t68_protect-equipment-power-quality-solutions.pdf

Copyright 2012 Rockwell Automation, Inc. All rights reserved.

T-68 Protecting Your Equipment through Power Quality Solutions

Dr. Bill Brumsickle Vice President, Engineering Nov. 7-8, 2012

Copyright 2012 Rockwell Automation, Inc. All rights reserved. 2

Agenda

Voltage Sag Protection

Power Quality Events & Voltage Sags

Importance of Power Quality to Industrial Users

What is Power Quality?


Power Quality vs. Power Reliability Power Reliability: Continuity of electric power delivery measured by the number and

duration of power outages (Zero voltage) Outages are tracked by Utilities Power Reliability can be as high as 99.999% availability

Power Quality: Related to fluctuations in electricity, such as momentary interruptions, voltage sags or swells, flickering lights, transients, harmonic distortion and electrical noise Fewer such incidents indicate greater power quality Events go mostly untracked by Utilities Sag & Momentary events can take out a process as many as 20-30 times per year

3

The Grid is designed for Reliability, not Quality


Power Quality

Frequency is regional Determined by HV & EHV network generators Problems are rare

Voltage is area-wide Determined by MV distribution network Problems occur randomly, but with regularity

Current is local Determined by facility loads Problem loads can be identified and resolved Source: DTE Energy website

4


Utility Power Properties of AC Grid

Not always ideal sinusoidal voltages!

Highly interconnected

Transformer and line impedances between generators and loads

Terminal voltage drops with load current

System faults cause significant voltage sags (dips)

Most wiring is overhead Susceptible to lightning, animals, wind-blown

tree branches, etc.

Insulation fails, equipment fails

5

Source: NPR: Power Hungry: Reinventing The U.S. Electric Grid May 1, 2009


Power Quality Problems

All have physical causes

6


Agenda






Electrical Equipment Designed Assuming Power Quality

Operate with input ac voltage variation of 10% Possible new requirements:

Operate through some voltage sags SEMI F47 IEC

Present a unity Power Factor: Current phase angle near zero Current harmonic distortion low

8


Impact of Power Quality Events

Possible Agency, Utility, or Facility Requirements Power Factor correction (current phase angle) Harmonic current limits

Load equipment mis-operation Voltage sags and momentary interruptions Voltage distortion (harmonics, notching) Voltage imbalance or single-phasing High-frequency voltage transients

Load equipment damage High-voltage transients Current inrush following voltage sag

Facility infrastructure damage High-voltage transients Current inrush following voltage sag Overheating due to current harmonics

9


Consumer is Responsible for Power Quality

Utility cannot provide perfect power quality and are not required to. (e.g., Wisconsin PSC 113.0703)

Customers having equipment or operations that are sensitive to such voltage fluctuations may find it necessary to install, at their own expense, power conditioning equipment or other modifications

Job is to Keep the lights on.

Goals Deliver maximum energy through the existing infrastructure Maintain +/-10% (on average) voltage at service entrance Minimize outages longer than 2-5 minutes 60.00 Hz, when averaged over 24 hours Keep large industrial customers satisfied Minimize large customers disrupting neighbors power quality

10

The utility is responsible for reliability, not quality of power.the customer is responsible for protecting their sensitive equipment at their own expense


Agenda






Power Quality Issues

Voltage sag (dip) and Momentary interruption

High voltage transients (spikes)

Current distortion (harmonics)

Voltage distortion and voltage flicker caused by distorted current loads

Voltage unbalance

Voltage notching

Uncommon issues in the U.S. and high-tech. parks: brownout voltage swell frequency variation

Poor grounding 12

EPRI (Electrical Power Research Institute)

Monitored 300 sites for 2+ years.

92% of all events were voltage sags under 2 seconds

4% of event interruptions from 2 seconds to 10 minutes


Voltage Sag (Dip) Characterization

Sag - RMS voltage reduction between 1/2 cycle - 60 sec

Magnitude and Duration

13

-1

-0.5

0

0.5

1

0 1 2 3 4 5 6 7 8

Duration: 4 Cycles

Magnitude: 60% Remaining


0.0

0.2

0.4

0.6

0.8

1.0

1 10 100 1000

Duration (ms)

Mag

nitu

de (p

er u

nit)

90%

Voltage Sag

14


Why mostly brief sags and interruptions?

" B" " A"

THREE PHASE FAULT

1500kVA480 VOLTS

" C"

F 1

F 2

F 3

1. 0

0. 5

0. 0

TIME

0

VOLTAGE AT "C" AND ON F1 & F3 V=0.67 p.u.

V=0.40 p.u.

20 MVA

BEGINFAULT

F2OPENS

F2CLOSES

F2OPENS

FAULTCLEARS

F2CLOSES

VOLTAGE

VOLTAGE AT "B"

69 kV12 kV

Radial Distribution

Reclosing breakers

V = Vs Zline*I

Fault results in short voltage sags and interruptions for most customers, affecting up to 200 mile radius

15


Why Sag Durations are short

Clearing Time in Cycles Type of Fault

Clearing Device Typical Minimum Typical Time Delay Number of Retries

Expulsion Fuse 0.5 0.5 to 60 None

Current Limiting Fuse 0.25 or less 0.25 to 6 None

Electronic Recloser 3 1 to 30 0 to 4

Oil Circuit Breaker 5 1 to 60 0 to 4

SF6 or Vacuum Breaker 35 1 to 60 0 to 4

Source: IEEE Std 493

16


Sags at High-Tech Mfg. Sites

Very few outages, still many sags!

1000 sag events from 15 Semi plants

Avg. 5.4 events below CBEMA per yearwith transmission-level service!

SEMI F47

source: International SEMATECH & EPRI, 1999


Impact of Voltage Sags

Sensitivity of various 3-ph. 4kW drives to single-phase sag (rated speed, torque) [Djokic]

18


Impact of Voltage Sags

19

AC Relay Voltage Sag Tolerance Curves

0102030405060708090

100

0 50 100 150 200 250 300 350 400 450 500

Duration of Sag (milliseconds)

% o

f Nom

inal

Vol

tage

Upper range Average Lower Range

Source: IEEE Std 1346-1998


Data Corruption

Source: Djokic


IEEE P1668 a new standard

Recommended Practice for Voltage Sag and Interruption Ride-through Testing for End-use Electrical Equipment Less than 1,000 Volts

A standard for the response of electrical equipment to voltage sags

Expected to include: Guidance for evaluation of equipment sensitivity to voltage sags and

interruptions Minimum performance criteria to specify during the purchasing process Levels of performance for acceptance of the product Voltage tolerance curves for three-phase equipment: more useful than CBEMA

or ITIC


Most common effect is equipment drops offline PLC shutdown Open contact or relay (As little as 80% remaining voltage for 1 Cycle)

A secondary effect is that when voltage returns, high current inrush can occur because the Soft-charge circuit is bypassed

RF Amplifiers, Gradient Amplifiers, and Low Voltage Power Supplies subjected to repeated hitsFail.

Voltage SAGS can shut-down and/or damage equipment!

Typical rectifier circuit diagram:

Effect of Voltage Sags on Equipment

22


Voltage Sags Effect Equipment

5

Example: Inrush current measured for 1kVA electronic load

Note the scale change necessary to get the sagged results on the same page!

Normal Inrush Inrush after Sag

Peak inrush 50A Soft-charge

circuit bypassed

Peak inrush 10A Soft-charge

circuit is active

Volts

Amps

10

0

20

Volts

Amps

40

0

23


Only some machines shut down. Why?

L1

:Y Tranf.

L2 L3

Rect.

Controls Power

Machine 1 Machine 2 Machine 3 Machine 4 Machine 5 Machine 6

480-a

480-b

L1 Tranf. N Rect.

Controls Power

L2 Tranf. N Rect.

Controls Power

L3 Tranf. N Rect.

Controls Power

L1 Tranf. L2 Rect.

Controls Power

L2 Tranf. L3 Rect.

Controls Power

L3 Tranf. L1 Rect.

Controls Power

Fabrication or Assembly Line Layout:

Machine power distribution and power supplies vary:


Detection of Power Quality Events

Monitoring is Key to Knowing the Local Power Quality

I-Sense, I-Grid Voltage Monitoring I-Sense voltage monitor device I-Grid network of monitors and database

servers information and notification service

Email & text message notification in real time Web summary, available from anywhere PDF Reports


I-Grid

I-Grid

Servers &

Database

Web

Internet

I-Sense monitors record & report PQ event data via the Internet

Real-time notifications Report delivery

I-Sense Owners

Facility Engineer

Utility Engineer

Other users

Email

Use Web browser to: View event details Manage accounts and monitors Generate reports and export data


Agenda






Sag Correction Solutions

CVT Protection

On-Line UPS Protection

Stand-by UPS Protection DySC Protection

28 28


DySC and UPS Correction Capability

29


UPS Product Offering

30


DySC (Dynamic Sag Corrector)

DySC (pronounced Disk) is an adaptive power supply that optimizes the remaining power during a sag by using patented inverter technology to compensate for the sag thereby maintaining an uninterrupted flow of optimal power to the load thus maximizing uptime, minimizing inventory loss and reducing maintenance costs

MiniDySC (single-phase; 0.25-12 kVA) ProDySC (3-phase; 9-167 kVA) MegaDySC (3-phase; 263-2000 kVA)

Up to 5 seconds of ride through

U.S. and International voltages available

Scalable solution

31


Cross- Coupling

Transformer

Power Conversion

Core

Static Switch

Auto By-Pass

Utility Load

DySC DSP Controller

Rectifier Inverter

DySC - Normal Operation

Normal Operation - The DySC monitors power quality continuously, while the power electronics are in standby 99.99% of the time

Component Activity DSP Controller Constantly monitors incoming power, system integrity and load Static Switch (99% efficient) Closed. Sends power directly to the load Cross-Coupling Transformer Idle Power Conversion Core Idle Automatic By-Pass Idle

32


Power Conversion

Core

Static Switch

Auto By-Pass

Utility Load

DySC DSP Controller

Inverter Cross-

Coupling Transformer

Rectifier

DySC - Voltage Event

Component Activity

DSP Controller Detects the leading edge of a voltage sag, immediately routing power thru the C-C Transformer and Power Conversion Core Static Switch (99% efficient) Open Cross-Coupling Transformer Pulls additional power from the grid Power Conversion Core Rectifies and inverts to recreate a true sinusoidal Output Automatic By-Pass Idle

DySC is On in under 2 milliseconds and recreates a true sinusoidal output 33


DySC Operation

Example: voltage sag to 60%, full load We keep load voltage at 100%,

so load power remains 100% Input Current rises briefly

to (100% / 60%) = 167% Load energy comes from ac input,

not from capacitors!

100%

67%

167%

167%

100%

100%

V = 100% V = 60%

(V = 40%)

LOAD

Normal Operation (Monitoring) Static Switch ON, Highly efficient Power electronics OFF Capacitors charged & ready No thermal cycling, long life Low maintenance Voltage Sag Correction 1-2 millisec. detection Static switch OFF Power Electronics ON, to produce

corrected sinusoidal load voltage Energy from capacitors needed only

for sags below 50%

V = 100%

Static bypass 99.99% of the time

Corrects voltage by maintaining power flow (P = V x I)

Most of the time the DySC is in a monitoring mode

34

patented


DySC Sag Correction

input waveforms

output waveforms

330 kVA MegaDySC responding to 3-phase 50% voltage sag, duration 4.5 seconds

35


DySC Interruption Correction

input rms voltage

output rms voltage

90%

330 kVA MegaDySC-ER

3-phase interruption

for 250 ms (15 cycles)

36


For More Information or Questions

Power Quality at Automation Fair 2012 Essential Components (Booth 127): Protection Solutions

Energy Management (Booth 541): Power Quality Monitoring

Backroom Session: Hands-on DySC and I-Sense / I-Grid More information available at Booths


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Thank you for your attention. Questions?

T-68 Protecting Your Equipment through Power Quality SolutionsAgendaPower Quality vs. Power ReliabilityPower QualityUtility Power Properties of AC GridPower Quality ProblemsAgendaElectrical Equipment Designed Assuming Power QualityImpact of Power Quality EventsConsumer is Responsible for Power QualityAgendaPower Quality IssuesVoltage Sag (Dip) CharacterizationVoltage SagWhy mostly brief sags and interruptions?Why Sag Durations are shortSags at High-Tech Mfg. SitesImpact of Voltage SagsImpact of Voltage SagsData CorruptionIEEE P1668 a new standardEffect of Voltage Sags on EquipmentVoltage Sags Effect EquipmentOnly some machines shut down. Why?Detection of Power Quality EventsI-GridAgendaSag Correction SolutionsDySC and UPS Correction CapabilityUPS Product OfferingDySC (Dynamic Sag Corrector)Slide Number 32Slide Number 33DySC OperationDySC Sag CorrectionDySC Interruption CorrectionFor More Information or QuestionsThank you for your attention. Questions?

t68_protect-equipment-power-quality-solutions.pdf

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