Power Quality Fundamentals and Monitoring Ross M. Ignall Systems Applications Manager, Dranetz-BMI rignall@dranetz-bmi.com

What We Will Cover… Defining Power Quality and Reliability PQ References & Fundamentals Monitoring, Measuring High Reliability Facilities Case Studies

WPT Power Monitoring Hardware Devices Data Acquisition Devices measure and monitor power Aggregation of Distributed Generation load curtailment of power sales Data Acquisition Devices measures physical processes Software and Consulting Services power quality and distributed generation

Defining Power Quality & Reliability

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.”

It’s dependant on your susceptibility. What Does That Mean? Given the quality of supply do I have to worry about problems with my equipment or systems? It’s dependant on your susceptibility.

What is my susceptibility to power problems? What You Should Be Asking… What is my susceptibility to power problems? What is my economic exposure to such problems? $$$$

Types Of Power Quality Problems

Customer’s Perspective* Who’s Problem Is It? Customer’s Perspective* * Georgia Power Survey

Who’s Problem Is It? Utility Perspective* * Georgia Power Survey

electrical environment, The Big Picture It’s the complete electrical environment, not just the quality of supply

What You Should Be Asking… Does my power system have the capacity for my present needs? How about future growth? Be Proactive!

An Analogy… “Just because I have blank checks doesn’t mean that I have money in the bank to cash them” Ron Rainville, COO, US Data Centers

Some Factoids

Power Quality Factoids $50 billion per year in the USA is lost as a result of power quality breakdown. SOURCE: EPRI, 2000 Half of all computer problems and one-third of all data loss can be traced back to the power line. SOURCE: Contingency Planning Research, LAN Times Sandia National Laboratories estimates power quality and reliability problems cost US businesses approx. $150 billion annually in lost data, materials and productivity—60% are sags In 1999, the amount lost as a result of power quality in the US was five times the amount spent on power quality worldwide

…The data center houses 45,000 square-feet of computer floor space …The data center houses 45,000 square-feet of computer floor space. In one database, the company has consolidated $1.6 trillion of life insurance information. Energy Decisions, June 2001 During power supply shortages, utilities are generally permitted to have line voltage reductions, so-called “brown outs,” to cope with seasonal power demands…But if equipment is already operating on the low end of nominal voltage then the brown-out may cause excessive heat dissipation in motors and electronic equipment. Building Operation and Management, May 2000

Power Density Factoids Traditional data center or large office building – 20-30 W/sq. ft., Internet Data Center, on-line brokers, web hosts – 100-150 W/sq. ft. A web-enabled Palm Pilot requires as much electricity as a refrigerator Mark Mills Transformation: Former 16 story Macy’s building used to consume 10 W/sq. ft. Now a telecommunications hotel that according to the utility could require 50 W/sq. ft. NY Times, July 3, 2000

Costly Downtime! Industry Avg cost of downtime ($/hr) Brokerage $6,450,000 Credit Card $2,600,000 Pay Per View $150,000 Home Shopping $113,000 Catalog Sales $90,000 Airline Reservations $90,000 Tele-Ticket $69,000 Package Shipping $28,000 ATM Fees $14,400 Source: 7x24 Exchange

Introduction to Power Quality

Power Grid Review GENERATOR 13.8kV-24kV L O A D DISTRIBUTION 34.5k-138kV 4k-34.5kV 12,470Y/7200V GENERATOR 13.8kV-24kV CONSUMER 4160Y/2400 480Y/277V 208Y/120V 240/120V TRANSMISSION 115k-765kV

Generation 50/60hz ‘Pure’ Sine Wave Various Voltages Types Chemical Mechanical Nuclear Solar

Transmission Those big towers Voltage High Current Small Efficiency of Transmission Power Delivered to the Load Power Supplied From Generator

Distribution Typically 13kV Commercial/Industrial - Three Phase, 480/277V Residential - Split Phase 480V 13kV 480V 480V

Single Phase Circuit Diagram Is V line L O A D Vn

Can Wiring and Grounding Affect Power Quality? “That’s one of the things about living in an old house that drives me nuts. Never enough outlets!”

ACTUAL SINGLE PHASE CIRCUIT DIAGRAM Is Vpcc Vdp V line L O A D L1 R1 L2 R2 l n2 I n1 Vn L3 R3 L4 R4 Vg L5 R5 L6 R6 I g2 l g1

Sources Of Power Problems Referenced at the utility PCC (point of common coupling) Utility lightning, PF correction caps, faults, switching, other customers Internal to the facility individual load characteristics wiring changing loads

Power Quality References & Terms

IEEE Standards Coordinating Committee SCC-22 Oversees development of all PQ standards in the IEEE Meet at both Summer and Winter Power Engineering Society meetings Coordinate standards activities Progress reports Avoid overlap and conflicts Sponsors task forces to develop standards 1433 Task Force to pull together terms. IEEE & IEC

IEEE Standard 1159-1995 Definition of Terms Monitoring Objectives Instruments Applications Thresholds Interpreting Results

IEEE 1159 1159.x Task Force 1159.3 Task Force Data Acquisition & Recorder Requirements for 1159-1995 Combination of 1159.1 & 1159.2 Coordination with IEC standards (61000-4-30 and revisions) New recommended practice to be developed by July 2001 1159.3 Task Force Power Quality Data Interchange Format (PQDIF) Format for the exchange of PQ and other information between applications Developed by Electrotek Concepts

IEEE 519-1992 Recommended Practice For Harmonics Recommends Limits at the PCC Voltage Harmonics Current Harmonics Ongoing work to modify IEEE 519-1992 Limits for within a facility Frequency dependant

International Electrotechnical Commission (IEC) International standards for all electrical, electronic and related technologies. IEC Study Committee 77A – Electromagnetic Compatibility, presently 5 Working groups SC77A/WG 1: Harmonics and other low-frequency disturbances SC77A/WG 2 : Voltage fluctuations and other low-frequency disturbances SC77A/WG 6 : Low frequency immunity tests SC77A/WG 8: Electromagnetic interference related to the network frequency SC77A/WG 9: Power Quality measurement methods

Types Of Power Quality Disturbances (as per IEEE 1159) Transients RMS Variations Short Duration Variations Long Duration Variations Sustained Waveform Distortion DC Offset Harmonics Interharmonics Notching Voltage Fluctuations Power Frequency Variations

Transient Characteristics High frequency "event" also called Spike, Impulse Rise time (dv/dt) Ring frequency Point-on-wave Relative versus Absolute amplitude Multiple zero crossings

Transients Unipolar Oscillatory Bipolar Notching Positive Negative 200 100 -100 -200 Negative Multiple Zero Crossings

 Transients Possible Effects Possible Causes • Data corruption • Equipment damage • Data transmission errors • Intermittent equipment operation • Reduced equipment life • Irreproducible problems Possible Causes • PF cap energization • Lightning • Loose connection • Load or source switching • RF burst 

Power Factor Correction Capacitor Transient A transient power quality event has occurred on DataNode H09_5530. The event occurred at 10-16-2001 05:03:36 on phase A. Characteristics were Mag = 478.V (1.22pu), Max Deviation (Peak-to-Peak) = 271.V (0.69pu), Dur = 0.006 s (0.35 cyc.), Frequency = 1,568. Hz, Category = 3 Upstream Capacitor Switching

RMS Voltage 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)

RMS Voltage Variations -200 -150 -100 -50 50 100 150 200 Sag Swell Interruption

SAG SOURCE GENERATED DURATION fault clearing schemes may be series of sags (3-4) MAGNITUDE distance from source feeder topology cause LOAD CURRENT usually slightly higher, decrease, or zero

PQ Rule For a source generated Sag, the current usually decreases or goes to zero

PQ Rule For a source generated Sag, the current usually decreases or goes to zero

SAG LOAD GENERATED DURATION type & size of load MAGNITUDE LOAD CURRENT usually single event per device MAGNITUDE wiring & source impedance LOAD CURRENT usually significantly higher

For a load generated Sag, the current usually increases significantly. PQ Rule For a load generated Sag, the current usually increases significantly.

Motor Starting - Another Cause of Sags

Motor Starting – Inrush Current with decay

SWELLS Sudden change in load Line-to-ground fault on another phase Often precede a sag

SWELLS when Load Drops Off

Voltage Variations Sags/Swells  Possible Causes • Sudden change in load current • Fault on feeder • Fault on parallel feeder Possible Effects • Process interruption • Data loss • Data transmission errors • PLC or computer misoperation • Damaged Product

Magnitude & Duration Visualization CBEMA ITIC Equipment Susceptibility 3-D Mag-Dur DISDIP

IEEE 446 - 1995 Limits

Information Technology Industry Council (ITIC) Curve

Another Use of ITIC Curve but vendor had tighter tolerances for outputs

Another Perspective – 3D Mag-Dur Histogram

Frequency Usually not the utility Sources of frequency problems Co-gen UPS Engine generator systems Clocks run fast 1 12 2 3 4 5 6 7 8 9 10 11

Harmonics

What is a harmonic? An integer multiple of the fundamental frequency Fundamental (1st harmonic) = 60hz 2nd = 120hz 3rd = 180hz 4th = 240hz 5th = 300hz …

Linear Voltage / Current No Harmonic Content

Non-Linear Voltage / Current Harmonic Content

NEC 1996: Non - Linear Load "A load where the waveshape of the steady-state current does not follow the waveshape of the applied voltage." voltage current

Harmonics Steady state distortion Periodic or continuous in nature IEEE-519-1992 / US harmonics IEC 61000-3-2&3 European harmonic limits

Harmonic Measurements Total Harmonic Distortion (THD) Ratio, expressed as % of sum of all harmonics to: Fundamental (THD) Total RMS Load Current (I TDD only) Individual Harmonics 2, 3, 4, 5, 6…50+ Fourier Transform, FFT, DFT Interharmonics Content between integer harmonics

Composite Waveform

Harmonic Spectrum

PQ Rule Symmetry Positive & Negative halves the same: Even harmonics usually do not appear in a properly operating power system. Symmetry Positive & Negative halves the same: Only odd harmonics. If they are different: Even & Odd harmonics

Harmonics (sustained) Possible Causes • Rectified inputs of power supplies • Non-symmetrical current • Intermittent electrical noise from loose connections Possible Effects • Overload of neutral conductors • Overload of power sources • Low power factor • Reduced ride-through 

Electronic Loads Cause Excessive Neutral Currents Phase A (50 Amps) Phase B (50 Amps) Phase C (57 Amps) Neutral (82 Amps)

Additive Triplen Harmonics

Equipment Susceptibility Least Susceptible Electrical Heating Oven Furnaces Most Susceptible Communications Data Processing Zero crossing Clock Circuits Transformers, Motors, other inductive loads

IEEE 519 Harmonic Limits Limits depend on ratio of Short Circuit Current (SCC) at PCC to average Load Current of maximum demand over 1 year For example, Isc/IL < 20, odd harm <11 = 4.0% Isc/IL 20<50, odd harm < 11 = 7.0% Isc/IL >1000, odd harm > 35 = 1.4%

IEEE 519 Harmonic Limits Voltage Harmonic Limits depend on Bus V For example, 69Kv and below, ind. harm = 3.0% 69Kv and below, THD= 5.0% 161kv and above, ind.harm = 1.0% 161kv and above, THD = 1.5%

Harmonics Demo Tool

Voltage Unbalance Several ways to calculate Small unbalance can cause motor overheating (3% results in 10% derating) Caused by Unequal loading Unequal source impedance Unequal source voltage Unbalanced fault

Voltage Fluctuation

Voltage Fluctuation Amplitude variation 1-30 Hz Extent of light flicker depends on type of lights amplitude and frequency of variation person's perception Typical causes High current loads, like arc furnaces Windmill-generated power

Voltage Flicker

How Many Can You Find?

Case Study Laser Printer

TIMEPLOT - LINE VOLTAGE vrs NEUTRAL-GND VOLTAGE Vl-n= 120 --> 108 45 seconds Vn-g = 0 --> 6V

SAG when heater turns on V l-n I load V n-g

Overlay Waveforms - Heater turn on

Current Waveform - heater on

HARMONIC DISTORTION - heater on 2.3% Harmonics V l-n 4.4% Harmonics I load Harmonics V n-g

Waveforms when heater turns off V l-n I load V n-g

Harmonic Distortion - Idle 2.3% Harmonics V l-n 94% Harmonics I load Harmonics V n-g

Current With Printer Idle

EQUIVALENT CIRCUIT I Load V Load + - + - 0.6A @ 121V 10.4A @ 117V 0.47 ohms + Source Impedance 0.6A @ 121V 10.4A @ 117V 121 Vac Idle Load 202 ohms Heater Load 11.9 ohms - + V n-g -

OBSERVATIONS and PARAMETERS Nearly Sinusoidal Current Low Harmonic Distortion (4%) Voltage and Current In-phase Power Factor Near One Flat-topping of Voltage when Idle Corresponds with Current Pulse

OBSERVATIONS and PARAMETERS Line Voltage Negative Transient on Turn on Corresponds with Vn-g Positive Transient Nearly Constant Repetition Rate

SIMILAR SITUATIONS Coffee Pot Coke Machine Heat Pump

Monitoring, Measuring & Managing High Reliability Facilities

Why Monitor Your Electrical Supply?

Paradigm Shift? You may no longer be able to rely on the utility to be your primary source of power! Be Prepared

Why Monitor Your Electrical Supply? Quality of supply is of paramount importance Huge investment in protection & mitigation is not a guarantee! You have a high economic exposure Your facility is core to your business or maybe is your business You already monitor other critical items Your electrical environment is just as important You need to balance your needs with available supply Loading, cost allocation, etc

You May Already Monitor Your Facility Traditional Data Center Building Management Systems (BMS), Human Machine Interface Software (HMI) Wonderware, Sitescan, ALC, Datatrax, etc Via Bacnet, Lonworks, Incomm, modbus, etc Internet Data Center Network Operations Center (NOC) HP Open View, etc Via SNMP

What You May Already Monitor Traditional Data Center UPS - On Bypass, other alarms Traditionally do not measure quality Sub Metering HVAC, Fire, Security Internet Data Center Network/System Health Electrical Supply is often overlooked Quality of supply, Energy/cost allocation Power monitoring can interface with existing systems for single point alarming, logging, etc…

Reactive — Forensic, after the fact. Approaches to Power Monitoring Reactive — Forensic, after the fact. Proactive — Anticipate system dynamics Be Proactive!

Reactive Approach Problem Solving, hopefully you’ll find it! Portable instrumentation typically used

Permanently installed monitoring systems Proactive Approach Permanently installed monitoring systems Anticipate the future – on-line when trouble occurs Monitor system dynamics Preventive Maintenance, Trending, identify equipment deterioration Be Proactive!

Use a PQ instrument for PQ monitoring! Power Quality vs. Power Flow Power Quality Monitoring - Quality of Supply Monitor for harmful disturbances, harmonics, etc Microsecond, Sub-Cycle Measurements In close accordance with IEEE 1159 & IEC Power Flow Monitoring - How much, cost, when & where? Energy & Demand, Measured over seconds Be Careful! False sense of security Blind to common PQ problems Use a PQ instrument for PQ monitoring!

Comprehensive Power Monitoring Combined Power Quality and Flow Monitor PQ at critical locations Utility service, UPS, PDU’s, loads Energy provided along with PQ Monitor Energy at less critical locations & individual loads Loading Sub Metering Cost Allocation, etc…

Emerging Technologies Reduced Cost Web monitoring Networked systems Native web access Maximize Assets Sharing of information among systems and groups within the organization Expert Systems Enterprise Systems Pull together various separate systems

Enterprise Systems Traditional Facilities Power monitoring system interfacing with building management, HMI or other systems Notification, metering, trending OPC. Modbus, e-mail Internet Data Center Interface with Network Operations Center (NOC) Simple Network Management Protocol (SNMP)

Expert Systems Reduced budgets means less people! Less expertise Analysis of Data in order to Identify Problems Automatic, no user intervention, results embedded in data Identify certain disturbances and directivity. Upstream or downstream Answers Questions Such As… Was that Sag from the utility or within my facility?

Expert Systems UPS Performance Verification Correlation of Input vs. Output Verify continued performance over time Proactively identify downstream problems Monitor UPS status via analog/contact inputs Remotely access UPS status signals Compare recorded data to UPS status

Expert Systems

Expert Systems Automatically Identifies the Transient as a Capacitor Switching Operation

Where To Monitor? UPS Output Is your UPS working as designed? Utility Service Entrance Evaluate your energy provider Monitor redundant feeds UPS Output Is your UPS working as designed? Evaluates critical bus as problems could be downstream PDU/Distribution Provides the ability to identify the source of a problem. Why did that breaker trip? Loading/Cost allocation Actual loads

Case Study

DHL Airways Call Center Tempe AZ Services DHL customers nationwide Newly Constructed, went online in June 2000 Toshiba 7000 Series UPS Three 300KVA parallel redundant units Facility manager has nationwide responsibilities Current Expansion Plans

DHL Objectives Benchmark performance Ensure future reliability Easily troubleshoot any problems that may occur Automatic notification Remotely monitor over DHL network Since the facility is new and due to its critical nature, monitoring approach was very proactive

DHL Monitoring System Monitoring Points UPS Input (Utility Supply) UPS Output (Critical bus) Connected to DHL Intranet Dial-up modem connection Web browser access from anywhere within DHL Automatic E-mail notification Web browser access from anywhere with a dial-up connection

Known Problems? None! Facility operating as planned No Outages or other major problems identified No UPS Alarms

50+ Disturbances in the first few months Utility Supply 50+ Disturbances in the first few months

UPS Output No disturbances

Utility Monitoring Summary Uncovered problems with the utility supply 50+ disturbances recorded over a 2 month period. Sags, transients, waveshape distortion Results reported to the utility, they did not know Utility investigation Faulty relay caused the majority of the disturbances. Corrected

UPS Output Monitoring Summary No disturbances on the conditioned UPS output Output regulated to within manufacturers specifications UPS mitigated many disturbances on the utility feed Did what they paid for Justified the investment

Conclusion Being proactive uncovered problems with the utility supply that required correction Continuous monitoring proved power conditioning equipment worked as design and to manufacturer’s specifications. Protected loads were unaffected Provided justification to management for power monitoring systems at other key facilities Load profiling helping to determine power requirements of a planned expansion

Case Study

Major Financial Institution New York City Worldwide company with several facilities in NY & NJ 3 UPS Modules 2 static, 1 rotary

Problem Utility Sag Damaged elevator controls No UPS alarms No reported problems with critical systems 02/19/2002 00:29:29.26 PMODULE INPUT Temporary Sag Rms Voltage AB Mag = 366.V (0.76pu), Dur = 3.300 s, Category = 2, Upstream Sag SYSA Input Mag = 353.V (0.73pu), Dur = 3.300 s, Category = 2, Upstream Sag SYSB Input Mag = 372.V (0.78pu), Dur = 3.300 s, Category = 2, Upstream Sag

Utility Sag Utility Supply RMS Trend Utility Supply Waveforms

Corresponding UPS Swell Utility Supply UPS Swell UPS Output

Conclusion Utility sags damaged elevator controls. Corresponding UPS Swell coincident with Utility return to normal. Cause of Swell being investigated… Possible effects of Swells: Damaged power supplies and other devices. Without monitoring would have never seen this. The next time it could be worse.

Case Study

Air Route Traffic Control Center (ARTCC) Monitoring System Federal Aviation Administration Air Route Traffic Control Center (ARTCC) Monitoring System

Simplified Air Traffic Flow ARTCC ARTCC ARTCC TRACON TRACON Tower Tower Your Flight

FAA’s Objectives Monitor critical points throughout each ARTCC Determine present status of each ARTCC Facility Is the electrical supply operating within design parameters? Catch problems before they occur Change approach from Reactive to Proactive Correlate power quality to status indicators, panel meters, transfer switch positions, etc

FAA’s Objectives Benchmark long term performance in order to improve reliability Compare measured parameters to simulations Have web browser access from anywhere within the FAA system Local ARTCC personnel OKC Airway Operational Support (AOS) personnel

Monitoring System Monitor 15 points for quality of supply & energy Utility Service Generators UPS’s Key distribution points Critical Power Centers In parallel monitor other data such as Transfer switch & breaker positions Panel meters Misc indicators Web based access to each site via intranet

Initial Results Key points operating out of design specs Ex: Adjust transformer taps Routine maintenance not always performed as per procedures Wiring inconsistent with drawings

Thank You! Questions? Power Quality Fundamentals and Monitoring Ross M. Ignall Systems Applications Manager, Dranetz-BMI rignall@dranetz-bmi.com