Analysis and synthesis of sliding mode control for large scale variable speed wind turbine for power optimization

The problem of designing a nonlinear feedback control scheme for variable speed wind turbines, without wind speed measurements, in below rated wind conditions was addressed. The objective is to operate the wind turbines in order to have maximum wind power extraction while also the mechanical loads are reduced. Two control strategies were proposed seeking a better performance. The first strategy uses a tracking controller that ensures the optimal angular velocity for the rotor. The second strategy uses a Maximum Power Point Tracking (MPPT) algorithm while a non-homogeneous quasi-continuous high-order sliding mode controller is applied to ensure the power tracking. Two algorithms were developed to solve the tracking control problem for the first strategy. The first one is a sliding mode output feedback torque controller combined with a wind speed estimator. The second algorithm is a quasi-continuous high-order sliding mode controller to ensure the speed tracking. The proposed controllers are compared with existing control strategies and their performance is validated using a FAST model based on the Controls Advanced Research Turbine (CART). The controllers show a good performance in terms of energy extraction and load reduction.     

复合绝缘子自然污秽与人工污秽试验的等价性分析

为了研究实际高海拔条件下复合绝缘子自然污秽与人工污秽试验的差异,给高海拔地区直流输电线路的外绝缘设计提供参考,在高海拔条件下,对绝缘高度为1.9m、伞形结构为一大一小的复合绝缘子进行不同附灰密度、不同污秽分布以及盐的不同成分的人工污秽试验,揭示灰密、污秽分布和盐的成分等因素对复合绝缘子直流污闪特性的影响。试验发现,盐密一定、灰密≤1.0mg/cm2的条件下,灰密修正系数与附灰密度成负幂函数关系;灰密一定的条件下,污闪电压随污秽分布不均匀程度的增加而增加;盐密一定的条件下,盐种类的修正系数与CaSO4贡献率成指数关系。因此,在估算自然污秽条件下复合绝缘子的直流污闪电压及实际工程外绝缘配置时要充分考虑这些因素的影响。     

HVDC地中直流对交流系统影响的防范措施

针对直流输电系统处于单极大地回路运行方式时对交流电网运行带来的噪声、谐波、振动等不利影响,比较全面地对各种抑制地中直流影响的措施进行了对比分析。基于地中电流的成因与流散规律分析,提出了采用直流接地极与交流变电站选址优化、无接地极运行或多极共址运行方式、合理结构型式变压器的选择等主动防范措施减小地中直流的影响。结合作者的研究成果,就国内外目前抑制变压器中性点直流采取的注入反向电流、中性点串入电容、中性点串入电阻等措施进行了对比分析。通过分析串电阻措施的关键问题,认为该方案结构简洁,长期运行可靠性高,不会产生谐振,成本低廉,建议在现场使用。该研究成果为解决交直流电网并列运行安全稳定运行提供了有益的建议。     

基于分层判别的广域继电保护系统

基于现有广域保护系统模型,提出了区域性两层式的广域保护算法。第一层采用优化算法进行故障判别：根据广域系统中方向元件的特性,定义了方向元件的正、反方向以及各设备的期望状态函数,得到优化算法目标函数的一般形式;在此基础上,针对3/2接线,对中开关方向元件模型做了特殊处理。第二层采用电流矢量和判别：对于因个别方向元件数据丢失造成故障判断错误的情况,借助广域保护系统冗余性,采用电流矢量和进行辅助判断,能有效排除非故障元件。仿真结果证明：该方案具有良好的效果,在多个方向元件数据丢失的极端情况下仍能正确动作。     

Hybrid-model transient stability simulation using dynamic phasors based HVDC system model

A novel hybrid-model transient stability simulation algorithm for ac/dc power systems is suggested in this paper, where dynamic phasors theory is applied for HVDC transmission system modeling, and traditional electromechanical transient models are used for ac system. A detailed dynamic-phasors-based HVDC system model is derived first, and the algorithm for interface of the dc dynamic phasors model to ac network is proposed next. Computer simulation results show that the HVDC dynamic phasors model has very good accuracy as compared with its electromagnetic transient model; the test results from a 2-area ac/dc power system and a multi-infeed HVDC power system show clearly that the suggested interface algorithm works effectively in system transient stability analysis. The proposed hybrid-model simulation algorithm provides a new approach for dynamic simulation of large-scale ac/dc power systems.     

基于W-BiLSTM的可再生能源超短期发电功率预测方法

针对现有新能源超短期预测方法难以有效挖掘和分析数据的固有波动规律,且当时序过长时易丢失重要信息等问题,提出了一种基于注意力(Attention)机制的小波分解-双向长短时记忆网络(W-BiLSTM)超短期风、光发电功率预测方法.首先,利用小波分解提取输入时间序列的时域信息和频域信息.随后,考虑双向信息流,采用双向长短时记忆网络(BiLSTM)进行预测,引入注意力机制,通过映射加权和学习参数矩阵赋予BiLSTM隐含状态不同的权重,有选择性地获取更多有效信息.最后,通过实际数据进行仿真验证.仿真结果表明,所提模型与现有模型相比,具有良好的预测性能.     

面向高比例可再生能源的输电网规划方法研究进展与展望

为应对高比例可再生能源接入带来的消纳问题,提出了以多场景技术、鲁棒优化技术和协同规划技术为核心的输电网规划理论,涵盖不同适用条件或需求场景下的4种不同规划方法,即基于多场景的输电网随机规划方法、基于概率驱动的输电网鲁棒规划方法、考虑多源互补的网-源协同规划方法以及与配电网相协同的输电网规划方法,能够从输电网规划的角度在安全稳定前提下提高可再生能源消纳能力.在此基础上,对未来输电网规划方法进行了展望,提出了满足更高安全稳定需求、协同更广泛的源-网-荷-储柔性互动、推动大数据应用和挖掘电力市场机制激励空间的可能研究方向,并探讨了研究难点和解决方式.     

适应中国电力现货市场发展的容量补偿机制初探

容量机制是现货市场发展的重要补充,高效的容量补偿机制设计是保障现货市场平稳运行,稳定发电机组营收能力,促进电力系统充裕度的重要措施。文中首先论述了现货市场的收入缺失问题以及大规模可再生能源对现货市场的冲击,论证了容量补偿机制的必要性。然后,总结了主流容量补偿机制(稀缺电价、容量补贴以及容量市场机制)的发展现状及近期效果,并讨论了容量补贴机制的执行流程、定价方法以及机制设计中的关键问题,介绍了容量市场框架、市场组织、关键参数设计方式以及相关影响因素。最后为中国容量补偿机制的发展提出了意见。     

Predicting lightning outages of transmission lines using generalized regression neural network

Lightning is the major cause of transmission line outages, which can result in large area blackouts of power systems. One effective method to prevent catastrophic consequences is to predict lightning outages before they occur. The abundance of recorded lightning and lightning outage data in power system makes it possible to predict lightning outages of transmission lines. This paper proposes an artificially intelligent algorithm using general regression neural networks (GRNN) to predict lightning outages of transmission lines. First, the data that can be obtained from the operation and management system of a power company are analyzed, and the features that can be used as input parameters of GRNN are extracted. The prediction model based on GRNN is then built to perform lightning outage prediction. Finally, the effectiveness of the proposed method is validated by comparing it with (Back Propagation) BP and (Radial Basis Function) RBF neural networks using actual lightning data and lightning outage data. The simulation results show that the proposed method provides much better prediction performance.