The present work deals with active power balancing in embedded multi-terminal dc systems. The derived controller and grid control concept is able to achieve a significant improvement in power transmission deviations and excitation of oscillatory modes in the case of a converter outage.
Starting point for the design is the derivation of control requirements based on an analysis of state of the art converter control and dc grid control concepts in the context of active power balancing. The basic requirements are subsequently developed into design principles for a generalized controller and a derived tiered grid control concept.
The controller is designed based on a continuous integration of constant voltage, voltage droop and constant power control. This is achieved by a construction of the control characteristic and the subsequent gain scheduling
of the individual loops as well as the PI control gain.
Finally, the grid concept is described and simulated on a number of benchmark cases in order to show the effectiveness of the proposed controller and grid concept. Results show, that the defined control objectives can be achieved, i.e. the controller implements the grid concept, the system is stable for all operating points and power transmission deviations and the excitation of oscillatory modes is kept at a minimum
