Maguga Hydro Power Project – Swaziland

Background

The Maguga dam on the Komati River, Swaziland releases in the order of 25 m³/ sec to generate 19 Mw of hydropower as peaking power over 2 three hour periods on average per day.  These high peak flows have to be regulated to a constant lesser flow over the full day downstream into the Komati River.  It was therefore necessary to regulate this flow behind a 17 m high regulating weir.  The regulating device had to be fully automatic to regulate a constant flow with a varying upstream water level.

Description

The consultants after evaluating various types of regulating devices, selected the FDS diaphragm valves (DV) as they are fully automatic, self regulating valves which are locally manufactured and supported.  The DVs also do not require any electro mechanical means to operate the valves and also have minimal maintenance.

Two 1600 NB DVs were installed into discharge chambers which, because of the radial discharge of the DVs, effectively dissipated the discharge energy, thereby creating a shorter and more effective discharge channel leading to a measuring crump weir.

The discharge is controlled by a float valve which maintains a fixed water level over the crump weir.  The flow rate is changed when required by adjusting the float valve.  The DVs have proved to be accurate in maintaining a set discharge, with a varying upstream head.