JPS625623A - On-load tap changer - Google Patents

Abstract

PURPOSE:To change any number of taps substantially for the same tap changing time to desired tap position by varying the rotation of an AC motor in response to one tap or continuous tap changing commands to hold the tap changing time substantially constant. CONSTITUTION:A changing command of an on-load tap changer is output from an operating command generator 5 of the tap changer, and a calculating controller 18 judges whether the tap position is maximum or not by counting pulses from a pulse generator 17 when the command has a tap voltage rise. In other words, the tap changer 1 is driven by an AC motor 13 to change its tap, the rotating speed of the motor 13 is detected by a rotation detector 16, and converted to a pulse through the generator 17. Accordingly, the controller 18 calculates the present position of the changer 1 by counting the output pulse from the generator 17, and the maximum tap position is stored in a memory 19. Accordingly, it can judge whether it arrives at the maximum tap position or not by comparing with it.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an on-load tap changer, and more particularly to an improvement in an electric operating mechanism for operating a tap changer.

[Technical background of the invention and its problems]

Generally, the on-load tap changer is as shown in Fig. 3.
The tap changer 1 is composed of an on-load tap changer 1 and electric operations fi and f42 for switching the tap changer 1. When the load 3 of the power transmission and distribution system to which the transformer equipped with the on-load tap changer is connected fluctuates, the transformer 4 detects a pressure change corresponding to this load fluctuation, and this change wind is kept at a constant value. (When the load tap changer transformer 6
The on-load tap changer 1 switches the taps installed in the power transmission system to keep the voltage of the power transmission and distribution system constant (-).

In such a load tap changer, the conventional electric operation mechanism 2 includes an electric motor 317 that generates the power necessary for operating the load tap changer 1, and an electric motor 7, as shown in FIG. A drive mechanism 8 that transmits power to the on-load tap changer 1, and a stepping mechanism 9 that transmits the rotation of the main drive shaft of this drive mechanism 8 via a mechanical mechanism such as a gear or a cam.
．． It is comprised of an instruction mechanism 11 that displays the limit stop m K310, tap position, switching rotation, etc., and a motor power supply control circuit 12 that controls the power source of the electric motor 7.

Here, the stepping mechanism 9 is a mechanism for detecting the end of switching of the tap changer 1 under load, and is provided in the drive mechanism 8 and controls the rotation of a main drive shaft (not shown) that drives the tap changer 1 under load. Every time the tap of the tap changer 6 is changed once (21L!21), the cam mechanism that rotates 2 times (2 times) is transmitted, and the switch mechanism installed in this cam mechanism changes the tap change path of the tap changer 1 under load. This is a mechanism that generates a signal and outputs a motor stop signal to the motor side 8 circuit 12 of the motor 7.
The limit stop mechanism 10 is a mechanism that prevents the on-load tap changer 1 from operating beyond the switching range of the on-load tap changer 1 corresponding to the number of taps provided in the on-load tap changer transformer 6. When a signal for switching the tap outside the switching range of the on-load tap changer 1 is output from the operation phase generation circuit 5, the drive shaft of the on-load tap changer 1 and the main shaft of the drive vJ mechanism 8 are separated and the motor 7 is idled. A switch mechanism for detecting rotation stoppage of the electric motor P47 is provided. The indicating mechanism 11 that displays the tap position and the number of times of switching uses a gear to reduce the speed of the main drive shaft (not shown) of the indicating mechanism 11 within the tap switching range of the tap changer 1 under load until it becomes one rotation or less, and then calculates the amount of rotational angle displacement. This is a mechanism that detects the tap position and counts the number of switchings using a mechanical counter.

However, since the above-mentioned conventional electric operating mechanism 2 is constituted by a mechanical mechanism, it has the following problems.

(a) The stepping mechanism 9, the limit stop mechanism 10, and the display mechanism 11 require many special mechanical parts in addition to gears and cams;
Additionally, these parts required high-precision processing and high reliability.

(b) The display mechanism 11 that displays the stop position and tap position of the electric a7 that drives the on-load tap changer 1 has mechanically operated contacts fixed with bolts or the like, so there is no variation in signal detection timing. Also, during assembly, it was necessary to adjust the mounting positions of switches to adjust the signal detection timing.

(c) Since the number of tap points of the on-load tap change transformer 6 differs depending on the voltage adjustment range required for each power transmission and distribution system, the operating point of the limit stop SAMIO differs, and the adjustment of the operating position during assembly is difficult. It was necessary.

(d) Since the electric operation mechanism 2 is constituted by a mechanical mechanism, it is necessary to use mechanically operated switches for the tap change end detection and tap position detection mechanisms. Since these switches cut off the current, the contacts inevitably wear out and require maintenance and inspection.Furthermore, the sliding parts such as the cams that turn the switches □N and OFF wear out, so the switches The operating point changed, requiring maintenance such as replacing parts.

(e) Mechanical (-) When changing several taps continuously, it takes a multiple of the one-tap switching time, and it takes a long time to select the desired tap position. It took time.

In particular, in on-load tap changers used in electric furnaces and the like, the time required to change taps is inefficient as it leads to a loss in operating efficiency of the electric furnace.

[Purpose of the invention]

The present invention solves the above-mentioned problems of the prior art.The purpose of the present invention is to provide a simple electric motor operating mechanism, high reliability in which normal tap switching is always performed, and no change in the switching operation time to the desired tap position. To provide an on-load tap switching device capable of switching the number of taps in approximately the same time.

[Summary of the invention]

In order to achieve the above object, the present invention includes an AC motor that drives an on-load tap changer, a frequency converter that varies the rotation speed of this AC motor, and a rotation detection section that detects the rotation of this AC motor. , an on-load tap switching comprising an arithmetic control circuit that processes the signal output from the rotation detection section and controls ON/OFF of the power switching circuit of the AC motor, and a storage circuit that stores switching data, etc. This device is designed to keep the tap switching time substantially constant by changing the rotation of the AC motor in response to a single tap or continuous tap switching command.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a main part configuration diagram of an on-load tap switching device according to an embodiment of the present invention.

First, the configuration of the on-load tap changer according to the present invention will be explained. Reference numeral 13 is an AC motor that drives the on-load tap changer 1, 14 is a power source for the AC motor 13, and 15 is a switch for switching forward/reverse and stop of the AC motor. A motor power supply switching circuit 16 detects the rotation of the mechanical part driven by the AC motor 13i by optical pulses, positional displacement, etc.; 17 detects the optical pulses detected by the rotation detector, e.g. A pulse generation circuit converts the amount of displacement at a position such as force l- into a pulse of an electrical signal proportional to the rotation speed 1; 18 is an arithmetic control circuit that outputs a signal to control the motor power supply switching circuit 15; 19 is an arithmetic control circuit A storage circuit 18 stores data and programs to be processed, and a display circuit 20 displays tap numbers, switching times, etc., which are the results of calculations and determinations made by the calculation control circuit. 21 is a switching command for one tap or several taps in succession (2) When the arithmetic control circuit 18 determines the switching command and issues a switching command, the frequency is changed again according to the number of switching taps, and the rotational speed of the AC motor is freely controlled. This is a frequency converter for

Next, the operation of the non-embodiment on-load tap switching device configured as described above will be explained with reference to the flowchart of FIG. 2.

When the operation command generation circuit 5 for the tap changer under load outputs the switching operation phalanx of the tap changer under load, the arithmetic circuit 18 determines whether the command is a command to increase the tap voltage or
Determine if it is a command to lower blood pressure.

If the finger % is (1) and the tap is boosted (2), the arithmetic control circuit 18 determines whether the tap position is the maximum tap by counting the pulses from the pulse generation circuit 17.

That is, the % load tap changer 1 is driven by the AC motor 8!13 to change the taps, but the rotation speed of the AC motor 13 at this time is detected by the rotation detection section 16 and converted into pulses via the pulse generation circuit 17. converted. Therefore, the arithmetic control circuit 18 calculates the current position of the on-load tap changer 1 by counting the output pulses from the pulse generation circuit 17, and furthermore, since the maximum tap position is stored in advance in the memory circuit 19 (2), By comparing with this, it is determined whether the maximum tap position has been reached.

As a result, if the maximum tap position has been reached, a limit display is displayed and tap switching is prohibited until a tap step-down command is output from the operation command generation circuit 5. On the other hand, if the maximum tap has not been reached, the arithmetic control circuit 18 outputs a tap boost control signal to the power supply switching circuit 15 of the AC motor [13] to rotate the motor.

Further, if the command is (2), tap step down, the arithmetic control circuit 18 determines whether the tap position is the minimum tap by counting the pulses from the pulse generation circuit 17 (determining from 2. That is, The arithmetic control circuit 18 counts the output pulses from the pulse generation circuit 17 (2), thereby calculating the current position of the load tap changer 1, and calculates the current position of the on-load tap changer 1, and calculates the current position of the tap changer 1 on load, and stores the output pulses in the memory circuit 19 (2).
It is determined whether the minimum tap position has been reached by comparing it with the stored minimum tap. As a result,
If the minimum tap has been reached, a limit display is performed and tap switching is prohibited until a tap boost command is output from the operation command generation circuit 5. If the minimum tap has not been reached, the arithmetic control circuit 18 outputs a tap step-down control signal to the power supply switching circuit 15 of the AC motor 13 to rotate the motor.

Next, the arithmetic control circuit 18 determines whether the tap switching command is a one-tap step-up or step-down signal or a continuous tap switching signal. In the case of the 1-tap switching signal, the arithmetic and control circuit 18 applies a 1-tap switching signal to the power supply switching circuit 15 in response to the step-up or step-down signal, and the AC motor 13 starts the switching operation. At this time, the rotation speed of AC electric e&13 is
Rotation detection section 16. It is converted into a pulse via the pulse generation circuit 17 and input to the arithmetic circuit. The arithmetic control circuit 18 is
These pulses are counted and stored in a memory circuit 19 (=stored).Furthermore, the arithmetic control circuit 18 calculates the count value of the pulse signal corresponding to the rotation speed of the AC motor 13 and the setting value required for l tap switching which is stored in advance in the memory circuit 19. When the on-load tap changer 1 tap change is completed, AC electric [13
The motor is stopped by controlling the power supply switching circuit 15 in the forward or reverse direction so that 18 gives a signal to the power supply switching circuit 15 (=signal), and a signal to vary the frequency is given to the frequency converter 21 that brakes the rotation speed of the AC motor 13, the frequency changes, and the AC motor 13 speeds up and taps are changed. Reduce time. Desired step-up or step-down tap position (same as one-tap switching operation until double is reached (two-fork motor 130 rotation speed is determined by rotation detection unit 16. Pulse generation circuit 17)
The voltage is input to the arithmetic control circuit 18 and controlled, and the step-up or step-down switching operation is completed.

At this time, the frequency is changed and the rotational speed of the current motor 13 is changed in accordance with the number of consecutive tap changes so that the tap change time is the same as the one tap change time (-).

In this way, when the AC motor 13 stops at the normal stop position and a normal tap switching operation is performed, the arithmetic control circuit 18 changes the tap number (21) stored in the memory circuit 19.
Alternatively, the display circuit 20 displays a tap number obtained by adding a number corresponding to the number of consecutive tap changes.

〔Effect of the invention〕

By configuring the on-load tap switching device of the present invention as described above, the following effects can be obtained.

Namely.

(a)? Since the J-mechanical mechanisms such as a step 8M mechanism, a 1-limit stop mechanism, and an indicator mechanism are eliminated, there is no need for complex mechanisms, high-precision machining, or adjustments during component assembly.

(b) Since the rotation detection circuit and arithmetic control circuit that detect the rotation of the AC motor do not use mechanically operating mechanisms, maintenance such as maintenance and inspection due to wear and tear can be reduced.

(c) Conventionally, the completion of tap switching was detected by decelerating the rotation of the electric motor and attaching a cam to the shaft that rotates once per tap switching, but in the present invention, the end of tap switching was detected by decelerating the rotation of the electric motor and attaching a cam to the shaft that rotates once per tap switching. The rotational speed of the driving shaft is detected, the end of tap switching is determined, the power switching circuit is controlled, and the motor stop position at the end of the previous tap switching is corrected to correspond to the mini-minimum value, increasing the accuracy of stop position control. be able to.

(d) Conventionally, when performing continuous switching of several taps, it took several times the preset one-tap switching time. By selecting this, both the one-tap switching time and the several-tap continuous switching time are made substantially constant. As a result, operating efficiency loss can be eliminated, especially when used in electric furnaces and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a tap switching device on load showing an embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation of FIG. 1, and FIG. 3 is a diagram of a conventional tap switching device on load. FIG. 2 is a block configuration diagram.

Claims (1)

[Claims] (1) an AC motor that drives the on-load tap changer; a frequency converter that varies the rotational speed of the AC motor;
A rotation detection section that detects the rotation of the AC motor, an arithmetic control circuit that processes the signal output from the rotation detection section and controls ON/OFF of the power switching circuit of the AC motor, and stores switching data and the like. 1. A tap switching device on load, characterized in that the number of rotations of the AC motor is changed in response to a single tap or continuous tap switching command to keep a tap switching time substantially constant.