以电压源换流器为接口的分布式电源(distributedgenerator,DG)的故障电流完全由其控制策略决定,其传统的等值模型通常与常规电源类似,而忽视了控制策略的影响,造成含DG配电网故障分析存在局限性,尤其对于非对称故障情况。为此,首先对DG...以电压源换流器为接口的分布式电源(distributedgenerator,DG)的故障电流完全由其控制策略决定,其传统的等值模型通常与常规电源类似,而忽视了控制策略的影响,造成含DG配电网故障分析存在局限性,尤其对于非对称故障情况。为此,首先对DG的相间短路故障穿越控制特性进行分析,针对正序分量控制的DG提出了压控电流源等值模型;在此基础上,通过建立DG输出电流与公共联接点(point of common coupling,PCC)正、负序电压之间的关系方程式,推导出不同的相间短路故障条件下PCC正序电压的求解方程组,从而建立含DG配电网相间短路故障分析精确模型。基于DIgSILENT建立含DG配电网模型,仿真结果验证了该故障分析方法的正确性。展开更多
利用现有的低压电力线传输高速数据的PLC(power line communication)技术以其覆盖范围广、连接方便的显著特点而被业内人士看好,具有巨大的应用潜力,成为近年来各国研究的热点。本文详细介绍了低压电力线载波通信技术的原理、应用、发...利用现有的低压电力线传输高速数据的PLC(power line communication)技术以其覆盖范围广、连接方便的显著特点而被业内人士看好,具有巨大的应用潜力,成为近年来各国研究的热点。本文详细介绍了低压电力线载波通信技术的原理、应用、发展及特点,并就相关的关键技术问题进行了讨论。展开更多
The predominant use of today＇s networks is content access and distribution. Network Coding （NC） is an innovative technique that has potential to improve the efficiency of multicast content distribution over multiho...The predominant use of today＇s networks is content access and distribution. Network Coding （NC） is an innovative technique that has potential to improve the efficiency of multicast content distribution over multihop Wireless Mesh Networks （WMNs） by allowing intermediate Forwarding Nodes （FNs） to encode and then forward data packets. Practical protocols are needed to realize the benefits of the NC technique. However, the existing NC-based multicast protocols cannot accurately determine the minimum number of coded packets that a FN should send in order to ensure successful data delivery to the destinations, so that many redundant packets are injected into the network, leading to performance degradation. In this paper, we propose HopCaster, a novel reliable multicast protocol that incorporates network coding with hop-by-hop transport. HopCaster completely eliminates the need for estimating the number of coded packets to be transmitted by a FN, and avoids redundant packet transmissions. It also effectively addresses the challenges of heterogeneous mulficast receivers. Moreover, a cross-layer multicast rate adaptation mechanism is proposed, which enables HopCaster to optimize multicast throughput by dynamically adjusting wireless transmission rate based on the changes in the receiver population and channel conditions during the course of mulficasting a coded data chunk. Our evaluations show that HopCaster significantly outperforms the existing NC-based multicast protocols.展开更多
文摘以电压源换流器为接口的分布式电源(distributedgenerator,DG)的故障电流完全由其控制策略决定,其传统的等值模型通常与常规电源类似,而忽视了控制策略的影响,造成含DG配电网故障分析存在局限性,尤其对于非对称故障情况。为此,首先对DG的相间短路故障穿越控制特性进行分析,针对正序分量控制的DG提出了压控电流源等值模型;在此基础上,通过建立DG输出电流与公共联接点(point of common coupling,PCC)正、负序电压之间的关系方程式,推导出不同的相间短路故障条件下PCC正序电压的求解方程组,从而建立含DG配电网相间短路故障分析精确模型。基于DIgSILENT建立含DG配电网模型,仿真结果验证了该故障分析方法的正确性。
文摘The predominant use of today＇s networks is content access and distribution. Network Coding （NC） is an innovative technique that has potential to improve the efficiency of multicast content distribution over multihop Wireless Mesh Networks （WMNs） by allowing intermediate Forwarding Nodes （FNs） to encode and then forward data packets. Practical protocols are needed to realize the benefits of the NC technique. However, the existing NC-based multicast protocols cannot accurately determine the minimum number of coded packets that a FN should send in order to ensure successful data delivery to the destinations, so that many redundant packets are injected into the network, leading to performance degradation. In this paper, we propose HopCaster, a novel reliable multicast protocol that incorporates network coding with hop-by-hop transport. HopCaster completely eliminates the need for estimating the number of coded packets to be transmitted by a FN, and avoids redundant packet transmissions. It also effectively addresses the challenges of heterogeneous mulficast receivers. Moreover, a cross-layer multicast rate adaptation mechanism is proposed, which enables HopCaster to optimize multicast throughput by dynamically adjusting wireless transmission rate based on the changes in the receiver population and channel conditions during the course of mulficasting a coded data chunk. Our evaluations show that HopCaster significantly outperforms the existing NC-based multicast protocols.
