Fault detection device for photovoltaic inverter and use method thereof

Abstract

The invention discloses a fault detection device for a photovoltaic inverter and a use method thereof, and relates to the technical field of inverter fault detection.The fault detection device comprises a protection frame and further comprises a working system and a circuit breaking assembly, and a direct-current input end, an inverter body and an alternating-current output end are sequentially and electrically connected in series in the protection frame; the working system comprises a detection module, a control core and an execution mechanism which are electrically connected in series in sequence. The circuit breaking assembly comprises a driving mechanism, a pop-up mechanism and a disconnection mechanism which are arranged on the two sides of the inverter body and are connected in series in sequence. According to the invention, by arranging the working system, the input end and the output end of the inverter are detected at the same time, and the corresponding execution mechanism is controlled to realize disconnection operation according to the detected fault type; according to the invention, the circuit breaking assembly is arranged, and the pop-up mechanism is arranged, so that the breaking mechanism executes a quick pop-up action, and the response time of the breaking process is greatly shortened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inverter fault detection, in particular to a fault detection device for a photovoltaic inverter and a method thereof. BACKGROUND

[0002] The photovoltaic inverter is the core equipment of the solar power generation system, and its main function is to convert the direct current generated by the photovoltaic module into alternating current, so that it can be connected to the power grid or used for local load. In addition, the inverter also undertakes the key tasks of maximum power point tracking, system protection, data monitoring, etc., but the photovoltaic inverter is exposed to complex environments such as high temperature, humidity, lightning for a long time, and is prone to failure and loss of power generation or even safety accidents.

[0003] According to the search, the patent with the publication number CN119959710B includes an inverter body and a shell sleeved outside the inverter body. The lower end of the inverter body is provided with a power switch, and the side has a transformer fixedly connected with the shell. There is also a detection device electrically connected with the power switch. The detection device is provided with an electromagnetic drive circuit-breaking mechanism, which includes an electromagnetic coil, a core, a moving contact and a static contact. When the detection device detects an arc fault signal of the power switch, it sends a current pulse to the electromagnetic coil to make it generate a magnetic field. The core drives the moving contact away from the static contact. The power switch has a fan for cooling. The transformer has a protection mechanism composed of an insulating cover and an insulating baffle. When the moving contact and the static contact are separated, the insulating cover moves towards the transformer and covers the transformer. Then the insulating baffle abuts against the insulating cover to play a protection role. The above-mentioned device can detect the fault in the inverter and cool and insulate the fault area.

[0004] However, the detection method of the photovoltaic inverter in the above-mentioned scheme mainly focuses on the electrical safety inside the inverter system, and lacks detection of the output end of the inverter. When the external power grid is disconnected due to failure, the photovoltaic inverter is still supplying power to the local load, forming an uncontrolled independent power supply system, which threatens personal safety. At the same time, island operation may lead to voltage / frequency out of control, damaging the inverter or load, and when the power grid is reconnected, a large current impact may be caused due to different phase synchronization. Therefore, the detection method of the above-mentioned scheme is relatively single, and it is difficult to meet the protection and safety requirements of the photovoltaic inverter. On the other hand, the above-mentioned scheme uses the contact between the moving contact and the static contact to control the conduction of the circuit, and the arc exists during the disconnection process, which makes the disconnection response stroke longer and the arc easy to damage the contact. In addition, the contact area between the moving contact and the static contact is small, and the current conduction efficiency is low. SUMMARY

[0005] The purpose of the present application is to provide a fault detection device for a photovoltaic inverter and a method thereof, which has the advantages of composite detection and voltage discharge, and solves the problems raised in the background art.

[0006] In order to achieve the above object, the present application provides the following technical scheme: a fault detection device for a photovoltaic inverter, comprising a protective frame, further comprising a working system and a circuit breaking assembly, the inside of the protective frame is sequentially and electrically connected with a DC input end, an inverter main body and an AC output end, wherein the DC input end is arranged on the left side in the protective frame, the inverter main body is arranged on the middle section in the protective frame, and the AC output end is arranged on the right side in the protective frame. The working system comprises a detection module, a control core and an execution mechanism which are sequentially and electrically connected, wherein the detection module comprises arc detection units and island detection units arranged on both sides above the protective frame, the control core comprises a priority arbitration unit arranged at the middle position in the protective frame, and the execution mechanism comprises DC side execution units and AC side execution units arranged on both sides below the priority arbitration unit. The circuit breaking assembly comprises a driving mechanism, a pop-up mechanism and a disconnecting mechanism which are sequentially and connected and arranged on both sides of the inverter main body, the driving mechanism is signal connected with the corresponding position execution mechanism, and the disconnecting mechanism is electrically connected with the corresponding position execution mechanism.

[0007] Preferably, the arc detection unit is used for detecting the DC signal of the DC input end, the arc detection unit is provided with a high-frequency cable mutual inductor, a band-pass filter and a logarithmic amplifier which are sequentially and connected and used for detecting the high-frequency signal of the DC input end, and the arc detection unit is further provided with a Rogowski coil and an integrator which are sequentially and connected and used for detecting the current mutation of the DC input end, and the output ends of the logarithmic amplifier and the integrator are commonly connected with a comparator one. The island detection unit is used for detecting the AC signal of the AC output end, the island detection unit is provided with a voltage mutual inductor, a phase-locked loop, a frequency converter and a comparator two which are sequentially and connected, and the output end of the comparator two and the output end of the comparator one are commonly connected to the priority arbitration unit.

[0008] Preferably, the priority arbitration unit completes the arbitration judgment of the input signal, the inside of the priority arbitration unit is provided with an AND gate chip, an OR gate chip and a SiC drive chip which are sequentially and connected, and the output end of the SiC drive chip is commonly connected with the DC side execution unit and the AC side execution unit.

[0009] Preferably, the inside of the DC side execution unit and the AC side execution unit is provided with the circuit breaking assembly, the inside of the DC side execution unit is provided with a DC discharge circuit, and the DC discharge circuit is arranged at the input end of the circuit breaking assembly in the DC side execution unit.

[0010] Preferably, the driving mechanism comprises a motor controlled by a direct current side execution unit and an alternating current side execution unit, the output end of the motor is fixedly connected with a lead screw, the outer contour of the lead screw is screwed with a threaded sleeve, the upper and lower sides of the outer contour of the threaded sleeve are fixedly connected with guide rails, the outer sleeve of the threaded sleeve is sleeved with a fixed cylinder, the bottom end of the fixed cylinder is fixedly connected with a fixed seat one arranged on the inner wall of the bottom end of the protection frame, the motor is fixedly connected to one side of the fixed cylinder, the corresponding position of the surface of the fixed cylinder is provided with a sliding groove matched with the guide rail, and the end of the threaded sleeve away from the motor is fixedly connected with a connecting ring one.

[0011] Preferably, the ejection mechanism comprises a fixed frame arranged on the inner wall of the bottom end of the protection frame, the top end of the fixed frame is transversely penetrated by a transmission shaft, one end of the transmission shaft is fixedly connected with a connecting ring two, the connecting ring two and the connecting ring one are fixedly connected with a connecting spring, the middle segment of the transmission shaft is fixedly connected with a fixed ring, the middle segment of the transmission shaft is penetrated by a movable frame, the movable frame is located in the interior of the fixed frame, the bottom end of the movable frame is provided with inclined grooves on both sides, and the inner contours of the two sides of the movable frame and the fixed ring are fixedly connected with compression springs two sleeved on the outer contour of the transmission shaft. The middle segment of the bottom end of the fixed frame is provided with a compression spring one, the top end of the compression spring one is fixedly connected with a positioning pin extending into the fixed frame, and the positioning pin and the inclined groove are abuttingly connected.

[0012] Preferably, the disconnecting mechanism comprises a fixed seat two arranged on the inner wall of the bottom end of the protection frame, the top end of the fixed seat two is fixedly connected with a closed cylinder, one end in the interior of the closed cylinder is fixedly connected with a static contact, the inner wall of the closed cylinder is provided with a limiting cylinder at one end of the static contact, the end of the interior of the closed cylinder away from the static contact is fixedly connected with a closed ring, the interior of the closed cylinder is sleeved with a movable cylinder, the surface of the movable cylinder is provided with limiting grooves matched with the closed ring on both upper and lower sides, the interior of the movable cylinder is fixedly connected with a dynamic contact, the end of the movable cylinder away from the static contact is fixedly connected with the end of the transmission shaft away from the connecting ring two, the end of the dynamic contact away from the transmission shaft is abuttingly connected with the static contact, the inner wall of the end of the movable cylinder close to the static contact is fixedly connected with a positioning cylinder, and the inner wall of the positioning cylinder is fixedly connected with a positioning ring matched in size with the static contact.

[0013] Preferably, a method for using a photovoltaic inverter fault detection device comprises the following steps: S1, fault detection: using the detection module in the working system to detect the input process of the direct current input end to the inverter main body and the output process of the inverter main body to the alternating current output end, and inputting the detected data signal into the control core synchronously; S2, priority judgment: according to the signal input by the detection module, the fault type in the inverter is judged, and the corresponding disconnection work of the actuator is controlled according to the fault type; S3, fault analysis: when the fault type is arc fault, the DC side execution unit starts to work and controls the circuit breaker assembly to disconnect the input process of the DC input end to the inverter main body, and according to the arc type detected by the arc detection unit, the DC discharge circuit in the DC side execution unit is controlled to work correspondingly; when the fault type is island fault, the AC side execution unit starts to work and disconnects the output process of the inverter main body to the AC output end; when the fault type is composite fault, the DC side execution unit works preferentially and controls the circuit breaker assembly to disconnect the input process of the DC input end to the inverter main body, and then starts the DC discharge circuit, and after confirming that the DC voltage drops to the safety threshold, the AC side execution unit controls the circuit breaker assembly to disconnect the output process of the inverter main body to the AC output end; S4, circuit breaking execution: when the circuit breaker assembly works, the drive mechanism controls the ejection mechanism to start, and the ejection mechanism further controls the disconnection mechanism to eject and disconnect.

[0014] Compared with the prior art, the beneficial effects of the present application are as follows: 1、The present application detects the input end and output end of the inverter simultaneously by setting the detection module, control core and execution mechanism, and controls the corresponding execution mechanism to realize disconnection work according to the detected fault type, which is more comprehensive in protection effect and greatly improves safety.

[0015] 2、The present application sets a circuit breaker assembly, which uses the setting of the ejection mechanism to make the disconnection mechanism perform a rapid ejection action, greatly shortening the response time of the disconnection process and further reducing the risk of arc damage to the contact.

[0016] 3、The disconnection mechanism of the present application is fully enclosed, which can effectively avoid the damage of arc escape to other electrical elements, and at the same time, the rapid extinguishing of arc by the filled sulfur hexafluoride gas inside further reduces the duration of arc. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic diagram of the main structure of the present application; Figure 2 is a connection sequence diagram of the arc detection unit of the present application; Figure 3 is a connection sequence diagram of the island detection unit of the present application; Figure 4 is a connection sequence diagram of the priority arbitration unit of the present application; Figure 5 is a working flow chart of the DC discharge circuit of the present application; Figure 6 is an explosion diagram of the drive mechanism of the present application; Figure 7 It is the pop-up mechanism sectional view of the application; Figure 8 It is the schematic diagram of the application disconnect mechanism; Figure 9 It is the overall workflow diagram of the application.

[0018] In the figure: 1, protective frame; 11, inverter main body; 12, DC input end; 13, AC output end; 2, arc detection unit; 21, high-frequency cable transformer; 22, band-pass filter; 23, logarithmic amplifier; 24, Rogowski coil; 25, integrator; 26, comparator I; 3, island detection unit; 31, voltage transformer; 32, phase-locked loop; 33, frequency converter; 34, comparator II; 4, priority arbitration unit; 41, AND gate chip; 42, OR gate chip; 43, SiC drive chip; 5, DC side execution unit; 6, AC side execution unit; 7, motor; 71, screw rod; 72, threaded sleeve; 73, guide rail; 74, fixed cylinder; 75, sliding groove; 76, fixed seat I; 77, connecting ring I; 8, fixed frame; 81, transmission shaft; 82, compression spring I; 83, positioning pin; 84, movable frame; 85, fixed ring; 86, inclined slot; 87, compression spring II; 88, connecting ring II; 89, connecting spring; 9, fixed seat II; 91, closed cylinder; 92, closed ring; 93, static contact; 94, limiting cylinder; 95, movable cylinder; 96, limiting groove; 97, moving contact; 98, positioning cylinder; 99, positioning ring. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0020] Embodiment one:

[0021] Please refer to Figures 1 to 9 The application provides a technical solution: a fault detection device for a photovoltaic inverter, comprising a protective frame 1, further comprising a working system and a circuit breaking assembly, the inside of the protective frame 1 is sequentially and electrically connected in series with a DC input end 12, an inverter main body 11 and an AC output end 13, wherein the DC input end 12 is arranged on the left side in the protective frame 1, the inverter main body 11 is arranged in the middle section in the protective frame 1, and the AC output end 13 is arranged on the right side in the protective frame 1. The working system comprises a detection module, a control core and an execution mechanism which are electrically connected in sequence, wherein the detection module comprises arc detection units 2 and island detection units 3 arranged on both sides of the upper part of the protection frame 1, the control core comprises a priority arbitration unit 4 arranged at the middle position of the protection frame 1, and the execution mechanism comprises DC side execution units 5 and AC side execution units 6 arranged on both sides of the lower part of the priority arbitration unit 4. The circuit breaking assembly comprises a driving mechanism, a pop-up mechanism and a breaking mechanism arranged on both sides of the inverter main body 11 and connected in sequence, the driving mechanism is connected with the corresponding position execution mechanism signal, and the breaking mechanism is electrically connected with the corresponding position execution mechanism.

[0022] In the scheme, the synchronous detection of arc fault at the input end of the inverter and island fault at the output end is realized by designing the working system, different circuit breaking operations are performed according to the detected fault types, the protection performance of the inverter is further optimized, and the safety of personnel operation is greatly improved.

[0023] The arc detection units 2 are used for detecting arc fault during the input process of the DC input end 12 to the inverter main body 11 and sending signals to the priority arbitration unit 4, the priority arbitration unit 4 controls the DC side execution units 5 and the motor 7 to perform different breaking operations according to the fault type detected by the arc detection units 2; the island detection units 3 are used for detecting island fault during the output process of the inverter main body 11 to the AC output end 13 and sending signals to the priority arbitration unit 4, the priority arbitration unit 4 further controls the AC side execution units 6 and the motor 7 to perform breaking operations; if the arc fault and the island fault occur at the same time, the priority arbitration unit 4 receives two kinds of fault signals at the same time, and completes the priority arbitration judgment, the arc fault is preferentially processed, and the island fault is processed after the voltage is reduced to a safe threshold value by the DC discharge circuit.

[0024] On the other hand, the setting of the circuit breaking assembly limits the action of the breaking process, greatly reduces the response time of the breaking process, and limits the diffusion range of the arc, effectively avoiding the long-term continuation of the arc and the influence on the components.

[0025] The driving mechanism is controlled to start by the corresponding position DC side execution units 5 and AC side execution units 6, further drives the pop-up mechanism to run, the pop-up mechanism changes the action of the breaking mechanism into the form of rapid pop-up, and further greatly reduces the action time, so as to realize the purpose of rapid response.

[0026] Embodiment two:

[0027] The arc detection unit 2 is used for detecting the direct current signal of the direct current input end 12, and a high-frequency cable transformer 21, a band-pass filter 22 and a logarithmic amplifier 23 are sequentially connected in series in the arc detection unit 2, which is used for detecting the high-frequency signal of the direct current input end 12, and a Rogowski coil 24 and an integrator 25 are sequentially connected in series in the arc detection unit 2, which is used for detecting the current mutation of the direct current input end 12, and the output ends of the logarithmic amplifier 23 and the integrator 25 are commonly connected in parallel with a comparator one 26. The island detection unit 3 is used for detecting the alternating current signal of the alternating current output end 13, and a voltage transformer 31, a phase-locked loop 32, a frequency converter 33 and a comparator two 34 are sequentially connected in series in the island detection unit 3, and the output end of the comparator two 34 and the output end of the comparator one 26 are commonly connected in parallel to a priority arbitration unit 4.

[0028] The priority arbitration unit 4 completes the arbitration judgment of the input signal, and an AND gate chip 41, an OR gate chip 42 and a SiC drive chip 43 are sequentially connected in series in the priority arbitration unit 4, and the output end of the SiC drive chip 43 is commonly connected in parallel with a direct current side execution unit 5 and an alternating current side execution unit 6.

[0029] The direct current side execution unit 5 and the alternating current side execution unit 6 are both internally provided with a circuit breaking assembly, and the direct current side execution unit 5 is internally provided with a direct current discharge circuit, which is arranged at the input end of the circuit breaking assembly in the direct current side execution unit 5.

[0030] As known from the first embodiment, the arc detection unit 2 completes the arc detection of the input process of the direct current input end 12 to the inverter main body 11, wherein the high-frequency cable transformer 21 is used for capturing the high-frequency noise 100kHz-1MHz generated by the arc, especially the electromagnetic radiation signal of the parallel arc, and further outputting the voltage signal proportional to the high-frequency current amplitude; the band-pass filter 22 is used for filtering out the low-frequency noise and high-frequency switching noise in the output signal of the high-frequency cable transformer 21, while retaining the arc characteristic frequency band, and the cut-off frequency of the band-pass filter 22 is set to be 1MHz for low pass and 100kHz for high pass; the logarithmic amplifier 23 is used for compressing the dynamic range and converting the high-frequency signal amplitude into a linearly processable voltage, further avoiding signal overload and improving small signal sensitivity. It mainly processes the wide-amplitude high-frequency signal output by the high-frequency cable transformer 21.

[0031] Simultaneously, the Rogowski coil 24 is used to detect the instantaneous rate of change of current, identify the current discontinuous characteristics of series arc, and its output signal is further reduced to the current waveform by the integrator 25, and the time constant of the integrator 25 is usually set to 100 μs; the comparator 26 is used to set the dynamic threshold to determine whether the arc characteristic signal is out of limit, and outputs a digital level to the priority arbitration unit 4 and realizes hardware logic arbitration through the priority arbitration unit 4 to combine the determination results of the high-frequency cable transformer 21 and the Rogowski coil 24.

[0032] Similarly, the island detection unit 3 completes island detection on the output process of the inverter main body 11 to the AC output end 13, wherein the voltage transformer 31 is used to collect the AC voltage signal of the AC output end 13 in real time, provide amplitude and phase information, and the key parameters are set to an input range of ±500 V and a linearity of 0.1%, which directly monitors the state of the AC output end 13 and is the basis of island determination; the phase-locked loop 32 is used to track the voltage frequency of the AC output end 13 at 50 Hz / 60 Hz, detect the frequency deviation such as >50.5 Hz or <49.5 Hz, and output a frequency error signal to the comparator 34; the frequency converter 33 is used to convert the frequency signal output by the phase-locked loop 32 into an analog voltage for subsequent determination by the comparator 34 whether the frequency is out of limit, and the frequency threshold is set to 49.5 Hz→0.495 V and 50.5 Hz→0.505 V; the comparator 34 determines whether the frequency / voltage is out of the allowed range and outputs a digital signal to the priority arbitration unit 4 to trigger the protection logic.

[0033] Further, the priority arbitration unit 4 completes the priority determination of the input signal, wherein the AND gate chip 41 realizes logical AND operation to combine the output signals of the arc detection unit 2, ensures that the protection is triggered only when the arc signal and the auxiliary verification signal are valid at the same time, for example, when the arc high-frequency energy is out of limit and the current suddenly changes, that is, the high-frequency cable transformer 21 and the Rogowski coil 24 output signals at the same time, then the determination is true arc, thereby effectively reducing the false alarm rate; the OR gate chip 42 realizes logical OR operation for fault priority arbitration, and sets the output signal of the arc detection unit 2 as high priority and the output signal of the island detection unit 3 as secondary priority, thereby ensuring that the arc fault is prior to the island fault processing, and meeting the actual scene that the arc fault safety risk is much higher than the island fault safety risk; the SiC drive chip 43 generates a fixed delay for island protection action, ensures that the DC side is discharged first to avoid that the DC energy cannot be discharged due to the premature disconnection of the AC side, and at the same time amplifies the logic signal current to quickly drive the DC side execution unit 5 or the AC side execution unit 6 and the circuit breaking component to start.

[0034] As can be seen from the above, when the inverter body 11 has an arc fault and the arc type is series arc, that is, the cable is broken or the connection is loose, causing the current to suddenly interrupt, at this time the current rate of change detected by the Rogowski coil 24 abnormally rises, the Rogowski coil 24 channel dominates the judgment in the process, the high-frequency cable transformer 21 channel assists filtering, and the priority arbitration unit 4 further drives the direct current side execution unit 5 and its direct current discharge circuit to start working, at this time the direct current input end 12 shuts down the input process to the inverter body 11; Similarly, when the arc type is parallel arc, that is, the insulation between the positive and negative electrodes is damaged to produce discharge, at this time the high-frequency cable transformer 21 detects high-frequency electromagnetic noise, the high-frequency cable transformer 21 channel dominates the judgment in the process, the Rogowski coil 24 channel assists verification, and the priority arbitration unit 4 also controls the direct current side to shut down, and the discharge rate is faster than that when the series arc occurs.

[0035] Further, when the inverter body 11 has an island fault, that is, the power grid is powered off but the inverter body 11 still supplies power to the alternating current output end 13, at this time the island detection unit 3 outputs a signal to the priority arbitration unit 4, and the priority arbitration unit 4 further controls the alternating current side execution unit 6 and the circuit breaking assembly to complete the alternating current side shutdown operation; When the inverter body 11 has a composite fault, the arc detection unit 2 and the island detection unit 3 simultaneously output signals to the priority arbitration unit 4, the priority arbitration unit 4 preferentially processes the arc fault signal of the arc detection unit 2, and after a fixed delay, processes the island fault signal of the island detection unit 3.

[0036] Embodiment three:

[0037] The driving mechanism comprises a motor 7 which is started and stopped through signal control of the direct current side execution unit 5 and the alternating current side execution unit 6, the output end of the motor 7 is fixedly connected with a lead screw 71, the outer contour of the lead screw 71 is screwed with a threaded sleeve 72, the upper and lower sides of the outer contour of the threaded sleeve 72 are fixedly connected with guide rails 73, the threaded sleeve 72 is sleeved with a fixed cylinder 74 outside, the bottom end of the fixed cylinder 74 is fixedly connected with a fixed seat one 76 arranged on the inner wall of the bottom end of the protection frame 1, the motor 7 is fixedly connected to one side of the fixed cylinder 74, a sliding groove 75 matched with the guide rails 73 is formed in the corresponding position on the surface of the fixed cylinder 74, and one end of the threaded sleeve 72 away from the motor 7 is fixedly connected with a connecting ring one 77.

[0038] The pop-up mechanism includes a fixed frame 8 arranged on the inner wall of the bottom end of the protective frame 1, the top end of the fixed frame 8 is transversely penetrated by a transmission shaft 81, one end of the transmission shaft 81 is fixedly connected with a connecting ring two 88, the connecting ring two 88 and the connecting ring one 77 are fixedly connected with a connecting spring 89, the middle segment of the transmission shaft 81 is fixedly connected with a fixed ring 85, the transmission shaft 81 is penetrated by a movable frame 84, the movable frame 84 is located in the interior of the fixed frame 8, the bottom end of the movable frame 84 is provided with inclined grooves 86 on both sides, the inner contours of the two sides of the movable frame 84 and the fixed ring 85 are fixedly connected with compression springs two 87 which are sleeved on the outer contour of the transmission shaft 81. The middle segment of the bottom end of the fixed frame 8 is provided with a compression spring one 82, the top end of the compression spring one 82 is fixedly connected with a positioning pin 83 extending into the fixed frame 8, the positioning pin 83 and the inclined grooves 86 are abuttingly connected.

[0039] The disconnecting mechanism includes a fixed seat two 9 arranged on the inner wall of the bottom end of the protective frame 1, the top end of the fixed seat two 9 is fixedly connected with a closed cylinder 91, one end in the interior of the closed cylinder 91 is fixedly connected with a static contact 93, the inner wall of the closed cylinder 91 located at one end of the static contact 93 is provided with a limiting cylinder 94, the end of the interior of the closed cylinder 91 away from the static contact 93 is fixedly connected with a closed ring 92, the interior of the closed cylinder 91 is sleeved with a movable cylinder 95, the surface of the movable cylinder 95 is provided with limiting grooves 96 on the upper and lower sides which are adapted to the closed ring 92, the interior of the movable cylinder 95 is fixedly connected with a dynamic contact 97, the end of the movable cylinder 95 away from the static contact 93 is fixedly connected with the end of the transmission shaft 81 away from the connecting ring two 88, the end of the dynamic contact 97 away from the transmission shaft 81 is abuttingly connected with the static contact 93, the inner wall of the end of the movable cylinder 95 close to the static contact 93 is fixedly connected with a positioning cylinder 98, the inner wall of the positioning cylinder 98 is fixedly connected with a positioning ring 99 which is sized to adapt to the static contact 93.

[0040] As can be seen from the embodiments one and two, the circuit breaking assembly is driven to execute the turn-off action of the DC side and the AC side of the inverter body 11 through the working system, wherein the turn-off action of the DC side is determined after the discharge process, that is, when the arc fault occurs, the DC discharge circuit in the DC side execution unit 5 preferentially executes the discharge action, and when the voltage drops to the safety threshold, the circuit breaking assembly is further driven to execute the turn-off action, wherein the working logic of the DC discharge circuit is as shown in the figure Figure 5 According to the voltage value when the arc fault occurs, the resistance with the corresponding resistance value is switched, and then the rapid discharge action is completed until the voltage drops to below 60V, and the next turn-off action is executed.

[0041] In combination with Figure 1 and Figure 6As shown, when the shut-off action is in progress, the motor 7 receives the signal to start and drives the screw rod 71 to rotate. Since the fixing seat 76 and the fixing cylinder 74 are in a fixed state, the motor 7 is fixedly connected to one side of the fixing cylinder 74, that is, the positions of the motor 7, the fixing seat 76 and the fixing cylinder 74 cannot be changed. At this time, since the threaded sleeve 72 is screwed to the screw rod 71, the rotation of the screw rod 71 has a tendency to drive the threaded sleeve 72 to rotate synchronously, but the slide groove 75 is opened on the inner contour of the fixing cylinder 74, that is, the position of the slide groove 75 cannot be changed synchronously. At this time, the guide rail 73 slides When the screw rod 71 is rotated in the opposite direction, the threaded sleeve 72 will extend from the inside of the fixed cylinder 74 to the end away from the motor 7 and push the connecting ring 77 in the opposite direction.

[0042] Furthermore, for the pop-up mechanism, since the fixed frame 8 is fixed on the ground, the positions of the fixed frame 8 and the compression spring 82 cannot be changed, and the transmission shaft 81 is fixedly connected to the fixed ring 85, that is, the fixed frame 8 will drive the fixed ring 85 to move synchronously when it moves horizontally, and the movable frame 84 and the positioning pin 83 are abutted and clamped by the inclined groove 86, resulting in the movable frame 84 needing to overcome the elastic resistance of the compression spring 82 when it moves horizontally.

[0043] Therefore, Figure 7 For example, when the connecting ring 1 77 contracts along with the threaded sleeve 72 and pulls the connecting spring 89, the connecting spring 89 will be stretched and deformed, and has a tendency to drive the connecting ring 2 88 and the transmission shaft 81 to move to the left. The movable frame 84 remains stationary due to the abutment and engagement of the positioning pin 83 and the inclined groove 86. When the transmission shaft 81 and the fixed ring 85 move to the left, the fixed ring 85 will squeeze the compression spring 2 87 on the left side of the squeezer, causing it to undergo compression deformation. This part of the compression deformation further provides a driving force for the movable frame 84 to move to the left. When the elastic potential energy of the compression spring 2 87 is greater than the deformation modulus of the compression spring 1 82, the compression spring 2 The driving force provided by 87 to the movable frame 84 is greater than the resistance between the positioning pin 83 and the inclined slot 86. At this time, the positioning pin 83 gradually shrinks back into the interior of the fixed frame 8 under the squeezing of the movable frame 84 and the inclined slot 86, and the compression spring 1 82 is synchronously compressed until the positioning pin 83 is disengaged from the inclined slot 86. At this time, the resistance encountered by the movable frame 84 disappears, and it pops out quickly to the left under the release of the elastic potential energy of the compression spring 2 87. Synchronously, the resistance to the left movement of the transmission shaft 81 also disappears. At this time, the reset of the connecting spring 89 causes the connecting ring 2 88, the transmission shaft 81 and the fixed ring 85 to pop out quickly to the left as well.

[0044] Similarly, when the connecting ring 77 is extended along with the threaded sleeve 72, it also pushes the connecting spring 89, causing the connecting spring 89 to be compressed, at this time, the movement process of the ejection mechanism is opposite to the above process, eventually causing the transmission shaft 81 to be ejected to the right, and further converting the closing and opening actions of the disconnecting mechanism into a fast ejection mode, in order to achieve the purpose of fast response.

[0045] Further, when the transmission shaft 81 is ejected to the left, it pulls the movable cylinder 95 to be ejected synchronously, at this time, the movable contact 97, the positioning cylinder 98 and the positioning ring 99 move synchronously along with the fixed ring 85, the sleeve connection relationship between the movable contact 97 and the end of the static contact 93 is released, and the contact between the movable contact 97 and the static contact 93 is disconnected; In the process of gradually disconnecting the movable contact 97 and the static contact 93, a pull arc is generated between the ends thereof, and the inside of the fixed seat two 9 is filled with sulfur hexafluoride gas, through the setting of the sealing ring 92, the escape of sulfur hexafluoride gas is avoided, along with the process of the movable cylinder 95 being ejected to the left, the sulfur hexafluoride gas in the inside of the fixed seat two 9 contacts the pull arc between the movable contact 97 and the static contact 93, and then the arc extinguishing operation is realized. Due to the ejection action of the movable cylinder 95, the duration of the pull arc between the movable contact 97 and the static contact 93 is very short, in order to meet the purpose of fast arc extinguishing.

[0046] On the other hand, through the cooperation of the positioning cylinder 98 and the positioning ring 99, when the circuit is closed, the positioning ring 99 is sleeved outside the contact position of the movable contact 97 and the static contact 93, further preventing the sulfur hexafluoride gas from entering the contact point of the movable contact 97 and the static contact 93 to affect the current conduction efficiency; At the same time, by using the cooperation of the limiting cylinder 94 and the movable cylinder 95, the movable cylinder 95 is prevented from colliding between the ends of the movable contact 97 and the static contact 93 during the closing action of being ejected to the right, so as to affect the service life.

[0047] Example four:

[0048] A use method of a photovoltaic inverter fault detection device, comprising the following steps: S1, fault detection: using the detection module in the working system to detect the input process of the direct current input end 12 to the inverter main body 11 and the output process of the inverter main body 11 to the alternating current output end 13 respectively, and inputting the detected data signal into the control core synchronously; S2, priority judgment: judging the fault type in the inverter according to the signal input by the detection module, and controlling the execution mechanism to perform corresponding opening work according to the fault type; S3, fault analysis: when the fault type is arc fault, the DC side execution unit 5 starts to work and controls the circuit breaking component to disconnect the input of the DC input end 12 to the inverter main body 11, and according to the arc type detected by the arc detection unit 2, the DC discharge circuit in the DC side execution unit 5 is controlled to work correspondingly; when the fault type is island fault, the AC side execution unit 6 starts to work and disconnects the output of the inverter main body 11 to the AC output end 13; when the fault type is composite fault, the DC side execution unit 5 works preferentially and controls the circuit breaking component to disconnect the input of the DC input end 12 to the inverter main body 11, and then starts the DC discharge circuit, and after confirming that the DC voltage drops to a safety threshold, the AC side execution unit 6 controls the circuit breaking component to disconnect the output of the inverter main body 11 to the AC output end 13; S4, circuit breaking execution: when the circuit breaking component works, the driving mechanism controls the ejection mechanism to start, and the ejection mechanism further controls the disconnection mechanism to eject and disconnect.

[0049] In the scheme, the design of the working system is utilized to realize double detection of arc fault and island fault of the inverter main body 11, and according to different fault types, corresponding shutdown actions are performed, which effectively improves the safety and protection performance of the inverter main body 11.

[0050] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A fault detection device for a photovoltaic inverter, comprising a protective frame (1), characterized in that: It also includes a working system and a circuit breaker assembly, wherein the interior of the protective frame (1) is electrically connected in series with a DC input terminal (12), an inverter body (11), and an AC output terminal (13), wherein the DC input terminal (12) is arranged on the left side of the protective frame (1), the inverter body (11) is arranged in the middle section of the protective frame (1), and the AC output terminal (13) is arranged on the right side of the protective frame (1); The working system comprises a detection module, a control core and an actuator which are electrically connected in series in sequence, wherein the detection module comprises an arc detection unit (2) and an island detection unit (3) which are arranged on both sides of the upper part of the protection frame (1); the control core comprises a priority arbitration unit (4) which is arranged in the middle position of the protection frame (1); and the actuator comprises a DC side execution unit (5) and an AC side execution unit (6) which are arranged on both sides of the lower part of the priority arbitration unit (4); The disconnect assembly comprises a driving mechanism, a pop-up mechanism and a disconnect mechanism which are arranged on both sides of the inverter body (11) and are sequentially connected in series; the driving mechanism is signal-connected to a corresponding position actuator; and the disconnect mechanism is electrically connected to the corresponding position actuator.

2. A fault detection device for a photovoltaic inverter according to claim 1, characterized in that: The arc detection unit (2) is used to detect the DC signal of the DC input terminal (12). The arc detection unit (2) is provided with a high-frequency cable mutual inductor (21), a bandpass filter (22) and a logarithmic amplifier (23) connected in series in sequence, which is used to detect the high-frequency signal of the DC input terminal (12). The arc detection unit (2) is also provided with a Rogowski coil (24) and an integrator (25) connected in series in sequence, which is used to detect the current mutation of the DC input terminal (12). The output ends of the logarithmic amplifier (23) and the integrator (25) are connected in parallel with a comparator 1 (26); The island detection unit (3) is used to detect the AC signal of the AC output terminal (13). The island detection unit (3) is provided with a voltage transformer (31), a phase-locked loop (32), a frequency converter (33) and a second comparator (34) connected in series in sequence. The output terminal of the second comparator (34) and the output terminal of the first comparator (26) are connected in parallel to the priority arbitration unit (4).

3. A fault detection device for a photovoltaic inverter according to claim 1, characterized in that: The priority arbitration unit (4) completes arbitration judgment on the input signal. The priority arbitration unit (4) is provided with an AND gate chip (41), an OR gate chip (42) and a SiC driver chip (43) connected in series in sequence. The output end of the SiC driver chip (43) is connected in parallel with the DC side execution unit (5) and the AC side execution unit (6).

4. A fault detection device for a photovoltaic inverter according to claim 1, characterized in that: A circuit breaker component is provided inside the DC side execution unit (5) and the AC side execution unit (6), and a DC discharge circuit is provided inside the DC side execution unit (5). The DC discharge circuit is provided at the input end of the circuit breaker component in the DC side execution unit (5).

5. The fault detection device for a photovoltaic inverter according to claim 1, characterized in that: The driving mechanism includes a motor (7) whose start and stop are controlled by signals from a DC side execution unit (5) and an AC side execution unit (6); an output end of the motor (7) is fixedly connected to a screw rod (71); a threaded sleeve (72) is screwed on the outer contour of the screw rod (71); guide rails (73) are fixedly connected to the upper and lower sides of the outer contour of the threaded sleeve (72); a fixed cylinder (74) is sleeved on the outside of the threaded sleeve (72); a fixed seat (76) is fixedly connected to the inner wall of the bottom end of the protective frame (1) at the bottom end of the fixed cylinder (74); the motor (7) is fixedly connected to one side of the fixed cylinder (74); a sliding groove (75) adapted to the guide rail (73) is provided at a corresponding position on the surface of the fixed cylinder (74); and a connecting ring (77) is fixedly connected to the end of the threaded sleeve (72) away from the motor (7).

6. A fault detection device for a photovoltaic inverter according to claim 1, characterized in that: The pop-up mechanism includes a fixed frame (8) arranged on the inner wall of the bottom end of the protective frame (1), a transmission shaft (81) is horizontally passed through the top end of the fixed frame (8), one end of the transmission shaft (81) is fixedly connected to a second connecting ring (88), a connecting spring (89) is fixedly connected between the second connecting ring (88) and the first connecting ring (77), a middle section of the transmission shaft (81) is fixedly connected to a fixed ring (85), a movable frame (84) is passed through the middle section of the transmission shaft (81), the movable frame (84) is located inside the fixed frame (8), both sides of the bottom end of the movable frame (84) are provided with inclined grooves (86), and the inner contours of both sides of the movable frame (84) and the fixed ring (85) are fixedly connected to the second compression spring (87) sleeved on the outer contour of the transmission shaft (81); A compression spring (82) is provided in the middle section of the bottom end of the fixing frame (8), and a positioning pin (83) extending into the fixing frame (8) is fixedly connected to the top end of the compression spring (82), and the positioning pin (83) is abutted and clamped with the inclined groove (86).

7. A fault detection device for a photovoltaic inverter according to claim 1, characterized in that: The disconnect mechanism comprises a second fixing seat (9) arranged on the inner wall of the bottom end of the protection frame (1), the top end of the second fixing seat (9) is fixedly connected to a closed cylinder (91), one end of the inside of the closed cylinder (91) is fixedly connected to a static contact (93), a limiting cylinder (94) is provided on the inner wall of the closed cylinder (91) at one end of the static contact (93), a closed ring (92) is fixedly connected to the end of the inside of the closed cylinder (91) away from the static contact (93), a movable cylinder (95) is sleeved inside the closed cylinder (91), and the upper and lower surfaces of the movable cylinder (95) are provided with sealing rings. The closed loop (92) is adapted to a limiting groove (96), the interior of the movable cylinder (95) is fixedly connected with a moving contact (97), the end of the movable cylinder (95) away from the static contact (93) is fixedly connected to the end of the transmission shaft (81) away from the second connecting ring (88), the end of the moving contact (97) away from the transmission shaft (81) is engaged and clamped with the static contact (93), the inner wall of the movable cylinder (95) close to the static contact (93) is fixedly connected with a positioning cylinder (98), and the inner wall of the positioning cylinder (98) is fixedly connected with a positioning ring (99) adapted to the size of the static contact (93).

8. A method for using a photovoltaic inverter fault detection device, applicable to the photovoltaic inverter fault detection device according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Fault detection: using the detection module in the working system to detect the input process from the DC input terminal (12) to the inverter body (11) and the output process from the inverter body (11) to the AC output terminal (13), and synchronously input the detected data signals into the control core; S2. Priority determination: Based on the signal input from the detection module, the fault type in the inverter is determined, and the actuator is controlled to perform the corresponding disconnection work according to the fault type; S3. Fault analysis: When the fault type is an arc fault, the DC side execution unit (5) starts to work and controls the circuit breaker component to disconnect the input process of the DC input terminal (12) to the inverter main body (11), and controls the DC discharge circuit in the DC side execution unit (5) to work accordingly according to the arc type detected by the arc detection unit (2); when the fault type is an island fault, the AC side execution unit (6) starts to work and disconnects the output process of the inverter main body (11) to the AC output terminal (13); when the fault type is a composite fault, the DC side execution unit (5) works first and controls the circuit breaker component to disconnect the input process of the DC input terminal (12) to the inverter main body (11), and then starts the DC discharge circuit. After confirming that the DC voltage drops to a safety threshold, the AC side execution unit (6) controls the circuit breaker component to disconnect the output process of the inverter main body (11) to the AC output terminal (13); S4. Circuit breaking execution: When the circuit breaking assembly is working, the driving mechanism controls the pop-up mechanism to start, and the pop-up mechanism further controls the disconnection mechanism to pop out and disconnect.

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