嵌入式换流站设计优化研究

为了充分发挥嵌入式直流技术的特点和优势,助力新型电力系统的建设。本文对嵌入式换流站的直流拓扑接线、换流变选型、平面布置等开展了优化研究。提出采用对称单极接线,优化直流功率运行范围、采用SVG代替常规交流滤波器、采用单相三绕组换流变压器,换流变与阀厅解耦布置等优化方案,降低了嵌入式换流站的工程造价及难度,有助于嵌入式直流的推广与应用。

基于分层布局思想的配电网拓扑图自动生成算法

拓扑图自动生成算法是配电网拓扑接线图自动成图的核心。为此,详细阐述了拓扑图自动生成算法的基本思路,该算法的核心是采用深度优先遍历(depth first search,DFS)算法搜索两点之间的最大距离。同时提出了分层布局、综合实现的成图思想,其具体实现分为3层:1)确定单条馈线的拓扑布局数组;2)确定两两变电站之间的拓扑布局数组;3)确定所有变电站之间的拓扑布局数组。将两两变电站之间的布局数组填充至所有变电站的布局数组中,可以得到配电网全网的布局数组,按照全网布局数组所确定的各变电站和各设备的坐标位置和互联信息,生成全网的拓扑接线图。该方法解决了直接一次性求取所有配电网设备在拓扑接线图中的坐标所导致的求解过程高度复杂甚至无解的问题,有效避免了交叉,大大减少了成图时间。最后,通过工程实际应用,验证了该算法的有效性和适用性。

“沙戈荒”新能源大基地多种汇集升压方式技术经济优选

建设以沙漠、戈壁、荒漠地区为重点的新能源大基地是我国推进“碳达峰、碳中和”战略的重要举措。结合工程实际,对风光大基地多级电压拓扑接线方案进行较全面的梳理,通过工程技术经济比对给出适用于新时代“沙戈荒”新能源大基地的汇集升压方式,对未来同类工程研究与实践具有一定参考意义。

A Position-Based Handoff Scheme in WAVE Systems

IEEE 802.11p has been proposed to extend the application of IEEE 802.11 to Wireless Access fast fading Vehicular Environments (WAVE).Due to the high velocities of vehicles and thus the inconstant topology of networks,it is extremely difficult to maintain communications without handoff in an Internet of Vehicles (IoV).Hence,fast handoff from one roadside unit (RSU) to another is necessary.Although some solutions have been given in IEEE 802.11r and 802.11f standards,the handoff latency is still as high as about 50 ms when adopting them.To address this issue in WAVE systems,a novel position-based handoff (PHO) scheme is proposed in this paper.In PHO scheme,the triggering of the handoff is accomplished by the location information of a vehicle instead of the power level of the received signal.Both the handoff process and latency of PHO scheme are analyzed.Finally,to verify the analytical results,simulations were conducted to date the effectiveness of the proposed PHO scheme.

One-Branch Zero-IF Wireless Receiver Topology with Multiphase Local Oscillator

This paper proposes a one-branch zero-IF receiver topology, which samples the I and Q signals of the modulated RF carrier with one signal path by means of a multiphase local oscillator. The suggested one-branch re- ceiver works without matching problem, and it is also capable of cancelling out the flicker noise and DC-offset when the local oscillator is configured to the four-phase mode. The one-branch receiver saves much area and power com- pared with the traditional two-branch ones. All of the advantages above make the one-branch receiver topology a promising architectural candidate for low-power and low-cost RF CMOS receiver designs. Keywords： RF CMOS; zero-IF; flicker noise; image rejection; low-power; IQ matching

A Frameless Network Architecture for the Way Forward of C-RAN

The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network topology for a multi-tier Heterogeneous Network(Het Net) and ultra-dense network is proposed. The FNA network topology modeling is researched with centralized processing and distributed antenna deployments. The Antenna Element(AE) is released as a new dimensional radio resource that is included in the centralized Radio Resource Management(RRM) processes. This contributes to the on-demand user-centric serving-set associations with cell-edge effect elimination. The Control Plane(CP) and User Plane(UP) separation and adaptation are introduced for energy efficiency improvements. The centralized RRM and different optimization goals are discussed for fully exploring the merits from the centralized computing of C-RAN. Considering the complexity, near-optimal approaches for specific users' Quality-of-Service(Qo S) requirements are addressed. Finally, based on the research highlighted above, the way forward of C-RAN evolution is discussed.

Magnetically Controlled Electronic Transport Properties of a Ferromagnetic Junction on the Surface of a Topological Insulator

We have investigated the transport properties of the Dirac fermions through a ferromagnetic barrier junction on the surface of a strong topologicM insulator. The current-voltage characteristic curve and the tunneling conductance are calculated theoretically. Two interesting transport features are predicted： observable negative differential conductances and linear conductances tunable from unit to nearly zero. These features can be magnetically manipulated simply by changing the spacial orientation of the magnetization. Our results may contribute to the development of high-speed switching and functional applications or electricalIy controlled magnetization switching.