Identification of the flicker source in the power supply systems

THE PURPOSE. To consider issues related to the study of methods for determining the sources of violations of the quality of electrical energy in power supply systems, in particular consumers which create rapid voltage changes or voltage fluctuations that create rapid changes in the luminous flux in electric lighting installations. Show that electrical receivers with a sharply variable operating mode are sources of fluctuations in the consumed current and voltage in the electrical network of power supply systems, which in turn manifests itself in the form of unacceptable values of one of the indicators of the quality of electricity - flicker, defined as the subjective perception of fluctuations in the luminous flux of lighting devices. To study the possibilities of determining the places of occurrence of significant voltage fluctuations without the use of expensive and complex instruments for measuring flicker values in the electrical network. To develop a simplified method for determining the locations of electricity consumers that negatively affect the operation of electric lighting systems and, ultimately, the vision of personnel. Conduct a check on a computer model of a simplified method for determining the places of occurrence of voltage fluctuations that are inadmissible in their magnitude, which are expressed in the appearance of significant doses of flicker that exceed the standard values.METHODS. Solving the problem, a computer model was used, created in the Simulink extension package of the Matlab scientific and technical calculation system.RESULTS. The article describes the relevance of the problem, discusses the quality of electricity in power supply systems. It has been shown using experimental data that in electrical networks there is an excess of the standard values of flicker doses. The possibility of using interharmonic components of the mains voltage to determine the sources of unacceptable doses of flicker is considered. A simplified method for finding flicker sources based on obtaining the values of the derivatives of currents at various points of the electrical network is presented. Computer simulation of an electrical network diagram with electrical receivers, which have both calm and sharply variable nature of work, has been performed. It is shown that the use of the values of the derivatives of the current at various points of the electrical network makes it possible to identify the sources of the occurrence of unacceptable doses of flicker.CONCLUSION. The occurrence of significant rapid voltage changes in the electrical network negatively affects vision, which is inevitably accompanied by increased personnel fatigue and can lead to industrial injuries. The results obtained by the authors of the article show that it is possible to use it to determine the places of occurrence of large voltage fluctuations, which are manifested in unacceptable doses of flicker of the derivatives of currents. It should be taken into account when conducting surveys of power supply systems in order to use fairly simple hardware to identify sources of disturbance in the quality of electrical energy.

PRODUCTIVITY AND QUALITY EVALUATION OF TARRAGON AND THYME GROWN UNDER ARTIFICIAL LIGHT

The research aimed at evaluation of productivity and quality of tarragon and thyme medicinal material was carried out on hydroponic installations during 2019-2020. The objects under study were Monarkh and Gudvin tarragon varieties as well as Medok and Zmeyka thyme varieties. The plants were grown in mineral cotton substratum. Fertikea Hydro complex fertiliser with microelements and calcium nitrate were used. The growing conditions: ambient temperature +22…+25℃, solution temperature +20℃, ambient humidity 55…65%. Experiment regimens: growing under white LEDs (luminous flux 8000 lm, color temperature 4000 K, PPF 165 mkmol/s/m2) and color LEDs (combination of red, blue and white LEDs (32:16:32), luminous flux 6573 lm, PPF 143 mkmol/s/m2), for 16-hour light regimen. We found that thyme grown on a vertical hydroponic system increase its biomass 2.0…3.5 times compared to the conventional growing. The highest productivity of Zmeyka thyme variety is reached under white light, while for both the tarragon varieties and Medok thyme variety it is reached under coloured LEDs. Chlorophyll-a content in green biomass is a little higher under coloured LEDs for Zmeyka thyme variety and Gudvin tarragon variety, while the reverse trend is observed for Monarkh tarragon variety. All the varieties show higher chlorophyll-b content under coloured LEDs. Combined chlorophyll-a and chlorophyll-b content increases under coloured LEDs for the thyme varieties and Gudvin tarragon variety. Monarkh tarragon variety shows the highest combined chlorophyll content under white LEDs. Carotenoid concentration in Medok thyme variety and Monarkh tarragon variety is higher under white LEDs and it is higher under color LEDs for the rest of the varieties. Flavonoids in the studied varieties accumulate statistically better (1.5…3.0 times) under white LEDs

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.

Explanations of some technical requirements for fire lanterns

В статье отражены результаты обсуждения наиболее актуальных вопросов, возникших при формировании технических требований к фонарям пожарным при разработке межгосударственного стандарта «Техника пожарная. Фонари пожарные. Общие технические требования. Методы испытаний». Предложения, требующие подробных разъяснений, касаются количества циклов применения фонаря, обоснования принятого уровня освещенности и разработки требований к нормированию светового потока источника света фонаря. На основании качественных испытаний четырех наиболее распространенных моделей групповых фонарей в подразделениях противопожарной службы Российской Федерации, проведенных испытательной лабораторией института в период с 2010 по 2018 год, сформулированы основные их эксплуатационные показатели. This article contains some comments and suggestions that caused a discussion during the consideration of the draft of the interstate standard provisions “Fire fighting equipment. Fire lanterns. General technical requirements. Test methods”. The proposals that require detailed explanations include issues related to the cycle life of lamp, the justification of the accepted level of illumination and the development of requirements for the normalization of the luminous flux of the lamp light source. As a reference point for determining the cycle life of the flashlight there was selected the battery. Based on the standard indicators of the resource of different types batteries the value of cycle life of the flashlight is equal to 400. On the base of the qualitative tests on the four most common models of group lamps in the divisions of the fire service of the Russian Federation, conducted by the testing laboratory of the Institute for the period from 2010 to 2018, the main operational indicators are formulated as the following: “The time of continuous illumination of the lamp under normal conditions according to GOST 15150, excluding the time of triggering the warning alarm (FPG), should be at least 5 hours; the illumination of the working surface with the lamp must be at least 1500 lux during the entire glow time”. The introduction of requirements for the normalization of the luminous flux of the light source of the lamp is not provided.

ACCURATE MEASUREMENT OF ULTRAVIOLET LIGHT-EMITTING DIODES

We have developed a new calibration capability for 200 nm to 400 nm ultraviolet light-emitting diodes (UV LEDs) using a Type D gonio-spectroradiometer. The recently-introduced mean differential continuous pulse (M-DCP) method is used to overcome the measurement difficulty associated with the initial forward voltage, VF, anomaly of a UV LED, which makes it impossible to use VF to infer junction temperature, TJ, during pulsed operation. The new measurement facility was validated indirectly by comparing the measured total luminous flux of a white LED with that measured using the NIST’s 2.5 m absolute integrating sphere. The expanded calibration uncertainty for the total radiant flux is approximately 2 % to 3 % (k = 2) depending the wavelength of the UV LED.

IEA 4E SSL ANNEX INTERLABORATORY COMPARISON OF GONIOPHOTOMETERS MEASURING SOLID STATE LIGHTING PRODUCTS – RESULTS

The global interlaboratory comparison (IC 2017) on measurements of solid-state lighting (SSL) products with goniophotometers was conducted under the International Energy Agency 4E Solid State Lighting Annex with 36 participating laboratories from 19 countries with a total of 42 goniophotometric instruments including mirror-type, near-field type and source-rotating type goniophotometers. A narrow-beam LED lamp and three different types of LED luminaires, including a street lighting luminaire, were used as comparison artefacts for measurements of 16 different quantities. These included electrical, photometric, and colorimetric quantities, and goniophotometric quantities such as centre beam intensity, beam angle, partial flux (15° cone angle), and angular colour uniformity. CIE S 025 was used as the test method. The results demonstrated overall good agreement on luminous flux and colour quantities, however, larger variations and various problems were identified in goniophotometric quantity results. Near-field type and source-rotating type goniophotometers showed equivalent accuracies overall to those of far-field mirror type goniophotometers.

COMPARISON OF LUMINOUS FLUX MAINTENANCE METHODS, CONTINOUS VS. ON/OFF CYCLES

This paper will present preliminary results from a research project comparing two methods for estimating the lifetime of LED products, LM-84 (6000 h test) and the new EU endurance test (3600h test) including on/off cycling, that will be required by EU from 2021. Beside the luminous flux development for the sources tested, their colorimetric results will also be examined as a function of time. Preliminary results for two series of LED products will be presented. For one series, the 3600h test have been completed, for the remaining series only results from the 6000h test is available. Results of the luminous flux and colour maintenance will be presented. Initial examinations shows good agreement between the two tests methods for the first series of LED products measured.

MODELLING OF VERTICAL SURFACES RADIATION IN CONNECTION WITH THE EVALUATION OF THE OBTRUSIVE LIGHT

The issue of the luminous flux radiation to the upper hemisphere is very broad and complex. The paper deals with the modelling of the vertical surface radiators. It presents an approach to unify the behaviour of these types of light sources. These will be understood as cosine radiators. If this cosine distribution curve is taken into account, then only the luminance and the light-active surface can be known to supplement the information about the radiation of such the light source. The luminance and radiated surface can be obtained relatively easily from real field measurements. The article presents the implementation of this data into lighting calculations and the creation of the distribution curves which are necessary for the radiation calculations of these surfaces. It also analyses the influence of the luminance and active areas on the radiated luminous flux and assign these values to the real radiators.

Eco-friendly sun lamp for railway facilities

The paper considers the possibility of using a pulsed discharge in cesium as an environmentally friendly high quality light source for lighting industrial premises of railway transport facilities. The use of cesium filling of standard sapphire burners of high-pressure sodium lamps and a pulsed mode of electric power supply of the discharge to create a light source has been substantiated. A mathematical model of a high-pressure pulsed discharge in cesium is formulated on the basis of the radiative gas dynamics equations. The discharge was simulated and it was shown that it is possible to create a plasma with a temperature 4000 -7000 K and a pressure of 0.5 - 1.5 at m with the power supplied to the discharge ∼ 100 W/cm in the steady-state combustion mode. The dependence of the discharge lighting characteristics on the amplitude of the current pulses and the amount of cesium in the gas discharge tube is analyzed. It is shown that in a wide range of currents and plasma densities, the color rendering index of the discharge radiation Ra> 95 with luminous efficacy ηV ∼ 70lm/W and more. The average luminous flux emitted per unit length of the discharge column is ∼ 104 lm/cm. The color temperature of the discharge radiation can vary over a wide range of values Tc∼ 3000÷4500 K. It is shown that the color coordinates Xc,Yc of discharge radiation are close to the values Xc,Yc of a blackbody. The use of such a source in conditions of a short daylight hours will make it possible to create practically solar illumination of large production areas.

Using CaCO3-doped package to improve correlated color temperature uniformity of white light-emitting diodes

<span>The white light-emitting diode (WLED) has been the most advance lighting method currently, however, the fabrication process of this configuration still has drawbacks which negatively affect its color quality. This research was conducted to provide a method for WLED’s lighting output enhancement. Since CaCO₃ particles are excellent for thermal stability enhancement, especially when being combined with an adhesive substance, we decided to integrate CO₃ particles into resin matrix such as melamine formaldehyde (MF) and investigate their influences on the optical properties, including color uniformity and lumen output, of the WLED. The results showed that CaCO3 and MF resin are beneficial to the light scattering efficiency, which results in higher luminous flux and chromatic quality for WLED packages. In addition to that, the appropriate amounts of MF resin and CaCO₃ for reaching the best lumen efficiency and color quality are figured out at 1% and 10%, respectively. Moreover, another advantage of using MF resin and CaCO₃ for fabricating WLEDs is cost effectiveness. Hence, it has turned out that CaCO₃ and MF resins can be potential materials for next high-quality WLED generations.</span>