An Optimal Control Strategy for DC Bus Voltage Regulation in Photovoltaic System with Battery Energy Storage

Abstract

This paper presents an evaluation of an optimal DC bus voltage regulation strategy for grid-connected photovoltaic (PV) system with battery energy storage (BES). The BES is connected to the PV system DC bus using a DC/DC buck-boost converter. The converter facilitates the BES power charge/discharge to compensate for the DC bus voltage deviation during severe disturbance conditions. In this way, the regulation of DC bus voltage of the PV/BES system can be enhanced as compared to the conventional regulation that is solely based on the voltage-sourced converter (VSC). For the grid side VSC (G-VSC), two control methods, namely, the voltage-mode and current-mode controls, are applied. For control parameter optimization, the simplex optimization technique is applied for the G-VSC voltage- and current-mode controls, including the BES DC/DC buck-boost converter controllers. A new set of optimized parameters are obtained for each of the power converters for comparison purposes. The PSCAD/EMTDC-based simulation case studies are presented to evaluate the performance of the proposed optimized control scheme in comparison to the conventional methods.

Direct versus indirect illumination of a prototype luminescent solar concentrator

“…At the other extreme, PV panels do not perform as well when hot (Davis et al, 2001;Raga and Fabregat-Santiago, 2013;Skoplaki and Palyvos, 2009), while the LSC was shown to run cooler than silicon-based cells, again easing application and minimizing performance impact at high irradiation (Rajkumar et al, 2015). These results suggest the power output of the LSC device is less prone to spiking than that from a traditional silicon based solar panel, which could be an advantage when moving to increasingly renewable energy streams as a method to reduce the strain on the grid (Ahmed et al, 2008;Daud et al, 2014;Mitchell et al, 2005).…”

Control of a Charger/Discharger DC/DC Converter with Improved Disturbance Rejection for Bus Regulation

“…The charger/discharger converter is controlled to regulate the DC bus voltage within safe limits and simultaneously impose a given energy flow between the battery and the DC bus. Due to safety implications for the source and load, there are many research papers focused on regulating the DC bus voltage using charger/discharger converters: some of them are based on linear control [16,[23][24][25][26], others are based on intelligent control [13,[27][28][29][30][31][32], and others are based on non-linear control strategies [15,[17][18][19][20][21][22]. In particular, sliding-mode controllers (SMCs) have been widely used for this application to ensure global stability, robustness to parameter tolerances, higher bandwidth compared with classical linear controllers [17,22,33], and reduced implementation cost and complexity compared with intelligent controllers [31,34].…”

“…The solution proposed in this paper is aimed at providing a tight regulation of the DC bus voltage in a stand-alone power system based on renewable energy sources to ensure a safe operation. This objective is fulfilled by designing a sliding-mode controller for the battery charger/discharger to regulate the bus voltage under any power flow condition; however, in contrast to the solutions previously discussed [15,16,22,26], this new solution proposes including the DC bus current in the sliding surface to improve the disturbance rejection. Moreover, the proposed solution does not use a cascade control structure; hence, a single controller defines the MOSFET state based on the measurements of the battery current and bus voltage and current.…”

An Improved Fuzzy Logic Controller Design for PV Inverters Utilizing Differential Search Optimization

“…The implementation starts by resetting the DSA parameters, namely, number of iterations ( ), population size ( ), problem dimension ( ), and control parameters ( 1 and 2 ). The initial populations for the MFs are then generated and encoded according to (9). The next step involves the evaluation of the objective function using (10).…”

“…Recently, researchers have focused on the utilization of optimization techniques in PI controller tuning to achieve improved performance. An optimal DC bus voltage regulation strategy with PI controllers for a grid-connected PV system was suggested in [9]. In this work, the PI control parameters were optimized using the simplex optimization technique.…”