فهرست مطالب

Signal Processing and Renewable Energy
Volume:4 Issue: 3, Summer 2020

  • تاریخ انتشار: 1399/07/20
  • تعداد عناوین: 6
|
  • Majid Hosseinpour *, Mohammad Mohsen Rahimian, Navid Rasekh Pages 1-17
    As grid-connected Photovoltaic (PV) based inverters are being used more, these systems play a more important role in the electricity generation by distributed power generators. Power injection to the grid needs to meet predefined standards.In order to meet the harmonics requirement of standards, they need an output filter. The connection through an LCL filter offers certain advantages, but it also brings the disadvantage of having a resonance frequency.LCL filter can easily help the system to satisfy these requirements but also introduce a resonance peak which makes the system control a challenging task. In this paper, a three-level Neutral Point Clamped (NPC) inverter is connected to the grid through an LCL filter. The injected current of the inverter is controlled using Proportional-Resonant (PR) controllers. The resonant peak of the filter is also damped using capacitor current feedback. A systematic mathematical design procedure for controller and filter capacitor current feedback coefficients is investigated in details. Simulations are carried out in MATLAB/Simulink environment and results depict suitable performance of the system with designed parameters.
    Keywords: LCL filter, active damping, PR Controller, NPC Inverter
  • Ali Moghassemi, Shayan Ebrahimi, Javad Olamaei * Pages 19-39
    This paper reviews and compares the most important maximum power point tracking (MPPT) techniques used in photovoltaic systems. There is an abundance of techniques to enhance the efficiency of photovoltaic systems. The crucial distinctions between these techniques are digital or analog implementation, simplicity of the design, sensor requirements, convergence speed, stability, range of effectiveness and costs. Thus, opting for a suitable algorithm is vital as it affects the electrical efficiency of the PV system and lowers the costs by lessening the number of solar panels needed to get the desired power. Moreover, the paper provided a summary of the most used MPPT algorithms.
    Keywords: PV System, MPPT, Power, Speed, Efficiency
  • Saleh Ghorbani, Saeed Ghazi-Maghrebi * Pages 41-55
    In this paper, an asymptotic estimating technique to detect direct sequence spread spectrum (DSSS) signals using modified frequency domain fourth-order cumulant is proposed. Based on 2-D slices fourth-order cumulant, an efficient algorithm is proposed to solve the problem of complex computation and huge processing time. The method of fourth-order cumulant in frequency domain can achieve detection probability above 50% at SNR -25dB. In this paper, we strongly decrease processing time and complexity of computations that it makes this method appropriate for employing in the DSSS detection systems. This method only requires to store a row vector while ignoring all the low and diagonal elements and therefore the required memory is highly reduced.  In addition, as it uses two-line search strategies (predictor and corrector) to obtain a new iterative point, the spectral properties of the diagonal updating scheme is improved, and rapid convergence property is gained.  Also, this method estimates carrier frequency and symbol rate simultaneously in the online processing. Simulation results and computation analysis indicate that processing time of the proposed method is decreased about 30% with respect to the commonly used fourth-order cumulant methods.
    Keywords: DSSS signal, Frequency domain fourth-order cumulant method
  • Bahadour Mozafari, Ali Shahhoseini * Pages 57-65
    In the recent two decades, CdTe thin-film solar cells have been used due to their proper efficiency and low manufacturing cost. The transparent conducting oxide (TCO) applied in front of them has an important role in improving performance both optically and electrically. In this paper, we have used molybdenum trioxide (MoO3) as a TCO layer, and we also have done a comparison between this and other common TCO layers such as tin oxide (SnO2), zinc oxide (ZnO) and titanium dioxide (ZnO) and then examined solar cell parameters in each structure. Numerical simulations of aforesaid CdTe solar cell structures have been done employing SCAPS software. Results indicate the electrical and optical parameters of CdTe/CdS solar cell with a MoO3 TCO layer which has been improved compared with other structures so that the efficiency of it reaches to 14.72% .This value is 0.64%, 0.51%, and 0.1% higher than similar cells with transparent oxide layer SnO2, TiO2, and ZnO, respectively.
    Keywords: Cadmium telluride thin-film solar cell, Molybdenum trioxide, TCO, scaps
  • Ebadollah Amouzad Mahdiraji * Pages 67-80
    Optimal switching has been proposed as a tool to improve the utility of the electricity grid among researchers in the electricity industry. In fact, according to Kirchhoff's rules, the restriction of the transmission of power from one path entails restrictions on the power passing through the corresponding parallel paths. Thus, in some operating conditions, opening a transmission line reduces the parallel paths and constraints imposed and, consequently, improves the network operating conditions. The effects of micro switching on market power in the power system are discussed first. To this end, the competition boundary problem has been developed to consider micro-switching. In this problem, the application of linear-integer models obtained on test networks shows that micro-switching can affect market power in a power system. This effect is further enhanced by the increase in HHI. Also, this effect is even greater at high load levels. This indicates the undesirable effect of micro-grid switching on market power if used without regard to market power. The following is a model for optimizing the micro-network periodic switching as a tool for system deployment to reduce the periodic cost of network deployment considering the market power of the actors. The results show that the optimal periodic switching of the microprocessor can reduce the operating costs of the whole period by considering the market power of the actors. Also, it reduces the market power of the actors compared to the case of micro-grid switching.
    Keywords: switching, Market, Linear Optimization Problem, Equilibrium in Electricity Market
  • Hadi Razmi, Hasan Doagou-Mojarrad *, Javad Olamaei Pages 81-94
    In this paper, a comparative study of optimization algorithms for determining the optimal size of hybrid stand-alone power systems at the lowest total cost is proposed. In this regard, the performance of the components of hybrid power system including wind turbine, fuel cell, anaerobic reactor, reformer, electrolyzer and hydrogen tank has been studied and several different optimization algorithms are taken into account. The proposed method can meet the load demand using wind energy and biomass as an available energy resource. In the stand-alone power system, power produced by the wind turbine and fuel cell (fed by the reformer) are applied to the demand. When these generations are more than the demand, additional power is delivered to the electrolyzer. Otherwise, the hybrid system is fed by the hydrogen tanks. The proposed method has been tested in Kahnooj region located in the southeastern of Iran and the results of various optimization methods have been presented in order to determine the optimal size of the hybrid power system.
    Keywords: biomass, fuel cell, Hydrogen tank, Optimization methods, Wind turbine