A fixed-time fractional-order sliding mode control strategy for power quality enhancement of PMSG wind turbine

Author(s):  
Sunhua Huang ◽  
Jie Wang ◽  
Chen Huang ◽  
Lidan Zhou ◽  
Linyun Xiong ◽  
...  
2021 ◽  
Vol 14 (1) ◽  
pp. 484-495
Author(s):  
Rania Moutchou ◽  
◽  
Ahmed Abbou ◽  
Salah Rhaili ◽  
◽  
...  

This paper presents a modelling study and focuses on an advanced higher order slip mode control strategy (Super Twisting Algorithm) for a variable speed wind turbine based on a permanent magnet synchronous generator to capture the maximum possible wind power from the turbine while simultaneously reducing the effect of mechanical stress, powered by a voltage inverter and controlled by vector PWM technique. This paper presents first and second order sliding mode control schemes. On the other hand, a challenging matter of pure SMC of order one can be summed up in the produced chattering phenomenon. In this work, this issue has been mitigated by implementing a new control. The proposed control, characterized by a precision in the case of a continuation of a significant reduction of the interference phenomenon, successfully addresses the problems of essential non-linearity of wind turbine systems. This type of control strategy presents more advanced performances such as behaviour without chattering (no additional mechanical stress), excellent convergence time, robustness in relation to external disturbances (faults in the network) and to non-modelled dynamics (generator and turbine) which have been widely used in power system applications by first order sliding mode control. In particular, second-order sliding regime control algorithms will be applied to the PMSG to ensure excellent dynamic performance. The suggested control is compared to the proportional-integral controller and sliding mode control of order one. The results of simulations under turbulent wind speed and parameter variations show the efficiency, robustness and significantly improved performance of the proposed control approach to distinguish and track quickly (about 10ms depending on the shading pattern) and at the same time saving the main priorities of the sliding mode of order one by reducing the existing chatter. The systems performances were tested and compared using Matlab/Simulink Software.


2020 ◽  
Vol 26 (17-18) ◽  
pp. 1425-1434 ◽  
Author(s):  
Sunhua Huang ◽  
Jie Wang

In this study, a fractional-order sliding mode controller is effectively proposed to stabilize a nonlinear power system in a fixed time. State trajectories of a nonlinear power system show nonlinear behaviors on the angle and frequency of the generator, phase angle, and magnitude of the load voltage, which would seriously affect the safe and stable operation of the power grid. Therefore, fractional calculus is applied to design a fractional-order sliding mode controller which can effectively suppress the inherent chattering phenomenon in sliding mode control to make the nonlinear power system converge to the equilibrium point in a fixed time based on the fixed-time stability theory. Compared with the finite-time control method, the convergence time of the proposed fixed-time fractional-order sliding mode controller is not dependent on the initial conditions and can be exactly evaluated, thus overcoming the shortcomings of the finite-time control method. Finally, superior performances of the fractional-order sliding mode controller are effectively verified by comparing with the existing finite-time control methods and integral order sliding mode control through numerical simulations.


Author(s):  
Clara Ionescu ◽  
Cristina Muresan

AbstractIn this paper, a sliding mode control strategy is discussed for a class of nonlinear mechanical sub-systems with varying trajectory dynamics. The proposed class of sub-systems are represented in this simulation example by a two link robot actuator/manipulator. The fractional order is introduced in the setpoint definition as to represent changes in the desired trajectory of this sub-system. Furthermore, the same order is used to adapt the control law to the new dynamics. Uncertainties are introduced in the model used for the control law, hence robustness is intrinsic.


2017 ◽  
Vol 14 (2) ◽  
pp. 172988141769429 ◽  
Author(s):  
Dong Zhang ◽  
Lin Cao ◽  
Shuo Tang

This article presents a new fractional-order sliding mode control (FOSMC) strategy based on a linear-quadratic regulator (LQR) for a class of uncertain nonlinear systems. First, input/output feedback linearization is used to linearize the nonlinear system and decouple tracking error dynamics. Second, LQR is designed to ensure that the tracking error dynamics converges to the equilibrium point as soon as possible. Based on LQR, a novel fractional-order sliding surface is introduced. Subsequently, the FOSMC is designed to reject system uncertainties and reduce the magnitude of control chattering. Then, the global stability of the closed-loop control system is analytically proved using Lyapunov stability theory. Finally, a typical single-input single-output system and a typical multi-input multi-output system are simulated to illustrate the effectiveness and advantages of the proposed control strategy. The results of the simulation indicate that the proposed control strategy exhibits excellent performance and robustness with system uncertainties. Compared to conventional integer-order sliding mode control, the high-frequency chattering of the control input is drastically depressed.


Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Peng Gao ◽  
Xiaodong Lv ◽  
Huimin Ouyang ◽  
Lei Mei ◽  
Guangming Zhang

This study proposes a novel model-free intelligent proportional-integral supertwisting nonlinear fractional-order sliding mode control (MF-iPI-ST-NLFOSMC) strategy for permanent magnet synchronous motor (PMSM) speed regulation system. First of all, a model independent intelligent proportional-integral (iPI) control strategy is adopted for the motor speed regulation system. Next, a novel model-free supertwisting nonlinear fractional-order sliding mode control (ST-NLFOSMC) strategy is constructed based on the ultralocal model of PMSM. Meanwhile, a linear extended state observer (LESO) is used to estimate the unknown terms of the ultralocal model. Then, this study presents the novel hybrid MF-iPI-ST-NLFOSMC strategy which integrates the model-free ST-NLFOSMC strategy, the model-free iPI control strategy, and the LESO. Moreover, the stability of the proposed hybrid MF-iPI-ST-NLFOSMC strategy is proved by the Lyapunov stability theorem and fractional-order theory. Finally, the simulations and comparison results verify that the hybrid MF-iPI-ST-NLFOSMC strategy proposed in this paper has better performance than the other model-free controllers in terms of the static characteristic, dynamic characteristic, and robustness.


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