Research on Voltage Detection Method of UPQC Based on NF-FLL

Unified power quality controller, as a comprehensive power quality control equipment, can effectively control the power quality of distribution network. In order to solve the problem of frequency fluctuation and multiple zero crossing of voltage in traditional synchronous reference system of UPQC, UPQC integrated Photovoltaic-battery energy storage system (PV-BESS) can make comprehensive governance of power grid. The PV-BESS unit ensures uninterrupted power supply to the system under extreme conditions. Notch filter-based phase-locked loop (NF-PLL) based on notch filter was proposed, and an improved voltage detection method based on notch filter phase locked loop (NF-PLL) was proposed. The UPQC simulation platform was built, and the simulation verification was carried out under two conditions of three-phase voltage distortion and voltage sag. The simulation results showed that the proposed voltage detection method can detect and compensate the voltage sag effectively and quickly.