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Cascaded H-Bridge MLI and Three-Phase Cascaded VSI Topologies for Grid-Connected PV Systems with Distributed MPPT
摘要： Cascaded multilevel inverter topologies have received a great deal of attention for grid-connected PV systems. In this paper, three-cascaded multilevel inverter configurations are proposed for grid-connected PV applications. These are the three-phase cascaded H-bridge multilevel inverter topology, three-phase cascaded voltage-source inverter topology using inductors, and three-phase cascaded voltage-source inverter topology using coupled transformers. Distributed maximum power point tracking (MPPT) of PV modules using perturbation and observation algorithm is used for all presented topologies. In all presented configurations, each PV module is connected to one DC-DC isolated ?uk converter for best MPPT achievement. Simulation is achieved by using the SIMULINK environment. The simulation results show that the three proposed topologies function well in improving the grid’s power quality. The grid currents are kept in phase with the grid voltage to ensure unity power factor, and the THD of the grid currents are within the acceptable range. The proposed topologies are experimentally implemented in the lab, and the switching pulses are generated with the help of the MicroLabBox data acquisition system. Comparing the three topologies according to the number of switches, voltage, and current stresses on switches and THD of the generated voltages and grid currents and according to the efficiency has been achieved in this paper, both experimentally and by simulation. The simulation and experimental results and comparisons are presented to verify the proposed topologies’ effectiveness and reliability.
关键词： voltage-source inverter,power quality,distributed MPPT,cascaded multilevel inverter,grid-connected PV systems,H-bridge
更新于2025-09-23 15:22:29
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Islanding detection for grid connected photo-voltaic systems for excess generation and under generation
摘要： Islanding occurs mostly in wide areas. The Dc-link-voltage method gives the effective results when compared to the Under/over Fre- quency/Voltage method and Rate of Change of Frequency (ROCOF) method. This paper describes the islanding detection based on ob- servation of the DC-Link-Voltage Source Converter (VSC) and also proposes a method for detecting islanding for Grid-connected Photo- Voltaic system based on rise or fall of DC-Link-Voltage for excess generation and under generation conditions. The proposed technique is validated through experimental results.
关键词： Grid-Connected,PV systems,Islanding,Anti-islanding,DC-Link-Voltage
更新于2025-09-23 15:21:01
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Surface Dust and Aerosol Effects on the Performance of Grid-Connected Photovoltaic Systems
摘要： A large number of grid-connected Photovoltaic parks of di?erent scales have been operating worldwide for more than two decades. Systems’ performance varies with time, and an important factor that in?uences PV performance is dust and ambient aerosols. Dust accumulation has signi?cant e?ects depending the region, and—on the other hand—understanding the role of absorption or scattering in particular wavelengths from aerosols is a challenging task. This paper focuses on performance analysis of a grid-connected PV system in Central Greece, aiming to study these e?ects. The methodology of analysis follows three directions, namely, PR computations, use of mathematical model’s prediction as reference value, and normalized e?ciency calculation. These metrics are correlated with the levels of dust accumulation on PV panels’ surfaces and the ambient aerosol mass concentration. The results show that only heavily soiled surfaces have signi?cant impact on PV performance and, particularly, a decrease of 5.6%. On the other hand, light or medium soiling have negligible impact on PV performance. On the other hand, the impact of ambient aerosol concentration levels on PV e?ciency is more complex and requires further study. Aerosol scattering of di?erent wavelengths can possibly a?ect PV e?ciency, however, this fact may be related to the speci?c spectral response of PV cells.
关键词： aerosols,dust,grid-connected PV systems,performance analysis
更新于2025-09-19 17:13:59
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Investigations on Operational Characteristics of a PV Integrated Unbalance Distribution System for Energy Management Studies
摘要： Background: Integration of solar PV presents various challenges in the power system, one such challenge is the variation in operational characteristics of the distribution system. Method: Solar PVs are installed at the distribution networks which are unbalanced in nature due to unequal distribution of load in each phase. The operational characteristics of distribution feeder alter with the increasing level of PV penetration, which includes variation in voltage level, power flow direction, change in reactive power and power factor. Such situation causes the distribution network operators (DNO) to face unprecedented challenge to maintain the quality of power. Therefore, there is a crucial need to recognize and quantify the technical impact that solar PV may have on the operation of unbalance distribution system to ensure the good quality and reliability of supply. In this paper, an 11/0.433 kV realistic rural distribution feeder of Indian utility is modeled to investigate the impacts of PV integration on the operational characteristics. A reformulated 3-phase Newton-Raphson (N-R) power flow algorithm is used for the solar PV integrated unbalance distribution system. Results: The results show that there are drastic changes in branch current loading, neutral current, power losses and power flow direction after solar PV integration. It is also observed that there is huge variation in bus voltage level, which is controlled by line voltage regulators. Conclusion: Such investigations are necessary before PV integration to the distribution network, which would help the utility engineers for monitoring, energy management, and planning studies.
关键词： 3-phase unbalanced power flow,integration,3-phase Newton-Raphson (N-R),penetration,solar PV,Grid connected PV systems
更新于2025-09-09 09:28:46