Develop The Experimental System Of Relay Protection Based On Virtual Instrument Technology

Relay protection simulating is an effective mean to learn and study its theory. In this paper, the existing computer protection experimental device in our school eletrical laboratory to protect the existence of many shortcomings, research and development of a teaching experiment based on virtul instrument technolog for relay protection system.The system integrated digital protection technology, power system digital simulation technology and virtual instrument technology, and virtual instrument software LabVIEW is effective combined with simulation software MATLAB, using PC in relay simulation design. MATLAB is used to simulate power system transient, which generates a variety of fault signals; and LabVIEW is used to develope a software protection device, which can perform the virtual simulation of dynamic and the visualize of action process on relay protection.In this paper, taking distance protection and transformer differential protection as examples, illustrates the process of realizing the relay experiment. Distance protection carries out the measuring impedance, which has operating characteristics of Polygon.The protection function is divided into signal measurement module, start module, fault phase selector module, and oscillation blocking module. Because power swings can be considered as a fault and causes relay trip, a new method based on the DC component of fault currents will be proposed to detect a fault during power swing blocking. Based on achieving transformer percentage differential protection, the transformer inrush current generation, characteristics and identification is studied. In addition, wavelet analysis is applied successive to the identification of magnetizing inrush current.Full using existing hardware and software resources, this system is rich in the protection of experimental function and teaching demonstration feature, which procides a record and analysis tool for testing dynamic performance of power system fault, relay protection and automatic equipment.It is very important practical significance in research and teaching power system protection.