Impact of power quality on PV performance of grid connected systems

Abstract: The problem with the implementation of the PV generators is that majority of the UNDP offices are in developing and underdeveloped countries. Majority of these countries experience various problems with the power quality from the national electrical grid. There is also a second problem with the installed PV system, the problem is that the installed PV sources show a significant decrease in the expected annual yield ranging from 10 % – 60 % in some cases. The main aim of this thesis is to analyze the power quality in three countries (Nepal, Sao Tome and Namibia) and find the correlation between power quality and PV generation. This aim is done in five steps. The first step is the collection of measured data from the grid for a specific period of one year from July 2020 to August 2021. The collected data includes the current, voltage, power factor, frequency, reactive and active power. To achieve this, the Acuvim II power quality analyzer was sent to these three countries. In the second step, a literature review is done to research about power quality problems, identifying the power quality problems and analyzing the problems created by these identified power quality problems. In the three countries, undervoltage, overvoltage, swells, and sags where the main power quality problems which were recorded. The third step is a system case study process in which an in-depth analysis is done on the three PV systems and a simulation is done to understand the solar parameters which includes the specific yield, and performance ratio. The fourth step involves comparing the collected data from the PQ analyzer with the simulation results and determine the effects the power quality problems and system design have on the low annual yield. Also, the yearly amount of overvoltage and undervoltage in the three countries within the analysis period was analyzed. The voltage and fluctuation analysis also includes other power quality parameters which were measured. The collected parameters were analyzed and the correlation between the electrical grid requirements in the three countries were made with the recorded data. The final step involves recommending improvements and optimization techniques for the three systems to improve life cycle cost and long-term vision. Thus, analyzed results and simulated results are compared to evaluate the performance. The PV system in Namibia had the best grid conditions with all the grid parameters operating within the defined grid limits, there was a 30 % reduction in annual energy production in the Nepal system due to poor power quality conditions which included overvoltage, undervoltage, and frequency deviations. There was also a 50 % energy loss in the annual production of the PV systeminstalled in Sao Tome. Sao Tome also had the highest number of recorded outages with an average of 6 – 7 hours of outages recorded daily. Power quality problems recorded in Sao Tome included voltage fluctuation problems and frequency deviations.