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How to Explain Our- Side-of-the-Meter Topics to Customers More

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How to Explain OurSide-of-the-Meter
Topics to Customers
More Effectively
Topic #1:
Power Factor Correction & Costs
Topic #2:
Why Utilities Have Interconnect Rules for Solar &
Wind Power
Topic #3:
Dealing With Power Quality “Offenders” Affecting
Other Customers
Managing Power Factor (p.f.)
• What is it?
– Ratio of real power to apparent power used in an AC
power system
• Causes of low power factor
– Motors, fluorescent lights .anything with coils of wire
and many electronic devices.
• Why does the utility care?
– Bad things can happen economically and physically if
p.f. is not managed and controlled
• Power factor improvement options
– Generation modification, Capacitors, VAR
Compensators
Electrical Power
• The rate of work that can be accomplished.
• There are 3 Types of Electric Power
– Real Power (Watts, Kilowatts (kW), Megawatts (MW))
– Apparent Power (Volt-Amps, Kilovolt-Amps (kVA),
Megavolt-Amps (MVA))
– Reactive Power (Volt-Amps, Kilovolt-Amps Reactive
(kVAR), Megavolt-Amps Reactive (MVAR))
• Apparent Power = Real Power + Reactive Power
– Kind of……..Using Vectors/Vector Math
and Trigonometry.
Real Power (kW)
What is Power Factor?
• Ratio of Real to
Apparent Power in a
circuit
• Given as % or
decimal equivalent
• Circuit with 90%
(0.9) power factor;
100% Power Factor
Voltage
Current
Time
No Lag
– 90% is real (kW)
– 10% is reactive
(kVARs)
• Indication of the
timing between the
volts and amps in an
AC system.
Power Factor < 100%
Voltage
Current
Time
Lag
What Causes Low Power Factor?
• Inductive Loads….things with coils of
wire inside using magnetic fields to
operate.
– Motors
• Motor oversizing; oversized motors
have low power factor
• Lots of small motors; small motors
tend to have low power factor
– Fluorescent lights
• High efficient lighting ballasts can have
high or low power factor depending on
the quality
– Solenoid operated equipment
• Operations with lots of these devices
that operate for long periods can
have low power factor.
Why Do Power Suppliers Care
• Economics
– Match revenue and costs
more closely by customer
• Some customers may have
power factor penalties and
some may not.
– Reduce power/line losses in
the distribution system
• Reliability
– Improve voltage regulation
due to reduced line
loss/voltage drop
What is the potential impact to the
company if you don’t measure all the
power each customer uses???????
Why Is This So Confusing?
• Power factor causes a disconnect
between our billing and equipment
sizing jargon.
• Most people don’t like vector math.
• Real Power (kW or MW) is used as a
billing term
– Induction meters ($12) can only
measure real power
– Historically needed multiple meters and
$$$$$$$$$ to measure apparent power
• Apparent Power (kVA or MVA) is used
as an equipment sizing term
– The transformer and components must
be sized large enough to handle ALL the
power going through it….or it will fail.
– It makes sense to size the equipment
for the total (apparent power) and not
just the real or the reactive part that
makes it up.
Analogies People Use
• In an attempt to
explain power
factor people use
all kinds of
different analogies
Apparent Power (kVA)
– Pulling Wagon
– Sailboats
– Beer & Foam
– Water Wheel
Reactive Power (kVAR)
Real Power (kW)
But What Is It??????
• Deviation in the timing of
the change of direction
between the volts and
amps in an AC electrical
system having coiled wires
(motors and fluorescent
lights).
• The magnetic field
produced in a coil of wire
(motor windings,
fluorescent ballasts)
causes the current (amps)
to slow down in relation
to the pressure (volts) in
an AC electrical system.
100% Power Factor
Voltage
Current
Time
No Lag
Power Factor < 100%
Voltage
Current
Time
Lag
Power Factor Improvement/Correction
• Need to speed the electrons/amps back
up in relation to the voltage.
• Electron Speeder Uppers (technical term)
otherwise known as Power Factor
Correction
– Generation….Some generators can be
“adjusted” to produce slightly more or less real
and reactive power
– Transmission….Capacitor banks can be added
to the transmission system by the owner.
– Distribution…..Capacitor banks can be added
to the distribution system by the owner
– Customer……Capacitors and/or VAR
compensators can be added to the electrical
system by the customer.
Economics of Power Factor Correction
• What charges/penalties do I pay the
power supplier for low p.f.?
• What does it cost me in equipment
and installation cost to correct?
• How fast do I break even?
• What are the other benefits I may
receive?
– Power Supplier
• Better voltage regulation and reliability
• Lower line losses that can save money
– Customer
• Better voltage
• Cooler motors that run longer
• Cooler lighting systems that last longer
How to Explain
Our-Side-of-theMeter Topics to
Customers More
Effectively
Topic #1:
Power Factor Correction & Costs
Topic #2:
Why Utilities Have Interconnect Rules for Solar &
Wind Power
Why We Have Interconnection Rules & Procedures
(Helping consumers understand)
The highway system for
vehicles
1.
The “electric
highway” system (grid)
2.
Rural Electricity Resource Council
Wilmington, Ohio
Any system with more than one user, needs rules.
Traffic laws for
the highway
Interconnection
rules for the grid
This protects the system
for everyone.
“Rules of the Road”
(transmission vs. distribution)
Some paths are large to
handle large volume of
cars.
Others are small to
handle a lesser
flow.
Same with grid and flow
of electricity.
“Rules of the Road”
Traffic needs to flow one way on some paths,
and the opposite way on other paths.
Electric Transmission & Distribution Large Lines and Smaller Lines
Power plants:
the "heart" of
the system.
“Rules of the Road”
To “connect” there are
required ways to enter and exit.
For highway:
Must also use safe methods
to “connect”.
For grid:
Inverter
Wind Disconnect
Wind Service
Energy Panel
Meter
How to Explain OurSide-of-the-Meter
Topics to Customers
More Effectively
Topic #1:
Power Factor Correction & Costs
Topic #2:
Why Utilities Have Interconnect Rules for Solar &
Wind Power
Topic #3:
Dealing With Power Quality “Offenders” Affecting
Other Customers
Sometimes customers need help understanding power
suppliers don’t and can’t provide perfect power
Caught in the Middle
• What happens when one
customer causes
electrical problems for
another customer?
• The power supplier is
caught in the middle.
• Power quality
disturbances can be very
short in time….but cause
all kinds of operational
problems with electronic
equipment.
Is this a “grounded service”
Neighbor As Source
• The utility distribution system
can simply provide a path for a
problem at one location to
move and show up at another
location.
• Common power quality
problems originating at a
neighboring customer location
include:
– Phase Voltage Unbalance
– Voltage sags from startup of large
inductive loads
– Waveform distortion including
harmonics and line notching.
– Excessive neutral to earth voltage
from high neutral current
flow/faults returning to the utility
system from improperly grounded
equipment.
SERVICE 1
FAULT CURRENT
NEIGHBORING
SERVICE
SERVICE 2
FAULT CURRENT
FAULTY WATER PUMP
Short Term Voltage Fluctuations
(Sags, Swells & Flicker)
• Sag
Voltage Sag
(+)
Less than 1 minute
Voltage
– Voltage falls between 10 and
90% of nominal
• Swell
• If it’s long enough, you
notice lights dimming or
getting brighter.
• Sags are much more
common than swells
(-)
Time
Voltage Swell
(+)
Less than 1 minute
Voltage
– Voltage rises to between
110% and 180% of nominal
(-)
Time
Swell Trip Example
• A gas processor is complaining to the power supplier about frequent
tripping of a compressor motor.
– The facility had recently undergone an equipment upgrade where electronic
control and protection equipment replaced traditional protection equipment.
• The compressor might trip off 3 or 4 times a day or go several days
without a trip.
– Monitoring at the power supply point showed numerous short term swell
events on the electrical system caused by a neighboring customer starting a
large motor.
– When contacted for assistance, the electronic control equipment
representative indicated the trip adjustments should not be modified because
the motor would not be protected “as well”.
Power Quality Monitoring
The Solution
• Voltage varies outside of ANSI C84.1 (normal) levels for
fractions of a second….not seconds or minutes.
– Current power supplier standards really don’t address this well.
• Adjust the trip settings on the new electronic controls from
their extremely sensitive factory settings to more
reasonable settings seen in the “real world”.
– The factory trip setting was + 5% for any length of time longer
than 6 cycles (0.1 second).
– Motor standards allow + 10% continuously.
• Changing the settings to + 10% for 5 seconds (max) allowed
the equipment to ride through the “events” caused by the
neighbor that were considered “unusual” but within the
realm of “normal” operation.
Transients (Spikes)
• Distribution System
• Breakers
• Capacitors &
Transformers
Impulsive Transient
(+)
Voltage
– Lightning
– Switching Operations
– Fault Clearing/Breaker
Operations
• Customer System
– Lightning
– Arcing Devices
– Starting & Stopping
Motors
– Breaker Operations
– Capacitor Switching
(-)
Time (seconds)
Transient Example
• A small machine shop is complaining
to the power supplier about spikes
measured at the meter coming from
the distribution system.
• A VFD manufacturer has replaced the
same 250 Hp drive three times in the
last year and has finally said “no
more drives under warranty”.
– Each failure is a problem with the
electronics on the circuit boards
exhibiting classic signs of overheating
from “spikes” according to the drive
manufacturer.
• Monitoring by the drive company
shows an occasional 3,000 volt
transient that occurs from very few
to thousands of times a day coming
in at the service.
The Problem/Solution
• A welding shop ¼ mile down the road has an
automatic welding process they occasionally run.
– When the welding machine strikes an arc, a high voltage
transient is created that propagates along the
distribution system.
– They also have a grounding problem.
• The Solution:
– The shop experiencing the problem added Transient
Voltage Surge Suppression at the service and the
problem with the drives disappeared.
Waveform Distortion
• A steady state deviation
from an ideal sine wave of
power frequency principally
characterized by the spectral
content of the deviation.
• There are several types of
waveform distortion:
– Harmonic Distortion
– Line Notching
– Noise
– Frequency Fluctuations
• The most “discussed” of
these in the recent past is
Harmonic Distortion.
1990’s Harmonic Enforcement Example
• A power supplier is getting multiple
complaints from residential customers
in rural areas near oil company
installations of submersible pumps
operated by VFD’s
– Electronic equipment exhibits multiple
operation problems and resets/reboots
frequently.
– Equipment manufacturers says the
equipment is working fine when brought in
and checked at the shop.
– Checks by the utility show large amounts of
harmonic distortion exceeding IEEE 519
standards levels on the utility system.
– Customers are also complaining about
frequent static on the rural phone system to
the extent the phone is un-usable.
The Solution
• The power supplier manager writes a
letter to the oil companies (5 largest
revenue customers) and politely asks
them to add filters to their VFD
installations to eliminate the
harmonics on the system.
– The oil companies supply diesel
generators and diesel to the
neighboring customers in an attempt
to get everyone off their back.
– The FCC eventually steps in and tells
the utility manager “shut them off to
clean up the phone system”.
– A judge sides with the FCC when the
utility manager hesitates.
– The oil companies install the necessary
filters on their drives after a couple of
years of everyone being frustrated.
2000’s Enforcement Example
• Harmonics produced by VFD’s in a
chemical plant in NM are causing
occasional shutdowns of
automatic oilers on a natural gas
compression station down the
road.
• The utility measures THD in excess
of IEEE 519 standards and
immediately tells plant
management they cannot operate
their VFD’s until they can comply.
• The chemical plant loses several
hundred thousand dollars in
revenue during the shutdown
waiting for filters to be installed
on the drives so they can
commence operation.
2010’s Enforcement Example
• A major oil companies variable
frequency drives are causing a
harmonics problem for a
neighbor....a large natural gas
pipeline.
– The automatic oiling devices on the
pipeline compressor trip off and
shut down the pipeline compressor
adversely impacting pressure on the
pipeline.
• The oil company has been a
consistent source of harmonic
distortion in the past that is causing
problems for the power suppliers
AMR system.
– The power supplier must schedule
shutdowns of the customer’s
equipment before the AMR system
will read the meters on that
distribution line.
The Solution
• The power supplier manager has been told by state
officials shutting the offending company off until
compliance is gained would not be acceptable.
• The power supplier manager places a large switch at
the offending customers service that monitors
harmonics produced by the customer and disconnects
the service “temporarily” to protect the neighboring
customers equipment.
• The closest service center is 40 miles away and a
“reconnect fee” is charged each time the power
supplier must reconnect the switch to restore power.
• The switch opens 12 times in the first week…..the
customer decides to fix the problem.
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