基于拉格朗日一次插值的船舶故障录波时间同步

Time synchronization of ship fault recording device based on Lagrange once interpolation

针对外部时钟同步法在船用条件下存在的难以实施、易受干扰、安全性低等问题,提出一种基于插值算法的船舶故障录波时间同步方式。首先,录波主机从合并单元上传的报文中提取出原始采样值和额定延时信息;然后,经时间修正还原真实的采样时刻;最后,利用拉格朗日一次插值运算得到同步时刻的重采样值。Matlab仿真实验表明,幅值误差可以通过适当提高采样频率的方式降低,相位误差对应的等效时延均不超过2μs;样机实验结果显示,正常条件下有效值误差不超过±0.01%,加入故障信号后,基波和5次谐波的有效值误差分别低于±0.006%和-0.5%,两种情况下的等效时延均不超过-3.5μs,同步精度达到了IEC61850规定的T4等级。

Aiming at the problem that the external clock synchronization method is difficult to implement, susceptible to interference and insecure under the marine condition, a time synchronization method of ship fault recording device based on interpolation algorithm was proposed. Firstly, the recording host extracted the original sampling values and the rated delay information from the packets uploaded by the merging units. Secondly, the real sampling time was restored after time correction. Finally, Lagrange once interpolation operation was used to obtain the resampling values at the synchronous time.Simulation on Matlab shows that the amplitude error can be reduced by increasing the sampling frequency appropriately, and the equivalent delay corresponding to the phase error is not more than 2 μs. Prototype test shows that the error of valid values does not exceed ± 0. 01% under the normal condition, of which the fundamental and 5th harmonic are less than ± 0. 006%and-0. 5% after adding the fault signal. Moreover, both of the equivalent delays are less than-3. 5 μs, and the synchronization accuracy is in accordance with the T4 level specified in IEC61850.