Please enter the words you want to search for:

EPE 2007 - Subtopic 13-6 - DS: Distributed, renewable energy systems (Joint EPE and IEEE Wind Day)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2007 - Conference > EPE 2007 - Topic 13: 'Electrical energy generating systems, renewable energy systems' > EPE 2007 - Subtopic 13-6 - DS: Distributed, renewable energy systems (Joint EPE and IEEE Wind Day)
	[return to parent folder]
	A Control Algorithm for Power Converters in the Field of Photovoltaic Application   By RACITI Angelo; SAPUPPO Carmelo; DI GUARDO Mario; CHIMENTO Filippo; MUSUMECI Salvatore	[View]   [Download]
Abstract: An improved digital control for SEPIC converter has been designed and implemented in order to extract the maximum power from a photovoltaic system. A Maximum Power Point Tracking (MPPT) algorithm has been used to increase the energy extracted from the source in a microcontroller based environment. Analyses of the electric behavior of the photovoltaic modules have been performed looking to create a mathematical model that has been represented by a lumped parameters circuit. Such a model is suitable for simulation runs with commercial software packages. The model parameters have been identified by means of measurements performed onto two different photovoltaic module technologies (crystalline and amorphous silicon). A V2 control algorithm was also implemented to establish a performance comparison with more common MPP strategies. The V2 algorithm allows evaluating the input power of the converter without current sensing devices being sufficient the knowledge of some converter parameters. The experimental system has been tested with both a low-power amorphous panel and a crystalline one. The obtained results by means of the used algorithms demonstrate good performances with high efficiency values in several working conditions and a shorter searching time of the MPP in comparison to other ones. The experimental converter has been tested with an output power of 100 W (5A, 20V). The resonant operations allowed also achieving very low values of the converter power losses.
	A current-controlled fuel cell system with short-time storage for gird feeding application   By VEIT Bjorn; KÖNIG Stefan; MEHLICH Heiko; MEHLICH Jan; JÄHNERT Stefan	[View]   [Download]
Abstract: For generation of required voltages and controlled energy transfer from fuel cell stacks, appropriate converter topologies are necessary. The stability of the stack against degradation and thus the possible lifetime does not meet the requirements for most applications yet. Dynamic fluctuations of the FC output power can accelerate the degradation process. Only a limited fuel cell current is allowed to prevent faster degradation of the FC-stack. A favorable topology for the combination of a fuel cell with a short time energy storage will be discussed. A fast AC-load response is possible in order to balance fluctuated consumer profiles and to improve the quality of the power fed into the grid.
	A Novel Maximum Power Point Tracker Controlling Several Converters Connected to Photovoltaic Arrays with Particle Swarm Optimization Technique   By MIYATAKE Masafumi; TORIUMI Fuhito; ENDO Tsugio; FUJII Nobuhiko	[View]   [Download]
Abstract: This paper deals with maximum power point tracking control of photovoltaic generators. Photovoltaic generation systems need maximum power point tracker because the PV power output depends on the operating terminal voltage and current. Further, the PV array exhibits two or more MPP's under partial shading condition and hence finding the MPP using conventional techniques is a difficult task. To overcome the difficulty, finding the MPP, the authors have proposed a novel MPPT algorithm by introducing Particle Swarm Optimization technique. Further, the proposed algorithm uses only one pair of sensors to control multiple PV arrays. This results in lower cost, higher overall efficiency and also the algorithm is simple. Proposed MPPT algorithm is verified through experimental studies. Several partial shading conditions were tested and in all these cases the algorithm takes about one second to reach the global MPP. The reachability to MPP is good in both shading and unshading.
	A novel Parallel Active Filter for Current Pulsation Smoothing on Single Stage Grid-connected AC-PV Modules    By KYRITSIS Anastasios; TATAKIS Emmanuel; PAPANIKOLAOU Nikolaos	[View]   [Download]
Abstract: The newest technology on decentralised grid-connected PV systems is the "AC-PV Module", which is characterised by a number of clear advantages over conventional large PV systems. Single stage topologies seem to be a rather attractive solution, for these applications, since in generally they are characterised by high efficiency, low cost and simple structure with high reliability due to reduced components count. On the other hand in single-phase AC-PV Module inverters, the power that is transferred to the power network has a large amount of power pulsation at twice line frequency. So a large ripple of voltage and current appears at the PV module output. Taking into account that there is a close correspondence between the power that flows from a PV module and the point of operation, this fact leads to reduced PV power generation. In order to overcome this defect, this paper presents a novel Current Pulsation Smoothing Parallel Active Filter (CPS-PAF) which is independent from the inverter topology and his operation mode. Purpose of the proposed CPS-PAF is the elimination of the low frequency PV current ripple. So the PV module can be operated close enough to the maximum power point and consequently the PV generated electricity power is maximised. The CPS-PAF conception, control and effectiveness are validated by PSpice simulation and experimental results accomplished on a laboratory prototype.
	A NOVEL TOPOLOGY WITH HIGH EFFICIENCY FOR GRID CONNECTED PHOTOVOLTAIC PCS    By MIN Byung Duk; KIM Taejin; LEE Jongpil; KIM Jonghyun; YOO Dong Wook	[View]   [Download]
Abstract: In this paper, new topology is proposed that can dramatically reduce the converter power rating and increase the efficiency of total PV system from analysis of PV characteristic curve. Since the output voltage of PV module has very wide voltage range, in general, the DC/DC converter is used to get constant high DC voltage. According to analysis of PV characteristics, in proposed topology, only 20\% power of total PV system power is needed for DC/DC converter. DC/DC converter used in proposed topology has flat efficiency curve at all load range and very high efficiency characteristics. The total system efficiency is the product of that of converter and that of inverter. In propose topology, the converter efficiency curve is flat all load range, the total system efficiency at the low power range is dramatically improved. The proposed topology is implemented for 200kW PCS system. This system has only three DC/DC converters with 20kW power rating each other. It is only one-third of total system power. The experiment results show that the proposed topology has good performance.
	A Simple Method for Analytical Evaluation of LVRT in Wind Energy for Induction Generators with STATCOM or SVC    By MOLINAS Marta; UNDELAND Tore; SUUL Jon Are	[View]   [Download]
Abstract: Low Voltage Ride Through (LVRT) has emerged as a new requirement that system operators demand to wind turbines. E-ON Netz, the major German transmission operator has introduced a LVRT grid code that is receiving wide acceptance and being used as a template for similar requirements from nearly every country with wind generation. STATCOM and SVC are both good candidates for providing LVRT for wind turbines with induction generators. This paper provides a new analytical approach that allows using torque-slip curves to evaluate induction generator stability limits when having shunt reactive compensation such as STATCOM or SVC as the LVRT solution for the wind generation. This analytical approach is proposed as screening method to assess stability and/or to estimate the required rating of the reactive compensation that will ensure stability in a given system. Analytical and simulation results compared are in good agreement and both indicate the advantage in using a STATCOM since it gives an increased transient stability margin and consequently enhanced LVRT capability compared to SVC. The proposed method can easily and reliably be implemented by wind farm developers and the utilities after the validation by simulations presented in this paper.
	A Single Sensor Type MPPT Control Method for PV Generation Systems   By ITAKO Kazutaka	[View]   [Download]
Abstract: This paper introduces a new MPPT control method for solar photovoltaic (PV) power generation systems. The proposed method include its ability to perform MPPT using only a single solar cell voltage detection sensor and simultaneously predicting the voltage necessary for load voltage control, which is essential to real systems. As a result, this control method offers advantages of the simplified hardware configuration and the low cost.
	A STAND-ALONE PHOTOVOLTAIC SYSTEM BASED ON DC-DC CONVERTERS IN A MULTI-STRING CONFIGURATION   By PINHEIRO José Renes; RODRIGUES Guilherme Fraçáo; HEY Héio Leães; IMHOFF Johninson	[View]   [Download]
Abstract: This work introduces an autonomous photovoltaic system, alternative to traditional systems, composed of a configuration with distributed DC-DC energy processing and maximum power point tracking, and presents a comparison of the generated energy by the input stages of a centralized autonomous system and by the proposed system. Experimental results show that the proposed system can present an increase of 16\% on the generated energy at the DC bus, in situations in which one or more photovoltaic panels are shaded, damaged or aged.
	Advanced modular communication concepts for data logging and conditioning in photovoltaic inverter systems   By MIELKE Jochen; IDE Peter	[View]   [Download]
Abstract: This paper describes an investigation in order to find an optimal solution for the communication of a PV installation. Most important is the quality of the collected data to be able to do detailed analysis. High investment costs make it necessary to get the PV installation controlled. In addition to that, because of variable power categories, different requirements in the data acquisition are also necessary. These requirements are overlapping various areas beginning from a LED in the PV inverter up to a data collection in a storage system. In addition to that, the price for a solution must be in a reasonable relationship to the size of the PV installation.
	Application to the Portuguese Power System   By FAIAS Sérgio; SOUSA Jorge; CASTRO Rui	[View]   [Download]
Abstract: Increasing integration of renewable sources introduce some new issues on the operation of the power system, such as potential unbalancing between generation and demand, especially in off-peak periods with high levels of hydro generation. This scenario can get worse when associated with the installation of a nuclear powerplant, which operates on a must run basis. This paper analyses the contribution of energy storage systems use to avoid future power generation and demand unbalance in the Portuguese power system. Moreover it is also presented an overview of the available energy storage technologies and the role of power electronics on its appropriate operation.
	Association of wind turbine based dispersed generators and storage systems to participate in primary frequency control    By COURTECUISSE Vincent; EL MOKADEM Mostafa; FRANCOIS Bruno; DEUSE Jacques; ROBYNS Benoit; PETIT Marc	[View]   [Download]
Abstract: The goal of this work is to develop a supervision strategy for hybrid generation systems. This strategy must allow to improve the grid insertion of wind turbine generators (WTG) by associating them some storage systems and foreseeable decentralized generator (FDG). To maintain a reference power and to contribute to the primary frequency control with a hybrid generator based on variable speed WTG, storage systems and FDG, a fuzzy logic supervisor is proposed. A detailed method to build this supervisor is proposed. The performance of this supervisor is shown with the help of simulation.
	Balanced Grid Currents in Three-Level Voltage-Source Inverters Connected to the Utility under Distorted Condition using Symmetrical Components and Linear Quadra   By ALEPUZ Salvador; BUSQUETS Sergio; SILVA Cesar; PONTT Jorge; RODRIGUEZ Jose; BORDONAU Josep	[View]   [Download]
Abstract: This paper proposes a control approach to achieve balanced grid currents in Three-Level Voltage-Source Inverters connected to the utility under dip or unbalanced condition. Fast sequence separation method for symmetrical components is used concurrently with Linear Quadratic Regulator in the current controller, in order to take advantage of the multivariable structure of the system. The harmonic content of the grid voltages can affect the type of sequence separation method to be used. Controller parameters are tuned by simulation. Experimental results have been obtained with a distorted grid, with significant harmonic content, under dip or unbalance condition, verifying the validity of the proposed control approach.
	Centralized supervision of reactive power generation for a wind farm    By BERKOUK E.M.; FRANCOIS Bruno; GHENNAM T; BEUGNIEZ Aurelien; ROBYNS Benoit	[View]   [Download]
Abstract: Vector field control of Doubly Fed Induction Generators enables to generate/absorb reactive power. These machines are more and more used in wind farms. Their reactive power generation capabilities are related to their operating points. This paper presents a centralized supervision of the reactive power control for a wind farm. A weighting distribution strategy has been used in order to determine the reactive power reference for each wind generator.
	Control and Energy Management of a Wind-Photovoltaic Hybrid System   By ROBOAM Xavier ; DALI Mehdi; BELHADJ Jamel; BLAQUIERE Jean-Marc	[View]   [Download]
Abstract: In this paper, we have designed a micro-generation energy system obtained by interconnecting a wind turbine with a photovoltaic generator and characterized by Very Low Voltage (VLV) node coupled to a battery storage and DC loads. The control strategies of the sources are based on power, voltage and current control with Maximum Power Point Tracking (MPPT). Experiments based on a physical emulator of the hybrid system with a lead acid accumulator and its DC load is considered. The development of experiments is necessary to validate theoretical studies. The real time supervision and the energy management of the hybrid system is presented and detailed. Experimental results are presented and discussed showing the relevant behavior of the energy management strategy.
	Evaluation of Three-phase Transformerless PV Inverter Topologies   By SUMNER Mark; FLORICAU Dan; TEODORESCU Remus; KLUMPNER Christian; RODRIGUEZ Pedro; KEREKES Tamas	[View]   [Download]
Abstract: This paper analyzes and compares the most common single-stage transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. The change in the leakage current to ground will be investigated and a comparison of the selected topologies will be carried out, based on the component ratings, output voltage levels and filter size.
	Exercise Bike Powered Electric Generator for Fitness Club Appliances   By JARNUT Marcin; STRZELECKI Ryszard; BENYSEK Grzegorz	[View]   [Download]
Abstract: A generator powered by a stationary bicycle for the purposes of generating electricity for fitness club appliances is considered. A generator is connected to a stationary bicycle in such a way as the circular rotation of the front wheel rotates the coils of wires inside the generator between the poles of the magnets inside the generator. The resulting Direct Current is channeled to the attached battery bank and converted into different usable DC voltage levels as well as AC voltage, just to increase the number of electrical appliances possible to connect.
	Fast On-Line Symmetrical Components Separation Method for Synchronization and Control Purposes in Three Phase Distributed Power Generation Systems   By SILVA Cesar; RODRIGUEZ Jose; ALEPUZ Salvador; BORDONAU Josep; PONNT Jorge	[View]   [Download]
Abstract: This work introduces a fast symmetrical components separation method, in order to obtain instantly positive and negative phase sequence. Therefore, intrinsic delay presents in other sequence detection methods, like Delayed Signal Cancellation, is removed. Accurate positive and negative phase-sequence components are obtained with the proposed method, tested by simulation under different grid voltage dips or unbalance condition. Experimental results show good performance in presence of a clean grid voltage waveforms. However, when grid voltages are distorted due to the harmonic content, the outputs of proposed system deliver a significant and undesirable amount of ripple. Therefore, an additional block to eliminate grid voltage harmonics is needed in order to take advantage of the proposed method.
	Fault Ride-through Capability Implementation in Wind Turbine Converters Using a Decoupled Double Synchronous Reference Frame PLL   By IOV Florin; RODRIGUEZ P.; BLAABJERG Frede; LUNA A.; TEODORESCU Remus	[View]   [Download]
Abstract: This work exploits the Decoupled Double Synchronous Reference Frame PLL (DDSRF-PLL) as an effective method for grid synchronization of WT's power converters in the presence of transient faults in the grid. The DDSRF-PLL uses a dual synchronous reference frame and a decoupling network to effectively separate the positive- and negative-sequence voltage components in a fast and accurate way. Excellent behavior of the DDSRF-PLL is demonstrated experimentally. Once sequence components of the faulty grid voltage are properly identified several algorithms computing current references are developed. Additionally, different power delivery strategies to ride-through grid faults are discussed and simulations results are presented. As a conclusion, it will be demonstrated that certain control strategies ensure a stable operation of the front-end inverter while the grid voltage is supported by means of injection of instantaneous reactive power at the same time.
	High-Resolution Phase Shift and Digital Implementation of a Fuel Cell Powered UPS System   By TAO Haimin; DUARTE Jorge; HENDRIX Marcel	[View]   [Download]
Abstract: This paper presents the digital implementation of a single-phase fuel cell powered uninterruptible power supply (UPS) and distributed generation (DG) system. The power conditioning unit of the system consists of a voltage source inverter and a three-port bidirectional dc-dc converter interfacing the fuel cell and inverter with a supercapacitor. It is shown that the control of the whole system including both the dc-dc and dc-ac stages can be carried out by a single digital signal processor (DSP). In particular, in order to eliminate limit cycle oscillations in digitally controlled dc-dc converters, the generation of high-resolution phase shifts is explained in detail. The system is suitable for residential applications and can improve the power quality for the local user. Practical design issues such as the state-of-charge (SOC) management of the supercapacitor and prototype design details are discussed. Experimental results from a 3.5~kW prototype are presented to verify the effectiveness of the digitally implemented control scheme.
	Improved STATCOM Operation Under Transient Disturbances for Wind Power Applications   By ARENAL REDONDO Beatriz; ETXEBERRIA-OTADUI Ion; VISCARRET Unai; ZAMAKONA Izaskun; IBIRICU Javier	[View]   [Download]
Abstract: This paper presents an optimized STATCOM control for wind power applications. The transient behavior of fixed-speed wind farms can be improved by injecting large amounts of reactive power during the fault recovery. This application requires a high dynamic converter, which must also be capable of working under transient unbalanced conditions. Here, a stationary control structure is proposed, which is based on resonant regulators and a DFT synchronization algorithm, which allows an optimized reactive power injection during voltage dips occurred in the grid. The proposed structure is validated experimentally using a reduced scale STATCOM prototype, showing that it is well adapted for the concerned application.
	Inverter Power Sizing Considerations in Grid-Connected PV Systems   By VELASCO Guillermo; CONESA Alfonso; GUINJOAN Francesc; PIQUE Robert	[View]   [Download]
Abstract: This work is devoted to establish preliminary criteria helping in the choice of a central inverter power sizing in grid-connected PV systems in order to maximize the yearly energy injected to the grid. These criteria come from an estimation of the injected energy by means of a set of Matlab®-based simulations involving a simulation-oriented model of the PV conversion chain, the environmental data of several PV Spanish sites as well as the PV installation mounting type characteristics. The simulation results show that the current practice of under-sizing the inverter maximum power with respect to the PV generator nominal power may not be the best choice in terms of yearly produced energy and also evidence the strong impact of the PV generator operating temperature in the choice of the optimal inverter power sizing.
	Modelling & Control of a Bidirectional Converter for a Stand-alone Photovoltaic Power Plant   By ZHANG Li; CHONG Benjamin Vui Ping; DEHGHANI Abbas	[View]   [Download]
Abstract: The paper presents an investigation of a DC/DC bidirectional converter. A new state-space model has been developed to analyse the bidirectional current flow characteristics. This model has been incorporated into a simulation program for a stand-alone photovoltaic plant that includes a lead-acid battery for energy storage. An integrated control system is developed and evaluated in the simulated system. Results show that the model is accurate and offers a significant improvement in the computational efficiency.
	Modelling and control of a 100kW photovoltaic inverter with an LCL grid filter for distributed power systems   By GONZALEZ-ESPIN Fran; SANDIA Jesus; GARCERA Gabriel; CALVO Jesus; VALES Manuel; FIGUERES Emilio	[View]   [Download]
Abstract: The aim of this paper is to analyze the control loops stability of three-phase photovoltaic inverters for distributed power generation. The main issues regarding the design of the control stage are outlined, including a small signal model of the photovoltaic cells for control purposes and the influence of high order grid filters on the system stability. Experimental results carried out on a 100kW inverter are presented to validate the analytical results. The experimental inverter generates a balanced set of currents with a distortion lower than 3\%.
	Phase-Locked Loop with Adaptive Signal Cancellation for Three-phase Network Side Voltage Source Inverter   By SULKOWSKI Waldemar; NORUM Lars; ÖSTREM Trond	[View]   [Download]
Abstract: Circuits for synchronizing power converters to the three-phase utility voltages are often sensitive to voltage disturbances. Some kind of filtering device is needed. Voltage information is also important for system protection. Both voltage and frequency disturbances could be disadvantageous for the equipment. In this paper an alternative solution for improving the performance of a synchronizing circuit based on a phase-locked loop is proposed. It takes advantage of signal delay cancellation for calculating the symmetrical components of the three-phase voltages, but the delayed signal is estimated by an adaptive method. Other solutions for filtering input voltages are available, but they are mostly frequency dependent. The proposed solution is frequency independent. In addition, inherent signals may be utilized for protection purposes, since both instantaneous frequency and voltage values are estimated. This includes both positive and negative sequence voltages. The design has been simulated, and the simulation results are verified through experimental results.
	Photovoltaic Power System with Simplified Cascade Boost Choppers   By IIDA Shoji; UTSUMI Ryosuke; MASUKAWA Shigeo	[View]   [Download]
Abstract: Photovoltaic (PV) modules under different solar irradiances have generally the distinct maximum power points. In this paper, a circuit topology for obtaining the respective maximum powers from the above PV modules is investigated. Simplified double cascade boost choppers are proposed and a control scheme to derive the respective maximum output powers from individual PV modules is discussed. Furthermore, the Maximum Power Point Tracking controls on the starting operation, on the solar irradiance change and on the load fluctuation are confirmed by several experiments.
	Precise Digital Control Method with Sinusoid based Model for SinglePhase Utility Interactive Inverter with FPGA based Hardware Controller   By YOKOYAMA Tomoki; HAYASHI Kenta; TAKAMATSU Sayaka	[View]   [Download]
Abstract: In this paper, a new current control method for the utility interactive inverter based on deadbeat control with FPGA based hardware controller is proposed. Deadbeat control is one method to ensure the output voltage or current matches to the references at the sampling instant, so adopting this control law to the utility interactive inverter, the response of the system is much improved with small LC filter component compared with the conventional PI control, which results in the improvement of the cost performance of the inverter. Sinusoid based modeling approach was applied to derive the discrete model to the utility voltage and the inverter voltage, precise control accuracy can be derived. All the control circuit for the proposed current control method using voltage deadbeat control and PLL control with quasi-dq transformation are implemented in FPGA based hardware controller. The advantages and the disadvantage are discussed through simulations and experiments.
	Stationary Frame Voltage Harmonic Controller for Standalone Power Generation   By FRANQUELO Leopoldo; UNDELAND Tore; KULKA Arkadiusz; VAZQUEZ Sergio	[View]   [Download]
Abstract: The paper presents a new control scheme for voltage control of voltage source inverter (VSI) with LC output filter. Proposed high performance control scheme with use of stationary regulators can be used in UPS or standalone power generation where sine wave output voltage is to be maintained. The proposed controller is able to compensate voltage distortion from unbalanced and nonlinear loads, thus controlling negative and positive voltage sequence and its harmonics. For the control purpose only voltage measurement in required. Besides, the controller can be further used in distributed power generation where the parallel operation is desired. In order to improve the parallel operation and sharing any kind of distorting loads, the proposed controller allows adjusting the gain of selected harmonics required for proper harmonic sharing. The proposed scheme is fully appropriate for digital implementation of UPS systems where high quality AC output voltage is in importance. The diagram block of the proposed controller is shown together with some simulation and experimental results. Presented controller shows outstanding performance under nonlinear and unbalanced loads which uses selective harmonic compensators.
	Studies on a LV DC network   By ALBU Mihaela; CHIRILA Aurel; DEACONU Dragos; TOMA Lucian	[View]   [Download]
Abstract: In this paper, one application targeting a small-scale DC network supplying signal processing laboratory (personal computers, universal motors and other low-voltage, low-power loads) is proposed, in order to analyze the technical interconnecting possibilities of isolated power systems. As a first step, simulations using the already implemented network elements models in DIgSilent were performed in order to choose an optimal location of the generation units, considering restrictions related to available space, safety and future development. The next step was to develop mathematical models of the loads characteristics when each module is supplied with direct voltage, in order to further test direct DC supply of the laboratory. The paper is a consequence of the new approach oriented to innovative technologies for integrating dispersed and intermittent sources (DG) into distribution networks.
	Using the model of the solar cell for determining the maximum power point of photovoltaic systems   By HARTMANN Lucas	[View]   [Download]
Abstract: This paper proposes a technique for accelerating the convergence to the maximum power point of photovoltaic (PV) systems based on the model obtained from manufacturer's generator data. The influence of the temperature over the PV array performance is considered, and no measurement of solar radiation is required. No knowledge of the load model and no expensive sensor circuitry are necessary. The tracking speed is much faster than non model-based techniques at the expenses of an increase in the computational complexity. Simulation and experimental results are presented and demonstrate the feasibility of the proposed solution.