CN Tower Lightning Flash Characteristics Based on Recorded Currents and Trajectory Images

2020 Research Internship Project

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Faculty Name

Ali Hussein

Project Title

CN Tower Lightning Flash Characteristics Based on Recorded Currents and Trajectory Images

Project Description

In order to study the characteristics of tall-structure lightning, the exact location of lightning strikes must be known. This can be accomplished using instrumented tall structures or rockets trailing conducting wires. The existent of the 553-m CN Tower in Toronto has generated wealth of information about tall-structure lightning since 1978; two years after its construction. While the detailed process of tall-structure lightning is different from lightning to short objects or flat ground, observations of lightning to tall structures have generated wealth of information about the lightning phenomena in general and facilitated the development of lightning return-stroke models, which have contributed to solving the important inverse-source problem, where the lightning current is estimated based on the commonly measured lightning-generated electromagnetic pulse (LEMP). Instrumented tall structures are also important tools for the evaluation of the performance characteristics of lightning detection network. Although several years ago, the CN Tower ceased to be the tallest manmade freestanding structure in the world, it is still the world’s tallest tower that is fully instrumented for lightning measurements and it remains the applicant’s greatest research capital and advantage. In 1991, five independent measurement systems simultaneously operated to record: 1. The lightning current at the tower using a 40MHz Rogowski coil connected to a Tektronix RTD 710A digitizer via a triaxial cable. 2. The associated LEMP, placed 2km north of the tower, using broadband electric and magnetic field sensors connected to two RTD 710A digitizers. 3. Lightning return-stroke velocity using a photodiode system. 4. The lightning channel trajectory using two VHS cameras. Expansions of CNT lightning measurement capabilities have since continued. In 1996, a Phantom v2 digital optical imaging system (1000 images/s) was acquired (NSERC Equipment Grant, $87,719.00). It was upgraded in 2006 with Phantom v5. In 1997, a second Rogowski coil and an optical fibre link were acquired for recording the derivative of the lightning current. In 1999, two LeCroy LT342L digitizers were obtained for recording the lightning current-derivative impulses and their associated LEMPs. In 2001, four Global Positioning Systems were added for time synchronization of recording instruments. In 2008, a National Instrument (NI) PCI5114 digitizer with extended memory, for the continuous recording of all flash current components, was acquired. In 2015, a $37,000 NI PXI Data Acquisition System was acquired for the continuous recording of the lightning current with 1-ns resolution. A major objective of observing lightning strikes to the CNT is to derive statistics regarding tall-structure lightning parameters, which is to assist in the establishment of more sophisticated lightning protection procedures, especially at tall structures, such as wind turbines. This research focuses on the statistical analysis of CNT lightning flash characteristics based on the simultaneously recorded data (flash components, flash time duration, inter-stroke time duration between successive return strokes, the number of strokes/flash and the continuing current duration/flash. The lightning current peak and its maximum rate of rise are also of interest to lightning protection procedures. Because of the large amount of data, the statistical analysis of lightning flash characteristics is fundamental to researchers working in the area of protection and to international organizations developing standards related to lightning, such as Conseil International des Grands Reseaux Electriques (CIGRE) working group C4.410 “Lightning Striking Characteristics for Very High Structures.” It is worth mentioning that due to the applicant’s limited research funding, as well as his funding responsibility towards graduate students, he will not be able to fully pay the needed research assistant during the upcoming lightning season (May-August, 2020). Therefore, this application is important to the applicant in order to achieve the needed personnel for the analysis of the available and future extensive CNT lightning data.

Student Responsibility

The student taking this research internship position is to participate in the operation and programming of the state-of-the-art lightning measurement systems. The duties include the active participation in the lightning current data acquisition and the recorded trajectories using the high-speed imaging systems during the 2020 lightning season (May-August), as well as the processing and analysis of acquired and future lightning data for the eventual goal of deriving statistics concerning the characteristics of flash components. In addition to the applicant’s direct supervision, the student will interact with the applicant's graduate students (presently: 2 PhD’s). The applicant schedules meetings with his research team, especially during the lightning season, in which everyone present a progress report concerning his/her achievements/difficulties. Thus, every member of the research team gains awareness of the work of others. Graduate and undergraduate research students are directed to submit their research accomplishments to relevant national/international conferences. It is worth mentioning that the applicant has fully supervised eleven NSERC USRA students since the summer of 1998. Also, two full-time URO students, and nine full-time and eleven part-time research assistant undergraduate students were fully supervised by the applicant since 2004. He also fully supervised four undergraduate summer research internship students during the last 4 years. Since 2002, the applicant’s fully-supervised "undergraduate" students presented 13 papers at the International Conference on Upcoming Engineers (ICUE) and the Cage Club Student Conferences on High Voltage Engineering and Electrostatics.

Specific Requirements

This position requires a student, who has completed the third year of the Electrical Engineering program. Practical orientation and computer literacy are important. The applicant needs to provide a CV and transcripts.