Power quality refers to the quality of alternating current supplied to users through the public grid. Generally speaking, it refers to the power quality of grid lines. Power quality problems are mainly caused by the terminal load side. For example, the impact of reactive load will cause large fluctuations in grid voltage and reduce the quality of power supply.
With the development of power electronics technology, it not only brings positive aspects of energy conservation and energy conversion to modern industry, but also brings new and more serious damage to power quality due to the wide application of power electronic devices in all walks of life, and has become the main source of harmonic pollution of the power grid. Rectifiers, frequency converters, electric arc furnaces, electrified railways, and various types of power and electronic equipment are increasingly used in distribution networks for individual users in grid systems.
Affect or pollute the power grid. Cause voltage instability, overvoltage, harmonic generation, etc. Harmonics reduce the efficiency of power production, transmission and utilization, leading to overheating, vibration and noise in electrical equipment, aging of insulation, shortened service life, and even failure or burnout. Harmonics can also cause local parallel resonance or series resonance of the power system, so that the harmonic content is amplified, causing equipment such as capacitors to burn.
The nonlinear, impulsive and unbalanced power consumption characteristics of these loads cause serious pollution to the quality of the power supply. Therefore, eliminating the high harmonics in the power supply and distribution system is of very positive significance for improving power quality and ensuring the safety, stability and economic operation of the power system. On the other hand, the electrical equipment of modern industrial and commercial and residential users is more sensitive to power quality, which puts forward higher requirements for power supply quality. At present, harmonics, electromagnetic interference and reduced power factor have been listed as the three major hazards of the power system.
When the power quality of the power grid is disturbed or polluted and cannot meet the relevant standards of China's development, the technical level of power quality management of the power grid must be improved. In order to understand the actual working situation of power quality in the power grid, corresponding equipment is required for control and test data analysis, which requires the use of power quality analyzers.
