Aiming at low stability and high harmonic distortion of the traditional phase-generated carrier(PGC)demodulation algorithm,we propose a modified demodulation algorithm for distributed strain sensing in phase-sensitive optical frequency domain reflectometry(OFDR).The proposed algorithm combines the arctangent function and differential-self-multiplying(ARC-DSM),which eliminates the effect of modulation depth and realizes the high precision strain variation measurements.Simulation results show that distortion and harmonic distortion are effectively suppressed by the ARC-DSM algorithm.The minimum variation of the measurable static strain is about 0.3μεand the spatial resolution can reach 0.2 m within 270 m range.
LIU JianfeiLI ChaoFAN XujunLUO MingmingLUAN NannanYANG Wenrong
A method based on polynomial regression algorithm(PRA) is proposed in this paper to compensate the nonlinear phase noise in optical frequency domain reflection(OFDR) systems. In this method, the nonlinear phase of OFDR systems is represented by the polynomial phase function, and then the coefficients of the polynomial phase function are estimated by PRA. Finally, the nonlinearity is compensated by match Fourier transform(MFT). Simulation results demonstrate that the proposed algorithm has good performance in compensating both weak and strong nonlinear phase noises of OFDR systems.
首先介绍三相有源电力滤波器(active power filter,APF)在abc轴系下的连续时间数学模型,并采用后向差分的方法得到在??轴系下的离散化数学模型。对于电流内环,采用无差拍控制(deadbeat control,DBC)方法实现谐波电流的跟踪。为了解决DBC的延时补偿问题,采用"两步预测"的方法预测给定电流。特别地,针对待补偿电流变化显著的时间区域提出一种电流跟踪误差补偿的方法消除网侧电流的"上凸"和"下凹"的现象。同时,采用电流校正算法抑制采样误差对电流产生的影响。最后,搭建三相APF的实验平台,验证所提出控制方法的有效性。
