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The safety of workers and the public has been one of the most important concerns for electric utilities in the past and will continue to be so in the restructured electricity market. In this connection, Hydro One has assessed a number of methodologies for quantifying safety risks associated with the catastrophic failures of transmission station or substation equipment. This paper describes the assessment and its findings including the following: the study assessment methodology, data required, results obtained for some selected station equipment and study recommendations. Index Terms--Acceptance risk criteria, catastrophic events, failure rates, personnel exposure, risk assessment, risk of safety incidents, station equipment, transmission station.

Customer delivery systems have been planned to deterministic criteria for a long time. With these criteria, new capacity is determined when the system load is just equal to the system limited time rating. Even, some electrical utilities in North America allow for some positive reserve margin in order to cover for load forecast uncertainty. These deterministic tic criteria do not quantify the reliability of the system and in many situations, can result in over-designed systems and therefore, the electricity users can end up paying higher prices for electricity. In a competitive electricity market, transmission system owners or providers should try to keep the cost of upgrading, operating and maintaining their systems as low as possible while meeting the expectations of their customers and regulatory rules. This paper describes the application of a value-based approach to the planning of customer delivery systems. In this application, the reliability of the system is expressed as a function of the reserve margin (the difference between the station limited time rating and the station forecast load) and the optimal reserve level is obtained when the total system cost, the sum of capital and unreliability costs, is minimal. Sensitivity studies are carried out to determine the impact of changes in some key parameters on the optimal reserve margin. Examples are presented to illustrate the concepts involved. Index Terms--Capital cost, customer delivery system planning, customer interruption cost, limited time rating, load forecast uncertainty, reserve margin, value-based reliability assessment.

The number of performance-based contracts between customers (end-users of electricity) and transmission system providers is expected to grow when the electricity market opens up to competition and for customer choice. In these contracts, specified levels of supply reliability with regard to service continuity and power quality will be specified and rewards for honoring these performance levels may be awarded and penalties may be imposed for failing to honor them. These rewards and penalties will be clearly spelled out in the contracts. Transmission system providers may have to assess in advance the level of supply reliability to customers before entering into any of these agreements in order to minimize the financial risk associated with these contracts. This paper describes a probabilistic method for evaluating the level of supply reliability to a customer entering into a performance-based contract with a transmission provider. The evaluation process includes performance measures that reflect both reliability and quality of power supply to the customer. The proposed method can be used not only to assess various utility solutions for improving the reliability and power quality to the customer but also to link the level of supply reliability to the cost of service. An example is given to illustrate the concepts involved. Index Terms--Customer, delivery system, feeder, performance-based contract, power quality, reliability.