Search results for " speed"
showing 10 items of 641 documents
Experimental Investigation of Stall and Surge in a Multistage Compressor
2016
Flow instability conditions, in particular during surge and stall phenomena, have always influenced the operational reliability of turbo-compressors and have attracted significant interest resulting in extensive literature. Nowadays, this subject is still one of the most investigated because of its high relevance on centrifugal and axial compressor operating flow range, performance and efficiency. Many researchers approach this important issue by developing numerical models, whereas others approach it through experimental studies specifically carried out in order to better comprehend this phenomenon. The aim of this paper is to experimentally analyze the stable and unstable operating condit…
Robust Predictive Control of a variable speed wind turbine using the LMI formalism
2014
This paper proposes a Robust Fuzzy Multivariable Model Predictive Controller (RFMMPC) using Linear Matrix Inequalities (LMIs) formulation. The main idea is to solve at each time instant, an LMI optimization problem that incorporates input, output and Constrained Receding Horizon Predictive Control (CRHPC) constraints, and plant uncertainties, and guarantees certain robustness properties. The RFMMPC is easily designed by solving a convex optimization problem subject to LMI conditions. Then, the derived RFMMPC applied to a variable wind turbine with blade pitch and generator torque as two control inputs. The effectiveness of the proposed design is shown by simulation results.
A Flux and Speed Observer for Sensorless SPIM Applications
2010
It is usual to find single-phase induction motor (SPIM) in several house, office, shopping, farm, and industry appliances, which is become more sophisticated and requires the development of high performance alternatives to drive a SPIM. All proposed strategies to improve the performance SPIM need the evaluation of the rotational speed or position information. Since the use of conventional sensors to measure the rotational speed cannot be justified for SPIM applications, the adoption of a sensorless strategy is a more reasonable option for these cases. This paper presents a flux and speed observer for sensorless applications involving SPIMs. The performance of the proposed observer is verifi…
Linear parameter‐varying modelling and control of an offshore wind turbine with constrained information
2014
This study deals with linear parameter-varying modelling and output-feedback H ∞ control design for an offshore wind turbine. The controller is designed with consideration that not all the information in the feedback loop will be used. This constraint is incorporated into the design procedure. Constrained information means that a special zero-non-zero pattern is forced upon the gain matrix. The constrained controller is obtained based on parameter-dependent Lyapunov functions and formulated in terms of linear-matrix inequalities. Since the functions are dependent on the wind speed and accurate wind speed measurements are rarely available in practice, an extended Kalman filter is used to est…
A discussion on variants of stand-alone electric powerplant equipped with transverse flux generators
2015
The paper discussed several designed variants of TFG with different number of poles, speed and dimensional coefficients starting from two base module variants with a rated power of 8kW and 11 kW respectively. The proposed layout came from reluctance one and it is suitable to equipped stand-alone electric power plant being a proper solution for isolated farms. The influence of large number of poles on torque density values obtained at low rotational speed is discussed in paper.
Monte Carlo simulation for the response analysis of long-span suspended cables under wind loads
2004
This paper presents a time-domain approach for analyzing nonlinear random vibrations of long-span suspended cables under transversal wind. A consistent continuous model of the cable, fully accounting for geometrical nonlinearities inherent in cable behavior, is adopted. The effects of spatial correlation are properly included by modeling wind velocity fluctuation as a random function of time and of a single spatial variable ranging over cable span, namely as a one-variate bi-dimensional (1V-2D) random field. Within the context of a Galerkin`s discretization of the equations governing cable motion, a very efficient Monte Carlo-based technique for second-order analysis of the response is prop…
Impact of wind speed on ventilation performance within a container installed with photovoltaic inverter
2017
Abstract PV inverter needs proper ventilation for reducing the heat dissipation of the electronic components. In this work, a container installed with PV inverter is considered with different configurations of cooling channels within the container for ventilation analysis. Typically, high capacity PV inverters are installed inside the container and therefore inverters, are not experiencing external wind effects and it depends on the configuration of cooling channels. In this work, the main cooling channel is located at the top of the inverter; inlet and outlet ventilation holes are located on the side of cross ventilation. They help in analyzing the cooling design, dependent on site specifi…
Analysis of the maximization of wind turbine energy yield using a continuously variable transmission system
2017
Abstract In this paper, an analytic study of the subject of mechanical power transmission in HAWT wind turbine has been carried out. For the most part, the study analyzes the use of continuously variable transmission (CVT) in order to allow the turbine and the electric generator to couple, allowing in turn, an unremitting transmission ratio adjustment. In low-wind sites, the design criteria suggest an oversizing of the wind turbine in order to generate adequate electrical power even at low wind speed. The proposed solution enhances the space of operating points since it allows the electric generator to release the rotational speed from the turbine one (limited due to structural integrity). …
On the assessment of power consumption and critical impeller speed in vortexing unbaffled stirred tanks
2017
Abstract Unbaffled stirred tanks are increasingly recognized as a viable alternative to common baffled tanks for a number of processes and bio-processes where the presence of baffles is undesirable. Notwithstanding the increasing industrial interest towards unbaffled tanks, available experimental information on their behaviour is still very poor, even for important parameters such as mechanical power drawn and critical impeller speed (Ncr) at which the transition between non-aerated (sub-critical regime) and aerated (super-critical regime) conditions occurs. In this work the influence of Reynolds and Froude numbers on power consumption characteristics of unbaffled stirred tanks is presented…
Interior permanent magnet synchronous motors: Impact of the variability of the parameters on their efficiency
2016
In the scientific literature, various authors presented different control strategies aimed to increase the efficiency of the interior permanent magnet synchronous motors. These strategies, starting from a well-known mathematical model of the dynamic behaviour of the motor, are able to reduce the power losses acting on the magnetizing component of the stator current. However, none of the proposed approaches takes into account that, varying the working conditions of the motor, also the values of the parameters, which have an impact on the power losses, can vary. In this paper, therefore, starting from an accurate measurement of the motor characteristics for various values of speed and load, w…