Client: PPL Montana
Location: Great Falls, Montana
Description: Morony Hydro power plant, owned by PPL Montana, is a 50MW hydroelectric power plant in Great Falls, MT. The two 35MW generators (each is turbine limited to 25MW), produce power at 13.8kV which is stepped up to 100kV on a radially fed transmission line. At an approximate age of 100 years, the plant was in dire need of updates. NEI’s scope was to design the retrofit of the control and relaying panels within the control room. The panels had been previously ordered, but none of the engineering around connecting the panels had been completed.
The existing drawings for Morony were either non-existent or had not been updated in decades. This necessitated many site visits for as-built work to be completed. When it would come time for the panels to be installed, PPL wanted to minimize the plant downtime, so much work had to be scheduled and planned in such a way as to keep the generators running.
The project was carried out in two phases. Phase 1 was to design a temporary interconnection of the new relay panels with the existing equipment (breakers, CTs, and transformer). One generator panel was replaced at a time so that the other could remain running. Phase 2 was completed once the new breakers, switchgear building, transformer, and transmission line were installed a few months following the completion of Phase 1. This phase required removing temporary wiring and connections and providing a finalized design and installation for the plant.
NEI’s work scope included as-builting the existing panel wiring, designing new panel interconnections, generating a final set of AutoCAD drawings, providing protective relay settings (SEL, GE, Beckwith), switchgear testing, final installation, and commissioning/startup services.