Warum Windenergie keine konventionellen Kraftwerke ersetzt und ein leistungsfähiges Übertragungsnetz benötigt

The amount of wind power installed in Austria has tripled over the year 2003. At present 430 MW are in operation and about 1000 MW of further projects are known. At the end of 2004 about 700 MW are assumed to be in operation. Due to the fluctuation of wind, the limited forecast possibilities and the resulting volatile generation, wind power plants cannot replace conventional power plants but may give an ecologically valuable contribution to the existing generation. Regarding the security of supply wind power plants cannot grant ongoing generation and supply all over the time. This results in the need for additional operation of conventional power plants (e.g., pump storage power plants) to provide the necessary real time balance between generation and consumption of electrical energy at any time (balancing energy). A powerful transmission grid is required for this interaction as well as for the transportation of generation surpluses from large wind parks to the consumers. This advantageous combination of a “wind and water” system cannot be fully exploited due to severe bottlenecks within the Austrian transmission grid. This article shall highlight the new challenges in the operation of the transmission grid and the control area of Verbund-Austrian Power Grid due to the wind energy. Furthermore, an integrated planning approach for the energy system, considering all aspects from generation, transmission and distribution is urgently needed.     

Kraftwerkseigenschaften von Windenergieanlagen hinsichtlich Kurzschlussverhalten, Engpass- und Blindleistungsmanagement sowie Spannungsregelung

The increasing number of wind turbines will lead to new demands for transmission and distribution system control in the years to come. In order to ensure a smooth integration of wind energy into an electrical energy system structure, wind farms will have to possess power plant properties and be able to provide ancillary services. The ENERCON concept offers solutions not only for critical situations, such as short-circuits and bottlenecks in the grid, but also for normal operation, such as reactive power management or voltage control. Wind farms will essentially function in a manner similar to conventional power plants and moreover offer additional advantages in the distribution grid.     

Contribution of synchronous condensers for the energy transition

In recent years a revival of rotating synchronous condensers could be seen all over the world. This trend is mainly driven by the introduction of enduring energy production. The change in energy mix is leading to the replacement of conventional energy production with synchronous machines by “low inertia” and “low thermal time constant” power park modules. Power park modules are represented by wind farms and registrable solar power plants. Compared to power park modules synchronous machines have a high thermal time constant and must therefore not be limited during short circuit events in its reactive power capability. Additionally, synchronous condensers have a natural mechanical inertia, which cannot be reached by modern power park modules. Therefore synchronous condensers complement power park modules for transmission upgrade projects and help to improve reliability, preserve future energy options and contribute to economic stability. Different design considerations are discussed.     

Battery Energy Storage to Strengthen the Wind Generator in Integrated Power System

The wind energy generation,utilization and its grid penetration in electrical grid are increasing world-wide.The wind generated power is always fluctuating due to its time varying nature and causing stability problem.This weak interconnection of wind generating source in the electrical network affects the power quality and reliability.The localized energy storages shall compensate the fluctuating power and support to strengthen the wind generator in the power system,in this paper,it is proposed to control the voltage source inverter(VSI)in current control mode with energy storage,that is,batteries across the dc bus.The generated wind power can be extracted under varying wind speed and stored in the batteries.This energy storage maintains the stiff voltage across the dc bus of the voltage source inverter.The proposed scheme enhances the stability and reliability of the power system and maintains unity power factor,it can also be operated in stand-alone mode in the power system.The power exchange across the wind generation and the load under dynamic situation is feasible while maintaining the power quality norms at the common point of coupling.It strengthens the weak grid in the power system.This control strategy is evaluated on the test system under dynamic condition by using simulation.The results are verified by comparing the performance of controllers.     

A Review of the State of the Art of Power Electronics for Wind Turbines

This paper reviews the power electronic applications for wind energy systems. Various wind turbine systems with different generators and power electronic converters are described, and different technical features are compared. The electrical topologies of wind farms with different wind turbines are summarized and the possible uses of power electronic converters with wind farms are shown. Finally, the possible methods of using the power electronic technology for improving wind turbine performance in power systems to meet the main grid connection requirements are discussed.      

A New Spin On Architecture

It?s your LegoLand building-block fantasy come to life. When the twisted tower in this rendering is completed in Dubai in 2010, each of its 80 floors will rotate independently around a central column that will house its elevator shafts, stairwells, and utilities. Sections of each floor, complete with cabinets, electrical wiring, and bathroom fixtures, will be preassembled off-site, hoisted up, and hung, intact, on the central column. In the gaps between each floor, wind turbines will spin; these and solar panels on the edges of each floor?s partially exposed roof will generate enough power to make the 420-meter-high rotating skyscraper independent of the energy grid. The curvy, statuesque beauty will house offices, a luxury hotel, apartments, and a few full-floor villas with space enough for residents to park their cars safely inside.     

A Secondary Voltage Control Strategy for Transmission Level Interconnection of Wind Generation

This paper addresses implementation issues associated with secondary voltage control in a doubly-fed induction generator based wind farm. The effects of different system parameters on the performance of the control are considered, namely the short circuit ratio of the interconnection and the inherent communication delay between the wind park and the remote bus. In addition, a strategy for allocation reactive power requirements to each of the generators within the wind park is proposed. The system is developed and simulated for a wind park consisting of six wind generators connected to a typical transmission system. The paper proposes an optimal tracking secondary voltage control method developed to achieve effective voltage regulation, enhance the network voltage profile and provide optimal reactive power compensation to the interconnected power system. The performance of the controller is compared with secondary voltage control at one selected bus, primary voltage control and the optimal voltage profile obtained from the optimal power flow analysis. The performance of the controllers is tested for steady state operation and in response to system contingencies, taking into account the impact of communication time delays and short circuit ratio (SCRs). Simulation results are presented to demonstrate the capability of the controllers to provide the desired reactive power compensation and voltage support to the electric power grid.     

电压骤降下双馈电机撬棒投切时刻对电网的无功功率影响

风力发电机规模和单机容量不断增大,电网对风力发电机之类的可再生能源并网有着极其严格的要求,其中最具挑战性的要求是低电压穿越,即在电网出现跌落时,要求风机在一定时间内不得脱网,直至发电机发出一定的无功功率帮助电网恢复。本文研究在电网出现大幅跌落时,通过控制撬棒投切的不同时刻,来讨论是否其投切时刻影响着系统从电网吸收的无功功功率,最终通过合理的投切时刻来最大程度上减少系统从电网吸收的无功功率,帮助电网更好的恢复。     

风光互补并网发电系统的PSCAD仿真设计

针对目前单一式离网型新能源发电系统的发电不稳定性及能源溢出浪费等问题,提出了一种风电与光电相结合的互补式并网发电系统的设计理念。利用风能与太阳能二者较强的互补性,解决传统单一式发电系统昼夜间歇性供电问题。同时,该发电系统采用并网式结构,可以将溢出的多余能源回馈给电网系统,实现系统发电量的有效利用,保证供电系统的长期稳定...     

大规模风电接入系统对电网谐波污染的仿真分析

基于甘肃酒泉地区大规模风电接入系统规划,通过测量统计的方法建立了风电场接入系统的谐波源模型,在电力系统不同运行方式下进行谐波潮流计算,并对比分析了现阶段和2015年千万千瓦风电接入系统电网谐波污染情况。计算结果表明,风电集中上网点谐波污染严重,谐波污染程度沿线路呈现衰减的趋势,离谐波污染源电气距离越远谐波幅值衰减越多,谐波次数也越来越少,且随着规划网架结构的不断增强,谐波污染源对电网的影响就越小。本文的研究将为电网规划设计和风电电能质量治理提供数据参考。     

Neue 1,5-MW-Windkraftanlage WT1566 — eine österreichische Entwicklung

The utilization of wind power allows the increase of the share of electricity supply by renewable energy sources. In a research and demonstration project which was funded by the European Commission a wind turbine with 1.5 MW rated power was developed. By optimizing the system components especially for sites with relatively low wind speed conditions and by choosing a high rated power it was attempted to reach fairly competitive electricity generating costs. A variable rate of revolutions per minute and pitch control yield to a maximum energy output. The generator is equipped with highly efficient power electronics using an IGBT (isolated gate bipolar transitor) inverter, thus assuring high efficiency with little harmonic distortions on the grid. Prior to this project a similar smaller wind turbine (600 MW) of the same design has been erected and put into operation. The 1.5 MW wind power plant has been successfully connected to the grid in November 1998.     

供变速风机使用的电力电子变流器

在风力发电系统中变速驱动方式的引入给系统带来了许多好处，但是变速风力发电机产生的电能与电网要求的标准不相适应，必须在发电机和电网之间安装电力电子变流器，才有可能将风力能源送入电网。文章主要介绍了在变速风力发电系统中使用的几种不同电力电子变流器的拓扑结构和它们在其它系统中的应用及目前的发展情况。     

Flexible thermische Kraftwerke für die Energiewende

System stability and security of supply are the main tasks which are increasingly challenging the electrical grid and its users, caused by the energy transition over the next decades. The paper describes the detail tasks in relation to the respective time scales. Conventional thermal power plants have been undertaking those tasks in the past and they will and need to undertake them also in the future. Detail topics as inertia, frequency stability, fast loading rates, and also the integration into forward-looking concepts as Power-to-Gas are highlighted and show the indispensable role of conventional thermal power plants and their consistent integration of energy transition.     

Multifunktionales Batteriespeichersystem

In the national research project “Multifunctional Battery Storage System (MBS)” open questions were answered concerning the technical feasibility and profitability of a grid-connected battery storage system using a vanadium-redox-flow battery in combination with the renewable power generation plants PV and small wind power (Sterrer et al., Multifunktionales Batteriespeichersystem—MBS-Endbericht. Industrielle Forschung im Rahmen der österreichischen Programmlinie Neue Energie 2020, 3. Ausschreibung, noch nicht veröffentlicht, 2013). The technical implementation and the demonstration operation of the pilot plant over a period of two years showed that the battery storage system is suitable for intelligent marketing of renewable energy as well as the provision of system services for grid stabilisation. However, the investigation of different operating strategies of the pilot battery-storage system, a large scale storage system and pooled PV/battery storage systems as virtual power plant for the participation at the energy trading market and energy reserve market showed that all operation strategies being considered in this study may not be profitable in foreseeable future. However, if the costs of the battery storage system can be reduced to about 250 €/kWh until the year 2030, the application of the vanadium-redox-flow battery in particular in large-scale storage plants (e.g. 10 MW, 100 MWh) for the participation at the energy reserve market seems realistic.     

Test Bench for Grid Code Simulations for Multi-MW Wind Turbines, Design and Control

The hardware configuration and control methodology for a test bench for power grid simulations for multi-MW wind energy applications are described. The variable voltage is generated using two (four in the final stage) medium voltage, three-phase, three-level voltage source converters with press-pack insulated gate bipolar transistors and a specially designed step-up transformer. This system differs fundamentally from known grid simulation test benches that almost always use switched inductances. Simulation results using MATLAB/Simulink and measurements as well as constraints to the system are discussed.      

Steady as she blows [wind power, energy storage]

Power electronics and exotic energy storage devices are making wind power steady enough to compete with conventional electricity sources. Systems based on advanced power electronics and energy storage devices are massaging and managing power flows from wind turbines, enabling them to contribute to electricity grids without putting those grids at risk. Not only are the technologies making wind power more palatable to grid operators, they are even making it possible for engineers to finally harness wind energy's tremendous potential in wind-swept, remote locales. This article discusses the power electronic and energy storage technologies used in wind power.     

Wind Speed Estimation Based Sensorless Output Maximization Control for a Wind Turbine Driving a DFIG

This paper proposes a wind speed estimation based sensorless maximum wind power tracking control for variable-speed wind turbine generators (WTGs). A specific design of the proposed control algorithm for a wind turbine equipped with a doubly fed induction generator (DFIG) is presented. The aerodynamic characteristics of the wind turbine are approximated by a Gaussian radial basis function network based nonlinear input-output mapping. Based on this nonlinear mapping, the wind speed is estimated from the measured generator electrical output power while taking into account the power losses in the WTG and the dynamics of the WTG shaft system. The estimated wind speed is then used to determine the optimal DFIG rotor speed command for maximum wind power extraction. The DFIG speed controller is suitably designed to effectively damp the low-frequency torsional oscillations. The resulting WTG system delivers maximum electrical power to the grid with high efficiency and high reliability without mechanical anemometers. The validity of the proposed control algorithm is verified by simulation studies on a 3.6MW WTG system. In addition, the effectiveness of the proposed wind speed estimation algorithm is demonstrated by experimental studies on a small emulational WTG system.     

Inherit the wind

In December 1991, Britain's first commercial wind farm at Delabole, Cornwall was connected to the local grid. The wind farm consists of ten Danish wind turbines with a rating of 400 kW each and is capable of generating enough electricity to provide the needs of 3000 homes; this scheme was one of nine chosen for NonFossil Fuel Obligation (NFFO) contracts in 1990. The author discusses the wind energy potential of the UK, and the environmental benefits of the wind power. The author describes the technology involved in horizontal axis wind turbines. The economics of wind power and its integration into the electricity grid is also discussed     

风力发电机组功率曲线分析研究

在风电机组将风能转换为电能所经历的三个环节基础上,以内蒙古赤峰市某一风电场的风电机组为研究实例,对影响风力发电机组功率曲线的主要因素进行了简要研究,并得出了影响风电机组功率的重点因素为发电机变频控制性能的结论。     

New Fuzzy Control Strategies Applied to the DFIG Converter in Wind Generation Systems

This paper presents new fuzzy control strategies which may be applied to the converter connected to the rotor of doubly fed induction generators (DFIG) composing a variable speed wind generation system connected to a real electrical grid. The fuzzy control proposed strategies are of the type supervised “look-up-table”. The performance of these intelligent controllers are compare with the fixed parameters PI controllers for fault ocurrence in the power system. The fuzzy controllers are supposed to better the transient performance of the electrical power system as compared with the conventional PI controllers. The obtained results from simulation studies have of the fuzzy controllers. To formulate the simulation studies an equivalent mathematical model of a significant number of wind turbines was implemented using the MATLABTM software packcage.