Optimal energy saving in DC railway system with on-board energy storage system by using peak demand cutting strategy

Abstract A problem of peak power in DC-electrified railway systems is mainly caused by train power demand during acceleration. If this power is reduced, substation peak power will be significantly decreased. This paper presents a study on optimal energy saving in DC-electrified railway with on-board energy storage system (OBESS) by using peak demand cutting strategy under different trip time controls. The proposed strategy uses OBESS to store recovered braking energy and find an appropriated time to deliver the stored energy back to the power network in such a way that peak power of every substations is reduced. Bangkok Mass Transit System (BTS)-Silom Line in Thailand is used to test and verify the proposed strategy. The results show that substation peak power is reduced by 63.49% and net energy consumption is reduced by 15.56% using coasting and deceleration trip time control

Experimental Investigation on Affecting Air Flow against the Maximum Temperature Difference of a Lithium-Ion Battery with Heat Pipe Cooling

Research on battery thermal management systems (BTMSs) is particularly significant since the electric vehicle sector is growing in importance and because the batteries that power them have high operating temperature requirements. Among them, heat pipe (HP)-based battery thermal management systems have very high heat transfer performance but fall short in maintaining uniform temperature distribution. This study presented forced air cooling by an axial fan as a method of improving the cooling performance of flat heat pipes coupled with aluminum fins (FHPAFs) and investigated the impact of air velocity on the battery pack’s maximum temperature differential (ΔTmax). All experiments were conducted on lithium nickel manganese cobalt oxide (NMC) pouch battery cells with a 20 Ah capacity in seven series connections at room temperature, under forced and natural convection, at various air velocity values (12.7 m/s, 9.5 m/s, and 6.3 m/s), and with 1C, 2C, 3C, and 4C discharge rates. The results indicated that at the same air velocity, increasing the discharge rate increases the ΔTmax significantly. Forced convection has a higher ΔTmax than natural convection. The ΔTmax was reduced when the air velocity was increased during forced convection

Evaluation of rail potential and stray current reduction by using NEG-ETP in DC railway system

The NEG-ETP system that providing zero resistance closed circuit reducing the reverse path of current on the running rail is presented in this article. The NEG-ETP system is created by installing additional electronics in conventional electrical systems. Without modifying trains, tracks, or tunnels. Using MATLAB program through models for MRT purple line (North), rail potential and stray current are assessed in accordance with EN 50122 standards of all three systems, including CON-ETP, REC-ETP, and NEG-ETP. According to the simulation, the percentage reduction of the rail potential was 9.14% when the REC-ETP versus the CON-ETP system was 32.99% when the NEG-ETP system compared to the CON-ETP system and 26.25% when the NEG-ETP system versus the REC-ETP system could be seen in this negative resistance converter system, which can reduce the cost of rails and leakage currents in the DC system. It can also be applied to new rail transport

Fine Tuning of On-Board Traction Converters for High-Speed Electric Multiple Units at Depot

This article presents a meticulous exploration of on-board traction converters deployed in Electric Multiple Units (EMUs). The study involves the development of a comprehensive traction converter and control system, encompassing essential elements such as transformers, front-end rectifiers, and DC link capacitors. The precise control of the front-end rectifier’s switching states is crucial for achieving high-quality power. A new application of the advanced Hybrid Particle Swarm Optimization (Hybrid PSOS) technique for the optimization of controller parameters is presented. This parameter tuning process aims to minimize the integral time absolute error (ITAE), a critical metric governing the regulation of DC-link capacitor voltage. Simulation results showcase the impressive attributes of on-board traction converters, including low harmonic content, a high-power factor, and stable DC voltage. Additionally, a rigorous comparative analysis is conducted between Hybrid PSOS and other established algorithms like Symbiotic Organisms Search (SOS) and Particle Swarm Optimization (PSO). Hybrid PSOS traction unit outperforms SOS and PSO, with a minimal overshoot of 1.3401%, faster settling time of 0.2413 seconds, compared to SOS (0.3884 seconds) and PSO (0.5531 seconds). Total Harmonic Distortion (THD) for secondary line currents, the values are 12.48% for PSO, 2.17% for SOS, and 1.08% for Hybrid PSOS. Hybrid PSOS consistently demonstrates its superiority, significantly enhancing system performance and stability. This research underscores the substantial potential of on-board traction converters, emphasizing their role in facilitating efficient and stable electric multiple unit (EMU) operations