Photovoltaic (PV) side lightning protection device of string type photovoltaic inverter

Abstract

The utility model discloses a string photovoltaic inverter PV side lightning protection device which comprises a lightning protection module and an inverter built-in DSP module, the lightning protection module comprises a housing, and a piezoresistor MOV, a fuse wire theta and a spring holding unit which are installed in the housing, one end of the piezoresistor MOV is used as a lightning protection pin 2, and the other end of the piezoresistor MOV is used as a lightning protection pin 3. The other end is electrically connected with one end of the fuse wire theta; the other end of the fuse wire theta is used as a lightning protection pin I; the spring holding unit is provided with a third remote signaling pin and a fourth remote signaling pin, and the spring holding unit is used for disconnecting the third remote signaling pin and the fourth remote signaling pin when the MOV is in an open circuit. A first lightning protection pin and a second lightning protection pin of the lightning protection module are used for being electrically connected with the PV module, a third remote signaling pin and a fourth remote signaling pin of the lightning protection module are used for being grounded, the other one is electrically connected with a power source Vcc, and the inverter built-in DSP module is electrically connected between the power source Vcc and the lightning protection module. The lightning protection circuit has the effect of timely detecting the damage of the lightning protection circuit.

Description

Technical Field

[0001] The present application relates to the field of photovoltaics, and in particular to a lightning protection device for a PV side of a string-type photovoltaic inverter. Background Art

[0002] The photovoltaic system is mainly composed of solar panels and photovoltaic inverters. Photovoltaic panels are placed on the roof all year round and are inevitably subject to thunderstorms. In order to protect the photovoltaic inverter and reduce the losses caused by lightning strikes, the inverter needs to be installed with a PV lightning protection module.

[0003] In the market, MOV (varistor) is basically used for PV (solar cell) side lightning protection. This method has a relatively low cost, but when MOV or gas discharge tube is damaged by lightning, the inverter cannot detect that the lightning protection circuit has been damaged, and the owner cannot replace the damaged components in time. When lightning strikes again, the inverter is likely to be damaged by lightning, causing great economic losses to the owner. Utility Model Content

[0004] In order to timely detect damage to the lightning protection circuit, protect the inverter of the photovoltaic system, and reduce economic losses, the present application provides a PV side lightning protection device for a string photovoltaic inverter.

[0005] The present application provides a PV side lightning protection device for a string photovoltaic inverter, which adopts the following technical solution:

[0006] A lightning protection device for a string photovoltaic inverter PV side, comprising a lightning protection module and an inverter built-in DSP module, wherein the lightning protection module comprises a housing and a varistor MOV, a fuse θ and a spring holding unit installed in the housing, wherein one end of the varistor MOV serves as a lightning protection pin 2, and the other end is electrically connected to one end of the fuse θ; the other end of the fuse θ serves as a lightning protection pin 1; the spring holding unit has a remote signal pin 3 and a remote signal pin 4, and the spring holding unit is used to fail when the varistor MOV is open-circuited, and disconnect the remote signal pin 3 and the remote signal pin 4;

[0007] The lightning protection pin 1 and the lightning protection pin 2 of the lightning protection module are used to electrically connect the PV module, the remote signal pin 3 and the remote signal pin 4 of the lightning protection module are used to connect one to ground and the other to the power supply Vcc, and the built-in DSP module of the inverter is electrically connected between the power supply Vcc and the lightning protection module.

[0008] Optionally, a pull-up resistor R is further included, wherein the pull-up resistor R is connected in series between the lightning protection module and the power supply Vcc, and the inverter built-in DSP module is electrically connected between the pull-up resistor R and the lightning protection module.

[0009] Optionally, there are multiple lightning protection modules, and the positive electrode of one PV module matches one lightning protection module and is electrically connected to lightning protection pin one;

[0010] The negative poles of the plurality of PV modules are electrically connected to the lightning protection pin 1 of the same lightning protection module, and this lightning protection module is referred to as lightning protection module 1;

[0011] One of the lightning protection modules is called lightning protection module N, the lightning protection pin 2 of lightning protection module 1 is electrically connected to the lightning protection pin 1 of lightning protection pin N, and the lightning protection pin 2 of lightning protection module N is connected to the earth PE;

[0012] The other multiple lightning protection modules connected to the positive pole of the PV module are connected in series through the remote signal pins three and four, one end of which is connected to the built-in DSP module of the inverter and the other end is connected to the remote signal pin four of the lightning protection module N; the remote signal pin three of the lightning protection module N is connected to GND.

[0013] Optionally, a voltage-stabilizing capacitor is further included, one end of the voltage-stabilizing capacitor is connected to the positive electrode of the PV module, and the other end of the voltage-stabilizing capacitor is connected to the negative electrode of the PV module.

[0014] Optionally, a filter capacitor combination is further included, wherein the filter capacitor combination includes two sub-capacitors connected in series, the filter capacitor is connected in parallel with the voltage stabilizing capacitor, and the connection point of the two sub-capacitors is connected to the ground PE.

[0015] Optionally, a signal indicating unit is installed on the housing, and the signal indicating unit is electrically connected to the varistor MOV and the fuse θ.

[0016] In summary, the present application includes at least one of the following beneficial technical effects: when the fuse θ between pin 1 and pin 2 fails due to abnormal temperature exceeding the limit caused by lightning strike, the fuse θ will be disconnected first, so that the failure mode of the varistor MOV presents an open circuit failure, and the spring holding unit will cause the remote signal pin 3 and the remote signal pin 4 to be disconnected; the remote signal pin 3 and the remote signal pin 4 are both low-voltage safety sides, and the remote signal pin 3 is connected to the internal GND of the photovoltaic system, and the remote signal pin 4 is sent to the built-in DSP module of the inverter through the power supply, so that the damage of the lightning protection circuit can be detected in time, the inverter of the photovoltaic system can be protected, and economic losses can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the electrical schematic diagram of the lightning protection module of the present application;

[0018] Figure 2 It is a schematic diagram of the overall structure of this application;

[0019] Figure 3 It is a schematic diagram of the circuit structure when multiple lightning protection modules of the present application are used in conjunction with each other. DETAILED DESCRIPTION

[0020] The following is combined with Figure 1-3 This application is described in further detail.

[0021] The embodiment of the present application discloses a lightning protection device for a PV side of a string-type photovoltaic inverter.

[0022] Reference Figure 1-3 The PV side lightning protection device of the string photovoltaic inverter includes a lightning protection module and an inverter built-in DSP module, which is designed to detect the inverter in time after the MOV or gas discharge tube is damaged by lightning, so as to protect the inverter of the photovoltaic system and reduce economic losses.

[0023] The lightning protection module includes a shell and a varistor MOV, a fuse θ and a spring holding unit installed in the shell, wherein one end of the varistor MOV serves as a lightning protection pin two (i.e., P2 in the figure), and the other end is electrically connected to one end of the fuse θ; the other end of the fuse θ serves as a lightning protection pin one (i.e., P1 in the figure); the spring holding unit has a remote signal pin three (i.e., P3 in the figure) and a remote signal pin four (i.e., P4 in the figure), and the spring holding unit is used to fail when the varistor MOV is open-circuited, and disconnect the remote signal pin three and the remote signal pin four.

[0024] In one embodiment of the present device, the spring holding unit can refer to and select the relay armature closing structure, that is, the armature posture is maintained by the electromagnet, the electromagnet is connected in series with the primary power supply, and the power supply is opened and closed, so as to realize the function of keeping closed when power is on and failing to open the circuit when power is off.

[0025] In one embodiment of the present device, lightning protection pin 1 and lightning protection pin 2 are used to electrically connect the PV module, remote signal pin 3 and remote signal pin 4 of the lightning protection module are used for one grounding and one electrically connected to the power supply Vcc (which can be 3.3V), and the built-in DSP module of the inverter is electrically connected between the power supply Vcc and the lightning protection module.

[0026] When the fuse θ between pin 1 and pin 2 fails due to abnormal temperature exceeding the limit of the varistor MOV due to lightning strike, the fuse θ will be disconnected first, so that the failure mode of the varistor MOV will be open circuit failure, and the spring holding unit will cause the remote signal pin 3 and the remote signal pin 4 to be disconnected; the remote signal pin 3 and the remote signal pin 4 are both low-voltage safety sides. The remote signal pin 3 is connected to the internal GND of the photovoltaic system, and the remote signal pin 4 is sent to the built-in DSP module of the inverter through the internal 3.3V power supply and a certain pull-up resistor R, so as to timely detect the damage of the lightning protection circuit, protect the inverter of the photovoltaic system, and reduce economic losses.

[0027] The connection method of the pull-up resistor R is specifically as follows: the pull-up resistor R is connected in series between the lightning protection module and the power supply Vcc, and the built-in DSP module of the inverter is electrically connected between the pull-up resistor R and the lightning protection module.

[0028] In actual application, a photovoltaic inverter is generally composed of multiple independent PV modules. Therefore, in an embodiment of the present device, there are multiple lightning protection modules, and the positive pole of one PV module is matched with one lightning protection module and electrically connected to the lightning protection pin one.

[0029] Assuming that there are two PV modules, called PV1 and PV2 respectively, then: the negative poles of PV1 and PV2 are electrically connected to the lightning protection pin 1 of the same lightning protection module, and this lightning protection module is called lightning protection module 1 (that is, lightning protection module 1 in the figure, Arabic numerals are used to represent Chinese in the figure).

[0030] A lightning protection module is called a lightning protection module N, the lightning protection pin 2 of the lightning protection module 1 is electrically connected to the lightning protection pin 1 of the lightning protection pin N, and the lightning protection pin 2 of the lightning protection module N is connected to the earth PE;

[0031] After the other multiple lightning protection modules connected to the positive pole of the PV module are connected in series through the remote signal pins 3 and 4, one end is connected to the built-in DSP module of the inverter, and the other end is connected to the remote signal pin 4 of the lightning protection module N; the remote signal pin 3 of the lightning protection module N is connected to GND. Among them, the other multiple lightning protection modules are connected in series through the remote signal pins 3 and 4: two remote signal pins 3 are connected, and two remote signal pins 4 are connected.

[0032] It can be understood that the above PV1 and PV2 are respectively connected between the positive and negative poles of the DC input terminal of the photovoltaic inverter.

[0033] According to the above settings, if any PV is disconnected by lightning, that is, when the fuse θ between the P1 and P2 pins of any lightning protection module is blown, the P3 and P4 pins of the corresponding lightning protection module will be disconnected, and then the signal side loop will be disconnected, and the level signal sent to the DSP will change from the normal low level to a 3.3V high level. When the DSP detects that the level signal has changed to a high level, the DSP will issue a PV lightning protection module failure and upload it to the photovoltaic inverter monitoring platform. After seeing this, the user can contact the photovoltaic inverter after-sales service for machine maintenance to ensure that any level will respond in time when it is struck by a large current lightning, and conduct the lightning current into the earth to reduce the ground potential and protect the photovoltaic inverter from being damaged by lightning.

[0034] Furthermore, the device also includes a combination of a voltage stabilizing capacitor and a filter capacitor, wherein the number of the voltage stabilizing capacitors matches the number of PV modules, one end of the voltage stabilizing capacitor is connected to the positive electrode of the PV module, and the other end is connected to the negative electrode of the PV module. The filter capacitor combination includes two sub-capacitors connected in series, the filter capacitor and the voltage stabilizing capacitor are connected in parallel, and the connection point of the two sub-capacitors is connected to the earth PE.

[0035] Taking the figure as an example, the voltage stabilizing capacitors are C1 and C4; the sub-capacitors of the filter capacitor are C2, C3, C5 and C6.

[0036] The above settings can be used to improve circuit stability and reduce interference.

[0037] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A PV side lightning protection device for a string photovoltaic inverter, characterized in that: It includes a lightning protection module and an inverter built-in DSP module, the lightning protection module includes a shell and a varistor MOV, a fuse θ and a spring holding unit installed in the shell, one end of the varistor MOV is used as a lightning protection pin 2, and the other end is electrically connected to one end of the fuse θ; the other end of the fuse θ is used as a lightning protection pin 1; the spring holding unit has a remote signal pin 3 and a remote signal pin 4, and the spring holding unit is used to fail when the varistor MOV is open-circuited, disconnecting the remote signal pin 3 and the remote signal pin 4; The lightning protection pin 1 and the lightning protection pin 2 of the lightning protection module are used to electrically connect the PV module, the remote signal pin 3 and the remote signal pin 4 of the lightning protection module are used to connect one to ground and the other to the power supply Vcc, and the built-in DSP module of the inverter is electrically connected between the power supply Vcc and the lightning protection module.

2. The PV side lightning protection device of a string photovoltaic inverter according to claim 1, characterized in that: It also includes a pull-up resistor R, which is connected in series between the lightning protection module and the power supply Vcc, and the inverter built-in DSP module is electrically connected between the pull-up resistor R and the lightning protection module.

3. The PV side lightning protection device of a string photovoltaic inverter according to claim 1, characterized in that: There are multiple lightning protection modules, and the positive electrode of one PV module matches one lightning protection module and is electrically connected to lightning protection pin one; The negative poles of the plurality of PV modules are electrically connected to the lightning protection pin 1 of the same lightning protection module, and this lightning protection module is referred to as lightning protection module 1; One of the lightning protection modules is called lightning protection module N, the lightning protection pin 2 of lightning protection module 1 is electrically connected to the lightning protection pin 1 of lightning protection pin N, and the lightning protection pin 2 of lightning protection module N is connected to the earth PE; The other multiple lightning protection modules connected to the positive pole of the PV module are connected in series through the remote signal pins three and four, one end of which is connected to the built-in DSP module of the inverter and the other end is connected to the remote signal pin four of the lightning protection module N; the remote signal pin three of the lightning protection module N is connected to GND.

4. The PV side lightning protection device of a string photovoltaic inverter according to claim 3, characterized in that: It also includes a voltage-stabilizing capacitor, one end of which is connected to the positive electrode of the PV module, and the other end of which is connected to the negative electrode of the PV module.

5. The PV side lightning protection device of a string photovoltaic inverter according to claim 4, characterized in that: It also includes a filter capacitor combination, which includes two sub-capacitors connected in series. The filter capacitor is connected in parallel with the voltage stabilizing capacitor, and the connection point of the two sub-capacitors is connected to the ground PE.

6. The PV side lightning protection device of a string photovoltaic inverter according to claim 1, characterized in that: A signal indicating unit is installed on the housing, and the signal indicating unit is electrically connected to the varistor MOV and the fuse θ.

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