Stand-alone Hybrid Power System Research Articles

Stand-alone PV-SOFC-battery power system based on ANFIS controller for electric vehicle charging

Purpose This study aims to offer a hybrid stand-alone system for electric vehicle (EV) charging stations (CS), an emerging power scheme due to the availability of renewable and environment-friendly energy sources. This paper presents the analysis of a photovoltaic (PV) with an adaptive neuro-fuzzy inference system (ANFIS) algorithm, solid oxide fuel cell (SOFC) and a battery storage scheme incorporated for EV CS in a stand-alone mode. In previous studies, either the hydrogen fuel of SOFC or the irradiance is controlled using artificial neural network. These parameters are not controlled simultaneously using an ANFIS-based approach. The ANFIS-based stand-alone hybrid system controlling both the fuel flow of SOFC and the irradiance of PV is discussed in this paper. Design/methodology/approach The ANFIS algorithm provides an efficient estimation of maximum power (MP) to the nonlinear voltage–current characteristics of a PV, integrated with a direct current–direct current (DC–DC) converter to boost output voltage up to 400 V. The issue of fuel starvation in SOFC due to load transients is also mitigated using an ANFIS-based fuel flow regulator, which robustly provides fuel, i.e. hydrogen per necessity. Furthermore, to ensure uninterrupted power to the CS, PV is integrated with a SOFC array, and a battery storage bank is used as a backup in the current scenario. A power management system efficiently shares power among the aforesaid sources. Findings A comprehensive simulation test bed for a stand-alone power system (PV cells and SOFC) is developed in MATLAB/Simulink. The adaptability and robustness of the proposed control paradigm are investigated through simulation results in a stand-alone hybrid power system test bed. Originality/value The simulation results confirm the effectiveness of the ANFIS algorithm in a stand-alone hybrid power system scheme.

Bağımsız Bir Hibrit Güç Sisteminin Tasarımı ve Akıllı MPPT Algoritmaları ile Optimizasyon Kontrolü

In this paper, a stand-alone hybrid power system has been proposed using both: photovoltaic generator (PVG) and permanent magnets synchronous generator (PMSG), integrated with a lithium-type battery connected to the DC bus. The improvement of performance and reliability of the overall system are guaranteed. For this aim, the efficiency of the PVG system can be enhanced firstly by using two MPPT's techniques, such as the Perturb and Observe (P&O) method and the Fuzzy Logic Control (FLC) approach. The Genetic Algorithms (GA’s), using the principles of evolution, natural selection, and genetic mutation, are then introduced to address difficulties in the adjustment of the FLC gains. A lithium-ion battery model is presented to ensure stability and energy storage. Furthermore, the model of the wind energy conversion system (WECS) based on PMSG is presented. Hence, the control by the gradient method, allowing designing an MPPT based on the delivered power and mechanical speed of the generator. Both sources are connected to the grid via a two-level voltage source inverter controlled by Space Vector Modulation (SVM) technique. Finally, simulation results obtained using MATLAB / SIMULINK software proved the effectiveness of proposed control strategies with high performance which is manifested clearly when the suggested controllers employed and shed light on the performance of the stand-alone hybrid system.

Mountain gazelle optimizer for standalone hybrid power system design incorporating a type of incentive-based strategies

The main objective of this research study is to improve the performance of a standalone hybrid power system (SHPS) that consists of photovoltaic modules (PVMs), wind turbines (WTs), battery system (BS), and diesel engine (DE). The emphasis is on optimizing the system's design by incorporating demand response strategies (DRSs). Incorporating these strategies into the system can enhance system performance, stability, and profitability while also reducing the capacity of SHPS components and, consequently, lowering consumers' bills. To achieve this objective, the sizing model incorporates a novel indicator called the load variation factor (LVF). This paper assesses and contrasts various scenarios, including SHPS without DRS, with DRS, and with DRS but no DE. In this article, interruptible/curtailable (I/C) as one of the DRSs is incorporated into the model used for sizing issues. A newly developed optimization algorithm called the mountain gazelle optimizer (MGO) is utilized for the multi-objective design of the proposed SHPS. The utilization of MGO will facilitate achieving the lowest possible values for each of the following: cost of energy (COE), loss of power supply probability (LPSP), and carbon dioxide (CO2) emissions. This work introduces a mathematical model for the entire system, which is subsequently simulated using MATLAB software. The results reveal that among all the scenarios analysed, scenario iii — which has an LVF of 30% — is the most cost-effective. It has the lowest COE, at 0.2334 $/kWh, hence the lowest net present cost (NPC), at 6,836,445.5 $.

Research into the operating modes of a stand-alone dual-channel hybrid power system

<abstract> <p>The article describes the development and simulation of a stand-alone hybrid power system based on a variable-speed diesel generator and a hydrogen fuel cell generation system. The goal of the research was to investigate the electromagnetic processes of this power system, which supplies power to autonomous energy consumers with varying load demand. MATLAB Simulink was used to simulate the proposed hybrid power system and check its operating capacity. The results of the simulation include the dependencies of current and voltage changes in the critical components of the hybrid system at stepwise load rate changes. In the future, the developed models and simulation results will allow researchers to select semiconductor devices and create microprocessor-based control systems for electric power installations that meet specific requirements. The dual-channel power system can provide a required power output of 3 kW when powered by a diesel generator and 1 kW when powered by a hydrogen fuel cell. At the same time, the total harmonic distortion (THD) at a load between 100 W and 3 kW varies within acceptable limits between 3.6% and 4.4%. It is worth noting that these higher power complexes can be incorporated into stand-alone electrical grids as well as centralized distribution systems for power deficit compensation during peak loads.</p> </abstract>

A New Soft Computing Fuzzy Logic Frequency Regulation Scheme for Two Area Hybrid Power Systems

Modern renewable energy power system designs provide significant application benefits, but they also produce losses. The total generation, total load demand, and system losses must be balanced in order for this structured power system to operate reliably. The actual and reactive power balances are disturbed as a result of changes in load demand. System frequency and tie line interchange power deviate from their planned values as a result of this. A high system frequency deviation can cause the system to crash. In that case, multiple connect area systems use intelligent load frequency control techniques to deliver dependable and high-quality frequency and tie line power flow. Here, a standalone hybrid power system is taken into consideration, with generated power and frequency being controlled intelligently. In addition to the unpredictable nature of the wind, frequent adjustments in the load profile can produce sizeable and detrimental power variations. The output power of such renewable sources may fluctuate to the point that it causes significant frequency and voltage changes in the grid. An intelligent approach recently proposed to address the load frequency control (LFC) issue of an interconnected power system is known as fuzzy logic PID controller (FLPIDC). Standard proportional integral derivative (PID) controllers are used to control each section of the system.

A case study of stand-alone hybrid power systems for a data center using HOMER and DIgSILENT

The number of mega data centers is steadily expanding as the cloud business expands. The data center consumes heavy electrical power because of their structural and equipment characteristics (e.g., workstations and cooling equipment). The mega data center becomes a microgrid (e.g., islanding operation). So, a lot of researchers have proposed the architecture design of a green energy data center to solve the heavy energy consumption problem and to reduce the emission release. For example, the goal of a green energy data center is to maximize energy efficiency while reducing environmental impacts (e.g., the reduction of greenhouse gases). So, the goal of this study is to design the most effective power system for a stand-alone hybrid green data center at the aspects of energy savings and the reliable operation. The ideal architecture of a stand-alone data center powered by renewable energy is initially designed by the HOMER program. Then, the steady-state and transient responses of a data center that functions as an island microgrid using DIgSILENT© Power Factory are examined.

Evaluating the Technical and Economic Feasibility of a Hybrid Renewable Energy System for Off-grid

<p class="15">This study describes the best hybrid energy system in terms of emissions, cost, and other factors. All the computations performed by HOMER Pro. A standalone hybrid power system model is suggested in this study. The suggested concept combines diesel generation with PV and Wind energy sources. The National Aeronautics and Space Administration (NASA) provided the data for simulation in HOMER to determine system performance. To reduce dependency on either conventional energy or renewable energy sources, a hybrid renewable energy system may be employed. Studies have shown that the suggested approach and the optimization technique for sizing standalone hybrid power systems both settle really well. The study aim is to optimize the size and expense of a renewable energy system at the chosen location in order to satisfy the electrical demand. The evaluation of the hybrid systems is based on the net present cost (NPC), levelized cost of energy (COE), initial cost, operating cost, and renewable fraction. The results support the use of RES at the chosen location, with the PV-Wind-Diesel generator system emerging as the most cost-effective RES with a COE of 0.2424 $/kWh. The outcomes are in favor of using a hybrid renewable system.</p>

Techno-economic comparison of standalone solar PV and hybrid power systems for remote outdoor telecommunication sites in northern Ghana

Telecommunication services have continued to evolve to meet the ever-changing bandwidth demand requirements. The electricity grid network of Ghana is faced with challenges, including low voltages, a lack of quick fault response teams, and the proximity to specific locations. Using diesel generators to address the shortfall in grid supply is expensive and has implications for greenhouse gas emissions. This study evaluated the technical and economic benefits of using a standalone solar photovoltaic (PV) system, hybrid (Solar PV/diesel), conventional diesel generators (DG), and grid extension to power an off-grid outdoor telecommunication site. Power solutions configurations were simulated using hybrid optimization of multiple electric renewables (HOMER). The study found the optimum design to be a standalone solar PV/battery system with 56.3 kW solar PV array and Sixty (60) pieces of 12 V SAGM batteries of 135 Ah. The optimum design had a net present cost (NPC) of US$ 88,176.00 and a cost of energy (COE) of US$ 0.321/kWh. The COE and the NPC of the optimum system were approximately 50% less than the design with DG only, which could significantly impact service tariff and improve access to digital connectivity. The COE from the solar PV/battery system is not competitive with the grid power supply (COE = US$0.12). However, considering the electric distance limit or breakeven distance of 4.51km for grid extension, the solar PV/battery is preferred. Therefore, the stakeholders in providing power solutions to off-grid locations should consider solar PV technology.

Techno-economic optimization of standalone hybrid power systems in context of intelligent computational multi-objective algorithms

The use of renewable energy (RE) for meeting some load power demand in the present global developmental dealings is realistically unavoidable. However, many challenges conspicuously stand the way of RE penetration into the global power sector. Some of the perceived problems require aggressive research attentions. The utilization of single RE energy structure for the supply of electricity in off-grid isolated communities is usually not a technically dependable system with to regards reliability, security and stability. The core challenge is usually connected to some spontaneous variable weather conditions. It is based on this perspective that the implementation of integrated hybrid RE becomes a promising solution for mitigation of RE intermittent behaviors. In this study, an autonomous hybrid energy system was examined based on simulations for optimal sizing configurations of solar photovoltaic (PV), wind turbine (WT), diesel generator (DG) and battery storage (BS) system. Modern intelligent optimization algorithms of Ant Colony Optimization (ACO), Flower Pollination Algorithm (FPA), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) were applied for providing solutions to the set of selected focal technoeconomic objectives in the framework of this study. Compare with others, FPA provided better results in terms of the net present cost (NPC), cost of energy (COE) and deficit power supply probability (DPSP). The proposed hybrid power systems are configured in four different scenarios: PV/BS, PV/DG/BS, PV/WT/BS and PV/WT/DG/BS. It was consequently established that the configuration of PV/DG/BS with NPC of $85112.08, COE of 0.145 $/kWh and zero DPSP gave the best overall technoeconomic results through the FPA optimization technique.

Hierarchical optimization of policy and design for standalone hybrid power systems considering lifecycle carbon reduction subsidy

To achieve the target of carbon neutrality, the present work proposes a lifecycle carbon reduction subsidy policy to promote the exploitation of renewable energy technologies in remote areas. The hierarchical optimization of policy and design for a standalone hybrid renewable energy system is further conducted based on the proposed subsidy policy. The upper-level policy optimization model aims to maximize the renewable energy fraction and minimize the subsidy expenses borne by the government simultaneously, and the lower-level design optimization model aims to minimize the net present cost borne by the system operator. Four meta-heuristic algorithms coupled with a standard iterative method are employed to solve the hierarchical optimization problem, and their performances are comprehensively assessed in terms of convergence, robustness, and computational efficiency. Besides, an improved K-means clustering algorithm along with a tailored optimal K-value selection strategy is employed for scenario reduction. The results of the case study show that: (ⅰ) teaching-learning-based optimization performs the best convergence and robustness as it achieves the balance of exploration and exploitation. (ⅱ) the nexus between policy and system design presents a piecewise pattern, implying that the system configuration will change significantly only when the subsidy policy exceeds a certain threshold. (ⅲ) the proposed subsidy policy is expected to increase the renewable energy fraction to 99.23% and reduce the lifecycle carbon emissions by 80.7%. Overall, the proposed subsidy policy and its impact mechanism on system design can provide theoretical support for the government to formulate tailored policies for different preferences, and the proposed optimization framework and methodology can be directly extended to practical applications.

Technical-environmental-economic evaluation of biomass-based hybrid power system with energy storage for rural electrification

In recent years, higher penetrations of renewable energy generations helped persuade sustainable energy and environmental targets, although their intermittent and fluctuated nature raised technical challenges. However, hybrid power system can minimize these technical issues by integrating flexible generation capable renewable energy sources like biomass. This study deals with optimizing grid-integrated and stand-alone biomass-based hybrid power system for the energy demand of a rural region containing poultry farms. Besides solar and wind energy, energy storage integration is evaluated regarding overall technical-environmental-economic performance, considering the actual manure potential using HOMER Pro. In addition, sensitivity analyses are performed, considering the estimated load and inflations using an artificial neural network method. Using biomass and solar hybrid options offers more autonomous, environmentally friendly, and economic advantages. Biomass-based hybrid power system with solar energy reduced net present cost by around 12% and increased renewable fraction by 7%, and grid-connected options can provide 88.9% renewable fraction. In addition, the energy storage integration increased renewable fraction by around 10% and reduced excess energy by 16%. The proposed biomass-based hybrid power system achieves cost-effective sizing of solar or wind-based hybrid systems, empowers the reliability of renewable energy and presents good consistency of decarbonization targets.

Optimal Management Energy System and Control Strategies for Isolated Hybrid Solar-Wind-Battery-Diesel Power System

This paper proposes optimal control strategies of a standalone Hybrid Power System (HPS) to supply sustainable and optimal energy to an isolated site with improved quality of electrical energy. A topology of Isolated Hybrid Power System (IHPS) is proposed, consists of: a Photovoltaic System (PVS), a Wind Energy Conversion System (WECS), electronic power devices controlled to maximize energy production from renewable sources and to maintain the constant DC-link voltage, a Battery Energy Storage System (BESS), Diesel Generator (DG), and a Pulse Width Modulation (PWM) Voltage Source Inverter (VSI) located at the load-side end. In addition, a novel control strategy has been proposed, in this work, to maximize the power from the PVS. This presented strategy, based on the combination between Perturb and Observe (P&O) algorithm and the Fuzzy PI Controller (FPIC), presents a good performance, especially in the dynamic state compared to the classical algorithm P&O. A supervisory control algorithm has been elaborated to manage the energy flows between the devices of the hybrid system to make the decision of the optimal operating mode in order to ensure a continuous supply of the load with minimum usage of batteries and DG. The simulation results developed in the Matlab/Simulink environment are applied to show the efficiency and performance of the proposed control strategies in terms of power optimization and energy management. Doi: 10.28991/esj-2021-01262 Full Text: PDF

Cost-reliability analysis of hybrid pumped-battery storage for solar and wind energy integration in an island community

This paper presents a mathematical model for estimating the optimal sizing and assessing a standalone hybrid power system's performance entirely based on variable renewable energy sources and coupled with a hybrid energy storage system. This study evaluates how different levels of the main components' capital cost and the loss of power supply probability would affect the cost of energy and the power system's optimal sizing. The case study selected for this study was Ometepe Island in Nicaragua, where the crater lake of an extinct volcano was considered a feasible upper reservoir of a pumped storage hydropower plant, reducing the investments associated with this component. The mathematical formulation considers energy storage losses and gains, and the Pareto efficient solutions of the multi-objective optimization model simultaneously increase reliability, reduce the cost of energy, and minimize curtailment energy. By employing time-series with an hourly resolution, the model allows assessing the impact of the interannual variability of renewable energy sources on the system's performance. As for the case study, the cost of energy obtained from the model results ranges between €0.047/kWh and €0.095/kWh, based on international reference values, and these values match the information available in the literature and other databases.

Design Implementation and Operation of an Education Laboratory-Scale Microgrid

To enable more wide-scale exploitation of renewable energy sources (RESs), distributed generations (DGs) as in microgrids have gained prominence recently. This study describes the design, modeling, implementation, and operation of a microgrid, in which a standalone hybrid power system has been installed for an education and research laboratory. The unstable nature of RESs results in power compatibility issues on DGs. Therefore, providing a decent power flow from renewables to loads is the scope of this paper. To satisfy defined load profiles and sustain the power with the desired level, the design and operation of power converters are a remarkable part of performing microgrids as well. For a robust microgrid structure, the presented control algorithm includes an energy management system (EMS) between renewables, batteries, and loads. Primarily, modeling of the system has been developed in MATLAB/Simulink environment. Additionally, case studies have been exemplified to further demonstrate the simulated system. Within this scope, certain load profiles not only have been fed but also power flow has been managed and analyzed to ensure effective and flexible operation with two different EMS cases. The real-time operation has been also provided to validate the system under various input and output conditions during a lab course.

Reliability Constrained Socio‐Economic Analysis of Renewable Generation Based Standalone Hybrid Power System with Storage for off‐grid Communities

Reliability Constrained Socio‐Economic Analysis of Renewable Generation Based Standalone Hybrid Power System with Storage for off‐grid Communities

Optimal sizing design of an isolated stand-alone hybrid wind-hydrogen system for a zero-energy house

This study examines the feasibility and optimal sizing design of a stand-alone wind/hydrogen hybrid power system for a house in Catalca, Istanbul, Turkey. The considered house is a remote house with no connection to the power grid lines. The designed system guarantees uninterrupted, reliable continuous power to the house at any time. The site location of Catalca is very suitable for wind energy, and the considered hybrid wind/electrolyzer/fuel-cell power system is a good alternative for supplying the energy need of the house. If the reliability of the power supply is crucial, then optimal sizing of the components, wind turbine, electrolyzer, storage tank, and the fuel-cell stack is critical. In this study, a stand-alone hybrid power system with a wind turbine, electrolyzer, storage tank, and fuel-cell stack that can supply the house continuously is sized using 10-minute averaged wind data of the site and consumption data of the house. As a usual practice in the wind market, for stand-alone houses, usually wind turbines with rated powers equal to almost three times the average power consumption is used. Our analysis showed that when an uninterrupted continuous power supply is a necessity, wind turbines with rated powers of at least ten times the average consumption should be used. Moreover, our analysis showed that such a study that accounts for calculations of all system components in small timeframes is essential to ensure uninterrupted continuous power supply. And the results show that the system is capable of providing uninterrupted power to the house all-year long.

A New Hybrid Controller for Standalone Photovoltaic Power System with Unbalanced Loads

Due to several problems such as global concern about environmental pollution, renewable energy has become an alternative source of energy. In situations such as small local loads far from the main grid, standalone hybrid power system (HPS) with inevitable unbalanced loading condition is preferred for the global grid. The four-leg inverter with a simple as well as well-performance control method is a good solution to support this condition. In this paper, with respect to the average and discretized model of the inverter, a new digital controller is proposed in the abc reference frame to control the load voltages. The proposed controller offers several advantages such as simplicity, fast dynamic response, no need for transformation among different reference frames, and full compatibility with digital implementation which makes it as an excellent option to be employed in such systems. In addition, a new hybrid controller is also proposed which not only has the advantages of the proposed digital controller but also shows superior performance under nonlinear loads without imposing a high computational burden. To verify the effectiveness of the two proposed controllers, several simulation and experimental tests under different scenarios on a 3 kW setup are performed.

Optimization to Limit the Effects of Underloaded Generator Sets in Stand-Alone Hybrid Ship Grids

For the safety of the supply, diesel generator (DG) sets are used in various stand-alone power systems using variable-speed generators. The stand-alone hybrid grid system presented in this article, with a wind generator and a diesel generator, but also the system of a ship’s network, serves as an example. To ensure the safety of the ship’s exploitation, the parallel operation of two stand-alone power supplies is required. In parallel operation with the required symmetrical active power load (regardless of the load size), the internal combustion engine of the DG set is often underloaded. This leads to deterioration of its technical properties and, consequently, to a negative impact on the environment. This article presents an analysis of the stand-alone hybrid power system of a ship’s grid consisting of a DG with a speed and voltage regulator and a shaft generator of variable speed—a permanent magnet synchronous generator (PMSG). The possibility of controlling the active and reactive power distribution between the DG and shaft generator (SG) was also studied. Control over the mechatronic SG–DG system limits the harmful influence of the DG on the environment and, most of all, improves the technical qualities of the engine of the DG system, which is often underloaded. Analytic studies of the system were performed, and simulation results of the mechatronic model are presented.

Design of Grid-tied Hybrid Diesel-Renewable Energy Systems Using Power Pinch Analysis

Diesel power systems have been widely applied for energy supply generation. This power scheme however requires periodical maintenance and contributes to the emissions of greenhouse gases. These challenges may be mitigated by integrating existing diesel station with renewable energy (RE) technologies into a hybrid system. Integration of diesel plants with RE systems has been mostly implemented using software and mathematical programming approaches, where the focus of the study is mainly on grid-independent hybrid system. Grid-connected hybrid systems have the potential to supply electricity at a lower cost in comparison to the standalone hybrid power systems. This work aims to design a system that integrates diesel plant with RE technologies into grid-tied hybrid system using insight-based Power Pinch Analysis (PoPA) method. The interactions between diesel generator, RE sources and the grid in meeting the load demands were considered in the methodology development. Various load sharing scenarios between the multiple generation sources were assessed to establish the optimal system operation. Economic assessment was performed to ensure the trade-off between the costs of generation sources and grid electricity cost can be maximized. Based on the demonstrated Illustrative Case Study, load sharing based on peak/off peak period contributes to the lowest net present cost of MYR 32,813,708, hence is deduced as the optimal on-grid hybrid diesel RE system.

Standalone hybrid power system using homer software optimal case sizing of ferraguig (North West of Algeria)

Standalone hybrid power system using homer software optimal case sizing of ferraguig (North West of Algeria)