Integration of Wind Power into Existing Transmission Newtork by Dynamic Overhead Line Rating Jiao Fu jfu03@qub.ac.uk D. John Morrow dj.morrow@ee.qub.ac.uk Sobhy M. Abdelkader s.abdelkader@qub.ac.uk Queen’s University Belfast, UK Abstract—In order to meet the renewable generation target, a large number of wind farms are planned to be connected to the grid of Northern Ireland (NI). However, the thermal limits of the transmission lines in the wind intensive areas will be a restriction with the increase of wind penetration. Instead of building new lines, dynamic line rating (DLR) which estimates the ampacity in real time based on weather measurements, provides an effective and economic solution to maximize the existing transmission assets to accommodate the wind generation. It is also anticipated that more wind generation can be delivered during windy periods as more line cooling is provided to the line. Field measurements have been taken on three 110 kV single circuits in NI network to evaluate the potential of DLR on line uprating. Also, the real-time generation of a nearby wind farm has been monitored such that the consistency of the wind power with the line capacity is investigated. Finally, the network analysis is performed to examine the system impact of DLR based on the IEEE reliability test system. Keywords-wind power integration; dynamic overhead line rating; transmission line uprating I. INTRODUCTION This paper addresses a solution to integrate wind power into the existing transmission system without network expansion. Wind farms are typically located at remote areas, which may be traditionally weakly connected, as the main transmission network was initially constructed to link the major generation sites and load blocks. For example, in Northern Ireland (NI), the wind intensive areas are mostly situated in the north and west, but the most populated area is in the east, along with the major conventional thermal plants. Currently, a large number of wind farms are planned to be connected in NI, in order to meet the target of 40% of electricity consumption from renewable generation by 2020 [1]. It is anticipated that a total of 1198 MW wind capacity to be installed by 2020 according to the local utility Power NI. Therefore, a big challenge faced by the network operator is to deliver the full wind generation at all times without thermal violation of the transmission overhead lines. Dynamic line rating (DLR) is considered as a solution to maximize the utilization of the existing transmission network for accommodating extra wind power. Traditionally, the static line rating is determined based on the conservative seasonal weather assumptions, which is likely to underestimate the actual capacity of the overhead lines. The average ambient temperature of 2 ºC, 9 ºC and 20 ºC in winter, spring/autumn and summer respectively is assumed in the UK Energy Association’s Engineering Recommendation P27 [2], along with an average wind speed of 0.5 m/s and negligible solar radiation. In comparison, dynamic line rating estimates the line ampacity in real time based on the weather data instantaneously measured from monitoring devices. It allows more power to be accommodated during the favourable weather conditions, especially with high wind speed. Therefore, it benefits wind power integration as more wind cooling can be provided to the line when higher wind generation is produced in windy periods. Line-rating methodologies, such as the IEEE [3] and CIGRE [4] models have been established to determine the line ampacity based on the thermal equilibrium between heat gain and heat loss of conductors. The main thermal contributors are illustrated as shown in Fig. 1, and directly relevant weather parameters are indicated as well. In general, magnetic heating, corona heating and evaporative cooling is not taken into account for model simplicity. Joule heating Magnetic heating Solar heating Corona heating Convective cooling Radiative cooling Evaporative cooling Ambient temperature Wind speed Wind attack angle Solar radiation Current Conductor temperature Figure 1. Major contributors to conductor temperature This work was supported by Science Foundation Ireland under the Strategy for Science, Technology and Innovation (2006-2014). This work was supported by Science Foundation Ireland under the Strategy for Science, Technology and Innovation (2006-2014).