CN220254149U - Micro-group string photovoltaic grid-connected inversion system - Google Patents
Micro-group string photovoltaic grid-connected inversion system Download PDFInfo
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- CN220254149U CN220254149U CN202321399504.6U CN202321399504U CN220254149U CN 220254149 U CN220254149 U CN 220254149U CN 202321399504 U CN202321399504 U CN 202321399504U CN 220254149 U CN220254149 U CN 220254149U
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Abstract
The utility model discloses a micro-group string photovoltaic grid-connected inversion system, which comprises: the micro-group string unit 11 is used for connecting a plurality of groups of photovoltaic modules in series and parallel to form a micro-group string array; a direct current bus 20, configured to connect the micro-string units 11 in parallel to the micro-string grid-connected inverter 30, where the micro-string grid-connected inverter 30 includes multiple sets of DC/DC conversion circuits and DC/AC conversion circuits; the DC/DC conversion circuit is used for controlling the micro-group string units 11 which are electrically connected, so as to realize a boosting function; and the DC/AC conversion circuit is used for converting direct current output by the DC/DC conversion circuit into alternating current and combining the alternating current with a power grid. The micro-group string units input direct current into the micro-group string grid-connected inverter through the direct current bus, the micro-group string grid-connected inverter controls the micro-group string units which are electrically connected, the input direct current is adjusted and converted into alternating current and then is combined into a power grid, and the micro-group string units form a photovoltaic array, so that the wooden barrel effect is reduced, the system cost is reduced, and meanwhile, the direct current is lower than 120V to meet the building safety voltage.
Description
Technical Field
The utility model relates to the technical field of photovoltaic grid-connected inversion, in particular to a micro-group string photovoltaic grid-connected inversion system.
Background
At present, a household photovoltaic grid-connected inverter mainly comprises a string inverter and a micro inverter, wherein the string inverter is used for connecting a plurality of photovoltaic modules in series to form a high-voltage string inverter, the voltage is higher than 120V building safety voltage, and the structure has the advantages of low cost and potential safety hazard due to direct current high voltage. Due to the wooden barrel effect, the generated energy of each string of photovoltaic modules is greatly reduced when the partial shadow is blocked or the parameters of the modules are inconsistent. The micro grid-connected inverter is used for controlling each photovoltaic module to be connected with the inverter, so that direct-current high voltage does not exist, the safety problem is avoided, the partial shadow wooden barrel effect is eliminated due to the fact that each module is controlled, but the micro inverter is high in cost, and further popularization and application are affected.
Disclosure of Invention
In order to solve the technical problems in the background technology, the utility model provides a micro-group string photovoltaic grid-connected inverter system.
The utility model provides a micro-group string photovoltaic grid-connected inversion system, which comprises:
the micro-group string unit 11 is used for connecting a plurality of groups of photovoltaic modules in series and parallel to form a micro-group string array;
a direct current bus 20, configured to connect the micro-string units 11 in parallel to the micro-string grid-connected inverter 30, where the micro-string grid-connected inverter 30 includes multiple sets of DC/DC conversion circuits and DC/AC conversion circuits;
the DC/DC conversion circuit is used for controlling the micro-group string units 11 which are electrically connected, so as to realize a boosting function;
the DC/AC conversion circuit is used for converting direct current output by the DC/DC conversion circuit into alternating current and combining the alternating current with a power grid;
wherein, a plurality of groups of micro-group string units 11 are correspondingly connected in parallel with one end of a plurality of groups of DC/DC conversion circuits one by one through a DC bus 20; the multiple groups of DC/DC conversion circuits are electrically connected, and then are electrically connected through the DC/AC conversion circuits to be integrated into a power grid.
Preferably, "the electrical connection between the plurality of sets of DC/DC conversion circuits" is specifically: the DC/DC conversion circuits are connected in parallel, and include, but are not limited to, a full-bridge phase-shifting circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
Preferably, "the electrical connection between the plurality of sets of DC/DC conversion circuits" is specifically: the DC/DC conversion circuits are connected in series, and the DC/DC conversion circuits comprise, but are not limited to, a boost circuit, a buck-boost circuit, a full-bridge phase-shifting circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
Preferably, the DC/AC conversion circuit includes, but is not limited to, a three-phase full-bridge inverter circuit, a single-phase half-bridge inverter circuit, a single-phase full-bridge inverter circuit, a three-phase half-bridge inverter circuit, a multi-level inverter.
Preferably, the full-bridge phase-shifting circuit comprises a primary side H-bridge converter, a parallel resonance inductor, a full-bridge phase-shifting conversion secondary side half-bridge rectifying unit, a transformer and an input capacitor C1n; the full-bridge phase-shifting conversion circuit primary side H-bridge converter consists of switching tubes Q1n-Q4 n; l1n is a parallel resonant inductor of the full-bridge phase-shifting conversion circuit; the full-bridge phase-shifting transformation secondary side half-bridge rectifying unit consists of a diode D1n, a diode D2n, a capacitor C2n and a capacitor C3 n.
Preferably, the boost circuit includes an input capacitor C1m, an inductor L1m, a switching tube Q2m, and an output capacitor C2m, where the input capacitor C1m and the inductor L1m are connected in series and then connected in parallel with the switching tube Q1m, and the switching tube Q2m and the output capacitor C2m are connected in series and then connected in parallel with the switching tube Q1 m.
Preferably, the micro group string unit 11 includes: the photovoltaic modules are connected in parallel after being connected in series.
Preferably, the three-phase full-bridge inverter circuit comprises six switching tubes, a capacitor and three inductors, wherein the switching tubes are connected in parallel with the capacitor after being connected in series in pairs, and the inductors are electrically connected to intermediate nodes of the switching tubes in series in pairs.
In the utility model, the micro-group string photovoltaic grid-connected inverter system is provided, the micro-group string units input direct current into the micro-group string grid-connected inverter through the direct current bus, the micro-group string grid-connected inverter controls the micro-group string units which are electrically connected, the input direct current is adjusted and converted into alternating current and then is combined into a power grid, and the micro-group string units form a photovoltaic array, so that the wooden barrel effect is reduced, the system cost is reduced, and meanwhile, the direct current is lower than 120V to meet the building safety voltage.
Drawings
Fig. 1 is a schematic diagram of a parallel structure of a DC/DC conversion circuit of a micro-group string photovoltaic grid-connected inverter system;
FIG. 2 is a schematic diagram of a series connection of DC/DC conversion circuits of a micro-group string photovoltaic grid-connected inverter system;
fig. 3 is a schematic structural diagram of a DC/DC conversion circuit of a micro-group string photovoltaic grid-connected inverter system according to the present utility model implemented in parallel with each other;
fig. 4 is a schematic structural diagram of a DC/DC conversion circuit of a micro-group string photovoltaic grid-connected inverter system according to the present utility model implemented in series with each other.
Detailed Description
Referring to fig. 1 and 2, the micro-group string photovoltaic grid-connected inverter system provided by the utility model comprises:
the micro-group string unit 11 is used for connecting a plurality of groups of photovoltaic modules in series and parallel to form a micro-group string array;
a direct current bus 20, configured to connect the micro-string units 11 in parallel to the micro-string grid-connected inverter 30, where the micro-string grid-connected inverter 30 includes multiple sets of DC/DC conversion circuits and DC/AC conversion circuits;
the DC/DC conversion circuit is used for controlling the micro-group string units 11 which are electrically connected, so as to realize a boosting function;
the DC/DC conversion circuit performs maximum power tracking by a hill-climbing method and a conductance increment method.
The DC/AC conversion circuit is used for converting direct current output by the DC/DC conversion circuit into alternating current and combining the alternating current with a power grid;
wherein, a plurality of groups of micro-group string units 11 are correspondingly connected in parallel with one end of a plurality of groups of DC/DC conversion circuits one by one through a DC bus 20; the multiple groups of DC/DC conversion circuits are electrically connected, and then are electrically connected through the DC/AC conversion circuits to be integrated into a power grid.
It should be further noted that, after the micro-group string unit 11 is formed by connecting 1-2 photovoltaic modules in series, 2-3 photovoltaic modules are connected in parallel, and the voltage is lower than 120V. The voltage of each photovoltaic module is lower than 60V, so that the voltage of 2 modules connected in series is 120V.
Specifically, as shown in fig. 3, the "electrical connection between the multiple DC/DC conversion circuits" is specifically: the DC/DC conversion circuits are connected in parallel, and the DC/DC conversion circuits comprise, but are not limited to, a full-bridge phase shift circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
Specifically, as shown in fig. 4, "the electrical connection between the plurality of sets of DC/DC conversion circuits" is specifically: the DC/DC conversion circuits are connected in series, and the DC/DC conversion circuits comprise, but are not limited to, a boost circuit, a buck-boost circuit, a full-bridge phase-shifting circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
Specifically, as shown in fig. 1-4, the DC/AC conversion circuit includes, but is not limited to, a three-phase full-bridge inverter circuit, a single-phase half-bridge inverter circuit, a single-phase full-bridge inverter circuit, a three-phase half-bridge inverter circuit, and a multi-level inverter.
The three-phase full-bridge inverter circuit comprises six switching tubes, a capacitor and three inductors, wherein the switching tubes are connected in parallel with the capacitor after being connected in series in pairs, and the inductors are electrically connected to intermediate nodes of the switching tubes in series in pairs.
It should be further described that one capacitor is a secondary energy storage capacitor C4, and six switching tubes G1-G6 are power MOSFET tubes or IGBT to form a three-phase grid-connected inverter full-bridge converter; three inductors L2-L4 form a three-phase grid-connected inverter filtering unit.
Specifically, as shown in fig. 3, the full-bridge phase-shifting circuit comprises a primary side H-bridge converter, a parallel resonance inductor, a full-bridge phase-shifting conversion secondary side half-bridge rectifying unit, a transformer and an input capacitor C1n; the full-bridge phase-shifting conversion circuit primary side H-bridge converter consists of switching tubes Q1n-Q4 n; l1n is a parallel resonant inductor of the full-bridge phase-shifting conversion circuit; the full-bridge phase-shifting transformation secondary side half-bridge rectifying unit consists of a diode D1n, a diode D2n, a capacitor C2n and a capacitor C3 n.
It should be further noted that the switching transistors Q1n-Q4n are power MOSFET transistors or IGBTs, and n is generally 2-10. PWM duty ratio adjustment is carried out through switching tubes Q1n-Q4n in DC/DC, input direct current is converted into high-frequency alternating current, the high-frequency alternating current is converted into high-voltage alternating current through an inductor L1n and a transformer, and then the high-voltage alternating current is rectified into direct current through a full-bridge phase-shifting conversion secondary side half-bridge rectifying unit consisting of a diode D1n, a diode D2n, a capacitor C2n and a capacitor C3n, so that a boosting function is realized.
Specifically, the diode D1n and the diode D2n are connected in parallel with the capacitor C2n and the capacitor C3n which are connected in series, and are electrically connected with the three-phase full-bridge inverter circuit after being connected in series through the capacitor C2n and the capacitor C3n to form the micro-group series grid-connected inverter 30.
Specifically, as shown in fig. 4, the boost circuit includes an input capacitor C1m, an inductor L1m, a switching tube Q2m, and an output capacitor C2m, where the input capacitor C1m and the inductor L1m are connected in series and then connected in parallel with the switching tube Q1m, and the switching tube Q2m and the output capacitor C2m are connected in series and then connected in parallel with the switching tube Q1 m.
In particular, m is generally 2 to 10; the micro-group string grid-connected inverter 30 is formed by electrically connecting one end of the capacitor C21 and one end yu1 of the capacitor C2m through the three-phase full-bridge inverter circuit.
Further, the maximum power tracking control is performed by controlling the duty ratio of the switching transistor Q1m and adjusting the voltage of the micro-group string unit 11.
PWM control is carried out on a Boost circuit switching tube Q1m, when the switching tube Q1m is turned on, the switching tube Q2m is turned off, an inductor L1m stores energy, the current flows from left to right, and the voltage at two ends of the inductor is input voltage;
when the switching tube Q1m is turned off, the inductor L1m is charged, and the Lenz theorem indicates that the current of the inductor is not immediately reduced to 0, the direction of the current is still from left to right, the switching tube Q2m is conducted, and the conduction voltage drop exists after the conduction. The electric energy of the inductor L1m and the electric energy of the input capacitor C1m are fed into the output capacitor C2m at the same time, so that a boosting function is realized.
Specifically, as shown in fig. 1 and 2, the micro group string unit 11 includes: the photovoltaic modules are connected in parallel after being connected in series.
In the specific working process of the micro-string photovoltaic grid-connected inverter system of the embodiment, the micro-string unit 11 inputs direct current into the micro-string grid-connected inverter 30 through the direct current bus 20, the micro-string grid-connected inverter 30 controls the micro-string unit 11 which is electrically connected, and the input direct current is adjusted and converted into alternating current and then is combined into a power grid.
The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art, who is within the scope of the present utility model, should make equivalent substitutions or modifications according to the technical scheme of the present utility model and the inventive concept thereof, and should be covered by the scope of the present utility model.
Claims (8)
1. A micro-grid-connected photovoltaic inverter system, comprising:
the micro-group string unit 11 is used for connecting a plurality of groups of photovoltaic modules in series and parallel to form a micro-group string array;
a direct current bus 20, configured to connect the micro-string units 11 in parallel to the micro-string grid-connected inverter 30, where the micro-string grid-connected inverter 30 includes multiple sets of DC/DC conversion circuits and DC/AC conversion circuits;
the DC/DC conversion circuit is used for controlling the micro-group string units 11 which are electrically connected, so as to realize a boosting function;
the DC/AC conversion circuit is used for converting direct current output by the DC/DC conversion circuit into alternating current and combining the alternating current with a power grid;
wherein, a plurality of groups of micro-group string units 11 are correspondingly connected in parallel with one end of a plurality of groups of DC/DC conversion circuits one by one through a DC bus 20; the multiple groups of DC/DC conversion circuits are electrically connected, and then are electrically connected through the DC/AC conversion circuits to be integrated into a power grid.
2. The micro-string photovoltaic grid-connected inverter system of claim 1, wherein the electrical connection between the plurality of sets of DC/DC conversion circuits is specifically: the DC/DC conversion circuits are connected in parallel, and include, but are not limited to, a full-bridge phase-shifting circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
3. The micro-string photovoltaic grid-connected inverter system of claim 1, wherein the electrical connection between the plurality of sets of DC/DC conversion circuits is specifically: the DC/DC conversion circuits are connected in series, and the DC/DC conversion circuits comprise, but are not limited to, a boost circuit, a buck-boost circuit, a full-bridge phase-shifting circuit, a forward circuit, a flyback circuit, an LLC circuit, a push-pull circuit, a half-bridge circuit and a full-bridge circuit.
4. The micro-string photovoltaic grid-tie inverter system of claim 1, wherein the DC/AC conversion circuit comprises, but is not limited to, a three-phase full-bridge inverter circuit, a single-phase half-bridge inverter circuit, a single-phase full-bridge inverter circuit, a three-phase half-bridge inverter circuit, a multi-level inverter.
5. The micro-grid-connected photovoltaic inverter system of claim 2, wherein the full-bridge phase-shifting circuit comprises a primary-side H-bridge converter, a parallel resonant inductor, a full-bridge phase-shifting conversion secondary-side half-bridge rectifying unit, a transformer and an input capacitor C1n; the full-bridge phase-shifting conversion circuit primary side H-bridge converter consists of switching tubes Q1n-Q4 n; l1n is a parallel resonant inductor of the full-bridge phase-shifting conversion circuit; the full-bridge phase-shifting transformation secondary side half-bridge rectifying unit consists of a diode D1n, a diode D2n, a capacitor C2n and a capacitor C3 n.
6. The micro-grid-connected photovoltaic inverter system according to claim 3, wherein the boost circuit comprises an input capacitor C1m, an inductor L1m, a switching tube Q2m and an output capacitor C2m, wherein the input capacitor C1m and the inductor L1m are connected in series and then connected in parallel with the switching tube Q1m, and the switching tube Q2m and the output capacitor C2m are connected in series and then connected in parallel with the switching tube Q1 m.
7. The micro-string photovoltaic grid-tie inverter system of claim 1, wherein the micro-string unit 11 comprises: the photovoltaic modules are connected in parallel after being connected in series.
8. The micro-grid-connected photovoltaic inverter system of claim 4, wherein the three-phase full-bridge inverter circuit comprises six switching tubes, a capacitor and three inductors, the switching tubes are connected in parallel with the capacitor after being connected in series in pairs, and the inductors are electrically connected to intermediate nodes of the switching tubes in series in pairs.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202321399504.6U CN220254149U (en) | 2023-06-05 | 2023-06-05 | Micro-group string photovoltaic grid-connected inversion system |
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| CN202321399504.6U CN220254149U (en) | 2023-06-05 | 2023-06-05 | Micro-group string photovoltaic grid-connected inversion system |
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