Grid-connected inductor design of static var generator for photovoltaic system

Abstract

With the access of high-proportion photovoltaic power stations and the development of high permeability power electronic power systems, the problem of distributed photovoltaic access voltage over-limit and power factor is becoming more and more prominent, and the static var generator (SVG) is an important equipment to solve this kind of problem. As a key component of the static var generator, the connecting inductor has the functions of storing energy, bidirectional feeding, adjusting the phase of the output current, and suppressing the high-order harmonic current. It not only affects the dynamic and static response of the device but also restricts the output power, power factor, and DC side voltage of the SVG. At present, the parameter selection of SVG connection inductance is from the perspective of harmonic characteristics and economy, and there is no actual theoretical calculation basis. From the perspective of SVG output capacity and modulation ratio, the upper limit of the value of the connection inductance is derived. Combined with the traditional lower limit of the inductance when the harmonic suppression condition is satisfied, a design method of SVG connection inductance is given. Finally, the simulation results show that the connection inductance value designed by this method is correct and reasonable.