考虑集电网络的风电场建模研究

为提高风电场模型的精度,文章提出建立一种考虑到集电网络影响的模型方法,该模型采用猴群算法计算等值参数。在此模型的基础上对风电场进一步化简,采用基于扩散距离的谱聚类算法对风电机组进行动态分群,得到两机表征的风电场模型,并进行仿真建模过程。通过对一个12 MW的详细风电场模型的仿真分析,将几种模型分别进行了对比,实验结果表明,文章提出的方法是准确有效的,所得到的两机表征模型能很好的反映出风电场并网的动态特性。     

风电场恒速发电机动态等值参数聚合的研究

风电场发电机数量众多,在研究含有大规模风电机组的电力系统稳定性时,为减少仿真计算量和时间,可采取动态等值的方法对风电场进行简化,为此提出了基于改进加权法的恒速风力发电机参数聚合实用化方法.在MATLAB/SIMULINK工具箱中对一实例系统进行建模和仿真,结果表明了该等值方法的正确性、精确性、简便性和有效性,为大规模并网型风电场的进一步研究提供了有利条件.     

基于RTDS的风电场等值建模与验证分析

针对风电场运行条件复杂、运行工况动态变化导致风电场输出功率的分散性问题,采用数理统计方法对风电场外特性进行稳态等值,考虑到大型风电场所处地形复杂、机群分布不规则带来的风速差异性问题,以风电场内长时间尺度实测风速数据作为特征变量,采用改进动态聚类算法进行机群划分,进而基于风电场参数对等值机模型的参数进行聚合辨识。基于RTDS实时数字建模及仿真试验分析结果表明,建立的风电场等值模型能够准确地反映风电场在不同风速及电网侧短路故障下的动态特性,可用于含双馈风电机组风电场接入电力系统稳定性分析。     

考虑地形因素的风电场动态同调分群方法研究

针对传统风电场动态等值方法因不考虑复杂地形影响而出现的等值精度偏低的问题,文章提出了一种基于双馈风电机组同调判别的风电场动态分群方法。首先,分析了地形因素对风电场输入风速及风电机组动态特性的影响,其中包括风速分布的影响、尾流效应的影响、机组不规则排布造成的集电线路阻抗影响等;然后,通过分析双馈风电机组多阶模型的特征量对其主导模式的影响作用,提出了以机组转子电流作为观测量进行同调性判别,并根据风电场内各台机组的转子电流动态受扰轨线相似度,利用层级聚类算法完成对场内机组的分群聚类。仿真结果验证了文章所提出方法的有效性。     

大型风电场失速型机组等值建模的研究

对于风电场中失速型机组的多机等值,采用异步发电机的机电暂态模型求解发电机组的等值电气参数,利用基于传递函数概念的参数辨识方法及最小二乘法求解发电机组的动态等值参数。利用系统等值得结果对一实例进行仿真,结果表明了等值方法的有效性和正确性,为今后研究风电场与电网之间的相互影响提供了良好的模型基础。     

基于改进遗传KM聚类算法的风电场机群划分方法

为准确分析风电场的动态特性,借助同调等值法的思想,提出了一种基于改进遗传KM聚类算法的机群划分方法。此方法通过构造有效的适应度函数,结合K-means聚类算法和遗传聚类算法的优点,以实测风速数据为分群指标,对风电场进行机群划分。将同群风电机组等值为1台风电机组,建立风电场动态等值模型,并与传统单机等值模型和K-means等值模型进行了比较分析。以某风电场为例进行的仿真验证结果表明,采用所提方法建立的等值模型能够较为准确地反映风电场的动态响应特性,从而提高等值模型的精确性。     

基于改进猴群算法的山地风电场建模研究

根据风电场等值建模理论,利用风电场的详细模型,提出了一种基于改进猴群算法的山地风电场建模方法,并在Matlab/Simulink环境下建立一个9 MW的小型风电场进行了仿真实验。通过三种风速下的仿真结果表明,基于改进猴群算法的单机等值模型和详细模型具有基本一致的运行特性,可以更加简单方便地得到风电场的模型,这为大型山地风电场的等值建模提供了基础。     

考虑尾流效应及连接架构的风电场等值方法研究北大核心CSCD

对大型风电场进行完整的仿真分析会消耗巨大的时间成本。文章提出了一种基于尾流效应和连接架构的风电场等值法,考虑了风机位置对输入风速的影响,最大程度地保留了原有结构和性能,建立了简单准确的等值模型。分析了容量加权法的误差及原因,提出了根据风电场连接架构对风机群进行考虑尾流效应的分组方法,并通过容量加权法对分组进行参数聚合。通过Matlab/Simulink建立仿真模型,结果表明,所提模型的各项性能在不同风向下均能与原模型性能相近,具有较高的精确度和适应度。     

基于改进D-K聚类算法的直驱型风电场动态等值建模

研究永磁同步发电机(PMSG)的低电压穿越(LVRT)特性,提出一种基于改进D-K聚类算法的直驱型风电场等值建模方法。首先,根据风电场内各台PMSG卸荷电路的导通情况对风电场进行首次分群。其次,将卸荷电路未导通的PMSG故障期间的机端电压值作为分群指标,应用改进D-K聚类算法对风电场进行聚类等值。该算法解决了传统K-均值聚类算法k值需提前给定和依赖于初始聚类中心的问题。最后,以某实际风电场为例进行仿真分析,结果表明该等值模型与传统等值模型相比能更准确地反映直驱型风电场的动态和暂态运行特性。     

基于概率分析的风电场电压跌落评估方法研究

首先介绍双馈风力机的简化短路计算模型、风速分布模型以及母线/线路短路故障模型;其次针对风电场电压跌落问题,提出年电压跌落频次、电压跌落风险、与低电压穿越期望3个表征电压跌落的风险指标;接着基于Digsilent的DPL语言编写风电场电压跌落评估程序;最后对算例风电场进行仿真验证,针对风电场内外发生的不同类型短路故障发生后,造成的电压跌落风险进行分析,仿真结果可验证所提评估方法的有效性。     

Dynamic models of wind farms with fixed speed wind turbines

The increasing wind power penetration on power systems requires the development of adequate wind farms models for representing the dynamic behaviour of wind farms on power systems. The behaviour of a wind farm can be represented by a detailed model including the modelling of all wind turbines and the wind farm electrical network. But this detailed model presents a high order model if a wind farm with high number of wind turbines is modelled and therefore the simulation time is long. The development of equivalent wind farm models enables the model order and the computation time to be reduced when the impact of wind farms on power systems is studied. In this paper, equivalent models of wind farms with fixed speed wind turbines are proposed by aggregating wind turbines into an equivalent wind turbine that operates on an equivalent wind farm electrical network. Two equivalent wind turbines have been developed: one for aggregated wind turbines with similar winds, and another for aggregated wind turbines under any incoming wind, even with different incoming winds.The proposed equivalent models provide high accuracy for representing the dynamic response of wind farm on power system simulations with an important reduction of model order and simulation time compare to that of the complete wind farm modelled by the detailed model.     

Aggregated dynamic model for wind farms with doubly fed induction generator wind turbines

As a result of increasing wind farms penetration in power systems, the wind farms begin to influence power system, and thus the modelling of wind farms has become an interesting research topic. Nowadays, doubly fed induction generator based on wind turbine is the most widely used technology for wind farms due to its main advantages such as high-energy efficiency and controllability, and improved power quality. When the impact of a wind farm on power systems is studied, the behavior of the wind farm at the point common coupling to grid can be represented by an equivalent model derived from the aggregation of wind turbines into an equivalent wind turbine, instead of the complete model including the modelling of all the wind turbines. In this paper, a new equivalent model of wind farms with doubly fed induction generator wind turbines is proposed to represent the collective response of the wind farm by one single equivalent wind turbine, even although the aggregated wind turbines operate receiving different incoming winds. The effectiveness of the equivalent model to represent the collective response of the wind farm is demonstrated by comparing the simulation results of equivalent and complete models both during normal operation and grid disturbances.     

计及随机波动风速、风向的风电场建模方法研究

提出风电场建模方法建立风电场随机模型,对风电场运行特性进行仿真,为实现大规模风力发电的可预测、可控制目标服务。通过对风电场等值模型与详细模型的仿真比较,验证建模方法的合理性,并得出在研究风电场动态特性及其对电网影响时应考虑风速、风向的随机波动建立风电场模型。     

大规模并网型风电场等值建模研究现状

风电场等值模型的建立有助于对含有大规模风电接入的电网进行稳态运行以及各种稳定性问题的分析研究。介绍了风电场等值建模的基本思想,基于国内外关于大规模并网型风电场等值建模的研究现状,对风电场稳态和动态的各种等值建模法进行了简要的分析和综述。     

Modeling of the dynamics of wind to power conversion including high wind speed behavior

This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state‐of‐the‐art is to use static power curves for the purpose of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind speed shutdowns and restarts are represented as on–off switching rules that govern the output of the wind turbine at extreme wind speed conditions. The model uses the concept of equivalent wind speed, estimated from the single point (hub height) wind speed using a second‐order dynamic filter that is derived from an admittance function. The equivalent wind speed is a representation of the averaging of the wind speeds over the wind turbine rotor plane and is used as input to the static power curve to get the output power. The proposed wind turbine model is validated for the whole operating range using measurements available from the DONG Energy offshore wind farm Horns Rev 2. Copyright © 2015 John Wiley & Sons, Ltd.     

Multi-machine transient modelling of wind farms: An essential approach to the study of fault conditions in the distribution network

This paper reports the study carried out to asses the dynamic behaviour of a real wind farm during fault conditions in the distribution network. The objective is to obtain a transient model valuable for all kinds of operational conditions. The paper begins with a detailed modelling of the distribution network between the wind farm common busbar and the point of common coupling with the HV transmission system, for all types of short-circuits. The state-space network model, together with the electromagnetic transient model of each wind generator, configure a multi-machine wind farm model, with 572 state variables. Simulation results prove that multi-machine modelling is mandatory in order to tackle the wind farm contribution to symmetric and asymmetric short-circuits.     

Aggregated models of permanent magnet synchronous generators wind farms

This paper evaluates the responses of three aggregated models of a wind farm consisting of variable speed permanent magnet synchronous generator wind turbines when wind fluctuations or grid disturbances occur. These responses are compared with those of the detailed wind farm model, in order to verify the effectiveness of the studied aggregation methods for this type of wind farms. The equivalent wind farm models have been developed by adapting different aggregation criteria that already exist in technical literature and had been applied to other technologies. In this work, these methods have been modified to suit them to the permanent magnet synchronous generator technology. The results show that the three aggregated models provide very similar results to the detailed model, both in the evolution of active power when fluctuations in wind speed occur, and in the active power and DC-link voltage during the two simulated voltage dips. Notably, the aggregated model with an approximate mechanical torque offers excellent results.     

Modelling wind farms for grid disturbance studies

This paper analyses the simplest representation of generators on wind turbine modelling, giving the accuracy required in power system disturbance studies. The order of the generator model and the numerical integration methods employed are compared.To avoid the use of a detailed model of a wind farm, several aggregated models can be found in the literature. This paper analyses the influence of the wind farm internal network in the accuracy of the results and proposes a new equivalent model to represent the dynamic response of wind farms. The proposed aggregated model considers a weighted average where the transported power is used as weighting factor in order to ameliorate the accuracy on grid disturbance simulations.