Power quality and voltage profile analyses of high penetration grid-tied photovoltaics: A case study

Abstract

Installed Photovoltaic (PV) capacity across the smart distribution grid has been on the rise in order to reduce greenhouse gas emissions. However, under high penetration of PV, there could be potential impacts on the operation and planning of distribution networks. In order to evaluate the impacts of grid-tied PV, a case study on power quality and voltage profile analyses is conducted using a 1.1 MW AC grid-tied PV power plant located at Florida International University. As part of the power quality analysis, study explores Total Harmonic Distortion (THD) and high power and high energy ramp rate analysis. Current THD is posed to trigger problems when generation is highly intermittent wherein Voltage THD does not have a tight relationship with power output. For voltage profile analysis, the case study considers peak and minimum daytime load scenarios under different levels of penetration, including the existing level, and appraises the plant's current and potential impacts in steady-state and time-series scenarios. The effect of using smart inverters with grid-support functions is also simulated. Results show that some major problems like voltage deviations and feeder losses can be expected at 60% PV penetration in minimum daytime load. The number of switching operations for voltage regulators also increase when smart inverters operate at Volt/VAr control mode. Results of the case study are discussed to highlight the significance of these issues in high penetration scenarios.