Implementation of In-loop Filter based DSC-FLL Control Approach for Power Quality Improvement in Isolated Microgrid
Sombir Sombir, Madhusudan Singh, Ashutosh K. Giri
Abstract
In this paper, a delayed signal cancellation based frequency locked loop (DSC-FLL) control approach is designed and implemented to provide improved disturbance rejection ability and rapid dynamic response with reduced steady state error. In an isolated microgrid (MG), two filtering stages are used in this control i) in-loop filter and ii) reduced order generalized integrator based FLL (ROGI-FLL). The DSC-FLL control with VSC provides voltage/frequency stabilization, active/reactive power compensation, and harmonics abatement of nonlinear loads. In this work, a solar photovoltaic (SPV) array is interfaced to the dc-link through a bidirectional converter (BDC), and a modified Perturb & Observe (P&O) technique is utilized for drawing peak power from a SPV. A Battery storage system (BSS) is utilized to maintain the power level between the renewable energy sources (RES's) and the load under intermittent condition of RES's and unbalanced loading condition. The BDC control maintains the charging and discharging of the BSS and regulates the dc-link voltage. Moreover, the BDC also removes the second harmonic from the battery charging current. The dynamic response of isolated MG is analyzed under different operating conditions.