Journal of Solar Energy Research
Volume:6 Issue: 3, Summer 2021

In this paper, a new fast and accurate method for fault detection, location and classification on multi-terminal direct current (MTDC) distribution networks connected to solar distributed generation and loads presented. Some issues such as DC resources and loads expanding, and try to the power quality increasing have led to MTDC networks' development. It is important to recognize the fault type in order to continue service and prevent further damages. In this method, a circuit kit is connected to the network. Fault detection is performed with the measurement of the current of the connected kits and the traveling-waves of the fault current and applying it to a mathematical morphology filter, in the Fault time. Determine the type and location of faults using a mathematical morphology filter, circuit equations and current calculations. DC series and ground arc faults are considered as DC distribution network disturbances. The presented method was tested in a solar DC network connected to energy storages and solar resources with many faults. The results illustrate the validity of the proposed method. The main advantages of the proposed fault location and classification strategy are higher speed and accuracy than conventional approaches. The fault location error of the presented algorithm is less than 6.5 percent in the worst case. This method robustly operates to changing in sampling frequency [0.5-50 KHz], fault resistance [0.005-120 Ohm], and works very well in high impedance fault.

The study analyzes an integrated Magnesium-Chlorine Mg-Cl thermochemical cycle with solar parabolic trough system. Direct solar radiations have been estimated with tilted and tracking collectors in the Algerian desert. The results reveal that, tilted tracking axis aperture toward the south at local latitude angle is most efficient than does fixed tilted aperture facing south per local latitude angle with an average difference of 0,9 MWh/m2/year. Heat gain evolution from parabolic trough collectors is estimated to investigate heat sources. The best annual heat gain was observed in Tamanrasset with 7.919 and 19.99 MWh/m/year by fixed and tracking system, respectively. Hydrogen production rate from the process have been evaluated and compared under Algerian desert conditions. The maximum hydrogen production rate is obtained for Tamanrasset with 51,862 and 143,011 Ton H2/year by fixed and tracking system, respectively.

This article presents a method for the reduction of harmonics generated by photovoltaic the smart grid connected. Photovoltaic generators always produce harmonics due to the nature of the direct current they generate. In order to eliminate these harmonics, parallel active filters are used. They are based on seven-level inverters. For the extraction of maximum power produced by the photovoltaic generators, the modified perturb and observe algorithm is used. Furthermore, to reduce the distortions due to the injected continuous quantities, the filtering of the harmonic quantities is done by four levels active filters using three switching cells per arm connected downstream of the seven-level inverters. The proposed algorithm and the model of active filter are evaluated, by calculating of the total harmonic distortion of the current after filtering. The rate of 0.21% is obtained. Additionally, the simulation results show this rate is lower than that of the standard Institute of Electrical and Electronics Engineers norms. Besides, the performance of the algorithm has been demonstrated when the solar panels are subjected to variations in irradiance.

Solar power is a great potential of renewable energy to replace fossil fuel in the future. In recent years, new installed solar energy accounts for a very large proportion of the total renewable energy supplied to the load. However, the state of connecting large solar farms will affect the national power system stability and voltage quality in the local power system. Therefore, assessing impacts of solar farms on the power system is necessary to determine voltage stability, the limited capacity of solar power at each power system and the reliability of the power grid before and after solar power is installed. This study uses ETAP software to evaluate impacts of planned solar farms on the local power system in Hau Giang province in 2025. The simulation results show that the power system is stable in terms of power flow after solar farms operation, in which the system loss is significantly reduced. The voltages of the power system are not disturbed when the solar farms are available according to results of transient stability analysis. Power system reliability improves significantly after operating solar farms for specific loads. It is shown that SAIDI, SAIFI and CAIDI before and after solar farms are installed are 5,8524 and 4,9847 hours/customer/year respectively, 0,4134 and 0,3955 times/customer/year respectively and 14,157 and 12,602 hours/customer respectively. The results show that when 07 solar farms with total capacity of 265MW are put into operation, the solar farms have a positive impact on the power grid of Hau Giang province.

In this research, a single-phase multilevel inverter with a reduced number of switches and driver circuits is introduced for analysis in photovoltaic systems. The proposed multilevel inverter consists of two parts, basic circuit, and H-bridge, which are responsible for generating voltage levels and symmetry of voltage levels (positive and negative), respectively. The proposed basic circuit in this paper consists of six unidirectional switches and three input sources and doesn’t use any capacitors or diodes, which reduces the volume and complexity of the control system. In this paper, the seven-level proposed structure is simulated in the MATLAB/Simulink software and the utilized modulation to generate the output voltage levels is level shifted pulse width modulation. Moreover, photovoltaic systems are exploited to supply the proposed inverter’s input sources, which work with perturb and observe algorithm at the maximum power point. In the simulation section, the voltage, current, power waveforms of the photovoltaic system, and the voltage of the proposed inverter input sources are demonstrated, and the voltage and current waveforms of the inverter for different conditions such as radiation and modulation index change are given. Finally, to show the merits and features of the proposed topology, the inverter is compared with some recent symmetrical structures in terms of the number of components and the rated voltage of the switches.

In this study, the thermal performance of a tank-in-tank solar combisystem is dynamically simulated to investigate the effect of various parameters such as collector type and area, storage tank volume, building specifications, heat exchange terminal units, and climatic conditions on system performance. The results showed that by increasing the collector area, tank volume and thickness of wall insulation, the solar fraction increases. It was also found that the use of floor heating instead of a radiator system improves the system performance. The solar fraction using the evacuated tube solar collector is 2.3% higher than that using flat plate solar collector. The annual solar fraction of 45.6%, 63.4%, 41.2%, 34%, 57.3%, and 88.1% is obtained in Hot-Dry (Tehran), Hot-Dry (Yazd), Cold-Dry (Tabriz), Moderate-Humid (Rasht), Hot-semi Humid (Abadan), and Hot-Humid (Bandar Abbas), respectively. The environmental analysis indicates that using the proposed solar combisystem could save 2241.3 m³ natural gas and offsetting 4731.5 kg less CO2 emissions during a year. The life cycle cost analysis shows that the payback time of the proposed system for the economic conditions of Iran is 7 years.