JPH0437650B2

JPH0437650B2 -

Info

Publication number: JPH0437650B2
Application number: JP2365984A
Authority: JP
Inventors: Shizuo Nomura; Shigenori Kurimoto; Takeyuki Ando; Kazumasa Ando; Mitsuyasu Furuse; Takaaki Kai
Original assignee: Meidensha Corp
Current assignee: Meidensha Corp
Priority date: 1984-02-10
Filing date: 1984-02-10
Publication date: 1992-06-22
Also published as: JPS619121A

Description

【発明の詳細な説明】[Detailed description of the invention]

（発明の技術分野）本発明は、高抵抗接地系平行４回線の地絡保護
方式に係り、特に３端子系統に対して優れた方式
を提供するものである。平行４回線系統において、系統構成によつては
系統の各相間の相互インダクタンスが不平衡とな
り負荷電流によつて誘導される回線間を循環する
誘導電流（以下循環電流と称する）が発生する。
特に、１回線停止、１回線停止かつ１端子開放時
で発生する循環電流は著しく、これは１線地絡時
に中性点抵抗器から供給される故障電流に較べて
無視できない。このため、循環電流の零相分（以
下零相循環電流と称する）で地絡保護リレーが誤
動作しないようリレータツプ値を上げている。従
つて、零相循環電流の増加に伴ない高感度の保護
ができないという問題がある。平行４回線系統を地絡故障から保護する回線選
択継電方式に於いては、これまで前述の問題解決
のため、常時の零相電流を記憶しておき、故障時
の零相電流の変化分によつて故障回線の判別を行
う方法がある。ところが、この方式は原理上、故
障前後の零相電流の変化分で応動するために、相
手端近傍の内部故障で相手端が先行してしや断
（シリーストリツプ）した場合は、零相循環電流
が変化するので故障回線の判別が難かしい。この
ために、２端子系統では故障発生後一定時間（相
手端先行しや断以前の時間）経過すると従来の回
線選択継電器に切り換えて故障回線の判別を行う
方式がとられているが３端子系統では、相手端先
行しや断を２回経験する３段階シリーストリツプ
で故障が除去されるために上記の方式では充分な
効果が期待できない。さらに別の方式として１線地絡時に測定可能な
健全相循環電流に対してベクトル定数（以下補償
定数と称す）を掛けて零相循環電流を演算し、次
に地絡回線選択継電器の入力電流である回線間零
相差電流（以下零相差電流と称す）は故障電流と
零相循環電流が合成されたものであるため、零相
差電流から上記零相循環電流の演算値を差し引き
故障電流成分のみを検出し、この検出値を地絡回
線選択継電器の新たな入力電流として故障回線選
択をする方式がある。この方式は後に詳細に述べ
るが、負荷電流に逆相成分があるとこれが継電器
の誤差電流となつて検出感度を低下させる問題が
ありこれを解決する方法はこれまでなかつた。（発明の目的）本発明の目的は、負荷電流に逆相成分が存在す
る高抵抗接地系平行４回線３端子系統でも確実に
地絡回線を検出できる地絡回線選択継電器を提供
するにある。（発明の概要）本発明は高抵抗接地系平行多回線系統の回線間
差電流の２つの健全相の差電流から正相分を除外
した量について補償した地を回線間零相差電流か
ら引いた値を求める第１の手段と、回線間差電流
に生じる負荷正相電流の変化分を求める第２の手
段、と回線間和電流に生じる負荷和電流の変化方
向を求める第３の手段を有し、接絡故障発生から
最初のトリツプ（第１トリツプ）迄は、前記第１
の手段によつて得られた値に対して地絡故障発生
前後の変化分と極性量とによつて地絡回線を選択
し、第１トリツプ以降は第１の手段によつて得ら
れた値と前記第３の手段によつて求められた変化
方向に応じて、前記第２の手段によつて求められ
た値との和または差をとつた値と極性量とによつ
て地絡回線を選択することを特徴とするものであ
る。（実施例の構成）以下に本発明の実施例に係る地絡回線選択器に
ついて説明する。第１図は本発明を平行４回線３端子系統に適用
した場合を示すものである。１１〜１６は母線を
示し、３１〜３４は送電回線を示し、S₁〜S₆は電
気所を示す。送電回線３１〜３４はS₁からS₂まで
同一鉄塔に併架されている。送電回線３１，３２
は位置P₁、P₂より分岐してS₃まで平行２回線と
して構成される。送電回線３３，３４は位置P₃、
P₄より分岐してS₄まで平行２回線として構成さ
れる。さらに送電回線３３，３４は位置P₅、P₆
より分岐してS₅、S₆まで単独回線で構成される。 G₁〜G₇は送電回線の区間を示し、その鉄塔装
柱図が第２図Ａ〜Ｃに示される。この第２図で
ａ，ｂ，ｃは相を示す。上記の系統で負荷電流によつて誘導される循環
電流を大形計算機により系統シミユレーシヨンし
て零相循環電流を求めた結果を第１表に示す。系統シミユレーシヨン結果が示すように循環電
流はそれを誘導する負荷電流に比例する。これは
理論的にも確認されるが循環電流の性質を要約す
ると次の通りとなる。 (Technical Field of the Invention) The present invention relates to a ground fault protection system for a high resistance grounding system with four parallel circuits, and particularly provides an excellent system for a three-terminal system. In a parallel four-line system, depending on the system configuration, the mutual inductance between each phase of the system becomes unbalanced, and an induced current (hereinafter referred to as a circulating current) that circulates between the lines induced by the load current is generated.
In particular, the circulating current generated when one line is stopped, one line is stopped, and one terminal is open is significant and cannot be ignored compared to the fault current supplied from the neutral point resistor when one line is grounded. For this reason, the relay tap value is increased so that the ground fault protection relay does not malfunction due to the zero-sequence portion of the circulating current (hereinafter referred to as zero-sequence circulating current). Therefore, there is a problem in that highly sensitive protection cannot be achieved as the zero-phase circulating current increases. In the line selective relay system that protects parallel four-line systems from ground faults, in order to solve the above-mentioned problem, the constant zero-sequence current is memorized and the change in zero-sequence current at the time of a fault is calculated. There is a method of determining a faulty line by However, in principle, this method responds to the change in the zero-sequence current before and after a failure, so if the other end is suddenly disconnected (series strip) due to an internal fault near the other end, the zero-sequence circulating current changes, making it difficult to identify the faulty line. For this reason, in 2-terminal systems, a method is adopted in which the faulty line is determined by switching to a conventional line selection relay after a certain period of time has elapsed after the failure occurs (the time before the other end is preceded or disconnected), but in 3-terminal systems. In this case, the above method cannot be expected to be sufficiently effective because the failure is eliminated by a three-stage series strip in which the other end experiences leading and breaking twice. Another method is to calculate the zero-sequence circulating current by multiplying the measurable healthy phase circulating current by a vector constant (hereinafter referred to as a compensation constant) during a one-line ground fault, and then calculate the input current of the ground fault line selection relay. Since the inter-line zero-sequence difference current (hereinafter referred to as zero-sequence difference current) is a combination of the fault current and zero-sequence circulating current, subtracting the calculated value of the above zero-sequence circulating current from the zero-sequence difference current yields only the fault current component. There is a method in which the detected value is used as the new input current of the ground fault line selection relay to select the fault line. This method will be described in detail later, but if there is a negative phase component in the load current, this becomes an error current in the relay and reduces the detection sensitivity, and there has been no method to solve this problem. (Object of the Invention) An object of the present invention is to provide a ground fault line selection relay that can reliably detect a ground fault line even in a high-resistance grounded parallel four-line three-terminal system in which a negative phase component exists in the load current. (Summary of the Invention) The present invention subtracts the compensated ground from the zero-sequence difference current between lines in a high-resistance grounded parallel multi-line system by excluding the positive phase from the difference current between two healthy phases. The present invention has a first means for determining the value, a second means for determining a change in the load positive sequence current occurring in the inter-line difference current, and a third means for determining the direction of change in the load sum current occurring in the inter-line sum current. However, from the occurrence of a short circuit fault to the first trip (first trip), the first
A ground fault line is selected based on the amount of change before and after the occurrence of a ground fault fault and the amount of polarity with respect to the value obtained by the above method, and after the first trip, the value obtained by the first method is selected. and the value obtained by the second means, depending on the direction of change obtained by the third means, and the polarity amount. It is characterized by selection. (Configuration of Embodiment) A ground fault line selector according to an embodiment of the present invention will be described below. FIG. 1 shows the case where the present invention is applied to a parallel four-line three-terminal system. 11 to 16 indicate busbars, 31 to 34 indicate power transmission lines, and S ₁ to S ₆ indicate electric stations. The power transmission lines 31 to 34 are installed on the same tower from _S1 to _S2 . Power transmission lines 31, 32
is configured as two parallel lines branching from positions P ₁ and P ₂ to S ₃ . The power transmission lines 33 and 34 are at positions P ₃ ,
It is configured as two parallel lines branching from P ₄ to S ₄ . Furthermore, the power transmission lines 33 and 34 are located at positions P ₅ and P ₆
It branches out to S ₅ and S ₆ , each consisting of a single line. G ₁ to G ₇ indicate the sections of the power transmission line, and the tower installation diagrams thereof are shown in FIGS. 2A to C. In FIG. 2, a, b, and c indicate phases. Table 1 shows the results of a system simulation of the circulating current induced by the load current in the above system using a large-scale computer to determine the zero-sequence circulating current. As the system simulation results show, the circulating current is proportional to the load current inducing it. Although this is confirmed theoretically, the properties of circulating current can be summarized as follows.

【表】性質１ａ，ｂ，ｃ相及び零相循環電流Ｉ・ac、
Ｉ・bc、Ｉ・cc、Ｉ・ocは、それを誘導する負荷電
流に比例する。性質２その比例定数は、平行４回線系統運用状
態、その電線配置及び負荷電流分布によつて定
まる。性質３性質１、２より、次に定義する零相循環
電流Iocと２つの相循環電流から正相分を除外
した量とのベクトル比（補償定数といもいう）
は平行４回線系統運用状態（その電線配置）及
び負荷電流分布によつて定まる。但し、ａ＝exp（ｊ２／３）第１図の系統構成図を系統シミユレーシヨンし
て得られた各回線の循環電流により定数Ｋ・ａ、Ｋ・
ｂ、Ｋ・ｃを求めた結果を第２表に示す。[Table] Property 1 a, b, c phase and zero phase circulating current I・ac,
I·bc, I·cc, and I·oc are proportional to the load current that induces them. Property 2 The proportionality constant is determined by the operating status of the parallel 4-circuit system, its wire arrangement, and load current distribution. Property 3 From Properties 1 and 2, the vector ratio of the zero-sequence circulating current Ioc defined next to the amount obtained by excluding the positive-sequence component from the two phase circulating currents (also called a compensation constant)
is determined by the operating status of the parallel four-circuit system (its wire arrangement) and the load current distribution. However, a=exp(j2/3) The constants K・a, K・
The results of determining b and K·c are shown in Table 2.

【表】これと同じく、各回線の差電流（リレーに必要
な電流）例えば回線３１と３２との差電流に生じ
る循環電流から、(1)式に定義するベクトル比Ｋ・
ａ、Ｋ・ｂ、Ｋ・ｃについてもこの値は平行４回線の
系統運用状態（その電線配置）及びその負荷電流
分布によつて定まる。先に簡単に述べたが、従来方式で平行４回線系
統を地絡故障から保護する回線選択継電方式の一
つの方式とし、上記性質(1)〜(3)に基づいてなされ
たものがある。これについて詳しく述べる。回線３１と３２と
の地絡回線を選択する地絡回線選択リレーを例に
とる。ａ相の１線地絡故障が起きた場合に、回線
３１と３２との健全相であるｂ相、ｃ相差電流Ｉ・
bd、Ｉ・cdには故障電流成分は含まれず次のよう
になる（これ以後の差電流は回線３１と３２の差
電流を示す）。Ｉ・bd＝Ｉ・bc＋Ｉ・b_L Ｉ・cd＝Ｉ・cc＋Ｉ・c_L ……(2) 但し、Ｉｂ・_L、Ｉ・c_L：回線３１と３２との差電流に生じ
るｂ相及びｃ相負荷電流（以下負荷電流と称
す）。Ｉ・bc、Ｉ・cc：回線３１と３２との差電流に生じ
る誘導によるｂ相及びｃ相循環電流（以下循環
電流と称す）。差電流に負荷電流が含まれるのは分岐端負荷が
存在する場合や系統故障等によつて相手端先行し
や断された場合である。また、健全相差電流には故障電流成分は含まれ
ない。(2)式の負荷電流成分Ｉ・b_L、Ｉ・c_L、正相、逆
相成分Ｉ・_1L、Ｉ・_2Lで表現すると（零相成分は無い
とする）、Ｉ・bd＝Ｉ・bc＋a²Ｉ・_1L＋ａＩ・_2L Ｉ・cd＝Ｉ・cc＋ａＩ・_1L＋a²Ｉ・_2L ……(3) 但し、a²＝ε^-2/3〓、ａ＝ε_j2/3〓となる。このｂ相及びｃ相差電流から正相成分Ｉ・_1Lの影
響を取り除くために次の演算を行なう。Ｉ・bd−ａＩ・cd ＝（Ｉ・bc＋a²Ｉ・_1L＋ａＩ・_2L） −ａ（Ｉ・cc＋ａＩ・_1L＋a²Ｉ・_2L）＝（Ｉ・bc−ａＩ・cc）＋（ａ−１）Ｉ・_2L……(4
) ここで、ａ相地絡時の零相循環電流を演算する
ために(1)式に示すＫ・ａの値と(4)式の（Ｉ・bc−ａ
Ｉ・cd）とを掛けた演算値をＡとするとＡ＝Ｋ・ａ（Ｉ・bd−ａＩ・cd）＝Ｋ・ａ｛（Ｉ・bc−ａＩ・cc）＋（ａ−１）Ｉ・_2L｝＝I〓^es _pc＋（ａ−１）Ｋ・a
I_2L
……(5) 但しI〓^es _pc＝Ｋ・ａ（Ｉ・bc−ａＩ・cc）となる。このＡを零相循環電流の演算値と称す。
またI〓^es _pcを演算Ｉ・ocと称す。ｂ相、ｃ相地絡時も
同様の演算で求められ、次の第３表に示すように
なる。[Table] Similarly, from the circulating current generated in the differential current of each line (current required for the relay), for example, the differential current between lines 31 and 32, the vector ratio K.
The values of a, K.b, and K.c are also determined by the system operation status of the four parallel circuits (wire arrangement) and the load current distribution. As briefly mentioned earlier, there is a method of line selective relaying that protects a parallel four-line system from ground faults in the conventional method, based on properties (1) to (3) above. . I will discuss this in detail. A ground fault line selection relay that selects a ground fault line between lines 31 and 32 will be taken as an example. When a one-wire ground fault occurs in the a phase, the difference current between the healthy phases b and c between lines 31 and 32 is
bd and I.cd do not include fault current components and are as follows (the difference currents thereafter indicate the difference currents between lines 31 and 32). I・bd=I・bc+I・b _L I・cd=I・cc+I・c _L ...(2) However, Ib・_L , I・c _L : B phase and c generated in the difference current between lines 31 and 32 Phase load current (hereinafter referred to as load current). I·bc, I·cc: B-phase and C-phase circulating currents (hereinafter referred to as circulating currents) due to induction caused by the difference current between lines 31 and 32. The load current is included in the difference current when there is a load at the branch end or when the other end takes the lead or is cut off due to a system failure or the like. Further, the healthy phase difference current does not include a fault current component. Expressing the load current components I・b _L , I・c _L , positive phase and negative phase components I・_1L and I・_2L in equation (2) (assuming there is no zero-sequence component), I・bd=I・bc+a ² I・_1L +aI・_2L I・cd=I・cc+aI・_1L +a ² I・_2L ……(3) However, a ² =ε ^-2/3 〓, a=ε _j2/3 〓. In order to remove the influence of the positive phase component _I.1L from this b-phase and c-phase difference current, the following calculation is performed. I・bd−aI・cd =(I・bc+a ² I・_1L +aI・_2L ) −a(I・cc+aI・_1L +a ² I・_2L ) =(I・bc−aI・cc)+(a−1) I・_2L ...(4
) Here, in order to calculate the zero-sequence circulating current at the time of a-phase ground fault, the value of K・a shown in equation (1) and (I・bc−a
Let A be the calculated value multiplied by I・cd) A=K・a(I・bd−aI・cd) =K・a{(I・bc−aI・cc) +(a−1)I・_2L }=I〓 ^es _pc +(a-1)K・a
I _2L
...(5) However, I〓 ^es _pc = K・a(I・bc−aI・cc). This A is called the calculated value of the zero-phase circulating current.
Also, I〓 ^es _pc is called the operation I·oc. Similar calculations are performed for the ground faults of the b-phase and c-phase, and the results are shown in Table 3 below.

【表】次に、１線地絡時の零相差電流Ｉ・odは故障電
流Ｉ・_Fと零相循環電流Ｉ・ocとの和となり、Ｉ・od＝Ｉ・_F＋Ｉ・oc ……(6) このうち零相差電流Ｉ・odに含まれる零相循環
電流Ｉ・ocを補償するために上述の零相循環電流
の演算値Ａを用いて次の演算を行ない、継電器入
力Ｉ・inを求める。Ｉ・in＝Ｉ・od−Ａ＝Ｉ・_F＋Ｉ・oc−｛I〓
^es _pc＋（ａ−１）Ｋ・ａＩ・_2L｝＝Ｉ・_F−（ａ−１）Ｋ・ａＩ・_2L＋ΔＩ
・co……(7) 但しΔＩ・oc＝Ｉ・oc−I〓^es _pc ΔＩ・oc：誤差Ｉ・oc このような、従来方式において、負荷電流に逆
相成分Ｉ・_2L及び誤差Ｉ・ocがリレー誤差電流となり
故障電流Ｉ・_F成分が損なわれる。但し、誤差Ｉ・oc
であるΔIocについては後述するような例で定数
Ｋ・ａ、Ｋ・ｂ、Ｋ・ｃの値の設定方法で実用上さしつ
かえないほど充分に小さくすることができる。し
かし、負荷電流の逆相成分Ｉ・_2Lによるリレー誤差
電流による地絡回線選択リレーの感度低下の問題
点がある。本発明は負荷電流により誘導される循環電流及
び負荷電流の逆相成分に影響されることのない、
高抵抗接地系平行４回線３端子系統用回線選択継
電器を提供することを目的とし、３端子系を例に
とりその原理を以下に説明する。（第１実施例）地絡回線選択継電器は、自端の回線間零相差電
流（以下零相差電流と称す）の大きさと方向によ
つて故障回線を判別するものである。このため、
相手端近傍故障では相手端が先行しや断するまで
自端の零相差電流がないため、相手端が先行しや
断して自端がしや断するいわゆるシリース・トリ
ツプとなる。第３図Ａ，Ｂ，Ｃは平行４回線３端
子系統でのシリース・トリツプの一例を示す図で
ある。自端を電気所S₁とする。同図中、１は電
源、２は中性点接地抵抗であるNGR、４１１〜
４４４はしや断器、６２〜６６は相手端母線１２
〜１６に接続された負荷を示す。同図Ａは相手端
電気所S₂の近傍の回線３１のＦ点で地絡故障が発
生した場合を示す。この場合回線３１と３２の地
絡回線選択リレーが動作し電気所S₁、S₂、S₃の回
線３１に設置されたしや断器がトリツプするが自
端と他方の相手端電気所S₁、S₃の零相差電流は零
に近いため回線選択継電器は応動できない。この
ため第３図Ｂに示すように、相手端のしや断器４
１２によつて最先行しや断（又は第１トリツプ）
する。しや断器４１２が開になると、自端及び相
手端の零相差電流は増加するが、相手端の零相差
電流が地絡継電器の整定値を越え自端の零相差電
流が地絡継電器の整定値を越えない場合は第３図
Ｃに示すように他方の相手端のしや断器４１３が
しや断する（第２トリツプ）。その後、図示しな
いが自端の故障電流が増加し自端電気所S₁の地絡
回線選択継電器が動作し、しや断器４１１がトリ
ツプし故障除去される（第３トリツプ）。こうしたシリース・トリツプを考慮して、負荷
電流の逆相成分の影響を除外するのに、まず相手
端が先行しや断するまでは次の方法によつて継電
器入力電流を得る。第３図に示した電気所S₅及びS₆の負荷である１
回線受電のＴ分岐負荷によつて系統健全時に差電
流に現われる負荷電流の逆相成分をＩ・_2Lとする
と、零相循環電流が完全に補償された継電器入力
電流Ｉ・in（以下Ｉ・inは零相循環電流が完全に補償
された継電器入力電流とし、ΔＩ・_0c＝０とする。）
は前述の(7)式から _io＝（ａ−１）Ｋ・ａ・_2L ……(8) となる。（但し、_io、_2Lは系統健全時の量を意
味し、それぞれａ相地絡前の継電器入力電流と負
荷電流の逆相成分である。）次に、ａ相地絡発生から相手端先行しや断する
前の入力電流Ｉ・inは(7)式よりＩ・in＝Ｉ・_F＋（ａ−１）Ｋ・_a・Ｉ・_2L ……(9) となる。１線地絡時に負荷電流の逆相成分を自端
の電流のみから測定することは不可能であるが、
高抵抗接地系統では１線地絡時の線間電圧は系統
健全時と殆んど変らないので、Ｔ分岐負荷の大き
さが地絡故障発生前後で変化がないと仮定すれ
ば、それによつて差電流に現われる逆相成分も地
絡前後でほぼ一定値に保たれる（I_2L＝_2L）。従つて、地絡故障発生前後の継電器入力電流Ｉ・
inの変化分をΔＩ・inとすると、(8)、(9)式から △Ｉ・in＝Ｉ・in−in＝Ｉ・_F＋（ａ−１）Ｋ・
ａＩ・_2L−（ａ−１）Ｋ・ａ_2L ＝Ｉ・_F＋（ａ−１）Ｋ・ａ△Ｉ・_2L≒Ｉ・_F…
…(10) 但し、△Ｉ・_2L＝Ｉ・_2L−_2L≒０となる。この(10)式の演算値△Ｉ・inは負荷電流の逆
相成分及び零相循環電流成分が除外され、故障電
流成分のみとなる。この電流△Ｉ・inを新ためて継
電器入力電流とすれば地絡回路を判別できる。Ｋ・
ａ＝1.73∠30°とすると△Ｉ・inは逆相差電流の変化
分となる。またＫ・ａ＝０とする△Ｉ・inは零相差電流の変化
分となるが、いづれもリレー誤差電流はなくリレ
ー性能は変わりない。以上の方法で相手端先行しや断前まで（外部故
障も含む）は負荷電流の逆相成分の影響を除外す
ることができる。ところが、第３図Ｂに示すよう
に、相手端が先行しや断した場合、自端での差回
路に生じる負荷電流は大きくなり、自端での差電
流に現われる負荷電流逆相分の地絡故障発生前後
の変化物△Ｉ・_2Lが零とならずに(10)式中の（ａ−
１）Ｋ・ａ△Ｉ・_2Lが継電器入力電流に誤差電流分と
て残る。このため、相手端が先行しや断した後は
さらに次の方法によつて継電器入力電流を得る。その方法をわかりやすく説明するために、まず
第４図の平行２回線２端子系統を例にとる。負荷電流の力率が100％に近いと、１線地絡時
の地絡相を基準とした負荷電流の正相分Ｉ・_1Lと故
障電流成分Ｉ・_Fとの位相関係は同相又は逆位相と
なる（第５図Ａ〜Ｃを参照）。第４図および第５図Ａ〜Ｃにおいて、実線矢印
は先行トリツプ前の負荷正相電流の方向、鎖線矢
印は先行トリツプ後の負荷正相電流の変化方向を
示し、は１線地絡故障時に回線間差電流（回線
３１と回線３２の零相電流の差）に表わせる故障
電流方向と同一である正方向を示すはその反対
方向である逆方向を示す。また、−ｎ△I_1Lはリレ
ー入力電流に印加する負荷正相電流の変化分を示
し、ｎは定数である。第４図に示すように回線３１が電気所S₂近傍Ｆ
点で故障するとまず電気所S₂の回線選択継電器が
動作してしや断器４１２が先行トリツプする。す
ると第５図Ａ〜Ｃに示すように電気所S₂は受け潮
流なので、電気所S₁の回線間差電流に生じる故障
電流I_Fと同じく回線間差電流に生じる負荷正相電
流の変化物ΔＩ・_1Lは反対方向となるが、ΔＩ・_1Lを
検出してリレー入力電流として故障電流と同一方
向に印加すれば、負荷電流の正相分に対する逆相
分の含有率は通常５〜10％以下なので、負荷電流
の逆相分に影響されることなく地絡回線を選択す
ることができる。平行４回線３端子系統で、１端
子が先行トリツプした場合に残り端子の故障回線
である回線選択リレー設置回線の差電流に生じる
負荷正相電流の変化方向及び和電流に生じる負荷
正相電流の変化方向を求めた結果が第４表〜第８
表である。また以下の各表において、正相電流は地絡相を
基準とした方向（以下同じ）、差電流に表われる
故障電流と同一方向を、反対方向をとする。
ただし、負荷の力率は１とする（以下同じ）。第
４表から第６表は表中に示すようにそれぞれ第６
図Ａ〜第６図Ｅに対応するものである。第６図Ａ〜Ｅにおいて、母線から送電線側へ変
化するものを内方向、その反対方向を外方向とす
る（以下同じ）。[Table] Next, the zero-sequence difference current I・od at the time of a one-wire ground fault is the sum of the fault current I・_F and the zero-sequence circulating current I・oc, I・od=I・_F +I・oc ……( 6) In order to compensate for the zero-sequence circulating current I.oc included in the zero-sequence difference current I.od, the following calculation is performed using the above-mentioned calculated value A of the zero-sequence circulating current, and the relay input I.in is demand. I・in=I・od−A=I・_F +I・oc−{I〓
^es _pc + (a-1)K・aI・_2L } =I・_F −(a-1)K・aI・_2L +ΔI
・co……(7) However, ΔI・oc=I・oc−I〓 ^es _pc ΔI・oc: Error I・oc In this conventional method, the load current has a negative phase component I・_2L and an error I・oc becomes the relay error current and the fault current I/ _F component is impaired. However, the error I・oc
ΔIoc can be made sufficiently small to be practically acceptable by setting the values of the constants K·a, K·b, and K·c as described later. However, there is a problem in that the sensitivity of the ground fault line selection relay decreases due to the relay error current due to the negative phase component _I.2L of the load current. The present invention is not affected by the circulating current induced by the load current and the negative phase component of the load current.
The purpose of this invention is to provide a line selection relay for a high-resistance grounded parallel four-line three-terminal system, and its principle will be explained below by taking a three-terminal system as an example. (First Embodiment) A ground fault line selection relay determines a faulty line based on the magnitude and direction of zero-sequence difference current between lines at its own end (hereinafter referred to as zero-sequence difference current). For this reason,
In the case of a fault near the other end, there is no zero-sequence difference current at the own end until the other end takes the lead and then breaks, resulting in a so-called series trip in which the other end leads and breaks and then the own end immediately breaks. FIGS. 3A, B, and C are diagrams showing an example of a series trip in a parallel four-line three-terminal system. Let the own end be electrical station _S1 . In the figure, 1 is the power supply, 2 is the neutral point grounding resistance NGR, 411~
444 is the bridge and disconnector, 62 to 66 are the mating end busbars 12
~16 shows the connected load. Figure A shows a case where a ground fault occurs at point F of the line 31 near the opposite end electrical station _S2 . In this case, the ground fault line selection relays of lines 31 and 32 are activated, and the disconnectors installed in line 31 of electric stations S ₁ , S ₂ , and S ₃ are tripped. ₁ and _S3 are close to zero, so the line selection relay cannot respond. Therefore, as shown in Fig. 3B, the breaker 4 at the other end
12 leads to the first break (or first trip)
do. When the breaker 412 opens, the zero-sequence difference current between its own end and the other end increases, but the zero-sequence difference current at the other end exceeds the setting value of the ground fault relay, and the zero-sequence difference current at the own end exceeds the ground fault relay's setting value. If the set value is not exceeded, as shown in FIG. 3C, the shear breaker 413 at the other mating end is ruptured (second trip). Thereafter, although not shown, the fault current at the own end increases, and the ground fault line selection relay of the own end electric station _S1 operates, causing the breaker 411 to trip and the fault to be removed (third trip). Taking such series trip into consideration and excluding the influence of the negative phase component of the load current, first obtain the relay input current by the following method until the other end is ahead or disconnected. 1, which is the load of electrical stations S ₅ and S ₆ shown in Figure 3.
If the negative phase component of the load current that appears in the differential current due to the T-branch load of the line power reception when the system is healthy is I・_2L , then the relay input current I・in (hereinafter referred to as I・in is the relay input current for which the zero-sequence circulating current is completely compensated, and ΔI・_0c = 0.)
From the above equation (7), _io = (a-1) K・a・_2L (8). (However, _io and _2L mean the amounts when the system is healthy, and are the opposite phase components of the relay input current and load current before the a-phase ground fault, respectively.) Next, the other end takes precedence from the a-phase ground fault occurrence. From equation (7), the input current I.in before it is cut off is I.in = _I.F + (a-1 _{) K.a.I.2L} ₍ 9). It is impossible to measure the negative phase component of the load current only from the current at the own end during a one-wire ground fault, but
In a high-resistance grounding system, the line voltage during a one-line ground fault is almost the same as when the system is healthy, so assuming that the magnitude of the T-branch load does not change before and after the occurrence of a ground fault, The negative phase component appearing in the differential current also remains at a nearly constant value before and after the ground fault (I _2L = _2L ). Therefore, the relay input current I・before and after the occurrence of a ground fault
If the change in in is ΔI・in, then from equations (8) and (9), △I・in=I・in−in=I・_F +(a−1)K・
aI・_2L −(a−1)K・a _2L =I・_F +(a−1)K・a△I・_2L ≒I・_F …
…(10) However, △I・_2L = I・_2L − _2L ≒0. The calculated value ΔI·in of equation (10) excludes the negative phase component and zero-sequence circulating current component of the load current, and contains only the fault current component. If this current ΔI·in is newly set as the relay input current, a ground fault circuit can be determined. K.
When a=1.73∠30°, △I·in is the change in the negative phase difference current. Furthermore, ΔI·in when K·a=0 is a change in the zero-sequence difference current, but there is no relay error current in either case, and the relay performance remains unchanged. By the above method, it is possible to exclude the influence of the negative phase component of the load current until the other end is ahead or disconnected (including external failures). However, as shown in Figure 3B, if the other end leads or breaks, the load current generated in the difference circuit at its own end increases, and the load current that appears in the difference current at its own end has an opposite phase to the ground. Since the variable △I・_2L before and after the occurrence of the circuit fault does not become zero, (a-
1) K・a△I・_2L remains as an error current in the relay input current. For this reason, after the other end has preceded or broken, the relay input current is further obtained by the following method. To explain this method in an easy-to-understand manner, we will first take the parallel two-line, two-terminal system shown in FIG. 4 as an example. When the power factor of the load current is close to 100%, the phase relationship between the positive phase component I・_1L of the load current and the fault current component I・_F with respect to the ground fault phase at the time of a one-line ground fault is in-phase or anti-phase. (See FIGS. 5A to 5C). 4 and 5A to 5C, the solid line arrow indicates the direction of the load positive sequence current before the preceding trip, the chain line arrow indicates the direction of change in the load positive sequence current after the preceding trip, and the arrow indicates the direction of change in the load positive sequence current after the preceding trip. The positive direction, which is the same direction as the fault current direction expressed by the line difference current (difference between the zero-sequence currents of the lines 31 and 32), indicates the opposite direction, which is the opposite direction. Moreover, -nΔI _1L indicates a change in the load positive-sequence current applied to the relay input current, and n is a constant. As shown in Fig. 4, the line 31 is located near electric station _S2 F.
When a failure occurs at a point, the line selection relay at the electrical station _S2 operates first, causing the breaker 412 to trip in advance. Then, as shown in Fig. 5 A to C, since electric power station S ₂ is receiving power flow, the fault current I _F that occurs in the line difference current of electric station S ₁ is a change in the load positive sequence current that occurs in the line difference current. ΔI・_1L is in the opposite direction, but if ΔI・_1L is detected and applied as a relay input current in the same direction as the fault current, the content ratio of the negative phase to the positive phase of the load current is usually 5 to 10%. Since it is as follows, the ground fault line can be selected without being affected by the negative phase component of the load current. In a parallel 4-line 3-terminal system, if one terminal trips in advance, the direction of change in the load positive sequence current that occurs in the differential current of the line selection relay installed line, which is the faulty line of the remaining terminal, and the load positive sequence current that occurs in the sum current. The results of determining the direction of change are shown in Tables 4 to 8.
It is a table. Furthermore, in each table below, the positive sequence current is in the direction with respect to the ground fault phase (the same applies hereinafter), the same direction as the fault current appearing in the difference current, and the opposite direction.
However, the power factor of the load shall be 1 (the same applies hereinafter). Tables 4 to 6 are the 6th table, respectively, as shown in the table.
This corresponds to FIGS. A to 6E. In FIGS. 6A to 6E, the direction that changes from the bus bar to the power transmission line side is defined as the inward direction, and the opposite direction is defined as the outward direction (the same applies hereinafter).

【表】【table】

【表】但し、健全回線である回線選択リレー設置回線
の差電流に生じる故障電流及び負荷正相電流の変
化分は零となるので省略した。そのうち第５表は
電気所S₂で故障回線に受け潮流で先行トリツプさ
れたケースであるが、残り端子の回線選択リレー
設置回線の差電流に表わされる負荷正相電流の変
化分とその方向及び和電流に表われる負荷正相電
流の変化分とその方向は第９表のようになる。[Table] However, the changes in fault current and load positive-sequence current that occur in the differential current of a healthy line with a line selection relay installed are zero, so they are omitted. Of these, Table 5 shows a case where a fault line was tripped in advance due to the power flow received by the faulty line at electric station _S2 , and shows the change in the load positive sequence current expressed by the difference current of the line where the line selection relay of the remaining terminal is installed, its direction, and Table 9 shows the amount of change in the load positive sequence current that appears in the sum current and its direction.

【表】次にさらにもう１端子先行しや断して１端子の
み残り端子になつた場合の回線選択リレー設置回
路の差電流に表われる負荷正相電流の変化方向及
び和電流に表われる負荷正相電流の変化方向を求
めた結果が第10表〜12表である。[Table] Load shown in the differential current of the line selection relay installation circuit when one more terminal is preceded or disconnected and only one terminal remains Tables 10 to 12 show the results of determining the direction of change in the positive sequence current.

【表】【table】

【表】以上から、先行トリツプを検出すると回線選択
継電器を正しく動作させるために、零相循環電流
を補償した零相差電流(7)式に対して、差電流に表
われる負荷性相電流の変化分ΔＩ・_1Lの印加方向
を、和電流の変化方向に応じて第13表の通りとす
る。[Table] From the above, in order to operate the line selection relay correctly when a preceding trip is detected, the zero-sequence difference current (7) that compensates for the zero-sequence circulating current is The direction of application of the minute ΔI· _1L is as shown in Table 13 depending on the direction of change in the sum current.

【表】また、地絡前後の変化分をとつたリレー入力電
流である(10)式に対して上記のΔＩ・_1Lを和電流の変
化方向に応じて印加する方法もあるが効果は上記
の方式のほうが大である。負荷電流の逆相分Ｉ・_2Lによるリレー誤差電流に
よる影響を受けないようにするために、差電流に
表れる負荷正相電流の変化分△Ｉ・_1Lをリレー入力
電流(7)式に対して、回線選択リレー設置回線の和
電流ΣAＩ・_1Lの変化方向に応じて、下記の(11)式に
示すように又はの方向にして印加する。但
し、電気所S₃及びS₄の回線選択リレーについては
ΣAＩ・_1Lの変化方向は検出せずに常時△Ｉ・_1Lを
方向に印加する。Ｉ・in＝Ｉ・od−Ａ±ｎ△Ｉ・_1L＝Ｉ・
Ｆ−（１−ａ）Ｋ・ａＩ・_2L±ｎ△Ｉ・_1L……(11) すなわち、負荷電流の正相成分Ｉ・_1Lに対する逆
相成分Ｉ・_2Lの含有率α＝｜Ｉ・_2L｜／｜Ｉ・_1L｜は、
一般に最大５％程度であり、例えばＫ・ａの大きさ
は最大でも第２表より3.71なので｜（１−ａ）Ｋ・ａＩ・_2L｜＝1.73×3.71×
0.05｜Ｉ・_1L｜＝0.32｜Ｉ・_1L｜となり、ｎを１とすれば、｜△Ｉ・_1L｜≫｜（１−ａ）Ｋ・ａＩ・_2L｜＝0.32｜Ｉ
・_1L
｜が成立する。また、負荷の力率が１とすると−Ｖ・
ｏと△Ｉ・_1Lとの位相は等しい。力率は一般的に
0.8以上である。この場合でも−Ｖ・ｏとΔＩ・_1Lと
の位相差は37°なので、事故回線を正しく選択で
きることになる。差電流に表れる負荷正相電流の変化分を検出す
る１例を示すと、第14表通り故障電流成分を含ま
ない健全相電流より検出する。[Table] There is also a method of applying the above ΔI・_1L to equation (10), which is the relay input current that takes the change before and after the ground fault, depending on the direction of change in the sum current, but the effect is as follows. The method is more important. In order to avoid being affected by the relay error current due to the negative-sequence component I・_2L of the load current, the change in the load positive-sequence current △I・_1L that appears in the difference current is expressed as the relay input current by equation (7). , depending on the direction of change of the sum current ΣAI· _1L of the line where the line selection relay is installed, apply it in the or direction as shown in equation (11) below. However, the line selection relays at electric stations _S3 and _S4 do not detect the direction of change in ΣAI・_1L , but always apply ΔI・_1L in the direction. I・in=I・od−A±n△I・_1L =I・
F-(1-a) K・aI・_2L ±n△I・_1L ……(11) In other words, the content rate α of the negative phase component I・_2L with respect to the positive phase component I・_1L of the load current = |I・_2L ｜／｜I・_1L ｜is,
Generally, it is about 5% at most, and for example, the maximum size of K・a is 3.71 from Table 2, so |(1-a) K・aI・_2L |=1.73×3.71×
0.05｜I・_1L ｜=0.32｜I・_1L ｜, and if n is 1, then ｜△I・_1L ｜≫｜(1-a)K・aI・_2L ｜=0.32｜I
・_1L
| holds true. Also, if the power factor of the load is 1, -V・
The phases of o and △I・_1L are equal. The power factor is generally
It is 0.8 or more. Even in this case, since the phase difference between -V·o and ΔI· _1L is 37°, the faulty line can be selected correctly. An example of detecting the change in the load positive sequence current that appears in the differential current is as shown in Table 14, where it is detected from the healthy phase current that does not include the fault current component.

【表】【table】

Claims

【特許請求の範囲】１高抵抗接地系平行多回線における回線間差電
流の２つの健全相の差電流から正相分を除去し係
数を乗じた値を回線間零相差電流から差し引く第
１の手段と、回線間差電流に生じる正相電流の変
化分を求める第２の手段と、回線間和電流に生じ
る和電流の変化方向を求める第３の手段を有し、
地絡故障発生から最初にトリツプするまでは前記
第１の手段によつて得られた値に対して地絡故障
発生前後の変化分と極性量とによつて地絡回線を
選択する第１の選択手段と、前記最初のトリツプ
以後は前記第１の手段によつて得られた値と前記
第３の手段によつて求められた変化方向に応じて
前記第２の手段によつて求められ値との和または
差をとつた値と極性量とによつて地絡回線を選択
する第２の選択手段とによつて構成したことを特
徴とする平行多回線系統用地絡回線選択継電器。２最初のトリツプ以降は、一定時間継電器の動
作をロツクして第１の手段によつて得られた値
と、第２の手段によつて求められた値との和と極
性量とによつて地絡回線を選択することを特徴と
した特許請求の範囲第１項記載の平行多回線系統
用地絡回線選択継電器。３第１の手段で求める値を逆相差電流の地絡前
後の変化分としたことを特徴とした特許請求の範
囲第１項記載の平行多回線系統用地絡回線選択継
電器。４第１の手段で求める値を零相差電流の地絡前
後の変化分としたことを特徴とした特許請求の範
囲第１項記載の平行多回線系統用回線選択継電
器。５第１の手段で求める値を逆相または零相差電
流としたことを特徴とした特許請求の範囲第１項
記載の平行多回線系統用地絡回線選択継電器。[Scope of Claims] 1. A first method of removing the positive phase component from the difference current between two healthy phases of the inter-line difference current in a high-resistance grounding system parallel multi-circuit, and subtracting the value obtained by multiplying by a coefficient from the inter-line zero-sequence difference current. means, second means for determining a change in positive sequence current occurring in the inter-line difference current, and third means for determining the direction of change in the sum current occurring in the inter-line sum current,
From the occurrence of a ground fault fault until the first trip, the first method selects a ground fault line based on the amount of change and polarity before and after the occurrence of a ground fault fault with respect to the value obtained by the first means. a selection means, and after the first trip, a value determined by the second means according to the value obtained by the first means and the direction of change determined by the third means; 1. A ground fault line selection relay for a parallel multi-line system, characterized in that the relay comprises a second selection means for selecting a ground fault line based on a value obtained by taking the sum or difference between the two and a polarity amount. 2 After the first trip, the operation of the relay is locked for a certain period of time and the value obtained by the first means is determined by the sum of the value obtained by the second means and the polarity amount. A ground fault line selection relay for a parallel multi-circuit system according to claim 1, characterized in that a ground fault line is selected. 3. A ground fault line selection relay for a parallel multi-circuit system according to claim 1, wherein the value obtained by the first means is the change in the negative phase difference current before and after the ground fault. 4. A line selection relay for a parallel multi-line system according to claim 1, wherein the value obtained by the first means is the change in zero-sequence difference current before and after the ground fault. 5. A ground fault line selection relay for a parallel multi-circuit system according to claim 1, wherein the value determined by the first means is a negative phase or zero phase difference current.