Tap changer for use under arc-free load conditions, and switching control method.

Abstract

The present invention belongs to the technical field of power transmission and transformation in a power system, and provides an arc-free on-load tap changer, a switching control method, and an electric device. The arc-free on-load tap changer includes at least two master switches, two changeover switches, and two thyristor auxiliary modules. The two thyristor auxiliary modules are connected in parallel to the master switch that is originally turned on or the master switch that should be turned on according to the required timing during the switching process of the master switch. The master switch and the changeover switch are both rotary switches, and the movable contacts of the master switch and the changeover switch are both mounted on a rotating shaft, and the corresponding fixed contacts of the master switch and the changeover switch are connected to the corresponding transformer tap, and the movable contacts are connected to the fixed contacts of the same shaft during the process of rotating together with the rotating shaft. The opening and closing of the corresponding master switch, the changeover switch, and the control switch are controlled according to a predetermined timing, thereby realizing an uninterrupted transfer of the load current from the master switch that is originally turned on to the master switch that should be turned on, and no arc occurs during the opening and closing process of each switch.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This invention claims priority to a Chinese patent application filed with the Chinese National Patent Office on March 9, 2022, application number 202210232941.2, with the title of the invention "Arc-free load tap changer, switching control method, and electrical equipment," the entirety of which is incorporated into this invention by reference.

[0002] The present invention belongs to the technical field of power transmission and distribution for power systems, and more particularly relates to tap changers for use under arc-free loads, a switching control method, and electrical equipment. [Background technology]

[0003] This section merely provides background information related to the present invention and does not necessarily constitute prior art.

[0004] Under conditions where a transformer has a load current (under load), in order to switch a specific voltage tap on the transformer to another voltage tap and ensure that power supply to electricity users is not interrupted during the switching, the use of an on-load tap changer is necessary. Here, an on-load tap changer refers to a voltage adjustment device that changes the connection position of the transformer winding taps to suit the excitation or operation of the transformer under load. Its basic principle is to enable switching between taps in the transformer windings while ensuring that the load current is not interrupted, thereby changing the number of turns in the windings, i.e., the voltage ratio of the transformer, and ultimately achieving the purpose of voltage adjustment.

[0005] Conventional on-load tap changers typically use a resistive transition method to switch between two taps with different voltages. However, the resistive transition method has the disadvantage of generating an electric arc during the switching process.

[0006] Each of the patent documents with application numbers CN2012105791965, CN2013105976862, and CN2014102602640 provides different arc-free load tap changers. However, since oil-filled load tap changers are suitable for drive by a rotating shaft, and the inventors have found that the devices proposed in the above-mentioned applications are mainly used when the circuit is composed of contactors or relay contacts, arc-free load tap changers composed of contactors or relays are not suitable for use in oil-filled transformers.

[0007] The solution for an on-load tap changer provided in the patent document with application number CN2018102904704 includes a structure driven by a rotating shaft. However, the inventors found that in this patent document, various switches are distributed on two or three rotating shafts that are not synchronized, and when it is necessary to rotate some of the rotating shafts, it is necessary to keep the other rotating shafts stationary, resulting in a complex operating structure. Furthermore, the invention lacks a cooperative control mechanism between the rotating shafts, a means for coordinating the movable and fixed contacts of the rotating shafts, and a means for driving the control switches. [Overview of the project]

[0008] To solve the technical problems present in the background technology described above, the present invention provides an arc-free load tap changer, a switching control method, and electrical equipment applicable to an oil-immersed transformer driven by a rotating shaft, which have the advantages of a simple operating structure and a short time required to perform a complete switching process in one go.

[0009] To achieve the above objectives, the present invention employs the following technical solutions.

[0010] A first aspect of the present invention provides a tap changer for use with no arc load.

[0011] In one or more embodiments, the system includes at least two master switches, two changeover switches, and two thyristor auxiliary modules, each thyristor auxiliary module including two control switches, and the two master switches including one originally-on master switch and one to-on master switch, the master switches being connected to corresponding circuits of a voltage regulating coil via corresponding transformer taps, and the two thyristor auxiliary modules being connected in parallel to the originally-on master switch or the to-on master switch as needed during the switching process of the master switches. The master switch and the changeover switch are both rotary switches, the movable contacts of the master switch and the changeover switch are both provided on the rotating shaft, the corresponding fixed contacts of the master switch and the changeover switch are connected to the corresponding transformer taps, the movable contacts are connected to the coaxial fixed contacts in the process of rotating with the rotating shaft, and by controlling the opening and closing of the corresponding master switch, changeover switch and control switch according to predetermined timing, a seamless transfer of load current from the master switch that was originally on to the master switch that should be turned on is achieved, and no electric arc is generated during the opening and closing process of each switch, providing a structure for a first arc-free load tap changer.

[0012] In one embodiment, one end of each of the two thyristor auxiliary modules is either floating before the master switch is switched over, or connected in parallel to the master switch which was originally turned on, and the voltage across both ends of the two thyristor auxiliary modules is zero.

[0013] In one embodiment, the control switch is also a rotary switch, and the movable contact of the control switch is also provided on the rotating shaft.

[0014] In one embodiment, all the fixed contacts of both the master switch and the changeover switch are divided into at least two sets in total, and the fixed contacts of each set are mounted on a corresponding rail, and each rail is fixed so as not to move around a rotation axis.

[0015] In one embodiment, the number of fixed contacts per set is the same.

[0016] In one embodiment, each set of fixed contacts is mounted on the corresponding rail at equal arc angles.

[0017] In one embodiment, if all the fixed contacts of both the master switch and the changeover switch are divided into two sets in total, the relationship between the radii of the fixed contacts on the two corresponding rails is: 0 < ΔW <W1<0.5W<W2 ΔW=(W-W2) Here, W and W1 are the radians between the center positions of each fixed contact on the first rail and the radians of each fixed contact, respectively, and W2 and ΔW are the radians of each fixed contact on the second rail and the radians of the gap between the fixed contacts, respectively.

[0018] In one embodiment, before switching the master switch, the normal operating state of the tap changer under no-arc load conditions is as follows: One movable contact on the axis of rotation is located on the center line of one fixed contact, and the remaining movable contacts are each located on the center line of the gap between the fixed contacts.

[0019] In one embodiment, if there are a total of three movable contacts on the axis of rotation, the first and second movable contacts are positioned on either side of the third movable contact, and the relationship of the radii of the three movable contacts is as follows: 0 < ΔW <W 1可動 <0.5W <W 2可動 ΔW 可動 =(WW 2可動 ) Here, W is the arc between the center positions of each fixed contact on the first rail, 1可動 , W 2可動 ΔW is the arc of the first and second movable contacts. 可動 This is the arc of the gap between the second movable contacts.

[0020] In one embodiment, the radii of the fixed contact are greater than the radii of the movable contact.

[0021] In one embodiment, the radian of the fixed contact is less than or equal to the radian of the movable contact.

[0022] In one embodiment, the opening and closing of the control switch is controlled by a control mechanism.

[0023] In one embodiment, the control mechanism is a mechanical interlocking mechanism.

[0024] In one embodiment, the mechanical interlocking mechanism includes a deflection shaft. The deflection shaft is fixed to the rotation shaft and rotates with the rotation shaft. A lever arm and a spring arm that are rotatable around the deflection shaft are attached to the deflection shaft. There is a contact at one end of the spring arm. The contact rotates with the rotation shaft and contacts or disengages from the corresponding control switch to open and close the corresponding control switch.

[0025] In one embodiment, the control mechanism is realized by a changeover switch driven by a rotation shaft.

[0026] In one embodiment, the structures of the two thyristor auxiliary modules are the same.

[0027] In one embodiment, each thyristor auxiliary module includes a pair of thyristors connected in parallel in reverse directions, with an RC series circuit connected in parallel to both ends of the thyristors connected in parallel in reverse directions. A capacitor, a resistor, and a diode are sequentially connected between the gate and cathode of each thyristor, with the positive terminal of the diode connected to the cathode of the corresponding thyristor and the negative terminal of the diode connected to the gate of the corresponding thyristor. A control switch is further connected in series between the gates of the two thyristors connected in parallel in reverse directions via a full-bridge rectifier circuit. Two Zener diodes, a resistor, and another control switch are sequentially connected in series in reverse directions between the gates of the two thyristors connected in parallel in reverse directions. The two Zener diodes are connected in series in reverse directions, and the Zener diodes and resistor are connected in series and then connected to the output terminal of the full-bridge rectifier circuit. The negative terminal of the Zener diode corresponds to the positive output terminal of the full-bridge rectifier circuit, and the positive terminal of the Zener diode corresponds to the negative output terminal of the full-bridge rectifier circuit.

[0028] The present invention includes at least two master switches, two changeover switches, and two thyristor auxiliary modules, each thyristor auxiliary module including two control switches, and the two master switches including one originally on master switch and one to be turned on, the master switches being connected to corresponding circuits of voltage regulating coils via corresponding transformer taps, and the two thyristor auxiliary modules being connected to the originally on master switch or the master switch to be turned on at the required timing during the switching process of the master switches. The present invention provides a second arc-free load tap changer, characterized in that both the master switch and the changeover switch are rotary switches, the master switch and the corresponding changeover switch rotate in conjunction and synchronously, and by controlling the opening and closing of the corresponding master switch, changeover switch and control switch according to a predetermined timing, a seamless transfer of load current from the master switch that was originally on to the master switch that should be turned on is achieved, and no electric arc is generated during the opening and closing process of each switch.

[0029] In one embodiment, the control mechanism is a mechanical interlocking mechanism.

[0030] In one embodiment, the mechanical interlocking mechanism includes a deflection shaft, which is fixed to and rotates with the rotation shaft, and a lever arm and a spring arm are attached to the deflection shaft, which are rotatable around the deflection shaft, and one end of the spring arm has a contact, which rotates with the rotation shaft and makes contact with or disengages from a corresponding control switch to open or close the corresponding control switch.

[0031] In one embodiment, the control mechanism is realized by a changeover switch driven by a rotating shaft.

[0032] In one embodiment, the structures of the two thyristor auxiliary modules are identical.

[0033] In one embodiment, each thyristor auxiliary module includes a pair of thyristors connected in parallel in reverse directions, with an RC series circuit connected in parallel to both ends of the thyristors connected in parallel in reverse directions. A capacitor, a resistor, and a diode are sequentially connected between the gate and cathode of each thyristor, with the positive terminal of the diode connected to the cathode of the corresponding thyristor and the negative terminal of the diode connected to the gate of the corresponding thyristor. A control switch is further connected in series between the gates of the two thyristors connected in parallel in reverse directions via a full-bridge rectifier circuit. Two Zener diodes, a resistor, and another control switch are sequentially connected in series in reverse directions between the gates of the two thyristors connected in parallel in reverse directions. The two Zener diodes are connected in series in reverse directions, and the Zener diodes and resistor are connected in series and then connected to the output terminal of the full-bridge rectifier circuit. The negative terminal of the Zener diode corresponds to the positive output terminal of the full-bridge rectifier circuit, and the positive terminal of the Zener diode corresponds to the negative output terminal of the full-bridge rectifier circuit.

[0034] A second aspect of the present invention provides a method for controlling the switching of a tap changer under arc-free load conditions.

[0035] In one or more embodiments, the switching control method for a first arc-free load tap changer provided by the present invention is: A step of controlling the rotation axis to rotate and driving the movable contact to connect to or disconnect from the corresponding fixed contact, The method includes a step of controlling the opening and closing of the corresponding master switch, changeover switch, and control switch according to a predetermined timing, thereby achieving a seamless transfer of load current from the master switch that was originally on to the master switch that should be turned on, and ensuring that no electric arcs are generated during the opening and closing process of each switch.

[0036] In one embodiment, the rotation method of the rotating shaft includes clockwise rotation and counterclockwise rotation.

[0037] In one embodiment, the process of switching the master switch once is: By bringing the movable contact of the corresponding changeover switch into contact with the corresponding fixed contact, the first control switch of the thyristor auxiliary module connected to the originally on master switch is turned on, and the originally on master switch is turned off. This involves turning on the second control switch of the thyristor auxiliary module connected to the master switch that should be turned on, and turning off the first control switch of the thyristor auxiliary module connected to the master switch that was originally turned on, When the set time interval has elapsed, the first control switch of the thyristor auxiliary module connected to the master switch that should be turned on is turned on, and the master switch that should be turned on is turned on. This includes turning off all control switches, ensuring that the movable contacts of the corresponding changeover switches no longer contact the corresponding fixed contacts, and completing one master switch changeover.

[0038] In one embodiment, the voltage across both ends of the two thyristor auxiliary modules is set to zero before the master switch is switched.

[0039] The switching control method for a second tap changer under no-arc load conditions provided by the present invention is: The steps include controlling the opening and closing of the corresponding master switch and changeover switch so that they rotate in conjunction and in sync, The method includes a step of controlling the opening and closing of the corresponding master switch, changeover switch, and control switch according to a predetermined timing, thereby achieving a seamless transfer of load current from the master switch that was originally on to the master switch that should be turned on, and ensuring that no electric arcs are generated during the opening and closing process of each switch.

[0040] A third aspect of the present invention provides an electrical device.

[0041] In one or more embodiments, the electrical equipment is A voltage regulating coil including multiple transformer taps, The system includes a tap changer for use with no electric loads connected to the voltage adjustment coil, The aforementioned arc-free load tap changer is the arc-free load tap changer described in any one of the above items.

[0042] Compared to the conventional technology, the beneficial effects of the present invention are as follows:

[0043] (1) The arc-free tap changer provided by the present invention solves the problem that conventional arc-free tap changers are unsuitable for use in oil-filled transformers by mounting a movable contact on a rotating shaft and rotating it together with the rotating shaft to connect to the corresponding fixed contact. The arc-free tap changer according to the present invention uses a rotating shaft as the driving power and controls the opening and closing of the master switch, changeover switch, control switch and master switch to be turned on, which were originally on, in correspondence with each other according to a predetermined timing, thereby preventing the generation of electric arcs during the opening and closing process and enabling switching between master switches, thereby allowing various switches and contacts to be operated within the oil tank of an oil-filled transformer.

[0044] (2) The tap changer for non-arc loads provided by the present invention can be realized based on the basic structure of a conventional oil-filled tap changer for loads, and it can also be realized based on the basic structure of a conventional oil-filled non-excitation tap changer.

[0045] (3) In the arc-free tap changer provided by the present invention, the changeover switch includes a plurality of fixed contacts, the corresponding fixed contacts of the changeover switch are connected to the transformer tap, and at least one control switch is mounted on a rotating shaft and driven by the rotating shaft to control opening and closing, thereby building upon the basic structure of a conventional oil-immersed vacuum-loaded tap changer, upgrading the oil-immersed vacuum-loaded tap changer to achieve no arc generation during the opening and closing process and switching between master switches.

[0046] (4) The tap changer for use under non-arc load conditions according to the present invention retains the experience gained from previous inventions, has a simplified structure, is smaller in volume, lighter in weight, reduces costs, has less operating vibration, a lower failure rate, and a shorter time required to perform a complete switching process in one go.

[0047] Additional advantages of the present invention are, in part, set forth in the following description, in part, become obvious from the following description, or are understood through the practice of the present invention. [Brief explanation of the drawing]

[0048] The drawings in the specification, which constitute a part of the present invention, are for further understanding of the present invention, and the exemplary embodiments and descriptions thereof are for interpretation of the present invention and are not intended to unduly limit the present invention. [Figure 1] This is a circuit diagram of a thyristor auxiliary module according to an embodiment of the present invention. [Figure 2] This is a structural diagram of the rotating shaft of the first arc-free load tap changer according to an embodiment of the present invention. [Figure 3] This is a horizontally unfolded structural diagram of the first arc-free load tap changer according to an embodiment of the present invention. [Figure 4] This is a diagram showing the relationship between the radians of the fixed contacts in an embodiment of the present invention. [Figure 5] This is a structural diagram of switches KB1 and KB2 according to an embodiment of the present invention. [Figure 6] This is a structural diagram of the rotating shaft of a second arc-free load tap changer according to an embodiment of the present invention. [Modes for carrying out the invention]

[0049] The present invention will be further described below with reference to the drawings and embodiments.

[0050] It should be noted that the following detailed descriptions are illustrative and intended to further illustrate the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the invention pertains.

[0051] It should be noted that the terms used herein are merely for the purpose of describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. For example, unless otherwise specified in the context, the singular form used herein is intended to include plural forms, and it should also be understood that when the terms “contains” and / or “includes” are used in this description, it indicates the presence of features, processes, operations, devices, assemblies and / or combinations thereof. <Tap changer and switching control method for use under arc-free load conditions>

[0052] In the background technology, conventional tap changers for use with non-arc loads are unsuitable for use with oil-filled transformers. Even if they are suitable for oil-filled transformers, the various switches are distributed across two or three non-synchronous rotating shafts, and when it is necessary to rotate some of the rotating shafts, it is necessary to keep the other rotating shafts stationary, resulting in a complex operating structure. Furthermore, they lack a coordinated control mechanism for the rotating shafts, a means of cooperation between the movable and fixed contacts of the rotating shafts, and a means of driving the control switches. To solve these problems, the present invention provides a tap changer for use with non-arc loads and a corresponding switching control method. [Examples]

[0053] This embodiment includes at least two master switches, two changeover switches, and two thyristor auxiliary modules, each thyristor auxiliary module including two control switches, and the two master switches including one originally on master switch and one to be turned on, the master switches being connected to corresponding circuits of voltage regulating coils via corresponding transformer taps, and the two thyristor auxiliary modules being connected in parallel to the originally on master switch or the master switch to be turned on, depending on the timing required during the switching process of the master switches. The master switch and changeover switch are both rotary switches, the movable contacts of the master switch and changeover switch are both mounted on the rotating shaft, the corresponding fixed contacts of the master switch and changeover switch are connected to the corresponding transformer taps, the movable contacts are connected to the coaxial fixed contacts as they rotate with the rotating shaft, and by controlling the opening and closing of the corresponding master switch, changeover switch and control switch according to predetermined timing, a seamless transfer of load current from the originally ON master switch to the master switch to be ON is achieved, and no electric arc is generated during the opening and closing process of each switch, providing an arc-free load tap changer.

[0054] The arc-free tap changer of this embodiment is powered by a rotating shaft, is suitable for oil-filled transformers, and is configured so that the contacts rotate and slide. Its structure is as shown in Figure 2. Oil-filled tap changers are generally three-phase tap changers that are mounted on the same insulated rotating shaft, have the same structure, and are driven synchronously by the rotating shaft. For the sake of explanation, Figure 2 uses a three-tap single-phase oil-filled tap changer as an example.

[0055] In this embodiment, the control switch is also a rotary switch, and the movable contact of the control switch is also provided on the rotating shaft.

[0056] All fixed contacts of both the master switch and the changeover switch are divided into at least two sets in total, and each set of fixed contacts is mounted on a corresponding rail, which is fixed around a rotation axis and does not move. Here, the rail is a circular insulating frame, and the insulating frame does not move with the rotation axis. The movable contacts are mounted on the rotation axis and rotate with the rotation axis.

[0057] Here, before the tap changer for non-arc loads switches, one end of each thyristor auxiliary module is either floating or connected in parallel to the master switch which was originally on. Before the tap changer for non-arc loads switches, the voltage across both ends of each thyristor auxiliary module is zero.

[0058] During the switching process of the tap changer for use when there is no arc load, the thyristor auxiliary module is connected in parallel to the master switch that was originally turned on, or to the master switch that should be turned on, depending on the timing required.

[0059] In this embodiment, we will explain using the example of a configuration with two sets of fixed contacts, meaning there are two rails, each set having three fixed contacts, and three movable contacts.

[0060] To make this clear, in another embodiment, a person skilled in the art may specifically set the number of movable contacts and the number of fixed contact sets according to the actual situation.

[0061] In this embodiment, the first rail has three fixed contacts arranged sequentially, and the radian of the distance between the center positions of the first and second fixed contacts on the first rail is equal to W, and the radian of the distance between the center positions of the second and third fixed contacts on the first rail is also equal to W. The second rail also has fixed contacts, and the number of fixed contacts on the second rail is equal to the number of fixed contacts on the first rail. The center line of each fixed contact on the first rail coincides with the center line of one fixed contact on the second rail, and the fixed contacts on the first rail and the fixed contacts on the second rail where the center lines coincide are connected, and are sequentially connected to taps I, II, and III of the transformer coil L1, respectively.

[0062] The radii of the three fixed contacts on the first rail are the same and equal to W1, the radii of the three fixed contacts on the second rail are the same and equal to W2, and the radii of the gap between the fixed contacts on the second rail are the same. ΔW is equal to (W - W2). For convenience of explanation, the structural diagram of the rotating shaft of the tap changer under no-arc load in FIG. 2 is horizontally unfolded as shown in FIGS. 3 and 4. It is required that 0 < ΔW < W1 < 0.5W < W2.

[0063] In this embodiment, there are three movable contacts, namely movable contact J3, movable contact Q1, and movable contact Q2, on the rotating shaft. The movable contacts are attached to the rotating shaft and rotate together with the rotating shaft. Here, movable contact Q1 and movable contact Q2 are provided on both sides of movable contact J3 respectively.

[0064] While movable contact J3 rotates together with the rotating shaft, it connects to or disconnects from the three fixed contacts on the first rail in sequence respectively, to realize the on and off of the master switch. While movable contact Q1 and movable contact Q2 rotate together with the rotating shaft, they connect to or disconnect from the three fixed contacts on the second rail in sequence respectively, to realize the conversion of the changeover switch. The center position of movable contact Q1 is on the second rail on the left side of the center of movable contact J3, and the included angle between the two is 0.5W. The center position of movable contact Q2 is on the second rail on the right side of the center of movable contact J3, and the included angle between the two is 0.5W.

[0065] The normal operating state before switching of the tap changer under no-arc load in this embodiment is that the movable contact J3 on the rotating shaft is on the center line of the fixed contact W1, and the movable contact Q1 and the movable contact Q2 are on the center lines of the gaps respectively.

[0066] In this embodiment, the thyristor auxiliary module M1 and the thyristor auxiliary module M2 have the same circuit, and the main circuit of each thyristor auxiliary module includes a pair of thyristors connected in parallel in the opposite direction, and the RC series circuit is connected in parallel to both ends of the thyristors connected in parallel in the opposite direction, and a capacitor, resistor and diode are connected between the gate and cathode of each thyristor, the positive terminal of the diode is connected to the cathode of the corresponding thyristor and the negative terminal of the diode is connected to the gate of the corresponding thyristor, and the two thyristors connected in parallel in the opposite direction Between the gates of the thyristors, one control switch is connected in series via a full-bridge rectifier circuit. Between the gates of two thyristors connected in parallel in the opposite direction, two Zener diodes, one resistor, and another control switch are sequentially connected in series in the opposite direction. The Zener diodes and resistor are connected in series and then connected to the output terminal of the full-bridge rectifier circuit. The negative terminal of the Zener diode corresponds to the positive output terminal of the full-bridge rectifier circuit, and the positive terminal of the Zener diode corresponds to the negative output terminal of the full-bridge rectifier circuit.

[0067] Specifically, as shown in Figure 1, the main circuit of each thyristor auxiliary module includes a pair of thyristors D1 and D2 connected in parallel in reverse direction. Resistor R1 and capacitor C1 are connected in series, then in parallel across both ends of the thyristors D1 and D2 which are connected in parallel in reverse direction. Capacitors C3 and C4, resistors R3 and R4, and diodes D3 and D4 are connected in parallel to the gates and cathodes of the two thyristors D1 and D2, respectively. The positive terminals of diodes D3 and D4 are connected to the cathodes of thyristors D1 and D2, respectively, and the negative terminals of diodes D3 and D4 are connected to the gates of thyristors D1 and D2, respectively. Zener diodes D10 and D11 are connected in series in reverse direction, then in series with resistor R5, then in series with control switch KA, and subsequently connected between the gates of the two thyristors D1 and D2. The input terminals of the full-bridge rectifier circuit, consisting of diodes D5, D6, D7, and D8, are connected in series to the control switch KB, and then connected between the gates of two thyristors D1 and D2. The Zener diode D9 and resistor R6 are connected in series, and then connected to the output terminal of the full-bridge rectifier circuit. The negative terminal of Zener diode D9 corresponds to the positive output terminal of the full-bridge rectifier circuit, and the positive terminal of Zener diode D9 corresponds to the negative output terminal of the full-bridge rectifier circuit. The stable voltage of Zener diode D9 is U1 = k1U2, where k1 is the reliability factor, with a value of 1.2 to 2, and U2 is the peak of the adjustment interval voltage of the voltage regulator transformer. It is recommended to set the stable voltage of Zener diodes D10 and D11 to 1 to 3 volts.

[0068] It should be explained that the specific operating process of the thyristor auxiliary module is disclosed in patent document number CN201810290470.4, and a detailed explanation will be omitted here.

[0069] In this embodiment, the thyristor auxiliary module M1 is connected to control switches KA1 and KB1, and the thyristor auxiliary module M2 is connected to control switches KA2 and KB2.

[0070] The movable contact J3 is connected to a common terminal, both ends of the main circuit of the thyristor auxiliary module M1 are connected to the movable contact Q1 and a common terminal, and both ends of the main circuit of the thyristor auxiliary module M2 are connected to the movable contact Q2 and a common terminal.

[0071] In the specific implementation process, control switches KA1 and KA2 are mounted on the rotating shaft, and when each of the control switches KA1 and KA2 rotates with the rotating shaft, it can form two concentric rails called the third rail and the fourth rail, respectively. In the third rail, between the center line of the first fixed contact in the first rail and the center line of the second fixed contact in the first rail, there is a fixed contact W3, and in the fourth rail, there is a fixed contact W4. Similarly, in the third and fourth rails, between the center line of the second fixed contact in the first rail and the center line of the third fixed contact in the first rail, there are repeated fixed contacts W3 and W4, as shown in Figure 4.

[0072] Control switch KA1 rotates with the rotation axis and turns on when it encounters fixed contact W3, and turns off when it moves away from fixed contact W3. Control switch KA2 rotates with the rotation axis and turns on when it encounters fixed contact W4, and turns off when it moves away from fixed contact W4. From this, it can be seen that fixed contacts W3 and W4 are not necessarily made of metal, as long as they can trigger the turning on of control switch KA1 or control switch KA2.

[0073] When the rotation axis is rotating clockwise, control switch KA1 must contact the fixed contact W3 before the movable contact J3 leaves the fixed contact W1, and only after the movable contact J3 leaves the fixed contact W1 can control switch KA1 leave the fixed contact W3. Control switch KA2 must contact the fixed contact W4 before the movable contact J3 leaves another fixed contact W1, and only after the movable contact J3 leaves another fixed contact W1 can control switch KA2 leave the fixed contact W4. Furthermore, after control switch KA1 leaves the fixed contact W3, control switch KA2 can only make contact with the fixed contact W4 after at least a time interval t1 has elapsed.

[0074] When the rotation axis is rotating counterclockwise, the control switch KA2 must contact the fixed contact W4 before the movable contact J3 leaves the fixed contact W1, and only after the movable contact J3 leaves the fixed contact W1 can the control switch KA2 leave the fixed contact W4. The control switch KA1 must contact the fixed contact W3 before the movable contact J3 leaves another fixed contact W1, and only after the movable contact J3 leaves another fixed contact W1 can the control switch KA1 leave the fixed contact W3. Furthermore, after the control switch KA2 leaves the fixed contact W4, the control switch KA1 can only make contact with the fixed contact W3 after at least a time interval t1 has elapsed.

[0075] To ensure that the time interval t1 is greater than the set time (e.g., 0.015 seconds), the rotation of the axis of rotation should not be too fast. If the time it takes for the axis of rotation to complete one revolution is T seconds, T > ((0.015 × 2π) / (W2 - W3 - W4)).

[0076] Here, W2 is the radian of each fixed contact point on the second rail, and W3 and W4 are the radians of each fixed contact point on the third and fourth rails, respectively.

[0077] In this embodiment, the rotating shaft is further equipped with a control mechanism. When the rotating shaft is rotating clockwise, the control mechanism must ensure that control switch KB1 is turned off and control switch KB2 is turned on before KA1 separates from the fixed contact W3. When the rotating shaft is rotating counterclockwise, the control mechanism must ensure that control switch KB1 is turned on and control switch KB2 is turned off before KA2 separates from the fixed contact W3.

[0078] The switching control principle of the tap changer under arc-free load conditions in this embodiment is: Controlling the rotation axis to rotate and driving the movable contact to connect to or disconnect from the corresponding fixed contact, The opening and closing of the corresponding master switch, changeover switch, and control switch is controlled according to predetermined timings, thereby achieving a seamless transfer of load current from the originally ON master switch to the master switch to be ON, and preventing the generation of electric arcs during the opening and closing process of each switch.

[0079] Here, the rotation method of the rotating shaft includes clockwise rotation and counterclockwise rotation.

[0080] In this embodiment, the process of switching the master switch once is as follows: The movable contacts of the two selector switches are brought into contact with the fixed contacts, and the two thyristor auxiliary modules are connected in parallel to the master switch that was originally on or the master switch that should be turned on. The first control switch connected to the thyristor auxiliary module connected in parallel to the master switch that was originally on is turned on, and the master switch that was originally on is turned off. This involves turning on the second control switch connected to the thyristor auxiliary module, which is connected in parallel to the master switch that should be turned on, and turning off the first control switch, which is connected to the thyristor auxiliary module, which is connected in parallel to the master switch that was originally turned on. When the set time interval has elapsed, the first control switch connected to the thyristor auxiliary module, which is connected in parallel to the master switch that should be turned on, is turned on, and the master switch that should be turned on is turned on. This includes turning off all control switches, ensuring that the movable contacts of the two changeover switches no longer make contact with the fixed contacts, and completing one master switch changeover.

[0081] Referring to Figure 2, in this embodiment, the process for switching the master switch once is as follows:

[0082] (1) The movable contacts Q1 and Q2 are brought into contact with the two fixed contacts W2, and the control switch KA of the thyristor auxiliary module, which is connected in parallel to the master switch that was originally on, is turned on. (2) Turn off the master switch which was originally on, (3) Turn on the control switch KB of another thyristor auxiliary module connected in parallel to the master switch that should be turned on, (4) Turn off the control switch KA of the thyristor auxiliary module which is connected in parallel to the master switch that was originally turned on. (5) When a time interval t1 (where the time interval t1 is greater than 0.015 seconds) has elapsed, the control switch KA of the thyristor auxiliary circuit connected in parallel to the master switch to be turned on is turned on. (6) Turn on the master switch that should be turned on, (7) Turn off all control switches on the thyristor auxiliary module. (8) The movable contacts Q1 and Q2 no longer make contact with the fixed contact W2. (9) One master switch switching is completed.

[0083] The process of switching the master switch of this embodiment once will be explained below with reference to Figure 2, using clockwise and counterclockwise rotation of the rotation axis.

[0084] The switching control process for the tap changer in this embodiment when rotating clockwise under no-arc load conditions is as follows:

[0085] (1) The movable contact J3 begins to rotate clockwise from the center line position of the fixed contact W1 it is in contact with, the movable contact Q1 comes into contact with the fixed contact W2 connected to the fixed contact W1 that the movable contact J3 is in contact with, the movable contact Q2 comes into contact with the fixed contact W2 connected to the fixed contact W1 that the movable contact J3 is supposed to come into contact with, the control switch KA1 of the thyristor auxiliary module M1 comes into contact with the fixed contact W3, the control switch KA1 turns on, the load current continues to flow through the movable contact J3 from the fixed contact W1 that the movable contact J3 is in contact with, without any change in the flow path, to the common terminal, (2) The movable contact J3 separates from the fixed contact W1 to which it was originally in contact, and the load current flows from the fixed contact W2 connected to the fixed contact W1 to the movable contact Q1, through the thyristor auxiliary module M1 to the common terminal. (3) The control switch KB2 of the thyristor auxiliary module M2 is turned on, and the load current flow path does not change. (4) The control switch KA1 of the thyristor auxiliary module M1 is released from the fixed contact W3, the control switch KA1 is turned off, and each zero-crossing point of the load current triggers the thyristor auxiliary module M2 once, causing the load current to flow from the fixed contact W2 connected to the fixed contact W1 to be contacted, through the movable contact Q2 and the thyristor auxiliary module M2 to the common terminal. (5) After the time interval t1 has elapsed, the control switch KA2 of the thyristor auxiliary module M2 contacts the fixed contact W4, the control switch KA2 turns on, and the load current flow path does not change. (6) The movable contact J3 contacts the fixed contact W1 that it is to contact, and the load current flows from the fixed contact W1 that the movable contact J3 contacts through the movable contact J3 to the common terminal. (7) When the movable contacts Q1 and Q2 no longer make contact with the fixed contact W2, the control switch KA2 of the thyristor auxiliary module M2 moves away from the fixed contact W4, the control switch KA2 turns off, and the control switch KB2 of the thyristor auxiliary module M2 turns off. (8) When the movable contact J3 rotates to the center line position of the newly contacted fixed contact W1, the rotation stops, and one master switch switching is completed. The time interval t1 is greater than 0.015 seconds.

[0086] The switching control process for the tap changer in this embodiment when rotating counterclockwise under no-arc load conditions is as follows:

[0087] (1) The movable contact J3 begins to rotate counterclockwise from the center line position of the fixed contact W1 it is in contact with, the movable contact Q2 comes into contact with the fixed contact W2 connected to the fixed contact W1 that the movable contact J3 is in contact with, the movable contact Q1 comes into contact with the fixed contact W2 connected to the fixed contact W1 that the movable contact J3 is supposed to come into contact with, the control switch KA2 of the thyristor auxiliary module M2 comes into contact with the fixed contact W4, the control switch KA2 turns on, the load current flows through the movable contact J3 to the common terminal from the fixed contact W1 that the movable contact J3 is still in contact with, without any change in the flow path, (2) The movable contact J3 separates from the fixed contact W1 to which it was originally in contact, and the load current flows from the fixed contact W2 connected to the fixed contact W1 to the movable contact Q2, through the thyristor auxiliary module M2 to the common terminal. (3) The control switch KB2 of the thyristor auxiliary module M1 is turned on, and the load current flow path does not change. (4) The control switch KA2 of the thyristor auxiliary module M2 is released from the fixed contact W4, the control switch KA2 is turned off, and each zero-crossing point of the load current triggers the thyristor auxiliary module M1 once, causing the load current to flow from the fixed contact W2 connected to the fixed contact W1 to be contacted, through the movable contact Q1 and the thyristor auxiliary module M1 to the common terminal. (5) After the time interval t1 has elapsed, the control switch KA1 of the thyristor auxiliary module M1 contacts the fixed contact W3, the control switch KA1 turns on, and the load current flow path does not change. (6) The movable contact J3 contacts the fixed contact W1 that it is to contact, and the load current flows from the fixed contact W1 that the movable contact J3 contacts through the movable contact J3 to the common terminal. (7) When the movable contacts Q1 and Q2 no longer make contact with the fixed contact W2, the control switch KA1 of the thyristor auxiliary module M1 moves away from the fixed contact W3, the control switch KA1 turns off, and the control switch KB1 of the thyristor auxiliary module M1 turns off. (8) When the movable contact J3 rotates to the center line position of the newly contacted fixed contact W1, the rotation stops, and one master switch switching is completed.

[0088] The arc-free tap changer of this embodiment uses a rotating shaft as the driving power source, similar to conventional oil-filled tap changers, and can operate various switches and contacts within the oil tank of an oil-filled transformer. Therefore, the arc-free tap changer according to the present invention can be modified based on the basic structure of a conventional oil-filled tap changer.

[0089] Conventional oil-filled on-load tap changers are driven by AC motors. To prevent the switching process from being interrupted by power loss, conventional on-load tap changers are equipped with a spring energy release mechanism. If power is lost during the switching process, the spring energy release mechanism can ensure one complete switching process of the on-load tap changer. However, because the spring energy storage time is long and spring energy storage only occurs after receiving a switching command, one complete switching process of a conventional on-load tap changer is lengthy. The spring energy storage and spring energy release mechanisms of on-load tap changers have a complex structure, exhibit significant operating vibrations, and have a high failure rate.

[0090] Since the tap changer for non-arc load operation in this embodiment can employ DC motor drive and electrical energy storage, the spring energy storage mechanism and spring energy release mechanism may be omitted.

[0091] One point to note here is that the drive motor for the oil-filled on-load tap changer in this embodiment may be a DC motor. The AC power supply that would normally power the AC motor is now supplied to the DC motor through a bridge rectifier circuit and a voltage stabilization circuit. A capacitor energy storage circuit is connected in parallel to the output of the bridge rectifier circuit, and the electrical energy stored in the capacitor energy storage circuit is sufficient for the on-load tap changer to complete at least one complete operation. Since electrical energy storage can be performed before receiving a switching command, the time it takes for the arc-free on-load tap changer in this embodiment to complete one complete switching process is actually shortened. Thus, the spring energy storage mechanism and spring energy release mechanism may be omitted in the arc-free on-load tap changer in this embodiment.

[0092] In the arc-free load tap changer of this embodiment, the transition resistor is eliminated, and no heat-generating components are involved in the switch switching process. Thus, the switching process does not require a high-speed mechanism (which ensures that the energizing time of the transition resistor does not exceed 40 milliseconds) that is essential in conventional load tap changers. The switching process of the arc-free load tap changer of this embodiment may be completed in tens of seconds. Therefore, the arc-free load tap changer according to the present invention can be modified based on the basic structure of a conventional oil-immersed non-excited tap changer.

[0093] The arc-free tap changer in this embodiment has a simple structure, low operating vibration, and a low failure rate. The arc-free tap changer in the structure of Figure 2 is a composite arc-free tap changer. In a composite arc-free tap changer, the selector and the switching device are integrated, simplifying the structure of the on-load tap changer and reducing costs; however, it can only be applied when the selector is simple. If the selector of the on-load tap changer is complex and not suitable for a composite on-load tap changer, a combination structure in which the selector and the switching device are connected in series may be adopted. If the fixed contacts of the first rail in the structure of Figure 2 are reduced to two, it actually becomes the structure of a switching device. By connecting a switching device of such a structure in series with a conventional selector, a combination type arc-free tap changer can be constructed. [Examples]

[0094] This embodiment provides an arc-free load tap changer with the same structure as Embodiment 1. This embodiment differs from Embodiment 1 in that it controls control switches KB1 and KB2 by a mechanical interlocking mechanism.

[0095] As shown in Figure 5, the mechanical interlocking mechanism of this embodiment includes a deflection shaft 6, which is fixed to and rotates with the rotation shaft 4. A lever arm 7 and a spring arm 8 are attached to the deflection shaft 6, which are rotatable around the deflection shaft 6. One end of the spring arm 8 has a contact, which rotates with the rotation shaft 4 and makes contact with or disengages from a corresponding control switch, thereby opening and closing the corresponding control switch.

[0096] The operating process of the mechanical interlocking mechanism in this embodiment is as follows.

[0097] The rotating shaft 4 can drive and rotate the fixed plate 5, which is further equipped with a deflection shaft 6, to which a lever arm 7 and a spring arm 8 are attached. The lever arm 7 and the spring arm 8 are rotatable around the deflection shaft 6, and one end of the spring arm 8 has a contact. The stationary insulating frame has a hoop with the rotating shaft 4 as its center, and the hoop has gaps at the centerlines of the fixed contacts W1, and the hoop is divided into multiple segments, the number of gaps in the hoop being the same as the number of fixed contacts W1, for example, if there are three fixed contacts W1, there are three hoop gaps, and the three hoop gaps divide the hoop into a first hoop 9 and a second hoop 10. The normal operating state of the first arc-free load tap changer before switching is that the lever arm 7 is at the centerline of the hoop gaps.

[0098] When the rotation axis 4 is rotating clockwise, the lever arm 7 encounters the second hoop 10, which propels the lever arm 7 to rotate counterclockwise around the deflection axis 6. The lever arm 7 drives the spring arm 8 to rotate counterclockwise, causing the contacts of the spring arm 8 to contact the contacts of switch KB2, and switch KB2 turns on. When the lever arm 7 moves away from the second hoop 10 and encounters the next hoop gap, the lever arm 7 returns to the centerline of the hoop gap, and the spring arm 8 also returns to the centerline of the hoop gap. The contacts of the spring arm 8 move away from the contacts of switch KB2, and switch KB2 turns off.

[0099] When the rotation axis 4 is rotating counterclockwise, the lever arm 7 encounters the first hoop 9, which propels the lever arm 7 to rotate clockwise around the deflection axis 6. The lever arm 7 drives the spring arm 8 to rotate clockwise, causing the contacts of the spring arm 8 to contact the contacts of switch KB1, and switch KB1 turns on. When the lever arm 7 moves away from the first hoop 9 and encounters the next hoop gap, the lever arm 7 returns to the centerline of the hoop gap, and the spring arm 8 also returns to the centerline of the hoop gap. The contacts of the spring arm 8 move away from the contacts of switch KB1, and switch KB1 turns off.

[0100] Those skilled in the art will understand that the structure of a mechanical interlocking mechanism can be specifically designed according to the actual situation, and therefore a detailed explanation will be omitted here.

[0101] The main point to explain is that the switching control process for the tap changer under arc-free load conditions in this embodiment is the same as the switching control process for the tap changer under arc-free load conditions in Embodiment 1, and therefore a detailed explanation will be omitted here. [Examples]

[0102] This embodiment provides an arc-free load tap changer with the same structure as Embodiment 1. This embodiment differs from Embodiment 1 in that the control mechanism for controlling the control switches KB1 and KB2 is implemented by a changeover switch driven by a rotating shaft.

[0103] According to pages 63-66 of "Electrical Mechanism of On-Load Tap Changers," edited by Zhu Yinghao et al. and published in 2012 by Chugoku Electric Power Press, the changeover switch MTF driven by a rotating shaft can constitute control switches KB1 and KB2. In this book, the four fixed contacts of the changeover switch MTF are MTF1, MTF2, MTF3, and MTF4, and the changeover switch can switch between two states: (1) the first and third contacts are conductive and the second and fourth contacts are disconnected, and (2) the first and third contacts are disconnected and the second and fourth contacts are conductive. Contacts MTF1 and MTF3 can be at both ends of control switch KB1, and contacts MTF2 and MTF4 can be at both ends of control switch KB2.

[0104] One point to note is that the changeover switch MTF described in "The Electrical Mechanism of On-Load Tap Changers" is a high-current switch, while the control switches KB1 and KB2 are low-current switches. Therefore, it is necessary to reduce the size of the changeover switch MTF in accordance with its operating principle, while still achieving the functionality of the control switches KB1 and KB2. A detailed analysis is omitted.

[0105] The main point to explain is that the switching control process for the tap changer under arc-free load conditions in this embodiment is the same as the switching control process for the tap changer under arc-free load conditions in Embodiment 1, and therefore a detailed explanation will be omitted here. [Examples]

[0106] In the tap changer for use under no-arc load conditions shown in Figure 2, the radius of the fixed contact is large, while the radius of the movable contact is small. As can be seen from this, the radius of the contacts is used to control the length of the contact time and the contact sequence between the fixed and movable contacts.

[0107] This embodiment differs from Embodiment 1 in that, as shown in Figure 6, the radii of the fixed contacts are smaller and the radii of the movable contacts are larger.

[0108] The structure of the rotating shaft of the tap changer for non-arc load operation in this embodiment is shown in Figure 6. In this embodiment, the first rail has three fixed contacts arranged sequentially, and the radian of the distance between the center positions of the first and second fixed contacts on the first rail is equal to W, and the radian of the distance between the center positions of the second and third fixed contacts on the first rail is also equal to W. The second rail also has fixed contacts, and the number of fixed contacts on the second rail is equal to the number of fixed contacts on the first rail. The center line of each fixed contact on the first rail coincides with the center line of one fixed contact on the second rail, and the fixed contacts on the first rail and the fixed contacts on the second rail whose center lines coincide are connected, and are also sequentially connected to the three taps of the transformer coil L1.

[0109] The rotating shaft of this embodiment has at least three movable contacts, namely movable contact J3, movable contact Q1, and movable contact Q2. The movable contacts are attached to the rotating shaft and rotate together with the rotating shaft. While the movable contact J3 rotates together with the rotating shaft, it is sequentially connected to three fixed contacts on the first rail. While the movable contacts Q1 and Q2 rotate together with the rotating shaft, they are sequentially connected to three fixed contacts on the second rail. The center position of the movable contact Q1 is on the second rail to the left of the center position of the movable contact J3, and the included angle between the two is 0.5W. The center position of the movable contact Q2 is on the second rail to the right of the center position of the movable contact J3, and the included angle between the two is 0.5W.

[0110] The radian of the contact of the movable contact J3 is W 1可動 and the radians of the contacts of the movable contacts Q1 and Q2 are W 2可動 and the radian of the gap between the movable contact Q1 and the movable contact Q2 is ΔW 可動 =(W - W 2可動 ) is. As shown in Figure 6, 0 < ΔW < W 1可動 <0.5W < W 2可動 is required. Here, W is the radian between the center positions of each fixed contact on the first rail.

[0111] [[ID=!20]]What needs to be further explained here is that the opening and closing of the control switch in this embodiment are controlled by a control mechanism. Here, the control mechanism may be realized by the control mechanism of Embodiment 2 or Embodiment 3 or other conventional control mechanisms. Those skilled in the art can specifically select according to the actual situation, and the detailed description is omitted here.

[0112] The switching control method of the tap changer under no-arcing load in this embodiment is the same as the switching control method of the tap changer under no-arcing load in Embodiment 1, and the detailed description is omitted here. The content about the tap changer under no-arcing load in this embodiment is the same as that of the tap changer under no-arcing load in Embodiment 1, and the detailed description is omitted.

[0113] It should be noted that in the translation of the original text, there may be some inaccuracies in the understanding of the technical content. It is recommended to combine the actual technical background for a more accurate understanding. And for the part of "[[ID=!20]]", there may be an error in the original text tag. It is guessed that it should be "". If there are other specific requirements or corrections, please feel free to let me know.Comparing Figure 2 and Figure 6, the arc of each fixed contact on the first and second rails of the arc-free load tap changer in this embodiment is small, the arc of the movable contact is large, and there are only three movable contacts, and there may be a large number of fixed contacts. Therefore, the manufacturing cost of the arc-free load tap changer in this embodiment is lower than that of the arc-free load tap changer in Embodiment 1. [Examples]

[0114] This embodiment includes at least two master switches, two changeover switches, and two thyristor auxiliary modules, each thyristor auxiliary module including two control switches, and the two master switches including one originally on master switch and one to be turned on, the master switches being connected to corresponding circuits of voltage regulating coils via corresponding transformer taps, and the two thyristor auxiliary modules being connected in parallel to the originally on master switch or the master switch to be turned on, depending on the timing required during the switching process of the master switches. The master switch and the changeover switch are both rotary switches, and the master switch and the corresponding changeover switch rotate in conjunction and synchronously. By controlling the opening and closing of the corresponding master switch, changeover switch and control switch according to predetermined timings, a seamless transfer of load current from the originally ON master switch to the master switch to be ON is achieved, and no electric arc is generated during the opening and closing process of each switch, providing an arc-free load tap changer.

[0115] What needs to be explained here is that the control mechanism is a mechanical interlocking mechanism, and its structure may be the specific structure of the mechanical interlocking mechanism described in Example 2, or the control mechanism described in Example 3, and a person skilled in the art can specifically set it according to the actual situation. A detailed explanation is omitted here.

[0116] In this embodiment, the structures of the two thyristor auxiliary modules are the same, and their specific structures are shown in Figure 1. The specific explanation is the same as in Embodiment 1, so a detailed explanation is omitted here.

[0117] The switching control method for the tap changer under arc-free load conditions in this embodiment is: The steps include controlling the opening and closing of the corresponding master switch and changeover switch so that they rotate in conjunction and in sync, The method includes a step of controlling the opening and closing of the corresponding master switch, changeover switch, and control switch according to a predetermined timing, thereby achieving a seamless transfer of load current from the master switch that was originally on to the master switch that should be turned on, and ensuring that no electric arcs are generated during the opening and closing process of each switch.

[0118] <Electrical Equipment> In one or more embodiments, A voltage regulating coil including multiple transformer taps, The system includes a tap changer for use with no electric loads connected to the voltage adjustment coil, The present invention provides an electrical device in which the arc-free load tap changer is the arc-free load tap changer described in any of the above embodiments 1 to 5.

[0119] The transformer in this embodiment is an oil-filled transformer or a transformer equipped with an oil-filled vacuum-load tap changer.

[0120] The electrical equipment can be configured in any way and manner according to the needs, for example, as a compensating choke coil to affect reactive power in an alternating power grid, or as a local power grid transformer or power transformer or variable transformer or phase shift transformer or rectifier transformer or reactive power compensator, and / or the equipment may or may not include at least one additional regulating winding, and / or may or may not include at least one additional arc-free load tap changer, and / or may include at least one main winding.

[0121] By using each of the proposed on-load tap changers and each of the proposed devices, for example, one of the proposed methods can be implemented.

[0122] Preferably, each of the proposed arc-free on-load tap changers is configured and / or used and / or applied to implement and / or perform one of the proposed methods. Preferably, each of the proposed devices is configured and / or used and / or applied to implement and / or perform one of the proposed methods.

[0123] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will know that the present invention can be modified and altered in various ways. Any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and principles of the invention shall be within the scope of protection of the present invention. [Explanation of symbols]

[0124] 1 Tap I 2 Tap II 3 Tap III 4 rotation axes 5 Fixed plate 6 Deflection axis 7 Lever Arm 8 Spring Arms 9. First hoop 10. Second hoop 11 Switch KB1 12 Switch KB2

Claims

1. An arc-free load tap changer comprising at least one master switch, a first changeover switch, a second changeover switch, a first thyristor auxiliary module (M1), and a second thyristor auxiliary module (M2), wherein the first thyristor auxiliary module (M1) comprises two control switches (KA1, KB1), the second thyristor auxiliary module (M2) comprises two control switches (KA2, KB2), either the first thyristor auxiliary module (M1) or the second thyristor auxiliary module (M2) comprises a pair of thyristors (D1, D2) connected in parallel in opposite directions, and three first fixed contacts (131, 132, 133) are connected to corresponding taps on the voltage regulating coil of a transformer (L1). The master switch, the first changeover switch, and the second changeover switch are all rotary switches, and are mounted on the rotating shaft (4). The master switch includes a third movable contact (J3), the first changeover switch includes a first movable contact (Q1), and the second changeover switch includes a second movable contact (Q2). The switch-on position of the master switch is the position in which the third movable contact (J3) contacts the first fixed contacts (131, 132, 133), and the three second fixed contacts (141, 142, 143) that can contact the first movable contact (Q1) and the second movable contact (Q2) are connected to the first fixed contacts (131, 132, 133) and further connected to the corresponding taps of the transformer (L1). During the clockwise or counterclockwise rotation process of the rotating shaft (4), the third movable contact (J3) can come into contact with or separate from the first fixed contacts (131, 132, 133) according to a predetermined switch timing, and the first movable contact (Q1) and the second movable contact (Q2) can come into contact with or separate from the second fixed contacts (141, 142, 143) according to the predetermined switch timing. The first movable contact (Q1) and the second movable contact (Q2) are arranged on both sides of the third movable contact (J3), respectively, with the center position of the first movable contact (Q1) being to the left of the center position of the third movable contact (J3) and the angle between them being 0.5W, and the center position of the second movable contact (Q2) being to the right of the center position of the third movable contact (J3) and the angle between them being 0.5W, where W is the angle between the center positions of two adjacent first fixed contacts (131 and 132, or 132 and 133). The first thyristor auxiliary module (M1) and the second thyristor auxiliary module (M2) are configured to have the same structure, the third movable contact (J3) is connected to a common terminal, both ends of the main circuit of the first thyristor auxiliary module (M1) are connected to the first movable contact (Q1) and the common terminal, and both ends of the main circuit of the second thyristor auxiliary module (M2) are connected to the second movable contact (Q2) and the common terminal, The control switches (KA1, KB1, KA2, KB2) are arranged on the rotating shaft (4) as switches that rotate together with the rotating shaft (4), and when the rotating shaft (4) encounters fixed contacts (W3, W4) and circular hoops (9, 10) during the rotation process, the opening and closing of the control switches (KA1, KB1, KA2, KB2) is activated, in an arc-free load tap changer.

2. The first fixed contacts (131, 132, 133) are fixedly mounted on a first arc-shaped track centered on the rotation axis (4), and the angle between the center positions of two adjacent fixed contacts (131 and 132, or 132 and 133) is equal. The second fixed contacts (141, 142, 143) are fixedly mounted on a second arc-shaped track centered on the rotation axis (4), and the angle between the center positions of two adjacent fixed contacts (141 and 142, or 142 and 143) is equal. The first fixed contacts (131, 132, 133) correspond to the second fixed contacts (141, 142, 143) in pairs, and their center positions coincide in each pair. The relationship of the radians for all fixed contacts (131, 132, 133, 141, 142, 143) is: 0<ΔW<W1<0.5W<W2 ΔW = (W - W²) The tap changer for non-radial load operation according to claim 1, wherein W1 is the radian of the first fixed contacts (131, 132, 133), W2 is the radian of the second fixed contacts (141, 142, 143), W is the radian between the center positions of two adjacent first fixed contacts, and ΔW is the radian between the center positions of two adjacent second fixed contacts.

3. Before switching the master switch, the normal operating state of the arc-free load tap changer is: The arc-free load tap changer according to claim 1, characterized in that the third movable contact (J3) is at the center position of the first fixed contact (132), and the first movable contact (Q1) and the second movable contact (Q2) are each at the center position of the gap between two adjacent second fixed contacts (141 and 142, 142 and 143).

4. During the rotation process of the rotating shaft (4), The opening and closing of the first control switch (KA1) of the first thyristor auxiliary module (M1) is triggered when the movable contact of the first control switch (KA1) of the first thyristor auxiliary module (M1) passes through a plurality of arc-shaped sections of the third fixed contact (W3). The opening and closing of the first control switch (KA2) of the second thyristor auxiliary module (M2) is triggered when the movable contact of the first control switch (KA2) of the second thyristor auxiliary module (M2) passes through a plurality of arc-shaped sections of the fourth fixed contact (W4). The opening and closing of the second control switch (KB1) of the first thyristor auxiliary module (M1) is triggered when the spring arm (8) of the fourth movable contact makes contact with or separates from the switch KB1 (11), which is the first trigger contact. The tap changer for non-arc load operation according to claim 1, characterized in that the opening and closing of the second control switch (KB2) of the second thyristor auxiliary module (M2) is triggered by the spring arm (8) of the fourth movable contact contacting or separating from the switch KB2 (12), which is the second trigger contact.

5. The opening and closing of the aforementioned control switch is controlled by a control mechanism. The control mechanism is a mechanical interlocking mechanism, The mechanical interlocking mechanism includes a deflection shaft (6), which is fixed to the rotation shaft (4) and rotates together with the rotation shaft (4). A lever arm (7) and a spring arm (8) are attached to the deflection shaft, which are rotatable around the deflection shaft (6). One end of the spring arm (8) has a contact, which rotates together with the rotation shaft (4) to contact or disengage from the corresponding control switch, thereby opening and closing the corresponding control switch. The tap changer for non-arc load operation according to claim 1, characterized in that the control mechanism is realized by a changeover switch driven by the rotating shaft (4).

6. An RC series circuit is connected in parallel to both ends of the thyristors (D1, D2) which are connected in parallel in opposite directions. Between the gate and cathode of each of the aforementioned thyristors (D1, D2), capacitors (C3, C4), resistors (R3, R4), and diodes (D3, D4) are connected in order. The positive terminals of the diodes (D3, D4) are connected to the cathodes of the corresponding thyristors (D1, D2), and the negative terminals of the diodes (D3, D4) are connected to the gates of the corresponding thyristors (D1, D2). Between the gates of the two thyristors (D1, D2) connected in parallel in opposite directions, one of the two control switches (KB) is further connected in series via a full-bridge rectifier circuit, and between the gates of the two thyristors (D1, D2) connected in parallel in opposite directions and the other control switch (KA), a first Zener diode (D10), a second Zener diode (D11), and a resistor (R5) are further connected in series, and the first Zener diode (D10) and the second Zener diode (D11) are connected in series in opposite directions. The third Zener diode (D9) and resistor (R6) are connected in series, and then connected to the output terminal of the full-bridge rectifier circuit. The arc-free load tap changer according to claim 1, characterized in that the negative terminal of the third Zener diode (D9) is connected to the positive output terminal of a full-bridge rectifier circuit, and the positive terminal of the third Zener diode (D9) is connected to the negative output terminal of a full-bridge rectifier circuit.

7. A method for controlling the switching of a tap changer under no-arc load conditions according to any one of claims 1 to 5, The steps include controlling the rotation of the rotating shaft (4), controlling the open / closed state of the master switch, the first and second changeover switches, and the corresponding control switches (KA1, KB1, KA2, KB2), and driving the movable contacts (J3, Q1, Q2) to connect to or disconnect from the corresponding fixed contacts (131, 132, 133, 141, 142, 143), A method for controlling the switching of an arc-free load tap changer, characterized by including a step in which, while the rotating shaft (4) is rotating, the load current is transferred without interruption from the current switch-on position of the master switch to the next switch-on position of the master switch, in accordance with the predetermined switch timing, and no electric arc is generated during the opening and closing process of each switch.

8. The rotation method of the aforementioned rotating shaft (4) includes clockwise rotation, The process of switching the master switch once is: When the aforementioned rotating shaft (4) begins to rotate clockwise, The third movable contact (J3) begins to move from the center position of the first fixed contact (131 or 132) in which the third movable contact (J3) is in contact, the first movable contact (Q1) comes into contact with the second fixed contact (141 or 142) connected in correspondence with the first fixed contact (131 or 132) in which the third movable contact (J3) is in contact, and the second movable contact (Q2) comes into contact with the second fixed contact (142 or 143) connected in correspondence with the first fixed contact (132 or 133) in which the third movable contact (J3) is in contact, This turns on the first control switch (KA1) of the first thyristor auxiliary module (M1) connected between the master switch and the first changeover switch. Subsequently, the third movable contact (J3) separates from the first fixed contact (131 or 132), turning on the second control switch (KB2) of the second thyristor auxiliary module (M2) connected between the master switch and the second changeover switch, while simultaneously turning off the first control switch (KA1) of the first thyristor auxiliary module (M1). When the set time interval (t1) has elapsed, the first control switch (KA2) of the second thyristor auxiliary module (M2) is turned on, and the third movable contact (J3) moves to and makes contact with the first fixed contact (132 or 133) located in the next switch-on position. Subsequently, the first and second movable contacts (Q1, Q2) disengage from the second fixed contacts (141 and 142, or 142 and 143), turning off the first control switch (KA2) of the second thyristor auxiliary module (M2), and turning off the second control switch (KB2) of the second thyristor auxiliary module (M2). The rotation of the rotating shaft (4) stops when the third movable contact (J3) approaches the center position of the first fixed contact (132 or 133) that it will next contact, thereby completing one switching of the master switch. Alternatively, the switching control method for an arc-free load tap changer according to claim 6, characterized in that the voltage across the first and second thyristor auxiliary modules (M1, M2) is set to zero before switching the master switch.

9. The rotation method of the rotating shaft (4) includes counterclockwise rotation, The process of switching the master switch once is as follows: When the aforementioned rotating shaft (4) begins to rotate counterclockwise, The third movable contact (J3) begins to move from the center position of the first fixed contact (133 or 132) with which the third movable contact (J3) is in contact, the second movable contact (Q2) comes into contact with the second fixed contact (143 or 142) connected in correspondence with the first fixed contact (133 or 132) with which the third movable contact (J3) is in contact, and the first movable contact (Q1) comes into contact with the second fixed contact (142 or 141) connected in correspondence with the first fixed contact (132 or 131) with which the third movable contact (J3) is in contact. This turns on the first control switch (KA2) of the second thyristor auxiliary module (M2) connected between the master switch and the second changeover switch. Subsequently, the third movable contact (J3) separates from the first fixed contact (133 or 132), turning on the second control switch (KB1) of the first thyristor auxiliary module (M1) connected between the master switch and the first changeover switch, while simultaneously turning off the first control switch (KA2) of the second thyristor auxiliary module (M2). When the set time interval (t1) has elapsed, the first control switch (KA1) of the first thyristor auxiliary module (M1) is turned on, and the third movable contact (J3) moves to and makes contact with the first fixed contact (132 or 131) located in the next switch-on position. Subsequently, the second and first movable contacts (Q2, Q1) disengage from the second fixed contacts (143 and 142, or 142 and 141), turning off the first control switch (KA1) of the first thyristor auxiliary module (M1), and turning off the second control switch (KB1) of the first thyristor auxiliary module (M1). The rotation of the rotating shaft (4) stops when the third movable contact (J3) approaches the center position of the first fixed contact (132 or 131) that it will next contact, thereby completing one switching of the master switch. Alternatively, the switching control method for an arc-free load tap changer according to claim 6, characterized in that the voltage across the first and second thyristor auxiliary modules (M1, M2) is set to zero before switching the master switch.

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