Resilience of Distribution Grids



Due to climate change the number and strength of events and hazards against critical infrastructures increased during the previous years. Storms, flood, earth quakes lead to large damage of critical infrastructures and life-sustaining goods cannot be provided. On the other hand the increase of large cities especially in Asia will also lead to high impacts if infrastructure like electricity is not available.
Normally all electrical grids are planned, operated and controlled to provide an economical, safe and reliable supply. In this context the reliability considers only the most likely events. Hazards, storms and other rare events are mostly not considered in concepts and have also to be incorporated in automation and control strategies. For these “High Impact Low Probability” (HILP) events a complete strategy has to be developed including the crisis strategies of utilities as a part of local and regional crisis management. So it is not only grid planning topic but also includes grid operation. In this context, active distribution systems have the potential to improve the distribution system reliability and resiliency. Indeed, online network reconfiguration, DER operation, and innovative schemes as microgrids are valuable design options to increase the redundancy of the system, leading to higher capability to serve critical loads and services. 
The reliability of distribution systems is measured essentially by the frequency and duration of power outages (e.g. SAIFI and SAIDI). Since most outage scenarios involve simple events, modern Fault Locators Insulation and Service Restoration systems (FLISR) are capable to reduce the extension and the duration of service interruptions. Differently, the resiliency of a distribution system is defined with respect to a system’s ability to withstand rare and extreme events (snow storms, hurricanes, earthquakes, terroristic attacks). Numerous components may be damaged, transmission/distribution system facilities may not be ready for service restoration, and the communication and remote-control capabilities may be lost. Furthermore it has to be ensured that other infrastructures like water supply, police and medical centers, traffic, … will be supplied as soon as possible. Additionally control strategies of cities during these events have to be considered. Therefore the electrical grid cannot be investigated without its interactions to other infrastructures. As a result, by existing reliability metrics, a highly reliable distribution system is not necessarily resilient. Therefore, new tools are needed to assess the ability of the ADS to withstand outages after the extreme event.
The working group will investigate impacts of events to the electrical supply (from generation, distribution to the end customers). 

Main topics

1. Impact of different events to the electrical supply system
2. Interdependence of the electrical infrastructure and others (e.g. water, …)
3. Evaluation of needs and the existing resilience
4. Strategies for planning, control and operation
5. Overall  strategies for cities in case of an HILP event including crisis strategies of utilities
6. Role of innovative networks (e.g. microgrids), energy storage devices and dispersed generation against resiliency. 

Convener :
Maria Luisa Pestana, Electricidade de Portugal Distribuição, Portugal

Members :            

Brouns Guido, Enexis, Netherlands
Capuder Tomislav, University of Zagreb, Croatia
Carlini Claudio, RSE, Italy
Cremers Roger, KEMA Nederland BV, Netherlands
De Masi Mauro, E-Distribuzione, Italy
Kjølle Gerd, SINTEF Energy Research, Norway
Lampard Terrence, NSW Treasury, Australia
Oddbjornn Gjerde, SINTEF Energy Research, Norway
Sanchez-Torres José, EDF, France
Šiljkut Vladimir M., JP Elektroprivreda Srbije, Serbia
Stancu Elena, Electrica SA, Romania
Suo Zhixin, China Southern Power Grid, China
Tapper Matz, Energiföretagen Sverige, Sweden
Tordjman Philippe, General Electric, France
Williams Pierre, Sicame Group, France