计及供能可靠性动态约束与碳减排的充能型微电网互联系统优化模型

推动新能源汽车产业规模化发展是实现交通和多能源系统低碳转型的重要途径,为保障系统供能可靠性与碳减排能力的提升,该文构建了计及供能可靠性动态约束与碳减排的充能型微网互联系统优化模型。首先,研究各微电网的运行特性以及微电网间的能量交互特性,建立低碳充能型多能源微网互联系统(MCMIS-LCEs)模型,并在此基础上建立多能源供能与碳减排协调模型;其次,考虑能源转换、存储与充能设备故障对MCMIS-LCEs供能可靠性的动态影响,针对设备故障特点建立多状态可靠性动态量化评估模型;然后,在互联系统供能可靠性约束、运行约束等条件下,建立考虑碳减排、充能时间与供能成本协同的MCMIS-LCEs多目标优化模型;最后,基于充能站实际能源与车流量数据进行算例的仿真验证。结果表明,该文提出的MCMIS-LCEs及其优化模型能够实现多能源转换、存储与充能设备间的高效协调,提升整体互联系统的经济性、碳减排能力、垃圾处理能力、电网调节能力,以及充能供能可靠性。

大电网互联系统的频率与潮流问题

大电网互联以后 ,系统频率将更加平稳 ,一般的负荷波动所产生的频率很小。但是很小的频率变化可能使联络线潮流产生很大的变化。无频移的潮流调整法适用于网间联络线潮流的调整 ,可以达到调整特定线路的潮流而不影响其他联络线潮流的目的。互联大电网应严格控制并网前的频差。当互联电网中的任一电网的负荷约为 2 0 0 0 0 MW时 ,建议并网前的频差控制在 0 .0 5 Hz以下。

基于ADMM-GBS考虑故障影响的互联微电网多时间尺度优化调度

极端事件攻击微电网可能造成负荷电能供应不足导致大停电事故。针对互联微电网系统,提出了一种考虑极端事件的分布式多时间尺度故障优化调度策略。在故障条件下以系统用户侧削减负荷量最小为目标,建立了互联微电网系统日前-日内两阶段滚动调度模型;基于鲁棒思想,考虑极端事件的时空特性以及故障线路的不确定性,采用分层随机抽样形成故障集,将其作为初始数据确定系统最恶劣故障场景;针对该场景进行线路加固后,采取高斯回代交替方向乘子法(ADMM-GBS)得到最优故障调度策略。通过算例分析验证了所提模型和调度策略的有效性。

基于交替方向乘子法的互联微电网系统分布式优化调度

孤立微电网之间的互联问题得到了广泛关注,优化调度是保证互联微电网系统运行经济性的重要环节。文章提出一种基于交替方向乘子法(alternating direction method of multipliers,ADMM)的互联微电网系统分布式优化调度方法。首先,对互联微电网系统优化调度的基本模型进行了说明;其次,介绍了各分布式电源的基本模型,建立面向实时优化调度的储能系统成本模型,将储能系统寿命损耗成本与放电功率之间的关系等效为二次型函数;然后,提出了基于ADMM的分布式优化调度模型及求解算法,在保证各微电网隐私的情况下,仅需提供"期望交换功率",即可通过交互迭代实现互联系统的最优调度。最后,通过三微电网互联算例,分析了分布式优化调度的运行结果,验证了所提方法的有效性。

互联系统可靠性效益评估方法

提出了 2电力系统互联的可靠性效益评估模型和算法。该模型充分考虑了互联系统负荷的错峰及同时率问题 ,联络线容量及其可用率问题 ,各系统的容量及能量约束问题等因素。其中互联系统负荷的错峰及同时率问题通过按小时计算来精确模拟 ,联络线容量及其可用率问题通过串联系统的可靠性计算来衡量 ,各系统的容量及电量约束通过随机生产模拟来确定。利用所提模型及算法对实际互联系统进行了计算 ,详细分析了联网效益 。

拒绝服务攻击下互联多区域电网系统的弹性负载频率控制

为实现互联多区域电网系统的频率稳定,负荷频率控制需要通过开放通信网络获取信号和发送命令。在开放的通信网络环境下,系统不免会受到天气、网络攻击等外界环境的干扰,引起电网频率波动。例如拒绝服务(denial-of-service, DoS)攻击,这些因素会阻止一定数量的信号传输,从而降低负载频率控制方案的性能,甚至导致电网系统不稳定。针对测量通道和控制通道拒绝服务攻击下互联多区域电网系统,完成弹性负载频率控制。首先给出DoS攻击频率和持续时间满足的假设条件,然后设计灵活的弹性控制器,保证闭环系统的输入状态稳定性,并确定合适的采样机制,实现系统性能和通信资源的有效折衷平衡。最后,以两区域互联电网系统为对象进行仿真,得到所提方法能够有效地克服DoS攻击和扰动带来的影响,保证了闭环系统的输入状态稳定性,验证了此方法的有效性。

Application of Component Technology to E-commerce System

At present E-commerce system tends to become more complex, and traditional system designing methods can not fufil the need of E-commerce system, thus requiring an effective methodas solution. With this concern, this paper introduces some concepts of component technology, then brings forward the new connotation and basic features of component technology through the analysis of its technological character. This paper finally discusses the application of component technology to E-commerce system.

Smart Grid Cyber Security： An Overview of Threats and Countermeasures

The smart grid is the next generation of power and distribution systems. The integration of advanced network, communications, and computing techniques allows for the enhancement of efficiency and reliability. The smart grid interconnects the flow of information via the power line, intelligent metering, renewable and distributed energy systems, and a monitoring and controlling infrastructure. For all the advantages that these components come with, they remain at risk to a spectrum of physical and digital attacks. This paper will focus on digital vulnerabilities within the smart grid and how they may be exploited to form full fledged attacks on the system. A number of countermeasures and solutions from the literature will also be reported, to give an overview of the options for dealing with such problems. This paper serves as a triggering point for future research into smart grid cyber security.

Effectiveness of Optimal Arrangement of the Residences Operated by Reactive Power Control for a Clustered Grid-Interconnected PV System

There is a danger of power generation efficiency decreasing due to voltage increase when clustered residential PV systems are grid-interconnected to a single distribution line. As a countermeasure, installation of the reactive power control of an inverter at each residence has been considered. However, there are not many types of inverters that can operate reactive power control because there are insufficient effects on a low voltage distribution line with low penetration PV with reactive power control. Therefore, it is necessary to consider how to increase generation efficiency with a lower number of inverters. In this paper, four Japanese standard distribution line structures, for example of a residential area on ＂C1＂, where 2,160 residential PV systems are grid-interconnected, are selected. The optimal setting of reactive power control at each residence is computed on the distribution lines with a greedy method.

Advanced Reactive Power Control at Individual Residences to Smooth Energy Loss Fluctuation for a Clustered Grid-Interconnected PV System

Reactive power control can control voltage within the proper range from the power network side or from the distribution generation （PV （photovoltaic）） side. Reactive power control from the power network side is simpler because little controlled object apparatus, such as STATCOM, is required. However, it is difficult to optimize the individual voltages of residential consumers because few data have been obtained by the power network side as compared with the power generation side. Energy loss at each residence with PV is different due to the difference in the grid-interconnection condition, such as distribution line impedance when the same operating voltage is set at all residences. Therefore, in this paper, the authors propose an advanced reactive power control method for residential PV systems in order to optimally control the voltage at individual residences so as to minimize energy loss fluctuation. The effectiveness of the proposed reactive power control is demonstrated by numerical simulation.