• 한국지진공학회논문집
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• 제6권6호
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• pp.49-53
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• 2002

가중행렬은 일반적인 최적 제어 설계에서 우선적으로 필요하지만 일반적으로 제어 설계자들 이 경험적 지식에 의존하고 있다. 이 논문은 구조물의 에너지를 고려한 최적제어기의 가중행렬을 결정하는 체계적인 절차를 제시하였다. 최적제어기는 LQR과 ILQR로 구분될 수 있다. 구조물의 총에너지를 고려한 Lyapunov 함수를 적용하고, 이로부터 유도된 식이 음수라는 상태를 이용하면 가중행렬을 어렵지 않게 구할 수 있다. 이러한 방법으로 산정된 가중행렬을 이용하여 LQR과 ILQR제어기를 설계하고 제어효율을 입증하였다.

• 풍력에너지저널
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• 제2권1호
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• pp.74-81
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• 2011

This paper deals with the application of LQ control to the power curve tracking control of wind turbine. However, two more additional tasks are required to apply the LQR theory to wind turbine control. One is the tracking problem instead of regulation, because the wind turbine is controlled as variable speed and variable pitch. The other is LQ integral control., because the rotor speed should be tightly controlled without any steady state error. Starting from the analysis of wind characteristics, design requirement of a wind turbine control system is defined. A design procedure of LQ tracking with integral control is introduced. The performance of LQ tracking system is analyzed and evaluated by numeric simulation.

• 에너지공학
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• 제13권1호
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• pp.68-74
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• 2004

본 논문에서는 전압 sag 보상을 위한 배전용 정지형 보상기 (DSTATCOM) 제어기를 설계하고 PSCAD/EMTDC로 확인하였다. DSIATCOM의 전류성분을 dq분해 해석을 통하여 상태방정식을 유도하고 부하모델과 네트워크의 제약조건을 고려하여 결합 모델을 제시하였다. 1선 지락 사고시 PI 제어기보다 LQR 제어기의 응답 특성이 우수함을 검증하고 전압 Sag가 개선됨을 보였다.

• 한국정밀공학회지
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• 제22권8호
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• pp.34-41
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• 2005

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 control as an optimal solution. This paper suggests an LQR learning method to design LQR controller without the modeling equation. The proposed algorithm uses the same cost function with error 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 a 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.

• Smart Structures and Systems
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• 제23권3호
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• pp.243-261
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• 2019

This paper introduces an appropriate technique to estimate the weighting matrices used in the linear quadratic regulator (LQR) method for active structural control. For this purpose, a parameter is defined to regulate the relationship between the structural energy and control force. The optimum value of the regulating parameter, is determined for single degree of freedom (SDOF) systems under seismic excitations. In addition, the suggested technique is generalized for multiple degrees of freedom (MDOF) active control systems. Numerical examples demonstrate the robustness of the proposed method for controlled buildings under a wide range of seismic excitations.

• Journal of Power Electronics
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• 제13권6호
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• pp.1024-1031
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• 2013

This paper addresses linear quadratic regulation (LQR) for variable speed variable pitch wind turbines. Because of the inherent nonlinearity of wind turbines, a set of operating conditions is identified and then a LQR controller is designed for each of the operating points. The feedback controller gains are then interpolated linearly to get a control law for the entire operating region. In addition, the aerodynamic torque and effective wind speed are estimated online to get the gain-scheduling variable for implementing the controller. The potential of this method is verified through simulation with the help of MATLAB/Simulink and GH Bladed. The performance and mechanical load when using LQR are also compared with those obtained when using a PI controller.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.557-572
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• 2004

Control systems are used to limit structural lateral deflections during large external loads such as winds and earthquakes. Most recently, the semi-active control approach has grown in popularity due to inexpensive control devices that consume little power. As a result, recently designed control systems have employed many semi-active control devices for the control of a structure. In the future, it is envisioned that structural control systems will be large-scale systems defined by high actuation and sensor densities. Decentralized control approaches have been used to control large-scale systems that are too complex for a traditional centralized approach, such as linear quadratic regulation (LQR). This paper describes the derivation of energy market-based control (EMBC), a decentralized approach that models the structural control system as a competitive marketplace. The interaction of free-market buyers and sellers result in an optimal allocation of limited control system resources such as control energy. The Kajima-Shizuoka Building and a 20-story benchmark structure are selected as illustrative examples to be used for comparison of the EMBC and centralized LQR approaches.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.475-482
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• 2002

This paper provides the systematic procedure to determine the weighting matrices of optimal controllers considering structural energy. Optimal controllers consist of LQR and ILQR. The weighting matrices are needed first in the conventional optimal control design strategy. However, they are in general dependent on the experienced knowledge of controll designers. Applying the Lyapunov function to the total structural energy and using the contrition that its derivative is negative, we can determine the weighting matrices without difficulty. It is proven that the control efficiency is achieved well for LQR and ILQR.

• 한국항공우주학회지
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• 제30권8호
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• pp.71-77
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• 2002

본 논문에서는 강성 중앙동체에 끝단 질량을 갖는 두 개의 유연구조물이 부착되어 있는 구조 모델의 선회기동과 진동억제를 동시에 제어하는 문제를 고려하였다. 구조모델의 선형 운동방정식을 구하기 위해 유한요소법을 사용하였다. 우주구조물 모델의 LQR문제에 있어서 물리적 의미를 갖는 성능지수를 제공하는 간단한 방법을 제안하였다. 제안된 성능지수는 일반적으로 사용하는 에너지 형식의 성능지수와 비교할 때 수학적으로는 큰 차이가 없으나 물리적으로는 의미있는 차이를 갖는다. 특수해 방법을 사용하여 부등호 제어 제약조건이 있는 시변 LQR문제를 해결하는 수치적 절차를 소개하였다.

• Nuclear Engineering and Technology
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• 제29권1호
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• pp.68-77
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• 1997

The reactor power control system is described in the fashion of the order increased LQR system. To obtain the optimal state feedback gain vectors, the weighting matrix of the performance function should be determined. Since the contentional method has some limitations, stochastic searching methods are investigated to optimize the LQR weighting matrix using the modified genetic algorithm combined with the simulated annealing, a new optimizing tool named the hybrid MGA-SA is developed to determine the weighting parameters of the LQR system. This optimizing tool provides a more systematic approach in designing the LQR system. Since it can be easily incorporated with any forms of the cost function, it also provides the great flexibility in the optimization problems.