High-voltage ac line voltage stabilization system

Abstract

The present application relates to a kind of voltage stabilizing device for power line voltage.Many power line voltage is lower than the allowable range, while voltage fluctuation is large, power grid frequently appears overload phenomenon, leading to line loss significantly increases, power qualified rate is low, and cause great harm to electrical equipment, even cause many electrical equipment cannot be used.The high-voltage AC line voltage stabilizing system of the present application is suitable for high line voltage, can effectively stabilize power supply voltage of power grid, has fast response speed, low cost, high reliability, easy maintenance, and can effectively improve the actual power transmission capacity of distribution network.

Description

Technical Field

[0001] The embodiments disclosed in this invention relate to the field of circuit technology, and more specifically, to a voltage regulator circuit system for stabilizing the mains power supply voltage. Background Technology

[0002] With the improvement of people's living standards and the widespread use of household appliances, especially residential users' electricity consumption has increased significantly year by year. However, the upgrading and renovation of power distribution lines in factories, mines, residential areas, and shops has lagged behind, resulting in voltage at the end of the lines being far below the allowable range. At the same time, voltage fluctuations are large, and the power grid frequently experiences overload. Non-lighting loads such as washing machines, air conditioners, and televisions cannot work properly and cause great damage to electrical equipment. Meanwhile, because the newly added electrical loads use a large number of rotating equipment such as motors and compressors and power electronic devices, the demand for reactive power is large, and a large number of high-order harmonic currents are generated. This leads to a significant increase in low-voltage line losses, a low power factor in the entire power grid, and large fluctuations in supply voltage.

[0003] The best solution to the aforementioned problems of low voltage and large voltage fluctuations is to directly install power supply voltage stabilization devices on the distribution network. Installing automatic voltage regulators on the power grid lines can automatically adjust the power supply voltage in real time, stabilizing it at the standard value. This allows for the direct supply of reactive power to electrical equipment, increasing the actual transmission capacity of the distribution network; improving the operational safety of power supply transformers; and significantly mitigating abnormal conditions such as voltage flicker caused by high-voltage line lightning strikes, momentary short circuits, and overloads, thus protecting the safety of electrical equipment.

[0004] Chinese patent CN204360256U discloses a contactless AC voltage regulator that uses a multi-winding transformer and multiple thyristor switching to achieve voltage regulation. This technology is a stepped voltage regulation method, but to prevent excessively large step differences, it requires numerous thyristor switching switches, resulting in complex circuitry and high cost. Furthermore, due to the slow switching speed of the thyristors (the fastest being only 10ms), it is ineffective against rapid voltage fluctuations in the power grid. In particular, when the output voltage is regulated to a high level, if the grid voltage experiences a rapid jump, the output voltage may overvoltage due to the slow response time, endangering the safety of electrical equipment.

[0005] Due to limitations in the voltage rating and cost of power semiconductor devices, there is currently no cost-effective technical solution for voltage stabilization systems on high-voltage lines. Conventional on-load tap-changing transformers cannot continuously adjust voltage and have a slow response speed, making them unable to cope with rapid fluctuations in line voltage. Summary of the Invention

[0006] The purpose of this invention is to design a high-voltage AC line voltage stabilization system that uses low-voltage power semiconductor technology to effectively regulate the voltage of a high-voltage power grid. It has the advantages of fast response speed, low cost, high reliability and convenient maintenance.

[0007] The high-voltage AC line stabilization system designed in this invention includes a single-phase or multi-phase transformer, the primary winding of which is connected to an AC power input, and each secondary winding of which includes two leads. It also includes one or more converter modules, each containing two input ports and one output port. The two input ports of the converter module are respectively connected to the leads of the secondary winding of the transformer, and the output port of the converter module serves as the output of this invention. The converter module enables real-time voltage regulation, stabilizes the output voltage, and provides dynamic reactive power compensation. Furthermore, it includes one or more commutation modules, each containing one input port and one or two output ports. The input port of the commutation module is connected to the primary winding of the transformer, and one or two output ports are connected to the secondary winding of the transformer. The commutation module can switch the polarity of the transformer windings to increase or decrease the output voltage.

[0008] In some embodiments disclosed in this invention, one or more bypass modules are also included. The bypass module includes an input port and an output port. The input port of the bypass module is connected to the primary winding of the transformer, and the output port of the bypass module is connected to the output port of the converter module. When the commutation module, converter module or transformer fails or malfunctions, the bypass module can cut off the fault and directly connect the input voltage to the output terminal.

[0009] In some embodiments disclosed in this invention, the primary winding of the transformer is star-connected.

[0010] In some embodiments disclosed in this invention, the converter module includes a two-phase inverter bridge circuit, which is composed of a two-level inverter circuit or a midpoint clamped three-level inverter circuit. The midpoint of one arm of the two-phase inverter bridge circuit serves as one input port of the converter module. It also includes two sets of capacitors connected in series, one end of which is connected to the positive terminal of the two-phase inverter bridge circuit, and the other end is connected to the negative terminal of the two-phase inverter bridge circuit. The midpoint of the two sets of capacitors connected in series serves as the other input port of the converter module. Furthermore, it includes a filter, one end of which is connected to the midpoint of one arm of the two-phase inverter bridge circuit, and the other end of which serves as the output port of the converter module. The filter is used to filter out the output current and voltage harmonics of the converter module.

[0011] In some embodiments disclosed in this invention, the commutation module includes two switches connected in series, with the midpoint serving as the input port of the commutation module and the other two ends serving as the two output ports of the commutation module; the switches are composed of mechanical switches or bidirectional thyristors, and the bidirectional thyristors are composed of two thyristors connected in parallel with opposite directions; the switches can also be composed of mechanical switches and bidirectional thyristors connected in parallel to form a composite switch; the switches can also be composed of two IGBTs connected in reverse series; by switching the two switches, the polarity of the transformer secondary winding connection can be changed, thereby increasing or decreasing the system output voltage.

[0012] In some embodiments disclosed in this invention, the commutation module includes a jumper wire, one end of which serves as an input port of the commutation module and the other end of which serves as an output port of the commutation module. In applications where voltage boosting or deboosting does not require switching windings, the jumper wire is used to reduce system cost.

[0013] In some embodiments disclosed in this invention, the bypass module consists of a switch, which is a mechanical switch or a bidirectional thyristor, and the bidirectional thyristor is composed of two thyristors connected in parallel with opposite directions; the switch may also be composed of a mechanical switch and a bidirectional thyristor connected in parallel to form a composite switch. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments disclosed in this invention, the accompanying drawings of the embodiments will be briefly described below. It should be understood that the drawings described below only relate to some embodiments disclosed in this invention, and are not intended to limit the scope of this invention.

[0015] Figure 1 This is an electrical structure diagram of a high-voltage AC line voltage stabilization system according to an embodiment of the present invention.

[0016] Figure 2 This is an exemplary circuit diagram of a converter module according to an embodiment of the present invention.

[0017] Figure 3 This is an exemplary circuit diagram of a bypass module according to an embodiment disclosed in this invention.

[0018] Figure 4 This is an exemplary circuit diagram of a commutation module according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments disclosed in this invention clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the described embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this invention.

[0020] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms such as those defined in commonly used dictionaries shall be interpreted as having the meaning consistent with their meaning in the context of the specification and in the relevant art, and shall not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein. As used herein, the statement of “connecting” or “coupling” two or more parts together shall mean that these parts are directly joined together or joined through one or more intermediate components.

[0021] Figure 1 This is an electrical structure diagram of a three-phase high-voltage AC line voltage stabilization system according to an embodiment of the present invention. The three-phase power inputs (A1, B1, C1) are coupled to the primary winding of a three-phase transformer (1). The two leads of each secondary winding of the transformer (1) are respectively coupled to the two input ports of converter modules (3) M1, M2, and M3. The output ports of the converter modules (3) serve as the output terminals (A3, B3, C3) of the present invention. The converter modules (3) realize real-time voltage regulation, stabilize the output voltage, and also have dynamic reactive power compensation functions.

[0022] Figure 1 The input ports of the three commutation modules (4) TSL1, TSL2 and TSL3 are respectively coupled to the three-phase power input terminal, while the two output ports of each commutation module (4) are respectively coupled to the secondary winding of the transformer (1). The commutation module (4) can switch the polarity of the transformer winding, thereby increasing or decreasing the output voltage.

[0023] Figure 1 The three input terminals of the bypass module (2) MP1, MP2, and MP3 are respectively coupled to the three-phase power input, and the output terminal of the bypass module (2) is respectively coupled to the output port of the converter module (3). The bypass module (2) is used to realize the fault or maintenance protection function. That is, when the commutation module (4), converter module (3) or transformer (1) fails or is abnormal, the bypass module (2) is closed, and the three-phase power input is directly connected to the output terminal to cut off the fault.

[0024] Figure 2This is an exemplary circuit diagram of a converter module according to an embodiment of the present invention. For simplicity, Figure 2 The example diagram of the medium converter module uses a two-phase, two-level inverter bridge circuit, while the converter module can also be composed of a midpoint clamped three-level inverter circuit or an inverter circuit with other topologies. Figure 2 The circuit includes two parallel bridge arms (5) and two sets of series-connected capacitor banks (6) connected in parallel at both ends of the bridge arms (5). The midpoint of one bridge arm of the two-phase inverter bridge circuit serves as one input port of the converter module, the midpoint of the other bridge arm is connected to an inductor, the other end of the inductor serves as the output port of the converter module, and the midpoint of the capacitor serves as the other input port of the converter module.

[0025] Figure 2 The inductor in the filter performs the function of filtering out the output current and voltage harmonics of the converter module. There are various circuit implementations for filters, including LC circuits, LCL circuits, etc., which are well known to those skilled in the art and are all within the scope of protection disclosed in this invention.

[0026] Figure 3 This is an exemplary circuit diagram of a bypass module according to an embodiment of the present invention. The bypass module includes a set of thyristors connected in parallel with opposite directions. The thyristors connected in parallel with opposite directions form a bidirectional switch. When a trigger current is applied to the gate of the thyristor, the thyristor is turned on, and when no trigger current is applied to its gate, the thyristor is turned off. Therefore, the circuit can be turned on and off.

[0027] The bypass module can also be composed of a mechanical switch, which can also realize the function of turning the circuit on and off. The bypass function can also be realized by connecting the mechanical switch and the thyristor switch in parallel.

[0028] Figure 4 This is an exemplary circuit diagram of a commutation module according to an embodiment disclosed in this invention. Figure 4 It contains two sets of thyristors connected in series and in parallel with opposite directions. The midpoint serves as the input port of the commutation module, while the other two ends serve as the two output ports of the commutation module. Figure 4 The thyristors connected in parallel with opposing sides can be constructed using a mechanical switch or two IGBTs connected in reverse series. The switch can also be constructed by connecting a mechanical switch and a bidirectional thyristor in parallel to form a composite switch. By controlling the switching state of the two switches, the input terminal of the commutation module can be connected to one of the two output terminals. Simultaneously, through control, it is ensured that only one of the two switches is in the on state at any given time.

[0029] The commutation module can also be implemented by a jumper wire. One end of the jumper wire serves as the input port of the commutation module, and the other end serves as one of the two output ports of the commutation module according to the output voltage requirements. This scheme essentially replaces the function of the commutation module with a wire. For applications where voltage boosting or deboosting does not require switching windings, this embodiment can reduce system costs.

[0030] In summary, the high-voltage AC line voltage stabilization system disclosed in this invention can efficiently and economically regulate the line voltage and stabilize the output voltage. Due to the adoption of power electronic inverter technology, it has the characteristics of fast response speed, high reliability, and convenient maintenance.

[0031] Unless otherwise expressly indicated by the context, the singular form of words used herein and in the appended claims includes the plural form, and vice versa. Thus, when referring to the singular, the plural form of the corresponding term is generally included. Similarly, the terms “comprising” and “including” shall be interpreted as including rather than exclusively. Likewise, the terms “including” and “or” shall be interpreted as including unless such interpretation is expressly prohibited herein. Where the term “example” is used herein, particularly when it follows a set of terms, the “example” is merely exemplary and illustrative and should not be considered exclusive or extensive.

[0032] Further aspects and scope of adaptation become apparent from the description provided herein. It should be understood that various aspects of this application may be implemented individually or in combination with one or more other aspects. It should also be understood that the descriptions and specific embodiments herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0033] Several embodiments of this disclosure have been described in detail above. However, it is obvious that those skilled in the art can make various modifications and variations to the embodiments of this disclosure without departing from the spirit and scope of this disclosure. The scope of protection of this disclosure is defined by the appended claims.

Claims

1. A high-voltage AC line voltage stabilization system, characterized in that, It includes: A multiphase transformer, wherein the primary winding of the transformer is connected to an AC power input, and each secondary winding of the transformer includes two leads; Multiple converter modules are provided, with the number of converter modules being the same as the number of phases of the transformer. Each converter module includes two input ports and one output port. The two input ports of each converter module are respectively connected to the two leads of the secondary winding of the transformer. The output port of each converter module serves as the output terminal of the high-voltage AC line voltage stabilization system. The converter modules realize real-time voltage regulation to stabilize the output voltage and also have the function of dynamic reactive power compensation. Multiple commutation modules, the same number as the converter modules, each commutation module includes one input port and two output ports. The input port of each commutation module is connected to the AC power input, and the two output ports of each commutation module are connected to the two leads of the secondary winding of the transformer. Each commutation module includes two switches connected in series, with the midpoint serving as the input port of the commutation module and the other two ends serving as the two output ports of the commutation module. The switch is composed of a mechanical switch or a bidirectional thyristor, wherein the bidirectional thyristor is composed of two thyristors connected in parallel with opposite directions; or, the switch is composed of a mechanical switch and a bidirectional thyristor connected in parallel to form a composite switch; or, the switch is composed of two IGBTs connected in reverse series; by switching the two switches, the polarity of the transformer secondary winding connection is changed, thereby increasing or decreasing the system output voltage.

2. The high-voltage AC line voltage stabilization system according to claim 1, characterized in that, It also includes a bypass module, the same number of which are the same as the converter module. The bypass module includes an input port and an output port. The input port of the bypass module is connected to the primary winding of the transformer, and the output port of the bypass module is connected to the output port of the converter module. When the commutation module, converter module, or transformer malfunctions or becomes abnormal, the bypass module is used to cut off the fault and directly connect the input voltage to the output terminal.

3. The high-voltage AC line stabilization system according to claim 1, characterized in that, The primary winding of the transformer is connected in a star configuration.

4. The high-voltage AC line voltage stabilization system according to claim 1, characterized in that, The converter module also includes: A two-phase inverter bridge circuit is composed of a two-level inverter circuit or a midpoint clamped three-level inverter circuit, wherein the midpoint of one of the bridge arms of the two-phase inverter bridge circuit serves as an input port of the converter module. Two sets of capacitors are connected in series, one end of which is connected to the positive terminal of the two-phase inverter bridge circuit, and the other end is connected to the negative terminal of the two-phase inverter bridge circuit. The midpoint of the two sets of capacitors connected in series serves as another input port of the converter module. A filter is provided, with one end connected to the midpoint of the other arm of the two-phase inverter bridge circuit, and the other end of the filter serving as the output port of the converter module. The filter is used to filter out the output current and voltage harmonics of the converter module.

5. The high-voltage AC line voltage stabilization system according to claim 2, characterized in that, The bypass module consists of a switch, which is either a mechanical switch or a bidirectional thyristor. The bidirectional thyristor is composed of two thyristors connected in parallel with opposite directions; or, it is composed of a mechanical switch and a bidirectional thyristor connected in parallel to form a composite switch.

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