Networking, informatization, standardization and intellectualization have become the inevitable development trend of power quality online monitoring system, especially with the promotion and construction of intelligent substation, the introduction of IEC61850 standard into the development of power quality online monitoring device has become an inevitable trend.

The power quality online monitoring device mainly monitors the line according to the relevant requirements of national standards. According to the requirements of national standard and actual power system, the power quality monitoring device mainly includes the following indicators: allowable deviation of power supply voltage, voltage fluctuation and flicker, three-phase voltage imbalance, power grid harmonics, etc.

The power quality data module displays the real-time data of power quality with graphical interface, queries the historical data of specified power quality monitoring interval and time from historical database, and displays all historical data inquired by military service table or curve. The real-time data is obtained and sent to the monitoring center according to IEC61850.

At present, there are power quality on-line monitoring manufacturers' custom communication protocols, and the standards they follow are different, which leads to the problems of poor compatibility between different manufacturers' equipment, difficulty in data sharing and low efficiency of monitoring system platform in the construction of monitoring network. Therefore, the IEC 61850 standard, unified communication protocol, will appear. For the power quality monitoring equipment which can not meet the IEC61850 standard, the IEC61850 protocol converter can also be installed to meet the requirements.