New method for controlling large fan of thermal power plant boiler using inverter in abnormal state

This paper presents a new air flow controller for a thermal power plant. When an inverter power source is used for a forced draft fan (FDF) in order to save power, the conventional counter measures do not caver all in abnormal state. The proposed controller is evaluated by performing a simulation. It is clarified that the power source is changed from the inverter to a commercial power source within 0.5 s in abnormal state. The changing time is decided 0.55 s by a mechanical permission of design. When testing is carried out in an actual plant by using the proposed controller method, a transient response is compared with simulated and measured data. The errors are less than 3.4%. Furthermore, the FDF changes over smoothly and the plant condition keeps as same as normal state in the actual plant testing. This paper deals with the safe operation of a thermal power plant that employs the proposed air flow controller. © 2009 The Institute of Electrical Engineers of Japan.