A power quality treatment device for a power distribution network of a photovoltaic power station

Abstract

This invention relates to the field of power distribution network management technology and discloses a power quality management device for photovoltaic power station power distribution networks. The device includes a housing and a first current sharing plate and a second current sharing plate inserted inside. The first current sharing plate is equipped with a high-frequency isolation converter, and the second current sharing plate is equipped with a mounting frame. A harmonic processing module and a multi-terminal energy router are sequentially mounted on the mounting frame. A DC connection port electrically connected to the multi-terminal energy router is installed on the side wall of the housing. The harmonic processing module includes a circuit breaker connected in parallel to the power grid bus, an LCL filter bank, a shared IGBT three-phase bridge, and a multi-function controller. The multi-function controller integrates a harmonic extraction algorithm module, a reactive power / voltage droop control module, and a mode switching logic module. This device simultaneously achieves comprehensive management of harmonic suppression, reactive power compensation, and voltage regulation, and supports plug-and-play and multi-terminal energy management for DC source loads such as energy storage and photovoltaics. It features a compact structure and high power density.

Description

Technical Field

[0001] This invention relates to the field of power distribution network management technology, and in particular to a device for improving the power quality of a photovoltaic power plant power distribution network. Background Technology

[0002] In photovoltaic power plant distribution networks, with the continuous expansion of distributed photovoltaic grid connection, power quality issues in the distribution network have received increasing attention. Currently, various power quality management devices have been deployed to address common problems in distribution networks such as voltage fluctuations, harmonic pollution, low power factor, and three-phase imbalance. These devices mainly include active power filters (APF), static var generators (SVG), and dynamic voltage restorers (DVR), used for harmonic suppression, reactive power compensation, and voltage regulation, respectively. Regarding voltage isolation and regulation, existing devices mostly use power frequency transformers to achieve voltage compensation and electrical isolation. For DC-side connection, some devices are beginning to be equipped with DC ports for connecting photovoltaic, energy storage, and other DC equipment, and power coordination is achieved through energy management modules. In terms of device structure, an integrated chassis is typically used, with each functional unit installed internally via fixed brackets.

[0003] The aforementioned and existing related technologies have the following drawbacks: harmonic suppression, reactive power compensation, and voltage regulation functions are separate, making it impossible to simultaneously address these three power quality issues within a single device; the use of power frequency transformers results in large device size and low power density, making it difficult to meet the development needs of distribution networks for compact and lightweight equipment; and the lack of DC connection ports and multi-terminal energy routers prevents the "plug-and-play" functionality of DC power sources such as energy storage and photovoltaics, and also lacks multi-terminal energy management and coordinated control capabilities. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that the existing technology has the disadvantages of harmonic suppression, reactive power compensation and voltage regulation functions being separate and unable to be integrated, the use of power frequency transformers resulting in large size and low power density, and the lack of DC connection ports and multi-terminal energy routers, which makes it impossible to achieve plug-and-play DC source load and multi-terminal energy management and coordinated control. To this end, we propose a power quality management device for photovoltaic power station distribution network.

[0005] To achieve the above objectives, this application adopts the following technical solution: a power quality management device for photovoltaic power station distribution network, comprising a box and a terminal block fixedly connected to the top of the box. A slot is provided in the inner wall of the box, and a first current equalization plate and a second current equalization plate are movably inserted into the slot in sequence. A high-frequency isolation converter is fixedly connected to the top of the first current equalization plate, and a mounting frame is fixedly connected to the top of the second current equalization plate. A harmonic processing module and a multi-terminal energy router are sequentially arranged on the top of the mounting frame. A DC connection port is fixedly installed on the outer wall of one side of the box, and the multi-terminal energy router is electrically connected to the DC connection port through a wire. The harmonic processing module includes: Circuit breakers connected in parallel to the power grid busbar; An LCL filter bank connected to the output of the circuit breaker; a shared IGBT three-phase bridge with a DC bus capacitor and energy storage unit connected to the inverter side of the LCL filter bank on the AC side and the inverter side of the LCL filter bank on the DC side. And a multi-functional controller that is connected to the PCC, DC bus capacitor and IGBT three-phase bridge signal respectively; The multi-functional controller integrates a harmonic extraction algorithm module, a reactive power / voltage droop control module, and a mode switching logic module. It is used to control the output of the shared IGBT three-phase bridge to provide corresponding compensation current based on the detected electrical quantities of the power grid, so as to simultaneously perform harmonic suppression, reactive power compensation, and voltage regulation.

[0006] Preferably, hollow fins are fixedly connected to the side walls and doors of the box at even intervals. The inner cavity of the hollow fins is connected to the box. Reinforcing rods are fixedly connected to the upper and lower side walls of the hollow fins on each side of the box. The reinforcing rods are located at the ends of the hollow fins away from the box.

[0007] Preferably, an inner groove is provided between the hollow fins on the outer side of the DC connection port, the DC connection port is fixedly connected to the side wall of the box between the inner grooves, and the end of the DC connection port is housed in the inner groove port.

[0008] Preferably, the bottom plate of the box is integrally formed with an installation cylinder, the inner wall of the installation cylinder is fixedly connected with a fixing bracket, the end of the fixing bracket is fixed with a cooling fan, and the top of the box is sequentially fixed with interconnected exhaust valve pipes.

[0009] Preferably, the exhaust valve pipe includes a U-shaped cylinder fixedly connected to and communicating with the top of the housing. The lower end of the U-shaped cylinder extends into the interior of the housing. An isolation cover with an air hole at the lower end is fixedly connected to the outer wall of the top port of the U-shaped cylinder. A rotating shaft is rotatably connected to the lower end of the top plate of the isolation cover. The lower end of the rotating shaft extends into the U-shaped cylinder. A fixed plate is fixedly connected to the outer wall of the rotating shaft inside the isolation cover. Sealing arc plates are movably connected at even intervals at the lower edge of the fixed plate. After the sealing arc plates are put together, they form a frustum-shaped sealing cover. A vortex fan is fixedly connected to the bottom of the rotating shaft.

[0010] Preferably, a rubber ring is fixedly connected to the outer wall of the rotating shaft at the lower end of the sealing arc plate, a movable ring is movably sleeved on the outer wall of the rotating shaft of the rubber ring, a return spring is fixedly connected between the rubber ring and the movable ring, and a connecting strip is fixedly connected to the top edge of the movable ring corresponding to the sealing arc plate, and the top end of the connecting strip moves through the rubber ring and is fixedly connected to the inner wall at the lower end of the sealing arc plate.

[0011] Preferably, the top of the rubber ring is flush with the top port of the convex-shaped cylinder. When the return spring is in a normally relaxed state, the lower sidewalls of the sealing arc plate are in contact with each other, and the lower end of the sealing arc plate is tightly in contact with the outer wall of the top of the convex-shaped cylinder port.

[0012] Preferably, a boss is fixedly connected to one end of the top of the mounting bracket, and the multi-terminal energy router is fixedly connected to the upper end of the boss. Slotted holes are opened on both sides of the top of the mounting bracket outside the boss, and locking parts are provided in the slotted holes. The bottom sides of the harmonic processing module housing are provided with grooved hooks corresponding to the locking parts.

[0013] Preferably, the locking component is used to detachably fix the harmonic processing module, and the mounting bracket between the locking components has protrusions fixedly connected to the top two sides respectively, and the bottom two sides of the harmonic processing module housing are provided with limit holes corresponding to the protrusions.

[0014] Preferably, the locking component includes deflector seats rotatably connected between the inner walls of the two ends of the two slots. One of the slots has through holes on the side walls of the deflector seats at both ends. A deflector rod is movably connected between the inner walls of the through holes. A slider is fixedly connected to the end of the deflector rod. The slider is movably engaged in the slot. A limit rod is fixedly connected between the side walls of the deflector seats. The limit rod is perpendicular to the slot and is set corresponding to the hook portion. A portal frame is fixedly connected to the top of the mounting bracket above the slider. The portal frame is suspended across the slot. A screw is rotatably connected to the top of the portal frame. The lower end of the screw is threaded into the inside of the slider.

[0015] The technical effects and advantages of this invention are as follows: In this invention, by integrating a high-frequency isolation converter, a harmonic processing module, and a multi-terminal energy router into a single enclosure, and utilizing a first current sharing board and a second current sharing board for modular connection, the problem of separate and difficult-to-integrate harmonic suppression, reactive power compensation, and voltage regulation functions in existing technologies is effectively solved. The harmonic processing module uses a shared IGBT three-phase bridge and a multi-functional controller, internally integrating harmonic extraction algorithms, reactive power / voltage droop control, and mode switching logic. It can dynamically output compensation current based on the grid's electrical quantities, simultaneously achieving harmonic filtering, continuous reactive power regulation, and voltage regulation. Voltage stability control avoids the complex wiring and coordination difficulties of parallel connection of multiple discrete devices; high-frequency isolation converters replace traditional power frequency transformers, significantly reducing device size and weight and increasing power density; at the same time, the setting of multi-terminal energy routers and DC connection ports enables DC power sources such as energy storage and photovoltaics to be plug-and-play, with multi-terminal energy management and coordination control capabilities, which can effectively smooth photovoltaic power fluctuations and enhance the distribution network's ability to accept distributed energy; a single parallel access method can complete the comprehensive management of various power quality problems in the distribution network, with a compact structure and high functional integration. Attached Figure Description

[0016] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts: Figure 1 This is a schematic diagram of the overall structure of a photovoltaic power station power distribution network power quality management device according to the present invention; Figure 2 This is a cross-sectional structural diagram of the housing of a photovoltaic power station power distribution network power quality management device according to the present invention; Figure 3 This is a diagram illustrating the harmonic processing module architecture of a photovoltaic power station power distribution network power quality management device according to the present invention. Figure 4 This is a schematic cross-sectional view of the exhaust valve pipe of a photovoltaic power station power distribution network power quality management device according to the present invention. Figure 1 ; Figure 5 This is a schematic cross-sectional view of the exhaust valve pipe of a photovoltaic power station power distribution network power quality management device according to the present invention. Figure 2 ; Figure 6 This is a schematic diagram of the mounting frame, harmonic processing module, and multi-terminal energy router of a photovoltaic power station power distribution network power quality management device according to the present invention. Figure 7 This invention relates to a power quality management device for photovoltaic power plant distribution networks. Figure 6 Enlarged structural diagram at point A in the middle; Figure 8 This is a schematic diagram of the mounting frame structure of a photovoltaic power station power distribution network power quality management device according to the present invention; Figure 9 This is a schematic diagram of the locking component structure of a photovoltaic power station power distribution network power quality management device according to the present invention.

[0017] In the diagram: 1. Housing; 11. Terminal block; 12. Mounting sleeve; 13. Fixing bracket; 14. Cooling fan; 15. Hollow fin plate; 151. Reinforcing rod; 152. Inner groove; 2. First current equalization plate; 3. Second current equalization plate; 4. High-frequency isolation converter; 5. Mounting bracket; 51. Boss; 52. Strip hole; 53. Locking element; 531. Deflection seat; 532. Through hole; 533. Deflection rod; 534. Slider; 5 35. Limiting rod; 536. Gantry frame; 537. Screw; 54. Protruding column; 6. Harmonic processing module; 61. Slot hook; 7. Multi-terminal energy router; 8. DC connection port; 9. Exhaust valve pipe; 91. T-shaped cylinder; 92. Isolation cover; 93. Rotating shaft; 931. Fixed plate; 932. Vortex fan; 94. Sealing arc plate; 95. Rubber ring; 96. Moving ring; 97. Return spring; 98. Connecting belt. Detailed Implementation

[0018] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0019] Reference Figures 1-3 As shown, the present invention provides a technical solution: a power quality management device for a photovoltaic power station distribution network, comprising a housing 1 and terminals 11 fixedly connected to the top of the housing 1. The terminals 11 are used for electrical connection with the external power grid. Multiple terminals 11 are provided, corresponding to each phase of the three-phase AC power, as well as the neutral line and the ground line. The housing 1 is made entirely of metal, possessing good electromagnetic shielding performance and mechanical strength. The preferred shape of the housing 1 is a cuboid structure, and its dimensions can be designed according to the actual power level and application scenario. The terminals 11 are fixedly installed on the top of the housing 1. The number and specifications of the terminals 11 are determined according to the capacity of the treatment device and the access voltage level. The inner wall of the enclosure 1 is provided with a slot (not shown in the figure). The first current equalizing plate 2 and the second current equalizing plate 3 are movably inserted into the slot in sequence. The first current equalizing plate 2 and the second current equalizing plate 3 are used to support and install the high-frequency isolation converter 4 and the mounting bracket 5, and at the same time play the role of electrical insulation and air conduction and heat dissipation. The current equalizing plates are made of insulating and thermally conductive materials, such as ceramic substrates or high thermal conductivity insulating composite materials. The first current equalizing plate 2 and the second current equalizing plate 3 can be pulled out from the slot for easy maintenance and replacement of internal components.

[0020] A high-frequency isolation converter 4 is fixedly connected to the top of the first current equalization plate 2. The high-frequency isolation converter 4 is used to realize high-frequency electrical isolation and energy conversion between the photovoltaic side and the grid side, improve energy conversion efficiency, and suppress common-mode interference. The high-frequency isolation converter 4 uses a high-frequency transformer as the isolation element. The switching frequency is usually between 20kHz and 100kHz, preferably 50kHz, which can significantly reduce the size and weight of the transformer. A mounting bracket 5 is fixedly connected to the top of the second current equalization plate 3. The mounting bracket 5 is used to support and fix the harmonic processing module 6 and the multi-terminal energy router 7. The mounting bracket 5 is made of metal profile and has sufficient strength and rigidity. The harmonic processing module 6 and the multi-terminal energy router 7 are arranged sequentially on the top of the mounting bracket 5. The harmonic processing module 6 is close to the inlet side of the box 1, and the multi-terminal energy router 7 is close to the DC connection port 8.

[0021] A DC connection port 8 is fixedly installed on one side of the outer wall of the enclosure 1. The DC connection port 8 is used to connect external DC equipment, such as photovoltaic modules or energy storage systems. The DC connection port 8 can use standard DC terminals or special connectors, and has anti-misinsertion and protection functions. The DC connection port 8 is equipped with two terminals, positive and negative, and is equipped with a protective cover.

[0022] The multi-terminal energy router 7 is electrically connected to the DC connection port 8 via a wire. The multi-terminal energy router 7 is used to coordinate the energy flow of multiple energy sources (such as photovoltaic, energy storage, and power grid) to achieve intelligent energy management. The multi-terminal energy router 7 has multiple energy ports and can simultaneously connect distributed energy devices such as photovoltaic arrays, energy storage batteries, and electric vehicle charging piles. It can also dynamically adjust the energy flow direction and power of each port according to grid dispatch instructions and local optimization strategies.

[0023] like Figure 3 As shown, the harmonic processing module 6 is used to simultaneously achieve harmonic suppression, reactive power compensation and voltage regulation. The harmonic processing module 6 includes a circuit breaker, an LCL filter bank, a shared IGBT three-phase bridge and a multi-function controller.

[0024] Circuit Breaker: The circuit breaker is connected in parallel to the power grid bus to isolate or connect the harmonic processing module 6 to the power grid. The circuit breaker adopts a vacuum circuit breaker or SF6 circuit breaker, which has good arc extinguishing capability and short circuit protection function. The rated current of the circuit breaker is selected according to the capacity of the treatment device, which is usually 1.2 to 1.5 times the rated current of the treatment device. The circuit breaker is also equipped with a manual operating mechanism and an electric operating mechanism, which can realize remote control and local control.

[0025] LCL Filter Bank: The LCL filter bank is connected to the output terminal of the circuit breaker and is used to filter out high-frequency harmonics generated by the IGBT three-phase bridge switch. The LCL filter bank adopts a third-order filter structure, including filter inductor L1, filter inductor L2 and filter capacitor C. Filter inductor L1 is connected between the output terminal of the circuit breaker and the IGBT three-phase bridge. Filter capacitor C is connected in parallel across the two ends of filter inductor L2. Filter inductor L2 is connected between filter capacitor C and PCC (common coupling point).

[0026] The LCL filter bank's parameter design must meet the following requirements: sufficient attenuation at the switching frequency (typically requiring attenuation of 60dB or more); low impedance at the fundamental frequency to avoid excessive fundamental power loss; and a sufficiently large total inductance (including L1 and L2) to limit ripple current. In a preferred embodiment, the LCL filter bank's parameters are optimized based on the capacity and switching frequency of the treatment device. For example, for a treatment device with a rated power of 500kVA and a switching frequency of 10kHz, L1 can be designed to be 0.5mH, L2 to be 0.2mH, and C to be 50μF.

[0027] Shared IGBT three-phase bridge: The AC side of the shared IGBT three-phase bridge is connected to the inverter side of the LCL filter bank (i.e., the node between L1 and L2), and the DC side is connected to the DC bus capacitor and optional energy storage unit. The shared IGBT three-phase bridge adopts a three-phase bridge inverter topology, consisting of six IGBT power devices and six anti-parallel diodes.

[0028] The working principle of the shared IGBT three-phase bridge is as follows: When the compensation current needs to be output, the IGBT power devices switch according to the PWM modulation strategy to convert the DC side voltage into the AC side voltage, which is then injected into the grid through the LCL filter bank. When the IGBT three-phase bridge is working in rectification mode, it can convert the grid AC power into DC power to charge the DC bus capacitor or store energy in the energy storage unit.

[0029] DC bus capacitors are used to support the DC-side voltage and reduce DC-side voltage ripple. The capacitance value of the DC bus capacitor is determined based on the DC-side voltage level and ripple requirements. A combination of electrolytic capacitors and film capacitors is typically used to balance capacitance and frequency characteristics.

[0030] Optional energy storage units are connected to both ends of the DC bus capacitor to store and release energy. The energy storage units can be lithium batteries, lead-acid batteries or supercapacitors. The introduction of energy storage units enables the governance device to cope with photovoltaic power fluctuations. It can discharge to the grid when photovoltaic output is insufficient and absorb excess energy when photovoltaic output is excessive.

[0031] Multifunctional Controller: The multifunctional controller is connected to the PCC, DC bus capacitor and IGBT three-phase bridge signal respectively, and is used to collect the electrical quantities of the power grid and DC side in real time, and control the IGBT three-phase bridge to output the corresponding compensation current.

[0032] The multi-functional controller integrates three main functional modules: Harmonic Extraction Algorithm Module: This module extracts harmonic components from the acquired power grid current signal. Various methods can be employed, including the IP-IQ algorithm based on instantaneous reactive power theory, the FFT algorithm based on Fourier transform, or an adaptive algorithm based on neural networks. The module can accurately detect harmonic currents ranging from the 2nd to the 50th harmonic order and calculate the corresponding compensation current reference values.

[0033] Reactive power / voltage droop control module: Used to achieve dynamic compensation of reactive power and voltage regulation. The reactive power / voltage droop control module adopts virtual synchronous generator technology to simulate the external characteristics of a synchronous generator, automatically adjusting the output reactive power according to the grid voltage deviation. When the grid voltage is lower than the set value, the control device outputs reactive power to the grid (equivalent to the capacitive operation mode of an SVG); when the grid voltage is higher than the set value, the control device absorbs reactive power from the grid (equivalent to the inductive operation mode of an SVG).

[0034] Mode switching logic module: Used to automatically switch operating modes based on power grid conditions and load demand. The mode switching logic module can implement the following operating modes: Harmonic compensation mode: mainly for harmonic compensation, suitable for situations with severe harmonic pollution.

[0035] Reactive power compensation mode: mainly performs reactive power compensation, suitable for situations with large voltage fluctuations.

[0036] 3. Hybrid compensation mode: Simultaneously performs harmonic suppression and reactive power compensation, suitable for comprehensive power quality management applications.

[0037] 4. Voltage Regulation Mode: Primarily used for voltage regulation, suitable for voltage support applications at the end of long lines.

[0038] 5. Energy storage charging and discharging mode: Utilizes energy storage units for energy storage and release, suitable for coordinating with photovoltaic power fluctuations.

[0039] The mode switching logic module automatically determines the current grid state based on collected grid electrical quantities (such as harmonic content, power factor, voltage deviation, etc.) and selects the optimal operating mode. During the switching process, a smooth transition strategy is adopted to avoid impacting the grid.

[0040] Connected in parallel to the grid connection point (PCC) of the photovoltaic power plant, the multi-functional controller monitors the voltage and current at the PCC in real time. Using a built-in harmonic extraction algorithm, it separates the load-side harmonic components and calculates the required reactive power compensation and voltage regulation based on the reactive power / voltage droop control module. According to the mode switching logic, the controller dynamically allocates the capacity of the shared IGBT three-phase bridge, ensuring its output provides a compensation current with equal amplitude and opposite phase to the grid harmonics to filter out harmonics. Simultaneously, it generates or absorbs continuously adjustable reactive power to maintain the power factor within the set range and suppresses voltage fluctuations by adjusting reactive power when voltage exceeds limits. The DC bus capacitor provides instantaneous energy buffering, and optional energy storage units can provide additional active power support during deep voltage sags. The entire device, with its software-defined operating mode, requires only a single parallel connection to achieve comprehensive power quality management.

[0041] To ensure the reliable operation of the treatment device under various environmental conditions, such as Figures 1-2 and Figures 4-5 As shown, hollow fins 15 are evenly spaced and fixedly connected to the side walls and doors of the housing 1. The inner cavity of the hollow fins 15 is connected to the internal space of the housing 1 to form an air convection channel. When there are many hollow fins, the radiative heat dissipation volume of the housing 1 is greatly increased. When the treatment device is running, the heat generated inside can be radiated to the outside air through the inner cavity of the hollow fins 15 to achieve rapid natural radiative heat dissipation. The hollow fins 15 are made of aluminum alloy by extrusion molding process, which has the advantages of light weight and good heat dissipation effect. The shape of the hollow fins 15 can be wavy, sawtooth or straight, and the specific shape is determined according to the heat dissipation requirements. The spacing of the hollow fins 15 is determined according to the size of the housing 1 and the heat dissipation requirements, preferably 20mm to 50mm.

[0042] To improve the structural strength of the hollow fins 15, reinforcing rods 151 are fixedly connected to the upper and lower side walls of each hollow fin 15 on the side of the housing 1. The reinforcing rods 151 are located at the ends of the hollow fins 15 furthest from the housing 1, and are used to enhance the bending resistance and overall stability of the hollow fins 15. The reinforcing rods 151 are made of the same material as the hollow fins 15 and are fixed by welding or screws. The numerous hollow fins 15 all have their sides pointing vertically outwards. When the housing 1 is subjected to a circumferential impact, the skeletal toughness of the hollow fins 15 prevents them from bending and deforming. Simultaneously, the mutual compression between adjacent hollow fins 15 effectively prevents serious damage to the equipment inside the housing 1 from external impacts, effectively protecting it and reducing losses.

[0043] An inner groove 152 is provided between the hollow fins 15 on the outside of the DC connection port 8. The DC connection port 8 is fixedly connected to the side wall of the housing 1 between the inner grooves 152, and the end of the DC connection port 8 is tucked into the port of the inner groove 152. This structure makes the DC connection port 8 hidden between the hollow fins 15, which is both aesthetically pleasing and prevents accidental contact. An installation cylinder 12 is integrally formed at the lower end of the bottom plate of the housing 1. The installation cylinder 12 is a cylindrical structure used to install a cooling fan. A fixing bracket 13 is fixedly connected to the inner wall of the installation cylinder 12. The cooling fan 14 is fixedly connected to the end of the fixing bracket 13. The cooling fan 14 is an axial flow fan or a centrifugal fan for forced cooling. When the power of the treatment device is high or the ambient temperature is high, the cooling fan 14 will start automatically to enhance the air circulation inside the housing 1 and improve the cooling effect.

[0044] An exhaust valve pipe 9 is fixedly connected to the top of the housing 1. The exhaust valve pipe 9 is used to exhaust hot air from inside the housing 1 and prevent external rainwater and dust from entering. The exhaust valve pipe 9 includes a U-shaped cylinder 91 fixedly connected to the top of the housing 1 and in communication with it. The U-shaped cylinder 91 is a U-shaped cylindrical structure, and its lower end extends into the interior of the housing 1 and communicates with the interior space of the housing 1. An isolation cover 92 with an air hole at the lower end is fixedly connected to the outer wall of the top port of the U-shaped cylinder 91. The isolation cover 92 is an inverted funnel-shaped structure, with a closed top and an open bottom. The air hole is opened on the bottom plate of the isolation cover 92, which is used for air intake and prevents rainwater from entering directly. A rotating shaft 93 is rotatably connected to the lower end of the top plate of the isolation cover 92. The rotating shaft 93 can rotate relative to the isolation cover 92, and its lower end extends into the U-shaped cylinder 91. A fixed disk 931 is fixedly connected to the outer wall of the shaft 93. The fixed disk 931 is a circular disk structure. Sealing arc plates 94 are evenly spaced and movably connected to its lower edge. The sealing arc plates 94 are arc-shaped plate structures. After multiple sealing arc plates 94 are put together, they form a frustum-shaped sealing cover, which is used to seal the top port of the convex cylinder 91. A vortex fan 932 is fixedly connected to the bottom of the shaft 93. When the vortex fan 932 is working, it generates an upward suction force, which drives the hot air inside the housing 1 to flow upward and be discharged through the convex cylinder 91 and the isolation cover 92. When the vortex fan 932 stops working, the sealing arc plates 94 fall down under the action of gravity and put together. At the same time, the lower end of the sealing arc plate 94 is tightly put into contact with the top outer wall of the port of the convex cylinder 91 to achieve automatic sealing, preventing water vapor and dust from entering the inside of the housing 1 and effectively protecting its internal electronic components.

[0045] To further improve the sealing performance of the exhaust valve pipe 9, a rubber ring 95 is fixedly connected to the outer wall of the rotating shaft 93 at the lower end of the sealing arc plate 94. A movable ring 96 is movably sleeved on the outer wall of the rotating shaft 93 of the rubber ring 95. The movable ring 96 can slide up and down on the rotating shaft 93, and its inner diameter is slightly larger than the outer diameter of the rotating shaft 93. A return spring 97 is fixedly connected between the rubber ring 95 and the movable ring 96. The return spring 97 is a compression spring, one end of which is fixedly connected to the rubber ring 95, and the other end is fixedly connected to the movable ring 96. A connecting strip 98 is fixedly connected to the top edge of the movable ring 96 at the corresponding position of the sealing arc plate 94. The connecting strip 98 is a flexible strip structure, and its top end moves through the rubber ring 95 and is fixedly connected to the inner wall at the lower end of the sealing arc plate 94.

[0046] The working principle of this structure is as follows: When the vortex fan 932 starts, it generates an upward airflow thrust, which drives the sealing arc plate 94 to deflect upward. At this time, the return spring 97 is compressed and the moving ring 96 slides upward, so that the connecting belt 98 is tightened. When the vortex fan 932 stops, the return spring 97 releases its elastic potential energy, which pushes the moving ring 96 to move downward. Through the connecting belt 98, the sealing arc plate 94 moves downward and fits together to achieve a seal.

[0047] The top of the rubber ring 95 is flush with the top port of the convex cylinder 91. When the return spring 97 is in a normally relaxed state, the lower side walls of the sealing arc plate 94 are in contact with each other, and the lower end of the sealing arc plate 94 is tightly attached to the top outer wall of the port of the convex cylinder 91. This structure can ensure that the exhaust valve pipe 9 is completely sealed when the vortex fan 932 stops working, preventing water vapor and dust from entering.

[0048] To facilitate the installation and maintenance of harmonic processing module 6, such as Figure 2 and Figures 6-9 As shown, a boss 51 is fixedly connected to one end of the top of the mounting bracket 5. The boss 51 is a cuboid structure, and its height matches the installation height of the harmonic processing module 6 and the multi-terminal energy router 7. The multi-terminal energy router 7 is fixedly connected to the upper end of the boss 51 by bolts or clips. The top two sides of the mounting bracket 5 on the outside of the boss 51 are respectively provided with strip holes 52. Locking parts 53 are provided in the strip holes 52 for detachable fixing of the harmonic processing module 6. The bottom two sides of the housing of the harmonic processing module 6 are provided with groove hook parts 61 corresponding to the locking parts 53. The groove hook parts 61 are hook-shaped structures that can cooperate with the locking parts 53 to realize the quick installation and removal of the harmonic processing module 6.

[0049] The specific structure of the locking component 53 is as follows: The locking component 53 includes deflector seats 531 that are rotatably connected between the inner walls of the two ends of the two slotted holes 52. The deflector seats 531 have an L-shaped structure and can rotate around the connection point with the inner wall of the slotted hole 52. One of the slotted holes 52 has through holes 532 on the side walls of the deflector seats 531 at both ends. The opening direction of the through holes 531 is parallel to the length direction of the slotted hole 52. A deflector rod 533 is movably connected between the inner walls of the through holes 532 and can deflect based on the shaft within the through holes 532. A slider 534 is fixedly connected to the end of the deflection rod 533. The slider 534 is a cuboid structure, and its width matches the strip hole 52. It can be movably engaged in the strip hole 52 and can slide along the vertical direction of the strip hole 52. A limit rod 535 is fixedly connected between the side walls of the deflection seat 531. The limit rod 535 is perpendicular to the strip hole 52 and is set corresponding to the slot hook part 61. When the harmonic processing module 6 is installed in place, the limit rod 535 is engaged in the slot hook part 61 to prevent the module from moving in the horizontal direction. A portal frame 536 is fixedly connected to the top of the mounting bracket 5 above the slider 534. The portal frame 536 is a portal frame structure that spans and is suspended above the strip hole 52. A screw 537 is rotatably connected to the top of the portal frame 536. The screw 537 can rotate relative to the portal frame 536, and its lower end is threaded into the inside of the slider 534.

[0050] On both sides of the top of the mounting bracket 5 between the locking components 53, protrusions 54 are fixedly connected. Limiting holes (not shown in the figure) are provided on both sides of the bottom of the housing of the harmonic processing module 6 corresponding to the protrusions 54. The protrusions 54 cooperate with the limiting holes to precisely limit the position of the harmonic processing module 6 and ensure accurate installation.

[0051] The working principle of the locking component 53 is as follows: First, the harmonic processing module 6 is calibrated and positioned based on the protrusion 54. The harmonic processing module 6 is placed on the mounting bracket 5 so that the slot hook part 61 is horizontally aligned with the position of the limiting rod 535. Then, the screw 537 is rotated, which drives the slider 534 to move upward along the opening direction of the strip hole 52. When the slider 534 moves upward, it simultaneously drives the lower end of the deflection rod 533 to move upward and deflect. This causes the deflection rod 533 to push the deflection seat 531 upward based on the fixed point of the strip hole 52, thereby gradually bringing the limiting rod 535 closer and finally locking it into the slot hook part 61 to complete the locking. For disassembly, simply rotate the screw 537 in the opposite direction, which is convenient.

[0052] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A power quality management device for photovoltaic power station distribution networks, characterized in that, The enclosure includes a housing (1) and a terminal block (11) fixedly connected to the top of the housing (1). A slot is provided between the inner walls of the housing (1). A first current equalization plate (2) and a second current equalization plate (3) are movably inserted into the slot in sequence. A high-frequency isolation converter (4) is fixedly connected to the top of the first current equalization plate (2). A mounting bracket (5) is fixedly connected to the top of the second current equalization plate (3). A harmonic processing module (6) and a multi-terminal energy router (7) are arranged sequentially on the top of the mounting bracket (5). A DC connection port (8) is fixedly installed on the outer wall of one side of the housing (1). The multi-terminal energy router (7) is electrically connected to the DC connection port (8) through a wire. The harmonic processing module (6) includes: Circuit breakers connected in parallel to the power grid busbar; An LCL filter bank connected to the output terminal of the circuit breaker; a common IGBT three-phase bridge with an AC side connected to the inverter side of the LCL filter bank and a DC bus capacitor and energy storage unit connected to the DC side. And a multi-functional controller that is respectively connected to the PCC, the DC bus capacitor and the IGBT three-phase bridge signal; The multi-functional controller integrates a harmonic extraction algorithm module, a reactive power / voltage droop control module, and a mode switching logic module. It is used to control the output of the shared IGBT three-phase bridge to provide corresponding compensation current based on the detected electrical quantities of the power grid, so as to simultaneously achieve harmonic suppression, reactive power compensation, and voltage regulation.

2. The power quality management device for photovoltaic power station distribution networks according to claim 1, characterized in that: Hollow fin plates (15) are fixedly connected at even intervals around the side walls and door of the box body (1). The inner cavity of the hollow fin plate (15) is connected to the box body (1). A reinforcing rod (151) is fixedly connected to the upper and lower side walls of the hollow fin plate (15) on each side of the box body (1). The reinforcing rod (151) is located at the end of the hollow fin plate (15) away from the box body (1).

3. The power quality management device for photovoltaic power station distribution networks according to claim 2, characterized in that: An inner groove (152) is provided between the hollow fins (15) on the outside of the DC connection port (8). The DC connection port (8) is fixedly connected to the side wall of the box (1) between the inner grooves (152), and the end of the DC connection port (8) is stored in the port of the inner groove (152).

4. The power quality management device for photovoltaic power station distribution networks according to claim 1, characterized in that: The bottom plate of the box (1) is integrally formed with an installation cylinder (12), and a fixed bracket (13) is fixedly connected to the inner wall of the installation cylinder (12). A cooling fan (14) is fixedly connected to the end of the fixed bracket (13), and an exhaust valve pipe (9) is fixedly connected to the top of the box (1) in sequence.

5. The power quality management device for photovoltaic power station distribution networks according to claim 4, characterized in that: The exhaust valve pipe (9) includes a convex-shaped cylinder (91) fixedly connected to the top of the box (1) and in communication with it. The lower end of the convex-shaped cylinder (91) extends into the interior of the box (1). An isolation cover (92) with an air hole at the lower end is fixedly connected to the outer wall of the top port of the convex-shaped cylinder (91). A rotating shaft (93) is rotatably connected to the lower end of the top plate of the isolation cover (92). The lower end of the rotating shaft (93) extends into the convex-shaped cylinder (91). A fixed plate (931) is fixedly connected to the outer wall of the rotating shaft (93) inside the isolation cover (92). A sealing arc plate (94) is movably connected at even intervals at the lower edge of the fixed plate (931). The sealing arc plates (94) are fitted together to form a frustum-shaped sealing cover. A vortex fan (932) is fixedly connected to the bottom of the rotating shaft (93).

6. The power quality management device for photovoltaic power station distribution networks according to claim 5, characterized in that: A rubber ring (95) is fixedly connected to the outer wall of the rotating shaft (93) at the lower end of the sealing arc plate (94). A movable ring (96) is movably sleeved on the outer wall of the rotating shaft (93) of the rubber ring (95). A return spring (97) is fixedly connected between the rubber ring (95) and the movable ring (96). A connecting strip (98) is fixedly connected to the top edge of the movable ring (96) at the corresponding position of the sealing arc plate (94). The top end of the connecting strip (98) moves through the rubber ring (95) and is fixedly connected to the inner wall at the lower end of the sealing arc plate (94).

7. The power quality management device for photovoltaic power station distribution networks according to claim 6, characterized in that: The top of the rubber ring (95) is flush with the top port of the convex cylinder (91). When the reset spring (97) is in a normal relaxed state, the lower sidewalls of the sealing arc plate (94) are in contact with each other, and the lower end of the sealing arc plate (94) is tightly in contact with the top outer wall of the port of the convex cylinder (91).

8. The power quality management device for photovoltaic power station distribution networks according to claim 1, characterized in that: The mounting bracket (5) has a boss (51) fixedly connected to one end of its top. The multi-terminal energy router (7) is fixedly connected to the upper end of the boss (51). The mounting bracket (5) on the outside of the boss (51) has strip holes (52) on both sides of its top. Locking parts (53) are provided in the strip holes (52). The bottom sides of the housing of the harmonic processing module (6) are provided with slot hooks (61) corresponding to the locking parts (53).

9. The power quality management device for photovoltaic power station distribution networks according to claim 8, characterized in that: The locking member (53) is used to detachably fix the harmonic processing module (6). The mounting bracket (5) between the locking members (53) has protrusions (54) fixedly connected on both sides of the top. The bottom sides of the housing of the harmonic processing module (6) are provided with limit holes corresponding to the protrusions (54).

10. The power quality management device for photovoltaic power station distribution networks according to claim 9, characterized in that: The locking component (53) includes deflector seats (531) rotatably connected between the inner walls of the two ends of two strip holes (52). One of the deflector seats (531) has a through hole (532) on its side wall at both ends. A deflector rod (533) is movably connected between the inner walls of the through hole (532). A slider (534) is fixedly connected to the end of the deflector rod (533). The slider (534) is movably engaged within the strip hole (52). The deflector seat (531)... 31) A limiting rod (535) is fixedly connected between the side walls. The limiting rod (535) is perpendicular to the strip hole (52) and is set corresponding to the groove hook part (61). A gantry frame (536) is fixedly connected to the top of the mounting bracket (5) above the slider (534). The gantry frame (536) is suspended horizontally above the strip hole (52). A screw (537) is rotatably connected to the top of the gantry frame (536). The lower end of the screw (537) is threaded into the inside of the slider (534).

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