Transition circuit of thyristor mechanical hybrid on-load tap-changer
By introducing a thyristor module into the oil-immersed mechanical on-load tap-off switch, the natural shutdown of zero crossing is solved, and the oil temperature rise and contact burning problems caused by arcing is solved, which improves electrical life and reduces maintenance costs.
Patent Information
- Application Number
- CN202411382847.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2025-02-11
AI Technical Summary
The existing oil-immersed mechanical on-load tap-off switches are prone to arcing during the switching process, resulting in increased oil temperature and burning of contacts, and high maintenance costs.
The thyristor mechanical hybrid tap-off switch transition circuit is adopted, and the thyristor module is naturally shut down during the switching process, avoiding ablation of mechanical contacts and contamination of insulation oil, and achieving arc-free switching.
It greatly improves the electrical life of the on-load tap-off switch, reduces maintenance costs, and achieves arc-free switching on the basis of increasing limited costs.
Smart Images
Figure CN119419078A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of on-load tap changers, and more particularly to a thyristor-mechanical hybrid on-load tap changer transition circuit. Background Art
[0002] At present, power transformers with voltage levels of 35kV and above mainly use oil-immersed mechanical and oil-immersed vacuum on-load tap-changers. The oil-immersed mechanical on-load tap-changer has a large contact opening distance, reliable arc extinguishing, mature mechanical design, and good reliability and safety. However, the mechanical contacts of this switch arc in the oil, extinguish the arc in the oil, and the contacts are seriously burned. The oil is carbonized and contaminated to a high degree, and the maintenance cost is high. The oil-immersed vacuum on-load tap-changer generates an arc in a vacuum tube and relies on vacuum arc extinguishing to solve the problems of oil carbonization and contamination. However, this switch cannot avoid the generation of arcs, and the empty tube contacts will burn. The safety depends on the vacuum degree. Once the vacuum degree decreases, it will cause an accident. With the development of power electronics technology, thyristors are added on the basis of oil-immersed mechanical on-load tap-changers, and the characteristics of the thyristor's zero-crossing natural shutdown are used to realize arc-free switching of the on-load tap-changer. The oil temperature rise and contact burning caused by arc energy can be avoided on the basis of increasing limited costs, which can effectively improve the electrical life of the on-load tap-changer. The invention provides a transition circuit of a thyristor-mechanical hybrid on-load tap changer to realize arc-free switching of the on-load tap changer. Summary of the invention
[0003] In order to solve the technical problem of using thyristors to achieve arc-free switching of oil-immersed mechanical on-load tap changers in the background technology, the present invention provides a thyristor-mechanical hybrid on-load tap changer transition circuit. During the switching process, the thyristor module is naturally turned off at zero crossing to achieve the inability to switch each transition branch, which can avoid mechanical contact ablation and insulating oil pollution. On the basis of increasing limited costs, arc-free switching is achieved, and the electrical life of the on-load tap changer is greatly improved.
[0004] In order to achieve the above-mentioned object of the invention, the present invention provides a thyristor mechanical hybrid on-load tap changer transition circuit, characterized in that each phase of the transition circuit comprises: a pair of anti-parallel thyristor modules VT and a corresponding trigger pole switch G; two first and second main on-off contacts A, D, and corresponding first and second main on-off auxiliary contacts A', D'; two first and second transition contacts B, C, and corresponding first and second transition auxiliary contacts B', C'; two current limiting resistors, namely, an n-side current limiting resistor R and an n+1-side current limiting resistor R,
[0005] The upper end of the transition circuit is connected between the first tap n and the second tap n+1 of the transformer, and the lower end is connected to the current output terminal O.
[0006] In the above-mentioned thyristor mechanical hybrid on-load tap changer transition circuit, the upper end of the main on-off contact A is connected to the first tap n, and the lower end is connected to the current output terminal O; the upper end of the n-side current limiting resistor R is connected to the first tap n, and the lower end is connected to the upper end of the first transition contact B, and the lower end of the first transition contact B is connected to the current output terminal O; the upper end of the first main on-off auxiliary contact A' is connected to the first tap n, and the lower end is connected to the upper end of the thyristor module VT, and the lower end of the thyristor module VT is connected to the current output terminal O; the upper end of the first transition auxiliary contact B' is connected to the lower end of the n-side resistor R, and the lower end is connected to the upper end of the thyristor module VT;
[0007] The upper end of the second main on-off contact D is connected to the second tap n+1, and the lower end is connected to the current output terminal O; the upper end of the n+1 side current limiting resistor R is connected to the second tap n+1, and the lower end is connected to the upper end of the second transition contact C, and the lower end of the second transition contact C is connected to the current output terminal O; the upper end of the second main on-off auxiliary contact D' is connected to the second tap n+1, and the lower end is connected to the upper end of the thyristor module VT; the upper end of the second transition auxiliary contact C' is connected to the lower end of the n+1 side resistor R, and the lower end is connected to the upper end of the thyristor module VT.
[0008] In the above-mentioned thyristor mechanical hybrid on-load tap changer transition circuit, the thyristor module VT is provided with two thyristors SCR, two trigger pole switches G, an overvoltage protection device varistor U, two diodes D1 (silicon stacks), two resistors r,
[0009] The two thyristors SCR are connected in anti-parallel to form an upper end and a lower end respectively. The varistor U is connected in parallel to the upper and lower ends to protect the thyristor module from overvoltage damage. The gates of the two thyristors SCR are connected to one end of the trigger switch G through a reverse-connected diode D1 in series with a resistor r. The other end of the trigger switch G is connected to the anode end of the corresponding thyristor. The diode D1 prevents the gate from reverse current, and the resistor r is used to limit the gate current.
[0010] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0011] ① The first main on-off contact A on the first tap n side is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the first tap n side is closed; ④ The second transition auxiliary contact B' is disconnected; ⑤ The second transition contact C on the second tap n+1 side is disconnected; ⑥ The second transition auxiliary contact C' is closed; ⑦ The second main on-off contact D on the second tap n+1 side is disconnected; ⑧ The second main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed, and the thyristor module VT is triggered and turned on after the trigger pole switch G is closed.
[0012] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0013] ① The first main on-off contact A on the n side of the first tap tap is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the n side of the first tap tap is closed; ④ The first transition auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 side of the second tap tap is closed; ⑥ The second transition auxiliary contact C' is closed; ⑦ The first main on-off contact D on the n+1 side of the second tap tap is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed, and the thyristor module VT is short-circuited by the transition contact C on the n+1 side.
[0014] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0015] ① The first main on-off contact A on the first tap n side is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the first tap n side is closed; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is opened; ⑦ The first main on-off contact D on the second tap n+1 side is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0016] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0017] ① The first main on-off contact A on the first tap n side is open; ② The first main on-off auxiliary contact A' is open; ③ The first transition contact B on the first tap n side is open; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is open; ⑦ The first main on-off contact D on the second tap n+1 side is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed,
[0018] When the first transition contact B is opened, a break voltage is generated on the break of the first transition contact B. The break voltage is applied to the thyristor module VT to trigger the thyristor to turn on. The original contact current of the first transition contact B flows to the current output terminal O through VT.
[0019] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0020] ① The first main on-off contact A on the first tap n side is open; ② The first main on-off auxiliary contact A' is open; ③ The first transition contact B on the first tap n side is open; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is open; ⑦ The second main on-off contact D on the second tap n+1 side is disconnected; ⑧ The second main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is opened,
[0021] After the trigger pole switch G is turned on, the trigger end of the thyristor module fails, and the thyristor module VT current passes through zero and is naturally turned off.
[0022] The present invention also provides a switching method for a thyristor-mechanical hybrid on-load tap changer transition circuit, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows:
[0023] ① The first main on-off contact A on the n side of the first tap is opened; ② The first main on-off auxiliary contact A' is opened; ③ The second transition contact B on the n tap side is opened; ④ The second transition auxiliary contact B' is opened; ⑤ The second transition contact C on the n+1 side of the second tap is closed; ⑥ The second transition auxiliary contact C' is opened; ⑦ The second main on-off contact D on the n+1 side of the second tap is disconnected; ⑧ The second main on-off auxiliary contact D' is closed; ⑨ The trigger switch G is opened.
[0024] In the above-mentioned thyristor mechanical hybrid on-load tap changer transition circuit, the triggering process of the thyristor module VT is as follows: the first main on-off contact A is set as a break, at which time the AC current flows from the first tap n to the current output terminal O, and the moment the first main on-off contact A is opened, a break voltage is generated at the break of the contact A, and the break voltage forms a forward bias voltage for the thyristor SCR on the upper side of the thyristor module VT, and at the same time, the break voltage forms a trigger current through the corresponding closed trigger pole switch G, resistor r and diode on the upper side of the thyristor module VT, and the thyristor SCR on the upper side of the thyristor module VT is turned on, and the first branch of the original current The tap n—first main on-off contact A—current output terminal O is converted to the first tap n—first main on-off auxiliary contact A'—thyristor SCR on the upper side of the thyristor module VT—current output terminal O; the shutdown process of the thyristor module VT is: the first main on-off contact A is set as a break, the first main on-off contact A has been fully opened, and the current triggers the SCR to turn on under the action of the break voltage to form a current path. The break triggers the switch G. After the SCR current of the thyristor module VT passes through zero, the trigger pole switch G cannot continue to trigger the thyristor, and the thyristor is turned off, disconnecting the current from the first tap n to the current output terminal O.
[0025] The thyristor-mechanical hybrid on-load tap changer transition circuit of the present invention adds a pair of anti-parallel thyristor modules per phase on the basis of the existing oil-immersed mechanical on-load tap changer transition circuit. During the switching process, the thyristor modules are naturally turned off at zero crossing to achieve the inability to switch each transition branch, thereby avoiding mechanical contact ablation and insulating oil pollution. Arc-free switching is achieved on the basis of increasing limited costs, thereby greatly improving the electrical life of the on-load tap changer. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:
[0027] Figure 1 It is a simplified schematic diagram of a thyristor mechanical hybrid on-load tap changer transition circuit according to a specific embodiment of the present invention;
[0028] Figure 2 It is a circuit diagram of a thyristor module of a thyristor-mechanical hybrid on-load tap changer transition circuit according to a specific embodiment of the present invention;
[0029] Figure 3a-3o It is a switching program diagram of a transition circuit of a thyristor-mechanical hybrid on-load tap changer according to a specific embodiment of the present invention;
[0030] Figure 4 It is a trigger principle diagram of a thyristor module according to a specific implementation mode of the present invention. DETAILED DESCRIPTION
[0031] The present invention will be further described below in conjunction with the accompanying drawings.
[0032] Figure 1 1 is a simplified schematic diagram of a thyristor mechanical hybrid on-load tap changer transition circuit according to a specific embodiment of the present invention. Figure 1 As shown, each phase of the thyristor mechanical hybrid on-load tap changer transition circuit of the present invention includes:
[0033] A pair of anti-parallel thyristor modules VT and a corresponding trigger pole switch G; including two main on-off contacts A, D and corresponding auxiliary contacts A', D'; including two transition contacts B, C and corresponding auxiliary contacts B', C'; including two current limiting resistors, an n-side current limiting resistor R and an n+1-side current limiting resistor R.
[0034] The upper end of the main on-off contact A is connected to the tap n, and the lower end is connected to the current output terminal O. The upper end of the n-side current limiting resistor R is connected to the tap n, and the lower end is connected to the upper end of the mechanical transition contact B, and the lower end of the mechanical transition contact B is connected to the current output terminal O. The upper end of the auxiliary contact A' is connected to the tap n, and the lower end is connected to the upper end of the thyristor module VT, and the lower end of the thyristor module VT is connected to the current output terminal O. The upper end of the auxiliary contact B' is connected to the lower end of the n-side resistor, and the lower end is connected to the upper end of the thyristor module VT.
[0035] The upper end of the main on-off contact D is connected to the tap n+1, and the lower end is connected to the current output terminal O. The upper end of the current limiting resistor R on the n+1 side is connected to the tap n+1, and the lower end is connected to the upper end of the mechanical transition contact C, and the lower end of the mechanical transition contact C is connected to the current output terminal O. The upper end of the auxiliary contact D' is connected to the tap n+1, and the lower end is connected to the upper end of the thyristor module VT. The upper end of the auxiliary contact C' is connected to the lower end of the resistor on the n+1 side, and the lower end is connected to the upper end of the thyristor module VT.
[0036] Figure 2 It is a thyristor module circuit diagram of a thyristor mechanical hybrid on-load tap changer transition circuit according to a specific embodiment of the present invention. The thyristor module VT is provided with two thyristors SCR, two trigger pole switches G, an overvoltage protection device varistor U, two diodes D1 (silicon stacks), and two resistors r. The two thyristors SCR are connected in anti-parallel to form an upper end and a lower end respectively. The varistor U is connected in parallel with the upper and lower ends to protect the thyristor module from overvoltage damage. The gates of the two thyristors SCR are connected to one end of the trigger switch G through a reverse-connected diode D1 (silicon stack) in series with a resistor r, and the other end of the trigger switch G is connected to the anode end of the corresponding thyristor. The diode D1 prevents the gate from reverse current, and the resistor r is used to limit the gate current.
[0037] FIG3 is a switching procedure diagram of a transition circuit of a thyristor-mechanical hybrid on-load tap changer according to a specific embodiment of the present invention. The procedure of switching from the transformer n-tap tap to the n+1 tap tap by using the thyristor-mechanical hybrid on-load tap changer is as follows:
[0038] (1) Figure 3a ① The main on-off contact A on the n tap side is closed; ② The auxiliary contact A' is closed; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is disconnected; ⑥ The auxiliary contact C' is disconnected; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0039] Current: n tap side tap - main on-off contact A - current output terminal O.
[0040] (2) Figure 3b ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is closed; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is disconnected; ⑥ The auxiliary contact C' is disconnected; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0041] At the moment A is opened, a break voltage is generated on the A break. The break voltage is applied to the thyristor module VT to trigger the thyristor to turn on, and the original A contact current flows to the current output terminal O through VT.
[0042] Current: n tap side tap - thyristor module VT - current output terminal O.
[0043] (3) Figure 3c ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is closed; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is disconnected; ⑥ The auxiliary contact C' is disconnected; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is opened.
[0044] The thyristor module VT is naturally turned off when the current passes through zero.
[0045] Current: n-tap side tap—n-side resistor R—transition contact B—current output terminal O.
[0046] (4) Figure 3d , 3e ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is disconnected; ⑥ The auxiliary contact C' is closed; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is opened.
[0047] Current: n-tap side tap—n-side resistor R—transition contact B—current output terminal O.
[0048] (5) Figure 3f ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is disconnected; ⑥ The auxiliary contact C' is closed; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0049] After G is turned off, the thyristor module VT is triggered to turn on.
[0050] Current: n-tap side tap—n-side resistor R—transition contact B—current output terminal O.
[0051] n+1 tap side tap—n+1 side resistor R—thyristor module VT—current output terminal O.
[0052] A bridge is formed between the n tap and the n+1 tap.
[0053] (6) Figure 3g ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is closed; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0054] The thyristor module VT is short-circuited by the transition contact C on the n+1 side.
[0055] Current: n-tap side tap—n-side resistor R—transition contact B—current output terminal O.
[0056] n+1 tap side tap—n+1 side resistor R—transition contact C—current output terminal O.
[0057] The bridging between the n-tap and the n+1-tap continues.
[0058] (7) Figure 3h , Figure 3i ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is closed; ④ The auxiliary contact B' is closed; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0059] Current: n-tap side tap—n-side resistor R—transition contact B—current output terminal O.
[0060] n+1 tap side tap—n+1 side resistor R—transition contact C—current output terminal O.
[0061] The bridging between the n-tap and the n+1-tap continues.
[0062] (8) Figure 3j ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is opened; ④ The auxiliary contact B' is closed; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
[0063] At the moment B is opened, a break voltage is generated on the B break. The break voltage is applied to the thyristor module VT to trigger the thyristor to turn on, and the original B contact current flows to the current output terminal O through VT.
[0064] Current: n-tap side tap—n-side resistor R—thyristor module VT—current output terminal O.
[0065] n+1 tap side tap—n+1 side resistor R—transition contact C—current output terminal O.
[0066] The bridging between the n-tap and the n+1-tap continues.
[0067] (9) Figure 3k ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is opened; ④ The auxiliary contact B' is closed; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is disconnected; ⑨ The trigger switch G is opened.
[0068] After G is turned on, the trigger end of the thyristor module fails, and the thyristor module VT current passes through zero and is naturally turned off.
[0069] Current: n+1 tap side tap—n+1 side resistor R—transition contact C—current output terminal O.
[0070] Disconnect the bridge.
[0071] (10) Figure 3l , Figure 3m ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is opened; ④ The auxiliary contact B' is opened; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is closed; ⑨ The trigger switch G is opened.
[0072] Current: n+1 tap side tap—n+1 side resistor R—transition contact C—current output terminal O.
[0073] (11) Figure 3n ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is opened; ④ The auxiliary contact B' is opened; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is disconnected; ⑧ The auxiliary contact D' is closed; ⑨ The trigger switch G is closed.
[0074] After G is turned off, the thyristor module VT is triggered to turn on.
[0075] Current: n+1 tap side tap—auxiliary contact D'—current output terminal O.
[0076] (12) Figure 3o ① The main on-off contact A on the n tap side is opened; ② The auxiliary contact A' is opened; ③ The transition contact B on the n tap side is opened; ④ The auxiliary contact B' is opened; ⑤ The transition contact C on the n+1 tap side is closed; ⑥ The auxiliary contact C' is opened; ⑦ The main on-off contact D on the n+1 tap side is closed; ⑧ The auxiliary contact D' is closed; ⑨ The trigger switch G is closed.
[0077] The VT path of the thyristor module is short-circuited by the main on-off contact D.
[0078] Current: n+1 tap side tap—main on-off contact D—current output terminal O.
[0079] Through the above process, a single thyristor dual resistor circuit realizes the conversion of the transformer tap n to n+1. If the transformer tap n+1 is converted to n, the reverse process can be realized.
[0080] Figure 4 It is a triggering and shutting down principle diagram of the thyristor module according to a specific embodiment of the present invention.
[0081] The triggering process of the thyristor module is explained by taking the A break as an example. At this time, the AC current flows from the tap n to the current output terminal O. The moment the main on-off contact A opens, the A contact break generates a break voltage. The break voltage forms a forward bias voltage for the thyristor SCR on the upper side of VT. At the same time, the break voltage forms a trigger current through the corresponding closed G, resistor r and diode on the upper side of VT. Therefore, the thyristor SCR on the upper side of VT is turned on, and the original current tap n—main on-off contact A—current output terminal O is converted to tap n—auxiliary contact A'—thyristor SCR on the upper side of VT—current output terminal O.
[0082] The shutdown process of the thyristor module is explained using the A break as an example. The main on-off contact A has been fully opened. The current triggers the SCR to turn on under the action of the break voltage to form a current path. The break triggers switch G. After the SCR current of the thyristor module passes through zero, the trigger G cannot continue to trigger the thyristor, so the thyristor is turned off, thereby disconnecting the current from the tap n to the current output terminal O.
[0083] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.
Claims
1. A thyristor mechanical hybrid on-load tap changer transition circuit, characterized in that: Each phase of the transition circuit includes: a pair of anti-parallel thyristor modules VT and a corresponding trigger pole switch G; two first and second main on-off contacts A, D, and corresponding first and second main on-off auxiliary contacts A', D'; two first and second transition contacts B, C, and corresponding first and second transition auxiliary contacts B', C'; two current limiting resistors, namely, n-side current limiting resistor R and n+1-side current limiting resistor R, The upper end of the transition circuit is connected between the first tap n and the second tap n+1 of the transformer, and the lower end is connected to the current output terminal O.
2. A thyristor mechanical hybrid on-load tap changer transition circuit according to claim 1, characterized in that: The upper end of the main on-off contact A is connected to the first tap n, and the lower end is connected to the current output terminal O; the upper end of the n-side current limiting resistor R is connected to the first tap n, and the lower end is connected to the upper end of the first transition contact B, and the lower end of the first transition contact B is connected to the current output terminal O; the upper end of the first main on-off auxiliary contact A' is connected to the first tap n, and the lower end is connected to the upper end of the thyristor module VT, and the lower end of the thyristor module VT is connected to the current output terminal O; the upper end of the first transition auxiliary contact B' is connected to the lower end of the n-side resistor R, and the lower end is connected to the upper end of the thyristor module VT; The upper end of the second main on-off contact D is connected to the second tap n+1, and the lower end is connected to the current output terminal O; the upper end of the n+1 side current limiting resistor R is connected to the second tap n+1, and the lower end is connected to the upper end of the second transition contact C, and the lower end of the second transition contact C is connected to the current output terminal O; the upper end of the second main on-off auxiliary contact D' is connected to the second tap n+1, and the lower end is connected to the upper end of the thyristor module VT; the upper end of the second transition auxiliary contact C' is connected to the lower end of the n+1 side resistor R, and the lower end is connected to the upper end of the thyristor module VT.
3. A thyristor mechanical hybrid on-load tap changer transition circuit according to claim 1 or 2, characterized in that: The thyristor module VT is provided with two thyristors SCR, two trigger pole switches G, an overvoltage protection device varistor U, two diodes D1 (silicon stacks), two resistors r, The two thyristors SCR are connected in anti-parallel to form an upper end and a lower end respectively. The varistor U is connected in parallel to the upper and lower ends to protect the thyristor module from overvoltage damage. The gates of the two thyristors SCR are connected to one end of the trigger switch G through a reverse-connected diode D1 in series with a resistor r. The other end of the trigger switch G is connected to the anode end of the corresponding thyristor. The diode D1 prevents the gate from reverse current, and the resistor r is used to limit the gate current.
4. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from the first tap n of the transformer to the second tap n+1 is as follows: ① The first main on-off contact A on the first tap n side is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the first tap n side is closed; ④ The second transition auxiliary contact B' is disconnected; ⑤ The second transition contact C on the second tap n+1 side is disconnected; ⑥ The second transition auxiliary contact C' is closed; ⑦ The second main on-off contact D on the second tap n+1 side is disconnected; ⑧ The second main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed, and the thyristor module VT is triggered and turned on after the trigger pole switch G is closed.
5. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows: ① The first main on-off contact A on the n side of the first tap tap is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the n side of the first tap tap is closed; ④ The first transition auxiliary contact B' is disconnected; ⑤ The transition contact C on the n+1 side of the second tap tap is closed; ⑥ The second transition auxiliary contact C' is closed; ⑦ The first main on-off contact D on the n+1 side of the second tap tap is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed, and the thyristor module VT is short-circuited by the transition contact C on the n+1 side.
6. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from the first tap n of the transformer to the second tap n+1 is as follows: ① The first main on-off contact A on the first tap n side is opened; ② The first main on-off auxiliary contact A' is opened; ③ The first transition contact B on the first tap n side is closed; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is opened; ⑦ The first main on-off contact D on the second tap n+1 side is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed.
7. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows: ① The first main on-off contact A on the first tap n side is open; ② The first main on-off auxiliary contact A' is open; ③ The first transition contact B on the first tap n side is open; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is open; ⑦ The first main on-off contact D on the second tap n+1 side is disconnected; ⑧ The first main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is closed, When the first transition contact B is opened, a break voltage is generated on the break of the first transition contact B. The break voltage is applied to the thyristor module VT to trigger the thyristor to turn on. The original contact current of the first transition contact B flows to the current output terminal O through VT.
8. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from a first tap n of a transformer to a second tap n+1 is as follows: ① The first main on-off contact A on the first tap n side is open; ② The first main on-off auxiliary contact A' is open; ③ The first transition contact B on the first tap n side is open; ④ The first transition auxiliary contact B' is closed; ⑤ The second transition contact C on the second tap n+1 side is closed; ⑥ The second transition auxiliary contact C' is open; ⑦ The second main on-off contact D on the second tap n+1 side is disconnected; ⑧ The second main on-off auxiliary contact D' is disconnected; ⑨ The trigger switch G is opened, After the trigger pole switch G is turned on, the trigger end of the thyristor module fails, and the thyristor module VT current passes through zero and is naturally turned off.
9. A method for switching a transition circuit of a thyristor-mechanical hybrid on-load tap changer as claimed in claim 1 or 2, wherein the procedure for switching the thyristor-mechanical hybrid on-load tap changer from the first tap n of the transformer to the second tap n+1 is as follows: ① The first main on-off contact A on the n side of the first tap is opened; ② The first main on-off auxiliary contact A' is opened; ③ The second transition contact B on the n tap side is opened; ④ The second transition auxiliary contact B' is opened; ⑤ The second transition contact C on the n+1 side of the second tap is closed; ⑥ The second transition auxiliary contact C' is opened; ⑦ The second main on-off contact D on the n+1 side of the second tap is disconnected; ⑧ The second main on-off auxiliary contact D' is closed; ⑨ The trigger switch G is opened.
10. The thyristor mechanical hybrid on-load tap changer transition circuit according to claim 3, characterized in that: The triggering process of the thyristor module VT is as follows: the first main on-off contact A is set as a break, at which time the AC current flows from the first tap n to the current output terminal O. At the moment when the first main on-off contact A is opened, a break voltage is generated at the A contact break, and the break voltage forms a forward bias voltage for the thyristor SCR on the upper side of the thyristor module VT. At the same time, the break voltage forms a trigger current through the corresponding closed trigger pole switch G, resistor r and diode on the upper side of the thyristor module VT. The thyristor SCR on the upper side of the thyristor module VT is turned on, and the original current is converted from the first tap n—the first main on-off contact A—the current output terminal O to the first tap n—the first main on-off auxiliary contact A'—the thyristor SCR on the upper side of the thyristor module VT—the current output terminal O; The shutdown process of the thyristor module VT is as follows: the first main on-off contact A is set as a break, the first main on-off contact A is fully opened, and the current triggers the SCR to conduct under the action of the break voltage to form a current path. The break triggers the switch G. After the SCR current of the thyristor module VT passes through zero, the trigger pole switch G cannot continue to trigger the thyristor, and the thyristor is turned off, disconnecting the current from the first tap n to the current output terminal O.