JP2010268658A - Accident phase selector - Google Patents
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本発明は、直接接地系電力系統における送電線の事故相選別装置に関するものである。 The present invention relates to an accident phase selection device for a transmission line in a direct grounding power system.
送電線上の事故を検出するために距離リレーが用いられ、送電線の事故点までの距離を求めるためには故障点標定装置が用いられる。この場合の標定方法としては、例えば事故相選別を行い、その選別相に応じたインピーダンス計測により事故点までの距離を求める方法がある。 A distance relay is used to detect an accident on the transmission line, and a fault location device is used to determine the distance to the accident point on the transmission line. As an orientation method in this case, for example, there is a method of selecting the accident phase and obtaining the distance to the accident point by measuring impedance according to the selected phase.
従来、このような距離リレーや故障点標定装置に用いる事故相選別装置においては、各線間電流の事故分電流とその事故分電流の最大値との比をそれぞれ求め、これらの比の1つがある一定値より小さい場合に1線地絡事故とし、各相の変化分電流が最大となる相を事故相とするものがある。(例えば、特許文献1参照)。 Conventionally, in an accident phase selection device used for such a distance relay or fault location device, the ratio between the fault current of each line current and the maximum value of the fault current is obtained, and there is one of these ratios. There are cases where a one-line ground fault occurs when the value is smaller than a certain value, and the phase where the change current of each phase is maximum is the fault phase. (For example, refer to Patent Document 1).
上記のような事故相選別装置においては、事故分電流を事故後の相電流瞬時値から事故前の潮流電流瞬時値の差としているため、現時点の電流瞬時値とそれ以前の同位相の電流瞬時値が必要である。しかしながら、事故相選別装置の入力電流は定格周波数の整数倍の周波数でサンプリングするため、入力電流の系統周波数が定格周波数から変動すると、系統事故による電流変化が無い場合であっても、サンプリング時の入力電流と差分を採るそれ以前の電流との間に位相差が生じるため、誤差差分電流が発生することになり、1線地絡事故としての事故相選別を誤る恐れがあった。 In the accident phase selection device as described above, since the accident current is the difference between the instantaneous current value after the accident and the instantaneous current value before the accident, the current instantaneous value at the current time and the current instantaneous current in the previous phase are the same. A value is required. However, since the input current of the accident phase selection device is sampled at an integer multiple of the rated frequency, if the system frequency of the input current fluctuates from the rated frequency, even if there is no current change due to a system fault, Since there is a phase difference between the input current and the current before taking the difference, an error difference current is generated, and there is a risk of erroneous phase selection as a one-wire ground fault.
本発明は上記のような問題点を解決するためになされたもので、入力電流の系統周波数が変動しても1線地絡事故としての事故相を正確に選別できる事故相選別装置を得ることを目的とする。 The present invention has been made to solve the above-described problems, and provides an accident phase selection device capable of accurately selecting an accident phase as a one-wire ground fault even if the system frequency of the input current fluctuates. With the goal.
本発明に係る事故相選別装置は、送電線に流れる電流値を基に送電線事故時の事故相を選別する事故相選別装置において、検出タイミングの異なる相電流の差分を各相毎に算出する差分相電流算出手段と、差分相電流算出手段で得られた各相の差分相電流に基づいて差分線間電流をそれぞれ算出する差分線間電流演算手段と、差分線間電流演算手段で得られた各相間の差分線間電流のスカラー値をそれぞれ算出するスカラー値算出手段と、各相間毎に現時点における差分線間電流のスカラー値からそれ以前における差分線間電流のスカラー値を減算する差分スカラー値演算手段と、各相間の差分スカラー値のうち1つだけが所定値未満のとき1線地絡事故としての事故相を判定する判定手段とを備えたものである。 The accident phase selection apparatus according to the present invention calculates a difference between phase currents having different detection timings for each phase in an accident phase selection apparatus that selects an accident phase at the time of a transmission line accident based on a current value flowing through a transmission line. Obtained by the differential phase current calculating means, the differential line current calculating means for calculating the differential line current based on the differential phase current of each phase obtained by the differential phase current calculating means, and the differential line current calculating means. Scalar value calculation means for calculating the scalar value of the difference line current between each phase, and the difference scalar that subtracts the scalar value of the current difference line current from the current difference line current scalar value for each phase. And a value calculating means and a determining means for determining an accident phase as a one-line ground fault when only one of the differential scalar values between the phases is less than a predetermined value.
本発明によれば、各相における検出タイミングの異なる相電流の差分に基づいて各相間の差分線間電流のスカラー値を求め、現時点におけるスカラー値からそれ以前におけるスカラー値を減算して差分スカラー値を算出し、差分スカラー値のうち1つだけが所定値未満のとき1線地絡事故としての事故相を判定することにより、入力電流の系統周波数が変動しても1線地絡事故の事故相を正確に選別できる。 According to the present invention, a scalar value of a difference line current between each phase is obtained based on a difference between phase currents having different detection timings in each phase, and a scalar value obtained by subtracting the previous scalar value from the current scalar value is obtained. If only one of the difference scalar values is less than the predetermined value, the accident phase as a one-line ground fault is judged, so even if the system frequency of the input current fluctuates, the one-line ground fault accident The phase can be accurately selected.
実施の形態1.
本発明を実施するための実施の形態1における事故相選別装置1を図1ないし図3を用いて説明する。図1において、事故相選別装置1は距離リレー2の一部であるCPU3に3相の送電線からの入力データを所定時間保持する入力データ保持部101と、事故相選別を行う事故相選別部102とから構成されている。また、CPU3は事故点が距離リレー2の保護区間であることを判定する距離要素演算部31と、距離リレー2の保護区間を記憶しておく整定部(図示しない)と、事故相選別部102及び距離要素演算部31の結果に基づいて事故相の送電線遮断信号を生成するロジック演算部32を備えている。
なお、ここでは事故相選別装置1をCPU3で構成したが、フリップフロップ等で形成した入力データ保持部及びロジック回路等で形成した事故相選別部のように一部または全部をハードウエアで構成してもよい。また、距離リレー2は他の直接接地系電力系統に適用される保護リレーであってもよい。
An accident
Although the accident
距離リレー2はCPU3の他に、各相の送電線7に設けられたCT(Current Transformer)9及びPT(Potential Transformer)10にそれぞれ接続され、3相の送電線7から入力される電流及び電圧のアナログインタフェースとなるAI回路4と、アナログ入力をデジタルデータに変換するA/D変換回路5と、CPU3の演算結果を信号線11を介して各相の送電線に設けられた遮断器8へ出力する出力回路6とで構成されている。
In addition to the
次に、動作について説明する。
送電線7のアナログ電流及びアナログ電圧は距離リレー2に入力されると、AI回路4を介してA/D変換回路5に入力され、サンプリングによりデジタルデータに変換された後にCPU3に出力される。CPU3に入力されたデジタルデータは入力データ保持部101において適切な期間保持され、距離要素演算部31及び事故相選別部102にそれぞれ出力される。距離要素演算部31は入力データ保持部101からのデータに基づいて事故点までの距離を算出し、整定部に記憶された距離リレー2の保護区間内であればロジック演算部32へ結果を出力する。
Next, the operation will be described.
When the analog current and analog voltage of the transmission line 7 are input to the
一方、事故相選別部102では入力データ保持部101からのデータに基づいて電力系統に発生した事故の種類と事故相を判定し、結果をロジック演算部32へ出力する。ロジック演算部32は事故相における事故点までの距離が距離リレー2の保護区間内であるときに事故と判定し、出力回路6はこの判定結果に基づいて該当する相の遮断器8へ遮断信号を出力する。
On the other hand, the accident phase selection unit 102 determines the type and accident phase of the accident that has occurred in the power system based on the data from the input data holding unit 101, and outputs the result to the
ここで、事故相選別装置1における事故の種類及び事故相の判定方法について図2を用いて説明する。ステップS11では、各相において相電流を系統周波数のN周期分(Nは整数)の値を保持し、ステップS12では、各相において現時点の相電流と(N−1)個前の相電流の差分をそれぞれ算出する。負荷電流に変化が無く、系統周波数の変動もない場合には差分相電流が3相共に零となる。
Here, an accident type and an accident phase determination method in the accident
ステップS13では、各相の差分相電流に基づいて各相間の差分線間電流をそれぞれ算出する。1相地絡事故時の健全相2相に含まれる零相電流は健全相2相の相電流に等しく含まれるため、線間電流を算出することで地絡事故発生時における健全相2相の零相電流を相殺できる。 In step S13, the differential line current between each phase is calculated based on the differential phase current of each phase. The zero-phase current contained in the two phases of the healthy phase at the time of the one-phase ground fault is equal to the phase current of the two phases of the healthy phase. Therefore, by calculating the line current, Zero phase current can be offset.
ステップS14では、各相間の差分線間電流からそれぞれのスカラー値(振幅値)を算出し、定格周波数のP倍(Pは整数)でサンプリングしたスカラー値M個分(Mは整数、かつM<N*P)の値を保持する。スカラー値を保持する最低期間を系統電流の位相差π/2相当とすると、差分線間電流のスカラー値は三平方の定理により次式で求められる。ただし、IAB(t)は時刻tにおけるA−B相間の差分線間電流の瞬時値とし、式の左辺はスカラー値を示すものとする。B−C相間及びC−A相間についても同様に求めることができる。 In step S14, each scalar value (amplitude value) is calculated from the differential line current between the phases, and M scalar values (M is an integer and M <) are sampled at P times the rated frequency (P is an integer). N * P) is held. Assuming that the minimum period for holding the scalar value is equivalent to the phase difference π / 2 of the system current, the scalar value of the difference line current can be obtained by the following equation using the three-square theorem. However, I AB (t) is an instantaneous value of the differential line-to-line current between phases A and B at time t, and the left side of the equation represents a scalar value. The same can be obtained for the B-C phase and the C-A phase.
ステップS15では、各相間において現時点における差分線間電流のスカラー値から(M−1)個前の差分線間電流のスカラー値を減算して差分スカラー値をそれぞれ求める。入力電流の系統周波数は変動するのに対し、サンプリング周波数は定格周波数の整数倍に固定されているため負荷電流が一定の場合にも差分相電流が発生する場合があるが、ステップS15を踏むことで、負荷電流が一定の場合における前記スカラー値の差分は零となり、周波数変動による誤差を相殺できる。 In step S15, a difference scalar value is obtained by subtracting the scalar value of the (M-1) previous difference line current from the current difference line current scalar value between the phases. While the system frequency of the input current varies, the sampling frequency is fixed to an integral multiple of the rated frequency, so a differential phase current may be generated even when the load current is constant, but step S15 should be taken. Therefore, when the load current is constant, the difference between the scalar values becomes zero, and the error due to the frequency fluctuation can be offset.
ステップS16では、各相間の差分スカラー値を1線地絡事故における差分スカラー値と事故相の関係を示す図3に基づいて1線地絡事故か否かの判定及び事故相の判定を行う。第1の判定基準値をk1、第2の判定基準値をk2とすると、各相間の差分スカラー値のうち1つだけがk1未満で、かつ他の2つの差分スカラー値が共にk2より大きい場合に1線地絡事故とし、差分相電流の最大相すなわち相間の差分スカラー値がk1未満となる2相以外を事故相と判定する。 In step S16, the difference scalar value between each phase is determined based on FIG. 3 showing the relationship between the difference scalar value in the one-line ground fault and the accident phase, and the accident phase is determined. When the first determination reference value is k1 and the second determination reference value is k2, only one of the difference scalar values between the phases is less than k1, and the other two difference scalar values are both greater than k2. In this case, a one-line ground fault is determined, and the maximum phase of the differential phase current, that is, the phase other than the two phases where the differential scalar value between the phases is less than k1 is determined as the accident phase.
ステップS17では、ステップS16において1線地絡事故でない場合に、事故なし、あるいは2線事故、3線事故の判定をし、2線事故または3線事故のときは事故相を選別する。各相間の差分スカラー値が全てk2より大きいときは2線事故または3線事故、全てk1より小さいときは事故なしとなる。それ以外の場合は事故相判定が困難な状態であり、3線事故と扱っても良い。例えば2線事故で1相電流がk2より小さく、もう1相がk2より大きいケースが相当し、その場合は距離要素演算部31の結果が誤出力しないと考えられるので、ロジック演算部32の出力は距離リレーとしての出力には影響が無く、問題とならないからである。 In step S17, if it is not a one-line ground fault in step S16, it is determined that there is no accident, a two-wire accident or a three-wire accident, and an accident phase is selected in the case of a two-wire accident or a three-wire accident. When the differential scalar values between the phases are all greater than k2, there is a 2-wire accident or 3-wire accident, and when all are less than k1, there is no accident. In other cases, it is difficult to determine the accident phase, and it may be handled as a 3-wire accident. For example, a case where a one-phase current is smaller than k2 and the other phase is larger than k2 in a two-wire accident corresponds to a case where the result of the distance element calculation unit 31 is not likely to be erroneously output. This is because the output as a distance relay is not affected and does not cause a problem.
2線事故または3線事故の場合、3相の相電圧のうち最大振幅となる相が健全相、他の2相が事故相となる。事故相は線間電流が最大となる2相として判定することもできるが、各相間のアーク抵抗が不平衡の場合に健全相を含む線間電流が2相とも事故相の線間電流より大きくなり、誤判定する恐れがある。これに対し、相電圧による方法においては、健全相における相電圧の振幅は変化が小さいため事故相における相電圧よりも必ず大きくなり正確に判定できる。なお、3線事故の場合は2線事故と同様に判定していずれか2相を事故相とする。
また、2線事故の場合、事故相である2相のインピーダンスが他の健全相より必ず小さくなるため、事故相の判定は各相の相電圧の代わりに各相間のインピーダンスを求め、最小インピーダンスとなる2相を事故相としてもよい。
In the case of a two-wire accident or a three-wire accident, the phase having the maximum amplitude among the three-phase voltages is the healthy phase, and the other two phases are the accident phases. The accident phase can be determined as the two phases with the maximum line current, but when the arc resistance between the phases is unbalanced, the line current including the healthy phase is larger than the line current of the accident phase in both phases. There is a risk of misjudgment. On the other hand, in the method using the phase voltage, the amplitude of the phase voltage in the healthy phase has a small change, so that it is always larger than the phase voltage in the accident phase and can be accurately determined. In the case of a 3-wire accident, it is determined in the same manner as the 2-wire accident, and one of the two phases is designated as the accident phase.
Also, in the case of a two-wire accident, the impedance of the two phases, which are the accident phases, is always smaller than the other healthy phases, so the judgment of the accident phase is the impedance between each phase instead of the phase voltage of each phase. These two phases may be accident phases.
この実施の形態によれば、各相における検出タイミングの異なる相電流を入力データ保持部101にて所定期間保持し、この相電流の差分に基づいて事故相選別部102において各相間の差分線間電流のスカラー値を求め、現時点におけるスカラー値からそれ以前におけるスカラー値を減算して差分スカラー値を算出し、差分スカラー値のうち1つだけが所定値未満のとき1線地絡事故としての事故相を判定することにより、入力電流の系統周波数が変動しても負荷電流の誤差を相殺して1線地絡事故の事故相を正確に選別できる。 According to this embodiment, phase currents having different detection timings in each phase are held in the input data holding unit 101 for a predetermined period, and the accident phase selection unit 102 determines the difference between the difference lines between the phases based on the phase current difference. Calculate the scalar value of the current, subtract the previous scalar value from the current scalar value, calculate the difference scalar value, and if only one of the difference scalar values is less than the predetermined value, an accident as a one-line ground fault By determining the phase, even if the system frequency of the input current fluctuates, the error of the load current can be canceled and the accident phase of the one-wire ground fault can be accurately selected.
また、各相間の差分スカラー値が全て所定値よりも大きいか判定することにより、1線地絡事故だけでなく2線事故または3線事故の事故相選別もできる。 Further, by determining whether the difference scalar values between the phases are all greater than the predetermined value, it is possible to select not only the 1-line ground fault but also the 2-line or 3-line accident phase.
また、差分スカラー値は現時点における差分線間電流のスカラー値から(M−1)個前の差分線間電流のスカラー値を減算することにより、事故発生前の差分線間電流のスカラー値が周波数変動の影響を受けても負荷電流の誤差を相殺して1線地絡事故の事故相を正確に選別できる。 Further, the difference scalar value is obtained by subtracting the (M−1) previous difference line current scalar value from the current difference line current scalar value, so that the difference line current scalar value before the occurrence of the accident becomes the frequency. Even under the influence of fluctuations, the error of the load current can be offset and the accident phase of the one-line ground fault can be accurately selected.
また、1線地絡事故の場合に差分相電流を用いることで事故相を容易に特定できる。 Moreover, the accident phase can be easily specified by using the differential phase current in the case of a one-wire ground fault.
また、各相間の差分スカラー値が全て所定値よりも大きいときに2線事故または3線事故として、3相の相電圧のうち最大振幅となる2相を事故相と判定することにより、アーク事故等で相間のアーク抵抗が不平衡になった場合でも信頼性の高い2線事故の事故相選別ができる。 Moreover, when the difference scalar values between the phases are all larger than the predetermined value, the two-phase accident or the three-wire accident is determined as the accident phase, and the two phases having the maximum amplitude among the three-phase phase voltages are determined. Even if the arc resistance between the phases becomes unbalanced, etc., it is possible to select the accident phase of the two-wire accident with high reliability.
また、2線事故または3線事故の場合に各相間のインピーダンスを求めて最小インピーダンスとなる2相を事故相と判定することにより、電圧だけでなく電流の影響も加味するため事故相選別の信頼性をさらに向上できる。 In addition, in the case of a two-wire accident or a three-wire accident, the impedance between each phase is obtained, and the two phases that are the minimum impedance are determined as the accident phase, so that not only the voltage but also the influence of the current is taken into account. The sex can be further improved.
実施の形態2.
上記実施の形態1では、入力電流の系統周波数が定格周波数から変動した場合における負荷電流の誤差を相殺するために現時点における差分線間電流のスカラー値から一定期間前の差分線間電流のスカラー値を減算している。実施の形態2では、図5に示すように一定期間前の差分線間電流のスカラー値の代わりに正常時の差分線間電流のスカラー値を減算する。
In the first embodiment, in order to cancel the load current error when the system frequency of the input current fluctuates from the rated frequency, the scalar value of the difference line current before a certain period from the scalar value of the difference line current at the present time. Is subtracted. In the second embodiment, as shown in FIG. 5, the scalar value of the difference line current at the normal time is subtracted instead of the scalar value of the difference line current before a certain period.
ステップS21では、各相において相電流を系統周波数のN周期分(Nは整数)の値を保持し、ステップS22では、各相において現時点の相電流と(N−1)個前の相電流の差分をそれぞれ算出する。
ステップS23では、各相の差分相電流に基づいて各相間の差分線間電流をそれぞれ算出し、定格周波数のP倍(Pは整数)でサンプリングした値をスカラー値換算したL個分(Lは整数、かつL≒P〜2P程度)の値を保持する。ただしスカラー値の保持期間は少なくとも系統電流の位相差π/2相当とする。
ステップS24では、各相間の差分線間電流からそれぞれのスカラー値を算出する。
In step S21, the phase current is held for each period of N periods of the system frequency (N is an integer) in each phase. In step S22, the current phase current and (N-1) previous phase currents in each phase. Each difference is calculated.
In step S23, the differential line current between each phase is calculated based on the differential phase current of each phase, and the values sampled at P times the rated frequency (P is an integer) are converted into scalar values (L is L). An integer and a value of L≈P to about 2P) are held. However, the scalar value holding period is at least equivalent to the phase difference π / 2 of the system current.
In step S24, each scalar value is calculated from the difference line current between each phase.
ステップS25では、各相間において現時点における差分線間電流のスカラー値から正常時の差分線間電流のスカラー値を減算して差分スカラー値をそれぞれ求める。前回のサイクルで事故無し(事故有フラグ=0)と判定していた場合、減算する正常時のスカラー値としてL個前の差分線間電流のスカラー値を用い、前回のサイクルで事故有り(事故有フラグ=1)と判定していた場合は、減算するスカラー値として正常時に記憶していた値(詳細は後述する)を用いる。
算出した各相間における差分スカラー値がすべて第1の判定基準値k1より小さい場合、事故有フラグは0のまま事故無しとして判定を終え、差分スカラー値のうちいずれか一つがk1より大きい場合、事故発生を検出して事故有フラグを1に更新すると共に、この時点よりL個前のスカラー値を正常時のスカラー値として記憶更新する。この記憶した正常時のスカラー値は、上述したように次サイクル以降の事故継続中、ステップS25においてL個前の差分線間電流のスカラー値の代わりに正常時のスカラー値として用いる。
ステップS26以降は実施の形態1と同様のため、説明を省略する。
In step S25, the difference scalar value is obtained by subtracting the scalar value of the difference line current at the normal time from the scalar value of the difference line current at the present time between the phases. If it was determined that there was no accident in the previous cycle (Accident flag = 0), the scalar value of the L previous difference line current was used as the normal value to be subtracted, and there was an accident in the previous cycle (accident) If it is determined that the presence flag = 1), the value stored in the normal state (details will be described later) is used as the scalar value to be subtracted.
When the calculated difference scalar values between the phases are all smaller than the first determination reference value k1, the determination is made that there is no accident with the accident flag remaining at 0, and if any one of the difference scalar values is greater than k1, an accident occurs. The occurrence is detected, the accident flag is updated to 1, and the scalar value L before this time is stored and updated as the normal scalar value. The stored normal scalar value is used as a normal scalar value instead of the L previous difference line current scalar value in step S25 during the accident continuing from the next cycle as described above.
Since step S26 and subsequent steps are the same as in the first embodiment, description thereof is omitted.
この実施の形態によれば、各相における差分相電流に基づいて各相間の差分線間電流のスカラー値を求め、現時点におけるスカラー値からそれ以前におけるスカラー値を減算して差分スカラー値を算出し、差分スカラー値のうち1つだけが所定値未満のとき1線地絡事故としての事故相を判定することにより、入力電流の系統周波数が変動しても負荷電流の誤差を相殺して1線地絡事故の事故相を正確に選別できる。 According to this embodiment, a scalar value of a difference line current between each phase is obtained based on a difference phase current in each phase, and a difference scalar value is calculated by subtracting the previous scalar value from the current scalar value. When only one of the difference scalar values is less than the predetermined value, the fault phase as a one-line ground fault is judged to cancel the load current error even if the system frequency of the input current fluctuates. It is possible to accurately select the accident phase of the ground fault.
また、差分スカラー値のいずれか1つが所定値よりも大きいときに事故発生を検出し、事故発生を検出した時点より一定時間前のスカラー値を記憶し、事故継続中は現時点におけるスカラー値から記憶した正常時のスカラー値を減算することにより、緩やかな周波数変動による負荷電流の誤差を軽減できる。 Also, the occurrence of an accident is detected when any one of the differential scalar values is greater than a predetermined value, the scalar value is stored for a certain time before the occurrence of the accident, and is stored from the current scalar value during the accident. By subtracting the normal scalar value, the load current error due to the gradual frequency fluctuation can be reduced.
また、1線地絡事故の場合に差分相電流を用いることで事故相を容易に特定できる。 Moreover, the accident phase can be easily specified by using the differential phase current in the case of a one-wire ground fault.
また、2線事故及び3線事故については実施の形態1と同様の効果を得る。 Further, the effects similar to those of the first embodiment are obtained for the 2-wire accident and the 3-wire accident.
実施の形態3.
上記実施の形態1及び実施の形態2では、入力電流の系統周波数が定格周波数から変動した場合における負荷電流の誤差を相殺するために現時点における差分線間電流のスカラー値からそれ以前の差分線間電流のスカラー値を減算している。実施の形態3では、図6に示すようにスカラー値算出後に減算する代わりに、各相において現時点及び一定時間前における相電流の位相差θを求め、現時点の相電流から一定時間前の相電流を位相差θ分だけ補正した値を減算する。
In the first embodiment and the second embodiment, in order to cancel the load current error when the system frequency of the input current fluctuates from the rated frequency, the difference between the current difference line current scalar value and the current difference line current scalar value The current scalar value is subtracted. In the third embodiment, instead of subtracting after the scalar value calculation as shown in FIG. 6, the phase difference θ of the phase current at the present time and a predetermined time before is obtained in each phase, and the phase current a predetermined time before the current phase current is obtained. Is subtracted from the value corrected by the phase difference θ.
ステップS31では、各相において相電流を系統周波数のN周期分(Nは整数)の値を保持する。
ステップS32では、各相において現時点の相電流と(N−1)個前の相電流の位相差θを計測した後、(N−1)個前の相電流を位相差θだけ補正して現時点の相電流の位相における相電流の差分をそれぞれ算出する。
In step S31, the phase current for each phase is held for N periods of the system frequency (N is an integer).
In step S32, the phase difference θ between the current phase current and (N−1) previous phase currents in each phase is measured, and then the (N−1) previous phase currents are corrected by the phase difference θ. The difference of the phase current in the phase of each phase current is calculated.
ステップS33では、各相の差分相電流に基づいて各相間の差分線間電流をそれぞれ算出し、ステップS34では、各相間の差分線間電流からそれぞれのスカラー値を算出する。この実施の形態2では、ステップS22において現時点とそれ以前の相電流の差分を補正したため、実施の形態1及び実施の形態2におけるステップS15、S25に相当する処理は行わない。
ステップS35以降は、実施の形態1におけるステップS16以降と同様のため、説明を省略する。
In step S33, the difference line current between each phase is calculated based on the difference phase current of each phase, and in step S34, each scalar value is calculated from the difference line current between each phase. In the second embodiment, since the difference between the current phase and the previous phase current is corrected in step S22, the processing corresponding to steps S15 and S25 in the first and second embodiments is not performed.
Since step S35 and subsequent steps are the same as step S16 and subsequent steps in the first embodiment, description thereof is omitted.
この実施の形態によれば、各相において検出タイミングの異なる相電流の位相差θを求め、この位相差θ分だけ補正して同一位相とした2つの相電流の差分を算出し、この相電流の差分に基づいて各相間の差分線間電流のスカラー値を求め、スカラー値のうち1つだけが所定値未満のとき1線地絡事故としての事故相を判定することにより、入力電流の系統周波数が変動しても負荷電流の誤差を相殺して1線地絡事故の事故相を正確に選別できる。さらに、事故継続中は正常時との位相差θを補正することにより、緩やかな周波数変動による負荷電流の誤差も軽減できる。 According to this embodiment, the phase difference θ of phase currents having different detection timings in each phase is obtained, and the difference between two phase currents that are corrected by the phase difference θ and set to the same phase is calculated. By calculating the scalar value of the differential line current between each phase based on the difference between the phases and determining the fault phase as a one-line ground fault when only one of the scalar values is less than the predetermined value, the input current system Even if the frequency fluctuates, the error of the load current can be offset and the accident phase of the one-wire ground fault can be accurately selected. Further, by correcting the phase difference θ from the normal state while the accident continues, the load current error due to the gradual frequency fluctuation can be reduced.
また、各相間のスカラー値が全て所定値よりも大きいか判定することにより、1線地絡事故だけでなく2線事故または3線事故の事故相選別もできる。 Further, by determining whether the scalar values between the phases are all greater than a predetermined value, it is possible to select not only the 1-line ground fault but also the 2-line or 3-line accident phase.
また、1線地絡事故の場合に差分相電流を用いることで事故相を容易に特定できる。 Moreover, the accident phase can be easily specified by using the differential phase current in the case of a one-wire ground fault.
また、2線事故及び3線事故については実施の形態1と同様の効果を得る。 Further, the effects similar to those of the first embodiment are obtained for the 2-wire accident and the 3-wire accident.
1 事故相選別装置
2 距離リレー
3 CPU
4 AI回路
5 A/D変換回路
6 出力回路
7 送電線
8 遮断器
9 CT(Current Transformer)
10 PT (Potential Transformer)
11 信号線
101 入力データ保持部
102 事故相選別部
31 距離要素演算部
32 ロジック演算部
1 Accident
4 AI circuit 5 A / D conversion circuit 6 Output circuit 7 Transmission line 8 Circuit breaker 9 CT (Current Transformer)
10 PT (Potential Transformer)
11 Signal line 101 Input data holding unit 102 Accident phase selection unit 31 Distance
Claims (9)
検出タイミングの異なる相電流の差分を各相毎に算出する差分相電流算出手段と、前記差分相電流算出手段で得られた各相の差分相電流に基づいて差分線間電流をそれぞれ算出する差分線間電流演算手段と、前記差分線間電流演算手段で得られた各相間の差分線間電流のスカラー値をそれぞれ算出するスカラー値算出手段と、現時点における差分線間電流のスカラー値からそれ以前における差分線間電流のスカラー値を各相間毎に減算する差分スカラー値演算手段と、前記差分スカラー値演算手段で得られた各相間の差分スカラー値のうち1つだけが所定値未満のときに1線地絡事故としての事故相を判定する判定手段とを備えたことを特徴とする事故相選別装置。 In the accident phase sorting device that sorts out the accident phase at the time of transmission line accident based on the current value flowing through the transmission line,
Difference phase current calculation means for calculating the difference between phase currents having different detection timings for each phase, and difference for calculating the difference line current based on the difference phase current of each phase obtained by the difference phase current calculation means. Line value current calculation means, scalar value calculation means for calculating the scalar value of the difference line current between the phases obtained by the difference line current calculation means, respectively, and the current value of the difference line current current value before that When the difference scalar value calculating means for subtracting the scalar value of the difference line current for each phase between each phase and the difference scalar value between the phases obtained by the difference scalar value calculating means is less than a predetermined value An accident phase selection device comprising: a determination unit that determines an accident phase as a one-line ground fault.
検出タイミングの異なる相電流の位相差を補正して同一位相における差分を各相毎に算出する差分相電流算出手段と、前記差分相電流算出手段で得られた各相の差分相電流に基づいて差分線間電流をそれぞれ算出する差分線間電流演算手段と、前記差分線間電流演算手段で得られた各相間の差分線間電流のスカラー値をそれぞれ算出するスカラー値算出手段と、前記スカラー値算出手段で得られた各相間の差分線間電流のスカラー値のうち1つだけが所定値未満のときに1線地絡事故としての事故相を判定する判定手段とを備えたことを特徴とする事故相選別装置。 In the accident phase sorting device that sorts out the accident phase at the time of transmission line accident based on the current value flowing through the transmission line,
Based on the differential phase current calculation means for correcting the phase difference between the phase currents with different detection timings and calculating the difference in the same phase for each phase, and the differential phase current of each phase obtained by the differential phase current calculation means Difference line current calculation means for calculating a difference line current, scalar value calculation means for calculating a scalar value of a difference line current between phases obtained by the difference line current calculation means, and the scalar value And determining means for determining an accident phase as a one-line ground fault when only one of the scalar values of the difference line current between the phases obtained by the calculating means is less than a predetermined value. Accident phase sorting device.
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