Simulation of dynamic power flows in the international grid control cooperation

In the past, the organization of the procurement and activation process of control power was primarily a national task in the European transmission grid. Since 2011, Denmark and Germany cooperate in the international grid control cooperation (IGCC) to avoid the counter activation of secondary control power and therefore to lower their costs. Today seven countries participate in the IGCC [1] and it is designated, to expand this cooperation in the future [2]. However, the international cooperation means that control power has to be transferred between the IGCC participants. As a result, additional control power flows occur. These control power flows have an impact on the grid utilization, especially on the interconnectors, which have to transfer the control power between the countries physically. To avoid interconnector overloads, a congestion management (CM) is implemented [3]. In this paper an approach for the integrated calculation of power flows and frequency in the IGCC is presented. For this purpose, the standard model for the analysis of frequency control is combined with a power flow analysis. As a result of this approach, the dynamic changes of the grid utilization in an IGCC can be simulated. The resulting model is used to simulate dynamic power flows in an eight-node system, considering the IGCC and its CM. It is shown that the CM is neither able to avoid overloads exactly nor to ensure an optimal utilization of the existing transmission capacity. This means, the CM is subject to a certain inaccuracy. In the future the presented model can make a contribution towards checking the CM accuracy at the European level and towards developing enhanced CM methods with an improved accuracy.