A Novel Harmonic Suppression Traction Transformer with Integrated Filtering Inductors for Railway Systems

Abstract

This study analyzes and evaluates the feasibility of a harmonic suppression traction transformer (HSTT) for harmonic reduction in railway systems. This new type of transformer can improve the power quality of railway systems by preventing high-frequency harmonic currents from injecting into the traction grid. As the physical size of available space in high-speed trains is strictly limited, low space-occupying filtering techniques are needed. Therefore, an HSTT with integrated filtering inductors (IFIs) capable of being implemented in regular trains is proposed. Taking advantage of the HSTT, a specially constructed inductive-capacitive-inductive (LCL)-type filter is used for harmonic suppression instead of a regular LCL-type filter. The proposed filter is composed of an integrated inductor, leakage inductor of the traction transformer, and an external filter capacitor. In this paper, we analyze the topology of the proposed system, construct a mathematical model to reveal the magnetic decoupling theory of IFIs, and discuss the design and calculation procedures of the HSTT with IFIs. The field circuit coupling simulation of the HSTT with IFIs is performed to validate the effectiveness of the proposed system. Finally, the practical operation based on a 10 kVA prototype shows that the proposed scheme can not only suppress the high-order frequency harmonics but also decrease the installed space of filter devices.

Detection of Harmonic Overvoltage and Resonance in AC Railways Using Measured Pantograph Electrical Quantities

“…As HFOs are caused by the resonance of TPS and the line while accounting for distributed and lumped capacitance terms, and are excited by rolling stock emissions, two approaches may be identified for harmonic and resonance suppression: ground-based suppression and on-board suppression [9]. Among ground-based suppression techniques, use of passive and active filters installed at TPSs is the most common solution [30], although some network's reconfigurations may also be considered in order to shift the resonance frequency and reduce the factor of merit. On-board suppression may be achieved by installing passive filters, which may be exposed to excessive stress when an entire line section with resonance excited by nearby trains occurs [9].…”

“…In fact, this work discusses practical conditions for detection of resonance conditions from a railway vehicle perspective, using information available at the pantograph electric interface. Other measurement techniques have been proposed in the past [9,30,32], using purposely developed equipment located at TPS. The focus here instead is on the observability of resonance phenomena from the pantograph interface, to provide a distributed monitoring system that can be, in principle, installed onboard all the trains of the network.…”

Detection of Harmonic Overvoltage and Resonance in AC Railways using Measured Pantograph Electrical Quantities

“…As HFOs are caused by the resonance of TPS and line, accounting for distributed and lumped capacitance terms, and are excited by rolling stock emissions, two approaches may be identified for harmonic and resonance suppression: ground based suppression and on-board suppression [9]. Among ground based suppression techniques, use of passive and active filters installed at TPSs is the most common solution [29], although some networks reconfigurations may also be considered, in order to shift the resonance frequency and reduce the factor of merit. On-board suppression may be achieved by installing passive filters that may be exposed to excessive stress when an entire line section with resonance excited by nearby trains occurs [9].…”

“…This work discusses in fact practical conditions for detection of resonance conditions from a railway vehicle, using information available at the pantograph electric interface. Other measurement techniques have been proposed in the past [9,29,31], using purposely developed equipment located at TPS. The focus here instead is on the observability of resonance phenomena from the pantograph interface, to provide a distributed monitoring system that can be in principle installed onboard all the trains of the network.…”

A Harmonic Impedance Identification Method of Traction Network Based on Data Evolution Mechanism

“…Thus, the harmonic problem, a huge impact on the normal operation of trains, is a hidden danger to the security of RESs. Based on the above, proper harmonic suppression [7,8] and good matching characteristics of the harmonic impedance [9] are the key to improving harmonic problems and power quality [10,11], while the harmonic impedance of the traction network is an important parameter.…”