JPH0379855B2 - - Google Patents

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 electrically operated operating mechanism for operating a tap changer.

[Technical background of the invention]

In general, tap switching devices under load are equipped with an electric operating mechanism that advances the tap changer in response to voltage fluctuations in the power transmission and distribution system, prohibits stepping outside the switching range, and displays the switching position. However, in the past, most of this electric operation mechanism was constructed mechanically, which made the mechanism complicated, resulting in poor workability during assembly, maintenance, and inspection, as well as being prone to breakdowns and unreliable problems. It was hot.

Therefore, in order to solve this problem, the applicant first proposed a load tap switching device that simplified the mechanism by replacing the mechanical part of the electric operating mechanism with an electric circuit (Japanese Patent Application No. 1983- 28946
(see issue). This will be explained with reference to FIG. In the figure, 1 is a load tap changer, 2 is an electric operating mechanism, 3 is a load of the power transmission and distribution system, 4 is a transformer, and 5
Reference numeral 6 designates an on-load tap-changing device operation command generation circuit, and 6 indicates an on-load tap-changing transformer.

The electric operation mechanism 2 includes a tap changer 1 at the time of load.
An electric motor 7 that generates the power necessary to operate the motor, a rotation detection section 8 that detects the rotation of the mechanical part driven by the electric motor 7 using optical pulses, positional displacement, etc.; A pulse generation circuit 9 that converts optical pulses or the amount of displacement in the position of a cam, etc., into electrical signal pulses proportional to the rotation speed, a motor power supply switching circuit 10 that switches the motor 7 between forward/reverse rotation and stop, and a motor power supply. An arithmetic control circuit 11 that outputs a signal to control the switching circuit 10, a memory circuit 12 that stores data and programs processed by the arithmetic control circuit 11, and tap numbers and switching that are the results of calculations and determinations by the arithmetic control circuit 11. It is composed of a display circuit 13 that displays the number of times and the like.

With the above configuration, when the load 3 fluctuates, the voltage generator 4 captures the fluctuation as a voltage change, and when the amount of change exceeds a certain value, the on-load tap switching device operation command generation circuit 5 issues a switching operation command. emanate. As a result, the arithmetic control circuit 12 first determines whether the command is a tap step-up command or a step-down signal, as shown in the flowchart of FIG. If the command is one tap boost, then the arithmetic control circuit 11 determines whether the tap position is the maximum tap by counting the pulses from the pulse generating circuit 9.

That is, the on-load tap changer 1 is driven by the electric motor 7 to change the taps, and the rotational speed of the electric motor 7 at this time is detected by the rotation detection section 8 and converted into pulses via the pulse generation circuit 9. be done. Therefore, the arithmetic control circuit 11 calculates the current position of the load tap changer 1 by counting the output pulses from the pulse generation circuit 9, and furthermore, the maximum tap position is stored in the memory circuit 12 in advance. Therefore, 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 performed 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 11 outputs a tap boost control signal to the power supply switching circuit 10 of the motor 7, causing the motor 7 to rotate.

As described above, the rotational speed of the electric motor 7 at this time is converted into pulses via the rotation detection section 8 and the pulse generation circuit 9, and the arithmetic control circuit 11 counts these pulses and stores them in the memory circuit 12 as well as the maximum tap position. It is compared with a pre-stored pulse setting value required for one tap change, and it is determined whether the tap change of the on-load tap changer 1 has been completed. When the tap switching of the on-load tap changer is completed, the arithmetic control circuit 11 turns off the tap boost control signal that was output to the power switching circuit 10 of the motor 7, and the motor 7
The rotation of the tap is stopped, the position of the tap is displayed, and the number of times the tap changer 1 is changed under load is displayed, and the one-tap step-up change is completed.

By configuring most of the electric operating mechanism 2 as an electric circuit in this manner, assembly, maintenance and inspection work are facilitated, and a highly reliable on-load tap switching device can be obtained.

[Problems with background technology]

However, in the tap switching device under load, if the contactor, which is the power switching element of the power switching circuit 10, is welded or the thyristor is short-circuited during tap switching, the arithmetic control circuit 11 prevents the tap switching from ending. Even if the determination was made and an OFF signal was issued to the power switching circuit 10, power continued to be supplied to the motor 7, and there was a risk that the motor 7 would run out of control.

[Purpose of the invention]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a highly reliable tap switching device under load that always performs normal tap switching operations without causing the motor to overrun.

[Summary of the invention]

For this reason, the present invention provides a power switching circuit in series with the motor power switching circuit, and if the speed of the motor does not decrease even after the motor power switching circuit is turned off, this power switching circuit is opened. Features.

[Embodiments of the invention]

The present invention will be explained below with reference to the embodiment shown in FIG. In the figure, the same reference numerals as in FIG. 1 indicate the same or corresponding parts, and 14 is a power switching circuit connected to the power supply in series with the power switching circuit 10.

With the above configuration, when the power supply switching circuit 10 is normal, the tap switching operation is performed as described above. However, during the tap switching operation mentioned above,
If the contactor, which is the power switching element of the power switching circuit 10, is welded or the thyristor is shorted, even if the arithmetic control circuit 11 determines that the tap switching is complete and outputs a signal to open the power switching circuit 10,
Power is supplied to the electric motor and the rotation speed does not decrease. Therefore, a phenomenon in which the pulse period corresponding to the rotational speed becomes longer due to deceleration of the electric motor 7, which occurs when normal switching ends, does not occur. The arithmetic control circuit 11 determines that the pulse period does not become longer, opens the power switching circuit 14 of the electric motor 7, and stops the electric motor 7.
Furthermore, the display circuit 1 indicates that the electric motor 7 has started to run out of control.
Display on 3.

〔Effect of the invention〕

As described above, according to the present invention, the electric operation mechanism for driving the on-load tap changer is configured with an electric circuit, which simplifies the mechanism and makes assembly easier.
In addition to improving workability such as maintenance, a power switching circuit is installed in series with the power switching circuit, and after the arithmetic control circuit determines the completion of tap switching and opens the power switching circuit, the pulse period from the rotation detection section is The system monitors the pulse cycle and opens the power supply switching circuit when the pulse period does not become longer, thereby preventing runaway or overrun of the motor and ensuring normal tap switching at all times.This is a highly reliable on-load tap switching device. is obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a load tap switching device previously proposed by the applicant, Fig. 2 is a flowchart for explaining the operation of Fig. 1, and Fig. 3 shows an embodiment of the present invention. FIG. 2 is a block diagram of the main parts of the tap switching device under load. DESCRIPTION OF SYMBOLS 1...Tap changer on load, 2...Electric operation mechanism, 3...Load, 4...Transformer, 5...Tap changer operation command generation circuit on load, 6...Tap changer on load transformer, 7... Electric motor, 8... Rotation detection section, 9... Pulse generation circuit, 10... Motor power supply switching circuit, 11... Arithmetic control circuit, 12... Memory circuit, 13... Display circuit, 14... Power supply Opening/closing circuit.

Claims (1)

[Claims] 1. An electric motor that drives the on-load tap changer, a power switching circuit that switches the rotational direction of this motor and switches on and off the power, a power switching circuit connected in series with this power switching circuit, and a switching circuit for the on-load tap changer. a storage circuit that stores data and drive sequences; a rotation detection unit that detects rotational displacement of the motor; and a pulse generation circuit that generates an electric pulse for each unit rotational displacement detected by the rotation detection unit; The tap switching position obtained by counting the pulses output from the pulse generation circuit is compared with the setting value given from the memory circuit, and the motor is driven and controlled via the power supply switching circuit according to the deviation. After determining that the tap switching is complete and opening the power switching circuit, the pulse cycle from the rotation detection section is monitored, and if the pulse cycle does not become longer, the power switching circuit is opened and the motor is forcibly turned on. An on-load tap switching device characterized by comprising an arithmetic control circuit that causes the tap to stop when the load is applied.