典型PLC电压暂降耐受性能实验研究

Research on Tolerance Characteristics of Typical PLC to Voltage Sags

PLC(可编程逻辑控制器)被视为一类典型的电压暂降敏感设备。考虑到PLC技术更新及国内相关实验工作较为缺乏等现状,首先分析了PLC电源模块与输入/输出模块电路结构,指出PLC暂降耐受性能主要由电源与输入模块决定,而市电等级成为影响PLC暂降性能的因素。然后搭建测试平台,选取国内外8个主流PLCs,考察电压暂降幅值与持续时间对PLC电源模块、输入模块耐受性能的影响程度。通过对实验数据进行极值化处理和限值曲线"矩形化",确定了典型PLC暂降耐受能力范围。与早期结果比较,目前PLC暂降耐受能力的不确定区域减小,可应用于更精确的影响评估工作中。此外,实验还发现直流侧电容容量过小,不仅使PLC暂降耐受能力降低,而且更容易使PLC出现不确定性运行状态,即输入/输出端口电平发生多次跳变。

PLC（ Programmable Logic Controller） is considered as a kind of typical sensitive equipment to voltage sags. Given the renewal rate of PLC technology and the shortage of related experimental researches in domestic,this paper firstly analyzed the circuit structures of PLC power supply and its discrete input/output modules. And then the paper pointed out that the tolerance of PLC to voltage sags was mainly determined by power supply and the input module. And different values of rated working voltage need to be considered as a factor. The authors built a test platform and chose eight typical PLCs both at home and abroad to test the tolerance performances of power supply module and discrete input module to voltage sags in different voltage sag magnitudes and duration. After extremum processing the experimental data,the authors obtained the sensitivity curves of PLCs and identified the tolerance range of the typical PLC sag. Compared with the early results,the uncertain area was diminished and could be applied to the more accurate influence assessment of PLC. Furthermore,it was found that the over-low capacitance on DC side not only caused PLC to be more sensitive to voltage sags,but also may lead PLC to work in an uncertain state,which means the DI/DO levels may jump frequently.