What are the main components and principles of hydropower plants? Next, Zhong Da Consulting Bidding Teacher will answer your questions for your reference.

First, the basic principle of hydropower, the basic principle of hydropower

Hydroelectric power generation is to use water power (with water head) to drive hydraulic machinery (water turbine) to rotate and convert water energy into rotating mechanical energy. If another machine (generator) is connected to the turbine, it can generate electricity with the rotation of the turbine, and then convert mechanical energy into electrical energy.

In a sense, hydropower is a process in which the potential energy of water is transformed into rotational mechanical energy and then into electrical energy. According to the principle, the output formula of hydropower generation can be calculated as follows: P=9.8 1ηHQ.

P: Output unit: kW power transmitted by the machine end of the unit.

H: Head unit: m (meter) is the effective head acting on the turbine, which is equal to the difference between the water level of the reservoir and the downstream water level (i.e. the gross head) minus the head loss of the diversion part. The head loss is △ H, which is generally 3%~ 10% of Hg (gross head) according to experience, and the water conveyance channel is short.

Q: Flow unit: cubic meter per second (m3/s). Rated flow of hydraulic turbine in hydropower station.

η: Efficiency of hydro-generator set, including efficiency of hydro-turbine and generator. η is not only related to the types and parameters of turbines and generators, but also varies with the operating conditions of units, and is not a constant value. To simplify the calculation, let k=9.8 1η, and the output formula can be simplified as: P= kHQ.

K: output coefficient of hydropower station. K = 8.0 ~ 8.5 for large and medium-sized hydropower stations, 6.5 ~ 8.0 for small and medium-sized hydropower stations and k=6.0~6.5 for small power plants.

Generally, hydropower stations with an installed capacity of less than 500,000 kilowatts are designated as small hydropower stations; those with an installed capacity of 5,000 to 6,543.8+10,000 kilowatts are medium-sized hydropower stations; those with an installed capacity of 6,543.8+10,000 kilowatts are large hydropower stations; and those with an installed capacity of more than 6,543.8+10,000 kilowatts are giant hydropower stations.

Second, the role of hydropower plants in the power system

In the power system, power plants generally include thermal power plants, hydropower plants, nuclear power plants, wind farms, solar power plants and so on. In areas with poor water resources, thermal power plants account for a large proportion, while in areas with rich water resources and high development level, hydropower stations account for a large proportion. Wind farms and solar energy are new energy sources, which have developed rapidly in recent years. The main functions of hydropower plants in the power system are as follows:

(1) provides power. The main tasks of hydropower plants are.

(2) Peak shaving. Major hydropower plants with regulating capacity.

(3) frequency modulation. The large unit with reservoir has strong regulation ability, and the frequency in China is 50±0.2hz.

(4) Phase modulation. Have the ability of phase modulation operation, and can participate in reactive power balance of the system according to the requirements of the power grid.

(5) as an accident standby. Because the hydro-generator set has the characteristics of quick start and grid-connected power generation, when the power system suddenly has an accident, it is in urgent need of supplementary power, and the hydro-generator set is often used as an emergency standby unit.

(6) Energy storage. Pumped storage hydropower plant uses pumped storage in low valley and generates electricity to supply power to the system in peak power consumption to meet the load demand.

Hydropower belongs to clean energy. According to the characteristics of hydropower and its role in the power system, its operation mode generally follows the following principles:

1. Make full use of hydropower. Generally, those with no regulating ability operate as base load, mainly runoff power plants; Generally speaking, in the dry season with adjustable capacity, they participate in peak shaving operation. In the wet season, in order to avoid abandoning water, peak shaving operation is gradually transferred to base load operation, and the peak shaving task is handed over to thermal power plants.

2. In order to reduce the coal consumption of thermal power plants and save resources, hydropower plants participate in peak-shaving operation in dry season, so that thermal power plants can operate in high-efficiency areas. During the wet season, the hydropower plant operates in the base load, and the thermal power plant participates in the peak shaving operation to the maximum extent, so as to minimize water abandonment.

3. Reasonably distribute the load, so that the hydropower unit can run in the high-efficiency area as much as possible. Hydropower units generally avoid operating in low-head and low-load areas. When operating in low-head and low-load areas, it is not only inefficient, but also may operate in vibration areas, which will affect the safe operation and service life of the unit.

Three. Composition and function of hydropower station

Hydropower stations are generally mainly composed of water retaining structures (dams), flood discharge structures (spillways or sluices), water diversion structures (water diversion channels or tunnels, including surge shafts) and power station structures (including tailrace and booster stations).

The main components are: hydraulic structures, hydraulic machinery equipment, power generation equipment, substation equipment, power distribution equipment, power transmission equipment and control and auxiliary equipment.

1. Composition of hydraulic structures Water retaining structure-dam

Discharge structures-spillway, spillway, spillway dam and spillway tunnel gate-intake gate, tailrace gate and spillway gate.

Water-using structures-water intake and diversion structures (channels or tunnels, pressure pipes, water intakes) and hydropower plant 2. Functions of hydraulic structures.

The function of the dam is to intercept the water flow, raise the water level, form a reservoir, cause the water level difference between upstream and downstream, and make the power station have the basic conditions for hydropower generation. On the dam-type hydropower station that regulates the storage capacity, the dam can simultaneously realize the dual functions of concentrating the river head and regulating the flow in the river, which not only serves the hydropower station, but also has the functions of flood control, irrigation, shipping and industrial water supply.

Spillways and spillways are used to release floods, prevent floods from overflowing the roof and ensure the safety of the dam, so they are also called flood discharge structures. Some drainage structures can also be used to empty reservoirs or transfer water during construction. Drainage structures can be divided into spillway and deep drainage channel according to the way of drainage. The function of the gate is to regulate the flow and control the flood. Gates can be divided into low-head gates and high-head gates according to their positions. The power intake gate and the bottom outlet gate belong to high-head gates, and the spillway gate belongs to low-head gates. Judging from its structural division, the most common ones are flat gate and arc gate.

The tailgate is mainly used for equipment maintenance.

Function of water-using structure: It can be divided into water intake and water diversion structure, including water intake and water diversion channel, and its function is to lead the water in the dam to the water-supplying hydro-generator set of the plant for use.

Water diversion channels can be divided into channels, tunnels (with and without pressure), pressure pipes, aqueducts and inverted siphons. Some diversion hydropower stations also have pressure forebay, surge chamber or surge shaft on the diversion structure.

Main workshop: the workshop where the hydro-generator set and its auxiliary equipment are installed, and the assembly site where the generator set is assembled and overhauled.

Auxiliary workshop: workshop for installing distribution equipment and its operation and management facilities. Auxiliary power houses generally include rooms for operation, control, test and management of hydropower stations, as well as rooms for working and living of operators.

1. Composition of hydraulic machinery and equipment: main valve, draft tube of turbine guide bearing.

2. Main valve of hydraulic machinery equipment: in case of accident, cut off the water flow urgently to prevent the unit from escaping; When the unit is overhauled, cut off the water flow; When parking for a long time, close the butterfly valve to reduce water leakage and save water resources.

Hydraulic turbine: according to the installation method, it can be divided into vertical and horizontal; According to the characteristics of energy conversion of water flow, it can be divided into reactive type (using kinetic energy and potential energy of water flow) and impact type (using kinetic energy of water flow only).

Reactive type: axial flow (sizing: h: 3 ~ 50m, turning: h: 3 ~ 80m), mixed flow (H=30~700 m), oblique flow (H=40~200m) and tubular flow (2 ~ 30m).

Impulse type: suitable for small units with high head and small flow, bucket turbine (tangential type) (40 ~ 2,000m, with common head range of 40~800m), diagonal turbine (50~400m) and double-click turbine (6~ 150m).

Components and functions of hydraulic turbines

Volute: forming hydraulic circulation.

Seat ring: bear the full weight of the device.

Bottom ring and top cover: the movable guide vanes are fixed to form the runner chamber.

Runner: Water energy is converted into rotating mechanical energy.

Movable guide vane: control water flow to achieve the purpose of adjusting speed and output.

Shaft: transmits mechanical energy.

Guide bearing: bear radial water thrust and control swing.

Draft tube: Recover energy and output water flow.

(3) Components and functions of the generator

1. Main parts of generator

Stator, rotor, thrust bearing, guide bearing, shaft, frame, cooler and brake.

2. The role of the main parts of the generator

Stator: generates induced potential.

Rotor: produces a rotating magnetic field.

Thrust bearing: it bears the axial water thrust and the self-weight of the rotating parts of the unit.

Guide bearing: bear radial water thrust and control swing.

Shaft: transmits mechanical energy.

Upper frame: Install thrust bearing, upper guide bearing and slip ring.

Lower frame: Install lower guide bearing and brake.

Cooler: The bearing cooler is used to cool the bearing and the air cooler is used to cool the generator.

Braking: Brake the generator when stopping to prevent the thrust bearing from being damaged due to long-term low-speed rotation. (4) Composition and function of substation equipment 1. Composition of substation equipment

Oil-immersed transformer: base, bell jar, oil storage tank, iron core, winding, radiator, etc. Dry-type transformer: iron core, winding, box, radiator, etc. 2. The role of substation equipment

Transformer: Increase or decrease the AC voltage. 1. The power distribution equipment mainly includes: circuit breakers (switches), disconnectors (knives), transformers, lightning arresters, buses, wires, etc.

2. The function of power distribution equipment circuit breaker (switch): to close, carry and break the normal current and overload current of the operation loop. Disconnector (breaker): it carries normal loop current and overload current when closing, and meets the insulation distance when opening, with obvious signs of disconnection. (V) Composition and function of voltage transformer (PT) of distribution equipment: reduce high voltage to the standard voltage of protection, metering, instrumentation and other devices. The general standard voltage is100V.

Current transformer (CT): reduce the large current to the standard current of protection, measurement, instrument and other devices. The general standard current is 5A or1a.

Lightning arrester: electrical equipment for limiting overvoltage protection. Bus: Collect, distribute and transmit electric energy.

Conductor: transmit electric energy. (6) Composition and function of transmission equipment 1. Composition of transmission equipment

Lines, iron towers (poles), lightning wires, etc. 2. Function line of transmission equipment: transmission of electric energy. Iron tower (pole): fixed conductor and lightning rod. Lightning rod: protection of overhead transmission lines (7), composition and function of control equipment 1. The control equipment mainly includes:

Excitation device, speed regulating device, relay protection, synchronization device, automatic device, computer monitoring system, DC system, etc.

2. The role of control equipment

Excitation device: provide direct current for generator rotor to establish magnetic field, control generator terminal voltage or adjust reactive power of unit.

Speed regulating device: control the rotating speed of the unit or adjust the active power of the unit.

Relay protection: Monitor the normal operation of the power system, and when the protected components fail, automatically and quickly issue a trip command selectively, cut off the faulty equipment from the system, ensure the normal equipment to continue to operate, limit accidents to a minimum, improve the reliability of system operation, and ensure the safe and continuous power supply to users to the maximum extent.

Synchronization device: synchronization between different power sources. Type: self-synchronization, quasi-synchronization (automatic quasi-synchronization, manual quasi-synchronization, quasi-synchronization with lights off).

Automatic device: An automatic device that performs certain functions. Type: reclosing device, low-cycle starting device, high-frequency cutting machine device.

Computer monitoring system: through the collection and processing of various equipment information in the power station, the functions of automatic monitoring, control, adjustment and protection can be realized, so as to ensure the safe and stable operation of the equipment, optimize the operation according to the requirements of the power system, make full use of the water energy reasonably, ensure the power quality, reduce the operation and maintenance cost, improve the operation conditions, and realize unattended or less unattended operation. Hardware includes workstation, server, network equipment, GPS clock, UPS power supply, local LCU, data acquisition equipment and communication equipment.

DC system: provides reliable energy for the operation of switchgear and secondary equipment. The DC system consists of storage battery, charging device and power distribution device.

(8), the composition and function of auxiliary equipment

1. Composition of auxiliary equipment of hydropower plant:

Water system: technical water supply, leakage drainage and maintenance drainage.

Oil system: insulating oil and lubricating oil.

Gas system: high pressure gas, medium pressure gas and low pressure gas.

2. The role of auxiliary equipment of hydropower plant

Technical water supply system:

Main objects: generator air cooler, generator thrust bearing and guide bearing cooler, turbine guide bearing cooler, main shaft seal, water-cooled transformer, water-cooled air compressor, lubricating water for deep well pump, fire water, etc.

Sources of technical water supply: upstream reservoir (pressure pipeline or volute, intake in front of dam), downstream reservoir, groundwater source, etc.

Technical water supply methods: gravity water supply, water pump water supply, mixed water supply and jet pump water supply.

Drainage system: prevent water and moisture in the plant and ensure the maintenance of the overflow part of the unit and the underwater part of the plant. Including production drainage, maintenance drainage, leakage drainage and factory drainage.

Oil system:

Lubricating oil: turbine oil, air compressor oil, engine oil and grease, etc.

The function of lubricating oil: lubrication, heat dissipation and energy transfer.

Insulating oil: transformer oil, cable oil and switch oil.

The function of insulating oil: insulation, heat dissipation and arc extinguishing.

Gas system:

High-pressure gas system: supplying gas to the pressure tank of the oil pressure device.

Medium-pressure air system: water guide bearing maintenance sealing belt, butterfly valve water stop belt.

Low pressure gas system: unit shutdown and braking, phase modulation and water pressure, pneumatic tools and purge gas.

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