Systemic modelling and integrated assessment of asset management strategies and staff constraints on distribution network reliability

Aging assets, tighter and tighter budget constraints, and Smart Grid technologies will have profound implications on the reliability of electricity distribution networks. The aim of this paper is to study the impact of changing network characteristics on its reliability in a system-of-systems (“systemic”) way. A key reason for attempting this is to capture the compounding effects of interdependencies due to degrading asset reliability (for instance due to aging), different asset management strategies (including condition monitoring and automation options), and staff resource constraints when performing maintenance and repairs. A Monte Carlo based simulation tool that uses OpenDSS as a load flow engine has been specifically developed to address these issues. The model is demonstrated on an 11 kV test distribution network. The studies clearly demonstrate the need to represent the finite number of staff available for maintenance and repair activities. This limitation allows better capturing unexpected dynamics such as frequent failures reducing maintenance activities, or multiple simultaneous faults having a higher impact than randomly distributed repair times would suggest. Overall, the results thus show how a sequence of planning decisions can compound to degrade network performance much more than might be anticipated. This clearly demonstrates the case for advanced integrated network-staff modelling that needs to be carried out, as proposed in the paper.