Track Circuit Research Articles

A novel approach in the measurement of high frequency disturbances from very large electrical systems

This paper demonstrates the feasibility of an interactive distributed measurement system having the capability of wireless triggering and time synchronisation for the purpose of detection, measurement and location of disturbances from very large electrical systems. System design, laboratory testing and preliminary site trials are discussed. Examples of how the system might be used are included. The first example relates to railway track circuit monitoring; the 2nd example relates to multi ended PD monitoring for insulated power cables; third example relates to radiometric partial discharge monitoring in substations and the last example relates to power quality monitoring and phasor measurements.

선로변 시설물의 지능적 제어를 위한 차상중심 열차제어시스템 시뮬레이션 기반 성능 평가

열차운행의 효율성 및 안전성 향상을 위해, 철도 제어시스템은 연동장치 등의 지상설비를 기반으로 한 지상중심의 제어시스템에서 ICT기술이 접목되어 지능적인 제어가 가능한 차상중심 제어시스템으로 진화하고 있다. 이러한 ICT기반 차상중심 열차제어시스템의 도입으로 선로변에 위치한 시설물들이 간소화되어 효율적이고 경제적인 제어시스템의 구현이 가능하다. 본 논문에서는 이러한 차상중심 열차제어시스템의 적용가능성을 평가하기 위해 차상 및 지상 제어장치의 시제품을 제작하고 선로전환기, 건널목 차단기 등 기존 선로변 시설물들을 이용하여 테스트 베드를 구축하였다. 또한, 열차운영 시나리오를 작성하여 통합 운영 시뮬레이션을 수행하였다. 시뮬레이션 결과는 열차 운행 시 요구되는 차상중심 제어시스템의 시험 항목들을 모두 만족시켰으며, 이를 통하여 제안된 ICT기반 차상중심 열차제어시스템의 유효성이 검증되었다. To improve the efficiency and safety of railway systems, the train control system has considerably evolved from the ground-equipment-based control system (e.g. track circuit, interlocking system, etc.) into the on-board-equipment-based control system. In addition, this train control system enables the rolling stock to intelligently control the trackside facilities by introducing information and communication technologies (ICT). Accordingly, since the ICT-based train control system simplifies the railway system (i.e. the heavy ground-equipment can be removed), an efficient and cost-effective railway system can be realized. In this paper, we perform a feasibility test of the ICT-based train control system using a simulation. To this end, we implement a test-bed consisting of prototype machines of on-board/ground equipment and introduce an integrated operation scenario for the train control. The simulation results satisfy all the requirements of train operation according to the scenario and show the effectiveness of the proposed train control system.

통합형 전자폐색제어장치의 적합성 확인을 위한 현장시험

열차를 안전하면서도 신속하게 운행하기 위해서는 항상 선행열차와 후속열차가 일정한 간격을 유지하면서 운행하여야 한다. 이를 위해 일정한 간격의 폐색구간을 설정하고, 열차의 안전운전을 위해 단일 폐색구간에는 1대의 열차만이 운행될 수 있도록 제어하는 폐색시스템이 필수적으로 요구된다. 기존의 폐색시스템은 신호기에 신호를 현시하는 계전기 방식의 자동폐색장치(ABS: Automatic Block System)로 구성되며, 이것은 연동장치를 통해 궤도회로 등선로변 장치들과 연동된다. 연동장치의 경우 국산 전자연동장치로 교체되고 있지만, 폐색장치는 여전히 아날로그 방식의 계전기 형태를 사용하고 있으며, 다른 선로변 장치들과 독립적으로 설치된다. 따라서 기존의 폐색장치는 건설과 유지보수 측면에서 많은 문제점을 가지고 있다. 또한 현재 국내 기존선에 사용되고 있는 ABS와 선로변 전자장치(LEU: Lineside Electronic Unit)는 동일한 장소에서 동일한 신호 정보에 의해 열차를 제어하고 있음에도 불구하고 별개 시스템으로 분리되어 설치되기 때문에, 각 제품의 단가 및 유지보수 비용 측면에서 효율적이지 않다. 따라서 본 논문에서는 기존 폐색장치인 ABS에 통신 및 디지털 전자 기술을 접목시킨 통합형 전자폐색제어장치(integrated electronic block system)와 그것의 현장시험 결과를 소개한다. 현장시험은 1월초부터 8월말까지 8개월간 총 8번의 주기점검을 통해 시행하였으며, 이를 통해 개발된 전자폐색장치의 유효성과 적합성을 확인하였다. For trains to run safely and quickly, the train should always follow the preceding train at a proper spacing. For this purpose, a certain distance between the stations is set for each block section. For the safe operation of trains in one block section, only one train service for an automatic block system is needed. The existing block system is composed an ABS, which is a linked track circuit and line sideway system through the interlocking system. The interlocking system is being replaced with a domestic electronic interlocking system. On the other hand, the block system still uses the relay format of an analog system, and is independently installed of the line sideway systems. Therefore, the existing block system has many problems in terms of construction and maintenance. In addition, the existing domestic line is used for ABS and LEU , which is installed separately, despite the train being controlled by the information of the same signal at the same location. This is not efficient in terms of each product price and the maintenance costs. This paper introduces an integrated electronic block system and the field test results. The field test was carried out through a periodic inspection performed eight times from January to late August.

Improving the stability of tonal track circuits under fluctuations of ballast resistance

Purpose.The purpose of investigation is the development of method for improving the stability of tonal track circuits that takes into account the actual insulation resistance (ballast resistance) of rail line.Methodology. To achieve the research purpose it was proposed to automatically determine the insulation resistance of rail line, and depending on this value to adjust the output voltage of track generator. Ballast resistance is determined by the value of input resistance the rail line, which at high frequencies practically is equal to the wave impedance. To implement the proposed method it is necessary to connect to the track circuit additional high-frequency generators, high-frequency filters, unit for finding the ballast resistance and adjusting the output voltage of track generator. Findings. As a result of research it was found that at low values (less than 2 Ohms*km) the change of ballast resistance causes significant change of voltage at the track receiver input, which may cause malfunction of the track circuit. Increasing the length of rail line leads to the reducing of its input resistance, raising the measuring frequency causes increasing the input resistance. In both cases, the input resistance tends to the value of the wave impedance. The measuring frequency should be chosen taking into account the length of rail line and the upper limit of ballast resistance, the value 5 Ohms*km can be taken as that limit. At higher values of ballast resistance its changes insignificantly influence the input voltage of track receiver. In this case, the adaptive adjustment of voltage at the track generator output is not performed. Originality. The method for measuring the insulation resistance of rail line has been improved that allows one to determine the ballast resistance automatically. The dependence between measuring frequency, length of rail line and ballast resistance have been determined. Practical value. The proposed method allows one to improve the reliability of tonal track circuits, to provide their stable operation under fluctuations of ballast resistance due to determination of the actual insulation resistance of rail line and the adaptation of track circuits to the actual conditions of their operation.

Track Circuit Failures: Their Impact on Conventional Signaling in CBTC Projects

Communication-based train control (CBTC) technology is the most advanced type of train control for urban transit systems. Unlike older train control technologies, CBTC systems do not require track circuits to detect trains on the tracks. However, in almost all CBTC projects, track circuits continue to be used for several reasons. It is possible to combine CBTC technology and track circuit equipment to improve the safety of all trains operating on the line. Trains can benefit from this combination of technologies whether they are equipped with CBTC equipment or not.

직류 자기장 변화를 이용한 새로운 열차검지기법 연구

The reason of train location detection is generally the train interval control between the railway stations and the train path control in the railway station yard in order to avoid train collision. It is very important to know the train location for shortening the train headway, and improving the efficiency of railway maintenance as well as the safe operation of trains. Therefore, the accurate detection of train location is the prerequisite technology in railway signalling system. The track circuit and the wheel sensor of rolling stock have been used to detect the train location widely in urban railway as well as high speed train. The track circuit is continuously monitored by electrical equipment to detect the absence of the train and the tachometer and encoder is used for the wheel sensor to measure the train speed. But speed sensor failures are frequent due to the extremely harsh operating conditions encountered in rail vehicle. The CBTC(Communication based Train Control) system has been used in urban railway system recently. But the installation of CBTC system is very high and the modification of design is difficult. This paper deals with the feasibility of new train location detection method using magnetic sensors.

실시간 모니터링을 통한 레일절손 검지에 관한 연구

Train accidents can be directly connected to fatal accidents-collision, derailment, Fire, railway crossing accidents-resulting in tremendous human casualties. First of all, the railway derailment is not only related to most of railway accidents but also it can lead to much more catastrophic accompanying train overtured than other factors. Therefore, it is most important factor to ensure railway safety. some foreign countries have applied to the detector machines(e.g., ultrasonic detector car, sleep mode, current detector, optical sensing, optical fiber). Since it was developed in order to prevent train from being derailed. In korea, the existing track method has been used to monitor rail condition using track circuit. However, we found out it impossible for Communication Based Train Control system(CBTC), recent technology to detect rail condition using balise(data transmission devices) without no track circuit. For this reason, it is needed instantly to develop real-time monitoring system used to detect broken rails. Firstly, this paper presents domestic and international statues analysis of rail breaks technology. Secondly, the composition and the characteristics of the real-time monitoring system. Finally, the evidence that this system could assumed the location and type of broken rails was proved by the experiment of prototype and operation line tests. We concluded that this system can detect rail break section in which error span exist within<TEX>${\pm}1m$</TEX>.

Investigation of transient processes in tonal track circuits

Purpose.The purpose of investigation is the search for new analysis methods of tonal track circuits, the definition of signal waveform at the track receiver input. Methodology. The method of frequency characteristics was used for investigation of transient processes. Signal spectrum at the output of track generator was determined using fast Fourier transform. Signal spectrum at the input of track receiver was calculated after determining complex frequency characteristic of the tonal track circuit. To carry out such calculations the frequency characteristics of rail line parameters have been obtained resulting interpolation of reference data and the frequency characteristic of track receiver impedance has been calculated. To determine the signal time dependence at the input of track receiver the inverse fast Fourier transform was applied.Findings. The causes of signal distortion in the tonal track circuits have been clarified.Track filter and input filter of track receiver restrict upper and lower sidebands of the signal spectrum, which leads to prolonging the rise and fall of signal pulses.The rail line, cable lines, and the devices for protection and alignment do not affect the shape of signal pulses, and change only their amplitude. At influence of rise and fall of signal pulses in the connected RLC circuits of receiver arise free oscillations at the resonance frequencies. As a result of the interference of these oscillations occur beats and appears additional pulse. Originality. The method for the analysis of tonal track circuits has been improved that allows determining not only the level but also the time dependence of signal at the track receiver for any input action. Practical value. Obtained time dependence of signal at the track receiver input will be useful in the development of the new more perfect methods for determining the state of tonal track circuit. Proposed method of track circuit analysis may be used to search for new more informative form of signal current.

Variability and uncertainty of Track Circuit band-pass modeling for interference evaluation

When evaluating track circuits (TC) interference, the latest normative approach indicates the use of band-pass filters that emulate the TC receiver response. The rms value of the output, when compared to the interference limit, indicates whether a specific signal might create interference or not. The implementation of the filter has some degrees of freedom and needs thus to be characterized in terms of added uncertainty to the interference evaluation process. The latter is relevant to safety, strictly related to the incorrect assignment of the status of the track section monitored and protected by the TC itself. When giving a definitive answer about the immunity of a specific TC and the compatibility with the tested rolling stock, it is thus necessary to completely evaluate the uncertainty associated to the chosen model and to the related signal processing operations, even if - it is recognized - their influence may be considered of second order with respect to infrastructure and rolling stock non-idealities.

A 1.25Gsps 0.35um SiGe BiCMOS Track and Hold Circuit

In this paper, a novel track and hold circuit in 0.35um SiGe BiCMOS process is presented. Compared to the traditional one, several improvements are made on the proposed track and hold circuit. At first, multistage architecture is used, which has better isolation. Secondly, a saturation protection circuit is designed into the track and hold circuit to prevent the NPN transistor from getting into saturation state. The simulation results show that the proposed track and hold circuit has a SFDR of 82dB and SNR of 76dB at the sampling rate of 1.25Gsps. Further simulation proved that the proposed track and hold circuit has better performances than the traditional one.

Communication Study in Track Circuit System in One Line in Shanghai Metro

This paper introduces the signal data acquisition method of the FSK signal using NI equipment in the track circuit system, and the FSK signal modulation demodulation based on LabVIEW . The track circuit communication detection device for Shanghai metro line 2 provided effective means, saved maintenance costs, created the economic benefit and laid the foundation for subsequent signal detection. solved the problem that without special equipment detection in wayside, it can also realize the results of detection intuitively and the quantitative analysis of technical index

Development and performance analysis of a novel impedance bond for railway track circuits

The ZPW-2000 track circuit is the dominant track circuit system used in China. On standard plain line track it is used as a jointless track circuit where ‘tuned zones’ are used to separate adjacent tracks operating at different frequencies. Owing to the complexities of station layouts it is not possible to use the ZPW-2000 as a jointless track circuit within stations, so a solution incorporating mechanical joints is commonly used. The station environment is known to have high levels of electromagnetic interference, and such environments can cause interference in the track circuit resulting in signal degradation and failure. An integrated solution that allows the ZPW-2000 track circuit to be used dependably in jointed operation that is able to cope with the electromagnetic environment found in stations is therefore required. In this study, a solution based on impedance bonds is developed to alleviate interference problems with the ZPW-2000 in harsh electromagnetic environments. The study presents an innovative design of impedance bond incorporating an air gap transformer and a double function filter circuit. The impedance bond was found to have an impedance of below 0.01 Ω at the resonant frequency of 50 Hz, and in excess of 17 Ω at other signal frequencies. The impedance bond is shown to eliminate interference while meeting the requirements of signal transmission on rail tracks. In this study, both theoretical analysis and the results of laboratory tests are presented.

A Novel Pre-Amplifier for DTH in Folding and Interpolating ADC

A pre-amplifier for distributed track and hold (DTH) circuit in high speed and high resolution folding and interpolating analog-to-digital converter (ADC) is proposed. This scheme resolves several limitations of conventional differential difference pre-amplifier (DDPA) in low voltage supply, compared to the conventional DDPA, the proposed scheme increases the input range so that all DDPAs of DTH can operate effectively, improves the averaging effect of average network, saves the random offset voltage from device mismatch, decreases the gain error of DTH, reduces the output common-mode (CM) deviation of DTH, and enhances the CM rejection of DTH. Based on SMIC 0.18μm CMOS technology and 1.8V power supply, over the input range, results from spectre shows dummy DDPAs of DTH operate effectively, the offset of output CM voltage of DTH decrease to less than 2mV, gain error decrease to less than 1%, the gain of middle novel pre-amplifier and boundary novel pre-amplifier are both 2.5, bandwidths are all above 1.9GHZ, while power dissipation of each DDPA is 3.22mW. The high CM rejection and low gain error decrease the quantification error effectively, and enhance the performance of ADC. The design meets the requirement of ADC applied to software defined radio (SDR).

The effect of friction modifiers on wheel/rail isolation at low axle loads

Signalling block occupancy is triggered by the wheelset of a rail vehicle ‘shunting’ the track circuit. The main cause of loss of shunting is the many materials that can be present on the rail head. These include iron oxides, leaves, ballast dust, oil, as well as products deliberately applied to the rail/wheel such as grease, friction modifiers, lubricants and sand. These may lead to an indication that a signal block is unoccupied when a train is actually present. Friction modifiers (FMs) are being increasingly used for reduction of noise, lateral forces, wear, rolling contact fatigue, etc. The Kelsan® high positive friction (HPF) solid stick FM is applied directly to the wheel tread creating a thin film. Although no effects have been observed during field operation, the intention in this work was to build on previous studies and evaluate conductance across a wider range of contact conditions as studies have shown that loss of shunt is more common with light axle loads where films could have a greater effect. The testing was performed at a contact pressure of 470 MPa (equating to a 4.9 tonne axle load). An HPF stick was spring loaded against the rotating wheel disc to generate a FM film at the contact. Tests were run to measure the impedance across the discs using a modified TI21 track circuit. Static testing was also performed using discs with a pre-generated HPF film. Analysis of the results showed that the application of HPF friction modifier had no significant effect on the measured level of impedance. The highest impedance levels were recorded under pure rolling (0% slip) where FMs were not being applied. In cases where the application of FM increased impedance, the recorded impedance values were still lower than the highest values measured in the absence of a FM. This is of key relevance as several light rail operators coast their trains.

ITX 차량 운행에 의한 AF 무절연 궤도회로의 귀선전류 영향 분석

Depending on the operating characteristics, track circuit is installed for the purpose of control directly or indirectly of the signal device, point switch machine and other security device. These are mainly used for train detection, transmission of information, broken train detection and transmission of return current. Especially, the return current is related to signal system, power system and catenary line, and track circuit systems. It is one of the most important component shall be dealt for the safety of track side staff and for the protection of railway-related electrical system according to electrification. Therefore, an accurate analysis of the return current is needed to prevent the return current unbalance and the system induced disorder and failure due to an over current condition. Also, if the malfunction occurred by the return current harmonics, it can cause problems including train operation interruption. In this paper, we presented measurement and analysis method at return current and it"s harmonics by train operation. By the test criteria, we evaluated for safety. Hereafter, it is expected to contribute to the field associated with it.

하이브리드 궤도회로를 이용한 지하철 정위치정차에 대한 연구

본 논문에서는 하이브리드 궤도회로를 이용한 정위치 정차시스템에 대한 가능성에 대해 연구하였다. 하이브리드 궤도회로는 UHF대역의 RFID시스템을 이용하고 실시간 운영체제를 기반으로 철도차상시스템과의 통신이 가능한 차세대 철도신호시스템의 한 부분이다. 본 논문에서 사용된 UHF대역 RFID 시스템은 원형편파의 태그와 리더 안테나가 사용되고 일체형 리더기는 송신출력 25dBm에서 우수한 인식회수를 얻었다. 현재 수동운행중인 지하철 차량에 이 시스템을 적용하여 정위치 정차를 하게 되면 기존 수동운전에서 기관사의 실수로 역을 지나거나 PSD(Platform Screen Door)와 열차출입문이 Mismatch 되는 현상을 방지할 수 있다. We have studied on the possibility of precise positioning using hybrid Track Circuit system. Hybrid Track Circuit uses RFID which replaces UHF. Hybrid Track Circuit is a part of next generation railroad signal system which is available to communicate with a railway on board system based on a realtime operating system. If applicate on a current hand operating subway, phenomenon caused by driver's mistake such as passing a stop without stopping or mismatch error between PSD and train door should be prevented.

A fault diagnosis method for the tuning area of jointless track circuits based on a neural network

This paper proposes a fault diagnosis method for the tuning area of jointless track circuits (JTCs) that is based on using a neural network. Based on the basic structure and working principle of a JTC and track circuit reader (TCR), the induced voltage amplitude envelope (IVAE) in a TCR under different typical fault modes of the tuning area is modelled using transmission line theory. Then, a quadratic function is used to implement piecewise fitting to the IVAE between the tuning area at the sending end of the track circuit and the fourth compensation capacitor counted from the sending end, for fault feature extraction. On the basis of the feature extracted, a back propagation neural network is constructed and trained for fault diagnosis of the tuning units. Experiments with real data show that this method has many advantages such as high detection accuracy, good adaptability and a wide applied range, etc. It can overcome the disadvantages of the current detection methods in aspects such as detection cost and timeliness. Furthermore, it also improves the safety and efficiency of train operation.

Train Detection by Magnetic Field Measurement with Giant Magnetoresistive Sensors for High-Speed Railway

Train detection, as part of the railway signaling system, is important for safe operation of high-speed railway. The recent flourishing development of high-speed railway stimulates the research need of train detection technology to enhance the safety and reliability of train operation. This paper proposes a new technique for train detection through magnetic field measurement by giant magnetoresistive sensors. This technology was studied by the analysis of magnetic field distribution in the high-speed rail system obtained from modeling and simulation. The results verify the feasibility for detection of train presence, number of rolling stocks, speed, and length. It can overcome the limitations of track circuits and provide additional measurement capabilities to the signaling system. This detection system can be built with low cost and minimal maintenance load as well as compacted construction. Therefore, it may serve as a new train detection system to help improve the current systems, enhancing and promoting the safety and reliability of high-speed rail system.

AF궤도회로에서 전기적 절연구간의 길이에 대한 연구

The electrical separation joint as a filter circuit distributes the track circuit frequency. The electrical separation joint is classified into the interval where reinforcing bars are insulated and not insulated through the length of track circuit. In case of incorrectly setting up the length of electrical separation joint, the amplitude of current on the track circuit is not over standard current which is the standard of current on the track circuit and it effects on the close frequency on track circuit. Then, it makes an accident or makes a train not receive information for train control. In this paper, the electrical separation joint model is suggested and parameters are numerically calculated in the model. Moreover, the length of electrical separation joint is analyzed and is demonstrated by uisng Matlab and PSpice program.

INDUCTION COUPLING BETWEEN JOINTLESS TRACK CIRCUITS AND TRACK-CIRCUIT-READER ANTENNA

This paper presents herein experiments and calculations of electromagnetic induction between jointless track circuits (JTCs) and track-circuit readers (TCRs). The paper uses transmission-line theory to simulate JTC currents ahead of shunt points and electromagnetism to calculate voltages induced in the TCR antenna. Based on these calculations, the JTC-to-TCR range is deflned. The paper derives expressions for the amplitude and phase of the voltage induced in the TCR antenna by the JTC current and uses them to quantitatively analyze the train control system. Experiments verify the conclusions reached based on the calculations.