CN101551434B - Transformer partial discharge positioning method base on ultra high frequency detection technology - Google Patents

Transformer partial discharge positioning method base on ultra high frequency detection technology Download PDF

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CN101551434B
CN101551434B CN2009100433810A CN200910043381A CN101551434B CN 101551434 B CN101551434 B CN 101551434B CN 2009100433810 A CN2009100433810 A CN 2009100433810A CN 200910043381 A CN200910043381 A CN 200910043381A CN 101551434 B CN101551434 B CN 101551434B
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transformer
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partial discharge
detection
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丁家峰
曾德文
陈孔阳
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Central South University
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Abstract

本发明公开了一种基于超高频检测技术的变压器局部放电定位方法。它包括以下步骤:利用设置在变压器内部的多个放电检测器检测变压器的超高频放电信号;将放电检测器的检测信号送到信息采集中心进行编码;将编码后的检测信号送到信号调理电路,信号调理电路对检测信号进行滤波、消除干扰和噪声信号;将滤波后的检测信号送到处理器,处理器根据各检测信号到达的先后,确定变压器局部放电的放电源位置。本发明克服了常用局部放电检测方法抗干扰能力差、灵敏度不高、测量精度低的缺陷,结构简单,可靠性高,可广泛应用于变压器内各点局部放电的高精度测量。

Figure 200910043381

The invention discloses a transformer partial discharge location method based on ultra-high frequency detection technology. It includes the following steps: using multiple discharge detectors installed inside the transformer to detect the UHF discharge signal of the transformer; sending the detection signals of the discharge detectors to the information collection center for encoding; sending the encoded detection signals to the signal conditioning The circuit and the signal conditioning circuit filter the detection signal, eliminate interference and noise signals; send the filtered detection signal to the processor, and the processor determines the discharge source position of the partial discharge of the transformer according to the arrival sequence of each detection signal. The invention overcomes the defects of poor anti-interference ability, low sensitivity and low measurement precision of the commonly used partial discharge detection method, has simple structure and high reliability, and can be widely used in high-precision measurement of partial discharge at various points in the transformer.

Figure 200910043381

Description

基于超高频检测技术的变压器局部放电定位方法Transformer partial discharge location method based on ultra-high frequency detection technology

技术领域 technical field

本发明涉及一种基于超高频检测技术的变压器局部放电定位方法。The invention relates to a transformer partial discharge location method based on ultra-high frequency detection technology.

背景技术 Background technique

电能是国家的经济命脉,与人们的日常生活和企业的正常生产紧密相关。目前我国正处于电力建设的高峰期和关键期,迫切需要研究和发展相应的超高压输变电关键技术。作为电力系统输变电关键设备,电力变压器的可靠运行对整个电力系统的安全、经济运行具有重要意义。Electric energy is the economic lifeline of the country and is closely related to people's daily life and normal production of enterprises. At present, my country is in the peak and critical period of electric power construction, and there is an urgent need to research and develop corresponding key technologies for ultra-high voltage power transmission and transformation. As a key equipment for power transmission and transformation in power systems, the reliable operation of power transformers is of great significance to the safe and economical operation of the entire power system.

目前大型电力变压器多为油浸式电力变压器,其绝缘结构主要由油、纸、纸板等构成的固体-油绝缘结构。电力变压器在制造过程中会形成气泡、裂缝、悬浮导电质点和电极毛刺等局部缺陷,从而导致绝缘体内部或表面上某些区域电场强度高于平均电场强度。当这些区域的击穿场强低于平均击穿场强时,会发生放电,而其他区域仍保持绝缘特性,从而形成局部放电的现象。At present, most large-scale power transformers are oil-immersed power transformers, and their insulation structure is mainly a solid-oil insulation structure composed of oil, paper, cardboard, etc. During the manufacturing process of power transformers, local defects such as air bubbles, cracks, suspended conductive particles and electrode burrs will be formed, which will cause the electric field strength in some areas inside or on the surface of the insulator to be higher than the average electric field strength. When the breakdown field strength in these areas is lower than the average breakdown field strength, discharge will occur, while other areas still maintain insulating properties, thus forming the phenomenon of partial discharge.

变压器局部放电时伴有电脉冲、电磁辐射、声、光、局部发热以及放电导致绝缘材料分解出气体等现象,通过这些现象可以检测局部放电。在常用的局部放电检测方法中,脉冲电流法、DGA法和超声波法是应用比较广泛的。Partial discharge of transformers is accompanied by phenomena such as electric pulses, electromagnetic radiation, sound, light, local heating, and discharges that cause insulating materials to decompose gases. Partial discharges can be detected through these phenomena. Among the commonly used partial discharge detection methods, pulse current method, DGA method and ultrasonic method are widely used.

脉冲电流法是研究最早、应用最广泛的一种检测方法,它通过将阻抗接入到测量回路中来检测,但其测量灵敏度受到耦合阻抗的限制,测量频率低、频带窄,包含的信息量少,且抗干扰能力差,无法有效应用于现场的在线监测。DGA法是通过检测变压器油分解产生的各种气体的组成和浓度来确定故障状态,但油气分析是一个长期的监测过程,因而无法发现突发性故障,且该方法无法进行故障定位。超声波法是通过检测变压器局放产生的超声波信号来测量局放的大小和位置,但受到超声波传播的时延误差的制约,超声波定位的准确度和灵敏度不高。The pulse current method is the earliest and most widely used detection method. It detects by connecting the impedance into the measurement circuit, but its measurement sensitivity is limited by the coupling impedance. The measurement frequency is low, the frequency band is narrow, and the amount of information contained and the anti-interference ability is poor, so it cannot be effectively applied to on-site online monitoring. The DGA method determines the fault state by detecting the composition and concentration of various gases produced by the decomposition of transformer oil. However, oil and gas analysis is a long-term monitoring process, so sudden faults cannot be found, and this method cannot be used for fault location. Ultrasonic method is to measure the size and position of partial discharge by detecting the ultrasonic signal generated by transformer partial discharge, but it is limited by the time delay error of ultrasonic propagation, and the accuracy and sensitivity of ultrasonic positioning are not high.

发明内容 Contents of the invention

为了解决现有变压器局部放电的定位检测方法存在的上述技术问题,本发明提供一种基于超高频技术的变压器局部放电的定位方法。本发明能检测出局部放电的位置,且准确度和灵敏度更好。In order to solve the above-mentioned technical problems existing in the existing transformer partial discharge location detection method, the present invention provides a transformer partial discharge location method based on ultra-high frequency technology. The invention can detect the position of partial discharge with better accuracy and sensitivity.

本发明解决其技术问题所采用的技术方案是:The technical solution adopted by the present invention to solve its technical problems is:

将编码后的检测信号送到处理器,处理器先对检测信号进行滤波、消除干扰和噪声信号,再根据各检测信号到达时间的先后,确定变压器局部放电的放电源位置,若A(xa,ya)、B(xb,yb)、C(xc,yc)分别为检测点A、B、C的位置,待定位信号源的坐标为M(xm,ym),根据信号的传播时间能确定信号源到A、B、C三点的距离为r1,r2,r3,由三边关系得到:The coded detection signal is sent to the processor, the processor first filters the detection signal, eliminates interference and noise signals, and then determines the discharge source position of the partial discharge of the transformer according to the arrival time of each detection signal, if A(x a , y a ), B(x b , y b ), C(x c , y c ) are the positions of detection points A, B, and C respectively, and the coordinates of the signal source to be located are M(x m , y m ), According to the propagation time of the signal, the distances from the signal source to points A, B, and C can be determined as r 1 , r 2 , and r 3 , which can be obtained from the trilateral relationship:

(( xx mm -- xx aa )) 22 ++ (( ythe y mm -- ythe y aa )) 22 == rr 11

(( xx mm -- xx bb )) 22 ++ (( ythe y mm -- ythe y bb )) 22 == rr 22

(( xx mm -- xx cc )) 22 ++ (( ythe y mm -- ythe y cc )) 22 == rr 33

由上述公式可以求得待定位点M的坐标为:From the above formula, the coordinates of the point M to be located can be obtained as:

xx mm ythe y mm == 22 (( xx aa -- xx cc )) 22 (( ythe y aa -- ythe y cc )) 22 (( xx bb -- xx cc )) 22 (( ythe y bb -- ythe y cc )) -- 11 xx aa 22 -- xx cc 22 ++ ythe y aa 22 -- ythe y cc 22 ++ rr 33 22 -- rr 11 22 xx bb 22 -- xx cc 22 ++ ythe y bb 22 -- ythe y cc 22 ++ rr 33 22 -- rr 22 22 ..

本发明的技术效果在于:本发明利用设置在变压器内部的多个放电检测器检测变压器的超高频放电信号,经编码后送到处理器处理,处理器根据各检测信号到达的先后,可以准确测量出变压器的放电位置,提高了局部放电源的定位精度,并保证定位结果的准确性和可靠性。The technical effect of the present invention is that: the present invention utilizes a plurality of discharge detectors arranged inside the transformer to detect the ultra-high frequency discharge signals of the transformer, and sends them to the processor for processing after encoding, and the processor can accurately The discharge position of the transformer is measured, which improves the positioning accuracy of the partial discharge source and ensures the accuracy and reliability of the positioning result.

下面结合附图对本发明作进一步的说明。The present invention will be further described below in conjunction with the accompanying drawings.

附图说明 Description of drawings

图1是实现本发明的系统构成结构图。Fig. 1 is a structural diagram of a system for realizing the present invention.

图2是本发明的流程图。Fig. 2 is a flow chart of the present invention.

图3是本发明的定位算法原理图。Fig. 3 is a schematic diagram of the positioning algorithm of the present invention.

具体实施方式 Detailed ways

参见图1、图2,图1是实施本发明的系统构成示意图。系统包括设置在变压器内部的多个放电检测器、信息采集中心、信号调理电路、处理器。图2是本发明的流程图。放电检测器安装在在变压器内部,它们作为局部放电定位的参考节点,分布在变压器油箱的不同位置处。当变压器油箱内局部放电产生放电陡脉冲时,会同时激发产生几百兆赫兹以上的超高频电磁波。油箱内的各个放电检测器可以检测接收到该放电源产生的超高频(UHF)信号,直接接收局部放电产生的超高频电磁波。信息采集中心安装在变压器油箱外部,采用光纤连接放电检测器,信息采集中心按照规定的格式对检测信号进行存储、转发,信号调理电路对检测信号进行滤波、消除干扰和噪声信号,再由处理器进行运算处理,处理器根据各检测信号到达的先后顺序,采用TOA(Time of Arrive)算法对放电源进行定位。Referring to Fig. 1 and Fig. 2, Fig. 1 is a schematic diagram of a system for implementing the present invention. The system includes a plurality of discharge detectors, an information collection center, a signal conditioning circuit and a processor arranged inside the transformer. Fig. 2 is a flow chart of the present invention. Discharge detectors are installed inside the transformer, they serve as reference nodes for partial discharge location, and are distributed in different positions of the transformer oil tank. When the partial discharge in the transformer oil tank produces a steep discharge pulse, it will simultaneously stimulate and generate ultra-high frequency electromagnetic waves above several hundred megahertz. Each discharge detector in the fuel tank can detect and receive the ultra-high frequency (UHF) signal generated by the discharge source, and directly receive the UHF electromagnetic wave generated by the partial discharge. The information collection center is installed outside the transformer oil tank and connected to the discharge detector by optical fiber. The information collection center stores and forwards the detection signals according to the specified format, and the signal conditioning circuit filters the detection signals to eliminate interference and noise signals, and then the processor Perform calculation processing, the processor uses the TOA (Time of Arrive) algorithm to locate the discharge source according to the arrival sequence of each detection signal.

图3是本发明的定位算法原理图。图示中有三个已知检测点A、B、C,未知节点M到三个已知节点的距离为r1,r2,r3。根据三条边的关系式,可以求得M点坐标。Fig. 3 is a schematic diagram of the positioning algorithm of the present invention. In the illustration, there are three known detection points A, B, and C, and the distances from the unknown node M to the three known nodes are r 1 , r 2 , and r 3 . According to the relational expressions of the three sides, the coordinates of point M can be obtained.

所述的TOA定位算法至少需要三个定位参考节点,可以实现精确定位,是三角测量定位技术中的一种重要方法,其定位原理为:The TOA positioning algorithm needs at least three positioning reference nodes, which can realize accurate positioning, and is an important method in triangulation positioning technology, and its positioning principle is:

假设已知的三个定位参考节点的坐标为:A(xa,ya)、B(xb,yb)、C(xc,yc),待定位信号源的坐标为M(xm,ym)。在已知超高频信号传输速率的情况下,根据信号的传播时间能确定信号源到A、B、C三点的距离为r1,r2,r3。由三边关系得到:Suppose the coordinates of the three known positioning reference nodes are: A(x a , y a ), B(x b , y b ), C(x c , y c ), and the coordinates of the signal source to be positioned are M(x m , y m ). When the UHF signal transmission rate is known, the distances from the signal source to points A, B, and C can be determined as r 1 , r 2 , and r 3 according to the propagation time of the signal. From the tripartite relationship we get:

(( xx mm -- xx aa )) 22 ++ (( ythe y mm -- ythe y aa )) 22 == rr 11 -- -- -- (( 11 ))

(( xx mm -- xx bb )) 22 ++ (( ythe y mm -- ythe y bb )) 22 == rr 22 -- -- -- (( 22 ))

(( xx mm -- xx cc )) 22 ++ (( ythe y mm -- ythe y cc )) 22 == rr 33 -- -- -- (( 33 ))

由公式(1)(2)(3)可以求得待定位点M的坐标为:The coordinates of the point M to be located can be obtained from the formula (1)(2)(3):

xx mm ythe y mm == 22 (( xx aa -- xx cc )) 22 (( ythe y aa -- ythe y cc )) 22 (( xx bb -- xx cc )) 22 (( ythe y bb -- ythe y cc )) -- 11 xx aa 22 -- xx cc 22 ++ ythe y aa 22 -- ythe y cc 22 ++ rr 33 22 -- rr 11 22 xx bb 22 -- xx cc 22 ++ ythe y bb 22 -- ythe y cc 22 ++ rr 33 22 -- rr 22 22 -- -- -- (( 44 )) ..

以上所述仅是本发明的优选实施方式,在不脱离本发明的基本原理的情况下,所做的修改和润饰,也为本发明的保护范围。The above descriptions are only preferred implementations of the present invention, and modifications and embellishments made without departing from the basic principles of the present invention also fall within the scope of protection of the present invention.

Claims (1)

1. transformer partial discharge positioning method based on ultra high frequency detection technology may further comprise the steps:
Utilization is arranged on the ultra high frequency discharge signal that the inner a plurality of discharge detectors of transformer detect transformer;
The detection signal of discharge detector is delivered to information collecting center encodes;
Detection signal behind the coding is delivered to processor, and processor earlier carries out filtering, eliminates and disturb and noise signal detection signal, again according to each detection signal priority of time of arrival, confirms the discharge source position of partial discharge of transformer, if A (x a, y a), B (x b, y b), C (x c, y c) being respectively the position of check point A, B, C, the coordinate of signal source to be positioned is M (x m, y m), can confirm that according to the travel-time of signal signal source is r to the distance of 3 of A, B, C 1, r 2, r 3, system obtains by three frontier junctures:
( x m - x a ) 2 + ( y m - y a ) 2 = r 1 - - - ( 1 )
( x m - x b ) 2 + ( y m - y b ) 2 = r 2 - - - ( 2 )
( x m - x c ) 2 + ( y m - y c ) 2 = r 3 - - - ( 3 )
By formula (1) (2) (3) can be in the hope of the coordinate of to be positioned some M:
x m y m = 2 ( x a - x c ) 2 ( y a - y c ) 2 ( x b - x c ) 2 ( y b - y c ) - 1 x a 2 - x c 2 + y a 2 - y c 2 + r 3 2 - r 1 2 x b 2 - x c 2 + y b 2 - y c 2 + r 3 2 - r 2 2 - - - ( 4 ) .
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107576892A (en) * 2017-07-26 2018-01-12 国网上海市电力公司 A kind of noise-reduction method for partial discharge pulse's measurement

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102253127B (en) * 2011-07-01 2014-01-29 西安交通大学 L-Shape Ultrasonic Array Sensor for Partial Discharge Localization in Transformer
CN102279354B (en) * 2011-07-01 2013-07-31 西安交通大学 Cruciform ultrasound array sensor and method for positioning transformer partial discharge
CN102508124B (en) * 2011-10-18 2013-12-25 广西电网公司电力科学研究院 Detection method of partial discharge of electrical equipment
CN102445619A (en) * 2011-11-17 2012-05-09 北京交通大学 Power transformer on-line state monitoring system based on audio information
CN102841294B (en) * 2011-12-23 2015-02-11 湖北省电力公司电力科学研究院 Method for identifying signal and interference signal in ultrahigh frequency partial discharge detection in electrical equipment
CN103336231B (en) * 2013-07-01 2015-09-09 杭州电子科技大学 The Neural Networks Learning Algorithm that shelf depreciation AE position is detected
CN104062568B (en) * 2014-07-08 2017-03-01 国家电网公司 A kind of compound eye type optical fiber EFPI shelf depreciation angle detecting system
CN105403814A (en) * 2014-08-11 2016-03-16 国家电网公司 Positioning method and device for partial discharge source of transformer
CN105891689A (en) * 2016-04-14 2016-08-24 国家电网公司 Partial discharge integrated probe based on capacitance voltage division method VFTO measurement sensor
CN106483435A (en) * 2016-11-24 2017-03-08 国网新疆电力公司电力科学研究院 Transformer belt electric detection means
JP6834002B2 (en) 2016-12-07 2021-02-24 アーベーベー・シュバイツ・アーゲーABB Schweiz AG Systems and methods for inspecting machines
CN107132459B (en) * 2017-03-31 2019-07-09 国网浙江省电力有限公司电力科学研究院 A Transformer Partial Discharge Ultrasonic Positioning Method
CN107102244B (en) * 2017-05-25 2019-11-22 国网浙江省电力有限公司电力科学研究院 Discharge source location method for GIS UHF partial discharge on-line monitoring device
CN108490318A (en) * 2018-02-05 2018-09-04 天津大学 Shelf depreciation whole station synthesized positioning method based on Waveform Matching and sensor
CN108535617B (en) * 2018-07-09 2020-04-17 闽江学院 Partial discharge positioning method and positioning system of switch cabinet
CN109901037B (en) * 2019-04-04 2020-09-15 中国科学院电工研究所 Determination method of high frequency transformer factory insulation test voltage based on material insulation life

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2590002Y (en) * 2002-09-18 2003-12-03 新疆特变电工股份有限公司 Transformer partial discharge online monitor
CN2736782Y (en) * 2004-08-09 2005-10-26 华北电力大学(北京) Voltage transformer local discharge ultrahigh frequency (UHF) online monitoring device
CN1932539A (en) * 2006-10-12 2007-03-21 重庆大学 Transformer partial discharge super high frequency detector

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN2590002Y (en) * 2002-09-18 2003-12-03 新疆特变电工股份有限公司 Transformer partial discharge online monitor
CN2736782Y (en) * 2004-08-09 2005-10-26 华北电力大学(北京) Voltage transformer local discharge ultrahigh frequency (UHF) online monitoring device
CN1932539A (en) * 2006-10-12 2007-03-21 重庆大学 Transformer partial discharge super high frequency detector

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
唐炬等.用于PD信号定位的多样本能量相关搜索提取时间差算法.《08全国电工测试技术学术交流会论文集》.2008,5461. *
王颂等.局部放电超高频检测系统标定方法的研究现状及发展.《高压电器》.2007,第43卷(第1期),59-64. *
赵晓辉等.超高频方法在变压器局部放电检测中的应用.《高电压技术》.2007,第33卷(第8期),111-114. *
邓宏贵等.基因多点交叉遗传算法在变压器故障诊断中的应用.《电网技术》.2004,第28卷(第24期),1-4. *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107576892A (en) * 2017-07-26 2018-01-12 国网上海市电力公司 A kind of noise-reduction method for partial discharge pulse's measurement

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