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Visualization Methods for Quasi-Static Time-Series (QSTS) Simulations with High PV Penetration

Conference Record of the IEEE Photovoltaic Specialists Conference

Azzolini, Joseph A.; Reno, Matthew J.; Lave, Matt

Distribution system analysis requires yearlong quasi-static time-series (QSTS) simulations to accurately capture the variability introduced by high penetrations of distributed energy resources (DER) such as residential and commercial-scale photovoltaic (PV) installations. Numerous methods are available that significantly reduce the computational time needed for QSTS simulations while maintaining accuracy. However, analyzing the results remains a challenge; a typical QSTS simulation generates millions of data points that contain critical information about the circuit and its components. This paper provides examples of visualization methods to facilitate the analysis of QSTS results and to highlight various characteristics of circuits with high variability.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Comparison of Ideal Transformer Method and Damping Impedance Method for PV Power-Hardware-In-The-Loop Experiments

Conference Record of the IEEE Photovoltaic Specialists Conference

Summers, Adam K.; Hernandez-Alvidrez, Javier; Darbali-Zamora, Rachid; Reno, Matthew J.; Johnson, Jay B.; Gurule, Nicholas S.

The Ideal Transformer Method (ITM) and the Damping Impedance Method (DIM) are the most widely used techniques for connecting power equipment to a Power-Hardware-in-the-Loop (PHIL) real-time simulation. Both methods have been studied for their stability and accuracy in PHIL simulations, but neither have been analyzed when the hardware is providing grid-support services with volt-var, frequency-watt, and fixed power factor functions. In this work, we experimentally validate the two methods of connecting a physical PV inverter to a PHIL system and evaluate them for dynamic stability and accuracy when operating with grid-support functions. It was found that the DIM Low Pass Lead Filter (LPF LD) method was the best under unity and negative power factor conditions, but the ITM LPF LD method was preferred under positive power factor conditions.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Differential Analysis of the Angle of Incidence Response of Utility-Grade PV Modules

Conference Record of the IEEE Photovoltaic Specialists Conference

King, Bruce H.; Robinson, Charles D.

Anti-reflective coatings (ARCs) are commonly applied to commercial modules to reduce reflection losses and improve energy harvest. Relative performance at low incidence angle is often indistinguishable between different modules and it is only at high incidence angle that performance becomes differentiated. It is also precisely in this range that accurate measurements are the most difficult to obtain, complicating efforts to compare the benefits of different coatings. In this study, the performance of multiple commercial modules with different coatings were compared. A differential approach was employed, facilitating relative comparisons between test devices and a common reference. Using this method, performance differences at high incidence angles could be visualized and quantified. Differential analysis was extended to multiple system performance models in order to predict and quantify potential improvements in annual energy harvest. Improvements were observed upwards of 1% seasonally and 0.5% annually for the best performing coatings. 10° fixed tilt systems were seen to potentially benefit the most from ARCs, while single axis trackers benefitted the least.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Differences in Snow Shedding in Photovoltaic Systems with Framed and Frameless Modules

Conference Record of the IEEE Photovoltaic Specialists Conference

Riley, Daniel; Burnham, Laurie; Walker, Bevan; Pearce, Joshua M.

Energy losses due to snow coverage can be high in climates with large annual snowfall. These losses may be reduced with region-specific system design guidelines. One possible factor in snow retention on PV systems could be frame presence and/or shape. Sandia is studying the effect of module frame presence on photovoltaic module snow shedding for a pair of otherwise-identical PV systems in Vermont. The results of this study provide a summary of the findings after the 2018-2019 winter period. The results clearly show that the presence of a frame inhibits PV performance in mild winter conditions.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

AMI Data Quality and Collection Method Considerations for Improving the Accuracy of Distribution Models

Conference Record of the IEEE Photovoltaic Specialists Conference

Blakely, Logan K.; Reno, Matthew J.; Ashok, Kavya

Spectral clustering is applied to the problem of phase identification of electric customers to investigate the data needs (resolution and accuracy) of advanced metering infrastructure (AMI). More accurate models are required to accurately interconnect high penetrations of PV/DER and for optimal electric grid operations. This paper demonstrates the effects of different data collection implementations and common errors in AMI datasets on the phase identification task. This includes measurement intervals, data resolution, collection periods, time synchronization issues, noisy measurements, biased meters, and mislabeled phases. High quality AMI data is a critical consideration to model correction and accurate hosting capacity analyses.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Effects of Photovoltaic Module Materials and Design on Module Deformation under Load

Conference Record of the IEEE Photovoltaic Specialists Conference

Hartley, James Y.; Maes, Ashley; Owen-Bellini, Michael; Truman, Thomas; Elce, Edmund; Ward, Allan; Khraishi, Tariq; Roberts, Scott A.

Static structural finite element models of an aluminum-framed crystalline silicon (c-Si) photovoltaic (PV) module and a glass-glass thin film PV module were constructed and validated against experimental measurements of deflection under uniform pressure loading. Parametric analyses using Latin Hypercube Sampling (LHS) were performed to propagate simulation input uncertainties related to module material properties, dimensions, and manufacturing tolerances into expected uncertainties in simulated deflection predictions. This exercise verifies the applicability and validity of finite element modeling for predicting mechanical behavior of solar modules across architectures and enables computational models to be used with greater confidence in assessment of module mechanical stressors and design for reliability. Sensitivity analyses were also performed on the uncertainty quantification data sets using linear correlation coefficients to elucidate the key parameters influencing module deformation. This information has implications on which materials or parameters may be optimized to best increase module stiffness and reliability, whether the key optimization parameters change with module architecture or loading magnitudes, and whether parameters such as frame design and racking must be replicated in reduced-scale reliability studies to adequately capture full module mechanical behavior.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Predicting Photovoltaic Module Series Resistance based on Indoor-Aging Tests and Thermal Cycling Cumulative Exposure Estimates

Conference Record of the IEEE Photovoltaic Specialists Conference

Jones, Christian B.; Hobbs, William B.; Libby, Cara; Gunda, Thushara; Hamzavy, Babak

The IEC 61215 and Qualification Plus indoor aging tests are recognized as valuable assessment procedures for identifying photovoltaic (PV) modules that are prone to early-life failures or excessive degradation. However, it is unclear how well the tests match with reality, and if they can predict in-field performance. Therefore, the present work performed indoor-aging thermal cycling tests on pristine-condition modules and evaluated, using in-field current and voltage (I-V) curve scans, modules of the same make and model exposed to the actual environment within a production field. The experiment included the estimate of the overall exposure to thermal cycling in both indoor and outdoor environments, the extraction of the series resistance from the I-V curves, the development of a model based on the indoor results, and finally the testing of the model on outdoor exposure amounts to predict actual changes in resistance. Index Terms - photovoltaic, accelerated aging, series resistance.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Comparison of Ideal Transformer Method and Damping Impedance Method for PV Power-Hardware-In-The-Loop Experiments

Conference Record of the IEEE Photovoltaic Specialists Conference

Summers, Adam K.; Hernandez-Alvidrez, Javier; Darbali-Zamora, Rachid; Reno, Matthew J.; Johnson, Jay B.; Gurule, Nicholas S.

The Ideal Transformer Method (ITM) and the Damping Impedance Method (DIM) are the most widely used techniques for connecting power equipment to a Power-Hardware-in-the-Loop (PHIL) real-time simulation. Both methods have been studied for their stability and accuracy in PHIL simulations, but neither have been analyzed when the hardware is providing grid-support services with volt-var, frequency-watt, and fixed power factor functions. In this work, we experimentally validate the two methods of connecting a physical PV inverter to a PHIL system and evaluate them for dynamic stability and accuracy when operating with grid-support functions. It was found that the DIM Low Pass Lead Filter (LPF LD) method was the best under unity and negative power factor conditions, but the ITM LPF LD method was preferred under positive power factor conditions.

More Details
TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Identifying Common Errors in Distribution System Models

Conference Record of the IEEE Photovoltaic Specialists Conference

Blakely, Logan K.; Reno, Matthew J.; Peppanen, Jouni

This paper discusses common types of errors that are frequently present in utility distribution system models and which can significantly influence distribution planning and operational assessments that rely on the model accuracy. Based on Google Earth imagery and analysis of correlation coefficients, this paper also illustrates some common error types and demonstrates methods to correct the errors. Error types include misla-beled interconnections between customers and service transformers, three-phase customers labeled as single-phase, unmarked transformers, and customers lacking coordinates. Identifying and correcting for these errors is critical for accurate distribution planning and operational assessments, such as load flow and hosting capacity analysis.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Distribution Feeder Fault Comparison Utilizing a Real-Time Power Hardware-in-the-Loop Approach for Photovoltaic System Applications

Conference Record of the IEEE Photovoltaic Specialists Conference

Darbali-Zamora, Rachid; Hernandez-Alvidrez, Javier; Summers, Adam K.; Gurule, Nicholas S.; Reno, Matthew J.; Johnson, Jay B.

Power outages are a challenge that utility companies must face, with the potential to affect millions of customers and cost billions in damage. For this reason, there is a need for developing approaches that help understand the effects of fault conditions on the power grid. In distribution circuits with high renewable penetrations, the fault currents from DER equipment can impact coordinated protection scheme implementations so it is critical to accurately analyze fault contributions from DER systems. To do this, MATLAB/Simulink/RT-Labs was used to simulate the reduced-order distribution system and three different faults are applied at three different bus locations in the distribution system. The use of Real-Time (RT) Power Hardware-in-the-Loop (PHIL) simulations was also used to further improve the fidelity of the model. A comparison between OpenDSS simulation results and the Opal-RT experimental fault currents was conducted to determine the steady-state and dynamic accuracy of each method as well as the response of using simulated and hardware PV inverters. It was found that all methods were closely correlated in steady-state, but the transient response of the inverter was difficult to capture with a PV model and the physical device behavior could not be represented completely without incorporating it through PHIL.

More Details
TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Distribution Feeder Fault Comparison Utilizing a Real-Time Power Hardware-in-the-Loop Approach for Photovoltaic System Applications

Conference Record of the IEEE Photovoltaic Specialists Conference

Darbali-Zamora, Rachid; Hernandez-Alvidrez, Javier; Summers, Adam K.; Gurule, Nicholas S.; Reno, Matthew J.; Johnson, Jay B.

Power outages are a challenge that utility companies must face, with the potential to affect millions of customers and cost billions in damage. For this reason, there is a need for developing approaches that help understand the effects of fault conditions on the power grid. In distribution circuits with high renewable penetrations, the fault currents from DER equipment can impact coordinated protection scheme implementations so it is critical to accurately analyze fault contributions from DER systems. To do this, MATLAB/Simulink/RT-Labs was used to simulate the reduced-order distribution system and three different faults are applied at three different bus locations in the distribution system. The use of Real-Time (RT) Power Hardware-in-the-Loop (PHIL) simulations was also used to further improve the fidelity of the model. A comparison between OpenDSS simulation results and the Opal-RT experimental fault currents was conducted to determine the steady-state and dynamic accuracy of each method as well as the response of using simulated and hardware PV inverters. It was found that all methods were closely correlated in steady-state, but the transient response of the inverter was difficult to capture with a PV model and the physical device behavior could not be represented completely without incorporating it through PHIL.

More Details
TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Visualization Methods for Quasi-Static Time-Series (QSTS) Simulations with High PV Penetration

Conference Record of the IEEE Photovoltaic Specialists Conference

Azzolini, Joseph A.; Reno, Matthew J.; Lave, Matt

Distribution system analysis requires yearlong quasi-static time-series (QSTS) simulations to accurately capture the variability introduced by high penetrations of distributed energy resources (DER) such as residential and commercial-scale photovoltaic (PV) installations. Numerous methods are available that significantly reduce the computational time needed for QSTS simulations while maintaining accuracy. However, analyzing the results remains a challenge; a typical QSTS simulation generates millions of data points that contain critical information about the circuit and its components. This paper provides examples of visualization methods to facilitate the analysis of QSTS results and to highlight various characteristics of circuits with high variability.

More Details
TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Implementation of Temporal Parallelization for Rapid Quasi-Static Time-Series (QSTS) Simulations

Conference Record of the IEEE Photovoltaic Specialists Conference

Azzolini, Joseph A.; Reno, Matthew J.; Montenegro, Davis

Quasi-static time-series (QSTS) analysis of distribution systems can provide critical information about the potential impacts of high penetrations of distributed and renewable resources, like solar photovoltaic systems. However, running high-resolution yearlong QSTS simulations of large distribution feeders can be prohibitively burdensome due to long computation times. Temporal parallelization of QSTS simulations is one possible solution to overcome this obstacle. QSTS simulations can be divided into multiple sections, e.g. into four equal parts of the year, and solved simultaneously with parallel computing. The challenge is that each time the simulation is divided, error is introduced. This paper presents various initialization methods for reducing the error associated with temporal parallelization of QSTS simulations and characterizes performance across multiple distribution circuits and several different computers with varying architectures.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Unintentional Islanding Evaluation Utilizing Discrete RLC Circuit Versus Power Hardware-in-the Loop Method

Conference Record of the IEEE Photovoltaic Specialists Conference

Gonzalez, Sigifredo; Desarden-Carrero, Edgardo; Gurule, Nicholas S.; Aponte-Bezares, Erick E.

The high penetration of photovoltaic (PV) distributed energy resources (DER) facilitates the need for today's systems to provide grid support functions and ride-through voltage and frequency events to minimize the adverse impacts on the distribution power system. These new capabilities and its requirements have created concerns that autonomous unintentional islanding (UI) algorithms are not sufficient to prevent a condition were the loss of utility is detected. Type tests in IEEE 1547-2018 have evolved to thoroughly evaluate DER capabilities and a new method includes power hardware-in-the-loop (PHIL) testing. Sandia National Laboratories is performing a detailed laboratory comparison of the tuned Resistive, Inductive, Capacitive (RLC) circuit method using discrete elements andthe PHIL that applies the PV inverter equipment under test (EUT), real-time simulator, and a power amplifier. The PHIL method allows UI assessments without the need for potentially expensive, large,heat generating discrete loads.

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TYPE Conference Poster YEAR 2019
OSTIScopus

Implementation of Temporal Parallelization for Rapid Quasi-Static Time-Series (QSTS) Simulations

Conference Record of the IEEE Photovoltaic Specialists Conference

Azzolini, Joseph A.; Reno, Matthew J.; Montenegro, Davis

Quasi-static time-series (QSTS) analysis of distribution systems can provide critical information about the potential impacts of high penetrations of distributed and renewable resources, like solar photovoltaic systems. However, running high-resolution yearlong QSTS simulations of large distribution feeders can be prohibitively burdensome due to long computation times. Temporal parallelization of QSTS simulations is one possible solution to overcome this obstacle. QSTS simulations can be divided into multiple sections, e.g. into four equal parts of the year, and solved simultaneously with parallel computing. The challenge is that each time the simulation is divided, error is introduced. This paper presents various initialization methods for reducing the error associated with temporal parallelization of QSTS simulations and characterizes performance across multiple distribution circuits and several different computers with varying architectures.

More Details
TYPE Conference Poster YEAR 2019
DOIOSTIScopus

Single Diode Parameter Extraction from In-Field Photovoltaic I-V Curves on a Single Board Computer

Conference Record of the IEEE Photovoltaic Specialists Conference

Jones, Christian B.; Hansen, Clifford

In this paper, we present a new, light-weight approach for extracting the five single diode parameters (IL, Io, RS, RSH, and nNsVt) for advanced, in-field monitoring of in situ current and voltage (I-V) tracing devices. The proposed procedure uses individual I-V curves, and does not require the irradiance or module temperature measurement to calculate the parameters. It is suitable for operation on a small, single board computer at the point of I-V curve measurement. This allows for analysis to occur in the field, and eliminates the need to transfer large amounts of data to centralized databases. Observers can receive alerts directly from the in-field devices based on the extraction, and analysis of the commonly used single diode equivalent model parameters. This paper defines the approach and evaluates its accuracy by subjecting it to I-V curves with known parameters. Its performance is defined using actual I-V curves generated from an in situ scanning devices installed within an actual photovoltaic production field. The algorithm is able to operate at a high accuracy for multiple module types and performed well on actual curves extracted in the field.

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TYPE Conference Poster YEAR 2019
DOIOSTIScopus
Results 24601–24800 of 101,000
Results 24601–24800 of 101,000
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