Solar energy used for grid connection: a detailed assessment including frequency response and algorithm comparisons for an energy conversion system

Abstract

To help reduce losses in a distributed generation system, this article proposes a suitable method involving a three-phase multifunctional grid-connected solar energy conversion system (SECS). A two-stage circuit topology is used in this work; the first stage is a boost converter, which serves the purpose of maximum power point tracking (MPPT), and the second stage is a four-leg voltage source converter (VSC), which serves the purpose of feeding extracted energy along with improving power quality in the distribution system. The SECS not only feeds solar photovoltaic (SPV) energy into the grid but also acts to balance grid currents, compensate for reactive power, eliminate harmonics, and mitigate neutral current. A feedforward term for the SPV contribution is used to improve the dynamic response for climatic changes. The PV array voltage is continuously adjusted with the help of a boost converter to achieve MPPT, whereas the dc-link voltage of the VSC is kept constant using a proportional-integral (PI) controller. A second-order generalized integrator quadrature (SOGI-Q)-based algorithm is proposed for the control of a four-leg VSC.