Power quality control system

Abstract

The utility model provides an electric energy quality control system, and belongs to the technical field of power electronics. The electric energy quality control system comprises a transformer module, a first alternating current-direct current conversion unit, a second alternating current-direct current conversion unit and a third alternating current-direct current conversion unit, one end of the transformer module is used for accessing a three-phase power grid, and the other end of the transformer module is connected with an alternating current port of the third alternating current-direct current conversion unit; an AC port of the first AC-DC conversion unit and an AC port of the second AC-DC conversion unit are connected to a three-phase power grid, and a DC port of the first AC-DC conversion unit is connected with a DC port of the second AC-DC conversion unit and the third AC-DC conversion unit to provide DC. According to the invention, the algorithm difficulty of the power converter can be reduced, and the unified management capability of the electric energy quality control system can be improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and more particularly, to a power quality control system. Background Art

[0002] In the field of power quality management, common power quality management devices include shunt compensators or filters, series compensators or filters, etc. Among them, shunt compensators mainly compensate for harmonic and reactive currents on the load side, and can also manage three-phase active power imbalance in specific scenarios to achieve three-phase energy transfer and ensure approximate balance of three-phase loads; series compensators mainly compensate for voltage, including fundamental voltage and harmonic voltage. However, both of the above two compensators or filters have their own advantages and disadvantages. Therefore, the combined use of the two compensators has become a unified power quality controller (UPQC), such as the currently common series-parallel active power compensator or filter. This unified power quality controller can compensate both current and voltage, with rich functions.

[0003] In related technologies, the UPQC system structure usually consists of two back-to-back power converters. One end of the power converter is connected to the power grid, and the other end is connected in series to the power grid through a transformer, forming a DC bus inside the UPQC system. Among them, the power converter directly connected to the power grid constitutes a shunt current compensator, and the power converter connected in series to the power grid through a transformer constitutes a series voltage compensator. The DC bus in the UPQC system is controlled by the shunt current compensator, which can not only achieve current compensation but also maintain the stability of the DC bus through active current. In addition, the power converter not only needs to provide capacity for three-phase current but also needs to provide energy for the inverter of the subsequent circuit bus, so that the power level of the power converter needs to be greater than the power level of the inverter in the subsequent circuit.

[0004] However, when performing power quality management based on related technologies, different power levels will result in complex algorithms for power converters and significant algorithm differences, which is not conducive to the module design and batch management of the UPQC system. Summary of the Utility Model

[0005] The purpose of this application is to provide a power quality control system, which can achieve the effects of reducing the algorithm difficulty of power converters and improving the unified management ability of the power quality control system.

[0006] The embodiments of this application are implemented as follows:

[0007] In the first aspect of the embodiments of the present application, a power quality control system is provided. The power quality control system includes: a transformer module, a first AC-DC conversion unit, a second AC-DC conversion unit, and a third AC-DC conversion unit;

[0008] One end of the transformer module is used to access the three-phase power grid, and the other end of the transformer module is connected to the AC port of the third AC-DC conversion unit;

[0009] The AC ports of the first AC-DC conversion unit and the second AC-DC conversion unit are both connected to the three-phase power grid. The DC ports of the first AC-DC conversion unit are respectively connected to the DC ports of the second AC-DC conversion unit and the third AC-DC conversion unit to provide DC power.

[0010] As a possible implementation, the transformer module includes: a first transformer, a second transformer, and a third transformer;

[0011] One end of the first transformer, one end of the second transformer, and one end of the third transformer are respectively connected to each phase of the three-phase power grid in one-to-one correspondence;

[0012] The other end of the first transformer, the other end of the second transformer, and the other end of the third transformer are respectively connected to the AC ports of each phase of the third AC-DC conversion unit in one-to-one correspondence.

[0013] As a possible implementation, the first AC-DC conversion unit includes: a signal end and a DC port;

[0014] The signal end of the first AC-DC conversion unit is connected to the signal input end of the third AC-DC conversion unit, and the signal end is used to provide a phase synchronization signal to the third AC-DC conversion unit;

[0015] The DC ports of the first AC-DC conversion unit are respectively connected to the DC ports of the second AC-DC conversion unit and the third AC-DC conversion unit to provide DC power.

[0016] As a possible implementation, the power quality control system further includes: a switch module. The AC port of the third AC-DC conversion unit includes: a first output end, a second output end, a third output end, and a neutral line end;

[0017] The first output end, the second output end, and the third output end of the third AC-DC conversion unit are all connected to the input end of the switch module. The first output end of the third AC-DC conversion unit is connected to the other end of the first transformer, the second output end of the third AC-DC conversion unit is connected to the other end of the second transformer, and the third output end of the third AC-DC conversion unit is connected to the other end of the third transformer;

[0018] The neutral line terminals of the third AC-DC conversion unit are respectively connected to the output terminals of the switch module, the other ends of the first transformer, the other ends of the second transformer, and the other ends of the third transformer.

[0019] As a possible implementation, the switch module includes: a first switch unit, a second switch unit, and a third switch unit. The third AC-DC conversion unit further includes: a signal control terminal;

[0020] The input terminal of the first switch unit is connected to the first output terminal of the third AC-DC conversion unit, the output terminal of the first switch unit is connected to the neutral line terminal of the third AC-DC conversion unit, and the control terminal of the first switch unit is connected to the signal control terminal of the third AC-DC conversion unit;

[0021] The input terminal of the second switch unit is connected to the second output terminal of the third AC-DC conversion unit, the output terminal of the second switch unit is connected to the neutral line terminal of the third AC-DC conversion unit, and the control terminal of the second switch unit is connected to the signal control terminal of the third AC-DC conversion unit;

[0022] The input terminal of the third switch unit is connected to the third output terminal of the third AC-DC conversion unit, the output terminal of the third switch unit is connected to the neutral line terminal of the third AC-DC conversion unit, and the control terminal of the third switch unit is connected to the signal control terminal of the third AC-DC conversion unit.

[0023] As a possible implementation, the first switch unit includes: a first electronic switch; the second switch unit includes: a second electronic switch; the third switch unit includes: a third electronic switch;

[0024] The input terminal of the first electronic switch is connected to the first output terminal of the third AC-DC conversion unit, the input terminal of the second electronic switch is connected to the second output terminal of the third AC-DC conversion unit, and the input terminal of the third electronic switch is connected to the third output terminal of the third AC-DC conversion unit;

[0025] The output terminals of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the neutral line terminal of the third AC-DC conversion unit, and the control terminals of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the signal control terminal of the third AC-DC conversion unit.

[0026] As a possible implementation, the first switch unit includes: a first electronic switch and a first mechanical switch, the second switch unit includes: a second electronic switch and a second mechanical switch, the third switch unit includes: a third electronic switch and a third mechanical switch;

[0027] The input terminal of the first electronic switch and the input terminal of the first mechanical switch are both connected to the first output terminal of the third AC-DC conversion unit. The input terminal of the second electronic switch and the input terminal of the second mechanical switch are both connected to the second output terminal of the third AC-DC conversion unit. The input terminal of the third electronic switch and the input terminal of the third mechanical switch are both connected to the third output terminal of the third AC-DC conversion unit;

[0028] The output terminal of the first electronic switch, the output terminal of the first mechanical switch, the output terminal of the second electronic switch, the output terminal of the second mechanical switch, the output terminal of the third electronic switch, and the output terminal of the third mechanical switch are all connected to the neutral line terminal of the third AC-DC conversion unit;

[0029] The control terminals of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the signal control terminal of the third AC-DC conversion unit. The control terminals of the first mechanical switch, the second mechanical switch, and the third mechanical switch are all connected to an external drive circuit.

[0030] As a possible implementation, the above power quality control system further includes: an energy storage module;

[0031] The output terminal of the energy storage module is connected to the DC port of the second AC-DC conversion unit.

[0032] As a possible implementation, the above power quality control system further includes: a detection and monitoring module;

[0033] The detection and monitoring module is communicatively connected to the transformer module, the first AC-DC conversion unit, the second AC-DC conversion unit, and the third AC-DC conversion unit respectively.

[0034] As a possible implementation, the above power quality control system further includes: at least one load;

[0035] The load is connected to the three-phase power grid;

[0036] The third AC-DC conversion unit is used to output a three-phase compensation voltage to the transformer module;

[0037] The second AC-DC conversion unit is used to adjust the output power of the three-phase power grid.

[0038] The beneficial effects of the embodiments of the present application include:

[0039] A power quality control system provided by an embodiment of the present application forms a power quality control system through a transformer module, a first AC-DC conversion unit, a second AC-DC conversion unit, and a third AC-DC conversion unit. One end of the transformer module is used to access the phase voltages of a three-phase power grid, and the other end of the transformer module is connected to the AC port of the third AC-DC conversion unit. The transformer module compensates the phase output voltages of the three-phase power grid under the action of the signal output at the AC port of the third AC-DC conversion unit; the AC port of the first AC-DC conversion unit is connected to the three-phase power grid. The first AC-DC conversion unit accesses the alternating current of each phase of the three-phase power grid through the AC port, and converts the received alternating current into a corresponding direct current based on the AC-DC conversion characteristics of the first AC-DC conversion unit. The first AC-DC conversion unit provides a constant DC signal to the second AC-DC conversion unit and the third AC-DC conversion unit through the DC port; the AC port of the second AC-DC conversion unit is directly connected to the three-phase power grid. The second AC-DC conversion unit adjusts the phase output power of the three-phase power grid through the AC port under the action of the DC signal provided by the first AC-DC conversion unit; the third AC-DC conversion unit conveys the voltage compensation value corresponding to each phase voltage to the transformer module through the AC port under the action of the DC signal output by the first AC-DC conversion unit. Among them, the first AC-DC conversion unit, the second AC-DC conversion unit, and the third AC-DC conversion unit only serve as the execution members of the power quality control system, which can effectively reduce the algorithm difficulty of the power converter. In this way, the algorithm difficulty of the power converter can be reduced, and the unified management ability of the power quality control system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic structural diagram of the first power quality control system provided by an embodiment of the present application;

[0042] Figure 2 It is a schematic structural diagram of a transformer module provided by an embodiment of the present application;

[0043] Figure 3 It is a schematic structural diagram of the second power quality control system provided by an embodiment of the present application;

[0044] Figure 4 It is a schematic structural diagram of the first switch module provided by an embodiment of the present application;

[0045] Figure 5 Schematic diagram of the second switch module provided by the embodiment of the present application;

[0046] Figure 6 Schematic diagram of the third switch module provided by the embodiment of the present application;

[0047] Figure 7 Schematic diagram of the third power quality control system provided by the embodiment of the present application;

[0048] Figure 8 Schematic diagram of the fourth power quality control system provided by the embodiment of the present application;

[0049] Figure 9 Schematic diagram of the fifth power quality control system provided by the embodiment of the present application.

[0050] Description of the drawings: 10: Power quality control system; 101: Transformer module; 1011: First transformer; 1012: Second transformer; 1013: Third transformer; 102: First AC-DC conversion unit; 103: Second AC-DC conversion unit; 104: Third AC-DC conversion unit; 105: Switch module; 1051: First switch unit; 511: First electronic switch; 512: First mechanical switch; 1052: Second switch unit; 521: Second electronic switch; 522: Second mechanical switch; 1053: Third switch unit; 531: Third electronic switch; 532: Third mechanical switch; 106: Energy storage module; 107: Detection and monitoring module; 108: Load. Detailed implementation manners

[0051] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. The components of the embodiments of the present application described and illustrated herein generally can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but is merely representative of selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0053] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0054] In the description of the present application, it should be noted that the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance. It should also be noted that unless otherwise clearly specified and defined, the terms "arranged", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0055] Currently, a power quality control system is usually composed of two-stage back-to-back power converters. One end of the power converter is connected to the power grid, and the other end is connected in series to the power grid through a transformer, so that a DC bus is formed inside the power quality control system. Among them, the power converter directly connected to the power grid constitutes a shunt current compensator, and the power converter connected in series to the power grid through a transformer constitutes a series voltage compensator. The DC bus in the power quality control system is controlled by the shunt current compensator, which can not only achieve current compensation but also maintain the stability of the DC bus through the active current. However, in this power quality control system, the power converter not only needs to provide the occupied capacity for the three-phase current but also needs to provide energy for the inverter of the subsequent circuit bus, which results in complex algorithms for the power converter and large algorithm differences, and is not conducive to the module design and batch management of the UPQC system.

[0056] Therefore, an embodiment of the present application provides a power quality control system, which is composed of a transformer module, a first AC-DC conversion unit, a second AC-DC conversion unit, and a third AC-DC conversion unit. Among them, the first AC-DC conversion unit provides a DC signal and a phase synchronization signal to the second AC-DC conversion unit and the third AC-DC conversion unit based on the output signals of each phase of the three-phase power grid. The second AC-DC conversion unit adjusts the output power of the three-phase power grid under the action of the DC signal. The third AC-DC conversion unit outputs a three-phase voltage compensation value to the transformer module under the action of the DC signal and the phase synchronization signal. In this way, the algorithm difficulty of the power converter can be reduced, and the unified management ability of the power quality control system can be improved.

[0057] The power quality control system provided by the embodiment of the present application will be explained in detail below with reference to the accompanying drawings.

[0058] Figure 1 is a schematic structural diagram of the first power quality control system provided by the present application. See Figure 1, an embodiment of the present application provides a power quality control system 10, which includes: a transformer module 101, a first AC-DC conversion unit 102, a second AC-DC conversion unit 103, and a third AC-DC conversion unit 104.

[0059] One end of the transformer module 101 is used to connect to a three-phase power grid, and the other end of the transformer module 101 is connected to the AC port of the third AC-DC conversion unit 104.

[0060] The AC ports of the first AC-DC conversion unit 102 and the second AC-DC conversion unit 103 are both connected to the three-phase power grid. The DC port of the first AC-DC conversion unit 102 is respectively connected to the DC port of the second AC-DC conversion unit 103 and the third AC-DC conversion unit 104 to provide DC power.

[0061] Optionally, the first AC-DC conversion unit 102, the second AC-DC conversion unit 103, and the third AC-DC conversion unit 104 can all be implemented by a power converter or an AC-DC converter. The present application does not make specific limitations in this regard.

[0062] Optionally, the first AC-DC conversion unit 102 obtains alternating current from the three-phase power grid through the AC port. The first AC-DC conversion unit 102 converts the alternating current output by the three-phase power grid into corresponding direct current based on its own AC-DC conversion characteristics. The DC port of the first AC-DC conversion unit 102 can be used as the DC bus inside the power quality control system 10. The first AC-DC conversion unit 102 provides a constant DC signal to the second AC-DC conversion unit 103 and the third AC-DC conversion unit 104 through the DC port.

[0063] Optionally, the second AC-DC conversion unit 103 can be implemented by a power converter. The AC port of the second AC-DC conversion unit 103 can include multiple AC output ports. The second AC-DC conversion unit 103 can compensate the output power of each phase of the three-phase power grid through each phase AC port.

[0064] Optionally, the DC port of the second AC-DC conversion unit 103 is used to connect to the DC signal provided by the first AC-DC conversion unit 102. The AC port of the second AC-DC conversion unit 103 is directly connected to the three-phase power grid. The second AC-DC conversion unit 103 compensates the output power of each phase of the three-phase power grid through the AC port. The signal output by the AC port of the second AC-DC conversion unit 103 is the current compensation value corresponding to the alternating current of each phase of the three-phase power grid.

[0065] Optionally, the third AC-DC conversion unit 104 receives the direct current provided by the first AC-DC conversion unit 102, and the third AC-DC conversion unit 104 outputs voltage compensation values corresponding to the output voltages of each phase of the three-phase power grid to each transformer in the transformer module 101 through the AC port of the third AC-DC conversion unit 104 based on the received direct current.

[0066] In the embodiment of the present application, a power quality control system is constituted by a transformer module, a first AC-DC conversion unit, a second AC-DC conversion unit, and a third AC-DC conversion unit. One end of the transformer module is used to access the voltages of each phase of the three-phase power grid, and the other end of the transformer module is connected to the AC port of the third AC-DC conversion unit. The transformer module compensates the output voltages of each phase of the three-phase power grid under the action of the signal output from the AC port of the third AC-DC conversion unit; the AC port of the first AC-DC conversion unit is connected to the three-phase power grid. The first AC-DC conversion unit accesses the alternating current of each phase of the three-phase power grid through the AC port, and converts the received alternating current into the corresponding direct current based on the AC-DC conversion characteristics of the first AC-DC conversion unit. The first AC-DC conversion unit provides a constant DC signal to the second AC-DC conversion unit and the third AC-DC conversion unit through the DC port; the AC port of the second AC-DC conversion unit is directly connected to the three-phase power grid. The second AC-DC conversion unit adjusts the output power of each phase of the three-phase power grid through the AC port under the action of the DC signal provided by the first AC-DC conversion unit; the third AC-DC conversion unit outputs the voltage compensation values corresponding to each phase voltage to the transformer module through the AC port under the action of the DC signal output by the first AC-DC conversion unit. Among them, the first AC-DC conversion unit, the second AC-DC conversion unit, and the third AC-DC conversion unit only serve as the execution members of the power quality control system, which can effectively reduce the algorithm difficulty of the power converter. In this way, the algorithm difficulty of the power converter can be reduced, and the unified management ability of the power quality control system can be improved.

[0067] Figure 2 The following is a schematic structural diagram of a transformer module provided by the present application. Refer to Figure 2 In the embodiment of the present application, the transformer module 101 in the power quality control system 10 includes: a first transformer 1011, a second transformer 1012, and a third transformer 1013.

[0068] Optionally, the transformer module 101 is composed of multiple transformers connected in parallel. The turns ratios of the transformers in the transformer module 101 may be the same or different, and the present application does not make specific limitations thereon. Each transformer in the transformer module 101 is used to transmit the voltages of the respective phases of the three-phase power grid and compensate the voltages of the respective phases of the three-phase power grid. Taking the transformer module 101 including three transformers as an example in the present application, the transformer module 101 includes a first transformer 1011, a second transformer 1012, and a third transformer 1013.

[0069] Optionally, each transformer in the transformer module 101 compensates the voltages of the respective phases of the three-phase power grid based on the voltage compensation values sent by the third AC-DC conversion unit 104, and the transformer module 101 compensates the voltages of the respective phases of the three-phase power grid based on the coupling effect of each transformer.

[0070] One end of the first transformer 1011, one end of the second transformer 1012, and one end of the third transformer 1013 are respectively connected to the respective phases of the three-phase power grid in one-to-one correspondence.

[0071] Optionally, one end of the first transformer 1011, one end of the second transformer 1012, and one end of the third transformer 1013 are all used to access the three-phase power grid. For example, one end of the first transformer 1011 accesses the A-phase voltage of the three-phase power grid, one end of the second transformer 1012 accesses the B-phase voltage of the three-phase power grid, and one end of the third transformer 1013 accesses the C-phase voltage of the three-phase power grid. The present application does not make specific limitations thereon.

[0072] Optionally, the turns ratios of the first transformer 1011, the second transformer 1012, and the third transformer 1013 may be the same or different, and the present application does not make specific limitations thereon.

[0073] The other end of the first transformer 1011, the other end of the second transformer 1012, and the other end of the third transformer 1013 are respectively connected to the respective phase AC ports of the third AC-DC conversion unit 104 in one-to-one correspondence.

[0074] Optionally, the other end of the first transformer 1011, the other end of the second transformer 1012, and the other end of the third transformer 1013 are respectively connected to the respective phase AC ports of the third AC-DC conversion unit 104, and are used to receive the voltage compensation values corresponding to the voltages of the respective phases output by the third AC-DC conversion unit 104.

[0075] Exemplarily, one end of the first transformer 1011 is connected to the A-phase voltage of the three-phase power grid, and the other end of the first transformer 1011 receives the voltage compensation value corresponding to the A-phase voltage through the AC port of the third AC-DC conversion unit 104; one end of the second transformer 1012 is connected to the B-phase voltage of the three-phase power grid, and the other end of the second transformer 1012 receives the voltage compensation value corresponding to the B-phase voltage through the AC port of the third AC-DC conversion unit 104; one end of the third transformer 1013 is connected to the C-phase voltage of the three-phase power grid, and the other end of the third transformer 1013 receives the voltage compensation value corresponding to the C-phase voltage through the AC port of the third AC-DC conversion unit 104.

[0076] Optionally, one end of each transformer in the transformer module 101 is used to connect to the output voltages of the respective phases of the three-phase power grid, and the other end of each transformer in the transformer module 101 is used to connect to the voltage compensation values of the respective phases output from the AC port of the third AC-DC conversion unit 104. The transformer module 101 performs voltage compensation on the output voltages of the respective phases of the three-phase power grid based on the voltage compensation values of the respective phases output by the third AC-DC conversion unit 104 and the voltage transformation ratios of the respective transformers.

[0077] As an optional implementation manner, refer to Figure 2 , the first AC-DC conversion unit 102 in the power quality control system 10 provided by the embodiments of the present application includes: a signal terminal and a DC port.

[0078] The signal terminal of the first AC-DC conversion unit 102 is connected to the signal input terminal of the third AC-DC conversion unit 104, and the signal terminal is used to provide a phase synchronization signal to the third AC-DC conversion unit 104.

[0079] Optionally, the first AC-DC conversion unit 102 obtains the phase signals corresponding to the output voltages of the respective phases of the three-phase power grid from the three-phase power grid via the AC port, and the first AC-DC conversion unit 102 transmits the phase signals corresponding to the output voltages of the respective phases of the three-phase power grid to the third AC-DC conversion unit 104 via the signal terminal. The phase synchronization signal is used to indicate a signal synchronized with the phases of the output voltages of the respective phases of the three-phase power grid.

[0080] Optionally, under the action of the phase synchronization signal, the third AC-DC conversion unit 104 can synchronously output the voltage compensation values corresponding to the output voltages of the respective phases.

[0081] The DC port of the first AC-DC conversion unit 102 is respectively connected to the DC port of the second AC-DC conversion unit 103 and the third AC-DC conversion unit 104 to provide DC power.

[0082] Optionally, the DC port of the first AC-DC conversion unit 102 serves as the internal DC bus of the power quality control system 10, and the first AC-DC conversion unit 102 provides a constant DC signal to the second AC-DC conversion unit 103 and the third AC-DC conversion unit 104 via the DC port.

[0083] Figure 3 FIG. 2 is a schematic structural diagram of the second power quality control system provided by the present application. Refer to Figure 3 In an embodiment of the present application, a power quality control system 10 further includes: a switch module 105. The AC port of the third AC-DC conversion unit 104 includes: a first output terminal, a second output terminal, a third output terminal, and a neutral line terminal N1.

[0084] Optionally, the power quality control system 10 not only includes a three-phase power grid, but also adds a neutral line N, so that the power quality control system 10 forms a three-phase four-wire circuit topology structure.

[0085] Optionally, the AC port of the third AC-DC conversion unit 104 includes: a first output terminal, a second output terminal, a third output terminal, and a neutral line terminal N1. Among them, the first output terminal, the second output terminal, and the third output terminal are used to separately output the voltage compensation values corresponding to the phase output voltages of the three-phase power grid, and the neutral line terminal N1 is adapted to the three-phase four-wire structure of the power quality control system 10.

[0086] Optionally, the AC port of the third AC-DC conversion unit 104 includes multiple AC output ports such as a first output terminal, a second output terminal, and a third output terminal, which are used to respectively output the voltage compensation values corresponding to the phase voltages, so that the compensation processes of the phase voltages of the three-phase power grid do not interfere with each other.

[0087] The first output terminal, the second output terminal, and the third output terminal of the third AC-DC conversion unit 104 are all connected to the input terminal of the switch module 105. The first output terminal of the third AC-DC conversion unit 104 is connected to the other end of the first transformer 1011. The second output terminal of the third AC-DC conversion unit 104 is connected to the other end of the second transformer 1012. The third output terminal of the third AC-DC conversion unit 104 is connected to the other end of the third transformer 1013.

[0088] The neutral line terminal of the third AC-DC conversion unit 104 is respectively connected to the output terminal of the switch module 105, the other end of the first transformer 1011, the other end of the second transformer 1012, and the other end of the third transformer 1013.

[0089] Optionally, the first output terminal, the second output terminal, and the third output terminal of the third AC-DC conversion unit 104 lead out two parallel branches of the transformer module 101 and the switch module 105. Among them, the third AC-DC conversion unit 104 and each transformer in the transformer module 101 form a complete voltage compensation circuit, and the third AC-DC conversion unit 104 and the switch module 105 form a complete bypass circuit. The switch module 105 can cut off the circuit when a fault occurs in the transformer module 101 or the third AC-DC conversion unit 104, ensuring the safety and reliability of the operation of the power quality control system 10.

[0090] Figure 4 FIG. is a schematic structural diagram of the first switch module provided by this application. Refer to Figure 4 In this regard, an embodiment of this application provides a switch module 105 in a power quality control system 10, including: a first switch unit 1051, a second switch unit 1052, and a third switch unit 1053. The third AC-DC conversion unit 104 further includes: a signal control terminal.

[0091] Optionally, the third AC-DC conversion unit 104 issues corresponding control instructions to each switch unit in the switch module 105 via the signal control terminal to control the on and off of each switch unit.

[0092] The input terminal of the first switch unit 1051 is connected to the first output terminal of the third AC-DC conversion unit 104, the output terminal of the first switch unit 1051 is connected to the neutral line terminal of the third AC-DC conversion unit 104, and the control terminal of the first switch unit 1051 is connected to the signal control terminal of the third AC-DC conversion unit 104.

[0093] Optionally, the first switch unit 1051 is used to control the short circuit of the first output terminal of the third AC-DC conversion unit 104, that is, to control the on and off between the first output terminal of the third AC-DC conversion unit 104 and the first transformer 1011. Among them, the first switch unit 1051 is turned on or off under the action of a switch control signal output by the signal control terminal of the third AC-DC conversion unit 104.

[0094] The input terminal of the second switch unit 1052 is connected to the second output terminal of the third AC-DC conversion unit 104, the output terminal of the second switch unit 1052 is connected to the neutral line terminal of the third AC-DC conversion unit 104, and the control terminal of the second switch unit 1052 is connected to the signal control terminal of the third AC-DC conversion unit 104.

[0095] Optionally, the second switch unit 1052 is configured to control the short - circuit of the second output terminal of the third AC - DC conversion unit 104, that is, to control the connection and disconnection between the second output terminal of the third AC - DC conversion unit 104 and the second transformer 1012. Among them, the second switch unit 1052 is turned on or off under the action of the switch control signal output by the signal control terminal of the third AC - DC conversion unit 104.

[0096] The input terminal of the third switch unit 1053 is connected to the third output terminal of the third AC - DC conversion unit 104, the output terminal of the third switch unit 1053 is connected to the neutral line terminal of the third AC - DC conversion unit 104, and the control terminal of the third switch unit 1053 is connected to the signal control terminal of the third AC - DC conversion unit 104.

[0097] Optionally, the third switch unit 1053 is configured to control the short - circuit of the third output terminal of the third AC - DC conversion unit 104, that is, to control the connection and disconnection between the third output terminal of the third AC - DC conversion unit 104 and the third transformer 1013. Among them, the third switch unit 1053 is turned on or off under the action of the switch control signal output by the signal control terminal of the third AC - DC conversion unit 104.

[0098] As an optional implementation manner, Figure 5 is a schematic structural diagram of the second switch module provided by the present application. Refer to Figure 5 , in the switch module 105 provided by the embodiments of the present application, each switch unit is implemented by only one electronic switch, that is, the first switch unit 1051 in the switch module 105 includes: a first electronic switch 511; the second switch unit 1052 includes: a second electronic switch 521; the third switch unit 1053 includes: a third electronic switch 531.

[0099] Optionally, the first electronic switch 511, the second electronic switch 521, and the third electronic switch 531 are all implemented by transistor electronic switches. The first electronic switch 511, the second electronic switch 521, and the third electronic switch 531 can be implemented by PMOS transistors or NMOS transistors. The present application does not make specific limitations in this regard.

[0100] The input terminal of the first electronic switch 511 is connected to the first output terminal of the third AC - DC conversion unit 104, the input terminal of the second electronic switch 521 is connected to the second output terminal of the third AC - DC conversion unit 104, and the input terminal of the third electronic switch 531 is connected to the third output terminal of the third AC - DC conversion unit 104.

[0101] The output terminals of the first electronic switch 511, the output terminals of the second electronic switch 521, and the output terminals of the third electronic switch 531 are all connected to the neutral line terminal of the third AC-DC conversion unit 104, and the control terminals of the first electronic switch 511, the control terminals of the second electronic switch 521, and the control terminals of the third electronic switch 531 are all connected to the signal control terminal of the third AC-DC conversion unit 104.

[0102] As an alternative implementation, Figure 6 This is a schematic structural diagram of the third switch module provided by the present application. Refer to Figure 6 , in each switch unit of another switch module 105 provided by the embodiments of the present application, it is composed of an electronic switch and a mechanical switch. That is, the first switch unit 1051 in the switch module 105 includes: a first electronic switch 511 and a first mechanical switch 512, the second switch unit 1052 includes: a second electronic switch 521 and a second mechanical switch 522, and the third switch unit 1053 includes: a third electronic switch 531 and a third mechanical switch 532.

[0103] Optionally, the first electronic switch 511, the second electronic switch 521, and the third electronic switch 531 are all implemented by electronic transistors, and the first mechanical switch 512, the second mechanical switch 522, and the third mechanical switch 532 can all be implemented by a circuit breaker, a contactor, a trigger, etc. The present application does not make specific limitations on this.

[0104] The input terminal of the first electronic switch 511 and the input terminal of the first mechanical switch 512 are both connected to the first output terminal of the third AC-DC conversion unit 104, the input terminal of the second electronic switch 521 and the input terminal of the second mechanical switch 522 are both connected to the second output terminal of the third AC-DC conversion unit 104, and the input terminal of the third electronic switch 531 and the input terminal of the third mechanical switch 532 are both connected to the third output terminal of the third AC-DC conversion unit 104.

[0105] The output terminals of the first electronic switch 511, the output terminals of the first mechanical switch 512, the output terminals of the second electronic switch 521, the output terminals of the second mechanical switch 522, the output terminals of the third electronic switch 531, and the output terminals of the third mechanical switch 532 are all connected to the neutral line terminal of the third AC-DC conversion unit 104.

[0106] Optionally, the electronic switch and the mechanical switch in each switch unit cooperate to control the on-off of each phase output terminal in the AC port of the third AC-DC conversion unit 104, which can further improve the reliability of the power quality control system 10.

[0107] The control terminals of the first electronic switch 511, the control terminals of the second electronic switch 521, and the control terminals of the third electronic switch 531 are all connected to the signal control terminal of the third AC-DC conversion unit 104. The control terminals of the first mechanical switch 512, the control terminals of the second mechanical switch 522, and the control terminals of the third mechanical switch 532 are all connected to an external drive circuit.

[0108] Optionally, the external drive circuit is used to control the on / off of each mechanical switch in each switch unit. The user can manually trigger the on / off of the external drive circuit based on the working state of the third AC-DC conversion unit 104 to control the on / off of each mechanical switch, which can further improve the reliability of the power quality control system.

[0109] As an alternative implementation Figure 7 For the structural schematic diagram of the third power quality control system provided by this application, see Figure 7 A power quality control system 10 provided by an embodiment of this application further includes: an energy storage module 106.

[0110] The output terminal of the energy storage module 106 is connected to the DC port of the second AC-DC conversion unit 103.

[0111] Optionally, the energy storage module 106 can be implemented by an energy storage battery, a storage battery, etc. The energy storage module 106 in the power quality control system 10 can supply power to the second AC-DC conversion unit 103.

[0112] Optionally, the power quality control system 10 can either include the energy storage module 106 or not. Whether to select the energy storage module 106 in the power quality control system 10 is determined by the actual application scenario of the power quality control system 10, and this application does not make specific limitations on this.

[0113] Optionally, when the power quality control system 10 is configured with the energy storage module 106, the first AC-DC conversion unit 102 in the power quality control system 10 also needs to balance the charge and discharge of the energy storage module 106.

[0114] As an alternative implementation Figure 8 For the structural schematic diagram of the fourth power quality control system provided by this application, see Figure 8 A power quality control system 10 provided by an embodiment of this application further includes: a detection and monitoring module 107.

[0115] The detection and monitoring module 107 is communicatively connected to the transformer module 101, the first AC-DC conversion unit 102, the second AC-DC conversion unit 103, and the third AC-DC conversion unit 104 respectively.

[0116] Optionally, the detection and monitoring module 107 can be implemented by a computer device, a control chip, etc. The detection and monitoring module 107 is used to monitor the DC-side voltage and AC-side voltage of the transformer module 101 in real time. The detection and monitoring module 107 sends control instructions to the first AC-DC conversion unit 102, the second AC-DC conversion unit 103, and the third AC-DC conversion unit 104 based on the real-time detection results of the transformer module 101.

[0117] Optionally, under the action of the control instruction issued by the detection and monitoring module 107, the first AC-DC conversion unit 102 converts the AC signal output by the three-phase power grid into a corresponding DC signal, and provides a constant DC signal to the second AC-DC conversion unit 103 and the third AC-DC conversion unit 104 through the DC port of the first AC-DC conversion unit 102. When the power quality control system 10 is optionally equipped with the energy storage module 106, the first AC-DC conversion unit 102 also regulates the charge balance of the energy storage module 106 under the action of the detection and monitoring module 107. It should be noted that when the power quality control system 10 is optionally equipped with the energy storage module 106, the detection and monitoring module 107 also monitors the charge and discharge of the energy storage module 106 in real time.

[0118] Optionally, the detection and monitoring module 107 is also used to detect the AC signal output from the three-phase power grid to the load side. The detection and monitoring module 107 outputs a control instruction to the second AC-DC conversion unit 103 based on the AC signal on the load side. Under the action of the control instruction sent by the detection and monitoring module 107, the second AC-DC conversion unit 103 adjusts the output power of each phase of the three-phase power grid through the AC port of the second AC-DC conversion unit 103.

[0119] Optionally, the detection and monitoring module 107 issues a voltage compensation instruction to the third AC-DC conversion unit 104 based on the DC-side voltage and AC-side voltage of the transformer module 101 monitored in real time. The third AC-DC conversion unit 104 outputs the voltage compensation value of each phase to the transformer module 101 through the AC port of the third AC-DC conversion unit 104 based on the received voltage compensation instruction. The transformer module 101 compensates the output voltage of each phase of the three-phase power grid based on the received voltage compensation value of each phase, the output voltage of each phase of the three-phase power grid, and the voltage transformation ratio of each transformer.

[0120] As an optional implementation manner, Figure 9 For the structural schematic diagram of the fifth power quality control system provided by this application, see Figure 9 An power quality control system 10 provided by an embodiment of this application further includes: at least one load 108.

[0121] The load 108 is connected to the three-phase power grid.

[0122] Optionally, the AC side of the load 108 is used to connect to a three-phase power grid, and the three-phase power grid after voltage compensation and power compensation supplies power to the load 108.

[0123] The third AC-DC conversion unit 104 is used to output a three-phase compensation voltage to the transformer module 101.

[0124] Optionally, the third AC-DC conversion unit 104 outputs a three-phase compensation voltage to the transformer module 101. The three-phase compensation voltage is used to indicate the voltage compensation value corresponding to the output voltage of each phase of the three-phase power grid. The transformer module 101 performs voltage compensation on the output voltage of each phase of the three-phase power grid based on the three-phase compensation voltage sent by the third AC-DC conversion unit 104.

[0125] The second AC-DC conversion unit 103 is used to regulate the output power of the three-phase power grid.

[0126] Optionally, based on the control instruction issued by the detection and monitoring module 107, the second AC-DC conversion unit 103 compensates the output power of each phase of the three-phase power grid through the AC port of the second AC-DC conversion unit 103, so that the output power of each phase of the three-phase power grid is balanced.

[0127] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present application, and all of them should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

[0128] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A power quality control system, characterized in that, The power quality control system includes: a transformer module, a first AC-DC conversion unit, a second AC-DC conversion unit, and a third AC-DC conversion unit; One end of the transformer module is used to connect to a three-phase power grid, and the other end of the transformer module is connected to the AC port of the third AC-DC conversion unit; The AC ports of the first AC-DC conversion unit and the second AC-DC conversion unit are both connected to the three-phase power grid, and the DC ports of the first AC-DC conversion unit are respectively connected to the DC ports of the second AC-DC conversion unit and the third AC-DC conversion unit to provide DC power.

2. The power quality control system according to claim 1, wherein The transformer module includes: a first transformer, a second transformer, and a third transformer; One end of the first transformer, one end of the second transformer, and one end of the third transformer are respectively connected to each phase of the three-phase power grid in one-to-one correspondence; The other end of the first transformer, the other end of the second transformer, and the other end of the third transformer are respectively connected to the AC ports of each phase of the third AC-DC conversion unit in one-to-one correspondence.

3. The power quality control system according to claim 1, characterized in that The first AC-DC conversion unit includes: a signal terminal and a DC port; The signal terminal of the first AC-DC conversion unit is connected to the signal input terminal of the third AC-DC conversion unit, and the signal terminal is used to provide a phase synchronization signal to the third AC-DC conversion unit; The DC ports of the first AC-DC conversion unit are respectively connected to the DC ports of the second AC-DC conversion unit and the third AC-DC conversion unit to provide DC power.

4. The power quality control system according to claim 2, characterized in that The power quality control system further includes: a switch module, and the AC port of the third AC-DC conversion unit includes: a first output terminal, a second output terminal, a third output terminal, and a neutral line terminal; The first output terminal, the second output terminal, and the third output terminal of the third AC-DC conversion unit are all connected to the input terminal of the switch module. The first output terminal of the third AC-DC conversion unit is connected to the other end of the first transformer, the second output terminal of the third AC-DC conversion unit is connected to the other end of the second transformer, and the third output terminal of the third AC-DC conversion unit is connected to the other end of the third transformer; The neutral line terminal of the third AC-DC conversion unit is respectively connected to the output terminal of the switch module, the other end of the first transformer, the other end of the second transformer, and the other end of the third transformer.

5. The power quality control system according to claim 4, wherein The switch module includes: a first switch unit, a second switch unit, and a third switch unit, and the third AC-DC conversion unit further includes: a signal control terminal; The input terminal of the first switch unit is connected to the first output terminal of the third AC-DC conversion unit, the output terminal of the first switch unit is connected to the neutral line terminal of the third AC-DC conversion unit, and the control terminal of the first switch unit is connected to the signal control terminal of the third AC-DC conversion unit; The input end of the second switch unit is connected to the second output end of the third AC-DC conversion unit, the output end of the second switch unit is connected to the neutral line end of the third AC-DC conversion unit, and the control end of the second switch unit is connected to the signal control end of the third AC-DC conversion unit; The input end of the third switch unit is connected to the third output end of the third AC-DC conversion unit, the output end of the third switch unit is connected to the neutral line end of the third AC-DC conversion unit, and the control end of the third switch unit is connected to the signal control end of the third AC-DC conversion unit.

6. The power quality control system according to claim 5, characterized in that The first switch unit includes: a first electronic switch; the second switch unit includes: a second electronic switch; the third switch unit includes: a third electronic switch; The input end of the first electronic switch is connected to the first output end of the third AC-DC conversion unit, the input end of the second electronic switch is connected to the second output end of the third AC-DC conversion unit, and the input end of the third electronic switch is connected to the third output end of the third AC-DC conversion unit; The output ends of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the neutral line end of the third AC-DC conversion unit, and the control ends of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the signal control end of the third AC-DC conversion unit.

7. The power quality control system according to claim 5, characterized in that The first switch unit includes: a first electronic switch and a first mechanical switch, the second switch unit includes: a second electronic switch and a second mechanical switch, and the third switch unit includes: a third electronic switch and a third mechanical switch; The input ends of the first electronic switch and the first mechanical switch are both connected to the first output end of the third AC-DC conversion unit, the input ends of the second electronic switch and the second mechanical switch are both connected to the second output end of the third AC-DC conversion unit, and the input ends of the third electronic switch and the third mechanical switch are both connected to the third output end of the third AC-DC conversion unit; The output ends of the first electronic switch, the first mechanical switch, the second electronic switch, the second mechanical switch, the third electronic switch, and the third mechanical switch are all connected to the neutral line end of the third AC-DC conversion unit; The control ends of the first electronic switch, the second electronic switch, and the third electronic switch are all connected to the signal control end of the third AC-DC conversion unit, and the control ends of the first mechanical switch, the second mechanical switch, and the third mechanical switch are all connected to an external drive circuit.

8. The power quality control system according to claim 1, characterized in that The power quality control system further includes: an energy storage module; The output end of the energy storage module is connected to the DC port of the second AC-DC conversion unit.

9. The power quality control system according to claim 1, characterized in that The power quality control system further includes: a detection and monitoring module; The detection and monitoring module is communicatively connected to the transformer module, the first AC-DC conversion unit, the second AC-DC conversion unit, and the third AC-DC conversion unit respectively.

10. The power quality control system according to claim 9, characterized in that The power quality control system further includes: at least one load; The load is connected to the three-phase power grid; The third AC-DC conversion unit is used to output a three-phase compensation voltage to the transformer module; The second AC-DC conversion unit is used to adjust the output power of the three-phase power grid.

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