Power Quality Aspects of Electric Traction Sh. R.N Lal Sr. Executive Director/TI & Sh. S. Bhatnagar Jt. Director/ TI RDSO/Luckow. Out Line of the presentation.
power quality system.
The term power quality is used to describe the extent of variation of the voltage, current and frequency on the power system. The variation of voltage and current can either be in terms of magnitude or waveform shape/distortion.
1. Compensation of reactive power to improve power factor.
2. Compensation or elimination of harmonics in the system, for improvement in voltage form factor and reduction of line losses.
3. Correction of voltage imbalance in 3 phase supply system.
4. Correction of short duration voltage disturbances i.e. sag , swell and flickers.
Reactive power compensation Methods to improve PF
Self commutated VAR generators: The fast switching power electronic devices are used to act either as voltage or current fed inverter to inject required amount of leading/lagging reactive KVAR into the system.
--Limit the harmonic current injection from individual consumers so that to prevent unacceptable voltage distortion levels.
--Limit the overall harmonic distortion of the system voltage supplied by the utility.
As reported by CR Average power factor has improved from 0.79 to 0.93 for Lasalgaon ,0.76 to 0.89 for Bhadli, 0.78 to 0.92 for Pimperkhed TSS
(Expected power factor is near Unity, Deciding correct ratings of fixed and variable compensation is very important )
Reduction in THD Voltage Harmonics at Lasalgaon TSS reported from 12.36% to 7.86% at max load.
(Harmonic Filtering is done by Fixed capacitor bank branch of STATCON, Present design in use does not have harmonic cancellation feature )
Selection of DRPC system should be based on applicable tariff conditions to the Railways e.g.