Harmonic filter, bidirectional full-bridge converter and new energy station harmonic suppression device

Abstract

The utility model discloses a harmonic filter, a bidirectional full-bridge converter and a new energy station harmonic suppression device. The harmonic filter comprises a first capacitor and a tuning loop unit which are connected in parallel. The tuning loop unit comprises a second capacitor, an autotransformer, a switching tube and a low-voltage side resistor; the second capacitor is connected in series with the high-voltage side of the autotransformer and then is connected in parallel with the first capacitor; the collector of the switching tube is connected with one end of the low-voltage side of the autotransformer, one end of the low-voltage side resistor is connected with the other end of the low-voltage side of the autotransformer, the emitter of the switching tube is connected with the other end of the low-voltage side resistor and grounded, and the base of the switching tube receives a switching control signal. Through the synergistic effect of the first capacitor and the tuning loop unit, especially the tuning loop unit forms a low-impedance loop corresponding to the harmonic waves of the power distribution network, and in combination with the dynamically adjustable switch tube, the harmonic waves generated in the working process of the bidirectional full-bridge converter are efficiently suppressed.

Description

TECHNICAL FIELD

[0001] The utility model relates to new energy control technical field especially relates to a harmonic filter, bidirectional full -bridge converter and new energy station harmonic treatment device. BACKGROUND

[0002] With the development of the power electronic trend of power grid, a large number of power electronic equipment appears in the power grid, and the harmonics generated by them inject the power grid, so that the harmonic problem of the power grid is increasingly serious.At present, the harmonic problem is gradually highlighted in the engineering practice of China and the world, and the attention of the power grid company is aroused, but how to effectively predict, calculate the influence of background harmonic and effectively solve the influence of background harmonic is still relatively less.Harmonic transmission in the power system will seriously affect the power supply quality of the power system, and in serious cases, it may cause damage to the user or power grid equipment, therefore, the equipment generating large harmonics usually needs to be configured with a filter device in the power grid.The filter device is mainly divided into two types at present, one is a passive filter device, that is, fixed capacitors, inductors and resistors are adopted, and through certain series and parallel connection, impedance low point of fixed tuning frequency is formed to achieve the effect of filtering.The other is an active filter device, that is, pure power electronic equipment is adopted, and through detecting the harmonic level of the power grid, the active filter device generates opposite-phase harmonics to filter out the harmonics.

[0003] In the new energy station, the harmonic treatment measures mainly rely on the filter function of SVG, but with the increase of the capacity of the new energy station, it is difficult to meet the demand of system harmonic control by relying on the filter of SVG only, and it is necessary to seek multiple filtering means to comprehensively solve the harmonic problem of the new energy station.

[0004] The existing scheme mainly exists two kinds, one is to adopt STATCOM for filtering, and the effect of adopting STATCOM for filtering is relatively good, that is, it can meet the requirements of reactive power compensation of the new energy station and can meet the demand of reactive power;But the capacity of STATCOM in the new energy station is relatively small, and in some cases, it cannot meet the demand of filtering;The other is an active power filter, and the active power filter has good filtering effect on harmonics, but the cost of the equipment is relatively high, and it needs to be invested separately, which causes great waste. SUMMARY

[0005] The utility model discloses a kind of harmonic filter, bidirectional full -bridge converter and new energy station harmonic treatment device, and the purpose of the embodiment of the utility model is to provide, by the synergistic effect of first capacitor and tuning loop unit, especially tuning loop unit forms corresponding low impedance loop with distribution network harmonic, and combined with dynamically adjustable switch tube, the harmonic generated in the work of bidirectional full -bridge converter is efficiently suppressed, the power quality is greatly improved, and the adverse effects on full -bridge assembly and distribution network are reduced.

[0006] To solve the above technical problems, the first aspect of the utility model embodiment provides a harmonic filter, comprising: a first capacitor and a tuning loop unit connected in parallel;

[0007] The tuning loop unit comprises: a second capacitor, an autotransformer, a switching tube and a low-voltage side resistor;

[0008] The second capacitor is connected in series with the high-voltage side of the autotransformer and then connected in parallel with the first capacitor;

[0009] The collector of the switching tube is connected with one end of the low-voltage side of the autotransformer, one end of the low-voltage side resistor is connected with the other end of the low-voltage side of the autotransformer, the emitter of the switching tube is connected with the other end of the low-voltage side resistor and grounded, and the base of the switching tube receives a switching control signal.

[0010] Further, the harmonic filter further comprises: a lightning arrester;

[0011] The lightning arrester is connected in parallel with the first capacitor.

[0012] Further, the reactance value of the output end of the switching tube is related to the duty cycle of the control signal received by the base of the switching tube.

[0013] Further, the type of the first capacitor comprises: an aluminum electrolytic capacitor, a tantalum capacitor, a polymer capacitor and a thin film capacitor.

[0014] Further, the type of the second capacitor comprises: a variable capacitor, a voltage variable capacitor, a ceramic capacitor, a thin film capacitor, a super capacitor, a trimmer capacitor, a MEMS capacitor and a mica capacitor.

[0015] Further, the tuning loop unit is a low-impedance loop corresponding to the harmonic of the power distribution network.

[0016] Correspondingly, the second aspect of the utility model embodiment provides a bidirectional full-bridge converter, comprising: a full-bridge assembly, and further comprising the harmonic filter;

[0017] One end of the harmonic filter is connected with the midpoint of one half-bridge arm of the full-bridge assembly, and the other end of the harmonic filter is connected with the midpoint of the other half-bridge arm of the full-bridge assembly.

[0018] Correspondingly, the third aspect of the utility model embodiment provides a new energy station harmonic control system, comprising the plurality of bidirectional full-bridge converters; the three-phase connection mode of the energy storage device and the new energy station power distribution network is Y type, and the number of the bidirectional full-bridge converters in each phase is the same and is a preset number.

[0019] The above technical scheme of the embodiment of the utility model has the following beneficial technical effects:

[0020] 1. Through the cooperation of the first capacitor in the harmonic filter and the tuning loop unit, especially the low-impedance loop corresponding to the harmonic of the power distribution network formed by the tuning loop unit, the harmonic current can be effectively guided to flow into the filter, greatly reducing the adverse effects of the harmonics generated by the bidirectional full-bridge converter in the working process on the full-bridge assembly and the power distribution network, and improving the power quality.

[0021] 2. The integrated design of the harmonic filter reduces the interference of harmonics on the main circuit, reduces electromagnetic interference and voltage fluctuation in the system, enhances the stability of the entire system, and reduces the risk of equipment failure.

[0022] 3. It can be adjusted and optimized according to different application scenarios and power distribution network requirements, adapt to different harmonic characteristics and power quality requirements, and has wide application prospects in new energy, smart grid and industrial fields. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the principle diagram of the harmonic filter provided by the embodiment of the utility model;

[0024] Figure 2 is the principle diagram of the new energy station harmonic treatment device provided by the embodiment of the utility model. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the utility model more clear and explicit, the utility model is further described in detail below in combination with specific implementation manners and with reference to the drawings. It should be understood that these descriptions are only exemplary and do not limit the scope of the utility model. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the utility model.

[0026] Please refer to Figure 1 The first aspect of the embodiment of the utility model provides a harmonic filter, which comprises: a first capacitor and a tuning loop unit connected in parallel; the tuning loop unit comprises: a second capacitor, an autotransformer, a switching tube and a low-voltage side resistor; the second capacitor is connected in series with the high-voltage side of the autotransformer and then connected in parallel with the first capacitor; the collector of the switching tube is connected with one end of the low-voltage side of the autotransformer, one end of the low-voltage side resistor is connected with the other end of the low-voltage side of the autotransformer, the emitter of the switching tube is connected with the other end of the low-voltage side resistor and grounded, and the base of the switching tube receives a switching control signal.

[0027] The first capacitor in the harmonic filter mainly absorbs power frequency energy to stabilize the voltage of the energy storage device. By connecting the first capacitor and the tuning loop unit in parallel, a low impedance path can be provided for specific harmonic frequencies, allowing the harmonics to be effectively guided into the ground or bypassed, thereby reducing the impact of harmonics on the main circuit. In addition, the presence of harmonics increases the thermal loss and mechanical stress of power equipment. By reducing the impact of harmonics, the harmonic filter helps to prolong the service life of the equipment and reduce maintenance costs.

[0028] Through the fine design of the tuning loop unit, efficient filtering of specific harmonic frequencies in the new energy station is achieved. The series connection of the second capacitor and the high-voltage side of the autotransformer, combined with the parallel configuration of the first capacitor, forms a low-impedance path for specific harmonic frequencies, effectively guiding these harmonics to the ground or bypass, thereby reducing the impact on the main circuit. The autotransformer serves as a voltage transformer and impedance matching in the circuit. Through the series connection of its high-voltage side and the second capacitor, and the connection of its low-voltage side with the switch tube and low-voltage side resistor, it achieves adaptation to different voltage levels and transfer and suppression of harmonics. The base of the switch tube receives a switching control signal, which determines the conduction and cutoff of the switch tube according to the state of the control signal. When the switch tube is on, the low-voltage side of the autotransformer forms a loop through the switch tube and the low-voltage side resistor, changing the impedance characteristics of the circuit and adjusting the suppression effect of the filter on harmonics. When the switch tube is off, the loop is disconnected and the working state of the filter also changes accordingly; the introduction of the switch tube, regulated by the control system of the new energy station, provides dynamic adjustment capability for the system to adapt to changing grid conditions and harmonic characteristics. The low-voltage side resistor provides effective damping for the system to avoid harmonic amplification and attenuation difficulties caused by resonance.

[0029] The harmonic filter is designed for the full-bridge topology of the energy storage device and the power distribution network connection in the new energy station, which can effectively suppress the harmonics generated in this specific scenario; by receiving a switching control signal through the switch tube, the working state of the filter can be dynamically adjusted according to the actual situation, improving the adaptability and flexibility of the filter. It is composed of a parallel first capacitor and a tuning loop unit containing multiple elements, with a relatively simple and compact structure, making it easy to install and use in full-bridge modules. The above implementation not only improves the power quality of the new energy station, but also enhances the system's control ability over harmonics, thereby improving the stability and reliability of the entire power system.

[0030] Further, the harmonic filter further comprises: an arrester; and the arrester is connected in parallel with the first capacitor.

[0031] In the energy storage device, the technical solution of connecting the lightning arrester in parallel with the first capacitor can provide multiple technical effects. Such configuration not only enhances the protection capability of the system against lightning impact and operating overvoltage, but also ensures that the lightning arrester remains in a high resistance state under normal operating voltage, reducing interference to system operation. When overvoltage occurs, the lightning arrester quickly changes to a low resistance state, effectively guiding the overvoltage current to the ground, thereby protecting the energy storage device from damage and maintaining the safe and stable operation of the system. In addition, this design helps to improve the reliability of the energy storage device and prolong the service life of the equipment, while also protecting the safety of operating personnel, reducing equipment failure and maintenance costs caused by overvoltage.

[0032] Further, the reactance value of the switch tube output end is related to the duty cycle of the control signal received by its base.

[0033] In the harmonic control device of the new energy station, by associating the reactance value of the switch tube with the duty cycle of the control signal received by its base, dynamic adjustment of the reactance value is achieved. The above implementation allows the system to flexibly adjust the reactance value according to real-time grid conditions and harmonic conditions to optimize harmonic filtering effect. When the duty cycle of the control signal changes, the on and off state of the switch tube changes accordingly, thereby changing the reactance characteristics of the circuit.

[0034] When the duty cycle is high, the switch tube is on for a long time, and the reactance value is small, allowing more current to pass through; when the duty cycle is low, the switch tube is on for a shorter time, and the reactance value increases, limiting the passage of current, especially the suppression of high-frequency harmonic components. Such dynamic adjustment capability enables the new energy station to more accurately control and reduce harmonic pollution in the power grid, thereby improving power quality and enhancing the stability and reliability of the power grid.

[0035] Further, the types of the first capacitor include aluminum electrolytic capacitor, tantalum capacitor, polymer capacitor and thin film capacitor.

[0036] The first capacitor has multiple optional types, such as aluminum electrolytic capacitor, tantalum capacitor, polymer capacitor and thin film capacitor. Aluminum electrolytic capacitors are commonly used in power supply filtering due to their high capacitance value and small size; tantalum capacitors are widely used in precision electronics due to their low ESR and high reliability; polymer capacitors, such as conductive polymer aluminum electrolytic capacitors, provide low ESR, stable temperature characteristics and long service life, suitable for ripple absorption and transient response; thin film capacitors are suitable for high-frequency circuits due to their good temperature and voltage characteristics. The use of these capacitors or the parallel use of two or more of them enhances the system's ability to filter different frequency and amplitude harmonics, improves the power quality and system stability of the new energy station, and also provides the system with higher reliability and longer service life.

[0037] Further, the types of the second capacitors include variable capacitors, voltage variable capacitors, ceramic capacitors, thin film capacitors, super capacitors, trimmer capacitors, MEMS capacitors, and mica capacitors.

[0038] By adopting multiple types of second capacitors such as variable capacitors, voltage variable capacitors, ceramic capacitors, thin film capacitors, super capacitors, trimmer capacitors, MEMS capacitors, and mica capacitors, different frequencies and amplitudes of harmonics can be accurately filtered out. These capacitors, due to their unique physical characteristics and electrical properties, can provide the required capacitance and stability in the tuning circuit, thereby optimizing the filtering characteristics and improving the power quality and system stability of the new energy station. For example, variable and voltage variable capacitors can dynamically adjust their capacitance to adapt to changes in grid conditions; ceramic and thin film capacitors are suitable for filtering high-frequency harmonics due to their high-frequency characteristics; super capacitors perform well in energy storage and instantaneous harmonic absorption due to their large capacity and fast charging and discharging characteristics; trimmer capacitors and MEMS capacitors provide fine tuning capabilities for the system to match specific harmonic frequencies; and mica capacitors maintain performance in high-voltage applications due to their high stability and voltage resistance. The diversity of capacitor configurations enables the harmonic control device to be more flexible and efficient in dealing with complex grid environments, ensuring stable operation and optimized power quality of the new energy station.

[0039] Further, the tuning circuit unit is a low-impedance circuit corresponding to the harmonics of the distribution network. The tuning circuit unit can more effectively form a low-impedance state for specific harmonic frequencies in the distribution network. When harmonic currents occur, due to the presence of the low-impedance circuit, harmonic currents will preferentially flow into the tuning circuit unit rather than circulating in the main circuit. This can greatly reduce the impact of harmonic currents on energy storage devices and other equipment in the distribution network. The autotransformer can more efficiently achieve voltage transformation and impedance matching in the low-impedance circuit. It can adjust the harmonic voltage to a level suitable for the tuning circuit unit to handle, while further limiting the circulation of harmonic currents through its own impedance characteristics. The switching tube receives a switching control signal and can more accurately adjust the impedance state of the circuit in the low-impedance circuit. By controlling the conduction and cutoff of the switching tube, the parameters of the low-impedance circuit can be dynamically adjusted according to the actual harmonic conditions, achieving more effective suppression of harmonics.

[0040] Correspondingly, please refer to Figure 2 The second aspect of the utility model embodiment provides a bidirectional full-bridge converter, include: full-bridge subassembly, still include above-mentioned harmonic filter, harmonic filter one end with the midpoint of one half bridge arm in full-bridge subassembly is connected, its other end with the midpoint of another half bridge arm in full-bridge subassembly is connected.

[0041] The full-bridge assembly is generally composed of power switching devices for realizing bidirectional conversion of electric energy. The first capacitor in the harmonic filter and the tuning loop unit work together with the full-bridge assembly to jointly complete efficient conversion of electric energy and effective suppression of harmonics. When electric energy is converted in the full-bridge assembly, harmonics may be generated, and the harmonic filter arranged in the full-bridge assembly begins to play a role. The harmonic filter can effectively suppress the harmonics that may be generated in the bidirectional full-bridge converter; by forming a low-impedance loop corresponding to the harmonics of the power distribution network, the harmonic current is guided to flow into the filter, thereby reducing the harm of harmonics to the full-bridge assembly and the power distribution network.

[0042] Correspondingly, please refer to Figure 2 The third aspect of the embodiments of the utility model provides a new energy station harmonic treatment system, including above-mentioned several bidirectional full-bridge converter;The three-phase connection mode of energy storage device and new energy station power distribution network is Y type, and the number of bidirectional full-bridge converter in each phase is same and is preset number.

[0043] The above-mentioned new energy station harmonic treatment device based on energy storage device realizes effective filtering of harmonics and improvement of power quality through full-bridge structure and Y type connection mode, in combination with the setting of energy storage battery pack. The device sets full-bridge module in each phase, and is correspondingly arranged with filter assembly and is connected in parallel, thereby enhancing the suppression ability of harmonics in the power grid and reducing the total harmonic distortion (THD) of the power grid.

[0044] Meanwhile, the energy storage device stores and releases electric energy to balance the power grid load and cope with the volatility of new energy generation, thereby improving the consumption capacity of new energy and enhancing the stability and reliability of the power grid. In addition, the device can also reduce the efficiency reduction, life shortening and possible damage risk of power equipment caused by harmonics, thereby improving the operation efficiency and economy of the entire new energy station.

[0045] In addition, the number of bidirectional full-bridge converters is determined by the voltage level of the system. The energy storage battery pack is connected in parallel between the positive DC bus and the negative DC bus as the energy storage element of the system. The filter assembly is connected in parallel in each full-bridge structure, and the above structure can keep the relative independence of the battery and the harmonic filter in the bidirectional full-bridge converter, and the battery does not need to bear the harmonic stress, which has no effect on the operation of the battery; at the same time, the real-time online of the filtering function is maintained, and it is not necessary to be limited by whether the battery is charged or not, and the structure is relatively simple.

[0046] In new energy stations, the use of harmonic control devices based on energy storage devices can significantly improve the power quality and stability of the power system. This device integrates multiple types of capacitors, such as aluminum electrolytic capacitors, tantalum capacitors, polymer capacitors, and thin-film capacitors, and is connected in parallel with a lightning arrester, effectively filtering out various frequencies and amplitudes of harmonics in the power grid. This comprehensive technical solution not only improves power quality and reduces total harmonic distortion (THD) in the power grid, but also enhances the system's control ability over harmonics, reducing the risk of reduced efficiency, shortened lifespan, and possible damage to power equipment caused by harmonics. At the same time, by dynamically adjusting the reactance value, the system can flexibly respond to changes in power grid conditions, optimize harmonic filtering effects, and improve the power quality and system stability of new energy stations, while providing higher reliability and longer service life for the system.

[0047] The utility model embodiment aims at protecting a kind of harmonic filter, bidirectional full-bridge converter and new energy station harmonic control device, harmonic filter includes: the parallel connection of first capacitor and tuning circuit unit;Tuning circuit unit includes: second capacitor, autotransformer, switch tube and low-voltage side resistance;Second capacitor is connected in series with autotransformer high-voltage side and is connected in parallel with first capacitor;The collector of switch tube is connected with the low-voltage side one end of autotransformer, and one end of low-voltage side resistance is connected with the low-voltage side other end of autotransformer, and the emitter of switch tube is connected with the other end of low-voltage side resistance and ground, and the base of switch tube receives switch control signal.The above technical scheme has the following effects:

[0048] 1. through the cooperation of first capacitor and tuning circuit unit in harmonic filter, especially the low impedance loop corresponding to distribution network harmonic formed by tuning circuit unit, harmonic current can be effectively guided to flow into filter, greatly reduce the adverse effects of harmonic generated by bidirectional full-bridge converter in working process on full-bridge component and distribution network, improve power quality;

[0049] 2. the integrated design of harmonic filter reduces the interference of harmonic to main circuit, reduces electromagnetic interference and voltage fluctuation in system, enhances the stability of entire system, reduces the risk of equipment failure;

[0050] 3. it can be adjusted and optimized according to different application scenarios and distribution network requirements, adapt to different harmonic characteristics and power quality requirements, and has wide application prospect in new energy, smart grid and industrial field etc.

[0051] It should be understood that the above specific embodiments of the present application are only used for illustrative or explanatory purposes of the principles of the present application, and do not constitute a limitation on the present application. Therefore, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present application shall be included in the protection scope of the present application. In addition, the appended claims of the present application are intended to cover all changes and modifications falling within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. A harmonic filter, characterized by Comprising: a first capacitor and a tuning loop unit connected in parallel; the tuning loop unit comprises a second capacitor, an autotransformer, a switching tube and a low-voltage side resistor; the second capacitor is connected in series with the high-voltage side of the autotransformer and then connected in parallel with the first capacitor; the collector of the switching tube is connected to one end of the low-voltage side of the autotransformer, one end of the low-voltage side resistor is connected to the other end of the low-voltage side of the autotransformer, the emitter of the switching tube is connected to the other end of the low-voltage side resistor and grounded, and the base of the switching tube receives a switching control signal.

2. The harmonic filter of claim 1, wherein, Further comprising: a lightning arrester; the lightning arrester is connected in parallel with the first capacitor.

3. The harmonic filter of claim 1, wherein: the magnitude of the reactance of the output end of the switching tube is related to the duty cycle of the control signal received by the base of the switching tube.

4. The harmonic filter of claim 1, wherein: the types of the first capacitor include aluminum electrolytic capacitor, tantalum capacitor, polymer capacitor and thin film capacitor.

5. The harmonic filter of claim 1, wherein: the types of the second capacitor include variable capacitor, voltage variable capacitor, ceramic capacitor, thin film capacitor, super capacitor, trimmer capacitor, MEMS capacitor and mica capacitor.

6. The harmonic filter of any one of claims 1-5, wherein: the tuning loop unit is a low-impedance loop corresponding to the harmonics of the power distribution network.

7. A bidirectional full-bridge converter, characterized by Comprising: a full-bridge assembly further comprising the harmonic filter of any one of claims 1-6; one end of the harmonic filter is connected to the midpoint of one half-bridge arm of the full-bridge assembly, and the other end is connected to the midpoint of the other half-bridge arm of the full-bridge assembly.

8. A new energy station harmonic control device, characterized in that, Comprising a plurality of bidirectional full-bridge converters as claimed in claim 7; the energy storage device and the three-phase connection mode of the new energy station power distribution network are Y-shaped, and the number of bidirectional full-bridge converters in each phase is the same and is a preset number.

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