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Harmonic Mitigation in Wind Turbine Energy Conversion Systems

Permanent magnet synchronous generators (PMSG applied to wind energy conversion system (WECS) using variable speed operation is being used more frequently i wind turbine application. Variable speed systems have several advantages over the traditional method of operating win turbines, such as the reduction of mechanical stress and a increase in energy capture. To allow the variable speed operation of the PMSG WECS a conventional three-phase bridge rectifier (BR) with a bulky capacitor associated with voltage source current controlled inverter (VS-CCI) is used This simple scheme introduces a high intensity low frequency current harmonic content into the PMSG and consequently increases the total loses in it. Subsequently, decreases the power capability of the system. This paper presents comparative simulation study between three different approaches applied to harmonic mitigation in PMSG WECS The studied techniques are: a) harmonic trap filters (HTF), b single-switch three-phase boost rectifier (PFC) and c) a three phase boost type PWM rectifier (PWMREC).

The influence of programmed start ballast in T5 fluorescent lamp lifetime

In this paper it is analyzed the influence of programmed start ballast in T5 fluorescent lamp lifetime. Different rapid cycle test are discussed, including the manufactures ones, to verify the behavior T5 fluorescent lamp lifetime under different starting methods. Alternative electronic ballast with programmed rapid-start is proposed for a 28 W/T5 fluorescent lamp using voltage-preheating. The results showed that is possible to increase the T5 fluorescent lamp lifetime using the programmed start ballasts

Determination of EMI emission in power factor preregulators by design

A tool for determination of power factor preregulator (PFP) conducted electromagnetic interference (EMI) emission by design is presented. This method allows the determination of the amplitude of the first harmonic in dBspl mu/V in accordance with the CISPR 16 standard, for the commonly employed PFP power converters. It can therefore can be a useful aid for designers.<<ETX>>

Dynamic modeling of a ZETA converter in DCM applied to low power renewable sources

This paper presents the dynamic modeling of a ZETA converter in discontinuous conduction mode (DCM) applied to low power renewable sources using the generalized switch averaging technique. The whole system consists of a ZETA converter associated with a full bridge inverter operating at low frequency. Thus, the system works as a sinusoidal low power source. The ZETA converter plays the main role in this arrangement, producing a rectified sinusoidal current waveform synchronized with the power grid. Initially it is presented a brief analysis of the system, as well as the characteristics that make possible the dynamic analysis in DCM. The generalized switch averaging technique are discussed, and also the small-signal analysis of the ZETA converter. In order to validate the current study experimental and simulations results are presented.

Dynamic modeling of a sinusoidal inverter based on ZETA converter working in DCM for PV arrays

This paper presents a dynamic modeling study for a ZETA converter working in discontinuous conduction mode (DCM) applied to low power renewable energy sources using the generalized switch averaging technique. The modeling is performed considering only resistive loads. The whole system consists of a ZETA converter, using a sinusoidal pulse width modulation (PWM), associated with a full-bridge (FB) inverter, operating at low frequency, in order to synthesize a sinusoidal waveform at its output. Thus, the system works as a sinusoidal low power source. Initially it is presented a brief analysis of the system, as well as the characteristics that made possible the dynamic analysis in DCM. The generalized switch averaging technique is discussed, and also the small-signal analysis of the ZETA converter. In order to validate the current study experimental and simulation results are presented.

Low power solar system grid-tied with MPPT based on temperature compensation

This paper presents a power converter for grid connection of renewable energy sources, consisting of a ZETA converter associated with a bridge inverter operating at low frequency. The Zeta converter, operating in the discontinuous conduction mode (DCM), produces a rectified sinusoidal current waveform synchronized with the electric grid. The full-bridge inverter, connected to the output of the Zeta converter, is to reverse every 180° the current generated by the Zeta converter. A low cost MPPT based on the linearization of PV panels characteristics and temperature compensation is presented. An analysis of the Zeta converter operating in DCM is presented with converter design considerations, followed by the control strategy and experimental results for a 100 Wp PV system.

Study and Implementation of an Electric Fence Energizer

This paper introduces fundamental concepts of electric fence technology and present a new design procedure for a livestock electric fence energizer circuit and impulse transformer. This work is based on a study developed in a Master Thesis. The available information in this field is practically restricted on industry builders know how and their field experience. In this paper, the Energizer equipment is rounded about many concepts, safety standards and data performance that are discussed. An electric circuit simulation and prototype of Electric Fence Energizer Equipment for livestock use are showed.

A PV module-integrated inverter using a Ćuk converter in DCM with island detection scheme

This paper reports a study on a grid-tied photovoltaic system, using a microinverter based on Ćuk converter working in DCM. Since, when the Ćuk converter is working in DCM, its output voltage presents a linear behavior in relationship to its duty cycle. Therefore, the duty cycle must have a sinusoidal behavior, in absolute value, in order to generate a rectified sine current waveform, at its output. The connection of a full bridge current source inverter in cascade with the Ćuk converter, allows obtaining a sinusoidal current waveform at the microinverter output. One of the most important challenges on microgeneration systems is the island detection. In this sense, if the system is unable to detect the islanding, this may cause power quality degradation, electrical safety threats, especially related to maintenance crews, and damage to third-party devices connected to the same power grid.

Anti-islanding applied on a single-stage microinverter based on zeta converter for distributed microgeneration

The distributed microgeneration was regulated in Brazil in 2012. The connection of microgeneration systems to the utility grid can bring some challenges, like the islanding phenomenon. In this sense, an anti-islanding system must be designed to protect the microgeneration system, users, apparatus and the utility grid. If the islanding is not detected, some problems can occur, such as: degradation of power quality, threatens to safety of maintenance crews, damage to third party equipment connected to the same power grid, and during reclosing, if occurs a phase displacement between the grid voltage and the inverter output voltage some damage to the distributed generation system is expected, in the present scenario, the destruction of the microinverter is probable. In this paper will be presented study and the development of a very simple active islanding detection method dedicated to microinverters, which are used to inject into the mains the power generated from a single PV module. As an example, a microinverter based on Zeta converter working at DCM is discussed.

Improving performance of the P&O MPPT using derivative of photovoltaic panel voltage

This paper proposes a modified maximum power point tracking method (Perturbation and Observation) based on the use of the information from the derivative of power and the derivative of the voltage on the PV panel. The main contribution of this work resides in the employment of the derivative of voltage that is used to determine instantaneously the increment or decrement ratio of the converter duty cycle. The use of this derived signal improves the performance of the proposed MPPT method in comparison to the conventional P&O strategy, considering the dynamic system response, steady state error and robustness (against different irradiation and temperature profiles). In order to validate this MPPT proposal, a prototype of a microinverter based on the flyback converter aiming at connecting PV panels to the power grid was implemented. The microinverter control strategy was held on the Matlab/Simulink© environment together with the dSPACE© platform. This paper presents the simulation and experimental results along with their analysis.