A comprehensive review on the grid integration of doubly fed induction generator

As a result of the growing demand for electricity and environmental constraints, the generation of electrical energy from renewable sources of energy has increased recently. The renewable energy sources, especially wind power plants are integrated to power networks all around the world. The rising share of wind turbine energy, in the existing power system, has created new opportunities and challenges. For wind turbine energy generation doubly fed induction generators are most suitable due to their various advantages over fixed speed wind turbine systems. These generators have ability to improve stability and power quality of the existing power systems. Therefore more attention has been paid by many researchers recently to address various challenges of grid connection of DFIG. A comprehensive survey, of different issues associated with integration of DFIG based system into the grid is presented in this paper.     

Power Electronic Drives,Controls, and Electric Generators for Large Wind Turbines–An Overview

Abstract—Wind represents a major and growing source of renewable energy for the electric power systems. This article provides an overview of state-of-the-art technologies and anticipated developments in the area of power electronic drives, controls, and electric generators for large multi-megawatt wind turbine systems. The principal components employed in a turbine for energy conversion from wind to electricity are described, and the main solutions that are commercially available are briefly reviewed. The specific issues of complex mission profiles, power codes, and reliability are discussed. Topics of power electronics, ranging from devices to circuit topologies, and similar matters for electric generators, together with results of optimal design studies are included. It is shown that the individual power rating of wind turbines has increased over the years, and technologies required to reach and exceed a power rating of 10 MW are discussed. The role of power electronics for improving the operation of wind turbines and ensuring compliance with power grid codes is analyzed with a view at producing fully controllable generation units suitable for tight integration into the power grid and large-scale deployment in future smart power systems.     

德国新能源发电发展和运行研究

近年来,德国新能源发展迅猛,新能源发电量占比逐年提高。分析德国各类电源装机、发电量和发电小时数变化,揭示德国近十年来的能源转型历程。分析德国及其与周边国家联络线电量和电价的变化情况,研究新能源发展给德国电价带来的影响。通过典型周电力系统运行数据,分析德国电力系统应对新能源功率波动性的措施。德国新能源发展和运行实践表明,新能源优化运行和最大化消纳主要取决于灵活的电力现货市场机制、强有力的电源调节能力和坚强的跨国输电网络,同时,新能源的发展将对全社会电力生产成本和电价产生重大影响。     

China’s electricity transmission and distribution tariff mechanism based on sustainable development

In order to guarantee the rapid sustainable development of the social economy, the power grid will make large investments in the construction of smart grids, the renewable energy network, the construction of long-distance transmission grid channels as well as the technology and service innovation of the power grid. According to the electricity transmission and distribution tariff accounting mechanism of costs and benefits, the power grid investment needs to be recycled by the transmission and distribution tariff. However, at present, the low electricity transmission and distribution tariff in China, which is based on the difference between the electricity sales price and the average purchase price, cannot guarantee the return of investment and the sustainable development of the power grid. Based on the current situation of China’s power grid construction and electricity transmission and distribution tariff, this paper proposes that the new investments in the power grid can be divided into technical innovation investments, environmentally friendly investments, service promotion investments and other kinds of investments, according to their functions. Then, four electricity transmission and distribution tariff and power grid investment linkage models are built and example analysis undertaken, respectively, which are the timely linkage model, static linkage model, ladder linkage model, in which the electricity tariff space changes by a fixed absolute value annually and ladder linkage model in which the electricity tariff space changes by a fixed proportion value annually. The results reveal that the ladder linkage model in which the electricity tariff space changes by a fixed absolute value annually can guarantee relatively smooth changes in the electricity tariff, and is suitable for the actual situation of China’s power market. The transmission and distribution electricity tariff and power grid investment linkage models based on sustainable development built in this paper are beneficial for promoting the reforms of the electricity transmission and distribution tariff in China and guiding the establishment of a scientific electricity tariff mechanism.     

含风电及电动汽车虚拟电厂参与电力市场的优化调度策略

可再生能源发电及电动汽车充电的不确定性给电力系统运营带来新的挑战。针对含有风力发电和电动汽车充放电的虚拟电厂参与到电力市场中包含的不确定性问题,提出了一种混合储能虚拟电厂参与电力市场的优化调度策略。基于轮盘赌机制建立风力发电不确定性模型,将电动汽车的不确定性参数引入该模型,通过分析电力市场需求,制定基于不确定模型的随机优化调度方案。通过算例验证该方案的有效性和适用性,为混合储能虚拟电厂参与电力市场调度提供指导。     

Renewable energy credit driven wind power growth for system reliability

Environmental concerns over electric power generation from conventional sources has led to widespread public support for renewable energy sources. Governments throughout the world have responded by providing various forms of financial incentives to promote power generation from renewable energy sources. The rapid growth of wind power since the last decade has primarily been driven by governmental subsidies. Long-term growth of wind power should, however, be driven by sustainable market mechanisms. A potential solution is to recognize monetary values to the environmental benefits from renewable energy sources, and to specify targets for their growth. The environmental benefits from wind sources can be leveraged to allow market competition of these sources with the less costly conventional generating sources. A probabilistic method to evaluate the impact of renewable energy credit and wind penetration level on the cost and adequacy of power generating systems is presented in this paper. The technique incorporates reliability and economic analyses and is applied to a published test system to illustrate the results and their influence on key system variables. The paper provides useful information to system planners and policy makers on wind energy application in electric power systems.     

考虑可再生能源消纳的火电机组市场力评估

随着可再生能源并网比例的不断提升,实现其全额消纳会对火电机组的市场机会产生越来越大的冲击。针对这一现象,提出了火电机组综合市场力评估方法。考虑可再生能源发电并网下火电机组备用作用的强化,对传统市场力指标——Lerner指数进行修正,建立了反映火电机组在电量市场与备用市场综合市场力的改进Lerner指标;同时计及风电出力的不确定性,采用正态分布与拉普拉斯分布的联合概率密度函数更好地反映风电预测误差的尖峰厚尾特性,完善了备用需求的表达;以电量完全竞争作为假设前提,采用电量—备用联合优化模型模拟电力市场交易,进而完成对火电机组综合市场力的准确度量。以10机系统为例进行仿真计算,验证了改进指标的有效性并分析风电渗透率、风电预测精度等因素变化对火电机组综合市场力的影响。     

可再生能源发电对实时电价的影响分析——德国电力现货市场的数据实证

电力现货市场实时交易可充分发挥市场调节作用,促进可再生能源消纳。基于数据实证分析可再生能源发电对实时电价的影响,对理解现货市场运行规律、开展市场成熟度评价等具有重要参考价值。选取德国电力现货市场开展数据实证,收集发电量、负荷量、预测误差、价格等多因素数据,基于时间序列特征表示方法,研究可再生能源发电对实时电价的影响。首先,使用特征表示方法将时间序列时域模型转化为特征向量。然后,采用贪婪向前特征选择算法提取关键特征,最大化因素间差异。接着,分别基于全部特征和关键特征讨论了多因素间的相关性,并构建了影响机理网络图。实证结果表明德国电力现货市场实时电价主要受到风力发电量预测误差影响,因素间相关性主要来自时间序列的傅里叶变换、小波变换、离散符号化等特征。最后,通过中德电力现货市场的定量对比,指出中国广东电力市场实时电价更易受新能源发电量而非预测误差的影响。     

基于风光荷储联合优化的虚拟电厂竞价策略

基于电力市场的竞价机制和虚拟电厂的运行机制,构建了以风电-光伏-负荷-储能联合运行体利润最大化为目标的优化决策模型。该模型充分考虑新能源机组,储能与负荷运行时的各项技术约束条件,通过虚拟电厂中风-光-荷-储间协调耦合运行的发电策略与出力安排等,实现新能源与电动汽车联合参与市场竞价。构建算例验证了该风光储联合运行优化决策模型的正确性与有效性,并通过对多组场景对比,分析新能源出力波动性对风-光-荷-储联合运行模式的竞价策略的影响。     

新型电力系统背景下可再生能源参与电力市场交易策略研究

随着可再生能源接入比例和规模的扩大,可再生能源参与电力市场交易,多维度协同消纳正逐渐成为可再生能源并网发展趋势。从源荷两侧选取可再生能源场站、传统发电企业、电网企业等典型电力市场交易参与方,建立多方交易策略模型。利用合作型协同进化遗传算法求解纳什均衡,对各参与方的成本收益进行效益分析,为典型电力市场交易场景的多方交易策略模型的建立提供基础。通过算例计算分析表明,风电商与电动汽车用户联合组成虚拟电厂,参与电力市场交易所获得的利润比其单独参与电力市场的利润高出27.5%,说明虚拟电厂在充分利用风电资源的同时,还能调用电动汽车电源存储能力,创造更大的经济价值,具有更强的市场竞争力。     

计及日前-实时交易和共享储能的VPP运行优化及双层效益分配

随着“双碳目标”的提出和可再生能源渗透率的增加,确保电力系统灵活运行变得愈加重要。针对源、荷、储等多类分布式灵活性资源,构建了电力市场环境下计及风光不确定性和共享储能的虚拟电厂(virtual power plant,VPP)运行优化和双层效益分配模型。首先,构建了含分布式风光机组、共享储能、柔性负荷的VPP系统结构,并建立了两级电力市场交易机制。其次,利用场景生成与削减的方法处理了风光出力不确定性,在此基础上以VPP运行收益最大化为目标,构建了考虑日前-实时交易的VPP运行优化模型。再次,为保障参与主体收入公平性和合理性,基于双层合作博弈Owen值法,分别建立了VPP参与主体收益分配策略和共享储能投资主体收益分配策略。最后,通过算例分析验证了所提模型的有效性。算例结果表明含共享储能的VPP能够有效降低风光不确定性造成的干扰,提高VPP在日前-实时两级市场中的收益;通过Owen值法对各投资主体进行效益分配,有助于保障系统的公平合理性。     

计及日前-实时交易和共享储能的VPP运行优化及双层效益分配

随着“双碳目标”的提出和可再生能源渗透率的增加,确保电力系统灵活运行变得愈加重要。针对源、荷、储等多类分布式灵活性资源,构建了电力市场环境下计及风光不确定性和共享储能的虚拟电厂(virtual power plant,VPP)运行优化和双层效益分配模型。首先,构建了含分布式风光机组、共享储能、柔性负荷的VPP系统结构,并建立了两级电力市场交易机制。其次,利用场景生成与削减的方法处理了风光出力不确定性,在此基础上以VPP运行收益最大化为目标,构建了考虑日前-实时交易的VPP运行优化模型。再次,为保障参与主体收入公平性和合理性,基于双层合作博弈Owen值法,分别建立了VPP参与主体收益分配策略和共享储能投资主体收益分配策略。最后,通过算例分析验证了所提模型的有效性。算例结果表明含共享储能的VPP能够有效降低风光不确定性造成的干扰,提高VPP在日前-实时两级市场中的收益;通过Owen值法对各投资主体进行效益分配,有助于保障系统的公平合理性。     

Review of Marine Hydrokinetic Power Generation and Power Plant

Abstract

Marine hydrokinetic power generation is a relatively new type of renewable generation. Its predecessors, such as wind power generation, hydropower plant generation, geothermal generation, photovoltaic generation, and solar thermal generation, have gained a lot of attention because of their successful implementation. The successful integration of renewable generation into the electric power grid has energized the power system global communities to take the lessons learned, innovations, and market structure to focus on the large potential of marine hydrokinetic to also contribute to the pool of renewable energy generation. This article covers the broad spectrum of marine hydrokinetic generation. The state of the art of power take-off will be discussed. Types of electrical generators will be presented, and the options for implementation will also be presented.     

碳市场与电能量市场均衡交易分析

为了减少温室气体的排放,有必要开展碳排放总量控制与交易机制设计工作。总结了电力工业中碳市场交易发生的条件,并基于碳排放效用曲线分析了碳市场交易对发电商剩余的影响。建立了碳市场和电能量市场均衡交易模型,量化分析碳市场与电能量市场的出清情况。该均衡交易模型考虑了碳排放权约束,可以使清洁能源机组获得更多的发电量,有利于低碳电力技术的发展。     

Optimization of Lebanon's power generation scenarios to meet the electricity demand by 2030

Presently, Lebanon provides 95 % of the primary energy electricity power generation by using fuel-oil used in thermal power plants. To meet the population needs, private generators are also used in all the country and they represent the third of total electricity production. The challenges over the future development of the Lebanese electric sector are economic and environmental. This is why currently, the energy policy makers aim to diversify the national electricity generation mix in the energy planning strategy and to introduce low-carbon technologies. The complexity of these challenges in the particular Lebanese context has motivated our study which aims to recommend policies to develop the optimal electricity generation scenario by 2030. This paper presents a methodology to evaluate different scenarios reflecting different combinations of technologies by 2030. This is achieved by using an excel tool “Excel Solver Optimization Calculator” which makes possible the interaction of various inputs to produce a least-cost generation mix. The main results focus on the least-cost electricity generation portfolio, total investment required to generate electricity, level of energy independence and carbon emissions. Many policy choices could be feasible and very advantageous for Lebanon if renewable energies are deployed massively. However, this requires policies that support the massive use of renewable energy technologies in the mix.     

Potential impacts of emission concerned policies on power system operation with renewable energy sources

Electricity sector is considered as major source of green house gas emission. A huge opportunity exists within this sector to cut down the emission and contribute significantly to mitigate the climate change. The Emission Trading Schemes (ETSs) and inception of renewable energy sources (RESs) into the generation mix contribute to the reduction of emission and impact electricity market operation. This paper investigates the impact of emission concerned policies, such as: (a) fixed emission quota; (b) cap and trade; and (c) bilateral contract commitments; on the operation of power system. The renewable support mechanisms, such as renewable purchase obligation (RPO) and feed-in-tariff are incorporated so as to account the relative costs of cleaner and renewable generation technologies. Each generator is allocated certain amount of emission allowances, which they can use to cover emission during energy generation. The electricity and emission prices are obtained from the interaction of carbon and energy market. It is observed that, the renewable support mechanisms affect the generating and emission trading schedule of independent power producers (IPPs). They help them meet their emission targets and increase overall welfare. A balance between the emission regulation and renewable support mechanisms is essential, otherwise they make each others effect redundant. The performance of the proposed model is demonstrated by its implementation on a five generators system.     

考虑风光不确定性与电动汽车的综合能源系统低碳经济调度

综合能源系统耦合负荷侧多种能源需求,是就地消纳分布式能源的有效手段。为协调多利益相关者场景下综合能源系统与电动汽车之间的调度问题,提出了一种考虑风光不确定性与电动汽车的综合能源系统双层模型的优化调度策略。首先,针对风光出力随机性,采用拉丁超立方采样生成场景,然后利用改进削减速率的快速前代消除技术进行场景削减。其次,为了挖掘电动汽车的需求响应潜力,在分时电价基础上,根据负荷与可再生能源的匹配度提出一种动态定价机制来引导电动汽车有序充放电,并研究其充放电策略对运行成本与碳排放量的影响。最后,算例分析结果表明,与分时电价相比,所提定价机制与调度策略能提高能源利用率与EV的调度灵活性,有效降低两利益相关者的运行成本与系统的碳排放量。     

计及光伏不同交易模式的售电公司日前市场购售电策略

随着我国电力体制改革的深化以及可再生能源的发展,让可再生能源参与电力市场将成为促进其消纳的重要手段之一。在光伏发电商与售电公司开展的2种市场交易模式的基础上,考虑了日前市场出清电价、光伏出力的不确定性,通过场景法与信息间隙理论相结合,构建了售电公司日前市场购售电模型,以利润最大化为目标,对模型进行求解。最后通过算例分析,验证了所建模型的有效性,为售电公司参与市场竞争提供了有效的参考。     

充电设施用电需求参与大用户直接交易模式

电动汽车充电业务在飞速发展的同时,也面临着盈利模式单一、投资回收慢等问题,不利于行业的持续发展。从降低运营成本的角度出发,探讨了充电设施用电需求参与大用户直接交易以及消纳风电、光伏等新能源富余电力的可行性,提出了将充电设施用电需求打捆、参与大用户直接交易的路径与模式,并在此基础上对参与交易后的盈利空间进行了简单估算。该模式的应用,将显著降低电动汽车用电成本,有效促进新能源消纳利用,实现新能源产业与电动汽车产业的协同发展。     

促进新能源消纳的电力交易偏差结算补偿机制

随着新能源参与市场交易的比例不断扩大,由于其波动性强、预测准确度低等特性,引起新能源电厂基数电量分配不均、合同电量滚动到年底仍无法结算等问题,使得设计新能源电厂参与电力市场交易偏差结算机制尤为关键。文中立足新能源参与电力交易现状,提出新能源替代利益补偿办法。首先,基于结算日新能源电厂实际发电量减去事前合同电量,按机组装机容量确定基数电量。然后,针对市场中各电厂参与交易的电量和电价,确定新能源电厂结算综合单价,核定超发电厂对少发电厂的经济补偿。最后,通过具体算例得出该方法可以使得市场份额高的电厂获得高利润,同时,按月结算电费保证了交易合同的执行力。