PowerPoint Presentation

HYDROELECTRIC POWER PLANT. 20EE0307 DPSC PATHIRANA.

HYDROPOWER GENERATION IN SRI LANKA. Hydro Power Generation Laxapana Complex 378.3 MW Total Mahaweli Complex 816 MW Total Samanala Complex 211 MW Total.

Basic Structure Of A Hydro Power Station. Diagram of a hydro electric power system.

Water is the main source of hydropower .Therefore, the water is temporarily stored in a Reservoir and kept at a high potential before it is taken to the power plant. This stored water flows through a Tunnel to the power plant below it. In this process, potential energy of water convert into high kinetic energy..

A Penstock is a sluice or gate that controls the flow of water, typically in hydroelectric power plants or water distribution systems. It is a crucial component for regulating water flow and managing pressure in these systems. The Surge Tank provides protection to the penstock against damage of water hammer. After the penstocks water comes to the Turbine and turbine is activated due to the high kinetic energy of water. Due to this interaction of the turbine, the Generator produces electricity. A Switchyard in a power plant is an area where electricity generated within the plant is transferred, controlled, and distributed. It typically includes switches, circuit breakers, transformers, and other equipment to manage the flow of electricity from the generators to the transmission or distribution system. The switchyard plays a crucial role in ensuring the safe and efficient distribution of power produced by the plant..

Francis Turbines Suitable for medium to high head applications, Francis turbines are versatile and widely used These turbines operate at the water head ranged from 40 to 600 m Francis turbine is the fact that water changes direction as it passes through the turbine. The flow enters the turbine in a radial direction, flowing towards its axis, but after striking and interacting with the turbine blades it exits along the direction of that axis In order for it to operate efficiently, water must reach all blades equally and flow is controlled by a casing which curls around the turbine in a spiral shape Wimalasurendra power station has this type of turbine.

Pelton Turbines Ideal for high head, low-flow conditions, Pelton turbines use jets of water to generate power. In this type of turbine, high speed jets of water emerge from the nozzles that surround the turbine These nozzles are arranged so the water jet will hit the buckets at splitters, the center of the bucket where the water jet is divided into two streams Following the bucket's inner curve, the two distinct streams exit in the opposite direction from which they entered. Due to the water's altered momentum, the turbine's blades experience an impulse that causes the turbine to rotate and produce torque ..

In lakxapana power station has Pelton type turbines. Old lakxapan has horizontal Axis peloton turbines with two nozzle. New lakxapan has vertical Axis peloton turbines with four nozzle. ..

Turbine Rated Power 50 MW Turbine Type Vertical Axis Pelton Speed 428.5 rpm Effective Head 1,775 ft. No. of Nozzles 4 Rated Discharge 11.5 Cumecs Generator Rated MVA 72,000 kVA Rated P.F. 0.8 Terminal Voltage 12.5 kV Synchronized at 132 kV Excitation Brushless.

EXITATION SYSTEM 1) Static Excitation system In the static excitation system, the rotating rectifier is not being used. The supply to the rotor field is being given through the brushes which are static. In this system, the AC power is tapped off from the generator terminal stepped down and rectified by fully controlled thyristor Bridges and then directly fed to the field of the main generator through slip rings thereby controlling the generator voltage output. Excitation transformer is the power source for static excitation system. AC power from the excitation transformer is converted to DC power for providing excitation to the generator filed windings..

2). Brushless Excitation System AVR is an electronic device that maintains a constant voltage level to electrical equipment on the same load. AVR provide Dc supply to stator. Due to this Dc supply, an AC voltage induced in stator and this AC supply will be converted into DC supply by rotating diodes The generator will be provided this DC supply. Due to this DC supply, a 3 phase Ac current is induced at generator..

GOVERNOR SYSTEM Governor refers to a device or system that regulates the speed or output of a hydroelectric turbine to maintain a stable and controlled operation. To start, maintain and adjust unit speed for synchronizing with the running units/grid. To maintain system frequency after synchronization by adjusting turbine output to load changes. To share load changes with the other units in a planned manner in response to system frequency error. To adjust output of the unit in response to operator or other supervisory commands. To perform normal shut down or emergency over speed shut down for protection The governor controls the inflows into the turbines based on the demand of the electrical load. It senses the rotational speed (RPM) of the turbine and changes the flow into the turbines such that RPM remains constant. An increase in RPM denotes an underloading of the turbine and results in the governor restricting the flow to the turbine..

FREQUENCY CONTROL In Sri Lanka, Frequency of Power supply is about 50Hz. Normally electricity is generated according to the demand of consumers . Demand = Generation If Demand > Generation , must supply more electricity to system. Generators work most speedily, and frequency goes high above 50Hz If Demand < Generation . Generators work most slowly, and frequency goes low below 50Hz. Therefore, we must control frequency of power supply approx. 50Hz. For that a few hydropower plats are kept, and they are used to frequency control. ( Kotmale, Samanala wewa, Victoria…). The necessary instructions are given by frequency control center and accordingly the respective power plants increase or decrease their generation automatically. It is called Automatic Load Frequency Control (ALFC) . In Failure of power system, generator can keep the system at few time without breaking. Generator provide their inertia ( Reactive power) to system. But when the system can't keep anymore the machines automatically turn off for the safety.

[image] HYDRO RESERVOIR COMPLEX KEHELGAMU OYA TIEREAGH S. -12.66 LAXAPANA COMPLEX MAUSSAKELLE RE -12.03m ASKELIYA OYA WIMALASURENDRA ps NEW LAXAPANAP NORTON PON -4.7ft KEHELGAMU WEI KOTMALE OYA CANYON POND -10.9ft OLD LAX-APANA PS POLA TYAPS LAXAPANA POND -11.4ft BROADLANDS POND BROADLANDS ps KELANI RIVER.

According to the water priority, full capacity of water can not used to generate electricity. Therefore, water must manage for using. The highest power station releases water to its pond, after energy production. This water is used below power station for energy production. Therefore, highest power station has a responsibility to release sufficient water to the pond . Thus, all power plants must maintain their ponds at the appropriate water level and notify the authorities. It called pond balancing. During the rainy season, some reservoirs may spill ,as the water in the watercourses increases. Therefore, power plants produce energy at maximum capacity during these times without wasting water. In the same way, during periods of without rain, hydropower station produce electricity that only the amount of power required by the system and when the water level in the reservoirs is very low, the respective turbines are shut down. As well as several power stations are installed in the same riverbank and more electricity is generated. ..

MAINTAINES OF HYDRO POWER PLANT Turbine Maintenance: Regular inspection and cleaning of turbines vibration analysis temperature monitoring oil analysis visual inspections Generator Maintenance: Checking and servicing generators for optimal performance, including inspecting electrical components and connections. Oil and Lubrication Checks: Regularly inspecting and changing oils and lubricants in various components to prevent wear and tear Control System Maintenance: Ensuring the proper functioning of control systems, which regulate water flow and electricity generation. Penstock Inspection: Periodic checks of the penstock, the pipe carrying water to the turbines, to detect and repair any leaks or corrosion.

A large dam with water falling from it. END.