Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F29/00—Variable transformers or inductances not covered by group H01F21/00
  • H01F29/02—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
  • H01F29/04—Variable transformers or inductances not covered by group H01F21/00 with tappings on coil or winding; with provision for rearrangement or interconnection of windings having provision for tap-changing without interrupting the load current
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/0005—Tap change devices
  • H01H9/0016—Contact arrangements for tap changers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/0005—Tap change devices

Definitions

• the invention relates to an on-load tap changer for uninterrupted switching between winding taps of a tapped transformer under load.
• the on-load tap changer consists of a mechanical tap selector for power-free preselection of the respective winding tap to which switching is to take place, and a diverter switch with semiconductor switching elements as switching means for the actual uninterrupted switching from the previous winding tap to the previously selected new winding tap under load.
• On-load tap changers of this type are usually also referred to as hybrid tap changers because they also have mechanical contacts in addition to the electronic power switching means.
• Such a hybrid tap changer is known from EP 2319058 B1.
• This has two load branches, each of which connects a winding tap via a mechanical switch and a series connection of two oppositely connected IGBTs with a common load shunt.
• a diode is provided in parallel with each IGBT.
• a varistor is in turn provided in parallel with each individual IGBT.
• each of the load branches is bridged with a permanent mechanical main contact.
• the IGBTs on both sides are controlled by a common IGBT driver.
• the mechanical tap selector and possibly other mechanical switching elements provided in the diverter switch are actuated by means of a motor drive, whereas the electronic power switching means are operated via a separate actuating means, which must be supplied with power.
• the improved concept is based on the idea of supplementing the fixed contacts of the on-load tap changer, which can each be connected to a winding tap of the control winding of the transformer, with an additional connection contact, which is an auxiliary contact of the on-load tap-changer can be contacted.
• an on-load tap changer for uninterrupted switching between winding taps of a tapped transformer.
• the on-load tap changer includes a first fixed contact, which can be connected to a first winding tap of the tapped transformer, and a second fixed contact, which can be connected to a second winding tap of the tapped transformer.
• the total number of fixed contacts depends on the number of winding taps.
• a first selector arm of the on-load tap changer can contact each of the fixed contacts and a second selector arm can also contact each of the fixed contacts.
• the on-load tap changer has a diverter switch.
• the on-load tap changer includes an additional connection contact, which is arranged analogously to the fixed contacts, and an auxiliary contact, which can optionally contact the connection contact or one of the fixed contacts.
• connection contact is designed in such a way that it can be contacted by the auxiliary contact.
• Each fixed contact is designed in such a way that it can be contacted by the first and/or the second selector arm.
• Each fixed contact preferably has a first contact area which can be contacted by the first selector arm and a second contact area which can be contacted by the second selector arm.
• the first or the second contact area can be contacted by the auxiliary contact.
• connection contact is bridged to the second fixed contact.
• connection contact does not have to be electrically connected to an additional winding tap.
• the auxiliary contact is designed to be mechanically coupled to the first selector arm.
• the diverter switch for switching has a plurality of semiconductor switching elements which are controlled by a control unit are operable.
• the semiconductor switching elements are preferably in the form of IGBT switching elements and/or thyristors and/or JFET switching elements and/or MOSFET switching elements and/or integrated gate commutated thyristors (IGCT).
• the semiconductor switching elements are particularly preferably in the form of an IGBT with diodes in a bridge circuit.
• control unit is designed as a microcontroller.
• control unit and thus also the semiconductor switching elements are supplied with power while the auxiliary contact makes contact with the connection contact or one of the fixed contacts and the first selector arm also makes contact with one of the fixed contacts.
• the first selector arm and the auxiliary contact Due to the mechanical coupling of the first selector arm and the auxiliary contact, the first selector arm and the auxiliary contact cannot be on the same fixed contact or on the connection contact at the same time during the switching process. This in turn means that at any time during the switching process in which the first selector arm contacts a fixed contact, a voltage of a step voltage is present between the first selector arm and the auxiliary contact, through which the control unit is supplied with power.
• the control unit and thus also the semiconductor switching elements are operated independently by means of the applied step voltage.
• An additional energy supply from the outside, for example through a motor controller, is therefore not required.
• control unit has an energy store which is charged when the control unit is supplied with power.
• the energy store is charged via the voltage difference that exists between the first selector arm and the auxiliary contact due to the mechanical coupling and the contacting of different fixed contacts or the connection contact and the first fixed contact.
• the energy store is preferably formed from ceramic capacitors and accordingly has a high temperature resistance.
• a switched-mode power supply with an extremely wide input voltage range is preferably used to charge the energy store, and it still works even at low step voltages.
• a method for actuating an on-load tap changer that is designed according to the first aspect of the improved concept is specified.
• the method includes the following steps for switching from a first fixed contact to a second fixed contact:
• switching over from the second fixed contact to a third fixed contact which is designed according to the second fixed contact and is connected to a third winding tap of the stepped transformer, comprises the following steps:
• FIG. 1 shows a schematic representation of an exemplary embodiment of an on-load tap changer according to the improved concept
• Figure 2a to 2g an exemplary switching sequence of the on-load tap changer from Figure 1.
• FIG. 1 shows a schematic representation of an exemplary embodiment of an on-load tap changer 10 for a tapped transformer 1 based on the improved concept.
• the tapped transformer 1 has a main winding 2 and a control winding 3 with different winding taps Nj, Nj+i, ..., NN, which are switched on and off by the on-load tap changer 10.
• the on-load tap changer 10 comprises at least a first fixed contact 12, which can be connected to a first winding tap Nj, a second fixed contact 13, which can be connected to a second winding tap Nj+i, and a third fixed contact 14, which can be connected to a third winding tap NJ+2 of the control winding 3 of the tapped transformer 1 can be connected.
• the total number of fixed contacts depends on the number of winding taps.
• the on-load tap changer 10 has another connection contact 11 that is connected to the second fixed contact 13 is bridged. The connection contact 11 is not directly connected to any of the winding taps Nj, Nj+i, NN.
• the on-load tap changer 10 For power-free preselection of the fixed contacts 12, 13, the on-load tap changer 10 includes a selector 30 with a first selector arm 31 and a second selector arm 32, which can be operated independently and can contact each of the fixed contacts. In addition to the selector arms 31, 32, the on-load tap changer 10 has an auxiliary contact 33 which is mechanically coupled to the first selector arm 31.
• the on-load tap changer 10 also includes a diverter switch 20 for performing the actual diverter switch between the preselected fixed contacts 12, 13.
• the diverter switch 20 has a total of three current branches.
• a varistor 28 is arranged in parallel with the first and the second auxiliary branch 26, 27 in each case.
• the semiconductor switching elements 22 and 23 are actuated by a control unit 21 .
• the described, specific circuit arrangement of the diverter switch 20 was selected as an example.
• the improved concept can be implemented in any on-load tap changer that has a diverter switch with semiconductor switching elements as switching means for uninterrupted switching.
• the on-load tap changer 10 is in a stationary position.
• the first and the second selector arm 31, 32 are both located on the first fixed contact 12.
• the auxiliary contact 33 is on the additional connection contact 11, which is bridged to the second fixed contact 13.
• the load current I L flows from the contacted fixed contact 12 via the first selector arm 31, the main branch 24 and the closed mechanical switching element 25 to the load dissipation 15.
• the two semiconductor switching elements 22 and 23 are switched off.
• FIGS. 2a to 2g An exemplary switching sequence of the on-load tap changer from FIG. 1 is shown in FIGS. 2a to 2g.
• the first semiconductor switching element 22 is switched on by means of the control unit 21 in a first step (FIG. 2a).
• the second selector arm 32 which is de-energized, is moved from the first fixed contact 12 to the second fixed contact 13.
• the mechanical switching element 25 is then opened (cf. FIG. 2c).
• the load current II now flows via the first auxiliary branch 26 and the activated first semiconductor switching element 22.
• the first semiconductor switching element 22 is preferably switched off when the current passes through zero.
• the course of the current over time can, for example, be detected by the control unit 21 by means of a current sensor (not shown), which is arranged in the current branch of the lead 15 .
• a current sensor not shown
• the load current II is transferred to the varistor 28 arranged parallel thereto.
• the second semiconductor switching element 23 is switched on after a specified period, for example 5 ps.
• the load current II is thus switched to the second fixed contact 13 and flows from the second selector arm 32 via the second auxiliary branch 27 and the activated second semiconductor switching element 23 to the load dissipation 15.
• the first selector arm 31, which is now de-energized, is then switched over to the second fixed contact 13 and, at the same time, the auxiliary contact 33 is switched over from the connection contact 11 to the first fixed contact 12 (FIG. 2f).
• the mechanical switching element 25 is closed again and then the second semiconductor switching element 23 is switched off by the control unit 21.
• the on-load tap changer 10 has now reached the second stationary position.
• the load current I L goes back to the main branch 24 .
• the first and the second selector arm 31, 32 are both located on the second fixed contact 13 and the auxiliary contact 33 on the first fixed contact 12.
• the load current II now flows from the second fixed contact 13 via the first selector arm 31 and the main branch 24 with the closed mechanical Switching element 25 for load dissipation 15. The load switching to the second fixed contact 13 is thus completed.
• a changeover from the second fixed contact 13 to the third fixed contact 14 takes place analogous to steps 2a-2g, with the only difference that the auxiliary contact 33 is not on the connection contact 11 at the beginning of the switchover, but on a fixed contact, namely the first fixed contact 12.
• Switching in the opposite direction for example from the second fixed contact 13 to the first fixed contact 12, takes place exactly in the reverse order, that is, according to FIGS. 2g to 2a.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Housings And Mounting Of Transformers (AREA)
• Keying Circuit Devices (AREA)
• Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=78078234

Family Applications (1)

Country Status (5)

Family Cites Families (6)

• 2020
  • 2020-10-29 DE DE102020128463.2A patent/DE102020128463A1/de active Pending
• 2021
  • 2021-09-30 EP EP21786426.3A patent/EP4226403A1/de active Pending
  • 2021-09-30 CN CN202180071389.7A patent/CN116438616A/zh active Pending
  • 2021-09-30 WO PCT/EP2021/076970 patent/WO2022089870A1/de unknown
  • 2021-09-30 US US18/250,752 patent/US20230411072A1/en active Pending

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