Presence Of Renewable Sources Research Articles

Evaluating the role of prosumers in providing energy systems with flexibility products

AbstractIncreasing the penetration of renewables on the demand side causes operational challenges in distribution grids due to their variable and uncertain behaviour. These resources have increased distribution grid net load fluctuation during recent years, which needs to be covered by demand side flexibility (DSF). DSF should be quantified and measured by a suitable index to show the level of a system DSF in different situations. In this paper, the flexibility area index of distribution systems as a suitable metric for prosumers’ DSF evaluation, especially in the presence of renewable sources, is calculated. This index is defined first for one prosumer and then extended to a distribution system by a combination of prosumer indices. The mentioned index is decomposed into two components, one for ramp‐up (negative flexibility) and another for ramp‐down (positive flexibility). To calculate and manage prosumers’ flexibility, a novel flexibility‐oriented stochastic framework for prosumers is suggested. The amount of load shedding is under control by the risk‐management strategy in the proposed framework, which can facilitate distribution system operator operation. The results obtained from the implementation of the case study validate the major features of the proposed framework more efficiently.

A day‐ahead energy management strategy for electric vehicles in parking lots considering multi‐scenario simulations and hydrogen storage system

AbstractThis article investigated the charge and discharge management structure of electric vehicles (EVs) in intelligent parking lots (IPLs). It seems that with the expansion of renewable energy sources (RESs) as clean energy and investigation of the effects of EVs on the operation and planning of future distribution networks around the way EVs exchange energy with each other and the upstream network operator, RESs such as solar and wind sources, along with hydrogen storage are essential. Therefore, a new stochastic multi‐scenario approach for charge/discharge management of EVs parked in IPL was proposed, in which a newly developed model for the IPL with a hydrogen storage system (HSS) consisting of a fuel cell, an electrolyzer, and a hydrogen storage tank was presented. In the proposed model, the constraints of upstream network and power balance constraints, with the operating constraints related to the IPL, including EVs, renewable energy sources, and the hydrogen storage system, were formulated as the most important objectives of the optimization problem. The optimization algorithm, Competitive Swarm Optimizer (CSO), was formulated for implementation, and its results were compared with those of the PSO and GWO algorithms. The CSO must handle a variety of practical, large‐scale optimization problems. Based on the obtained results, the excess energy purchased from the upstream network or renewable sources was used as hydrogen storage for consumption during peak hours. As expected, the technical constraints and financial goals of the system were met, and the proposed system was evaluated on a 33‐bus network. As the expected benefits will be the most beneficial with the presence of renewable sources, the final profit will be reduced by taking into account uncertainty for charge/discharge management in EVs such as the uncertainty of electric load, market price, wind turbine, and photovoltaic cell sources. Nonetheless, the profit obtained from renewable resources is preferable to losses resulting from the uncertainty of the system, and according to expectation, the performance of the system for managing the optimal charging and discharging of EVs in the IPL will be acceptable with the maximum profit for the grid.

Analyzing flexibility options for microgrid management from economical operational and environmental perspectives

Power grids have undergone a massive transformation due to increasing number of renewable/non renewable distributed generators, storage technologies and electrical vehicles. This paper focuses on the flexible energy management of grid connected microgrid (MG) in order to analyze the effects of the flexibility options such as electric vehicle with demand response (EV-DR), battery storage system (BSS), hydrogen storage system (HSS) and dynamic line rating (DLR) in presence of renewable sources. In addition, microturbine (MT), fuel cell (FC), biomass (BIO), geothermal (GEO), and diesel engine (DIE) whose output is controllable are also considered as flexible sources. In this paper, optimum operation of grid-connected MG is modeled as a mixed-integer linear programming problem considering uncertainties of wind turbine (WT) and photovoltaic (PV) sources. A day-ahead forecasting of irradiance and wind speed are performed with Decision Tree Regression (DTR) and Long Short Term Memory (LSTM) algorithms for sensitive calculation of PV and WT output. The cost function merges operating costs including fuel, operation & maintains (O&M), depletion costs with emission cost of CO2, SO2, and NOx. Obtained numerical results show that total cost of the MG is reduced by 9.40% and emission cost is diminished by 5.59% with inclusion of all considered flexibility options. Further, load factor is improved from 0.7932 to 0.8236 with 100% flexibility condition for MG.

RETRACTED: Financial development, financial inclusion and natural resource management for sustainable development: Empirical evidence from Asia

A nation's economy relies heavily on the interplay of the nexus between the financial sector and the income generated by its natural resources. The key reasons for doing this research are the recent advancement and significant rise in the academic literature about the resource‐finance nexus. This study aims to assess the impact of financial development, financial inclusion and natural resources development on environmental sustainability in Asia's presence of renewable sources and foreign direct investment from 2000 to 2020. We used the Cross‐section dependency and second‐generation unit root tests to fix the data. Panel threshold model findings, the significant research model, reveal that green innovation significantly affects environmental sustainability and is an efficient method for lowering pollution levels. The strong correlation between financial growth and environmental sustainability further underscores the importance of financial development in resolving environmental concerns. Granger causality demonstrates the strong long‐run influence of financial growth and natural resources management on environmental sustainability in leading countries. The robustness of the GMM test ensures the validity of the research conclusions. This research is useful because it informs policymakers and other interested parties about the significance of green innovation and financial development in reducing environmental consequences while emphasizing the relevance of energy choices in achieving long‐term environmental goals.

Economic energy managementof networked flexi-renewable energy hubs according to uncertainty modeling by the unscented transformation method

The utilization of energy hubs (EHs) in the power system and simultaneous energy management of several energy networks is of high importance to increase energy efficiency. Therefore, this paper focuses on the energy management of grid-connected flexible energy hubs. Scheme includes electrical and heating networks, where renewables and storage devices are in connection using the hub as a coordinator. Problem minimizes the expected operating cost of the mentioned networks subject to networks optimal power flow model and the mathematical representation of flexible EHs. Uncertainties related to the amount of demand, price of electrical and heating energy, and renewable power have also been considered in the problem formulation. The unscented transformation method has been adopted to reduce the volume of the problem to obtain the optimal solution in low computation time, along with the precise modeling of flexibility and modeling of the aforementioned uncertainties. Modeling the flexibility of EHs in the presence of renewable sources, modeling bio-waste energy unit for the simultaneous generation of electric and heat energy, and modeling the various uncertainties of load using the unscented transformation are among the contributions of the paper. The obtained numerical results demonstrate the capability of the proposed scheme in improving the economic and operating status of electrical and heating networks, along with improving the flexibility of EHs in such a way that energy storages in renewable hubs can extract 100% flexibility conditions. In these conditions, the hubs are able to reduce energy costs, energy losses, voltage drop, and temperature by about 25%, 24%, 60%, and 59%, respectively, compared with the power flow studies of the networks under study. Also, based on sensitivity analysis results, the increase in load and energy price leads to an increase in the operating cost of the networks, while the increase in the size of renewable resources and storage devices reduces the networks’ energy cost.

Enhancement of the efficiency of solar energy cells by selecting suitable places based on the simulation of PV System

At present, the increasing demand for electrical energy and the presence of renewable sources in various forms in the world and, particularly in Iraq, such as solar energy and wind energy, have become the focus of researchers' attention. Huge efforts are focused on finding ways to use ecologically friendly energy to generate electricity and eliminate fossil fuels. In this study paper, we propose the use of a simulation program to discover the ideal location for a solar cell and the amount of time to be exposed to the sun's rays, so that a home powered by solar energy can be built. Also, through this program, the losses were calculated that accompany the conversion of light energy into electrical energy to find the necessary solutions to make the solar cell work with high efficiency.

Optimal design and operation of an islanded water-energy network including a combined electrodialysis-reverse osmosis desalination unit

This paper proposes an optimization framework to simultaneously optimize the saline and freshwater water sources as well as decentralized renewable and conventional energy sources, which consequently results in an economic and efficient water-energy system operation. The inextricable links between water and energy systems are taken into considerations, and a mixed integer nonlinear programming formulation is used to solve the proposed optimization model. A hybrid electrodialysis-reverse osmosis is integrated in the water distribution system and its electricity consumption is minimized. Also, the day-ahead economic dispatch problem of the energy system incorporates the random behavior of solar and wind generation units, along with charging and discharging modes of battery storage systems. The outcomes of the proposed models highlight: 1) integrating the hybrid desalination module in the water-energy system will reduce peak demands by more than 30% if the water and energy systems are solely supplied by saline water and renewable energy sources, respectively; 2) presence of an extra water storage tank also decreases peak demands by 13%. The impact of key elements of the combined system such as pumps’ speeds, water tank constraints, and presence of renewable sources on the output cost, generated energy, and hydraulic parameters is investigated through case studies.

Renewable energy regulation and structural breaks: An empirical analysis of Spanish electricity price volatility

Abstract International experience proves that electricity prices have undergone major changes in volatility since the entry of green technologies. The intermittency of renewable sources is one of the reasons for these changes, as it leads to higher volatility in periods of higher participation by renewables. We argue that the development of the regulatory system promoting renewable electricity also plays a crucial role. We raise a question that deserves attention: could an incentive scheme induce higher share of renewables and lower volatility simultaneously? In this paper, we conduct an empirical analysis with Spanish data. We analyze possible ensuing structural changes in Spanish electricity spot price volatility from January 2002 to December 2017. We identify two structural breaks linked to important measures related to renewable electricity: (i) the abolishment of the feed-in tariff scheme; and (ii) the establishment of a more market-oriented regulation based on investment and operating costs. We conclude that stable regulatory policies reduce volatility even though the presence of renewable sources is greater. Furthermore, market-based policy measures achieve lower volatility, encouraging good integration of intermittent renewable electricity.

Frequency control of an island microgrid using reset control method in the presence of renewable sources and parametric uncertainty

ABSTRACT In recent years, several powerful control methods have been proposed. One of these methods is the reset control, simple nonlinear control technique very effective for plants subjected to fundamental design limitations, and this paper suggests its implementation for secondary control of the frequency of an island microgrid. The studied microgrid includes various elements such as renewable energy sources and various factors such as the load changes, power fluctuations from renewable energy sources, dynamic disturbances as well as parametric uncertainties affecting the frequency of the grid and the complexity of its control. To overcome the above effects and stabilize the network frequency, this paper uses the reset control method to regulate the network operating frequency. Using the proposed controller, the behaviour of the network under parametric changes and different disturbances has been investigated and compared with conventional and optimized PID control methods. High speed frequency regulatory and low undershot/overshot are some of the advantages of the proposed method. The simulation results show the desired performance of the proposed control method in stabilizing the network frequency under different scenarios.

Demand-Side Management in Microgrids with the Presence of Renewable Sources in Vietnam

This paper proposes a general demand-side management strategy in microgrids with the presence of renewable sources. To apply proposed above strategy by electric price in Vietnam, it must be participated of photovoltaic and wind power generations and energy storage. An algorithm applied for this program is created by comparing amount of energy generating from generations and consumed by electric load. Amount of energy that must be bought from the grid or sells to it can be calculated by dispatching energy between hours that have the lowest electric price level and hours that have the medium and highest electric price levels. A case study that energy generating from generations is not equal energy consumed by load in hours having the medium and highest electric price levels is made more detailed in this paper. Algorithms to dispatch energy at any time to achieve the purpose of not buying electricity from the grid in above hours basing on electric price levels, efficiency of energy conversion, rated capacity of units and analysis of power flows in whole system. Results providing from algorithms are energy that must be bought from the grid or sell to the grid, instantaneous capacity of energy storage. Simulation results corresponding to this case study carried out in MATLAB 2018a present the meaning and feasibility of proposed contents.

Day ahead scheduling of generation and storage in a microgrid considering demand Side management

Abstract The problem of day-ahead scheduling of generation and storage facilities in a microgrid in the presence of Renewable sources with an objective to minimize the cost of power generation is considered in the article. The objective function is formulated considering a linear cost function for renewable generators and quadratic cost function for conventional generators. The uncertainty in available power from renewable generators and loads is modeled using a proven uncertainty model and two scenarios are drawn. Artificial Fish Swarm intelligence is used to solve the optimization part. The proposed algorithm is investigated on a numerical example with a cluster of renewable and conventional generators with different cost functions. The results obtained show that the proposed algorithm is able to utilize the cheapest sources to the extent of 100% and utilize the other generators in decreasing percentage as their cost of generation increases. The costliest source, which is grid power in the numerical example considered, is utilized only very sparingly. Apart from obtaining optimal solution for scheduling, the proposed algorithm is able to consolidate battery - microgrid power exchange and also implement load shedding when required.

Stochastic expansion planning of interconnected distribution networks with renewable sources considering uncertainties and power transfer capability

This study proposes a stochastic optimisation model for interconnected distribution network planning (IDNP) in the presence of renewable sources (RSs) considering power transfer capability after an N − 1 contingency. Two types of scenarios, feeder contingency, and substation transformer contingency, are formulated in the IDNP problem. Uncertainties of the RS output and load fluctuation are also integrated. The planning method provides planners with the decisions of feeder reformation, new tie lines, new feeders, substation expansion, new substations and new load allocation. The IDNP model is a chance-constrained mixed integer non-linear programming problem, which is solved by dynamic niche differential evolution algorithm. A case study carried out on a modified 104-bus distribution network demonstrates the effectiveness of those techniques. Compared with the traditional planning approach, the IDNP method could exploit asset utilisation by optimising existing networks efficiently as well as improve system economy and security simultaneously.

Design criteria for a power management system for microgrids with renewable sources

The paper describes the control functions that a power management system (PMS) needs for controlling a microgrid, with both conventional and renewable sources. According to the IEEE 1547.4, distributed resources island systems – or in brief “microgrids” – are active networks containing both loads and distributed generators, and may require a modification of their control logic if they are connected to a grid or not. A fast load or generator shedding actions may also be required to preserve system stability in case the microgrid switches from connected to islanded. Today, most industrial networks are designed to run also in islanded mode, while in public networks transmission system operators (TSO) generally do not allow islands. The presence of renewable sources that are partially not controllable requires the re-definition of the control logic compared with microgrids where only fully controllable generators are present. PMS of a microgrid has a double function:-to guarantee the stable operation of the system in presence of the unpredictable variations caused by renewable sources and loads,-to optimize the energy production of renewable and conventional sources.The logic described in the paper was implemented in a PMS that was tested with a software simulator prior to the installation in a real microgrid. The paper reports the results of tests.