DETERMINING APPROPRIATE SIZE AND CONTROL MODE OF PV GENERATION IN DISTRIBUTION SYSTEMS CONSIDERING VOLTAGE STABILITY

Abstract

Since PV generation starts to play a vital role in distribution networks, the requirement to assess the effect of this type of renewable energy source on the system voltage stability becomes important. In this research, the PV modules model based on the single-diode five-parameter model considering environmental conditions is used. Then, the output power from PV is generated every time-step throughout a pre-defined duration, along with the load data using different types of time-varying load models. At each time-step, the steady-state operation of the system is analyzed by AC Power Flow calculation. From the results of the Power Flow analysis, the general PQ Voltage Stability Index (PQVSI) can be determined to indicate how close the system’s current operating condition to the voltage instability condition. Using this index as a main criterion, this research shows how to specify the appropriate location, size, as well as control mode of the PV farm. In addition, the other criteria including system power losses and voltage deviation are also taken into consideration in the process of PV design and installation to fulfil the study. These supplementary criteria are represented by a common index named Multiobjective Index (MOI). Furthermore, this research also demonstrates the benefit of operating the PV generation system at the power factor less than unity. Utilizing a real distribution network in Thailand, this research will clarify the simulation results to confirm the validity of the methodology. The research is also expanded to satisfy various case-studies such as voltage control mode and scattered PV units.