SAIDI and SAIFI indices guiding towards more reliable distribution network

People consume more electricity than ever before and expect to get it without interruptions. Authorities are increasingly interested in how well electricity is provided to people. This puts pressure for electrical utilities to provide evidence of the reliability of their electricity distribution. Today, it is fairly common that companies measure the length and number of interruptions in electricity distribution. For this they use international standards called SAIDI and SAIFI created by Institute of Electrical Electronics Engineers (IEEE).


SAIDI (System Average Interruption Duration Index) – a system index of average duration of interruption in the power supply indicated in minutes per customer.


SAIDI = total duration of interruptions for a group of customers

                              Number of all customers


SAIFI (System Average Interruption Frequency Index) – a system index of average frequency of interruptions in power supply


SAIFI =    total number of interruptions for a group of customers

                              Number of all customers


Indices serve as valuable tools for comparing electrical utilities performance reliability. Nordic authorities have adapted SAIDI/ SAIFI criteria to monitor electricity distribution in their markets. Some countries, including Finland have taken in use regulations that demand distribution network operators to pay reimbursement for customers for long interruptions in electricity distribution. In addition, the aging network infrastructure and increasing use of renewable energy sources force utility companies to increase network's visibility.

Ensto has several ways to improve SAIDI and SAIFI. Our Power Quality solution improves SAIDI and SAIFI indices with minimal investment costs. Solution is especially suitable for sparsely populated areas, it can provide a temporary solution to guarantee uninterrupted good quality electricity distribution in an aging distribution network or a permanent solution. Network Automation plays a key role in fast fault recovery and improves reconfiguration of the grid.