M. Willjuice Iruthayarajan

Evolutionary algorithms based design of multivariable PID controller

In this paper, performance comparison of evolutionary algorithms (EAs) such as real coded genetic algorithm (RGA), modified particle swarm optimization (MPSO), covariance matrix adaptation evolution strategy (CMAES) and differential evolution (DE) on optimal design of multivariable PID controller design is considered. Decoupled multivariable PI and PID controller structure for Binary distillation column plant described by Wood and Berry, having 2 inputs and 2 outputs is taken. EAs simulations are carried with minimization of IAE as objective using two types of stopping criteria, namely, maximum number of functional evaluations (Fevalmax) and Fevalmax along with tolerance of PID parameters and IAE. To compare the performances of various EAs, statistical measures like best, mean, standard deviation of results and average computation time, over 20 independent trials are considered. Results obtained by various EAs are compared with previously reported results using BLT and GA with multi-crossover approach. Results clearly indicate the better performance of CMAES and MPSO designed PI/PID controller on multivariable system. Simulations also reveal that all the four algorithms considered are suitable for off-line tuning of PID controller. However, only CMAES and MPSO algorithms are suitable for on-line tuning of PID due to their better consistency and minimum computation time.

Multi-objective robust PID controller tuning using two lbests multi-objective particle swarm optimization

In this paper, two lbests multi-objective particle swarm optimization (2LB-MOPSO) is applied to design multi-objective robust Proportional-integral-derivative (PID) controllers for two MIMO systems, namely, distillation column plant and longitudinal control system of the super maneuverable F18/HARV fighter aircraft. Multi-objective robust PID controller design problem is formulated by minimizing integral squared error (ISE) and balanced robust performance criteria. During the search, 2LB-MOPSO can focus on small regions in the parameter space in the vicinity of the best existing fronts. As the lbests are chosen from the top fronts in a non-domination sorted external archive of reasonably large size, the offspring obtained can be more diverse with good fitness. The performance of various optimal PID controllers is compared in terms of the sum of ISE and balanced robust performance criteria. For the purpose of comparison, 2LB-MOPSO, NSGA-II as well as earlier reported Riccati, IGA and OSA methods are considered. The performance of PID controllers obtained using 2LB-MOPSO is better than that of others. In addition, Hypervolume-based comparisons are carried out to show the superior performance of 2LB-MOPSO over NSGA-II. The results reveal that 2LB-MOPSO yields better robustness and consistency in terms of the sum of ISE and balanced robust performance criteria than various optimal PID controllers.

Covariance matrix adaptation evolution strategy based design of centralized PID controller

In this paper, design of centralized PID controller using Covariance Matrix Adaptation Evolution Strategy (CMAES) is presented. Binary distillation column plant described by Wood and Berry (WB) having two inputs and two outputs and by Ogunnike and Ray (OR) having three inputs and three outputs are considered for the design of multivariable PID controller. Optimal centralized PID controller is designed by minimizing IAE for servo response with unit step change. Simulations are carried out using SIMULINK-MATLAB software. The statistical performances of the designed controllers such as best, mean, standard deviations of IAE and average functional evaluations for 20 independent trials. For the purpose of comparison, recent version of real coded Genetic Algorithm (RGA) with simulated binary crossover (SBX) and conventional BLT method are used. In order to validate the performance of optimal PID controller for robustness against load disturbance rejection, load regulation experiment with step load disturbance is conducted. Also, to determine the performance of optimal PID controller for robustness against model uncertainty, servo and load response with +20% variations in gains and dead times is conducted. Simulation results reveal that for both OR and WB systems, CMAES designed centralized PID controller is better than other methods and also it is more robust against model uncertainty and load disturbance.

Covariance matrix adapted evolution strategy algorithm-based solution to dynamic economic dispatch problems

This article presents a covariance matrix adapted evolution strategy (CMAES) algorithm to solve dynamic economic dispatch (DED) problems. The DED is an extension of the conventional economic dispatch problem, in which optimal settings of generator units are determined with a predicted load demand over a period of time. In this article, the applicability and validity of the CMAES algorithm is demonstrated on three DED test systems with a sequential decomposition approach. The results obtained using the CMAES algorithm are compared with results obtained using the real-coded genetic algorithm, the Nelder–Mead simplex method, and other methods from the literature. To compare the performance of the various algorithms, statistical measures like best, mean, worst, standard deviation, and mean computation time over 20 independent runs are taken. The effect of population size on the performance of the CMAES algorithm is also investigated. The simulation experiments reveal that the CMAES algorithm performs better in terms of fuel cost and solution consistency. Karush–Kuhn–Tucker conditions are applied to the solutions obtained using the CMAES algorithm to verify optimality. It is found that the obtained results satisfy the Karush–Kuhn–Tucker conditions and confirm optimality.

Effect of antioxidants on critical properties of natural esters for liquid insulations

This work is focused towards identifying alternate insulating medium for replacing the mineral oil. With this aim, investigations are carried out with natural esters based vegetable oils which are considered as environmental friendly and biodegradable products. This work also extends to analyze the properties of vegetable oils with the antioxidants for enhanced insulating medium of transformer applications. The natural esters based vegetable oils such as honge oil, neem oil, mustard oil, punna oil and castor oil are considered as samples for the investigations. The butylated hydroxy toluene, butyalted hydroxy anisole and gallic acid are picked as the investigating antioxidants. Different particle volume fraction ranges from 0% to 1% of antioxidants are included for studying the performance of natural esters. The performances of natural esters without and with antioxidants are examined according to the international standards. From the investigation results, it is found that the natural esters based vegetable oils without and with antioxidants have the potential to replace the mineral oil as the insulating medium in the transformers. The mathematical functions for properties are developed based on the results obtained for various concentration of antioxidant. These functions are used to estimate the intermediate values of properties for different antioxidant concentrations.

Analysis of vegetable liquid insulating medium for applications in high voltage transformers

In high voltage transformers, the liquid insulations are used as the insulating medium as well as cooling medium. For the past several decades, the mineral based transformer oil is used traditionally for the purpose of liquid insulations. In the environmental aspect, there are several disadvantages in the mineral oil even though it has better insulating properties. By considering the environmental aspect and insulating properties, the researchers tend to find the alternate insulating fluids for the high voltage applications. In this work, the natural ester based vegetable oils are investigated to analyze the suitability of it as better insulating medium. The different vegetable oils such as mustard oil, olive oil, gingelly oil, groundnut oil, sunflower oil, palm olein oil and rice bran oil are investigated with the measurement of properties like breakdown voltage, flash point, fire point and viscosity. Further analysis are made with the comparison of properties, the fatty acid content and cost of vegetable oils. From the investigations, it is shown that the natural ester based vegetable oils have the potential to replace the traditional mineral oil.

Multiobjective Mobile Antenna Location identification using evolutionary optimization algorithm

In this paper, Multiobjective Mobile Antenna Location identification problem is considered with site coordinates (x, y), transmitting power, height, and tilt angle as design parameters and maximization of service coverage and minimization of cost as objectives. Evolutionary multiobjective algorithm NSGA-II and modified NSGA-II by incorporating dynamic crowding distance and controlled elitism is considered. A 15×15 Km2 synthetic test system is taken for simulation purposes. From the simulation results, we realize that modified NSGA-II is able to generate better Paretofront in terms of diversity and uniformity.

Multi-objective robust PID controller tuning using multi-objective differential evolution

PID controller has been widely applied in engineering area. In this paper, multi-objective differential evolution (MODE) is used to design a multi-objective robust PID controller for two MEMO systems known as distillation column plant and longitudinal control system of the super maneuverable F18/HARV fighter aircraft. Multi-objective robust PID controller problem is formulated by minimizing integral squared error (ISE) and balanced robust performance criteria. The performance of the optimum PID controllers that obtain by MODE is compared with performance reported in literature by other methods in terms of the sum of ISE and balanced robust performance criteria. The results show that the PID controllers obtained by MODE can outperform various optimal PID controllers reported in literature.

Performance of natural high oleic ester based blended oil insulation for transformer

Energy requirements of whole world have been dominated by petroleum products for many years in various application fields. In order to find the potential replacement for conventional mineral oil, natural based ester oil is proposed as alternative liquid insulation with the consideration of eco-friendly nature among ester oil, the oil with oleic acid content has oxidation resistance and low viscous nature. In this work blending of mineral and high oleic ester oil with different ratio were carried out to study the typical characteristics of blended liquid as liquid insulation. Olive oil and rapeseed oil which has high oleic acid content are selected for investigation. Investigation properties like viscosity, breakdown voltage, flash point, acidity, moisture content and moisture saturation rate were measured for different combinations as per international standards (IEC and ASTM). Investigation reveals that both olive and rapeseed based blended oil show better characteristics, among that olive based blended oil have superior properties than that of rapeseed oil.

Investigation of vegetable oil blended with antioxidant

The Energy requirements of the total world have been subjugated by petroleum products for centuries in many application fields including transportation, household, and electricity. Traditionally, mineral oil is used as insulating fluids in transformer. Mineral oil in transformer can be potentially hazardous to the environment when there is any accident during its working time. In order to conquer these facts, vegetable oil is projected as substitute for transformer oil because it is more environments friendly. In this work, investigation of various parameters like breakdown voltage, viscosity, water content, interfacial tension, acidity, flash point and fire point of different vegetable oils like sunflower oil, rice bran oil, soybean oil and corn oil are carried out. This work is extended to analyze blending of various proportions of antioxidant to different vegetable oils. The different parameters like breakdown voltage, viscosity, water content, interfacial tension, acidity, flash point and fire point are measured. From the investigations, the more suitable combination for transformer insulation is figured out, which has properties similar or superior to mineral oil.