This paper presents a novel adaptive neuro-fuzzy inference system based on interval Gaussian type-2 fuzzy sets in the antecedent part and Gaussian type-1 fuzzy sets as coefficients of linear combination of input variables in the consequent part. The capability of the proposed ANFIS2 for function approximation and dynamical system identification is remarkable. The structure of ANFIS2 is very similar to ANFIS but in ANFIS2, a layer is added for purpose to type reduction. An adaptive learning rate based back propagation with convergence guaranteed is used for parameter learning. Finally, the proposed ANFIS2 is used to control of a flexible link robot arm. Simulation results shows the proposed ANFIS2 with Gaussian type-1 fuzzy set as coefficients of linear combination of input variables in the consequent part has good performance and high accuracy but more training time. تفاصيل المقالة

Using Tracking Differentiators in Designing Nonlinear Disturbance Observers for Uncertain SystemsNaser Kazemzadeh, Saeed BarghandanAbstractIn the present paper, a practical designing method has been proposed for a novel class of NDOs based on TD. Such NDOs can nearly estimate all uncertain disturbances (specifically disturbances without prediction information). Regarding the outstanding performance of TD filter not requiring a precise dynamic model, the proposed NDO can estimate external disturbance and not modeled dynamics. The results showed the superiority of the proposed method in estimating disturbance and improvement of control quality.Keywords: non-linear systems, uncertain disturbances, non-linear disturbance observer (NDO), tracking differentiator تفاصيل المقالة

Due to the variable and non-uniform nature of wind speed, using the variable speed wind power plants equipped with induction generators has advantages over the fixed speed wind power plants; however, it also contains some disadvantages such as consuming a large amount of reactive current in the power grid and causes voltage drop and instability. The use of static synchronous compensator or STATCOM is one of the key methods to improve the power profile in wind farms. STATCOM can control the voltage dynamics, improve transient stability, eliminate power fluctuations in the transmission network, and control the real and reactive power. Regarding to the fluctuations in electricity generated in wind farms, the presented case study proposed methods to improve the active power and compensate reactive power using the STATCOM in wind systems by modeling in Simulink environment of MATLAB software. According to the simulation results, by applying the STATCOM to the studied system, changes in active power and reactive power generated from the wind farm are significantly reduced. In addition, studies in terms of total harmonic distortion (THD) show that by employing STATCOM, the amount of output voltage distortion is vastly decreased. تفاصيل المقالة

Nowadays, among the renewable energy resources, wind energy is more economically viable than other new sources. To achieve the maximum power at different wind speeds, the turbine speed must be variable over a wide range. Electricity generation from wind is performed by different models of wind turbines with different generators. Due to the capabilities and advantages such as relatively high power density, low noise, high efficiency, high reliability and low maintenance costs, wind turbines equipped with permanent magnet synchronous generator (PMSG) are in increasing use. This paper presents a method for modeling and controlling the stability of PMSG-equipped power systems using static synchronous compensator (STATCOM). STATCOM is a static synchronous generator that is installed in parallel with the power grid and is used as a reactive power compensator which plays an effective role in voltage stability. The main goal of this study is to develop a reliable control strategy for wind farms and STATCOM to investigate the effect of reactive power losses under constant and sub-fault conditions. Furthermore, to increase the attenuation of the synchronous generator of single-machine system with infinite bus, STATCOM with PID controller is connected to the studied system to rise the dynamic stability of the PMSG based wind turbine. تفاصيل المقالة

Due to the variable and non-uniform nature of wind speed, using the variable speed wind power plants equipped with induction generators has advantages over the fixed speed wind power plants; however, it also contains some disadvantages such as consuming a large amount of reactive current in the power grid and causes voltage drop and instability. The use of static synchronous compensator or STATCOM is one of the key methods to improve the power profile in wind farms. STATCOM can control the voltage dynamics, improve transient stability, eliminate power fluctuations in the transmission network, and control the real and reactive power. Regarding to the fluctuations in electricity generated in wind farms, the presented case study proposed methods to improve the active power and compensate reactive power using the STATCOM in wind systems by modeling in Simulink environment of MATLAB software. According to the simulation results, by applying the STATCOM to the studied system, changes in active power and reactive power generated from the wind farm are significantly reduced. In addition, studies in terms of total harmonic distortion (THD) show that by employing STATCOM, the amount of output voltage distortion is vastly decreased. تفاصيل المقالة

Regarding the daily increasing development of process and chemical industries and the requirement to improve energy consumption and increasing the output, advanced process control strategies are utilized effectively. Model predictive control as a successful developed process control has been proposed to deal with problems having constraints and multivariable systems. The successful administration of this strategy requires proper adjustment of its’ parameters. In this research, three reservoir system has been modeled as a laboratory plant and predictive control algorithm for first order system with delay has been designed in the form of an unlimited case. The delayed first order model has been achieved though the implementation of a white noise signal into the plant to recognize the system. Then parameters were adjusted using an analytic method. Results of simulations showed that model predictive control has represented an optimal performance through proper adjustment of the parameters. تفاصيل المقالة

One of the most time-consuming parts of video encoding is motion estimation. Motion estimation is an important part of video encoding that improves the amount and accuracy of compression by exploiting the temporal similarity between successive frames. This action is the main cause of maximum compression in the video, which imposes the minimum quality loss on the video. In order to be able to compensate the movement, it is necessary to first find the value of the movement direction, which is called movement estimation.By doing motion estimation, instead of sending repeated information at consecutive times, the difference between consecutive frames is encoded and sent in different ways. Generally, a motion estimator in video encoding includes fractional pixel motion estimation (FME) and integer pixel motion estimation (IME). The FME method provides better performance with the cost of computational complexity and estimation time on the encryption process. تفاصيل المقالة

Sometimes conventional feedback controllers may not perform well online because of the variation in process dynamics due to nonlinear actuators, changes in environmental conditions and variation in the character of the disturbances. To overcome the above problem, this paper deals with the designing of a controller for a second order system with Model Reference Adaptive Control (MRAC) scheme using the MIT rule for adaptive mechanism. In this rule, a cost function is defined as a function of error between the outputs of the plant and the reference model, and controller parameters are adjusted in such a way so that this cost function is minimized. The designed controller gives satisfactory results, but is very sensitive to the changes in the amplitude of reference signal. It follows from the simulation work carried out in this paper that adaptive system becomes unstable if the value of adaptation gain or the amplitude of reference signal is sufficiently large. This paper also deals with the use of MIT rule along with the normalized algorithm to handle the variations in the reference signal, and this adaptation law is referred as modified MIT rule. The performances of the proposed control algorithms are evaluated and shown by means of simulation on MATLAB and Simulink تفاصيل المقالة

Operator failures in controlled systems can reduce their operation, cause instability and even cause dangerous casualties and accidents. Flaw causes structural changes and parametric uncertainties in the control system, which requires a new modeling for the control system as well as new control methods. The design of the control is applied to the dynamic model in the presence of a defect in the radar, ellerron and motor operators. The intended damage for these operators is considered to be "locked in place", that is, after the defect, the control levels remain uncertain and constant. In this paper, we examine several different control methods for controlling the operation of operators in the presence of uncertainty. تفاصيل المقالة