Clemson University Electric Power Research Association

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DG VOLTAGE CONTROL IN AN ISLANDING MODE OF
OPERATION
CHANDANA BOMMAREDDY CLEMSON UNIVERSITY
Clemson University Electric Power Research
Association
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Presentation Outline

• Purpose of the presentation
• Distributed Generation and the increasing
  interest in distributed resources
• Grid-connected and stand-alone modes of operation
• Simulation of an IEEE bus feeder using PSCAD
• Simulation of synchronous generator using PSCAD
• Simulation of induction generator using PSCAD
• To study their impact on the voltage in both the
  modes and compare the results
• Conclusion and future work

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Purpose of the Presentation

• Operation of distributed generation systems (DGS)
  in a standalone AC power supply
• Voltage fluctuations due to many reasons
• Distribution networks and voltage stability
• Control voltage and frequency to the improvement
  of the power quality

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Distributed Generation

• Why is Distributed Generation so popular ?
• Speed mobility
• Higher efficiencies than centralized generation
• Reliability of power
• Flexibility choice to consumers
• Reduction of transmission and distribution costs
• Suited for small-scale generation in the
  commercial and industrial sectors

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Distributed Generation Technologies

• Considering only the electrical characteristics
  there are three different DG types
• Synchronous generator
• Asynchronous generator
• Photo Voltaic
• Other

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Different modes of operation
GRID
DG
4.16 / 0.48 kV
LOAD
4.16 kV
480V, 1.5 MW

• Grid-connected mode

The utility is used as reference for voltage and
frequency. DG is assumed to be disconnected from
the grid in this mode of operation.

• Grid and DG connected mode

DG is assumed to be connected and operating in
parallel with the grid in this mode of operation.

• Stand-alone mode

The DG is disconnected from the grid and is its
in maximum mode of operation
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Modeling of power system components

• IEEE 13 Node Test Feeder

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Simulation of synchronous generator
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Simulation of induction generator
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Results and Discussions
Grid-connected mode with and without capacitors
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Synchronous Generator with and without capacitor
Grid and DG mode
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Induction Generator with and without capacitor
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Stand-alone mode
Synchronous Generator
Induction Generator
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CONCLUSIONS

• The steady state models developed, simulate the
  operation of synchronous generator and induction
  generator in the stand-alone and grid-connected
  modes.
• Both the models were used to study the
  comparison of voltage magnitudes in the two
  different modes of operation of the DG.
• Results show the voltage magnitudes dropped
  significantly in the stand-alone mode.
• Capacitors connected at selected buses improved
  the voltage magnitudes by 3 - 6 which is a
  considerable increase.
• Original capacitors in the grid-connected mode
  may not help the islanding mode of operation.

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FUTURE WORK

• Develop the following control mechanisms to
  control the voltage in the stand-alone mode of
  operation at 60 Hz
• Synchronous Condenser
• Static VAR Compensator
• Tap Changing Transformers
• Voltage Regulator
• Other
• Develop detailed models of some DG control
  methods that are described in Part I to control
  harmonics due
• Non linear loads
• DG model

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• QUESTIONS ?
• THANK YOU

Clemson University Electric Power Research
Association