Integrated Environment for the Simulation and Analysis of Power Quality

1
Integrated Environment for the Simulation and
Analysis of Power Quality
University of Puerto Rico Mayagüez Campus

• J. García-Pérez M.
  Mendoza-Sánchez
• E. Olmeda-Berrios C. Ramos-Robles
• Students
• Dr. Efraín ONeill-Carrillo
• Advisor

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Objectives

• Analyze the PQ problems found in the computer and
  machines laboratories of the ECE building in the
  UPR-Mayagüez Campus.
• Model loads and electrical systems using software
  to predict future power quality problems.
• Suggest techniques or methods to reduce or
  mitigate PQ problems in electrical systems.

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Methodology
Literature Review
Analyze Results
Identify Possible Problem Sources
Load Modeling (Software Analysis and Simulations)
Solutions and Recommendations
Theorical and Measured Values Are Equal?
No
Conclusions
Yes
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What is Power Quality?

• Study of power events and disturbances that
  affect the voltage and current waveforms.
• Harmonics, Sags, Swells
• Mitigation of the voltage and current distortions
  and correction of power problems.
• More control in the electrical systems.
• More efficiency in the electrical systems.

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Power Quality Problems

• Transient
• Lightning
• Steady State
• Harmonics
• Sags
• Swells

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Sources of PQ Problems

• Power electronics devices
• Switch-mode power supplies, Non-linear loads.
• IT and office equipment
• Arcing devices
• Large motor starting
• Sensitive equipment
• Storm and environment related damage

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What are Harmonics?

• Periodic sinusoidal distortions of the supply
  voltage or load current caused by non-linear
  loads.
• Increases the r.m.s. values and the reactive
  power, but not the real power.
• The most common tendency of harmonics in a power
  system are the odd (3,5,7,25).
• Could be represented as a Fourier Series.

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What are Sags and Swells?

• Voltage sag is a reduction in the RMS voltage in
  the range of 0.1 to 0.9 p.u. for a duration
  greater than half a main cycle and less than 2
  seconds.
• Caused by events such as large motor starting.
• Voltage swell is and increase in the RMS voltage
  in the range of 1.1 to 1.8 p.u. for a duration
  greater than half a main cycle and less than 2
  seconds.
• Caused by load switching and capacitor switching.

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Measuring Equipment

• Fluke 43
• PQ Analyzer
• Graphs signal waveform
• Capture harmonic distortion
• Calculate THD

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Measured Data
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Measured Data
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Load Modeling

• Generic non-linear load model.
• Empirical Model.
• Simple RLC circuit, plus a harmonic current
  source.
• Variables v(t) and i(t) are known or measured
  quantities.

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Load Modeling
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Simulations
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Recommendations

• Utilize delta-delta and wye-delta transformers to
  reduce harmonics.
• Modify the system frequency. Adding or removing
  capacitor banks and adding shunt filters.
• Filter harmonics at the load or on the system
  with shunt filters.

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Recommendations

• Verify grounding connections in the electrical
  system.
• Isolate the loads using transformers or UPS
  systems.
• Add voltage regulators .