基于MCF52235的新型低频减载装置的设计研究

Design and research on a novel UFLS device based on MCF52235

在传统低频减载保护装置中由于技术的局限性,采用一段时间内的频率变化平均值表示实际的频率变化率,导致保护动作的速动性能降低,为杜绝上述现象,设计了一种基于MCF52235的新型低频减载装置。该装置借助MCF52235具有输入捕捉能力的DMA定时器模块捕捉被测信号的跳变脉冲沿,由内部计数寄存器和捕捉寄存器配合记录一个周波内标频脉冲个数N,再通过相应的软件算法计算出被测信号频率及其变化率,消除了平均计算导致的偏差。测试结果表明,该装置在系统频率降低时可及时准确动作,并能有效地防止异常情况下所导致的低频减载误动作。

Limited by the techniques in the traditional protection device of under frequency load shedding（UFLS）,the frequency change rate is always representes by an average value in a time segment.In order to put an end to the above phenomenon,the paper designs a sort of novel UFLS device based on MCF52235.By means of the module of DMA timer that owns input capture ability,the new device could capture the jump step pulse edge of the measured signal.Combined inner timer counter register with capture register,it could record the standard pulse number during a cycle.And by use of corresponding software algorithm,it could work out the measured signal’s frequency and its change rate.Therefore the deviation resulted from average computing could be eliminated.The test result shows that the device can accurately act in time when the system frequency is reduced,and can effectively prevent wrong action of under frequency load shedding in abnormal cases.