火电厂风机系统低电压穿越解决方案

Solution of Low Voltage Ride Through of Fan System in Thermal Power Plant

针对火电厂风机系统无速度传感器V/f控制的高压变频器,提出了一种按失电时间分别测量定子剩磁电压或将定子电流矢量分解的转速估算方法,从而实现转速跟踪再启动。对该方法进行了全系统的Matlab仿真和分析。研究表明,该方法能在1-2 s内准确跟踪风机转速,并迅速使转速恢复正常,实现系统低电压穿越,防止因变频器低电压保护造成火电机组停机、甚至大范围停电等事故。

In order to realize flying restart,a new speed estimation method based on stator residual magnetism voltage or the vector decomposition of stator current determined by power losing time was proposed,which aimed at high-voltage inverter using speed sensorless V/f control in thermal power plant fan system. Then,the whole system was simulated and analyzed by Matlab. Study shows that this method can track the fan speed precisely in 1~2 s and make the speed return to normal fast. Low voltage ride through is achieved and thermal power unit downtime or widespread power outages caused by the converter low voltage protection is prevented.