Stefan Daraban

A novel global MPPT based on genetic algorithms for photovoltaic systems under the influence of partial shading

This paper presents a novel maximum power point tracking (MPPT) algorithm, based on genetic algorithms (GA). This algorithm is used for searching the global maximum power point (GMPP) for photovoltaic systems affected by partial shading. The “Perturb and Observe” (P&O) algorithm is embedded into the GA function for improving the optimisation process. By adding this functionality to the algorithm, the number of iterations and the population size is low, thus finding the MPP in a short time. Description of this algorithm and its performances will be detailed in this article, verified through simulation and experimental results.

A Maximum Power Point tracker for a photovoltaic system under changing luminosity conditions

In order to increase the output efficiency of a PV energy system, it has to be forced to operate near the maximum power point (MPP). A photovoltaic (PV) system, including Maximum Power Point Tracking (MPPT) controller that extracts the maximum possible output power from the solar panel is built. Simulation and experimental results show that the proposed system, making use of several MPPT control algorithms (Perturb and Observe (P&O), Incremental conductance (INC), Fuzzy Logic), provides good tracking performance.

A comparison between digital and analog control for a buck converter

This paper presents an approach of digital control with average current mode control. The model takes into account the non idealities of the components, the discrete time modeling of the Z transform, sampling, delays in the control loop and the quantization of coefficients for the control loop. First the analog compensation is made and then based on the poles and zeros, the bilinear function in Matlab is used to find the coefficients. The model is simulated in PSIM with step load current.

Single-stage low cost grid connected inverter in photovoltaic energy applications

Due to the rising fuel costs and growing worldwide demand for electricity, renewable energy sources become a necessity rather than a luxury. This paper presents an original control strategy for a buck-boost based converter used as a low cost inverter in a photovoltaic (PV) system. The main objective of the inverter is to harvest maximum power from the PV module and to inject it into the grid. The design of the converter is detailed and, together with the control method, a macro-model for the inverter is proposed. The macro-model is developed in order to have shorter simulation times and test various maximum power point tracking (MPPT) algorithms. Simulations and experimental results validate the proposed PV system.

A novel implementation of a Maximum Power Point Tracking system with digital control

This paper presents a novel Maximum Power Point Tracking(MPPT) method with digital control, together with an original Perturb and Observe (P&O) algorithm with variable step size. The step size calculation is independent of the slope of the power-voltage (P-V) characteristic of the solar panel. Simulation and experimental results are provided to show the efficiency of the system.

A novel global MPPT algorithm for distributed MPPT systems

This paper is focused on the implementation of an original algorithm for global maximum power point tracking (GMPPT) in photovoltaic systems. The algorithm detects when partial shading occurs, thus eliminating unwanted voltage sweeping. The paper gives a detailed analysis on how the algorithm succeeds in finding the global maximum power point (GMPP) in a short time and all its highlights. The system is controlled by a DSP which implements a voltage and a current loop for a better response of the system in case of a luminosity step change. Simulation and experimental results are finally provided to verify the performance of the system.

Microgrid model for fast development of energy management algorithms

The demand for electricity production increased in the last ten years leading to large investments and losses in the electricity grids. This forms the basis of decentralized hybrid energy system where the energy is produced in close proximity to the end user. This paper presents a simulation model for intelligent microgrids with distributed generation, also known as Smart Microgrids, focusing on the reduction of the simulation time in order to allow fast development of energy management algorithms. Photovoltaic panels and wind generators will be used as renewable energy primary sources and batteries as storage.

Novel Control for a Buck Converter used in a DMPPT System

Abstract This paper is focused on the digital implementation of a voltage and a current loop for a buck converter used in distributed maximum power point systems (DMPPT). It presents the importance of an additional control to help the maximum power point tracking (MPPT) algorithm. The paper gives a detailed small signal analysis and describes the method for compensating the current and voltage loop, making the stability of the system independent of the operating point on the power voltage (P-V) characteristic. The paper also proposes an original Perturb and Observe (P&O) algorithm with variable step size to search a local maximum. The calculation of the step size is independent from the slope of the solar panels P-V characteristic, making the tracking performances independent of the PV module. Simulation and experimental results are finally provided to verify the performance of the system.

Digital control of bidirectional DC-DC converters in Smart Grids

The interest in the development towards intelligent microgrids which use renewable energy as primary sources has significantly increased in the last two years. The present paper examines and proposes a new digital control solution for bidirectional DC-DC converters. In order to control the converter in both directions the novel algorithm uses the current that charges and discharges the storage devices. The study treats and solves problems related to the battery charging algorithms and the power flow direction change.

A comparison between Sepic and Buck-Boost converters used in maximum power point trackers

This paper presents a comparison between an analog compensated Sepic converter and a step down - step up converter (Buck-Boost) in a novel maximum power point tracking (MPPT) system. Both converters have advantages and disadvantages that will be pointed in this article. The algorithm that is used to provide the MPP for solar panels is Perturb and Observe (P&O) with three point weightings. Both simulations and practical results are analyzed and compared, afterwards conclusions are drawn.