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Combined IIR and FIR Filter for Improved Power Quality of PV Interfaced Utility Grid

For enhancing the power quality (PQ), an adaptive infinite impulse response (IIR) combined with finite impulse response (FIR) control is utilized for a grid connected solar photovoltaic (PV) system. The power obtained from a solar PV array is affected due to the seasonal and diurnal variability of the sun. Moreover, the utility distribution network is relatively weak for the developing and underdeveloped countries, exacerbating PQ deterioration issues. For the improvement in PQ indices, an adaptive combined IIR and FIR filter is utilized here, which exhibits adaptive control capability of the voltage source converter essential for smart grid operations. The major advantage regarding the utilization of adaptive control involves much less sensitivity to quantization errors. This new application of a combined IIR and FIR filter includes the mitigation of harmonics in the grid currents and the grid voltages, thereby improving PQ along with reactive power compensation. Due to a combination of IIR and FIR filters, the filtering is achieved with fewer coefficients, requiring minimum memory (as in the case of IIR filters) along with easy implementation and design capability (in the case of FIR filters). Test cases corroborate satisfactory performance during the weak grid conditions, such as voltage distortion, unbalance, and swell, and experimental results are obtained though assessment on a developed laboratory prototype. The PQ improvement is evident by observing the total harmonics distortion conferring to the IEEE-519-2014 Std.