Wayne W. Weaver

Game-Theoretic Control of Small-Scale Power Systems

A power system is a collection of individual components that compete for system resources. This paper presents a game theoretic approach to the control decision process of individual sources and loads in small-scale and dc power systems. Framing the power system as a game between players facilitates the definition of individual objectives, which adds modularity and adaptability. The proposed methodology enhances the reliability and robustness of the system by avoiding the need for a central or supervisory control. It is also a way to integrate and combine supply and demand side management into a single approach. Examples are presented that use a simple nine bus dc power system to demonstrate the proposed method for various scenarios and player formulations.

Survey of multi-agent systems for microgrid control

Multi-agent systems (MAS) consist of multiple intelligent agents that interact to solve problems that may be beyond the capabilities of a single agent or system. For many years, conceptual MAS designs and architectures have been proposed for applications in power systems and power engineering. With the increasing use and modeling of distributed energy resources for microgrid applications, MAS are well suited to manage the size and complexity of these energy systems. The purpose of this paper is to survey applications of MAS in the control and operation of microgrids. The paper will review MAS concepts, architectures, develop platforms and processes, provide example applications, and discuss limitations.

Telecommunications Power Plant Damage Assessment for Hurricane Katrina– Site Survey and Follow-Up Results

This paper extends knowledge of disaster impact on the telecommunications power infrastructure by discussing the effects of Hurricane Katrina based on an on-site survey conducted in October 2005 and on public sources. It includes observations about power infrastructure damage in wire-line and wireless networks. In general, the impact on centralized network elements was more severe than on the distributed portion of the grids. The main cause of outage was lack of power due to fuel supply disruptions, flooding and security issues. This work also describes the means used to restore telecommunications services and proposes ways to improve logistics, such as coordinating portable generator set deployment among different network operators and reducing genset fuel consumption by installing permanent photovoltaic systems at sites where long electric outages are likely. One long term solution is to use of distributed generation. It also discusses the consequences on telecom power technology and practices since the storm.

Analysis and Applications of a Current-Sourced Buck Converter

In many power converter applications it is required that the topology have a current-sourced input. If a voltage step down is needed, then the choice of converter topologies is limited, or requires several stages. This paper presents a known, but rarely utilized, buck-type converter that has a current-sourced input. Analyses of the large-and small-signal models of the converter are presented with and without the use of coupled inductors. Through simulation and experimental results, the converter is shown to be a viable option for current-source applications such as active power-factor correction.

Optimal Geometric Control of Power Buffers

Modern power electronics are capable of regulating loads with bandwidths so high that they essentially enforce constant power on millisecond timescales and contribute to system-wide voltage instability problems. Active front-end control of such loads that implement a power buffer function has been shown to mitigate instability, but has relied on complicated hybrid control techniques. This paper proposes a geometric control surface that implements the power buffer function by coupling the input impedance to the stored energy and by altering the source and load dynamics. The surface is derived from optimal control theory where importance is placed on maintaining continuous input impedance and retaining as much local energy as possible. The optimal control is a tradeoff between the needs of the system and the needs of the load. This paper introduces a geometric control surface based on a change of variables that simply and effectively implements a power buffer function. The formulation and implementation of the optimal surface are presented, in addition to experimental validation of the new power buffer control law.

Dynamic Energy Resource Control of Power Electronics in Local Area Power Networks

In a local area power system, all components of the system, including sources, loads, and distribution have multiple commitments and responsibilities. These commitments include serving the energy needs of a local load, but also maintaining the efficiency and stability of the overall system. Then, the control law of a power converter should consider these objectives, but also needs to anticipate the reaction of other converters within the power network. A differential game-theoretic approach is proposed to derive sliding surfaces that uses a components objective and operating characteristics to plan an optimal state trajectory during a transient without the need for communication channels or centralized control. The optimal trajectory includes considerations for maintaining local operation of the converter, as well as the stability of the system as a whole. This paper introduces a geometric control surface based on a change of variables that simply and effectively implements a power buffer function in multiple load converters within a power network and microgrids. The formulation and implementation of the optimal surfaces are presented, in addition to experimental validation of the new power buffer control law.

Telecommunications Power Plant Damage Assessment Caused by Hurricane Katrina - Site Survey and Follow-Up Results

This paper extends knowledge of disaster impact on the telecommunications power infrastructure. It presents results both from an on-site survey conducted in October 2005 in the area affected by Hurricane Katrina and from industry and government sources. The analysis includes observations about power infrastructure damage to wire-line networks, wireless networks, transmission links, cable TV grids, and TV and radio facilities along a wide section of the U.S. Gulf Coast. In general, the impact on centralized network elements was more severe than on the distributed portion of the grids. The main cause of outage was lack of power due to fuel supply disruptions, flooding and security issues. This work also describes the means used to restore telecommunications services and proposes ways to improve logistics, such as coordinating genset deployment between different network operators and reducing genset fuel consumption by installing permanent photovoltaic systems at certain sites where long electric outages are expected

Game-Theoretic Communication Structures in Microgrids

This paper presents a game-theoretic communication structure, which is a network constructed among distributed controllers in the microgrid. This helps to share local controller information, such as control input, individual objectives among controllers, and finds a better optimized cost for the individual objectives. The modeling follows a game-theoretic framework for the energy conversion and control elements inside small-scale power systems (SSPS) or microgrids. These elements form teams to optimize performance and operation based on available information and communication. The team players are able to minimize a common objective when there is communication, and shift to the individual local objectives when communication fails. This paper also presents analysis to determine the minimal performance standards for the given level of communicated information. Then it shows optimal information mixing for team player modeling. In addition, a Stackelberg model is proposed for the microgrid with a leader-follower modeling approach. The last part of this paper shows possible examples with network contingency study with team player participation.

The load as an energy asset in a distributed architecture

As future naval ships become more electrically integrated, the ability to manage the total energy resources becomes critical. Currently these functions are available only through a centralized controller, which limits flexibility, reconfigurability, and reliability. These limitations can be avoided, and still provide system level coordination through distributed controls based on local information.

Generalized Geometric Control Manifolds of Power Converters in a DC Microgrid

In power electronics-based microgrids, the computational requirements needed to implement an optimized online control strategy can be prohibitive. This paper proposes the derivation of a geometric manifold in the energy-power domain that is based on the a-priori computation of the optimal reactions and trajectories for classes of events in a dc microgrid. The proposed states are the stored energy and power of the dc-dc converter. It is anticipated that calculating a large enough set of dissimilar transient scenarios will also span many scenarios not specifically used to develop the surface. These geometric manifolds will, then, be used as reference surfaces in any type of controller, such as a sliding mode hysteretic controller.