Mechanical and Electrical Technology IV

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Authors: He Liu, Xiang Nan Lv
Abstract: A mixed power grid model of wind power and thermal power was built. The largest output power of wind power and thermal power was gotten by simulation in the condition of ensuring the safety and stability of the grid. Taking largest output power as the boundary condition in economical analysis of the grid, the load dispatch scheme for wind power and thermal power was developed to ensure the optimal economy of the grid.
1056
Authors: Mao Fa Gong, Guo Liang Li, Wen Hua Xia, Qing Xue Liu, Jing Jing Wang
Abstract: Aiming at the problem that harmonic pollution is becoming more and more serious in power system, a new method to detect harmonics and inter-harmonics based on Hilbert marginal spectrum is proposed in this paper. Firstly, the original signal is decomposed into several Intrinsic Mode Functions through Empirical Mode Decomposition. Then Hilbert marginal spectrum is obtained through Hilbert Huang Transform. It contains the information of signal’s harmonics frequency and those amplitudes. Finally, both harmonics and inter-harmonics are detected by this method. Fourier transform lacks the ability of time-frequency analysis. Wavelet transform is affected by the selection of wavelet base. This method overcomes these shortages and can detect the component of each harmonic quickly and accurately. Simulation result verifies that this method can meet the requirement of voltage and current distortion detection in power system.
1060
Authors: Hong Wei Wang, Jun Liu, Hai Qing Xiao, Chao Wang
Abstract: The impact tests are generally performed at room temperature in actual standards, but in fact, the power battery work in variety of different environment temperatures. Therefore, the impact tests of the power battery were researched at different environment temperatures (-30°C, 20°C, 40°C and 65°C). The results showed that the impact can induce the internal short circuit, at the same time, if battery system is kept running at high environment temperature, the exothermic effect will induce the heat accumulation inside the battery, leading to thermal runaway and even the battery burning and explosion. The other result is that the higher the environment temperature is, the worse the battery thermal stability is. Temperature rise rate and maximum temperature was a linear relationship of the samples that did not burn during impact tests. And the temperature rise rate and maximum temperature was the cubic polynomial relationship of the samples that burn during impact tests. That is to say, the battery is prone to induce thermal runaway when the temperature rise rate is high.
1064
Authors: Yan Cheng, Jin Xin Huang, Chun Hui Yu, Li Zhang
Abstract: With the development of wireless sensor networks, energy supplying problem become critical. However, energy scavenging technology provides an efficient solution method, and it is the principal element for wireless sensors to facilitate on-site self-powering. A magnetic energy converter which can convert magnetic field energy to power is proposed when there is sufficient magnetic energy in substations. By modeling this converter, the inductive factor was defined to present energy harvesting capability and optimization was realized in terms of framework material, structural parameters and turns of coils. The research results present theoretical basis for optimal design of the energy scavenging devices.
1068
Authors: Xiao Feng Liu, Xiu Lian Lu
Abstract: In the condition of environmental excitation and the modal parameters can be identified to only use response data. Based on the improved stochastic subspace identification method, can avoid the fitting error from asynchronous samples, which can integrate asynchronous multi-groups response samples into synchronous pulsing response data, Finally, the identification results of different system order number was utilized to construct stable map to acquire more accurate identification and avoid lost root or duplicate root than the conventional method.
1072
Authors: Ying Liu, Ming Yue Zhai, Li Peng Lu, Yong Xiao Liu
Abstract: Load forecasting based on fractal extrapolation is a very important method. However, traditional methods exists several disadvantages such as vertical scale factor difficult to calculate, low-precision, difficult to use. Therefore, a method is proposed combined with self-similarity theory and fractal extrapolation theory to solve the above problems. In this paper, the self-similarity of electrical load historical data is analyzed using multi-resolution wavelet firstly. Then use the Hurst parameter values to calculate vertical scaling factors based on the values of Hurst parameter and the other four parameters of Iterative Function Systems (IFS) affine transformation. At last the electrical load forecasting curve was generated by the iterations system. Considering the actual practical application, the algorithm was used to forecast electrical load based on fractal extrapolation. The computer simulation resulted that this algorithm has advantages of high-precision, less-sample demands, less-interpolation points and easy to use.
1077
Authors: Hui Bin Sui, Ying Sun, Wei Jen Lee, Meng Liu
Abstract: An AMI platform for DG energy management is proposed to provide service both utilities and customers in this paper. By enabling the interactive and efficient communication platform, the proposed AMI facilitates utilities to perform the energy management of DGs, economic dispatch and demand response effectively. Base on the CIM model, OSGi platform leads the AMI extendibility and Interoperability. The communication network includes several advanced communication technology which are used in distributed systems, if the AMI for DG can share the communication network and smart terminal even some advance application software in the utility information platform, it will work more powerfully and effectively.
1081
Authors: Kyoung Hoon Kim, Chul Ho Han
Abstract: Recently the power generation systems using ammonia-water binary mixture as a working fluid have been attracted much attention for efficient conversion of low-temperature waste heat sources to useful energy forms. In this work, ammonia-water based Rankine (AWR) and regenerative Rankine (AWRR) power generation cycles are comparatively analyzed by investigating the effects of turbine inlet pressure on the performances of heat exchangers in AWR and AWRR systems. Temperature distributions of fluid streams in the heat exchanging devices are closely examined at different levels of turbine inlet pressure under the conditions that the minimum temperature difference of hot and cold streams reaches the prescribed pinch point. Results show that the position of pinch point and temperature distributions are sensitively affected by varying turbine inlet pressure, which might be the most important design consideration in the power systems using a binary working fluid.
1085
Authors: Yusak Tanoto
Abstract: This paper presents energy saving assessment on induction motors which are particularly being utilized in the small and medium industry. A walk-through motor energy audit is carried out in a typical type of industry in Indonesia to collect some important data. Strategy for annual motor energy saving is assessed involving energy efficient motor, variable speed drive, and capacitor bank. In addition, analysis is carried out to find impact on energy efficiency indicator as well as CO2 emission due to energy saving. It is revealed that the combination on selected motor saving strategy may lead to reduce electricity energy by around 10%, equal to around 38% CO2 emission mitigation. Besides, energy efficiency indicators are found to be improved. Hence environment emission is significantly reduced by applying appropriate motor energy saving for small and medium industry.
1090
Authors: Gholamreza Sayyad, Amin Khodabakhshian, Rahmatollah Hooshmand
Abstract: This paper develops a power system stabilizer (PSS) design for a wind turbine equipped with doubly fed induction generator (DFIG) which is based on vector control to improve the performance and dynamic stability of DFIG under fault conditions. The proposed PSS design is combined with genetic algorithm to obtain the higher-fitness answer as a strong optimization technique to the design of PSS parameters. A study network containing a wind farm equipped with DFIG was employed and all simulations will be carried out using MATLAB. It is shown that the employment of a proposed PSS can substantially enhance the contribution of a DFIG-based wind farm to network damping and dynamic stability.
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