Search

This paper presents a fast terminal sliding-mode tracking control for a class of uncertain nonlinear systems with unknown parameters and system states combined with time-varying disturbances. Fast terminal sliding-mode finite-time tracking systems based on differential evolution algorithms incorporate an integral chain differentiator (ICD) to feedback systems for the estimation of the unknown system states. The differential evolution optimization algorithm using ICD is also applied to a tracking controller, which provides unknown parametric estimation in the limitation of unknown system states for trajectory tracking. The ICD in the tracking systems strengthens the tracking controller robustness for the disturbances by filtering noises. As a powerful finite-time control effort, the fast terminal sliding-mode tracking control guarantees that all tracking errors rapidly converge to the origin. The effectiveness of the proposed approach is verified via simulations, and the results exhibit high-precision output tracking performance in uncertain nonlinear systems. [ABSTRACT FROM AUTHOR]

This paper presents a new system for reactive power compensation and suppression of negative-sequence current for power quality improvement in electrical railways and the feeding three-phase utility grid, based on YNvd-connected balance transformer. Different from the conventional railway static power conditioner based compensation systems, this system integrates multiplex back-to-back converters (MBTBC) into phase-β side flexible taps through a cascade connection instead of into phase-β side feeder via a coupling transformer, thus the installation space and initial costs are reduced significantly. In addition, a new power distribution strategy with simple implementation is adopted in this paper, by which the compensation capacity of MBTBC can be decreased by 25%, compared with the commonly used full compensation scheme. As the first part of this topic, this paper focuses on the theoretical analysis, including the system topology, basic and partial compensation principles and its implementation method. While, the controller design on converter-level, stability analysis, and simulation and experimental verification are the main tasks of the second part of this topic. [ABSTRACT FROM PUBLISHER]

This part mainly focuses on the implementation and verification of the reactive power compensation and negative-sequence current suppression system with YNvd-connected balance transformer, by means of simulation and experiment. The system model is presented, and a current control method, which explores the dissipation characteristic of the proposed system under two-phase rotating frame, is analyzed. Then, a stability analysis of this control is made, considering the deviations of system parameters and the time delay caused by the low-pass filter. Besides, dc-link overall control and balance control are investigated, and the self-balance ability of multiple dc links is briefly discussed. Both the simulation and experimental results verify the effectiveness of the proposed system topology, compensation strategy, and control method. [ABSTRACT FROM AUTHOR]