Robust Control of DFIG Based Wind Energy System Using an H∞ Controller

Haneesh K. M.,Raghunathan T. 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3

Wind Energy Conversion System (WECS) using a Doubly Fed Induction Generator (DFIG) is popular due to its control fl exibility and higher conversion effi ciency, but maintaining the operational stability and optimal effi ciency under dynamic wind conditions is still a control challenge. In this paper, a nonlinear mathematical model for a DFIG based WECS was developed from fundamentals and its characteristics near the operating point were studied. A Proportional Integral (PI) controller and a Linear Quadratic Regulator (LQR) controller were designed to control the system and the behavior of the closed-loop system with these controllers was studied. While the designed PI controller failed to ensure stability, the LQR controller was giving stability but an LQR controller is vulnerable to loss of stability under uncertainties due to parameter variations or changes in operating points. A suboptimal H∞ controller was then synthesized to obtain robust control. The closed-loop system performance of the DFIG system with the proposed controller was found to be stable and superior to PI and LQR controllers in terms of performance

The Ball and Beam System: Cascaded LQR-FLC Design and Implementation

Muhammad Ridho Rosa,Muhammad Zakiyullah Romdlony,Bambang Riyanto Trilaksono 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.1

This paper aims to derive a dynamic model of ball and beam systems (BBS), design, and implement the optimal controller linear quadratic regulator (LQR) with cascaded feedback linearization controller (FLC). It is known that missing information of the parameter of the system model can cause undesired tracking results. The LQR-FLC can solve the tracking problem caused by model uncertainty. The LQR controller, the inner-loop controller, is designed based on the derived BBS dynamics model. Then FLC, the outer-loop controller, is designed to get the desired tracking error dynamics. By using LQR-FLC, one can use the simple PD controller to design the tracking error dynamics. In addition, the estimator is designed to provide the controller with the full-states information. This research is worth investigating because the LQR-FLC scheme for controlling the BBS is missing in the literature. The experiment is carried out using a hardware in loop (HIL) scheme where MATLAB-Simulink is connected to a microcontroller. Simulation and experimental results show the effectiveness of the proposed cascaded LQR-FLC.

자코비안을 이용한 LQR 제어기 학습법

임윤규(Yoon Kyu Lim),정병묵(Byeong Mook Chung) Korean Society for Precision Engineering 2005 한국정밀공학회지 Vol.22 No.8

Generally, it is not easy to get a suitable controller for multi variable systems. If the modeling equation of the system can be found, it is possible to get LQR controller as an optimal solution. This paper suggests an LQR learning method tc design LQR controller without the modeling equation. The proposed algorithm uses the same cost function with errol and input energy as LQR is used, and the LQR controller is trained to reduce the function. In this training process, the; Jacobian matrix that informs the converging direction of the controller is used. Jacobian means the relationship of output variations for input variations and can be approximately found by the simple experiments. In the simulations of 2 hydrofoil catamaran with multi variables, it can be confirmed that the training of LQR controller is possible by using the; approximate Jacobian matrix instead of the modeling equation and this controller is not worse than the traditional LQR controller.

통합 섀시 제어를 위한 LQR의 가중치 변화에 대한 민감도 해석

임성진(Seonjin Yim) 제어로봇시스템학회 2017 제어·로봇·시스템학회 논문지 Vol.23 No.4

This article presents a sensitivity analysis on the weight of the linear quadratic regulator (LQR) for integrated chassis control. Electronic stability control (ESC) and active front steering (AFS) are used as actuators needed to generate a control tire force. After computing the control yaw moment in the upper-level controller, the lower-level controller was used to distribute the control yaw moment into the control tire forces generated by ESC and AFS. In this paper, the LQR was used to design the upper-level controller. The Taguchi method was used to complete a sensitivity analysis on the weight of the linear quadratic (LQ) objective function in the LQR. For the sensitivity analysis, simulation was performed using CarSim, a vehicle simulation package. From the sensitivity analysis, the effect of the LQ objective function weight on the control performance was checked. Based on this sensitivity analysis, it was determined that the weights on lateral acceleration and yaw rate error had the largest effect on the control performance.

Balancing and Velocity Control of a Unicycle Robot Based on the Dynamic Model

Han, Seong I.,Lee, Jang M. Institute of Electrical and Electronics Engineers 2015 IEEE transactions on industrial electronics Vol. No.

<P>This paper presents a dynamic-model-based control scheme for the balancing and velocity control of a unicycle robot. Unicycle robot motion consists of a pitch that is controlled by an in-wheel motor and a roll that is controlled by a reaction wheel pendulum. The unicycle robot lacks an actuator for yaw-axis control, which makes the derivation of the dynamics relatively simple although it may limit the motion control. The Euler-Lagrange equation is applied to derive the dynamic equations of the unicycle robot to implement dynamic speed control. To achieve real-time speed control, a sliding-mode control and a nonzero set-point linear quadratic regulator (LQR) are utilized to guarantee stability while maintaining the desired speed-tracking performance. In the roll controller, a sigmoid-function-based sliding-mode controller has been adopted to minimize switching-function chattering. An LQR controller has been implemented for pitch control to drive the unicycle robot to follow the desired velocity trajectory in real time using the state variables of pitch angle, angular velocity, wheel angle, and angular velocity. The control performance of the two control systems using a single dynamic model has been experimentally demonstrated.</P>

PD제어와 LQR을 이용한 병진 시스템의 제어특성 연구

김택현,정상화,이동하 한국공작기계학회 2001 한국생산제조학회지 Vol.10 No.5

The translation system is made up of springs, masses and a dashpot. This precise piece of equipment is controlled electro-mechanically by a motor and operating program. The control strategy of the system can be changed by spring stiffness, change of mass, and the damping coefficient of the dashpot. This system proves the necessity and effect of a closed loop control. In this paper, PD control experiments were implemented for the translation system. When the notch filter was added on the PD controller, we compared the response characteristics of the two systems. The state feedback controller minimized scalar control gains and the resulting response characteristics of the system were studied using the LQR design. Finally, we improved the response characteristics of the translation system which are rising time, settling time, steady state error, and overshoot. LQR was better as compared with PD control.

Characteristics Comparison of Motion Controllers through Experiments

정승현,왕준,한창욱,박정일,Jung, Seung-Hyun,Wang, Jun,Han, Chang-Wook,Park, Jung-Il Institute of Control 2008 제어·로봇·시스템학회 논문지 Vol.14 No.11

Through the motion control experiment using Industrial Emulator(Model 220 by ECP), the performance comparison of three kinds of controllers such as PID, RIC and LQR was carried out. It was shown that RIC has the best performance in the presence of disturbances such as step one, sinusoidal one and Coulomb friction for the rigid body. LQR using feedback state variables has the best tracking performance far the flexible body. The performance of PID controller is low compared to other controllers, but the design process is simple. The most advanced controller is LQR. In order to attenuate disturbance, an additional state observer should be used to estimate it, making more complex control system. RIC lies between PID and LQR in view of complexity of design. Even though RIC is not complicated, it has good disturbance rejection ability and less tracking error. By considering these aspects, the RIC is suggested as high precision controller to be used in motion control system.

Characteristics Comparison of Motion Controllers through Experiments

Seung Hyun Jung(정승현),Jun Wang(왕준),Chang Wook Han(한창욱),Jung-Il Park(박정일) 제어로봇시스템학회 2008 제어·로봇·시스템학회 논문지 Vol.14 No.11

Through the motion control experiment using Industrial Emulator(Model 220 by ECP), the performance comparison of three kinds of controllers such as PID, RIC and LQR was carried out. It was shown that RIC has the best performance in the presence of disturbances such as step one, sinusoidal one and Coulomb friction for the rigid body. LQR using feedback state variables has the best tracking performance for the flexible body. The performance of PID controller is Jow compared to other controllers, but the design process is simple. The most advanced controller is LQR. In order to attenuate disturbance, an additional state observer should be used to estimate it, making more complex control system. RIC lies between PlD and LQR in view of complexity of design. Even though RIC is not complicated, it has good disturbance rejection ability and less tracking error. By considering these aspects, the RIC is suggested as high precision controller to be used in motion control system.

무인잠수정의 LQR 제어기 설계

배설봉(Seol B. Bae),신동협(Dong H. Shin),권순태(Soon T. Kwon),주문갑(Moon G. Joo) 제어로봇시스템학회 2014 제어·로봇·시스템학회 논문지 Vol.20 No.2

In this paper, An LQR controller is proposed for way-point tracking of AUV (Autonomous Underwater Vehicle). The LQR controller aims at tracking a series of way-points which operator registers arbitrarily in advance. It consists of a depth controller and a steering controller and AUV"s surge speed is assumed varying to consider the dynamic environment of the underwater. In order to show the performance, a conventional state feedback controller is compared with the proposed controller by the simulation using Matlab/Simulink. The parameters of AUV developed by the author"s laboratory are used. In the simulation, we verify that the LQR controller can track all the way-points within 1 m error range under the varying surge speed, which proves the robustness of the LQR controller.

LQR-퍼지논리제어기에 의한 2중 차량 구조 역진자 시스템의 제어

허열(Yue Xu),최병재(Byung-Jae Choi) 한국지능시스템학회 2013 한국지능시스템학회논문지 Vol.23 No.3

임의의 비선형 시스템을 제어하기 위한 새로운 방법의 제어 알고리즘이 널리 보고되고 있으며, 그 유용성을 입증하기 위한 제어 대상 시스템으로 역진자 시스템이 널리 활용되고 있다. 본 논문에서는 스프링으로 연결된 2개의 차량에 장착된 역진자를 제어하는 알고리즘을 제시한다. 여기서 두 개의 차량 중 하나는 구동용, 다른 하나는 역진자를 장착한 무구동용이다. 이를 위한 시스템 모델링을 제시하고, 퍼지논리제어 시스템 기반의 양질의 제어기 설계를 제안한다. 본 논문에서는 퍼지논리제어기의 입력변수로 사용될 6개의 변수를 2개로 축소하기 위하여 LQR(Linar Quadratic Regulator) 기법을 도입하며, 이를 통하여 퍼지논리제어기 설계의 복잡성을 줄일 수 있음을 보인다. 더욱이 개선된 2-입력 퍼지논리제어기의 제어 규칙표가 skew-symmetric의 특성을 가지는 성질로부터 다시 단일입력 퍼지논리제어기 설계를 제안한다. 제안한 방법의 유용성을 입증하기 위하여 시뮬레이션을 수행하며, 이를 통하여 제안한 방법의 우수성을 입증한다. Any new method for controlling a nonlinear system has widely been reported. An inverted pendulum system has typically been used as a target system for demonstrating its usefulness. In this paper, we propose an algorithm to control a flexible joint cart based inverted pendulum system. Two carts are connected with a spring and one is a driving cart and the other is no driving cart with a pole. We here present a system modeling and a good fuzzy logic based control algorithm. We also introduce LQR (Linar Quadratic Regulator) technique for reducing the number of control variables. By using this technique, the number of input variables for a fuzzy logic controller is become only two not six. So the computational complexity is largely reduced. Moreover, a two-input fuzzy logic controller has a control rule table with a skew-symmetric property. And it will lead the design of a single-input fuzzy logic controller. In order to demonstrate the usefulness of the proposed method and prove the superiority of the proposed method, some computer simulations are presented..