Comparison of the lightning performance between the poles of the Cahora-Bassa ±533 kV HVDC lines

This work contributes toward research in the field of lightning performance of High Voltage Direct Current (HVDC) transmission lines, focusing on the impact of the line polarity on the incidence of line faults. Although there has been some recent research into the influence of polarity, there appears to be no confirmed effect that might influence the design of new lines. The research presents an investigation into the lightning performance of the two poles of the Cahora-Bassa HVDC transmission line. In order to compare the performance of the two polarities, the average lightning exposure over an 8-year period was confirmed to be very similar for both lines. Lightning stroke data from the South African Lightning Detection Network was correlated with fault times from the transmission-line protection scheme. The classification of the lightning related faults was used to determine the relative performance of the two poles, particularly in relation to polarity, and to infer if there was any influence of polarity on the lightning attachment process. This investigation for the Cahora-Bassa scheme shows that twenty-three out of twenty-five lightning related faults occurred on the positive pole. The results concur with performance experience on several HVDC lines from China and Canada, which indicate that lightning related faults favour the positive pole by a ratio of between 8:1 and 10:1. This represents a valuable contribution, which substantiates that HVDC line polarity has an influence on the lightning attachment process, and indicates that there is a need to re-examine the lightning shielding design for HVDC transmission lines.GS201

Energy Conversion Alternatives Study (ECAS), General Electric Phase 1. Volume 2: Advanced energy conversion systems. Part 3: Direct energy conversion cycles

For abstract, see N76-23680

Stability, Transient Response, Control, and Safety of a High-Power Electric Grid for Turboelectric Propulsion of Aircraft

This document contains the deliverables for the NASA Research and Technology for Aerospace Propulsion Systems (RTAPS) regarding the stability, transient response, control, and safety study for a high power cryogenic turboelectric distributed propulsion (TeDP) system. The objective of this research effort is to enumerate, characterize, and evaluate the critical issues facing the development of the N3-X concept aircraft. This includes the proposal of electrical grid architecture concepts and an evaluation of any needs for energy storage

Assessment of the electrical performance of the Cahora Bassa HVDC scheme.

Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.The aim of this study was to assess the electrical performance of the Cahora Bassa HVDC scheme. For practical reasons a database was developed to hold and analyse the performance data. Microsoft® Access 2002 relational database management system was chosen for this work. The principle of simplicity and flexibility were used in the design of the database. The Apollo year 2002 faults data was populated into the database. The database stored the information in a format that enables the user to extract results and the information required by Ciqre, The Ciqre Working Group 14 collects performance information from all the participating HVDC schemes around the world annually. The Apollo converter station's 2002 performance data was compared to other similar HVDC schemes that submitted to Cigre in the year 2002. In addition performance trends were drawn from similar schemes that submitted to Cigre over the past years. The Apollo performance data is quite comparable to other similar schemes in 2002 and over the past years

The state-of-the-art of dc power distribution systems/components for space applications

This report is a survey of the state of the art of high voltage dc systems and components. This information can be used for consideration of an alternative secondary distribution (120 Vdc) system for the Space Station. All HVdc components have been prototyped or developed for terrestrial, aircraft, and spacecraft applications, and are applicable for general space application with appropriate modification and qualification. HVdc systems offer a safe, reliable, low mass, high efficiency and low EMI alternative for Space Station secondary distribution

Power system applications of fiber optics

Power system applications of optical systems, primarily using fiber optics, are reviewed. The first section reviews fibers as components of communication systems. The second section deals with fiber sensors for power systems, reviewing the many ways light sources and fibers can be combined to make measurements. Methods of measuring electric field gradient are discussed. Optical data processing is the subject of the third section, which begins by reviewing some widely different examples and concludes by outlining some potential applications in power systems: fault location in transformers, optical switching for light fired thyristors and fault detection based on the inherent symmetry of most power apparatus. The fourth and final section is concerned with using optical fibers to transmit power to electric equipment in a high voltage situation, potentially replacing expensive high voltage low power transformers. JPL has designed small photodiodes specifically for this purpose, and fabricated and tested several samples. This work is described

Summary Report Comparing High Voltage Overhead and Underground Transmission Infrastructure

This report summarises the findings of an independent systematic literature review of high voltage overhead and underground transmission infrastructure, which was undertaken by The University of Queensland and Curtin University. This is the summary report for the study which is complemented by more detailed reports provided separately in Chapters 1 to 8 which cover the themes and cases studies in more detail

Modelling of a protective scheme for AC 330 kV transmission line in Nigeria

Transmission lines play a vital role in the reliable and efficient delivery of electrical power over long distances, and these lines are affected by faults that occur due to lightning strikes, equipment failures, human, animal or vegetation interference, environmental factors, ageing equipment, voltage sag or grid faults adverse effects on the line. Therefore, protecting these transmission lines becomes crucial with the increasing demand for electricity and the need to ensure grid stability. The modelling process involves the development of a comprehensive protection scheme utilising modern technologies and advanced algorithms. The protection scheme encompasses various elements, including fault detection, fault classification, fault location, and fault clearance. It incorporates intelligent devices, such as protective relays and communication systems, to enable rapid and accurate fault identification and isolation. First, a 330 kV, 500 km three-phase Delta transmission line is modelled using MATLAB/SIMULINK. A section of the Delta network in Delta State Nigeria was used since the entire Nigeria 330 kV network is large. Faulty current and voltage data were generated for training using the CatBoost, 93340 data sizes comprising fault data from three-phase current and voltage extracted from the Delta transmission line model in Nigeria were designed, and twelve fault conditions were used. The CatBoost classifier was employed to classify the faults after different machine language algorithm was used to train the same data with other parameters. The trainer achieved the best accuracy of 99.54%, with an error of 0.46%, at 748 iterations out of 1000 compared to GBoost, XBoost and other classification techniques. Second, the Artificial Neural Network technique was used to train this data, and an accuracy of 100% was attained for fault detection and about 99.5% for fault localisation at different distances with 0.0017 microseconds of detection and an average error of 0% to 0.5%. This model performs better than Support Vector Machine and Principal Component Analysis with a higher fault detection time. The effect of noise signal on the ANN model was studied, and the discrete wavelet technique was used to de-noise the signal for better performance and to enhance the model’s accuracy during transient. Third, the wavelet transforms as a data extraction model to detect the threshold value of current and voltage and the coordination time for the backup relay to trip if the primary relay does not operate or clear the fault on time. The difference between the proposed model and the model without the threshold value was analysed. The simulated result shows that the trip time of the two relays demonstrates a fast and precise trip time of 60% to 99.87% compared to other techniques used without the threshold values. The proposed model can eliminate the trial-and-error in programming the instantaneous overcurrent relay setting for optimal performance. Fourth, the PSO-PID controller algorithm was used to moderate the load frequency of the transmission network. Due to the instability between the generation and distribution, there is always a switch in the stability of the transmission or load frequency; therefore, the PSO-PID algorithm was used to stabilise the Delta power station as a pilot survey from the Nigerian transmission network. Also, a hybrid system with five types of generation and two load centres was used in this model. It has been shown that the proposed control algorithm is effective and improves system performance significantly. As a result, the suggested PSO-PID controller is recommended for producing high-quality, dependable electricity. Moreover, the PSO-PID algorithm produces 0.00 seconds settling time and 0.0005757 ITAE. It’s essential to carefully consider potential drawbacks like complexity and computational overhead, sensitivity to algorithm parameters, potential parameter convergence and limited interpretability and assess their impact on the specific LFC application before implementing a PSO-PID controller in a power system. When implemented with the model in this research, the Delta transmission line network will reduce the excessive fault that occurs in the transmission line and improve the energy efficiency of the entire network when replicated with the Nigerian network. Generally, for the effective design and implementation of the protection scheme of the 330 kV transmission line, the fault must be detected and classified, and the exact location of the fault must be ascertained before the relay protection and load frequency control will be applied for effective fault management and control system