Sampling rate conversion and data synchronization in big merging unit

In order to achieve multirate sampling conversion and Data Synchronization (DS) for multi-channel data from Electronic Instrument Transformers (EITs) in power system when the sampled data are outputted to IEDs, Big MU scheme has been proposed. Big MU consists of modules of MUs, multirate conversion and DS. Sampling data of MUs from EITs get through multirate conversion module including interpolation, low-pass FIR filter and decimation to obtain the desired sequence values. However, the multi-channel data after conversion are asynchronous with a unified frequency; DS module is utilized for syncing the asynchronous data. The experimental result shows that the scheme can achieve sampling rate conversion and satisfy the requirement of each harmonic component´s amplitude precision in the IEDs by using module of DS in Big MU.