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In almost all European countries, the penetration of wind power systems and the wind turbines size continuously increases. Therefore, the grid code requirements are more and more restrictive concerning the necessity that the wind turbine to remain connected to the grid during a fault situation. This paper analyzes the possibilities to have more accurate wind generation transient stability models for...
Nowadays, fossil fuels are depleted more and more. Renewable energy is one of the best solutions to replace conventional energy. The significant growth of Renewable energy sources indicates that it plays an important role in national energy system in near future. Distributed Generation (DG) technology is one of the technologies that gains more and more attention all around the world. According to...
Industry development and quality assurance in this field always addresses energy requirements that are likely to grow in the future. Among renewable energy sources, it is impossible not to mention the powerful increasing development of wind and sun energy systems. These sources of energy bring a large amount of electricity to almost all European countries. It is therefore possible to say that these...
Under partial shading conditions caused by the unevenly radiation and other ambient environmental conditions the operation of solar cells is influenced. Depending on the degree of shading, the phenomenon causes the decrease of solar cells output power. In the present paper two bypass diode configurations are compared, PV module with a bypass diode across each cell and with a bypass diode across each...
The paper presents the technical and economic analysis of a hybrid system based on renewable sources for a Campus for students cluster building in Romania, Bucharest. The renewable system consists in micro-wind turbine, solar modules and biomass power plant with battery storage. The cluster of buildings will allow rebalancing the demand between buildings, achieving in this way peak shaving of power...
The temperature, radiation and other ambient environmental conditions are influencing the operation of solar cells. The shadowing phenomenon on solar cells causes the decrease of their output power. This paper analyses the effects of bypass diode configurations on photovoltaic systems operation under completely shadowed conditions. The authors analyze and propose several bypass diode configurations...
Doubly-Fed Induction Generator (DFIG) Wind Turbine (WT) is rather sensitive to power system faults and requires specific power converter protection, namely a crowbar. When the crowbar is triggered, the rotor is short circuited over the crowbar impedance, the rotor-side converter (RSC) is incapacitated and therefore the DFIG operates as a squirrel-cage induction generator (SCIG) that tends to drain...
Due to the non-linear nature of diode based PV model, the accurate design of PV module is a difficult task. This paper proposes a comprehensive simulator developed in Matlab and Simulink for a photovoltaic (PV) module using a double diode model. To search extra internal parameters that are not provided by the manufacturers, we have provided numerical methods, suitably implemented to face the nonlinear...
Doubly-Fed Induction Generator (DFIG) Wind Turbine (WT) can be affected by power system faults and requires crowbar protection. When the crowbar is triggered, the rotor is short circuited over the crowbar impedance, the DFIG operates as a Squirrel-cage Induction Generator (SCIG) that tends to drain large amount of reactive power from the grid during fault, potentially causing a voltage drop. In this...
This paper proposes a control system, for crowbar protection and voltage support, for wind turbines equipped with doubly fed induction generator. The control system based on PI controller enables the low voltage ride through capability of the wind turbines. The reactive power control of doubly fed induction generators is mostly achieved by controlling its rotor side converter. The proposed control...
In wind power plants typically squirrel-cage induction generators (SCIG) tend to drain large amount of reactive power from the grid, potentially causing a drop voltage. To improve SCIG’s power quality and transient stability, this paper investigates a new pitch angle control strategy, including normal scheme and Fault-Ride-Through (FRT) scheme, based on hybrid of PI and Fuzzy logic technique. In particular,...
The paper analyzes the capability of a wind power plant, based on doubly-fed induction generators (DFIGs) with an improved control system, to fulfill low voltage ride-through (LVRT) capability of the wind turbines providing the reactive power support. According to grid code requirements, tripping of wind generators under grid faults is not allowed. The sensitivity of DFIGs to grid faults requires...
In the past, wind power penetration was extremely limited compared to the total power production. As a result, the interconnection requirements for wind farms were not included in the grid codes. However, in the recent years, the significant amount of energy injected by wind farms has already impacted the power system, both from a technical and a regulatory point of view in the recent years. Large...
Wind system using a fixed-speed wind power generation SCIG (Squirrel-cage Induction Generator) tends to drain large amount of reactive power from the grid, potentially causing a drop voltage and perhaps voltage stability conundrum. To improve the SCIG's low voltage ride through (LVRT) characteristics, this paper presents a new control strategy for a variable-speed wind power generation DFIG (Doubly-fed...
Touch sensors are one of the most fundamental input devices of many different applications these days. However, most dominant 2D touch sensing technologies are based on a grid of connections and sensors, which are thick and cumbersome. Thus flexibility and form factor do matter. In this paper, we propose an algorithm to design a flexible two-dimensional touch-sensitive surface using inkjet printing...
In order to optimize energy consumption in smart grid, demand side management has gained a lot of attention recently. While existing research works attempt to optimize energy consumption either from the view point of the power company or that of users, we investigate whether it is possible to consider both parties' interests at the same time. In this paper, we propose a novel energy price model, which...
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