CN104157491A - Transformer integrated arc-free load-equipped tap switch - Google Patents

Abstract

The invention discloses a transformer integrated arc-free load-equipped tap switch. The transformer integrated arc-free load-equipped tap switch comprises a fixed contact connected with a transformer tapping, a moving contact D1 connected with a transformer outlet terminal and driven by a motor, and a controlling circuit, wherein the moving contact D1 comprises a first bilateral switch branch of which one end is connected with the outlet terminal, a direct connection contact terminal and a second bilateral switch branch; both of the first switch branch and the second bilateral switch branch are formed by adopting the structure that two power electronic switches are connected in a combined manner, then, a cushion circuits is connected with the two power electronic switches in parallel, and a fuse is connected in series. The bilateral switches and sequential control on triggering of the bilateral switches are adopted to realize arc-free switching of load-equipped tap switches, an accident during failure of the bilateral switches is prevented, reliable power supply is ensured for the controlling circuit, and the transformer integrated arc-free load-equipped tap switch is simple in structure and reliable in working.

Description

A transformer-integrated arc-free on-load tap-changer

technical field

The invention relates to the technical field of transformer voltage regulation, and more specifically relates to a transformer integrated arc-free on-load tap changer.

Background technique

In the prior art, for a distribution transformer in operation, due to changes in the primary side voltage, load size and nature, the secondary side voltage may have a large change. my country's distribution transformers cover a voltage level below 35kV. In order to maintain the load voltage within the specified range and ensure the normal needs of electrical equipment, the distribution transformer must be adjusted.

The basic principle of transformer on-load voltage regulation is to draw several taps from the coil on one side of the transformer, generally the high-voltage side, and switch from one tap to the other through the on-load tap changer without cutting off the load current. A tap to change the number of effective turns to adjust the voltage. The on-load tap changer is composed of two parts, one part is the transformer body, which is different from the usual transformer in that it leads to multiple taps, and the other part is the on-load tap changer, which can be supplied and assembled by different manufacturers.

Commonly used transformer on-load tap-changers are divided into two categories: mechanical type and vacuum type. Mechanical on-load tap-changers have two structures: one-piece and two-piece.

In the integrated mechanical on-load tap-changer, the winding taps directly form a circular body, and each tap constitutes a static contact. The moving contact is composed of a contact with transition resistance and a straight contact, which can be in the form of single transition resistance, double transition resistance or multiple transition resistance.

Split mechanical on-load tap-changers consist of a switch selector and a diverter switch. The switch selector is composed of two rings, which are respectively connected to the odd-numbered and even-numbered taps. The tap selector drives the motor to drive the moving contacts of the tap selector to connect to one tap respectively. The two moving contacts of the tap selector output as The two static contacts of the diverter switch, each static contact is equipped with a transition resistor to form a double resistance structure, and only one contact is connected to the output cable in a steady state. The moving contact of the diverter switch has only one straight-through contact, which is driven by the diverter switch drive motor to switch from one static contact to the other.

Vacuum tap changers generally adopt a split structure, and the taps of the windings are switched by the tap selector. The static contacts of the diverter switch are respectively connected to a vacuum switch, a transitional vacuum switch is installed between the two static contacts, and a transitional resistor is installed between the transitional vacuum switch and one of the static contacts. Three vacuum switch outputs have two structures: fixed connection and mobile connection. In the fixed connection mode, the output of the three vacuum switches can be short-circuited and fixedly connected to the winding, and the current can be transferred between different taps only by controlling the vacuum switch. The mobile connection method adopts a moving contact, and the moving contact has only one straight-through contact, which is driven by the switching switch to switch from one static contact to the other. During the movement, the position of the moving contact is judged in real time to realize the vacuum switch The on-off control of the transformer ensures that the transformer winding is not open circuited and the winding taps are not short-circuited.

The problems existing in the existing technology are: the mechanical tap changer generates an arc during the tap switching process, causing contact ablation; when the vacuum tap changer adopts a fixed structure, the off-state vacuum switch is always under voltage, and it needs to be designed according to the system voltage. When the mobile structure is adopted, due to the slow opening and closing time of the vacuum switch, the moving speed of the moving contact needs to be coordinated with it, which is difficult to control; and the above-mentioned tap changer needs transition resistance, which increases the loss.

At present, there is an all-electronic tap changer structure. The electronic switch is composed of power electronic devices such as thyristors. Each transformer winding tap is connected to an electronic switch. The tap switching is realized through certain timing control and does not require transition resistors. This solution requires high withstand voltage of the electronic switch, and the structure is complex and expensive.

There is also an electromechanical hybrid tap changer structure, which is equivalent to replacing the double transition resistors of the mechanical tap changer with anti-parallel thyristors, and the tap switching is realized by controlling the opening and closing of the thyristors and the moving position of the straight-through contacts. In this scheme, since the thyristor is a semi-controlled device, it is difficult to realize the timing coordination of the thyristor on and off when the movable contact moves.

In addition, there is another electromechanical hybrid tap-changer mechanism, which is equivalent to replacing the double transition resistance of the mechanical tap-changer with two anti-series power electronic switches. The moving position of the head cooperates to realize tap switching. In this scheme, the power electronic switch adopts fully controlled devices such as IGBT or MOSFET.

During the switching process of the above two electromechanical hybrid structures, if the power electronic switch fails, the winding will be short-circuited when it is in a short-circuit state after the fault. The full voltage of the pressure-side coil is applied to both ends of the power electronic switch, which breaks down and burns the control part.

For this kind of fault, there is another structure that connects transition resistors in parallel at both ends of the power electronic switch on this basis. When the power electronic switch fails and the result is an open circuit, it can still be used as a conventional on-load tap changer. This solution still has an arcing process during the switching process, and cannot realize the arc-free operation of the on-load tap-changer.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present invention is how to realize the arc-free switching process of the transformer on load, and at the same time stop the switching process in time without damaging the device when a short circuit or an open circuit occurs during the switching process.

(2) Technical solutions

In order to solve the above technical problems, the present invention provides a transformer-integrated arc-free on-load tap-changer, which includes a static contact connected to the transformer tap, and a motor-driven moving contact connected to the transformer outlet terminal, which also includes Control loop;

The moving contact includes a first two-way switch branch connected to an outlet terminal at one end, a straight-through contact, and a second two-way switch branch; both the first switch branch and the second two-way switch branch are composed of two power electronics After the switch combination is connected, a buffer circuit is connected in parallel, and then connected in series with a fuse;

The control loop includes a trigger unit and a detection unit; the detection unit detects the current flowing through the outlet terminal, the current of the through contact, the current of the first bidirectional switch branch and the second bidirectional switch branch and the pressure drop and the pressure drop of two adjacent static contacts, and after calculating the obtained data, send a control command to the trigger unit, and the trigger unit is the first bidirectional switch branch, the second bidirectional switch branch, and the second bidirectional switch branch. The power electronic switch of the switching branch provides the trigger signal.

Preferably, a buffer circuit is connected in parallel between the first switch branch and the second bidirectional switch branch.

Preferably, the buffer circuit is a capacitor or a resistance-capacitance circuit.

Preferably, during the movement of the movable contact, the first bidirectional switch branch, the through contact, and the second bidirectional switch branch are sequentially connected to each of the static contacts.

Preferably, the device further includes a control power supply unit, the control power supply unit uses the voltage drop of the two adjacent fixed contacts as the input stage voltage, and supplies power to the control loop.

Preferably, another set of static contacts connected to the taps of the transformer is also included, and the voltage drop between two adjacent contacts of the other set of static contacts supplies power to the control power supply unit.

Preferably, the control loop further includes a communication unit and a motor drive unit, the communication unit uploads the data detected by the detection unit to the upper computer, and the upper computer controls the drive motor unit to drive the movable contact action.

Preferably, the control power supply unit converts the input stage voltage into a DC voltage through its internal isolation and conversion circuit, supplies power to the control circuit through the discharge module, and charges its internal charging module at the same time; the control power supply unit When the input stage voltage is zero, the charging module supplies power to the control loop through the discharging module.

Preferably, the power electronic switch adopts a half-controlled device of a thyristor or a fully-controlled device of an IGBT or a MOSFET.

Preferably, when the power electronic switch adopts a semi-controlled device of a thyristor, the combined connection form of the two power electronic switches is an anti-parallel connection; The combined connection form is anti-serial connection.

(3) Beneficial effects

The invention provides a transformer-integrated arc-free on-load tap-changer. The invention realizes the arc-free switching of the on-load tap-changer by using a bidirectional switch and the trigger sequence control of the bidirectional switch, and prevents the bidirectional switch from malfunctioning. When the accident is expanded, the reliable power supply of the control circuit is guaranteed, and the structure is simple and the work is reliable.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a circuit diagram of a transformer-integrated arc-free on-load tap-changer according to a preferred embodiment of the present invention;

Fig. 2 is a structural schematic diagram of a control circuit of a transformer-integrated arc-free on-load tap-changer according to a preferred embodiment of the present invention;

Fig. 3 is a structural schematic diagram of a control power supply unit of a transformer-integrated arc-free on-load tap-changer according to a preferred embodiment of the present invention;

Figures 4a-4e are state diagrams of the process of switching from R1A to R2A for the moving contact D1 of a diverter switch of a transformer-integrated arcless on-load tap-changer according to a preferred embodiment of the present invention;

Figures 5a-5c are state diagrams of another set of static contacts of a transformer-integrated arc-free on-load tap-changer in a preferred embodiment of the present invention supplying power to the control power supply unit;

Figs. 6a-6d are diagrams of electronic switch timing control state diagrams of a transformer-integrated arcless on-load tap-changer according to a preferred embodiment of the present invention.

Fig. 7 is a perspective view of a transformer-integrated arcless on-load tap changer according to a preferred embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but should not be used to limit the scope of the present invention.

Figure 1 is a circuit diagram of a transformer-integrated arc-free on-load tap-changer according to a preferred embodiment of the present invention; the switch includes a static contact connected to a transformer tap, a motor-driven The moving contact D1 also includes a control circuit. The moving contact D1 includes a first two-way switch branch connected to an outlet terminal at one end, a straight-through contact, and a second two-way switch branch; both the first switch branch and the second two-way switch branch are controlled by two power After the electronic switch combination is connected, a buffer circuit is connected in parallel, and then connected in series with a fuse. A buffer circuit C3 is connected in parallel between the first switch branch and the second bidirectional switch branch.

In Figure 1, L and N respectively represent the incoming and outgoing terminals of the transformer winding; in this embodiment, the power electronic switch adopts an insulated gate bipolar transistor, the English full name is Insulated Gate Bipolar Transistor, and the English abbreviation is IGBT, which is composed of two IGBTs in anti-series connection Two-way switch, two ends of each two-way switch are connected in parallel with a buffer circuit, and then connected in series with a fuse to form a two-way switch branch, that is, the first one-way switch S11, the second one-way switch S12, the buffer circuit C1 and the fuse M1 constitute the first A bidirectional switch branch S1, while the third unidirectional switch S21, the fourth unidirectional switch S22, the snubber circuit C2 and the fuse M2 form a second bidirectional switch branch S2. The function of the buffer circuit is: when the bidirectional switch is turned off, the inductance part in the current loop will form an overvoltage, and the buffer circuit will protect the bidirectional switch branch at this time. The function of the fuse is: when the fault result of the bidirectional switch branch is a short circuit, if the switch is continued, the fuse will be blown to avoid the short circuit of the winding. operate. When the bidirectional switch branch fault results in an open circuit, it will cause an open circuit of the load, which can be identified after calculation by the detection unit in the control loop, and further operation is prohibited. Taking the process in Figure 4 as an example, if S21 has an open circuit fault, in the 4c state, after S21 is applied with a trigger signal, since S21 is already open, the second bidirectional switch branch S2 is still disconnected, and the switching continues , the first bidirectional switch S1 will be turned off, which will cause the load to open circuit, and uS2 will increase instantaneously at both ends of S2, forming an overvoltage as a fault identification signal; At this time, the stage voltage passes through the static contact R1A, the direct contact K, the second bidirectional switch branch S2 and the static contact R2A form a path, at this time, the winding is equivalent to a short circuit, and the current iK of the direct contact K increases instantaneously , forming an overcurrent as a fault identification signal, and the rest of the fault identification signals are similar to this.

The power electronic switch can withstand high voltage in the forward direction and not withstand the voltage in the reverse direction, and a diode is connected in antiparallel with it to form a one-way switch, and two one-way switches are connected in reverse series to form a two-way switch. Taking the first bidirectional switch branch S1 composed of the first unidirectional switch S11 and the second unidirectional switch S12 as an example, when no trigger signal is applied, both unidirectional switches are in the off state, and the bidirectional switch branch is in the Off state: when the first one-way switch S11 bears a positive voltage, a trigger signal is applied to the first one-way switch S11, and the one-way switch forms a path with the diode of the second one-way switch S12, that is, the first two-way switch branch S1 conduction; when the second one-way switch S12 bears a positive voltage, a trigger signal is applied to the second one-way switch S12, and the one-way switch forms a path with the diode of the first one-way switch S11, that is, the first two-way switch branch S1 conduction; if the unidirectional switch bearing the positive voltage does not apply a trigger signal, and applies a trigger signal to another unidirectional switch in anti-series, the bidirectional switch branch cannot be conducted; when the first unidirectional switch S11 and When the trigger signal is applied to the second unidirectional switch S12 at the same time, no matter what the voltage direction is, the bidirectional switch branch is in the on state.

The transformer integrated arc-free on-load tap changer described in this embodiment also includes a set of static contacts connected to the transformer taps, the other two moving contacts D2, D3 and a control power supply unit; the two sets of static contacts The contacts are group A static contacts and group B static contacts. The group A static contacts include R1A, R2A, R3A and other static contacts, and the B group static contacts include R1B, R2B, R3B and other static contacts. The moving contacts D2 and D3 are connected to two adjacent static contacts of the group B static contacts, and supply power to the control power supply unit at the same time. Group A static contacts R1A, R2A and other static contacts are sequentially connected with the first bidirectional switch branch S1, the through contact K and the second bidirectional switch branch S2 located on the movable contact along with the movement of the movable contact D1, During the moving process, the contacts D2 and D3 are sequentially connected with the static contacts of group B R1B, R2B, R3B and so on.

Fig. 2 is a structural diagram of a control circuit of a transformer integrated arc-free on-load tap-changer according to a preferred embodiment of the present invention. The control circuit includes a trigger unit and a detection unit; the detection unit detects the outgoing line The current i flowing through the terminal, the through contact current iK, the current and voltage drop iS1, iS2, uS1, uS2 of the first bidirectional switch branch and the second bidirectional switch branch, and the moving contact D2, D3 voltage drop U ₀ , and calculate the obtained data and issue a control instruction to the trigger unit, and the trigger unit provides trigger signals for the power electronic switches of the first bidirectional switch branch and the second bidirectional switch branch . The control loop also includes a power supply, a communication unit and a motor drive unit, and the power supply supplies power to each part of the control loop; the communication unit includes a first communication unit, a second communication unit, and a third communication unit; the first communication unit uses To communicate with the upper computer, upload the data detected by the detection unit, and receive the shift control command issued by the upper computer; the second communication unit is used for the third communication unit to upload the data detected by the detection unit; The contacts D1, D2, and D3 are controlled and moved to the target position; the trigger unit performs sequential control on the power electronic switch of the bidirectional switch branch according to the trigger signal sent by the detection unit, so as to realize arcless switching of the on-load tap changer. The detection unit detects the working state of the two-way switch branch, and when there is a fault, sends a fault signal to the host computer through the third communication unit, and stops the switching process.

Fig. 3 is a structural diagram of a control power supply unit of a transformer-integrated arc-free on-load tap-changer in a preferred embodiment of the present invention; the control power supply unit includes two states, when the second moving contact D2 and When the third movable contact D3 is in the first state, the input stage voltage is U ₀ , and the output terminal U _DC0 is a 24V DC voltage to supply power for the control loop. Control the isolation and conversion circuit inside the power supply unit to convert the stage voltage into direct current. Since the voltage value of the stage voltage varies from hundreds to thousands according to the different transformer models, considering the insulation requirements, the voltage conversion device can adopt industrial Frequency isolation or high frequency isolation power supply technology, high frequency isolation technology is smaller than power frequency isolation and easy to install. The converted DC current passes through the charging module to charge the energy storage medium and at the same time outputs 24V DC at the output terminal through the discharge module, wherein the energy storage medium can be a supercapacitor or a battery. When the moving contact D2 and moving contact D3 are in the second state during the switching process, that is, the input stage voltage of the control power supply module is zero, the energy storage medium is discharged, and 24V DC is output at the output terminal through the discharge module, ensuring the control circuit reliable power supply.

The following describes the switching process of the moving contact D1:

The moving contact D1 is switched from the static contact R1A of group A to R2A, while the moving contact D2 is switched from the static contact R1B of group B to R2B, and the moving contact D3 is switched from the static contact R2B of group B to R3B, or, group A The static contact R2A is switched to R1A, the moving contact D2 is switched from group B static contact R2B to R1B, and the moving contact D3 is switched from group B static contact R3B to R2B. In the steady state, the straight-through contact K of the moving contact D1 is connected to the static contact R1A of group A, and the load current passes through the winding inlet terminal L, the winding, and the static contact R1A of group A, and is connected to the outgoing line through the straight-through moving contact K Terminal N, thus forming a current path. The moving contact D2 is connected to the static contact R1B of the group B, and the moving contact D3 is connected to the static contact R2B of the group B to provide voltage for the input terminal of the control power supply unit. Assume at this time that an instruction from the host computer is received to switch the on-load tap-changer from group A static contact R1A to R2A, the moving process of the moving contact D1 is shown in Figure 4a-4e, the second moving contact D2 and the third moving contact The moving process of the head D3 is shown in Figures 5a-5c, where only the switching part is shown for simplicity.

When the through contact K moves from the fixed contact R1A to the position of the fixed contact R2A, the mechanical action is a continuous process, and the time taken is on the order of milliseconds. During this movement, the first one-way switch S11 and the second one-way switch S12 of the first two-way switch branch S1 and the third one-way switch S21 and the fourth one-way switch S22 of the second two-way switch branch S2 pass through With a certain sequence of timing, the arc-free switching from the static contact R1 to the static contact R2 is realized. The switching time of the electronic switch is on the order of microseconds, and the switching can be completed during the mechanical movement.

In the present invention, the electrical switching process must control the opening and closing of the bidirectional switch at different moving positions of the mechanical process, and the opening and closing process must be based on a certain sequence to avoid load open circuit or winding short circuit.

As shown in Figure 4a, here only two adjacent static contacts R1A and R2A are taken as an example, and the analysis of other switching processes is the same. The straight-through contact K is connected to one end of the static contact R1A, and the first bidirectional switch branch S1 and the second bidirectional switch branch S2 are not connected to the static contact R1A and the static contact R2A. At this time, all four power electronic switches are all turned off. The detection unit detects the direction of the current iK through the contact K, and detects the voltages uS1 and uS2 at both ends of the first bidirectional switch branch S1 and the second bidirectional switch branch S2 while moving, if it is detected that S2 bears the stage voltage U ₀ , the moving contact is switched from the static contact R1A to R2A, and then triggers the one-way switch according to the direction of iK, the detection unit detects the current iK through the contact K, when iK>0, triggers the first A one-way switch S11 makes the first two-way switch branch S1 conduction; when iK<0, triggers the second one-way switch S12 to make the first two-way switch branch S1 conduction; The contact R1A is connected, and since the direct contact K has a small resistance, although the first one-way switch S11 and the second one-way switch S12 are turned on, the load current still flows through the direct movable contact K. If it is detected that S1 bears the stage voltage U0, the moving contact is switched from the static contact R2A to R1A, and the one-way switch is triggered according to the direction of iK, and the detection unit detects the current iK through the contact K, when iK> When 0, the third one-way switch S21 is triggered to turn on the second bidirectional switch branch S2; when iK<0, the second one-way switch S22 is triggered to turn on the second bidirectional switch branch S2.

As the moving contact D1 moves, when moving to the position shown in Figure 4c, the first two-way switch branch S1 and the second two-way switch branch S2 are respectively connected to the static contact R1A and the static contact R2A, and at this time it is the switching action. The key link here is to realize arc-free switching of winding taps and avoid load open circuit or winding short circuit. During the movement from the state of Fig. 4b to the state of Fig. 4c, when the second bidirectional switch branch S2 is not connected to the static contact R2A, since the second bidirectional switch branch S2 is in a floating state, the switch voltage drops to zero; when When the moving contact D1 moves to the state shown in Figure 4c, since the second bidirectional switch branch S2 is in the off state, it must bear the winding level voltage U ₀ between the static contacts R1A and R2A, and by judging the second bidirectional switch branch S2 Whether the end bears the voltage is used as the criterion for the connection between the second bidirectional switch branch S2 and the static contact R2A, thereby eliminating the need for a mechanical position judging mechanism. When the detection unit in the control loop detects that the second bidirectional switch branch S2 bears the voltage, it starts the switching process from the first bidirectional switch branch S1 to the second bidirectional switch branch S2, and the direction data of the load current is required. The flow from the static contacts of group A to the first moving contact D1 is positive, that is, the current i>0, otherwise i<0. According to the load current direction and switching direction, that is, switching from the first bidirectional switching branch S1 to the second bidirectional switching branch S2 or switching from the second bidirectional switching branch S2 to the first bidirectional switching branch S2, there are four kinds of work The situation, as shown in Figure 6a-6d.

Figure 6a and Figure 6b show the switching process from the first bidirectional switch branch S1 to the second bidirectional switch branch S2, and Figure 6c and Figure 6d show the switching from the second bidirectional switch branch S2 to the first bidirectional switch branch S1 process, the switching process is explained below by taking FIG. 6a as an example, the operating condition is that the current i>0, and the first bidirectional switch branch S1 is switched to the second bidirectional switch branch S2.

When the movable contact D is in the position shown in Figure 4c, the first one-way switch S11 and the second one-way switch S12 are turned on, at this time the second two-way switch branch S2 bears the stage voltage U0, and the load current flows through the first The switch tube of a one-way switch S11 and the diode of the second one-way switch S12, that is, the state before time t1 in Fig. A certain time to t2, such as 3 microseconds, to ensure that the second one-way switch S12 is reliably turned off; at time t2, the third one-way switch S21 is turned on, and the load current flows through two branches at this time, including the first one-way switch S11 The switching tube of the switch tube and the diode of the second one-way switch S12 are used as one branch, and the switch tube of the third one-way switch S21 and the diode of the fourth one-way switch S22 are used as another branch, so as to ensure that the winding is not short-circuited during the switching process. The load is not open circuit, delay for a certain time to t3 to ensure that the current i drops to zero; turn off the first one-way switch S11 at time t3, the load current is all transferred to the second two-way switch branch S2, and delay to t4 to ensure The first one-way switch S11 is reliably turned off, and at this time, the load current flows through the switch tube of the third one-way switch S21 and the diode of the fourth one-way switch S22; The bidirectional switch branch S1 is completely turned off, and the second bidirectional switch branch S2 is completely turned on. When all the load current is transferred to the second bidirectional switch branch S2, the movable contact D1 continues to move, and when the first bidirectional switch branch S1 is disconnected from the static contact R1A, it will not cause the load to open and play the role of arc suppression.

In the switching process of Figure 4c, when the first bidirectional switch branch S1 is turned off, because the current in the inductor cannot change suddenly, an overvoltage will be formed in the winding of the transformer cut off part. At this time, the snubber circuit C3 forms a path, and the bidirectional The switch acts as a protection.

When the moving contact D1 moves to the position shown in Figure 4d, both the through contact K and the second bidirectional switch branch S2 are connected to the static contact R2A. Since the resistance of the through contact K is much smaller than that of the second bidirectional switch branch S2, the current Transfer to the straight-through contact K. When it is detected that the current i S2 of the second bidirectional switch branch _S2 suddenly decreases to close to zero, it can be judged that the straight-through contact has been connected to the static contact R2A. At this time, the trigger unit sends a trigger signal The second bidirectional switch branch S2 is turned off.

When the moving contact D moves to the position in Figure 4e, the first two-way switch branch S1 and the second two-way switch branch S2 are disconnected from the static contact R1A and the static contact R2A, and only the through contact K and the static contact R2A Connection, so far a switching process is complete.

The working principles of the other three working conditions are basically the same, which can be understood by referring to Figures 6b-6d, and will not be repeated here.

Figure 5 shows the moving process of the moving contact D2 and the moving contact D3. The same drive motor drives the three moving contacts to act simultaneously. The initial state is that the contact D2 is connected to the static contact R1B, and the moving contact D3 is connected to the static contact R2B. Connection, as shown in Figure 5a, at this time - the input stage voltage U ₀ at the input terminal of the control power supply unit, when switching to the state shown in Figure 5b, neither the second moving contact D2 nor the third moving contact D3 is in contact with any static contact At this time, there is no input at the input terminal of the control power supply unit, and the internal energy storage medium is used to discharge to provide power for the control circuit. When the moving contact D1 switches to the state shown in Figure 4e, the moving contact D2 and moving contact D3 switch to the state shown in Figure 4e. In state 5c, the input stage voltage U ₀ at the input terminal of the control power supply unit is controlled at this time, so far, a switching process of the moving contact D2 and the moving contact D3 is completely completed.

Fig. 7 is a perspective view of a transformer-integrated arcless on-load tap-changer according to a preferred embodiment of the present invention. The upper layer is the static contacts of group B, the moving contacts D2 and D3, and the control power supply unit , the lower layer is the static contact of group A and the moving contact D1 part, and the switch drive motor simultaneously drives three moving contacts for switching.

According to the working sequence when the full control device is used as shown in Figs. 6b-6d of the above embodiment, the control sequence when the half control device is used can be designed by analogy, and will not be repeated.

Above-mentioned process has explained working principle and basic composition of the present invention with single-phase winding as example, and the structure shown in Fig. 1 just can be used in three-phase structure through simple expansion, and the tap of three-phase on-load tap-changing transformer has three-phase star Structures such as neutral point taps, angled connection end taps, and angled connection center taps, etc., no matter which structure is used, does not affect the use of the present invention.

The foregoing is only an embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can be made without departing from the technical principle of the present invention. It should be regarded as the protection scope of the present invention.

The present invention realizes the arc-free switchover of the on-load tap changer by using the bidirectional switch and the trigger sequence control of the bidirectional switch, prevents the expansion of the accident when the bidirectional switch fails, ensures the reliable power supply of the control circuit, and has a simple structure and Works reliably.

The above embodiments are only used to illustrate the present invention, but not to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications or equivalent replacements of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention, and all should cover Within the scope of the claims of the present invention.

Claims (10)

1. transformer integral type is without an arc on load tap changer, comprise the fixed contact that is connected with transformer tapping, be connected with transformer terminal by motor-driven moving contact, it is characterized in that, also comprise control loop;

Described moving contact comprises the first bidirectional switch branch road, straight-through contact, the second bidirectional switch branch road that one end is connected with outlet terminal; After described the first switching branches and the second bidirectional switch branch road are connected by two electronic power switches, a buffer circuit in parallel, then be in series with a fuse;

Described control loop comprises trigger element and detecting unit; Described detecting unit detects electric current, the electric current of described straight-through contact, described the first bidirectional switch branch road, the electric current of the second bidirectional switch branch road and the pressure drop of pressure drop and adjacent two fixed contacts that described outlet terminal flows through, and the data that obtain are calculated to backward described trigger element issue control command, provide triggering signal by described trigger element for the electronic power switch of described the first bidirectional switch branch road, the second bidirectional switch branch road.

2. a kind of transformer integral type according to claim 1, without arc on load tap changer, is characterized in that, parallel connection buffer circuit between described the first bidirectional switch branch road and the second bidirectional switch branch road.

3. a kind of transformer integral type according to claim 1 and 2, without arc on load tap changer, is characterized in that, described buffer circuit is an electric capacity or resistance-capacitance circuit.

4. a kind of transformer integral type according to claim 1 is without arc on load tap changer, it is characterized in that, in moving contact moving process, described the first bidirectional switch branch road, straight-through contact, the second bidirectional switch branch road successively with being connected of described each fixed contact.

5. a kind of transformer integral type according to claim 1 is without arc on load tap changer, it is characterized in that, also comprise control power subsystem, described control power subsystem is made input stage voltage with the pressure drop of described adjacent two fixed contacts, and is described control loop power supply.

6. a kind of transformer integral type according to claim 5 is without arc on load tap changer, it is characterized in that, also comprise other one group of fixed contact being connected with transformer tapping, the pressure drop of wherein two adjacent fixed contacts of described other one group of fixed contact is described control power subsystem power supply.

7. a kind of transformer integral type according to claim 1 is without arc on load tap changer, it is characterized in that, described control loop also comprises communication unit and electric-motor drive unit, the data upload described detecting unit being detected by described communication unit is to host computer, by described PC control drive motor units, drive described moving contact action.

8. a kind of transformer integral type according to claim 1 is without arc on load tap changer, it is characterized in that, described control power subsystem is converted to direct voltage by isolation and the translation circuit of its inside by the step voltage of input, be described control loop power supply by discharge module, be its inner charging module charging simultaneously; The input stage voltage of described control power subsystem is 1 o'clock, is that described charging module is described control loop power supply by described discharge module.

9. a kind of transformer integral type according to claim 1, without arc on load tap changer, is characterized in that, described electronic power switch adopts the half control device of thyristor or the full control device of IGBT, MOSFET.

10. a kind of transformer integral type according to claim 9, without arc on load tap changer, is characterized in that, when described electric power electric switch adopts the half control device of thyristor, the form of being connected of two electronic power switches is that inverse parallel connects; When described electronic power switch adopts the full control device of IGBT, MOSFET, the form of being connected of two electronic power switches is that anti-series connects.