3.1 - anti-islanding protection for small generation in ontario - aidan foss
TRANSCRIPT
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Anti-Islanding Protection for Small Generation in Ontario
Aidan FossANF Energy Solutions Inc.
NRCanNRCan DER InterconnectionDER InterconnectionPeer Review MeetingPeer Review Meeting
2525thth February 2008February 2008
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Anti-Islanding Protection
Anti-islanding protection has been found to be a major barrier to the connection of small (<500kW) generation to rural feeders in Ontario
• Above 50% of the minimum feeder load, the general utility requirement is for Transfer trip
• Cost of Transfer trip ($150K-$250K) can be a show stopper
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
•Generation on feeder shared with other customers•Recloser/switch normally closed•Utility feeder protection may open recloser/switch
DISTRIBUTEDGENERATION
OTHER CUSTOMERS
THEGRID
RECLOSER
VUTILITY FEEDER
The Elephant and the Mouse (1)
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
•Feeder energized by your voltage•Other customers supplied with your voltage•Need to disconnect as fast as possible, and before …
DISTRIBUTEDGENERATION
OTHER CUSTOMERS
THEGRID
HYDROPOWER
CUT
VVUTILITY FEEDER
The Elephant and the Mouse (2)
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
•Grid voltage wins over your voltage•Grid voltage wave travels into feeder•Risk of generator torque shock and other damage
DISTRIBUTEDGENERATION
OTHER CUSTOMERS
THEGRID
HYDROPOWER
RESTORED
V V
UTILITY FEEDER
The Elephant and the Mouse (3)
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Current Standards Local Utility Requirement
Disconnect time
<50% Minimum Feeder Load
U/O frequencyU/O voltage
Power Export
>50% Minimum Feeder Load
< 2 sec.(IEEE 1547, CSA C22.3
No. 9)
Varies, but can be< 1 sec.
Fast transfer-trip : $150k - $250kShow stopper for small DG!
Transfer-trip or Alternative : $30k - $50k?
Protection Standards
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Terryland Farms Experience
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Grid Connection
HV FUSE
GENERATORPROTECTION
INTER-TIE CIRCUIT-BREAKERINTER-TIEPROTECTION
GENERATOR CIRCUIT-BREAKER
TO DIGESTER & POWERHOUSE LOADS
8.3KV / 480V300kVA Yg:Yg
M REVENUE METER
BIOGAS GENERATOR180kW 480V
UTILITY FEEDER 8.3kV
HV DISCONNECT
LV DISCONNECT
LV FUSE
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
TERRYLAND180kW
PINEHEDGE100kW
RECLOSERS
8.3 kV
STARDALE DS44 / 8.3kV
8.3 kV
))) (((
))) (((TRANSFER TRIP SYSTEM
INITIALLY RERQUIRED BY UTILITY
• Terryland Farm > 50% MFL• Pinehedge Farm < 50% MFL
MINIMUM FEEDER LOAD
~ 240kW
Local Distribution Network
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Pole Mounted Reclosers
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Anti-Islanding Considerations
• Transfer-trip too expensive – show stopper• Approached NRCan for assistance• Looked for site-specific knowledge that can be used for
proposing an alternative?
• Increasing recloser times / bypassing reclosers – not an option
• Moving reclosers – expensive, did not solve• Voltage blocking – not feasible for pole mounted
reclosers• Rural feeder characteristics?
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• Rural feeder load is inductive• Generator set-point to import VArs from the Grid• Loss of the Grid Shortage of reactive power on the feeder
Generator exports VArs• A directional reactive power relay is used to detect and trip
on a change in VAr flow• Tight conventional protections used as back-up
VAr TripLevel
VArSet-point
P
Q
Proposed Anti-Islanding Concept
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• Multi functional generator protection relay (18 protections)
• 40Q: directional reactive power protection connected in reverse
Off-the-Shelf Relay
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• Computer model development, verification and tuning:– Load rejection and load pick-up tests
• Dynamic analysis of various scenarios:– +50%, +25% & 0% power mismatch
• Field verification:– Islanding detection and disconnection time tests
– Nuisance tripping tests
Validation Test Plan
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Simulation Results: 25% mismatch• Load: 245 kW,
pf=0.95 lag• DG: P=+180 kW,
Q=-31 kVAr• Islanding: t=20s
ΔV = 25% drop,Δf = ± 1 HzΔQ = -31 → +80
1 9 .5 2 0 2 0 .5 2 1 2 1 .5 2 25 9
6 0
a) f
(Hz)
1 9 .5 2 0 2 0 .5 2 1 2 1 .5 2 2
0 .8
1
b) V
(p.u
.)1 9 .5 2 0 2 0 .5 2 1 2 1 .5 2 2
0 .1 5
0 .2
0 .2 5
c) P
(MW
)
1 9 .5 2 0 2 0 .5 2 1 2 1 .5 2 2-0 .0 5
0
0 .0 5
0 .1
d) Q
(MV
Ar)
1 9 .5 2 0 2 0 .5 2 1 2 1 .5 2 2
0 .1 5
0 .2
0 .2 5
Time (sec)
e) P
(MW
)
DG bus
DG
DG
Load
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
19.5 20 20.5 21 21.5 2260
60.5
a) f
(Hz)
19.5 20 20.5 21 21.5 220.85
0.90.95
11.05
b) V
(p.u
.)19.5 20 20.5 21 21.5 22
0.15
0.2
c) P
(MW
)
19.5 20 20.5 21 21.5 22
-0.04
-0.020
0.02d)
Q (M
VAr)
19.5 20 20.5 21 21.5 22
0.14
0.16
0.18
Time (sec)
e) P
(MW
)
DG
DG
Load
DG bus
• Load: 180 kW,pf=1
• DG: P=+180 kW,Q=-31 kVAr
• Islanding: t=20s
ΔV = 15% drop,Δf = + 0.5 HzΔQ = -31 → +10
Simulation Results: 0% mismatch
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Directional Reactive
Power Relay
Utility GridRepresentation
DG
Load 1
Load 2
Farm load
PCC
P
Q
•Soft Start to reduce motor transients•VARs measured at generator breaker, but trips inter-tie breaker
Field Test Configuration
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Measurement and monitoring devices
Biogas Engine-Generator
Currentfeedback
Field Test Facility
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Relay
GridCB
Gen.Current(Inter-tie CB)
Gen.Voltage 0.136 s 0.216 s
Gen= 72-kW, Load = 95-kW, pf=1 (33% mismatch)
Islanding Test 1: Dynamics
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Gen= 130-kW, Load = 145-kW, Q=37-kVAr
0.173 s
0.230 sGridCB
Relay
Gen.Current
±0.5HzFreq. setfor Gen.
Islanding Test 2: 10% Mismatch
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• System commissioned August 2007• Scheme Implemented as logical AND of kW and kVAr limits• Nuisance trip tests - large motor load starting transient• Significant imbalance – move to 3-phase kVAr measurement
-15
-10
-5
0
5
10
15
20
25
30
35
0 20 40 60 80 100 120 140 160 180 200
kVA
r
Phase APhase BPhase C3-Ph Q
Time (sec.)
Reactive power variations of the Generator (t1: Agitator start-up, Aug. 23, 2007 - 16:05:59)
Trip set-point (40Q relay)
Commissioning
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• For all tests, the trip time was less than 0.25 s• Working with the utility as a potential generic
solution for small DG (<500 kW)• Applicable to feeders with inductive load
characteristics• No nuisance trips during commissioning (soft start
on 15-kW agitator motor) but potentially sensitive to motor starting transients
Terryland Summary
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
CETC-V, ANF Energy Solutions, Genesys, Terryland Farm
Joint Effort to Test the Method
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
FEPRO FARMS 499kW
12.47kV
3 x 1-PHASE RECLOSERS
BEECHBURG DS44kV / 12.47kV
MINIMUM FEEDER LOAD
~ 500kVA
Fepro Farms Application
450 kVAr
12.47KV / 600V750kVA Yg:Yg
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Anti-Islanding Considerations
• Utility: “will be working with the Generator on developing an alternative to Transfer Trip”
• Capacitor banks on the feeder – feeder not inductive at light loads – cannot apply Terryland method
• Recloser time – 2 seconds – suggested that slower transfer trip may be best option
• Experience from other areas of low-cost uni-directional fail-safe transfer trip
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Uni-directional Transfer Trip
3 x 1-PHASE RECLOSERS
& WIRELESSINTERFACE
RECLOSERSTATUSES
))) ((( ))) (((
INTER-TIEPROTECTION
INTER-TIECIRCUIT
BREAKER
WIRELESSINTERFACE
Trip the inter-tie breaker if• Any recloser is open• Loss of communication
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Old Reclosers
• Substation reclosers are old – do not have status indication
• Replacing reclosers is expensive ($100K+)
• Pulse-based method – demonstrator proposed for an alternate site
• CT-based method – proposed to utility for this site• Response from utility: “Appears to be conceptually OK”• Limited nuisance tripping is OK if this avoids transfer trip
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
CT-based Proposal3 x 1-PHASE RECLOSERS
RELAY
WIRELESSINTERFACE
))) ((( ))) (((
INTER-TIEPROTECTION
INTER-TIECIRCUIT
BREAKER
WIRELESSINTERFACE
Trip the inter-tie breaker if• Over-current (within recloser setting)• Low current on all three phases• Loss of communication
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
Low Current Trip
Trip for low current on any single phase• Safe• Potential for high incidence of nuisance tripping due to
current imbalance
Trip for low current on all three phases• Low expected incidence of nuisance tipping• Preliminary studies show little voltage phase angle
difference across a single open phase low damage potential
• Further studies required (Work in progress)
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NRCan Peer Review25th March 2008ANF Energy Solutions Inc
Anti-Islanding for SmallGeneration in Ontario
• Key limitations are the presence of the capacitor bank and the type of recloser
• Need to avoid recloser replacement to have an affordable scheme
• Low-cost wireless components are available• Further studies and equipment selection
required
Fepro Summary