One signal processing method of OCT based on colored noise extended Kalman filter

Jingru Zeng,Yansong Li,Jun Liu,Yansong Wang

doi:10.1051/matecconf/201823201009

Jingru Zeng, Yansong Li + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/201823201009

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Abstract

When an optical current transformer is used to measure current, its output signal is mostly non-linear and contains colored noise; on the other hand, when the power system is in steady state operation, the frequency is not stable. This paper proposes an optical current transformer signal processing method based on colored noise extended Kalman filter which can reduce the measurement error caused by colored noise and realize frequency tracking. The following two cases are considered: 1) the dynamic noise is colored noise; 2) the observation noise is colored noise. In these two cases, the corresponding formulas of the proposed method are analyzed and derived. Simulation results showed that the extended Kalman filtering method based on colored noise can effectively filter the colored noise, and the output waveform and output error obtained by this method are improved effectively.

Highlights

As a sensing element of the primary system, the current transformers are the data source of all relay protection devices and electric energy metering devices, which requires the high output precision of current transformers [1,2].Compared with traditional current transformers, the optical current transformers based on Faraday Effect have s series of advantages, such as strong anti-electromagnetic interference ability, good insulation properties and large dynamic response range[3]
Based on the above problems, this paper presents a signal processing method of optical current transformers based on colored noise extended Kalman filter, and deduces the extended Kalman filtering formula of the nonlinear system in two cases of colored state noises and colored observation noises
When the power system is in normal operation, the output signals of the optical current transformer are mostly nonlinear, and there are problems such as frequency fluctuation and noise color

Summary

Introduction

As a sensing element of the primary system, the current transformers are the data source of all relay protection devices and electric energy metering devices, which requires the high output precision of current transformers [1,2]. In order to solve these problems, Kalman filter is usually used to process the output signal of the optical current transformers. In the operation of the power system, most of the systems are nonlinear, and the output of the optical current transformers include some colored noises, such as 1/f noise, integrated noise and sinusoidal noise[6]. Considering the nonlinear problem of system, T Zou presented an unscented Kalman filtering method which used the observation information expansion method to modify the colored noises[8]. Based on the above problems, this paper presents a signal processing method of optical current transformers based on colored noise extended Kalman filter, and deduces the extended Kalman filtering formula of the nonlinear system in two cases of colored state noises and colored observation noises

The functional model of extended Kalman filter method is

Extended Kalman filtering method with colored state noises

Extended Kalman filtering method with colored observation noises

Experimental results and comparison

DC component

Conclusion