School of Engineering and Design Brunel Institute of Power...

School of Engineering and Design

www.brunel.ac.uk/about/acad/sed

Brunel Institute of Power Systems

RESchool 2009

Integration of RES into Distribution Networks

Overcoming Voltage Control Issues

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Agenda

�Distribution networks design and operation

�Distributed generation (RES) in distribution networks

�Voltage control issues

�Coordinated Voltage Control schemes for Active Network Management

�EDF Energy Networks’ case study systems

�Q & A

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Distribution Networks Design and Operation

� Determined by load demand� Fit and Forget principle

� Based on worst case scenario� Predictable load profile

� Static control

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Distribution Networks Design and Operation

http://www.edfenergy.com/powerup/index.html

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Distribution Network with Distributed generation

Connection of DG to distribution networks affects:

� Load flow �From uni-drectional to bi-directional

� Fault level � Increase in fault current�Protection settings

� Losses� Load power factor� Voltage control

�Voltage Rise�Automatic Voltage Control (AVC) Schemes

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Voltage control in Distribution Network with Distributed Generation

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Methods to overcome voltage control rise issue - Theory

( )LG PPR −⋅

( ) ( )V

jQPjXRIjXRV

−⋅+=+=∆

112 V

XQRPVV

++≈

( ) ( )1

12 V

QQXPPRVV LGLG −±⋅+−⋅+≈

� Decreasing R and/or X

� Reducing source voltage V1

� Changing one or both of the terms: ( )LG QQX −±⋅

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Voltage control rise issuefrom Theory to Practice

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� Decreasing R and/or X

�

� Changing

�

� Changing

�

� Reducing source voltage V1

�

�

Voltage control rise issuefrom Theory to Practice

( ) ( )1

12 V

QQXPPRVV LGLG −±⋅+−⋅+≈

( )LG PPR −⋅

( )LG QQX −±⋅

Coordinated Active Voltage Control

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Coordinated Voltage Control schemes for Active Network Management

� Centralized distribution management system

(DMS) control

� Local Voltage Controller

� Advanced Automatic Voltage Control relay

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Centralized distribution management system (DMS) control

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Local Voltage Controller

Key features:

� numbers of RTUs and communication infrastructure

� Distribution State Estimator

Advantages:

� efficient network utilization

� support significant amount of DG

� specific limits for individual nodes

Disadvantages:

� uncertainty in state estimation due to lack of RTUs

� static network model

� significant investment costs

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Advanced AVC relay

Key features:� local measurements

� no need for RTUs – can be employ

Advantages:� increased network ability to accommodate DG

� simplicity of the scheme

� cost effective and easy to installDisadvantages:

� inaccuracies of the estimation technique

� security margin is required � identical voltage limits for whole network

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Case Study Networks

Medium sized town network:� 3 Transformers 30 MVA each� 13 feeders� 5 MW of DG

Rural network:� 2 Transformers 15 MVA each� 3 feeders� 3 MW of DG

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Simulation software

� OCEPS based SuperTAPP n+ simulation software

� Developed at Brunel Institute of Power Systems and EDF Energy Networks

� GenAVC Assessment Tool � Developed by Econnect and EDF Energy

Networks

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Results – Advanced AVC relay SuperTAPP n+

Performance of the SuperTAPP n+ scheme

Voltage target adjustment in SuperTAPP n+ scheme

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Results – Local Voltage Controller GenAVCTM

Voltage Headroom and available generation capacity with GenAVC

Voltage Headroom and available generation capacity for GenAVC with additional RTU

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SuperTAPP n+ Trial

GPRS

SuperTAPP n+

GPRS

iHost

PM710 NX30

CANBUS

NX11

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Summary

� Principles of Distribution Networks design and operation

� Effect of DG in Distribution Networks

� Theoretical considerations of voltage control

� Practical solutions for voltage control in DNs with DG

� Active voltage control schemes for distribution network with distributed generation

� Technical limitations and commercial barriers

� Assessment software for two active network management techniques is presented

� Two case studies based on EDF Energy Networks

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Questions & Answers

THANK YOU

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