Amayo in Operations

Electrical Substation

The Amayo Electrical Substation was built to collect the energy from the turbines and send this energy to the grid. It is connect to the high voltage transmission line 230KV near to the border between Nicaragua and Costa Rica countries.

The substation consists of a double bar that lodges to both lines of transmission and elements such as Switches of Power, Surge Arresters, Potential & Current Transformer, etc. A line is from Costa Rica and other one is from Nicaragua.

The Amayo Plant is connecting to the double bars and generates its clean energy towards the line of Nicaragua. All the components are modern to a 230KV; the operations of the components on the Transmission Lines of Nicaragua and Costa Rica are executed by ENATREL-CNDC's personnel.
The protection system consists of Multifunctional Electrical Relays that monitors the power and voltage of generation and transmission of the energy.
The electrical substation is under constant observation for a person of the Operations Department with has a system of monitoring and control (SCADA), all the alarms are presented a Control Room.

General description of the Suzlon S88-2.1 MW

The SUZLON S88-2.1 MW is a variable slip wind turbine with an electrical pitch system that has been designed in accordance with Germanischer Lloyd GLIIa Type Certification. It has a rated power of 2.1 MW, a standard rotor height of 80 metres and a rotor diameter of 88
metres. The power output is controlled by two different systems working together:
» The SUZLON FLEXISLIP SYSTEM (SFS)
» The PITCH SYSTEM.
The SUZLON S88-2.1 MW is designed to withstand harsh environmental conditions. Its robust design and uniform weight distribution ensure high levels of safety, reliability and enhanced Energy yields throughout its lifespan.
The main parts of the Suzlon S88-2.1 MW are the nacelle, the tower and the rotor with the blades. All parts have been designed in line with approved industry standards to guarantee operational safety and efficient operation.
The major components and features of the SUZLON S88-2.1 MW are described in this document.

Hub

The SUZLON S88-2.1 MW rotor consists of a high strength cast iron hub supporting three pitchable rotor blades. The blades are connected to the hub via roller bearings and can be adjusted with the help of the pitch system. It consists of electrical drives with battery backup and it is linked to the control system. With this pitch system it is possible to turn the rotor blades approximately 90°. The rotor hub is directly connected to the main shaft and transmits the torque of the rotor via the drive train to the generator. The hub is housed in a nose cone made of glass-fiber reinforced plastic (GRP).

The rotor blades are made of high grade GRP and manufactured by using Resin Infusing Moulding (RIM) technology. The blades are lightweight but at the same time possess a high degree of stiffness and mechanical strength. Their low weight-todiameter ratio results in lower stresses on the drive train, thus, enhancing the life and efficiency of the turbine.

Pitch System

The pitch angle of each blade is accurately adjusted to the requirements of the control and/or safety system. The pitch system has been designed with a triple redundancy, which means that each blade has its own drive system consisting of a motor, a gearbox and a converter.
Additionally the control system of the entire wind turbine has its own back up system. The pitch drives are directly fastened inside the hub. Their drive pinions are interlocked with the inner gear wheel of the blade bearings, which support the rotor blades. The motors are equipped with an internal brake which holds the blades between the pitching processes. To guarantee high performance the blade bearings are made of high tensile double-row ball-bearing slewing rings.

Generator

The SUZLON S88-2.1 MW has a single-fed asynchronous three-phase generator. During production, the stator side of the generator is permanently connected to the grid. On the rotor side a slip ring connects the generator to the SUZLON FLEXISLIP SYSTEM to obtain a wide slip range.
The generator is kept at optimum operational temperature by a robust air cooling system.

Brake system

The brake system that stops the rotation of the wind turbine consists of two systems:
• The aerodynamic brake, operated by the pitch system of the three blades, stops the turbine almost completely. It is used as the standard brake during automatic operation.
• With the mechanical brake it is possible to stop the idling turbine completely. This brake is for maintenance purposes only.

Wind measurement

The wind measurement equipment is mounted on top of the nacelle roof. It consists of two anemometers and two wind vanes fitted to the wind measurement pole. The sensors are surrounded by a metal rod to protect them against electromagnetic fields due to electrically charged clouds or during thunder storms. The sensors are equipped with heaters.
The control system only works with one of the anemometers and the wind vanes. It permanently tests for plausibility and chooses the correct working sensor.

Control system

The SUZLON S88-2.1 MW operates with SC-Turbine® which is a part of the SUZLON® Control System (SCS)®. A robust industrial PLC (Programmable Logic Controller) monitors values and status signals of the wind turbine sensors, as well as all measured values and status of the signals that influence the operating process, according to the electrical and mechanical engineering requirements that set the upper and lower limits.
If the limit of a monitored value is exceeded, a visual warning is displayed and the relevant brake or yaw programmes activated.
Furthermore, the turbine has two systems for speed and power regulation working side by side.
These are the pitch control system and the SUZLON Flexislip System (SFS).
a.- The rotational speed is controlled by the pitch system by changing the blade angle. At low winds, the pitch angle is set to an optimum value to reach the nominal rotational speed and the optimal power output as soon as possible. At higher wind speeds, the blades are moved to retain the nominal rotational speed even during gusts.
b.- The SFS controls the rotor current and thus the power output at higher wind speeds to keep the nominal power constant. It also reduces the mechanical loads on the turbine during cut-in and gusts.

Grid connection

The SUZLON S88-2.1 MW grid connected power system consists of the following components:
- Transformer
- Power cable between tower base and transformer
- Main circuit breaker
- Generator contactor
- Capacitor bank (Reactive power compensation)
- Bypass contactor
- Soft starter (Thyristors)
- Power cables between tower base and generator
- Generator

The turbine starts up by turning the rotor blades to an optimum blade angle, thus accelerating the rotor. When the generator speed has reached synchronous speed, it is connected to the grid via a soft starter controlling the inrush current. After this, the bypass contactor switches on and bypasses the soft starter. The generator is firmly connected to the grid.