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• paper presents the development of these micro-sources i.e photo voltaic array, fuel cell stack along with their power electronic interfacing circuits viz. boost converter, PWM inverter in Matlab/Simulink and finally combining these models to form a Micro-Grid.
 
• paper presents the development of these micro-sources i.e photo voltaic array, fuel cell stack along with their power electronic interfacing circuits viz. boost converter, PWM inverter in Matlab/Simulink and finally combining these models to form a Micro-Grid.
  
'''Yunwei Li, D. M. Vilathgamuwa and Poh Chiang Loh
+
=='''Yunwei Li, D. M. Vilathgamuwa and Poh Chiang Loh
[http://ieeexplore.ieee.org/stamp/stamp.jsptp=&arnumber=1331480&isnumber=29405 "Design, analysis, and real-time testing of a controller for multibus microgrid system"] in IEEE Transactions on Power Electronics, vol. 19, no. 5, pp. 1195-1204, Sept. 2004. doi: 10.1109/TPEL.2004.833456 '''
+
[http://ieeexplore.ieee.org/stamp/stamp.jsptp=&arnumber=1331480&isnumber=29405 "Design, analysis, and real-time testing of a controller for multibus microgrid system"] in IEEE Transactions on Power Electronics, vol. 19, no. 5, pp. 1195-1204, Sept. 2004. doi: 10.1109/TPEL.2004.833456 '''==
  
 
• The controller proposed for use with each distributed generation (DG) system in the microgrid contains inner voltage and current loops for regulating the three-phase grid-interfacing inverter, and external power control loops for controlling real and reactive power flow and for facilitating power sharing between the paralleled DG systems when a utility fault occurs and the microgrid islands.
 
• The controller proposed for use with each distributed generation (DG) system in the microgrid contains inner voltage and current loops for regulating the three-phase grid-interfacing inverter, and external power control loops for controlling real and reactive power flow and for facilitating power sharing between the paralleled DG systems when a utility fault occurs and the microgrid islands.

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Contents

PV system + Micro-Grid Literature

Dinanath Prasad, Narendra Kumar, Rakhi Sharma "Modeling and Simulation of Microgrid Solar Photovoltaic System with Energy Storage" 2018 2nd IEEE International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES), doi: 10.1109/ICPEICES.2018.8897355

  • Presents integrated operations of PV system with energy storage device(battery).
  • Modeling and analysis of Microgrid components which includes PV array + use of MPPT.
  • Used PV array + enrgy storage unit, for maintenance of DC link voltage by using a control strategy.
  • Proposed Energy management system (EMS) algorithm to connet microgrid to utility grid.


Stefano Bracco, Federico Delfino, Federica Foiadelli, Michela Longo "On the integration of solar PV and storage batteries within a microgrid" 2019 IEEE International Conference on Environment and Electrical Engineering and 2019 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), doi: 10.1109/EEEIC.2019.8783861

  • Presents the role of energy storage system within Microgrid by presence of power plants which are fed by renewable sources mainly solar.
  • Presented an Energy Management System (EMS) based on a linear programming mathematical model, to manage the Microgrid daily and determine the optimal charging/discharging of storage unit in order to compensate the photovoltaic production and loads variability.
  • Microgrid case study (located N.Italy) was presented and the results were analysed for one month period.


Francisco González, Abraham Marquez, Jose I. Leon "Modelling of a microgrid for high integration of renewable sources" 2018 International Young Engineers Forum (YEF-ECE), doi: 10.1109/YEF-ECE.2018.8368942

  • Presents different models for a Microgrid.
  • Advanced power converters and robust communications are required for power conversions and to achieve high controllability and demand optimization.
  • Provides description of PV system and Energy storage control scheme.
  • Models being presented were developed using two techniques- switching model and average model.


Hussam Alatrash, Ruba A. Amarin, Cheung Lam "Enabling Large Scale PV Integration into the Grid" 2012 IEEE Green Technologies Conference, doi: 10.1109/GREEN.2012.6200939

  • Demonstrates the value of Generator Emulation Control (GEC), Volt-VAr and low voltage ride through (LVRT) technology.
  • Describes Microgrid technology in terms of reliable energy supply as well as microgrid feeders features which enables island operations during emergency.
  • Laboratory scale test bed was constructed, to demonstrate the effectiveness of Volt-VAr and LVRT functionality, in mitigating the PV intermittency.


James Hurtt, David Jhirad, Jessica Lewis "Solar Resource Model for Rural Microgrids in India" 2014 IEEE PES General Meeting | Conference & Exposition, doi: 10.1109/PESGM.2014.6939874

  • Development of Rural Microgrid in India by SPEED consortium.
  • SPEED-Smart Power for Environmentally-sound Economic Development.
  • Rural communities are evaluated for solar based microgrid deployment.
  • Solar resource model was developed to determine the optimal sized of solar array, impact of seasonal variations on production, and the need for energy storage to fill gaps of generation.
  • This Solar model aggregates raw data into averages for annual,monthly,daily and hourly irradiance.


S. Sheik Mohammed "Modeling and Simulation of Photovoltaic module using MATLAB/Simulink" International Journal Of Chemical and Environmental Engineering, October 2011, Volume 2, No.5

  • Design and building blocks of PV module based on the mathematical equations using MATLAB/Simulink.
  • Presents Mathematical model of PV cell and simulation of PV module.
  • Solarex MSX60/MSX64 PV modules are chosen for modeling.
  • Detailed discussion on Operation and Characteristics of PV/Solar Cells.


Xuan Liu, Bin Su "Solar Resource Model for Rural Microgrids in India" 2008 China International Conference on Electricity Distribution, doi: 10.1109/CICED.2008.5211651

  • Introduces to the concept of Microgrids, which addresses renewable energy technologies (RET) accompanied by distributed energy resources (DER), specially small scale renewable energy sources (RES) and combined heat and power (CHP).
  • Advantages of Microgrid.
  • Technical challenges associated with design and operation of microgrids.


Fabien Chidanand Robert, Sundararaman Gopalan "From Solar Microgrid Simulation to Field Deployment: Accuracy and Uncertainties" 2018 7th International Conference on Renewable Energy Research and Applications (ICRERA), doi: 10.1109/ICRERA.2018.8566777

  • Estimation of solar electricity generation by using HOMER Pro software and using NREL and NASA solar irradiance data sets.
  • Simulations results for the two test site were compared with the actual measurements.
  • Impacts of error in prediction were measured by performing microgrid design simulations.
  • Repercussions on hardware equipment, total cost, and temporal distribution of energy shortage were assessed.


Ahmad Al Otaibi, Saad Al Jandal "Solar photovoltaic power in the state of Kuwait" 2011 37th IEEE Photovoltaic Specialists Conference, doi: 10.1109/PVSC.2011.6186598

  • Assessment of local optimum tilt angle and power output of four photovoltaic modules is presented.
  • System Advisor Model (SAM) is used to perform computer simulations and analysis of functionality of each modules.
  • Hourly data was collected using solar radiation measurements at Kuwait.
  • Performance Evaluations using SAM for the solar electrical energy yield for different types of PV technology modules.


Yahya Z. Alharthi, Ahmad AlAhmed, Mohamed Ibliha, Ghulam M. Chaudhry, Mahbube K. Siddiki "Design, simulation and financial analysis of a fixed array commercial PV system in the city of Abu Dhabi-UAE" 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), doi: 10.1109/PVSC.2016.7750274

  • Preliminary study on designing 1.2MW-Commercial PV system.
  • System performance and financial analysis was presented using SAM and PVWatts for design,predict and analyze of commercial PV systems.
  • Simulation showed system performance in hourly,monthly and annually basis.
  • Based on operating costs, installations and system designs parameters that were specified as inputs,SAM and PVWatts software made the performance predictions and cost of energy estimates for this systems.


M. H. F Ahamed, U. D. S. D Dissanayake, H. M. P De Silva, H. R. C. G. P Kumara, N. W. A Lidula "Design and simulation of a DC Microgrid in PSCAD" 2016 IEEE International Conference on Power System Technology (POWERCON), doi: 10.1109/POWERCON.2016.7753856

  • DC Microgrid system designed for telecommunication power supply system and three possible modes of operation are discussed.
  • Solar characteristics are verified using manufacture specification.
  • A proper Energy Management and Control is proposed for the reliable operation of the DC Microgrid even under various disturbances.
  • Major concern is to maintain DC bus voltage at desired value and to protect the battery.
  • Proposed control algorithm ensures required continuous operation for a telecommunication system at a loss of grid undef intermittency of solar PV.


Ganesh Baliram Ingale, Subhransu Padhee, Umesh C. Pati "Design of stand alone PV system for DC-micro grid" 2016 International Conference on Energy Efficient Technologies for Sustainability (ICEETS), doi: 10.1109/ICEETS.2016.7583852

  • Modeling of Photovoltaic panel, designing of maximum power point tracking (MPPT) control algorithm for a standalone PV based distributed generation (DG) system is presented.
  • Classical MPPT (Perturb and Observe MPPT) is used to track the maximum power point of the system.
  • Sun Power SPR 305 WHT PV array and module are considered here and the simulation verifies the module characteristics and array characteristics.
  • The output voltage of PV panel varies with varying solar irradiation and ambient temperature.
  • Detailed mathematical model of PV cell has been carried out and the effect of solar irradiance and change of ambient temperature has been investigated.


Salahudin Iqbal Sidiki, Ahmad AlAhmed, Yahya Alharthi, Ghulam M. Chaudhry, Mahbube K. Siddiki "Design, simulation and financial analysis of stand-alone photovoltaic system at university of missouri-kansas city, Missouri, USA" 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), doi: 10.1109/PVSC.2016.7750273

  • Focus on design, performance and financial analysis of stand-alone photovoltaic (PV) system to meet daily light energy demand at Missouri-Kansas City.
  • To simplify design procedure in terms of reliability and cost, computer based tools-SAM and PVWatts were utilized for optimization and design.
  • System performance was simulated and financial analysis was carried out for a combination of PV array, battery storage, inverter and load of this system.
  • One of the significant step in designing PV system is to select proper location for installation as well as selecting descent system component parameters.
  • Based on the requirement of solar PV modules, inverter, battery storage and available solar radiation in the city, system performance criteria was optimized and improved.


Gauranshi Saxena, Lata Gidwani "Estimation of Energy Production of Grid Connected Rooftop Solar Photovoltaic System at Nagar Nigam Kota, Rajasthan" 2018 3rd International Innovative Applications of Computational Intelligence on Power, Energy and Controls with their Impact on Humanity (CIPECH), doi: 10.1109/CIPECH.2018.8724134

  • It discusses about the guidelines and technical specifications of various components of grid connected rooftop photovoltaic systems that are specified by Rajasthan for projects to be implemented there.
  • Feasibility of 100-KW grid connected rooftop PV power plant is analyzed.
  • Energy production estimations are calculated using RETScreen Expert and PVWatts software using solar radiation data files of that region,that were available with two softwares.
  • Using the prevailing tariff of electricity for government educational institutions, an estimate of annual cost savings is calculated.
  • Discussed about net metering circuit arrangements and energy production estimation for that region.


Mayuresh K. Dave "Modeling of PV arrays based on datasheet" 2016 IEEE 1st International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES), doi: 10.1109/ICPEICES.2016.7853617

  • A new method of PV cell modelling is proposed here.
  • Main objective is to model the PV cell with help of PV parameters and find the optimum I-V curve of the PV array.
  • Effect of seris and parallel resistors are taken into consideration during designing this model.
  • For every P-V curve, there is analogous I-V curve, by fitting mathematical data with the experimental data.


Dr. Rajashekar P. Mandi "Grid interactive Rooftop Solar PV Power Plant for Educational Institute " 2017 International Conference On Smart Technologies For Smart Nation (SmartTechCon), doi: 10.1109/SmartTechCon.2017.8358609

  • To implement solar power plant using grid interactive system.
  • Power during non solar hours is implemented from grid.
  • Excess energy during solar hours is pumped to grid.

Grid Integration Literature

K. A. Nigim and W. Lee, "Micro Grid Integration Opportunities and Challenges" 2007 IEEE Power Engineering Society General Meeting, Tampa, FL, 2007, pp. 1-6. doi: 10.1109/PES.2007.385669

1. Presents the opportunities and challenge facing the integration of microgrid with exiting utilities and concludes with the required steps needed to minimize the challenging factor

2. Energy management system – dispatches heat and power according to the demand and fuel availability at all times through coordination among the mix of the generating units.

3. Opportunities: - • To reduce dependency on imported fuel sources and to help in regulating prime fuel market competition.

• To enable the use of renewable energy sources

• To help rural Electrification

• To defer the constructing or extension if transmission lines

• To Push forward the virtual power management concept that utilizes local resources nationally

4. Challenges.

• Technical Challenges: - Issues such as safety, islanding, restoration from scheduled and unscheduled shut downs protection coordination, capacity and reserves Management.

• Non-technical Challenges: - issues such as pricing, incentive, decision priory, risk responsibility and insurance for new technologies adaption and interconnection standards.

"V. S. Tejwani, B. N. Suthar and D. A. Prajapati, "Integration of microgrid with utility grid for sharing real and reactive power" 2015 International Conference on Computer, Communication and Control (IC4), Indore, 2015, pp. 1-5. doi: 10.1109/IC4.2015.7375592"

1. Microgrid: - Distributed generation-based grid that contain both generations as well loads.

2. For smooth operation – necessary to maintain voltage and frequency of microgrid

3. This paper presents: - power exchange between Microgrid and utility grid at different loading condition.

4. Power Controller compares the reference and actual values of real and reactive power derived from grid and generates reference value for direct and quadrature axis component current.

5. The voltage sources inverter controls the flow of real and reactive power between the microgrid and utility grid.

6. The flow of real and reactive power from the Microgrid to the utility grid is determined by vector relation between inverter output voltage and utility grid voltage along with line reactance.

7. Active Power is mainly depends upon power angle and reactive power is mainly depends upon inverter output.

P. V. Joshi and S. S. Dhamal, "Study of different converter topologies for interconnecting microgrid with utility grid" 2015 International Conference on Control, Instrumentation, Communication and Computational Technologies (ICCICCT), Kumaracoil, 2015, pp. 731-734. doi: 10.1109/ICCICCT.2015.7475376

• Power Electronics converter play vital role in renewable energy systems and microgrids

• Grid Connected mode: -

1. The power fed into utility can be managed by either controlling of current injected or by power angle control.

2. For synchronizing converter output voltage or current, phase looked loop (PLL) control or grid voltage zero crossing detection can be implemented.

• Islanded mode: -

1. Microgrid is operated in this mode when utility is disconnected because of appearance of fault in utility

2. Microgrid converter has keep frequency and voltage with microgrid constant.

3. Several methods for parallel: - Frequency and voltage drop method and Master slave

• Battery charging mode: -

1. Due to intermittency of renewable generation sources and large time constraint, storage system should be present to manage disturbances and fast load changes.

2. Interconnection of microgrids with utility will surely help in reducing supply demand shortfall and customer participation in deregulated electrical sector.

N. P. Choudhary, K. S. Singne, P. G. Shewane and R. C. Ujawane, "Attainment of stability in microgrid and utility grid" 2015 International Conference on Industrial Instrumentation and Control (ICIC), Pune, 2015, pp. 285-288. doi: 10.1109/IIC.2015.7150754

• Stability of microgrid as well as in utility grid will be achieved by maintaining voltage and frequency of both the grid.

• For the achievement of stability, back to back converter is used. Vector control method is the method of controlling of HVDC Back to Back Converter is used.

• When the load shared in between microgrid and utility grid and vice versa, stability will be maintained because of accurate performance of control strategy.

• Power System Stability can be in utility grid and microgrid is achieved by controlling two independent quantities the frequency and fundamental voltage magnitude.

• A microgrid is interfaced to main power system by a fast semiconductor switch called the static switch (IGBT).

J. Hofer, B. Svetozarevic and A. Schlueter, "Hybrid AC/DC building microgrid for solar PV and battery storage integration" 2017 IEEE Second International Conference on DC Microgrids (ICDCM), Nuremburg, 2017, pp. 188-191. doi: 10.1109/ICDCM.2017.8001042

• Hybrid ac/dc microgrids combine advantages of both ac and dc systems and may facilitate the integration process of dc power technologies into existing ac systems.

• The performance of a hybrid building microgrid coupling on-site PV generation with ac and dc loads of a residential building is investigated in simulation.

• To integrate these technologies into existing ac power systems, complicated dc/ac inverters and controllers are required to synchronize with ac systems and to provide high-quality ac currents without harmonics.

• Challenges are related to lack of standardized equipment (dc network components are missing; end use appliances are lacking dc connectivity) and little industrial experience.

• The benefits of hybrid microgrids may be even larger for commercial and office buildings with integrated PV, due to a higher share of dc internal loads and increased self-consumption of PV electricity. PV and battery size are important parameters for the evaluation of hybrid microgrid performance.

• Dc networks are most efficient for buildings with a high degree of autarky enabled by a high share of dc renewable sources.

P. Wu, W. Huang, N. Tai, J. Xie and B. Lv, "An advanced architecture of multiple microgrids interfacing with UCC" 2017 IEEE Power & Energy Society General Meeting, Chicago, IL, 2017, pp. 1-5. doi: 10.1109/PESGM.2017.8274468

• Instead of the conventional point of common coupling (PCC), unit of common coupling (UCC), which consists of both AC and DC connection, is utilized in each microgrid, enabling multiple connection modes among microgrids and the utility grid.

• The UCC takes advantages of the utility grid to support the operation of multiple microgrids and the salient control features of modular multi-level converter (MMC) to optimize power-sharing.

• Characteristics of modular multilevel converter (MMC), unit of common coupling (UCC) is utilized in the micro grid instead of the conventional point of common coupling (PCC), thus enabling both AC connection between microgrids and the utility grid and DC connection among multiple microgrids.

• The UCC is preferred near the stable energy storage devices in the micro grid, providing AC and DC connection at the same time. The AC connection is solely used to connect microgrids and the utility grid through AC lines.

• The DC connection is used particularly for the interconnection among multiple microgrids through MMCs

• Connection Modes: - AC modes, DC Mode and Hybrid Mode.

• Control Modes: - Grid Connected Operation, Islanded operation and Abnormal operation.

M. A. Al Faruque and F.Ahourai,"GridMat: Matlab toolbox for GridLAB-D to analyze grid impact and validate residential microgrid level energy management algorithms" ISGT 2014, Washington, DC, 2014, pp. 1-5. doi: 10.1109/ISGT.2014.6816479

• Residential microgrid has the capability to participate in the distribution grid as a very flexible and dynamic component for demand side energy management (energy efficiency, peak-load reduction, and demand response)

• GridLAB-D is the most promising tool for power system modeling of a microgrid.

• It is limited in supporting advanced control algorithm development with debugging support and does not provide a user-friendly interface for modeling the structural and behavioral aspects of a residential microgrid.

• Matlab toolbox (GridMat) to integrate the capabilities of domain-specific modeling & simulation tools from power system (GridLAB-D) and control (Matlab).

• The capability of GridMat is to have different levels of energy management controllers (including direct load control) for a residential microgrid using this tool to reduce and shift peak load according to Time-Of-Use (TOU) electricity rate.

A. A. Radwan and Y. A. I. Mohamed, "Analysis and Active-Impedance-Based Stabilization of Voltage-Source-Rectifier Loads in Grid-Connected and Isolated Microgrid Applications" in IEEE Transactions on Sustainable Energy, vol. 4, no. 3, pp. 563-576, July 2013. doi: 10.1109/TSTE.2012.2227981

• The stability analysis and active-impedance-based stabilization of pulsewidth modulated voltage-source rectifier (VSR) loads in grid-connected and isolated voltage-source inverter (VSI)-based microgrid systems.

• Detailed and coupled admittance-based models of the VSR-interfaced load and the source side are obtained in the rotating reference frame by considering all control loops and phase-locked loop dynamics.

• The generalized Nyquist stability criterion, it is shown that a VSR-interfaced load can negatively interact with the source-side dynamics resulting in unstable voltage response at the point of interconnection.

• Active-impedance-based compensators are implemented in the control structure of the VSR-interfaced load to satisfy the generalized Nyquist stability criterion and provide seamless integration of VSRs into both grid-connected and isolated VSI-based ac systems.

R. Majumder, A. Ghosh, G. Ledwich and F. Zare,"Power Management and Power Flow Control With Back-to-Back Converters in a Utility Connected Microgrid" in IEEE Transactions on Power Systems, vol. 25, no. 2, pp. 821-834, May 2010. doi: 10.1109/TPWRS.2009.2034666

• power flow control between utility and microgrid through back-to-back converters, which facilitates desired real and reactive power flow between utility and microgrid.

• Mode-1 is specified amount of real and reactive power are shared between the utility and the microgrid through the back-to-back converters.

• Mode-2 is invoked when the power that can be supplied by the distributed generators (DGs) in the microgrid reaches its maximum limit.

• Proper relay-breaker operation coordination is proposed during fault along with the blocking of the back-to-back converters for seamless resynchronization.

A. Ruiz-Alvarez, A. Colet-Subirachs, F. Alvarez-Cuevas Figuerola, O. Gomis-Bellmunt and A. Sudria-Andreu,"Operation of a Utility Connected Microgrid Using an IEC 61850-Based Multi-Level Management System" in IEEE Transactions on Smart Grid, vol. 3, no. 2, pp. 858-865, June 2012. doi: 10.1109/TSG.2012.2187222

• Management system for a utility connected low-voltage microgrid composed of three nodes: a wind turbine, a battery and a variable load.

• Each unit is composed of two identical voltage sources in back-to-back configuration.

• The microgrid is managed by a three-layered hierarchical automation system: the RMU layer, the iNode layer and the iSocket layer.

• It has been developed an active and reactive power control that can be used for both management modes.

• IEC 61850 it has been used MMS-EASE Lite solution from SISCO

Ritwik Majumder, Manjula Dewadasa, Arindam Ghosh, Gerard Ledwich, Firuz Zare, “Control and protection of a microgrid connected to utility through back-to-back converters” Electric Power Systems Research, Volume 81, Issue 7, 2011

• control and protection of a microgrid that is connected to utility through back-to-back converters.

• The back-to-back converter connection facilitates bidirectional power flow between the utility and the microgrid. These converters can operate in two different modes–one in which a fixed amount of power is drawn from the utility and the other in which the microgrid power shortfall is supplied by the utility.

• protection and control schemes are able to ensure reliable operation of the microgrid.

A. Colet-Subirachs, A. Ruiz-Alvarez, O. Gomis-Bellmunt, F. Alvarez-Cuevas-Figuerola and A. Sudria-Andreu, "Centralized and Distributed Active and Reactive Power Control of a Utility Connected Microgrid Using IEC61850" in IEEE Systems Journal, vol. 6, no. 1, pp. 58-67, March 2012.

• control algorithm of a utility connected microgrid, based on independent control of active and reactive power and operating in centralized and distributed operation mode.

• units of microgrid interfaced with the microgrid through a voltage source converter and are controlled by the nodes of the communication system by means of IEC 61850.

• Microgrid is a concept that incorporates distributed energy resources (DER), including distributed generation and distributed storage.

• Static and dynamic analyses have been conducted. In both cases, the analysis is focused on active power. Reactive power would be shared proportionally by all the involved units.

Chowdhury, Rajdeep, and Tilok Boruah. "Design of a micro-grid system in MATLAB/Simulink." International journal of innovative research in science Engineering and Technology 4.7 (2015): 5262-5269.

• Micro-Grid(MG) is basically a low voltage (LV) or medium voltage (MV) distribution network which consists of a cluster of micro-sources such as photo-voltaic array, fuel cell, wind turbine etc. called distributed generators (DG’s); energy storage systems and loads; operating as a single controllable system, able to operate in both grid-connected and islanded mode.

• paper presents the development of these micro-sources i.e photo voltaic array, fuel cell stack along with their power electronic interfacing circuits viz. boost converter, PWM inverter in Matlab/Simulink and finally combining these models to form a Micro-Grid.

==Yunwei Li, D. M. Vilathgamuwa and Poh Chiang Loh "Design, analysis, and real-time testing of a controller for multibus microgrid system" in IEEE Transactions on Power Electronics, vol. 19, no. 5, pp. 1195-1204, Sept. 2004. doi: 10.1109/TPEL.2004.833456 ==

• The controller proposed for use with each distributed generation (DG) system in the microgrid contains inner voltage and current loops for regulating the three-phase grid-interfacing inverter, and external power control loops for controlling real and reactive power flow and for facilitating power sharing between the paralleled DG systems when a utility fault occurs and the microgrid islands.

• The controller also incorporates synchronization algorithms for ensuring smooth and safe reconnection of the micro and utility grids when the fault is cleared.

• With the implementation, the multibus microgrid system can switch between islanding and grid-connected modes without disrupting the critical loads connected to it.

E. Sortomme, G. J. Mapes, B. A. Foster and S. S. Venkata,"Fault analysis and protection of a microgrid"2008 40th North American Power Symposium, Calgary, AB, 2008, pp. 1-6. doi: 10.1109/NAPS.2008.5307360

• Fault currents are analyzed on a larger system of distribution network

• Objective -> how the protection will need to be changed to facilitate microgrid operation with the inclusion of DG sources and islanding capabilities.

• To protect the microgrid is to use digital relays with breakers at each line· bus connection so each line will have a breaker and digital relay at each end.

Solar Powered Schools Literature

F. Calise, "Thermoeconomic analysis and optimization of high efficiency solar heating and cooling systems for different Italian school buildings and climates" Energy and Buildings, 42(7), 992-1003, 2010.

  • Search: Google Scholar for "solar powered school"
  • economic profitability of system dependent upon public funding policies (ex: feed-in tariff)
  • system contributes to energy savings, emissions reductions and growth of use of renewable energy sources
  • incentive policies and demonstration projects needed to actualize this type of system at large scale
  • energy efficiency is a problem for school buildings because of enormous energy consumption rates

C. Filippin, "Thermal response of solar and conventional school buildings to design- and human-driven factors" Renewable Energy, 30(2), 353-376, 2005.

  • Search: Google Scholar for "solar school"
  • energy makes up a high percentage of costs for schools
  • Green School Project & Energy Smart Schools (U.S.) are initiatives aimed at improving the energetic and environmental efficiency of school buildings
  • LEED- Leadership in Energy & Environmental Design

Zhao et al., "The green school project: A means of speeding up sustainable development?" Geoforum, 65, 310-313, 2015.

  • Search: Google Scholar for "green school project"
  • schools are unique and special communities- have capacity to spread awareness of low carbon concepts and issues related to energy
  • Green School Project objective is to generate more students with sustainable consciousness, contribute to greater awareness of sustainable development and reduce carbon emissions
  • dependence on fossil fuels is driving energy shortage- global reserves are limited and fast depleting (less than 200 years to depletion)
  • schools are the potential breeding grounds of innovative ideas and trends
  • popularize sustainable development by providing students with environmental protection/energy conservation context
  • Green Schools conserve resources and enhance environmental quality by demonstrating/educating sustainability

Yilmaz et al., "Energy supply in a green school via a photovoltaic-thermal power system" Renewable and Sustainable Energy Reviews, 57, 713-720, 2016.

  • Search: Google Scholar for "green school and energy"
  • economic, technical and environmental feasibility study of grid-connected PV for a school
  • results show a school in similar climatic conditions to Kahramanmaras, Turkey can meet entire energy needs with renewable energy sources so long as optimal planning is employed
  • cost and performance of energy systems depends on human factors and design components selected
  • on-site renewable energy systems and technology are developing fast and are becoming more diversified
  • increase energy efficiency, lower costs and emissions simultaneously
  • "school's energy needs are met in an optimal manner with solar energy"

Jimenez, A. and Lawland, T., "Renewable Energy for Rural Schools" National Renewable Energy Laboratory, 2000.

  • Search: Google Scholar for "green school and energy"
  • integration of renewable energy resources into school buildings needs to be supported by a policy framework
  • RE power systems are commonly misconceived as unaffordable- initial cost evaluations often discourage RE development
  • excess energy supply can generate income to support operation and local community

Hau et al., "Analyzing the Impact of Renewable Energy Incentives and Parameter Uncertainties on Financial Feasibility of a Campus Microgrid" Energies, 11(9), 2018.

  • Search: Proquest for "school solar microgrid"
  • microgrids have environmental and technical advantages
  • high capital costs are a barrier to microgrid integration
  • analysis tool= Microgrid Decision Support Tool which aids decision making when it comes to microgrid project investment (OSS)
  • incentives, such as renewable energy incentive programs, have large influence over the financial feasibility and optimal design of a microgrid
  • shifting from centralized grid system to independent/decentralized system (microgrid) is gaining momentum
  • direct advantages of microgrids include: high penetration of RE resources, improved energy security/reliability, reductions in GHG emissions/fuel consumption and power system operating costs (LCOE)
  • when designing a microgrid system, imperative to perform a techno-economic analysis- determines feasibility
  • renewable energy tax credits and tax deductions provide huge potential benefits (net metering, investment tax credits, exemptions/incentives, etc.)
  • investment based incentives proved to have strongest impact- they decease high installation costs which has been the primary challenge of adopting RE systems

Fowlie et al., "Solar Microgrids and Remote Energy Access: How Weak Incentives Can Undermine Smart Technology" Economics of Energy & Environmental Policy, 8(1), 2019.

  • Search: Proquest for "school solar microgrid"
  • microgrid can be integrated to national grid if and when it wants to
  • households in this study were unwilling to pay for microgrid connection if a subsidized grid connection exists
  • community engagement is critical- projects fails unless they start from within
  • supporting commercial loads generates income
  • understand and accommodate political context of the environment in which it will operate

Santos et al., "Framework for Microgrid Design Using Social, Economic, and Technical Analysis" Energies, 11(10), 2018.

  • Search: Proquest for "school microgrid"
  • solutions to local energy systems=microgrids!
  • local characteristics such as social, political, legal and regulatory assert immense influence over project success/performance/feasibility
  • relevant stakeholders are provided numerous benefits: economic, environmental and technical- see figure 1 for microgrid benefits
  • consumers could potentially derive cheaper energy from microgrid than from main grid
  • reduced load on distribution grids during peak time (peak load shaving) and system stability
  • social benefits= increased public awareness, creation of job/research opportunities, energy saving incentives
  • decreased reliance on fossil fuel=increased resilience
  • design must consider household benefits, impact on local resources, management, utility regulation

Husein, M., and Chung, I., "Optimal design and financial feasibility of a university campus microgrid considering renewable energy incentives" Applied Energy, 225, 273-289, 2018.

  • Search: Proquest for "school microgrid"
  • renewable energy penetration and financial feasibility/viability of campus microgrid positively influenced by renewable energy investment-based incentives, tax benefits and grid ancillary services
  • created economic model using Microgrid Decision Support Tool (MDSTool) to determine optimal sizing and calculate system cash flows
  • microgrid benefits= emissions reductions, energy security and resiliency, energy/economic savings
  • industry is in need of an ideal business model for microgrids. Imperative to harness all the benefits associated with this investment in order to be more effective
  • benefits of microgrid investment= net metering, feed-in tariff, renewable energy incentives and grants, emission reduction credits, tax credits
  • claims minimal research has been done to understand how RE incentives and tax benefits effect microgrid planning
  • consider the tax status of the investor
  • conclusion: financial attractiveness of microgrids is dependent on incentives

Hanna et al., "Evaluating business models for microgrids: Interactions of technology and policy" Energy Policy, 103, 47-61, 2017.

  • Search: Proquest for "school microgrid"
  • most advocacy regarding decentralization emphasizes the potential for the deployment of renewable energy
  • customer energy costs can be reduced through decentralization (microgrids)
  • 3 primary factors driving growth in microgrid/decentralization= falling prices of PV and electric storage, rising costs of grid-service electricity, policy aimed at reducing emissions and promoting autonomous energy production
  • barriers to microgrid deployment= interconnection fees, prohibition of self-generated networks in some places
  • there are myriad public benefits of microgrids but the challenge is to get potential investors to see the private benefits
  • strategic to exploit a business model for investors to save money by shifting to microgrid service instead of standard grid
  • compared against macro grid utility service, microgrid can be cost-effective
  • policy makers can guide deployment of microgrids by structuring grid operations to be of widespread distributed microgrids
  • interconnection tariffs and the price of carbon are under direct jurisdiction of policy makers

Domenech et al., "A community electrification project: Combination of microgrids and household systems fed by wind, PV or micro-hydro energies according to micro-scale resource evaluation and social constraints" Energy for Sustainable Development, 23, 275-285, 2014.

  • Search: Proquest for "school microgrid"
  • in rural communities, it can be ideal to use renewable energies to power a decentralized electrification system
  • microgrids divert external dependence and promote the use of local resources (enhances long-term sustainability)
  • authors recommend hybrid systems as they bolster security of energy supply
  • standardized designs or solutions are often inappropriate and lack sensitivity to nuances/context of a particular community/location
  • decision making processes should include the local community in a participatory and equitable way
  • ask: what are the social characteristics of the populations involved?

El-Leathey et al., "Technical Economic Analysis of a Small-Scale Microgrid for a Specific Location" Electrotehnică, Electronică, Automatică, 63, 2015.

  • Search: Proquest for "school microgrid"
  • return on investments for microgrid projects vary- depending on the size of the project, the type of technology, location, infrastructure access, more..
  • power quality and price of those being supplied by microgrid must be at least equal to that of the public grid
  • reduction of the share of electricity being supplied by the public grid leads to profitable investment
  • study determined that microgrid is most effective/profitable if remains interconnected with the public grid, enables power injection as well as supplies users internal to the microgrid system

Prehoda et al., "U.S. strategic solar photovoltaic-powered microgrid deployment for enhanced national security" Renewable and Sustainable Energy Reviews, 78, 167-175, 2017.

  • grid resiliency and protection from threats is enhanced by using distributed generation as well as microgrids
  • the complex network that is the U.S. electrical grid is vulnerable to cascading failures
  • microgrids do not require redesign of existing main grid
  • distributed generation through a microgrid system enables high performance and minimized risk of grid failure
  • adopting solar PV distributed generation (microgrid) has become far more affordable in the past decade due to large-scale manufacturing, technical advancements and a significant learning curve
  • microgrid can simultaneously maintain energy independence and generate surplus of energy to supply surrounding community

Prehoda et al., "Putting Research to Action: Integrating Collaborative Governance and Community-Engaged Research for Community Solar" Social Sciences, 8(1), 2019.

  • paper investigates the costs, benefits and local contexts of community solar
  • community solar is defined by a central solar electricity system that distributes generated energy among those involved
  • a proactive approach to energy governance and increased use of renewable energy
  • it is critical to involve community members in energy transitions as this type of long-term structural change has large impact on all
  • community-engaged solar projects generate a multitude of benefits including: retaining monetary gains from energy savings within the community; a system design that does not lend itself to opposition; incorporation of community interests; stimulate bonds and cohesive relationships among community members; increased consciousness surrounding energy problems and solutions
  • energy independence created by community solar projects allows ownership and control of energy generation to be established by those involved
  • local access, ownership and increased affordability
  • important to be aware that community energy projects are naturally political and are constrained by the policy context in which they operate
  • In Michigan, the laws are organized in such a way that leaves community solar development to the discretion of the utility rather than the stakeholders themselves
  • Michigan community solar initiatives are only possible if partnered with a utility who has authority to install panels, sell power, etc.
  • inclusivity of those who are impacted by such projects is necessary for successful collaborative governance

Prehoda et al., "Policies to overcome barriers for renewable energy distributed generation: A Case study of utility structure and regulatory regimes in Michigan" Energies, 12(4), 2019.

  • political power of Michigan investor-owned utilities acts in financial interest of themselves
  • Michigan current utility structure does not cater to best interest of Michigan consumers
  • centralized, fossil-fuel based energy production is perpetuated by Michigan utilities who strategically misinterpret policy to bar the advancement of distributed/renewable generation
  • current regulatory regime must be challenged if we are to maximize societal and consumer benefits
  • benefits of distributed generation (generating electricity at or near the intended user)= increased reliability of energy, minimized transmission losses, affordable and locally controlled energy system= (energy justice!)
  • 3 different utility structures of Michigan= municipally owned (public); cooperative electric associations (public); investor owned utilities (private=for profit)
  • IOU's cater to their shareholders before their customers
  • Michigan IOU's have interpreted and implemented policy in a manipulative way that has successfully deterred/made unattractive the development of distributed and renewable energy generation
  • Michigan's net metering cap restricts net metering capacity at 1% which severely limits the growth of distributed generation

Wouters, C., "Towards a regulatory framework for microgrids—The Singapore experience" Sustainable Cities and Society, 15, 22-32, 2015.

  • microgrid can complement a centralized system and accommodate needs of growing society
  • climate change, growing energy demand and population pose an obstacle for the current energy system
  • non renewable energy resources constrict the growth of the energy supply system and provides grounds to explore and employ renewable energy swiftly
  • the technical and economic aspects of microgrids are well developed but there is a lack of regulatory/policy understanding
  • microgrids should be designed to cater to local needs and a specific location- no standard model or one size fits all
  • diversified energy resources=energy security!
  • generating energy at or near the end-consumer increases reliability and flexibility
  • characteristics of a locally controlled microgrid= generation unit (sources), energy loads (sinks), and energy storage units
  • policies and regulations regarding interconnection, integration and energy/monetary transfers between microgrid, stakeholders and the central grid are deficient
  • consider establishing private contracts between microgrid participants and/or central utility

National Renewable Energy Laboratory (NREL), "Community Shared Solar- Policy and Regulatory Considerations" 2015.

  • community or shared solar is an effective approach to local/distributed generation
  • participants can purchase a "share of solar" which is credited to their energy bill
  • shared solar projects are often hindered by policy or regulations- specifically net metering and interconnection polices, as well as regulations regarding access to benefits of federal/state incentives for such projects
  • design elements of a shared solar program should be established by all relevant stakeholders and can include: ownership organization, eligibility rules, how bill credits will be calculated, more..
  • utility incentive= if state has mandate for renewable energy, utility may generate credits from a shared solar project and apply it to satisfy this requirement
  • net metering=feeds excess power from microgrid to the central grid. Essential to establish limits to system capacity
  • Michigan shared solar investment tax credit? renewable energy credits? Rebate? eligibility to receive benefits? these can impact the economic feasibility

Walker, G., & Devine-Wright, P., "Community renewable energy: What should it mean?" Energy Policy, 36(2), 497-500, 2008.

  • important questions: who is the project by?(process) and who is the project for?(outcome)
  • how will the products of the project be distributed?
  • (open & participatory involvement) + (local & collective benefits)= best case scenario
  • if benefits of community renewables are not distributed fairly, this research claims it project may become contentious and divisive
  • claiming a project is for the community but failing to equitably distribute the costs and benefits will generate pushback
  • awareness and support for renewables can be positively influenced by including locals in project planning
  • investment in such projects can be justified if there is openness and transparency in the process

Zachar, M., Trifkovic, M., Daoutidis, P., "Policy effects on microgrid economics, technology selection, and environmental impact" Computers and Chemical Engineering, 81, 364–375, 2015.

  • although infrastructure is slow to change, policy regimes can expedite the transformation of energy supply
  • microgrids reduce carbon intensity of electricity=lower GHG emission=climate change mitigation technique
  • microgrids provide autonomy to local communities- freedom to choose fuel source, supply technology and mitigate environmental footprint
  • public policy surrounding distributed generation is critical as it can either stimulate or constrain investment/adoption of microgrids by providing stability in regulation, price, etc.
  • results indicate carbon taxes do not have a significant impact on microgrid economics
  • existing tax incentives have inconsistent restrictions on eligible system capacities and technologies
  • ideal if incentives are offered to micro scale systems but not utility systems so that the price is lowered in reference to macrogrid. however, results show their is no significant reduction of cost of local power in this scenario