Low‐voltage ride‐through operation of grid interfaced solar PV system enabling harmonic compensation capabilities

This study presents a robust Kalman filter‐based multifunctional control strategy, to enable wide‐scale utilisation of the grid‐interfaced solar energy conversion system (SECS). The presented control technique offers multifunctional features such as unity power factor, harmonics mitigation, reactive power compensation along with ride through operation under balanced and unbalanced low‐voltage faults in the distribution grid. Under fault in the grid side area, the DC–DC converter is controlled in a way that it reduces the active power injection and restricts the inverter currents within its maximum current limit. Based on the depth of grid voltage sag, reactive power supply to the grid is adaptively adjusted, as recommended by IEEE 1547‐2018 standard. To minimise the inverter losses, adaptive DC link voltage is introduced, which adapts the DC link voltage in proportion to the grid voltages. Simulation results exhibit the efficacious of the presented robust control strategy in achieving multifunctional features such as harmonics mitigation, grid currents balancing feature and reactive power requirement, under unbalanced line to ground (L‐G) and double line to ground faults. Test results demonstrate the satisfactory performance for diverse operating scenarios such as imbalanced currents in the load side network, SECS to DSTATCOM mode and vice‐versa, and L‐G fault.