JP3763345B2

JP3763345B2 - Ratio differential relay

Info

Publication number: JP3763345B2
Application number: JP2000258295A
Authority: JP
Inventors: 孝志川本; 裕一安居; 修司山崎
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2000-08-29
Filing date: 2000-08-29
Publication date: 2006-04-05
Anticipated expiration: 2020-08-29
Also published as: JP2002078186A

Description

【０００１】
【発明の属する技術分野】
本発明は、電力系統の保護区間の差電流に基づき内部事故を判定する差動継電装置に係わり、特に通過電流に比例して動作設定値が大きくなる比率差動継電装置に関する。
【０００２】
【従来の技術】
一般に、差動継電装置は、保護区間に流入する電流と保護区間から流出する電流との差電流を判別して内部事故か否かの判定を行う。すなわち、内部事故のないときは電流の流入と流出は等しく差電流は零であり、内部事故があると故障電流が流れることから差電流が故障電流として表れる。この差電流が動作設定値を超えたときに内部事故と判定し動作する。
【０００３】
また、保護区間の通過電流が大になると、両端の電圧を検出する電流変成器の誤差により保護区間外部故障で誤動作の可能性があるので、動作設定値が通過電流の増加に伴って大きくなる比率差動継電器が用いられている。
【０００４】
図４は比率差動継電装置を長距離線路の電力系統に適用した保護継電システムの全体構成図である。電力系統の保護区間の両端Ａ、Ｂには、それぞれ比率差動継電装置１Ａ、１Ｂが設置されている。いま、電力系統のＡ端子を自端子とし、Ｂ端子を他端子とする。
【０００５】
比率差動継電装置１Ａには計器用変成器２Ａおよび限流変流器３Ａを介してＡ端子の電流Ｉａが入力される。このＡ端子の電流Ｉａは、絶縁変流器４Ａ１、Ａ通信線路５Ａ、絶縁変流器４Ａ２を介して相手端であるＢ端子の比率差動継電装置１Ｂに入力される。相手端の比率差動継電装置１Ｂにおいては計器用変成器２Ｂおよび限流変流器３Ｂを介してＢ端子の電流Ｉｂが入力され、Ａ端子から送られてきた電流Ｉａとの差電流が演算される。
【０００６】
同様に、比率差動継電装置１Ａには、相手端であるＢ端子の電流Ｉｂが絶縁変流器４Ｂ１、Ｂ通信線路５、絶縁変流器４Ｂ２を介して入力され、自端の電流Ｉａとの差電流が演算される。そして、比率差動継電装置１Ａ、１Ｂのいずれかが動作すると、保護区間の遮断器６Ａ、６Ｂを開放する。
【０００７】
図５は、比率差動継電装置１のブロック構成図である。自端と相手端の電流Ｉａ、Ｉｂは、比率差動継電装置１の入力変換器７に入力され、Ａ／Ｄ変換器８アナログ量からディジタル量に変換され、リレー判定演算部９に入力される。リレー判定演算部９では自端電流Ｉａと相手端電流Ｉｂとの差電流を演算し、その差電流が動作設定値を超えたか否かを判定し、動作設定値を超えたときはシーケンス処理部１０を介して出力処理部１１から遮断器６Ａ、６Ｂにトリッブ信号を出力し、保護区間の長距離線路の保護を行う。
【０００８】
【発明が解決しようとする課題】
ところが、比率差動継電装置を長距離線路に適用した場合には、相手端の電流を取り込むための通信線路５Ａ、５Ｂが長くなるので、通信線路５Ａ、５Ｂの線路インダクタンスにより受信側波形に減衰と位相遅れが発生する。相手端の電流に減衰および位相遅れが発生すると、精度良い差動演算を行うことができなくなる。
【０００９】
従来の比率差動継電装置１では、相手端の電流の減衰率と位相遅れとを検出する処理が実装されていないため、リレー判定演算部９のリレー演算処理に誤差が生じ、精度の良い演算結果が得られず、誤動作および誤不動作の可能性がある。
【００１０】
本発明の目的は、相手端の電流の減衰率および位相遅れを検出でき、精度良くリレー判定演算を行うことができる比率差動継電装置を提供することである。
【００１１】
【課題を解決するための手段】
請求項１の発明に係わる比率差動継電装置は、電力系統の保護区間の両端に設けられ、自端の電流は計器用変流器を介して入力し相手端の電流は通信線路を介して入力し、自端の電流と相手端の電流との差電流が前記保護区間の通過電流に比例して大きくなる動作設定値を超えたとき動作する比率差動継電装置において、自端の電流および相手端の電流を所定の周期でサンプリングしてディジタル量に変換するＡ／Ｄ変換器と、前記Ａ／Ｄ変換器で得られた自端の電流と相手端の電流との差電流が動作設定値を超えたか否かの判定演算を行い差電流が動作設定値を超えたときに動作するリレー判定演算部と、前記リレー判定演算部が動作したとき保護区間の両端の遮断器にトリップ信号を出力する出力処理部と、前記通信線路による相手端の電流の減衰および位相遅れを補償するための定数を算出し前記リレー判定演算部の判定演算に補正を加える演算補正部とを備え、
演算補正部は、前記通信線路の減衰量および位相遅れを求める検出処理部と、前記検出処理部で求めた減衰量に基づいて減衰定数を算出すると共に前記位相遅れに基づいて位相定数を算出する定数算出部と、前記定数算出部で算出された減衰定数および位相定数を前記リレー判定演算部に出力する補正出力部とを備え、
前記検出処理部は、両端の比例差動継電装置を電力系統から切り離した状態で２つの前記通信線路に試験電流を流し、２つの前記通信線路の減衰量差、位相遅れ差、減衰量和および位相遅れ和を求め、これら２つの前記通信線路の減衰量差、位相遅れ差、減衰量和および位相遅れ和に基づいて前記通信線路の減衰定数および位相定数を求めることを特徴とする。
【００１２】
請求項１の発明に係わる比率差動継電装置においては、演算補正部は、通信線路による相手端の電流の減衰および位相遅れを補償するための定数を算出しリレー判定演算部の判定演算に補正を加える。リレー判定演算部は、演算補正部からの定数に基づいてＡ／Ｄ変換器で得られた相手端の電流の減衰および位相遅れを補償し、その補償した相手端の電流およびＡ／Ｄ変換器で得られた自端の電流の差電流に基づいてリレー判定演算を行う。そして、差電流が動作設定値を超えたときに、出力処理部から保護区間の両端の遮断器にトリップ信号が出力される。
【００１４】
また、演算補正部の検出処理部では、通信線路の減衰量および位相遅れを検出し、定数算出部で、検出処理部で検出した減衰量に基づいて減衰定数を算出すると共に位相遅れに基づいて位相定数を算出する。そして、補正出力部から算出された減衰定数および位相定数をリレー判定演算部に出力する。
【００１５】
請求項２の発明に係わる比率差動継電装置は、請求項１の発明において、リレー判定演算部は、相手端の電流として、通信線路から入力した相手端の電流に演算補正部からの減衰定数で除算すると共に、演算補正部からの位相定数に相当するサンプリング周期分だけ過去の電流データを使用してリレー判定演算を行うことを特徴とする。
【００１６】
請求項２の発明に係わる比率差動継電装置においては、請求項１の発明の作用に加え、通信線路から入力した相手端の電流に演算補正部からの減衰定数で除算する。これにより、減衰による補正を行う。また、演算補正部からの位相定数に相当するサンプリング周期分だけ過去の電流データを使用する。これにより、位相遅れ分を補正する。
【００１７】
【発明の実施の形態】
以下、本発明の実施の形態を説明する。図１は本発明の実施の形態に係わる比率差動継電装置のブロック構成図である。この実施の形態は、図４に示した従来例に対し、通信線路５による相手端の電流の減衰および位相遅れを補償するための定数を算出しリレー判定演算部９の判定演算に補正を加える演算補正部１２を追加して設けたものである。その他の構成は、図４に示した従来例と同一であるので、同一要素には同一符号を付し重複する説明は省略する。
【００１８】
演算補正部１２は、通信線路５Ａ、５Ｂによる相手端の電流の減衰および位相遅れを補償するための定数を算出し、リレー判定演算部９の判定演算に補正を加えるものである。この演算補正部１２は、後述するように比率差動継電装置１Ａ、１Ｂを電力系統から切り離した状態で試験電流Ｉを流し、通信線路５Ａ、５Ｂの減衰量および位相遅れを求め、さらに減衰定数および位相定数を算出する。
【００１９】
すなわち、演算補正部１２の検出処理部１３は、試験電流Ｉが流れている状態で通信線路５Ａ、５Ｂの減衰量および位相遅れを検出する。この場合、減衰量および位相遅れの計測中であることは計測中表示部１４に表示される。
【００２０】
定数算出部１５は、検出処理部１３で検出された減衰量に基づいて減衰定数を算出する。また、検出処理部１３で検出された位相遅れに基づいて位相定数を算出する。定数算出部１５で算出された減衰定数および位相定数は、定数表示部１６に表示されると共に記憶部１７に記憶される。そして、補正出力部１８は定数算出部１５で算出され記憶部１７に記憶された減衰定数および位相定数をリレー判定演算部９に出力し、補正を加えるようになっている。
【００２１】
次に、検出処理部１３での減衰定数および位相定数を求め方を説明する。検出処理部１３では、通信線路５Ａの減衰量と通信線路５Ｂの減衰量との減衰量差ΔＩ、および通信線路５Ａの位相遅れと通信線路５Ｂの位相遅れとの位相遅れ差Δθを求め、さらに、通信線路５Ａの減衰量と通信線路５Ｂの減衰量との減衰量和ΣＩ、および通信線路５Ａの位相遅れと通信線路５Ｂの位相遅れとの位相遅れ和Σθを求め、減衰量差ΔＩ、減衰量和ΣＩ、位相遅れ差Δθ、位相遅れ和Σθに基づいて減衰定数および位相定数を求める。
【００２２】
図２は、検出処理部１３において、通信線路５Ａの減衰量と通信線路５Ｂの減衰量との減衰量差ΔＩ、および通信線路５Ａの位相遅れと通信線路５Ｂの位相遅れとの位相遅れ差Δθを求める場合の試験回路構成を示している。なお、図２では自端の比率差動継電装置１Ａの内部構成の図示を一部省略している。
【００２３】
まず、自端の比率差動継電装置１Ａおよび相手端の比率差動継電装置１Ｂを電力系統から切り離す。すなわち、限流変流器３Ａ、３Ｂからの入力を遮断し、相手端側に試験電源１９を接続し、この試験電源１９から通信線路５Ａ、５Ｂに同一の試験電流Ｉを流す。
【００２４】
いま、Ａ通信線路５Ａの減衰率をαａ、位相遅れをθａとし、また、Ｂ通信線路５Ｂの減衰率をαｂ、位相遅れをθｂとする。さらに自端の比率差動継電装置１Ａに入力されるＡ通信線路５Ａからの電流をＩａ、Ｂ通信線路５Ｂからの電流をＩｂ、電流Ｉａと電流Ｉｂとの位相差をΔθとする。
【００２５】
この場合、Ａ通信線路５Ａからの電流ＩａおよびＢ通信線路５Ｂからの電流Ｉｂは、下記（１）式および（２）式で示される。
【００２６】
Ｉａ＝（１−αａ）Ｉ …（１）
Ｉｂ＝（１−αｂ）Ｉ …（２）
【００２７】
また、通信線路５Ａの減衰量αａＩと通信線路５Ｂの減衰量αｂＩとの減衰量差ΔＩは、下記（３）式で求められる。
【００２８】

【００２９】
一方、通信線路５Ａの位相遅れθａと通信線路５Ｂの位相遅れθｂとの位相遅れ差Δθは（４）式で示され、電流Ｉａと電流Ｉｂとの位相差として求められる。従って、下記（５）式により、通信線路５Ａの位相遅れθａと通信線路５Ｂの位相遅れθｂとの位相遅れ差Δθが求められる。
【００３０】
Δθ＝θｂ−θａ …（４）
Δθ＝ＣＯＳ^-1（Ｉａ・Ｉｂ／｜Ｉａ｜｜Ｉｂ｜） …（５）
【００３１】
図３は、検出処理部１３において、通信線路５Ａの減衰量と通信線路５Ｂの減衰量との減衰量和ΣＩ、および通信線路５Ａの位相遅れと通信線路５Ｂの位相遅れとの位相遅れ和Σθを求める場合の試験回路構成を示している。なお、図３では自端の比率差動継電装置１Ａの内部構成の図示を一部省略している。
【００３２】
まず、自端の比率差動継電装置１Ａおよび相手端の比率差動継電装置１Ｂを電力系統から切り離す。すなわち、限流変流器３Ａ、３Ｂからの入力を遮断し、自端側に試験電源１９を接続し、この試験電源１９から通信線路５Ａおよび通信線路５Ｂを経由する試験電流Ｉを流す。
【００３３】
いま、Ａ通信線路５Ａの減衰率をαａ、位相遅れをθａとし、また、Ｂ通信線路５Ｂの減衰率をαｂ、位相遅れをθｂとする。さらに自端の比率差動継電装置１Ａに入力される電流をＩａ’、Ｂ通信線路５Ｂからの電流をＩｂ’、電流Ｉａ’と電流Ｉｂ’との位相差をΣθとする。
【００３４】
この場合、Ａ通信線路５Ａに流れる電流Ｉａ’は試験電流Ｉそのものとなり、Ｂ通信線路５Ｂからの電流Ｉｂ’は、通信線路５Ａおよび通信線路５Ｂを経由してきた電流となり、下記（６）式および（７）式でそれぞれ示される。
【００３５】
Ｉａ’＝Ｉ …（６）
Ｉｂ’＝（１−αａ−αｂ）Ｉ …（７）
【００３６】
また、通信線路５Ａの減衰量αａＩと通信線路５Ｂの減衰量αｂＩとの減衰量和ΣΔＩは、下記（８）式で求められる。
【００３７】

【００３８】
一方、通信線路５Ａの位相遅れθａと通信線路５Ｂの位相遅れθｂとの位相遅れ和Σθは（９）式で示され、電流Ｉａと電流Ｉｂとの位相差として求められる。従って、下記（１０）式により、通信線路５Ａの位相遅れθａと通信線路５Ｂの位相遅れθｂとの位相遅れ和Σθが求められる。
【００３９】
Σθ＝θａ＋θｂ …（９）
Σθ＝ＣＯＳ^-1（Ｉａ’・Ｉｂ’／｜Ｉａ’｜｜Ｉｂ’｜） …（１０）
【００４０】
従って、Ａ通信線路５Ａの減衰量αａＩおよびＢ通信線路５Ｂの減衰量αｂＩは、（３）式で求めた減衰量差ΔＩと（８）式で求めた減衰量和ΣＩとから、下記（１１）式および（１２）式により求められる。
【００４１】
αａＩ＝（ΣＩ−ΔＩ）／２ …（１１）
αｂＩ＝（ΣＩ＋ΔＩ）／２ …（１２）
【００４２】
同様に、Ａ通信線路５Ａの位相遅れθａおよびＢ通信線路５Ｂの位相遅れθｂは、（４）式および（９）式より、下記（１３）式および（１４）式で求められる。
【００４３】
θａ＝（Σθ−Δθ）／２ …（１３）
θｂ＝（Σθ＋Δθ）／２ …（１４）
【００４４】
このようにして求めた通信線路５Ａ、５Ｂの減衰量αａＩ、αｂＩ、位相遅れθａ、θｂは、定数算出部１５に入力され、定数算出部１５において、減衰定数および位相定数を算出する。すなわち、Ａ通信線路５Ａの減衰定数βａおよびＢ通信線路５Ｂの減衰定数βｂは、（１５）式および（１６）式のように求められる。
【００４５】
βａ＝１−αａＩ／Ｉ＝１−αａ …（１５）
βｂ＝１−αｂＩ／Ｉ＝１−αｂ …（１６）
【００４６】
また、Ａ通信線路５Ａの位相定数τａおよびＢ通信線路５Ｂの位相定数τｂは、（１７）式および（１８）式のように求められる。ここで、Ｋは位相遅れθａ、θｂを何回のサンプリング周期分に相当するかに変換するための定数である。
【００４７】
τａ＝Ｋθａ …（１７）
τｂ＝Ｋθｂ …（１８）
【００４８】
すなわち、位相定数τａ、τｂは、位相遅れθａ、θｂを補償するために何回前のサンプリング周期の電流データを用いればよいかを示す定数である。
【００４９】
定数算出部１５で求められた減衰定数βａ、βｂおよび位相定数τａ、τｂは定数表示部１６に表示されると共に記憶部１７に記憶される。そして、記憶部１７に記憶された減衰定数βａ、βｂおよび位相定数τａ、τｂは、補正出力部１８からリレー判定演算部９に出力され、リレー判定演算部９において、通信線路５Ａ、５Ｂから入力した相手端の電流に演算補正部１２からの減衰定数βａ、βｂで除算すると共に、位相定数τａ、τｂに相当するサンプリング周期分だけ過去の電流データを使用してリレー判定演算を行う。これにより、減衰および位相遅れを補償する。
【００５０】
【発明の効果】
以上、説明したように、本発明によれば、減衰量および位相遅れを計測し相手端の入力電流の減衰定数および位相定数を算出し、これらを補償するので比率差動継電装置の整定時に誤動作および誤不動作を防止できる整定値を設定できる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係わる比率差動継電装置のブロック構成図。
【図２】本発明の実施の形態における検出処理部において、２つの通信線路の減衰量差ΔＩ、および位相遅れ差Δθを求める場合の試験回路の構成図。
【図３】本発明の実施の形態における検出処理部において、２つの通信線路の減衰量和ΣＩ、および位相遅れ和Σθを求める場合の試験回路の構成図。
【図４】従来の比率差動継電装置を長距離線路の電力系統に適用した保護継電システムの全体構成図。
【図５】従来の比率差動継電装置１のブロック構成図。
【符号の説明】
１…比率差動継電装置、２…計器用変成器、３…限流変流器、４…絶縁変流器、５…通信線路、６…遮断器、７…入力変換部、８…Ａ／Ｄ変換器、９…比率電流差動継電器、１０…シーケンス処理部、１１…出力処理部、１２…演算補正部、１３…検出処理部、１４…計測中表示部、１５…定数算出部、１６…定数表示部、１７…記憶部、１８…補正出力部、１９…試験電源[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a differential relay device that determines an internal fault based on a difference current in a protection section of a power system, and more particularly to a ratio differential relay device in which an operation set value increases in proportion to a passing current.
[0002]
[Prior art]
Generally, the differential relay device determines whether or not there is an internal accident by determining a difference current between a current flowing into the protection section and a current flowing out from the protection section. That is, when there is no internal fault, the inflow and outflow of current are equal and the difference current is zero. When there is an internal fault, the fault current flows, so the difference current appears as a fault current. When this difference current exceeds the operation set value, it is determined that there is an internal accident and the operation is performed.
[0003]
Also, if the passing current in the protection zone becomes large, there is a possibility of malfunction due to an external failure in the protection zone due to the error of the current transformer that detects the voltage at both ends, so the operation set value increases as the passing current increases Ratio differential relays are used.
[0004]
FIG. 4 is an overall configuration diagram of a protective relay system in which the ratio differential relay device is applied to a long-distance power system. Ratio

differential relay devices

1A and 1B are respectively installed at both ends A and B of the protection section of the power system. Now, let the A terminal of the power system be its own terminal and the B terminal be the other terminal.
[0005]
The current Ia at the A terminal is input to the ratio differential relay device 1A via the instrument transformer 2A and the current limiting current transformer 3A. The current Ia at the A terminal is input to the ratio differential relay device 1B at the B terminal, which is the counterpart, via the insulation current transformer 4A1, the A communication line 5A, and the insulation current transformer 4A2. In the counter differential relay device 1B at the other end, the current Ib at the B terminal is input via the instrument transformer 2B and the current limiting current transformer 3B, and the difference current from the current Ia sent from the A terminal is Calculated.
[0006]
Similarly, the current Ib at the B terminal, which is the other end, is input to the ratio differential relay device 1A via the insulation current transformer 4B1, the B communication line 5, and the insulation current transformer 4B2, and the current Ia at its own end is input. Is calculated. And when either of ratio

differential relay devices

1A and 1B operate | moves, the

circuit breakers

6A and 6B of a protection area will be open | released.
[0007]
FIG. 5 is a block configuration diagram of the ratio differential relay device 1. The currents Ia and Ib of the local end and the counterpart end are input to the input converter 7 of the ratio differential relay device 1, converted from an analog amount to a digital amount by the A / D converter 8, and input to the relay determination calculation unit 9. Is done. The relay determination calculation unit 9 calculates a difference current between the local end current Ia and the counterpart end current Ib, determines whether or not the difference current exceeds the operation set value, and when the operation set value is exceeded, the sequence processing unit A trip signal is output from the output processing unit 11 to the

circuit breakers

6A and 6B via 10 to protect the long-distance line in the protection section.
[0008]
[Problems to be solved by the invention]
However, when the ratio differential relay device is applied to a long-distance line, the

communication lines

5A and 5B for taking in the current at the other end become longer, so that the receiving side waveform is caused by the line inductance of the

communication lines

5A and 5B. Attenuation and phase lag occur. If attenuation and phase delay occur in the current at the other end, accurate differential calculation cannot be performed.
[0009]
In the conventional ratio differential relay device 1, since the process for detecting the attenuation rate and phase delay of the current at the other end is not implemented, an error occurs in the relay calculation process of the relay determination calculation unit 9, and the accuracy is high. An operation result cannot be obtained, and there is a possibility of malfunction and malfunction.
[0010]
An object of the present invention is to provide a ratio differential relay device that can detect the attenuation rate and phase delay of the current at the other end and perform relay determination calculation with high accuracy.
[0011]
[Means for Solving the Problems]
The ratio differential relay device according to the invention of claim 1 is provided at both ends of the protection section of the electric power system, the current at its own end is input via a current transformer for the instrument, and the current at the other end is transmitted via a communication line. In the differential relay device that operates when the difference current between the current at the local end and the current at the other end exceeds an operation set value that increases in proportion to the passing current of the protection section, An A / D converter that samples the current and the current at the other end into a digital quantity by sampling at a predetermined cycle, and a difference current between the current at the end and the current at the other end obtained by the A / D converter is The relay judgment calculation unit that operates when the differential current exceeds the operation set value by performing the calculation of whether or not the operation set value has been exceeded, and trips to the circuit breakers at both ends of the protection section when the relay determination calculation unit operates. An output processing unit that outputs a signal, and the other end of the communication line And an arithmetic correction unit calculates the constants to compensate for the attenuation and phase lag of the flow correction is applied to the determination operation of the relay determination computing unit,
The calculation correction unit calculates the attenuation constant and the phase delay of the communication line, calculates the attenuation constant based on the attenuation obtained by the detection processing unit, and calculates the phase constant based on the phase delay A constant calculation unit, and a correction output unit that outputs the attenuation constant and the phase constant calculated by the constant calculation unit to the relay determination calculation unit,
The detection processing unit causes a test current to flow through the two communication lines in a state in which the proportional differential relay devices at both ends are disconnected from the power system, and the attenuation difference, phase delay difference, and attenuation sum of the two communication lines. The phase delay sum is obtained, and the attenuation constant and phase constant of the communication line are obtained on the basis of the attenuation difference, phase delay difference, attenuation sum, and phase delay sum of the two communication lines .
[0012]
In the ratio differential relay device according to the first aspect of the present invention, the calculation correction unit calculates a constant for compensating for the attenuation and phase delay of the current at the other end by the communication line, and performs the determination calculation of the relay determination calculation unit. Add corrections. The relay determination calculation unit compensates for the attenuation and phase lag of the counterpart current obtained by the A / D converter based on the constant from the calculation correction unit, and the compensated counterpart current and A / D converter The relay determination calculation is performed on the basis of the difference current between the currents obtained at step 1. When the difference current exceeds the operation set value, a trip signal is output from the output processing unit to the circuit breakers at both ends of the protection section.
[0014]
In addition , the detection processing unit of the calculation correction unit detects the attenuation amount and phase delay of the communication line, and the constant calculation unit calculates the attenuation constant based on the attenuation detected by the detection processing unit and based on the phase delay. Calculate the phase constant. Then, the attenuation constant and the phase constant calculated from the correction output unit are output to the relay determination calculation unit.
[0015]
The ratio differential relay device according to the invention of claim 2 is the ratio differential relay device according to claim 1 , wherein the relay determination calculation unit attenuates the current of the other end input from the communication line as the current of the other end from the calculation correction unit. In addition to dividing by a constant, relay determination calculation is performed using past current data for a sampling period corresponding to the phase constant from the calculation correction unit.
[0016]
In the ratio differential relay device according to the invention of claim 2 , in addition to the operation of the invention of claim 1 , the current at the other end inputted from the communication line is divided by the attenuation constant from the calculation correction unit. Thereby, correction by attenuation is performed. Further, past current data is used for the sampling period corresponding to the phase constant from the calculation correction unit. As a result, the phase delay is corrected.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is a block diagram of a differential relay device according to an embodiment of the present invention. In this embodiment, a constant for compensating for the attenuation and phase delay of the current at the other end of the communication line 5 is calculated with respect to the conventional example shown in FIG. An arithmetic correction unit 12 is additionally provided. Since the other configuration is the same as that of the conventional example shown in FIG. 4, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0018]
The calculation correction unit 12 calculates a constant for compensating for the attenuation and phase delay of the current at the other end by the

communication lines

5A and 5B, and corrects the determination calculation of the relay determination calculation unit 9. As will be described later, the calculation correction unit 12 causes the test current I to flow in a state where the ratio

differential relay devices

1A and 1B are disconnected from the power system, obtains attenuation amounts and phase delays of the

communication lines

5A and 5B, and further attenuates Calculate constants and phase constants.
[0019]
That is, the detection processing unit 13 of the calculation correction unit 12 detects the attenuation amount and the phase delay of the

communication lines

5A and 5B in a state where the test current I is flowing. In this case, the fact that the attenuation amount and the phase delay are being measured is displayed on the display unit 14 during measurement.
[0020]
The constant calculation unit 15 calculates an attenuation constant based on the attenuation amount detected by the detection processing unit 13. Further, the phase constant is calculated based on the phase delay detected by the detection processing unit 13. The attenuation constant and the phase constant calculated by the constant calculation unit 15 are displayed on the constant display unit 16 and stored in the storage unit 17. Then, the correction output unit 18 outputs the attenuation constant and the phase constant calculated by the constant calculation unit 15 and stored in the storage unit 17 to the relay determination calculation unit 9 to be corrected.
[0021]
Next, how to obtain the attenuation constant and phase constant in the detection processing unit 13 will be described. The detection processing unit 13 obtains the attenuation difference ΔI between the attenuation amount of the communication line 5A and the attenuation amount of the communication line 5B, and the phase delay difference Δθ between the phase delay of the communication line 5A and the phase delay of the communication line 5B. Then, the attenuation amount sum ΣI of the attenuation amount of the communication line 5A and the attenuation amount of the communication line 5B, and the sum of phase delays Σθ of the phase delay of the communication line 5A and the phase delay of the communication line 5B are obtained. An attenuation constant and a phase constant are obtained based on the quantity sum ΣI, the phase delay difference Δθ, and the phase delay sum Σθ.
[0022]
2 shows the detection processing unit 13 in which the difference ΔI between the attenuation amount of the communication line 5A and the attenuation amount of the communication line 5B and the phase delay difference Δθ between the phase delay of the communication line 5A and the phase delay of the communication line 5B are detected. 2 shows a test circuit configuration in the case of obtaining. In FIG. 2, a part of the internal configuration of the self-proportional ratio differential relay device 1A is partially omitted.
[0023]
First, the own ratio differential relay device 1A and the counterpart ratio differential relay device 1B are disconnected from the power system. That is, the input from the current limiting

current transformers

3A and 3B is cut off, the test power supply 19 is connected to the other end, and the same test current I is supplied from the test power supply 19 to the

communication lines

5A and 5B.
[0024]
Now, the attenuation rate of the A communication line 5A is αa, the phase delay is θa, the attenuation rate of the B communication line 5B is αb, and the phase delay is θb. Further, let Ia be the current from the A communication line 5A input to the self-proportional differential relay device 1A, Ib be the current from the B communication line 5B, and Δθ be the phase difference between the current Ia and the current Ib.
[0025]
In this case, the current Ia from the A communication line 5A and the current Ib from the B communication line 5B are expressed by the following expressions (1) and (2).
[0026]
Ia = (1-αa) I (1)
Ib = (1−αb) I (2)
[0027]
Further, the attenuation difference ΔI between the attenuation amount αaI of the communication line 5A and the attenuation amount αbI of the communication line 5B can be obtained by the following equation (3).
[0028]

[0029]
On the other hand, the phase delay difference Δθ between the phase delay θa of the communication line 5A and the phase delay θb of the communication line 5B is expressed by the equation (4), and is obtained as the phase difference between the current Ia and the current Ib. Therefore, the phase delay difference Δθ between the phase delay θa of the communication line 5A and the phase delay θb of the communication line 5B is obtained by the following equation (5).
[0030]
Δθ = θb−θa (4)
Δθ = COS ⁻¹ (Ia · Ib / | Ia || Ib |) (5)
[0031]
FIG. 3 illustrates the detection processing unit 13 in which the attenuation amount ΣI of the attenuation amount of the communication line 5A and the attenuation amount of the communication line 5B, and the phase delay sum Σθ of the phase delay of the communication line 5A and the phase delay of the communication line 5B. 2 shows a test circuit configuration in the case of obtaining. In FIG. 3, the internal configuration of the self-proportional ratio differential relay device 1 </ b> A is partially omitted.
[0032]
First, the own ratio differential relay device 1A and the counterpart ratio differential relay device 1B are disconnected from the power system. That is, the input from the current limiting

current transformers

3A and 3B is cut off, the test power supply 19 is connected to the self-end side, and the test current I is passed from the test power supply 19 via the communication line 5A and the communication line 5B.
[0033]
Now, the attenuation rate of the A communication line 5A is αa, the phase delay is θa, the attenuation rate of the B communication line 5B is αb, and the phase delay is θb. Further, let Ia ′ be the current input to the self-end ratio differential relay device 1A, Ib ′ be the current from the B communication line 5B, and Σθ be the phase difference between the current Ia ′ and the current Ib ′.
[0034]
In this case, the current Ia ′ flowing through the A communication line 5A is the test current I itself, and the current Ib ′ from the B communication line 5B is the current that has passed through the communication line 5A and the communication line 5B. It is shown by the equation (7).
[0035]
Ia ′ = I (6)
Ib ′ = (1−αa−αb) I (7)
[0036]
Further, the attenuation sum ΣΔI of the attenuation amount αaI of the communication line 5A and the attenuation amount αbI of the communication line 5B can be obtained by the following equation (8).
[0037]

[0038]
On the other hand, the phase delay sum Σθ of the phase delay θa of the communication line 5A and the phase delay θb of the communication line 5B is expressed by the equation (9), and is obtained as a phase difference between the current Ia and the current Ib. Therefore, the phase delay sum Σθ of the phase delay θa of the communication line 5A and the phase delay θb of the communication line 5B is obtained by the following equation (10).
[0039]
Σθ = θa + θb (9)
Σθ = COS ⁻¹ (Ia ′ · Ib ′ / | Ia ′ || Ib ′ |) (10)
[0040]
Therefore, the attenuation amount αaI of the A communication line 5A and the attenuation amount αbI of the B communication line 5B are expressed by the following (11) from the attenuation amount difference ΔI obtained by the equation (3) and the attenuation amount sum ΣI obtained by the equation (8). ) And (12).
[0041]
αaI = (ΣI−ΔI) / 2 (11)
αbI = (ΣI + ΔI) / 2 (12)
[0042]
Similarly, the phase delay θa of the A communication line 5A and the phase delay θb of the B communication line 5B are obtained by the following expressions (13) and (14) from the expressions (4) and (9).
[0043]
θa = (Σθ−Δθ) / 2 (13)
θb = (Σθ + Δθ) / 2 (14)
[0044]
The attenuation amounts αaI and αbI and the phase delays θa and θb of the

communication lines

5A and 5B thus obtained are input to the constant calculation unit 15, and the constant calculation unit 15 calculates the attenuation constant and the phase constant. That is, the attenuation constant βa of the A communication line 5A and the attenuation constant βb of the B communication line 5B are obtained as in Expressions (15) and (16).
[0045]
βa = 1−αaI / I = 1−αa (15)
βb = 1−αbI / I = 1−αb (16)
[0046]
Further, the phase constant τa of the A communication line 5A and the phase constant τb of the B communication line 5B are obtained as in Expressions (17) and (18). Here, K is a constant for converting the number of sampling periods corresponding to the phase delays θa and θb.
[0047]
τa = Kθa (17)
τb = Kθb (18)
[0048]
That is, the phase constants τa and τb are constants that indicate how many times the current data of the previous sampling period should be used to compensate for the phase delays θa and θb.
[0049]
The attenuation constants βa and βb and the phase constants τa and τb obtained by the constant calculation unit 15 are displayed on the constant display unit 16 and stored in the storage unit 17. Then, the attenuation constants βa and βb and the phase constants τa and τb stored in the storage unit 17 are output from the correction output unit 18 to the relay determination calculation unit 9 and input from the

communication lines

5A and 5B in the relay determination calculation unit 9. The current at the other end is divided by the attenuation constants βa and βb from the calculation correction unit 12 and the relay determination calculation is performed using the past current data for the sampling period corresponding to the phase constants τa and τb. This compensates for attenuation and phase lag.
[0050]
【The invention's effect】
As described above, according to the present invention, the attenuation amount and the phase delay are measured, the attenuation constant and the phase constant of the input current at the other end are calculated, and these are compensated. A settling value that can prevent malfunction and malfunction can be set.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a ratio differential relay device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of a test circuit for obtaining an attenuation difference ΔI and a phase delay difference Δθ between two communication lines in the detection processing unit according to the embodiment of the present invention.
FIG. 3 is a configuration diagram of a test circuit in a case where an attenuation amount sum ΣI and a phase delay sum Σθ of two communication lines are obtained in the detection processing unit according to the embodiment of the present invention.
FIG. 4 is an overall configuration diagram of a protective relay system in which a conventional ratio differential relay device is applied to a long-distance power system.
FIG. 5 is a block diagram of a conventional ratio differential relay device 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Ratio differential relay device, 2 ... Instrument transformer, 3 ... Current limiting current transformer, 4 ... Insulation current transformer, 5 ... Communication line, 6 ... Circuit breaker, 7 ... Input conversion part, 8 ... A / D converter, 9 ... ratio current differential relay, 10 ... sequence processing unit, 11 ... output processing unit, 12 ... calculation correction unit, 13 ... detection processing unit, 14 ... display unit during measurement, 15 ... constant calculation unit, 16 ... Constant display section, 17 ... Storage section, 18 ... Correction output section, 19 ... Test power supply

Claims

Provided at both ends of the protection section of the power system, the current at the local end is input via a current transformer for the instrument, the current at the other end is input via a communication line, and the current between the local end and the current at the other end In a differential relay device that operates when the differential current exceeds an operation set value that increases in proportion to the passing current in the protection section, the current at the local end and the current at the other end are sampled at a predetermined cycle and digitally An A / D converter for converting into a quantity;
It operates when the difference current between the current at the local end and the current at the other end obtained by the A / D converter exceeds the operation set value, and operates when the difference current exceeds the operation set value. A relay determination calculation unit;
An output processing unit that outputs a trip signal to the circuit breakers at both ends of the protection section when the relay determination calculation unit operates;
A calculation correction unit that calculates a constant for compensating for attenuation and phase lag of the current at the other end by the communication line and adds correction to the determination calculation of the relay determination calculation unit, and
The calculation correction unit calculates the attenuation constant and the phase delay of the communication line, calculates the attenuation constant based on the attenuation obtained by the detection processing unit, and calculates the phase constant based on the phase delay A constant calculation unit, and a correction output unit that outputs the attenuation constant and the phase constant calculated by the writing constant calculation unit to the relay determination calculation unit,
The detection processing unit causes a test current to flow through the two communication lines in a state where the proportional differential relay devices at both ends are disconnected from the power system, and the attenuation difference, phase delay difference, and attenuation sum of the two communication lines. And a phase delay sum, and a ratio difference characterized in that an attenuation constant and a phase constant of the communication line are obtained based on an attenuation difference, a phase delay difference, an attenuation sum and a phase delay sum between the two communication lines. Relay device.

The relay determination calculation unit divides the current at the other end input from the communication line by the attenuation constant from the calculation correction unit as the current at the other end, and the past sampling period corresponding to the phase constant from the calculation correction unit. The ratio differential relay device according to claim 1, wherein the relay determination calculation is performed using current data .