Load-following operations of VHTR gas-turbine cogeneration system for developing countries

Abstract

This paper presents an original control system design that enables electrical load-following with GTHTR300C, a nuclear gas turbine cogeneration plant under development by JAEA for potential deployment in developing countries. The plant operates on a closed Brayton cycle directly heated by the helium gas coolant of a small-sized Generation IV High Temperature Gas-cooled Reactor (HTGR), also known as Very High Temperature Reactor (VHTR). The control system is designed to follow daily electric load by taking advantage of the unique operation characteristics of the nuclear reactor and closed cycle gas turbine and the direct interface of the nuclear heat source and gas turbine engine. The control system integrates several fundamental control methods and permits wide-ranging load follow at constant reactor power and high thermal efficiency, which maximizes plant economics. Control simulation of the overall plant system to follow daily load changes representative of developing countries are performed using a system analysis code in order to demonstrate a technical feasibility of the system. The observable operation parameters essential to the system control are identified that include reactor outlet temperature, turbine inlet temperature, gas turbine rotational speed, and so on. The simulations results show that the load-follow can be effectively carried out by monitoring these parameters and controlling them with suitable control apparatus. Copyright © 2012 Gas Turbine Society of Japan.