Phayao, Thailand

University of Phayao

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Pothi N.,University of Phayao
2017 2nd International Conference on Control and Robotics Engineering, ICCRE 2017 | Year: 2017

This paper proposes a new approach flux-weakening control strategy of the separately excited DC machine. The proposed method is based on the closed-loop speed control in which the field current is independently controlled to adjust the flux-linkage in the flux-weakening operation. In order to achieve the maximum torque in the constant-torque region, the maximum field current is employed, while it is gradually modified in the constant-power region, following the increased speed, by the voltage regulation part. The modification current is determined based on the utilization of the difference voltages between command and voltage limit of DC-DC converter. The proposed method exhibits advantages such as high torque at low speed, wider operating speed range, robustness against machine parameters, and high efficiency in the constant-power region rather than without flux-weakening control. The effectiveness of the proposed method is verified by simulation results. © 2017 IEEE.


Mekruksavanich S.,University of Phayao
Proceedings of the IEEE International Conference on Software Engineering and Service Sciences, ICSESS | Year: 2017

Diabetes has recently played an important role in the considerable indisposition of humanity. The diabetes patients are in a condition resulting from defects in insulin secretion with long range harm, dysfunction and failure of various human organs. Potential medical diagnosis of the disease diabetes is essential, including medical applications. However, limitations in representing the meaning and content of the domain knowledge for support of the search process for knowledge from a variety of user perceptions are considerable among these applications. In this paper, a medical expert system for diagnosis of diabetes is proposed. The diabetes ontology is developed using the OWL format with 9 sub-classes. The interval results with the weighted OWA similarity algorithm are expressed for easy interpretation by users. The expert system is developed in the form of a web-based application with web service architecture. An overall consistency rate of 90.7% was achieved with test data from 65 patients. The obtained results properly show that the system can help to diagnose diabetes early on and serve as a guide for people with diabetes to monitor the disease. It is quite possible that the proposed medical expert system discussed in the current work can be properly applied to other biological datasets to deal with the problems of disease diagnosis effectively. © 2016 IEEE.


Vachirasricirikul S.,University of Phayao | Ngamroo I.,King Mongkut's University of Technology Thonburi
Applied Energy | Year: 2011

This paper proposes a new robust controller design of heat pump (HP) and plug-in hybrid electric vehicle (PHEV) for frequency control in a smart microgrid (MG) system with wind farm. The intermittent power generation from wind farm causes severe frequency fluctuation in the MG. To alleviate frequency fluctuation, the smart control of power consumption of HP and the power charging of PHEV in the customer side can be performed. The controller structure of HP and PHEV is a proportional integral derivative (PID) with single input. To enhance the performance and robustness against system uncertainties of the designed controller, the particle swarm optimization based-mixed H2/H∞ control is applied to design the PID controllers of HP and PHEV. Simulation studies confirm the superior robustness and frequency control effect of the proposed HP and PHEV controllers in comparison to the conventional controller. © 2011.


Pahasa J.,University of Phayao | Ngamroo I.,King Mongkut's University of Technology Thonburi
IEEE Transactions on Smart Grid | Year: 2015

This paper proposes plug-in hybrid electric vehicles bidirectional charging/discharging and state of charge (SoC) control for a microgrid frequency stabilization using a multiple model predictive control (MMPC). The MMPC is the improved version of a model predictive control (MPC) for working with multiple operating condition of the system. The MPC is an effective model-based prediction which calculates the future control signals by optimization of a quadratic programming based on the plant model, past manipulate, and control signals of the system. By optimization of an electric vehicle power control signal at each time instant, as well as changing the MPC by electric vehicle battery SoC, the proposed MMPC is able to improve the frequency stabilization of the microgrid effectively. © 2010-2012 IEEE.


Vachirasricirikul S.,University of Phayao | Ngamroo I.,King Mongkut's University of Technology Thonburi
IEEE Transactions on Smart Grid | Year: 2014

In the smart grid, the large scale wind power penetration tends to expand vastly. Nevertheless, due to the intermittent power generation from wind, this may cause a problem of large frequency fluctuation when the load-frequency control (LFC) capacity is not enough to compensate the unbalance of generation and load demand. Also, in the future transport sector, the plug-in hybrid electric vehicle (PHEV) is widely expected for driving in the customer side. Generally, the power of PHEV is charged by plugging into the home outlets as the dispersed battery energy storages. Therefore, the vehicle-to-grid (V2G) power control can be applied to compensate for the inadequate LFC capacity. This paper focuses on the new coordinated V2G control and conventional frequency controller for robust LFC in the smart grid with large wind farms. The battery state-of-charge (SOC) is controlled by the optimized SOC deviation control. The structure of frequency controller is a proportional integral (PI) with a single input. To enhance the robust performance and robust stability against the system uncertainties, the PI controller parameters and the SOC deviation are optimized simultaneously by the particle swarm optimization based on the fixed structure mixed H2/H\infty control. Simulation results show the superior robustness and control effect of the proposed coordinated controllers over the compared controllers. © 2013 IEEE.


Vachirasricirikul S.,University of Phayao | Ngamroo I.,King Mongkut's University of Technology Thonburi
International Journal of Electrical Power and Energy Systems | Year: 2012

This paper proposes a new robust controller design of microturbine (MT) and electrolyzer (ES) in a control and monitoring system (CMS) for frequency stabilization in a microgrid system with plug-in hybrid electric vehicles (PHEVs). In the studied microgrid, the MT is normally used to provide the main power to the loads while the ES absorbs the power from the system to produce the hydrogen as the fuel input for the power generation of the fuel cell. On the other hand, the large numbers of PHEVs are utilized in the consumer side. The concurrent charging powers of PHEVs cause a problem of severe frequency fluctuation in the microgrid. To solve this problem, the frequency stabilization of CMS is performed by controlling the power output of MT and ES. The controller structure of MT and ES is a proportional integral with a single input. To enhance the tracking performance and the robustness against system uncertainties of the designed MT and ES controllers, the control parameters are optimized by shuffled frog leaping algorithm based on specified-structure mixed H 2/H ∞ control technique. Simulation results not only show the frequency stabilization effect against the random charging power of PHEVs but also the high robustness of the proposed robust MT and ES controllers against the system parameters variation. © 2012 Elsevier Ltd. All rights reserved.


Cholamjiak P.,University of Phayao | Suantai S.,Chiang Mai University
Journal of Global Optimization | Year: 2012

We first investigate strong convergence of the sequence generated by implicit and explicit viscosity approximation methods for a one-parameter nonexpansive semigroup in a real Banach space E which has a uniformly Gâteaux differentiable norm and admits the duality mapping j φ, where φ is a gauge function on [0, ∞). The main results also improve and extend some known results concerning the normalized duality mapping in the literature. © 2011 Springer Science+Business Media, LLC.


Prasatkhetragarn A.,University of Phayao
Ferroelectrics | Year: 2011

Ceramic in PZT-PFN system with a formula 0.9Pb(Zr1/2Ti 1/2)O3-0.1Pb(Fe1/3Nb2/3)O 3 was prepared by a conventional solid state mixed oxide technique. The phase formation behavior and microstructure were investigated using X-ray diffraction (XRD) and scanning electronmicroscopy (SEM), respectively. The dielectric properties of the compound were examined and discussed. Phase-pure perovskite of the 0.9PZT-0.1PFN ceramic was obtained at sintering temperature of 1100°C. The average grain size decreased significantly from 1.27 μ m in PZT to 90.2 nm in 0.9PZT-0.1PFN. In addition, the dielectric properties of the ceramic showed two phase transitions between rhombohedral to tetragonal ferroelectric phases, and then tetragonal ferroelectric to cubic paraelectric phases at transition temperature of 150°C and 350°C, respectively. Copyright © Taylor & Francis Group, LLC.


Rakpenthai C.,University of Phayao | Uatrongjit S.,Chiang Mai University | Premrudeeprechacharn S.,Chiang Mai University
IEEE Transactions on Power Systems | Year: 2012

This paper addresses the state estimation of a power system whose network parameters are known to be within certain tolerance bounds. The power system is assumed to be fully observable by having enough phasor measurement units installed. Using synchronized phasor measurement data and state variables expressed in rectangular forms, the state estimation under the transmission line parameter uncertainties is formulated based on the weight least square criterion as a parametric interval linear system of equations. The solutions are obtained as interval numbers representing the outer bound of state variables. The proposed method is also extended to a power system with mixed phasor and conventional power measurements. A technique based on affine arithmetic for converting state variable into polar form is also presented. The proposed method has been implemented using MATLAB and INTLAB toolbox and applied to some IEEE test systems. The numerical experiment results indicate that, in shorter computation time, the proposed algorithm can find the outer bounds that are close to those computed by performing Monte Carlo simulations or by solving constrained nonlinear optimization problems. © 2006 IEEE.


Sapbamrer R.,University of Phayao | Hongsibsong S.,Chiang Mai University
Archives of Environmental Contamination and Toxicology | Year: 2014

This study investigated organophosphorus (OP) residues in vegetables from 27 farms, 106 markets, and 1 supermarket around Kwan Phayao Lake, Northern Thailand, between August and September 2013. Types of vegetables sampled were all vegetables cultivated or sold around the study site. The most common OP pesticides detected in farm samples were chlorpyrifos (50 %), malathion (31.8 %), monocrotophos (31.8 %), diazinon (13.6 %), omethoate (13.6 %), and dicrotophos (9.1 %). The most common OP pesticides detected in market samples were chlorpyrifos (33.9 %), diazinon (18.6 %), parathion-methyl (3.4 %), profenofos (3.4 %), primiphos-ethyl (3.4 %), and fenitrothion (1.7 %). The OP pesticides detected in supermarket samples were chlorpyrifos (33.3 %), and diazinon (66.7 %). Among the compounds detected, chlorpyrifos was detected in most of the vegetable samples from all sources. The highest chlorpyrifos level in farm samples were found in lemon balm (2.423 mg/kg) followed by Vietnamese coriander (0.835 mg/kg), and cowpea (0.027 mg/kg). The highest level in markets samples were found in garlic (7.785 mg/kg) followed by Chinese cabbage (2.864 mg/kg) and Vietnamese coriander (1.308 mg/kg). Residues from supermarket samples were found only in parsley (0.027 mg/kg). The findings showed that 16 samples (59.3 %) from farms and 14 samples (13.2 %) from markets contained OP residues at or above the maximum residue limits established by the European Union. It is concluded that awareness, safety education, and strict regulation of pesticide use are necessary. © Springer Science+Business Media New York 2014.

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