Photovoltaic Power Plants as a Source of Electromagnetic Interference to Metallic Agricultural Pipelines

AbstractThe electromagnetic interference of power lines to nearby metallic pipelines has been a subject of research for many decades. Usually attention was given to gas or oil pipelines that shared the same rights-off-way with a power line for large distances. However, the recent advancement of renewable energy sources and specifically Photovoltaic (PV) power, due to generous incentives provided in many countries, has resulted in installations of large PV power stations even in agricultural areas. This brought up cases where such power stations in the MWp level, typically connected in medium voltage through buried cables, are located in the vicinity of metallic irrigation pipelines. Under certain conditions, these situations may result in induced voltages and currents on the pipeline that can pose threats to operating personnel. This work presents an analysis of the problems through a quasi-real case study adapted from a real case of a PV power station. The calculation methodology involves a hybrid method that is used in a way to reduced computational time. Results are presented both for normal operating conditions and faults in the power station and may be useful for both agriculture professionals and engineers

A comprehensive review: Evaluation of AC Induced Voltage on Buried Pipeline Near Overhead Transmission Lines and Mitigation Techniques Comparison

Steel pipelines used to transport gas and other petroleum products are protected by insulating coatings as well as cathodic protection systems. These pipelines sometimes are passed near the power lines, causing induced AC voltage on them. Increasing the AC voltage amplitude on the buried pipelines will increase the risk of electric shock, electric sparking between the equipment connected to the pipeline and the ground or adjacent metal structures, increasing the rate of insulation damage to the pipelines, disrupting the functioning of the cathodic protection system as well as increasing the AC corrosion of pipelines. Therefore, it is necessary to study and evaluate the factors affecting the inductive AC voltage level and provide effective solutions to reduce its destructive effects. In this paper, the inductive voltage of overhead lines on buried metal pipeline has been investigated under normal conditions of power system. The amount of induced voltage on the pipelines depends on some factors such as the current of the transmission line, the number of transmission line circuits, the arrangement of the phases, and the distance between the transmission line and the underground pipeline

Aircraft electromagnetic compatibility

Illustrated are aircraft architecture, electromagnetic interference environments, electromagnetic compatibility protection techniques, program specifications, tasks, and verification and validation procedures. The environment of 400 Hz power, electrical transients, and radio frequency fields are portrayed and related to thresholds of avionics electronics. Five layers of protection for avionics are defined. Recognition is given to some present day electromagnetic compatibility weaknesses and issues which serve to reemphasize the importance of EMC verification of equipment and parts, and their ultimate EMC validation on the aircraft. Proven standards of grounding, bonding, shielding, wiring, and packaging are laid out to help provide a foundation for a comprehensive approach to successful future aircraft design and an understanding of cost effective EMC in an aircraft setting

Arrangement of Phases of Double-circuit Three-phase Overhead Power Lines and Its Influence on Buried Parallel Equipment

This paper deals with electromagnetic fieldsaround double-circuit three-phase overhead power lines andtheir interference effects on the buried parallel equipment,such as pipelines or cables. The paper provides both ananalysis of electric and magnetic fields around doublecircuitpower transmission lines and

Grounding Performance under Lightning Surges in High Voltage Substations

Postponed access: the file will be accessible after 2019-05-31To achieve electromagnetic compatibility (EMC) and sufficient protection against lighting transients in the power transmission system, understanding of the grounding system transient behavior becomes crucial when deviating from international design standards and recommendations. To consider design deviations the present work is focused towards developing a method of integrating simplified grounding system models in transmission systems and perform lightning transient analysis on both parts to evaluate a particular design case. Firstly, the grounding system models for substation grounding grids, with a variety of configurations and sizes, is implemented. The characteristic transient response of the grounding system is visualized through simulations to study the sensitivity of configurations and modified soil parameters during current injections. The method of implementation allows for a detailed view and pre-processing of large data-sets from simulations. The advantages of this method is used to extract overall measured values to create a tool for EMC analysis and in addition processing different parameters and functions of the grounding system. Secondly, the grounding system model is integrated into transmission systems using a newly released interfacing application. The application allows for co-simulation between the development software of the grounding system and a specialized tool for the transmission system. The innovation of this modeling approach is given as a contribution to an international conference by submitting a paper. Finally, the integrated grounding models and transmission system are studied with two substation design cases; a short and long cable between surge arrester and transformer. The short cable case follows well-known design standards where the long cable case is a design deviation which is common in larger domestic hydropower plants. Even though the long cable case is deviating from design recommendations, the results show a less negative impact on the grounding system compared to the short cable case.Masteroppgave i energiMAMN-ENERGENERGI39

Current Step Generation and Measurement with Rise-time in the Range of Nanoseconds

A current step generator based on a charged coaxial cable is designed and tested for characterizing impulse current shunts. This thesis has developed a traceable calibration infrastructure for fast shunts and other current sensors, defined measurement techniques for a current step and improved the test procedure and measurement capabilities. For calibration of shunts, current coil sensors are used in the measurement circuits. Since no calibration services are currently available for impulse current measuring systems, a best circuit combination is proposed for current step generation with a rise time of less than 5 ns, along with a proposed reference shunt that aims to provide the best and most stable measurement results with negligible noise, oscillations, and droop in the measured current step. Based on techniques found in the literature, current steps are generated, and different sensors were used to measure the generated steep front current steps. The generation system consists of a 110-m long, 50-Ω coaxial cable and a spark gap. Various spark gap switches, including the SF6 spark gap, are used for generating current steps. With the coaxial cable charged from one end, a current step is generated after reflecting back from the open end with a step length of twice the cable transmission delay. The cable is than discharged to the shunt (or coil) through the spark gap. The measurement system consists of shunts and coil current sensors, 5:1 and 6.6:1 attenuators based on the requirement of the sensors. The recording instrument is a 1-GHz, 8-bit, 1-GS/s digitizer. The proposed step generator can produce current steps with a stable current of up to 100 A. The rise time of the step varies from 1.6 ns to 15 ns, depending on the spark gap used for switching. The produced current is constant within 0.5% for a step length of 960 ns generated with a coaxial cable 110 m in length. To improve the test procedure and measurement capabilities, the thesis also analyzed factors affecting current step measurement, such as the type of coaxial cable, type of connection, extra shielding, clearances, interference sources, media of the spark gap, and the spark gap electrode distance (arc length). It is found that the measurement system and the rise time of current step is affected by many factors, including the coaxiality of the connection, impedance mismatch, interference, clearances, stray capacitances, and stray inductances. These results will enable future standardization of impulse current sensors

Avionics system design for high energy fields: A guide for the designer and airworthiness specialist

Because of the significant differences in transient susceptibility, the use of digital electronics in flight critical systems, and the reduced shielding effects of composite materials, there is a definite need to define pracitices which will minimize electromagnetic susceptibility, to investigate the operational environment, and to develop appropriate testing methods for flight critical systems. The design practices which will lead to reduced electromagnetic susceptibility of avionics systems in high energy fields is described. The levels of emission that can be anticipated from generic digital devices. It is assumed that as data processing equipment becomes an ever larger part of the avionics package, the construction methods of the data processing industry will increasingly carry over into aircraft. In Appendix 1 tentative revisions to RTCA DO-160B, Environmental Conditions and Test Procedures for Airborne Equipment, are presented. These revisions are intended to safeguard flight critical systems from the effects of high energy electromagnetic fields. A very extensive and useful bibliography on both electromagnetic compatibility and avionics issues is included

Electric return current distribution through train wagons in AC railway systems

RESEARCH DISSERTATION School of Electrical and Information Engineering University of the Witwatersrand, JohannesburgThe electric railway environment has long been considered electromagnetically unfriendly and has been plagued by electromagnetic interference. Recently, it has been found that a substantial percentage of return current flows through the couplers of moving trains. This current has been the cause of electromagnetic interference in neighbouring systems and the electrical erosion of wagon bearings. This document provides a brief background around the observed current in the wagon couplers of electric trains as well as the effects thereof. Information from railway experts is presented in the form of a literature survey in order to establish a high level understanding of electric railway configurations and the challenges that have been experienced with the various configurations. The document goes on to establish a theoretical background of the concepts expanded upon in the development of a system model. Some theoretical discussion included is the concept of power factors, basic magnetic circuits, internal inductance, the proximity effect, mutual-inductance, the dot convention and multi-conductor transmission lines. Once the theoretical background is established, the development of a system model is proposed and presented. The model that is proposed considers the supply infrastructure configuration, locomotive or locomotive consist and a single wagon which is cascaded to form a train. This model is the culmination of the research. Following the system model development, the model was tested against measured data both from Sweden (external) and South Africa (internal) to give confidence in the model. The model was used to perform investigations of various conditions on the current distribution in a train. Some interesting observations that were made include the uneven distribution of current exiting the axles of a wagon, as well as the idea that higher frequency components of the return current will tend to travel in the couplers of the train, whilst lower frequency components will tend to travel through the electrical supply infrastructure such as the rails.M T 201