Transmission Planning in a Modern Market Environment Siemens Power Technologies International Transmission Planning in a Modern Market Environment

Objectives of Talk Discuss electric power transmission reliability issues, assessment methods and tools Present opportunities for applying probabilistic techniques

Characteristics of Today’s Transmission System Analysis Reliable on a system-basis May vary by location Prevalence of remedial measures Designed to survive severe, probable events Deterministic criteria, typically Without explicitly predicting likelihood of occurrence

Reliability Assessment Approaches Contingency enumeration Limit scenarios and contingencies Monte Carlo simulation Use random sampling

Reliability Criteria Based on previous history of failure phenomena Mainly deterministic, but reflect relative likelihood of component failures Defined in terms of: Scenarios Analyses Acceptable/unacceptable conditions

Deterministic vs. Probabilistic Tests system performance under different conditions (N, N-1, N-2, etc.) Determines contingency outcome Makes “Pass/Fail” decision Probabilistic Reflects risk of equipment failures Multiple component failures may have more severe consequences, but are less likely to occur (have lower probabilities)

Equipment Outage Statistics Probabilistic calculations require input of equipment outage statistics Data from historical records of equipment failures Grouped by equipment type, voltage level, rating kV Transient Outages Temporary & Permanent Outages Line Related Terminal Related F (/mi-yr) R (hours) F (/yr) 230 0.010 7 0.100 10

Probabilistic Indices System problem (performance criteria violation) indices Frequency Average duration Probability

Loss of Load Indices Energy not served (MWHr/yr) Bulk power interruption index (1/yr) Bulk power energy curtailment index (Hr/yr) Customer indices: SAIDI & SAIFI

Unserved Energy Varies with load and dispatch Studying only peak load may overestimate unreliability Model a series of load/dispatch conditions 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2000 4000 6000 8000 Hours Per Unit Load Load Served 0.5 0.6 0.7 0.8 0.9 1.0 1.1 2000 4000 8000 Hours Per unit load 6000

Value-Based Reliability Cost of unreliability Cost of reinforcements/must-run contracts Value-based pricing System Reliability Cost Total Cost Customer Impact Reinforcements

Deterministic vs. Probabilistic Example Line is overloaded during the outage of a parallel circuit Load Center Generation Probabilistic Line is overloaded once a year with an average duration of 5 hours

System vs. Customer Focus Example System Perspective Line is overloaded by 20% during a circuit outage Load Center Generation Customer Perspective 200 MW of load is interrupted during a circuit outage

Generation vs. Transmission Example Scenario A Scenario B Urban Area Urban Area In-City Generators Add Tie Lines Retirement of in-city generation, increased dependence on imports Random outage behaviors of generators and transmission components are different Need to consider probabilistic aspect

Comparing Options Example New generation Equipment upgrades Transmission additions Maintenance changes Pricing change 1000 2000 3000 4000 6000 Cost of Investment Cost of Unreliability

Maximizing Transfer Capability Example Transfer limits typically computed according to deterministic basis (N-1) Adopt probability approach to compare risk and reward 2 4 6 8 10 12 300 400 500 600 Transfer Limit Cumulative frequency per year

Transmission Line Ratings Example Ratings tend to be static Often based on worst case assumptions Solution: develop probabilistic function 10 20 30 40 50 60 70 80 90 100 500 1000 1500 2000 2500 3000 Line Rating (amps) Static rating Monitored ratings % of time

Roles of Reliability Location-specific indicators Parts of power system that are susceptible to failures Risk-based assessment Vulnerability to system failures Customer focused measures Service quality and reliability Reliability as a product Pricing accordingly to level of reliability

Thank you for your attention! Bob Zeles Principal Consultant Siemens Industry, Inc. Siemens Power Technologies International 7810 Shaffer Parkway Suite 100 Littleton, CO 80127 Phone: +1 (303) 568-7133 Mobile: +1 (303) 803-4930 E-mail: robert.zeles@siemens.com