转子振动信号同步整周期重采样方法的研究

提出了应用微分和样条插值的转子振动信号同步整周期重采样方法,该方法所用的信号为等时间间隔同步采集的键相信号和振动信号.对键相信号进行微分处理,获得相对幅值较大的周期起止点,然后把振动信号用三次样条在起止点间进行等数量插值,从而获得了同步整周期采样的数据.研究结果表明:该方法能准确地对振动信号进行同步整周期重采样,具有对信号采集设备要求低、相位误差小的优点,可广泛用于转子振动信号整周期采样领域.     

一种非同步采样下的介损测量方法

由于电力系统频率波动的影响，用于测量介损的谐波分析法很难满足整周期采样，产生的泄露误差将影响基波相位测量的精度。分析了频谱泄露和栅栏效应产生的原理。为了提高谐波分析法的计算精度，对谐波分析法进行了改进，并与未改进方法进行了对比，并用MATLAB软件进行了仿真，通过仿真证明了方法的有效性。     

电力系统中非同步采样误差的研究

由于实际电网信号的频率通常会在额定频率附近波动,很难保证对信号的同步采样,FFT算法的泄漏现象和栅栏效应将会导致较大的测量误差。从软、硬件两个方面综合分析了几种常用的预防、补偿措施的优缺点,表明这些方法提高了信号的分析精度和测量参数的可信度。     

DSP在电力参数检测系统中的应用

设计了一种基于TMS320F2812DSP电力参数实时检测系统。采用ADS8364对6路信号同时采样,利用复序列FFT算法得到各种电力参数,可由CAN总线与上位机实时传输数据,实现对电力系统的实时、准确的参数测量和数据分析。采用了硬件锁相环技术。可更加有效实现同步采样,提高了采样精度。     

交流采样测量装置的在线实时误差监测系统

交流采样测量装置可快速,准确地采集各种电力参数.是实现电力调度自动化、电气参数在线实时监控的重要计量设备,介绍了该装置监测系统的基本原理、软硬件设计,提出了确保计量设备准确度和稳定性的技术措施,应用了电流回路不开路、电压回路不短路保护技术实例运行结果,实现了交流采样测量装置实时误差的在线校验、自动校验和远程监测.     

基于实时同步数据采集的内燃机燃烧分析系统的研制

介绍了基于实时同步的内燃机数据采集系统的结构、工作原理、功能和特点。本系统采用工业控制计算机和应用软件固化运行方式,提高了系统的抗干扰和抗病毒能力;采用自行设计的硬件电路配以自己开发的软件,形成了新型的DMA技术,使内燃机的多路参数能同时采样,提高了系统的测量精度和分析精度。     

基于PCC的交流采样的设计与实现

交流采样是按一定规律对被测信号的瞬时值进行采样．再按一定算法进行数值处理,从而获得所需电量信息的测量方法,可省去电量变送器等硬件设备、减少装置的体积、用软件功能代替其硬件功能、降低了系统成本、提高了实时性、保证了对交流电参量的采集精度和稳定性。应用B＆R的2005系列的IP161模块实现交流采样,介绍了硬件设计、工作原理及几项关键技术。     

正确使用全站仪补偿器 提高测量精度

正确使用全站仪补偿器，减少测量仪器的三轴误差，提高测量精度。     

插值算法在内燃机瞬时转速测量中的应用研究

提出了采样信号的插值计算公式 ;考虑到测量信号中调制现象的影响 ,提出了插值法在瞬时转速计算中的误差公式 ;并针对 6 - 135 G柴油机最高转速对两点插值和三点插值的精度进行了计算 ;最后用实测数据进行了验证。结果表明这是提高瞬时转速测量精度的一种有效方法 ,在 5 0 k Hz的低采样率下即可得到较平滑的瞬时转速波形。     

基于跟踪偏差角和改进迭代误差修正的光伏功率预测优化策略

随着光伏发电逐渐接入电网,电网对光伏功率的预测精度也提出了更高的要求。针对双轴太阳能自动跟踪系统实际运行中存在的跟踪偏差角以及采用传统迭代误差修正思想进行多模型预测时存在的误差异常值,提出一种基于跟踪偏差角和改进迭代误差修正的光伏功率预测模型。首先,建立改进迭代误差修正模型;然后,利用改进迭代误差修正模型对功率预测进行一层优化;最后,结合跟踪偏差角完成对光伏功率预测的二层优化。仿真结果表明,所建立的光伏功率预测模型能使功率预测精度提高5%左右,弥补了单一模型存在的不足。     

Variability and uncertainty of wind power in the California electric power system

The California generation fleet manages the existing variability and uncertainty in the demand for electric power (load). When wind power is added, the dispatchable generators manage the variability and uncertainty of the net load (load minus wind power). The variability and uncertainty of the load and the net load are compared when 8790 MW of wind power are added to the California power system, a level expected when California achieves its 33% renewable portfolio standard, using a data set of 26,296 h of synchronous historic load and modeled historic wind power output. Variability was calculated as the rate of change in power generated by wind farms or consumed by the load from 1 h to the next (MW/h). Uncertainty was calculated as the 1 h ahead forecast error [MW] of the wind power or of the load. The data show that wind power adds no additional variability than is already present in the load variability. However, wind power adds additional uncertainty through increased forecast errors in the net load compared with the load. Forecast errors in the net load increase 18.7% for negative forecast errors (actual less than forecast) and 5.4% for positive forecast errors (actual greater than forecast). The increase in negative forecast errors occurs only during the afternoon hours when negative load forecasts and positive wind forecasts are strongly correlated. Managing the integration of wind power in the California power system should focus on reducing wind power forecast uncertainty for wind ramp ups during the afternoon hours. Copyright © 2013 John Wiley & Sons, Ltd.     

有功分级平滑修正风电出力短期预测精度

为达到国家电网要求的风电场短期预测(日前)误差不超过25％的技术规定,文章以15 min时间间隔的风电实测和预测功率历史数据为基础,从横向误差和纵向误差的角度,提出了一种利用横向一次修正和储能系统二次修正的有功分级平滑来提高风电功率短期预测精度的方法.通过对误差时间序列进行统计分析,得出所需的横向时间向量将0～24 h预测功率前后平移,实现初级修正;运用储能系统装置,制定储能系统能量管理策略,有效地补偿风电功率的纵向误差,实现二级修正.以风电场的典型历史数据为例,经过两级有功分级修正,对风电功率预测进行较精确评估,同时做了简易的经济评价.     

Reactive power compensation of an isolated hybrid power system with load interaction using ANFIS tuned STATCOM

This paper presents an adaptive neuro fuzzy interference system (ANFIS) based approach to tune the parameters of the static synchronous compensator (STATCOM) with frequent disturbances in load model and power input of a wind-diesel based isolated hybrid power system (IHPS). In literature, proportional integral (PI) based controller constants are optimized for voltage stability in hybrid systems due to the interaction of load disturbances and input power disturbances. These conventional controlling techniques use the integral square error (ISE) criterion with an open loop load model. An ANFIS tuned constants of a STATCOM controller for controlling the reactive power requirement to stabilize the voltage variation is proposed in the paper. Moreover, the interaction between the load and the isolated power system is developed in terms of closed loop load interaction with the system. Furthermore, a comparison of transient responses of IHPS is also presented when the system has only the STATCOM and the static compensation requirement of the induction generator is fulfilled by the fixed capacitor, dynamic compensation requirement, meanwhile, is ful-filled by STATCOM. The model is tested for a 1% step increase in reactive power load demand at t = 0 s and then a sudden change of 3% from the 1% at t = 0.01 s for a 1% step increase in power input at variable wind speed model.     

基于光滑自助法的风功率预测误差核密度建模方法

在风功率预测误差建模应用中,无偏交叉验证(UCV)和经验法则(ROT)是两种常用的非参数方法。然而,由于风功率预测误差中存在的尖峰厚尾,以及局部小样本特征,直接使用这两种方法会产生较大的泛化误差。为了使UCV和ROT在应用中发挥更好的作用,文章提出了一种基于光滑自助法的核密度估计方法。该方法利用了光滑自助法在分位数推断上的优势,通过修改平均积分平方误差(MISE)指标函数,实现了对基本估计方法的校正。该方法本质上是一种装袋方法,可以与任何基本的核密度方法结合使用。在实例仿真中,得到了SBUCV方法和SBROT方法的运行结果,并与UCV和ROT方法的结果进行了对比。仿真结果表明了该方法的有效性。     

Characteristics of day‐ahead wind power forecast errors in Nordic countries and benefits of aggregation

The growing proportion of wind power in the Nordic power system increases day‐ahead forecasting errors, which have a link to the rising need for balancing power. However, having a large interconnected synchronous power system has its benefits, because it enables to aggregate imbalances from large geographical areas. In this paper, day‐ahead forecast errors from four Nordic countries and the impacts of wind power plant dispersion on forecast errors in areas of different sizes are studied. The forecast accuracy in different regions depends on the amount of the total wind power capacity in the region, how dispersed the capacity is and the forecast model applied. Further, there is a saturation effect involved, after which the reduction in the relative forecast error is not very large anymore. The correlations of day‐ahead forecast errors between areas decline rapidly when the distance increases. All error statistics show a strong decreasing trend up to the area sizes of 50,000 km². The average mean absolute error (MAE) in different regions is 5.7% of installed capacity. However, MAE of a smaller area can be over 8% of the capacity, but when all the Nordic regions are aggregated together, the capacity‐normalized MAE decreases to 2.5%. The average of the largest errors for different regions is 39.8% and when looking at the largest forecast errors for smaller areas, the largest errors can exceed 80% of the installed capacity, whereas at the Nordic level, the maximum forecast error is only 13.5% of the installed capacity. Copyright © 2016 John Wiley & Sons, Ltd.     

A control strategy for energy storage system based on wind power prediction error interval

由于风能的间歇性和随机性,风电功率预测的精度依然较低。随着大规模风电的集中接入,不确定性风电功率并网运行会加重电力系统的调控负担,同时会对日前调度计划安排带来不利影响。储能系统具有对功率和能量的时间迁移能力,被认为是平抑风电功率波动性、提高风电功率确定性的有效手段。本文从电力系统安全角度分析了制约风电上网规模的原因,使用基于时间序列的自回归模型预测风电功率,提出利用储能平抑风电功率预测误差区间的方法,对比考虑最大预测误差的传统调度方法,采用风电平均入网容量、风电发电量、电网空间利用率等评价指标评估所提出方法的有效性。     

地形复杂的风电场资源评估误差分析方法

由于计算模型本身的限制,风能资源地图分析与应用程序(WAsP)不能准确模拟复杂地形中风的流动变化情况,用其评价复杂地形风电场的风能资源时存在一定误差.目前,主要采用RIX方法来评估WAsP在复杂地形中的风速预测误差,长期以来一直缺少根据风速预测误差来评估风电场发电量预测误差的有效方法.文章在RIX方法的基础上,对WAsP应用于复杂地形风电场发电量预测的误差进行了研究,结合工程实践提出了一种发电量误差评估方法;根据某风电场实际发电量数据对提出的评估方法进行了验证,证明其有效性和实用性.     

Design and analysis of a wireless power transfer system with alignment errors for electrical vehicle applications

In this study, a 15 kW wireless power transfer system with high frequency and large air gap for electrical vehicle battery charge systems is designed and co-simulations with ANSYS-Maxwell and Simplorer software are performed. The air gap between the primary and the secondary windings are determined as 20 cm for the 15 kW wireless power transfer system. Operation of the designed system for different operation conditions such as completely aligned windings (ideal condition) and windings with alignment errors, which can occur because of user error or another reason, are analyzed and obtained results are reported. The resonant frequency of the designed system which has a 60 × 60 cm secondary winding and a 60 × 100 cm primary winding is 17.702 kHz, and the maximum efficiency of the system is obtained as 75.38% for completely aligned windings. The distribution and density of the electromagnetic flux, and variation of efficiency versus load level of the system and responses of the system in case of different alignment errors are also investigated and reported for both ideal operation conditions and in case of alignment errors.     

风电系统的无功功率与电网电压稳定

论述了风电容量在占局部电网相当比例时,风电机组的无功功率调整与电网电压之间的关系,对于定速和变速风电机组的运行特性做了分析,提出了在需要做无功功率调整时风电机组应能满足的特殊要求。