870 / 2019-04-30 10:44:29

A new approach of simplifying dc transmission system to obtain coefficients of droop control

contraction,droop control,equipotential surface,inverter subset,rectifier subset

A new approach of simplifying dc transmission system to obtain coefficients of droop control in each station is proposed in this paper. Firstly, contraction is used to simplify independent nodes. Secondly, according to the direction of power flow, dc system is separated into rectifier subset and inverter subset. Then, choosing the minimum or maximum dc voltage in two subsets to circle the equipotential surface. Fourth, based on the equipotential surface, reshaping the dc system to obtain a new topology. Following, based on the impedance relationship in the subsets, droop control coefficients of each station are calculated. Furthermore, considering some stations which are connecting to the renewable sources or using V/f control strategy cannot control dc voltage, these kind of stations are not participated in the calculation. Finally, this new approach is verified based on the long-term planning of Zhangbei project.