Lessons learned from the power outages on 29 July and 21 September 1999 in Taiwan

Two of the most severe power outage events took place in Taiwan in the year 1999. One occurred at 11:31 p.m. on 29 July when the #326 transmission tower collapsed due to a landslide, which disconnected around 83% (8.46 million) of the electricity consumers from the energy supply. About two months later, a devastating earthquake struck at 1:47 a.m. on 21 September. The quake halted the power supply to over 6.8 million users. Officials estimated the minimum total cost of the damage from both events to be several billion New Taiwan Dollars (NTD) (i.e. USD $1≈NTD $35), including manufacture losses and facility damages from high-tech industrial parks, asset damages and purchasing new equipment from the utility, and business losses from other industry sectors. The paper provides a technical review of both power failures and lessons learned from the outages. The paper summarises the system characteristics and the network conditions prior to, during and after both incidents. Finally, the lessons learned from both power failures and future strategies to be adopted by Taiwan Power Company (TPC) are concluded.