scholarly journals A partial compensation scheme for MMC-based railway cophase power supply

2020 ◽  
Vol 2 (4) ◽  
pp. 305-317
Author(s):  
Peiliang Sun ◽  
Kang Li ◽  
Chen Xing
Keyword(s):  
Power Factor ◽  
Power Supply ◽  
High Speed ◽  
Current Phase ◽  
Compensation Scheme ◽  
Railway Systems ◽  
Grid Side ◽  
Phase Angles ◽  
Traction Load ◽  
Partial Compensation

Abstract This paper presents a partial compensation scheme for V/v transformer cophase traction power supply in high-speed railway systems. The scheme compensates variable traction load current, and controls the current phase at the secondary side of the V/v transformer for power factor correction and negative sequence current reduction. To achieve this, the grid side current phase angles are optimized while satisfying the grid code on the power factor and voltage unbalance limits. The optimized phase angles are then used to design control references under varying load conditions. The compensation control action is updated regularly based on real-time measurements of the traction load, and the required currents are controlled by a 25-level single-phase back-to-back MMC power conditioner to achieve the compensation target. Static and dynamic load compensation performances are verified based on the simulation studies.

Research on Energy-Saving EDM Pulse Power Supply

2008 ◽  
Vol 375-376 ◽  
pp. 714-718
Author(s):  
Yu Kui Wang ◽  
Bo Yan Song ◽  
Zhen Long Wang ◽  
Wan Sheng Zhao
Keyword(s):  
Energy Saving ◽  
Power Factor ◽  
Power Supply ◽  
High Speed ◽  
Closed Loop ◽  
Pulse Generator ◽  
Electrical Discharge Machining ◽  
Pulse Power ◽  
Electrode Wear ◽  
Pulse Power Supply

The performance and stability of output of electrical discharge machining (EDM) are determined by the output of EDM pulse power supply. In order to resolve disadvantages of conventional pulse power supply, such as undesirable efficiency and low power factor, the prototype design of energy-saving EDM pulse power supply is developed. It is composed of such three stages as a single-phase active power factor correction (PFC) pre-regulator, a full-bridge phase shift zero voltage switching (FB-PS-ZVS) converter based on complex control paralleled of machining current closed-loop and voltage closed-loop at period of spark gap insulation, and a pulse generator based on machining sequence control. The PFC pre-regulator contributes to a great increase to about 0.95 in its power factor. The efficiency of the new system is considerably increased to about 70% due to design of ZVS. The pulse generator contributes to the pulse machining current without a tail. Experiment results demonstrates that the prototype is capable of low electrode wear, high speed, stable machining.

scholarly journals Assessment of the Worthwhileness of Efficient Driving in Railway Systems with High-Receptivity Power Supplies

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1836 ◽  
Author(s):  
Alejandro Cunillera ◽  
Adrián Fernández-Rodríguez ◽  
Asunción P. Cucala ◽  
Antonio Fernández-Cardador ◽  
Maria Carmen Falvo
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Energy Savings ◽  
Real Data ◽  
Energy Usage ◽  
Running Time ◽  
Railway Systems ◽  
Ac Power ◽  
Driving Speed ◽  
Regenerative Energy

Eco-driving is one of the most important strategies for significantly reducing the energy consumption of railways with low investments. It consists of designing a way of driving a train to fulfil a target running time, consuming the minimum amount of energy. Most eco-driving energy savings come from the substitution of some braking periods with coasting periods. Nowadays, modern trains can use regenerative braking to recover the kinetic energy during deceleration phases. Therefore, if the receptivity of the railway system to regenerate energy is high, a question arises: is it worth designing eco-driving speed profiles? This paper assesses the energy benefits that eco-driving can provide in different scenarios to answer this question. Eco-driving is obtained by means of a multi-objective particle swarm optimization algorithm, combined with a detailed train simulator, to obtain realistic results. Eco-driving speed profiles are compared with a standard driving that performs the same running time. Real data from Spanish high-speed lines have been used to analyze the results in two case studies. Stretches fed by 1 × 25 kV and 2 × 25 kV AC power supply systems have been considered, as they present high receptivity to regenerate energy. Furthermore, the variations of the two most important factors that affect the regenerative energy usage have been studied: train motors efficiency ratio and catenary resistance. Results indicate that the greater the catenary resistance, the more advantageous eco-driving is. Similarly, the lower the motor efficiency, the greater the energy savings provided by efficient driving. Despite the differences observed in energy savings, the main conclusion is that eco-driving always provides significant energy savings, even in the case of the most receptive power supply network. Therefore, this paper has demonstrated that efforts in improving regenerated energy usage must not neglect the role of eco-driving in railway efficiency.

Research on Highly Efficient EDM Pulse Power Supply and Its Experiments

2005 ◽  
Vol 291-292 ◽  
pp. 567-572 ◽  
Author(s):  
Yu Kui Wang ◽  
Bo Yan Song ◽  
Wan Sheng Zhao
Keyword(s):  
Power Factor ◽  
Power Supply ◽  
High Speed ◽  
Closed Loop ◽  
Pulse Generator ◽  
Electrical Discharge Machining ◽  
Pulse Power ◽  
Electrode Wear ◽  
Pulse Power Supply ◽  
Highly Efficient

Their efficiency and their power factor of conventional independent electrical discharge machining (EDM) pulse power supplies with the current-limiting-resistor circuit is so low that they do not meet the need of advanced EDM technologies. The design of highly efficient EDM pulse power supply based on switching circuit pulse width modulation current closed-loop principle has been initiated. It is composed of such three stages as a single-phase active power factor correction preregulator, a full-bridge phase shift resonant converter based on machining current closed-loop control and a pulse generator based on machining sequence control. Therefore, the efficiency of the new system is considerably increased to about 70%, its weight and size is decreased much. Its power factor is a great deal increased to about 0.95. Experiment results have demonstrated that the highly efficient EDM pulse power supply is capable of low electrode wear, high speed, stable machining.

Design of New Load Balancers for Modern High Speed Railway Systems

2010 ◽  
Vol 11 (1) ◽  
Author(s):  
Wen-Shyan Chu ◽  
Jhy-Cherng Gu ◽  
Sanyi Lee ◽  
Bin-Kwie Chen
Keyword(s):  
Low Power ◽  
Imaginary Part ◽  
Power Factor ◽  
High Speed ◽  
Positive Sequence ◽  
High Speed Railway ◽  
Railway Systems ◽  
Delta Type ◽  
Load Balancer ◽  
Negative Sequence Current

Traditional electric trains have a low power factor, high loading variation change and inefficiency, generating both negative sequence current and the imaginary part of positive sequence current. Delta type Load Balancer associated with specially connected transformers is generally adopted to correct power factor and voltage imbalance. However, the modern trains used in High Speed Railway (HSR) have a power factor approximately close to unity, and therefore only need voltage imbalance correction. This study presents novel Load Balancer schemes, which are a modification of the Delta-type Load Balancer, with various connected transformers to correct imbalance. The symmetric component method is also adopted to determine the installation capacity of the proposed Load Balancer schemes.

New Criteria for Estimating Voltage Unbalance Due to Special Connected Transformers in High Speed Railway Systems

2005 ◽  
Vol 4 (1) ◽  
Author(s):  
Wen-Shyan Chu ◽  
Jyh-Cherng Gu ◽  
Bin-Kwie Chen ◽  
San-Yi Lee
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Power Supply System ◽  
Supply System ◽  
Two Dimensional ◽  
High Speed Railway ◽  
New Approach ◽  
Voltage Unbalance ◽  
Railway Systems ◽  
New Criteria

Specially connected transformers can reduce the voltage unbalance in a High Speed Railway (HSR) power supply system. Differently connected transformers reduce unbalance differently. Traditionally, a two-dimensional figure is used to represent the degree of unbalance associated with specially connected transformers. However, such a figure cannot completely express the conditions under which the voltage unbalance factor (VUF) is maximized. This work proposes a new approach to creating figures that represent the VUF of specially connected transformers under different dispatch schedules. Besides helping engineers to estimate voltage unbalance associated with various connected transformers, the analytical results can also provide a valuable reference for train dispatchers of HSR to plan dispatching.

Case study: Prediction and field tests of railway noise and effects of a low-height noise barrier

2020 ◽  
Vol 68 (4) ◽  
pp. 303-314
Author(s):  
Yuna Park ◽  
Hyo-In Koh ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
University of Science and Technology, Transpo ◽  
...  
Keyword(s):  
High Speed ◽  
Field Tests ◽  
Residential Areas ◽  
Railway Systems ◽  
Railway Noise ◽  
Sound Levels ◽  
Noise Barrier ◽  
The Difference ◽  
Reduction Effect ◽  
The Impact

Railway noise is calculated to predict the impact of new or reconstructed railway tracks on nearby residential areas. The results are used to prepare adequate counter- measures, and the calculation results are directly related to the cost of the action plans. The calculated values were used to produce noise maps for each area of inter- est. The Schall 03 2012 is one of the most frequently used methods for the production of noise maps. The latest version was released in 2012 and uses various input para- meters associated with the latest rail vehicles and track systems in Germany. This version has not been sufficiently used in South Korea, and there is a lack of standard guidelines and a precise manual for Korean railway systems. Thus, it is not clear what input parameters will match specific local cases. This study investigates the modeling procedure for Korean railway systems and the differences between calcu- lated railway sound levels and measured values obtained using the Schall 03 2012 model. Depending on the location of sound receivers, the difference between the cal- culated and measured values was within approximately 4 dB for various train types. In the case of high-speed trains, the value was approximately 7 dB. A noise-reducing measure was also modeled. The noise reduction effect of a low-height noise barrier system was predicted and evaluated for operating railway sites within the frame- work of a national research project in Korea. The comparison of calculated and measured values showed differences within 2.5 dB.

Ensuring electrical safety of power supply systems of electrified AC railways for highspeed lines

2018 ◽  
Vol 77 (6) ◽  
pp. 337-346 ◽  
Author(s):  
A. B. Kosarev ◽  
A. V. Barch ◽  
E. N. Rozenberg
Keyword(s):  
Power Supply ◽  
High Speed ◽  
Structural Features ◽  
Electrical Safety ◽  
Safe Operation ◽  
Ballastless Track ◽  
Conventional Structure ◽  
Artificial Earth ◽  
Earth Connection ◽  
Supply Systems

Abstract. High-speed railways are fast-growing and promising type of traffic. In Russia development of high-speed railway service is associated with the solution of a number of problems, including infrastructure. Authors propose to use earth connection of the railway catenary with the help of an artificial earthing switch on currently designed high-speed line Moscow—Kazan for 2×25 kV power supply system. Taking into account requirements for electrical safety conditions for maintenance of the track and earthed catenary supports, paper justifies method for calculating allowable voltages of rail—earth points and supports of catenary. Methods takes into account structural features of ballastless track superstructure used for high-speed lines. It is estimated that the voltages admissible under the electrical safety conditions are random in nature and distributed logarithmically normal. When calculating probability of safe operation, one should take into account random nature of both permissible stresses and those actually occurring on the track. It is estimated that the probability of safe operation in traction networks of sections with ballastless track superstructure does not exceed a similar value in electrified sections with the conventional structure of a ballast prism. Feasibility of using a 2×25 kV earth system using an artificial earth connection is confirmed, recommendations on its use are given. Authors substantiate allowable values of the rail—earth voltage and catenary supports, which practically exclude the occurrence of hazardous situations for personnel maintaining the track in sections with ballastless track superstructure.

Sign in / Sign up

Export Citation Format

Share Document