1. Forum – 19 June 2014
Planning Inner Sydney’s Electricity Future Forum 1
Thursday, 19 June 2014

2. Forum Summary
The form held on the 19 June, brought together a range of organisations and experts to explore
electricity supply in inner Sydney and consider some possible initiatives as part of developing a
solution.
Almost 100 representatives and experts gathered to hear speakers from TransGrid and Ausgrid asp p g p g
well as experts from CSIRO and City of Sydney.
There were representatives from consumer advocacy groups, academics, governmentThere were representatives from consumer advocacy groups, academics, government
representatives, regulators, large energy users, infrastructure organisations and energy providers.
Among the delegates there was a concerted call for an overhaul of regulatory framework to provideAmong the delegates there was a concerted call for an overhaul of regulatory framework to provide
incentives to electricity networks, for non-network alternatives.
Planning Inner Sydney’s Electricity Future Forum 2
Thursday, 19 June 2014

3. Reliability Standards
Planning Inner Sydney’s Electricity Future Forum 3
Thursday, 19 June 2014

4. POWERING SYDNEY’S FUTUREPOWERING SYDNEY S FUTURE
Reliability Standards
Tim George
DIgSILENT Pacific
June 2014
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5. Reliability standards
Overview:
• What is a reliability standard?What is a reliability standard?
• Application and practical considerations
• TransGrid’s reliability standard
• Comparing with international practice
• Considerations when advocating a change

6. Auckland blackout - 2006
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7. Reliability – when you do not have it….
Report confirms Auckland blackout preventable
Wednesday, 12 July 2006, 8:17 amy, y ,
Press Release: New Zealand National Party
Hon Nick Smith
National Party Energy Spokesman
11 July 2006
Report confirms Auckland blackout preventable
Auckland’s blackout on June 12 would have been prevented if proper inspections had been
carried out correctly, says National Party Energy spokesman Nick Smith.
“The Connell-Wagner report, released today, contradicts an earlier Transpower report which
said there was no proof that the failing shackles were inspected in 2003.
“It is an indictment of Transpower that the paper trail around this critical infrastructure does
not exist Connell-Wagner concluded that either the inspection didn’t occur or that it was notnot exist. Connell Wagner concluded that either the inspection didn t occur or that it was not
done properly, as it would have been obvious that the shackles were in bad shape in 2003.
“The report also confirms that the Otahuhu substation was sub-standard in having key
strategic lines cross each other. This should have been identified and fixed long ago. The fact
that it wasn’t confirms that Transpower has not been sufficiently focussed on ensuring securitythat it wasn t confirms that Transpower has not been sufficiently focussed on ensuring security
of electricity supply.
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http://www.scoop.co.nz/stories/PA0607/S00150/report-confirms-auckland-blackout-preventable.htm

8. What is a reliability standard?
• Policy decision on risk and uncertaintyPolicy decision on risk and uncertainty
• A reliability standard does not:
G t i t ti f l– Guarantee interruption-free supply
– Cause, on its own, over-investment
• A reliability standard does:
– Create a trigger point, when action is required

9. Application
• Most large power systems define a reliability standardMost large power systems define a reliability standard
– Usually deterministic – eg failure of up to two assets
– Can be economic – eg New Zealand
• Common to have multiple standards
– Major cities and critical loads
M i t i i t (‘ id’ ‘b kb ’)– Main transmission system (‘core grid’ or ‘backbone’)
– Radial transmission system
• Reflect a position on the ‘cost-reliability’ curve
– Reducing reliability standard
• Increases number of failures – cost of unreliability increases
• Reduces infrastructure costs – less investment
– Increasing reliability standard
• Reduces unreliability costs
• Increases infrastructure costs• Increases infrastructure costs

10. Trading reliability and cost
Cost of unreliability
Cost
Cost of unreliability
Reliability

11. TransGrid’s Reliability standards
• Main Transmission Network:Main Transmission Network:
– P50 load conditions:
N-1 for reasonably probable generation patterns
One item of reactive plant out of servicep
No load shedding
– P10 load conditions:
As above but for a limited set of generation patterns

12. Urban and suburban areas
• Joint reliability standard with DNSP (two part)• Joint reliability standard with DNSP (two part)
1. Simultaneous outage of:
One 132 kV cable; and
One 330 kV cable or 330/132 kV transformer
2. Outage of a 132 kV busbar
• Not quite as onerous as N-2, but still strict
Higher standard because of higher consequences– Higher standard because of higher consequences

13. What does the reliability standard mean?
Busbars:
One 132 kV cable (red dashed line)
Fault on Bus B
affects six circuits
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One 132 kV cable (red dashed line)
One 330 kV cable (green solid line)

14. International Practice
• NERC (North America)• NERC (North America)
– Standard is 1200 pages long, very wide ranging
– Relevant sections indicate N-2 for critical loadse e a t sect o s d cate o c t ca oads
• New Zealand
– N-1 for Core Grid but can enhance if economic
– Generally yields better than N-1 for critical loads
– Some specific loads have contracted for N-2
• Europe
Mostl N 2 for cities / critical loads– Mostly N-2 for cities / critical loads
– N-1

15. Summarising
• Reliability standard is a triggerReliability standard is a trigger
– Indicates action is required
– Does not dictate what needs to be done
Economic merit of options to be assessed– Economic merit of options to be assessed
• Reliability is a trade-off between infrastructure cost and cost of
interruptionsinterruptions
– Reducing the reliability standard
• Decreases infrastructure costs
• Increases unreliability costs• Increases unreliability costs
• Sydney reliability standard
Similar to international practice– Similar to international practice
– Has pragmatic elements to avoid over-investment
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