1550nm光发系统在多村联网中的应用

乡村有线电视的特点是各村之间相距较远，分布广而散，致使网络干线长，网络故障相对容易发生，维护技术人员有限，维修工作难度相对较大。

1310nm和1550nm光发系统在乡镇光缆联网中的应用比较

为了在“本世纪末实现村村通广播电视”,各地都在采用光缆进行联网。商丘市有线电视台自1999年3月开始在市属两区乡镇实施光缆联网工作,在这个过程中是采用1310nm系统还是采用1550nm系统,这也正是各地进行乡镇光缆联网时共同面对的问题,对此我们从以下几个方面进行了比较。

1550光发系统在石河子农村改造中的应用

本文针对农村网络实现双向数字化改造建设思路,1550nm有线电视干线传输网络。

分布式光伏发电系统的监控配置方案研究

随着普通能源的不可再生和环境问题的日益严重,新能源的开发越来越受到重视。在众多新能源替代品中,太阳能以其独特的优势成为新的发展方向。本文主要研究基于太阳能电池板的太阳能三相全桥并网逆变器并网系统,在此基础上,通过分布式光发电力系统现状的调研,总结分布式光发电力系统应用中存在的问题,为分布式光发电力监控系统的应用提供理论依据和技术支持。在分布式光伏设备监控系统方面,系统研究了分布式光伏设备监控系统中母线箱故障报警技术和电站中光伏组件异常衰减率报警技术。监控系统功能完善,提高了光伏发电的稳定性和可靠性。

Short-term prediction of photovoltaic power generation based on LMD-EE-ESN with error correction

Considering the instability of the output power of photovoltaic(PV)generation system,to improve the power regulation ability of PV power during grid-connected operation,based on the quantitative analysis of meteorological conditions,a short-term prediction method of PV power based on LMD-EE-ESN with iterative error correction was proposed.Firstly,through the fuzzy clustering processing of meteorological conditions,taking the power curves of PV power generation in sunny,rainy or snowy,cloudy,and changeable weather as the reference,the local mean decomposition(LMD)was carried out respectively,and their energy entropy(EE)was taken as the meteorological characteristics.Then,the historical generation power series was decomposed by LMD algorithm,and the hierarchical prediction of the power curve was realized by echo state network(ESN)prediction algorithm combined with meteorological characteristics.Finally,the iterative error theory was applied to the correction of power prediction results.The analysis of the historical data in the PV power generation system shows that this method avoids the influence of meteorological conditions in the short-term prediction of PV output power,and improves the accuracy of power prediction on the condition of hierarchical prediction and iterative error correction.

Photosystem Development in Dark-grown Lotus (Nelumbo nucifera) Seedlings

It is well known that no chlorophyll synthesis and photosystem biogenesis have been detected in dark-grown angiosperm seedlings. However, in this report, we showed that both PS II and PS I could be formed in dark-grown lotus (Nelumbo nucifera Gaertn.) seedlings. Lots of evidence were given: First I during the dark-grown period, the single fluorescence emission peak at 679 nm in lotus embryo red-shifted and transformed into the normal PS II fluorescence emission; Simultaneously, PS I fluorescence emission at 730 nm appeared and increased obviously; Second, with partial denaturing SDS-PAGE method, PS I chlorophyll-protein complex could be clearly separated from 10 days dark-grown lotus seedlings; Third, the existence of Lhca1 was also proved by Western blots. Moreover, measurements of electron transfer rate demonstrated that both PS II and PS I core in dark-grown lotus seedlings were photochemically active.

Phylogenetic Relationship of the Firefly,Diaphanes pectinealis(Insecta,Coleoptera,Lampyridae) Based on DNA Sequence and Gene Structure of Luciferase

Diaphanes is the fourth largest genus in Lampyridae, but no luciferase gene from this genus has been reported. In this paper, by PCR amplification of the genomic DNA, the luciferase gene of Diaphanes pectinealis, which is the first case from Diaphanes, was identified and sequenced. The luciferase gene from D. pectinealis spans 1958 base pairs （bp） from the start to the stop codon, including seven exons separated by six introns, and encoding a 547-residuelong polypeptide. Its deduced amino acid sequence showed high protein similarity to those of the Lampyrini tribe （93 - 94% ） and the Cratomorphini tribe （92%）, while low similarity was found with the North American firefly Photinus pyralis （83%） of the Photinini tribe within the same subfamily Lampyrinae. The phylogenetic analysis performed with the deduced amino acid sequences of the luciferase gene further confirms that D. pectinealis, Pyrocoelia, Lampyris, Cratomorphus, and Photinus belong to the same subfamily Lampyrinae, and Diaphanes is closely related to Pyrocoelia, Lampyris, and Cratomorphus. Furthemore, the phylogenetic analysis based on the nucleotide sequences of the luciferase gene indicates Diaphanes is a sister to Lampyris. The phylogenetic analyses are partly consistent with morphological （Branham ＆ Wenzel, 2003） and mitochondrial DNA analyses （Li et al, 2006）.

MECHANISM OF CHANGE IN THE CATION INDUCED EXCITA TION ENERGY DISTRIBUTION BETWEEN PSⅡ AND PSⅠ IN THE CHLOROPLAST MEMBRANE FROM ZOSTERA MARINA *

The interrelations between thylakoid polypeptide components and Mg 2+ induced Chl a fluorescence and thylakoid surface charge changes were investigated in Zostera marina chloroplasts treated with Ca 2+ and trypsin. It was observed that:1. The increase of Mg 2+ induced PSⅡ fluorescence intensity was closely related to the decrease of Mg 2+ induced surface charge density of the thylakoid membrane in the normal chloroplast; 2. Removal of the 32~34 kD polypeptides of the thylakoid surface by Ca 2+ extraction of the chloroplast did not affect the Mg 2+ induced phenomena; 3. If the Ca 2+ treated chloroplast was further digested by trypsin to remove the 26 kD polypeptide of the membrane surface, the Mg 2+ induced phenomena disappeared completely. These results clearly indicated that the 26 kD polypeptide of thylakoid surface is the specific acting site of the cation that induced these two correlated phenomena in the chloroplast from Zostera marina. The mechanism on the regulating effect of the cation on excitation energy distribution between PSⅡ and PSⅠ was discussed.

POWER GENERATION POTENTIAL OF BIPV APPLICATION IN CHINA

This paper discusses the potential and prospect of building-integrated photovoltaics (BIPV) for solar electrical power generation in China.The BIPV technology has been identified as the most economical renewable energy resource to contribute to world electrical energy demand for protecting environment from reduced fossil fuel consumption.The available solar energy resource of 14 cities and the potential power generation from PV claddings in buildings in China were estimated.The economical analysis of BIPV application is discussed.It is found that the potential is significant and the government should play an important role in its development.

Cultural and luminescent Conditions of a Marine luminous Bacterium

Study of marine noctilucence in marine is important to fishery, environmental monitoring and military affairs. A luminous bacterial strain D2 was isolated from the marine sediment samples collected near Donghai Island in Zhanjiang, China. The primary cultural and luminescent conditions of luminous bacterium D2 which was identified as Vibrio sp. were determined in liquid culture. The results showed that pH 7.0, 35 ℃, with 2.0 % NaCI, were the best growth conditions, and pH5 - 6, 20℃, OD600 0.08, with 3.0 % NaCI, were the optimal luminescent conditions.

A Real-time Modeling of Photovoltaic Array

This paper mainly aims at the modeling problem of the photovoltaic (PV) array with a 30 kW PV grid-connected generation system. An iterative method for the time-varying parameters is proposed to model a plant of PV array. The relationship of PV cell and PV array is obtained and the solution for PV array model is unique. The PV grid-connected generation system is used to demonstrate the effectiveness of the proposed method by comparing the calculated values with the actual output of the system.

Design of hybrid damping controller based on multi-target gravitational search optimization algorithm in a multi-machine power system with high penetration of PV park

A mathematical approach was proposed to investigate the impact of high penetration of large-scale photovoltaic park(LPP) on small-signal stability of a power network and design of hybrid controller for these units.A systematic procedure was performed to obtain the complete model of a multi-machine power network including LPP.For damping of oscillations focusing on inter-area oscillatory modes,a hybrid controller for LPP was proposed.The performance of the suggested controller was tested using a 16-machine 5-area network.The results indicate that the proposed hybrid controller for LPP provides sufficient damping to the low-frequency modes of power system for a wide range of operating conditions.The method presented in this work effectively indentifies the impact of increased PV penetration and its controller on dynamic performance of multi-machine power network containing LPP.Simulation results demonstrate that the model presented can be used in designing of essential controllers for LPP.

High Efficiency PCS with Scan-Type MPPT Control for a Grid-Connected PV Power Generation System

For a standalone PV （photovoltaic） power generation system, the author previously proposed a new MPPT （maximum power point tracking） control method in which the I-V characteristics are scanned with a detection interval control that operates at specified intervals and monitors the maximum power point. The author has obtained satisfactory results using this new MPPT control method. This paper investigates the application of the new MPPT control method for a PCS （power conditioning system） in a grid-connected type PV power generation system. The experimental results clearly demonstrate that the developed PCS offers outstanding effectiveness in tracking the maximum power point in partially shaded environments.

Study on the Photovoltaic System with MPT and Supercapacitors

The paper makes survey of operating principle of power management of photovoltaic system with supercapacitors and a maximum power tracker （MPT） control to achieve the maximum efficiency. Supercapacitors are well suited to replace classical batteries and conventional capacitors in photovoltaic applications to improve a dynamic behaviors and life-time. It describes the advantages of a supercapacitors solution and shows the results of comparison with convenient batteries. The paper presents different topologies of basic photovoltaic concepts with dc-dc converters and supercapacitors according to the power dimension. The mathematical equations describing the photovoltaic cells, temperature analyses and mathematical solution of MPT are shown in the paper and supported by measurements. The mathematical models were applied in the design of 50 W and 6 kW photovoltaic sources with MPT and supercapacitors. Both models were verified using experimental measurements on the photovoltaic setup.

Research of Confocal Laser Induced Fluorescence Detection System for Micro-fluidic Chip

The characteristics such as signal noise ratio（SNR） and sensitivity of the fluorescence detection system for micro-fluidic chip influence the performance of the whole system extremely. The confocal laser induced fluorescence detection system is presented. Based on the debugging of optical and circuit modules, the results of detecting the samples are given and analyzed theoretically, and the improved project is put forward.

Transient Stability Analysis of Power System with Photovoltaic Systems Installed

The impact of large-scale grid-connected PV （photovoltaics） on power system transient stability is discussed in this paper. In response to an increase of PV capacity, the capacity of conventional synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence, the power system transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the potential impact of significant PV penetration on the transient stability is assessed by a numerical simulation using PSCAD/EMTDC.

Transient Stability Assessment of Synchronous Generator in Power System with High-Penetration Photovoltaics

As photovoltaic （PV） capacity in power system increases, the capacity of synchronous generator needs to be reduced relatively. This leads to the lower system inertia and the higher generator reactance, and hence the generator transient stability may negatively be affected. In particular, the impact on the transient stability may become more serious when the considerable amounts of PV systems are disconnected simultaneously during voltage sag. In this work, the generator transient stability in the power system with significant PV penetration is assessed by a numerical simulation. In order to assess the impact from various angles, simulation parameters such as levels of PV penetration, variety of power sources （inverter or rotational machine）, and existence of LVRT capability are considered. The simulation is performed by using PSCAD/EMTDC software.

Research on Testing System for Three-dimensional Distribution of Luminous Intensity of LED

In terms of asymmetrical three-dimensional distribution(ID) of luminous intensity(LI) of light-emitting-diode(LED),a testing system was conducted in this study. Design and principle of the testing system were introduced. 31 photometers were placed on a concentric circle,and all of them were used to gather LI data of LED at the same time. The data acquisition card(DAC) was used to gather multichannel data and controlled motor. Experimental results indicated that the testing system had achieved the goal of testing three-dimensional distribution of LI. And each parameter could meet the requirements of industrial production and measurement.

Design and Implementation of a Digitally Controlled Photovoltaic System Using Series Connected Buck Converters

In PV （photovoltaic） power systems, a MPPT （maximum power point tracking） algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from complex physical environments in such PV power systems. To minimize the degradation of performances caused by these conditions, and therefore adding reliability and robustness, this paper presents an implementation of a digitally controlled system using a topology based on series connected DC-DC buck converters for a stand-alone PV power system applications, operating with local and autonomous controls, to track the maximum power points of PV modules in non ideal conditions. Simulations are carried out by using C-MEX S-functions under MATLAB-SIMULINK environment. A PV system of 1.44 kWc is described and simulation results are presented.