A comparative study of methods for estimating virtual flux at the point of common coupling in grid connected voltage source converters with LCL filter
Location: Milwaukee, USA
Publication date: 2016-09-18
Published in: IEEE Energy Conversion Congress and Exposition 2016, Milwaukee (USA) - ECCE 2016
ref. DOI: 10.1109/ECCE.2016.7854660

Local members

Alvaro Luna

PhD. Senior Researcher.

Joan Rocabert

PhD. Senior Researcher

Jose Ignacio Candela

PhD. Senior Researcher. Project Responsible

Nurul Fazlin Roslan

Junior Researcher

External members

Jon Are Suul



Grid connected Voltage Source Converters (VSCs) with LCL filters usually have voltage measurements at the filter capacitors, while it can be important to control the active or reactive power injection at the grid-side of the LCL filter, for instance at a Point of Common Coupling (PCC). Synchronization to the PCC voltage can be obtained by Virtual Flux (VF) estimation, which can also allow for voltage sensor-less operation of VSCs. This paper is presenting a comparative evaluation of methods for estimating the VF at the PCC, considering a VSC connected to the grid through an LCL filter with a Proportional Resonant (PR) controller as the inner current control loop. The VF estimation is achieved by using frequency adaptive dual SOGI-QSGs (DSOGI-VF). The Frequency Locked Loop (FLL) is used in order to keep the positive and negative sequence (PNS) VF estimation inherently frequency adaptive. Three different methods are considered for obtaining the capacitor current needed for estimating the VF at the grid side of the LCL filter which are based on fully estimation by using the voltage sensor-less method, by estimating the capacitor current from the measured voltage or by using additional capacitor current sensors. The results have been compared and validated by simulation studies.