Said Doubabi

Induction motor speed drive improvement using fuzzy IP-self-tuning controller. A real time implementation

An IP-self-tuning controller tuned by a fuzzy adjustor, is proposed to improve induction machine speed control. The interest of such controller is the possibility to adjust only one gain, instead of two gains for the case of the PI-self-tuning controllers commonly used in the literature. This paper presents simulation and experimental results. These latter were obtained by practical implementation on a DSPace 1104 board of three different speed controllers (the classical IP, the fuzzy-like-PI and the IP-self-tuning), for a 1.5KW induction machine. The paper presents different tests used to compare the performances of the proposed controller to the two others in terms of computation time, tracking performances and disturbances rejection.

Modeling and regulation of a micro hydroelectric power plant

Hydropower is emerging as a major contributor to the world energy requirement. Itpsilas inexhaustible, clean and has many other benefits as it doesnpsilat encounter the problems of population displacement and environmental problems. However, it requires control systems to keep the frequency values constant. In this paper we develop a mathematical model for a micro hydroelectric power plant (MHPP). We validate this model by analysing a MHPP prototypepsilas performances. The prototype is installed in our laboratory. We use the downstream regulation which ensures good frequency regulation results. The used controller is the dasiaPIpsila one. The practical results obtained are similar for those in simulation.

IM Direct Torque Control with no flux distortion and no static torque error

The purpose of this paper is to improve DTC control strategy performances. In fact, we propose controlling both stator flux components (real and imaginary) through two hysteresis controllers. Thus, a new switching table which is independent from sector determination, and does not introduce zero voltage vectors is established; with much reduced size when compared to Takahashis one. The proposed strategy has allowed cutting off with flux and current harmonics related to distortion caused by sector exchanges. Also, we provide theoretical evidence about the existence of static torque error in classical DTC, and propose a simple PI-type controller to cancel it. The proposed strategy is validated by simulation and practically on a DSPace 1104 board, for a 1.5 (kW) induction motor and various torque references.

Design of a robust digital controller for congestion control in Internet

Abstract This paper is concerned with the design of a robust AQM control scheme for congestion control in Internet. The design of efficient control schemes is challenging since the TCP congestion window model presents both time-varying time delay, appearing in the state and the control signal, and model uncertainties, due to variations of network characteristic parameters. Hence, our paper begins firstly by giving sufficient conditions for stability and stabilizability for the class of systems whose dynamic is similar to the TCP congestion window one, in term of LMI. After, the general results obtained are applied to congestion control, resulting in a new AQM which is implemented in NS2 and compared to other ones in the literature, as PI and REM. The simulations emphasized the effectiveness of our AQM and its improvements with respect to the other control schemes.

Design of an AQM for routers supporting TCP flows by means of Lyapunov theory

In this paper, an active queue management (AQM) for TCP flows is designed by means of Lyapunov theory. To this end, we choose a non conservative Lyapunov candidate function which allows knowing how the marking/droping process should be done to achieve stability. This design leads to an AQM based on rate mismatch which insure responsiveness to the variation of the networks characteristics, and is suitable even in case of non or full cooperation of the network users. Furthermore, the proposed AQM that we refer as LYAP was implemented under NS2 and compared to REM. The simulation results emphasized the effectiveness the LYAP.

A robust controller for the TCP congestion window

In this paper a robust active queue management (AQM) for TCP flows is designed. We synthesized a robust controller by using the Hinfin control based on weight method. This was done by defining two weights W1(s) and W2(s); the first taking account of the desired performances and the second insuring the robustness of the controller to the model uncertainties. We also compared our controller with other ones proposed in the literature.

Design and simulation of fuzzy controller and supervisor for a micro-hydro power plant

Micro-hydro power plants (MHPP) are usually built on mountains to provide electricity for rural areas. Most of MHPP are isolated from national electrical grid network, which requires a good control system to keep the MHPP frequency and voltage outputs constant in spite of changing user loads. This paper focuses on the development of a control system that consists of a fuzzy controller and a fuzzy supervisor. The fuzzy controller is used to ensure good frequency regulation and to limit the waste of the available water on the reservoir. The proposed fuzzy supervisor manages the electrical production between departures that form the mini-grid. It is able either to disconnect or connect the less preferred departures, according to the level of the available water. The proposed control system can be considered to be a mean of power quality control, to improve the frequency fluctuations caused by random power fluctuations on the load side. Simulation results show overall the effectiveness and feasibility of the proposed fuzzy control system.

Comparative study based on thermal efficiency of solar air heaters

This article investigates various aspects of solar air heaters applied to drying process. Also, the paper presents a comparison between different types of solar collectors in terms of thermal efficiency and outlet temperature based on experimental results achieved by different authors. New improved technologies that increase the efficiency of these devices are discussed. Analysis and tables obtained in this document can be a helpful tool for a designing engineer to construct economical and efficient solar air heaters.

Modeling a three-phase micro hydropower plant prototype using Takagi-Sugeno fuzzy approach

This paper presents a Takagi-Sugeno (TS) fuzzy model of a three-phase micro hydropower plant (MHPP) prototype. It represents the system as an interpolation between local models. Each local model is linear system validated around an operating point. The Three-phase MHPP behavior varies with load variations and water flows. These matters create difficulties to have an exact model close to real system. This paper proposes a multi-model approach for modeling the overall behavior of the three-phase MHPP based on the identification of a simple approximation of first and second order systems around several operating points (different water flows and load variations). The results show that the approximation results of second order system have high accordance with the real system responses. This approximation offers more opportunities to synthesize suitable robust controllers for MHPP based on digital calculators, especially when the proposed approach is used in closed loop. Besides, the paper also presents a new load-frequency structure for three-phase MHPP. This structure is controlled by a simple Proportional Integral (PI) controller. The developed TS fuzzy models were experimentally validated taking into consideration various working conditions.

TS fuzzy output control for a boost converter in PV systems

This paper presents fuzzy output tracking control of switching photovoltaic (PV) DC-DC converters. The proposed control ensures good performances and overall large-signal stability of the system over the whole operating space. To do this, we present a model of PV system and a state space model for DC-DC boost converter. Then, we introduce an added integral state of the output tracking error. The resulting augmented system is converted into a Takagi sugeno fuzzy model (TSFM). The Parallel distributed compensation (PDC) concept is employed to design the state-feedback based control law whereby the control gains are fined using the linear quadratic regulator (LQR) technique. Finally, the design procedures are applied to a dynamics model of typical PV power control system using a DC-DC boost converter to illustrate the effectiveness of the proposed control techniques.