微风电与光伏相结合的分布式发电系统

利用垂直轴微风发电技术,研发了微风电与光伏相结合的分布式发电系统,实现了昼夜不间断发电。垂直轴微风发电比水平轴风力发电系统,具有风力资源利用率高,年发电量多等优点。本文对分布式发电系统不同配置及适用范围进行了论述,为风力资源属于低风速的区域提供了一种可再生能源利用的新技术,尤其适合无电人口地区推广应用。     

Reactive power pricing in power markets: a comprehensive review

ABSTRACT

Reactive power is one of the main characteristics that play a major role in power systems. When reactive flow is inadequate, the power system is confronted with voltage collapse and more than enough reactive power production follows the circulation in the network and consequently the occupation of power lines. On the other hand, power market evolves from centralised and vertically integrated structure to a competitive environment. The reactive power market is different from energy market and like others such as spinning reserve, frequency control and power system stabiliser is taken in the category of the ancillary service market. This paper reviews various mechanisms for pricing of reactive power in both levels of transmission and distribution (T&D) system. Additionally, the cost paid for reactive power service in the presence of distributed energy resources is analysed because of their high penetration in the power system, especially in distribution level.     

Assessment of electricity generation by wind power in nine costal sites in Malaysia

In this article, the wind power potential in Malaysia is examined. Hourly wind speed data for nine sites in Malaysia are used to optimally design wind power systems for remote housing electrification. These nine sites are Bintulu, Kota Kinabalu, Kuala Terengganu, Kuching, Kudat, Mersing, Sandakan, Tawau and Pulau Langkawi. The designed wind power systems are supposed to supply hourly load demand 6.13?kWh/day, 0.52?kW peak with 1% loss of load probability. The unit cost of the energy produced by each system is calculated and compared to the unit cost of the energy produced by a standalone photovoltaic (PV) power systems and a diesel generator power systems. The results show that the average unit cost of the energy produced by a wind power system in Malaysia is 1.6–7.29?USD/kWh while it is 0.35–0.5?USD/kWh and 0.27–0.30?USD/kWh for PV power system and diesel generator power system, respectively. Based on this, the use of wind power systems as standalone systems is not recommended for the selected sites.     

The performance of small wind power generation systems on super high-rise buildings

This study was conducted on the application of small wind power generation systems to super high-rise buildings. Environmental factors considered in the application of small wind power generation systems to super high-rise buildings are the wind speed, wind direction, maximum instantaneous wind speed, air flow turbulence, and noise and vibration in the target regions and buildings. According to the results of fluid dynamics (CFD) simulations, square or rectangular shaped super high-rise buildings create turbulent air flows occurred uniformly on roofs and the sides of entire buildings, from the lowest floor to the highest. High wind speeds occurred on the sides of buildings. Few turbulent beds occurred in the case of round or triangular shaped super high-rise buildings indicating that round and triangular shapes in plan are advantageous for the application of wind power systems. Electric power generation was measured in mock-up tests. When they were installed in a row, small wind power generation systems met the standards for noise and vibration from continuous rotation indicating that they would cause little damage to buildings through their noise and vibration.     

风电火灾原因及防火对策

通过对风能特点与消防关系的分析,找出引发风电火灾的原因,如雷击、电气、机械故障、人为因素等,提出增设固定报警灭火系统、防火分隔控制、加强消防技术研究、制定相关标准、加强日常防火监督等预防风电火灾的对策.     

Modular multi-level converter-based DFIG wind power system with MMC-STATCOM

ABSTRACT

Transmission and distribution conversion operation, voltage, current magnitude variation and time-to-time power flow change through grid are the major issues in power system. Variable wind energy system is more popular for power generation through conventional converters and hence harmonic reduction is very less in these converters. In this paper, 9?MW modular multi-level converter-based DFIG wind energy power system parameters are compared with 9?MW DFIG systems using conventional converter. DFIG is operated in four mode condition with proper back-to-back power electronic converters and controllers. In power electronics, the modular multi-level converters are more advanced for reducing transients, peak response oscillations and improving the efficiency of the system. A five-level MMC has been applied in back-to-back converter with phase disposition (PD) PWM technique for DFIG wind system of the same rotor side controller and grid side controller. A conventional converter-based DFIG wind energy system is replaced with five-level MMC-based system with level shift PD-PWM technique. The impact of MMC on DFIG wind energy system is reduced voltage and current harmonics fast settling time compared to conventional converter-based DFIG system. The above MMC DFIG power system voltage is balanced at fault condition with MMC-STATCOM.     

基于地震荷载作用下的风力发电塔的地震响应分析

基于地震荷载的作用,应用大型有限元软件FINAL,研究不同结构参数的风力发电塔在地震荷载作用下的地震响应,以及比较它们之间的差异,进而得出改变风力发电塔的结构参数对于地震响应的影响规律.以二维风力发电塔模型为例,建立4个不同参数的模型,首先进行模态分析,计算出每个模型的固有频率,通过比较固有频率得出结论,并对其进行比较分析.然后对4个模型施加1993年北海道西南海面桥地震波形,分析比较它们在此地震波形作用下的地震响应值,进而得出不同的结构参数对地震响应的影响规律.     

Simulation and assessment of power variations from wind arrays during local storms

Little attention has been paid to the development of control practices for utilities with power variations resulting from wind generation. One of the reasons is that little information is available on wind power variations from wind power arrays. This study demonstrates that severe operating problems can be caused by local storms in utilities with wind penetrations exceeding 5% of the utility's capacity. It is expected that future wind generation can comprise up to 15% of a utility's capacity which points to an even greater need for the development of control practices. The study was carried out by simulating wind power variations from various configurations of MOD-2 (with a capacity of 2 MW) wind turbine arrays during local storms. An existing wind data set collected at 27 meteorological measurement sites located in a square area of 128 km on a side was used to study the effects of spatial and temporal wind speed variations during storms. Wind power variations of individual units, arrays, and a series of multiple arrays are presented. It is shown that wind power variations of single arrays will be above 60% of capacity over a period of 15 min. Widely separated arrays reduce power variations but do not eliminate a high percentage of capacity changes in a 15-min period. Cyclic variation on a single unit due to turbulence is large as a percentage of capacity but does not produce large power variations as a percentage of multiple array power capacity.     

Wind power in Australia

This paper reviews the present status of wind power in Australia, the barriers to its further development, and the policies needed for overcoming those barriers. Unlike bioenergy or solar electricity, wind power does not need significant funding for R, D and D in Australia, but rather needs market/industry development policies. The major barrier is the political power of the coal and nuclear industries and NIMBY groups, which have disseminated exaggerated and misleading claims about the environmental impacts and alleged technological limitations of wind power, fostering opposition to wind power by the Federal Government. This paper examines critically one of the main claims, the fallacy that wind power, as a so-called 'intermittent' source, cannot be used to substitute for base-load power from coal. Continued expansion of the wind industry in Australia would need an extension of the Mandatory Renewable Energy Target, reinforced by the implementation of a carbon tax or emission permits with cap and trade.     

离网风电-网电互补供电的载荷模拟试验研究

基于离网风电-网电互补供电试验研究,设计了以计算机编程调制载荷的磁粉制动器加载装置,并在搭建的试验平台上,试验研究了加载装置模拟实际载荷特性,以及互补双电源向负载供电的切换控制技术.试验结果表明,加载装置的响应速度和加载精度可真实反映模拟实际载荷特性,互补双电源的切换控制技术可靠、稳定,提高了风能利用率.     

A power electronics based power shedding control for wind/diesel systems

The use of power shedding (or dump load) control in wind-diesel systems represents a method to ensure stability of the electrical network or to maintain a minimum load on the diesel(s). One approach to dissipate excess power is the use of an electronically controlled electrical load. This paper describes a simple, effective, low cost, and reliable power shedding control system that was designed and built as part of the University of Massachusetts Wind/Diesel System Simulator. The power electronics design, which is based on pulse width modulation, requires only one active switching device, and a single resistive element. In its present form, the capacity of the device is 10kW. Scaling, however, to a larger capacity should not present significant problems. As described in the paper, tests undertaken with the dump load control show that it can successfully maintain grid frequency, has acceptable harmonic distortion, and can ensure a minimum load on a diesel generator. In addition, the dynamic response of the control has been found to be acceptable.     

Clean energy transition in the Turkish power sector: A techno-economic analysis with a high-resolution power expansion model

The Turkish power sector achieved rapid growth after the 1990s in line with economic growth and beyond. However, domestic resources did not support this development and therefore resulted in a high dependency on imported fossil fuels. Furthermore, the governments were slow off the mark in introducing policies for increasing the share of renewable energy. Even late actions of the governments, as well as significant decreases in the cost of wind and especially solar technologies, have recently brought the Turkish power sector into a promising state. A large-scale generation-expansion power-system model (TR-Power) with a high temporal resolution (hours) is developed for the Turkish power generation sector. Several scenarios were analyzed to assess their environmental and economic impacts. The results indicate that a transition to a low-carbon power grid with around half of the electricity demand satisfied by renewable resources over 25 years would be possible, with annual investments of 3.97–6.88 billion in 2019 US$. Moreover, TR-Power indicates that the shadow price of CO₂ emissions in the power sector will be around 17.1 and 33.8 $/per tCO2 by 2042, under 30% and 40% emission reduction targets relative to the reference scenario.     

Controlling power output of solar chimney power plant according to demand

ABSTRACT

The solar chimney power plant (SCPP) is a simple solar thermal power plant that is capable of converting solar energy into thermal energy in the solar collector. In the second stage, the generated thermal energy is converted into kinetic energy in the chimney and ultimately into electric energy using a combination of a wind turbine and a generator. The numerical simulations were performed for the geometry of the prototype in Manzanares, Spain. Using computational ?uid dynamics (CFD) techniques; we have simulated a two-dimensional axisymmetric model of a SCPP with the RNG k-ε turbulence. In this model, the discrete ordinates (DO) radiation model was implemented to solve the radiative transfer equation, using a two-band radiation model. The main objective of this work is to explore dynamic control over plant power output. We have presented a technique to control the power output of the solar chimney power plant, in order to deliver power according to specified demand patterns. In order to present this, the reference plant model was modified to include a secondary and tertiary collector roof under the existing main collector. In terms of base load electricity generation, the inclusion of a secondary and tertiary collector roof produces good control over plant output.     

Power quality improvement of grid-connected wind energy system using facts devices

ABSTRACT

The increased penetration of wind power into the grid will save the fossil fuels and reduce the impact on the environment; however, it also presents many challenges to power system operation and control, system stability and power quality. In this paper, the use of static compensator (STATCOM) with battery energy storage system (BESS) is to enable smooth and the proper integration of wind energy system to the grid is taken as the main objective. This work presents a novel controller for an integrated STATCOM-BESS for grid-connected wind energy system. The simulation of the proposed system is done in Simulink with hysteresis current controlled pulse width modulation-based controller, which is in the IEC 61400-21 standard. It is observed that the STATCOM with BESS, operated with the specified controller, provides reactive power support, good harmonic mitigation as well as maintaining the source current the voltage without any phase angle difference. The experimental setup composed of Matlab-dSPACE DS1104 interface for generating the gate pulse, isolation and gate driver circuit, and the three-phase inverter is created and the system is tested for various combinations of R load and R-L load, and the measurements are recorded using FLUKE 434 energy analyser.     

Design of a robust controller for doubly fed induction generator to damp low frequency oscillations in emerging distribution systems

Emerging distribution systems accommodate a large number of dynamic devices such as distributed energy resources, their controllers and other smart devices. Complex interactions among these dynamic devices may result in a number of instability issues. One of the important instability concerns is the small signal instability caused by oscillatory modes with lower values of frequency and damping ratios. In such cases, a suitable control methodology must be applied to ensure the stability of an emerging distribution system. In this paper, a robust control methodology for a doubly fed induction generator (DFIG) is proposed for the enhancement of system stability. The impact of active and reactive power of the DFIG on a low damped mode is assessed. The effectiveness of the controller is tested in an IEEE 43 bus distribution system with distributed generation units. Results show that the proposed robust controller for the DFIG can support damping of critical modes.     

基于贯流式发电理念的高楼雨水发电新工艺

介绍了高楼雨水发电的工作原理,通过模型设计及理论计算分析,建立了一套高楼雨水发电工艺体系,并对该体系包含的雨水收集、贯流式发电、储电和智能控制供电三个部分进行了阐述,分析了该工艺的创新点和可行性,以促进其推广应用。     

Uncertainty in estimating renewable energy utilisation potential: a case of solar thermal power generation in India

Estimation of renewable energy utilisation potential is important for identification of niche areas and prioritisation amongst different options. However, large variation in the potential estimates has been observed in different studies for the same renewable energy technology. This study is an attempt to analyse such a variation in the estimated potential for solar thermal power generation in India. From the analysis of three studies, it is found that the values of input parameters and the assumptions made substantially affect the estimated potential. The estimates of the utilisation potential depend upon the categories of wastelands selected, the chosen values of threshold DNI and wind speed as well as the criteria used for allocating suitable wastelands between solar photo-voltaic (PV) and thermal power generation. It is therefore critically important that reported values of renewable energy utilisation potential be interpreted and used with full cognisance of assumptions made and input parameters used in estimation.     

谈风电场升压变电站电气二次设备选型与安装

分析了当前风力发电变电站二次设备选型和安装中存在的问题,结合质量管理的相关理论,提出了解决对策,以期有效地提高电力系统经济性以及变电站安全稳定运行能力。     

CAARC高层建筑标准模型层风荷载谱数学模型研究

用风洞试验方法在B、D两种地貌下研究了CAARC高层建筑标准模型在不同高度处的顺风向和横风向风荷载的功率谱特性和相干特性。结果显示:不同高度的无因次风荷载功率谱密度具有较好的一致性;在顺风向,不同高度风荷载间的相干特性显示出指数式的衰减规律;在横风向,风荷载在漩涡脱落频率附近有很强的相关性,相干函数值接近于1。根据风荷载沿结构高度变化的特征,进一步采用拟合方法确定了各层风荷载的功率谱密度和层间荷载相干函数的经验公式,建立了层风荷载谱数学模型,并给出了以此为基础计算标准模型风振响应的计算流程。将按照本文模型计算得到的广义力功率谱与高频底座力天平试验的结果作比较,结果吻合较好,证明了本文所提出模型的正确性。     

Wind turbine power curve estimation based on cluster center fuzzy logic modeling

Wind energy applications and turbine installation at different scales have been increased for last decade. Technically wind turbine capacity has been improved at high levels. However, electricity could not be generated at all stages of wind speed and so there are some limits related to cut-in and cut-out data. One of the main problems in wind engineering is to estimate output data of wind turbines depends on wind speed and system values. Wind speed problematic values, that are less than cut-in and greater than cut-out, take the most important role for estimating wind power curve models. All wind turbines have different cut-in and cut-out limits and generating of electricity could be achieved in a certain interval that could be called as affective interval. Fuzzy logic that is a new and novel verbal logical approach has many applications in the field of engineering. Cluster center fuzzy logic modeling is also a new and the effective method in this scientific area. In this paper, the first power curve of a wind turbine is modeled by least square methodology. After that depending on the fuzzy logic approach a new application is realized. It is seen that, this curve type could be well represented and modeled by the clustering center fuzzy logic modeling than classical least square methodology. It is estimated that four or five cluster centers are enough for representing wind turbine power curve by running proposed method.