In order to improve the lightning protection performance of transmission lines, lightning protection management has been divided into every tower that lightning protection performance has been evaluated respectively. ...In order to improve the lightning protection performance of transmission lines, lightning protection management has been divided into every tower that lightning protection performance has been evaluated respectively. According to factors such as landform, span, tower type, grounding resistance, isolator type, and so on, relative ratio of tripping operation of every tower in the line has been calculated to evaluate its lightning protection safety performance, it is beneficial to operation maintenance and lightning reconstruction of transmission lines.展开更多
Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invent...Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invented the lightning rod in 1752,lightning rods have been used worldwide to prevent direct lightning strikes in various fields such as high-voltage power transmission lines,outdoor chemical sites,highways,land and sea wind farms,and forest lightning fire protection.It has been proven that lightning accidents still occur frequently in places where lightning rods are installed and the protective angle method is used.In order to further study the protective effect of lightning rods and identify the shortcomings of lightning rod protection,negative lightning strikes are taken as the research object,to analyze the limitations of lightning rods in preventing direct lightning strikes from the working principle of lightning rods.展开更多
The development of a computer program for evaluation of lightning safety distance between the tower and satellite dish is written in M-File MATLAB. The 3-dimensional illustrative graphics model is used to capture bett...The development of a computer program for evaluation of lightning safety distance between the tower and satellite dish is written in M-File MATLAB. The 3-dimensional illustrative graphics model is used to capture better understanding on how lightning protection system (LPS) works. The study of physical length of grounding electrode used on the tower is found to be significantly affecting the grounding system performances where they depend on magnitude of dispersed lightning strikes current and the settling time for the current to completely disperse. The grounding system performance is studied by using lightning impulse current (LIC) generator, simulated in OrCad PSpice software. It is found that the optimum length of vertical lightning rod in LPS is the same with the striking distance. There is no significant improvement is observed in lightning safety distance if the length of vertical lightning rod is higher than striking distance. The lightning strike peak current that has larger magnitude than the withstanding insulation level of specified object causes no physical damage. It is because the lightning safety distance increases when the lightning strike peak current becomes higher. It is also found that the lower grounding impedance generates higher magnitude of dispersed peak current and faster settling time.展开更多
Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth p...Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth place in the ten most lightning cities of the world, with a high keraunic level, which is 240 thunderstorm days per year, and in other words, a Ground Flash Density (GFD) of 48.3 flashes per square kilometer per year. In the power systems, high keraunic level would contribute to high possibility of power interruptions such as disruption, degradation, damage and downtime. These outages would ultimately lead to revenue losses and reduction of network reliability. These lightning related interruptions may be in terms of direct lightning strikes to the lines or to the equipments in the substation. By the use of Mat Lab GUI (Graphic Users Interface), this study presents a simple computer program which uses the electro-geometric model (EGM) for the designing of substation shielding systems. The EGM uses the concept where the protection zone of a lightning system lies within the radius where the upward channel initiates and propagates through the air terminal to meet the downward leader. This interception point is called “the point of discrimination” and is where the downward leader decides its final jump. The distance at which the last jump occurs is known as the striking distance. With the use of the striking distance and the mathematical equations developed by Young, Brown-Whitehead, IEEE-1992 (IEEE T&D Committee Equations) and IEEE-1995 (IEEE Substations Committee Equations). This project aimed to investigate, understand and analyse the substation protection by means of masts and shield wires. The analysis is extended to account for lightning protection provided by single mast to two masts as well as from single shield wire to double shielding wires. The outcomes of these four equations will be compared.展开更多
文摘In order to improve the lightning protection performance of transmission lines, lightning protection management has been divided into every tower that lightning protection performance has been evaluated respectively. According to factors such as landform, span, tower type, grounding resistance, isolator type, and so on, relative ratio of tripping operation of every tower in the line has been calculated to evaluate its lightning protection safety performance, it is beneficial to operation maintenance and lightning reconstruction of transmission lines.
基金Supported by Lightning Multi-pulse Intelligent Monitoring System Optimization Technology Project of Guangdong Yuedian Dianbai Hot Water Wind Farm(SFC/DBW-Z-FW-23-006).
文摘Since ancient times,lightning disasters have undoubtedly been an unstoppable threat to humanity.During thunderstorms,lightning often damages objects on the ground,such as buildings and structures.Since Franklin invented the lightning rod in 1752,lightning rods have been used worldwide to prevent direct lightning strikes in various fields such as high-voltage power transmission lines,outdoor chemical sites,highways,land and sea wind farms,and forest lightning fire protection.It has been proven that lightning accidents still occur frequently in places where lightning rods are installed and the protective angle method is used.In order to further study the protective effect of lightning rods and identify the shortcomings of lightning rod protection,negative lightning strikes are taken as the research object,to analyze the limitations of lightning rods in preventing direct lightning strikes from the working principle of lightning rods.
文摘The development of a computer program for evaluation of lightning safety distance between the tower and satellite dish is written in M-File MATLAB. The 3-dimensional illustrative graphics model is used to capture better understanding on how lightning protection system (LPS) works. The study of physical length of grounding electrode used on the tower is found to be significantly affecting the grounding system performances where they depend on magnitude of dispersed lightning strikes current and the settling time for the current to completely disperse. The grounding system performance is studied by using lightning impulse current (LIC) generator, simulated in OrCad PSpice software. It is found that the optimum length of vertical lightning rod in LPS is the same with the striking distance. There is no significant improvement is observed in lightning safety distance if the length of vertical lightning rod is higher than striking distance. The lightning strike peak current that has larger magnitude than the withstanding insulation level of specified object causes no physical damage. It is because the lightning safety distance increases when the lightning strike peak current becomes higher. It is also found that the lower grounding impedance generates higher magnitude of dispersed peak current and faster settling time.
文摘Malaysia is one of the many countries that experience high lightning related activities. In fact, according to Malaysian Meteorological Department the Ground Flash Density (GFD) in Malaysia, it is rated at the fifth place in the ten most lightning cities of the world, with a high keraunic level, which is 240 thunderstorm days per year, and in other words, a Ground Flash Density (GFD) of 48.3 flashes per square kilometer per year. In the power systems, high keraunic level would contribute to high possibility of power interruptions such as disruption, degradation, damage and downtime. These outages would ultimately lead to revenue losses and reduction of network reliability. These lightning related interruptions may be in terms of direct lightning strikes to the lines or to the equipments in the substation. By the use of Mat Lab GUI (Graphic Users Interface), this study presents a simple computer program which uses the electro-geometric model (EGM) for the designing of substation shielding systems. The EGM uses the concept where the protection zone of a lightning system lies within the radius where the upward channel initiates and propagates through the air terminal to meet the downward leader. This interception point is called “the point of discrimination” and is where the downward leader decides its final jump. The distance at which the last jump occurs is known as the striking distance. With the use of the striking distance and the mathematical equations developed by Young, Brown-Whitehead, IEEE-1992 (IEEE T&D Committee Equations) and IEEE-1995 (IEEE Substations Committee Equations). This project aimed to investigate, understand and analyse the substation protection by means of masts and shield wires. The analysis is extended to account for lightning protection provided by single mast to two masts as well as from single shield wire to double shielding wires. The outcomes of these four equations will be compared.
