Tidal Power Unit Research Articles

A Novel Deep Reinforcement Learning Controller Based Type-II Fuzzy System: Frequency Regulation in Microgrids

The high-penetration of distributed generation technologies in the form of MicroGrids (MGs), in recent years, has increased the risk of frequency instability since their energy is supplied by renewable energy resources (RESs) with uncertain nature. Under such circumstances, providing an MG model with an efficient load frequency control (LFC) has a fundamental role in restoring the stability of the unstructured power system. In this study, a hybrid power system with the application of the Tidal Power Unit (TPU) and Vehicle-to-Grid (V2G) is effectively planed as an isolated MG. A new fractional gradient descent (FGD) based on a single-input interval type-2 fuzzy logic controller (SIT2-FLC) is suggested as the main LFC controller, where the footprint of uncertainty (FOU) coefficient of the SIT2-FLC is specifically adjusted to enhance the LFC performance. Additionally, a deep deterministic policy gradient (DDPG) with the actor-critic framework is considered to generate the supplementary control action, which is useful for the frequency stabilization by adapting to the randomness of load disturbances and RESs. Lastly, a model-in-the-loop (MiL) simulation is conducted to appraise the feasibility and applicability of the suggested design method from a systemic perspective.

The internal flow pattern analysis of a tidal power turbine operating on bidirectional generation-pumping

Using tidal energy can reduce environment pollution, save conventional energy and improve energy structure, hence it presents great advantage and is developing potential. Influenced by flood tide and low tide, a fully functional tidal power station needs to experience six operating modes, including bidirectional generation, pumping and sluice; the internal unsteady flow pattern and dynamic characters are very complicated. Based on a bidirectional tidal generator unit, three-dimensional unsteady flows in the flow path were calculated for four typical operating conditions with the pressure pulsation characteristics analyzed. According to the numerical results, the internal flow characteristics in the flow path were discussed. The influence of gravity to the hydraulic performance and flow characteristics were analysed. The results provide a theoretical analysis method of the hydraulic optimization design of the same type unit as well as a direction for stable operation and optimal scheduling of existing tidal power unit.

Suction caissons for cross-flow tidal power system

This paper describes a geotechnical site investigation and feasibility study of suction caisson foundations for fixed seabed tidal substructures in soft clay as part of the first US commercial-scale, grid-connected, tidal power installation located in Cobscook Bay, Maine. Feasibility was analysed through two-dimensional plane strain numerical modelling of the maximum capacity of a pair of rigidly connected suction caissons experiencing combined horizontal, vertical and moment loading when aligned with the direction of the current. Maximum load capacity for a single caisson diameter with varying skirt depths was investigated to determine effects of aspect ratio, uplift resistance of the windward leg and influence of shallow bedrock. Analyses in this paper indicate that suction caissons with relatively shallow skirts are a viable option to resist vertical and horizontal loading of the tidal power unit at the Cobscook Bay sites.