Power Quality Management of PV Power Plant with Transformer Integrated Filtering Method

This paper presents a new solution of power quality management for the photovoltaic (PV) power plant with the transformer integrated filtering method. The PV power plant contains two-stage filtering station, which consists of a box-type transformer with integrated filter and a 110 kV grid-connected transformer based on inductive filtering method. The filtering reactor can be integrated into the box-type transformer as a decoupled winding, so that the modular design of the box-type transformer and the fully tuned filter is realized. Inductive filtering method applied in the grid-connected transformer not only improves the power quality at the point of common coupling, but dampen the harmonic resonance between the passive filter and grid. The hierarchical structure of the PV power plant is introduced firstly. Then, the equivalent circuit model and the mathematical model of the primary and secondary filtering stations are established, respectively. Moreover, the influence of the weak coupling of integrated reactor on the filtering performance is analyzed. At last, the site tests of the PV power plant with transformer integrated filtering method are made, which show that the PV grid-connected system comprised of the two-stage filtering station has the characteristics of low harmonic emission, high power factor and stable operation.