Study On Transformer Differential Protection Based On Electronic Current Transducer

The characteristics of smart substation is ’intelligent equipment Secondary network equipment the device object modeling’. Replace CT with ECT and replace communication cables with optical cable communication in smart substation. In the present smart substations, the operating criterion and characteristic setting of transformer differential-protection are still using the traditional way without fully utilizing features of electronic transducers.The main studying contents of this paper are as follows:Basing on the advantages of electronic current transducer (ECT) and the setting regulation of traditional transformer differential-protection, this paper proposes an idea to improve protective performance by decreasing both threshold value and restraining curve slope. The new setting methods for three key parameters, pick-up current, start-restraint current and restraining curve slope, are described in detail. The paper proposes novel auxiliary criteria based on electronic current transducer (ECT). The auxiliary criteria adopts the ratio of the amplitude of current data from one terminal to the amplitude of the sum of the rest to judge system fault states.Construct a simulation system of different faults of power transformers in PSCAD. And model of ECT. The validity of the idea and the setting methods are verified by simulating different faults of power transformers. The theoretical analysis and simulation results indicate that the proposed updating criterion has higher sensitivity without losing reliability and improves sensitivity of transformer protection in turn-to-turn short circuit in power transformers.Preliminary, build the model of transformer protection device according to IEC61850standards.Each of transformer protection device function is taken as a logical node. According to algorithm realizing functions, choose data objects in logical nodes. Logical nodes are divided into different logical devices. Establish the whole information models and functions model services. The realization of model mapping is briefly introduced.