JP4463936B2 - Solar panel ground fault detector - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a ground fault detection device for a photovoltaic power generation panel.
[0002]
The number of installed solar power panels is increasing rapidly from the viewpoint of environmental and energy problems, but unlike AC power lines, protection devices against ground faults are not so popular.
[0003]
However, there is a possibility of an accident due to a ground fault of the photovoltaic power generation panel as follows. Solar power generation panels are installed for a long period of time in an exposed state due to the principle of nature, so there is a high possibility of damage or insulation failure due to wind and rain, earthquakes, etc. Since they are installed in series-parallel connection, damage and insulation failure may occur not only at the voltage output terminals and connecting wires, but also at the connection points between panels, indicating that damage or insulation failure has occurred. If left unattended and a ground fault is reached, depending on the voltage, there is a risk of a fire from a spark due to a short circuit or electric leakage, or a disaster due to an electric shock.
[0004]
Therefore, there is a demand for a device capable of detecting a ground fault early in order to detect a ground fault due to damage or insulation failure of a solar power generation panel or to cut off an electric circuit supplied from the solar panel. Examples of such a ground fault detection device for a DC electric circuit can be found in Japanese Patent Application No. 1-319855 (Japanese Patent Laid-Open No. 3-179272) and Japanese Patent Application No. 5-318853 (Japanese Patent Laid-Open No. 7-177646). Two resistance circuits are connected to the PN voltage side line of the DC circuit and G (ground: earth), and the voltage between the electrodes in the two states, the connected resistance value, the current flowing through the circuit, etc. The ground fault resistance value and ground fault point are calculated from the measurable values.
[0005]
【Task】
If the ground fault detection device as described above is used, it is possible to obtain the ground fault resistance value and the ground fault point. However, a solar panel such as a house is connected between the panel and a load device by a DC-AC converter ( When a power conditioner is used as an alternative or auxiliary power source for commercial (alternating current) power, there are the following problems.
[0006]
Residential commercial power uses a single-phase three-wire power transmission system, and is supplied from two voltage lines and a neutral line grounded to the ground. On the other hand, the power conditioner converts the input voltage (DC) supplied from the photovoltaic power generation panel into single-phase, three-wire AC (the AC voltage of the two voltage lines is equal to the neutral line). The output voltage is connected to a single-phase three-wire circuit of commercial power. The conversion from DC to AC in such a power conditioner is performed by changing the voltage of the G pole (the pole connected to the neutral line of the commercial circuit) with respect to the two PN pole DC voltage lines. The voltage of the two AC output lines is apparently AC, and the G pole is connected to the ground via a commercial power circuit, so that the power conditioner is in operation. The potential between the PN and G poles used by the previous DC ground fault detector for calculation is always changing, which is inconvenient for measuring ground fault resistance and ground fault point.
[0007]
In view of the above problems, the present invention relates to the ground fault of the photovoltaic power generation panel of the photovoltaic power generation system including the photovoltaic power generation panel and the power conditioner that is connected to the alternating current circuit that is converted from direct current to alternating current and grounded. An object of the present invention is to obtain a device capable of reliably performing detection.
[0008]
[Means for Solving the Problems]
Accordingly, in the present invention, in claim 1, a photovoltaic power generation panel of a photovoltaic power generation system comprising a photovoltaic power generation panel and a power conditioner that is connected to an alternating current circuit in which a direct current is converted into an alternating current and one line is grounded. The ground fault detection device, which is connected between the voltage side electric circuit of the power generation output line PN connecting the photovoltaic power generation panel and the power conditioner and connected to the ground,
It is driven by a power supply voltage lower than the operating voltage of the power conditioner,
The ground fault detection device includes
And a control unit which acts on the ground fault detector and the ground fault detector and the operation detecting portion of the power conditioner and the display output unit is provided,
The operation detector of the inverter is
By detecting the voltage between the power generation output lines of the photovoltaic power generation panel (the DC side input voltage terminal of the power conditioner) , whether or not the voltage is a voltage at which the power conditioner operates, or the power generation output line and the ground If the detected voltage fluctuates more than the specified value,
Determine that the inverter is in operation,
When it is determined by the operation detection unit that the inverter is operating, the control unit
Even if the ground fault detector detects a ground fault,
When the ground fault detection output of the ground fault detection unit is limited so that the output indicating that a ground fault has occurred is not output to the display output unit, and it is determined that the inverter is not operating, The present invention provides a ground fault detection device for a photovoltaic power generation panel, characterized by outputting and displaying information detected by a fault.
[0009]
As a result, even if part out of the ground fault has not occurred the detection output of the ground fault, if the power conditioner is running, because it limits the output that has been ground, is an error in the ground fault detection output It is possible to obtain a ground fault detection apparatus capable of providing accurate ground fault information without generating an output when there is a possibility . Further, by detecting the variation of the ground potential to the power output line of the solar panels (input voltage terminal of the DC side of the power conditioner) to determine the operation of the power conditioner, the operation information from the power conditioner itself There is no need to get.
[0010]
Claim 2 is a ground fault detection device for a photovoltaic power generation panel of a photovoltaic power generation system comprising a photovoltaic power generation panel and a power conditioner connected to an alternating current circuit in which a direct current is converted into alternating current and one line is grounded. The ground fault detection device is connected between the voltage side electric circuit of the power generation output line PN connecting the photovoltaic power generation panel and the power conditioner and connected to the ground.
It is driven by a power supply voltage lower than the operating voltage of the power conditioner,
The ground fault detection device includes
And a control unit which acts on the ground fault detector and the ground fault detector and the operation detecting portion of the power conditioner and the display output unit is provided,
The operation detector of the inverter is
By detecting the voltage between the power generation output lines of the photovoltaic power generation panel (the DC side input voltage terminal of the power conditioner) , whether or not the voltage is a voltage at which the power conditioner operates, or the power generation output line and the ground If the detected voltage fluctuates more than the specified value,
Determine that the inverter is in operation,
When it is determined by the operation detection unit that the power conditioner is operating, the control unit adds a limit to the operation of the ground fault detection unit so as to stop the detection operation of the ground fault detection unit , If the power conditioner is determined not running is obtained by providing a ground fault sensing device of the solar panels, wherein also be output from display information issued ground-fault.
[0011]
As a result, when the inverter is in operation, the ground fault detection unit does not operate, so if there is a possibility that the ground fault detection output has an error, it is not operated to provide accurate ground fault information. It is possible to obtain a ground fault detection device capable of doing this. Further, by detecting the variation of the ground potential to the power output line of the solar panels (input voltage terminal of the DC side of the power conditioner) to determine the operation of the power conditioner, the operation information from the power conditioner itself There is no need to get.
[0018]
[Explanation of Examples]
FIG. 1 is a diagram showing a connection relationship between a photovoltaic power generation system and a ground fault detection device of the present invention. In FIG. 1, reference numeral 1 denotes a photovoltaic power generation panel, which outputs a DC voltage between 2 and 3, and 2 is a P pole (+ pole) and 3 is an N pole (-pole). Reference numeral 4 denotes a ground fault detection device connected to the lines 2 and 3. G is a (ground) pole that is drawn from the ground fault detection device and connected to the ground. A power conditioner 5 converts the DC voltage supplied from 2 and 3 into an AC voltage connected to the commercial power circuit side of 6, 7, and 8 and outputs the AC voltage. The power conditioner 5 operates when the voltage between 2 and 3 exceeds a certain value, and when it is less than the certain value, the output of the photovoltaic power generation panel is judged to be insufficient and does not operate. The ground fault detection device 4 may be set to operate sufficiently with a power supply voltage lower than the voltage at which the power conditioner 5 operates, and may receive power supply from the electric wires 2 and 3, or from a separate battery or commercial power supply. Power may be supplied.
[0019]
6, 7, 8 are electric circuits connected to the commercial electric circuits 12, 13, 14 through circuit breakers and disconnectors 11, 6 is an L1 phase voltage line, 7 is a neutral line, and 8 is an L2 phase voltage. Is a line. Reference numerals 9 and 10 denote load devices (for example, home appliances) that work with an AC voltage connected to the electric circuit. Reference numeral 15 denotes a power transformer for single-phase three-wire distribution on the commercial power line side, and a neutral line 13 is a place where the power transformer is installed, and is connected (grounded) to the ground like E. The power supply of the loads 9 and 10 is supplied from the photovoltaic power generation panel side when the power generation amount of the photovoltaic power generation panel is sufficient, and when the power generation amount of the photovoltaic power generation panel is insufficient or insufficient, It is supplied from the transformer 15 completely or complementarily.
[0020]
2 and 3 are configuration diagrams of an embodiment of the ground fault detection apparatus according to the present invention. In FIG. 2, the ground fault detection device 4 includes a ground fault detection unit 41, a power conditioner operation detection unit 42, a control unit 43, and a display output unit 44. The ground fault detector 41 is connected to the P pole, N pole, and G (ground) of the DC circuit, and the above-mentioned Japanese Patent Application Nos. 1-319855 (Japanese Patent Laid-Open No. 3-179272) and Japanese Patent Application No. 5-318853 (special Japanese Patent Application) As described in Kaihei 7-177646), a resistance circuit in two states is connected to three poles of P, N, and G, and the voltage between the poles in the two connection states, the connected resistance value, and the circuit When a ground fault is recognized by a method of calculating the ground fault resistance value or ground fault point from the value of the current flowing through the ground, an output is generated. Reference numeral 42 denotes a power conditioner operation detection unit which may receive operation information directly from the power conditioner 5 or may determine operation by the method shown in FIGS. Reference numeral 43 denotes a control unit. When there is a determination output indicating that the power conditioner is operating from the power conditioner operation detection unit 42, an output indicating that a ground fault has occurred from the ground fault detection unit 41 is output to the display output unit 44. To the display output unit 44 with a restriction that there is a doubt that it is really grounded because the inverter is in operation. Output.
[0021]
In FIG. 3, 41 is a ground fault detection unit, and 42 is a power conditioner operation detection unit, which is the same as that shown in FIG. Reference numeral 45 denotes a control unit which controls to stop the detection operation of the ground fault detection unit 41 when there is a determination output from the power conditioner operation detection unit 42 that the power conditioner 5 is operating. When the ground fault detection unit 41 is operating and a ground fault is detected, ground fault information is output to the display output unit 44.
[0022]
As described above, the ground fault detection unit 41 described above connects the resistance circuit in two states to the three poles P, N, and G, and the voltage between the electrodes in the two connection states, the connected resistance value, the circuit The ground fault resistance value and ground fault point are calculated from the value of the current flowing through the ground, and it has the ability to determine even a weak ground fault such as a ground fault resistance value of 100 kΩ. It is an effective method. Among the elements used in the above calculation, the voltage between the electrodes is a very important element. Therefore, if the voltage between P, N, and G varies due to an external factor during measurement, accurate detection cannot be performed.
[0023]
However, when using a power conditioner in the case where the direct current is converted into an alternating current as in the photovoltaic power generation system of FIG. 1, the power conditioner function described above is used for commercial use with respect to the P and N poles. Because the potential of the N pole on the side fluctuates and the N pole is grounded like E at the power transformer installation point, the potential of the G pole also fluctuates and accurate detection is possible when the power conditioner is operating 2 and 3, the method shown in FIGS. 2 and 3 includes a power conditioner operation detection unit 42. When the power conditioner is operating, the control units 43 and 45 limit the output of the ground fault detection unit 41. Alternatively, the ground fault detection unit 41 is not operated, and the information on the detection of the ground fault is displayed and output when the inverter is not operating, so that accurate detection is possible. That.
[0024]
4 and 5 are configuration examples of the power conditioner operation detection unit 42. FIG.
In the example of FIG. 4, the voltage detection unit 421 detects the voltage between the P and N poles, and the determination unit 422 determines whether the voltage is a voltage at which the power conditioner 5 operates. It is determined that the conditioner is operating.
[0025]
In the example of FIG. 5, the voltage detection unit 423 detects the voltage between PG and the voltage between GN, and when the detected voltage fluctuates more than a specified value, the determination unit 424 operates the power conditioner. It is determined that That is, in both the examples shown in FIG. 4 and FIG. 5, whether or not the inverter is operating directly from the power conditioner is determined only by the voltage between the P and N poles without separately drawing an electric wire or the like. The operation of the inverter can be judged simply by connecting a detection line between the N poles, and there are no restrictions on the installation location.
[0026]
【The invention's effect】
As described above, according to the present invention, the photovoltaic power generation panel of the photovoltaic power generation system including the photovoltaic power generation panel and the power conditioner connected to the alternating current circuit that is grounded by converting the direct current to alternating current is connected. In the ground fault detection device, there is an effect that a device capable of performing detection reliably can be obtained.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a solar power generation system provided with a ground fault detection device according to the present invention. FIG. 2 is a configuration diagram of a ground fault detection device according to claim 1 of the present invention. FIG. 4 is a block diagram of the power conditioner of the ground fault detection device of claim 3 according to the present invention. FIG. 5 is a block diagram of the power conditioner of the ground fault detection device of claim 4 according to the present invention. Figure [Explanation of symbols]
1 ·· Solar power generation panel 2 ·· P pole wire 3 ·· N pole wire 4 ·· Ground fault detection device 5 ·· Power conditioner 6 ·· L1 phase voltage wire 7 ·· Neutral wire 8 ·· L2 phase Voltage line 9 ・ ・ Load A
10 .. Load B
11 ·· Circuit breaker 15 · · Power transformer 41 · · Ground fault detector 42 · · Power conditioner operation detector 43 · · Control unit 44 · · Display output unit 45 · · Control unit 421 · · Voltage detector 422・ ・ Determining unit 423 ・ ・ Voltage fluctuation detecting unit 424 ・ ・ Determining unit

Claims (2)

Photovoltaics clear distinction converts the DC voltage generator with photovoltaic panels and the solar panels to AC voltage comprising a power conditioner that is output to the single-phase three-wire AC circuit that is grounded A ground fault detection device for a photovoltaic panel of a system,
The ground fault detection device is connected between the voltage side electric circuit of the power generation output line PN connecting the photovoltaic power generation panel and the power conditioner and connected to the ground.
It is driven by a power supply voltage lower than the operating voltage of the power conditioner,
The ground fault detection device includes
And a control unit which acts on the ground fault detector and the ground fault detector and the operation detecting portion of the power conditioner and the display output unit is provided,
The operation detector of the inverter is
By detecting the voltage between the power generation output lines of the photovoltaic power generation panel (the DC side input voltage terminal of the power conditioner) , whether or not the voltage is a voltage at which the power conditioner operates, or the power generation output line and the ground If the detected voltage fluctuates more than the specified value,
Determine that the inverter is in operation,
When it is determined by the operation detection unit that the inverter is operating, the control unit
Even if the ground fault detector detects a ground fault,
When the ground fault detection output of the ground fault detection unit is limited so that the output indicating that a ground fault has occurred is not output to the display output unit, and it is determined that the inverter is not operating, A ground fault detection device for a photovoltaic power generation panel, characterized by outputting and displaying information detected by a fault. Photovoltaics clear distinction converts the DC voltage generator with photovoltaic panels and the solar panels to AC voltage comprising a power conditioner that is output to the single-phase three-wire AC circuit that is grounded A ground fault detection device for a photovoltaic panel of a system,
The ground fault detection device is connected between the voltage side electric circuit of the power generation output line PN connecting the photovoltaic power generation panel and the power conditioner and connected to the ground.
It is driven by a power supply voltage lower than the operating voltage of the power conditioner,
The ground fault detection device includes
And a control unit which acts on the ground fault detector and the ground fault detector and the operation detecting portion of the power conditioner and the display output unit is provided,
The operation detector of the inverter is
By detecting the voltage between the power generation output lines of the photovoltaic power generation panel (the DC side input voltage terminal of the power conditioner) , whether or not the voltage is a voltage at which the power conditioner operates, or the power generation output line and the ground If the detected voltage fluctuates more than the specified value,
Determine that the inverter is in operation,
When it is determined by the operation detection unit that the power conditioner is operating, the control unit adds a limit to the operation of the ground fault detection unit so as to stop the detection operation of the ground fault detection unit , power if the conditioner is determined to be not running, ground fault sensing device of solar panels which is characterized that you output display the information out ground-fault.

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