International Journal of Smart Electrical Engineering
Year:2015 | Volume:4 | Issue:3|Papers Count:8

Control of three phase inverters has been an important issue in recent years. This paper proposes active disturbance rejection control (ADRC) scheme for controlling three phase inverters. The main advantage of ADRC that motivated us for using this controller for inverter is that it is model independent. This controller is used in a double loop structure including an inner current loop and outer voltage loop. A case study has been simulated in SIMULINK to demonstrate the advantages of ADRC in control of inverters over PI controller. Simulation results demonstrate that load changes have no impact on performance of this control method and it is not sensitive to any uncertainty in parameters of the inverter.

Shaded pole induction motors, despite the simplicity and low cost, are difficult to analyze particularly in the equivalent circuit methods, due to the asymmetric structure, saturation, harmonics, inaccurate estimation of leakage inductances and skew. Hence, 3D numerical methods could be very useful in the design and optimization stage. This paper presents the 3D transient finite element analysis (3DTFEM) of a 1/60HP, 2-pole prototyped, restructured shaded pole induction motor that has been designed and optimized using genetic algorithm technique. Experimental test has been carried out by a hysteresis brake dynamometer to determine the motor performance. Detailed comparisons among 2D, and 3D finite-element analysis, and experimental results are presented, which confirm the potentials of the new restructured shaded pole motor to achieve lower cost and higher efficiency objectives than the previous designs.

In this paper, two new cascaded inverters are proposed, by using the series connection of new Submultilevel inverters. Each of the proposed Submultilevel inverters consists of three batteries and eight power switches. Four algorithms are presented to determine the voltages of these batteries for each of the proposed structures. In this study the comparison between the proposed structures with conventional structures has been done. At first, the proposed algorithms of new structures are compared with each other and after that comparisons between proposed structures based on selected algorithms and the traditional structures are performed. This comparison shows that the proposed inverters can produce high number of output voltage levels due to determined number of power electronic switches. Also blocked voltage of the proposed structures is smaller than other compared structures which leads to reduce size and weight of the proposed inverters. Other advantages of these structures are reduction of voltage sources number, DC sources variety, the conduction losses and the number of power diodes. In order to demonstrate the correct operation of the proposed structures and applied algorithms, simulation results by using PSCAD/EMTDC software are shown.

This paper proposes a novel robust control scheme based on delay-dependentH ∞for unified power quality conditioner (UPQC) in a microgrid under the influence of the delay and parameter uncertainties. A new UPQC model considering the effects of the delay and parameter uncertainties is established. Then, the H ¥ controller is designed based on the cone complementarity linearization (CCL) algorithm. Finally, the effectiveness of the proposed control method is demonstrated by numerical simulations.

This paper proposes an optimal transmission expansion planning (TEP) which is based on determining share of each line in merchandizing surplus (MS) of system, determining by Independent System Operator (ISO). The more share of a line in MS of system denotes the priority of a line for expansion. The procedure of determining MS of each line in a power system is based on determining the MS share of each energy exchange between certain generator and certain demand bus in the power system. By analyzing all energy exchange the optimal planning of transmission line is obtained by ISO. The variable revenue of a Transco is related to performing the optimal planning of transmission lines which is obtained through ISO. The proposed method determines the TEP economical resources and the procedure of receiving these resources (MS of system) from generators and customers. By performing proposed method Transco capacity withholding and misusing is prevented spontaneously caused by relating the revenue of Transco to its optimal performance.

In this paper, photovoltaic (PV) grid-connected inverter which is the core device in PV grid-connected system has been in depth research. An improved predictive current controller has been developed by the Authors for single-phase grid-connected voltage source inverters (VSI). Based on DSP TMS320LF2407A, a 10 kW single-phase grid-connected inverter has been built in this paper. Thus is aimed at use in distributed generation. Because of the powerful real time processing ability of the DSP, the output power factor of the PV inverter connected with grid can be controlled to unity. The composition of main circuit and control loop is described in detail and the operating principle of each functional block is analyzed deeply. The experiment results show that the improved predictive controller has a superior performance. The single-phase grid-connected VSI implemented with the proposed predictive controller has shown very low current THD in laboratory test.

This paper proposes a new method for parameter estimation of distorted single phase signals, through an improved demodulation-based phase tracking incorporated with a frequency adaptation mechanism. The simulation results demonstrate the superiority of the proposed method compared to the conventional SOGI (Second-Order Generalized Integrator) -based approach, in spite of the dc-offset and harmonic distortions.

In recent years, significant research efforts have been devoted to the optimal planning of power systems. Substation Expansion Planning (SEP) as a sub-system of power system planning consists of finding the most economical solution with the optimal location and size of future substations and/or feeders to meet the future demand. The large number of design variables, and combination of discrete and continuous variables makes the substation expansion planning a very challenging problem. So far, various methods have been presented to solve such a complicated problem. Since the Bacterial Foraging Optimization Algorithm (BFOA) has been proper results in studies of power systems, and has not been applied to SEP problem yet, this paper develops a new BFO-based method to solve the SEP problem. The technique discussed in this paper uses BFOA to simultaneously optimize the sizes and locations of both the existing and new installed substation and feeders by considering reliability constraints. To clarify the capabilities of the presented method a typical network is considered and the results of applying GA and BFOA on the network are compared. The simulation results demonstrate that the BFOA has the potential to find more optimal results than the other algorithm under the same conditions. Also, the fast convergence, consideration of real-world networks limitations as problem constraints and simplicity in applying to large scale networks are the main features of the proposed method.