Economic outage scheduling of transmission line for long-term horizon under demand scenarios

Abstract

Outage scheduling for maintenance in asset management of electrical transmission and distribution system plays an important role in power system reliability. For instance, failure probability of transmission line may change from time to time due to exogenous conditions. Impact of failure or service interruption can be described by using uncertainty condition (e.g., demand scenarios) while designing the long-term model for outage scheduling. Within a year horizon, a transmission system operator needs to schedule the maintenance outage of set of transmission lines due for maintenance. This is important because transmission line maintenance schedule ought to minimize the total maintenance cost and transmission provider’s loss of revenue while satisfying the reliability and the network requirement. It is expected that in coming years, there will be substantial increase in renewable energy in-feed to the primary grid. Definitely, transmission system operators (TSOs) have to tackle such increase in demand and generation while addressing security of supply (SoS); thereby transmission assets will play an important role since TSOs are not in favour of new investments. In order to maintain such reliable system with SoS, TSOs ought to have a proper and flexible maintenance scheme for their transmission assets. The scheduling scheme should be able to determine the exact transmission asset in the cluster of network which can be brought out of service for maintenance. In this thesis we are particularly considering transmission lines as the transmission asset for outage schedule. The scheduling scheme should be accurate and fulfil the required constraints, both maintenance and network, while keeping the system reliable throughout the maintenance horizon. To solve such maintenance scheduling problem, benders decomposition technique is adapted in this research work incorporating different demand scenarios. With the help of demand scenarios, different outage scenarios are evaluated and the corresponding schedule is obtained using stochastic programming. Stochastic programming provides an adequate modelling framework for this two-stage optimization problem. Optimization under different demand scenarios, spanning two-stage stochastic programming approach is used in this research study. For validation, medium (modified IEEE RTS-24 bus) and large (modified IEEE-118 bus) systems are studied, all in the GAMS environment.