Research Articles
Power systems
mohammadreza sheibani; abbas ketabi; mostafa nosratabadi
Abstract
Harmonic state estimation (HSE) is the process of assigning a value to an unknown system state harmonic variable based on measurements from that system according to some criteria. Determining the best harmonic meters places in the system helps to increase the accuracy of the HSE. In this paper, a methodology ...
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Harmonic state estimation (HSE) is the process of assigning a value to an unknown system state harmonic variable based on measurements from that system according to some criteria. Determining the best harmonic meters places in the system helps to increase the accuracy of the HSE. In this paper, a methodology is presented for optimal placement of power quality (PQ) meters in a power system. The PQ meters results are used to estimate the unknown harmonic variables. Mean square errors of estimated total harmonic distortions in normal condition is selected as the cost function, while single line and meter loss contingencies are also considered by formulating a multi-objective optimization exercise. To achieve this, seeker optimization algorithm (SOA) based on Pareto optimum method has been proposed here. Simulation are performed on an IEEE 14-bus test system. The simulation results demonstrate the effectiveness of the proposed methodology for harmonic state estimation and optimal meter placement.
Research Articles
Industrial Electronics
Farzad Sedaghati; Naser Hashemipour
Abstract
This paper proposes a multilevel inverter that produces many steps in output voltage using fewer power electronic switches. The configuration of the proposed inverter is modular and extendable. The suggested topology consists of a combination of series-connected switching units and a conventional H-bridge ...
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This paper proposes a multilevel inverter that produces many steps in output voltage using fewer power electronic switches. The configuration of the proposed inverter is modular and extendable. The suggested topology consists of a combination of series-connected switching units and a conventional H-bridge converter. The presented multilevel inverter is analyzed in both symmetric and asymmetric configurations. Two different methods to determine the size of DC voltage sources of the asymmetric configurations are presented to achieve the maximum steps in the output voltage. The characteristics of both symmetric and asymmetric configurations are given and compared together in detail. {#R1-2}The comparison results show that the asymmetric configuration with second design method uses less power switches and has less power losses than symmetric and first design method asymmetric configurations. However, it has more (Total Voltage Rating) TVR than two others. The comparison between symmetric configuration of the proposed multilevel inverter and four similar multilevel inverters shows that the proposed inverter uses fewer power switches and has less power losses. Finally, a laboratory prototype of the multilevel inverter is implemented and the experimental measurement results are given. The experimental measurement results validate proper operation of the proposed multilevel inverter.
Research Articles
Control
Mir Mohammad Khalilipour; Farhad Shahraki; Jafar Sadeghi; kiyanoosh Razzaghi
Abstract
The paper presents the computer simulation of a multivariate control algorithm. Industrial relevance is given as the problem is derived from a real plant, an industrial athmospheric distillation column at Shiraz refinery. The control performance of the industrial column using relative gain array (RGA) ...
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The paper presents the computer simulation of a multivariate control algorithm. Industrial relevance is given as the problem is derived from a real plant, an industrial athmospheric distillation column at Shiraz refinery. The control performance of the industrial column using relative gain array (RGA) and relative normalized gain array (RNGA) configurations has been examined for nominal operating capacity and 10% increase in capacity. The results show that RNGA structure remains stable and has an acceptable control performance for both nominal and increased capacity. RGA structure unlike RNGA changes at the increased capacity and has some difficulties in crude oil switch scenario. It has also been shown that the furnace duty will increase considerably in the case of using RGA for operating at increased capacity. The results indicate that RNGA represents better decision for loop pairing and control structure selection and can solve control issues of industrial distillation column specifically for uncertain feed condition.
Research Articles
Industrial Electronics
Mahdi Heidari
Abstract
The power generation from wind turbine are variable because of dependence on environmental conditions and it is important to extract maximum energy from wind. This paper proposes a new method to extract maximum energy from wind turbine systems. The artificial neural network (ANN) is used to estimate ...
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The power generation from wind turbine are variable because of dependence on environmental conditions and it is important to extract maximum energy from wind. This paper proposes a new method to extract maximum energy from wind turbine systems. The artificial neural network (ANN) is used to estimate the wind speed based on the rotor speed and the output power. In addition to ANN, a predictive controller is used to maximize the efficiency of the boost converter. In predictive controller, duty cycle of boost converter is controlled to obtain the maximum power point based on the slope method. One of the most interesting advantages of this controller is simplicity of control and implementation that is leads to fast response and exact tracking. The method has been developed and analyzed by utilizing a turbine directly driven permanent-magnet synchronous generator (PMSG). The simulation results verify the performance of the proposed method. Results show that this method maximizes wind energy extraction with more accuracy and fastness.
Research Articles
Power systems
Zahra Nasiri-Gheidari; Mehrage Ghods; Hashem Oraee
Abstract
In this paper no-load and full-load performance of Permanent Magnet Vernier Generators (PMVGs) is investigated in fully-aligned condition and under different types of mechanical faults. The studied mechanical faults are Static Eccentricity (SE), Dynamic Eccentricity (DE), Inclined Rotor (IR), and Run-out ...
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In this paper no-load and full-load performance of Permanent Magnet Vernier Generators (PMVGs) is investigated in fully-aligned condition and under different types of mechanical faults. The studied mechanical faults are Static Eccentricity (SE), Dynamic Eccentricity (DE), Inclined Rotor (IR), and Run-out (RO). Furthermore, an analytical model is developed to calculate the permeance of the air-gap and the induced voltages in the health machine and under studied mechanical faults. Then, 2-D and 3-D time stepping finite element method is utilized for performance evaluation of the generator. Some discussions are made on the quality of induced voltages, torque ripples, variations of axial and radial forces and the output power of the generator under the mechanical faults considering resistive, inductive and capacitive loads connected to the terminals of the generator. Finally, the performance of an outer rotor conventional permanent magnet generator (CPMG), considering constant dimensions, constant PM, copper and iron usage is compared with the studied PMVG. The performance of two generators is studied in fully-aligned condition as well as under SE and DE.
Research Articles
Power systems
Javid Khorasani; Ehsan Monabbati; Habib Rajabi Mashhadi
Abstract
In this paper, the bidding problem in electricity markets is formulated from the viewpoint of a generation company. With focus on Iran's electricity market structure, the objective is to design an optimal linear bid function considering pay-as-bid pricing mechanism. The market clearing price is considered ...
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In this paper, the bidding problem in electricity markets is formulated from the viewpoint of a generation company. With focus on Iran's electricity market structure, the objective is to design an optimal linear bid function considering pay-as-bid pricing mechanism. The market clearing price is considered as a stochastic variable. The bidding problem is formulated as a nonlinear optimization problem from the viewpoint of a price-taker generation company. Then a numerical study is performed to show the effect of stochastic characteristics of market price on the optimal values of bidding parameters. In order to have more expected profit, a mathematical problem is designed and solved to partition the generation capacity. The main aim of this paper is presentation of a classic method to find the optimal bid function while from the viewpoint of a price-taker generation company in a pay-as-bid electricity market. An example is designed to calculate a linear bid function using the proposed technique. Also a comparison between step-wise and linear bidding is presented.
Research Articles
Power systems
Mohammad Ghiasi
Abstract
Load flow (LF) is one of the most important parts to study and analyze power system operation. In this research paper, a detailed study for load flow analysis in distributed power system (DPS) is presented. A case study of modeling and simulation of the actual power distribution network is implemented ...
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Load flow (LF) is one of the most important parts to study and analyze power system operation. In this research paper, a detailed study for load flow analysis in distributed power system (DPS) is presented. A case study of modeling and simulation of the actual power distribution network is implemented with the electrical transient analyzer program (ETAP) software (version: 12.6). Furthermore, a comparison of common load flow techniques of power distribution is presented. In this assessment, numerical and practical methods including Newton-Raphson (NR), Fast Decoupled (FD), and Accelerated Gauss-Seidel (AGS) are provided and compared. The results (total generation, loading, demand, system losses, and critical report of load flow) are obtained and analyzed. This paper focuses on the detailed assessment and monitoring by using the most modern ETAP software, from high voltage substation (HVS) to the loads. The capability and effectiveness of load flow assessment are demonstrated according to the simulation results obtained with ETAP by applying it to the actual distributed power system of Tehran metro (subway). Once the modeling is performed in ETAP for complete power system, it might be highly beneficial for converting conventional grid into smart grid.
Research Articles
Industrial Electronics
Hossein Shojaeian; Saeed Hasanzadeh; Mojtaba Heydari
Abstract
AbstractThis paper proposes a novel high step-up converter suitable for distributed generation using renewable power sources. The proposed converter includes a dual switches structure, two voltage multiplier cells and a three-windings coupled inductor for achieving high voltage gain. The configuration ...
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AbstractThis paper proposes a novel high step-up converter suitable for distributed generation using renewable power sources. The proposed converter includes a dual switches structure, two voltage multiplier cells and a three-windings coupled inductor for achieving high voltage gain. The configuration of the proposed converter not only reduces the voltage and current stresses of the switches, but also restricts the input source current, which reduces transmission losses and increases the lifetime of the input source. In the proposed converter, the multiplier cells are charged during the switch-on and switch-off periods, which cause to enhance the voltage gain of the converter and improve its productivity. Another feature of the proposed converter is that the inductive leakage energy of the coupled inductor is recycled through a passive clamping circuit which, in turn, has a considerable impact on system efficiency. A comparison is conducted between the performance of the proposed converter and the counterpart converters to demonstrate the proposed converter’s superiority in terms of voltage gain, voltage stress across the switches and diodes and number of components. Theoretical analysis and simulation results are provided to demonstrate the authenticity of the proposed converter.
