Fractional Order Notch Filter for Grid-Connected Solar PV System with Power Quality Improvement

In this project development of Fractional Order Notch Filter (FONF) for a grid-connected solar photovoltaic (PV) system is proposed. The developed FONF control approach is used to estimate fundamental active constituents from the distorted load currents and hence gating pulses for operating Voltage Source Converter (VSC) are used in the PV system. 

This control approach for the grid-connected solar PV system is designed to achieve several purposes such as feeding active power demand of load/grid and counter current related power quality issues at common connecting point. The power quality issues taken into consideration are harmonics distortion, reactive power burden on the system and unbalancing of connected loads. 

The FONF based control proposes a modified structure of an integer order notch filter. The integer order filters have limitation due to fixed integrator and differentiator term. In FONF, the power of integrator used in a notch filter, can be modified according to the application required for obtaining accurate response of the system. Simulation results are obtained for steady state and unbalanced loads with variation in solar irradiance. The harmonic distortions in the system are observed as per the IEEE-519 standard.

Key Words — Solar photovoltaic generation, fractional order control, notch filter, harmonics, power quality.