Automatic on-load voltage regulation distribution transformer and voltage regulation method

Abstract

The present invention discloses an automatic on-load voltage-regulating distribution transformer and a voltage regulation method. The transformer has three-phase windings, each phase of which includes a low-voltage winding, a high-voltage winding 1, a high-voltage winding 2, an adjustable winding assembly 1, an adjustable winding assembly 2, and a controller. The high-voltage winding 1, the adjustable winding assembly 1, the adjustable winding assembly 2, and the high-voltage winding 2 are sequentially connected in series to form a high-voltage winding. The low-voltage winding is coupled to the high-voltage winding. The controller receives a voltage signal from the low-voltage winding and controls the connection with the adjustable winding assembly 1 and the adjustable winding assembly 2. The voltage regulation method operates the adjustable winding assembly 1 and the adjustable winding assembly 2 according to the current low-voltage winding voltage to achieve voltage regulation. The present invention combines the advantages of low loss of a mechanical on-load tap changer with the arc-free and impact-free switching of a power electronic on-load tap changer, and has the characteristics of simple structure, small size, arc-free, low power consumption, and continuous power supply during the switching process.

Description

Technical Field

[0001] The invention relates to an automatic on-load voltage regulation distribution transformer and a voltage regulation method, belonging to the technical field of on-load voltage regulation of distribution transformers. Background Art

[0002] Voltage quality is a key indicator of power grid service quality, particularly the magnitude of supply voltage deviation. This directly impacts the quality and output of industrial products, disrupts people's normal work and daily lives, and affects the safe and economic operation of the power grid. Currently, "low voltage" has become one of the most significant issues affecting abnormal operation of distribution networks. The most commonly used voltage control technology in distribution networks is voltage regulation via distribution transformers, which can be categorized as off-circuit voltage regulation and on-load voltage regulation. Currently, the predominant off-circuit voltage regulation method of distribution transformers is no longer sufficient to meet the voltage regulation needs of distribution substations; traditional mechanical switches still dominate the on-load voltage regulation of distribution transformers. With the development of smart grids, mechanical on-load tap-changers (OLTs), with their inherent problems caused by mechanical contacts, have become increasingly apparent. In recent years, power electronic OLT technology has rapidly advanced. While addressing the inherent issues of traditional mechanical OLTs, it also presents some shortcomings.

[0003] At present, the main technical difficulties of the known on-load tap-changing distribution transformers include:

[0004] (1) The tap contacts of the mechanical on-load tap changer generate arcs during the switching process, which can easily burn the contacts and cause oil pollution, affecting the insulation characteristics and service life of the transformer; the voltage regulation response speed is slow and the efficiency is low, with a lag of 100 milliseconds to several seconds; the mechanical transmission structure is complex, the failure rate is high, and the maintenance workload is large.

[0005] (2) Power electronic on-load tap-changers have high performance requirements for components such as thyristors and use a large number of components, resulting in problems such as high power consumption, complex control and high cost. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an automatic on-load voltage-regulating distribution transformer and a voltage-regulating method, which combines the advantages of low loss of a mechanical on-load tap changer and arc-free and impact-free switching of a power electronic on-load tap changer, and has the characteristics of simple structure, small size, no arcing, low power consumption, and no power outage during the switching process.

[0007] In order to solve the technical problem, the technical solution adopted by the present invention is: an automatic on-load tap-changing distribution transformer, which has a three-phase winding, each phase winding includes a low-voltage winding, a high-voltage winding 1, a high-voltage winding 2, an adjustable winding assembly 1, an adjustable winding assembly 2 and a controller, the high-voltage winding 1, the adjustable winding assembly 1, the adjustable winding assembly 2, and the high-voltage winding 2 are connected in series in sequence to form a high-voltage winding, the low-voltage winding is coupled to the high-voltage winding, and the controller receives the voltage signal of the low-voltage winding and is controlled and connected with the adjustable winding assembly 1 and the adjustable winding assembly 2.

[0008] Furthermore, the adjustable winding assembly 1 includes a voltage regulating winding 1 connected to the high-voltage winding 1, a plurality of voltage regulating switches connected to the tapping terminal of the voltage regulating winding 1, a voltage regulating switching mechanism 1, and a voltage regulating switching mechanism 2. One end of the plurality of voltage regulating switches is connected to the corresponding tapping terminal of the voltage regulating winding 1, and the other end is connected to the voltage regulating switching mechanism 1 or the voltage regulating switching mechanism 2 in a manner that two adjacent voltage regulating switches are respectively connected to different voltage regulating switching mechanisms. The other ends of the voltage regulating switching mechanism 1 and the voltage regulating switching mechanism 2 are both connected to point P.

[0009] The adjustable winding assembly 2 includes a voltage regulating winding 2 connected to the high-voltage winding 2, a plurality of voltage regulating switches connected to the tapping outlet of the voltage regulating winding 2, a voltage regulating switching mechanism 3, and a voltage regulating switching mechanism 4. One end of each of the plurality of voltage regulating switches is connected to the corresponding tapping outlet of the voltage regulating winding 2, and the other end is connected to the voltage regulating switching mechanism 3 or the voltage regulating switching mechanism 4 in a manner such that two adjacent voltage regulating switches are respectively connected to different voltage regulating switching mechanisms. The other ends of the voltage regulating switching mechanism 3 and the voltage regulating switching mechanism 4 are both connected to point Q.

[0010] Point P and point Q are connected to form a conductive circuit.

[0011] Furthermore, the voltage regulating switching mechanism includes an arc extinguishing switch, an IGBT module and a transition device. The IGBT module and the transition device are connected in series to form a transition circuit during the switching process. The arc extinguishing switch is a conduction circuit for the normal operation of the voltage regulating switching mechanism and is connected in parallel with the transition circuit.

[0012] Furthermore, the controller includes an isolation step-down unit, a power supply unit, a voltage sampling unit, a zero-crossing detection unit, a reset circuit, a single-chip microcomputer control unit, an IGBT trigger drive unit and a control signal output unit. The input end of the isolation step-down unit is connected to the secondary side of the distribution transformer, the power supply unit, the voltage sampling unit, and the zero-crossing detection unit are connected between the output end of the isolation step-down unit and the input end of the single-chip microcomputer control unit, the reset circuit is connected to the single-chip microcomputer control unit, and the IGBT trigger drive unit and the control signal output unit are connected to the output end of the single-chip microcomputer control unit for sending a voltage regulation trigger signal to the adjustable winding assembly.

[0013] Furthermore, the transition device is a transition resistor or a transition inductor.

[0014] Furthermore, the voltage regulating switch and arc suppression switch both adopt short-circuit-resistant magnetic latching relays.

[0015] Furthermore, the low-voltage winding is equipped with a voltage measuring device, which directly measures and sends the voltage value of the three-phase low-voltage winding to the controller. The voltage value includes each phase-to-ground voltage value of the three-phase low-voltage winding and the line voltage value between the three-phase low-voltage windings.

[0016] Furthermore, the three-phase low-voltage winding adopts a star connection method, with a neutral point led out and grounded; the three-phase high-voltage winding adopts a triangle or star connection method, with no neutral point or the neutral point is not led out, and the voltage regulating winding adopts a single-bridge cross-connection voltage regulation method.

[0017] The present invention also discloses an automatic on-load voltage regulation and distribution transformation and voltage regulation method, comprising the following steps:

[0018] S01) monitor the operating status of the distribution transformer in real time and detect the voltage value of the low-voltage winding through a voltage measuring device;

[0019] S02) Determine whether the voltage value of the low-voltage winding is qualified. If qualified, continue real-time monitoring. If unqualified, the controller calculates the voltage regulation strategy corresponding to the current low-voltage winding voltage and generates a voltage regulation logic control signal according to the voltage regulation strategy;

[0020] S03) Switch the adjustable winding components according to the voltage regulation logic control signal to complete the voltage regulation action.

[0021] Furthermore, the process of switching the adjustable winding component according to the voltage regulation logic control signal is as follows:

[0022] S31), closing a voltage regulating switch connected to the voltage regulating switching mechanism in the disconnected state;

[0023] S32), closing the IGBT module in the normal working conduction state voltage regulating switching mechanism, so that the voltage regulating switching mechanism is in the switching process conduction state;

[0024] S33), disconnecting the arc-extinguishing switch in the voltage-regulating switching mechanism described in step S32, so that the voltage-regulating switching mechanism is in a transitional conductive state;

[0025] S34), closing the IGBT module in the voltage regulating switching mechanism in step S31, so that the voltage regulating switching mechanism is in a transition process conducting state;

[0026] S35), disconnecting the IGBT module in the voltage regulating switching mechanism in step S32, so that the voltage regulating switching mechanism is in an off state;

[0027] S36) disconnecting the voltage regulating switch in the original closed state;

[0028] S37), closing the arc suppression switch in the voltage regulating switching mechanism described in step S31, so that the voltage regulating switching mechanism is in a conducting state during the switching process;

[0029] S38) disconnecting the IGBT module of the voltage regulation switching mechanism in step S31, so that the voltage regulation switching mechanism is in a normal working state, completing the voltage regulation switching process.

[0030] Furthermore, a single or multiple adjustable winding components are switched according to the voltage regulation logic control signal, and multiple adjustable winding components are operated individually or simultaneously. When controlling the action of each voltage regulation switching mechanism, the IGBT module must be operated first, and then the arc suppression switch must be operated. The operations include closing and opening.

[0031] The beneficial effects of the present invention are as follows: The present invention combines the advantages of low losses of a mechanical on-load tap changer with the arc-free and shock-free switching of a power electronic on-load tap changer, resulting in a simple structure, compact size, arc-free operation, low power consumption, and continuous power supply during the switching process. The voltage-regulating switching mechanism includes a transition circuit and a conduction circuit. The voltage-regulating switch and arc-extinguishing switch utilize short-circuit-resistant magnetic latching relays, which have a mechanical durability of over 1 million cycles and can withstand short-circuit currents (approximately 25 times the rated current) while consuming only 1.5 to 3W. The selected IGBT module is a fully controlled power electronic device, used only for opening and closing the transition circuit during the voltage-regulating switching process. It is not connected to the conduction circuit during normal transformer operation. This not only prevents heating caused by the IGBT conducting current for extended periods of time, but also increases the overall lifespan of the device. The transition device limits the circulating current generated when two taps are connected in parallel during the voltage-regulating switching process, preventing inter-stage short circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the circuit structure of the automatic on-load voltage-regulating distribution transformer device provided by the present invention;

[0033] Figure 2 Schematic diagram of the circuit structure of the voltage regulating switching mechanism in the present invention in the disconnected state;

[0034] Figure 3 This is a schematic diagram of the circuit structure of the voltage regulating switching mechanism of the present invention in a normal working conduction state;

[0035] Figure 4 Schematic diagram of the circuit structure of the voltage regulating switching mechanism in the present invention when it is in the conducting state during the switching process;

[0036] Figure 5 Schematic diagram of the circuit structure of the voltage regulating switching mechanism in the present invention in a transition process conducting state;

[0037] Figure 6 Schematic diagram of the structure of the controller in the present invention;

[0038] Figure 7 This is a flow chart of the voltage regulation method of the present invention;

[0039] Figure 8 Schematic diagram of the circuit structure in the rated tap state according to an embodiment of the present invention;

[0040] Figure 9 Schematic diagram of the circuit structure after the voltage regulating switch K7 is closed in an embodiment of the present invention;

[0041] Figure 10 Schematic diagram of the circuit structure of the voltage regulating switching mechanism 3 in the conductive state according to an embodiment of the present invention;

[0042] Figure 11 Schematic diagram of the circuit structure of the voltage regulating switching mechanism 4 in the disconnected state according to an embodiment of the present invention;

[0043] Figure 12 Schematic diagram of the circuit structure in the tapping state after voltage regulation is completed in an embodiment of the present invention. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0045] Example 1

[0046] This embodiment discloses an automatic on-load tap-changing distribution transformer having three-phase windings, such as Figure 1 As shown, each phase winding includes a low-voltage winding, a high-voltage winding 1, a high-voltage winding 2, an adjustable winding assembly 1, an adjustable winding assembly 2 and a controller. The high-voltage winding 1, the adjustable winding assembly 1, the adjustable winding assembly 2 and the high-voltage winding 2 are connected in series in sequence to form a high-voltage winding. The low-voltage winding is coupled to the high-voltage winding. The controller receives the voltage signal of the low-voltage winding and is controlled and connected to the adjustable winding assembly 1 and the adjustable winding assembly 2.

[0047] The adjustable winding assembly 1 includes: a voltage regulating winding 1 connected to a high voltage winding 1, a plurality of voltage regulating switches (K2, K4, K6, K8) connected to the tapping end of the voltage regulating winding 1, a voltage regulating switching mechanism 1, and a voltage regulating switching mechanism 2.

[0048] Among them, one end of the voltage regulating switch K8 and the voltage regulating switch K4 is connected to the tap corresponding to the voltage regulating winding 1, and the other end is connected to point E; one end of the voltage regulating switching mechanism 1 is connected to point E, and the other end is connected to point P; one end of the voltage regulating switch K6 and the voltage regulating switch K2 is connected to the tap corresponding to the voltage regulating winding 1, and the other end is connected to point F; one end of the voltage regulating switching mechanism 2 is connected to point F, and the other end is connected to point P.

[0049] The adjustable winding assembly 2 includes: a voltage regulating winding 2 connected to the high voltage winding 2, a plurality of voltage regulating switches (K3, K5, K7, K9) connected to the tapping end of the voltage regulating winding 2, a voltage regulating switching mechanism 3, and a voltage regulating switching mechanism 4.

[0050] Among them, one end of the voltage regulating switch K3 and the voltage regulating switch K7 is connected to the tap corresponding to the voltage regulating winding 2, and the other end is connected to point M; one end of the voltage regulating switching mechanism 3 is connected to point M, and the other end is connected to point Q; one end of the voltage regulating switch K5 and the voltage regulating switch K9 is connected to the tap corresponding to the voltage regulating winding 2, and the other end is connected to point N; one end of the voltage regulating switching mechanism 2 is connected to point N, and the other end is connected to point Q.

[0051] P and Q are connected to form a conductive circuit.

[0052] The voltage regulating switching mechanism 1 is the same as the voltage regulating switching mechanism 2 , the voltage regulating switching mechanism 3 , and the voltage regulating switching mechanism 4 .

[0053] like Figure 2 As shown, each voltage regulating switching mechanism includes: an arc suppression switch K, an IGBT module G, and a transition resistor R.

[0054] Among them, the IGBT module G is connected in series with the transition resistor R to form a transition circuit during the switching process; the arc suppression switch K is the conduction circuit for the normal operation of the voltage regulating switching mechanism and is connected in parallel with the transition circuit.

[0055] The voltage regulation switching mechanism is divided into 4 states according to the conduction mode:

[0056] One is the disconnected state, at this time the arc extinguishing switch K and the IGBT module G are both disconnected, such as Figure 2 As shown;

[0057] The second is the normal working conduction state, at this time the arc extinguishing switch K is closed and the IGBT module G is disconnected, such as Figure 3 As shown;

[0058] The third is the conduction state during the switching process. At this time, the arc suppression switch K and the IGBT module G are both closed, forming a parallel conduction circuit, such as Figure 4 As shown;

[0059] The fourth is the transition process conduction state, at this time the arc extinguishing switch K is disconnected and the IGBT module G is closed, such as Figure 5 As shown;

[0060] Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 The black bold solid line in FIG represents the conduction circuit of the voltage regulating switching mechanism.

[0061] In this embodiment, the arc suppression switches K in all voltage regulation switching mechanisms adopt short-circuit-resistant magnetic latching relays; all voltage regulation switches (K2, K4, K6, K8, K3, K5, K7, K9) adopt short-circuit-resistant magnetic latching relays.

[0062] The selected short-circuit-resistant magnetic latching relays all have a manual disconnection function. When the distribution transformer device is undergoing a ratio test, the magnetic latching relay can be manually operated; when the controller has no power or is not working, manual operation of the magnetic latching relay can perform off-excitation voltage regulation, thereby realizing the coexistence of automatic on-load voltage regulation and off-excitation voltage regulation; when the controller is working normally, manual operation of the magnetic latching relay is not allowed.

[0063] In this embodiment, the transition resistor R is made of nickel-chromium alloy (Ni80Cr20) or iron-chromium-aluminum alloy (Cr25Al5) and adopts a skeleton spiral structure. The selected nickel-chromium alloy (Ni80Cr20) or iron-chromium-aluminum alloy (Cr25Al5) has high resistivity and high operating temperature.

[0064] The three-phase low-voltage winding adopts a star connection mode, and the neutral point is led out and grounded.

[0065] The three-phase high-voltage winding adopts a triangle or star connection mode, has no neutral point or the neutral point is not led out.

[0066] The voltage regulating winding adopts a single bridge cross-connection voltage regulating method.

[0067] The low voltage winding is equipped with a voltage measuring device and provides power to the controller.

[0068] The voltage measuring device directly measures the voltage value of the three-phase low-voltage winding without using a voltage transformer, and sends the voltage value to the controller. The voltage value includes: the phase-to-ground voltage value of the three-phase low-voltage winding and the line voltage value between the three-phase low-voltage windings.

[0069] The controller performs calculations based on the received voltage values ​​of the three-phase low-voltage windings and generates voltage regulation logic to control the opening and closing of the voltage regulating switches and the voltage regulating switching mechanisms in the adjustable winding components 1 and 2.

[0070] When controlling the operation of each voltage regulating switching mechanism, it is necessary to first operate the IGBT module G and then operate the arc suppression switch K. The operations include closing and opening.

[0071] The controller is connected to all voltage regulating switches (K2, K4, K6, K8, K3, K5, K7, K9) and voltage regulating switching mechanisms (1, 2, 3, 4) in the adjustable winding assembly 1 and the adjustable winding assembly 2, and is used to control the input and output of the voltage regulating windings in the adjustable winding assembly and the opening and closing of the voltage regulating switching mechanisms.

[0072] like Figure 6 As shown, the controller includes an isolated step-down unit, a power supply unit, a voltage sampling unit, a zero-crossing detection unit, a reset circuit, a single-chip microcomputer control unit, an IGBT trigger drive unit, and a control signal output unit. The input end of the isolated step-down unit is connected to the secondary side of the distribution transformer, the power supply unit, the voltage sampling unit, and the zero-crossing detection unit are connected between the output end of the isolated step-down unit and the input end of the single-chip microcomputer control unit, the reset circuit is connected to the single-chip microcomputer control unit, and the IGBT trigger drive unit and the control signal output unit are connected to the output end of the single-chip microcomputer control unit to send a voltage regulation trigger signal to the adjustable winding assembly.

[0073] The zero-crossing point and sampling voltage before voltage reduction are collected from the secondary side of the distribution transformer. After voltage reduction through the isolation step-down transformer, the voltage is passed through the voltage sampling unit and the zero-crossing detection unit and transmitted to the single-chip microcomputer control unit. The IGBT trigger drive unit and the control signal output unit send trigger signals to each IGBT module, arc suppression switch and voltage regulating switch in the adjustable winding assembly 1 and the adjustable winding assembly 2 according to the voltage regulation strategy of the single-chip microcomputer control unit, according to the predetermined logic and timing, to complete the voltage regulation action. The IGBT trigger drive unit has built-in undervoltage, overvoltage and short-circuit drive protection circuits and device fault detection circuits.

[0074] In this embodiment, the voltage regulation logic corresponding to the three-phase low-voltage winding voltage values ​​is determined by pre-calibration. During actual voltage regulation, the corresponding voltage regulation logic is invoked based on the three-phase low-voltage winding voltage values ​​to generate a voltage regulation strategy. This process is a conventional technical means in this field and will not be repeated here.

[0075] Example 2

[0076] This embodiment discloses a method for regulating the voltage of an automatic on-load voltage-regulating distribution transformer. This method is based on the distribution transformer described in Example 1. When the automatic on-load voltage-regulating distribution transformer is in normal working state:

[0077] Only one tap in the adjustable winding assembly 1 is connected to point P, that is, only one of the voltage regulating switches K2, K4, K6, and K8 is closed, and the rest are open; when the voltage regulating switch K8 or the voltage regulating switch K4 is closed, the voltage regulating switching mechanism 1 is in a normal working conduction state, and when the voltage regulating switch K6 or the voltage regulating switch K2 is closed, the voltage regulating switching mechanism 2 is in a normal working conduction state; only one of the voltage regulating switching mechanism 1 and the voltage regulating switching mechanism 2 is in a normal working conduction state, and the other is in a disconnected state.

[0078] Only one tap in the adjustable winding assembly 2 is connected to point Q, that is, only one of the voltage regulating switches K3, K5, K7, and K9 is closed, and the rest are open; when the voltage regulating switch K3 or the voltage regulating switch K7 is closed, the voltage regulating switching mechanism 3 is in a normal working conduction state, and when the voltage regulating switch K5 or the voltage regulating switch K9 is closed, the voltage regulating switching mechanism 4 is in a normal working conduction state; only one of the voltage regulating switching mechanism 3 and the voltage regulating switching mechanism 4 is in a normal working conduction state, and the other is in a disconnected state.

[0079] During the voltage regulation switching process, one of the adjustable winding assembly 1 and the adjustable winding assembly 2 can be operated, or both can be operated simultaneously. Operating the adjustable winding assembly 1 and the adjustable winding assembly 2 simultaneously can increase the range of a single voltage regulation.

[0080] The process of the voltage regulation method of the device of the present invention is as follows: Figure 7 As shown, the following steps are included:

[0081] S01) monitor the operating status of the distribution transformer in real time and detect the voltage value of the low-voltage winding through a voltage measuring device;

[0082] S02) Determine whether the voltage value of the low-voltage winding is qualified. If qualified, continue real-time monitoring. If unqualified, the controller calculates the voltage regulation strategy corresponding to the current low-voltage winding voltage and generates a voltage regulation logic control signal according to the voltage regulation strategy;

[0083] S03) Switch the adjustable winding components according to the voltage regulation logic control signal to complete the voltage regulation action.

[0084] The process of switching the adjustable winding components according to the voltage regulation logic control signal is:

[0085] S31), closing a voltage regulating switch connected to the voltage regulating switching mechanism in the disconnected state;

[0086] S32), closing the IGBT module in the normal working conduction state voltage regulating switching mechanism, so that the voltage regulating switching mechanism is in the switching process conduction state;

[0087] S33), disconnecting the arc-extinguishing switch in the voltage-regulating switching mechanism described in step S32, so that the voltage-regulating switching mechanism is in a transitional conductive state;

[0088] S34), closing the IGBT module in the voltage regulating switching mechanism in step S31, so that the voltage regulating switching mechanism is in a transition process conducting state;

[0089] S35), disconnecting the IGBT module in the voltage regulating switching mechanism in step S32, so that the voltage regulating switching mechanism is in an off state;

[0090] S36) disconnecting the voltage regulating switch in the original closed state;

[0091] S37), closing the arc suppression switch in the voltage regulating switching mechanism described in step S31, so that the voltage regulating switching mechanism is in a conducting state during the switching process;

[0092] S38) disconnecting the IGBT module of the voltage regulation switching mechanism in step S31, so that the voltage regulation switching mechanism is in a normal working state, completing the voltage regulation switching process.

[0093] For ease of description, the present invention takes the switching from the rated tap state (K5 and K6 are closed) to a certain tap state (K6 and K7 are closed) as an example to illustrate the steps of the voltage regulation switching process:

[0094] In the rated tap state, K5 and K6 are closed, and the other voltage regulating switches are disconnected. The voltage regulating switching mechanism 2 and the voltage regulating switching mechanism 4 connected thereto are in the normal working conduction state, and the voltage regulating switching mechanism 1 and the voltage regulating switching mechanism 3 are in the disconnected state. Figure 8 shown.

[0095] The first step is to close the voltage regulating switch K7. Figure 9 At this time, the voltage regulating switching mechanism 3 is still in the disconnected state, as shown Figure 2 shown.

[0096] In the second step, the IGBT module G in the voltage regulating switching mechanism 4 is closed, so that the voltage regulating switching mechanism 4 is in the conducting state during the switching process, such as Figure 4 shown.

[0097] The third step is to disconnect the arc extinguishing switch K in the voltage regulating switching mechanism 4, so that the voltage regulating switching mechanism 4 is in the transition process conduction state, such as Figure 5 shown.

[0098] The fourth step is to close the IGBT module G in the voltage regulating switching mechanism 3, so that the voltage regulating switching mechanism 3 is in the transition process conduction state, such as Figure 5 As shown; at this time, there are two parallel conductive circuits in the adjustable winding component 2, as shown Figure 10 shown.

[0099] Step 5: disconnect the IGBT module G in the voltage regulating switching mechanism 4. Figure 11 The voltage regulating switching mechanism 4 is in the off state, as shown; Figure 2 shown.

[0100] Step 6: Disconnect the voltage regulating switch K5.

[0101] The seventh step is to close the arc extinguishing switch K in the voltage regulating switching mechanism 3, so that the voltage regulating switching mechanism 3 is in the conducting state during the switching process, as shown in FIG. Figure 4 shown.

[0102] In the eighth step, the IGBT module G in the voltage regulating switching mechanism 3 is disconnected to put the voltage regulating switching mechanism 3 into a normal working state, such as Figure 2 As shown; the conduction circuit of the adjustable winding component part is as follows Figure 12 shown.

[0103] Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 The black bold solid line in represents the conduction circuit of the adjustable winding component portion.

[0104] During the voltage regulation switching process, the adjustable winding assembly 1 and the adjustable winding assembly 2 can be operated simultaneously, and the operation steps are similar. In the present invention, the two adjustable winding assemblies are independent of each other, and their respective voltage regulation switching mechanisms do not affect each other, which can ensure that there is no power outage during the switching process of simultaneous operation.

[0105] The present invention realizes rapid switching of the voltage regulating winding tapping head through the voltage regulating switch and the voltage regulating switching mechanism in the adjustable winding assembly 1 and the adjustable winding assembly 2. The switching speed is faster than that of a mechanical switch, and no arc is generated during the switching process, thereby improving the speed and efficiency of voltage regulation.

[0106] The transition circuit in the voltage regulating switching mechanism of the present invention adopts a method of connecting an IGBT module and a transition resistor in series, and can also adopt a method of connecting an IGBT module and a transition inductor in series. The transition resistor and the transition inductor have the same function, both of which limit the size of the circulating current generated by the transition circuit during the switching process.

[0107] In the present invention, the voltage regulating windings 1 and 2 lead to a total of eight tapping terminals, enabling seven levels of voltage regulation. The present invention can also increase or decrease the number of voltage regulating winding tapping terminals, and the number of voltage regulating switches connected thereto, depending on the actual voltage regulation level, while maintaining the same number of voltage regulating switching mechanisms. The circuit wiring method is consistent with the design concept described in the present invention, with one end of two adjacent voltage regulating switches connected to the corresponding voltage regulating winding tapping terminal and the other end connected to different voltage regulating switching mechanisms.

[0108] The present invention takes the voltage regulating winding leading out 8 taps to achieve 7-speed voltage regulation as an example, which is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the design concepts and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. An automatic on-load tap-changing distribution transformer, characterized in that: It has a three-phase winding, each phase winding includes a low-voltage winding, a high-voltage winding 1, a high-voltage winding 2, an adjustable winding assembly 1, an adjustable winding assembly 2 and a controller, the high-voltage winding 1, the adjustable winding assembly 1, the adjustable winding assembly 2, and the high-voltage winding 2 are connected in series in sequence to form a high-voltage winding, the low-voltage winding is coupled to the high-voltage winding, the controller receives the voltage signal of the low-voltage winding and is controlled and connected with the adjustable winding assembly 1 and the adjustable winding assembly 2; the adjustable winding assembly 1 includes a voltage-regulating winding 1 connected to the high-voltage winding 1, a plurality of voltage-regulating switches connected to the tapping end of the voltage-regulating winding 1, a voltage-regulating switching mechanism 1 and a voltage-regulating switching mechanism 2, one end of the plurality of voltage-regulating switches is connected to the corresponding tapping end of the voltage-regulating winding 1, and the other end is connected to the voltage-regulating switching mechanism 1 or the voltage-regulating switching mechanism 2 in a manner that two adjacent voltage-regulating switches are respectively connected to different voltage-regulating switching mechanisms, and the other ends of the voltage-regulating switching mechanism 1 and the voltage-regulating switching mechanism 2 are both connected to point P; The adjustable winding assembly 2 includes a voltage regulating winding 2 connected to the high-voltage winding 2, multiple voltage regulating switches connected to the tapping end of the voltage regulating winding 2, a voltage regulating switching mechanism 3 and a voltage regulating switching mechanism 4. One end of the multiple voltage regulating switches is connected to the corresponding tapping end of the voltage regulating winding 2, and the other end is connected to the voltage regulating switching mechanism 3 or the voltage regulating switching mechanism 4 in a manner that two adjacent voltage regulating switches are respectively connected to different voltage regulating switching mechanisms. The other ends of the voltage regulating switching mechanism 3 and the voltage regulating switching mechanism 4 are both connected to point Q; point P and point Q are connected to form a conductive circuit.

2. The automatic on-load tap-changing distribution transformer according to claim 1, characterized in that: The voltage regulating switching mechanism includes an arc extinguishing switch, an IGBT module and a transition device. The IGBT module and the transition device are connected in series to form a transition circuit during the switching process. The arc extinguishing switch is a conduction circuit for the normal operation of the voltage regulating switching mechanism and is connected in parallel with the transition circuit.

3. The automatic on-load tap-changing distribution transformer according to claim 1, characterized in that: The controller includes an isolation step-down unit, a power supply unit, a voltage sampling unit, a zero-crossing detection unit, a reset circuit, a single-chip microcomputer control unit, an IGBT trigger drive unit and a control signal output unit. The input end of the isolation step-down unit is connected to the secondary side of the distribution transformer, the power supply unit, the voltage sampling unit and the zero-crossing detection unit are connected between the output end of the isolation step-down unit and the input end of the single-chip microcomputer control unit, the reset circuit is connected to the single-chip microcomputer control unit, and the IGBT trigger drive unit and the control signal output unit are connected to the output end of the single-chip microcomputer control unit for sending a voltage regulation trigger signal to the adjustable winding assembly.

4. The automatic on-load tap-changing distribution transformer according to claim 2, characterized in that: The transition device is a transition resistor or a transition inductor.

5. The automatic on-load tap-changing distribution transformer according to claim 2, characterized in that: The voltage regulating switch and arc extinguishing switch both adopt short-circuit-resistant magnetic latching relays.

6. The automatic on-load tap-changing distribution transformer according to claim 1, characterized in that: The low-voltage winding is equipped with a voltage measuring device, which directly measures and sends the voltage value of the three-phase low-voltage winding to the controller. The voltage value includes the phase-to-ground voltage value of the three-phase low-voltage winding and the line voltage value between the three-phase low-voltage windings.

7. The automatic on-load tap-changing distribution transformer according to claim 1, characterized in that: The three-phase low-voltage winding adopts a star connection mode, with a neutral point led out and grounded; the three-phase high-voltage winding adopts a triangle or star connection mode, with no neutral point or the neutral point is not led out, and the voltage regulating winding adopts a single-bridge jumper voltage regulation mode.

8. A method for regulating voltage of an automatic on-load voltage-regulating distribution transformer, the method being implemented based on the automatic on-load voltage-regulating distribution transformer according to any one of claims 1 to 7, characterized in that: The following steps are involved: S01) monitor the operating status of the distribution transformer in real time and detect the voltage value of the low-voltage winding through a voltage measuring device; S02) Determine whether the voltage value of the low-voltage winding is qualified. If qualified, continue real-time monitoring. If unqualified, the controller calculates the voltage regulation strategy corresponding to the current low-voltage winding voltage and generates a voltage regulation logic control signal according to the voltage regulation strategy; S03) Switch the adjustable winding components according to the voltage regulation logic control signal to complete the voltage regulation action.

9. The method for regulating voltage of an automatic on-load voltage regulating distribution transformer according to claim 8, characterized in that: The process of switching the adjustable winding components according to the voltage regulation logic control signal is: S31), closing a voltage regulating switch connected to the voltage regulating switching mechanism in the disconnected state; S32), closing the IGBT module in the normal working conduction state voltage regulating switching mechanism, so that the voltage regulating switching mechanism is in the switching process conduction state; S33), disconnecting the arc-extinguishing switch in the voltage-regulating switching mechanism described in step S32, so that the voltage-regulating switching mechanism is in a transitional conductive state; S34), closing the IGBT module in the voltage regulating switching mechanism in step S31, so that the voltage regulating switching mechanism is in a transition process conducting state; S35), disconnecting the IGBT module in the voltage regulating switching mechanism in step S32, so that the voltage regulating switching mechanism is in an off state; S36) disconnecting the voltage regulating switch in the original closed state; S37), closing the arc suppression switch in the voltage regulating switching mechanism described in step S31, so that the voltage regulating switching mechanism is in a conducting state during the switching process; S38) disconnecting the IGBT module of the voltage regulation switching mechanism in step S31, so that the voltage regulation switching mechanism is in a normal working state, completing the voltage regulation switching process.

10. The method for regulating voltage of an automatic on-load voltage regulating distribution transformer according to claim 8, characterized in that: According to the voltage regulation logic control signal, a single or multiple adjustable winding components are switched. Multiple adjustable winding components are operated individually or simultaneously. When controlling the action of each voltage regulation switching mechanism, the IGBT module must be operated first, and then the arc suppression switch is operated. The operations include closing and opening.

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