Selection switch, on-load voltage regulation tap switch and distribution transformer thereof
By using a selection switch combining silicon carbide N-type insulated gate bipolar transistors and RC circuits in the distribution transformer, arc-free switching is achieved, solving the problems of large arcing, long switching time and high failure rate of mechanical on-load tap-changing distribution transformers, and improving switching flexibility and failure rate.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG RONGDA POWER ENG CO LTD
- Filing Date
- 2025-12-09
- Publication Date
- 2026-05-05
AI Technical Summary
Existing mechanical on-load tap-changing distribution transformers have problems such as large arcing during switching, easy contamination of insulating oil, long mechanical switching action time, and limited tap adjustment range. They also have high operation and maintenance costs, high failure rate, and a high rate of cascading failures between multiple distribution transformers.
A selection switch combining silicon carbide N-type insulated gate bipolar transistors (SiC IGBTs) and RC circuits is designed, along with an arc-free switching function, to replace traditional tap changers and contacts. By using resistance to reduce the short-circuit current during high-voltage winding switching, an arc-free three-phase on-load tap changer transformer is designed to achieve multi-level regulation.
Arc-free switching was achieved, which reduced the failure rate, improved switching flexibility, reduced arcing and switching time, and lowered the failure rate of mechanical on-load tap-changing distribution transformers.
Smart Images
Figure CN121984487A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of on-load tap changer technology for distribution transformers, and particularly to a selector switch, an on-load tap changer splitter switch, and a distribution transformer thereof. Background Technology
[0002] The existing mechanical on-load tap-changing distribution transformers configured in the distribution substation have problems such as large arc light during switching, easy contamination of insulating oil, long mechanical switching action time, and limited tap adjustment number. In addition, the cost of later operation and maintenance is high, the risk of operation failure is high, and the cascading failure rate between multiple distribution transformers is high. Summary of the Invention
[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a selection switch, an on-load tap changer and its distribution transformer structure, which can solve the technical problems such as switching arcing that exist in the traditional mechanical on-load tap changer during voltage regulation.
[0004] In a first aspect, the present invention provides a selection switch, a first silicon carbide N-type insulated-gate bipolar transistor, a first RC circuit, a second RC circuit, and a second silicon carbide N-type insulated-gate bipolar transistor. The collector of the first silicon carbide N-type insulated gate bipolar transistor, the first terminal of the first RC circuit, the second terminal of the second RC circuit, and the emitter of the second silicon carbide N-type insulated gate bipolar transistor are connected; the emitter of the first silicon carbide N-type insulated gate bipolar transistor, the second terminal of the first RC circuit, the first terminal of the second RC circuit, and the collector of the second silicon carbide N-type insulated gate bipolar transistor are connected.
[0005] In a second aspect of the present invention, an on-load tap changer is provided, wherein the on-load tap changer is connected to a transformer winding tap, and the on-load tap changer includes a third resistor and a protection circuit, wherein the protection circuit includes the selector switch mentioned in the first aspect, one end of the protection circuit is connected to the tap, and the other end of the protection circuit is connected to the third resistor.
[0006] In a third aspect of this invention, a three-phase on-load tap changer transformer is provided, comprising an equivalent power source, three single-phase transformers connected in series, and the on-load tap changer mentioned in the second aspect. The on-load tap changer includes a third protection circuit, a fourth protection circuit, a fifth protection circuit, and the third resistor. The first single-phase transformer among the three single-phase transformers has a third tap, and the first terminal of the third protection circuit is connected to the third tap. The second single-phase transformer among the three single-phase transformers has a fourth tap, and the first terminal of the fourth protection circuit is connected to the fourth tap. The third single-phase transformer among the three single-phase transformers has a fifth tap, and the first terminal of the fifth protection circuit is connected to the fifth tap. The second terminals of the third protection circuit, the fourth protection circuit, and the fifth protection circuit are all connected to the first terminal of the third resistor. The first terminal of the equivalent power source is connected to the three single-phase transformers connected in series, and the second terminal of the equivalent power source is connected to the second terminal of the third resistor and grounded.
[0007] A fourth aspect of the present invention provides a distribution transformer, comprising: a three-phase on-load tap changer transformer mentioned in the third aspect, a tap changer module and a time control switch module, wherein the three-phase on-load tap changer transformer is coupled to a first terminal of the tap changer module, and the second terminal of the tap changer module is coupled to the time control switch module; The time-controlled switch module includes three single-phase transformers connected in series, a first time-controlled switch, a second time-controlled switch, a third time-controlled switch, a control module, and a load. The fourth single-phase transformer has a fourth tap, the fifth single-phase transformer has a fifth tap, and the sixth single-phase transformer has a sixth tap. The first terminal of the first time-controlled switch is connected to the fourth tap, the first terminal of the second time-controlled switch is connected to the fifth tap, and the first terminal of the third time-controlled switch is connected to the seventh tap. The second terminals of the first, second, and third time-controlled switches are all connected to the load. The control module controls the opening and closing of the first, second, and third time-controlled switches.
[0008] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, based on the characteristics of silicon carbide, such as high voltage resistance, strong current carrying capacity, and considerable service life, a selection switch is designed to achieve arc-free switching. By replacing the traditional tap changer and contacts with an on-load tap changer composed of an arc-free selection switch, the short-circuit current generated during the switching action of the high-voltage side winding can be reduced using resistance, preventing the selection switch from burning out and reducing the failure rate of the mechanical on-load tap-changing distribution transformer. Furthermore, the transformer and its distribution transformer containing the arc-free three-phase on-load tap-changing switch can achieve multi-level adjustment, improving the switching flexibility of the distribution transformer and reducing the problems of large arcs and long switching times. Attached Figure Description
[0009] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.
[0010] Figure 1 This is a schematic diagram of a selection switch provided in an embodiment of the present invention.
[0011] Figure 2 This is a circuit topology diagram of an on-load tap changer provided in an embodiment of the present invention.
[0012] Figure 3 This is a circuit topology diagram of a three-phase on-load tap-changing split-type transformer provided in an embodiment of the present invention.
[0013] Figure 4 This is a circuit topology diagram of a distribution transformer provided in an embodiment of the present invention.
[0014] Figure 5 This is a schematic diagram of the control process for automatic voltage regulation of a distribution transformer provided in an embodiment of the present invention.
[0015] Figure 6 These are the change curves of various electrical variables when the voltage of the distribution transformer is increased, provided in the embodiments of the present invention. Among them, a is the voltage waveform diagram of the power supply side, b is the voltage waveform diagram of the transformer secondary side, c is the voltage waveform diagram of the load side, and d is the power diagram of the load side.
[0016] Explanation of reference numerals in the attached diagram: 1-First silicon carbide N-type insulated gate bipolar transistor; 2-First RC circuit; 21-First resistor; 22-First capacitor; 3-Second RC circuit; 31-Second resistor; 32-Second capacitor; 4-Second silicon carbide N-type insulated gate bipolar transistor; 5-Third resistor; 6-Protection circuit; 61-First protection circuit; 62-Second protection circuit; 7-Equivalent power supply; 8-Single-phase transformer; 9-Third protection circuit; 10-Fourth protection circuit; 11-Fifth protection circuit; 12-Voltage regulating module; 13-Time control switch module; 14-Load; Z-Tap; Z1-First tap; Z2-Second tap; A-First selector switch; B-Second selector switch; C-Third selector switch; D-Fourth selector switch; E-Fifth selector switch; F-Sixth selector switch; G-Seventh selector switch; H-Eighth selector switch; I-Ninth selector switch; U21-First single-phase transformer; U31-Second single-phase transformer; U41-Third single-phase transformer. Detailed Implementation
[0017] To enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0018] Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts disclosed in this invention.
[0019] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention.
[0020] Reference manual attached Figures 1 to 5 This invention provides a selection switch, such as... Figure 1 As shown, this is applied to a distribution transformer and includes: a first silicon carbide N-type insulated gate bipolar transistor 1, a first RC circuit 2, a second RC circuit 3, and a second silicon carbide N-type insulated gate bipolar transistor 4. The collector of the first silicon carbide N-type insulated gate bipolar transistor, the first terminal of the first RC circuit, the second terminal of the second RC circuit, and the emitter of the second silicon carbide N-type insulated gate bipolar transistor are connected; the emitter of the first silicon carbide N-type insulated gate bipolar transistor, the second terminal of the first RC circuit, the first terminal of the second RC circuit, and the collector of the second silicon carbide N-type insulated gate bipolar transistor are connected.
[0021] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, a selection switch is designed based on the characteristics of silicon carbide, such as high withstand voltage, strong current carrying capacity, and considerable service life, thereby realizing arc-free switching function. The silicon carbide N-type insulated-gate bipolar transistor (SiCIGBT) also carries an anti-parallel diode to provide a current path when the IGBT is turned off. The first silicon carbide N-type insulated-gate bipolar transistor 1 is connected in parallel with the first RC circuit 2, wherein the first RC circuit 2 prevents the first silicon carbide N-type insulated-gate bipolar transistor 1 from burning out due to overvoltage during the turn-off process. Similarly, the second silicon carbide N-type insulated-gate bipolar transistor 4 is connected in parallel with the second RC circuit 3, wherein the second RC circuit 3 prevents the second silicon carbide N-type insulated-gate bipolar transistor 4 from burning out due to overvoltage during the turn-off process, thus preventing arcing when using this selection switch.
[0022] In one possible implementation, the first RC circuit 2 includes a first resistor 21 and a first capacitor 22. The first end of the first resistor 21 is the first terminal of the first RC circuit 2, and the second end of the first resistor 21 is connected to the first terminal of the first capacitor 22. The second terminal of the first capacitor 22 is the second terminal of the first RC circuit 2. The second RC circuit 3 includes a second resistor 31 and a second capacitor 32. The first end of the second resistor 31 is the first terminal of the second RC circuit 3, and the second end of the second resistor 31 is connected to the first terminal of the second capacitor 32. The second terminal of the second capacitor 31 is the second terminal of the second RC circuit 3. The first RC circuit 2 is used to absorb the overvoltage generated during the turn-off process of the first silicon carbide N-type insulated-gate bipolar transistor 1, and the second RC circuit 3 is used to absorb the overvoltage generated during the turn-off process of the second silicon carbide N-type insulated-gate bipolar transistor 4. That is, the combination of the first silicon carbide N-type insulated-gate bipolar transistor and the first RC circuit is connected in anti-parallel with the combination of the second silicon carbide N-type insulated-gate bipolar transistor and the second RC circuit.
[0023] In one possible implementation, if the selector switch is placed in a 10kV / 0.4kV dry-type distribution transformer, then the maximum peak voltage that the first SiC IGBT 1 and the second SiC IGBT 2 need to withstand is approximately 1414V. In this case, the resistance of the first resistor and the second resistor is 40Ω, and the capacitance of the first capacitor and the second capacitor is 0.2μF.
[0024] This invention also provides an on-load tap changer, such as... Figure 2 As shown, the on-load tap changer is connected to the transformer winding tap z. The on-load tap changer includes a third resistor 5 and a protection circuit 6. The protection circuit includes a selector switch as mentioned in the first aspect. One end of the protection circuit 6 is connected to the tap z, and the other end of the protection circuit 6 is connected to the third resistor 5.
[0025] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, the arc-free selector switch mentioned in the first aspect is applied as a protection circuit to an on-load tap changer. This on-load tap changer replaces the traditional tap changer and contacts. The transformer winding is a high-voltage side winding, and the transformer winding includes multiple taps, which can be two, three, or more. The third resistor 5 is a transition resistor, which can reduce the short-circuit current generated during switching operations and prevent IGBT burnout. This on-load tap changer reduces the failure rate of traditional electromechanical mechanisms. In other words, it has a lower failure rate than the traditional mechanical topology and can effectively reduce the cascading failure rate.
[0026] In one possible implementation, when the tap Z includes a first tap Z1 and a second tap Z2, the protection circuit includes a first protection circuit 61 and a second protection circuit 62, the first protection circuit 61 being connected to the first tap Z1, the second protection circuit 62 being connected to the second tap Z2, and the first protection circuit 61 and the second protection circuit 62 being connected to the third resistor 5.
[0027] In one possible embodiment, the first protection circuit 61 includes a first selector switch A and a third selector switch C, and the second protection circuit 62 includes a second selector switch B and a fourth selector switch D. The first end of the first selector switch A and the first end of the third selector switch C are connected to the first tap Z1. The first end of the second selector switch B and the first end of the fourth selector switch D are connected to the second tap Z2. The second end of the third selector switch C and the second end of the fourth selector switch D are connected to the first end of the third resistor 5. The second end of the first selector switch A is connected to the second end of the second selector switch B.
[0028] In this on-load tap changer, the switching action is as follows: If the on-load tap changer is operating at the first tap Z1 position, the first selector switch A is on, and the second selector switch B, the third selector switch C, and the fourth selector switch D are off. Current flows through the first tap Z1 and the first selector switch A. Next, due to the increased low-voltage side voltage due to load shedding, it needs to switch to the second tap Z2 position to reduce the low-voltage side voltage. Subsequently, the fourth selector switch D is on, and current flows through the second tap Z2, the fourth selector switch D, and the third resistor 5. The third resistor reduces the short-circuit current in the circuit from the first tap Z1 to the second tap Z2, the fourth selector switch D, the third resistor 5, the first selector switch A, and the first tap Z1. Then, the first selector switch A is off, and the second selector switch B is on, with current flowing through the second tap Z2 and the second selector switch B. Similarly, the third resistor 5 reduces the short-circuit current in the circuit from the second selector switch B to the third resistor 5, the fourth selector switch D, and the second selector switch B. Then, the fourth switch module D is turned off to complete the switching between taps, achieving arc-free, fast, and flexible voltage regulation.
[0029] In one possible implementation, if the selector switch is installed in a 10kV / 0.4kV dry-type distribution transformer, then the resistance of the third resistor is 6Ω.
[0030] This invention also provides a three-phase on-load tap-changing split-type transformer, such as... Figure 3 As shown, the equivalent power source 7, three single-phase transformers 8 connected in series, and the on-load tap changer mentioned in the second aspect of claim are included. The on-load tap changer includes a third protection circuit 9, a fourth protection circuit 10, a fifth protection circuit 11, and the third resistor 5. The first single-phase transformer U21 of the three single-phase transformers has a third tap, and the first end of the third protection circuit 9 is connected to the third tap. The second single-phase transformer U31 of the three single-phase transformers has a fourth tap, and the first end of the fourth protection circuit 10 is connected to the fourth tap. The third single-phase transformer U41 of the three single-phase transformers has a fifth tap, and the first end of the fifth protection circuit 11 is connected to the fifth tap. The second ends of the third protection circuit 9, the fourth protection circuit 10, and the fifth protection circuit 11 are all connected to the first end of the third resistor. The first end of the equivalent power source 7 is connected to the three single-phase transformers connected in series, and the second end of the equivalent power source 7 is connected to the second end of the third resistor and grounded.
[0031] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, a three-phase on-load tap changer transformer with an arc-free selector switch is constructed by connecting three single-phase transformer windings in series. Because it has three single-phase transformer windings, it can form three adjustment positions, thereby realizing multi-position adjustment, improving switching flexibility, and reducing the problems of large arc and long time during switching.
[0032] In one possible embodiment, the third protection circuit 9 includes a fifth selector switch E and an eighth selector switch H; the fourth protection circuit 10 includes a sixth selector switch F and a ninth selector switch I; and the fifth protection circuit 11 includes a seventh selector switch G and a tenth selector switch J. The first terminals of the fifth selector switch E and the eighth selector switch H are both connected to the third tap; the first terminals of the sixth selector switch F and the ninth selector switch I are both connected to the fourth tap; and the first terminals of the seventh selector switch G and the tenth selector switch J are both connected to the fifth tap. The second terminals of the eighth selector switch H, the ninth selector switch I, and the tenth selector switch J are all connected to the first terminal of the third resistor. The second terminals of the fifth selector switch E, the sixth selector switch F, and the seventh selector switch G are interconnected and grounded.
[0033] This invention also provides a distribution transformer, such as... Figure 4 As shown in the third aspect, the three-phase on-load tap-changing decomposition switch transformer, the tap-regulating module 12 and the time-control switch module 13 are coupled to the first end of the tap-regulating module and the second end of the tap-regulating module is coupled to the time-control switch module. The time-controlled switch module includes three single-phase transformers connected in series, a first time-controlled switch S1, a second time-controlled switch S2, a third time-controlled switch S3, a control module, and a load 14. The fourth single-phase transformer among the three single-phase transformers has a fourth tap, the fifth single-phase transformer among the three single-phase transformers has a fifth tap, and the sixth single-phase transformer among the three single-phase transformers has a sixth tap. The first end of the first time-controlled switch is connected to the fourth tap, the first end of the second time-controlled switch is connected to the fifth tap, and the first end of the third time-controlled switch is connected to the seventh tap. The second ends of the first time-controlled switch, the second end of the second time-controlled switch, and the second end of the third time-controlled switch are all connected to the load. The control module controls the opening and closing of the first time-controlled switch S1, the second time-controlled switch S2, and the third time-controlled switch S3.
[0034] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, the arc-free three-phase on-load tap changer transformer and its distribution transformer can achieve multi-level adjustment, which improves the switching flexibility of the distribution transformer and reduces the problems of large arc and long switching time.
[0035] In this distribution transformer, the switching action is as follows: If the voltage across load 14 rises, this process is achieved by switching the time-controlled switch module 13 on and off, switching the tap to reduce the low-voltage side voltage; the second tap is working, the sixth selector switch F is working, and the switch will switch to the seventh selector switch module G; first, the tenth selector switch J is turned on, and the current flows through the third tap, the tenth selector switch module J, and the third resistor 5. The third resistor 5 reduces the short-circuit current of the circuit from the third tap to the tenth selector switch J to the sixth selector module F and back to the third tap. After a delay of 10ms, the sixth selector switch F is turned off, after a delay of 10ms, the seventh selector switch G is turned on, after a delay of 10ms, the third resistor 5 reduces the short-circuit current of the circuit from the seventh selector switch G to the third resistor 5 to the tenth selector switch J and back to the seventh selector switch G. Then, the tenth selector switch J is turned off, completing the switching from the second tap to the third tap.
[0036] In another embodiment of the present invention, the control process for the distribution transformer mentioned in the fourth aspect is as follows: Figure 5 As shown, voltage regulation begins by determining if the load voltage is within the allowable range. If the load voltage meets the requirements, a cyclic detection is initiated; otherwise, it checks if the load voltage is less than 0.95 times the rated value. If "yes," it checks if the fifth selector switch E is on; if "yes," it enters the cyclic detection phase. If "no," it enters the zero-crossing detection phase, turning on the eighth selector switch H and checking if the seventh selector switch G is on. If "yes," it turns off the seventh selector switch G and turns on the sixth selector switch F; if "no," it turns off the sixth selector switch F and turns on the fifth selector switch E, then turns off the eighth selector switch H and enters the cyclic detection phase again. Similarly, it checks if the seventh selector switch G is on to complete the corresponding process. This voltage regulation process ensures continuous load current while using the third resistor 5 to reduce short-circuit current and prevent IGBT burnout.
[0037] For the circuit topology in the scheme, corresponding numerical matching is performed to conduct simulation. The parameters of the on-load tap changer for a 10kV / 0.4kV dry-type distribution transformer will be designed. Assuming a three-phase short circuit occurs on the low-voltage side and the high-voltage side is connected to an infinite system, the maximum short-circuit current on the high-voltage side of the transformer will be calculated:
[0038] In the formula, Rsc and Xsc are the short-circuit resistance and short-circuit reactance referred to the high-voltage side of the transformer, respectively, with a value of 3.45 + j27.78Ω. U1 is 10kV. The maximum short-circuit current can be calculated to be about 206A through formula (1), with a corresponding peak value of about 292A. Therefore, an IGBT with a rated current of 300A is selected.
[0039] If the transformer has n adjustable taps both above and below the main tap, and D% is the percentage of the winding voltage between two adjacent taps relative to the rated voltage, the highest voltage between the taps can be calculated as follows: Furthermore, the maximum peak voltage that the IGBT can withstand is analyzed as follows:
[0040] In the formula, k is a reliability coefficient that takes into account factors such as load fluctuations and voltage fluctuations, and its value is 1.2. Substituting the values, the maximum peak voltage that the IGBT can withstand is approximately 1414V, and thus an IGBT with a rated voltage of 1700V and a rated current of 300A is selected.
[0041] During the contact switching transition, the third resistor 5 will be used to limit the short-circuit current and ensure continuous load current. The resistance value of the third resistor should be reasonably selected considering the magnitude of the short-circuit current to protect the IGBT.
[0042] After R is connected, the short-circuit current will consist of a DC transient component and an AC periodic forced component, from which the loop current calculation formula can be derived:
[0043] In the formula, I ini This is the initial value of the short-circuit current.
[0044] Resistance and R e +R, Inductance L e This will affect the magnitude of the short-circuit current; the larger R is, the greater the DC transient component I. dc, ini The faster the decay, the smaller the amplitude of the AC period forced component, which can better reduce the magnitude of the short-circuit current. During the transition process, the equivalent impedance of the winding leakage impedance of the transformer selected in this paper is 1.6+j1.88. In order to limit the short-circuit current to below 90A, R is selected as 6Ω by calculation through equation (3).
[0045]
[0046] Figure 1 The RC circuit in the middle can reduce the overvoltage when the IGBT is turned off, thus preventing damage to the IGBT. The working principle is that the capacitor C absorbs the inductance L when the IGBT is turned off. e The stored energy can be released when the IGBT is turned on. Based on this, the designed R and C must satisfy equation (5).
[0047]
[0048] In the formula, I is the IGBT's turn-off current, ΔU is the overvoltage across the equivalent inductor, and t0 is the IGBT's on-time. Let the maximum voltage across capacitor C be U. max Given that the grid frequency is f, the formula for calculating the active power consumed by the resistor can be derived, as shown in formula (6).
[0049]
[0050] Inductor L e The values of R and C have a significant impact, while the inductance value is not easily obtained. With R and C at 40Ω and 0.2μF respectively, the active power consumed can be calculated to be 40W, and the following can be obtained: Figure 6 Multiple simulation waveforms.
[0051] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention.
Claims
1. A selector switch, applied to a distribution transformer, characterized in that, include: A first silicon carbide N-type insulated-gate bipolar transistor, a first RC circuit, a second RC circuit, and a second silicon carbide N-type insulated-gate bipolar transistor. The collector of the first silicon carbide N-type insulated gate bipolar transistor, the first terminal of the first RC circuit, the second terminal of the second RC circuit, and the emitter of the second silicon carbide N-type insulated gate bipolar transistor are connected; the emitter of the first silicon carbide N-type insulated gate bipolar transistor, the second terminal of the first RC circuit, the first terminal of the second RC circuit, and the collector of the second silicon carbide N-type insulated gate bipolar transistor are connected.
2. The selection switch according to claim 1, characterized in that, The first RC circuit includes a first resistor and a first capacitor. The first end of the first resistor is the first end of the first RC circuit, and the second end of the first resistor is connected to the first end of the first capacitor. The second end of the first capacitor is the second end of the first RC circuit. The second RC circuit includes a second resistor and a second capacitor. The first end of the second resistor is the first end of the second RC circuit, and the second end of the second resistor is connected to the first end of the second capacitor. The second end of the second capacitor is the second end of the second RC circuit. The first RC circuit is used to absorb the overvoltage generated by the first silicon carbide N-type insulated gate bipolar transistor during the turn-off process, and the second RC circuit is used to absorb the overvoltage generated by the second silicon carbide N-type insulated gate bipolar transistor during the turn-off process.
3. The selection switch according to claim 2, characterized in that, The resistance of the first resistor and the second resistor is 40Ω, and the capacitance of the first capacitor and the second capacitor is 0.2μF.
4. An on-load tap changer, characterized in that, The on-load tap changer is connected to the transformer winding tap. The on-load tap changer includes a third resistor and a protection circuit. The protection circuit includes a selector switch as described in any one of claims 1-3. One end of the protection circuit is connected to the tap, and the other end of the protection circuit is connected to the third resistor.
5. The on-load tap changer according to claim 4, characterized in that, When the tap includes a first tap and a second tap, the protection circuit includes a first protection circuit and a second protection circuit. The first protection circuit is connected to the first tap, the second protection circuit is connected to the second tap, and the first protection circuit and the second protection circuit are connected to the third resistor.
6. The on-load tap changer according to claim 5, characterized in that, The first protection circuit includes a first selection switch and a third selection switch, and the second protection circuit includes a second selection switch and a fourth selection switch. The first end of the first selection switch and the first end of the third selection switch are connected to the first tap. The first end of the second selection switch and the first end of the fourth selection switch are connected to the second tap. The second ends of the third selection switch and the second ends of the fourth selection switch are connected to the first end of the third resistor. The second end of the first selection switch is connected to the second end of the second selection switch.
7. The on-load tap changer according to claim 6, characterized in that, The resistance of the third resistor is 6Ω.
8. A three-phase on-load tap-changing split-type transformer, characterized in that, The device includes an equivalent power source, three single-phase transformers connected in series, and an on-load tap changer as described in any one of claims 4-7. The on-load tap changer includes a third protection circuit, a fourth protection circuit, a fifth protection circuit, and the third resistor. The first single-phase transformer among the three single-phase transformers has a third tap, and the first terminal of the third protection circuit is connected to the third tap. The second single-phase transformer among the three single-phase transformers has a fourth tap, and the first terminal of the fourth protection circuit is connected to the fourth tap. The third single-phase transformer among the three single-phase transformers has a fifth tap, and the first terminal of the fifth protection circuit is connected to the fifth tap. The second terminals of the third protection circuit, the fourth protection circuit, and the fifth protection circuit are all connected to the first terminal of the third resistor. The first terminal of the equivalent power source is connected to the three single-phase transformers connected in series, and the second terminal of the equivalent power source is connected to the second terminal of the third resistor and grounded.
9. The three-phase on-load tap-changing transformer according to claim 8, wherein the third protection circuit includes a fifth selector switch and an eighth selector switch, the fourth protection circuit includes a sixth selector switch and a ninth selector switch, the fifth protection circuit includes a seventh selector switch and a tenth selector switch, the first terminals of the fifth selector switch and the eighth selector switch are both connected to the third tap, the first terminals of the sixth selector switch and the ninth selector switch are both connected to the fourth tap, and the first terminals of the seventh selector switch and the tenth selector switch are both connected to the fifth tap. The second terminals of the eighth, ninth, and tenth selector switches are all connected to the first terminal of the third resistor. The second terminals of the fifth, sixth, and seventh selector switches are interconnected and grounded.
10. A distribution transformer, characterized in that, include: The three-phase on-load tap-changing decomposition switch transformer, the tap-changing module, and the time-control switch module as described in any one of claims 8-9, wherein the three-phase on-load tap-changing decomposition switch transformer is coupled to the first end of the tap-changing module, and the second end of the tap-changing module is coupled to the time-control switch module; The time-controlled switch module includes three single-phase transformers connected in series, a first time-controlled switch, a second time-controlled switch, a third time-controlled switch, a control module, and a load. The fourth single-phase transformer has a fourth tap, the fifth single-phase transformer has a fifth tap, and the sixth single-phase transformer has a sixth tap. The first terminal of the first time-controlled switch is connected to the fourth tap, the first terminal of the second time-controlled switch is connected to the fifth tap, and the first terminal of the third time-controlled switch is connected to the seventh tap. The second terminals of the first, second, and third time-controlled switches are all connected to the load. The control module controls the opening and closing of the first, second, and third time-controlled switches.