the present invention, as shown in fig. 3, the control circuit 44 may include a control module 44A, a secondary current adjusting circuit 44B, a droop control module 44C, a voltage loop 44D, a current loop 44E, a mode selection switch 44G, and a PWM modulation module 44F. The control module 44A may be connected to the voltage-current sampling circuit 42, and is configured to receive the sampling signal collected by the voltage-current sampling circuit 42. Secondary current adjustment circuit 44B may be used to perform a secondary adjustment operation on the current of battery pack B. One end of the droop control module 44C may be connected to the secondary current adjustment circuit 44B for performing droop control operations. The mode selection switch 44G may have a first terminal connected to the control module 44A, a second terminal connected to the droop control module 44C, and a third terminal connected to the voltage loop 44D for switching the connection between the current loop 44E and the droop control module 44C and the voltage loop 44D, thereby performing a mode switching operation. One end of the current loop 44E may be connected to the mode selection switch G. One end of the PWM modulation module 44F may be connected to the current loop 44E, and the other end may be connected to the driving circuit 43, for performing a modulation operation of the PWM signal.
On the other hand, the above-mentioned modular battery charging and discharging test device can work in various ways known to those skilled in the art. In this embodiment of the present invention, there is also provided a control method for charging and discharging a modular battery, the control method being used for controlling the testing apparatus as described in any one of the above. As shown in fig. 4, the control method may include:
in step S10, the upper computer acquires a voltage value or an SOC value of each battery pack through the first DC/DC converter 40 or the second DC/DC converter 50;
in step S11, battery B is divided into a charging bank and a discharging bank according to the magnitude relationship of the voltage value or the SOC value. Specifically, in this embodiment, the battery packs B may be arranged in order of, for example, a voltage value from large to small, and then the first half of the battery packs B may be selected as the discharge pack, and the remaining battery packs B may be selected as the charge pack. In addition, when the number of battery packs B is odd, battery packs B positioned in the middle may be directly placed in the discharging bank or the charging bank.
In step S12, a charge command is executed for battery pack B of the charge group, and a discharge command is executed for battery pack B of the discharge group. In this embodiment, the charge command or the discharge command may be in various forms known to those skilled in the art. In one example of the present invention, the charging instruction may be, for example, as shown in fig. 5. In fig. 5, the charging instruction may include:
in step S20, a master-slave droop control method is used to select one first DC/DC converter 40 or one group of second DC/DC converters 50 as the master DC/DC converter through a contention mechanism.
In step S20, main DC/DC converter 40 measures the voltage of battery pack B.
In step S21, it is determined whether battery pack B is in a full charge state based on the detected voltage.
In step S22, when it is determined that battery pack B is not in a fully charged state, the current charging mode is determined based on the detected voltage. In this embodiment, the fact that battery pack B is not in a fully charged state means that a charge command can be executed at this time, and therefore the current charging mode can be further determined based on the voltage of battery pack B. Wherein the specific manner of determining the pattern can be in a variety of forms known to those skilled in the art. Taking a conventional operation in the prior art as an example, the specific manner may be, for example, presetting a threshold voltage, and when the voltage of the battery pack B is lower than the threshold voltage, entering a constant current mode, so that the voltage of the battery pack B is raised; when the voltage of the battery pack B is higher than the threshold voltage, a constant voltage mode is entered, so that the voltage of the battery pack B is kept constant. However, the voltage collected by the current-voltage sampling circuit has a certain error, and the voltage value fed back finally is a fluctuation value. This voltage, if fluctuating around the threshold voltage, can cause the test device to switch repeatedly between constant voltage and constant current modes, causing the test device to malfunction. Therefore, in a preferred example of the present invention, the specific manner may also be, for example, presetting the first preset value V1 and the second preset value V2, wherein the first preset value V1 is greater than the second preset value V2. Entering a constant voltage mode in case the voltage is greater than a first preset value V1; when the voltage is smaller than the second preset value V2, the constant current mode is entered, and the schematic diagram is shown in fig. 6, so that the problem of repeated switching of the two modes due to voltage fluctuation can be well avoided.
In step S23, when the charging mode is the constant voltage mode, a standby command is transmitted to the remaining DC/DC converters (the first DC/DC converter 40 or the second DC/DC converter 50), and the main DC/DC converter executes a program corresponding to the constant voltage mode. In this embodiment, the program corresponding to the constant voltage mode may be in various forms known to those skilled in the art. In addition, in controlling the test apparatus to execute the procedure of the constant voltage mode, it may be that the mode switching switch 44G is controlled to connect the voltage ring 44D to the current ring 44E, so that the voltage ring 44D and the current ring 44E can cooperate to complete the charging operation in the constant voltage mode.
In step S24, in the case where the charging mode is the constant current mode, the number of DC/DC converters that need to participate in the operation is calculated. In this embodiment, the specific manner of calculating the number of DC/DC converters 40 that need to participate in the constant current mode may be in various forms known to those skilled in the art. Taking a conventional calculation manner in the prior art as an example, the specific manner may be, for example, directly and randomly selecting a plurality of DC/DC converters 40. In a preferred example of the invention, the requirements of energy saving and high efficiency of the device are taken into account, and the maximum current which can be loaded exists in each DC/DC converter is also taken into account. Then, the specific way may be to calculate the number according to formula (1),
Figure BDA0002547669310000101
wherein n is the number, IrefTo perform the procedure of the constant current mode, discharge current, I, of battery BrateIs the maximum current that the DC/DC converter can load. Further, when the calculated number of the DC/DC converters is larger than the number of the test apparatuses actually existing, it indicates that the charging command cannot be completed, and the operation can be stopped immediately, thereby avoiding damage to the DC/DC converters.
In step S25, the calculated number of DC/DC converters is selected as the DC/DC converters participating in the operation. In this embodiment, the program corresponding to the constant current mode may be in various forms known to those skilled in the art. In the embodiment of the present invention, when controlling the testing apparatus to execute the constant current mode program, it may be that the control mode switch 44G connects the droop control module 44C to the current loop 44E, so that the secondary current adjusting circuit 44B, the droop control module 44C and the current loop 44E can cooperate to complete the charging operation in the constant current mode. When the droop control module 44C and the secondary current adjustment circuit 44B operate, the droop control module 44C changes the slope of the external characteristic of the DC/DC converter corresponding to the battery pack B, thereby equalizing the load current. Specifically, the external characteristics of the single DC/DC converter can be expressed by equation (2),
U＝Uo-MI， (2)
wherein, U is the output voltage of the single DC/DC converter, Uo is the output voltage of the single DC/DC converter during no-load, M is the droop coefficient, and I is the current output by the single DC/DC converter. The control schematic diagram may be as shown in fig. 7. In the secondary current adjusting circuit 44B, during operation, a difference (Δ I) between the actual current and the set current may be calculated by trial, an adjustment amount required for the voltage reference value to maintain the current constant is calculated by the droop coefficient, and the voltage reference value (Uo + Δ U) in the droop control is adjusted, so that the current is maintained constant. The schematic diagram is shown in fig. 8.
In step S26, an operation command is sent to the DC/DC converters involved in the operation to execute the program corresponding to the constant current mode, and a standby command is sent to the remaining DC/DC converters.
Similarly, for the discharge instruction, the steps shown in fig. 9, for example, may be included. In fig. 9, the discharge command may include:
in step S30, a master-slave droop control method is used to select one of the first DC/DC converter 40 or the second DC/DC converter 50 as the master DC/DC converter through a contention mechanism.
In step S31, the main DC/DC converter measures the voltage of the battery pack.
In step S32, it is determined whether the discharge command is completed based on the measured voltage;
in step S33, in the case where the discharge command is not completed, the number of DC/DC converters that need to participate in the operation is calculated. In this embodiment, the specific manner of calculating the number of DC/DC converters that need to participate in the operation may be in various forms known to those skilled in the art. Taking a conventional calculation manner in the prior art as an example, the specific manner may be, for example, directly and randomly selecting a plurality of DC/DC converters. In a preferred example of the invention, the requirements of energy saving and high efficiency of the device are taken into account, and the maximum current which can be loaded exists in each DC/DC converter is also taken into account. Then, the specific way may be to calculate the number according to formula (1),
Figure BDA0002547669310000121
wherein n is the number, IrefTo perform the procedure of the constant current mode, discharge current, I, of battery BrateIs the maximum current that the DC/DC converter can load. Further, when the calculated number of the DC/DC converters is larger than the number of the test apparatuses actually existing, it indicates that the charging command cannot be completed, and the operation can be stopped immediately, thereby avoiding damage to the DC/DC converters.
In step S34, the calculated number of DC/DC converters 40 is selected as the DC/DC converters participating in the operation. In this embodiment, the program corresponding to the discharge command may be in various forms known to those skilled in the art. In the embodiment of the present invention, when the test apparatus is controlled to execute the constant current mode program, the control mode switch 44G may connect the droop control module 44C to the current loop 44E, so that the secondary current adjusting circuit 44B, the droop control module 44C and the current loop 44E can cooperate to complete the discharging operation under the discharging command. When the droop control module 44C and the secondary current adjustment circuit 44B operate, the droop control module 44C changes the slope of the external characteristic of the DC/DC converter corresponding to the battery pack B, thereby equalizing the load current. Specifically, the external characteristics of the single DC/DC converter 40 can be expressed by equation (2),
U＝Uo-MI， (2)
where U is the output voltage of the single DC/DC converter 40, Uo is the output voltage of the single DC/DC converter 40 during no-load, M is the droop coefficient, and I is the current output by the single DC/DC converter 40. The control schematic diagram may be as shown in fig. 7. In the secondary current adjusting circuit 44B, during operation, a difference (Δ I) between the actual current and the set current may be calculated by trial, an adjustment amount required for the voltage reference value to maintain the current constant is calculated by the droop coefficient, and the voltage reference value (Uo + Δ U) in the droop control is adjusted, so that the current is maintained constant. The schematic diagram is shown in fig. 8.
In step S35, an operation command is sent to the DC/DC converters participating in the operation to execute a program corresponding to the discharge command, and a standby command is sent to the remaining DC/DC converters.
In step S13, determining the order of completion of the charging command and the discharging command;
in step S14, in the case where the charging command is completed first, the ac-side transformer 10 and the bidirectional DC/DC converter are controlled to feed back electric power to the external ac grid;
in step S15, when the discharge command is completed first, the ac-side transformer 10 and the bidirectional DC/DC converter are controlled to obtain electric power from the external ac power grid.
In this embodiment, in the prior art, the battery pack B is charged and discharged directly or consumed directly by a discharge resistor, which results in a large amount of power waste during the test. For the technical problem, in the case that the electric quantity is excessive, the electric power is fed back to the external ac power grid in the steps S14 to S15, and in the case that the electric quantity is insufficient, the electric power is obtained from the external ac power grid, so that the waste of the electric power is well avoided, and the energy is saved.
In yet another aspect, the present invention also provides a storage medium which may store instructions which can be used to be read by a machine to cause the machine to perform the control method as any one of the above. The storage medium may be, but is not limited to, various media that can store program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk, which are known to those skilled in the art.
Through the technical scheme, the testing device and the control method for charging and discharging of the modular storage battery realize the large-current charging and discharging operation of the storage battery pack B by adopting a mode of connecting a plurality of DC/DC converters in parallel, and improve the efficiency and the reliability of a system. In addition, when the main DC/DC converter is damaged, the testing device can also generate a new main DC/DC converter again through a competition mechanism so as to continue to complete the work; when the communication line has a fault, the interior of the DC/DC converter of each storage battery pack adopts droop control and is provided with a complete control circuit, so that the charging and discharging operations can be continuously finished respectively.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solution of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications all belong to the protection scope of the embodiments of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention will not be described separately for the various possible combinations.
Those skilled in the art can understand that all or part of the steps in the method for implementing the above embodiments may be implemented by a program to instruct related hardware, where the program is stored in a storage medium and includes several instructions to enable a (may be a single chip, a chip, etc.) or a processor (processor) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
In addition, various different embodiments of the present invention may be arbitrarily combined with each other, and the embodiments of the present invention should be considered as disclosed in the disclosure of the embodiments of the present invention as long as the embodiments do not depart from the spirit of the embodiments of the present invention.

Claims (10)

1. A testing device for charging and discharging a modular storage battery is characterized by comprising:
one end of the alternating current side transformer is used for being externally connected to alternating current;
the alternating current side of the bidirectional AC/DC converter is connected with the other end of the alternating current side transformer;
a direct current bus connected to a direct current side of the bidirectional AC/DC converter;
the first end of each first DC/DC converter is connected with a positive phase line of the direct current bus, the second end of each first DC/DC converter is connected with a negative phase line of the direct current bus, the third ends of the first DC/DC converters are connected with each other and with the positive pole of the corresponding storage battery pack, the fourth ends of the first DC/DC converters are connected with each other and with the negative pole of the corresponding storage battery pack, and the fifth ends of the first DC/DC converters are connected with each other through a communication line; and
each second DC/DC converter is correspondingly provided with a group of storage battery packs, the first end of each second DC/DC converter is connected with the positive phase line of the direct-current bus, the second end of each second DC/DC converter is connected with the negative phase line of the direct-current bus, the third end of each second DC/DC converter is connected with the positive pole of the corresponding storage battery pack, the fourth end of each second DC/DC converter is connected with the negative pole of the corresponding storage battery pack, and the fifth end of each second DC/DC converter is connected with the communication line; and
and the upper computer is connected with the alternating current side transformer, the bidirectional AC/DC converter, the first DC/DC converter and the second DC/DC converter.
2. The test apparatus of claim 1, wherein the first DC/DC converter and the second DC/DC converter comprise:
the DC/DC main circuit is provided with a first end connected with a positive phase line of the direct current bus, a second end connected with a negative phase line of the direct current bus, a third end connected with the positive electrode of the storage battery pack, and a fourth end connected with the negative electrode of the storage battery pack;
the voltage and current sampling circuit is connected with the fifth end of the DC/DC main circuit and is used for collecting the current/voltage of the DC/DC main circuit;
the driving circuit is connected with the sixth end of the DC/DC main circuit and is used for driving the DC/DC main circuit;
and the control circuit is connected with the voltage and current sampling circuit and the driving circuit and is used for controlling the work of the voltage and current sampling circuit and the driving circuit.
3. The test device of claim 2, wherein the control circuit comprises:
the control module is connected with the voltage and current sampling circuit and used for receiving a sampling signal;
a secondary current adjusting circuit for performing a secondary adjusting operation on the current of the secondary battery pack;
one end of the droop control module is connected with the secondary current adjusting circuit;
a voltage ring;
a mode selection switch, wherein a first end is connected with the control module, a second end is connected with the droop control module, and a third end is connected with the voltage ring;
one end of the current loop is connected with the mode selection switch; and
and one end of the PWM module is connected with the current loop, and the other end of the PWM module is connected with the driving circuit.
4. A control method of charging and discharging a modular battery, the control method being used for controlling the test device according to any one of claims 1 to 3, the control method comprising:
the upper computer acquires a voltage value or an SOC value of each storage battery pack through the first DC/DC converter or the second DC/DC converter;
dividing the storage battery into a charging group and a discharging group according to the magnitude relation of a voltage value or an SOC value;
executing a charging instruction on the storage battery pack of the charging group and executing a discharging instruction on the storage battery pack of the discharging group;
determining the sequence of the completion of the charging instruction and the discharging instruction;
under the condition that the charging instruction is completed firstly, controlling an alternating current side transformer and a bidirectional DC/DC converter to feed back electric power to an external alternating current power grid;
and under the condition that the discharge command is completed firstly, controlling the alternating current side transformer and the bidirectional DC/DC converter to obtain power from an external alternating current power grid.
5. The control method according to claim 4, wherein the executing of the charging instruction on the battery packs of the charging group specifically comprises:
selecting a first DC/DC converter or a group of second DC/DC converters as a main DC/DC converter by a competition mechanism by adopting a master-slave droop control method;
the main DC/DC converter measures the voltage of the storage battery pack;
judging whether the storage battery pack is in a full-power state or not according to the voltage;
determining the current charging mode according to the voltage under the condition that the storage battery pack is judged not to be in a full-charge state;
and sending a standby instruction to the rest of the DC/DC converters when the charging mode is the constant voltage mode, and executing a program corresponding to the constant voltage mode by the main DC/DC converter.
6. The control method according to claim 5, wherein the executing of the charging instruction on the battery packs of the charging group specifically comprises:
under the condition that the charging mode is a constant current mode, calculating the number of the DC/DC converters needing to participate in the work;
selecting the number of DC/DC converters as the DC/DC converters participating in work;
and sending a working instruction to the DC/DC converter which participates in the working so as to execute a program corresponding to the constant current mode, and sending a standby instruction to the rest of the DC/DC converters.
7. The control method according to claim 4, wherein the executing of the discharge command on the battery pack of the discharge bank specifically comprises:
selecting a first DC/DC converter or a group of second DC/DC converters as a main DC/DC converter by a competition mechanism by adopting a master-slave droop control method;
the main DC/DC converter measures the voltage of the storage battery pack;
judging whether the discharging instruction is finished or not according to the voltage;
under the condition that the discharging instruction is not completed, calculating the number of the DC/DC converters needing to participate in the work;
selecting the number of DC/DC converters as the DC/DC converters participating in work;
and sending a working instruction to the DC/DC converter participating in the working so as to execute a program corresponding to the discharging instruction, and sending a standby instruction to the rest of the DC/DC converters.
8. The control method according to claim 5 or 6, wherein calculating the number of the DC/DC converters that need to participate in the operation specifically comprises:
the number is calculated according to equation (1),
Figure FDA0002547669300000041
wherein n is the number, IrefTo carry out the discharge current of the battery pack in the constant current moderateIs the maximum current that the DC/DC converter can load.
9. The control method according to claim 5, wherein the determining a current charging mode according to the voltage specifically comprises:
determining that the mode is a constant voltage mode when the voltage is greater than or equal to a first preset value;
and determining that the mode is a constant current mode under the condition that the voltage is less than or equal to a second preset value, wherein the second preset value is less than the first preset value.
10. A storage medium storing instructions for reading by a machine to cause the machine to perform a control method according to any one of claims 4 to 9.
CN202010566042.7A 2020-06-19 2020-06-19 Testing device for charging and discharging of modular storage battery and control method thereof Pending CN111812525A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114024440A (en) * 2021-11-18 2022-02-08 深圳国氢新能源科技有限公司 Method, device, equipment and storage medium for controlling fuel cell DC/DC converter
CN115663978A (en) * 2022-12-13 2023-01-31 麦田能源有限公司 Battery energy storage power supply system, and voltage balancing method and device of battery pack
WO2023114303A1 (en) * 2021-12-15 2023-06-22 Raytheon Company Multi slope output impedance controller to reduce current imbalance in a masterless configuration of n parallel-connected power converters and improve load regulation in a single power converter

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114024440A (en) * 2021-11-18 2022-02-08 深圳国氢新能源科技有限公司 Method, device, equipment and storage medium for controlling fuel cell DC/DC converter
WO2023114303A1 (en) * 2021-12-15 2023-06-22 Raytheon Company Multi slope output impedance controller to reduce current imbalance in a masterless configuration of n parallel-connected power converters and improve load regulation in a single power converter
CN115663978A (en) * 2022-12-13 2023-01-31 麦田能源有限公司 Battery energy storage power supply system, and voltage balancing method and device of battery pack
CN115663978B (en) * 2022-12-13 2023-04-07 麦田能源有限公司 Battery energy storage power supply system, and voltage balancing method and device of battery pack

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