Electrical main wiring circuit for pumped storage power station

Abstract

The utility model discloses an electrical main wiring circuit for a pumped storage power station, which belongs to the technical field of pumped storage power stations and comprises a constant-speed generator motor, a variable-speed generator motor, a generator circuit breaker, a phase change isolating switch and a main transformer. The generator motor is connected with the main transformer through the generator circuit breaker and the phase change isolating switch; the starting loop equipment comprises a constant-speed unit static variable-frequency starting device, a dragged isolating switch and a dragging isolating switch; the static frequency conversion starting device is powered by the main transformer and is connected to the generator motor through the dragged isolation switch. The alternating current excitation loop equipment comprises a variable speed unit alternating current excitation device and an overvoltage protection device; a power supply of the AC excitation device is taken from the main transformer and is connected with the variable-speed generator motor. The overvoltage protection device is connected with the AC excitation loop through a branch bus. And the high-voltage side equipment comprises combined unit equipment, a high-voltage cable, a circuit breaker and an overhead outgoing line.

Description

Technical Field

[0001] The utility model belongs to the technical field of pumped storage power stations, in particular to an electrical main wiring circuit for a pumped storage power station. Background Art

[0002] The main electrical equipment of a pumped-storage power station includes generator motors, generator circuit breakers, phase-commutating disconnectors, static variable-frequency starting devices, AC excitation devices, driven disconnectors, driving disconnectors, main transformers, combined unit equipment, high-voltage cables, circuit breakers, overhead lines, and other equipment. These devices together constitute the core system of a pumped-storage power station, ensuring its efficient and stable operation.

[0003] A typical pumped-storage power station typically has four or six generators installed, each with a capacity ranging from 250 MW to 400 MW. There are three main wiring methods for connecting these generators to the transformer bank: unit wiring, combined unit wiring, and expanded unit wiring. Each wiring method has its own unique advantages and applicable scenarios, and the choice can be made based on actual needs and project characteristics.

[0004] Pumped-storage power stations typically connect to the power system at voltage levels of 220kV, 330kV, 500kV, or 750kV. These different voltage levels meet the connection requirements of power systems of varying sizes and needs. High-voltage side wiring options include single busbar, single busbar segmentation, double busbar, bridge, triangle, quadrilateral, and 3 / 2 circuit breaker connections. Each connection method has its own specific application scenarios and advantages, and can be selected based on the specific needs of the power station and the grid structure.

[0005] Currently, there are no operational pumped-storage power plants globally that simultaneously meet the high standards of more than 10 units, including both fixed-speed and variable-speed units, and the flexible dispatch requirements of power systems. This type of plant requires a high degree of flexibility and reliability to adapt to changing power demand and grid operating conditions. In the future, with continued technological advancements and increasing market demand, these high-standard pumped-storage plants are expected to become a reality, providing strong support for the stable and efficient operation of power systems. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide an electrical main connection circuit for a pumped storage power station, which has the characteristics of being safe and reliable, flexible in scheduling, and convenient in operation and maintenance for multiple units, multiple models, multiple starting modes, and multiple inlet and outlet line circuits.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] An electrical main wiring circuit for a pumped storage power station, comprising:

[0009] Generator-transformer equipment, including M fixed-speed generator motors and N variable-speed generator motors; each fixed-speed generator motor is connected to a main transformer via a generator circuit breaker and a set of phase-changing disconnect switches; each variable-speed generator motor is connected in sequence via a generator circuit breaker, a phase-changing disconnect switch, and a main transformer; M and N are both natural numbers greater than 1;

[0010] The starting circuit equipment includes L static variable frequency starting devices for fixed-speed units, M driven disconnect switches, and P driving disconnect switches; the power supply of each static variable frequency starting device is taken from the main transformer and connected to the fixed-speed generator motor through a driven disconnect switch; a fixed-speed generator motor operating as a generator is connected to any other fixed-speed generator motor operating as a motor through a driving disconnect switch and a driven disconnect switch; L is a natural number greater than 1 and less than M;

[0011] AC excitation circuit equipment, including N variable-speed generator set AC excitation devices and N overvoltage protection devices; each AC excitation device is powered by a main transformer and connected to the rotor circuit of the variable-speed generator motor; the overvoltage protection device is connected to the AC excitation circuit via a branch bus;

[0012] The high-voltage side equipment includes Q combined unit devices; the main transformer is connected to the circuit breaker string and the overhead outgoing line respectively through the combined unit devices and high-voltage cables; Q is a natural number greater than 1.

[0013] Preferably, the circuit breaker string includes a 3 / 2 circuit breaker string and a double circuit breaker string.

[0014] Preferably, the fixed-speed generator motor and the variable-speed generator motor are connected to the main transformer via a generator circuit breaker and a phase-changing isolating switch to form a one-machine-one-transformer high-voltage side combined unit connection.

[0015] Preferably, the M constant-speed generator motors are divided into a plurality of constant-speed generator motor groups, and each constant-speed generator motor group adopts a different electric working condition starting method according to the number of constant-speed generator motors (5).

[0016] Preferably, when the number of constant-speed generator motors in each constant-speed generator motor group is greater than or equal to 6, two sets of static frequency conversion starting devices are used as backup for each other; when the number of constant-speed generator motors in each constant-speed generator motor group is less than or equal to 4, one set of static frequency conversion starting device is used as the main starting device, and back-to-back starting is used as the backup starting method.

[0017] Preferably, there are two variable speed generator motors.

[0018] The beneficial effects of the utility model are:

[0019] By adopting the above-mentioned technical solution, the electrical main connection circuit for the pumped storage power station disclosed by the utility model can fully meet the technical requirements of multiple units, multiple models, multiple starting methods and multiple input and output line circuits. This technical solution not only has high reliability, but also has the technical advantage of flexible scheduling. Specifically, the utility model takes into account the simultaneous access of multiple large-capacity constant-speed generator motors and variable-speed generator motors, so that the power station can operate more reliably and be more flexible in scheduling. In addition, the utility model also solves an important problem facing the power system, that is, how to take into account wind power, photovoltaic regulation and the isolated grid operation of the power station. Through the technical solution of the utility model, the power station can maintain high efficiency and stability under various operating modes, thereby providing strong technical support for the stability and reliability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a circuit diagram of a preferred embodiment of the present utility model.

[0021] In the figure: 1. Generator-transformer group equipment; 2. Starting circuit equipment; 3. AC excitation circuit equipment; 4. High-voltage side equipment; 5. Fixed-speed generator motor; 6. Variable-speed generator motor; 7. Generator circuit breaker; 8. Phase-changing disconnector; 9. Main transformer; 10. Static variable-frequency starting device for fixed-speed units; 11. AC excitation device for variable-speed units; 12. Driven disconnector; 13. Driving disconnector; 14. Combined unit equipment; 15. High-voltage cable; 16. Overhead outgoing line; 17. 3 / 2 circuit breaker string; 18. Double circuit breaker string; 19. Busbar section circuit breaker; 20. Overvoltage protection device. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0023] like Figure 1 As shown,

[0024] An electrical main wiring circuit for a pumped storage power station mainly includes:

[0025] The generator-transformer group device 1 includes M fixed-speed generator motors 5 and N variable-speed generator motors 6; each fixed-speed generator motor 5 is connected to a main transformer 9 via a generator circuit breaker 7; each variable-speed generator motor 6 is connected in sequence via a generator circuit breaker 7, a phase-changing disconnector 8, and a main transformer 9; M and N are both natural numbers greater than 1;

[0026] The starting circuit device 2 includes L static variable frequency starting devices 10 for constant speed units, M driven isolating switches 12, and P driving isolating switches 13; each static variable frequency starting device 10 is powered by a main transformer and connected to a constant speed generator motor 5 via a driven isolating switch 12; a certain constant speed generator motor 5 operating as a generator is connected to any other constant speed generator motor 5 operating as a motor via a driving isolating switch 13 and a driven isolating switch 12; L is a natural number greater than 1 and less than M.

[0027] AC excitation circuit equipment 3, including N variable-speed unit AC excitation devices 11 and N overvoltage protection devices 20; each AC excitation device 11 is powered by a main transformer 9 and connected to the rotor circuit of the variable-speed generator motor 6, and the overvoltage protection device 20 is connected to the AC excitation circuit via a branch bus;

[0028] The high-voltage side equipment 4 includes Q combined unit devices 14; the main transformer 9 is connected to the circuit breaker string and the overhead line 16 in sequence through the combined unit devices 14 and the high-voltage cable 15; Q is a natural number greater than 1.

[0029] The circuit breaker strings include two types of circuit breaker strings, namely: a 3 / 2 circuit breaker string 17 and a double circuit breaker string 18 .

[0030] This utility model is designed to meet the diverse needs of the electrical main wiring of pumped storage power stations, especially for complex application scenarios with multiple units, multiple models, multiple starting methods, and multiple input and output circuits. Specifically, the electrical main wiring system can be divided into the following main components:

[0031] The generator-transformer assembly 1 is the core of the entire system. It includes a fixed-speed generator motor 5, a variable-speed generator motor 6, a generator circuit breaker 7, a phase-changing disconnector 8, and a main transformer 9. These devices work together to ensure efficient connection and stable operation between the generator motor and the transformer.

[0032] Secondly, the starting circuit equipment 2 is responsible for providing a reliable starting mechanism. It includes a static variable frequency starting device 10 for the fixed-speed unit, a driven disconnector 12, and a driving disconnector 13. These devices ensure that the fixed-speed generator motor 5 can be reliably started under various operating conditions, thereby meeting the operational requirements of the power station.

[0033] Furthermore, the AC excitation circuit device 3 mainly consists of the variable speed unit AC excitation device 11 and its overvoltage protection device 20. This device can realize the self-starting of the variable speed generator motor 6 under the electric working condition, thereby improving the flexibility and reliability of the system.

[0034] In addition, high-voltage side equipment 4 includes combined unit equipment 14, high-voltage cables 15, overhead outgoing lines 16, 3 / 2 circuit breaker strings 17, double circuit breaker strings 18, and busbar section breakers 19. The rational layout and configuration of these devices not only optimizes the high-voltage side wiring structure, but also reduces the number of incoming line loops and the use of high-voltage cables, thereby improving the economy and reliability of the system.

[0035] Specifically, the fixed-speed generator motor 5 and the variable-speed generator motor 6 are connected to the main transformer 9 via a generator circuit breaker 7 and a phase-changing disconnector 8, forming an efficient one-generator-one-transformer high-voltage side combined unit connection. This design not only simplifies the wiring structure but also improves system operating efficiency.

[0036] Regarding the starting circuit equipment 2, two sets of mutually redundant static variable-frequency starting devices 10 and driven disconnect switches 12 ensure reliable starting of six or more constant-speed generator motors 5 under motoring conditions. Furthermore, one set of static variable-frequency starting devices 10 and driven disconnect switches 12 serves as the main starting device for four constant-speed generator motors 5. While one of these generator motors is operating as a generator, the remaining constant-speed generator motors 5 can be started back-to-back as motors via the generator circuit breaker 7 and the driven disconnect switch 13.

[0037] AC excitation device 11 enables self-starting of variable-speed generator motor 6 in motoring mode, thereby improving system flexibility and reliability. The use of combined unit equipment 14 reduces the number of incoming wiring loops in high-voltage side wiring 4 and the number of high-voltage cables 15. It also optimizes the number of incoming wiring in 3 / 2 circuit breaker strings 17 and dual circuit breaker strings 18, further improving system economy and reliability.

[0038] Overhead outgoing lines 16 effectively connect the pumped-storage power station to the grid, ensuring that electricity can be smoothly fed into the grid during power generation and drawn from the grid during pumping. Furthermore, busbar segmentation circuit breakers 19 enable segmented operation of multiple generator motors, allowing the power station to operate both connected to the AC mains and in isolation from the flexible DC grid.

[0039] In summary, this multi-unit, multi-model, multi-starting mode, and multi-input and output line circuit design for a pumped-storage power station not only fulfills the power station's electrical functions but also boasts a clear and rational structure, high reliability, and flexible dispatching capabilities. It allows for the simultaneous connection of multiple large-capacity fixed-speed and variable-speed generators, facilitating reliable operation and flexible dispatching of the power station. Furthermore, this design addresses issues related to wind power and photovoltaic regulation within the power system, as well as the isolated operation of the power station and the flexible DC grid, providing strong technical support for the stable operation of modern power systems.

[0040] This utility model organically combines the main circuit, starting circuit, and AC excitation circuit of the generator-transformer assembly, enabling flexible connection of fixed-speed and variable-speed generators. It can implement two static variable-frequency starting devices for backup in the fixed-speed generator's electric operation mode, a single static variable-frequency starting device for back-to-back starting, and automatic starting using the AC excitation system for the variable-speed generator's electric operation mode. A 3 / 2 circuit breaker + dual circuit breaker design and busbar segmentation on the high-voltage side facilitate flexible scheduling and operation of multiple units in the power station.

[0041] The following is a further explanation using a large pumped storage power station project that adopts the technical solution of the utility model as an example with reference to the accompanying drawings:

[0042] A large-scale pumped-storage power station project with a total installed capacity of 3600 MW was developed in two phases, with Phases I and II each having an installed capacity of 1800 MW. Phase I installed six 300 MW fixed-speed pump-turbine-generator units, while Phase II installed four 300 MW fixed-speed pump-turbine-generator units and two 300 MW variable-speed pump-turbine-generator units. According to the power system design requirements for the power station's access, the AC side of the converter station must be connected to the local AC grid and capable of islanding with the flexible DC grid via busbar sectionalizers. During islanded operation of the converter station, six units of the pumped-storage power station must be connected to the converter station, while another six units are connected to the local AC grid. The two variable-speed generators must always be connected to the flexible DC grid.

[0043] In order to meet the electrical main wiring design requirements of a pumped-storage power station with multiple units, multiple models, multiple starting modes, and multiple inlet and outlet circuits, the generator motor (including 10 fixed-speed generator motors 5 and 2 variable-speed generator motors 6) transformer group 1 adopts a one-unit-one-transformer high-voltage side combined unit connection. A generator circuit breaker 7 is installed in the generator main circuit to ensure the operation, maintenance, synchronization and scientific acquisition of the plant power supply requirements of the unit; a phase-changing disconnector 8 is installed in the generator main circuit to meet the operating conditions of the pumped-storage power station between power generation and pumping; the generator starting circuit is equipped with two sets of static variable frequency starting devices 10 and a driven disconnector 12, which serve as backup for each other. This ensures reliable electric-mode starting of six or more constant-speed generator motors 5. The generator starting circuit is equipped with a static variable-frequency starting device 10 and a driven disconnector 12, serving as the main electric-mode starting device for the four constant-speed generator motors 5. When one of the four constant-speed generator motors 5 is operating as a generator, the generator breaker 7 and the driven disconnector 13 in this circuit can be used to start the fixed-speed generator motors 5 back-to-back, acting as motors, through the driven disconnector 12 in another circuit. The generator circuit is equipped with an AC excitation device 11 to meet the excitation requirements for both electric-mode starting and normal operation of the variable-speed generator motors 6. The combining unit 14 in the high-voltage side wiring 4 combines the two generator motor-transformer groups on the high-voltage side and then connects them to the 3 / 2 circuit breaker string 17 and the double circuit breaker string 18 via high-voltage cables 15. Overhead outgoing lines 16 and high-voltage cables 15 are routed between the different breakers in the 3 / 2 circuit breaker string 17 and fed into the power system. The busbar section circuit breaker 19 is used to disconnect the busbars on both sides and their ancillary equipment when necessary, so that the two phases of the project can be connected to the AC grid and the flexible DC grid respectively.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electrical main wiring circuit for a pumped storage power station, characterized in that: include: A generator-transformer group device (1) includes M fixed-speed generator motors (5) and N variable-speed generator motors (6); each fixed-speed generator motor (5) is connected to a main transformer (9) via a generator circuit breaker (7) and a set of phase-changing isolating switches (8); each variable-speed generator motor (6) is connected in sequence via a generator circuit breaker (7), a phase-changing isolating switch (8) and a main transformer (9); M and N are both natural numbers greater than 1; A starting circuit device (2) comprises L constant-speed unit static variable frequency starting devices (10), M driven isolating switches (12) and P driving isolating switches (13); the power supply of each static variable frequency starting device (10) is taken from a main transformer and connected to a constant-speed generator motor (5) through a driven isolating switch (12); a constant-speed generator motor (5) operating as a generator is connected to any other constant-speed generator motor (5) operating as a motor through a driving isolating switch (13), a driven isolating switch (12); L is a natural number greater than 1 and less than M; AC excitation circuit equipment (3) includes N variable speed generator set AC excitation devices (11) and N overvoltage protection devices (20); the power supply of each AC excitation device (11) is taken from the main transformer (9) and connected to the rotor circuit of the variable speed generator motor (6); the overvoltage protection device (20) is connected to the AC excitation circuit using a branch bus; The high-voltage side equipment (4) includes Q combined unit devices (14); the main transformer (9) is connected to the circuit breaker string and the overhead outgoing line (16) in sequence through the combined unit devices (14) and the high-voltage cable (15); Q is a natural number greater than 1.

2. The main electrical connection circuit for a pumped storage power station according to claim 1, characterized in that: The circuit breaker strings include a 3 / 2 circuit breaker string (17) and a double circuit breaker string (18).

3. The main electrical connection circuit for a pumped storage power station according to claim 1, characterized in that: The fixed-speed generator motor (5) and the variable-speed generator motor (6) are connected to the main transformer (9) via a generator circuit breaker (7) and a phase-changing isolating switch (8) to form a one-machine-one-transformer high-voltage side combined unit connection.

4. The main electrical connection circuit for a pumped storage power station according to claim 1, characterized in that: The M constant-speed generator motors (5) are divided into a plurality of constant-speed generator motor groups, and each constant-speed generator motor group adopts a different electric working condition starting method according to the number of constant-speed generator motors (5).

5. The main electrical connection circuit for a pumped storage power station according to claim 4, characterized in that: When the number of the constant-speed generator motors (5) in each constant-speed generator motor group is greater than or equal to 6, two sets of static variable-frequency starting devices (10) are used as backup for each other; when the number of the constant-speed generator motors (5) in each constant-speed generator motor group is less than or equal to 4, one set of static variable-frequency starting devices (10) is used as the main starting device, and back-to-back starting is used as the backup starting mode.

6. The main electrical connection circuit for a pumped storage power station according to claim 1, characterized in that: There are two variable speed generator motors (6).

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