Dynamic filtering compensation system and low-voltage power distribution system

Abstract

The embodiment of the utility model provides a dynamic filtering compensation system and a low-voltage power distribution system, and the system comprises a passive filtering unit which is connected with the low-voltage power distribution system and is configured to output a first filtering current according to the harmonic wave of the first frequency of the low-voltage power distribution system; the monitoring unit is connected with the low-voltage power distribution system and is configured to output a compensation control signal for compensating the low-voltage power distribution system according to the electrical information of the low-voltage power distribution system; and the active filtering unit is connected with the monitoring unit and the low-voltage power distribution system and is configured to output compensation current to the low-voltage power distribution system according to the compensation control signal. Harmonic waves with specific frequencies can be basically filtered out through the passive filtering unit, the active filtering unit dynamically generates compensation current according to control signals of the monitoring unit, rapid and accurate compensation is carried out on the harmonic waves and reactive power, the problems that passive filtering is slow in response and inaccurate in control are solved, and parallel resonance can be effectively avoided.

Description

Technical Field

[0001] The present disclosure relates to the field of power electronics technology, and in particular, to a dynamic filtering compensation system and a low-voltage distribution system. Background Art

[0002] With the continuous progress and popularization of power electronics technology, the increase of nonlinear loads and unbalanced loads in the power grid has brought unprecedented challenges to power quality. While these devices improve energy utilization efficiency and promote the development of new technologies, they also generate a large amount of harmonic current and harmonic voltage, as well as cause problems such as voltage fluctuation and flicker, seriously affecting the stability of the power grid and power quality, and further affecting the normal operation and lifespan of sensitive devices, increasing the maintenance cost.

[0003] In the compensation means in the related art, such as the combination of a static var generator (SVG) and an active power filter (APF), although it can effectively address the above problems, they usually need to be installed independently, not only with high initial investment costs, but also occupying a large space, which is particularly inconvenient for places with limited space. In addition, the static var generator SVG is mainly responsible for dynamic reactive power compensation, while the APF focuses on harmonic suppression. Although the combination of the two is comprehensive in function, it has deficiencies in terms of system integration, operation and maintenance convenience, and economy.

[0004] On the other hand, traditional LC filters (i.e., passive filters) and capacitor cabinets, although simple in structure and low in cost, have a slow response speed and are difficult to adapt to rapidly changing harmonic currents and reactive power demands. The LC filter may also resonate in parallel with the power grid, resulting in overvoltage or overcurrent phenomena, and even generating oscillations when the filter is switched, threatening the safe and stable operation of the system. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present disclosure is to provide a dynamic filtering compensation system and a low-voltage distribution system to solve the problems in the related art.

[0006] The first aspect of the present disclosure provides a dynamic filtering compensation system, which is applied to a low-voltage distribution system and includes:

[0007] A passive filtering unit, connected to the low-voltage distribution system, for filtering harmonics of a first frequency in the low-voltage distribution system;

[0008] A monitoring unit, connected to the low-voltage distribution system, configured to output a compensation control signal for compensating the low-voltage distribution system according to the electrical information of the low-voltage distribution system;

[0009] The active filtering unit is respectively connected to the monitoring unit and the low-voltage power distribution system, and generates a compensation current for compensating the low-voltage power distribution system in response to the compensation control signal.

[0010] In an embodiment of the first aspect, the passive filtering unit includes a plurality of passive components and at least one filtering circuit composed of the plurality of passive components for filtering out harmonics of the first frequency.

[0011] In an embodiment of the first aspect, the plurality of passive components include inductors and capacitors.

[0012] In an embodiment of the first aspect, the monitoring unit includes:

[0013] A detection module, connected to the low-voltage power distribution system, for monitoring electrical information of the low-voltage power distribution system;

[0014] A control module, respectively connected to the detection module and the active filtering unit, configured to obtain a first compensation control signal for controlling the active filtering unit to compensate for the reactive current of the low-voltage power distribution system according to the electrical information, and obtain harmonic current component information according to the electrical information to obtain a second compensation control signal for controlling the active filtering unit to filter out harmonics in a second frequency range of the low-voltage power distribution system.

[0015] In an embodiment of the first aspect, the second frequency range does not include the first frequency.

[0016] In an embodiment of the first aspect, the active filtering unit includes a reactive power generator, which outputs a current phase in response to the first compensation control signal in the compensation control signal to output a compensation current for reactive power regulation in the range from an inductive load to a capacitive load.

[0017] In an embodiment of the first aspect, the active filtering unit further includes an active power filter, which generates a compensation current with the same magnitude and opposite direction as the harmonic assignment of the second frequency of the low-voltage power distribution system in response to the second compensation control signal in the compensation control signal.

[0018] In an embodiment of the first aspect, the electrical information includes one or more of the current parameters and voltage parameters of the low-voltage power distribution system.

[0019] In an embodiment of the first aspect, it further includes: a power supply unit, respectively connected to the monitoring unit and the active filtering unit, for supplying power to the monitoring unit and the active filtering unit.

[0020] In a second aspect of the present disclosure, a low-voltage power distribution system is provided, in which harmonic filtering and reactive power compensation are performed by the dynamic filtering compensation system according to any of the above embodiments.

[0021] Advantages of the present disclosure: The passive filtering unit can basically filter out harmonics of specific frequencies, and the active filtering unit dynamically generates a compensation current according to the control signal of the monitoring unit to quickly and accurately compensate for harmonics and reactive power. This not only solves the problems of slow response and inaccurate control of traditional passive filtering, but also effectively avoids parallel resonance, improving the stability of the system and the power quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the modules of a dynamic filtering and compensation system according to an embodiment of the present disclosure is shown.

[0023] Figure 2 A schematic diagram of the modules of a dynamic filtering and compensation system according to another embodiment of the present disclosure is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following specific examples illustrate the embodiments of the present disclosure. Those skilled in the art can easily understand the other advantages and effects of the present disclosure from the information disclosed in the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments. Various details in the present disclosure can also be modified or changed according to different viewpoints and application scenarios without departing from the spirit of the present disclosure. It should be noted that, without conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0025] The following is a detailed description of the embodiments of the present disclosure with reference to the drawings, so that those skilled in the art to which the present disclosure pertains can easily implement it. The present disclosure can be embodied in many different forms and is not limited to the embodiments described herein.

[0026] In the description of the present disclosure, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present disclosure. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or a group of embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in the present disclosure and the features of different embodiments or examples.

[0027] In addition, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the representations of the present disclosure, the meaning of "a group" is two or more, unless otherwise specifically defined.

[0028] To clearly illustrate the present disclosure, devices irrelevant to the description are omitted, and the same or similar components throughout the specification are given the same reference signs.

[0029] Throughout the specification, when it is said that a device is "connected" to another device, this includes not only the case of "direct connection" but also the case of "indirect connection" with other elements interposed therebetween. Additionally, when it is said that a certain device "includes" a certain component, unless there is a particularly contrary record, it does not exclude other components but means that other components may also be included.

[0030] Although in some examples the terms first, second, etc. are used herein to denote various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first interface and the second interface, etc. are indicated. Furthermore, as used herein, the singular forms "a", "an", and "the" are also intended to include the plural forms unless the context indicates otherwise. It should be further understood that the terms "comprising", "including" indicate the presence of the stated features, steps, operations, elements, modules, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or a group of other features, steps, operations, elements, modules, items, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or meaning any one or any combination. Thus, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C". An exception to this definition occurs only when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0031] The technical terms used herein are only for referring to specific embodiments and are not intended to limit the present disclosure. The singular forms used herein also include the plural forms as long as the statements do not clearly indicate the contrary meaning. The meaning of "including" used in the specification is to embody specific characteristics, regions, integers, steps, operations, elements, and / or components, and does not exclude the existence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0032] Although not defined differently, including technical terms and scientific terms used herein, all terms have the same meaning as generally understood by those skilled in the technical field to which this disclosure belongs. Terms defined in commonly used dictionaries are additionally interpreted to have meanings consistent with relevant technical literature and the currently presented message. As long as they are not defined, they shall not be over-interpreted as ideal or overly formulaic meanings.

[0033] In the related art, most common filtering and compensation techniques for low-voltage power distribution systems 100 rely on passive filters with fixed parameters or active filters operating independently. Although passive filters have a simple structure and low cost, their filtering effect is greatly affected by changes in system parameters, making it difficult to achieve dynamic adaptation to harmonic suppression at different frequencies and prone to resonance with the system. Conventional active filters, although capable of dynamic response and precise compensation of specific harmonics, are often costly and require complex control systems to ensure stability. In addition, when the two are applied independently, there is a lack of comprehensive coordinated control at the system level, making it difficult to achieve the optimal power quality improvement effect.

[0034] This disclosure can basically filter out harmonics of specific frequencies through the passive filtering unit, while the active filtering unit dynamically generates compensation current according to the control signal of the monitoring unit to quickly and accurately compensate for harmonics and reactive power, not only solving the problems of slow response and inaccurate control of traditional passive filtering, but also effectively avoiding parallel resonance and improving the stability and power quality of the system.

[0035] In Figure 1 an example, a dynamic filtering and compensation system is provided, which is applied to the low-voltage power distribution system 100 and includes:

[0036] A passive filtering unit 200, connected to the low-voltage power distribution system 100, for filtering out harmonics of a first frequency in the low-voltage power distribution system 100;

[0037] Optionally, the passive filtering unit 200 includes a plurality of passive components and at least one filtering circuit composed of the plurality of passive components, and the at least one filtering circuit filters out the harmonics.

[0038] Specifically, in some embodiments, the passive filtering technique mainly relies on the combination of passive components (passive elements such as inductors L and capacitors C) to filter out harmonics of a specific frequency (the first frequency). A specific filter circuit is formed by the passive components, which is used to selectively allow or block signals within a specific frequency range, thereby reducing the impact of these harmonics on the power grid. Passive filters are usually designed for fixed or limited ranges of harmonic frequencies. Passive filtering is mainly used to suppress harmonic currents and voltages in the circuit and improve power quality. Passive components do not require an external power source or signal amplification, but rely on their own physical characteristics to change the frequency response of the signal. Therefore, in this example, the harmonics of the first frequency are filtered out by the passive filtering unit 200.

[0039] Optionally, the plurality of passive components include inductors and capacitors.

[0040] Specifically, the passive filtering technique is based on the combination of passive components - resistors (R), inductors (L), and capacitors (C), without involving active devices (such as transistors, operational amplifiers, etc.), so it is called "passive".

[0041] Optionally, in Figure 1 the example, the monitoring unit 300, connected to the low-voltage power distribution system 100, is configured to output a compensation control signal for compensating the low-voltage power distribution system 100 according to the electrical information of the low-voltage power distribution system 100;

[0042] Specifically, in some examples, the monitoring unit 300 monitors electrical parameters such as current, voltage, power factor, and harmonic content of the low-voltage power distribution system 100 in real time through sensors. These sensors can ensure the accuracy and real-time nature of the data. The collected electrical information is sent to the processor inside the monitoring unit 300, and digital signal processing techniques (such as the fast Fourier transform FFT) are used to analyze the harmonic components and calculate the reactive power demand. Based on the analysis results, the monitoring unit 300 calculates a compensation strategy, which includes determining the harmonic frequencies, amplitudes, and the magnitude and direction of the reactive power to be compensated, thereby generating a compensation control signal.

[0043] Optionally, in Figure 2 the example, the monitoring unit 300 includes:

[0044] A detection module 310, connected to the low-voltage power distribution system 100, for monitoring the electrical information of the low-voltage power distribution system 100.

[0045] Specifically, in some examples, the detection module 310 includes but is not limited to current sensors, voltage sensors, power factor sensors, etc. These sensors are responsible for capturing real-time electrical parameters such as line voltage, line current, phase voltage, phase current, active power, reactive power, and harmonic content.

[0046] Optionally, the electrical information includes at least one or more of the current parameters and voltage parameters of the low-voltage power distribution system 100.

[0047] In Figure 2 the example, the control module 320, which is respectively connected to the detection module 310 and the active filtering unit 400, is configured to obtain a first compensation control signal for compensating the reactive current of the low-voltage power distribution system 100 according to the electrical information, and obtain harmonic current component information according to the electrical information, so as to obtain a second compensation control signal for filtering the harmonics in the second frequency range of the low-voltage power distribution system 100.

[0048] Specifically, in some examples, based on the acquired electrical information, the control module 320 analyzes the current reactive current of the system through a built-in algorithm to obtain a reactive current compensation value, and generates a first compensation control signal. The control module 320 identifies the specific harmonic frequencies and amplitudes according to the harmonic current components in the electrical information. According to the analysis results, it calculates the compensation requirements for the harmonic currents in the second frequency range to be filtered, generates a second compensation control signal, and the active filtering unit 400 generates a current with an amplitude equal to and a phase opposite to that of the harmonic current in the system according to the second compensation control signal, so as to effectively filter out these harmful harmonics, improve the power quality, and protect the sensitive equipment in the system.

[0049] Optionally, in Figure 1 the example, the active filtering unit 400, which is respectively connected to the monitoring unit 300 and the low-voltage power distribution system 100, generates a compensation current for compensating the low-voltage power distribution system 100 in response to the compensation control signal.

[0050] Specifically, in some embodiments, the active filtering unit 400 realizes dynamic compensation for harmonics through the compensation current according to the current and voltage in the power grid. The active filter can not only handle harmonics of specific frequencies, but also adapt to the dynamic changes of the harmonic spectrum. The active filter has high flexibility and adaptability, can adjust the compensation strategy in real time, and effectively cope with the harmonic problems changing within a wide frequency band.

[0051] The passive filtering unit 200 generally has a simple structure, low cost, and good filtering effect on harmonics of specific frequencies. However, it has the disadvantages of fixed filtering characteristics and being easily affected by changes in system parameters. The active filtering unit 400 can dynamically respond to grid changes and accurately compensate for harmonics of any frequency, but the cost is relatively high. Combining the two can achieve harmonic suppression in a wider frequency spectrum while ensuring cost-effectiveness. The active filtering unit 400 is used to quickly respond to the changing harmonic components in the power grid and provide a highly dynamic compensation ability, while the passive filtering unit 200 can be used as a basic filtering layer to filter out some main or known harmonic frequencies. This not only ensures effective suppression of rapid harmonic changes but also ensures good filtering of constant or periodic harmonics. Compared with relying solely on a large-capacity passive filtering unit 200, the combination of the passive filtering unit 200 and the active filtering unit 400 can reduce the size and weight of the passive part, especially in situations where wide-spectrum harmonics need to be processed.

[0052] Optionally, in Figure 2 the example, the active filtering unit 400 includes a reactive power generator 410 that outputs a current phase in response to the first compensation control signal in the compensation control signal to output a compensation current for reactive power regulation in the range from an inductive load to a capacitive load.

[0053] Specifically, in some embodiments, the reactive power generator 410 (usually referred to as SVG, i.e., Static Var Generator) is a device based on power electronics technology used to dynamically provide or absorb reactive power to achieve rapid regulation of reactive power compensation in the power system. The reactive power generator 410 compensates for reactive current based on the first compensation control signal using a voltage source inverter (VSI) of power electronic devices such as IGBTs (Insulated Gate Bipolar Transistors). These devices can switch at high speeds, thus accurately controlling the amplitude and phase of the output current, i.e., the compensation current, and can generate a current with a phase opposite to that of the harmonic current in the low-voltage distribution system 100 to achieve active cancellation of harmonics and can also provide or absorb reactive current.

[0054] In the present disclosure, according to the instructions of the compensation control signal, the reactive power generator 410 can achieve continuous and smooth regulation from outputting inductive reactive power (equivalent to providing inductance-like compensation to support voltage) to capacitive reactive power (similar to the effect of a capacitor to absorb excess reactive power). This means that whether the power grid is in an over-compensation state (excessive reactive power causes voltage to rise) or an under-compensation state (insufficient reactive power causes voltage to drop), the system can accurately regulate to maintain the stability of the system voltage and optimize the power factor.

[0055] Optionally, in Figure 2In the example, the active filtering unit 400 further includes an active power filter 420, which responds to the second compensation control signal in the compensation control signal to generate a compensation current that is equal in magnitude and opposite in direction to the harmonic assignment of the second frequency of the low-voltage power distribution system 100.

[0056] Specifically, in some embodiments, the active power filter 420 (APF) is a device that can actively generate a compensation current that is equal in magnitude and opposite in direction to the harmonic current in the power grid, thereby eliminating harmonic pollution in the power system in real time. This compensation is based on the detected power grid current signal and analyzes the harmonic components therein through complex algorithms.

[0057] In this example, based on the results of real-time monitoring and analysis of the power grid current or voltage harmonics, the specific harmonic components that need to be compensated are quantified, and then an accurate compensation command value, that is, the second compensation control signal, is calculated.

[0058] The compensation current generated by the active power filter 420 according to the second compensation control signal is equal in magnitude to the harmonic assignment and opposite in direction, ensuring that the two cancel each other out when they meet in the system. Such a design not only improves the power quality, reduces the losses and failures of equipment caused by harmonics, but also enhances the stability and efficiency of the entire power grid.

[0059] The active power filter 420 is mainly used for dynamically suppressing and compensating harmonic currents in the power system, and can also perform active reactive power compensation. It can quickly track and compensate harmonics of different magnitudes and frequencies, improving the harmonic pollution problem of the power grid. It requires an external power supply to drive its active components (such as amplifiers). The static var generator 410 is mainly used for dynamic reactive power compensation, that is, improving the power factor of the power system to ensure the stability of the system voltage. It can quickly respond to changes in the reactive power demand of the system and effectively support the power grid voltage. The static var generator 410 is responsible for reactive power compensation and improving the power factor, while the active power filter 420 is used for filtering harmonic currents. The two work together to significantly improve the power quality of the power grid.

[0060] Optionally, in Figure 2 the example, the dynamic filtering compensation system further includes: a power supply unit, which is respectively connected to the monitoring unit 300 and the active filtering unit 400, and is used to supply power to the monitoring unit 300 and the active filtering unit 400.

[0061] Specifically, in some examples, the power supply unit can dynamically adjust the power supply strategy for each unit according to the system status fed back by the monitoring unit 300 and the actual power consumption demand of the active filter unit 400 to achieve the optimal configuration of energy, and the active power filter 420 needs to be driven by an external power supply. The active filter unit 400 needs to respond quickly to the instructions of the monitoring unit 300 when working, and perform high-frequency switching operations, which has high requirements for power quality. The power supply unit not only provides electrical energy, but also needs to ensure the stable output of voltage and current to avoid the precise control of the active filter due to power fluctuations, thereby ensuring the stability of the entire system and the improvement of power quality.

[0062] Optionally, the second frequency range does not include the first frequency.

[0063] Specifically, in some examples, the first frequency is used by the passive filtering unit 200 to filter out specific harmonic frequencies in the power grid, and filters out specific harmonic frequencies appearing in the power grid, such as the 5th and 7th harmonics. Due to its physical characteristics based on fixed elements, the filtering range of the passive filter is relatively fixed and has limited adaptability. The second frequency range generally covers a wider range of harmonic frequencies, including but not limited to those frequencies that are not processed by the passive filter, thereby providing a more comprehensive harmonic control capability.

[0064] In some examples, the division of labor and complementarity between the active filter unit 400 and the passive filter unit 200 in frequency compensation, that is, the active filter unit 400 is used to process harmonic frequencies that are not within the processing range of the passive filter unit 200, ensuring that the entire system can more comprehensively cope with various harmonic pollution and improve power quality. Such a design idea is conducive to optimizing system performance, avoiding resource waste, and ensuring efficient and precise control of harmonic governance in the power grid.

[0065] In yet another embodiment of the present disclosure, a low-voltage power distribution system is provided, wherein harmonic filtering and reactive power compensation are performed by a dynamic filtering and compensation system of any of the above embodiments.

[0066] The above embodiments are merely illustrative of the principles and effects of the present disclosure, and are not intended to limit the present disclosure. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present disclosure. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed in the present disclosure shall still be covered by the protection scope of the present disclosure.

Claims

1. A dynamic filtering compensation system, characterized in that: Applicable to low voltage power distribution system; including: A passive filtering unit, connected to the low-voltage power distribution system, for filtering out harmonics of a first frequency in the low-voltage power distribution system; A monitoring unit connected to the low-voltage power distribution system and configured to output a compensation control signal for compensating the low-voltage power distribution system according to electrical information of the low-voltage power distribution system; The active filtering unit is respectively connected to the monitoring unit and the low-voltage power distribution system, and generates a compensation current for compensating the low-voltage power distribution system in response to the compensation control signal.

2. The dynamic filtering compensation system according to claim 1, characterized in that: The passive filtering unit includes a plurality of passive components and at least one filtering circuit composed of the plurality of passive components, and is used to filter out harmonics of the first frequency.

3. The dynamic filtering compensation system according to claim 2, characterized in that: The passive components include inductors and capacitors.

4. The dynamic filtering compensation system according to claim 1, characterized in that: The monitoring unit comprises: A detection module, connected to the low-voltage power distribution system, for monitoring electrical information of the low-voltage power distribution system; The control module is respectively connected to the detection module and the active filtering unit, and is configured to obtain a first compensation control signal for controlling the active filtering unit to compensate for the reactive current of the low-voltage power distribution system according to the electrical information, and to obtain harmonic current component information according to the electrical information to obtain a second compensation control signal for controlling the active filtering unit to filter out harmonics in a second frequency range of the low-voltage power distribution system.

5. The dynamic filtering compensation system according to claim 4, characterized in that: The second frequency range does not include the first frequency.

6. The dynamic filtering compensation system according to claim 1, characterized in that: The active filtering unit includes a reactive power generator, which outputs a current phase in response to a first compensation control signal among the compensation control signals, so as to output a compensation current for performing reactive power regulation on a range from an inductive load to a capacitive load.

7. The dynamic filtering compensation system according to claim 1, characterized in that: The active filtering unit further includes an active power filter, which responds to a second compensation control signal in the compensation control signal to generate a compensation current having the same harmonic value and opposite direction as the harmonic assignment of the second frequency of the low-voltage power distribution system.

8. The dynamic filtering compensation system according to claim 1, characterized in that: The electrical information includes one or more of current parameters and voltage parameters of the low-voltage power distribution system.

9. The dynamic filtering compensation system according to claim 1, characterized in that: Also includes: A power supply unit is respectively connected to the monitoring unit and the active filtering unit, and is used to supply power to the monitoring unit and the active filtering unit.

10. A low voltage power distribution system, characterized in that: Harmonic filtering and reactive power compensation are performed by a dynamic filtering and compensation system as described in any one of claims 1 to 9.

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