Capacity-use and reliability based transmission embedded cost allocation with temporal considerations

Abstract

Transmission services have to be provided as a separate item in a de-regulated or vertically restructured electricity supply industry. Though the primary function of a transmission line is to transmit power from source point(s) to loading point(s), major lines also play an important role in security. Sometimes a particular transaction cannot take place if a particular line is unavailable and, moreover, a specific line may be more important for the security of a particular transaction than it is for others. Clearly reliability is a relevant consideration in equitable cost allocation. A method for transmission line embedded cost allocation among transmission transactions accounting for both line capacity-use and reliability benefit is presented. Line capacity-use is determined by the amount of power transmitted, while the reliability benefit is calculated as the increment of the total probability of system failure, with the line out of service, compared to when the line is in service. Capacity-use is determined using a full AC power flow and hence the effects of reactive power can also be investigated. The cost allocation to each transaction according to the capacity-use and reliability benefit patterns throughout an accounting period during which system loading and line failure probability are varying are studied.