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The smart transformer, a solid-state transformer with control and communication functionalities should provide services to the grid. This paper proposes to use a different frequency respect to the fundamental frequency, to provide such services to the distribution grid. The approach has the main benefit to transfer energy from point to point of the grid, exploiting the lower impedance path that multi-frequency...
A drive train system (DTS) powered by an ideal voltage source and driving a permanent magnet synchronous motor (PMSM) is discussed in this paper. A two-level, three-phase conventional inverter with no harmonic filters on both AC and DC sides is used as means of power conditioning. This DTS is modelled as a double oscillator according to a simplified drive train in an electric vehicle. Commonly used...
This paper designs a multifunctional grid-connected inverter (MFGCI) .It can both utilize the energy in green energy resource (GER) and energy storing device (ESD) and alleviate the harmonic pollution caused by propulsion system in ship power grid properly. Simultaneously, the volume of propulsion transformer is expected to be reduced and the PFD will be less-used or even out of work. The result of...
This paper presents the principle and implementation of the wavelet PWM (WPWM) technique based on dyadic-type multi-resolution analyses (MRAs) for single-phase inverters, analyzes and gives the inverter's output features at different parameters based on WPWM technique, which is beneficial to choose suitable parameters. Finally, according to the harmonic eliminating principle, compares WPWM with SPWM...
This The performance analysis of a solar power plant is very important from the point of view of technology and economy. The PV systems incorporate power conditioning units, which are harmonic generating devices. Thus have an influence on the quality of supply, reliable operation of system equipments and life of the system components. The harmonics generated at the output of the solar power plant...
In this paper, models of central-station PV plants, are represented. The detailed and equivalent PV models and area of their applications and limitations for different studies (load flow, short circuit calculation, RMS modeling and harmonic analysis) are proposed. Levels of detailing from one node to in-depth model of PV plant are overviewed.
Many inverters are quoted as having a PF of better than 0.95 when in reality, the true power factor is between 0.5 and 0.75. This paper describes the influence of grid-connected inverters on the distribution grid. The impact of the voltage distortion from the inverter to the distribution grid is relative small without grid impedance. When the grid impedance is involved, the distortion will become...
This paper presents the theoretical analysis of the inherent reason of current harmonic and power oscillation phenomena in case of operating the microgrid inverter under unbalanced grid voltage conditions. In order to flexibly control the current harmonic and power oscillation, a new stationary frame control strategy is proposed. It has a simple control structure due to no need of a phase-locked loop...
Energy and sustainability are now on the top agenda of many governments. Smart grids have become one of the main enablers to address energy and sustainability issues. Many research centres have been set up worldwide to address various aspects of energy and sustainability. Renewable energy, distributed generation, hybrid electrical vehicles, more-electric aircraft, all-electric ships, smart grids etc...
Power electronic converters connected to a dc bus are sources of undesirable harmonics towards the dc side due to an inherent high-frequency switching used for the power processing. Three-phase inverters are widely used in many applications like motor drives and active rectifiers. With a SPWM control the dc bus voltage is not fully utilized, so a zero sequence injection method is commonly used to...
This paper provides a comparison between three different topologies, which can be used in current harmonic mitigation. The considered solutions are as follows: a pure active filter, a hybrid filter composed from a series connection of shunt passive and active filters and a newly proposed hybrid filter topology. In this paper the inverter power rating is seen as the main factor of interest, because...
Due to several reasons current source inverters (CSI) are seldom used compared to the voltage source inverter (VSI) principle. On the one hand they need reverse blocking semiconductors, on the other hand their DC-link element is an inductor. Furthermore the topology is affected by the unavoidable resonant behaviour of its output network because of the necessary output capacitors. Until now all efforts...
The paper presents measurements of waveform distortion from six solar-power installations and three wind-power installations. The main emphasis is on the emission of low-order odd harmonics as a function of active-power production. It is concluded that the emission levels are low, that there is in most cases just a weak correlation with active power production, and that every installation is unique...
The design of optimized modulation schemes at low pulse ratios, e.g. Selective Harmonic Elimination (SHE), has been widely studied. However, most previous work has focused on half-wave symmetry pulse patterns. For variable speed and variable torque applications, non-half-wave symmetry SHE modulators depending on the power factor angle still achieve highly efficient inverters in many power factors...
The paper evolves a new hybrid modulation strategy to incarnate a higher quality sinusoidal output voltage from a modified dual bridge multilevel dc-link inverter (DBMLDCLI) topology. The scheme is developed to minimize the switching loss in power devices. The proposed modulation strategy is derived from the fundamental switching and pulse width modulation (PWM) through modified sinusoidal reference...
Cascaded multilevel inverter is a superior option for static var compensators and active power filters, especially in high voltage and/or high power applications due to its modular structure and distributed voltage stress and switching losses among switching devices. The influence of semiconductor device on-state voltage drops on the harmonic current and reactive power compensation in a cascaded multilevel...
Adjustable speed drive is becoming a significant load component for power distribution. It involves the use of Induction motors comprising of Wound rotor type & squirrel cage. This paper involves analysis, control and modeling of induction motors and also investigates its effects on Total current harmonic distortion on an adjustable speed by the use of PWM generator and Vector control method....
The previous studies have shown the drawbacks of conventional inverters, specially for high power application. From the beginning of 21st century, drastic improvement in the harmonic profile and increased power rating of MLI made them highly popular for high power application. MLI's are widely utilized in industrial field employing motor drives, static VAR compensators and renewable energy systems,...
A novel and simple control technique for reducing current harmonics in a grid connected non linear load using composite observer is discussed in this paper. In this scheme, In-phase and Quadrature components of fundamental as well as harmonics of load current and inverter current are estimated using composite observer. Estimated harmonics from the load current are fed forward to generate the control...
Dual active bridge (DAB) converter is widely used in photovoltaic power system. It usually works as an interface between DC voltage bus and storage units with its main function of balancing the power flow of the entire system through maintaining the bus voltage stable. However, due to the pulsating output power of the inverter, there will be an ac current pulsating at twice the output frequency in...
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