Title :
Smooth mode transition of A DC bus voltage controlled PV inverter using a novel phase locked loop method
Author :
Das, Partha Pratim ; Chattopadhyay, Souvik
Author_Institution :
Dept. of Electr. Eng., Indian Inst. of Technol. Kharagpur, Kharagpur, India
Abstract :
This paper describes a control algorithm for smooth transition from standalone (SA) to grid connected (GC) mode of a PV connected two stage inverter. High voltage DC bus is obtained by using a frontend boost converter. The DC bus voltage is kept regulated during all the modes of operation. A new phase reference generation method is also described which does not require any lookup table. The PLL synchronization method is also described and verified with experiments. The system runs in voltage control mode during standalone mode of operation keeping output voltage constant irrespective of change in load. If grid becomes available, it performs a smooth transition from stand alone to grid-connected mode. If grid fault occurs grid voltage falls bellow allowable level. In this situation system does a mode transition and goes to SA mode. In GC mode system runs in current control where current reference comes from maximum power point tracking algorithm. The strategy has been verified with experiments, and results are presented in this paper.
Keywords :
electric current control; invertors; phase locked loops; photovoltaic power systems; power grids; synchronisation; voltage control; DC bus voltage controlled PV inverter; PLL synchronization method; PV connected two stage inverter; SA mode; current control; frontend boost converter; grid connected mode; grid fault; grid voltage; maximum power point tracking algorithm; phase locked loop method; phase reference generation method; smooth mode transition; standalone mode; voltage control mode; Frequency control; Inverters; Mathematical model; Maximum power point trackers; Phase locked loops; Synchronization; Voltage control; Grid connected mode; MPPT; PLL; Standalone mode;
Conference_Titel :
Applied Power Electronics Conference and Exposition (APEC), 2015 IEEE
Conference_Location :
Charlotte, NC
DOI :
10.1109/APEC.2015.7104644