Page 276 - Fluid Power Engineering

Deploying W i nd T urbines in Grid 243

IEC 61400-25 21 provides a standard for the information model, infor-
mation exchange, and mapping to communication profile.
The main functions of a SCADA system are: Data acquisition,
reporting, and control.

Data Acquisition
The SCADA system is the main repository of all the data. All this real-
time data is collected and stored in a database and, as expected, the
volume of this data is enormous. For convenience, the data types are
classified into four types:
Energy Production Data
Data about energy production by each turbine and energy availability
at critical collection points and substation are measured and sent to
the SCADA system.
Events and Availability Data
Events are change in status of turbines, switchgears, met-towers, sub-
station, and SCADA system itself. These events along with grid events
are classified, time stamped, and recorded.
Machine Condition Data
Turbines report condition data that includes temperature of fluids,
acoustic emission, vibration, strain gauge readings, and any other
form of data that the turbine manufacturer uses to monitor the condi-
tion and predict impending failure. The trend is toward use of embed-
ded sensors in structural elements, like blades and towers, in order
to monitor changes in structural dynamics of these components. This
data is used by O&M for routine and unscheduled maintenance.

Wind Measurement Data
Each turbine is equipped with meteorological sensors. In addition,
permanent met-towers are installed to independently measure wind
data and other weather parameters. This data is used to compare
actual versus predicted power curve, actual versus predicted energy
generation, and others. The SCADA system collects and records this
data.

Reporting
The real-time data collected by the data acquisition system is impossi-
ble to examine and analyze because of the volume of data. Therefore,
SCADA provides various aggregates of data and report templates to
support various entities like operations, maintenance, and business
departments. Other features include online and offline reports for
current and historical data, and daily, weekly, monthly, and annual
reports that are electronically dispatched to all the interested parties,