Engineering topics

Zhang, Jiucai

Publications and source records attributed to Zhang, Jiucai.

12 records

DOE OSTI2018

Value to the Grid From Managed Charging Based on California's High Renewables Study

Managed charging of electric vehicle (EV) loads has the potential to use renewable energy more effectively, shave peak demand, and fill demand valleys while serving transportation needs. However, the potential value to the grid from managed charging has not been fully quantified. This paper adopts the tools used in the National Renewable Energy Laboratory's California Low Carbon Grid Study to quantify value to the grid from managed charging by using three levels of managed loads for 13 terawatt-hours of annual load from three million EVs in a 2030 California grid scenario. Simulation results show that management of the EV fleet's aggregate load from unmanaged to 100% managed results in savings between 210 million and 660 million annually in generation system costs, depending on grid conditions. The simulation results also suggest that targeted EV supply equipment (EVSE) deployments at workplaces and other mid-day parking locations will be needed to support managed charging in a high-renewables California and enable the identified value to the grid. Although the value of generation to the grid from managed EV load paired with high renewables seems substantial, we estimate that the installed cost of an EVSE must be between 1,000 and 3,000 for a 10-year life to be cost neutral, depending on grid conditions.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2017

Enabling fast charging – A battery technology gap assessment

The battery technology literature is reviewed, with an emphasis on key elements that limit extreme fast charging. Key gaps in existing elements of the technology are presented as well as developmental needs. Among these needs are advanced models and methods to detect and prevent lithium plating; new positive-electrode materials which are less prone to stress-induced failure; better electrode designs to accommodate very rapid diffusion in and out of the electrode; measure temperature distributions during fast charge to enable/validate models; and develop thermal management and pack designs to accommodate the higher operating voltage.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2017

Enabling fast charging – Infrastructure and economic considerations

The ability to charge battery electric vehicles (BEVs) on a time scale that is on par with the time to fuel an internal combustion engine vehicle (ICEV) would remove a significant barrier to the adoption of BEVs. However, for viability, fast charging at this time scale needs to also occur at a price that is acceptable to consumers. Therefore, the cost drivers for both BEV owners and charging station providers are analyzed. In addition, key infrastructure considerations are examined, including grid stability and delivery of power, the design of fast charging stations and the design and use of electric vehicle service equipment. Each of these aspects have technical barriers that need to be addressed, and are directly linked to economic impacts to use and implementation. This discussion focuses on both the economic and infrastructure issues which exist and need to be addressed for the effective implementation of fast charging at 400 kW and above. In so doing, it has been found that there is a distinct need to effectively manage the intermittent, high power demand of fast charging, strategically plan infrastructure corridors, and to further understand the cost of operation of charging infrastructure and BEVs.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2017

Enabling fast charging – Vehicle considerations

To achieve a successful increase in the plug-in battery electric vehicle (BEV) market it is anticipated that a significant improvement in battery performance is required to improve the range that BEVs can travel. While the range that BEVs can travel on a single recharge is improving, the rate at which these vehicles can be recharged is still much slower than conventional internal combustion engine vehicles. To achieve comparable recharge times we explore the vehicle considerations of charge rates up to 350 kW. This faster recharge is expected to significantly mitigate the perceived deficiencies for long-distance transportation, to provide alternative charging in densely populated areas where overnight charging at home may not be possible, and to reduce range anxiety for travel within a city when unplanned charging maybe required. This substantial increase in the charging rate is expected to create technical issues in the design of the battery system and the vehicle electrical architecture that must be resolved. This work will focus on the battery system thermal design and total recharge time to meet the goals of implementing higher charge rates as well as the impacts of the expected increase in system voltage on the components of the vehicle.

25 ENERGY STORAGE↗

DOE OSTI2017

Enabling fast charging – Battery thermal considerations

Battery thermal barriers are reviewed with regards to extreme fast charging. Present-day thermal management systems for battery electric vehicles are inadequate in limiting the maximum temperature rise of the battery during extreme fast charging. If the battery thermal management system is not designed correctly, the temperature of the cells could reach abuse temperatures and potentially send the cells into thermal runaway. Furthermore, the cell and battery interconnect design needs to be improved to meet the lifetime expectations of the consumer. Each of these aspects is explored and addressed as well as outlining where the heat is generated in a cell, the efficiencies of power and energy cells, and what type of battery thermal management solutions are available in today’s market. Here, thermal management is not a limiting condition with regard to extreme fast charging, but many factors need to be addressed especially for future high specific energy density cells to meet U.S. Department of Energy cost and volume goals.

25 ENERGY STORAGE↗

DOE OSTI2017

Enabling fast charging – Introduction and overview

Argonne National Laboratory (Argonne), Idaho National Laboratory (INL), and the National Renewable Energy Laboratory (NREL), with guidance from VTO, initiated this study to understand the technical, cost, infrastructure, and implementation barriers associated with high rate charging up to 350 kW.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2017

Enabling Fast Charging: A Technology Gap Assessment

The transportation sector accounts for the largest percentage of energy use in the United States. Decreasing energy consumption across this sector, especially in commercial light duty transportation, is essential for the U.S. to gain energy independence. Recently, powertrain electrification with plug-in electric vehicles (PEVs) have gained traction as an alternative due to their inherent efficiency advantages compared to the traditional internal combustion engine vehicle (ICEV). Accounting for 500,000 vehicle on the road today, these PEVs will reduce oil imported into the U.S. by five billion gallons and save two billion dollars in fuel costs to consumers over their useful life. Though there are many different classes of PEV, the intent of this study is to focus on non-hybrid powertrains, or battery electric vehicles (BEVs). Despite rapid drops in cost within the BEV powertrain of over 4x in the last 10 years, the PEV market still only accounts for approximately 1% of new light duty vehicle sales annually. Though BEV powertrain costs are not quite at parity with the ICEV, another gap to wider adoption of BEVs that have been identified is the ability to refuel quickly, or to fast charge. Though the majority of recharging BEVs is done at home, having access to fast charge stations has a big impact on BEV utility from a consumer perspective. To address the fast charge barrier, charging at 350 kW, or extreme fast charging (XFC), has been proposed and will serve as the basis for discussion in this report. Studies have shown that in areas where drivers have access to 50 kW or 120 kW fast charge stations, annual electric vehicle miles traveled (eVMT) increased by over 25%, even in cases where fast charging was used for 1-5% of total charging events [1, 2]. Having access to these fast charge stations can help alleviate the “range anxiety” that is cited as a common reason for consumers to hesitate to buy a BEV. Though, to be truly competitive to the ICEV refueling experience, even higher power stations are necessary. These extreme fast charge stations (XFC) should be able to recharge a BEV in less than 10 minutes and provide approximately 175 additional miles of driving. However, this introduces a host of new challenges that need to be addressed. As a result, it is expected that packs designed to meet XFC will be significantly more expensive initially than BEVs optimized for range that can reach 140kW with current technology. From the battery cell to the power grid to which these 350 kW chargers are connected, this study will discuss the issues that need to be addressed at each level in order to implement a 350 kW charging network. Although this report is U.S.-focused, the findings should be applicable to other countries with mature automotive infrastructures.

25 ENERGY STORAGE↗

DOE OSTI2016

Stabilization of a Quadrotor With Uncertain Suspended Load Using Sliding Mode Control

The stability and trajectory control of a quadrotor carrying a suspended load with a fixed known mass has been extensively studied in recent years. However, the load mass is not always known beforehand in practical applications. This mass uncertainty brings uncertain disturbances to the quadrotor system, causing existing controllers to have a worse performance or to be collapsed. To improve the quadrotor's stability in this situation, we investigate the impacts of the uncertain load mass on the quadrotor. By comparing the simulation results of two controllers -- the proportional-derivative (PD) controller and the sliding mode controller (SMC) driven by a sliding mode disturbance of observer (SMDO), the quadrotor's performance is verified to be worse as the uncertainty increases. The simulation results also show a controller with stronger robustness against disturbances is better for practical applications.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2016

Charge Management Optimization for Future TOU Rates: Preprint

The effectiveness of future time of use (TOU) rates to enable managed charging for providing demand response depends on the vehicle's flexibility and the benefits to owners. This paper adopts opportunity, delayed, and smart charging methods to quantify these impacts, flexibilities, and benefits. Simulation results show that delayed and smart charging methods can shift most charging events to lower TOU rate periods without compromising the charged energy and individual driver mobility needs.

25 ENERGY STORAGE↗

DOE OSTI2016

Integrating PEVs with Renewables and the Grid

This presentation is an overview of NREL's Electric Vehicle Grid Integration (EVGI) efforts toward integrating Plug-in Electric Vehicles (PEVs) with renewable energy and the grid. Efforts include managed charging, local power quality, emergency backup power, and bi-directional power flow. Discussion of future vehicle-related activities under the Grid Modernization Initiative by the Multi-Lab EV Smart Grid Working Group.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2016

Charge Management Optimization for Future TOU Rates

25 ENERGY STORAGE↗

DOE OSTI2016

EV-Grid Integration (EVGI) Control and System Implementation - Research Overview

Plug-in electric vehicles (PEVs) are being increasingly adopted in industry today. Microgrid applications of PEVs require the development of charging and discharging algorithms and individual characterization of vehicles including the on-board chargers and vehicle mobility. This study summarizes the capabilities of the Electric Vehicle Grid Integration (EVGI) Team at NREL and underlines different recent projects of the Team. Our studies include V1G, V2G, and V2H control of PEVs as well as test and analysis of stationary and dynamic wireless power transfer (WPT) systems. The presentation also includes the future scope of study which implements real-time simulation of PEVs in a microgrid scenario. The capabilities at Vehicle Testing and Integration Facility (VTIF) and Energy Systems Integration Facility (ESIF) were described within the scope of the EVGI research.

33 ADVANCED PROPULSION SYSTEMS↗