An Analysis Approach for Condition Monitoring and Fault Diagnosis in ...
2013 IEEE International Conference on Systems, Man, and Cybernetics
An Analysis Approach for Condition Monitoring and Fault Diagnosis in Pantograph-Catenary System Ebru Karaköse
Muhsin Tunay Gençolu
Department of Electrical-Electronics Engineering Frat University Elaz, Turkey [email protected]
Department of Electrical-Electronics Engineering Frat University Elaz, Turkey [email protected]
Abstract— High-speed trains have a great importance for long distances. The electrical energy for trains must be continuous and uninterrupted. So, the interaction and the mechanical contact between the pantograph and the catenary must be complete. Periodic condition monitoring, fault detection and pre-estimation are extremely important in the electrical railway systems. Therefore, in this study; a condition monitoring and fault diagnosis approach for pantograph- catenary system is proposed with improved model, control and analysis methods. There are two main aims of the study. The first is a regular monitoring of the system to determine whether any failure is occur. The second is to reveal the status of fault occurrence in the future. For this purpose, the contact point analysis between the pantograph strip and the catenary is performed. The most wearied points of the pantograph strip are defined by the method of condition monitoring. Keywords-pantograpjh; catenary;wear; condition monitoring; fault diagnosis
I.
INTRODUCTION
Technological development of electric railway systems and high-speed rail systems are proceeding very well for a long time over the world. The compatibility between the pantograph and the catenary is one of the most important issues. The pantograph moves and the catenary is fixed. And they are two very complex dynamic systems. Therefore, if there is a contact between them it makes the system more complex and analysis of this system is becoming difficult. The energy flow between pantograph-catenary (PAC) system and train is achieved by transmitting the energy to electrical traction vehicles of the train received through the pantograph from the catenary’s contact wire. It is important to have continuous energy. The quality of the contact force also shows the current collecting quality and quality of the interaction between them. The quality of the contact force depends on the amplitude of the applied force, the operating speed and the vibrations as a result of the contact between the pantograph and the catenary. Very low contact force leads to the formation of arc. An extremely high contact force causes wear at pantograph contact strip and catenary. In addition, increasing the abrasion of the contact wire or the pantograph strip leads to the arc. The necessary measures should be taken to reduce wearing so that maintenance costs will be reduced as well as the service life of the used equipment will be extended. If an extreme lifting force 978-1-4799-0652-9/13 $31.00 © 2013 IEEE DOI 10.1109/SMC.2013.337
is applied to the pantograph, there will be an intense contact and even the pantograph will remove the contact wire. This will result with terrible harm in pantograph and catenary and will cause oscillations [1-4]. Some of the problems comprised in railway transportation systems and their solution methods are available. Pantograph horizontal direction, equilibrium in this direction and active control of the contact force applied by pantograph to the catenary are a few of the most important problems occurred in railway systems. If the interaction is not proper between the pantograph and the catenary, the contact and the energy of the train can cut off or catenary can damage. Vibrations of the contact wire and external forces cause changing in force. This generates losses and instability in the system [5,6]. The general scheme of the PAC system for a railway line is shown in Fig. 1. The most prominent parts in this scheme are the pantograph and the catenary, but all components have different significance for system. Many studies have been achieved by examining the pantograph and catenary systems and failures that may occur in these systems [7,8]. Pombo [9] focused on the using of the multiple pantographs in this study. When there was a fault in one of the pantograph, the availability of using the second pantograph was investigated. The effects of environmental degradation was tried to show on the PAC system and finite element method was used for modeling. Xiaodong [10] was performed a self adaptive active control by applying to the suspension system of the PAC system to reduce vibrations. Ocoleanu [11] was used thermal analysis method to examine the interaction between the pantograph and the catenary. The temperature of contact point was experimentally measured for different current values with infrared camera. In [12] the mechanical structure of the pantograph and catenary system and the resonance event at different speeds with double pantograph were investigated. The required software formed with considering the non-linear pantograph analysis. The wear arising from friction and arc formation was analyzed in the laboratory environment, energized situation and different speeds. The effects of factors comprised the wear and their comparisons were presented in [13]. Wang [14] improved a new test device for a flexible contact action. Arrangements were made for the static contact resistance and tried to minimize it.
1963
the faults can occur especially at high speeds, pantograph breakage can be composed in interaction with fixed contact wire. In order to avoid this problem, tries to reduce the sagging of the contact wire and various structures are designed to create a flexible structure [15, 16]. A wide variety of failures can be encountered in such systems. The contact between the pantograph and the catenary is also need to be in a particular region on pantograph surface. The contact may not be in particular region because of some reasons. These reasons can be sourced by;
Figure 1. Pantograph and catenary system for a railway line
In this study; condition monitoring and fault diagnosis methods of PAC system are presented with improved modeling and analysis methods and additional methods. There are two main aims of the study. The first is a regular monitoring of the system to determine whether any failure is occur. The second is to reveal fault occurrence status in the future. For this purpose, the contact point analysis between the pantograph strip and the catenary is performed. There are two approaches here. Primarily, the situation of the contact wire touching to the ends of the pantograph is controlled. Because if it touches the ends of the pantograph that can cause serious faults. Then, the most touched points of pantograph strip to the catenary line are analyzed and statistical data are obtained. Thus, the most wearied points of strip are determined by the method of condition monitoring. II.
• rail or ground. A breakdown of rail or ground affects the interaction between the pantograph and the contact wire. If the train cannot move forward the contact is always happen at the same point. The supporter and rail mounting must be appropriate practiced where the ground is very hilly. • catenary. Good setting of catenary stiffness and sagging is required. • pantograph. In particular, as the speed increases irregularities or a very small crack on the surface of the pantograph raises the serious problems. • weather conditions. These systems are affected from adverse weather conditions, because they are generally operated in outdoor. The effects such as extreme heat or cold, windy weather and ice load can disrupt the system’s normal structure.
ANALYSIS OF THE PAC SYSTEM
Due to the technical characteristics of the passive pantographs, the renewal or editing operations cannot be made. The modeling is becoming more difficult with increasing the speed of the system. The adaptation to different catenary structures and working conditions can be achieved with activecontrolled pantograph and also the changes in the contact force can be controlled. Thus, the contact force variations can be reduced, the technical and mechanical problems can be prevented and the requirement for expensive measurements and maintenances can be decreased. To reduce the occurred problems and the costs of the system, the interaction between pantograph and catenary should be the most appropriate way. While the model is developing, maintaining the constant contact force variation must be targeted [2, 17, 18].
Different methods can be used for collecting of electrical energy to the train in electrical railway systems, for example from overhead line, rail, but the most dependable way is PAC system [11]. Catenary is a system that is formed with wires and other components and it is in contact with the pantograph to provide electrical energy of the system. Catenary system provides the required energy from the centers of the transformer buildings at regular intervals along the railway line. If the damping is lower in the system, catenary oscillations will occur and they will not only occur around the point of contact. And they will also cause other problems. The wave propagation comprises all catenary. The elements of a simple catenary can be represented by wires, insulators, dropper, supports, etc. Each of these requires a different modeling. Catenary can be formed as stitched catenary and compound catenary. And their structure and analysis is different from each other.
In order to realize the required simulation, electrical railway system needs to be analyzed step by step in detail. The establishment of such systems is very difficult and expensive. Due to environmental conditions or unexpected effects, undesirable diagnosis may occur and these faults may lead to accidents or interruption of operation. So, it is necessary to optimally use and evaluate the existing systems. Periodic monitoring, fault detection and pre-estimation of the required maintenance of the railway systems in the World are extremely important. Monthly checks of the railway systems are made with no interruptions in many countries. Basically, controls focus on two fundamental points, these are monitoring of rail profile and catenary line. When examining situations such as wear of rails, breaking, twisting, catenary line tension, the contact situation, the compatibility of the pantograph axis with catenary line, the factors that prevent accidents will be tried to pre-determine [19,20].
System infrastructure is very important for high-speed railway lines. These systems either have been designed in accordance with their own structures or existing systems must be used with developing and accelerating. When considering a high speed traveling system and its distance at a second, the importance of receipting the uninterrupted energy is understood. Therefore, the system must be very well designed and manufactured to obtain the appropriate value of the contact force and the uninterrupted contact between the PAC systems or to avoid excessive contact. Contact wire flexibility and sagging are very critical in these systems. Contact wire is fixed on the supports at regular intervals; while it is close to the support point the flexibility of the wire is less, at the middle points of the wire the flexibility increases. In this case,
1964
III.
PROPOSED APPROACH
The points of the pantograph that touch to the contact wire are very important for this system. The vast majority of problems can occur due to the wear and deterioration on the surface of pantograph. The contact which is always at the same point of the pantograph is not reliable. Therefore, the pantograph surface is divided into specific regions and the situations that might occur for each region are mentioned. The block diagram in Fig. 2 is used to create the analysis approach model. After achieving the mathematical model of the contact point variation between the pantograph and catenary, the amount of contact is obtained and evaluated with the diagnosis algorithm.
(a)
The symbolic representation of the pantograph, the catenary and the pantograph parts affecting the contact are shown in Fig. 3. As shown in Fig. 3, three regions are defined for contact points on pantograph surface and circumstances of each region are examined. The regions are named by depending on the impacts of the contact. The first region of the pantograph is the fault region. This region corresponds to the horns and the ends of the pantograph and if any contact is realized in here, it leads to enormous damages. Breaking or rupture can occur on the pantograph and the catenary and contact can be cut off. The second region is dangerous region. This region is between the fault region and safe region. Having a contact in this region does not lead to big problems but it is an undesirable condition. The contact between the pantograph and the catenary is wanted to be in safe region and it is depend on the desaxement.
Figure 3. (a) The symbolic representation of the pantograph and the catenary (b) Pantograph regions
The catenary line is deported from the horizontal axis of the rail line for a particular value. This distance is called as desaxement and its value is 20 cm. Before the creation stage of the system, all arrangements are determined by considering this distance in the design stage. The positions of the supporters and their relationship, the distance between the supporter and the axis of the rail line, the length of the wire are adjusted with respect to the desaxement. And also, the desaxement is important because, the friction as a result of contact between the moving pantograph and the fixed contact wire must not always comprised in the same point on the surface of pantograph and the carbon wear should be uniform in order to avoid easily deformation. The location of the contact point variation according to the pantograph movement and desaxement is shown in Fig. 4. The horizontal movement of the pantograph basically depends on the speed of the train. And the vertical movement of it depends on the lifting force applied by the actuator to pantograph. In this study, it is assumed that the sufficient lifting force is applied to the pantograph and focused on horizontal movement of the pantograph.
Figure 2. The block diagram of the analysis approach
Figure 4. The variation of contact point
1965
In modeling stage, the mathematical model of the system is performed and the simulation is realized. According to the speed of the train and the time, the values of contact points of the pantograph are received from the model with condition monitoring methods. Fault diagnosis is accomplished with use of these values. After obtaining the necessary equations, the contact point variation depending on the pantograph movement is found according to the iteration step.
IV.
The proposed algorithm has been developed to avoid some problems of the PAC systems and to provide the possibility of early diagnosis in case of a fault. Periodic condition monitoring for the position of the contact point is required to determine the faults. This system is realized in Matlab environment to work more suitable in real-time. The condition monitoring is achieved for different speed values in simulation. 500 iteration steps are used for each of the speed value. The used system parameters are given in following,
(1) (2) (3) (4) Here, : The distance of the train, : The speed of the train, : The measuring step as second, : The distance between two supporters (that is the length of the span), : Desaxement, : The length of the pantograph, : The reference distance, These variables used in the equations and required to create the model shown in Fig. 5. The new location of the contact
,
and
,
The simulation is carried out by writing these values in equations in the previous section. The simulation results for different speed values are given in figures. And also it is observed that the desired outcomes are obtained. The simulation result for the speed value of 20 km /h is given in Fig. 6. This is a result of stable condition and the contact wire moves on the safe region. The axis of the rail line and the desaxement are shown in the figure. The axis of the rail line also shows the middle point of the pantograph. Contact point is ranging from ±20 cm according to the midpoint of the pantograph. In Fig. 7 and 8 represent the variation of the contact points when the speed value of the train is increased to 50 km/h and 200 km/h, respectively. The contact wire has not got a smooth form because of the desaxement it has got a zig-zag form, so the zig-zag movement of the pantograph is clearly seen in the figures. As the speed increases the contact point variation also increases. In case of the speed increases or decreases, problems are blocked by performing continuous condition monitoring. 1.6
value with the Contact points of pantograph
point is calculated by summing the value in each step of sampling.
SIMULATION RESULTS
1.4 1.2 1 0.8 0.6 0.4 0.2 0
0
100
200
300
400
500
Iteration steps Figure 6. The variation of contact points for the speed of 20 km/h
Figure 5. The required variables
1966
Contact points of pantograph
1.6
diagnostic algorithm, if the contact ratio in dangerous region is 5% or below it, there is no need to take any precaution and the condition is negligible. There is not a difference between the first and second scenarios in terms of energy requirement of the train. In both cases, the train can take the necessary energy properly. But, if the contact point’s ratio is above the ratio of 5% in the dangerous region, as in the scenarios of 4th and 6th, this might indicate a problem in the system due to the structural or external reasons. It should be evaluated and optimized immediately. In the scenarios of 3th, 5th, 7th and 8th the fault has already occurred, therefore the important thing is to stop the fault before reaching serious proportions and to determine what is the origin of the fault.
1.4 1.2 1 0.8 0.6 0.4 0.2 0
0
100
200
300
400
500
1000
1000
500
500
Iteration steps
0 1000
T h e n u m b e r o f c o n ta c t p o in ts
Figure 7. The variation of contact points for the speed of 50 km/h
Contact points of pantograph
1.6 1.4 1.2
500
0.8 0.6
0
1 2 3 4 5
500 0
1 2 3 4 5
500
0.2 100
200
300
400
500
0
1 2 3 4 5
1000
0
1 2 3 4 5
1000 500
0 0
1 2 3 4 5
1000
500
1000
0.4
0
500
1000
1
0
1 2 3 4 5
1 2 3 4 5
0
1 2 3 4 5
Regions of pantograph (1-5: Fault, 2-4: Dangerous, 3: Safe)
Iteration steps
Figure 9. The variation of contact points for eight random scenarios
Figure 8. The variation of contact points for the speed of 200 km/h
In addition, the simulation results have been obtained for the faulty and stable cases. The pantograph is always wanted to work in the safe region, the regions where the pantograph works are evaluated by analyzing the simulation results and the classification of the regions for contact point variation is realized with the diagnosis algorithm.
TABLE 1: CONTACT RATIOS IN PANTOGRAPH REGIONS FOR EIGHT SCENARIOS Contact ratios in pantograph regions (%)
The variation of the contact point’s regions is seen in Fig. 9 for eight random scenarios. The regions on the pantograph surface for 1000 contact points are observed. 1 and 5 correspond to the fault region, 2 and 4 are the dangerous region and 3 is the safe region. The contact point’s ratios on pantograph regions for eight random scenarios in the Fig. 9 are given in the Tab.1. The first scenario is 100% stable condition, there is no fault and the contact is on safe region in desaxement range. In the second scenario, the contact moves to the dangerous region but it is not at a bad level that will create problems and the contact ratio is 5%. According to the created
1967
Condition
Fault
Dangerous
Safe
1
0
0
100
2
0
5
95
3
1
20
79
4
0
18
82
5
2.2
22.8
75
6
0
33.5
66.5
7
27.5
41.5
31
8
11.5
65.5
23
CONCLUSION In this study, an analysis approach for condition monitoring and fault diagnosis in pantograph and catenary systems has been presented. The variation of contact points between the pantograph strip and contact wire for three speed values are given. The stable and faulty conditions are compared by examining with the developed diagnosis algorithm. The importance of the contact between pantograph and catenary in safe region is emphasized with obtained results. It is confirmed that the contact point is on the safe region in the stable condition and it passes to the fault region from the dangerous region in the fault condition. The contact can move to the dangerous region from the safe region for a short time due to the weather conditions, a temporary ground or rail disturbance or any reason. If this contact point’s variation in dangerous region is under the ratio of 5%, there is no problem and no need to take a precaution, it is a temporary condition and negligible. However, if the contact point’s variation is above the ratio of 5% and continues to increase, it is necessary to take precautions as soon as possible and preventing the passage of the contact to the fault region is required. Because, when a contact forms in fault region, it is almost impossible to avoid the problems. All of these show the importance of periodic condition monitoring for PAC systems. A problem can turn into a fault in the future so the pre-estimation and the resolution of it is important. In this way, the encountered faults in railway systems, pantograph and catenary damages and the cost of the system will be decreased. The amount of contacts in the end points of the pantograph and the wear of pantograph strip will be known. If a fault occurs, it will be identified and evaluations will be done. After determining the fault type, appropriate measures will be taken and the efficiency of the system will be increased. REFERENCES [1]
[2]
[3]
[4]
S. H. Kia, F. Bartolini, A. M. Mabwe, R. Ceschi, “Real-Time Simulation of Pantograph-Catenary Interaction,” 37th Annual Conference on IEEE Industrial Electronics Society IECON, pp. 258-264, 2011. E. Karakose, M. T. Gencoglu, “ Adaptive Fuzzy Control Aproach for Dynamic Pantograph Catenary Interaction”, MECHATRONIKA, 2012 15th International Symposium , pp.1-5, 2012 . I. Aydin, M. Karakose, E. Akin, “A New Contactless Fault Diagnosis Approach for Pantograph-Catenary System”, MECHATRONIKA, 2012 15th International Symposium , pp.1-6, 2012 . L. Zhou, Z. Shen, “Progress in High-Speed Train Technology Around The World,” Journal of Modern Transportation, vol. 19, no.1, pp. 1-6, 2011.
[5]
C. O'Donnell, R. Palacin, J. Rosinski, “Pantograph Damage And Wear Monitoring System”, The Institution of Engineering and Technology International Conference on Railway Condition Monitoring, 178 – 181, 2006. [6] Y. Zhang, Y. Qin, X. Cheng, L. Jia, Z. Xing, “An Analysis Method for the Correlation between Catenary Irregularities and PantographCatenary Contact Force,” Transportation Research Board Annual Meeting, 2012. [7] A. Basso, A. Collina, M. Galimberti, R. Sala, “Pantograph dynamic analysis by means of non-contact optical measurement techniques,” EVACES 2011 – Experimental Vibration Analysis for Civil Engineering Structures, pp. 553-560, 2011. [8] C. Nituca, “Thermal Analysis of Electrical Contacts from Pantograph– Catenary System for Power Supply of Electric Vehicles,”Electric Power Systems Research, vol. 96, 211– 217, 2013. [9] J. Pombo, J. Ambrosio, “Environmental and Track Perturbations on Multiple Pantograph Interaction with Catenaries in High-Speed Trains,” Proceedings of The Thirteenth International Conference on Civil, Structural And Environmental Engineering Computing, pp.1-14, 2011. [10] Z. Xiaodong, F. Yu, “Active Self-adaptive Control of High-speed Train Pantograph,” Power Engineering and Automation Conference (PEAM), Vol. 3, pp. 152 – 156, 2011. [11] C.F. Ocoleanu, I. Popa, G. Manolea, A.I. Dolan,S. Vlase, “Temperature Investigation in Contact Pantograph-AC Contact Line,” Internatonal Journal of Circuits, Systems And Signal Processing, vol. 3,pp. 154-163, 2009. [12] A. Bobillot, J.P. Massat, J.P. Mentel, “ Design of Pantograph-Catenary Systems by Simulation,” 9th World Congress on Railway Research(WCRR), 2011. [13] T. Ding, G. Chen, Y. Li, Q. He, W. Xuan, “Friction and Wear Behavior of Pantograph Strips Sliding aganist Copper Contact Wire with Electric Current,” AASRI Procedia, pp. 288-292, 2012. [14] W. Wang, A. Dong ,G. Wu, G. Gao, L. Zhou, B. Wang, Y. Cui ,D. Liu, D. Li, T. Li, “Study on Characterization of Electrical Contact Between Pantograph and Catenary,” Electrical Contacts (Holm), 2011 IEEE 57th Holm Conference on, pp. 1-6, 2011. [15] K. K. Ang, J. Dai, “Response Analysis of High-speed Rail System Accounting for Abrupt Change of Foundation Stiffness,” Journal of Sound and Vibration, vol. 332, pp. 2954–2970, 2013. [16] J. Ambrosio, J. Pombo, M. Pereira, “Optimization of high-speed railway pantographs for improving pantograph-catenary contact,” Theoretcal & Appled Mechancs Letters 3, 013006, 2013. [17] B. Allotta, L. Pugi, F. Bartolini, “Design and Experimental Results of an Active Suspension System for a High-Speed Pantograph,” IEEE/ASME Transactions on Mechatronics, Vol. 13, No. 5, pp. 548-557, October 2008. [18] R.J. Lian, “Enhanced Adaptive Self-Organizing Fuzzy Sliding-Mode Controller for Active Suspension Systems,” IEEE Transactions on Industrial Electronics, vol. 59, no. 12, 2012. [19] I. Aydin, M. Karakose, E. Akin, “ Artificial Immune Inspired Fault Detection Algorithm Based on Fuzzy Clustering and Genetic Algorithm Methods”, Computational Intelligence for Measurement Systems and Applications, CIMSA 2008, pp. 93-98, 2008. [20] G. Bucca, A. Collina, “A Procedure for The Wear Prediction of Collector Strip and Contact Wire in Pantograph–Catenary System,” Wear 266, pp. 46–59, 2009.
1968
An Analysis Approach for Condition Monitoring and Fault Diagnosis in Pantograph-Catenary System Ebru Karaköse
Muhsin Tunay Gençolu
Department of Electrical-Electronics Engineering Frat University Elaz, Turkey [email protected]
Department of Electrical-Electronics Engineering Frat University Elaz, Turkey [email protected]
Abstract— High-speed trains have a great importance for long distances. The electrical energy for trains must be continuous and uninterrupted. So, the interaction and the mechanical contact between the pantograph and the catenary must be complete. Periodic condition monitoring, fault detection and pre-estimation are extremely important in the electrical railway systems. Therefore, in this study; a condition monitoring and fault diagnosis approach for pantograph- catenary system is proposed with improved model, control and analysis methods. There are two main aims of the study. The first is a regular monitoring of the system to determine whether any failure is occur. The second is to reveal the status of fault occurrence in the future. For this purpose, the contact point analysis between the pantograph strip and the catenary is performed. The most wearied points of the pantograph strip are defined by the method of condition monitoring. Keywords-pantograpjh; catenary;wear; condition monitoring; fault diagnosis
I.
INTRODUCTION
Technological development of electric railway systems and high-speed rail systems are proceeding very well for a long time over the world. The compatibility between the pantograph and the catenary is one of the most important issues. The pantograph moves and the catenary is fixed. And they are two very complex dynamic systems. Therefore, if there is a contact between them it makes the system more complex and analysis of this system is becoming difficult. The energy flow between pantograph-catenary (PAC) system and train is achieved by transmitting the energy to electrical traction vehicles of the train received through the pantograph from the catenary’s contact wire. It is important to have continuous energy. The quality of the contact force also shows the current collecting quality and quality of the interaction between them. The quality of the contact force depends on the amplitude of the applied force, the operating speed and the vibrations as a result of the contact between the pantograph and the catenary. Very low contact force leads to the formation of arc. An extremely high contact force causes wear at pantograph contact strip and catenary. In addition, increasing the abrasion of the contact wire or the pantograph strip leads to the arc. The necessary measures should be taken to reduce wearing so that maintenance costs will be reduced as well as the service life of the used equipment will be extended. If an extreme lifting force 978-1-4799-0652-9/13 $31.00 © 2013 IEEE DOI 10.1109/SMC.2013.337
is applied to the pantograph, there will be an intense contact and even the pantograph will remove the contact wire. This will result with terrible harm in pantograph and catenary and will cause oscillations [1-4]. Some of the problems comprised in railway transportation systems and their solution methods are available. Pantograph horizontal direction, equilibrium in this direction and active control of the contact force applied by pantograph to the catenary are a few of the most important problems occurred in railway systems. If the interaction is not proper between the pantograph and the catenary, the contact and the energy of the train can cut off or catenary can damage. Vibrations of the contact wire and external forces cause changing in force. This generates losses and instability in the system [5,6]. The general scheme of the PAC system for a railway line is shown in Fig. 1. The most prominent parts in this scheme are the pantograph and the catenary, but all components have different significance for system. Many studies have been achieved by examining the pantograph and catenary systems and failures that may occur in these systems [7,8]. Pombo [9] focused on the using of the multiple pantographs in this study. When there was a fault in one of the pantograph, the availability of using the second pantograph was investigated. The effects of environmental degradation was tried to show on the PAC system and finite element method was used for modeling. Xiaodong [10] was performed a self adaptive active control by applying to the suspension system of the PAC system to reduce vibrations. Ocoleanu [11] was used thermal analysis method to examine the interaction between the pantograph and the catenary. The temperature of contact point was experimentally measured for different current values with infrared camera. In [12] the mechanical structure of the pantograph and catenary system and the resonance event at different speeds with double pantograph were investigated. The required software formed with considering the non-linear pantograph analysis. The wear arising from friction and arc formation was analyzed in the laboratory environment, energized situation and different speeds. The effects of factors comprised the wear and their comparisons were presented in [13]. Wang [14] improved a new test device for a flexible contact action. Arrangements were made for the static contact resistance and tried to minimize it.
1963
the faults can occur especially at high speeds, pantograph breakage can be composed in interaction with fixed contact wire. In order to avoid this problem, tries to reduce the sagging of the contact wire and various structures are designed to create a flexible structure [15, 16]. A wide variety of failures can be encountered in such systems. The contact between the pantograph and the catenary is also need to be in a particular region on pantograph surface. The contact may not be in particular region because of some reasons. These reasons can be sourced by;
Figure 1. Pantograph and catenary system for a railway line
In this study; condition monitoring and fault diagnosis methods of PAC system are presented with improved modeling and analysis methods and additional methods. There are two main aims of the study. The first is a regular monitoring of the system to determine whether any failure is occur. The second is to reveal fault occurrence status in the future. For this purpose, the contact point analysis between the pantograph strip and the catenary is performed. There are two approaches here. Primarily, the situation of the contact wire touching to the ends of the pantograph is controlled. Because if it touches the ends of the pantograph that can cause serious faults. Then, the most touched points of pantograph strip to the catenary line are analyzed and statistical data are obtained. Thus, the most wearied points of strip are determined by the method of condition monitoring. II.
• rail or ground. A breakdown of rail or ground affects the interaction between the pantograph and the contact wire. If the train cannot move forward the contact is always happen at the same point. The supporter and rail mounting must be appropriate practiced where the ground is very hilly. • catenary. Good setting of catenary stiffness and sagging is required. • pantograph. In particular, as the speed increases irregularities or a very small crack on the surface of the pantograph raises the serious problems. • weather conditions. These systems are affected from adverse weather conditions, because they are generally operated in outdoor. The effects such as extreme heat or cold, windy weather and ice load can disrupt the system’s normal structure.
ANALYSIS OF THE PAC SYSTEM
Due to the technical characteristics of the passive pantographs, the renewal or editing operations cannot be made. The modeling is becoming more difficult with increasing the speed of the system. The adaptation to different catenary structures and working conditions can be achieved with activecontrolled pantograph and also the changes in the contact force can be controlled. Thus, the contact force variations can be reduced, the technical and mechanical problems can be prevented and the requirement for expensive measurements and maintenances can be decreased. To reduce the occurred problems and the costs of the system, the interaction between pantograph and catenary should be the most appropriate way. While the model is developing, maintaining the constant contact force variation must be targeted [2, 17, 18].
Different methods can be used for collecting of electrical energy to the train in electrical railway systems, for example from overhead line, rail, but the most dependable way is PAC system [11]. Catenary is a system that is formed with wires and other components and it is in contact with the pantograph to provide electrical energy of the system. Catenary system provides the required energy from the centers of the transformer buildings at regular intervals along the railway line. If the damping is lower in the system, catenary oscillations will occur and they will not only occur around the point of contact. And they will also cause other problems. The wave propagation comprises all catenary. The elements of a simple catenary can be represented by wires, insulators, dropper, supports, etc. Each of these requires a different modeling. Catenary can be formed as stitched catenary and compound catenary. And their structure and analysis is different from each other.
In order to realize the required simulation, electrical railway system needs to be analyzed step by step in detail. The establishment of such systems is very difficult and expensive. Due to environmental conditions or unexpected effects, undesirable diagnosis may occur and these faults may lead to accidents or interruption of operation. So, it is necessary to optimally use and evaluate the existing systems. Periodic monitoring, fault detection and pre-estimation of the required maintenance of the railway systems in the World are extremely important. Monthly checks of the railway systems are made with no interruptions in many countries. Basically, controls focus on two fundamental points, these are monitoring of rail profile and catenary line. When examining situations such as wear of rails, breaking, twisting, catenary line tension, the contact situation, the compatibility of the pantograph axis with catenary line, the factors that prevent accidents will be tried to pre-determine [19,20].
System infrastructure is very important for high-speed railway lines. These systems either have been designed in accordance with their own structures or existing systems must be used with developing and accelerating. When considering a high speed traveling system and its distance at a second, the importance of receipting the uninterrupted energy is understood. Therefore, the system must be very well designed and manufactured to obtain the appropriate value of the contact force and the uninterrupted contact between the PAC systems or to avoid excessive contact. Contact wire flexibility and sagging are very critical in these systems. Contact wire is fixed on the supports at regular intervals; while it is close to the support point the flexibility of the wire is less, at the middle points of the wire the flexibility increases. In this case,
1964
III.
PROPOSED APPROACH
The points of the pantograph that touch to the contact wire are very important for this system. The vast majority of problems can occur due to the wear and deterioration on the surface of pantograph. The contact which is always at the same point of the pantograph is not reliable. Therefore, the pantograph surface is divided into specific regions and the situations that might occur for each region are mentioned. The block diagram in Fig. 2 is used to create the analysis approach model. After achieving the mathematical model of the contact point variation between the pantograph and catenary, the amount of contact is obtained and evaluated with the diagnosis algorithm.
(a)
The symbolic representation of the pantograph, the catenary and the pantograph parts affecting the contact are shown in Fig. 3. As shown in Fig. 3, three regions are defined for contact points on pantograph surface and circumstances of each region are examined. The regions are named by depending on the impacts of the contact. The first region of the pantograph is the fault region. This region corresponds to the horns and the ends of the pantograph and if any contact is realized in here, it leads to enormous damages. Breaking or rupture can occur on the pantograph and the catenary and contact can be cut off. The second region is dangerous region. This region is between the fault region and safe region. Having a contact in this region does not lead to big problems but it is an undesirable condition. The contact between the pantograph and the catenary is wanted to be in safe region and it is depend on the desaxement.
Figure 3. (a) The symbolic representation of the pantograph and the catenary (b) Pantograph regions
The catenary line is deported from the horizontal axis of the rail line for a particular value. This distance is called as desaxement and its value is 20 cm. Before the creation stage of the system, all arrangements are determined by considering this distance in the design stage. The positions of the supporters and their relationship, the distance between the supporter and the axis of the rail line, the length of the wire are adjusted with respect to the desaxement. And also, the desaxement is important because, the friction as a result of contact between the moving pantograph and the fixed contact wire must not always comprised in the same point on the surface of pantograph and the carbon wear should be uniform in order to avoid easily deformation. The location of the contact point variation according to the pantograph movement and desaxement is shown in Fig. 4. The horizontal movement of the pantograph basically depends on the speed of the train. And the vertical movement of it depends on the lifting force applied by the actuator to pantograph. In this study, it is assumed that the sufficient lifting force is applied to the pantograph and focused on horizontal movement of the pantograph.
Figure 2. The block diagram of the analysis approach
Figure 4. The variation of contact point
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In modeling stage, the mathematical model of the system is performed and the simulation is realized. According to the speed of the train and the time, the values of contact points of the pantograph are received from the model with condition monitoring methods. Fault diagnosis is accomplished with use of these values. After obtaining the necessary equations, the contact point variation depending on the pantograph movement is found according to the iteration step.
IV.
The proposed algorithm has been developed to avoid some problems of the PAC systems and to provide the possibility of early diagnosis in case of a fault. Periodic condition monitoring for the position of the contact point is required to determine the faults. This system is realized in Matlab environment to work more suitable in real-time. The condition monitoring is achieved for different speed values in simulation. 500 iteration steps are used for each of the speed value. The used system parameters are given in following,
(1) (2) (3) (4) Here, : The distance of the train, : The speed of the train, : The measuring step as second, : The distance between two supporters (that is the length of the span), : Desaxement, : The length of the pantograph, : The reference distance, These variables used in the equations and required to create the model shown in Fig. 5. The new location of the contact
,
and
,
The simulation is carried out by writing these values in equations in the previous section. The simulation results for different speed values are given in figures. And also it is observed that the desired outcomes are obtained. The simulation result for the speed value of 20 km /h is given in Fig. 6. This is a result of stable condition and the contact wire moves on the safe region. The axis of the rail line and the desaxement are shown in the figure. The axis of the rail line also shows the middle point of the pantograph. Contact point is ranging from ±20 cm according to the midpoint of the pantograph. In Fig. 7 and 8 represent the variation of the contact points when the speed value of the train is increased to 50 km/h and 200 km/h, respectively. The contact wire has not got a smooth form because of the desaxement it has got a zig-zag form, so the zig-zag movement of the pantograph is clearly seen in the figures. As the speed increases the contact point variation also increases. In case of the speed increases or decreases, problems are blocked by performing continuous condition monitoring. 1.6
value with the Contact points of pantograph
point is calculated by summing the value in each step of sampling.
SIMULATION RESULTS
1.4 1.2 1 0.8 0.6 0.4 0.2 0
0
100
200
300
400
500
Iteration steps Figure 6. The variation of contact points for the speed of 20 km/h
Figure 5. The required variables
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Contact points of pantograph
1.6
diagnostic algorithm, if the contact ratio in dangerous region is 5% or below it, there is no need to take any precaution and the condition is negligible. There is not a difference between the first and second scenarios in terms of energy requirement of the train. In both cases, the train can take the necessary energy properly. But, if the contact point’s ratio is above the ratio of 5% in the dangerous region, as in the scenarios of 4th and 6th, this might indicate a problem in the system due to the structural or external reasons. It should be evaluated and optimized immediately. In the scenarios of 3th, 5th, 7th and 8th the fault has already occurred, therefore the important thing is to stop the fault before reaching serious proportions and to determine what is the origin of the fault.
1.4 1.2 1 0.8 0.6 0.4 0.2 0
0
100
200
300
400
500
1000
1000
500
500
Iteration steps
0 1000
T h e n u m b e r o f c o n ta c t p o in ts
Figure 7. The variation of contact points for the speed of 50 km/h
Contact points of pantograph
1.6 1.4 1.2
500
0.8 0.6
0
1 2 3 4 5
500 0
1 2 3 4 5
500
0.2 100
200
300
400
500
0
1 2 3 4 5
1000
0
1 2 3 4 5
1000 500
0 0
1 2 3 4 5
1000
500
1000
0.4
0
500
1000
1
0
1 2 3 4 5
1 2 3 4 5
0
1 2 3 4 5
Regions of pantograph (1-5: Fault, 2-4: Dangerous, 3: Safe)
Iteration steps
Figure 9. The variation of contact points for eight random scenarios
Figure 8. The variation of contact points for the speed of 200 km/h
In addition, the simulation results have been obtained for the faulty and stable cases. The pantograph is always wanted to work in the safe region, the regions where the pantograph works are evaluated by analyzing the simulation results and the classification of the regions for contact point variation is realized with the diagnosis algorithm.
TABLE 1: CONTACT RATIOS IN PANTOGRAPH REGIONS FOR EIGHT SCENARIOS Contact ratios in pantograph regions (%)
The variation of the contact point’s regions is seen in Fig. 9 for eight random scenarios. The regions on the pantograph surface for 1000 contact points are observed. 1 and 5 correspond to the fault region, 2 and 4 are the dangerous region and 3 is the safe region. The contact point’s ratios on pantograph regions for eight random scenarios in the Fig. 9 are given in the Tab.1. The first scenario is 100% stable condition, there is no fault and the contact is on safe region in desaxement range. In the second scenario, the contact moves to the dangerous region but it is not at a bad level that will create problems and the contact ratio is 5%. According to the created
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Condition
Fault
Dangerous
Safe
1
0
0
100
2
0
5
95
3
1
20
79
4
0
18
82
5
2.2
22.8
75
6
0
33.5
66.5
7
27.5
41.5
31
8
11.5
65.5
23
CONCLUSION In this study, an analysis approach for condition monitoring and fault diagnosis in pantograph and catenary systems has been presented. The variation of contact points between the pantograph strip and contact wire for three speed values are given. The stable and faulty conditions are compared by examining with the developed diagnosis algorithm. The importance of the contact between pantograph and catenary in safe region is emphasized with obtained results. It is confirmed that the contact point is on the safe region in the stable condition and it passes to the fault region from the dangerous region in the fault condition. The contact can move to the dangerous region from the safe region for a short time due to the weather conditions, a temporary ground or rail disturbance or any reason. If this contact point’s variation in dangerous region is under the ratio of 5%, there is no problem and no need to take a precaution, it is a temporary condition and negligible. However, if the contact point’s variation is above the ratio of 5% and continues to increase, it is necessary to take precautions as soon as possible and preventing the passage of the contact to the fault region is required. Because, when a contact forms in fault region, it is almost impossible to avoid the problems. All of these show the importance of periodic condition monitoring for PAC systems. A problem can turn into a fault in the future so the pre-estimation and the resolution of it is important. In this way, the encountered faults in railway systems, pantograph and catenary damages and the cost of the system will be decreased. The amount of contacts in the end points of the pantograph and the wear of pantograph strip will be known. If a fault occurs, it will be identified and evaluations will be done. After determining the fault type, appropriate measures will be taken and the efficiency of the system will be increased. REFERENCES [1]
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