No abstract

No abstract

No abstract

No abstract

No abstract

Decentralization of electricity generation based on distributed generation plants is an important segment of the new technology platform for the power industry. On the basis of this approach, significant positive effects can be obtained, which consist in reducing financial costs of energy supply, increasing the uninterrupted power supply, improving the quality of electricity and stimulating the use of renewable energy sources. Effective use of distributed generation in electric power systems requires the development of methods and tools that provide coordinated management of normal, emergency and post-emergency modes. Of particular relevance is the problem of determining the limit operating modes of networks, at the nodal points of which relatively low power generators are connected. In some situations, for example, when using small hydraulic stations, groups of such generators can be located at significant distances for 6-10-20 kV distribution networks from consumption centers. In this case there will be a noticeable limitation of the regions of static aperiodic stability. The article presents the results of developments aimed at implementing methods for determining the limit operating modes by static aperiodic stability in networks with distributed generation plants. The proposed approach is based on the limit modes equations which provide the formation of effective algorithms for the operational finding of points belonging to the boundaries of stability regions. The results of the construction of the indicated areas for a 6 kV electric network with distributed generation plants based on low-power hydraulic stations are presented. Additionally, the transient processes in the studied electric power system were simulated in the Matlab system for various space points of the controlled mode parameters.

Rectifier locomotives have non-linear current-voltage characteristics and generate higher harmonics (HH) in the power supply networks, which is accompanied by the following negative effects: reduced equipment service life, distortion of electricity metering, occurrence of resonant processes, etc. Therefore, the problem of reducing the levels of harmonic distortion in the networks adjacent to the traction substations of the AC railways is of increased relevance. The level of HH generation depends on the design features of electric locomotives. Electric stock with zone-and-phase regulation creates high harmonic distortions, which results in increased losses, increased electromagnetic effects on adjacent power and telecommunication lines and reduced reliability of power supply. Electric locomotives with asynchronous traction motors (ATM) connected via 4q – S converters virtually do not distort the sinusoidality of the current curve. To measure the degree of reduction of harmonic distortion during the movement of locomotives with ATM, simulation modeling of non-sinusoidal modes of a typical 25 kV traction power supply system was carried out for two variants of the locomotives used: 1) VL-80R with DC motors; 2) UTY –1 with asynchronous traction motors. The methodology for determining non-sinusoidal modes is based on the technology of modeling electric power systems (EPS) in phase coordinates; at the same time, the models of EPS elements were formed as lattice schemes characterized by a fully connected topology. The parameters of these circuits can be recalculated to the frequencies of HH. The proposed approach is universal and can be used to study non-sinusoidal modes in existing and future traction power supply systems. The simulation results showed that the problem of increased harmonic distortion in the networks feeding the traction substations can be completely solved by replacing the acting locomotives with new-generation electric locomotives with asynchronous electric drives and four-quadrant converters.

The goal is to develop a methodology for modeling electric power supply systems for railways equipped with a complex of devices implemented using smart grid technologies. The results obtained showed that a reliable and high-quality electric power supply for traction of trains and non-traction consumers could be implemented on the basis of the integrated use of Smart Grid active elements, such as a phase converter, an active harmonic conditioner, a controlled reactive power source and a distributed generation plant. On the basis of computer simulation, it has been established that in the absence of reactive power sources, noticeable voltage fluctuations are observed on the 10 kV buses of a non-traction consumer. The asymmetry approaches the limit of normally permissible values; turning off the active filter leads to an increase in the total voltage harmonic distortion up to 16%; in the presence of the whole complex of active devices, high quality of electricity is achieved. The phase number converter is robust and has low sensitivity to parameter setting errors; voltage deviations caused by a limited range of changes in reactive power in its source are short-term and do not exceed values acceptable for practice. Thus, on the basis of Smart Grid technologies, it is possible to implement the connection of distributed generation plants directly to the traction network using a device for transducing the number of phases, formed according to the inverted Steinmetz’s circuit. Elimination of harmonic distortions created by rectifier electric locomotives is carried out by means of an active conditioner of higher harmonics. A controlled reactive power source can be used to maintain voltage levels.