JP2001298850A - Ground detector of photovoltaic power generation panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ground detector which can detect surely a ground in a photovoltaic power generation panel of a photovoltaic power generation system composed of the photovoltaic power generation panel and a power conditioner which converts a DC power into an AC power and is connected to an AC power route whose one line is earthed. SOLUTION: A ground detector of a photovoltaic power generation panel of a photovoltaic power generation system composed of the photovoltaic power generation panel and a power conditioner, which converts a DC power into an AC power and is connected to an AC power route whose one line is earthed, comprises a ground detection unit, a power conditioner operation detection unit and a control unit. When the operation detection unit detects the operation of the power conditioner, the control unit restricts the ground detection output of the ground detection unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ground fault detecting device for a photovoltaic power generation panel.

[0002] The number of installed solar power panels is rapidly increasing from the viewpoint of environmental problems and energy problems. However, unlike AC power lines, protective devices for ground faults are not widely used at present.

[0003] However, there is a possibility of an accident due to a ground fault of the photovoltaic power generation panel as follows. Since solar panels are installed outdoors for a long period of time due to their principle nature, there is a high possibility that damage or insulation failure will occur due to wind, rain, earthquake, etc. Because they are connected in series and parallel, damage and insulation failure may occur not only at the voltage output terminals and connection wires, but also at the connection points between panels. If left unattended and a ground fault occurs, depending on the voltage, there is a danger of a fire resulting from a spark due to a short circuit or a short circuit, or a disaster due to an electric shock.

Therefore, there is a need for a device capable of early detection of a ground fault due to damage or insulation failure of a photovoltaic power generation panel or detection of a ground fault in order to cut off an electric circuit supplied from the photovoltaic panel. Japanese Patent Application No. 1-319855 (Japanese Unexamined Patent Application Publication No. 3-179) discloses such a ground fault detecting device for a DC circuit.
272) and Japanese Patent Application No. 5-318853 (Japanese Unexamined Patent Application Publication No. 7-1).
No. 77646) and the PN
A two-state resistor circuit is connected to the voltage-side line of G and the three poles of G (earth: ground), and measurable values such as the voltage between the poles in the two states, the connected resistance value, and the current flowing in the circuit Then, the ground fault resistance value and the ground fault point are calculated and obtained.

[0005]

It is possible to obtain a ground fault resistance value and a ground fault point by using a ground fault detecting device as described above. When a converter (power conditioner) is used as a substitute for a commercial (AC) power supply or as an auxiliary power supply, there are the following problems.

A commercial power supply for a house uses a single-phase three-wire power transmission system, and is supplied from two voltage wires and a neutral wire 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 (AC in which the voltage of two voltage lines is equal to the neutral line). The output voltage is connected to a single-phase three-wire circuit of a commercial power supply. The conversion from DC to AC of such a power conditioner is performed by changing the voltage of the G pole (pole connected to the neutral line of the commercial power line) with respect to the two DC voltage lines of the PN pole, thereby obtaining a neutral line. The voltage of the two AC output lines is set to be apparently AC, and the G pole is connected to the ground via a commercial power line. Therefore, when the power conditioner is operating, Since the potential between the PN pole and the G pole used by the DC ground fault detecting device in the above calculation always fluctuates, it is inconvenient to measure the ground fault resistance and the ground fault point.

[0007] In view of the above problems, the present invention relates to a photovoltaic power generation panel for a photovoltaic power generation system including a photovoltaic power generation panel and a power conditioner connected to a grounded AC power line by converting DC to AC. It is an object of the present invention to obtain a device capable of reliably detecting the ground fault detecting device.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention relates to a power conditioner according to claim 1, wherein the present invention is directed to a power conditioner in which a photovoltaic power generation panel and a DC are converted to AC and connected to an AC circuit having one line grounded. The fault detection device of the photovoltaic panel of the photovoltaic power generation system consists of the ground fault detection unit, the operation detection unit of the power conditioner, and the control unit. If the operation detection unit detects the operation of the power conditioner, And a control unit that limits the ground fault detection output of the ground fault detection unit.

Thus, even if the ground fault detecting section generates a ground fault detection output, the output indicating that there is a ground fault is limited when the power conditioner is operating. Can be determined to be an error, and a ground fault detecting device capable of providing accurate ground fault information can be obtained.

A second aspect of the present invention is a photovoltaic panel ground fault detecting apparatus for a photovoltaic power generation system comprising a power conditioner connected to a photovoltaic power generation panel and an alternating current (AC) circuit which converts a direct current into a direct current. In the above, a ground fault detection unit, an operation detection unit of a power conditioner, and a control unit are provided, and when the operation detection unit detects the operation of the power conditioner, the control unit limits the operation of the ground fault detection unit. A ground fault detecting device for a photovoltaic power generation panel is provided.

Accordingly, when the power conditioner is operating, the ground fault detecting section does not operate, so that a ground fault detecting device capable of providing accurate ground fault information can be obtained.

According to a third aspect of the present invention, the operation detector of the power conditioner determines the operation of the power conditioner based on the output voltage of the solar panel. A detection device is provided.

[0013] Accordingly, the power conditioner can control the power generation output voltage of the photovoltaic power generation panel to be equal to or higher than a certain value.
Since the power conditioner is configured to operate, the operation of the power conditioner can be determined based on the output voltage of the photovoltaic power generation panel, and there is no need to obtain operation information from the power conditioner itself.

According to a fourth aspect of the present invention, the operation detector of the power conditioner operates the power conditioner based on a voltage value between a power generation output line of the solar panel (input voltage terminal on the DC side of the power conditioner) and the ground. 3. A ground fault detection device according to claim 1 or 2, wherein the detection is performed.

Accordingly, when the power conditioner is operating, the potential of the earth with respect to the power generation output line of the photovoltaic panel (the input voltage terminal on the DC side of the power conditioner) is the same as the converted AC voltage. Because it fluctuates
Thus, the operation of the power conditioner can be determined, and there is no need to obtain operation information from the power conditioner itself.

According to a fifth aspect of the present invention, the ground fault detecting unit includes a PN of a DC circuit.
A two-state resistor circuit is connected to the voltage-side line of G and the three poles of G (earth: ground), and measurable values such as the voltage between the poles in the two states, the connected resistance value, and the current flowing in the circuit The ground fault detecting device according to claim 1 or 2, wherein the ground fault resistance value and the ground fault point are calculated and obtained.

According to the present invention, a ground fault resistance and a ground fault point of a ground fault electric circuit output from the photovoltaic power generation panel can be detected.
And 2 ground fault detecting devices can be obtained.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a connection relationship between a photovoltaic power generation system and a ground fault detecting device according to the present invention. In FIG. 1, reference numeral 1 denotes a photovoltaic power generation panel, which outputs a DC voltage between the electric circuits 2 and 3, 2 is a P pole (+ pole), and 3 is an N pole.
Pole (-pole). 4 is a ground fault detecting device, 2 and 3
Connected to the line. G is a (earth) pole which is drawn from the ground fault detecting device and connected to the ground. Reference numeral 5 denotes a power conditioner which converts the DC voltage supplied from 2 and 3 to 6,
An AC voltage is converted and output to an electric circuit connected to the commercial electric circuit side 7 or 8. The power conditioner 5 operates when the voltage between 2 and 3 exceeds a certain value, and when the voltage is less than the certain value, the power conditioner 5 judges that the output of the photovoltaic panel is insufficient and does not operate. The ground fault detecting 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 wires 2 and 3 or may be supplied from a separate battery or commercial power supply. Power may be supplied.

Reference numerals 6, 7, and 8 denote electric circuits connected to the commercial electric lines 12, 13, and 14 through circuit breakers and disconnectors 11, respectively.
Is an L1 phase voltage line, 7 is a neutral line, and 8 is an L2 phase voltage line. Reference numerals 9 and 10 denote load devices (for example, home appliances) that operate on an AC voltage connected to an electric circuit. Reference numeral 15 denotes a power transformer for single-phase three-wire power distribution on the commercial power line side, and a neutral line 13 is a place where the power transformer is installed, which is connected to the ground like E (ground).
I have. The power supply for the loads 9 and 10 is supplied from the photovoltaic panel side when the power generation amount of the solar panel is sufficient, and is supplied from the commercial power side when the power generation amount of the photovoltaic panel is insufficient or insufficient. It is supplied entirely or complementarily from the transformer 15.

FIG. 2 and FIG. 3 are configuration diagrams of an embodiment of a ground fault detecting device 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 detecting section 41 is connected to the P pole, N pole, and G (ground) of the DC circuit, and is connected to the above-mentioned Japanese Patent Application Nos. Hei. As described in Kaihei 7-177646),
A resistance circuit in two states is connected to the three poles of P, N, and G, and a ground fault resistance value and a ground fault resistance value are determined based on a voltage between the poles in the two connection states, a connected resistance value, and a current flowing through the circuit. Output is generated when it is recognized that there is a ground fault by calculating and calculating the ground fault point. Reference numeral 42 denotes a power conditioner operation detection unit which may directly receive operation information from the power conditioner 5 or may determine operation by a method shown in FIGS. Reference numeral 43 denotes a control unit which outputs an output indicating that a ground fault has occurred from the ground fault detection unit 41 to the display output unit 44 when there is a determination output from the power conditioner operation detection unit 42 that the power conditioner is operating. To the display output unit 44. It is possible that there is a possibility that there is a ground fault, but it is doubtful that there is a real ground fault because the power conditioner is operating. Output.

In FIG. 3, reference numeral 41 denotes a ground fault detection unit, and reference numeral 42 denotes a power conditioner operation detection unit, which is the same as that shown in FIG. Reference numeral 45 denotes a control unit. When there is a judgment output from the power conditioner operation detecting unit 42 that the power conditioner 5 is operating, the ground fault detecting unit 41 is provided.
Is controlled to stop the detection operation. When the ground fault detecting section 41 operates and detects a ground fault, the ground fault information is output to the display output section 44.

The ground fault detecting section 41 described above connects the two-state resistor circuits to the three poles P, N, and G as described above.
It is obtained by calculating a ground fault resistance or a ground fault point from values of a voltage between poles in the two connection states, a connected resistance value, a current flowing in a circuit, and the like. Is an effective method that has the ability to determine even a weak ground fault such as 100 kΩ. Among the elements used in the above calculation, the voltage between the poles is a very important element, so if the voltage between P, N, and G fluctuates due to external factors during measurement, accurate detection cannot be performed.

However, in the case where a DC is used after converting DC to AC as in the solar power generation system of FIG. 1, when the power conditioner is used, the P and N poles are operated by the function of the power conditioner described above. N on the commercial side
Since the potential of the pole fluctuates and the N pole is grounded at the power transformer installation point as shown at E, the potential of the G pole also fluctuates, and accurate detection cannot be performed when the power conditioner is operating. The method shown in FIGS. 2 and 3 includes the power conditioner operation detection unit 42, and when the power conditioner is operating, the control units 43 and 45.
Limits the output of the ground fault detector 41 or
Is not operated, and the information of the ground fault detection is displayed and output when the power conditioner is not operating, so that accurate detection is possible.

FIGS. 4 and 5 show examples of the configuration of the power conditioner operation detecting section 42. FIG. In the example of FIG.
1 detects the voltage between the P and N poles and determines the voltage
Is a voltage at which the power conditioner 5 operates, and if so, it is determined that the power conditioner is operating.

In the example shown in FIG. 5, the voltage detection unit 423
When the detected voltage fluctuates more than a specified value, the determination unit 424 determines that the power conditioner is operating. That is, in both the example shown in FIG. 4 and the example shown in FIG. 5, the information as to whether or not the power conditioner is operating directly is determined only by the voltage between the P and N poles without separately routing an electric wire or the like.
The operation of the power conditioner can be determined only by connecting the detection line between the N poles, and there is no restriction on the installation location or the like.

[0026]

As described above, according to the present invention, a photovoltaic power generation system including a photovoltaic power generation panel and a power conditioner which converts a direct current into an alternating current and is connected to a grounded alternating current circuit is provided. In a ground fault detection device for a photovoltaic power generation panel, there is an effect that a device that can reliably perform detection can be obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a photovoltaic power generation system in which a ground fault detection device of the present invention is installed.

FIG. 2 is a configuration diagram of a ground fault detecting device according to claim 1 of the present invention.

FIG. 3 is a configuration diagram of a ground fault detecting device according to claim 2 of the present invention;

FIG. 4 is a configuration diagram of a power conditioner of the ground fault detecting device according to claim 3 of the present invention.

FIG. 5 is a configuration diagram of a power conditioner of the ground fault detecting device according to claim 4 of the present invention.

[Explanation of symbols]

 1 ··· Photovoltaic power generation panel 2 ··· P pole wire 3 ··· N pole wire 4 ··· Ground fault detection device 5 ··· Power conditioner 6 ··· L1 phase voltage line 7 ··· Neutral line 8 ··· L2 phase Voltage line 9 Load A 10 Load B 11 Circuit breaker 15 Power transformer 41 Ground fault detection unit 42 Power conditioner operation detection unit 43 Control unit 44 Display output unit 45 control section 421 voltage detection section 422 determination section 423 voltage fluctuation detection section 424 determination section

Claims (5)

[Claims] 1. A ground fault detecting 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 a grounded alternating current circuit by converting a direct current to an alternating current. It consists of a short detection unit, a power conditioner operation detection unit, and a control unit. When the operation detection unit detects the operation of the power conditioner, the control unit limits the ground fault detection output of the ground fault detection unit. A ground fault detecting device for a photovoltaic power generation panel. 2. A ground fault detecting device for a photovoltaic power generation panel of a photovoltaic power generation system comprising a power conditioner connected to a photovoltaic power generation panel and an alternating current path which converts a direct current into an alternating current and has a line connected to a ground. It consists of a short detection unit, a power conditioner operation detection unit, and a control unit. When the operation detection unit detects the operation of the power conditioner, the control unit limits the operation of the ground fault detection unit. Ground fault detection device for photovoltaic panels. 3. The photovoltaic power generation panel according to claim 1, wherein the power conditioner operation detection unit determines the operation of the power conditioner based on a power generation output voltage of the photovoltaic panel. Ground fault detection device. 4. The operation detector of the power conditioner determines the operation of the power conditioner from a voltage value between a power generation output line of a solar panel (input voltage terminal on the DC side of the power conditioner) and ground. The ground fault detecting device for a photovoltaic power generation panel according to claim 1 or 2, wherein: 5. The ground fault detecting section connects a resistance circuit in two states to a PN voltage side line of a DC circuit and three poles of G (earth: ground), and detects a voltage between poles in two states. From the measurable values such as the connected resistance value and the current flowing through the circuit,
The ground fault detecting device for a photovoltaic power generation panel according to claim 1 or 2, wherein the ground fault resistance value and the ground fault point are calculated and obtained.