Electrical safety against electric shock is the process of minimization of the risk of damage to ... more Electrical safety against electric shock is the process of minimization of the risk of damage to persons through specific protective measures. Safety can be increased by effectively separating persons from energized parts (i.e. protection against direct contact), and by limiting the exposure time to touch voltages in case of failure of electrical equipment (i.e. protection against indirect contact). Is it possible to calculate Safety? Is there a way to predict the level of risk to persons as offered by standard protective measures against electric shock? And even more importantly, what is the level of safety which we can deem as "acceptable"? This paper seeks to respond to these questions by defining, and quantitatively analyzing, both the Safety of different standard protective measures against direct and indirect electric contact, and their related risk exposure, as typically employed in both industrial and commercial power systems.
IEEE Transactions on Industry Applications, Jul 1, 2010
ABSTRACT Antennas, if present on roofs, are, usually, the most prominent part of edifices. Ground... more ABSTRACT Antennas, if present on roofs, are, usually, the most prominent part of edifices. Grounding their metal supports is, generally, considered an effective means of protection of the structure against the effects of lightning strokes, eventually “attracted” by the antennas themselves. The antenna's mast and the down conductor are incorrectly assumed capable of safely draining to ground the lightning current flowing at the point of strike. This, supposedly, would prevent both hazard for people and damage to the building and electrical equipment situated inside of it. This paper will substantiate how the sole grounding of the antenna's mast can instead result in lowering the safety of the edifice, and, thereby, expose users to the hazard of dangerous electrical sparking (flashover) and possible fires.
Load modeling remains a challenging task in planning, operation and control of power grids. In th... more Load modeling remains a challenging task in planning, operation and control of power grids. In this paper, a support vector machine (SVM) based machine learning method is proposed for dynamic load modeling of large scale power systems using synchrophasor data recorded by Phasor Measurement Units (PMUs). The difference equation based dynamic load model structure is recommended, however, if a traditional transfer function based model format is preferred, it can be directly obtained from difference equation based model. Case studies are conducted using PMU data recorded in a large power grid in North America. The accuracy of the developed load models is verified by comparing the simulated load model dynamic response with real PMU data. The proposed method not only provides an accurate dynamic load model, parameters of the load model can also be easily updated using new synchrophasor data for either on-line or off-line applications.
As a new emerging approach, virtual synchronous generator (VSG) control for interfacing inverters... more As a new emerging approach, virtual synchronous generator (VSG) control for interfacing inverters in renewable distributed generation (DG)-based microgrids has attracted significant research interest. However, VSG control cannot ensure proportional reactive power sharing among DG units when unequal transmission line impedances are involved, although active power sharing remains proportional among DGs. In this article, an adaptive virtual impedance-based VSG control approach for grid-connected and islanded microgrids is proposed to alleviate impedance difference at the inverter output and improve proportional reactive power sharing among DGs. The virtual impedance consists of an adaptive virtual resistance and a fixed virtual inductance, where the virtual resistance is designed adaptively based on operation points of the microgrid. In this article, the proposed adaptive virtual impedance control is implemented on a modified VSG control, known as fuzzy secondary controller-based VSG control, offering excellent voltage and frequency regulation at the PCC. Its performance is demonstrated through case and sensitivity studies using MATLAB/Simulink simulation; and further validated by comparing with an existing method.
IEEE Transactions on Industry Applications, Sep 1, 2008
Bonding plays a crucial role in maintaining continuity of the equipment grounding path. A clear p... more Bonding plays a crucial role in maintaining continuity of the equipment grounding path. A clear path to ground allows a prompt response of the protective devices, located upstream of the fault. Protective bonding conductors are called for by the international electrotechnical commission (IEC) Standards as a specific safety requirement. Through the years, we have been assisting in the proliferation of
ABSTRACT This paper describes safety and risk analysis of standard protective measures against el... more ABSTRACT This paper describes safety and risk analysis of standard protective measures against electric shock.
Electrical safety against electric shock is the process of minimization of the risk of damage to ... more Electrical safety against electric shock is the process of minimization of the risk of damage to persons through specific protective measures. Safety can be increased by effectively separating persons from energized parts (i.e. protection against direct contact), and by limiting the exposure time to touch voltages in case of failure of electrical equipment (i.e. protection against indirect contact). Is it possible to calculate Safety? Is there a way to predict the level of risk to persons as offered by standard protective measures against electric shock? And even more importantly, what is the level of safety which we can deem as "acceptable"? This paper seeks to respond to these questions by defining, and quantitatively analyzing, both the Safety of different standard protective measures against direct and indirect electric contact, and their related risk exposure, as typically employed in both industrial and commercial power systems.
IEEE Transactions on Industry Applications, Jul 1, 2010
ABSTRACT Antennas, if present on roofs, are, usually, the most prominent part of edifices. Ground... more ABSTRACT Antennas, if present on roofs, are, usually, the most prominent part of edifices. Grounding their metal supports is, generally, considered an effective means of protection of the structure against the effects of lightning strokes, eventually “attracted” by the antennas themselves. The antenna's mast and the down conductor are incorrectly assumed capable of safely draining to ground the lightning current flowing at the point of strike. This, supposedly, would prevent both hazard for people and damage to the building and electrical equipment situated inside of it. This paper will substantiate how the sole grounding of the antenna's mast can instead result in lowering the safety of the edifice, and, thereby, expose users to the hazard of dangerous electrical sparking (flashover) and possible fires.
Load modeling remains a challenging task in planning, operation and control of power grids. In th... more Load modeling remains a challenging task in planning, operation and control of power grids. In this paper, a support vector machine (SVM) based machine learning method is proposed for dynamic load modeling of large scale power systems using synchrophasor data recorded by Phasor Measurement Units (PMUs). The difference equation based dynamic load model structure is recommended, however, if a traditional transfer function based model format is preferred, it can be directly obtained from difference equation based model. Case studies are conducted using PMU data recorded in a large power grid in North America. The accuracy of the developed load models is verified by comparing the simulated load model dynamic response with real PMU data. The proposed method not only provides an accurate dynamic load model, parameters of the load model can also be easily updated using new synchrophasor data for either on-line or off-line applications.
As a new emerging approach, virtual synchronous generator (VSG) control for interfacing inverters... more As a new emerging approach, virtual synchronous generator (VSG) control for interfacing inverters in renewable distributed generation (DG)-based microgrids has attracted significant research interest. However, VSG control cannot ensure proportional reactive power sharing among DG units when unequal transmission line impedances are involved, although active power sharing remains proportional among DGs. In this article, an adaptive virtual impedance-based VSG control approach for grid-connected and islanded microgrids is proposed to alleviate impedance difference at the inverter output and improve proportional reactive power sharing among DGs. The virtual impedance consists of an adaptive virtual resistance and a fixed virtual inductance, where the virtual resistance is designed adaptively based on operation points of the microgrid. In this article, the proposed adaptive virtual impedance control is implemented on a modified VSG control, known as fuzzy secondary controller-based VSG control, offering excellent voltage and frequency regulation at the PCC. Its performance is demonstrated through case and sensitivity studies using MATLAB/Simulink simulation; and further validated by comparing with an existing method.
IEEE Transactions on Industry Applications, Sep 1, 2008
Bonding plays a crucial role in maintaining continuity of the equipment grounding path. A clear p... more Bonding plays a crucial role in maintaining continuity of the equipment grounding path. A clear path to ground allows a prompt response of the protective devices, located upstream of the fault. Protective bonding conductors are called for by the international electrotechnical commission (IEC) Standards as a specific safety requirement. Through the years, we have been assisting in the proliferation of
ABSTRACT This paper describes safety and risk analysis of standard protective measures against el... more ABSTRACT This paper describes safety and risk analysis of standard protective measures against electric shock.
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Papers by Massimo Mitolo