电力系统谐波分析的同步校正法

提出一种谐波分析的新方法——同步校正法,该方法采用恒定采样周期进行非同步采样,然后对非同步采样序列加权生成等价同步采样序列。在所关心的频率点上,等价同步采样序列的FFT与同步采样序列的FFT相同。生成等价同步采样序列的权系数来源于同步校正方程的解。该方法在线计算与常规的加窗相似,但后者每次加的是同一组权系数,前者则有许多组权系数供选择,其选择的依据是当前采样时段的信号频率。Matlab仿真和配电变压器监测终端中的应用都验证了所提方法的有效性。     

电力系统的安全分析

电力系统的安全稳定分析是电力系统规划和运行的主要任务之一.在原有的基础上新颁布的<电力系统安全稳定控制技术导则>规定了电力系统安全稳定控制的功能、应用条件、基本性能要求及主要技术指标.随着电网的发展,运行控制的复杂程度不断增加,依赖研究人员的运行经验有选择的进行分析的方法,已不能满足新导则的要求.     

谐波下的电能计量及电能质量分析方法

对谐波下电能计算和电能质量分析的方法进行了讨论,着重对积分电能算法和FFT变换方法进行了对比介绍。     

Analysis of even harmonics generation in an isolated electric power system

Harmonics bred from loads are mainly odd order because the current waveforms have half‐wave symmetry. Since the even harmonics are negligibly small, they generally are not measured in electric power systems. However, even harmonics were measured at a 500/275/154 kV substation in Hokuriku Electric Power Company after a transmission line fault was corrected. The even harmonics caused malfunctions of protective digital relays because the relays used 4th harmonics at the input filter as the automatic supervisory signal. This paper describes mechanisms of generation of the even harmonics by comparing the measured waveforms with the ATP‐EMTP simulation results. Analysis of these results has clearly shown that there are three different mechanisms of generation of even harmonics. The first mechanism is the appearance of a magnetizing current in transformers due to flux deviation by the DC component of the fault current. The second mechanism is harmonic conversion of a synchronous machine which generates even harmonics when the DC component or the even harmonic current flow into the machine. The third mechanism is an increase of harmonic impedance due to an isolated power system, thus producing the harmonic voltages. The design of the input filter of protective digital relays should take into account even harmonics generation in an isolated power system. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 167(2): 56–63, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20592     

电力系统谐波影响及治理探讨

对于产生大量谐波的用户,在用户变的低压侧加装滤波装置。改变部分运行、接线方式,减小谐波的产生、叠加、放大、产生危害的机会增加电网的短路容量、提高电气设备的短路比,来降低谐波对同一电网上其他设备的影响。     

Expert system for classification and analysis of power systemevents

This paper presents an expert system that is able to classify different types of power system events to the underlying causes (i.e., events) and offer useful information in terms of power quality. The expert system uses the voltage waveforms and distinguishes the different types of voltage dips (fault-induced, transformer saturation, induction motor starting) as well as interruptions (nonfault, fault-induced). A method for event-based classification is used, where a segmentation algorithm is first applied to divide waveforms into several possible events. The expert system is tested using real measurements and the results show that the system enables fast and accurate analysis of data from power quality monitors     

谐波在线预测系统的研制

基于“虚拟仪器”的概念,引入快速抗混迭傅里叶变换方法,用分段积分的方法取代快速傅里叶变换中离散序列求和方法进行复频谱系数的数值计算,提高了谐波测量精度并降低了硬件成本。提出一种自适应自回归(ADAR)预测模型,可根据谐波过程特性变化自适应调整自回归预测模型的参数乃至结构。描述了其预测方程,介绍了电力谐波在线分析预测系统的功能结构及软件设计。该系统能实时测量谐波,并可对设定次数谐波的未来状况作出在线短期预测。     

谐波分析的改进双峰谱线算法

加窗插值FFT是电力系统谐波分析常用算法,在此基础上的双峰谱线算法能够有效改善谐波数据准确度.但是该算法的分析精度很大程度上取决于信号频率校正系数α的计算精度,本文利用专用电能计量芯片ATT7022B准确测量出基波频率,在此基础上推导出α的简化算式,极大地降低了双峰谱线算法的计算量,并利用多项式逼近获得了幅值修正的计算公式,显著提高了谐波分析精度.最后通过仿真和实验结果验证了本文改进算法的有效性与易实现性.     

电力电子化机载电力系统稳定性分析

多电飞机由于越来越多地采用电能作为能源供给形式,其电力系统的稳定性愈加重要。电力电子技术的发展是推动多电飞机及飞机电力系统技术进步的重要力量之一。同时考虑交直流系统及其相互作用,建立包含发电机、自耦变压整流器、机电作动器在内的多电飞机电力系统平均值模型,力求简单准确且适合系统大扰动稳定性分析的需求;在此基础上,结合混合势函数理论和李雅普诺夫稳定性定理对系统的稳定域进行求解。仿真结果表明,所提出的大扰动稳定性分析方法准确、快速,能灵活分析各类参数对系统稳定性的影响。     

电力系统故障分析的相分量法研究

分析了对称分量法在三相不对称网络中存在的不足。研究了利用相分量计算电力系统不对称故障的方法，说明了该方法的实用价值。     

电力谐波动态监测系统的研究与设计

针对目前常见的检测方法中控制电路过于复杂的问题,文章提出采用以自适应噪声对消技术的神经元电力谐波动态检测方案。采用最小均方(LMS)算法,获得所需的检测谐波信号,利用高精度微型互感器实现信号采集,由DSP实现对电力谐波的动态检测,利用CAN总线实现数据的高速上传给上位机,完成谐波数据的综合处理。该系统已成功地在河南中孚铝厂投入运行,检测精度达到国家标准,具有较高的推广价值。     

Simulation and transient analysis of conventional and advanced aircraft electric power systems with harmonics mitigation

This paper presents the simulation and transient analysis of conventional and advanced aircraft electric power systems with harmonics mitigation. Complete modeling of aircraft electric power systems is proposed. The conventional aircraft electrical power system is analyzed considering equivalent passive AC and DC loads under transient and steady-state operating conditions. The electric power source is simulated to ensure constant frequency and voltage which meet the aircraft electrical standards for all loading cases. To mitigate the harmonics generated by the converters, passive input filters are designed to keep THD values within the standard limits. Furthermore, the advanced aircraft electrical system is simulated and analyzed under the same electric power source and loads. The results are compared to those of the conventional aircraft electric power system.     

对GPRS在电力系统应用的分析

论文分析了基于GPRS网络VPN的安全性和可靠性。作为电力通信的补充，对GPRS在电力系统应用的可行性进行了分析。     

电力系统谐波的一种新的单相检测法

在瞬时无功功率理论的基础上,针对一般基于d-q变换的检测方法不能检测不对称三相电流的谐波的缺点,提出了一种新的电网谐波检测方法。此方法属于单相检测法,先提取电网电流中的某相基波幅值,再将基波幅值乘以与该相电流同相位的正弦波,从而得出该相的瞬时基波电流。该方法相对简化了结构,并且采用了改进的算法,能很好地运用于单相电路和三相电路的谐波检测。仿真结果表明,在电网三相电流对称和不对称的两种情况下,这种方法都能保证检测的实时性和精确性。     

Neuro-evolutionary approaches to power system harmonics estimation

This paper focuses on exploiting two computational intelligence techniques such as artificial neural network and evolutionary computation techniques in estimation of harmonics in power system. Accurate estimation of harmonics in distorted power system current/voltage signal is essential to effectively design filters for eliminating harmonics. No standard design is available for handling of local minima and training of NN but Evolutionary Computation (EC) techniques are capable of resolving local minima. Neural Network and Evolutionary Computing (Bacterial Foraging Optimization (BFO)) are combined to achieve accurate estimation of different harmonics components of a distorted power system signal. First estimation of unknown parameters are carried out using BFO, then optimized output of BFO are taken as initial values of the unknown parameters for Adaline. Amplitude and phase of fundamental and harmonics components are determined from final updated values of unknown parameters using Adaline. This Adaline based Bacterial Foraging Optimization (Adaline-BFO) hybrid estimation algorithm addresses the problems of slow convergence and reduction of time generation of off-springs happening in Genetic Algorithm (GA), and to avoid local minima in Particle Swarm Optimization (PSO). The proposed Adaline-BFO algorithm has been applied for estimation of harmonics of the voltage obtained across the inverter terminals of a prototype Photovoltaic (PV) system. From the obtained results, it is confirmed that the proposed Adaline-BFO algorithm provides superior estimation performance in terms of improvement in % error in estimation, processing time in computation and performance in presence of inter and sub-harmonic components when compared with the Discrete Fourier Transform (DFT), Kalman Filter (KF) and BFO algorithms.     

Decentralized system identification for electric power system

Research on decentralized control of an electric power system is important for stabilizing control problems. In particular, since an electric power system is a large-scale nonlinear control system, decentralized (not divided) systems with cooperation should be constructed. This paper presents ways to construct decentralized systems for an electric power system. In section 2, swing data of a three-machine model system are obtained, in section 3, coefficient parameters of the model equation based on one-machine infinite-bus system with AVR and GOV are estimated by the least square method. In section 4, the equivalence calculated using estimated values is discussed, and the effect of conditions on fault is considered. Finally, section 5 is devoted to summarizing results of decentralized system identification.     

电力系统谐波的一种新的单相检测法

在瞬时无功功率理论的基础上,针对一般基于d-q变换的检测方法不能检测不对称三相电流的谐波的缺点,提出了一种新的电网谐波检测方法.此方法属于单相检测法,先提取电网电流中的某相基波幅值,再将基波幅值乘以与该相电流同相位的正弦波,从而得出该相的瞬时基波电流.该方法相对简化了结构,并且采用了改进的算法,能很好地运用于单相电路和三相电路的谐波检测.仿真结果表明,在电网三相电流对称和不对称的两种情况下,这种方法都能保证检测的实时性和精确性.     

台风对电力系统连锁故障的影响分析

在分析连锁故障现有模型的基础上,在多时间尺度连锁故障预测模型中考虑台风对线路故障概率的动态影响,建立台风变化过程与连锁故障事故链的配合关系。考虑台风影响下的线路故障概率,构造初始故障集;结合天气因素、线路负载率和潮流波动率等因素构造关联性指标,利用聚类方法选取关联性指标高的线路作为下一级故障线路,模拟重载等因素引起的线路随机开断;将基于潮流追踪的切机切负荷与发电机调整相结合,用于线路一般过载的控制,并计算事故链的概率和风险;最后以IEEE 39节点系统为例,说明台风对系统关键线路和事故链的影响、基于潮流追踪的切机切负荷控制的作用和提高线路设计风速的可能性,并验证了所提模型和算法的合理性。     

电力谐波对电能计量影响的分析与探讨

在电力系统中,由于非线性用户向电网注入大量的谐波,谐波不仅影响电能质量,同时造成电力部门电能计量表计漏计,本文试从电能的计算原理和电能表的计费原理上探讨谐波造成计量漏计的原因,建议时非线性负载用户的谐波进行综合治理,并采用高精度的电子式电能计费表计,用户和供电部门都能获得很好的经济效益.     

电力通信反事故分析系统的研发和应用

介绍了电力通信反事故分析系统,该系统可以为电力通信人员提供一个综合演练平台,同时提高通信管理水平。文章分析了该系统的组织结构和关键技术,描述了系统在培训、反事故演练、考评等方面的主要功能。该系统在电力通信领域具有一定的推广应用价值。