Applied Mechanics and Materials Vol. 577

Abstract: To consider the safety of a certain cross flow hydro-turbine generating units and the hydropower plant, the finite element model of the plant and units are established by ANSYS, with which the resonance check is carried out. Meantime, the spectrum analysis method is used to present an earthquake response analysis according to the relative specifications, and the earthquake reaction condition in different directions of the characteristic monitoring points in main height is obtained, then the vibration characteristics of the hydropower plant and the effect of the earthquake load are analyzed. The research gives evidence and reference to make sure of the plant structure safety and the healthy operation for hydro-turbine.

Abstract: This paper describes a low cost solar tracker with high efficiency in PV generating system. The detecting device adopts two ultraviolet (UV) sensors to detect the sun’s position. The output of detecting device is a series of combination signals. And this output signal is directly used to control DC motor’s deflection to sun. No microcontroller is adopted in this design. The simple structure makes this solar tracker reliable and easy implementation.

Abstract: Single of phasor measurement unit (PMU) in smart grid is analyzed. On the power transmission links, single of voltage and current are measured by kinds of PMUs, messages of PMUs are concentrated to PDC (Phasor data concentrator) and super PDC in power systems. Signal quality is important to power transmission, power utilization and power control for stability a power system. Harmonics, inter-harmonics, decaying DC (direct current) offset, and additive white Gaussian noise are analyzed. Odd-number harmonics and inter-harmonics affect the quality of power signals. Decaying DC offsert components influence current signal of power transmission line whose model is modeled by EMTP (Electromagnetic transient program) worldwide. Noise is generally a negligible factor on power transmission lines, since signal-to-noise (SNR) is always below 40 dB.

Abstract: Analysis on potential problems as well as solutions of DC/DC communication power supply. In addition, inductive research has been conducted regarding DC system’s configuration, wiring, power supply mode and nominal voltage selection of existing substations to provide valuable reference for the design of DC system of substations in future.

Abstract: This paper explores the application of. ithium iron phosphate battery in substation DC system. This paper analyzes the system configuration and the advantages and disadvantages of lithium iron phosphate battery, explores the feasibility and economy of the application of lithium iron phosphate battery in power grid, also summarizes the technical route of lithium iron phosphate battery and provides reference for design of new type of batteries adopted in substation DC system in future.

Abstract: Two waste heat recovery systems of barbershops were presented to increase its heat utilization efficiency. One was the waste heat recovery system with water-to-water heat exchanger (WHR-HE). The other is the waste heat recovery system with both water-to-water heat exchanger and heat pump (WHR-HE-HP). The two waste heat recovery systems were analyzed by both economics and thermodynamics principles. Compared to conventional heat utilization systems of barbershops, the WHR-HE decreases annual energy consumption by 54.2%, and the WHR-HE-HP decreases annual energy consumption by 87.5%. The gain investment recovery periods of WHR-HE and WHR-HE-HP are below half one year. Compared to the WHR-HE, the WHR-HE-HP is with larger energy-saving potential, lower running cost, larger first cost and larger gain investment recovery period. The critical value of energy-saving financial subsidy is 0.778 ¥/W for the WHR-HE-HP. The WHR-HE-HP is very suited to the large and medium-sized barbershops, especially in the cold climate zone.

Abstract: The paper proposes a multifunction charger for LiFePO₄ battery. The proposed multifunction charger contains charge circuit for LiFePO₄ battery and state of charge (SOC) estimation system. With a micro processor integrated, the proposed charger is capable of digital control to improve the system reliability. The fast charger uses pulse current charging circuit which integrates micro processor, voltage detecting interface, current detecting interface and control software. The user can adjust the duty cycle and frequency of charging pulse by controlling the pulse width modulation (PWM) signal. The proposed battery state of charge estimation system is based on the radial basis function (RBF) neural network approach. The architecture of RBF neural network used in this project contains an input layer, an output layer and a hidden layer. Input layer has 3 neurons which are impedance, voltage, current of battery and output layer has one neuron which is SOC. To verify the performances of the proposed multifunction fast charger, a prototype charger has been tested on practical LiFePO₄ battery. The field practical operations of the prototype charger were studied in accordance with the conditions for the different charging modes.

Abstract: Management of power supply reliability is not only the quality management of equipment and power supply system, but also the safety management of equipment’s operation and power supply system’s maintenance. In order to analysis the reliability of 10kV distribution grid, on the one hand, this paper analyzed the structure characteristics of 10kV distribution grid and four kinds of wiring patterns, which were the main parts of 10kV distribution grid. On the other hand, it pointed out the reasons, which affected the distribution grid’s reliability and discussed the ways to improve the 10kV distribution grid’s reliability.

Abstract: The performance of solar double effect LiBr/H₂O absorption chiller in which the area of collector array is 27m² and cooling capacity is 10kW was studied. The simulation is based on the meteorological data of monthly typical day which was summarized from a year round data of subtropical Guangzhou. The distribution of hourly total efficiency and solar fraction was obtained. The system mean performance for different months was analyzed as well. Besides, it is concluded that better performance is gotten as the inlet temperature of collector is 120°C.

Abstract: This document focuses on motors and frequency conversion equipments of stations of West-to-East Gas Pipeline, and introduces the present main cooling ways. Against water consumption, power consumption, and other economical index, analyze the selection process of cooling scheme in engineering design. Compare with the cost, workload of operation and maintenance of water cooling, air cooling and motor cooling. The result shows that water cooling is practicable in West-to-East Gas Pipeline and has validated in the established engineering. The method of scheme comparison proposed by this paper provides a reference for subsequent design.With the development of electronics technology, medium voltage high power frequency conversion speed regulation technology is increasingly mature. The technology that frequency conversion motor drives compressor unit has been gradually used in the long distance pipeline pressure field of oil and gas under the condition of reliable power supply, to replace the traditional gas turbine, and becomes the first choice of the pressurization equipment of the long distance pipeline, because of advantages of high technology, high efficiency, energy conservation and environment protection, economic benefits and so on^[1-3].Stations of West-to-East Gas Pipeline are usually electrical driven. When the compressors operate, motors and frequency converters will produce large amounts of heat, which affects running state and equipment life. So choosing the economic and technological cooling water scheme is important for stations and the whole network to operate safely and stably^[4-6].