Research On Optimal Allocation Of The Separation Device Of Transmission Channels Integrated To Large-scale Wind Power

In recent years,domestic wind power installed capacity has shown a rapid growth trend.The “Three North” region is rich in wind energy,and the load center is in the southeastern coastal provinces,which has caused the inverse distribution of load and wind energy.And a development model of large-scale pooling of wind energy,largecapacity,long-distance transmission and consumption through high-voltage / UHV AC / DC transmission channels has been formed.When the problem of the transient angle instability occurred in the power system due to an extremely serious fault,the oscillation center was often located on a long-distance AC channel.Therefore,configuring separation device on the channel was an effective means to block the impact of serious faults on the system.After the wind power was integrated,its characteristics such as low fault ride-through capability and weak reactive power support affected the transient stability of the system,and then interacted with the operating characteristics of the separation device.If the separation device cannot operate effectively,it may lead to the expansion of the accident,or the separation device may cause a large-scale off-grid of wind power in the near area,causing a secondary impact on the system.The risk of coupling operation of wind power and transmission channels was increased.Therefore,it was of practical significance to study the optimal allocation of the oscillating disassembly of the delivery channel under the wind power and thermal power centralized access.First of all,this paper established a model of doubly-fed induction generator(DFIG),a wind farm equivalent model,and separation device models with different principles.A single-machine infinite system model with centralized wind power and thermal power had been built on the power system simulation software PSD-BPA.Then,based on the single-machine infinite system with centralized wind and thermal power,the influence of wind power integration on the transient power angle stability of power system was analyzed by using the extended equal area criterion method.Based on the analysis of the effects of various factors such as the different location of wind power integration,different proportions of wind-thermal power and reactive voltage control mode of wind power on the power system’s transient out-ofstep characteristics,the influence of multiple factors of wind power mentioned above on the oscillation center was analyzed.Finally,based on the actual grid of the first and second Northwest-Xinjiang AC grid interconnection transmission channels with large-scale wind power integrated and delivered,the optimal allocation recommendations of the separation device of transmission channels were analyzed and proposed.1)Based on the analysis of the influence of different proportions of wind-thermal power and positions of wind power integration on the oscillating center,the rules for optimizing the allocation position of the separation device were given.2)The effects of successive actions of the multi-channel decoupling device on power grid safety and wind power off-grid were analyzed after simulation,and optimization suggestions for multi-channel cascading split were proposed;3)For a long transmission channel composed of multiple sections of lines,the risk of wind power off-grid and secondary disturbances caused by the indiscriminate action of the disassembly devices of each section under the same conditions was simulated and analyzed.Measures for setting different values of the separation device in each segment to alleviate the wind power off-grid and improve the stability of the power grid were proposed.4)The simulation analyzed that the wind power may be disconnected from the power grid during the operation of the separation device due to the low wind power fault ride-through capability.The research proposed optimization measures for the fast out-of-step separation device with a predictive function for the allocation of the wind power transmission channel,which sped up the operation speed of the separation device and reduced the risk of wind power off-grid.