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Implementation and evaluation of commonly used risk analysis methods applied to a regional power distribution system. Carl Johan WALLNERSTRÖM and Patrik HILBER, KTH – Royal Institute of Technology – Sweden Julio GADEA TRAVI, Gotlands Energi / Vattenfall – Sweden. Background.
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Implementation and evaluation of commonly used risk analysis methods applied to a regional power distribution system Carl Johan WALLNERSTRÖM and Patrik HILBER, KTH – Royal Institute of Technology – Sweden Julio GADEA TRAVI, GotlandsEnergi/Vattenfall – Sweden
Background • Mandatory risk and vulnerability analysis • Regarding reliability, including an action plan • Annually reported by DSOs, first time in 2011 • Additional incentives: • Quality regulation (0.05-12 hour outages) • Laws regarding >12/>24 hours outages Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Studied system • Gotland is the largest island in Baltic Sea • A lot of wind power, HVDC link to mainland • Owned by Gotland Energy / Vattenfall AB • Concerns regarding that existing risk management not suit all specific conditions Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
The aims of this paper • Describe and evaluate the first year and find suitable methods for the future • The results can hopefully be useful, both by companies that will perform risk analyses and by method developers • University and DSO knowledge exchange Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Paper contents • Description of current situation in Sweden • Summary of commonly used risk analysis methods used by DSOs • Description and evaluation of former risk management performed by this DSO • Proposal of future methods to use Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Risk management performed • Power lines: a risk method develop by Swedish Electrical Utilities’ R & D Company (Elforsk AB) • Risk value (0.05-400) based on three parameters: Exposure (probability), Load (consequence) and Endurance (reliability) Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Risk management performed • Substations: risk matrix (1-16) method based on authority recommendations • Risk value (RV) 1-4 (green): acceptable • RV 6-8 (orange): consider risk reduction • RV 9-16( red): risk reduction must be implemented in a near future Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Risk management evaluation • 10 kV: used method seems proper • Two parts of performed risk analyses were identified to have concerns • 70/30 kV lines: Score tables were not adjusted to few but large load points • Substations: A lot of attention to details Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Proposed modified 30/70 kV • Evaluation: Proposed method are more suited for 70/30 kV lines Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Proposed modified substations • Risk matrix, similar as for power lines • Reduction in the number of details • Only orange/red risk are reported: • Orange input to a “maintenance matrix” • Red always mandatory to the action plan • Accurate enough, can save a lot of work. Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567
Concluding remarks • Risk analyses by a DSO were evalu-ated, which indicated two concerns • Existing methods were adjusted and these modified methods were then evaluated with satisfactory results • The results can hopefully be useful both by DSOs method developers Wallnerström C. J., Hilber, GadeaTravi J. – Sweden– Session 5 – PaperID 0567