Physical Controller Design Of HVDC System Based On MMC Topology

The application of the modular multilevel converter-high voltage direct current (MMC-HVDC) has been increased when the abundant DC constructions have been carried out in domestic by recent years due to the advantange of high quality output waveform and fast response. The converter as the key part of the HVDC flexible system has been developed from low voltage and small volumn to high voltage with ±350kV busbar and high volumn with 1000MW or even higher. These new developments raised the higher requirement for the converter control system. This paper kept eyes on this development tendency, carried out the research and design work on the MMC-HVDC system physical controller, and developed the engineering hardware platform for inverter and thyristor valve controller based on the analysis of the object characteristics and engineering requirement.This paper gave a brief introduction for the topology structure of the convertor comprised by the half brige sub model first, and then analysed the convertor working principle based on the full-controlled switch and electromagnetic transient mathematical model, summarized the function and performance requirement for the hardware platform of system controller. Then the muti-level redundant structure of MMC-HVDC system physical controller has been created based on the engineering requirement and hierarchical control concept. This new design focused on the hardware structure of the inverter and thyristor valve controller, and adopted the plug-in card type controller with back and sub-card.Eight types of the functional card have been designed, and the hardware platform of the controlled has been set up based on the main controller's performance analysis including calculation control, device connecting and data communication. The circuit design has been introduced from circuit structure and component selection. The serial rapidIO (SRIO) with high real-time feature has been adopted as point-to-point communication protocol, and been verified by the communication with IC on main board.Finally the reliability of the controller has been researched based on three aspects which are environmental conditions, mechanical strength, and electromagnetic compatibility, and then the improvement work has been carried out to enhance the reliability of the controller, and made the controller to achieve the target property. The new designed hardware platform of the controller passed the type test, and has been verified in the engineering project application.