CN114389296A - Energy storage system grid-connection and off-grid switching device - Google Patents
Energy storage system grid-connection and off-grid switching device Download PDFInfo
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- CN114389296A CN114389296A CN202210193756.7A CN202210193756A CN114389296A CN 114389296 A CN114389296 A CN 114389296A CN 202210193756 A CN202210193756 A CN 202210193756A CN 114389296 A CN114389296 A CN 114389296A
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- energy storage
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- frequency isolation
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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
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
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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
- H02M3/33569—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 several active switching elements
- H02M3/33576—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 several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33584—Bidirectional converters
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Abstract
The invention discloses a grid-connected and off-grid switching device of an energy storage system, which comprises an energy storage device, a bidirectional high-frequency isolation DC/DC converter, a bidirectional AC/DC converter and a grid-connected and off-grid switch; one end of the energy storage device is connected with one end of the bidirectional high-frequency isolation DC/DC converter; the other end of the bidirectional high-frequency isolation DC/DC converter is connected with one end of the bidirectional AC/DC converter; the other end of the bidirectional AC/DC converter is connected with the grid-connected and off-grid switcher; the bidirectional high-frequency isolation DC/DC converter is arranged to replace a power frequency transformer connected between the energy storage converter and the grid-connected and off-grid switching device, isolation between a battery and a power grid is achieved, the bidirectional high-frequency isolation DC/DC converter works at high frequency, conversion efficiency is high, the required size and weight are small under the same power requirement, the energy storage converter with the bidirectional high-frequency isolation DC/DC converter is combined with the grid-connected and off-grid switching device, high efficiency and light weight of a grid-connected and off-grid energy storage system can be achieved, and the development trend of a power supply system is met.
Description
Technical Field
The invention relates to the field of circuits, in particular to a grid-connected and off-grid switching device of an energy storage system.
Background
When the energy storage system works in a grid-connected mode, the power grid charges and discharges the battery and supplies power to the load; when the power grid is powered off, the load is required to be ensured not to interrupt power supply, and the battery is switched to supply power to the load through the energy storage converter (PCS) and the grid-connected and off-grid switching device (STS).
In order to protect an electric energy transmission circuit, an isolation and boosting device is needed to be connected between an energy storage converter (PCS) and a grid-connected and off-grid switching device (STS), a power frequency transformer is usually adopted in the prior art, but the power frequency transformer is large in size and low in efficiency, and facilities such as a cabinet and a fan need to be installed in a matched mode, so that the economic cost is high.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: provided is an energy storage system grid-connected and off-grid switching device which can realize high efficiency and light weight of a grid-connected and off-grid energy storage system.
In order to solve the technical problems, the invention adopts a technical scheme that:
a grid-connected and off-grid switching device of an energy storage system comprises an energy storage device, a bidirectional high-frequency isolation DC/DC converter, a bidirectional AC/DC converter and a grid-connected and off-grid switcher;
one end of the energy storage device is connected with one end of the bidirectional high-frequency isolation DC/DC converter;
the other end of the bidirectional high-frequency isolation DC/DC converter is connected with one end of the bidirectional AC/DC converter;
and the other end of the bidirectional AC/DC converter is connected with the grid-connected and off-grid switcher.
From the above description, the beneficial effects of the present invention are: according to the energy storage system grid-connected and off-grid switching device provided by the invention, the bidirectional high-frequency isolation DC/DC converter is arranged in the energy storage converter to replace a power frequency transformer connected between the energy storage converter and the grid-connected and off-grid switching device in the prior art, so that the isolation between a battery and a power grid is realized.
Drawings
Fig. 1 is a structural diagram of an energy storage system grid-connected and off-grid switching device according to an embodiment of the present invention;
fig. 2 is a block diagram of another energy storage system grid-connected and off-grid switching device according to an embodiment of the invention;
fig. 3 is a structural diagram of a bidirectional high-frequency isolation DC/DC converter according to an embodiment of the present invention.
Description of reference numerals:
CB1, first circuit breaker; CB2, second circuit breaker; CB3, third circuit breaker; c1, a first capacitance; c2, a second capacitor; q1, a first MOS tube; q2 and a second MOS tube; q3 and a third MOS tube; q4 and a fourth MOS tube; q5 and a fifth MOS tube; q6 and a sixth MOS tube; q7, seventh MOS pipe; q8, eighth MOS pipe; q9, ninth MOS pipe; q10, tenth MOS pipe; q11 and an eleventh MOS tube; q12, twelfth MOS pipe; l1, a first inductor; l2, a second inductor; l3, third inductance; c31, a first third capacitance; c32, a second third capacitance; c33, a third capacitance; t1, a first high frequency isolation transformer; t2, a second high frequency isolation transformer; t3, third high frequency isolation transformer.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
Referring to fig. 1 to 3, an energy storage system grid-connected and off-grid switching device includes an energy storage, a bidirectional high-frequency isolation DC/DC converter, a bidirectional AC/DC converter, and a grid-connected and off-grid switcher;
one end of the energy storage device is connected with one end of the bidirectional high-frequency isolation DC/DC converter;
the other end of the bidirectional high-frequency isolation DC/DC converter is connected with one end of the bidirectional AC/DC converter;
and the other end of the bidirectional AC/DC converter is connected with the grid-connected and off-grid switcher.
From the above description, the beneficial effects of the present invention are: according to the energy storage system grid-connected and off-grid switching device provided by the invention, the bidirectional high-frequency isolation DC/DC converter is arranged in the energy storage converter to replace a power frequency transformer connected between the energy storage converter and the grid-connected and off-grid switching device in the prior art, so that the isolation between a battery and a power grid is realized.
Further, the bidirectional high-frequency isolation DC/DC converter comprises a first-stage conversion unit, a transformation unit and a second-stage conversion unit;
one end of the first-stage conversion unit is connected with one end of the energy storage device;
one end of the voltage transformation unit is connected with the other end of the first-stage transformation unit;
one end of the second-stage transformation unit is connected with the other end of the voltage transformation unit;
one end of the bidirectional AC/DC converter is connected with the other end of the second-stage conversion unit.
As can be seen from the above description, by providing the first-stage conversion unit and the second-stage conversion unit, a high-frequency inversion or rectification function can be realized according to the flowing direction of the electric energy, and by providing the voltage transformation unit, high-frequency conversion of different voltages can be realized according to the flowing direction of the electric energy, thereby realizing bidirectional flow of energy.
Further, the first-stage conversion unit comprises a first capacitor and three first switch groups;
the three first switch groups are connected in parallel;
the first capacitor and the energy accumulator are connected in parallel;
the first switch group is connected with the first capacitor in parallel;
the first switch group comprises two MOS tubes which are connected in series.
It can be known from the above description that, include first switch group through setting up first order transform unit, can rely on the frequency and the state of controlling each switch, accomplish the regulation operation to voltage gain, and set up the switch that first switch group includes and be the MOS pipe, do benefit to synchronous rectification, thereby realize the two-way flow of electric energy, can reduce the volume and the cost of system by a wide margin in the application occasion that needs the two-way flow of energy, simultaneously through setting up first electric capacity, can filter the ripple current of energy storage ware side, be favorable to voltage stabilization.
Further, the second-stage conversion unit comprises a second capacitor and three second switch groups;
the three pairs of second switch groups are connected in parallel;
the second capacitor is connected in parallel with the bidirectional AC/DC converter;
the second switch group is connected with the second capacitor in parallel;
the second switch group is composed of two MOS tubes connected in series.
It can be known from the above description that, including the second switch group through setting up the second level converting unit, can rely on the frequency and the state of controlling each switch, accomplish the regulation operation to the voltage gain to the switch that sets up the second switch group and include is the MOS pipe, does benefit to synchronous rectification, thereby realizes the two-way flow of electric energy, can reduce the volume and the cost of system by a wide margin in the application occasion that needs the two-way flow of energy, simultaneously through setting up the second electric capacity, can filter the ripple current of two-way AC/DC converter side, is favorable to voltage stabilization.
Further, the transformation unit comprises three high-frequency isolation transformers and three resonance units;
the first ends of the primary windings of the three high-frequency isolation transformers are correspondingly connected with one end of each of the three resonance units;
the second ends of the primary windings of the three high-frequency isolation transformers are connected together;
the other ends of the three resonance units are correspondingly connected between the two MOS tubes connected in series of the three first switch groups one by one;
the first ends of the secondary windings of the three high-frequency isolation transformers are correspondingly connected with the two MOS tubes of the three second switch groups in series one by one;
and the second ends of the secondary windings of the three high-frequency isolation transformers are connected together.
As can be seen from the above description, by providing the high frequency isolation transformer, the energy storage and the two-side circuit of the grid-connected/off-grid switching device are not directly conducted, and the high frequency electric energy is transmitted from one side to the other side through electromagnetic induction, so that the two-side electrical insulation is realized, the protection effect on the two-side circuit is achieved, and the high frequency inversion effect is improved by providing the resonance unit.
Further, the resonance unit includes an inductance and a third capacitance;
one end of the inductor is connected with the first end of the primary winding of the high-frequency isolation transformer;
the other end of the inductor is connected with one end of the third capacitor;
the other end of the third capacitor is connected between the two MOS tubes of the first switch group which are connected in series.
As can be seen from the above description, the LLC resonant converter has the advantages of high switching frequency, low turn-off loss, high efficiency, light weight, small size, low electromagnetic interference noise, low switching stress, and the like; meanwhile, three phases are connected in parallel in a staggered mode, the capacity of each phase voltage can be automatically adjusted, each phase current is adjusted, the currents are naturally superposed and cancelled, output current ripples are reduced, and the capacity of equipment is expanded.
Further, the system also comprises a load, a first alternating current EMC filter, a second alternating current EMC filter and a power grid;
one end of the first alternating current EMC filter is connected with one end of the grid-connected and off-grid switcher and one end of the load respectively;
the other end of the first alternating current EMC filter is connected with one end of the power grid;
one end of the load is connected to one end of the second alternating current EMC filter;
the other end of the second alternating current EMC filter is connected with the other end of the grid-connected and off-grid switcher.
According to the description, the load is respectively connected with the power grid and the grid-connected and grid-disconnected switcher, when the system is in a grid-connected mode, the power grid supplies power to the load, when the power grid is powered off, the grid-disconnected switcher supplies power to the load, the load is guaranteed not to be powered off, and meanwhile the first alternating current EMC filter and the second alternating current EMC filter are arranged to respectively stabilize the voltage of the power grid side and the voltage of the load side.
Further, the device also comprises a first circuit breaker;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the first circuit breaker.
Further, a second circuit breaker is also included;
the first ac EMC filter is connected to the load through the second circuit breaker.
Further, a third circuit breaker is also included;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the third circuit breaker.
It can be known from the above description that through setting up first circuit breaker as electric wire netting side circuit breaker, the second circuit breaker is as maintenance bypass switch circuit breaker, and the third circuit breaker is as load side circuit breaker, when closed second circuit breaker, when breaking off first circuit breaker and third circuit breaker, can realize overhauing energy storage converter inside, the load is direct to be supplied power by the electric wire netting.
The grid-connected and off-grid switching device of the energy storage system can be applied to any type of grid-connected and off-grid energy storage system, and is described in the following by specific embodiments:
the first embodiment of the invention is as follows:
a grid-connected and off-grid switching device of an energy storage system comprises an energy storage device, a bidirectional high-frequency isolation DC/DC converter, a bidirectional AC/DC converter and a grid-connected and off-grid switcher;
one end of the energy storage device is connected with one end of the bidirectional high-frequency isolation DC/DC converter;
the other end of the bidirectional high-frequency isolation DC/DC converter is connected with one end of the bidirectional AC/DC converter;
the other end of the bidirectional AC/DC converter is connected with the grid-connected and off-grid switcher;
the bidirectional high-frequency isolation DC/DC converter and the bidirectional AC/DC converter can jointly form an energy storage converter, the bidirectional high-frequency isolation DC/DC converter can convert direct current into high-frequency pulse through high frequency, and then the high-frequency pulse is rectified into direct current after isolation, the conversion frequency is higher and is usually about 100KHz, so that an additional power frequency transformer is not needed, the bidirectional AC/DC converter can invert the direct current output by the bidirectional high-frequency isolation DC/DC converter into alternating current in high frequency, or rectify the alternating current output by the grid-connected and off-grid switcher into direct current;
in an alternative embodiment, the energy storage converter may be modular, and support multi-module parallel and grid-connected/off-grid switch connection as shown in fig. 1, wherein the energy storage device includes a plurality of groups of battery packs, the plurality of groups of battery packs are connected with a plurality of groups of bidirectional high-frequency isolation DC/DC converters in a one-to-one correspondence, the plurality of groups of bidirectional high-frequency isolation DC/DC converters are connected with a plurality of groups of bidirectional AC/DC converters in a one-to-one correspondence, and the plurality of groups of bidirectional AC/DC converters are connected with the grid-connected/off-grid switch;
the plurality of groups of energy accumulators are connected to the bus through the independent bidirectional isolation conversion devices, the differences among different energy accumulators are not influenced mutually any more, and even the energy accumulators with different properties can be combined for use;
in addition, the tower type energy storage converter is also suitable for the energy storage system and is connected with the off-grid switching device as shown in fig. 2.
The second embodiment of the invention is as follows:
on the basis of the first embodiment, the structure of the grid-connected and off-grid switching device of the energy storage system is further defined in the embodiment;
please refer to fig. 1 or fig. 2, further comprising a load, a first ac EMC filter, a second ac EMC filter and a grid;
one end of the first alternating current EMC filter is connected with one end of the grid-connected and off-grid switcher and one end of the load respectively;
the other end of the first alternating current EMC filter is connected with one end of the power grid;
one end of the load is further connected with one end of the second alternating current EMC filter;
the other end of the second alternating current EMC filter is connected with the other end of the grid-connected and off-grid switcher;
the grid-connected and off-grid switcher adopts a static selector switch STS, and the static selector switch STS comprises SCR switches which are respectively arranged on phase-A electricity, phase-B electricity, phase-C electricity and phase-N electricity;
the working principle of the energy storage system grid-connected and off-grid switching device is as follows:
when the grid-connected mode is adopted, the power grid charges the energy storage device through the grid-connected and off-grid switcher through the bidirectional AC/DC converter and the bidirectional high-frequency isolation DC/DC converter and supplies power to a load, or receives power grid dispatching, and the energy storage device discharges through the bidirectional high-frequency isolation DC/DC converter and the bidirectional AC/DC converter and feeds back the discharged power to the power grid through the grid-connected and off-grid switcher and supplies power to the load; when the power grid is powered off, the off-grid switcher detects the power grid power off, gives a switching instruction to close SCR switches arranged in phase A power, phase B power, phase C power and phase N power, and the bidirectional high-frequency isolation DC/DC converter and the bidirectional AC/DC converter are switched from a charging state to a discharging state to supply power to a load so as to prevent the load from being powered off; after the power grid is recovered, the grid-connected switcher is switched to a grid-connected operation mode, and the bidirectional high-frequency isolation DC/DC converter and the bidirectional AC/DC converter are switched from a discharging state to a charging state to supply power to the energy accumulator; therefore, seamless switching of grid connection and grid disconnection is realized, and the peak clipping and valley filling can be realized, so that the electricity fee difference is earned.
The third embodiment of the invention is as follows:
on the basis of the first embodiment, the connection among the grid-connected and off-grid switcher, the power grid and the load is further defined as follows:
referring to fig. 1 or fig. 2, the circuit breaker further includes a first circuit breaker CB 1;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the first circuit breaker;
also included is a second circuit breaker CB 2;
the first ac EMC filter is connected to the load through the second circuit breaker.
Also included is a third circuit breaker CB 3;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the third circuit breaker;
the CB1 is used as a power grid side circuit breaker, the CB2 is used as a maintenance bypass switch circuit breaker, the CB3 is used as a load side circuit breaker, when the CB2 is closed and the CB1 and the CB3 are opened, the interiors of the bidirectional high-frequency isolation DC/DC converter and the bidirectional AC/DC converter can be overhauled, and the load is directly supplied with power by a power grid, so that the uninterrupted power supply of the load is ensured.
The fourth embodiment of the invention is as follows:
on the basis of any one of the first to third embodiments, the present embodiment further defines the structure of the bidirectional high-frequency isolation DC/DC converter;
referring to fig. 3, the bidirectional high-frequency isolation DC/DC converter includes a first-stage conversion unit, a transformation unit, and a second-stage conversion unit;
one end of the first-stage conversion unit is connected with one end of the energy storage device;
one end of the voltage transformation unit is connected with the other end of the first-stage transformation unit;
one end of the second-stage transformation unit is connected with the other end of the voltage transformation unit;
one end of the bidirectional AC/DC converter is connected with the other end of the second-stage conversion unit.
In an alternative embodiment, the first stage conversion unit includes a first capacitor C4 and three first switch groups;
the three pairs of first switch groups are connected in parallel;
the first capacitor C1 and the energy storage device are connected in parallel;
the first switch group is connected in parallel with the first capacitor C1;
preferably, the first switch group consists of two MOS transistors connected in series;
specifically, in this embodiment, the first switch group is composed of a first MOS transistor Q1 and a second MOS transistor Q2 connected in series, wherein an S-pole of the first MOS transistor Q1 is connected to a D-pole of the second MOS transistor Q2, a D-pole of the first MOS transistor Q1 is connected to the first end of the first capacitor C1, and an S-pole of the second MOS transistor Q2 is connected to the second end of the first capacitor C1;
the second first switch group consists of a third MOS transistor Q3 and a fourth MOS transistor Q4 which are connected in series, wherein the S pole of the third MOS transistor Q3 is connected with the D pole of the fourth MOS transistor Q4, the D pole of the third MOS transistor Q3 is connected with the first end of a first capacitor C1, and the S pole of the fourth MOS transistor Q4 is connected with the second end of the first capacitor C1;
the third first switch group consists of a fifth MOS transistor Q5 and a sixth MOS transistor Q6, wherein the S pole of the fifth MOS transistor Q5 is connected with the D pole of the sixth MOS transistor Q6, the D pole of the fifth MOS transistor Q5 is connected with the first end of the first capacitor C1, and the S pole of the sixth MOS transistor Q6 is connected with the second end of the first capacitor C1;
the second-stage conversion unit comprises a second capacitor C2 and three second switch groups;
the three pairs of second switch groups are connected in parallel;
the second capacitor C2 is connected in parallel with the grid-connected and off-grid switcher;
the second switch group is connected in parallel with the second capacitor C2;
preferably, the second switch group consists of two MOS transistors connected in series;
specifically, in this embodiment, the first second switch group is composed of a seventh MOS transistor Q7 and an eighth MOS transistor Q8 connected in series, wherein an S-pole of the seventh MOS transistor Q7 is connected to a D-pole of the eighth MOS transistor Q8, a D-pole of the seventh MOS transistor Q7 is connected to the first end of the second capacitor C2, and an S-pole of the eighth MOS transistor Q8 is connected to the second end of the second capacitor C2;
the second switch group is composed of a ninth MOS transistor Q9 and a tenth MOS transistor Q10 which are connected in series, wherein the S pole of the ninth MOS transistor Q9 is connected to the D pole of the tenth MOS transistor Q10, the D pole of the ninth MOS transistor Q9 is connected to the first end of the second capacitor C2, and the S pole of the tenth MOS transistor Q10 is connected to the second end of the second capacitor C2;
the third second switch group is composed of an eleventh MOS transistor Q11 and a twelfth MOS transistor Q12, wherein the S-pole of the eleventh MOS transistor Q11 is connected to the D-pole of the twelfth MOS transistor Q12, the D-pole of the eleventh MOS transistor Q11 is connected to the first end of the second capacitor C2, and the S-pole of the twelfth MOS transistor Q12 is connected to the second end of the second capacitor C2;
in an alternative embodiment, the transforming unit comprises three high frequency isolation transformers and three resonant units;
the first ends of the primary windings of the three high-frequency isolation transformers are correspondingly connected with one end of each of the three resonance units;
the second ends of the primary windings of the three high-frequency isolation transformers are connected together;
the other ends of the three resonance units are correspondingly connected with the two MOS tubes of the three first switch groups which are connected in series one by one;
the first ends of the secondary windings of the three high-frequency isolation transformers are correspondingly connected with the two MOS tubes of the three second switch groups in series one by one;
the second ends of the secondary windings of the three high-frequency isolation transformers are connected together;
preferably, the resonance unit includes an inductance and a third capacitance;
one end of the inductor is connected with the first end of the primary winding of the high-frequency isolation transformer;
the other end of the inductor is connected with one end of the third capacitor;
the other end of the third capacitor is connected with the two MOS tubes of the first switch group which are connected in series;
specifically, in this embodiment, one end of a first third capacitor C31 is connected between the first MOS transistor Q1 and the second MOS transistor Q2, the other end of the first third capacitor C31 is connected to one end of a first inductor L1, the other end of the first inductor L1 is connected to a first end of a primary winding of a first high-frequency isolation transformer T1, and a first end of a secondary winding of the first high-frequency isolation transformer T1 is connected between the seventh MOS transistor Q7 and the eighth MOS transistor Q8;
one end of a second third capacitor C32 is connected between the third MOS transistor Q3 and the fourth MOS transistor Q4, the other end of the second third capacitor C32 is connected with one end of a second inductor L8, the other end of the second inductor L8 is connected with the first end of the primary winding of a second high-frequency isolation transformer T2, and the first end of the secondary winding of the second high-frequency isolation transformer T2 is connected between the ninth MOS transistor Q9 and the tenth MOS transistor Q10;
one end of a third capacitor C33 is connected between the fifth MOS transistor Q5 and the sixth MOS transistor Q6, the other end of the third capacitor C33 is connected to one end of a third inductor L3, the other end of the third inductor L3 is connected to the first end of the primary winding of a third high-frequency isolation transformer T3, and the first end of the secondary winding of the third high-frequency isolation transformer T3 is connected between the eleventh MOS transistor Q11 and the twelfth MOS transistor Q12;
the second ends of the primary windings of the three high-frequency isolation transformers T1, T2 and T3 are connected together, the second ends of the secondary windings of the three high-frequency isolation transformers T1, T2 and T3 are connected together, and the first end of the primary winding and the first end of the secondary winding are homonymous ends.
The fifth embodiment of the invention is as follows:
on the basis of the fourth embodiment, the device further comprises a controller for controlling the on and off of each MOS tube;
the MOS tubes connected with the positive electrode of the first capacitor C1 in the three first switch groups are respectively in one-to-one correspondence with the MOS tubes connected with the positive electrode of the second capacitor C2 in the three second switch groups, and the MOS tubes connected with the negative electrode of the first capacitor C1 in the three first switch groups are respectively in one-to-one correspondence with the MOS tubes connected with the negative electrode of the second capacitor C2 in the three second switch groups;
specifically, the controller is configured to control the MOS transistor connected to the anode of the second capacitor C2 in each second switch group and the controllable switch connected to the anode of the first capacitor C1 in the corresponding first switch group to be in a synchronous rectification state; controlling the MOS tube connected with the cathode of the second capacitor C2 in each second switch group and the MOS tube connected with the cathode of the first capacitor C1 in the corresponding first switch group to be in a synchronous rectification state;
when energy flows in the forward direction, the primary side works in a series resonance mode, the secondary side works in a synchronous rectification mode, when the energy flows in the forward direction, the secondary side works in the series resonance mode, the primary side works in the synchronous rectification mode, so that the bidirectional flow of electric energy is realized, and because the circuit structures of the first-stage conversion unit and the second-stage conversion unit are the same, the circuits work in the same mode no matter the flow direction of the electric energy is in the forward direction or the reverse direction, the control of the two flow directions can adopt the same control strategy, and the control algorithm is simplified;
and three of them resonance circuit adopts symmetrical LLC structure, has improved the resonance symmetry, and the autonomy accomplishes flow equalizing, has improved the symmetry that the electric current flows between two converting circuit, has further reduced ripple current, satisfies powerful output requirement more easily.
In summary, according to the grid-connected and off-grid switching device of the energy storage system provided by the invention, the bidirectional high-frequency isolation DC/DC converter is arranged in the energy storage converter, wherein the bidirectional high-frequency isolation DC/DC converter comprises the high-frequency isolation transformer, instead of a power frequency transformer connected between the energy storage converter and the grid-connected and off-grid switching device in the prior art, isolation between a battery and a power grid and bidirectional flow of energy are realized, meanwhile, the bidirectional high-frequency isolation DC/DC converter works at high frequency, the conversion efficiency is higher, the required volume and weight are smaller under the same power requirement, and the ripple is effectively reduced by adopting a three-phase staggered parallel structure, the volume of a filter capacitor can be reduced, meanwhile, heat can be dispersed into three high-frequency isolation transformers, and the device is more suitable for the output requirement of high power; in summary, the energy storage converter with the bidirectional high-frequency isolation DC/DC conversion device is combined with the grid-connected and off-grid switching device, so that the weight and the volume of the grid-connected and off-grid energy storage system can be reduced, the electric energy transmission efficiency of the system is improved, the high efficiency and the light weight of the grid-connected and off-grid energy storage system are realized, the obvious technical advantages and economic value are realized, and the energy storage converter can be widely applied to medium-power grid-connected and off-grid energy storage systems.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (10)
1. The grid-connected and off-grid switching device of the energy storage system is characterized by comprising an energy storage device, a bidirectional high-frequency isolation DC/DC converter, a bidirectional AC/DC converter and a grid-connected and off-grid switch;
one end of the energy storage device is connected with one end of the bidirectional high-frequency isolation DC/DC converter;
the other end of the bidirectional high-frequency isolation DC/DC converter is connected with one end of the bidirectional AC/DC converter;
and the other end of the bidirectional AC/DC converter is connected with the grid-connected and off-grid switcher.
2. The grid-connected and off-grid switching device of the energy storage system according to claim 1, wherein the bidirectional high-frequency isolation DC/DC converter comprises a first-stage conversion unit, a transformation unit and a second-stage conversion unit;
one end of the first-stage conversion unit is connected with one end of the energy storage device;
one end of the voltage transformation unit is connected with the other end of the first-stage transformation unit;
one end of the second-stage transformation unit is connected with the other end of the voltage transformation unit;
one end of the bidirectional AC/DC converter is connected with the other end of the second-stage conversion unit.
3. The grid-connected and off-grid switching device of the energy storage system according to claim 2, wherein the first-stage conversion unit comprises a first capacitor and three first switch groups;
the three first switch groups are connected in parallel;
the first capacitor and the energy accumulator are connected in parallel;
the first switch group is connected with the first capacitor in parallel;
the first switch group comprises two MOS tubes which are connected in series.
4. The grid-connected and off-grid switching device of the energy storage system according to claim 2 or 3, wherein the second-stage conversion unit comprises a second capacitor and three second switch groups;
the three pairs of second switch groups are connected in parallel;
the second capacitor is connected in parallel with the bidirectional AC/DC converter;
the second switch group is connected with the second capacitor in parallel;
the second switch group is composed of two MOS tubes connected in series.
5. The grid-connected and off-grid switching device of an energy storage system according to claim 4, wherein the voltage transformation unit comprises three high-frequency isolation transformers and three resonance units;
the first ends of the primary windings of the three high-frequency isolation transformers are correspondingly connected with one end of each of the three resonance units;
the second ends of the primary windings of the three high-frequency isolation transformers are connected together;
the other ends of the three resonance units are correspondingly connected between the two MOS tubes connected in series of the three first switch groups one by one;
the first ends of the secondary windings of the three high-frequency isolation transformers are correspondingly connected with the two MOS tubes of the three second switch groups in series one by one;
and the second ends of the secondary windings of the three high-frequency isolation transformers are connected together.
6. The on-grid and off-grid switching device of an energy storage system according to claim 5, wherein the resonant unit comprises an inductor and a third capacitor;
one end of the inductor is connected with the first end of the primary winding of the high-frequency isolation transformer;
the other end of the inductor is connected with one end of the third capacitor;
the other end of the third capacitor is connected between the two MOS tubes of the first switch group which are connected in series.
7. The on-grid and off-grid switching device of the energy storage system according to any one of claims 1 to 6, further comprising a load, a first alternating current EMC filter, a second alternating current EMC filter and a grid;
one end of the first alternating current EMC filter is connected with one end of the grid-connected and off-grid switcher and one end of the load respectively;
the other end of the first alternating current EMC filter is connected with one end of the power grid;
one end of the load is connected to one end of the second alternating current EMC filter;
the other end of the second alternating current EMC filter is connected with the other end of the grid-connected and off-grid switcher.
8. The grid-connected and off-grid switching device of an energy storage system according to claim 7, further comprising a first circuit breaker;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the first circuit breaker.
9. The grid-connected and off-grid switching device of an energy storage system according to claim 7, further comprising a second circuit breaker;
the first ac EMC filter is connected to the load through the second circuit breaker.
10. The grid-connected and off-grid switching device of an energy storage system according to claim 7, further comprising a third circuit breaker;
the first alternating current EMC filter is connected with the grid-connected and off-grid switcher through the third circuit breaker.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210193756.7A CN114389296A (en) | 2022-03-01 | 2022-03-01 | Energy storage system grid-connection and off-grid switching device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210193756.7A CN114389296A (en) | 2022-03-01 | 2022-03-01 | Energy storage system grid-connection and off-grid switching device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114389296A true CN114389296A (en) | 2022-04-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210193756.7A Pending CN114389296A (en) | 2022-03-01 | 2022-03-01 | Energy storage system grid-connection and off-grid switching device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114389296A (en) |
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2022
- 2022-03-01 CN CN202210193756.7A patent/CN114389296A/en active Pending
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