A switching circuit and a control method for a vacuum on-load tap changer
By using a switching circuit designed with symmetrical timing and a single transition resistor, the problem of asymmetrical switching timing in vacuum on-load tap changers is solved, simplifying mechanical design, reducing switching costs, improving arc extinguishing effect, and protecting transformer insulation performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA ELECTRIC POWER RESEARCH INSTITUTE CO LTD
- Filing Date
- 2022-11-10
- Publication Date
- 2026-07-03
AI Technical Summary
Existing vacuum on-load tap changers have asymmetrical switching timing, resulting in complex structures that require two sets of mechanical drive components. Furthermore, their arc extinguishing effect is poor, which affects the insulation performance of the transformer.
A switching circuit design consisting of a main current-carrying switch M1, a main current-carrying switch M2, a changeover switch T, a vacuum circuit breaker V1, a vacuum circuit breaker V2, a vacuum circuit breaker V3, and a transition resistor R is adopted to achieve symmetrical timing switching, and the current switching task is shared by the three vacuum circuit breakers.
It simplifies the mechanical design, saves on switch manufacturing costs, and improves the arc extinguishing effect and protects the transformer insulation performance through symmetrical timing and single transition resistor design.
Smart Images
Figure CN116266498B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of tap changer technology, and more specifically, to a switching circuit and control method for a vacuum on-load tap changer. Background Technology
[0002] When an on-load tap changer performs on-load voltage regulation, an electric arc is generated between the moving and stationary contacts. This arc erodes the contacts and decomposes the transformer oil, significantly reducing its insulation performance. As a type of on-load tap changer, the vacuum on-load tap changer primarily relies on the vacuum tube of the switching switch to extinguish the arc, ensuring that the arc and hot gases are not exposed. The oil in the tap changer's oil chamber does not carbonize or become contaminated, requiring no oil purification, and the burning and corrosion of the contacts in the vacuum tube are minimized.
[0003] In the past, the timing of the switching core of the on-load tap changer was asymmetrical when switching from odd tap to even tap and from even tap to odd tap. This resulted in two sets of mechanical drive components (cams or grooved wheels) being required for each switching. During repeated switching, a "track-changing" operation was required, which led to a complex switch structure. Summary of the Invention
[0004] To address the above problems, this invention proposes a switching circuit for a vacuum on-load tap changer, comprising: a main current-carrying switch M1, a main current-carrying switch M2, a changeover switch T, a vacuum circuit breaker V1, a vacuum circuit breaker V2, a vacuum circuit breaker V3, and a transition resistor R.
[0005] The main switch M1 connects the N-tap side of the switching circuit to the neutral point of the transformer;
[0006] The main switch M2 connects the N+1 tap side of the switching circuit to the neutral point of the transformer;
[0007] The fixed end of the changeover switch T is connected to the neutral point of the transformer, and the actuating arm of the changeover switch T switches between the main switch M1 and the main switch M2.
[0008] The vacuum circuit breaker V1 connects the fixed terminal T1 of the transfer switch T and one end of the vacuum circuit breaker V3, and is connected in parallel with the transition resistor R.
[0009] The vacuum circuit breaker V2 connects the fixed terminal T2 of the transfer switch T and the N+1 tap side of the switching circuit, and is connected in parallel with the main switch M2;
[0010] The transition resistor R is connected to one end of the vacuum circuit breaker V3 and the fixed end T3 of the changeover switch;
[0011] The on-load tap changer switches between the N tap side and the N+1 tap side of the switching circuit.
[0012] Optionally, during the transition of the switching circuit, the timing of switching from the N tap side to the N+1 tap side and the timing of switching from the N+1 tap side to the N tap side are symmetrical timing.
[0013] Optionally, when the on-load tap changer is in the N-tap side of the switching circuit, the main switch M1 is closed, the main switch M2 is open, the moving contact of the operating arm of the changeover switch T is connected to the fixed end T1, the vacuum circuit breaker V1 and the vacuum circuit breaker V3 are closed, and the vacuum circuit breaker V2 is open. At this time, the load current on the N-tap side of the switching circuit is output to the neutral point of the transformer through the main switch M1 and the changeover switch T.
[0014] Optionally, when the on-load tap changer is switched from the N tap side of the switching circuit to the N+1 tap side of the switching circuit, the operation process includes:
[0015] 1. When the main switch M1 is opened, the moving contact of the operating arm of the changeover switch T is simultaneously connected to the fixed terminals T1 and T2, the vacuum circuit breaker V1 is opened, and the vacuum circuit breaker V2 is closed.
[0016] 2. When the main switch M2 is closed, the vacuum circuit breaker V3 is opened, the moving contact of the operating arm of the transfer switch T is connected to the fixed end T2, and the vacuum circuit breakers V1 and V3 are closed.
[0017] Optionally, when the on-load tap changer is in the N+1 tap position of the switching circuit, the main switch M2 is closed, the main switch M1 is open, the moving contact of the operating arm of the changeover switch T is connected to the fixed end T2, and the vacuum circuit breakers V1, V2 and V3 are closed. At this time, the load current on the N+1 tap position of the switching circuit is output to the neutral point of the transformer through the main switch M2 and the changeover switch T.
[0018] This invention also proposes a control method for a switching circuit of a vacuum on-load tap changer, comprising:
[0019] When the on-load tap changer needs to connect to the N+1 tap side of the switching circuit, the main switch M2 is closed, the main switch M1 is opened, the moving contact of the changeover switch T is connected to the fixed end T2, and the vacuum circuit breakers V1, V2 and V3 are closed.
[0020] When the on-load tap changer needs to be connected to the N tap side of the switching circuit, the main switch M1 is closed, the main switch M2 is opened, the moving contact of the changeover switch T is connected to the fixed end T1, the vacuum circuit breaker V1 and vacuum circuit breaker V3 are closed, and the vacuum circuit breaker V2 is opened.
[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0022] This invention provides a switching circuit for a vacuum on-load tap changer, comprising: a main current-carrying switch M1, a main current-carrying switch M2, a changeover switch T, a vacuum circuit breaker V1, a vacuum circuit breaker V2, a vacuum circuit breaker V3, and a transition resistor R; the main switch M1 is connected to the N-tap side of the switching circuit and the transformer neutral point; the main switch M2 is connected to the N+1 tap side of the switching circuit and the transformer neutral point; the fixed end of the changeover switch T is connected to the transformer neutral point, and the actuating arm of the changeover switch T is connected to the main switch M1. Switching occurs between M1 and the main switch M2; the vacuum circuit breaker V1 connects to the fixed terminal T1 of the transfer switch T and one end of the vacuum circuit breaker V3, and is connected in parallel with the transition resistor R; the vacuum circuit breaker V2 connects to the fixed terminal T2 of the transfer switch T and the N+1 tap side of the switching circuit, and is connected in parallel with the main switch M2; the transition resistor R connects one end of the vacuum circuit breaker V3 and the fixed terminal T3 of the transfer switch; the on-load tap changer switches between the N tap side and the N+1 tap side of the switching circuit. The timing sequence of the switching circuit in this invention, from the N tap side to the N+1 tap side and from the N+1 tap side to the N tap side, is symmetrical, greatly simplifying the mechanical design. The use of symmetrical timing and a single transition resistor design saves on switch manufacturing costs. The task of passing and interrupting current during the switching process is undertaken by the three vacuum circuit breakers V1, V2, and V3, sharing and balancing the switching task of the vacuum circuit breaker. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the switching circuit of the present invention.
[0024] Figure 2a -h is a schematic diagram of the conversion from N tap side to N+1 tap side in this invention;
[0025] Figure 3 This is a schematic diagram of the present invention when it is on the N+1 tap side;
[0026] Figure 4 This is a timing diagram of the procedure for the conversion from the N tap side to the N+1 tap side in this invention. Detailed Implementation
[0027] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention. In the drawings, the same units / elements are referred to by the same reference numerals.
[0028] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.
[0029] This invention proposes a switching circuit for a vacuum on-load tap changer, such as... Figure 1 As shown, it includes: main current-carrying switch M1, main current-carrying switch M2, changeover switch T, vacuum circuit breaker V1, vacuum circuit breaker V2, vacuum circuit breaker V3, and transition resistor R;
[0030] The main switch M1 connects the N-tap side of the switching circuit to the neutral point of the transformer;
[0031] The main switch M2 connects the N+1 tap side of the switching circuit to the neutral point of the transformer;
[0032] The fixed end of the changeover switch T is connected to the neutral point of the transformer, and the actuating arm of the changeover switch T switches between the main switch M1 and the main switch M2.
[0033] The vacuum circuit breaker V1 connects the fixed terminal T1 of the transfer switch T and one end of the vacuum circuit breaker V3, and is connected in parallel with the transition resistor R.
[0034] The vacuum circuit breaker V2 connects the fixed terminal T2 of the transfer switch T and the N+1 tap side of the switching circuit, and is connected in parallel with the main switch M2;
[0035] The transition resistor R is connected to one end of the vacuum circuit breaker V3 and the fixed end T3 of the changeover switch;
[0036] The on-load tap changer switches between the N tap side and the N+1 tap side of the switching circuit.
[0037] In the transition process of the switching circuit, the timing of switching from the N tap side to the N+1 tap side and the timing of switching from the N+1 tap side to the N tap side are symmetrical timings.
[0038] When the on-load tap changer is in the N-tap side of the switching circuit, the main switch M1 is closed, the main switch M2 is open, the moving contact of the operating arm of the changeover switch T is connected to the fixed end T1, the vacuum circuit breaker V1 and the vacuum circuit breaker V3 are closed, and the vacuum circuit breaker V2 is open. At this time, the load current on the N-tap side of the switching circuit is output to the neutral point of the transformer through the main switch M1 and the changeover switch T.
[0039] When the on-load tap changer is switched from the N tap side of the switching circuit to the N+1 tap side, the operation process includes:
[0040] 1. When the main switch M1 is opened, the moving contact of the operating arm of the changeover switch T is simultaneously connected to the fixed terminals T1 and T2, the vacuum circuit breaker V1 is opened, and the vacuum circuit breaker V2 is closed.
[0041] 2. When the main switch M2 is closed, the vacuum circuit breaker V3 is opened, the moving contact of the operating arm of the transfer switch T is connected to the fixed end T2, and the vacuum circuit breakers V1 and V3 are closed.
[0042] When the on-load tap changer is in the N+1 tap position of the switching circuit, the main switch M2 is closed, the main switch M1 is open, the moving contact of the operating arm of the changeover switch T is connected to the fixed end T2, and the vacuum circuit breakers V1, V2 and V3 are closed. At this time, the load current on the N+1 tap position of the switching circuit is output to the neutral point of the transformer through the main switch M2 and the changeover switch T.
[0043] like Figure 1 As shown, when the on-load tap changer is in the N tap position, the main switch M1 is closed and M2 is open. The moving contact of the operating arm of the transfer switch T is connected to M1, the vacuum circuit breakers V1 and V3 are closed, and the vacuum circuit breaker V2 is open. At this time, the load current on the N tap side is output to the neutral point of the transformer through the main switch M1 and the transfer switch T.
[0044] When the tap changer is switched from the N tap side to the N+1 tap side, the operation steps of the transition circuit include:
[0045] like Figure 1 and Figure 2a As shown, when the main switch M1 is disconnected, the load current on the N tap side flows through the transfer switch T, the current circuit breakers V1 and V3 and is output to the neutral point of the transformer.
[0046] like Figure 1 and Figure 2b As shown, when the operating arm of the changeover switch T is operated, the moving contact of T is simultaneously connected to the stationary contacts on both sides. At this time, the load current on the N tap side is output to the neutral point of the transformer through the changeover switch T, the current circuit breakers V1 and V3.
[0047] like Figure 1 and Figure 2c As shown, the vacuum circuit breaker V1 is disconnected. At this time, the load current on the N tap side flows through the vacuum circuit breaker V3 and the transition resistor R to the transformer neutral point;
[0048] like Figure 1 and Figure 2d As shown, the vacuum circuit breaker V2 is closed. At this time, the transition circuit simultaneously connects the N tap side and the N+1 tap side, forming a bridge and generating a circulating current IC = US / R. The load current then shifts from the N tap side to the N+1 tap side. Here, US is the on-load tap changer stage voltage.
[0049] like Figure 1 and Figure 2e As shown, close the main switch M2. At this time, the load current on the N+1 tap side flows through the main switch M2 and is output to the transformer neutral point. The N tap side and the N+1 tap side are still bridged, and the circulating current IC still exists.
[0050] like Figure 1 and Figure 2f As shown, the vacuum circuit breaker V3 is disconnected. At this time, the bridging between the N tap side and the N+1 tap side is broken, and the connection between the N tap side and the neutral point is also broken. The load current on the N+1 side flows through the main switch M2 and is output to the transformer neutral point.
[0051] like Figure 1 and Figure 2g As shown, the operating arm of the changeover switch T is activated, connecting the moving contact of T to the stationary contact on the main switch M2 side. At this time, the current flow remains unchanged.
[0052] like Figure 1 and Figure 2h As shown, vacuum circuit breakers V1 and V3 are closed. At this time, the current flow remains unchanged, and closing circuit breakers V1 and V3 prepares for the next switching task.
[0053] like Figure 3 As shown, when the on-load tap changer is in the N+1 tap position, the main switch M2 is closed and M1 is open. The moving contact of the operating arm of the transfer switch T is connected to the tap of M2. The vacuum circuit breakers V1, V2 and V3 are closed. At this time, the load current on the N+1 tap side is output to the neutral point of the transformer through the main switch M2.
[0054] The principle and process of switching from N+1 tap to N tap are the same, so they will not be described in detail here.
[0055] When the tap selector switches from N tap to N+1 tap, the transition circuit switching timing diagram is as follows: Figure 4 As shown.
[0056] This invention also proposes a control method for a switching circuit of a vacuum on-load tap changer, comprising:
[0057] Step 1: When the on-load tap changer needs to connect to the N+1 tap side of the switching circuit, close the main switch M2, open the main switch M1, connect the moving contact of the operating arm of the changeover switch T to the fixed end T2, and close the vacuum circuit breakers V1, V2 and V3.
[0058] Step 2: When the on-load tap changer needs to be connected to the N tap side of the switching circuit, close the main switch M1, open the main switch M2, connect the moving contact of the operating arm of the changeover switch T to the fixed end T1, close the vacuum circuit breaker V1 and the vacuum circuit breaker V3, and open the vacuum circuit breaker V2.
[0059] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0060] The switching circuit of this invention features symmetrical timing for switching from the N-tap side to the N+1-tap side and from the N+1-tap side to the N-tap side, significantly simplifying the mechanical design. The use of symmetrical timing, coupled with a single transition resistor design, reduces switch manufacturing costs. The switching process, including both current flow and interruption, is handled by three vacuum circuit breakers V1, V2, and V3, thus sharing and balancing the switching load of the vacuum bulb.
[0061] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.
[0062] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.
[0063] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1The function specified in one or more boxes.
[0064] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.
[0065] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.
[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A switching circuit for a vacuum on-load tap changer, characterized in that, The switching circuit includes: main switch M1, main switch M2, changeover switch T, vacuum circuit breaker V1, vacuum circuit breaker V2, vacuum circuit breaker V3, and transition resistor R; The main switch M1 connects the N-tap side of the switching circuit to the neutral point of the transformer; The main switch M2 connects the N+1 tap side of the switching circuit to the neutral point of the transformer; The neutral point of the changeover switch T is connected to the neutral point of the transformer, and the actuating arm of the changeover switch T switches between the main switch M1 and the main switch M2. The vacuum circuit breaker V1 is connected to the T1 terminal of the transfer switch T and one end of the vacuum circuit breaker V3, and is connected in parallel with the transition resistor R; The vacuum circuit breaker V2 is connected to the T2 terminal of the transfer switch T and the N+1 tap side of the switching circuit, and is connected in parallel with the main switch M2; The transition resistor R is connected to one end of the vacuum circuit breaker V3 and the T1 end of the changeover switch; The on-load tap changer switches between the N tap side and the N+1 tap side of the switching circuit. During the transition process of the switching circuit, the timing sequence of switching from the N tap side to the N+1 tap side and the timing sequence of switching from the N+1 tap side to the N tap side are symmetrical timing sequences. When the on-load tap changer is in the N-tap side of the switching circuit, the main switch M1 is closed and the main switch M2 is open. The moving contact of the operating arm of the changeover switch T is connected to the T1 terminal. Vacuum circuit breakers V1 and V3 are closed and vacuum circuit breaker V2 is open. At this time, the load current on the N-tap side of the switching circuit is output to the transformer neutral point through the main switch M1 and the changeover switch T. When the on-load tap changer is switched from the N-tap side of the switching circuit to the N+1-tap side of the switching circuit, the operation process includes:
1. When the main switch M1 is opened, the moving contact of the operating arm of the changeover switch T is simultaneously connected to the T1 and T2 terminals, the vacuum circuit breaker V1 is opened, and the vacuum circuit breaker V2 is closed.
2. When the main switch M2 is closed, the vacuum circuit breaker V3 is opened, the moving contact of the operating arm of the changeover switch T is connected to the T2 terminal, and the vacuum circuit breakers V1 and V3 are closed. When the on-load tap changer is in the N+1 tap position of the switching circuit, the main switch M2 is closed, the main switch M1 is open, the moving contact of the operating arm of the changeover switch T is connected to the T2 terminal, and the vacuum circuit breakers V1, V2 and V3 are closed. At this time, the load current on the N+1 tap position of the switching circuit is output to the transformer neutral point through the main switch M2 and the changeover switch T.