Abstract
Along with the increase in the share of the total electric power system held by thermal power plants, the increase of capacity of individual units and the trend towards higher steam pressure and temperature are also remarkable. In this situation, the improvement of functions and abilities of the plants like quick startup, shutdown and the safety of operation are becoming much more important. Especially in Japan, problems related to plant startup where a complicated procedure is involved and the system characteristics are not always made clear are being given serious consideration. In this case, the application of a highly efficient computer control system is expected to be the most effective.
The paper deals with the development of a direct digital control (DDC) system for steam turbine startup, which is one of the most important procedures of the thermal power plant operation. The steps and results of the development are as follows.
(1) The optimal scope to be automated by DDC was decided after analyzing the plant operation procedures, and the computer control systems suitable to this control were planned.
(2) The dynamic equations of the systems were derived and the control problems were extracted and analyzed. Then control systems with advanced functions like adaptive control were developed for solving the problems.
(3) The systems were simulated by a digital simulation technique, and the control characteristics of the systems at various operational conditions of a plant were analyzed.
(4) The control systems were applied to an actual plant, and their high performance was demonstrated.
As a result, a realistic turbine startup DDC system was brought to completion, and so safe and long-life operation of turbines can be expected.
