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3 pages, 178 KiB

Open AccessEditorial

Optimal Control of Hybrid Systems and Renewable Energies

by Michela Robba and Mansueto Rossi

Energies 2022, 15(1), 78; https://doi.org/10.3390/en15010078 - 23 Dec 2021

Cited by 3 | Viewed by 1669

Abstract

International policies for sustainable development have led to an increase in distributed power production based on renewable resources [...] Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

Research

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23 pages, 6650 KiB

Open AccessArticle

A Building Energy Management System Based on an Equivalent Electric Circuit Model

by Giovanni Bianco, Stefano Bracco, Federico Delfino, Lorenzo Gambelli, Michela Robba and Mansueto Rossi

Energies 2020, 13(7), 1689; https://doi.org/10.3390/en13071689 - 3 Apr 2020

Cited by 16 | Viewed by 2865

Abstract

In recent decades, many EU and national regulations have been issued in order to increase the energy efficiency in different sectors and, consequently, to reduce environmental pollution. In the building sector, energy efficiency interventions are usually based on the use of innovative insulated [...] Read more.

In recent decades, many EU and national regulations have been issued in order to increase the energy efficiency in different sectors and, consequently, to reduce environmental pollution. In the building sector, energy efficiency interventions are usually based on the use of innovative insulated materials and on the installation of cogeneration and tri-generation units, as well as solar technologies. New and retrofitted buildings are more and more commonly being called “smart buildings”, since they are characterized by the installation of electric and thermal power generation units, energy storage systems, and flexible loads; the presence of such technologies determines the necessity of installing Building Energy Management Systems (BEMSs), which are used to optimally manage their operation. The present paper proposes a BEMS for a smart building, equipped with plants based on renewables (photovoltaics, solar thermal panels, and geothermal heat pump), where the heating and cooling demand are satisfied by a Heating, Ventilation and Air Conditioning System (HVAC) fed by a geothermal heat pump. The developed BEMS is composed of two different modules: an optimization tool used to optimally manage the HVAC plant, in order to guarantee a desired level of comfort inside rooms, and a simulation tool, based on an equivalent electric circuit model and used to evaluate the thermal dynamic behavior of the building. The paper describes the two modules and shows the main results of the validation phase that has been conducted on a real test-case represented by the Smart Energy Building (SEB) located at the Savona Campus of the University of Genoa, Italy. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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37 pages, 9568 KiB

Open AccessArticle

Operational Simulation Environment for SCADA Integration of Renewable Resources

by Diego Francisco Larios, Enrique Personal, Antonio Parejo, Sebastián García, Antonio García and Carlos Leon

Energies 2020, 13(6), 1333; https://doi.org/10.3390/en13061333 - 13 Mar 2020

Cited by 4 | Viewed by 3660

Abstract

The complexity of power systems is rising mainly due to the expansion of renewable energy generation. Due to the enormous variability and uncertainty associated with these types of resources, they require sophisticated planning tools so that they can be used appropriately. In this [...] Read more.

The complexity of power systems is rising mainly due to the expansion of renewable energy generation. Due to the enormous variability and uncertainty associated with these types of resources, they require sophisticated planning tools so that they can be used appropriately. In this sense, several tools for the simulation of renewable energy assets have been proposed. However, they are traditionally focused on the simulation of the generation process, leaving the operation of these systems in the background. Conversely, more expert SCADA operators for the management of renewable power plants are required, but their training is not an easy task. SCADA operation is usually complex, due to the wide set of information available. In this sense, simulation or co-simulation tools can clearly help to reduce the learning curve and improve their skills. Therefore, this paper proposes a useful simulator based on a JavaScript engine that can be easily connected to any renewable SCADAs, making it possible to perform different simulated scenarios for novel operator training, as if it were a real facility. Using this tool, the administrators can easily program those scenarios allowing them to sort out the lack of support found in setting up facilities and training of novel operator tasks. Additionally, different renewable energy generation models that can be implemented in the proposed simulator are described. Later, as a use example of this tool, a study case is also performed. It proposes three different wind farm generation facility models, based on different turbine models: one with the essential generation turbine function obtained from the manufacturer curve, another with an empirical model using monotonic splines, and the last one adding the most important operational states, making it possible to demonstrate the usefulness of the proposed simulation tool. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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14 pages, 3994 KiB

Open AccessArticle

Economy Mode Setting Device for Wind-Diesel Power Plants

by Andrey Dar’enkov, Elena Sosnina, Andrey Shalukho and Ivan Lipuzhin

Energies 2020, 13(5), 1274; https://doi.org/10.3390/en13051274 - 10 Mar 2020

Cited by 5 | Viewed by 2241

Abstract

The article is devoted to the problem of reducing fuel consumption in a diesel generator set (DGS) as a part of a wind-diesel power plant (WDPP). The object of the research is a variable speed DGS. The goal is to develop the WDPP [...] Read more.

The article is devoted to the problem of reducing fuel consumption in a diesel generator set (DGS) as a part of a wind-diesel power plant (WDPP). The object of the research is a variable speed DGS. The goal is to develop the WDPP intelligent control system, providing an optimal shaft speed of an internal combustion engine (ICE). The basis of the intelligent control system is an economy mode setting device (EMSD), which controls the fuel supply to the ICE. The functional chart of EMSD has been presented. The main EMSD blocks contain a controller and an associative memory block. The associative memory block is a software model of an artificial neural network that determines the optimal shaft speed of the ICE. An algorithm for the WDPP intelligent control system has been developed and tested using the WDPP Simulink model. The EMSD prototype has been created, and its research has been conducted. Dependences of the change in specific and absolute fuel consumption on the load power have been obtained for two 4 kW DGS: with constant rotation speed and variable rotation speed DGS with EMSD. It has been established that the use of EMSD in the mode of low loads allow one to reduce fuel consumption by almost 30%. The error in determining the optimal engine speed using EMSD prototype is not more than 15%. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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23 pages, 7395 KiB

Open AccessArticle

Optimal Control of Multiple Microgrids and Buildings by an Aggregator

by Giulio Ferro, Riccardo Minciardi, Luca Parodi, Michela Robba and Mansueto Rossi

Energies 2020, 13(5), 1058; https://doi.org/10.3390/en13051058 - 27 Feb 2020

Cited by 13 | Viewed by 2252

Abstract

The electrical grid has been changing in the last decade due to the presence of renewables, distributed generation, storage systems, microgrids, and electric vehicles. The introduction of new legislation and actors in the smart grid’s system opens new challenges for the activities of [...] Read more.

The electrical grid has been changing in the last decade due to the presence of renewables, distributed generation, storage systems, microgrids, and electric vehicles. The introduction of new legislation and actors in the smart grid’s system opens new challenges for the activities of companies, and for the development of new energy management systems, models, and methods. A new optimization-based bi-level architecture is proposed for an aggregator of consumers in the balancing market, in which incentives for local users (i.e., microgrids, buildings) are considered, as well as flexibility and a fair assignment in reducing the overall load. At the lower level, consumers try to follow the aggregator’s reference values and perform demand response programs to contain their costs and satisfy demands. The approach is applied to a real case study. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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24 pages, 7157 KiB

Open AccessArticle

Energy-Storage-Based Smart Electrical Infrastructure and Regenerative Braking Energy Management in AC-Fed Railways with Neutral Zones

by Zhixuan Gao, Qiwei Lu, Cong Wang, Junqing Fu and Bangbang He

Energies 2019, 12(21), 4053; https://doi.org/10.3390/en12214053 - 24 Oct 2019

Cited by 18 | Viewed by 2499

Abstract

This paper presents a modified power supply system based on the current alternating current (AC)-fed railways with neutral zones that can further improve the eco-friendliness and smart level of railways. The modified system complements the existing infrastructure with additional energy-storage-based smart electrical infrastructure. [...] Read more.

This paper presents a modified power supply system based on the current alternating current (AC)-fed railways with neutral zones that can further improve the eco-friendliness and smart level of railways. The modified system complements the existing infrastructure with additional energy-storage-based smart electrical infrastructure. This infrastructure comprises power electronic devices with energy storage system connected in parallel to both sides of each neutral zone in the traction substations, power electronic devices connected in parallel to both sides of each neutral zone in section posts, and an energy management system. The description and functions of such a modified system are outlined in this paper. The system allows for the centralized- and distributed-control of different functions via an energy management system. In addition, a control algorithm is proposed, based on the modified system for regenerative braking energy utilization. This would ensure that all the regenerative braking energy in the whole railway electrical system is used more efficiently. Finally, a modified power supply system with eight power supply sections is considered to be a case study; furthermore, the advantages of the proposed system and the effectiveness of the proposed control algorithm are verified. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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19 pages, 10877 KiB

Open AccessFeature PaperArticle

A Comprehensive Inverter-BESS Primary Control for AC Microgrids

by Michele Fusero, Andrew Tuckey, Alessandro Rosini, Pietro Serra, Renato Procopio and Andrea Bonfiglio

Energies 2019, 12(20), 3810; https://doi.org/10.3390/en12203810 - 9 Oct 2019

Cited by 34 | Viewed by 4187

Abstract

This paper proposes the design of a comprehensive inverter-BESS primary control capable of providing satisfactory performances both in grid-connected and islanded configurations as required by international standards and grid codes, such as IEEE Std. 1547. Such control guarantees smooth and fast dynamic behavior [...] Read more.

This paper proposes the design of a comprehensive inverter-BESS primary control capable of providing satisfactory performances both in grid-connected and islanded configurations as required by international standards and grid codes, such as IEEE Std. 1547. Such control guarantees smooth and fast dynamic behavior of the converter in islanded configuration as well as fast power control and voltage-frequency support in grid-connected mode. The performances of the proposed primary control are assessed by means of EMT (ElectroMagnetic Transients) simulations in the dedicated software DIgSILENT PowerFactory^® (Germany, Gomaringen) . The simulation results show that the proposed BESS (Battery Energy Storage System) primary control is able to regulate frequency and voltage in Grid-Forming mode independently of the number of paralleled generators. This is achieved adopting a virtual generator technique which presents several advantages compared to the conventional one. Moreover, the proposed control can be switched to Grid-Support mode in order to provide fast control actions to allow frequency and voltage support as well as power control following the reference signals from the secondary level. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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15 pages, 2187 KiB

Open AccessArticle

A Comparison of the Dynamic Performance of Conventional and Ternary Pumped Storage Hydro

by Soumyadeep Nag, Kwang Y. Lee and D. Suchitra

Energies 2019, 12(18), 3513; https://doi.org/10.3390/en12183513 - 12 Sep 2019

Cited by 17 | Viewed by 4056

Abstract

With decreasing costs of renewable energy harvesting devices, penetration of solar panels and wind turbines have increased manifold. Under such high levels of penetration, coping with increased intermittency and unpredictability and maintaining power system resiliency under reduced inertia conditions has become a critical [...] Read more.

With decreasing costs of renewable energy harvesting devices, penetration of solar panels and wind turbines have increased manifold. Under such high levels of penetration, coping with increased intermittency and unpredictability and maintaining power system resiliency under reduced inertia conditions has become a critical issue. Pumped storage hydro (PSH) is the most matured and economic form of storage that can serve the purpose of capacity for over 4 to 8 h. However, to increase network inertia and add required flexibility to low inertia power systems, significant paradigm shifting modifications have been engineered to result in the development of Ternary PSH (TPSH). In this paper a test system to consider governor interaction is constructed. The dynamic models of conventional PSH (CPSH) and TPSH are constructed and integrated to the test system to examine the effect of CPSH and TPSH in the hydraulic short circuit (TPSH-HSC). The ability and the effect of mode change (from pump to turbine) without the loss synchronism of TPSH has also been examined. Results display the superior capability and effect of TPSH with its HSC capability to contribute to frequency regulation during pumping mode and the effect of rapid mode change, as compared to its primitive alternative, CPSH. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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12 pages, 2303 KiB

Open AccessArticle

A Feedback Control Loop Optimisation Methodology for Floating Offshore Wind Turbines

by Joannes Olondriz, Josu Jugo, Iker Elorza and Santiago Alonso-Quesada and Aron Pujana-Arrese

Energies 2019, 12(18), 3490; https://doi.org/10.3390/en12183490 - 10 Sep 2019

Cited by 10 | Viewed by 2744

Abstract

Wind turbines usually present several feedback control loops to improve or counteract some specific performance or behaviour of the system. It is common to find these multiple feedback control loops in Floating Offshore Wind Turbines where the system perferformance is highly influenced by [...] Read more.

Wind turbines usually present several feedback control loops to improve or counteract some specific performance or behaviour of the system. It is common to find these multiple feedback control loops in Floating Offshore Wind Turbines where the system perferformance is highly influenced by the platform dynamics. This is the case of the Aerodynamic Platform Stabiliser and Wave Rejection feedback control loops which are complementaries to the conventional generator speed PI control loop when it is working in an above rated wind speed region. The multiple feedback control loops sometimes can be tedious to manually improve the initial tuning. Therefore, this article presents a novel optimisation methodology based on the Monte Carlo method to automatically improve the manually tuned multiple feedback control loops. Damage Equivalent Loads are quantified for minimising the cost function and automatically update the control parameters. The preliminary results presented here show the potential of this novel optimisation methodology to improve the mechanical fatigue loads of the desired components whereas maintaining the overall performance of the wind turbine system. This methodology provides a good balance between the computational complexity and result effectiveness. The study is carried out with the fully coupled non-linear NREL 5-MW wind turbine model mounted on the ITI Energy’s barge and the FASTv8 code. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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23 pages, 9828 KiB

Open AccessArticle

Control of Hybrid Diesel/PV/Battery/Ultra-Capacitor Systems for Future Shipboard Microgrids

by Muhammad Umair Mutarraf, Yacine Terriche, Kamran Ali Khan Niazi, Fawad Khan, Juan C. Vasquez and Josep M. Guerrero

Energies 2019, 12(18), 3460; https://doi.org/10.3390/en12183460 - 7 Sep 2019

Cited by 24 | Viewed by 5029

Abstract

In recent times, concerns over fossil fuel consumption and severe environmental pollution have grabbed attention in marine vessels. The fast development in solar technology and the significant reduction in cost over the past decade have allowed the integration of solar technology in marine [...] Read more.

In recent times, concerns over fossil fuel consumption and severe environmental pollution have grabbed attention in marine vessels. The fast development in solar technology and the significant reduction in cost over the past decade have allowed the integration of solar technology in marine vessels. However, the highly intermittent nature of photovoltaic (PV) modules might cause instability in shipboard microgrids. Moreover, the penetration is much more in the case of utilizing PV panels on ships due to the continuous movement. This paper, therefore, presents a frequency sharing approach to smooth the effect of the highly intermittent nature of PV panels integrated with the shipboard microgrids. A hybrid system based on an ultra-capacitor and a lithium-ion battery is developed such that high power and short term fluctuations are catered by an ultra-capacitor, whereas long duration and high energy density fluctuations are catered by the lithium-ion battery. Further, in order to cater for the fluctuations caused by weather or variation in sea states, a battery energy storage system (BESS) is utilized in parallel to the dc-link capacitor using a buck-boost converter. Hence, to verify the dynamic behavior of the proposed approach, the model is designed in MATLAB/SIMULINK. The simulation results illustrate that the proposed model helps to smooth the fluctuations and to stabilize the DC bus voltage. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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22 pages, 2903 KiB

Open AccessArticle

Hybrid Nonlinear MPC of a Solar Cooling Plant

by Eduardo F. Camacho, Antonio J. Gallego, Juan M. Escaño and Adolfo J. Sánchez

Energies 2019, 12(14), 2723; https://doi.org/10.3390/en12142723 - 16 Jul 2019

Cited by 11 | Viewed by 2396

Abstract

Solar energy for cooling systems has been widely used to fulfill the growing air conditioning demand. The advantage of this approach is based on the fact that the need of air conditioning is usually well correlated to solar radiation. These kinds of plants [...] Read more.

Solar energy for cooling systems has been widely used to fulfill the growing air conditioning demand. The advantage of this approach is based on the fact that the need of air conditioning is usually well correlated to solar radiation. These kinds of plants can work in different operation modes resulting on a hybrid system. The control approaches designed for this kind of plant have usually a twofold goal: (a) regulating the outlet temperature of the solar collector field and (b) choosing the operation mode. Since the operation mode is defined by a set of valve positions (discrete variables), the overall control problem is a nonlinear optimization problem which involves discrete and continuous variables. This problems are difficult to solve within the normal sampling times for control purposes (around 20–30 s). In this paper, a two layer control strategy is proposed. The first layer is a nonlinear model predictive controller for regulating the outlet temperature of the solar field. The second layer is a fuzzy algorithm which selects the adequate operation mode for the plant taken into account the operation conditions. The control strategy is tested on a model of the plant showing a proper performance. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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18 pages, 4516 KiB

Open AccessArticle

A Firefly Algorithm Optimization-Based Equivalent Consumption Minimization Strategy for Fuel Cell Hybrid Light Rail Vehicle

by Han Zhang, Jibin Yang, Jiye Zhang, Pengyun Song and Xiaohui Xu

Energies 2019, 12(14), 2665; https://doi.org/10.3390/en12142665 - 11 Jul 2019

Cited by 15 | Viewed by 2518

Abstract

To coordinate multiple power sources properly, this paper presents an optimal control strategy for a fuel cell/battery/supercapacitor light rail vehicle. The proposed strategy, which uses the firefly algorithm to optimize the equivalent consumption minimization strategy, improves the drawback that the conventional equivalent consumption [...] Read more.

To coordinate multiple power sources properly, this paper presents an optimal control strategy for a fuel cell/battery/supercapacitor light rail vehicle. The proposed strategy, which uses the firefly algorithm to optimize the equivalent consumption minimization strategy, improves the drawback that the conventional equivalent consumption minimization strategy takes insufficient account of the global performance for the vehicle. Moreover, the strategy considers the difference between the two sets of optimized variables. The optimization objective is to minimize the daily operating cost of the vehicle, which includes the total fuel consumption, initial investment, and cycling costs of power sources. The selected case study is a 100% low-floor light rail vehicle. The advantages of the proposed strategy are investigated by comparison with the operating mode control, firefly algorithm-based operating mode control, and equivalent consumption minimization strategy. In contrast to other methods, the proposed strategy shows cost reductions of up to 39.62% (from operating mode control), 18.28% (from firefly algorithm-based operating mode control), and 13.81% (from equivalent consumption minimization strategy). In addition, the proposed strategy can reduce fuel consumption and increase the efficiency of the fuel cell system. Full article

(This article belongs to the Special Issue Optimal Control of Hybrid Systems and Renewable Energies)

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