Boost type active area transformer

Abstract

The invention provides a boost type active area transformer, and relates to the technical field of transformers. The boost type active area transformer comprises a distribution transformer, a capacitor and an AC / AC converter, and the AC / AC converter comprises two bridge arms and an inductor. Wherein the two bridge arms are connected with a plurality of control ends and are suitable for being switched off or switched on under the control of control signals accessed to the control ends, the change of the states of the bridge arms promotes the capacitor and the inductor to charge or discharge, and the voltage at the output end is larger than the voltage at the secondary side of the distribution transformer through the discharge of the capacitor or the inductor. And a corresponding voltage value is provided for a device connected with the output end. The boost type active area transformer is a hybrid distribution transformer, the circuit structure of the transformer is simple, control is easy to achieve, a primary framework is adopted, under the condition that voltage treatment is achieved, the number of devices is reduced, efficiency is improved, the size is reduced, and meanwhile cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of transformers, and particularly to a step-up active substation transformer. Background Art

[0002] With the rapid economic development and the increasing access of new energy sources such as photovoltaic power, the problem of voltage over-limit in the distribution network (voltage higher than the specified voltage value and voltage lower than the specified voltage) is significant. The traditional method of using a single distribution transformer to control the voltage over-limit problem has limitations such as slow operation speed, arc generation, low efficiency, large volume, low adjustment accuracy, and inability to smoothly adjust the voltage. Therefore, there is an urgent need for technological innovation to meet the development needs of the new power system.

[0003] The hybrid distribution transformer voltage regulation technology has emerged as a new voltage regulation solution. It has significant advantages such as fast response speed, diverse functions, and flexible voltage regulation methods. The hybrid distribution transformer optimizes the traditional voltage regulation mode by integrating the power electronic voltage regulator with the distribution transformer. Currently, its main technical principle is as Figure 1 shown. In the hybrid distribution transformer, the power electronic circuit uses a unified power quality conditioner (UPQC), which is composed of two three-phase full-bridge circuits, and is connected in series and parallel with the output terminal of the distribution transformer respectively. The parallel part (CV t ) can essentially be regarded as a three-phase fully controlled rectifier circuit, which is connected to the low-voltage auxiliary winding (W 3a , W 3b , W 3c ) of the distribution transformer. This connection method enables it to achieve key functions such as power factor control, harmonic suppression, and DC bus voltage control. The series part (CV p ) is connected in series with the high-voltage side of the distribution transformer through the power frequency voltage regulating transformer windings (W 5a , W 5b , W 5c ). By using the PWM modulation technology, the series voltage is precisely controlled to achieve flexible adjustment of the output voltage.

[0004] However, although the hybrid distribution transformer shows many advantages, the existing UPQC device (UPQC) in the hybrid distribution transformer adopts a two-stage structure design of rectification first and then inversion, resulting in low efficiency. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] Aiming at the deficiencies of the prior art, the present invention provides a step-up active substation transformer, which solves the problem of low efficiency of the existing hybrid distribution transformer.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the present invention is realized by the following technical solutions:

[0009] In a first aspect, the present invention provides a boost-type active substation transformer, including a distribution transformer, a capacitor, and an AC / AC converter. Among them, the AC / AC converter includes two bridge arms and an inductor; the primary side of the distribution transformer is connected to an AC source, the first connection end of the secondary side is connected to the first output end via a capacitor, the second connection end of the secondary side is connected to the second output end through a wire, and a connection port a is provided on the wire;

[0010] The first end of the first bridge arm of the AC / AC converter is connected to the common end of the capacitor and the first output end, and the second end is connected to the connection port a via the second bridge arm;

[0011] The first end of the inductor is connected to the common end of the capacitor and the secondary side of the distribution transformer, and the second end is connected to the common end of the first bridge arm and the second bridge arm;

[0012] The two bridge arms are connected with a plurality of control ends, and are adapted to be disconnected or conducted under the control of a control signal input at the control end. The change of the bridge arm state causes the capacitor and the inductor to be charged or discharged. Through the discharge of the capacitor or the inductor, the voltage at the output end is made greater than the voltage at the secondary side of the distribution transformer, so as to provide a suitable voltage value for the device connected to the output end.

[0013] Preferably, when the voltage at the output end is increased by discharging the inductor, the working modes of the boost-type active substation transformer include:

[0014] Working mode 1: The first bridge arm is conducted, the second bridge arm is disconnected, and the current flow path is the secondary side of the distribution transformer → inductor → first bridge arm → the device connected to the output end and inductor → first bridge arm → capacitor. At this time, the secondary side of the distribution transformer and the inductor release energy to supply power to the device connected to the output end and charge the capacitor.

[0015] Preferably, when the voltage at the output end is increased by discharging the capacitor, the working modes of the boost-type active substation transformer include:

[0016] Working mode 2: The second bridge arm is conducted, the first bridge arm is disconnected, and the current flow path is the secondary side of the distribution transformer → inductor → second bridge arm and the secondary side of the distribution transformer → capacitor → the device connected to the output end. At this time, the secondary side of the distribution transformer charges and stores energy in the inductor, and the secondary side of the distribution transformer and the capacitor supply power to the device connected to the output end.

[0017] Preferably, it further includes a bypass switch, both ends of the bypass switch are respectively connected to both ends of the capacitor. When the AC source voltage is normal, the voltage on the secondary side of the distribution transformer is equal to the voltage required by the device connected to the output terminal. After closing the bypass switch and disconnecting the two arms of the AC / AC converter, the AC / AC converter is removed.

[0018] Preferably, each of the two arms includes a connected antipodal switch group, and the two arms are disconnected or conducted by controlling the turn-off or turn-on of the antipodal switch group.

[0019] Preferably, each of the two arms includes a double-control switch, and the double-control switch includes a first diode, a second diode, a third diode, a fourth diode and a switch tube.

[0020] Wherein, the anode of the first diode is connected to the cathode of the second diode, and their common end serves as the first connection end of the arm.

[0021] The cathode of the first diode is connected to the cathode of the third diode, and their common end is connected to the first end of the switch tube.

[0022] Wherein, the anode of the third diode is connected to the cathode of the fourth diode, and their common end serves as the second connection end of the arm.

[0023] The anode of the fourth diode is connected to the anode of the second diode, and their common end is connected to the second end of the switch tube.

[0024] Preferably, the device connected to the output terminal includes a power distribution network or a load.

[0025] In a second aspect, the present invention provides a boost-type active substation transformer applied in a three-phase system, including three boost-type active substation transformers as described above.

[0026] Wherein, the primary sides of the distribution transformers in the three boost-type active substation transformers are connected to a three-phase AC power supply; the first connection end of the primary side of the distribution transformer of the first boost-type active substation transformer and the second connection end of the primary side of the distribution transformer of the third boost-type active substation transformer are connected together and commonly connected to phase A; the second connection end of the primary side of the distribution transformer of the first boost-type active substation transformer and the first connection end of the primary side of the distribution transformer of the second boost-type active substation transformer are connected together and commonly connected to phase B; the second connection end of the primary side of the distribution transformer of the second boost-type active substation transformer and the first connection end of the primary side of the distribution transformer of the third boost-type active substation transformer are connected together and commonly connected to phase C;

[0027] The second connection ends of the secondary sides of the three distribution transformers are connected together.

[0028] In a third aspect, the present invention provides a step-up active substation transformer applied in a three-phase system, including three step-up active substation transformers;

[0029] Wherein, each step-up active substation transformer includes a distribution transformer, a capacitor and an AC / AC converter, and the AC / AC converter includes two bridge arms and an inductor;

[0030] Wherein, the first connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the second connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and commonly connected to phase A; the second connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the second step-up active substation transformer are connected together and commonly connected to phase B; the second connection end of the primary side of the distribution transformer of the second step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and commonly connected to phase C;

[0031] The first connection end of the secondary side of each distribution transformer is connected to the output end via a capacitor; and the second connection ends of the secondary sides of the three distribution transformers are connected together;

[0032] The first end of the first bridge arm of the AC / AC converter is connected to the common end of the capacitor and the first output end, and the second end is connected to the second connection end of the secondary side of the distribution transformer via the second bridge arm;

[0033] The first end of the inductor is connected to the common end of the capacitor and the secondary side of the distribution transformer, and the second end is connected to the common end of the first bridge arm and the second bridge arm;

[0034] Wherein, the output ends of the three step-up active substation transformers are respectively connected to the first ends of the distribution network or the load, and the second ends of the distribution network or the load are connected together;

[0035] The two bridge arms are connected with a plurality of control ends, and are adapted to be turned off or on under the control of a control signal input to the control ends. The change of the bridge arm state causes the capacitor and the inductor to be charged or discharged. By discharging the capacitor or the inductor, the voltage at the output end is made greater than the voltage of the secondary side of the distribution transformer, so as to provide a suitable voltage value for the device connected to the output end.

[0036] Preferably, each of the two bridge arms includes a pair of opposite switch groups, and the two bridge arms are turned off or on by turning off or on the pair of opposite switch groups;

[0037] Or,

[0038] Both of the two bridge arms include a dual-control switch, and the dual-control switch includes a first diode, a second diode, a third diode, a fourth diode and a switching tube.

[0039] Among them, the anode of the first diode is connected to the cathode of the second diode, and their common end serves as the first connection end of the bridge arm.

[0040] The cathode of the first diode is connected to the cathode of the third diode, and their common end is connected to the first end of the switching tube.

[0041] Among them, the anode of the third diode is connected to the cathode of the fourth diode, and their common end serves as the second connection end of the bridge arm.

[0042] The anode of the fourth diode is connected to the anode of the second diode, and their common end is connected to the second end of the switching tube.

[0043] (III) Beneficial effects

[0044] The present invention provides a boost-type active substation area transformer. Compared with the prior art, the following beneficial effects are achieved:

[0045] Compared with traditional equipment such as UPQC, the boost-type active substation area transformer proposed by the present invention is a hybrid distribution transformer. The circuit structure of this transformer is simple, and the control is easy to implement. It adopts a first-level architecture. While achieving voltage governance, the number of devices is saved, and the cost is greatly reduced while improving efficiency and reducing volume. Description of the drawings

[0046] 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 required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0047] Figure 1 It is the circuit diagram of the existing hybrid distribution transformer;

[0048] Figure 2 It is the architecture diagram of a boost-type active substation area transformer in Embodiment 1;

[0049] Figure 3 It is for Figure 2 The first specific circuit diagram of the architecture diagram;

[0050] Figure 4 It is for Figure 3 The state diagram of the switching tube when the circuit shown is in operating mode 1;

[0051] Figure 5 It is forFigure 3 The state diagram of the switching transistor when the shown circuit is in operating mode 2;

[0052] Figure 6 is Figure 2 The second specific circuit diagram of the architecture diagram of

[0053] Figure 7 The architecture diagram of a boost-type active substation area transformer in Embodiment 2;

[0054] Figure 8 The architecture diagram of applying the boost-type active substation area transformer in a three-phase system in Embodiment 3, and its connection method is the star connection method;

[0055] Figure 9 The architecture diagram of applying the boost-type active substation area transformer in a three-phase system in Embodiment 3, and its connection method is the delta connection method. Specific implementation manners

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0057] It should be noted that for the convenience of narration, the switching IGBT is used to represent the controllable (conducting and turning off) switching transistor in the embodiments of the present invention, but the switching transistor in the present invention is not limited to IGBT. Taking IGBT as an example for illustration. The first end of the IGBT refers to the collector, the second end refers to the emitter, and the control end refers to the gate. A drive control signal is applied to the control end of each switching transistor in the embodiments of the present invention. For the sake of simplicity, it will not be elaborated later. The power switching transistor in the embodiments of the present invention can also be implemented by other controllable switching transistor devices other than IGBT, such as MOSFET. At the same time, in the embodiments of the present invention, to ensure the normal operation of each switching device, a freewheeling diode needs to be connected in parallel with each switching device. The parallel connection direction of the freewheeling diode is related to the type of the switching device, and those skilled in the art can set it according to the type of the switching device, which is not limited herein. If not specified, the switching device is default to include a freewheeling diode, and this embodiment will point it out in special cases.

[0058] By providing a boost-type active substation area transformer in the embodiments of the present application, the technical problem of low efficiency of some hybrid distribution transformers is solved. The AC / AC conversion is realized by using a single-stage energy conversion, replacing the mainstream AC / DC + DC / AC two-stage architecture, and achieving high efficiency and low cost.

[0059] The technical solutions in the embodiments of the present application for solving the above technical problems have the following general idea:

[0060] By integrating a power electronic voltage regulator and a distribution transformer, the hybrid distribution transformer optimizes the traditional voltage regulation mode and has significant advantages such as fast response speed, diverse functions, and flexible voltage regulation methods. However, the UPQC device (UPQC) in the existing hybrid distribution transformer adopts a two-stage structure design of rectification first and then inversion, which inevitably brings a series of problems. From the control perspective, the two-stage structure makes the control logic intricate, greatly increasing the operation and maintenance difficulty and technical threshold of the system; during operation, the two-stage energy conversion leads to a reduction in the operating efficiency of the transformer; moreover, the large number of power electronic devices required by the two-stage structure significantly increases the volume of the equipment, not only occupying more installation space but also further increasing the equipment cost. In addition, the required power frequency voltage regulating transformer and DC bus capacitor in the existing hybrid distribution transformer are bulky, and an auxiliary winding needs to be added on the low-voltage side, changing the original structure of the distribution transformer, so the cost is still much higher than that of the traditional mechanical on-load tap-changing distribution transformer. These defects seriously restrict the popularization and application of hybrid distribution transformers in a wider range of scenarios.

[0061] To solve the above problems, the embodiments of the present invention propose a boost-type active substation area transformer that combines a traditional on-load tap-changing transformer and a power electronic transformer. It adopts a single-stage energy conversion to achieve AC / AC conversion, replacing the mainstream AC / DC + DC / AC two-stage architecture, achieving high efficiency and low cost. At the same time, there is a bridging capacitor in the topology of the boost-type active substation area transformer of the embodiments of the present invention. Because the voltage of the capacitor cannot change suddenly, the modulation technology of high-frequency power switching tubes can be used to control the smooth change of the capacitor voltage. Finally, the voltage on the capacitor is superimposed on the input voltage, which can effectively ensure the smoothness of the AC output, and the standard AC voltage output is realized by using control technology, and the waveform quality is good.

[0062] To better understand the above technical solutions, the above technical solutions will be described in detail below in conjunction with the accompanying drawings of the specification and specific implementation manners.

[0063] Embodiment 1:

[0064] This embodiment provides a boost-type active substation area transformer, as Figure 2 shown, including a distribution transformer, a capacitor, and an AC / AC converter. Among them, the AC / AC converter includes two bridge arms and an inductor; the primary side of the distribution transformer is connected to an AC source, the first connection end of the secondary side is connected to the first output terminal O1 via a capacitor, and the second connection end of the secondary side is connected to the second output terminal O2 through a wire (in the specific implementation process, the two output terminals are connected to the distribution network or load. In Figure 2In the case where two output terminals are connected to both sides of the load, a connection port a is set on the wire; the first end of the first arm of the AC / AC converter is connected to the common end of the capacitor and the first output terminal, and the second end is connected to the connection port a via the second arm; the first end of the inductor is connected to the common end of the capacitor and the secondary side of the distribution transformer, and the second end is connected to the common end of the first arm and the second arm;

[0065] The two arms are connected with a number of control terminals and are adapted to be disconnected or conducted under the control of a control signal applied to the control terminals. The change of the arm state causes the capacitor and the inductor to be charged or discharged. By discharging the capacitor or the inductor, the voltage at the output terminal is made greater than the voltage on the secondary side of the distribution transformer to a voltage value that meets the output requirements.

[0066] During the implementation process, when the voltage on the secondary side of the distribution transformer is less than the voltage required by the power distribution network or the load, the circuit can operate to boost the voltage at the output terminal and stabilize the voltage at the output terminal. The circuit has two operating modes:

[0067] Operating mode 1: The first arm is conducted and the second arm is disconnected. The current flow path is the secondary side of the distribution transformer → inductor → first arm → load and inductor → first arm → capacitor. At this time, the secondary side of the distribution transformer and the inductor release energy to supply power to the load and charge the capacitor.

[0068] Operating mode 2: The second arm is conducted and the first arm is disconnected. The current flow path is the secondary side of the distribution transformer → inductor → second arm and the secondary side of the distribution transformer → capacitor → load. At this time, the secondary side of the distribution transformer charges the inductor to store energy, and the secondary side of the distribution transformer and the capacitor supply power to the load.

[0069] It should be noted that the function of this capacitor is different in the boost mode and the buck mode. In the boost mode, not only harmonic current but also main power current flows through the capacitor. In working state 1, both the secondary side and the inductor charge the capacitor and supply power to the load. In working state 2, the secondary side charges the inductor, and at the same time, the secondary side and the capacitor supply power to the load.

[0070] In the specific implementation process, the AC / AC converter includes two arms, and both can adopt two opposite switching tubes, as Figure 3 shown. The first switching tube T1 and the second switching tube T2 form the first arm, and the third switching tube T3 and the fourth switching tube T4 form the second arm. The AC / AC converter has a total of three operating modes. The states of the switching tubes in each mode are as Figure 4 、 5 shown.

[0071] Operating mode 1: As Figure 4As shown, switch tubes T1 and T2 are turned on, and other switch tubes are turned off. The current flow path is the secondary side of the distribution transformer → L → T1 → T2 → load and L → T1 → T2 → C. At this time, the inductor releases energy to supply power to the load and charges the capacitor.

[0072] Operating mode 2: As Figure 5 shown, switch tubes T3 and T4 are turned on, and other switch tubes are turned off. The current flow paths are the secondary side of the distribution transformer → L → T3 → T4 and the secondary side of the distribution transformer → C → load. At this time, the secondary side of the distribution transformer charges the inductor to store energy, and the secondary side of the distribution transformer and the capacitor supply power to the load.

[0073] In the specific implementation process, the bridge arm included in the AC / AC converter can also adopt a dual-control switch composed of four diodes and one switch tube, as Figure 6 shown. It should be noted that when constructing the two bridge arms of the AC / AC converter, it is not limited to the above two specific switch component designs. Multiple other switches can also be used to achieve the conduction and turn-off of the bridge arm, as long as these switches meet the following requirements: when the switch is in the off state, during the negative half cycle of the AC source connected to the primary side of the distribution transformer, the phenomenon of direct connection of the bridge arm must be avoided. At the same time, multiple switches can also be mixed and combined. For example, the first bridge arm adopts an opposite switch group, and the second bridge arm adopts a dual-control switch composed of four diodes and one switch tube.

[0074] Figure 6 The circuit operating mode shown in Figure 3 is the same as the operating mode of the circuit shown, and will not be elaborated here.

[0075] Embodiment 2:

[0076] This embodiment provides a boost-type active distribution transformer, as Figure 7 shown. This transformer adds a bypass switch on the basis of the circuit shown in Figure 2 . When the voltage of the AC source (power grid) is normal, the voltage on the secondary side of the distribution transformer is equal to the voltage required by the device (distribution network or load) connected to the output end. Then, it is not necessary for the AC / AC converter to boost the voltage at the output end, and this AC / AC converter needs to be removed to avoid unnecessary losses. Therefore, a bypass switch needs to be connected in parallel with the capacitor on the basis of the above circuit.

[0077] After closing the bypass switch, all the two bridge arms of the AC / AC converter are turned off, and then this AC / AC converter can be removed from the grid side.

[0078] The circuit form of the AC / AC converter in this embodiment is the same as that in Embodiment 1, and will not be elaborated here.

[0079] Embodiment 3:

[0080] In this embodiment, the boost-type active substation area transformer in Embodiment 1 or Embodiment 2 can be applied to a three-phase system, and its connection modes include a star connection mode and a delta connection mode. The star connection mode is as follows Figure 8 shown. The primary sides of the distribution transformers in the three boost-type active substation area transformers are connected to a three-phase AC power supply. Among them, the first connection end of the primary side of the distribution transformer of the first boost-type active substation area transformer and the second connection end of the primary side of the distribution transformer of the third boost-type active substation area transformer are connected together and commonly connected to phase A; the second connection end of the primary side of the distribution transformer of the first boost-type active substation area transformer and the first connection end of the primary side of the distribution transformer of the second boost-type active substation area transformer are connected together and commonly connected to phase B; the second connection end of the primary side of the distribution transformer of the second boost-type active substation area transformer and the first connection end of the primary side of the distribution transformer of the third boost-type active substation area transformer are connected together and commonly connected to phase C. The second connection ends of the secondary sides of the three distribution transformers are connected together, and the connection modes of other devices in the circuit topology of the boost-type active substation area transformer are the same as those in Embodiment 1, which will not be elaborated here.

[0081] The delta connection mode is as follows Figure 9 shown. The primary sides of the distribution transformers in the three boost-type active substation area transformers are connected to a three-phase AC power supply. Among them, the first connection end of the primary side of the distribution transformer of the first boost-type active substation area transformer and the second connection end of the primary side of the distribution transformer of the third boost-type active substation area transformer are connected together and commonly connected to phase A; the second connection end of the primary side of the distribution transformer of the first boost-type active substation area transformer and the first connection end of the primary side of the distribution transformer of the second boost-type active substation area transformer are connected together and commonly connected to phase B; the second connection end of the primary side of the distribution transformer of the second boost-type active substation area transformer and the first connection end of the primary side of the distribution transformer of the third boost-type active substation area transformer are connected together and commonly connected to phase C. The second connection ends of the secondary sides of the three distribution transformers are connected together. The connection modes of the two output ends of the three boost-type active substation area transformers with the load or the power grid are different from those of the boost-type active substation area transformer connected in a single-phase circuit with the load or the power grid. In the delta connection mode, the first output ends of the boost-type active substation area transformers are respectively connected to the load or the power grid and then connected together. After the wires led out from the second connection ends of the secondary sides of the three distribution transformers are connected to the second bridge arm, no wires are led out as the second output end.

[0082] It should be noted that, for the purpose of drawing, Figure 9 and Figure 8 the AC / AC converters in the boost-type active substation area transformers adopt a simplified drawing method.

[0083] In summary, compared with the prior art, the following beneficial effects are achieved:

[0084] 1. Compared with traditional equipment such as UPQC, the step-up active substation transformer proposed in the embodiments of the present invention is a hybrid distribution transformer. The circuit structure of this transformer is simple and the control is easy to implement. It adopts a first-level architecture. While achieving voltage regulation, the number of components is saved, and the cost is greatly reduced while improving efficiency and reducing volume.

[0085] 2. There is a bridging capacitor (i.e., capacitor C) in the topology of the step-up active substation transformer in the embodiments of the present invention. Since the voltage of the capacitor cannot change abruptly, the modulation technology of the high-frequency power switch tube can be used to control the smooth change of the capacitor voltage. Finally, the voltage on the capacitor is superimposed on the input voltage, which can effectively ensure the smoothness of the AC output. The standard AC voltage output is achieved by using control technology, and the waveform quality is good.

[0086] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0087] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A boost-type active substation transformer, characterized in that, It includes a distribution transformer, a capacitor and an AC / AC converter. The AC / AC converter includes two bridge arms and an inductor. The primary side of the distribution transformer is connected to an AC source. The first connection end of the secondary side is connected to the first output terminal via the capacitor. The second connection end of the secondary side is connected to the second output terminal through a wire, and a connection port a is arranged on the wire. The first end of the first bridge arm of the AC / AC converter is connected to the common end of the capacitor and the first output terminal, and the second end is connected to the connection port a via the second bridge arm. The first end of the inductor is connected to the common end of the capacitor and the secondary side of the distribution transformer, and the second end is connected to the common end of the first bridge arm and the second bridge arm. The two bridge arms are connected with a plurality of control terminals and are adapted to be turned off or on under the control of a control signal applied to the control terminals. The change of the bridge arm state causes the capacitor and the inductor to be charged or discharged. By discharging the capacitor or the inductor, the voltage at the output terminal is made greater than the voltage at the secondary side of the distribution transformer, so as to provide a suitable voltage value for the device connected to the output terminal.

2. The step-up active district transformer according to claim 1, characterized in that When the voltage at the output terminal is increased by discharging the inductor, the operating modes of the boost active substation area transformer include: Operating mode 1: The first bridge arm is turned on and the second bridge arm is turned off. The current flow path is the secondary side of the distribution transformer → inductor → first bridge arm → the device connected to the output terminal and inductor → first bridge arm → capacitor. At this time, the secondary side of the distribution transformer and the inductor release energy to supply power to the device connected to the output terminal and charge the capacitor.

3. The step-up active area transformer according to claim 1, characterized in that, When the voltage at the output terminal is increased by discharging the capacitor, the operating modes of the boost active substation area transformer include: Operating mode 2: The second bridge arm is turned on and the first bridge arm is turned off. The current flow path is the secondary side of the distribution transformer → inductor → second bridge arm and the secondary side of the distribution transformer → capacitor → the device connected to the output terminal. At this time, the secondary side of the distribution transformer charges the inductor for energy storage, and the secondary side of the distribution transformer and the capacitor supply power to the device connected to the output terminal.

4. The step-up active substation transformer according to any one of claims 1 to 3, characterized in that, It further includes a bypass switch. The two ends of the bypass switch are respectively connected to the two ends of the capacitor. When the voltage of the AC source is normal, the voltage at the secondary side of the distribution transformer is equal to the voltage required by the device connected to the output terminal. After closing the bypass switch and disconnecting the two bridge arms of the AC / AC converter, the AC / AC converter is cut off.

5. The step-up active substation transformer according to any one of claims 1 to 3, characterized in that Each of the two bridge arms includes a pair of opposed switch groups, and the turning off or on of the pair of opposed switch groups controls the turning off or on of the two bridge arms.

6. The step-up active substation transformer according to any one of claims 1 to 3, characterized in that, Each of the two bridge arms includes a double-control switch. The double-control switch includes a first diode, a second diode, a third diode, a fourth diode and a switch tube. Wherein, the anode of the first diode is connected to the cathode of the second diode, and their common end serves as the first connection end of the bridge arm. The cathode of the first diode is connected to the cathode of the third diode, and their common end is connected to the first end of the switch tube. Wherein, the anode of the third diode is connected to the cathode of the fourth diode, and their common end serves as the second connection end of the bridge arm. The anode of the fourth diode is connected to the anode of the second diode, and their common end is connected to the second end of the switch tube.

7. The step-up active substation transformer according to any one of claims 1 to 3, characterized in that, The device connected to the output terminal includes a power distribution network or a load.

8. A step-up active distribution transformer applied in a three-phase system, characterized in that, It includes three step-up active substation transformers as described in any one of claims 1 to 7; Among them, the primary sides of the distribution transformers in the three step-up active substation transformers are connected to a three-phase AC power supply; the first connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the second connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and jointly connected to phase A; the second connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the second step-up active substation transformer are connected together and jointly connected to phase B; the second connection end of the primary side of the distribution transformer of the second step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and jointly connected to phase C; The second connection ends of the secondary sides of the three distribution transformers are connected together.

9. A boost-type active substation transformer applied in a three-phase system, characterized in that, It includes three step-up active substation transformers; Among them, each step-up active substation transformer includes a distribution transformer, a capacitor, and an AC / AC converter, and the AC / AC converter includes two bridge arms and an inductor; Among them, the first connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the second connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and jointly connected to phase A; the second connection end of the primary side of the distribution transformer of the first step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the second step-up active substation transformer are connected together and jointly connected to phase B; the second connection end of the primary side of the distribution transformer of the second step-up active substation transformer and the first connection end of the primary side of the distribution transformer of the third step-up active substation transformer are connected together and jointly connected to phase C; The first connection end of the secondary side of each distribution transformer is connected to the output end via a capacitor; and the second connection ends of the secondary sides of the three distribution transformers are connected together; The first end of the first bridge arm of the AC / AC converter is connected to the common end of the capacitor and the first output end, and the second end is connected to the second connection end of the secondary side of the distribution transformer via the second bridge arm; The first end of the inductor is connected to the common end of the capacitor and the secondary side of the distribution transformer, and the second end is connected to the common end of the first bridge arm and the second bridge arm; Among them, the output ends of the three step-up active substation transformers are respectively connected to the first end of the distribution network or the load, and the second ends of the distribution network or the load are connected together; The two bridge arms are connected with a plurality of control ends, and are adapted to be turned off or on under the control of a control signal input to the control ends. The change of the bridge arm state causes the capacitor and the inductor to be charged or discharged. Through the discharge of the capacitor or the inductor, the output end voltage is made greater than the secondary side voltage of the distribution transformer, so as to provide a compliant voltage value for the device connected to the output end.

10. The step-up active distribution transformer applied to a three-phase system as described in claim 9, characterized in that, Each of the two bridge arms includes a connected antipodal switch group, and the two bridge arms are turned off or on by the turn-off or turn-on of the antipodal switch group; Or, Both of the two bridge arms include a double-control switch, and the double-control switch includes a first diode, a second diode, a third diode, a fourth diode and a switching tube. Wherein, the anode of the first diode is connected to the cathode of the second diode, and their common terminal serves as the first connection terminal of the bridge arm. The cathode of the first diode is connected to the cathode of the third diode, and their common terminal is connected to the first end of the switching tube. Wherein, the anode of the third diode is connected to the cathode of the fourth diode, and their common terminal serves as the second connection terminal of the bridge arm. The anode of the fourth diode is connected to the anode of the second diode, and their common terminal is connected to the second end of the switching tube.

Images