翻译 控制系统改造新.docVIP

Summary The availability of powerful first principles type models designed for PC-based computer hardware provides a simple and effective tool for the study of transients within power plants. All of the essential components of the plant including the controls can be modeled and the behavior of the plant to various transients can be evaluated. This paper will address the use of such a dynamic model to design an improved control strategy for pulverized coal fired drum type boilers connected to single reheat type turbine generators. Comparisons with the current techniques will be used to quantify the benefits and demonstrate the simplicity of the control methodology. Introduction Utilities in North America are faced with a declining margin between installed capacity and electrical demand. Consequently, a greater proportion of units are required to participate in middle load and peaking duty. This applies to the larger, more efficient plant and older, smaller units which previously were base loaded. A utility’s ability to meet the system demand in the most cost effective manner will be, to some degree, dependent on the load range and maneuverability of the individual units. The unit efficiency under cycling duty will depend on the degree to which boiler and turbine efficiencies can be maintained over the operating load range. The parameters which can affect the unit efficiency during cycling operation or limit the unit’s capability to cycle are: 1. Pressure and temperature control to the turbine 2. Extent of overfiring/underfiring in the boiler 3. Excess air and exhaust gas temperature leaving the boiler The paper will discuss new control techniques which address the above parameters and thereby provide improvements in load cycling capability and efficiency of coal fired thermal power plants. The control system described is conventional in nature and does not incorporate or involve the use of advanced control concepts, artificial intelligence techniques, or “expert” typ