Bidirectional Proportional Multi-SOGI Based OCC for LV PV-STATCOM with Trapezoidal Modulation

This paper focuses on an improved controller configuration for active filter with its LV DC-bus directly connected with PV-modules. The power circuit consists of two full bridge inverters connected with a transformer and LC filter. The first full bridge is modulated with trapezoidal modulation to reduce the switching losses in the converter. The second full bridge is controlled through modified one cycle controller (OCC) for achieving grid voltage sensor-less operation. An proportional Multi-SOGI controller within one cycle controller ensures bidirectional active power exchange between PCC and grid, excellent grid current quality irrespective of the presence of non-linear and reactive load at the point of common coupling (PCC) and the additional harmonics generated by the trapezoidal modulation. However, the determination of phase angle information of the trapezoidal modulating signal and the adjustment of the resonant peaks at appropriate frequencies for Multi-SOGI controller requires the information of grid voltage. The grid voltage sensor-less operation is ensured through a proposed grid voltage estimator. A conventional PV-MPPT algorithm ensures the required DC voltage reference for the converter. The detailed simulation study of the proposed solution and experimental verification from an scaled down active filter prototype are presented.