Type of Document Master's Thesis Author Li, Chi Author's Email Address email@example.com URN etd-08282015-155008 Title Design, Analysis and Experimental Evaluation of a Virtual Synchronous Machine Based Control Scheme for STATCOM Applications Degree Master of Science Department Electrical and Computer Engineering Advisory Committee
Advisor Name Title Rolando Burgos Committee Chair Lamine Mili Committee Co-Chair Dushan Boroyevich Committee Member Keywords
- virtual synchronous machine
Date of Defense 2015-08-20 Availability restricted AbstractBecause renewable energy sources are environment-friendly and inexhaustible, more and more renewable energy power plants have been integrated into power grids worldwide. To compensate for their inherent variability, STATCOMs are typically installed at the point of common coupling (PCC) to help their operation by regulating the PCC voltage. However under different contingencies, PCC voltage fluctuations in magnitude and frequency may impede the STATCOM from tracking the grid frequency correctly, hence worsening its overall compensation performance, and putting at risk the operation of the power plant. Further, the virtual synchronous machine (VSM) concept has recently been introduced to control grid-connected inverters emulating the behavior of rotating synchronous machines, in an effort to eliminate the shortcomings of conventional d-q frame phase-locked loops (PLL).
In this dissertation, the VSM concept is extended by developing a STATCOM controller with it, which then behaves like a fully-adjustable synchronous condenser, including the adjustment of its “virtual” inertia and impedance. An average model in two D-Q frames is proposed to analyze the inherent dynamics of the VSM-based STATCOM controller with insight into impacts from the virtual parameters and a design guideline is then formulated. The proposed controller is compared against existent d-q frame STATCOM control strategies, evincing how the VSM-based approach guarantees an improved voltage regulation performance at the PCC by adjusting the phase of its compensating current during frequency fluctuations, in both simulation and experiment.
Secondly, the dynamics of the VSM-based STATCOM controller in large signal sense is studied, especially its capability to ride through faults. Analysis is carried out with phasors to obtain a fundamental understanding at first and followed by state space equations to predict the transients analytically, which is validated by matching both simulation and experiment. The effects of two outer loops are also reviewed and some possible solutions are suggested and evaluated. Moreover, the relationship between the virtual inertia and the actual inertia is established and the dc capacitor sizing is discussed in a possibly more economical way. The start-up process of a VSM-based STATCOM is presented to implement a practical prototype as well.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access Li_Chi_T_2015.pdf 3.50 Mb 00:16:11 00:08:19 00:07:17 00:03:38 00:00:18indicates that a file or directory is accessible from the Virginia Tech campus network only.
If you have questions or technical problems, please Contact DLA.