Joseph A. Azzolini

Sandia National Laboratories · Electric Power Systems Research

High penetrations of residential solar PV can cause voltage issues on low-voltage (LV) secondary networks. Distribution utility planners often utilize model-based power flow solvers to address these voltage issues and accommodate more PV installations without disrupting the customers already connected to the system. These model-based results are co...

Residential solar photovoltaic (PV) systems are interconnected with the distribution grid at low-voltage secondary network locations. However, computational models of these networks are often oversimplified or non-existent, which makes it challenging to determine the operational impacts of new PV installations at those locations. In this work, a mo...

The wide variety of inverter control settings for solar photovoltaics (PV) causes the accurate knowledge of these settings to be difficult to obtain in practice. This paper addresses the problem of determining inverter reactive power control settings from net load advanced metering infrastructure (AMI) data. The estimation is first cast as fitting...

This report summarizes the work performed under a project funded by U.S. DOE Solar Energy Technologies Office (SETO), including some updates from the previous report SAND2022-0215, to use grid edge measurements to calibrate distribution system models for improved planning and grid integration of solar PV. Several physics-based data-driven algorithm...

Today, hydrogen is overwhelmingly produced through natural gas reforming which involves significant carbon emissions. Green hydrogen production from water and renewable energy promises over 80% reduction in carbon emission, but the technology for large-scale (megawatt to gigawatt) solar- or wind-powered hydrogen production has yet to be developed....

Frequent changes in penetration levels of distributed energy resources (DERs) and grid control objectives have caused the maintenance of accurate and reliable grid models for behind-the-meter (BTM) photovoltaic (PV) system impact studies to become an increasingly challenging task. At the same time, high adoption rates of advanced metering infrastru...

The proper coordination of power system protective devices is essential for maintaining grid safety and reliability but requires precise knowledge of fault current contributions from generators like solar photovoltaic (PV) systems. PV inverter fault response is known to change with atmospheric conditions, grid conditions, and inverter control setti...

Conservation voltage reduction (CVR) is a common technique used by utilities to strategically reduce demand during peak periods. As penetration levels of distributed generation (DG) continue to rise and advanced inverter capabilities become more common, it is unclear how the effectiveness of CVR will be impacted and how CVR interacts with advanced...

The increasing availability of advanced metering infrastructure (AMI) data has led to significant improvements in load modeling accuracy. However, since many AMI devices were installed to facilitate billing practices, few utilities record or store reactive power demand measurements from their AMI. When reactive power measurements are unavailable, s...

Distributed generation (DG) sources like photovoltaic (PV) systems with advanced inverters are able to perform grid-support functions, like autonomous Volt-VAR that attempts to mitigate voltage issues by injecting or consuming reactive power. However, the Volt-VAR function operates with VAR priority, meaning real power may be curtailed to provide a...

Steam methane reforming of natural gas emits about 12 kg of carbon dioxide for 1 kg of hydrogen. Water electrolysis offers an alternative for H2 production, but today’s electrolyzers consume over 55 kWh of electricity for 1 kg of H2. Grid-powered water electrolysis would emit less CO2 when the carbon intensity for grid power falls below 0.22 kg-CO2...

Accurate models of voltage regulating devices are required for reliably executing distribution system analysis and planning tasks. However, these models are often created and updated manually, meaning they are prone to input errors and outdated settings. In this paper, data-driven methods are presented to characterize several physical parameters of...

This report summarizes the work performed under a project funded by U.S. DOE Solar Energy Technologies Office (SETO) to use grid edge measurements to calibrate distribution system models for improved planning and grid integration of solar PV. Several physics-based data-driven algorithms are developed to identify inaccuracies in models and to bring...

Advanced solar PV inverter control settings may not be reported to utilities, or may be changed without notice. This paper develops an estimation method for determining a fixed power factor control setting of a behind-the-meter (BTM) solar PV smart inverter. The estimation is achieved using linear regression methods with historical net load advance...

This presentation summarizes the work performed under a project funded by U.S. DOE Solar Energy Technologies Office (SETO) to use grid edge measurements to calibrate distribution system models for improved planning and grid integration of solar PV. Several physics-based data-driven algorithms are developed to identify inaccuracies in models and to...

By strategically curtailing active power and providing reactive power support, photovoltaic (PV) systems with advanced inverters can mitigate voltage and thermal violations in distribution networks. Quasi-static time-series (QSTS) simulations are increasingly being utilized to study the implementation of these inverter functions as alternatives to...

The rising penetration levels of photovoltaic (PV) systems within distribution networks has driven considerable interest in the implementation of advanced inverter functions, like autonomous Volt-Var, to provide grid support in response to adverse conditions. Quasi-static time-series (QSTS) analyses are increasingly being utilized to evaluate advan...

Recent trends in PV economics and advanced inverter functionalities have contributed to the rapid growth in PV adoption; PV modules have gotten much cheaper and advanced inverters can deliver a range of services in support of grid operations. However, these phenomena also provide conditions for PV curtailment, where high penetrations of distributed...

Grid support functionalities from advanced PV inverters are increasingly being utilized to help regulate grid conditions and enable high PV penetration levels. To ensure a high degree of reliability, it is paramount that protective devices respond properly to a variety of fault conditions. However, while the fault response of PV inverters operating...

The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modeling and impact analysis. Unlike conventional scenario-based studies, quasi-static time-series (QSTS) simulations can realistically model time-dependent voltage controllers and the...

Distributed photovoltaic (PV) systems equipped with advanced inverters can control real and reactive power output based on grid and atmospheric conditions. The Volt-Var control method allows inverters to regulate local grid voltages by producing or consuming reactive power. Based on their power ratings, the inverters may need to curtail real power...

The use of hydrogen as a zero-emission fuel and energy storage medium has the potential to play an increasing role in the decarbonization of our energy and transportation infrastructures when produced using renewable energy resources. This work proposes a load-managing photovoltaic (PV) system for driving hydrogen production that eliminates the nee...

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 ti...

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 lo...

Nearly all photovoltaic (PV) systems involve power management and/or conversion devices. Each of these devices introduces a power loss and has an associated monetary cost. In this paper, a direct-coupled load-managing PV system is proposed that promises both a lower cost and a higher efficiency than conventional systems. Against the prevailing wisd...

Distribution system analysis with high penetrations of distributed PV require quasi-static time-series (QSTS) analysis to model the variability introduced on the distribution system, but current QSTS algorithms are prohibitively burdensome and computationally intensive. This paper proposes a variable time-step algorithm to calculate the critical ti...

We proposed and demonstrated a load-managing photovoltaic (PV) system that significantly reduces the levelized cost of electricity over conventional PV systems. Instead of managing the PV power, the system manages the number of loads connected to the PV array throughout the day to maximize the utilization efficiency of available PV power without a...

Conventional photovoltaic (PV) systems are designed to compensate for the intermittent nature of solar energy, and therefore require multiple power-managing components like storage batteries, maximum power point trackers, and charge controllers. Each of these components adds an additional cost and has an associated power loss. In this paper, we pre...

The global energy demands are predicted to reach 46 terawatts by 2100. Solar photovoltaics has to be deployed at a scale of tens of peak terawatts in order to meet a meaningful portion of the demands. The enormous scale required creates a number of roadblocks for photovoltaic technologies, which are unprecedented in other semiconductor technologies...