Towards an overall simulator for a synchronous wind energy system

The amount of electrical energy obtained from renewable sources, specially wind energy, is rising quickly. The interface of this distributed generation with the electrical network will have soon an important influence on control, power quality and voltage stability issues of the whole energy net. In order to be prepared to that change it is necessary to simulate, with a sensible accuracy, the transient events, which happen during normal operation or during faults, and have influence in either net or inner variables. So in this way, it is important to model a wind energy system, taking into account every subsystem that have a significant influence over the transient behavior of the compound system. Some important and recent papers are oriented to analyze the stability [1] and the power quality of the wind systems [2]. In the first one, a doubly fed generator is analyzed from an electrical stability point of view; and in the second one the RMS values of the main electrical variables have been simulated in an overall wind energy system. An interesting paper describing the transient problems in relation with the grid integration of wind turbines can be seen in [3]. In this paper, as a preliminary design of an overall simulator, a variable speed system with a wound rotor synchronous generator is analyzed and a connection of the windmill with a variable wind is simulated.The authors are thankful to the support from the Caja de Ahorros del Mediterraneo (BECA-CAM predoctoral 2003, a grant conceded to the first author). This research is partially supported by the Consejeria de Educación y Ciencia de la Comunidad Autónoma de la Región de Murcia (Project Séneca 2002: PC-MC/3/00074/FS/02)

Evaluation of leakages effects in the water supply system of Moratalla (Spain). Póster

One of the risk management requirements is the assessment of the effect of each kind of possible failure. In water supply systems, the most common failures are the pipe leakages. Most leakages can be modelled as orifices in a pipe [1]. At this paper, a leakage pattern is defined for each of the 300 pipes in Moratalla’s water supply system. That leakage pattern is defined as an orifice whose diameter length is 1/10 of the pipe diameter. Epanet-Octave is a GNU Octave wrapper that makes easy and vector oriented the use of EPANET ToolKit. Epanet-Octave library has been used to carry out a simulation for each pipe which may have a leakage. Each simulation lasts a whole simulated day to include leakage effects for the different pressures and demands that happen during the day. Then, the results are summarised by using an index which weights the negative effect of the leakages. Usually leakages are evaluated mainly by the energy waste in pumping that water [2-3]. In this case, the suggested index accounts for leakage flow rates, water quality deterioration and service deterioration. Leakage flow rates effects are included through the maximum leakage flow rate (in time) and its average value, which in this case is proportional to the energy cost used in other works as the system distributes the water from the reservoirs to customers by gravity. Water quality deterioration is evaluated by the presence of negative pressures around the orifice. Finally, service deterioration is measured through the water that would be supplied below the regulated minimum pressure. This weighted index, which is shown in figure 1, can be used, together with other non-hydraulic factors like pipe-age or pipe-material, to prioritise the maintenance and even the replacement of pipes according to a risk management strategy

Modelización hidrodinámica y bioquímica de la generación de sulfuros en la impulsión de saneamiento de "Las Gaviotas" (Murcia). Reducción de sulfuros mediante inyección de aire.

[ESP] La generación de sulfuro de hidrógeno en las impulsiones de saneamiento es causada por la reducción microbiana de sulfato presente en el agua residual a sulfuro bajo condiciones anaerobias. El sulfuro de hidrógeno es el causante principal del mal olor y la corrosión en estructuras de saneamiento. Se ha diseñado un modelo hidrodinámico y bioquímico para tratar de cuantificar la producción de sulfuro en impulsiones de saneamiento con grandes tiempos de retención y predecir puntos sensibles que puedan generar molestias a la ciudadanía o problemas estructurales a la propia red. El objetivo de la inyección de aire en las impulsiones es garantizar ambientes aerobios en la conducción y facilitar la eliminación de sulfuros. [ENG] The release of hydrogen sulfide from sewers could cause corrosion problems in the sewer facilities, as well as odor issues in its surrounding areas. This gas is formed, mainly, in the force mains, where water has a high retention time and it becomes anaerobic. Therefore, the sulfates are reduced to sulfides. The hydraulic and biochemical computer model that is presented in this paper simulates the sulfide production and finds critical points in the force main. The model aims also to evaluate different amounts of air injection in order to maintain aerobic conditions for reducing sulfide generation.Este trabajo está financiado con fondos de la Entidad de Saneamiento de la Región de Murcia (ESAMUR) y de la cátedra HIDROGEA de la UPCT formando parte del convenio “Estudio en Prototipo de Inyección de Aire en Impulsiones de Aguas Residuales Urbanas para la Eliminación de Olores”

Evaluating energy recovery potential in Murcia's water supply system

Murcia is the 7th most populated city in Spain. Its water supply system is extensively monitored through a large number of pressure gauges and flow meters. Murcia’s water supply network is fed from distribution reservoirs at enough elevation to avoid needing pumping stations for most of the city districts. Hydraulic resources have been evaluated throughout the water supply system. Besides the pressure reducing valves, where the assessment is quite straight forward [1], District Metered Areas (DMA) inlets have been evaluated. In these areas despite the hydraulic resources are not as great as in pressure reducing valves locations, their location is quite convenient. Actually, these positions are located inside the city, therefore making easy to use the produced energy in municipal self consumption or to provide facilities to the citizens. In order to perform such evaluation, a detailed model of the water supply network has been implemented in EPANET parting from a GIS model. The first step of the evaluation has consisted in the optimizing and validation of the model. Initially, the model was reviewed by comparing pressure and flow rate measurements in the main pipes. Then, an extensive experimental campaign was designed. In that campaign valves were switched so that each day a set of District Metered Areas (DMA) have just one metered inlet or at the most a very short number of metered inlets, whereas having a set of pressure measurements within the DMA. The obtained data was used to minimize errors in pressure time series, optimising roughness of the main pipes through Levenberg/Marquardt BFGS algorithm using EPANET ToolKit through Epanet-Octave [2]. Important roughness proposed changes tended to be located surrounding particular points, where errors in the GIS were located (mainly wrong diameter assignement). After patching all the errors the algorithm eased to localise, model errors were mostly below measures uncertainty, and therefore, the model was considered validated. Then, the hydraulic potential at the DMAs inlets has been evaluated by tracking the “instantaneous” minimum pressure and head within each DMA, as well as the flow rate entering the DMA. So that, the maximum head and the range of flow rates is established for the turbine. At the moment, once that all of these potentials have been assessed, a turbine prototype is being designed

Proposals of a procedure to asses Pollutographs. Application to Murcia's Combined Sewer Overflows (CSOs). Póster

Directives 91/271/EEC and 93/481/EEC set norms regarding the management of Combined Sewer Overflows. European Commission monitors the implementation status and implementation programmes. In fact, during the year 2019 all the utilities should be able to quantify the pollution spilled during storm events. And afterwards, plans have to be developed in order to reduce the impact of such events. In this paper, we proposed a method to estimate the transported pollution during events as well as to serve as a tool for developing plans to lessen the corresponding pollution. The procedure is divided into three steps: A. Periodical measurements of all relevant pollutants, e.g. total suspended solids and chemical oxygen demand, in wet and dry weather. Such pollutant “concentrations” are correlated with the turbidity, updating the relation among them [1]. B. Continuous measures of the turbidity. Turbidity is continously register in the sewer areas near overflow spillways. Turbidimeters are a very convenient equipment for this purpose [2]. Actually, it is reliable, its measures are very correlated with the total suspended solid concentration and its maintenance is easy. In this way, combining A. and B. turbidity measures provide us a real-time estimation of the pollutant concentration. on real time. C. Assesment of each catchment hydrograph. Depending on the available data, this step could be based on a design, a measured or a simulated hydrograph. In order to apply this methodology to Murcia’s Combined Sewer System, we have used simulated hydrographs based on real measured rainfall. Murcia’s utility has developed a calibrated SWMM model, and therefore, using the rainfall data, it is possible to estimate hydrographs for all the relevant points of the system. D. Estimation of each catchment pollutograph. Combining the pollutant concentration, estimated in the previous steps, with the hydrographs, we can asses how the mass of pollutants are transported. This information allows us to comply with EU Directives, but it will also be useful to design Murcia’s strategy to minimize environmental impacts

Numerical Simulations And Laboratory Measurements In Hydraulic Jumps

Hydraulic jump is one of the most extended and effective mechanism for hydraulic energy dissipation. Usually, hydraulic jump characteristics have been studied through physical models. Nowadays, computational fluid dynamics (CFD) are an important tool that can help to analyze and to understand complex phenomena that involve high turbulence and air entrainment cases. Free and submerged hydraulic jumps with Froude numbers from 2.9 to 5.5 are studied in a rectangular channel downstream a sluice gate. Velocity measurements with different flow rates are carried out by using Acoustic Doppler Velocimeter (ADV) and Particle Image Velocimeter (PIV) instrumentations. In this paper, laboratory measurements are used to calibrate and to validate open source and commercial CFD programs. Air-water two-phase flows are considered in the simulations. The closure problem is solved by using different turbulence models. Water depths, hydraulic jumps lengths, velocity profiles and energy dissipation rates are compared with laboratory measurements and other referenced results

Application of ramp limitation regulations for smoothing the power fluctuations from offshore wind farms

This paper deals with the smoothing regulation strategies for reducing the effects of the wind farm power fluctuations. Concretely, realistic available power is obtained from an aggregated simulator of an offshore wind farm, developed and validated in previous papers. Being curtailed the power through positive ramp limitation and through a delta constraint linked with a negative ramp limitation. Then, the smoothing of the fluctuations is compared for an equivalent energy cost. Showing the reduction in the reserve requirements and ramping rates the power system needs for compensating them.The financial support provided by “Junta de Comunidades de Castilla-La Mancha”—PBC08-0275-3945— and “Ministerio de Educación y Ciencia” —ENE2006-15422-C02-01/ALT and ENE2006-15422-C02-02/ALT— is gratefully acknowledged

Estudio experimental de bloques de impacto trapezoidales

[ESP] La misión principal de las estructuras disipadoras de energía en grandes presas es reducir el tamaño y, por tanto, el coste de los cuencos disipadores de energía. Con ellas se consigue un acortamiento de la longitud del resalto hidráulico, limitando, así, la erosión o socavación a pie de presa y su posible vuelco. El objetivo de este trabajo es la realización de un contraste teórico-práctico con otros estudios realizados por diferentes autores sobre estructuras disipadoras de energía. [ENG] The main aim of energy dissipators structures at large dams is to reduce the size, and thus the cost of stilling basins. Such reduction is obtained by shortening of the hydraulic jump length, in this way erosion in the dam base is limited as well as its own spill. The target of this research is the attainment of a theoretical and practical contrast with other research results which have been carried out by different authors about energy dissipative structures.Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT), Escuela Técnica Superior de Ingeniería Agronómica (ETSIA), Escuela Técnica Superior de Ingeniería Industrial (ETSII), Escuela Técnica Superior de Arquitectura y Edificación (ETSAE), Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas (ETSICCPIM), Facultad de Ciencias de la Empresa (FCCE), Parque Tecnológico de Fuente Álamo (PTFA), Vicerrectorado de Estudiantes y Extensión de la UPCT, Vicerrectorado de Investigación e Innovación de la UPCT, y Vicerrectorado de Internacionalización y Cooperación al Desarrollo de la UPC

Validation of a double fed induction generator wind turbine model and wind farm verification following the Spanish grid code

Wind turbine manufacturers are required by transmission system operators for fault ride-through capability as the penetra-tion of wind energy in the electrical systems grows. For this reason, testing and modeling of wind turbines and wind farmsare required by the national grid codes to verify the fulfillment of this capability.Therefore, wind turbine models are required to simulate the evolution of voltage, current, reactive and active powerduring faults. The simulation results obtained from these wind turbine models are used for verification, validation and cer-tification against the real wind turbines measurement results, although evolution of electrical variables during the fault andits clearance is not easy to fulfill.The purpose of this paper is to show the different stages involved in the fulfillment of the procedure of operation forfault ride-through capability of the Spanish national grid code (PO 12.3) and the ‘procedure for verification, validation andcertification of the requirements of the PO 12.3 on the response of wind farms in the event of voltage dips’. The process hasbeen applied to a wind farm composed of Gamesa G52 wind turbines, and the results obtained are presented.The authors would like to thank GAMESA for the technical and financial support. The financial support provided by ‘Junta de Comunidades de Castilla-La Mancha’ (PEII10-0171-1803) and ‘Ministerio de Ciencia y Innovación’ (ENE2009-13106) is gratefully acknowledged

Wind Power Variability and Singular Events

Examples of the different events affecting wind power fluctuations are shown.The behaviors and the responses of the Spanish power system and wind power plants experiencing such events were analyzed. Examples presented in this chapter show that some of the wind power integration issues are related to low-voltage ride-through. They are solved through strict grid code enforcement. Other solutions to manage the reserve power generation and the wind power fluctuations are also very important in order to achieve high levels of wind power penetration. In the Spanish case, this could require increasing the availability of dispatchable and fast-start power plants, as well as increasing wind power plant participation on supporting the power system by providing voltage control, inertial emulation, frequency control, oscillation damping, or updated voltage ride-through capabilities.Comment: Chapter of the Book 'Wind Power' (eBook (PDF) ISBN: 978-953-51-6418-0