Equal Loading Rate Based Master–Slave Voltage Control for VSC Based DC Distribution Systems

With the increasing penetration of renewable resources and the DC nature loads, voltage source converter (VSC) based DC distribution systems take an important position in the future smart grid architecture due to many distinguishing features. However, DC distribution systems face frequent power disturbances and multi-mode swithcing problem, how to achieve better DC voltage control and reasonable power sharing performance under various disturbances is still a challenge. After analyzing the control structure and master-slave (M-S) method, an equal loading rate based M-S method is proposed based on the power sharing capability of the VSC station. Moreover, error analysis of the proposed M-S method is conducted and a correction method for the proposed M-S method is developed. The proposed M-S method not only preserves the advantage of M-S method, but also changes the power instructions accordingly based on the operation state of the whole DC distribution system. Moreover, the proposed M-S method is simple and easy to implement. Lastly, simulations of a three-terminal VSC based DC distribution system are conducted in PSCAD/EMTDC to validate the effectiveness of the proposed M-S method.