The Research On System Relay Protection For Wind Power Integration Based On Power Flow Transfer Distinguishing

The wind power is a random,intermittent and uncontrollable energy source,the large-scale connection of wind farms with power grid has adverse effect on the safety of power system.There are plenty of high-quality wind energy resources in three northern regions and south-east coastal region in china,which is far away from load center,with the development of “the global energy interconnection”,the way of wind power base Centralized combined to the grid is more widely used.This style has the characteristics of high concentration,weak power grid and long distance,With random variability of the wind power,The probability of cascading trips caused by power flow transfer factor after fault will be increased.It is urgent to study the relay protection with the perspective of system science.A integrated protection and control method is presented from the system viewpoint,which identify a heavy loading power line with a fault under wind power flow fluctuation,determine that the fault line is tripped by protection operation,and the power flow is transferred from the fault line to sound lines,which will lead to over load in sound lines.The potential loading capability of lines will be exploited under safety prerequisite with adaptive over load protection.Emergency control is used together to curtail wind power according to field conditions,and eliminate over loading in sound lines,which will prevent cascading failure of grid.finally,the correctness of the proposed system protection scheme is verified.Firstly,this study analyzes the dynamic complex transition of power flow,study the method of distinguishing "asymmetric power flow transfer " based on local information such of voltage and current.This method has the characteristics of faster decision and no communication required,with system oscillation,developing and evolved fault have been considered,which solve the difficulty of wide-area backup protection such as the real-time requirement,a large amount of calculation,the determine complexity of protection scope.Secondly,this study puts forward a scheme of integration the wind power emergency adjustment and the relay protection on condition that the "asymmetric power flow transfer" has to be distinguished,which will protect the equipment under the premise of ensuring the stability of the system by calculating the load and load time of the line.Different from traditional protection,the protection will protect the system and the equipment together..Different from the traditional wide-area backup protection,theprotection will determine with local information.Thirdly this study presents a kind of adaptive overload protection method based on neural network.The temperature prediction scheme based on monitoring data of the substations and the lines together was put put forward.The high precision of short-time temperature forecast will be implemented by the training of online data based on Echo State Network.It will race against time for security emergency control by modify the relay protection setting value based on the calculation of the potential loading capability of lines.This study can solve the application difficult of the Line Rating Protection in Relay protection which caused by the requirement of rapidity and the distinguishing between overload and fault.In the end,protection devices are constructed to provide back-up protection for all or part electrical equipment of station territory.It verified that the protection can recognize correctly and act reliability in any case.