Hybrid wind power balance control strategy using thermal power,hydro power and flow batteries

The increased number of renewable power plants pose threat to power system balance. Their intermittent nature makes it very difficult to predict power output, thus either additional reserve power plants or new storage and control technologies are required. Traditional spinning reserve cannot fully compensate sudden changes in renewable energy power generation. Using new storage technologies such as flow batteries, it is feasible to balance the variations in power and voltage within very short period of time. This paper summarises the controlled use of hybrid flow battery, thermal and hydro power plant system, to support wind power plants to reach near perfect balance, i.e. make the total power output as close as possible to the predicted value. It also investigates the possibility of such technology to take part in the balance of the Lithuanian power system. A dynamic model of flow battery is demonstrated where it evaluates the main parameters such as power, energy, reaction time and efficiency. The required battery size is tested based on range of thermal and hydro power plant reaction times. This work suggests that power and energy of a reasonable size flow battery is sufficient to correct the load and wind power imbalance.     

Reliability of a small power system using solar power and hydro

This paper studies the availability of the electricity supply when the sources consist of a combination of solar energy and a small hydro installation. Instead of flow-of-river, a small reservoir is used. By not using the hydro energy during sunny periods, the natural flow-of-river fills up the reservoir for later use. A model for global solar radiation is proposed with an astronomical part (deterministic) and a meteorological part (stochastic). The meteorological part is based on a Markov model of the cloud coverage. The solar model does not require solar radiation measurements, just cloud observations. A case study has been performed for Timbuktu (16.75°N, 0.07°W) in which generation availability is simulated for four different cases: solar power only; solar power with storage; solar and hydro power and solar and hydro power with storage. To be able to use exclusively renewable energy sources, a combination of sources is needed to secure the reliability of the supply. Using solar cells in combination with a small reservoir is favorable. Even with a weak flow the affect of the flow on the day time reliability is minor, but great benefits can be found for reliability during low load hours (night time).     

促进可再生能源消纳的多能互补时序运行模拟技术

针对风、光、水多种可再生能源多能互补效益的准确评估问题，基于多风电场与太阳能光伏电站的中长期随机出力时序模拟，考虑库容影响的水电短期优化方法，以中长期水电优化结果为边界，提出水/火/风/光多种能源协调互补的电力系统时序运行模拟模型，并以可再生能源装机比例较高且消纳问题严重的中国西部电网为实证案例进行生产运行模拟计算。研究结果表明：西北、西南地区电源结构、负荷特性差异较大，跨区互补优势明显；建设西北与西南联网通道，可以实现多能互补，有效提高可再生能源外送通道利用效率，提升西部地区可再生能源消纳能力。     

基于风蓄协调的节能调度方法

为解决节能调度中风能接入造成运行成本增加和可靠性降低的问题,提出了一种基于风蓄协调系统的节能调度方法。通过引入多个整型优化变量与协调周期不平衡量约束,反映抽水蓄能机组发电、抽水、空闲等不同运行状态以及风电机组的出力波动特性,并采用混合整数规划方法求解。算例分析表明,该模型能克服风能的间歇性和波动性缺点,提高系统运行可靠性与风能利用率,降低整体运行成本,能提供抽水蓄能机组适应节能调度需求的新型调度方案,具有显著的经济效益与实用价值。     

可再生能源高渗透率区域“网-源-储-荷”协调规划案例分析

为应对可再生能源快速发展,适应能源互联网的发展需求,以规划大规模接入可再生能源的金寨县为例,进行了“网-源-储-荷”协调规划研究。通过配置储能、水电调节以及主动负荷控制等,充分利用原有电网资源,实现可再生能源的就近接入与就地消纳;通过地区风光互补,并与大型火电及抽水蓄能电站进行协调运行优化,显著降低了各层级电力外送规模。     

考虑断面约束的多能源电力系统时序性生产模拟

传统电力系统随机生产模拟方法难以描述新能源发电机组时序特性以及计算与时序特性有关的电力系统运行指标,导致生产模拟的准确性欠佳.提出含风电、光伏、水电、火电、光热及储能的多能源时序性随机生产模拟方法.将系统运行调度策略与随机生产模拟中各类型机组的加载顺序相结合,计及电力系统网架断面约束,充分保证新能源的优先消纳.为保留电力系统时序特性,基于等效电量函数法以每小时作为模拟步长统计模拟期间内的系统运行指标.我国某省实际电力系统随机生产模拟结果验证了所提方法的有效性.     

风水储微电网优化调度策略研究

为了缓解风电因随机波动性对电网造成的冲击,增强风电的可控性,提出一种基于分频段补偿法的风水储微电网优化调度策略。该策略根据水电机组输出带宽,通过小波分解法对风电功率信号进行多尺度分解,得到水电机组和储能系统初级功率指令,再根据水机爬坡能力,对初级功率指令进行修正得到最终功率指令。基于MATLAB/Simulink平台建立了风水储微电网仿真模型,分析了所提调度策略与现有策略的控制效果,结果表明,所提调度策略能减小储能所需容量,降低储能配置成本;改善了微网内水机过渡过程,有利于微网稳定运行;提高了风电的可控性,使微网有功输出更平滑。     

Optimum scheduling of micro grid connected wind-pumped storage hydro plant in a frequency based pricing environment

This paper presents a new formulation to maximize the operational profit of a micro grid connected hybrid system having wind farm and pumped storage unit for a day ahead electricity market in a frequency based pricing environment. Under frequency based pricing mechanism in India, the pricing for energy exchange is adaptive as per Availability Based Tariff (ABT) rate structure and the payment for deviation from schedule, i.e. Unscheduled Interchange (UI) charge is inversely proportional to the prevailing grid frequency. In this work, a small power system is considered as micro grid and it is expected that the hybrid system connected with the micro grid has a role to play to maintain the micro grid frequency. The pump storage hydro plant is operated to serve the dual role of minimizing the UI flow and maximizing the system economy by participating in frequency control based on energy price. The uncertainties in wind power prediction and loads are considered. The optimum operating schedule of PSH unit in coordination with wind farm is investigated. The optimization is performed by utilizing the water storage availability of pump storage hydro unit. An optimization algorithm is proposed and solved using Artificial Bee Colony algorithm. The solution of the proposed approach gives the strategies to be followed by the hybrid system to operate its pump storage unit. The effect of the initial storage water volume on the performance of the hybrid system has also been investigated. It reveals that the PSH units would not operate simply to compensate for the short fall or the surplus generation of the wind units in a frequency based pricing system. Rather, the pump storage units should take the advantage of the low price periods to maximize the profit of the hybrid system. The hourly energy management scenarios of the hybrid system with the micro grid are reported and the numerical case studies on PSH plant scheduling demonstrate the effectiveness of the proposed approach.     

风储联合系统调频控制策略研究

风力发电作为一种可再生能源发电在电网中的渗透率逐年升高,其具有的随机性、波动性和间歇性给电力系统的安全稳定运行带来了不利影响。与此同时,储能技术在近年来得到大力发展,其快速性和大范围吞吐性可以弥补风电机组单独运行时所带来的不利影响。首先对风电和储能系统的输出特性进行分析。其次针对风电并网发电在遇到频率波动时不具备惯性的问题,提出了应用储能补偿系统惯量,利用频率变化率作为反馈输入并调节惯量常数K,使风储联合系统作为一个整体对外提供有功功率参与电网调频,再利用Matlab/Simulink仿真验证了本文所提出控制策略补偿系统惯量的有效性。最后仿真对比风电机组单独参与电网调频与风储联合系统调频控制策略,得出风储联合系统参与电网调频的优越性。     

Expansion Planning for Renewable Integration in Power System of Regions with Very High Solar Irradiation

In this paper, we address the long-term generation and transmission expansion planning for power systems of regions with very high solar irradiation. We target the power systems that currently rely mainly on thermal generators and that aim to adopt high shares of renewable sources. We propose a stochastic programming model with expansion alternatives including transmission lines, solar power plants (photovoltaic and concentrated solar), wind farms, energy storage, and flexible combined cycle gas turbines. The model represents the long-term uncertainty to characterize the demand growth, and the short-term uncertainty to characterize daily solar, wind, and demand patterns. We use the Saudi Arabian power system to illustrate the functioning of the proposed model for several cases with different renewable integration targets. The results show that a strong dependence on solar power for high shares of renewable sources requires high generation capacity and storage to meet the night demand.     

风电参与电力系统调频控制策略综述

随着可再生能源的大规模开发,以风能为代表的可再生能源大量并入电网,且渗透率不断提高.一方面,由于惯性时间常数较小的风电机组替代了传统发电机组,系统的总体惯量减少;另一方面,由于风能本身所具有的间歇性、随机性,系统的频率特性发生改变,调频能力随之减弱.风电参与调频是解决风电上网约束的有效手段之一.为此,对风电参与调频领域的研究进行综述,首先以双馈风电机组和永磁直驱风电机组这2类最常用的变速风电机组调频控制策略为例,综述风电机组转子超速控制、桨距角控制、虚拟惯量综合控制、虚拟同步发电机控制,储能与风电调频以及多控制策略联合的原理、优缺点和发展趋势等;然后针对风电场参与系统调频的若干问题进行分析;最后对本领域未来可研究的问题进行展望.     

含流域梯级水电的水火风互补发电系统联合运行优化

大规模水电和风电并网后,来水和风速的随机性降低了发电的可控性,如何科学地在多元电源系统联合运行中确定旋转备用容量,更好地协调系统经济性与可靠性,是市场化背景下亟需解决的理论和现实问题。在分析水电和风电的自然与技术互补特性的基础上,建立考虑水流滞时效应的梯级水电水量平衡关系。通过结合传统梯级水电联合调度模型与火电、风电的经济调度模型,引入水力发电的水资源费用成本,综合考虑梯级水电能量转换、水量耦合、库容限制、水流滞时和风电穿透率等多类复杂约束,在分析电能市场与备用市场顺序决策经济意义的基础上,构建以运行成本最小为目标的考虑梯级水电的水火风互补发电系统短期优化运行模型。采用外点罚函数法将模型转化为无约束优化问题,基于加惯性权重的粒子群优化算法,运用MATLAB软件编程实现优化功能。4个梯级水电、3个常规火电、2个大型风电场构成的算例系统验证了所提模型的有效性和适用性。     

离网运行的风能海水淡化系统负荷控制策略

在由风力发电机和储能装置作为海水淡化装置供电电源的离网型配电系统中,为最大化利用风能并减少配电系统对储能装置容量的依赖,海水淡化装置负荷采用功率阶梯调节和功率平滑调节相结合的方式,储能装置采用V/f控制。功率阶梯调节通过海水淡化装置的模块化投切实现;功率平滑调节通过变频器实现电动机的变频调速,并且利用变频器的软启动功能和无功输出能力有效维持配电系统的电压稳定。基于上述控制策略,通过PSCAD仿真软件建立动态负荷模型进行仿真计算并结合负荷实验数据进行分析。仿真和实验结果均表明,该控制策略可以实现海水淡化负荷对风力发电输出功率的有效跟踪,能够很好地适应风电波动性,并充分利用了风力发电机的输出功率,减少了对储能装置容量的依赖,提高了全系统运行的稳定性和经济性。     

基于中长期风电光伏预测的多能源电力系统合约电量分解模型

针对大量新能源参与的电力系统中长期运行,提出考虑电量分解与检修计划相互影响的含风光水能源的电力系统合约电量分解模型。以新能源消纳和检修经济性为目标,旨在合理分解电量的同时提高新能源在资源丰富时段的消纳率,并根据资源分布和各时段能源参与情况安排各类机组检修计划,从而保证机组检修的经济性。由于风光资源的不确定性,从数据挖掘角度出发,提出基于聚类方法的光伏电量预测方法和非参数核密度估计的风电电量预测方法,并以此作为含风光水能源电力系统合约电量分解的基础。最后,通过算例验证了所提模型在含风光水多种能源的电力系统电量分解及机组检修联合优化中的有效性。     

用可再生能源充电的SMES装置在系统调频中的应用

受自然条件限制,可再生能源发电具有很大的随机性,直接并入电网会对系统造成一定的冲击,增加系统不稳定的因素。文中以风能为例,提出将风能等可再生能源作为超导磁储能（SMES）装置的充电电源,为可再生能源的使用提出一个新的思路。SMES装置具有转换效率高且动作快速的特点,能够与系统独立进行有功、无功的交换。因此,SMES装置可以根据系统负荷变化快速调整出力来稳定系统频率及减少不必要的联络线功率流动。仿真结果证明,SMES装置的投入可以有效改善系统频率,解决旋转备用不足的问题。     

基于可靠性和发电性能的新能源发电设备状态评估方法

与传统火电机组不同,新能源发电设备单机容量小,单机停运不会对新能源电站的供电可靠性产生明显影响,因此对新能源发电设备关注可靠性的同时,更应该关注设备的发电性能。为此提出了一种基于可靠性和发电性能双重指标维度的新能源发电设备状态评估方法,提出了发电性能关键指标的计算方法和数据源标准化要求。将该方法在国家风光储输示范工程进行评价应用,通过评估结果数据分析,总结出了新能源发电设备发电性能指标的推荐阈值。所提出的方法能够为新能源发电设备状态评估提供一种新的技术手段。     

A novel method for fault diagnosis of hydro generator based on NOFRFs

Fault diagnosis and recognition of hydro generator are important issues which encounter in repair and security posture assessment. It influences the operational planning and security directly. Volterra series as an effective modeling method has been widely used in modeling and fault diagnosis of hydro generator, but the larger number of kernels limits its application in faults diagnosis. Non-linear output frequency response functions (NOFRFs) as a transformation style of Volterra series have a more intuitive visual and simple structure. In this paper, NOFRFs have been proposed to be employed in fault diagnosis of hydro generator, and a novel online identification method is proposed at the same time. Firstly, NOFRFs models of hydro generators are built. Secondly, a new method for online identification is proposed according to the operational characteristics of hydro generators. Finally, simulation verification has been done to demonstrate the advantage of the proposed method, and experimental studies are put forward on a hydro generator to analyze the failure mechanism in different states. The results indicate that the proposed method is useful and concise for fault diagnosis and nonlinear analysis of hydro generators.     

用于主网削峰填谷调度的风/光/储微电网控制策略

研究风/光/储微电网的调度控制策略,在实现上级电网“削峰填谷”目标的同时使可再生能源利用最大化。按微电网离/并网运行模式、其主网所处的峰/平/谷运行时段以及发/用电供需平衡状况,对风/光/储微电网进行状态空间划分,并分析各状态相互转移条件;在此基础上,研究各状态下的调度控制策略,给出储能单元充/放电功率的最终控制方案。以广西某岛风/光/储微电网示范工程为例,通过代表日运行控制的仿真实验,验证所提出的削峰填谷调度控制策略的正确性和有效性。     

不同风速概率分布参数下的风力抽水储能分析

介绍建立的风力抽水储能模型,推导了风能转换为电能后抽取的水质量关系式.在此基础上综合考虑风电场风速的随机特性,提出用Monte Carlo仿真产生每小时的风速抽样来计算风能特征指标.最后通过算例分析利用该方法计算了风速概率分布参数对抽水量的影响.结果表明,风力抽水储能是可行的.     

风光储微电网并网联络线功率控制策略

主动配电网环境下,将发电具有间歇性和随机性特点的小风电、光伏发电与蓄电池组成微电网,协调控制其内的多个可再生发电单元使其成为发电功率分时恒定的发电单元或者负荷,既方便配电网对微电网群的调度和管理,又能促进分布式可再生能源的安全消纳。在综合考虑风光储微电网风速曲线和光照条件瞬时变化且储能容量配置较小等实际情况下,提出一种分层协调控制策略。首先根据每时段风速及光照强度预测信息给出了联络线分时交换功率的计算方法,上层中心控制器将该联络线交换功率参考值与上级主动配电网调度中心通信,制定分时联络线交换功率。上层中心控制器并依据此分时功率需求实现系统运行模式的选择及切换以及底层控制器的选择和管理。该分层控制策略实现了运行状态的无缝转换,保证了风光储微电网按照联络线交换功率需求输出,即联络线功率分时恒定。当微电网内风电和光伏输出的瞬时功率之和与联络线交换功率需求相差较大时,微电网内可能会出现部分弃风弃光。该文建立了风光储微电网仿真系统,仿真结果验证了所提策略的正确性与有效性。