Optimum Sizing and Siting of an Embedded Solar Photovoltaic Generation: A Case Study of 33 kv Sub-Transmission Network at Tarkwa, Ghana

The interconnection of Solar PV to the Tarkwa Bulk Supply Point (BSP) has become necessary in order to provide additional capacity to meet the ever-increasing demand of Tarkwa and its environs during the day. The Solar PV Plant will support the Tarkwa BSP during the day. In this study, a grid impact analysis for the integration of Solar PV plant at three points of common coupling (PCC) at Tarkwa Bulk Supply Point’s (BSP) 33 kV network of the Electricity Company of Ghana was carried out. The three PCCs were Tarkwa BSP, Ghana Australia Gold (GAG) Substation and Darmang Substation. Simulations and detailed analysis were carried out with the use of CYME Software (Cyme 8.0 Rev 05). The Solar PV was integrated at varying penetration levels of 9 MWp, 11 MWp, 14 MWp, 16 MWp, 18 MWp, 20 MWp and 23 MWp (representing penetration levels of 40%, 50%, 60%, 70%, 80%, 90% and 100%, respectively) of the 2020 projected light demand of Tarkwa BSP 25.15 MVA network at an average power factor of 0.903. From the study, the optimum capacity of Solar PV power that could be connected is 9 MWp at an optimum inverter power factor of 0.94 lagging, and the GAG Substation was identified as the optimal location. The stiffness ratio at the optimal location was determined as 41.9, a figure which is far greater than the minimum standard value of 5, and gives an indication of very little voltage control problems in the operation of the proposed Solar PV interconnection. The integration of the optimum 9 MW Solar PV Plant to the Tarkwa network represents an additional 12.77% capacity, decreased the technical losses by 7.76%, and increased the voltage profile by 1.97%.

An Integrated Image Task Planning in Satellite Networks:From Instruction Release and Observation Perspective

The unreasonable observation arrangements in the satellite operation control center(SOCC)may result in the observation data cannot be downloaded as scheduled.Meanwhile,if the operation instructions released by the satellite telemetry tracking center(STTC)for the on-board payloads are not injected on the specific satellites in time,the corresponding satellites cannot perform the observation operations as planned.Therefore,there is an urgent need to design an integrated instruction release,and observation task planning(I-IRO-TP)scheme by efficiently collaborating the SOCC and STTC.Motivated by this fact,we design an interaction mechanism between the SOCC and the STTC,where we first formulate the I-IRO-TP problem as a constraint satisfaction problem aiming at maximizing the number of completed tasks.Furthermore,we propose an interactive imaging task planning algorithm based on the analysis of resource distribution in the STTC during the previous planning periods to preferentially select the observation arcs that not only satisfy the requirements in the observation resource allocation phase but also facilitate the arrangement of measurement and control instruction release.We conduct extensive simulations to demonstrate the effectiveness of the proposed algorithm in terms of the number of completed tasks.

A Least-squares-based Iterative Method with Better Convergence for PF/OPF in Integrated Transmission and Distribution Networks

The limitations of the conventional master-slavesplitting(MSS)method,which is commonly applied to power flow and optimal power flow in integrated transmission and distribution(I-T&D)networks,are first analyzed.Considering that the MSS method suffers from a slow convergence rate or even divergence under some circumstances,a least-squares-based iterative(LSI)method is proposed.Compared with the MSS method,the LSI method modifies the iterative variables in each iteration by solving a least-squares problem with the information in previous iterations.A practical implementation and a parameter tuning strategy for the LSI method are discussed.Furthermore,a LSI-PF method is proposed to solve I-T&D power flow and a LSIheterogeneous decomposition(LSI-HGD)method is proposed to solve optimal power flow.Numerical experiments demonstrate that the proposed LSI-PF and LSI-HGD methods can achieve the same accuracy as the benchmark methods.Meanwhile,these LSI methods,with appropriate settings,significantly enhance the convergence and efficiency of conventional methods.Also,in some cases,where conventional methods diverge,these LSI methods can still converge.

Challenges for beyond 5G:ultra-densification of radio access network

Ultra-densification of radio access network(RAN)is a key to efficiently support the exponentially growing mobile data traffic in 5 G era.Furthermore,extremely high frequency band like mm Wave band was utilized to solve the bandwidth shortage problem.However,untra-dense reusing the same radio resource produced severe interference.And the mm Wave link was very harsh due to frequent blockage by obstacles.Therefore a new RAN architecture needed to be introduced to realize ultra-reliable communications in such a severe radio propagation environment.An architecture of distributed MIMO based RAN was presented.Then,enhanced interference coordination(e IC)was described.Finally,the effectiveness of distributed MIMO based RAN with e IC by computer simulation was showed.

Operational Risk Assessment for Integrated Transmission and Distribution Networks

To satisfy the requirements of accurate operationalrisk assessment of integrated transmission and distribution networks (I-T&D), an integrated operational risk assessment (IORA) algorithm is proposed. Specific cases demonstrate thatan I-ORA is necessary because it provides accurate handlingof the coupling between transmission and distribution networks,accurate analysis of power supply mode (PSM) changes ofimportant users and helps to improve security and stability ofpower grid operations. Two key technical requirements in theI-ORA algorithm are realized, i.e., integrated topology analysisand integrated power flow calculation. Under a certain contingency, integrated topology analysis is used to assess the risksof substation power cuts, network split and PSM changes ofimportant users, while the integrated power flow calculation,based on the self-adaptive Levenburg-Marquard method andNewton method, can be implemented to assess risks of heavyload/overload and voltage deviation. In addition, the graphicsprocessing unit is used to parallelly process some computationintensive steps. Numerical experiments show that the proposedI-ORA algorithm can realize accurate assessment for the entireI-T&D. In addition, the efficiency and convergence are satisfying,indicating the proposed I-ORA algorithm can significantly benefitreal practice in the coordination operation of I-T&D in the future.

ANALYSIS OF THE TRANSMISSION PROPERTIES OF TAPERED MUTLICONDUCTOR INTERCONNECTING BUSES IN HIGH-SPEED INTEGRATED CIRCUITS

Analysis approach and formulas for the transmission properties of uniform multicon-ductor interconnecting buses in high-speed integrated circuits are presented in this article. And further, by using a network approach, a tapered bus system can be analyzed as a set of cascaded uniform buses with slightly different strip widths. Obtained results are in good agreement with the experimental data.

Sensitivity analysis of distributed parameter elements in high-speed circuit networks

This paper presents an analysis method, based on MacCormack＇s technique, for the evaluation of the time domain sensitivity of distributed parameter elements in high-speed circuit networks. Sensitivities can be calculated from electrical and physical parameters of the distributed parameter elements. The proposed method is a direct numerical method of time-space discretization and does not require complicated mathematical deductive process. Therefore, it is very convenient to program this method. It can be applied to sensitivity analysis of general transmission lines in linear or nonlinear circuit networks. The proposed method is second-order-accurate. Numerical experiment is presented to demonstrate its accuracy and efficiency.

Joint Optimization Strategy for Video Transmission over Distributed Cognitive Radio Networks

A novel joint optimization strategy for the secondary user( SU) was proposed to consider the short-term and long-term video transmissions over distributed cognitive radio networks( DCRNs).Since the long-term video transmission consisted of a series of shortterm transmissions, the optimization problem in the video transmission was a composite optimization process. Firstly,considering some factors like primary user's( PU's) collision limitations,non-synchronization between SU and PU,and SU's limited buffer size, the short-term optimization problem was formulated as a mixed integer non-linear program( MINLP) to minimize the block probability of video packets. Secondly,combining the minimum packet block probability obtained in shortterm optimization and SU's constraint on hardware complexity,the partially observable Markov decision process( POMDP) framework was proposed to learn PU's statistic information over DCRNs.Moreover,based on the proposed framework,joint optimization strategy was designed to obtain the minimum packet loss rate in long-term video transmission. Numerical simulation results were provided to demonstrate validity of our strategies.

Vertical Integration by Means of Profinet

This paper discusses some aspects of interdisciplinary problems of industrial automation curriculum in Virumaa College of Tallinn University of Technology at engineering level. The problems being faced by engineers are increasingly interdisciplinary and complicated because the development of new products and processes depends upon the integration of many different technologies. Expansion of possibilities of already existing fieldbus systems is carried out by means of integration them into Profinet （PROcess Field NET） communications. The lab set-model of vertical integration-for data gathering from smart Profibus PA sensor, data transmission, controllers configuration for Profinet IO direct interfacing of distributed field devices on the Ethernet is discussed in this paper.

多园区综合能源系统接入主动配电网双层优化调度研究

随着园区综合能源系统的不断发展与普及,其与上级大电网并网实现交互已成为大势所趋。文中构建了通过联络线相耦合的多园区综合能源系统接入主动配电网的双层优化调度模型。在主动配电网层面,以最小运行成本为目标,充分考虑了联络线功率、分布式电源、储能设备、柔性负荷、电动汽车等可调度资源;在园区层面,以多园区总运行成本最小为目标,考虑了相互联结的多类型园区的并网情况。利用目标级联法对双层模型进行求解。通过算例验证,文中所构建模型具有良好的经济特性与削峰填谷效果,充分证明了文中所提模型的经济性与有效性。

面向区域自治的配电网动态区域划分方法

具有间隙性及波动性特征的大量分布式光伏接入配电网,为配电网的源荷功率平衡及节点电压调节等带来了新的技术挑战。为充分利用配电网中多类型调节资源的调节能力,提高新能源高比例接入下配电网的自治能力,提出了一种面向区域自治的配电网动态区域划分方法。首先,结合分布式光伏和负荷预测数据,衡量配电网中多类型可调资源的调节能力,建立考虑模块度、电压调节能力和功率持续调节能力的综合指标体系。其次,采用遗传算法求解各区域最优综合指标,结合运行状态及调控需求设计分区结构更新触发机制,更新分区结果。最后,结合实际配电网典型日运行数据的仿真算例及对比分析验证了所提区域动态划分方法在提高区域电压调节能力和功率持续调节能力方面的优势,并分析了不同指标权重,不同触发阈值以及不同时间尺度对分区结果的影响。

基于电网线路传输安全的电力市场分布式交易模型研究

电力市场分布式交易模型可有效缓解传统集中模型下市场主体的隐私安全等问题,但难以在保障市场主体收益和电力系统安全稳定运行的同时,实现社会福利最大化.因此,基于电网线路传输安全,首先以社会福利最大化为目标,构建集中式交易模型,并采用拉格朗日乘子法和对偶定理,将其等价分解为各市场主体自身利益最大化的分布式交易模型.在此基础上,设计2种适用于不同情形的分布式交易方法及其求解算法,并构造电网安全成本影响市场主体的决策,从而保证电网线路传输安全.最后,基于算例分析,验证了2种交易方法的有效性.

面向高比例分布式能源接入的输配网两阶段风险调度研究

随着大量高比例可再生能源接入配电网,潮流呈现双向化,输电网和配电网互联性增加,分散独立的调度影响电网可靠稳定运行水平。面对输网与配网间互济需求增强的现状,提出了面向高比例分布式能源接入的输配电网两阶段风险调度研究。首先以最小运行成本为目标,构建考虑输配电网不同运行风险的日前经济调度模型,在风险限值约束情况下协同优化系统源网荷储多种可调资源;其次构建目标函数为综合风险值最小的日内风险调度模型,计算三类运行风险指标值,对日前可调控资源进行出力计划调整;最后通过改进的粒子群算例求解模型,证明了该模型可使输配电网间交互协调,协同优化运行成本与运行风险,验证了所提两阶段风险调度模型的有效性和优越性。

基于D2D通信和虚拟MIMO的飞行器集群网络传输方案设计

在无中心飞行器集群网络中,非直通条件节点间不同的中继路径可能导致较大路径损耗落差,为有限资源前提下网络传输能力的提升带来困难。参考5G移动通信中的终端直通(Device to Device,D2D)技术与中继通信中的虚拟多输入多输出(Multiple-Input Multiple-Output,MIMO)技术,提出一套D2D通信与虚拟MIMO技术结合的无中心飞行器集群网络传输方案。重点研究在正交资源模式下,将不同的协作传输协议与空时编码进行组合,在信噪比、误比特率、接入概率等方面对通信性能的影响。仿真结果表明:D2D通信与虚拟MIMO技术结合的传输方案在不增加资源的前提下,对集群网络的通信性能有明显提升,且引入分布式空时编码可进一步优化误比特率性能,但3种传输协议在不同传输质量评价方向的改善有所不同。

基于喷泉码信息差异分簇的V2V协作数据分发方案

新兴车联网应用需要分发的数据量不断增加,车辆难以在一个RSU通信范围内收到完整数据,跨RSU通信完成率低,时效性差。针对此问题,提出一种基于喷泉码信息差异分簇的V2V协作数据分发方案。经过喷泉编码的数据由RSU广播;车辆通过XGBoots预测车速,以此计算V2V链路生存时间;链路可靠性和车辆的喷泉码信息差异构建引力模型来分簇,在簇内以V2V传输共享编码包,在保证完成率的前提下大幅降低数据分发延迟。仿真结果表明,与已有方案ECDS相比,对于不同大小的数据,该方案在保证完成率的基础上,平均时延降低了38%。

高比例分布式可再生能源交直流混合配电网运行调控:科学问题与技术框架

随着分布式可再生能源发电与中低压直流组网技术的快速发展,未来配电网必然向复杂的交直流混合形态演进,其运行调控技术面临许多新的挑战。在高比例分布式可再生能源交直流混合配电网(HR-HDN)运行调控技术发展需求分析的基础上,提炼出HR-HDN运行调控技术的3个科学问题,并以多类型可控设备协同、源-网-荷-储高度互动化和市场化需求为研究主线,从稳定控制、故障主动防御与恢复、电力市场机制辅助调控以及“平台+数据”数字化集成调控4个方面,提出了HR-HDN的运行调控技术框架。最后,对HR-HDN运行调控关键技术的未来发展进行了展望。

考虑需求响应和共享储能的微网联盟两阶段优化调度

随着共享储能的推广,能源信息的流动与共享得到进一步发展,为促进能源管理和提升利用效率,提出一种基于共享储能和需求响应的微网联盟两阶段优化调度策略。首先,建立多微网联盟-共享储能系统运行框架,并基于综合贡献度对微网利益分配过程进行建模;其次,建立两阶段优化调度模型,第一阶段以多微网联盟-共享储能系统净收益最大为目标,第二阶段考虑用户的需求响应,求解耗能用户的最低购能费用;再次,利用求解器对两阶段模型分别进行求解,得到多微网系统的分时能源价格、各微网设备的运行状态、需求响应后负荷和各微网利益;最后,设置4个方案作为算例,验证所提优化策略在提高各微网收益和激励用户需求响应的有效性。

考虑不确定性的配电网-多综合能源系统分布式协同规划

综合能源系统的多点并网加剧了配电网规划的“维数灾害”,提出兼顾多主体利益均衡性和分析计算高效性的配电网-多综合能源系统的分布式协同规划方法。以区间数刻画系统内的源-荷不确定性,构建计及多利益主体的配电网-多综合能源系统分布式协同规划框架;考虑多源联供的低碳清洁性、综合能源系统对配电网的支撑性和多能互补性,建立考虑奖惩碳交易机制的配电网-多综合能源系统双层规划模型;采用基于最大变差分析的目标级联分析法求解含有区间不确定性和多主体耦合性的规划模型。仿真结果表明,所提方法有效降低了配电网耦合综合能源系统的复杂度,提升了系统内各利益主体的均衡性。

基于增量配电网园区的源网荷储一体化平台建设方案研究与应用

为满足增量配电网园区对供电能力、电能质量的较高要求,落实可再生能源消纳能力,提出了一种增量配电网园区源网荷储一体化平台建设方案,对一体化平台建设的思路及架构展开研究,并通过新疆甘泉堡源网荷储一体化控制系统建设实例说明设计可行性。通过建设“源网荷储一体化、发配售电一条龙”的综合智慧平台,融合分布式光伏、风电、储能、换电/充换电站,实现增量配电网资源合理配置和绿色低碳能源高比例发展,充分发挥“源网荷储”灵活调节作用和实现能源互联网智能化应用,提高园区配电网供电的高稳定性和高可靠性,促进配电网建设,提高配电网运营效率,降低园区企业用电成本,从而推动产业转型、助力能源互联网建设和促进绿色低碳智慧能源快速发展。

基于光纤传感的铁路牵引网故障自动识别技术

由于现有的铁路牵引网故障识别方法在识别过程中易受到周围环境影响,故障识别准确率较低,因此,提出基于分布式光纤传感的铁路牵引网故障自动识别方法。构建3种牵引网故障自动识别规则,通过自动识别规则,使用分布式光纤传感对故障特征进行提取;使用变量分析对故障损伤数据进行处理,筛选符合传输的故障损伤数据进行传输,计算故障损伤数据,运用网络拓扑结构对故障特征信息进行传输;通过融合层次的诊断,进行数据的融合,得到诊断结果,实现基于分布式光纤传感的铁路牵引网故障自动识别。