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The islanded mode of operation of an electric power system (EPS) that has generation capabilities provided by conventional thermal power plants, by a pumped-storage power station, or from an interlink with a neighboring electric power system through an HVDC BtB converter is addressed in this paper. The risk for electrical power systems to fall into an islanded mode has recently grown, as it is caused not just by technical reasons but by a geopolitical situation as well. The current strains demand the close consideration of problems related to EPS operation in an islanded mode. This paper considers several. The research covers the following issues. The response of the islanded system to a sudden and spasmodic load change is analyzed in cases when the system deals with the disturbance with internal resources alone and with the help of an HVDC BtB converter’s frequency control functionality. Analysis of the impact of the settings of the HVDC BtB converter on the system’s response to disturbances is presented and the optimal set of parameters found. The impact of the system’s extended inertia on the system’s response is evaluated by using an additional unit of the pumped-storage power station in synchronous condenser mode. Transients in the system when switching a unit operating in synchronous condenser mode on and off are analyzed. The capability of the system to withstand major disturbances, such as disconnection of the pumped-storage power station’s unit operating in a pump mode and disconnection of the HVDC BtB converter in emergency modes, if a situation demands, is researched. The research is carried out by numerical simulations using PSS Sincal Electricity Basic software. Updated operating parameters of the isolated power system and the LCC HVDC BtB converter, as well as frequency control automation provided by ABB, were used in the simulations.

Purpose of this paper is to evaluate the current street lighting condition and energy saving possibilities using new light emitting diode (LED) technologies in the main cities of Lithuania. The power consumption evaluation model has been used for comparison of current high-pressure sodium (HPS) lamp technology and available LED technologies. The model enables to evaluate luminous flux losses as well as electric power losses. The calculations have been carried out for the largest Lithuanian cities and the following conclusions have been made. The current HPS technology was implemented in towns about 10-15 years ago. Now the life time of those luminaries is being expired. So the renovation of street lighting systems would be necessary in the nearest future. It was determined that the implementation of LED technologies (due to higher efficiency of LEDs, smaller energy losses in luminaire optics, more effective distribution of luminous flux and other advantages) enables to achieve electric power reduction by 20-60%. This mostly depends on power of the HPS lamp to be replaced and the quality of LED luminaires. The expedience of the current luminaire replacement by LED luminaire depends on the street lighting condition characteristics such as type and power of luminaire, maintenance duration and others. Most energy efficient replacement by LED luminaires should be carried out in the narrow residential streets where luminance levels exceed the requirements of standards now.

Purpose -The purpose of this paper is to determine conformity of geometrical parameters between the elements embroidered with photoluminescent threads and their digital images as well as to explore the change in photoluminescent radiation. Design/methodology/approach -Using some different methodologies and apparatus, analysis shape of embroidered elements conformity and photoluminescent luminance attenuation are analysed. Findings -The provided methodologies allow assessing the quality of embroidered elements area and photoluminescent properties. Originality/value -The proposed approach can be adjusted to investigate photoluminescent properties of embroidered elements of different filling types.

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