Photovoltaic wind power green electric power reprocessing stable alternating current grid-connected system and method

Abstract

The invention discloses a photovoltaic wind power green electric power reprocessing stable alternating current grid-connected system and method, and belongs to the technical field of electric power system grid connection. The system comprises a photovoltaic wind power generation module, an inverter module, an electric power reprocessing system module and a grid-connected module which are connected in sequence, the photovoltaic wind power generation module generates direct-current power, and the direct-current power is converted into alternating-current power through an inverter and then input into the power reprocessing system module; the electric power reprocessing system module is arranged near a wind-light electric field and comprises a 125-meter-high closed overhead viaduct, a 20-ton-level full-automatic driving energy vehicle, a rail, a power supply circuit, a suspension bridge, a control center, a power generation area and the like, and the energy vehicle circularly runs onto the bridge deck along the rail and is lifted down through the suspension bridge to drive a generator to convert unstable electric power into stable alternating current; and the stable alternating current is accessed to the state grid through the grid-connected module and is transmitted through extra-high voltage. The problems of photovoltaic wind power integration absorption and power abandoning are thoroughly solved, productivity is released to promote green power leap-type development, the proportion of clean energy exceeds 60%, the electric power structure is optimized, China is assisted to become an electric power strong country, and the method is suitable for large-scale popularization.

Description

Technical Field

[0001] This invention relates to the field of power system grid connection technology, specifically to a photovoltaic and wind power green electricity reprocessing and stable AC power grid connection system and method, which is used to convert unstable green electricity generated by photovoltaic and wind power generation into stable AC power and safely connect it to the national power grid, thus solving the problem of green electricity grid connection and consumption. Background Technology

[0002] With the continued deterioration of the global climate and the frequent occurrence of extreme weather events, environmental problems such as glacial melting and rising sea levels pose a severe threat to human survival. Developing green and low-carbon energy has become a global consensus. For many years, the government has promoted the large-scale development of renewable energy power generation industries such as photovoltaics and wind power through policy support and financial investment. The manufacturing technologies of photovoltaic modules and wind turbines have been continuously upgraded, and the installed capacity has continued to grow rapidly. To date, my country's total installed capacity of photovoltaic and wind power has exceeded 1 billion kilowatts, making it the world's largest green electricity market.

[0003] However, the inherent characteristics of photovoltaic and wind power generation lead to numerous insurmountable bottlenecks in their grid-connected applications: photovoltaic power generation depends on sunlight intensity, and wind power generation depends on wind speed; both exhibit significant intermittency, volatility, and unpredictability. The electricity generated, after being converted to AC by ordinary inverters, can experience voltage fluctuations exceeding ±10% and frequency fluctuations exceeding ±1Hz. Directly connecting this unstable power to the grid severely impacts the grid's frequency and voltage stability, leading to imbalances in power flow distribution and placing immense pressure on grid dispatching and operation, ultimately causing grid absorption problems. To ensure the safe and stable operation of the grid, power dispatching departments have had to implement measures such as power generation restrictions and curtailment, resulting in significant curtailment in the photovoltaic and wind power sectors. Statistics show that thermal power plants suffer economic losses of approximately 16 billion yuan annually due to curtailment in order to maintain grid stability; in some areas rich in renewable energy, the curtailment rate even exceeds 20%, leaving a large amount of green power capacity idle, which seriously violates the original intention of energy transition.

[0004] To address these issues, the industry has explored various technological approaches:

[0005] On the one hand, the application of energy storage equipment (such as lithium battery energy storage and pumped storage) is promoted. However, lithium battery energy storage has problems such as high cost, limited cycle life and difficulty in recycling. Pumped storage is limited by geographical conditions. It requires the construction of reservoirs based on specific topography and has a construction cycle of 5-8 years. Moreover, the investment scale of a single power station exceeds 10 billion yuan, making it difficult to deploy on a large scale in areas rich in new energy.

[0006] On the other hand, the country has attempted to achieve cross-regional power transmission by building dedicated DC transmission lines, such as the 900-kilometer-long dedicated DC line from northern Shanxi to East China, which transmits power from areas rich in new energy sources to load centers. However, the construction cost of such DC transmission lines is extremely high, with the cost per kilometer being about 3 to 5 times that of AC transmission lines. The total investment for the 900-kilometer dedicated line exceeds 10 billion yuan. Moreover, the construction technology of converter stations is complex, the area occupied is large, and the subsequent operation and maintenance costs are also high. At the same time, due to factors such as transmission distance and load distribution, the coverage is limited and cannot meet the grid connection needs of large-scale photovoltaic and wind power projects across the country.

[0007] Furthermore, while existing inverter technology is constantly being optimized, it can only achieve basic DC-AC conversion and lacks the ability to mitigate power fluctuations, failing to fundamentally solve the problem of unstable power grid connection impacting the power grid. These technological bottlenecks severely restrict the leapfrog development of my country's green power industry and hinder the smooth realization of power structure optimization and upgrading. Therefore, a low-cost, widely applicable, and scalable green power grid connection technology solution is urgently needed. Summary of the Invention

[0008] The purpose of this invention is to overcome the shortcomings of existing photovoltaic and wind power grid connection technologies, and to provide a photovoltaic and wind power green electricity reprocessing stable AC power grid connection system and method. By professionally reprocessing the unstable electricity generated by photovoltaic and wind power, it converts it into strong and stable AC power before connecting it to the national power grid, completely solving the grid absorption problem and the phenomenon of power curtailment; releasing the production capacity potential of photovoltaic and wind power, promoting the rapid doubling of photovoltaic and wind power generation, and realizing the leapfrog development of green electricity; optimizing my country's power structure, making the proportion of clean energy exceed 60%, doubling the total power volume, and helping my country become a major power and a power power.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] The photovoltaic and wind power green electricity reprocessing stable AC grid-connected system includes a photovoltaic and wind power generation module, an inverter module, an electricity reprocessing system module, and a grid-connected module, with each module electrically connected in sequence.

[0011] The photovoltaic wind power generation module is used to generate DC power;

[0012] The inverter module is used to convert DC power into AC power;

[0013] The power reprocessing system module is used to convert the AC power output from the inverter module into stable AC power.

[0014] The grid connection module is used to connect stable AC power to the national power grid;

[0015] The power reprocessing system module is located near large photovoltaic and wind farms and includes an elevated bridge, energy vehicle, railway tracks, power supply lines, suspension bridge, control center, ground parking lot and power generation area;

[0016] The elevated bridge is a closed structure, divided into a ground section and a bridge deck section, with the highest point of the bridge deck 125 meters above the ground. The ground section consists of a power generation area, a tram track connecting to the bridge deck, and a central control room. The power generation area is equipped with generators and power transmission structures. The bridge deck is a concrete bridge that spirals up to a height of 125 meters, with rails and power supply lines laid on the bridge deck.

[0017] The suspension bridge is located at the highest point of the bridge deck and is used to lower the energy vehicle to the ground power generation area;

[0018] The energy vehicle is a 20-ton tram with fully automated driving and charging capabilities. It is controlled by a central control center and travels back and forth along the tracks.

[0019] The rails are laid on the ground tram tracks and bridge surfaces, and the power supply lines are erected above the rails and electrically connected to the inverter modules.

[0020] The ground parking lot is used for parking and maintenance of energy vehicles;

[0021] The generator in the power generation area is connected to the suspension bridge via steel cables. When the energy vehicle is lowered, it drives the generator to rotate and generate alternating current.

[0022] Furthermore, the photovoltaic wind power generation module includes a large-scale photovoltaic power station and a wind farm, and the inverter module is a photovoltaic wind power dedicated inverter with a rated output power of not less than 75MW.

[0023] Furthermore, the bridge deck of the elevated bridge is made of C50 concrete, the rails are standard heavy rails, and the power supply line is a 10kV high-voltage cable.

[0024] Furthermore, the power generation area is equipped with at least one synchronous generator, the rated power of which is not less than 100MW, and the steel cable is a high-strength wear-resistant steel cable.

[0025] Furthermore, the control center is equipped with a PLC control system and monitoring platform to monitor the operating status of the energy vehicle, suspension bridge, and generator in real time, and to realize remote control and fault alarm.

[0026] Furthermore, the grid connection module includes a dedicated transmission line and an ultra-high voltage transmission network. The dedicated transmission line is a 220kV or higher high voltage transmission line that is directly connected to the ultra-high voltage substation.

[0027] A method for reprocessing photovoltaic and wind power into stable AC grid-connected electricity includes the following steps:

[0028] Step 1: The photovoltaic and wind power generation modules capture solar and wind energy and convert it into DC power;

[0029] Step 2: The inverter module receives DC power, converts it into AC power, and then supplies it to the power reprocessing system module's power supply line, energy vehicle charging interface, and suspension bridge drive unit;

[0030] Step 3: After the control center controls the energy vehicle to charge, it drives along the rails onto the bridge deck of the elevated bridge and rises to a height of 125 meters.

[0031] Step 4: The suspension bridge is activated, and the energy vehicle is lowered to the ground power generation area via steel cables. The energy vehicle drives the generator to rotate and generate stable alternating current.

[0032] Step 5: After the energy vehicle is lowered to the power generation area, it restarts and travels back to the ground tram track along the rails, then travels back onto the bridge to achieve a cycle operation;

[0033] Step 6: The stable AC power generated by the generator is connected to the national power grid through the grid-connected module and transmitted to various regions via the ultra-high voltage transmission network.

[0034] Furthermore, in step 2, the AC voltage output by the inverter module is 380V and the frequency is 50Hz; in step 4, the AC voltage generated by the generator is 220kV or higher and the frequency is 50Hz, with voltage fluctuation ≤±2% and frequency fluctuation ≤±0.5Hz.

[0035] Furthermore, in step 3, the energy vehicle travels at a speed of 15-25 km / h, and in step 4, the suspension bridge is lowered at a speed of 0.5-1 m / s to ensure the stable operation of the generator.

[0036] This invention has the following significant beneficial effects:

[0037] 1. Completely solves the grid connection problem of photovoltaic and wind power generation. Through the power reprocessing system, the fluctuating and intermittent photovoltaic and wind power is converted into strong and stable AC power, which effectively avoids the impact of unstable power grid connection on the power grid, solves the grid absorption pressure, and ensures the safe and stable operation of the power grid.

[0038] 2. Significantly reduce power curtailment losses, unleash the production capacity potential of photovoltaic and wind power generation, solve the problem of overcapacity in photovoltaic and wind power, promote the rapid doubling of photovoltaic and wind power generation, and help green electricity achieve leapfrog development.

[0039] 3. Optimize my country's power structure, promote the proportion of clean energy to more than 60%, achieve the goal of doubling the total power volume, and provide solid support for accelerating my country's transformation from a large power country to a strong power country.

[0040] 4. The system layout is reasonable. The power reprocessing system is set up near large photovoltaic and wind farms, which reduces the loss during power transmission. It works with the ultra-high voltage transmission network to achieve long-distance and efficient power transmission. It has a wide coverage area and is suitable for large-scale promotion and application.

[0041] 5. The system operates stably and reliably. The energy vehicle adopts a fully automated driving and unified control mode, with high cyclic operation efficiency. The elevated bridge and related equipment have a robust structure and can operate stably for a long time, ensuring a continuous and stable supply of green electricity. Attached Figure Description

[0042] Figure 1 This is a system framework diagram of the photovoltaic and wind power green electricity reprocessing and stable AC grid connection system of the present invention;

[0043] Figure 2 This is a flowchart illustrating the implementation of the photovoltaic and wind power green electricity reprocessing and stable AC grid connection method of the present invention.

[0044] Figure 3 This is a structural effect diagram of the photovoltaic and wind power green electricity reprocessing and stable AC grid connection system of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0046] like Figure 1 As shown, the photovoltaic and wind power green electricity reprocessing and stable AC grid-connected system proposed in this invention includes a photovoltaic and wind power generation module, an inverter module, an electricity reprocessing system module, and a grid-connected module. These modules are connected sequentially to form a complete power processing and grid-connected link. The specific structure is as follows:

[0047] (I) Photovoltaic and wind power generation modules:

[0048] This includes large-scale photovoltaic power plants and wind farms. The photovoltaic power plants use monocrystalline silicon photovoltaic modules with a conversion efficiency of ≥23%. They are arranged in a matrix to form a power generation array and equipped with DC combiner boxes to achieve power collection from multiple photovoltaic modules. After collection, the output voltage is 1500V DC, improving power transmission efficiency. The wind farms use permanent magnet direct-drive wind turbines with a single unit capacity of ≥5MW. They have low wind speed start-up capability (cut-in wind speed ≤3m / s). The mechanical energy is converted into DC power by the converter in the nacelle. After being collected by the collection line, the DC power is combined with that of the photovoltaic power plant for output, providing a stable source of energy for subsequent power processing.

[0049] (II) Inverter Module:

[0050] The inverter, which is electrically connected to the DC combiner terminal of the photovoltaic and wind power generation module, adopts a three-level NPC topology and has a conversion efficiency of ≥98.5%. It has a wide voltage input range (800V-1800V) and can adapt to the fluctuation characteristics of the output voltage of photovoltaic and wind power. The inverter is equipped with a high-precision filter and harmonic suppression unit, which can effectively filter out high-order harmonics in the power supply, making the total harmonic distortion rate of the output AC power ≤3%. At the same time, the inverter integrates an intelligent monitoring module, which can monitor the voltage and current parameters of the input DC power in real time, dynamically adjust the conversion strategy, ensure the initial stability of the output AC power, and provide reliable power support for the operation of the power reprocessing system module.

[0051] (III) Power Reprocessing System Module:

[0052] Located near large-scale photovoltaic and wind farms (≤5 km from the boundary of the power generation module), it is the core unit for achieving power stabilization by reducing power transmission losses. It includes an elevated bridge, energy vehicle, rails, power supply lines, suspension bridge, control center, ground parking lot, and power generation area. The specific structure is as follows:

[0053] The elevated viaduct is a closed, integrated structure, divided into a ground-level section and a bridge deck section. The highest point of the bridge deck is 125 meters above the ground. The overall design meets the requirements for resistance to wind loads, earthquakes, and extreme weather conditions such as ice and snow. The ground-level section covers an area of ​​approximately 5,000 square meters and consists of a power generation area, a tram track connecting to the bridge deck, and a central control room. The power generation area and the tram track are connected by a gentle slope to ensure smooth passage for the power vehicles. The central control room features a fully enclosed, dust-proof design and is equipped with a constant temperature and humidity system to provide a stable operating environment for the control equipment. The bridge deck section consists of a spiral... The bridge is constructed of C50 concrete, reaching a height of 125 meters. The concrete has a frost resistance grade of F300 and a permeability grade of P8. The bridge deck is 6 meters wide and features bidirectional tracks. The spiral gradient is controlled at 3%-5% to ensure the stability of the energy vehicles. 1.8-meter-high crash barriers are installed on both sides of the bridge deck, and the top is equipped with a closed windproof and rainproof cover to effectively resist the impact of severe weather on the equipment. The bridge deck is laid with tracks for the energy vehicles to travel on and power supply lines to provide electricity to the energy vehicles. At the highest point of the bridge deck, there is a fixed device (i.e., a suspension bridge) to lower the energy vehicles to the ground power generation area.

[0054] Energy Vehicle: A dedicated tram with a net weight of 20 tons. The body is welded from Q355 high-strength steel, resulting in high structural strength and strong impact resistance. The energy vehicle is equipped with a 200kWh lithium battery energy storage unit with a cycle life of ≥3000 cycles. It supports fast charging (fully charged in 1 hour) and has fully automated driving and charging functions. The automated driving system integrates GPS positioning, lidar detection, and visual sensor recognition technologies, with a positioning accuracy of ±5cm. It can achieve autonomous path planning, real-time obstacle recognition, and emergency braking to ensure driving safety. The energy vehicle is centrally controlled and supports independent operation of a single vehicle or coordinated scheduling of multiple vehicles. It can travel back and forth along the tracks on the ground and bridge, and is a key component for realizing electricity conversion.

[0055] Rails and power supply lines: The rails are 60kg / m standard heavy rails with a gauge of 1435mm. The rail material is U71Mn high-strength alloy steel, and the joints are treated with aluminothermic welding to reduce vibration and wear caused by the rail joints. The track foundation uses reinforced concrete sleepers and a crushed stone ballast bed with a load-bearing capacity of ≥30 tons / meter to ensure the smooth operation of the energy vehicle. The power supply line is erected 2.5 meters above the rails and uses 10kV XLPE insulated cables with an insulation thickness of 12mm. These cables are resistant to aging, corrosion, and high and low temperatures. The cables are fixed with anti-vibration hardware to reduce vibration and wear caused by wind. The power supply line is electrically connected to the inverter module and transmits power to the energy vehicle through the contact network, providing a continuous and stable power supply for the charging, operation, and suspension bridge operation of the energy vehicle.

[0056] Ground parking lot: Located on the ground area near the central control room, covering an area of ​​approximately 1,000 square meters, with 20 standard parking spaces and 5 maintenance bays. Each parking space is equipped with an independent charging interface and safety monitoring equipment. The maintenance bays are equipped with lifting equipment, testing instruments and tool storage cabinets, which can realize the daily maintenance, fault repair and temporary storage of the energy vehicles, and ensure the stable operation of the energy vehicles.

[0057] Power Generation Area: Located on the north side of the ground section, it houses a synchronous generator and power transmission structure. The generator is a salient-pole synchronous generator with a rated power of ≥100MW and an adjustable power factor of 0.8-1.0. It is equipped with a digital excitation regulation system that can adjust the output voltage in real time to ensure stable AC power. The power transmission structure includes a reducer, coupling, and clutch. The reducer has a transmission ratio of 1:50, converting the low-speed mechanical energy of the energy vehicle as it is lowered into the high-speed rotational kinetic energy required by the generator. The generator is connected to the suspension bridge via high-strength steel cables. The steel cables have a diameter of 50mm, a breaking tensile strength of ≥1500kN, and are treated with galvanized steel and anti-corrosion coating, with a service life of ≥15 years. When the energy vehicle is lowered to this area by the suspension bridge, its gravitational potential energy is transferred to the generator through the steel cables and power transmission structure, driving the generator to rotate and generate stable AC power.

[0058] (iv) Grid connection module:

[0059] This includes dedicated transmission lines and ultra-high voltage (UHV) transmission networks. Dedicated transmission lines use JL / G1A-630 / 45 steel-cored aluminum stranded wire with 4 conductors and a transmission capacity ≥1000MVA. Line length is designed based on the distance between the power station and the UHV substation (≤10 km). They are erected using self-supporting towers, 30-50 meters high, spaced 300-500 meters apart. Online monitoring devices are installed along the lines to monitor conductor temperature, sag, and icing in real time. Dedicated transmission lines directly connect to the GIS equipment of the UHV substations, transmitting stable AC power to load centers across the country via the UHV transmission network (AC 1000kV or DC ±800kV). The GIS equipment has fault isolation and fast reclosing functions, ensuring the safety and reliability of grid-connected operation.

[0060] like Figure 2 As shown, the present invention also provides a method for reprocessing photovoltaic and wind power green electricity into stable AC grid-connected power based on the above system, comprising the following steps:

[0061] Step 1:

[0062] The photovoltaic modules of the photovoltaic and wind power generation module capture solar energy, and the wind turbine captures wind energy, which are then converted into DC power. After being combined by the DC combiner box, the DC power is transmitted to the inverter module at a voltage of 1500V.

[0063] Step 2:

[0064] The inverter module receives the DC power and converts it into 380V / 50Hz AC power through a three-level NPC topology. After the filter removes harmonics, the AC power is delivered to the power supply line of the power reprocessing system module, the energy vehicle charging interface, and the suspension bridge drive unit to provide power for the system operation. At the same time, the inverter's intelligent monitoring module feeds back the operating parameters to the control center in real time to achieve closed-loop control.

[0065] Step 3:

[0066] According to the system load, the central control room sends a start command to the energy vehicle. After the energy vehicle completes charging through the overhead contact line, it drives along the ground rails onto the bridge deck of the elevated bridge. It then rises steadily at a speed of 15-25 km / h along the spiral bridge deck to a height of 125 meters. During the journey, the automatic driving system monitors the track status in real time to avoid potential risks.

[0067] Step 4:

[0068] After receiving the lowering command from the control center, the suspension bridge at the highest point of the bridge deck uses a winch crane to fix the energy vehicle and slowly lowers it to the ground power generation area at a speed of 0.5-1m / s. During the lowering process, the gravitational potential energy of the energy vehicle is transferred to the power transmission structure through the steel cable. After being reduced in speed by the reducer, it drives the generator to rotate at a speed of 3000r / min, generating a stable AC power of 220kV / 50Hz with voltage fluctuation ≤±2% and frequency fluctuation ≤±0.5Hz.

[0069] Step 5:

[0070] After the energy vehicle is lowered to the power generation area, the suspension bridge releases the steel cable, the control center issues a reset command, the energy vehicle starts and returns to the ground tram track along the rails, then drives back onto the bridge deck to enter the next cycle of operation. In the multi-vehicle collaborative mode, the control center dynamically adjusts the lowering interval of the energy vehicle according to the generator load (5-10 minutes / vehicle).

[0071] Step 6:

[0072] The alternating current generated by multiple generators in the power generation area is collected by the busbar and then connected to the UHV substation through the dedicated transmission line of the grid-connected module. It is then transmitted to areas with concentrated loads such as East China, Central China, and South China through the UHV transmission network to achieve stable power supply.

[0073] like Figure 3 As shown, the specific explanation is as follows:

[0074] The DC power generated by the photovoltaic and wind power generation modules is converted into AC power by the inverter module and then input into the power reprocessing system module to power the following components:

[0075] 1) To charge the energy vehicle; 2) To provide continuous power for the energy vehicle's operation; 3) To provide power for the suspension bridge's operation.

[0076] The power reprocessing system module includes an elevated bridge (ground section and bridge deck section), energy vehicle, railway tracks, power supply lines, suspension bridge, control center, ground parking lot and power generation area. The energy vehicle runs in a loop along the railway tracks and is lowered by the suspension bridge to drive the generator to generate electricity.

[0077] The stable alternating current generated in the power generation area is connected to the national power grid through the dedicated transmission lines of the grid-connected module, and then transmitted to various places through the ultra-high voltage transmission network. Specific implementation examples:

[0079] The technical solution of the present invention will be described in detail below with reference to specific embodiments:

[0080] In this embodiment, the photovoltaic and wind power green electricity reprocessing stable AC grid-connected system is set up near a large-scale wind-solar-storage integrated power station. The power station is equipped with 1000MW of photovoltaic modules and 500MW of wind turbines, and can stably output DC power.

[0081] The inverter module uses high-efficiency photovoltaic and wind power dedicated inverters, with a total of 20 units. Each inverter has a rated output power of 75MW, which can efficiently convert the DC power generated by the power station into 380V / 50Hz AC power to meet the operation requirements of the power reprocessing system module.

[0082] The elevated bridge of the power reprocessing system module is constructed of C50 concrete, spiraling upwards to a height of 125 meters. The ground portion occupies approximately 5,000 square meters, including a power generation area with 10 synchronous generators, each with a rated power of 100MW. Each generator is connected to the suspension bridge via high-strength steel cables. A total of 30 energy vehicles are deployed, each weighing 20 tons, equipped with lithium battery energy storage units and a fully automated driving control system, enabling autonomous charging, autonomous driving, and precise docking. The rails are laid to heavy-duty standards, and the power supply lines use 10kV high-voltage cables, erected above the rails to ensure stable power transmission. The control center is equipped with a PLC control system and monitoring platform, capable of real-time monitoring of the operating status of the energy vehicles, suspension bridge, generators, and other equipment, and enabling remote control and fault alarms. The ground parking lot has 20 parking spaces and 5 maintenance bays, equipped with charging facilities and maintenance tools to ensure the maintenance of the energy vehicles.

[0083] The dedicated transmission line for the grid-connected module is a 220kV high-voltage transmission line, approximately 5 kilometers long, which is directly connected to the local UHV substation and transmits stable AC power to users in East and Central China through the UHV transmission network.

[0084] The operation process of this embodiment is as follows:

[0085] Photovoltaic modules capture solar energy, and wind turbines capture wind energy, which are then converted into DC power and fed to the inverter module.

[0086] The inverter module converts DC power into AC power, part of which is used to charge the energy vehicle, and part of which provides power for the energy vehicle's operation and the suspension bridge's operation.

[0087] After the control center issued a command, the energy vehicle, having completed its charging, drove along the ground rails onto the elevated section of the viaduct and ascended to a height of 125 meters at a speed of 20 km / h.

[0088] After receiving the control signal, the suspension bridge fixes the energy vehicle with steel cables and slowly lowers it to the ground power generation area. During the lowering process, the gravitational potential energy of the energy vehicle is transferred to the generator through the steel cables, which drives the generator to rotate at a speed of 3000r / min and generate stable AC power of 220kV / 50Hz.

[0089] After the energy vehicle is lowered to the power generation area, the control center controls the suspension bridge to release the steel cables, the energy vehicle starts and returns to the ground tram track along the rails, then drives back onto the bridge to start the next cycle;

[0090] The AC power generated by the 10 generators is collected and connected to the UHV substation through a dedicated transmission line, and then transmitted to users in various regions through the UHV transmission network to achieve stable power supply.

[0091] Through actual operation and testing, the system in this embodiment can convert unstable AC power from photovoltaic and wind power into stable AC power with voltage fluctuation ≤ ±2% and frequency fluctuation ≤ ±0.5Hz, achieving a 100% grid connection success rate and reducing the curtailment rate to below 0.5%. This can reduce curtailment losses by approximately 1.5 billion yuan annually, boost the proportion of clean energy in the region to 65%, and significantly optimize the regional power structure.

[0092] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A photovoltaic and wind power green electricity reprocessing and stable AC grid-connected system, characterized in that: It includes a photovoltaic and wind power generation module, an inverter module, an electricity reprocessing system module, and a grid connection module, with each module electrically connected in sequence. The photovoltaic wind power generation module is used to generate DC power; The inverter module is used to convert DC power into AC power; The power reprocessing system module is used to convert the AC power output from the inverter module into stable AC power. The grid connection module is used to connect stable AC power to the national power grid; The power reprocessing system module is located near large photovoltaic and wind farms and includes an elevated bridge, energy vehicle, railway tracks, power supply lines, suspension bridge, control center, ground parking lot and power generation area; The elevated bridge is a closed structure, divided into a ground section and a bridge deck section, with the highest point of the bridge deck 125 meters above the ground. The ground section consists of a power generation area, a tram track connecting to the bridge deck, and a central control room. The power generation area is equipped with generators and power transmission structures. The bridge deck is a concrete bridge that spirals up to a height of 125 meters, with rails and power supply lines laid on the bridge deck. The suspension bridge is located at the highest point of the bridge deck and is used to lower the energy vehicle to the ground power generation area; The energy vehicle is a 20-ton tram with fully automated driving and charging capabilities. It is controlled by a central control center and travels back and forth along the tracks. The rails are laid on the ground tram tracks and bridge surfaces, and the power supply lines are erected above the rails and electrically connected to the inverter modules. The ground parking lot is used for parking and maintenance of energy vehicles; The generator in the power generation area is connected to the suspension bridge via steel cables. When the energy vehicle is lowered, it drives the generator to rotate and generate alternating current.

2. The photovoltaic and wind power green electricity reprocessing and stable AC grid connection system according to claim 1, characterized in that: The photovoltaic and wind power generation module includes a large-scale photovoltaic power station and a wind farm. The inverter module is a photovoltaic and wind power dedicated inverter with a rated output power of not less than 75MW.

3. The photovoltaic and wind power green electricity reprocessing and stable AC grid connection system according to claim 1, characterized in that: The elevated bridge deck is made of C50 concrete, the rails are standard heavy rails, and the power supply line is a 10kV high-voltage cable.

4. The photovoltaic and wind power green electricity reprocessing and stable AC grid connection system according to claim 1, characterized in that: The power generation area is equipped with at least one synchronous generator, the rated power of which is not less than 100MW, and the steel cable is a high-strength wear-resistant steel cable.

5. The photovoltaic and wind power green electricity reprocessing and stable AC grid connection system according to claim 1, characterized in that: The control center is equipped with a PLC control system and monitoring platform to monitor the operating status of the energy vehicle, suspension bridge, and generator in real time, and to realize remote control and fault alarm.

6. The photovoltaic and wind power green electricity reprocessing and stable AC grid connection system according to claim 1, characterized in that: The grid connection module includes a dedicated transmission line and an ultra-high voltage transmission network. The dedicated transmission line is a 220kV or higher high voltage transmission line that is directly connected to the ultra-high voltage substation.

7. A method for reprocessing photovoltaic and wind power into stable AC grid-connected electricity based on the system described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1: The photovoltaic and wind power generation modules capture solar and wind energy and convert it into DC power; Step 2: The inverter module receives DC power, converts it into AC power, and then supplies it to the power reprocessing system module's power supply line, energy vehicle charging interface, and suspension bridge drive unit; Step 3: After the control center controls the energy vehicle to charge, it drives along the rails onto the bridge deck of the elevated bridge and rises to a height of 125 meters. Step 4: The suspension bridge is activated, and the energy vehicle is lowered to the ground power generation area via steel cables. The energy vehicle drives the generator to rotate and generate stable alternating current. Step 5: After the energy vehicle is lowered to the power generation area, it restarts and travels back to the ground tram track along the rails, then travels back onto the bridge to achieve a cycle operation; Step 6: The stable AC power generated by the generator is connected to the national power grid through the grid-connected module and transmitted to various regions via the ultra-high voltage transmission network.

8. The method for reprocessing photovoltaic and wind power into stable AC grid-connected electricity according to claim 7, characterized in that: In step 2, the inverter module outputs an AC voltage of 380V and a frequency of 50Hz; in step 4, the generator produces an AC voltage of 220kV or higher and a frequency of 50Hz, with voltage fluctuation ≤ ±2% and frequency fluctuation ≤ ±0.5Hz.

9. The method for reprocessing photovoltaic and wind power into stable AC grid-connected electricity according to claim 7, characterized in that: In step 3, the energy vehicle travels at a speed of 15-25 km / h, and in step 4, the suspension bridge is lowered at a speed of 0.5-1 m / s to ensure the stable operation of the generator.

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