Abstract:

Taking the induced draught fans of the 300MW unit in Tianjin Huaneng Yangliuqing Thermal Power Company Limited as example, the relative logic and

functions of the automatic control system after reformation of variable frequency control system for the induced draught fans were introduced. Some problems

were existed in the variable frequency control system, which including that the adjustment speed of the frequency converter is faster than electric actuator

of the fan inlet damper adjustor, and when one of the two fans is driven by frequency converter and the other is driven by 50Hz power source, there are not

automatic balancing and deviation rectification functions in the original control system. In order to solve above problems, the electric actuator of the fan

inlet damper adjustor was replaced, the parameters of the PID adjustor were adjusted, and the two fans automatic balancing function and deviation

rectification logic were added into the system. The static and dynamic tests and practical operation show that the improvement of the variable frequency

control system achieves expect goal, the induced draught fans operate more economically and reliably.

Key words: power plant, variable frequency controlled fan, automatic balance, deviation rectification, control system, energy saving and emission reduction