The proper and sustainable performance of any electrical system is mainly related to the designers' insight into the nature of that system. Therefore, the need to provide an accurate model based on the actual behavior of the system has considerable importance. In the case of inverter-based microgrid, due to the lack of sufficient synchronizing torque, the design process must be carried out with the utmost precision. In this paper, the stability of the inverter-based microgrid will be studied. First by presenting the equations of the microgrid components its state-space model is obtained and in the presence of the static LOAD model the stability of the system will be investigated. Then, by placing the inventory of DYNAMIC exponential recovery and static polynomial LOAD models, the results of the static model-based design are investigated. In this study, the measure of system stability will be eigenvalue plots and system performance. In order to achieve system stability and performance improvement, the state variables participation factors extracted and the effective parameters will be studied.

In this article, the analysis of a simply supported viscoelastic Bernoulli beam under a DYNAMIC transverse LOADing combined with a compressive axial LOAD was discussed. The applied DYNAMIC transverse LOAD was considered a non-harmonic LOAD with an exponential decreasing function over time, and the applied axial LOAD was considered constant compressive. This study investigated the effect of a specific decreasing transverse LOAD and introduced, formulated, and proved the phenomenon of non-harmonic resonance of the viscoelastic beam, for the first time. The stress-strain relationship of the linear viscoelastic material was expressed according to the Boltzmann integral law. The relaxation function of the viscoelastic material was defined based on two terms of the Prony series. The displacement field was approximated by the product of two functions, a known spatial function and a time function with unknown coefficients. Using the principle of virtual work, the formulation of the viscoelastic beam was extracted. Then, utilizing the Laplace transform, the unknown coefficients of the time function were calculated. Finally, the displacement field of the viscoelastic beam was expressed in the time and space domains. To validate the results, Abaqus software was used for beam modeling. In the numerical results section, the effect of different viscoelastic material parameters and different LOADs on the displacement of the viscoelastic beam was investigated. Also, the occurrence time of the non-harmonic resonance, and the ratio of the maximum displacement at the resonance time to the displacement at time zero were calculated

The autonomous microgrid can incur a stability issue due to the low inertia offered by power electronics-based distributed generating sources of the microgrid. Due to the fast DYNAMICs of inverters and the intermittent nature of renewables, the first phase of abrupt LOAD change might not be shared evenly by DGs, and the system's stability deteriorates substantially. Hence the stability of the microgrid can greatly influenced by the LOAD DYNAMICs because of the inertialess generating sources. This paper presents a stability analysis of microgrid considering passive, active, and DYNAMIC LOADs fed by inverter-based DGs. The small-signal analysis demonstrates the effect of inverter parameters and LOAD factors. The dominance of states in oscillatory mode is examined by participation analysis. The results show that passive LOAD does not introduce low-frequency mode, whereas rectifier interfaced active LOAD (RIAL) introduces low-frequency mode due to DC voltage controller. The induction motor (IM) LOAD introduces less damped eigenvalues in the microgrid and profoundly affects the real power-sharing of the system. The time-domain results verify the results obtained through eigenvalue analysis.

In this paper, a general formula for finding the Maximum Allowable DYNAMIC LOAD (MADL) of geometrically nonlinear flexible link manipulators is presented. The DYNAMIC model for links in most mechanisms is often based on the small deflection theory but for applications like lightweight links, high-precision elements or high speed it is necessary to capture the deflection caused by nonlinear terms. First, the equations of motion are derived; taking into account the nonlinear strain displacement relationship using Finite Element Method (FEM) approaches. The maximum allowable LOADs that can be achieved by a mobile manipulator during a given trajectory are limited by a number of factors. Therefore, a method for determination of the DYNAMIC LOAD carrying capacity for a given trajectory is explained, subject to the accuracy, actuator and amplitude of residual vibration constraints and by imposing a maximum stress limitation as a new constraint. In order to verify the effectiveness of the presented algorithm, two simulation studies considering a flexible two-link planar manipulator mounted on a mobile base are presented and the results are discussed. The simulation results indicate that the effect of introducing geometric elastic nonlinearities and inertia nonlinearities on the maximum allowable LOADs of a manipulator.

In this paper, a nonlinear optimal feedback control law is designed to find the maximum LOAD carrying capacity of mobile manipulators for a given trajectory task. The optimal state feedback law is given by the solution to the nonlinear Hamilton-Jacobi-Bellman (HJB) equation. An iterative procedure is used to find a sequence of approximate solutions of the HJB equation. This is done by solving a sequence of Generalized HJB (GHJB) differential equations. The Galerkin procedure is applied to find a numerical solution to the GHJB equation. Using this method, a nonlinear feedback is designed for the mobile manipulator and, then, an algorithm is developed to find the maximum payLOAD. In mobile base manipulators, the maximum allowable LOAD is limited by their joint actuator capacity constraints, nonholonomic constraints and redundancy that arise from base mobility and increased Dofs. To solve the extra Dofs of the system, an extended Jacobian matrix and additional kinematic constraints are used. The validity of the methodology is demonstrated via simulation for a two-link wheeled mobile manipulator and linear tracked Puma arm and the results are discussed.

Economic dispatch at minimum production cost is one of the most important subjects in the power system operation, which is a complicated nonlinear constrained optimization problem. To solve the DYNAMIC economic dispatch problem, it is assumed that a thermal unit commitment has been previously determined. Since DYNAMIC economic LOAD dispatch was introduced, several methods have been used to solve this problem. However, all of those methods may not be able to provide an optimal solution and usually getting stuck at a local optimal.In this paper, an Improved Particle Swarm Optimizer (IPSO) has been proposed to solve DYNAMIC economic LOAD dispatch problem. This algorithm is applied to a complex DYNAMIC economic dispatch problem for 6-unit power systems with a 24-h LOAD demand at each 1-h time intervals. Comparing IPSO results with other methods' results that reported in literature shows the ability of IPSO to reach better solutions.

The purpose of this study is to present a 2-D numerical model that solves the transient equations of flow, energy and species conservation in a single tubular solid oxide fuel cell (SOFC). Also an electrical model is considered to compute the electrical potential and current distribution in the cell. Using this comprehensive model the cell DYNAMIC operation and response in a step LOAD current change is studied. The simulation starts when the cell is at the steady state in a specific output LOAD. When the LOAD step takes place, the solution continues to a secondary steady state condition. Then the cell transient behavior is analyzed. The results show that when the LOAD current is stepped up, the output voltage reduces to steady state in about 750s.