With the rapid development of industry, users have higher and higher requirements for power quality. The use of a large number of power electronic devices leads to the deterioration of power quality. Power quality has become the focus of power departments and power users.

Power quality is directly related to the power supply safety and quality of power system. Technically, the factors affecting power quality mainly include three aspects:

1. Factors of natural phenomena, such as lightning strike, storm, rain and snow, have an impact on power quality, causing power grid accidents and reducing power supply reliability.

2. The factors of automatic protection and normal operation of power equipment and devices, such as the impact of startup and shutdown of large power equipment, tripping and reclosing of automatic switch on power quality, resulting in temporary reduction of rated voltage, fluctuation and flicker, etc.

3. A large number of factors such as nonlinear load and impact load of power users, such as the impact of steelmaking electric arc furnace and electrified locomotive operation on power quality, cause a large number of harmonic interference, voltage interference, voltage fluctuation and flicker in the public power grid. In real life, it is mainly because the faults of power system and power components have a direct impact on power quality.

Therefore, the power quality monitoring should adopt the on-line monitoring method, that is, continuously collect, record and store the steady-state information such as frequency deviation, voltage deviation, voltage fluctuation and flicker, harmonic, three-phase imbalance and transient information such as voltage drop, voltage surge and voltage interruption. Strive to measure the power quality of power system grid in real time and accurately, analyze the causes of power quality problems, and take technical measures to improve the power quality of power system grid in time.

The power quality online monitoring system can realize the online monitoring of power, analyze and process the collected data, and generate various power and power quality reports, analysis curves, graphics, etc.