Application of the cascaded multilevel inverter as a shunt active power filter

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DSOGI-PLL based power control method to mitigate control errors under disturbances of grid connected hybrid renewable power systems

The control of power converter devices is one of the main research lines in interfaced renewable energy sources, such as solar cells and wind turbines. Therefore, suitable control algorithms should be designed in order to regulate power or current properly and attain a good power quality for some disturbances, such as voltage sag/swell, voltage unbalances and fluctuations, long interruptions, and harmonics. Various synchronisation techniques based control strategies are implemented for the hybrid power system applications under unbalanced conditions in literature studies. In this paper, synchronisation algorithms based Proportional-Resonant (PR) power/current controller is applied to the hybrid power system (solar cell + wind turbine + grid), and Dual Second Order Generalized Integrator-Phase Locked Loop (DSOGI-PLL) based PR controller in stationary reference frame provides a solution to overcome these problems. The influence of various cases, such as unbalance, and harmonic conditions, is examined, analysed and compared to the PR controllers based on DSOGI-PLL and SRF-PLL. The results verify the effectiveness and correctness of the proposed DSOGI-PLL based power control method

Performance Enhancement in Active Power Filter (APF) by FPGA Implementation

The generated electrical power in present days is not able to meet its end-user requirement as power demand is gradually increasing and expected to be increasing more in future days. In the power quality management, the parameters/factors like harmonic currents (HC) and reactive power (RP) yields the major issues in the power distribution units causing transformer heating, line losses, and machine vibration. To overcome these issues, several control mechanisms have been presented and implemented in recent past. The control algorithm based on synchronous reference frame (SRF) offers a better response by dividing the HC and RP. But the SRF based control algorithm requires better synchronization among the utility voltage and input current. To achieve this, the existing researches have used digital signal processing (DSP) and microcontroller, but these systems fail to provide better performance as they face issues like limited sampling time, less accuracy, and high computational complexity. Thus, to enhance the performance of active power filter (APF), we present an FPGA based approach. Also, to validate the performance of the proposed approach, we have used Xilinx 14.7 and Modelsim (6.3f) simulator and compared with other previous work. From the results analysis, it is found that the approach has good performance

Design and implementation of a modified fourier analysis harmonic current computation technique for power active filters using DSPs

The design and implementation of a harmonic current computation technique based on a modified Fourier analysis, suitable for active power filters incorporating DSPs is presented. The proposed technique is suitable for the monitoring and control of load current harmonics for real-time applications. The derivation of the basic equations based on the proposed technique and the system implementation using the Analogue Devices SHARC processor are presented. The steady state and dynamic performance of the system are evaluated for a range of loading conditions

Design and implementation of a single phase active power filter

Various active filter solutions have been proposed in recent years {I], {2], and are still being widely investigated today. This thesis discusses the design and implementation of the shunt AP F topology

Unified Power Quality Conditioner: protection and performance enhancement

The proliferation of power electronics-based equipment has produced a significant impact on the quality of electric power supply. Nowadays, much of the equipment is based on power electronic devices, often leading to problems of power quality. At the same time this equipment is typically equipped with microprocessor-based controllers which are quite sensitive to deviations from the ideal sinusoidal line voltage. Conventional power quality mitigation equipment is proving to be inadequate for an increasing number of applications, and this fact has attracted the attention of power engineers to develop dynamic and adjustable solutions to power quality problems. One modern and very promising solution that deals with both load current and supply voltage imperfections is the Unified Power Quality Conditioner (UPQC). This thesis investigates the development of UPQC protection scheme and control algorithms for enhanced performance. This work is carried out on a 12 kVA prototype UPQC. In order to protect the series inverter of the UPQC from overvoltage and overcurrent during short circuits on the load side of the UPQC, the secondary of the series transformer has to be short-circuited in a reasonably short time (microseconds). A hardware-based UPQC protection scheme against the load side short circuits is derived and its implementation and effectiveness is investigated. The main protection element is a crowbar connected across the secondary of the series transformer and consisting of a pair of antiparallel connected thyristors, which is governed by a very simple Zener diode based control circuit. Also, the software-based UPQC protection approach is investigated, the implementation of which does not require additional hardware

Regulatori struje aktivnih filtara snage za poboljšanje kvalitete snage: Tehnička analiza

Non-linear load deteriorates the quality of current waveforms at the point of common coupling of various consumers. Active power filter (APFs) is used to mitigate the most concern harmonic pollution in an electrical network. The controller part is the nucleus of an active power filter configuration. Active power filter performance is affected significantly by the selection of current control techniques. The active filter and its current control must have the capability to track sudden slope variations in the current reference to compensate the distorted current drawn by the voltage source inverter. Therefore, the choice and implementation of the current regulator is more important for the achievement of a satisfactory performance level. In this survey, technical reviews of various types of controllers covering a wide range have been presented. This work also reveals the advantages and disadvantages of the practiced control strategies. The effectiveness of the study will help the researchers to choose the proper control methods for various applicationsof active power filter.Nelinearni tereti pogoršavaju kvalitetu strujnih valova u točki u kojoj se spaja više potrošača. Aktivni filtar snage se koristi za ublažavanje najvažnijeg harmoničkog onečišćenja strujne mreže. Jezgra aktivnog filtra snage je regulator. Na performanse aktivnog filtra snage značajno utječe odabir upravljačke tehnike. Aktivni filtar i njegova tehnika upravljanja strujom moraju imati mogućnost pratiti nagle skokove u referentnoj vrijednosti struje kako bi mogli kompenzirati izobličenja struje koju vuče inverter naponskog izvora. Zato su izbor i implementacija regulatora struje iznimno važni za postizanje zadovoljavajuće razine performansi. U ovom pregledu su predstavljene tehničke recenzije koje pokrivaju širok raspon regulatora. Ovaj rad također otkriva prednosti i mane korištenih strategija upravljanja. Efektivnost ovog pregleda pomoći će istraživačima da izaberu ispravnu metodu upravljanja za različite aplikacije aktivnog filtra snage

Development of an algorithm for switching compensator control based on the Currents\u27 Physical Components theory

Development of a three-phase switching compensator algorithm, based on the Currents’ Physical Components (CPC) power theory and capable of performing in real time, is the subject of this thesis. The compensator algorithm could be implemented to control a PWM Inverter, which would perform as a shunt switching compensator of harmonic, reactive and unbalanced currents or a customizable combination of the three. The hardware used to demonstrate the ability of the algorithm to perform within the restraints or real time operation is a Motorola DSP56F807 evaluation mode DSP board and a set of voltage and current sensors. The Evaluation Board was programmed, using Metrowerks Code Warrior 7.0©, to provide the compensator control algorithm according to the CPC power theory. The software written to control the compensator is primarily C based, but includes Java beans to control specific setting on the DSP board. After data acquisition and digital signal processing, a CPC based algorithm, developed within this thesis, is the tool used to generate the reference signal. Once the reference signal is attained, the space vector PWM technique is applied to generate PWM outputs, which could be used to control an inverter. The inverter could then inject current into the power system such that the supply current is symmetrical, sinusoidal and in phase with the supply voltage