CN117907721A - Inverter detection device, control method thereof and photovoltaic inverter - Google Patents

Abstract

The application relates to the technical field of inverters, and discloses an inverter detection device, a control method thereof and a photovoltaic inverter, wherein the inverter detection device comprises the following components: the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device. According to the technical scheme provided by the application, the first resistive device and the second resistive device are arranged on any phase of live wire circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the voltage of the zero line circuit is changed, and whether the relay of the circuit is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved.

Description

Inverter detection device, control method thereof and photovoltaic inverter

Technical Field

The application relates to the technical field of inverters, in particular to an inverter detection device, a control method thereof and a photovoltaic inverter.

Background

Along with the development of new energy power generation technology, the inverter is also widely applied. The inverter is used for converting the direct current electric signal into an alternating current electric signal so as to input alternating current generated by the power generation equipment into a power grid. In order to ensure the safety of the power generation equipment, a relay needs to be arranged between the power grid and the output end of the inverter to realize electrical isolation.

Fig. 1 is a schematic diagram of a photovoltaic inverter, as shown in fig. 1, the photovoltaic inverter is connected with a power GRID through a power transmission line, three groups of relays are arranged in the photovoltaic inverter, namely an INV relay arranged on the output side of the photovoltaic inverter, an MID inverter arranged on the power transmission line of the photovoltaic inverter and a GRID relay arranged at the connection part of the power transmission line, the power GRID and a load, so that the connection between the inverter, the power GRID and the load is timely cut off when the power transmission line breaks down, and the safety of power generation equipment and load equipment is ensured. However, in the working process, the situation that the power generation equipment cannot be disconnected with the power grid in time due to adhesion of the relay may exist, so that economic loss is caused. Therefore, the working state of the relay needs to be detected in time so as to ensure that the relay works normally. At present, voltage sampling points are usually arranged at two ends of each relay to collect voltages at two ends of the relay, whether the relay is adhered or not is judged by judging the difference value of the two ends of the relay after a turn-off instruction is sent to the relay, but the mode is too dependent on the voltages collected by the sensor, and when a target point circuit is not in a grid-connected state or the target relay is an N-line relay, whether the relay is normally turned off or not cannot be judged normally. When the voltage detection equipment fails, maintenance personnel cannot find the voltage detection equipment in time, so that the equipment safety is reduced.

It can be seen that how to provide a safer and more reliable inverter detection device with low cost is a problem to be solved by the skilled person.

Disclosure of Invention

The application aims to solve the problems of higher cost and low reliability in the prior art when a relay is judged to be abnormal by detecting voltage difference values at two ends of an inverter, and therefore, the application provides an inverter detection device, a control method thereof and a photovoltaic inverter, so that the dependence on voltage detection values is reduced, and the accuracy of detection results is improved.

In order to solve the above technical problems, the present application provides an inverter detection device applied to a three-phase inverter circuit, the inverter detection device comprising:

the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device;

the first end of the first resistive device is connected with the first end of the target relay contact, the second end of the first resistive device and the first end of the second resistive device are connected with the second end of the target relay contact, and the second end of the second resistive device is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit;

The voltage detection circuit is connected with a zero line of the three-phase inverter circuit to obtain a voltage detection signal;

The controller is connected with the relay to be tested and the voltage detection circuit, so as to send a turn-off signal to the relay to be tested, and judge whether the relay to be tested is normally turned off or not according to the voltage detection signal.

Preferably, the relay of the three-phase inverter circuit includes: INV group relay, MID group relay, and GRID group inverter;

the first end of the INV group relay contact is connected with the output end of the inverter, and the connection point is used as a first sampling point;

The second end of the INV group relay contact is connected with the first end of the MID group relay contact, and the connection point is used as a second sampling point;

the second end of the MID group relay contact is connected with the first end of the GRID group relay contact, and the connection point is used as a third sampling point;

And the second end of the GRID group relay contact is connected with a power GRID, and the connection point is used as a fourth sampling point.

Preferably, the MID group relay shares a hardware drive, and the relay provided on the hot line of the three-phase inverter circuit in the GRID group relay shares a hardware drive.

Preferably, the controller is further configured to obtain a voltage difference value between two ends of the relay to be tested of the GRID group relay, so as to determine whether the relay to be tested is normally turned off.

Preferably, the power supply further comprises a first capacitor, a second capacitor and a third capacitor to inhibit electromagnetic interference of the power supply;

The first end of the first capacitor is connected with an R-phase circuit of the three-phase inverter circuit, and the second end of the first capacitor is connected with an N-line circuit of the three-phase inverter circuit;

the first end of the second capacitor is connected with an S-phase circuit of the three-phase inverter circuit, and the second end of the second capacitor is connected with an N-line circuit of the three-phase inverter circuit;

the first end of the third capacitor is connected with the T-phase circuit of the three-phase inverter circuit, and the second end of the third capacitor is connected with the N-line circuit of the three-phase inverter circuit.

In order to solve the technical problem, the application also provides a control method of the inverter detection device, which is applied to the inverter detection device comprising a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first end of the first resistive device is connected with the first end of the target relay contact, the second end of the first resistive device and the first end of the second resistive device are connected with the second end of the target relay contact, and the second end of the second resistive device is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit; the voltage detection circuit is connected with a zero line of the three-phase inverter circuit; the inverter detection device control method comprises the following steps:

The method comprises the steps of controlling a relay to be tested to be turned off, and obtaining voltage detection signals at two ends of the relay to be tested;

And judging whether the relay to be tested is normally turned off or not according to the voltage detection signal.

Preferably, the determining whether the relay to be tested is normally turned off according to the voltage detection signal includes:

acquiring a first voltage value of a connection point of the first resistive device and the second resistive device and a second voltage value of the relay to be tested;

acquiring a first sampling voltage difference value of a third sampling point and a fourth sampling point in a zero line of the three-phase inverter circuit, and judging whether the first sampling voltage difference value is equal to a difference value between the first voltage value and the second voltage value;

And if so, determining that the relay to be tested is not normally turned off.

Preferably, the method further comprises:

Acquiring a second sampling voltage difference value, wherein the second sampling voltage difference value is the voltage difference value of a second sampling point and a third sampling point;

Judging whether the second sampling voltage difference value is larger than a first voltage threshold value or not;

if the voltage is not greater than the first voltage threshold, determining that the MID group relay is abnormal in turn-off;

If the alternating current effective value of the first sampling point is larger than the first voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than the second voltage threshold value and smaller than a third voltage threshold value;

If the alternating current effective value of the first sampling point is larger than a second voltage threshold and smaller than a third voltage threshold, determining that the MID group relay is normally turned off;

otherwise, determining that the MID group relay is turned off abnormally.

Preferably, the method further comprises:

acquiring a third sampling voltage difference value of the first sampling point and the second sampling point;

judging whether the third sampling voltage difference value is larger than a fourth voltage threshold value or not;

if the voltage is not greater than the fourth voltage threshold, determining that the MID group relay is abnormal in turn-off;

if the alternating current effective value of the first sampling point is larger than the fourth voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than a second threshold value and smaller than a third threshold value;

If the alternating current effective value of the first sampling point is larger than a second threshold value and smaller than a third threshold value, determining that the INV group relay is normally turned off;

otherwise, determining that the INV group relay is turned off abnormally.

In order to solve the technical problem, the application also provides a photovoltaic inverter, which comprises the inverter detection device.

The application provides an inverter detection device, which is applied to a three-phase inverter circuit, and comprises: the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first end of the first resistive device is connected with the first end of the target relay contact, the second end of the first resistive device and the first end of the second resistive device are both connected with the second end of the target relay contact, and the second end of the second resistive device is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit; the voltage detection circuit is connected with a zero line of the three-phase inverter circuit to obtain a voltage detection signal; the controller is connected with the relay to be tested and the voltage detection circuit to send a turn-off signal to the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal. Therefore, according to the technical scheme provided by the application, the first resistive device and the second resistive device are arranged on any phase of live wire circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the voltage of the zero line circuit is changed, and whether the relay of the zero line circuit is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved.

In addition, the application also provides an inverter detection device control method and a photovoltaic inverter, which correspond to the inverter detection device and have the same effects.

Drawings

For a clearer description of embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described, it being apparent that the drawings in the following description are only some embodiments of the present application, and other drawings may be obtained according to the drawings without inventive effort for those skilled in the art.

FIG. 1 is a schematic diagram of a photovoltaic inverter;

Fig. 2 is a block diagram of an inverter detecting device according to an embodiment of the present application;

Fig. 3 is a flowchart of a control method of an inverter detection device according to an embodiment of the present application;

Fig. 4 is a schematic diagram of detecting a GRID group neutral line relay according to an embodiment of the present application;

fig. 5 is a schematic diagram of another GRID group neutral line relay detection according to an embodiment of the present application;

fig. 6 is a schematic diagram of detecting a GRID group live wire relay according to an embodiment of the present application;

Fig. 7 is an equivalent circuit diagram of all conductive GRID group relays according to an embodiment of the present application;

fig. 8 is a block diagram of a sticking of a MIDR relay according to an embodiment of the application;

Fig. 9 is a block diagram of MIDN relay sticking according to an embodiment of the present application;

Fig. 10 is an equivalent circuit diagram of MIDN relay sticking according to an embodiment of the present application;

FIG. 11 is a block diagram of a MIDN and MIDR relay simultaneously stuck according to an embodiment of the present application;

Fig. 12 is an equivalent circuit diagram of a MIDN and MIDR relay simultaneously sticking together provided by an embodiment of the application;

fig. 13 is a block diagram of simultaneous sticking of a midp relay and a midp relay according to an embodiment of the present application;

Fig. 14 is an equivalent circuit diagram of simultaneous sticking of an midp relay and a midp relay provided by an embodiment of the present application;

FIG. 15 is a block diagram of a single INV bank live relay sticking according to an embodiment of the present application;

fig. 16 is an equivalent circuit diagram of a single INV group live wire relay sticking provided by the embodiment of the application;

FIG. 17 is a block diagram of a single INV group zero line relay stuck according to an embodiment of the present application;

FIG. 18 is an equivalent circuit diagram of a single INV group zero line relay stuck according to an embodiment of the present application;

Fig. 19 is a block diagram of all the adhesion of the INV group relay according to the embodiment of the present application;

fig. 20 is an equivalent circuit diagram of all the stiction of the INV group relay according to the embodiment of the present application;

fig. 21 is a block diagram of all the adhesion of the live wire relay of the INV group according to the embodiment of the present application;

fig. 22 is an equivalent circuit diagram of all the live wire relays of the INV group in a stuck state, provided by the embodiment of the application;

the reference numerals are as follows: the voltage detection circuit is characterized in that the voltage detection circuit is arranged at 1, the voltage detection circuit is arranged at 2, the first resistive device is arranged at3, the second resistive device is arranged at 4, the INV group relay is arranged at 5, the MID group relay is arranged at 6, and the GRID relay is arranged at 7.

Detailed Description

The following description of the embodiments of the present application will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present application, but not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by a person of ordinary skill in the art without making any inventive effort are within the scope of the present application.

The application provides an inverter detection device, a control method thereof and a photovoltaic inverter, so as to more accurately detect whether the zero line relay is adhered or not, thereby improving the accuracy of a detection result.

In the working process of the three-phase energy storage inverter, a relay is arranged between a three-phase circuit of a power grid and the output end of the inverter for electric isolation, and when the inverter does not work, the relay is ensured to be reliably disconnected. The detection scheme is specially designed for the method, so that the sticking fault of the relay can be accurately detected, and the safety and reliability of the inverter circuit are improved. In the application, the first resistive device and the second resistive device are arranged on any non-N-line circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the N-line voltage is changed, and whether the relay of the N-line circuit is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by the N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved.

In order to better understand the aspects of the present application, the present application will be described in further detail with reference to the accompanying drawings and detailed description.

Fig. 2 is a block diagram of an inverter detection device according to an embodiment of the present application, and as shown in fig. 2, the inverter detection device is applied to a three-phase inverter circuit, and includes: the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first end of the first resistive device is connected with the first end of the target relay contact, the second end of the first resistive device and the first end of the second resistive device are both connected with the second end of the target relay contact, and the second end of the second resistive device is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit; the voltage detection circuit is connected with the three-phase inverter circuit to acquire a voltage detection signal; the controller is connected with the relay to be tested and the voltage detection circuit to send a turn-off signal to the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal.

It should be noted that the first resistive device is connected in series with any non-N-wire relay under test, but the resistive devices introduced in each hot wire cannot be identical to ensure that a voltage disturbance is induced at the neutral wire.

In this embodiment, an inverter detection device and a work flow thereof will be described by taking a three-phase four-wire inverter circuit as an example, wherein a neutral circuit refers to an N-wire circuit of a three-phase circuit, and a live circuit refers to a non-N-wire circuit of a three-phase circuit. In normal operation, the load of each phase in the three-phase circuit is balanced, and the voltage of the N-line circuit (neutral line) is zero. In a specific implementation, the target relay is a relay in a non-N-wire circuit in a three-phase inverter circuit. When the first resistive device is connected into any phase circuit and the load variation is applied to the N-line circuit through the second resistive device, the load of the three-phase circuit is unbalanced, and a voltage difference exists in the N-line circuit. In a specific implementation, the inverter detection device may be applied to different multiphase circuits, which is not limited herein.

It will be appreciated that switching in a resistive device to any one of the phases of the three-phase circuit will result in an unbalanced load on the three-phase circuit, affecting the normal operation of the three-phase circuit. Therefore, in this embodiment, the first resistive device is connected in parallel with the target relay, and when the target relay is in the off state, the first resistive device is connected to the circuit, so as to ensure the normal operation of the three-phase circuit. It should be noted that the first resistive device and the second resistive device are both high-value resistors.

Note that the non-N-line mentioned in the present embodiment includes an R-phase circuit, an S-phase circuit, and a T-phase circuit in a three-phase circuit. As shown in fig. 2, the relay to be tested includes: INV group relay, MID group relay, and GRID group inverter; the first end of the INV group relay contact is connected with the output end of the inverter, and the connection point is used as a first sampling point; the second end of the INV group relay contact is connected with the first end of the MID group relay contact, and the connection point is used as a second sampling point; the second end of the MID group relay contact is connected with the first end of the GRID group relay contact, and the connection point is used as a third sampling point; and a second end of the GRID group relay contact is connected with a power GRID, and the connection point is used as a fourth sampling point. The relay contacts of the INV group comprise relays INV_ R, INV _ S, INV _ T, INV _N which are respectively arranged in an R-phase circuit, an S-phase circuit, a T-phase circuit and an N-line circuit, the relay contacts of the MID group comprise relays MID_ R, MID _ S, MID _ T, MID _N which are respectively arranged in the R-phase circuit, the S-phase circuit, the T-phase circuit and the N-line circuit, and the inverter of the GRID group comprises relays GRID_ R, GRID _ S, GRID _ T, GRID _N which are respectively arranged in the R-phase circuit, the S-phase circuit, the T-phase circuit and the N-line circuit.

In specific implementation, the controller controls the N-line relay to be tested to be turned off, and obtains voltage detection signals at two ends of the N-line relay to be tested; and judging whether the N-line relay to be tested is normally turned off or not according to the voltage detection signal.

The embodiment provides an inverter detection device, is applied to three-phase inverter circuit, inverter detection device includes: the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first resistive device is connected with any non-N-line relay to be tested in series; the first end of the second resistive device is connected with the first end of the first resistive device, and the second end of the second resistive device is connected with an N-line circuit of the three-phase inverter circuit to be tested; the voltage detection circuit is connected with the relay to be detected to acquire a voltage detection signal; the controller is connected with the relay to be tested and the voltage detection circuit to control the on and off of the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal. Therefore, according to the technical scheme provided by the application, the first resistive device and the second resistive device are arranged on any non-N-line circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the N-line voltage is changed, and whether the relay in the circuit is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved. .

In a specific implementation, the relays of different groups are respectively arranged in the circuits of different phases so as to control the on and off of the circuits of different phases. In the working process of the inverter, the relays are required to be matched in a coordinated manner so as to realize grid-connected operation of the inverter and the power grid and separation operation of the inverter and the power grid. In order to ensure the voltage balance of each phase circuit in the grid-connected process, the on-off time of the relay in each phase circuit is required to be consistent so as to prevent the faults of components and inverter loads in the inverter. To solve this problem, different relays may be controlled using the same drive. Based on the above embodiment, the MID group relay shares the hardware drive, and the relays provided on the non-N-wire circuit in the GRID group relay share the hardware drive.

In addition to detecting the N-line relay, the controller is also used for acquiring the voltage difference value of the two ends of the non-N-line relay to be detected of the GRID group relay so as to determine whether the non-N-line relay to be detected is normally turned off or not. In specific implementation, the controller controls the on and off of the R, S and T relays in the GRID group relay, and obtains the voltage difference between the two ends of the turned off relay, thereby determining whether to normally turn off. For example: when the adhesion normal turn-off does not occur, the voltage at the two ends of the relay is 230V, and when the adhesion occurs, the voltage at the two ends of the relay is 0V.

During switching of the switching device, high frequency variations in energy in parasitic elements (e.g., parasitic capacitance, parasitic inductance, etc.) create a significant amount of power electromagnetic interference (Electromagnetic Interference, EMI). EMI signals occupy a wide frequency range and have a certain amplitude, and through conduction and radiation in circuits and spaces, pollute the surrounding electromagnetic environment and influence the electromagnetic compatibility (Electromagnetic Compatibility) with other electronic devices. To prevent power electromagnetic interference from interfering with the inverter and other circuit components. On the basis of the embodiment, the inverter detection device further comprises a first capacitor, a second capacitor and a third capacitor to inhibit electromagnetic interference of a power supply; the first end of the first capacitor is connected with an R-phase circuit of the three-phase inverter circuit, and the second end of the first capacitor is connected with an N-line circuit of the three-phase inverter circuit; the first end of the second capacitor is connected with an S-phase circuit of the three-phase inverter circuit, and the second end of the second capacitor is connected with an N-line circuit of the three-phase inverter circuit; the first end of the third capacitor is connected with the T-phase circuit of the three-phase inverter circuit, and the second end of the third capacitor is connected with the N-line circuit of the three-phase inverter circuit.

Fig. 3 is a flowchart of a control method of an inverter detection device according to an embodiment of the present application, where, as shown in fig. 3, the control method of an inverter detection device according to the present application is applied to an inverter detection device including a controller, a voltage detection circuit, a first resistive device, and a second resistive device; the first resistive device is connected with any non-N-line relay to be tested in series; the first end of the second resistive device is connected with the first end of the first resistive device, and the second end of the second resistive device is connected with an N-line circuit of the three-phase inverter circuit to be tested; the voltage detection circuit is connected with the N-line relays to be detected, and the controller is connected with each relay to be detected and each voltage detection circuit; the inverter detection device control method comprises the following steps:

S10: the method comprises the steps of controlling the N-line relay to be tested to be turned off, and obtaining voltage detection signals at two ends of the N-line relay to be tested;

S11: and judging whether the N-line relay to be tested is normally turned off or not according to the voltage detection signal.

In this embodiment, the present application provides a control method of an inverter detection device, which is applied to a device including: the inverter detection device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first resistive device is connected with any non-N-line relay to be tested in series; the first end of the second resistive device is connected with the first end of the first resistive device, and the second end of the second resistive device is connected with an N-line circuit of the three-phase inverter circuit to be tested; the voltage detection circuit is connected with the relay to be detected to acquire a voltage detection signal; the controller is connected with the relay to be tested and the voltage detection circuit to control the on and off of the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal. Therefore, according to the technical scheme provided by the application, the first resistive device and the second resistive device are arranged on any non-N-line circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the N-line voltage is changed, and whether the relay is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved.

In a specific implementation, determining whether the N-wire relay to be tested is normally turned off according to the voltage detection signal includes: acquiring a first voltage value of a connection point of the first resistive device and the second resistive device and a second voltage value of the N-line relay to be tested; acquiring a first sampling voltage difference value of a third sampling point and a fourth sampling point in the N-line circuit, and judging whether the first sampling voltage difference value is equal to a difference value of a first voltage value and a second voltage value; and if so, determining that the N-line relay to be tested is not normally turned off. Fig. 4 is a schematic diagram of detecting a GRID group neutral line relay according to an embodiment of the present application, and fig. 5 is another schematic diagram of detecting a GRID group neutral line relay according to an embodiment of the present application, where, as shown in fig. 4 or fig. 5, first resistive devices are connected to two ends of a MIDR relay, so that a GRIDN voltage value to ground is a first voltage value. And a second resistive device is connected between the MIDR relay and the MIDN relay, so that MIDN has a second voltage value to the ground. When GRIDN relay is not adhered, the difference value of the sampling voltage between the third sampling point and the fourth sampling point is equal to the difference value of the first voltage value and the second voltage value; when GRIDN relay is adhered, the sampling voltage between the third sampling point and the fourth sampling point is equal to 230V, and the difference value is 0.

Fig. 6 is a schematic diagram of detecting a GRID group live wire relay according to an embodiment of the present application, as shown in fig. 6, in the testing process, a GRIDN relay is closed, a controller respectively controls a GRIDR relay, a GRIDS relay and a GRIDT relay to be opened, and obtains voltage difference values of two ends of the opened relay, if the voltage difference value of two ends of the relay is 230V or an error with 230V is smaller than a threshold value, it is determined that the relay is not adhered, otherwise, adhesion of the relay is indicated.

Furthermore, in the technical scheme provided by the application, the controller is also used for switching on and switching off other groups of relays so as to judge whether each relay is stuck or not. In a specific implementation, after the GRID group relay is judged, in order to ensure the safety of a circuit, when the GRID group relay is in an actuation state, the INV group relay and the MID group relay are detected to judge whether each relay can be normally turned off.

Specifically, a third sampling voltage difference value of the second sampling point and the third sampling point is obtained; judging whether the third sampling voltage difference value is larger than a fourth voltage threshold value; if the voltage is not greater than the fourth voltage threshold, determining that the MID group relay is abnormal in turn-off; if the alternating current effective value of the first sampling point is larger than the fourth voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than the second threshold value and smaller than the third threshold value; if the alternating current effective value of the first sampling point is larger than the second threshold value and smaller than the third threshold value, determining that the INV group relay is normally turned off; otherwise, determining that the INV group relay is turned off abnormally.

Specifically, when detecting the midgroup relay, the controller acquires a second sampling voltage difference value of a second sampling point and a third sampling point; judging whether the second sampling voltage difference value is larger than a first voltage threshold value or not; if the voltage is not greater than the first voltage threshold, determining that the MID group relay is abnormal in turn-off; if the alternating current effective value is larger than the first voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than the second voltage threshold value and smaller than the third voltage threshold value; if the alternating current effective value of the first sampling point is larger than the second voltage threshold and smaller than the third voltage threshold, determining that the MID group relay is normally turned off; otherwise, determining that the MID group relay is turned off abnormally.

When the INV group relay is detected; acquiring a third sampling voltage difference value of the second sampling point and the third sampling point; judging whether the third sampling voltage difference value is larger than a fourth voltage threshold value; if the voltage is not greater than the fourth voltage threshold, determining that the MID group relay is abnormal in turn-off; if the alternating current effective value of the first sampling point is larger than the fourth voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than the second threshold value and smaller than the third threshold value; if the alternating current effective value of the first sampling point is larger than the second threshold value and smaller than the third threshold value, determining that the INV group relay is normally turned off; otherwise, determining that the INV group relay is turned off abnormally.

In a specific implementation, the photovoltaic inverter has two working states of voltage and no voltage of a BUS BUS. When the BUS is in a non-voltage working state, the working condition of the direct current power supply with load is also detected by a relay. When the BUS BUS has a voltage working state, the direct current component exists in the INV-V voltage obtained at the first sampling point, so that the alternating current effective value of the sampling voltage at the first sampling point is adopted for judgment, the judgment logic and the threshold value are unified, and the interference of the direct current component is eliminated.

In a specific implementation, by combining the threshold difference value between sampling points and the voltage alternating current effective value, different adhesion conditions in the circuit can be detected, and fig. 7 to 22 are schematic diagrams and equivalent circuit diagrams of different adhesion conditions provided by the embodiment of the application.

When the MID group relays are not adhered, the voltage difference between the MID sampling point and the LOAD sampling point is 230V (greater than a first threshold value), and the effective alternating current value at the INV sampling point is greater than a second threshold value and less than a third threshold value; fig. 7 is an equivalent circuit diagram of all on of a GRID group relay according to an embodiment of the present application, as shown in fig. 7, the resistors in the diagram are all sampling high resistors, the first capacitor C1 is a LOAD end X capacitor, and 1.5V is a sampling reference. The voltage alternating current effective value (INVR-V-ACRMS), namely R3, is the voltage preset value, and the alternating current effective value of the RST three-phase circuit is the same.

Fig. 8 is a block diagram of sticking of an midp relay provided in an embodiment of the present application, as shown in fig. 8, when the midp_r relay is in a stuck state, the R1 resistor is bypassed, the R3 voltage division becomes larger to increase INV-V-ACRMS until the voltage is greater than a third threshold, and the controller determines that the midp relay is in a stuck state according to an ac effective value. The detection process of the mid_d relay and the mid_t relay is similar, and will not be described in detail here.

Fig. 9 is a block diagram of a MIDN relay sticking structure provided by an embodiment of the present application, fig. 10 is an equivalent circuit diagram of a MIDN relay sticking structure provided by an embodiment of the present application, as shown in fig. 9 and fig. 10, a resistor R3 in a loop is shorted by a capacitor C1, an ac equivalent value at a first sampling point is 0V, which is smaller than a second voltage threshold, and a controller determines that an mid_n relay is in a sticking state.

Fig. 11 is a block diagram of a structure in which MIDN and an MIDR relay are simultaneously stuck, which is provided by an embodiment of the present application, and fig. 12 is an equivalent circuit diagram of a structure in which MIDN and an MIDR relay are simultaneously stuck, when an mid_r relay and a MIDN relay are simultaneously in a stuck state, a sampling voltage value of a third sampling point and a sampling voltage value of a second sampling point are equal, a difference value is 0 and is smaller than a first voltage threshold, and an ac effective value at the first sampling point is 0 and is smaller than a second voltage threshold.

Fig. 13 is a block diagram of a simultaneous sticking of a midp relay and a midp relay provided by an embodiment of the present application, and fig. 14 is an equivalent circuit diagram of a simultaneous sticking of a midp relay and a midp relay provided by an embodiment of the present application, in which a sampling voltage value of a third sampling point is still 230V, but X capacitors C1 and C2 divide a line voltage, so that a sampling voltage value of a second sampling point becomes larger, and a difference between the sampling voltage value of the third sampling point and the sampling voltage value of the second sampling point is reduced, which is smaller than a first voltage threshold.

Fig. 15 is a block diagram of a single INV group live wire relay sticking, and fig. 16 is an equivalent circuit diagram of a single INV group live wire relay sticking, according to an embodiment of the present application, where a voltage ac effective value (INV-V-ACRMS) is a voltage across a capacitor C1, and does not satisfy a requirement of being greater than a second threshold and less than a third threshold.

Fig. 17 is a block diagram of sticking of a single INV group zero line relay provided by an embodiment of the present application, and fig. 18 is an equivalent circuit diagram of sticking of a single INV group zero line relay provided by an embodiment of the present application, as shown in the drawing, in this state, a voltage ac effective value (INV-V-ACRMS) is 0, which is smaller than a second threshold.

Fig. 19 is a block diagram of all the adhesion of the INV group relay provided by the embodiment of the present application, fig. 20 is an equivalent circuit diagram of all the adhesion of the INV group relay provided by the embodiment of the present application, for convenience of explanation, fig. 19 and fig. 20 only show that one live wire and zero wire are adhered, but in the implementation, all the relays on the live wire and the relays on the zero wire in the INV group relay are adhered, and in this state, the voltage ac effective value (INV-V-ACRMS) is 0 and is smaller than the second threshold value.

Fig. 21 is a block diagram of all the adhesion of the live wire relay of the INV group provided by the embodiment of the present application, fig. 22 is an equivalent circuit diagram of all the adhesion of the live wire relay of the INV group provided by the embodiment of the present application, for convenience of explanation, only one live wire and zero wire are shown in fig. 21 and 22, but in the specific implementation, all the relays on three live wires in the INV group relay are adhered, and in this state, the voltage ac effective value (INV-V-ACRMS) is 0 and less than the second threshold value.

It can be seen that in the implementation, the state of each relay under different conditions can be accurately judged by combining the effective value of the alternating voltage obtained at the first sampling point and the voltage difference value at the two ends of the relay, so as to determine whether the adhesion relay exists.

In addition, the application also provides a photovoltaic inverter comprising the inverter detection device, wherein the inverter detection device comprises: the device comprises a controller, a voltage detection circuit, a first resistive device and a second resistive device; the first resistive device is connected with any non-N-line relay to be tested in series; the first end of the second resistive device is connected with the first end of the first resistive device, and the second end of the second resistive device is connected with an N-line circuit of the three-phase inverter circuit to be tested; the voltage detection circuit is connected with the relay to be detected to acquire a voltage detection signal; the controller is connected with the relay to be tested and the voltage detection circuit to control the on and off of the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal. Therefore, according to the technical scheme provided by the application, the first resistive device and the second resistive device are arranged on any non-N-line circuit, so that the phase load is changed, the voltage balance in the multiphase circuit is further destroyed, the N-line voltage is changed, and whether the relay of the N-line circuit is disconnected is judged. Compared with the prior art, whether the relay is closed or not is judged only according to the voltage difference between two ends of the relay, the technical scheme provided by the application has the advantages that the N-line relay is detected by setting the first resistive device and the second resistive device to cause disturbance by N-line voltage, the N-line relay can be normally detected when all the live wire relay is stuck, and the detection accuracy and reliability are effectively improved.

The inverter detection device, the control method thereof and the photovoltaic inverter provided by the application are described in detail. In the description, each embodiment is described in a progressive manner, and each embodiment is mainly described by the differences from other embodiments, so that the same similar parts among the embodiments are mutually referred. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant points refer to the description of the method section. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the application can be made without departing from the principles of the application and these modifications and adaptations are intended to be within the scope of the application as defined in the following claims.

It should also be noted that in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Claims (10)

1. An inverter detection device, characterized by being applied to a three-phase inverter circuit, comprising:

the device comprises a controller (1), a voltage detection circuit (2), a first resistive device (3) and a second resistive device (4);

the first end of the first resistive device (3) is connected with the first end of the target relay contact, the second end of the first resistive device (3) and the first end of the second resistive device (4) are connected with the second end of the target relay contact, and the second end of the second resistive device (4) is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit;

The voltage detection circuit (2) is connected with the three-phase inverter circuit to acquire a voltage detection signal;

the controller (1) is connected with the relay to be tested and the voltage detection circuit (2) so as to send a turn-off signal to the relay to be tested, and judges whether the relay to be tested is normally turned off or not according to the voltage detection signal.

2. The inverter detection device according to claim 1, wherein the relay of the three-phase inverter circuit includes: INV group relay, MID group relay, and GRID group inverter;

the first end of the INV group relay contact is connected with the output end of the inverter, and the connection point is used as a first sampling point;

The second end of the contact of the INV group relay is connected with the first end of the contact of the MID group relay, and the connection point is used as a second sampling point;

the second end of the MID group relay contact is connected with the first end of the GRID group relay contact, and the connection point is used as a third sampling point;

And the second end of the GRID group relay contact is connected with a power GRID, and the connection point is used as a fourth sampling point.

3. The inverter detection device according to claim 2, wherein the MID group relay shares a hardware drive, and the relays provided on the hot line of the three-phase inverter circuit in the GRID group relay share a hardware drive.

4. The inverter detection device according to claim 2, wherein the controller (1) is further configured to obtain a voltage difference value across a relay to be tested of the GRID group relay, so as to determine whether the relay to be tested is normally turned off.

5. The inverter detection device of claim 1 further comprising a first capacitor, a second capacitor, a third capacitor to suppress electromagnetic interference of a power source;

The first end of the first capacitor is connected with an R-phase circuit of the three-phase inverter circuit, and the second end of the first capacitor is connected with an N-line circuit of the three-phase inverter circuit;

the first end of the second capacitor is connected with an S-phase circuit of the three-phase inverter circuit, and the second end of the second capacitor is connected with an N-line circuit of the three-phase inverter circuit;

the first end of the third capacitor is connected with the T-phase circuit of the three-phase inverter circuit, and the second end of the third capacitor is connected with the N-line circuit of the three-phase inverter circuit.

6. The control method of the inverter detection device is characterized by being applied to the inverter detection device comprising a controller (1), a voltage detection circuit (2), a first resistive device (3) and a second resistive device (4); the first end of the first resistive device (3) is connected with the first end of the target relay contact, the second end of the first resistive device (3) and the first end of the second resistive device (4) are connected with the second end of the target relay contact, and the second end of the second resistive device (4) is connected with a zero line of the three-phase inverter circuit; the target relay is a relay arranged on any phase fire wire of the three-phase inverter circuit; the voltage detection circuit (2) is connected with a zero line of the three-phase inverter circuit; the inverter detection device control method comprises the following steps:

The method comprises the steps of controlling a relay to be tested to be turned off, and obtaining voltage detection signals at two ends of the relay to be tested;

And judging whether the relay to be tested is normally turned off or not according to the voltage detection signal.

7. The inverter detection device control method according to claim 6, wherein the determining whether the relay to be tested is normally turned off according to the voltage detection signal includes:

Acquiring a first voltage value of a connection point of the first resistive device (3) and the second resistive device (4) and a second voltage value of a second end of the relay to be tested;

acquiring a first sampling voltage difference value of a third sampling point and a fourth sampling point in a zero line of the three-phase inverter circuit, and judging whether the first sampling voltage difference value is equal to a difference value between the first voltage value and the second voltage value;

And if so, determining that the relay to be tested is not normally turned off.

8. The inverter detection device control method according to claim 6, characterized by further comprising:

Acquiring a second sampling voltage difference value, wherein the second sampling voltage difference value is the voltage difference value of a second sampling point and a third sampling point;

Judging whether the second sampling voltage difference value is larger than a first voltage threshold value or not;

if the voltage is not greater than the first voltage threshold, determining that the MID group relay is abnormal in turn-off;

If the alternating current effective value of the first sampling point is larger than the first voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than the second voltage threshold value and smaller than a third voltage threshold value;

If the alternating current effective value of the first sampling point is larger than the second voltage threshold and smaller than the third voltage threshold, determining that the MID group relay is normally turned off;

otherwise, determining that the MID group relay is turned off abnormally.

9. The inverter detection device control method according to claim 8, characterized by further comprising:

Acquiring a third sampling voltage difference value of the second sampling point and the third sampling point;

judging whether the third sampling voltage difference value is larger than a fourth voltage threshold value or not;

if the voltage is not greater than the fourth voltage threshold, determining that the MID group relay is abnormal in turn-off;

if the alternating current effective value of the first sampling point is larger than the fourth voltage threshold value, determining whether the alternating current effective value of the first sampling point is larger than a second threshold value and smaller than a third threshold value;

If the alternating current effective value of the first sampling point is larger than a second threshold value and smaller than a third threshold value, determining that the INV group relay is normally turned off;

otherwise, determining that the INV group relay is turned off abnormally.

10. A photovoltaic inverter comprising the inverter detection apparatus according to any one of claims 1 to 5.