Applied Mechanics and Materials Vols. 716-717

Abstract: Aim at the development and realization of SVPWM three-phase inverter control by DSP, the concrete of method and technology by DSP of SVPWM control is given, the complete hardware circuit and DSP control program is designed, the core of source program and setting method of DSP register are given. The results show that, voltage waveform output from SVPWM three-phase inverter is stability and reliability, output frequency with high control precision. The paper has good applied value for engineering development of inverter.

Abstract: This paper is focused on technical features of large-capacity distributed power generation and takes the example 33 in distribution system as illustration. What is more, the paper analyzes how injection capacity and access locations of distributed generation can affect voltage and network losses. The analysis carries out the trend that indicators changing regarding to change in injection capacity and access locations. Take a typical distribution network of 10kV with distributed power for example, and analysis what affect will happen to the access point upstream, downstream and adjacent current protection that brings by the distributed generation. It is concluded that the main factor that restrains distributed power capacity in photovoltaic power generation is voltage fluctuation and the relay operation of distributed system.

Abstract: At present, China has built a number of DG (distributed power generation) demonstration projects as part of intelligent cities, intelligent business parks, university campuses and residential areas. The interaction mechanism, among DGs-especially those with energy storage, the users and the distribution grid need to be clear; i.e. how to unify the coordination among solar power systems, small wind power generation systems, the battery energy reserve systems, and electrical vehicles, so as to optimize resources allocation, cut peak and compensate trough loads; how to enable future homes and business users has more flexibility, controllability on electricity usage thus to advance the technology development in the field of electricity usage. The above mentioned problems can be solved smoothly by researching on the comprehensive use of modern power electronic technologies, communication technologies, computer and network technologies, advanced sensor and measurement & control technology, to combine them together for monitoring, protection control, cloud computing , and management of power supply department for active distribution network after DG access, to constitute the comprehensive dispatching system based on the DG of cloud computing. Dispatching of DG for distance dispersion location and a huge number of terms, to based on the cloud computing is very cost-effective, and it is worthy of further study and application.

Abstract: The study on characteristics of transformer vibration caused by GIC is the foundation of studies on transformer noise caused by GIC, location selection of monitoring vibration and noise. In this study, the characteristics of low-frequency vibration of the core of single phase transformer sets caused by GIC have been analyzed through building mathematical models and experimental analysis. The results show that when DC bias occurs the vibration signals contain 50 Hz and 150 Hz vibration. With the degree of DC bias the 50 Hz vibration grows by linear increase and 150 Hz vibration grows by square increase. Affected by GIC, the 50 Hz and 150 Hz vibration waveform’s phase changes with alternate 0 andπ. The characteristics of 50 Hz and 150 Hz vibration discriminate between core vibration caused by GIC and HVDC grounding currents. This study has significance for vibration monitoring of transformer faults, and can assist in determining the level of GIC.

Abstract: This paper summarizes the position detection and location estimation method, and it has a analysis of the position type alarm classification and related technical problems based on that; Position type alarm system related control algorithm is proposed and the related design, combined with the actual design of the circuit debugging steps and specific experimental parameters is given, the practice shows that the stability and reliability of design.

Abstract: Adaptation evaluation index system is established according to the influences brought by the distributed generations (DGs) interconnected with the distribution network. Evaluation indicators are proposed to reflect the operating conditions of distribution lines, switches and other important devices of distribution network. Combine Analytic Hierarchy Process (AHP) and Principal Component Analysis (PCA) method is used to determine the weights of the evaluation indicators. Whereby obtain the comprehensive evaluation results of distribution equipment adaptation to DGs integration. A study of a practical grid is made in the cases of the DGs centralized integration, decentralized integration, and without DGs. The simulated result shows that a large number of DGs connected with the distribution network would deteriorate a majority of the equipment operating indicators, especially to the indexes related to switches and protection devices. Meanwhile, when a distribution network is connected into the same capacity of DGs, the distribution equipment would show a better adaptation to DGs' decentralized integration.

Abstract: This paper propose the power quality evaluation index used to evaluate the impacts of the different distributed generation grid-connected modes made on power quality in the distribution network. Simulation example is built on the basis of a real distribution network as prototype using DigSilent software. Then Comparative analysis of the impacts on voltage deviation, harmonic and short duration voltage fluctuations of decentralized integration mode and centralized integration mode are made. The simulation results show that the centralized mode has more influences on the distribution network power quality, especially when there is power generated by distributed generations flowing to the main grid.

Abstract: In digital signal processing system and microcomputer system, often need to high speed DSP devices and large-scale ASIC, FPGA to design and development, in these systems, the high requirement of the precision of the power module and power supply current, power supply module design will directly affect the stability of the whole system. In addition, the power supply module is usually low voltage large current of DC/DC converter, the requirement of efficiency is very high, generally over 90%. This paper introduces the FPGA based on TI company's TPS54810 power supply with low voltage large current DC/DC converter module design, this paper introduces in detail the external compensation of synchronous buck DC/DC converter power supply circuit design methods.

Abstract: Near field communication of HF radio is in the form of surface wave propagation. The propagation loss increases with the increase distance, but there is a certain regular. In addition to this, the communication quality relates to the background noise. In order to find the relationship between them, we obtain the relationship between effective communication distance and background noise through theoretical derivation in the 2FSK system. Simulation results show that the effective communication distance is shorter with the increase of carrier frequency and the decline of the ground conductivity. And the simulation results can play a guiding role for the estimation of the HF radio’s effective communication distance.

Abstract: This paper addresses the problem of the effect of different antenna layouts on the capacity of massive multiple-input multiple-output (MIMO) system capacity. Based on the narrow-band, flat fading channel model, the effect of scattering environment and antenna layout are considered by incorporating the power azimuth spectrum (PAS) and the array manifold vector. Under the same antenna aperture, six antenna layouts are investigated among which the UCA yields the best capacity while ULA yields the lowest capacity. The more symmetric the antenna geometry is, the better capacity performance it has.