Research And Application Of The 110kV Substation Online Harmonic Monitoring System

In recent years, with the increasing of nonlinear loads in the industry, the harmonic distortion in power systems are becoming increasingly serious. The harmonic will produce great harms; the grid voltage waveform distortion can cause power quality to decline, affect the safe and economic operation of the equipment, and increase the interference of the communication system. Meanwhile, the harmonic will affect electrical equipment, relay protection, automatic device, computer measurement and measuring instruments. At present, the internationally recognized harm of the grid is the harmonic"pollution". The two leading international academic organization of the electrical engineering filed - IEEE and IEC were prepared for power harmonic suppression standards, and revised several times. Therefore, the real-time online monitoring of power harmonic is of great significance.First, this article introduces the basic concepts of harmonic and present status, summarizes the national standards and international harmonic standards simply, and points out some problems in implementation of national standards.Second, with the increasing of the power electronic devices in recent years, this article analyzes the main harmonic sources and their hazards, and describes the harmonic generation mechanism.Thirdly, this article describes the harmonic analysis and harmonic monitoring methods, and provides a theoretical basis for the study and constructs of the harmonic line monitoring system.Finally, this article establishes an 110kV substation online harmonic Monitoring System, this system is installed at the 110kV substations, and achieves a real-time monitoring of the harmonic.