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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; 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

Identifying Common Errors in Distribution System Models

Conference Record of the IEEE Photovoltaic Specialists Conference

Blakely, Logan; 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; 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.

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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; 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.

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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.

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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
Results 23001–23100 of 99,299
Results 23001–23100 of 99,299