The proportion of distributed generation (DG) connected to distribution networks is constantly increasing. Traditional protection schemes are insufficiently adaptable to distributed generation, and manual setting or methods based on enumeration cannot meet the requirements of distribution network setting calculation. This paper first analyzes the influence mechanism of distributed generation connected to distribution networks and proposes a short-circuit current calculation method for active distribution networks. Then, current instantaneous protection and overcurrent protection are analyzed respectively to determine the setting calculation method. The basis for selecting the equivalent bus is obtained by establishing a method to find the extreme value of the short-circuit current function. Finally, a distribution network setting calculation case is used to verify the accuracy of the setting calculation method determination proposed in this paper and demonstrate the relay protection setting method for active distribution networks.

The large-scale integration of high-proportion distributed power sources has an increasingly significant impact on the daily operation, dynamic control, and power restoration after faults of the distribution network. Therefore, it is necessary to effectively schedule and control the distributed power sources. To solve the problem of dynamic scheduling communication for a large number of DER in the distribution area, the IEC 61850 7-420 standard has standardized some information models for DER. However, the distribution areas mainly consist of medium and small-capacity DER, and their quantities are large with significant differences in communication conditions, making the aggregation management of DER in the distribution area face considerable implementation difficulties. Therefore, this paper analyzes the typical structure and information interaction requirements of the distribution area based on cluster control, and establishes a general information model for DER equipment based on the IEC 61850 standard to achieve dynamic resource scheduling of a large number of DER in the distribution area. Through data conversion from Modbus protocol to IEC 61850, the source-end dynamic conversion of inverter data is realized.

In order to solve the problems of interconnection and communication security of monitoring system the distributed energy resources (DER) with different ownership, the virtual power plant (VPP) can be effectively employed. This paper proposes the information model of DER monitoring terminal based on the IEC 61850-7-420, and studies the extensible message and presence protocol (XMPP) mapping to realize the real-time data communication service. The built-in security mechanisms TLS (Transport Layer Security) and SASL (simple authentication and security layer) of XMPP can ensure the security of information transmission. This paper also presents a platform to test the transmission performance of XMPP mapping, and the results show that XMPP properly meets the security communication requirements of DER monitoring system.

Accurate phase line topology identification of LV lines facilitates the handling of line faults, which is of great significance for the safe and stable operation of distribution networks. In this paper, we model and analyze the LV lines based on graph theory, and propose a phase line relationship identification scheme based on the combination of HPLC and k-means clustering for the problem of missing or dynamically changing phase line relationships of LV lines in the station area. Aiming at the known phase-line relationship in the station area such as distribution panel, two phase-line configuration schemes, Terminal extension and new phase-line description logical node PPLD, are proposed. The area is divided by combining the configuration information of IEC 61850 SCL and the information of metering automation system. If HPLC is configured in the unknown region, HPLC is used to identify the phase line relationship. If HPLC is not configured, k-means based algorithm is used for correlation analysis between voltage measurements. Example results from a place in Shandong show that the accuracy of the method proposed in this paper is 93.96 % on average, which is higher compared to the existing methods.Significance: Accurate identification of phase-line relationships in LV lines is essential for optimising load through phase-change switches. In this study, we propose a novel phase line relationship identification scheme that combines HPLC and k-means algorithm based on the existing equipment in the station area. Leveraging the known topology within the existing equipment (LTU, switchboard, etc.) in the station area, we introduce two phase line configuration schemes, Terminal extension (extending the known phase line relationship) and the new phase line description logical node PPLD (a novel approach for configuring known phase line relationships). Additionally, we suggest a method of regional division to recognise phase line relationships in unknown regions. If HPLC is configured, it is used for phase line identification; otherwise, a k-means based algorithm analyses voltage measurements. By tailoring identification schemes to the actual characteristics of the station area, we significantly reduce the amount of data to be identified, improving accuracy and resource efficiency.

新型电力系统的建设促使电力业务范围向用户侧深入,业务种类及数量不断增加.边设备资源有限,只能配置有限数量的服务,任务的时延能耗需求与设备资源有限的矛盾日益突出.为实现云边资源协同与任务的优化调度,提出了一种考虑服务配置的细粒度电力任务云边协同优化调度策略.通过建立微服务的时延与能耗模型,并对任务调度中的约束条件进行分析,将时延与能耗的优化决策问题转化为带约束的多目标优化问题,采用NSGA-Ⅱ算法求解.然后通过基于模糊逻辑的多准则决策方法为任务选择调度方案.仿真结果表明,所提策略在时延和能耗方面的性能优于其他策略,能够适应不同的任务场景并做出最优决策,提高了任务的完成率.

The AC series arc fault of low-voltage power lines is prone to electrical fires, causing personal and property loss.Given the sudden change of fault current amplitude and the arc randomness waveform characteristics of the current change,this paper proposes a recognition method based on the absolute difference of neighboring waves and randomness of the fault current. The method is based on the change law of the current abrupt change amount before and after the fault, and the abrupt change amplitude is used as the initiation criterion. Then an arc fault existence criterion is constructed based on the arc random characteristic time domain distribution of the current change amount during the fault cycle under different load types and air gap spacing. Finally, arc fault identification is achieved through a one-dimensional convolutional neural network（1DCNN） integrated. The average detection accuracy of the method using untrained trunk circuit data is 90.97% when the load power of the faulty branch circuit accounts for 20%. Thus this can effectively detect series arc faults with good adaptability.

Fires caused by electrical reasons such as short circuits and leakage in low-voltage distribution network lines account for a relatively large proportion of the high-rise building fires. Building an electrical fire monitoring system for high-rise buildings based on the Internet of Things (IoTs) technology can monitor electrical circuits in real-time and reduce electrical fires. Aiming at the interconnection and intercommunication of the information exchange of the IoT terminals in the electrical fire monitoring system of high-rise buildings, this paper firstly analyzes the functional communication requirements of the electrical fire monitoring system of high-rise buildings, and combined with the requirements of functional communication, the information model required for electrical quantity collection and non-electricity collection functions is studied based on IEC 61850, which is conducive to the fusion and application of low-voltage distribution network monitoring data and existing distribution automation system data. At the same time, the location information logical node is established by supplementing, which realizes the determination of the spatial position of the terminal and the sensor, the location of the fire source can be determined by analyzing and calculating according to the spatial location information and the spatiotemporal sequence of the detection information. Finally, the information modeling of different types of monitoring terminal equipment is carried out and the configuration suggestion based on SCL language is proposed. By realizing the integration of low-voltage terminal unit (LTU) into the system and the configuration of LTU, the standard system of IEC 61850 can be actually operated. A monitoring terminal based on the proposed information model has been developed and applied to a building in Wuhan.

The large-scale access of distributed power puts forward higher requirements for the monitoring of the distribution networks, and the topology identification of low-voltage power lines can effectively promote the integration of monitoring data and the distribution network information, effectively realizing the rapid identification of faults and ensuring the safety of users. In this paper, the method of graph theory was used to simplify the analysis of low-voltage lines, and the full topology identification strategy was proposed. Based on IEC 61850 SCL topology configuration information, line topology identification within the region was realized, and the correlation between regions was determined by the injection method. According to the configuration information, regional association information, and user’s collection information, the low-voltage station area line topology was divided into known regional topology and unknown regional topology. Aiming for the identification of line topology in the unknown region, according to the similarity of voltage fluctuations over short electrical distances, clustering analysis of user’s voltage data in the unknown region was carried out based on the k-means clustering algorithm. The test results showed that this scheme can realize the identification of topology in the region.

针对直流输电线路单端行波测距故障点反射波波头识别困难,利用直流线路过电压吸收电容接地端互感器二次侧电流间接获取线路故障行波,基于直流线路故障初始行波波前陡度和故障距离的关系,结合EMD分解IMF1 模极大值故障波头标记,提出了故障点反射波头的自动识别方法.对单端故障行波数据进行EMD分解,利用IMF1 模极大值标记各波头到达测量端故障的时刻;根据线路故障初始波头波前陡度计算初步故障距离,从已标记的波头中筛选与该距离最接近的模极大值点,确定故障点反射波,实现单端行波自动测距.在PSCAD/EMTDC中建立了±500 kV直流线路仿真模型,结果表明,所提算法能有效识别故障点反射波,在不同故障条件下算法具有较好的适用性.

由电网域向社会服务域延伸的配电网需要支持更多的业务,应用随新业务拓展不断增加可能会导致边设备资源不足.为了从边设备层面支撑资源受限情况下任务的调度与协同处理,提出了微服务架构下配电台区任务云边协同在线调度策略.从任务及设备角度对云边容器化场景下任务调度问题进行了分析,在容器化电力任务云边调度机制基础上,设计了优先级策略与任务分配策略,并通过改进的在线算法对任务进行实时调度.仿真结果表明,所提策略具有更高的任务执行效率,通过资源置换,能够提高边设备资源受限时重要任务的完成率以及系统安全性.

In the application process of distributed feeder automation (FA) that is based on peer-to-peer exchange of measurement and control data between smart terminal units (STUs), there is an urgent need for standardized communication interaction and necessary security protection. This paper proposes an IEC 61850 communication mapping scheme using built-in secure extensible messaging and presence protocol (XMPP) and the generic object oriented substation event based on the user datagram protocol (GOOSE over UDP) and a security protection scheme based on hash to obtain random subsets (HORS); one-time signature algorithm is used to ensure the communication safety of GOOSE messages. The agent-based distributed FA test system is developed with the STUs. The test results show the scheme can meet the requirements of the quick distributed feeder automation.

In order to solve the problem of interconnection and communication security of distributed energy resources (DER) monitoring system with different ownership, the virtual power plant (VPP) can effectively monitor and control DERs. this paper constructs the information model of DER monitoring terminal based on IEC 61850-7-420, and studies the XMPP mapping to realize the information model and real-time data communication service. The built-in security mechanisms TLS (Transport Layer Security) and SASL (simple authentication and security layer) of XMPP can ensure the security of information transmission. This paper builds a test platform to test the transmission performance of XMPP mapping, and the results show that XMPP can meet the security communication requirements of DER monitoring system.

Distributed control has good real-time performance and can better meet the control requirements of active distribution networks with a large number of distributed generations. Some distributed applications require real-time feeder topology to achieve control. In this paper, the demand for distributed control applications for feeder real-time topology is analyzed. Based on IEC 61850 modeling method, a new cell topology logic node and a new topology slice node are built to express feeder topology. Using the topology information of smart terminal unit (STU) configuration and the current status information of switchgear, based on the depth-first search, the feeder real-time topology identification can be realized, which meets the application requirements of distributed control. The study case verified the effectiveness of the method.

分布式馈线自动化(FA)需要馈线实时拓扑信息实现故障定位、隔离以及非故障区段的供电恢复.文中分析了分布式FA应用对馈线实时拓扑信息的需求,基于IEC 61850建模方法新建了单元拓扑逻辑节点和拓扑片节点以描述馈线拓扑.使用智能终端配置的拓扑片信息和当前的开关设备状态信息,基于深度优先搜索可实现馈线实时拓扑的识别,满足分布式FA应用需求,算例验证了方法有效性.

为实现分布式馈线自动化的智能终端间的互操作,保证终端的通信安全,文中提出了采用内置安全的可扩展消息和在线表示协议(XMPP)与基于用户数据报协议(UDP)的通用面向对象变电站事件(GOOSE)结合的IEC 61850通信映射方案.该方案使用基于哈希获取随机子集(HORS)一次性签名的安全防护方案以保证GOOSE报文的通信安全.在配电终端上使用该方案开发了基于代理式的分布式馈线自动化(FA)测试系统.测试结果说明,该方案能够满足速动型分布式FA要求.