scholarly journals Droop Method Development for Microgrids Control Considering Higher Order Sliding Mode Control Approach and Feeder Impedance Variation

2021 ◽  
Vol 11 (3) ◽  
pp. 967
Author(s):  
Abdonaser Saleh-Ahmadi ◽  
Mazda Moattari ◽  
Amir Gahedi ◽  
Edris Pouresmaeil
Keyword(s):  
Sliding Mode Control ◽  
Method Development ◽  
Reactive Power ◽  
Sliding Mode ◽  
Power Sharing ◽  
Control Approach ◽  
Mode Control ◽  
Impedance Variation ◽  
Parallel Mode ◽  
The Stability

Due to the growing power demands in microgrids (MGs), the necessity for parallel production achieved from distributed generations (DGs) to supply the load required by customers has been increased. Since the DGs have to procure the demand in parallel mode, they are faced with several technical and economic challenges, such as preventing DGs overloading and not losing network stability considering feeder impedance variation. This paper presents a method that upgrades the droop controller based on sliding mode approach, so that DGs are able to prepare a suitable reactive power sharing without error even in more complex MGs. In the proposed strategy, the third-order sliding mode controller significantly reduces the V-Q error and increases the accuracy in adjusting the voltage at the DG output terminals. Various case studies conducted out in this paper validate the truthfulness of the proposed method, considering the stability analysis using Lyapunov function. Finally, by comparing the control parameters of the proposed technique with existing methods, the superiority, simplicity and effectiveness of the 3rd order sliding mode control (SMC) method are determined.

scholarly journals Observer-Based Sliding Mode Control to Improve Stability of Three-Phase LCL-Filtered Grid-Connected VSIs

Energies ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1421 ◽  
Author(s):  
Min Huang ◽  
Han Li ◽  
Weimin Wu ◽  
Frede Blaabjerg
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Voltage Source ◽  
Voltage Source Inverters ◽  
Mode Control ◽  
Impedance Variation ◽  
Three Phase ◽  
Grid Impedance ◽  
The Stability ◽  
Fast Dynamic

Grid-connected voltage source inverters (VSIs) with LCL filters have been widely used for distributed generation systems (DGs). Various control methods have been studied to achieve good performance. Among them, sliding mode control has been applied to LCL-filtered grid-connected VSIs for its fast, dynamic response and strong robustness. However, LCL networks can easily cause instability problems under weak grid conditions such as grid impedance variation. At the same time, the stability design of sliding mode control applied for LCL-filtered grid-connected inverters are important, but they lack detailed parameters design in recent papers. In this paper, a design of observer-based sliding mode control to improve the stability of three-phase LCL-filtered grid-connected VSIs was proposed. The theoretical stability analysis was developed to consider the effect of the system discretization and grid impedance variations. Finally, a 3-kW, 110-V, 50-Hz experimental setup has been built to demonstrate the validation of the proposed method.

Design of adaptive optimal robust control for two-flexible-link manipulators in the presence of matched uncertainties

2020 ◽  
pp. 107754632093202
Author(s):  
Hamid Reza Shafei ◽  
Mohsen Bahrami ◽  
Heidar Ali Talebi
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Flexible Link ◽  
External Disturbances ◽  
Terminal Sliding Mode ◽  
Control Approach ◽  
Mode Control ◽  
Nonsingular Terminal Sliding Mode ◽  
Control Scheme ◽  
The Stability

This study uses a comprehensive control approach to deal with the trajectory tracking problem of a two-flexible-link manipulator subjected to model uncertainties. Because the control inputs of two-flexible-link manipulators are less than their state variables, the proposed controller should be able to tackle the stated challenge. Practically speaking, there is only a single control signal for each joint, which can be used to suppress link deflections and control joint trajectories. To achieve this objective, a novel optimal robust control scheme, with an updated gain under the adaptive law, has been developed in this work for the first time. In this regard, a nonsingular terminal sliding mode control approach is used as the robust controller and a control Lyapunov function is used as the optimal control law, to benefit from the advantages of both methods. To systematically deal with system uncertainties, an adaptive law is used to update the gain of nonsingular terminal sliding mode control. The advantage of this approach over the existing methods is that it not only can robustly and stably control an uncertain nonlinear system against external disturbances but also can optimally solve a quadratic cost function (e.g. minimization of control effort). The Lyapunov stability theory has been applied to verify the stability of the proposed approach. Moreover, to show the superiority of this method, the computer simulation results of the proposed method have been compared with those of an adaptive sliding mode control scheme. This comparison shows that the presented approach is capable of optimizing the control inputs while achieving the stability of the examined two-flexible-link manipulator in the presence of model uncertainties and external disturbances.

Robust tracking for hypersonic vehicles subjected to mismatched uncertainties via fixed-time sliding mode control

2021 ◽  
pp. 095441002199023
Author(s):  
Jianguo Guo ◽  
Shengjiang Yang ◽  
Zongyi Guo
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Fixed Time ◽  
Hypersonic Vehicles ◽  
Robust Tracking ◽  
Control Approach ◽  
Mode Control ◽  
Mismatched Uncertainties ◽  
The Stability ◽  
Mismatched Disturbances

This article investigates the robust tracking issue for the longitudinal dynamics of hypersonic vehicles subjected to mismatched uncertainties, and a novel sliding mode control approach is proposed to achieve the fixed-time convergence of tracking errors and satisfactory robustness against mismatched uncertainties. Establishing the control-oriented hypersonic vehicle model as velocity and altitude subsystems with mismatched uncertainties, the article introduces the nonlinear finite-time disturbance observer technique to estimate the uncertainties precisely. With the estimated uncertainties from the observer, the fixed-time sliding mode control is presented to track the velocity and altitude references. Consequently, the effect of the mismatched disturbances can be eliminated and the tracking performance can be improved. The stability of the closed-loop system is also analyzed. Numerical simulation results demonstrate the validity and superiority of the proposed control.

scholarly journals Observer-based adaptive neural network backstepping sliding mode control for switched fractional order uncertain nonlinear systems with unmeasured states

2021 ◽  
pp. 002029402110211
Author(s):  
Tao Chen ◽  
Damin Cao ◽  
Jiaxin Yuan ◽  
Hui Yang
Keyword(s):  
Neural Network ◽  
Nonlinear Systems ◽  
Sliding Mode Control ◽  
Fractional Order ◽  
Sliding Mode ◽  
Tracking Error ◽  
Adaptive Neural Network ◽  
Dynamic Surface ◽  
Mode Control ◽  
The Stability

This paper proposes an observer-based adaptive neural network backstepping sliding mode controller to ensure the stability of switched fractional order strict-feedback nonlinear systems in the presence of arbitrary switchings and unmeasured states. To avoid “explosion of complexity” and obtain fractional derivatives for virtual control functions continuously, the fractional order dynamic surface control (DSC) technology is introduced into the controller. An observer is used for states estimation of the fractional order systems. The sliding mode control technology is introduced to enhance robustness. The unknown nonlinear functions and uncertain disturbances are approximated by the radial basis function neural networks (RBFNNs). The stability of system is ensured by the constructed Lyapunov functions. The fractional adaptive laws are proposed to update uncertain parameters. The proposed controller can ensure convergence of the tracking error and all the states remain bounded in the closed-loop systems. Lastly, the feasibility of the proposed control method is proved by giving two examples.

scholarly journals Sliding Mode Control and Geometrization Conjecture in Seismic Response

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 353
Author(s):  
Ligia Munteanu ◽  
Dan Dumitriu ◽  
Cornel Brisan ◽  
Mircea Bara ◽  
Veturia Chiroiu ◽  
...  
Keyword(s):  
Sliding Mode Control ◽  
Ricci Flow ◽  
Lyapunov Functions ◽  
Seismic Waves ◽  
Sliding Mode ◽  
Flow Process ◽  
Mode Control ◽  
Finite Period ◽  
The Stability ◽  
Story Building

The purpose of this paper is to study the sliding mode control as a Ricci flow process in the context of a three-story building structure subjected to seismic waves. The stability conditions result from two Lyapunov functions, the first associated with slipping in a finite period of time and the second with convergence of trajectories to the desired state. Simulation results show that the Ricci flow control leads to minimization of the displacements of the floors.

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