Roohollah Fadaeinedjad

Temperature of a photovoltaic module under the influence of different environmental conditions – experimental investigation

The climate changes affect photovoltaic (PV) module temperature significantly. The module temperature is one of the most important factors that influence the PV module efficiency and a deep analysis of PV module temperature will aid in better understanding of the environmental influences on the PV module performance. The module temperature depends on many parameters such as solar radiation, ambient temperature, air humidity, speed and direction of the wind, PV module orientation, dust and sand deposition on PV module, and PV module materials. An experimental research was conducted to investigate the effect of these factors on the PV module temperature in the Renewable Energy Laboratory of the Graduate University of Advanced Technology in Iran. The results of this study highlighted that the deposited dust over the PV module surface increases the module temperature and this consequently decreases the PV module power. It was also revealed that a combination of the temperature increase and the incident solar radiation decrease due to the dust deposition over the PV module enhances significantly the module power reduction.

Resolving Power Quality Issues Raised by Aerodynamic Aspects of Wind Turbine in Isolated Microgrids Using Fuel Cell/Electrolyzer System

This paper shows how the power quality issues can be resolved in wind-diesel microgrids by means of a fuel cell/electrolyzer (FC/ELZ) system. In this regard, an autonomous hybrid power system, including a diesel generator and a fixed-speed wind turbine (FSWT) equipped with a FC/ELZ system, has been investigated. The main aim of employing the FC/ELZ system is to reduce fuel consumption and mitigate the aerodynamic effects of wind turbine (i.e., tower shadow, wind shears, yaw error, and turbulence) on power quality in the microgrid. To conduct a comprehensive study, the detailed models of the devices are used. The aerodynamic and mechanical aspects of WT are simulated using AeroDyn and FAST, and the thermodynamic and electrochemical aspects of FC/ELZ are simulated using models validated by experimental data. Furthermore, control of power electronic interfaces for the FC/ELZ system, including a bidirectional dc/ac voltage source converter (VSC), a dc/dc converter to boost the FC output voltage, and a dc/dc converter to reduce input voltage to the ELZ, is presented. The studied system was implemented in a MATLAB/Simulink software environment. The simulation results demonstrate the efficacy of the FC/ELZ system in reducing the flicker level and suppressing the voltage fluctuations induced by yaw error and turbulence.

An investigation of furl control in a direct-drive PMSG wind turbine

In order to fully study various phenomena related to small wind turbines (WTs) in wind energy conversion systems (WECSs), a comprehensive model that considers their mechanical, electrical and aerodynamic aspects is needed. One such phenomenon is furl, which is a mechanical mechanism that protects small horizontal axis wind turbines (HAWT) against excess speed and power. In this paper, a new detailed model for a small permanent magnet synchronous generator (PMSG) based WT with furling control is developed. The system under study is a variable speed WT/ PMSG configuration that uses back to back voltage source IGBT converters to connect to the grid network. For the model, software such as TurbSim and FAST was used to model a wind profile and the mechanical parts of the WT and Simulink/MATLAB was used to model the WT generator and electrical controllers; the voltage source converters (VSCs) were operated with a field oriented control (FOC) method. Simulation results that show the performance of the small WT with furling control under different environmental and network conditions are presented.

Generator Coherency and Network Partitioning for Dynamic Equivalencing Using Subtractive Clustering Algorithm

In this paper, a new method called subtractive clustering is presented to partition a power system into areas after a disturbance occurs. Subtractive clustering is basically used as a preprocessing step for other clustering methods to overcome their shortcomings, such as the need to predefine the number of areas and high dependency to random functions. However, due to the special characteristics of power systems, this method itself can be used to find areas. In subtractive method, the degree of coherency between all buses is used to form a density value for each bus. To calculate the degree of coherency between buses, the frequency components existing in the angular velocity variation of voltage phasors, in the range of interarea and local oscillation modes, are extracted. Then, the correlation between the real parts of these frequencies and the correlation between the imaginary parts are calculated individually. This means that the coherency between each pair of buses is assessed in two dimensions, which results in more efficient dynamic coherency identification. The capability of the proposed method is demonstrated for disturbances applied on the 16-machine, 68-bus system. It is observed that subtractive method is highly appropriate to find coherent areas for different disturbances.

Optimal placement and sizing of PV systems and electric parking lots considering reactive power capability and load variation

ABSTRACT Power systems should operate in reliable, stable, and efficient conditions. Addition of new generation units or loads to the power systems may change their performance. Therefore, appropriate decisions should be made to manage these elements to improve the power system performance. In this study, optimal placement and sizing of photovoltaic systems and electric parking lots (EPLs) are studied considering the reactive power capability of the inverters and load variation in a 24-h period. For the EPL, a proper charge/discharge scheme (CDS) is initially proposed to flatten the daily load profile; then the EPL with the associated CDS is considered to find its optimal location. Voltage profile, energy losses, bus, and line voltage stability are considered as the objectives of the problem. Genetic algorithm and backward–forward power flow method are utilised to solve the problem considering the IEEE 33-bus system. The results show that all objectives are improved utilising the proposed method.

A Remedy for Mitigating Voltage Fluctuations in Small Remote Wind-Diesel Systems Using Network Theory Concepts

This paper presents a practical solution to the voltage fluctuation problem, induced by the aerodynamic aspects of wind turbines (WTs) (viz., wind turbulence, yaw error, wind shears, and tower shadow), of small wind-diesel systems. It utilizes some network theory concepts to develop a decentralized control scheme for improving the system voltage profile without any communication link. In the proposed scheme, the voltage-control-point(s) of diesel-generator(s) (DGs) is properly chosen to maintain the system voltage variations within an acceptable limit. For this purpose, a supplementary control signal is applied to the automatic voltage regulator of DGs. The proposed technique is able to satisfactory regulate the bus voltages over wind speed variations, in as much as the simulation results obtained from several study systems have validated it. Moreover, a frequency regulation scheme is presented to share the active power, not supplied by the wind power, among DGs with the aim of reducing the total fuel consumption of the DGs set. To this end, the governor characteristics of DGs are coordinated by adding two adaptive gains, corresponding to the DG output power, to the speed control system. The type-1 WT is considered for the study since its impact on the system power quality is the worst, and three software packages, including TurbSim, FAST, and Simulink are used to comprehensively model it.

Optimum slope angles and the corresponding uncertainties for a solar collector

Determination of the optimum slope angle of a solar collector is highly dependent on the incident solar radiations on the collector surface. As collected instantaneous data of incident solar radiation values are averaged, more attention must be directed towards these figures by determining the uncertainties in these measurements as this allows the calculation of the optimum slope angle. These average solar radiations give a definite optimum slope angle if they come along with the lowest uncertainties. Hence, this study aimed to find the optimum slope angles of solar collectors with corresponding uncertainties. For doing this, the solar radiation data borrowed from the Iranian Meteorological Organization which were measured on a horizontal surface in a period of 20 years (1986–2005), were employed. The results showed that the uncertainties of the optimum slope angles in some cities were quite high and it indicated that in this case more attention should be paid to select the appropriate optimum slope angle. These changes were more in cold regions compared to hot and dry regions because the weather in the colder climates is typically more transient than the weather in hot and dry climates.