The paper dwells on the unified power quality indexes characterizing the phenomenon of voltage unbalance in three-phase systems. Voltage unbalance is one of the commonest occurrences in the town mains of 0.38 kV volta...The paper dwells on the unified power quality indexes characterizing the phenomenon of voltage unbalance in three-phase systems. Voltage unbalance is one of the commonest occurrences in the town mains of 0.38 kV voltage. The phenomenon describes as inequality of vector magnitude of phase voltage and shearing angle between them. Causes and consequences of the voltage unbalance in distribution networks have been considered. The algorithm, which allows switching one-phase load, has been developed as one of the methods of reducing the unbalance level. The algorithm is written in the function block diagram programming language. For determining the duration and magnitude of the unbalance level it is proposed to introduce the forecasting algorithm. The necessary data for forecasting are accumulated in the course of the algorithm based on the Function Block Diagram. The algorithm example is given for transforming substation of the urban electrical power supply system. The results of the economic efficiency assessment of the algorithm implementation are shown in conclusion. The use of automatic switching of the one-phase load for explored substation allows reducing energy losses (active electric energy by 7.63%;reactive energy by 8.37%). It also allows improving supply quality to a consumer. For explored substation the average zero-sequence unbalance factor has dropped from 3.59% to 2.13%, and the negative-sequence unbalance factor has dropped from 0.61% to 0.36%.展开更多
分布式能源的广泛发展使其成为电力市场的考虑重点,而传统的数据交互平台无法满足大规模分布式能源交易高效灵活、安全可靠的需求。为解决高信息处理复杂度与安全快速交易需求之间的矛盾,文中提出基于云边协同和区块链的分布式能源交易...分布式能源的广泛发展使其成为电力市场的考虑重点,而传统的数据交互平台无法满足大规模分布式能源交易高效灵活、安全可靠的需求。为解决高信息处理复杂度与安全快速交易需求之间的矛盾,文中提出基于云边协同和区块链的分布式能源交易系统架构和整体设计方案。首先设计了云计算与边缘计算协同并结合两层区块链的系统架构,利用区块链技术实现交易去中心化,提高了交易的自主高效性,利用云边协同提升海量数据的处理能力和交易系统的扩展能力。然后基于双向竞价和预测补偿设计了分布式能源的交易机制,进一步对区块链的核心共识算法进行分析,并采用改进委托权益证明(delegated proof of stake,DPoS)作为交易系统的高效率、高可靠共识算法,实现大规模分布式能源的高效可靠交易,促进分布式能源参与电网调节,提高电网稳定运行水平。最后通过应用实例验证了所提系统对大规模分布式能源交易的适应性和优越性。展开更多
利用希尔伯特(Hilbert)变换能够得到电力系统振荡中电流信号包络线的特点,根据系统正常运行、纯振荡以及振荡中再故障情况下包络线的不同变化趋势,采用两相电流包络线之差的突变量作为判别量,提出了一种新型的振荡中再故障判别元件,该...利用希尔伯特(Hilbert)变换能够得到电力系统振荡中电流信号包络线的特点,根据系统正常运行、纯振荡以及振荡中再故障情况下包络线的不同变化趋势,采用两相电流包络线之差的突变量作为判别量,提出了一种新型的振荡中再故障判别元件,该判别元件的计算精度不受电力系统振荡时频率变化的影响。大量 ATP 仿真证明了该元件在纯振荡过程中能够可靠不误动,并且可以快速有效地识别系统振荡中发生的各种故障。而且,文中采用的算法实现方便,计算量小,具有在工程中良好的实际应用价值。展开更多
基于实时数字仿真器(real time digital simulator,RTDS)搭建了仿真模型,并将RTDS与实际直流输电控制及保护装置连接,建立了交直流混合系统实时仿真实验平台。在此基础上,针对"1.15"高肇直流极2闭锁事故进行了仿真研究,成功...基于实时数字仿真器(real time digital simulator,RTDS)搭建了仿真模型,并将RTDS与实际直流输电控制及保护装置连接,建立了交直流混合系统实时仿真实验平台。在此基础上,针对"1.15"高肇直流极2闭锁事故进行了仿真研究,成功地再现了实际故障过程,并分析了事故发生的真正原因:直流极控装置误将瞬时故障检测为永久故障,终止直流线路重启;并提出了合理的改进措施:修改极控装置中接地检测故障装置和直流线路重启去游离时间。展开更多
文摘The paper dwells on the unified power quality indexes characterizing the phenomenon of voltage unbalance in three-phase systems. Voltage unbalance is one of the commonest occurrences in the town mains of 0.38 kV voltage. The phenomenon describes as inequality of vector magnitude of phase voltage and shearing angle between them. Causes and consequences of the voltage unbalance in distribution networks have been considered. The algorithm, which allows switching one-phase load, has been developed as one of the methods of reducing the unbalance level. The algorithm is written in the function block diagram programming language. For determining the duration and magnitude of the unbalance level it is proposed to introduce the forecasting algorithm. The necessary data for forecasting are accumulated in the course of the algorithm based on the Function Block Diagram. The algorithm example is given for transforming substation of the urban electrical power supply system. The results of the economic efficiency assessment of the algorithm implementation are shown in conclusion. The use of automatic switching of the one-phase load for explored substation allows reducing energy losses (active electric energy by 7.63%;reactive energy by 8.37%). It also allows improving supply quality to a consumer. For explored substation the average zero-sequence unbalance factor has dropped from 3.59% to 2.13%, and the negative-sequence unbalance factor has dropped from 0.61% to 0.36%.
文摘分布式能源的广泛发展使其成为电力市场的考虑重点,而传统的数据交互平台无法满足大规模分布式能源交易高效灵活、安全可靠的需求。为解决高信息处理复杂度与安全快速交易需求之间的矛盾,文中提出基于云边协同和区块链的分布式能源交易系统架构和整体设计方案。首先设计了云计算与边缘计算协同并结合两层区块链的系统架构,利用区块链技术实现交易去中心化,提高了交易的自主高效性,利用云边协同提升海量数据的处理能力和交易系统的扩展能力。然后基于双向竞价和预测补偿设计了分布式能源的交易机制,进一步对区块链的核心共识算法进行分析,并采用改进委托权益证明(delegated proof of stake,DPoS)作为交易系统的高效率、高可靠共识算法,实现大规模分布式能源的高效可靠交易,促进分布式能源参与电网调节,提高电网稳定运行水平。最后通过应用实例验证了所提系统对大规模分布式能源交易的适应性和优越性。
文摘利用希尔伯特(Hilbert)变换能够得到电力系统振荡中电流信号包络线的特点,根据系统正常运行、纯振荡以及振荡中再故障情况下包络线的不同变化趋势,采用两相电流包络线之差的突变量作为判别量,提出了一种新型的振荡中再故障判别元件,该判别元件的计算精度不受电力系统振荡时频率变化的影响。大量 ATP 仿真证明了该元件在纯振荡过程中能够可靠不误动,并且可以快速有效地识别系统振荡中发生的各种故障。而且,文中采用的算法实现方便,计算量小,具有在工程中良好的实际应用价值。
文摘基于实时数字仿真器(real time digital simulator,RTDS)搭建了仿真模型,并将RTDS与实际直流输电控制及保护装置连接,建立了交直流混合系统实时仿真实验平台。在此基础上,针对"1.15"高肇直流极2闭锁事故进行了仿真研究,成功地再现了实际故障过程,并分析了事故发生的真正原因:直流极控装置误将瞬时故障检测为永久故障,终止直流线路重启;并提出了合理的改进措施:修改极控装置中接地检测故障装置和直流线路重启去游离时间。
