We believe in the Power of Nature

Hydropower Project

TOCOMAManuel Piar - Venezuela

The highest capacity and most efficientKaplan generating units in the world

characteristicsTechnical

Electrical systems

Auxiliary service transformers

Isolated phase bus ducts

High and low voltage equipment

Main generator circuit breakers

DC AC supply system

Wiring

Grounding system

Spare parts for all equipment

Turbine model tested at IMPSA's laboratories in Argentina andverified in Lausanne, Switzerland

Customer personnel training

Other equipment and services

Camp and infrastructure for assembly / erection and on-site testing

Assembly / erection, on-site tests and start-up

Name Manuel Piar (Tocoma)

Country Bolivarian Republic of Venezuela

Customer CVG EDELCA

Scope of Supply Water-to-Wire

Installed Capacity 2,350 MW

Mean annual energy 11,900 GWh

Equivalent Energy 68,000 BOED

Projectdescription

The Manuel Piar Project is the last hydropower development of the Bajo Caroní Hydropower Complex. This Complex also includes the Simón Bolívar plant in Guri, Francisco de Miranda plant in Caruachi and the Antonio José de Sucre plant in Macagua. The project is situated approximately 15 km downstream of the Simón Bolívar Hydropower Plant between Río Claro and the Serranías de Terecay.

Works include the construction of a spillway with radial gates and the corresponding closing dams. The powerhouse and the assembly bay are integrated with the intake structure. The location of the civil structures is based on the optimization of geological, topographical and energy conditions. The concrete-faced rock-fill dam (CFRD) is 65 m high and 360 m long.

The powerhouse is equipped with the highest capacity and most efficient Kaplan generating units in the world.

Ancillary systems

Full compressed-air systems at high pressure for the governor

Fire protection system for generators, main transformers andancillary systems

The project will save 25 million barrels of oil equivalent per year, eliminating the corresponding greenhouse gas emissions, thus aiding in the prevention of global warming and environmental pollution.

10 x 235 MW

34.65 m

90 rpm

Kaplan

13.8 kV

60 Hz

10 x 257 MVA

5 x 460 MVA

13.2 kV

400 kV

ODAF

Turbines

Governors

Quantity x Capacity

Rated head

Speed

Type

Type

Generators

Generating voltage

Frequency

Quantity x Capacity

Excitation systems

Type

Power transformers

Quantity x Capacity

Medium voltage side

High voltage side

Type

Type of cooling

Tap changer type

Electro-hydraulic with PID control

Static with electrical brake

Three-phase

No load

Runner diameter 8,600 mm

Guarantee verification tests at the EPFL laboratory

Hydraulic design

The model tested and approved at the EPFL was sent back from Switzerland to Argentina, where it was tested witnessed by

CVG EDELCA´s representatives, verifying compliance with all contract's guarantees.

The turbine's scale model was tested at IMPSA's

Technology Research Center, together with CVG

EDELCA's representatives.

This was the last landmark of a long development process

that included:

? Hydraulic design of the turbine;

? Mechanical design of the scale model;

? Internal tests and changes to meet the project's

performance requirements;

? Preliminary tests with their respective report sent

together with the physical model to the École

Polytechnique Fédéral de Lausanne (EPFL),

Switzerland, one of the world's most important

hydraulic machines laboratories.

It was an enormous technological challenge for

IMPSA to reach the highest competitive behavioral

and performance parameters within the tight

deadline of the bidding process.

Of the five companies pre qualified by the customer

to participate in the bid, among which were the most

important in the world, only three sent models to the

EPFL and only two passed the test successfully:

IMPSA was one of them. The mean weighted

efficiency and the cavitations margins measured

exceeded CVG EDELCA's minimum requirements.

The efficiency measured at Lausanne was the same as

the one measured at IMPSA's laboratory in Mendoza

during the preliminary tests. This once again

consolidates the precision of the measurements

performed at IMPSA's laboratory.

Turbines

Governor

IMPSA's governor is of the digital electro-hydraulic type with PID control. The control electronics, composed of standard

high-quality PLCs, is highly reliable and facilitates maintenance. The control architecture consists of redundant controllers in

hot-stand by configuration. This ensures high fault tolerance in the case of a controller failure, preventing the generating unit

from shutting down, otherwise, the load would be rejected and the power system would be adversely affected.

The software includes speed, power, position, and 3D-CAM control functions required for this kind of unit.

The pressure oil system (air/oil) has a pumping unit with four screw-type pumps to pressurize the system and two pressure

vessels at 63 bar (one air/oil tank and one air tank) with an accumulated volume of approximately 30,000 liters.

Electrical balance of plantThe supply comprised:

Five power transformers with their associated equipment, including surge arresters, fire protection systems and oil

purification equipment.

Electrical interconnection between generators and transformers at generating voltage is done with ten three-phase

isolated phase bus ducts. Protection and maneuver of the AC generators is done with ten circuit breakers and ten

disconnecting switches.

Power supply system for the auxiliary electrical services in the powerhouse and in the spillway. It consists on main

boards, non-segregated bus ducts, distribution boards, fuse disconnecting switches and cabinets, three-phase

transformers and two emergency diesel generating systems.

Mechanical Design

The vertical shaft Kaplan turbines have steel draft tubes

embedded in concrete and concrete semi spiral cases.

The design allows to disassemble all components mounted on

the upper cover (guide bearing, distribution mechanism and

shaft seal), without dismounting the rotor.

The runner is equipped with adjustable blades mounted on

bronze bushings in a cast steel hub. These blades are cast steel

with high mechanical and cavitations resistance. Then they are

machined in a simultaneous 6-axis computer numeric control

(CNC) center and, finally, they are ground by hand. The blades

are rotated by the regulation mechanism, which is directed by

four servomotors and equipped with an emergency closing

system.

The support of the combined bearing consists of a welded steel

plate cone flanged at both ends. This rigid structure transmits

stresses from the thrust bearing to the turbine cover.

Generators

Excitation system

This machine converts the turbine's mechanical energy into electricity for transmission to consumption centers.

Hydro generators are three-phase, vertical shaft, salient-pole synchronous machines, each with a capacity of 257 MVA.

Integral dimensioning of the generator was performed with IMPSA's own ARGEN expert system, which analyze the

equipment's behavior, both in steady and transient states as well as under normal and fault conditions. This software simulates

all the issues required to produce this type of machine: components' dimensioning, electromagnetism, electrical and magnetic

circuits, fluid mechanics and heat transmission, strength and fatigue of materials, tribology, shaft-line stability, vibrations and

oscillatory behavior.

3D Computer Aided Design (CAD) was used throughout the whole design process. Verification operations were carried out

not only with tools developed by IMPSA and integrated into the PROGEN expert system, but also with applications that use

finite element analysis.

The Tocoma stator inner diameter is 12.65 m and core length is 2.05 m long. The rotor consists of a welded spider and a rotor

rim made up of stacked segments for asymmetric radial ventilation, with the rotor generating pressure for machine cooling.

Automatic Voltage Regulation (AVR): It consists of an automated system with a processing unit in redundant

configuration (hot-stand by) and of field current controllers for each rectifying bridge SCR (thyristor). In the event at

of internal failure, this configuration perform either processing unit or power stage conmutation.

Power stage: It is made up of two rectifying bridges, one of them in cold stand-by to ensure double power

redundancy without jeopardizing the other SCRs in the event of a power failure near the rectifiers.

Field discharge: In the event of an operative normal shutdown, the system performs an electronic de-excitation

without opening the field circuit breaker, thus extending its service life. In case of an electrical blockage, the field

breaker opens quickly, releasing the rotor energy in a non-linear resistor.

Excitation transformer: Dry-type cast resin transformer. Current transformers on both the primary and secondary

sides, permit the use of a differential protection. The secondary side is equipped with a fuse-switch to disconnect the

rectifying stage and the generator.

The system includes:

This project is yet another example of IMPSA's commitment to providing integrated solutions

for renewable power generation.

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