Adding discharge capacity and redundancy using existing turbines

The ability to discharge water safely plays a vital role in overall dam safety. There are several arrangements to provide discharge capacity, the main ones being surface and low-level spillways. This paper presents an alternative concept whereby the regular waterway through the turbine is used. In the event of grid loss, a local load is connected which enables the unit being used to operate in isolation from the main grid. This dump-load concept has been tested at pilot scale in Sweden, with positive results, and therefore has been proposed to be applied in existing powerplants. Additional discharge capacity via a dump-load has a number of benefits compared with conventional spillgates, the most obvious being its significantly lower investment cost, fast installation and provision of redundancy.