A Distributed Dynamic Power Flow Algorithm for an Interconnected System Containing Two-Terminal LCC-HVDC Tie-Line

Abstract

In China, a growing number of regional power grids are interconnected by the line-commutated converter based high voltage direct current (LCC-HVDC) tie-line, forming a large-scale interconnected power grid. As the operation and control of the interconnected power grid are undertaken by multiple control centers, there is a demand for a distributed alternating current (AC)/direct current (DC) power flow algorithm. In this paper, a distributed power flow algorithm considering the LCC-HVDC tie-line is implemented based on the existing work of the author. The paper proposed some technologies to implement the algorithm. In the fixed-point iteration scheme of this paper, the combined boundary bus states are used to calculate the power flow of the DC system, thus the coordination of discrete state variables of the DC system is avoided. Also, the idea that converting the DC tie-line to an AC line is proposed to calculate the extended WARD equivalent of the external network of subsystems. Moreover, the unbalanced power distribution method is improved to make it more in line with the practical situation. Tests were carried out on the IEEE 118-bus system and an interconnected power grid constructed by six IEEE 118-bus systems, the correctness and effectiveness of the algorithm were proved.

Keywords

• Asynchronous iteration
• distributed power flow
• LCC-HVDC