JPS6222542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar cell failure detection device for detecting a failure location of a solar cell. Solar cells are silicon single crystal, silicon ribbon crystal,
It is composed of GaAs, etc., and converts solar energy into electricity, and its uses are expanding as a clean energy and new energy. There is a so-called solar power generation device that increases the capacity of a solar cell, connects it to an orthogonal converter (DC→AC), converts it to alternating current, connects it to a general power distribution system or a dedicated alternating current load, and leads the power. Solar cells are modular, and are generally configured as solar panels.Many solar panels are installed, the panels are connected in series to form blocks, and these blocks are further connected in parallel to form solar cells. Determine the voltage and capacity as the output.

Solar panels are installed outdoors and connected to each panel with cables, but this is an environment where failures are likely to occur. For example, if there is a ground fault in a certain part of the battery panel,
If an accident such as a disconnection or short circuit occurs, it is necessary to identify the location.

In the past, there was no specific equipment to detect failures, and if the failure was left unattended, the accident would spread and be discovered.

In order to prevent the accident from spreading and to prevent a decrease in the output of the solar cells, it is necessary to quickly find and repair the malfunctioning part.

This invention is a solar cell failure detection device that can detect failure points early by grounding the neutral point of each power generation block via a resistor and detecting the current flowing between the neutral point and the ground. I will provide a.

The figures will be explained below. In FIGS. 1 and 5, numeral 1 denotes a solar cell panel, and n solar panels are connected in series to form one power generation block (hereinafter referred to as a block). Each block is block A ₁
There are m blocks from A to A, which are connected in parallel. As shown in FIG. 2, the solar cell panel 1 has one or more solar cell elements 1a connected in series, and both ends can be bypassed by bypass diodes 2. 3 and 4 are diodes for backflow prevention, and each block A ₁ ~ Am
is connected at both ends in the forward direction with respect to the electromotive force. 5 and 6 are output terminals to which loads are connected. 7
is a grounding wire that grounds the neutral points _X12 to Xm of each block _A1 to Am, and 8 is a resistor provided to the grounding wire 7.
In order to limit the current flowing through the grounding wire 7, a wire with a high resistance value is used. Reference numeral 9 represents a relay provided on the grounding wire 7, and reference numeral 10 represents a switch provided between each of the neutral points X ₁ to Xm and the resistor 8.

Next, the operation will be explained with reference to FIGS. 3 to 5.
3 to 5 are circuit diagrams equivalent to FIG. 1, and although the combined resistance 11 of blocks A ₂ to Am is shown, the relays and the like of blocks A ₂ to Am are omitted.

Figure 3 shows an example where a ground fault occurred at point Y in block _A1 . Voltage on both sides of each block
If E _{is 0} , the voltages of each solar panel 1 are combined on both sides of the neutral point X except for block A ₁ .
There is a voltage of E ₀ /2. Furthermore, if the internal impedance of a relay (not shown) is ignored, the neutral point X is grounded through a resistance Z=γ/m-1.

When no accident occurs, the potential at the neutral point _X1 of block _A1 is also E ₀ /2, and no current flows through relay 9. When a ground fault occurs at point Y between solar panels _P1 and _P2 , a closed loop is formed between ground fault point Y, solar panel _P2 ...neutral point _X1 , resistor 8, and relay 9. . Therefore, the current I _R flowing through the relay 9 is as follows.

I _R =(E ₀ /2-E ₀ /n)×1/γ=(n-2
) E ₀ /2n. When a ground fault occurs at a point that is _one panel away from the γ
I _R =E ₀ /n. γ, so the relay 9 should be set to operate at this value.

Figure 4 shows a case where solar panel _P2 is short-circuited. Since there is no potential difference between both ends of the solar cell panel _P2 , the potential E _X1 ' at point _X1 is as follows.

E _X1 ′=E ₀ ×(〓-1)/n-1 The current I _R ′ flowing through the relay 9 is as follows, so The relay 9 may be operated by the current I _R ' at this time. Note that even if the bypass diode 2 in FIG. 2 fails and enters a reverse conduction state, the condition is the same as a short circuit in the solar cell panel, and it can be detected.

Figure 5 shows a case where a disconnection occurs between solar panels _P1 and _P2 . In this case, each battery panel has an open circuit voltage. (The voltage when the maximum power is extracted is called the optimal operating voltage, but when it is left open, the voltage increases and is usually 1.4 to 1.5 times the optimal operating voltage.) The potential E _X1 ″ of X ₁ becomes smaller than the initial E ₀ / ₂ , and Denan _E
With a difference of ₁ '', a current of EX _{- EX1} ''/γ+Z flows through the disconnector 9. This current allows the disconnector 9 to operate satisfactorily. Note that the current flowing through the relay 9 varies considerably depending on the failure occurrence situation, and in order to improve sensitivity, it is necessary to use a relay 9 having a large overcurrent withstand capacity. The polarity of the current changes depending on the location of the fault, so it must be bidirectional. Further, the reverse current prevention diode 3 prevents a large current from flowing backward from the neutral point X through the composite resistor 11 in the event of a ground fault, thereby preventing elements in the battery panel from being destroyed.

It is also conceivable to provide switches at both ends of each series block A ₁ to Am and perform maintenance at another location during operation. Furthermore, since it would be costly to provide resistors 8 and relays 9 in individual blocks, switches _{10 shown} in FIG. If a scanner (not shown) for switching is provided, a desired block can be checked using a set of resistors 8, relays 9, etc.

As described above, according to the present invention, the neutral point of each power generation block in which a plurality of solar panels are connected in series is grounded via a resistor, and the current flowing between the neutral point and the earth is detected. Since a failure is detected by doing this, it is possible to detect the failure location at an early stage. In addition, the detection signal allows you to easily stop the device and display it remotely.
Malfunctions can be quickly repaired. It also has the effect of preventing the spread of accidents.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a solar cell failure detection device according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the solar cell panel shown in Fig. 1, and Figs. 3 to 5 show failure examples. 2 is a circuit diagram equivalent to FIG. 1. FIG. In the figure, 1 is a solar panel, A ₁ to Am are power generation blocks, 7 is a grounding point, 8 is a resistor, and 9 is a relay. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] 1 Power generation blocks each having a plurality of solar cell panels connected in series are connected in parallel, the neutral point of each power generation block is grounded via a resistor, and the neutral point is connected to the earth. A failure detection device for a solar cell, characterized by detecting a current flowing between the solar cells. 2 Power generation blocks in which multiple solar panels are connected in series are connected in parallel, diodes are provided at both ends of each of the power generation blocks in the forward direction relative to the electromotive force, and the neutral point of each of the power generation blocks is connected to a resistor. A failure detection device for a solar cell, characterized in that the device is grounded through the neutral point and detects a current flowing between the neutral point and the earth.