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In this paper, the IGBT open-circuit fault characteristics in sub-module(SM) for Modular multilevel converter(MMC) are studied, and a fault detection method based on mean value of the three-phase ac current to extract fault characteristics and support vector machine(SVM) classification is proposed. When a fault occurs, the mean value of three-phase ac current is no longer zero, which can detect the occurrence of the fault. When the open-circuit fault occurs in the SMs of different bridge arms, the mean value of three-phase ac current produces different dc bias components. According to the change rule of the mean value of three-phase current, the fault characteristics are extracted, and then faults are classified with SVM classifier. Finally, experimental results show that the proposed method can detect the fault quickly and classify the faults accurately.

With the rapid development of the urban transit rail, overload operation has become one of the main reasons for the failure of urban transit rail vehicle structure. Herein, we conducted a tracking experiment on the urban transit rail vehicle in-service and investigated the fatigue life of the bogie frame. Load experiment of urban transit rail vehicle was carried out to measure the maximum vertical load and obtain the load histories under overload situation. Furthermore, based on JIS E4207 standard, the stress of ten main in-service cases is calculated using finite element method. According to the actual operation results, five critical stress locations are chosen to assess the fatigue strength of bogie frame. A new fatigue limit diagram combined with Morrow relation is applied to analyze fatigue strength of these locations and is utilized to identify if the positions are dangerous. The investigation result shows the welding location around air spring seat cannot satisfied the necessary of fatigue lifetime.

Traction inverter is one of the most important part of traction drive system in the train, and the reliability of the traction inverter affects the normal operation of the entire train directly. In this paper operated the accelerated test on IGBT module of TNG15 type traction inverters in the Beijing metro firstly. Then calculated the failure rate of IGBT module through Arrhenius model, for the coupling element, used small-sample method of reliability evaluation to calculate the failure rate of it. Combined with the reliability parameters of other electronic components in the traction inverters, the qualitative analysis and did the quantitative analysis of traction inverter system through GO methodology. GO method is widely used in the defense industry and other large systems, but it is rarely involved in the small systems. This paper provides a method for the reliability assessment of traction inverter, and it provides an idea for the reliability assessment of the other converter components in the train traction transmission system.

In this paper, the open-circuit fault of the submodule (SM) in modular multilevel converter (MMC) are analyzed. Aiming at the open-circuit fault characteristics of the submodule, a fault detection method based on the average value of the three-phase AC current is proposed. The average value of three-phase AC current is utilized to detect the occurrence of the submodule fault, the size of the AC average current is used to locate where the phase arm the fault submodule is on, the sign of the AC average current is employed to locate which arm of the faulty submodule is on. And then, the submodule fault switch can be determined by using the maximum size for the sum of three-phase AC average current.

In the past years, most task scheduling algorithms consider either to minimize the application's completion time or to minimize the application's energy consumption subject to a deadline constraint. Few of them can achieve these two performance goals at the same time. In this paper, we propose an energyaware importance-ratio-based stochastic task scheduling (EISTS) algorithm, which makes a good balance between the makespan and energy consumption and achieves high system weighted improvement based on the importance-ratio of makespan toenergy consumption for heterogeneous parallel systems. Compared with other existing algorithms, our algorithm can achieve shorter application's completion time when the importance-ratio of makespan to energy consumption is high. On the contrary, our algorithm consumes less energy. To prove its validity, we compare our proposed algorithms with two existing scheduling algorithms(SHEFT and ECS) in terms of system weighted improvement, makespan, and energy consumption respectively. The results of simulations show that the system weighted improvement of our algorithm and those two compared algorithms are 37%, 17%, and 18% respectively, which clearly demonstrates that ourEISTS algorithm outperforms them significantly. In addition, our algorithm is also very competitive in terms of both makespan and energy consumption.

This paper presents a multi-scale dynamic optimizing method to improve the load characteristics of the regional power system based on the particle swarm optimization (PSO) algorithm. The optimizing strategy is operated as minimizing the peak-valley gap, load variance, and load fluctuation to be objective functions, respectively, and the scale of charging station and the demands of customers to be constraints. The customers' travel performance is simulated by the stochastic method of probability distribution. And EV loads of coordinated and uncoordinated charging are integrated into a typical regional power system. Further, the results of the three objectives are contrasted. The conclusion shows that the dynamic coordinated charging strategy, especially the one for load gap, takes the most positive effect in characteristics of regional power system load in this dynamic process.