MULTIDIMENSIONAL OPTIMAL DROOP CONTROL FOR WIND RESOURCES IN DC MICROGRIDS

Two important and upcoming technologies, microgrids and electricity generation from wind resources, are increasingly being combined. Various control strategies can be implemented, and droop control provides a simple option without requiring communication between microgrid components. Eliminating the single source of potential failure around the communication system is especially important in remote, islanded microgrids, which are considered in this work. However, traditional droop control does not allow the microgrid to utilize much of the power available from the wind. This dissertation presents a novel droop control strategy, which implements a droop surface in higher dimension than the traditional strategy. The droop control relationship then depends on two variables: the dc microgrid bus voltage, and the wind speed at the current time. An approach for optimizing this droop control surface in order to meet a given objective, for example utilizing all of the power available from a wind resource, is proposed and demonstrated. Various cases are used to test the proposed optimal high dimension droop control method, and demonstrate its function. First, the use of linear multidimensional droop control without optimization is demonstrated through simulation. Next, an optimal high dimension droop control surface is implemented with a simple dc microgrid containing two sources and one load. Various cases for changing load and wind speed are investigated using simulation and hardware-in-the-loop techniques. Optimal multidimensional droop control is demonstrated with a wind resource in a full dc microgrid example, containing an energy storage device as well as multiple sources and loads. Finally, the optimal high dimension droop control method is applied with a solar resource, and using a load model developed for a military patrol base application. The operation of the proposed control is again investigated using simulation and hardware-in-the-loop techniques

Multidimensional optimal droop control for DC microgrids in military applications

Reliability is a key consideration when microgrid technology is implemented in military applications. Droop control provides a simple option without requiring communication between microgrid components, increasing the control system reliability. However, traditional droop control does not allow the microgrid to utilize much of the power available from a solar resource. This paper applies an optimal multidimensional droop control strategy for a solar resource connected in a microgrid at a military patrol base. Simulation and hardware-in-the-loop experiments of a sample microgrid show that much more power from the solar resource can be utilized, while maintaining the system’s bus voltage around a nominal value, and still avoiding the need for communication between the various components

Multidimensional Optimal Droop Control for DC Microgrids in Military Applications

Reliability is a key consideration when microgrid technology is implemented in military applications. Droop control provides a simple option without requiring communication between microgrid components, increasing the control system reliability. However, traditional droop control does not allow the microgrid to utilize much of the power available from a solar resource. This paper applies an optimal multidimensional droop control strategy for a solar resource connected in a microgrid at a military patrol base. Simulation and hardware-in-the-loop experiments of a sample microgrid show that much more power from the solar resource can be utilized, while maintaining the system’s bus voltage around a nominal value, and still avoiding the need for communication between the various components

Optimal geometric control of Dc microgrids

Droop control is a common method used in power systems to share load between multiple sources. In a dc system, traditional droop control utilizes a linear relationship to determine the reference current for each source based on the changing bus voltage. This paper presents a method for finding a nonlinear droop relationship in order to optimize the source operation to meet a given objective. The method is implemented for an example dc microgrid system. Simulation and hardware-in-the-loop (HIL) results are presented

Multidimensional droop control for wind resources in dc microgrids

Two important and upcoming technologies, wind resources and microgrids, are increasingly being combined.Various control strategies can be implemented, and droop control provides a simple option without requiring communication between microgrid components. However, traditional droop control does not allow the microgrid to maximise the power available from the wind. This study proposes a novel droop control strategy, which implements a droop surface in higher dimension than the traditional strategy. Simulation results show that power from the wind can be maximised, while maintaining the system\u27s bus voltage around a nominal value using a distributed multidimensional droop approach. Selection of the optimal droop relationship is discussed and simulation results are presented

Optimization of grid-connected wind and battery energy storage system

This paper implements optimal control strategies in the scenario of a battery energy storage system connected to the electric grid together with a wind turbine. A simplified model for a battery is first developed, along with a state equation model of the system. Optimal control is used to minimize the difference between the actual battery power and the given reference power. The battery is connected to the grid through a buck converter, and the optimal control solution is used to calculate the necessary duty cycle to achieve the desired results. Inequality constraints are added to ensure that the simulation is a realistic model of the behavior of a battery. The control strategy is also demonstrated experimentally with a battery and sample grid system

Optimal Multidimensional Droop Control for Wind Resources in DC Microgrids

The inclusion of electricity generation from wind in microgrids presents an important opportunity in modern electric power systems. Various control strategies can be pursued for wind resources connected in microgrids, and droop control is a promising option since communication between microgrid components is not required. Traditional droop control does have the drawback of not allowing much or all of the available wind power to be utilized in the microgrid. This paper presents a novel droop control strategy, modifying the traditional approach and building an optimal droop surface at a higher dimension. A method for determining the optimal droop control surface in multiple dimensions to meet a given objective is presented. Simulation and hardware-in-the-loop experiments of a sample microgrid show that much more wind power can be utilized, while maintaining the system’s bus voltage and still avoiding the need for communication between the various components

Microgrid frequency regulation using wind turbine controls

This paper proposes a control system that uses wind energy to regulate the frequency of an islanded microgrid. The model used in both computer and hardware simulation includes a scaled representation of a microgrid that uses a permanent magnet AC (PMAC) machine and a variable resistance load. The wind turbine is represented by a DC machine as the prime mover connected with a PMAC generator. As the microgrid load changes the frequency of the system changes and the proposed control system regulates power from the wind turbine as necessary to correct the frequency and maintain a nominal value. Results of both computer simulation and hardware implementation show that wind energy can be used to maintain microgrid frequency in islanded operation. © 2014 IEEE

Multidimensional Optimal Droop Control for DC Microgrids in Military Applications

Reliability is a key consideration when microgrid technology is implemented in military applications. Droop control provides a simple option without requiring communication between microgrid components, increasing the control system reliability. However, traditional droop control does not allow the microgrid to utilize much of the power available from a solar resource. This paper applies an optimal multidimensional droop control strategy for a solar resource connected in a microgrid at a military patrol base. Simulation and hardware-in-the-loop experiments of a sample microgrid show that much more power from the solar resource can be utilized, while maintaining the system’s bus voltage around a nominal value, and still avoiding the need for communication between the various components

Perceptions and influencers affecting engineering and computer science student persistence

In the 2012-2013 academic year, a survey to investigate why engineering and computer science students persist in their major was conducted at Michigan Technological University. This paper discusses the results of the survey and ties the findings to the literature. It focuses on: (1) who influenced students\u27 decisions on picking a major or on changing a major (for example, friends, family, academic advisors, faculty, upper-division or graduate students, co-workers, and supervisors), and how did they affect students\u27 persistence and (2) what is the impact of role models on student persistence. The analysis compares students who reported not having considered changing majors to students who considered switching to another major. The findings show that the students who did not consider changing majors reported having a stronger support system including faculty, academic advisors, and engineers who serve as role models. The data suggest that university faculty and staff need to reach out to the students who are deliberating about their initial choice of major and support the decision making process. © 2013 IEEE