Power quality online monitoring system can provide basis for power system to solve power quality problems. From the perspective of users, power quality refers to all abnormal disturbances of power supply voltage, current and frequency that will cause abnormal operation, failure or power failure of electrical equipment. In recent years, rectifiers, frequency conversion and speed regulation devices, electric arc furnaces, electrified railways and various power electronic equipment in the distribution network are increasing. The nonlinear, impulsive and unbalanced power consumption characteristics of these loads cause serious pollution to the power quality.

The power quality online monitoring system can realize the comprehensive online monitoring, statistics, analysis and evaluation of various power quality information, provide the monitoring of system voltage, current, frequency, power, power factor, electric quantity and other data, and provide the functions of full electric quantity out of limit alarm and fault filtering; The total electric quantity data is saved to the local file or database at the same time, and can be called out at any time for trend analysis.

The on-line power quality monitoring device records the voltage level information and its duration when the instant occurs, and provides transient voltage waveform analysis. Online record the data information of each phase voltage and current during each voltage disturbance, and provide the waveform analysis of each phase current and voltage during voltage disturbance, as well as the trend curve analysis of voltage change.