Applied Mechanics and Materials Vols. 672-674

Abstract: The assessment of the winding deformation of transformer has a certain practical significance. In this paper, an Improved Ultrasonic Ranging (IUR) method is proposed to assess the winding deformation of transformer. Firstly, the basic principle of winding deformation detection using ultrasonic and the working principle of detection device are discussed. Secondly, the impact of the factors such as transformer oil temperature and echo signal attenuation on the test results is analyzed. Then, a new IUR method is composed, which can realize the on-line monitoring of transformer winding deformation. Finally, an assessment equipment of transformer winding deformation based on the online monitoring is developed, and a prototype is used to test the transformer mode, proving that this method is feasible.

Abstract: This paper forecast the electric load of the mass electric cars connected to the electric grid in charging and discharging; considered the inventory forecast of electric vehicles; comprehensive analyzed the charge and discharge characteristics of the electric cars’ charging infrastructures and the impact factors such as users’ behaviors as well as the using frequency, which lead to different load distribution at different times. It calculated the total load of electric vehicles into the load curve and the load curve of the characteristics under different regions (industrial, commercial and residential). Concludes that the mass electric cars connected to the electricity grid will increase the peak load of power grid, and lay the foundation for the subsequent market management and optimization control.

Abstract: Energy harvesting shock absorber is used for harvesting the kinetic energy in the vehicle suspension vibration. In this paper, we present design, modeling, and simulation of a novel energy harvesting shock absorber based on rack and pinion mechanism. The shock absorber consists of three main components: the mechanical vibration input, the transmission module, and the micro-generator module. The shock absorber is installed between the vehicle frame and chassis to obtain a relative linear motion acting as mechanical vibration input. The function of transmission mechanism module is to convert the relative linear motion to a unidirectional rotation for the input shaft of micro-generator. The micro-generator will produce electricity due to the input shaft rotating in one direction. This shock absorber was tested in simulation condition, and the last performance evaluation demonstrates the validity of the proposed energy harvesting shock absorber.

Abstract: The increasingly serious energy crisis and environmental pollution problems promote the large-scale application of microgrids (MGs) and electric vehicles (EVs). As the main carrier of MGs and EVs, distribution network is gradually presenting multi-source and active characteristics. A fast service restoration method of multi-source active distribution network with MGs and EVs is proposed in this paper for service restoration of distribution network, which takes effectiveness, rapidity, economy and reliability into consideration. Then, different optimal power flow (OPF) models for the service restoration strategy are constructed separately to minimize the network loss after service restoration. In addition, a genetic algorithm was introduced to solve the OPF model. The analysis of the service restoration strategy is carried out on an IEEE distribution system with three-feeder and eighteen nodes containing MGs and EVs, and the feasibility and effectiveness are verified

Abstract: Plug-in hybrid vehicles (PHEVs) combine the motor and traditional internal combustion engine with their full advantages, they have great advantages in practical application, are an important direction to develop the energy saving and emission reduction vehicles. The PHEVs’ capacity of battery pack determines the continuous mileages under the pure electric mode, the larger the capacity of battery pack is, the higher the PHEVs’ cost is. But the continuous mileages under the pure electric mode are longer, the fuel cost of consumers is lower. For ordinary consumers, economy and utility are two important factors to purchase PHEVs. Considering different consumers, city forms and people use habits, the PHEVs’ optimum continuous mileages under the pure electric mode for suitable promotion were presented, to make they have the optimum consumer ownership cost, have the important practical significance to promote the development of PHEVs in different area.

Abstract: Aiming at the problem of electric vehicle charging station planning, the clients of fast charging stations is analyzed. The optimal mathematical model about siting of electric vehicle charging stations is proposed based on the city's geographic information. We obtain the optimal location of charging stations by charging convenient factor as a constraint. And divide the load area which is served by each charging station by the Voronoi. According to the load which is served by each charging station, this paper designs the optimal battery charger number of each charging station with the Queuing Theory. Finally, optimize the charging convenient factor using the total cost as objective function. The analysis of examples verifies the effectiveness and the practicability of the proposed planning approach.

Abstract: A novel position sensorless control strategy integrated with full section and high precision for a permanent magnet synchronous motor (PMSM) applied to wind power pitch was proposed in the paper. Based on high frequency signal, where three-phase triangular carrier spwm is injected and the state current response is detected to accurately estimate the rotor position in the still and low speed, which doesn’t rely on the non-ideal features. Based on BEF PMSM mathematic model, the phase locked loop technique is used to accurately detect the rotor position in the middle and high speed. the Finally, experiment on a 10 KW pith system demonstrates that the proposed method is effective and is capable of achieving more accurate control in the full speed section.

Abstract: Synchronous generator excitation failure can lead to loss of field, after field loss will lead to the generator lose synchronization. The slip is occurred on the rotor, the generator will absorb a large number of reactive powers from power grid. System voltage is reduced, may make some adjacent point voltage is lower than the allowable values, break the stable operation status between load and power supply, and even make the system voltage collapse; The increased stator current may cause other generator, transformer and circuit overload, make backup protection action, and increase the fault extent; From the perspective of the experimental, this article analyzes the change of stator current in the process of QFQS – 200 synchronous generator loss of field, which provides data for the practical operation of the generator.

Abstract: Based on the study on basic principle of rare earth permanent magnet brushless DC motor, the motor drive and protective circuit was designed in this paper. According to the work environment of brushless DC motor (BLDCM), the insulated gate bipolar transistor (IGBT) was chosen as a motor inverter unit core element, and IGBT special integrated drive chip VLA517-01R was used as the core to build IGBT driver protection circuit. High speed optical coupling isolation was used between drive circuit and control circuit, avoiding interference from drive circuit to the control circuit, ensuring the reliable operation of the system. Through the test it is proved that the designed circuit possesses good response, high stability, and when circuit fault happens it can reliably shut off IGBT output, feeding back fault signal.

Abstract: The paper focuses on the locomotive intelligent watt hour meter based on STM32. By designing Intelligent watt hour meter main function, hardware architecture, and software processes to achieve energy data display, storage, and duplex communication. The hardware structure consists of main control module, electric energy metering module, communication module and other components, electric energy metering module is responsible for data acquisition, the main control module is responsible for data processing, communications module is responsible for two-way communication. Using MATLAB software to simulate the newly developed Intelligent watt hour meter,the simulation results show that, the intelligent watt hour meter has the advantages of high precision, low power consumption, fast performance, strong anti-interference ability, low manufacturing cost etc.