Search

This paper suggests a maiden topology of step-up dc/dc transformer-less converter on basis of the partial power processing concept which has been integrated with the classic boost converter structure. This converter has a high gain as compared to the conventional boost converter. The input dc power is directly connected to the output capacitors and load without being processed by the converter. Where-through, the voltage stress of semiconductors comes to be lower than output voltage. To verify and clarify the suggested converter, the simulation has been presented along with relevant mathematical principles. In this paper, the basic operating principles of the proposed converter are presented along with some experimental results in prototype lab to demonstrate the effectiveness of this converter. [ABSTRACT FROM AUTHOR]

This study is devoted to study and propose a single-phase trans-Z-source-based AC-AC converter with unique features of traditional trans-Z-source converter such as inverted and non-inverted boost and inverted buck output voltage. Output and input operate with same-shared ground, which is very useful in protection. Every aspect of proposed converter is analysed and studied. To prevent current and voltage spikes that are some of the main problems of AC-AC converters, safe commutation is employed. To evaluate the performance of the converter, MATLAB/SIMULINK software is utilised. Moreover, a laboratory prototype of proposed converter is implemented to verify the converter analysis and simulation results. [ABSTRACT FROM AUTHOR]

In this study alinearized Heffron-Phillipsmodel of a single machine power system installed with a unified power flow controller (UPFC) has been presented. The selection of the output feedback parameters for the UPFC controllers is converted to an optimization problem which is solved by cuckoo optimization algorithm (COA). COA, as a new evolutionary optimization algorithm, is used in multiple applications. This optimization algorithm has a strong ability to find the most optimistic results for dynamic stability improvement. The effectiveness of the proposed controller for damping low frequency oscillations is tested and results compared with imperialist competitive algorithm (ICA). The controllers are tested to variations in system loading. There sulks analysis reveals that COA minimized cost function and improved dynamic stability, better than ICA. In addition, the potential and superiority of the proposed method over the ICA is demonstrated. The simulation results analysis shows that the designed COA based output feedback UPFC damping controller has an excellent capability in damping low frequency oscillations and enhance rapidly and greatly the dynamic stability of the power systems. [ABSTRACT FROM AUTHOR]

In this study, a three-phase to three-phase matrix converter with eight switches in each phase is presented. In addition, a simple switching strategy is used to control switches based on the comparison of a reference output voltage value with 12 voltage values obtained from input voltage. One advantage of the simple switching approach is that it is suitable to step down input voltage frequency. So, it is applicable to interface microturbine generation and load. This converter can boost input voltage amplitude with variable reduced frequency with respect to conventional matrix converter using a simple switching technique. Other advantages of the suggested converter is that it is possible to obtain a voltage with low total harmonic distortion by applying the stated switching method as compared to conventional matrix converter. Simulation and experimental results are shown to validate the capability of the suggested converter in the boosting of input voltage at a variable frequency. [ABSTRACT FROM AUTHOR]

Unified Power Flow Controller (UPFC) is one of the most comprehensive FACTS devices which can controls three system parameters independently. In this paper a novel configuration of UPFC which consists of a nineswitch ac/ac converter parallel with a series capacitor has been proposed to inject desired series voltage. It means that operation of nine-switch ac/ac converter in this configuration is the same as combination of two dc/ac converter in conventional UPFC. However, proposed configuration needs fewer power electronics switches and gate drive circuits and control scheme becomes simpler than conventional UPFC configuration. using series capacitor parallel with nine--switch ac/ac converter reduce the injection voltage's THD, eliminate output filter, and reduce the converters power rating in comparison with conventional UPFC composed of series and shunt converters. The proposed UPFC is modelled using MATLAB/SIMULINK software and simulation results are presented to indicate good operation of the novel UPFC. [ABSTRACT FROM AUTHOR]

Forced commutated cycloconverters (FCCs) are very popular topics today which can generate variable frequency and variable voltage in output. These converters include six switches in each phase where operation of these converters depends on switching strategy. This study describes a novel switching strategy for six switches FCC where this strategy transfers seven input voltages to FCC output. In each switching period, among seven input voltages, there are only two input voltages which surround reference output voltage. Hence, the proposed strategy makes these two input voltages around reference voltage transfer to FCC output in each switching period. As a result, average value of FCC output voltage is the same as reference voltage. Main benefits of this switching strategy are minimisation of total harmonic distortion, reduction of dv/dt stresses on the load, lower harmonic components, high-voltage modulation index and performance in unbalance or non-sinusoidal input voltage condition. The operation and performance of the proposed switching strategy has been verified by the simulation and measurement results which were carried out for three-phase to single-phase converter. The proposed switching strategy serves as the conceptual platform for extending the principles to other FCC topologies. [ABSTRACT FROM AUTHOR]

This paper proposes a new topology of DC-DC converters with high gain of boost. The suggested circuit consists of Z-source inverter, high frequency transformer and diode rectifier. In this topology the output voltage amplitude is not limited to DC voltage source and transformer turn ratio similar to traditional high frequency DC-DC converters and can be regulated with Z network shoot-through state control. Besides, it is more reliable against short circuit. By using high frequency modulation, the size of transformer is reduced and it is proper in isolation between high voltage and low voltage circuits. The performance of suggested inverter and switching algorithm are validated with simulation results using MATLAB/SIMULINK software. [ABSTRACT FROM AUTHOR]

In this paper, a STATCOM is used to damp the subsynchronous oscillation in power systems with long transmission lines compensated by series capacitors. By using a new auxiliary subsynchronous damping controller (SSDC), the STATCOM connected at the transmission line is able to damp the subsynchronous resonance (SSR) caused by disturbances. The torsional modes characteristics of the system are investigated in this paper and a new design method is proposed for the SSDC based on a nonlinear optimization to suppress the torsional modes in a wide range of operating conditions. A proper stabilizing signal is chosen for the SSDC input in order to modulate the reactive current reference of STATCOM in the torsional modes. The IEEE second benchmark is used to study the SSR. The eigenvalue and FFT analysis as well as the transient simulation are used to demonstrate the ability of STATCOM with the proposed SSDC in damping the SSR. [ABSTRACT FROM AUTHOR]

This paper presents a novel topology for cascaded multilevel inverters that only two flying capacitors apply single DC source voltage to all sub-multilevel inverters. The output voltages of each sub-multilevel inverters unit, which each unit can produce five voltage levels, are cascaded using low frequency transformers. Suggested topology have advantages of both original flying capacitor and cascaded H-bridge and in the same time reduces the amount of switching devices. DC sources, capacitors and natural self-balancing of the flying capacitors. Besides, it can operates in symmetric an asymmetric states and four algorithms for calculating of turn ratio of transformers have been presented. Simulation results of the proposed inverter are presented and carried out by MATLAB/SIMULINK to verify its voltage generating ability. [ABSTRACT FROM AUTHOR]

This paper proposes the use of a novel Nine-Switch AC/AC Converter topology for doubly fed induction generator (DFIG) applications. DFIG wind turbines use wound rotor induction generators, where the rotor winding is fed through a Nine-Switch AC/AC Converter variable frequency and amplitude PWM converter and regulates to zero the reactive power of stator. The proposed converter uses only nine IGBT devices for ac/ac conversion through a dc link. As compare to conventional back-to-back ac/ac converters, the numbers of power semiconductor switches are reduced in the suggested converter. The proposed topology results in reduction of installation area and cost. The operating principle, control strategy and characteristics of DFIG based proposed ac/ac converter is described in this paper. The performance of proposed DFIG is validated with simulation results using MATLAB/SIMULINK software. [ABSTRACT FROM AUTHOR]

This paper proposes a new switching algorithm for topology of Z-source based cascaded multilevel inverter. In this topology the output voltage is not limited to DC voltage source similar to traditional cascaded multilevel inverter and can be increased with Z network shoot-through states control due to in switching algorithm the traditional zero states turn in to shoot-through states sometimes. Besides, it is more reliable against short circuit. In the proposed topology, each basic unit consists of one DC voltage source, one Z-source and single H-bridge. In this paper the operating principle, switching algorithm and characteristics of proposed topology are presented and performance of suggested topology in the closed-loop control scheme is described in the Dynamic Voltage Restorer (DVR) structure. The performance of suggested inverter and switching algorithm are validated with simulation results using MATLAB/SIMULINK software. [ABSTRACT FROM AUTHOR]