by Ching-Sung Wang and S. M. Chen
Case Presentations
The population structure of Taiwan is evolving toward aged society. The ratio of elderly population over total population is increasingly approaching to 1/4 or above, leading to the increasing demand of the aged care in Taiwanese society. Further the increasing the long-term care cost would have a great impact on National financial burden. As for the delimitation on the growth rate of the elder population, we would like to develop an auxiliary aid capable of reminding people’s daily exercise, as well as detecting the people’s aged degree. In this study we implement such an aid by a cost-effective, intelligent ring type sensor capable of measuring people’s essential tremor as well as recording people’s daily exercise/showing them up at a user friendly interface. Based on the state of the art sensor technology, the intelligent sensor comes out to be capable of recording aged people’s essential tremor spectrum via fast Fourier transform (FFT) and their daily exercise simultaneously. With gathering both of detecting information, the sensor would be transmitting the information in a real-time fashion toward people’s cellular phone via a Bluetooth interface. Then an application on the phone could evaluate the degree of the aging and show the daily sport records toward the medical staff at the remote site. In order encourage elderly people to exercise and prevent elderly people from falling accidentally, the device also has fall warning function. It is believed via such a surveillance on elder people and referring their daily sport records in a long term fashion, the phenomenon of population aging could be effectively improved.
American Journal of Electrical and Electronic Engineering. 2020, 8(3), 98-101. DOI: 10.12691/ajeee-8-3-5
Pub. Date: August 13, 2020
4727 Views612 Downloads
by Rahmon Kamorudeen Adewale, Ogunti Erastus Olarewaju and Apena Waliu Olalekan
Communication
The demand for high data rate transmission is rapidly increasing in the area of wireless communications and Orthogonal Frequency Division Multiplexing (OFDM) is known to be a promising technique for high-rate transmission that can overcome the inter symbol interference (ISI) which results from the time dispersive nature of wireless channels. The idea is to utilize a number of carriers, spread regularly over a frequency band, in such a way so that the available bandwidth is utilized to maximal efficiency. This study presents the comparison of the performance of different modulation schemes: M-ary phase shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) over Additive White Gaussian Noise (AWGN), Rayleigh and Rician multipath fading channels in OFDM system. Bit error rate (BER) was used to evaluate the performance of the system; the number of fast Fourier transform (FFT) points used during the transmission was also examined. The results showed that for all the channels, lower order modulation schemes perform better than the higher order schemes. This comes at the detriment of the data rate, as lower order schemes have lower data rates compared with their higher order counterparts. In addition, it was observed that the system performed better in AWGN channel than Rayleigh and Rician fading channels for all the modulation schemes used. It was observed that the number of FFT points used during the transmission do not have much effects on the performance of the system.
American Journal of Electrical and Electronic Engineering. 2020, 8(3), 91-97. DOI: 10.12691/ajeee-8-3-4
Pub. Date: August 13, 2020
4221 Views352 Downloads
by Xiaotian Xu, Xiao Lv, Xinyuan Zhang and Xiaotian Xu
Original Research
The remaining capacity of the photovoltaic inverter has achieved good results in solving the problem of the voltage limit of the grid-connected point of the distributed photovoltaic power generation system. But at present, in order to increase the reactive power capacity of the inverter, related research mainly focuses on limiting the power output of the inverter, without considering the impact on the penetration rate of the distributed photovoltaic power generation system. This paper clarifies the mechanism of the voltage limit of the grid-connected point of the distributed photovoltaic power generation system, and proposes a coordinated control strategy for the voltage of the distributed photovoltaic grid-connected point that takes into account the local load. Use back-to-back converters to control the local load reactive power of photovoltaic power generation, and change the output power of photovoltaic power generation by controlling the working status of the grid-connected inverter. Set up the brake control link. When the limit is exceeded, the local load reactive power control will be given priority to adjust the grid-connected point voltage, thereby avoiding the impact on the photovoltaic power generation capacity of the distribution network. Finally, experiments based on Matlab/Simulink simulation platform verify the feasibility and effectiveness of the proposed control strategy.
American Journal of Electrical and Electronic Engineering. 2020, 8(3), 84-90. DOI: 10.12691/ajeee-8-3-3
Pub. Date: July 29, 2020
5843 Views587 Downloads
by Xinyuan Zhang, Yuqi Pang, Xunyu Liu and Xiaotian Xu
Original Research
With the development of the automobile industry, the extensive use of automobiles is a key factor in the global energy crisis and environmental pollution, and the clean and environmentally friendly characteristics of electric vehicles have become an ideal means to deal with these two major problems. Connecting household electric vehicles to the home will not only affect the distribution network, but also adversely affect the home electricity network. Therefore, it is necessary to connect electric vehicles to household charging load for quantitative analysis, so as to design energy control methods for electric vehicles to connect to households, and minimize the adverse effects of electric vehicles connected to household power grids. First of all, this article analyzes the uncertainty of electric vehicle access to the grid. After considering the random characteristics of electric vehicle charging load, an electric vehicle charging load model is built based on Monte Carlo simulation. Secondly, according to the electric vehicle charging load power curve obtained by the above method, combined with the daily load probability model of the grid, a household electricity model is established. Finally, based on the Particle Swarm Optimization(PSO), a family energy control method is proposed, and the optimization goal is to minimize the daily load fluctuation of the family, so as to minimize the impact of electric vehicles connected to the grid.
American Journal of Electrical and Electronic Engineering. 2020, 8(3), 80-83. DOI: 10.12691/ajeee-8-3-2
Pub. Date: July 29, 2020
4133 Views517 Downloads
by Xunyu Liu, Xiaotian Xu, Yu Qi Pang and Xinyuan Zhang
Original Research
In terms of large-scale integration of renewable energy into the grid, DC grid technology has obvious advantages over traditional AC grids. The good operation of a DC grid depends on effective control of power flow distribution. However, the adjustment of the bus voltage and its total power by the converter station alone cannot guarantee the control of all branches of the power grid. Therefore, it is necessary to install a DC power flow controller to achieve a reasonable distribution of line flow. This article is aimed at the multi-terminal DC grid, based on the basic power flow calculation method, considers the influence of the power flow controller on the DC grid power flow calculation and adds the influence to the calculation, changing the power equation or resistance parameters of the line, thereby realizing the power flow calculation The grid power flow calculation of the controller is realized by programming in MATLAB. The proposed calculation method can lay the foundation for the power flow optimization and stable operation of the DC grid.
American Journal of Electrical and Electronic Engineering. 2020, 8(3), 73-79. DOI: 10.12691/ajeee-8-3-1
Pub. Date: July 29, 2020
4726 Views501 Downloads