Sensor-less maximum power extraction control of a hydrostatic tidal turbine based on adaptive extreme learning machine

In this paper, a hydrostatic tidal turbine (HTT) is designed and modelled, which uses more reliable hydrostatic transmission to replace existing fixed ratio gearbox transmission. The HTT dynamic model is derived by integrating governing equations of all the components of the hydraulic machine. A nonlinear observer is proposed to predict the turbine torque and tidal speeds in real time based on extreme learning machine (ELM). A sensor-less double integral sliding mode controller is then designed for the HTT to achieve the maximum power extraction in the presence of large parametric uncertainties and nonlinearities. Simscape design experiments are conducted to verify the proposed design, model and control system, which show that the proposed control system can efficiently achieve the maximum power extraction and has much better performance than conventional control. Unlike the existing works on ELM, the weights and biases in the ELM are updated online continuously. Furthermore, the overall stability of the controlled HTT system including the ELM is proved and the selection criteria for ELM learning rates is derived. The proposed sensor-less control system has prominent advantages in robustness and accuracy, and is also easy to implement in practice

Power Quality Enhancement in Electricity Grids with Wind Energy Using Multicell Converters and Energy Storage

In recent years, the wind power industry is experiencing a rapid growth and more wind farms with larger size wind turbines are being connected to the power system. While this contributes to the overall security of electricity supply, large-scale deployment of wind energy into the grid also presents many technical challenges. Most of these challenges are one way or another, related to the variability and intermittent nature of wind and affect the power quality of the distribution grid. Power quality relates to factors that cause variations in the voltage level and frequency as well as distortion in the voltage and current waveforms due to wind variability which produces both harmonics and inter-harmonics. The main motivation behind work is to propose a new topology of the static AC/DC/AC multicell converter to improve the power quality in grid-connected wind energy conversion systems. Serial switching cells have the ability to achieve a high power with lower-size components and improve the voltage waveforms at the input and output of the converter by increasing the number of cells. Furthermore, a battery energy storage system is included and a power management strategy is designed to ensure the continuity of power supply and consequently the autonomy of the proposed system. The simulation results are presented for a 149.2 kW wind turbine induction generator system and the results obtained demonstrate the reduced harmonics, improved transient response, and reference tracking of the voltage output of the wind energy conversion system.Peer reviewedFinal Accepted Versio

DFIG Driven Wind Turbine Grid Fault-Tolerance Using High-Order Sliding Mode Control

International audienceThis research note deals with grid fault-tolerance of a doubly-fed induction generator-based wind turbine using high-order sliding mode control. Indeed, it is proposed to assess the main and attractive features of high-order sliding modes which are robustness against external disturbances (e.g. grid) and chattering-free behavior (no extra mechanical stress on the drive train). Simulations using the NREL FAST code on a 1.5-MW wind turbine are carried-out to evaluate ride-through performances of high-order sliding mode control

Wind Turbine Tribology

Wind power is of increasing interest in society due to its prospects as an environmentally friendly source of renewable energy. The use of wind turbines to extract electrical energy from wind can be dated back to the late-1800s, with the 12 kW windmill generator by Charles Brush, as well as the mid-1900s, with the 1250 kW Smith-Putnam wind turbine. Developments in the wind industry were encouraged by the oil crisis in 1973

Fuzzy second order sliding mode control of a unified power flow controller

Purpose. This paper presents an advanced control scheme based on fuzzy logic and second order sliding mode of a unified power flow controller. This controller offers advantages in terms of static and dynamic operation of the power system such as the control law is synthesized using three types of controllers: proportional integral, and sliding mode controller and Fuzzy logic second order sliding mode controller. Their respective performances are compared in terms of reference tracking, sensitivity to perturbations and robustness. We have to study the problem of controlling power in electric system by UPFC. The simulation results show the effectiveness of the proposed method especiallyin chattering-free behavior, response to sudden load variations and robustness. All the simulations for the above work have been carried out using MATLAB / Simulink. Various simulations have given very satisfactory results and we have successfully improved the real and reactive power flows on a transmission lineas well as to regulate voltage at the bus where it is connected, the studies and illustrate the effectiveness and capability of UPFC in improving power.В настоящей статье представлена усовершенствованная схема управления, основанная на нечеткой логике и режиме скольжения второго порядка унифицированного контроллера потока мощности. Данный контроллер обладает преимуществами с точки зрения статической и динамической работы энергосистемы, например, закон управления синтезируется с использованием трех типов контроллеров: пропорционально-интегрального, контроллера скользящего режима и контроллера скользящего режима нечеткой логики второго порядка. Их соответствующие характеристики сравниваются с точки зрения отслеживания эталонов, чувствительности к возмущениям и надежности. Необходимо изучить проблему управления мощностью в энергосистеме с помощью унифицированного контроллера потока мощности (UPFC). Результаты моделирования показывают эффективность предложенного метода, особенно в отношении отсутствия вибрации, реакции на внезапные изменения нагрузки и устойчивости. Все расчеты для вышеуказанной работы были выполнены с использованием MATLAB/Simulink. Различные расчетные исследования дали весьма удовлетворительные результаты, и мы успешно улучшили потоки реальной и реактивной мощности на линии электропередачи, а также регулирование напряжения на шине, к которой она подключена, что позволяет изучить и проиллюстрировать эффективность и возможности UPFC для увеличения мощности

Super-twisting Sliding Mode Control of a Doubly-fed Induction Generator Based on the SVM Strategy

This paper presents direct power control (DPC) strategies using the super-twisting sliding mode control (STSMC) applied to active and reactive power control of a doubly-fed induction generator (DFIG) supplied by a space vector modulation inverter for wind turbine system. Then, a control STSMC-DPC and SVM strategies are applied. The active and reactive powers that are generated by the DFIG will be decoupled by the orientation of the stator flux and controlled by super-twisting sliding mode control. Its simulated performance is then compared with conventional sliding mode control. The test of robustness of the controllers against machine parameters uncertainty will be tackled, and the simulations will be presented. Simulation results of the proposed controller (SMC-DPC) and (STSMC-DPC) scheme are compared for various step changes in the active and reactive power. This approach super-twisting sliding mode control is validated using the Matlab/Simulink software and the results of the simulation can prove the excellent performance of this control in terms of improving the quality of the energy supplied to the electricity grid

Synthesis of SMC algorithms applied to wind generator

The use of the classical (SMC) applied to control of stator’s powers of DFIG, gives the problem of chattering, therefore to avoid this phenomenon a robust algorithm (STSMC) is applied. This paper presents a comparison of conventional SMC with the proposed strategy of STSMC algorithm. The results are obtained using MATLAB and demonstrate stability and robustness of this algorithm

Improved Super Twisting Based High Order Direct Power Sliding Mode Control of a Connected DFIG Variable Speed Wind Turbine

This work presents the theoretical and practical comparison of linear and nonlinear control laws for the direct power control of a grid-connected double fed induction generator (DFIG), based wind energy conversion system (WECS) under different operating modes. We will show the improvement brought by the super twisting based high order sliding mode control to mitigate the chattering phenomenon, due to the high switching frequency. It will also avoid the hyperlink of the controller settings to the system’s mathematical model and will reduce the sensibility to external disturbances. The overall structure of the proposed control requires the use of the DFIG simplified model with field-oriented control (FOC). This last allows an instantaneous decoupled control of the DFIG stator active and reactive power by acting on dq rotor currents (Iqr , Idr ) respectively. In the preliminary tests, a comparative study is conducted to verify the superior performance of the proposed WECS control scheme during various operating modes including the maximum power point tracking MPPT mode. The study reveals the effectiveness of each implemented control law with its advantages and drawbacks

Measurement based method for online characterization of generator dynamic behaviour in systems with renewable generation

This paper introduces a hybrid-methodology for online identification and clustering of generator oscillatory behavior, based on measured responses. The dominant modes in generator measured responses are initially identified using a mode identification technique and then introduced, in the next step, as input into a clustering algorithm. Critical groups of generators that exhibit poorly or negatively damped oscillations are identified, in order to enable corrective control actions and stabilize the system. The uncertainties associated with operation of modern power systems, including Renewable Energy Sources (RES) are investigated, with emphasis on the impact of the dynamic behavior of power electronic interfaced RES