Water cycle algorithm–based airflow control for oscillating water column–based wave energy converters

Abstract

The stalling behavior is a feature of the Wells turbine that limits the generated output power of power plants using this turbine. The NEREIDA wave power plant installed in the harbor of Mutriku in the northern Spanish shoreline constitutes an excellent example of this phenomenon. This article deals with the modeling, simulation and control of an oscillating water column unit within the NEREIDA wave power plant. The stalling behavior is investigated and two control strategies are proposed to avoid it. The first control approach is the airflow control which aims to adjust the airflow in the turbine duct using a proportional–integral–derivative controller tuned with the water cycle algorithm. The second control approach is the rotational speed control adjusting the rotor speed using the rotor-side converter of the back-to-back converter which is wired to the doubly fed induction generator. Results of comparative studies show a power generation improvement even relative to the real measured data.

Self-Adaptive Global-Best Harmony Search Algorithm-Based Airflow Control of a Wells-Turbine-Based Oscillating-Water Column

“…Tuning the PID controller in a complex system such as the OWC often is hard and tedious when using conventional methods and lacking an appropriate systematic design approach. In order to tune the PID controller, the use of optimization theory has been suggested as a promising recourse to easily calculate and optimize all PID gains [21,22].…”

“…PID controller tuning is a delicate and complex task when lacking a systematic approach. To solve the problem design of PID controllers, the optimization theory has been proven to be an effective method to tune and optimize the controller parameters [21,22]. Numerous optimization algorithms were investigated and tested with the PID controller in different applications, for instance, the Particle Swarm Optimization (PSO) [23,24], the Water Cycle Algorithm (WCA) [21,24], and the Harmony Search Algorithm (HSA) [22,24].…”

ANN-Based Airflow Control for an Oscillating Water Column Using Surface Elevation Measurements

“…where V c , w c , and l c are the capture chamber's volume, inner width, and length, respectively. From Equation (3), the volume flow rate may be described as [48][49][50]:…”

“…with c = w c /k. By using Equation (4) and taking into consideration the topology of the capture chamber, the axial airflow speed may be defined as [48][49][50]:…”

“…The stalling phenomenon of the Wells turbine may be avoided by continuously adjusting the flow coefficient [48,49]. By referring to Equation (7), the flow coefficient depends on the airflow speed in the turbine duct.…”