Protection issues related to pumped storage hydro (PSH) units: Members of the “Working group on protective relaying for pumped storage hydro units”;

Pumped storage hydroelectric (PSH) units provide protection complexity not encountered in conventional generating plants. As PSH units operate in both generating and pumping modes, attention must be given to the frequency and phase rotation presented to the relaying. In some PSH applications, additional relays and switching of VT and CT connections are applied to cope with these challenges. This paper serves as an update to the original 1975 paper based on survey results when the majority of relays were of the discrete variety. Discrete relays did not have frequency tracking characteristics or provide operation mode based phase rotation selection, however newer technology can adapt to these PSH operational challenges. With the advent of new relaying technology, including static and microprocessor designs, an updated PSH Protection Practices survey was conducted in 2012 to quantify recent relaying practice and protection application trends on PSH units.