Method for actuating an on-load tap-changer device, and on-load tap-changer device

Abstract

The invention relates to a method for actuating an on-load tap-changer device (50) which comprises an on-load tap changer (1) which comprises a load transfer switch (3) with a second control unit (31), a motor (4) and a control device (6) with a first control unit (62), said method being characterised by the following steps: - in a step (40), a signal for switching the on-load tap-changer (1) is received by the first control unit (62) of the control device (6); - in a step (43), by means of the second control unit (31), a first temperature in or at the on-load tap-changer (1) is determined; - in a step (46), by means of the first control unit (62), one of a plurality of driving profiles (70, 80) for the motor (4) of the on-load tap-changer (1) is selected, said driving profile being based on the first temperature determined by the second control unit (31), on the basis of which a transfer is carried out; and - in a step (47), the transfer is carried out an monitored by means of the motor (5) and the control device (6) according to the selected driving profile (70, 80).

Description

[0001] Method for operating an on-load tap-changer device and on-load tap-changer device. The invention relates to a method for operating an on-load tap-changer device and to an on-load tap-changer device. The on-load tap-changer device comprises at least one on-load tap-changer with a load diverter switch with a second control unit, a motor, and a control device with a first control unit.

[0002] Furthermore, the invention relates to an on-load tap-changer device for carrying out the method according to the invention.

[0003] On-load tap-changers are typically used to regulate voltage in various transformers. Most on-load tap-changers use simple mechanical contacts or vacuum interrupters to perform the switching operations. These on-load tap-changers are operated by a drive system that winds up a spring energy storage device, which ultimately actuates the on-load tap-changer. On-load tap-changers with semiconductor switching elements sometimes no longer require spring energy storage devices, making conventional drive systems unsuitable.

[0004] It is therefore an object of the present invention to provide an improved concept for operating an on-load tap-changer device, by means of which the operation of an on-load tap-changer takes place safely and reliably.

[0005] This object is achieved by a method for actuating an on-load tap-changer device, which comprises the features of claim 1.

[0006] It is a further object of the present invention to provide an on-load tap-changer device by which safety and reliability are increased.

[0007] This object is achieved by a method for actuating an on-load tap-changer device, which comprises the features of claim 10.

[0008] The invention proposes a method for actuating an on-load tap-changer device which comprises an on-load tap-changer which is a load diverter switch with a second control unit, a motor and a control device with a first control unit, characterized by the following steps: in one step, a signal for switching the on-load tap-changer is received from the first control unit of the control device; in one step, the second control unit determines which first temperature is present in or on the on-load tap-changer; in one step, the first control unit selects one of several driving profiles for the motor of the on-load tap-changer, which is based on the first temperature determined by the second control unit, on the basis of which driving profile a switching or actuation is carried out; and in one step, the switching or actuation is carried outActuation is carried out and monitored by means of the motor and the control device according to the selected driving profile.

[0009] The method enables the operation of an on-load tap-changer device, and in particular of the on-load tap-changer, as a function of an external parameter, namely temperature. High temperatures in particular can have a damaging effect on parts of the on-load tap-changer. This applies particularly during switchover, when high currents flow through the on-load tap-changer and its individual components or when high voltages are present at these individual components. Determining the temperature before switchover is used to select an operating profile. At lower temperatures, the on-load tap-changer can be operated normally. At high temperatures, switchovers are carried out more quickly. Due to the faster switchovers, individual components of the on-load tap-changer, in particular individual components of the load diverter switch, in particular the switching elements, in particular the semiconductor switching elements, are loaded for a shorter period of time.This increases the service life of the on-load tap-changer device and thus the service life of the on-load tap-changer.

[0010] The on-load tap-changer device can be designed in any desired manner and can, for example, comprise an on-load tap-changer with a motor and a control device.

[0011] The control device can be configured in any desired manner and, for example, comprise a power supply and / or a first control unit. The first control unit is preferably formed from one or more microcontrollers, each microcontroller having a separate processing unit and a memory. Furthermore, the first control unit can have a first communication element.

[0012] The on-load tap-changer can be designed in any way, for example as an on-load tap-changer with a diverter switch and a selector, or as a load selector. The diverter switch can have mechanical contacts, vacuum interrupters, or semiconductor switching elements (IGBTs, thyristors, etc.). The selector comprises at least one selector arm, whereby the selector arm(s) are driven by a motor and drive shaft through a Geneva gear or planetary gear. The diverter switch and the selector are connected to each other both mechanically and electrically. The selector has two selector arms which, in a stationary state, contact a selector contact and are therefore at the same potential. At the start of operation, one of the selector arms is moved to a second selector contact which is at a different potential than the previous selector contact.This creates a potential difference between the selector arms, which supplies the diverter switch with energy.

[0013] For the purposes of the invention, the term "actuation of an on-load tap-changer device" also includes the actuation of the on-load tap-changer, the implementation of a switchover by the on-load tap-changer from one winding tap n to an adjacent winding tap n+1 of a control winding.

[0014] The on-load tap-changer may also comprise a motor connected to the selector and / or the load diverter switch via a motor shaft and / or drive shaft.

[0015] The signal for switching the on-load tap-changer or for actuating the on-load tap-changer and thus the on-load tap-changer device can preferably be received by the first control device. This signal is preferably generated by a grid measurement controller, a monitoring system, or by manual input (not shown here) and transmitted by these to the first control device.

[0016] After the switching signal, a temperature (second temperature) can preferably be determined using a temperature sensor in the control device. If this temperature is within a predetermined range, the switching is carried out or continued. If it is not within the predetermined range, the switching is aborted. The temperature determined in the control device preferably represents the insulating medium temperature in the transformer.

[0017] The method can be carried out in any way, preferably after the switching signal and after the determination and verification of the temperature in the control device, the selector of the on-load tap-changer is actuated or the selector is actuated up to a certain point so that the load diverter switch is supplied with energy.

[0018] The method can be implemented in any desired manner. Preferably, the selector of the on-load tap-changer is operated to a certain point, so that the diverter switch is supplied with energy through a potential difference in the selector, such that a first selector arm contacts a first selector contact and a second selector arm contacts a second selector contact. The respective selector contacts are connected to corresponding winding taps of a control winding. This creates a potential difference between the selector arms, which serves to supply energy to the diverter switch.

[0019] The method can be carried out in any desired manner; preferably, the second control unit determines the temperature (first temperature) present or prevailing in or at the on-load tap-changer, in particular in or at the diverter switch. This first temperature represents the temperature of the insulating medium in the transformer, since the on-load tap-changer and in particular the diverter switch are arranged in or surrounded by the insulating medium.

[0020] The method can be carried out in any desired manner; preferably, the second control unit also selects an identifier based on the first temperature determined by the second control unit. Preferably, a first identifier A corresponds to a temperature from a temperature range of less than or equal to 100° Celsius (<=100°C). Preferably, a second identifier B corresponds to a temperature from a temperature range of greater than 100° Celsius (<100°C).

[0021] The method can be implemented in any desired manner; preferably, after the identifier has been selected, pause times are adjusted in the second control device of the diverter switch. These pause times determine when the semiconductor switching elements of the diverter switch are actuated. The pause times depend on the previously determined identifier.

[0022] The method can be carried out in any desired manner; preferably, the identifier determined by the second control unit is transmitted or communicated to the first control unit of the control device. The transmission preferably takes place via a first communication element, an optical fiber, and a second communication element.

[0023] The process can be implemented in any way; preferably, the driving profile is selected based on the transmitted identifier. Since the identifier corresponds to a specific temperature or a temperature within a specific temperature range, the driving profile meets the requirements of the temperature range.

[0024] The invention further proposes an on-load tap-changer device with an on-load tap-changer and a control device for carrying out a switchover, wherein the on-load tap-changer is actuated by means of a motor and a control device; the control device has a first control unit which is designed and configured to receive a signal for switching the on-load tap-changer; the on-load tap-changer has a load diverter switch with a second control unit which is designed and configured to determine a temperature in or on the on-load tap-changer; the first control unit is designed and configured to select one of several driving profiles for the motor of the on-load tap-changer, which is based on the temperature determined by the second control unit; the control device is designed and configured to carry out and monitor the switchover by means of the motor according to the selected driving profile.

[0025] The invention and its advantages are explained in more detail below with reference to the attached schematic drawings. They show:

[0026] Figure 1 shows an on-load tap-changer device with a transformer;

[0027] Figure 2 is a detailed schematic representation of the on-load tap-changer device;

[0028] Figure 3 shows a method sequence for operating an on-load tap-changer device;

[0029] Figure 4a shows a possible driving profile;

[0030] Figure 4b shows another possible driving profile.

[0031] Figure 1 shows a schematic structure of the interaction of an on-load tap-changer device 50 with the taps Ni, Nj,..., N Na control winding 20 of a transformer 10. The on-load tap-changer device 50 comprises an on-load tap-changer 1 which, among other things, has a selector 2 and a diverter switch 3. A motor 4 is provided to drive the selector 2 and the diverter switch 3, which motor acts on the selector 2 and thus on the diverter switch 3. Via a motor shaft 5, the motor 4 acts on the on-load tap-changer 1, in particular the selector 2, in order to switch in an upward direction N+ from one tap Nj to the next higher tap N J+ior in a downward direction N- from a tap Nj to the next lower tap Nj.i of the control winding 20 of the transformer 10. While the selector 2 is operated mechanically, the load diverter switch 3 is operated fully electronically. Furthermore, the on-load tap-changer 1 is connected to a control device 6, which is part of the on-load tap-changer device 50. The control device 6 is connected to the motor 4 and the load diverter switch 3. The transformer 10 is filled with an insulating medium, i.e., the on-load tap-changer 1 and the control winding 20 are arranged in the insulating medium (insulating oil). The motor 4 is preferably designed as a stepper motor. Figure 2 shows a detailed schematic representation of the on-load tap-changer device 50, which comprises the on-load tap-changer 1 and the control device 6. A motor 4 in the on-load tap-changer 1 is connected to the selector 2 of the on-load tap-changer 1 via the motor shaft 5.The control device 6 comprises a power supply 61, which contains, for example, an AC / DC or DC / DC converter or a driver circuit (with a stepper motor driver for the controlled or regulated activation of the motor) for the controlled or regulated power supply of the motor 4. A first control unit 62 is connected to control the power supply 61, for example, via a bus. The first control unit 62 is preferably formed from one or more microcontrollers, wherein each microcontroller can have a separate computing unit and a memory. Preferably, the first control unit 62 has a network measurement controller, a drive controller, and a communication controller, each of which has a microcontroller, a separate computing unit, and a memory.

[0032] The control device 6 has a sensor system (not shown here), which serves as a feedback system or is part of the feedback system and is connected to the control device 6 or the first control unit 62. Furthermore, the sensor system is directly or indirectly coupled to the motor shaft or motor 4 (not shown). The motor shaft can be directly connected to the drive shaft 5. Alternatively, the motor shaft corresponds to the drive shaft 5.

[0033] The control device 6, in particular the first control unit 62, is designed and configured to detect and monitor the voltages and / or currents present at the transformer 10, calculate aggregated values, and specify, through switching commands, when the on-load tap-changer device 50 is to be actuated. The grid measurement controller of the first control unit 62 can preferably be used for this purpose.

[0034] The encoder system is configured to detect at least a first value for a position, in particular an angular position, for example, an absolute angular position, of the motor shaft. For this purpose, the encoder system can comprise, for example, a Hall sensor and a magnet. The magnet is attached to the motor shaft or another shaft whose position is uniquely linked to the absolute position of the motor shaft, and the Hall sensor determines or monitors the position of the magnet.

[0035] The control device 6 is configured and designed to control or regulate the motor 4 based on the monitored voltage or the monitored voltage and current or an external specification. Furthermore, the control device 6, in particular the first control unit 62, has a first communication element 63, which is designed as a phototransistor or photoreceiver. Furthermore, the control device 6 can have an energy storage device, for example, supercapacitors. The energy storage device, in conjunction with the power supply 61, provides the energy required to operate the on-load tap-changer 1.

[0036] In the first control unit 62, in particular in a memory or a memory of a microcontroller, in particular in the memory of the drive controller, several driving profiles 70, 80 are stored, among other things. The encoder system, which serves as a feedback system, reports the position of the motor shaft 5 to the first control unit 62 and thus monitors whether the motor shaft 5 is correctly following the selected driving profile 70, 80 or is maintaining the specified parameters.

[0037] One of the driving profiles 70, 80 is selected via the first control unit 62 using the method described in Figure 3 for simultaneous actuation of the selector 2 and the load changeover switch 3.

[0038] Furthermore, the first control unit 62, in particular the grid measurement controller, stores the currents and voltages recorded on and in the transformer 10 during operation. This data is known as historical data and is used to evaluate current and voltage curves.

[0039] The control device 6 has a temperature sensor 64, which is connected to the first control unit 62 or is part of the control unit 62. This sensor determines the temperature of the control device 6. This sensor is preferably arranged in close proximity to the motor 4, i.e., the insulating medium in which the on-load tap-changer 1 is arranged.

[0040] The load diverter switch 3 is used to carry out the actual load switching under load. For this purpose, the load diverter switch 3 comprises a second control unit 31, several semiconductor switching elements, varistors, and a second communication element 32. The second control unit 31 is preferably designed as a microcontroller and, in addition to a computing unit, also has a memory. Furthermore, the second control unit 31 can be designed and configured to determine its own temperature and thus the first temperature of the load diverter switch 3. Alternatively, the load diverter switch 3 can have a temperature sensor with which the first temperature of the load diverter switch 3 can be determined. For both embodiments, it is assumed that the first temperature of the load diverter switch 3 corresponds to the temperature of the transformer 10 filled with insulating medium. The second communication element 32 is designed as a photodiode.An optical fiber 8 connects the first communication element 63 of the control device 6, i.e. the first control unit 62, with the second communication element 32 of the second control unit 31. The semiconductor switching elements of the load changeover switch 3 comprise semiconductor switching elements such as IGBTs, driver circuits and rectifiers.

[0041] Figure 3 shows a method sequence for operating an on-load tap-changer device 50, in particular the implementation of a switchover of the on-load tap-changer 1 with the motor 4 by the control device 6. In the first step 40, a signal for "switching" is first sent to the control device 6. The first control unit 62 of the first control device 6 receives a signal for switching the on-load tap-changer 1. This signal is generated by a grid measurement controller, a monitoring system, or by manual input (not shown here).

[0042] This means that the on-load tap-changer 1 of the on-load tap-changer device 50 must, for example, be operated to adjust the output voltage of the transformer 10 (see Figure 1). However, adjustment runs during maintenance are also conceivable, i.e., operating the on-load tap-changer 1 during service operation.

[0043] In the next step 41, the current temperature of the control device 6, i.e., the temperature at or in the on-load tap-changer 1, is checked via a temperature sensor 64 in the control device 6. This temperature represents the insulating medium temperature in the transformer 10. If this temperature is not within a valid range, such as higher than -40°C, alternatively -25°C, or lower than +120°C, the switchover is aborted. If the measured temperature is within a specified or valid range, the process continues with the next step 42.

[0044] In the next step 42, part of the actuation of the on-load tap-changer 1 takes place. In this case, the selector 2 is actuated by means of the motor 4 and the drive shaft 5 up to a certain point until the diverter switch 3 is supplied with energy or an operating voltage is applied. The drive shaft 5 is preferably rotated by 70°. The selector 2 has two selector arms which, in the stationary state, contact a selector contact and are therefore at the same potential. At the beginning of the actuation, one of the selector arms is moved to a second selector contact which is at a different potential than the previous selector contact. This creates a potential difference between the selector arms, whereby the diverter switch 3 is supplied with energy.

[0045] In the next step 43, the second control unit 32 then determines or measures the temperature on or in the on-load tap-changer 1, in particular in or on the diverter switch 3. For this purpose, the second control unit 32 may have an integrated or separately formed temperature sensor. Based on the determined first temperature, one of two identifiers A, B is selected in the next step 44 in the second control unit 32. The first identifier A corresponds to a temperature within a temperature range of less than or equal to 100° Celsius (<=100°C). The second identifier B corresponds to a temperature within a temperature range of greater than 100° Celsius (<100°C).

[0046] In a next step 45, the corresponding identifier A or B is transmitted to the first communication element 63 of the first control unit 61 by means of the second communication element 32 and the optical fiber 8.

[0047] In the first control unit 61 of the control device 6, a corresponding driving profile 70, 80 is then selected in the next step 46 based on the transmitted identifier A, B. Using this driving profile 70, 80, the further actuation of the on-load tap-changer 1 is carried out or continued and monitored in step 47. In the solution described here, two identifiers A and B and, accordingly, two driving profiles 70 and 80 are used. When carrying out the actuation of the on-load tap-changer device 50, the control unit 6 controls the motor 4, which acts on the selector 2 and the load diverter switch 3 of the on-load tap-changer 1 via the drive shaft 5.

[0048] Parallel to step 44 or immediately thereafter, the sequence of the semiconductor switching elements to be actuated in the load diverter switch 3 is shortened or extended based on the determined identifier A or B by changing at least one waiting time in the switching sequence accordingly, ie shortening or extending it.

[0049] During steps 43 to 46, neither selector 2 nor diverter switch 3 are actuated by motor 4, i.e., motor 4 is stationary and does not drive any motor shaft or drive shaft. Alternatively, steps 43 to 46 can be performed while drive shaft 5 is rotated within a range of 70° - 90°. A 360° rotation of the drive shaft results in complete actuation or switching of the on-load tap-changer or the on-load tap-changer device.

[0050] This simplified method allows the on-load tap-changer 1 or the on-load tap-changer device 50 to be operated with only two operating profiles 70, 80. Different operating profiles 70, 80 are primarily necessary to load the semiconductor switching elements in the diverter switch 3 for a shorter period of time at high temperatures in the transformer. This extends the service life of the semiconductor switching elements and thus that of the entire on-load tap-changer device 50.

[0051] Figures 4a and 4b show possible driving profiles 70, 80 of the motor 4 after a selection based on the identifiers A and B, which were determined by the first temperature in the diverter switch 3. Time is plotted on the x-axis and speed V on the y-axis. The first driving profile 70 is used in a temperature range of less than or equal to 100° Celsius (<=100°C), and the second driving profile 80 is used in a temperature range greater than 100° Celsius (<100°C). The second driving profile 80 has significantly steeper flanks, i.e., the motor 4 is accelerated significantly more strongly until it reaches the target speed. The switching in the second driving profile 80 is completed significantly faster than in the first driving profile, preferably by up to 0.15 seconds. Thus, the duration or running time of the first driving profile 70 is longer than that of the second driving profile 80.Semiconductor switching elements in the diverter switch 3 are thus loaded for a much shorter time, which is particularly advantageous at particularly high temperatures in the insulating medium.

[0052] Reference symbol

[0053] 1 on-load tap-changer

[0054] 2 voters

[0055] 3 load changeover switches

[0056] 4 Engine

[0057] 5 Drive shaft

[0058] 6 Control device

[0059] 8 optical fibers

[0060] 10 Transformer

[0061] 20 control winding

[0062] 31 second control unit

[0063] 32 second communication element

[0064] 50 On-load tap-changer device

[0065] 61 power supply

[0066] 62 first control unit

[0067] 63 first communication element

[0068] 64 Temperature sensor

[0069] 70 first driving profile

[0070] 80 second driving profile

[0071] N+ Upward direction

[0072] N- downward direction Ni, N2,...,N N tapping

[0073] T Time

[0074] V speed

Claims

Patent claims 1. A method for operating an on-load tap-changer device (50) comprising an on-load tap-changer (1) comprising a load diverter switch (3) with a second control unit (31), a motor (4), and a control device (6) with a first control unit (62), characterized by the following steps: in a step (40), a signal for switching the on-load tap-changer (1) is received from the first control unit (62) of the control device (6); in a step (43), a first temperature in or on the on-load tap-changer (1) is determined by means of the second control unit (31); in a step (46), one of several driving profiles (70, 80) for the motor (4) of the on-load tap-changer (1) is selected by means of the first control unit (62), which driving profile is based on the first temperature determined by the second control unit (31), on the basis of which driving profile a switching is carried out;and that in a step (47) the switching is carried out and monitored by means of the motor (5) and the control device (6) according to the selected driving profile (70, 80); 2. Method for operating an on-load tap-changer device (50) according to claim 1, wherein in a step (41) a second temperature is determined by means of a temperature sensor (64) in the control device (6) and if this temperature is within a predetermined range, the switching is carried out, and if this temperature is not within the predetermined range, the switching is aborted.

3. A method for operating an on-load tap-changer device (50) according to any one of claims 1 to 2, wherein in a step (42) a selector (2) of the on-load tap-changer (1) is operated to a certain point so that the load diverter switch (3) is supplied with energy by a potential difference in the selector.

4. A method for operating an on-load tap-changer device (50) according to one of claims 1 to 3, wherein in a step (44) an identifier (A, B) is selected by the second control unit (31) on the basis of the first temperature determined by the second control unit (31).

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

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

7. Method for actuating an on-load tap-changer device (50) according to one of claims 1 to 6, wherein in a step (46) the selection of the driving profile (70, 80) is carried out by the first control unit (62) on the basis of the transmitted identifier (A, B).

8. A method for operating an on-load tap-changer device (50) according to one of claims 1 to 7, wherein the motor (4) is not operated during the determination of the first temperature in or on the on-load tap-changer (1), the selection and transmission of an identifier (A, B) and the selection of the driving profile (70, 80).

9. Method for actuating an on-load tap-changer device (50) according to one of claims 1 to 7, wherein during the determination of the first temperature in or on the on-load tap-changer (1), the selection and transmission of an identifier (A, B) and the selection of the driving profile (70, 80), the motor (4) is actuated such that the drive shaft (5) performs a rotation of 70° to 90°.

10. On-load tap-changer device (50) with an on-load tap-changer (1) and a control device (6) for carrying out a switchover, wherein the on-load tap-changer (1) is actuated by means of a motor (4) and a control device (6); the control device (6) has a first control unit (62) which is designed and configured to receive a signal for switching the on-load tap-changer (1); the on-load tap-changer (1) has a load diverter switch (3) with a second control unit (31) which is designed and configured to determine a first temperature in or on the on-load tap-changer (1); the first control unit (62) is designed and configured to select one of several driving profiles for the motor (4) of the on-load tap-changer (1), which is based on the first temperature determined by the second control unit (31); the control device (6) is designed and configured to carry out and monitor the switching by means of the motor (4) according to the selected driving profile.

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