JPS6016819B2 - Ground contact detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a saddle ground contact detection device for detecting grounding of DC and AC power sources and contact accidents between them.

In recent substations, especially 500 KV substations, the control power supply circuits of the substation are being duplicated to achieve high reliability.

However, the secondary means of detecting a failure in the control power supply circuit are
Some grounding or cross-contact accidents could not be detected. Conventionally,
A saddle ground mixing device of this type is shown in FIG.

In the diagram, IAI and IA2 are monitored DC power supplies, IB1 and IB2
is the monitored AC power supply, 2A1, 2A2, 2B1, 2B2,
3A1, 3A2, 3B1, and 3B2 are the power lines of the respective power sources, and represent the power supply system to be protected. 5A
I I is the detection DC power supply, 6AI1 is the detection DC power supply 5
A resistor connected in series to AII, 8AII a rectifying element connected in series so as to have characteristics that are compatible with the detection DC power supply 5AII, and 7AII a current for detecting a constant waveform of the current flowing through resistor 6AII. It is a detector.

These 5AIl, 6AI1, 7AI1, 8AIl form a series circuit 9A which is the basic constituent unit of the ground crossing detection device.
II is configured and connected to the power supply line 2AI and the ground 4. Below 9A12, 9A21, 9A22, 9BI1, 9
B12, 9B21, and 9B22 are also series circuits that are the basic constituent units of the ground contact detection device, which are composed of the same elements as 9AII. However, among them gAl2, 9A22, 9B21
, 9822, the orientation of the detection DC power supplies 5AI2, 5A22, 5B21, 5B22 and the rectifying elements 8AI2, 8A22, 8B21, 8B22 among its components is 9.
This is the opposite of the case with AII. Series circuit 9AI1,9
The connection directions of AI2, 9A21, and 9A22 are connected so as to prevent current from flowing out from the monitored DC power supplies IA1 and IA2. Series circuit 9BI1, 9B12, 9B21, 9
Two pieces of B22 are connected to the monitored AC power supply IB1, I.
Blocking current from B2. Therefore, when there is no fault, no current flows in the series circuit. Next, the operation of the conventional device shown in FIG. 1 will be explained.

When there is no grounding or cross-contamination accident in the protected power supply system, for example, in the case of the DC system shown in Figure 1, for example, the voltage of the detection DC power supplies 5AI1 and 5AI2 should be made lower than the voltage of the monitored DC power supply IAI. If you put it, rectifier 8AI
1 and 8AI2 are placed in a reverse characteristic state, the current flowing through the series circuits 9AIl and 9AI2 is zero, and the series circuits 9AI1 and 9A1 are connected to the monitored DC power supply IAI.
The effect of adding 2 does not appear at all. In the case of an AC system, either one of the rectifying elements 8BI1, 8B12 always has an opposite characteristic state due to the phase relationship of the monitored AC power source IBI, and the current flowing through the series circuit is also zero. Now, let us consider the case where a grounding accident occurs in the DC system, and the details of the accident are shown in Figure 2. Assuming that the negative power supply line 3AI is grounded via the resistor 10, a current IG shown by an arrow in the figure flows. Here, IG is a 5A DC power supply for detection.
It is uniquely determined by the voltage e of I2, the resistance value R of the resistor 6AI2 in the series circuit, and the resistance value r of the grounding resistor 10, and is expressed as follows. e IG=Previous Agency If this current 1G is detected by the current detector 7AI2, a grounding fault in the DC system can be detected.

Note that the effect of the grounding accident does not appear on the protected power supply. Furthermore, the detection of a grounding fault on the positive power line is exactly the same. Next, in the case of a grounding accident in an AC system, for example, assuming that the power line 3BI is grounded via the resistor 10 as shown in FIG.
IG, I
A current G3 flows. IG3 is a current when the rectifying element 8B12 has a bottle characteristic and the rectifying element 8BII has an inverse characteristic, and is uniquely determined by the detection DC power supply voltage e, the resistance R, and the grounding resistance r, and is expressed by the following equation. e IG3=R▽lc, is the current when the rectifier 8B12 has the reverse characteristic and the rectifier 8BII has the forward characteristic, contrary to IG3, and the current from the detection DC power supply 6811 and the monitored AC power supply IBI The current is superimposed and becomes the following equation.

V+e IG・=Previous Agency Therefore, when IG flows through one of the resistors 6BI1, 6B12 in the series circuit connected to the monitored AC power supply IBI, and IG3 flows through the other, this must be detected by the current detector 7BI1, 7B12. For example, it is possible to detect and determine that a grounding accident has occurred in the power supply line 381.

Incidentally, since the current IG3 does not include the current due to the monitored AC power supply voltage V, if this is used as the main component of the determination, accurate detection and determination without being influenced by the AC power supply becomes possible. The same aircraft also detects grounding faults in other AC power lines. Next, as shown in Figure 4, when a cross-contamination accident occurs between the DC power line 3AI and the DC power line 2A2 through the resistor 10, the arrow in the figure As shown in , the resistor 6 of the series circuit connected to the relevant power line
Since current Is flows through AI2, 6A21, if this is detected, it is possible to detect a cross-contact accident between DC systems and determine the faulty power supply line.

Next, as shown in Figure 5, when a cross-contact accident occurs between the AC power line 3BI and the AC power source Sunsen 2B2 via the resistor 10, the power source where the accident occurred is the same as in the case of an AC grounding accident. A current ls from the detection DC power supply flows through the resistances 6B12 and 6B21 of the series circuit on the line side, and a current from the monitored AC power supply IB1 and IB2 flows through the resistances 6BI1 and 6B22 of the series circuit on the non-fault side. Since ls2 flows, if this is detected, it is possible to detect a cross-contact accident between AC systems and determine the faulty power supply line.

Finally, if a cross-contact accident occurs between the AC power line 2BI and the DC power line 3AI via the resistor 10 as shown in Fig. 6, on the AC side, as in the case of a grounding accident,
A current ls from the detection DC power supply flows through the resistor 6BII on the side of the power supply line where the accident occurred, and a current ls2, which is the sum of the current from the monitored AC power supply IBI, flows through the resistor 6B12.

Regarding the DC side, a current ls from the detection DC power supply and a current superimposed with the current from the monitored AC power supply every AC half wave flow through the resistor 6AI2 connected to the power supply line where the fault has occurred. . Therefore, by monitoring this, it is possible to detect a cross-contact accident between the AC and DC systems and determine the faulty power supply line. The conventional ground contact device, whose operation has been explained above, can constantly monitor multiple monitored power supplies, but because the connection relationship with the protected power line is fixed, it cannot detect accidents as shown below. A case exists.

For example, FIG. 7 shows a cross-contact accident between the positive power supply lines of the monitored DC power supplies IA1 and IA2, but in this case, no current flows through the series circuits 9AI1 and 9A21, making it impossible to detect the accident.

The same applies to the case of accidental contact between the power lines 3A1 and 3A2 on the negative electrode side. In addition, in the event of a cross-contact accident between a DC power source and an AC power source, the rectifying elements 8AI2 and 8B21, which are the constituent elements, and the detection DC power sources 5AI2 and 5B21, as shown in 9AI2 and 9B21 in Fig. 8, may be oriented in the same direction. In the case of an accident between the power lines to which the series circuits 9AI2 and 9B21 are connected, no current flows as shown in FIG. 6, and it cannot be detected. The present invention has been made to eliminate the drawbacks of the conventional devices as described above, and by adding a contact switching circuit to the conventional device and switching the connection between the power line and the series circuit, it is possible to detect Accidents can also be detected, making it possible to monitor a wide range of ground contact accidents.

Hereinafter, a circuit configuration of an embodiment of the present invention will be explained with reference to FIG.

In FIG. 9, IA1 and IA2 are the monitored DC power supplies,
B1, IB2 are monitored AC power supplies, 2AI, 2A2, 2B
1, 2B2 and 3AI, 382, 3B1, 3B2 are the power lines of the respective monitored power supplies, and represent the power supply system to be protected. 9AO1, 9A02, 9AIl, 9
AI2, 9A21, 9A22, 9BI1, 9812, 9
B21 and 9B22 are a detection DC power supply, a resistor connected in series to the detection DC power supply, and a rectifier connected in series to the detection DC power supply so as to have forward characteristics, as in the slave device. This is a series circuit that is the basic structural unit of the ground moat gill detection device, which consists of an element and a current detector that detects the constant waveform of the current flowing through the resistor.

Each series circuit is 9AO1, 9AIl, 9A21, 9BI1, 9B12 depending on the direction of the detection DC power supply and rectifying element.
group and 3A02, 9A21, 9A22, 9B12
, 9B22, each of which is connected to the switching contact circuit 11 and the ground 4. The switching contact circuit 11 connects a predetermined one of each series circuit to a power line of each power source to be protected. Next, the operation of the ground contact detection device according to the present invention will be explained.

When connected as shown in Fig. 9 by the switching contact circuit 11, it is completely equivalent to the conventional device, so that among the grounding and cross-contact accidents of each monitored power supply circuit, cross-polarity between the same polarities of the monitored DC power supply is Some shaft accidents and cross-contact accidents between the monitored DC power source and the monitored AC power source cannot be detected.

First of all, if we consider the accident of close contact between the monitored DC power supply and the monitored AC power supply, in the connection shown in Figure 9, the power lines 3AI and 3A2 on the negative side of the monitored DC power supply and the monitored AC power supply IBI
It is possible to detect cross-contact accidents between the power supply lines 2B1 and 3BI of the monitor, and cross-contact accidents between the positive power supply lines 2AI and 2A2 of the monitored DC power supply and the power supply lines 2B2 and 3B2 of the monitored AC power supply IB2. Yes Power supply line 2 on the positive side of the monitored DC power supply
AI, 2A2 and the power line 2B1 of the monitored AC power supply IBI,
3BI and the negative power supply line 3AI, 3A2 of the monitored DC power supply and the power supply line 2 of the monitored AC power supply IB2
82 and 3B2 cannot be detected.
However, if the connections are made as shown in FIG. 10, this relationship will be reversed. In other words, if the two connections shown in FIGS. 9 and 10 are appropriately switched between the series circuit connections on the side of the monitored AC power source using the contact switching circuit 11, a crosstalk accident between the monitored DC power source and the monitored AC power source can be avoided. This means that all of them can be detected. Next is the contact accident between the same poles of the monitored DC power supply. For example, the contact accident between the positive power supply lines 2AI and 2A2 is the 11th
If the connection is as shown in the figure, as shown in FIG. 12, the current ls from the detection DC power supplies 5A02 and 5A21 will be applied to the series circuit 9A02 of the ground contact detection device connected to the power supply line where the accident occurred. Since it flows through 9A21, it can be detected.

At this time, if there is no fault, the rectifying element 8AI2 has a characteristic opposite to that of the monitored DC power supply IAI, so no current flows and unnecessary detection operations are not performed. Furthermore, even in the case of a mix-up accident between the negative power supply lines, it can be detected by connecting them as shown in FIG. In the above embodiment, if the voltage of the detection DC power supply, the resistance value of the resistor, or the detected current waveform of the current detector is made variable, the sensitivity of accident detection can be set to any value. .

As described above, according to the present invention, a plurality of first
A series circuit consisting of a detection DC power supply whose one end is grounded and whose polarity is opposite to that of the detection DC power supply of the first series circuit, and a rectifier connected in the forward direction with respect to this power supply. A plurality of second series circuits made up of connecting bodies, and a switching circuit capable of appropriately selecting and connecting both ends of each monitored power supply to the other end of one of the first or second series circuits, respectively. Therefore, connect the terminals of the first or second series circuit to both ends of each monitored power supply so that at least one side has the opposite polarity to the polarity of the monitored power supply, and connect the terminals of the first or second series circuit as necessary. Switch the connection from the first series circuit to the second series circuit or from the second series circuit to the first series circuit (however, in this case, at least one of the series circuits has opposite characteristics to the monitored power supply). Therefore, it is effective in detecting all types of grounding faults or ditching faults between monitored power supplies, including faults that could not be detected in the past.

In recent substations, two identical control power sources are being installed for redundancy, and as a result, the frequency of cross-side accidents between power sources is much higher than in the past. .

The cross-contact accident detection device according to the present invention is most suitable for such uses.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of a conventional ground mixing device, FIGS. 2 to 8 are explanatory diagrams of the operation of the circuit shown in FIG. 1, and FIG. 9 is a diagram of a ground mixing detection device according to the present invention. The circuit diagrams illustrating the embodiment, FIGS. 10 to 13, are diagrams illustrating the operation of the ground contact detection device of FIG. 9. In the figure, IA1 and IA2 are the monitored DC power supplies, IB1
, IB2 is the monitored AC power supply, 5AO1, 5A02, 5A
Il, 5AI2, 5A21, 5A22, 5BI1, 5B
12, 5B21, 5B22 are DC power supplies for detection, 7AO1
,7A02,7AIl,7AI2,7A21,7A22
, 7BI1, 7B12, 7B21, 7B22 are current detectors that detect the current flowing through the resistors, 8AO1, 8A02,
8AIl, 8AI2, 8A21, 8A22, 8BI1,
8B12, 8B21, 8B22 are rectifiers connected to the detection DC power supply so as to have forward characteristics, 9AO1, 9A
02,9AI 1,9AI2,9A21,9A22,9
BI1, 9B12, 9821, and 9B22 are series circuits constituted by the above-described detection DC power supply, current detector, and rectifying element, and 11 is a blind point switching circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts. 1st
Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 12 Figure 9 Figure 10 Figure 11 Figure 13

Claims (1)

[Scope of Claims] 1. In a device designed to detect a grounding accident of a plurality of monitored power supplies or a crosstalk accident between these power supplies, one end is grounded, and a DC power supply for detection and a DC power supply for detection are connected to each other. a plurality of first series circuits each consisting of a series connection body with a rectifying element connected in the forward direction to a DC power source, and one end of which is grounded, and a DC power source for detection of the first series circuit; A plurality of second series circuits each consisting of a series connection body of a detection DC power supply with a polarity opposite to the detection DC power supply and a rectifier connected in the forward direction to the detection DC power supply, and both ends of each of the monitored power supplies. A ground contact detection device characterized by comprising: a switching circuit which can appropriately select and connect one of the first and second series circuits to the other end of the first or second series circuit. 2. The ground contact detection device according to claim 1, wherein the plurality of monitored power supplies constitute a set of two. 3. When the monitored power source is a DC power source, the grounding according to claim 2, characterized in that the voltage value of the detection DC power source is smaller than 1/2 of the voltage value of the corresponding monitored power source. Contact detection device. 4. When at least two monitored power supplies are both AC power supplies, corresponding rectifying elements are connected to both monitored power supplies so that the polarities are opposite to each other. The described ground contact detection device. 5. The ground contact detection device according to claim 3, wherein the at least two monitored power supplies are a DC power supply and an AC power supply.