Wind farm aggregation method based on motion equation concept: a case study

Abstract

With large number of wind farms integrating into grid, the dynamic behaviour of power system has been impacted significantly. To study the impacts of wind farm on power system, the dynamic modelling of wind farm is important. Compared with modelling all the wind turbines of wind farm in detail, aggregating the wind farm to reduce the complexity of model is a better choice. Several studies have put forward some aggregation methods, such as single-machine representation and multi-machine representation. However, applicability of these methods is limited and they cannot aggregate different types of wind turbines. This study proposes a wind farm aggregation method based on motion equation concept. By defining bus voltage as internal voltage of the aggregation model, the relationship between internal voltage and unbalanced power of wind farm is established. An aggregated model of wind farm in DC-link voltage control timescale is built and time-domain simulation results are presented to verify the feasibility of this model. The aggregation method can aggregate wind turbines regardless of their types and working status. In addition, this aggregation method can be applied to modelling other systems in other timescales based on motion equation concept.