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In this paper, a new control mechanism has been proposed for grid-connected three-phase inverter that provides regenerative energy recuperation in direct current (DC) rail transit. In DC rail transit, line voltage can change dynamically depending on the regenerative energy generated by the trains during braking. In order to respond rapidly to dynamic changes in line voltage, a proportional-integral-derivative (PID) controller designed based on the dominant pole assignment method has been used in the control structure of the inverter. With the proposed control mechanism, the PID controller design has been performed considering the current loop. Thus, the design accuracy has been increased. The derivative effect of the PID provides fast response to these changes in line voltage by increasing the speed of the system response and the slow dynamic response of PI-based control structure has been improved. In addition, a new operating strategy that considers two different voltage values, unlike the systems that operate at constant voltage value in the literature, is proposed. This operating strategy provides more regenerative energy recovery by increasing the inverter operation region and contributes to energy efficiency. Finally, a detailed model of a real system has been developed in Matlab/Simulink environment. The simulation results comparing the performance of the PID-based control structure with the PI-based control has been presented to illustrate the feasibility and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Power quality (PQ) problems have become a serious concern of both power suppliers and end user customers with the deregulation of the electric power market. In the recent years, power electronics based compensation devices with advanced technology has been required due to the inadequate of conventional compensation devices to improve PQ in utility grid. This paper presents a comprehensive review of shunt compensating custom power devices (CPD) connected to distribution system mainly Distribution Synchronous Static Compensator (DSTATCOM) and Active Power Filter (APF). A broad overview on various control methods to compansate different PQ problems used in DSTATCOM and APF's and the main operation principles of these devices are provided. The practical applications and recent research advances on DSTATCOM and APF's are presented by reviewing nearly 120 papers. [ABSTRACT FROM AUTHOR]

In this paper, a novel control technique which is a particular implementation of the quasi square wave method has been proposed for a single-phase inverter drive. With the proposed control technique, 3rd and 3rd order harmonics together with even harmonics of the inverter output voltage waveform are eliminated as in a six-step inverter. An output voltage waveform with less harmonic content for one output period of the inverter operation is produced using the same switching rate as that of quasi square wave method. Output voltage control is performed by using a variable DC link inverter. Matlab/Simulink models of the proposed system, and the inverter system with quasi square wave modulation technique have been obtained. The comparative simulation results for both techniques are given at various output frequencies. Open-loop V/f control has been applied to both inverters feeding an R-L load, V/f controlled inductive and single-phase induction motor loads. Superiority of the proposed technique to the conventional quasi square wave modulation technique has been shown with the output waveforms and their spectra. [ABSTRACT FROM AUTHOR]

Distribution Static Synchronous Compensator (D-STATCOM) is an inverter based custom power devices used to improve power quality problems in distribution systems. In this paper, design of inverter, measurement, protection and dead-time circuits needed to build experimental setup of three-level H-bridge inverter based D-STATCOM is explained in detail. In addition, selection of passive elements which are coupling inductance and dc-link capacitor being important for dynamic response of compensator is given. In experimental study, DS1103 controller card from dSPACE firm is used to transfer data between D-STATCOM and computer. D-STATCOM's ability for reactive power support is tested in experimental setup by changing of iqref as on-line and some results are given. [ABSTRACT FROM AUTHOR]

In this paper, dynamic analysis of permanent magnet synchronous motor (PMSM) fed by sinusoidal PWM (SPWM) controlled voltage source inverter (VSI) was studied. Similar to separately excited DC motor, torque and exciting currents are controlled individually by applying vector control technique to the PMSM. Consequently, improving the motor performance is aimed in this study. Currents and speed are controlled with PI controllers. A digital signal processor card ADMC401 developed by Analog Devices was used for implementing vector control algorithm and producing switching signal for VSI. The PMSM was operated under several speed and load conditions. Test results obtained from experiments are presented and then the dynamics of the drive system are also analyzed. [ABSTRACT FROM AUTHOR]

In this paper, the effect of carrier waveform variations on inverter output voltage in multilevel inverters is examined. For this aim, carrier waveforms with various frequency and amplitude are constructed and compared with the reference sinusoidal signals. The obtained PWM waveforms are then applied to the power switches of the inverter. A five-level inverter prototype implemented and the real-time signals are produced using dSPACE DS1103 controller board and software's. The proposed multilevel sinusoidal PWM (SPWM) strategy is tested experimentally and the results obtained are presented. [ABSTRACT FROM AUTHOR]