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Due to wind turbine is in class of complex nonlinear system so the precise model of this plant is not accessible, therefore it can be categorized as an uncertain model. So, controlling of this system is a demanding topic. Many of schemes which presented for controlling of wind turbines investigate these systems in a good weather condition. However, many turbines work in severe weather condition. In this study, wind turbine is suggested in cold weather, and in ice on turbine blades which they are considered as uncertainties in the model. A robust controller is designed for the wind turbine, to control the pitch angle.

Today, with the movement of power systems towards competition and breaking the monopoly, the importance of ancillary services like reactive power and voltage control has increased. One of the most important services is power reactive service. Independent System Operator (ISO)has to provide reactive power in deregulated environments which are considered one of the six ancillary services of power system which should be provided by the ISO to improve system security. ISO is responsible to provide reactive power in deregulated environments. Purpose of this paper is to present a method for pricing reactive power. In this method, reactive power pricing is performed based on Financial Transmission Rights (FTRs). The novelty of this study is that it has offered a new method for pricing reactive power based on FTR. Reactive power pricing methods presented so far have not considered congestion costs of the transmission system but this method considers congestions costs also through considering FTR. In this paper, results of this method are evaluated on a standard IEEE-30 bus test system and compared with current pricing method used for pricing reactive power in Iran.

Due to their complicated dynamics coupled with kinematics and non-holonomic underactuated behavior, spherical robots cannot unveil their full maneuverability when linear controllers are applied. Because of that, position and trajectory tracking of spherical robots have been the main challenges recently tackled in the literature. In this paper, two controllers are introduced to provide the effective path following of a 2-DOF spherical robot. A sliding mode controller (SMC) and a fuzzy sliding mode controller (FSMC) are designed and compared. The Lyapunov stability theorem is employed to analyze the stability of the controller and the tracking error. The simulation results indicate that the spherical robot controlled by the proposed methods is capable of moving to a desired point from any given initial point with minimum tracking error.

DC microgrid (MG) is an important structure of future electrical power systems, with many advantages in off grid and application for grid connected operation. It is considered for its stability, safety, reliability, and optimum efficiency. Power produced with renewable energy sources or changes in different stages or for reliability issue is controlled by power electronic advices like converters and inverters. Although some researches could invent new methods for dealing with challenges in microgrid systems, some aspects are still under research. Meanwhile, grounding architectures impact on power electronic converters needed to investigate more. This research presents the grounding method acts as a high impedance grounding in normal condition to avoid DC stray currents flow, and for fault transients acts as solid grounding. Then ground fault current is limited through a limiter resistor, to the permissible value, resulted in protecting power electronic interfaces.

In this paper a controller is designed for voltage source converters (VSC) using Nyquist array. Real systems existing in industry are nonlinear systems with multiple inputs and multiple outputs (MIMO). Such systems are always affected by different undesired factors like noise and distortion. But multivariable control design for linear systems is based on theories which are robust against noise, disturbances and uncertainties. DC and AC part of VSC are affected with disturbances which should be controlled. Thus, a Nyquist array is applied to VSC to study design and analysis of multivariable control based on the presented theories. The proposed controller is illustrated by simulation.

This paper deals with a reliable control technique to control wind generator. The wind generator’s structure is categorized as a complicated nonlinear system. The accurate scheme of this system cannot be obtained, so the model has high uncertainty and nonlinearity. So, controlling of this system becomes more attractive for scholars; however, many of approaches were given for regulating of wind generators explore these kind of systems in a normal weather situations. In practice several generators operate in an unpleasant weather condition. For having a realistic controller, is assumed that there are uncertainties in the model, for this purpose wind generator is recommended in the cold climate, also with the ice on generators blades. A promising controller is modeled, in order to control the pitch angel of wind. Finally, simulation outcomes will be provided to confirm the presented control approach.

Due to their complicated dynamics and underactuated nature, spherical robots require advanced control methods to reveal all their manoeuvrability features. This paper considers the path tracking control problem of a spherical robot equipped with a 2-DOF pendulum. The pendulum has two input torques that allow it to take angles about the robot’s transverse and longitudinal axes. Due to mechanical technicalities, it is assumed that these angles are immeasurable. First, a neural network observer is designed to estimate the pendulum angles. Then a modified sliding mode controller is proposed for the robot’s tracking control in the presence of uncertainties. Next, the Lyapunov theorem is utilized to analyse the overall stability of the proposed scheme, including the convergence of the observer estimation and the trajectory tracking errors. Finally, simulation results are provided to indicate the effectiveness of the proposed method in comparison with the other available control approaches.