Distribution Series Capacitor Application for Improved Motor Start and Flicker Mitigation

Voltage flicker can become a significant problem for power distributors when large motor loads are connected in remote locations. Installation of a series capacitor in the feeder strengthens the network and allows these loads to be connected to existing lines, avoiding more significant investment in new substations or new distribution lines. This paper describes a real-life application of a distribution series capacitor in Alberta, Canada where a long feeder is compensated to reduce flicker caused by infrequent start of large motors. To ensure performance within established feeder operating parameters, network simulation tools are used in design and engineering of the series capacitor. Overvoltage protection system and methods to detect and overcome problems related to subsynchronous resonance during start of large motors is also described. This paper concludes that using distribution series capacitors is an effective and inexpensive method for network operators to connect large motor loads at the extremities of long distribution lines