Abstract
The use of shunt regulators for load-following of proposed static space nuclear power systems (SNPSS) raises a number of concerns, such as the possibility of a failure in the shunt regulators requiring reactor shutdown, or the possible need to deliver somewhat higher power level to the load than originally expected. Therefore, a back-up system is needed in SNPSs to eliminate the possibility of a single-point failure in the shunt regulators, and to increase the overall system reliability despite changing mission needs and deteriorating equipment. The objective of this research is to develop a controller for the voltage regulation in static SNPSS, which is capable of overcoming system variations resulting from operation at different power levels. This is accomplished by developing several linearized models of the SNPS using a simplified, validated reference model of an integrated nonlinear SNPS model, covering its entire operating envelope. A dynamic compensator is designed using each of the linearized models based on the Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR) method. The LQG/LTR method is a systematic multivariable control system technique with several desirable properties such as nominal stability and performance, as well as stability robustness to unmodeled dynamics. The various compensators matrices, including the gain and system matrices, are fitted to a scheduling variable, namely the SNPS electric power produced, to obtain a nonlinear gain-scheduled compensator The performance of the gain-scheduled compensator is systematically investigated via transient and steady-state simulations using the integrated nonlinear SNPS model. The simulations, which include sensor noise at the plant output, demonstrate the effects of variations in the fuel temperature reactivity feedback coeficient on the load-following capabilities of the SNPS. Robustness analysis results of the gain-scheduled compensator demonstrate that the proposed control concept exhibits a significant degree of operational flexibility, and it is primarily intended for long-term space mission requiring significant levels of power system autonomy.
Onbasioglu, Fetiye Ozlem (1993). Gain-scheduled controller design for load-following in static space nuclear power systems. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1993 -THESIS -O58.