Robustness Improvement of Superconducting Magnetic Energy Storage System in Microgrids Using an Energy Shaping Passivity-Based Control Strategy

• Published in: Energies (Basel) 2017-05, Vol.10 (5), p.671
• Main Authors: Hou, Rui, Song, Huihui, Nguyen, Thai-Thanh, Qu, Yanbin, Kim, Hak-Man
• Format: Article
• Language: English
• Subjects: Control systems; Controllers; Damping; Design analysis; Design engineering; Design improvements; Direct current; Eddy currents; Electric power grids; Electric utilities; Energy consumption; Energy management; energy shaping passivity (ESP)-based control; Energy storage; Harmonics; Magnetic energy storage; microgrid (MG); Nonlinearity; Passivity; renewable power generation; Simulation; Strategy; superconducting magnetic energy storage (SMES); Superconductivity; Systems analysis
• ISSN: 1996-1073; 1996-1073
• DOI: 10.3390/en10050671

Superconducting magnetic energy storage (SMES) systems, in which the proportional-integral (PI) method is usually used to control the SMESs, have been used in microgrids for improving the control performance. However, the robustness of PI-based SMES controllers may be unsatisfactory due to the high nonlinearity and coupling of the SMES system. In this study, the energy shaping passivity (ESP)-based control strategy, which is a novel nonlinear control based on the methodology of interconnection and damping assignment (IDA), is proposed for robustness improvement of SMES systems. A step-by-step design of the ESP-based method considering the robustness of SMES systems is presented. A comparative analysis of the performance between ESP-based and PI control strategies is shown. Simulation and experimental results prove that the ESP-based strategy achieves the stronger robustness toward the system parameter uncertainties than the conventional PI control. Besides, the use of ESP-based control method can reduce the eddy current losses of a SMES system due to the significant reduction of 2nd and 3rd harmonics of superconducting coil DC current.