Search results for "Control theory"
showing 10 items of 1333 documents
PVDF based vibration measurements and their correlation with torque estimation in a FOC induction motor drive
2008
This paper presents a study concerning the vibrations generated by an induction motor drive controlled by field oriented control algorithm (FOC). The aim of the study is to identify suitable measurement points and analysis techniques in order to achieve information about vibration generated by an electric drive. Vibrations take origin both by the torque generated by the motor and the motor supply through an inverter, then they are transmitted to neighbouring structures. Torque is estimated on the basis of the estimated flux linkage; vibrations have been both measured and analysed numerically by FEM at two points of the cradle. The numerical and experimental analysis have been carried out fo…
Active load sharing technique for on-line efficiency optimization in DC microgrids
2017
Recently, DC power distribution is gaining more and more importance over its AC counterpart achieving increased efficiency, greater flexibility, reduced volumes and capital cost. In this paper, a 24-120-325V two-level DC distribution system for home appliances, each including three parallel DC-DC converters, is modeled. An active load sharing technique is proposed for the on-line optimization of the global efficiency of the DC distribution network. The algorithm aims at the instantaneous efficiency optimization of the whole DC network, based on the on-line load current sampling. A Look Up Table, is created to store the real efficiencies of the converters taking into account components toler…
Optimizing droop coefficients for minimum cost operation of islanded micro-grids
2017
This paper shows how minimum cost energy management can be carried out for islanded micro-grids considering an expanded state that also includes the system's frequency. Each of the configurations outputted by the energy management system at each hour are indeed technically sound and coherent from the point of view of generation-consumption balancing by exploiting a frequency dependent load flow algorithm. A Glow-worm Swarm Optimization (GSO) algorithm carried out in a 24 hour time frame provides optimized results. A test has been carried out for a residential PV-Storage-Microturbine islanded micro-grid to show the feasibility as well as the efficiency of the proposed approach and results ar…
Energy saving in the aeration process by fuzzy logic control
1998
An aeration fuzzy logic based control system has been developed and tested in the main aerobic reactor of a BARDENPHO process pilot plant. This system has been compared with two ordinary aeration process controllers: one- and two-aeration-level on/off controllers. Energy savings of about 40% over the one-level on/off controller and a more stable closed-loop response have been obtained. Thus, an improvement of about 60% in average deviation can be accomplished by the use of an AFLBC.
Parameter identification of induction motor model using genetic algorithms
1998
The paper deals with methods of identification of the parameters of an induction motor model using genetic algorithms. It is supposed that the inverter supplying the motor is directly accessible for control of the conduction sequences of its power switches. This makes it possible to carry out a test consisting of a transient from standstill to steady-state operation at a given frequency and successive free motion to standstill. During this test, data are acquired referring to stator voltages, and currents and speed. Then, a genetic algorithm is employed with the aim of determining the mechanical and electrical parameters of the model, so as to reproduce the input-output behaviour of a real …
Experimental validation of a direct pre-design formula for TLCD
2014
The passive control of vibrations has received in recent years a great deal of attention from researchers. Several types of devices have been proposed in order to reduce the dynamic responses of different kinds of structural systems. Among them, the Tuned Liquid Column Damper (TLCD) has proved to be very effective in reducing vibration of structures. However, since the equations governing the TLCD controlled systems response is nonlinear, the calibration of TLCD parameters is time consuming and not convenient to perform in a pre-design phase. In this context, it has recently been introduced by the authors a formula that allows to choose the optimal parameters of TLCD in a direct and fast wa…
Finite difference thermal model of a latent heat storage system coupled with a photovoltaic device: Description and experimental validation
2014
Abstract The use of photovoltaic (PV) systems has been showing a significant growth trend but for a more effective development of this technology it is essential to have higher energy conversion performances. Producers of PV often declare an higher efficiency respect to real conditions and this deviation is mainly due to the difference between nominal and real temperature conditions of the PV. To improve the solar cell energy conversion efficiency many authors have proposed a methodology to keep lower the temperature of a PV system: a modified PV system built with a normal PV panel coupled with a Phase Change Material (PCM) heat storage device. In this paper is described a thermal model ana…
A systematic approach for fine-tuning of fuzzy controllers applied to WWTPs
2010
A systematic approach for fine-tuning fuzzy controllers has been developed and evaluated for an aeration control system implemented in a WWTP. The challenge with the application of fuzzy controllers to WWTPs is simply that they contain many parameters, which need to be adjusted for different WWTP applications. To this end, a methodology based on model simulations is used that employs three statistical methods: (i) Monte-Carlo procedure: to find proper initial conditions, (ii) Identifiability analysis: to find an identifiable parameter subset of the fuzzy controller and (iii) minimization algorithm: to fine-tune the identifiable parameter subset of the controller. Indeed, the initial locatio…
Vibration signature analysis for monitoring rotor broken bar in double squirrel cage induction motors based on wavelet analysis
2014
Purpose – The purpose of this paper is to present a diagnosis technique, for rotor broken bar in double cage induction motor, based on advanced use of wavelet transform analysis. The proposed technique is experimentally validated. Design/methodology/approach – The proposed approach is based on a combined use of frequency sliding and wavelet transform analysis, to isolate the contribution of the rotor fault components issued from vibration signals in a single frequency band. Findings – The proposed technique is reliable for tracking the rotor fault components over time-frequency domain. The quantitative analysis results based on this technique are the proof of its robustness. Research limit…
Gain Scheduling H 2 / H ∞ Structural Control of a Floating Wind Turbine
2014
Abstract For wind turbine load mitigation, this paper proposes an active structural control deign of a hybrid mass damper installed at the tower top of a spar-type floating wind turbine. System dynamic model is established based on first principles and the polynomial curve fitting approach, while different steady-state points are derived. Then, a gain scheduling H 2 / H ∞ state feedback controller is designed by solving linear matrix inequalities, which aims to reduce the loading. At last, nonlinear simulations are performed under different wind and wave conditions, and the results demonstrate that more load reduction could be achieved at the expense of more energy consumption in mass dampe…