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Interconnecting DERWith Electric PowerSystems
POWER SYSTEM 2002 CONFERENCE-- IMPACT OF DISTRIBUTED GENERATION
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Interconnecting DER with Electric Power Systems
Existing IEEE Standards Standards Coordinating Committee 21:
IEEE Standard 929-2000 Recommended Practice for Utility Interface of Photovoltaic (PV) Systems
Standards Coordinating Committee 23 IEEE Standard 1001-1988 Guide for Interfacing Dispersed Storage and
Generation Facilities with Electric Utility Systems
Current IEEE Standards Work IEEE P-1547 Standard for Interconnecting Distributed Resources with
Electric Power Systems
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Interconnecting DER with Electric Power Systems
Definitions:
POINT OFCOM M ON
COUPLING(PCC)
A
B
C
G
PHASE TOGROUND
PHASE TOPHASE
THREE PHASE
L
LPOINT OF
INTERCONNECTION(PI)
DISTRIBUTEDRESOURCE
DISTRIBUTEDRESOURCE
PCC PCC
Are
a E
PS
Fac
ility
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Interconnecting DER with Electric Power Systems
P-1547 Project Approved in March 1999 4 - 6 meetings of Working Group per year since then Working Group Members
More than 200 names on Working Group Roster 100+ members attend each Working Group Meeting
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Interconnecting DER with Electric Power Systems
Three Official IEEE Balloting Member Categories User
The user is the person who will apply the standard when interconnecting DER to the electric power system. For example, the utility, the DER owner, etc.
Producer The producer is the person who will apply the standard when producing
equipment that will be interconnected to the electric power system. For example, equipment manufacturers, installers, etc.
General Interest The general interest person is one who is interested, but not directly
involved in interconnecting DER to the electric power system. For example, regulatory agencies, financial institutions, advocacy groups, etc.
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Interconnecting DER with Electric Power Systems
Draft 7 circulated for ballot --- closing date of April 1, 2001 Vote Results:
66% Affirmative, not enough for approval (75% required)
VOTE COUNT --- DRAFT 7
Voter Category Affirmative Negative Totals
User 31 23 54
Producer 37 12 49General Interest 30 15 45
Totals 98 50 148
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Draft 8 circulated for ballot -- closing date of October 2, 2001 Vote Results
66% Affirmative, not enough for approval (75% required)
VOTE COUNT --- DRAFT8
Voter Category Affirmative Negative Totals
User 25 33 58
Producer 43 6 49General Interest 35 14 49
Totals 103 53 156
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Interconnecting DER with Electric Utility Systems
IEEE Standard 929 Aimed at Photovoltaic Generator Systems, using solid-state inverters for
interconnection Usually low kilowatt capacity Inverter inherently limits fault current Inverter tends to shut down automatically upon overload or reverse power
IEEE Proposed Standard P-1547 Intended to address DER without regard to prime mover (wind, fuel cell, etc) Attempts to address systems up to 10 Mw in size Seeks to provide ‘universal’ solution
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Interconnecting DER with Electric Power Systems
“User” Concerns Safety of Personnel
Personnel must be able to work on the EPS and DER facility without undue risk of injury or death
General public should not be exposed to hazardous conditions Fault duty, including DER, should not exceed ratings of distribution system
equipment, including customer-owned equipment connected to the system Equipment damage, downed conductors, vault fires, etc.
Normal load-carrying and interrupting capabilities, including DER, should not be exceeded Reduction of system reliability, premature failure of equipment
Protective relaying and control equipment, should not be subject to mis-operation as a result of DER additions More and longer interruptions, high/low voltage problems
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Interconnecting DER with Electric Power Systems
Producer and General Interest Concerns Interconnection costs must be minimal
Interconnection equipment should be some fraction of the cost of the DER being connected.
Utility involvement should be minimized Impact studies cost too much Some utilities use interconnection standards as a means of ‘killing’
DER Interconnection must be ‘simple’ so that it won’t discourage DER applications Interconnection apparatus should be ‘maintenance free’ as much as possible Interconnection operation should be ‘automatic’
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Basic Problem:
Most Utility Electric Power Systems (EPS) were/are not designed to accommodate active generation and energy storage at the distribution level.
Basic Need:
Develop technology and operational concepts that will enable realization of DR benefits while avoiding negative impacts on system reliability and safety
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Significant Problem Areas Scaling
“My typical distribution feeder has a peak load of 4 Mw. Adding a few kW of PV is a whole different problem than adding 400 kW.”
Islanding
Utility is still responsible for voltage and frequency of all its customer connections. Creating an island where some utility customers are supplied with un-controlled voltage or frequency is unacceptable
Safety
Personnel working on the distribution system MUST be protected from backfeed or accidental energization
Protection System Design
Radial distribution line protection is designed and coordinated for ‘one way’ power flow. Bi-directional flow in some part or all of a feeder is a whole new world of problems
Networked Distribution System
Consideration postponed to future updates
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What’s Next? Working Group meeting to discuss ballot results, possible resolution was held
January 30-February 1
Writing Group to meet and attempt to resolve negative ballots received on Draft 8
New Draft of P-1547 to be circulated for ballot before mid-year
Still optimistic on submitting proposed standard to IEEE Standards Board before the end of 2002
