Backup power supply of railway transport facilities based on intelligent network technologies
There are objects in the railway transport that are of particular importance for the organization of the transportation process. They are classified as electricity consumers, requiring the implementation of an electricity supply system of increased reliability from three power sources. In modern conditions, the number of these consumers is growing. As a third source, diesel power plants are usually used, the operation of which requires the consumption of expensive energy resources. The article proposes an alternative way of organizing guaranteed power supply of such facilities from a 25 kV contact network using smart grid technologies. The electricity supply system includes the following devices: a phase number converter according to the Steinmetz reversed circuit, which is designed to convert a single-phase voltage into a symmetric three-phase system; active harmonic conditioner, which allows one to reduce the harmonic distortions created by electric locomotives; a controlled source of reactive power with the reactive power control range of -10 ... + 10 Mvar, which maintains the required voltage level at the point of connection of the line supplying the consumer. Computer studies were carried out using the Fazonord software package, designed to simulate the modes of electric power systems and railway power supply systems in phase coordinates. The calculation model is implemented for the electricity supply system of a two-track railway section with six traction substations. The results obtained allowed us to formulate the following conclusions: - reliable and high-quality power supply can be realized only on the basis of the integrated use of active elements, such as a phase number converter, active harmonic conditioner, and reactive power source. In the absence of the reactive power source, significant fluctuations in the voltage at the converter output are observed, as well as a noticeable asymmetry that almost reaches the limit of normal acceptable values. The total voltage harmonic coefficient in the absence of an active filter exceeds 20 %, and the shape of the voltage curve deviates significantly from the sine wave; - in the presence of the whole complex of devices, high quality of electricity is achieved at the consumer substation; - the modeling shows a low sensitivity of the converter circuit under consideration to parameter control errors; - the existing voltage deviations associated with the narrow limits of the reactive power source (-10 ... + 10 Mvar) are of a short-term nature and do not exceed 5 % of the nominal value; - the modeling shows that the transmission of electricity through a single-wire line is possible for a considerable distance, reaching 25 km.