Logic-based optimal control for shipboard power system management

The capability to dynamically reconfigure future naval integrated electric power systems is central to the Navy’s vision of the future combat ship. The objective in this thesis is to design, implement and evaluate a Shipboard Power System Management system that will prevent loss of power at critical buses when damage conditions are encountered. The approach that we are proposing is based on a new paradigm for the design of optimal control systems for hybrid systems, i.e., systems composed of continuous dynamics and discrete events. Discrete events may involve external disturbances, the discrete action of protection devices or control systems. The essence of the idea is that the discrete acting subsystems are naturally associated with a set of logical conditions or logical and the continuous system dynamics are usually described by differential equations or differential-algebraic equations. We will introduce a dynamic programming method forhybrid systems that solves dynamic optimization problems involving both binary and real variables. The stability analysis of the hybrid control systems is conducted via bifurcation control analysis. The state feedback controller strategy for the mode switching of the power system is obtained through Mixed Integer Dynamic Programming. It is computed in the form of a lookup table that represents a mapping from combinations of modes, and continuous states to the required switching actions. Simulations results will be analyzed.Ph.D., Mechanical Engineering -- Drexel University, 200

Protection and Disturbance Mitigation of Next Generation Shipboard Power Systems

Today, thanks to modern advances mainly in the power electronics field, megawatt-level electric drives and magnetic levitation are being integrated into the marine power grids. These technologies operate based on Direct Current (DC) power which require Alternating Current (AC) to DC conversion within the current grid. Medium-voltage Direct Current (MVDC) and Flywheel Energy Storage Systems (FESS) are the next state-of-the-art technologies that researchers are leaning on to produce, convert, store, and distribute power with improved power quality, reliability, and flexibility. On the other hand, with the extensive integration of high-frequency power electronic converters, system stability analysis and the true system dynamic behaviors assessment following grid disturbances have become a serious concern for system control designs and protection. This dissertation first explores emerging shipboard power distribution topologies such as MVDC networks and FESS operation with charge and discharge dynamics. Furthermore, the important topic of how these systems perform in dynamic conditions with pulsed power load, faults, arc fault and system protection are studied. Secondly, a communication-based fault detection and isolation system controller that improves upon a directional AC overcurrent relay protection system is proposed offering additional protection discrimination between faults and pulsed-power Load (PPL) in MVDC systems. The controller is designed to segregate between system dynamic short-circuit fault and bus current disturbances due to a PPL. Finally, to validate the effectiveness of the proposed protection controller, different bus current disturbances are simulated within a time-domain electromagnetic transient simulation of a shipboard power system including a PPL system operating with different ramp rate profiles, pulse widths, peak powers, and fault locations. This overarching goal of this work is to address some of the critical issues facing the US Navy as warfighter mission requirements increase exponentially and move towards advanced and sophisticated pulsed power load devices such as high energy weapon systems, high energy sensor and radar systems. The analyses and proposed solutions in this dissertation support current shipbuilding industry priorities to improve shipboard power system reliability and de-risk the integration of new power system technologies for next generation naval vessels

Derivation of Power System Module Metamodels for Early Shipboard Design Explorations

The U.S. Navy is currently challenged to develop new ship designs under compressed schedules. These ship designs must necessarily incorporate emerging technologies for high power energy conversion in order to enable smaller ship designs with a high degree of electrification and next generation electrified weapons. One way this challenge is being addressed is through development of collaborative concurrent design environment that allows for design space exploration across a wide range of implementation options. The most significant challenge is assurance of a dependable power and energy service via the shipboard Integrated Power and Energy System (IPES). The IPES is largely made up of interconnected power conversion and distribution equipment with allocated functionalities in order to meet demanding Quality of Power, Quality of Service and Survivability requirements. Feasible IPES implementations must fit within the ship hull constraints and must not violate limitations on ship displacement. This Thesis applies the theory of dependability to the use of scalable metamodels for power conversion and distribution equipment within a collaborative concurrent design environment to enable total ship set-based design outcomes that result implementable design specifications for procurement of equipment to be used in the final ship implementation

Derivation of Power System Module Metamodels for Early Shipboard Design Explorations

The U.S. Navy is currently challenged to develop new ship designs under compressed schedules. These ship designs must necessarily incorporate emerging technologies for high power energy conversion in order to enable smaller ship designs with a high degree of electrification and next generation electrified weapons. One way this challenge is being addressed is through development of collaborative concurrent design environment that allows for design space exploration across a wide range of implementation options. The most significant challenge is assurance of a dependable power and energy service via the shipboard Integrated Power and Energy System (IPES). The IPES is largely made up of interconnected power conversion and distribution equipment with allocated functionalities in order to meet demanding Quality of Power, Quality of Service and Survivability requirements. Feasible IPES implementations must fit within the ship hull constraints and must not violate limitations on ship displacement. This Thesis applies the theory of dependability to the use of scalable metamodels for power conversion and distribution equipment within a collaborative concurrent design environment to enable total ship set-based design outcomes that result implementable design specifications for procurement of equipment to be used in the final ship implementation

Design and control of harbour area smart grids with application of battery energy storage system

Global trade occurs mostly on seaborne vessels, and harbours exist as the most significant part for enabling the economic development of any country. However, the amount of fossil fuels used by conventional diesel-engine powered vessels produce a great number of types of toxic emissions, such as air pollution particles at harbours, which create a threat to human health that can contribute to higher morbidity and mortality rates among humans. Therefore, the International maritime organisation and the European Directives recommend that ships implement methods that limit toxic gas emissions and air pollution, such as using onshore power supply and fuel with low-sulphur content for on-board power generation in vessels while remaining at harbours. This research presents cutting-edge methods and tools for contributing to the development of future marine solutions and analyses of modern vessel technological requirements as well as harbour grids, and it proposes novel models of harbour area smart grids for facilitating the support of onshore power supply and charging of batteries for those vessels that require it. This research explores the usage of multiple battery-charging configurations with either slow- or fast-charging systems for electric or hybrid vessels, and it analyses the technical challenges that could inhibit or prevent the practicality of their implementation. The suitable size and allocation of battery energy storage systems for real-world case power systems of Åland Islands harbour grid are also investigated to enhance power capacity of harbour grids. Moreover, a control algorithm for the battery energy storage controller was first developed in MATLAB/Simulink for the Vaasa harbour grid, and then its performance was tested in the OPAL-RT real-time simulator by conducting a controller hardware-in-the-loop test to maintain the power balance inside the harbour grid. The proposed harbour grid models can reduce the degree of pollution that degrades the environment while providing onshore power supply and battery-charging stations for hybrid or electric vessels. Moreover, this dissertation acts as a foundation for developing future business strategies for ship owners, port administrators, and local authorities to solve similar problems as technology develops and environmental degradation continues to be a problem of every country in the world.Maailmanlaajuinen kauppa tapahtuu pääasiassa merialuksilla, ja satamista on tulossa merkittävin osa minkä tahansa maan talouskehitystä. Perinteisten dieselmoottorialusten käyttämä fossiilinen polttoaine aiheuttaa kuitenkin satamissa monenlaisia myrkyllisiä päästöjä ja ilmansaasteita, jotka ovat uhka ihmisten terveydelle ja aiheuttavat monenlaisia vaarallisia sairauksia. Tästä syystä Kansainvälinen merenkulkujärjestö IMO ja EU-direktiivit suosittelevat, että alukset käyttävät satamissa ollessaan maalta tulevaa sähkönsyöttöä tai vähärikkistä polttoainetta myrkyllisten kaasupäästöjen ja ilmansaasteiden rajoittamiseksi. Tämä tutkimus esittelee uusimpia ja tulevaisuuden merenkulun ratkaisuja, analysoi nykyaikaisten alusten teknisiä vaatimuksia sekä satamaverkkoja ja esittelee uusia malleja satama-alueen älykkäille sähköverkoille, joilla tuetaan maasähkön käyttöä ja akkujen lataamista vaativia aluksia. Tutkimuksessa tarkasteltiin useita akkuenergiavarastojen latauskonfiguraatioita sekä hitailla että nopeilla latausjärjestelmillä sähkö-/hybridialuksille ja analysoitiin niiden käytännön toteutukseen liittyviä teknisiä haasteita. Akkuenergiavarastojen sopivaa kokoa ja sijoittelua satamaverkkojen tehokapasiteetin parantamiseksi selvitettiin todelliseen verkkoon perustuvassa tapaustutkimuksessa, jossa parannettiin Ahvenanmaan verkon satamien tehokapasiteettia. Lisäksi kehitettiin akkuenergiavarastojen ohjausalgoritmi tehotasapainon ylläpitämiseksi Vaasan satamaverkossa ensin MATLAB/Simulink-mallina, jonka jälkeen sen suorituskykyä testattiin OPAL-RT reaaliaika-simulaattorilla suorittamalla ns. laitesilmukkasimulaatioita. Ehdotetuilla satamaverkkomalleilla voidaan vastata ilmansaasteista aiheutuviin ympäristöongelmiin sekä mahdollistaa maasähkönsyöttö ja akkujen latausasemat tuleville hybridi- ja sähköaluksille. Lisäksi tämä väitöskirja voi toimia pohjana uusien liiketoimintastrategioiden kehittämiselle alusten omistajien, satamajohtajien ja paikallisviranomaisten tarpeisiin.fi=vertaisarvioitu|en=peerReviewed

Design of Zonal Electrical Distribution Systems for Ships and Oil Platforms: Control Systems and Protections

Complex energy vessels such as large platforms or drillships require more efficient use of electrical power. As shipboard electrical systems become larger, problems and limits arise with the ac distribution architecture. Hybrid ac/dc onboard distribution systems are today available, which provide higher efficiency and redundancy. IEEE Std. 1662, 1709 and 1826 set technical rules and recommendations for the design of hybrid ac/dc shipboard electrical systems. Among these, zonal electrical distribution systems (ZEDS) are considered a next technological evolution, as they provide optimal power sharing (and energy storage) along with high reliability

Multiagent autonomous energy management

The objective of this thesis is to design distributed software agents for reliable operation of integrated electric power systems of modern electric warships. The automatic reconfiguration of electric shipboard power systems is an important step toward improved fight-through and self-healing capabilities of naval warships. The improvements are conceptualized by redesigning the electric power system and its controls. This research focuses on a new scheme for an energy management system in the form of distributed control/software agents. Multiagent systems provide an ideal level of abstraction for modeling complex applications where distributed and heterogeneous entities need to cooperate to achieve a common goal. The agents\u27 task is to ensure supply of the various load demands while taking into consideration system constraints and load and supply path priorities. A self-stabilizing maximum flow algorithm is investigated to allow implementation of the agents\u27 strategies and find a global solution by only considering local information and a minimum amount of communication. (Abstract shortened by UMI.)

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 324)

This bibliography lists 200 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during May, 1989. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

Challenges and potential of technology integration in modern ship management practices

This thesis explores the challenges and potential of technology integration in current ship management practices. While technology advancements were designed to be contributing to minimising task complexity, issues such as fatigue, increased administrative burden and technology assisted accidents still plague the industry. In spite of the clearly recognisable benefits of using modern technology in the management of ships, in practice its application appears lacking by a considerable margin. The main driver of the study was to appreciate the cause of this disparity. The study first reviewed a wide body of literature on issues involving the use of technology which included academic literature with empirical evidences and theoretical explanations of implementation of technology at work. With the help of the extant knowledge this research embarked on providing an explanation to the gap that existed in the application of technology in the shipping industry. By taking a case study approach the thesis looked into the induction and integration of technology in the management and operation of ships that primarily interfaced closely between the ship and its management unit on shore. Three companies with mutually diverse management setup were studied. The fourth case comprised of purposefully selected senior members of ships’ staff. The analysis of the data revealed that the manifestation of the gap in technology implementation is caused by deeper influences at work in the shipping industry. The un-optimised technology integration results in the seafarer, who is the keystone to the technology application, becoming a victim of the circumstances. The technology that was intended to ease operations and burdens ends up in controlling him, even leaving him under-resourced and causing fatigue.This was not an unintended outcome but the result of weak regulatory practices, short-term capital outlook and weakened labour practices in the shipping industry all caused by wider social and economic developments affecting not just this industry but businesses globally. The impact of such influences was however more acute in this industry resulting in such extreme consequence. By bringing to light the limited application of some fundamental principles of human-systems integration, this study has attempted to expand the boundaries of research on the subject and contributed to the holistic understanding of the various underlying factors that influence technology integration in ship management processes

A Model-Based Holistic Power Management Framework: A Study on Shipboard Power Systems for Navy Applications

The recent development of Integrated Power Systems (IPS) for shipboard application has opened the horizon to introduce new technologies that address the increasing power demand along with the associated performance specifications. Similarly, the Shipboard Power System (SPS) features system components with multiple dynamic characteristics and require stringent regulations, leveraging a challenge for an efficient system level management. The shipboard power management needs to support the survivability, reliability, autonomy, and economy as the key features for design consideration. To address these multiple issues for an increasing system load and to embrace future technologies, an autonomic power management framework is required to maintain the system level objectives. To address the lack of the efficient management scheme, a generic model-based holistic power management framework is developed for naval SPS applications. The relationship between the system parameters are introduced in the form of models to be used by the model-based predictive controller for achieving the various power management goals. An intelligent diagnostic support system is developed to support the decision making capabilities of the main framework. Naïve Bayes’ theorem is used to classify the status of SPS to help dispatch the appropriate controls. A voltage control module is developed and implemented on a real-time test bed to verify the computation time. Variants of the limited look-ahead controls (LLC) are used throughout the dissertation to support the management framework design. Additionally, the ARIMA prediction is embedded in the approach to forecast the environmental variables in the system design. The developed generic framework binds the multiple functionalities in the form of overall system modules. Finally, the dissertation develops the distributed controller using the Interaction Balance Principle to solve the interconnected subsystem optimization problem. The LLC approach is used at the local level, and the conjugate gradient method coordinates all the lower level controllers to achieve the overall optimal solution. This novel approach provides better computing performance, more flexibility in design, and improved fault handling. The case-study demonstrates the applicability of the method and compares with the centralized approach. In addition, several measures to characterize the performance of the distributed controls approach are studied