Hybrid power electronic transformer, system, voltage regulation method and related equipment

Abstract

The invention relates to the technical field of power transmission conversion and operation control of a power grid transformer, and discloses a hybrid power electronic transformer, a system, a voltage regulation method and related equipment. The invention discloses a hybrid power electronic transformer which is simpler in structure, higher in efficiency, lower in cost and lower in loss and meets the alternating-current and direct-current hybrid power supply requirement. The hybrid power electronic transformer comprises a winding transformer and a power electronic circuit, the winding transformer is used for voltage grade conversion; the power electronic circuit is used for voltage bidirectional regulation; the winding transformer comprises a magnetic core, and a primary winding, a first secondary winding and a second secondary winding which are arranged on two sides of the magnetic core; the primary winding is connected with a high-voltage alternating-current input end, and the first secondary winding is connected with a low-voltage alternating-current output end; the second secondary winding is connected with the first end of the power electronic circuit, the second end of the power electronic circuit is connected with the low-voltage alternating current output end, and the third end of the power electronic circuit is connected with the low-voltage direct current output end.

Description

Technical Field

[0001] This application relates to the field of power transmission, transformation and operation control technology of power grid transformers, and in particular to a hybrid power electronic transformer, system, voltage regulation method and related equipment. Background Art

[0002] With the acceleration of global energy transition and the rapid development of renewable energy, the power grid has an increasing demand for efficient, flexible and reliable power equipment. Traditional distribution transformers only have the basic functions of voltage level transformation and power transmission, and cannot dynamically control their load voltage and grid current in real time.

[0003] In related technologies, on-load tap changers (OLTCs) adjust the output voltage by changing the turns ratio of the windings, enabling adjustment of the transformer output voltage without power interruption. However, they cannot continuously and smoothly adjust the voltage, have poor reliability, and lack harmonic mitigation capabilities. Power electronic transformers (PETs) rely entirely on power electronic devices and high-frequency transformer isolation devices to achieve voltage level conversion and energy transfer. They are extremely expensive, have no particular advantage in efficiency, and have a very low cost-performance ratio, so they are rarely used in practical applications. Hybrid power electronic transformers (HPETs) integrate power electronic devices with traditional transformers, possessing the efficiency of traditional transformers while also taking into account the flexible adjustment functions of power electronic devices. Therefore, they have received widespread attention in the market.

[0004] However, with the large-scale integration of distributed energy and various DC loads into the distribution network, traditional hybrid power electronic transformers typically only have AC input ports on the high-voltage side and AC output ports on the low-voltage side, which cannot directly meet the demand for AC / DC hybrid power supply. Furthermore, the magnetic circuits and winding structures of traditional hybrid power electronic transformers are relatively complex and numerous, resulting in limited efficiency, high losses, and high costs, which cannot meet the development needs of active distribution networks. Summary of the Invention

[0005] This application provides a hybrid power electronic transformer, system, voltage regulation method, and related equipment to address the problems that traditional hybrid power electronic transformers cannot meet the requirements of AC / DC mixed power supply, and that have complex magnetic circuits and winding structures, large quantities, limited efficiency, high losses, and high costs, thus failing to meet the power management needs of active distribution networks.

[0006] The first aspect of this application provides a hybrid power electronic transformer, characterized in that it includes: a winding transformer and a power electronic circuit; Winding transformers are used for voltage level transformation, and power electronic circuits are used for bidirectional voltage regulation; A winding transformer includes a magnetic core, and a primary winding, a first secondary winding, and a second secondary winding located on both sides of the magnetic core. The primary winding is connected to the high-voltage AC input terminal, and the first secondary winding is connected to the low-voltage AC output terminal; The second secondary winding is connected to the first terminal of the power electronic circuit, the second terminal of the power electronic circuit is connected to the low-voltage AC output terminal, and the third terminal of the power electronic circuit is connected to the low-voltage DC output terminal.

[0007] The second aspect of this application provides an AC / DC hybrid power supply system, characterized in that it includes a target power grid, an AC load, a DC source-grid-load-storage system, and at least one of the above-mentioned hybrid power electronic transformers; The target power grid is connected to the high-voltage AC input terminal of the hybrid power electronic transformer; The low-voltage DC output terminal of the hybrid power electronic transformer is connected to the DC power grid, load, and energy storage via a common DC bus. The low-voltage AC output terminal of the hybrid power electronic transformer is connected to the AC load via a common AC bus.

[0008] A third aspect of this application provides a voltage regulation method, characterized in that it is applied to the aforementioned hybrid power electronic transformer or AC / DC hybrid power supply system, and the voltage regulation method includes: Obtain the actual output parameters of the low-voltage AC output terminal; The parameter modulation signal is obtained based on the difference between the actual output parameters and the target output parameters and the preset control function; The output voltage of the low-voltage AC output terminal is adjusted according to the parameter modulation signal. A fourth aspect of this application provides a voltage regulating device, characterized in that it is applied to the aforementioned hybrid power electronic transformer or AC / DC hybrid power supply system, and the voltage regulating device includes: The acquisition unit is used to acquire the actual output parameters of the low-voltage AC output terminal. The determining unit is used to obtain the parameter modulation signal based on the difference between the actual output parameters and the target output parameters and the preset control function; The feedback regulation unit is used to adjust the output voltage of the low-voltage AC output terminal according to the parameter modulation signal.

[0009] The fifth aspect of this application provides a hybrid power electronic converter control system including a controller, power electronic circuits, and a winding transformer; The voltage of the winding transformer is regulated by the power electronic circuit controlled by the controller, and the hybrid power electronic converter control system executes the voltage regulation method described above.

[0010] A sixth aspect of this application provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the voltage regulation method described above.

[0011] The technical solution provided in this application offers a three-port hybrid power electronic transformer, including a winding transformer comprising a primary winding, a first secondary winding, and a second secondary winding located on both sides of a magnetic core. The primary winding is connected to a high-voltage AC input terminal, and the first secondary winding is connected to a low-voltage AC output terminal to achieve voltage level variation and provide a low-voltage AC output. The third terminal of the power electronic circuit is connected to a low-voltage DC output terminal to provide a low-voltage DC output. The second secondary winding is connected to the first terminal of the power electronic circuit, and the second terminal of the power electronic circuit is directly connected to the low-voltage AC output terminal. The power electronic circuit enables bidirectional voltage regulation, ensuring stable output from both the low-voltage DC and low-voltage AC output terminals. This hybrid power electronic transformer has a simpler structure, higher efficiency, lower cost, and lower losses, making it easier to widely promote. It can meet the needs of flexible output voltage adjustment and comprehensive power quality management, actively adapting to the access of DC loads such as distributed power sources and electric vehicle charging piles, and providing strong support for the rapid development of active power distribution networks. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the first embodiment of the hybrid power electronic transformer in this application; Figure 2 This is a schematic diagram of the second embodiment of the hybrid power electronic transformer in this application; Figure 3 This is a schematic diagram of the third embodiment of the hybrid power electronic transformer in this application; Figure 4 This is a schematic diagram of one embodiment of the AC / DC hybrid power supply system in this application; Figure 5 This is a schematic diagram of another embodiment of the AC / DC hybrid power supply system in this application; Figure 6 This is a schematic diagram of an embodiment of the voltage regulation method in this application; Figure 7 This is a schematic diagram of a single-phase equivalent circuit in this application; Figure 8 This is a schematic diagram of one embodiment of the voltage regulation device in this application; Figure 9 This is a schematic diagram of an embodiment of the hybrid power electronic converter control system in this application; Figure 10 A schematic diagram of the control principle of the hybrid power electronic converter control system in this application; Figure 11This is a schematic diagram of the control principle of the controller in this application; Figure 12 This is a schematic diagram of the control principle of the voltage control module in this application. Detailed Implementation

[0013] This application provides a hybrid power electronic transformer, system, voltage regulation method, and related equipment, which is used to provide a hybrid power electronic transformer with simpler structure, higher efficiency, lower cost, and lower loss to meet the needs of AC / DC hybrid power supply.

[0014] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in a sequence other than that illustrated or described herein. Furthermore, the terms “comprising” or “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0015] Please see Figure 1 The first embodiment of the hybrid power electronic transformer in this application includes a hybrid power electronic transformer 100 comprising a winding transformer 11 and a power electronic circuit 12. The winding transformer 11 is used for voltage level transformation, and the power electronic circuit 12 is used for bidirectional voltage regulation; The winding transformer 11 includes a magnetic core 114, and a primary winding 111, a first secondary winding 112 and a second secondary winding 113 disposed on both sides of the magnetic core; The primary winding 111 is connected to the high-voltage AC input terminal HV, and the first secondary winding 112 is connected to the low-voltage AC output terminal LV. The second secondary winding 113 is connected to the first terminal of the power electronic circuit 12, the second terminal of the power electronic circuit 12 is connected to the low-voltage AC output terminal LV, and the third terminal of the power electronic circuit 12 is connected to the low-voltage DC output terminal DC to provide low-voltage DC voltage output. In this embodiment, the low-voltage DC output terminal provided by the power electronic circuit can actively adapt to the access of DC loads such as distributed power sources and electric vehicle charging piles, providing strong support for the rapid development of active power distribution networks. Through the connection relationship between the power electronic circuit and the winding transformer, bidirectional voltage regulation can be achieved, ensuring stable output of the low-voltage DC output terminal and the low-voltage AC output terminal, realizing flexible adjustment of output voltage and comprehensive power quality management.

[0016] This embodiment provides a three-port hybrid power electronic transformer, including a winding transformer comprising a primary winding, a first secondary winding, and a second secondary winding located on both sides of a magnetic core. The primary winding is connected to a high-voltage AC input terminal, and the first secondary winding is connected to a low-voltage AC output terminal to achieve voltage level variation and provide a low-voltage AC output, which can meet the requirements of AC / DC hybrid power supply. In this embodiment, the power electronic circuit is directly connected to the first secondary winding of the low-voltage AC output, and the power electronic circuit directly draws energy from the low-voltage AC output terminal, avoiding the increase in transformer winding cost and unnecessary additional winding losses caused by adding an extra energy-drawing winding. At the same time, it can also realize rapid feedback adjustment of the output parameters of the low-voltage AC output terminal, reduce intermediate links, simplify the structure of the hybrid power electronic transformer, reduce the number of windings, improve the high-to-low voltage conversion efficiency, reduce losses, reduce the cost of the hybrid power electronic transformer, and facilitate widespread promotion.

[0017] To further reduce the cost of hybrid power electronic transformers and provide a simple, stable AC / DC hybrid power supply, refer to Figure 2 , 3 A second embodiment of the hybrid power electronic transformer of this application is provided: The hybrid power electronic transformer includes a winding transformer 11 for voltage level transformation and a power electronic circuit 12 for bidirectional voltage regulation. The winding transformer 11 includes a magnetic core 114, and a primary winding 111, a first secondary winding 112, and a second secondary winding 113 disposed on both sides of the magnetic core. The primary winding 111 is connected to the high-voltage AC input terminal HV, and the first secondary winding 112 is connected to the low-voltage AC output terminal LV.

[0018] The power electronic circuit 12 includes a voltage control module (VC) and a voltage providing module (VP). The voltage control module VC and the power harvesting module VP each have an AC port and a DC port. In this embodiment, the power harvesting module VP includes an AC / DC conversion circuit, and the voltage control module VC includes a DC / AC conversion circuit.

[0019] The AC port of the voltage control module VC is connected to the second secondary winding 113, and the AC port of the energy harvesting module VP is connected to the first secondary winding 112; the DC port of the voltage control module VC is connected to the DC port of the energy harvesting module VP, and is also connected to the low-voltage DC output terminal DC.

[0020] It is understood that the AC port of the energy harvesting module VP in this embodiment is connected to the first secondary winding, which can directly obtain the low-voltage AC output energy output by the first secondary winding. This avoids the increase in transformer winding cost and unnecessary additional winding losses caused by adding an extra energy harvesting winding. At the same time, it can also realize the rapid feedback adjustment of the output parameters of the low-voltage AC output terminal.

[0021] It should be further explained that common-mode interference suppression can be achieved in the power harvesting module VP using either hardware common-mode filters or software common-mode voltage suppression algorithms. For example, a filter can be set in the power harvesting module VP to reduce the common-mode voltage and common-mode current interference caused by the direct connection of the power harvesting module VP to the first secondary winding. This eliminates the need for additional power harvesting windings for power frequency isolation, reduces intermediate links, simplifies the structure of the hybrid power electronic transformer, reduces the number of windings, improves the high-to-low voltage conversion efficiency, reduces losses, and lowers the cost of the hybrid power electronic transformer, which is conducive to its widespread adoption.

[0022] To facilitate understanding, the voltage regulation process of the power electronic circuit in this embodiment is explained. The voltage control module VC and the energy harvesting module VP are respectively connected to the second secondary winding and the first secondary winding. The output voltage of the first secondary winding can be flexibly controlled by a controller that is set externally or inside the hybrid power electronic transformer. The energy harvesting module VP can directly obtain the actual output parameters of the first secondary winding. Based on the control function preset by the controller, it can drive the power devices in the voltage control module VC to adjust the corresponding parameters of the second secondary winding 113 connected to the voltage control module VC. The second secondary winding 113 compensates the primary winding 111 through the magnetic core 114. The compensated primary winding 111 adjusts the output parameters of the first secondary winding through the magnetic core 114, thereby realizing the feedback regulation of the output parameters of the first secondary winding. Based on the above topology, the power electronic circuit in this embodiment can achieve rapid feedback regulation through the voltage control module and the energy harvesting module, maintaining the stability of the low-voltage AC output of the first secondary winding and the low-voltage DC port output provided by the power electronic circuit.

[0023] Furthermore, in this embodiment, a low-voltage DC output port is led out through the connection between the DC port of the voltage control module and the DC port of the energy harvesting module. Traditional transformers or other hybrid transformers require a separate AC / DC conversion circuit to output the transformer's DC port. The power electronic circuit of this embodiment integrates and coordinates the control of both low-voltage AC and low-voltage DC output ports. Through the coupling of the DC port, both low-voltage AC and low-voltage DC output ports can be directly decoupled and balanced through the independent decoupling control of the power electronic circuit. This improves the regulation capability of AC / DC source load access and the carrying capacity of large-capacity loads. It greatly simplifies the topology of the hybrid power electronic transformer, reduces the cost of the hybrid power electronic transformer, and is conducive to its widespread adoption.

[0024] Optionally, a DC bus capacitor is connected between the DC port of the voltage control module VC and the DC port of the energy harvesting module VP. The number of DC bus capacitors can be one, or the appropriate number can be selected according to actual needs.

[0025] In this embodiment, the power of both the voltage control module VC and the energy harvesting module VP can flow freely in both directions, enabling bidirectional voltage regulation of the hybrid transformer. It can regulate upward or downward, and its regulation capability is achieved through the controller inside the hybrid power electronic transformer.

[0026] The first primary winding and the first secondary winding form a low-voltage AC output circuit 31 through the magnetic core 114; the second primary winding and the second secondary winding form a low-voltage AC compensation circuit 32 through the magnetic core 114.

[0027] The aforementioned magnetic core 114 includes two magnetic circuits C11 and C12. To simplify the structure and reduce costs, these two magnetic circuits adopt a conjugate structure. Among them, C11 is the main magnetic circuit, serving as the isolation side in the low-voltage AC output circuit 31. Together with the first primary winding and the first secondary winding, it forms the high-low voltage conversion main circuit to realize the electromagnetic coupling isolation conversion output of high- and low-voltage electrical energy of the hybrid power electronic transformer.

[0028] C12 is a secondary magnetic circuit, serving as the isolation side of the low-voltage AC compensation circuit 32. It enables the regulation function of the power electronic circuit of the hybrid power electronic transformer. The magnetic circuit 12 electromagnetically couples the compensation voltage of the voltage control module VC to the second primary winding (i.e., the high-voltage compensation winding) through the second secondary winding. The first primary winding and the second primary winding are connected in series. After the compensation voltage is applied, the voltage of the first primary winding is also adjusted. Then, the output voltage of the first secondary winding (i.e., the low-voltage output secondary winding) is adjusted through the main magnetic circuit C11, thus realizing the feedback regulation of the low-voltage AC side voltage.

[0029] Specifically, the first primary winding includes three-phase primary windings, also known as high-voltage primary windings, and the second primary winding includes three-phase compensation windings, also known as high-voltage compensation windings. Each phase primary winding and its corresponding compensation winding are connected in series to form a delta connection structure and are connected to the three-phase interface of the high-voltage AC input terminal, such as... Figure 3 As shown, the first primary winding consists of HR11, HR21, and HR31, and the second primary winding consists of HR12, HR22, and HR32. One end of winding HR11 is connected to the first phase interface of the high-voltage AC input terminal, and the other end of winding HR11 is connected in series with one end of winding HR12. The other end of winding HR12 is connected to one end of winding HR21, one end of winding HR21 is connected to the second phase interface of the high-voltage AC input terminal, the other end of winding HR21 is connected in series with one end of winding HR22, the other end of winding HR22 is connected in series with one end of winding HR31, one end of winding HR31 is connected to the third phase interface of the high-voltage AC input terminal, and the other end of winding HR31 is connected to one end of winding HR11.

[0030] Optionally, the power electronic circuit 12 in this embodiment can be connected with reference to the second embodiment, wherein the energy harvesting module VP is a three-phase four-wire output (with neutral wire) that supports three-phase unbalanced current compensation of the load.

[0031] Optionally, the voltage control module VC is a three-phase output, with a topology of either a three-phase fully controlled bridge inverter or three independent single-phase H-bridge inverters. The three-phase fully controlled bridge inverter can be adapted to the delta-structured low-voltage regulating windings LR12 / LR22 / LR32, while the three independent single-phase H-bridge inverters can be adapted to the star-structured low-voltage regulating windings LR12 / LR22 / LR32.

[0032] Specifically, the voltage control module VC adjusts the amplitude and phase of its output voltage according to the set value of the output voltage on the low-voltage AC side (LR11 / LR21 / LR31). This is coupled and superimposed to the high-voltage compensation winding HR12 / HR22 / HR32 through the low-voltage regulating winding LR12 / LR22 / LR32, thereby reversely regulating the output voltage of the low-voltage output secondary winding LR11 / LR21 / LR31. This provides stepless real-time voltage regulation, three-phase imbalance compensation, and power factor compensation functions.

[0033] This embodiment provides a three-port hybrid power electronic transformer. The first primary winding is connected to the high-voltage AC input terminal and achieves high-to-low voltage conversion through the main magnetic circuit and the first secondary winding. The first secondary winding is connected to the low-voltage AC output section. The first primary winding and the second primary winding are connected in series and form a low-voltage AC compensation circuit through the secondary magnetic circuit and the second secondary winding. The second secondary winding is connected to the voltage control module VC, and the first secondary winding is connected to the energy harvesting module VP, so that the energy harvesting module VP can directly harvest energy from the actual output of the low-voltage AC output. The voltage control module VC can adjust the amplitude and phase of its output voltage according to the set value of the low-voltage AC output voltage. This is coupled to the primary winding through the second secondary winding, thereby adjusting the output voltage of the first secondary winding, providing stepless real-time voltage regulation and three-phase operation. The hardware foundation for current imbalance compensation and reactive power factor compensation functions is provided. Furthermore, the DC port between the voltage control module VC and the energy extraction module VP, and the low-voltage DC output interface DC, utilizes the voltage regulation of the power electronic circuit to achieve a stable DC voltage output. In this embodiment, the energy extraction module VP is directly connected to the first secondary winding of the low-voltage AC output. The power electronic circuit directly extracts energy from the low-voltage AC output, avoiding the increased cost of transformer windings and unnecessary additional winding losses caused by adding extra energy extraction windings. Simultaneously, it enables rapid feedback adjustment of the output parameters at the low-voltage AC output, reducing intermediate links, simplifying the structure of the hybrid power electronic transformer, reducing the number of windings, improving high-to-low voltage conversion efficiency, lowering losses, and reducing the cost of the hybrid power electronic transformer, facilitating widespread adoption.

[0034] The hybrid power electronic transformer provided in this application is used in scenarios where the power grid provides hybrid AC / DC power supply, referring to... Figure 4 One embodiment of the AC / DC hybrid power supply system of this application includes only a section of power grid and a hybrid power electronic transformer.

[0035] Specifically, the target power grid AC is connected to the high-voltage AC input terminal HV of the hybrid power electronic transformer 100; the low-voltage DC output terminal DC of the hybrid power electronic transformer 100 is connected to the DC source-grid-load-storage system via a common DC bus; and the low-voltage AC LV output terminal of the hybrid power electronic transformer 100 is connected to the AC load via a common AC bus.

[0036] In this embodiment, the low-voltage DC output interface (DC) and AC output interface (LV) can realize hybrid AC / DC power supply, providing a common DC bus for the hybrid AC / DC power supply system. On the common DC bus, a self-balancing integrated DC microgrid for energy storage, distributed power sources, and DC loads can be constructed.

[0037] The DC source-grid-load-storage system includes energy storage, charging piles, distributed energy, and DC loads. The energy extraction module VP of the hybrid electronic power transformer 100 is responsible for the stable control of the low-voltage DC output voltage, establishing a common DC bus. DC source-grid-storage devices such as energy storage, charging piles, distributed energy (such as photovoltaics), and DC loads are connected to this common DC bus and then connected to the DC bus via DC-DC converters to construct a DC microgrid.

[0038] In this embodiment, the DC source, load, and storage are prioritized to achieve balance. The unbalanced portion of power is balanced with the low-voltage AC power output through the energy extraction AC / DC module VP and the voltage control module VC. Power can flow bidirectionally and mutually support each other between the AC power supply and the DC microgrid. Therefore, it realizes the flexible adjustment and mutual support capability of AC / DC hybrid power supply, which helps to prevent overload of the winding transformer itself, and at the same time improves the flexible access capability and load-bearing capacity of the DC source and load.

[0039] See Figure 5 This application provides another embodiment of the AC / DC hybrid power supply system, which includes only two power grid segments and two hybrid power electronic transformers.

[0040] Specifically, the target power grid includes a first power grid and a second power grid; the first power grid is connected to the high-voltage AC input terminal of a hybrid power electronic transformer 100A, and the second power grid is connected to the high-voltage AC input terminal of another hybrid power electronic transformer 100B; the low-voltage DC output terminals of each hybrid power electronic transformer are connected through a common DC bus, that is, the low-voltage DC output terminals of hybrid power electronic transformer 100A and hybrid power electronic transformer 100B are connected through a common DC bus.

[0041] In hybrid power electronic transformers, the energy harvesting module VP can achieve low-voltage DC voltage within a certain range [V]. min V max It allows for flexible settings and adjustments, and features a power-voltage droop characteristic with a droop slope of K.

[0042] By adjusting the droop characteristics of the energy harvesting module VP, DC interconnection power flow control and distribution between different hybrid power electronic transformers can be achieved.

[0043] For example, when two hybrid power electronic transformers, 100A and 100B, are interconnected, Among them, the maximum output voltage of the 100A hybrid power electronic transformer is V. Imax The droop slope is K I The active power is P I The output DC voltage is Vo. I =V Imax -K IP I .

[0044] Similarly, the output DC voltage of the hybrid power electronic transformer 100B is Vo. II =V IImax -K II P II Among them, Vo II This represents the output DC voltage, V, of the hybrid power electronic transformer 100B. IImax K represents the maximum output voltage value of the hybrid power electronic transformer 100B. II P represents the sag slope of the hybrid power electronic transformer 100B. II This indicates the active power of the hybrid power electronic transformer 100B.

[0045] And V Imax =V IImax K I =K II (When the circuit parameters and algorithm parameters of the AC / DC power module VP are consistent), therefore, to achieve P I and P II The power distribution between the two only requires adjusting their respective direct output voltages Vo. I Vo II That can be achieved.

[0046] In this embodiment, the low-voltage DC output interface of the hybrid power electronic transformer can also be used for DC interconnection between different hybrid power electronic transformers to achieve mutual support of active power flow between them.

[0047] For ease of understanding, the specific process of the embodiments of this application is described below. Please refer to [link / reference]. Figure 6 One embodiment of the voltage regulation method in this application can be applied to any of the above-mentioned hybrid power electronic transformers or AC / DC hybrid power supply systems. The voltage regulation method includes: 601. Obtain the actual output parameters of the low-voltage AC output terminal.

[0048] Specifically, obtain the actual voltage amplitude V1 and the corresponding actual phase C1, or the actual power factor angle, of each phase of the low-voltage AC output terminal (LR11 / LR21 / LR31).

[0049] 602. Based on the difference between the actual output parameters and the target output parameters and the preset control function, the parameter modulation signal is obtained.

[0050] Optionally, this embodiment includes two closed-loop control loops: a voltage amplitude closed-loop control loop and a phase closed-loop control loop. Specifically, a voltage amplitude modulation signal is obtained based on the voltage amplitude difference between the actual voltage amplitude V1 of each phase and the target voltage amplitude and a preset first control function; a phase modulation signal is obtained based on the phase difference between the actual phase C1 of each phase and the target phase and a preset second control function.

[0051] 603. Adjust the output voltage of the low-voltage AC output terminal according to the parameter modulation signal.

[0052] Specifically, the output voltage of the low-voltage AC output terminal is adjusted according to the voltage amplitude modulation signal V0 and the phase modulation signal C0. In this embodiment, the voltage amplitude modulation signal and the phase modulation signal are combined to form a modulation signal vector [V0, C0]. The modulation signal vector [V0, C0] is compared with the carrier signal in the controller to output the drive signal of the power device in the voltage control module VC. By changing the duty cycle of the power device, the output voltage of the low-voltage regulating winding LR12 / LR22 / LR32 is adjusted and coupled to the high-voltage compensation regulating winding, thereby realizing the adjustment and flexible control of the output voltage of the low-voltage AC LR11 / LR21 / LR31.

[0053] For example, with Figure 7 The voltage regulation of a single-phase equivalent circuit will be used as an example for illustration: Assuming the turns ratio of the primary and secondary windings is n1, the turns ratio of the high-voltage compensation winding and the low-voltage regulating winding is n2, and the input grid voltage of the hybrid transformer is U... H The primary winding voltage is U 1H The voltage of the high-voltage compensation winding is U 2H The voltage output of the voltage control module VC, connected to the low-voltage regulating winding, is U. 2L If the secondary winding voltage is U1, then: UH=U 1H +U 2H , U1=n1*U 1H =n1*(U H -U 2H ) = n1 (U H -n2*U 2L ) As can be seen from the above formula, changing the output voltage U of the voltage control module VC... 2L This allows you to adjust the voltage of the low-voltage secondary output winding.

[0054] In this embodiment, a parameter modulation signal is obtained by the difference between the actual output parameters and the target output parameters of the low-voltage AC output terminal and a preset control function. The output voltage of the low-voltage AC output terminal is adjusted according to the parameter modulation signal. The control signal or the drive signal of the power device directly controls the energy harvesting module VP and the voltage control module VC. The output voltages of the energy harvesting module VP and the voltage control module VC are directly superimposed on the windings of the transformer body. The low-voltage three-phase output voltage is finally stabilized through magnetic circuit coupling formed by the magnetic core between the windings.

[0055] The hybrid power electronic transformer in this application has been described above. The voltage regulation device in this application is described below. Please refer to [link / reference]. Figure 8 One embodiment of the voltage regulation device in this application includes: Acquisition unit 801 is used to acquire the actual output parameters of the low-voltage AC output terminal; The determining unit 802 is used to obtain the parameter modulation signal based on the difference between the actual output parameter and the target output parameter and the preset control function; The feedback adjustment unit 803 is used to adjust the output voltage of the low-voltage AC output terminal according to the parameter modulation signal.

[0056] In this embodiment, a parameter modulation signal is obtained by the difference between the actual output parameters and the target output parameters of the low-voltage AC output terminal and a preset control function. The output voltage of the low-voltage AC output terminal is adjusted according to the parameter modulation signal. The control signal or the drive signal of the power device directly controls the energy harvesting module VP and the voltage control module VC. The output voltages of the energy harvesting module VP and the voltage control module VC are directly superimposed on the windings of the transformer body. The low-voltage three-phase output voltage is finally stabilized through magnetic circuit coupling formed by the magnetic core between the windings.

[0057] above Figure 8 The voltage regulation device in this application is described in detail from the perspective of modular functional entities. The hybrid power electronic transformer can control its output voltage through a hybrid power electronic converter control system. The hybrid power electronic converter control system in this application is described in detail below from the perspective of hardware processing. Figure 9 and Figure 10 The hybrid power electronic converter control system provided in this application includes a controller, power electronic circuits, and a winding transformer; The voltage of the winding transformer is regulated by the power electronic circuit controlled by the controller, and the hybrid power electronic converter control system executes the above voltage regulation method.

[0058] Specifically, the controller acquires the three-phase high-voltage input parameters and the three-phase low-voltage output parameters, and adjusts the winding transformer of the energy harvesting module VP and the voltage control module VC through the built-in regulation logic.

[0059] Reference Figure 11 The control principle of the controller in this application is explained as follows: In this embodiment, the amplitude and phase of the actual output voltages U1 / U2 / U3 of the three-phase secondary windings at the low-voltage AC output terminal are used as feedback inputs I1, I2, and I3 for system control. Here, I represents the actual voltage amplitude and actual phase as feedback input parameters, I1 represents the feedback input parameter of the first phase, I2 represents the feedback input parameter of the second phase, and I3 represents the feedback input parameter of the third phase.

[0060] The target values ​​for the output voltage control of the three-phase low-voltage output secondary winding V2 / V3 / V4, the target values ​​for the phase control of the energy harvesting AC / DC module VP C1 / C2 / C3, and the target values ​​for the phase control of the voltage control DC / AC module VC C4 / C5 / C6 are used as the target settings for system control, which are also the corresponding target values ​​for power factor angle control. This embodiment does not limit the method for determining the target values.

[0061] The output control quantities O1 / O2 / O3 of the hybrid power electronic converter control system are control signals for the energy harvesting AC / DC module VP or drive signals for the power devices, while the output control quantities O4 / O5 / O6 are control signals for the voltage control DC / AC module VC or drive signals for the power devices.

[0062] The control signals or drive signals O1 / O2 / O3 of the power devices directly control the power devices of the conversion circuit inside the energy harvesting module VP, and the control signals or drive signals O4 / O5 / O6 of the power devices directly control the power devices of the conversion circuit inside the voltage control module VC. By changing the duty cycle of the drive signals, the DC voltage, reactive component of AC current and negative sequence component of the energy harvesting module VP are controlled, thereby achieving stable control of DC voltage, power factor compensation of the low-voltage AC output port of the hybrid transformer and compensation of unbalanced current component. By changing the duty cycle of the drive signals, the output voltage amplitude and phase of the voltage control module VC are directly coupled and superimposed on the windings HR12 / HR22 / HR32 of the transformer body. The windings are ultimately coupled through the magnetic circuit formed by the magnetic core to achieve stable control of the low-voltage three-phase output voltage LR11 / LR21 / LR31.

[0063] The voltage regulation control principle of the DC / AC control module VC is as follows: Figure 12As shown, a three-phase voltage independent closed-loop control method is adopted. The amplitude U and phase of the actual voltage output of each phase are used as the feedback input of the control loop. The amplitude and phase C4 / C5 / C6 of the target value V of the low-voltage output secondary winding are used as the target input of the control loop. The output signal of the closed-loop control of each phase voltage is O4 / O5 / O6. This signal is used as the drive signal of the VC power device of the voltage control DC / AC module. The stability regulation and control of the secondary output winding voltage of each phase is adjusted by changing the duty cycle of the drive signal.

[0064] This application also provides a computer-readable storage medium, which can be a non-volatile computer-readable storage medium or a volatile computer-readable storage medium, storing instructions that, when executed on a computer, cause the computer to perform the steps of a voltage regulation method.

[0065] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0066] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0067] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A hybrid power electronic transformer, characterized in that, include: Winding transformers and power electronic circuits; The winding transformer is used for voltage level transformation, and the power electronic circuit is used for bidirectional voltage regulation. The winding transformer includes a magnetic core, and a primary winding, a first secondary winding, and a second secondary winding disposed on both sides of the magnetic core. The primary winding is connected to the high-voltage AC input terminal, and the first secondary winding is connected to the low-voltage AC output terminal. The second secondary winding is connected to the first terminal of the power electronic circuit, the second terminal of the power electronic circuit is connected to the low-voltage AC output terminal, and the third terminal of the power electronic circuit is connected to the low-voltage DC output terminal.

2. The hybrid power electronic transformer according to claim 1, characterized in that, The power electronic circuit includes a voltage control module and an energy harvesting module; The voltage control module and the energy harvesting module each have an AC port and a DC port; The AC port of the voltage control module is connected to the second secondary winding; The AC port of the energy harvesting module is connected to the first secondary winding; The DC port of the voltage control module is connected to the DC port of the energy harvesting module and is also connected to the low-voltage DC output terminal.

3. The hybrid power electronic transformer according to claim 1, characterized in that, The primary winding includes a first primary winding and a second primary winding connected in series; The first primary winding and the first secondary winding form a low-voltage AC output circuit; The second primary winding and the second secondary winding form a low-voltage AC compensation circuit.

4. The hybrid power electronic transformer according to claim 3, characterized in that, The first primary winding includes a three-phase primary winding, and the second primary winding includes a three-phase compensation winding. Each phase primary winding and the corresponding compensation winding are connected in series to form a delta connection structure and are connected to the three-phase interface of the high-voltage AC input terminal.

5. An AC / DC hybrid power supply system, characterized in that, It includes the target power grid, AC load, DC source-grid-load-storage, and at least one hybrid power electronic transformer as described in any one of claims 1-4; The target power grid is connected to the high-voltage AC input terminal of the hybrid power electronic transformer; The low-voltage DC output terminal of the hybrid power electronic transformer is connected to the DC power grid and its energy storage via a common DC bus. The low-voltage AC output terminal of the hybrid power electronic transformer is connected to the AC load via a common AC bus.

6. The AC / DC hybrid power supply system according to claim 5, characterized in that, The target power grid includes a first power grid and a second power grid; The first power grid is connected to the high-voltage AC input terminal of a hybrid power electronic transformer, and the second power grid is connected to the high-voltage AC input terminal of another hybrid power electronic transformer. The low-voltage DC output terminals of each of the hybrid power electronic transformers are connected via a common DC bus.

7. A voltage regulation method, characterized in that, The voltage regulation method, applied to the hybrid power electronic transformer as described in any one of claims 1-4 or the AC / DC hybrid power supply system as described in any one of claims 5-6, comprises: Obtain the actual output parameters of the low-voltage AC output terminal; The parameter modulation signal is obtained based on the difference between the actual output parameters and the target output parameters and the preset control function; The output voltage of the low-voltage AC output terminal is adjusted according to the parameter modulation signal.

8. A voltage regulating device, characterized in that, The voltage regulating device, applied to the hybrid power electronic transformer as described in any one of claims 1-4 or the AC / DC hybrid power supply system as described in any one of claims 5-6, comprises: The acquisition unit is used to acquire the actual output parameters of the low-voltage AC output terminal. The determining unit is used to obtain the parameter modulation signal based on the difference between the actual output parameter and the target output parameter and a preset control function; The feedback adjustment unit is used to adjust the output voltage of the low-voltage AC output terminal according to the parameter modulation signal.

9. A hybrid power electronic converter control system, characterized in that, The hybrid power electronic converter control system includes a controller, power electronic circuits, and winding transformers; The controller controls the power electronic circuit to regulate the voltage of the winding transformer, and the hybrid power electronic converter control system executes the voltage regulation method as described in claim 7.

10. A computer-readable storage medium storing instructions thereon, characterized in that, The instruction, when read and executed, performs the voltage regulation method as described in claim 7.

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