Modelling of Luminous Flux Directed to the Upper Hemisphere from Electrical Substation before and after the Refurbishment of Lighting Systems

This article deals with options for how to express the luminous flux from outdoor electrical substations of the electric transmission system. Processing of the models of light emissions before and after refurbishment of lighting systems was motivated by setting out rules for the design and erection of refurbished lighting systems in outdoor electrical substations, which are most commonly built in inhabited rural areas with low luminance of the background. The proposed model and calculations are based on requirements of international standards and recommendations for lighting of outdoor workplaces as well as on internal regulations of the ČEPS (Czech Transmission System Operator). These requirements are implemented in real electrical substations and lighting models that are extended by the calculation space of the software goniophotometer. The software goniophotometer was used to evaluate light distribution characteristics of entire electric stations in various situations. This article assesses the impact of different lighting systems installed at electrical substations from the perspective of both direct and total luminous flux directed to the upper hemisphere. It takes into account three outdoor electrical substations (420 kV) of a transmission network and their lighting systems before and after refurbishment. The aim of this article is to determine to what extent the electrical substations contribute to emissions of luminous flux to the upper hemisphere. Results from calculations on models show reduced radiation to the upper hemisphere up to 52.3% after refurbishment of obsolete lighting systems, although total installed flux actually increased due to a change in the ratio of direct and reflected luminous flux after refurbishment of lighting systems.

Development and Validation of a Masking System for Mitigation of Low-Frequency Audible Noise from Electrical Substations

Low-frequency audible noise generated by the magnetostriction effect inherent to the operation of power transformers has become a major drawback, especially in cases where the electrical substation is located in urban areas subject to strict environmental regulations that impose noise limits, differing for day and night periods. Such regulations apply a +5 dB penalty if a tonal component of noise is present, which is clearly the case of magnetostriction noise, typically concentrated at twice the industrial frequency (50 Hz or 60 Hz, depending on the country). The strategy used to eliminate the tonal characteristics, therefore contributing to establish compliance with the applicable regulation and to alleviate the discomfort it causes to the human ear, consisted in superimposing to the substation noise a masking sound synthesized from “sounds of nature” with suitable intensities, to flatten the noise spectrum while enhancing the soundscape. The masking system (heavy-duty speakers powered by a microprocessor platform) was validated at an already judicialized urban scenario. Measurement results confirmed that the masking solution was capable of flattening the tonal frequencies, whose beneficial effect yielded the cancellation of the public civil action filed by the neighbors. The proposed solution is ready to be replicated in other scenarios.

Development and Validation of a Masking System for Mitigation of Low-Frequency Audible Noise from Electrical Substations

Low-frequency audible noise generated by the magnetostriction effect inherent to the operation of power transformers has become a major drawback, especially in cases where the electrical substation is located in urban areas subject to strict environmental regulations that imposes sound pressure limits, differing for day and night periods. Such regulations apply a +5 dB penalty if a tonal component of noise is present, which is clearly the case of magnetostriction noise, typically concentrated at twice the industrial frequency (50 Hz or 60 Hz, depending on the country). The strategy used to eliminate the tonal characteristics, therefore contributing to establish compliance with the applicable regulation and to alleviate the discomfort it causes to the human ear, consisted in superimposing to the substation noise a masking sound synthesized from “sounds of nature” with suitable intensities, to flatten the noise spectrum while enhancing the soundscape. The masking system (heavy-duty speakers powered by a microprocessor platform) was validated at an already judicialized urban scenario. Measurement results confirmed that the masking solution was capable of flattening the tonal frequencies, whose beneficial effect yielded the cancellation of the public civil action filed by the neighbors. The proposed solution is ready to be replicated to other scenarios.

Characterization of nano-additive filled epoxy resin composites (ERC) for high voltage gas insulated switchgear (GIS) applications

Insulation based on epoxy resin (ER) is widely used for high voltage and high fault current rated electrical substation equipment. This paper details the formulation of epoxy based Nano-composites and influence of the Nano filler material on the electrical and thermal properties like breakdown voltage (BDV), relative permittivity, tanδ and thermal conductivity of the epoxy resin composites (ERC). The nano-filler materials such as alumina (Al2O3), silica (SiO2) and titania (TiO2) are considered for the study. Diglycidyl ether of biphenyl-A (DGEBA) type epoxy resin CY5950 and acid anhydride hardener HY5951 are used for development of samples/insulated spacers. Scanning electron microscopy (SEM) images have been established for various ER composites to understand how the dispersion of nano-filler material influences the performance parameters of the samples. In the present study, the sample preparation with metallic inserts has shown additional advantages compared to existing practice of purely insulated samples. Developed samples help to estimate electrical and mechanical properties more accurately. Most appropriate nano filler is identified based on the test results obtained on samples developed in the study. Finally, by using the identified epoxy–filler composite, insulated spacers for 145 kV GIS have been developed and evaluated for electro-mechanical parameters. Necessary dielectric tests have been carried out on developed insulated spacer as per IEC.