Title :
Large adjustable speed and soft-started drives with long cable lengths
Author :
Endrejat, Frieder ; Burmeister, Peter ; Pillay, Pragasen
Author_Institution :
Sasol Technol., Secunda, South Africa
Abstract :
The popularity of large voltage source inverters (VSIs) has increased for a wide range of applications. An overview is given on how cable length challenges associated with VSIs can be overcome. Load commutated inverters (LCIs) are however in many cases still more suitable for pure soft-start applications and for very large drives. Very limited literature does however exist describing how to overcome long cable-length problems in LCI applications. The associated overvoltage phenomenon due to resonance and voltage distortion is explained. Case studies and simulation results are presented based on actual configurations in large petrochemical plants with motor ratings ranging from 17 MW to 55 MW with cable distances up to 3 km. An evaluation is performed to determine when additional electrical filter and rotor position detection equipment are required. It is shown that with correctly designed systems the applicable motors can be started without the presence of unacceptable overvoltages, pulsating air-gap torques or shaft resonances. A general design approach is described to determine the requirements for VSIs and LCIs. Ultimately it is shown that effective, safe, reliable and low cost solutions exist to extend the capabilities and application of VSI and LCI systems.
Keywords :
electric drives; invertors; power cables; synchronous motors; adjustable speed drive; air-gap torques; electrical filter; load commutated inverter; long cable length; power 17 MW to 55 MW; resonance distortion; rotor position detection equipment; soft-started drives; synchronous motors; voltage distortion; voltage source inverter; Air gaps; Commutation; Filters; Inverters; Performance evaluation; Petrochemicals; Resonance; Rotors; Shafts; Voltage control; adjustable speed drive; load commutated inverter; medium voltage; synchronous motors; voltage source inverter;
Conference_Titel :
PCIC Europe, 2009. PCIC EUROPE '09. Conference Record
Conference_Location :
Barcelona
Print_ISBN :
978-1-4244-3975-1
Electronic_ISBN :
978-3-9523-3334-1