INFLUENCE OF FAULTS IN DISTRIBUTION NETWORK ON BEHAVIOR OF ASYNCHRONOUS GENERATORS IN SMALL HYDROELECTRIC POWER PLANTS

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• INFLUENCE OF FAULTS IN DISTRIBUTION NETWORK ON
  BEHAVIOR OF ASYNCHRONOUS GENERATORS IN SMALL
  HYDROELECTRIC POWER PLANTS
• Grega BIZJAK
• University of Ljubljana, Faculty of Electrical
  Engineering - Slovenia

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Introduction

• The number of small Hydroelectric power plants
  (SHPP) in distribution networks in Slovenia
  increase.
• Generators in SHPP react to the disturbances in
  distribution network
• increase in speed
• increase in short circuit power in network
• Digital simulation is an appropriate tool for the
  investigation of such problems in networks.

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Observed distribution network

• 20 kV distribution network with overhead lines.
• More than 50 small hydroelectric power plants
  with mostly asynchronous generators.
• Total power generation of 2000 kW or 45 of the
  load demand.

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Dynamic analysis of the network

• Influence of the faults on the behavior of
  generators in SHPP
• Increase in speed of asynchronous generators
• Influence of the generators on the short-circuit
  current in a network
• Influence on currents and voltages in network
  during the one-phase short-circuit
• Influence on currents and voltages in network
  during the three-phase short-circuit

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Increase in speed of asynchronous generators
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Simulation of three-phase short-circuit
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Conclusions

• During the fault in distribution network, which
  is not cleared fast enough, the asynchronous
  generators may reach the twice of nominal speed.
• Generators have very small influence on
  conditions in the network except on the
  tree-phase short-circuit currents.