JPH0280978A - Tap shift detector - Google Patents

Abstract

PURPOSE:To reduce the cost of construction to a large extent by interposing resistors for detecting a tap position between the tap terminals operated in parallel and detecting the difference between the voltage values by the respective resistors at the time of parallel operation. CONSTITUTION:Resistors Rp of the same capacity are inserted between the adjacent tap terminals in variable resistors 10a, 10b in this tap shift detector and predetermined voltage is applied between both connection terminals TB1, TB2 and the potentials at the common terminals COM of both variable resistors 10a, 10b are compared to detect tap shift. Therefore, the terminal connection wires 8 for connecting a tap shift detection circuit 9 and each of the variable resistors 10a, 10b become only three wires in total, that is, two wires for applying voltage to both connection terminals TB1, TB2 and one wire for connecting the common terminal COM and a difference voltage detector 11. Therefore, the number of the terminal connection wires 8 necessary for detecting tap shift can be reduced to a large extent.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Application of Rakudo) The present invention relates to a device for detecting tap deviation of each tap-changing transformer in a power system in which a plurality of tap-changing transformers are operated in parallel. .

(Prior Art) In recent years, in order to improve the reliability and stability of power system operations, power supply by parallel operation of a plurality of transformers has been widely adopted.

FIG. 4 is a schematic diagram showing an example of such a power system, in which power supplied from a commercial power line 1 is transmitted via a primary bus 2 to two on-load tap switching transformers! (hereinafter referred to as LRT) 3a, 3b, and the respective circuit breakers 4a, 4
It is connected in parallel to the secondary bus 5 via b. In addition, a circuit breaker 4 is installed between the connection points of both circuit breakers 4a and 4b on the secondary bus 5 for the purpose of canceling the parallel operation of both LRTs 3a and 3b.
C is provided.

The LRTs 3a and 3b in such a configuration can switch the winding taps without changing the load. The tap positions are changed by tap changers 6a and 6b, and can be changed manually by an operator's switching operation or automatically by an automatic voltage regulator (not shown).

Also, in order to prevent tap misalignment of both LRTs 3a and 3b1m, one of the tap changers 6a and 6b is designated as the "master" (tap changer 6a in the figure), and the other is designated as the "slave". There is. When the tap position on the "master" side is switched, the tap position on the "slave" side is also switched in conjunction with this, so that the tap positions of both LRTs 3a and 3b always match.

However, if a tap shift occurs due to a failure of the tap changers 6a, 6b, both LRTs 3a,
A difference occurs in the output voltage of LRT 3b, and both LRTs 3a and 3b
A circulating current flows between them.

As a result, each circuit breaker 4a, 4b, and 4c may be cut off, impairing stable power supply.

Therefore, it is necessary to monitor the tap positions of both LR blades 3a and 3b, and to notify the operator immediately if a tap misalignment occurs. Conventionally, a tap misalignment detection device as shown in Fig. 5 has been known. There is.

As shown in the figure, both LRTs 3a and 3b are provided with position switches 7a and 7b, and the tap terminals TAP+ to TAPn corresponding to the tap positions and the common terminal COM
The connection can be switched in conjunction with the tap position switching operation.

Also, tap terminals T of both position switches 7a and 7b
AP+ to TAPn are connected by a terminal connection line 8, the common terminal COM of the position switch 7a is connected to the positive power supply, and the common terminal COM of the position switch 7b is connected to the negative power supply via the relay X. ing.

Therefore, when the tap positions of both LRTs 3a and 3b match, relay X+ becomes conductive, and contact X+b is opened. Therefore, no tap deviation signal is output.

Further, when the tap positions of both LRTs 3a and 3b are shifted, relay X+ is not conductive and contact XIb is "closed". Then, switch Ra is closed as long as both LRTs 3a and 3b are operated in parallel, so timer relay T becomes conductive, and after a predetermined period of time, contact d is closed.
"Closed" to output a tap deviation signal.

Thereafter, this tap deviation signal is connected to an alarm lamp, alarm buzzer, etc. (not shown) to notify the operator of the occurrence of tap deviation.

(Problem to be solved by the invention) However, in the conventional tap deviation detection device,
Between both LRTs 3a and 3b, there are terminal connection wires 8 for the number of taps.
If the distance between the two LRTs 3a and 3b is large, the installation work for the terminal connection line 8 not only becomes complicated, but also increases the cost.

The present invention was made to solve the conventional problems as described above, and its purpose is to provide a tap deviation detection device that does not require the same number of terminal connection wires as the number of taps of a tap change transformer. It's about doing.

[Configuration 1 of the Invention (Means for Solving the Problems) In order to achieve the above object, the present invention provides a resistor for detecting the tap position between each tap terminal of each of the tap changer transformers operated in parallel. A feature of the resistor is that it detects the difference in voltage value obtained by each resistor during parallel operation, and outputs a tap deviation detection signal when this difference voltage exceeds a certain value.

(Function) In the tap deviation detection position B according to the present invention, the voltage values obtained from the resistors for detecting the tap position of each tap changeover transformer are compared, and if the difference voltage exceeds a fixed value, tap deviation is detected. It is outputting a signal.

Therefore, the number of connection lines required to detect tap deviation can be reduced.

(Example) FIG. 1 is a block diagram showing an embodiment of the present invention.

As shown in the figure, the tap deviation detection device in this embodiment includes a tap deviation detection circuit 9 and variable resistors 10a and 10.
b, and are connected by terminal connection wires 8.

The variable resistors 10a and 10b are the on-load tap changing transformer (LRT) 3a in FIG. 4 explained in the conventional example.
, 3b, a detailed view of which is shown in FIG.

As shown, resistors 10Sa and LRT3a.

Tap terminal TAP+~TA corresponding to the tap position of 3b
Pn, and resistors Rp are inserted between adjacent tap terminals and connected in series.

In addition, the tap terminal TAP+ corresponding to the actual tap position
A common terminal COM is provided to be connected to ~1-APn, and when the tap positions of LRT3a and 3b are switched, the connection between the common terminal COM and each tap terminal TAP+~TAPn is linked to this. It is designed to switch.

Further, the tap terminal TAPz is connected to the connection terminal -[BI, and the tap terminal T A P n is connected to the connection terminal IB2 via a resistor Rp. These connection terminals TB+ and TB2 are connected to the tap shift detection circuit 9 shown in FIG. 1, and a predetermined voltage is applied between both terminals.

Further, the tap deviation detection circuit 9 includes an angular variable resistor 10a,
The potentials at each common terminal COM of the variable resistors 10a and 10b are compared, and the differential voltage detector 11 detects the differential voltage, and this differential voltage is compared with the voltage drop of 801 resistors inside the variable resistors 10a and 10b. When the differential voltage comparator 112 determines that the differential voltage obtained by the differential voltage detector 11 is greater than the voltage drop of one resistor Rp, the circuit becomes conductive. It is composed of a transistor 13. Moreover, 1" is a timer relay, and 1"a is an a contact of timer relay T.

The differential voltage detector 11 connects the common terminal COM in the variable resistors 10a and 10b via the terminal connection line 8, respectively.
The voltages V+ and v2 between the terminal and the connecting terminal T[32 are taken in, and the difference voltage ΔV between them is calculated.

The differential voltage comparator 12 is connected to the variable resistor 5 by the variable resistor RV.
10a, 10b17) The voltage VRV adjusted to correspond to the voltage drop of the resistor Rp11111 and the voltage ΔV output from the differential voltage detector 11 are taken in, and the magnitude of both voltages is compared. There is. And the voltage ΔV
If is greater than the voltages V and RV, the electric JIT:
Output Vo.

When the voltage Vo is applied from the differential voltage comparator 12, the transistor 13 becomes conductive, thereby making the timer relay T conductive, closing the contact 7a, and outputting a tap deviation signal.

Next, the operation of this embodiment will be explained with reference to the time chart of each voltage shown in FIG.

When the LRTs 3a and 3b in FIG. 4 are operated in parallel and there is no tap deviation, the variable resistor 10a in FIG.
, and the common terminal COM of 10b is the opposite tap terminal TA.
Connected to P+ to TAPn.

Therefore, in the variable angle resistors 10a and 10b, the resistance values between the common terminal COM and the connection terminal TB2 are equal, and the potentials at both common terminals COM are also equal. Therefore, the voltage V+ supplied to the differential voltage detector 11
, V2 become equal, and the output differential voltage Δ■ becomes zero.

Due to this combination, the voltage Vo is not output from the differential voltage comparator 12, and the transistor 13 is not turned on. Therefore, the tap deviation signal is not output ((between 1 and 2) in Figure 3,
.

Furthermore, if the magnitude of the voltage Vl and voltage v2 supplied to the differential voltage detector 11 differs due to a capacitance error of each resistor IRp or a voltage drop during transmission through the terminal connection line 8, A differential voltage Δ■ is output. However, since this differential voltage is smaller than the voltage drop VRV of one resistor Rp, the voltage Vo is not output from the differential voltage comparator. Therefore, there is no possibility that a tap shift will be erroneously detected due to a voltage fluctuation caused by an error in the resistor Rp or a voltage drop (between 2 and t3 in FIG. 3).

Additionally, if a tap misalignment occurs between the LRTs 3a and 3b, the common terminal CO of the variable resistors 10a and 10b
M is no longer connected to the same tap terminal TAP+-TAP11.

Therefore, in the variable angle resistors 10a and 10b, the resistance values between the common terminal COM and the connection terminal TB2 will differ, and the potentials at both common terminals COM will also differ. Therefore, the voltage Vl supplied to the differential voltage detector
and voltage v2 are different in thickness b, and both voltages V+
, V2, a differential voltage Δ■ is output.

Since the magnitude of this differential voltage ΔV is greater than the voltage drop of one resistor Rp, the differential voltage comparator 12 outputs the voltage Vo (after t3 in FIG. 3).

This voltage Vo causes transistor 13 to become conductive, and voltage is applied to timer relay T.
When a predetermined period of time has elapsed, contact Ta is "closed" and a tap deviation signal is output.

In this way, in this embodiment, the variable resistors 10a, 1
Connect the resistor R between the adjacent tap terminals inside 0b.
A predetermined voltage is applied between both connection terminals TB+ and 782, and the potentials at the common terminal COM of both variable resistors 10a and 10b are compared to detect tap deviation.

Therefore, the tap deviation detection circuit 9 and each variable resistor 10
The terminal connection line 8 connecting the terminals a and 10b includes two trees for applying voltage to both connection terminals T8+ and Ta2, and one tree for connecting the common terminal COM and the differential voltage detector 11, respectively. There will be only 3 pieces in total. Therefore, the number of terminal connection lines 8 required for detecting tap misalignment can be significantly reduced.

In addition, in this embodiment, the load tap FJ) conversion If-,
Although the present invention is not limited to this case, and can be applied to three or more IRTs, the present invention is not limited to this case.

Moreover, the differential voltage detector 11 in this embodiment. It is also possible to digitize the differential voltage comparator 12 and output the tap shift signal under microcomputer control.

Furthermore, the resistor Rp inside the variable resistors 10a and 10b is
It goes without saying that it can be constructed of a type with a continuously variable resistance value.

Effect of the Invention 1 As explained above, in the present invention, a resistor for tap position detection is inserted between the tap terminals of each tap switching transformer temperature, and the voltage value obtained by each resistor during parallel operation is Detecting the difference between

Then, when this differential voltage exceeds a certain value, a tap shift detection signal is output.

Therefore, in order to detect tap deviation as before,
It is no longer necessary to provide the same number of connection wires as tap terminals.

Therefore, the connection line installation work becomes easy, and the cost required for the work is significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing details of a variable resistor, and FIG. 3 is a time chart of each voltage signal. In addition, Fig. 4 is a configuration diagram showing an outline of the power supply system, and Fig. 5
The figure is a configuration diagram showing a conventional example. 3a, 3b...Load tap switching transformer (LRT)
8... Terminal connection wire 9... Tap deviation detection circuit 10
a, 10b... Variable resistor 11... Differential voltage detector 12... Differential voltage comparator 13
...transistor Ta1. B2...Connection terminal COM...Common terminal "△P+~TPAn...Tap terminal Rp...Resistor

Claims (1)

[Claims] A resistor for detecting the tap position is inserted between each tap terminal of each tap-changing transformer operated in parallel, and the difference in voltage value obtained by each resistor during parallel operation is detected, and this difference voltage is a constant value. A tap deviation detection device is characterized in that it outputs a tap deviation detection signal when the tap deviation exceeds .