1. AUFLS Load Control for HVDC Pole 3
Commissioning
Challenges and Findings
Load Control for HVDC Pole 3
Commissioning
VDC Pole 3 Commissioning
By Lekshmi Mohan
Justin Blass

2. PURPOSE
The AUFLS Pole 3 Ready project was initiated
 To improve the performance of the current
AUFLS scheme prior to the commissioning of
Pole 3.
 To increase consumer confidence in the security
provided by the AUFLS system during
commissioning.

3. 50 -
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55 -FREQUENCY(Hz)
INTERRUPTIBLE LOAD
AUFLS RANGE
BLACK START
OVER FREQUENCY RANGE
GENERATORS
OPERATE SAFELY

4. DEMAND GENERATION
16%
16%
AUFLS BLOCKS
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FREQUENCY(Hz)
BACKGROUND

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FREQUENCY(Hz)
DEMAND GENERATION

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FREQUENCY(Hz)

7. 50 -
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FREQUENCY(Hz)

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FREQUENCY(Hz)
CCGT PLANT

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OVER FREQUENCY RANGE
AUFLS RANGE
BLACK START

11. • Compliance and provision behaviour
• Variations in AUFLS percentage
• Large amount of AUFLS armed during peak and
weekends
PROBLEMS IDENTIFIED

12. Commissioning risk
Discrimination between blocks
Problem
Number and size of AUFLS
blocks
Quantity of AUFLS load armed
PROBLEM ANALYSIS

13. Limitations
CONTROLTIME
LIMITING FACTORS
ACCURACYVISIBILITY

14. DESIGN QUESTIONS
• How big of AUFLS blocks can system handle?
• What size AUFLS blocks do we expect?
• How much AUFLS load could we control?
• How will we coordinate and control the reduction
process?

15. METHODOLOGY
• Bipole tripping event
• Worst case load profiles for month.
• 3 different stages of study
– Existing scheme (2 x 16%)
– Increment in block size (+1%) until 52 Hz is
reached
– Over frequency arming (OFA)

16. RESULTS

18. AUFLS REDUCTION PRINCIPLES
• Reduce AUFLS load when possible
• Limit disarming to once a day
• Observe a safety margin with RMT (17%)
• Spread reduction geographically when possible

19. INDUSTRY PARTICIPATION
• Urgent Code Amendment enabled obligation
modification
• Network companies volunteered to participate
• Various GXP and Vector relays were organised into
controllable groups
• Special thanks to Vector, Counties Power, Powerco,
Unison, Scanpower, Waipa, and WEL Networks for
participating

21. CONTROL PROCESS
TRANSPOWER
OPERATOR
VECTOR
OPERATOR
OVER
FREQUENCY
RESERVE
PROVIDER
VECTOR
RELAYGXP
RELAY

22. CONCLUSION
• Corrective action was needed during the commissioning of Pole 3.
• The control process improved reliability during commissioning.
• The control process will be carried out for the commissioning of the
new Pole 2 controls.
• The SO is continuing a long term initiative to improve the scheme
design and compliance requirements. To be proposed in 2013.

23. THE AUFLS JOURNEY