Nobuo Okita

Development and Strategy for A-USC Steam Turbine Cycle

Efficiency improvement of thermal power plants is one of the key technologies to protect the global environment because of lower emission gas. There are many approaches in this regard, which are investigated and developed around the world. Thermal efficiency of fossil power plants has been improved by raising steam temperature as high as 620 C in a realization of Ultra Super Critical (USC) steam turbine system. In order to enhance the thermal efficiency further, we are developing the Advanced Ultra Super Critical (A-USC) steam turbine system using high pressure and high temperature steam of 700 C or over 700 C. The main focus of the Research & Development of A-USC steam turbine is the verification of the alloys for the large rotor, casing and valve components, and the main issue for application to the power plant is an economical aspect and field of technology for the realization of such steam conditions with cost-effectiveness, for instance, optimization of cycle heat balance, turbine design, welding technology and so on. This paper describes briefly about R&D results of A-USC steam turbine and suggests an economical strategy in order to make it possible to be realized sooner.© 2011 ASME

Power output smoothing for hybrid wind-solar thermal plant using chance-constrained model predictive control

Fluctuating wind power must be smoothed before supplied to a power grid in order to prevent potential damages of sensitive electrical devices connected to the grid. This paper considers a hybrid wind-solar thermal plant, where the output from the wind turbine is smoothed by bypassing through the thermal plant. We propose a chance-constrained MPC-based control method that optimally decides the ratio of the wind output that is bypassed through the thermal plant so that the rapid fluctuation of output is suppressed while the direct power output is maximized. The controllers parameters are designed in a way that result in a Pareto-optimal performance. We demonstrate the performance of the proposed method through simulations using real data.

Proceedings of the IEEE Conference on Decision and Control

Fluctuating wind power must be smoothed before supplied to a power grid in order to prevent potential damages of sensitive electrical devices connected to the grid. This paper considers a hybrid wind-solar thermal plant, where the output from the wind turbine is smoothed by bypassing through the thermal plant. We propose a chance-constrained MPC-based control method that optimally decides the ratio of the wind output that is bypassed through the thermal plant so that the rapid fluctuation of output is suppressed while the direct power output is maximized. The controllers parameters are designed in a way that result in a Pareto-optimal performance. We demonstrate the performance of the proposed method through simulations using real data.