J.R. Jimenez-Octavio

Active control strategy on a catenary–pantograph validated model

Dynamic simulation methods have become essential in the design process and control of the catenary–pantograph system, overall since high-speed trains and interoperability criteria are getting very trendy. This paper presents an original hardware-in-the-loop (HIL) strategy aimed at integrating a multicriteria active control within the catenary–pantograph dynamic interaction. The relevance of HIL control systems applied in the frame of the pantograph is undoubtedly increasing due to the recent and more demanding requirements for high-speed railway systems. Since the loss of contact between the catenary and the pantograph leads to arcing and electrical wear, and too high contact forces cause mechanical wear of both the catenary wires and the strips of the pantograph, not only prescribed but also economic and performance criteria ratify such a relevance. Different configurations of the proportional-integral-derivative (PID) controller are proposed and applied to two different plant systems. Since this paper is mainly focused on the control strategy, both plant systems are simulation models though the methodology is suitable for a laboratory bench. The strategy of control involves a multicriteria optimisation of the contact force and the consumption of the energy supplied by the control force, a genetic algorithm has been applied for this purpose. Thus, the PID controller is fitted according to these conflicting objectives and tested within a nonlinear lumped model and a nonlinear finite element model, being the last one validated against the European Standard EN 50318. Finally, certain tests have been accomplished in order to analyse the robustness of the control strategy. Particularly, the relevance or the plant simulation, the running speed and the instrumentation time delay are studied in this paper.

CANDY statement of methods

This paper presents a detailed overview of CANDY, a catenary–pantograph dynamic interaction software. Authors describe the main key points of the formulation, focusing on its time-integration scheme, the pantograph and contact models as well as the solution of the initial equilibrium problem. Nonetheless one of the most important features of CANDY is its moving finite element mesh, which enables accurate results without excessive computational cost. The validation of the model against the European Standard EN 50318 and some conclusions and comments about the results of the benchmark are also included.

Influence of Track Irregularities in the Catenary-Pantograph Dynamic Interaction

This paper presents an advanced pantograph-catenary-vehicle-track model, which allows us to analyze the vertical dynamics of the complete system. The developed model is able to evaluate the displacements and the contact force generated in the catenary-pantograph as well as the wheel-track interactions. Nevertheless, this paper focuses on the possible influence of track irregularities on the catenarypantograph dynamic interaction. From a power spectral density function of the track irregularities, 180 track profiles and their respective catenary pantograph vehicle track simulations have been generated. The wide range of results allows us to obtain some conclusions about the influence of the track profile in the catenary pantograph behavior.

Efficient Multi-objective Optimization for Gas Turbine Discs

An original multi-objective optimization strategy for aeronautical gas turbine discs is presented in this chapter. A sensitivity analysis together with an optimal design of experiments (DoE) are accomplished prior applying a multi-objective genetic algorithm (MOGA) based on a Kriging surrogate model. Fatigue life prediction and total geometry mass are taken as optimization objectives in this work, whose results can be validated against laboratory tests but going further experimental conditions. To begin with, (i) a first case study considers laboratory test conditions, basically centrifugal loads due to the blades and the own mass of the disc. However, (ii) a second case study considers real conditions such as the centrifugal loads, airflow forces and thermal loads as well as taking into account different typical materials for this application. Results show that the proposed methodology successfully leads to the optimal geometric parameters both for laboratory and real conditions. The main conclusions and qualitative differences are finally summarized, highlighting the suitability of A718Plus among other materials and the Cob width parameter as the most critical one.

The Dependance on Mechanical Design in Railway Electrification: Focusing on the ac Perspective

Electrification of railway systems becomes a very tricky topic when designing overhead contact lines (OCLs). This article highlights the strong dependence of the mechanical design on the railway electrification. Indeed, only the high sensitivity of the quality of service to the mechanical performance of the OCL can explain the complex designs of the existing railway lines. The interoperability framework of the European Union together with the standards that tackle gauges and clearance calculations are briefly introduced, both for the static and dynamic analyses of the pantograph and catenary.

Coupled Electromechanical Optimization of Power Transmission Lines

This paper presents a multidisciplinary design and optimization method of power transmission lines. This optimization method solves both mechanical and electrical problems by a new strongly coupled method that also optimizes the potential designs using a genetic algorithm. A multi-objective function is formulated to simplify a constrained typical optimization problem into an unconstrained one. The scope of this work is the sizing and configuration optimization problem with fixed topology. The method is applied to a railway overhead transmission line. The genetic algorithm is applied to mechanical, electrical and electromechanical optimization problems obtaining good results. Finally, the solution of the electromechanical optimization problem is a trade-off between the multidisciplinary nature of the problem and the sort of optimization, sizing and configuration.

New Transformer Sizing Criteria Based on Moving Average Techniques for Railway Systems

This paper introduces new criteria based on moving average of apparent power for sizing transformers in railway systems. Usually, transformers are designed to fulfill thermal criteria which are evaluated along several load cycles reported in the standards and literature. Nevertheless, real railway load cycles are quite variable and difficult to predict, therefore simulation techniques are necessary to estimate them. Detailed thermal studies require electric and thermal simulations for very particular operation, maintenance and climatic conditions. Hence these studies are focused on that special conditions and imply high computational costs too. To face this problem new sizing design criteria are proposed. These are based on the calculation of the moving average of the demand power, considering a time window which depends on the thermal time constant of the transformer. Finally, the results obtained with the proposed design criteria are discussed and compared with those obtained with the conventional hot-spot temperature based criterion.Copyright

Coupled electromechanical cost optimization of high speed railway overheads

This paper presents a coupled electromechanical optimization of the cost of high speed railway overheads. The proposed electromechanical optimization solves the coupled mechanical and electrical problems by obtaining the railway overhead with minimum cost. A simple model cost of the railway overhead is proposed. This model cost defines the global cost per kilometer, which is mainly composed by the costs of material used in the construction of the overhead supports and the electric lines respectively. Using a standard genetic algorithm the optimized railway overhead is obtained. The parameters which describe the railway overhead are defined by: (i) sizing and (ii) configuration of the overhead supports; (iii) geometric location and (iv) type of electric conductors. The constraints considered are: (i) maximum allowable stress, and (ii) structural static stability; (iii) structure gauge to limit the position of physical conductors, (iv) minimum distance between conductors or between conductor and earth and (v) maximum allowable current of each conductor. In addition, the fitness function also considers the minimization of the equivalent electrical system impedance as a secondary optimization criterion. This optimization method has been successfully applied to the design of the high speed railway overhead C-350, used in the new line Madrid-Barcelona-French Border. The optimized railway overhead shows an overall improvement at two levels. Firstly, the performance is enhanced, and secondly, the global cost is reduced. The obtained results are compared with the non-optimized configuration in order to demonstrate the obtained improvements