港口配电系统谐波分析及其治理措施

介绍了港口配电系统的谐波源及其特点,实际测量谐波源的谐波数据分析,港口谐波治理措施。     

Suppression of higher harmonics resonance in a distribution system

There are many PWM control devices, which are higher harmonics current sources, in distribution systems, and higher harmonics cause overcurrents by parallel resonance. To avoid overcurrents, it is necessary to suppress resonance. In this paper, a new suppression method, which uses the effect of source connected points in resonance circuits, is proposed. First it shows that the optimal point, which gives a minimum current amplification degree, is orthogonal to the static condenser voltage. Then, using the eigenvector of the state equation, the participation factor is defined. When the participation factor is zero, the orthogonality condition is introduced. Therefore, the optimal point is obtained with the participation factor. Finally, numerical investigation shows that multiple optimal points usually exist. Therefore, we can choose the most advantageous point as a source‐connected node. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(1): 18–29, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22307     

基于DFT的电力系统频率及谐波精确算法

频率是电力系统运行特性评估中最重要的参数之一。传统频率测量算法存在不同程度的误差,而它所带来的频谱泄露则影响谐波测量的精度。提出基于离散傅里叶变换（DFT）的改进测频算法,该算法利用相隔半个周波的3组信号数据求取2个修正系数,分别对相邻两个周波的相角进行修正,再通过其相角差求得实际频率。在此基础上,通过实时修正采样频率实现同步采样,从而精确进行谐波分析。4种不同情况的仿真实验结果表明算法具有较好的频率跟踪效果和谐波测量精度。     

Experimental verification of the effect of a voltage‐detection‐based shunt active filter for harmonic damping throughout a power distribution line

This paper is focused on a voltage‐detection‐based shunt active filter for installation on a power distribution system. A main objective of the active filter is to achieve damping of harmonic propagation coming from series/parallel resonance between capacitors for power factor correction and line inductors in the distribution system. The active filter installed at the end terminal of a distribution feeder is controlled in such a way as to present infinite impedance to the external circuit for the fundamental frequency, and to exhibit low resistance for harmonic frequencies. As a result, the active filter acts as a damping resistor for the harmonic propagation, like a 50‐Ω terminator installed at the end of a signal transmission line. It is verified by experiment that the active filter intended for harmonic termination has the capability of harmonic damping throughout the distribution feeder. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 1–10, 2000     

A novel multi‐output high‐voltage‐isolated power supply system for semiconductor device series‐connected switches

This paper presents a novel scheme of a multi‐output power supply for solid‐state switches based on series‐connected semiconductor devices. By using the loosely transforming method, the system can realize high‐voltage isolation and a compact size, and its application range can be easily expanded to modular designed switch stacks for higher power ratings. The circuit structure and working principles are described. Based on the system operating equations, the design methodology is proposed and applied for parameter specification of a power supply system of two series‐connected switch stacks containing 20 outputs. Detailed calculations are given, and experimental results prove the feasibility of the proposed scheme. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

三相四线制变频电网的谐波及无功电流检测

为了满足变频电网提高电能质量的需要,提出一种基于通用瞬时无功理论和正序基波滤波器的谐波、无功及不平衡电流检测方法.针对基于传统通用瞬时无功理论的方法在电源电压畸变或不对称时检测不准确的问题,提出了改进算法.详细分析了正序基波滤波器的特性,采用带有自适应参数的正序基波滤波器提取正序基波电压,采用平均值法获得平均功率,同时应用到改进算法中,适应了电网基频的各种变化,克服了低通滤波器在变频工况下使用的缺陷.在飞机交流变频电网并联APF系统中对所提方法进行了仿真验证,并与Ip-Iq改进法和PHC法进行了对比.研究表明所提方法在电网基频处于不同稳态值或在稳态值间快速变化时均能实现准确,快速地检测.与传统方法相比,具有检测精度高,受变频环境影响小的优点.     

城市轨道交通供电系统谐波分布研究

针对城市轨道交通供电系统,对系统产生的谐波类型进行了分析,指出了谐波的危害性,分析了其特征,并详细分析了不同情况下注入系统节点的谐波大小的计算方法,特别是计算了35kV 系统和 110kV 系统在不同负荷状态下的特征次谐波的大小,并进行了实际的测量,建立系统谐波计算的分布图.对 110kV 侧的谐波电流进行了收集整理和研究,提出了降低谐波的方法和必要性.在此基础上,明确指出轨道交通供电系统应安装滤波装置或者有源滤波装置(APF),这不但可以大大地减小对电网的影响,也可以提高自身系统的运行质量和可靠性.     

Current waveform control of a high‐power‐factor rectifier circuit for harmonic suppression of voltage and current in a distribution system

This paper presents the input current waveform control of the rectifier circuit which realizes simultaneously the high input power factor and the harmonics suppression of the receiving‐end voltage and the source current under the distorted receiving‐end voltage. The proposed input current waveform includes the harmonic components which are in phase with the receiving‐end voltage harmonics. The control parameter in the proposed waveform is designed by examining the characteristics of both the harmonic suppression effect in the distribution system and the input power factor of the rectifier circuit. The effectiveness of the proposed current waveform has been confirmed experimentally. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(4): 62–71, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10046     

Suppression effects of active power filter on harmonics of distribution system including capacitors

Voltage distortion of 6.6-kV distribution systems has been increasing recently especially in commercial areas. Harmonic currents of certain orders are amplified and voltage distortions are generated by the resonance between system impedance and static capacitor under the leading power factor condition. This paper describes the results of a test on suppression effects on model systems and an actual system. The effect of the use of an active power filter on the resonant harmonics of the system including capacitor was verified.     

Deliverable‐power dependence on distribution‐line resistance and number of loads in low‐voltage DC distribution system

In this paper, we show that in a low‐voltage DC distribution system the deliverable power to a load has an upper limit P_lim due to the voltage instability at the receiving ends. On the basis of the previously derived concept of P_lim, we obtain the dependence of P_lim on the distribution line resistance R. In addition, we investigate the influence of the number of loads on P_lim. The result shows that a distribution line of lower R causes P_lim to be lower. This reduction in P_lim becomes more distinct for a larger number of loads. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Calculation of distribution system voltage and power flow state using measured values

This paper describes a techique of calculating voltage and power flow state of a distribution system using the information measured with two or more switches with sensors installed in a distribution system. In the proposed technique, a set of the power distribution section where two or more switches with a sensor are connected is defined as the large section, and the active power and reactive power consumption in the large section are calculated based on measurement information, voltage (RMS), current (RMS), and power factor. Using the simple distribution system model consisting of the large sections, the power consumption of the large section is calculated by the power flow calculation to separate power consumption and power distribution loss. It is distributed to the small sections that constitute the large section, and detailed power flow calculation is performed. Verification of the proposed technique and basic estimation of the calculation error were performed using the simple power distribution system model. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 164(4): 33–42, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20416     

Real‐valued MUSIC algorithm for power harmonics and interharmonics estimation

Recently, advanced spectrum estimation methods, including the MUSIC (Multiple Signal Classification) algorithms, are being gradually employed for high‐resolution power harmonics analysis. However, most of them are proposed to detect frequencies of complex‐valued signals, so that any real‐valued signal should be transformed into complex form. This data pre‐treatment may lead to additional computation burden. In addition, the picket‐fence effects also exist as in the FFT algorithm and cause poor frequency resolution. To overcome these drawbacks, a real‐valued MUSIC algorithm is proposed for power harmonics analysis in this paper. The algorithm is based on the subspace decomposition theory and the computation of pseudospectrum is also provided. Additionally, to improve the measuring precision, the Newton–Raphson algorithm is adopted to optimize the harmonic frequencies significantly. Simulation results show that, in the real‐valued MUSIC pseudospectrum, the spectral peaks of actual harmonic components can be more easily distinguished from the false peaks caused by noise, and the computational complexity is notably lower than that of the classic complex MUSIC, as well as the detecting accuracy is close to that of root‐MUSIC algorithm which is quite time consuming. Experimental results prove that the proposed strategy is more suitable for high‐resolution power harmonics estimation. Copyright © 2010 John Wiley & Sons, Ltd.     

电力系统谐波检测的FFT加窗插值算法与小波分析方法的比较

对电力系统谐波检测中常用的FFT加窗插值算法和小波分析算法进行了分析比较:FFT加窗插值算法具有检测精度高、实现简单、功能多且使用方便的优点,但计算量较大,因而实时性不够好;小波分析实时性好,能够获取较精确的基波信号,然而对于其他整数次谐波的幅值和相位则较难精确的获得,且难于构造分频严格、能量集中的小波,检测精度也有待改善.并通过仿真实验验证上述结论.     

Development of high voltage harmonic measuring instruments for distribution systems using optical voltage sensor and current sensor

Application of an optical measuring technique was attempted in order to develop harmonic voltage and current measuring instruments for distribution systems. To develop the harmonic voltage measuring system using a Bi₁₂GeO₂₀ crystal as a sensing Pockels cell for high‐voltage distribution lines, zinc oxide elements were adopted as a voltage divider. Also, an optical current sensor system was improved on the harmonic current measuring system using an R₃Fe₅O₁₂ film as a Faraday device. In practical three‐phase distribution systems, the developed high voltage harmonic measuring devices using the optical voltage sensor and current sensor were compared with conventional harmonic analyzers for low voltage. As a result, it was confirmed that the developed high voltage harmonic measuring devices had satisfactory characteristics for practical use. © 1999 Scripta Technica, Electr Eng Jpn, 128(4): 84–93, 1999     

未来型电力系统的广域测量和通信

简述灵活交流输电系统FACTS、新型直流输电系统和全可控电力系统是未来型电力系统新技术的主流；论述基于相量测量单元PMU的广域相量测量系统WAMS的基本功能，並分析了延迟和响应时间等因素对WAMS可用性的影响；指出基于先进光纤通信技术的新一代高速率、低延迟的全光纤通信网络特别适合电力系统的实时测量和控制。     

Effects of output power fluctuation on short‐circuit current of induction‐type wind power generators

Effects of the fluctuation inherent in wind speed are studied by a probabilistic method. The random variation in wind speed is responsible for random behavior in output power and internal voltage of a wind power generator. In case of fault occurrence at the instant of high internal voltage, the resultant short‐circuit current will be big, and vice versa. The DC component is also affected. According to the study, 2.4% and 1.3% increase of short‐circuit current in AC and DC components are observed respectively in a large variation case. This implies that the wind speed variation should be considered for accurate short‐circuit study. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(3): 27–36, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20721     

南南铝业供配电系统无功补偿的技术改造

供配电网合理的无功补偿,能够有效维持系统的电压水平,降低有功线损,减少电能的损耗。以提高南南铝业供配电网功率因数、降低电能损耗为目的,提出了切合公司实际的一种无功补偿方式,即在各分厂的10kV变压器低压侧加装无功补偿设备,实行自动补偿,并在公司挤压厂进行了试点实施,取得了较好的节电效果。     

有源电力滤波器在分布式发电系统中的应用

提出了利用现有的设备(软启动逆变器)来抑制分布式发电系统中微型燃气轮发电机谐波电流的方法,并详细给出其拓扑结构,谐波电流检测方法及滞环控制策略。仿真结果表明:所设计的拓扑结构和采用的控制方法是可行的,完全消除了5次和7次谐波电流。     

分布式电源接入的配电系统多类型无功源出力优化方法

同时考虑光伏发电系统、风电机组、静止无功发生器、并联电容器等多类型无功源的协同运行问题,建立多类型无功源协同运行的优化模型,增强了无功协调能力和优化效果。研究了光伏逆变器无功的调节原理和双馈电机风力发电系统无功调节能力。考虑光伏发电系统和风电机组的无功特性,构建向分布式电源和静止无功发生器的输出或吸收无功功率的约束条件函数。采用潮流雅可比矩阵直接变换求取灵敏度系数,构建基于线性规划的分布式电源、并联电容器和静止无功发生器输出无功功率的约束域及其罚函数。通过潮流雅可比矩阵进行矩阵变换,构建考虑有功网损最小化的目标函数灵敏度系数的线性化模型。采用两阶段单纯形法对优化问题进行求解,获得了好的效果。     

Experimental evaluation of active power factor correction techniques in a single-phase AC-DC boost converter

The increasing need to improve power quality with the reduction of the harmonic content of current and voltage waveforms has been intensively analyzed in several studies, thus motivating the proposal of many high power factor rectifiers based on the classic converters such as boost and buck-boost. Moreover, distinct control techniques have also been proposed due to the commercial availability of integrated circuits (ICs) dedicated to impose sinusoidal input currents in switch-mode power supplies (SMPSs). The boost converter operating in continuous conduction mode (CCM) is by far the most traditional choice for this purpose due to circuit simplicity and low electromagnetic interference (EMI) levels. Within this context, this work analyzes some of the most important control techniques used in power factor correction (PFC). The performance of a single-phase boost converter using peak current mode control (PCMC), average current mode control (ACMC), and one cycle control (OCC) is evaluated experimentally in detail. A comprehensive analysis of key aspects such as the input current waveform and respective harmonic content, dc output voltage, and dynamic response of the converter is also presented.