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Papers by Kian Hoong Kwan

International Journal of Hydrogen Energy, 2009

In this paper, planar air breathing PEMFCs without the need for endplates are proposed for low po... more In this paper, planar air breathing PEMFCs without the need for endplates are proposed for low power portable applications. PEMFCs with 3 different cathode designs (parallel slit, circular open and oblique slit) with the same opening ratio and employing self-humidifying MEAs were investigated. Performance and stability tests were conducted in hydrogen dead-end operation under both self-breathing and forced convection condition. It was found that rib geometry and hydraulic diameter have significant impact on oxygen transportation. It was concluded that circular opening design yields the best performance and highest limiting current. This is because this design provides the shortest rib distance and smallest hydraulic diameter. However, fuel cell instability was observed under self-breathing and forced convection condition. This is due to the water accumulation that could not be removed by natural-evaporation at the opening cathode. Overall, our proposed air breathing PEMFC achieves a specific power of 150 W kg−1 and a power density of 347 mW cm−3.

This paper presents a model predictive control (MPC) design for the unified power quality conditi... more This paper presents a model predictive control (MPC) design for the unified power quality conditioner (UPQC), an integration of series and shunt active filters to improve power quality in a power distribution system. The control strategy aims to regulate the load voltage and the source current to the desired references in spite of the existence of harmonic components in the supply voltage and the load current, possible sag or swell in the supply voltage, and non-unity power factor of the supply side. Kalman filters are used to extract the fundamental as well as the harmonic components abovementioned, which will then be used to formulate the desired references and regarded as measurable disturbances, respectively. Based on a state-space model developed for the UPQC, an MPC controller is designed. Simulation studies on a single-phase power distribution system are also presented to verify the performance.

This paper employs the unified power quality conditioner (UPQC), an integration of series and shu... more This paper employs the unified power quality conditioner (UPQC), an integration of series and shunt active filters, to perform harmonic compensation and power factor correction. Selective harmonic compensation can be implemented too. In addition, the UPQC can be used to perform load sharing with the supply. The UPQC is controlled by the multi-variable regulator-based (MVR) UPQC with Kalman filters. This control design employs Kalman filters to extract the fundamental and the harmonic components of the supply voltage and the load current in a power distribution system. Kalman filter is also used to estimate the variables of the UPQC. Simulation results on a single-phase power distribution system are presented to verify the performance.

This paper reports the integration of a hybrid system that consist of a proton exchange membrane ... more This paper reports the integration of a hybrid system that consist of a proton exchange membrane fuel cell (PEMFC) and an ultra-capacitor (UC) with the UPQC. Apart from performing load sharing with the grid, the overall UPQC is able to handle a wide range of power quality (PQ) problems; thus enhancing the functions of the UPQC and ensures higher network availability, reliability and stability. The UPQC is controlled by the Model Predictive Control (MPC), which has the capability to handle hard constraints. Illustrative examples to demonstrate the robustness and performance of the UPQC with the hybrid system are presented. The proposed hybrid system is generic in nature and can be used with other UPQCs to enhance their performance and capabilities.

IEEE Transactions on Industrial Electronics, 2012

This paper proposes a novel control design for the unified power quality conditioner (UPQC). This... more This paper proposes a novel control design for the unified power quality conditioner (UPQC). This design, enabled by a control framework that employs the output regulation (OR) theory, is also made up of an exogenous Kalman filter used to extract the state components of the distorted supply voltage and load current, and a plant Kalman filter as a state observer.

In 2009, Singapore embarked on an Intelligent Energy System (IES) pilot project. The IES pilot wi... more In 2009, Singapore embarked on an Intelligent Energy System (IES) pilot project. The IES pilot will involve consumers in the residential, commercial and industrial locations, including the Nanyang Technological University (NTU) campus, the CleanTech Park at Jalan Bahar and the Punggol Eco-Precinct. This is an important step towards a smarter power grid, which will provide consumers with more information, choice and control over their electricity usage, thereby improving energy efficiency for Singapore as a whole.

IEEE Transactions on Industrial Electronics, 2009

IEEE Transactions on Industrial Electronics, 2009

This paper presents a solution to the control of a unified power quality (PQ) conditioner (UPQC) ... more This paper presents a solution to the control of a unified power quality (PQ) conditioner (UPQC) for PQ improvement in power distribution systems. The problem formulation allows not only harmonic compensation but also voltage sags/swells, load demand changes, and power factor correction to be tackled in a unified framework. The proposed controller combines the multivariable regulator theory with H infin loop shaping, so that zero steady-state error, robustness to modeling uncertainties, and insensitivity to supply frequency variations can be accomplished simultaneously, thus providing a complete theoretical solution to all the aforementioned PQ problems. The effectiveness of the proposed controller is, in practice, verified by experimental studies on a single-phase power distribution system.

International Journal of Hydrogen Energy, 2009

In this paper, planar air breathing PEMFCs without the need for endplates are proposed for low po... more In this paper, planar air breathing PEMFCs without the need for endplates are proposed for low power portable applications. PEMFCs with 3 different cathode designs (parallel slit, circular open and oblique slit) with the same opening ratio and employing self-humidifying MEAs were investigated. Performance and stability tests were conducted in hydrogen dead-end operation under both self-breathing and forced convection condition. It was found that rib geometry and hydraulic diameter have significant impact on oxygen transportation. It was concluded that circular opening design yields the best performance and highest limiting current. This is because this design provides the shortest rib distance and smallest hydraulic diameter. However, fuel cell instability was observed under self-breathing and forced convection condition. This is due to the water accumulation that could not be removed by natural-evaporation at the opening cathode. Overall, our proposed air breathing PEMFC achieves a specific power of 150 W kg−1 and a power density of 347 mW cm−3.

This paper presents a model predictive control (MPC) design for the unified power quality conditi... more This paper presents a model predictive control (MPC) design for the unified power quality conditioner (UPQC), an integration of series and shunt active filters to improve power quality in a power distribution system. The control strategy aims to regulate the load voltage and the source current to the desired references in spite of the existence of harmonic components in the supply voltage and the load current, possible sag or swell in the supply voltage, and non-unity power factor of the supply side. Kalman filters are used to extract the fundamental as well as the harmonic components abovementioned, which will then be used to formulate the desired references and regarded as measurable disturbances, respectively. Based on a state-space model developed for the UPQC, an MPC controller is designed. Simulation studies on a single-phase power distribution system are also presented to verify the performance.

This paper employs the unified power quality conditioner (UPQC), an integration of series and shu... more This paper employs the unified power quality conditioner (UPQC), an integration of series and shunt active filters, to perform harmonic compensation and power factor correction. Selective harmonic compensation can be implemented too. In addition, the UPQC can be used to perform load sharing with the supply. The UPQC is controlled by the multi-variable regulator-based (MVR) UPQC with Kalman filters. This control design employs Kalman filters to extract the fundamental and the harmonic components of the supply voltage and the load current in a power distribution system. Kalman filter is also used to estimate the variables of the UPQC. Simulation results on a single-phase power distribution system are presented to verify the performance.

This paper reports the integration of a hybrid system that consist of a proton exchange membrane ... more This paper reports the integration of a hybrid system that consist of a proton exchange membrane fuel cell (PEMFC) and an ultra-capacitor (UC) with the UPQC. Apart from performing load sharing with the grid, the overall UPQC is able to handle a wide range of power quality (PQ) problems; thus enhancing the functions of the UPQC and ensures higher network availability, reliability and stability. The UPQC is controlled by the Model Predictive Control (MPC), which has the capability to handle hard constraints. Illustrative examples to demonstrate the robustness and performance of the UPQC with the hybrid system are presented. The proposed hybrid system is generic in nature and can be used with other UPQCs to enhance their performance and capabilities.

IEEE Transactions on Industrial Electronics, 2012

This paper proposes a novel control design for the unified power quality conditioner (UPQC). This... more This paper proposes a novel control design for the unified power quality conditioner (UPQC). This design, enabled by a control framework that employs the output regulation (OR) theory, is also made up of an exogenous Kalman filter used to extract the state components of the distorted supply voltage and load current, and a plant Kalman filter as a state observer.

In 2009, Singapore embarked on an Intelligent Energy System (IES) pilot project. The IES pilot wi... more In 2009, Singapore embarked on an Intelligent Energy System (IES) pilot project. The IES pilot will involve consumers in the residential, commercial and industrial locations, including the Nanyang Technological University (NTU) campus, the CleanTech Park at Jalan Bahar and the Punggol Eco-Precinct. This is an important step towards a smarter power grid, which will provide consumers with more information, choice and control over their electricity usage, thereby improving energy efficiency for Singapore as a whole.

IEEE Transactions on Industrial Electronics, 2009

IEEE Transactions on Industrial Electronics, 2009

This paper presents a solution to the control of a unified power quality (PQ) conditioner (UPQC) ... more This paper presents a solution to the control of a unified power quality (PQ) conditioner (UPQC) for PQ improvement in power distribution systems. The problem formulation allows not only harmonic compensation but also voltage sags/swells, load demand changes, and power factor correction to be tackled in a unified framework. The proposed controller combines the multivariable regulator theory with H infin loop shaping, so that zero steady-state error, robustness to modeling uncertainties, and insensitivity to supply frequency variations can be accomplished simultaneously, thus providing a complete theoretical solution to all the aforementioned PQ problems. The effectiveness of the proposed controller is, in practice, verified by experimental studies on a single-phase power distribution system.