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 countermeasures do not cover all abnormal states. The proposed controller is evaluated by performing a simulation. The power source is shown to change from the inverter to a commercial power source within 0.5 second in the abnormal state. The changing time is determined to be 0.55 second based on the mechanical tolerance of the design. Testing was performed in an actual plant using the proposed control method, and the transient response was compared with the simulated and measured data. The errors were less than 3.4%. The FDF changed over smoothly and the plant conditions remained the same as the 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. (C) 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 180(4): 47-56, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.21202