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Current power system has taken a paradigm shift from the conventional structure to the hybrid consisting of thermal and renewable energy sources (RESs), such as hydro, tidal, geothermal, etc. power generating units. However, RESs are intermittent and extremely unpredictable, thus may cause huge frequency deviations. For the smooth operation of the power system in the wake of RESs intermittency and continuously varying load demands, an robust and ameliorated load frequency control (LFC) strategy is requisite. Therefore, in this paper, a new cascade fuzzy-noninteger (fractional order) proportional derivative with filter-proportional integral (CFPDμF-PI) control policy is proposed to cope with the frequency abnormality that occurs due to the presence of renewable generating units in the existing power system. The CFPDμF-PI controller adopts FPDμF as a master and integer order PI as a slave controller. The recently introduced slime mold algorithm (SMA) is employed as a stochastic optimizer to tune the controller parameters. Two case studies have been presented to investigate the performance of the proposed controller. Case-1 simply focuses on the implementation of the proposed technique on a two-area non-reheat thermal power system while case-2 involves the two-area thermal-hydro power system. In both cases, the efficiency of the control method is validated in the presence of tidal, geothermal power plants, and solid oxide fuel cells. To affirm the contribution of our proposal, comparative studies with the existing state-of-the-art techniques have been conducted under identical conditions. From the data analysis, it is witnessed that the proposed control approach with the integration of RESs presents an advancement in the four performance indices by 75.29%, 77.79%, 90.48%, 94.68%, and 36.19%, 40.87%, 49.41%, 50% for case-1 and case-2, respectively. Different scenarios for the robustness analysis validate the capability of the proposed approach in LFC and suitability for other real-world applications. [ABSTRACT FROM AUTHOR]

Striking developments have taken place in feedback control theory after the evolution of the fractional-order (FO) control concept. However, for large-scale (high-order) systems, these well-established FO techniques become rigorous and lead to an infeasible solution. To overcome this issue, this paper proposes a three-fold control policy. The first step finds the optimal reduced-order (low-order) model using Big-Bang, Big-Crunch (BB–BC) optimisation algorithm. Based on the obtained reduced model, the control structure is formulated in the internal model control (IMC) framework. The controller acquires a PID form followed by an additional term and FO integrator. Unlike the FO-PID controller which demands five tuning parameters, the proposed controller requires only two tuning parameters whose evaluation is done on the basis of user specified gain crossover frequency and phase margin. To substantiate the design approach, a detailed simulation study has been carried out, in which the problems of tracking control, disturbance rejection, and time-delay compensation are illustrated. [ABSTRACT FROM AUTHOR]

In a feedback control loop, when there exists a delay in processing the control signal (often called computational delay), it is difficult to stabilize the system, particularly when the system exhibits uncertainty. To solve this problem, we proposed a new robust proportional integral control strategy for a class of uncertain systems exhibiting parametric uncertainty. A two-stage scheme is proposed in which the first stage identifies the worst plant that has the highest chance of facing instability; and in the second stage, based on the worst plant, the tuning parameters of the proportional integral controller are determined using the stability boundary locus approach under the desired closed-loop specifications of gain and phase margins. The efficiency of the proposed scheme is verified for servo and regulatory control problems. [ABSTRACT FROM AUTHOR]

Event-triggered control (ETC) is becoming increasingly popular in load frequency control (LFC) operation in power systems. So far, the existing literature has primarily focused on load disturbance rejection in face of communication delay without considering much on networked-induced measurement disturbances and messages sent. In this paper, we study the LFC operation as a problem of networked control system and propose, for the first time, an ETC based switching approach for frequency regulation. We derive delay-dependent conditions to obtain the lower bound on inter-event time during event-trigger mechanism which assures the robust stability under networked induced time-varying delays and measurement disturbance and reduction in the amount of sent measurements. The effectiveness of the proposed approach is verified via numerical examples based on single-, two-area power systems and single-area with electric vehicle (EV) participation. [ABSTRACT FROM AUTHOR]

This paper proposes a simple approach to design fractional-order (FO) controller via internal model control (IMC) technique for load frequency control (LFC) problem in power systems. The proposed scheme utilizes the concept of CRONE principle, model-order reduction and FO filter in IMC framework to derive a robust controller. Initially, the scheme is applied to single-area power system and then extended to two-area interconnected system. The turbines considered are non-reheated, reheated and hydro type; and physical constraints of turbine and governor are also taken into account to validate the applicability in more realistic environment. Simulation results show that it can bring improved disturbance rejection performance in nominal condition as well as in presence of uncertainties and constraints in plant parameters. [ABSTRACT FROM AUTHOR]

This paper proposes a robust fractional-order controller for DC servomotor using internal model control and CRONE (Commande Robuste d'Ordre Non Entier) principle. The controller acquires a PID (proportional-integral-derivative) form followed by a fractional-order integrator. Unlike the conventional fractional-order PID controller which demands five tuning parameters, the proposed scheme has only two tuning parameters which can be obtained on the basis of desired gain crossover frequency and phase margin. For speed control problem, the performance of the proposed controller is studied on hardware set up called precision modular servo system. The proposed controller outperforms in terms of robustness and optimality when compared with controllers designed by integer-order technique. Furthermore, the proposed scheme is applied for position control problem and validated on QUBE-Servo 2 set up. [ABSTRACT FROM AUTHOR]

This paper proposes a robust controller for a parametric uncertain system of order three. The scheme conceptualizes the approach of selecting the worst-case plant and then the controller is designed using the internal model control principle which constitutes the reduced model of worst-case plant. The beauty of the proposed approach is that even though the plant is uncertain, the complete robust stability analysis and controller design is carried out by a single linear model. As an illustrative example, a load frequency control (LFC) problem is considered for single- and multi-area power systems in presence of unexpected disturbances, parametric uncertainties and physical constraints. The proposed controller is also applied to the network topology similar to standard IEEE 39 bus system (New England 10 machine test system) to validate the more realistic LFC application. Simulation studies show that the proposed controller brings robust and fast disturbance rejection attributes. [ABSTRACT FROM AUTHOR]

In this paper, a new approach is proposed for the robust PID controller design for load frequency control (LFC) problem in a multi-area power system having different turbines. The proposed approach is based on Kharitonov’s theorem and stability boundary locus. In this paper, first of all, four-area power system model for LFC problem is presented in the form of a linear uncertain system with fixed lower and upper bounds in the coefficients. Then, stability analysis is carried out using Kharitonov’s theorem and lastly a robust controller is designed for each control area of multi-area power system. The beauty of the proposed approach is that the fixed PID controller is taking care of uncertainty in the each control area. The efficiency and efficacy of the proposed approach is tested through two examples and results are compared with few recently proposed approaches. [ABSTRACT FROM AUTHOR]

The internal model control (IMC)-based PID controller is widely used in industrial control problems. This scheme provides a good compromise among set-point tracking, disturbance attenuation, and robustness. Therefore, in this paper, we propose a simple technique to design IMC-PID controller. To illustrate the utility of the proposed technique, different types of linear and nonlinear second-order systems and approximated second-order models of higher-order systems are simulated. The proposed approach depicts quick response to set-point change, good disturbance attenuation, and optimal performances in most of the class of problems when compared to the conventional IMC-PID and other existing popular techniques. The beauty of this paper is that there is no need of highly complex mathematical approaches, and using only simple conventional IMC approach, the improved servo and regulatory results can be achieved. [ABSTRACT FROM AUTHOR]

The large-scale power systems are liable to performance deterioration due to the presence of sudden small load perturbations, parameter uncertainties, structural variations, etc. Due to this, modern control aspects are extremely important in load frequency control (LFC) design of power systems. In this paper, the LFC problem is illustrated as a typical disturbance rejection as well as large-scale system control problem. For this purpose, simple approach to LFC design for the power systems having parameter uncertainty and load disturbance is proposed. The approach is based on two-degree-of-freedom, internal model control (IMC) scheme, which unifies the concept of model-order reduction like Routh and Padé approximations, and modified IMC filter design, recently developed by Liu and Gao refid="ref24"/ . The beauty of this paper is that in place of taking the full-order system for internal-model of IMC, a lower-order, i.e., second-order reduced system model, has been considered. This scheme achieves improved closed-loop system performance to counteract load disturbances. The proposed approach is simulated in MATLAB environment for a single-area power system consisting of single generating unit with a non-reheated turbine to highlight the efficiency and efficacy in terms of robustness and optimality. [ABSTRACT FROM PUBLISHER]

To preserve frequency and tie-line power flow within a tolerable range in modern intricate and renewable energy sources (RES) integrated power system, an intelligent, expert, and robust load frequency control (LFC) scheme is requisite. This paper proposes a new load frequency control (LFC) approach using a dual-stage controller composed of fractional-order tilted-integral-derivative (TID) and integer-order proportional-derivative (PD) controllers. The recently developed salp swarm algorithm has tuned the parameters of the controller. The proposed scheme exhibits robustness and fast disturbance rejection performance because the tilted-integral-derivative controller is structured in a fractional-order framework, and transient response is improved due to the proportional-derivative controller. The overall activity of the LFC has been further upgraded by incorporating the flexible AC transmission system (FACTS) device namely thyristor-controlled phase shifter (TCPS) unit and energy storage system called redox flow battery (RFB) units. The proposed control approach is applied to diverse types of multi-area multi-source power systems with thermal, hydro, and wind turbine units along with nonlinear functions namely generation rate constraint (GRC), governor dead band (GDB), and communication delay (CD). The simulation results yield improved frequency regulation activity with and without TCPS and RFB using the proposed control approach when compared with the recently developed LFC approaches. Sensitivity analysis also established the robustness of the proposed control approach. [ABSTRACT FROM AUTHOR]

The current study endeavors to put together evolution, developments, and future prospects of internal model control strategy. Due efforts have been made to include all the techniques and philosophies used to that end. The brief account of the most recent techniques for near optimal and robust control has been provided along with a summary of conventional control schemes. At the same time, more emphasis is given on the issues in IMC design for single-input, single-output systems, like quantitative filter selection and tuning guidelines, modified structures, and related aspects of contemporary research developments. A set of references of all concerned papers, and a brief summary in them is provided. This paper also presents the results of these techniques as provided in the respective references. Illustrative example is given to show the effectiveness and the merits of the IMC based various forms. [ABSTRACT FROM AUTHOR]

Abstract—A new technique for tuning a fractional order proportional integral derivative (FOPID) controller is presented and analyzed for load frequency control of power systems. The proposed technique involves model order reduction for model simplification, internal model control for initial estimation of PID gains to formulate a compact solution space required for big bang–big crunch (BB–BC) algorithm, which ascertains optimal FOPID parameters in the search space delineated via IMC technique. The beauty of the proposed approach is that it gives an innovative way to incorporate soft computing algorithms in control applications in such a manner that leads to reduction in randomness associated with heuristic techniques. To validate the effectiveness of the proposed scheme, it is implemented on a power system comprising of reheated turbine and a realistic model of IEEE 10 machine 39 bus New England system in presence of nonlinearities. A comprehensive comparative analysis with other recent controller design techniques, conducted in terms of simulation plots, performance indices and statistical parameters is a testimony to efficacy of proposed technique. [ABSTRACT FROM AUTHOR]

Regulating the frequency fluctuations (known as load frequency control) in the power system is an important aspect that directly signifies the balance between the generation and demand. The present study proposes an optimal LFC scheme encapsulating the concept of fractional-order based tilted-integral-derivative (TID) controller having optimized parameters using the recently developed optimization technique called salp swarm algorithm. The various non-linearities such as governor dead-band, generation rate constraint, and communication time delays are also considered in the power system having thermal-hydro-wind turbines generating units in both areas. Furthermore, the impact of thyristor controlled phase shifter (TCPS) and redox flow battery (RFB) has been investigated in the proposed power system. Extensive simulations for different test systems and robustness analysis with wide variation in all system parameters at a time have been executed to validate the superiority of the proposed control strategy. The effectiveness of the proposed controller has been studied by comparing system response with recently developed algorithms. The performance evaluations confirm that the proposed controller provides stable, optimal, and superior performance compared to other existing schemes. Further, obtained results strongly suggest that TCPS and RFB units stabilize the transients quickly to enhance the system frequency stability during load instabilities. [ABSTRACT FROM AUTHOR]

In this paper, a soft computing based scheme is proposed for the model order reduction of single input-single output commensurate fractional-order (FO) systems. The fractional-order system is first converted into an integer order (IO) system. The reduced order model of the corresponding integer order system is then determined via big bang – big crunch (BBBC) optimization algorithm. Finally, the reduced IO transfer function is transferred back to its FO form through an inverse substitution. The proposed approach is substantiated by two numerical examples of different orders. The effectiveness of the technique is demonstrated by the comparison of two performance indices, i.e. integral square error (ISE) and H ∞ error and the response characteristics in time and frequency domain with the existing techniques from the literature. It is revealed that the response of the proposed BBBC based reduced order model is much closer to that of the original higher-order system. [ABSTRACT FROM AUTHOR]

Highlights • Performance prediction of SPV modules. • Predictive models include electrical equivalent models and neural networks. • Cascade implementation of 7 parameter and feed forward neural network. • MATLAB GUI developed to predict the SPV module performance. • Five I-V curve parameters determined as a function of temperature and irradiance. • Simultaneous comparison of various predictive models. • Analysis for five SPV module technologies. Abstract Before a photovoltaic (PV) system is installed, a prerequisite modelling and performance analysis are carried out which estimates the performance parameters and reliability in operation of PV system. This paper proposes a neural network approach to performance prediction of PV Modules. Here the feed forward neural networks are used to predict I-V curve parameters as a function on input irradiance and temperature. K Fold cross-validation is used to validate model accuracy for determination of I-V curve parameters for five different technology modules, i.e., CdTe, CIGS, MICROMORPH, MUTICRYSTALLINE, MAXEON. A comparison is also drawn between the neural network predictor and the existing modeling procedures available. Model parameters have been determined following iterative, analytical and regression of known data points for seven and five parameter model of PV Modules. Among the electrical equivalent models, the seven parameter model is the most efficient model for performance prediction however commutation of model parameters in complex and tedious. Neural network model simplifies the computational process at the expense of higher error variance in comparison to electrical equivalent models. Further, a cascade implementation of the above two is designed and tested on Multicrystalline and Maxeon technology modules for higher model accuracy. The results obtained, verify the proposed cascaded model to be the most efficient model in comparison to independent models where mean bias error deviations are less than ±1% and error variance is reduced significantly. Also, a MATLAB based graphical user interface (GUI) is developed that can be used to predict the performance based on the analysis carried out. The proposed model is tested against a set of operating conditions and compared to the actual experimental values obtained using outdoor tests. [ABSTRACT FROM AUTHOR]

This paper reviews the evolution of Internal Model Control (IMC) techniques developed so far for unstable processes. The IMC strategy has shown significant results over the past two decades, including recent inclusions of fractional-order approaches. After a comprehensive study of various methods, the critical tuning methods and structural changes are clearly accumulated with their significance and limitation concerning controlling unstable time-delay systems. The comparisons with main structural changes and filter designs are also included in the numerical study and in discussion. Finally, the key research gaps and future motivations are indicated in the IMC approaches, considering available methods in the literature. • Internal Model Control (IMC) was found with significant performance for unstable time-delay processes. • A comprehensive study with emphasis on IMC evolution, filters and structures are summarized. • The advantages of incorporating fractional calculus in IMC is showcased. • The merit–demerit of various IMC schemes are tabulated for fare understanding. • The research gaps, existing challenges and future directions are accumulated for the IMC theory. [ABSTRACT FROM AUTHOR]

In this paper, a new approach is proposed to approximate the high-order linear time invariant (LTI) system into its low-order model. The proposed approach is a mixed method of model order reduction scheme consisting of recently developed big bang big crunch optimization algorithm and the time-moment matching method. This proposed method is applicable to single-input single-output, multi-input multi-output system, and time delayed LTI systems. The proposed approach is substantiated with various numerical examples of low and high-order systems. The results show that the reduced-order models preserve both transient and steady state conditions of original systems. Further, the results are also compared with the existing approaches of reduced order modeling which show exceptional improvement in integral square error ( ISE ) and other time domain specifications. [ABSTRACT FROM AUTHOR]

Till date, various load frequency control (LFC) schemes have been reported and every scheme has its own way of disturbance rejection capability. Utilizing some of them together may bring improved performance. Keeping this fact in mind, an adaptive control policy is proposed in this letter. The policy incorporates the concept of enhancing and lowering the controller activity by assigning them weights at every instance throughout the operation. Thus, there is no need to go for a new LFC scheme until required, and a guaranteed improved performance would be achieved. Different case studies including single and multi-area power systems have been conducted to verify the accuracy and efficiency of the proposed method. [ABSTRACT FROM PUBLISHER]