Swedish Transmission Grid Model Based on Open Sources

Abstract

With new production units becoming smaller and smaller due to movement for renewable sources the electricity market contains an ever increasing amount of actors. The access to load flow data for smaller actors is limited due to security concerns making it difficult to perform pre-studies on the grid. A grid model of the Swedish transmission system has been created in the simulation software PSS/E. The model is based entirely on open sources which was one of the main aims of the project. The constructed model in PSS/E consists of 221 buses, 472 individual generators, 283 branches and 191 loads placed in the system. The 400 and 220 kV transmission model have been validated with the help of historical load flow data available from the power trading site Nord Pool and data made available publicly from the Swedish Transmission System Operator Svenska Kraftnät. Studies have shown that the average inter-trade deviation between the areas of Sweden is below 10% while it in most cases won’t differ more than a single percentage of the measured values. Transient stability studies have been performed in the model to compare the fault ride through requirement stipulated in the Swedish grid code. This was done to compare how conservative these requirements are in comparison to a real fault in the system. It was found that the voltage profile in some cases were more aggressive than what the measured voltage were on the generator bus. However, when applying a more realistic fault scenario including a disconnection of a faulted transmission line, the voltage profile was found in most cases to be too conservative as compared to the grid code requirement.