Abstract :
Several substations on EDF Energy´s networks exhibit summer peaking characteristics. Previous load forecasting methodologies have estimated load growth on a regional basis, which is not suitable for analysing these types of substations. It will be shown that the most appropriate way to illustrate urban load characteristics is to correct demand for average cold spell (ACS) and average hot spell (AHS) temperature conditions at each substation. The IEC transformer loading guide [1] is suited to modelling standard transformers, which are sited outdoors. However, it is not appropriate for power transformers unable to readily dissipate heat such as those enclosed in basements or situated underground. A transformer thermal model has been developed which is based on the loading guide. Modelled transformer winding temperature data will be compared against actual winding temperature data to determine the thermal model correction factor for a particular enclosure. Determination of substation firm capacity can be facilitated by illustrating load and capacity, which are corrected to ACS and AHS conditions, on the same chart. This substation analysis tool is used to plan reinforcement to ensure networks comply with planning standards. It will be shown how the impact of network reinforcement solutions, such as increased transformer capacity and load transfers, can be modelled to achieve the best planning solution.
