In the process of using new energy to generate electricity, improving power quality is one of the important work of power grid construction, which plays a key role in the management and analysis of power system operation state. In improving power quality, people pay more and more attention to the continuous analysis and monitoring of power system.

Photovoltaic power station is mainly composed of photovoltaic cell array, photovoltaic combiner box, inverter and substation. Photovoltaic power generation will affect the power quality of power grid, and will cause voltage and reactive power problems, harmonic problems, DC deviation problems and so on.

First of all, it is necessary to install power quality on-line monitoring device to monitor the power quality changes of the whole power grid. The power quality on-line monitoring device adopts high-speed and high-performance dual core processor, which integrates harmonic analysis, flicker measurement, power measurement, imbalance measurement, fault recording, event recording and other functions. It records steady-state data and transient data, and excavates each bureau in deep level The cause of the incident. Fast collection and accurate analysis of various power parameters, monitoring and evaluation of power quality indicators. The power quality monitoring and management system is composed of abundant communication interfaces, flexible communication forms and powerful background software.

Aiming at the problem of harmonic in power grid, active filter is adopted to suppress harmonic. Active filter controls current generator to generate a precise load harmonic current according to the harmonic content of load current measured by current transformer, and feeds back to power supply in the next cycle, so as to reduce the amplitude of harmonic current.