A power grid voltage regulator and a power grid high and low voltage control method

Abstract

The present invention discloses a grid voltage regulator and a method for controlling high and low voltages in a grid, and relates to the field of power supply. The grid voltage regulator includes a high-frequency isolation transformer, two AC / AC modules, a first filter inductor, a second filter inductor, an AC grid equivalent power supply, a grid capacitor, and a load; wherein the first AC / AC module includes four switching tubes and the second AC / AC module includes four capacitors respectively. The primary side voltage Vp of the high-frequency isolation transformer is controlled by the first AC / AC module; the secondary side voltage Vq is obtained by induction of the secondary side of the high-frequency isolation transformer, and then the voltage Vs of the grid capacitor is controlled by the second AC / AC module; by superimposing the voltage Vs and the grid voltage Vg, the high and low voltage control of the grid voltage Vg can be achieved. The present invention adopts an AC to AC energy one-stage conversion architecture to achieve the control of voltage too low and too high problems, which greatly reduces the cost while improving work efficiency and reducing the size of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power grid voltage regulator and a method for managing high and low voltages in a power grid. Background Art

[0002] The quality of power at distribution network substations can affect the quality of power supply. Poor power quality can lead to increased line losses, equipment failures, power outages, and other issues, impacting users' lives and production. In some power supply areas, seasonal and intermittent load fluctuations can cause low transformer output voltages. These fluctuations are exacerbated by surge loads. Heavy loads at the end of the line can also lead to low voltages at the end of the line. This is particularly true in mountainous and remote areas, where some substations have long power supply radii, poor power quality at the end of the line, and low reliability. This often results in voltages that are either too high or too low compared to the standard voltage (220V). These voltages can cause users' electrical equipment to malfunction, significantly impacting regional economic and social stability.

[0003] To solve the problem of low or high power supply voltage at the distribution transformer or line end, the traditional solution is to use UPQC (Unified Power Quality Conditioner) device to deal with it. Figure 1 As shown, the UPQC device first connects a rectifier in parallel to the grid to generate DC voltage. This DC voltage is then converted into AC power through an inverter. This AC power is then fed into the grid through a coupled power-frequency transformer connected in series with the grid. This superimposes the AC voltage generated by the inverter on the load-side voltage, thereby regulating the grid voltage. When the grid voltage is too low, the UPQC can be used to increase the voltage by adding a voltage in phase with the grid voltage. When the grid voltage is too high, the UPQC can be used to reduce the voltage by adding a voltage in phase with the grid voltage, restoring the load voltage to the standard voltage (approximately 220V).

[0004] From the above analysis, it can be seen that the architecture of the UPQC device is relatively complex. It adopts a two-stage structure of rectification followed by inversion, and requires a power frequency transformer to be coupled in series with the power grid, resulting in complex control of the device, low efficiency, large size and high cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a grid voltage regulator and a method for managing high and low voltages in the grid, which can achieve the management of low and high voltage problems by adopting a one-level architecture, thereby greatly reducing costs while improving work efficiency and reducing the size of the device.

[0006] To achieve the above objectives, the present invention provides the following solutions.

[0007] In one aspect, the present invention provides a grid voltage regulator, comprising: a high-frequency isolation transformer, two AC / AC modules, a first filter inductor, a second filter inductor, an AC grid equivalent power supply, a grid capacitor, and a load; wherein the first AC / AC module comprises four switching transistors and two capacitors, namely, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, and a second capacitor; the second AC / AC module also comprises four switching transistors and two capacitors, namely, a fifth switching transistor, a sixth switching transistor, a seventh switching transistor, an eighth switching transistor, a third capacitor, and a fourth capacitor; and control terminals of all the switching transistors are connected to a modal controller.

[0008] The first end of the first switching tube is respectively connected to one end of the primary side of the high-frequency isolation transformer, the second end of the second switching tube, one end of the AC grid equivalent power supply, one end of the grid capacitor, the first end of the seventh switching tube, and the second end of the eighth switching tube; the other end of the primary side of the high-frequency isolation transformer is respectively connected to one end of the first capacitor and one end of the second capacitor; the other end of the first capacitor is respectively connected to the second end of the first switching tube and the second end of the third switching tube; the other end of the second capacitor is respectively connected to the first end of the second switching tube and the first end of the fourth switching tube; the first end of the third switching tube is respectively connected to the second end of the fourth switching tube and one end of the first filter inductor;

[0009] The first end of the fifth switching tube is respectively connected to one end of the secondary side of the high-frequency isolation transformer T, the second end of the sixth switching tube and one end of the second filter inductor; the other end of the secondary side of the high-frequency isolation transformer is respectively connected to one end of the third capacitor and one end of the fourth capacitor; the other end of the third capacitor is respectively connected to the second end of the fifth switching tube and the second end of the seventh switching tube; the other end of the fourth capacitor is respectively connected to the first end of the sixth switching tube and the first end of the eighth switching tube; the other end of the second filter inductor is respectively connected to the other end of the grid capacitor and one end of the load; the other end of the load is respectively connected to the other end of the first filter inductor and the other end of the AC grid equivalent power supply.

[0010] Optionally, the switch tube is an IGBT; the first end of the switch tube is the emitter of the IGBT; the second end of the switch tube is the collector of the IGBT; and the control end of the switch tube is the gate of the IGBT.

[0011] Optionally, the switching tube is an N-type IGBT with a damping diode; the first end of the switching tube is the emitter of the N-type IGBT; the second end of the switching tube is the collector of the N-type IGBT; the control end of the switching tube is the gate of the N-type IGBT; the positive electrode of the damping diode is connected to the emitter of the N-type IGBT; and the negative electrode of the damping diode is connected to the collector of the N-type IGBT.

[0012] Optionally, the switch tube is a MOSFET; the first end of the switch tube is the source of the MOSFET; the second end of the switch tube is the drain of the MOSFET; and the control end of the switch tube is the gate of the MOSFET.

[0013] Optionally, the switch tube is an N-channel MOSFET; the first end of the switch tube is the source of the N-channel MOSFET; the second end of the switch tube is the drain of the N-channel MOSFET; and the control end of the switch tube is the gate of the N-channel MOSFET.

[0014] Optionally, there are two H4 structures in the grid voltage regulator topology structure, wherein the first switch tube, the second switch tube, the third switch tube and the fourth switch tube constitute an H4 structure, and the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube constitute an H4 structure, and the upper and lower tubes in the H4 structure are complementary.

[0015] On the other hand, the present invention also provides a method for controlling high and low voltages in a power grid, which is used in the power grid voltage regulator. The method for controlling high and low voltages in a power grid includes:

[0016] Controlling the primary side voltage Vp of the high-frequency isolation transformer through the first AC / AC module;

[0017] The secondary side voltage Vq is obtained by induction on the secondary side of the high-frequency isolation transformer, and then the voltage Vs of the grid capacitor is controlled by the second AC / AC module;

[0018] By superimposing the voltage Vs and the grid voltage Vg, high and low voltage control of the grid voltage Vg is achieved.

[0019] Optionally, the superposition of the pass voltage Vs and the grid voltage Vg to achieve high and low voltage control of the grid voltage Vg specifically includes:

[0020] When the grid voltage Vg is too low, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs in phase with the grid voltage Vg, thereby raising the grid voltage Vg and obtaining the required AC output voltage Vo.

[0021] When the grid voltage Vg is too high, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs with a phase opposite to the grid voltage Vg, thereby reducing the grid voltage Vg and obtaining the required AC output voltage Vo.

[0022] Optionally, when the grid voltage regulator is working, the first switch tube and the second switch tube are controlled to be complementary conductive, the third switch tube and the fourth switch tube are controlled to be complementary conductive, the fifth switch tube and the sixth switch tube are controlled to be complementary conductive, and the seventh switch tube and the eighth switch tube are controlled to be complementary conductive.

[0023] Optionally, the power grid high and low voltage management method further includes:

[0024] The conduction conditions of the first to eighth switching tubes are controlled by the mode controller to realize 16 working modes.

[0025] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0026] Traditional UPQC devices for voltage management use a two-stage structure with rectification followed by inversion, and require a power-frequency transformer to be coupled in series with the power grid, resulting in complex control, low efficiency, large size, and high cost. Compared with traditional UPQC devices, the grid voltage regulator for voltage management proposed in the present invention adopts a first-level architecture with a high-frequency isolated AC / AC topology. To address undervoltage and overvoltage issues, only one-level AC-to-AC energy conversion is required, eliminating the need for a power-frequency transformer, rectifier, and inverter. This eliminates noise pollution while reducing the number of components, significantly reducing costs while improving work efficiency and reducing device size. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 It is a schematic diagram of the general structure of the UPQC device;

[0029] Figure 2 This is a schematic diagram of the high-frequency isolated converter architecture;

[0030] Figure 3 This is a schematic diagram of a typical specific architecture of a high-frequency isolated converter;

[0031] Figure 4 A schematic diagram of the topological structure of the grid voltage regulator provided by the present invention;

[0032] Figure 5 This is the principle diagram of working mode 0000;

[0033] Figure 6 This is the principle diagram of working mode 0001;

[0034] Figure 7 This is a schematic diagram of the working mode 0010;

[0035] Figure 8 This is a schematic diagram of the working mode 0011;

[0036] Figure 9 This is the principle diagram of working mode 0100;

[0037] Figure 10 This is a schematic diagram of the working mode 0101;

[0038] Figure 11 This is a schematic diagram of the working mode 0110;

[0039] Figure 12 This is a schematic diagram of the working mode 0111;

[0040] Figure 13 Schematic diagram of the working mode 1000;

[0041] Figure 14 Schematic diagram of the working mode 1001;

[0042] Figure 15 Schematic diagram of the working mode 1010;

[0043] Figure 16 Schematic diagram of the working mode 1011;

[0044] Figure 17 Schematic diagram of the working mode 1100;

[0045] Figure 18 Schematic diagram of the working mode 1101;

[0046] Figure 19 Schematic diagram of the working mode 1110;

[0047] Figure 20 Schematic diagram of the working mode 1111;

[0048] Figure 21 Schematic diagram of the three-phase architecture of the grid voltage regulator of the present invention. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] The purpose of the present invention is to provide a grid voltage regulator and a method for managing high and low voltages in the grid, which can achieve the management of low and high voltage problems by adopting a one-level architecture, thereby greatly reducing costs while improving work efficiency and reducing the size of the device.

[0051] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] High frequency isolated converter architecture such as Figure 2 As shown, when the AC grid voltage Vg is high or low, the output voltage Vo can be stabilized by the isolation converter.

[0053] A typical specific architecture in the high-frequency isolated converter architecture is as follows Figure 3 As shown in the figure, T represents the high-frequency isolation transformer, Cs represents the capacitor, Vs represents the capacitor voltage, Vg represents the grid voltage, and Vo represents the output voltage. If the AC grid voltage Vg experiences high or low voltage, the output voltage Vo can be stabilized by following the steps of AC / AC module → high-frequency isolation transformer → AC / AC module.

[0054] Based on this, the present invention provides a grid voltage regulator, whose topology is as follows Figure 4 As shown in FIG, by accurately controlling two sets of full-bridge converters, the existing high-frequency isolated converter can be replaced to achieve stable output voltage Vo under high-frequency isolation. Figure 4 The present invention provides a grid voltage regulator comprising: a high-frequency isolation transformer T, two AC / AC modules, a first filter inductor L1, a second filter inductor L2, an AC grid equivalent power supply, a grid capacitor Cs, and a load R. The first AC / AC module comprises a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a first capacitor C1, and a second capacitor C2. The second AC / AC module comprises a fifth switching transistor T5, a sixth switching transistor T6, a seventh switching transistor T7, an eighth switching transistor T8, a third capacitor C3, and a fourth capacitor C4.

[0055] Specifically, the first end of the first switch tube T1 is respectively connected to one end of the primary side of the high-frequency isolation transformer T, the second end of the second switch tube T2, one end of the AC grid equivalent power supply, one end of the grid capacitor Cs, the first end of the seventh switch tube T7, and the second end of the eighth switch tube T8; the other end of the primary side of the high-frequency isolation transformer T is respectively connected to one end of the first capacitor C1 and one end of the second capacitor C2; the other end of the first capacitor C1 is respectively connected to the second end of the first switch tube T1 and the second end of the third switch tube T3; the other end of the second capacitor C2 is respectively connected to the first end of the second switch tube T2 and the first end of the fourth switch tube T4; the first end of the third switch tube T3 is respectively connected to the second end of the fourth switch tube T4 and one end of the first filter inductor L1.

[0056] The first end of the fifth switch tube T5 is respectively connected to one end of the secondary side of the high-frequency isolation transformer T, the second end of the sixth switch tube T6 and one end of the second filter inductor L2; the other end of the secondary side of the high-frequency isolation transformer T is respectively connected to one end of the third capacitor C3 and one end of the fourth capacitor C4; the other end of the third capacitor C3 is respectively connected to the second end of the fifth switch tube T5 and the second end of the seventh switch tube T7; the other end of the fourth capacitor C4 is respectively connected to the first end of the sixth switch tube T6 and the first end of the eighth switch tube T8; the other end of the second filter inductor L2 is respectively connected to the other end of the grid capacitor Cs and one end of the load R; the other end of the load R is respectively connected to the other end of the first filter inductor L1 and the other end of the AC grid equivalent power supply.

[0057] In one embodiment, the switch tubes T1 to T8 may be IGBT elements. In this embodiment, the first end of the switch tube is the emitter of the IGBT; the second end of the switch tube is the collector of the IGBT; and the control end of the switch tube is the gate of the IGBT.

[0058] exist Figure 4 In another embodiment shown, the switching tubes T1 to T8 can adopt N-type IGBTs with damping diodes. In this embodiment, the first end of the switching tube is the emitter of the N-type IGBT; the second end of the switching tube is the collector of the N-type IGBT; the control end of the switching tube is the gate of the N-type IGBT; the positive electrode of the damping diode is connected to the emitter of the N-type IGBT; and the negative electrode of the damping diode is connected to the collector of the N-type IGBT.

[0059] In another embodiment, the switch tubes T1 to T8 may also be MOSFETs; in this embodiment, the first end of the switch tube is the source of the MOSFET; the second end of the switch tube is the drain of the MOSFET; and the control end of the switch tube is the gate of the MOSFET.

[0060] In another embodiment, the switch tubes T1 to T8 may also be N-channel MOSFETs; in this embodiment, the first end of the switch tube is the source of the N-channel MOSFET; the second end of the switch tube is the drain of the N-channel MOSFET; and the control end of the switch tube is the gate of the N-channel MOSFET.

[0061] The primary voltage Vp of the high-frequency isolation transformer T is controlled by switches T1, T2, T3, and T4, and capacitors C1 and C2. The secondary voltage Vq is sensed by the high-frequency isolation transformer. Furthermore, the voltage Vs of the grid capacitor Cs is controlled by switches T5, T6, T7, and T8, and capacitors C3 and C4. By superimposing voltage Vs on the grid voltage Vg, high and low voltages of the grid voltage Vg can be controlled.

[0062] Specifically, when the voltage Vg is too low, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs in phase with the grid voltage Vg, thereby raising the grid voltage Vg and obtaining the required AC output voltage Vo (typically 220V). Given that the current voltage range for grid high and low voltage regulation is -10% to +7%, or 198V to 235.4V, the grid voltage regulator of the present invention can output voltages wider than this range, not limited to the conventional 220V.

[0063] When the Vg voltage is too high, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs with a phase opposite to the grid voltage Vg, thereby reducing the grid voltage Vg and obtaining the required AC output voltage Vo (usually 220V).

[0064] like Figure 4 As shown, there are two H4 structures in the topology of the grid voltage regulator of the present invention, wherein the first switch tube T1, the second switch tube T2, the third switch tube T3 and the fourth switch tube T4 constitute an H4 structure, the fifth switch tube T5, the sixth switch tube T6, the seventh switch tube T7 and the eighth switch tube T8 constitute an H4 structure, and the upper and lower tubes in each H4 structure are complementary conductive. Therefore, during normal operation, the switch tubes T1 and T2 are complementary conductive, the switch tubes T3 and T4 are complementary conductive, the switch tubes T5 and T6 are complementary conductive, and the switch tubes T7 and T8 are complementary conductive. The control ends of all the switch tubes T1 to T8 are connected to the mode controller. According to the conduction conditions of the switch tubes T1 to T8 controlled by the mode controller, there are theoretically 16 working modes, which are respectively as follows: Figures 5 to 20The specific topological modal analysis is as follows.

[0065] Figure 5 In the mode 0000 shown, the switches T2, T4, T6, and T8 are closed, the primary side voltage Vp of the high-frequency isolation transformer T is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the high-frequency isolation transformer T is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp is charged, and the secondary side inductor Lq is discharged.

[0066] Figure 6 In the mode 0001 shown, the switches T2, T4, T6, and T7 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp is energized, and the secondary side inductor Lq is energized.

[0067] Figure 7 In the mode 0010 shown, the switches T2, T4, T5, and T8 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp is energized, and the secondary side inductor Lq is energized.

[0068] Figure 8 In the mode 0011 shown, the switches T2, T4, T5, and T7 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp is charged, and the secondary side inductor Lq is discharged.

[0069] Figure 9 In the mode 0100 shown, the switches T2, T3, T6, and T8 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp discharges energy, and the secondary side inductor Lq discharges energy.

[0070] Figure 10 In the mode 0101 shown, the switches T2, T3, T6, and T7 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp discharges energy, and the secondary side inductor Lq charges energy.

[0071] Figure 11 In the mode 0110 shown, the switches T2, T3, T5, and T8 are closed, the primary side voltage Vp of the transformer is the negative value of the voltage of the second capacitor C2, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp discharges energy, and the secondary side inductor Lq charges energy.

[0072] Figure 12In the illustrated mode 0111, switches T2, T3, T5, and T7 are closed, the transformer primary voltage is the negative value of the second capacitor C2 voltage, the transformer secondary voltage is the positive value of the third capacitor C3 voltage, the primary inductor Lp discharges energy, and the secondary inductor Lq discharges energy.

[0073] Figure 13 In the mode 1000 shown, the switches T1, T4, T6, and T8 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp releases energy, and the secondary side inductor Lq releases energy.

[0074] Figure 14 In the mode 1001 shown, the switches T1, T4, T6, and T7 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp discharges energy, and the secondary side inductor Lq charges energy.

[0075] Figure 15 In the mode 1010 shown, the switches T1, T4, T5, and T8 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp discharges energy, and the secondary side inductor Lq charges energy.

[0076] Figure 16 In the mode 1011 shown, the switches T1, T4, T5, and T7 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp discharges energy, and the secondary side inductor Lq discharges energy.

[0077] Figure 17 In the mode 1100 shown, the switches T1, T3, T6, and T8 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp is charged, and the secondary side inductor Lq is discharged.

[0078] Figure 18 In the mode 1101 shown, the switches T1, T3, T6, and T7 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the negative value of the voltage of the fourth capacitor C4, the primary side inductor Lp is energized, and the secondary side inductor Lq is energized.

[0079] Figure 19In the mode 1110 shown, the switches T1, T3, T5, and T8 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp discharges energy, and the secondary side inductor Lq charges energy.

[0080] Figure 20 In the mode 1111 shown, the switches T1, T3, T5, and T7 are closed, the primary side voltage Vp of the transformer is the positive value of the voltage of the first capacitor C1, the secondary side voltage Vq of the transformer is the positive value of the voltage of the third capacitor C3, the primary side inductor Lp is charged, and the secondary side inductor Lq is discharged.

[0081] Figure 4 The topology shown in the figure theoretically has 16 operating modes, and its theoretical control methods are diverse. Here we only give a simple control method to illustrate. Taking the positive half cycle of the sinusoidal voltage of the grid as an example, in Figure 4 The middle is positive at the top and negative at the bottom, as briefly explained below.

[0082] During the positive half-cycle of the grid, switches T4 and T8 are always on. Conversely, during the negative half-cycle, switches T3 and T7 are always on. This description only applies to the positive half-cycle; the negative half-cycle is similar. During the positive half-cycle of the grid, the regulator operates in the following four modes, continuously switching at high frequency.

[0083] Mode 1010: The mode controller controls the switches T1, T4, T5, and T8 to be closed. On the primary side of the transformer, the grid is connected to the capacitors C1 and C2 through the first filter inductor L1. After the voltage Vq is induced on the secondary side of the transformer, it is supplied to the capacitors C3 and C4, and the load R is powered through the second filter inductor L2.

[0084] Mode 1000: The mode controller controls the switching tubes T1, T4, T6, and T8 to be closed. On the primary side of the transformer, the grid is connected to the capacitors C1 and C2 through the first filter inductor L1. After the voltage Vq is induced on the secondary side of the transformer, it is supplied to the fourth capacitor C4 and the load R is powered through the second filter inductor L2.

[0085] Mode 0010: The mode controller controls the switches T2, T4, T5, and T8 to be closed. On the primary side of the transformer, the grid is connected to the second capacitor C2 through the first filter inductor L1. After the voltage Vq is induced on the secondary side of the transformer, it is supplied to the capacitors C3 and C4, and the load R is powered through the second filter inductor L2.

[0086] Mode 0000: The mode controller controls the switches T2, T4, T6, and T8 to be closed. On the primary side of the transformer, the grid is connected to the second capacitor C2 through the first filter inductor L1. After the voltage Vq is induced on the secondary side of the transformer, it is supplied to the fourth capacitor C4 and the load R is powered through the second filter inductor L2.

[0087] The grid voltage regulator of the present invention utilizes a high-frequency isolated AC / AC topology to achieve a single-stage AC-to-AC energy conversion, effectively addressing both undervoltage and overvoltage issues. Conventional UPQC devices employ a two-stage structure with rectification followed by inversion, and require a power-frequency transformer to be coupled in series with the grid, resulting in complex control, low efficiency, large size, and high cost. The present invention, however, utilizes only a single-stage conversion and eliminates the need for a power-frequency transformer, effectively increasing the overall power density of the device while eliminating power-frequency transformer losses and noise pollution.

[0088] See also Figures 2 to 20 The above description is all about the application of the grid voltage regulator of the present invention in a single-phase system. Furthermore, the grid voltage regulator architecture of the present invention can also be applied to a three-phase system. Its working principle is similar to that of the single-phase system. The specific architecture is as follows: Figure 21 As shown, the grid voltage regulator architecture of the present invention is applied to each phase.

[0089] When the grid voltage regulator provided by the present invention is applied to a three-phase system, each phase controls the primary side voltage Vp of the high-frequency isolation transformer T through a first AC / AC module. The secondary side voltage Vq is sensed by the high-frequency isolation transformer T, and then the voltage Vs of the grid capacitor Cs is controlled through a second AC / AC module. By superimposing the voltage Vs and the grid voltage Vg, high and low voltage control of each phase grid voltage Vg is achieved.

[0090] Specifically, when the grid voltage Vg is too low, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs in phase with the grid voltage Vg, thereby increasing the grid voltage Vg and obtaining the desired AC output voltage Vo. When the grid voltage Vg is too high, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs in phase with the grid voltage Vg, thereby reducing the grid voltage Vg and obtaining the desired AC output voltage Vo. The AC output voltage Vo is typically 220V.

[0091] When each phase of the grid voltage regulator is working, the first switch tube T1 and the second switch tube T2 are controlled to be complementary to each other, the third switch tube T3 and the fourth switch tube T4 are controlled to be complementary to each other, the fifth switch tube T5 and the sixth switch tube T6 are controlled to be complementary to each other, and the seventh switch tube T7 and the eighth switch tube T8 are controlled to be complementary to each other. By controlling the conduction of the switches T1 to T8, 16 working modes are realized. The principle is the same as Figures 5 to 20 The 16 operating modes shown are similar and will not be described again here.

[0092] The present invention proposes a new circuit topology for addressing the problems of undervoltage and overvoltage in power supply. Compared with the traditional UPQC device, the grid voltage regulator of the present invention adopts a high-frequency isolated AC / AC topology. While addressing the problems of undervoltage and overvoltage, it achieves one-stage energy conversion without noise pollution, while greatly reducing the volume, improving efficiency, and increasing power density.

[0093] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A grid voltage regulator, characterized in that: include: A high-frequency isolation transformer, two AC / AC modules, a first filter inductor, a second filter inductor, an AC grid equivalent power supply, a grid capacitor, and a load; wherein the first AC / AC module includes four switching transistors and two capacitors, namely, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a first capacitor, and a second capacitor; the second AC / AC module also includes four switching transistors and two capacitors, namely, a fifth switching transistor, a sixth switching transistor, a seventh switching transistor, an eighth switching transistor, a third capacitor, and a fourth capacitor; the control terminals of all the switching transistors are connected to the modal controller; The first end of the first switching tube is respectively connected to one end of the primary side of the high-frequency isolation transformer, the second end of the second switching tube, one end of the AC grid equivalent power supply, one end of the grid capacitor, the first end of the seventh switching tube, and the second end of the eighth switching tube; the other end of the primary side of the high-frequency isolation transformer is respectively connected to one end of the first capacitor and one end of the second capacitor; the other end of the first capacitor is respectively connected to the second end of the first switching tube and the second end of the third switching tube; the other end of the second capacitor is respectively connected to the first end of the second switching tube and the first end of the fourth switching tube; the first end of the third switching tube is respectively connected to the second end of the fourth switching tube and one end of the first filter inductor; The first end of the fifth switching tube is respectively connected to one end of the secondary side of the high-frequency isolation transformer T, the second end of the sixth switching tube and one end of the second filter inductor; the other end of the secondary side of the high-frequency isolation transformer is respectively connected to one end of the third capacitor and one end of the fourth capacitor; the other end of the third capacitor is respectively connected to the second end of the fifth switching tube and the second end of the seventh switching tube; the other end of the fourth capacitor is respectively connected to the first end of the sixth switching tube and the first end of the eighth switching tube; the other end of the second filter inductor is respectively connected to the other end of the grid capacitor and one end of the load; the other end of the load is respectively connected to the other end of the first filter inductor and the other end of the AC grid equivalent power supply.

2. The grid voltage regulator according to claim 1, characterized in that The switch tube is an IGBT; the first end of the switch tube is the emitter of the IGBT; the second end of the switch tube is the collector of the IGBT; and the control end of the switch tube is the gate of the IGBT.

3. The grid voltage regulator according to claim 1, characterized in that The switching tube is an N-type IGBT with a damping diode; the first end of the switching tube is the emitter of the N-type IGBT; the second end of the switching tube is the collector of the N-type IGBT; the control end of the switching tube is the gate of the N-type IGBT; the anode of the damping diode is connected to the emitter of the N-type IGBT; and the cathode of the damping diode is connected to the collector of the N-type IGBT.

4. The grid voltage regulator according to claim 1, characterized in that The switch tube is a MOSFET; the first end of the switch tube is the source of the MOSFET; the second end of the switch tube is the drain of the MOSFET; and the control end of the switch tube is the gate of the MOSFET.

5. The grid voltage regulator according to claim 1, characterized in that The switch tube is an N-channel MOSFET; the first end of the switch tube is the source of the N-channel MOSFET; the second end of the switch tube is the drain of the N-channel MOSFET; and the control end of the switch tube is the gate of the N-channel MOSFET.

6. The grid voltage regulator according to claim 1, characterized in that There are two H4 structures in the grid voltage regulator topology structure, wherein the first switch tube, the second switch tube, the third switch tube and the fourth switch tube constitute an H4 structure, and the fifth switch tube, the sixth switch tube, the seventh switch tube and the eighth switch tube constitute an H4 structure, and the upper and lower tubes in the H4 structure are complementary.

7. A method for controlling high and low voltage in a power grid, characterized in that: A grid voltage regulator for use in any one of claims 1 to 6, wherein the grid high and low voltage management method comprises: Controlling the primary side voltage Vp of the high-frequency isolation transformer through the first AC / AC module; The secondary side voltage Vq is obtained by induction on the secondary side of the high-frequency isolation transformer, and then the voltage Vs of the grid capacitor is controlled by the second AC / AC module; By superimposing the voltage Vs and the grid voltage Vg, high and low voltage control of the grid voltage Vg is achieved.

8. The method for controlling high and low voltages in a power grid according to claim 7, characterized in that: The superposition of the voltage Vs and the grid voltage Vg is used to achieve high and low voltage control of the grid voltage Vg, specifically including: When the grid voltage Vg is too low, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs in phase with the grid voltage Vg, thereby raising the grid voltage Vg and obtaining the required AC output voltage Vo. When the grid voltage Vg is too high, the grid voltage regulator causes the grid capacitor Cs to generate a voltage Vs with a phase opposite to the grid voltage Vg, thereby reducing the grid voltage Vg and obtaining the required AC output voltage Vo.

9. The method for controlling high and low voltages in a power grid according to claim 8, characterized in that: When the grid voltage regulator is working, the first switch tube and the second switch tube are controlled to be complementary turned on, the third switch tube and the fourth switch tube are controlled to be complementary turned on, the fifth switch tube and the sixth switch tube are controlled to be complementary turned on, and the seventh switch tube and the eighth switch tube are controlled to be complementary turned on.

10. The method for controlling high and low voltages in a power grid according to claim 9, characterized in that: Also includes: The conduction conditions of the first to eighth switching tubes are controlled by the mode controller to realize 16 working modes.

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