Hybrid Power System Intelligent Operation and Protection Involving Plug-in Electric Vehicles

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.

Hybrid power system intelligent operation and protection involving plug-in electric vehicles

Two key solutions to reduce the greenhouse gas emissions and increase the overall energy efficiency are to maximize the utilization of renewable energy resources (RERs) to generate energy for load consumption and to shift to low or zero emission plug-in electric vehicles (PEVs) for transportation. The present U.S. aging and overburdened power grid infrastructure is under a tremendous pressure to handle the issues involved in penetration of RERS and PEVs. The future power grid should be designed with for the effective utilization of distributed RERs and distributed generations to intelligently respond to varying customer demand including PEVs with high level of security, stability and reliability. This dissertation develops and verifies such a hybrid AC-DC power system. The system will operate in a distributed manner incorporating multiple components in both AC and DC styles and work in both grid-connected and islanding modes. ^ The verification was performed on a laboratory-based hybrid AC-DC power system testbed as hardware/software platform. In this system, RERs emulators together with their maximum power point tracking technology and power electronics converters were designed to test different energy harvesting algorithms. The Energy storage devices including lithium-ion batteries and ultra-capacitors were used to optimize the performance of the hybrid power system. A lithium-ion battery smart energy management system with thermal and state of charge self-balancing was proposed to protect the energy storage system. A grid connected DC PEVs parking garage emulator, with five lithium-ion batteries was also designed with the smart charging functions that can emulate the future vehicle-to-grid (V2G), vehicle-to-vehicle (V2V) and vehicle-to-house (V2H) services. This includes grid voltage and frequency regulations, spinning reserves, micro grid islanding detection and energy resource support. ^ The results show successful integration of the developed techniques for control and energy management of future hybrid AC-DC power systems with high penetration of RERs and PEVs.^

Variable Speed Limit Strategies to Reduce the Impacts of Traffic Flow Breakdown at Recurrent Freeway Bottlenecks

Variable Speed Limit (VSL) strategies identify and disseminate dynamic speed limits that are determined to be appropriate based on prevailing traffic conditions, road surface conditions, and weather conditions. This dissertation develops and evaluates a shockwave-based VSL system that uses a heuristic switching logic-based controller with specified thresholds of prevailing traffic flow conditions. The system aims to improve operations and mobility at critical bottlenecks. Before traffic breakdown occurrence, the proposed VSL’s goal is to prevent or postpone breakdown by decreasing the inflow and achieving uniform distribution in speed and flow. After breakdown occurrence, the VSL system aims to dampen traffic congestion by reducing the inflow traffic to the congested area and increasing the bottleneck capacity by deactivating the VSL at the head of the congested area. The shockwave-based VSL system pushes the VSL location upstream as the congested area propagates upstream. In addition to testing the system using infrastructure detector-based data, this dissertation investigates the use of Connected Vehicle trajectory data as input to the shockwave-based VSL system performance. Since the field Connected Vehicle data are not available, as part of this research, Vehicle-to-Infrastructure communication is modeled in the microscopic simulation to obtain individual vehicle trajectories. In this system, wavelet transform is used to analyze aggregated individual vehicles’ speed data to determine the locations of congestion. The currently recommended calibration procedures of simulation models are generally based on the capacity, volume and system-performance values and do not specifically examine traffic breakdown characteristics. However, since the proposed VSL strategies are countermeasures to the impacts of breakdown conditions, considering breakdown characteristics in the calibration procedure is important to have a reliable assessment. Several enhancements were proposed in this study to account for the breakdown characteristics at bottleneck locations in the calibration process. In this dissertation, performance of shockwave-based VSL is compared to VSL systems with different fixed VSL message sign locations utilizing the calibrated microscopic model. The results show that shockwave-based VSL outperforms fixed-location VSL systems, and it can considerably decrease the maximum back of queue and duration of breakdown while increasing the average speed during breakdown.

An after tax economic analysis of home equity conversion for the elderly

The FHA program to insure reverse mortgages has brought additional attention to the use of home equity conversion to increase income to the elderly. Using simulation, this study compares the economic consequences of the FHA reverse mortgage with two alternative conversion vehicles: sale of a remainder interest and sale-leaseback. An FHA insured plan is devised for each vehicle, structured to represent fair substitutes for the FHA mortgage. In addition, the FHA mortgage is adjusted to allow for a 4 percent annual increase in distributions to the homeowner. The viability of each plan for the homeowner, the financial institution and the FHA is investigated using different assumptions for house appreciation, tax rates, and homeowners' initial ages. For the homeowner, the return of each vehicle is compared with the choice of not employing home equity conversion. The study examines the impact of tax and accounting rules on the selection of alternatives. The study investigates the sensitivity of the FHA model to some of its assumptions.^ Although none of the vehicles is Pareato optimal, the study shows that neither the sale of a remainder interest nor the sale-leaseback is a viable alternative vehicle to the homeowner. While each of these vehicles is profitable to the financial institution, the profits are not high enough to transfer benefits to the homeowner and still be workable. The effects of tax rate, house appreciation rate, and homeowner's initial age are surprisingly small. As a general rule, none of these factors materially impact the decision of either the homeowner or the financial institution. Tax and accounting rules were found to have minimal impact on the selection of vehicles. The sensitivity analysis indicates that none of the variables studied alone is likely to materially affect the FHA's profitability. ^

Alternatives to steel grid bridge decks

Most of the moveable bridges use open grid steel decks, because these are factory assembled, light-weight, and easy to install. Open grid steel decks, however, are not as skid resistant as solid decks. Costly maintenance, high noise levels, poor riding comfort and susceptibility to vibrations are among the other disadvantages of these decks. The major objective of this research was to develop alternative deck systems which weigh no more than 25 lb/ft2, have solid riding surface, are no more than 4–5 in. thick and are able to withstand prescribed loading. Three deck systems were considered in this study: ultra-high performance concrete (UHPC) deck, aluminum deck and UHPC-fiber reinforced polymer (FRP) tube deck. UHPC deck was the first alternative system developed as a part of this project. Due to its ultra high strength, this type of concrete results in thinner sections, which helps satisfy the strict self-weight limit. A comprehensive experimental and analytical evaluation of the system was carried out to establish its suitability. Both single and multi-unit specimens with one or two spans were tested for static and dynamic loading. Finite element models were developed to predict the deck behavior. The study led to the conclusion that the UHPC bridge deck is a feasible alternative to open grid steel deck. Aluminum deck was the second alternative system studied in this project. A detailed experimental and analytical evaluation of the system was carried out. The experimental work included static and dynamic loading on the deck panels and connections. Analytical work included detailed finite element modeling. Based on the in-depth experimental and analytical evaluations, it was concluded that aluminum deck was a suitable alternative to open grid steel decks and is ready for implementation. UHPC-FRP tube deck was the third system developed in this research. Prestressed hollow core decks are commonly used, but the proposed type of steel-free deck is quite novel. Preliminary experimental evaluations of two simple-span specimens, one with uniform section and the other with tapered section were carried out. The system was shown to have good promise to replace the conventional open grid decks. Additional work, however, is needed before the system is recommended for field application.