Intelligent Substation Station Domain Protection Research

Along with the development of information technology and the Internet, theSmart Grid has become the main focus of the Power Grid Reformation. In order tocotton with the grand environment of the Smart Grid, and to fully accomplish thePower Grid’s intelligent protection, the relaying protection distribution of thesubstation should be upgraded to an intelligent one. The intelligent substationmaintains a high level of information sharing, which provides a new thinking for thestudy of the improvement of the relay protection principle, performanceimprovement and new principles. However the present protection distribution forintelligent substations still mostly uses traditional relay protection devices,traditional principles and traditional criterions. Therefore it is an urgency to improvethe relay protection within the substation by taking advantages of the information-sharing of the intelligent substation.With researches and studies on the principles and operative technologies of theintelligent substation area protection, this paper dividedly present the main andbackup substation area protection algorithms based on current differential protectionprinciples.The main substation area protection is consisting of three parts, as determine themain protection area, improve the protection principles within the area, andsimulation. It divides the intelligent substation into areas first. By judging whethereach protection area is in braking or differential state, it locates the fault. Sincetransformers are in each area, the protection needs to take the influence ofmagnetizing inrush current into consideration. Therefore, it improves the currentdifferential protection of each protection area, and uses the revised differential currentto balance out the influence of the magnetizing rush current. It also eliminates thedelay caused by second harmonic restraint when internal fault occurs. At last, it is simulated to be reliable and feasible by the simulation software.Taking the advantages of intelligent substation information sharing, I provide inthis paper a new backup protection scheme based on current differential principles forintelligent substations. This scheme divides the substation into three protection areaswith different characteristics. As the wide area contains circuits, this schemeimproves the wide area current differential protection which contains circuitdifferential area to avoid the maloperation under the influence of capacitive current.Then with the shared information it constructs an integrated protection area for thesubstation, and accurately locates the fault component. At last, it is simulated to bereliable and feasible by the simulation software.