Current Projects

Research focuses on design, development, evaluation, control, and standardization of grid-connected power electronic equipment on both the supply and load side of power systems. Specific GRAPES projects are selected by the GRAPES members at the semi-annual meetings. The GRAPES Center currently has eleven active projects:

Project Number Project Title Principal Investigator
Project GR-10-01 Power Packaging Simon S. Ang (UA)

    Objectives

  • Identify current packaging technologies and barriers associated with high voltage device and module packaging for both silicon and silicon carbide power devices.
  • Develop packaging structures, materials, and characteristics for power module packaging of devices with ratings above 10 kV.
  • Identify the high temperature potential and operating reliability for the packaging components.
  • Intelligent power modules combining power electronics with control circuits.
Project GR-10-02 Green Power Node Roger A. Dougal (USC), Alan Mantooth (UA)

    Objectives

  • Provide general-purpose node to integrate DC and AC power and load resources in residential power systems.
  • Provide standardized grid-side connection, with objective to make the system dispatchable from the grid side and uninterruptable on the customer side.
  • Universal and bidirectional power ports on DC side, connect to a variety of power resources.
  • Network data interface for local and grid-area data access.
  • Extend the value of grid-connected PV by providing backup power capability to the customer.
Project GR-10-03 Transmission Load Flow Roy McCann (UA), Enrico Santi (USC)

Objectives

This project is a collaborative UA/USC effort on power system state-estimation and power flow control: Development at USC uses a power converter to make wideband three-phase impedance measurements at its interface to the power grid . This provides knowledge of harmonic and high-frequency impedances in order to predict harmonic propagation and voltage distortion at various locations on the power network, to identify harmonic polluters and to predict resonances. The UA portion investigates localized power control acting at the distribution level through coordination of power electronic systems with the objective of influencing power flows across the transmission grid. Using the impedance information developed at USC, optimization to thermal and stability limits of the existing transmission line and generation infrastructure is achieved through coordination of distribution level power electronic equipment.

Related UA Research: Fault Current Limiter

To develop a high power density, fast acting solid-state fault current limiter. Advantages Increased overall system reliability for distribution and transmission systems

Project GR-10-05 ESS for Diesel Microgrid Juan Balda (UA)

Objectives

Integration of a diesel generator and a battery energy storage system (BESS) within a microgrid environment. Diesel generator at customer facility used for peak shaving and emergency power. Microgrid draws a small amount of power when peak shaving but can island from grid. Voltage on the microgrid can be regulated by coordinating the diesel generator and BESS.

Project GR-10-06 Power Quality Yong-June Shin (USC)

    Objectives

  • Resolve power quality problems of the grid-connected wind turbine generators (WTG)
  • Modeling of WTGs Modeling of Power Electronic Elements
  • Modeling of SVC/STATCOM Power Quality Analysis of Wind Farms Collaboration with GRAPES IAB members - AEP (American Electric Power) and SPP (Southwest Power Pool)
Project GR-10-07 GaN Power Converters Alan Mantooth (UA), Enrico Santi (USC)

    Objectives

  • Develop High-bandwidth, high-temperature isolated control for switching cells at arbitrary potentials in order to be able to capitalize on high-voltage, high switching frequency and high temperature operation of wide bandgap power devices for grid applications
  • Advance the state of the art in fully-integrated, fully-wide-bandgap, fully-isolated power electronics converters based on GaN and SiC
  • Produce new state-of-the-art boundaries in switching speeds, volumetric reduction, power density, temperature of operation, efficiency, and immunity to interference
Project GR-10-09 Assessment of Rapid Voltage Collapse Charles W. Brice (USC), Yong-June Shin (USC)

Objectives

Transmission-level power system studies invariably include power-flow analysis for the purposes of ensuring line and transformer ratings are adequate and to assess the probability of voltage collapse. These power-flow studies are used in transmission planning and in operation of the bulk power system (on-line power flow). Load models are essential, especially if the study concerns voltage collapse. Increasing power electronic front ends (e.g., motor drives) with high control bandwidths may make existing load models inadequate, decreasing situational awareness for operators. Furthermore, the modern grid with renewable power generation increases complexity for real-time monitoring of power- flow.This project utilizes time-synchronized magnitude and frequency of voltage in wide area acquired by Phasor measurement units (PMUs) and this project investigates development of advanced signal processing techniques that provide an accurate time-varying load models for detection and prevention of voltage collapse.

Project GR-10-10 Flexible Research Control Platform for Grid-connected Converters Herb Ginn (USC)

Objectives

Develop a digital control system for power electronics that interfaces with Power Electronic Building Block (PEBB) type converter power stages in order to provide a flexible and reconfigurable platform for grid-connected converter control development. In addition, a hardware-in-the-loop interface will be included in the digital controller in order to allow maximum flexibility for laboratory setups. For example, a set of converters in a back-to-back configuration could be utilized to mimic an energy source such as a PV array or wind turbine system.

Project GR-10-11 Power Module Layout Synthesis Tool Alan Mantooth (UA), Juan Balda (UA)

Objectives

A multi-year project into the design and implementation of a CAD tool that is used to analyze and optimize the simultaneous electrical, mechanical and thermal issues involved in power module design. This project will focus on the development of algorithms for thermal model abstraction, constrained optimization at the lumped-element level of representation, and layout synthesis of power modules accounting for the electrical parasitic, thermal management issues and mechanical constraints imposed by common substrate materials.

As power electronics become more ubiquitous, it is clear that one bottleneck to realization is the ability to design the module to handle parasitic, heat loads and stresses. This tool will be useful in a huge variety of contexts in power module design and such a capability does not exist today! Design productivity will be enhanced by at least an order of magnitude.

Project GR-11-01 Flexible Research Control Platform Herbert L. Ginn (USC)

Objectives

This project will develop a digital control system for power electronics that interfaces with Power Electronic Building Block (PEBB) type converter power stages in order to provide a flexible and reconfigurable platform for grid-connected converter control development. In addition, a hardware-in-the-loop interface will be included in the digital controller in order to allow maximum flexibility for laboratory setups. For example, a set of converters in a back-to-back configuration could be utilized to mimic an energy source such as a PV array or wind turbine system.

A control development kit will be provided that will generate code for the digital control system using a graphical user interface. Common blocks for controls used in grid-connected converter applications will be provided.

Project GR-11-03 Power-Dense Power Electronic Interfaces for Renewable Energy Sources Juan Balda (UA)

Objectives

Several renewable energy sources produce sinusoidal voltages at frequencies which are different from the grid frequency, or produce dc voltages which are not compatible with the grid voltage. Examples of the former are wind turbines using PMSG, or microturbines in (mini) CHP applications. Examples of the later are utility-scale converters for solar farms. Most existing topologies use electrolytic capacitors which are well known to represent the weakest link in power converters. Thus, there is a need for power dense and reliable power electronic interfaces for connecting renewable energy sources. The unidirectional matrix converters (UMC) have volume advantages with little efficiency penalties over standard back-to-back power converters. The main objective of this project is to develop unidirectional matrix converters which are reliable and power dense to interconnect renewable energy sources which require ac/ac conversion, or dc/ac conversion with a high-frequency stage. The absence of electrolytic capacitors is an advantage but is also a disadvantage if it is required to exchange reactive power with the grid. Hence, the viability of adding energy storage to the UMC topology will be investigated. Lastly, wideband gap semiconductor devices like SiC and GaN devices will be considered to increase the system efficiency.