High Voltage Electrical Substations Research Articles

Experimental study of the noise generated by urban high-voltage electrical substations

This work describes the results of sound pressure measurements carried out in the vicinity of ten high voltage electrical substations operating in areas of considerable urban density in the State of Rio de Janeiro. The work was motivated as a strategy to guide the proposition of an acoustic attenuation solution to meet the imposition of the Public Prosecutor's office, which interposed a civil action in the name of dissatisfied residents of the neighbourhood of one of the substations studied. Based on the acoustic limits imposed by the applicable environmental legislation, the study evaluated the acoustic noise level at different points in the neighbourhood of ten urban substations in the city of Rio de Janeiro, studying in depth the acoustic noise in the internal and external environments of the substation subject to the civil action brought. Although it is not possible to eliminate the acoustic noise generated by high voltage transformers since it results from the natural phenomenon of magnetostriction, which is intrinsic to the operation of any high-power electrical transformer, there are alternatives to mitigate the sound pressure level. As part of the strategy, the work recommends, as a first action, eliminating any tonal component associated with the acoustic noise, as its presence in the frequency spectrum causes discomfort to the human ear and penalizes measured levels by +5 dB. The work also shows that it is not trivial to discuss the impact of acoustic noise generated by substations installed in urban communities, whose acoustic noise commonly exceeds regulated limits. In conclusion, the work confirms that most electrical substations operate on the boundary line of the permissible noise limits.

THE EFFECT OF LIGHTNING ON HIGH VOLTAGE ELECTRICAL SUBSTATIONS’ LOW VOLTAGE SYSTEMS

The article presents the results of studies of the effects of lightning on low voltage systems of high voltage electrical substations with outdoor switchgears of 110 kV. The topicality of research is associated with a wide spreading of such substations as well as with a high reliability requirements of their work and, also, with their widespread distribution and high probability of lightning strikes to the substation or around it. The highest probable and the most dangerous effects of lightning on low voltage systems of a substation are determined on the basis of critical review and special literature analysis and, also, of systematization of practical information that had been collected during the survey of operating substations. Adequate physical models were developed for the list of hazardous effects based on physical processes of lightning. A model of each effect was studied on the basis of the sensitivity theory. The accuracy and adequacy of the models were verified by means of comparison of calculation results for the models under investigation with the results of calculations fulfilled in accordance with specialized programs, as well as from practical or theoretical data obtained by other authors. The factors that had been included in the models were studied and were defined in accordance with their nature (natural or artificial), the range of possible values in a substation was determined; the coefficients of elasticity were calculated. The obtained results enable to ascertain the contribution of the factor in the effect of lightning and the ability to control the factor. The relationship between the factors and the effects of lightning are shown as graphs. For practical application the information, obtained as the result of the research, was organized in the form of checklists that can be applied when collecting baseline information to develop the lightning protection of the substation, to examine the existing lightning protection, to investigate emergency situations associated with lightning strikes. The results of the study were used in practice during the pre-design survey of substations, development of the design assignment, design of lightning protection of a substation, and during fulfillment of acceptance tests and periodic inspections of lightning protection.

A Wireless System for Monitoring Leakage Current in Electrical Substation Equipment

In this paper, the design and the development of a remote system for continuous monitoring of leakage currents and ground currents in high voltage electrical substations are proposed. Based on wireless local area network technology, the system can be used to monitor continuously a variety of plants within the substation and has low power consumption with inbuilt overvoltage protection. It consists of a transmitter module equipped with a data acquisition (DAQ) system connected to leakage current and voltage sensors, and a receiver module connected to a remote controller for data processing and storage. The principle of operation and the characteristics of the various components of the system are described. Validation tests have been used to verify its performance in three different test situations: A) laboratory monitoring of the leakage current and voltage of a distribution surge arrester; B) laboratory measurement of the leakage current of an outdoor insulator; and C) field monitoring of the earth current and potential rise of high-voltage tower. The measured results are in close agreement with those recorded directly through a DAQ card with fiber-optic and coaxial cable connected systems. Data processing is carried out at the receiving end so that the monitored parameter is displayed continuously or at specified time intervals. The operation of the system has been tested and proved resilient under high-frequency interference signals such as those generated by corona and surface discharges.

Measurement and Modeling of Personal Exposure to the Electric and Magnetic Fields in the Vicinity of High Voltage Power Lines.

BackgroundThis work presents an experimental and modeling study of the electromagnetic environment in the vicinity of a high voltage substation located in eastern Algeria (Annaba city) specified with a very high population density. The effects of electromagnetic fields emanating from the coupled multi-lines high voltage power systems (MLHV) on the health of the workers and people living in proximity of substations has been analyzed.MethodsExperimental Measurements for the Multi-lines power system proposed have been conducted in the free space under the high voltage lines. Field's intensities were measured using a referenced and calibrated electromagnetic field meter PMM8053B for the levels 0 m, 1 m, 1.5 m and 1.8 m witch present the sensitive's parts as organs and major functions (head, heart, pelvis and feet) of the human body.ResultsThe measurement results were validated by numerical simulation using the finite element method and these results are compared with the limit values of the international standards.ConclusionWe project to set own national standards for exposure to electromagnetic fields, in order to achieve a regional database that will be at the disposal of partners concerned to ensure safety of people and mainly workers inside high voltage electrical substations.

An Investigation on Seismic Behavior of Three Interconnected Pieces of Substation Equipment

High-voltage electrical substations are used to distribute power between residential, industrial, commercial, and agricultural regions. Previous earthquakes have shown that electrical substations are seismically vulnerable. Although equipment of these substations had been designed individually according to the electrical and seismic requirements, they have shown poor seismic performance resulting from interaction problems. In recent decades, some research has been done on the effects of interaction between substation equipment items, which are connected by flexible or rigid conductors. Although more than two items are usually connected to each other, only two items are assumed in most studies. In this paper, the effects of interaction between three interconnected items are investigated using incremental dynamic analyses. Two failure modes are considered, including failure of insulators and disconnection of conductors. The results are presented in terms of maximum sustainable ground motion acceleration and failure probability, and discussions are made to choose the best pair of interconnected items.

Policy Development, Monitoring and Subject Reintroduction of Nonionising Radiation in Universiti Kebangsaan Malaysia

The effect of non-ionising radiation to human health has been a great concern. In the case of Universiti Kebangsaan Malaysia, this apprehension is especially significant, since it concerns students and university staff who study, work and live in the university compound. This worry is further justified with the existence of several Mobile Telephone Base Stations (MTBS), television and radio broadcast towers, high-voltage electric cables and electrical substations which are known to be sources of electromagnetic fields ranging from the Extremely Low Frequency (ELF) to the Radiofrequency (RF) range. This creates a serious quandary, since there are no safety guidelines focusing on limiting the non-ionizing radiation exposure dose to students and staff members. The objectives of this study are two-fold: 1) to monitor the non-ionising radiation level at various locations within the university compound to provide current data compared with exposure limits suggested by the Malaysian Communications and Multimedia Commission (MCMC) and International Non-Ionizing Radiation Committee (INIRC) of the International Radiation Protection Association (IRPA)and 2) to develop a non-ionising radiation policy for Universiti Kebangsaan Malaysia (UKM) from both the administrative and technical aspects. Six locations were chosen for monitoring based on the presence of radiation sources and/or student/staff occupancy, determined with the assistance of the Office of Occupational Safety and Health, Universiti Kebangsaan Malaysia. Three of these locations contain sources which emit radiation in the ELF range, while the remaining three emit RF radiation. Results showed that the ratio percentage between the RF and ELF exposures at these locations, in comparison to the MCMC and IRPA/INIRC exposure limits,were 0.2% and 2.8%, respectively. These results showed that for the time being, the exposures at all identified non-ionising radiation hotspots does not exceed the exposure limit suggested by both MCMC (which adopts the recommendation of ICNIRP, 1998) and IRPA/INIRC. However, a non-ionising radiation policy for UKM is still imperative, to serve as a reference and guideline for future activities that may contribute to the non-ionising radiation capacity. Subsequently, concerns were raised during the monitoring activities, especially amongst students who highlighted the necessity of a subject that introduces non-ionising radiation and its possible biological risk, as was offered by the Nuclear Science Department, before the restructuring of the Faculty of Physics and Applied Science in 2001.