Framework for comparing power system reliability criteria

Evelyn HeylenProf. Geert DeconinckProf. Dirk Van Hertem

Durham Risk and Reliability modelling for Energy Systems dayNovember 12th, 2014

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IntroductionCurrent situation in power system reliability management• Deterministic N-1 criterion with various shortcomings• Major evolutions in the power system • Increasing uncertainties

Probabilistic reliability management• Take into account probabilities• Could tackle shortcomings of N-1• Many academic references• Not fully used in practice

Amongst others due to lack of quantified benefits

Framework for Comparing power system reliability criteria

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Outline

• Framework for comparing power system reliability criteriao Overviewo General schematic of the implementationo Implementation of deterministic reliability management moduleo Assumptionso Comparison of deterministic criteria

• Conclusion

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Outline

• Framework for comparing power system reliability criteriao Overviewo General schematic of the implementationo Implementation of deterministic reliability management moduleo Assumptionso Comparison of deterministic criteria

• Conclusion

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Framework for comparing reliability criteria

Objectives of the framework:1. Quantification of performance of various power system reliability

criteria and their management2. Comparison of performance3. Identifying alternative reliability criteria

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General schematic

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1. N-1 criterion: ‘System should be able to withstand at all times the loss of any one of its main elements (lines, transformers, generators, etc.) without significant degradation of service quality.’ 2. State enumeration: • Run power flow• Check for operational

limit violations

4. Reliability actions• Corrective actions• Preventive actions

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Deterministic reliability management module

3. Decision = balance reliability and cost

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Reliability management modules

Reliability assessment

methods

Analytical contingency enumeration

Event tree/fault tree analysis

Random sampling (Monte Carlo)

Markov analysis

Reliability criteria

N-k

Optimization

Limits on reliability indicators

Optimization and limits on reliability indicators

Reliability control

Preventive/corrective control

Asset management

System development

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Reliability management modules

Reliability assessment

methods

Analytical contingency enumeration

Event tree/fault tree analysis

Random sampling (Monte Carlo)

Markov analysis

Reliability criteria

N-k (i.e. N-0 and N-1)

Optimization

Limits on reliability indicators

Optimization and limits on reliability indicators

Reliability control

Preventive/corrective control

Asset management

System development

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General schematic

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Framework for comparing reliability criteria

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Data generation• Unit commitment model• Monte Carlo

Data modules• Matlab m-file

Events and triggers• Input reliability assessment

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Test Setup (I)• Reliability criterion e.g. N-1, N-0 Extended problem formulation using

islanded systems

• Reliability control e.g. preventive, corrective Interlinking constraints between

islanded systems

PF = Power flowSW = Social welfareOPF = Optimal power flow

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Test setup (II)• Objective function Minimal cost for society == maximal social welfare

• Probabilistic approach in large system

State selection

PF = Power flowSW = Social welfareOPF = Optimal power flow

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PF = Power flowSW = Social welfareOPF = Optimal power flow

Simulation• Optimization, e.g. SCOPF, OPF Economic dispatch of generators satisfying operational limits, reliability criterion and control constraints

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TSO actions• Short term: Preventive and

corrective actions• Medium term: asset

management & operational planning

• Long term: system development

PF = Power flowSW = Social welfareOPF = Optimal power flow

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Reliability assessment• Check performance of reliability

criterion and reliability control using PF and OPF for: • All contingency cases• Contingency cases of truncated

state space• Specific scenarios (i.e. events)

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Events

• Evaluate performance of reliability management for specific cases

• Time series including results of events due to:o Natural hazardo Operational conditionso Human behaviour

• Which can lead to:o Discrepancy between generation and loado Generator/branch outage at particular moment in timeo Failure caused by several simultaneous faults (failure of cable or

power line in same trace etc.)o …

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Economic evaluation• Based on market model

• Social welfare evaluation• Total cost evaluation

Could be substituted by more complex evaluation techniques

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Comparison of reliability criteria• Methodology for comparing reliability criteria• Appropriate metric for comparing reliability

criteria

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Assumptions• No generator ramp rates or minimal on/off times

• Knowledge of Value of Lost Load at every node

• Linear cost curves constant marginal costs of different units

• Corrective actionso Generation redispatch o Load shedding

• Constant failure and repair rates exponential distribution

• Aggregated branch models

• No failure of corrective actions

• Reliability assessment considers only branch outages

• No forecasts errors included (wind, load…) No stochastic, multi-stage optimization

• Single TSO, Single area

• DC power flow

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Comparison: Results

• Three node test system

• Comparison ofo N-0 correctiveo N-1 preventiveo N-1 corrective

• Varying value of lost load (VoLL)

Performance of reliability criteria and their management

dependent on VoLL

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Outline

• Framework for comparing power system reliability criteriao Overviewo General schematic of the implementationo Implementation of deterministic reliability management moduleo Assumptionso Comparison of deterministic criteria

• Conclusion

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Conclusion

• Comparing power system reliability criteria is important

• Framework for comparing power system reliability criteria and reliability management o Objectives of the framework:

1. Quantification of performance of various reliability criteria and their management

2. Comparison of the performance

3. Identifying alternative reliability criteriao Quite complex, even with many assumptions included

• Preliminary result: Performance of reliability criteria and their management dependent on VoLL

Thank you!Questions?

Evelyn.Heylen@esat.kuleuven.beGeert.Deconinck@esat.kuleuven.beDirk.Vanhertem@esat.kuleuven.be

The work of Evelyn Heylen is funded by:

Research in the framework of the Garpur project