Research on the structure and implementations of the DC grid power control

Due to various outstanding advantages, the DC power grid has a great potential to be used in the future power grid. The design of structure and strategies of the power control is a fundamental issue of the planning, construction and operation of the DC power grid. By analyzing the similarities and differences between the ac and DC power grid control system' functions in controlling executors, the control objects, the power characteristic curves, the response speeds, and so on, each single layer's structure and function of the power control system were defined. The primary control layer is responsible for the DC voltage stability, the secondary one is in charge of the power transmission according to the dispatching orders, the third one aims at the economic load dispatching, the forth one focuses on the fault insulation and resume in the enormous range of time scales. The former three control functions are applied in the normal operation conditions, and the last one works in the occasion of the grid structure changing and the operation conditions switching. The control strategies, the operation modes and the technical routes of each layer were investigated. The key parameters and coordinations skills among different layers were studied, including the transferring calculation results, the controlling of responsive speeds, the treatment of communication delays, the ordering of updating periods and so on. The key factors, such as the reserve capacity, the communication conditions, the short-crcuit capacity of the ac systems, etc. were also studied. The proposed scheme in this paper has lots of advantages, such as utilizing the existing ac technical and managerial experiences, being The National High Technology Research and Development of China 863 Program (2015AA050101); Key Technology Project of State Grid Corporation of China (5455DD150008, 5455DD150015) compatible to the present technological and managerial structure, improving the research level and speeding up construction steps of the dc power grid. Meanwhile, the author also suggested that further studies should especially focus on promoting the control structure standard, increasing the strategies design differentiation, improving the simulation efficiency, increasing the research methods etc. © 2015 Chin. Soc. for Elec. Eng.