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Modeling and Mechanism Investigation of Inertia and Damping Issues for Grid-Tied PV Generation Systems with Droop Control

1
School of Electrical and Control Engineering, Shaanxi University of Science & Technology, Xi’an 710021, China
2
School of Electrical and Information Engineering, Hunan University of Technology, Zhuzhou 412008, China
3
Department of Electrical Engineering, Hong Kong Polytechnic University, Hong Kong 999077, China
4
School of Automation, Nanjing Institute of Technology, Nanjing 211167, China
*
Author to whom correspondence should be addressed.
Energies 2019, 12(10), 1985; https://doi.org/10.3390/en12101985
Received: 23 April 2019 / Revised: 17 May 2019 / Accepted: 20 May 2019 / Published: 23 May 2019
(This article belongs to the Section Solar Energy and Photovoltaic Systems)
Inertia effect and damping capacity, which are the basic characteristics of traditional power systems, are critical to grid frequency stability. However, the inertia and damping characteristics of grid-tied photovoltaic generation systems (GPVGS), which may affect the frequency stability of the grid with high proportional GPVGS, are not yet clear. Therefore, this paper takes the GPVGS based on droop control as the research object. Focusing on the DC voltage control (DVC) timescale dynamics, the mathematical model of the GPVGS is firstly established. Secondly, the electrical torque analysis method is used to analyze the influence law of inertia, damping and synchronization characteristics from the physical mechanism perspective. The research finds that the equivalent inertia, damping and synchronization coefficient of the system are determined by the control parameters, structural parameters and steady-state operating point parameters. Changing the control parameters is the simplest and most flexible way to influence the inertia, damping and synchronization ability of the system. The system inertia is influenced by the DC voltage outer loop proportional coefficient Kp and enhanced with the increase of Kp. The damping characteristic of the system is affected by the droop coefficient Dp and weakened with the increase of Dp. The synchronization effect is only controlled by DC voltage outer loop integral coefficient Ki and enhanced with the increase of Ki. In addition, the system dynamic is also affected by the structural parameters such as line impedance X, DC bus capacitance C, and steady-state operating point parameters such as the AC or DC bus voltage level of the system and steady-state operating power (power angle). Finally, the correctness of the above analysis are verified by the simulation and experimental results. View Full-Text
Keywords: grid-tied photovoltaic generation system; deloading maximum power point tracking; DC voltage control timescale; electrical torque analysis method; inertia and damping characteristics grid-tied photovoltaic generation system; deloading maximum power point tracking; DC voltage control timescale; electrical torque analysis method; inertia and damping characteristics
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Wu, Y.; Zhang, D.; Xiong, L.; Wang, S.; Xu, Z.; Zhang, Y. Modeling and Mechanism Investigation of Inertia and Damping Issues for Grid-Tied PV Generation Systems with Droop Control. Energies 2019, 12, 1985.

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