Kalman Filter for Reducing Total Harmonics Distortion in Stand-alone PV System

Abstract

The use of photovoltaic (PV) systems has increased steadily in the last few years due to the high demands on clean energy in different daily usages. However, the delivered power is still unstable most of the time due to the constant changes in the weather conditions. The fluctuation in the solar irradiance creates harmonics in the generated power that might leads to undesirable performance of PV system. Total harmonic distortion (THD) is the most common way that has been used as an indication of how much distortion the signal has. In order to reduce THD in the output power signal from PV systems, different techniques such as maximum power point tracking (MPPT) and power electronics connection topologies such as multi-level inverter (MLI) and control strategies such as variable duty cycle pulse width modulator (PWM) have been used. Despite all the progress that has been, the output signal still suffers from THD. This paper presented a new method of THD in PV system using Kalman filters. The distorted output current signal from a single-phase stand-alone PV system was processed by Kalman filter before it is delivered to the load. The obtained results showed that Kalman filter is very effective in term of THD reduction. It reduces the accumulated THD from 19.8% up to 3% based on the value of the covariance matrices of the process and measurement noise (tuning variable).