Photovoltaic grid-connected and off-grid hybrid inverter and photovoltaic power generation system

Abstract

The invention discloses a photovoltaic grid-connected and off-grid hybrid inverter and a photovoltaic power generation system, and belongs to the power electronic technology. The photovoltaic grid-connected and off-grid hybrid inverter comprises a direct current conversion circuit used for performing direct current conversion on electric energy from a renewable energy source assembly; the inverter circuit is used for converting the converted direct current output by the direct current conversion circuit into alternating current and outputting the alternating current to a power grid side; the direct current lightning protection circuit is used for direct current side lightning protection; the alternating current lightning protection circuit is used for alternating current side lightning protection; and the first lightning protection circuit is arranged in the direct current conversion circuit, and / or is arranged in the inverter circuit, and / or is arranged on the N line. According to the photovoltaic grid-connected and off-grid hybrid inverter, circuits in the photovoltaic grid-connected and off-grid hybrid inverter can be protected, so that the photovoltaic grid-connected and off-grid hybrid inverter can stably operate when being struck by lightning.

Description

Technical Field

[0001] The present application belongs to the field of power electronics technology, and in particular relates to a photovoltaic grid-connected and off-grid hybrid inverter and a photovoltaic power generation system. Background Art

[0002] In the related art, lightning protection circuits are added to both the AC and DC sides of photovoltaic grid-connected inverters. However, the lightning protection circuits can only discharge a portion of the lightning current. The remaining lightning current will still flow into the inverter, damaging the internal components of the inverter and failing to effectively ensure the stable operation of the inverter. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a photovoltaic on-grid and off-grid hybrid inverter and a photovoltaic power generation system.

[0004] In a first aspect, the present application provides a photovoltaic grid-connected and off-grid hybrid inverter, comprising:

[0005] A DC conversion circuit, used for converting the electric energy from the renewable energy component into DC;

[0006] An inverter circuit, used to convert the converted direct current output by the direct current conversion circuit into alternating current, and output it to the grid side;

[0007] A DC lightning protection circuit is arranged between the positive and negative output terminals of the renewable energy component, or between the positive output terminal or the negative output terminal of the renewable energy component and the PE line, and is used for DC side lightning protection;

[0008] An AC lightning protection circuit is arranged between any two three-phase AC output terminals of the inverter circuit, or between any one three-phase AC output terminal of the inverter circuit and the N line, or between any three-phase AC output terminal of the inverter circuit and the PE line, or between the N line and the PE line, for AC side lightning protection;

[0009] And a first lightning protection circuit is arranged in the DC conversion circuit, and / or, is arranged in the inverter circuit, and / or, is arranged on the N line.

[0010] In the above technical solution, a first lightning protection circuit is added on the basis of a DC lightning protection circuit and an AC lightning protection circuit to solve the lightning current flowing into the photovoltaic on-grid and off-grid hybrid inverter, thereby protecting the circuit inside the photovoltaic on-grid and off-grid hybrid inverter, so that the photovoltaic on-grid and off-grid hybrid inverter can operate stably when struck by lightning, thereby improving the reliability of the photovoltaic on-grid and off-grid hybrid inverter.

[0011] According to one embodiment of the present application, the first lightning protection circuit includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0012] In the above technical solution, when the lightning current enters the DC conversion circuit, the lightning current will flow into the first bypass unit, thereby preventing the lightning current from reversely breaking down the diode in the DC conversion circuit, thereby protecting the DC conversion circuit from damage caused by lightning and improving the reliability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0013] According to an embodiment of the present application, the first lightning protection circuit includes: a first switching device, which is connected in series or in parallel with a power switch in the DC conversion circuit.

[0014] In the above technical solution, when the lightning current enters the DC conversion circuit, it is shunted through the first switching device to reduce the current flowing through the power switch, thereby preventing the lightning current from causing overcurrent damage to the power switch in the DC conversion circuit, thereby improving the reliability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0015] According to one embodiment of the present application, the first lightning protection circuit includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0016] In the above technical solution, when the lightning current enters the DC conversion circuit, the lightning current will be directed to the second bypass unit and will not pass through the power switch in the DC conversion circuit, thereby preventing the lightning current from damaging the power switch in the DC conversion circuit and improving the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0017] According to one embodiment of the present application, the first lightning protection circuit includes at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0018] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0019] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0020] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0021] In the above technical solution, the first lightning protection circuit is arranged in the DC conversion circuit, which can be a combination of a first bypass unit, a first switching device and a second bypass unit, so as to better protect the DC conversion circuit and enhance the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0022] According to an embodiment of the present application, the first lightning protection circuit includes: a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0023] In the above technical solution, by adding a shunt unit, the overcurrent caused by lightning can be shunted to avoid overvoltage failure of the inverter unit, and the photovoltaic off-grid hybrid inverter can be effectively protected from damage caused by lightning, avoiding damage to devices in the inverter circuit.

[0024] According to an embodiment of the present application, the first lightning protection circuit further includes a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0025] In the above technical solution, the first lightning protection circuit is arranged in the DC conversion circuit and the inverter circuit, which can prevent the lightning current from damaging the devices in the DC conversion circuit and effectively protect the inverter from damage caused by lightning, so as to better protect the photovoltaic grid-connected and off-grid hybrid inverter when struck by lightning and enhance the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0026] According to one embodiment of the present application, the first lightning protection circuit includes: a second switching device connected in series on the N line, a current sampling module and a first control circuit, wherein the current sampling module is used to sample the N line current, and the first control circuit is used to control the second switching device to turn off when it is detected that the N line current exceeds a preset value.

[0027] In the above technical solution, when the lightning current enters the first lightning protection circuit, the current sampling module detects the N-line current. When it is detected that the N-line current exceeds the preset value, the first control circuit controls the second switch device to turn off, cutting off the lightning current path, thereby suppressing the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and enabling the photovoltaic grid-connected and off-grid hybrid inverter to operate stably.

[0028] According to an embodiment of the present application, the first lightning protection circuit includes: the first lightning protection circuit includes: a current suppression unit, and the current suppression unit is set at any position on the N line.

[0029] In the above technical solution, a current suppression unit is set at any position on the N line, which can suppress the lightning current from entering the photovoltaic on-grid and off-grid hybrid inverter, thereby protecting the photovoltaic on-grid and off-grid hybrid inverter and making the photovoltaic on-grid and off-grid hybrid inverter operate stably.

[0030] According to one embodiment of the present application, the first lightning protection circuit includes: a second switching device, a current sampling module and a first control circuit connected in series on the N line, and a current suppression unit; the current sampling module is used to sample the N line current, and the first control circuit is used to control the second switching device to turn off when it is detected that the N line current exceeds a preset value; the current suppression unit is set at any position on the N line.

[0031] In the above technical solution, the first lightning protection circuit is arranged on the N line, which can be a second switch device, a current sampling module and a first control circuit connected in series on the N line, a third switch device, a magnetic device, a first resistor, a drive circuit and a second control circuit, and at least two of the current suppression units, so as to suppress the lightning current from entering the inverter circuit and the DC conversion circuit, so as to better protect the DC conversion circuit and the inverter circuit and enhance the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0032] According to an embodiment of the present application, the first lightning protection circuit further includes: a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0033] In the above technical solution, the first lightning protection circuit is arranged in the inverter circuit and on the N line, which can effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to devices in the inverter circuit, and cut off the lightning current path when it is detected that the current on the N line is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0034] According to one embodiment of the present application, the first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0035] In the above technical solution, based on various implementations in which the first lightning protection circuit is set on the N line, a first bypass unit can be added, that is, the first lightning protection circuit is set in the DC conversion circuit and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0036] According to one embodiment of the present application, the first lightning protection circuit further includes:

[0037] A first switching device is connected in series or in parallel with a power switch in the DC conversion circuit.

[0038] In the above technical solution, based on the various implementations of setting the first lightning protection circuit on the N line, a first switching device can be added, that is, the first lightning protection circuit is set in the DC conversion circuit and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0039] According to one embodiment of the present application, the first lightning protection circuit also includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0040] In the above technical solution, based on various implementations of setting the first lightning protection circuit on the N line, a second bypass unit can be added, that is, the first lightning protection circuit is set in the DC conversion circuit and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0041] According to an embodiment of the present application, the first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0042] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0043] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0044] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0045] In the above technical scheme, on the basis of various implementations in which the first lightning protection circuit is set on the N line, at least two of the first bypass unit, the first switching device and the second bypass unit can be added, that is, the first lightning protection circuit is set in the DC conversion circuit and on the N line, which can better prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0046] According to one embodiment of the present application, the first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0047] In the above technical solution, on the basis of the first lightning protection circuit being arranged in the inverter circuit and on the N line, a first bypass unit can be further added, thereby realizing that the first lightning protection circuit is arranged in the DC conversion circuit, in the inverter circuit and on the N line, which can prevent the lightning current from damaging the components in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the components in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0048] According to one embodiment of the present application, the first lightning protection circuit further includes:

[0049] A first switching device is connected in series or in parallel with a power switch in the DC conversion circuit.

[0050] In the above technical solution, on the basis of the first lightning protection circuit being arranged in the inverter circuit and on the N line, a first switching device can be further added, thereby realizing that the first lightning protection circuit is arranged in the DC conversion circuit, in the inverter circuit and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the devices in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0051] According to one embodiment of the present application, the first lightning protection circuit also includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0052] In the above technical solution, on the basis of the first lightning protection circuit being arranged in the inverter circuit and on the N line, a second bypass unit can be further added, thereby realizing that the first lightning protection circuit is arranged in the DC conversion circuit 110, in the inverter circuit and on the N line, which can prevent the lightning current from damaging the components in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the components in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0053] According to an embodiment of the present application, the first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0054] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0055] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0056] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0057] In the above technical solution, on the basis that the first lightning protection circuit is arranged in the inverter circuit and on the N line, at least two of the first bypass unit, the first switching device and the second bypass unit can be added, so that the first lightning protection circuit is arranged in the DC conversion circuit, the inverter circuit and the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the devices in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0058] According to one embodiment of the present application, the photovoltaic grid-connected and off-grid hybrid inverter further includes: a fourth switching device arranged between the negative output terminal of the renewable energy component and the DC lightning protection circuit.

[0059] In the above technical solution, for the case where the photovoltaic grid-connected and off-grid hybrid inverter also includes a fourth switching device arranged between the negative output end of the renewable energy component and the DC lightning protection circuit, by adding the first lightning protection circuit in the aforementioned embodiment, it is possible to avoid damage to the devices in the DC conversion circuit caused by lightning current, and / or avoid damage to the devices in the inverter circuit, and / or, when it is detected that the N-line current is too large, the lightning current path can be cut off or the lightning current can be suppressed from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0060] In a second aspect, the present application provides a photovoltaic power generation system, comprising: a renewable energy component, an energy storage device, and a photovoltaic on-grid and off-grid hybrid inverter as described in the first aspect.

[0061] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0063] Figure 1 This is a schematic diagram of the differential mode lightning strike path from a photovoltaic panel;

[0064] Figure 2 A schematic diagram of the common-mode lightning strike path from a photovoltaic panel;

[0065] Figure 3 This is a schematic diagram of the differential mode lightning strike path from the grid-connected side;

[0066] Figure 4This is a schematic diagram of the common mode lightning strike path from the grid-connected side;

[0067] Figure 5 This is one of the schematic diagrams of the PV side lightning protection solution;

[0068] Figure 6 This is the second schematic diagram of the PV side lightning protection solution;

[0069] Figure 7 This is one of the schematic diagrams of the lightning protection scheme on the grid-connected side;

[0070] Figure 8 This is the second schematic diagram of the grid-connected side lightning protection solution;

[0071] Fig. 9 This is one of the schematic diagrams for grounding the N line;

[0072] Fig.10 This is the second schematic diagram of the N line grounding;

[0073] Fig.11 One of the schematic diagrams of lightning current in an inverter without switching devices on the PV-side;

[0074] Fig.12 The second schematic diagram of the lightning current in the inverter without switching devices on the PV-side;

[0075] Fig.13 One of the schematic diagrams of lightning current in an inverter with a switching device on the PV-side;

[0076] Fig.14 The second schematic diagram of the lightning current in the inverter with a switching device on the PV-side;

[0077] Fig.15 One of the circuit structure diagrams of the photovoltaic grid-connected and off-grid hybrid inverter provided in the embodiment of the present application;

[0078] Fig.16 This is a schematic diagram of the structure of the BOOST circuit in the embodiment of the present application;

[0079] Fig.17 The second circuit structure diagram of the photovoltaic on-grid and off-grid hybrid inverter provided in the embodiment of the present application;

[0080] Fig.18 One of the schematic diagrams of lightning strike paths for a photovoltaic on-grid and off-grid hybrid inverter provided in an embodiment of the present application;

[0081] Fig.19 A second schematic diagram of a lightning strike path for a photovoltaic on-grid and off-grid hybrid inverter provided in an embodiment of the present application;

[0082] Fig. 20A third schematic diagram of a lightning strike path for a photovoltaic on-grid and off-grid hybrid inverter provided in an embodiment of the present application;

[0083] Fig.21 A fourth schematic diagram of a lightning strike path for a photovoltaic on-grid and off-grid hybrid inverter provided in an embodiment of the present application;

[0084] Fig. 22 A fifth schematic diagram of a lightning strike path for a photovoltaic on-grid and off-grid hybrid inverter provided in an embodiment of the present application;

[0085] Fig.23 The sixth schematic diagram of the lightning strike path of the photovoltaic on-grid and off-grid hybrid inverter provided in the embodiment of the present application;

[0086] Fig.24 The seventh schematic diagram of the lightning strike path of the photovoltaic grid-connected and off-grid hybrid inverter provided in the embodiment of the present application.

[0087] Reference numerals:

[0088] 110: DC conversion circuit; 120: inverter circuit; 130: DC lightning protection circuit;

[0089] 140: AC lightning protection circuit; 150: first lightning protection circuit; 1610: inductor;

[0090] 1620: diode; 1630: power switch; 1810: first bypass unit;

[0091] 1910: first switch device; 2010: second bypass unit; 2110: shunt unit;

[0092] 2210: second switch device; 2220: current sampling module; 2230: first control circuit;

[0093] 2310: a third switch device; 2320: a magnetic device; 2330: a first resistor;

[0094] 2340: driving circuit; 2350: second control circuit; 2410: current suppression unit. DETAILED DESCRIPTION

[0095] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0096] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0097] Lightning can cause serious damage to buildings and electrical equipment. In the lightning protection design of photovoltaic inverters, choosing a reasonable design scheme, taking effective measures, and doing a good job in lightning protection design of independent photovoltaic power stations can ensure the long-term stable, safe and reliable operation of the equipment and provide users with high-quality electricity.

[0098] For photovoltaic grid-connected inverters, there are several main ways of lightning strikes:

[0099] 1) Lightning strikes from photovoltaic panels, that is, lightning strikes on the PV side (DC input side). There are two main types of lightning strikes: differential mode lightning strikes and common mode lightning strikes.

[0100] Figure 1 Figure 1 is a schematic diagram of the differential mode lightning strike path from a photovoltaic panel. Figure 1 As shown in the figure, the differential mode lightning strike path is: the lightning strike current flows into PV+ and flows out through PV-, forming a differential mode lightning strike loop.

[0101] Figure 2 Figure 1 is a schematic diagram of the common mode lightning strike path from a photovoltaic panel. Figure 2 As shown in the figure, the common mode lightning strike is between PV+ / - and PE, and the common mode lightning strike path is: the lightning strike current flows into PV+ / - and flows out through PE, forming a common mode lightning strike loop.

[0102] 2) Lightning strikes from the grid-connected side, that is, lightning strikes on the grid side (or the load connected to the grid). It is also divided into differential mode lightning strikes and common mode lightning strikes.

[0103] The differential mode lightning strike path is: lightning strikes between the phase lines of the power grid, such as lightning strikes between L1 / L2 / L3 / N. Taking the lightning strike from L1 to L2 as an example, Figure 3 is a schematic diagram of the differential mode lightning strike path from the grid-connected side, such as Figure 3 As shown, the lightning current flows in from L1 and out from L2, forming a differential mode lightning circuit.

[0104] Common mode lightning strikes between L1 / L2 / L3 / N and PE. Take L1 to PE as an example. Figure 4 is a schematic diagram of the common mode lightning strike path from the grid-connected side, such as Figure 4 As shown in FIG. 1 , the common-mode lightning strike path is: the lightning strike current flows into L1 and flows out through the internal PE, forming a common-mode lightning strike loop.

[0105] As mentioned above, the inverter is struck by lightning mainly in two directions, namely the PV side (DC output side) and the grid-connected side (AC side). Lightning strikes in both directions need to be considered when designing the inverter lightning protection solution.

[0106] Figure 5 This is one of the schematic diagrams of the PV side lightning protection solution. Figure 6 This is the second schematic diagram of the PV side lightning protection solution. For the PV side lightning protection solution, Figure 5 As shown in the figure, the solution to differential mode lightning strike is to add a lightning protection circuit between PV+ and PV-. Figure 6 As shown in the figure, the solution to common-mode lightning strikes is to add a lightning protection circuit between PV+ / - and PE. The PV-side lightning protection solution can quickly release most of the lightning current through the lightning protection circuit, but the disadvantage is that some current still flows into the inverter, which will damage the internal circuit of the inverter.

[0107] Figure 7 This is one of the schematic diagrams of the grid-connected side lightning protection scheme. Figure 8 This is the second schematic diagram of the grid-connected lightning protection solution. Figure 7 As shown in the figure, the solution to differential mode lightning strike is to add a lightning protection circuit between L1 and L2. Figure 8 As shown in the figure, the solution to common-mode lightning strikes is to add a lightning protection circuit between L1 and PE. The grid-connected lightning protection solution allows most of the lightning current to be quickly released through the lightning protection circuit. However, the disadvantage is that some current still flows into the inverter, which will damage the internal circuit of the inverter.

[0108] In addition to the scenarios analyzed above, there is another scenario, which is related to the way AC lines are connected to households. Household three-phase electricity is connected to households through a centralized substation. The centralized substation has two power transmission methods: three-phase three-wire and three-phase four-wire. The three-phase three-wire system uses a triangle connection method without an N line, and the three-phase four-wire system uses a star (Y) connection method with an N line.

[0109] If three-phase four-wire power transmission is adopted, the N line needs to be grounded to ensure safety. Therefore, there are two N line grounding methods in actual scenarios:

[0110] Fig. 9 This is one of the schematic diagrams for grounding the N line. Fig. 9 As shown, the N line is connected to the PE (ground wire) in the centralized substation, which is remote grounding. That is, for the user end, the N line is grounded over a long distance, and for the user end, the impedance of N to PE is large.

[0111] Fig.10 This is the second schematic diagram of the N line grounding. Fig.10 As shown, the N line is grounded in the household wiring cabinet, that is, the near-end grounding or the N line short-distance grounding. For the user end, N to PE is in a short-circuit state.

[0112] The above scenario where the N line is connected to the PE line near the end (i.e., the N line is short-circuited to the PE line) introduces the following lightning strike problems for different inverters:

[0113] For inverters without switching devices on the PV-side: Fig.11 , Fig.11 This is one of the schematic diagrams of lightning current in an inverter without a switching device on the PV-side. When the PV side encounters a forward lightning strike (PV+ / - to PE), the lightning current will flow from the PV side into the inverter and out from the N line to PE, causing damage to the connecting devices on the N line. Fig.12 , Fig.12 This is the second schematic diagram of the lightning current in the inverter without switching devices on the PV- side. When the PV side encounters a negative lightning strike (PE to PV+ / -), the lightning current will flow from PE into the inverter through the N line and flow out from PV+ and PV- respectively, causing damage to the connected devices on the N line.

[0114] For inverters with switching devices on the PV-side: Fig.13 , Fig.13 This is one of the schematic diagrams of lightning current in an inverter with a switch device on the PV-side. When the PV side encounters a forward lightning strike (PV+ / - to PE), the lightning current will flow from the PV side into the inverter and out from the N line to PE, causing damage to the connecting devices on the N line. Fig.14 , Fig.14 This is the second schematic diagram of the lightning current in the inverter with switching devices on the PV- side. When the PV side encounters a negative lightning strike (PE to PV+ / -), the lightning current will flow from PE through the N line into the inverter, causing damage to the connecting devices on the N line. Since the switching device on PV- is turned off, the lightning current will flow into the DC / DC circuit and then flow out from PV+, causing damage to the internal devices of the inverter.

[0115] In summary, the current inverter lightning protection scheme has the following main problems: Lightning protection circuits are added to the AC and DC sides of the photovoltaic grid-connected inverter, but the lightning protection circuit can only discharge part of the lightning current, and the remaining lightning current will still flow into the inverter, causing damage to the internal components of the inverter, and cannot effectively guarantee the stable operation of the inverter. In specific scenarios, such as the inverter in the above-mentioned proximal wiring scenario, the current existing lightning protection scheme cannot guarantee the stable operation of the inverter. For specific types of inverters, such as inverters with switching devices on the PV-line, the current existing lightning protection scheme cannot effectively guarantee the stable operation of the inverter.

[0116] In order to solve at least one of the above technical problems, the present application proposes a photovoltaic grid-connected and off-grid hybrid inverter and a photovoltaic power generation system. The photovoltaic grid-connected and off-grid hybrid inverter and the photovoltaic power generation system provided by the embodiment of the present application are described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0117] Fig.15 This is one of the circuit structure diagrams of the photovoltaic grid-connected and off-grid hybrid inverter provided in the embodiment of the present application. Fig.15 As shown, the photovoltaic grid-connected and off-grid hybrid inverter includes:

[0118] A DC conversion circuit 110, for performing DC conversion on the electric energy from the renewable energy component;

[0119] Optionally, the renewable energy component is a photovoltaic power generation component, such as a photovoltaic panel, or the renewable energy component includes a photovoltaic panel and a wind power generation component. The renewable energy component may also include other renewable energy power generation components, which is not limited in this application.

[0120] Optionally, the DC conversion circuit may also be referred to as a DC / DC circuit, including: a BOOST circuit (boost conversion circuit), a BUCK circuit (buck conversion circuit), a Buck-Boost circuit (boost-boost conversion circuit), etc. The following DC / DC circuit takes the BOOST circuit as an example, which does not constitute a limitation on the DC conversion circuit in this application.

[0121] Fig.16 : is a schematic diagram of the structure of the BOOST circuit in the embodiment of the present application, such as Fig.16 As shown, the BOOST circuit includes an inductor 1610 , a diode 1620 , and a power switch 1630 .

[0122] The inverter circuit 120 is used to convert the converted direct current output by the direct current conversion circuit into alternating current, and output it to the grid side;

[0123] Optionally, the inverter circuit can also be called a DC / AC circuit, including an inverter and a filter circuit, wherein the inverter is used to convert the converted DC voltage output by the DC conversion circuit into a three-phase sinusoidal AC power in the same phase as the grid, using the voltage and current parameters in the grid as feedback variables, and the filter circuit is used to filter the three-phase sinusoidal AC power output by the inverter and then output it to the grid.

[0124] A DC lightning protection circuit 130 is provided between the positive and negative output terminals of the renewable energy component (i.e., between PV+ and PV-), or between the positive output terminal PV+ or the negative output terminal PV- of the renewable energy component and the PE line, for DC side lightning protection;

[0125] The DC lightning protection circuit 130 is arranged between the positive and negative output terminals of the renewable energy component (i.e., between PV+ and PV-), and can process the DC side differential mode lightning current. The DC lightning protection circuit 130 is arranged between the positive output terminal PV+ or the negative output terminal PV- of the renewable energy component and the PE line, and can process the DC side common mode lightning current, so that most of the lightning current is quickly released through the DC lightning protection circuit.

[0126] The AC lightning protection circuit 140 is arranged between any two three-phase AC output terminals of the inverter circuit, or between any one three-phase AC output terminal of the inverter circuit and the N line, or between any three-phase AC output terminal of the inverter circuit and the PE line, or between the N line and the PE line, for AC side lightning protection;

[0127] The AC lightning protection circuit 140 is arranged between any two three-phase AC output terminals of the inverter circuit, such as between L1 and L2, or between any one of the three-phase AC output terminals of the inverter circuit and the N line, such as between L1 and the N line, so as to process the differential mode lightning current on the grid-connected side. The AC lightning protection circuit 140 is arranged between any three-phase AC output terminal of the inverter circuit and the PE line, such as between L1 and PE, or between the N line and the PE line, so as to process the common mode lightning current on the grid-connected side, so that most of the lightning current is quickly released through the AC lightning protection circuit.

[0128] However, the DC lightning protection circuit 130 and the AC lightning protection circuit 140 can only handle part of the lightning current, and part of the lightning current will enter the inverter. The embodiment of the present application proposes to add a first lightning protection circuit 150 to handle the lightning current flowing into the inverter.

[0129] The first lightning protection circuit 150 is disposed in the DC conversion circuit 110 and / or in the inverter circuit 120 and / or on the N line.

[0130] Fig.17 The second circuit structure diagram of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig.17 The first lightning protection circuit 150 has the following multiple implementation methods in the photovoltaic grid-connected and off-grid hybrid inverter, and can be set according to actual application scenarios and needs.

[0131] Optionally, the first lightning protection circuit 150 is disposed in the DC conversion circuit 110, and the lightning current can be discharged to the first lightning protection circuit 150, thereby preventing the lightning current from damaging the components in the DC conversion circuit.

[0132] Optionally, the first lightning protection circuit 150 is disposed in the inverter circuit 120, which can effectively protect the photovoltaic off-grid hybrid inverter from damage caused by lightning and avoid damage to components in the inverter circuit.

[0133] Optionally, the first lightning protection circuit 150 is arranged on the N line, and can cut off the lightning current path when it is detected that the current of the N line is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0134] Optionally, the first lightning protection circuit 150 includes a plurality of components, which are respectively arranged in the DC conversion circuit 110 and the inverter circuit 120, so as to prevent the lightning current from damaging the components in the DC conversion circuit and effectively protect the inverter from damage caused by lightning.

[0135] Optionally, the first lightning protection circuit 150 includes multiple components, which are respectively arranged in the DC conversion circuit 110 and on the N line to prevent lightning current from damaging devices in the DC conversion circuit. When it is detected that the current on the N line is too large, the lightning current path can be cut off to suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and ensuring the stable operation of the photovoltaic grid-connected and off-grid hybrid inverter.

[0136] Optionally, the first lightning protection circuit 150 includes multiple components, which are respectively arranged in the inverter circuit 120 and on the N line, and can effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to devices in the inverter circuit, and can cut off the lightning current path when it is detected that the current on the N line is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0137] Optionally, the first lightning protection circuit 150 includes a plurality of components, which are respectively arranged in the DC conversion circuit 110, the inverter circuit 120 and the N line, and can effectively protect the photovoltaic grid-connected and off-grid hybrid inverter.

[0138] The photovoltaic on-grid and off-grid hybrid inverter provided in the embodiment of the present application can protect the internal circuit of the photovoltaic on-grid and off-grid hybrid inverter by adding a first lightning protection circuit on the basis of the DC lightning protection circuit and the AC lightning protection circuit to solve the lightning current flowing into the photovoltaic on-grid and off-grid hybrid inverter, so that the photovoltaic on-grid and off-grid hybrid inverter can operate stably when struck by lightning, thereby improving the reliability of the photovoltaic on-grid and off-grid hybrid inverter.

[0139] In some embodiments, the first lightning protection circuit includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0140] A unidirectional conductive device can prevent current from flowing in the reverse direction. The unidirectional conductive device may be a diode, or other electronic devices capable of unidirectional conductive conduction, such as a thyristor, an optoelectronic device, and the like.

[0141] Fig.18 This is one of the lightning strike path schematic diagrams of the photovoltaic grid-connected and off-grid hybrid inverter provided in the embodiment of the present application. Fig.18 The first lightning protection circuit 150 is arranged in the DC conversion circuit 110, and includes a first bypass unit 1810, the first bypass unit 1810 includes a plurality of diodes connected in series, the input end of the first bypass unit 1810 is connected to the front end of the inductor 1610 in the DC conversion circuit 110, and the output end of the first bypass unit 1810 is connected to the output end of the diode 1620 in the DC conversion circuit 110. The first bypass unit is used to bypass the branch composed of the inductor 1610 and the diode 1620 in the DC conversion circuit.

[0142] refer to Fig.18 When the lightning current enters the DC conversion circuit 110, the lightning current will flow into the first bypass unit 1810, thereby preventing the lightning current from reversely breaking through the diode 1620 in the DC conversion circuit 110, thereby protecting the DC conversion circuit from damage caused by lightning and improving the reliability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0143] In some embodiments, the first lightning protection circuit includes: a first switching device, and the first switching device is connected in series or in parallel with a power switch in the DC conversion circuit.

[0144] Fig.19 The second schematic diagram of the lightning strike path of the photovoltaic grid-connected and off-grid hybrid inverter provided in the embodiment of the present application. Fig.19 The first lightning protection circuit 150 is arranged in the DC conversion circuit 110 , and the first lightning protection circuit 150 includes a first switching device 1910 , and the first switching device 1910 is connected in series or in parallel with the power switch 1630 in the DC conversion circuit 110 .

[0145] The first switch device 1910 can be a semiconductor switch device (or called a power switch), such as an IGBT, a MOSFET, a thyristor, etc., or an optoelectronic switch, such as a phototransistor, an optocoupler, etc., or other types of switch devices.

[0146] By adding the first switching device, the number of switching devices in the DC conversion circuit is increased.

[0147] Optionally, the first switching device 1910 may include multiple types of switching devices, which are connected in series or in parallel with the power switch 1630 in the DC conversion circuit 110 .

[0148] refer to Fig.19 When the lightning current enters the DC conversion circuit 110, it is shunted through the first switch device 1910 to reduce the current flowing through the power switch 1630, thereby preventing the lightning current from causing overcurrent damage to the power switch 1630 in the DC conversion circuit 110, thereby improving the reliability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0149] In some embodiments, the first lightning protection circuit includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0150] The unidirectional conductive device may be a diode, or other electronic devices capable of unidirectional conductiveness, such as a thyristor, an optoelectronic device, and the like.

[0151] Fig. 20 The third schematic diagram of the lightning strike path of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig. 20 The first lightning protection circuit 150 is arranged in the DC conversion circuit 110, and the first lightning protection circuit 150 includes: a second bypass unit 2010, the second bypass unit 2010 includes a plurality of diodes connected in parallel, the input end of the second bypass unit 2010 is connected to the negative input end of the DC conversion circuit 110, and the output end of the second bypass unit 2010 is connected to the positive input end of the DC conversion circuit 110. The second bypass unit 2010 is used to bypass the power switch in the DC conversion circuit, so as to protect the power switch in the DC conversion circuit from being damaged by lightning.

[0152] refer to Fig. 20 When the lightning current enters the DC conversion circuit 110, the lightning current will be led to the second bypass unit 2010 and will not pass through the power switch 1630 in the DC conversion circuit 110, thereby preventing the lightning current from damaging the power switch 1630 in the DC conversion circuit 110 and improving the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0153] In some embodiments, the first lightning protection circuit includes at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0154] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0155] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0156] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0157] It can be understood that the first lightning protection circuit 150 is arranged in the DC conversion circuit 110, and can be a combination of the above-mentioned first bypass unit 1810, the first switching device 1910 and the second bypass unit 2010, so as to better protect the DC conversion circuit and enhance the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0158] In some embodiments, the first lightning protection circuit includes: a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0159] Optionally, the shunt unit includes at least one circuit for shunt, and the shunt unit may include multiple types of circuits for shunt.

[0160] Optionally, the circuit used for current shunting can also be used for filtering, voltage division, etc.

[0161] Optionally, the circuit for shunting can be a circuit composed of at least one capacitor in parallel, an LC filter circuit, an RC filter, a switched capacitor filter, a filter constructed using active devices (such as an operational amplifier), etc.

[0162] Optionally, the shunt unit includes one or more capacitors connected in parallel, and the shunt unit is connected in parallel with the capacitor in the inverter circuit. Fig.21 The fourth schematic diagram of the lightning strike path of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig.21 The first lightning protection circuit 150 is arranged in the inverter circuit 120, and the inverter circuit is protected by increasing the number of inverter capacitors, that is, the first lightning protection circuit 150 includes a shunt unit 2110, the shunt unit includes a plurality of capacitors connected in parallel, and the shunt unit 2110 is connected in parallel with the capacitors in the inverter circuit.

[0163] refer to Fig.21In the case of differential mode lightning strike (such as AN lightning strike), by adding a shunt unit, the overcurrent caused by lightning can be shunted to avoid overvoltage failure of the inverter unit, which can effectively protect the photovoltaic and off-grid hybrid inverter from damage caused by lightning and avoid damage to the devices in the inverter circuit 120.

[0164] In some embodiments, the first lightning protection circuit further includes a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0165] It can be understood that, based on the various implementations of the aforementioned first lightning protection circuit 150 being set in the DC conversion circuit 110, the first lightning protection circuit 150 also includes a shunt unit, thereby realizing that the first lightning protection circuit 150 is set in the DC conversion circuit 110 and the inverter circuit 120, which can avoid the lightning current from damaging the devices in the DC conversion circuit and effectively protect the inverter from damage caused by lightning, so that the photovoltaic grid-connected and off-grid hybrid inverter can be better protected when struck by lightning, thereby improving the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0166] In some embodiments, the first lightning protection circuit includes: a second switch device connected in series on the N line, a current sampling module and a first control circuit, wherein the current sampling module is used to sample the N line current, and the first control circuit is used to control the second switch device to turn off when it is detected that the N line current exceeds a preset value.

[0167] Fig. 22 The fifth schematic diagram of the lightning strike path of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig. 22 The first lightning protection circuit 150 is arranged on the N line, and the first lightning protection circuit 150 includes: a second switch device 2210 connected in series on the N line, a current sampling module 2220 and a first control circuit 2230, wherein the current sampling module 2220 is used to sample the N line current, and the first control circuit is used to control the second switch device 2210 to turn off when it is detected that the N line current exceeds a preset value.

[0168] Optionally, the second switching device may be an electromagnetic relay, a DC / AC contactor, an IGBT, a MOSFET, a thyristor, a control switch or the like.

[0169] refer to Fig. 22When the lightning current enters the first lightning protection circuit 150, the current sampling module 2220 detects the N-line current. When it is detected that the N-line current exceeds the preset value, the first control circuit controls the second switch device 2210 to turn off, cutting off the lightning current path, thereby suppressing the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and enabling the photovoltaic grid-connected and off-grid hybrid inverter to operate stably.

[0170] Optionally, the current sampling module 2220 is a current sensor, or a magnetic device.

[0171] In some embodiments, the first lightning protection circuit includes: a third switching device, a magnetic device, a first resistor, a driving circuit and a second control circuit, wherein the third switching device and the magnetic device are connected in series on the N line, the first resistor is connected in parallel at both ends of the magnetic device, the magnetic device is used to detect current, and the second control circuit is used to control the third switching device to be turned off through the driving circuit when it is detected that the current flowing through the first resistor exceeds a preset value.

[0172] This embodiment provides another implementation method of the first lightning protection circuit arranged on the N line. Fig.23 The sixth schematic diagram of the lightning strike path of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig.23 The first lightning protection circuit 150 is arranged on the N line, and the first lightning protection circuit 150 includes: a third switch device 2310, a magnetic device 2320, a first resistor 2330, a drive circuit 2340 and a second control circuit 2350, wherein the third switch device 2310 and the magnetic device 2320 are connected in series on the N line, the first resistor 2330 is connected in parallel at both ends of the magnetic device 2320, and the second control circuit 2350 is used to control the third switch device 2310 to be turned off through the drive circuit 2340 when it is detected that the current flowing through the first resistor 2330 exceeds a preset value.

[0173] Optionally, the third switching device 2310 includes one of the following: an electromagnetic relay, a DC / AC contactor, an IGBT, a MOSFET, a thyristor, or a control switch.

[0174] Optionally, the magnetic device 2320 includes one of the following: a magnetic saturation transformer, a CT transformer, and a Hall sensor.

[0175] refer to Fig.23When the lightning current enters the first lightning protection circuit 150, if it is detected that the current flowing through the first resistor 2330 exceeds the preset value, the third switch device 2310 is controlled to be turned off through the driving circuit 2340, thereby cutting off the lightning current path, and suppressing the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0176] In some embodiments, the first lightning protection circuit includes: a current suppression unit, and the current suppression unit is set at any position on the N line.

[0177] The current suppression unit includes an inductor, a gas discharge tube, a semiconductor thyristor, a combination of an inductor and a capacitor, etc., and is used to suppress lightning current.

[0178] Optionally, the current suppression unit includes at least one inductor connected in series. This embodiment provides another implementation of the first lightning protection circuit arranged on the N line, Fig.24 The seventh schematic diagram of the lightning strike path of the photovoltaic off-grid hybrid inverter provided in the embodiment of the present application is shown in FIG. Fig.24 The first lightning protection circuit 150 includes: a current suppression unit 2410, which includes at least one inductor connected in series. It should be noted that the at least one inductor can be set at any position on the N line. Through the action of the inductor, a large impedance is generated for the surge current generated by the lightning strike, thereby suppressing the lightning strike current from entering the photovoltaic grid-connected and off-grid hybrid inverter, protecting the photovoltaic grid-connected and off-grid hybrid inverter, and making the photovoltaic grid-connected and off-grid hybrid inverter run stably.

[0179] A current suppression unit is set at any position on the N line to suppress the lightning current from entering the photovoltaic on-grid and off-grid hybrid inverter, thereby protecting the photovoltaic on-grid and off-grid hybrid inverter and making the photovoltaic on-grid and off-grid hybrid inverter operate stably.

[0180] In some embodiments, the first lightning protection circuit includes: a second switch device, a current sampling module and a first control circuit connected in series on the N line, and a current suppression unit;

[0181] The current sampling module is used to sample the N-line current, and the first control circuit is used to control the second switch device to turn off when it is detected that the N-line current exceeds a preset value;

[0182] The current suppression unit is arranged at any position on the N line.

[0183] It can be understood that the first lightning protection circuit 150 is set on the N line, which can be the second switching device, the current sampling module and the first control circuit, and the current suppression unit connected in series on the above-mentioned N line, so as to suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby better protecting the DC conversion circuit and the inverter circuit inside the photovoltaic grid-connected and off-grid hybrid inverter, and improving the lightning protection capability of the photovoltaic grid-connected and off-grid hybrid inverter.

[0184] In some embodiments, based on various implementations in which the first lightning protection circuit 150 is set on the N line, the first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0185] It can be understood that, based on the various implementations in which the first lightning protection circuit 150 is set on the N line, a first bypass unit can be added, that is, the first lightning protection circuit 150 is set in the DC conversion circuit 110 and on the N line, which can prevent the lightning current from damaging the components in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0186] In some embodiments, the first lightning protection circuit further includes:

[0187] A first switching device is connected in series or in parallel with a power switch in the DC conversion circuit.

[0188] It can be understood that, based on the various implementations in which the first lightning protection circuit 150 is set on the N line, a first switching device can be added, that is, the first lightning protection circuit 150 is set in the DC conversion circuit 110 and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0189] In some embodiments, the first lightning protection circuit further includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0190] It can be understood that, based on the various implementations in which the first lightning protection circuit 150 is set on the N line, a second bypass unit can be added, that is, the first lightning protection circuit 150 is set in the DC conversion circuit 110 and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0191] In some embodiments, the first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0192] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0193] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0194] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0195] It can be understood that, based on the various implementations of setting the first lightning protection circuit 150 on the N line, at least two of the first bypass unit, the first switching device and the second bypass unit can be added, that is, the first lightning protection circuit 150 is set in the DC conversion circuit 110 and on the N line, which can better prevent the lightning current from damaging the devices in the DC conversion circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0196] In some embodiments, the first lightning protection circuit further includes:

[0197] A shunt unit, the shunt unit includes at least one circuit for shunting, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

[0198] It can be understood that, based on the various implementations of setting the first lightning protection circuit 150 on the N line, a shunt unit can be added, that is, the first lightning protection circuit 150 is set in the inverter circuit 120 and on the N line, which can effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to devices in the inverter circuit, and cut off the lightning current path when it is detected that the current on the N line is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0199] Based on the previous embodiment, the first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

[0200] It can be understood that, based on the various implementations in which the first lightning protection circuit 150 is set in the inverter circuit 120 and on the N line, a first bypass unit can be added, so that the first lightning protection circuit 150 is set in the DC conversion circuit 110, the inverter circuit and the N line, which can prevent the lightning current from damaging the components in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the components in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0201] In some embodiments, the first lightning protection circuit further includes:

[0202] A first switching device is connected in series or in parallel with a power switch in the DC conversion circuit.

[0203] It can be understood that, based on the various implementations in which the first lightning protection circuit 150 is set in the inverter circuit 120 and on the N line, a first switching device can be added, so that the first lightning protection circuit 150 is set in the DC conversion circuit 110, the inverter circuit and the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the devices in the inverter circuit, and cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0204] In some embodiments, the first lightning protection circuit further includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0205] It can be understood that, on the basis of the first lightning protection circuit 150 being arranged in the inverter circuit 120 and on the N line, a second bypass unit can be further added, thereby realizing that the first lightning protection circuit 150 is arranged in the DC conversion circuit 110, in the inverter circuit and on the N line, which can prevent the lightning current from damaging the components in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the components in the inverter circuit, and can cut off the lightning current path when it is detected that the N line current is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0206] In some embodiments, the first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit;

[0207] The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit;

[0208] The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit;

[0209] The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

[0210] It can be understood that, on the basis of the first lightning protection circuit 150 being arranged in the inverter circuit 120 and on the N line, at least two of the first bypass unit, the first switching device and the second bypass unit can be added, so that the first lightning protection circuit 150 is arranged in the DC conversion circuit 110, in the inverter circuit and on the N line, which can prevent the lightning current from damaging the devices in the DC conversion circuit, effectively protect the photovoltaic grid-connected and off-grid hybrid inverter from damage caused by lightning, avoid damage to the devices in the inverter circuit, and cut off the lightning current path when it is detected that the current on the N line is too large, or suppress the lightning current from entering the photovoltaic grid-connected and off-grid hybrid inverter, thereby protecting the photovoltaic grid-connected and off-grid hybrid inverter and making the photovoltaic grid-connected and off-grid hybrid inverter operate stably.

[0211] In some embodiments, the photovoltaic grid-connected and off-grid hybrid inverter further includes: a fourth switch device disposed between the negative output terminal of the renewable energy component and the DC lightning protection circuit.

[0212] In the case where the photovoltaic off-grid hybrid inverter also includes a fourth switch device arranged between the negative output terminal of the renewable energy component and the DC lightning protection circuit, if the PV side encounters a positive lightning strike (PV+ / - to PE), whether the fourth switch device is closed or disconnected, the lightning current will flow from the PV side into the photovoltaic off-grid hybrid inverter, thereby causing damage to the internal circuit of the photovoltaic off-grid hybrid inverter. If the PV side encounters a negative lightning strike (PE to PV+ / -), and the fourth switch device is disconnected, the lightning current will flow from the AC side into the inverter circuit, flow through the DC conversion circuit, and damage the DC conversion circuit and the components in the inverter circuit. By adding the first lightning protection circuit in the aforementioned embodiment, it is possible to avoid the lightning current from damaging the components in the DC conversion circuit, and / or, avoid damaging the components in the inverter circuit, and / or, when the N line current is detected to be too large, the lightning current path can be cut off or the lightning current can be suppressed from entering the photovoltaic off-grid hybrid inverter, thereby protecting the photovoltaic off-grid hybrid inverter and making the photovoltaic off-grid hybrid inverter operate stably.

[0213] An embodiment of the present application also provides a photovoltaic power generation system, including a renewable energy component, an energy storage device, and a photovoltaic grid-connected and off-grid hybrid inverter as described in the above embodiments. For the understanding of the photovoltaic grid-connected and off-grid hybrid inverter in the photovoltaic power generation system provided in the embodiment of the present application, reference can be made to the description in the above embodiments, which will not be repeated here.

[0214] The photovoltaic on-grid and off-grid hybrid inverter in the photovoltaic power generation system provided in the embodiment of the present application is the photovoltaic on-grid and off-grid hybrid inverter in the aforementioned embodiments. When struck by lightning, the photovoltaic on-grid and off-grid hybrid inverter can operate stably, thereby improving the safety and reliability of the photovoltaic power generation system.

[0215] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0216] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a computer software product, which is stored in a storage medium (such as ROM / RAM, a disk, or an optical disk), and includes a number of instructions for a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present application.

[0217] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

[0218] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0219] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A photovoltaic on-grid and off-grid hybrid inverter, characterized in that: include: A DC conversion circuit, used for converting the electric energy from the renewable energy component into DC; An inverter circuit, used to convert the converted direct current output by the direct current conversion circuit into alternating current, and output it to the grid side; A DC lightning protection circuit is arranged between the positive and negative output terminals of the renewable energy component, or between the positive output terminal or the negative output terminal of the renewable energy component and the PE line, and is used for DC side lightning protection; An AC lightning protection circuit is arranged between any two three-phase AC output terminals of the inverter circuit, or between any one three-phase AC output terminal of the inverter circuit and the N line, or between any three-phase AC output terminal of the inverter circuit and the PE line, or between the N line and the PE line, for AC side lightning protection; And a first lightning protection circuit is arranged in the DC conversion circuit, and / or, is arranged in the inverter circuit, and / or, is arranged on the N line.

2. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

3. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a first switch device, which is connected in series or in parallel with a power switch in the DC conversion circuit.

4. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

5. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes at least two of a first bypass unit, a first switch device and a second bypass unit; The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit; The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit; The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

6. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

7. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 2 to 5, characterized in that: The first lightning protection circuit further includes a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

8. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a second switch device connected in series on the N line, a current sampling module and a first control circuit, wherein the current sampling module is used to sample the N line current, and the first control circuit is used to control the second switch device to turn off when it is detected that the N line current exceeds a preset value.

9. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit includes: a current suppression unit, and the current suppression unit is arranged at any position on the N line.

10. The photovoltaic on-grid and off-grid hybrid inverter according to claim 1, characterized in that: The first lightning protection circuit comprises: a second switch device, a current sampling module and a first control circuit connected in series on the N line, and a current suppression unit; The current sampling module is used to sample the N-line current, and the first control circuit is used to control the second switch device to turn off when it is detected that the N-line current exceeds a preset value; The current suppression unit is arranged at any position on the N line.

11. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 8 to 10, characterized in that: The first lightning protection circuit further includes: a shunt unit, the shunt unit includes at least one circuit for shunt, and the shunt unit is connected in parallel with the inverter unit of the inverter circuit.

12. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 8 to 10, characterized in that: The first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

13. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 8 to 10, characterized in that: The first lightning protection circuit also includes: a first switch device, which is connected in series or in parallel with the power switch in the DC conversion circuit.

14. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 8 to 10, characterized in that: The first lightning protection circuit also includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

15. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 8 to 10, characterized in that: The first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit; The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit; The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit; The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

16. The photovoltaic on-grid and off-grid hybrid inverter according to claim 11, characterized in that: The first lightning protection circuit also includes: a first bypass unit, the first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit.

17. The photovoltaic on-grid and off-grid hybrid inverter according to claim 11, characterized in that: The first lightning protection circuit also includes: a first switch device, which is connected in series or in parallel with the power switch in the DC conversion circuit.

18. The photovoltaic on-grid and off-grid hybrid inverter according to claim 11, characterized in that: The first lightning protection circuit also includes: a second bypass unit, the second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

19. The photovoltaic on-grid and off-grid hybrid inverter according to claim 11, characterized in that: The first lightning protection circuit further includes: at least two of a first bypass unit, a first switch device, and a second bypass unit; The first bypass unit includes at least one unidirectional conductive device, the input end of the first bypass unit is connected to the positive input end of the DC conversion circuit, and the output end of the first bypass unit is connected to the positive output end of the DC conversion circuit; The first switch device is connected in series or in parallel with the power switch in the DC conversion circuit; The second bypass unit includes at least one unidirectional conductive device, the input end of the second bypass unit is connected to the negative input end of the DC conversion circuit, and the output end of the second bypass unit is connected to the positive input end of the DC conversion circuit.

20. The photovoltaic on-grid and off-grid hybrid inverter according to any one of claims 1-6, 8-10, 16-19, characterized in that: The photovoltaic on-grid and off-grid hybrid inverter further includes: a fourth switch device arranged between the negative output terminal of the renewable energy component and the DC lightning protection circuit.

21. A photovoltaic power generation system, characterized in that: The invention comprises a renewable energy component, an energy storage device and a photovoltaic on-grid and off-grid hybrid inverter as claimed in any one of claims 1 to 20.

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