Background
Underground works at large hydropower projects often open several faces at once: the powerhouse cavern being excavated, headrace tunnels advancing, some faces drilling and others spraying. With many air points starting at different times, the supply must cover peaks without waste at low demand.
Challenge
The underground powerhouse and headrace tunnels were built at the same time, with several faces drawing air on different schedules. Total demand swung widely and no single unit could cover the peak.
Solution
132 kW and 185 kW electric units run in parallel with common receivers and pressure control. The DM185-26/21 runs continuously for base load and the DM138-23/19 starts and stops as faces open and close, so no unit runs at low load for long — and there is no diesel exhaust underground.
Results
The 185 kW unit carries base load and the 132 kW unit joins only at peaks, so units no longer idle together at low load; with no diesel exhaust in the cavern and tunnels, ventilation load fell. The parallel system served the main construction stages with ample air at peak times.
