Inertia

About: Inertia is a research topic. Over the lifetime, 12006 publications have been published within this topic receiving 164291 citations.

The Application of Microgrids Based on Droop Control With Coupling Compensation and Inertia

Abstract: A novel droop control with coupling compensation and inertia is proposed for a microgrid to achieve high dynamic performance and stability of distributed generation units. The coupling compensation scheme consists of angular frequency deviation compensation and voltage deviation compensation. They can reduce the influence of uncontrolled power coupling. The inertia scheme consists of angular frequency inertia and voltage inertia. They can slow down the change rates of the angular frequency and voltage and reduce their fluctuation magnitudes. The combination of this novel droop control method and virtual impedance can help achieve accurate power sharing. An improved particle swarm optimization (PSO) algorithm with multiswarm and multivelocity (MMPSO) is also proposed to optimize the parameters of the coupling compensation and inertia with high precision and high reliability. A simulated model and experiment platform of a microgrid are set up for testing, and the simulation and experimental results validate the excellent performance of the MMPSO and the effectiveness of the novel droop control method.

Design, test and model of a hybrid magnetostrictive hydraulic actuator

Abstract: The basic operation of hybrid hydraulic actuators involves high frequency bi-directional operation of an active material that is converted to uni-directional motion of hydraulic fluid using valves. A hybrid actuator was developed using magnetostrictive material Terfenol-D as the driving element and hydraulic oil as the working fluid. Two different lengths of Terfenol-D rod, 51 and 102 mm, with the same diameter, 12.7 mm, were used. Tests with no load and with load were carried out to measure the performance for uni-directional motion of the output piston at different pumping frequencies. The maximum no-load flow rates were 24.8 cm3 s−1 and 22.7 cm3 s−1 with the 51 mm and 102 mm long rods respectively, and the peaks were noted around 325 Hz pumping frequency. The blocked force of the actuator was close to 89 N in both cases. A key observation was that, at these high pumping frequencies, the inertial effects of the fluid mass dominate over the viscous effects and the problem becomes unsteady in nature. In this study, we also develop a mathematical model of the hydraulic hybrid actuator in the time domain to show the basic operational principle under varying conditions and to capture phenomena affecting system performance. Governing equations for the pumping piston and output shaft were obtained from force equilibrium considerations, while compressibility of the working fluid was taken into account by incorporating the bulk modulus. Fluid inertia was represented by a lumped parameter approach to the transmission line model, giving rise to strongly coupled ordinary differential equations. The model was then used to calculate the no-load velocities of the actuator at different pumping frequencies and simulation results were compared with experimental data for model validation.

Friction compensation using adaptive non-linear control with persistent excitation

Abstract: Non-linear frictional dynamics reduce the tracking performance of machine control systems involving high-precision, low-velocity tasks. We present an adaptive non-linear friction compensation scheme for a friction model, which captures problematic friction effects such as Stribeck effect, hysteresis, stick-slip limit cycling, pre-sliding displacement and rising static friction. We show that without robust adaptation, frictional dynamics and other modelling uncertainties can cause an adaptive friction compensation scheme to become unstable. We extend robust adaptive theory to include a new type of error model with a non-linear regression vector and Lipschitz disturbances. By using persistent excitation in the desired trajectory, our controller achieves stable adaptation for friction force effects due to static, Coulomb and viscous components, as well as for inertia and the Stribeck effects, while remaining robust to perturbations in friction force due to frictional lag and frictional memory. Although the S...