A Distributed Hierarchical Control Framework for Economic Dispatch and Frequency Regulation of Autonomous AC Microgrids

Motivated by the single point of failure and other drawbacks of the conventional centralized hierarchical control strategy, in this paper, a fully distributed hierarchical control framework is formulated for autonomous AC microgrids. The proposed control strategy operates with a distinct three-layer structure, where: a conventional droop control is adopted at the primary layer; a distributed leaderless consensus-based control is adopted at the secondary layer for active power and, hence, frequency regulation of distributed generating units (DGUs); and the tertiary layer is also based on the distributed leaderless consensus-based control for the optimal power dispatch. Under the proposed strategy, the three constituent control layers work in a coordinated manner. Not only is the load dispatched economically with a negligible power mismatch, but also the frequencies of all the DGUs are regulated to the reference value. However, the frequency regulation is achieved without requiring any central leader agent that has been reported in the contemporary distributed control articles. As compared to the conventional centralized hierarchical control, the proposed strategy only needs local inter-agent interaction with a sparse communication network; thus, it is fully distributed. The formulated strategy is tested under load perturbations, on an autonomous AC microgrid testbed comprising both low-inertia-type (inverter-interfaced) and high-inertia (rotating)-type DGUs with heterogeneous dynamics, and found to successfully meet its targets. Furthermore, it can offer the plug-and-play operation for the DGUs. Theoretical analysis and substantial simulation results, performed in the MATLAB/Simulink environment, are provided to validate the feasibility of the proposed control framework.

Shape Optimization Framework for the Path of the Primary Compliance Vector in Compliant Mechanisms

The primary compliance vector (PCV) captures the dominant kinematic behavior of a compliant mechanism. Its trajectory describes large deformation mechanism behavior and can be integrated in an optimization objective in detailed compliant mechanism design. This paper presents a general framework for the optimization of the PCV path, the mechanism trajectory of lowest energy, using a unified stiffness characterization and piecewise curve representation. We present a meaningful objective formulation for the PCV path that evaluates path shape, location, orientation, and length independently and apply the framework to two design examples. The framework is useful for design of planar and shell compliant mechanisms that traverse a specified mechanism trajectory and that are insensitive to load perturbations.

Design of a discrete PID controller based on identification data for a simscape buck boost converter model

<span>This work shows the design and tuning procedure of a discrete PID controller for regulating buck boost converter circuits. The buck boost converter model is implemented using Simscape Matlab library without having to derive a complex mathematical model. A new tuning process of digital PID controllers based on identification data has been proposed. Simulation results are introduced to examine the potentials of the designed controller in power electronic applications and validate the capability and stability of the controller under supply and load perturbations. Despite controller linearity, the new approach has proved to be successful even with highly nonlinear systems. The proposed controller has succeeded in rejecting all the disturbances effectively and maintaining a constant output voltage from the regulator.</span>

Dynamic and Stability Analysis of Wind-Diesel-Generator System With Intelligent Computation Algorithm

In this chapter, the dynamic performance of a wind-diesel-generator system has been studied against wind and load perturbations. The wind perturbation is modeled by simulating base, ramp, gust, and random wind. An optimized cascade tilt-integral-derivative (CC-TID) controller is provided to the test system for producing desired control signal to regulate the blade pitch angle of wind turbine. To confirm the efficacy of CC-TID controller, the output results are compared to that of PI- and PID-controller. The optimum gains of the proposed controllers are explored employing Levy-embedded grey wolf optimization, whale optimization algorithm, drone squadron optimization, and search group algorithm. To show the effectiveness, the output results are compared to the results of genetic algorithm and particle swarm optimization tuned controllers. A thyristor control series compensator (TCSC) is provided to WDG model for increasing the damping of system oscillations. Analysis of the presented results confirm the supremacy of CC-TID-TCSC controller over other controllers provided in this chapter.

Control of a DC-DC Buck Converter through Contraction Techniques

Reliable and robust control of power converters is a key issue in the performance of numerous technological devices. In this paper we show a design technique for the control of a DC-DC buck converter with a switching technique that guarantees both good performance and global stability. We show that making use of the contraction theorem in the Jordan canonical form of the buck converter, it is possible to find a switching surface that guarantees stability but it is incapable of rejecting load perturbations. To overcome this, we expand the system to include the dynamics of the voltage error and we demonstrate that the same design procedure is not only able to stabilize the system to the desired operation point but also to reject load, input voltage, and reference voltage perturbations.

Control of a DC-DC Buck Converter through Contraction Techniques

Reliable and robust control of power converters is a key issue in the performance of numerous technological devices. In this paper we show a design technique for the control of a DC-DC buck converter with a switching technique that guarantees not only good performance but also global stability. We show that making use of the contraction theorem in the Jordan canonical form of the buck converter, it is possible to find a switching surface that guarantees stability but it is incapable of rejecting load perturbations. To overcome this, we expand the system to include the dynamics of the voltage error and we demonstrate that the same design procedure is not only able to stabilize the system to the desired operation point but also to reject load, input voltage and reference voltage perturbations.

Automatic generation control of a two area power system implementing IDDF controller under restructured environment

This paper presents the Automatic generation control of an interlinked power system in a restructured environment. The model consists of a hydro plant, a thermal plant and a diesel plant incorporated in both areas. The Area Control Error (ACE) is minimized with the help of a new controller called the Integral Double Derivative controller (IDDF) employed as a secondary controller in the proposed model. The controller parameters are optimized by a novel optimization scheme called the Lightning Search Algorithm. The proposed model is simulated under two market scenarios. The robustness of the system is also examined under step load perturbations, random loading conditions and parameter variation. The settling time of the IDDF controller is put to comparison with the PID controller and the supremacy is established.