scholarly journals Robust Fuzzy-Second Order Sliding Mode based Direct Power Control for Voltage Source Converter

Author(s):  
D. Kairous ◽  
B. Belmadani
Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3886 ◽  
Author(s):  
Han ◽  
Ma

In a wind turbine system, a doubly-fed induction generator (DFIG), with nonlinear and high-dimensional dynamics, is generally subjected to unbalanced grid voltage and unknown uncertainty. This paper proposes a novel adaptive-gain second-order sliding mode direct power control (AGSOSM-DPC) strategy for a wind-turbine-driven DFIG, valid for both balanced and unbalanced grid voltage. The AGSOSM-DPC control scheme is presented in detail to restrain rotor voltage chattering and deal with the scenario of unknown uncertainty upper bound. Stator current harmonics and electromagnetic torque ripples can be simultaneously restrained without phase-locked loop (PLL) and phase sequence decomposition using new active power expression. Adaptive control gains are deduced based on the Lyapunov stability method. Comparative simulations under three DPC schemes are executed on a 2-MW DFIG under both balanced and unbalanced grid voltage. The proposed strategy achieved active and reactive power regulation under a two-phase stationary reference frame for both balanced and unbalanced grid voltage. An uncertainty upper bound is not needed in advance, and the sliding mode control chattering is greatly restrained. The simulation results verify the effectiveness, robustness, and superiority of the AGSOSM-DPC strategy.


Mathematics ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 2012
Author(s):  
Mohammed Mazen Alhato ◽  
Soufiene Bouallègue ◽  
Hegazy Rezk

A second-order sliding mode (SOSM)-based direct power control (DPC) of a doubly-fed induction generator (DFIG) is introduced in this research paper. Firstly, the DFIG output powers are regulated with the developed SOSM controller-based DPC scheme. The Super Twisting Algorithm (STA) has been used to reduce the chattering phenomenon. The proposed strategy is a combination of the Lyapunov theory and metaheuristics algorithms, which has been considered to identify the optimal gains of the STA-SOSM controllers. The Lyapunov function method is employed to define the stability regions of the controller parameters. On the other hand, the metaheuristics algorithms are mainly employed to select the fine controllers’ parameters from the predefined ranges. A Thermal Exchange Optimization (TEO) method is used to compute the optimal gain parameters. To prove the superiority of the proposed TEO, its obtained results have been compared with those obtained by other algorithms, including particle swarm optimization, genetic algorithm, water cycle algorithm, grasshopper optimization algorithm and harmony search algorithm. Moreover, the results of the introduced TEO-based SOSM controller have been also compared with the Proportional-Integral (PI)-based vector control and the conventional sliding mode control-based DPC. Moreover, an empirical comparison is carried out to investigate the indication of every metaheuristics method by employing Friedman’s rank and Bonferroni tests. The main findings indicate the effectiveness of STA-SOSM control for system stability and power quality improvement. The ripples in the active and reactive powers are minimized and the harmonics’ distortions of stator and rotor currents are improved. Besides, the STA-SOSM controller shows a superior performance of control in terms of chattering phenomenon elimination.


Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2692 ◽  
Author(s):  
Shiyang Hu ◽  
Guorong Liu ◽  
Nan Jin ◽  
Leilei Guo

This paper proposes a constant-frequency model predictive direct power control (CF-MPDPC) method for a fault-tolerant bidirectional voltage-source converter (BVSC). The method can enhance the reliability and fault-tolerant operation capability of BVSCs in the condition of bridge-arm fault. Through the analysis of a fault-tolerant three-phase four-switch (TPFS) structure and the voltage vectors in the αβ stationary frame, the predictive power model and DC-link midpoint voltage offset suppression are established. According to model-predictive theory, fault-tolerant TPFS, and multivector control, the CF-MPDPC method for fault-tolerant BVSC is presented. The method realizes direct power control based on three output vectors with constant frequency, which can track the optimal vector more accurately and reduce current harmonics. Furthermore, the balanced control of DC-link capacitor voltages is also achieved by adding the term of DC-link midpoint voltage offset into the cost function. The balanced capacitor voltages protect the converter against the second faults caused by over-voltage operation of electrolytic capacitor. The simulation and experimental results prove that the fault-tolerant BVSC controlled by proposed method can maintain the continuous operation when the switching devices have fault. Low current harmonic content and stable output power exhibit good reliability and dynamic performance of the proposed CF-MPDPC for a fault-tolerant BVSC with a phase fault.


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