Ocean Sentinel Instrumentation Buoy

Ocean Sentinel Instrumentation Buoy

NNMREC has developed the Ocean Sentinel instrumentation buoy (for deployment at PMEC-NETS) to provide an electrical load and perform data acquisition for wave energy devices under test. Based on the 6-meter Navy Oceanographic Meteorological Automatic Device (NOMAD) design, the Ocean Sentinel is moored approximately 125 meters from a device under test and connected by a power and communication umbilical cable. Power generated by the device under test is processed and dissipated in a load bank onboard the Ocean Sentinel. The buoy has an initial average power rating of 100kW, with provisions to increase this in the future. Onboard switchgear and power conversion equipment provides control of the load bank. Data may be transmitted from the device under test to the instrumentation buoy via a fiber optic connection through the umbilical. Wave and current data recorded by a nearby instrument can also be transmitted to the buoy via wireless telemetry.

The Ocean Sentinel’s data acquisition system records multiple parameters:

  • Power measurements, including voltage and current
  • Environmental data, including waves, currents, winds, and temperature
  • Mooring forces, strain gauges and other signals from instrumentation onboard the test device

For grid emulation, this vessel-shaped buoy is attached to the wave energy converter by a cable. The Ocean Sentinel has an onboard resistor element, which will consume the power generated by the device, similar to the type of resistor element in electric heaters. It will also measure the amount of power generated and the characteristics of wave, wind, and currents.

Data is recorded with redundancy onboard the Ocean Sentinel and can be transmitted to shore via wireless telemetry. This wireless telemetry link also allows remote connections for control modifications and data access. The Ocean Sentinel is designed for testing devices from May through October and is available for environmental testing year round. For device testing, the system operates on a three-point mooring to hold a tight watch circle alongside the device under test, allowing connection via the power and communication umbilical. For environmental testing during the remainder of the year, the system operates on a single-point mooring to accommodate higher seas in the winter.