Research On Integrated Control Of Grid Splitting And Paralleling Operation Based On VSC-HVDC

The construction of smart grid urgently needs the grid to realize self-healing control in more links and improve the sy'stem self-recovery ability. At present, for the grid splitting and paralleling have been carried out a large number of studies, but the organic combination of the two aspects of the grid to achieve self-healing research is little. The grid operation is a continuous organic whole, and it must be involved in the recovery paralleling after the system splitting. It is of great significance to realize the integrated control of the grid splitting and paralleling after splitting. Based on the study of the grid synchronization paralleling by VSC-HVDC , and combined with the out-of-step splitting criterion, this paper studies on the integrated control of grid splitting and paralleling, to enhance the ability of grid automatic recovery and reduce the accident loss.Firstly, the methods and principles of VSC-HVDC to realize grid synchronization paralleling are introduced, and the control strategy of VSC-HVDC grid paralleling system is analyzed. Secondly, it is proposed to add the out-of-step criterion to the VSC-HVDC grid paralleling system controller, so that it has the splitting control function. This paper analyzes and studies the existing out-of-step splitting criterion. In order to solve the problem that the grid paralleling operation and the out-of-step splitting criterion in the integrated control may conflic,this paper proposes a composite criterion based on the starting criterion of the weighted avcraee current of the tie line and the criterion of Ucoscp criterion as the main criterion,which effectively solve the problem of zero crossing of Ucosip in the process of grid psaralleling. The simulation model is established in PSCAD / EMTDC software. The integrated control strategy of compound system is analyzed and the corresponding control module is prepared. The corresponding control module is written to verify the realization of the two functions in the conposite system.The simulation of the combined control of grid splitting and paralleling is carried out.The simulation results slhow that the proposed method can effectively control grid splitting and fast reconnection after fault removal.and realize a certain degree of grid self-healing function.Finally, based on the theoretical research and simulation results, the experiment of VSC-HVDC composite system is carried out. The main program, SVPWM algorithm and ADC acquisition program are prepared. Experiments are carried out on the prototype platform of VSC-HVDC composite system based on TMS320F2812. The correctness of the program algorithm is verified.