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The paper has proposed to implement gray wolf optimization (GWO)-based filter-type proportional derivative with (FPD) plus (1+ proportional integral) multistage controller in a three-area integrated source-type interlinked power network for achieving automatic generation control.

For analysis, a three area interconnected power system of which each area comprises three different generating units where thermal and hydro system as common. Micro sources like wind generator, diesel generator and gas unit are integrated with area1, area2 and area3 respectively. For realization of system nonlinearity some physical constraints like generation rate constraint, governor dead band and boiler dynamics are effected in the system.

The supremacy of multistage controller structure over simple proportional integral (PI), proportional integral, derivative (PID) and GWO technique over genetic algorithm, differential evolution techniques has been demonstrated. A comparison is made on performances of different controllers and sensitivity analysis on settling times, overshoots and undershoots of different dynamic responses of system as well as integral based error criteria subsequent a step load perturbation (SLP). Finally, sensitive analysis has been analyzed by varying size of SLP and network parameters in range ±50 per cent from its nominal value.

Design and implementation of a robust FPD plus (1 + PI) controller for AGC of nonlinear power system. The gains of the proposed controller are optimized by the application of GWO algorithm. An investigation has been done on the dynamic performances of the suggested system by conducting a comparative analysis with conventional PID controller tuned by various optimization techniques to verify its supremacy. Establishment of the robustness and sensitiveness of the controller by varying the size and position of the SLP, varying the loading of the system randomly and varying the time constants of the system.

This study focuses on the application of reliability-centered maintenance (RCM) to a textile industry steam boiler. The study aims to demonstrate the development and application of RCM to a steam boiler used in the textile industry.

RCM is a structured process that develops maintenance activities needed on physical resources in their operational environment to realize their inherent reliability by logically incorporating an appropriate mixture of reactive, preventive, condition-based and proactive maintenance methods. A detailed analysis of the RCM approach is presented to develop preventive maintenance (PM) program and improve the reliability and availability of the steam boiler system.

The research reveals that the identification of PM tasks is a good indicator of the PM program's efficiency and can serve as an important maintenance-related downtime source. It is also discovered that the majority of maintenance programs that claim to be proactive are, in fact, reactive. This article also shows how RCM may be successfully implemented to any system, resulting in increased system reliability.

The paper focuses on a pilot study of the development and implementation of the RCM technique to a textile industry steam boiler. It is suggested that the developed RCM model can be applied to the entire plant.

The paper presents a comprehensive RCM model framework as well as an RCM decision framework, providing maintenance managers and engineers with a step-by-step approach to RCM implementation. The proposed framework is significant in that it may be utilized for both qualitative and quantitative analysis at the same time.

This study aims to perform a numerical study of air convection in a rectangular enclosure with two isothermal blocks and oscillating bottom wall temperature under laminar flow conditions. The geometry of the enclosure contains two isothermal blocks placed equidistant along the streamwise direction. The top wall is assumed to be cold (low temperature). The bottom wall temperature is either kept as constant or sinusoidally varied with time. The vertical walls are considered as adiabatic. The flow is diagonally upwards and assisted by the buoyancy force. The inlet is positioned at the bottom of the left wall, and the outlet is placed at the top of the right wall. The parameters considered in this paper are Rayleigh number (104-106), Prantdl number (0.71), amplitude of temperature oscillation (0-0.5) and the period (0.2). The effects of these parameters on heat transfer and fluid flow inside the open cavity are studied. The periodic results of fluid flow are illustrated with streamlines and the heat transfer is represented by isotherms and time-averaged Nusselt number. By virtue of increasing buoyancy, the heat transfer accelerates with an increase in the Rayleigh number. Also, the heat transfer is intensive with an increase in the bottom wall temperature.

The momentum and energy equations are solved simultaneously. The energy equation (3) is initially solved using the alternating direction implicit (ADI) method. The results of the energy equation are updated into the vorticity equation. The unsteady vorticity transport equation is also solved using the ADI method. Dimensionless time step equal to 0.01 is used for high Ra (10⁵ and 10⁶) and 0.001 is used for low Ra (10⁴). Convergence criteria of 10⁻⁵ is used during the vorticity, stream function and temperature calculations, as the sum of error should be very small.

Numerical study of air convection in a rectangular enclosure with two isothermal blocks and oscillating bottom wall temperature is performed under laminar flow condition. The effect of the isothermal blocks on the heat transfer is analyzed for different Rayleigh numbers and the following conclusions are arrived. The hydrodynamic blockage effect is subdued by the isothermal heating of square blocks. Based on the streamline diagrams, it is found that the formation of vortices is greatly influenced by the Rayleigh number when all the walls are exposed to a constant wall temperature. The influence of amplitude on the heat transfer is remarkable on the wall exposed to oscillating temperature and is subtle on the opposite static cold wall. The heat transfer increases with an increase in the Rayleigh number and temperature.

Flow is assumed to be two-dimensional and laminar subject to oscillatory boundary condition. The present investigation aims to study natural convection inside the cavity filled with air whose bottom wall is subject to time-variant temperature. The buoyancy is further intensified through two isothermal square blocks placed equidistant along the streamwise direction at mid-height.

The authors have developed a CFD solver to simulate the situation. Effect of Rayleigh number subject to oscillatory thermal boundary condition is simulated. Streamline contour and isotherm contour are presented. Local and average Nusselt numbers are presented.

The purpose of this paper is to develop, extend and propose an improved proportional integral derivative (PID) rate control of a quadrotor unmanned aerial vehicle based on a convexity-based surrogated firefly algorithm.

An improved PID controller structure is proposed for the rate dynamics of the quadrotor. Optimality of the controller is ensured by a recent, simple yet efficient firefly optimization method. The hybrid structure is further enhanced with a convexity-based surrogated model function.

Monte Carlo, transient response, error metrics and histogram distribution analyzes are conducted to show the performance of the proposed controller. The performance of the proposed method is evaluated under various convex combination values to further investigate the effect of the proposed surrogated model. According to the results, the proposed method is capable of controlling the rate quadrotor dynamics with the steady-state error of 0.0023 (rad/s) for P, −0.0024 (rad/s) for Q and 0 (rad/s) for the R state, respectively. Also, the least mean objective value is achieved at = 0 value of convexity in Monte Carlo trials.

The originality of this paper is to propose an improved PID rate controller with a convexity-based surrogated firefly algorithm.

The purpose of this paper is to study the effect of a computational grid in computational fluid dynamics‐based mathematical modeling, focusing on but not limiting the attention to industrial‐scale boilers.

A full boiler model is used to show the difficulties related to judging iteration and discretization errors in boiler modeling. Then, a single jet is studied in detail to determine the proper degree of local grid refinement required in the vicinity of jets in the full boiler model. Both a nonreactive axisymmetric jet exhausting into a quiescent atmosphere and a reactive jet exhausting into a crossfiow are studied.

Over two million computational cells are required for the grid‐independent solution for a single jet. Local grid refinement is shown to be a good option for improving the results consistently without an excessive increase in the number of computational cells. Using relatively coarse grids of tetrahedral cells with a finite‐volume‐based solver may cause serious errors in results, typically by overpredicting the jet spreading rate and underpredicting the mean axial centerline velocity. Relatively coarse grids of hexahedral cells are less prone to error in a case where a jet exhausts into a quiescent atmosphere. However, their performance deteriorates when a crossfiow is introduced. As assumed, the differences in the predicted reaction rate and species concentrations are significant in the reactive case. It is confirmed that the standard k‐ε model tends to overpredict the axisymmetric jet spreading rate. The estimated inlet turbulence intensity is not among the most critical factors in modeling. Estimations of the axisymmetric jet centerline velocity from the analytical correlation may not coincide with the modeling results.

The error caused by the computational grid may easily dominate the errors caused by simplifying models used in industrial‐scale boiler modeling (turbulence, combustion, radiative heat transfer, etc.).

The present study deals with grid independency issues in industrial‐scale boiler modeling in a systematic and profound manner.

In this paper, a novel Lyapunov–Krasovskii stable fuzzy proportional-integral-derivative (PID) (FPID) controller is introduced for load frequency control of a time-delayed micro-grid (MG) system that benefits from a fuel cell unit, wind turbine generator and plug-in electric vehicles.

Using the Lyapunov–Krasovskii theorem, the adaptation laws for the consequent parameters and output scaling factors of the FPID controller are developed in such a way that an upper limit (the maximum permissible value) for time delay is introduced for the stability of the closed-loop MG system. In this way, there is a stable FPID controller, the adaptive parameters of which are bounded. In the obtained adaptation laws and the way of stability analyses, there is no need to approximate the nonlinear model of the controlled system, which makes the implementation process of the proposed adaptive FPID controller much simpler.

It has been shown that for a different amount of time delay and intermittent resources/loads, the proposed adaptive FPID controller is able to enforce the frequency deviations to zero with better performance and a less amount of energy. In the proposed FPID controller, the increase in the amount of time delay leads to a small increase in the amount of overshoot/undershoot and settling time values, which indicate that the proposed controller is robust to the time delay changes.

Although the designed FPID controllers in the literature are very efficient in being applied to the uncertain and nonlinear systems, they suffer from stability problems. In this paper, the stability of the FPID controller has been examined in applying to the frequency control of a nonlinear input-delayed MG system. Based on the Lyapunov–Krasovskii theorem and using rigorous mathematical analyses, the stability conditions and the adaptation laws for the parameters of the FPID controller have been obtained in the presence of input delay and nonlinearities of the MG system.

The design and retrofit of the heat exchangers in a boiler should take into account the processes occurring on the side of combustion and steam. For this reason, this study aims to couple a one-dimensional hydrodynamic model of steam with computational fluid dynamics (CFD) simulation of flue gas.

Radiant/semi-radiant platen heat exchangers are simplified as plane surfaces for CFD, while convective heat exchangers are introduced into the CFD simulation as energy/momentum absorption sources.

Numerical simulation is performed for a 1,000 MWe coal-fired ultra-supercritical boiler. The calculation results are validated by the thermodynamic design data. Tube outside surface temperature, as well as ash deposit temperature distributions, are obtained.

Complex tube arrangements can be completed with the aid of AutoCAD, and therefore, the simulation could offer detailed information of heat exchangers. In a word, a more reliable modeling of the whole steam generation process is achieved.

A fully three‐dimensional model has been applied to an oil‐fired water tube boiler in order to predict the flow, temperature, mixture fraction, species concentrations and the heat flux distributions to the furnace walls. The partial differential equations governing conservation of mass, momentum and energy as well as those describing the combustion phenomena are discretized by a finite volume method and solved numerically. Radiative heat transfer is handled by the discrete transfer method. Predicted results are presented and compared with experimental data for the heat fluxes. The results have suggested that 3‐D models of the present kind can be used with some confidence for design calculations.

Combustion modifications to minimize NO_X emissions have magnified the importance of waterwall corrosion in coal‐fired boilers. The physics and chemistry controlling corrosion processes can be highly non‐linear and are challenging to describe in terms of their likely overall combustion behavior. This paper describes the application of a multi‐point, real time corrosion surveillance system to a large boiler firing high sulfur coal. This technology, incorporating electrochemical sensing and wireless signal transmission, enables combustion engineers and plant operating personnel to make informed decisions regarding the quantitative relationships between operating conditions, NO_X emissions, and any resultant extent/magnitude of waterwall corrosion.

This paper sets out to study the corrosion of No. 20 carbon steel without film and with films of different qualities in high‐temperature boiler water with different Cl⁻ concentrations.

The static simulated experiment in high‐pressure autoclave and the surface analysis methods of EPMA and XRD were carried out to study the corrosion effect.

Under the following conditions: T=360±3°C, pH = 9.40±0.10, c_O2<0.020 mg/l, the density of pitting corrosion on specimens without a protective film increased with the increase of C_Cl⁻ content, while C_Cl⁻ was > 0.2 mg/l. The film on specimens with integral films would not dissolve observably even until the C_Cl⁻ concentration was as high as 0.8 mg/l. Films with corrosion pits would begin dissolving when the Cl⁻ concentration reached 0.4 mg/l. The main constituents of the oxidative films in the gas and liquid phases both were Fe₃O₄.

In order to prevent carbon steel from corroding in boiler water containing Cl⁻ under conditions of low‐phosphate and low‐sodium hydroxide treatment, the concentration of Cl⁻ should be strictly controlled.

It was found that the presence of excessive Cl⁻ in boiler water accelerated the corrosion of No. 20 carbon steel and the maximum permissible concentration of Cl⁻ under the conditions (temperature and pressure) of sub‐critical drum boilers was 0.2 mg/l. The research results can provide theoretical guidelines for preventing the facilities of power plants from corroding.