Power management in co-phase traction power supply system with super capacitor energy storage for electrified railways

Increasing railway traffic and energy utilization issues prompt electrified railway systems to be more economical,efficient and sustainable.As regenerative braking energy in railway systems has huge potential for optimized utilization,a lot of research has been focusing on how to use the energy efficiently and gain sustainable benefits.The energy storage system is an alternative because it not only deals with regenerative braking energy but also smooths drastic fluctuation of load power profile and optimizes energy management.In this work,we propose a co-phase traction power supply system with super capacitor(CSS_SC)for the purpose of realizing the function of energy management and power quality management in electrified railways.Besides,the coordinated control strategy is presented to match four working modes,including traction,regenerative braking,peak shaving and valley filling.A corresponding simulation model is built in MATLAB/Simulink to verify the feasibility of the proposed system under dynamic working conditions.The results demonstrate that CSS_SC is flexible to deal with four different working conditions and can realize energy saving within the allowable voltage unbalance of 0.008%in simulation in contrast to 1.3%of the standard limit.With such a control strategy,the performance of super capacitor is controlled to comply with efficiency and safety constraints.Finally,a case study demonstrates the improvement in power fluctuation with the valley-to-peak ratio reduced by 20.3%and the daily load factor increased by 17.9%.

New generation traction power supply system and its key technologies for electrified railways

Unlike the traditional traction power supply system which enables the electrified railway traction sub- station to be connected to power grid in a way of phase rotation, a new generation traction power supply system without phase splits is proposed in this paper. Three key techniques used in this system have been discussed. First, a combined co-phase traction power supply system is applied at traction substations for compensating negative sequence current and eliminating phase splits at exits of substations; design method and procedure for this system are presented. Second, a new bilateral traction power supply technology is proposed to eliminate the phase split at section post and reduce the influence of equalizing current on the power grid. Meanwhile, power factor should be adjusted to ensure a proper voltage level of the traction network. Third, a seg- mental power supply technology of traction network is used to divide the power supply arms into several segments, and the synchronous measurement and control technology is applied to diagnose faults and their locations quickly and accurately. Thus, the fault impact can be limited to a min- imum degree. In addition, the economy and reliability of the new generation traction power supply system are analyzed.

FPGA-based Digital Implementation of Flexible Power Control for Three-phase to Single-phase MMC-based Advanced Co-phase Traction Power Supply System

A three-phase to single-phase modular multilevel converter based advanced co-phase traction power supply(MMC-ACTPS) system is an effective structure to address the concerns of phase splitting and poor power quality of the conventional electrified railway. Due to the large number of MMCACTPS system modules, I/O resources and computing speed have high requirements on processors. Moreover, the module capacitor balance is challenging because the sorting time is too long when the traditional sorting algorithm for voltage balance is used. To solve the above issues, a digital implementation scheme of flexible power control strategy for three-phase to single-phase MMC-ACTPS system based on field programmable gate array(FPGA), which has sufficient I/O resources, has been proposed. Due to the parallel execution characteristics of the FPGA, the execution time of the controller and the modulator can be greatly reduced compared with a digital signal processor(DSP) + FPGA or DSpace. In addition, an improved sorting algorithm is proposed to reduce the sorting time and the implementation steps are analyzed. Finally, simulation and experimental results are presented to demonstrate the effectiveness and correctness of the proposed control strategy.

分布式储能在成都科幻馆的应用

通过电化学储能在2023年第81届世界科幻大会主场馆——成都科幻馆项目的示范应用,重点从应用场景、并网接入电压、接入系统方案、运行策略等方面分析用户侧分布式储能在民用建筑的应用要点。

考虑供电能力提升的低压配电网柔性互联规划

构建具有可靠供电能力的低压配电网具有重要意义,然而低压配电网供电能力受到低压配电变压器负载、低压配电网新能源消纳能力以及低压配电网供电电压3大要素影响。因此,该文基于低压配电网柔性互联技术提出考虑供电能力提升的低压配电网柔性互联规划方法,通过抽取影响低压配电网供电能力的主要场景建立低压配电网柔性互联规划框架。另外,针对该文多主体规划运行模型的不确定性,采用信息间隙决策理论(information gap decision theory,IGDT)与基于Wasserstein距离的分布鲁棒方法进行精细化建模。最后,采用MATLAB和CPLEX求解器在IEEE 38节点配电网上进行算例分析。仿真结果表明,该规划方法在有效提升低压配电网供电能力的同时具有更好的经济性。

考虑转供与重构协同的多端柔性互联配电网供电恢复策略

柔性互联装置(FID)实现配电网不同馈线之间的柔性互联,可实现故障后配电网的快速恢复供电。该文以含直流网络的四端柔性互联配电网为研究对象,提出基于FID和网络重构的多端柔性互联配电网两阶段供电恢复策略。首先,在分析FID运行模式工作原理的基础上,提出了故障快速转供的FID平滑控制结构和考虑开关同期并网控制虚拟同步发电机(VSG)控制策略,支撑故障后第一阶段FID的快速供电恢复;然后,通过建立和求解考虑联络开关和FID容量限制的全局优化模型得出FID与网络重构相结合的第二阶段供电恢复策略,更大限度地恢复失电负荷;最后,利用PSCAD/MTDC仿真软件搭建了一个58节点四端含直流网络的柔性配电系统进行仿真验证。结果表明,所述供电恢复策略不仅能实现部分负荷的不停电转供,还能够通过网络重构大幅提高负荷恢复水平。

欧洲大范围跨国电力互联在极端天气下电力安全保供中的作用分析

随着全球气候变化不断加剧,极端天气对电力系统的影响日益增强,电网在电力安全保供中发挥的作用愈发受到关注。欧洲电网作为世界上规模最大的跨国互联电网,其在极端天气下的电力安全保供中发挥的作用值得研究借鉴。首先,对欧洲电网跨国互联进程、跨国电力配置、跨国互联目的进行梳理,并从电力交易与调度的关系、跨国电网耦合机制、跨国输电通道容量分配机制等角度分析欧洲跨国电网的交易与调度特征。其次,以2022年夏季极端高温干旱天气下的欧洲电力供应紧张事件为例,从电量余缺互济、平衡资源共享、统一电力市场支撑、可再生能源消纳等方面分析欧洲跨国互联电网在电力安全保供中发挥的“四个平台”作用。然后,对欧洲跨国互联电网面临的问题进行剖析。最后,提出对中国电网发展的思考及建议。

基于直流线路互联的区-隧供电系统弹性恢复策略

在“双碳”目标下,以服务区光伏车棚、光伏隧道为代表的能源交通融合供电场景逐步普及,这使得形态开放且布局分散的区-隧供电系统在面临极端灾害或人为攻击时更为脆弱。为此,该文提出一种基于直流线路互联的区-隧供电系统弹性恢复策略。根据灾害前对直流线路的改造与韧性加固计划,首先,提出了基于直流线路被优先遍历的可行拓扑搜索策略,用于保障所提系统在极端灾害后的有效互联;其次,基于对故障负荷重要级权重的多层级分类策略,该文先后以重要负荷恢复量最大化和系统额外损耗最小化为目标构建了故障恢复目标函数,共同保证极端灾害发生后系统基于稀缺分布式能源的最大弹性恢复;再次,基于传统二阶锥松弛方法可能挣脱原始约束的缺陷,提出通过约束额外损耗中流经电流分量实现对混合整数二阶锥规划问题的收敛,确保所提模型在不同初始条件下的稳定适用;最后,通过涵盖区-隧供电系统的改进IEEE 123节点配电网进行仿真,验证了所提策略的有效性。

Multi-timescale optimization scheduling of interconnected data centers based on model predictive control

With the promotion of“dual carbon”strategy,data center(DC)access to high-penetration renewable energy sources(RESs)has become a trend in the industry.However,the uncertainty of RES poses challenges to the safe and stable operation of DCs and power grids.In this paper,a multi-timescale optimal scheduling model is established for interconnected data centers(IDCs)based on model predictive control(MPC),including day-ahead optimization,intraday rolling optimization,and intraday real-time correction.The day-ahead optimization stage aims at the lowest operating cost,the rolling optimization stage aims at the lowest intraday economic cost,and the real-time correction aims at the lowest power fluctuation,eliminating the impact of prediction errors through coordinated multi-timescale optimization.The simulation results show that the economic loss is reduced by 19.6%,and the power fluctuation is decreased by 15.23%.

柔性互联技术在配电网中的应用研究

为实现清洁能源就近消纳及源荷储潮流动态平衡,提升配电网供电可靠性,提出了一种供电分区间柔性互联技术方案。该方案在配电网络中嵌入柔性互联装置,不同供电分区间通过直流方式柔性连接,实现两个不同电源的功率互济、故障快速转供,以及分布式电源高效消纳、源荷储多元聚合高效运行;对配电网柔性互联系统的功能和典型架构进行了阐述,并对关键设备、运行模式、控制模式切换进行了介绍,为配电网区域互联和升级转型提供参考。

基于PoE供电的楼宇智能互联照明系统设计

随着物联网技术的发展,智能照明系统已成为建筑能源管理的重要组成部分。文章以Po E供电的楼宇智能互联照明系统为研究对象,探讨其设计方案。首先介绍了Po E技术原理及其在照明系统中的应用,然后详细阐述了系统架构、硬件设计和软件设计。在硬件设计中,考虑了照明系统的功率需求,采用了高效的LED灯具和节能型电源。在软件设计中,结合人体感知、环境变化和光源特性等因素,设计了智能照明控制算法。最后,对系统进行了仿真和实验验证,结果表明该系统具有良好的能效和稳定性,具备实际应用价值。

采用潮流控制器的贯通型牵引供电系统负序治理模型及控制策略

针对树形双边贯通牵引供电系统负序导致的电力系统侧公共连接点处三相电压不平衡问题,提出在树形双边贯通牵引供电系统中加装由降压变压器、潮流控制器(PFC)和控制器组成的补偿装置进行功率转移的负序补偿方案;在建立采用PFC的贯通型牵引供电系统拓扑结构和数学模型的基础上,设计合理的约束参数和控制策略,通过控制补偿装置改变电力系统侧功率分布,从而实现负序补偿;采用MATLAB/Simulink仿真试验平台,分析补偿装置所需容量随负序补偿程度的变化规律,并计算最小化负序补偿容量,对补偿方案进行验证。结果表明:基于功率转移的负序补偿方案能够灵活调节公共连接点处负序功率和无功功率含量;可将公共连接点处三相电压不平衡度的最大值降低至4%,95%统计值降低至2%,满足了国家标准,从而验证了基于功率转移负序补偿方案的有效性。

新型铁路电源净化装置的典型应用

铁路电力系统是电力系统网络的重要组成部分,正在向着智能电网的方向发展。文章以铁路电力系统的构成为基础,阐述了铁路牵引电力系统和铁路电力供配电系统高效互联装备的应用需求与工程应用情况,介绍了一种铁路净化电源装置,分析了其目前面临的挑战和工程测试情况。结果表明,该装置在铁路电力系统中有较高的实用性。

Overview of Resilient Traction Power Supply Systems in Railways with Interconnected Microgrid

In recent years,the achievement of a renewable and sustainable traction power supply system(TPSS)in the rail sector has become a significant challenge.Focusing on this issue,this paper firstly provides a comprehensive overview and classification of the state-of-art TPSSs in DC and AC railway.Then,together with low voltage(LV)DC,medium voltage(MV)DC,LV AC,and hybrid AC/DC interconnected microgrid(IMGs),various architectures of resilient TPSSs are proposed for renewable energy integration into DC and AC railway.The resilient TPSS offers on-site access and local consumption of renewable sources alongside railways and guarantees a sustainable power supply in the case of grid disturbances and failures,e.g.,voltage unbalance,harmonic and violent fluctuation,power outage,and extreme events in the wake of natural disasters and extreme weather.This approach also helps facilitate the development of the next generation TPSSs for enhanced flexibility and sustainability.Then,based on a comparative analysis of different resilient TPSSs,a brief outlook of the future trend is given.Finally,it is concluded that resilient TPSS provides a universal solution for both renewable energy integration and high-quality power supply against grid disturbances and failures.

Carbon neutrality policy and interconnection scenario according to the perspective of Republic of Korea

The future energy policy,long-term energy supply plan,and necessity of power system interconnection are discussed considering the climate change agreement and national carbon neutrality policy.Although several studies have been conducted on power system interconnection related projects,a few reviews have been performed related to the Greenhouse Gas Convention in North-East Asian(NEA)regions.Therefore,the future directions and possible scenarios on power system interconnection are studied by combining the issues by comprehensively considering carbon neutrality policy according to the perspective of Korea.

基于高功率脉冲技术的微深孔溅射关键工艺研究

根据高功率脉冲电源在溅射时能提升离化率,增加离子浓度的特点,研究了高功率脉冲电源的峰值电流、频率、脉宽与离化效果之间的关系,并比对了溅射效果,分析了高功率脉冲与偏压电源之间的作用关系。通过这些关键工艺的研究,成功实现了深径比10∶1的微孔溅射金属化并进行工程应用,为三维集成高深径比微孔金属化提供了一种低成本的解决方案。

计及动态电压稳定约束的分区柔性互联电网最大供电能力计算

最大供电能力计算是分区柔性互联电网规划的重要问题,随着可再生能源大量接入电网,动态电压失稳问题愈发突出。计及动态电压稳定约束的最大供电能力计算模型非线性特征明显,给模型求解带来较大挑战。首先,运用改进的小干扰分析法对动态电压稳定进行分析,建立计及动态电压稳定性指标的最大供电能力的数学模型。其次,给出基于深度确定性策略梯度算法的最大供电能力计算方法框架,设计其动作与状态空间、奖励函数、神经网络与学习流程。最后,以某电网为例进行验证,该方法在有效避免电网动态电压失稳的同时优化分区互联电网的最大供电能力计算。

树形双边贯通供电系统运行策略及对外部电源的负序影响

树形双边贯通供电系统能够实现长距离无分相贯通供电,提高系统的再生制动能量直接利用率。当树形双边贯通供电方案仅由单相接线变压器构成时,列车在公共连接点处产生的三相电压不平衡度将加剧,一旦负序超标,将面临负序带来的不利影响。为了确保系统的良好运行,避免负序带来的不利影响,有必要评估系统的负序情况。分别研究采用单相接线变压器和采用组合式同相供电装置构成的树形双边贯通供电系统及其运行策略,针对采用组合式同相供电装置的方式提出同相供电装置的就地控制策略。以公共连接点处三相电压不平衡度作为评估树形双边贯通供电系统对外部电源的负序影响的评估指标,分别构建传统Vv接线变压器的单边供电系统、采用单相接线变压器构成的树形双边供电系统和采用组合式同相供电装置构成的树形双边供电系统的负序评估模型。以某线路为例,基于构建的负序评估模型对采用树形双边贯通供电方案后的系统的三相电压不平衡度进行评估,并与既有供电方案的结果进行对比,采用单相组合式同相供电的树形双边供电改造方案后,三相电压不平衡度最大值为1.65%,95%概率大值为1.20%,均符合国家标准。结果表明采用树形双边贯通供电系统方案负序问题得到了极大的改善,符合国家标准的要求,也证明了本文同相供电装置运行策略的有效性。

电源电压矢量快速定位的AC/DC变换器选择性控制

为了提高交直流配电网中柔性互联装置的控制精度和扰动抑制能力,避免冗余计算问题,提出了一种基于电源电压合成矢量快速定位的AC/DC变换器功率选择性控制方法。采用一种并行处理的逻辑计算方法获得电源电压矢量所在扇区,避免了传统功率控制中的坐标变换和锁相环节,节省了处理器资源;在功率内环制定了开关选择优先级,在固定时间间隔内结合场景需求实现开关状态的实时选择。与传统功率控制策略的仿真和实验对比,进一步验证了所提选择性控制方法在稳态控制精度、扰动抑制以及暂态响应方面的优越性。

含机会约束的柔性互联配电网供电恢复方法

随着分布式电源的接入,其出力的不确定性势必会影响柔性互联配电网的供电恢复。为此建立了供电恢复机会约束模型,使用威布尔分布和贝塔分布模拟风光出力,采用抽样平均近似方法把模型变换成混合整数二次约束规划模型进行求解,并以三端口智能软开关互联三个IEEE 33节点网络为算例进行分析验证。结果表明:随着置信水平降低,恢复负荷比例增加,网络损耗与电压偏差增大。为了平衡电网运行安全性与经济性,应对置信水平保持合理设置。