Operation Scenario and Coordination Control of DC Grid with DC-DC Converters

Author(s):  
Meiyan Wang ◽  
Ke-Jun Li ◽  
Kaiqi Sun ◽  
Zhijie Liu

Background: With the increasing development of voltage source converter based high voltage direct current (HVDC), it will become a reality to interconnect different DC networks into DC grid with DC-DC converters. Methods: In this paper, three operation scenarios for the DC grid with DC-DC converters are proposed, by which the DC networks can reinforce each other with relative independence. In order to achieve the flexible switching of the proposed scenarios, the DC-DC combined control and principle of parameter selection are presented. In addition, two coordination controls for different scenarios are given to optimize the distribution of unbalanced power when the disturbances occur in the grid. With the proposed scenarios and control strategy, the impacts caused by the disturbances are alleviated and the uninterrupted operation of the grid is guaranteed. Results: A simulation model is established on the PSCAD/EMTDC and the simulation results verify the effectiveness of the proposed operation scenarios and control strategy. Conclusion: Finally, the effectiveness of the proposed operation scenarios and control strategy is verified by the simulation results in PSCAD/EMTDC.

2014 ◽  
Vol 521 ◽  
pp. 222-228
Author(s):  
Kai Wang ◽  
Hai Shun Sun ◽  
Yu Hua ◽  
Yuan Liu ◽  
Wei Xing Lin ◽  
...  

The continuous development of alternative energy has put forward higher requirement for electricity transmission. To cope with its fluctuation characteristics, high voltage direct current (HVDC) technology has received more attention. Voltage Source Converter (VSC) based Multi-Terminal High Voltage Direct Current (MTDC) represents the future trend of HVDC technology. This paper mainly focuses on the control strategies of a four-terminal VSC based MTDC power transmission system. The operation characteristic of the system was studied, and the proposed two control strategies, master-slave control strategy and DC voltage droop control strategy, were verified through simulations. The latter control strategy was proved to be performing well under various conditions, including converter station disconnection and faults at AC side of the converter.


2013 ◽  
Vol 3 (2) ◽  
Author(s):  
Guo-Jie Li ◽  
Si-Ye Ruan ◽  
Tek Lie

AbstractA multi-terminal voltage-source-converter (VSC) based high voltage direct current (HVDC) system is concerned for its flexibility and reliability. In this study, a control strategy for multiple VSCs is proposed to auto-share the real power variation without changing control mode, which is based on “dc voltage droop” power regulation functions. With the proposed power regulation design, the multiple VSCs automatically share the real power change and the VSC-HVDC system is stable even under loss of any one converter while there is no overloading for any individual converter. Simulation results show that it is effective to balance real power for power disturbance and thus improves operation reliability for the multi-terminal VSC-HVDC system by the proposed control strategy.


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