Projects in the labListed below are some of the projects active in the lab. They span both student and faculty research.
Minimizing Inverter Self-synchronization due to Reactive Power Injection on Weak Grids
Reactive power injection on high-impedance grids can cause oscillatory behavior as a result of “self-synchronization” of an inverter's phase detection unit (PDU). This phenomenon is particularly of concern in renewable energy applications and it occurs when the converter's injected current changes the voltage angle at the point-of-common coupling (PCC) and synchronizes to itself through its PDU. One of the most prevalent PDUs in industry is based on the synchronous-reference frame (SRF) phase-locked loop (PLL).
Reconfigurable Adaptive Network Power System (RANPS) Test-Bed for Microgrid Research
The field of naval and commercial electric power “microgrids” has advanced rapidly driven by distributed generation, power electronic converters, energy storage, computation, communication, and control. Effectively integrating and controlling a wide variety of disparate sources and loads without the presence of large rotating machines is difficult. Microgrids often use communications to control multiple sources and loads and achieve maximum performance. However, this communication may be unreliable, unknown in advance, or subject to attack. Many methods have been proposed to solve these issues, but few are tested in hardware.
A Reconfigurable Adaptive Network Power System (RANPS) test-bed is being developed to allow rapid and simple testing of the control, stability, dynamic performance, and communications of advanced microgrid power systems. The system will operate at low power (~200W elements), but have many nodes (~30) interconnected through complex electrical and communications networks. The electrical network can be arbitrarily configured into any number of AC and DC buses at different voltage levels, with line impedances, switches, and circuit breakers, and sensing. The system elements can communicate with each other over a configurable communications network of arbitrary topology and quality using Ethernet, CAN, or other protocols. Thus the system can be easily reconfigured to represent destroyers, carriers, aircraft, commercial microgrids, and small and large bases, each with their own mix of DC/AC, voltage levels, and communications.
This test-bed will be unique among other systems in existence. The system will directly further the education of future officers at the Naval Academy, and a much broader audience of students and scientists through collaboration with the Naval Postgraduate School, other ONR-funded universities conducting power research, local universities, industry, and government entities including NAVSEA Philadelphia, and Navy/Army Research Labs. As both an academic and military installation, the Academy is an ideal location for such a test bed.
Microgrid design and control for shipboard integrated power systems with dynamically interdependent engineering plant subsystems
Next generation shipboard integrated power systems must provide affordable and robust power system solutions in support of a transformation to an electric naval force. These micro-grid systems of systems are composed of dynamically interdependent engineering plant subsystems including power generation, power distribution, heating and cooling managed by multi-level control and communication networks. This research is performed in collaboration with fellow Electric Ship Research and Development Consortium (see: www.ESRDC.com) universities.
Superconducting hysteresis modeling
Type-II superconductors, including high-temperature superconductors, are characterized by the coexistence of a normal-conducting and a superconducting behavior in a mixed-state region. In this state, the superconductor is partially penetrated by quantized magnetic flux tubes or fluxoids, a phenomenon called flux pinning. Flux pinning is known to be the intrinsic reason for hysteresis.
The continuous advancement of high-temperature superconductors (HTS) technology has empowered numerous military applications. Copper coils have been traditionally used to actively reduce the magnetic signature of a naval vessel, a process called degaussing. The U.S. Navy has recently started using HTS degaussing systems, reducing the size and weight requirements by a significant margin. Press releases in the last couple of years reveal the U.S. Navy’s plan to expand the use of HTS in the fleet through power transmission, power generation, and several other applications. The proposed higher-level model provides a computationally-efficient tool capable of predicting the hysteretic magnetization of HTS, an increasingly-used technology on naval vessels.
Magnetization, magnetostriction, and stress effects
The interplay between the earth’s magnetic field, the navigation stresses, and the magnetism of a naval vessel continuously alter its magnetic signature, making it prone to detection by undersea mines. Our Preisach-type magnetic models, when coupled with FEM solvers, can predict the magnetic signature of non-trivial ferromagnetic geometries.
Nonlinear Control Method for Synchronization of Converter-Interfaced Generators (Trident Scholar Project)
Microgrids are small power systems that utilize several frequency-synchronized, low inertia, local energy resources. Microgrids that contain no high-inertia rotating machinery cannot absorb common disturbances to the balance between source generation and load consumption. Such systems are typically fitted with complex communication systems to ensure synchronization and avoid disastrous transients due to such imbalances, but new research suggests that the behavior of coupled nonlinear oscillators can be leveraged to achieve synchronization with no communication required. This project aims to assess, through simulation and testing, the feasibility and effectiveness of that control scheme.
The success of this project would promote the use of a microgrid control scheme that addresses the problem of generator synchronization without the use of a complex communication network. The benefits of such a control scheme would be to significantly decrease the complexity of microgrid power systems, make the implementation of low inertia power systems practical, and reduce the vulnerability of microgrids to cyber and electromagnetic attacks. The data collected over the course of the project would not only provide validation for this control scheme, but also serve as a practical demonstration.
Capstone: Advanced Concept Energy System - Tactical
This capstone project team won the Boeing service academy challenge in AY 2015. The Boeing sponsored service academy capstone Advanced Concept Electrical Systems – Tactical (ACES–T) design challenge was to: Conceptualize, design, develop, and fabricate a prototype of a tactical energy solution using technology that is projected to be available in the 2040 timeframe using a combination of smart grids, locally viable renewable energy, demand reduction, and systems level energy management. The solution shall be modular, scalable, operate without dependency on fossil fuels, and be highly resilient to physical and/or cyber attack through rigorous protection of energy generation and supply ensuring that the most critical needs of the tactical unit are served. Each Academy is required to simulate their system and build a prototype of critical components of their renewable energy source and/or energy management system. [From Boeing Announcement]
USNA’s winning solution came from a multi-disciplinary team of 15 midshipmen from Electrical, Mechanical, Astro, Systems and General Engineering featuring:
1. Space and terrestrial power generation
2. Innovative power and energy “bank account” management
3. DC Zonal Electric Distribution System prototype
4. Hybrid Energy Storage Module prototype
5. Wireless power transmission prototype