Wind Farm (IG)

A wind farm consisting of six 1.5-MW wind turbines is connected to a 25-kV distribution system exports power to a 120-kV grid through a 25-k

Turbine response to a change in wind speed

Start simulation and observe the signals on the "Wind Turbines" scope monitoring active and reactive power, generator speed, wind speed and pitch angle for each turbine. For each pair of turbine the generated active power starts increasing smoothly (together with the wind speed) to reach its rated value of 3 MW in approximately 8s. Over that time frame the turbine speed will have increased from 1.0028 pu to 1.0047 pu. Initially, the pitch angle of the turbine blades is zero degree. When the output power exceed 3 MW, the pitch angle is increased from 0 deg to 8 deg in order to bring output power back to its nominal value. Observe that the absorbed reactive power increases as the generated active power increases. At nominal power, each pair of wind turbine absorbs 1.47 Mvar. For a 11m/s wind speed, the total exported power measured at the B25 bus is 9 MW and the statcom maintains voltage at 0.984 pu by generating 1.62 Mvar (see "B25 Bus" and "Statcom" scopes).

Operation of protection system

At t=15 s, a phase to phase fault is applied at wind turbine 2 terminals, causing the turbine to trip at t=15.11 s. If you look inside the "Wind Turbine Protections" block you will see that the trip has been initiated by the AC Undervoltage protection. After turbine 2 has tripped, turbines 1 and 3 continue to generate 3 MW each.

Impact of STATCOM

You will now observe the impact of the "STATCOM". First, open the "Three-Phase Fault" block menu and disable the phase to phase fault. Then put the "STATCOM" out of service by double clicking the "Manual Switch" block connected to the "Trip" input of the "STATCOM". Restart simulation. Observe on " B25 Bus" scope that because of the lack of reactive power support, the voltage at bus "B25" now drops to 0.91pu. This low voltage condition results in an overload of the IG of "Wind Turbine 1". "Wind Turbine 1" is tripped at t=13.43 s. If you look inside the "Wind Turbine Protections" block you will see that the trip has been initiated by the AC Overcurrent protection.