#Webinar – Assessment of Benefits Derived from Improved Reliability and Resiliency in Utility-owned #Microgrid

Burns & McDonnell is partnering with Transmission & Distribution World magazine


Recent efforts by electric utilities to implement new technologies in existing systems are changing our understanding of the electric grid. New capabilities are being introduced by these technologies and have resulted in the design of innovative system configurations. The deployment of microgrids exemplifies this, and is considered an important turning point for distribution system engineering. Because microgrid development empowers several technologies such as distributed generation (DG) (e.g. combined heat and power (CHP), solar photovoltaic (PV), and wind), energy storage and demand response capable devices, their implementation process is more efficient. ComEd, an electric utility serving the north of Illinois and the city of Chicago, has proposed a microgrid pilot program that will deploy utility-owned microgrids in five different locations within the city of Chicago. The system performance goals established for the microgrids consist of reducing outage time for critical loads, reducing emissions and improving energy efficiency.

This webinar will review the technical and financial assessment of the reliability improvement expected in a public-purpose community microgrid owned and operated by an electric utility. The results of the study include the estimated value of reliability improvement, distribution of benefits by type of customer, and forecast of total sustained interruption costs. 


Design and Research on the LCL Filter in Three-Phase #PV Grid-Connected #Inverters

Abstract—Aiming at the problem of filtering in the three-phase PV grid-connected inverters, the mathematics models for L filter and LCL filter are established. The values of capacitances and inductances are calculated by analyzing the related constraint conditions for the main parameters of LCL filter. There are two ways to increase the value of damping resistor of the filter capacitor. The impacts on the stability and filtering property, in both ways, are analyzed. The simulation result indicated that the LCL filter achieve the best performance than L filter and LC filter. Under the prerequisite of increasing system stability, parallel resistor is even more advantageous than series resistor. And the validity of theoretical results is confirmed.


Design and Control of LCL Filter Interfaced Grid Connected #Solar #Photovoltaic System by Using Power Balance Theory

Abstract: In this paper solar photovoltaic system connected to the utility grid is design and simulated. The utility grid and SPV system are coupled with current controlled voltage source (VSC) and LCL filter. LCL improves stability of the system .The system is controlled through power balance theory method. For grid synchronization and power control, control algorithm is required also requires power conditioning unit for smooth operation, Power balance theory (PBT) is used as control strategy. PBT is simple and can be achieved easily. The grid connected pv system consist of – Photovoltaic (PV), Incremental Conductance MPPT method, LCL filter, three phase utility grid, power balance theory. Source/grid voltages are used as reference for generating templates. This is the principle behind the algorithm implementation. In order to generate templates mathematical equations are required. Incremental conductance method is used for simplifying the implementation of the system the grid connected Photovoltaic system (PV) is connected to a non linear load having intermittent components as dc/dc. This system is capable of eliminating harmonics and compensating the reactive power.SPV array using indirect current control scheme. MATLAB/SIMULINK is used for demonstrate the system.


Maximizing Output Power from #Solar Cells/Panels through the Development of an Integrated Voltage Regulator/MPPT Circuit

Abstract—This paper presents the initial results of our research effort to fully integrate a voltage regulator with a Maximum Power Point Tracking (MPPT) circuit in order to harvest maximum power from solar cells or panels. We take a novel approach to emulate the inductor in a buck-boost voltage regulator using a Generalized Impedance Converter (GIC), thereby eliminating the requirement for the grounded inductor which impedes full integration. LTSPICETM models are developed to compare a traditional “inductive” voltage regulator with a “GIC” voltage regulator, and experimental results are discussed. Component size, switching frequency, and loadmatching are optimized to achieve maximum efficiency; however, GIC operational-amplifier power consumption was an obstacle to high-efficiency operation.




Energy storage systems coupled to solar photovoltaic arrays are set to play a major role in the future energy landscape, both on and off the grid. The high variability of solar power and consumer loads can be overcome with rapid battery response rates. In this work power data measured at 1 Hz from the densely clustered arrays of the KIT 1 MWp solar installation are analysed using statistical techniques in order to characterise the variability of single arrays as well as that of the system as a whole. The relationship between correlation and distance is examined in detail: the smoothing that results from decorrelation can be used as an additional mitigation factor in the design of small-scale collections of solar systems, especially in the context of residential and district storage solutions. In this context, the preliminary results of impulse- response tests performed on several commercially available household storage systems show a large discrepancy in the ability of different systems to successfully compensate power fluctuations. While the economic effects of sluggish control algorithms are relatively small in the grid-connected context, in off-grid scenarios they can affect power quality, so that the widespread deployment of such systems necessitates fast response rates.




The solar resource remains extremely underutilised in a synthetic fashion. With increasing clean water demands and decreasing clean water sources, solar desalination becomes all the more relevant. Direct absorption solar collectors offer improved efficiency over traditional surface absorbing collectors because they have fewer heat resistance steps and have the ability to utilise higher radiation fluxes. Carbon black- based nanofluids, with concentrations below 0.1%, were compared with each other and with the base fluid of salt water in a concentrated solar power scenario. A 1 m2 concentrating unit using a two-axis tracking system with two mirrors and a 1 m2 Fresnel lens was used to concentrate solar radiation on a 10 cm2 direct absorption solar collector flow cell. An optimum concentration of 0.001 vol % carbon black was found to show a 94 % increase in heating rate compared to that of salt water. This was accomplished with a collector efficiency of 59 %, 28 % higher than that of salt water. The overall efficiency of the system was 28 %. This low efficiency can be attributed to the high optical losses (50 % − 70 %) present in the concentrating unit.


Towards an International Guideline for Yield Analysis for #Solar Thermal Power Plants – PDF

Markus Eck, Tobias Hirsch

University of Applied Science Osnabrück, Germany, m.eck@hs-osnabrueck.de

German Aerospace Center (DLR), Institute of Solar Research, Germany, tobias.hirsch@dlr.de 


Solar Thermal Electricity (STE) Plants are a utility scale technology for solar electricity production that offer full dispatchability thanks to integrated storage capacity. Due to the huge capacity and thus investment, each project is subject to a sound project development process. In each step of this process an adequate yield analysis is a crucial task to estimate the expected electricity yield and the achievable levelized cost of electricity (LCOE) or internal rate of return (IRR).
Despite the significance of this task no international guideline exists for the yield analysis of STE plants. This situation causes investors to increase their risk surcharges and with that increase the LCOE or reduce the IRR accordingly. To improve this situation an international working group has been established to develop a guideline for yield analysis that may serve as a basis for an international standard in the future.
The intention of this conference paper is to introduce the guideline document to the South African STE community. The paper will provide a meaningful introduction to the concepts of the guideline, its structure, and the status of its documents. It will also invite to contribute to future extensions of the guideline, e.g. by providing modeling approaches and system parameters for present and upcoming STE technologies


Critical weather situations for renewable energies – Part B: Low stratus risk for #solar power http://photovoltaic.pw/2iQaMb7

Accurately predicting the formation, development and dissipation of fog and low stratus (LS) still poses a challenge for numerical weather prediction (NWP) models. Errors in the low cloud cover NWP forecasts directly impact the quality of photovoltaic (PV) power prediction. On days with LS, day-ahead forecast errors of Germany-wide PV power frequently lie within the magnitude of the balance energy and thus pose a challenge for maintaining grid stability. An indication in advance about the possible occurrence of a critical weather situation such as LS would represent a helpful tool for transmission system operators (TSOs) in their day-to-day business. In the following, a detection algorithm for low stratus risk (LSR) is developed and applied as post-processing to the NWP model forecasts of the regional non-hydrostatic model COSMO-DE, operational at the German Weather Service. The aim of the LSR product is to supply day-ahead warnings and to support the decision making process of the TSOs. The quality of the LSR is assessed by comparing the computed regions of LSR occurrence with a satellite based cloud classification product from the Nowcasting Satellite Facility (NWCSAF). The results show that the LSR provides additional information that should in particular be useful for risk adverse users.