Power Quality Improvements in SPV System Operating with Weak AC Network

Abstract

The problems associated with the weak AC network such as unbalanced voltages and distorted load currents create challenges in the operation of the grid interfaced solar photovoltaic (SPV) system. It distorts the AC network currents and causes the flow of the negative sequence currents in the network. Hence, the negative sequence currents and harmonic currents flow in the network. In this work, an adaptive algorithm is presented to smooth the power flow to the AC network even the load and voltages are unbalanced or distorted. In this work, a single step size normalized subband adaptive filter (NSAF) is used to filter the sensed load currents. An adaptive DC link control is used to regulate the DC link voltage. It ensures that DC link is regulated according to the maximum of phase voltages peak, which is also estimated by the same NSAF algorithm. In this work, the second order generalized integrator (SOGI) algorithm is used to evaluate the positive sequence voltages and an incremental and conductance (INC) based algorithm is used to maximize the efficiency of the SPV system. The effectiveness of the presented control algorithm is validated under various operating conditions.