A framework of L-HC and AM-MKF for accurate harmonic supportive control schemes

In this paper, an enhanced optimal control technique based on adaptive Maximize-M Kalman filter (AM-MKF) is used. To maximize power extraction from solar PV (Photovoltaic) panel, a learning-based hill climbing (L-HC) algorithm is implemented for a grid integrated solar PV system. For the testing, a three-phase system configuration based on 2-stage topology, and the deployed load on a common connection point (CCP) are considered. The L-HC MPPT algorithm is the modified version of HC (Hill Climbing) algorithm, where issues like, oscillation in steady-state condition and, slow response during dynamic change condition are mitigated. The AM-MKF is an advanced version of KF (Kalman Filter), where for optimal estimation in KF, an AM-M (Adaptive Maximize-M) concept is integrated. The key objective of the novel control strategy is to extract maximum power from the solar panel and to meet the demand of the load. After satisfying the load demand, the rest power is transferred to the grid. However, in the nighttime, the system is used for reactive power support, which mode of operation is known as a DSTATCOM (Distribution Static Compensator). The capability of developed control strategies, is proven through testing on a prototype. During experimentation, different adverse grid conditions, unbalanced load situation and variable solar insolation are considered. In these situations, the satisfactory performances of control techniques prove the effectiveness of the developed control strategy

Comprehensive Review on Detection and Classification of Power Quality Disturbances in Utility Grid With Renewable Energy Penetration

The global concern with power quality is increasing due to the penetration of renewable energy (RE) sources to cater the energy demands and meet de-carbonization targets. Power quality (PQ) disturbances are found to be more predominant with RE penetration due to the variable outputs and interfacing converters. There is a need to recognize and mitigate PQ disturbances to supply clean power to the consumer. This article presents a critical review of techniques used for detection and classification PQ disturbances in the utility grid with renewable energy penetration. The broad perspective of this review paper is to provide various concepts utilized for extraction of the features to detect and classify the PQ disturbances even in the noisy environment. More than 220 research publications have been critically reviewed, classified and listed for quick reference of the engineers, scientists and academicians working in the power quality area

Reliability Enhancing Control Algorithms for Two-Stage Grid-Tied Inverters

In the photovoltaic (PV) generation system, two types of grid-tied inverter systems are usually deployed: the single-stage grid-tied inverter system and the two-stage grid-tied inverter system. In the single-stage grid-tied inverter system, the input of the inverter is directly connected to the PV arrays, while an additional dc-dc stage is inserted between the PV arrays and the dc-ac inverter in the two-stage design. The additional dc-dc stage could provide a stable dc-link voltage to the inverter, which also enables new design possibilities, including the multi-MPPT operation and solar-plus-storage application. Thus, the two-stage grid-tied inverter has been widely used in the PV generation system.As the core component of the PV generation system, the reliability of the grid-tied inverter determines the overall robustness of the system. The two-stage grid-tied inverter system includes three parts: the dc-dc stage, dc-link capacitor, and dc-ac inverter. Thus, the reliability of the two-stage grid-tied inverter relies on the reliability of each part. The dc-dc stage is used to provide a stable dc-link voltage to the inverter. However, when the inverter stage provides constant power to the grid, the load of the dc-dc stage becomes the constant power load (CPL), which will deteriorate the stability of the dc-dc stage. The dc-link capacitor is used to attenuate the voltage ripple on the dc-link and balance the transient power mismatch between the dc-dc stage and the dc-ac stage. However, during the operation of the inverter system, the degradation of the capacitor will reduce the converter reliability, and even result in system failure. The inverter stage is connected to the grid through the output filter, and the LCL type filter has been commonly used due to its superior performance. The resonance of the LCL filter must be properly damped to enhance the inverter stability. However, the grid-side impedance will lead to the resonant frequency drifting of the LCL filter, which will worsen the stability margin of the inverter. Thus, the control design of the two-stage grid-tied inverter system must consider those reliability challenges. In this work, three control algorithms are proposed to solve the reliability challenges. For the dc-dc stage, an uncertainty and disturbance estimator (UDE) based robust voltage control scheme is proposed. The proposed voltage control scheme can actively estimate and compensate for the disturbance of the dc-dc stage. Both the disturbance rejection performance and the stability margin of the dc-dc stage, especially under the CPL, could be enhanced. For the dc-link capacitor, a high-frequency (HF) signal injection based capacitance estimation scheme is proposed. The proposed estimation scheme can monitor the actual dc-link capacitance in real-time. For the inverter stage, an adaptive extremum seeking control (AESC) based LCL filter resonant frequency estimation scheme is proposed. The AESC-based estimation scheme can estimate the resonant frequency of the LCL filter online. All the proposed reliability enhancing control algorithms could enhance the reliability of the two-stage grid-tied inverter system. Detailed theoretical analysis, simulation studies, and comprehensive experimental studies have been performed to validate the effectiveness

Reliability Enhancing Control Algorithms for Two-Stage Grid-Tied Inverters

In the photovoltaic (PV) generation system, two types of grid-tied inverter systems are usually deployed: the single-stage grid-tied inverter system and the two-stage grid-tied inverter system. In the single-stage grid-tied inverter system, the input of the inverter is directly connected to the PV arrays, while an additional dc-dc stage is inserted between the PV arrays and the dc-ac inverter in the two-stage design. The additional dc-dc stage could provide a stable dc-link voltage to the inverter, which also enables new design possibilities, including the multi-MPPT operation and solar-plus-storage application. Thus, the two-stage grid-tied inverter has been widely used in the PV generation system.As the core component of the PV generation system, the reliability of the grid-tied inverter determines the overall robustness of the system. The two-stage grid-tied inverter system includes three parts: the dc-dc stage, dc-link capacitor, and dc-ac inverter. Thus, the reliability of the two-stage grid-tied inverter relies on the reliability of each part. The dc-dc stage is used to provide a stable dc-link voltage to the inverter. However, when the inverter stage provides constant power to the grid, the load of the dc-dc stage becomes the constant power load (CPL), which will deteriorate the stability of the dc-dc stage. The dc-link capacitor is used to attenuate the voltage ripple on the dc-link and balance the transient power mismatch between the dc-dc stage and the dc-ac stage. However, during the operation of the inverter system, the degradation of the capacitor will reduce the converter reliability, and even result in system failure. The inverter stage is connected to the grid through the output filter, and the LCL type filter has been commonly used due to its superior performance. The resonance of the LCL filter must be properly damped to enhance the inverter stability. However, the grid-side impedance will lead to the resonant frequency drifting of the LCL filter, which will worsen the stability margin of the inverter. Thus, the control design of the two-stage grid-tied inverter system must consider those reliability challenges. In this work, three control algorithms are proposed to solve the reliability challenges. For the dc-dc stage, an uncertainty and disturbance estimator (UDE) based robust voltage control scheme is proposed. The proposed voltage control scheme can actively estimate and compensate for the disturbance of the dc-dc stage. Both the disturbance rejection performance and the stability margin of the dc-dc stage, especially under the CPL, could be enhanced. For the dc-link capacitor, a high-frequency (HF) signal injection based capacitance estimation scheme is proposed. The proposed estimation scheme can monitor the actual dc-link capacitance in real-time. For the inverter stage, an adaptive extremum seeking control (AESC) based LCL filter resonant frequency estimation scheme is proposed. The AESC-based estimation scheme can estimate the resonant frequency of the LCL filter online. All the proposed reliability enhancing control algorithms could enhance the reliability of the two-stage grid-tied inverter system. Detailed theoretical analysis, simulation studies, and comprehensive experimental studies have been performed to validate the effectiveness

Renewable Energies for Sustainable Development

In the current scenario in which climate change dominates our lives and in which we all need to combat and drastically reduce the emission of greenhouse gases, renewable energies play key roles as present and future energy sources. Renewable energies vary across a wide range, and therefore, there are related studies for each type of energy. This Special Issue is composed of studies integrating the latest research innovations and knowledge focused on all types of renewable energy: onshore and offshore wind, photovoltaic, solar, biomass, geothermal, waves, tides, hydro, etc. Authors were invited submit review and research papers focused on energy resource estimation, all types of TRL converters, civil infrastructure, electrical connection, environmental studies, licensing and development of facilities, construction, operation and maintenance, mechanical and structural analysis, new materials for these facilities, etc. Analyses of a combination of several renewable energies as well as storage systems to progress the development of these sustainable energies were welcomed

DC & Hybrid Micro-Grids

This book is a printed version of the papers published in the Special Issue “DC & Hybrid Microgrids” of Applied Sciences. This Special Issue, co-organized by the University of Pisa, Italy and Østfold University College in Norway, has collected nine papers and the editorial, from 28 submitted, with authors from Asia, North America and Europe. The published articles provide an overview of the most recent research advances in direct current (DC) and hybrid microgrids, exploiting the opportunities offered by the use of renewable energy sources, battery energy storage systems, power converters, innovative control and energy management strategies

Advanced Solutions for Renewable Energy Integration into the Grid Addressing Intermittencies, Harmonics and Inertial Response

Numerous countries are trying to reach almost 100\% renewable penetration. Variable renewable energy (VRE), for instance wind and PV, will be the main provider of the future grid. The efforts to decrease the greenhouse gasses are promising on the current remarkable growth of grid connected photovoltaic (PV) capacity. This thesis provides an overview of the presented techniques, standards and grid interface of the PV systems in distribution and transmission level. This thesis reviews the most-adopted grid codes which required by system operators on large-scale grid connected Photovoltaic systems. The adopted topologies of the converters, the control methodologies for active - reactive power, maximum power point tracking (MPPT), as well as their arrangement in solar farms are studied. The unique L(LCL)2 filter is designed, developed and introduced in this thesis. This study will help researchers and industry users to establish their research based on connection requirements and compare between different existing technologies. Another, major aspect of the work is the development of Virtual Inertia Emulator (VIE) in the combination of hybrid energy storage system addressing major challenges with VRE implementations. Operation of a photovoltaic (PV) generating system under intermittent solar radiation is a challenging task. Furthermore, with high-penetration levels of photovoltaic energy sources being integrated into the current electric power grid, the performance of the conventional synchronous generators is being changed and grid inertial response is deteriorating. From an engineering standpoint, additional technical measures by the grid operators will be done to confirm the increasingly strict supply criteria in the new inverter dominated grid conditions. This dissertation proposes a combined virtual inertia emulator (VIE) and a hybrid battery-supercapacitor-based energy storage system . VIE provides a method which is based on power devices (like inverters), which makes a compatible weak grid for integration of renewable generators of electricity. This method makes the power inverters behave more similar to synchronous machines. Consequently, the synchronous machine properties, which have described the attributes of the grid up to now, will remain active, although after integration of renewable energies. Examples of some of these properties are grid and generator interactions in the function of a remote power dispatch, transients reactions, and the electrical outcomes of a rotating bulk mass. The hybrid energy storage system (HESS) is implemented to smooth the short-term power fluctuations and main reserve that allows renewable electricity generators such as PV to be considered very closely like regular rotating power generators. The objective of utilizing the HESS is to add/subtract power to/from the PV output in order to smooth out the high frequency fluctuations of the PV power, which may occur due to shadows of passing cloud on the PV panels. A control system designed and challenged by providing a solution to reduce short-term PV output variability, stabilizing the DC link voltage and avoiding short term shocks to the battery in terms of capacity and ramp rate capability. Not only could the suggested system overcome the slow response of battery system (including dynamics of battery, controller, and converter operation) by redirecting the power surges to the supercapacitor system, but also enhance the inertial response by emulating the kinetic inertia of synchronous generator

Cuban energy system development – Technological challenges and possibilities

This eBook is a unique scientific journey to the changing frontiers of energy transition in Cuba focusing on technological challenges of the Cuban energy transition. The focus of this milestone publication is on technological aspects of energy transition in Cuba. Green energy transition with renewable energy sources requires the ability to identify opportunities across industries and services and apply the right technologies and tools to achieve more sustainable energy production systems. The eBook is covering a large diversity of Caribbean country´s experiences of new green technological solutions and applications. It includes various technology assessments of energy systems and technological foresight analyses with a special focus on Cuba