周期电气信号测量中软件同步采样方法的研究

软件同步采样是周期电气信号微机测量中最常用的采样方式,但它采样的同步精度和时间间隔均匀程度都不够高,影响测量精度.通过对软件同步采样实现过程的分析,找出了影响采样同步和导致采样间隔不均匀的主要原因,并提出了三个相应的解决方法.方法一是在采样过程中动态调整采样时间间隔,使实际采样时刻最大限度地逼近理想均匀同步采样时刻;方法二是在采样后用线性插值方法修正采样值,使实际采样序列逼近理想的均匀同步采样序列;方法三是实时跟踪测量信号周期和校正采样周期.三种方法均具有计算量小,易于实现,实用有效的特点.对电功率和谐波测量的仿真分析结果,证实了所提方法对提高微机测量精度的有效性.

Research on Software Synchronous Sampling in Measurement of Period Electric Signals

Synchronous sampling by software is commonly used in digital measurement of period electric signals. However,it always introduces uniform errors and synchronous errors that degrade the measuring accuracy. The traditional methods of synchronous sampling by software are examined and the factors that cause uniformity errors and synchronization errors are found out. Three novel methods desined to minimize these errors and improve measuring accuracy are proposed. The first adjusts the sampling time-intervals dynamically so that the sampling moments approach the ideal ones. The second modifies the actual samples toward an ideal sampling sequence by means of linear interpolation algorithm. The third evaluates the signal fundamental period in real-time and modifies the sampling period. All the methods are easy to realize and achieve a noticeable improvement of measuring accuracy,with a moderate increase in computational cost and measurement responding time. The results of the simulation of both active power and harmonic measurement show that proposed methods are feasible and effective.