| The energy distribution area in my country is too far away from the power load demand area,and the energy base is 1000 to 4000 kilometers away from the load center,so energy needs to be distributed across regions.HVDC has become a long-distance large-capacity power transmission and regional grid interconnection due to its advantages of large transmission capacity,small transmission loss,and flexible adjustment.Important components are of great significance to the large-scale development and utilization of new energy in my country and the optimal allocation of energy across regions.In the process of widespread use of HVDC technology,commutation failure has become one of the major problems faced by the development of HVDC,which has seriously delayed the further application of DC transmission.The reactive power compensation device connected to the receiving end AC bus in the HVDC system can provide voltage support in the event of a fault,which can effectively reduce the commutation failure.In recent years,new energy power generation units have gradually increased,and the market prospects for large-scale energy storage have become increasingly apparent.This paper considers the addition of reactive power compensation on the basis of energy storage,and proposes a commutation failure suppression technology based on large-scale energy storage.The main work content is as follows:(1)The development process of HVDC technology is introduced,and the advantages and disadvantages of various reactive power compensation methods to suppress the commutation failure of the HVDC system are analyzed.This paper introduces the advantages and application scenarios of large-scale energy storage technology,as well as the current research status of the topology and control strategy of large-scale energy storage converters,and considers adding reactive power compensation on the basis of energy storage to suppress commutation failure.(2)Starting from the structure of the HVDC transmission system,the on-off process of the thyristor and the commutation process of the converter valve of the inverter station are analyzed,the calculation formula of the extinguishing angle is deduced,and the internal factors leading to the failure of the commutation are studied.And external factors.(3)The topology structure of the large-scale energy storage converter is studied,the mathematical model of the large-scale energy storage converter is deduced,the positive and negative sequence control strategy of the current inner loop is proposed,and the large-scale energy storage converter is verified by simulation.When the receiving end system fails,it can support the grid-connected point voltage and has the ability to suppress commutation failure.(4)Designed and developed a 250 k VA large-scale energy storage converter device,including device selection,hardware circuit design and software flow design.The gridconnected test verifies that the large-scale energy storage converter device can effectively support the grid-connected point voltage.The developed device is connected to the 1600 V HVDC physics simulation platform to carry out the commutation failure suppression effect experiment.The experimental results verify that the large-scale energy storage converter device has the commutation failure suppression capability. |
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