Search results for "Control theory"
showing 10 items of 1333 documents
Impact of Demand Response Control Logic on Isolated Island's Distribution Networks
2019
The work presents the results of a study regarding the impact of some Demand Response control logics on an isolated distribution network. The proposed control is divided into precise steps in which the coordination between the general aggregator controller and the single local Energy Management Systems is developed and illustrated with details. The control is applied to the flexible loads and to the storage systems of photovoltaic plants installed at the end-users' houses and connected to the network. The study is carried out delivering a suitable network model of the island's system, with the implementation of load profiles for all the loads of the network for a total simulation time of 24…
An advanced control strategy for biological nutrient removal in continuous systems based on pH and ORP sensors
2012
[EN] A fuzzy logic-based control system that uses low-cost sensors for controlling and optimizing the biological nitrogen removal in continuous systems has been developed. The novelty of this control system is the use of several pH, ORP, and dissolved oxygen (DO) sensors instead of on-line nitrogen sensors/analyzers. The nitrogen control system was developed and implemented in a UCT pilot plant fed with wastewater from a full-scale plant. The developed nitrification controller allows the effluent ammonium concentration to be maintained below the effluent criteria discharge with the minimum energy consumption. The denitrification process controller allows the energy consumption derived from …
Update on desiccant wheel model
2004
This short communication presents the update on the desiccant wheel models, developed earlier by the present authors. It is to be mentioned here that the psycrometric model presented earlier (Int. J. Energy Res., 2003; 27:17) is valid only for the desiccant wheel running with identical volume air-flows in supply and regeneration sides. However, when system runs with volume air flow ratio between supply and regeneration side (α), different from 1 (one), the model need further modifications. In the present work, correction factors were developed and incorporated in order to update the earlier model for predicting correctly the temperature and humidity of processed air at the outlet of desicca…
Model-Based Decision Support System for Individual Prescription of the Dialysate Bicarbonate Concentration in Hemodialysis
1992
A decision support system has been developed that determines the optimal dialysate bicarbonate concentration in hemodialysis therapy for each patient individually. The knowledge about the behavior of the acid-base state during treatment has been provided by a mathematical model for the description of dynamic exchange processes during hemodialysis. This model simulates the sodium and water distribution, the acid-base state as well as the ventilation. The decision support system uses the model for the prediction of the end-dialysis acid-base state and calculates by means of linear optimization the dialysate bicarbonate concentration which is necessary to reach a specified end-dialysis state.…
Gaussian and non-Gaussian stochastic sensitivity analysis of discrete structural systems
2000
Abstract The derivatives of the response of a structural system with respect to the system parameters are termed sensitivities. They play an important role in assessing the effect of uncertainties in the mathematical model of the system and in predicting changes of the response due to changes of the design parameters. In this paper, a time domain approach for evaluating the sensitivity of discrete structural systems to deterministic, as well as to Gaussian or non-Gaussian stochastic input is presented. In particular, in the latter case, the stochastic input has been assumed to be a delta-correlated process and, by using Kronecker algebra extensively, cumulant sensitivities of order higher t…
Batch fermentation process: Modelling and direct sensitivity analysis
2009
Based on a nonlinear model, this article realizes an investigation of dynamic behaviour of a batch fermentation process using direct sensitivity analysis (DSA). The used nonlinear mathematical model has a good qualitative and quantitative description of the alcoholic fermentation process. This model has been discussed and validated by authors in other studies. The DSA of dynamic model was used to calculate the matrix of the sensitivity functions in order to determine the influence of the small deviations of initial state, control inputs, and parameters from the ideal nominal values on the state trajectory and system output in time. Process optimization and advanced control strategies can be…
Validation of a New Method for the Diagnosis of Rotor bar Failures via Wavelet Transformation in Industrial Induction Machines
2006
[EN] In this paper, the authors propose a method for the diagnosis of rotor bar failures in induction machines, based on the analysis of the stator current during the startup using the discrete wavelet transform (DWT). Unlike other approaches, the study of the high-order wavelet signals resulting from the decomposition is the core of the proposed method. After an introduction of the physical and mathematical bases of the method, a description of the proposed approach is given; for this purpose, a numerical model of induction machine is used in such a way that the effects of a bar breakage can clearly be shown, avoiding the influence of other phenomena not related with the fault. Afterward, …
The Use of the Wavelet Approximation Signal as a Tool for the Diagnosis of Rotor Bar Failures
2005
[EN] The aim of this paper is to present a new approach for rotor bar failure diagnosis in induction machines. The method focuses on the study of an approximation signal resulting from the wavelet decomposition of the startup stator current. The presence of the left sideband harmonic is used as evidence of the rotor failure in most diagnosis methods based on the analysis of the stator current. Thus, a detailed description of the evolution of the left sideband harmonic during the startup transient is given in this paper; for this purpose, a method for calculating the evolution of the left sideband during the startup is developed, and its results are physically explained. This paper also show…
Robust stabilisation of 2D state-delayed stochastic systems with randomly occurring uncertainties and nonlinearities
2013
This paper is concerned with the state feedback control problem for a class of two-dimensional (2D) discrete-time stochastic systems with time-delays, randomly occurring uncertainties and nonlinearities. Both the sector-like nonlinearities and the norm-bounded uncertainties enter into the system in random ways, and such randomly occurring uncertainties and nonlinearities obey certain mutually uncorrelated Bernoulli random binary distribution laws. Sufficient computationally tractable linear matrix inequality–based conditions are established for the 2D nonlinear stochastic time-delay systems to be asymptotically stable in the mean-square sense, and then the explicit expression of the desired…
Control of Production-Distribution Systems under Discrete Disturbances and Control Actions
2011
This paper deals with the robust control and optimization of production-distribution systems. The model used in our problem formulation is a general network flow model that describes production, logistics, and transportation applications. The novelty in our formulation is in the discrete nature of the control and disturbance inputs. We highlight three main contributions: First, we derive a necessary and sufficient condition for the existence of robustly control invariant hyperboxes. Second, we show that a stricter version of the same condition is sufficient for global convergence to an invariant set. Third, for the scalar case, we show that these results parallel existing results in the set…