Virtual Damping Control Design of Three-Phase Grid-Tied PV Inverters for Passivity Enhancement

Zhiqing Yang, Chirag Shah, Tianxiao Chen, Jakob Teichrib, Rik W. De Doncker, IEEE Transactions on Power Electronics, 03 November 2020, doi: 10.1109/TPEL.2020.3035417

Abstract

This paper investigates passivity properties influenced by different control loops and operating points in the dq frame, which facilitates the stability assessment in the frequency domain. Based on this, a virtual damping control method is proposed to improve the stability by enhancing the system passivity. By implementing a damping transfer function in the d and q axis individually, non-passive regions can be accordingly reduced over a specific frequency range. Asymmetrical designs can be considered in the d and q axis according to corresponding passivity properties, which is impossible to be realized through symmetric physical filter components. The design procedure is elaborated based on a 2 MW inverter system, which is based on a combined graphical and analytical approach. Verifications are conducted based on a 1 kW prototype including both simulations and experimental results. The method applies to all types of grid-tied inverters with multiple control loops..

DOI: IEEE