JP5494929B2 - Ground fault current detection method and detection apparatus - Google Patents

Ground fault current detection method and detection apparatus Download PDF

Info

Publication number
JP5494929B2
JP5494929B2 JP2009205700A JP2009205700A JP5494929B2 JP 5494929 B2 JP5494929 B2 JP 5494929B2 JP 2009205700 A JP2009205700 A JP 2009205700A JP 2009205700 A JP2009205700 A JP 2009205700A JP 5494929 B2 JP5494929 B2 JP 5494929B2
Authority
JP
Japan
Prior art keywords
leakage current
ground fault
component
current
ground
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
JP2009205700A
Other languages
Japanese (ja)
Other versions
JP2011058826A (en
Inventor
俊介 鹿野
正仁 吉田
悟志 町田
義紘 圓淨
Original Assignee
富士電機機器制御株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 富士電機機器制御株式会社 filed Critical 富士電機機器制御株式会社
Priority to JP2009205700A priority Critical patent/JP5494929B2/en
Publication of JP2011058826A publication Critical patent/JP2011058826A/en
Application granted granted Critical
Publication of JP5494929B2 publication Critical patent/JP5494929B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Description

本発明は、三相配電系統の漏電電流から対地絶縁抵抗の不良(以下、単に絶縁不良ともいう)に起因する地絡電流を検出する地絡電流検出方法及び検出装置に関し、特に、三相配電系統の絶縁監視装置や漏電リレー等に適用して好適な技術に関するものである。
なお、電路充電部から大地に流れる電流に関する定義としては、JIS C 8201-2-2「低圧開閉装置及び制御装置−第2−2部:漏電遮断器」が知られている。このため、本件出願では、このJIS C 8201-2-2を参考として以下の定義を用いることとする。
(1)地絡電流:絶縁不良に起因して、電路充電部から対地絶縁抵抗を介して大地に流れる電流(後述するように、記号I0rと表記する。)
(2)漏洩電流:電路充電部から対地静電容量を介して大地に流れる電流(記号I0cと表記する。)
(3)漏電電流:上記(1)の地絡電流と(2)の漏洩電流とのベクトル和(記号Iと表記する。)
The present invention relates to a ground fault current detection method and a detection device for detecting a ground fault current caused by a fault in ground insulation resistance (hereinafter also simply referred to as faulty insulation) from a leakage current of a three-phase power distribution system, and more particularly to a three-phase power distribution. The present invention relates to a technique suitable for application to a system insulation monitoring device, a leakage relay, or the like.
In addition, JIS C 8201-2-2 “Low voltage switchgear and control device—Part 2-2: Earth leakage breaker” is known as a definition related to the current flowing from the electric circuit charging unit to the ground. Therefore, in this application, the following definitions will be used with reference to JIS C 8201-2-2.
(1) Ground fault current: Current that flows from the current path charging section to the ground via the ground insulation resistance due to poor insulation (denoted as symbol I 0r as described later).
(2) Leakage current: Current that flows from the electric circuit charging unit to the ground via the ground capacitance (denoted as I0c )
(3) Leakage current: Vector sum of the ground fault current of (1) and the leakage current of (2) (denoted as symbol I 0 ).
交流配電系統の地絡電流または対地絶縁抵抗を測定して絶縁監視を行う従来技術としては、特許文献1,2に記載されたものが知られている。
例えば、特許文献1には、配電系統の漏電電流から第1周波数成分(例えば基本波成分)と第2周波数成分(例えば第5調波成分)とを抽出し、第2周波数成分については電圧の第2周波数成分が第1周波数成分に等しいときの値に換算することにより、対地絶縁抵抗に起因して流れる地絡電流値は第1周波数成分及び第2周波数成分が等しく、対地静電容量等に起因して流れる漏洩電流値は第1周波数成分及び第2周波数成分に比例して大きさが異なることを利用して、漏洩電流と地絡電流とのベクトル位相をそれぞれ求め、対地絶縁抵抗による第1周波数成分、すなわち地絡電流の基本波成分(三相接地回路では、二相の地絡電流のベクトル和の電流値)を求めるようにした絶縁監視装置が開示されている。
特許文献2には、配電系統の電圧及び電流の第3n(nは整数)次高調波成分を2種類抽出し、これらの第3n次高調波成分が三相とも同相になることを利用して、抵抗分及び静電容量分を含む各高調波成分のアドミタンスに関する連立方程式を解くことにより、前記抵抗分つまり対地絶縁抵抗値を求める抵抗計測方法または監視装置等が開示されている。
As conventional techniques for monitoring insulation by measuring a ground fault current or ground insulation resistance of an AC distribution system, those described in Patent Documents 1 and 2 are known.
For example, in Patent Document 1, a first frequency component (for example, a fundamental wave component) and a second frequency component (for example, a fifth harmonic component) are extracted from the leakage current of the distribution system, and the second frequency component is a voltage. By converting to a value when the second frequency component is equal to the first frequency component, the ground fault current value caused by the ground insulation resistance is equal to the first frequency component and the second frequency component. Using the fact that the leakage current value caused by the difference in magnitude in proportion to the first frequency component and the second frequency component, the vector phase of the leakage current and the ground fault current is obtained respectively, and the ground insulation resistance An insulation monitoring device is disclosed in which a first frequency component, that is, a fundamental component of a ground fault current (in the three-phase grounding circuit, a current value of a vector sum of two-phase ground fault currents) is disclosed.
Patent Document 2 utilizes the fact that two types of 3n (n is an integer) harmonic component of the voltage and current of the distribution system are extracted, and that these 3n harmonic components are in phase with all three phases. In addition, a resistance measuring method or a monitoring device for obtaining the resistance component, that is, the ground insulation resistance value by solving simultaneous equations relating to the admittance of each harmonic component including the resistance component and the capacitance component is disclosed.
また、他の従来技術として、三相配電系統において各相の対地静電容量がバランスしているという仮定のもとで、測定した漏電電流から対地絶縁抵抗の劣化による地絡電流を計算するものがある。
例えば、特許文献3には、接地線に流れる漏電電流と接地相ではない一相の基準電圧とに基づいて地絡電流を検出する場合において、接地相を除く二相の一方または双方にて地絡電流が発生した場合にも所望の精度で絶縁状態を検出できるように、前記基準電圧の位相を所定角度ずらして地絡電流を演算するようにした絶縁監視装置が開示されている。
特許文献4には、測定した漏電電流の位相角及び実効値から対地絶縁抵抗の劣化による地絡電流を算出し、この地絡電流と別途算出した電圧実効値とを用いて対地絶縁抵抗値を算出すると共に、前記地絡電流が所定値を超えた場合に被測定電路を遮断するようにした漏洩電流遮断装置が開示されている。
Another conventional technique is to calculate the ground fault current due to the deterioration of the ground insulation resistance from the measured leakage current under the assumption that the ground capacitance of each phase is balanced in a three-phase distribution system. There is.
For example, in Patent Document 3, in the case where a ground fault current is detected based on a leakage current flowing in a ground line and a one-phase reference voltage that is not a ground phase, grounding is performed in one or both of two phases excluding the ground phase. An insulation monitoring device is disclosed in which a ground fault current is calculated by shifting the phase of the reference voltage by a predetermined angle so that an insulation state can be detected with a desired accuracy even when a fault current occurs.
In Patent Document 4, the ground fault current due to the deterioration of the ground insulation resistance is calculated from the phase angle and effective value of the measured leakage current, and the ground insulation resistance value is calculated using the ground fault current and the separately calculated voltage effective value. There is disclosed a leakage current interrupting device that calculates and interrupts an electric circuit to be measured when the ground fault current exceeds a predetermined value.
特許第4143463号公報(段落[0007]〜[0029]、図1,図2等)Japanese Patent No. 4143463 (paragraphs [0007] to [0029], FIG. 1, FIG. 2, etc.) 特許第4167872号公報(段落[0024]〜[0036]等)Japanese Patent No. 4167872 (paragraphs [0024] to [0036] etc.) 特開2001−242205号公報(段落[0034]〜[0036],[0042]〜[0061]、図1〜図3等)JP 2001-242205 A (paragraphs [0034] to [0036], [0042] to [0061], FIGS. 1 to 3 and the like) 特許第4159590号公報(段落[0029]〜[0036]、図1〜図6等)Japanese Patent No. 4159590 (paragraphs [0029] to [0036], FIGS. 1 to 6 etc.)
特許文献1及び特許文献2に係る従来技術は、基本波成分と高調波成分、または二種類の高調波成分の組み合わせ演算により、漏電電流から地絡電流をベクトル合成によって直接演算するものであり、配電系統の対地静電容量がアンバランスである場合にも適用可能なことが示されている。しかしながら、地絡電流をベクトル合成により算出するためには、概して複雑な演算処理が必要である。
また、特許文献3及び特許文献4に係る従来技術は、何れも配電系統の対地静電容量がバランスしていることを前提としており、対地静電容量にアンバランスがある電路では、地絡電流の演算値に誤差が生じるという問題がある。
The prior arts related to Patent Document 1 and Patent Document 2 directly calculate a ground fault current from a leakage current by vector synthesis by a combination calculation of a fundamental wave component and a harmonic component, or two types of harmonic components, It is shown that the present invention can also be applied when the ground capacitance of the distribution system is unbalanced. However, in order to calculate the ground fault current by vector synthesis, generally complicated calculation processing is required.
The prior arts related to Patent Document 3 and Patent Document 4 are all premised on the fact that the ground capacitance of the distribution system is balanced, and in the electric circuit where the ground capacitance is unbalanced, the ground fault current There is a problem that an error occurs in the calculated value.
そこで、本発明の解決課題は、配電系統の対地静電容量がアンバランスの場合にも、対地絶縁抵抗の劣化に起因する地絡電流を高精度かつ容易に算出可能とした地絡電流検出方法及び検出装置を提供することにある。   Therefore, a problem to be solved by the present invention is to provide a ground fault current detection method capable of easily and accurately calculating a ground fault current due to deterioration of ground insulation resistance even when the ground capacitance of the distribution system is unbalanced. And providing a detection device.
上記課題を解決するため、請求項1に係る地絡電流検出方法は、三相デルタ結線の交流電源を有し、かつ一相が接地された三相配電系統を対象として、前記配電系統の漏電電流と、前記漏電電流の線間電圧に対する位相角とを用いて、前記配電系統の対地絶縁抵抗に起因した地絡電流を検出する地絡電流検出方法において、
前記配電系統の対地静電容量のアンバランスに起因する漏洩電流の高調波成分により、または、漏洩電流の高調波成分及び基本波成分の組み合わせにより、漏電電流基本波成分のアンバランスを補正する手段であって、前記高調波成分が第n(nは3以上の奇数)調波成分であるときに、線間電圧の第n調波成分を線間電圧の基本波成分の1/nとしたときの前記漏洩電流の第n調波成分の値を用いて前記漏電電流基本波成分のアンバランスを補正する手段を備え、
前記アンバランスを補正した漏電電流基本波成分とこの漏電電流基本波成分の線間電圧基本波成分に対する位相角とを用いて地絡電流を演算する処理を、複数種類の第n調波成分につき実行して複数の地絡電流を求め、そのうちの一つを選択するものである。
In order to solve the above-described problem, a ground fault current detection method according to claim 1 is directed to a three-phase power distribution system having a three-phase delta-connected AC power source and one phase grounded. In a ground fault current detection method for detecting a ground fault current due to a ground insulation resistance of the distribution system using a current and a phase angle with respect to a line voltage of the leakage current,
Means for correcting the unbalance of the leakage current fundamental wave component by the harmonic component of the leakage current caused by the unbalance of the electrostatic capacitance to the ground of the distribution system or by the combination of the harmonic component and the fundamental wave component of the leakage current When the harmonic component is the nth (n is an odd number of 3 or more) harmonic component, the nth harmonic component of the line voltage is set to 1 / n of the fundamental wave component of the line voltage. Means for correcting an unbalance of the leakage current fundamental wave component using a value of the nth harmonic component of the leakage current when
The process of calculating the ground fault current with the phase angle for the line voltage fundamental component of the leakage current fundamental wave component of the leakage current fundamental component Toko obtained by correcting the imbalance, per a plurality of types of the n harmonic components This is executed to obtain a plurality of ground fault currents, and one of them is selected .
求項2に係る地絡電流検出方法は、請求項1に記載した地絡電流検出方法において、前記三相配電系統のうちの非接地二相の対地絶縁抵抗による地絡電流のスカラー和を演算するものである。 Ground fault current detecting method according to Motomeko 2, in ground fault current detecting method according to claim 1, the scalar sum of the ground fault current due to ground insulation resistance of an ungrounded two phases of the three-phase power distribution system It is to calculate.
請求項3に係る地絡電流検出装置は、三相デルタ結線の交流電源を有し、かつ一相が接地された三相配電系統を対象として、前記配電系統の漏電電流と、前記漏電電流の線間電圧に対する位相角とを用いて、前記配電系統の対地絶縁抵抗による地絡電流を演算する地絡電流検出装置において、
前記配電系統の漏電電流を検出する手段と、前記配電系統の線間電圧を検出する手段と、前記漏電電流及び線間電圧から基本波成分及び高調波成分を抽出する手段と、前記漏電電流及び線間電圧から基本波成分及び高調波成分を抽出する際に前記地絡電流検出装置の内部フィルタにより減衰した信号を、前記高調波成分の次数に応じて補償する手段と、前記漏電電流の前記線間電圧に対する位相角を検出する手段と、前記配電系統の対地静電容量のアンバランスに起因する前記漏洩電流の高調波成分により、または、漏洩電流の高調波成分及び基本波成分の組み合わせにより、漏電電流基本波成分のアンバランスを補正し、前記アンバランスを補正した漏電電流基本波成分と、この漏電電流基本波成分の線間電圧基本波成分に対する位相角とを用いて地絡電流を演算する手段と、を備えたものである
A ground fault current detection device according to a third aspect of the present invention is directed to a three-phase distribution system having a three-phase delta-connected AC power source and one phase of which is grounded, and the leakage current of the distribution system and the leakage current In the ground fault current detection device that calculates the ground fault current due to the ground insulation resistance of the distribution system using the phase angle with respect to the line voltage,
Means for detecting a leakage current of the distribution system; means for detecting a line voltage of the distribution system; means for extracting a fundamental wave component and a harmonic component from the leakage current and the line voltage; and Means for compensating a signal attenuated by an internal filter of the ground fault current detection device when extracting a fundamental wave component and a harmonic component from a line voltage according to the order of the harmonic component; and the leakage current By means of detecting the phase angle with respect to the line voltage and the harmonic component of the leakage current due to the unbalance of the ground capacitance of the distribution system, or by the combination of the harmonic component and the fundamental component of the leakage current , Correcting the unbalance of the leakage current fundamental wave component, correcting the imbalance, and the phase angle of the leakage current fundamental wave component with respect to the line voltage fundamental wave component, And means for calculating the ground fault current using those having a.
本発明によれば、三相配電系統の漏電電流から、絶縁不良によって大地に流れる地絡電流のみを抽出して検出することができる。特に、各相の対地静電容量にアンバランスがある場合でも、このアンバランスを補正した漏電電流及びその位相角を用いて地絡電流を高精度に演算することができる。
更に、地絡電流をスカラー和として求めることにより、従来から用いられている直流絶縁抵抗計と同様に対地絶縁抵抗による地絡電流のスカラー和を求めることとなり、活線状態のままで直流絶縁抵抗計と同様な地絡電流を検出することができる。
加えて、地絡電流を求めるための演算処理も比較的簡単であり、演算負荷が少なくて済む等の効果がある。
According to the present invention, it is possible to extract and detect only the ground fault current flowing to the ground due to insulation failure from the leakage current of the three-phase power distribution system. In particular, even when there is an unbalance in the ground capacitance of each phase, the ground fault current can be calculated with high accuracy using the leakage current and the phase angle corrected for this unbalance.
Furthermore, by obtaining the ground fault current as a scalar sum, the scalar sum of the ground fault current due to the ground insulation resistance is obtained in the same way as a conventional DC insulation resistance meter. A ground fault current similar to the meter can be detected.
In addition, the calculation process for obtaining the ground fault current is relatively simple, and there is an effect that the calculation load can be reduced.
本発明の実施形態に係る絶縁監視装置の構成を示すブロック図である。It is a block diagram which shows the structure of the insulation monitoring apparatus which concerns on embodiment of this invention. 図1において三相配電系統の一相が接地されている場合の系統構成図である。FIG. 2 is a system configuration diagram when one phase of a three-phase power distribution system is grounded in FIG. 1. 実施形態における健全状態の漏電電流と線間電圧との関係を示すベクトル図である。It is a vector diagram which shows the relationship between the earth-leakage current and sound line voltage of the healthy state in embodiment. 実施形態において一相の対地絶縁抵抗が劣化して地絡電流が流れた場合のベクトル図である。FIG. 5 is a vector diagram when a ground fault current flows due to degradation of one-phase ground insulation resistance in the embodiment. 実施形態において一相の対地絶縁抵抗が劣化して地絡電流が流れた場合のベクトル図である。FIG. 5 is a vector diagram when a ground fault current flows due to degradation of one-phase ground insulation resistance in the embodiment. 実施形態において二相の対地絶縁抵抗が劣化して地絡電流が流れた場合のベクトル図である。It is a vector diagram when a ground fault current flows due to deterioration of the two-phase ground insulation resistance in the embodiment. 実施形態における線間電圧及び漏洩電流の第3調波成分を示すベクトル図である。It is a vector diagram which shows the 3rd harmonic component of the line voltage and leakage current in embodiment. 実施形態において、第3調波成分を利用して対地静電容量のアンバランス補正を行う方法を説明するためのベクトル図である。In embodiment, it is a vector diagram for demonstrating the method of performing the unbalance correction of a ground electrostatic capacitance using a 3rd harmonic component. 実施形態において、第5調波成分を利用して対地静電容量のアンバランス補正を行う方法を説明するためのベクトル図である。In embodiment, it is a vector diagram for demonstrating the method of performing the unbalance correction of a ground electrostatic capacitance using a 5th harmonic component. 実施形態において、第5調波成分を利用して対地静電容量のアンバランス補正を行う方法を説明するためのベクトル図である。In embodiment, it is a vector diagram for demonstrating the method of performing the unbalance correction of a ground electrostatic capacitance using a 5th harmonic component. 実施形態において、第7調波成分を利用して対地静電容量のアンバランス補正を行う方法を説明するためのベクトル図である。In embodiment, it is a vector diagram for demonstrating the method of performing the unbalance correction of a ground electrostatic capacitance using a 7th harmonic component.
以下、図に沿って本発明の実施形態を説明する。
図1は、本発明の地絡電流検出方法及び検出装置を絶縁監視装置100に適用した場合の構成図である。図1において、2は三相デルタ結線の交流電源3を有する三相配電系統であり、絶縁監視装置100は、配電系統2の対地絶縁抵抗の劣化により大地に流れる地絡電流を検出するためのものである。
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram when the ground fault current detection method and detection device of the present invention are applied to an insulation monitoring device 100. In FIG. 1, reference numeral 2 denotes a three-phase power distribution system having a three-phase delta-connected AC power supply 3, and the insulation monitoring device 100 detects a ground fault current flowing to the ground due to deterioration of the ground insulation resistance of the power distribution system 2. Is.
配電系統2の線間電圧は絶縁監視装置100内の電圧検出手段10Vに入力されていると共に、零相変流器(ZCT)4により検出された配電系統2の漏電電流が電流検出手段10Iに入力されている。前述したごとく、漏電電流は漏洩電流と地絡電流とのベクトル和である。なお、零相変流器4の代わりに、交流電源3に接続された変圧器(図示せず)の接地線に通常の電流変流器(CT)を接続して漏電電流を検出しても良い。
電圧検出手段10Vは配電系統2の線間電圧を基準電圧として検出し、また、電流検出手段10Iは配電系統2を流れる漏電電流(零相電流)Iを検出するためのものであり、線間電圧及び漏電電流は、何れも系統電圧の基本波成分以外に高調波成分を含んでいるものとする。
The line voltage of the distribution system 2 is input to the voltage detection means 10V in the insulation monitoring device 100, and the leakage current of the distribution system 2 detected by the zero phase current transformer (ZCT) 4 is supplied to the current detection means 10I. Have been entered. As described above, the leakage current is a vector sum of the leakage current and the ground fault current. Instead of the zero-phase current transformer 4, a current leakage current can be detected by connecting a normal current transformer (CT) to the ground line of a transformer (not shown) connected to the AC power source 3. good.
The voltage detection means 10V detects the line voltage of the distribution system 2 as a reference voltage, and the current detection means 10I is for detecting a leakage current (zero-phase current) I 0 flowing through the distribution system 2, It is assumed that the inter-voltage and the leakage current both include harmonic components in addition to the fundamental component of the system voltage.
レベル変換手段20Vは、検出した線間電圧を後続の電子回路により処理可能な電圧レベルに変換し、また、増幅手段20Iは、同じく零相変流器4の二次電流を電子回路により処理可能な電圧レベルに変換するためのものである。
レベル変換手段20V及び増幅手段20Iの各アナログ出力電圧は、A/D変換手段30V,30Iにおいてそれぞれ一定周期でサンプリングされ、ディジタルデータに変換されてRAM等のメモリ40V,40Iにそれぞれ記憶される。メモリ40V,40Iに記憶される電圧データ、電流データの数としては、後述するフーリエ変換処理に十分な数、例えば系統電圧の1周期について32個、64個等が考えられるが、特に限定されるものではない。
The level conversion means 20V converts the detected line voltage into a voltage level that can be processed by the subsequent electronic circuit, and the amplification means 20I can also process the secondary current of the zero-phase current transformer 4 by the electronic circuit. It is for converting to a different voltage level.
The analog output voltages of the level converting means 20V and the amplifying means 20I are sampled at fixed periods by the A / D converting means 30V and 30I, converted into digital data, and stored in the memories 40V and 40I such as RAM. The number of voltage data and current data stored in the memories 40V and 40I may be a number sufficient for Fourier transform processing described later, for example, 32 or 64 for one period of the system voltage, but is particularly limited. It is not a thing.
また、50は演算処理手段としてのCPUであり、前記メモリ40V,40Iにそれぞれ記憶された電圧データ、電流データを用いて、以下の各手段が所定のプログラムに従って演算処理を実行するものである。   Reference numeral 50 denotes a CPU as arithmetic processing means, which uses the voltage data and current data respectively stored in the memories 40V and 40I to execute arithmetic processing according to a predetermined program.
まず、フーリエ変換手段51Vは、メモリ40V内の所定時間窓の電圧データを用いてフーリエ変換を行い、系統電圧の基本波成分及び高調波成分の振幅V及び絶対位相θVn(n=1,3,5,7,・・・)を演算する。ここで、n=1は基本波成分を示し、n=3,5,7,・・・は各次の高調波成分を示す(以下、同じ)。
また、フーリエ変換手段51Iは、メモリ40I内の所定時間窓の電流データを用いてフーリエ変換を行い、上記と同様の原理に従って漏電電流Iの基本波成分及び高調波成分の振幅I0n及び絶対位相θIn(n=1,3,5,7,・・・)を演算する。
上記フーリエ変換には、例えば離散フーリエ変換(DFT)または高速フーリエ変換(FFT)の何れを用いても良い。このようにフーリエ変換によって電圧や電流の基本波成分及び高調波成分の振幅及び絶対位相を求める技術は、例えば特開2004−198273号公報や特許第3599157号公報に記載されている如く周知であるため、ここでは詳述を省略する。
First, the Fourier transform means 51V performs Fourier transform using voltage data of a predetermined time window in the memory 40V, and the amplitude V n and the absolute phase θ Vn (n = 1, 1) of the fundamental wave component and the harmonic component of the system voltage. 3, 5, 7, ...). Here, n = 1 indicates the fundamental wave component, and n = 3, 5, 7,... Indicates the respective harmonic components (hereinafter the same).
Further, the Fourier transform means 51I performs Fourier transform using the current data of a predetermined time window in the memory 40I, and according to the same principle as described above, the amplitude I 0n and the absolute value of the fundamental wave component and the harmonic component of the leakage current I 0 The phase θ In (n = 1, 3, 5, 7,...) Is calculated.
For the Fourier transform, for example, either discrete Fourier transform (DFT) or fast Fourier transform (FFT) may be used. Techniques for obtaining the amplitude and absolute phase of fundamental and harmonic components of voltage and current by Fourier transform in this way are well known as described in, for example, Japanese Patent Application Laid-Open No. 2004-198273 and Japanese Patent No. 3599157. Therefore, detailed description is omitted here.
次に、相対位相演算手段52は、電圧、電流の絶対位相θVn,θInを用いて、θ=θIn−θVnの演算により、線間電圧を基準とした漏電電流Iの相対位相、つまり位相角θを求める。 Next, the relative phase calculation means 52 uses the absolute phases θ Vn and θ In of the voltage and current to calculate the relative phase of the leakage current I 0 based on the line voltage by calculating θ = θ In −θ Vn. That is, the phase angle θ is obtained.
そして、地絡電流演算手段54は、配電系統2の対地静電容量(後述するように非接地二相の対地静電容量)がバランスしている場合には、前記V,I0n及びθを用いて、配電系統2の対地絶縁抵抗による地絡電流l0rを求める。
また、配電系統2の対地静電容量にアンバランスがある場合には、前記V,I0n及びθを用いて、漏電電流Iの基本波成分に対して上記アンバランス分を補正し、対地静電容量がバランスした状態に補正した漏電電流Iの基本波成分の大きさと、線間電圧基本波成分に対する位相角とを用いて、対地絶縁抵抗の劣化による地絡電流l0rをスカラー和として求める。そして、この地絡電流l0rは出力手段60に送られる。
なお、これらの地絡電流l0rの詳細な演算方法については、後に詳述する。
Then, when the ground capacitance of the power distribution system 2 (ungrounded two-phase ground capacitance as will be described later) is balanced, the ground fault current calculating means 54 is configured such that the V n , I 0n and θ Is used to determine the ground fault current 10r due to the ground insulation resistance of the distribution system 2.
When the ground capacitance of the distribution system 2 is unbalanced, the unbalanced part is corrected with respect to the fundamental component of the leakage current I 0 using the V n , I 0n and θ, Using the magnitude of the fundamental wave component of the leakage current I 0 corrected to balance the ground capacitance and the phase angle with respect to the line voltage fundamental wave component, the ground fault current l 0r due to the degradation of the ground insulation resistance is scalarized . Find as sum. The ground fault current 10r is sent to the output means 60.
The detailed calculation method of these ground fault currents 10r will be described in detail later.
漏電電流演算手段53は、前記メモリ40Iに記憶された電流データに基づき、従来から低圧配電設備に用いられている漏電遮断器等と同一の原理により漏電電流Iの実効値を演算し、前記地絡電流l0rと共に出力手段60に送る。
出力手段60は、入力された地絡電流I0r及び漏電電流Iに基づき、表示出力や警報出力、上位装置への伝送出力等を行うものである。
Based on the current data stored in the memory 40I, the leakage current calculation means 53 calculates an effective value of the leakage current I 0 based on the same principle as that of a leakage breaker conventionally used in a low voltage distribution facility, It is sent to the output means 60 together with the ground fault current 10r .
The output means 60 performs display output, alarm output, transmission output to a host device, and the like based on the input ground fault current I 0r and leakage current I 0 .
ここで、図2は、前記配電系統2の一相(一例としてs相)が接地されている場合の系統構成図であり、絶縁監視装置100にはr相、s相間の線間電圧Vrsが基準電圧として入力されているものとする。
図2において、C,Cはそれぞれ非接地相であるr相,t相と大地間の対地静電容量であり、対地静電容量がバランスしている場合にはC=Cである。また、R,Rはそれぞれr相,t相と大地との間の絶縁抵抗(対地絶縁抵抗)を示す。
Here, FIG. 2 is a system configuration diagram in the case where one phase of the power distribution system 2 (for example, the s phase) is grounded, and the insulation monitoring apparatus 100 includes the line voltage V rs between the r phase and the s phase. Is input as a reference voltage.
In FIG. 2, C 1 and C 2 are the ground capacitances between the r-phase and t-phase, which are non-grounded phases, and the ground, respectively, and when the ground capacitances are balanced, C 1 = C 2 is there. R 1 and R 2 indicate the insulation resistance (ground insulation resistance) between the r phase, the t phase, and the ground, respectively.
上記前提のもとで、配電系統2の漏電電流Iから地絡電流I0rを求める手順を以下に説明する。
なお、本実施形態では、地絡電流I0rを、前述の特許文献1,特許文献2等に記載されているようなベクトル合成による電流絶対値でなく、スカラー量(スカラー和)として得るようにしている。すなわち、配電系統の絶縁測定を行う従来の直流絶縁抵抗計では、各線路の対地絶縁抵抗を介して大地に流れる電流のスカラー和から絶縁抵抗を求めているため、本実施形態によれば、CPU50内の地絡電流演算手段54において従来の直流絶縁抵抗計と同一の演算処理により地絡電流(言い換えれば絶縁抵抗)を演算することができると共に、活線状態のままで常時、絶縁監視を行うことを可能にしている。
The procedure for obtaining the ground fault current I 0r from the leakage current I 0 of the distribution system 2 under the above assumption will be described below.
In the present embodiment, the ground fault current I 0r is obtained as a scalar quantity (scalar sum) instead of the current absolute value by vector synthesis as described in Patent Document 1, Patent Document 2, and the like described above. ing. That is, in the conventional DC insulation resistance meter that performs insulation measurement of the distribution system, since the insulation resistance is obtained from the scalar sum of the currents flowing to the ground via the ground insulation resistance of each line, according to the present embodiment, the CPU 50 The ground fault current calculation means 54 can calculate the ground fault current (in other words, the insulation resistance) by the same calculation process as that of the conventional DC insulation resistance meter, and always performs insulation monitoring in the live line state. Making it possible.
次に、図3は、対地絶縁抵抗R,Rが何れも極めて大きい場合、すなわち健全状態における漏電電流及び線間電圧(何れも基本波成分)の関係を示すベクトル図である。この場合、漏電電流Iは対地静電容量に起因する漏洩電流I0cのみであり、地絡電流I0rは零である。つまり、漏洩電流I0cと地絡電流I0rとのベクトル和である漏電電流Iは漏洩電流I0cに等しい(I=I0c)。なお、漏洩電流I0cは、対地静電容量C,Cに流れる電流I0c1,I0c2のベクトル和となる。 Next, FIG. 3 is a vector diagram showing the relationship between the leakage current and the line voltage (both fundamental wave components) when the ground insulation resistances R 1 and R 2 are both extremely large, that is, in a healthy state. In this case, the leakage current I 0 is only the leakage current I 0c resulting from the ground capacitance, and the ground fault current I 0r is zero. That is, the leakage current I 0 that is the vector sum of the leakage current I 0c and the ground fault current I 0r is equal to the leakage current I 0c (I 0 = I 0c ). The leakage current I 0c is the vector sum of the currents I 0c1 and I 0c2 flowing through the ground capacitances C 1 and C 2 .
また、漏洩電流I0cの位相角θは、線間電圧Vrsを基準としたときに120°の進み位相で一定である。漏電電流I(すなわち漏洩電流I0c)の大きさと線間電圧Vrsに対する位相角θとを前述のフーリエ級数演算及び相対位相演算により求め、地絡電流演算手段54が下記の数式1により地絡電流I0rを求めると、その値は前述のごとく零となる。
[数式1]
0r=I×cos(θ−30°)×k=I0c×cos(120°−30°)×k=0
なお、kは、以下に述べるように、対地絶縁抵抗の劣化に起因して流れる地絡電流に応じた定数である。
Further, the phase angle θ c of the leakage current I 0c is constant at a leading phase of 120 ° when the line voltage V rs is used as a reference. The magnitude of the leakage current I 0 (that is, the leakage current I 0c ) and the phase angle θ c with respect to the line voltage V rs are obtained by the Fourier series calculation and the relative phase calculation, and the ground fault current calculation means 54 is calculated by the following formula 1. When the ground fault current I 0r is obtained, the value becomes zero as described above.
[Formula 1]
I 0r = I 0 × cos (θ−30 °) × k = I 0c × cos (120 ° −30 °) × k = 0
Note that k is a constant corresponding to the ground fault current that flows due to the deterioration of the ground insulation resistance, as described below.
次に、図4は、図2におけるr相の対地絶縁抵抗Rが劣化して減少し、地絡電流I0rが流れた場合のベクトル図である。
漏電電流Iは、図4に示すように漏洩電流I0cと地絡電流I0rとのベクトル合成値となり、漏電電流Iの線間電圧Vrsに対する位相角はθとなる。また、漏洩電流I0cの位相角は、図3と同様に線間電圧Vrsを基準にすると120°の進み位相になる。
Next, FIG. 4 is a vector diagram when the r-phase ground insulation resistance R 1 in FIG. 2 deteriorates and decreases, and a ground fault current I 0r flows.
Leakage current I 0 becomes a vector resultant value of the leakage current I 0c and ground fault current I 0r 4, the phase angle for the line voltage V rs of the leakage current I 0 becomes theta. Further, the phase angle of the leakage current I 0c becomes a leading phase of 120 ° with reference to the line voltage V rs as in FIG.
ここで、図4によれば、数式2、数式3が成立する。
[数式2]
0r’=I×cos(θ−30°)
[数式3]
0r’=I0r×cos(30°)=I0r×√3/2
よって、上記数式2、数式3から数式4が導かれる。
[数式4]
0r=I×cos(θ−30°)×2/√3=I×cos(θ−30°)×k
(k=2/√3)
Here, according to FIG. 4, Formula 2 and Formula 3 are established.
[Formula 2]
I 0r '= I 0 × cos (θ-30 °)
[Formula 3]
I 0r ′ = I 0r × cos (30 °) = I 0r × √3 / 2
Therefore, Equation 4 is derived from Equation 2 and Equation 3 above.
[Formula 4]
I 0r = I 0 × cos (θ−30 °) × 2 / √3 = I 0 × cos (θ−30 °) × k
(K = 2 / √3)
数式4から明らかなように、r相の対地絶縁抵抗Rが劣化して地絡電流I0rが流れた場合でも、地絡電流演算手段54は、数式1と同様の数式4の演算を行うことにより、漏洩電流I0cの影響を受けずに、実質的に漏洩電流I0cを除去した形で地絡電流I0rを抽出することができる。 As apparent from Equation 4, even when the r-phase ground insulation resistance R 1 deteriorates and the ground fault current I 0r flows, the ground fault current calculation means 54 performs the calculation of Equation 4 similar to Equation 1. As a result, the ground fault current I 0r can be extracted in a form in which the leakage current I 0c is substantially removed without being affected by the leakage current I 0c .
図5は、t相の対地絶縁抵抗Rが低下し、地絡電流I0rが流れた場合のベクトル図である。
この場合も、漏電電流Iは漏洩電流I0cと地絡電流I0rとのベクトル合成値となり、漏電電流Iの線間電圧Vrsに対する位相角はθとなる。また、対地静電容量に起因する漏洩電流I0cは、前記同様に線間電圧Vrsに対して120°の進み位相となる。
5, reduces the ground insulation resistance R 2 of the t-phase is a vector diagram when the ground fault current I 0r flows.
Also in this case, the leakage current I 0 is a vector composite value of the leakage current I 0c and the ground fault current I 0r, and the phase angle of the leakage current I 0 with respect to the line voltage V rs is θ. Further, the leakage current I 0c caused by the ground capacitance has a leading phase of 120 ° with respect to the line voltage V rs as described above.
更に、図5においても、数式2、数式3と同様に数式5、数式6が成立する。
[数式5]
0r’=I×cos(θ−30°)
[数式6]
0r’=I0r×cos(30°)=I0r×√3/2
従って、上記数式5、数式6から数式7が導かれる。
[数式7]
0r=I×cos(θ−30°)×2/√3=I×cos(θ−30°)×k
(k=2/√3)
Further, in FIG. 5, similarly to Equations 2 and 3, Equations 5 and 6 are established.
[Formula 5]
I 0r '= I 0 × cos (θ-30 °)
[Formula 6]
I 0r ′ = I 0r × cos (30 °) = I 0r × √3 / 2
Therefore, Equation 7 is derived from Equation 5 and Equation 6 above.
[Formula 7]
I 0r = I 0 × cos (θ−30 °) × 2 / √3 = I 0 × cos (θ−30 °) × k
(K = 2 / √3)
よって、t相の絶縁抵抗Rが劣化して地絡電流I0rが流れた場合でも、地絡電流演算手段54は、数式1と同様の数式7の演算により、漏洩電流I0cの影響を受けずにこれを除去した形で地絡電流I0rを検出することができる。 Therefore, even when the t-phase insulation resistance R 2 deteriorates and the ground fault current I 0r flows, the ground fault current calculation means 54 determines the influence of the leakage current I 0c by the calculation of Formula 7 similar to Formula 1. The ground fault current I 0r can be detected in such a manner that it is removed without receiving it.
図6は、r相及びt相の双方の対地絶縁抵抗R,Rが劣化し、地絡電流I0r1,I0r2が流れた場合のベクトル図である。なお、I0r1とI0r2をベクトル合成した地絡電流をI0r”として示してある。
この場合も、漏電電流Iは漏洩電流I0cと地絡電流I0r”との合成値であり、漏電電流Iの線間電圧Vrsに対する位相角はθとなる。また、対地静電容量に起因する漏洩電流I0cは、前記同様に線間電圧Vrsに対して120°の進み位相となる。
FIG. 6 is a vector diagram when the ground insulation resistances R 1 and R 2 of both the r-phase and the t-phase are deteriorated and the ground fault currents I 0r1 and I 0r2 flow. The ground fault current obtained by vector synthesis of I 0r1 and I 0r2 is shown as I 0r ″.
Also in this case, the leakage current I 0 is a composite value of the leakage current I 0c and the ground fault current I 0r ″, and the phase angle of the leakage current I 0 with respect to the line voltage V rs is θ. The leakage current I 0c resulting from the capacitance has a leading phase of 120 ° with respect to the line voltage V rs as described above.
図6において、数式2、数式5と同様に数式8が成立する。
[数式8]
0r’=I×cos(θ−30°)
また、求める地絡電流I0rの大きさは、I0r1とI0r2とのスカラー和である。ここで、図6において、Δabcは各内角が60°の正三角形であるから、線分ab,bcの長さは等しく、地絡電流I0r2の大きさは線分ab(=bc)の長さに等しいと共に、地絡電流I0r1の大きさは線分0bの長さに等しい。従って、図6における0c(=0b+bc)は地絡電流I0rの大きさに等しいため、I0r’に関して数式9が成立する。
[数式9]
0r’=0c×cos(30°)=I0r×cos(30°)=I0r×√3/2
In FIG. 6, Expression 8 is established similarly to Expression 2 and Expression 5.
[Formula 8]
I 0r '= I 0 × cos (θ-30 °)
The magnitude of the ground fault current I 0r to be obtained is a scalar sum of I 0r1 and I 0r2 . Here, in FIG. 6, Δabc is an equilateral triangle having an inner angle of 60 °, so the lengths of the line segments ab and bc are equal, and the magnitude of the ground fault current I 0r2 is the length of the line segment ab (= bc). And the magnitude of the ground fault current I 0r1 is equal to the length of the line segment 0b. Therefore, since 0c (= 0b + bc) in FIG. 6 is equal to the magnitude of the ground fault current I 0r , Equation 9 is established for I 0r ′.
[Formula 9]
I 0r '= 0c × cos (30 °) = I 0r × cos (30 °) = I 0r × √3 / 2
数式8、数式9より、下記のように、前記数式1、数式4、数式7と同一の数式10が導かれる。
[数式10]
0r=I×cos(θ−30°)×2/√3=I×cos(θ−30°)×k
(k=2/√3)
以上の数式1、数式4、数式7、数式10が同一の演算式になることから分かるように、配電系統2の対地静電容量(非接地であるr相、t相の対地静電容量C,C)がバランスしている状態では、r相及びt相の対地絶縁抵抗に起因する地絡電流I0r1,I0r2がそれぞれいかなる値になったとしても、地絡電流演算手段54は、図1のフーリエ変換手段51I及び相対位相演算手段52から出力される漏電電流Iとその位相角θとに基づき、地絡電流I0rの大きさを、スカラー量(スカラー和)として同一の演算アルゴリズムにより理論上の誤差なく求めることができる。
From Equation 8 and Equation 9, Equation 10 that is the same as Equation 1, Equation 4, and Equation 7 is derived as follows.
[Formula 10]
I 0r = I 0 × cos (θ−30 °) × 2 / √3 = I 0 × cos (θ−30 °) × k
(K = 2 / √3)
As can be understood from the above formulas 1, 4, 7, and 10 being the same calculation formula, the ground capacitance of the distribution system 2 (the ungrounded r-phase and t-phase ground capacitances C) 1 , C 2 ) are balanced, no matter what the values of the ground fault currents I 0r1 , I 0r2 due to the ground insulation resistances of the r-phase and t-phase are, The magnitude of the ground fault current I 0r is the same as the scalar quantity (scalar sum) based on the leakage current I 0 and the phase angle θ output from the Fourier transform means 51I and the relative phase calculation means 52 in FIG. The calculation algorithm can be used without any theoretical error.
以上のように、配電系統2の対地静電容量がバランスしている場合に漏電電流I及びその位相角θから地絡電流I0rを求めることが可能であるが、対地静電容量がアンバランスであっても、そのアンバランス分を補正した漏電電流I’とその位相角とを求めることができれば、上記と同様の手順により地絡電流I0rの大きさをスカラー量として求めることができる。
以下では、非接地であるr相、t相の対地静電容量C,Cがアンバランスであるときの漏洩電流I0cから、上記のアンバランス分を補正した漏電電流I’ とその位相角とを求め、これらに基づいて地絡電流I0rの大きさを演算する方法を説明する。
As described above, when the ground capacitance of the distribution system 2 is balanced, the ground fault current I 0r can be obtained from the leakage current I 0 and the phase angle θ. Even in the case of balance, if the leakage current I 0 ′ corrected for the unbalance and the phase angle can be obtained , the magnitude of the ground fault current I 0r can be obtained as a scalar quantity by the same procedure as described above. it can.
In the following description, the leakage current I 0 ′ obtained by correcting the above-mentioned imbalance from the leakage current I 0c when the ungrounded r-phase and t-phase ground capacitances C 1 and C 2 are unbalanced and its leakage current I 0 ′ A method of obtaining the phase angle and calculating the magnitude of the ground fault current I 0r based on these will be described.
なお、対地静電容量のアンバランスは漏洩電流I0cに影響を及ぼし、ひいては漏電電流Iの大きさ及び位相角に影響するので、地絡電流I0rを高精度に検出するためには、上記アンバランスを補正した漏電電流I’を求めて地絡電流I0rを演算することが必要であり、以下の説明はこのような原理に基づくものである。また、以下では、線間電圧、漏電電流に含まれる高調波成分に着目したアンバランス補正値を用いて漏電電流Iの基本波成分を補正することにより、漏電電流I’を求めている。 In addition, since the unbalance of the ground capacitance affects the leakage current I 0c and thus affects the magnitude and phase angle of the leakage current I 0 , in order to detect the ground fault current I 0r with high accuracy, It is necessary to calculate the ground fault current I 0r by obtaining the leakage current I 0 ′ corrected for the unbalance, and the following explanation is based on such a principle. In the following, the leakage current I 0 ′ is obtained by correcting the fundamental wave component of the leakage current I 0 using the unbalance correction value focusing on the harmonic component included in the line voltage and leakage current. .
図7、図8は、アンバランス補正値を求めるための高調波成分として、第3調波成分を用いる場合のベクトル図である。
まず、図7は、線間電圧(第3調波)、及び、対地静電容量に起因した漏洩電流(第3調波)のベクトル図である。図7に示すように、線間電圧(第3調波)Vrs,Vtsの相互の位相角は180°となる。これは、図3では線間電圧Vrs,Vtsの基本波成分相互の位相角は60°であったが、基本波成分の位相角に相当する位相時間は第3調波では3倍になるため、線間電圧(第3調波)Vrs,Vtsの相互の位相角は60°の3倍、つまり180°となるためである。
7 and 8 are vector diagrams in the case where the third harmonic component is used as the harmonic component for obtaining the unbalance correction value.
First, FIG. 7 is a vector diagram of the line voltage (third harmonic) and the leakage current (third harmonic) due to the ground capacitance. As shown in FIG. 7, the mutual phase angle of the line voltages (third harmonics) V rs and V ts is 180 °. In FIG. 3, the phase angle between the fundamental wave components of the line voltages V rs and V ts is 60 °, but the phase time corresponding to the phase angle of the fundamental wave component is tripled in the third harmonic. Therefore , the mutual phase angle of the line voltages (third harmonics) V rs and V ts is three times 60 °, that is, 180 °.
上記のごとく、線間電圧(第3調波)Vrs,Vtsの相互の位相角は180°になるため、r相,t相の対地静電容量に起因する漏洩電流(第3調波)I0c1,I0c2は、線間電圧(第3調波)Vrsを基準にすると、図7に示すごとく各々90°の進み位相、270°の進み位相となる。つまり、漏洩電流(第3調波)I0c1,I0c2は180°位相がずれた逆方向の電流となり、これらが合成された漏洩電流(第3調波)I0cは漏洩電流(第3調波)I0c1,I0c2の差になっている。 As described above, since the mutual phase angle of the line voltages (third harmonics) V rs and V ts is 180 °, the leakage current (third harmonic) caused by the r-phase and t-phase ground capacitances. ) I 0c1 and I 0c2 have a leading phase of 90 ° and a leading phase of 270 °, respectively, as shown in FIG. 7, with reference to the line voltage (third harmonic) V rs . That is, the leakage currents (third harmonics) I 0c1 and I 0c2 are currents in the opposite directions that are 180 ° out of phase, and the combined leakage current (third harmonic) I 0c is the leakage current (third harmonics). Wave) The difference between I 0c1 and I 0c2 .
図8は、漏電電流Iの基本波成分を、上述した漏洩電流(第3調波)I0cを用いて補正する方法を説明するためのものである。
前述したように、図7により、対地静電容量のアンバランスに起因する漏洩電流(第3調波)I0cを求めることができる。この漏洩電流(第3調波)I0cを漏電電流Iの基本波成分のアンバランス分に換算したアンバランス補正値I0c’を用いて、漏電電流Iの基本波成分を補正することにより、対地静電容量がバランスしたときの漏電電流I’を求めることができる。
FIG. 8 is a diagram for explaining a method of correcting the fundamental wave component of the leakage current I 0 using the leakage current (third harmonic) I 0c described above.
As described above, the leakage current (third harmonic) I 0c resulting from the unbalance of the capacitance to the ground can be obtained from FIG. Using the unbalance correction value I 0c ′ obtained by converting this leakage current (third harmonic) I 0c into an unbalanced component of the fundamental wave component of the leakage current I 0 , the fundamental wave component of the leakage current I 0 is corrected. Thus, the leakage current I 0 ′ when the ground capacitance is balanced can be obtained.
ここで、対地静電容量に起因する漏洩電流の大きさは周波数に比例するから、電圧が同一の場合には、漏洩電流(第3調波)の大きさは基本波成分の3倍となる。このことは、線間電圧の第3調波成分の大きさが基本波成分の1/3のときに、漏洩電流(第3調波)の大きさが基本波成分の大きさに等しくなることを意味している。
よって、漏洩電流(第3調波)I0cを漏電電流Iの基本波成分に換算するには、線間電圧の第3調波成分の大きさを基本波成分の1/3としたときの漏洩電流値をアンバランス補正値I0c’とし、このアンバランス補正値I0c’により漏電電流Iの基本波成分を補正して新たに漏電電流I’を求めれば良い。
すなわち、線間電圧Vrsの基本波成分をVrs1、第3調波成分をVrs3とし、漏洩電流(第3調波)をI0cとすれば、アンバランス補正値I0c’は数式11によって求められる。
[数式11]
0c’=I0c×(1/3)×(Vrs1/Vrs3
Here, since the magnitude of the leakage current caused by the ground capacitance is proportional to the frequency, when the voltage is the same, the magnitude of the leakage current (third harmonic) is three times the fundamental wave component. . This means that when the magnitude of the third harmonic component of the line voltage is 1/3 of the fundamental component, the magnitude of the leakage current (third harmonic) is equal to the magnitude of the fundamental component. Means.
Therefore, in order to convert the leakage current (third harmonic) I 0c into the fundamental wave component of the leakage current I 0 , the magnitude of the third harmonic component of the line voltage is 1/3 of the fundamental wave component. The leakage current value is set to an unbalance correction value I 0c ′, and the fundamental wave component of the leakage current I 0 is corrected by the unbalance correction value I 0c ′ to newly obtain the leakage current I 0 ′.
That is, assuming that the fundamental wave component of the line voltage V rs is V rs1 , the third harmonic component is V rs3 , and the leakage current (third harmonic) is I 0c , the unbalance correction value I 0c ′ is expressed by Equation 11 Sought by.
[Formula 11]
I 0c ′ = I 0c × (1/3) × (V rs1 / V rs3 )
図8に示すように、上記アンバランス補正値I0c’を用いてIを補正する(I0c’をIにベクトル加算する)ことにより、対地静電容量のアンバランス分を補正した漏電電流I’を求めることができる。Iの大きさ及び位相角、並びに、換算値I0c’の大きさ及び位相角は定まっているので、I’の演算は容易であり、その位相角θについても、I’のベクトル座標(x,y)が求まれば数式12により求まることは明白である。
[数式12]
θ=cos−1{x/√(x+y)}
As shown in FIG. 8, by correcting I 0 using the unbalance correction value I 0c ′ (adding I 0c ′ to I 0 as a vector), an earth leakage in which the unbalanced portion of the ground capacitance is corrected is corrected. The current I 0 ′ can be obtained. Since the magnitude and phase angle of I 0 and the magnitude and phase angle of the converted value I 0c ′ are fixed, the calculation of I 0 ′ is easy, and the phase angle θ is also a vector of I 0 ′. If the coordinates (x, y) are obtained, it is obvious that the equation (12) is obtained.
[Formula 12]
θ = cos −1 {x / √ (x 2 + y 2 )}
なお、図7では電流が対地静電容量成分のみを含む例を示したが、対地抵抗成分も含む場合には、漏電電流Iの第3調波成分とその位相角とから、90°の進み位相成分または270°の進み位相成分を演算により求めれば漏洩電流(第3調波)I0cを求めることができ、以後は上記と同様の演算によって漏電電流I’を求めることが可能である。
以上のようにして、対地静電容量がアンバランスである場合にも、そのアンバランスをアンバランス補正値I0c’により補正してI’を求め、このI’及び位相角θを用いて前記数式10等の演算を行えば、地絡電流I0rの大きさをスカラー量として求めることができる。
Note that FIG. 7 shows an example in which the current includes only the ground capacitance component. However, in the case where the current also includes the ground resistance component, 90 ° is obtained from the third harmonic component of the leakage current I 0 and its phase angle. The leakage current (third harmonic) I 0c can be obtained by calculating the leading phase component or the leading phase component of 270 °, and thereafter the leakage current I 0 ′ can be determined by the same calculation as described above. is there.
As described above, even when the ground capacitance is unbalanced, the unbalance is corrected by the unbalance correction value I 0c ′ to obtain I 0 ′, and this I 0 ′ and the phase angle θ are used. Then, if the calculation of Equation 10 or the like is performed , the magnitude of the ground fault current I 0r can be obtained as a scalar quantity.
図9、図10は、アンバランス補正を行うための高調波成分として、第5調波成分を用いる場合のベクトル図である。
線間電圧Vrs,Vtsの第5調波成分の相互の位相角は、Vtsに対しVrsが60°進み位相となる。図3において線間電圧の基本波成分はVrsに対しVtsが60°進み位相であったが、基本波成分の60°位相時間は第5調波では5倍の位相角となり、300°の進み位相となる。これは、Vtsに対してVrsが60°進み位相であることに等しい。
9 and 10 are vector diagrams in the case where the fifth harmonic component is used as the harmonic component for performing the unbalance correction.
The mutual phase angle of the fifth harmonic components of the line voltages V rs and V ts is a phase where V rs is advanced by 60 ° with respect to V ts . In FIG. 3, the fundamental wave component of the line voltage has a phase where V ts is advanced by 60 ° with respect to V rs , but the 60 ° phase time of the fundamental wave component has a phase angle of 5 times in the fifth harmonic and is 300 °. Is the leading phase. This is equivalent to V rs being a 60 ° advance phase with respect to V ts .
図9は、図2においてt相の対地静電容量Cがr相のCより大きい場合における、対地静電容量に起因した漏洩電流の基本波成分のベクトル位相関係を示しており、Vrsを基準としたものである。また、図10は、上記と同一の漏洩電流の第5調波成分のベクトル位相関係を示しており、Vtsを基準としたものである。
これらの図9、図10を比較すると、対地静電容量に起因する漏洩電流の基本波成分及び第5調波成分I0c(I)は、位相角が120°の中心線を基準として対称となっている。このことは、漏洩電流の第5調波成分を漏洩電流の基本波成分に等しい大きさに換算した上で両者をベクトル加算すれば、漏洩電流の位相角は中心線の位相角である120°になることを示している。そしてこの位相角(120°)は、対地静電容量C,Cがバランスしているときの漏洩電流の位相角に等しい。
FIG. 9 shows the vector phase relationship of the fundamental wave component of the leakage current caused by the ground capacitance when the t-phase ground capacitance C 2 is larger than the r-phase C 1 in FIG. It is based on rs . FIG. 10 shows the vector phase relationship of the fifth harmonic component of the same leakage current as described above, which is based on V ts .
Comparing FIG. 9 and FIG. 10, the fundamental wave component and the fifth harmonic component I 0c (I 0 ) of the leakage current caused by the ground capacitance are symmetrical with respect to the center line having a phase angle of 120 °. It has become. This means that if the fifth harmonic component of the leakage current is converted to a magnitude equal to the fundamental wave component of the leakage current and the vectors are added together, the phase angle of the leakage current is 120 ° which is the phase angle of the center line. It shows that it becomes. This phase angle (120 °) is equal to the phase angle of the leakage current when the ground capacitances C 1 and C 2 are balanced.
漏洩電流の第5調波成分を漏洩電流の基本波成分に等しい大きさに換算するには、静電容量に起因する漏洩電流は周波数に比例することから、線間電圧が同一の場合、漏洩電流の第5調波成分は基本波成分の5倍となる。このことは、線間電圧の第5調波成分が基本波成分の1/5であるときに漏洩電流の第5調波成分は基本波成分に等しくなることを示している。よって、線間電圧の第5調波成分を基本波成分の1/5としたときの漏洩電流値をアンバランス補正値I0c’として、漏洩電流の第5調波成分を基本波成分に等しい大きさに換算する。
ここで、線間電圧Vrsの基本波成分をVrs1、第5調波成分をVrs5、漏洩電流の第5調波成分をI0cとすれば、アンバランス補正値I0c’は数式13によって求められる。
[数式13]
0c’=I0c×(1/5)×(Vrs1/Vrs5
In order to convert the fifth harmonic component of the leakage current into the same magnitude as the fundamental component of the leakage current, the leakage current caused by the capacitance is proportional to the frequency. The fifth harmonic component of the current is five times the fundamental component. This indicates that when the fifth harmonic component of the line voltage is 1/5 of the fundamental component, the fifth harmonic component of the leakage current is equal to the fundamental component. Therefore, the leakage current value when the fifth harmonic component of the line voltage is 1/5 of the fundamental wave component is set as the unbalance correction value I 0c ′, and the fifth harmonic component of the leakage current is equal to the fundamental wave component. Convert to size.
Here, if the fundamental wave component of the line voltage V rs is V rs1 , the fifth harmonic component is V rs5 , and the fifth harmonic component of the leakage current is I 0c , the unbalance correction value I 0c ′ is expressed by Equation 13: Sought by.
[Formula 13]
I 0c ′ = I 0c × (1/5) × (V rs1 / V rs5 )
以上より、漏洩電流の基本波成分と数式13によるアンバランス補正値I0c’とをベクトル加算した電流の位相は、図9,図10の中心線の位相角である120°となり、対地静電容量がバランスしたときの漏洩電流の位相角となる。この漏洩電流を漏電電流Iとして用い、前述した対地静電容量がバランスしたときと同様に数式10等の演算を行うことで、地絡電流I0rをスカラー量として求めることができる。
なお、この場合の地絡電流I0rは基本波成分と第5調波成分との和であるため、第5調波成分を除去することにより基本波成分を求める必要がある。
From the above, the phase of the current obtained by vector addition of the fundamental wave component of the leakage current and the unbalance correction value I 0c ′ according to Equation 13 is 120 °, which is the phase angle of the center line in FIGS. This is the phase angle of the leakage current when the capacity is balanced. By using this leakage current as the leakage current I 0 and performing the calculation of Equation 10 and the like in the same manner as when the ground capacitance is balanced, the ground fault current I 0r can be obtained as a scalar quantity.
Since the ground fault current I 0r in this case is the sum of the fundamental wave component and the fifth harmonic component, it is necessary to obtain the fundamental wave component by removing the fifth harmonic component.
図11は、アンバランス補正を行うための高調波成分として、第7調波成分を用いる場合のベクトル図である。
線間電圧Vrs,Vtsの第7調波成分の相互の位相角は、Vrsに対しVtsが60°進み位相となる。図3において線間電圧の基本波成分はVrsに対しVtsが60°進み位相であったが、基本波成分の60°位相時間は第7調波では7倍の位相角となり、420°の進み位相となる。これは、Vrsを基準とした場合に、Vrsに対してVtsが60°進み位相となり、基本波と同一の進みとなる。
FIG. 11 is a vector diagram when the seventh harmonic component is used as the harmonic component for performing the unbalance correction.
The mutual phase angle of the seventh harmonic components of the line voltages V rs and V ts is a phase that V ts advances by 60 ° with respect to V rs . In FIG. 3, the fundamental wave component of the line voltage has a phase where V ts is advanced by 60 ° with respect to V rs , but the 60 ° phase time of the fundamental wave component has a phase angle that is 7 times that of the seventh harmonic, and is 420 ° Is the leading phase. When V rs is used as a reference, V ts advances by 60 ° with respect to V rs , and the same advance as the fundamental wave.
漏洩電流の第7調波成分を漏洩電流の基本波成分に等しい大きさに換算するには、対地静電容量に起因する漏洩電流は周波数に比例することから、線間電圧が同一の場合、漏洩電流の第7調波成分は基本波成分の7倍となる。このことは、線間電圧の第7調波成分が基本波成分の1/7であるときに漏洩電流の第7調波成分は基本波成分に等しくなることを示している。よって、線間電圧の第7調波成分を基本波成分の1/7としたときの漏洩電流値をアンバランス補正値I0c’として、漏洩電流の第7調波成分を基本波成分に等しい大きさに換算する。
すなわち、線間電圧Vrsの基本波成分をVrs1、第7調波成分をVrs7、漏洩電流の第7調波成分をI07とすれば、アンバランス補正値I07’は数式14によって求められる。
[数式14]
07’=I07×(1/7)×(Vrs1/Vrs7
このアンバランス補正値I07’と漏電電流の基本波成分I01とを比較すると、対地静電容量に起因する漏洩電流は等しく、対地絶縁抵抗に起因する地絡電流については、第7調波成分が基本波成分の1/7となる。
In order to convert the seventh harmonic component of the leakage current into a magnitude equal to the fundamental component of the leakage current, since the leakage current due to the ground capacitance is proportional to the frequency, when the line voltage is the same, The seventh harmonic component of the leakage current is seven times the fundamental wave component. This indicates that the seventh harmonic component of the leakage current is equal to the fundamental component when the seventh harmonic component of the line voltage is 1/7 of the fundamental component. Therefore, the leakage current value when the seventh harmonic component of the line voltage is 1/7 of the fundamental wave component is set as the unbalance correction value I 0c ′, and the seventh harmonic component of the leakage current is equal to the fundamental wave component. Convert to size.
That is, if the fundamental component of the line voltage V rs is V rs1 , the seventh harmonic component is V rs7 , and the seventh harmonic component of the leakage current is I 07 , the unbalance correction value I 07 ′ Desired.
[Formula 14]
I 07 ′ = I 07 × (1/7) × (V rs1 / V rs7 )
When this unbalance correction value I 07 ′ is compared with the fundamental wave component I 01 of the leakage current, the leakage current caused by the ground capacitance is equal, and the ground fault current caused by the ground insulation resistance is the seventh harmonic. The component is 1/7 of the fundamental wave component.
ここで、対地静電容量に起因する漏洩電流をI0cとし、I0c,I07’及びI01のベクトルの先端を図11に示すように各々a,b,cとすれば、線分ab,acの長さは対地絶縁抵抗に起因した地絡電流に比例することにより、電圧に比例し、ab:acは1:7となる。この関係とI01,I07’の位置とにより、対地静電容量に起因する漏洩電流I0cのベクトル位置が求められる。これを対地静電容量がバランスしたときの値に補正するためには、I0cの位相角が120°となるようにI0c’を求めれば良い。
漏電電流の基本波成分についても、I01を上記のI0c’により補正すれば、対地静電容量がバランスしたときの漏電電流I’を得ることができる。この漏電電流I’により、前述した対地静電容量がバランスしたときと同様に数式10等の演算を行うことで、地絡電流I0rをスカラー量として求めることができる。
Here, if the leakage current resulting from the ground capacitance is I 0c and the leading ends of the vectors I 0c , I 07 ′ and I 01 are a, b and c as shown in FIG. , Ac is proportional to the voltage by being proportional to the ground fault current caused by the ground insulation resistance, and ab: ac is 1: 7. Based on this relationship and the positions of I 01 and I 07 ′, the vector position of the leakage current I 0c caused by the ground capacitance is obtained. In order to correct this to a value when the ground capacitance is balanced, I 0c ′ may be obtained so that the phase angle of I 0c is 120 °.
Also for the fundamental wave component of the leakage current, if I 01 is corrected by the above I 0c ′, the leakage current I 0 ′ when the ground capacitance is balanced can be obtained. The ground fault current I 0r can be obtained as a scalar quantity by performing the calculation of Equation 10 or the like with the leakage current I 0 ′ in the same manner as when the above-mentioned ground capacitance is balanced.
上記実施形態では、電圧、電流の基本波成分と第3調波成分または第5調波成分または第7調波成分とを組み合わせて地絡電流I0rを求める方法につき説明したが、実際の波形においては、電源や負荷の種類に応じて第3,第5,第7等の各高調波成分の含有率や含有の有無が異なり、必ずしもすべての高調波成分が含有されるとは限らない。
このため、地絡電流検出装置としては、前述した各高調波成分に対する演算機能を図1のCPU50が備えると共に、各高調波成分に対する複数の演算結果の中から最適の地絡電流を唯一決定するような手段を備えることが望ましい。このような手段の例としては、例えば含有率が最も大きい高調波成分に対する演算結果(地絡電流値)を選定する手段や、すべての高調波成分に対する演算結果の平均値を求める手段等が考えられるが、勿論、これらに限定されるものではない。
In the above embodiment, the method of obtaining the ground fault current I 0r by combining the fundamental component of voltage and current with the third harmonic component, the fifth harmonic component or the seventh harmonic component has been described. , The content rate of each harmonic component such as the third, fifth, seventh, etc., and the presence or absence of inclusion differ depending on the type of power supply or load, and not all harmonic components are necessarily contained.
For this reason, as the ground fault current detection device, the CPU 50 of FIG. 1 has the calculation function for each harmonic component described above, and the optimum ground fault current is uniquely determined from a plurality of calculation results for each harmonic component. It is desirable to provide such means. Examples of such means include means for selecting a calculation result (ground fault current value) for a harmonic component having the largest content rate, means for obtaining an average value of calculation results for all harmonic components, and the like. Of course, the present invention is not limited to these.
また、本実施形態では、上述のように第3調波成分または第5調波成分または第7調波成分を用いているが、これら以外の高調波成分を用いて対地静電容量のアンバランスを補正しても良いのは言うまでもない。
更に、電子機器においては、目的とする信号以外に高周波ノイズ信号が混入することが考えられ、その対策として、例えば図1における電圧検出手段10Vや電流検出手段10I等の入力部に、抵抗及びコンデンサからなるR−Cフィルタ等を付加することが多い。この場合、基本波成分に対して高次高調波成分ほど信号の減衰が大きくなるが、その減衰割合は周波数に応じて常に一定値となる。
このことから、電子機器の内部フィルタによる信号の減衰分を各高調波に応じた補正係数にて補償すれば、元の信号に含有された各高調波成分を正確に再現することができ、最終的な地絡電流の演算精度を一層向上させることができる。
In the present embodiment, as described above, the third harmonic component, the fifth harmonic component, or the seventh harmonic component is used. However, the unbalanced capacitance of the ground using other harmonic components. Needless to say, it may be corrected.
Further, in an electronic device, it is conceivable that a high frequency noise signal is mixed in addition to a target signal. As a countermeasure, for example, a resistor and a capacitor are connected to the input unit such as the voltage detection unit 10V and the current detection unit 10I in FIG. In many cases, an R-C filter or the like is added. In this case, the higher-order harmonic component relative to the fundamental wave component, the greater the signal attenuation, but the attenuation ratio is always a constant value depending on the frequency.
Therefore, if the attenuation of the signal by the internal filter of the electronic device is compensated with a correction coefficient corresponding to each harmonic, each harmonic component contained in the original signal can be accurately reproduced, and finally It is possible to further improve the calculation accuracy of the ground fault current.
上述した実施形態は本発明を絶縁監視装置100に適用した場合のものであるが、本発明は、回路遮断器、漏電遮断器、または漏電リレー、もしくはこれらと指示計器類を組合せた機器にも適用可能である。   The above-described embodiment is the case where the present invention is applied to the insulation monitoring device 100. However, the present invention is also applicable to a circuit breaker, a leakage breaker, or a leakage relay, or a device that combines these and indicator instruments. Applicable.
2:三相配電系統
3:交流電源
4:零相変流器
10V:電圧検出手段
10I:電流検出手段
20V:レベル変換手段
20I:増幅手段
30V,30I:A/D変換手段
40V,40I:メモリ
50:CPU
51V,51I:フーリエ変換手段
52:相対位相演算手段
53:漏電電流演算手段
54:地絡電流演算手段
60:出力手段
100:絶縁監視装置
2: Three-phase power distribution system 3: AC power supply 4: Zero-phase current transformer 10V: Voltage detection means 10I: Current detection means 20V: Level conversion means 20I: Amplification means 30V, 30I: A / D conversion means 40V, 40I: Memory 50: CPU
51V, 51I: Fourier transform means 52: Relative phase calculation means 53: Leakage current calculation means 54: Ground fault current calculation means 60: Output means 100: Insulation monitoring device

Claims (3)

  1. 三相デルタ結線の交流電源を有し、かつ一相が接地された三相配電系統を対象として、前記配電系統の漏電電流と、前記漏電電流の線間電圧に対する位相角とを用いて、前記配電系統の対地絶縁抵抗に起因した地絡電流を検出する地絡電流検出方法において、
    前記配電系統の対地静電容量のアンバランスに起因する漏洩電流の高調波成分により、または、漏洩電流の高調波成分及び基本波成分の組み合わせにより、漏電電流基本波成分のアンバランスを補正する手段であって、前記高調波成分が第n(nは3以上の奇数)調波成分であるときに、線間電圧の第n調波成分を線間電圧の基本波成分の1/nとしたときの前記漏洩電流の第n調波成分の値を用いて前記漏電電流基本波成分のアンバランスを補正する手段を備え、
    前記アンバランスを補正した漏電電流基本波成分とこの漏電電流基本波成分の線間電圧基本波成分に対する位相角とを用いて地絡電流を演算する処理を、複数種類の第n調波成分につき実行して複数の地絡電流を求め、そのうちの一つを選択することを特徴とする地絡電流検出方法。
    For a three-phase power distribution system having a three-phase delta-connected AC power source and one phase grounded, using the leakage current of the distribution system and the phase angle of the leakage current with respect to the line voltage, In the ground fault current detection method for detecting the ground fault current due to the ground insulation resistance of the distribution system,
    Means for correcting the unbalance of the leakage current fundamental wave component by the harmonic component of the leakage current caused by the unbalance of the electrostatic capacitance to the ground of the distribution system or by the combination of the harmonic component and the fundamental wave component of the leakage current When the harmonic component is the nth (n is an odd number of 3 or more) harmonic component, the nth harmonic component of the line voltage is set to 1 / n of the fundamental wave component of the line voltage. Means for correcting an unbalance of the leakage current fundamental wave component using a value of the nth harmonic component of the leakage current when
    The process of calculating the ground fault current with the phase angle for the line voltage fundamental component of the leakage current fundamental wave component of the leakage current fundamental component Toko obtained by correcting the imbalance, per a plurality of types of the n harmonic components A ground fault current detection method comprising: executing a plurality of ground fault currents and selecting one of them .
  2. 請求項1に記載した地絡電流検出方法において、
    前記三相配電系統のうちの非接地二相の対地絶縁抵抗による地絡電流のスカラー和を演算することを特徴とする地絡電流検出方法。
    In the ground fault current detection method according to claim 1,
    Ground fault current detecting method characterized that you calculating the scalar sum of the ground fault current due to ground insulation resistance of an ungrounded two phases of the three-phase power distribution system.
  3. 三相デルタ結線の交流電源を有し、かつ一相が接地された三相配電系統を対象として、前記配電系統の漏電電流と、前記漏電電流の線間電圧に対する位相角とを用いて、前記配電系統の対地絶縁抵抗による地絡電流を演算する地絡電流検出装置において、
    前記配電系統の漏電電流を検出する手段と、
    前記配電系統の線間電圧を検出する手段と、
    前記漏電電流及び線間電圧から基本波成分及び高調波成分を抽出する手段と、
    前記漏電電流及び線間電圧から基本波成分及び高調波成分を抽出する際に前記地絡電流検出装置の内部フィルタにより減衰した信号を、前記高調波成分の次数に応じて補償する手段と、
    前記漏電電流の前記線間電圧に対する位相角を検出する手段と、
    前記配電系統の対地静電容量のアンバランスに起因する前記漏洩電流の高調波成分により、または、漏洩電流の高調波成分及び基本波成分の組み合わせにより、漏電電流基本波成分のアンバランスを補正し、前記アンバランスを補正した漏電電流基本波成分と、この漏電電流基本波成分の線間電圧基本波成分に対する位相角とを用いて地絡電流を演算する手段と、
    を備えたことを特徴とする地絡電流検出装置
    For a three-phase power distribution system having a three-phase delta-connected AC power source and one phase grounded, using the leakage current of the distribution system and the phase angle of the leakage current with respect to the line voltage, in ground fault current detector for calculating a ground fault current due to ground insulation resistance of the distribution system,
    Means for detecting a leakage current of the distribution system;
    Means for detecting a line voltage of the distribution system;
    Means for extracting a fundamental wave component and a harmonic component from the leakage current and the line voltage;
    Means for compensating a signal attenuated by an internal filter of the ground fault current detection device when extracting a fundamental wave component and a harmonic component from the leakage current and a line voltage according to the order of the harmonic component;
    Means for detecting a phase angle of the leakage current with respect to the line voltage;
    Correct the unbalance of the leakage current fundamental wave component by the harmonic component of the leakage current due to the unbalance of the electrostatic capacitance to the distribution system or by the combination of the harmonic component and fundamental wave component of the leakage current. Means for calculating a ground fault current using the leakage current fundamental wave component corrected for the unbalance and the phase angle of the leakage current fundamental wave component with respect to the line voltage fundamental wave component;
    Ground fault current detecting device characterized by comprising a.
JP2009205700A 2009-09-07 2009-09-07 Ground fault current detection method and detection apparatus Active JP5494929B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2009205700A JP5494929B2 (en) 2009-09-07 2009-09-07 Ground fault current detection method and detection apparatus

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2009205700A JP5494929B2 (en) 2009-09-07 2009-09-07 Ground fault current detection method and detection apparatus

Publications (2)

Publication Number Publication Date
JP2011058826A JP2011058826A (en) 2011-03-24
JP5494929B2 true JP5494929B2 (en) 2014-05-21

Family

ID=43946653

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2009205700A Active JP5494929B2 (en) 2009-09-07 2009-09-07 Ground fault current detection method and detection apparatus

Country Status (1)

Country Link
JP (1) JP5494929B2 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103995189B (en) * 2014-06-04 2017-01-04 国家电网公司 Three-phase condenser bank unbalance voltage loop check method
WO2016038651A1 (en) * 2014-09-08 2016-03-17 株式会社日立製作所 Insulation diagnosis system or rotating machine
JP6922816B2 (en) * 2018-03-29 2021-08-18 オムロン株式会社 Insulation measuring device and insulation measuring method
CN110133452B (en) * 2019-07-01 2020-03-10 华北电力大学 Mixed-voltage same-tower fault phase selection method based on waveform correlation coefficient and current mutation quantity

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0692995B2 (en) * 1992-04-24 1994-11-16 光商工株式会社 Insulation monitoring method in low piezoelectric path
JP4167872B2 (en) * 2001-10-04 2008-10-22 株式会社日立産機システム Leakage current monitoring device and monitoring system therefor
JP4143463B2 (en) * 2003-04-21 2008-09-03 三菱電機株式会社 Insulation monitoring device
JP4563144B2 (en) * 2004-11-11 2010-10-13 株式会社ネットインデックス Leakage current detection method and leak current detection device

Also Published As

Publication number Publication date
JP2011058826A (en) 2011-03-24

Similar Documents

Publication Publication Date Title
US8823307B2 (en) System for detecting internal winding faults of a synchronous generator, computer program product and method
US7999557B2 (en) Method for determining location of phase-to-earth fault
JP5672369B2 (en) Determination of fault current component of differential current
US8044666B2 (en) Method for determining location of phase-to earth fault
US10088546B2 (en) Method and apparatus to diagnose current sensor polarities and phase associations for a three-phase electric power system
JP4599120B2 (en) Electrical installation insulation monitoring device and method
US9829519B2 (en) Method and apparatus to commission voltage sensors and branch circuit current sensors for branch circuit monitoring systems
JP5494929B2 (en) Ground fault current detection method and detection apparatus
JP2013036884A (en) Insulation monitoring method and insulation monitor
JP4143463B2 (en) Insulation monitoring device
JP4993728B2 (en) Effective leakage current measuring instrument
US9897647B2 (en) Method and apparatus to commission voltage sensors and branch circuit current sensors for branch circuit monitoring systems
JP2007071774A (en) Insulation measuring method and apparatus therefor
JP4993727B2 (en) Leakage current measuring instrument
JP2011137718A (en) Device for monitoring high voltage insulation
JP5743296B1 (en) Leakage location exploration method and apparatus
JP2006010608A (en) Insulation level monitoring method for non-earthing electric line and device thereof
US20170331278A1 (en) Differential protection method and differential protection device for a transformer
KR101909379B1 (en) Leakage current measuring method and leakage current measuring apparatus
JP2009058235A (en) Leak current measuring instrument for electric path and electric apparatus, and its method
JP2008309681A (en) Insulation deterioration monitoring device and its method
JP2004242404A (en) Leakage detector
JP2011149959A (en) Insulation monitoring device
JP5501820B2 (en) Line characteristic calculation device and line characteristic calculation method
KR101276171B1 (en) insulation monitoring system

Legal Events

Date Code Title Description
A625 Written request for application examination (by other person)

Free format text: JAPANESE INTERMEDIATE CODE: A625

Effective date: 20120809

A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20131010

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20131017

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20131119

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20140205

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20140218

R150 Certificate of patent or registration of utility model

Ref document number: 5494929

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250