A stochastic framework for uncertainty analysis in electric power transmission systems with wind generation

The purpose of this work is the analysis of the uncertainties affecting an electric transmission network with wind power generation and their impact on its reliability. A stochastic model was developed to simulate the operations and the line disconnection and reconnection events of the electric network due to overloads beyond the rated capacity. We represent and propagate the uncertainties related to consumption variability, ambient temperature variability, wind speed variability and wind power generation variability. The model is applied to a case study of literature. Conclusions are drawn on the impact that different sources of variability have on the reliability of the network and on the seamless electric power supply. Finally, the analysis enables identifying possible system states, in terms of power request and supply, that are critical for network vulnerability and may induce a cascade of line disconnections leading to massive network blackout.     

风力发电技术探讨

近年来随着可持续发展的需要、技术的进步、环境保护意识的增强和有关政策的制定,风力发电技术有了长足的进步,风电产业已发展成为每年有数十亿美元的世界性大市场,世界总装机容量已超过13000MW,近几年更是以超过30%的速度增长,是发展最快的一种新能源技术。随着风力发电技术的推广、建设规模的扩大和风力发电产业市场化的深入,在风电设备制造、风电场运行管理、电能质量控制、风电环保问题以及风电与其它形式能源的联合使用等方面还存在一系列技术问题。要使风力发电成为人类发展的一种主要能源,有赖于这些问题的解决。我国风力发电研究已…     

关于我国可再生能源发电产业的探讨

我国可再生能源发电产业现状及背景我国目前已拥有 3亿千瓦的电力装机 ,国电公司全额投资、控股或掺股的电厂占总装机的一半左右。全国发电量达到 1.2万亿千瓦时。其中火力发电量占总发电量的 74 .5 % ,可再生能源发电不足 1‰ (未包括小水电 )。风力发电总装机容量 34万千瓦 ,风机国产化率可达 4 0 %以上 ;太阳能光伏发电总装机容量 2万千瓦 ,9个国内生产厂家的年生产能力达 1万千瓦以上。我国电力行业发展的传统模式是“大机组、大电网、高电压、集中供电”。今后很长一段时间内 ,我国电力行业还将继续沿着这样的模式发展。但是这种模式是…     

机车电传动系统实验平台

介绍了一种新开发的机车电传动系统实验平台,给出了该系统组成、控制策略以及相关的技术特点和性能描述。这种实验平台最大限度地在硬件上模拟了机车的交流传动和直流传动系统,可以帮助相关专业领域的学生和工作人员理解机车电传动系统的工作原理,也可以在这套平台上进行相关的二次开发和研究工作。     

Equity and electric power generation facility location in California

An alternative to cost/benefit analysis for analyzing the equity of electric power generation facility location, utilizing the potential for air quality degradation, is developed and applied to California. Siting issues motivating disagreement on facility location are reviewed. Equity concepts are introduced, and their implementation is discussed. Several measures for assessing the equity of facility location are proposed, and the equities of existing facility locations in California are analyzed for each measure. Equity considerations for future siting decisions are examined.     

Analysis method for non-schedulable generation in electric systems

The usefulness of alternative electric energy sources cannot be assessed without considering their operation within the context of the connected electric system. The value of wind and solar power is strongly dependent on the relationship of the times at which power is available to the times of peak load. A load-duration methodology is developed to assess the economic impact of alternative energy sources on the operation and expansion of the entire system. This methodology treats unschedulable generation as a negative load and obtains a modified load duration curve. On the other hand, schedulable or interruptible load can be treated as negative generation in meeting the load. Where the unit size for dispatching is a small fraction of the system, a continuous-function representation is used. Random factors in availability and load are treated statistically. Economic impacts are evaluated as perturbations on present operations.

Differences are found between intermittent energy sources which are correlated with the load, and sources which are random; and between short-term and long-term impacts.

The results indicate that the benefits per unit of the individual alternative-energy devices are greatest for small penetrations. However, at larger penetrations some additional benefits may be derived from the interaction of complementary technologies.

The load-duration methodology is shown to identify the same trends as hour-by-hour dispatch simulation. It is useful for screening potential applications of new technologies to utility systems, or to estimate future cost-of-service rates to co-generators and small power producers.     

Unified model of solar thermal electric generation systems

In this paper a unified model of a solar electric generation system (SEGS) is developed using a thermo-hydrodynamic model of a trough collector combined with a model of a traditional steam power-house. The model evaluates thermal properties, steam flow rate and pressure drop in a direct steam generation (DSG) or an oil based collector field. The SEGS’s performance in different collector field power-house arrangements is evaluated. Long term performance is implemented by integrating the unified model in TRNSYS using hourly radiation data from the currently operating SEGS site in California. The performance of SEGS under Jordanian radiation conditions is studied by evaluating the yearly delivered energy from a collector field at different sites.     

High-performance electric machines for renewable energy generation and efficient drives

Advances in permanent magnets, electronics and design techniques over the past thirty years have led to the development of a new generation of electric machines. Sintered rare-earth neodymium–iron–boron magnets have a magnetic energy product up to an order of magnitude larger than those of alnico and ferrite magnets, with high remanence and coercive force. Coupled with new smart power electronics and the use of advanced computer aided design optimisation, the new machines are of high efficiency and/or compact size. Some state of the art developments of high-performance machines are reviewed with particular examples drawn from a number of novel designs developed by UTS and CSIRO.     

Spatial and temporal analysis of electric wind generation intermittency and dynamics

A spatial and temporal analysis of wind power generation characteristics was conducted in order to determine the implications of intermittent wind generation dynamics on the profile of the electric loads that must be balanced by dispatchable electrical generators on the electric grid. A parametric analysis was conducted to evaluate the sensitivity of the typical magnitudes of wind power fluctuations on different timescales, power variation range, typical daily and seasonal wind profiles to wind farm size and regional distribution. A methodology to evaluate wind dynamics based on power spectral density analyses have been developed. Results indicate that increasing the size of a local wind farm significantly reduced the magnitude of wind power fluctuations on timescales faster than 12 h, with the largest reductions occurring at the fastest timescales. Additional reductions in power fluctuations can be achieved with the implementation of local and regional distribution of wind turbines in disperse high wind areas. In these cases, it was discovered that the timescale band within which the largest reductions in power fluctuations occurred was dependent on regional geographic features, and did not necessarily correspond to the fastest timescales. In addition, it was also discovered that the aggregation of wind power from different regions could produce a more uniform frequency distribution of power fluctuation reductions.     

Reliability assessment of generation and transmission systems using fault-tree analysis

This paper presents a method that integrates deterministic approach with fault-tree analysis for reliability assessment of a composite system (generation and transmission in power systems). The contingency screening is conducted in the first step. The results are further classified into three clusters in the second step: normal, local trouble and system trouble. The fault-tree analysis is used to assess the reliability of the composite system in the third step. Finally, Risk Reduction Worth is adopted as a measure of importance for identifying the crucial element that has significant impact on the reliability. In this paper, a composite system in Taiwan serves as an example for illustrating the simulation results attained by the proposed method. The simulation results, verified by Siemens PTI PSS/E TPLAN software package, show that the proposed method is applicable for large scale power systems.     

Global warming and electric power generation: What is theconnection?

The greenhouse effect is explained, followed by a discussion of the US fossil fuel use and its contribution of greenhouse gases. US electric utilities' share of CO₂ and other emissions is quantified, including the effects of using various fuels. The possible recovery and disposal of CO₂ from power-plant flue gases is also discussed. The information presented should help prepare electric utilities to address future public concerns and the related regulatory pressures regarding the utility's role in carbon-dioxide proliferation and global warming     

Private electric power generation as an alternative in Nigeria

About 9% of the energy mix in Nigeria is in the form of electricity. It is a major source of energy for the urban population. In the recent past, there has been consistent failure of electricity supplied by the public organisation. Consumers are now turning to private means to meet their electricity needs. We have assessed the electricity supplies from the national grids and from private electricity generators.     

Concerns generated by islanding [electric power generation]

The purpose of this article is to discuss islanding operation and to provide end-users with items to consider when determining distributed generation plant and equipment design requirements. Islanding is operating an electric generating plant without an external voltage and frequency reference. Operating in parallel is the opposite of islanding. This article attempts to describe the valid concerns that grid operators have regarding distributed generators. Grid computing could offer an inexpensive and efficient means for participant to compete in providing reliable, cheap and sustainable electrical energy supply. With a keen awareness of the issues involved and open communication among the grid operators, generator control system manufacturers, clients and design firms, distributed generators can be operated in islanded mode without negatively impacting the grid and can continue to support facility operations.     

High efficiency electric power generation: The environmental role

Electric power generation system development is reviewed with special attention to plant efficiency. It is generally understood that efficiency improvement that is consistent with high plant reliability and low cost of electricity is economically beneficial, but its effect upon reduction of all plant emissions without installation of additional environmental equipment, is less well appreciated. As CO₂ emission control is gaining increasing acceptance, efficiency improvement, as the only practical tool capable of reducing CO₂ emission from fossil fuel plant in the short term, has become a key concept for the choice of technology for new plant and upgrades of existing plant. Efficiency is also important for longer-term solutions of reducing CO₂ emission by carbon capture and sequestration (CCS); it is essential for the underlying plants to be highly efficient so as to mitigate the energy penalty of CCS technology application. Power generating options, including coal-fired Rankine cycle steam plants with advanced steam parameters, natural gas-fired gas turbine-steam, and coal gasification combined cycle plants are discussed and compared for their efficiency, cost and operational availability. Special attention is paid to the timeline of the various technologies for their development, demonstration and commercial availability for deployment.     

Thermodynamic analysis of combined electric power generation and water desalination plants

The performance of three systems combining reverse osmosis (RO) to produce drinkable water and a steam power plant is modeled and calculated. The RO subsystem incorporates a power recovery unit: a hydraulic turbine in the first two cases and a pressure exchange unit (PES) in the third case. The coupling between the RO and power plant subsystems is only mechanical in the first case (the power plant provides mechanical power to the pumps of the RO subsystem) while in the two other cases the coupling is both mechanical and thermal (part of the heat rejected by the condenser of the power plant is transferred to the seawater). The effects of feed water flow rate and salinity, energy recovery system (hydraulic turbine or pressure exchanger) and operating pressures on the energy and exergy efficiencies and on the permeate quantity and quality are analyzed. Energy and exergy fluxes for all the components, as well as the quantity of drinkable water produced by each of these systems, are also compared for identical operating conditions.     

Economics of electric power generation options and sulfur oxide emission control

By the use of spreadsheet techniques, a simple but versatile program has been developed for analyzing the economics of electric power generation for all types of plants. The incentives for various power-generation options are quantified.The impact of SO_x, emission control using flue-gas desulfurization (FGD) on power cost is about $0.013/kWhr for plants with a load factor of 0.7 and represents 20% of the power cost. It is shown that use of an aged plant is more economical than of a new plant equipped with FGD to meet the SO_x emission regulations, even though continued use of old plants defeats measures for environmental improvement. With the current price structures, continued use of an aged, oil-fired, steam-electric plant is economically attractive, and a natural gas combined-cycle electric plant may now be economically viable.