Technical Assessment for the Installation of Dispersed Generation in Distribution Networks

1
Technical Assessment for the Installation of
Dispersed Generation in Distribution Networks

• N. Kagan, C.C.B. Oliveira, J.C.B. Silva
• Enerq/University of São Paulo
• C. R. Benedik, A. Conceição
• Elektro Eletricidade e Serviços SA

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Objectives

• Assessing the impact of new DG units in
  Distribution Systems
• Power flow study
• Short circuit study
• Consideration of subtransmission and primary
  distribution networks

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DG units in the Distribution System
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Power Flow Study

• Subtransmission networks
• Newton Raphson Method
• Medium voltage networks
• Radial/three-phase load flow method
• Integration of above methods

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Subtransmission Networks

• - Swing bus (or slack bus) voltage magnitude and
  angle are known (multiple supply busses connected
  the transmission grid).
• - PV or generation bus active power and voltage
  magnitude are known (representing DG units).
• PQ or load bus active and reactive power are
  known.

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Newton Raphson Formulation
Reactive power are then obtained in DG units to
be used as an input to MV network load flow
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Medium Voltage Networks

• Radial networks (usually)

PjQ
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Medium Voltage Networks

• Three-phase modelling
• Load flow is based on ordering network busses and
  branches

Network branch
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Short Circuit Calculations
Complete network
Equivalent network
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Short Circuit Calculations
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Computational System

• Integrated (subtransmission primary
  distribution network) analysis
• Interface with the companys corporative data
  base
• Friendly user interface

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Subtransmission network
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Primary Distribution Network
Network reduction
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Load flow study
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Short circuit study
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Conclusions

• computational tool to evaluate technical aspects
  related to the installation of DG units in
  electric power distribution systems
• DG units in the reduced MV network for
  conventional load flow and short circuit methods
• DG injected power flows are determined for
  different load levels and the MV network is
  analysed in detail by a specifically designed
  three-phase load flow algorithm