Load Frequency Control (LFC) Strategies in Renewable Energy‐Based Hybrid Power Systems:A Review

The hybrid power system is a combination of renewable energy power plants and conventional energy power plants. This integration causes power quality issues including poor settling times and higher transient contents. The main issue of such interconnection is the frequency variations caused in the hybrid power system. Load Frequency Controller (LFC) design ensures the reliable and efficient operation of the power system. The main function of LFC is to maintain the system frequency within safe limits, hence keeping power at a specific range. An LFC should be supported with modern and intelligent control structures for providing the adequate power to the system. This paper presents a comprehensive review of several LFC structures in a diverse configuration of a power system. First of all, an overview of a renewable energy-based power system is provided with a need for the development of LFC. The basic operation was studied in single-area, multi-area and multi-stage power system configurations. Types of controllers developed on different techniques studied with an overview of different control techniques were utilized. The comparative analysis of various controllers and strategies was performed graphically. The future scope of work provided lists the potential areas for conducting further research. Finally, the paper concludes by emphasizing the need for better LFC design in complex power system environments

Energy management in microgrids with renewable energy sources: A literature review

Renewable energy sources have emerged as an alternative to meet the growing demand for energy, mitigate climate change, and contribute to sustainable development. The integration of these systems is carried out in a distributed manner via microgrid systems; this provides a set of technological solutions that allows information exchange between the consumers and the distributed generation centers, which implies that they need to be managed optimally. Energy management in microgrids is defined as an information and control system that provides the necessary functionality, which ensures that both the generation and distribution systems supply energy at minimal operational costs. This paper presents a literature review of energy management in microgrid systems using renewable energies, along with a comparative analysis of the different optimization objectives, constraints, solution approaches, and simulation tools applied to both the interconnected and isolated microgrids. To manage the intermittent nature of renewable energy, energy storage technology is considered to be an attractive option due to increased technological maturity, energy density, and capability of providing grid services such as frequency response. Finally, future directions on predictive modeling mainly for energy storage systems are also proposed

A Hankel Matrix Based Reduced Order Model for Stability Analysis of Hybrid Power System Using PSO-GSA Optimized Cascade PI-PD Controller for Automatic Load Frequency Control

This paper presents the automatic load frequency control (ALFC) of two-area multisource hybrid power system (HPS). The interconnected HPS model consists of conventional and renewable energy sources operating in disparate combinations to balance the generation and load demand of the system. In the proffered work, the stability analysis of nonlinear dynamic HPS model was analyzed using the Hankel method of model order reduction. Also, an attempt was made to apply cascade proportional integral - proportional derivative (PI-PD) control for HPS. The gains of the controller were optimized by minimizing the integral absolute error (IAE) of area control error using particle swarm optimization-gravitational search algorithm (PSO-GSA) optimization technique. The performance of cascade control was compared with other classical controllers and the efficiency of this approach was studied for various cases of HPS model. The result shows that the cascade control produced better transient and steady state performances than those of the other classical controllers. The robustness analysis also reveals that the system overshoots/undershoots in frequency response pertaining to random change in wind power generation and load perturbations were significantly reduced by the proposed cascade control. In addition, the sensitivity analysis of the system was performed, with the variation in step load perturbation (SLP) of 1% to 5%, system loading and inertia of the system by ±25% of nominal values to prove the efficiency of the controller. Furthermore, to prove the efficiency of PSO-GSA tuned cascade control, the results were compared with other artificial intelligence (AI) methods presented in the literature. Further, the stability of the system was analyzed in frequency domain for different operating cases

Symmetry in Renewable Energy and Power Systems

This book includes original research papers related to renewable energy and power systems in which theoretical or practical issues of symmetry are considered. The book includes contributions on voltage stability analysis in DC networks, optimal dispatch of islanded microgrid systems, reactive power compensation, direct power compensation, optimal location and sizing of photovoltaic sources in DC networks, layout of parabolic trough solar collectors, topologic analysis of high-voltage transmission grids, geometric algebra and power systems, filter design for harmonic current compensation. The contributions included in this book describe the state of the art in this field and shed light on the possibilities that the study of symmetry has in power grids and renewable energy systems

A modified whale optimization algorithm-based adaptive fuzzy logic PID controller for load frequency control of autonomous power generation systems

An autonomous power generation system (APGS) contains units such as diesel energy generator, solar photovoltaic units, wind turbine generator and fuel cells along with energy-storing units such as the flywheel energy storage system and battery energy storage system. The components either run at lower/higher power output or may turn on/off at different instants of their operation. Due to this, the conventional controllers will not provide desired performance under varied load conditions. This paper proposes an adaptive fuzzy logic PID (AFPID) controller for load frequency control. In order to achieve an improved performance, a modified whale optimization algorithm (mWOA) was also proposed in this paper for tuning of the AFPID parameters. The proposed algorithm was first evaluated using standard test functions and compared with other recent algorithms to authenticate the competence of algorithm. The proposed mWOA algorithm outperforms PSO, GSA, DE and FEP algorithms in five out of seven unimodal test functions and four out of six multimodal test functions. The effectiveness of the AFPID compared with the conventional PID and the proposed AFPID provides better performance. Reduction of 39.13% in error criteria (objective function) compared with WOA-PID controller. The proposed approach was also compared with some recently proposed frequency control approaches in a widely used two-area test system

Advanced and Innovative Optimization Techniques in Controllers: A Comprehensive Review

New commercial power electronic controllers come to the market almost every day to help improve electronic circuit and system performance and efficiency. In DC–DC switching-mode converters, a simple and elegant hysteretic controller is used to regulate the basic buck, boost and buck–boost converters under slightly different configurations. In AC–DC converters, the input current shaping for power factor correction posts a constraint. But, several brilliant commercial controllers are demonstrated for boost and fly back converters to achieve almost perfect power factor correction. In this paper a comprehensive review of the various advanced optimization techniques used in power electronic controllers is presented

Frequency deviations stabilizations in restructured power systems using coordinative controllers

Modern restructured power system faces excessive frequency aberrations due to the intermittent renewable generations and persistently changing load demands. An efficient and robust control strategy is obligatory to minimise deviations in the system frequency and tie-line to avoid any possible blackout. Hence, in this research, to achieve this target, automatic generation control (AGC) is utilized as a secondary controller to alleviate the changes in interconnected restructured systems at uncertainties. The objective of AGC is to quickly stabilize the deviations in frequency and tie-line power following load fluctuations. This thesis addresses the performance of AGC in two-area restructured power systems with many sophisticated control strategies in the presence of renewable and traditional power plants. As per literature of research work, there are quite a few research studies on AGC of a restructured system using optimized coordinative controllers. Besides, investigations on advanced optimized-based coordinative controller approaches are also rare to find in the literature. So, various combinations of two degrees of freedom (2DOF) controllers are utilized as supplementary controllers to diminish the frequency deviations. Nevertheless, the interconnected tie-lines are typically congested in areas with huge penetration of renewable sources, which may reduce the tie -line capability. Therefore, distinct FACTS controllers and ultra-capacitor (UC) are integrated into two-area restructured systems for strengthening the tie-line power and frequency. Further, new optimization techniques such as cuckoo search (CS), bat algorithm (BA), moth-flame optimization (MFO) are utilized in this work for investigating the suggested 2DOF controllers and compared their performance in all contracts of restructured systems. As per the simulation outcomes, the amalgamation of DPFC and UC with MFObased 2DOF PID-FOPDN shows low fluctuation rate in frequency and tie-line power. Besides, the settling times (ST) of two areas are 9.5 S for ΔF1, 8.2 S for ΔF2, and 10.15 S for ΔPtie. The robustness of the suggested controller has been verified by ±25% variations in system parameters and loading conditions

Efficiency and Sustainability of the Distributed Renewable Hybrid Power Systems Based on the Energy Internet, Blockchain Technology and Smart Contracts-Volume II

The climate changes that are becoming visible today are a challenge for the global research community. In this context, renewable energy sources, fuel cell systems, and other energy generating sources must be optimally combined and connected to the grid system using advanced energy transaction methods. As this reprint presents the latest solutions in the implementation of fuel cell and renewable energy in mobile and stationary applications, such as hybrid and microgrid power systems based on the Energy Internet, Blockchain technology, and smart contracts, we hope that they will be of interest to readers working in the related fields mentioned above

Optimización de sistemas híbridos aislados alimentados con fuentes renovables de energía

La mayoría de la energía eléctrica es transportada mediante las redes de distribución eléctricas desde el lugar de producción hasta el lugar de consumo. Sin embargo, hay lugares, debido a que el pequeño consumo no lo justifica o cuando la extensión de dichas redes es demasiado costosa (ya que son zonas remotas o existen limitaciones geográficas para los trazados), donde estas redes de distribución no llegan. En estos casos, la alternativa a la red eléctrica es generar “in situ” la propia energía eléctrica que ha de ser consumida. Este tipo de sistemas son los llamados sistemas aislados. La solución más habitual hasta hace unos años era satisfacer la demanda eléctrica en estos emplazamientos aislados mediante sistemas basados en grupos generadores de corriente alterna.Pero la inestabilidad del precio de los combustibles fósiles (normalmente en aumento), unido a la necesidad creciente de generar energía de forma limpia y sostenible, hizo que se orientaran estos sistemas hacia las energías renovables. La mejora de las distintas tecnologías relacionadas con estas fuentes de energía y el descenso de los costes de generación (principalmente de energía fotovoltaica y eólica) han hecho que desde hace algunos años haya sido una solución muy demandada para satisfacer el consumo energético en muchos lugares aislados.El principal problema de los sistemas basados exclusivamente en un tipo de energía renovable es la variabilidad de la climatología y por lo tanto su carácter intermitente. Ello hace que si se quiere asegurar el suministro, se deba sobredimensionar el sistema de generación, o el sistema de almacenamiento, o ambos; lo que incurre en un encarecimiento global de la instalación.Una solución al problema anterior son los sistemas híbridos de energías renovables. Estos sistemas de generación emplean dos o más fuentes diferentes de energía para transformarla en energía eléctrica. Gracias a ello, se consigue aumentar la fiabilidad del suministro eléctrico, al estar basado en más de una fuente de energía. Además, al ser sistemas más fiables, se puede disminuir la capacidad del necesario sistema de almacenamiento de energía (normalmente un banco de baterías de tipo plomo-ácido).Sin embargo, la tendencia actual, en sistemas de cierta envergadura, es la generación mediante sistemas híbridos entre energías renovables y generadores diésel. Frente a sistemas basados exclusivamente por generadores diésel o frente a sistemas basados en una única fuente de energía renovable, los sistemas híbridos renovables-diésel presentan numerosas ventajas.Como todo sistema de generación de energía eléctrica, estos sistemas deben cumplir con dos objetivos primordiales: garantizar el suministro de energía eléctrica y reducir al máximo el coste del mismo y de su operación. Ambos objetivos influyen decisivamente en el dimensionado óptimo de cada una de las partes del sistema. En cualquier condición de recursos energéticos y de carga a suministrar, el sobredimensionamiento del sistema aumenta su confiabilidad a expensas del costo, mientras que un dimensionamiento insuficiente sacrifica la confiabilidad para disminuir el costo del sistema. Por tanto, conseguir el tamaño óptimo para un sistema, no solo mejora su fiabilidad, sino que también reduce su coste.La experiencia demuestra que el proceso de optimización de sistemas híbridos aislados es más complejo que en los sistemas no híbridos, y no se logra de manera fácil utilizando los procedimientos clásicos de optimización, ya que el problema que debe resolverse tiene multitud de soluciones posibles (distintas combinaciones de paneles fotovoltaicos, aerogeneradores, generadores diésel, baterías de almacenamiento, distintas estrategias de gestión del sistema, etc.), unido al alto grado de variabilidad que presentan los recursos renovables y a que algunos de los componentes de los sistemas presentan características no lineales hacen que exista un gran número de variables que pueden influir en este proceso de optimización.Los objetivos de esta tesis se centran en la optimización de este tipo de sistemas, y han sido: - Analizar la influencia del modelo de batería tipo plomo-ácido utilizado en la optimización de sistemas híbridos aislados con alimentación renovable. - Diseñar un nuevo modelo para optimizar sistemas híbridos aislados temporales con alimentación renovable, durante el periodo específico en el que estará instalado el sistema, optimizando el peso y/o el coste de la instalación temporal. - Diseñar un nuevo modelo para optimizar sistemas híbridos aislados con alimentación renovable, minimizando el coste actual neto y maximizando el índice de desarrollo humano y la creación de empleo. - Diseñar una nueva metodología estocástica-heurística para optimizar sistemas híbridos aislados con alimentación renovable.<br /