Method for operating an on-load tap changer and on-load tap changer

Abstract

A method for operating an on-load tap changer 50, which includes an on-load tap changer 1, a changeover switch 3 having a second control unit 31, a motor 4, and a control device 6 having a first control unit 62, wherein the following: - Step 40, in which a signal for switching the under-load tap changer 1 is received by the first control unit 62 of the control device 6, - Step 43, in which the first temperature of the under-load tap changer 1 is measured by the second control unit 31, - Step 46: Of the multiple drive profiles 70, 80 for the motor 4 of the on-load tap changer 1, one drive profile based on the first temperature measured by the second control unit 31 is selected by the first control unit 62, and switching is performed based on this drive profile. - The switching is performed and monitored by the motor 5 and the control device 6 according to the selected drive profiles 70, 80 in step 47, A method for operating a load-operated tap changer 50 characterized by the above.

Description

Technical Field

[0001] The present invention relates to a method for operating a load tap changer and a load tap changer. The load tap changer includes at least one load tap changer having a switching disconnector with a second control unit, a motor, and a control device having a first control unit.

[0002] Furthermore, the present invention relates to a load tap changer for executing the method of the present invention.

Background Art

[0003] Generally, load tap changers are used to control voltages in different transformers. In this case, many load tap changers use simple mechanical contacts or vacuum interrupters for switching. A drive system is used to operate these load tap changers. This drive system winds up an elastic energy storage device, which ultimately operates the load tap changer. On the other hand, load tap changers having semiconductor switch elements no longer require an elastic energy storage device, so the conventional drive system is not suitable.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, an object of the present invention is to provide an improved concept for operating a load tap changer in which the operation of the load tap changer is performed safely and reliably.

Means for Solving the Problems

[0005] This problem is solved by a method for operating a load tap changer including the features described in claim 1.

[0006] A further object of the present invention is to provide a load tap changer with improved safety and reliability.

[0007] This problem is solved by a method for operating an on-load tap changer having the features described in claim 10.

[0008] The present invention is as follows: - The first control unit of the control device receives a signal to switch the tap changer under load, - The second control unit measures the first temperature in the under-load tap changer, -A step in which, from among multiple drive profiles for the motor of the on-load tap changer, one drive profile based on a first temperature measured by the second control unit is selected by the first control unit, and switching is performed based on this drive profile, - The switching or operation is performed and monitored by the motor and control device according to the selected drive profile, Characterized by, We propose a method for operating an on-load tap changing device that includes an on-load tap changer, a changeover switch having a second control unit, a motor, and a control device having a first control unit.

[0009] This method enables the operation of on-load tap changers, particularly on-load tap changers, in a manner dependent on an external parameter, namely temperature. High temperatures, in particular, can have detrimental effects on the components of an on-load tap changer. These detrimental effects occur especially when large currents are energized through the on-load tap changer and its individual components, or when high voltages are applied to these components. Temperature measurement before switching is performed to select a drive profile. At lower temperatures, the on-load tap changer can operate normally. At higher temperatures, switching is performed more rapidly. This faster switching applies the load to the individual components of the on-load tap changer, particularly the individual components of the switching switch, especially the switching elements, and especially the semiconductor switching elements, for a shorter period of time. This extends the lifespan of the on-load tap changer, and consequently, the lifespan of the on-load tap changer.

[0010] The on-load tap changing device can be configured as desired and may include, for example, a changeover switch having a motor and a control device.

[0011] The control device can be configured as desired and may include, for example, a power supply and / or a first control unit. Preferably, the first control unit consists of one or more microcontrollers. In this case, each microcontroller may have a separate arithmetic unit and memory unit. Furthermore, the first control unit may have a first communication element.

[0012] An on-load tap changer can be configured as any configuration, for example, as an on-load tap changer having a changeover switch and a selector, or as a load tap selector. The changeover switch may have mechanical contacts, vacuum circuit breakers, or semiconductor switching elements (IGBTs, thyristors, etc.). The selector includes at least one selector arm. In this case, the selector arm is driven by a motor and drive shaft via a Geneva mechanism or a planetary gear mechanism. The changeover switch and the selector are electrically conductively connected to each other. The selector has two selector arms. In a steady state, these selector arms are in contact with one selector contact and are at the same potential. At the start of operation, one of these selector arms moves to a second selector contact that is at a different potential than the preceding selector contact. Thus, a potential difference is generated between the selector arms. This supplies power (energy) to the changeover switch.

[0013] According to the present invention, the expression "operation of the on-load tap changer" also means the operation of the on-load tap changer, and means switching from winding tap n of the control winding to the adjacent winding tap n+1 by the on-load tap changer.

[0014] Furthermore, the on-load tap changer may have a motor. This motor is connected to the selector and / or changeover switch via a motor shaft and / or drive shaft.

[0015] Preferably, a signal for switching an on-load tap changer or a signal for operating the on-load tap changer, and by extension the on-load tap changer device, can be received by the first control device. Preferably, this signal is generated by a power grid measurement controller, a monitoring system, or (not shown here) manual input, and transmitted to the first control device by these means.

[0016] In accordance with the switching signal, preferably, the temperature (second temperature) is measured by a temperature sensor in the control device. When this second temperature is within a predetermined range, the switching is performed, and when this second temperature is outside the predetermined range, the switching is canceled. Preferably, the temperature measured by the control device represents the temperature of the insulating medium in the transformer.

[0017] This method can be performed as needed, and preferably, in accordance with a switching signal, and in accordance with temperature measurement and inspection within the control device, the selector of the on-load tap changer is operated, or the selector is operated to a predetermined position. As a result, power is supplied to the switching switch.

[0018] This method can be performed optionally, and preferably, when the selector of the under-load tap changer is operated to a predetermined position, power (energy) is supplied to the changeover switch by a potential difference in the selector. As a result, the first selector arm contacts the first selector contact, and the second selector arm contacts the second selector contact. Each selector contact is connected to the corresponding winding tap of the control winding. This generates a potential difference between the selector arms that is used to supply power to the changeover switch.

[0019] This method can be performed optionally, and preferably by using a second control unit, the temperature (first temperature) of the on-load tap changer, particularly the switching device, can be measured. This first temperature reflects the temperature of the insulating medium inside the transformer, because the on-load tap changer, particularly the switching device, is located in or surrounded by the insulating medium.

[0020] This method can be executed optionally, and preferably, by using the second control unit as well, the identifier can be selected based on the first temperature measured by the second control unit. Preferably, the first identifier A corresponds to a temperature within a temperature range of 100 °C or less (≦ 100 °C). Preferably, the second identifier B corresponds to a temperature within a temperature range exceeding 100 °C (> 100 °C).

[0021] This method can be executed optionally, and preferably, in accordance with the selection of the identifier, the rest time in the second control device of the changeover switch is adapted. These rest times define when the semiconductor switching element of the changeover switch is operated. These rest times depend on the previously determined identifier.

[0022] This method can be executed optionally, and preferably, the identifier measured by the second control device can be transmitted or sent to the first control unit of the control device. Preferably, this transmission is executed via the first communication element, the optical fiber, and the second communication element.

[0023] This method can be executed optionally, and preferably, the selection of the profile can be executed based on the transmitted identifier. Since the identifier corresponds to a predetermined temperature or a temperature within a predetermined temperature range, the profile corresponds to the conditions of that temperature range.

[0024] Furthermore, the present invention proposes a load tap changer device having a load tap changer and a control device for executing switching. In this case, the load tap changer is operated by a motor and a control device, the control device has a first control unit, and this first control unit is configured and set to receive a signal for switching the load tap changer, the load tap changer includes a changeover switch having a second control unit, and this second control unit is configured and set to measure the first temperature in the load tap changer, The first control unit is configured and set to select one of several drive profiles for the motor of the on-load tap changer based on a first temperature measured by the second control unit. The control device is configured and set to perform and monitor the switching by the motor according to the selected drive profile.

[0025] The present invention and its advantages will be described in detail below with reference to the attached schematic diagrams. [Brief explanation of the drawing]

[0026] [Figure 1] This shows an on-load tap changing device with a transformer. [Figure 2] This is a detailed schematic diagram of an on-load tap changing device. [Figure 3] This document describes the method and procedure for operating a tap changer under load. [Figure 4a] This shows possible drive profiles. [Figure 4b] Here is another possible program. [Modes for carrying out the invention]

[0027] Figure 1 shows the taps N1, N2, ..., N of the control winding 20 of the transformer 10 and the on-load tap changer 50. N The configuration in which these components cooperate is schematically shown. The on-load tap changer 50 includes an on-load tap changer 1 having a selector 2 and a changeover switch 3. A motor 4 is provided to drive the selector 2 and the changeover switch 3. The motor 4 acts on the selector 2 and, consequently, the changeover switch 3. The control winding 20 of the transformer 10 is tapped N in the boost direction N+. j From the next higher tap N j+1 To switch to or tap N in the step-down direction N- j From the next lower tap N j-1To switch, the motor 4 acts on the on-load tap changer 1, specifically the selector 2, via the motor shaft 5. The selector 2 is operated mechanically, while the changeover switch 3 is operated entirely electronically. Furthermore, the on-load tap changer 1 is connected to a control device 6, which is part of the on-load tap changing device 50. The control device 6 is connected to the motor 4 and the changeover switch 3. The transformer 10 is filled with an insulating medium; that is, the on-load tap changer 1 and the control winding 20 are placed in an insulating medium (insulating oil). Preferably, the motor 4 is configured as a stepping motor.

[0028] Figure 2 is a detailed schematic diagram of an on-load tap changer 50, including an on-load tap changer 1 and a control device 6. A motor 4 in the on-load tap changer 1 is connected to a selector 2 of the on-load tap changer 1 via a motor shaft 5. The control device 6 includes a power supply 61. For open-loop or closed-loop controlled power supply of the motor 4, the power supply 61 includes, for example, an AC / DC converter or a DC / DC converter or a driver circuit (having a stepping motor driver for open-loop or closed-loop controlled power supply of the motor). A first control unit 62 is connected, for example, via a bus, to control the power supply 61. Preferably, the first control unit 62 consists of one or more microcontrollers. In this case, each microcontroller may have a separate arithmetic unit and a memory unit. Preferably, the first control unit 62 has a power grid measurement controller, a drive controller and a communication controller. Each of these controllers has a microcontroller, a separate arithmetic unit and a memory unit.

[0029] The control device 6 has or is part of a sensor system used as a feedback system (not shown) and is connected to the control device 6 or the first control unit 62. Furthermore, this sensor system is directly or indirectly coupled to the motor shaft or motor 4 (not shown). The motor shaft may be directly connected to the drive shaft 5. Alternatively, the motor shaft corresponds to the drive shaft 5.

[0030] The control device 6, particularly the first control unit 62, is configured and set to detect, monitor, and calculate the voltage and / or current applied to the transformer 10, and to instruct, by switching command, when to operate the load tap changer 50. For this reason, the power grid measurement controller of the first control unit 62 may preferably be used.

[0031] The sensor system is configured to detect position, particularly the angular position of the motor shaft, for example, at least one first position value relative to the absolute angular position. For this purpose, the sensor system may include, for example, a Hall sensor and a magnet. In this case, the magnet is fixed to the motor shaft or another shaft (its position is uniquely associated with the absolute position of the motor shaft), and the Hall sensor measures or monitors the position of the magnet.

[0032] The control device 6 is set and configured to control the motor 4 in open-loop or closed-loop mode based on a monitored voltage, or based on a monitored voltage and / or current, or based on an external instruction. Furthermore, the control device 6, in particular the first control unit 62, has a first communication element 63. This first communication element is configured as a phototransistor or optical receiver. Furthermore, the control device 6 may have a power storage device, such as a supercapacitor. The power storage device, connected to the power supply 61, supplies the power necessary to operate the on-load tap changer 1.

[0033] The first control unit 62 stores, in particular, multiple drive profiles 70, 80, especially in the memory or microcontroller memory, and especially in the drive controller memory. The sensor system used as a feedback system notifies the first control unit 62 of the position of the motor shaft 5, thereby monitoring whether the motor shaft 5 is correctly following the selected drive profiles 70, 80 or whether it is complying with predetermined parameters.

[0034] One of the drive profiles 70 and 80 is selected by the first control unit 62 to operate the selector 2 and the changeover switch 3 simultaneously, based on the method shown in Figure 3.

[0035] Furthermore, the first control unit 62, in particular the power grid measurement controller, stores the current and voltage detected by the transformer 10 during operation. This data is so-called historical data and is used to evaluate the trends in current and voltage.

[0036] The control device 6 has a temperature sensor 64. This temperature sensor 64 is connected to or is part of the first control unit 62. The temperature of the control device 6 is measured by this temperature sensor. Preferably, this temperature sensor is located very close to the insulating medium on which the motor 4, i.e., the on-load tap changer 1, is located.

[0037] The load changer 3 is used to actually switch the load when there is load. For this purpose, the changeover switch 3 includes a second control unit 31, a plurality of semiconductor switch elements, a varistor, and a second communication element 32. Preferably, the second control unit 31 is configured as a microcontroller and has memory in addition to an arithmetic unit. Furthermore, the second control unit 31 may be configured and set to measure a specific temperature, namely a first temperature in the changeover switch 3. Alternatively, the changeover switch 3 may have a temperature sensor. The first temperature in the changeover switch 3 may be measured by this temperature sensor. According to both embodiments, the first temperature in the changeover switch 3 is considered to correspond to the temperature of the transformer 10 filled with an insulating medium.

[0038] The second communication element 32 is configured as a photodiode. The optical fiber 8 connects the control device 6, i.e., the first communication element 63 of the first control unit 62, to the second communication element 32 of the second control unit 31. The semiconductor switching elements of the changeover switch 3 include, for example, semiconductor switching elements such as IGBTs, a driver circuit, and a rectifier.

[0039] Figure 3 shows the procedure for operating the on-load tap changer 50, and in particular the procedure for the control device 6 to cause the motor 4 to switch the on-load tap changer 1. In the first step 40, a "switch" signal is first output to the control device 6. The first control unit 62 of the first control device 6 receives the signal to switch the on-load tap changer 1. This signal is generated by a power grid measurement controller or monitoring system, or by manual input (not shown here).

[0040] In other words, the on-load tap changer 1 of the on-load tap changer 50 must be operated, for example, to match the output voltage of the transformer 10 (see Figure 1). However, adjustment drive during maintenance, i.e., operation of the on-load tap changer 1 during maintenance drive, is also possible.

[0041] In the next step 41, the current temperature of the control device 6, i.e., the temperature of the on-load tap changer 1, is checked by the temperature sensor 64 of the control device 6. This temperature represents the temperature of the insulating medium inside the transformer 10. If this temperature is not within the valid range, for example, if it is higher than -40°C or -25°C or lower than +120°C, the switching is aborted. If the measured temperature is within the predetermined range or within the valid range, the process proceeds further in the next step 42.

[0042] In the next step 42, part of the operation of the under-load tap changer 1 is performed. In this case, when power is supplied to the changeover switch 3, or when an operating voltage is applied to the changeover switch 3, the selector 2 is operated to a predetermined position by the motor 4 and the drive shaft 5. In this case, preferably, the drive shaft 5 is rotated by 70°. The selector 2 has two selector arms. In the steady state, these selector arms are in contact with one selector contact and are at the same potential. At the start of operation, one of these selector arms moves to a second selector contact. This second selector contact is at a different potential than the preceding selector contact. Therefore, a potential difference is generated between the selector arms. This supplies power to the changeover switch 3.

[0043] Next, in step 43, the temperature of the under-load tap changer 1, particularly the changeover switch 3, is measured by the second control unit 31. For this purpose, the second control unit 31 may have an integrated temperature sensor or a separately configured temperature sensor. In the next step 44, one of two identifiers A and B is selected by the second control unit 32 based on the measured first temperature. The first identifier A corresponds to a temperature within the temperature range of 100°C or less (≤100°C). The second identifier B corresponds to a temperature within the temperature range of >100°C.

[0044] In the next step 45, the corresponding identifier A or B is transmitted to the first communication element 63 of the first control unit 62 via the second communication element 32 and the optical fiber 8.

[0045] Next, in step 46, the corresponding drive profiles 70, 80 are selected in the first control unit 62 based on the transmitted identifier A, B. In step 47, further operation of the on-load tap changer 1 is performed or continued and monitored by these drive profiles 70, 80. In the solution described herein, two identifiers A and B and two corresponding drive profiles 70 and 80 are used. When performing operation of the on-load tap changer 50, the control device 6 controls the motor 4. This motor 4 acts on the selector 2 and the changeover switch 3 of the on-load tap changer 1 via the drive shaft 5.

[0046] In parallel with or immediately following step 44, the procedure for operating the semiconductor switch element in the changeover switch 3 is shortened or extended based on the identified identifier A or B. In this procedure, at least one waiting time in the changeover procedure is appropriately modified, i.e., shortened or extended.

[0047] During steps 43-46, the selector 2 is not operated by the motor 4, nor is the changeover switch 3 operated. That is, the motor 4 is stopped and does not drive the motor shaft or drive shaft. Alternatively, steps 43-46 may be performed while the drive shaft 5 is rotated within the range of 70° to 90°. When the drive shaft is rotated 360°, the on-load tap changer or on-load tap changer is fully operated or fully switched.

[0048] This simplified method allows the on-load tap changer 1 or on-load tap changer 50 to be operated by only two drive profiles 70 and 80. In particular, the different drive profiles 70 and 80 are necessary to shorten the period during which the semiconductor switch elements of the changeover switch 3 are under load when the temperature inside the transformer is high. This extends the lifespan of the semiconductor switch elements and, consequently, the overall lifespan of the on-load tap changer 50.

[0049] Figures 4a and 4b show the possible drive profiles 70 and 80 of the motor 4 after selection, based on identifiers A and B determined by the first temperature in the changeover switch 3. Time is plotted on the x-axis and speed V is plotted on the y-axis. The first drive profile 70 is used in a temperature range of ≤100°C, and the second drive profile 80 is used in a temperature range of >100°C. The second drive profile 80 has a much steeper rise. That is, the motor 4 is accelerated significantly more strongly until it reaches the target speed. The switching in the second drive profile 80 is completed much faster than the switching in the first drive profile, preferably by up to 0.15 seconds earlier. Therefore, the duration or operating time of the first drive profile 70 is longer than that of the second drive profile 80. Thus, the duration of the load on the semiconductor switching element of the changeover switch 3 is significantly shorter. This is particularly beneficial when the temperature in the insulating medium is very high. [Explanation of Symbols]

[0050] 1. On-load tap changer 2 Selector 3 Switch switch 4 motors 5 Drive shaft 6 Control device 8 optical fibers 10 Transformers 20 Control winding 31 Second Control Unit 32 Second communication element 50 Load switching device 61 Power supply 62 First Control Unit 63. First communication element 64 Temperature Sensors 70 First drive profile 80 Second drive profile N+ Boost Direction N- Step-down direction N1, N2, ..., N N Tap T time V speed

Claims

1. A method for operating an on-load tap changer (50) which includes an on-load tap changer (1) equipped with a changeover switch (3) having a second control unit (31), a motor (4), and a control device (6) having a first control unit (62), wherein the following: - Step (40) in which a signal for switching the on-load tap changer (1) is received by the first control unit (62) of the control device (6), - Step (43) in which the first temperature of the under-load tap changer (1) is measured by the second control unit (31), - Step (46) in which, from among a plurality of drive profiles (70, 80) for the motor (4) of the on-load tap changer (1), one drive profile based on the first temperature measured by the second control unit (31) is selected by the first control unit (62), and switching is performed based on this drive profile, - The switching is performed and monitored by the motor (5) and the control device (6) according to the selected drive profile (70, 80) in step (47), A method for operating an on-load tap changer (50) characterized by the above.

2. A method for operating an on-load tap changer (50) according to claim 1, wherein in step (41), a second temperature is measured by a temperature sensor (64) in the control device (6), switching is performed when the second temperature is within a predetermined range, and switching is canceled when the second temperature is not within a predetermined range.

3. A method for operating an on-load tap changing device (50) according to claim 1 or 2, wherein in step (42), the selector (2) of the on-load tap changer (1) is operated to a predetermined position, and as a result, power is supplied to the changeover switch (3) by the potential difference in the selector.

4. A method for operating an on-load tap changer (50) according to any one of claims 1 to 3, wherein in step (44), identifiers (A, B) are selected by the second control unit (31) based on a first temperature measured by the second control unit (31).

5. A method for operating an on-load tap changer (50) according to any one of claims 1 to 4, wherein in step (45), identifiers (A, B) determined by the second control unit (31) are transmitted to the first control unit (62) by the second control unit (31).

6. A method for operating an on-load tap changer (50) according to claim 5, wherein in step (45), identifiers (A, B) are transmitted by a first communication element (63), an optical fiber (8), and a second communication element (32).

7. A method for operating an on-load tap changer (50) according to any one of claims 1 to 6, wherein in step (46), the selection of drive profiles (70, 80) is performed by a first control unit (62) based on transmitted identifiers (A, B).

8. A method for operating an on-load tap changer according to any one of claims 1 to 7, wherein the motor (4) is not operated while the first temperature is being measured in the on-load tap changer (1), while identifiers (A, B) are being selected and transmitted, and while drive profiles (70, 80) are being selected.

9. A method for operating an on-load tap changer according to any one of claims 1 to 7, wherein the motor (4) is operated so that the drive shaft (5) rotates between 70° and 90° during the measurement of a first temperature in the on-load tap changer (1), the selection and transmission of identifiers (A, B), and the selection of drive profiles (70, 80).

10. An on-load tap changing device (50) having an on-load tap changer (1) and a control device (6) for performing switching, The under-load tap changer (1) is operated by a motor (4) and a control device (6). The control device (6) has a first control unit (62), which is configured and set to receive a signal for switching the on-load tap changer (1). The on-load tap changer (1) comprises a changeover switch (3) having a second control unit (31), and this second control unit (31) is configured and set to measure the first temperature of the on-load tap changer (1). The first control unit (62) is configured and set to select one of a plurality of drive profiles for the motor (4) of the on-load tap changer (1) based on the first temperature measured by the second control unit (31). The control device (6) is configured and set up to perform and monitor the switching by the motor (4) according to the selected drive profile, and is a load-operated tap changer (50).

Images