电气设计外文翻译

英文原文

Quality Control Testing Of New Technologies To Analyse Energy

Electric quality control testing of new technology analysis summary : With advances in technology, modern power system electricity load structure has undergone major changes, such as the semiconductor rectifier, transistor rubber and frequency conversion adjustment devices, steel-making furnaces, electric railways and household appliances such as load rapid development, because of its nonlinear, and the uneven impact of the electricity identity the grid voltage waveform distortions occur as a flash change and the three-phase voltage fluctuations and imbalances, or even cause system frequency fluctuations, the quality of electricity supply to cause serious interference or "pollution" . In the face of increasing electricity grid CKS quality issues, which makes electric quality research is extremely pressing. Electric quality testing is the most direct access to relevant data conversion means, but also the quality of other follow-up High energy applied research front.

Keyword : electric quality testing neural network

1 electric quality research, the application of new technologies background

With advances in technology, modern power system electricity load structure has undergone major changes, such as the semiconductor rectifier, transistor rubber and frequency conversion adjustment devices, steel-making furnaces, and household appliances, such as railway electrification load rapid development, because of its nonlinear, and the uneven impact of the electricity identity the grid voltage waveform distortions occur as a flash change and the three-phase voltage fluctuations and imbalances, or even cause system frequency fluctuations, the quality of electricity supply to cause serious interference or "pollution" . In the face of increasing electricity grid CKS quality issues, which makes electric quality research is extremely pressing.

On the other hand, the quality of electricity supply is gradually enterprises and electricity consumers are of common concern. Since the 1990s into the 20th century, as the semiconductor, computer technology is developing rapidly, the number of high-tech enterprises have emerged, a large number of computer control devices and production lines. Quality of electricity put new demands; And the development of the electricity market to greater awareness of the power supply enterprises : users need is their own needs. Against this background, the result of poor quality due to electricity users of defective equipment or parking situation. Quality standards should be seen as electricity. Of course, there are many bad quality of electricity users to transfer quality sensitivity also varied. One boat, the electric power supply enterprises of different quality may be a hierarchy, respectively pricing, users can freely choose. But also because of our failure to achieve quality grain at the present. Therefore, further work is required to improve the quality of electricity users in the adjacent settlement. With the quality of electricity equipment sensitivity to changes in electricity, further expand the scope of quality electricity. demanding more detailed classification. In the new electricity market environment, the quality of electrical energy has become a power consumption characteristics of such commodities, largely reflects the quality of electricity service. Therefore, relevant departments are increasing the quality of electrical energy regulation and governance.

These background, the quality of electrical energy research urgent need to promote new technologies through the application of these new technologies so that the quality of electrical energy from the testing,

analysis and monitoring aspects have been improved, thus enabling discovery and rules, and improve the quality and supply of services.

2.power quality testing new technologies

Electric quality testing is the most direct access to relevant data conversion means, but also the quality of other follow-up High energy applied research front.

2.1 quality testing of electric current

To monitor the quality of electrical energy to electrical energy is the quality of information of direct channels, while the instrumentation has many, but most only continuity and stability testing indicators, and traditional theories based on valid value testing technology because of the time window is too long, only valid value can not measure accurately describe the actual electricity quality, Thus the need to develop new detection technologies to meet the following requirements : First, to capture rapid (ms level even ns level) instantaneous interference waveform. It is difficult because many disturbances in an individual parameter (such as valid value) to complete description, and random nature of the strong, and therefore the need for multiple tests to initiate volume and devices, such as the worth and waveform distortions, worth rising rates. Second, the need to measure the worth of harmonics and inter-harmonics, phase, the need for adequate high sampling rate, so that they can detect the high harmonics information. Third, the establishment of an effective analysis and automatic identification systems to enable them to reflect the characteristics and electric quality indicators over time changes. With the electricity market and electricity quality of legislation, the quality of power supply will cause increasingly wide attention developed into electrical energy quality monitoring distribution of the new SCADA system is energy management system new directions of research. This area will be difficult for current and voltage measurements at the same time continuing to identify the classification of quality indicators and statistics, large amounts of data, hence the need to develop a strong database for effective management.

2.2 New technology applications

At present, electric quality in hardware and software, digital signal processing applied mainly (DSP), and new technologies such as virtual machines Xiaobo change as new algorithms. introduced to the basic concepts of the energy and quality measurement, and given the number of measurements for change detection analysis methods and flash simulation waveform. DSP devices discussed in compensation by the power quality testing applications, the device used to highlight the achievement of physical hardware and software to control the actual development. quality testing for the electric system under the real-time nature of complex algorithms and support the special request CPU based on the plug-in a real-time system solutions. Focused on the hardware system design and equipment based on CPU system software design ideas. After debugging, and operation of the actual design, circuit normal function, demonstrated the reasonableness of the design and usability. Compared to the previous design, the real-time nature of the good, small size and low cost advantages. based on a strange sexual Xiaobo change signal detection theory and in the quality Zantai electric signal detection of a detailed study applications through based on the standard deviation estimated Xiaobo wave passed algorithms, the effective exclusion of noise interference and the failure to achieve the precise moment positioning. under Xiaobo change theory, data quality testing in conjunction with electrical characteristics, and will be based on their coefficient Xiaobo threshold power quality testing methods for data compression. Simulation calculations and analysis indicates that the approach is simple and better compression results to retain local identity compressed signals, the calculation speed, Very suitable for real-time demands strong occasions. quality testing of electrical

components and operating principles of the system conducted a detailed briefing. Energy Quality Assessment System software applications MATLAB and C++ mixed programming language technologies. The system not only to achieve precise sampling data grid, the electricity grid can also analyse quality indicators, and visual graphics to show. [10] introduced virtual machines electric quality testing and analysis system formed on LabVIEW software to achieve frequency tracking technology, and introduced the use of electric network quality long-range detection and data analysis methods, and finally give some of the procedures.

3 qualitative analysis of the new energy technology

Electric quality analysis of the various sources of interference and calculate the mathematical description of the electricity system, and to develop corresponding software and engineering approach to the analysis of electrical systems for the analysis of quality problems, providing guidance to improve the quality of electricity. The sources of interference are different in nature, interference spectrum GHz from 0Hz to the broad context of grid components in different interference of a different role in the performance, interference sources and the establishment of grid components (or partial grid) accurate mathematical models are sometimes difficult to calculate and analyse the accuracy depends not only on mathematical models and calculation also depends on the credibility of the information grid basis. In recent years, various analytical methods based on digital technology in the energy field quality application :

First analysis of the distribution network in harmonics

Second, the analysis arising from the various sources of disturbances and waveform distortions in the network transmission.

Third, analysis of quality control devices in addressing energy issues related to the role;

Forth，more coordination and control devices and other controls integrated control and other issues.

There are three methods currently used :

(1) 24-hour simulation methods qualitative analysis of the ways in which electricity most widely used, its main purpose is to use the power of 24-hour simulation procedures to the various quality studies Zantai phenomenon. 24-hour simulation is relatively common procedure mainly EMW, EMTEC, NETOMAC, BPA systems Zantai procedures and spice simulation, PSPICE, MATLAB, Saber, power electronic simulation procedures in two broad categories. These simulation procedures in constant development, its function has become increasingly strong, and can also use their electrical equipment, components of the power system harmonics analysis and modelling.

(2) frequency domain analysis of the methodology of the analysis of the major issues for the harmonics, including frequency scanning, harmonics trend calculation. Taking into account the number of nonlinear dynamic load characteristics, and in recent years has also filed a mixed trend resolved calculation that, in conventional harmonics trend calculation basis, using EMTP, 24-hour simulation of nonlinear load procedures for simulating the calculation may derive the dynamics of the harmonics lost volume, thus resolved by dynamic trend Xie.

(3) Based on the method used here mainly referring to Fourier transformation methods, short Fourier transformation methods and change Xiaobo (wavelet). As a classical signal analysis methods are orthogonal Fourier transformation, the complete, and many other advantages, but also such as FFT fast Fourier algorithms, and therefore the quality of analysis in the field of energy widely applied. But in the

Portuguese use, the following conditions must be met : First, to meet the requirements of sampling theorem, sampling frequency must be more than twice the highest frequency signal; Second, the analysis of the waveform to be produced, the cycle of change over time. Therefore; When the sampling frequency or signal does not meet the above conditions, using FFT analysis would bring the error analysis. In addition, the FFT transformation of the whole time of scoring, time information to be underutilized; Any mutations signals, the spectrum will be scattered throughout the necktie. To resolve these issues, using the window Gabor made fast Fourier transformation method is not a steady process as a series of short between the assembly process will not be smooth for the Fourier transformation signal analysis. As the actual process of multi-criteria analysis requirements-friendly window from the adaptability of the HF frequency window, large, small, window; Low frequency, the frequency of small windows, large windows, and StFt time-frequency window is fixed. Therefore, it is appropriate to the scale analysis of the same process, not suitable for multi-scale analysis of the process and mutation process. But this method is not separated form orthogonal started elusive efficient algorithms. Xiaobo has changed since the time-frequency localized characteristics and StFt etc. overcome these shortcomings, and are particularly suited to mutations signal and not a signal analysis. Xiaobo changing as a new digital technology was the introduction of engineering, has been in image processing, data compression and signal analysis, and other areas to be widely applied. As soon fade Xiaobo function itself, but also a kind of Zantai waveform will be used in the field of electricity qualitative analysis, particularly Zantai areas will be FFT analysis process, the StFt incomparable advantages. Recently, the literature on the application of existing methods of energy conversion Xiaobo quality assessment, electromagnetic Zantai waveform analysis and modelling of electric power system disturbances quality research.

4 electric quality of the artificial intelligence research of new technologies

In recent years, an expert system, neural networks, fuzzy logic and artificial intelligence representative of the evolution of new technologies for more comprehensive application of energy has begun to qualitative research because it is a more complex workload and the large volume of data processing systems. Particularly in the electricity qualitative analysis, many artificial intelligence applications to support analysis of complex issues. And a prominent feature of these new technologies is very broad cross-application, sometimes it is difficult to say what kind of technology, but mainly to some other squads. Said it usually mixed technologies.

4.1 expert system

despite the higher costs and expert systems in the development process take too long, but there is still a lot of applications [11-22]. These primarily reflected in the voltage and waveform distortions in the classification; Expert analysis using harmonics; Quality solutions to the energy in the framework of expert systems development; Measurement and analysis of electric power systems and the quality of electromagnetic compatibility; Identification of a power quality event can be expanded through the system; Energy management quality data quality of professional training electricity advisory personnel.

4.2 neural network

Artificial neural networks as a more mature intelligence technology, the quality of electrical energy has been in the wider applications, they mainly contains [23-37] : from the quality of information, identification of non-electric energy quality events; To have resolved the model modelling; In the grid, estimates and the evaluation resolved distortions and other electrical quality; Xiaobo neural network integration to distinguish and identify energy conversion quality incidents; in the need to avoid noise and

harmonics son of harmonics analysis; Electricity engineers for the development of a quality problem solving energy aids;

4.3 fuzzy logic

Fuzzy logic and neural network learning with the fuzzy logic is the most popular artificial intelligence technology. In the quality of their energy has also made many new research progress : diagnostic quality of electricity; Electric utility to provide the quality of staff supporting tools; Data quality and data management power excavation to acquire relevant knowledge; development of the electricity sector and users of energy quality professional training system; to raise the quality of electric interference classification; adaptive collection of energy side has roots voltage and current; Research at the appropriate time to contact condenser for the vote is resolved to control the level of distortions; in a vague assessment by the establishment of quality indicators used electric control programmes based on fuzzy logic to develop a unified electricity quality management device; forecasting and the identification of the non-functioning system; To ensure the quality of power supply voltage based on fuzzy logic implementation without merit compensation.

5 electric quality control, new technologies

In the quality control of electrical energy, I think there are two trends : One is the section mentioned intelligent, intelligent aimed at alleviating human labor, the quality of electrical energy to the issue of automatic identification and data processing, thereby achieving a comprehensive unmanned surveillance functions.

Another is long-range. With the development of the power industry and grid-scale expansion of the electricity sector and users of the urgent need for more extensive monitoring points to monitor, but the point spread, distance different monitor quality issues on the basis of electricity users and network needs are different. So long-range can be adapted to different levels of control, so that quality control points to the distribution of electricity to the grid anywhere, and have good online functions.

But the inevitable result of the long-range problem is to monitor and control station point communications between data quality and large electric transmission issues are very important. [50] power line carrier-based to achieve a more simple RMON. Computer network technology, the quality of electric power supply system for different locations on the long-range monitoring and analysis provided effective means. discussed energy supply system based on the quality of Internet monitoring and analysis systems, including the use of GPS technology, delegated more synchronous sampling, using Windows Server and Jan networking platforms, the use of SQL Server database management supply network operation data multiple use of the electric power supply systems analysis software for quality simulation analysis, and proposed management measures. The system will provide for the safe operation of the electricity system security. introduced a hub to 220kv transformer stations for continuous monitoring of the actual use. The results showed that the use of PM30 in transformer stations recording devices can achieve continuous real-time monitoring of the quality of electricity, recording, storage and overturn, the electricity network and the quality and technical supervision of automation possible. However, the current long-range quality control of energy use is not too mature. Whether in remote online request form a complete and comprehensive system of monitoring large function needs to be further research and development. In addition, the network of the electricity used by quality control systems used in communications with the programme structure is different, and who better who is bad, not yet associated comparison.

中文翻译

电能质量检测分析监控

随着科技的进步，现代电力系统中用电负荷结构发生了重大变化，诸如半导体整流器、晶闸管调压及变频调整装置、炼钢电弧炉、电气化铁路和家用电器等负荷迅速发展，由于其非线性、冲击性以及不平衡的用电特性，使电网的电压波形发生畸变成引起电压波动和闪变以及三相不平衡，甚至引起系统频率波动等，对供电电能质量造成严重的干扰或"污染"。电网中正面对越来越多的电能质量问题，这使得电能质量的研究十分紧迫。电能质量检测是获得电能相关数据的最直接手段，也是电能质量其他后续高级应用研究的前端。

1 电能质量研究中新技术的应用背景

随着科技的进步，现代电力系统中用电负荷结构发生了重大变化，诸如半导体整流器、晶闸管调压及变频调整装置、炼钢电弧炉、电气化铁路和家用电器等负荷迅速发展，由于其非线性、冲击性以及不平衡的用电特性，使电网的电压波形发生畸变成引起电压波动和闪变以及三相不平衡，甚至引起系统频率波动等，对供电电能质量造成严重的干扰或"污染"。电网中正面对越来越多的电能质量问题，这使得电能质量的研究十分紧迫。

另一方面，电能质量正逐步受到供电企业和电力用户的共同关注。进入20世纪90年代以来、随着半导体、计算机技术的迅速发展，一批高新技术企业应运而生，出现大量的微机控制装置和生产线.对电能质量提出了新的要求；而电力市场的发展，使供电企业进一步认识到：用户的需要也是自身的需要。在这样的背景下，因电能质量不良而使用户设备停机或出次品的情况.仍应看作电能质量不合格。当然，电能质量不良有多种情况，用户对电能质量的敏感程度也各不相同。一船来说，供电企业可对不同的电能质量划分等级、分别定价、用户可以自由选择。但由于我国目前还未能实现优质优价。因此，进一步改善电能质量的工作基本上要求在用户侧解决。随着各种用电设备对电能质量敏感度的变化，电能质量的范围进一步扩大.分类更细要求更高。在新的电力市场环境下，电能质量已成为电能这种商品的消费特性，很大程度上体现了供电部门服务品质。所以有关部门正在加大对电能质量的监管和治理。

这些背景下，电能质量的研究迫切需要一些新技术来推动，通过这些新技术的应用，从而使电能质量从检测、分析和监控等方面得到提高，从而有利发现问题和规律、改善供电质量和服务。

2 电能质量检测中的新技术

电能质量检测是获得电能相关数据的最直接手段，也是电能质量其他后续高级应用研究的前端。

2.1 当前电能质量检测的情况

电能质量进行监测是获得电能质量信息的直接途径，虽然这方面的检测仪器已不少，但大多数只局限于持续性和稳定性指标的检测，而传统的基于有效值理论的检测技术由于时间窗太长，仅测有效值已不能精确描述实际的电能质量问题，因此需发展满足以下要求的新检测技术：①能捕捉快速(ms级甚至ns级)瞬时干扰的波形。因为许多瞬间扰动很难用个别参量(如有效值)来完整描述，同时随机性强，因此需要采用多种判据来启动量和装置，如幅值、波形畸变、幅值上升率等。②需要测量各次谐波以及间谐波的幅值、相位，需要有足够高的采样速率，以便能测得相当高次谐波的

信息。③建立有效的分析和自动辨识系统，使之能反映各种电能质量指标的特征及其随时间的变化规律。

随着电力的市场化和电能质量的法规化，供电质量将引起越来越广泛的重视，开发出考虑电能质量监测的新的SCADA系统是配电能量管理系统的新研究方向。这一领域的难点将是对电流、电压的同时持续测量，对质量指标的分类辨识和统计，数据量大，因此需要开发强大的数据库来进行有效管理。

2.2 新技术应用

当前，电能质量在硬件和软件上应用了主要有数字信号处理（DSP），虚拟仪器等新技术以及新的如小波变换的算法。介绍了有关电能质量的基本概念和衡量标准，并给出了适合数字测量的分析方法和闪变检测仿真波形。讨论了DSP器件在电能质量补偿器中的检测应用，重点介绍用该器件实现物理硬件和控制软件方面的实际开发。根据电能质量检测对于系统实时性和支持复杂算法的特殊要求，提出一种基于双CPU的嵌入式实时系统解决方案。主要讨论设备的硬件系统设计和基于双CPU 系统的软件设计思想。设计经过实际的调试和运行，电路功能正常，证明了该设计的合理性和可用性。相对于以往的设计，具有实时性好、体积小和成本低的优点。对基于连续小波变换的信号奇异性检测原理及其在电能质量暂态信号检测中的应用进行了详细的研究，通过基于标准偏差估计的小波消噪算法，有效排除了噪声干扰，实现了精确的故障时刻定位。根据小波变换的理论,结合电能质量检测数据的特点,文中将基于小波变换系数的门限方法应用于电能质量检测数据的压缩。仿真计算结果及其分析表明,该方法简单而且压缩效果较好,能保留压缩信号的局部特征,计算速度快,很适合于实时性要求较强的场合。对电能质量检测系统的组成部分和工作原理进行了详细介绍。电能质量检测系统的软件应用MATLAB与C++语言的混合编程技术进行开发。该系统不但能实现电网数据的精确采样,还可以分析电网的各项电能质量指标,并以直观的图形显示出来。介绍了虚拟仪器的电能质量检测和分析系统的组成,介绍LabVIEW软件实现的频率跟踪技术,并介绍了使用网络对电能质量进行远程检测和数据分析的方法,最后给出了部分程序。

3 电能质量分析中的新技术

电能质量的分析计算涉及对各种干扰源和电力系统的数学描述，需要开发相应的分析软件和工程方法来对各种电能质量问题进行系统的分析，为改善电能质量提供指导。由于干扰源性质各异，干扰的频谱从0Hz到GHz的广宽范围内，电网元件在不同干扰作用下呈现不同的性能，因此建立干扰源和电网元件(或局部电网)准确的数学模型有时困难很大，而分析计算的准确性不仅取决于数学模型和计算方法，还有赖于电网基础资料的可信度。近年来，基于数字技术的各种分析方法已在以下电能质量领域中得到应用：

①分析谐波在网络中的分布

②分析各种扰动源引起的波形畸变及在网络中的传播

③分析各种电能质量控制装置在解决相关问题方面的作用；

④多个控制装置的协调以及与其他控制器的综合控制等问题。

目前所采用的方法有三种：

(1) 时域仿真方法该方法在电能质量分析中的应用最为广泛，其主要的用途是利用各种时域仿真程序对电能质量问题中的各种暂态现象进行研究。目前较通用的时域仿真程序主要有EMW、EMTEC、NETOMAC、BPA等系统暂态仿真程序和SPICE、PSPICE、MATLAB、SABER等电力电子仿真程序两大类。由于这些仿真程序在不断发展中，其功能日益强大，还可利用它们进行电力设备、元件的建模和电力系统的谐波分析。

(2) 频域分析方法该方法主要用于谐波问题的分析计算，包括频率扫描，谐波潮流计算等。考虑到一些非线性负载的动态特性，近年来又提出一种混合谐波潮流的计算方法，即在常规的谐波潮流计算法基础上，利用EMTP等时域仿真程序对非线性负载进行仿真计算，可求出各次谐波动态电流失量，从而得到动态谐波潮流解。

(3) 基于变换的方法这里主要指Fourier变换方法、短时Fourier变换方法和小波变换(wavelet)方法。作为经典的信号分析方法Fourier变换具有正交、完备等许多优点，而且有象FFT这样的快速Fourier算法，因此已在电能质量分析领域中得到广泛应用。但在运用FR时，必须满足以下条件：①满足采样定理的要求，即采样频率必须是最高信号频率的两倍以上；②被分析的波形必须是稳态的、随时间周期变化的。因此；当采样频率或信号不能满足上列条件时，利用FFT分析会给分析带来误差。此外，由于FFT变换是对整个时间段的积分，时间信息得不到充分利用；信号的任何突变，其频谱将散布于整个领带。为解决上述问题，Gabor利用加窗，提出了短时Fourier变换方法，即将不平稳过程看成是一系列短时乎稳过程的集合，将Fourier变换用于不平稳信号的分析。由于实际多尺度过程的分析要求时-佰窗口具有自适应性，即高频时频窗大、时窗小；低频时频窗小，时窗大，而STFT的时-频窗口则固定不变。因此，它只适合于分析特征尺度大致相同的过程，不适合分析多尺度过程和突变过程。而且这种方法的离散形式没有正交展开，难以实现高效算法。小波变换由于具有时-频局部化的特点，克服了以上FFT和STFT的缺点，特别适合于突变信号和不平稳信号的分析。小波变换作为一种新的数字技术被引入工程界后，已在图像处理、数据压缩和信号分析等领域得到广泛应用。由于小波函数本身衰减很快，也属一种暂态波形，将其用于电能质量分析领域，尤其是暂态过程分析领域将具有FFT、STFT所无法比拟的优点。最近，已有文献介绍应用小波变换方法进行电能质量评估、电磁暂态波形分析和电力系统扰动建模等电能质量问题的研究。

4 电能质量研究中的人工智能新技术

最近几年，以专家系统, 神经网，模糊逻辑和进化计算为代表的人工智能新技术已开始较全面地应用于电能质量研究，因为它是个较复杂，工作量和数据处理量很大的系统工作。特别是在电能质量分析方面, 很多人工智能应用来进行辅助分析，对复杂的问题进行处理。而且这些新技术的一个突出特点就是交叉应用的非常广泛，有时很难断言就是哪种技术，而是以某种为主，其它为辅的。也就通常所说的混杂技术。

4.1 专家系统

尽管专家系统成本较高且在开发过程中耗时过长，但依然出现了很多应用。这些主要体现在，对畸变的电压和波形进行分类；利用专家系统分析谐波；对电能质量问题的解决方案在专家系统架构下进行开发；测量和分析电能质量及电力系统电磁兼容性；识别电能质量的事件通过一个可扩展的系统；管理电能质量数据，培训电能质量问题的专业咨询人员。

4.2 神经网络

人工神经网作为较成熟的智能技术，在电能质量中已有较广泛的应用，它们主要包含: 从非电能质量信息中识别电能质量事件；对谐波的产生模式进行建模；在电网中估计和评价谐波畸变和其它电能质量问题；以神经网整合小波变换分辨和识别电能质量事件；在需要避免噪声和子谐波时对谐波进行分析；

为电力工程师们解决电能质量问题开发一个辅助工具；

4.3 模糊逻辑

模糊逻辑和带神经网学习能力的模糊逻辑是当前最流行人工智能技术。它们在电能质量研究方面也取得了不少新进展：诊断各种电能质量问题；对电能质量工作人员提供实用性的辅助工具；管理电

能质量数据并进行数据挖掘以获得相关知识；开发对供电部门人员和用户进行电能质量问题专业培训的系统；对引起电能质量问题的各种干扰进行分类；适应性的采集电能量，方均根电压和电流；研究在适当的时候对串联电容器进行投切来控制谐波的畸变水平；在模糊约束下建立评价电能质量的指标利用基于模糊逻辑的控制方案开发一个统一的电能质量管理器；预测和识别系统的非正常运行情况；为保证供电电压质量实施基于模糊逻辑的无功补偿。

5 电能质量监控中的新技术

在电能质量监控方面，我认为有两个趋势：其中之一就是上节中提及的智能化，智能化旨在减轻人的劳动，能自动对电能质量问题进行识别和数据处理，从而实现全面的无人监控功能。另一个则是远程化。随着电力工业的发展和电网规模的扩大，供电部门和用户都迫切需要对较大量的监测点进行监控，然而各点的分散，距离远近不同，监测电能质量的问题也根据用户和电网的需要而各不相同。所以远程化就可以适应不同层次的监控要求，从而使电能质量的监控点能够分布到电网中的任何地方,并且具有良好的在线功能。

但远程化必然带来的问题就是，监测点和监控站之间的通信问题以及大量的电能质量数据的传输问

题都十分重要。以电力线载波通讯为基础实现了较为简单的远程监控。计算机网络技术的发展 ,

为不同地点供电系统电能质量的远程集中监测和分析提供了有效的手段。论述了基于 Internet的

供电系统电能质量的监测与分析系统 ,主要包括利用 GPS授时技术进行多点同步采样 ,利用

Windows NT2 0 0 0和 IIS建立网络平台 ,利用 SQL Server数据库管理供电网络运行数据 ,使用

多种分析软件对供电系统的电能质量进行仿真分析 ,并提出治理措施。该系统可为供电系统的安全

运行提供保障。介绍某地２２０kv枢纽变电站进行连续监测的实际使用情况。结果表明，在变电

站中使用ＰＭ３０记录仪，可连续实时地实现电能质量的监测、记录、存储和远传，使电能质量技

术监督实现网络化和自动化成为可能。然而, 目前电能质量监控远程化的成熟应用还不太多。能否

在远程在线的要求形成完整的大系统和全面的监控功能，还有待进一步研究和开发。此外，网化的

电能质量监控所用的系统结构必然会随着所采用通信方案而不同，谁优谁劣，尚未能进行相关的比

较。

2. The Advancement of Adaptive Relaying in Power Systems Protection

2.1 Abstract

The electrical distribution system in the United States is considered one of the most complicated machines in existence. Electrical phenomena in such a complex system can inflict serious self-harm. This requires damage prevention from protection schemes. Until recently, there was a safe gap between capacity to deliver power and the demand. Therefore, these protection schemes focused on dependability allowing the disconnection of lines, transformers, or other devices with the purpose of isolating the faulted element. On some occasions, the disconnections made were not necessary. The other extreme of reliability calls for security. This aspect of reliability calls for the operation of the protective devices only for faults within the intended area of protection. There is a tradeoff here; where a dependable protection scheme will assuredly prevent damage, it is prone to unnecessary operation which can lead to cascading outages.

Where a secure scheme will not operate unnecessarily, it is prone to pieces of the system becoming damaged when relays fail to operate properly. With microprocessor based relaying schemes, a hybrid reliability focus is attainable through adaptive relaying. Adaptive relaying describes protection schemes that adjust settings and/or logic of operations based on the prevailing conditions of the system. These adjustments can help to avoid relay miss-operation.

Adjustments could include, but are not limited to, the logging of data for post-mortem analysis, communication throughout the system, as well changing relay parameters. Several concepts will be discussed, one of which will be implemented to prove the value of the new tools available.

2.2 Power Systems History

The distribution of electricity in the United States of America can be traced back to September 4th, 1882, when Thomas Edison opened the Pearl Street Station in lower Manhattan.

Serving about a quarter of a square mile, this direct current (DC) system was primarily used for lighting in the financial district of New York. Edison showed that it was possible to efficiently provide electricity from a central generating station. The issue with DC systems was that the end consumer had to be located within a few miles of the generating station. The problem was that the low voltage used with this type of distribution led to higher currents and higher losses on the lines used to distribute the electricity. This forced the generating plants to be small which reduced efficiency, and it meant that only small distribution systems in densely populated areas would be effective [1].

In distribution systems the voltage is held constant and the current flowing through the lines depends on the load being served. The losses associated with the lines used to distribute the electricity vary with the square of the current running through the lines. So if the current through the lines doubles, the losses associated with the lines actually quadruples. At the time Edison started implementing his systems, there was no way to easily change the voltage in a DC system.

The ability to vary the voltage of the distribution lines would allow for the reduction of current during transmission, which was being developed within alternating current (AC) systems. AC allowed for transformers to increase the voltage required by transmission and a reduction to a voltage level that is safe for end consumers to use; this significantly reduces the losses of sending electricity over longer distances. Nikola Tesla was the pioneer of this AC technology as well as the concept of polyphase distribution [1].

These competing strategies of electrical distribution, AC and DC systems, led to what is commonly known as the Battle of the Currents. Thomas Edison, owning the patents for DC systems, argued that AC and the higher voltages associated with it was unsafe. At the same time, however, George Westinghouse was building AC transmission li nes that stretched for miles. This, along with Nikola Tesla’s development of an AC motor among other developments, led to the ultimate victory of AC systems. This victory of alternating current led to the electrical distribution system we have today in which large generating stations delivering power over long distances at high voltages, which is both economical and efficient in comparison to the original DC systems [4]. This did, however, lead to several engineering issues to which solutions are still being developed today.

The AC system pioneered by Westinghouse and Tesla has developed into one of the most complex machines in the world. The growth started with many small independent systems. For reliability purposes, these systems were interconnected. This interconnection of many small systems meant that the number of machines necessary for reserve operation during peak loads was lowered. The interconnection also enabled utility companies to get the cheapest possible power from their neighbors. These interconnections grew into the massive system which we have today. There are issues that arose with the creation of this massive system; these issues include higher fault currents, cascading failures in which multiple smaller systems are affected when the problem only occurred in one of them, and a very delicate balancing act that occurs between systems. The planning that goes into this system, especially the protection of the system itself, is very complicated [5]. This system is generally broken down into generation, transmission, and loads. The

transmission portion is divided into transmission, subtransmission, and distribution; each having different voltage levels controlled using transformers.

2.3 Generator

Generators are used to convert different forms of energy into electrical energy. Most generators in use today convert mechanical energy into electrical energy using magnetic field interactions. This mechanical energy is generally provided in the form of a spinning prime mover. The prime mover usually has a magnetic field associated with it, and its spins within the stator coils; the stator is the stationary portion of a generator, and the field on the rotor induces currents within those stator coils. The spinning action can be provided using a steam turbine where some source of heat boils water to drive that turbine, or in the case of a hydroelectric dam, water could spin a turbine directly. Sometimes internal combustion engines can also be directly coupled to a prime mover. Steam power plants generate their heat by burning coal, natural gas, or oil as well as using nuclear reactions to generate heat. In the case of using a prime mover type generator, the speed at which that generator spins is extremely important because it determines the electrical output frequency. The great thing about all the types of generation discussed so far is that their output levels can be controlled by varying the amount of energy put into the prime movers.

Other, less controllable, forms of generation include renewables like solar and wind power. Solar power can be in the form of photovoltaic energy which needs to be converted from DC to AC to contribute to the system, or solar thermal which can be incorporated like any other thermal based generation. Wind power generates electricity with a prime mover, but because wind speeds are not constant the electricity must be conditioned using power electronics to ensure the output has the correct voltage and frequency. The main issue with these types of generation is that there is no way to control their output, so there isn’t any way to predict accurately how these sources will contribute. Another issue is that when small scale projects are implemented and feed energy back into the grid, current flow can change direction which may affect the operation of certain types of protective relays. So while it is good to have a contribution from renewable resources, there is a tradeoff in the predictability of operation.

2.4 Transformers

Transformers are an essential part of the electrical distribution system, as discussed earlier. Generation is generally done at voltage levels between 13.8 kV and 24 kV. Consumption of this electricity is generally done at voltage levels between 110 V in homes and up to 4160 V in large industrial plants. Transmission of

electricity can occur at levels of 115 kV to 765 kV in the United States, and go as high as 1 megavolt in other parts of the world. Transformers are what make this wide range of voltage level capabilities possible. Without transformers and the ability to vary voltage levels, it would be much less efficient to transmit power over great distances.

Transformers operate based on Faraday’s law of induction. Faraday’s law states that if magnetic flux passes through a coiled conductor it will induce a voltage in that conductor that is directly proportional to the derivative of that flux and the number of turns in the conductor coil. In a transformer, a flux is induced by a primary coil that is wrapped around a ferromagnetic core. The ferromagnetic core is used to give a path to the flux that has a high permeability. There is then a secondary coil which is wrapped around the same ferromagnetic core which has a voltage induced on it by the flux traveling through the core. The amount of flux is dependent upon the voltage and number of turns on the primary coil, and the voltage on the secondary coil is determined by the flux and the number of turns in the coil. Because the number of turns directly determines the ratio of the primary voltage to the secondary voltage, this ratio is commonly referred to as the turns ratio.

In an ideal world, a transformer would take a voltage from one level to another without any type of losses, but this isn’t the case. Transformer losses include copper losses, eddy current losses, hy steresis losses, and leakage flux. Copper losses are due to the resistance associated with the coil of wire itself and are proportional to the square of the current flowing through the coils of the transformer. Eddy currents are losses from unwanted currents induced on the core of the transformer and are proportional to the square of the voltage across the terminals of the transformer. Hysteresis losses are due to the rearrangement of magnetic domains in the core and are a function of the voltage applied to the transformer. Copper, eddy current, and hysteresis losses are all consumers of real power and are modeled as resistances. Leakage flux is simply flux that is not captured by the core and is passed to the other coil in the transformer. It is a function of the current flowing through the coils. Leakage fluxes are consumers of reactive power and are modeled as inductive impedances. These losses, however, are small in comparison to the losses that would occur in transmission if transformers were not available.

2.5 Adaptive Protection Schemes

Adaptive protection schemes are the result of the application of microprocessors in the area of protective relays and are growing in importance in the electrical power systems in the United States and

worldwide. These schemes may have complicated implementations as far as programming, but their concepts can be explained fairly easily. Many of these concepts are simply expansions on previous protection applications. Several of these concepts will be explored, including previous system events that could have been mediated with the help of these new concepts.

2.6 Differential Protection

Differential protection schemes are set up simply to check for any difference between two quantities at a given instance. Limitations on time synchronization made this implementation only reasonable for equipment protection and difficult for other applications until the recent advent of GPS signals. On the other hand, for signals collected from distant points into a system, the burden of communication made the implementation of differential protection difficult or unattainable. While this type of protection could be useful in detecting a difference in current from one substation to the next, historically its application required the two measurements to be taken very close to one another because of the constraints on communication. So the scheme was limited generally to transformer and generator protection. Before microprocessor-based systems and IEDs the nature of these two types of protection were limited by several issues, specifically mismatches in current transducers.

Percentage differential protection of transformers finds the difference between two current levels that should be close to equal. This is done by putting the output of two current transducers in parallel with a relay that detects current flow. With the proper connection of polarities of the CTs, if both the secondary currents are equal, no current will flow through the relay. Issues with this include the previously stated mismatc h due to CT limitations, as well as CT error mismatches, transformer’s magnetizing currents, and tap changing elements which will change the effective ratio of the transformer itself. These problems are alleviated by establishing a restraint current. The restraint current is simply the average of the secondary currents. The relay operates when the current that it sees exceeds a certain percentage of the restraint current. The smaller the percentage required, the higher the sensitivity of the relay.

Additionally, magnetizing current can cause errors during energization and fault removal, and its harmonic content can cause issues as well. The magnetizing inrush current is caused when an unloaded transformer is brought online and needs to gain the flux necessary for steady state operation to occur. This can also happen when a fault is cleared and the current changes significantly. On top of magnetizing current, transformer over-excitation can also become a problem. The saturation during these times can

cause the differential relay to react unnecessarily. Lastly, if there is a fault outside of the transformer it is possible that the CTs will saturate at different current levels. If the difference between these saturation levels is large, the differential relay will operate unnecessarily for a fault that is not within the transformer.

Computer based relays can offer solutions to all of these issues to significantly increase the accuracy of operation for a percentage differential protection scheme. The main error caused by mismatched ratios is quickly mediated by the fact that a computer can take the output from any CT and scale it according to the turns ratio necessary for the secondary currents to match up. In fact, the CTs do not even need to have secondary currents that are close to each other, but simply take the current low enough for an analog to digital conversion to be given to the computer. CTs can then be chosen based on their accuracy as well as their saturation limits in order to prevent some of the other issues discussed.

The computer itself can be given inputs on different phenomena going on to prevent unnecessary operation. For example, if the transformer is being brought online the computer can be set to recognize and ignore the issues brought about by the inrush currents. In the case of a transformer with tap changing occurring, the relay could be set up to allow for any inrush currents expected as well as change the necessary ratios on the CTs. With certain communication parameters, it could even be possible for a computer based differential relay to recognize when faults outside of the transformer will affect operation of the relay. In the field of communication, there are many opportunities to improve protection schemes.

3. Technical Code Designing Fossil Fuel Power Plants

1.1 Foreword

This code is a professional standard containing compulsory articles, and those articles are compulsory. Compulsory content in tables is indicated by notes for the table.

Since the issuance and implementation,DL5000—1994“Technical code for designing fossil fuel power plants” has played a positive role and achieved good effects in carrying out the capital construction policies of the state, reflecting the economic and technical policies, unifying and defining construction standards, ensuring adoption of advanced technology in the newly built and expanded fossil fuel power plants, realizing safe, economic, full load and steady operation and satisfying the environmental protection requirements in the construction of electric power facilities.

With the deepening of reform and advance of technology, some aspects of DL5000—1994 can no longer meet the requirements in the development of construction of electric power facilities. According to the arrangement in Item 42 of the document NO.[1999] 40“Notice on confirming standard system and revision plan item in electric power industry in 1998”of the Department of Electric Power of the State Economic and Trade Commission, the Electric Power Planning and Design General Institute organized people to conduct the revision and compilation of DL5000—1994.

In this revision and compilation, the basic policies on electric power construction have been carried out, the policy on “safe and reliable, economic and complying with national conditions” and a series of measure to control project cost conscientiously implemented, and mature and reliable design technology adopting advanced techniques actively popularized, with due consideration given to saving coal, water, power and land and controlling the size and standard of non-production facilities. Attention has been paid to adapting to the socialist market economic system, to get well prepared in design and technology for the electric power construction in the 21st century.

In this revision and compilation, no major revision has been made to the framework of DL5000—1994, only some revision, deletion and supplement have been made to the contents of relevant section, and some sections have been adjusted as appropriate.

To spreading and application of gas-steam combined recycling power generation technology, flue gas desulfurization technology and clean coal power generation technology are the development orientation of the power industry in the 21st century, however, compared with the conventional coal-firing power

generation technology, they are not so mature as there is not much practical experience in the country. Therefore, in this revision and compilation, only some fairly mature articles were prepared for perspective.

This code was proposed by the State Electric Power Corporation.

This code shall be under the charge by China Electric Power Planning and Design Association.

This code shall be interpreted by China Electric Power Planning and Design Association.

1.2 Scope

This code has specified the principles that should be followed and the construction standards in the design of large sized fossil fuel power plants. This code is applicable to the design of condensing type fossil fuel power plants with units of turbo-generator sets at capacity of 125MW—600MW,as well as fossil fuel power plants with heat supplying units at or above 50MW.It can be used as reference for units of and above 600MW.This code is applicable to the design of newly built or extension of power plants, and can be used as reference for the design of modification projects.

1.3 General Provisions

The unit capacity of power plants shall be selected in accordance with such factors as the system planning capacity, load increase rate and grid configuration. Large capacity unit with high efficiency shall be selected, provided that maximum unit capacity should not exceed 10% of the total system capacity.

There should be no more than six units in a power plant, with no more than capacity grades for the units. Turbo-generators and boilers of the same capacity should be of same type or modified type, and with the same types of associated equipment. A newly built power plant should be built in one or two phases to the planned capacity on the basis of load demand and available capital high-efficiency unit of the same type, and be constructed successively.

In power plant design, overall coordination shall be made and technical requirements shall be raised on the main auxiliary equipment and systems required, and selection shall be made among the same type of equipment on the basis of technical performance, reliability, supply conditions, prices and performance and technical service quality of manufactures. When conditions are standard series products and energy-saving products shall be selected in priority.

1.4 Site Selection

In site selection for power plants, the following condition shall be studied: grid configuration, power and heat load, fuel supply, water source, traffic, transport of fuel and large equipment, environmental

protection requirements, disposal of fly ash and slag, outgoing line corridor, geology, seismology, topography, hydrology, meteorology, land requisition and relocation, construction, and influence of surrounding industrial and mining enterprise on the power plants, so that preliminary schemes can be drawn up and justification and evaluation can be made through overall technical and economic comparison and economic efficiency analysis.

In the site selection for planning, comments shall be made on the construction scale and completion time, with proposal on the number and capacity of units to be installed.

In the site selection for engineering, comments shall be made on the construction scale and completion time, with proposal on the number and capacity of units to be installed.

In selecting power plant sites, full consideration shall be given to the outgoing conditions for connection with the grid when the power plants reach the planned capacity.

1.5 Arrangement of Main Building

The main buildings should be arranged in the order of boiler house, coal bunker bay, deaerator bay (or combined coal bunker and deaerator bay) and turbine, and their size should not exceed those of the reference design for main buildings for units of the same category. When it is deemed reasonable after technical and economic justification and according to the actual project conditions, other new forms of arrangement that can control project cost and favorable to operation, maintenance and construction can also be adopted. The comparable building volume of main building shall not exceed data of reference design of main buildings for units of the same category.

In non-severely cold regions, boilers should be in open or semi-open arrangement. In areas with severe cold or strong sandstorm, tower type boilers should be tightly enclosed with outer wall boards, and non-tower type boilers shall either be tightly enclose with outer wall boards or be arranged indoor according to the equipment features and actual condition of the project. In regions with proper climate conditions, boilers with good sealing can be arranged without top compartment and rain shield.

1.6 Boiler Equipment and Systems

The type selection of boiler equipment and technical requirements shall be as specified in “Technical Specification for Coal Fired Power Plant Boiler” SD268-1988. The type of the boiler equipment must be suited to the quality characteristics of the coal used and the allowable variation of the coal quality in the current specifications. The physical and chemical tests and analyses of the coal and its ash shall be

performed to obtain the normal and abnormal characteristic data of the coal quality.

The pressure drop from the superheater outlet of the large capacity boiler to the turbine inlet shall be 5% of the rated inlet steam pressure of the turbine. For the unit with subcritical and below parameters, the rated steam temperature at the superheater outlet shall be 3℃ higher than the rated inlet steam temperature of the turbine. At rated conditions, the pressure drops of the cold reheat steam piping, reheater and hot reheat steam piping shall be 1.5%~2.0%. 5%, 3.5%~3.0% respectively, of the HP turbine exhaust steam pressure at the operation conditions. The rated steam temperature at the reheater outlet shall be 2℃ higher than the rated inlet steam temperature of the IP turbine.

The design of the pulverizing system for boiler combustion and equipment shall be in accordance with the design of the boiler proper and its safety protection monitoring system and shall conform with the specifications is “Anti-explosive Directories of Pulverized Coal Boiler Combustion Chamber of Fossil fuel power plant” DL345.