ECET Modern Power

Transcription

1 ECET Modern Power

2 Course Instructors

3 Course Philosophy This course is an introduction to a wide range of electrical energy systems technologies. Topics include fundamentals of energy conversion, which includes large- and small-scale generation, energy storage, and end-use. Processes include coal, nuclear, solar, wind, hydro, and biomass and their application in central and distributed power systems. The power grid, microgrids, and smart grid technologies are also explored. The goal is to introduce students to the breadth of technology in the rapidly growing and changing field of energy systems.

4 Learning Objectives and Outcomes Demonstrate the process cycles, theory of operation, and roles of significant equipment for various energy conversion, energy storage, and power distribution technologies Characterize and calculate power, efficiency, environmental, and economic quantities related to various energy conversion, energy storage, and power distribution technologies Discuss some of the problems and trending solutions related to power and energy systems such as technological limitations, environmental impacts, and economic limitations both locally and worldwide

5 Required Material I will provide hand outs periodically. They will be part of the reading. Do not ignore. Youtube Chanel is helpful: Jpiller Boardshorts, ECET 243 Playlist Us

6 Grading Exams/Homework/Projects 40% Laboratory Work 40% Course Performance 20% A 90%-100% B 80%-89% C 70%-79% D 60%-69% F 59% and below

7 Office Hours and Course Communications This document contains the contact information for the course instructor. Please feel free to call, , or text using any of the formats listed. See the following link, as a proper way to contact the instructor. Please extrapolate from this document the proper way to call and text message. I am generally at PUSB during standard hours and weekdays, either in the office (TB 204) or one of the labs. If you need something specific please make an appointment. Please be courteous if you are in need of consultation. If I am in the office and the door is open stop and knock and you will be acknowledged when it is appropriate to enter. If the door is closed please DO NOT KNOCK. That is a sign that consultation is not currently possible and you will need to try one of the other forms of communication to ask for an appointment.

8 And now the Official Syllabus

9 Topic 1 FUNDAMENTALS OF AC POWER

10 Power Review DC Circuits Inductors Resistance = = 2 Capacitor Resistance = =

11 AC Single Phase Power Inductors and Capacitors store energy DC steady state this is a constant voltage flow thus energy stored is constant AC has a sinusoidal wave, thus stead state conditions mean the energy stored varies with time

12 AC Single Phase Power AC power across the Resistor is consumed. What does it turn into? This is Real power it does actual work What is the unit of measure we use to express this?

13 AC Single Phase Power Imagine the flow of AC power into an Inductor Voltage increases over time What does the current do? So the Inductor stores energy, what happens when we hit Vpeak?

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15 AC Single Phase Power So as we hit Vpeak the voltage decreases, thus the power decreases. The stored energy returns to the source This is Reactive Power It does no useful work Capacitors follow the same principal

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18 AC Single Phase Power Reactive Power is measured in VAR, designated with a Q. The phasor sum of Real and Reactive Power is called Apparent Power Apparent Power is measured in VA, designated with a S

19 Real, Reactive, and Apparent Power = 2 (90 Direction) = (-90 direction) X L and X C unit is Ohms (Ω)

20 Real, Reactive, and Apparent Power DC Power P = IV = I 2 R =V 2 /R Apparent power Inductive Loads, Current Lags Capacitive Loads, Current Leads Cannot just multiply the magnitudes, must take angle into consideration.

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23 Real, Reactive, and Apparent Power The Math Polar: S = ( V 0 )( I +q) = ( V I ) +q Rectangular: S = S cosq +j S sinq = P + jq SOH CAH TOA P = S cosq Q = S sinq

24 Real, Reactive, and Apparent Power

25 Topic 2 POWER FACTORS, POWER QUALITY, AND CORRECTIONS

26 Power Factor Power Factor is the ratio of Real power to Apparent Power Expressed in Decimal or Percentage Capacitive loads have a Leading Fp Inductive loads have Lagging Fp Unity Power Factor is Perfect, totally Resistive

27 Power Factor Unity, F P = 1.0 Ideal, 0.9 to 1.0 Optimized for cost, Reactive power does no work but adds to the load Excessive Reactive loads mean increased size of wire, transformers, etc. = Excessive Cost with No Return

28 Demand is measured in kilowatts, kw 100 Watt Bulb Consumption is measured in kilowatt-hours, kwh 1000 Watts or 1 kilowatt

29 Electricity use overtime, kwh Consumption charges are billed in kwh used per billing period. The period is usually one month. How does this relate to Demand?

30 Read an Industrial Electricity Bill Bill To: Rite Stuff Paper Co, Inc. Date 09/24/ Backwater Road Acct#: Happy Hollow, GO Site: 100 Backwater Rd Electric Service Rendered from 08/20/07 to 09/26/07 Schedule LP Meter Number: Demand (KVA) Pres Reading: Demand Reading 5704 Prev Reading: / Power Factor Consumption: = Act-Demand 6791 Calculation of Bill Facility Charge: Demand Charge: Rate LP Regular 6791 kva x $ , Energy Charge 0 to 1,000,000 kwh X ,000,000 to 10,000,000 kwh x Total Fuel Cost Adjustment x0.004 x Total Billing for Electric Service >>>>>

31 Power Factor Most Loads in Industry are R-L How do we correct an excessively Inductive Load? Capacitors Inductors and Capacitors cancel each other

32 Power Factor Pole Mounted Capacitor Bank Expressed in kvar, not farad

33 Power Factor Real & Reactive Power vs F P Real Load Remain 1W

34 Power Factor Utility Company has Penalties on Customer for low FP Customer generally checks Cost of Correction Devices against Penalties

35 Power Factor If F P is corrected, smaller components or more capacity

36 Using The Previous Example Bill, how do we correct the Power Factor? Bill To: Rite Stuff Paper Co, Inc. Date 09/24/ Backwater Road Acct#: Happy Hollow, GO Site: 100 Backwater Rd Electric Service Rendered from 08/20/07 to 09/26/07 Schedule LP Meter Number: Demand (KVA) Pres Reading: Demand Reading 5704 Prev Reading: / Power Factor Consumption: = Act-Demand 6791 Calculation of Bill Facility Charge: Demand Charge: Rate LP Regular 6791 kva x $ , Energy Charge 0 to 1,000,000 kwh X ,000,000 to 10,000,000 kwh x Total Fuel Cost Adjustment x0.004 x Total Billing for Electric Service >>>>>

37 Current Corrected Demand Reading (kw) Power Factor Act-Demand (kva) Demand Rate Demand Charge Annual Cost A = 1 2 B C = A X B C X $9.00/kVA $61,119 $54,053 $733,428 $648,432 Monthly Savings = $7,083 Annual Savings = $84,996

38 Is it worth it? Depends on the Capacitor that is required to do this.

39 1.875k 3.685k 1.81k

40 A 2kVAR Capacitor can be purchased for $ Excluding labor, with a monthly savings of $7,083 the payback is obvious in this example.

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42 Summary Resistors, Unity Power Factor Inductors, Lagging Power Factor Capacitors, Leading Power Factor Inductors and Capacitors cancel each other Most Loads in Industry are Inductive

43 Topic 2.5 POWER QUALITY AND CORRECTIONS

44 Power Quality What do we mean when we say Power Quality? How often do we loose power Stability of the frequency Presence of Harmonics

45 Power Quality Terms to be avoided Blackout Brownout Dirty/Clean power or ground Power surge Dedicated ground Spike

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47 Power Quality Line Voltage Swells

48 Power Quality Voltage Sag

49 Power Quality Voltage Interruption

50 Power Quality Low Frequency Ring Waves (Transients) High Frequency Ring Waves (Transients)

51 A. B. A. Prohibited Region B. No Damage Region This figure shows the allowable % of Voltage on the Power System: 1. Steady State Tolerances 2. Line Voltage Swells 3. Low Freq. Wave 4. High Freq. Wave 5. Voltage Sags 6. Voltage Interruption

52 Harmonics Voltage or Current Ideally we would have single frequency sinusoids Harmonics are signals that are present whose frequency is an integral multiple of the fundamental frequency

53 Harmonics Fundamental, third, and fifth

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56 Harmonics How do we identify the size of the harmonic content in a waveform? Total Harmonic Distortion (THD)

57 Harmonics What causes harmonics? Non Linear Loads Use to be an issue only the power company and a few industrial users worried about Negative Effects of Harmonics Sensitive equipment to trip off Over-current and overheating in capacitors Overheating and reduction of efficiency in motors Overheating and power loss in transformers Overheating and power loss in all conductors.

58 Harmonics DC Power supplies are a large issue on the network now. They are used in: VFD Electronic Lighting Ballasts Computers All Electronic Device

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60 Harmonics Waveform of Input of a VFD I peak = 425A, I rms =103A

61 Harmonics Single Phase Bridge Rectifier has High 3 rd harmonic content This particular Wave has a Ipeak =425 A and IRMS = 103 A Crest Factor = 425/103 = 4.12% High Harmonic Content

62 Harmonics We can eliminate triplen harmonics with a three phase bridge rectifier

63 Harmonics

64 Effects on System So, what? What problems do harmonics cause? Voltage Distortion, all loads are parallel

65 Effects on System Effects on Meters Average Responding Peak Responding True RMS Meters

66 Effects on System Average Responding, Assume 1V peak-peak Block DC, Rectify, find V DC, multiply by fudge factor 1.111

67 Effects on System If harmonics are present, CF will not be 2 and the ratio of will not be true. The Average Responding Meter will only give a correct RMS reading for a single frequency sine wave

68 Effects on System

69 Effects on System True RMS Meter Samples points, squares, integrates, and takes square root it does the math Will work on multi-frequency sine wave

70 Effects on System Conductors I 2 R heating issues Shared Neutral, 4 wire system, common to de-rate the size of the neutral

71 Effects on System Triplen Currents add on the Neutral Neutral is not protected by a circuit breaker High Neutral currents can cause voltage drops, may require separate Neutral conductors extra $$$

72 Effects of system Excessive heating of Transformers, K rating extra $$$ K1, 60 hz only K4, 9 or 13 increases the size of the conductors by this factor

73 Effects on System Circuit Breakers, use thermal sensors, excessive heat causes early trip Use same technology as an Average or Peak responding meter same problems Can get with True RMS technology extra $$$

74 Effects on the system Also effects Power Factor Telecom Systems Sensor Networks Security Systems

75 Summary Harmonics, extra frequencies in the fundamental waveform Triplen currents, negative effect on the power system