There are three main challenges for developing the coordinated TDC system restoration approach to speed up the entire system restoration:

1. Lack of a mechanism for sharing necessary information among transmission operators and distribution utilities to coordinate the restoration plans both at the planning and actual implementation stages;
2. Limited knowledge and lack of established models for the communication systems used for power system control and operation;
3. Lack of support tools for providing operators and engineers coordinated restoration procedures which are adaptive to evolving system conditions.

The PNNL team has developed a mechanism for sharing necessary information between transmission and distribution entities for coordinating restoration plans at both the planning and the implementation stages. The team will continue to develop a synthetic communication model with realistic features and coupled with the T&D systems, and algorithms for identifying the interdependence and the critical parts in T&D&C systems). The team will provide a tool for generating time-sequential, coordinated restoration plans. The work plan is shown in Figure 2.