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Photovoltaic energy is one of the key renewable energy resources of present day. Optimal usage of maximum power available from photovoltaic panels still remains an engineering challenge. Focusing on this issue, a novel photovoltaic power generation system based on a low voltage DC generation with panel level MPPT based on look up table, medium frequency square wave AC link, medium frequency transformer,...
This paper delineates a mechanism to attain decentralized control of a high-frequency distributed power system (HFDPS) based on local observation and/or estimation at the source and load ends. An acceptable dynamic performance of the independent control eliminates/reduces the need for high-speed communication (that typically needs to be high because of HF power transfer) between the source- and load-end...
A Virtual Power Plant (VPP) composed of distributed energy resources (DER) with load and generation forecasting is presented in this paper. The large-scale integration of renewable energy and energy storage systems have introduced many technical and economic challenges to both customers and utilities. High levels of renewable power injection might reduce grid stability due to intermittencies. The...
The insertion of grid connected photovoltaic (PV) in the power systems have occurred mainly at low and medium voltage. Besides, due to solar irradiance variation, these converters have excess capacity that can be used to provide ancillary services to the main grid. Therefore, this work is focused on the analysis of how PV inverters can perform ancillary services, supporting the grid. Control strategies...
The use of fossil fuels and the greenhouse gases emission is a growing concern of the international community. For this reason, the research and development of alternative sources are forcing down the costs associated with renewable energy sources. Photovoltaic energy production is the best example of these exponential growing rates at the last years. However, the output power provided through the...
This paper deals with the simulation of a Dynamic Voltage Restorer (DVR) for compensating electric power grid disturbances, in order to protect sensitive loads. The DVR is composed for power electronics converters (AC-DC and DC-AC converters), a serie transformer and a control system. This control system is capable of detecting the disturbances and compensating them. The complete system (grid model,...
The main objective of a photovoltaic (PV) inverter is to inject the PV power into the ac-grid. Generally, due to variations in solar irradiance, inverters operate bellow their rated current. Therefore, this current margin can be used to ancillary services, such as harmonic current compensation. However, it is necessary to study the photovoltaic inverters voltage and current capability effects during...
This paper analyses the solar radiation profile of three cities of the Brazilian State of Santa Catarina and shows the calculation of the weighted average efficiency, aiming to allow efficiency maximization designs for the electrical energy processing in photovoltaic systems. By means of data obtained in climatic stations the electrical generation capacity of these stations is shown to optimize the...
A lifetime analysis was performed on the DC-link capacitor of a photovoltaic power-processing system composed of a boost converter in the first stage. It was investigated how the switching frequency and ripple current design choice affect the capacitor lifetime. Through an electro-thermal modeling, the capacitor operating condition was obtained for various levels of power processing, based on a real...
High-efficiency control of grid-tied inverters under unbalanced grid voltage condition is very important to improve the operation performance of the grid-tied inverters. On basis of instantaneous power theory of Current Source Inverter (CSI) under unbalanced grid voltage condition, this paper proposes a novel Quasi Direct Power Control (QDPC) strategy which adopts proportional resonant (PR) controller...
This paper presents a step-down converter with Resonant Switched Capacitor (RSC) that supplies high power light emitting diodes (LEDs), designed for DC nanogrids applications. The proposed converter differs from traditional RSC converters by ZVS (Zero Voltage Switching) turn-off and the stabilization of power delivered to the LEDs. A laboratory prototype of 10 W presented a maximum efficiency of 92...
The absence of modulator in model based predictive control technique for different converter topologies generates a variable switching frequency that produces high frequency harmonics and higher stress on the power semiconductor devices. In this paper, a novel model based predictive control strategy with a fixed switching frequency applied to a three-phase cascade H-bridge multilevel STATCOM is introduced...
This work aims to compare performance between Neutral-Point-Clamped (NPC) three-phase converters of two branches (NPC-2B) and three branches (NPC-3B). These converters are used as grid-side converters (GSC) in the back-to-back configuration of the type-3 turbine with doubly fed induction generator (DFIG). Like GSC, these converters perform two ancillary services: reactive support and harmonic compensation...
The use of wind turbine as electricity source is growing globally and as consequence the grid codes are becoming more restrict. The restrictions depends on the country that the system is installed and basically limits the system disconnections during determined faults and demands the injection or absorption of active or reactive power during those faults to ensure a fast return of the system to its...
The impact of converter-based loads on the power system is evaluated based on stability studies. This requires adequate load models. This paper deals with a time-domain model of an electric vehicle battery charger with grid support functionality (so-called controllable load). The dynamic properties of the components of a unidirectional 1,2 kW battery charger with input diode rectifier are discussed...
This paper deals with the robustness analysis of an anti-windup predictive current controller applied to a DFIG-based wind turbine in the presence of parameter variation. Experimental results were carried out, under the changing of the rotor speed, power and voltage sags, for a 3.7kW DFIG to verify the robustness of the designed controller.
Photovoltaic (PV) power plants are a form of renewable energy and their importance is increasing all around the world. In Brazil, the PV power plants connected to the grid are regulated through a credit compensation, in which the prosumer pays the difference between consumed and generated energy. Medium voltage consumers pay different prices for the energy consumed in peak load time and off-peak load...
In this paper, an efficient method of uncertainty analysis, the so-called Unscented Transform, is applied to a wind farm numerical model. Particularly, the effect of an uncertain wind speed on the DC bus voltage of the power converter, as a fault occurs, is considered. We show that the DC bus voltage is strongly influenced by the wind speed. Moreover, the proposed uncertainty analysis method computes...
This article presents some similarities of switched and linear converters and focuses on a Switched-Linear (SL) approach. The analysis shows that the goals of linear converters is similar to that of switched converters. The objective of the development of them is increasing the converter's manipulated power and efficiency. By mixing both structures is possible to produce a converter that has synthetic...
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