The Research On The Configuration Method Of The Frequency Controller To Suppress The Transient Overvoltage Of The Wind Farm Under The DC Disturbance

With the large-scale development and utilization of wind power generation technology in China,UHVDC transmission technology has played an extremely important role in the long-distance transmission of large-scale wind power generation.To a large extent,it alleviates the form of wind power consumption in China's wind intensive areas,and also improves the optimal allocation of energy in China.However,the stability problem of the wind power transmission system through DC is also more prominent.If the DC system has commutation failure,single and double pole blocking and other disturbances,the AC system at the sending end will appear more serious transient overvoltage phenomenon,which may cause a large area of over-voltage disconnection of the near area wind farm,and further expand the grid fault.Synchronous condenser has strong reactive power regulation ability,which can quickly provide dynamic reactive power/voltage support for DC sending end system,and effectively suppress the transient overvoltage risk of DC sending end system.But the research on suppressing overvoltage by synchronous condenser is relatively less.In this paper,the reactive power allocation scheme to reduce the transient overvoltage risk of DC sending end system by using synchronous condenser is studied,which has far-reaching theoretical and practical significance.The specific contents are as follows(1)The principle of transient overvoltage in near DC region caused by different DC perturbations is analyzed.Taking the actual data of a power network in 2023 as an example,the influence of different fault types,different rectifying side system strength and different DC operating power on the transient overvoltage of the transmission end system is simulated,and the influencing factors leading to the severity of the transient overvoltage of new energy are summarized.A large-scale new energy DC transmission test simulation system was built on the PSD-BPA electromechanical transient simulation platform.The effects of the layered and decentralized configuration of the synchronous condenser were studied,and the effects of the centralized and decentralized access of the synchronous condenser with different voltage levels on reducing the risk of transient overvoltage in the DC sending system were considered.(2)This thesis proposes a dynamic reactive power location scheme for reducing transient overvoltage of new energy sources near DC area by using synchronous compensator.Combined with the definition of Short Circuit Ratio(SCR)and considering the output characteristics and output probability of wind farms,a severity of transient overvoltage risk index(STO)and dynamic sensitivity of STO(SS_i)were proposed.A complete large-scale new energy DC delivery system reactive power compensation site selection optimization model is constructed,which can effectively locate the best dynamic reactive power compensation site of the new energy DC delivery system.(3)After the reactive power compensation sites have been determined,a dynamic reactive power constant capacity adjustment scheme is proposed to reduce the risk of transient overvoltage in the DC transmission end system.The method aims at the optimization goal of synchronous condenser to reduce the transient overvoltage risk of new energy in the near DC area and the lowest sum of the dynamic reactive power compensation cost of synchronous condenser.The installed capacity of synchronous condenser at the established site is used as a variable,and the artificial intelligence PSO algorithm is adopted by writing code The program enables Python and PSD-BPA to perform joint interactive simulations,and to perform fully automated processing of related data,to obtain the optimal reactive power configuration capacity for the established site to reduce the risk of transient overvoltage in the DC transmission end system by synchronous condenser.Finally,based on the actual power grid system example in 2023,the validity of the model and method is verified.The simulation results show that the dynamic reactive power compensation can not only improve the stability of the AC/DC power grid system at the sending end,but also reduce the risk of transient overvoltage of new energy at the sending end of the DC system.