Research On Protection Scheme Of Intelligent Distributed Distribution Network

With the increasing improvement of distributed generation technology,more distributed generation(Distributed Generation)has been accessed to the distribution network,transforming the distribution network from a single power network to a multiple network,and changing the trend direction from one-way flow to two-way flow.The access of distributed power supply inevitably affects the topology of the original distribution network,causing problems such as difficult to adjust voltage,island operation,and low voltage crossing,and affects the normal operation of the original relay protection device of the distribution network.For this reason,aiming at all kinds of faults in the distribution network with distributed power,this paper analyzes the distribution network protection scheme based on the coordination of zone longitudinal connection and three-level protection,and selects a section of grid data of Shandong power grid to apply the protection scheme to a company in the 1000 volt A station,and compared with the plan to implement a similar trip analysis of similar failures,to achieve its practical application in the protection of distribution networks containing DG.Firstly,this paper analyzes the current situation and impact of the protection of the distributed generation network scheme.The access of distributed power supply will cause the power direction of distribution network to change,which will increase and divert the line protection.Through analyzing the advantages and disadvantages of various protection schemes,and deeply discussing the impact of the introduction of distributed power supply on distribution network,it provides a realistic basis for fault location and distribution network protection schemes.Secondly,based on the combination of partition vertical link and tertiary protection.,this paper proposes a single network protection scheme.According to the different installation locations of distributed power supply,the distribution network area is divided.The distributed power supply upstream area adopts directional longitudinal protection,and the partition longitudinal protection uses the directional discriminant element to recognize the power flow,and realizes the fault location through the logical judgment of the electrical quantity for send accurate action signals and complete the fault removal.The tertiary protection is to select three fixed-position switches in all distribution network switches as qualifying circuit breakers,branch circuit breakers,and demarcation circuit breakers,to clarify the relationship between the upper and lower levels,to discard the switch with an unclear position,and to cancel its trip function.The distribution line will be properly dismantled into three parts: trunk line,branch line,and user,so as to achieve "user failure does not go out,branch failure does not enter the station",so as to achieve the precise location of the fault and minimize the power outage range.Finally,In this paper,the actual data of Shandong Power Grid is selected to solve the problem of difficult distribution network fault location according to the principle of distributed longitudinal connection and three-level protection.The relay protection fixed value is determined by relay protection fixed value calculation.Finally,the adaptability of zone longitudinal connection and tertiary protection is verified by comparing the actual faults of a power supply company before and after the transformation of a 10 V line.