JP2011007765A - Arc detection means, and control means and communication means both employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection means for detecting a generated arc more accurately.SOLUTION: The arc detection means includes: a voltage detection means for measuring the value of a voltage between an input-side wire extending to a terminal block and an output-side wire extending from the terminal block; a current detection means for measuring the value of a current flowing through the output-side wire extending from the terminal block; and a detection circuit capable of simultaneously detecting a change in value of the voltage measured by the voltage detection means and a change in value of the current measured by the current detection means.

Description

  The present invention relates to an arc detection means, a control means using the same, and a communication means.

  A conventional power supply device will be described with reference to the drawings based on an example of a photovoltaic power generation system.

  For example, FIG. 4 is a schematic configuration diagram of a conventional photovoltaic power generation system.

  2. Description of the Related Art In recent years, a grid interconnection system that converts an output from a solar battery power source 2 into alternating current by a power converter 1 and is linked to a commercial power grid has been put into practical use. In this grid interconnection system, DC power generated by the solar battery power source 2 is converted into, for example, 200 V of AC power by the power conversion device 1 and connected to the commercial power grid 11.

  The solar cell power source 2 has a configuration in which a plurality of solar cell modules are connected in series, and an output of several hundred V (100 to 300 V in general household use) is input to the power converter 1. Here, the power converter 1 and the solar battery power source 2 are connected by a cable or the like, and on the power converter 1 side, the terminal block and the cable are generally fixed by screws.

  In terminal blocks for electrical connection, not limited to photovoltaic power generation systems, if the connection state is incomplete due to forgetting screw tightening of construction work or process work, an arc is generated, causing a short circuit or disconnection There was a thing.

  In order to detect these abnormal conditions, traditionally, a temperature element such as a thermal fuse has been placed on the terminal block to detect heat generation around the terminal block and stop the equipment or shut off the DC breaker. Are known.

  However, in the conventional method, it is necessary to strictly limit the arrangement position of the temperature element in order to detect the temperature accurately, or when the temperature suddenly rises, the temperature element cannot follow and the damage increases. There was a problem.

  In view of this, for example, a method has been proposed in which frequency distribution measurement of the amount of fluctuation of the current detected within a predetermined time is performed, and tracking detection is performed from the ratio (see, for example, Patent Document 1).

JP 2001-103657 A

  However, in Patent Document 1, the voltage is not monitored, and only the arc is not necessarily detected. This is because, when there is an electrical contact such as a relay in the circuit of the power conversion device, the electrical noise generated when the contact is changed is very similar to an arc.

In addition, in order not to be confused with such other electrical noise, if it is determined that multiple arcs will not occur, a single arc will be applied to the terminal block over a long period of time. There was a problem that the damage to the terminal block was accumulated and eventually a short circuit between the electric circuits was reached.

  Moreover, when it is going to identify by the magnitude | size etc. of arc discharge, it changes with the electric power generation of the solar cell power supply 2 at that time, and the state (looseness and contact speed) of the contact point which arc discharge generate | occur | produces in a terminal block. Therefore, it is difficult to standardize and compare things such as current magnitude and voltage change.

  In order to solve the above problems, the arc detection means of the present invention comprises a voltage detection means for measuring a voltage value between the input side wiring to the terminal block and the output side wiring from the terminal block, and the terminal block A current detection unit that measures a current value of the output-side wiring; and a detection circuit that can simultaneously detect a variation in the voltage value of the voltage detection unit and a variation in the current value of the current detection unit.

  Furthermore, the arc detection means of the present invention includes a first stage in which the voltage value increases from the operating voltage value and the current value decreases from the operating current value, and the current within a predetermined time after the first stage. An output signal is generated by detecting a second stage whose value increases above the operating current.

  Further, in the arc detection means of the present invention, the predetermined time is 0 to 300 μsec.

  Further, in the arc detection means of the present invention, the time of the first stage is 50 to 500 μsec.

  Further, in the arc detection means of the present invention, the time of the second stage is 200 to 900 μsec.

  Further, the control means of the present invention has a control circuit for stopping the power supply to the input side wiring when the output signal emitted from the detection means is inputted.

  Furthermore, the communication means of the present invention notifies that the power supply has been stopped by inputting an output signal emitted from the detection means.

  According to the arc detection means of the present invention, the voltage detection means for measuring the voltage value between the input side wiring to the terminal block and the output side wiring from the terminal block, the current value of the output side wiring from the terminal block Current detection means that measures the fluctuation of the voltage value of the voltage detection means and the detection circuit that can simultaneously detect the fluctuation of the current value of the current detection means. Since it is possible to distinguish between electric noise and the like generated at the time of contact change and an arc in the terminal block, the detection accuracy can be improved.

  Thereby, there exists a malfunction in the connection point from the solar cell power supply 2, and even when an arc generation | occurrence | production arises, it has an effect of stopping a power supply device appropriately.

It is a schematic diagram for demonstrating one Embodiment of the detection means of the arc generation in the input side terminal of the power supply device of the solar cell of this invention, and a control means using the same. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram of the terminal part explaining one Embodiment of the detection means of the arc generation in the input side terminal of the power supply device of the solar cell of this invention, and a control means using the same, (a) is sectional side view, (b) ) Is a top view of the terminal block. It is a figure which shows an example of the waveform of the electric current and voltage detected at the time of arc generation for demonstrating one Embodiment of the detection means of the arc generation in the input side terminal of the power supply device of the solar cell of this invention, and the control means using the same. is there. It is a schematic diagram of the conventional solar power generation system. It is a schematic diagram of the noise waveform in the conventional voltage detection means and current detection means, (a) is a waveform when noise from the motor is applied, (b) is a waveform when the electric circuit to the load is interrupted. . It is a schematic diagram of the noise waveform in the voltage detection means and the current detection means of one embodiment of the present invention, (a) is a waveform when noise from the motor is applied, (b) is a circuit that cuts off the electric path to the load Waveform of the case. It is a schematic diagram for demonstrating the control means of one Embodiment of this invention.

  The arc generation detecting means of the present invention includes voltage detecting means for measuring a voltage value between an input side wiring to the terminal block and an output side wiring from the terminal block, and a current of the output side wiring from the terminal block. A current detection unit for measuring a value; and a detection circuit capable of simultaneously detecting a variation in the voltage value of the voltage detection unit and a variation in the current value of the current detection unit.

  By making it possible to simultaneously detect the fluctuation of the voltage value of the voltage detection means and the fluctuation of the current value of the current detection means, it becomes possible to manage the behavior of the current and voltage, and the relay of the relay in the circuit of the power conversion device Since it is possible to discriminate between electric noise generated at the time of contact change and an arc, detection accuracy can be improved.

  As a result, there is a problem in the connection point from the DC power supply, and even when there is a risk of heat generation or ignition due to an arc or the like, the power supply device is appropriately stopped.

  Hereinafter, embodiments of the present invention will be described. First, the wiring positions of the voltage detection means and the current detection means and the relationship with various noises will be described. FIG. 5 is a schematic diagram of noise waveforms in the conventional voltage detection means and current detection means. FIG. 6 is a schematic diagram of noise waveforms in the voltage detection means and current detection means according to the embodiment of the present invention. Is a voltage waveform. Here, while the horizontal scale in the graph of FIG. 3 is 1000 μsec, since the noise generation time is about 10 μsec, which is shorter than the arc generation time, the horizontal scale of the graphs in FIGS. 10 μsec, which is approximately 1/100 scale.

  First, FIG. 5 is measured between the positive pole and the negative pole of the DC power supply. At this time, FIG. 5A shows a waveform when noise from the motor is applied to the current line, and the current and voltage show substantially the same waveform. Although the current waveform increases or decreases on the plus side, the voltage tends to decrease if the power supply capacity is not sufficient. FIG. 5B shows a waveform when the electric path to the load is interrupted, and the current and voltage show substantially the same waveform. In addition, since a load cannot be cut off instantaneously in an electric motor or the like, showering noise tends to occur depending on conditions. As described above, in the voltage detection means and the current detection means measured between the positive pole and the negative pole of the conventional DC power source as shown in FIG. 5, the behaviors of the current and voltage are the same, and only unique detection can be performed. Therefore, noise and arc cannot be distinguished.

On the other hand, according to the embodiment of the present invention, the voltage detection means for measuring the voltage value between the input side wiring and the output side wiring across the terminal block is arranged, and the current of the output side wiring from the terminal block is arranged. Since the current detecting means for measuring the value is arranged, even when measured in the same situation as in FIGS. 5A and 5B, as shown in FIGS. 6A and 6B, respectively. There is no change in voltage. That is, according to the present embodiment, it is possible to prevent erroneous recognition of the noise waveform and the arc waveform and to confirm the occurrence of the arc more accurately.

  Based on these, an embodiment of the arc detection means of the present invention, and control means and communication means using the same will be described below with reference to the drawings.

  FIG. 1 is a schematic diagram of an embodiment of an arc detection means and a control means using the same according to the present invention. The power converter 1 includes a terminal block 3 to which DC power of the solar battery power source 2 is input, a voltage detection means 4 (IN side voltage detection terminal), an input filter circuit 5 connected to the terminal block 3, and an input filter circuit 5. A power conversion circuit 6 that converts the passed DC power into AC power, a control circuit 7 that performs control such as switching for power conversion of the power conversion circuit 6, in particular, a determination unit 14 that determines whether or not it is an arc, and a power conversion circuit And an output filter circuit 8 for connecting the output of 6 to the commercial power system 11, a voltage detection means 9 (OUT side voltage detection terminal) and a current detection means 10 arranged at the front stage or the rear stage of the input filter circuit 5. .

  The input filter circuit 5 and the output filter circuit 8 have a function of removing noise components by a filter constituted by a capacitor and a choke coil and protecting the power supply device from an external surge by a varistor or the like.

  The power conversion circuit 6 includes a reactor, a semiconductor switching element, a diode, a capacitor, and the like, and controls the semiconductor switch element with a PWM signal output from the control circuit 7 to convert the DC power into a sine wave commercial AC waveform. It has a function to convert.

  Further, the power converter 1 is controlled from the voltage and current information of the voltage detection means 4 (IN side voltage detection terminal), voltage detection means 9 (OUT side voltage detection terminal) and current detection means 10.

  FIG. 2 shows the vicinity of the terminal block 3 of the power converter 1. For example, when the screw tightening in the terminal block 3 is not normal, the screw or terminal portion of the terminal block 3 is kept conductive by light contact. The contact state is unstable and an arc is involved.

  FIG. 3 shows a waveform at the time of arc occurrence, (a) shows the voltage across the voltage detection means at the time of arc occurrence, and (b) shows the current in the same path.

  Here, the voltage detection means 4 (IN side voltage detection terminal) and the voltage detection means 9 (OUT side voltage detection terminal) measure the voltage between the front stage and the rear stage of the terminal block 3, and the control circuit 7, The determination unit 14 performs sampling and derives a potential difference between both terminals. The current detection means 10 also acquires the value of the current flowing through the terminal block 3 and performs sampling by the control circuit 7 and the determination unit 14.

  In the operation at the time of actual arc generation, (1) when the contact is maintained at the screw portion of the terminal block 3, (2) when the contact portion is released by some stress (arc generation region), (3 3) When returning to the contact state again, the transition is made in the order of and the waveform shown in FIG. 3 is sampled.

When attention is paid to the state (2), the voltage detecting means 4 (IN side voltage detecting terminal) and the voltage detecting means 9 (OUT side voltage) which are almost 0 in the region (1) when the contact portion is opened. The potential difference between the detection terminals) fluctuates greatly. This is because the operating point moves to the open-circuit voltage point in the no-load state due to the characteristics of the solar cell. Further, from the current waveform obtained by the current detection means 10, the current value once decreases with the opening of the contact portion, but since the potential difference occurs in the open portion as described above, the current flows rapidly as an arc. I understand that.

  That is, in the control circuit 7, both conditions of an increase in potential difference between the voltage detection means 4 (IN side voltage detection terminal) and the voltage detection means 9 (OUT side voltage detection terminal) and current oscillation fluctuation of the current detection means 10. Thus, it is possible to determine that an arc has occurred in the terminal portion on the input side, and to take appropriate measures such as stopping the operation of the power conversion device 1, displaying an error, and warning.

  In addition, this invention is not limited to the above-mentioned form, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.

  Furthermore, the arc detection means according to an embodiment of the present invention includes a first stage in which the voltage value increases from the operating voltage value and the current value decreases from the operating current value, and a predetermined time after the first stage. It is preferable that an output signal is generated by detecting a second stage in which the current value increases above the operating current.

  By defining the relationship between the current and voltage behavior, it is possible to further distinguish between electrical noise and arcs generated when the relay contacts in the circuit of the power converter 1 are changed. Accuracy can be increased.

  Furthermore, in the arc detection means according to the embodiment of the present invention, the predetermined time is preferably 0 to 300 μsec.

  By defining such a threshold for the predetermined time, electrical noise and arc generated when the contact of the relay in the circuit of the power supply (power converter) is changed between the first stage and the second stage. Since it is possible to make the setting easier to identify from the time axis in the predetermined time, the detection accuracy can be improved.

  Furthermore, in the arc detection means according to the embodiment of the present invention, the time of the first stage is preferably 50 to 500 μsec.

  By defining such a first-stage threshold value, electric noise and arc generated at the time of relay contact change in the circuit of the power supply device (power converter), from the time axis in the first-stage voltage, Furthermore, since it can set so that it can identify easily, detection accuracy can be improved.

  Furthermore, the arc detection means according to the embodiment of the present invention preferably has a second stage time of 200 to 900 μsec.

  By defining such a second-stage threshold value, electric noise and arc generated at the time of relay contact change in the circuit of the power supply device (power conversion device), from the time axis in the second-stage current, Furthermore, since it can set so that it can identify easily, detection accuracy can be improved.

  Furthermore, it is preferable that the control unit according to the embodiment of the present invention includes a control circuit that stops the power supply to the input-side wiring when the output signal generated from the detection unit is input.

  As a result, there is a problem in the connection point from the DC power supply, and the power supply device is appropriately stopped even when an arc occurs.

  Further, as another embodiment of the control means, it may be a control means for performing control so as to repair a defect occurring in the terminal block when an arc is generated. Specifically, for example, as shown in FIG. 2, when the crimp terminal 3c is not in contact with the circuit board 3b, the crimp terminal 3c is restored to a normal state by the control means.

In this embodiment, as shown in FIG. 7, in the structure of the terminal block 3, the connection between the electric circuit board 3b and the crimp terminal 3c is maintained by magnetic force as necessary. In the present embodiment, the terminal block 3 has a structure in which the circuit board 3b and the crimp terminal 3c are sandwiched between the ring-shaped magnetic body 3d and the electromagnet 3e. When the crimp terminal 3c is not in contact with the circuit board 3b, the control means of this embodiment receives an output signal emitted from the detection means and recognizes that an arc has occurred. Next, the control means operates the electromagnet 3e so that the electric circuit board 3b and the crimp terminal 3c come into contact with the magnetic body 3d. According to such a control means, it is possible to detect that the electrical circuit board 3b and the crimp terminal 3c are not in contact with each other by the generation of an arc, and accordingly, the crimp terminal 3c can be returned to a normal state. The power supply can be operated safely until the maintenance engineer is dispatched and the root cause of the arc is repaired.

  As such a control means, an electric circuit in which electric power is supplied to the electromagnet when the electric signal or the contact is turned on and off by the arc detection means is suitable. Specifically, when it is determined by the arc generation detecting means of the present invention that an arc is generated, it is taken out as an electric signal and indirectly driven by driving the electromagnet 3e directly or by driving a relay or a semiconductor element. Electric power is supplied to generate a magnetic force in the electromagnet 3e. Thereby, the crimp terminal 3c can be brought into contact with the circuit board 3b by the electromagnet 3e and the magnetic body 3d. The magnetic body 3d is preferably a ferromagnetic washer such as iron or an alloy containing iron, and the surface of the washer may be subjected to rust prevention treatment such as gold plating or chrome plating. Also, non-ferrous metals that are not easily affected by magnetic force, such as stainless steel, can be applied by plating the surface with nickel or a cobalt alloy. Moreover, the electromagnet 3e can use what gave the directivity to magnetic flux, for example by winding a thin copper wire around an iron core.

  In this embodiment, the connection between the electric circuit board 3b and the crimp terminal 3c is maintained by the magnetic body and the electromagnet. However, as long as the connection between the electric circuit board 3b and the crimp terminal 3c can be maintained, It is not limited to such a form.

  Furthermore, it is preferable that the output unit according to the embodiment of the present invention includes a communication unit for notifying that the power supply has been stopped by inputting the output signal generated from the detection unit.

  As a result, there is a problem in the connection point from the DC power supply, and even when an arc is generated, the stop is appropriately notified.

1: Power conversion device 2: Solar cell power source 3: Terminal block 3a: Terminal block insulating part 3b: Electrical circuit board 3c: Crimp terminal 3d: Magnetic body 3e: Electromagnet 4: Voltage detection means (IN side voltage detection terminal)
5: Input filter circuit 6: Power conversion circuit 7: Control circuit 8: Output filter circuit 9: Voltage detection means (OUT side voltage detection terminal)
10: Current detection means 11: Commercial power system 14: Control circuit determination unit 17: Control circuit

Claims (7)

Voltage detecting means for measuring a voltage value between the input side wiring to the terminal block and the output side wiring from the terminal block;
Current detection means for measuring the current value of the output side wiring from the terminal block;
An arc detection means comprising: a detection circuit capable of simultaneously detecting a fluctuation in voltage value of the voltage detection means and a fluctuation in current value of the current detection means. A first stage in which the voltage value increases from the operating voltage value, the current value decreases from the operating current value, and the current value increases from the operating current value within a predetermined time after the first stage. The arc detecting means according to claim 1, wherein an output signal is generated by detecting the second stage. The arc detection means according to claim 2, wherein the predetermined time is 0 to 300 μsec. The arc detection means according to claim 2 or 3, wherein the time of the first stage is 50 to 500 µsec. The arc detection means according to claim 2 or 3, wherein the second stage time is 200 to 900 µsec. Control means for stopping power supply to the input-side wiring when an output signal emitted from the arc detection means according to any one of claims 1 to 5 is input. 6. A communication means for notifying that the power supply has been stopped by receiving an output signal generated from the arc detection means according to any one of claims 1 to 5.

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