分布式电源与微网管控技术综述

分布式电源具有投资省、方式灵活、与环境兼容等特点,是实现新能源利用的重要组成。为了降低分布式电源的不利影响而使光伏发电单元、风力发电单元、负荷、储能装置和控制装置等构成的小型电网-微电网,微网满足电能质量和供电可靠性、安全性。微电网管控技术是微电网稳定可靠运行的关键技术。基于此,文中重点介绍风力和光伏等分布式发电技术,以及基于分布式电源的微网管理控制技术。探讨该领域的研究热点和发展前景。     

Wavelet-Based Islanding Detection in Grid-Connected PV Systems

Distributed power generation systems (DPGSs) based on inverters require reliable islanding detection algorithms (passive or active) in order to determine the electrical grid status and operate the grid-connected inverter properly. These methods are based on the analysis of the DPGS voltage, current, and power in time or frequency domain. This paper proposes a time-frequency detection algorithm based on monitoring the DPGS output power considering the influence of the pulsewidth modulation, the output LCL filter, and the employed current controller. Wavelet analysis is applied to obtain time localization of the islanding condition. Simulation and experimental results show the performance of the proposed detection algorithm in comparison with existing methods.     

A DSP- and FPGA-Based Industrial Control With High-Speed Communication Interfaces for Grid Converters Applied to Distributed Power Generation Systems

New energy concepts such as distributed power generation systems (DPGSs) are changing the face of electric distribution and transmission. Power electronics researchers try to apply new electronic controller solutions with the capacity of implementing new and more complex control algorithms combined with internal high-speed communication interfaces. Thus, it is possible to monitor, store, and transfer a large number of internal variables that can be sent online to local or remote hosts in order to take new set points of different generation units. With this objective, this paper presents the design, implementation, and test of an industrial multiprocessor controller based on a floating-point digital signal processor (DSP) and a field-programmable gate array, which operate cooperatively. The communication architecture, which has been added to the proposed electronic solution, consists of a universal serial bus (USB), implemented with a minimum use of the DSP core, and a controller area network (CAN) bus that permits distributed control. Although the proposed system can be readily applied to any DPGS, in this paper, it is focused on a 150-kVA back-to-back three-level neutral-point-clamped voltage source converter for wind turbine applications.      

并网型风力发电系统电压稳定研究现状

风力发电作为目前应用最广泛的新能源,其接入电力系统后对电网电压稳定的影响得到了人们的广泛研究。由于风力发电不同于常规能源发电,所以影响并网型风力发电系统电压稳定的因素也和常规电力系统范畴内影响电压稳定的因素有所不同。分析研究并网型风力发电系统运行特性,了解其电压失稳机理,进一步为保证系统电压稳定以避免发生电压崩溃提出相应的控制策略,是当今学术界的一个重要研究方向。文中对上述问题的相关研究成果进行了综述,并做了相应总结。     

Simulation von Spannungsschwankungen durch Windparks

Growing awareness for the relevance of renewable national energy sources stimulated a trend towards application of wind power plants for production of electricity in Austria the last years. Facing the standard development of areas with economic wind energy potential by 20 kV voltage level, grid companies as well as wind park owners are confronted with power quality questions as a result of increasing wind park power output. Using numerical simulation all interdependencies between the electrical grid and wind parks in consideration of characteristics of single wind power plants as well as the electrical grid can be studied.     

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...     

Vector Control of Front-End Converters for Variable-Speed Wind–Diesel Systems

This paper presents a novel power-balance control method for a wind–diesel generation feeding an isolated grid. The system is based on a variable-speed wind energy conversion system (WECS) connected to an ac load using a power converter. An energy storage system (ESS), connected to the ac load using an additional converter, is used to balance the power generated by the WECS with the load. In this paper, the vector control systems for both interfacing power converters are discussed; the control uses the WECS converter to regulate the ac load voltage and the ESS converter to regulate the power flow to achieve a power balance. A small signal model is used to design the control systems. Finally, the proposed control is implemented in a 2-kW experimental prototype and the experimental results are fully analyzed and discussed in the paper.     

Design of a Power Conditioning Unit for Nonlinear Source-Load Systems

This paper describes the development, design, and operation of an electronic device which performs dynamic matching between electric energy sources and their respective loads. This matching is achieved by monitoring the output power of the energy source and modulating a control signal which, in turn, regulates appropriately the operation of a source-load interface device. This device is characterized by a simple structure and an ability to continuously match the characteristics of the source to those of the load, for maximum power transfer, even when these characteristics are randomly time-varying. The device may be used with existing energy systems, without significant changes, and operates effectively even when the utility grid substitutes for the load. Its operation is described in terms of a configuration involving renewable energy sources, such as wind electric conversion systems and photovoltaic arrays, as the primary energy generators. The latter are attracting the growing interest of many investigators recently.     

基于最佳功率给定的永磁直驱同步风力发电系统控制策略研究

直驱型风力发电系统由于不需要增速箱,在风电场中得到广泛的发展和应用.该文研究了发电机和风机的特性分析,提出了基于最佳功率给定的最大风能控制策略,该方法通过对发电机进行闭环控制,使输出功率按照最优功率曲线进行输出,实现最大风能跟踪.并研究了永磁直驱风电系统的双PWM变流器控制策略;搭建了直驱型风电机组整体模型,该系统能够实现并风能最大功率跟踪及并网控制,仿真验证了控制系统的正确性.     

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.     

A Fault Tolerant Doubly Fed Induction Generator Wind Turbine Using a Parallel Grid Side Rectifier and Series Grid Side Converter

With steadily increasing wind turbine penetration, regulatory standards for grid interconnection have evolved to require that wind generation systems ride-through disturbances such as faults and support the grid during such events. Conventional modifications to the doubly fed induction generation (DFIG) architecture for providing ride-through result in compromised control of the turbine shaft and grid current during fault events. A DFIG architecture in which the grid side converter is connected in series as opposed to parallel with the grid connection has shown improved low voltage ride through but poor power processing capabilities. In this paper, a unified DFIG wind turbine architecture which employs a parallel grid side rectifier and series grid side converter is presented. The combination of these two converters enables unencumbered power processing and robust voltage disturbance ride through. A dynamic model and control structure for this architecture is developed. The operation of the system is illustrated using computer simulations.     

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.     

An Efficient Wind–Photovoltaic Hybrid Generation System Using Doubly Excited Permanent-Magnet Brushless Machine

With ever-increasing concerns on energy issues, the development of renewable energy sources is becoming more and more attractive. This paper first reviews both the wind power and photovoltaic (PV) power generation techniques and their maximum-power-point tracking (MPPT) methods. Then, a new stand-alone wind–PV hybrid generation system is proposed for application to remote and isolated areas. For the wind power generation branch, a new doubly excited permanent-magnet brushless machine is used to capture the maximum wind power by using online flux control. For the PV power generation branch, a single-ended primary inductance converter is adopted to harness the maximum solar power by tuning the duty cycle. The experimental results confirm that the proposed hybrid generation system can provide high efficiency with the use of MPPT.      

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。     

Real-Time Control System Adopted to Energy Storage for Smart Grid Low Wind Applications: A Part of Distributed Renewables in Smart City

In this paper, extensive efforts have been undertaken to design and develop a control system, which is incorporated with an energy storage device that can store energy from low-voltage renewable sources. The developed device acts as a storage element, which can be used to charge small-scale batteries, cellular devices, and other applications in remote places where the grid connection is not available. The circuit is developed using a case-by-case analysis. In order to solve the low output voltage problem, a bipolar junction transistor-metal oxide semiconductor field-effect transistor (BJT-MOSFET) based switch control technology with the Arduino microcontroller has been implemented. The developed control system is extremely efficient in charging batteries through a supercapacitor for low-voltage sources. In this research, a small-scale 200-W portable vertical axis wind turbine is used at a wind speed of 3 m/s. The result shows the efficiency of the proposed system as compared with the conventional systems. The proposed system can be an important tool of the latest distributed energy generation technology which is an important part of a smart city. Lastly, the limitations and future scopes of the development of the control device are discussed for the future barrier. An important future scope identified is to integrate the Internet of Things based mobile interface for remote monitoring for any kind of pandemic situation like COVID-19. Now, it is high time to get our smart city concept aligned with the post COVID pandemic situation and get us prepared smartly for similar future occurrences.     

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.     

风电储能系统能量调度策略研究

为了改善风电场发电的稳定性,抑制风电引起的电压波动与闪变,提高含风电电力系统的稳定性问题成为重要的研究内容,本文在简要介绍风电的特点的基础上,针对风电并网带来的电能质量及稳定性等问题,阐述了基于能量调度技术的解决方案,详细介绍了基于模糊理论＂最大-最小＂算法的调度系统控制器和系统其它主要部分的模型及仿真结果。控制器根据负荷用电量预测信息控制储能系统的充放电,不仅能有效抑制并网后电网的电能波动也能优化风电的发电质量。MATLAB仿真结果表明,风电储能系统能量调度策略和控制器是有效的,该系统能够有效减小风电场并网功率的波动。     

Power electronics as efficient interface in dispersed power generation systems

The global electrical energy consumption is rising and there is a steady increase of the demand on the power capacity, efficient production, distribution and utilization of energy. The traditional power systems are changing globally, a large number of dispersed generation (DG) units, including both renewable and nonrenewable energy sources such as wind turbines, photovoltaic (PV) generators, fuel cells, small hydro, wave generators, and gas/steam powered combined heat and power stations, are being integrated into power systems at the distribution level. Power electronics, the technology of efficiently processing electric power, play an essential part in the integration of the dispersed generation units for good efficiency and high performance of the power systems. This paper reviews the applications of power electronics in the integration of DG units, in particular, wind power, fuel cells and PV generators.     

Interfacing Renewable Energy Sources to the Utility Grid Using a Three-Level Inverter

This paper presents a novel approach for the connection of renewable energy sources to the utility grid. Due to the increasing power capability of the available generation systems, a three-level three-phase neutral-point-clamped voltage-source inverter is selected as the heart of the interfacing system. A multivariable control law is used for the regulator because of the intrinsic multivariable structure of the system. A current source (playing the role of a generic renewable energy source) is connected to the grid using a three-level inverter in order to verify the good performance of the proposed approach. Large- and small-signal d-q state-space averaged models of the system are obtained and used to calculate the multivariable controller based on the linear quadratic regulator technique. This controller simultaneously regulates the dc-link voltage (to operate at the maximum power point of the renewable energy source), the mains power factor (the power is delivered to the grid at unity power factor), and the dc-link neutral-point voltage balance. With the model and regulator presented, a specific switching strategy to control the dc-link neutral-point voltage is not required. The proposed controller can be used for any application, since its nature makes possible the control of any system variable. The good performance of the presented interfacing solution in both steady-state and transient operation is verified through simulation and experimentation using a 1-kW neutral-point-clamped voltage-source-inverter prototype, where a PC-embedded digital signal processor board is used for the controller implementation     

间歇式能源发电系统无功补偿技术的研究

针对间歇式能源发电系统的特点和无功需求,提出了将无功补偿与风力并网发电相结合的设计方案,通过计算得出了间歇式能源发电系统中电缆和变压器无功损耗.本文利用Mat-lab/Simulink搭建了具有无功补偿功能的并网变流器的仿真模型,并采用有功无功解耦控制和SPWM控制方法,补偿系统所需无功以及有效抑制动态电压波动.最后,仿真结果验证了风力并网变流器在向电网提供有功功率的同时也能够提供一定容量的无功功率,提高系统功率因数,有效抑制电网电压波动.