引风机变频器低频过流原因的分析与处理

Cause Analysis and Treatment of Low Frequency Over-Current of Induced Draft Fan Inverter

我厂3号、4号炉引风机(电机功率2 100 kW)原设计为工频(50 Hz)固定转速运行方式,当机组负荷变动时,可通过调节入口静叶开度实现风量控制,此方式会造成巨大节流损失。为减少引风机节流损失,保证机组负荷变动对风量的要求,将引风机改造为V/F控制模式的变频器运行方式,采用入口静叶全开的模式,改变变频器频率实现风量控制,此种运行方式下,频率在45 Hz左右时,变频器经常出现输出超过电机额定电流。本文介绍了引风机变频器的控制方式及产生输出过电流的原因及处理方法,该方法使变频器能够达到额定频率50 Hz且输出不超过电机额定电流,可在变频控制的引风机、一次风机等类似系统推广应用。

The No.3 and No.4 induced draft fans with motor power of 2100 kW are designed to operate at a constant speed of 50 Hz.However,as the load of the units changes,the air volume must be adjusted by modifying the opening of the inlet stator blades.In order to reduce the throttling loss of the induced draft fan,it is essential to control the air volume precisely.To accomplish this,the operation mode of the frequency converter that controls the induced draft fan is modified to fully open the inlet static blade,while controlling the air volume through adjustments in the frequency of the inverter.Although this approach is effective,the output current of the inverter may surpass the rated current of the motor when the frequency reaches approximately 45 Hz,causing over-current.This paper addresses the control method for the induced draft fan inverter,the causes of over-cuirent,and the applicable treatment method.By utilizing this solution,the inverter can be operated at a maximum frequency of 50 Hz without surpassing the rated current of the motor.This model can be propagated for use in the induced draft fan,primary fan,and similar systems that are controlled by frequency conversion.