Wind Farm Collector Line Protection Research And Isolated Grid Operation Status Analysis

The shortage of fossil energy has promoted the rapid development of new energy,and the proportion of wind power in new energy power generation is also increasing.When a failure occurs in the collection line or output line of a wind farm,the electrical quantity cha-nge caused by the failure will impact the operation of the power system,and will also affec-t or even change the operating state of the Doubly fed Induction Generator(DFIG).Especi-ally after a fault occurs,due to the short-circuit characteristics of the DFIG and the multi-o-utlet and multi-branch wiring method of the current collection line,it will bring challenges to the traditional relay protection.At the same time,when a fault occurs and the wind farm is unplanned and Isolated Operation,because many of the faults are transient faults,it is im-possible to find the fault point,resulting in the lack of a basis for the wind farm to provide grid dispatching to re-connect to the grid.In response to the above problem-s,this article has done the following research:Describes the main components of DFIG,including Wind Turbines,Pitch Control Syst-em,Crowbar and Chopper protection circuits,grid-side converters(RSC)and machine-side converters(GSC),etc.,and establishes DFIG in a synchronous rotating coordinate system M-athematical model,and analyze the transient characteristics of DFIG when a fault occurs.According to the actual fault recording data and analysis report of the wind farm,When a failure occurs in the collection line or output line of a wind farm,the protection device in the wind farm will cause the unplanned isolated operation grid of the wind farm to cause th-e DFIG voltage to rise and exceed the DFIG overvoltage protection threshold.and current research has not paid attention to this phenomenon.According to the DFIG mathematical m-odel and transient characteristics to infer this phenomenon.If the protection in the DFIG does not operate,the terminal voltage will rise sharply and exceed the protection threshold.Even if the Chopper protection circuit is activated,the terminal voltage will also oscillate,It is possible to exceed the protection threshold.Combining the transient characteristics of the DFIG in the isolated operation after the failure of the collecting line,by comparing the oper-ating state of the DFIG under different conditions,the difference in the operating state of the DFIG is used to identify whether the fault on this line disappears after the unplanned iso-lated operation of the collecting line,this principle can be used as a basis for the restorati-on of grid connection of collection lines or wind farms.The idea of a transparent wind farm based on the Internet of things is proposed,combined with the analysis of the unplanned isolated network DFIG terminal voltage of the collection line caused by the fault,the fault line selection and the fault section scheme,and establishm-ent the construction has the output analysis of each DFIG,fault line selection and transpare-ent wind farm model with functions such as fault section and circuit breaker control,accor-ding to the needs of each node to achieve different functions and protection schemes with different priorities after a failure,is divided into three systems: master station,terminal,and edge,and proposes.Different devices with monitoring,protection,communication and othe-r functions are integrated into small and micro smart sensors to realize the collection and processing of various data,and the operation of each node to calculate and control the oper-ation of the transparent wind farm of the protection device.