Power Quality Analysis for Photovoltaic System Considering Unbalanced Voltage

摘要

Background/Objectives: Voltage unbalance is one of the most important power quality problems in distribution network. In this way, three phase Photo Voltaic (PV) system can increase voltage unbalance. Methods/Statistical Analysis: In this paper a three phase photovoltaic system with Maximum Power Point Tracking (MPPT) has been installed in an unbalance distribution network due to reduce Voltage Unbalance Factor (VUF). Also, a Dynamic Voltage Regulator (DVR) has been used to get better outcomes. Results: Results show that in the case in which load is balance and only network is unbalance, the system comprised of PV, MPPT and DVR can diminish VUF by 10%. Moreover, THD analysis is done and is obtained around 2.27%. This system is modeled in MATLAB/ SIMULINK. Conclusion/Application: Considering the benefits of using PV system for sustainable energy, utilizing MPPT and DVR can lessen voltage unbalance in distribution networks inclusive photovoltaic systems. First, output voltage waveform of three-phase photovoltaic system simulated in this paper with regard to existing controlling structure in PV system is balanced to radiation change (500 –1000W/m2) in a good approximation and acts like a balanced three-phase source. Second, when this photovoltaic system approaches an unbalanced load which is located in an unbalanced network, the voltage imbalance decreases in that bus. Also when PV system gets further from the considered load, the impact of voltage imbalance reduction decreases in that load and also whatever the used photovoltaic system in the network is nearer to a special load, the imbalance compensating effect becomes more sensible. Also according to the performed simulations if there is a load which is sensible to the imposed voltage imbalance from network, PV-DVR system can be used for modify the observed voltage imbalance from network. It is worth noting that the PV-DVR system hasn’t the ability to modify observed imbalance from network due to imbalance load. PV-DVR system in this paper has the ability to compensate voltage imbalance up to 10% and for more, the capabilities of both photovoltaic system and DVR must be added. In addition, or proposed network, FFT analysis is done. Therefore harmonic load flow illustrates the suggested photovoltaic system using PV-DVR is acceptable from harmonic distortion point of view. THD is obtained around 2.27% that is good value for PV-DVR system in comparison with 5% allowable standard value.