Current Issue : July - September Volume : 2016 Issue Number : 3 Articles : 4 Articles
The gains of phase-locked-loop (PLL) have significant impacts on the power transfer limits for the voltage source converter (VSC)\nconnected to weak AC system. Therefore, in this paper, an improved PLL control, respectively, with alternative damping factors for\nrectifier and inverter is proposed. First, it is proved that the impedance angle of AC system has a great impact on the small-signal\nstability of the VSC system.With the same variation tendency ofTh�´evenin equivalent resistance, the limits of power transmission\nare changing in opposite trends for rectifier and inverter. Second, the improved PLL with alternative damping factors is proposed\nbased on the participation factor analysis. Third, the optimal damping factors of the improved PLL control for rectifier and inverter\nare calculated. Simulations and calculations validated the following three conclusions: (1) in rectifying operation, the equivalent\nsystem resistance has a negative impact on the stability of the system and this is not the case for inverting operation; (2) adding\nthe alternative damping factors to PLL control shows similar results compared with changing the impedance angle of AC system;\n(3) the proposed optimal damping factors of PLL can effectively extend the power transfer limits under both rectifier and inverter\nmodes....
This paper proposes a robust adaptive output feedback control strategy which can automatically regulate control gain for\nchaos synchronization. Chaotic systems with input nonlinearities, delayed nonlinear coupling, and external disturbance can\nachieve synchronization by applying this strategy. Utilizing Lyapunov method and LMI technique, the conditions ensuring chaos\nsynchronization are obtained. Finally, simulations are given to show the effectiveness of our control strategy....
This paper deals with the problems of the robust stochastic stability and stabilization for a class of uncertain discrete-time stochastic\nsystems with interval time-varying delays and nonlinear disturbances. By utilizing a new Lyapunov-Krasovskii functional and\nsome well-known inequalities, some new delay-dependent criteria are developed to guarantee the robust stochastic stability of\na class of uncertain discrete-time stochastic systems in terms of the linear matrix inequality (LMI). Then based on the state\nfeedback controller, the delay-dependent sufficient conditions of robust stochastic stabilization for a class of uncertain discrete-time\nstochastic systems with interval time-varying delays are established. The controller gain is designed to ensure the robust stochastic\nstability of the closed-loop system. Finally, illustrative examples are given to demonstrate the effectiveness of the proposed method....
Mainly due to the hostile environment in wastewater plants (WWTPs), the reliability of sensors with respect to important qualities\nis often poor. In this work, we present the design of a semiadaptive fault diagnosis method based on the variational Bayesian\nmixture factor analysis (VBMFA) to support process monitoring.The proposed method is capable of capturing strong nonlinearity\nand the significant dynamic feature of WWTPs that seriously limit the application of conventional multivariate statistical methods\nfor fault diagnosis implementation.The performance of proposed method is validated through a simulation study of a wastewater\nplant. Results have demonstrated that the proposed strategy can significantly improve the ability of fault diagnosis under fault-free\nscenario, accurately detect the abrupt change and drift fault, and even localize the root cause of corresponding fault properly....
Loading....