scholarly journals LMI-Based State Feedback Control Structure for Resolving Grid Connectivity Issues in DFIG-Based WT Systems

Eng ◽  
2021 ◽  
Vol 2 (4) ◽  
pp. 562-591
Author(s):  
Muhammad Arif Sharafat Ali
Keyword(s):  
Feedback Control ◽  
Power Plants ◽  
State Feedback ◽  
Control Structure ◽  
Rapid Onset ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Grid Voltage ◽  
Grid Connection ◽  
Doubly Fed

Pertaining to the connectivity issues in wind power plants with grids, this study introduces an efficient mechanism based on a state feedback control structure to establish a fast and stable grid connection for a wind-driven doubly-fed induction generator (DFIG). Owing to a direct link through stator windings, a DFIG is significantly vulnerable to grid disturbances and experiences sizable inrush currents when connected to the power grid. The proposed control structure is designed based on a linear matrix inequality stabilization criterion, which is framed using a suitable Lyapunov candidate function. The control objective is to ensure that the stator voltage can exponentially converge to the grid voltage, accounting for balanced and unbalanced grid conditions. This is achieved by generating appropriate rotor voltage references for rotor-side converter control. This study also explores the capability of the proposed control structure to enhance the system’s robustness to external disturbances and uncertain parametric variations. Simulations confirmed the effectiveness and suitability of the developed structure in mitigating the adverse effects of the rapid onset of the grid voltage at the stator terminals of the DFIG under various grid conditions; the proposed structure could thus establish a reliable connection with negligible effects on the DFIG and the grid.

scholarly journals Robust Mixed H2/H∞ State Feedback Controller Development for Uncertain Automobile Suspensions with Input Delay

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 359
Author(s):  
Nan Liu ◽  
Hui Pang ◽  
Rui Yao
Keyword(s):  
Feedback Control ◽  
State Feedback ◽  
Actuator Saturation ◽  
Output Feedback Control ◽  
Active Suspension ◽  
Feedback Controller ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Control Approach ◽  
State Feedback Controller

In order to achieve better dynamics performances of a class of automobile active suspensions with the model uncertainties and input delays, this paper proposes a generalized robust linear H2/H∞ state feedback control approach. First, the mathematical model of a half-automobile active suspension is established. In this model, the H∞ norm of body acceleration is determined as the performance index of the designed controller, and the hard constraints of suspension dynamic deflection, tire dynamic load and actuator saturation are selected as the generalized H2 performance output index of the designed controller to satisfy the suspension safety requirements. Second, a generalized H2/H∞ guaranteed cost state-feedback controller is developed in terms of Lyapunov stability theory. In addition, the Cone Complementarity Linearization (CCL) algorithm is employed to convert the generalized H2/H∞ output-feedback control problem into a finite convex optimization problem (COP) in a linear matrix inequality framework. Finally, a numerical simulation case of this half-automobile active suspension is presented to illustrate the effectiveness of the proposed controller in frequency-domain and time-domain.

State Feedback Control for Fractional Differential Systems with Riemann-Liouville Derivative

2012 ◽  
Vol 562-564 ◽  
pp. 2053-2056
Author(s):  
Yuan Fang
Keyword(s):  
Feedback Control ◽  
State Feedback ◽  
Sufficient Conditions ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Feedback Controllers ◽  
Differential Systems ◽  
Fractional Differential Systems ◽  
Liouville Derivative ◽  
Fractional Differential

This paper studies state feedback control for fractional differential systems with Riemann-Lιiouville derivative, which matrix A not satisfying the condition ιarg(λ(A))ι>α/2 . Based on the state feedback controllers’ designer, and Linear Matrix Inequality (LMI) apαproach, sufficient conditions for the systems with fraction order α (0<α<1) and α (1≤α<2) obtained respectively.

scholarly journals Frequency-Adaptive Current Controller Design Based on LQR State Feedback Control for a Grid-Connected Inverter under Distorted Grid

Energies ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2674 ◽  
Author(s):  
Rizka Bimarta ◽  
Thuy Vi Tran ◽  
Kyeong-Hwa Kim
Keyword(s):  
Feedback Control ◽  
Discrete Time ◽  
State Feedback ◽  
State Feedback Control ◽  
Frequency Variation ◽  
Grid Voltage ◽  
Frequency Information ◽  
Full State ◽  
Full State Feedback ◽  
Grid Connected Inverter

This paper proposes a frequency-adaptive current control design for a grid-connected inverter with an inductive–capacitive–inductive (LCL) filter to overcome the issues relating to both the harmonic distortion and frequency variation in the grid voltage. The current control scheme consists of full-state feedback control to stabilize the system and integral control terms to track the reference in the presence of disturbance and uncertainty. In addition, the current controller is augmented with resonant control terms to mitigate the harmonic component. The control scheme is implemented in the synchronous reference frame (SRF) to effectively compensate two harmonic orders at the same time by using only one resonant term. Moreover, to tackle the frequency variation issue in grid voltage, the frequency information which is extracted from the phase-locked loop (PLL) block is processed by a moving average filter (MAF) for the purpose of eliminating the frequency fluctuation caused by the harmonically distorted grid voltage. The filtered frequency information is employed to synthesize the resonant controller, even in the environment of frequency variation. To implement full-state feedback control for a grid-connected inverter with an LCL filter, all the state variables should be available. However, the increase in number of sensing devices leads to the rise of cost and complexity for hardware implementation. To overcome this challenge, a discrete-time full-state current observer is introduced to estimate all the system states. When the grid frequency is subject to variation, the discrete-time implementation of the observer in the SRF requires an online discretization process because the system matrix in the SRF includes frequency information. This results in a heavy computational burden for the controller. To resolve such a difficulty, a discrete-time observer in the stationary reference frame is employed in the proposed scheme. In the stationary frame, the discretization of the system model can be accomplished with a simple offline method even in the presence of frequency variation since the system matrix does not include the frequency. To select desirable gains for the full-state feedback controller and full-state observer, an optimal linear quadratic control approach is applied. To validate the practical effectiveness of the proposed frequency-adaptive control, simulation and experimental results are presented.

STATE-FEEDBACK CONTROL OF DISCRETE-TIME STOCHASTIC LINEAR SYSTEMS WITH MARKOVIAN SWITCHING

2020 ◽  
Vol 65 (6) ◽  
pp. 13-22
Author(s):  
Dung Nguyen Trung ◽  
Thu Tran Thi
Keyword(s):  
Feedback Control ◽  
Discrete Time ◽  
State Feedback ◽  
Transition Probabilities ◽  
Sufficient Conditions ◽  
State Feedback Control ◽  
Linear Matrix ◽  
Discrete Time Markov Chain ◽  
Multiplicative Noises ◽  
Stochastic Linear Systems

This paper is concerned with the stabilization problem via state-feedback control of discrete-time jumping systems with stochastic multiplicative noises. The jumping process of the system is driven by a discrete-time Markov chain with finite states and partially known transition probabilities. Sufficient conditions are established in terms of tractable linear matrix inequalities to design a mode-dependent stabilizing state-feedback controller. A numerical example is provided to validate the effectiveness of the obtained result.

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