A fixed normalized LMF (XE-NLMF) algorithm for single stage grid interfaced solar PVSystem

This manuscript presents the analysis and design of a fixed normalized least mean fourth (XE-NLMF) based algorithm for a single-stage, three-phase grid-integrated solar photovoltaic (SPV) system. The SPV system comprises a solar PV array, a voltage source converter (VSC), a three-phase utility, and a combination of linear and nonlinear loads. The conventional least mean fourth (LMF) algorithm is known for its lower steady-state error and enhanced stability in noisy environments. However, the proposed XE-NLMF algorithm demonstrates superior steady-state performance compared to the conventional LMF technique. In this study, an SPV array coupled with the perturb and observe (P&O) method for maximum power point tracking (MPPT) is integrated with a VSC-based converter controlled using the XE-NLMF algorithm, interfacing with a three-phase utility. The performance of the proposed VSC-based controller is evaluated in a MATLAB simulation environment under various operating conditions, including changes in solar insolation levels, load unbalancing, grid weakness, and different load combinations (linear and nonlinear). Finally, the novelty lies in the stability of the proposed controller, which is assessed by using (i) Time Domain State Space System Generation, (ii) novel pole-zero analysis technique, (iii) Stability using Impulse response from Inverse Transform, (iv) in the Z-domain by using Lypaunouv Stability analysis and by normal Zdomain analysis to realise the real time analysis by stability analysis. Moreover, the proposed controller ensures compliance with IEEE-519 standards by maintaining power quality and limiting harmonic distortions.