Difference between grid connections of large-scale wind power and conventional synchronous generation

In China, regions with abundant wind energy resources are generally located at the end of power grids. The power grid architecture in these regions is typically not sufficiently strong, and the energy structure is relatively simple. Thus, connecting large-capacity wind power units complicates the peak load regulation and stable operation of the power grids in these regions. Most wind turbines use power electronic converter technology, which affects the safety and stability of the power grid differently compared with conventional synchronous generators. Furthermore, fluctuations in wind power cause fluctuations in the output of wind farms, making it difficult to create and implement suitable power generation plans for wind farms. The generation technology and grid connection scheme for wind power and conventional thermal power generation differ considerably. Moreover, the active and reactive power control abilities of wind turbines are weaker than those of thermal power units, necessitating additional equipment to control wind turbines. Hence, to address the aforementioned issues with large-scale wind power generation, this study analyzes the differences between the grid connection and collection strategies for wind power bases and thermal power plants. Based on this analysis, the differences in the power control modes of wind power and thermal power are further investigated. Finally, the stability of different control modes is analyzed through simulation. The findings can be beneficial for the planning and development of large-scale wind power generation farms.

Industrial Arrangement of Large-scale,Non-grid-connected Wind Power Industrial Zones in Coastal Areas of China

Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge but an industrial problem as well.The objective of this study is to introduce a concept of large-scale,non-grid-connected wind power(LSNGCWP) industrial zones and establish an evaluation model to assess their industrial arrangement.The data of wind energy,industry,nature resources and socio-economy were collected in this study.Using spatial overlay analysis of geographic information system,this study proposes a spatial arrangement of the LSNGCWP indus-trial zones in the coastal areas of China,which could be summarized as the 'one line and three circles' structure,which will contribute to the optimization of the industrial structure,advance the wind power technology,coordinate the multi-industrial cooperation,and upgrade the industrial transformation of China's coastal areas.

Design of Large-Scale Prestressing Bucket Foundation for Offshore Wind Turbines

The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads. The finite element model of a large-scale prestressing bucket founda- tion for offshore wind turbines is set up and the structural characteristics of the arc transition structure of the founda- tion are analyzed for 40-60 channels(20-30 rows) arranged with prestressing steel strand under the same ultimate load and boundary conditions. The mechanical characteristics of the key parts of the foundation structures are illus- trated by the peak of the principal tensile stress, the peak of the principal compressive stress and the distribution areas where the principal tensile stress is larger than 2.00 MPa. It can be concluded that the maximum principal tensile stress of the arc transition decreases with the increasing number of channels, and the amplitude does not change signifi- cantly; the maximum principal compressive stress increases with the increasing number of channels and the amplitude changes significantly; however, for the distribution areas where the principal tensile stress is larger than 2.00 MPa, with different channel numbers, the phenomenon is not obvious. Furthermore, the principal tensile stress at the top of the foundation beams fluctuantly increases with the increasing number of channels and for the top cover of the bucket, the principal tensile stress decreases with the increasing number of channels.

Providing Frequency Support of Hydro-Pumped Storage to Taiwan Power System with Wind Power Integration

The combination of wind and pumped storage is a useful method to compensate the fluctuation of wind power generation, which would exploit the abundant wind potential and increase wind power penetration. Taiwan Power Company (TPC) develops renewable energy actively in recent years. Moreover, TPC has started planning a high penetration wind power system and building offshore wind farms around the coast of Zhangbin, Yunlin and Penghu. The target of the offshore wind power installed capacity is up to 3 GW by 2025. However, the integration of the large scale of wind power would give huge challenges to the system operator because wind is randomly characterized. In this study, after high penetration wind power is integrated, the impacts of system frequency and the dispatch of conventional units will be discussed. Additionally, the hybrid system combing wind power with pumped-storage will be planning to reduce the effect of system frequency.

考虑海缆实际载流量的海上风电集电系统拓扑优化

海缆实际载流量是海缆选型的重要依据,在海上风电场集电系统拓扑优化中,考虑不同敷设区段海缆载流量存在的差异以及海缆多回路并联敷设时磁热效应对载流量的影响,对保障集电系统的安全性具有重要意义。首先,采用模糊C均值算法对风机进行聚类分区,将集电系统拓扑优化分解为分区内、外拓扑优化。然后,在分区内采用基于Voronoi图的拓扑搜索算法进行求解;在分区外拓扑优化中,考虑海缆瓶颈区段、回路数对载流量的影响,构建混合整数非线性优化模型,线性化后采用优化求解器GUROBI进行求解。最后,以某实际风电场为例进行仿真验证。结果表明,所提模型能保证海缆实际载流量始终大于海缆工作电流,可有效保障集电系统的安全性。

基于二极管分散整流的风电机组中压直流汇集直接送出系统

基于二极管分散整流的风电机组中压直流汇集直接送出系统可以省去海上升压站及海上换流站,对于中远距离、中等规模海上风电具有突出经济优势。针对其特有的输电电流纹波问题,建立了多机动态移相参考坐标系(DPSRF)并提出按DPSRF坐标系d轴定向的电压矢量控制,实现多台机组的分散式二极管整流器整流电流矢量和输出电流纹波的交错分布,有效降低直流输电电流和电压纹波。计及纹波交错算法中动态移相角影响,建立风电机组网侧变换器小信号状态空间模型,基于特征根分析辨识系统弱阻尼环节,并针对性地提出镇定控制策略。发挥该系统有望免除直流断路器的优势,制定了基于扰动注入的故障定位策略,配合继电保护逻辑和机组动作时序实现无通信依赖的直流内网多故障位置故障定位与隔离。最后,PSCAD仿真和基于RT-LAB的硬件在环实验验证了所提控制保护策略的有效性。

新能源风力发电项目66 kV系统应用前景研究

随着“3060”碳达峰、碳中和目标的实施,大容量风电基地将不断出现,未来风电机组单机容量越来越大,集电线路采用66 kV电压等级,由于其在投资和电能损耗方面的优势,将是风电场发展的必然趋势。文章对35 kV与66 kV集电线路的经济性进行分析,以期为相关人员提供参考。

海上风电全直流汇集送出系统自适应振荡抑制策略

海上风电全直流汇集送出系统中各DC/DC变换器以串并联形式组网,其控制之间相互耦合,极易诱发直流母线电压振荡。为抑制海上风电全直流汇集送出系统的直流母线电压振荡,提出一种基于直流镇定器的自适应振荡抑制策略。建立系统中各DC/DC变换器的阻抗模型。在风机机端升压端口处并联直流镇定器,通过提取直流电压的振荡频率,自适应地控制输出电流跟踪其参考值,实现输出电流与直流母线的振荡电压分量同频同相,重塑了风机机端升压端口对应谐振频率附近的阻抗。基于所提方法的振荡抑制机理,设计了期望输出导纳系数的取值界限并进行了直流镇定器的容量配置。通过阻抗稳定性分析和PLECS仿真,验证了所提方法抑制系统直流母线电压振荡的有效性。

山区风电场道路及集电线路协同优化设计

以某山区风电场为研究对象,基于最短路径Dijkstra算法,以风电场场内新建道路路径和电缆长度最短为优化目标,建立了满足山区风电场的道路纵坡坡度、最小转弯半径、敏感区、边界、桩距等约束条件的选线算法,该算法的特点一是采用规则三角网格和对角距启发式函数来搜寻六个方向,满足最小转弯半径的要求,大大提高了算法便捷性。二是算法分两步进行,第一步针对主线道路服务,仅输入需要优化的道路的起止点,即可获得两点的最短路径;第二步针对支线道路服务,以第一步得到的主线道路为已有道路,只需要输入支线道路抹点(机位点坐标)坐标,即可自动寻索到该点距离主线道路的最短路径。研究结果可为实际的风电场建设前期工作提供重要的过程指导。

超大规模海上风电海陆一体直流输电技术探讨

海上风电的大规模开发是“双碳”战略目标实现的重要举措之一。常规的海上风电经柔性直流送出方案中,风电登陆后依赖交流架空线实现陆上电能传输,存在陆上输电走廊占用大、需要建设大量陆上换流站等不足,难以支撑我国海上风电资源大规模集中开发的需求。在分析我国海上风电开发需求的基础上,提出了超大规模海上风电海陆一体协同输电技术方案,为千万千瓦级海上风电基地开发提供一种新的解决思路。在PSCAD/EMTDC仿真平台上搭建了6000MW海上风电经三送、两受多端直流海陆一体送出系统模型,验证了所提技术方案的有效性和可行性。

基于无功就地平衡的风电场内部分散决策式精细化无功电压控制策略

“沙戈荒”大规模汇集系统远离主网,呈现出较强的无功电压敏感特性,风电场整体和内部的无功不平衡在并网送出线路和场内馈线上产生的压差较大,传统的风电场无功电压控制方案难以保证其安全经济运行,为此提出一种风电场内部分散决策式精细化的无功电压控制策略。从无功需求的物理本质出发,详细分析风电场内各元件的无功需求并给出具体计算方法,进而建立风电场分布式多中心无功平衡模型,以非迭代方式直接求解场内各无功电源的无功指令。为衡量场内馈线上不合理无功流动,定义分区无功穿越量的概念,并推导出其计算表达式。算例分析结果表明:风电场内部分散决策式精细化无功电压控制策略能够强化风电场内无功就地平衡,有效改善馈线电压分布,大幅减少馈线上的无功穿越和有功损耗,提高风电场并网运行的安全性与经济性。

沙戈荒大基地风电项目集电线路选型及优化研究

针对沙戈荒大基地风电项目的特殊气候与地质条件,系统进行了集电线路的选型与优化研究。首先,对集电线路的回路数量与路径进行了分析,根据负荷需求明确了回路划分原则;其次,依据载流量需求确定了导线截面,选定了适宜的杆塔型式与构造;再次,分析了地质条件,优化了基础型式以降低基础成本并提升稳定性;最后,研究了防风拉线金具的设计与固沙方案的实施。项目预测集电线路优化将实现成本节约并提高运行可靠性,为风电项目提供经济、有效的集电线路设计方案。

考虑集电系统元件故障的风电场可靠性评估

鉴于规划阶段对风电场运行可靠性评估的重要意义,以风电场的有功出力为研究对象,在分析风电场集电系统拓扑结构及元件可靠性模型的基础上,考虑了风速变化对系统可靠性指标的影响,设计了一种序贯蒙特卡洛法与深度优先路径搜索法相结合的风电场可靠性评估流程。通过算例分析比较了不同拓扑结构下风电场的可靠性指标,结果表明,相较于放射形拓扑,采用单边环形拓扑与双边环形拓扑结构的风电场等效停运率分别降低7.92%、7.79%,单边环形拓扑结构的可靠性最高,所建可靠性模型和评估方法有效可靠。

Collaborative Planning of Distributed Wind Power Generation and Distribution Network with Large-scale Heat Pumps

With the advancement of clean heating projects and the integration of large-scale distributed heat pumps into rural distribution networks in northern China,power grid companies face tremendous pressure to invest in power grid upgrades,which bring opportunities for renewable power generation integration.The combination of heating by distributed renewable energy with the flexible operation of heat pumps is a feasible alternative for dealing with grid reinforcement challenges resulting from heating electrification.In this paper,a mathematical model of the collaborative planning of distributed wind power generation(DWPG)and distribution network with large-scale heat pumps is developed.In this model,the operational flexibility of the heat pump load is fully considered and the requirements of a comfortable indoor temperature are met.By applying this model,the goals of not only increasing the profit of DWPG but also reducing the cost of the power grid upgrade can be achieved.

Probabilistic load flow method considering large-scale wind power integration

The increasing penetration of wind power brings great uncertainties into power systems,which poses challenges to system planning and operation.This paper proposes a novel probabilistic load flow(PLF)method based on clustering technique to handle large fluctuations from large-scale wind power integration.The traditional cumulant method(CM)for PLF is based on the linearization of load flow equations around the operation point,therefore resulting in significant errors when input random variables have large fluctuations.In the proposed method,the samples of wind power and loads are first generated by the inverse Nataf transformation and then clustered using an improved K-means algorithm to obtain input variable samples with small variances in each cluster.With such pre-processing,the cumulant method can be applied within each cluster to calculate cumulants of output random variables with improved accuracy.The results obtained in each cluster are combined according to the law of total probability to calculate the final cumulants of output random variables for the whole samples.The proposed method is validated on modified IEEE 9-bus and 118-bus test achieve a better performance with the consideration of both traditional CM,2 m+1 point estimate method(PEM),Monte Carlo simulation(MCS)and Latin hypercube sampling(LHS)based MCS,the proposed method can achieve a better performance with the consideration of bothcomputational efficiency and accuracy.

计及循环寿命和运营策略的风电汇集区域储能电站优化配置

风电汇集区域建设储能电站可在保证整个区域一次调频能力的同时提高经济性。针对风电汇集区域建设储能电站提出一种基于运营策略的储能容量配置方法。储能电站采用独立运营机制,在保证区域一次调频容量的前提下参与电力市场交易,实现储能利用率、效益最大化。提出储能电站运营配置协同优化双层模型,外层以全生命周期投资回报率最大为目标进行储能配置,内层计及储能循环寿命以日运行期望利润最大为目标优化运营策略,内外层联合优化达到综合最优,从而得出储能配置结果。提出一种改进麻雀搜索算法提高收敛速度,对双层配置模型进行求解。通过算例验证了所提方法能够在确保区域具备一次调频能力的同时提高储能的经济性。

载荷优化的海上漂浮式风电机组二阶滑模变桨控制

针对强非线性、强耦合的海上漂浮式风电机组动力学系统,提出一种基于二阶滑模的统一变桨控制策略,解决受海浪风速等随机干扰引起浮式支撑平台运动而产生的疲劳结构载荷及功率波动问题。构建漂浮式风电机组的不确定仿射非线性模型,基于风电机组“额定转速”设计积分滑模面,此“额定转速”不再是恒定值,而是取决于平台纵摇速度的变量,基于超螺旋算法实现二阶滑模变桨控制律。采用FAST和Matlab/Simulink联合仿真,所提出的方案与传统PI控制相比,对稳定高风速时风力发电机功率,抑制浮式支撑平台运动及减少叶根载荷具有更好的控制作用,对塔基也有较好的减载作用。

海上风电分频集电系统结构及其稳定运行影响因素仿真分析

近年来海上风电发展迅速,但普遍存在建设投资大且维护成本高的问题。本文提出了一种基于高压永磁同步发电机的分频集电系统结构,减少机端换流器数量和分频升压变压器环节,实现分频并网发电,并介绍了基于统一变流器的分频集电系统稳定控制策略。基于Matlab/Simulink搭建了含三台永磁同步发电机的分频集电仿真模型,并对影响系统稳定运行的风速差异和线路阻抗差异因素进行了仿真分析,仿真结果表明,三台风机在存在风速差异和线路阻抗差异的情况下能够稳定运行,验证了基于转子平均磁链控制的分频集电结构的有效性。

陆上风电直流汇集系统拓扑结构优化设计方法

陆上风电全直流发电系统可有效解决大规模风电交流汇集、传输产生的谐波谐振等问题,而经济、可靠的风电直流汇集系统拓扑结构是其良好发展的基础。文中首先给出基于风机分组串并联的风电直流汇集系统拓扑结构;其次,对该拓扑结构中的不同风机分组方案进行可靠性及经济性评估;然后,综合考虑系统经济性与可靠性问题带来的缺电损失成本,以总成本最低为目标,提出风电直流汇集系统拓扑结构优化模型;最后,以中国西北某50 MW风电场为例,对所提风电直流汇集系统拓扑结构优化模型进行仿真验证。结果表明,所提风电直流汇集系统拓扑结构优化方案可以统筹考虑系统经济性和可靠性,获得最优风机分组方案,将优选后的拓扑结构与典型风电交流汇集系统结构对比,验证了所提拓扑结构优化方案的可行性及优势。

海上风电直流汇集DC-DC变换器拓扑与控制策略分析

海上风能资源丰富,大规模远距离的海上风电是未来风力发电的趋势。作为风电直流汇集传输的核心设备,适用于高压大功率的DC/DC变换器研究尤为重要。已有的DC/DC变换器大多工作于中低压小功率环境,为此文章介绍了海上风电DC/DC变换器的技术需求,详述了适用于海上风电直流汇集的模块组合式DC/DC变换器拓扑结构、子拓扑结构、控制策略,总结分析了模块组合式DC/DC变换器需进一步研究的内容,为其应用于海上风电直流汇集提供了参考。