Power quality monitoring system is a unified monitoring and comprehensive analysis system for the measured points of power system. The power quality monitoring system is based on the communication network. The selection of communication network and protocol is very important for the compatibility and stability of the power quality monitoring system.

In the field of communication technology, both sides of communication need to abide by some established procedures when sending and receiving data to ensure the correct and reliable transmission of data. These procedures are referred to as communication protocols. After the communication protocol is formulated, the devices made by different manufacturers can access to the same system in theory.

The digital substation based on IEC61850 protocol has many different characteristics from the traditional substation. These characteristics have an important impact on the operation, maintenance and expansion of the digital substation.

With the rapid development of smart grid, as well as the increasing requirements of users for power quality, networking, informatization, standardization and intelligence become the inevitable trend of the development of power quality online monitoring device. At present, some power quality on-line monitoring manufacturers widely use custom communication protocols when realizing data communication, which leads to incompatibility between different manufacturers' equipment in a station, difficulty in resource sharing, low efficiency of monitoring platform and high cost of system monitoring.

Therefore, if the power quality on-line monitoring device wants to be installed in the power grid, it needs a unified IEC61850 communication protocol. IEC61850 standard standardizes the data naming, data definition, device behavior, device self description characteristics and general configuration language. It makes it possible for different intelligent electrical equipment to share and interoperate information.