Power grid alternating current compensation and power factor improvement system based on super capacitor

Abstract

The utility model discloses a power grid alternating current compensation and power factor boosting system based on a super capacitor, which comprises a three-phase circuit and a system detection control unit, and further comprises a power factor boosting unit and an alternating current compensation unit which are arranged on the three-phase circuit, wherein the power factor boosting unit comprises a transduction inductor and a three-phase PFC (Power Factor Correction) module; the AC compensation unit comprises a three-phase inversion module electrically connected with the output end of the transduction inductor, a buck-boost bidirectional conversion module electrically connected with the output end of the three-phase inversion module, an energy storage inductor electrically connected with the output end of the buck-boost bidirectional conversion module, and a super capacitor module electrically connected with the output end of the energy storage inductor. According to the utility model, the power factor of the power utilization terminal is improved through the mutual cooperation of the power factor improving unit and the alternating current compensation unit, transient emergency alternating current power supply is provided when a power grid is powered off, part of electric equipment with relatively important requirements is protected, and the power utilization cost is saved for users of the power utilization terminal.

Description

Technical Field

[0001] The utility model relates to the field of electric power, and more specifically, to a frequency converter power supply compensation and endurance system based on super capacitors. Background Technique

[0002] With the increasingly serious shortage of global energy and the growth of various domestic and industrial electricity consumptions, as well as the grid connection of new energy power generations of various scales, the power plant equipment of the two major power sources of the national power grid (thermal power generation and hydropower generation) needs to respond more promptly to the random real-time regulation requirements of the grid output.

[0003] In the large power systems and large industries, although various amplitude modulation and frequency modulation compensation systems using external energy storage media have been rapidly applied in recent years, which can relieve the real-time regulation pressure of power plants to a certain extent. However, on the one hand, existing devices are all large compensation devices, and their construction is more or less restricted by conditions. On the other hand, due to the existence of line resistance in the power transmission line, as the transmission distance increases, both the instantaneous power and the continuous power will be attenuated to a certain extent, and the amplitude loss phenomenon is also common at the far end. Moreover, especially in various industrial electricity consumption links, in order to control costs, most of the electrical equipment at all levels does not design a power factor improvement circuit. Therefore, the reactive power loss in the power transmission of the national power grid is very large, and the overall power utilization rate is very low.

[0004] For example, a pole-mounted rural power grid low-voltage comprehensive improvement device disclosed in Patent No. CN201620213569.0 can improve the power factor in the system, but it does not convert and store reactive power and needs to charge the voltage compensation module additionally, increasing the user's usage cost. Content of the Utility Model

[0005] An object of the utility model is to solve at least the above problems and / or defects and provide at least the advantages described hereinafter.

[0006] To achieve these objects and other advantages according to the utility model, a grid AC compensation and power factor improvement system based on super capacitors is provided, including: a three-phase circuit, and further including: a system detection and control unit electrically connected to the output end and the input end of the three-phase circuit;

[0007] A power factor improvement unit and an AC compensation unit electrically connected to the three-phase circuit through a conversion inductor and cooperating with the system detection and control unit;

[0008] A system power supply electrically connected to the power factor improvement unit and the AC compensation unit;

[0009] The power factor improvement unit includes: a three-phase PFC module, and the output terminals of the three-phase PFC module are respectively electrically connected to a system power supply, a transducer inductor, a system detection and control unit, and an AC compensation unit;

[0010] The AC compensation unit includes: a three-phase inverter module, a buck-boost bidirectional conversion module, a storage inductor, and a supercapacitor module;

[0011] The output terminals of the three-phase inverter module are respectively electrically connected to a transducer inductor, a system power supply, a three-phase PFC module, a buck-boost bidirectional conversion module, and a system detection and control unit. The output terminals of the buck-boost bidirectional conversion module are respectively electrically connected to a storage inductor and a system detection and control unit. The output terminal of the storage inductor is electrically connected to the supercapacitor module, and the supercapacitor module is connected to the system detection and control unit. Preferably,

[0012] Preferably, it further includes: a filter capacitor disposed between the storage inductor and the supercapacitor energy storage module.

[0013] Preferably, the three-phase inverter module is configured as a six-tube three-phase inverter circuit.

[0014] Preferably, the three-phase PFC module is configured to include any one of a three-phase Vienna PFC circuit, a three-phase bridgeless PFC circuit, and a BOOST boost PFC circuit.

[0015] Preferably, the filter capacitor is configured to include any one of an electrolytic capacitor and a thin film capacitor.

[0016] Preferably, the filter capacitor adopts a series connection mode of electrolytic capacitors.

[0017] Preferably, the system detection and control unit is configured to include: an AC detection circuit for detecting an external power grid, a DC detection circuit for detecting the inside of the compensation and improvement unit, a DSP control module, and a drive / PWM interlock circuit. The output terminal of the AC detection circuit is respectively electrically connected to the output terminal and the input terminal of the three-phase circuit and the DSP control module. The output terminal of the drive / PWM interlock circuit is respectively connected to the three-phase PFC module, the three-phase inverter module, and the DSP control module. The output terminal of the DC detection circuit is respectively connected to the DSP control module, the buck-boost bidirectional conversion module, and the supercapacitor module;

[0018] The DSP control unit is configured to adopt TMS32F280025.

[0019] Preferably, the system power supply is configured to adopt a switching type high-frequency switching circuit.

[0020] Preferably, the supercapacitor module is configured to be obtained by connecting a plurality of 2.7V supercapacitor monomers in series.

[0021] Preferably, the system detection and control unit further includes a display module and a wireless communication module connected to the DSP control module.

[0022] The present utility model has at least the following beneficial effects: The present utility model improves the power factor of the power consumption terminal through the mutual cooperation of the power factor improvement unit and the AC compensation unit. On the other hand, it provides a short-term emergency AC power supply when the power grid is powered off, protects some relatively important power-consuming devices, and at the same time saves the power consumption cost for the users of the power consumption terminal.

[0023] Other advantages, objectives, and features of the present utility model will be partially reflected by the following description and partially understood by those skilled in the art through the research and practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram of the system composition of the present utility model;

[0025] Figure 2 It is a simplified circuit diagram of the system connection of the present utility model;

[0026] Figure 3 It is a block diagram of the composition of the system detection and control unit of the present utility model;

[0027] Figure 4 It is a schematic block diagram of the connection of the system of the present utility model with a three-phase circuit and a load device.

[0028] Reference numerals in the drawings: 1, three-phase circuit; 2, transducer inductor; 3, three-phase inverter module; 4, three-phase PFC module; 5, buck-boost bidirectional conversion module; 6, system power supply; 7, energy storage inductor; 8, filter capacitor; 9, supercapacitor module; 10, system detection and control unit; 101, DSP control module; 102, AC detection circuit; 103, drive / PWM interlock circuit; 104, DC detection circuit; 105, display module; 106, wireless communication module. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following further describes the present utility model in detail with reference to the drawings, so that those skilled in the art can implement it according to the description in the specification.

[0030] It should be understood that the terms such as "having", "comprising", and "including" used herein do not exclude the presence or addition of one or more other elements or their combinations.

[0031] It should be noted that in the description of the present utility model, the orientation or positional relationship indicated by the terms is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0032] In the description of the present utility model, unless otherwise clearly specified and defined, the terms "installed", "provided with", "sheathed / connected", "connected", etc. shall be understood in a broad sense. For example, "connected" 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. It can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific situations.

[0033] In addition, in the present utility model, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0034] Figure 1 A power grid AC compensation and power factor improvement system based on a supercapacitor of the present utility model is shown, including: a three-phase circuit 1, and further including: a system detection and control unit 10 electrically connected to the output end and the input end of the three-phase circuit 1;

[0035] A power factor improvement unit electrically connected to the three-phase circuit 1 through a transducer inductor 2 and cooperating with the system detection and control unit 10;

[0036] An AC compensation unit electrically connected to the three-phase circuit 1 through a transducer inductor 2 and cooperating with the system detection and control unit 10;

[0037] A system power supply 6 electrically connected to the power factor improvement unit and the AC compensation unit;

[0038] The power factor improvement unit includes: a three-phase PFC module 4, and the output ends of the three-phase PFC module 4 are respectively electrically connected to the system power supply 6, the transducer inductor 2, the system detection and control unit 10 and the AC compensation unit;

[0039] The AC compensation unit includes: a three-phase inverter module 3, a buck-boost bidirectional conversion module 5, a storage inductor 7, and a supercapacitor module 9;

[0040] The output terminals of the three-phase inverter module 3 are respectively electrically connected to the transducer inductor 2, the system power supply 6, the three-phase PFC module 4, the buck-boost bidirectional conversion module 5, and the system detection and control unit 10. The output terminals of the buck-boost bidirectional conversion module 5 are respectively electrically connected to the storage inductor 7 and the system detection and control unit 10. The output terminal of the storage inductor 7 is electrically connected to the supercapacitor module 9, and the supercapacitor module 9 is connected to the system detection and control unit 10.

[0041] Working principle:

[0042] During the working process, the system power supply 6 supplies power to the internal system detection and control unit 10, the power factor improvement unit, and the AC compensation unit. At the same time, the three-phase alternating current input through the three-phase input terminals passes through the system detection and control unit 10. In this link, the system detects the unprocessed three-phase AC frequency, the phase of each phase current, and the current within the cycle of the power grid, and the system detection and control unit 10 analyzes the deformed envelope of its sine current to provide basis parameters for system compensation. The system works in the compensation state and the power factor improvement state in different phase angle intervals within the same cycle. When the system works in the compensation state, the transducer inductor 2 acts as the three-phase inverter output inductor, combines with the output capacitor to perform integral processing on the inverter SPWM power wave, and then superimposes the integrated quasi-sine energy on the three-phase AC waveform and outputs it through the three-phase output terminals to provide power for the electrical equipment. In the three-phase output current detection circuit, the three-phase AC frequency, the phase of each phase current, and the current within the cycle that have been compensated are detected again. Similarly, the system detection and control unit 10 analyzes the envelope of its sine current. Through the above loop, a closed-loop compensation adjustment loop is formed. The AC compensation unit is analyzed and controlled through the system detection and control unit 10 in cooperation with software. At the same time, the electric energy stored in the supercapacitor module is boosted by the storage inductor 7 and the buck-boost bidirectional conversion circuit to provide output energy for the DC bus of the three-phase inverter circuit. When the system works in the power factor improvement state, the transducer inductor 2 acts as the PFC boost inductor. The system boosts the energy in the phase interval with a low PFC value according to the anti-sine law based on the detection of the phase and angle values of the input AC current. The boosted DC high voltage is then subjected to current limiting and voltage limiting processing through the buck-boost bidirectional conversion and the storage inductor 7 and stored in the supercapacitor module. When the current phase angle in the three-phase circuit 1 transitions to the compensation angle interval, this energy is applied in the reverse direction.

[0043] Meanwhile, according to the actual working requirements, the capacity of the supercapacitor module is configured to be relatively large. The system can operate in the AC emergency power supply mode. When the system detects a power outage in the three-phase power grid, the energy in the supercapacitor module stabilizes the internal DC voltage at about 600V through the energy storage inductor 7 and the buck-boost bidirectional conversion circuit, and then converts the DC voltage into an AC voltage through the three-phase inverter circuit and the transducer inductor 2 to continue supplying power to the electrical equipment.

[0044] The capacity of the supercapacitor module is configured to be large enough. The system can operate in the power grid frequency compensation mode. When the system detects that the power grid frequency is normal or high, the power grid energy is stored in the supercapacitor module inside the system. When the system detects that the power grid frequency is low, the energy stored in the internal high-voltage supercapacitor module is inverted and connected to the power grid to reduce the burden on the power plant.

[0045] In the above technical solution, it further includes: a filter capacitor 8 disposed between the energy storage inductor 7 and the supercapacitor energy storage module. With this technical solution, the filter capacitor 8 can filter out high-frequency noise and harmonics in the current between the energy storage inductor 7 and the supercapacitor. When the current flows from the energy storage inductor 7 to the supercapacitor, due to the impedance characteristics of the inductor, the high-frequency components in the current will be suppressed by the inductor, but some high-frequency noise may still pass through. At this time, the filter capacitor 8 uses its low impedance characteristic (for high-frequency signals) to provide a low-impedance bypass channel for these high-frequency noises, enabling them to bypass the supercapacitor and directly flow back to the power supply or ground, thereby achieving the filtering effect. The filter capacitor 8 can also stabilize the voltage across the supercapacitor to a certain extent. During the change of the power grid load or the charging and discharging process of the supercapacitor, the voltage may fluctuate. The filter capacitor 8 can slow down this fluctuation to a certain extent by storing and releasing charges, making the voltage across the supercapacitor more stable.

[0046] In the above technical solution, the three-phase inverter module 3 is configured as a six-switch three-phase inverter circuit. With this technical solution, the six-switch three-phase inverter circuit is a commonly used power electronic conversion circuit, which mainly consists of six power switch devices (such as IGBTs, MOSFETs, etc.). These switch devices convert direct current (DC) into three-phase alternating current (AC) through appropriate control strategies. Each power switch device is connected to an anti-parallel diode to provide a reverse current path.

[0047] In the six-switch three-phase inverter circuit, usually the positive and negative poles of the DC power supply are respectively connected to the two endpoints of the circuit, and the three output terminals are respectively connected to the three-phase load or the power grid. By controlling the on-off states of the six switch devices, precise control of the amplitude, frequency, and phase of the output three-phase voltage can be achieved.

[0048] In the above technical solution, the three-phase PFC module 4 is configured to include any one of a three-phase Vienna PFC circuit, a three-phase bridgeless PFC circuit, and a BOOST boost PFC circuit. With this technical solution, the three-phase Vienna PFC circuit has the following characteristics:

[0049] High efficiency: The three-phase Vienna PFC circuit usually has a high conversion efficiency because it reduces the number of switching devices required in traditional PFC circuits and decreases the conduction loss.

[0050] Low harmonics: This circuit can generate a relatively pure current waveform, reducing harmonic pollution in the power grid.

[0051] Good thermal management: Since the number of switching devices is small and it is usually designed with a good heat dissipation structure, thermal management is relatively simple. Compared with the traditional bridged PFC circuit, the bridgeless PFC circuit further reduces the conduction loss and improves the overall efficiency by reducing the number of rectifier diodes. The BOOST boost PFC circuit has characteristics such as flexible regulation and high reliability. In actual work, the appropriate circuit can be selected according to the actual application scenario and performance requirements.

[0052] In the above technical solution, the filter capacitor 8 is configured to include any one of an electrolytic capacitor and a thin film capacitor. With this technical solution, by selecting an electrolytic capacitor or a thin film capacitor as the filter capacitor 8, it can be optimized according to the specific requirements of the system. For example, in cases where a large capacitance filter is required and cost is a concern, an electrolytic capacitor can be selected; while in cases where high stability and long life are required, a thin film capacitor can be chosen. In addition, the most suitable type of filter capacitor 8 can be selected by comprehensively considering factors such as the voltage level, current characteristics, and working environment of the system.

[0053] In the above technical solution, the filter capacitor 8 adopts a series connection of electrolytic capacitors. With this technical solution, electrolytic capacitors usually have a large capacitance, which enables them to store more charge in filtering applications, thus more effectively filtering out low-frequency noise and fluctuations. By connecting multiple electrolytic capacitors in series, the withstand voltage capacity of the entire capacitor combination can be significantly improved. At the same time, in a series circuit, each capacitor will share a part of the voltage. If the parameters such as the capacitance and leakage current of the capacitors are properly matched, the voltage distribution will be relatively balanced, which is beneficial to extending the service life of the capacitors and improving the stability of the system. Multiple series-connected filter capacitors 8 can also improve the filtering efficiency.

[0054] In the above technical solution, the system detection and control unit 10 is configured to include: an AC detection circuit 102 for detecting the external power grid, a DC detection circuit 104 for detecting the inside of the compensation and boost unit, a DSP control module 101, and a drive / PWM interlock circuit 103. The output end of the AC detection circuit 102 is electrically connected to the output end and the input end of the three-phase circuit 1 and the DSP control module 101 respectively. The output end of the drive / PWM interlock circuit 103 is electrically connected to the three-phase PFC module 4, the three-phase inverter module 3, and the DSP control module 101 respectively. The output end of the DC detection circuit 104 is electrically connected to the DSP control module 101, the buck-boost bidirectional conversion module 5, and the supercapacitor module 9 respectively;

[0055] The DSP control unit is configured to use TMS32F280025. With this technical solution, the AC detection circuit 102 is responsible for detecting parameters such as the three-phase AC frequency of the external power grid and the phase of each phase current, ensuring that the system can perceive the power grid state in real time. The AC detection circuit 102 is connected to the output end and the input end of the three-phase circuit 1 and the DSP control module 101, enabling the DSP control module 101 to obtain real-time power grid data and then adjust the control strategy. The DC detection circuit 104 detects parameters such as the DC voltage and current inside the buck-boost bidirectional conversion module 5 and the supercapacitor module 9, and its output end is connected to the DSP control module 101, providing real-time feedback on the internal DC state of the system. The DSP control module 101 outputs signals to control the buck-boost bidirectional conversion module 5 and the supercapacitor module 9 to realize the charging and discharging of the supercapacitor module 9. The DSP control module 101 (TMS32F280025) serves as the core control unit of the system. TMS32F280025 DSP provides high-performance computing capabilities and rich peripheral interfaces. It receives data from the AC detection circuit 102 and the DC detection circuit 104, and executes complex control algorithms such as power factor correction (PFC), inverter control, and power management. At the same time, the DSP is also responsible for generating drive / PWM signals and controlling execution elements such as the three-phase PFC module 4 and the three-phase inverter module 3 through the drive / PWM interlock circuit 103. The drive / PWM interlock circuit 103 is responsible for converting the PWM signals generated by the DSP into signals that can drive power electronic devices (such as IGBTs, MOSFETs, etc.).

[0056] In the above technical solution, the system power supply 6 is configured to use a switching-type high-frequency switching circuit. With this technical solution, the system power supply 6 using a switching-type high-frequency switching circuit has excellent characteristics such as high efficiency, miniaturization, stable and reliable operation, and a wide voltage adjustment range.

[0057] In the above technical solution, the supercapacitor module 9 is configured to be obtained by connecting multiple 2.7V supercapacitor monomers in series. By adopting this technical solution, the technical solution of connecting multiple supercapacitor monomers in series also endows the supercapacitor module 9 with higher flexibility and scalability. According to the specific requirements of the system, the number of monomers in series can be conveniently adjusted to change the rated voltage and energy storage capacity of the module. This flexibility enables the supercapacitor module 9 to be more widely applied to various different power electronic systems.

[0058] In the above technical solution, the system detection and control unit 10 further includes: a display module 105 and a wireless communication module 106 connected to the DSP control module 101. By adopting this technical solution, the display module 105 (such as an LCD display screen or an LED indicator) can display the data, status information, or fault alarms detected by the system in real time. This is extremely important for the operators because it provides intuitive and immediate feedback, enabling them to quickly understand the current working condition of the system and thus make corresponding adjustments or interventions. The addition of the wireless communication module 106 (such as Wi-Fi, Bluetooth, Zigbee, 4G / 5G, etc.) enables the system to communicate wirelessly with other devices or a remote monitoring center. And the system accepts the unified control instructions of the State Grid.

[0059] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the description and the embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily achieved. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated and described examples here.

Claims

1. A supercapacitor-based power grid AC compensation and power factor improvement system, comprising: The three-phase circuit is characterized in that it also includes: a system detection control unit electrically connected to the output end and the input end of the three-phase circuit; A power factor improvement unit and an AC compensation unit which are electrically connected to the three-phase circuit through a transducer inductor and cooperate with a system detection control unit; A system power supply electrically connected to the power factor improvement unit and the AC compensation unit; The power factor improvement unit comprises: a three-phase PFC module, the output end of which is electrically connected to a system power supply, a transducer inductor, a system detection control unit and an AC compensation unit respectively; The AC compensation unit includes: a three-phase inverter module, a buck-boost bidirectional conversion module, an energy storage inductor, and a supercapacitor module; The output end of the three-phase inverter module is electrically connected to the transducer inductor, the system power supply, the three-phase PFC module, the buck-boost bidirectional conversion module and the system detection control unit respectively; the output end of the buck-boost bidirectional conversion module is electrically connected to the energy storage inductor and the system detection control unit respectively; the output end of the energy storage inductor is electrically connected to the supercapacitor module, and the supercapacitor module is connected to the system detection control unit.

2. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: Also includes: A filter capacitor is arranged between the energy storage inductor and the supercapacitor energy storage module.

3. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: The three-phase inverter module is configured as a six-tube three-phase inverter circuit.

4. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: The three-phase PFC module is configured to include any one of a three-phase Vienna PFC circuit, a three-phase bridgeless PFC circuit and a BOOST boost PFC circuit.

5. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 2, characterized in that: The filter capacitor is configured to include any one of an electrolytic capacitor and a film capacitor.

6. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 5, characterized in that: The filter capacitor adopts the electrolytic capacitor series connection mode.

7. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: The system detection control unit is configured to include: an AC detection circuit for detecting an external power grid, a DC detection circuit for detecting the inside of a compensation and lifting unit, a DSP control module, and a drive / PWM interlocking circuit. The output end of the AC detection circuit is electrically connected to the output end and the input end of the three-phase circuit and the DSP control module, respectively. The output end of the drive / PWM interlocking circuit is connected to a three-phase PFC module, a three-phase inverter module, and a DSP control module, respectively. The output end of the DC detection circuit is connected to the DSP control module, a buck-boost bidirectional conversion module, and a supercapacitor module, respectively. The DSP control module is configured to adopt TMS32F280025.

8. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: It is characterized in that The system power supply is configured to employ a switch-type high frequency switching circuit.

9. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 1, characterized in that: The super capacitor module is configured to include a plurality of 2.7V super capacitor cells connected in series.

10. The supercapacitor-based grid AC compensation and power factor improvement system according to claim 7, characterized in that: The system detection control unit also includes: a display module and a wireless communication module connected to the DSP control module.

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