Weather conditions based wide area Dynamic Line Rating system for 110 kV network monitoring and contingency analysis

摘要

The paper describes a Dynamic Line Rating (DLR) system integrated with SCAD A/EMS. Presently it is used by a number of Distribution System Operators in Poland for real time 110 kV overhead lines ampacity monitoring and network contingency analysis. The reasons for deploying such a system are mainly: spot load growth, expansion of wind farms generation and ageing infrastructure. The paper presents the system deployment stages, as based on up to date practice: (1) Choice of the optimized location for weather stations based on a set of defined criteria. In most cases weather stations are installed on the towers. (2) Selection of the so-called "critical spans", that is the spans where the ground clearance is the smallest along the line. The critical spans are later on continuously monitored by the software system. Choice of the critical spans is based on the data obtained from laser scanning of each 110 kV line and processing the data to determine ground clearance line profile for the defined temperature. The line rating for each line is calculated based on the measured weather conditions (ambient temperature, wind speed and direction, solar irradiance) and conductor mechanical parameters connected with selected critical spans. Over the course of years of system operation it has been possible to collect comprehensive real measurement data sets from weather stations located in different locations. Corresponding measurements of the conductor temperature and actual load have been recorded. Such approach resulted in creating a very accurate line thermal model for different types of HV lines, differentiated also with regard to the line age and conductor surface state. Continuous real time data exchange with the SCADA systems - especially line current - allows the actual ground clearance as well as the percentage of used line capacity to be determined. Consequently SCADA systems can issue warnings regarding possible line overload resulting in breaching the admissible line clearance limit. The data exchange between DLR system and SCAD A/EMS system is based on XML files and SOAP oriented architecture.