An Optimal Control Scheme for Load Bus Voltage Regulation and Reactive Power-Sharing in an Islanded Microgrid

This paper presents an optimal control scheme for an islanded microgrid (MG), which performs reactive power-sharing and voltage regulation. Two-fold objectives are achieved, i.e., the load estimation strategy, firstly, approximates the MG’s impedance and transmits this information through a communication link. Based on approximated impedance information, an optimal regulator is then constructed to send optimal control commands to respective local power controllers of each distributed generation unit. An optimal regulator is a constraints optimized problem, mainly responsible to restore the buses’ voltage magnitudes and realize power-sharing proportionally. The important aspect of this control approach is that the voltage magnitude information is only required to be transferred to each inverter’s controller. In parallel, a secondary control layer for frequency restoration is implemented to minimize the system frequency deviations. The MATLAB/Simulink and experimental results obtained under load disturbances show the effectiveness for optimizing the voltage and power. Modeling and analysis are also verified through stability analysis using system-wide mathematical small-signal models.

SYNTHESIS OF A TRACKING CONTROL SYSTEM OVER THE FLOTATION PROCESS BASED ON LQR-ALGORITHM

The studies are devoted to the synthesis of the tracking control system of the flotation process based on the LQR-algorithm. The algorithm of finding the parameters of the optimal regulator is given. The results of modelling of the system with the regulator are obtained, and also the comparative analysis of the results of modelling of the system with and without the regulator is shown, which is performed with the help of Matlab software package and the Simulink toolkit.

Optimal vibration control of moving-mass beam systems with uncertainty

A linear optimal regulator for uncertain system is designed through the application of the probability density evolution method to linear quadratic regulator controller. One important background of this work is bridge-vehicle/gun-projectile system. This type of optimal problem is currently transformed into a moving load problem. The developed optimal regulator can provide the law of probability densities of outputs varying with time. In order to make the advocated method reach an optimal performance, the beneficial weighting matrix pair (Q, R) is selected using a trade-off sense. The designed regulator is then applied to a coupled simply supported beam-moving mass system, choosing the mid-span deflection as an output response and considering stochastic system parameters. The numerical example shows that the robustness of the proposed optimal regulator cannot be overestimated in comparison with a deterministic linear quadratic regulator controller. Further, the proposed method can produce an efficient solution channel for modern optimal control theory, especially, when compared with different uncertain optimal control techniques.

Compare of Transient Quality in Automatic Control Systems with Classic PID Algorithm and Optimal Regulator

Currently, about 90–95% of generic controllers use the PID algorithm to generate control actions, while 64% of the PID controllers are used in single-circuit automatic control systems. Most of industries (power industry among them) use hundreds of automatic control systems. The quality of their work is the basis of economic efficiency of technical processes, ensuring safety, reliability, durability and environmental friendliness of both technological equipment and automation equipment. There are different modifications of PID-controller structure implementation. In practice the ideal PID controller with a filter and the classic PID regulator (serial connection of the ideal PI controller and the real PD regulator as the direct action elements) are widely used. The problem of choosing a rational structure and a method of parametric optimization of PID controllers, which provide the best direct indicatives of the quality in the development of the main effects in single-circuit automatic control systems, becomes urgent. However, only for the classical PID controllers, which are widely used at present, there are more than three hundred methods for adjusting the three parameters of the optimal dynamic adjustment, as well as the ballast time constant. This results in arising a problem of substantiation of the best structure and method of parametric optimization of classical PID regulators. As a basic option, one of the simplest and most obvious one, viz. the method of automated adjustment of the controller in the Simulink MatLab environment had been chosen, which was compared with the method of full compensation in general for objects with a transfer function in the form of an inertial link with a conditional delay. Two variants of control action realization on the basis of the structural scheme of the optimal regulator developed by the Belarusian national technical University were also offered. In contrast with the classic PID controller, the optimal controller has one parameter of dynamic adjustment setting. The results of simulation of transients at basic perturbations confirmed that the best direct indicatives of the quality are provided with an optimal regulator, which makes it possible to recommend it for wide implementation instead of the classic PID controllers.

Simulation of Performance Response of State Variables of a Chemical Boiler Process

This paper has presented simulation of performance response of state variables of a chemical boiler process. The transfer function of a boiler flow control process of a chemical plant was obtained. The transfer function was transformed into state space form to study the state variables of the system. An optimal regulator was designed using MATLAB programme. The developed optimal regulator was added to the loop of the system to form a closed loop system. A Simulink model was developed and used to study performance response of the system. Simulation was carried out for two conditions, open loop and closed loop. The simulation results indicated that the performance responses of the state variables were improved and better stability achieved with the inclusion of the designed feedback gain matrix of the optimal regulator.