Protection against penstock pressure pulsations at Nam Theun 2

Penstocks can be subject to hydro-acoustic resonance, resulting in pressure pulsations. Examples are rare but consequences can be as dramatic as a penstock breakage. A few tens of such events have been reported worldwide. This paper focuses on the potential of this phenomenon occurring in the Nam Theun 2 (NT2) scheme and describes simulations when pressure pulsations in the penstock would exceed the design pressure. The use of a passive quelling device to mitigate the risk from this source is reported. The paper describes the commissioning tests and results of the new device since it was fitted last year.