Transient Overvoltage Control Strategy In New Energy Sending-End Grid Based On HVDC Blocking Fault

The reverse distribution of new energy and load center makes HVDC an important way of new energy consumption.With the continuous growth of the scale of long-distance HVDC,the transient overvoltage in the sending-end grid caused by HVDC blocking fault is easy to cause the high-voltage trip-off of wind turbine,and the risk of safe operation of wind turbine increases,resulting in the "invertion" relation between HVDC and wind power,which becomes the bottleneck restricting the large-scale wind power transmission and consumption.Therefore,this paper studies the characteristics and control mechanism of transient overvoltage caused by HVDC blocking fault,and proposes a transient overvoltage control strategy in new energy sending-end grid.Firstly,this paper analyzes the transient voltage rise characteristics at the rectifier station caused by HVDC blocking fault and its conduction characteristics in the new energy sending-end grid.And then.this paper analyzes the reactive power regulation characteristics of voltage control equipment.and determines the response delay and controllable parameters of the equipment according to the control system transfer function.Then,based on the equivalent circuit of wind-HVDC system,aiming at the equipment that can be used for transient control,the control mechanism of the transient overvoltage after HVDC blocking fault is studied.Secondly,a transient overvoltage control strategy based on HVDC blocking is proposed.Based on the conduction characteristics of transient voltage rise in the sending-end grid,a hierarchical sequential control mode of "rectifier station-wind farm" is proposed,and action sequence of each layer is analyzed.Then,taking the peak value of transient overvoltage at the rectifier station as the control objective and the controllable parameters of synchronous condenser as the control objects,a centralized control model for rectifier station considering the HVDC power is established.Besides,taking the peak value of transient overvoltage at the wind farm as the control objective and the controllable parameters of SVC and DFIG as the control objects,a decentralized control model for wind farm considering the wind power is established.Both models are solved by combined invocation method.Based on the hierarchical sequential control mode and model,the transient overvoltage control strategy in new energy sending-end grid is proposed.Finally,based on the operation data of a HVDC and sending-end grid,the simulation results verify the feasibility and effectiveness of the proposed strategy.