Power Quality Basics_Complex Compatibility_Aclara
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The document discusses power quality, outlining its significance for both utility customers and energy providers, highlighting economic impacts like equipment damage and production losses. It introduces key concepts and standards related to power quality, including the IEEE standards and the ITI curve, which define acceptable voltage ranges and compatibility for sensitive equipment. Additionally, it details various power quality events, their causes, and effects on electrical systems.
Power Quality Basics_Complex Compatibility_Aclara
- 1. Power Quality Basics Complex Compatibility Chris Prince – Sr. Application Engineer
- 2. Power Quality is a major concern to utility customers and the utility. For the energy consumer, the economic impact of power disturbances can range from hundreds of dollars in equipment repair to millions of dollars in production losses and downtime. For utilities, disturbances lead to customer dissatisfaction and losses in load and revenue. This presentation clarifies the unique electrical relationship between utility and customers relative to Power Quality. Introducing Power Quality terminology, tools to determine compatibility, and data that is available for analysis. overview page 02
- 3. challenge. power delivered outside voltage limits damages customer equipment and results in annual grid losses of 1.5 Billion MWh
- 4. define power quality page 04 IEEE 1159 The concept of powering and grounding sensitive equipment in a manner that is suitable for the operation of that equipment. IEEE Standard 1159-1995 Handbook of EE Good power quality, however, is not easy to define because what is good power quality to a refrigerator motor may not be good enough for today’s personal computers and other sensitive loads. For example, a short (momentary) outage would not noticeably affect motors, lights, etc. but could cause a major nuisance to digital clocks, videocassette recorders (VCRs) etc. Standard Handbook of Electrical Engineers, 14th Edition (2000) IEEE 100 The concept of powering and grounding sensitive equipment in a manner that is suitable for the operation of that equipment and compatible with the premise wiring system and other connected equipment. IEEE 100 Authoritative Dictionary of IEEE Standard Terms
- 5. power grid system of systems PATH FLOW Note: R (resistance) is commonly used to define Ohm’s Law. Z (impedance) is more accurate and includes resistance, capacitance, and inductance. Every Cable or Wire has resistance, inductance and a capacitance to ground, earth and other conductors. page 05
- 6. optimal source voltage page 06 V Peak = +170 V V RMS = 120 V Frequency = 60 Hertz = 1 cycle every 0.0167 secs Single Phase Voltage V Line-Line = 480 V V Line-Neu = 277 V (shown) V L-N Peak = +391 V Frequency = 60 Hertz = 1 cycle every 0.0167 secs Shift in Phase = 1/3 cycle = 0.006 sec Polyphase Voltage
- 7. utility & customer relationship page 07 Voltage is created at the terminals of the UTILITY generator. V voltage CUSTOMER Load dictates the flow of current and characteristics of the current. I current UTILITY & CUSTOMER have no control of the time of occurrence or duration of events. t time Frequency is created at the UTILITY generator, but highly influenced by the CUSTOMER Load. f frequency POWER QUALITY is a compatibility between the UTILITY & CUSTOMER with shared responsibility & influence.
- 8. Range Above Below 2 cycles to 30 cycles 0.03 sec to 0.5 sec 120% of Nominal 70% of Nominal 30 cycles to 600 cycles 0.5 sec to 10 sec 110% of Nominal 80% of Nominal 600 cycles and longer… 10 secs and longer… 110% of Nominal 90% of Nominal compatibility defined Range Above 0.1 msec 500% of Nominal 1 msec 200% of Nominal 3 msec 140% of Nominal after 3 msec 120% of Nominal SUB-CYCLEFULLCYCLE The ITI (CBEMA) Curve is published by Technical Committee 3 (TC3) of the Information Technology Industry Council (formerly known as the Computer & Business Equipment Manufacturers Association). The ITI Curve describes an AC input voltage envelope which typically can be tolerated (no interruption in function) by most Information Technology Equipment. http://.www.itic.org/technical/iticurv.pdf page 08
- 9. 0 50 100 150 200 250 300 350 400 450 500 0.0001 0.001 0.01 0.1 1 10 100 70% 20ms 0.5s3ms ITI curve Information Technology Industry Council Duration (seconds) Voltage%Nominal Acceptable Range No Damage or Disruption should occur. Damage Range Damage likely to occur. Disruption probable. Misoperation Range Disruption likely to occur. Damage may occur. 1Cycle 3Cycles 6Cycles 60Cycles Typical Breaker Operation500%, 0.01c 200%, 1ms 140%, 3ms 120% 110% 90% 80% page 09
- 10. power quality events Transients Impulsive Nanosecond Microsecond Millisecond Oscillatory Low Frequency Medium Frequency High Frequency TYPICAL CAUSES Lightning Switch Operation Capacitor Energizing Short-Duration Variations Instantaneous Momentary Temporary Interruption Sag (Dip) Swell TYPICAL CAUSES Transmission Fault Clearing Distribution Fault Clearing Regulator Mis-Operation Long-Duration Variations Interruption, Sustained Undervoltages Overvoltages TYPICAL CAUSES Circuit Outage Tap Changer Failure Line Capacitor Control Failure (Unbalance) page 010
- 11. power quality events Voltage Unbalance Creates inefficient operation of Motors. Leads to shortened Motor Life. Typical 0.5% - 2% TYPICAL CAUSES Single Phase Loads Unbalanced Circuit Loading Regulator/Line Capacitor Failure Waveform Distortion Harmonics Notching Noise TYPICAL CAUSES Electronic Loading Harmonic Resonance SCR Load (Silicon Controlled Rectifier) Power Frequency Variation De-stabilization of Load to Generation Balance TYPICAL CAUSES Sudden Load Change Weak System Supply page 011
- 12. harmonics page 012 Equipment Effect Capacitor Banks Overheating Insulation Breakdown Failure of Internal Fuses Protection Equipment False/No Tripping Meters Inaccurate measurement Transformers Overheating Motors Increased Noise Level Overheating Additional Vibrations Harmonics are currents and resulting voltage drops that are frequencies based upon the Fundamental 60Hz waveform, but at higher multiples. 1st Harmonic (Fundamental) 3rd Harmonic 5th Harmonic Resulting Current Any periodic waveform can be broken into a series of sine waves with amplitudes and phase relationships. This is known as a Fourier analysis. Below is an example of 3 waveforms added to form a resultant that is approaching a square waveform.
- 13. service voltage page 013 Service Voltage Utilization Voltage Service Voltage Utilization Voltage Range A is the OPTIMAL operating range. Range B is ACCEPTABLE, but should be used INFREQUENTLY. ANSI C84.1 provides a standard for the Utility Service voltage and the Utilization Voltage (allowing for service wire voltage drop). It stipulates a NORMAL range, and an ACCEPTABLE range that can be used in cases of system damage.
- 14. flicker in the eye of the beholder… page 014 Flicker is challenging because a technical system response and physiological perception must both be managed in the solution. The chart is the result of several research studies, and is the basis of an industry reference standard for mitigating flicker cases.