A State-Space Dynamic Model for Photovoltaic Systems With Full Ancillary Services Support

• Published in: IEEE transactions on sustainable energy Vol. 10; no. 3; pp. 1399 - 1409
• Main Authors: Batzelis, Efstratios I., Anagnostou, Georgios, Cole, Ian R., Betts, Thomas R., Pal, Bikash C.
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.07.2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Ancillary services; asymmetrical faults; Computational modeling; Computer applications; Computer simulation; Conduction; discontinuous conduction mode (DCM); dynamic model; Dynamic models; Economic models; Electric converters; frequency response; Inductors; Integrated circuit modeling; Inverters; Irradiance; Lambert W function; Mathematical model; Phase locked loops; photovoltaic (PV) system; Photovoltaic cells; Photovoltaics; Power system dynamics; Solar cells; state-space model; System dynamics; two-stage system; Voltage converters (DC to DC); Voltage sags
• ISSN: 1949-3029; 1949-3037
• DOI: 10.1109/TSTE.2018.2880082

Large-scale photovoltaic (PV) integration to the network necessitates accurate modeling of PV system dynamics under solar irradiance changes and disturbances in the power system. Most of the available PV dynamic models in the literature are scope-specific, neglecting some control functions and employing simplifications. In this paper, a complete dynamic model for two-stage PV systems is presented, given in entirely state-space form and explicit equations that takes into account all power circuit dynamics and modern control functions. This is a holistic approach that considers a full range of ancillary services required by modern grid codes, supports both balanced and unbalanced grid operation, and accounts for the discontinuous conduction mode of the dc/dc converter of the system. The proposed dynamic model is evaluated and compared to other approaches based on the literature, against scenarios of irradiance variation, voltage sags, and frequency distortion. Simulation results in MATLAB/Simulink indicate high accuracy at low computational cost and complexity.