Speed Control Method for Turboelectric Power Generation Systems

In association with NASA Glenn Research Center and Lockheed Martin Space Systems, Honeywell has developed and successfully tested an electric power generation system that uses non-toxic hydrogen and oxygen propellants that are reacted catalytically. The resulting fuel-rich gases drive a turbogenerator.

Speed control of this system is challenging due to highly variable electric load profile. Discrete two-position valves were used to control the propellant flow for improved reliability compared to proportional valves. This “bang-bang” speed control method exhibits variation in turbine acceleration and deceleration with load. The control thresholds for the turbine speed are adjusted based on load so as to compensate for increased speed overshoot and undershoot. The benefit achieved in this speed control method is about a 20 percent improvement to a speed control performance index, which results in a 4 percent reduction in the system weight, and 4 percent lower propellant consumption at maximum power.

A brassboard unit incorporating many of these features was tested. It produced 270-Vdc output at power levels ranging up to a peak load of 139 kW.