Advanced Controller Utilizing Natural Gas Engines for Microgrid Systems

With Integrated Natural Gas Engine and Storage

At a Glance

Researchers at Colorado State University have developed an advanced multivariable robust controller for a microgrid system utilizing an integrated natural gas engine and storage device (e.g., a battery). The net effect of the advanced control and integrated storage is a natural gas engine based microgrid that can operate in situations requiring significant transient performance.

Background

The controller within a microgrid is essentially a power management system and it should keep the balance between power generation and consumption to minimize the frequency deviation that results from load fluctuation and variability in renewable energy sources. When there is excess power in a grid, the grid frequency tends to increase. This applies to both utility grids and microgrids. On the other hand, the grid frequency decreases if the generated power within a grid cannot fulfill the load demands. If the utility grid frequency deviation exceeds the allowed limits, breakers will open and cause blackouts. The same principle applies to microgrids. Thus, it is critical to maintain a constant engine speed regardless of system disturbances, variations, and uncertainties.

Situations requiring significant transient performance are numerous (e.g., mining sites, fracking operations, oil & gas industry operations), and they are currently served by diesel based systems, rather than cheaper, cleaner, abundant natural gas because performance capabilities are limited with current technologies using natural gas engines under operating conditions.

Overview

Natural gas engines cannot currently operate in scenarios requiring significant transient performance, which arises from variable loads and/or variable generation of renewable (wind/solar) power. This technology facilitates the use of natural gas engines in those environments. The storage device is used to supply transient power during net load variations, and the control system manages both the engine and storage systems, and their interaction, so as to ensure:

  1. The net load is reliably delivered despite significant transient variations.
  2. The engine speed (and microgrid frequency) deviation is minimal.
  3. The battery State-of-Charge (SOC) is kept close to 50%
  4. The engine Air-Fuel-Ratio (AFR) is tightly controlled eliminating knock and misfire, while minimizing emissions.

Benefits

  • Microgrid that can operate in situations requiring significant transient performance
  • Replaces diesel fuel for cheaper, cleaner natural gas.
  • Delivers enhanced performance.
  • Tighter speed and frequency regulation.
  • Exceptional AFR control.
  • Deep energy discharge is not required.

Applications

  • Microgrids utilizing natural gas engines
  • Natural gas engine manufacturing
  • Mining sites
  • Fracking operations
  • Oil & gas industry operations
  • Other small scale microgrids
Last Updated: February 2024
Opportunity

Available for Licensing
TRL: 5

Inventors

​Yi Han
Peter Young
Daniel Zimmerle

Reference Number
15-031
Licensing Manager

Jessy McGowan
Jessy.McGowan@colostate.edu
970-491-7100