Comparative Study on Substation Shielding Due to Direct Lightning Strokes

Abstract

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.

Fractal‐based lightning model for shielding failure rate calculation of transmission lines

“…Direct lightning stroke to the transmission lines and high-voltage substations, as two vital components of power systems, are the main causes of interruptions in power delivery [1][2][3]. Therefore, considering shielding system against direct lightning strokes is a key factor in designing these two important parts of the power systems.…”

Designing an Optimal Lightning Protection Scheme for Substations Using Shielding Wires

“…Each of the aforementioned methods for shielding a substation has its own advantages and disadvantages. However, the application of shielding wires is much more recommended due to its wide range of protection area [9].…”

Determination of the probability of a lightning strike in the elements of the object taking into account the statistical distribution of the current value

“…It is clear that class I requires the highest level of protection, so the radius of the sphere is defined as the smallest (equal to 20 m). Examples of the application of this approach are presented in [6][7][8][9][10][11]. It is noted that the calculated zones differ from the zones determined by the protective angle method.…”