Patent Publication Number: US-2022216014-A1

Title: Switch assembly with drive system and method for driving a switch

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Phase application under 35 U.S.C. § 371 of International Application No. PCT/EP2020/061276, filed on Apr. 23, 2020, and claims benefit to German Patent Application No. DE 10 2019 112 711.4, filed on May 15, 2019. The International Application was published in German on Nov. 19, 2020, as WO 2020/229120 A1 under PCT Article 21(2). 
    
    
     FIELD 
     The invention relates to a switch assembly having a switch and a drive system for the switch, and also to a method for driving a switch. 
     BACKGROUND 
     In substations, there are a large number of switches for different tasks and with different requirements. To operate the various switches, they must be driven via a drive system. These switches include, amongst others, on-load tap-changers, diverter switches, selectors, double reversing change-over selectors, reversing change-over selectors, change-over selectors, circuit breakers, on-load switches or disconnecting switches. 
     For example, on-load tap-changers are used for uninterrupted switchover between different winding taps of an item of electrical equipment, such as a power transformer or a controllable reactor. For example, this makes it possible for the transmission ratio of the transformer or the inductance of the reactor to be changed. Double reversing change-over selectors are used to reverse the polarity of windings during power transformer operation. 
     All of these switches represent a highly safety-relevant component of the electrical equipment, because the switchover takes place while the equipment is in operation and is accordingly connected to a power network, for example. In extreme cases, malfunctions during operation can have serious technical and economic consequences. 
     SUMMARY 
     In an embodiment, the present disclosure provides a switch assembly that includes a switch; and a drive system for the switch. The drive system includes: a drive shaft connecting the drive system to the switch; a motor configured to drive the drive shaft; and a feedback system, which is configured to determine at least two values for a position of the drive shaft; and to generate a feedback signal on the basis of the at least two values; and a control device which is configured to influence an operation of the motor depending on the feedback signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Subject matter of the present disclosure will be described in even greater detail below based on the exemplary figures. All features described and/or illustrated herein can be used alone or combined in different combinations. The features and advantages of various embodiments will become apparent by reading the following detailed description with reference to the attached drawings, which illustrate the following: 
         FIG. 1  a schematic representation of an exemplary embodiment of a switch assembly according to the improved concept; and 
         FIG. 2  a schematic representation of a further exemplary embodiment of a switch assembly according to the improved concept. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention provide an improved concept for driving a switch, in particular an on-load tap-changer, diverter switch, selector, double reversing change-over selector, reversing change-over selector, change-over selector, circuit breaker, on-load switch or disconnecting switch, by means of which concept the operational reliability is increased. 
     The improved concept is based, inter alia, on the idea of equipping a drive shaft for driving the switch with a feedback system which is able to detect at least two values for a position of the drive shaft. The operation of the motor is influenced based on a feedback signal which is generated depending on the two values. 
     According to an embodiment of the improved concept, a switch assembly comprising a switch and a drive system for the switch is provided. The drive system has a drive shaft connecting the drive system to the switch, a motor for driving the drive shaft and a feedback system. The feedback system is designed to determine at least two values for a position of the drive shaft and to generate a feedback signal based on the at least two values. In addition, the drive system has a control device which is designed to influence an operation of the motor depending on the feedback signal. 
     According to at least one embodiment, the switch can be configured as an on-load tap-changer or a diverter switch or a selector or a double reversing change-over selector or a reversing change-over selector or a change-over selector or a circuit breaker or an on-load switch or a disconnecting switch. 
     The expression “values for the position of the drive shaft” also includes those values of measurement variables from which the position of the drive shaft can be unambiguously determined, if necessary within a tolerance range. 
     By determining at least two values for the position of the drive shaft, the control device can carry out a plausibility check of the position determination or a reconciliation of the two values and can thereby increase the reliability of the position determination and to reduce the corresponding residual risk of an incorrect position determination. In addition, a partial failure of the feedback device, such that only one value can still be determined for the position of the drive shaft, does not necessarily lead to the immediate stopping of the drive shaft. At least the switch can still be moved into a safe operating position in a controlled manner despite the partial failure. Ultimately, this increases the operational reliability of the drive system, the switch and the equipment. In summary, the determination of two values for the position of the drive shaft increases the reliability, by way of a partial failure being reliably detected, and availability, since switching is brought reliably to its conclusion despite the partial failure. 
     According to at least one embodiment, the drive system is used to drive a shaft of the switch, for example on-load tap-changer or a corresponding component of the on-load tap-changer. This causes the on-load tap-changer, for example, to perform one or more operations, such as a switchover between two winding taps of an item of equipment or parts of the switchover, such as a diverter switch operation, selector operation, change-over selector operation or double reversing change-over selector operation. 
     According to at least one embodiment, the drive shaft is connected directly or indirectly, in particular via one or more gear units, to the switch, in particular to the shaft of the switch. 
     According to at least one embodiment, the drive shaft is connected directly or indirectly, in particular via one or more gear units, to the diverter switch, selector, double reversing change-over selector, reversing change-over selector, circuit breaker, on-load switch or disconnecting switch, in particular to the shaft of the diverter switch, selector, double reversing change-over selector, reversing change-over selector, circuit breaker, on-load switch or disconnecting switch. 
     According to at least one embodiment, the drive shaft is connected directly or indirectly, in particular via one or more gears, to the motor, in particular to a motor shaft of the motor. 
     According to at least one embodiment, a position, in particular an absolute position, of the motor shaft corresponds to a position, in particular an absolute position, of the drive shaft. This means that the position of the drive shaft can be unambiguously deduced from the position of the motor shaft, if necessary within a tolerance range. 
     According to at least one embodiment, the influence includes open-loop control, closed-loop control, braking, acceleration, or stopping of the motor. For example, the closed-loop control may include position control, speed control, acceleration control, or torque control. At least in the case of such forms of control, it can be said that the drive system is a servo drive system. 
     According to at least one embodiment, the drive system comprises a monitoring unit which is designed to monitor the one or more operations of the switch, on-load tap-changer, diverter switch, selector, double reversing change-over selector, reversing change-over selector, change-over selector, circuit breaker, on-load switch or disconnecting switch using the feedback signal. The monitoring comprises in particular monitoring whether individual operations or parts thereof are carried out in an orderly fashion, in particular within predefined time windows. 
     According to at least one embodiment, the control device comprises a control unit and a power section for the open-loop- or closed-loop-controlled power supply of the motor. The control unit is designed for actuating the power section in response to at least one desired value, in particular position, speed or acceleration desired value. 
     According to at least one embodiment, the power section is designed as a converter or servo converter or as an equivalent electronic unit, in particular fully electronic unit, for drive machines. 
     According to various embodiments, the control device contains all or part of the feedback system. 
     According to at least one embodiment, the feedback system is designed to determine a first value of the at least two values for the position of the drive shaft according to a first method and to determine a second value of the at least two values for the position of the drive shaft according to a second method, wherein the two methods can differ from each other. This creates at least a redundancy or even a diverse redundancy that further increases operational reliability. 
     For example, the two methods may be based on the same or different technical or physical principles or may use the same or different components (hardware components). 
     According to at least one embodiment, one of the at least two values for the position of the drive shaft is a first value for an absolute position of the drive shaft. 
     According to at least one embodiment, another of the at least two values for the position of the drive shaft is a second value for an absolute position of the drive shaft. 
     The first value and the second value for the absolute position of the drive shaft can be compared by the control device for example. In the event of a significant deviation, the control device can output an error message or initiate a safety measure. 
     According to at least one embodiment, one of the at least two values for the position of the drive shaft is an incremental value for a position of the drive shaft or a value for a relative position of the drive shaft. 
     The first and/or the second value for the absolute position can then be compared by the control device with the incremental or relative value, whereby the plausibility of the first and/or second value for the absolute position can be checked. In the event of a significant deviation, the control device can output an error message and/or initiate a safety measure. 
     According to at least one embodiment, the feedback system is designed to determine a rotor position of the motor and to determine one of the at least two values for the position of the drive shaft depending on the rotor position. 
     According to at least one embodiment, the rotor position is an angular range in which a rotor of the motor is located, optionally combined with a number of complete rotations of the rotor. 
     Depending on the design of the rotor, in particular the number of pole pairs, the position or absolute position of the motor shaft can thus be determined accurately up to at least 180°, for example by the control device. By reduction by means of one or more gears, the accuracy of the position of the drive shaft that can be achieved as a result is significantly greater. In this case, the evaluation by the control device corresponds to a virtual encoder function, so to speak. Even in the event of a complete failure of an absolute encoder of the feedback system, at least one emergency mode can therefore be maintained and/or the switch, in particular on-load tap-changer, can be brought into a safe position. 
     According to at least one embodiment, the feedback system includes an absolute encoder that is designed and arranged to detect the absolute position of the drive shaft or an absolute position of another shaft that is connected to the drive shaft and to generate at least one output signal based on the detected position. The feedback system is designed to determine one of the at least two values for the position of the drive shaft, in particular the first and/or the second value for the absolute position, on the basis of the at least one output signal. 
     According to at least one embodiment, the absolute encoder is directly or indirectly attached to the motor shaft, the drive shaft, or a shaft coupled thereto. 
     According to at least one embodiment, the absolute encoder has a first output for outputting the first or second value for the absolute position and a second output for outputting the incremental or relative value for the position. 
     The expression “absolute encoder” includes both devices that determine two values for the position in different ways, and devices that contain two separate encoders, at least one of which is an absolute encoder. 
     According to at least one embodiment, the absolute encoder comprises a multi-turn encoder. 
     According to at least one embodiment, the absolute encoder is configured to detect the position of the drive shaft or the position of the further shaft on the basis of a first sampling method. 
     According to at least one embodiment, the absolute encoder is designed to additionally detect the position of the drive shaft or the position of the further shaft on the basis of a second sampling method that is independent of the first sampling method. 
     According to at least one embodiment, the first or second sampling method includes an optical, a magnetic, a capacitive, a resistive, or an inductive sampling method. 
     According to at least one embodiment, the first sampling method differs from the second sampling method. 
     According to at least one embodiment, the absolute encoder is connected to the drive shaft, the motor shaft or the further shaft in an interlocked manner. 
     According to at least one embodiment, the absolute encoder is additionally connected to the drive shaft, the motor shaft or the further shaft in a frictionally engaged or integrally bonded manner, for example by means of an adhesive connection. 
     The interlocked and additional integrally bonded or frictionally engaged connection further increases the attachment of the absolute encoder and ultimately the operational reliability. 
     According to and embodiment of the improved concept, a method for driving an on-load tap-changer is also provided. The method comprises determining at least two values for an absolute position of a drive shaft for driving the on-load tap-changer, generating a feedback signal on the basis of the at least two values and controlling a motor for driving the on-load tap-changer depending on the feedback signal. 
     Further embodiments and implementations of the method are directly apparent from the various embodiments of the tap changer assembly. In particular, individual or multiple components and/or arrangements which are described in relation to the tap changer assembly can be correspondingly implemented for carrying out the method. 
     In the following, aspects of the invention are explained in detail on the basis of exemplary embodiments with reference to the drawings. Components which are identical or functionally identical or which have an identical effect may be provided with identical reference signs. Identical components or components having an identical function may in some cases be explained only in relation to the figure in which they first appear. The explanation is not necessarily repeated in the subsequent figures. 
       FIG. 1  shows a schematic representation of an exemplary embodiment of a switch assembly  1  according to the improved concept with a switch  17  and a drive system  3 , which is connected to the switch  17  via a drive shaft  16 . The switch  17  can be an on-load tap-changer, diverter switch, selector, double reversing change-over selector, reversing change-over selector, change-over selector, circuit breaker, on-load switch or disconnecting switch. The drive system  3  includes a motor  12 , which can drive the drive shaft  16  via a motor shaft  16  and optionally via a gear unit  15 . A control device  2  of the drive system  3  comprises a power section  11 , which contains for example a converter, for the open-loop- or closed-loop-controlled power supply of the motor  12 , and a control unit  10  for actuating the power section  11 , for example via a bus  18 . The drive system  3  has an encoder system  13 , which serves as a feedback system  4  or is part of the feedback system  4  and is connected to the power section  11 . Furthermore, the encoder system  13  is directly or indirectly coupled to the drive shaft  16 . 
     The encoder system  13  is designed to detect a first value for a position, in particular an angular position, for example an absolute angular position, of the drive shaft  16 . For this purpose, the encoder system  13  can comprise, for example, an absolute encoder, in particular a multi-turn absolute encoder, which is attached to the drive shaft  16 , the motor shaft  14  or another shaft of which the position is unambiguously linked to the absolute position of the drive shaft  16 . For example, the position of the drive shaft  16  can be unambiguously determined from the position of the motor shaft  14 , for example via a transmission ratio of the gear unit  15 . 
     The fastening of the absolute encoder is embodied, for example, as a combination of an interlocked connection with a frictionally engaged and/or integrally bonded connection. 
     The feedback system  4  is additionally adapted to detect a second value for the position of the drive shaft  16 . 
     For this purpose, the encoder system  13  may be designed to detect the second value, in particular using a method which is different from a method according to which the first value for the position of the drive shaft  16  is detected. 
     Alternatively or additionally, the control device  2  can be designed to determine the second value from a rotor position of the motor  12 , effectively thus having a virtual encoder for detecting the second value. For this purpose, for example, an inductive feedback may be utilized by the movement of the rotor in motor windings of the motor  12 . Since a strength of the feedback varies periodically, signal analysis, for example FFT analysis, can be used to approximate the rotor position in particular. Since one full revolution of the drive shaft  16  corresponds to a plurality of revolutions of the rotor, the position of the drive shaft  16  can be inferred therefrom with much higher accuracy. 
     The control device  2 , in particular the control unit  10  and/or the power section  11 , is designed to control the motor  12  in an open-loop or closed-loop fashion depending on a feedback signal generated by the feedback system on the basis of the first and second values. 
     The control device  2 , for example the control unit  10 , can, for example, reconcile the two values for the position of the drive shaft  16  and/or perform a plausibility check of the position determination. 
       FIG. 2  shows a schematic representation of a further exemplary embodiment of a switch assembly  1  according to the improved concept, which is based on the embodiment according to  FIG. 1 . 
     The switch device  1  here optionally has a control cabinet  21 , within which the control unit  10 , the power section  11  and an optional man-machine interface  19  are arranged. The man-machine interface  19  is connected to the control unit  10  and can serve for control, maintenance or configuration purposes, for example during or outside of operation. 
     The motor  12 , the motor shaft  14  the encoder system  13  and/or the gear unit  15  can be located inside or outside the control cabinet. 
     The switch assembly  1 , in particular the control unit  10 , is coupled to a safety device  20 , which comprises, for example, a circuit breaker, in order to disconnect the switch assembly  1  or an item of electrical equipment to which the switch assembly  1  is assigned from a power network, for example in the event of a fault or malfunction of the switch assembly  1 . 
     A switch assembly  1  according to the improved concept increases the operational safety of the drive system  3 , the switch  17  and the equipment. By means of the described double position determination and corresponding comparisons, the residual risk of an incorrect position determination is reduced. 
     While subject matter of the present disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. Any statement made herein characterizing the invention is also to be considered illustrative or exemplary and not restrictive as the invention is defined by the claims. It will be understood that changes and modifications may be made, by those of ordinary skill in the art, within the scope of the following claims, which may include any combination of features from different embodiments described above. 
     The terms used in the claims should be construed to have the broadest reasonable interpretation consistent with the foregoing description. For example, the use of the article “a” or “the” in introducing an element should not be interpreted as being exclusive of a plurality of elements. Likewise, the recitation of “or” should be interpreted as being inclusive, such that the recitation of “A or B” is not exclusive of “A and B,” unless it is clear from the context or the foregoing description that only one of A and B is intended. Further, the recitation of “at least one of A, B and C” should be interpreted as one or more of a group of elements consisting of A, B and C, and should not be interpreted as requiring at least one of each of the listed elements A, B and C, regardless of whether A, B and C are related as categories or otherwise. Moreover, the recitation of “A, B and/or C” or “at least one of A, B or C” should be interpreted as including any singular entity from the listed elements, e.g., A, any subset from the listed elements, e.g., A and B, or the entire list of elements A, B and C. 
     REFERENCE SIGNS 
     
         
           1  Switch assembly 
           2  Control device 
           3  Drive system 
           4  Feedback system 
           10  Control unit 
           11  Power section 
           12  Motor 
           13  Encoder system 
           14  Motor shaft 
           15  Gear unit 
           16  Drive shaft 
           17  Switch 
           18  Bus 
           19  Man-machine interface 
           20  Safety device 
           21  Control cabinet