Frequency regulation of a RES integrated power system with AC/DC parallel link employing a fuzzy tuned fractional order controller

This paper demonstrates the operational efficacy of a newly proposed fuzzy tuned fractional order controller to offer an improved frequency regulation of a multi area renewable energy source (RES) integrated nonlinear power system. The effect of governor dead band nonlinearity and generation rate constraint of hydro and thermal power plants are considered in the system. Moreover, a proposed appropriate High voltage direct current (HVDC) tie line model is incorporated in this work, to verify the frequency deviation. Different test cases are applied to verify the robustness of the controllers on frequency response. The superiority of the proposed controller upon Proportional integral and derivative (PID), fuzzy logic controller and fuzzy PID controller in minimizing frequency deviation has been verified through MATLAB SIMULINK environment.

Extended state observer based fractional order controller design for integer high order systems

In this paper, based on the extended state observer (ESO) and on a fractional order controller (FOC), composed of an integer order PID cascaded with a fractional order filter (FOF), a new control scheme for an n th order integer plant is proposed. The ESO is used to estimate and cancel the unknown internal dynamics and the external disturbance. Afterwards, an FOC is designed to resolve the set-point tracking problem. An analytical and systematic method is proposed to design the FOC. This method is based on the Internal Model Control (IMC) and the Bode’s Ideal Transfer Function (BITF). Therefore, the proposed control structure improves the robustness and performance of the traditional linear active disturbance rejection control (LADRC), especially for the open-loop gain variation. In addition, since the system be controlled is an n th order, a general form of the BITF is also proposed. Numerical simulations on a nonlinear model and experimental results on a cart-pendulum system design illustrate the effectiveness of the suggested ESO-PID-FOF scheme for the disturbance rejection, the set-point tracking and robustness. A comparison with the results obtained using the standard LADRC is also presented.

OPTIMAL TUNING OF FRACTIONAL ORDER CONTROLLER USING WOUND HEALING ALGORITHM BASED ON CLONAL SELECTION PRINCIPLE

Fractional-order PID (FOPID) controller is a generalization of standard PID controller using fractional calculus. Compared to PID controller, the tuning of FOPID is more complex and remains a challenge problem. This paper focuses on the design of FOPID controller using wound healing algorithm (WHA) based on clonal selection principle. The tuning of FOPID controller is formulated as a nonlinear optimization problem, in which the objective function is composed of overshoot, steady-state error, raising time and settling time. WHA algorithm, a newly developed evolutionary algorithm inspired by human immune system, is used as the optimizer to search the best parameters of FOPID controller. The designed WHA-FOPID controller is applied to various systems. Numerous numerical simulations and comparisons with other FOPID/PID controllers show that the WHA-FOPID controller can not only ensure good control performance with respect to reference input but also improve the system robustness with respect to model uncertainties.

Variable fractional order sliding mode control for seismic vibration suppression of building structure

Constant fractional order vibration control strategy has been one of research hotspots in recent decades. However, the variable fractional order control method is seldom concerned up to now. In this article, a novel variable fractional order sliding mode control (VOSMC) method is proposed to suppress the responses of building structure caused by seismic excitations, including El Centro, Hachinohe, Northridge, and Kobe earthquakes. Based on the proposed variable fractional order sliding mode surface, the control law of VOSMC is presented. The global asymptotic stability of the control system is analyzed and proved by utilizing variable fractional order Lyapunov stability theorem. Besides, the corresponding constant fractional order sliding mode control (COSMC) method is also given. The control effects of VOSMC and COSMC methods are discussed by four performance indices. Finally, the utilizability and reasonability of the proposed control method is verified by using two examples (include two-story and five-story shear buildings). Compared with the COSMC method, the proposed variable fractional order controller not only has a lesser control output, but also has a higher utilization of the output, which is conducive to energy saving.

Digital Twin-Based Fractional Order Controller Optimization for Industrial Robot

In this paper, a practical and systematic tuning procedure for fractional order controller using particle swarm algorithm (PSO) based on digital twin (DT) system of industrial robot has been developed. The procedure includes a virtual realization of control system based on digital twin concept. Then a particle swarm algorithm is introduced to optimize the five parameters of the cascade fractional order PI-PIλ controller. The optimization procedure using particle swarm algorithm based on digital twin concept is also presented. Finally, the virtual industrial robot model in digital twin is simulated to verify the applicability of the optimization method. The effectiveness of using the cascaded fractional order PI-PIλ controller compared to the cascaded integer order PI-PI controller is illustrated by the simulation results, where the cascaded fractional order PI-PIλ controller responses faster with smaller tracking error over the integer order one.