Kaitwanidvilai, Somyot

Preferred name

Alternative Name

Kaitwanidvilai, S.

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School of Engineering

somyot.ka@kmitl.ac.th

Now showing 1 - 10 of 19

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Fixed-structure mixed sensitivity/model reference control using evolutionary algorithms
(2009-01-01)
Srithongchai, Pitsanu
;
Olranthichachat, Piyapong
;
Kaitwanidvilai, Somyot
This paper proposes a mixed sensitivity/model reference control using evolutionary algorithms. The proposed technique can solve the problem of complicated and high order controller of conventional H∞optimal control. In addition, time domain specifications such as overshoot, undershoot, rise time can be incorporated in the design by formulating the appropriate fitness function of compact genetic algorithms. By the proposed approach, robustness and performance in terms of frequency domain and time domain specifications can be achieved simultaneously. Simulation results in a servo system verify the effectiveness of the proposed technique.
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A novel robust load frequency controller for a two area interconnected power system using LMI and compact genetic algorithms
(2009-12-01)
Koisap, Chamnan
;
Kaitwanidvilai, Somyot
This paper proposes a new technique for designing a fixed-structure robust load frequency controller for a two area interconnected power system. The proposed technique uses Linear Matrix Inequality (LMI) method to form an initial solution, and then the global search algorithm, Compact Genetic Algorithm (cGA), is adopted for evaluating the final solution. By combining both techniques, LMI and cGA, a better solution in terms of robust performance can be achieved. Infinity norm from disturbances to states are formulated as the cost function in our optimization. The performance of the designed system is investigated in comparison with the conventional H infinity loop shaping controller, the robust controller designed by LMI method and the reduced order robust controller by Hankel norm model reduction method. As results indicated, stability margin of our proposed controller is better than that of the static controller designed by LMI method and the reduced order robust controller. In addition, order of the proposed controller is much lower than that of conventional robust loop shaping controller, making it easy to implement in practice. ©2009 IEEE.
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Robust voltage stabilization in an isolated wind-diesel power system using pso based-fixed structure H∞ loop shaping control
(2009-07-30)
Vachyirasricirikul, Sitthidet
;
Ngamroo, Issarachai
;
Kaitwanidvilai, Somyot
It is well known that the power system controller designed by H∞ control is complicated, high order and impractical. In power system applications, practical structures such as proportional integral derivative (PID) etc., are widely used, because of their simple structure, less number of tuning parameters and low-order. However, tuning of controller parameters to achieve a good performance and robustness is based on designer's experiences. To overcome this problem, this paper proposes a fixed structure robust H∞ loop shaping control to design Static Var Compensator (SVC) and Automatic Voltage Regulator (AVR) for robust stabilization of voltage fluctuation in an isolated wind-diesel hybrid power system. The structure of the robust controller of SVC and AVR is specified by a PID controller. In the system modeling, a normalized coprime factorization is applied to represent possible unstructured uncertainties in the power system such as variation of system parameters, generating and loading conditions etc. Based on the H∞ loop shaping, the performance and robust stability conditions are formulated as the optimization problem. The particle swarm optimization is applied to solve for PID control parameters of SVC and AVR simultaneously. Simulation studies confirm the control effect and robustness of the proposed control. © 2009 The Institute of Electrical Engineers of Japan.
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The impact of deadtime effect on unwanted harmonics conducted emission of PWM inverters
(2000-01-01)
Kaitwanidvilai, S.
;
Khan-Ngern, W.
;
Panarut, M.
This paper presents an analysis of unwanted harmonics spectra impacted by deadtime effect which is the one of the conducted emission sources at the load terminal of PWM inverters. The unwanted voltage from this impact is shown that it is depend upon not only load current direction, deadtime interval, DC link voltage but also amplitude and phasor of the load. The analysis with Fourier transform theory is clearly shown this phenomena and the simulated and measured results for harmonics injection PWM and discontinuous PWM with deadtime of 2% and 4% of switching time are presented in this paper. The deadtime compensated show the improvement for PWM inverter performance. The results show closed agreement between both of results with a good support from the analysis and simulation.
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Robust pitch controller design in hybrid wind-diesel power generation system
(2008-09-23)
Cuk Supriyadi, A. N.
;
Ngamroo, I.
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Kaitwanidvilai, S.
;
Kunakorn, A.
;
Hashiguchi, T.
In this paper, the robust control design of pitch controller for frequency control in a hybrid wind-diesel power generation system is proposed. The structure of the pitch controller is a 1<sup>st</sup>-order lead-lag compensator. To take system uncertainties into account, the coprime factorization is applied in system modeling. To obtain the controller parameters, the performance and stability conditions of H<inf>∞</inf> loop shaping technique are used to formulate the optimization problem. The genetic algorithm is employed to solve the problem. Simulation studies show the frequency control effect and robustness of the proposed controller against system uncertainties in comparison with a variable structure pitch control. ©2008 IEEE.
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Genetic algorithm based fixed-structure H∞ loop shaping control of a buck-boost converter
(2008-01-01)
Olranthichachat, P.
;
Saenthon, A.
;
Kaitwanidvilai, S.
H∞ loop shaping is a feasible method for designing a robust controller; however, the controller designed by this method is complicated and has high order. It is not easy to implement this controller in practice. To overcome this problem, we propose an algorithm, GA based fixed-structure H∞ loop shaping control, to design a robust controller. In the proposed technique, genetic algorithm is used to solve the H∞ loop shaping design problem under a structure specified controller. To compare performance, conventional H∞ loop shaping, proposed robust controller and conventional ISE method are investigated. Results of simulation demonstrate the advantages of a simple structure and robustness against plant perturbations and disturbances of the proposed controller. In this paper, the proposed technique is adopted to design a robust controller of a PCMC buck-boost converter. Experiments are performed to verify the effectiveness of the proposed technique. © 2008 IEEE.
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Application of electrolyzer system to enhance frequency stabilization effect of microturbine in a microgrid system
(2009-09-01)
Vachirasricirikul, Sitthidet
;
Ngamroo, Issarachai
;
Kaitwanidvilai, Somyot
It is well known that the power output of microturbine can be controlled to compensate for load change and alleviate the system frequency fluctuations. Nevertheless, the microturbine may not adequately compensate rapid load change due to its slow dynamic response. Moreover, when the intermittent power generations from wind power and photovoltaic are integrated into the system, they may cause severe frequency fluctuation. In order to study the fast dynamic response, this paper applies electrolyzer system to absorb these power fluctuations and enhance the frequency control effect of microturbine in the microgrid system. The robust coordinated controller of electrolyzer and microturbine for frequency stabilization is designed based on a fixed-structure H<inf>∞</inf> loop shaping control. Simulation results exhibit the robustness and stabilizing effects of the proposed coordinated electrolyzer and microturbine controllers against system parameters variation and various operating conditions. Crown Copyright © 2009.
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Deadtime effect on three phase unbalanced load for PWRR inverters
(2000-01-01)
Khan-Ngern, Werachet
;
Kaitwanidvilai, Somyot
In this paper, the analysis of deadtime effect on unbalanced load for three phase P WM inverters. The actual error voltage of unbalanced is shown that it is depend upon not only load current direction, but also amplitude and phasor of the load. The simulated and measured results for sinusoidal P WM, harmonics injection P WM and discontinuous P WM are analyzed with 4.88 p deadtime of 2% of switching time which is shown close agreement between both of results with a good support from the analysis.
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Design of robust SVC for voltage control in an isolated wind-diesel hybrid power system
(2008-10-06)
Vachirasricirikul, S.
;
Ngamroo, I.
;
Kaitwanidvilai, S.
This paper focuses on a new robust control design of Static Var Compensator (SVC) for voltage control in an isolated wind-diesel hybrid power system. The proposed method is based on the H<inf>∞</inf> loop shaping technique and genetic algorithm (GA). The structure of the controller is a proportional integral (PI) controller with single input. In the design, system uncertainties are modeled by a normalized coprime factorization. The performance and robust stability conditions of the designed system satisfying the H<inf>∞</inf> loop shaping are formulated as the objective function in the optimization problem. The GA is applied to solve an optimization problem and to achieve control parameters. Simulation studies show the effectiveness and robustness of the proposed method. © 2008 IEEE.
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H∞ loop shaping-based robust control design of PSS and TCSC for dynamic stability enhancement
(2008-10-06)
Cuk Supriyadi, A. N.
;
Ngamroo, I.
;
Kaitwanidvilai, S.
;
Kunakorn, A.
;
Hashiguchi, T.
In this paper, the robust control design of power system stabilizer (PSS) and thyristor controlled series capacitor (TCSC) for enhancement of power system dynamic stability is proposed. To take system uncertainties such as variations of system parameters, several loading conditions etc., into account, the normalized coprime factorization is used to represent unstructured uncertainties in the system. The H∞ loop shaping technique is applied to design robust PSS and TCSC controllers. Simulation results in a single machine infinite bus system show that the performance and robustness of the proposed H∞ controllers of PSS and TCSC are superior to those of the conventional PSS and TCSC. © 2008 IEEE.

Kaitwanidvilai, Somyot

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