Electrically operated mechanism and tap changing device for on-load tap changer

Abstract

This invention provides an electrically operated mechanism that allows the output shaft to be rotated using general tools and enables easy tap switching. [Solution] The electric operation mechanism of the on-load tap changer comprises a pulse motor that provides rotational driving force capable of driving the on-load tap changer to an output shaft connected to the on-load tap changer, a motor driver that drives the pulse motor, an excitation current switching switch for switching the supply and interruption of excitation current to the pulse motor, and a control device that interrupts the supply of excitation current from the motor driver to the pulse motor when the excitation current switching switch is operated.

Description

Technical Field

[0001] The present disclosure relates to an electric operating mechanism for a on-load tap-changer and an on-load tap-changer device.

Background Art

[0002] The electric operating mechanism includes an output shaft connected to the on-load tap-changer, an electric motor that applies a rotational driving force to the output shaft via a speed reducer, a handle shaft for manually driving the on-load tap-changer during maintenance and inspection, a manual handle gear mechanism that mechanically connects the handle shaft and the speed reducer, and a control device (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the conventional electric operating mechanism, many components need to be configured for manual handle operation, such as providing a handle shaft and a manual handle gear mechanism in the electric operating mechanism. In addition, since the output shaft is connected to the electric motor via a speed reducer, it is difficult to rotate the output shaft with a general tool.

[0005] An object of the present disclosure is to provide an electric operating mechanism and an on-load tap-changer device that can rotate the output shaft with a general tool such as a wrench or a monkey wrench and can easily perform tap switching.

Means for Solving the Problems

[0006] The electrically operated mechanism for an on-load tap changer of this disclosure comprises a pulse motor that provides a rotational driving force capable of driving the on-load tap changer to an output shaft connected to the on-load tap changer, a motor driver that drives the pulse motor, an excitation current switching switch for switching the supply and interruption of excitation current to the pulse motor, and a control device that interrupts the supply of excitation current from the motor driver to the pulse motor when the excitation current switching switch is operated.

[0007] The on-load tap changer of this disclosure comprises the above-mentioned electric operating mechanism and the on-load tap changer body which is operated by the rotational driving force output from the electric operating mechanism. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an electrically operated mechanism and a tap changing device under load that can rotate the output shaft with a general tool and allow for easy tap switching. [Brief explanation of the drawing]

[0009] [Figure 1] This is a block diagram showing an example configuration of a load-dependent tap-changing device according to this embodiment. [Figure 2] This is a schematic diagram showing the external appearance of the electric operating mechanism. [Figure 3] This is a block diagram showing an example of a control device configuration. [Figure 4] This is a flowchart showing the processing procedure of the control device. [Modes for carrying out the invention]

[0010] An electric operating mechanism and an on-load tap changing device of an on-load tap changer according to the embodiments of this disclosure will be described below with reference to the drawings. This disclosure is not limited to these examples, but is intended to include all modifications within the meaning and scope of the claims, as indicated by the claims. Furthermore, at least some of the embodiments described below may be combined in any way.

[0011] Figure 1 is a block diagram showing an example configuration of the on-load tap changer 101 according to this embodiment, and Figure 2 is a schematic configuration diagram showing the external appearance of the electric operating mechanism 1. The on-load tap changer 101 according to this embodiment comprises an on-load tap changer body (on-load tap changer) 2 and an electric operating mechanism 1 connected to the on-load tap changer body 2 and outputting rotational driving force. The on-load tap changer 101 is connected to the primary winding of a transformer and is a device for adjusting the distribution voltage to an appropriate range by switching the transformation ratio of the transformer. The on-load tap changer body 2 operates by the rotational driving force output from the electric operating mechanism 1 and performs tap changing.

[0012] The electric operating mechanism 1 includes an output shaft 10 connected to the tap changer body 2 under load, a pulse motor 11 that provides rotational driving force to the output shaft 10, a motor driver 12 that drives the pulse motor 11, a control device 13 that controls the motor drive, an excitation current switching switch 14, an up / down switch 15, a tap position indicator 16, a counter 17, and a door switch 18.

[0013] The various components of the electric operating mechanism 1 are housed in a box 1a, which is attached to the tank side wall of the transformer where the load tap changer body 2 is installed. The box 1a has an opening on the front, and a door 1b is supported so that it can be opened and closed. The door 1b is provided with a viewing window 1c so that the tap position indicator 16 and counter 17 can be viewed from outside the box 1a. The box 1a is provided with a door switch 18 which turns on and off in accordance with the opening and closing of the door 1b.

[0014] The drive system and electrical components, such as the pulse motor 11, motor driver 12, and control device 13, housed in the enclosure 1a, are protected by a protective panel 1d located on the front of the enclosure 1a. The protective panel 1d has a rectangular display window that allows the contents of the tap position indicator 16 and counter 17 located inside to be seen. Additionally, an excitation current switching switch 14 and a lifting switch 15 are provided at appropriate locations on the protective panel 1d.

[0015] The output shaft 10 is positioned to protrude upward from a hole formed in the upper surface of the housing 1a and is directly connected to the pulse motor 11 without the need for a gear mechanism such as a reduction gear. The output shaft 10 protruding from the housing 1a is connected to the input shaft 21a of the load tap changer body 2 via a shaft coupling 3.

[0016] The pulse motor 11 is an electric motor that operates using an excitation current supplied from the motor driver 12 and provides rotational driving force to the output shaft 10. The pulse motor 11 has an output capable of driving the tap changer body under load without the need for a reduction gear. The pulse motor 11 is configured to rotate 90 degrees with, for example, 125 pulses, and rotates in increments of 0.72°. Even when the pulse motor 11 is not rotating, an excitation current is supplied from the motor driver 12, and the rotational shaft is not allowed to rotate freely, maintaining its rotational position.

[0017] The pulse motor 11 is equipped with a mechanical absolute encoder 11a that detects the rotational position of the output shaft 10. The absolute encoder 11a comprises, for example, a plurality of gears having a gear ratio that reduces rotation. The first gear is connected to the output shaft 10, and the second gear that meshes with the first gear, the third gear that meshes with the first gear, and so on, rotate at a reduced speed in accordance with the rotation of the output shaft 10. The absolute encoder 11a reads the rotational position of the output shaft 10 by detecting the rotational position of each gear and outputs the read rotational position information to the motor driver 12. The absolute encoder 11a can read a rotational position of, for example, 1800 rpm. The absolute encoder 11a may not be built into the pulse motor 11, but may be configured separately from the pulse motor 11.

[0018] The motor driver 12 has terminals for connecting to the pulse motor 11, an internal communication port for communicating with the control device 13, and an external communication port 12b to which an information and communication terminal 5 such as an external PC can be detachably connected. The motor driver 12 is connected to the pulse motor 11 and the control device 13.

[0019] The motor driver 12 can acquire the rotational position information output from the absolute encoder 11a and recognize the rotational position of the pulse motor 11. The motor driver 12 supplies an exciting current to the pulse motor 11 according to a motor rotation command from a control device 13 described later, and rotates the pulse motor 11.

[0020] Further, the motor driver 12 includes an exciting current off-switch 12a for interrupting the supply of the exciting current to the pulse motor 11 according to a motor rotation command from the control device 13. The exciting current off-switch 12a is composed of a semiconductor switch, a photocoupler, a relay circuit, or the like. When the supply of the exciting current to the pulse motor 11 is interrupted, the output shaft 10 of the pulse motor 11 can rotate freely. Since the output shaft 10 is directly connected to the pulse motor 11 without passing through a speed reducer or the like, the output shaft 10 protruding from the box body 1a can be easily rotated manually using a general tool such as a spanner or a monkey wrench. Note that even when the supply of the exciting current is stopped, the motor driver 12 can acquire the rotational position information output from the pulse motor 11. Therefore, even when the output shaft 10 is rotated manually, the motor driver 12 and the control device 13 always recognize the rotational position of the output shaft 10.

[0021] Note that the motor driver 12 can limit the rotation range of the output shaft 10 of the pulse motor 11. For example, when the load tap changer main body 2 can be switched from the 1st tap to the 17th tap, if the number of steps (number of pulses) of the pulse motor 11 required to raise or lower one tap is 10000 (20 rotations), the motor driver 12 sets the lower limit of the rotational position of the output shaft 10 to 10000 steps and the upper limit to 170000 steps. The motor driver 12 stores data indicating the upper and lower limits of the rotational position of the output shaft 10.

[0022] Furthermore, while the motor driver 12 normally operates according to motor rotation commands from the control device 13, if an information and communication terminal 5 is connected to the external communication port 12b, it can also receive motor rotation commands from the information and communication terminal 5 and drive the pulse motor 11. For example, the information and communication terminal 5 can output a motor rotation command indicating an arbitrary number of steps, rotation position, etc., for the pulse motor 11, and the motor driver 12 rotates the pulse motor 11 according to that motor rotation command. Furthermore, the motor driver 12 has a function to output the rotational position information of the pulse motor 11, read by the absolute encoder 11a, to the information and communication terminal 5. Based on the rotational position information output from the motor driver 12, the information and communication terminal 5 can display the current rotational position of the pulse motor 11, i.e., the number of steps.

[0023] Figure 3 is a block diagram showing an example configuration of the control device 13. The control device 13 is a computer such as a PLC (Programmable Logic Controller) that drives and controls the pulse motor 11 via the motor driver 12, and comprises a control unit 13a, a storage unit 13b, a communication unit 13c, an input unit 13d, an output unit 13e, and a motor control communication unit 13f.

[0024] The control unit 13a is a processor and includes arithmetic processing circuits such as a CPU (Central Processing Unit), multi-core CPU, ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), internal storage devices such as ROM (Read Only Memory) and RAM (Random Access Memory), and I / O terminals. The control unit 13a functions as a control device 13 by executing the control program stored in the storage unit 13b.

[0025] The storage unit 13b includes non-volatile memory such as a hard disk, flash memory, or SSD (Solid State Drive). The storage unit 13b stores control programs, other various programs, and data that are referenced by the control unit 13a.

[0026] The communication unit 13c is a communication circuit that sends and receives information to and from the higher-level control device 4, which commands the tap switching of the load-on tap changer 101, according to a predetermined communication protocol. Under normal conditions, the control device 13 receives the tap switching command transmitted from the higher-level control device 4 and drives the motor driver 12 according to the received tap switching command. Furthermore, if the motor driver 12 has a communication pass-through function, the control device 13 may communicate with the higher-level control device 4 via the motor driver 12.

[0027] The input section 13d is a signal input terminal, and the excitation current switching switch 14, the lifting switch 15, and the door switch 18 are connected to the input section 13d, and signals indicating the status of each switch are input to it. The control unit 13a recognizes the status of each switch via the input section 13d.

[0028] The excitation current switching switch 14 is a switch for switching between supplying excitation current to the pulse motor 11 and cutting off the supply of excitation current. The excitation current switching switch 14 is, for example, a microswitch. The type of excitation current switching switch 14 is not particularly limited.

[0029] The lifting switch 15 is, so to speak, a switch that forcibly drives the pulse motor 11 and operates the tap changer unit under load. During maintenance and inspection in a live state, when the door 1b is opened, the tap changing command from the higher control device 4 is cut off, but by operating the lifting switch 15, the pulse motor 11 can be forcibly driven and tap changing can be performed. The lifting switch 15 is, for example, a microswitch. Note that the type of lifting switch 15 is not particularly limited.

[0030] The door switch 18 is a switch for detecting the open or closed state of the door 1b. When the control device 13 detects that the door 1b is open, it blocks the tap switching command from the higher-level control device 4 to prevent the mechanism inside the box 1a from operating unexpectedly.

[0031] The output section 13e is a signal output terminal, to which the tap position indicator 16 and the counter 17 are connected. The tap position indicator 16 comprises a small stepping motor and a nameplate displaying the tap numbers. The nameplate is, for example, disc-shaped, with all selectable tap numbers displayed along its circumference, and a portion of it visible through the display window of the protective panel 1d. The control device 13 can recognize the rotational position of the pulse motor 11, i.e., the step number, by communicating with the motor driver 12. The control device 13 stores the relationship between the rotational position of the pulse motor 11 and the tap number. The control device 13 also stores the relationship between the rotational position of the stepping motor, where the tap number is visible through the display window of the protection panel 1d, and the tap position. The control device 13 displays the current tap position by controlling the rotation of a small stepping motor to the rotational position corresponding to the rotational position of the pulse motor 11. Furthermore, the control device 13 counts the number of tap changes, and each time a tap change occurs, it drives the counter 17 and increments the count.

[0032] The motor control communication unit 13f is a communication circuit for communicating various information with the motor driver 12. The control device 13 sends and receives information with the motor driver 12 via the motor control communication unit 13f, and recognizes the rotational position of the pulse motor 11, controls the rotational position of the pulse motor 11, and controls the interruption and supply of excitation current to the pulse motor 11.

[0033] Returning to Figure 1, the configuration of the on-load tap changer body 2 will be briefly explained. The on-load tap changer body 2 comprises an input shaft 21a to which the rotational driving force output from the electric operating mechanism 1 is input, an energy storage device 21 and a changeover switch 22 housed in the changeover switch chamber 20, and a tap selector 23.

[0034] The tap selector 23 is equipped with a tap winding. The tap winding is connected to the main winding of the transformer. The tap winding has multiple taps drawn out from multiple locations along the winding. The tap selector 23 is connected to one of the taps selected according to the load on the secondary side of the transformer. The tap selector 23 is operated by a rotational driving force output from the electric operating mechanism 1.

[0035] The changeover switch 22 is a switch that controls the current path when tap switching occurs, and is composed of a current-limiting resistor, a vacuum valve, and a switch, etc.

[0036] The energy storage device 21 stores the rotational driving force output from the electric operating mechanism 1 in a spring, and drives the changeover switch 22 by releasing the stored biasing force.

[0037] The amount of rotation of the output shaft 10 required to perform tap switching by the tap changer body 2 under load is constant, for example, 20 rotations. The rotational position of the output shaft 10 corresponding to the tap switching operation to each tap position, i.e., the number of steps, is determined by the design. For example, when tap 1 is selected, the rotational position of the output shaft 10 is 10,000 steps. The number of steps required to switch from tap 1 to tap 2 is 10,000, and when tap 2 is selected, the rotational position of the output shaft 10 is 20,000 steps. Similarly, for tap 3 it is 30,000 steps, for tap 4 it is 40,000 steps, ... for tap 17 it is 170,000 steps.

[0038] In the tap switching operation, the timing at which the biasing force stored in the energy storage device 21 is released and the current path is switched by the changeover switch 22 (referred to as the activation point) is, for example, 8800 steps from the start of the tap switching operation. For example, the activation point when switching from tap 1 to tap 2 is 18800. After activation, the cam mechanism (not shown) that constitutes the load tap changer body 2 operates for another 1200 steps to complete the tap switching.

[0039] Figure 4 is a flowchart showing the processing procedure of the control device 13. The control device 13 monitors the state of the door switch 18 and determines whether the door 1b is open or closed (step S11). If it is determined that the door 1b is closed (step S11: NO), the control device 13 drives the pulse motor 11 according to the tap switching command from the higher-level control device 4 and controls the tap switching (step S12).

[0040] If the control device 13 determines that door 1b is open (step S11: YES), it blocks the tap switching command from the higher-level control device 4 (step S13). The control device 13 monitors the operating state of the lift switch 15 and determines whether or not the lift switch 15 has been operated (step S14). If it determines that the lift switch 15 has been operated (step S14: YES), the control device 13 drives the pulse motor 11 according to the operation (step S15). If the lift switch 15 is operated in the boost direction, the control device 13 outputs a motor rotation command to the motor driver 12 to increase the voltage by, for example, 10,000 steps, and drives the pulse motor 11 to rotate. If the lift switch 15 is operated in the deflation direction, the control device 13 outputs a motor rotation command to the motor driver 12 to decrease the voltage by, for example, 10,000 steps, and drives the pulse motor 11 to rotate. Note that 10,000 steps is just an example.

[0041] If the control device 13 determines that the lift switch 15 has not been operated (step S14: NO), or after completing the process in step S15, it determines whether or not an excitation-off operation has been performed by operating the excitation current switching switch 14 (step S16). If it determines that an excitation-off operation has been performed (step S16: YES), the control device 13 cuts off the supply of excitation current to the pulse motor 11 by sending an excitation current supply cutoff command to the motor driver 12 (step S17).

[0042] If it is determined that the excitation has not been turned off (step S16: NO), or if the process in step S17 has been completed, the control device 13 determines whether or not the excitation has been turned on by operating the excitation current switching switch 14 (step S18). If it is determined that the excitation has been turned on (step S18: YES), the control device 13 restarts the supply of excitation current to the pulse motor 11 by sending a command to the motor driver 12 to restart the supply of excitation current (step S19).

[0043] If it is determined that the excitation has not been turned on (step S18: NO), or if the processing in step S19 has been completed, the control device 13 obtains rotational position information of the pulse motor 11 from the motor driver 12 (step S20) and determines whether the tap position has changed (step S21). Note that if the excitation current is cut off and the output shaft 10 is rotated manually, the tap position may change even if the control device 13 is not performing tap switching control. If it is determined that the tap position has not changed (step S21: NO), the control device 13 returns to step S11. If it is determined that the tap position has changed (step S21: YES), the display content of the tap position indicator 16 is changed (step S22), and the process returns to step 11.

[0044] As described above, with the electric operating mechanism 1 and on-load tap changer according to this embodiment, the excitation current to the pulse motor 11 can be cut off by opening the door 1b and operating the excitation current changeover switch 14. Since the output shaft 10 is connected to the on-load tap changer body without going through a reduction gear, the output shaft 10 becomes freely rotatable when the excitation current is cut off. Therefore, the tap can be easily changed by directly operating the output shaft 10 with a general tool such as a spanner or monkey wrench. By omitting the manual handle mechanism in the electric operating mechanism 1, the device can be made smaller, lighter, reduce environmental impact, and contribute to cost reduction.

[0045] Furthermore, since the rotational position of the pulse motor 11 is managed by the absolute encoder 11a, tap position control is not affected even if the output shaft 10 is operated manually. When tap position switching control by the control device 13 is resumed, the control device 13 acquires rotational position information indicating the absolute rotational position of the pulse motor 11 read by the absolute encoder 11a and can execute tap position switching control. For example, even if the rotational position of the pulse motor 11 is at 12,000 steps as a result of manual operation, when the control device 13 performs a tap switch to tap number 2, it can rotate the pulse motor 11 to a rotational position of 20,000 steps and switch the tap position normally.

[0046] Furthermore, since the rotational position of the pulse motor 11 is managed by the absolute encoder 11a even when the excitation current is interrupted, the control device 13 can switch the display of the tap position even if the tap position is switched by manually rotating the output shaft 10.

[0047] Furthermore, if a door switch 18 or the like is provided, it can detect the opening and closing of the door 1b, and if the door 1b is opened, it can cut off the tap switching command from the higher-level control device 4, thus allowing for safe maintenance and inspection of the electric operating mechanism 1. Of course, the electric operating mechanism 1 may also be configured without a door switch 18.

[0048] Furthermore, the tap position can be forcibly changed by operating the height adjustment switch 15.

[0049] Furthermore, by connecting an information and communication terminal 5 to the electric operating mechanism 1 and outputting a motor rotation command to the motor driver 12, the pulse motor 11 can be rotated by any amount. In other words, the output shaft 10 can be rotated using an information and communication terminal 5 such as a general-purpose PC instead of a conventional tool. It is also possible to display the rotation position of the pulse motor 11 on the information and communication terminal 5. [Explanation of symbols]

[0050] 1: Electric operating mechanism, 2: On-load tap changer body, 10: Output shaft, 11: Pulse motor, 11a: Absolute encoder, 12: Motor driver, 12a: Excitation current off switch, 12b: External communication port, 13: Control device, 14: Excitation current changeover switch, 15: Lift / lower switch, 16: Tap position indicator, 17: Counter, 18: Door switch, 101: On-load tap changer

Claims

1. A pulse motor provides rotational driving force capable of driving the on-load tap changer to an output shaft connected to the on-load tap changer, A motor driver that drives the pulse motor, An excitation current switching switch for switching the supply and interruption of excitation current to the pulse motor, When the excitation current switching switch is operated, a control device interrupts the supply of excitation current from the motor driver to the pulse motor. An electric operating mechanism for an on-load tap changer.

2. The system includes a mechanical absolute encoder for detecting the rotational position of the pulse motor, The control device is Even if the excitation current to the pulse motor is interrupted, the absolute encoder acquires the rotational position information of the pulse motor. Manage tap locations The electric operating mechanism according to claim 1.

3. It is equipped with a tap position indicator that displays tap position information corresponding to the acquired rotational position information. The electric operating mechanism according to claim 2.

4. The pulse motor, the motor driver, the excitation current switching switch, and the control device are housed in a box with an openable and closable door. Equipped with a door switch that detects the opening and closing of the door, The control device is When the door switch detects that the door is open, it blocks the command for driving the pulse motor transmitted from the higher-level control device. The electric operating mechanism according to claim 1.

5. The aforementioned under load tap changer is equipped with an up / down switch for changing the tap position, The control device is When the lifting switch is operated, a command indicating the rotational position of the pulse motor necessary to increase or decrease the tap position is sent to the motor driver. The electric operating mechanism according to claim 2.

6. An electric operating mechanism according to any one of claims 1 to 5, The on-load tap changer body is operated by the rotational driving force output from the electric operating mechanism and A tap changer that is equipped with an on-load tap changer.

Images