The Generation and Analysis of NonStandard Frequency Components and Even Harmonics in AC Distributio

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The Generation and Analysis of Non-Standard
Frequency Components and Even Harmonics in AC
Distribution Systems

• Presented to the CAPS at FSU
• Presenter Yazhou Liu
• Advisor Prof. Gerald T. Heydt
• Arizona State University, Tempe, AZ
• Electrical Engineering

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Outlines

• Main presentation (25 30 min.)
• The Generation and Analysis of Non-Standard
  Frequency Components and Even Harmonics in AC
  Distribution Systems
• Power Engineering Education (3-5 min.)
• 200 kW Engine Test Stand (3-5 min.)

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Non-Standard Frequency Components

• Power system harmonics
• A sinusoidal component of a periodic wave having
  a frequency that is an integral multiple of the
  fundamental frequency.
• Non-standard frequency components
• They are defined as the non-integer multiples of
  the fundamental frequency components
• Generation of non-standard frequency components
• Integral cycle controllers (ICCs)
  cycloconverters and Kramer drives.

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Non-Standard Frequency Components

• Impact
• Potential shaft damage in drive motors
• Heating effect due to I2R loss
• Voltage distortion
• Loss of life of filters

A typical frequency spectrum of ICC load current
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Scope

• 1 The Impact of Switching Strategies on Power
  Quality for Integral Cycle Controllers, IEEE
  Transactions on Power Delivery, v. 18, No. 3,
  July 2003, pp. 1073 -1078.
• 2 The Power Quality Impact of Cycloconverter
  Control Strategy, IEEE Transactions on Power
  Delivery (submitted).
• 3 A Novel Power Quality Index Asymmetry
  Factor, IEEE Transactions on Power Delivery
  (submitted).

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Integral Cycle Controllers
Switching strategy A switching strategy is
defined as a special sequence of ICC control
signals. The sequence is composed of ones and
zeros where one represents an ON cycle, and zero
represents an OFF cycle. A switching strategy is
represented by d. d 1, 1, 1, 0, 0, 0

• non 3 noff 3 M nonnoff 6
• D 0.5 fd 10Hz fo 60 Hz

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A Mathematical Model of an ICC
Typical waveforms of an ICC with d 1, 1, 0,
1, 0, 0

• The switching control signal m(t) is expressed as
  
• The load current iL(t) is expressed as

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Spectrum Analysis of ICC Load Currents

• The minimum frequency is fd and components occur
  at an integer multiple of the minimum frequency,
  fd fo/M
• No integer harmonics of fo above fo (i.e. no 120
  Hz component)
• The amplitude of fundamental is always
• non / (non noff ), and no phase shift occurs in
  the fundamental (fo) current component
• The amplitude of each frequency component is
  dependent on the switching strategy d

ICC load current frequency spectrum with the
switching strategy d 1, 0, 1, 0, 1, 0, 1, 0,
1, 0, 0, 0
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Power Quality Indices under Non-Standard
Conditions
The THD is expressed in percentage and is defined
as, where k refers to the harmonic order, k
2, 3, 4 , Ik is the amplitude of k order
harmonic, and Io is the power frequency component
(e.g., 60 Hz component).
The THD under non-standard conditions where h
refers to the index number of non-standard
frequency components or harmonics, Ih is the
amplitude of harmonics or non-standard frequency
components.
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Integral Cycle Controllers
Load current THD, power factor, and displacement
factor versus duty cycle D for an ICC with a
resistive load
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Other Power Quality Indices

• Flicker perceptibility
• K-factor
• Telephone influence factor and I?T product

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Flicker Perceptibility of ICCs

• Flicker can be reduced by proper switching
• The worse cases of flicker appear near D 0.5
• Operating with a control window M of an even
  number of cycles, when D is 0.5, the flicker can
  be eliminated completely by on-and-off
  alternating operation
• With more on-and-off alternation, the flicker is
  less for a purely resistive circuit
• The on-and-off switching strategy gives nearly
  optimal results, when the supply inductance is
  high.

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K-factor, TIF and I?T for an example single-phase
ICC
non 4 and noff 3 (resistive load)
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An Innovative Power Quality Analysis - Group
Frequencies

• A group frequency (GF) is defined as a single
  frequency component of a current or voltage
  signal. The component is placed in a given
  frequency band so that the single component has
  the same power quality index (e.g., K-factor) as
  that of all frequency components in the band.

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Sequence Dominant Frequency Band
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Sequence Dominant Frequency Band
Pictorial of sequence dominant frequency bands
A sequence dominant frequency band is defined as
a range of frequencies in which all frequency
components have certain similar sequence
characteristics for example, either the
positive, negative, or zero sequence is dominant.
A sequence dominant frequency band generally
ranges from ( N - 0.5 ) fo to (N 0.5) fo, where
fo is the power frequency and N 0, 1, 2, 3,
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Computation of Group Frequencies
The amplitude of a group frequency can be
expressed as where h is taken over f1 lt f ?
f2. The frequency can be computed using the
equation where KO is the K factor calculated
only over the frequency band O, and fo is the
power frequency where n and m are the maximum
and minimum index in a given frequency band, from
f1 to f2.
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Illustrations
220 V, 10 kW single phase ICC, the switching
strategy d 1, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1,
0. The number of frequency components is
decreased from 56 to 6 in the frequency band (0,
300).
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Cycloconverter
The schematic of a three-phase 3-pulse half-wave
cycloconverter
A cycloconverter is a power electronic device
used to convert constant voltage constant
frequency AC power to adjustable voltage
adjustable frequency AC power without a DC link
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Application of Group Frequencies on
Cycloconverters
Sequence of frequency components of the Phase A
input current of a single-phase bridge
cycloconverter operating at 4 Hz from 60 Hz
supply, 0.8 lagging load (simulation results).
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Even Harmonic

• Generation
• Half-wave rectifiers
• Three-phase half-controlled bridge rectifiers
• Arc furnaces
• Saturated DC-biased transformers
• Loads sensitive to voltage peaks
• Basic single-phase rectifier circuits with a
  large filter capacitor
• Elementary battery chargers
• DC motors

A voltage waveform of a saturated DC biased
transformer
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Waveform Asymmetry
Waveform asymmetry can be caused by even
harmonics or non-standard frequency components
Asymmetry factor (AF)
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Asymmetry Factor (AF)
Pictorial of the impact of m and ? of a second
harmonic on the negative peak voltage Vnp (the
contours in the figure are labeled with the
values of the positive peak voltage Vpp)
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Asymmetry Factor (AF)
Pictorial of the impact of m and ? of a second
harmonic on the negative peak voltage Vnp (the
contours in the figure are labeled with the
values of the negative peak voltage Vnp)
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Asymmetry Factor (AF)
The phase angle difference between the
fundamental and the second harmonic versus
asymmetry factor of a voltage waveform distorted
by 1, 2, 3, 4, or 5 second harmonic
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Asymmetry Factor (AF)
Maximum asymmetry factor versus frequencies of
non-standard frequency components and even
harmonics
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Suggested Limits for Non-Standard Frequency
Components
Suggested current individual harmonic limit for
distribution systems (120 V through 69,000 V,
short circuit ratio lt 20)
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Conclusions

• The power quality impact of ICC switching
  strategies are studies. An optimal switching
  strategy is proposed to minimize flicker.
• An innovative concept, group frequency, is
  proposed. Its application on ICCs and
  cycloconverters are demonstrated.
• A novel power quality index, asymmetry factor, is
  proposed to evaluate the impact of voltage or
  current waveform asymmetry. A limit for
  non-standard frequency components is suggested
  based on the consideration of its poor asymmetry
  factor.

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Connections to the CAPS

• Power quality
• Power quality on ships
• Power electronics
• Cycloconverters propulsion of an electrified
  ship
• Non-standard frequency components
• Impacts on high temperature superconductor (HTS)
  transformers
• 200 kW Engine Test Stand
• A project done in China when I was a mater
  student
• Very similar to a hardware-in-the-loop project

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Power Engineering Education
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U. S. Power Engineering Undergraduate
Enrollments
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U. S. Power Engineering Graduate Enrollments
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A Sample of New Course Offerings

• Power quality
• Power simulation lab
• Alternative energy and dispersed generation
  resources
• Renewable energy systems
• Hybrid electric car

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Main Sources of Funding for Power Engineering
Research

• NSF (National Science Foundation)
• ONR (Office of Naval Research)
• Industries and utilities
• EPRI (Electric Power Research Institute)
• DoE (Department of Energy)

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200 kW Engine Test Stand
China First Automobile Workshop (FAW)
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200 kW Engine Test Stand China First Automobile
Workshop (FAW)
1. What is an Engine Test Stand? 2. Why does it
need to be modernized?
Major function Measuring friction power (power
loss)
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200 kW Engine Test Stand China First Automobile
Workshop (FAW)
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Questions?

• Thank you very much for your time and attention!