This paper considers the dynamic anti-windup design problem for linear systems with time-varying state delay, input saturations and external disturbances. A dynamic anti-windup compensator is first designed that is dependent on the upper bound of the time-varying delay. Then, using an augmented Lyapunov–Krasovskii functional, a distributed-delay-dependent sector condition, some advanced inequalities and some congruence transformations, sufficient conditions are established under which the state trajectories of the closed-loop systems are bounded and meanwhile, the performance can be guaranteed. The anti-windup compensator gain can be explicitly solved by means of linear matrix inequalities. For the case of constant delay, the corresponding result is also presented. Finally, two numerical examples illustrate the effectiveness and advantages of the proposed results.

Dynamic anti-windup design for linear systems with time-varying state delay and input saturations

Nowadays, vehicles are being fitted with systems that improve their maneuverability, stability, and comfort in order to reduce the number of accidents. Improving these aspects is of particular interest thanks to the incorporation of autonomous vehicles onto the roads. The knowledge of vehicle sideslip and roll angles, which are among the main causes of road accidents, is necessary for a proper design of a lateral stability and roll-over controller system. The problem is that these two variables cannot be measured directly through sensors installed in current series production vehicles due to their high costs. For this reason, their estimation is fundamental. In addition, there is a time delay in the relaying of information between the different vehicle systems, such as, sensors, actuators and controllers, among others. This paper presents the design of an $${H}_{\infty }$$
 -based observer that simultaneously estimates both the sideslip angle and the roll angle of a vehicle for a networked control system, with networked transmission delay based on an event-triggered communication scheme combined with neural networks (NN). To deal with the vehicle nonlinearities, NN and linear-parameter-varying techniques are considered alongside uncertainties in parameters. Both simulation and experimental results are carried out to prove the performance of observer design.

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Event-triggering $${H}_{\infty }$$ H ∞ -based observer combined with NN for simultaneous estimation of vehicle sideslip and roll angles with network-induced delays

This paper proposes a sliding mode control (SMC) approach to design $$H_{\infty }$$
 performance-based load frequency controller for interconnected power system (IPS) with time delay. Incorporating an artificial delay, a sliding surface function is designed to enhance dynamic performance of the power system. Linear matrix inequality-based stabilization criterion is derived using Lyapunov–Krasovskii functional for multi-area power system. A novel SMC law is designed with artificial delay to drive the system trajectory into the predefined sliding surface. The applicability of the proposed controller is proved by considering a two-area time-delay IPS. Performance of the controller is verified from the simulation study of the time-delay IPS with proposed controller in MATLAB/Simulink. Then, the controller performance is verified in real time by using OPAL-RT OP4510 digital simulator.

$$H_{\infty }$$ H ∞ Performance-Based Sliding Mode Control Approach for Load Frequency Control of Interconnected Power System with Time Delay

The stability problem of discrete-time linear systems with interval time-varying delays is investigated in this paper. According to the latest summation inequality technique, an improved free-matrix-based summation inequality is proposed in this paper. In order to make full use of the improved inequality to bound the upper bounds of the difference Lyapunov-Krasovskii functional (LKF), an augmented LKF with some extra status information is constructed. A new delay-range-dependent stability criterion is derived in the form of linear matrix inequalities (LMIs) via the modified LKF approach. The criterion is less conservative than some existing results. Finally, some standard numerical examples are presented the effectiveness of the proposed approach.

Enhanced Stability Criteria for Discrete-time Systems with Time-varying Delay

In this paper, an internal model control based anti-windup compensator (AWC) is designed for nonlinear systems subjected to time-varying delay and input saturation. By using Lyapunov Krasvoskii Fun...

Design of nonlinear anti-windup compensator for time-delayed systems based on triple Lyapunov Functional:

In this paper, a delay-dependent anti-windup compensator is designed for wide-area power systems to enhance the damping of inter-area low-frequency oscillations in the presence of time-varying delays and actuator saturation using an indirect approach. In this approach, first, a conventional wide-area damping controller is designed by using H&#x221E output feedback with regional pole placement approach without considering time-varying delays and actuator saturation. Then to mitigate the effect of both time-varying delays and actuator saturation, an add-on delay-dependent anti-windup compensator is designed. Based on generalized sector conditions, less conservative delay-dependent sufficient conditions are derived in the form of a linear matrix inequality &#x0028 LMI &#x0029 to guarantee the asymptotic stability of the closed-loop system in the presence of time-varying delays and actuator saturation by using Lyapunov-Krasovskii functional and Jensen integral inequality. Based on sufficient conditions, the LMI-based optimization problem is formulated and solved to obtain the compensator gain which maximizes the estimation of the region of attraction and minimizes the upper bound of L2-gain. Nonlinear simulations are performed first using MATLAB &#x002F Simulink on a two-area four-machine power system to evaluate the performance of the proposed controller for two operating conditions, e.g., 3-phase to ground fault and generator 1 terminal voltage variation. Then the proposed controller is implemented in real-time on an OPAL-RT digital simulator. From the results obtained it is verified that the proposed controller provides sufficient damping to the inter-area oscillations in the presence of time-varying delays and actuator saturation and maximizes the estimation of the region of attraction.

A delay-dependent anti-windup compensator for wide-area power systems with time-varying delays and actuator saturation

In this study, a delay-dependent anti-windup compensator (AWC) is designed for supplementary damping control (SDC) of flexible AC transmission system (FACTS) device to enhance the damping of inter-area oscillations of the power system subjected to time-delay and actuator saturation. By employing global signal measurements, an SDC of FACTS device is designed without considering the effect of time-delay and actuator saturation to stabilise the power system using a robust output feedback controller with pole placement approach. Then, based on the generalised sector condition and Lyapunov–Krasovskii functional, an add-on delay-dependent AWC is designed to mitigate the adverse effect of time-delay and actuator saturation non-linearity. For the design of delay-dependent AWC, sufficient conditions guarantee the asymptotic stability of the closed-loop power system are formulated in the form of linear matrix inequalities (LMIs). These conditions are cast into the LMI-based convex optimisation problem to compute the AWC gains. To evaluate the effectiveness of the proposed controller, non-linear simulations were performed first using MATLAB/Simulink. Then, the authors implemented the proposed controller in real-time using the Opal-RT digital simulator. From the obtained results, it is observed that the proposed controller enhances the damping of inter-area oscillations by compensating the effect of time delay and actuator saturation.

Anti-windup compensator design for power system subjected to time-delay and actuator saturation

In this paper, a dynamic output feedback controller designed for damping enhancement of inter-area oscillations using wide-area signals as their feedback signals. The packet-based communication network is used to transfer wide-area signals. Communication network constraints such as networked induced delays, packet dropouts, and packet disorder are captured in the closed-loop power system by constructing as networked control system (NCS) model. Stabilization of closed-loop system with aforesaid problems have been formulated as the delay-dependent control problem. Sufficient conditions for the design of a dynamic controller are formulated in form of linear matrix inequalities by using quadratic Lyapunov criterion. In addition to the dynamic controller, a robust pole placement approach is applied to place the closed-loop poles in the prescribed stability region. Nonlinear simulations on a case study namely a two-area four-machine power system is performed to evaluate the performance of the proposed controller and its performances are compared with power oscillation damping (POD) controller and H ∞ controller.

Robust damping controller design for damping enhancement of inter-area oscillations considering communication network constraints

The present work aims at comparison between Internal Model Control (IMC) and Multiobjective Output Feedback Controller. The inter model control (IMC) based tuning principle is straightforward, simple to use, and easy to implement which is exceptionally appealing to professionals in the real practice. The most essential reality is IMC-PI/PID tuning guideline has one and only characterized tuning parameter, which is straightforwardly identified with the closed loop time constant. Internal Model Control selecting among the other conventional PID Controllers by considering values of the Integral of the squared value of the error (ISE) and Integral of the absolute value of the error (IAE). IMC is comparing with Direct Synthesis Method (DSM) this method is based on the desired closed loop characteristic equation. In Multiobjective the design objectives are H-infinity and Pole Placement Constraints. These design objectives are formulated in terms of the common lyapunov function. A complete Linear Matrix Inequality (LMI) of the output feedback synthesis with H-infinity control with pole placement is presented. By change of controller variables the output feedback control would be linearized due to the nonlinear terms include in the objectives constraints. The Linear Matrix Inequality (LMI) constraints of the design objectives i.e. H-infinity and Pole Placement Constraints are derived, and these LMI constraints are solving by using LMI Solvers. The comparison of the methods is illustrated by a realistic design example and the simulation results are presents.

Maddela Chinna Obaiah

Papers

A delay-dependent anti-windup compensator for wide-area power systems with time-varying delays and actuator saturation

Anti-windup compensator design for power system subjected to time-delay and actuator saturation

Robust damping controller design for damping enhancement of inter-area oscillations considering communication network constraints

Multiobjective output feedback controller compare with IMC-based PID controller

Stabilisation of wide-area supplementary damping controller of TCSC via an improved integral inequality approach