Adaptive Control of a Hybrid Energy Storage System for Wave Energy Conversion Application

Abstract

AGARWAL, APOORV. Adaptive Control of a Hybrid Energy Storage System for Wave Energy Conversion Application. (Under the direction of Dr. Subhashish Bhattacharya). A hybrid energy storage system (HESS), that comprises of a battery and a supercapacitor, is utilized to absorb the power and energy oscillations for a wave energy conversion system so as to inject a smooth power to the grid. Continuous variation in the wave profile presents a formidable challenge in terms of the power and energy allocation among the battery and supercapacitor. In this paper, an adaptive control strategy is proposed, wherein the power and energy sharing between the battery and super-capacitor is dynamically decided based on an optimization algorithm. The proposed algorithm is aimed at optimizing the total losses in the hybrid energy storage system while simultaneously maximizing the battery lifetime. Circuit simulation and experimental results from a hardware prototype are provided to validate the effectiveness of the proposed control scheme. Moreover, the change in wave profile and improvement of control strategy poses an additional challenge for sizing of HESS due to consistent change in the power sharing between battery and supercapacitor throughout its operation. Thus, a cost-optimal sizing of HESS is presented that takes into account the capital as well as the replacement cost.

Grid integration aspects of wave energy—Overview and perspectives

“…• Grid integration of WEC with no storage component • Grid integration of WEC with one storage component • Grid integration of WEC with HESS A review of these categories for grid integration studies is given in Table 6, from which it is evident that most grid integration studies use a DC link capacitor as short term storage, between back-to-back power converters. However, some use other storage systems such as super-capacitors [75], undersea storage (USS) [76] or HESS [62]. Most of the studies consider regular waves which do not represent real sea conditions.…”

“…Since there is no consensus on the type of wave energy device or PTO mechanisms, the WEC/PTO combinations presented in the literature are diverse, and involve both direct and indirect connections. Regarding grid integration, direct connection presents many challenges, considering the variability of the resource, usually requiring the addition of a storage component [62]. However, for grid integration of any device, the problem of output power fluctuations is common, and a power electronic conversion system is needed.…”

“…Most of the WEC control studies focus on Gen‐SC control to extract maximum power from the waves [8, 16, 62, 80–88, 91, 92, 103–109] and substantially less consideration is given to Grid‐SC control and power quality issues. It is also noted that most of the grid integration studies use simplified hydrodynamic models of WECs, which are not representative of real WECs.…”

Evaluation of Different Methodologies for Wave Energy Conversion Systems Integration into the Power Grid Using Power Hardware-in-Loop Emulation

“…In addition, energy storage devices are proving to be a viable solution for ensuring a smooth power output, as well as their ability to store excess energy in scenarios where production exceeds demand. The incorporation of efficient energy storage solutions becomes crucial for maintaining a stable and reliable power supply [16,17]. Therefore, the integration process requires not only cutting-edge technologies in power electronics but also sophisticated control in order to optimize the performance of WEC systems within the broader landscape of distributed energy sources.…”

Dimensioning Methodology of an Energy Storage System Based on Supercapacitors for Grid Code Compliance of a Wave Power Plant

“…Performance of the control system is evaluated in two case studies, fixed and variable operating speed. In [31] an optimization algorithm is aimed at splitting the power required between the battery and SCs of a HESS. This ESS is used to smooth the power oscillations for a wave energy conversion connected to the public grid.…”