Decoupling power systems analysis using hybrid load flow calculation

A large number of new and decentralized energy conversion systems (ECSs) in combination with renewable energy sources (RESs) have recently been integrated into the conventional grid to build up sustainable energy supply systems. This is one of main challenge of future smart grids. Thus, currently there are plenty researches focusing on the grid integration such as clustering concept. By clustering concept, it has a possibility to form the distributed generation (DG) units in a small group, which can establish an advance control function in order to make this small group to behave like a virtual power plant. Therefore, the grid integration can be completed in an easily way. However by adding the new grids, the fluctuation of dynamic behavior can cause the unstable power systems, for example, the voltage profile can temporally be out of the nominal rated condition. To avoid the unstable condition, the basic description such as the power flow between connected- or decoupling positions must be clarified and analyzed. In general analysis, the power system analysis needs to recreate the model structure when the new grid is joining the existing grids. This results in an increased complexity of power system analysis. Therefore, this paper introduces the decoupling power system analysis, which can analyze separately on each grid and no need to recreate new model when power systems structure is changed by adding the new grid. To validate the proposed method, the simulation case studies are provided and the results prove that the proposed method can be utilized as the general analysis method.