A parallel restorative control strategy for a simple dc system after severe fault

In recent years, the applications of dc transmission method become more and more popular with the fast development of power electronics technology. The dc systems may face various kinds of faults during actual operation and the corresponding control strategies against these situations are of great significance to make the system keep stable operation. In this paper, a simple dc system topology structure is proposed, and the corresponding operating principle of each component in the dc system is discussed. On the basis of constructed theoretical formula of each component, the simulation model of the proposed dc system is built under the PSCAD/EMTDCTM environment. The fault characteristics of the dc system against a dc single-line open fault are elaborately studied based on the model. Consider that such dc line fault may lead to partial outage of the dc system, the appropriate restorative control strategy is required after the fault. This paper designs a parallel restorative control strategy to keep the dc system returning to the normal operation status after the fault clearing. Finally, the simulation results are carried out to demonstrate the feasibility and validity of the proposed dc system recovery strategy.