Fault ride through compensation for grid voltage drop events
Asynchronous generators, including doubly-fed rotors, are widely used in the growing number of renewables wind farms. During voltage drops, any slight speed deviation of these rotors will consume large amounts of reactive energy. Due to the large demand for reactive power during significant voltage drops, FRT (Fault Ride Through) regulations have been implemented in many modern grid codes such as the Spanish grid code PO12.3.
A typical voltage drop event is the result of a short circuit on one of the electrical network branches. It can take at least 100-200 ms to isolate the faulty substation, potentially collapsing the voltage stability. Because of this, the majority of modern grid standards are now requiring provision for reactive energy to be generated by local networks during such a fault event.
Reliable reactive energy to support voltage ride through
The most reliable reactive energy solutions are based on capacitor banks in a Static VAR Compensation (SVC) system. However, utilising a SVC as a ride-through solution can have its disadvantages. The provided reactive current is proportional to the voltage, while the reactive power is proportional to the second power of the voltage (V²).
A fault ride through solution
The Equalizer RT system is the Elspec ride through solution for use with asynchronous turbines and is based on the existing and proven technology used in Elspec Real Time Static VAR Compensation systems already is use around the world.
The Equalizer is a transient free static compensation system which has been modified in order to boost the supplied kVAr capacity for short time voltage dips events and is based on the following features:
- Transient-free connection of capacitors
- Voltage Control operation mode – (Already optimised to fulfil grid code requirements such as the Spanish PO12.3 Grid Code)
- Ultra fast acquisition time – full compensation within less than 10mSec
