Design and experimental implementation of a hysteresis algorithm to optimize the maximum power point extracted from a photovoltaic system

In the several last years, numerous Maximum Power Point Tracking (MPPT) methods for photovoltaic (PV) systems have been proposed. An MPPT strategy is necessary to ensure the maximum power efficiency provided to the load from a PV module that is subject to external environmental perturbations such as radiance, temperature and partial shading. In this paper, a new MPPT technique is presented. Our approach has the novelty that it is a MPPT algorithm with a dynamic hysteresis model incorporated. One of the most cited Maximum Power Point Tracking methods is the Perturb and Observer algorithm since it is easily implemented. A comparison between the approach presented in this paper and the known Perturb and Observer method is evaluated. Moreover, a new PV-system platform was properly designed by employing low cost electronics, which may serve as an academical platform for further research and developments. This platform is used to show that the proposed algorithm is more efficient than the standard Perturb and Observer method.Peer ReviewedPostprint (published version

Design and Control of Islanded Microgrid

The control of frequency and power has always been a problem in the development of microgrid. This thesis focuses on the design and control of islanded microgrid; more specifically, it includes the design of the PV system and wind power system and the control of the frequency, voltage and the power output of the islanded microgrid. Microgrid consists of the power sources, the control system, the distribution network and the load. More specifically, the power sources are composed of PV system and wind turbine system; the control system in the microgrid includes the droop controller, the Maximum Power Point Tracking (MPPT) controller and the pitch controller. This thesis is dedicated to researching the control of the islanded microgrid. The frequency and the power output in islanded microgrid can be controlled by using different kinds of controllers. Since PV and wind turbine have different structures and characteristics, the control systems for the PV and wind turbine are different. It is also necessary to let the PV system and the wind power system communicate with each other in order to control the total power output to the load. The design of the islanded microgrid includes the design of the PV system and design of the wind power system. This thesis includes five chapters. The first chapter includes the introduction to the microgrid, some background and motivation, literature review and the expected contributions. Then the thesis describes the PV system and the wind power system in chapter 2 and chapter 3 respectively. In both chapter 2 and chapter 3, the general structure of each system is shown first and then the details of the systems are discussed. The control system includes the controllers such as the MPPT controller, the pitch controller and the droop controller. A modified controller is introduced in chapter 2, which is the droop controller integrated with virtual inertia. A testing case comparing the frequency control with the modified droop controller and the droop controller is also shown in the same chapter. The fourth chapter tests the control system of the microgrid by showing five testing cases and comparing two different experimental sets (load 1 and load 2); the last chapter concludes the thesis and discusses the future work of the design

Extremum seeking control with data-based disturbance feedforward

This paper presents a practical extension to the classical gradient-based extremum seeking control for the case when the disturbances responsible for the changes in the extremum of a related performance function can be measured. The additional information is used to improve accuracy, convergence speed and robustness of the underlying ESC scheme. Based on the disturbance measurements a map between them and the optimal inputs is iteratively constructed and used as an extremum seeking feedforward. A supervising state-machine is designed to regulate feedforward and search processes ensuring the latter is conducted in the close vicinity of an extremum. The search is based on the sinusoidal input perturbation introduced each time the disturbance is detected and removed once the optimal set-point is identified. Simulation results for the cases of photovoltaic and turbine driven electrical generator systems demonstrate the benefits of the presented design

Extremum seeking control with data-based disturbance feedforward

\u3cp\u3eThis paper presents a practical extension to the classical gradient-based extremum seeking control for the case when the disturbances responsible for the changes in the extremum of a related performance function can be measured. The additional information is used to improve accuracy, convergence speed and robustness of the underlying ESC scheme. Based on the disturbance measurements a map between them and the optimal inputs is iteratively constructed and used as an extremum seeking feedforward. A supervising state-machine is designed to regulate feedforward and search processes ensuring the latter is conducted in the close vicinity of an extremum. The search is based on the sinusoidal input perturbation introduced each time the disturbance is detected and removed once the optimal set-point is identified. Simulation results for the cases of photovoltaic and turbine driven electrical generator systems demonstrate the benefits of the presented design.\u3c/p\u3