Research on the reactive power algorithm of PV power generation system during transient fault process

Low voltage ride through (LVRT) ability is the most important indicators of photovoltaic (PV) power generation unit grid-connected performance. At present, most of the important standards in the world require that PV power unit must have LVRT ability, and part of the standards demand that PV power generation unit should have reactive power support capacity as well, in order to maintain grid voltage amplitude stability. LVRT is a transient process; however, the reactive power algorithm is different from the traditional static reactive power algorithm during transient process. Using Matlab software, this paper researches on the reactive power algorithm, based on PV power generation unit in the process of the LVRT. This paper simulates the triangle method, Fourier transform method and instantaneous reactive power algorithm, IEC61400-21 in reactive power algorithm, combined with the actual PV power generation unit in low voltage through current and voltage data. In a result, the paper compares the simulation results, and put forward the suitable algorithm of reactive for PV power generating unit in the process of LVRT.