Artificial Bee Colony Algorithm Combined with Grenade Explosion Method and Cauchy Operator for Global Optimization

Artificial bee colony (ABC) algorithm is a popular swarm intelligence technique inspired by the intelligent foraging behavior of honey bees. However, ABC is good at exploration but poor at exploitation and its convergence speed is also an issue in some cases. To improve the performance of ABC, a novel ABC combined with grenade explosion method (GEM) and Cauchy operator, namely, ABCGC, is proposed. GEM is embedded in the onlooker bees' phase to enhance the exploitation ability and accelerate convergence of ABCGC; meanwhile, Cauchy operator is introduced into the scout bees' phase to help ABCGC escape from local optimum and further enhance its exploration ability. Two sets of well-known benchmark functions are used to validate the better performance of ABCGC. The experiments confirm that ABCGC is significantly superior to ABC and other competitors; particularly it converges to the global optimum faster in most cases. These results suggest that ABCGC usually achieves a good balance between exploitation and exploration and can effectively serve as an alternative for global optimization

МЕТАЭВРИСТИЧЕСКИЕ МЕТОДЫ ОПТИМИЗАЦИИ В ЗАДАЧАХ ОЦЕНКИ ПАРАМЕТРОВ ДИНАМИЧЕСКИХ СИСТЕМ

The article considers the usage of metaheuristic methods of constrained global optimization: “Big Bang - Big Crunch”, “Fireworks Algorithm”, “Grenade Explosion Method” in parameters of dynamic systems estimation, described with algebraic-differential equations. Parameters estimation is based upon the observation results from mathematical model behavior. Their values are derived after criterion minimization, which describes the total squared error of state vector coordinates from the deduced ones with precise values observation at different periods of time. Paral- lelepiped type restriction is imposed on the parameters values. Used for solving problems, metaheuristic methods of constrained global extremum don’t guarantee the result, but allow to get a solution of a rather good quality in accepta- ble amount of time. The algorithm of using metaheuristic methods is given. Alongside with the obvious methods for solving algebraic-differential equation systems, it is convenient to use implicit methods for solving ordinary differen- tial equation systems. Two ways of solving the problem of parameters evaluation are given, those parameters differ in their mathematical model. In the first example, a linear mathematical model describes the chemical action parameters change, and in the second one, a nonlinear mathematical model describes predator-prey dynamics, which characterize the changes in both kinds’ population. For each of the observed examples there are calculation results from all the three methods of optimization, there are also some recommendations for how to choose methods parameters. The obtained numerical results have demonstrated the efficiency of the proposed approach. The deduced parameters ap- proximate points slightly differ from the best known solutions, which were deduced differently. To refine the results one should apply hybrid schemes that combine classical methods of optimization of zero, first and second orders and heuristic procedures.Рассмотрено применение метаэвристических методов условной глобальной оптимизации: «большого взрыва - большого сжатия», «фейерверков», «взрыва гранат» в задачах оценки параметров динамических моделей, описываемых дифференциально-алгебраическими уравнениями. Оценка параметров производится по результатам наблюдений за поведением математической модели. Их значения находятся в результате минимизации критерия, описывающего суммарное квадратическое отклонение значений координат вектора состояния от полученных при измерениях точных значений в различные моменты времени. На значения параметров наложены ограничения параллелепипедного типа. Применяемые для решения задачи оптимизации метаэвристические методы поиска условного глобального экстремума не гарантируют нахождения результата, но позволяют получать решение достаточно хорошего качества за приемлемое время. Описана стратегия применения метаэвристических методов. Для решения систем дифференциально-алгебраических уравнений наряду с явными методами удобно применять неявные методы решения систем обыкновенных дифференциальных уравнений. Приведены два примера решения задачи оценивания параметров, отличающиеся видом математической модели. В первой задаче линейная математическая модель описывает изменение параметров химического процесса, а во второй нелинейная модель описывает процесс хищник-жертва, характеризующий изменение популяции из двух видов. Для каждой из рассмотренных моделей приведены результаты расчетов всеми тремя методами оптимизации, даны рекомендации по выбору параметров методов. Полученные численные результаты продемонстрировали эффективность предложенного подхода. Найденные приближенные значения оцениваемых параметров незначительно отличаются от лучших известных решений, полученных другими способами. Для уточнения полученных результатов рекомендуется применять гибридные алгоритмы, сочетающие классические методы оптимизации нулевого, первого и второго порядков и эвристические процедуры

Permütasyon Akış Tipi Çizelgeleme Probleminin El Bombası Patlatma Metodu ile Çözümü

Üretimde kaynakların verimli kullanımı için işlerin en iyi şekilde çizelgelenmesi gerekmektedir. Gerçek hayatta çok sayıda uygulaması bulunan permütasyon akış tipi çizelgeleme problemi (PATÇP) yarım asırdan uzun süredir araştırmacıların ilgisini çekmektedir. El Bombası Patlatma Metodu (EBPM) Ahrari ve arkadaşları tarafından el bombalarının patlamalarından esinlenerek geliştirilmiş evrimsel bir algoritmadır. Bu çalışmada EBPM, permütasyon akış tipi çizelgeleme problemlerinin çözümü için uyarlanmıştır. Daha sonra metodu diğer metasezgisellerden ayıran özellik olan ajan bölgesi yarıçapının metot performansına etkisi araştırılmış ve metodun maksimum tamamlanma zamanı performans ölçütüne göre Taillard tarafından geliştirilmiş olan test problemleri üzerindeki performansları incelenmiştir. Sonuç olarak EBPM’nin makul sürelerde kabul edilebilir sonuçlara ulaşabildiği ve PATÇP’lerin çözümünde kullanılabileceği görülmüştür

Performance Analysis of Photovoltaic Fed Distributed Static Compensator for Power Quality Improvement

Owing to rising demand for electricity, shortage of fossil fuels, reliability issues, high transmission and distribution losses, presently many countries are looking forward to integrate the renewable energy sources into existing electricity grid. This kind of distributed generation provides power at a location close to the residential or commercial consumers with low transmission and distribution costs. Among other micro sources, solar photovoltaic (PV) systems are penetrating rapidly due to its ability to provide necessary dc voltage and decreasing capital cost. On the other hand, the distribution systems are confronting serious power quality issues because of various nonlinear loads and impromptu expansion. The power quality issues incorporate harmonic currents, high reactive power burden, and load unbalance and so on. The custom power device widely used to improve these power quality issues is the distributed static compensator (DSTATCOM). For continuous and effective compensation of power quality issues in a grid connected solar photovoltaic distribution system, the solar inverters are designed to operate as a DSTATCOM thus by increasing the efficiency and reducing the cost of the system. The solar inverters are interfaced with grid through an L-type or LCL-type ac passive filters. Due to the voltage drop across these passive filters a high amount of voltage is maintained across the dc-link of the solar inverter so that the power can flow from PV source to grid and an effective compensation can be achieved. So in the thesis a new topology has been proposed for PV-DSTATCOM to reduce the dc-link voltage which inherently reduces the cost and rating of the solar inverter. The new LCLC-type PV-DSTATCOM is implemented both in simulation and hardware for extensive study. From the obtained results, the LCLC-type PV-DSTATCOM found to be more effective than L-type and LCL-type PV-DSTATCOM. Selection of proper reference compensation current extraction scheme plays the most crucial role in DSTATCOM performance. This thesis describes three time-domain schemes viz. Instantaneous active and reactive power (p-q), modified p-q, and IcosΦ schemes. The objective is to bring down the source current THD below 5%, to satisfy the IEEE-519 Standard recommendations on harmonic limits. Comparative evaluation shows that, IcosΦ scheme is the best PV-DSTATCOM control scheme irrespective of supply and load conditions. In the view of the fact that the filtering parameters of the PV-DSTATCOM and gains of the PI controller are designed using a linearized mathematical model of the system. Such a design may not yield satisfactory results under changing operating conditions due to the complex, nonlinear and time-varying nature of power system networks. To overcome this, evolutionary algorithms have been adopted and an algorithm-specific control parameter independent optimization tool (JAYA) is proposed. The JAYA optimization algorithm overcomes the drawbacks of both grenade explosion method (GEM) and teaching learning based optimization (TLBO), and accelerate the convergence of optimization problem. Extensive simulation studies and real-time investigations are performed for comparative assessment of proposed implementation of GEM, TLBO and JAYA optimization on PV-DSTATCOM. This validates that, the PV-DSTATCOM employing JAYA offers superior harmonic compensation compared to other alternatives, by lowering down the source current THD to drastically small values. Another indispensable aspect of PV-DSTATCOM is that due to parameter variation and nonlinearity present in the system, the reference current generated by the reference compensation current extraction scheme get altered for a changing operating conditions. So a sliding mode controller (SMC) based p-q theory is proposed in the dissertation to reduce these effects. To validate the efficacy of the implemented sliding mode controller for the power quality improvement, the performance of the proposed system with both linear and non-linear controller are observed and compared by taking total harmonic distortion as performance index. From the obtained simulation and experimentation results it is concluded that the SMC based LCLC-type PV-DSTATCOM performs better in all critical operating conditions

A Novel Algorithm for Solving Structural Optimization Problems

In the past few decades, metaheuristic optimization methods have emerged as an effective approach for addressing structural design problems. Structural optimization methods are based on mathematical algorithms that are population-based techniques. Optimization methods use technology development to employ algorithms to search through complex solution space to find the minimum. In this paper, a simple algorithm inspired by hurricane chaos is proposed for solving structural optimization problems. In general, optimization algorithms use equations that employ the global best solution that might cause the algorithm to get trapped in a local minimum. Hence, this methodology is avoided in this work. The algorithm was tested on several common truss examples from the literature and proved efficient in finding lower weights for the test problems

An elitist teaching-learning-based optimization algorithm for solving complex constrained optimization problems

Nature inspired population based algorithms is a research field which simulates different natural phenomena to solve a wide range of problems. Researchers have proposed several algorithms considering different natural phenomena. Teaching-Learning-based optimization (TLBO) is one of the recently proposed population based algorithm which simulates the teaching-learning process of the class room. This algorithm does not require any algorithm-specific control parameters. In this paper, elitism concept is introduced in the TLBO algorithm and its effect on the performance of the algorithm is investigated. The effects of common controlling parameters such as the population size and the number of generations on the performance of the algorithm are also investigated. The proposed algorithm is tested on 35 constrained benchmark functions with different characteristics and the performance of the algorithm is compared with that of other well known optimization algorithms. The proposed algorithm can be applied to various optimization problems of the industrial environment