Ecosense Sustainable Solutions has successfully delivered and deployed an advanced Ocean Wave Simulator to KIIT University, Bhubaneswar. This one of a kind setup enables hardware in loop emulation of an Oscillating Water Column (OWC) based ocean energy power plant using a Permanent Magnet Synchronous Generator (PMSG) and irregular wave models.
Ocean energy is a promising renewable energy resource, offering advantages such as greater predictability compared to wind. However, it also presents challenges like large and slow amplitude variations in power output. Ecosense has developed a hardware in loop prototype to study electric power profiles from OWC based wave power plants. The system facilitates research into solutions for improving the intermittency of grid-fed power and tests OWC behavior under conditions like voltage dips. It uses statistical models based on real ocean wave data to provide realistic simulations.
Among various wave energy conversion systems, those based on the Oscillating Water Column (OWC) principle are closest to industrial application. In an OWC system, the wave-induced pressure changes push air in and out of a chamber, driving an air turbine connected to a generator. Despite the alternating air flow, most PTO (Power Take Off) systems like the Wells turbine maintain continuous rotational direction. Facilities based on this principle exist globally, such as the Mutriku power plant in Spain, which operates with 16 chambers and turbines.
A) Irregular Wave Model:
The sea surface is characterized by a frequency spectrum, derived from real
wave measurements. This allows reproduction of realistic sea states in the time
domain. The system implements several spectral models—Pierson–Moskowitz,
JONSWAP, TMA, and Bretschneider—executed in real-time using an FPGA board (Sb
RIO 9607). A higher number of harmonics increase realism but also processing
time.
B) Chamber Model:
A simplified model considers the air column as incompressible, and wave height
is equal to water surface elevation inside the chamber. This simplification
helps decouple the OWC and PTO systems, maintaining the wave’s multifrequency
nature in power generation. A pressure relief valve keeps the turbine torque
coefficient within the stable range before stalling.
C) Turbine Model:
A Wells turbine is modeled using the torque coefficient as a function of the
flow coefficient. The torque derived from this model is reproduced in real time
using a controlled DC motor. Efficiency drops sharply beyond the stall point,
as shown in the characteristic curves integrated into the prototype.
The electrical side uses a Permanent
Magnet Synchronous Generator (PMSG) driven by the motor. The power output
passes through:
This configuration is
widely used in small PMSG-based wind turbines and allows independent control of
active and reactive power. The generator torque is regulated via current
control in the chopper. A space vector modulator (SVM) with Park transformation
and PLL is used to synchronize and control inverter output to the grid. The
control architecture includes nested loops for dc bus voltage and reactive
power regulation.
Control and visualization
are managed through LabVIEW. The user interface enables selection of
wave spectra (Pierson–Moskowitz, Bretschneider, JONSWAP) and configuration of
energy parameters. Each simulation generates unique waveforms with the same
energy content by assigning random phases to harmonic components.
The Ecosense-developed
Ocean Wave Simulator is a comprehensive hardware in loop platform that
realistically emulates an Oscillating Water Column energy plant. With irregular
wave profile modeling, simplified but accurate chamber and turbine models, and
a fully functional electric power generation system, the prototype enables
extensive academic and research studies. It supports validation of control
strategies, inverter behavior, and fault ride-through capabilities under
simulated ocean conditions. By deploying this system at KIIT University,
Ecosense continues its mission of supporting advanced renewable energy research
in India.