Disturbance observer based robust voltage control of photovoltaic generator interfaced by current mode buck converter

• Published in: Energy conversion and management 2020-04, Vol.209, p.112622, Article 112622
• Main Authors: Sitbon, M., Aharon, I., Averbukh, M., Baimel, D., Sassonker (Elkayam), M.
• Format: Article
• Language: English
• Subjects: Batteries; Buck converter; Buck converters; Control methods; Control tasks; Controllers; Disturbance; Disturbance observer; Disturbance observers; Energy storage; Environmental conditions; Microgrid; Photovoltaic generator; Photovoltaics; Proportional integral; Robust control
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2020.112622

•Disturbance observer based robust voltage control of photovoltaic generator interfaced by buck converter is proposed.•Exploiting disturbance observer as a counteraction to the nonlinear loop regulation variables.•The method robustify voltage control loop with consideration to the possibility of unstable Pole. In this paper, a new control method for photovoltaic generator is presented. The novel method is implemented on photovoltaic generator charging a battery storage system thru buck converter. The controller tasks are re-shaping the buck plant converter, and cancel its right half-pole while keeping tight reference tracking and disturbance rejection. Moreover, the integrated system of generator-converter-load possesses nonlinear behavior due to the varying environmental conditions and the boundaries of photovoltaic generator versus battery state of charge, as revealed from an analysis of small-signal equations for possible unstable condition. It was shown that system constrains consequence in a complicated control task where standard controller of an inverse plant is insufficient to stabilize the system. Then a proportional integral controller is implemented. However, it is shown that varying closed-loop performance from over-damped to under-damped, depending on the operating point. Eventually utilizing a robust disturbance observer controller reveals that closed-loop performance remains nearly nominal throughout the entire operation range.