This paper proposes a novel solution to the problems that exist in the conventional hill climb searching (HCS) maximum power point tracking (MPPT) algorithm for the wind energy conversion system. The presented solution not only solves the tracking speed versus control efficiency tradeoff problem of HCS but also makes sure that the changing wind conditions do not lead HCS in the wrong direction. It intelligently adapts the variable step size to keep up with the rapid changes in the wind and seizes the perturbation at the maxima to yield 100% control efficiency. For this purpose, a novel peak detection capability has been devised which, in contrast with conventional peak detection, can work robustly under changing wind conditions. The proposed MPPT performs self-tuning to cope with the nonconstant efficiencies of the generator-converter subsystems-a phenomenon quite rarely discussed in research papers so far. In addition, a smart speed-sensorless scheme has been developed to avoid the use of mechanical sensors. The experimental results confirm that the proposed algorithm is remarkably faster and more efficient than the conventional HCS.

A Novel Algorithm for Fast and Efficient Speed-Sensorless Maximum Power Point Tracking in Wind Energy Conversion Systems

Wind power is the most reliable and developed renewable energy source over past decades. With the rapid penetration of the wind generators in the power system grid, it is very essential to utilize the maximum available power from the wind and to operate the wind turbine (WT) at its maximal energy conversion output. For this, the wind energy conversion system (WECS) has to track or operate at the maximum power point (MPP). A decent variety of publication report on various maximum power point tracking (MPPT) algorithms for a WECS. However, making a choice on an exact MPPT algorithm for a particular case require sufficient proficiency because each algorithm has its own merits and demerits. For this reason, an appropriate review of those algorithms is essential. However, only a few attempts have been made in this concern. In this paper, different available MPPT algorithms are described for extracting maximum power which are classified according to the power measurement i.e. direct or indirect power controller. Merits, demerits and comprehensive comparison of the different MPPT algorithms also highlighted in the terms of complexity, wind speed requirement, prior training, speed responses, etc. and also the ability to acquire the maximal energy output. This paper serves as a proper reference for future MPPT users in selecting appropriate MPPT algorithm for their requirement.

A review of conventional and advanced MPPT algorithms for wind energy systems

We review the objectives and techniques used in the control of horizontal axis wind turbines at the individual turbine level, where controls are applied to the turbine blade pitch and generator. The turbine system is modeled as a flexible structure operating in the presence of turbulent wind disturbances. Some overview of the various stages of turbine operation and control strategies used to maximize energy capture in below rated wind speeds is given, but emphasis is on control to alleviate loads when the turbine is operating at maximum power. After reviewing basic turbine control objectives, we provide an overview of the common basic linear control approaches and then describe more advanced control architectures and why they may provide significant advantages.

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Control of wind turbines: Past, present, and future

This paper proposes a maximum power point tracking (MPPT) algorithm for small-scale wind energy conversion systems. The proposed algorithm uses the dc current as the perturbing variable. The algorithm detects sudden wind speed changes indirectly through the dc-link voltage slope. The voltage slope is also used to enhance the tracking speed of the algorithm and to prevent the generator from stalling under rapid wind speed slowdown conditions. The proposed method uses two modes of operation: A perturb and observe (P&O) mode with adaptive step size under slow wind speed fluctuation conditions, and a prediction mode employed under fast wind speed change conditions. The dc-link capacitor voltage slope reflects the acceleration information of the generator, which is then used to predict the next step size and direction of the current command. The proposed algorithm shows enhanced stability and fast tracking capability under both high and low rate of change wind speed conditions and is verified using a 1.5 kW prototype hardware setup.

Design and Analysis of an MPPT Technique for Small-Scale Wind Energy Conversion Systems

A review on wind turbine control and its associated methods

According to the aerodynamical characteristic of the wind turbine, a maximum power point tracking (MPPT) is necessary to get high efficiency for wind power conversion, which means that the rotating speed of wind turbine should be adjusted in the real time to capture maximum wind power. Because of the fast variation of wind speed and the heavy inertia of generator, the MPPT control of wind generation is much challengeable. A new MPPT control scheme has been developed for permanent magnetic (PM) generator driven by a three-phase inverter to generate 350 V direct current power to the DC bus line. The main differences between the method used in the proposed MPPT system and other techniques used in the past are as follows: (1) the tracking step is variable according to the change of wind speed; (2) in order to avoid the dead time effect of the inverter the MPPT control is synchronized to the rotating speed of the generator; (3) a low pass filter is used at the output of the MPPT controller to decrease the fluctuation of the rotating speed reference. The resulting system has high-efficiency, lower-cost and fast, stable tracking speed. The experimental results show that it can track as fast as 0.2Hz variation of wind speed and increases the output wind power as much as 48%. As a result, the efficiency of the generation has been improved evidently.

A new maximum power point tracking control scheme for wind generation

This paper discusses the nonlinear control problem for variable-speed wind energy conversion system Due to the stochastic operating conditions and the inevitable uncertainties inherent in the system, linear control method comes at the price of poor system performance and low reliability So, it first develops a detailed model of variable-speed wind energy conversion system, which incorporated a distributed generation and then applies the robust sliding mode incorporating fuzzy tuning schemes designing controller for robust performance of optimizing the generator converter system efficiency Analysis and experiment show that the method is able achieve smooth and satisfactory rotor speed tracking In addition, a comparison study have been carried out between the proposed method and the tradition variable speed operation control method that adjust the pitch angle only It is found that the proposed method could diminish fatigue of mechanism

Robust sliding mode control of variable-speed wind power system

http://www.nt.ntnu.no/users/skoge/prost/proceedings/ifac2002/data/content/02568/2568.pdf

Yang zhongqing

Papers

A new maximum power point tracking control scheme for wind generation

Robust sliding mode control of variable-speed wind power system

Nonlinear control of variable-speed wind energy conversion system