Improving  Interconnec.on:    Integrated  Distribu.on  Planning

Sky  C.  Stanfield  

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 What  is  the  Problem?      

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Successful  promo.on  of  renewable  resources  increased  na.onwide  interconnec.ons  to  over  90,000  PV  systems  in  2012.    That  number  is  predicted  to  rise  to  150,000  PV  systems  in  2015.    The  number  of  interconnec.on  requests  is  much  higher.    Current  interconnec.on  procedures  are  largely  reac.ve  

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Es'mated  Hos'ng  Capacity  of  Circuit  Based  

on  Customer  Load*  

Installed  DG  Capacity  

DG  Penetra.on  Compared  to  Es.mated  Hos.ng  Capacity  

Penetra'on  Level  

*  The  two  most  common  es'mates  of  hos'ng  capacity  based  on  customer  load  are  15%  of  peak  load  and  100%  of  minimum  load.  

Solar’s  Success  Also    Means  Higher  Penetra.ons  On  U.lity  Distribu.on  Systems  

 

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Over  20%  of  distribu'on  circuits  in  Hawaii  were  over  15%  of  peak  load  in  January  2013.      Pepco  has  closed  a  number  of  its  distribu'on  system  feeders  to  further  DG  development  because  of  high  penetra'ons.    

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Some  states  and  u'li'es  are  taking  significant  steps  to  bePer  integrate  high  penetra'ons  of  PV  into  u'lity  

distribu'on  systems.  

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 A  Possible  Par.al  Solu.on:  Proac.ve,  Integrated  Distribu.on  Planning      

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Summary  of  Integrated  Distribu.on  Planning  

• IDP  Proac'vely  plans  distribu'on  systems  to  accommodate  DG  before  interconnec'on  screens  are  applied.      

• IDP  informs  the  processing  of  subsequent  interconnec.on  requests  by  determining  in  advance  the  level  of  penetra'on  that  can  be  accommodated  without  impacts.      

• For  higher  penetra'on  levels,  IDP  gives  a  u.lity    advanced  knowledge  of  the  upgrades  that  may  be  required  to  maintain  safety,  reliability  and  power  quality.    

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Forecast  DG  Growth  on  the  Circuit  

Establish  the  Hos'ng  Capacity  and    Allowable  Penetra'on  Level  

Determine  Available  Capacity  on  the  Distribu'on  Circuit  

Plan  Upgrades  and  Expedite  Interconnec'on  Procedures  Based  on  IDP  

Publish  the  Results  

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The  5  Steps  of  IDP  

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Forecast  DG  Growth  on  the  Circuit  1  

U'li'es  can  focus  on  circuits  where  significant  addi'onal  DG  development  is  likely,  i.e.,  establish  a  trigger  point  for  IDP  study  such  as  when  DG  capacity  surpasses  15%  of  peak  load.    A  reasonable  forecast  of  incremental  DG  could  include  the  exis'ng  interconnec'on  queue  plus  a  reasonable  predic'on  of  growth  based  on  market  condi'ons  and  policy  mo'va'ons.    

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Establish  the  Hos.ng  Capacity  and    Allowable  Penetra.on  Level  2

Many  factors  affect  hos.ng  capacity,  including  circuit  characteris'cs  and  the  size,  loca'on  and  type  of  generators.  Need  for  detailed,  accurate  models.    Proac've  circuit  study  can  iden.fy  circuit  characteris.cs  that  may  need  to  be  modified  if  forecasted  levels  of  DG  growth  materialize.        Such  iden'fica'on  will  allow  u'li'es  to  make  an  es.mate  of  hos.ng  capacity,  which  reveals  an  allowable  penetra.on  level,  i.e.,  the  maximum  amount  of  genera'on  of  a  certain  type  and  size  that  can  be  interconnected  in  a  certain  area  with  confidence  that  system  impacts  are  unlikely.  

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Determine  Available  Capacity  on  the  Distribu.on  Circuit  3

Hos'ng  Capacity  

Forecasted  Genera'on  

Exis'ng  Genera'on  

Available  Capacity  

Current  Penetra'on  Level  

Capacity  is  available  –  and  upgrades  are  not  needed  –    when  forecasted  genera.on    is  less  than  infrastructure’s    hos.ng  capacity.      Available  capacity  may  need  to  be  differen'ated  by  generator  types,  sizes  and  loca'ons.    

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Plan  Upgrades  and  Expedite  Interconnec.on  Procedures  Based  on  IDP  4

When  forecasted  genera.on  exceeds  infrastructure’s  hos.ng  capacity,  the  u'lity  can  iden'fy  the  technical  factors  limi'ng  DG  development  and  determine  whether  a  minor  or  major  upgrade  is  needed.  

Forecasted  Genera'on  

Exis'ng  Genera'on  

Hos'ng  Capacity  

Poten'al  Infrastructure  Investments  

Current  Penetra'on  Level  

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Iden'fying  technical  factors  limi'ng  DG  expansion  can  be  used  two  ways:    1.  On  an  aggregate  level,  it  can  give  the  u'lity  the  opportunity  to  

iden.fy  and  priori.ze  the  possible  upgrades  to  distribu.on  infrastructure  that  would  be  required  to  accommodate  an'cipated  DG  growth.      

2.  It  can  be  used  on  a  project-­‐by-­‐project  basis  to  inform  the  interconnec.on  screens  and  procedures  that  are  applied  to  each  facility  individually.    

Plan  Upgrades  and  Expedite  Interconnec.on  Procedures  Based  on  IDP  4

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Publish  the  Results  5

Ideally,  a  u'lity  will  publish:    •  Es'mated  hos'ng  capacity  and  allowable  penetra'on  levels  

 •  The  loca'on  and  'ming  of  any  planned  upgrades      

THANKS to our generous sponsors for the 2013 3iForum and 3iAwards

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For  more,  see  the  full  paper:  Integrated  Distribu'on  Planning:  A  Proac've  Approach  for  Accommoda'ng  High  Penetra'ons  of  Distributed  Genera'on  Resources,  by  Tim  Lindl  and  Kevin  Fox,  IREC;  Abraham  Ellis  and  Robert  Broderick,  Sandia  Na'onal  Lab  

Thanks  to  Tim  Lindl  for  the  generous  use  of  his  presenta.on  slides  

 Sky Stanfield

Keyes, Fox & Wiedman LLP (510) 314-8204

sstanfield@kfwlaw.com