A Micro Switch Based Modeling Method for LCC-HVDC System

Power system simulation is an important tool to analysis the mechanism and characteristics of high voltage direct current (HVDC) systems. With the increased transmission lines in system, the calculation amount and complexity of simulation increase greatly. The line commutated converter (LCC) is the most widely used converter in HVDC system. The average model of LCC lacks the commutation process and can only be used for steady-state analysis. The switch model is too detail for large system simulation, making the calculation amount too large. Therefore, a modeling method based on micro switch is proposed for LCC in this paper, which reflects the commutation process of converter but has less calculation. Firstly, the basic concept of micro switch is introduced. Secondly, the external characteristics of the active inverter are analyzed. Then, the process of LCC commutation is analyzed to express the characteristics of thyristor unit. Finally, the effectiveness of the micro switch modeling method is verified by simulation. Compared with the switch model, the proposed model can effectively shorten the simulation time, and retain the inverter commutation process, and further simulate the commutation failure scenario in the future.