Shigeo Sagai's research while affiliated with Central Research Institute of Electric Power Industry and other places

The effect of an outage caused by a disaster is serious to the society, because the power distribution line is a common basic infrastructure for life support. And the time estimation of emergency restoration process of power distribution line after a disaster is an emerging problem for the safety and security of the society. But the time estimation is a difficult problem and the only practical method in use is a simple approximation method, which doesn't take account of geographical characteristics of the objective area. So, we developed a method which can take account of the influences caused by the geographical characteristics of the objective area on the estimation of the emergency restoration. In this article, we describe an experimental analysis by the method.

We have developed a multi-agent simulator, the objective of which is to analyze emergency restoration processes damaged by regional disasters such as earthquakes or typhoons. The restoration simulator facilitates our comparison of multiple emergency restoration procedures to cope with various circumstances of disaster-related damage. In this article, we evaluate the effects of changes of mobile speeds of each worker caused by the road blockades and/or traffic jams during disaster relative to the total emergency restoration time. The main findings are 1) we confirmed that the sensitivity analysis of the total completion time relative to the change of the mobile speed become executable via the use of the restoration simulator, 2) the delay of the emergency restriction could be mitigated by proper restrictions of the road.

We are developing a tool which can simulate the emergency restoration process of electric power distribution facilities in order to examine the methods to speed-up the process. This report is aiming following two objectives; 1)describing an overview of the tool “restoration simulator” that simulates the emergency restoration process of the distribution facilities after a disaster, 2)evaluating effectiveness of various restoration methods to speed-up the restoration process using the tool.

This paper introduces the methodological challenge of identifying and quantifying the interdependencies among several critical infrastructures. First, interdependency structures during a natural disaster are modelled-based on past events, considering supply (electricity, water and gas), communication (internet and telephone) and transportation infrastructures (road networks). Interdependencies are defined with respect to physical, functional and socioeconomic interrelationships. A quantification strategy is then introduced based on empirical surveys and economic models. As a case study, the developed model is applied to the 2004 Mid-Niigata Earthquake, which severely damaged infrastructure systems in the central mountainous area of Japan.

We propose a multi-agent simulator of an electric power distribution equipment damage restoration process due to a disaster. In the proposed simulator, the agents, who imitate the restorer, are modeled by extracting main work steps of the actual restoration process. The major functions of the proposed simulator are 1) to imitate the restoration process, 2) to estimate the alternative strategy, and 3) to improve the restoration time estimation by adding the damage information reported by the inspector. In this paper, we show an outline of the prototype and demonstrate numerical examples to confirm the effectiveness.