Optimal Location of Distributed Generation Units on Radial Distribution Feeders

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Electrical and Computer Engineering
Department University of Puerto Rico-Mayagüez

• Optimal Location of Distributed Generation Units
  on Radial Distribution Feeders

Angel A. Aquino Lugo Atzel S. Santiago Cruz José
R. Cedeño Maldonado
POWER ENGINEERING _at_ UPRM Energizing the Future
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Overview of Distributed Generation Presentation
1. Central Distribution
2. Distributed Generation
4. Research in Distributed Generation

• 3. DG Technologies

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The present power system follows a conventional
structure
Back-up
Load
Transmission
Distribution

• 200 hours per year limit
• Exempt from emissions regulations
• Not interconnected
• Does not support the grid but operates after the
  grid has failed

• 100,000 /mile
• 6-7 electric losses
• Difficult to obtain right-of-ways

• 400-500/KW
• Difficult to permit

Generation
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Vulnerabilities of Conventional Power Systems

• High power losses
• Service Reliability
• Quality of Service
• Permits for construction of infrastructure
• Environmental impacts and emissions

New York City during the blackout of August 14,
2003
Cars stopped at a ride at Cedar Point Amusement
Park in Ohio. Riders were stranded on the roller
coaster for 20 minutes.
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Distributed Generation (DG) Definition

• Small-scale generation that provides electric
  power at or near the load site
• Interconnected to the utility distribution system
  and/or directly to the customers facilities
• Typically 10MW capacity or less

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DG Potential Benefits

• Sitting of DG at or near end-use locations will
  provide the following important advantages.
• Increase local and/or system-wide utility service
  reliability.
• Reduce transmission and distribution line losses
• Reduce environmental impacts and emissions.
• Provide new utility products and services.

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DG Limitations Considerations

• Low Voltage profile if DG is placed near
  transformer bus.
• Voltage flicker noticeable to customers.
• Introduction of harmonics cause by power
  converter on interconnection point.
• DG can alter the short circuit levels causing
  fuse-breaker miscoordination.
• Voltage swells and overvoltages.

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DG Technologies
Wind Turbines
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Research Objectives

• Determine the impact of Distributed Generation on
  actual power systems
• Determine the best location of distributed
  generators so that the real power losses on the
  distribution network is obtained
• The best location of distributed generators so
  that an optimum voltage profile on the
  distribution network is obtained

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Power Losses

• DG units will impact both the real and reactive
  power flow.
• The addition of DG units may cause an increase in
  power losses.
• Finding the best location where power losses are
  minimized counteract the previous problem.

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Voltage Profile

• Different techniques are used to maintain the
  voltage magnitude at the load within specified
  limits.
• Distributed Generation introduces meshed power
  flows that interfere with the effectiveness of
  standard voltage regulation practice.
• With DG weaker feeders that have a very low
  voltage level will benefit from an increased
  voltage level.

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22 bus test feeder system

• SKM Power Tools simulation (PTW32)
• Based on a 22 buses test feeder configuration
• Simulation using trial and error on each bus to
  find the best voltage profile and to minimize
  losses.

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22 Bus feeder

• DG installation impact modeled
• Nodal voltage and losses recorded
• The further the DG unit was placed from utility
  the better the results
• DG at Node 22 provides the best results

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22 Bus feeder
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22 Bus feeder
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28 bus test feeder system

• SKM Power Tools simulation (PTW32)
• Based on a 28 buses test feeder configuration
• Same methodology as on the previous feeder

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28 Bus feeder

• DG installation impact modeled
• Nodal voltage and losses recorded
• Results are similar to those obtained on the 22
  buses feeder
• Placing the DG unit further from the utility
  yielded better results
• DG at Node 26 provides the best results

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28 Bus feeder
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28 Bus feeder
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Research Conclusions

• The best location for distributed generation
  units so that an optimum voltage profile in the
  distribution network is obtained depends on the
  complexity and shape of the system.
• For a balanced system the farther the generator
  is located from the utility the better the
  improvement in voltage profile.
• The losses will also be minimized at that
  location.
• Varying the location of the generator has an
  impact on the system.

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Conclusion Distributed Generation

• DG provides benefits to the system
• DG still has limitations that must be addressed
• DG a relatively new technology with many research
  opportunities
• DG is the future for power generation.

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• QUESTIONS???