The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Xiaoming Zha - One of the best experts on this subject based on the ideXlab platform.
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a conservatism free large signal stability analysis method for dc microgrid based on Mixed Potential Theory
IEEE Transactions on Power Electronics, 2019Co-Authors: Jianbo Jiang, Xiaoming Zha, Fei Liu, Shangzhi Pan, Wenjun Liu, Chao Chen, Lidong HaoAbstract:Large disturbance scenarios, such as pulse power load operation and load switching are commonly seen in the operation of dc microgrids. The Mixed Potential Theory-based large-signal stability (LSS) analysis is a simple and practical method for investigating the LSS of dc microgrids. However, this method is characterized by conservatism, and produces conservative stability criterion results. When they are applied to the parameter designs of dc microgrids, they create excessive control parameter redundancies; when used for running status estimations, they may cause the system to be misjudged as unstable, and trigger unnecessary protective actions when the system runs into the conservative region. This paper presents a comprehensive analysis of the conservatism, revealing its main causes to be the idealization of the load converter's response characteristics, and the lack of refined models. It then proposes a novel, improved analysis method for transient response characteristics of the load converter. Experimental and simulation results using the improved method have validated it by showing that the conservatism of the traditional method had been eliminated, and the stability criterion obtained was more accurate.
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bifurcation and large signal stability analysis of three phase voltage source converter under grid voltage dips
IEEE Transactions on Power Electronics, 2017Co-Authors: Meng Huang, Yu Peng, Chi K Tse, Yushuang Liu, Jianjun Sun, Xiaoming ZhaAbstract:Three-phase voltage source converters (VSCs) are commonly used as power flow interface in ac/dc hybrid power systems. The ac power grid suffers from unpredictable short-circuit faults and power flow fluctuations, causing undesirable grid voltage dips. The voltage dips may last for a short time or a long duration, and vary the working conditions of VSCs. Due to their nonlinear characteristics, VSCs may enter abnormal operating mode in response to voltage dips. In this paper, the transient response of three-phase VSCs under practical grid voltage dips is studied and a catastrophic bifurcation phenomenon is identified in the system. The converter will exhibit an irreversible instability after the dips. The expanded magnitude of ac reactive current may cause catastrophic consequence for the system. A full-order eigenvalue analysis and a reduced-order Mixed-Potential-Theory-based analysis are adopted to reveal the physical origin of the large-signal instability phenomenon. The key parameters of the system are identified and the boundaries of instability are located. The bifurcation phenomenon and a set of design-oriented stability boundaries in some chosen parameter space are verified by cycle-by-cycle simulations and experimental measurement on a practical grid-connected VSC prototype.
Toshiyuki Osakai - One of the best experts on this subject based on the ideXlab platform.
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sophisticated design of pvc membrane ion selective electrodes based on the Mixed Potential Theory
Analytical Chemistry, 2013Co-Authors: Maya Imoto, Toru Sakaki, Toshiyuki OsakaiAbstract:The Mixed Potential (MP) Theory was successfully utilized to design an ionophore-based polyvinyl chloride (PVC) membrane K+ ion-selective electrode (ISE). Prior to the application of the MP Theory, the transfer of K+ and interfering ions (Na+, Li+, and H+) facilitated by bis(benzo-15-crown-5) (BB15C5) or dibenzo-18-crown-6 (DB18C6) at a micro PVC membrane/water interface was studied by ion-transfer voltammetry (ITV). The reversible half-wave Potentials were then obtained for the facilitated transfer of the ions. Using such voltammetric data and the literature data about diffusion coefficients of ions, we could well-predict the Potential responses of the BB15C5- or DB18C6-based K+ ISE, as the function of the concentrations of primary and interfering ions, and also of the counterion for K+ [e.g., tetrakis(4-chlorophenyl)borate] added to the membrane. Thus, the MP Theory has been proven to be useful to optimize the membrane composition for a higher ion selectivity and a lower detection limit. It has also bee...
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application of the Mixed Potential Theory to the interpretation of the Potential response of a pvc membrane ion selective electrode for desipramine
Analytical Sciences, 2012Co-Authors: Toshiyuki Osakai, Maya Imoto, Yoshitsugu Sato, Toru SakakiAbstract:The Potential response of an ion-exchanger type PVC ion-selective electrode (ISE) for a drug ion, desipramine + (DES + ), was analyzed by a Mixed-Potential (MP) Theory proposed previously. The transfer of DES + and its analogous ions, imipramine + (IMP + ) and neostigmine + (NEO + ), at a micro ο-nitrophenyl octyl ether/water interface was studied by ion-transfer voltammetry; also, the standard ion-transfer Potentials (Δ W Of o j) of the ions were then determined. The application of MP Theory with the Δ W Of o values successfully explained the under-Nernstian response of DES + -ISE due to interference from IMP + or NEO + . In this study, a universal method based on numerical calculations was developed for evaluating MP associated with plural interfering ions, which was impossible in the previous method based on analytical equations. Using the universal method, we could well predict the detection limit of DES + -ISE theoretically. The MP Theory is promising for the sophisticated design of ISEs, which is not due to conventional “trial-and-error’’ procedures.
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interpretation of the Potential response of pvc membrane ion selective electrodes based on the Mixed Potential Theory
Journal of Electroanalytical Chemistry, 2012Co-Authors: Toshiyuki Osakai, Maya Imoto, Yoshitsugu Sato, Toru SakakiAbstract:Abstract Previously, an excellent Theory was proposed for understanding the Potential response of liquid membrane ion-selective electrodes (ISEs), which was based on a concept of zero-current Potential or “Mixed Potential (MP)” of the interface between the liquid membrane and a sample solution containing interfering ions. Unfortunately, however, the MP Theory has not been utilized explicitly in the development of the most popular, polyvinyl chloride (PVC) membrane ISEs, because the Theory has not been verified by using the PVC membrane/water interface. In this study, we have successfully employed a micro PVC membrane/water interface to perform voltammetric measurements for the interfacial transfer of ions, including tetramethylammonium (TMA+), tetraethylammonium (TEA+), and tetrapropylammonium (TPrA+) ions. Using the thus obtained voltammetric data (i.e., the standard ion-transfer Potentials), the Potential response of a PVC membrane TEA+-ISE in the presence of TMA+ or TPrA+ as the interfering ion could be well elucidated by the MP Theory. This Theory would be available for the sophisticated design of high performance ISEs, which is not determined by conventional “trial-and-error” procedures.
Toru Sakaki - One of the best experts on this subject based on the ideXlab platform.
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sophisticated design of pvc membrane ion selective electrodes based on the Mixed Potential Theory
Analytical Chemistry, 2013Co-Authors: Maya Imoto, Toru Sakaki, Toshiyuki OsakaiAbstract:The Mixed Potential (MP) Theory was successfully utilized to design an ionophore-based polyvinyl chloride (PVC) membrane K+ ion-selective electrode (ISE). Prior to the application of the MP Theory, the transfer of K+ and interfering ions (Na+, Li+, and H+) facilitated by bis(benzo-15-crown-5) (BB15C5) or dibenzo-18-crown-6 (DB18C6) at a micro PVC membrane/water interface was studied by ion-transfer voltammetry (ITV). The reversible half-wave Potentials were then obtained for the facilitated transfer of the ions. Using such voltammetric data and the literature data about diffusion coefficients of ions, we could well-predict the Potential responses of the BB15C5- or DB18C6-based K+ ISE, as the function of the concentrations of primary and interfering ions, and also of the counterion for K+ [e.g., tetrakis(4-chlorophenyl)borate] added to the membrane. Thus, the MP Theory has been proven to be useful to optimize the membrane composition for a higher ion selectivity and a lower detection limit. It has also bee...
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application of the Mixed Potential Theory to the interpretation of the Potential response of a pvc membrane ion selective electrode for desipramine
Analytical Sciences, 2012Co-Authors: Toshiyuki Osakai, Maya Imoto, Yoshitsugu Sato, Toru SakakiAbstract:The Potential response of an ion-exchanger type PVC ion-selective electrode (ISE) for a drug ion, desipramine + (DES + ), was analyzed by a Mixed-Potential (MP) Theory proposed previously. The transfer of DES + and its analogous ions, imipramine + (IMP + ) and neostigmine + (NEO + ), at a micro ο-nitrophenyl octyl ether/water interface was studied by ion-transfer voltammetry; also, the standard ion-transfer Potentials (Δ W Of o j) of the ions were then determined. The application of MP Theory with the Δ W Of o values successfully explained the under-Nernstian response of DES + -ISE due to interference from IMP + or NEO + . In this study, a universal method based on numerical calculations was developed for evaluating MP associated with plural interfering ions, which was impossible in the previous method based on analytical equations. Using the universal method, we could well predict the detection limit of DES + -ISE theoretically. The MP Theory is promising for the sophisticated design of ISEs, which is not due to conventional “trial-and-error’’ procedures.
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interpretation of the Potential response of pvc membrane ion selective electrodes based on the Mixed Potential Theory
Journal of Electroanalytical Chemistry, 2012Co-Authors: Toshiyuki Osakai, Maya Imoto, Yoshitsugu Sato, Toru SakakiAbstract:Abstract Previously, an excellent Theory was proposed for understanding the Potential response of liquid membrane ion-selective electrodes (ISEs), which was based on a concept of zero-current Potential or “Mixed Potential (MP)” of the interface between the liquid membrane and a sample solution containing interfering ions. Unfortunately, however, the MP Theory has not been utilized explicitly in the development of the most popular, polyvinyl chloride (PVC) membrane ISEs, because the Theory has not been verified by using the PVC membrane/water interface. In this study, we have successfully employed a micro PVC membrane/water interface to perform voltammetric measurements for the interfacial transfer of ions, including tetramethylammonium (TMA+), tetraethylammonium (TEA+), and tetrapropylammonium (TPrA+) ions. Using the thus obtained voltammetric data (i.e., the standard ion-transfer Potentials), the Potential response of a PVC membrane TEA+-ISE in the presence of TMA+ or TPrA+ as the interfering ion could be well elucidated by the MP Theory. This Theory would be available for the sophisticated design of high performance ISEs, which is not determined by conventional “trial-and-error” procedures.
Lidong Hao - One of the best experts on this subject based on the ideXlab platform.
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a conservatism free large signal stability analysis method for dc microgrid based on Mixed Potential Theory
IEEE Transactions on Power Electronics, 2019Co-Authors: Jianbo Jiang, Xiaoming Zha, Fei Liu, Shangzhi Pan, Wenjun Liu, Chao Chen, Lidong HaoAbstract:Large disturbance scenarios, such as pulse power load operation and load switching are commonly seen in the operation of dc microgrids. The Mixed Potential Theory-based large-signal stability (LSS) analysis is a simple and practical method for investigating the LSS of dc microgrids. However, this method is characterized by conservatism, and produces conservative stability criterion results. When they are applied to the parameter designs of dc microgrids, they create excessive control parameter redundancies; when used for running status estimations, they may cause the system to be misjudged as unstable, and trigger unnecessary protective actions when the system runs into the conservative region. This paper presents a comprehensive analysis of the conservatism, revealing its main causes to be the idealization of the load converter's response characteristics, and the lack of refined models. It then proposes a novel, improved analysis method for transient response characteristics of the load converter. Experimental and simulation results using the improved method have validated it by showing that the conservatism of the traditional method had been eliminated, and the stability criterion obtained was more accurate.
Siew Hwa Chan - One of the best experts on this subject based on the ideXlab platform.
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physical principles for the calculation of equilibrium Potential for co electrolysis of steam and carbon dioxide in a solid oxide electrolyzer cell soec
Electrochimica Acta, 2014Co-Authors: Jan Pawel Stempien, Siew Hwa Chan, Meng NiAbstract:Abstract This paper reports a comparative study on the calculation of equilibrium Potential (also known as Open Circuit Voltage) of co-electrolysis of H 2 O and CO 2 in a Solid Oxide Electrolyzer Cell. We start with the thorough examination of literature and investigation of physical principles governing the development of such a Potential difference. Based on that review, we compare the use of three different models. A standard model refers to the use of Nernst equation for fuel electrode's reaction H 2 O/H 2 or CO 2 /CO. An oxygen partial pressure model refers to the use of Nernst referring to oxygen partial pressure difference across the cell. A Mixed Potential model refers to the phenomena described by Fleming et al. as the Mixed Potential Theory (MPT), i.e. the observable Potential difference is the superposition of all above Potential differences. We conclude that the oxygen partial pressure model suffices for modern cells operated at temperature above 800 °C and if the concentration of CO 2 in the gas mixture is below 25%. Above this limit, MPT model is more accurate and thus recommended. The standard model exhibit large error in all cases and is not recommended. We also present the values of parameters, used in conjugation with MPT model, fitted to a cell with Ni-YSZ fuel electrode operated at 800 °C.