Assesment of Power Quality Disturbances For Grid Integration of PV Power Plants

Abstract

Power Quality problems, which have become an important consumer issue in recent years, are defined as changes in voltage, current, or frequency in the power system. Among the factors affecting energy quality in grid-connected PV systems are island mode operation, current and voltage harmonics, transients, flicker, interruption, DC offset, notches, frequency changes, voltage sag / swell, voltage imbalances in the system and power factor. Because of the power quality problems, several transmission and distribution losses can occur due to both the consumers and the generators. Also, the integration of PV power plants to the main grid will cause several power quality problems, and a reliable operation of the grid with PV power plants is a significant issue for distributed generation. Thus, the first step in preparing a reliable algorithm for detecting power quality events occurring in the current grid is to model a power system in which power quality impairments can be analyzed. In this work, the power quality disturbances that occur in the low-voltage grid that is fed through both the main grid and the grid-connected PV system are modeled and investigated. Developed electric power distribution model includes simulation of voltage sags caused by three phase fault, transformer energization and asynchronous motor switching, voltage swells caused by three phase fault, transients due to large capacitor bank switching, harmonics and notches caused by the load connected via the power converter. Examination of the power quality disturbances with simulation clearly revealed the resulting waveforms, the response of the electrical power system to the fault conditions. Another advantage of the realized study is that the developed model can be used to measure the performance of the PV connected distributed generation system in fault detection and classification studies.