Investigating the impact of asset condition on distribution network reconfiguration and its capacity value

Abstract

Generally, decisions regarding Distribution Network (DN) operations are based only on operational parameters, such as voltages, currents and power flows. Asset condition is a key parameter that is usually not considered by Network Management Systems (NMSs) in their optimization process. The work in this thesis seeks to quantify the extent to which asset condition information can positively influence network operation and planning; specifically through Distribution Network Reconfiguration (DNR). Asset condition can be translated into Health Indices (HIs) and failure rates, allowing an NMS – or an optimization algorithm – to make better informed decisions. This is realized via appropriate asset condition assessment and failure rate models. The effect on optimal DNR is evaluated – focusing on substation condition and reliability; the idea of load transfer from one feeder or substation to a more reliable one is key in the proposed methodology. Condition-based risk is considered in the DNR problem, and the impact of transformer ageing on network reconfiguration is examined as well. The effect of asset condition assessment and ageing – which depends on the type of network branches (overhead lines or underground cables) – on the optimal distribution switch automation is also investigated. Finally, a probabilistic method is developed to quantify the contribution of DNR to network security considering asset condition and ageing. The results show that savings can be in the order of tens of thousands of U.S. dollars for a single DN; this corresponds approximately to 10% of the annual cost of active power losses. This can mean hundreds of thousands – or even millions – of U.S. dollars of savings for a single DN operator. Regarding the optimal placement of automated switches, neglecting the effect of asset ageing can result in an underestimation of expected outage cost by as much as $223,000 over a 20-year period. Finally, ignoring the contribution of DNR to security of supply can double the estimation of network risk; in addition to that, disregarding asset condition and ageing results in a reinforcement deferral overestimation of two years.