The structure of the park of power transformers with a higher voltage of 6-10 Kv on the example of the electric grid organization of the branch of pjsc «Rosseti center»-«Orelenergo», serving rural electric networks

THE PURPOSE. Evaluation of the power transformer fleet 6-10/0,23-0,4 kV on the example of a branch of PJSC «Rosseti Center»-«Orelenergo».METHODS. In the work, based on the database of the branch of PJSC «Rosseti Center»-«Orelenergo», an analysis was made of the fleet of power transformers with a higher voltage of 6-10 kV in terms of their number, circuits and groups of connection of windings, rated power, terms of service, as well as energy efficiency classes, taking into account the current standards of the technical organization of PJSC «Rosseti».RESULTS. According to the results of the study, it was revealed that among the transformer fleet of the branch of PJSC «Rosseti Center»-«Orelenergo», the number of which is 6026 units, 4528 (73% of the total number) transformers have a circuit and a group of winding connections Y/Y0. The most numerous are transformers with rated capacities of 63 kVA, 100 kVA, 160 kVA, 250 kVA (respectively 853, 1454, 1252, 802 pieces of equipment). It was also revealed that only 268 transformers out of 6206, i.e. 4.3% of the total amount comply with the standard of PJSC «Rosseti» in terms of modern requirements for the level of energy efficiency class.CONCLUSION. A variant of the strategy for replacing power transformers in the branch of PJSC «Rosseti Center»-«Orelenergo» is proposed, within the framework of which trasformers with a given design, circuit and winding connection group, rated capacities and energy efficiency classes are replaced. The implementation of the strategy proposed in the work will make it possible to reduce total electricity losses by 2.3%, as well as increase the share of energy-efficient transformers from 4.3% to 20.4% in the branch of PJSC «Rosseti Center»-«Orelenergo».

Trust Management Issues for Sensors Security and Privacy in the Smart Grid

Currently, smart grids have changed the world, given the great benefits of these critical infrastructures regarding the customers' satisfaction by offering them the electrical energy that they need for their business. Also, the smart grid aims to solve all the problems encountered in the current electrical grid (outage, lack of renewable energy, an excess in the produced power, etc.) by transmitting and sharing the information in real time between the different entities through the installation of the sensors. This chapter therefore presents the architecture of the smart grid by describing its objectives and advantages. In addition, the microgrids are presented as small electric networks. Then, focusing on the security aspects, an analysis of the different attacks and risks faced in the smart grids and more particularly in the microgrids is presented. After, different techniques and suitable security solutions are detailed to protect and secure the various elements of the smart grids and microgrids.

Risk identification in projects of transition to renewable electricity consumption

Due to the increasing electricity consumption in the world, rapid spread of renewable energy sources (RES) and the loss of basic generation capacities the electric networks will become vulnerable. There is stated a threat of periodic blackouts, which will be impossible to control. There has been carried out the study aimed to assess the risks of projects of transition to the consumption of renewable electricity. The general scientific methods of comparative analysis, collection and study of information sources, statistical data analysis and synthesis were used. The brainstorm method was used to identify risks. The relevance and directedness of the modern energy industry development has been proved, taking into account the global environmental trends. A SWOT analysis of the distribution and use of renewable energy was carried out. The damage and probability of the main risks of projects of transition to the consumption of renewable electricity are identified and assessed. There have been proposed the methods of risk management of projects of transition to the consumption of renewable electricity. A complete transition to renewable electricity consumption is found impossible for Russia due to high natural, technological, investment, legal and business risks. There is expected a high probability of technological risks affecting the construction of renewable energy generating structures and their connection to the energy system. It has been inferred that for the country’s energy system, its high level of reliability and the ability to switch to backup power sources at any time are important

Estimation of the potential of energy efficiency increase in SMARTGRID systems with prosum-ers based on electric vehicles

The modes of operation of power transformer substations 6 (20)/0.4 kV are analyzed. Scientific and technical solutions for the use of electric vehicles as prosumers of electric energy are substantiated. The potential influence of electric cars on electricity losses in "smart" electric networks is determined. Feasibility study of expediency of using electric mobiles as prosumers from the standpoint of loss reduction and efficiency of network equipment use is given. Quantitative indicators of the potential of equalization of the daily schedule of electric loads of the typical area of consumers of city electric networks are determined. The main indicator is the reduction of electricity losses in transformers by 7-10% compared with the existing ones when regulating the mode from the side of 0.4 kV with help of electric vehicles. Additionally, the possibility of increasing the capacity of electrical networks up to 45% identified.

Reducing the cost of electricity transmission services of industrial enterprises connected to the electric networks of electric power producers

Reducing the cost of electricity consumption by industrial enterprises is the most important area of increasing the operational efficiency of their activities. The article is devoted to the issue of reducing the cost of paying for the service component of the transport component of purchased electrical energy from industrial enterprises that have technological connection to the electrical networks of electricity producers. The article makes an empirical study of the features of the pricing of payment for the services of the transport component of purchased electrical energy for industrial enterprises connected to the electric grids of electricity producers with the identification of factors influencing the overestimation of the cost of paid electricity, and calculating such overestimations using the example of a typical schedule of electricity consumption of a machinebuilding enterprise for various regions Russia. On the basis of the developed author's indicators (tariff coefficient for electricity transportation by the level of GNP, index of tariff coefficient for electricity transportation, weighted average price for electricity transportation, index of weighted average price for electricity transportation, integral index of efficiency of GNP tariffs) study of the effectiveness of the application of tariffs for the transport of electricity for industrial enterprises connected to the electric networks of electricity producers. Based on the calculated indicators, the article groups the regions into three main groups, with the development of recommendations for managing the cost of purchasing electricity by the component of the cost of the transport component of purchased electricity in each group. As the most optimal option for reducing the cost of electricity transportation, the author proposes the introduction of demand management for electricity consumption, which will reduce the costs of industrial enterprises that pay for the transport component of purchased electricity at unfavorable tariff configurations.

Influence of Harmonics on the Working Efficiency of a 6/1.2 kV Transformer in a Pit Mine

Explosion-proof transformers 6/1.2 kV is important electrical equipment responsible forsupplying electricity in underground mine electrical networks. A failure of this transformer will cause aninterruption in the power supply and loss of safety in underground mining. Usually, explosion-prooftransformers in underground mine electrical networks are designed and manufactured to work with idealparameters such as sinusoidal currents, and the network structure is symmetrical. However, today inunderground mine electric networks, many power electronics are connected to the network, such asinverters and soft starters. As a result, a current flowing through the transformer is non-sinusoidal,overloading the transformer even by working with the design specifications. This paper studies theinfluence of harmonics on the working efficiency of a 6/1.2 kV transformer in a pit mine. Research resultssuggest reasonable solutions for transformer operation to ensure longevity and not cause damage to thetransformer.

Two-Stage Robust and Economic Scheduling for Electricity-Heat Integrated Energy System under Wind Power Uncertainty

As renewable energy increasingly penetrates into electricity-heat integrated energy system (IES), the severe challenges arise for system reliability under uncertain generations. A two-stage approach consisting of pre-scheduling and re-dispatching coordination is introduced for IES under wind power uncertainty. In pre-scheduling coordination framework, with the forecasted wind power, the robust and economic generations and reserves are optimized. In re-dispatching, the coordination of electric generators and combined heat and power (CHP) unit, constrained by the pre-scheduled results, are implemented to absorb the uncertain wind power prediction error. The dynamics of building and heat network is modeled to characterize their inherent thermal storage capability, being utilized in enhancing the flexibility and improving the economics of IES operation; accordingly, the multi-timescale of heating and electric networks is considered in pre-scheduling and re-dispatching coordination. In simulations, it is shown that the approach could improve the economics and robustness of IES under wind power uncertainty by taking advantage of thermal storage properties of building and heat network, and the reserves of electricity and heat are discussed when generators have different inertia constants and ramping rates.

Nonlinear load influence on single-phase fault current in shipboard electric networks

Описаны результаты исследований влияния показателей качества электроэнергии на токи однофазных замыканий в судовых электроустановках. Выявлены основные элементы бортовых электроустановок, влияющие на качество электроэнергии. Проанализировано формирование высших гармоник в токе однофазного замыкания. На физической модели электроустановки проведены исследования влияния нелинейной нагрузки на ток однофазного замыкания. Результаты экспериментов подтвердили установленные закономерности. Выявлено, что в установившемся режиме ток однофазного замыкания определяется не только величиной фазной емкости и напряжением сети, но и несинусоидальностью тока нагрузки. Экспериментально показано, что высшие гармоники, присутствующие в токе нагрузки, усиливаются в токе однофазного замыкания. При этом увеличение их амплитуд пропорционально номеру гармоники и ее амплитуде в токе нагрузки. Экспериментально установлено, что формирование высших гармоник в токе однофазного замыкания в результате эмиссии нелинейной нагрузкой приводит к увеличению его действующего значения. The paper represents the research results of the power quality indicators influence on the currents of single-phase ground faults in ship electrical installations. The main elements of on-board electrical installations that affect the quality of electricity are identified. The process of higher harmonics formation in the single-phase ground fault current is analyzed. Studies of the nonlinear load influence on the single-phase fault current are carried out on the physical model of the electrical installation. The experimental results confirmed the established patterns. For the steady-state mode it was discovered that the single-phase ground fault current is determined not only by the phase capacitance value and the mains voltage, but also by the non-sinusoidality of the load current. It has been shown experimentally that the higher harmonics of the load current are amplified in the single-phase ground fault current. In this case, the increase at their amplitudes is proportional to the harmonic number and its amplitude in the load current. It has been experimentally established that the formation of higher harmonics at a single-phase ground fault current as a result of emission by a nonlinear load leads to an increase in its effective value.

Development of a Spatiotemporal Database for Evolution Analysis of the Moscow Backbone Power Grid

Currently in the field of transport geography, the spatial evolution of electrical networks remain globally understudied. Publicly available data sources, including remote sensing data, have made it possible to collect spatial data on electrical networks, but at the same time a suitable data structure for storing them has not been defined. The main purpose of this study was the collection and structuring of spatiotemporal data on electric networks with the possibility of their further processing and analysis. To collect data, we used publicly available remote sensing and geoinformation systems, archival schemes and maps, as well as other documents related to the Moscow power grid. Additionally, we developed a web service for data publication and visualization. We conducted a small morphological analysis of the evolution of the network to show the possibilities of working with the database using a Python script. For example, we found that the portion of new lines has been declining since 1950s and in the 2010s the portion of partial reconstruction reached its maximum. Thus, the developed data structure and the database itself provide ample opportunities for the analysis and interpretation of the spatiotemporal development of electric networks. This can be used as a basis to study other territories. The main results of the study are published on the web service where the user can interactively choose a year and two forms of power lines representation to visualize on a map.