基于新息加权自适应UPF算法的智能变电站PTP主时钟源校准新方法

A Novel Calibration Method for the Master PTP Clock in Smart Substations Using New Information Sequence Weighting and Adaptive Unscented Kalman Particle Filter Algorithms

为解决传统秒脉冲(pulse per second,PPS)钟差信号的处理未考虑GPS秒脉冲跳变野值及主时钟源晶振温度变化、晶体老化造成的非线性误差影响等问题,首先对智能变电站精确时间协议(precise time protocol,PTP)主时钟与GPS输出的PPS钟差信号进行了数学建模,然后基于新息加权自适应无迹粒子滤波算法对PPS钟差信号进行滤波处理,最后将处理后的钟差信号送入PID控制器,生成晶振频率调整信号,实现PTP主时钟源的校准。无迹粒子滤波(unscented Kalman particle filter,UPF)算法可对主时钟源因老化而产生的频率非线性漂移进行校正,引入新息序列加权技术可对GPS秒脉冲信号中跳变野值进行处理,自适应滤波技术则可减少系统噪声对于滤波结果的影响,增强时钟源校准系统的鲁棒性,从而提高校频精度。经仿真验证表明,与传统钟差信号处理算法相比,所提方法将钟差信号的处理误差减小了55.96%,且在跳变野值处的钟差处理误差减小了76%以上,从而将PTP主时钟源校准系统中频偏量测误差由3.635×10;Hz降低至9.59×10;Hz,最终将PTP主时钟源频率稳定度提升了2个量级。

To improve the stability and accuracy of precise time protocol(PTP)master clock source in smart substation,the traditional calibration method of PTP master clock source usually uses the Pulse Per Second(PPS)clock difference signal output by GPS and PTP master clock to generate crystal frequency adjustment signal,according to which the PTP master clock source is calibrated.The traditional clock difference signal processing does not take into account the jump outfield of PPS,the nonlinear error caused by the crystal temperature change,and the crystal aging of the master clock source.To solve the above problems,this paper firstly conducts mathematical modeling for PPS clock difference signal output by PTP master clock and GPS and then conducts filtering processing for PPS clock difference signal based on new information sequence weighting and adaptive Unscented Kalman Particle Filter(UPF)algorithm.Finally,the crystal frequency adjustment signal is generated from the processed clock difference signal by the PID controller to realize the calibration of the PTP master clock source.The UPF technology is used to correct the master clock source frequency nonlinear drift due to aging,introduce new information sequence weighting technology can process jump outliers of the GPS second pulse signal,adaptive filtering technique can reduce the noise influence on filtering result,enhance the clock source calibration system robustness,and improve frequency precision.Simulation results show that compared with the traditional clock offset signal processing algorithm,the algorithm in this paper reduces the clock offset signal processing error by 55.96%,and the clock offset processing error at the jump outfield value by more than 76%,thus reducing the intermediate frequency offset measurement error of the PTP master clock source calibration system from 3.635×10–10 to 9.59×10–12.Finally,the frequency stability of the PTP master clock source is improved by two orders of magnitude.