Ningning Yang

Modeling and Characteristics Analysis for a Buck-Boost Converter in Pseudo-Continuous Conduction Mode Based on Fractional Calculus

In recent days, fractional calculus (FC) has been accepted as a novel modeling tool that can extend the descriptive power of the traditional calculus. Fractional-order descriptiveness can increase the flexibility and degrees of freedom of the model by means of fractional parameters. Based on the fact that real capacitors and inductors are “intrinsic” fractional order, fractional calculus is introduced into the modeling process to establish a fractional-order state-space averaging model of the Buck-Boost converter in pseudo-continuous conduction mode (PCCM). Orders of the model are considered as extra parameters, and these parameters have significant influences on the performance of the model. The inductor current, the inductor current ripple, the amplitude of the output voltage, and the transfer functions of the fractional-order model are all related to orders. The contrast simulation experiments are conducted to investigate the performance of integer-order and fractional-order Buck-Boost converters in PCCM. Results of numerical and circuit simulations demonstrate that the proposed theoretical analysis is effective; the fractional-order model of the Buck-Boost converter in PCCM has certain theoretical and practical significance for modeling and performance analysis of other electrical or electronic equipment.

A Novel Method Based on Self-Power Supply Control for Balancing Capacitor Static Voltage in MMC

The modular multilevel converter is one of the most attractive converter topologies for high-voltage dc transmission systems, but it needs at least 10 min during the system uncontrolled precharge stage to verify the stability and reliability of submodules (SMs), making the capacitor static voltage balancing a key issue. This paper proposes a novel method based on self-power supply control for balancing capacitor static voltage. Because of the influence of self-power supplies on capacitor voltages, the method can keep the capacitor static voltage balanced by controlling the input characteristic of SMs self-power supplies. The control signals of self-power supplies have a fixed frequency and duty ratio, and they can be determined based on capacitor voltage sorting results and self-power supply output support capacitor. Compared with previous works, this method has less computation, and it does not rely on IGBTs and additional complex circuits except for the self-power supplies. This can save on the software and hardware costs. The proposed method also leads to improved equalizing resistances and reduced active power losses of the SMs. Simulations and experimental studies were conducted, and the results confirm the effectiveness of the proposed method.

Fractional-Order Terminal Sliding-Mode Control for Buck DC/DC Converter

In recent years, the combination of fractional calculus (FC) and sliding-mode control (SMC) has been gaining more and more interests due to fusion characteristics of SMC and FC. This paper presents the fractional-order terminal sliding-mode control (FTSMC) which has a new fractional-order sliding surface and assures the finite time convergence of the output voltage error to the equilibrium point during the load changes. TSMC is a special case of FTSMC. Through mathematical analysis, the system can reach the sliding-mode surface in finite time. The theoretical considerations have been verified by numerical simulations. And a Buck DC/DC converter application is presented and compared to illustrate the effectiveness of the proposed method. It is shown that the novel fractional terminal sliding-mode control exhibits considerable improvement in terms of a faster output voltage response during load changes.

Adaptive Inverse Optimal Control of a Novel Fractional-Order Four-Wing Hyperchaotic System with Uncertain Parameter and Circuitry Implementation

An efficient approach of inverse optimal control and adaptive control is developed for global asymptotic stabilization of a novel fractional-order four-wing hyperchaotic system with uncertain parameter. Based on the inverse optimal control methodology and fractional-order stability theory, a control Lyapunov function (CLF) is constructed and an adaptive state feedback controller is designed to achieve inverse optimal control of a novel fractional-order hyperchaotic system with four-wing attractor. Then, an electronic oscillation circuit is designed to implement the dynamical behaviors of the fractional-order four-wing hyperchaotic system and verify the satisfactory performance of the controller. Comparing with other fractional-order chaos control methods which may have more than one nonlinear state feedback controller, the inverse optimal controller has the advantages of simple structure, high reliability, and less control effort that is required and can be implemented by electronic oscillation circuit.

Modeling and Analysis of a Fractional-Order Generalized Memristor-Based Chaotic System and Circuit Implementation

Memristor is a nonlinear “missing circuit element”, that can easily achieve chaotic oscillation. Memristor-based chaotic systems have received more and more attention. Research shows that fractional-order systems are more close to real systems. As an important parameter, the order can increase the flexibility and degree of freedom of the system. In this paper, a fractional-order generalized memristor, which consists of a diode bridge and a parallel circuit with an equivalent unit circuit and a linear resistance, is proposed. Frequency and electrical characteristics of the fractional-order memristor are analyzed. A chain structure circuit is used to implement the fractional-order unit circuit. Then replacing the conventional Chua’s diode by the fractional-order generalized memristor, a fractional-order memristor-based chaotic circuit is proposed. A large amount of research work has been done to investigate the influence of the order on the dynamical behaviors of the fractional-order memristor-based chaotic...

Analysis of a novel 4D fractional-order ferromagnetic chaotic system

In this paper, a novel four-dimensional(4D) fractional-order chaotic system is proposed deduced from the model of ferromagnetic resonance. The attractor is a three-dimensional (3D) torus like the Olympic nest in Beijing when the system is in stable state. Dynamic behaviors of the novel 4D ferromagnetic system are analyzed in detail, such as phase portrait, Poincare map, Lyapunov exponents and bifurcation diagram. Then the influence of the fractional-order on the dynamic behaviors of this system is analyzed. Numerical simulation results illustrate the feasibility of the novel system.

Dynamic analysis and fractional-order adaptive sliding mode control for a novel fractional-order ferroresonance system

Ferroresonance is a complex nonlinear electrotechnical phenomenon, which can result in thermal and electrical stresses on the electric power system equipments due to the over voltages and over currents it generates. The prediction or determination of ferroresonance depends mainly on the accuracy of the model used. Fractional-order models are more accurate than the integer-order models. In this paper, a fractional-order ferroresonance model is proposed. The influence of the order on the dynamic behaviors of this fractional-order system under different parameters n and F is investigated. Compared with the integral-order ferroresonance system, small change of the order not only affects the dynamic behavior of the system, but also significantly affects the harmonic components of the system. Then the fractional-order ferroresonance system is implemented by nonlinear circuit emulator. Finally, a fractional-order adaptive sliding mode control (FASMC) method is used to eliminate the abnormal operation state of power system. Since the introduction of the fractional-order sliding mode surface and the adaptive factor, the robustness and disturbance rejection of the controlled system are enhanced. Numerical simulation results demonstrate that the proposed FASMC controller works well for suppression of ferroresonance over voltage.

Projective synchronization and identification of two different Markovian jumping complex delayed networks with stochastic perturbations

In this paper, the projective synchronization and identification for two uncertain Markovian jumping complex delayed networks with nonidentical dimensions and stochastic perturbations is studied. On the strength of the Itôs formula and appropriate stochastic Lyapunov-Krasovskii functional, some sufficient conditions are obtained to ensure that the unknown parameters of the two Markovian jumping complex delayed networks with stochastic perturbations can be identified successfully. Finally, a numerical example is presented to illustrate the effectiveness and feasibility of our theory result.

Adaptive synchronization of a novel fractional-order hyperchaotic system with uncertain parameters

In this paper, the self-synchronization of a new constructed fractional-order hyperchaotic system with uncertain parameters is achieved by the method of adaptive control. Firstly, we proposed a novel fractional-order system which is derived from a integer-order hyperchaotic system. In order to verify the existence of the proposed fractional-order system, numerical simulation and circuitry experimental are carried out. Then to get the self-synchronization of this fractional-order system, adaptive controller is designed according to the stability theory of fractional-order system. By numerical simulation, the correctness and effectiveness of the proposed synchronization method is verified.

Simulation analysis on the propagation characteristics of electromagnetic wave in T-branch GIS based on FDTD

This paper investigates the propagation characteristics of partial discharge in Gas Insulated Substation (GIS). It is simulated based on the method of Finite Difference Time Domain (FDTD). Firstly the model for detecting PD signals in T-branch GIS is built according the real 220kV GIS experimental setup, and then we study the influence factors respectively. Also this paper makes experimental investigations on the propagation characteristics of PD induced by artificial insulation defect in real 220kV GIS. The simulation and experiment results show that the amplitude attenuation of electromagnetic wave has close contacts with pulse width and amplitude of the excitation source. This feature is used to determine the PD source type and evaluate the PD severity.