List of Articles
-
Open Access Article
1 - Reactive Power Management in the Presence of Wind Turbine Considering Uncertainty of Load and Generation
E. Moharamy S. EsmaeiliReactive power management is very important in power systems for the secure transmission of active power, especially when a part of system generation is provided by stochastic sources like wind energy. This paper presents a new algorithm for reactive power management in MoreReactive power management is very important in power systems for the secure transmission of active power, especially when a part of system generation is provided by stochastic sources like wind energy. This paper presents a new algorithm for reactive power management in the presence of wind generators and considering the stochastic nature of these sources and load simultaneously .In this regard, the proposed probabilistic algorithm, minimizes the overall cost function of the system considering the cost of each of the reactive power sources including wind generators. Besides economic issues, the voltage stability margin, having sufficient reactive power reserve in each area of voltage control and considering transmission congestion probability as technical aspects of the planning, have been investigated .Another advantage of this method compared to the previous one, is using of doubly-fed induction generator (DFIG) and its capability in providing reactive power considering the constraints of grid side and rotor side converters. The proposed optimization algorithm uses a multi objective function with different weighting coefficients. This algorithm is applied to minimize total reactive power, cost and losses and maximize voltage stability margin and reactive power reserve, simultaneously, meanwhile the probabilistic nature of wind and load forecasting inaccuracy is considered in this algorithm. The proposed method is implemented on the IEEE 30-bus test system and the simulation results demonstrate the effectiveness of proposed algorithm in real conditions for PMSMs against internal faults, especially inter-turn faults. Manuscript profile -
Open Access Article
2 - Modeling and Analysis of Tower Protection Performance in Order to Coordinate with Environmental Conditions Response and Security Constraint Unit Commitment
M. Yahyaabadi A. SadoughiرIn this paper, effective parameters on lightning performance of communication tower are analyzed. The effect of communication tower height, Influence of weather conditions and adjacent structures are investigated. A 3-D numerical analysis model based on charge simulati MoreرIn this paper, effective parameters on lightning performance of communication tower are analyzed. The effect of communication tower height, Influence of weather conditions and adjacent structures are investigated. A 3-D numerical analysis model based on charge simulation method is applied to calculate the probability of shielding failure and to determine the number of direct lightning strokes to antenna. The communication tower, lightning rod, downward descending leader and upward leaders are modeled by different shapes of charges. For each of the numerous points of all the space above the tower and for different values of lightning current, downward lightning leader is considered to be initiated, and it is distributed step by step until final jump. The electric field around the grounded objects is calculated and upward leader inception criterion is checked in each step. If this criterion were approved for a point, an upward leader would be initiated from that point and then the distribution of upward leader would continue. Upward leaders might be initiated from more than one point but only one of them could strike to downward leader. This process will continue for different conditions and in every situation all the results are analyzed and evaluated. Manuscript profile -
Open Access Article
3 - Lateral Stabilization of a Four Wheel Independent Drive Electric Vehicle Using a Three Layer Controller and Sliding Mode Control
H. Alipour M. Sabahi M. B. B. SharifiaIn this paper, a new controller, for lateral stabilization of four wheel independent drive type electric vehicles without mechanical differential, is proposed. The proposed controller has three levels includes high, medium and low control level. Desired vehicle dynamics MoreIn this paper, a new controller, for lateral stabilization of four wheel independent drive type electric vehicles without mechanical differential, is proposed. The proposed controller has three levels includes high, medium and low control level. Desired vehicle dynamics such as reference longitudinal speed and reference yaw rate are determined by higher level of controller. In this paper, a new sliding mode controller is proposed and its stability is proved by Lyapunov stability theorem. This sliding mode control structure is faster, more accurate, more robust, and with smaller chattering than common sliding mode controllers. Based on the proposed sliding mode controller, the medium control level is designed to determine the desired traction force and yaw moment. In the lower level controller, suitable wheel forces and torques are calculated by an optimal cost function minimizing. Finally, the effectiveness of the introduced controller is investigated through conducted simulations Manuscript profile -
Open Access Article
4 - Multi Objective Network Reconfiguration for Distribution System with Micro-Grids Power Exchange using Max-Min Fuzzy Method and Particle Swarm Optimization Algorithm
A. Fattahi Meyabadi H. SohrabianiA group of small generators and energy storages in the low or medium voltage distribution systems beside of consumers emerge to a new power system called micro grid. Micro grids are designed to have secure and economic operation isolated and connected to the network and MoreA group of small generators and energy storages in the low or medium voltage distribution systems beside of consumers emerge to a new power system called micro grid. Micro grids are designed to have secure and economic operation isolated and connected to the network and exchange electrical energy with distribution system. Hence, they may impact on planning and scheduling of distribution systems. In this case, network reconfiguration is a considerable issue after presenting of micro grids to the system. In the previous studies regarding to this issue, micro grid is considered as a distributed generation which should only produce electricity to the network. In this paper, micro grid is modeled as a power exchanger in the distribution network to study the effect of it on the network reconfiguration. For this purpose, reconfiguration is formulated as a multi objective optimization problem using max-min fuzzy method. In this problem, power loss reduction and load balancing among feeders are two independent objectives and voltage profile, lines congestion, radial network structure and load flow are equality and inequality constraints. Particle swarm algorithm is applied to solve the optimization problem and the reconfiguration over two 33 and 70 buses IEEE test network is shown. Results demonstrate that replacing traditional distribution systems by modern active networks and exchanging power with micro grids can lead to increase the reliability of system and more economic operation. Manuscript profile -
Open Access Article
5 - Improving the Performance of Grid-Connected Cascaded H-bridge Photovoltaic Inverters under Asymmetric Insolation Conditions
H. Iman-Eini M. Amini S. FarhangiIn recent years, solar energy has gained a great deal of attention. Hence, the photovoltaic (PV) systems which convert the solar energy into electricity should achieve high efficiency, low manufacturing cost, and high quality of electric power to attract the consumers. MoreIn recent years, solar energy has gained a great deal of attention. Hence, the photovoltaic (PV) systems which convert the solar energy into electricity should achieve high efficiency, low manufacturing cost, and high quality of electric power to attract the consumers. Although Cascaded H-Bride (CHB) inverter is a suitable choice for injection of PV power into grid, its control issues have not been completely solved. One of the main challenges in CHB inverter is low margin of stability when the H-bridge cells are under imbalance operating conditions. In this paper, a new MPPT algorithm is proposed for a CHB photovoltaic inverter. The proposed approach not only tracks the maximum point of distinct PV arrays under symmetric insolation, but also behaves well under asymmetric insolation conditions. The latter is achieved through shifting the operating point of PV arrays and using the modulation index of H-bridge cells as a degree of freedom. The usefulness and validity of new method is confirmed by simulation and experiments on a 7-level CHB photovoltaic inverter. Manuscript profile -
Open Access Article
6 - CMOS Low-Dropout Voltage Regulator with Controlled Pass Transistor
F. Qaraqanabadi A. SaberkariThis paper presents a low quiescent current low-dropout voltage regulator (LDO) with controlled pass transistor which can work either with on-chip or off-chip output capacitor. The pass transistor of the proposed LDO has lower width in low load condition and has higher MoreThis paper presents a low quiescent current low-dropout voltage regulator (LDO) with controlled pass transistor which can work either with on-chip or off-chip output capacitor. The pass transistor of the proposed LDO has lower width in low load condition and has higher width for moderate to heavy load current and the LDO topology transforms between a two-stage structure in low load current and a three-stage one in moderate to high load current. The proposed LDO topology is designed and simulated in HSPICE in a 0.35 µm CMOS process to provide a 2.8 V output voltage for a 3 V input voltage and is capable to deliver a stable output current in the range of 0-100 mA to the load with a 100 pF on-chip output capacitor while its quiescent current is only 7.5 µA. Without using the adaptively-controlled pass transistor, the maximum output variations of the LDO to the 0-100 mA load transient is 540 mV and its settling time is 11 µs, while using this technique decreases the output voltage variations and settling time to 280 mV and 6.5 µs, respectively. Manuscript profile -
Open Access Article
7 - Joint Blind Equalization and Decoding over Frequency Selective Channels in OFDM Systems Using Particle Filtering Joint Blind Equalization and Decoding over Frequency Selective Channels in OFDM Systems Using Particle Filtering
N. Ghasemi M. F. Sabahi A. R. ForouzanIn this paper a sequential algorithm is proposed for joint blind channel equalization and decoding for orthogonal frequency-division multiplexing (OFDM) in frequency selective channels. This algorithm offers a recursive method to sequentially calculate the posterior pro MoreIn this paper a sequential algorithm is proposed for joint blind channel equalization and decoding for orthogonal frequency-division multiplexing (OFDM) in frequency selective channels. This algorithm offers a recursive method to sequentially calculate the posterior probability for maximum a posteriori (MAP) detection. Recursive calculations are done along the indexes in each OFDM symbol using a particle filter. By defining an appropriate importance function, and a proper prior probability distribution function for the channel tap coefficients (and marginalizing it), an efficient method is presented for joint equalization and channel decoding in OFDM based systems. Performance of the proposed detector is evaluated using computer simulations and its bit error rate is compared with the trained turbo equalizer and a conventional particle filter-based method. The results show that the proposed method outperforms the previously presented particle filter-based method without a need for training data. Manuscript profile -
Open Access Article
8 - Performance Improvement of Generalized Spatial Modulation in Multipath Fading Channels
A. Rezvani R. Saadat J. AboueiSpatial Modulation(SM) is a novel method in use of multiple antenna systems. The main idea is based on information block mapping into two carrying units: a transmit symbol unit that is chosen from constellation members and second unit is the number of active antenna tha MoreSpatial Modulation(SM) is a novel method in use of multiple antenna systems. The main idea is based on information block mapping into two carrying units: a transmit symbol unit that is chosen from constellation members and second unit is the number of active antenna that shows the position of transmit antenna. The use of active antenna position as an extra source of transmit data increases the bandwidth efficiency. Also it doesn't have inter-antenna interference (IAI) and inter-channel interference (ICI) and it's caused to decrease the complexity in receiver side. So SM is a competitor in multiple antenna systems like V-BLAST and space-time coding. More recently generalized spatial modulation (GSM) is presented that use some active antennas instead an active antenna. When the symbol is sent from multiple antennas, it'll get a diversity gain. In this paper we show that by using different channel coding in GSM we can improve bit error rate (BER) without decrease in bandwidth efficiency between 15-40 percent. Manuscript profile -
Open Access Article
9 - A New Non-Isolated SEPIC Converter with High Gain and High Efficiency for Photovoltaic Application
M. Mahmoudi B. Mirzaeian Dehkordi M. NiroomandIn this paper, a new non-isolated SEPIC converter for photovoltaic application is introduced and analyzed. Regarding to low output voltage PV panel and high voltage application of PV systems, a high gain converter is designed. This converter has advantages such as high MoreIn this paper, a new non-isolated SEPIC converter for photovoltaic application is introduced and analyzed. Regarding to low output voltage PV panel and high voltage application of PV systems, a high gain converter is designed. This converter has advantages such as high output voltage gain while keeping the switch voltage stress equal to a regular SEPIC converter, improve the turn-on and turn-off transients of the switch and high efficiency. Also, switching losses and EMI noise are reduced by soft switching method. The MOSFET operates at zero-voltage-switching (ZVS) turn-off and near zero-current-switching (ZCS) turn-on. Manuscript profile