Energy efficiency and energy saving at all times and especially at the present stage of development of industry and economy have played an extremely important role. Regardless of which countries and according to what criteria they build energy development plans, energy efficiency and energy saving are always a priority. This fully applies to the mineral resources complex, in which energy consumption as a whole makes up a large share of total consumption. The resources mined in the mineral resources complex are themselves a source of energy. The energy sector is evolving in many ways. Many scientific works, the results of which are reflected in publications, confirm the relevance of research in the energy efficiency field. But the approach to individual decisions in the mineral resource industry is specific and it is worth of separate consideration. Recently, much attention has been paid to “green energy” and renewable energy sources. However, energy efficiency in the field of traditional generation and consumption remains an urgent problem and its solution is in constant development. One of the main directions for improving energy efficiency is the development of autonomous systems for the electrical and thermal power engineering. All these problems are reflected in a special volume of the Journal of the Mining Institute, the articles are divided into four sections: energy efficiency of the electric drive in the mineral resources complex (MRC); energy efficiency of industrial plants and enterprises in MRC; power quality and renewable sources in MRC; autonomous power supply systems in MRC. The presented articles contain valuable material from the scientific and practical points of view and can form the basis for further research in the energy efficiency field.
The power supply system is affected by external disturbances, so it should be stable and operate normally in compliance with power quality standards. The power supply system goes into abnormal modes operation when, after a short-term failure or disturbance, it does not restore normal mode. The electrical complex, which includes a wind power plant, as well as a battery and a diesel generator connected in parallel, is able to provide reliable power supply to consumers which meets the power quality indicators. The article develops an algorithm that is implemented by an automatic control system to select the operating mode depending on climatic factors (wind) and the forecast of energy consumption for the day ahead. Forecast data is selected based on the choice of the methods, which will have the smallest forecast error. It is concluded that if the energy consumption forecast data is added to the automatic control system, then it will be possible to increase the efficiency of the power supply complex. In the developed algorithm the verification of normal and abnormal modes of operation is considered based on the stability theory. The criteria for assessing the normal mode of operation are identified, as well as the indicators of the object’s load schedules for assessing the load of power supply sources and the quality standards for power supply to consumers for ranking the load by priority under critical operating conditions and restoring normal operation are considered.
Cuba is traditionally considered a country with an underdeveloped industry. The share of the mining and metallurgical industries in the gross industrial production of the republic is small – about 3 % of GDP. The development of deposits and the extraction of nickel ores is an important sector of the economy of the Republic of Cuba, since the largest reserves of nickel and cobalt on the North American continent are located on the territory of the country. The development of the country energy system can serve as a growth factor in this sector of the economy. Due to climatic features and impossibility of integrating new capacities into the energy system through the construction of hydroelectric power plants, solar energy is a promising direction. Determining the feasibility of using solar tracking systems to increase the generation of electricity from solar power plants is one of the main challenges faced by engineers and renewable energy specialists. Currently, there are no solar tracking systems in Cuba that can provide information to assess the effectiveness of this technology in the country. The lack of the necessary technologies, as well as the high cost of developing solar power plants with tracking systems, limit the widespread introduction of such complexes. Hence follows the task of creating an inexpensive experimental model that allows assessing the effectiveness of tracking systems in specific weather conditions of the Republic of Cuba. This model will allow in future to increase the efficiency of electrical complexes with solar power plants, which provide power supply to the objects of the mineral resource complex and other regions.
This paper presents a control philosophy for multiterminal DC grids, which are embedded in the main AC grid. DC transmission lines maintain higher power flow at longer distances compared with AC lines. The voltage losses are also much lower. DC power transmission is good option for Russian north. Arctic seashore regions of Russia don't have well developed electrical infrastructure therefore power line lengths are significant there. Considering above it is possible to use DC grids for supply mining enterprises in Arctic regions (offshore drilling platforms for example). Three different control layers are presented in an hierarchical way: local, primary and secondary. This whole control strategy is verified in a scaled three-nodes DC grid. In one of these nodes, a modular multilevel converter (MMC) is implemented (five sub-modules per arm). A novel model-based optimization method to control AC and circulating currents is discussed. In the remaining nodes, three-level voltage source converters (VSC) are installed. For their local controllers, a new variant for classical PI controllers are used, which allow to adapt the values of the PI parameters with respect to the measured variables. Concerning the primary control, droop control technique has been chosen. Regarding secondary level, a new power flow technique is suggested. Unbalance conditions are also verified in order to show the robustness of the whole control strategy.
The article discusses the issues of identifying the location of non-linear loads in electrical networks which makes the main contribution to the distortion of the non-sinusoidal voltage and current in the distribution network of an industrial enterprise, including mining enterprises. The existing methods for determining the location of the source of higher harmonic components in voltage and current are considered, their advantages and disadvantages are revealed. The main disadvantages of the methods used include the low accuracy and incorrectness of their use in existing enterprises. When developing a new method, the authors were faced with the task of simplicity of its use in the conditions of industrial operation of electrical equipment and the absolute correctness of the results obtained. The proposed method of identifying the source of higher harmonics is based on the variation of the parameters of the power system, in particular, the change in resistance of power transformers taking into account their transformation ratio. It is shown that by varying the transformation ratio during regulation under load, the total coefficient of the harmonic components of the voltage changes. Based on the constructed dependencies, the variation of the derivative of this function with different variations of the parameters of sources of higher harmonics is analyzed and a method is developed that allows determining the share contribution of consumers to the total harmonic component of the voltage.
In the recent years, the researchers and experts in the field of energetics often mention in their publications a need to reduce power transmission losses. Among different ways to accomplish this goal the method of the company load leveling stands out due to its simplicity, accessibility and efficiency. The paper proposes a new assessment factor for additional power losses in distribution network. It is known that dispersion of the load curve correlates with the amount of power losses, which is why the proposed factor is put in a position of dependency on the shape of the load curve of the company. It is demonstrated that the proposed factor can help to identify without any strain a need in technical measures for levelling the load curve of the company and to assess efficiency thereof.
The article deals with equivalenting of complex electrical networks of industrial enterprises. In the article the different methods of averaging equivalenting elements in power systems are compared, specifically, the method of moments, the equivalent section method, and the average value method. The current value of the capacitor bank as part of the electrotechnical complex of the enterprise is the main criterion for determining the equivalenting error of the electric network. The equivalenting in the presence of high harmonics in electrical networks of the enterprise is considered by applying the methods under discussion. Comparison of these equivalenting methods in the presence of high harmonics shows that the error in the calculation of capacitor bank current ranges from 3,8 to 14,7 %. In addition, the most accurate method for determining the capacitor bank overload is the method of moments.
In this article considered the rational formation of the complex electrical load schedule. Application of this method allows to achieve savings in the payment of electricity and increase the possibility of energy transfer. The effect is achieved by uniform distribution of energy consumption during the day.
In article the new approach to modelling of processes arising in the presence of the frequency electric drives is offered, offering to consider corners of shift of phases on various harmonics. Research of power characteristics of a frequency drive was spent on the basis of the spent experiment.
The optimization of reactive power compensation in the presence of harmonics in the electrical network complex is a complicated computational problem. The authors propose a calculation method that significantly reduce the computation procedure and still get the desired result as the choice of device parameters for reactive power compensation and harmonics filters.
This work contains brief analysis of high harmonics reduction methods. It is offered to make a choice between reduction methods of high harmonics influence on condenser batteries depending on factors of harmonics occurrence. Definition algorithm for the most effective method of high harmonics reduction on condenser batteries operation is created.
This work contains one of methods reduction high harmonics in electric networks of the industrial enterprises. Considering the maintenance of inductive and capasitor elements in a network the offered way is based on changing peak-frequency characteristic of network unit. Such changing is possible connecting additional reactors which parameters are defined by deciding various problems. The offered way is more economic in comparison with filter-compensating devices.
Повышение эффективности работы калийных рудников связано с совершенствованием всех звеньев технологического процесса по добыче калийной руды и, в первую очередь, с обеспечением бесперебойной и надежной работой добычных и транспортных машин, устойчивая и высокопроизводительная работа которых зависит от качества электрической энергии в подъемной распределительной сети ...
Распределительные сети калийных рудников отличаются большой протяженностью отходящих кабельных линий б кВ и большой мощностью потребителей, что вызывает отклонения напряжения на зажимах электроприемников свыше 10% ...
Имея в виду целесообразность применения продольно-поперечной компенсации в подземных сетях калийных рудников, произведем анализ режимов работы рудничной распределительной сети, характерный для производственного объединения «Белорускалий» ...
