Technical gazette, Vol. 30 No. 4, 2023.
Original scientific paper
https://doi.org/10.17559/TV-20220806130349
Smooth Regulation of DC Voltage in VSC-MTDC Systems Based on Optimal Adaptive Droop Control
Ping He
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Xiaowei Zhang
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Congshan Li
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Lei Yun
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Hua Yang
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Yabang Yan
; School of Electrical and Information Engineering, Zhengzhou University of Light Industry, 450002, China
Abstract
DC voltage stability and power balance are the key conditions for stable operation of DC transmission systems. The droop control does not depend on inter-station communication and has the advantage of multi-station cooperative unbalanced power dissipation, which has been widely used in the voltage source converter based multi-terminal direct current (VSC-MTDC) system. However, its control will cause DC voltage deviation, and there are a series of problems such as unstable system control and overload operation of the VSC-station due to improper setting of droop coefficient. In this paper, the infeasibility of DC voltage error-free correction under droop control mode is theoretically analyzed, and a VSC-MTDC cooperative optimization droop control strategy with DC voltage "quasi-error-free" adjustment ability is proposed. The strategy adjusts the droop coefficient in real-time by monitoring the DC voltage deviation and the power margin of the VSC-station to solve the problem of voltage deviation caused by unbalanced power consumption. At the same time, an additional DC voltage stabilizer is designed to automatically adjust the power reference value and restore the DC voltage. Finally, a five-terminal VSC-MTDC system is built under PSCAD/EMTDC to verify the feasibility of the proposed strategy.
Keywords
DC voltage deviation; droop control; power margin; VSC-MTDC
Hrčak ID:
305474
URI
Publication date:
28.6.2023.
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