The Role of Distributed Generation in Power Quality and Reliability

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Table A.1 Power Quality Variations 8 Categories Spectral Content Typical Duration Typical Magnitudes 1.0 Transients 1.1 Impulsive 1.1.1 Voltage > 5 kHz 5 kHz 2 min. 3.2 Under-voltages > 2 min. 4.0 Interruptions 4.1 Momentary < 2 sec. 0 4.2 Temporary 2 sec. – 2 min. 0 4.3 Long-term > 2 min. 0 5.0 Waveform Distortion 5.1 Voltage 0-100 th harmonic steady-state 0-20% 5.2 Current 0-100 th harmonic steady-state 0-100% 6.0 Waveform Notching 0-200 kHz steady-state 7.0 Flicker
Transients are also called spikes, impulses, and surges. The disturbance may be either impulsive(a step change) or oscillatory (swing from high to low with or without damping). Lightning, electrostatic discharge, load switching, or capacitor switching may cause an impulsive transient. Oscillatory transients are characterized by frequency content and may be caused by switching operations such as energizing a capacitor bank, distribution line or cable, or interruption of current to an inductive load. The most destructive cause of transients is lightning. Transients generated from direct strikes have the greatest potential for damaging equipment—both for the utility and the customer. However, even a strike in the vicinity of the lines can induce enough energy in them to cause a significant transient. Other transient sources include large reactive loads such as power factor correction capacitors. This transient, although less powerful than a lightning strike, still transmits enough energy to cause problems. The same is true when load transfer switching is done whether by the utility or by the customer. Adding or removing a large bulk of the load will often create significant transients. Capacitor banks also can create resonant circuits which cause magnify voltages due to harmonic sources. Basically capacitor in combination with line and load inductance can create a tuned circuit for harmonic (multiples of 60Hz) circuits and thus magnify the voltage. Solutions to equipment upsets caused by transients include the following: A properly installed lightning arrestor system with a separate ground; Transient voltage surge suppressors (TVSS) should be installed at the service entrance or smaller systems protecting individual equipment may be more cost effective; and For the most sensitive equipment additional protection equipment is used such as computer grade power conditioners and ferro-resonant line conditioners. Voltage Sags and Swells Voltage sags and swells are variations in the RMS (root mean squared) voltage from about one half cycle to several seconds. RMS rather than peak-to-peak is how the voltage is measured on an AC system. Sags and swells are characterized by decreased/increased changes in the RMS voltage value, respectively. Sags refer to a reduction in the voltage, while swells deal with a voltage increase. A voltage swell occurs when a single line-to-ground fault on the system results in a temporary voltage rise on the unfaulted phases. Removing a large load or adding a large capacitor bank can also cause voltage swells, though typically of longer duration. Equipment used in modern industrial plants, such as process controllers, PLCs, adjustable speed drives, and robots are affected by sags and swells. When a sag occurs, the power supply inside electronic devices uses some of its stored energy to compensate for the loss of input voltage. If enough energy is lost due to the sag, then the power supply may lose its ability to maintain an exact DC voltage to all the active components, such as integrated circuits, inside the device — even for a few milliseconds. This is long enough to corrupt data in microprocessor-based Appendix A A5 The Role of DG in Power Reliability
Page 1 and 2: The Role of Distributed Generation
Page 3 and 4: Table of Contents EXECUTIVE SUMMARY
Page 5 and 6: EXECUTIVE SUMMARY The nature of bus
Page 7 and 8: Power Quality Costs Industries and
Page 9 and 10: Approximately 90% of the PQ equipme
Page 11 and 12: Table ES2 Mitigation Effectiveness,
Page 13 and 14: New York City, uses its standby die
Page 15 and 16: The Role of Distributed Generation
Page 17 and 18: 2. INTEGRATON OF DISTRIBUTED GENERA
Page 19 and 20: dispatching system as part of the c
Page 21 and 22: Figure 2.7 shows an ultra-high reli
Page 23 and 24: There are no reverse power or direc
Page 25 and 26: 3. CUSTOMER PERSPECTIVE ON POWER QU
Page 27 and 28: egrounding in the machine shop. It
Page 29 and 30: plant specializing in superalloys f
Page 31 and 32: 4. ECONOMIC ANALYSIS OF INTEGRATED
Page 33 and 34: The estimated costs of a hypothetic
Page 35 and 36: 4.3 Distributed Generation Economic
Page 37 and 38: The results show a significant incr
Page 39 and 40: The system has a 90% load factor (w
Page 41 and 42: 5. CONCLUSIONS The project team spo
Page 43 and 44: that can integrate the power electr
Page 45 and 46: APPENDIX A SUMMARY OF POWER QUALITY
Page 47: Figure A.2 Normal Operating Region
Page 51 and 52: Voltage Interruptions Voltage inter
Page 53 and 54: Flicker Flicker is a modulation of
Page 55 and 56: While the typical voltage sag or in
Page 57 and 58: companies, airline reservation syst
Page 59 and 60: Table A.4 Estimated Total Cost of P
Page 61 and 62: $900 million per year market in the
Page 63 and 64: from long-term outages only as it t
Page 65 and 66: Figure A.9 Dynamic Voltage Restorer
Page 67 and 68: Rectifier/Charger: The rectifier/ch
Page 69 and 70: APPENDIX B: REVIEW OF NEW YORK POWE
Page 71 and 72: effective, power quality disturbanc
Page 73 and 74: The Project team reviewed the 2002
Page 75 and 76: NYSEG CAIDI MEASURES 1999 - 2002 WI
Page 77 and 78: Power Quality A section of the 2002
Page 79 and 80: system were the fourth most frequen
Page 81 and 82: The SAIDI (with storm) index showed
Page 83 and 84: B.3 Niagara Mohawk Power Quality 20
Page 85 and 86: Power Quality Investigation Managem
Page 87 and 88: APPENDIX C CASE INFORMATION BASED O
Page 89 and 90: Considered Distributed Generation?
Page 91 and 92: Measures to Increase Reliability Th
Page 93 and 94: Harbec was interested in a renewabl
Page 95 and 96: With the old Unifins, when they wer
Page 97 and 98: Since the blackout, JHMC has not ye
Page 99 and 100:
factor quality correction and/or ad
Page 101 and 102:
generator and 2 -2MW backup generat
Page 103 and 104:
PQ Related Costs Voltage/current sa
Page 105 and 106:
e started and stopped causing curre
Page 107 and 108:
Case Study - Major Network Televisi
Page 109 and 110:
space constraints, and fuel cost un
Page 111 and 112:
APPENDIX D POWER QUALITY GLOSSARY 4
Page 113 and 114:
Forward Transfer Impedance - The am
Page 115 and 116:
Nominal Voltage - The normal or des
Page 117 and 118:
Semiconductor - An electronic condu
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