ISOGI-Q Based Control Algorithm for a Single Stage Grid Tied SPV System

This paper deals with a single stage solar photovoltaic (SPV) array tied to a three phase grid using an improved second-order generalized integrator quadrature (ISOGI-Q) based control algorithm to improve the power quality of the grid. The maximum point power tracking (MPPT) is achieved by using an incremental conductance method. The incremental conductance MPPT method is effective to extract crest power from an SPV array, as well as to control the dc bus voltage. The ISOGI-Q based control serves multifunctionalities such as load balancing, power factor correction, and improved solar power penetration into a distribution network. Test results of the ISOGI-Q based control algorithm are found to be satisfactory for improved power quality in terms of load balancing, harmonics elimination, and very effective power factor correction under various dynamic conditions such as load unbalancing, variable solar insolation, distorted grid, and imbalanced grid voltage conditions. Distributed static compensator capabilities of a photo-voltaic based system are useful to supply the active power to the load and surplus power to the grid. The control algorithm is verified on a proposed topology and obtained responses are found satisfactory, and total harmonic distortions of source currents are observed within an IEEE-519 standard limit.