Abstract
Quasi-Z-source inverters (qZSIs) are becoming a powerful power conversion technology in photovoltaic (PV) power systems because they allow energy power conversion in a single stage operation. However, they can cause system resonances and reduce system damping, which may lead to instabilities. These stability problems are well known in grid-connected voltage source converter systems but not in quasi-Z-source inverter (qZSI)-based PV power systems. This paper contributes with Matlab/Simulink and PSCAD/EMTDC models of qZSI-based PV power systems to analyze transient interactions and stability problems. These models consider all power circuits and control blocks of qZSI-based PV power systems and can be used in sensitivity studies on the influence of system parameters on stability. PV power system stability is assessed from the proposed models. The causes of instabilities are analyzed from numerical simulations and possible solutions are proposed.
Highlights
Penetration of wind and solar PV energies in grids has been rapidly growing in the last few years [1,2,3,4]
Unlike most published works, which mainly focus on quasi-Z-source inverters (qZSIs) dynamic behavior, improvement of the DC side of qZSI-based PV power systems and impact of the AC impedance network on qZSI-based PV power system stability, this paper presents a broader study about qZSI-based PV power system stability that provides the following contributions to understand the qZSI-based PV power system dynamics:
Solutions to improve qZSI-based PV power system stability. These contributions can be a useful tool and a guide on qZSI-based PV power system stability works for designers, engineers and researchers
Summary
Penetration of wind and solar PV energies in grids has been rapidly growing in the last few years [1,2,3,4]. Several works characterize dynamic behavior of PV power systems with a two-stage boost DC/DC converter and a DC/AC VSI, and investigate stability [4,18,19] They conclude that solar irradiance and temperature lead to variations in a PV power system operating point, affecting system stability [18,19] and that control parameters have an influence on it too [4]. A broad and worthy study of pole-zero location and impact of parameters on the dynamics of several impedance-source-network-based power converters (including qZSIs)] considering the wide operating ranges of different sources is developed in [9]. These contributions can be a useful tool and a guide on qZSI-based PV power system stability works for designers, engineers and researchers
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