Making Small Wave Energy Converters Cost-Effective for Underwater Microgrids through a 10-Fold Improvement in Year-Round Productivity

South Dakota School of Mines and Technology

Objective

Proposed Work
Drivetrain and Actuator
1- Conceptual Design of actuators with large stroke and large rated force.
2- Conceptual Design of a high efficient drivetrain and energy storage for low frequency oscillatory systems (WECs)
3- Evaluate several technologies (electrical, mechanical, and hydraulic) for the design of the actuator and powertrain, with the requirement of limiting the overall cost.

Investigators: Ossama Abdelkhalik and Mark Vaughn

Advanced Controls in Wave Eergy Conversion

Sandia National Labs

Wave energy converter (WEC) control analysis and development within the Water Power Technologies department at Sandia National Laboratory. Design an advanced control strategy for WEC and ongoing research focused on the development and analysis of novel control strategies for WECs.

Investigator: Ossama Abdelkhalik

Autonomous Microgrids: Theory, Control, Flexibility and Scalability

U.S. Dept of Defense Office of Naval Research

Project Description and Research Objectives:
From large scale electric power grids and microgrids down to small scale electronics, power networks are typically deployed using a fixed infrastructure architecture that cannot expand or contract without significant human intervention. Mobile, monolithic power systems exist but are also not readily scalable to exploit surrounding power sources and storage devices. However, if a power network is constructed from physically independent and autonomous building blocks, then it would be infinitely reconfigurable and adaptable to changing needs and environments. The aim of this project is to integrate vehicle robotics with intelligent power electronics to create self-organizing, ad-hoc, hybrid AC/DC microgrids. The main benefits of this system would be the establishment and operation of an electrical power networks independent of human interaction and can adapt to changing environments, resource and mission. In the context of U.S. Naval platforms, this autonomous electrical network could be used in land, air or sea systems.

The focus of this work will be on land based autonomous microgrid systems, but the fundamental theory developed may be applicable to air and sea based systems as well. Investigators at Michigan Technological University have developed initial hardware and testbeds to study this problem. However, a more detailed theoretical foundation is needed to be developed to apply autonomous microgrids to a wide variety of operational scenarios with various resources. It is also hypothesized that given the flexibility of this approach that it could be equally applied over a vast scale of energy assets. A microgrid that grows in situ from 10 s to 100 s to 1000 s of energy assets can be equally managed, controlled and optimized through the highly scalable approach proposed in this project.

These applications are examples of the critical need for autonomous mobile microgrid capable of operating in highly dynamic and potentially hazardous environments. Our overall goal is to create a scalable architecture to develop a system that accounts for uncertainty in predictions and disturbances, is redundant, requires minimal communication between agents, provides real-time guarantees on the performance of path planning, and reaches the targets while making electrical connections. Such architecture provide a coherent layout for the interconnection between different disciplines on this topic and minimizes the integration concerns for future developments.

Description of the Proposed Work:
• Microgrid Planning and Control
• Microgrid Topology and Optimization
• Electrical Components and Power Flow
• Game-Theoretic Control
• Physical Autonomous Positioning and Connections

Investigator: Wayne Weaver, Rush Robinett and Nina Mahmoudian

On Integrating New Capability into Coastal Energy Conversion Systems

National Science Foundation -South Dakota School of Mines & Technology

Overview:
Analyze and simulate the power capture from arrays of wave energy converters (WECs) with and without the presence of an object. Nonlinear WECs will be analyzed and exploited for more energy capture. For object detection, MTU will develop an estimator. In addition to having a model that detects the presence of an object, the estimator will use that model and account for uncertainties that we have in the model and also measurement errors; in any case we need to know statistical characteristics about these uncertainties and errors. MTU will participate in the WEC array overall design, analysis, modeling and simulations; control design for Design 2, nonlinear modeling and control, and topology optimization.

Investigator: Ossama Abdelkhalik and Mark Vaughn

Distributed and Decentralized Control of Aircraft Energy Systems

U.S. Dept of Defense, Air Force Research Lab -InfoSciTex Corp (AFRL)

Aircraft energy system components, including sources, loads and distribution, have multiple commitments and responsibilities. Often much of the system is comprised of power electronic converters for sources, loads, and energy storage (chemical, mechanical and thermal). For example, a point of load power converter has the commitment to serve the energy needs of the end load. However, if the power system collapses, the needs of the load cannot be met. Therefore, it is also in the interest of the conve1ter to contribute to the global stability of the power system by reducing nonlinear dynamics and incremental negative impedance. One method to mitigate the destabilizing effects of constant power loads is the power buffer concept. A power buffer is a device that mitigates a destabilizing event by presenting controlled impedance to the supply during the transient while local energy is used to maintain constant power to the load until the system can recover. A power buffer may include additional hardware, or may merely be a modification of the controls of an existing active front end power converter. However to date the use of a load as an energy asset in a power buffer has been limited to traditional chemical (capacitor and battery) storage devices in the electrical network. Next generation aircraft may have a broad range of potential assets in the form of loads, including inertial spinning devices and thermal systems, which could be utilized in the overall energy strategy.

Research with AFRL researchers to investigate distributed and decentralized control of aircraft energy systems. This effort will include using models and simulations to formulate decentralized control and study the effects. Specifically,
• Develop and document a mathematical model of the aircraft energy systems including thermal and inertial loads.
• Formulate a decentralized power buffer control including inertial and thermal loads as energy storage assets.
• Develop and document nume1ic simulation models in MATLAB/Simulink and/or
• Modelica. The models will include aircraft system and controls.
• Validate theoretic results through simulation under stressing scenarios.

Investigator: Wayne Weaver

Unstable and Pulse Load Control Designs for Naval Electrical Systems

Sandia National Labs

NAVSEA
Using the HSSPFC (Hamiltonian Surface Shaping and Power Flow Control) derived Matlab/Simulink tools develop a Reduced Order Model (ROM) to support control designs for pulse load applications for i) up to (3) key ship modes of a ship power system operation and ii) a stable and unstable modes of switching operations as a part of a survivability scenario.

ElectroMagnetic (EM) Coupling-Penetration Measurement Standard
Testing and simulation facilities have various methods for test readiness activities and post-test instrumentation and sensors performance verification. Such a canonical standard has been developed but has not been used or re-verified in recent years. Using the mathematical model of the canonical measurement standard previously documented in an EM Sand report, verify both analytical and computational analyses and propose experimental validation with analytical model.

Investigator: Wayne Weaver

Toward Undersea Persistence

Office of Naval Research

The current challenge impeding advances in the U.S. Navy’s mobility is significant interruptions during undersea missions. Missions such as studying arctic physical environments; understanding the effects of sound on marine mammals; submarine detection and classification; and mine detection and neutralization in both the ocean and littoral environment require persistent operation of unmanned systems in challenging and dynamic environments. The proposed work will create an architecture that integrates three elements of energy, communication, and docking to guarantee undersea persistence where limited power resources and unknown environmental dynamics pose major constraints. The architecture will take into account: the number of operational AUVs required for different operation periods, recharging specifications, communication and localization means, and environmental variables.

The overall goal of this project is: to develop a mobile power delivery system that lowers deployment and operating costs while simultaneously increasing network efficiency and response in dynamic and often dangerous physical conditions. The aim is to create network optimization and formation strategies that will enable a mobile power deliver system to meet overall mission specifications by: 1) reconfiguring itself depending on the number of operational AUVs and; 2) responding to energy consumption needs of the network, situational condition, and environmental variables. The outcome of this work will be a theoretical, computational, and experimental roadmap for building and implementing an autonomous distributed system with mobile power delivery and onsite recharging capability. This roadmap will address fundamental hardware and network science challenges. The long-term outcome of this work will be a persistent and stealthy large area presence of AUV fleets able to perform undersea Navy missions by accurately and autonomously responding to energy needs, situational dynamics and environmental variables.

Investigator: Nina Mahmoudian

“CRISP Type 2: Revolution through Evolution: A Controls Approach to Improve How Society Interacts with Electricity.”

National Science Foundation

This CRISP project addresses the challenges associated with the rapid evolution of the electricity grid to a highly distributed infrastructure. The keystone of this research is the transformation of power distribution feeders, from relatively passive channels for delivering electricity to customers, to distribution microgrids, entities that actively manage local production, storage and use of electricity, with participation from individual customers. Distribution microgrids combine the advantages of the traditional electricity grid with the advantages of emerging distributed technologies, including the ability to produce and use power locally in the event of grid outages. The project will result in a unified model that incorporates key aspects of power generation and delivery, information flow, market design and human behavior. The model predictions can be used by policymakers to guide a transition to clean energy via distribution microgrids. The expectation is to enable at least 50% of electric power to come from renewable resources. This cannot be done with either the traditional grid, due to its limited capacity to accommodate intermittent renewable power sources, or with fully decentralized approaches, which would not be affordable for most utility customers.

This project addresses many socio-technological gaps necessary to translate from research discovery to commercial applications. To date, there is no theoretical framework to ensure system stability as renewable energy routed through power electronics replaces traditional rotating machinery. To achieve an optimal mix of storage performance and information bandwidth and to design nonlinear controllers, we will use Hamiltonian Surface Shaping Power Flow Control theory. We will study methods to detect malicious tampering with information flows. The complex interaction of intermittent resources, human behavior and market structures will be modeled in an agent-based simulation. System inputs will be provided by utility and meteorological data, and by behavioral models that incorporate information obtained by surveys, interviews and metering data. Emergent system dynamics will be abstracted and studied using dynamical complex network theory, to explore stability limits as a function of human behavior and market design. Finally, the effect of enhanced controllability of distribution systems on the robustness of large energy-information-social networks will be analyzed using interdependent Markov-chain models. Graduate students involved in this program will be exposed to a unique combination of skills from engineering, data analysis and social sciences; such cross-disciplinary training will prepare them for leadership roles in the emerging energy economy of tomorrow.

Investigators: Laura Brown, Chee-Wooi Ten, Wayne Weaver

Advanced Control of Wave Energy Converters

Sandia National Laboratory

Background
A new multi-year effort has been launched by the Department of Energy to validate the extent to which control strategies can increase the power produced by resonant Wave Energy Converters (WEC) devices. A large number of theoretical studies have shown promising results in the additional energy that can be captured through control of the power conversion chains of resonant WEC devices.
However, most of the previous work has been completed on highly idealized systems and there is little to no validation work. This program will specifically target controls development for nonlinear, multi-degree of freedom WEC devices. Multiple control strategies will be developed and the efficacy of the strategies will be compared within the “metric matrix.”
Objective: The purpose of this contract is to provide the labor to develop and implement custom control strategies for a specified WEC device.

Scope of Work
Michigan Technological University (MTU) will provide optimization expertise (Dynamic Programing, pseudo-spectral, shape optimization, others) to support MTPA-FF (mid-targeting phase and amplitude-feedforward) designs and analysis specific to the performance model WEC. This will include numerical simulations specific to the metric matrix requirements. In addition, MTU will provide expertise and support for feedforward real-time implementation and investigations.

Investigator: Ossama Abdelkhalik