Review of Transient Overvoltage in UHVDC transmission Sending-End System

When ultra-high voltage direct current (UHVDC) is used for external wind power transmission, typical ACIDC faults in the transmission sending-end system may cause transient overvoltage problems. In severe cases, it can cause wind turbines disconnected from the grid, endangering the stable operation of the power grid and hindering DC transmission, thereby restricting wind power consumption. The characteristics research and overvoltage control of transient overvoltage problems in this system are summarized from four aspects: two typical transient voltage response characteristics and their mechanisms, simulation and quantitative analysis methods, relevant standards for transient overvoltage, and response strategy design. Starting from recent wind turbine disconnection accidents, the voltage response characteristics and influencing factors are sorted out. Analyzed the formation mechanisms of two types of transient overvoltage: from low to high and short-term jump, and reviewed the methods of transient overvoltage quantification and simulation modeling analysis. Elaborated on the development process of relevant standards and specifications, while also exploring the issue of insufficient coverage of overvoltage regulations for grid connection points in current standards and proposing suggestions. Based on the hierarchy of inhibitory strategies, compared and analyzed the advantages of single objective control and the limitations of multi-objective collaborative control of existing strategies from the control and system levels. The follow-up research on the transient overvoltage problem of the UHVDC sending-end system will be further developed based on these bases.