Search results for "Stability"
showing 10 items of 3085 documents
Mathematical modelling of an inverter-based distributed generator
2016
In this paper, a modeling approach of a three phase power inverter based on an electrostatic synchronous machine is presented. By the proposed approach, any inverter-based distributed generator in a microgrid can be replaced by an equivalent electrostatic machine. This paper aims to promote the use of the proposed modeling approach in the analysis of microgrid stability. Thanks to the proposed modeling approach, transient performances of on-grid operation of converter-based distributed generators could be easily analyzed by multi-machine models. Parameters of the equivalent synchronous electrostatic machine model are derived to achieve equivalence with the inverter model. Small signal model…
Hold design supports learning and transfer of climbing fluency
2014
Being a discipline with a broad range of genres, rock climbing is an activity where participants seek to generalize the skills they learn in different performance contexts. A training strategy for achieving skill transfer was explored in a group of experienced climbers. Specifically, we tested the effect of practising on three routes, each of the same difficulty, but where handholds supported opportunities for using either a single technical action or multiple actions. Transfer of climbing fluidity in terms of the geometric index of entropy (GIE) of the hip trajectory was then assessed. We expected that learning would be induced on the route where multiple actions were usable. Results revea…
Modeling Round Robin Test: An Uncoupled Approach
2014
Abstract The solution of the modeling test presented in the paper is based on an uncoupled hydro-mechanical approach. Firstly, the controlled infiltration process is modeled by a finite element transient groundwater seepage software. Afterwards, calculated pore water pressures at successive instants are used for the slope stability analysis. Time evolution of the slope stability is analysed by using the infinite slope model, according to the classical limit equilibrium method.
Obtaining dynamic Norton parameters of a solar panel from manufacturer data
2016
Photovoltaic arrays have been shown to possess significant influence on the dynamic performance of coupled source-converter-load system while its dynamic resistance is the most important parameter, contributing to the overall system dynamics. In this paper, a method of deriving the parameters of linearized photovoltaic equivalent circuit from manufacturer data is proposed. The approach allows predicting the range of dynamic Norton parameters for the expected irradiation and temperature operation conditions thus defining clear bounds required for robust design of the system controller.
Control of the Biodegradation of Mixed Wastes in a Continuous Bioreactor by a Type-2 Fuzzy Logic Controller
2009
Abstract Type-2 fuzzy logic control is proposed for nonlinear processes characterized by bifurcations. A control simulation study was conducted for a bioreactor with cell recycle containing phenol and glucose as carbon and energy sources in which a pure culture of Pseudomonas putida is carried out. The model developed by Ajbar [Ajbar, A. (2001). Stability analysis of the biodegradation of mixed wastes in a continuous bioreactor with cell recycle. Water Research, 35 (5), 1201–1208] was used for the simulations. The particular dynamics of the bioreactor, characterized by two saddle-node bifurcations, makes its control difficult, since it may become unstable also for small variations of some p…
Nonlinear Control of a Pneumatic Muscle Actuator System
2001
Abstract The performance of a Pneumatic Muscle Actuator under three tracking control strategies is compared: robust backstepping, sliding-mode and gain scheduling. Robustness is assured for the three controllers in the presence of model uncertainties and external perturbations. Exponential stability is proved for the sliding-mode tracking controller, ultimate boundedness for the backstepping tracking controller and exponential stability for constant or slowly-varying reference signals for the gain scheduling controller. Computer simulations show a good performance for the tracking of a sine wave by the first two controllers, although the sliding-mode strategy yields a high-frequency switchi…
Partial stability for specific growth rate control biotechnological fed-batch processes
2004
In this paper, the problem of the specific growth rate control in biological reactions in fed-batch mode is dealt with. It is assumed that only part of the state is measurable on-line, namely biomass and volume. Moreover, no estimation of the specific growth rate is used. An unbounded manifold is tracked using a partial state feedback. Then, techniques for partial stability, i.e., only with respect to part of the variables, are used in order to analyze the problem.
Reassessment of voltage stability for distribution networks in presence of DG
2016
There is a growing interest in integrating renewable energy based distributed generation (DG) in the electrical power distribution networks. The installation of DG units at distribution level impacts critically the planning and operation characteristics of the network. The type, location, number and capacity of the integrated DGs affects system behavior and performance. In this paper the effect of installing new DGs on the distribution network voltage stability is studied. The optimal location of the newly installed DGs are decided based on the Power Stability Index (PSI) and Voltage Stability Index (VSI). Moreover, Voltage Stability Margin (VSM) of the interconnected DG distribution networ…
Fuzzy control for Electric Power Steering System with assist motor current input constraints
2015
Abstract Friction and disturbances of the road are the main sources of nonlinearity in the Electric Power Steering (EPS) System. Consequently, conventional linear controllers design based on a simplified linear model of the EPS system will result in poor dynamic performance or system instability. On the other hand, a brush-type DC motor is more used in EPS control with an input current that is limited in practice. The control laws designed without taking into account the saturation effect may have undesirable consequences on the system stability. In this paper, a Takagi–Sugeno (T−S) fuzzy is used to represent the nonlinear behavior of an EPS system, and stabilization conditions for nonlinea…
Stability and Noises Evaluation of Fuzzy Kalman UAV Navigation System.
2009
In this paper a new Fuzzy/Kalman navigation system for Unmanned Aerial Vehicles (UAV) is presented. A closed loop velocity Fuzzy navigation system is proposed for stabilizing the UAV in a reference trajectory generated dynamically and for obtaining a forward velocity command. The Kalman's filter (KF) is included in the feedback line of the fuzzy control system to filter the internal noise of the sensors and to evaluate the external noise due to possible perturbations of the nominal motion. The efficiency of the navigation system has been shown through experimental tests in a Matlab environment.