An approach to dynamic line rating state estimation at thermal steady state using direct and indirect measurements

Dynamic line rating has emerged as a solution for reducing congestion in overhead lines, allowing the optimization of power systems assets. This technique is based on direct and/or indirect monitoring of conductor temperature. Different devices and methods have been developed to sense conductor temperature in critical spans. In this work, an algorithm based on WLS is proposed to estimate temperature in all ruling spans of an overhead line. This algorithm uses indirect measurements - i.e. weather reports and/or downscaling nowcasting models as inputs as well as direct measurements of mechanical tension, sag and/or conductor temperature. The algorithm has been tested using typical atmospheric conditions in Iceland along with an overhead line´s real design, showing robustness, efficiency and the ability to minimize error in measurements.Fil: Alvarez, David L.. Universidad Nacional de Colombia; ColombiaFil: Faria da Silva, F.. Aalborg Universitet; DinamarcaFil: Mombello, Enrique Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Bak, Claus Leth. Aalborg Universitet; DinamarcaFil: Rosero, Javier A.. Universidad Nacional de Colombia; ColombiaFil: Ólason, Daníel Leó. Landsnet; Islandi

Conductor Temperature Estimation and Prediction at Thermal Transient State in Dynamic Line Rating Application

The traditional methodology for defining the ampacity of overhead lines is based on conservative criteria regarding the operating conditions of the line, leading to the so-called static line rating. Although this procedure has been considered satisfactory for decades, it is nowadays sensible to account for more realistic line operating conditions when calculating its dynamic ampacity. Dynamic line rating is a technology used to improve the ampacity of overhead transmission lines based on the assumption that ampacity is not a static value but a function of weather and line's operating conditions. In order to apply this technology, it is necessary to monitor and predict the temperature of the conductor over time by direct or indirect measurements. This paper presents an algorithm to estimate and predict the temperature in overhead line conductors using an Extended Kalman Filter, with the aim of minimizing the mean square error in the current and subsequent states (temperature) of the conductor. The proposed algorithm assumes both actual weather and current intensity flowing along the conductor as control variables. The temperature of the conductor, mechanical tension and sag of the catenary are used as measurements because the common practice is to measure these values with dynamic line rating hardware. The algorithm has been validated by both simulations and measurements. The results of this study conclude that it is possible to implement the algorithm into Dynamic Line Rating systems, leading to a more accurate estimation and prediction of temperature.Fil: Alvarez, David L.. Universidad Nacional de Colombia; ColombiaFil: Silva, F. Faria da Silva. Aalborg University; DinamarcaFil: Mombello, Enrique Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Bak, Claus Leth. Aalborg University; DinamarcaFil: Rosero, Javier A.. Universidad Nacional de Colombia; Colombi

Methodology to assess phasor measurement unit in the estimation of dynamic line rating

This paper presents a methodology to analyse the influence of both atmospheric variations in time and space and the error in synchrophasor measurements to estimate conductor temperature along an overhead line. In this methodology, expressions to compute the error propagation in the computing of temperature because of measurement errors and load variations are proposed. The analysis begins by computing overhead line's thermal and mechanical parameters using simulations of load and atmospheric conditions. Having computed these parameters, values of resistance, inductance and capacitance of the overhead line modelled by means of a π equivalent circuit are estimated, with the purpose of quantifying the sensibility of electrical parameters to changes in conductor temperature. Additionally, this analysis allows the identification of the temperature in each span along OHLs. Subsequently, the average conductor temperature is estimated using simulations of synchrophasors through the relationship between resistivity and temperature. This estimated temperature is compared with the temperature computed using atmospheric conditions to obtain the maximum error. This error is contrasted with the acceptable error margins. Thus, during the planning stage, this methodology can be used to assess PMU as a method of computing conductor temperature.Fil: Alvarez, David L.. Universidad Nacional de Colombia; ColombiaFil: Silva, F. Faria da. Aalborg University; DinamarcaFil: Bak, Claus Leth. Aalborg University; DinamarcaFil: Mombello, Enrique Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Juan. Instituto de Energía Eléctrica. Universidad Nacional de San Juan. Facultad de Ingeniería. Instituto de Energía Eléctrica; ArgentinaFil: Rosero, Javier A.. Universidad Nacional de Colombia; ColombiaFil: ólason, Daníel Leó. Landsnet; Islandi