Research On Adaptive Overcurrent Protection Of Distribution Network With Microturbine Source

Distributed Generation(DG)access to distribution network has a negative impact on relay protection.Taking micro-turbine power supply as the key point,this paper studies the adverse effects of grid-connected operation of distributed generation on overcurrent protection of distribution lines,and puts forward some countermeasures.Thereby ensuring the normal operation of the relay protection system and ensuring the safety and stability of the power grid.In this paper,the influence of distributed generation on the overcurrent protection is discussed.The simulation models of wind power,photovoltaic,micro turbine and other types of distributed generators are established,and their short-circuit current characteristics are analyzed.On the basis of analyzing the traditional overcurrent protection principle,a simulation model of overcurrent protection is established.Based on the theoretical analysis and simulation analysis of the influence of the distribution network with different position and output power on over current protection,it is concluded that the distributed power access may lead to the expansion of the protection range of over current protection devices,resulting in the emergence of the superior protection without selective tripping and the error of the current level protection..In view of these effects,on the basis of analyzing the short circuit current of different fault types,the action criterion of adaptive overcurrent protection is obtained.The criterion is considered as the adaptive calculation value of the system equivalent impedance.By setting up an adaptive overcurrent protection simulation model,the adaptive over current protection in various conditions,such as the location of the fault point,the output power of the distributed power supply and the action characteristics of the adjacent line faults,is analyzed.It is proved that the adaptive overcurrent protection can effectively solve the shadow of the over current protection of the distributed power supply.