Research On The Scheme Of Overcurrent Protection For Distribution Lines With Distributed Generation

A large number of distributed new energy access to the distribution network to ease the users' demand for power supply,but it also affects the power flow and current size of distribution network.And it will affect the reliability of the overcurrent protection of the original distribution lines.Therefore,the influence of distributed power supply on the over-current protection of distribution line is analyzed in this paper,on the basis of this effect,the overcurrent protection scheme is studied.The distributed generation supply access is divided into three parts by the access point:the upstream,the downstream and the adjacent lines.When the fault occurs in the three parts,the influence of the overcurrent protection of distribution line is analyzed and simulated respectively.And the result shows that with the increase of distributed power supply,it will cause the upstream protection losing of direction and the downstream protection losing selectivity.In this paper,a method for configuring the upstream and downstream protection of distributed generation access is presented.The upstream quick break protection is configured as an adaptive quick break protection,the action criterion of protection is structured by two phase current difference and line voltage method,and this criterion is not affected by fault type.The two sets of setting value protection method is used in the downstream,and which protection is used determined by detecting the switching state of the distributed power access.In addition,the integrated protection scheme of distribution system with distributed generation is studied and the trip logic is given.It can be seen from the analysis that the scheme can protect the distributed power supply system.Using PSCAD simulation and MATLAB programming method,the simulation of the overcurrent protection scheme for distribution lines with distributed power supply is carried out.The results show that under the situation of different distributed power supply capacity,when the distributed generation supply access point of the upstream occur faults or downstream occur faults,the established overcurrent protection scheme can reliably act,proving the correctness of the protection program.