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Power Quality Electrical Engineering
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PowerQuality Alejandro Roncancio Ing. Eléctrica
Agenda • What is Power Quality? • What is a Power Quality problem? • Power quality Effects • Normativity • Conclusions
What is Power Quality? • Power Quality is a set of metrics used to benchmark the quality of the electric service provided to customers. Taken from: http://www.heco.com/portal/site/heco/menuitem.508576f78baa14340b4c0610c510b1ca/=article
What is a Power Quality Problem? • “Any occurrence manifested in voltage, current, or frequency deviations that results in failure or mis-operation of end-use equipment.” Source: http://engineering.electrical-equipment.org/tag/power-quality
Sources Of Power Problems Utility • Lightning, PF correction caps, faults, switching • Impact from other customers Internal to the facility • Individual load characteristics, motors, ASDs • Computers, microprocessors • Wiring • Changing loads Typically, 70% of all PQ events are generated within the facility
Types Of Power Quality Disturbances Transients: Momentary (& undesirable) high frequency sub-cycle “event”. May also be called a Spike, Surge or Impulse • Characteristics of a Transient: • Rise time (dv/dt) • Ring frequency • Point-on-wave • Multiple zero crossings • Magnitude Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances Transients: Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances RMS Variation A change in the RMS voltage. Typically 16 ms (1 cycle) or longer • Reduction in voltage: Sag • Increase in voltage: Swell • Total interruption of electrical supply for duration from few milliseconds to one or two seconds: Interruption Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances RMS Variation Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
IEEE 1159 Characterizations(RMS Variations) • Instantaneous (0.5 - 30 cycles) • Sag (0.1 - 0.9 pu) • Swell (1.1 - 1.8 pu) • Momentary (30 cycles - 3 sec) • Interruption (< 0.1 pu, 0.5 cycles - 3s) • Sag • Swell • Temporary (3 sec - 1 minute) • Long Duration (beyond 1 minute)
Types Of Power Quality Disturbances Voltage fluctuation: (Flicker) Oscillation of voltage value. Humans can be sensitive to light flicker caused by voltage fluctuations. Generally speaking, flicker can significantly impair our vision and cause general discomfort and fatigue. Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances Voltage fluctuation: (Flicker) Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
Types Of Power Quality Disturbances Harmonic Distortion Voltage or current waveforms assume non-sinusoidal shape. The waveform corresponds to the sum of different sine-waves with different magnitude and phase, having frequencies that are multiples of power-system frequency Source: Power Quality , Reliability and Management, Dranetz Company, May 2012
POWER QUALITY EFFECTS • Energy losses increase • Negative effects on industrial production and Economy • Costs increase • Reliability decrease
Effects Of Power Quality Disturbances Source: The Cost of Power Quality, Copper Development Association, March, 2001
Normativity • Europe: EN50160
Normativity • USA:
Normativity • Colombia: • “ComiteCalidad de Potencia”
Conclusions • The availability of electric power with high quality is crucial for the running of the modern society. • Voltage sags are considered the most common Power Quality problem, When sourced from the utility, they are most commonly caused by faults on the distribution system
Conclusions • The costumers need to use devices less sensitive since the 70% of PQ problems are into the Facility. • The Financial sector is the most affected by the problems with Power Quality. It needs electrical energy with high percentage of availability to function properly.