Hybrid voltage conversion device and control method thereof

Abstract

A hybrid transformer device and a control method thereof are disclosed. The hybrid transformer device includes a distribution transformer and at least one power electronic module. The normal operation mode and the bypass mode of the hybrid transformer device are switched by first and second hybrid switching switches of a series converter of the power electronic module. When the first and second hybrid switching switches switch the hybrid transformer device from the bypass mode to the normal operation mode, the first to fourth switching switches and the first to second hybrid switching switches are pulse width modulated. When the first and second hybrid switching switches switch the hybrid transformer device from the normal operation mode to the bypass mode, the first to fourth switching switches are stopped to maintain the off state, and the first to second hybrid switching switches are maintained or switched to the on state.

Description

Technical Field

[0001] This invention relates to a transformer and its control technology, and particularly to a hybrid transformer and its control method. Background Technology

[0002] When traditional renewable energy sources (such as solar power) constitute a large proportion of the total energy mix, it can often lead to the power grid (transmission network), which consists of power plants, substations, transmission systems, and distribution systems, exceeding its load capacity. To avoid grid congestion or renewable energy bottlenecks, solar systems (such as residential or industrial solar systems) need to stop transmitting power to the grid or even be temporarily shut down; this is known as renewable energy curtailment. Furthermore, as electric vehicles become increasingly prevalent, they consume significantly more electricity, potentially causing severe voltage drops in feeders in certain areas.

[0003] Furthermore, with the increasing proportion of renewable energy and the growing prevalence of electric vehicles, the power supply quality at the feeder end of the power grid will face significant challenges. Congestion in the power grid or renewable energy sources can easily lead to power cuts or curtailment. Simultaneously, when the load or electricity consumption is excessive, the voltage provided by the distribution transformer or feeder may fall below the lower limit or exceed the upper limit, making it difficult for the distribution transformer or feeder to provide a stable voltage to the load, and easily causing power outages, power shortages, or voltage instability.

[0004] Furthermore, existing technologies cannot utilize the first to second hybrid switching switches of the series converter to switch between the normal operation mode and the bypass mode of the hybrid transformer, nor can they reduce the switching losses or switching losses of the first to fourth switching switches and the first to second hybrid switching switches, nor can they improve the overall efficiency of the hybrid transformer.

[0005] Therefore, how to provide an innovative transformer device and its control technology to solve any of the above problems or provide related functions / methods and considerations for power electronic modules with replaceable / hot-swappable designs has become a major research topic for those skilled in the art. Summary of the Invention

[0006] The hybrid transformer device of the present invention includes: a distribution transformer having a high-voltage side and a low-voltage side opposite to each other; and at least one power electronic module having a parallel converter and a series converter electrically connected to each other. The parallel converter is electrically connected to the low-voltage side of the distribution transformer. The series converter has a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a first hybrid switching switch, and a second hybrid switching switch. The first hybrid switching switch of the series converter is electrically connected to the second hybrid switching switch and the first switching switch to the second switching switch, and the second hybrid switching switch of the series converter is electrically connected to the third switching switch to the fourth switching switch. The first hybrid switching switch of the series converter and... The second hybrid switching switch can switch between the normal operation mode and the bypass mode of the hybrid transformer. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the bypass mode to the normal operation mode, the first to fourth switching switches and the first hybrid switching switch to the second hybrid switching switch of the series converter are switched by pulse width modulation. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the normal operation mode to the bypass mode, the first to fourth switching switches of the series converter are stopped to remain in the closed state, and the first to second hybrid switching switches of the series converter are kept in or switched to the on state.

[0007] The control method of the hybrid transformer device of the present invention includes: providing a hybrid transformer device comprising a distribution transformer and at least one power electronic module, wherein the distribution transformer has a high-voltage side and a low-voltage side opposite to each other, the power electronic module has a parallel converter and a series converter electrically connected to each other, the parallel converter being electrically connected to the low-voltage side of the distribution transformer, the series converter having a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a first hybrid switching switch, and a second hybrid switching switch, the first hybrid switching switch of the series converter being electrically connected to the second hybrid switching switch and the first switching switch to the second switching switch, and the second hybrid switching switch of the series converter being electrically connected to the third switching switch to the fourth switching switch; and the series converter being electrically connected to the second switching switch. The first and second hybrid switching switches of the converter switch each other to switch the normal operation mode and bypass mode of the hybrid transformer. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the bypass mode to the normal operation mode, the first to fourth switching switches and the first hybrid switching switch to the second hybrid switching switch of the series converter are switched by pulse width modulation. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the normal operation mode to the bypass mode, the first to fourth switching switches of the series converter stop operating and remain in the closed state, and the first hybrid switching switch to the second hybrid switching switch of the series converter remains or switches to the on state.

[0008] Therefore, the present invention provides an innovative hybrid transformer and its control method, which can switch the normal operation mode and bypass mode of the hybrid transformer by means of the first to second hybrid switching switches of the series converter. In the normal operation mode, the switching loss or switching loss of the first to fourth switching switches and the first to second hybrid switching switches is reduced, thereby improving the overall efficiency of the hybrid transformer. In the bypass mode, the operating performance of the hybrid transformer can be maintained.

[0009] To make the above-described features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Additional features and advantages of the invention will be set forth in part in the following description, and these features and advantages will be partly apparent from the description or may be acquired by practice of the invention. It should be understood that both the foregoing general description and the following detailed description are illustrative and explanatory, and are not intended to limit the scope of the invention. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the circuit architecture of the first embodiment of the hybrid transformer device of the present invention;

[0011] Figure 2A and Figure 2BThe diagram shows the process flow of the hybrid transformer and its control method of the present invention in normal operation mode and bypass mode, respectively.

[0012] Figure 3 The above diagram illustrates the waveforms of the switching signals of the first to fourth switching switches and the first to second hybrid switching switches in the normal operation mode and the bypass mode of the hybrid transformer and its control method of the present invention.

[0013] Figure 4 The above diagram illustrates the waveforms of the voltage signals at the terminals of the distribution transformer and the compensation transformer in normal operation mode and bypass mode, respectively, for the hybrid transformer device and its control method of the present invention.

[0014] Figure 5 The above diagram shows the waveforms of the voltage signals at the terminals of the feeder and the compensation transformer in normal operation mode and bypass mode, respectively, for the hybrid transformer device and its control method of the present invention.

[0015] Figure 6 This is a schematic diagram of the circuit architecture of a second embodiment of the hybrid transformer device of the present invention;

[0016] Figure 7 This is a schematic diagram of the circuit architecture of a third embodiment of the hybrid transformer device of the present invention.

[0017] Explanation of reference numerals in the attached figures

[0018] 1. Hybrid transformer

[0019] 10 Distribution Transformers

[0020] 20 Power Electronics Modules

[0021] 21 Circuit Breaker

[0022] 22 First connecting terminal

[0023] 23 Parallel Converters

[0024] 23' Run signal

[0025] 24 capacitors

[0026] 25 DC voltage bus

[0027] 26 Series Converter

[0028] 27 Second connection terminal

[0029] 28 Controllers

[0030] 30 load

[0031] 40 mains power terminals

[0032] A AC signal

[0033] C capacitor

[0034] C' voltage signal

[0035] D Temperature signal

[0036] F feeder

[0037] H endpoint

[0038] HV High Voltage Side

[0039] L Inductor

[0040] L' current signal

[0041] L1 First endpoint

[0042] L2 Third Endpoint

[0043] L2' voltage signal

[0044] L3 fourth endpoint

[0045] L3' voltage signal

[0046] LV Low Voltage Side

[0047] M1 Normal Operating Mode

[0048] M2 Bypass Mode

[0049] N endpoint

[0050] N1 Second endpoint

[0051] Steps from P11 to P13

[0052] Steps on pages 21 to 22

[0053] Q1 First switching switch

[0054] Q1' First switching signal

[0055] Q2 Second Switch

[0056] Q2' Second switching signal

[0057] Q3 Third Switch

[0058] Q3' Third switching signal

[0059] Q4 Fourth switch

[0060] Q4' Fourth switching signal

[0061] S1 First Hybrid Switch

[0062] S1' First hybrid switching signal

[0063] S2 Second Hybrid Switch

[0064] S2' Second hybrid switching signal

[0065] T Compensation Transformer

[0066] T1 First endpoint

[0067] T2 Second Endpoint

[0068] V L1-N1 V L2-L3 V L3-N1 V T1-T2 Voltage Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0070] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can understand other advantages and effects of the present invention from the content disclosed in this specification, and can therefore implement or use it through other different specific equivalent embodiments.

[0071] Figure 1 This is a schematic diagram of the circuit architecture of the first embodiment of the hybrid transformer device 1 of the present invention. As shown in the figure, the hybrid transformer device 1 may include a distribution transformer 10 and at least one power electronic module 20, which are electrically connected to each other. The power electronic module 20 may have a circuit breaker 21, a first connection terminal 22, a parallel converter 23, a capacitor 24, a DC voltage bus (VDCBUS) 25, a series converter 26, a second connection terminal 27, and a controller 28, etc. The series converter 26 may have a first switching switch Q1, a second switching switch Q2, a third switching switch Q3, a fourth switching switch Q4, a first hybrid switching switch S1, a second hybrid switching switch S2, two inductors L, a capacitor C, and a compensation transformer T.

[0072] In one embodiment, the term "at least one" in this invention refers to one or more (e.g., one, two, or three or more), "plural" refers to two or more (e.g., two, three, four, or ten or more), and "electrical connection" refers to an electrical connection or coupling, etc. However, this invention is not limited to what is mentioned in the various embodiments.

[0073] In one embodiment, the distribution transformer 10 can be a conventional distribution transformer, a center-tapped distribution transformer, etc. The power electronic module 20 can be a power electronic circuit, a power electronic converter (such as a Heric power electronic converter), etc., the circuit breaker 21 can be a circuit breaker, etc., and the first connection terminal 22 or the second connection terminal 27 can be a connector, etc. The parallel converter 23 can be a solar photovoltaic (PV) converter, an energy storage device, an AC / DC converter, etc., etc., the capacitor 24 can be an electrolytic capacitor, etc., the controller 28 can be a microcontroller unit (MCU), etc., and the feeder F can be a power line, a distribution line, a transmission line, etc.

[0074] In one embodiment, any of the first switching switches Q1 to the fourth switching switches Q4 and the first hybrid switching switches S1 to the second hybrid switching switches S2 can be an insulated gate bipolar transistor (IGBT), a metal-oxide-semiconductor field-effect transistor (MOSFET), a wide band gap (WBG) switching switch (such as a WBG MOSFET), etc. The first hybrid switching switches S1 and the second hybrid switching switches S2 can switch between the normal operation mode M1 and the bypass mode M2 ​​of the hybrid transformer 1, and the normal operation mode M1 can be a voltage compensation mode or a pulse-width modulation (PWM) switching mode.

[0075] In one embodiment, the distribution transformer 10 may have a high-voltage side HV and a low-voltage side LV, and the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10 are electrically connected to the power electronics module 20, respectively. For example, the high-voltage side HV of the distribution transformer 10 may have a high voltage such as 22.8 kV, 11.4 kV, or 6.9 kV, while the low-voltage side LV of the distribution transformer 10 may have a low voltage such as 220 volts (V) or 110 volts (V).

[0076] The two ends of the circuit breaker 21 of the power electronic module 20 can be connected in parallel to the first terminal L1 (such as the live wire terminal) and the second terminal N1 (such as the neutral wire terminal) of the low voltage side LV of the distribution transformer 10, respectively. The two ends of the first connection terminal 22 can be electrically connected to the two ends of the circuit breaker 21, and the circuit breaker 21 can be electrically connected in sequence to the first connection terminal 22 and the parallel converter 23.

[0077] In bypass mode M2, the first connection terminal 22 and the second connection terminal 27 of the power electronic module 20 have a replaceable or hot-swappable function, and the parallel converter 23, capacitor 24 and the first to fourth switching switches Q1 to Q4 of the power electronic module 20 can be disposed between the first connection terminal 22 and the second connection terminal 27 to form a replaceable or hot-swappable circuit module. When a replaceable or hot-swappable circuit module (such as parallel converter 23, capacitor 24, and first to fourth switches Q1 to Q4) malfunctions (such as failing or malfunctioning), in bypass mode M2, the malfunctioning replaceable or hot-swappable circuit module (such as the malfunctioning parallel converter 23, capacitor 24, and first to fourth switches Q1 to Q4) is removed by removing the first connection terminal 22 and the second connection terminal 27, and then the normal first connection terminal 22 and the second connection terminal 27 are connected to replace it with a normal replaceable or hot-swappable circuit module (such as the normal parallel converter 23, capacitor 24, and first to fourth switches Q1 to Q4).

[0078] The parallel converter 23 can establish (generate) a rated DC voltage to the positive (+) and negative (-) terminals of the DC voltage bus 25. The parallel converter 23 can be connected in parallel with the circuit breaker 21 through the first connection terminal 22 to the low voltage side LV and feeder F of the distribution transformer 10. The parallel converter 23 can also be electrically connected to the first connection terminal 22, capacitor 24, DC voltage bus 25, series converter 26 (such as the first switching switch Q1 to the fourth switching switch Q4) and controller 28.

[0079] The positive terminal (+) of the DC voltage bus 25 can be electrically connected to the drain of the first switch Q1 and the drain of the third switch Q3, and the negative terminal (-) of the DC voltage bus 25 can be electrically connected to the source of the second switch Q2 and the source of the fourth switch Q4. One end of the capacitor 24 can be electrically connected to the parallel converter 23, the positive terminal (+) of the DC voltage bus 25, the drain of the first switch Q1 and the drain of the third switch Q3, and the other end of the capacitor 24 can be electrically connected to the parallel converter 23, the negative terminal (-) of the DC voltage bus 25, the source of the second switch Q2 and the source of the fourth switch Q4, respectively.

[0080] The first switch Q1 can be electrically connected to the second switch Q2 and the third switch Q3. Both the first switch Q1 and the third switch Q3 can be electrically connected to the positive terminal (+) of the parallel converter 23, the capacitor 24, and the DC voltage bus 25. The second switch Q2 can be electrically connected to the first switch Q1 and the fourth switch Q4. Both the second switch Q2 and the fourth switch Q4 can be electrically connected to the negative terminal (-) of the parallel converter 23, the capacitor 24, and the DC voltage bus 25. For example, the source of the first switch Q1 can be electrically connected to the drain of the second switch Q2, the drain of the first switch Q1 can be electrically connected to the drain of the third switch Q3, the source of the second switch Q2 can be electrically connected to the source of the fourth switch Q4, and the source of the third switch Q3 can be electrically connected to the drain of the fourth switch Q4. The first switch Q1 to the fourth switch Q4 can form an H-bridge switch structure.

[0081] One end of the second connection terminal 27 can be electrically connected between the first switch Q1 and the second switch Q2, and the other end of the second connection terminal 27 can be electrically connected between the third switch Q3 and the fourth switch Q4. The source of the first switch Q1 and the drain of the second switch Q2 can be electrically connected to the second connection terminal 27, and then electrically connected to the first side of the first hybrid switch S1 and one of the two inductors L (such as the first inductor). The source of the third switch Q3 and the drain of the fourth switch Q4 can be electrically connected to the second connection terminal 27, and then electrically connected to the first side of the second hybrid switch S2 and the other of the two inductors L (such as the second inductor).

[0082] The first hybrid switching switch S1 can be electrically connected to the second hybrid switching switch S2, and the electrical connection between the first hybrid switching switch S1 and the second hybrid switching switch S2 can be a common source or a common drain connection. That is, the sources of the first hybrid switching switch S1 and the second hybrid switching switch S2 can be electrically connected together, or the drains of the first hybrid switching switch S1 and the second hybrid switching switch S2 can be electrically connected together.

[0083] The first hybrid switching switch S1 and the second hybrid switching switch S2 can be electrically connected to the second connection terminal 27 and the two inductors L. The first hybrid switching switch S1 can be electrically connected between the first switching switch Q1 and the second switching switch Q2 through the second connection terminal 27, and the second hybrid switching switch S2 can be electrically connected between the third switching switch Q3 and the fourth switching switch Q4 through the second connection terminal 27.

[0084] The first sides of the two inductors L can be electrically connected to the first hybrid switching switch S1 and the second hybrid switching switch S2, respectively, and the two ends of the capacitor C can be electrically connected to the second sides of the two inductors L, respectively. One end of the capacitor C can be electrically connected to the second side of one of the two inductors L and the first terminal T1 of the compensation transformer T, and the other end of the capacitor C can be electrically connected to the second side of the other of the two inductors L and the second terminal T2 of the compensation transformer T. That is, the second sides of the two inductors L can first be connected in parallel to the two ends of the capacitor C, and then electrically connected to the first terminal T1 and the second terminal T2 of the compensation transformer, respectively.

[0085] The first terminal T1 of the compensation transformer T can be electrically connected to the second side of one of the two inductors L and one end of the capacitor C. The second terminal T2 of the compensation transformer T can be electrically connected to the second side of the other of the two inductors L and the other end of the capacitor C. The third terminal L2 of the compensation transformer T can be electrically connected to the first terminal L1 of the low-voltage side LV of the distribution transformer 10 via feeder F. The fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10 can be electrically connected to the two ends of the load 30 via feeder F, respectively. That is, the first terminal L1 of the low-voltage side LV of the distribution transformer 10 can be electrically connected to the third terminal L2 of the compensation transformer T, and the output terminals of the hybrid transformer 1 are electrically connected to the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10, respectively, to the two ends of the load 30.

[0086] The controller 28 can be electrically connected to the parallel converter 23, the DC voltage bus 25, the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2, etc. The controller 28 can generate the first switching switch signal Q1' to the fourth switching switch signal Q4' and the first hybrid switching switch signal S1' to the second hybrid switching switch signal S2', respectively, to control the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2.

[0087] The controller 28 can receive the operating signal 23' (such as a normal circuit feedback signal) of the parallel converter 23 to monitor whether the parallel converter 23 is operating normally (such as whether any abnormal state has occurred) based on the operating signal 23'. The controller 28 can also monitor whether the parallel converter 23 has established a rated DC voltage (such as a DC voltage of 380 or 400 volts) to the positive (+) and negative (-) terminals of the DC voltage bus 25. The controller 28 can receive the voltage signal C' of capacitor C, the voltage signal L2' of feeder F before adjustment (such as the voltage between the third terminal L2 of compensation transformer T and the second terminal N1 of the low voltage side LV of distribution transformer 10), the voltage signal L3' of feeder F after adjustment (such as the voltage between the fourth terminal L3 of compensation transformer T and the second terminal N1 of the low voltage side LV of distribution transformer 10), and the current signal L' of inductor L. It can also receive the temperature signal D of series converter 26 (such as at least one of the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2).

[0088] Figure 2A and Figure 2B This is a schematic diagram of the process of the hybrid transformer 1 and its control method under normal operation mode M1 and bypass mode M2 ​​of the present invention. Figure 3 This is a schematic diagram showing the waveforms of the switching signals from the first switching switch Q1 to the fourth switching switch Q4 and from the first hybrid switching switch S1 to the second hybrid switching switch S2 in normal operation mode M1 and bypass mode M2, respectively, for the hybrid transformer 1 and its control method of the present invention. Please also refer to... Figure 1 This will be explained.

[0089] In the hybrid transformer device 1 and its control method of the present invention, a hybrid transformer device 1 including a distribution transformer 10 and at least one power electronic module 20 is first provided. The distribution transformer 10 has a high voltage side HV and a low voltage side LV opposite to each other. The power electronic module 20 has a parallel converter 23 and a series converter 26 electrically connected to each other. The parallel converter 23 is electrically connected to the low voltage side LV of the distribution transformer 10. The series converter 26 has a first switching switch Q1, a second switching switch Q2, a third switching switch Q3, a fourth switching switch Q4, a first hybrid switching switch S1 and a second hybrid switching switch S2. The first hybrid switching switch S1 of the series converter 26 is electrically connected to the second hybrid switching switch S2 and the first switching switch Q1 to the second switching switch Q2. The second hybrid switching switch S2 of the series converter 26 is electrically connected to the third switching switch Q3 to the fourth switching switch Q4.

[0090] Then, the first hybrid switching switch S1 and the second hybrid switching switch S2 of the series converter 26 switch the normal operation mode M1 and the bypass mode M2 ​​of the hybrid transformer 1. When the first hybrid switching switch S1 and the second hybrid switching switch S2 of the series converter 26 switch the hybrid transformer 1 from the bypass mode M2 ​​to the normal operation mode M1, the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2 of the series converter 26 are switched by pulse width modulation (PWM). When the first hybrid switching switch S1 and the second hybrid switching switch S2 of the series converter 26 switch the hybrid transformer 1 from the normal operation mode M1 to the bypass mode M2, the first switching switch Q1 to the fourth switching switch Q4 of the series converter 26 are stopped to remain in the off state, and the first hybrid switching switch S1 to the second hybrid switching switch S2 of the series converter 26 are kept or switched to the on state.

[0091] like Figure 2A and Figure 3 As shown, in step P11, when the hybrid transformer 1 is in normal operation mode M1 or switches (returns) from bypass mode M2 ​​to normal operation mode M1, the circuit breaker 21 of the power electronic module 20 is turned on, and the first hybrid switching switch S1 to the second hybrid switching switch S2 are kept in the on state.

[0092] Next, in step P12, the parallel converter 23 is operated to establish (generate) a rated DC voltage to the positive (+) and negative (-) terminals of the DC voltage bus 25, and the operation signal 23' of the parallel converter 23 and the message that the rated DC voltage has been established to the positive (+) and negative (-) terminals of the DC voltage bus 25 are sent back to the controller 28.

[0093] Then, in step P13, the controller 28 receives the voltage signal C' of capacitor C, the voltage signal L2' of feeder F before adjustment, the voltage signal L3' of feeder F after adjustment, the current signal L' of inductor L, and the temperature signal D of series converter 26 (such as at least one of the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2). The controller 28 sends the first switching switch signal Q1', the second switching switch signal Q2', the third switching switch signal Q3', the fourth switching switch signal Q4', the first hybrid switching switch signal S1', and the second hybrid switching switch signal S2' to the first switching switch Q1, the second switching switch Q2, the third switching switch Q3, the fourth switching switch Q4, the first hybrid switching switch S1, and the second hybrid switching switch S2, respectively, so as to switch the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2 using pulse width modulation (PWM). Meanwhile, when the first hybrid switching switch S1 and the second hybrid switching switch S2 are switching in pulse width modulation (PWM), the main switching cycle of the first hybrid switching switch S1 and the second hybrid switching switch S2 is a switching frequency of 60 Hz, which helps to reduce or minimize switching losses.

[0094] like Figure 2B and Figure 3 As shown, in step P21, when the hybrid transformer 1 is in bypass mode M2 ​​or switches (returns) from normal operation mode M1 to bypass mode M2, the controller 28 can stop the operation of the first switching switch Q1 to the fourth switching switch Q4 to keep them in the closed state (non-conducting state), and the controller 28 can also keep or switch (return) the first hybrid switching switch S1 to the second hybrid switching switch S2 to the conducting state. Then, in step P22, the parallel converter 23 is stopped.

[0095] For example, with Figure 3Using the sinusoidal AC signal A (such as an AC voltage signal) as a reference, the controller 28 can generate corresponding commands according to different needs. This sends the first switching switch signals Q1' to Q4' and the first hybrid switching switch signals S1' to S2' to the first switching switch Q1 to Q4 and the first hybrid switching switch S1 to S2, respectively. The controller 28 then uses these signals to control the first switching switches Q1 to Q4 and the first hybrid switching switch S1 to S2, enabling the hybrid transformer 1 to switch between normal operation mode M1 and bypass mode M2. That is, it switches from normal operation mode M1 to bypass mode M2, or vice versa.

[0096] For example, when the hybrid transformer 1 is in or switched (restored) to normal operating mode M1, the first switching signal Q1' of the first switching switch Q1 to the fourth switching signal Q4' of the fourth switching switch Q4, and the first hybrid switching signal S1' of the first hybrid switching switch S1 to the second hybrid switching signal S2' of the second hybrid switching switch S2, are all switched using pulse width modulation (PWM) based on a sinusoidal AC signal A (such as an AC voltage signal). Simultaneously, when the first hybrid switching switch S1 and the second hybrid switching switch S2 are switching using PWM, the main switching cycle of the first hybrid switching switch S1 and the second hybrid switching switch S2 can use a switching frequency of 60 Hz, which helps to reduce or minimize switching losses.

[0097] When the hybrid transformer 1 is in bypass mode M2 ​​(or switched back), the first switching signal Q1' of the first switching switch Q1 to the fourth switching signal Q4' of the fourth switching switch Q4 are all kept at a low level, so that the first switching switch Q1 to the fourth switching switch Q4 are kept in the closed state (non-conducting state), and the first hybrid switching signal S1' of the first hybrid switching switch S1 to the second hybrid switching signal S2' of the second hybrid switching switch S2 are all kept at a high level, so that the first hybrid switching switch S1 to the second hybrid switching switch S2 are kept in the conducting state.

[0098] Figure 4 The hybrid transformer device 1 and its control method of the present invention measure the voltage signals (such as voltage V) at the terminals of the distribution transformer 10 and the compensation transformer T under normal operation mode M1 and bypass mode M2, respectively. L1-N1 Voltage V L3-N1 Voltage VT1-T2 The waveform diagram of the signal is shown below, and please refer to the accompanying documentation. Figure 1 and Figure 3 This will be explained.

[0099] For example, assuming the scenario is a transient change under the condition of compensating for a sudden 5% voltage rise, the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10 is... L1-N1 The voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10 is 220 volts * 105% = 231V (this 105% represents a 5% voltage increase from 220 volts). This voltage can be increased by the compensation mechanism of the series converter 26. L3-N1 (e.g., the voltage across load 30) is compensated to the rated voltage (e.g., 220 volts). Meanwhile, the switching process or transient change between the bypass mode M2 ​​and the normal operation mode M1 of the hybrid transformer 1 is as described below.

[0100] like Figure 3 The bypass mode M2 ​​shown can keep both the first hybrid switching switch signal S1' of the first hybrid switching switch S1 and the second hybrid switching switch signal S2' of the second hybrid switching switch S2 of the series converter 26 at a high level, so that the first hybrid switching switch S1 and the second hybrid switching switch S2 remain in the on state, thereby forming a short circuit on the primary side of the series converter 26 to achieve the bypass mode M2.

[0101] like Figure 3 The normal operating mode M1 shown can activate the compensation mechanism of the series converter 26 to switch the first switching signal Q1' of the first switching switch Q1 to the fourth switching signal Q4' of the fourth switching switch Q4 and the first hybrid switching signal S1' of the first hybrid switching switch S1 to the second hybrid switching signal S2' of the second hybrid switching switch S2 according to demand, thereby completing the voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low voltage side LV of the distribution transformer 10 (such as the two ends of the load 30). L3-N1 Compensate to the rated voltage (e.g., 220 volts).

[0102] like Figure 4 As shown in the upper part, in the bypass mode M2 ​​of the hybrid transformer 1, the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10 is... L1-N1 The voltage V is equal to the voltage between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10. L3-N1 .

[0103] In the normal operating mode M1 of the hybrid transformer 1, the scenario is set as the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10. L1-N1 The voltage Vac is 220 volts * 105% (i.e., 231V AC voltage). After the compensation mechanism of the series converter 26 switches the first switching signal Q1' of the first switching switch Q1 to the fourth switching signal Q4' of the fourth switching switch Q4 and the first mixed switching signal S1' of the first mixed switching switch S1 to the second mixed switching signal S2' of the second mixed switching switch S2, the voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low voltage side LV of the distribution transformer 10 can be switched using pulse width modulation (PWM). L3-N1 Compensate to the rated voltage (e.g., 220 volts AC voltage Vac).

[0104] like Figure 4 As shown in the lower half, in the bypass mode M2 ​​of the hybrid transformer 1, the first terminal T1 and the second terminal T2 of the compensation transformer T of the power electronics module 20 can be kept close to zero voltage (0 volts) to avoid the compensation transformer T from opening.

[0105] In the normal operation mode M1 of the hybrid transformer 1, the controller 28 can generate corresponding commands according to different needs, to send the first switching switch signal Q1' to the fourth switching switch signal Q4' and the first hybrid switching switch signal S1' to the second hybrid switching switch signal S2' to the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2, respectively. Then, the first switching switch signal Q1' of the first switching switch Q1 to the fourth switching switch Q4' and the fourth hybrid switching switch signal Q4' of the fourth switching switch Q4 and the first hybrid switching switch signal S1' of the first hybrid switching switch S1 to the second hybrid switching switch S2' are switched using pulse width modulation (PWM) to generate the corresponding voltage. Then, the voltage generated by the pulse width modulation (PWM) switching is used as the voltage V between the third terminal L2 and the fourth terminal L3 of the compensation transformer T. L2-L3 .

[0106] Figure 5 The hybrid transformer device 1 and its control method of the present invention measure the voltage signals (such as voltage V) at the terminals of the feeder F and the compensation transformer T under normal operation mode M1 and bypass mode M2, respectively. L1-N1 Voltage V L3-N1 Voltage V T1-T2 Voltage V L2-L3 The waveform diagram of the signal is shown below, and please refer to the accompanying documentation. Figure 1 and Figure 3 This will be explained.

[0107] For example, suppose the test scenario involves the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10. L1-N1 Taking a sudden drop to 210 volts as an example, the voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10 can be reduced through the compensation mechanism of the series converter 26. L3-N1 (e.g., the voltage across load 30) is compensated to the rated voltage (e.g., 220 volts).

[0108] In the bypass mode M2 ​​of the hybrid transformer 1, before the series converter 26 is started, the primary voltage of the series converter 26 is close to zero (0 volts). In the normal operation mode M1 of the hybrid transformer 1, the series converter 26 outputs compensation energy to compensate for the voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10. L3-N1 (e.g., the voltage across load 30) is compensated from the original voltage (e.g., 210 volts) to the rated voltage (e.g., 220 volts), thus verifying the feasibility of this hybrid transformer 1.

[0109] Voltage signal at the endpoints of feeder F: such as Figure 5 As shown in the upper part, in the bypass mode M2 ​​of the hybrid transformer 1, the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10 is... L1-N1 The voltage V is equal to the voltage between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10. L3-N1 .

[0110] In the normal operating mode M1 of the hybrid transformer 1, the scenario is set as the voltage V between the first terminal L1 (e.g., the live wire terminal) and the second terminal N1 (e.g., the neutral wire terminal) of the low-voltage side LV of the distribution transformer 10. L1-N1 The voltage is 210 volts. Through the compensation mechanism of the series converter 26, the first switching signal Q1' of the first switching switch Q1 to the fourth switching signal Q4' of the fourth switching switch Q4 and the first hybrid switching signal S1' of the first hybrid switching switch S1 to the second hybrid switching signal S2' of the second hybrid switching switch S2 are switched using pulse width modulation (PWM) to change the voltage V between the fourth terminal L3 of the compensation transformer T and the second terminal N1 of the low-voltage side LV of the distribution transformer 10. L3-N1 Compensate to the rated voltage (e.g., 220 volts AC voltage Vac).

[0111] The voltage signal at the terminals of the compensation transformer T: such as Figure 5 As shown in the lower half, in the bypass mode M2 ​​of the hybrid transformer 1, the voltage V between the first terminal T1 and the second terminal T2 of the compensation transformer T is... T1-T2 The condition or state will be maintained close to zero voltage (0 volts) to avoid open-circuit behavior of the compensation transformer T.

[0112] In the normal operation mode M1 of the hybrid transformer 1, the controller 28 can generate corresponding commands according to different needs, so as to send the first switching switch signal Q1' to the fourth switching switch signal Q4' and the first hybrid switching switch signal S1' to the second hybrid switching switch signal S2' to the first switching switch Q1 to the fourth switching switch Q4 and the first hybrid switching switch S1 to the second hybrid switching switch S2, respectively. Then, the first switching switch signal Q1' of the first switching switch Q1 to the fourth switching switch Q4' and the first hybrid switching switch signal S1' of the first hybrid switching switch S1 to the second hybrid switching switch S2' are switched by pulse width modulation (PWM) to generate the corresponding voltage. Then, the voltage generated by pulse width modulation (PWM) is output as the voltage V between the third terminal L2 and the fourth terminal L3 of the compensation transformer T through the compensation transformer T. L2-L3 .

[0113] Figure 6 This is a schematic diagram of the circuit architecture of a second embodiment of the hybrid transformer device 1 of the present invention. As shown, the hybrid transformer device 1 may have two identical (e.g., identical circuit structures) power electronic modules 20, and the distribution transformer 10 may be in the form of a center tap with a predetermined voltage (e.g., 110 volts) so that the hybrid transformer device 1 and its control method can adjust and compensate for the voltage of the center tap distribution transformer 10.

[0114] For example, the second terminal N1 (such as the neutral terminal) of the low-voltage side LV of the distribution transformer 10 can be set at or adjusted to the center tap of the low-voltage side LV to evenly distribute the voltage of the low-voltage side LV of the distribution transformer 10 through the same two power electronic modules 20, so that each of the two power electronic modules 20 outputs half of the voltage of the low-voltage side LV of the distribution transformer 10. For example, the voltage at the upper and lower ends of the low-voltage side LV of the distribution transformer 10 can be evenly distributed (halved) from 220 volts so that the voltage of the feeder F connected to the upper power electronic module 20 is 110 volts, the voltage of the middle feeder F is 0 volts (because the second terminal N1 or terminal N of the center tap is electrically connected to the ground terminal), and the voltage of the feeder F connected to the lower power electronic module 20 is -110 volts.

[0115] Figure 7This is a schematic diagram of the circuit architecture of a third embodiment of the hybrid transformer device 1 of the present invention. As shown, the distribution transformer 10 may have a high-voltage side HV (e.g., 22.8 kV, 11.4 kV, or 6.9 kV) and a low-voltage side LV (e.g., 220 V or 110 V).

[0116] The two ends of the power electronic module 20 (circuit breaker 21) can be electrically connected to the first terminal L1 and the second terminal N1 (the two ends of the load 30) of the low-voltage side LV of the distribution transformer 10, respectively, so that the power electronic module 20 maintains the same low voltage condition or state as the low-voltage side LV. At the same time, the third terminal L2 of the compensation transformer T and the terminal H of the mains terminal 40 can be electrically connected to the two ends of the high-voltage side HV of the distribution transformer 10, respectively, and the fourth terminal L3 of the compensation transformer T can be electrically connected to the mains terminal 40, so as to feed back the voltage signal output by the compensation transformer T to the high-voltage side HV of the distribution transformer 10.

[0117] In summary, the hybrid transformer and its control method of the present invention have at least the following features, advantages, or technical effects:

[0118] 1. The first to second hybrid switching switches of the series converter of the present invention can switch between the normal operation mode and the bypass mode of the hybrid transformer. In the normal operation mode, the switching loss or switching loss of the first to fourth switching switches and the first to second hybrid switching switches can be reduced, thereby improving the overall efficiency of the hybrid transformer. In the bypass mode, the operating performance of the hybrid transformer can be maintained.

[0119] Second, when the first to second hybrid switching switches of the series converter of the present invention perform pulse width modulation (PWM) switching, the main switching period of the first to second hybrid switching switches is a switching frequency of 60 Hz, which is beneficial to reduce or lower switching losses.

[0120] Third, when no compensation is needed or a fault occurs, the hybrid transformer of the present invention can control the first to second hybrid switching switches of the series converter to facilitate the automatic execution of the bypass mode (bypass function) of the hybrid transformer.

[0121] Fourth, in the bypass mode of the hybrid transformer device, the first and second terminals of the compensation transformer can maintain a condition or state close to zero voltage (0 volts) to avoid the compensation transformer from opening.

[0122] Fifth, the present invention can arrange the parallel converter, capacitor and the first to fourth switching switches of the power electronic module between the first and second connection terminals to form a replaceable circuit module or a hot-swappable circuit module. This is beneficial because when the power electronic module malfunctions, it can be directly replaced in bypass mode, thereby improving the replacement flexibility or maintenance efficiency of the power electronic module.

[0123] The above embodiments are merely illustrative of the principles, features, and effects of the present invention and are not intended to limit the scope of implementation of the present invention. Any person skilled in the art can modify and alter the above embodiments without departing from the spirit and scope of the present invention. Any equivalent changes and modifications made using the content disclosed in this invention should still be covered by the claims. Therefore, the scope of protection of this invention should be as set forth in the claims.

Claims

1. A hybrid transformer, comprising: A distribution transformer has a high-voltage side and a low-voltage side; as well as At least one power electronic module has a parallel converter and a series converter electrically connected to each other. The parallel converter is electrically connected to the low-voltage side of the distribution transformer. The series converter has a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a first hybrid switching switch, and a second hybrid switching switch. The first hybrid switching switch of the series converter is electrically connected to the second hybrid switching switch and the first switching switch to the second switching switch. The second hybrid switching switch of the series converter is electrically connected to the third switching switch to the fourth switching switch. The first and second hybrid switching switches of the series converter switch each other to switch the normal operation mode and bypass mode of the hybrid transformer. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the bypass mode to the normal operation mode, the first to fourth switching switches and the first hybrid switching switches to the second hybrid switching switches of the series converter are switched by pulse width modulation. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the normal operation mode to the bypass mode, the first to fourth switching switches of the series converter stop operating and remain in the off state, and the first to second hybrid switching switches of the series converter remain in or switch to the on state.

2. The hybrid transformer as described in claim 1, wherein, The power electronic module also has a circuit breaker and a first connection terminal. The two ends of the circuit breaker are respectively connected in parallel to the first end and the second end of the low voltage side of the distribution transformer. The two ends of the first connection terminal are respectively electrically connected to the two ends of the circuit breaker. The circuit breaker is sequentially electrically connected to the first connection terminal and the parallel converter.

3. The hybrid transformer as described in claim 1, wherein, The power electronic module also has a first connection terminal and a second connection terminal, the first connection terminal and the second connection terminal having a replaceable function or a hot-swappable function, and the parallel converter of the power electronic module and the first to fourth switching switches are disposed between the first connection terminal and the second connection terminal to jointly form a replaceable circuit module or a hot-swappable circuit module.

4. The hybrid transformer as described in claim 1, wherein, The power electronic module also has a DC voltage bus, a first connection terminal and a circuit breaker. The parallel converter establishes a rated DC voltage to the positive and negative terminals of the DC voltage bus. The parallel converter is connected in parallel with the circuit breaker through the first connection terminal to the low voltage side and feeder of the distribution transformer. The parallel converter is electrically connected to the first connection terminal, the DC voltage bus and the series converter.

5. The hybrid transformer as described in claim 1, wherein, The power electronic module also has a DC voltage bus, the positive terminal of which is electrically connected to the drain of the first switch and the drain of the third switch, and the negative terminal of which is electrically connected to the source of the second switch and the source of the fourth switch.

6. The hybrid transformer as claimed in claim 1, wherein, The power electronic module also has a first connection terminal, a second connection terminal and two inductors. The parallel converter of the power electronic module and the first to fourth switching switches are disposed between the first connection terminal and the second connection terminal. The first switching switch and the second switching switch are electrically connected to the second connection terminal and then electrically connected to the first hybrid switching switch and one of the two inductors. The third switching switch and the fourth switching switch are electrically connected to the second connection terminal and then electrically connected to the second hybrid switching switch and the other of the two inductors.

7. The hybrid transformer as claimed in claim 1, wherein, The source of the first switching switch is electrically connected to the drain of the second switching switch, the drain of the first switching switch is electrically connected to the drain of the third switching switch, the source of the second switching switch is electrically connected to the source of the fourth switching switch, the source of the third switching switch is electrically connected to the drain of the fourth switching switch, and the first switching switch to the fourth switching switch form an H-bridge switch structure.

8. The hybrid transformer as claimed in claim 1, wherein, The series converter also includes two inductors, a capacitor and a compensation transformer. The first sides of the two inductors are electrically connected to the first hybrid switching switch and the second hybrid switching switch, respectively. The two ends of the capacitor are electrically connected to the second sides of the two inductors, respectively. One end of the capacitor is electrically connected to the second side of one of the two inductors and the first terminal of the compensation transformer, and the other end of the capacitor is electrically connected to the second side of the other of the two inductors and the second terminal of the compensation transformer.

9. The hybrid transformer as claimed in claim 1, wherein, The power electronic module also has a controller, which is electrically connected to the parallel converter, the first switching switch to the fourth switching switch and the first hybrid switching switch to the second hybrid switching switch respectively. The controller generates the first switching switch signal to the fourth switching switch signal and the first hybrid switching switch signal to the second hybrid switching switch respectively to control the first switching switch to the fourth switching switch and the first hybrid switching switch to the second hybrid switching switch respectively.

10. The hybrid transformer as claimed in claim 1, wherein, The power electronic module also has a controller and a DC voltage bus. The controller receives the operating signal of the parallel converter to monitor whether the parallel converter is operating normally based on the operating signal, and the controller monitors whether the parallel converter has established a rated DC voltage to the positive and negative terminals of the DC voltage bus.

11. The hybrid transformer as claimed in claim 1, comprising two identical power electronic modules, wherein, The distribution transformer is a center-tapped type. The neutral line terminal of the low-voltage side of the distribution transformer is located at the center tap of the low-voltage side, so that the voltage of the low-voltage side of the distribution transformer is evenly distributed through the two power electronic modules, so that each of the two power electronic modules outputs half of the voltage of the low-voltage side of the distribution transformer.

12. The hybrid transformer as claimed in claim 1, wherein, The series converter also includes a compensation transformer. The two ends of the power electronic module are electrically connected to the first and second terminals of the low-voltage side of the distribution transformer, respectively, so that the power electronic module maintains the same low-voltage conditions or state as the low-voltage side. One terminal and one mains terminal of the compensation transformer are electrically connected to the two ends of the high-voltage side of the distribution transformer, respectively, and the other terminal of the compensation transformer is electrically connected to the mains terminal, so that the voltage signal output by the compensation transformer is fed back to the high-voltage side of the distribution transformer.

13. A control method for a hybrid transformer, comprising: A hybrid transformer device is provided, comprising a distribution transformer and at least one power electronic module. The distribution transformer has a high-voltage side and a low-voltage side opposite to each other. The power electronic module has a parallel converter and a series converter electrically connected to each other. The parallel converter is electrically connected to the low-voltage side of the distribution transformer. The series converter has a first switching switch, a second switching switch, a third switching switch, a fourth switching switch, a first hybrid switching switch, and a second hybrid switching switch. The first hybrid switching switch of the series converter is electrically connected to the second hybrid switching switch and the first switching switch to the second switching switch. The second hybrid switching switch of the series converter is electrically connected to the third switching switch to the fourth switching switch. The first and second hybrid switching switches of the series converter switch each other to switch the normal operation mode and bypass mode of the hybrid transformer. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the bypass mode to the normal operation mode, the first to fourth switching switches and the first hybrid switching switches to the second hybrid switching switches of the series converter are switched by pulse width modulation. When the first and second hybrid switching switches of the series converter switch the hybrid transformer from the normal operation mode to the bypass mode, the first to fourth switching switches of the series converter stop operating and remain in the closed state, and the first to second hybrid switching switches of the series converter remain in or switch to the on state.

14. The control method as described in claim 13, wherein, The method further includes turning on the circuit breaker of the power electronic module and operating the parallel converter when the hybrid transformer switches from the bypass mode to the normal operation mode, so that the parallel converter establishes a rated DC voltage on the DC voltage bus, and transmitting the operating signal of the parallel converter and the information that the rated DC voltage has been established on the DC voltage bus back to the controller.

15. The control method as described in claim 13, wherein, The method further includes using a 60 Hz switching frequency for the main switching cycle of the first hybrid switching switch and the second hybrid switching switch when the pulse width modulation is being performed, so as to reduce switching losses.

16. The control method as described in claim 13, wherein, The method further includes, when the hybrid transformer switches from the normal operation mode to the bypass mode, the controller stops the operation of the first switching switch to the fourth switching switch to maintain the closed state, keeps or switches the first hybrid switching switch to the second hybrid switching switch to the on state, and stops the operation of the parallel converter.

17. The control method as described in claim 13, wherein, The method further includes keeping the first switching signal of the first switching switch to the fourth switching signal of the fourth switching switch low when the hybrid transformer switches from the normal operation mode to the bypass mode, so that the first switching switch to the fourth switching switch remains in the closed state, and keeping the first hybrid switching signal of the first hybrid switching switch to the second hybrid switching signal of the second hybrid switching switch high, so that the first hybrid switching switch to the second hybrid switching switch remains in the on state.

18. The control method as described in claim 13, wherein, The method further includes, in the normal operating mode of the hybrid transformer, switching the switching signal from the first switching switch to the switching signal from the fourth switching switch and the hybrid switching signal from the first hybrid switching switch to the hybrid switching signal from the second hybrid switching switch through the compensation mechanism of the series converter, so as to compensate the voltage between the terminal of the compensation transformer of the power electronic module and the terminal of the low voltage side of the distribution transformer to the rated voltage.

19. The control method as described in claim 13, wherein, The method further includes maintaining the first and second terminals of the power electronic module's compensation transformer at near-zero voltage in the bypass mode of the hybrid transformer, and in the normal operation mode of the hybrid transformer, switching the first switching switch to the fourth switching switch and the first hybrid switching switch to the second hybrid switching switch by pulse width modulation to generate the corresponding voltage, and then using the voltage generated by the pulse width modulation switching as the voltage between the third and fourth terminals of the compensation transformer through the compensation transformer.

20. The control method as described in claim 13, wherein, The method also includes, in the bypass mode of the hybrid transformer and before the series converter is started, bringing the primary voltage of the series converter close to zero voltage, while in the normal operation mode of the hybrid transformer, the series converter outputs compensation energy to compensate the voltage between the terminals of the compensation transformer of the power electronic module and the terminals of the low voltage side of the distribution transformer from the original voltage to the rated voltage.

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