虚拟同步控制下双馈风电机组传动链动态特性分析

虚拟同步发电机针对(VSG)控制对风电机组机械结构影响缺乏认知问题,开展VSG控制下双馈风电机组(DFIG)传动链动态特性分析研究。建立计及传动链柔性的DFIG模型,并通过转子侧变流器实现DFIG的VSG控制。考虑电网频率冲击扰动与风速持续扰动两种情况,通过所建模型仿真对比VSG控制和传统矢量控制下DFIG传动链动态特性,并分别从时域和频域分析VSG关键控制参数对传动链动态特性的影响。结果表明,DFIG运行于VSG控制模式时,电网频率冲击扰动在其传动链激励出大幅度的冲击性自由扭振,风速持续扰动引发其传动链出现大幅度的持续性受迫扭振和幅度较小的持续性自由扭振,且VSG关键控制参数对自由扭振强度影响显著。

考虑新能源消纳与低碳排放的多电-气互联系统合作博弈

双碳目标下为提高新能源消纳量和降低碳排放量,建立考虑灵活资源和碳捕集的多电-气互联系统低碳合作博弈模型。该模型以实现大量灵活设备参与调度情况下,将低碳运行效益最大化,同时提高系统能源综合利用率;并采用非对称纳什议价方式在多区域间博弈合理分配各系统利益,以提高各子系统主动参与合作机制的积极性。考虑到所建模型为凸优化问题,采用分布式ADMM算法求解,具有良好的收敛性和鲁棒性。算例分析表明,合作博弈机制能实现不同区域和不同类型灵活设备的电能协调优化调度,提高系统风电、光伏等新能源发电的接纳能力,同时可有效降低区域综合能源系统的净成本和碳排放量。

计及期权合约和交易路径的省间优化出清模型与算法研究

针对省间电力交易计算的日趋复杂且效率缓慢等问题,结合省间主要输电线路特点,提出了基于图论法的交易路径优化方法;将期权模式引入合约市场交易中有效规避电价波动风险,提高参与者应对市场变化的能力。为了降低省间交易的计算难度、提高社会效益,以社会福利最大化为目标,构建了计及期权合约和交易路径的省间优化出清模型与算法。通过算例,验证了所提优化出清模型及期权合约的有效性和适用性。

含风电场的可用输电能力改进布谷鸟算法

随着风电渗透率的提高,电网不确定性因素急剧增加,传统可用输电能力计算方法已难以满足现有电网对安全、稳定、经济、实时运行等方面的要求。为此,利用拉丁超立方采样生成具有相关性的风速样本,建立可用输电能力的概率最优潮流模型。为保证计算精度和速度,构建基于混沌初始化、变异算子和动态发现概率的改进布谷鸟搜索算法。通过IEEE-30节点系统仿真分析,评估风速相关性对可用输电能力的影响,证明了改进算法的正确性和有效性。

考虑省间现货交易路径的ATC计算方法研究

随着电力市场和特高压的快速发展,电网可用空间及市场开展的边界难以通过人工经验判断,有必要研究省间现货交易的可用输电容量计算方法。针对该问题,结合电力现货市场特点、跨区域输电定价机制和电气距离,构建了考虑电气特性的省间交易网络模型,提出了基于遗传算法的省间交易路径寻优优化方法;与传统高低匹配出清方式下形成的交易路径进行对比,分析验证其可行性,寻得最优交易路径;将可用输电能力(available transfer capability, ATC)计算方法与交易路径相结合,以最优交易路径上的成交电量进行最优潮流计算,得到省间现货市场下基于交易路径的可用输电容量。

基于元胞自动机与多层前馈神经网络的电力信息物理融合系统安全评估模型

电力信息系统故障可能引起物理系统运行安全问题,因此有必要对信息安全故障跨空间传播行为进行建模分析。根据电力信息系统故障传播机制,统一将智能监控设备与通信网络节点的状态量抽象为数据节点。在此基础上,通过分析数据节点状态变化与转移的量化关系,建立了基于元胞自动机与多层前馈神经网络的数据节点安全评估模型。利用多层前馈神经网络挖掘元胞自动机的演化规则,并计算得出数据节点故障跨空间随机传播概率。最后,以3机9节点系统为例,通过仿真验证了评估模型的有效性,为研究电力信息物理融合系统安全评估提供了新思路。

简析农业生态环境保护与农业可持续发展

随着我国逐渐建立资源节约型、环境友好型社会,农业生态环境保护和农业可持续发展都初见成效。但是从目前的发展状态中可以看出,农业生态环境保护和农业的可持续发展在实施过程中还存在一定的问题,农业生态的恶劣环境依然对人们的生产生活造成严重影响。因此,要想保护人们赖以生存的家园,实现农业的可持续发展,促进经济和生态共同发展,就要对农业生态环境加以保护。文章就农业生态环境保护展开了讨论,深度探讨了农业生态环境保护促进农业可持续发展的有效途径。

计算机软件工程的管理及应用

从当前计算机技术的发展势头能够看到,对社会发展产生了深远影响,计算机软件工程管理工作实施对计算机领域的发展有着促进作用,做好计算机软件工程管理工作就显得比较重要。本文主要就计算机软件工程的管理和应用从理论层面进行深化探究,希望能对计算机软件工程有更多的认识。

Improvement of orbit determination for geostationary satellites with VLBI tracking

China’s COMPASS satellite navigation system consists of five or more geostationary (GEO) satellites.The roles of GEO satellites are to improve the regional user’s positioning accuracy and provide the continuous Radio Determination Satellite Service.The motion of GEO satellites relative to a ground tracking station is almost fixed,and regular orbit maneuvers are necessary to maintain the satellites’ allocated positions above the equator.These features present difficulties in precise orbit determination (POD).C-band ranging via onboard transponders and the L-band pseudo-ranging technique have been used in the COMPASS system.This paper introduces VLBI tracking,which has been successfully employed in the Chinese lunar exploration programs Chang’E-1 and Chang’E-2,to the POD of GEO satellites.In contrast to ranging,which measures distances between a GEO satellite and an observer,VLBI is an angular measurement technique that constrains the satellite’s position errors perpendicular to the satellite-to-observer direction.As a demonstration,the Chinese VLBI Network organized a tracking and orbit-determination experiment for a GEO navigation satellite lasting 24 h.This paper uses the VLBI delay and delay-rate data,in combination with C-band ranging data,to determine the GEO satellite’s orbit.The accuracies of the VLBI delay and delay rate data are about 3.6 ns and 0.4 ps/s,respectively.Data analysis shows that the VLBI data are able to calibrate systematic errors of the C-band ranging data,and the combination of the two observations improves orbit prediction accuracy with short-arc data,which is important for orbital recovery after maneuvers of GEO satellites.With the implementation of VLBI2010,it is possible for VLBI to be applied in the COMPASS satellite navigation system.

Orbit determination for Chang'E-2 lunar probe and evaluation of lunar gravity models

The Unified S-Band （USB） ranging/Doppler system and the Very Long Baseline Interferometry （VLBI） system as the ground tracking system jointly supported the lunar orbit capture of both Chang＇E-2 （CE-2） and Chang＇E-1 （CE-1） missions. The tracking system is also responsible for providing precise orbits for scientific data processing. New VLBI equipment and data processing strategies have been proposed based on CE-1 experiences and implemented for CE-2. In this work the role VLBI tracking data played was reassessed through precision orbit determination （POD） experiments for CE-2. Significant improve- ment in terms of both VLBI delay and delay rate data accuracy was achieved with the noise level of X-band band-width syn- thesis delay data reaching 0.2-0.3 ns. Short-arc orbit determination experiments showed that the combination of only 15 min＇s range and VLBI data was able to improve the accuracy of 3 h＇s orbit using range data only by a 1-1.5 order of magnitude, confirming a similar conclusion for CE-1. Moreover, because of the accuracy improvement, VLBI data was able to contribute to CE-2＇s long-arc POD especially in the along-track and orbital normal directions. Orbital accuracy was assessed through the orbital overlapping analysis （2 h arc overlapping for 18 h POD arc）. Compared with about 100 m position error of CE-l＇s 200 kin x 200 km lunar orbit, for CE-2＇s 100 km x 100 km lunar orbit, the position errors were better than 31 and 6 m in the radial direction, and for CE-2＇s 15 km^100 km orbit, the position errors were better than 45 and 12 m in the radial direction. In addi- tion, in trying to analyze the Delta Differential One-Way Ranging （ADOR） experiments data we concluded that the accuracy of ADOR delay was dramatically improved with the noise level better than 0.1 ns and systematic errors better calibrated, and the Short-arc POD tests with ADOR data showed excellent results. Although unable to support the development of an independent lunar gravity model, the tracking data of CE-2 provided evaluations of different lunar gravity models through POD. It is found that for the 100 km x 100 km lunar orbit, with a degree and order expansion up to 165, JPL＇s gravity model LP165P did not show noticeable improvement over Japan＇s SGM series models （100x100）, but for the 15 kmxl00 km lunar orbit, a higher de- gree-order model can significantly improve the orbit accuracy.

Precise positioning of the Chang'E-3 lunar lander using a kinematic statistical method

A kinematic statistical method is proposed to determine the position for Chang'E-3(CE-3) lunar lander.This method uses both ranging and VLBI measurements to the lander for a continuous arc,combing with precise knowledge about the motion of the moon as provided by planetary ephemeris,to estimate the lander's position on the lunar surface with high accuracy.Accuracy analyses are carried out with simulation data using the software developed at Shanghai Astronomical Observatory in this study to show that measurement errors will dominate the position accuracy.Application of lunar digital elevation model(DEM) as constraints in the lander positioning is also analyzed.Simulations show that combing range/doppler and VLBI data,single epoch positioning accuracy is at several hundred meters level,but with ten minutes data accumulation positioning accuracy is able to be achieved with several meters.Analysis also shows that the information given by DEM can provide constraints in positioning,when DEM data reduce a 3-dimensional positioning problem to 2-dimensional.Considering the Sinus Iridum,CE-3 lander's planned landing area,has been observed with dedicated details during the CE-1 and CE-2 missions,and its regional DEM model accuracy may be higher than global models,which will certainly support CE-3's lander positioning.