Assessment of reactive power contribution of photovoltaic energy systems on voltage profile and stability of distribution systems

• Published in: International journal of electrical power & energy systems 2014-10, Vol.61, p.665-672
• Main Authors: Aly, Mohamed M., Abdel-Akher, Mamdouh, Ziadi, Zakaria, Senjyu, Tomonobu
• Format: Article
• Language: English
• Subjects: Applied sciences; Cloud effects; Continuation power-flow; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Exact sciences and technology; Miscellaneous; Operation. Load control. Reliability; Photoelectric conversion; Photovoltaic energy systems; Power electronics, power supplies; Power networks and lines; Reactive power; Regulation; Voltage stability
• ISSN: 0142-0615; 1879-3517
• DOI: 10.1016/j.ijepes.2014.02.040

•PV inverters are modeled and implemented to study voltage profile of 24h series.•Continuation power-flow method is developed to assess the voltage stability.•Cloud effects on voltage stability are simulated and studied for different inverters. This paper studies the impact of large-scale photovoltaic (PV) generation, up to 50% penetration level, on distribution system voltage regulation and voltage stability. The system voltage profiles are computed using power-flow calculations with load variation of a 24-h time scale. The steady-state voltage stability is examined at different times of the day using a developed continuation power-flow method with demand as continuation parameter and up to the maximum loading conditions. The load-flow analysis, implemented for both voltage regulation and voltage stability analysis, is performed by using the forward/backward sweep method. The secant predictor technique is developed for predicting the node voltages which are then corrected using the load flow solver. Three models of the PV interface inverter are implemented in this study with full set of data representing environmental conditions. The voltage profiles are regulated using the PV interface inverters, where the available inverter capacity is utilized for regulating the system node voltages. The most possible scenarios of system voltage collapse are investigated at different times of the study period. The developed methods and models are used to assess the performance of a 33-bus radial distribution feeder which operates with a high level of PV penetration. The results show that the PV interface inverters operate for reactive power support in distribution system resulting in improved voltage profile, secure power systems operation, and increasing the lifetime of the online tap changing transformers due to minimizing the total number of switching operations.