A Probabilistic Security Criterion for Determination of Power Transfer Limits in a Deregulated Environment

SUMMARY This paper presents a novel approach to on-line security control and operation of power transmission systems. The approach is based on a probabilistic criterion aiming at on-line minimisation of the total grid operating costs, defined as the sum of expected interruption costs and congestion costs in a specified period of operation. The probabilistic criterion is described and illustrated by a case study example. The approach currently applied by the Norwegian transmission system operator, enables flexible power transfer limits by taking into account various criteria, such as cost of redispatching, weather conditions and system protection. This is a practical approach in order to meet the increasing demand for flexible and efficient utilisation of the transmission grid in a changing environment, and can be seen as a first step towards implementing probabilistic security standards.