Ram Rajagopal

Ram Rajagopal
Stanford University | SU

About

231
Publications
41,053
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
5,233
Citations

Publications

Publications (231)
Article
The rapid expansion of Advanced Meter Infrastructure (AMI) has dramatically altered the energy information landscape. However, our ability to use this information to generate actionable insights about residential electricity demand remains limited. In this research, we propose and test a new framework for understanding residential electricity deman...
Preprint
Full-text available
The rapid expansion of Advanced Meter Infrastructure (AMI) has dramatically altered the energy information landscape. However, our ability to use this information to generate actionable insights about residential electricity demand remains limited. In this research, we propose and test a new framework for understanding residential electricity deman...
Article
To prepare for rapid growth in global electric vehicle adoption, grid and policy planners depend on detailed forecasts of future charging demand. In this paper we propose a novel holistic, scalable, probabilistic framework to produce large-scale estimates of electric vehicle charging load for long-term planning that capture real drivers’ charging p...
Article
While photovoltaic (PV) systems are being installed at an unprecedented rate, it is challenging to keep track of them due to their decentralized character and large number. In this paper, we present the 3D-PV-Locator for large-scale detection of roof-mounted PV systems in three dimensions (3D). The 3D-PV-Locator combines information extracted from...
Article
Transportation electrification is forecast to bring millions of new electric vehicles to roads worldwide this decade. Planning to support those vehicles depends on detailed scenarios of their electricity demand in both uncontrolled and controlled or smart charging scenarios. In this paper, we present a novel modeling approach to enable rapid genera...
Article
Full-text available
Understanding how the COVID-19 pandemic has altered electricity consumption can provide insights into society's responses to future shocks and other extreme events. We quantify changes in electricity consumption in 58 different countries/regions around the world from January-October 2020, and examine how those changes relate to government restricti...
Article
As wildfire risk in the western U.S. grows due to climate change, the frequency and duration of public safety power shutoffs (PSPSs) are expected to increase. Surveying California residents (n = 804), we identify four respondent groupings based on PSPS experience and concern about future power outages. We find that those with higher levels of exper...
Preprint
Charging infrastructure is the coupling link between power and transportation networks, thus determining charging station siting is necessary for planning of power and transportation systems. While previous works have either optimized for charging station siting given historic travel behavior, or optimized fleet routing and charging given an assume...
Article
Full-text available
Distributed energy resources can enhance community resilience to power outages in the aftermath of natural disasters. This article presents a method to quantify the resilience value that rooftop solar systems can provide to residential neighborhoods. Homes are grouped into geographical clusters to simulate the effect of sharing energy when a disast...
Preprint
Full-text available
Planning to support widespread transportation electrification depends on detailed estimates for the electricity demand from electric vehicles in both uncontrolled and controlled or smart charging scenarios. We present a modeling approach to rapidly generate charging estimates that include control for large-scale scenarios with millions of individua...
Preprint
Recent urbanization has coincided with the enrichment of geotagged data, such as street view and point-of-interest (POI). Region embedding enhanced by the richer data modalities has enabled researchers and city administrators to understand the built environment, socioeconomics, and the dynamics of cities better. While some efforts have been made to...
Preprint
The growing integration of distributed energy resources (DERs) in distribution grids raises various reliability issues due to DER's uncertain and complex behaviors. With a large-scale DER penetration in distribution grids, traditional outage detection methods, which rely on customers report and smart meters' last gasp signals, will have poor perfor...
Article
In future transportation systems, the charging behavior of electric Autonomous Mobility on Demand (AMoD) fleets, i.e., fleets of electric self-driving cars that service on-demand trip requests, will likely challenge power distribution networks (PDNs), causing overloads or voltage drops. In this paper, we show that these challenges can be significan...
Article
Full-text available
Climate change and economic development provide a strong rationale for urban water and electricity conservation. Although behavioral and technological factors link short-term conservation of both resources, their long-term residential consumption trends have diverged across industrialized nations: from 1990 to 2010, per capita water use decreased,...
Article
Developments in simulation and distributed control of distributed energy resources require increasingly granular characterization and modeling of load behavior. Previous work has demonstrated the viability of voltage-based power control of residential appliances to enable load flexibility without service interruption. However, conventional static a...
Preprint
Full-text available
While photovoltaic (PV) systems are installed at an unprecedented rate, reliable information on an installation level remains scarce. As a result, automatically created PV registries are a timely contribution to optimize grid planning and operations. This paper demonstrates how aerial imagery and three-dimensional building data can be combined to c...
Article
To contain the spread of the novel coronavirus (COVID-19), local and state governments in the U.S. have imposed restrictions on daily life, resulting in dramatic changes to how and where people interact, travel, socialize, and work. Using a social practice perspective, we explore how California's Shelter-in-Place (SIP) order impacted household ener...
Preprint
Electricity consumed by residential consumers counts for a significant part of global electricity consumption and utility companies can collect high-resolution load data thanks to the widely deployed advanced metering infrastructure. There has been a growing research interest toward appliance load disaggregation via nonintrusive load monitoring. As...
Article
To accelerate adoption of non-residential charging for electric vehicles, sites must maximize utilization of existing electrical infrastructure. In this study we model electric vehicle charging at a workplace using real charging data and evaluate the lifetime of the site’s transformer as the number of charging stations is incrementally increased. W...
Conference Paper
Distributed energy resources (DERs) are expected to increase the resilience of power systems to natural disasters by introducing multiple power-generation and -storage units in close proximity to users. This paper evaluates the increase in post-disaster power accessibility spurred by the rapid adoption of DERs and the potential deployment of microg...
Article
The success of time-of-use (TOU) pricing, where consumers are charged higher rates during peak usage windows, depends on consumer flexibility—an assumption that may not be true for all households or activities. We draw on concepts from social practice theory to explore the flexibility of residential electricity consumption, examining both household...
Conference Paper
Full-text available
Distributed energy resources (DERs) are expected to increase the resilience of power systems to natural disasters by introducing multiple power-generation and-storage units in close proximity to users. This paper evaluates the increase in post-disaster power accessibility spurred by the rapid adoption of DERs and the potential deployment of microgr...
Preprint
Full-text available
Understanding how efforts to limit exposure to COVID-19 have altered electricity demand provides insights not only into how dramatic restrictions shape electricity demand but also about future electricity use in a post-COVID-19 world. We develop a unified modeling framework to quantify and compare electricity usage changes in 58 countries and regio...
Article
Full-text available
One of the most groundbreaking structures in deep learning is ResNet, which utilizes skip connections to make neural networks (NNs) significantly deeper. While there are many successful applications of skip connections in computer vision (CV) and natural language processing (NLP), the applications of skip connections in electric load forecasting ar...
Article
Understanding intrinsic patterns and predicting spatiotemporal characteristics of cities require a comprehensive representation of urban neighborhoods. Existing works relied on either inter- or intra-region connectivities to generate neighborhood representations but failed to fully utilize the informative yet heterogeneous data within neighborhoods...
Article
Full-text available
Pavement condition monitoring is required to identify pavements in need of maintenance or rehabilitation. Early identification of reduction in pavement's structural resistance and improving the structural resistance by minor repairs can lead to significantly lower maintenance costs for transportation agencies. In this study, a cost‐effective wirele...
Preprint
Understanding intrinsic patterns and predicting spatiotemporal characteristics of cities require a comprehensive representation of urban neighborhoods. Existing works relied on either inter- or intra-region connectivities to generate neighborhood representations but failed to fully utilize the informative yet heterogeneous data within neighborhoods...
Article
Full-text available
There is an increasing need for monitoring and controlling uncertainties brought by distributed energy resources in distribution grids. For such goal, accurate multi-phase topology is the basis for correlating measurements in unbalanced distribution networks. Unfortunately, such topology knowledge is often unavailable due to limited investment. Als...
Article
Understanding the feasible power flow region is of central importance to power system analysis. In this paper, we propose a geometric view of the power system loadability problem. By using rectangular coordinates for complex voltages, we provide an integrated geometric understanding of active and reactive power flow equations on loadability boundar...
Conference Paper
Full-text available
Prior work has demonstrated that energy education programs designed for young children can influence the adoption of energy efficiency measures in the home. Here, we introduce the Know Your Energy Numbers (KYEN) program, an energy education program designed to teach an older audience of pre-teens, or tweens, about: (i) their energy consumption life...
Article
Full-text available
To improve the controllability and utilization of distributed energy resources (DERs), distribution-level electricity markets based on consumers’ bids and offers have been proposed. However, the transaction costs will dramatically increase with the rapid development of DERs. Therefore, in this paper, we develop an energy sharing scheme that allows...
Article
We introduce a new class of prophet inequalities-convex prophet inequalities-where a gambler observes a sequence of convex cost functions ci(xi) and is required to assign some fraction 0 ≤ xi ≤ 1 to each, such that the sum of assigned values is exactly 1. The goal of the gambler is to minimize the sum of the costs. We provide an optimal algorithm f...
Article
We introduce a new class of prophet inequalities-convex prophet inequalities-where a gambler observes a sequence of convex cost functions ci (xi ) and is required to assign some fraction 0 ≤ xi ≤ 1 to each, such that the sum of assigned values is exactly 1. The goal of the gambler is to minimize the sum of the costs. We provide an optimal algorithm...
Article
Grid topology and line parameters are essential for grid operation and planning, which may be missing or inaccurate in distribution grids. Existing data-driven approaches for recovering such information usually suffer from ignoring 1) input measurement errors and 2) possible state changes among historical measurements. While using the errors-in-var...
Preprint
Grid topology and line parameters are essential for grid operation and planning, which may be missing or inaccurate in distribution grids. Existing data-driven approaches for recovering such information usually suffer from ignoring 1) input measurement errors and 2) possible state changes among historical measurements. While using the errors-in-var...
Preprint
As essential components of the modern urban system, the health conditions of civil structures are the foundation of urban system sustainability and need to be continuously monitored. In Structural Health Monitoring (SHM), many existing works will have limited performance in the sequential damage diagnosis process because 1) the damage events needs...
Article
We developed DeepSolar, a deep learning framework analyzing satellite imagery to identify the GPS locations and sizes of solar photovoltaic panels. Leveraging its high accuracy and scalability, we constructed a comprehensive high-fidelity solar deployment database for the contiguous US. We demonstrated its value by discovering that residential sola...
Article
In this paper, we consider the problem of placing energy storage resources in a power network when all storage devices are optimally controlled to minimize system-wide costs. We propose a discrete optimization framework to accurately model heterogeneous storage capital and installation costs as these fixed costs account for the largest cost compone...
Preprint
Full-text available
We propose an emission-oriented charging scheme to evaluate the emissions of electric vehicle (EV) charging from the electricity sector at the region of Electric Reliability Council of Texas (ERCOT). We investigate both day- and night-charging scenarios combined with realistic system load demand under the emission-oriented vs direct charging scheme...
Preprint
The growing integration of distributed energy resources (DERs) in urban distribution grids raises various reliability issues due to DER's uncertain and complex behaviors. With a large-scale DER penetration, traditional outage detection methods, which rely on customers making phone calls and smart meters' "last gasp" signals, will have limited perfo...
Preprint
Full-text available
The high structural deficient rate poses serious risks to the operation of many bridges and buildings. To prevent critical damage and structural collapse, a quick structural health diagnosis tool is needed during normal operation or immediately after extreme events. In structural health monitoring (SHM), many existing works will have limited perfor...
Preprint
Distributed energy resources can enhance community resilience to power outages in the aftermath of natural disasters. We develop a method to quantify the resilience value that rooftop solar can provide to residential neighborhoods. As a case study, the method is applied to single family homes in San Carlos subjected to an earthquake based on the 19...
Preprint
There is an increasing need for monitoring and controlling uncertainties brought by distributed energy resources in distribution grids. For such goal, accurate three-phase topology is the basis for correlating and exterminating measurements in unbalanced distribution networks. Unfortunately, such topology knowledge is often unavailable due to limit...
Conference Paper
We introduce a new class of prophet inequalities-convex prophet inequalities-where a gambler observes a sequence of convex cost functions ci (xi ) and is required to assign some fraction 0 ≤ x_i ≤ 1 to each, such that the sum of assigned values is exactly 1. The goal of the gambler is to minimize the sum of the costs. We provide an optimal algorith...
Article
Residential customers are increasingly participating in demand response program for both economic savings and environmental benefits. For example, baseline estimation-based rewarding mechanism is currently being deployed to encourage customer participation. However, the deterministic baseline estimation method good for commercial users was found to...
Article
Distributed energy resources have been proposed as a promising solution to make households self-sufficient and increase power supply reliability. In this paper, we examine the reliability values of distributed solar+storage systems considering its possibility of survival during or rapid deployment after a rare weather event. To this end, we develop...
Article
This paper proposes a simple empirical scaling law that describes load forecasting accuracy at varying levels of aggregation. We show that for many forecasting methods, aggregating more customers improves the relative forecasting performance up to specific point. Beyond this point, no more improvement in relative performance can be obtained. A benc...
Article
Full-text available
A well-designed transmission cost allocation (TCA) scheme should reveal energy users’ actual usage of transmission assets. By investing in distributed energy resources (DERs), a user should be allocated with a lower transmission price if devoted to reducing transmission capacity usage. To evaluate the impacts of TCA, a co-planning framework for cen...
Article
Full-text available
As a promising distributed energy resource (DER), solar-powered heat pumps (SPHPs) can achieve significant system benefits. On the one hand, the accommodation of solar generation can be highly improved on the demand side. On the other hand, SPHPs can efficiently provide heat energy for consumers, which reduces the operational costs of central heat...
Conference Paper
Thermal-sensitive electricity usage accounts for the majority of residential electricity use worldwide. Moreover, it has substantial impacts on the power system and the society during the extreme weathers. We propose a novel data-driven method to identify the thermal-sensitive electricity usage and quantify the associated thermal sensitivity direct...
Article
For timely and effective dispatch of demand response (DR) events, utilities require an efficient customer selection process that considers multiple factors, such as customer energy consumption patterns, customer compliance, and DR event time intervals. Moreover, customer targeting strategies may be different depending on the priority of each DR pro...
Article
Full-text available
Enabling deep penetration of distributed energy resources (DERs) requires comprehensive monitoring and control of the distribution network. Increasing observability beyond the substation and extending it to the edge of the grid is required to achieve this goal. The growing availability of data from measurements from inverters, smart meters, EV char...
Article
Investment of charging facilities is facing deficit problems in many countries at the initial development stage of plug-in electric vehicles (PEVs). In this paper, we study the charging facility planning problem faced by a PEV charging station investor who aims to serve PEV customers with random behaviors and demands (but follow a series of predict...
Article
This paper presents a novel statistical model for the wavelet transform of the acceleration response of a structure based on Gaussian process theory with applications to earthquake damage detection. The proposed model considers the wavelet coefficients at each time sample as a realization of a Gaussian process that depends solely on the damage stat...
Article
An outage detection framework for power distribution networks is proposed. Given the tree structure of a distribution system, a detection method is developed combining the use of real-time power flow measurements on the edges of the tree with load forecasts at the nodes of the tree. The maximum likelihood (ML) detection decision for an arbitrary nu...
Article
Full-text available
New distributed energy resources (DER) are rapidly replacing centralized power generation due to their environmental, economic and resiliency benefits. Previous analyses of DER systems have been limited in their ability to account for socio-technical complexities, such as intermittent supply, heterogeneous demand and balance-of-system cost dynamics...
Conference Paper
Full-text available
In this paper, we address the energy storage management problem in distribution networks from the perspective of an independent energy storage manager (IESM) who aims to realize optimal energy storage sharing with multi-objective optimization, i.e., optimizing the system peak loads and the electricity purchase costs of the distribution company (Dis...
Article
Due to the volatile nature of wind and photovoltaic power, wind farms and solar stations are generally thought of as the consumers of ramping services. However, a microgrid (MG) is able to strategically integrate various distributed energy resources (DERs) to provide both energy and ancillary services (ASs) for the bulk power system. To evaluate th...