Results for “trip” — Page 22

DOE OSTI2023

Large Angle Deviation in Grid-Following IBRs Upon Grid Voltage Dip

In the 2021 Texas Odessa large-scale solar PV tripping events, phase-locked-loop (PLL) loss of synchronism is identified as a major cause of solar PV tripping. When solar PVs detected a large phase angle deviation (e.g., 10 degrees), tripping commands were initiated. Here, the large phase angle deviation was triggered by a transmission line fault 200 miles away, which in turn led to approximately 30% voltage drop in the 345-kV system. This paper offers a plausible reason why grid-following inverter-based resources (IBRs) may experience a large angle deviation upon grid voltage dip. Critical operating conditions contributing to such phenomena are identified via analysis and their effects are demonstrated using electromagnetic transient (EMT) simulation. Furthermore, the effect of converter control, e.g., grid-following control vs. grid-forming control, is examined. It is found from EMT simulation results that frequency and voltage control are helpful in mitigating angle deviation. Furthermore, linear block diagrams are derived to examine why frequency control can effectively suppress large angle deviation.

14 SOLAR ENERGY↗

DOE OSTI2022

Neural Network-Based Electric Vehicle Range Prediction for Smart Charging Optimization

Range prediction is a standard feature in most modern road vehicles, allowing drivers to make informed decisions about when to refuel. Most vehicles make range predictions through data- or model-driven means, monitoring the average fuel consumption rate or using a tuned vehicle model to predict fuel consumption. The uncertainty of future driving conditions makes the range prediction problem challenging, particularly for less pervasive battery electric vehicles (BEV). Most contemporary machine learning-based methods attempt to forecast the battery SOC discharge profile to predict vehicle range. In this work, we propose a novel approach using two recurrent neural networks (RNNs) to predict the remaining range of BEVs and the minimum charge required to safely complete a trip. Each RNN has two outputs that can be used for statistical analysis to account for uncertainties; the first loss function leads to mean and variance estimation (MVE), while the second results in bounded interval estimation (BIE). These outputs of the proposed RNNs are then used to predict the probability of a vehicle completing a given trip without charging, or if charging is needed, the remaining range and minimum charging required to finish the trip with high probability. Training data was generated using a low-order physics model to estimate vehicle energy consumption from historical drive cycle data collected from medium-duty last-mile delivery vehicles. Here, the proposed method demonstrated high accuracy in the presence of day-to-day route variability, with the root-mean-square error (RMSE) below 6% for both RNN models.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2022

Attributes of Bi-Directional Turbomachinery for Pumped Thermal Energy Storage

Abstract In this paper, we (i) present a methodology for determining the aerodynamic performance of bi-directional turbomachines for pumped thermal energy storage, i.e., turbomachines designed to operate as a compressor in one direction, and then as a turbine in the opposite direction, (ii) carry out performance computations for such turbomachines, and (iii) propose principles for conceptual design of these devices. Focus is placed on using the energy storage cycle not only to identify the novel requirements placed on bi-directional turbomachines but also to estimate the effect of these requirements on the efficiency of the energy storage process. In particular, the difference between aerodynamic loading in forward and in backward operation causes the blading to work at incidences leading to the performance below maximum efficiency, resulting in a lower round-trip efficiency. The description of the design principles includes determination of the number of stages, definition of nondimensional parameters for blading selection, and optimization of two-dimensional blading for bi-directional operation. The assessment of stage count shows the relationship between relative Mach number, pressure ratio, and round-trip efficiency. The nondimensional parameters are assessed through a bi-directional analogue to existing “Smith charts,” for the efficiency of single-direction turbomachines, as a function of camber and stagger. The blade shape evaluation and optimization show how the blade profile can be modified to address the requirements of a bi-directional turbomachine, enabling an increase in round-trip efficiency of two percentage points compared to a baseline double circular arc configuration.

Engineering↗

DOE OSTI2022

Data-Driven Prediction and Optimization of Energy Use for Transit Fleets of Electric and ICE Vehicles

Due to the high upfront cost of electric vehicles, many public transit agencies can afford only mixed fleets of internal combustion and electric vehicles. Optimizing the operation of such mixed fleets is challenging because it requires accurate trip-level predictions of electricity and fuel use as well as efficient algorithms for assigning vehicles to transit routes. We present a novel framework for the data-driven prediction of trip-level energy use for mixed-vehicle transit fleets and for the optimization of vehicle assignments, which we evaluate using data collected from the bus fleet of CARTA, the public transit agency of Chattanooga, TN. We first introduce a data collection, storage, and processing framework for system-level and high-frequency vehicle-level transit data, including domain-specific data cleansing methods. We train and evaluate machine learning models for energy prediction, demonstrating that deep neural networks attain the highest accuracy. Based on these predictions, we formulate the problem of minimizing energy use through assigning vehicles to fixed-route transit trips. We propose an optimal integer program as well as efficient heuristic and meta-heuristic algorithms, demonstrating the scalability and performance of these algorithms numerically using the transit network of CARTA.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2024

Community Public Mobility Using On-Demand, Low-Speed Electric Vehicles: A Case Study in Downtown St. Louis, Missouri

Legacy fixed route transit systems designed to serve commuters struggle to provide efficient and effective service for short neighborhood trips and for population groups unable to access and egress transit stops using active modes (e.g., elderly, disabled). Neighborhood on-demand transit (ODT) services using low-speed electric vehicles (LSEV) are an innovative technological solution that can help fill this gap in service (e.g., short, high-frequency trips) for diverse populations and trip types. This study evaluated user characteristics and travel behavior for a neighborhood ODT service (using LSEVs) in downtown St. Louis, Missouri using responses from a community survey (n=244), ridership data, and vehicle trajectory information. A comparative analysis between neighborhood ODT, fixed route transit, and transportation network companies (TNC) was also conducted from the perspectives of total travel time, cost, and greenhouse gas emissions. Ultimately, the goal of the analysis was to motivate and inform holistic public mobility systems where different services are optimized to meet specific community needs. Findings indicate that the neighborhood ODT was effective at reaching diverse populations (elderly (20%), lower income (27%), and households with limited access to private vehicles (34%)). ODT reduced total travel time by 32% compared to fixed route transit, produced 2.4 - 4.3 times less greenhouse gas emissions per passenger mile (compared to transit and TNCs), and was more affordable (free to users) than alternative options ($1 for transit, $10-12 for TNCs). Overall satisfaction rates were high, with 80% of respondents rating the service a 4 or 5 out of 5.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2026

WholeTraveler Anonymized Data Phase 2

Phase 2 of the WholeTraveler study consisted of a global positioning system (GPS) data collection. Phase 2 started immediately after the completion of the Phase 1 survey for any respondent who opted into Phase 2. The raw locational data collected have been processed into identified "trips" and some of those trips into identified "trip chains." Data from Phase 1 and Phase 2 are linked by a unique respondent identifier. Anonymized versions of the Phase 1 and Phase 2 data are both available on Livewire.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2026

1991 Boston Household Travel Survey

The Central Transportation Planning Staff conducted a household travel survey in 1991, featuring demographic, socioeconomic, and travel features of 2,347 households, generating 39,372 weekday trips. The survey took the form of an activity-based travel diary that each subject household filled out for one weekday. The data was used to estimate new models for trip generation, automobile ownership, trip distribution, and mode choice.

1Hz data↗

DOE OSTI2026

1990 CATS Household Travel Survey

The Chicago Area Transportation Study (CATS) 1990 Household Travel Survey was a self-administered mail-out mail-back survey. The purpose of the study was to update existing data on travel patterns and characteristics of Chicago residents. CATS surveyed the region on a county-by-county basis with the Chicago Central Business District in collaboration with the Urban Transportation Center of the University of Illinois. The study gathered demographic and travel behavior data from residents of northeastern Illinois who were 14 years old or older. 19,314 households participated in the survey. The study focused on non-work travel by motorized vehicle and by foot, and residents recorded their trips on a single travel day. Transportation-related variables include trip origin and destination, trip purpose, travel time, mode of travel used, vehicle occupancy, and walking distance (if that transit mode was involved).

1Hz data↗

DOE OSTI2026

2000 Delaware Valley Regional Planning Commission Household Travel Survey

This survey was conducted from March through December 2000 under the auspices of the Delaware Valley Regional Planning Commission and the Southern Jersey Transportation Planning Organization and funded through the Pennsylvania and New Jersey departments of transportation. Cambridge Systematics provided quality assurance under a subcontract to NuStats. The purpose of the survey was to obtain information about work and non-work trip generation, trip distribution, modal choice, and traffic assignment, as well as to obtain data on average vehicle occupancy. The dataset contains demographic and travel data on 5,677 households in the 14-county study area. Of those households, 4,217 were from the 10-county Delaware Valley region of Pennsylvania and New Jersey. The 4,217 Delaware Valley households, when weighted, represent 9,358 members and 6,069 vehicles, and reported a total of 31,631 trips.

1Hz data↗

DOE OSTI2026

1988/1989 Maricopa Household Travel Study

This study was commissioned by the Maricopa Association of Governments (MAG) Transportation and Planning Office. The primary objectives of this study were to update the trip generation rates used in the MAG travel demand forecasting process and to provide data to validate the MAG trip distribution model. Demographic, socioeconomic, and travel data was collected for 2,992 households residing within the MAG Urban Planning Area. Respondents were asked to record their travel and activities for a 24-hour period. A total of 26,733 trips were recorded by 6,463 people.

1Hz data↗

DOE OSTI2026

Sacramento Area Council of Governments's 1991 Household Travel Survey

The Sacramento Area Council of Governments's 1991 Household Travel Survey was conducted in conjunction with the California State Department of Transportation, and provides a detailed survey of travel behavior of 3,942 households in the Sacramento region. The region includes all of Sacramento, Yolo, Yuba, and Sutter counties, as well as the western portions of Placer and El Dorado counties. The purpose of the survey was to obtain up-to-date information on the socioeconomic, demographic, and travel characteristics of the population. During their travel day, participating household members were asked to record travel information in a diary for the specified 24-hour period. The information documented by respondents includes trip activities, mode of transportation, trip times, and trip location. Demographic information includes gender, age, employment status, household income, and household size, as well as whether the respondent held a valid driver's license, whether the respondent was a student, and whether the respondent owned or rented a home.

1Hz data↗

DOE OSTI2026

The 1990 San Francisco Bay Area Metropolitan Transportation Commission Household Survey

The San Francisco Bay Area's Metropolitan Transportation Commission (MTC) and the regional transportation planning agency for the nine-county Bay Area conducted the survey. The basic purpose for the survey was for the development of travel demand models to simulate the various components of travel behavior: auto ownership, trip frequency (trip generation), and the distribution of trips between origins and destinations by travel mode. Planners at MTC envisioned the 1990 survey as the first wave of a multi-wave household panel survey designed to capture both short- and long-term changes in regional travel behavior. The 1990 survey collected single-weekday travel data from nearly 9,900 Bay Area households and multiple-weekday travel data from nearly 1,500 households. The 1990 survey effort also included a separate sub-project, funded by the Bay Area Rapid Transit (BART) District, to collect multiple-weekday travel data from 1,000 BART-using households. The BART survey and the MTC multiple-weekday survey were completed in the spring of 1990; the MTC single-weekday survey was continued and completed during the autumn of 1990.

1Hz data↗

DOE OSTI2026

1990 St. Louis Region Travel Survey

The 1990 St. Louis Region Travel Survey was performed in the fall of 1990 for the St. Louis region. The study was done for the East-West Gateway Coordinating Council by Barton-Aschman Associates, Inc., with assistance from NSI Research Group. The area surveyed included the city of St. Louis, St. Louis County, and parts of Jefferson County, Madison County, St. Clair County, Monroe County, and St. Charles County. The survey was used primarily for the calibration of trip production models. Other uses will include the calibration of trip attraction models and trip distribu¬tion models. The total number of completed, useable household samples for the survey area totaled 1,446.

1Hz data↗

DOE OSTI2026

2002 St. Louis Region Travel Survey

The 2002 St. Louis Household Travel Survey entailed the collection of weekday travel behavior characteristics of households residing in each of the eight counties that comprise the St. Louis region. In addition to collecting basic demographic and socioeconomic information about each household and its members, the survey documented specific characteristics of activities and trips, including the number and purpose of trips, trip duration, time of day, mode of transportation, and specifics of school- and work-related travel. The survey instruments contained three components: 1) the recruitment questionnaire, 2) the travel log, and 3) the retrieval questionnaire. In total, 7,046 households were recruited to participate in the study via telephone interview. Of these, 5,094 completed travel logs during a specific 24-hour period, and the information was retrieved from all household members, regardless of age. Demographic information for this study includes age, gender, education level, employment status, and household income.

1Hz data↗

DOE OSTI2026

Atlanta—1991 Household Interview Survey

The Atlanta Regional Commission conducted a Household Travel Survey in 1991 to capture the reality of the locale, including infrastructure improvements—such as new highways, rail, and housing developments—additional households, income, trip chaining, and telecommuting, as well as other typical demographic characteristics. The survey collected demographic, socioeconomic, and travel information on work and non-work travel behavior. Travel data includes trip generation, trip distribution, and modal choice for 3,626 households that completed a travel log.

1Hz data↗

DOE OSTI2025

2017 National Household Travel Survey - Arizona Add-On

# 2017 National Household Travel Survey – Arizona Add-On The Arizona add-on survey supplements the 2017 National Household Travel Survey (NHTS) with additional household samples and detailed travel behavior for an assigned travel day. ## Data Collection Agency The Federal Highway Administration conducted the NHTS and corresponding add-on surveys. ## Methodology This survey documents the demographic, attitudinal, and travel behavior for all members of 2,987 households, as collected from April 2016 to April 2017. Daily travel details provide insight into work and school commutes, non-emergency medical trips, shopping trips, and even how travel differs in the summer and on weekends as compared to a typical weekday when school is in session. When statistically weighted to adjust for survey biases, the data demographically represents all Americans and is appropriate for analysis at the national and census region levels. ## Survey Records Survey records include a total of 6,081 participants. ## Transportation Data The NHTS Arizona add-on data package contains a demographic and socioeconomic composition of 6,081 people from 2,987 households in Arizona, as well as detailed information on the travel behavior of each household for a designated 24-hour period. The survey logged more than 258,000 vehicle miles of travel by participants during 19,779 trips. For details on available data and variable definitions, see the [data dictionary](https://www.nrel.gov/media/docs/libraries/tsdc/data-elements-2017.xlsx?sfvrsn=ad09b18c_3). Transportation data are available as zipped files. [Download Winzip](http://www.winzip.com/downwz.htm).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2025

2017 National Household Travel Survey - Arizona Add-On

# 2017 National Household Travel Survey – Arizona Add-On The Arizona add-on survey supplements the 2017 National Household Travel Survey (NHTS) with additional household samples and detailed travel behavior for an assigned travel day. ## Data Collection Agency The Federal Highway Administration conducted the NHTS and corresponding add-on surveys. ## Methodology This survey documents the demographic, attitudinal, and travel behavior for all members of 2,987 households, as collected from April 2016 to April 2017. Daily travel details provide insight into work and school commutes, non-emergency medical trips, shopping trips, and even how travel differs in the summer and on weekends as compared to a typical weekday when school is in session. When statistically weighted to adjust for survey biases, the data demographically represents all Americans and is appropriate for analysis at the national and census region levels. ## Survey Records Survey records include a total of 6,081 participants. ## Transportation Data The NHTS Arizona add-on data package contains a demographic and socioeconomic composition of 6,081 people from 2,987 households in Arizona, as well as detailed information on the travel behavior of each household for a designated 24-hour period. The survey logged more than 258,000 vehicle miles of travel by participants during 19,779 trips. For details on available data and variable definitions, see the [data dictionary](https://www.nrel.gov/media/docs/libraries/tsdc/data-elements-2017.xlsx?sfvrsn=ad09b18c_3). Transportation data are available as zipped files. [Download Winzip](http://www.winzip.com/downwz.htm).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2025

2017 National Household Travel Survey - Arizona Add-On

# 2017 National Household Travel Survey – Arizona Add-On The Arizona add-on survey supplements the 2017 National Household Travel Survey (NHTS) with additional household samples and detailed travel behavior for an assigned travel day. ## Data Collection Agency The Federal Highway Administration conducted the NHTS and corresponding add-on surveys. ## Methodology This survey documents the demographic, attitudinal, and travel behavior for all members of 2,987 households, as collected from April 2016 to April 2017. Daily travel details provide insight into work and school commutes, non-emergency medical trips, shopping trips, and even how travel differs in the summer and on weekends as compared to a typical weekday when school is in session. When statistically weighted to adjust for survey biases, the data demographically represents all Americans and is appropriate for analysis at the national and census region levels. ## Survey Records Survey records include a total of 6,081 participants. ## Transportation Data The NHTS Arizona add-on data package contains a demographic and socioeconomic composition of 6,081 people from 2,987 households in Arizona, as well as detailed information on the travel behavior of each household for a designated 24-hour period. The survey logged more than 258,000 vehicle miles of travel by participants during 19,779 trips. For details on available data and variable definitions, see the [data dictionary](https://www.nrel.gov/media/docs/libraries/tsdc/data-elements-2017.xlsx?sfvrsn=ad09b18c_3). Transportation data are available as zipped files. [Download Winzip](http://www.winzip.com/downwz.htm).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗