Analytical Study of the Effects of Grid Resistance on Grid-Connected PV Systems: Modeling and Simulation

Author(s):  
S. F. Al-Gahtani ◽  
R. M. Nelms

Renewable energy systems have become common in power systems. Many problems associated with connecting a renewable energy system to utility network have arisen. In the traditional power calculation, the resistance of the line is ignored because of large the X/R ratio. However, the R/X ratio in the distribution network is greater than in transmission. Because of that, the line resistance should be considered in the power calculations. In this paper, the effect of the grid resistance on transfer of power is investigated by calculating the active power between a PV system and the grid where the grid resistance is included. Two models were developed to study the effects of the grid resistance. The sensitivity of real and reactive power to the grid impedance, the current performance and the phase angle for the maximum power were studied under variations of the grid resistance. The results from both models have been compared to emphasize that the transfer of power is really influenced by the resistance of the line impedance.

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 115
Author(s):  
Nasser Hosseinzadeh ◽  
Asma Aziz ◽  
Apel Mahmud ◽  
Ameen Gargoom ◽  
Mahbub Rabbani

The main purpose of developing microgrids (MGs) is to facilitate the integration of renewable energy sources (RESs) into the power grid. RESs are normally connected to the grid via power electronic inverters. As various types of RESs are increasingly being connected to the electrical power grid, power systems of the near future will have more inverter-based generators (IBGs) instead of synchronous machines. Since IBGs have significant differences in their characteristics compared to synchronous generators (SGs), particularly concerning their inertia and capability to provide reactive power, their impacts on the system dynamics are different compared to SGs. In particular, system stability analysis will require new approaches. As such, research is currently being conducted on the stability of power systems with the inclusion of IBGs. This review article is intended to be a preface to the Special Issue on Voltage Stability of Microgrids in Power Systems. It presents a comprehensive review of the literature on voltage stability of power systems with a relatively high percentage of IBGs in the generation mix of the system. As the research is developing rapidly in this field, it is understood that by the time that this article is published, and further in the future, there will be many more new developments in this area. Certainly, other articles in this special issue will highlight some other important aspects of the voltage stability of microgrids.


Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4150
Author(s):  
Lluís Monjo ◽  
Luis Sainz ◽  
Juan José Mesas ◽  
Joaquín Pedra

Photovoltaic (PV) power systems are increasingly being used as renewable power generation sources. Quasi-Z-source inverters (qZSI) are a recent, high-potential technology that can be used to integrate PV power systems into AC networks. Simultaneously, concerns regarding the stability of PV power systems are increasing. Converters reduce the damping of grid-connected converter systems, leading to instability. Several studies have analyzed the stability and dynamics of qZSI, although the characterization of qZSI-PV system dynamics in order to study transient interactions and stability has not yet been properly completed. This paper contributes a small-signal, state-space-averaged model of qZSI-PV systems in order to study these issues. The model is also applied to investigate the stability of PV power systems by analyzing the influence of system parameters. Moreover, solutions to mitigate the instabilities are proposed and the stability is verified using PSCAD time domain simulations.


Author(s):  
Mohammad Omar Abdullah ◽  
Voon Chun Yung ◽  
Audra Anak Jom ◽  
Alvin Yeo Wee ◽  
Martin Anyi ◽  
...  

The eBario project has won the eAsia Award and the Mondialogo Engineering Award in 2004 and 2005 respectively for it’s successful implementation of an Information and Telecommunications Technology Center (ICT) and solar renewable energy-incentive rural community project at the Bario Highland of Sarawak, East Malaysia, Borneo (http://www.unimas.my/ebario/). Although solar photovoltaic (PV) energy has been opted for power generation at the ICT Telecenter for the past five years, there is still a need to investigate the cost-effectiveness of the current energy setup as well as to conduct sustainability study taking into account factors such as system efficiency, weather, costs of fuel, operating costs, as well as to explore the feasibility of implementing alternative energy resources for the rural ICT Telecenter. Recent theoretical study conducted has shown that renewable combined power systems are more sustainable in terms of supplying electricity to the ICT Telecenter, and in a more cost-effective way compared to a standalone PV system which is subject to the cloud and the recent dense haze problems. For that purpose, two combined power systems are being put into consideration namely PV-Hydro and PV-Hydro-Fuel Cell, where the total simulated annualized cost for these two system configurations are US$10,847 and US$76,010 respectively as far as the present location is concerned. The PVHydro-Fuel Cell produces electrical energy at the amount of 3,577 kWh/yr while the annual energy consumption is 3,203 kWhr/yr. On the other hand, PV-Hydro produces 3,789 kWhr/yr of electricity annually load which consumes energy at 3,209 kWhr/yr. Results thus obtained has shown that the PVHydro scheme is expected to have advantages over the existing PV standalone system. Firstly, it is more cost-effective. Secondly, it provides the best outcomes for the local indigenous community and the natural highland environments both for now and the future. Thirdly, it also able to relate the continuity of both economic and social aspects of the local society as a whole. As the combined PV-Hydro system had been chosen, plus for completeness purposes, the present paper also discussed the custom design and construction of a small waterwheel breast-shot hydro-generator, suited to the local location and existing water energy resources. Energy saving design calculations and Sankey diagram showing the energy flows for the new combined system are also given herein. Finally, the energy system performance equations and the performance curves introduced in this study provide a new simple method of evaluating renewable energy systems.


2021 ◽  
Vol 7 (3) ◽  
pp. 30-33
Author(s):  
Sourabh Kedar ◽  
Mr. Santosh Singh Negi

Solar photovoltaic (PV) systems have mainly been used in the past decade. Inverter-powered photovoltaic grid topologies are widely used to meet electricity demand and to integrate forms of renewable energy into power grids. Meeting the growing demand for electricity is a major challenge today. This paper provides a detailed overview of the topological trend of inverters with connection to the photovoltaic grid, as well as the advantages, disadvantages and main characteristics of the individual inverters. For proper integration into a network, coordination between the supporting devices used for reactive power compensation and their optimal reactive power capacity for grid current stability is important.


Author(s):  
Ayong Hiendro ◽  
Ismail Yusuf ◽  
F. Trias Pontia Wigyarianto ◽  
Kho Hie Khwee ◽  
Junaidi Junaidi

<span lang="EN-US">This paper analyzes influences of renewable fraction on grid-connected photovoltaic (PV) for office building energy systems. The fraction of renewable energy has important contributions on sizing the grid-connected PV systems and selling and buying electricity, and hence reducing net present cost (NPC) and carbon dioxide (CO<sub>2</sub>) emission. An optimum result with the lowest total NPC for serving an office building is achieved by employing the renewable fraction of 58%, in which 58% of electricity is supplied from the PV and the remaining 42% of electricity is purchased from the grid. The results have shown that the optimum grid-connected PV system with an appropriate renewable fraction value could greatly reduce the total NPC and CO<sub>2</sub> emission.</span>


2021 ◽  
Author(s):  
Rachel Koh ◽  
Jordan Kern ◽  
AFM Kamal Chowdhury ◽  
Stefano Galelli

&lt;p&gt;Multi-sector modelling frameworks are fundamental platforms for exploring the complex interactions between the water and energy sectors. While acknowledging the pivotal role of hydropower within the energy system, it is essential to understand the feedback mechanisms between power and water systems to guide the design of hydropower operations and enhance water-energy management strategies. With this in mind, we developed a modelling framework hinged on a bidirectional coupling between water and power system models. We simulate the constraints imposed by water availability on grid operations as well as the feedback between the state of the energy and water systems. For example, the framework explicitly accounts for conditions of hydropower oversupply, during which part of the water could be stored in reservoirs or allocated to other sectors. The flexibility added to the system gives operators control over desired reservoirs, and allows the system to exploit the benefits warranted by a more efficient use of renewable energy. We evaluate the framework on a real-world case study based on the Cambodian grid, which relies on hydro, solar, and thermoelectric resources. In our analysis, we demonstrate that managing hydropower reservoirs with the feedback mechanism in mind allows us to improve system&amp;#8217;s performance&amp;#8212;evaluated in terms of power production costs and CO&lt;sub&gt;2&lt;/sub&gt; emissions. Overall, our work contributes a novel modelling tool for climate-water-energy nexus studies, working towards an optimal integration of hydropower and other renewable energy sources into power systems.&lt;/p&gt;


Energies ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 185 ◽  
Author(s):  
Amrita Raghoebarsing ◽  
Angèle Reinders

The aim of this paper is to give an overview of the energy sector and the current status of photovoltaic (PV) systems in Suriname and to investigate which role PV systems can play in this country’s future energy transition. At this moment, 64% of the power is available from diesel/heavy fuel oil (HFO) gensets while 36% is available from renewables namely hydroelectric power systems and PV systems. Suriname has renewable energy (RE) targets for 2017 and 2022 which already have been achieved by this 36%. However, the RE target of 2027 of 47% must be achieved yet. As there is abundant irradiance available, on an average 1792 kWh/m2/year and because several PV systems have already been successfully implemented, PV can play an important role in the energy transition of Suriname. In order to achieve the 2027 target with only PV systems, an additional 110 MWp of installed PV capacity will be required. Governmental and non-governmental institutes have planned PV projects. If these will be executed in the future than annually 0.8 TWh electricity will be produced by PV systems. In order to meet the electricity demand of 2027 fully, 2.2 TWh PV electricity will be required which implies that more PV systems must be implemented in Suriname besides the already scheduled ones.


2020 ◽  
Vol 170 ◽  
pp. 01015
Author(s):  
Avinash Kaldate ◽  
Amarsingh Kanase-Patil ◽  
Shashikant Lokhande

One downside to Green Energy is that it cannot be estimated. Therefore, determining the optimum planning and perfect working strategies for the resources to be included in the hybrid system is very important. HOMER software has been used in this research paper to solve the case study of the hybrid renewable energy system. Due to its extensive analytical capabilities and advanced prediction capabilities based on the sensitivity of variables, HOMER is one of the most used software for optimal planning purposes. A case study for the sizing of a renewable energy-based hybrid system is solved in this article, using the Hybrid Optimization of Multiple Energy Resources (HOMER) software. Photovoltaic panels (PV panels), wind turbines (WT), batteries, converters, electric charge and grid are used in case study. The results of the simulation are presented in graphical form and tabulated for better system visualization. The design of a system to supply 6.8 KWh/d whereas the peak is 1.04 KW electric loads has been performed using HOMER software. In order to allow the user to choose the most suitable option, a comparative analysis has made, showing the pros and cons of cases. Optimum construction conditions help to lower operating costs.


2013 ◽  
Vol 479-480 ◽  
pp. 570-574
Author(s):  
Cong Hui Huang ◽  
Chih Ming Hong ◽  
Yih Feng Su ◽  
Song Mao Lee ◽  
Chuan Sing Jhuang ◽  
...  

This paper presents Elman neural network for the dynamic control strategies of a hybrid power system that include wind/photovoltaic/diesel system. Wind and PV power are the primary power sources of the system to take full advantages of renewable energy, and the diesel-engine is used as a backup system. A simulation model for the hybrid energy system has been developed using MATLAB/Simulink. To achieve a fast and stable response for the real power control, the intelligent controller consists of a Radial Basis Function Network (RBFN) and an modified Elman Neural Network (ENN) for maximum power point tracking (MPPT). The pitch angle of wind turbine is controlled by ENN, and the PV system uses RBFN, where the output signal is used to control the DC / DC boost converters to achieve the MPPT.


2020 ◽  
Vol 5 (11) ◽  
pp. 1376-1382
Author(s):  
Zacchaeus A. Adetona ◽  
Joel Ogunyemi ◽  
Irmiya Bitrus

The perennial inadequate power supply problem in Nigeria, the worldwide call for green energy and the unavailability of grid electrical supply or difficulty in accessing it have created a need for the adoption of renewable energy such as solar PV systems. PV systems have a lifespan ranging from 10 to 25 years if well maintained but it has been observed that PV systems do not last up to their useful lifespan in Nigeria. A preliminary survey carried out showed that 71.2% of sample did not carry out any maintenance on their PV installations, 85.7% agreed that a lack of maintenance was responsible for their nonfunctional PV systems and 95% of the respondents agreed that there was a lack of maintenance on PV installations in Nigeria. A maintenance regime was developed for PV systems whereby a maintenance personnel is appointed to carry out routine or breakdown maintenance on solar panels, charge controller, battery, inverter, and cabling. The regime starts with turning off power coming from the solar panels. The maintenance of the solar panels follows; next is maintenance on all cable wiring and terminations. After all cable terminations have been checked, the battery maintenance follows. The charge controller is then checked for maintenance and subsequently, power from solar panels can be switched on to restore charging. Two protective installations were recommended in the maintenance regime namely the installation of earthing and DC circuit breakers to protect the solar system installation.


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