With the rapid development of the national economy and the initial formation of the electricity market, power quality has attracted high attention from the power sector. In order to take reasonable measures to improve power quality, establishPower quality monitoring仪The analysis system requires correct detection, evaluation, and classification of power quality. On the one hand, impulsive and nonlinear loads can lead to serious power quality problems such as waveform distortion, voltage sags, and voltage flicker.

On the other hand, users are using increasingly complex electronic devices that are sensitive to power quality and require high-quality and reliable power. Nowadays, power producers, power suppliers, and power users are increasingly valuing power quality. In industrialized countries, power quality testing has become a very important issue. Power quality monitoring is an important link in solving power quality problems and is the foundation for achieving power quality analysis. In order to accurately reflect the power quality information of the power system, online monitoring methods have been widely used both domestically and internationally to more effectively monitor power quality.

There are many detection methods for power quality problems, which can be divided into steady-state power quality problems and dynamic power quality problems based on their generation time and duration. The characteristics of steady-state power quality problems are waveform distortion, long duration, and abnormal power quality over a period of time, mainly including overvoltage, undervoltage, voltage imbalance, harmonics, and frequency offset. The characteristics of dynamic power quality problems are transient duration, including pulse transient and oscillation transient, mainly including voltage surge, drop, voltage transient, and voltage flicker.

Amplitude, frequency, and phase angle are the three basic parameters that describe a standard sinusoidal quantity. Due to the presence of many sine waves of different frequencies in the power grid, the power waveform is distorted. The power system adopts three-phase power supply. If the three-phase load is unbalanced, it will cause three-phase electrical power imbalance. So the indicators for measuring power quality can be considered from four perspectives: amplitude, frequency and waveform, and three-phase balance.