JP3592565B2 - Frequency stabilization method and device for power system - Google Patents

Description

【０００５】
図５は周波数上昇時の安定と不安定の領域を示す特性図であり、中央演算装置４Ｎは、算出された周波数ΔＦが図５に示す安定領域に入っているか否かで各発電機の安定判別を行い、不安定となると判別した場合に、安定となるような遮断パターンに基づいて、情報信号伝送路８Ｂ，８Ｃを通して制御端末４Ｂ，４Ｃに指令し、制御端末４Ｂ，４Ｃは、コントロール・ケーブル７Ｂ、７Ｃを通して、遮断器６Ａまたは６Ｂにトリップ信号を出力し、過渡的な周波数上昇の最高値および落ち着き先を制御する。
尚、このような従来技術に関連した技術文献として「プラント特性を考慮した新しい系統安定化方式の開発と実用化」（電気学会電力技術研究会、平成６年１０月発行）がある。
【０００６】
【発明が解決しようとする課題】
従来の電力系統の周波数安定化装置は以上のように構成されているので、周波数安定化の手法は、発電機の系統定数Ｋ_ＨＧを求める際に、稼働発電機の慣性定数の総和Ｍ_ＯＧで正規化した制御対象系統内の総発電量（発電機の出力整定値）Ｐ_ＯＧから求めており、発電機の稼働時における実際の周波数応動特性に適応しておらず、また、発電機個々の周波数応動特性の違いを考慮していないため、系統状態に適応した最適な周波数制御が行えていないなどの課題があった。
【０００７】
この発明は上記のような課題を解決するためになされたもので、より系統構成に適応させて発電機の安定運転領域内に周波数を維持することができる電力系統の周波数安定化方法およびその装置を得ることを目的とする。
【０００８】
【課題を解決するための手段】
この発明に係る電力系統の周波数安定化方法は、分離された系統において発電過剰の不平衡が生じた場合に、需給アンバランス量、各発電機の速度調定率、および各発電機の調速器開度と負荷制限器開度との差に基づいて周波数上昇の落ち着き先周波数を求め、その落ち着き先周波数に応じて電源制限を行うものである。
【０００９】
この発明に係る電力系統の周波数安定化方法は、分離された系統において発電不足の不平衡が生じた場合に、需給アンバランス量、および各ガバナフリー機の出力増加量に基づいて周波数下降の最低周波数を求め、その最低周波数に応じて負荷制限を行うものである。
【００１０】
この発明に係る電力系統の周波数安定化方法は、分離された系統において発電過剰の不平衡が生じた場合に、発電機の出力検出値、発電機の慣性定数、需給アンバランス率、および発電機の定格出力に基づいて系統定数算出定数を求め、次に、その系統定数算出定数、および所定の定数に基づいて累乗近似した発電機の系統定数を求め、さらに、需給アンバランス量、発電機の出力整定値、および発電機の系統定数に基づいて周波数上昇の落ち着き先周波数を求め、その落ち着き先周波数に応じて電源制限を行うものである。
【００１１】
この発明に係る電力系統の周波数安定化方法は、分離された系統において発電過剰の不平衡が生じた場合に、発電機の出力検出値、発電機の慣性定数、需給アンバランス率、および発電機の定格出力に基づいて系統定数算出定数を求め、次に、需給アンバランス量によって場合分けされた定数、およびその系統定数算出定数に基づいて線形近似した発電機の系統定数を求め、さらに、需給アンバランス量、発電機の出力整定値、および発電機の系統定数に基づいて周波数上昇の落ち着き先周波数を求め、その落ち着き先周波数に応じて電源制限を行うものである。
【００１２】
この発明に係る電力系統の周波数安定化装置は、送電時に系統分断された場合に、連系線潮流値、各発電機の速度調定率、および各発電機の調速器開度と負荷制限器開度との差に基づいて周波数上昇の落ち着き先周波数を演算し、その落ち着き先周波数に応じて電源制限を行う演算制御手段を備えたものである。
【００１３】
この発明に係る電力系統の周波数安定化装置は、受電時に系統分断された場合に、連系線潮流値、および各ガバナフリー機の出力増加量に基づいて周波数下降の最低周波数を演算し、その最低周波数に応じて負荷制限を行う演算制御手段を備えたものである。
【００１４】
【発明の実施の形態】
以下、この発明の実施の一形態を説明する。
実施の形態１．
図１はこの発明の実施の形態１による電力系統の周波数安定化装置を示す構成図であり、図において、１Ａ，１Ｂは発電機（発電所）、２Ａ〜２Ｄは系統内の母線、３Ａ〜３Ｄは送電線であり、送電線３Ａは本系統（第１電力系統）と接続される他系統（第２電力系統）２０との連系線となる。
４Ａは計測用端末、４Ｂ〜４Ｅは制御端末、５は連系線ルート断検出用のセンサ（連系検出手段）であり、送電線３Ａの連系線潮流値および連系状態を検出するものである。６Ａ〜６Ｄは遮断器、７Ａ〜７Ｅはコントロール・ケーブル、８Ａ〜８Ｅ，８Ｎは情報信号伝送路、９は中央給電指令所、１０Ａ，１０Ｂは負荷である。
また、１４Ｎは中央演算装置（演算制御手段）であり、センサ５により送電線３Ａの連系線潮流値が本系統から他系統２０への送電時に系統分断されたと検出された場合に、周波数上昇の落ち着き先周波数を演算し、その落ち着き先周波数が発電機１Ａ，１Ｂの安定運転領域を外れる時に、発電機１Ａ，１Ｂの電源制限を行い、また、センサ５により送電線３Ａの連系線潮流値が他系統２０から本系統への受電時に系統分断されたと検出された場合に、周波数下降の最低周波数を演算し、その最低周波数が発電機１Ａ，１Ｂの安定運転領域を外れる時に、負荷１０Ａ，１０Ｂの負荷制限を行うものである。
【００１５】
次に動作について説明する。
送電線３Ａの連系状態は常時センサ５で検出され、コントロール・ケーブル７Ａを通して計測用端末４Ａに出力される。中央演算装置１４Ｎは、常に計測用端末４Ａから連系線潮流値および連系状態の情報を情報信号伝送路８Ａを通して取り込み、また、制御端末４Ｂ，４Ｃから情報信号伝送路８Ｂ，８Ｃを通して発電機１Ａ，１Ｂの発電情報を周期的に取り込み、さらに、中央給電指令所９から情報信号伝送路８Ｎを通して総負荷量の情報を周期的に取り込む。
また、中央演算装置１４Ｎは、必要に応じて電源制限信号、または負荷制限信号を情報信号伝送路８Ｂ〜８Ｅを通して制御端末４Ｂ〜４Ｅに出力し、制御端末４Ｂ〜４Ｅでは、電源制限信号あるいは負荷制限信号に応じて、受信した信号の内容から発電機１Ａ，１Ｂ、または負荷１０Ａ，１０Ｂを選択してトリップ信号を出力する。
例えば、送電線３Ａでルート断事故が発生した場合、センサ５からの情報からルート断事故を検出したことをキックとして、中央演算装置１４Ｎは起動状態に入り、電源制限、または負荷制限の安定化制御を行う。
【００１６】
図２は中央演算装置の動作を示すフローチャートであり、図に基づいて詳細な動作を説明する。
図２において、センサ５によりルート断事故が検出されれば中央演算装置１４Ｎは起動状態に入り（ステップＳＴ１）、故障発生時点を基準とする時刻リセットの処理を行い（ステップＳＴ２）、故障除去を検出する（ステップＳＴ３）。次に、センサ５により検出されていた連系線潮流値が本系統から見て送電か受電かを判定し（ステップＳＴ４）、送電であるならステップＳＴ５に、それ以外の時はステップＳＴ１１へ進む。
【００１７】
送電の場合は、センサ５により検出されていた連系線潮流値、各発電機１Ａ，１Ｂの速度調定率、各発電機１Ａ，１Ｂの調速器開度と負荷制限器開度との差（以下、Ｌ．Ｌ．幅と言う）を考慮して周波数上昇の落ち着き先周波数を求める（ステップＳＴ５）。そして、その周波数上昇の落ち着き先周波数が電源制限の必要な値を越えているか否かを判定し（ステップＳＴ６）、電源制限が必要であれば、安定化制御量（電源制限量）を予め決められたアルゴリズムによって決定する（ステップＳＴ７）。そして、決定した電源制限量に応じた発電機パターンが存在するか否かを判定し（ステップＳＴ８）、存在すれば決定した電源制限量に対応した遮断パターンを発電機１Ａ，１Ｂから選択し（ステップＳＴ９）、その決定した選択パターンに従って、情報信号伝送路８Ｂ，８Ｃを通して制御端末４Ｂ，４Ｃに情報を伝送し、制御端末４Ｂ，４Ｃから遮断器６Ａ，６Ｂにトリップ信号を出力することにより電源制限して（ステップＳＴ１０）、処理を終了する（ステップＳＴ１７）。
【００１８】
一方、受電の場合は、センサ５により検出されていた連系線潮流値、各発電機１Ａ，１Ｂのうちのガバナフリー機の出力増加量を考慮して周波数下降の最低周波数を求める（ステップＳＴ１１）。そして、その周波数下降の最低周波数が負荷制限の必要な値を下回っているか否かを判定し（ステップＳＴ１２）、負荷制限が必要であれば、安定化制御量（負荷制限量）を予め決められたアルゴリズムによって決定する（ステップＳＴ１３）。そして、決定した負荷制限量に応じた負荷パターンが存在するか否かを判定し（ステップＳＴ１４）、存在すれば決定した負荷制限量に対応した遮断パターンを負荷１０Ａ，１０Ｂから選択し（ステップＳＴ１５）、その決定した選択パターンに従って、情報信号伝送路８Ｄ，８Ｅを通して制御端末４Ｄ，４Ｅに情報を伝送し、制御端末４Ｄ，４Ｅから遮断器６Ｃ，６Ｄにトリップ信号を出力することにより負荷制限して（ステップＳＴ１６）、処理を終了する（ステップＳＴ１７）。
【００１９】
以上のように、この実施の形態１によれば、電力系統間の連系線ルート断時に認められる需給アンバランスによる周波数異常を事故発生後の発電機１Ａ，１Ｂの個々の周波数応動特性を考慮して演算するので、より精度の高い安定化制御が可能となる効果がある。
【００２０】
実施の形態２．
この実施の形態２は、送電時に連系線ルート断が発生した場合において、連系線潮流値、各発電機１Ａ，１Ｂの速度調定率、各発電機１Ａ，１ＢのＬ．Ｌ．幅を考慮して周波数上昇の落ち着き先周波数を求め、さらに、必要電源制限量を求める時の具体的な実施の形態について説明するものである。
【００２１】
次に動作について説明する。
図３は発電機特性と周波数との関係を示す特性図であり、系統の周波数は、発電機特性と負荷特性との交点で求めることができる。発電機がＬ．Ｌ．運転の場合、周波数がある程度変動しても発電機出力は変化しないため、発電機特性は図３（ａ）のようになり、周波数は図のＡ点となる。連系線潮流値が制御対象系統から見て送電であった場合に、連系線がルート断事故を起こすと、事故後の負荷特性が同図（ｂ）のように変化し、系統周波数は変化してΔＦ_１ （Ｂ点）に変化する。また、系統分断による発電機の出力変化ΔＰ_Ｇ は、以下の式（３）のようになる。
【００２２】
【数２】

【００２３】
また、周波数変動による負荷量の変化ΔＰ_Ｌ は、負荷の系統定数Ｋ_Ｌ より以下の式（４）で表される。
ΔＰ_Ｌ ＝Ｋ_Ｌ ・Ｐ_Ｌ ・ΔＦ_１ …（４）
ここに、Ｐ_Ｌ ：周波数変動前の負荷量
ガバナフリー機は、Ｌ＝０と考えれば良いため、系統全体として考える場合、式（３）、式（４）より系統周波数ΔＦ_１ は以下の式（５）で表される。
【００２４】
【数３】

【００２５】
しかし、式（５）は発電機、負荷の静特性から求めたものであり、周波数上昇時にはプラント側の応動により発電機出力を維持しようとする。図４は計算値と実際の周波数との関係を示す特性図であり、この図４に示すように計算値よりも実際の周波数が大きくなるので、プラント応動を考慮した等価的な各発電機の速度調定率Ｒ_ｉ および各発電機のＬ．Ｌ．幅Ｌ_ｉ を求めると共に、以下の式（６）で補正する。
ΔＦ_１Ｚ＝ａ・ΔＦ_１ ＋ｂ …（６）
ここに、ΔＦ_１Ｚ：補正後の系統周波数
つまり、式（６）の定数ａおよびｂを予めシミュレーションで設定しておけば、周波数上昇時の落ち着き先周波数を、系統の状態を考慮して高精度に演算することができる。
さらに、演算された補正後の系統周波数ΔＦ_{１ Ｚ} が、図５に示した安定領域に入っているか否かで安定判別を行い、不安定と判別した場合、安定となる遮断パターンで電源制限を行う。
【００２６】
以上のように、この実施の形態２によれば、電力系統間の連系線ルート断時に周波数が上昇する場合に、発電機１Ａ，１Ｂの個々の速度調定率Ｒ_ｉ 、およびＬ．Ｌ．幅Ｌ_ｉ を考慮して落ち着き先周波数と必要電源制限量を求めることができ、その結果、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００２７】
実施の形態３．
この実施の形態３は、受電時に連系線ルート断が発生した場合において、連系線潮流値、周波数下降の場合に認められるガバナフリー機の出力増加量を考慮して周波数下降の最低周波数を求め、さらに、必要負荷制限量を求める時の具体的な実施の形態について説明するものである。
【００２８】
次に動作について説明する。
図６は連系線ルート断時の周波数を示す特性図であり、連系線潮流が制御対象系統から見て受電であった場合に連系線がルート断事故を起こすと、系統周波数は図６（ｂ）のように推移し、その最低値ΔＦ_２ は以下のようにして演算することができる。
図７は発電機特性と周波数との関係を示す特性図であり、発電機の出力はガバナフリー機の場合にこの図７のようになり、系統分断により発電機の出力はＰ_Ｕ 増加し、出力増加量を考慮した場合の需給アンバランス率Ｒ_Ｕ は以下の式（７）のようになる。
【００２９】
【数４】

【００３０】
ここで、ガバナフリー機の出力増加量Ｐ_Ｕ は概ねガバナフリー容量の数十％であるが、プラントにより異なるため、予めシミュレーションで設定しておく。
図８は需給アンバランス率と周波数との関係を示す特性図であり、この図８に示すように、需給アンバランス率Ｒ_Ｕ と周波数の関係は以下の式（８）で示す一次関数で近似できる。
ΔＦ_２ ＝ａ・Ｒ_Ｕ ＋ｂ …（８）
また、負荷制限後の目標周波数をΔＦ_Ｌｓｅｔとすると、必要負荷制限量Ｐ_Ｌ は以下の式（９）で演算できる。
【００３１】
【数５】

【００３２】
つまり、式（７）のガバナフリー機の出力増加量Ｐ_Ｕ と式（８）の定数ａおよびｂを予め設定しておけば、周波数下降時の過渡的な最低値を系統の状態を考慮して演算することができ、式（９）から必要負荷制限量を容易に演算することができる。
【００３３】
以上のように、この実施の形態３によれば、電力系統間の連系線ルート断時に各ガバナフリー機の出力増加量を考慮して周波数下降時の過渡的な最低値と必要負荷制限量を求めることができ、その結果、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００３４】
実施の形態４．
この実施の形態４は、送電時に連系線ルート断が発生した場合において、発電機の出力検出値に基づいて演算された発電機の系統定数を用いて周波数上昇の落ち着き先周波数を求め、さらに、必要電源制限量を求める時の実施の形態について説明するものである。
【００３５】
次に動作について説明する。
連系線潮流値が制御対象系統からみて送電であった場合に連系線がルート断事故を起こすと、系統周波数は図６（ａ）のような波形を示し、その落ち着き先周波数ΔＦ_１ は以下の式（１０）より演算することができる。
【００３６】
【数６】

【００３７】
ここで、負荷の系統定数Ｋ_Ｌ は、従来技術と同様に予め適当な手段によって求めておくこととし、発電機の系統定数Ｋ_Ｈ は以下のように求める。
発電機の系統定数Ｋ_Ｈ は、制御対象内の発電機の稼動状態によって左右されるため、図９（ａ）に示すように、以下の式（１１）で表される系統定数算出定数Ｘで発電機の系統定数を表すと、以下の式（１２）で累乗近似できる。
【００３８】
【数７】

【００３９】
ここで、発電機の出力検出値Ｐ_ＯＧは、制御端末４Ｂ，４Ｃから情報信号伝送路８Ｂ，８Ｃを通して発電機１Ａ，１Ｂの発電情報として周期的に取り込むことによって得られるものである。
また、図９（ｂ）に示すように、系統定数算出定数Ｘを需給アンバランス率に応じて場合分けを行うことによって、発電機の系統定数Ｋ_Ｈ は以下の式（１３）で線形近似できる。
Ｋ_Ｈ ＝ａ_２ ・Ｘ＋ｂ_２ （０≦Ｘ＜Ｃ_１ ）
Ｋ_Ｈ ＝ａ_３ ・Ｘ＋ｂ_３ （Ｃ_１ ≦Ｘ＜Ｃ_２ ）
Ｋ_Ｈ ＝ａ_４ ・Ｘ＋ｂ_４ （Ｘ≧Ｃ_２ ） …（１３）
ここに、ａ_２ 〜ａ_４ ，ｂ_２ 〜ｂ_４ ，Ｃ_１ ，Ｃ_２ ：定数
つまり、式（１２）の係数ａ_１ およびｂ_１ 、または式（１３）のａ_２ 〜ａ_４ 、ｂ_２ 〜ｂ_４ 、およびＣ_１ ，Ｃ_２ を予めシミュレーションで設定しておけば、発電機の系統定数Ｋ_Ｈ は演算することができ、さらに、式（１０）から容易に落ち着き先周波数ΔＦ_１ を演算することができる。また、演算されたΔＦ_１ が図５に示す安定領域に入っているか否かで安定判別を行い、不安定と判別した場合、安定となる遮断パターンで電源制限を行う。
【００４０】
以上のように、この実施の形態４によれば、電力系統間の連系線ルート断時に周波数が上昇する場合に、発電機の出力検出値Ｐ_ＯＧに基づいて演算された発電機の系統定数Ｋ_Ｈ を用いて落ち着き先周波数と必要電源制限量を求めることができ、その結果、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４１】
【発明の効果】
以上のように、この発明によれば、各発電機の速度調定率、および各発電機の調速器開度と負荷制限器開度との差に基づいて周波数上昇の落ち着き先周波数を求めるように構成したので、その求められた落ち着き先周波数に応じて電源制限を行えば、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４２】
この発明によれば、各ガバナフリー機の出力増加量に基づいて周波数下降の最低周波数を求めるように構成したので、その求められた最低周波数に応じて負荷制限を行えば、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４３】
この発明によれば、発電機の出力検出値に基づいて系統定数算出定数を求め、その系統定数算出定数、および所定の定数に基づいて累乗近似した発電機の系統定数を求め、さらに、需給アンバランス量、発電機の出力整定値、および発電機の系統定数に基づいて周波数上昇の落ち着き先周波数を求めるように構成したので、その求められた落ち着き先周波数に応じて電源制限を行えば、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４４】
この発明によれば、発電機の出力検出値に基づいて系統定数算出定数を求め、需給アンバランス量によって場合分けされた定数、およびその系統定数算出定数に基づいて線形近似した発電機の系統定数を求め、さらに、需給アンバランス量、発電機の出力整定値、および発電機の系統定数に基づいて周波数上昇の落ち着き先周波数を求めるように構成したので、その求められた落ち着き先周波数に応じて電源制限を行えば、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４５】
この発明によれば、各発電機の速度調定率、および各発電機の調速器開度と負荷制限器開度との差に基づいて周波数上昇の落ち着き先周波数を演算し、その落ち着き先周波数に応じて電源制限を行う演算制御手段を備えるように構成したので、送電時に系統分断されたと検出された場合において、系統状態に適応した最適な周波数制御が可能となる効果がある。
【００４６】
この発明によれば、各ガバナフリー機の出力増加量に基づいて周波数下降の最低周波数を演算し、その最低周波数に応じて負荷制限を行う演算制御手段を備えるように構成したので、受電時に系統分断されたと検出された場合において、系統状態に適応した最適な周波数制御が可能となる効果がある。
【図面の簡単な説明】
【図１】この発明の実施の形態１による電力系統の周波数安定化装置を示す構成図である。
【図２】中央演算装置の動作を示すフローチャートである。
【図３】発電機特性と周波数との関係を示す特性図である。
【図４】計算値と実際の周波数との関係を示す特性図である。
【図５】周波数上昇時の安定と不安定の領域を示す特性図である。
【図６】連系線ルート断時の周波数を示す特性図である。
【図７】発電機特性と周波数との関係を示す特性図である。
【図８】需給アンバランス率と周波数との関係を示す特性図である。
【図９】系統定数算出定数と系統定数との関係を示す特性図である。
【図１０】従来の電力系統の周波数安定化装置を示す構成図である。
【符号の説明】
１Ａ，１Ｂ 発電機、５ センサ（連系検出手段）、１０Ａ，１０Ｂ 負荷、１４Ｎ 中央演算装置（演算制御手段）、２０ 他系統（第２電力系統）。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a frequency stabilization method for a power system and a device for controlling the frequency abnormality, which is recognized when the power system is separated due to the occurrence of system division, by limiting the power supply or the load.
[0002]
[Prior art]
FIG. 10 is a configuration diagram showing a conventional frequency stabilizing device for an electric power system. In the figure, 1A and 1B are generators (power stations), 2A to 2D are buses in the system, and 3A to 3D are transmission lines. The transmission line 3A is a connection line with another system 20 connected to the main system.
4A is a measuring terminal, 4B to 4E are control terminals, 4N is a central processing unit, 5 is a sensor for detecting disconnection of the interconnection route, which detects the interconnection flow of the transmission line 3A and the interconnection state. It is. 6A to 6D are circuit breakers, 7A to 7E are control cables, 8A to 8E and 8N are information signal transmission lines, 9 is a central power supply command center, and 10A and 10B are loads.
[0003]
Next, the operation will be described.
When a transmission line route disconnection accident occurs during transmission flow of the transmission line 3A toward another system 20 connected to the main system, the sensor 5 detects the connection line route disconnection accident of the transmission line 3A. Then, the signal is transmitted to the measuring terminal 4A through the control cable 7A, and the measuring terminal 4A transmits the signal to the central processing unit 4N through the information signal transmission line 8A.
The central processing unit 4N, which has recognized that the interconnection line route disconnection accident has occurred, obtains the following information from the interconnection line power flow value transmitted so far by the detection of the sensor 5 and the information from the central power supply command center 9 as follows. The system constant of the generator is calculated by the equation (1), and then the rising frequency ΔF is calculated by the following equation (2) based on the calculated system constant of the generator.
[0004]
(Equation 1)

[0005]
FIG. 5 is a characteristic diagram showing a region of stability and instability when the frequency rises. The central processing unit 4N determines whether each of the generators has a stability by determining whether the calculated frequency ΔF falls within the stability region shown in FIG. When it is determined that the operation becomes unstable, the control terminals 4B and 4C are instructed through the information signal transmission lines 8B and 8C based on the cutoff pattern that makes the operation stable. The trip signal is output to the circuit breaker 6A or 6B through the cables 7B and 7C, and the maximum value of the transient frequency rise and the destination of the calm are controlled.
Incidentally, as a technical document related to such a conventional technique, there is “Development and practical application of a new system stabilization method in consideration of plant characteristics” (IEE of the Institute of Electric Power Technology, published in October 1994).
[0006]
[Problems to be solved by the invention]
Since the conventional power system frequency stabilization device is configured as described above, the frequency stabilization method is based on the sum of the inertia constants M _OG of the operating generator when calculating the system constant K _HG of the generator. total generation of the control object in system normalized and obtained from P _OG (output setting value of the generator), not adapted to the actual frequency response characteristics at operation of the generator, also, the generator of the individual Since differences in frequency response characteristics are not taken into account, there has been a problem that optimal frequency control adapted to the system state cannot be performed.
[0007]
The present invention has been made in order to solve the above-described problems, and a frequency stabilizing method and apparatus for a power system capable of maintaining a frequency within a stable operation region of a generator by adapting to a system configuration more. The purpose is to obtain.
[0008]
[Means for Solving the Problems]
The frequency stabilization method for an electric power system according to the present invention is characterized in that, when unbalance of excess power generation occurs in a separated system, a supply-demand imbalance amount, a speed regulation rate of each generator, and a governor of each generator Based on the difference between the opening and the load limiter opening, the destination frequency of the frequency increase is determined, and the power source is limited according to the destination frequency.
[0009]
The frequency stabilization method for an electric power system according to the present invention is characterized in that when an unbalance due to power generation shortage occurs in a separated system, a supply and demand imbalance amount, and a minimum frequency decrease based on an increase amount of output of each governor-free machine. The frequency is obtained, and the load is limited according to the lowest frequency.
[0010]
The frequency stabilization method for an electric power system according to the present invention provides a method for detecting a generator output, an inertia constant of a generator, a supply / demand imbalance rate, and The system constant calculation constant is obtained based on the rated output of the generator, then the system constant calculation constant, and the system constant of the generator approximated to the power is calculated based on the predetermined constant. The frequency at which the frequency rises is settled is determined based on the output set value and the system constant of the generator, and the power supply is limited according to the frequency at which the frequency settles.
[0011]
The frequency stabilization method for an electric power system according to the present invention provides a method for detecting a generator output, an inertia constant of a generator, a supply / demand imbalance rate, and Then, a system constant calculation constant is calculated based on the rated output of the generator, then a constant classified according to the supply-demand imbalance amount, and a system constant of the generator which is linearly approximated based on the system constant calculation constant are obtained. The frequency at which the frequency rises is settled is determined based on the unbalance amount, the output setting value of the generator, and the system constant of the generator, and the power supply is limited according to the settled frequency.
[0012]
The power system frequency stabilizing device according to the present invention is configured such that, when the power system is disconnected during power transmission, the interconnection line power flow value, the speed regulation rate of each generator, the governor opening of each generator, and the load limiter An operation control means is provided for calculating a settling frequency of the frequency rise based on a difference from the opening degree, and for limiting a power supply according to the settling frequency.
[0013]
The frequency stabilizing device for an electric power system according to the present invention, when the power system is disconnected at the time of receiving power, calculates the interconnection line power flow value, and the lowest frequency of the frequency drop based on the output increase amount of each governor-free machine, It is provided with arithmetic control means for limiting the load according to the lowest frequency.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a frequency stabilizing device for a power system according to Embodiment 1 of the present invention. In the figure, 1A and 1B are generators (power plants), 2A to 2D are buses in the system, and 3A to 3D. 3D is a transmission line, and the transmission line 3A is a connection line with another system (second power system) 20 connected to the main system (first power system).
4A is a measuring terminal, 4B to 4E are control terminals, and 5 is a sensor (interconnection detecting means) for detecting the disconnection of the interconnection route, which detects the interconnection flow of the transmission line 3A and the interconnection state. It is. 6A to 6D are circuit breakers, 7A to 7E are control cables, 8A to 8E and 8N are information signal transmission lines, 9 is a central power supply command center, and 10A and 10B are loads.
Reference numeral 14N denotes a central processing unit (arithmetic control means), which increases the frequency when the sensor 5 detects that the power flow value of the interconnection line of the transmission line 3A has been disconnected during power transmission from this system to the other system 20. Is calculated, and when the settled frequency is out of the stable operation range of the generators 1A and 1B, the power supply of the generators 1A and 1B is limited. When it is detected that the power supply is disconnected from the other system 20 to the main system, the lowest frequency of the frequency drop is calculated, and when the lowest frequency is out of the stable operation region of the generators 1A and 1B, the load 10A , 10B.
[0015]
Next, the operation will be described.
The interconnection state of the transmission line 3A is always detected by the sensor 5 and output to the measurement terminal 4A through the control cable 7A. The central processing unit 14N always takes in the power flow value of the interconnection line and the information of the interconnection state from the measuring terminal 4A through the information signal transmission line 8A, and the generator from the control terminals 4B and 4C through the information signal transmission lines 8B and 8C. The power generation information of 1A and 1B is periodically taken in, and further, the information of the total load is periodically taken in from the central power supply commanding station 9 through the information signal transmission line 8N.
Further, the central processing unit 14N outputs a power limiting signal or a load limiting signal to the control terminals 4B to 4E through the information signal transmission lines 8B to 8E as necessary, and the control terminals 4B to 4E output the power limiting signal or the load limiting signal. According to the limit signal, the generator 1A, 1B or the load 10A, 10B is selected from the content of the received signal and a trip signal is output.
For example, when a route disconnection accident occurs in the transmission line 3A, the central processing unit 14N enters a start-up state, and the detection of the route disconnection accident from the information from the sensor 5 takes a kick to stabilize the power supply limitation or the load limitation. Perform control.
[0016]
FIG. 2 is a flowchart showing the operation of the central processing unit, and the detailed operation will be described based on the drawing.
In FIG. 2, when a route disconnection accident is detected by the sensor 5, the central processing unit 14N enters a start-up state (step ST1), performs a time reset process based on the time of occurrence of a failure (step ST2), and removes the failure. Detect (Step ST3). Next, it is determined whether the power flow value detected by the sensor 5 is power transmission or power reception from the viewpoint of this system (step ST4). If the power transmission is power transmission, the process proceeds to step ST5. Otherwise, the process proceeds to step ST11. .
[0017]
In the case of power transmission, the tidal current value detected by the sensor 5, the speed regulation rate of each generator 1A, 1B, and the difference between the governor opening and the load limiter opening of each generator 1A, 1B. (Hereinafter, referred to as LL width), a frequency at which the frequency rises is settled is determined (step ST5). Then, it is determined whether or not the frequency to which the frequency rise has settled exceeds the value required for power supply restriction (step ST6). If power supply restriction is required, a stabilization control amount (power supply restriction amount) is determined in advance. It is determined by the given algorithm (step ST7). Then, it is determined whether or not a generator pattern corresponding to the determined power supply restriction amount exists (step ST8). If there is, a cutoff pattern corresponding to the determined power supply restriction amount is selected from the generators 1A and 1B ( Step ST9) According to the selected selection pattern, information is transmitted to the control terminals 4B and 4C through the information signal transmission lines 8B and 8C, and a trip signal is output from the control terminals 4B and 4C to the circuit breakers 6A and 6B, so that the power is supplied. The process is restricted (step ST10), and the process ends (step ST17).
[0018]
On the other hand, in the case of power reception, the lowest frequency of the frequency drop is determined in consideration of the interconnection flow detected by the sensor 5 and the output increase of the governor-free machine among the generators 1A and 1B (step ST11). ). Then, it is determined whether or not the lowest frequency of the frequency drop is lower than a value required for load limitation (step ST12). If load limitation is required, a stabilization control amount (load limit amount) is determined in advance. (Step ST13). Then, it is determined whether or not a load pattern corresponding to the determined load limit exists (step ST14). If there is, a cutoff pattern corresponding to the determined load limit is selected from the loads 10A and 10B (step ST15). According to the determined selection pattern, information is transmitted to the control terminals 4D and 4E through the information signal transmission lines 8D and 8E, and the load is limited by outputting a trip signal from the control terminals 4D and 4E to the circuit breakers 6C and 6D. (Step ST16), and terminates the process (step ST17).
[0019]
As described above, according to the first embodiment, the frequency abnormality due to the supply-demand imbalance observed when the interconnection route between the electric power systems is disconnected is considered in consideration of the individual frequency response characteristics of the generators 1A and 1B after the occurrence of the accident. Therefore, there is an effect that more accurate stabilization control can be performed.
[0020]
Embodiment 2 FIG.
In the second embodiment, when an interconnecting line route break occurs during power transmission, the interconnecting line power flow value, the speed regulation rate of each of the generators 1A and 1B, and the L.R. L. A specific embodiment will be described in which a settled frequency of a frequency rise is determined in consideration of a width, and a required power supply limit amount is further determined.
[0021]
Next, the operation will be described.
FIG. 3 is a characteristic diagram showing the relationship between the generator characteristics and the frequency. The frequency of the system can be obtained at the intersection of the generator characteristics and the load characteristics. If the generator is L. L. In the case of operation, since the generator output does not change even if the frequency fluctuates to some extent, the generator characteristics are as shown in FIG. 3A, and the frequency is point A in the figure. If the power flow of the interconnecting line is power transmission as viewed from the control target system, and the interconnecting line causes a route disconnection accident, the load characteristics after the accident will change as shown in FIG. It changes to ΔF ₁ (point B). Also, the output variation [Delta] P _G of the generator by line cutting is given by the following equation (3).
[0022]
(Equation 2)

[0023]
The change [Delta] P _L of the load amount due to the frequency fluctuations is expressed by the following equation from the system constant K _L of the load (4).
ΔP _L = K _L · P _L · ΔF ₁ (4)
Here, P _L : the load governor-free machine before the frequency change can be considered as L = 0. Therefore, when considering the entire system, the system frequency ΔF ₁ is obtained from the following formulas from Expressions (3) and (4). It is represented by (5).
[0024]
(Equation 3)

[0025]
However, equation (5) is obtained from the static characteristics of the generator and the load, and attempts to maintain the generator output by the response of the plant when the frequency increases. FIG. 4 is a characteristic diagram showing the relationship between the calculated value and the actual frequency. As shown in FIG. 4, since the actual frequency is larger than the calculated value, the equivalent of each generator considering the plant response is considered. Speed regulation rate R _i and L.V. L. The width _Li is obtained, and is corrected by the following equation (6).
ΔF _1Z = a · ΔF ₁ + b (6)
Here, ΔF _1Z : the corrected system frequency, that is, if the constants a and b in the equation (6) are set in advance by simulation, the settled frequency at the time of frequency increase can be calculated with high accuracy in consideration of the state of the system. Can be calculated.
Further, a stability determination is performed based on whether the calculated corrected system frequency ΔF _{1 Z} falls within the stable region shown in FIG. 5, and when it is determined that the system frequency is unstable, the power supply is restricted by a stable cutoff pattern. Do.
[0026]
As described above, according to the second embodiment, when the frequency increases at the time of disconnection of the interconnection route between the power systems, the individual speed regulation rates R _i and L. L. Width L _i can be determined in consideration with restless-to frequency and the required power limit amount, so that the effect of the possible optimum frequency control adapted to the system state.
[0027]
Embodiment 3 FIG.
In the third embodiment, when the interconnection line route breaks during power reception, the lowest frequency of the frequency decrease is considered in consideration of the interconnection line power flow value and the increase in the output of the governor-free machine that is recognized in the case of the frequency decrease. A specific embodiment for obtaining the required load limiting amount will be described.
[0028]
Next, the operation will be described.
FIG. 6 is a characteristic diagram showing the frequency at the time of disconnection of the interconnection line route. When the interconnection line causes a route disconnection accident when the interconnection flow is power receiving from the control target system, the system frequency is shown in FIG. 6B, and the minimum value ΔF ₂ can be calculated as follows.
Figure 7 is a characteristic diagram showing the relationship between the generator characteristics and the frequency, the output of the generator is as shown in FIG. 7 in the case of the governor free machine, the output of the generator by line cutting increases P _U, supply and demand imbalance rate R _U in the case of considering the output increment is represented by the following formula (7).
[0029]
(Equation 4)

[0030]
Here, the output increasing amount P _U of governor-free machine is approximately several tens of percent of the governor-free capacity, because it varies by plants, is set in advance by simulation.
FIG. 8 is a characteristic diagram showing the relationship between the supply and demand unbalance rate and the frequency. As shown in FIG. 8, the relationship between the supply and demand unbalance rate _RU and the frequency is approximated by a linear function expressed by the following equation (8). it can.
ΔF ₂ = a · R _U + b (8)
Further, when the target frequency after load limiting and [Delta] F _Lset, necessary load shedding amount P _L can be calculated by the following equation (9).
[0031]
(Equation 5)

[0032]
In other words, by setting the constants a and b of Formula output increase in governor-free machine (7) P _U and equation (8) in advance, the transient minimum value at a frequency lowering considering the state of the system The required load limiting amount can be easily calculated from equation (9).
[0033]
As described above, according to the third embodiment, the transient minimum value and the required load limiting amount at the time of frequency drop are considered in consideration of the output increase amount of each governor-free machine when the interconnection line route between the power systems is broken. Is obtained, and as a result, there is an effect that optimal frequency control adapted to the system state can be performed.
[0034]
Embodiment 4 FIG.
In the fourth embodiment, when the interconnection line route breaks during power transmission, the settled frequency of the frequency rise is obtained using the system constant of the generator calculated based on the output detection value of the generator. An embodiment for obtaining a required power supply restriction amount will be described.
[0035]
Next, the operation will be described.
If the interconnecting line causes a route disconnection accident when the interconnecting line power flow value is power transmission from the viewpoint of the control target system, the system frequency shows a waveform as shown in FIG. 6 (a), and the destination frequency ΔF ₁ becomes It can be calculated from the following equation (10).
[0036]
(Equation 6)

[0037]
Here, the system constant K _L of the load is determined in advance by appropriate means as in the prior art, and the system constant K _H of the generator is determined as follows.
Since the system constant K _H of the generator depends on the operating state of the generator in the control target, as shown in FIG. 9A, the system constant K _H is represented by a system constant calculation constant X expressed by the following equation (11). Expressing the system constant of the generator, power approximation can be obtained by the following equation (12).
[0038]
(Equation 7)

[0039]
Here, the output detection value P _OG of the generator is obtained control terminal 4B, information signal transmission path through 8B 4C, the generator 1A through 8C, by incorporating periodically as a generator information 1B.
Further, as shown in FIG. 9 (b), by performing case analysis according lineage constant calculating constants X in supply and demand imbalance rate, system constants K _H of the generator can be linearly approximated by the following equation (13) .
K _H = a ₂ · X + b ₂ (0 ≦ X <C ₁ )
K _H = a ₃ · X + b ₃ (C ₁ ≦ X <C ₂ )
K _H = a ₄ × X + b ₄ (X ≧ C ₂ ) (13)
Here, a _{2 to} a ₄ , b _{2 to} b ₄ , C ₁ , C ₂ : constants, that is, coefficients a ₁ and b _{1 in} equation (12), or a _{2 to} a ₄ , b _{2 in} equation (13) If b ₄ , C ₁ , and C ₂ are set in advance by simulation, the system constant K _H of the generator can be calculated, and the calm down destination frequency ΔF ₁ can be easily calculated from Expression (10). can do. The stability is determined based on whether or not the calculated ΔF ₁ is in the stable region shown in FIG. 5. If it is determined that the calculated ΔF ₁ is unstable, the power supply is limited in a stable cutoff pattern.
[0040]
As described above, according to the fourth embodiment, when the frequency rises when the interconnection line route between the electric power systems is _broken , the system constant of the generator calculated based on the output detection value _POG of the generator K _H can be obtained calm destination frequency and the required power restriction rate using, as a result, there is an effect that it becomes possible optimum frequency control adapted to the system state.
[0041]
【The invention's effect】
As described above, according to the present invention, the settled frequency of the frequency increase is determined based on the speed regulation rate of each generator and the difference between the governor opening and the load limiter opening of each generator. Therefore, if the power supply is restricted in accordance with the determined destination frequency, there is an effect that optimal frequency control adapted to the system state can be performed.
[0042]
According to the present invention, since the lowest frequency of the frequency decrease is determined based on the output increase amount of each governor-free machine, if the load is limited according to the determined lowest frequency, the system is adapted to the system state. There is an effect that optimal frequency control can be performed.
[0043]
According to the present invention, a system constant calculation constant is determined based on the output detection value of the generator, the system constant calculation constant is determined based on the system constant calculation constant, and a system constant of the generator approximated to the power is determined based on the predetermined constant. Since the settled frequency of the frequency rise is calculated based on the balance amount, the output setting value of the generator, and the system constant of the generator, if the power supply is limited according to the calculated settled frequency, the system There is an effect that optimal frequency control adapted to the state can be performed.
[0044]
According to the present invention, a system constant calculation constant is obtained based on the output detection value of the generator, the constant classified according to the supply-demand imbalance amount, and the system constant of the generator linearly approximated based on the system constant calculation constant. Further, since the supply and demand imbalance amount, the output settling value of the generator, and the settled frequency of the frequency rise based on the system constant of the generator is obtained, according to the obtained settled frequency. If the power supply is restricted, there is an effect that optimal frequency control adapted to the system state can be performed.
[0045]
According to the present invention, the settling frequency of the frequency rise is calculated based on the speed regulation rate of each generator, and the difference between the governor opening and the load limiter opening of each generator, and the settling frequency is calculated. Is provided so as to provide a power control in accordance with the above condition, so that when it is detected that the power system has been disconnected at the time of power transmission, there is an effect that optimal frequency control adapted to the system state can be performed.
[0046]
According to the present invention, the system is configured to calculate the lowest frequency of the frequency drop based on the output increase amount of each governor-free machine, and to have the calculation control means for performing load limitation according to the lowest frequency. When it is detected that the power supply is divided, there is an effect that optimal frequency control adapted to the system state can be performed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a frequency stabilization device for an electric power system according to a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating an operation of the central processing unit.
FIG. 3 is a characteristic diagram showing a relationship between a generator characteristic and a frequency.
FIG. 4 is a characteristic diagram showing a relationship between a calculated value and an actual frequency.
FIG. 5 is a characteristic diagram showing a stable and unstable region when the frequency is increased.
FIG. 6 is a characteristic diagram showing a frequency when the interconnection line route is disconnected.
FIG. 7 is a characteristic diagram showing a relationship between a generator characteristic and a frequency.
FIG. 8 is a characteristic diagram showing a relationship between a supply and demand unbalance rate and a frequency.
FIG. 9 is a characteristic diagram showing a relationship between a system constant calculation constant and a system constant.
FIG. 10 is a configuration diagram showing a conventional power system frequency stabilization device.
[Explanation of symbols]
1A, 1B generators, 5 sensors (interconnection detection means), 10A, 10B loads, 14N central processing unit (operation control means), 20 other systems (second power system).

Claims (6)

When the power system is disconnected and the unbalance of excess power generation of the generators occurs between the power generation and the load of the multiple generators in the separated system, the power generation of the multiple generators Of the frequency rise and fall, based on the imbalance between the supply and demand, the speed regulation rate of each generator, and the difference between the governor opening and the load limiter opening of each generator. And a power system frequency stabilizing method for limiting the power supply of the plurality of generators when the settled frequency is out of the stable operation range of the plurality of generators. If the power system is disconnected from the power system and there is an imbalance in the power generation shortage of the generators between the power generation and the load of the multiple generators in the separated system, the power generation of the multiple generators The minimum frequency of the frequency decrease is determined based on the supply-demand imbalance between the load and the load, and the output increase of each governor-free machine among the plurality of generators, and the lowest frequency determines the stable operation of the plurality of generators. A method for stabilizing the frequency of a power system in which a load is limited when the power goes out of a range. When the power system is disconnected and the unbalance of excess power generation of the generators occurs between the power generation and load of the multiple generators in the separated system, the output of the multiple generators is detected. The system constant calculation constant is calculated based on the values, the inertia constants of the plurality of generators, the supply / demand imbalance ratio between the power generation and the load of the plurality of generators, and the rated output of the plurality of generators. Calculates the system constant of the generator which is approximated to the power based on the system constant calculation constant and the predetermined constant, further obtains the supply and demand imbalance between the power generation amount and the load amount of the plurality of generators, The settled frequency of the frequency increase is determined based on the output set value of the above and the system constant of the generator, and when the settled frequency is out of the stable operation range of the plurality of generators, the power supply of the plurality of generators is determined. Frequency stabilization method for a power system performing the limit. When the power system is disconnected and the unbalance of excess power generation of the generators occurs between the power generation and load of the multiple generators in the separated system, the output of the multiple generators is detected. The system constant calculation constant is calculated based on the values, the inertia constants of the plurality of generators, the supply / demand imbalance ratio between the power generation and the load of the plurality of generators, and the rated output of the plurality of generators. The system constants of the generators are obtained by linearly approximating the system constants of the generators based on the supply and demand imbalance between the power generation amount and the load amount of the plurality of generators, and the system constant calculation constants. Based on the balance amount, the output set values of the plurality of generators, and the system constants of the generators, the settled frequency of the frequency increase is obtained, and the settled frequency is the stable operation area of the plurality of generators. When disengaged, the frequency stabilization method for a power system performing power restriction of the plurality of generators. Interconnection detection means for detecting an interconnection flow value and an interconnection state between a first electric power system to which a plurality of generators and loads are connected and a second electric power system other than the first electric power system; If the grid detection means detects that the grid flow has been disconnected during transmission from the first power system to the second power grid, the grid flow and the speed regulation rate of each generator Calculates the settled frequency of the frequency increase based on the difference between the governor opening of each generator and the load limiter opening, and the settled frequency is out of the stable operation region of the plurality of generators. A frequency stabilizing device for an electric power system, comprising: an arithmetic control unit for restricting the power supply of the plurality of generators. Interconnection detection means for detecting an interconnection flow value and an interconnection state between a first electric power system to which a plurality of generators and loads are connected and a second electric power system other than the first electric power system; When it is detected by the system detection means that the power flow value of the interconnection line has been disconnected at the time of receiving power from the second power system to the first power system, the power flow value of the interconnection line and each of the plurality of generators A power control system that calculates a lowest frequency of the frequency decrease based on the output increase amount of the governor-free machine and, when the lowest frequency is out of the stable operation region of the generator, a calculation control unit that performs load limitation on the load. Frequency stabilizer.

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