Electrical main wiring system for connecting new energy circuit to hydraulic power plant

Abstract

The invention provides an electrical main wiring system for accessing a new energy circuit to a hydraulic power plant, which comprises an autotransformer, the autotransformer is respectively connected with a 500kV branch bus, a 220kV branch bus and a 35kV branch bus, the 500kV branch bus is connected with a 500kV main bus, the 220kV branch bus is connected with a 220kV main bus, and at least one 220kV new energy circuit is arranged on the 220kV main bus; the 35kV branch bus is connected with the 35kV main bus, at least one 35kV new energy line is arranged on the 35kV main bus, and lines on the 220kV side and the 35kV side of the autotransformer are connected to the 500kV main bus after being boosted and collected and are connected to a power grid through a 500kV sending-out line of a hydropower station. Wind power and photovoltaic power are connected into the hydropower station to realize water-wind-light complementary operation, and more wind and light are generated by utilizing water storage in a dry season; in rainy seasons, water is rich, more water and electricity are generated, continuous and stable output of generating capacity is achieved, and the utilization hours of the line are increased. The land cost is reduced, the construction difficulty is reduced, the construction of a sending-out circuit is reduced, and the cost is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of power generation, and in particular to a main electrical connection system for connecting new energy lines to a hydropower plant. Background Art

[0002] The usual access system transmission plan for new energy power plants such as wind power and photovoltaic power plants is to set up a booster station in the wind power and photovoltaic field. The power generation arrays in each area of the field are collected by the collection line to the booster station and boosted to the voltage level of the connected system, and then connected to the local power grid nearby. Or, several wind power and photovoltaic fields are boosted to a certain voltage level (such as 110kV, 220kV) and then bundled and collected to a new energy collection station for unified transmission.

[0003] The mountainous areas of southwestern my country are rich in wind and solar resources, but local electricity demand is limited. Renewable energy consumption is primarily achieved through long-distance transmission (for example, wind and solar power generation in Yunnan is transmitted to Guangdong). These wind and photovoltaic projects are often located in mountainous canyons, far from the local power grid. If bundled transmission is achieved through a new aggregation station, this would require a new station in the mountainous region to gather power from nearby renewable energy power plants, and then a new high-voltage transmission line for long-distance transmission. This approach presents the following challenges for renewable energy power plants in mountainous areas: 1) The complex geology of the surrounding mountains and canyons requires a considerable area of flat land for the new aggregation station, making site selection difficult. 2) The steep terrain limits the available transmission channels for constructing new high-voltage transmission lines in mountainous areas, and construction is difficult and investment-intensive, making them uneconomical. 3) The high volatility of power generation from renewable energy power plants such as wind and photovoltaics often requires the installation of nearby energy storage stations to regulate and balance the output, further increasing the cost and difficulty of constructing renewable energy power plants in canyon areas. Summary of the Invention

[0004] The main purpose of the present invention is to provide an electrical main connection system for connecting new energy lines to a hydropower plant in order to solve the above-mentioned problems.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An electrical main connection system for connecting a new energy line to a hydropower plant, comprising an autotransformer, wherein the autotransformer is connected to a 500kV branch bus, a 220kV branch bus, and a 35kV branch bus, respectively. The 500kV branch bus is connected to a 500kV main bus, and the 220kV branch bus is connected to a 220kV main bus. At least one 220kV new energy line is provided on the 220kV main bus.

[0007] The 35kV branch bus is connected to the 35kV main bus. At least one 35kV new energy line is installed on the 35kV main bus. The 220kV and 35kV side lines of the autotransformer are boosted and connected to the 500kV main bus after being combined, and are connected to the power grid through the 500kV transmission line of the hydropower station.

[0008] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0009] As a preferred technical solution of the present invention: a detachable fracture is reserved on the 220kV branch bus, and a 220kV circuit breaker reserved interval is provided between the detachable fracture and the 220kV main bus.

[0010] As a preferred technical solution of the present invention: a 500kV lightning arrester and a 500kV circuit breaker are provided on the 500kV GIS branch busbar.

[0011] As a preferred technical solution of the present invention: a 35kV lightning arrester and a 35kV circuit breaker are provided on the 35kV branch bus.

[0012] As a preferred technical solution of the present invention: a 220kV bus voltage transformer and a lightning arrester combination is provided on the 220kV main bus.

[0013] As a preferred technical solution of the present invention: a 35kV bus voltage transformer and lightning arrester combination is provided on the 35kV main bus.

[0014] As a preferred technical solution of the present invention: an SVG reactive power compensation device and a capacitor bank are provided on the 35kV main bus.

[0015] As a preferred technical solution of the present invention: a 35kV feeder circuit breaker is provided between the 35kV main bus and the SVG reactive compensation device.

[0016] As a preferred technical solution of the present invention: the third winding of the autotransformer (35kV side winding capacity) is controlled to be no less than 35% of the autotransformer electromagnetic capacity to compensate for the third harmonic current. The autotransformer electromagnetic capacity is calculated according to the following formula:

[0017]

[0018] Where S T is the total capacity of the autotransformer; S C is the electromagnetic capacity of the autotransformer; U2 is the voltage on the medium voltage side of the autotransformer; U1 is the voltage on the high voltage side of the autotransformer.

[0019] As a preferred technical solution of the present invention: circuit breakers are provided on both the 220kV new energy line and the 35kV new energy line.

[0020] The present invention provides an electrical main connection system for connecting new energy lines to a hydropower plant, which has the following beneficial effects: connecting wind power and photovoltaic power to the hydropower station can realize the complementary operation of water, wind and photovoltaic power, utilize water storage in the dry season to generate more wind and photovoltaic power; and utilize abundant water in the rainy season to generate more hydropower, thereby realizing continuous and stable output of power generation and increasing the utilization hours of the line; compared with using a three-winding transformer to connect three voltage levels, using an autotransformer and using a group of common windings for high and medium voltage can reduce the electromagnetic capacity of the transformer, reduce the weight of the transformer and the manufacturing cost, and have better economy; reducing land costs, reducing the difficulty of building a collection station, reducing the construction of transmission circuits, and greatly reducing the access system cost of the wind power and photovoltaic power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the main electrical connection system for connecting the new energy line provided by the present invention to a hydropower plant.

[0022] In the diagram: 1 - autotransformer; 2 - 500kV branch bus; 3 - 500kV lightning arrester; 4 - 500kV circuit breaker; 5 - 500kV main bus; 6 - 220kV branch bus; 7 - 220kV circuit breaker; 8 - 220kV main bus; 9 - 220kV bus voltage transformer and lightning arrester combination; 10 - 220kV new energy line; 11 - reserved 220kV new energy line; 12 - 35k V branch bus; 13-35kV lightning arrester; 14-35kV main bus; 15-35kV circuit breaker; 16-35kV busbar voltage transformer and lightning arrester combination; 17-35kV feeder circuit breaker; 18-SVG reactive power compensation device; 19-capacitor bank; 20-35kV new energy line; 21-reserved 35kV new energy line; 22-500kV transmission line of hydropower station; 23-detachable breakers. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, a main electrical connection system for connecting a new energy line to a hydropower plant includes an autotransformer 1, which is respectively connected to a medium- and high-voltage (hydropower) 500kV branch bus 2, a medium-voltage (wind power) 220kV branch bus 6, and a low-voltage (photovoltaic) 35kV branch bus 12. The 500kV branch bus 2 is connected to a 500kV main bus 5, and the 220kV branch bus 6 is connected to a 220kV main bus 8. At least one 220kV new energy line 10 is provided on the 220kV main bus 8. A reserved 220kV new energy line 11 can be added later as needed.

[0025] The 35kV branch bus 12 is connected to the 35kV main bus 14. At least one 35kV new energy line 20 is provided on the 35kV main bus 14. A reserved 35kV new energy line 21 can be added later as needed. The 220kV side and 35kV side lines of the autotransformer 1 are boosted and connected to the 500kV main bus 5, and then connected to the power grid through the 500kV transmission line 22 of the hydropower station.

[0026] In the early stages of system operation, when there are relatively few 220kV new energy lines 10 connected, a removable break 23 is reserved on the 220kV branch busbar 6, and a reserved gap for a 220kV circuit breaker 7 is provided between the removable break 23 and the 220kV main busbar 8. Specifically, in the early stages of system operation, when only one 220kV new energy line 10 is connected, the 220kV side of the autotransformer 1 is directly connected to the 220kV main busbar 8 via the 220kV branch busbar 6. Later in the operation phase, when a new 220kV new energy line 11 is required, the 220kV branch busbar 6 between the removable break 23 and the 220kV main busbar 8 is disconnected, and the 220kV circuit breaker 7 is connected between the removable break 23 and the 220kV main busbar 8.

[0027] A 500kV lightning arrester 3 and a 500kV circuit breaker 4 are provided on the 500kV GIS branch busbar 2. The 500kV lightning arrester 3 is used to suppress lightning and switching overvoltage.

[0028] The 35kV branch busbar 12 is a copper tube or aluminum tube busbar. A 35kV lightning arrester 13 and a 35kV circuit breaker 15 are provided on the 35kV branch busbar 12. The 35kV lightning arrester is used to suppress lightning and operating overvoltage.

[0029] The 220kV main busbar 8 is provided with a 220kV busbar voltage transformer and lightning arrester combination 9 for suppressing lightning and switching overvoltage.

[0030] A 35kV bus voltage transformer and lightning arrester assembly 16 is provided on the 35kV main bus 14 .

[0031] The 35kV main bus 14 is provided with an SVG reactive power compensation device 18 for compensating for short-term fluctuating reactive power, and a capacitor bank 19 for compensating for long-term relatively stable inductive reactive power, which is switched on and off according to the reactive power situation of the system.

[0032] A 35kV feeder circuit breaker 17 is provided between the 35kV main bus 14 and the SVG reactive power compensation device 18 .

[0033] The total capacity of the autotransformer 1 is determined by the sum of the access capacity of the new energy lines on the medium-voltage side and the low-voltage side and the reactive compensation capacity. The voltage levels of the high, medium and low-voltage sides of the autotransformer 1 are determined according to the corresponding voltages of the systems on each side. In areas with limited transportation conditions such as hydropower stations in canyon areas, single-phase transformer type is selected. If transportation conditions are not limited, three-phase transformer type can be selected. The first and second windings correspond to the 500kV winding and 220kV winding of the autotransformer respectively. The third winding (that is, the winding capacity on the 35kV side) is controlled to be no less than 35% of the electromagnetic capacity of the autotransformer to compensate for the third harmonic current. The electromagnetic capacity of the autotransformer is calculated according to the following formula:

[0034]

[0035] Where S T is the total capacity of the autotransformer; S C is the electromagnetic capacity of the autotransformer; U2 is the voltage on the medium voltage side of the autotransformer; U1 is the voltage on the high voltage side of the autotransformer.

[0036] Circuit breakers are installed on both the 220kV new energy line 10 and the 35kV new energy line 20.

[0037] The 500kV side equipment of the autotransformer 1 all adopts GIS form and is connected through the reserved bay or newly added bay of the 500kV main bus 5.

[0038] The 220kV side equipment of autotransformer 1 is all in GIS form.

[0039] The switchgear on the 35kV side can adopt prefabricated 35kV box-type switch station or 35kV open-type switchgear combination type.

[0040] The above-mentioned specific implementation methods are used to illustrate the present invention and are only preferred embodiments of the present invention, rather than limiting the present invention. Any modifications, equivalent substitutions, improvements, etc. made to the present invention within the spirit of the present invention and the scope of protection of the claims shall fall within the scope of protection of the present invention.

Claims

1. A main electrical connection system for connecting new energy lines to a hydropower plant, characterized by: The invention comprises an autotransformer (1), wherein the autotransformer (1) is respectively connected to a 500kV branch busbar (2), a 220kV branch busbar (6), and a 35kV branch busbar (12); the 500kV branch busbar (2) is connected to a 500kV main busbar (5); the 220kV branch busbar (6) is connected to a 220kV main busbar (8); and at least one 220kV new energy line (10) is provided on the 220kV main busbar (8); The 35kV branch bus (12) is connected to the 35kV main bus (14), and at least one 35kV new energy line (20) is provided on the 35kV main bus (14). The 220kV side and 35kV side lines of the autotransformer (1) are boosted and integrated and then connected to the 500kV main bus (5), and are connected to the power grid through the 500kV transmission line (22) of the hydropower station.

2. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: A detachable break (23) is reserved on the 220kV branch busbar (6), and a reserved interval for a 220kV circuit breaker (7) is provided between the detachable break (23) and the 220kV main busbar (8).

3. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: The 500kV GIS branch busbar (2) is provided with a 500kV lightning arrester (3) and a 500kV circuit breaker (4).

4. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: The 35kV branch busbar (12) is provided with a 35kV lightning arrester (13) and a 35kV circuit breaker (15).

5. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: The 220kV main busbar (8) is provided with a 220kV busbar voltage transformer and lightning arrester assembly (9).

6. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: The 35kV main busbar (14) is provided with a 35kV busbar voltage transformer and lightning arrester combination (16).

7. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 is characterized by: The 35kV main busbar (14) is provided with an SVG reactive power compensation device (18) and a capacitor bank (19).

8. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1 or 7, characterized in that: A 35kV feeder circuit breaker (17) is provided between the 35kV main busbar (14) and the SVG reactive power compensation device (18).

9. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1, characterized in that: The third winding (35kV side winding capacity) of the autotransformer (1) is controlled to be no less than 35% of the autotransformer electromagnetic capacity to compensate for the third harmonic current. The autotransformer electromagnetic capacity is calculated according to the following formula: Where S T is the total capacity of the autotransformer; S C is the electromagnetic capacity of the autotransformer; U2 is the voltage on the medium voltage side of the autotransformer; U1 is the voltage on the high voltage side of the autotransformer.

10. The main electrical connection system for connecting new energy lines to a hydropower plant according to claim 1, characterized in that: The 220kV new energy line (10) and the 35kV new energy line (20) are both provided with circuit breakers.

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