PWM effect on MPPT for hybrid PV solar and wind turbine generating systems at various loading conditions

Hybrid systems employing different kinds of renewable energy sources, like wind and solar energy conversion systems, are used to reduce generation costs and the pollution of traditional fossil fuel-based electrical generation methods. The current paper presents the design of an off-grid hybrid connection of an 852 W photovoltaic (PV) panel with a 1 kW small-scale wind turbine. This work is based on a study of the effect of the changes in the pulse width modulation (PWM) of a DC/DC converter that was connected to each renewable energy source at various loads. The pulse width can be varied by changing its duty cycle value (D). In this paper, the D value is changed manually for each renewable energy source and automatically using an incremental conductance (IC) and Perturb and Observe (P&O) maximum power point tracking (MPPT) algorithms. The IC algorithm is used for the PV system whereas the P&O algorithm with a smaller step size is used for the PMSG wind turbine. The hybrid system is exposed to different environmental conditions to test the validity of the MPPT algorithm for both renewable energy sources. The results of manual and automatic changes of D values are compared for different loads. The AC output voltage is regulated to obtain a constant RMS voltage at different loads. The hybrid system is tested and simulated using MATLAB SIMULINK R2017a software

Experimental study in reduction of two phase flow induced vibration

Vibration in mechanical devices is one of the major problems in engineering field including power generated industry. In this study we focused on the method and possible equipment design availability in reduction of vibration level. A brief overview of the outcomings of pipeline vibrations is presented, the sources of vibrations are listed and possible solutions for eliminating vibrations are described. Devices for passive quenching of pressure pulsations in pipelines with a two-phase flow are considered. We presented the description of the experimental stand on the investigation of the influence of a two-phase flow on the vibration of sections of a pipeline under different flow patterns of a coolant, as well as the procedure for conducting an experiment to study the properties of developed and manufactured swirl models. An animated model was developed that reflects the relationship of swirl geometry with the reduction of the vibro-displacement of the pipeline as a result of passive action on a two-phase flow

Investigation of the effect of passive vortex inserts of different geometrical shapes on the vibrations reduction efficiency in pipelines with two-phase flow

This paper describes the experimental test bench used in coolant flow research with application of adjusted optical laser system. It is based on the technology of pulsed particle visualization of micro tracers, i.e. Particle Image Velocimetry (PIV system) that allows for the analysis of the microstructure of the hydrodynamic liquid flow passed through the vortex inserts. Optical measurement (PIV-method) of hydro- and aerodynamic characteristics of the coolant flow allowed obtaining the velocity distribution in straight and various curved sections of the pipeline in order to reliably define the vortex formation condition and the occurrence of the pressure gradient on the outer and inner walls of the curved sections. This gives us the opportunity to verify the calculation models describing the problem of passive control (decrease) of the displacement of pipelines of power equipment, and thus to improve the reliability and safe operation of the system in general

A Numerical Analysis of Fluid Flow and Torque for Hydropower Pelton Turbine Performance Using Computational Fluid Dynamics

The difficulty of delivering electrical power to rural areas motivated the researchers to explore more accessible power sources. Hydropower is considered a desirable option due to its sustainability and lower costs. Pelton turbines have been widely used in hydropower plants because of their low installation and maintenance costs. This study provides a computational fluid dynamics (CFD) model for Pelton turbine performance under various flow conditions. The model is based on the conservation of mass principle, Newton’s second law, and the first law of thermodynamics. It is used to predict the torque produced by a turbine at different rotational speeds. Previously published experimental results for the same turbine geometry and flow parameters were used to validate the model’s predictions. Validation revealed that the model can reproduce the experimental results. This provides the required robustness for its use as a tool for turbine design and modification