Design of the Monitoring System for Power Distribution Area by Clean Energy Intelligent Integration Terminals

Abstract Power distribution area is an important part of low-voltage distribution network. Because of its wide distribution and complex environment, it often causes large area blackout or even worse. As the core equipment in the automation construction of low-voltage distribution network, the monitoring and management level of distribution network will be directly affected by the performance of intelligent transformer terminal. The traditional intelligent transformer terminal and concentrator belong to the two departments of operation and distribution, and there are some problems, such as non-sharing of data, duplication of functions, increasing the workload of operation and maintenance. In view of the above defects, this paper puts forward the concept of intelligent integration terminals, which has the functions of intelligent transformer terminal and concentrator. Based on this terminal, a set of power distribution area condition monitoring system is designed, which can realize the function of low-voltage distribution station area condition information monitoring, low-voltage line topology identification and branch line loss analysis. While the construction cost of power distribution area is reduced, the intelligent management level of the low-voltage distribution network can also be comprehensively improved.</jats:p

Research on Status Monitoring and Fault Alarm Device of Drop-out Fuse

Abstract Drop-out fuse is a common circuit protection device. When a short fault occurs in the circuit, the fusion pipe will drop and the fuse will be disconnected, so as to isolate the fault line. However, in practical application, there is no reliable means and device for remote monitoring, resulting in the failure information can not be found in time. Although the traditional drop-out fuse alarm device can play the role of fault alarm. It has the disadvantages of large time difference and high cost. Based on this, a set of status monitoring and alarm device according to the drop characteristics of drop-out fuse after failure has been developed. The inclination and temperature of the fusion pipe are monitored by sensors in real time, and the data is sent to the master station through wireless communication. When a fault occurs, the operation and maintenance staff can be notified in time to repair the fault point. Through experimental demonstration, it can be concluded that the fuse status monitoring and fault alarm device has stable performance, convenient control and high cost performance. If it is applied to the distribution network, it can shorten the outage time, reduce economic losses and increase user satisfaction.</jats:p

Research on Power-Frequency Overvoltages of 220 kV Offshore Cable Transmission System in Liaoning Province

Abstract Since power-frequency overvoltages can influence the safe operation of the submarine cable transmission system greatly, it is indispensable to calculate the overvoltages that may occur during actual situations. In this study, the power-frequency overvoltages of the offshore oil-gas field group’s submarine cable transmission system are calculated through PSCAD/EMTDC. Among the different conditions considered, the maximum power-frequency overvoltage is 1.134p.u., which occurs in the case of single-phase fault earthing at the cable joint in L4. The result fulfills the limit of relevant regulations for the 220 kV transmission system, indicating that the submarine cable transmission system can operate safely and effectively, which can provide important guiding significance for the construction and operation of the system.</jats:p

On-site Insulation Tests for MV cable using Very Low Frequency and Damped AC Techniques

MV cables are vital components in urban power networks. Several insulation test techniques are proposed for guaranteeing the operation of MV cables. In this paper, two kinds of off-line testing techniques are introduced, namely Tanδ measurement using VLF and PD detection using DAC. Firstly, the operation principle of each technique is introduced. Then, a simulation model was built in Simulink platform to demonstrate the operation processes of detecting the defects in the cable. At last, an on-site case using both VLF and DAC techniques is introduced for presenting the functions of different techniques.</jats:p