Electrodynamics of Reactive Power in the Space of Inter-Substation Zones of AC Electrified Railway Line

Abstract

In railway traction, the definition of “electromagnetic field” is functionally connected to the concept of the reactive power consumed by the electric rolling stock, and characterized by the running and standing electromagnetic waves in the space of the inter-substation zones from the site of the AC traction system. Such a definition is established and theoretically justified by the theory of electromagnetic fields. This article uses the methodology of this theory, in particular, a method for power balance estimation in electromagnetic fields based on Maxwell’s equations, as well as methods for the analysis of running and standing electromagnetic waves based on the theory of reflection, propagation and transmission of plane harmonic waves. The research considers the regularities of standing electromagnetic waves in the space of inter-substation zones of electric traction systems, which occur due to the incomplete reflection of incident waves from the contact wire and metal parts of the roof surface and the frontal part of the body of the electric rolling stock. The flow of electricity to the roof surface and the frontal part of the body of an electric locomotive is considered. The possibility of using existing methods to reduce wave reflections and thereby to effectively compensate for reactive power in the space of inter-substation zones is discussed.

Electrodynamics of Power Losses in the Devices of Inter-Substation Zones of AC Electric Traction Systems

“…In this regard, the authors of this article propose a new so-called "field" approach to assess power losses in electric traction systems; that is, an approach based on the theory of the electromagnetic field, according to which the transmission of electricity by quantity and direction is characterised by the Poynting vector → S [9,10]: Works [18,19] have significant theoretical and practical investigations dedicated to waves propagation in the overhead wires and accurate calculations of magnetic field intensity in general applications. At the same time, a significant number of publications, for example [20][21][22][23][24][25][26][27], present the results of determining, by calculation or experiment, the strengths of electric → E or magnetic → H fields at various points in the spaces of electric traction systems.…”

“…At the same time, electromagnetic waves propagating in the airspace of the inter-substation zone meet catenary wires, electric rolling stock, carriages, and rails on their way. They are partially reflected from the surfaces of these structures [9,10], and partly they penetrate and dissipate in them in the form of heat losses, the determination of which is the primary purpose of this article.…”

“…In our opinion, this is due to the fact that traditional methods for analysis and reduction in energy losses in electric traction networks are based on the "circuit" approach, that is, on the theory and electrical appliances of electrical circuits, which follows from the analysis of publications [1][2][3][4][5][6][7][8]. This article continues and expands on the researches outlined in [9,10]. Let us summarise them shortly.…”

“…The approach is based on the fundamental law of electromagnetic energy propagation, i.e., on the fact that energy is distributed not by wires but by dielectrics (in particular, by the air) and is transmitted not by current but by electromagnetic waves. It was shown that the electricity required to move trains and trams, propagating through the airspace of the inter-substation zone, enters the electric rolling stock through the roof and bottom of its body, i.e., the electromagnetic energy enters the inside of the electric locomotive through the roof porcelain insulator and through the air holes in the bottom of the locomotive body [9,10]. Based on the "field" approach of electromagnetic energy propagation from the traction substation to the electric rolling stock described in [9], the next research published in [10] showed that the reactive power consumed by the electric rolling stock is characterised by the standing waves formed in the airspace of the inter-substation zone by the superimposition of the waves falling on the elements of electric traction (contact wire, rails, locomotive and car bodies), and the waves reflected from the surfaces of these elements and devices.…”

“…It was shown that the electricity required to move trains and trams, propagating through the airspace of the inter-substation zone, enters the electric rolling stock through the roof and bottom of its body, i.e., the electromagnetic energy enters the inside of the electric locomotive through the roof porcelain insulator and through the air holes in the bottom of the locomotive body [9,10]. Based on the "field" approach of electromagnetic energy propagation from the traction substation to the electric rolling stock described in [9], the next research published in [10] showed that the reactive power consumed by the electric rolling stock is characterised by the standing waves formed in the airspace of the inter-substation zone by the superimposition of the waves falling on the elements of electric traction (contact wire, rails, locomotive and car bodies), and the waves reflected from the surfaces of these elements and devices. The authors proposed two ways to reduce the reactive power which arises as a result of the formation of standing waves-either by the "suppression" (damping) of the already formed standing waves or by preventing the formation of reflected waves by the application of special thin film coatings (single or multi-layered) to the surface of these elements of the electric transport system.…”