Applied Mechanics and Materials Vols. 448-453

Abstract: Algorithm and realization of the arrester in cable line in online-monitoring system based on the resistive current detection using phase search is discussed in this paper. The effectiveness of this method is manifested by the actual experience in the engineering construction.

Abstract: The research and development on the on-line monitoring system of cable line arrester is discussed from system composition, main functions of system, main features of the system and system development tools, and the practical experience of the construction indicates the necessity and effectiveness of the method.

Abstract: Wind speeds of different wind turbines in a big wind farm always have correlations because of their close geographical location. This paper builds wind speed model by t-copula function and uses rank correlation matrix to measure the correlation of wind speeds. The case study of IEEE-39 bus system and Yunnan Power Grid shows that wind speed correlation has certain effect on the transient stability of power system.Taking wind speed correlation into consideration makes the analysis of systems transient stability more close to reality.

Abstract: The stable operation of the secondary equipment is very important to the stable operation of power system. In order to improve the operation reliability of the secondary equipment and reduce personnel maintenance workload, the condition-based maintenance of secondary equipment is urgently needed. According to the field data, this paper established a set of evaluation index system, the system can accurately evaluate the secondary equipment status.

Abstract: With the fast development of clean energy in China, the conflict between limited peak load regulation capability and the increasing installed wind power capacity became more and more obvious. Two different wind power integration dispatching modes were proposed in this paper, meanwhile, the wind power integration capacity and system economy under different scenarios, which have different wind power penetration and energy storage system (ESS) capacity, were also analyzed. As indicated in the example analysis, the ESS can significantly enhance the wind power integration capacity; and the economical wind power integration dispatching mode is the most suitable choice for the power grid in wind-rich area.

Abstract: In order to improve the economy of operation of transformer, this study presents a strategy to ensure the safety of power transformer for the situation of overload operation of parallel transformer. According to the variation of actual transformer operation, the authors divide the daily load curve into two typical time periods. In the high load operation period, except the constraint of minimum power loss for the economic operation, the factor for hot-spot temperature rise of the transformer should also be considered, so that an economic operation mode and parallel switching time could be obtained. This strategy estimates the hot spot temperature by the finite difference method, and obtains the optimal switching time through binary searching, according to the environment temperature and load curve. The analysis of the example of the operation of two sets of three winding transformers in parallel with different capacity shows that the method of optimization of the operation could reduce the loss. In the meantime, it could ensure the operation safety of the transformer, and prolong the service life of transformer.

Abstract: As the aviation has realized the seriousness of pollution and emission issues, people have taken efforts to use renewable energy on planes or UAVs. This paper focused on the applications of solar and hydrogen energy to UAVs. A hybrid power system, consisting of solar cells, fuel cells and lithium batteries, was discussed. To achieve the hybridization of power sources, a prototype of a power management unit (PMU) was fabricated. After the installation of a test system for synthesizing power sources, PMU and load, a series of ground tests were executed to verify the mathematical model of lithium battery and the reliability of the hardware. Ground data confirmed the feasibility of hybrid power system.

Abstract: To solve problems like slow computing speed and system operation speed, low system stability and reliability, which were encountered at implementing traditional region-county integration dispatching automation system (DAS) in a large scale region-county dispatching system, this paper provides a new type construction mode of region-county integration system, i.e. distributed and autonomous disaster tolerance backup system. It redesigns the structure of region-county integration system from aspects of network structure, model integration, data integration, application integration, separated operation and remote backup, provides wide area remote interconnection of region DAS with county DAS distributed at each county to make them become one logical set of system and realize share of data, technologies and equipment sources, save cost of system maintenance and construction, improve the reliability of DAS, realize remote disaster tolerance and backup and improve region-county operators' professional ability and technological level.

Abstract: There is a restriction on the development of power quality monitoring software for lacking of corresponding technical specification and uniform systematic planning. In this thesis, the concept of supporting platform of power quality monitoring and analysis system is posed and the supporting platform provides data service, report work, authority management, alarm service, authority management, communication service and other public services; abiding by the advocacy of IEC 61970 Standard, the system applies CORBA component technology inside and outside the system and realizes the “plug and play” of public services and applications. Through the standardized public communication service module, the data interaction with other power quality monitoring software, PMS system, DMS/EMS system and other third-party systems is completed and the multi-angle and deep power quality analysis are conducted based on multi-source information fusion technology and the power quality analysis and evaluation, harmonic source location, power quality warning, management decision support and other intelligent analysis application are realized.

Abstract: Causes of electrical fires have great variety. In view of the main, this paper explores the algorithm of fault arc detection and the method of electric appliance identification, and briefly shows the overall design of the monitoring system. The judging threshold of fault arc can be carried out through building an AR model of normal current signal and calculating the coefficients of the AR model with the third-order Burg algorithm. The existence of fault arc can be determined by the squared Euclid distance between the threshold and the coefficients of current signal. The pattern recognize based on the Fourier series of current signal as characteristic values can be used as Electrical appliances identification methods combined with the power of appliance.