Turnkey Solution for Single-phase Grid-connected DC/AC Converter Controls

Abstract:
As renewable energy becomes more important for today’s energy supply, the demand for efficient and cost efficient inverters for photovoltaic applications keeps on increasing. It is essential for those inverters to be able to adapt to a wide range of loads at high power factor, to provide active and reactive power, as well as synchronizing with the grid smoothly. This paper introduces a set of control algorithms for both island and grid mode for the DC/AC part of a two-stage inverter for photovoltaic panels. The control was implemented on a Field Programmable Gate Array (FPGA), featuring a PR-controller and a highly adaptive PLL based on a Second Order Generalized Integrator (SOGI). The paper also discusses ways to discretize said structures for further implementation.