CN116565927B - Battery energy storage system with fault tolerance function - Google Patents

Battery energy storage system with fault tolerance function Download PDF

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Publication number
CN116565927B
CN116565927B CN202310851365.4A CN202310851365A CN116565927B CN 116565927 B CN116565927 B CN 116565927B CN 202310851365 A CN202310851365 A CN 202310851365A CN 116565927 B CN116565927 B CN 116565927B
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phase
unit
fault
isolation
bypass
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CN116565927A (en
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张文平
王一鸣
许颇
季建强
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Ginlong Technologies Co Ltd
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Ginlong Technologies Co Ltd
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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
    • 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
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/10—Flexible AC transmission systems [FACTS]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The application discloses a battery energy storage system with a fault tolerance function, which comprises a traditional battery energy storage system and an isolation module; when one phase of the three-phase DC/AC unit fails, the isolation module is suitable for disconnecting the output of the failed phase of the three-phase DC/AC unit, so that the three-phase DC/AC unit performs two-phase operation of fault isolation; when the DC/DC unit fails, the isolation module is suitable for disconnecting the output of one phase of the three-phase DC/AC unit as an isolated phase so that the three-phase DC/AC unit performs two-phase operation; the isolation phase is adapted to be directly connected to the battery via the isolation module, thereby isolating the faulty DC/DC unit. The application has the beneficial effects that: compared with the traditional parallel fault-tolerant mode, the application realizes different types of fault isolation of different devices only by the isolation module, and has simple implementation mode and low cost.

Description

Battery energy storage system with fault tolerance function
Technical Field
The application relates to the technical field of new energy power generation, in particular to a battery energy storage system with a fault tolerance function.
Background
The energy storage system has the time migration capability for power and energy, and can effectively inhibit challenges of wind and light power source power fluctuation on grid frequency modulation and load tracking, so that the reliability of the energy storage system is very important.
The energy storage system is used with a power electronic converter, and the power electronic device is considered as a relatively weak link in the power electronic converter. When the power electronic device breaks down, if the system is not isolated timely, the fault can be diffused, so that the whole system is crashed. Therefore, achieving system fault tolerance is a very important method to improve system reliability. However, most of the existing fault tolerant circuits are direct parallel connection of the systems, and are high in reliability and high in cost. Therefore, how to design a fault tolerant system with high reliability and low cost is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
One of the objects of the present application is to provide a battery energy storage system with fault tolerance that can be implemented in a simple manner at a reduced cost.
In order to achieve the purpose, the application adopts the following technical scheme: the battery energy storage system with the fault tolerance function comprises a battery, a DC/DC unit and a three-phase DC/AC unit which are sequentially connected, and further comprises an isolation module, wherein the three-phase DC/AC unit is suitable for being connected with the battery and a power grid respectively through the isolation module; when a certain phase of the three-phase DC/AC unit fails, the isolation module is suitable for disconnecting the failed phase output of the three-phase DC/AC unit, so that the three-phase DC/AC unit performs two-phase operation of fault isolation; when the DC/DC unit fails, the isolation module is suitable for disconnecting one phase output of the three-phase DC/AC unit to serve as an isolation phase, so that the three-phase DC/AC unit performs two-phase operation; the isolation phase is suitable for being directly connected with the battery through the isolation module, so that the fault DC/DC unit is isolated.
Preferably, the isolation module comprises a switch unit and a first bypass unit; each phase output of the three-phase DC/AC unit is connected with the power grid through the switch unit; the positive end of the battery is connected with a bridge arm of the three-phase DC/AC unit through the first bypass unit which is normally open; when an open circuit fault occurs to one phase of the three-phase DC/AC unit, the switch unit is suitable for disconnecting the fault phase of the three-phase DC/AC unit from the power grid, so that the three-phase DC/AC unit performs two-phase operation; when the DC/DC unit has an open-circuit fault, the switch unit is suitable for disconnecting the isolation phase from the power grid, and then the positive end of the battery is directly connected with the isolation phase through the closed conduction of the first bypass unit.
Preferably, when an open circuit fault occurs in a certain phase of the three-phase DC/AC unit, the three-phase DC/AC unit is adapted to perform drive blocking first, and the switching unit disconnects the fault phase of the three-phase DC/AC unit from the power grid; after the switching unit is completely disconnected, the three-phase DC/AC unit is suitable for restarting the non-fault phase to perform two-phase operation; when the DC/DC unit has an open-circuit fault, the three-phase DC/AC unit and the DC/DC unit are suitable for driving and blocking, and meanwhile, the isolation phase of the three-phase DC/AC unit is disconnected from the power grid through the switch unit; after the switching unit is completely disconnected, the non-isolated phase of the three-phase DC/AC unit is suitable for restarting, and the first bypass unit is conducted at the same time.
Preferably, the isolation module further includes a pair of second bypass units and a plurality of fuses; the positive end and the negative end of the three-phase DC/AC unit are connected with the power grid through the second bypass unit; each phase output of the three-phase DC/AC unit and the input of the DC/DC unit are connected with the fuse; when a short-circuit fault occurs in one phase of the three-phase DC/AC unit, the fault phase of the three-phase DC/AC unit forms a fusing loop through the second bypass unit, and then the fuse corresponding to the output of the fault phase is fused; when the DC/DC unit has a short-circuit fault, the DC/DC unit is suitable for forming a fusing loop through the second bypass unit, so that the corresponding fuse is fused through the input of the DC/DC unit, and meanwhile, the isolation phase is disconnected with the power grid through the switch unit.
Preferably, when a short-circuit fault occurs in a certain phase of the three-phase DC/AC unit, the three-phase DC/AC unit is first driven and blocked, and the switching unit corresponding to the non-fault is disconnected; fusing the fuse corresponding to the fault, and restarting the non-fault phase of the three-phase DC/AC unit after fusing; when the DC/DC unit has short-circuit fault, the DC/DC unit and the three-phase DC/AC unit are firstly driven and blocked, and the switch unit is completely disconnected; and then fusing the fuse corresponding to the DC/DC unit, closing and conducting the first bypass unit after fusing, and closing the switch unit corresponding to the non-isolation of the three-phase DC/AC unit.
Preferably, the given currents of the three-phase DC/AC unit in two-phase operation are respectively i 1 * And i 2 * And setting the active power loop output of the three-phase DC/AC unit as I d * The reactive power loop output is I q * The method comprises the steps of carrying out a first treatment on the surface of the Then:
；
；
where ωt represents the product of the angular frequency ω and time t, i.e. the phase.
Preferably, the first bypass unit comprises a thyristor, and the positive terminal of the battery is adapted to be connected to any phase leg of the three-phase DC/AC unit via the thyristor.
Preferably, the first bypass unit comprises three thyristors, and the positive end of the battery is suitable for being correspondingly connected with the three-phase bridge arm of the three-phase DC/AC unit through the thyristors respectively.
Preferably, the second bypass unit is in a normally open state, the second bypass unit comprises a thyristor, and the positive and negative ends of the three-phase DC/AC unit are respectively connected with the power grid through corresponding thyristors.
Preferably, the second bypass unit further includes a current limiting resistor connected in series with the thyristor.
Compared with the prior art, the application has the beneficial effects that:
compared with the single fault tolerance method of the traditional energy storage system, the fault tolerance method of the three-phase DC/AC unit can process different fault types of the DC/DC unit and the three-phase DC/AC unit, and further the fault tolerance degree of the battery energy storage system can be effectively improved. Compared with the traditional parallel fault-tolerant mode, the fault isolation method and the fault isolation device only need to realize different types of fault isolation of different devices through the isolation module, and are simple in implementation mode and low in cost.
Drawings
Fig. 1 is a schematic circuit diagram of a conventional battery energy storage system.
Fig. 2 is a schematic circuit diagram of a battery energy storage system according to a first embodiment of the application.
FIG. 3 shows a device S of a DC/AC unit in the embodiment of FIG. 2 of the present application a1 Schematic of a fuse circuit when a short circuit fault occurs.
FIG. 4 shows a device S of a DC/AC unit in the embodiment of FIG. 2 according to the present application a1 And carrying out fault isolation on a system operation circuit structure schematic diagram.
FIG. 5 shows a device S of a DC/AC unit in the embodiment of FIG. 2 according to the present application a1 And carrying out system current vector diagrams before and after fault isolation.
FIG. 6 shows a device S of the DC/DC unit in the embodiment of FIG. 2 according to the present application DC1 Schematic of a fuse circuit when a short circuit fault occurs.
FIG. 7 shows a device S of a DC/AC unit in the embodiment of FIG. 2 according to the present application DC1 And carrying out fault isolation on a system operation circuit structure schematic diagram.
Fig. 8 is a schematic circuit diagram of a battery energy storage system according to a second embodiment of the application.
Fig. 9 is a schematic circuit diagram of a battery energy storage system according to a third embodiment of the present application.
Fig. 10 is a schematic circuit diagram of a battery energy storage system according to a fourth embodiment of the present application.
In the figure: a battery 110, a DC/DC unit 120, a three-phase DC/AC unit 130, a switching unit 140, a power grid 150, a first bypass unit 210, a second bypass unit 220.
Detailed Description
The present application will be further described with reference to the following specific embodiments, and it should be noted that, on the premise of no conflict, new embodiments may be formed by any combination of the embodiments or technical features described below.
In the description of the present application, it should be noted that, for the azimuth words such as terms "center", "lateral", "longitudinal", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., the azimuth and positional relationships are based on the azimuth or positional relationships shown in the drawings, it is merely for convenience of describing the present application and simplifying the description, and it is not to be construed as limiting the specific scope of protection of the present application that the device or element referred to must have a specific azimuth configuration and operation.
It should be noted that the terms "first," "second," and the like in the description and in the claims are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order.
Fig. 1 is a schematic circuit diagram of a conventional battery energy storage system; the existing battery energy storage system mainly comprises a battery 110, a DC/DC unit 120 and a three-phase DC/AC unit 130 which are connected in sequence; the outputs of the three-phase DC/AC unit 130 are connected to a power grid 150. The specific principles and processes of operation of battery energy storage systems are well known to those skilled in the art and will not be described in detail herein. In the whole battery energy storage system, the DC/DC unit 120 and the three-phase DC/AC unit 130 are the most important two devices and are also the two devices which are easier to break down; thus, fault tolerant settings for the battery energy storage system are primarily directed to faults of the DC/DC unit 120 and the three-phase DC/AC unit 130; and, the three-phase DC/AC unit 130 can continue to operate after fault isolation only when a certain phase thereof fails, and the three-phase DC/AC unit 130 cannot operate due to the failure of the multiple phases. Accordingly, the fault isolation of the battery energy storage system is based on the premise that one of the phases of the DC/DC unit 120 and the three-phase DC/AC unit 130 is faulty.
Based on the foregoing, one of the preferred embodiments of the present application, as shown in fig. 2 to 10, is a battery energy storage system with fault tolerance function, and further includes an isolation module based on the existing battery energy storage system. The three-phase DC/AC unit 130 may be connected to the battery 110 and the power grid 150, respectively, through an isolation module. When a certain phase of the three-phase DC/AC unit 130 fails, the isolation module may disconnect the output of the failed phase of the three-phase DC/AC unit 130, thereby isolating the failed phase of the three-phase DC/AC unit 130, and then the three-phase DC/AC unit 130 may perform a two-phase operation with fault isolation. When the DC/DC unit 120 fails, the isolation module may control the output of one phase of the three-phase DC/AC unit 130 to be disconnected, so that the three-phase DC/AC unit 130 performs two-phase operation, and directly connects the disconnected output phase of the three-phase DC/AC unit 130 with the battery 110, so as to isolate the failed DC/DC unit 120 from the battery energy storage system.
It will be appreciated that the type of fault is different (short circuit and open circuit) depending on the device that is faulty (one phase of the DC/DC unit 120 and the three-phase DC/AC unit 130); the isolation modules may form different isolation circuits and implement fault tolerant isolation in conjunction with two-phase operation of the three-phase DC/AC unit 130 to achieve different failure modes. Compared with the traditional parallel fault-tolerant mode, the application can effectively reduce the design difficulty and cost, and the implementation mode of fault-tolerant isolation of faults is simpler.
It should be appreciated by those skilled in the art that the types of faults of the DC/DC unit 120 and the three-phase DC/AC unit 130 include open-circuit faults and short-circuit faults. Specific operation modes of the isolation module are different for different fault types, and detailed description can be made for different fault types for convenience of understanding.
As shown in fig. 2 to 10, the isolation module includes a switching unit 140, a first bypass unit 210, a pair of second bypass units 220, and a plurality of fuses. The phase outputs of the three-phase DC/AC unit 130 are connected to the grid 150 through the switching unit 140; the positive terminal of the battery 110 is connected with the bridge arm of the three-phase DC/AC unit 130 through the first bypass unit 210; the positive and negative terminals of the three-phase DC/AC unit 130 are connected to the power grid 150 through the second bypass unit 220; the outputs of each phase of the three-phase DC/AC unit 130 and the inputs of the DC/DC unit 120 are all connected with fuses. When the battery energy storage system of the present application is in a normal operation state, the first bypass unit 210 and the second bypass unit 220 are both in an open state, and the switch unit 140 is in a closed state.
1. A short circuit fault occurs for a certain phase of the three-phase DC/AC unit 130.
As shown in fig. 3 and 4, when a short-circuit fault occurs in a certain phase of the three-phase DC/AC unit 130, the three-phase DC/AC unit 130 may be first drive blocked, and the non-fault-corresponding switching unit 140 of the three-phase DC/AC unit 130 may be opened, so that the connection between the non-fault phase of the three-phase DC/AC unit 130 and the power grid 150 is disconnected. At this time, the second bypass unit 220 may be turned on, so that the fault phase of the three-phase DC/AC unit 130 may form a fusing circuit through the second bypass unit 220, and further, a fuse corresponding to the fault phase output of the three-phase DC/AC unit 130 may be fused through the fusing circuit. The restarting may be achieved by releasing the driving lockout of the non-fault phase of the three-phase DC/AC unit 130 after the fuse breaking is completed, so that the three-phase DC/AC unit 130 performs the two-phase operation to continue the normal operation of the battery energy storage system.
It will be appreciated that during fault isolation of the three-phase DC/AC unit 130, since the DC/DC unit 120 is in a normal state, the DC/DC unit 120 does not need to be driven off, and the first bypass unit 210 may be kept off to avoid interference of the first bypass unit 210 with normal operation of the DC/DC unit 120.
For further understanding, the following description will be made by referring to a specific embodiment, and since the A, B and C three phases of the three-phase DC/AC unit 130 are processed in the same manner in fault isolation, the a phase of the three-phase DC/AC unit 130 is failed.
Specifically, as shown in fig. 3 and 4, the three-phase DC/AC unit 130 includes an a-phase bridge arm, a B-phase bridge arm, and a C-phase bridge arm; the A-phase bridge arm comprises a device S a1 And S is a2 The B-phase bridge arm comprises a device S b1 And S is b2 The C-phase bridge arm comprises a device S c1 And S is c2 . The switching unit 140 includes contactors T respectively and correspondingly connected to the three phases of the three-phase DC/AC unit 130 a 、T b And T c . The three-phase outputs of the three-phase DC/AC unit 130 are respectively and correspondingly connected with fuses F a 、F b And F c 。
Assume device S of three-phase DC/AC unit 130 a1 Short-circuit fault occurs in the device S a1 After the failure detection is successful, all the devices of the three-phase DC/AC unit 130 may be connected (S a1 ~S c2 ) To perform driving blocking and simultaneously to connect the contactor T b And T c Disconnecting; and then can be connected with the device S a2 The corresponding second bypass unit 220 conducts to short-circuited device S a1 Fuse F a Contactor T a Grid 150, second bypass unit 220 and capacitor C dc Are communicated with each other to form a fusing loop (thickened line shown in figure 3) which is further connected with a capacitor C dc Supplying power to the fusing circuit to cause the fuse F a Is fused. Fuse F to be fused a After the fusing, the corresponding second bypass unit 220 may be disconnected again; then, the non-fault phases B and C of the three-phase DC/AC unit 130 are restarted, so that the three-phase DC/AC unit 130 operates in the two-phase operation mode.
In this embodiment, as shown in fig. 2 to 4 and fig. 6 to 10, the second bypass unit 220 includes a thyristor, and the thyristor is in a normally open state, that is, when the battery energy storage system works normally, the second bypass unit 220 maintains an off state through the normally open state of the thyristor; when fault isolation is performed, the second bypass unit 220 remains conductive through the closing of the thyristor. Since there are two second bypass units 220, for better discrimination, the thyristors included in the second bypass unit 220 connected to the positive side of the three-phase DC/AC unit 130 may be labeled T AC1 The thyristor comprised by the second bypass unit 220 connected to the negative terminal of the three-phase DC/AC unit 130 is denoted T AC2 . Then device S near the positive side in three-phase DC/AC unit 130 a1 、S b1 And S is c1 When a fault occurs, the thyristor T AC1 Will remain open while the thyristor T AC2 Closing is carried out; similarly, device S in three-phase DC/AC unit 130 near the negative terminal a2 、S b2 And S is c2 Failure occursAt the time, thyristor T AC2 Will remain open while the thyristor T AC1 Closing will take place.
In this embodiment, as shown in fig. 2 to 4 and fig. 6 to 10, the second bypass unit 220 further includes a current limiting resistor, and the current limiting resistor can be connected in series with a corresponding thyristor, so that when the second bypass unit 220 forms a fusing circuit, the current limiting resistor can limit the short-circuit current, thereby improving the safety of the fusing circuit. In particular, with thyristor T AC1 The series current limiting resistor is R AC1 And thyristor T AC2 The series current limiting resistor is R AC2 。
2. An open circuit fault occurs for a certain phase of the three-phase DC/AC unit 130.
When an open circuit fault occurs in a phase of the three-phase DC/AC unit 130, the three-phase DC/AC unit 130 may be drive blocked, while the switching unit 140 corresponding to the fault in the three-phase DC/AC unit 130 is turned off, so that the connection between the non-faulty phase of the three-phase DC/AC unit 130 and the grid 150 is maintained on. After the switching unit 140 disconnects the fault phase from the power grid 150, the non-fault phase of the three-phase DC/AC unit 130 is deactivated to be blocked for restarting, thereby enabling the three-phase DC/AC unit 130 to perform the two-phase operation mode.
For further understanding, the following description may be made with reference to specific embodiments. Since the A, B and C three phases of the three-phase DC/AC unit 130 are processed in the same manner at the time of fault isolation, specific explanation can be made based on the occurrence of a fault in the a phase of the three-phase DC/AC unit 130.
Specifically, assume that device S in three-phase DC/AC unit 130 a1 If an open circuit fault occurs, then in the device S a1 After the failure detection is successful, all the devices of the three-phase DC/AC unit 130 may be connected (S a1 ~S c2 ) To perform driving blocking and simultaneously to connect the contactor T a Disconnection is performed so that the fault phase of the three-phase DC/AC unit 130 is disconnected from the power grid 150. Contact T a After the disconnection, the non-fault phase B and the non-fault phase C of the three-phase DC/AC unit 130 may be restarted, so that the three-phase DC/AC unit 130 may operate in the two-phase operation mode.
3. A short circuit fault occurs for the DC/DC unit 120.
As shown in fig. 6 to 10, when the DC/DC unit 120 has a short-circuit fault, the DC/DC unit 120 and the three-phase DC/AC unit 130 may be all driven and blocked, and the switching unit 140 may be all opened, so that the connection of the three-phase DC/AC unit 130 and the power grid 150 is all disconnected. At this time, the second bypass unit 220 may be turned on, so that the DC/DC unit 120 may form a fusing circuit through the second bypass unit 220, and the fusing circuit may fuse the corresponding fuse input to the DC/DC unit 120. After the fuse is blown, the first bypass unit 210 is closed and conducted, and one phase of the three-phase DC/AC unit 130 is used as an isolated phase, and is kept connected and disconnected with the power grid 150; then, the switching unit 140 corresponding to the non-isolation of the three-phase DC/AC unit 130 is closed and restarted, so that the three-phase DC/AC unit 130 can perform two-phase operation to continue the normal operation of the battery energy storage system, and meanwhile, the faulty DC/DC unit 120 can be isolated by the connection conduction of the isolation phase and the first bypass unit 210.
For further understanding, the following description may be made with reference to specific embodiments. As shown in fig. 6 to 10, the DC/DC unit 120 includes devices S connected to each other DC1 And S is DC2 While a fuse F is connected between the input of the DC/DC unit 120 and the battery 110 DC . Since the two devices of the DC/DC unit 120 have the same processing manner during fault isolation, a specific explanation can be made by that one of the devices of the DC/DC unit 120 fails; among them, the a phase of the three-phase DC/AC unit 130 may be used as an isolated phase.
Specifically, as shown in fig. 6, it is assumed that the device S of the DC/DC unit 120 DC1 Short-circuit fault occurs in the device S DC1 After the failure detection is successful, all the devices of the three-phase DC/AC unit 130 may be connected (S a1 ~S c2 ) And all devices of the DC/DC unit 120 (S DC1 And S is DC2 ) Drive blocking is carried out while all contactors (T a ~T c ) And (5) disconnecting. Both second bypass units 220 may then be turned onSo that short-circuited device S DC1 Fuse F DC The battery 110, the second bypass unit 220 and the power grid 150 are communicated with each other to form a fusing circuit (thickened line shown in fig. 6), and the battery 110 supplies power to the fusing circuit so that the fuse F DC Is fused. Fuse F to be fused DC After the fusing, the two second bypass units 220 may be disconnected again; the first bypass unit 210 is then turned on, and the contactor T b And T c And closing, and restarting the non-isolated phases B and C of the three-phase DC/AC unit 130, wherein the positive end of the battery 110 is directly connected with the phase A bridge arm of the three-phase DC/AC unit 130 through the first bypass unit 210, so that the three-phase DC/AC unit 130 works in a two-phase operation mode of B and C operation.
4. An open circuit fault occurs for the DC/DC unit 120.
One of the phases of the three-phase DC/AC unit 130 may be previously taken as an isolated phase; thus, when the DC/DC unit 120 has an open circuit fault, all of the DC/DC unit 120 and the three-phase DC/AC unit 130 may be driven and blocked, and at the same time, the switching unit 140 corresponding to the isolated phase output is opened, so that the connection between the one phase of the three-phase DC/AC unit 130, which is the isolated phase, and the power grid 150 is disconnected. After the switch unit 140 disconnects the isolated phase from the power grid 150, the first bypass unit 210 may be turned on, and the non-isolated phase of the three-phase DC/AC unit 130 may be unblocked for restarting operation, so that the three-phase DC/AC unit 130 performs the two-phase operation mode.
For further understanding, the following description may be made with reference to specific embodiments. Since the two devices of the DC/DC unit 120 have the same processing manner during fault isolation, a specific explanation can be made by that one of the devices of the DC/DC unit 120 fails; among them, the a phase of the three-phase DC/AC unit 130 may be used as an isolated phase.
Specifically, assume that device S of DC/DC unit 120 DC1 If an open circuit fault occurs, then in the device S DC1 After the failure detection is successful, all the devices of the three-phase DC/AC unit 130 may be connected (S a1 ~S c2 ) The DC/DC unit 120With devices (S) DC1 And S is DC2 ) To perform driving blocking and simultaneously to connect the contactor T a And (5) disconnecting. Contact T a After the disconnection, the first bypass unit 210 may be turned on, and the non-isolated phases B and C of the three-phase DC/AC unit 130 may be restarted, so that the three-phase DC/AC unit 130 may operate in the two-phase operation mode.
In this embodiment, when fault isolation of the DC/DC unit 120 is performed, it must be able to connect with the first bypass unit 210 as an isolated phase of the DC/DC unit 120. The specific arrangement of the separator phase is as follows.
Embodiment one: as shown in fig. 7, one end of the first bypass unit 210 is connected to the positive terminal of the battery 110, and the other end of the first bypass unit 210 is connected to the a-phase leg of the three-phase DC/AC unit 130, so that the a-phase leg of the three-phase DC/AC unit 130 forms an isolation phase required for fault isolation of the DC/DC unit 120.
Embodiment two: as shown in fig. 8, one end of the first bypass unit 210 is connected to the positive end of the battery 110, and the other end of the first bypass unit 210 is connected to the B-phase leg of the three-phase DC/AC unit 130, so that the B-phase leg of the three-phase DC/AC unit 130 forms an isolation phase required for fault isolation of the DC/DC unit 120.
Embodiment III: as shown in fig. 9, one end of the first bypass unit 210 is connected to the positive end of the battery 110, and the other end of the first bypass unit 210 is connected to the C-phase leg of the three-phase DC/AC unit 130, so that the C-phase leg of the three-phase DC/AC unit 130 forms an isolation phase required for fault isolation of the DC/DC unit 120.
Embodiment four: as shown in fig. 10, one end of the first bypass unit 210 is connected to the positive end of the battery 110, and the other end of the first bypass unit 210 is connected to the a-phase, B-phase and C-phase legs of the three-phase DC/AC unit 130, respectively, so that when the DC/DC unit 120 needs to perform fault isolation, the first bypass unit 210 is communicated with any one of the phase legs of the three-phase DC/AC unit 130 to form a required isolation phase.
It will be appreciated that for the embodiments one to three described above, such asAs shown in fig. 7 to 9, the first bypass unit 210 includes a thyristor T DC Thyristor T DC Can be connected with the positive terminal of the battery 110, the thyristor T DC The other end of (a) may be connected with a leg required for any one phase of the three-phase DC/AC unit 130. For the fourth embodiment described above, as shown in fig. 10, the first bypass unit 210 includes three thyristors T DCa 、T DCb And T DCc Three thyristors T DCa 、T DCb And T DCc Is connected to the positive terminal of the battery 110, three thyristors T DCa 、T DCb And T DCc The other end of the three-phase DC/AC unit 130 is correspondingly connected with the A phase bridge arm, the B phase bridge arm and the C phase bridge arm respectively; the system of the fourth embodiment is more selective than those of the first to third embodiments, but the corresponding design cost is also increased. The first to fourth embodiments can meet the actual needs, and the specific setting mode can be selected according to the actual needs of those skilled in the art.
It should also be appreciated that the thyristor included in the first bypass unit 210 is in a normally open state, i.e., when the battery energy storage system is operating normally, the first bypass unit 210 is kept in an off state by the normally open state of the thyristor; when fault isolation of the DC/DC unit 120 is performed, the first bypass unit 210 remains on by the closing of the thyristor.
In this embodiment, the DC/DC unit 120 is used to control the DC bus voltage of the system, and the three-phase DC/AC unit 130 is used to control the system power flow; specifically, the outer ring of the DC/DC unit 120 is a bus voltage ring, and the inner ring is a current ring; the outer loop of the three-phase DC/AC unit 130 is a power loop and the inner loop is a current loop. As shown in fig. 5 and 6, when the three-phase DC/AC unit 130 performs two-phase operation, the directions of the current commands of the B phase and the C phase are opposite, and are 30 ° different from the voltage phase angle of the corresponding power grid 150. The given currents of the B phase and the C phase when the three-phase DC/AC unit 130 performs two-phase operation can be set to be i 1 * And i 2 * And let the active power loop output of the three-phase DC/AC unit 130 be I d * The reactive power loop output is I q * The method comprises the steps of carrying out a first treatment on the surface of the The given currents are i 1 * And i 2 * The following operation formula is provided:
。
。
where ωt represents the product of the angular frequency ω and time t, i.e. the phase.
The foregoing has outlined the basic principles, features, and advantages of the present application. It will be understood by those skilled in the art that the present application is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present application, and various changes and modifications may be made therein without departing from the spirit and scope of the application, which is defined by the appended claims. The scope of the application is defined by the appended claims and equivalents thereof.

Claims (10)

1. A battery energy storage system with fault tolerance function comprises a battery, a DC/DC unit and a three-phase DC/AC unit which are connected in sequence; the method is characterized in that: the three-phase DC/AC unit is suitable for being connected with the battery and the power grid through the isolation module respectively;
when a certain phase of the three-phase DC/AC unit fails, the isolation module is suitable for disconnecting the failed phase output of the three-phase DC/AC unit, so that the three-phase DC/AC unit performs two-phase operation of fault isolation;
when the DC/DC unit fails, the isolation module is suitable for disconnecting the output of one phase of the three-phase DC/AC unit to serve as an isolation phase, so that the three-phase DC/AC unit performs two-phase operation; the isolation phase is suitable for being directly connected with the battery through the isolation module, so that the fault DC/DC unit is isolated.
2. The fault tolerant battery energy storage system of claim 1, wherein: the isolation module comprises a switch unit and a first bypass unit; each phase output of the three-phase DC/AC unit is connected with a power grid through the switch unit; the positive end of the battery is connected with a bridge arm of the three-phase DC/AC unit through the first bypass unit which is normally open;
when an open circuit fault occurs to one phase of the three-phase DC/AC unit, the switch unit is suitable for disconnecting the fault phase of the three-phase DC/AC unit from the power grid, so that the three-phase DC/AC unit performs two-phase operation;
when the DC/DC unit has an open-circuit fault, the switch unit is suitable for disconnecting the isolation phase from the power grid, and then the positive end of the battery is directly connected with the isolation phase through the closed conduction of the first bypass unit.
3. The fault tolerant battery energy storage system of claim 2, wherein: when an open circuit fault occurs in a certain phase of the three-phase DC/AC unit, the three-phase DC/AC unit is suitable for driving and blocking, and meanwhile, the switch unit disconnects the fault phase of the three-phase DC/AC unit from the power grid; after the switching unit is completely disconnected, the three-phase DC/AC unit is suitable for restarting the non-fault phase to perform two-phase operation;
when the DC/DC unit has an open-circuit fault, the three-phase DC/AC unit and the DC/DC unit are both driven and blocked, and the switch unit disconnects the isolation phase from the power grid; after the switching unit is completely disconnected, the non-isolated phase of the three-phase DC/AC unit is suitable for restarting, and the first bypass unit is conducted at the same time.
4. The fault tolerant battery energy storage system of claim 2, wherein: the isolation module further comprises a pair of second bypass units and a plurality of fuses; the positive end and the negative end of the three-phase DC/AC unit are connected with the power grid through the second bypass unit; each phase output of the three-phase DC/AC unit and the input of the DC/DC unit are connected with the fuse;
when a short circuit fault occurs in one phase of the three-phase DC/AC unit, the fault phase of the three-phase DC/AC unit forms a fusing loop through the second bypass unit, and then the fuse corresponding to the output of the fault phase is fused, so that the output of the fault phase is disconnected;
when the DC/DC unit has a short-circuit fault, the DC/DC unit is suitable for forming a fusing loop through the second bypass unit, so that the corresponding fuse is fused through the input of the DC/DC unit, and meanwhile, the isolation phase is disconnected with the power grid through the switch unit.
5. The fault tolerant battery energy storage system of claim 4, wherein: when a short-circuit fault occurs in one phase of the three-phase DC/AC unit, the three-phase DC/AC unit is firstly subjected to driving blocking, and the switch unit corresponding to the non-fault is disconnected; then fusing the fuse corresponding to the fault to disconnect the output of the fault phase, and restarting the non-fault phase of the three-phase DC/AC unit after completing fusing;
when the DC/DC unit has short-circuit fault, the DC/DC unit and the three-phase DC/AC unit are firstly driven and blocked, and the switch unit is completely disconnected; and then fusing the fuse corresponding to the DC/DC unit, closing and conducting the first bypass unit after fusing, and closing the switch unit corresponding to the non-isolation of the three-phase DC/AC unit.
6. The fault tolerant battery energy storage system of any of claims 1-5, wherein: the given current of the three-phase DC/AC unit in two-phase operation is i 1 * And i 2 * And setting the active power loop output of the three-phase DC/AC unit as I d * The reactive power loop output is I q * The method comprises the steps of carrying out a first treatment on the surface of the Then:
；
；
where ωt represents the product of the angular frequency ω and time t, i.e. the phase.
7. The fault tolerant battery energy storage system of claim 2, wherein: the first bypass unit comprises a thyristor, and the positive end of the battery is suitable for being connected with any phase bridge arm of the three-phase DC/AC unit through the thyristor.
8. The fault tolerant battery energy storage system of claim 2, wherein: the first bypass unit comprises three thyristors, and the positive end of the battery is suitable for being connected with the three-phase bridge arm of the three-phase DC/AC unit through the thyristors.
9. The fault tolerant battery energy storage system of claim 4, wherein: the second bypass unit is in a normally open state and comprises thyristors, and the positive end and the negative end of the three-phase DC/AC unit are connected with the power grid through the corresponding thyristors respectively.
10. The fault tolerant battery energy storage system of claim 9, wherein: the second bypass unit further comprises a current limiting resistor connected in series with the thyristor.
CN202310851365.4A 2023-07-12 2023-07-12 Battery energy storage system with fault tolerance function Active CN116565927B (en)

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