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This study presents a new H-bridge DC-DC converter-based transformerless dynamic voltage restorer topology (DVR). The proposed system can compensate balanced and unbalanced voltage sag/swell that are the most common electrical power quality problems and offers advantages over conventional DVR topologies by providing the isolation with high-frequency transformer (HFT) rather than bulky injection transformers and by employing shunt converter to eliminate the requirement of an energy storage unit. The system is composed of H-bridge DC–DC converter equipped with a HFT with one primary and three secondary windings and transformerless DVR. The single-phase shift modulation method is used for each series converter independently to provide the bidirectional power flow control of DC–DC converter, whereas in-phase compensation method with a hybrid detection algorithm is used to mitigate voltage sag/swell. An LC filter is employed to attenuate the switching ripple harmonics on the output of the DVR. The performance of the proposed system is verified experimentally on a three-phase, three-wire, 380 V, 10 kVA prototype. [ABSTRACT FROM AUTHOR]

This study presents a multiple harmonic elimination-based feedback controller for shunt hybrid active power filter (SHAPF) to perform an effective harmonic compensation performance in a wide harmonic frequency band. The conventional control methods presented for SHAPF cannot perform an adequate performance, because of the disturbances such as phase delays caused by controller methods and measurement circuitries, tolerances of passive filter components and supply voltage harmonics. In the proposed controller, the conventional feedback controller is improved by using supply side individual current harmonics which are extracted by the synchronous reference frame method. To prevent the performance degradation effects of disturbances, proportional-integral controllers are applied to each d and q components of individual current harmonics. The compensation performance of the proposed method is compared with conventional methods both theoretically and experimentally. The experimental results verify the advanced harmonic compensation performance of the proposed control method. [ABSTRACT FROM AUTHOR]

Artificial neural network (ANN) is a computational algorithm based on the structure and functions of biological neural networks. It is used for modelling of the non-linear systems that cannot be mathematically expressed by the formula and extraction of the system dynamics, expressed by using the complex mathematical equations, such as harmonics. To show the effective usage of ANNs in the power system, the fundamental harmonic of a load with six-pulse thyristor controlled rectifier is extracted with ANN by using the system variables that are difficult to express with each other. Then, a new approach is proposed to generate the reference signal for compensating the harmonics of the current by using discrete fuzzy logic in this study. In addition, a simple and useful method to determine the circuit parameters of the active power filter (APF) is proposed to reduce the rating of the required filter and the capacitor values without affecting its efficiency. Case studies are performed to test the performance of the proposed control algorithm for APF. [ABSTRACT FROM AUTHOR]

Artificial neural network (ANN) is a computational algorithm based on the structure and functions of biological neural networks. It is used for modelling of the non-linear systems that cannot be mathematically expressed by the formula and extraction of the system dynamics, expressed by using the complex mathematical equations, such as harmonics. To show the effective usage of ANNs in the power system, the fundamental harmonic of a load with six-pulse thyristor controlled rectifier is extracted with ANN by using the system variables that are difficult to express with each other. Then, a new approach is proposed to generate the reference signal for compensating the harmonics of the current by using discrete fuzzy logic in this study. In addition, a simple and useful method to determine the circuit parameters of the active power filter (APF) is proposed to reduce the rating of the required filter and the capacitor values without affecting its efficiency. Case studies are performed to test the performance of the proposed control algorithm for APF. [ABSTRACT FROM AUTHOR]