CN115833206B - Energy storage conversion circuit, converter submodule and energy storage conversion system - Google Patents
Energy storage conversion circuit, converter submodule and energy storage conversion system Download PDFInfo
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- 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
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Abstract
The application provides an energy storage conversion circuit, a converter sub-module and an energy storage conversion system, and relates to the technical field of energy storage converters. Therefore, the combination of the H-bridge three-level circuit and the H-bridge two-level circuit replaces the H-bridge two-level circuit structure used in the traditional cascade energy storage system, and the influence on the service life of the battery pack caused by double frequency fluctuation in the charging and discharging process of the cascade energy storage conversion system is solved.
Description
Technical Field
The present application relates to the field of energy storage converters, and in particular, to an energy storage conversion circuit, a converter sub-module, and an energy storage conversion system.
Background
When new energy sources such as wind power, photovoltaic and the like are utilized for generating power, the generated power has randomness and intermittence, and some challenges are brought to safe and stable operation of a power grid. And this problem can be solved by providing a cascade type large-capacity energy storage system.
However, the existing cascade high-capacity energy storage system mostly adopts an H-bridge structure, and the structure has more defects, so that the charge and discharge power of the battery can be caused to be subjected to double frequency fluctuation, and the service life of the battery pack can be accelerated by the double frequency instantaneous active power fluctuation; each H bridge module needs one battery pack, and the number of the battery packs is relatively large; the H bridge is a two-level topological structure, the output harmonic wave is higher, and the power fluctuation of the charge and discharge current is larger.
Based on the above, the application provides a novel energy storage conversion circuit.
Disclosure of Invention
In view of the above, the present application provides a tank conversion circuit, which aims to solve the problems of high output current ripple and high harmonic in the existing tank conversion circuit.
In a first aspect, the present application provides a tank conversion circuit comprising: the first H bridge two-level circuit and the first H bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel.
Optionally, the energy storage conversion circuit further includes:
the second H-bridge two-level circuit, the second H-bridge three-level circuit, the third H-bridge two-level circuit, the third H-bridge three-level circuit and the transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
Optionally, a first switch is connected in series between the positive terminal of the first end of the first H-bridge three-level circuit and the negative terminal of the first end;
a second switch is connected in series between the positive end of the second H-bridge three-level circuit and the negative end of the second end;
and a third switch is connected in series between the positive end of the second end of the third H-bridge three-level circuit and the negative end of the second end.
Optionally, the second end of the first H-bridge three-level circuit is connected with a first direct current supporting capacitor and a second direct current supporting capacitor;
the first end of the second H-bridge three-level circuit is connected with a third direct current supporting capacitor and a fourth direct current supporting capacitor;
a first end of the third H-bridge three-level circuit is connected with a fifth direct current supporting capacitor and a sixth direct current supporting capacitor;
the first direct current support capacitor, the second direct current support capacitor, the third direct current support capacitor, the fourth direct current support capacitor, the fifth direct current support capacitor and the sixth direct current support capacitor are used for storing and releasing electric energy.
Optionally, a tap of a primary winding of the transformer is connected with midpoints of the first direct current supporting capacitor and the second direct current supporting capacitor;
a tap of a first secondary winding of the transformer is connected with the midpoints of the third direct-current supporting capacitor and the fourth direct-current supporting capacitor;
and a tap of a second secondary winding of the transformer is connected with the midpoints of the fifth direct-current supporting capacitor and the sixth direct-current supporting capacitor.
Optionally, the first H-bridge three-level circuit is:
the first T-shaped H-bridge three-level circuit or the first active clamp I-shaped H-bridge three-level circuit;
the second H-bridge three-level circuit is as follows:
the second T-shaped H-bridge three-level circuit or the second active clamp I-shaped H-bridge three-level circuit;
the third H-bridge three-level circuit is as follows:
a third T-type H-bridge three-level circuit or a third active clamp I-type H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first T-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second T-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third T-shaped H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first active clamp I-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second active clamp I-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third active clamp I-type H-bridge three-level circuit.
In a second aspect, the present application provides an energy storage converter sub-module comprising: the first H bridge two-level circuit and the first H bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel.
Optionally, the energy storage converter sub-module further comprises a second H-bridge two-level circuit, a second H-bridge three-level circuit, a third H-bridge two-level circuit, a third H-bridge three-level circuit and a transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
Optionally, a first switch is connected in series between the positive terminal of the first end of the first H-bridge three-level circuit and the negative terminal of the first end;
a second switch is connected in series between the positive end of the second H-bridge three-level circuit and the negative end of the second end;
and a third switch is connected in series between the positive end of the second end of the third H-bridge three-level circuit and the negative end of the second end.
Optionally, the second end of the first H-bridge three-level circuit is connected with a first direct current supporting capacitor and a second direct current supporting capacitor;
the first end of the second H-bridge three-level circuit is connected with a third direct current supporting capacitor and a fourth direct current supporting capacitor;
a first end of the third H-bridge three-level circuit is connected with a fifth direct current supporting capacitor and a sixth direct current supporting capacitor;
the first direct current support capacitor, the second direct current support capacitor, the third direct current support capacitor, the fourth direct current support capacitor, the fifth direct current support capacitor and the sixth direct current support capacitor are used for storing and releasing electric energy.
Optionally, a tap of a primary winding of the transformer is connected with midpoints of the first direct current supporting capacitor and the second direct current supporting capacitor;
a tap of a first secondary winding of the transformer is connected with the midpoints of the third direct-current supporting capacitor and the fourth direct-current supporting capacitor;
and a tap of a second secondary winding of the transformer is connected with the midpoints of the fifth direct-current supporting capacitor and the sixth direct-current supporting capacitor.
Optionally, the first H-bridge three-level circuit is:
the first T-shaped H-bridge three-level circuit or the first active clamp I-shaped H-bridge three-level circuit;
the second H-bridge three-level circuit is as follows:
the second T-shaped H-bridge three-level circuit or the second active clamp I-shaped H-bridge three-level circuit;
the third H-bridge three-level circuit is as follows:
a third T-type H-bridge three-level circuit or a third active clamp I-type H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first T-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second T-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third T-shaped H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first active clamp I-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second active clamp I-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third active clamp I-type H-bridge three-level circuit.
In a third aspect, the present application provides an energy storage conversion system comprising at least one energy storage converter sub-module, a reactor;
the energy storage converter sub-module is the energy storage converter sub-module described in the second aspect;
after cascade connection, the at least one energy storage converter submodule is connected with an alternating current power grid through the reactor in a delta connection or star connection mode.
Optionally, after the at least one energy storage converter submodule is cascaded, connecting the ac power grid through the reactor includes:
the first end of the first H-bridge three-level circuit of the energy storage converter sub-module is connected with a first phase of an alternating current power grid through the reactor;
the second end of the second H-bridge three-level circuit of the energy storage converter sub-module is connected with a second phase of an alternating current power grid through the reactor;
and the second end of the third H-bridge three-level circuit of the energy storage converter sub-module is connected with a third phase of an alternating current power grid through the reactor.
The application provides an energy storage conversion circuit. The circuit comprises a first H-bridge two-level circuit and a first H-bridge three-level circuit, wherein a first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, a second end of the first H-bridge three-level circuit is used for being connected with a first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with an energy storage unit in parallel. Therefore, the combination of the H-bridge three-level circuit and the H-bridge two-level circuit replaces the H-bridge two-level circuit structure used in the traditional energy storage system, and the influence on the service life of the battery pack caused by double frequency fluctuation in the charge and discharge process of the energy storage conversion system is solved.
Drawings
In order to more clearly illustrate this embodiment or the technical solutions of the prior art, the drawings that are required for the description of the embodiment or the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic topology diagram of a cascaded energy storage converter according to an embodiment of the present application;
fig. 2 is a schematic diagram of a tank conversion circuit according to an embodiment of the present application;
FIG. 3 is a schematic diagram of another energy storage conversion circuit according to an embodiment of the present application;
FIG. 4 is a schematic diagram of another energy storage conversion circuit according to an embodiment of the present application;
FIG. 5 is a schematic diagram of another energy storage conversion circuit according to an embodiment of the present application;
FIG. 6 is a schematic diagram of an energy storage conversion system according to an embodiment of the present application;
fig. 7 is a schematic diagram of another energy storage conversion system according to an embodiment of the present application.
Detailed Description
The high-capacity centralized energy storage system not only can stabilize power fluctuation caused by large-scale access of new energy and assist in solving the problem of low-electric energy ride through, but also can realize peak clipping, valley filling, peak regulation and frequency modulation of power grid dispatching requirements, and the existing high-capacity centralized energy storage converter mainly adopts an H-bridge structure and is based on a modularized multi-level converter in a cascading mode. The typical topology of the existing cascade energy storage converter is shown in fig. 1, each phase of bridge arm of the cascade type H-bridge battery energy storage converter (PCS) is formed by cascading N converter units based on an H bridge, the direct current side of each H-bridge power unit is formed by connecting a battery energy storage unit with a capacitor in parallel, each phase of bridge arm is connected into an alternating current power grid through a grid-connected reactance, capacity expansion of the energy storage converter is achieved, and meanwhile the output electric energy level of the energy storage converter is improved. Cascaded H-bridge converters are widely used due to their modular configuration, good harmonic characteristics and high efficiency. Meanwhile, since the H-bridge converter needs to provide an isolated direct current power supply for each H-bridge module, a plurality of battery units can be integrated to realize medium-high voltage operation.
However, in the prior art, the high-capacity energy storage converter is realized by adopting a cascade H bridge mode, so that the battery charging and discharging power is subjected to double frequency fluctuation, the service life attenuation of the battery pack is accelerated by the double frequency instantaneous active power fluctuation, and the H bridge is of a two-level topological structure, so that the output harmonic wave is higher, and the charging and discharging current ripple wave is large. Based on the above drawbacks, the present application proposes a new circuit structure.
Referring to fig. 2, fig. 2 is a schematic diagram of an energy storage conversion circuit according to an embodiment of the present application, including a first H-bridge two-level circuit and a first H-bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel.
The first end of the first H-bridge three-level circuit is connected into a first phase of an alternating current power grid through ports X1 and X2, a first switch is connected in series between the positive end of the first H-bridge three-level circuit and the negative end of the first H-bridge three-level circuit, the first H-bridge three-level circuit is a bypass switch, the second end of the first H-bridge three-level circuit is connected with a first direct current supporting capacitor and a second direct current supporting capacitor and used for storing and releasing electric energy, a tap of a primary winding of a transformer is connected with the middle points of the first direct current supporting capacitor and the second direct current supporting capacitor, the first end of the first H-bridge two-level circuit is connected with an energy storage unit in parallel to charge or discharge the energy storage unit, and the first T-shaped H-bridge three-level circuit or the first active clamp I-shaped H-bridge three-level circuit is connected with the first T-shaped H-bridge three-level circuit. When the first H-bridge three-level circuit is a first T-type H-bridge three-level circuit, the energy storage conversion circuit further includes electronic switches TXa1 to TXa4, TXb1 to TXb4, and TX9 to TX12, and the specific working mode is as follows:
first define an ideal switching function S Ji As shown in formula (1):
U X is the voltage across ports X1 and X2, U 1 Is C 1 Capacitor voltage, U 2 Is C 2 Capacitor voltage, U N For the grid voltage, I N For grid current (the direction to the grid is defined as the opposite direction). Each bridge arm has three equivalent states of 1,0 and 1, two bridge arms have 9 switch combinations and 9 working modes, and the following table shows the working states of a T-shaped H-bridge three-level circuit.
Table 1: working state of T-shaped H-bridge three-level circuit
Working mode 1: (S) Xa ，S Xb ) = (1, 1), electronic switch T Xa1 ,T Xb1 On, other electronic switches are off, port voltage U X ＝0。
Working mode 2: (S) Xa ，S Xb ) = (1, 0), electronic switch T Xa1, T Xb3 ,T Xb4 On, other electronic switches are off, port voltage U X ＝U 1 Voltage U across network side inductance L L ＝U N -U X ，U N Greater than (less than) U 1 At the time, net side current I N Will increase (decrease), I N When the direction is forward (reverse), the capacitor C 1 Charge (discharge), and the capacitors C1 and C2 charge (discharge) the battery.
Working mode 3: (S) Xa ，S Xb ) = (1, -1), electronic switch T Xa1 ,T Xb2 On, other electronic switches are off, port voltage U X ＝U 1 +U 2 Voltage U across network side inductance L L ＝U N -U X Due to U N Less than U 1 +U 2 At the time, net side current I N Will gradually decrease, I N When the direction is forward (reverse), the capacitors C1 and C2 are charged (discharged), and the capacitors C1 and C2 charge (discharge) the battery.
Working mode 4: (S) Xa ，S Xb ) = (0, 1), electronic switch T Xa3 ,T Xa4 ,T Xb1 On, other electronic switches are off, port voltage U X ＝-U 1 Voltage U across network side inductance L L ＝U N -U X ，U N Greater than (less than) -U 1 At the time, net side current I N Will increase (decrease), I N When the direction is forward (reverse), the capacitor C 1 The capacitors C1 and C2 discharge (charge) the battery.
Working mode 5: (S) Xa ，S Xb ) = (0, 0), electronic switch T Xa3 ,T Xa4 ，T Xb3 ,T Xb4 On, other electronic switches are off, port voltage U X ＝0。
Working mode 6: (S) Xa ，S Xb ) = (0, -1), electronic switch T Xa3 ,T Xa4 ,T Xb2 On, other electronic switches are off, port voltage U X ＝U 2 Voltage U across network side inductance L L ＝U N -U X ，U N Greater than (less than) U 1 At the time, net side current I N Will increase (decrease), I N When the direction is forward (reverse), the capacitor C 2 Charge (discharge), and the capacitors C1 and C2 charge (discharge) the battery.
Other modes of operation may be analyzed by table 1 and are not described here.
When the first H-bridge tri-level circuit is a first active clamp I-type H-bridge tri-level circuit, referring to fig. 3, fig. 3 is a schematic diagram of another energy storage conversion circuit provided in an embodiment of the present application, and compared with fig. 2, the energy storage conversion circuit includes electronic switches TXa1 to TXa6, TXb1 to TXb6, TX13 to TX16, and the specific working mode is as follows:
defining an ideal switching function S Ji As shown in formula (2):
U X is the voltage across ports X1 and X2, U 1 Is C 1 Capacitor voltage, U 2 Is C 2 Capacitor voltage, U N For the grid voltage, I N For grid current (the direction to the grid is defined as the opposite direction). Each bridge arm has three equivalent states of 1,0 and 1, two bridge arms have 9 switch combinations and 9 working modes, and the following table 2 is an active clamp type I H bridge three-level working state.
Table 2: three-level working state of active clamp I-type H bridge
Working mode 2: (S) Xa ，S Xb ) = (1, 0), electronic switch T Xa1 ,T Xa2 ,T Xa6 ,T Xb2 ,T Xb5 (or T) Xb3 ,T Xb6 ) On, other electronic switches are off, port voltage U X ＝U 1 Voltage U across network side inductance L L ＝U N -U X Wherein U is N For the grid voltage, U N Greater than (less than) U 1 At the time, net side current I N Will increase (decrease), I N When the direction is forward (reverse), the capacitor C 1 Charge (discharge), capacitor C1 and C2 pair batteryCharging (discharging).
Working mode 3: (S) Xa ，S Xb ) = (1, -1), electronic switch T Xa1 ,T Xa2 ,T Xa6, T Xb3, T Xb4, T Xb5, On, other electronic switches are off, port voltage U X ＝U 1 +U 2 Voltage U across network side inductance L L ＝U N -U X Wherein U is N For mains voltage, due to U N Less than U 1 +U 2 At the time, net side current I N Will gradually decrease, I N When the direction is forward (reverse), the capacitors C1 and C2 are charged (discharged), and the capacitors C1 and C2 charge (discharge) the battery.
Working mode 6: (S) Xa ，S Xb ) = (0, -1), electronic switch T Xa2 ,T Xa5 (or T) Xa3 ,T Xa6 ),T Xb3 ,T Xb4 ,T Xb5 On, other electronic switches are off, port voltage U X ＝U 2 Voltage U across network side inductance L L ＝U N -U X Wherein U is N For the grid voltage, U N Greater than (less than) U 1 At the time, net side current I N Will increase (decrease), I N When the direction is forward (reverse), the capacitor C 2 Charge (discharge), and the capacitors C1 and C2 charge (discharge) the battery.
Other modes of operation may be analyzed by table 2 and are not described here.
In another implementation manner of the embodiment of the present application, the energy storage conversion circuit further includes:
the second H-bridge two-level circuit, the second H-bridge three-level circuit, the third H-bridge two-level circuit, the third H-bridge three-level circuit and the transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
Referring to fig. 4 and fig. 5, fig. 4 is a schematic diagram of another energy storage conversion circuit according to an embodiment of the present application, and fig. 5 is a schematic diagram of another energy storage conversion circuit according to an embodiment of the present application.
Fig. 4 is composed of three-phase symmetrical X-phases (electronic switches TXa1 to TXa4, TXb1 to TXb4, TX9 to TX 12), Y-phases (electronic switches TYa1 to TYa4, TYb1 to TYb4, TY9 to TY 12), Z-phases (electronic switches TZa1 to TZa4, TZb1 to TZb4, TZ9 to TZ 12), three-winding high-frequency transformers, direct-current supporting capacitors C1 to C6, mechanical bypass switches K1 to K3, and the like, and ports (B +, B-) connect the batteries.
The transformer is a high-frequency isolation transformer, three windings are adopted, each winding is provided with a middle tap, a certain leakage inductance is designed, the middle tap is connected with a midpoint of a capacitor, the high-frequency transformer and an H-bridge two-level unit can be equivalently a bidirectional active DC/DC converter, the power can be controlled in a T-shaped H-bridge three-level mode and a battery in a bidirectional mode, and the transformer has an upper capacitor voltage equalizing function and a lower capacitor voltage equalizing function.
In fig. 5, the three-phase symmetrical circuit is composed of three phases of X phases (electronic switches TXa 1-TXa 6, TXb 1-TXb 6, TX 13-TX 16), Y phases (electronic switches TYa 1-TYa 6, TYb 1-TYb 6, TY 13-TY 16), Z phases (electronic switches TZa 1-TZa 6, TZb 1-TZb 6, TZ 13-TZ 16), a three-winding high-frequency transformer, direct-current supporting capacitors C1-C6, mechanical bypass switches K1-K3 and the like, and ports (B+ and B-) are connected with a battery. The high-frequency isolation transformer adopts three windings, each winding is provided with a middle tap, a certain leakage inductance is designed, the middle tap is connected with a midpoint of a capacitor, the high-frequency transformer and the H-bridge two-level unit can be equivalently a bidirectional active DC/DC converter, the bidirectional control of power between the three levels of the active clamp I-type H-bridge and a battery can be realized, and the high-frequency isolation transformer has the function of equalizing voltage of the upper capacitor and the lower capacitor.
The application also provides an energy storage converter submodule which comprises a first H-bridge two-level circuit and a first H-bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel.
In one implementation manner of the embodiment of the application, the energy storage converter submodule further comprises a second H-bridge two-level circuit, a second H-bridge three-level circuit, a third H-bridge two-level circuit, a third H-bridge three-level circuit and a transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
In one implementation manner of the embodiment of the application, a first switch is connected in series between a positive end of a first end of the first H-bridge three-level circuit and a negative end of the first end;
a second switch is connected in series between the positive end of the second H-bridge three-level circuit and the negative end of the second end;
and a third switch is connected in series between the positive end of the second end of the third H-bridge three-level circuit and the negative end of the second end.
In one implementation manner of the embodiment of the application, a first direct current supporting capacitor and a second direct current supporting capacitor are connected to the second end of the first H-bridge three-level circuit;
the first end of the second H-bridge three-level circuit is connected with a third direct current supporting capacitor and a fourth direct current supporting capacitor;
a first end of the third H-bridge three-level circuit is connected with a fifth direct current supporting capacitor and a sixth direct current supporting capacitor;
the first direct current support capacitor, the second direct current support capacitor, the third direct current support capacitor, the fourth direct current support capacitor, the fifth direct current support capacitor and the sixth direct current support capacitor are used for storing and releasing voltage.
In one implementation manner of the embodiment of the application, a tap of a primary winding of the transformer is connected with midpoints of the first direct current supporting capacitor and the second direct current supporting capacitor;
a tap of a first secondary winding of the transformer is connected with the midpoints of the third direct-current supporting capacitor and the fourth direct-current supporting capacitor;
and a tap of a second secondary winding of the transformer is connected with the midpoints of the fifth direct-current supporting capacitor and the sixth direct-current supporting capacitor.
In one implementation manner of the embodiment of the present application, the first H-bridge three-level circuit is:
the first T-shaped H-bridge three-level circuit or the first active clamp I-shaped H-bridge three-level circuit;
the second H-bridge three-level circuit is as follows:
the second T-shaped H-bridge three-level circuit or the second active clamp I-shaped H-bridge three-level circuit;
the third H-bridge three-level circuit is as follows:
a third T-type H-bridge three-level circuit or a third active clamp I-type H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first T-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second T-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third T-shaped H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first active clamp I-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second active clamp I-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third active clamp I-type H-bridge three-level circuit.
The application also provides an energy storage conversion system which comprises at least one energy storage converter sub-module and a reactor.
At least one energy storage converter submodule is connected with an alternating current power grid through the reactor in a delta connection or star connection mode after being cascaded, wherein the specific connection mode is that a first end of a first H-bridge three-level circuit of the energy storage converter submodule is connected with a first phase of the alternating current power grid through the reactor;
the second end of the second H-bridge three-level circuit of the energy storage converter sub-module is connected with a second phase of an alternating current power grid through the reactor;
and the second end of the third H-bridge three-level circuit of the energy storage converter sub-module is connected with a third phase of an alternating current power grid through the reactor.
The specific connection mode is shown in fig. 6 and 7, the ports of the X1 and X2 of all the energy storage converter submodules are cascaded to form an A phase, the terminals of the Y1 and Y2 are cascaded to form a B phase, the terminals of the Z1 and Z2 are cascaded to form a C phase, each SM submodule is connected with a group of battery packs, a system formed by the cascading of the submodules and the battery packs can be directly connected into a three-phase 10KV power grid through a reactor, fig. 6 is in star connection, and fig. 7 is in triangle connection. Under normal conditions, the mechanical bypass switches K1-K3 in each sub-module are all in an off state, and when the electronic switch T x1 ～T x12 ，T y1 ～T t12 ，T z1 ～T z12 The fault-time bypass switches K1-K3 are closed when faults occur, the fault submodule is in a fault bypass state, and the rest submodules are recombined to continue to operate. The connection mode of each sub-module can be regarded as a three-phase H-bridge structure, and a three-phase static coordinate system (A, B, C) of three-phase alternating voltage and current can be converted into direct current coordinate systems (d and q) synchronously rotating at the fundamental frequency of a power grid. Three-phase network voltage U a 、U b 、U c Performing abc/dq conversion to obtain DC component U under dq rotation coordinate system d 、U q The equation under the dq coordinate system is:
three-phase current I a 、I b 、I c Performing abc/dq conversion to obtain DC component under dq rotation coordinate system
I d 、I q The equation under the dq coordinate system is:
the power equation can be found as:
P＝U d *I d +U q *I q
Q＝U q *I d -U d *I q
wherein P is active power, Q is reactive power, and U is d 、U q And I d 、I q Since the direct current power is adopted, the active power P and the reactive power Q are also direct current power, the charging and discharging power at the direct current side basically has no double frequency fluctuation under the condition of symmetric power grid, and the charging and discharging ripple wave is very small.
The current cascading multi-level system connected with the 10KV power grid needs 45 sub-modules and 45 battery packs, the scheme needs fewer sub-modules and battery packs, the number of the battery packs is greatly reduced, and each battery pack is matched with a corresponding battery management system and an electric device, so that the number of the battery packs is reduced, and the cost and the occupied area of part of the battery systems can be saved. The structures in fig. 6 and 7 have no power doubling fluctuation, do not need to additionally increase a power doubling inhibition strategy, and have simple control strategy.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments for relevant points. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present application without undue burden.
It is noted that relational terms such as first and second, and the like are 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. Moreover, 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 one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
It should be further noted that, in the present specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for the apparatus and device embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference is made to the description of the method embodiments for relevant points. The apparatus and device embodiments described above are merely illustrative, wherein elements illustrated as separate elements may or may not be physically separate, and elements presented as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present application without undue burden.
The foregoing is only one specific embodiment of the present application, but the scope of the present application is not limited thereto, and any changes or substitutions easily contemplated by those skilled in the art within the technical scope of the present application should be included in the scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims (8)
1. A tank conversion circuit, comprising: the first H bridge two-level circuit and the first H bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel;
the second H-bridge two-level circuit, the second H-bridge three-level circuit, the third H-bridge two-level circuit, the third H-bridge three-level circuit and the transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
2. The tank circuit of claim 1, wherein a first switch is connected in series between a positive terminal of a first terminal of the first H-bridge tri-level circuit and a negative terminal of the first terminal;
a second switch is connected in series between the positive end of the second H-bridge three-level circuit and the negative end of the second end;
and a third switch is connected in series between the positive end of the second end of the third H-bridge three-level circuit and the negative end of the second end.
3. The energy storage conversion circuit according to claim 1, wherein a first direct current supporting capacitor and a second direct current supporting capacitor are connected to a second end of the first H-bridge three-level circuit;
the first end of the second H-bridge three-level circuit is connected with a third direct current supporting capacitor and a fourth direct current supporting capacitor;
a first end of the third H-bridge three-level circuit is connected with a fifth direct current supporting capacitor and a sixth direct current supporting capacitor;
the first direct current support capacitor, the second direct current support capacitor, the third direct current support capacitor, the fourth direct current support capacitor, the fifth direct current support capacitor and the sixth direct current support capacitor are used for storing and releasing electric energy.
4. A tank circuit according to claim 3, wherein the tap of the primary winding of the transformer is connected to the midpoint of the first and second dc support capacitors;
a tap of a first secondary winding of the transformer is connected with the midpoints of the third direct-current supporting capacitor and the fourth direct-current supporting capacitor;
and a tap of a second secondary winding of the transformer is connected with the midpoints of the fifth direct-current supporting capacitor and the sixth direct-current supporting capacitor.
5. The tank circuit of claim 1 wherein the first H-bridge tri-level circuit is:
the first T-shaped H-bridge three-level circuit or the first active clamp I-shaped H-bridge three-level circuit;
the second H-bridge three-level circuit is as follows:
the second T-shaped H-bridge three-level circuit or the second active clamp I-shaped H-bridge three-level circuit;
the third H-bridge three-level circuit is as follows:
a third T-type H-bridge three-level circuit or a third active clamp I-type H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first T-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second T-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third T-shaped H-bridge three-level circuit;
when the first H-bridge three-level circuit is the first active clamp I-type H-bridge three-level circuit, the second H-bridge three-level circuit is the second active clamp I-type H-bridge three-level circuit; the third H-bridge three-level circuit is the third active clamp I-type H-bridge three-level circuit.
6. An energy storage converter sub-module, comprising: the first H bridge two-level circuit and the first H bridge three-level circuit;
the first end of the first H-bridge three-level circuit is used for being connected with a first phase of an alternating current power grid, the second end of the first H-bridge three-level circuit is used for being connected with the first end of the first H-bridge two-level circuit, and the first end of the first H-bridge two-level circuit is connected with the energy storage unit in parallel;
further comprises: the second H-bridge two-level circuit, the second H-bridge three-level circuit, the third H-bridge two-level circuit, the third H-bridge three-level circuit and the transformer;
the second end of the first H bridge two-level circuit is connected with the primary winding of the transformer;
the first secondary winding of the transformer is connected with the first end of the second H-bridge two-level circuit, the second end of the second H-bridge two-level circuit is connected with the first end of the second H-bridge three-level circuit, and the second end of the second H-bridge three-level circuit is used for being connected with the second phase of the alternating current power grid;
the second secondary winding of the transformer is connected with the first end of the third H-bridge two-level circuit, the second end of the third H-bridge two-level circuit is connected with the first end of the third H-bridge three-level circuit, and the second end of the third H-bridge three-level circuit is used for being connected with a third phase of the alternating current power grid.
7. An energy storage conversion system, the system comprising at least one energy storage converter sub-module and a reactor;
the energy storage converter sub-module is the energy storage converter sub-module of claim 6;
after cascade connection, the at least one energy storage converter submodule is connected with an alternating current power grid through the reactor in a delta connection or star connection mode.
8. The system of claim 7, wherein connecting the ac power grid through the reactor after the at least one energy storage converter submodule passes through the cascade comprises:
the first end of the first H-bridge three-level circuit of the energy storage converter sub-module is connected with a first phase of an alternating current power grid through the reactor;
the second end of the second H-bridge three-level circuit of the energy storage converter sub-module is connected with a second phase of an alternating current power grid through the reactor;
and the second end of the third H-bridge three-level circuit of the energy storage converter sub-module is connected with a third phase of an alternating current power grid through the reactor.
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| JP2015233394A (en) * | 2014-06-10 | 2015-12-24 | 株式会社東芝 | Vehicle power conversion apparatus |
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| EP3785363A4 (en) * | 2018-04-25 | 2022-01-12 | Socovar S.E.C | Voltage level multiplier module for multilevel power converters |
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| CN112868172A (en) * | 2018-11-26 | 2021-05-28 | 华为技术有限公司 | Three-level power conversion system and method |
| CN113098307A (en) * | 2021-04-16 | 2021-07-09 | 南京工程学院 | Series-parallel hybrid multilevel converter with energy storage function and dual phase-shifting PWM control method |
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