CN114006391A - Medium-voltage direct-hanging energy storage converter system and start-stop control method thereof - Google Patents
Medium-voltage direct-hanging energy storage converter system and start-stop control method thereof Download PDFInfo
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- CN114006391A CN114006391A CN202111279538.7A CN202111279538A CN114006391A CN 114006391 A CN114006391 A CN 114006391A CN 202111279538 A CN202111279538 A CN 202111279538A CN 114006391 A CN114006391 A CN 114006391A
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- 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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
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Abstract
The application discloses middling pressure straightly-hung energy storage converter system and start-stop control method thereof includes: the high-voltage alternating current device is electrically connected with an alternating current power grid, and the low-voltage direct current device is electrically connected with an energy storage end; the high-voltage alternating-current device is in a three-phase star connection mode, each phase is formed by connecting double H-bridge power modules in series, and the low-voltage direct-current device is formed by connecting single H-bridge power modules in parallel. The high-voltage alternating-current device and the low-voltage direct-current device are different in module number and high in flexibility by adopting a common high-frequency bus structure, and compared with a chain structure, the high-voltage alternating-current device and the low-voltage direct-current device save the number of devices of a converter and an electric energy conversion link, reduce the cost and improve the conversion efficiency. The high-voltage power grid can be directly hung without a power frequency transformer, and the requirement of quick power response can be realized.
Description
Technical Field
The application relates to the technical field, in particular to a medium-voltage direct-hanging energy storage converter system and a start-stop control method thereof.
Background
The energy storage converter is an important component of an energy storage system and plays roles in alternating current and direct current conversion and power bidirectional transmission between a battery and an alternating current power grid.
The current energy storage device mainly has the following two structures: firstly), the energy storage device is connected to a power grid through a power frequency transformer, and the structure has a series of problems of low efficiency, large volume, high cost and the like; two) chain and MMC structures, wherein MMC structures have certain disadvantages compared with chain structures in terms of complexity, cost, etc. The chain-type structure energy storage device mostly adopts a chain-type H bridge direct-hanging battery pack, or the chain-type H bridge is connected with the battery pack through a DC/DC converter, and the chain-type structure energy storage device has the advantages of simple structure, more components and electric energy conversion links of a converter, difficult efficiency improvement and higher cost; meanwhile, since the charge and discharge power of the battery cannot be effectively controlled, the life of the battery is reduced.
Switch, module quantity are numerous among the energy memory, and each equipment opens and stops the time control loaded down with trivial details and have certain logic sequence, and the maloperation can bring more potential safety hazard, is unfavorable for energy storage system's steady operation.
Disclosure of Invention
In order to solve the technical problems, the following technical scheme is provided:
in a first aspect, an embodiment of the present application provides a medium-voltage direct-hanging energy storage converter system, including: the high-voltage alternating current device is electrically connected with an alternating current power grid, and the low-voltage direct current device is electrically connected with an energy storage end; the high-voltage alternating-current device is in a three-phase star connection mode, each phase is formed by connecting double H-bridge power modules in series, and the low-voltage direct-current device is formed by connecting single H-bridge power modules in parallel.
By adopting the implementation mode, the common high-frequency bus structure is adopted, the numbers of the modules of the high-voltage alternating-current device and the low-voltage direct-current device are different, the flexibility is high, compared with a chain structure, the number of devices of the converter and the electric energy conversion link are saved, the cost is reduced, and the conversion efficiency is improved. The high-voltage power grid can be directly hung without a power frequency transformer, and the requirement of quick power response can be realized.
With reference to the first aspect, in a first possible implementation manner of the first aspect, the dual H-bridge power module includes a low-frequency H-bridge, a first dc capacitor, and a first high-frequency H-bridge, where the low-frequency H-bridge, the first dc capacitor, and the first high-frequency H-bridge are connected in parallel, an input end of the low-frequency H-bridge is electrically connected to an ac power grid, an output end of the first high-frequency H-bridge is electrically connected to an input end of a first high-frequency transformer, and an output end of the first high-frequency transformer is electrically connected to the single H-bridge power module.
With reference to the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the single H-bridge power module includes a second high-frequency H-bridge and a second dc capacitor, the second high-frequency H-bridge and the second dc capacitor are connected in parallel, an input end of the second high-frequency H-bridge is electrically connected to an output end of a second high-frequency transformer, and an input end of the second high-frequency transformer is electrically connected to an output end of the first high-frequency transformer.
In combination with the first aspect or the first or second possible implementation manner of the first aspect, in a third possible implementation manner of the first aspect, an outgoing line breaker is provided between the low-frequency H bridge and the ac power grid, a first end of the outgoing line breaker is electrically connected with the ac power grid, a second end of the outgoing line breaker is electrically connected with a first end of a first contactor, a second end of the first contactor is electrically connected with a first end of a first inductor, a second end of the first inductor is electrically connected with the low-frequency H bridge, and the first contactor is connected with a first bypass soft start resistor in parallel.
With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, a first dc circuit breaker and a second dc circuit breaker are disposed between the low-voltage dc device and the energy storage end, a first end of the first dc circuit breaker is electrically connected to an anode of the energy storage end, a second end of the first dc circuit breaker is electrically connected to a first end of a second contactor, a second end of the second contactor is electrically connected to a first end of a second inductor, a second end of the second inductor is electrically connected to the first-phase single-H-bridge power module, and the second contactor is connected to a second bypass soft start resistor in parallel; the first end of the second direct current circuit breaker is electrically connected with the negative electrode of the energy storage end, the second end of the second direct current circuit breaker is electrically connected with the first end of the third contactor, the second end of the third contactor is electrically connected with the first end of the third inductor, the second end of the third inductor is electrically connected with the third phase single H bridge power module, and the third contactor is connected with the third bypass soft start resistor in parallel.
With reference to the first aspect or the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner of the first aspect, the energy storage terminal is an energy storage battery pack.
In a second aspect, an embodiment of the present application provides a medium-voltage direct-hanging energy storage converter system, where an operation condition is grid-connected operation start, and the method is used to control the medium-voltage direct-hanging energy storage converter system according to the first aspect or any implementation manner of the first aspect, and the method includes:
selecting a control mode of the high-voltage alternating-current device as a power following control mode, realizing that the active power exchanged between the high-voltage alternating-current device and an alternating-current power grid automatically follows the charging or discharging power of the low-voltage direct-current device through the control, and the reactive power exchanged between the high-voltage alternating-current device and the alternating-current power grid automatically follows the reactive power fixed value issued by the superior dispatching;
selecting a control mode of the low-voltage direct-current device as a constant power control mode, and realizing that the active power exchanged between the low-voltage direct-current device and the energy storage battery automatically follows an active power fixed value issued by a superior dispatching through the control;
closing an outgoing line breaker to charge a first direct current capacitor of the high-voltage alternating current device, then locking a first contactor and a first bypass soft start resistor, unlocking a low-frequency H bridge to control the voltage average value of the first direct current capacitors of all the high-voltage alternating current devices to be a set reference value, and unlocking a first high-frequency H bridge to supply power to a high-frequency bus;
a second high-frequency H bridge of the low-voltage direct-current device is locked, and the high-voltage alternating-current device charges a second direct-current capacitor of the low-voltage direct-current device through a high-frequency bus;
when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the battery pack is smaller than a set value, the low-voltage direct-current device controller closes the direct-current circuit breaker of the port, and the energy storage battery pack is connected to the low-voltage direct-current device;
the low-voltage direct-current device controller unlocks second high-frequency H bridges of all modules of the port, and the low-voltage direct-current device controller is put into operation in a constant-power mode;
and after the low-voltage direct-current device is started, the high-voltage direct-current device sends information to the high-voltage alternating-current device, and the high-voltage alternating-current device is responsible for receiving the fixed values of the active power and the reactive power issued by the upper-level dispatching and coordinating the overall operation of the two ports.
In a third aspect, an embodiment of the present application provides a control method for a medium-voltage direct-hanging energy storage converter system, where an operation condition is a grid-connected operation shutdown, and the method is used to control the medium-voltage direct-hanging energy storage converter system according to the first aspect or any implementation manner of the first aspect, and the method includes:
after the low-voltage direct-current device controller receives a shutdown instruction, immediately and synchronously controlling the power of the high-voltage alternating-current device and the power of the low-voltage direct-current device to be reduced to zero according to a preset slope;
after the power of the high-voltage alternating current device and the low-voltage direct current device is reduced to zero, the high-voltage alternating current device controller coordinates the high-frequency H bridge of the high-voltage alternating current device and the high-frequency H bridge of the low-voltage direct current device to be locked simultaneously, and the high-frequency bus is powered off;
after the high-frequency H bridge of the high-voltage alternating-current device and the high-frequency H bridge of the low-voltage direct-current device are locked, tripping off a direct-current breaker of the low-voltage direct-current device, withdrawing the energy storage battery pack from running, and stopping the low-voltage direct-current device;
and after the low-voltage direct-current device is stopped, the low-frequency H bridge of the high-voltage alternating-current device is locked, the grid-connected switch of the high-voltage alternating-current device is tripped, and the complete machine is stopped.
In a fourth aspect, an embodiment of the present application provides a medium-voltage direct-hanging energy storage converter system, where an operation condition is an off-grid operation start, and the method is used to control the medium-voltage direct-hanging energy storage converter system according to the first aspect or any implementation manner of the first aspect, and the method includes:
selecting a low-frequency H bridge control mode of a high-voltage alternating-current device as a V/F control mode, and selecting a high-frequency H bridge control mode as a direct-current voltage control mode;
selecting the control mode of the low-voltage direct-current device as a following control mode, and realizing that the active power exchanged between the low-voltage direct-current device and the energy storage battery automatically follows the active power output by the high-voltage alternating-current device through the control;
closing a direct current breaker of the low-voltage direct current device, charging a second direct current capacitor of the low-voltage direct current device by the energy storage battery pack through a soft start resistor, and locking a second high-frequency H bridge of the low-voltage direct current device at the stage;
when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the energy storage battery pack is smaller than a set value, the low-voltage direct-current device controller closes the soft start resistance bypass circuit breaker of the port, and the energy storage battery pack is connected to the low-voltage direct-current device;
the low-voltage direct-current device controller unlocks second high-frequency H bridges of all modules of the low-voltage direct-current device, and charges a first direct-current capacitor of the high-voltage alternating-current device module through a high-frequency bus;
after the high-voltage alternating-current device finishes charging, a first high-frequency H bridge of the high-voltage alternating-current device is unlocked, constant voltage control of the first high-frequency H bridge of the high-voltage alternating-current device is started, and closed-loop control is performed on the voltage average value of a first direct-current capacitor of a high-voltage alternating-current device module;
after the voltage average value of the first direct current capacitor of the high-voltage alternating current device is stabilized near a reference value, unlocking a low-frequency H bridge of the high-voltage alternating current device, and putting the high-voltage alternating current device into operation in a low-frequency H bridge V/F control mode;
after the whole energy storage converter is started, the high-voltage alternating current device is responsible for receiving voltage and frequency fixed values issued by a superior dispatching and coordinating the whole operation of the high-voltage alternating current device and the low-voltage direct current device.
In a fifth aspect, an embodiment of the present application provides a medium-voltage direct-hanging energy storage converter system, where an operation condition is an off-grid operation shutdown, and the method is used to control the medium-voltage direct-hanging energy storage converter system according to the first aspect or any implementation manner of the first aspect, and the method includes:
after the high-voltage alternating-current device controller receives a shutdown instruction, an outgoing line breaker of the high-voltage alternating-current device is disconnected, and an external load of the energy storage converter is cut off;
after an outlet circuit breaker of the high-voltage alternating-current device reaches a branch position, a high-voltage alternating-current device controller coordinates synchronous locking of a high-voltage alternating-current device and a high-frequency H bridge of the low-voltage direct-current device, and a high-frequency bus loses power;
after the high-frequency H bridge of the high-voltage alternating-current device and the high-frequency H bridge of the low-voltage direct-current device are locked, a direct-current circuit breaker of the low-voltage direct-current device is disconnected, the energy storage battery pack quits running, and the low-voltage direct-current device finishes stopping;
and after the low-voltage direct-current device is stopped, the low-frequency H bridge of the high-voltage alternating-current device is locked, and the whole energy storage converter is stopped.
Drawings
Fig. 1 is a schematic structural diagram of a medium-voltage direct-hanging energy storage converter system according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a dual H-bridge power module according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a single H-bridge power module according to an embodiment of the present disclosure;
fig. 4 is a schematic flow chart of a control method of a medium-voltage direct-hanging energy storage converter system according to an embodiment of the present application;
fig. 5 is a schematic flow chart of a control method for a medium-voltage direct-hanging energy storage converter system according to an embodiment of the present application;
fig. 6 is a schematic flow chart of a control method for a medium-voltage direct-hanging energy storage converter system according to an embodiment of the present application;
fig. 7 is a schematic flowchart of a control method for a medium-voltage direct-hanging energy storage converter system according to an embodiment of the present application;
in fig. 1 to 7, the symbols are represented as:
h1-a low-frequency H bridge, H2-a first high-frequency H bridge, H3-a second high-frequency H bridge, C1-a first direct-current capacitor, C2-a second direct-current capacitor, T1-a first high-frequency transformer, T2-a second high-frequency transformer, QS 11-an outgoing line breaker, QS 12-a first contactor, QS 21-a first direct-current breaker, QS 22-a second direct-current breaker, QS 23-a second contactor, QS 24-a third contactor, R1-a first bypass soft start resistor, R2-a second bypass soft start resistor, R3-a third bypass soft start resistor, L1-a first inductor, L2-a second inductor and L3-a third inductor.
Detailed Description
The present invention will be described with reference to the accompanying drawings and embodiments.
The first embodiment is as follows:
fig. 1 is a schematic structural diagram of a medium-voltage straightly-hanging energy storage converter system provided in an embodiment of the present application, and referring to fig. 1, the medium-voltage straightly-hanging energy storage converter system in the embodiment includes: the high-voltage alternating current device is electrically connected with an alternating current power grid, the low-voltage direct current device is electrically connected with an energy storage end, the high-voltage alternating current device is electrically connected with the low-voltage direct current device through a high-frequency transformer, and the energy storage end is an energy storage battery pack. In the embodiment, the high-voltage alternating-current device is in a three-phase star connection mode, each phase is formed by connecting double H-bridge power modules in series, and the low-voltage direct-current device is formed by connecting single H-bridge power modules in parallel.
Referring to fig. 2, the dual H-bridge power module includes a low-frequency H-bridge H1, a first dc capacitor C1, and a first high-frequency H-bridge H2, the low-frequency H-bridge H1, the first dc capacitor C1, and the first high-frequency H-bridge H2 are connected in parallel, an input terminal of the low-frequency H-bridge H1 is electrically connected to an ac power grid, an output terminal of the first high-frequency H-bridge H2 is electrically connected to an input terminal of a first high-frequency transformer T1, and an output terminal of the first high-frequency transformer T1 is electrically connected to the single H-bridge power module.
Referring to fig. 3, the single H-bridge power module includes a second high-frequency H-bridge H3 and a second dc capacitor C2, the second high-frequency H-bridge H3 and the second dc capacitor C2 are connected in parallel, an input terminal of the second high-frequency H-bridge H3 is electrically connected to an output terminal of a second high-frequency transformer T2, and an input terminal of the second high-frequency transformer T2 is electrically connected to an output terminal of the first high-frequency transformer T1.
Further referring to fig. 1, an outgoing line breaker QS11 is arranged between the low-frequency H bridge H1 and an ac power grid, a first end of the outgoing line breaker QS11 is electrically connected to the ac power grid, a second end of the outgoing line breaker QS11 is electrically connected to a first end of a first contactor QS12, a second end of the first contactor QS12 is electrically connected to a first end of a first inductor L1, a second end of the first inductor L1 is electrically connected to the low-frequency H bridge H1, and the first contactor QS12 is connected to a first bypass soft start resistor R1 in parallel.
Be provided with first direct current circuit breaker QS21 and second direct current circuit breaker QS22 between low-voltage direct current device and the energy storage end, first direct current circuit breaker QS 21's first end and energy storage end positive pole electricity are connected, first direct current circuit breaker QS 21's second end is connected with the first end electricity of second contactor QS23, second contactor QS 23's second end is connected with the first end electricity of second inductance L2, the second end and the first single H bridge power module electricity of looks of second inductance L2 are connected, second bypass soft start resistance R2 is connected in parallel to second contactor QS 23.
The first end of the second direct current breaker QS22 is electrically connected with the negative electrode of the energy storage end, the second end of the second direct current breaker QS22 is electrically connected with the first end of a third contactor QS24, the second end of the third contactor QS24 is electrically connected with the first end of a third inductor L3, the second end of the third inductor L3 is electrically connected with a third phase single H bridge power module, and the third contactor QS24 is connected with a third bypass soft start resistor R3 in parallel.
Corresponding to the medium-voltage straightly-hanging energy storage and conversion system provided by the embodiment, the application also provides an embodiment for controlling the start and stop of the medium-voltage straightly-hanging energy storage and conversion system.
Example two:
the embodiment provides a control method for a medium-voltage direct-hanging energy storage converter system, and particularly provides a grid-connected operation starting control method for the medium-voltage direct-hanging energy storage converter system. Referring to fig. 4, the method includes:
s101, selecting a control mode of the high-voltage alternating-current device as a power following control mode, realizing that the active power exchanged between the high-voltage alternating-current device and the alternating-current power grid automatically follows the charging or discharging power of the low-voltage direct-current device through the control, and the reactive power exchanged between the high-voltage alternating-current device and the alternating-current power grid automatically follows the reactive power fixed value issued by the superior scheduling.
And S102, selecting the control mode of the low-voltage direct-current device as a constant power control mode, and realizing that the active power exchanged between the low-voltage direct-current device and the energy storage battery automatically follows the active power fixed value issued by the upper-level scheduling through the control.
S103, the outgoing line breaker is closed to charge the first direct current capacitors of the high-voltage alternating current devices, then the first contactor and the first bypass soft start resistor are locked, the low-frequency H bridge is unlocked to control the average voltage value of the first direct current capacitors of all the high-voltage alternating current devices to be a set reference value, and the first high-frequency H bridge is unlocked to supply power to the high-frequency bus.
And S104, locking a second high-frequency H bridge of the low-voltage direct-current device, and charging a second direct-current capacitor of the low-voltage direct-current device by the high-voltage alternating-current device through a high-frequency bus.
And S105, when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the battery pack is smaller than a set value, closing the direct-current breaker of the port by the low-voltage direct-current device controller, and connecting the energy storage battery pack to the low-voltage direct-current device.
And S106, unlocking second high-frequency H bridges of all modules of the port by the low-voltage direct-current device controller, and putting the modules into operation in a constant-power mode.
And S107, after the low-voltage direct-current device is started, sending information to the high-voltage alternating-current device, and the high-voltage alternating-current device is responsible for receiving the active power and reactive power fixed values sent by the upper-level dispatching and coordinating the overall operation of the two ports.
Example three:
the embodiment provides a control method of a medium-voltage direct-hanging energy storage converter system, and particularly provides a grid-connected operation shutdown control method of the medium-voltage direct-hanging energy storage converter system. Referring to fig. 5, the method includes:
s201, after the low-voltage direct current device controller receives a stop instruction, the power of the high-voltage alternating current device and the power of the low-voltage direct current device are immediately and synchronously controlled to be reduced to zero according to a preset slope.
And S202, after the power of the high-voltage alternating current device and the low-voltage direct current device is reduced to zero, the high-voltage alternating current device controller coordinates the high-frequency H bridge of the high-voltage alternating current device and the high-frequency H bridge of the low-voltage direct current device to be locked simultaneously, and the high-frequency bus is powered off.
And S203, after the high-voltage alternating current device and the high-frequency H bridge of the low-voltage direct current device are locked, tripping off the direct current breaker of the low-voltage direct current device, withdrawing the energy storage battery pack from operation, and stopping the low-voltage direct current device.
And S204, after the low-voltage direct-current device is stopped, locking the low-frequency H bridge of the high-voltage alternating-current device, tripping the grid-connected switch of the high-voltage alternating-current device, and stopping the operation of the whole machine.
Example four:
the embodiment provides a control method for a medium-voltage direct-hanging energy storage converter system, and particularly provides an off-network operation starting control method for the medium-voltage direct-hanging energy storage converter system. Referring to fig. 6, the method includes:
s301, selecting a low-frequency H bridge control mode of the high-voltage alternating-current device as a V/F control mode, and selecting a high-frequency H bridge control mode as a direct-current voltage control mode.
And S302, selecting the control mode of the low-voltage direct current device as a following control mode, and realizing that the active power exchanged between the low-voltage direct current device and the energy storage battery automatically follows the active power output by the high-voltage alternating current device through the control.
And S303, closing the direct current breaker of the low-voltage direct current device, charging a second direct current capacitor of the low-voltage direct current device by the energy storage battery pack through a soft start resistor, and locking a second high-frequency H bridge of the low-voltage direct current device at the stage.
And S304, when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the energy storage battery pack is smaller than a set value, the low-voltage direct-current device controller closes the soft start resistor bypass circuit breaker at the port, and the energy storage battery pack is connected to the low-voltage direct-current device.
And S305, unlocking second high-frequency H bridges of all modules of the low-voltage direct-current device by the low-voltage direct-current device controller, and charging first direct-current capacitors of the high-voltage alternating-current device modules through high-frequency buses.
And S306, after the high-voltage alternating-current device finishes charging, unlocking a first high-frequency H bridge of the high-voltage alternating-current device, starting constant voltage control of the first high-frequency H bridge of the high-voltage alternating-current device, and performing closed-loop control on the voltage average value of a first direct-current capacitor of a high-voltage alternating-current device module.
And S307, after the voltage average value of the first direct current capacitor of the high-voltage alternating current device is stabilized near the reference value, unlocking the low-frequency H bridge of the high-voltage alternating current device, and putting the high-voltage alternating current device into operation in a low-frequency H bridge V/F control mode.
And S308, after the whole energy storage converter is started, the high-voltage alternating current device is responsible for receiving the voltage and frequency fixed values issued by the upper-level dispatching and coordinating the whole operation of the high-voltage alternating current device and the low-voltage direct current device.
Example five:
the embodiment provides a control method of a medium-voltage direct-hanging energy storage converter system, and particularly provides an off-network operation shutdown control method of the medium-voltage direct-hanging energy storage converter system. Referring to fig. 7, the method includes:
and S401, after the high-voltage alternating-current device controller receives a shutdown instruction, disconnecting an outgoing line breaker of the high-voltage alternating-current device and cutting off an external load of the energy storage converter.
S402, after the outgoing line breaker of the high-voltage alternating-current device reaches the branch position, the high-voltage alternating-current device controller coordinates synchronous locking of the high-voltage alternating-current device and the high-frequency H bridge of the low-voltage direct-current device, and the high-frequency bus is in power loss.
And S403, after the high-voltage alternating current device and the high-frequency H bridge of the low-voltage direct current device are locked, disconnecting the direct current breaker of the low-voltage direct current device, withdrawing the energy storage battery pack from operation, and stopping the low-voltage direct current device.
And S404, after the low-voltage direct-current device is stopped, locking the low-frequency H bridge of the high-voltage alternating-current device, and stopping the whole energy storage converter.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (10)
1. A medium-voltage direct-hanging energy storage converter system is characterized by comprising: the high-voltage alternating current device is electrically connected with an alternating current power grid, and the low-voltage direct current device is electrically connected with an energy storage end; the high-voltage alternating-current device is in a three-phase star connection mode, each phase is formed by connecting double H-bridge power modules in series, and the low-voltage direct-current device is formed by connecting single H-bridge power modules in parallel.
2. The medium voltage direct-hanging energy storage and conversion system according to claim 1, wherein the double H-bridge power module comprises a low-frequency H-bridge, a first dc capacitor and a first high-frequency H-bridge, the low-frequency H-bridge, the first dc capacitor and the first high-frequency H-bridge are connected in parallel, an input end of the low-frequency H-bridge is electrically connected to an ac power grid, an output end of the first high-frequency H-bridge is electrically connected to an input end of a first high-frequency transformer, and an output end of the first high-frequency transformer is electrically connected to the single H-bridge power module.
3. The medium voltage direct hanging energy storage and conversion system according to claim 2, wherein the single H-bridge power module comprises a second high frequency H-bridge and a second dc capacitor, the second high frequency H-bridge and the second dc capacitor are connected in parallel, an input terminal of the second high frequency H-bridge is electrically connected to an output terminal of a second high frequency transformer, and an input terminal of the second high frequency transformer is electrically connected to an output terminal of the first high frequency transformer.
4. The medium voltage direct hanging energy storage and conversion system according to any one of claims 1-3, wherein an outgoing line breaker is disposed between the low frequency H bridge and an AC power grid, a first end of the outgoing line breaker is electrically connected to the AC power grid, a second end of the outgoing line breaker is electrically connected to a first end of a first contactor, a second end of the first contactor is electrically connected to a first end of a first inductor, a second end of the first inductor is electrically connected to the low frequency H bridge, and the first contactor is connected in parallel to a first bypass soft start resistor.
5. The medium-voltage direct-hanging energy storage and conversion system according to claim 4, wherein a first direct-current circuit breaker and a second direct-current circuit breaker are arranged between the low-voltage direct-current device and the energy storage end, a first end of the first direct-current circuit breaker is electrically connected with an anode of the energy storage end, a second end of the first direct-current circuit breaker is electrically connected with a first end of a second contactor, a second end of the second contactor is electrically connected with a first end of a second inductor, a second end of the second inductor is electrically connected with the first-phase single H-bridge power module, and the second contactor is connected with a second bypass soft start resistor in parallel;
the first end of the second direct current circuit breaker is electrically connected with the negative electrode of the energy storage end, the second end of the second direct current circuit breaker is electrically connected with the first end of the third contactor, the second end of the third contactor is electrically connected with the first end of the third inductor, the second end of the third inductor is electrically connected with the third phase single H bridge power module, and the third contactor is connected with the third bypass soft start resistor in parallel.
6. The medium voltage direct hanging energy storage and conversion system according to claim 1 or 5, wherein the energy storage terminal is an energy storage battery pack.
7. A method for controlling a medium-voltage hanging energy-storage converter system, wherein the operation condition is grid-connected operation starting, and the method is used for controlling the medium-voltage hanging energy-storage converter system as claimed in any one of claims 1 to 6, and the method comprises the following steps:
selecting a control mode of the high-voltage alternating-current device as a power following control mode, realizing that the active power exchanged between the high-voltage alternating-current device and an alternating-current power grid automatically follows the charging or discharging power of the low-voltage direct-current device through the control, and the reactive power exchanged between the high-voltage alternating-current device and the alternating-current power grid automatically follows the reactive power fixed value issued by the superior dispatching;
selecting a control mode of the low-voltage direct-current device as a constant power control mode, and realizing that the active power exchanged between the low-voltage direct-current device and the energy storage battery automatically follows an active power fixed value issued by a superior dispatching through the control;
closing an outgoing line breaker to charge a first direct current capacitor of the high-voltage alternating current device, then locking a first contactor and a first bypass soft start resistor, unlocking a low-frequency H bridge to control the voltage average value of the first direct current capacitors of all the high-voltage alternating current devices to be a set reference value, and unlocking a first high-frequency H bridge to supply power to a high-frequency bus;
a second high-frequency H bridge of the low-voltage direct-current device is locked, and the high-voltage alternating-current device charges a second direct-current capacitor of the low-voltage direct-current device through a high-frequency bus;
when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the battery pack is smaller than a set value, the low-voltage direct-current device controller closes the direct-current circuit breaker of the port, and the energy storage battery pack is connected to the low-voltage direct-current device;
the low-voltage direct-current device controller unlocks second high-frequency H bridges of all modules of the port, and the low-voltage direct-current device controller is put into operation in a constant-power mode;
and after the low-voltage direct-current device is started, the high-voltage direct-current device sends information to the high-voltage alternating-current device, and the high-voltage alternating-current device is responsible for receiving the fixed values of the active power and the reactive power issued by the upper-level dispatching and coordinating the overall operation of the two ports.
8. A control method for a medium-voltage direct-hanging energy-storage converter system, the operation condition is grid-connected operation shutdown, and the method is used for controlling the medium-voltage direct-hanging energy-storage converter system of any one of claims 1 to 6, and the method comprises the following steps:
after the low-voltage direct-current device controller receives a shutdown instruction, immediately and synchronously controlling the power of the high-voltage alternating-current device and the power of the low-voltage direct-current device to be reduced to zero according to a preset slope;
after the power of the high-voltage alternating current device and the low-voltage direct current device is reduced to zero, the high-voltage alternating current device controller coordinates the high-frequency H bridge of the high-voltage alternating current device and the high-frequency H bridge of the low-voltage direct current device to be locked simultaneously, and the high-frequency bus is powered off;
after the high-frequency H bridge of the high-voltage alternating-current device and the high-frequency H bridge of the low-voltage direct-current device are locked, tripping off a direct-current breaker of the low-voltage direct-current device, withdrawing the energy storage battery pack from running, and stopping the low-voltage direct-current device;
and after the low-voltage direct-current device is stopped, the low-frequency H bridge of the high-voltage alternating-current device is locked, the grid-connected switch of the high-voltage alternating-current device is tripped, and the complete machine is stopped.
9. A method for controlling a medium-voltage hanging type energy storage converter system, wherein the operation condition is off-grid operation starting, and the method is used for controlling the medium-voltage hanging type energy storage converter system as claimed in any one of claims 1 to 6, and the method comprises the following steps:
selecting a low-frequency H bridge control mode of a high-voltage alternating-current device as a V/F control mode, and selecting a high-frequency H bridge control mode as a direct-current voltage control mode;
selecting the control mode of the low-voltage direct-current device as a following control mode, and realizing that the active power exchanged between the low-voltage direct-current device and the energy storage battery automatically follows the active power output by the high-voltage alternating-current device through the control;
closing a direct current breaker of the low-voltage direct current device, charging a second direct current capacitor of the low-voltage direct current device by the energy storage battery pack through a soft start resistor, and locking a second high-frequency H bridge of the low-voltage direct current device at the stage;
when the deviation between the capacitor voltage of the low-voltage direct-current device and the total voltage of the energy storage battery pack is smaller than a set value, the low-voltage direct-current device controller closes the soft start resistance bypass circuit breaker of the port, and the energy storage battery pack is connected to the low-voltage direct-current device;
the low-voltage direct-current device controller unlocks second high-frequency H bridges of all modules of the low-voltage direct-current device, and charges a first direct-current capacitor of the high-voltage alternating-current device module through a high-frequency bus;
after the high-voltage alternating-current device finishes charging, a first high-frequency H bridge of the high-voltage alternating-current device is unlocked, constant voltage control of the first high-frequency H bridge of the high-voltage alternating-current device is started, and closed-loop control is performed on the voltage average value of a first direct-current capacitor of a high-voltage alternating-current device module;
after the voltage average value of the first direct current capacitor of the high-voltage alternating current device is stabilized near a reference value, unlocking a low-frequency H bridge of the high-voltage alternating current device, and putting the high-voltage alternating current device into operation in a low-frequency H bridge V/F control mode;
after the whole energy storage converter is started, the high-voltage alternating current device is responsible for receiving voltage and frequency fixed values issued by a superior dispatching and coordinating the whole operation of the high-voltage alternating current device and the low-voltage direct current device.
10. A method for controlling a medium-voltage hanging type energy storage converter system, wherein the operation condition is off-grid operation shutdown, and the method is used for controlling the medium-voltage hanging type energy storage converter system as claimed in any one of claims 1 to 6, and the method comprises the following steps:
after the high-voltage alternating-current device controller receives a shutdown instruction, an outgoing line breaker of the high-voltage alternating-current device is disconnected, and an external load of the energy storage converter is cut off;
after an outlet circuit breaker of the high-voltage alternating-current device reaches a branch position, a high-voltage alternating-current device controller coordinates synchronous locking of a high-voltage alternating-current device and a high-frequency H bridge of the low-voltage direct-current device, and a high-frequency bus loses power;
after the high-frequency H bridge of the high-voltage alternating-current device and the high-frequency H bridge of the low-voltage direct-current device are locked, a direct-current circuit breaker of the low-voltage direct-current device is disconnected, the energy storage battery pack quits running, and the low-voltage direct-current device finishes stopping;
and after the low-voltage direct-current device is stopped, the low-frequency H bridge of the high-voltage alternating-current device is locked, and the whole energy storage converter is stopped.
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