摘要
自同步技术在线路差动保护中发挥了重要作用。GPS既可以为非交换网络也可以为交换网络正确完成同步。作为一种备用同步方式,乒乓技术只能在非交换网络中正确动作,因为此时发送和返回通信通道是一致的。作为对GPS的补充,在将本侧电流和电压相量和对侧传送来的相量值比较的基础上,提出了各种不同的自同步技术。这些技术只适用于双端,或多终端但只有一个T接点的输电系统中。针对有多个T接点的多端输电系统提出了一种自同步新技术。通过利用节点阻抗矩阵和对侧的等量阻抗,可以在本侧计算出流入远方终端的节点电流。然后通过将计算出的节点电流与对侧传来的电流数值相比较,可以计算出时间差。故障时,可以利用故障探测器闭锁自同步功能。提供的算式可以扩展应用到任何电力系统的拓扑网络。大量的仿真试验数据表明,计算出的时间延迟数值最大误差低于0.08ms,远远低于差动保护所要求的数值。此技术已经在商业产品中运用。
Synchronization techniques play a very important role in the line differential protection.GPS can provide synchronization properly for both non-switched and switched networks.Ping-pong technique as a backup synchronization method can only run properly in non-switched networks where the forward and return communication paths are same.As a complement of GPS,various self-synchronization techniques have been proposed based on comparing the current or voltage phasors from local end with those phasors being sent from remote end.These techniques are only adaptive for two-ended transmission systems or multi-terminal with only 1 junction.This paper proposed a new technique of self-synchronization for multi-ended transmission system with multi-junctions.The junction current flowing into the remote end is calculated at local end by using the node-impedance matrix and the equivalent impedances of remote terminals.The time differences are calculated by comparing the calculated junction currents with those sent from sent form remote end.A fault detector is employed for freezing the self-synchronization function during the fault.The proposed algorithm is scalable for any topology of the power system.The validations by large amount of COMTRADEs show that the maximum error of calculated time delay is less than 0.08 ms which is much lower than the requirement of differential protection.The technique is now being implemented into commercial products.
作者
哈恒旭
王翀(编译)
叶远波(编译)
HA Hengxu(GE Grid Project Division UK Co.,Ltd.,Stafford,England)
出处
《电力与能源》
2018年第6期744-751,共8页
Power & Energy
关键词
电力系统保护
多端电流差动保护
多端输电线路
自同步
Power system protection
multi-ended current differential protection
multi-ended transmission lines
self-synchronization
