New Orleans Sewerage & Water Board

BRINGING A MORE THAN 100-YEAR-OLD SYSTEM INTO THE AGE OF TECHNOLOGY

The New Orleans sewerage, water, and drainage system is one of the oldest in the country, and when it was first built at the turn of the century, it was arguably the world’s most advanced, efficient drainage infrastructure – one that served as a model for other cities around the world.

Over the decades, the once-revolutionary drainage system has been outpaced by technological advances. Learning from the past and taking a cue from the then engineering innovation, a new master plan has been adopted to upgrade the system. But a system that is more than a century old, and land-locked by a growing municipality presented unique challenges.

Maintaining a 25Hz generating system has been costly and challenging due to the age of all 25Hz generating equipment. The existing 25Hz system is powered by a gas turbine generator, and a steam turbine generator with an aging steam boiler plant.  As part of the Sewerage & Water Board’s master plan, a new utility substation is being installed and required the design of three new static frequency converters that would convert the purchased 60Hz electric power – provided by the utility – to the 25Hz power many of the city’s drainage pumps are equipped to handle.

Implementing the converters into the existing power system presented a significant challenge due to system stability concerns, multiple operating scenarios and an antiquated operating control system.  The system must be designed to provide flawless operation during a varying load demand typically experienced with unpredictable weather.

Combining The Old With The New

Along with Walter J Barnes Electric, Siemens, QDS and Point8 Power, MSB helped to develop a full functioning static frequency converter system to help convert new utility and existing generator 60Hz power to 25Hz power for the citywide drainage system.

The system is designed to be bi-directional and must operate from either utility provided power or from onsite generators. Additionally, the convertor system is designed to auto-start and auto-synchronize with other power sources for seamless transition upon increased power demand.  Due to the nature of variable frequency drive technology, power system stability is critical for proper and safe operation. MSB helped the project team overcome several major obstacles during the project design phase.

MSB provided technical guidance for integration of the converters to the existing electrical system at the SWBNO. As part of this effort, MSB performed system stability calculations to determine the proper design parameters for implementation of the new systems. MSB also supported the design of several key components necessary for stabilizing the power system and protecting the key components. Such components include power control equipment, RC filters and a dynamic braking system.

As part of the new operational goals of the SWBNO, MSB helped with the design and implementation of a new Power Distribution Control System allowing for full control of the system by the remote central operators.

MSB’s technical guidance has been instrumental in providing a safe and secure design. As a result of the project team’s efforts, the new static frequency changers will operate successfully with little impact to the stability of the existing power system.

With the implementation of the new system, the city’s drainage system will be powered more securely and reliably and will provide redundancies to significantly reduce the risk of system power outages.