Power Point Tracking Control Strategy Research Articles

Modeling and Simulation of Three Phase Photovoltaic Grid-Connected Generation System

According to the principle of photovoltaic(PV) grid-connected generation, the maximum power point tracking (MPPT) and grid-connected control strategy were presented in this paper. Based on the V-I characteristic curve of photovoltaic array, it built the mathematic model of photovoltaic array and the MPPT algorithm. Through adopting the double-loop feedback control strategy, it achieved the unit power factor control. Lastly, with the example system, it implemented the simulations analysis including the sunlight changing and the temperature changing. The simulation results show that the proposed models and the control strategy are correct.

Computer-Based Simulation and Scaled Laboratory Bench System for the Teaching and Training of Engineers on the Control of Doubly Fed Induction Wind Generators

Among the existing renewable sources, wind energy is reaching production rates that are becoming important on the worldwide energy scene. Since the control of these wind generators is a very technical discipline, practical teaching methodologies are of special relevance. Paradoxically, in the past, the training of engineers specializing in this area has lacked the practical component represented by field tests, due to the difficulty of access to this kind of installation. This paper presents a system designed for use both in teaching and training procedures for control strategies for wind generators with doubly fed induction generator (DFIG) technology. The system includes two phases or levels of use: the first being a simulation phase based on computer models, and the second, an advanced level which allows for the conducting of tests on a laboratory scaled workbench composed of a wind turbine emulator coupled to an electric generator. With this equipment, the effectiveness of the wind generator regulation systems can be analyzed from the point of view of the maximum power point tracking control strategy, as well as from that of the contribution produced by the wind generator to the control of the operation of the electric grid to which it is connected.

Sequential ESC-Based Global MPPT Control for Photovoltaic Array With Variable Shading

The photovoltaic (PV) systems are often subject to shading in practical operation, which often results in multipeak power-voltage (P-V) characteristics. Most existing maximum power point tracking (MPPT) control strategies are local-optimum oriented, based on the gradient search or its variations, e.g., perturb-and-observation (P&O) or extremum seeking control (ESC). In order to deal with the multimodal P-V characteristics for PV array with variable shading, this study proposes a sequential ESC-based global MPPT control strategy, based on approximate modeling and analysis for the P-V characteristics under variable-shading circumstances. For the multipeak P-V characteristic curve, the bound of variation for the turning-point voltage is found, and based on which the initial voltage for the segmental search can be set. The local minimum of power for the previous segment is used as the start of the next segment, and thus the initial voltage can be set with consistent bound. Such a sequential scheme can thus significantly reduce the searching interval, i.e., the searching efficiency. Another parallel analysis was conducted for the staircase current-voltage (I-V) characteristic for variable-shading situation. It reveals that the current step size is proportional to the change of shading levels. The current profiles obtained by the sequential ESC-based global MPPT search can thus be used to indicate the shading distribution. Simulation study of partially shaded PV panels validates the modeling analysis and the proposed global MPPT.

A Cost-Effective High-Efficiency Power Conditioner With Simple MPPT Control Algorithm for Wind-Power Grid Integration

In this paper, a novel grid integration system for a variable-speed wind turbine using an interior permanent-magnet synchronous generator (IPMSG) is developed. The power conditioner system (PCS) consists of a series-type 12-pulse uncontrolled diode rectifier powered by a phase-shifting transformer and then cascaded to a pulsewidth-modulated (PWM) voltage source inverter. The active current of the grid-side PWM inverter is only controlled to follow the optimal active current reference which is determined by using a simple maximum power point tracking (MPPT) control strategy. The MPPT algorithm requires only three sensors in order to track the maximum power of the wind turbine. The most significant advantage of the proposed system is that the passive filter together with a series-type 12-pulse rectifier provides high efficiency by compensating the power factor angle of the IPMSG and suppresses distortions presented in the IPMSG voltages and currents. The laboratory results indicate that the proposed construction and scheme are simple, cheap, and efficient.

Harmonic Mitigation, Maximum Power Point Tracking, and Dynamic Performance of Variable-speed Grid-connected Wind Turbine

This article presents a method for harmonic mitigation and maximum power point tracking for a variable-speed grid-connected 20-kW wind turbine. The wind energy conversion system consists of a permanent magnet synchronous generator driven by variable-speed 20-kW wind turbine. The output of the permanent magnet synchronous generator is connected to a single-switch three-phase boost rectifier to generate DC voltage, which feeds a current-controlled inverter to interface the system with the electric utility. The single-switch three-phase boost rectifier is an active power factor correction technique to maintain the power factor at the permanent magnet synchronous generator side to nearly unity and mitigate the permanent magnet synchronous generator current harmonics. To mitigate inverter output current and voltage harmonics, an LCL filter has been used. A complete analysis of the harmonic content has been done everywhere in the system. The results show that the proposed maximum power point tracking control strategy succeeded to track the maximum wind power irrespective of the wind speed. This strategy in presence of an LCL filter achieved harmonic mitigation at the permanent magnet synchronous generator and inverter output sides. The dynamic response of the wind energy conversion system is tested under a three-phase fault condition. For comparison purposes, an active power filter is designed and checked against the single-switch three-phase boost rectifier for harmonic mitigation at the permanent magnet synchronous generator side.

Experimental Comparison of Performances of Grid Connected Small Wind Energy Conversion Systems

This paper presents an experimental comparative study of performances in terms of efficiency on two possible grid connected small wind turbine systems. One of the systems is based on Permanent Magnet Generator (PMG) and the other system is based on Wound Rotor Induction Generator (WRIG). The Power Conditioning System (PCS) for grid connection of the PMG-based system requires a rectifier, boost converter and a grid-tie inverter, while the WRIG-based system employs a rectifier, a switch and an external resistance in the rotor side with the stator directly connected to the grid. Experimental test benches for both systems are implemented using Wind Turbine Emulator (WTE) and Maximum Power Point Tracking (MPPT) control strategy. The procedure for calculate the PCS losses, energy capture and energy loss is presented. The expected efficiency of the systems is investigated for wind distributions at eight sites in Newfoundland and Labrador. It is shown that a WRIG-based system could provide 5% higher efficiency in contrast to a PMG-based system and could be an optimum alternative in the small wind energy domain.

Intelligent approach to maximum power point tracking control strategy for variable-speed wind turbine generation system

Abstract To achieve maximum power point tracking (MPPT) for wind power generation systems, the rotational speed of wind turbines should be adjusted in real time according to wind speed. In this paper, a Wilcoxon radial basis function network (WRBFN) with hill-climb searching (HCS) MPPT strategy is proposed for a permanent magnet synchronous generator (PMSG) with a variable-speed wind turbine. A high-performance online training WRBFN using a back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller is designed for a PMSG. The MPSO is adopted in this study to adapt to the learning rates in the back-propagation process of the WRBFN to improve the learning capability. The MPPT strategy locates the system operation points along the maximum power curves based on the dc-link voltage of the inverter, thus avoiding the generator speed detection.

Modelling and control of a marine current turbine-driven doubly fed induction generator

This paper deals with the modelling and control of a variable speed doubly fed induction generator-based marine current turbine with and without tidal current speed sensor. The proposed maximum power point tracking control strategy relies on the resource and the marine turbine models that were validated by experimental data. The sensitivity of the proposed control strategy is analysed regarding the swell effect because it is considered as the most disturbing one for the resource model. Tidal current data from the Raz de Sein (Brittany, France) are used to run simulations of a 7.5-kW prototype over various flow regimes. Simulation results are presented and fully analysed.

A Maximum Power Point Tracking Control Scheme for PV System Based on Limit Cycle Operation

This paper proposes a new simple maximum power point tracking (MPPT) control scheme for a PV system without using conventional “mountain climbing” optimum operating point searching technique. Although no information of voltage and current is needed on PV array side, the generated output power on ac system side can be automatically maximized by utilizing limit cycle phenomena occurring on equilibrium/non-equilibrium boundary of system power flow. After explaining the operating principle of proposed scheme, it is applied to a common “boost chopper/3-phase inverter” interface power converter system. The experimental results show an availability of the new control scheme.

A Maximum Power Point Tracking Control Scheme for PV System Based on Power Equilibrium and Its System Design

Since maximum power point tracking (MPPT) control is useful to realize an efficient PV system, many papers on MPPT scheme have been proposed. In most cases, they basically depend on so-called mountain climbing method which depends on the information of output power of PV array. Authors previously proposed a new MPPT control scheme for PV system connected in parallel with the ac system line. The system also depends on mountain climbing method. However, it needs no sensors or calculation for PV array power detection, and utilizes an interior control signal of dc link voltage control loop itself. For this reason, system response and stability greatly depend on the main circuit and control system parameters. This paper shows system design to ensure well-damped stable operation and fast response based on system analysis. Response of the experimental system has been proved fast enough for practical use.