An Enhanced Filtering Generalized Integrator-Based Control for Improved Performance of a Grid-Tied PV System at Adverse Grid Voltages

This paper deals with a single stage photovoltaic (PV) system with improved resilience against adverse grid conditions. This is majorly achieved in two ways. First, it presents an enhanced filtering generalized integrator (EFGI) based filtering stage to process the prevalent grid voltages and derive their positive sequence components free of harmonics components, unbalance, and dc offset. The presented EFGI delivers a considerable improvement over the conventional filters and helps to improve the power quality (PQ) in case of unequal or distorted voltage conditions. Second, to address large voltage dip or rise scenarios, a dual-mode mechanism is applied for the selection of the dc-link voltage (
V
_dc
) reference and the corresponding generated PV array power. At regular voltage scenario and at the availability of PV power, the reference
V
_dc
is governed by the necessity to keep the PV array operating at its peak generation levels. However, at loss of PV power or divergent grid voltages,
V
_dc
control is quickly transferred to an alternate approach, varying
V
_dc
as per the existing grid voltages. Using this, the injected currents are limited, and system desynchronization is prevented at voltage dips. The increased
V
_dc
at grid voltage rise avoids deterioration in the grid PQ. The grid PQ is also assured despite the presence of local nonideal loads. The EFGI benefits and the real-time performance of the presented system are assessed using test results.