JP2005184906A - Method and apparatus of detecting ground fault of distribution system - Google Patents

Method and apparatus of detecting ground fault of distribution system Download PDF

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JP2005184906A
JP2005184906A JP2003419103A JP2003419103A JP2005184906A JP 2005184906 A JP2005184906 A JP 2005184906A JP 2003419103 A JP2003419103 A JP 2003419103A JP 2003419103 A JP2003419103 A JP 2003419103A JP 2005184906 A JP2005184906 A JP 2005184906A
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phase
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ground fault
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JP4114929B2 (en
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Tomoyoshi Shinkawa
智祥 新川
Naoteru Kawamura
直輝 川村
Yasunobu Fujita
康信 藤田
Shindai Sato
深大 佐藤
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Hitachi Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To reduce the size of an apparatus by detecting ground fault current at a ground fault accident time with high sensitivity by a three-phase current transformer for detecting the ground fault current and overcurrent flowing to a distribution line. <P>SOLUTION: The apparatus of detecting the ground fault of a distribution system includes first and second storing and holding means 305, 304 which always stores and holds a line voltage 303 and zero-phase current 302 generated at three-phase power line for several cycle part, a phase difference detecting means 307 for obtaining a phase difference of the line voltage from a present value by taking out the stored and held value of one cycle part of the line voltage from the first storing and holding means at the time of detecting zero-phase voltage 301 by a ground fault overvoltage relay, a phase correcting means 308 for phase correcting the zero phase current value stored and held in the second storing and holding means by using the phase difference, a zero-phase current difference arithmetic means 309 for obtaining the current change part by arbitrarily performing the calculation of the difference between the zero-phase current value and the present detected value which are phase corrected, and a ground fault direction relay calculating means 300 for detecting the current change part as the ground fault current. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、配電系統の地絡検出方法および装置に係り、特に、受変電設備の地絡電流を検出する技術に関する。   The present invention relates to a ground fault detection method and apparatus for a distribution system, and more particularly to a technique for detecting a ground fault current of a power receiving / transforming facility.

従来の非接地系統における地絡検出装置の回路を図３に示す。１００は三相非接地系統の母線、１０１は三相非接地系統の母線１００に接続した地絡検出対象となる配電線、１０２は三相非接地系統の母線１００と三相非接地系統の母線１００に接続した地絡検出対象となる配電線１０１を分離する遮断器、１０３は三相非接地系統の母線１０１に接続した地絡検出対象となる配電線１０２に流れる地絡電流ｉ１を検出する零相変流器、１０４は三相非接地系統の母線１００に接続した地絡検出対象となる配電線１０１に流れる電流を二次出力する三相分の変流器、１０５は地絡事故点、１０６は三相非接地系統の母線１００に接続させる接地形計器用変圧器であり、３次のオープンデルタ回路１０６(a)の構成となっている。１０７は制限抵抗、１０８は地絡過電圧継電器、１０９は過電流継電器、１１０は三相分の変流器１０４の二次回路、１１１は三相分の二次残留回路、１１２は地絡方向継電器である。
次に、動作について説明する。地絡事故点１０５で地絡が発生すると、三相非接地系統の母線１００には地絡電圧が発生する。この地絡電圧は、接地形計器用変圧器１０６の３次側オープンデルタ回路１０６（a）を介して検出される。一方、地絡電流は零相変流器１０３の二次出力により検出される
以上の接地形計器用変圧器１０６による地絡電圧と零相変流器１０３による地絡電流により地絡方向継電器１１２で地絡故障を判定し、遮断器１０２を開放して三相非接地系統の母線１００に接続した地絡検出対象となる配電線１０１を切り離す検出方式となっている。
一方、配電線１０１には短絡故障に備えた過電流継電器１０９が具備されており、これは上記の零相変流器１０３とは別に三相の変流器１０４の二次回路１１０に接続されている。また、接地形計器用変圧器１０６の３次側オープンデルタ回路１０６(a)には電路地絡時に発生する地絡電圧を検出する地絡過電圧継電器１０８が接続されている。
また、他の従来例として、上記の零相変流器（１０３）を省略するために、接地形計器用変圧器（１０６）の３次側オープンデルタ回路（１０６（ａ））に設けた制限抵抗（１０７）と並列に低インピーダンス回路を接続し、地絡事故時に地絡電流（ｉ１）をこの低インピーダンス回路を介して流し、地絡電流（ｉ１）を増加させ、増加した地絡電流（ｉ１）を上記の三相の変流器（１０４）の２次残留回路（１１１）により検出し、地絡故障を判定する地絡検出装置が知られている（例えば、特許文献１参照）。 The circuit of the ground fault detection apparatus in the conventional non-ground system is shown in FIG. 100 is a bus of a three-phase ungrounded system, 101 is a distribution line to be detected for ground faults connected to the bus 100 of a three-phase ungrounded system, and 102 is a bus 100 of the three-phase ungrounded system and a bus of the three-phase ungrounded system A circuit breaker for separating the distribution line 101 to be detected for ground fault connected to 100, 103 detects a ground fault current i1 flowing in the distribution line 102 to be detected for ground fault connected to the bus line 101 of the three-phase non-grounded system. A zero-phase current transformer, 104 is a three-phase current transformer for secondary output of the current flowing through the distribution line 101 connected to the bus 100 of the three-phase ungrounded system, and 105 is a ground fault point. 106 are grounded instrument transformers connected to the bus 100 of the three-phase non-grounded system, and have a configuration of a third-order open delta circuit 106 (a). 107 is a limiting resistor, 108 is a ground fault overvoltage relay, 109 is an overcurrent relay, 110 is a secondary circuit of the current transformer 104 for three phases, 111 is a secondary residual circuit for three phases, and 112 is a ground fault direction relay It is.
Next, the operation will be described. When a ground fault occurs at the ground fault point 105, a ground fault voltage is generated on the bus 100 of the three-phase ungrounded system. This ground fault voltage is detected through the tertiary open delta circuit 106 (a) of the grounded instrument transformer 106. On the other hand, the ground fault current is detected by the secondary output of the zero phase current transformer 103. The ground fault direction relay 112 is based on the above ground fault voltage by the grounded instrument transformer 106 and the ground fault current by the zero phase current transformer 103. In this detection method, the ground fault is determined, and the circuit breaker 102 is opened to disconnect the distribution line 101 that is the ground fault detection target connected to the bus 100 of the three-phase ungrounded system.
On the other hand, the distribution line 101 is provided with an overcurrent relay 109 for short-circuit failure, which is connected to the secondary circuit 110 of the three-phase current transformer 104 in addition to the zero-phase current transformer 103 described above. ing. Further, a ground fault overvoltage relay 108 for detecting a ground fault voltage generated at the time of an electric circuit ground fault is connected to the tertiary side open delta circuit 106 (a) of the earthing type instrument transformer 106.
Further, as another conventional example, in order to omit the above-described zero-phase current transformer (103), a restriction provided in the tertiary open delta circuit (106 (a)) of the grounded-type instrument transformer (106). A low impedance circuit is connected in parallel with the resistor (107), and a ground fault current (i1) is caused to flow through the low impedance circuit in the event of a ground fault, thereby increasing the ground fault current (i1) and increasing the ground fault current ( There is known a ground fault detection device for detecting a ground fault by detecting i1) by the secondary residual circuit (111) of the three-phase current transformer (104) (see, for example, Patent Document 1).

特開２０００−３５４６５５号公報JP 2000-354655 A

以上のように、従来の図３に示した非接地系統の地絡方向継電器１１２は、接地形計器用変圧器１０６の３次側オープンデルタ回路出力と三相非接地系統の母線１００に接続した地絡検出対象となる配電線１０１の零相変流器１０３の二次出力を用いて検出しており、三相非接地系統の母線１００に接続した地絡検出対象となる配電線１０１には、この外に過電流継電器１０９に対応した三相の変流器１０４が具備されている。このため、配電線１０１には三相の変流器１０４と零相変流器１０３の二種類を具備する必要があり、検出装置及び配電盤の大型化は避けられなかった。
また、定常状態での三相の変流器１０４の二次残留回路１１１には、短絡時の過電流に備えて変流比を大きくしてあるために、三相個別の変流器１０４の特性不揃いにより常時に零相電流が流れており、しかもその値は地絡電流発生時の接地形計器用変圧器１０６の３次側オープンデルタ回路１０６（a）に接続されている抵抗１０７で制限された地絡電流と比べて大きなものであり、検出が難しい点があった。
また、他の従来例として説明した地絡検出装置は、零相変流器（１０３）を省略するため、検出装置及び配電盤を小型化することができるが、地絡故障を判定する地絡検出に当たって、地絡事故時に地絡電流（ｉ１）を低インピーダンス回路を介して流し、この地絡電流（ｉ１）を増加させることによる検出であるため、地絡検出を高感度で検出することができない。 As described above, the ground fault direction relay 112 of the non-ground system shown in FIG. 3 is connected to the output of the tertiary open delta circuit of the grounded instrument transformer 106 and the bus 100 of the three-phase non-ground system. Detection is performed using the secondary output of the zero-phase current transformer 103 of the distribution line 101 that is the ground fault detection target, and the distribution line 101 that is the ground fault detection target connected to the bus 100 of the three-phase ungrounded system includes In addition, a three-phase current transformer 104 corresponding to the overcurrent relay 109 is provided. For this reason, it is necessary to provide the distribution line 101 with two types of the three-phase current transformer 104 and the zero-phase current transformer 103, and it is inevitable to increase the size of the detection device and the distribution board.
In addition, the secondary residual circuit 111 of the three-phase current transformer 104 in a steady state has a large current transformation ratio in preparation for an overcurrent at the time of a short circuit. A zero-phase current always flows due to the characteristic irregularity, and the value is limited by the resistor 107 connected to the tertiary open delta circuit 106 (a) of the grounded instrument transformer 106 when the ground fault current is generated. It was large compared to the ground fault current and was difficult to detect.
In addition, the ground fault detection device described as another conventional example omits the zero-phase current transformer (103), so that the detection device and the switchboard can be reduced in size. In this case, since the detection is performed by causing the ground fault current (i1) to flow through the low impedance circuit at the time of the ground fault and increasing the ground fault current (i1), the ground fault detection cannot be detected with high sensitivity. .

本発明の課題は、配電線に流れる地絡電流及び過電流を検出する三相分変流器により、地絡事故時の地絡電流を高感度で検出するに好適な配電系統の地絡検出方法および装置を提供することにある。   An object of the present invention is to detect a ground fault in a distribution system suitable for detecting a ground fault current at the time of a ground fault with high sensitivity by a three-phase current transformer that detects a ground fault current and an overcurrent flowing in a distribution line. It is to provide a method and apparatus.

上記課題を解決するために、常時三相配電線に生じる線間電圧および零相電流を数サイクル分記憶保持し、地絡過電圧継電器により三相母線の零相電圧を検出した時点に、三相配電線に生じる線間電圧１サイクル分の記憶保持値を取出し、当該線間電圧の現状値との位相差を求め、当該位相差を用いて記憶保持した三相配電線の零相電流値の位相補正を行い、当該位相補正を行った零相電流値と現在検出値との差分演算を随時行って電流変化分を求め、当該電流変化分を地絡電流として検出する。   In order to solve the above problems, the line voltage and zero phase current generated in the three phase distribution line are always stored for several cycles, and when the zero phase voltage of the three phase bus is detected by the ground fault overvoltage relay, the three phase distribution line The memory retention value for one cycle of the line voltage generated in the circuit is taken out, the phase difference from the current value of the line voltage is obtained, and the phase correction of the zero-phase current value of the three-phase distribution line stored using the phase difference is performed. Then, a difference between the zero-phase current value subjected to the phase correction and the current detection value is calculated as needed to obtain a current change, and the current change is detected as a ground fault current.

本発明によれば、常時配電線の線間電圧の波形値を取得し、地絡電圧発生時に、前記取得した線間電圧の波形値と現在の線間電圧波形値との位相差を検出し、この位相差を用いて常時取得した配電線の零相電流の波形値の位相補正を行い、この位相補正を行った零相電流の波形値と現在の零相電流の波形値との差分演算を行って電流変化分を求め、地絡電流として検出するので、連続して地絡電流の検出が可能となり、検出感度の高精度化を図ることができる。
また、三相分の変流器の二次残留回路による地絡電流を零相電流差分方式による地絡方向継電器で地絡故障を判定するので、零相変流器の設置を省略でき、地絡検出装置及び地絡検出装置を使用した配電盤を小型化することができる。 According to the present invention, the waveform value of the line voltage of the constant distribution line is acquired, and when the ground fault voltage is generated, the phase difference between the acquired waveform value of the line voltage and the current line voltage waveform value is detected. The phase of the waveform value of the zero-phase current of the distribution line that is always acquired using this phase difference is corrected, and the difference between the waveform value of the zero-phase current and the waveform value of the current zero-phase current is calculated. The current change is obtained and detected as a ground fault current, so that the ground fault current can be continuously detected and the detection sensitivity can be increased in accuracy.
In addition, since the ground fault is judged by the ground fault direction relay using the zero phase current difference method for the ground fault current due to the secondary residual circuit of the current transformer for three phases, installation of the zero phase current transformer can be omitted, The switchboard using the fault detection device and the ground fault detection device can be reduced in size.

以下、本発明を実施するための最良の形態を図面を用いて説明する。   The best mode for carrying out the present invention will be described below with reference to the drawings.

図１は、本発明の実施例１である配電系統の地絡検出方法を説明するための地絡検出回路図を示す。
図１において、２００は三相非接地系統の母線、２０１は三相非接地系統の母線２００に接続した地絡検出対象となる配電線、２０２は三相非接地系統の母線１と三相非接地系統の母線２００に接続した地絡検出対象となる配電線２０１を分離する遮断器、２０３は三相非接地系統の母線２００に接続した地絡検出対象となる配電線２０１に流れる電流を二次出力する三相分の変流器、２０４は地絡事故点、２０５は三相非接地系統の母線２００に接続させる接地形計器用変圧器であり、３次のオープンデルタ回路２０５(a)の構成となっている。２０６は制限抵抗、２０７は地絡過電圧継電器、２０８は過電流継電器、２０９は三相分の変流器２０３の二次回路、２１０は三相分の二次残留回路であり、２１１が変流器２０３の二次残留回路に流れる零相電流の位相差を調整した状態で変化分を入力とする地絡方向継電器である。地絡方向継電器２１１は、地絡電流ｉ１が接地Ｅ１とＥ２間にてどの方向に流れるか否か見ているので、一種の方向性継電器とみなすことができる。
地絡事故点２０４で地絡が発生すると、配電線２０１に生じた地絡事故点２０４の地絡電流ｉ１が接地Ｅ２から接地形計器用変圧器２０５の接地Ｅ１と三相母線２００及び三相配電線２０１を介して接地Ｅ２に循環して流れる。この電流は、三相分の変流器２０３の二次残留回路２１０にも変流比に応じた値の電流が流れる。一方、三相分の変流器２０３の二次残留回路２１０には、変流器２０３の三相個々の特性不揃いにより定常的に地絡電流を超えるような零相電流に地絡による地絡電流が加算されて検出を行っている。 FIG. 1 is a ground fault detection circuit diagram for explaining a ground fault detection method for a distribution system that is Embodiment 1 of the present invention.
In FIG. 1, 200 is a bus of a three-phase ungrounded system, 201 is a distribution line to be detected for grounding connected to a bus 200 of a three-phase ungrounded system, 202 is a bus 1 and three-phase non-connected of a three-phase ungrounded system. A circuit breaker 203 for separating the distribution line 201 to be grounded detection target connected to the bus 200 of the grounding system, and a current 203 flowing through the distribution line 201 to be grounded detection target connected to the bus 200 of the three-phase non-grounded system. The next-output three-phase current transformer, 204 is the ground fault point, 205 is a grounded instrument transformer connected to the bus 200 of the three-phase ungrounded system, and the third-order open delta circuit 205 (a) It becomes the composition of. 206 is a limiting resistor, 207 is a ground fault overvoltage relay, 208 is an overcurrent relay, 209 is a secondary circuit of a current transformer 203 for three phases, 210 is a secondary residual circuit for three phases, 211 is a current transformation This is a ground fault direction relay that inputs the amount of change while adjusting the phase difference of the zero-phase current flowing in the secondary residual circuit of the device 203. The ground fault directional relay 211 can be regarded as a kind of directional relay because it sees in which direction the ground fault current i1 flows between the grounds E1 and E2.
When a ground fault occurs at the ground fault point 204, the ground fault current i1 at the ground fault point 204 generated in the distribution line 201 changes from the ground E2 to the ground E1, the three-phase bus 200, and the three-phase distribution of the grounded instrument transformer 205. It circulates and flows through the electric wire 201 to the ground E2. This current also flows in the secondary residual circuit 210 of the current transformer 203 for three phases according to the current transformation ratio. On the other hand, the secondary residual circuit 210 of the three-phase current transformer 203 has a ground fault due to a ground fault due to a zero-phase current that constantly exceeds the ground fault current due to the irregular characteristics of the three phases of the current transformer 203. Detection is performed by adding current.

次に、地絡方向継電器２１１の回路構成と動作を図２を用いて説明する。
３００は地絡方向継電器２１１の演算回路、３０１は接地形計器用変圧器２０５の３次側オープンデルタ回路２０５（a）を介して検出される零相電圧、３０２は三相分の変流器２０３の二次残留回路２１０に流れる零相電流、３０３は配電線２０１の線間電圧である。
３０４は、三相分の変流器２０３の二次残留回路２１０を用いて零相電流を検出し、随時現在値を更新する零相電流波形記憶保持回路である。３０５は、配電線２０１の線間電圧を検出し、随時現在値を更新する線間電圧波形記憶保持回路である。３０６は、零相電圧波形監視回路であり、三相非接地系統の母線２００に接続させる接地形計器用変圧器２０５にて３次側オープンデルタ回路２０５（a）より零相電圧を検出し、随時現在値を更新する回路である。３０７は、線間電圧波形記憶保持領域３１３に記憶保持している波形値と、現在の波形値により位相差を検出する位相差検出回路である。３０８は、位相差検出回路３０７より計測された位相差分を用いて零相電流波形記憶保持領域３１４に記憶保持された１サイクル分の零相電流の位相を補正する位相補正回路である。３０９は、位相補正回路３０８により位相補正を行った零相電流波形記憶保持領域３１４に記憶保持された零相電流値と現在値の差分演算を行い、三相分の変流器２０３の二次残留回路２１０に流れる零相電流の変化分を検出する零相電流差分演算回路である。３１０は、３次側オープンデルタ回路２０５（a）より検出した零相電圧の現在値３１２と差分演算３０９により演算された零相電流のノイズ分を除去するための基本波抽出用フィルタ回路である。 Next, the circuit configuration and operation of the ground fault direction relay 211 will be described with reference to FIG.
300 is an arithmetic circuit of the ground fault direction relay 211, 301 is a zero-phase voltage detected via the tertiary open delta circuit 205 (a) of the grounded instrument transformer 205, and 302 is a current transformer for three phases. A zero-phase current flowing in the secondary residual circuit 210 of 203, 303 is a line voltage of the distribution line 201.
304 is a zero-phase current waveform memory holding circuit that detects the zero-phase current using the secondary residual circuit 210 of the current transformer 203 for three phases and updates the current value as needed. Reference numeral 305 denotes a line voltage waveform memory holding circuit that detects the line voltage of the distribution line 201 and updates the current value at any time. 306 is a zero-phase voltage waveform monitoring circuit, which detects the zero-phase voltage from the tertiary open delta circuit 205 (a) by the grounded instrument transformer 205 connected to the bus 200 of the three-phase ungrounded system, This circuit updates the current value at any time. Reference numeral 307 denotes a phase difference detection circuit that detects a phase difference based on the waveform value stored and held in the line voltage waveform storage and holding area 313 and the current waveform value. Reference numeral 308 denotes a phase correction circuit that corrects the phase of the zero-phase current for one cycle stored and held in the zero-phase current waveform storage and holding area 314 using the phase difference measured by the phase difference detection circuit 307. 309 calculates the difference between the zero-phase current value stored in the zero-phase current waveform storage / holding area 314 whose phase has been corrected by the phase correction circuit 308 and the current value, and the secondary of the current transformer 203 for three phases. This is a zero-phase current difference calculation circuit that detects a change in the zero-phase current flowing in the residual circuit 210. Reference numeral 310 denotes a fundamental wave extraction filter circuit for removing the noise component of the zero-phase current calculated by the difference calculation 309 and the current value 312 of the zero-phase voltage detected by the tertiary side open delta circuit 205 (a). .

次に、この回路の動作について説明する。
接地形計器用変圧器２０５で零相電圧（Ｖ０）３０１を計測し、零相電圧波形監視回路３０６で定常状態と判断している時、異常検出する異常スイッチ３１１がＯＦＦの状態となり、零相電流波形記憶保持回路３０４と線間電圧波形記憶保持回路３０５では異常スイッチの監視の結果が異常スイッチＯＮでないので、零相電流（Ｉ０）３０２および線間電圧（Ｖｒｓ）３０３の波形を常時数サイクル分を零相電流波形記憶保持領域３１４および線間電圧波形記憶保持領域３１３に記憶する。
しかし、零相電圧波形監視回路３０６にて異常時と判断した場合、異常スイッチ３１１がＯＮの状態となり、零相電流波形記憶保持領域３１４と線間電圧波形記憶保持領域３１３より１サイクル分の波形値を出力する。
線間電圧波形記憶保持回路３０５では、現在の線間電圧値（Ｖｒｓ）３０３および線間電圧波形記憶保持領域３１３に記憶保持された線間電圧（Ｖｒｓ）３１３を１サイクル分を抽出し、位相差検出回路３０７に入力し、位相差を検出する。
位相差検出回路３０７により検出した位相差を位相補正回路３０８に入力する。位相補正回路３０８では、零相電流波形記憶保持領域３１４に記憶保持された１サイクル分の零相電流（Ｉ０）を取出し、当該位相補正回路３０８に入力し、この記憶保持された零相電流（Ｉ０）３１４と現在の零相電流（Ｉ０）３０２との位相差の補償を行うため、位相差検出回路３０７により検出した位相差分を用いて記憶保持された零相電流（Ｉ０）３１４の位相を補正する。
その後、位相補正を行った零相電流波形記憶保持領域３１４に記憶保持された零相電流値（Ｉ０）３１４を差分演算回路３０９に入力すると共に、現在の零相電流（Ｉ０）３０２を入力し、差分演算を行う。 Next, the operation of this circuit will be described.
When the zero-phase voltage (V0) 301 is measured by the grounded-type instrument transformer 205 and the steady-state state is judged by the zero-phase voltage waveform monitoring circuit 306, the abnormality switch 311 for detecting the abnormality is turned off, and the zero-phase voltage is detected. In the current waveform memory holding circuit 304 and the line voltage waveform memory holding circuit 305, since the result of monitoring the abnormal switch is not ON, the waveforms of the zero-phase current (I0) 302 and the line voltage (Vrs) 303 are always several cycles. Minutes are stored in the zero-phase current waveform storage area 314 and the line voltage waveform storage area 313.
However, if the zero-phase voltage waveform monitoring circuit 306 determines that an abnormality has occurred, the abnormal switch 311 is turned on, and the waveform for one cycle is obtained from the zero-phase current waveform storage area 314 and the line voltage waveform storage area 313. Output the value.
The line voltage waveform memory holding circuit 305 extracts the current line voltage value (Vrs) 303 and the line voltage (Vrs) 313 stored and held in the line voltage waveform memory holding area 313 for one cycle. The signal is input to the phase difference detection circuit 307 and the phase difference is detected.
The phase difference detected by the phase difference detection circuit 307 is input to the phase correction circuit 308. In the phase correction circuit 308, the zero-phase current (I0) for one cycle stored and held in the zero-phase current waveform storage and holding area 314 is taken out and input to the phase correction circuit 308, and this stored and held zero-phase current ( I0) 314 and the current zero-phase current (I0) 302 are compensated for by using the phase difference detected by the phase difference detection circuit 307 to store the phase of the zero-phase current (I0) 314. to correct.
Thereafter, the zero-phase current value (I0) 314 stored and held in the zero-phase current waveform storage and holding area 314 subjected to phase correction is input to the difference calculation circuit 309 and the current zero-phase current (I0) 302 is input. The difference calculation is performed.

ここで、零相電流の差分演算法の原理について図４を用いて説明する。この差分演算法は、事故前後の電流について行うが、零相電圧（Ｖ０）が整定値より大きくなったとき、スイッチを開いて現在取り込んだ残留回路電流（現在データ）（１）と、予めメモリに記憶していた１サイクル前の電流（２）で差分計算した値（３）を真の零相電流として検出する。この様子を波形で表すと、同右図のようになる。   Here, the principle of the zero-phase current difference calculation method will be described with reference to FIG. This difference calculation method is performed on the current before and after the accident. When the zero-phase voltage (V0) becomes larger than the set value, the residual circuit current (current data) (1) that is currently acquired by opening the switch is stored in the memory in advance. The value (3) obtained by calculating the difference with the current (2) one cycle before that is stored in is detected as a true zero-phase current. This situation can be represented by a waveform as shown on the right.

現在の零相電圧値（Ｖ０）３１２と、差分演算回路３０９より演算し終えた零相電流値（ΔＩ）を基本波抽出フィルタに入力し、地絡方向継電器演算回路３００にて出力診断を行う。演算結果が［Ｖ０・（ΔＩ）・ｃｏｓΦ＞＝Ｖ０・Ｉ０］のとき、地絡方向継電器が動作する。   The current zero-phase voltage value (V0) 312 and the zero-phase current value (ΔI) that has been calculated by the difference calculation circuit 309 are input to the fundamental wave extraction filter, and output diagnosis is performed by the ground fault relay calculation circuit 300. . When the calculation result is [V0 · (ΔI) · cosΦ> = V0 · I0], the ground fault direction relay operates.

以上説明したように、本実施例１では、零相電圧波形監視回路３０６と零相電流波形記憶保持回路３０４と線間電圧波形記憶保持回路３０５および位相差検出回路３０７と位相補正回路３０８を備え付けたことにより、記憶保持された地絡事故前の零相電流の値と現状値とを零相電流差分演算回路３０９で演算することになるので、連続して地絡電流の検出が可能となり、高精度の検出感度を持たせることができる。
この結果、図１の三相分の変流器２０３の二次残留回路２１０による地絡電流を零相電流差分方式による地絡方向継電器２１１で地絡故障を判定し、遮断器２０３を開放して地絡対象の配電線２０２を切り離すことができる。
このように、変流器２０３により地絡電流ｉ１の検出感度を向上させ、検出させることにより、零相変流器が省略できるようになり、零相変流器を用いない地絡検出装置を提供できる。 As described above, the first embodiment includes the zero-phase voltage waveform monitoring circuit 306, the zero-phase current waveform memory holding circuit 304, the line voltage waveform memory holding circuit 305, the phase difference detection circuit 307, and the phase correction circuit 308. As a result, the stored zero-phase current value before the ground fault accident and the current value are calculated by the zero-phase current difference calculation circuit 309, so that the ground fault current can be continuously detected. Highly accurate detection sensitivity can be provided.
As a result, the ground fault current from the secondary residual circuit 210 of the current transformer 203 of the three-phase current transformer 203 in FIG. 1 is determined by the ground fault direction relay 211 by the zero phase current difference method, and the circuit breaker 203 is opened. Thus, the distribution line 202 to be grounded can be disconnected.
Thus, by detecting and detecting the ground fault current i1 with the current transformer 203, the zero phase current transformer can be omitted, and a ground fault detection device that does not use the zero phase current transformer is provided. Can be provided.

本発明は、地絡電流の検出感度を向上させることができ、また、零相変流器の設置を省略したので、地絡検出装置及び地絡検出装置を使用した配電盤を小型化することができる。   The present invention can improve the detection sensitivity of the ground fault current and omits the installation of the zero-phase current transformer, so that the ground fault detection device and the switchboard using the ground fault detection device can be miniaturized. it can.

本発明の配電系統の地絡検出方法および装置を説明するための実施例１である地絡検出回路図FIG. 1 is a ground fault detection circuit diagram that is Embodiment 1 for explaining a ground fault detection method and apparatus for a distribution system according to the present invention; 本発明の地絡方向継電器の回路構成と動作の説明図Explanatory drawing of circuit configuration and operation of ground fault direction relay of the present invention 従来の地絡検出回路の回路図Circuit diagram of conventional ground fault detection circuit 零相電流の差分演算法の原理についての説明図Explanatory diagram of the principle of difference calculation method of zero phase current

符号の説明Explanation of symbols

２００…三相非接地系統の母線、２０１…配電線、２０２…遮断器、２０３…三相分の変流器、２０４…地絡事故点、２０５…接地形計器用変圧器、２０５(a)…接地形計器用変圧器側の３次側オープンデルタ回路、２０６…制限抵抗、２０７…地絡過電圧継電器、２０８…過電流継電器、２０９…三相分の変流器２０３の二次回路、２１０…三相分の変流器２０３の二次残留回路、２１１…地絡方向継電器、２１２…線間電圧
３００…地絡方向継電器の演算回路、３０１…零相電圧、３０２…零相電流、３０３…線間電圧、３０４…零相電流波形記憶保持回路、３０５…線間電圧波形記憶保持回路、３０６…零相電圧波形監視回路、３０７…位相差検出回路、３０８…位相補正回路、３０９…零相電流差分演算回路、３１０…基本波抽出用フィルタ回路、３１１…異常スイッチ、３１２…現在の零相電圧、３１３…線間電圧波形記憶保持領域、３１４…零相電流波形記憶保持領域

DESCRIPTION OF SYMBOLS 200 ... Bus line of three-phase non-ground system, 201 ... Distribution line, 202 ... Circuit breaker, 203 ... Current transformer for three phases, 204 ... Ground fault point, 205 ... Grounded instrument transformer, 205 (a) 3rd side open delta circuit on the grounded transformer side, 206 ... Limiting resistor, 207 ... Ground fault overvoltage relay, 208 ... Overcurrent relay, 209 ... Secondary circuit of current transformer 203 for three phases, 210 ... secondary residual circuit of current transformer 203 for three phases, 211 ... ground fault direction relay, 212 ... line voltage 300 ... arithmetic circuit of ground fault direction relay, 301 ... zero phase voltage, 302 ... zero phase current, 303 ... Line voltage 304 ... Zero phase current waveform memory holding circuit 305 ... Line voltage waveform memory holding circuit 306 ... Zero phase voltage waveform monitoring circuit 307 ... Phase difference detection circuit 308 ... Phase correction circuit 309 ... Zero Phase current difference calculation circuit, 310... Filter circuit, 311 ... Abnormal switch, 312 ... Current zero-phase voltage, 313 ... Line voltage waveform storage holding area, 314 ... Zero-phase current waveform storage holding area

Claims (2)

三相母線に３次側オープンデルタ回路を有する接地形計器用変圧器を接続し、三相配電線に遮断器と三相分の変流器を接続し、前記３次側オープンデルタ回路を介して検出される零相電圧と、前記三相分の変流器の二次残留回路に流れる零相電流と、前記三相配電線の線間電圧とを地絡方向継電器に入力し、前記地絡方向継電器により前記遮断器を開放する配電系統の地絡検出方法であって、
常時前記三相配電線に生じる線間電圧および零相電流を数サイクル分記憶保持し、前記地絡過電圧継電器により前記零相電圧を検出した時点に、前記線間電圧１サイクル分の記憶保持値を取出し、前記線間電圧の現状値との位相差を求め、当該位相差を用いて前記記憶保持した零相電流値の位相補正を行い、前記位相補正を行った零相電流値と現在検出値との差分演算を随時行って電流変化分を求め、当該電流変化分を地絡電流として検出することを特徴とする配電系統の地絡検出方法。 Connect a grounding-type instrument transformer with a tertiary open delta circuit to the three-phase bus, connect a circuit breaker and a three-phase current transformer to the three-phase distribution line, The detected zero-phase voltage, the zero-phase current flowing in the secondary residual circuit of the current transformer for three phases, and the line voltage of the three-phase distribution line are input to the ground fault direction relay, and the ground fault direction A ground fault detection method for a distribution system in which the circuit breaker is opened by a relay,
The line voltage and zero phase current generated in the three-phase distribution line are always stored for several cycles, and when the zero phase voltage is detected by the ground fault overvoltage relay, the stored value for one cycle of the line voltage is stored. Taking out, obtaining a phase difference from the current value of the line voltage, performing phase correction of the stored zero phase current value using the phase difference, and performing the phase correction of the zero phase current value and the current detection value A ground fault detection method for a power distribution system, characterized in that a current change is obtained by performing a difference calculation with the time and the current change is detected as a ground fault current. 三相母線に接続した３次側オープンデルタ回路を有する接地形計器用変圧器と、三相配電線に接続した遮断器および三相分の変流器と、前記３次側オープンデルタ回路を介して検出される零相電圧、前記三相分の変流器の二次残留回路に流れる零相電流および前記三相配電線の線間電圧とを地絡方向継電器に入力し、前記地絡方向継電器により前記遮断器を開放する配電系統の地絡検出装置であって、
常時前記三相配電線に生じる線間電圧および零相電流を数サイクル分記憶保持する第１および第２の記憶保持手段と、前記地絡過電圧継電器により前記零相電圧を検出した時点に、前記第１の記憶保持手段から前記線間電圧１サイクル分の記憶保持値を取出し、前記線間電圧の現状値との位相差を求める位相差検出手段と、当該位相差を用いて前記第２の記憶保持手段に記憶保持した零相電流値の位相補正を行う位相補正手段と、前記位相補正を行った零相電流値と現在検出値との差分演算を随時行って電流変化分を求める零相電流差分演算手段と、当該電流変化分を地絡電流として検出する地絡方向継電器演算手段とを備えることを特徴とする配電系統の地絡検出装置。

A grounding-type instrument transformer having a tertiary open delta circuit connected to a three-phase bus, a circuit breaker connected to a three-phase distribution line, a current transformer for three phases, and the tertiary open delta circuit The detected zero-phase voltage, the zero-phase current flowing in the secondary residual circuit of the current transformer for the three phases, and the line voltage of the three-phase distribution line are input to the ground fault direction relay, and the ground fault direction relay A ground fault detection device for a distribution system that opens the circuit breaker,
When the zero-phase voltage is detected by the first and second storage / holding means for always storing and holding the line voltage and the zero-phase current generated in the three-phase distribution line for several cycles, the first-phase voltage is detected by the ground fault overvoltage relay. A memory holding value for one cycle of the line voltage is extracted from one memory holding means, a phase difference detecting means for obtaining a phase difference from the current value of the line voltage, and the second memory using the phase difference. Phase correction means for correcting the phase of the zero-phase current value stored and held in the holding means, and zero-phase current for obtaining a current change by performing a difference calculation between the zero-phase current value subjected to the phase correction and the current detection value as needed. A ground fault detection device for a distribution system, comprising: a difference calculation means; and a ground fault direction relay calculation means for detecting the current change as a ground fault current.

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CN113567811B (en) * 2021-08-13 2023-02-17 广东电网有限责任公司 Distribution line single-phase fault detection method and related device

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