The Electrolytic Rectifier For Grid Harmonic Monitoring And Fault Warning System

With the rapid development of the power electronic technology and various power electronic devices applied widely in power system, damage result from harmonic is more and more serious.People pay more and more attention to harmonic problems. The breakdown prewarning system for aluminum electrolyzation rectifying electric network plays an important role in security operations, which can monitor the change tendency of harmonic to reduce the rate of trouble by warning the operators.The basic conception, the cause and main harm of harmonic are introduced in this paper firstly. To take aluminum electrolyzation rectifying electric network in some Co., Ltd as the object of study, and its Structure and parameter is elaborated, and then it were analysed that the mechanism and character of harmonic produced by the main harmonic source—rectification device. It has set up the equivalent circuit of power supply network of rectification by the harmonic model of the power system component and drawn the harmonic impedance curve. The possibility of emergence of the resonance series connection and parallel connection to the rectification power supply network has been analysed in detail. It has improved the accuracy of power supply network prewarning with studying the early warning model of change tendency of harmonic containing rate of power supply network of rectification.Fianally the overall design scheme is formulated.On the basis of this research, it has developed the software system based on Windows 2000 OS with Delphi 7.0, and realized some modules such as the parameter of the power supply network setting module, resonance prewarning module, three phases imbalance prewarning, chang tendency of harmonic containing rate prewarning, etc., and provided the corresponding program diagram. The technique of the database, ADO, multhread and communication in the system is elaborated, and the codes and interfaces of some function module are provided. The question in the field debug is analyzed finally.This design idea and methods are worth of referring to the early warning system of other power supply network.