【作者】 张志；

【导师】 李红斌；

【作者基本信息】 华中科技大学 ， 电气工程， 2013， 博士

【摘要】 作为智能电网的重要组成部分,数字化变电站的出现及发展大大促进了智能电网的进步。而作为数字化变电站中一次系统的传感元件,电子式互感器是所有继电保护装置及电能计量装置的数据源头。然而,由于电子式互感器在可靠性、使用寿命、连续运行、电磁兼容等方面,还需要进一步的积累运行经验。因此,电子式互感器的在线校验、实时监测尤为重要。但是目前缺乏可以在带电状态下对电子式互感器性能进行监测的有效手段,大大限制了电子式互感器的性能提高及完善。本文正是在南方电网科技项目的资助和实际工程项目的需求牵引下,重点针对带电操作方式、高准确度标准电流传感头设计、非线性负荷下的数据处理算法等关键技术,对当前数字输出电子式电流互感器在线校验技术进行了较为深入的探讨和研究。从校验方式出发,提出一种新的电子式电流互感器校验方式,在国内首次实现对数字输出电子式电流互感器的准确度在线校验,并研制出国内首台符合IEC61850-9-2标准的电子式互感器在线校验系统,该系统具有0.05级的准确度,可以校验同步方式为B码、PPS,额定电流为600A和1500A,0.2S级的电子式电流互感器。到目前为止,该系统已经在贵州省电网公司多个数字化变电站进行现场测试,挂网运行结果表明,系统准确度高、运行状态良好、现场操作方便。首先针对校验系统需要带电操作的问题,考虑到带电操作的安全性,采用地电位作业法,设计了一种基于绝缘操作杆的钳形操作机构,在地面通过钳形操作机构可以完成传感头的带电安装及拆卸；其次,提出一种组合式钳形电流传感头构成标准电流通道的技术方案。采用钳形铁芯传感头作为标准电流互感器,准确度高,体积小,并针对气隙对钳形铁芯传感头准确度影响较大的问题,采用钳形空心传感头作为铁芯传感头闭合完好的判断依据。由于钳形空心传感头的角差几乎不受气隙的影响,而钳形铁芯传感头的角差受气隙影响较大,以两者角差一致性为特征量,用来检测钳形铁芯传感头的闭合程度,提高了校验准确度。另外,本文在分析电网波形成分及以往算法的基础上,提出一种基于数据预处理的加二阶汉宁卷积窗的高准确度基波提取算法,在现场复杂的非线性负荷校验环境下,该算法针对有频率波动的电网,在抑制频谱泄漏、间谐波及谱间干扰等引起的误差方面,有更高的准确度。给出了系统具体的设计及实现方案。硬件设计主要考虑到标准通道的高准确度采集,在分辨率、动态范围两个方面进行了详细分析；同时考虑到稳定性及可靠性,从采集装置的带宽设计、接地及屏蔽等几个方面做出了具体的抗电磁干扰设计。另外,上位机软件主要实现了组合式传感头特征量判断功能、标准通道数据采集功能、合并单元数据接收及解码功能、基波提取算法及误差计算功能、数据的显示、记录和存储等功能。以贵州白城110kV变电站1500A组合式电子式互感器为试验对象,将全文所研究的方法和技术进行了整体验证和应用。挂网运行结果表明,该系统能够在不断电的情况下完成对电子式电流互感器的实时校验。另外,在论文研究内容基础上,编制了“电子式互感器在线校验规范”及“电子式互感器在线校验作业指导书”,为后续电子式互感器的在线校验提供了校验依据,并参与编写了《贵州电网数字化变电站计量装置在线检测规范》,为电子式互感器的在线监测及分析提供检测规范。更多还原

【Abstract】 As an important part of smart grid, the occurrence and development of digital substation has largely promoted the progress of smart grid. And as the primary sensor elements in digital substations, electronic transformers (ETs) are data sources of all relay protection devices and electric energy metering equipments. Comparing with traditional transformers, ETs are used widely because there are outstanding features including simple insulation, digital output, wide dynamic range and the frequency band. But ETs are newborn things which need further running experience including reliability, working life and EMC. On-line calibration of ETs periodically or real-time can greatly improved reliability during running time. At present, calibration of both traditional transformers and ETs stayed on the off-line calibration lack of efficient measures for on-line monitoring performance of ETs. Because of this, there is no related calibration specification which limited the performance monitoring and improving of ETs and the application in digital substation. In the traction of China Southern Power Grid and real project, the paper conducted more thorough research to the on-line calibration technology of ETs with digital output focus on the portability of on-line operations, standard current sensor design and data processing algorithm in non-linear load. The main researches and achievements are as follows.A new calibration method for electronic current transformers (ECTs) was proposed. The proposed system can reach the precision class up to0.05and the system can calibrate the ETs for0.2S in the range of600A-1500A at rated current which the synchronization method can be PPS or IRIG-B. Actual onsite calibration shows that the system has high-accuracy, and is easy to operate with satisfactory stability.Earth potential working was used in the system and a clamp operating mechanism based on insulated operating rod was designed. The performance differences were systemically analyzed between a clamp-shape iron core sensor and a clamp-shape air core sensor and a high-accuracy method based on combined clamp-shape current sensors was proposed originally according with the performance differences in the paper. Clamp-shape current sensor when open and close, may be the cause of opening cannot be closed completely, even if there is air gap only micron, will also cause a significant reduction in the standard current accuracy. In online calibration under the condition of high voltage, air gap exists or not, the operator can’t be judged by conventional means of low pressure.Principle deduction and simulation were carried out and experimental analysis details were made for the air-gap influence on clamp-shape sensors. The actual tests results show that the novelty method can make judgment on air-gap of amp-shape iron core sensors accurately. A high-accuracy algorithm is one of the most important key technologies and a new method based on data preprocessing was proposed after the analysis of waveform components and algorithms before, In complicated non-linear load calibration environments, the algorithm has high accuracy in inhibition of errors resulted from spectral leakage, frequency fluctuation, inter-harmonics and mutual interference.A detailed design of on-line calibration system was given in the paper. Digital sampling of analog output signal of standard channel is the factor influencing accuracy of calibration system so the paper introduced the influences on calibration accuracy in different parameters from two aspects:high resolution and wide dynamic range. Meanwhile, considering stability and reliability, EMC design was made from bandwidth design, ground and shielding. Four improvements were given according to the design of data frame program. PC software mainly realizes the modular sensor head characteristic judgment function, standard channel data acquisition, merging unit data reception and decoding, the fundamental wave extraction algorithm and error calculation, data display, record, storage, and other functions.At the end of this paper, a series of performances testing verification and application of the method and technology of the whole paper were made for the combined electronic transformers (1500A/5A) in Bai Cheng110kV substation in Gui Zhou province. The experimental results prove that the on-line calibration system can realize the real-time calibration of ETs which provide the data guarantee for the running of substation and the running stability and quality were improved. Besides that, on-site calibration norm and on-line monitoring specification of ETs and electric energy metering equipments were established which can provide calibration norm for the on-line calibration of ETs.更多还原