JPH085679A - Method and apparatus for detecting frequency and power system stabilization system - Google Patents
Method and apparatus for detecting frequency and power system stabilization systemInfo
- Publication number
- JPH085679A JPH085679A JP6135586A JP13558694A JPH085679A JP H085679 A JPH085679 A JP H085679A JP 6135586 A JP6135586 A JP 6135586A JP 13558694 A JP13558694 A JP 13558694A JP H085679 A JPH085679 A JP H085679A
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- Prior art keywords
- frequency
- zero point
- sampling
- time difference
- detecting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Measuring Frequencies, Analyzing Spectra (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、周波数検出装置に係
り、特に電力系統における交流入力量の周波数検出方式
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency detecting device, and more particularly to a frequency detecting method for an AC input amount in a power system.
【０００２】[0002]
【従来の技術】電力系統における交流量の周波数検出方
法として、特公昭６３−４６６４８号公報等に明らかな
ように、交流量の零点の直前、直後のサンプリング値か
ら直線近似により零点を求める方式が周知である。この
改良案として、特開昭５７−１２９１２６号公報に開示
のように、零点を検出する度に、その零点から過去の任
意倍数半サイクル前の零点までの時間を求めて、周波数
の検出精度を向上する方法がある。2. Description of the Related Art As a frequency detection method for an alternating current amount in a power system, as is apparent from Japanese Patent Publication No. 63-46648, there is a method of obtaining a zero point by linear approximation from sampling values immediately before and after the zero point of the alternating current amount. It is well known. As a proposal for this improvement, as disclosed in Japanese Patent Laid-Open No. 57-129126, each time a zero point is detected, the time from the zero point to the zero point before the arbitrary multiple half cycle in the past is calculated to improve the frequency detection accuracy. There are ways to improve.
【０００３】一方、直線近似によらない周波数検出方法
として、特開平２−１８７６６９号公報などに記載のよ
うに、複数のサンプリング値を入力として逆三角関数演
算により周波数を求めるものが公知である。On the other hand, as a frequency detecting method that does not rely on linear approximation, a method is known in which a frequency is calculated by an inverse trigonometric function operation with a plurality of sampling values as inputs, as described in Japanese Patent Laid-Open No. 2-187669.
【０００４】[0004]
【発明が解決しようとする課題】直線近似による方法
は、零点前後のサンプリング値から直接に零点を求める
ために、周波数が５％変化した場合の演算誤差が約０．
０６％とその検出精度が低く、周波数変化幅の検出など
には困難があった。In the method based on the linear approximation, since the zero point is directly obtained from the sampling values around the zero point, the calculation error when the frequency changes by 5% is about 0.
The detection accuracy was low at 06%, and it was difficult to detect the frequency change width.
【０００５】一方、上記した逆三角関数による方法は、
半周期に３〜５点の入力サンプリング値を必要とするの
で、その値にピークの近傍を含むことが多い。交流量の
測定を共用する場合には、特定の用途の検出精度をあげ
るためにフルスケールを低く抑えることがあり、交流波
形によってはピークの近傍がＡ／Ｄ変換部のフルスケー
ルを超えてしまうことがある。しかし、１点でもフルス
ケールを超えた場合は、周波数の測定が不可能になると
いう問題点がある。On the other hand, the method using the above-mentioned inverse trigonometric function is
Since the input sampling value of 3 to 5 points is required for a half cycle, the value often includes the vicinity of the peak. When the measurement of the AC amount is shared, the full scale may be kept low in order to improve the detection accuracy for a specific application, and the peak vicinity may exceed the full scale of the A / D converter depending on the AC waveform. Sometimes. However, if even one point exceeds the full scale, there is a problem that the frequency cannot be measured.
【０００６】本発明の目的は、上記した従来の直線近似
方式と逆三角関数方式の問題点を克服し、測定不能を生
じることなく高精度で信頼性の高い周波数検出方法及び
装置を提供することにある。An object of the present invention is to overcome the above-mentioned problems of the conventional linear approximation method and inverse trigonometric function method, and to provide a highly accurate and highly reliable frequency detection method and apparatus without causing measurement failure. It is in.
【０００７】本発明の他の目的は、系統周波数を高速且
つ高精度に監視して、周波数の異常時に所定の安定化制
御を可能にする信頼性の高い電力系統安定化システムを
提供することにある。Another object of the present invention is to provide a highly reliable power system stabilizing system which monitors the system frequency at high speed and with high accuracy and enables predetermined stabilization control when the frequency is abnormal. is there.
【０００８】[0008]
【課題を解決するための手段】本発明の目的は、正弦波
の交流の周波数をリアルタイムに検出する周波数検出方
法において、交流の電圧または電流の瞬時量を所定の周
期でサンプリングし、サンプリング値の極性変化から零
点の存在を検知し、前記零点に対するサンプリングの位
相時間差を当該零点の直前及び直後のサンプリング値か
ら逆三角関数演算（ｔａｎ~1）により算出し、前回の零
点から今回の零点までの検出区間の時間を前記位相時間
差とこの間のサンプリング回数に基づいて算出し、前記
検出区間の時間の逆数より正弦波の交流の周波数を求め
ることにより達成される。SUMMARY OF THE INVENTION An object of the present invention is to provide a frequency detection method for detecting the AC frequency of a sine wave in real time by sampling the instantaneous amount of AC voltage or current at a predetermined cycle and The presence of a zero point is detected from the change in polarity, and the phase time difference of sampling with respect to the zero point is calculated by the inverse trigonometric function operation (tan to 1 ) from the sampling values immediately before and after the zero point, and from the previous zero point to the current zero point. This is achieved by calculating the time of the detection section based on the phase time difference and the number of times of sampling during this, and obtaining the AC frequency of the sine wave from the reciprocal of the time of the detection section.
【０００９】また、検出区間は、所定回（ｎ回）前の零
点から今回の零点までとし、この間の最初と最後の前記
位相時間差と前記サンプリング回数から前記検出区間の
時間を零点毎に算出し、該時間の逆数のｎ／２として正
弦波の交流の周波数を求めることにより達成される。Further, the detection section is set from a zero point before a predetermined number of times (n times) to the present zero point, and the time of the detection section is calculated for each zero point from the first and last phase time difference and the sampling number. , The reciprocal of the time, n / 2, to obtain the frequency of the sinusoidal alternating current.
【００１０】[0010]
【作用】図２を参照しながら本発明の原理を説明する。
交流入力波形のピーク値をｖｍ、サンプリング時刻Ｔ１
とＴ２間の零点からＴ２の位相角をθ1、一定サンプリ
ング周期△Ｔを電気角ｄで表現とすると、零点の直前、
直後のサンプリング値ｖ１、ｖ２は数式（１），（２）
より求まる。The principle of the present invention will be described with reference to FIG.
The peak value of the AC input waveform is vm, sampling time T1
If the phase angle of T2 from the zero point between T and T2 is represented by θ 1 and the constant sampling period ΔT is represented by the electrical angle d, immediately before the zero point,
Immediately after the sampling values v1 and v2 are expressed by the mathematical expressions (1) and (2)
Get more.
【００１１】[0011]
【数３】 ｖ１＝ｖｍ・ｓｉｎ（θ1−ｄ） ……（１） ｖ２＝ｖｍ・ｓｉｎθ1 ……（２） 式（１）を展開すると、式（３）となる。[Number 3] v1 = vm · sin (θ 1 -d) ...... (1) v2 = When you expand vm · sinθ 1 ...... (2) equation (1), the equation (3).
【００１２】[0012]
【数４】 ｖ１＝ｖｍ（ｓｉｎθ1・ｃｏｓｄ−ｃｏｓθ1・ｓｉｎｄ） ……（３） 数式（２）と（３）より、数式（４）と数式（５）が得
られる。Equation 4] v1 = vm (sinθ 1 · cosd -cosθ 1 · sind) ...... (3) and Equation (2) from (3), Equation (5) is obtained with Equation (4).
【００１３】[0013]
【数５】 ｖ２/ｓｉｎθ1＝ｖ１/(ｓｉｎθ1・ｃｏｓｄ−ｃｏｓθ1・ｓｉｎｄ)…（４） ｔａｎθ1＝ｖ２・ｓｉｎｄ／(ｖ２・ｃｏｓｄ−ｖ１) …（５） 式（５）において、ｖ１とｖ２の符号は常に反対となる
から、サンプリング角ｄが０〜９０度（通常はｄ＝３０
度）では、右辺の分母項が０となることがないので、い
わゆる不定処理の必要がない。また、右辺の演算結果は
常に０または正の値となる。[Number 5] v2 / sinθ 1 = v1 / ( sinθ 1 · cosd-cosθ 1 · sind) ... (4) tanθ 1 = v2 · sind / (v2 · cosd-v1) ... (5) In the formula (5), Since the signs of v1 and v2 are always opposite, the sampling angle d is 0 to 90 degrees (usually d = 30
), The denominator term on the right side does not become 0, so there is no need for so-called indefinite processing. The calculation result on the right side is always 0 or a positive value.
【００１４】この式（５）の逆正接として、位相角θ1
は数式（６）により求まる。As the arctangent of this equation (5), the phase angle θ 1
Can be obtained by equation (6).
【００１５】[0015]
【数６】 θ1＝ｔａｎ~1（ｖ２・ｓｉｎｄ／（ｖ２・ｃｏｓｄ−ｖ１）） …（６） サンプリング間隔△Ｔが定められると、その電気角ｄ及
びｓｉｎｄ，ｃｏｓｄは定数となる。[6] θ 1 = tan ~ 1 (v2 · sind / (v2 · cosd-v1)) ... (6) If the sampling interval △ T is determined, the electrical angle d and sind, cosd is a constant.
【００１６】位相角θ1は、零点に対するサンプリング
時刻Ｔ２の位相時間差△ｔ２の電気角表現であり、△ｔ
２は数式（７）により求まる。The phase angle θ 1 is an electrical angle expression of the phase time difference Δt2 at the sampling time T2 with respect to the zero point, and Δt
2 is obtained by the mathematical expression (7).
【００１７】[0017]
【数７】 △ｔ２＝（θ1／ｄ）・△ｔ＝（△Ｔ／ｄ）・ｔａｎ~1（ｖ２・ｓｉｎｄ ／（ｖ２・ｃｏｓｄ−ｖ１）） ……（７） 同様に、半サイクル後の零点直後の電気角をθ2とする
と、△ｔ６は数式（８）より求まる。[Formula 7] Δt2 = (θ 1 / d) · Δt = (ΔT / d) · tan ~ 1 (v2 · sind / (v2 · cosd-v1)) (7) Similarly, half cycle Assuming that the electrical angle immediately after the subsequent zero point is θ 2 , Δt6 can be obtained from the equation (8).
【００１８】[0018]
【数８】 △ｔ６＝（θ2／ｄ）・△ｔ＝（△Ｔ／ｄ）・ｔａｎ~1（ｖ６・ｓｉｎｄ ／（ｖ６・ｃｏｓｄ−ｖ５）） ……（８） よって、零点から零点までの半サイクルを周波数算出の
検出区間とすれば、毎回の検出区間の時間Ｔｓは数式
（９）、そのときの周波数ｆはＴｓの逆数の１／２とし
て、数式（１０）により求まる。[Formula 8] Δt6 = (θ 2 / d) · Δt = (ΔT / d) · tan to 1 (v6 · sind / (v6 · cosd−v5)) (8) Therefore, from the zero point to the zero point If the half cycle up to is the detection section for frequency calculation, the time Ts of each detection section is obtained by the equation (9), and the frequency f at that time is obtained by the equation (10) with 1/2 of the reciprocal of Ts.
【００１９】[0019]
【数９】 Ｔｓ＝△ｔ２＋４△Ｔ−△ｔ６ ……（９） ｆ＝１／（２Ｔｓ）＝１／（２（△ｔ２＋４△Ｔ−△ｔ６））……（１０） 数式（９）、（１０）を一般化すると、数式（１１）、
（１２）が得られる。Ts = Δt2 + 4ΔT−Δt6 (9) f = 1 / (2Ts) = 1 / (2 (Δt2 + 4ΔT−Δt6)) (10) Formula (9), Generalizing equation (10), equation (11)
(12) is obtained.
【００２０】[0020]
【数１０】 Ｔｓ＝△ｔ(1)i＋Ｋ・△Ｔ−△ｔi ……（１１） ｆ＝１／（２Ｔｓ）＝１／（２（△ｔ(1)i＋Ｋ・△Ｔ−△ｔi））…（１２） ここで、△ｔ(1)i：前回の零点との時間位相差、△
ｔi：今回の零点との時間位相差、Ｋ：前回の零点直後
の次のサンプリングから今回の零点直後までのサンプリ
ング回数である。[Equation 10] Ts = Δt (1) i + K · ΔT−Δt i (11) f = 1 / (2Ts) = 1 / (2 (Δt (1) i + K · ΔT−Δ t i )) ... (12) where Δt (1) i : time phase difference from the previous zero point, Δ
t i : time phase difference from the current zero point, K: number of samplings from the next sampling immediately after the previous zero point to immediately after the current zero point.
【００２１】本発明の周波数検出によれば、正弦波の交
流の半サイクルにおいて、零点前後の２のサンプリング
値を基に逆三角関数（ｔａｎ~1）により演算したサンプ
リング位相時間差を用いて、半サイクルの検出区間の実
時間をリアルタイムに算出し、この逆数より周波数を求
めているので、従来の直線近似に比べて検出精度を向上
できる。According to the frequency detection of the present invention, in the half cycle of the AC of the sine wave, the sampling phase time difference calculated by the inverse trigonometric function (tan ~ 1 ) based on the two sampling values before and after the zero point is used. Since the real time of the detection section of the cycle is calculated in real time and the frequency is obtained from this reciprocal, the detection accuracy can be improved as compared with the conventional linear approximation.
【００２２】また、周波数の演算には零点の直前、直後
の２のサンプリング値を用いるので、サンプリング周期
を通常用いられる３０度ていどにすれば、交流のピーク
値より十分に小さい値となり、Ａ／Ｄ変換時にスケール
オーバーして測定不能に陥ることがなく、信頼性の高い
周波数検出が可能になる。Further, since two sampling values immediately before and after the zero point are used for the frequency calculation, if the sampling period is set to 30 degrees which is normally used, the value becomes sufficiently smaller than the peak value of the alternating current. It is possible to detect a frequency with high reliability without causing scale-over at the time of D / D conversion to make measurement impossible.
【００２３】なお、上記における周波数の検出周期は、
零点毎の半サイクルとしているが、１サイクルにするこ
ともできる。即ち、サンプリング値の乗算による正負判
定が負の場合に、零点後のサンプリング値が正（または
負）となる零点のみを採用し、周波数演算を行う。The frequency detection cycle in the above is
Although it is set as a half cycle for each zero point, it may be set as one cycle. That is, when the positive / negative determination by multiplying the sampling value is negative, only the zero point where the sampling value after the zero point becomes positive (or negative) is adopted, and the frequency calculation is performed.
【００２４】さらに、本発明の拡張として、周波数算出
の検出区間を数式（１１）の半サイクルから任意倍数
（ｎ）半サイクルとし、且つ、周波数の検出周期は半サ
イクルとする方法が可能となる。この場合の検出区間の
時間Ｔｓと周波数ｆは、数式（１３）、（１４）により
求まる。Further, as an extension of the present invention, it is possible to adopt a method in which the detection interval of frequency calculation is changed from the half cycle of the equation (11) to an arbitrary multiple (n) half cycle, and the frequency detection period is half cycle. . The time Ts and the frequency f of the detection section in this case are obtained by the mathematical expressions (13) and (14).
【００２５】[0025]
【数１１】 Ｔｓ＝△ｔ(n)i＋Ｋn・△Ｔ−△ｔi ……（１３） ｆ＝ｎ／(２Ｔｓ)＝ｎ／（２（△ｔ(n)i＋Ｋn・△Ｔ−△ｔi））…（１４） ここで、△ｔ(n)i：ｎ倍半サイクル前の零点直後の位相
時間差、Ｋn：ｎ倍半サイクル前の零点直後の次から今
回零点直後までのサンプリング回数である。(11) Ts = Δt (n) i + K n · ΔT−Δt i (13) f = n / (2Ts) = n / (2 (Δt (n) i + K n · ΔT -Δt i )) ... (14) where Δt (n) i : Phase time difference immediately after the zero point before n times half cycle, K n : From the time immediately after the zero point before n times half cycle to the point immediately after this zero point Is the number of sampling times.
【００２６】これによれば、式（１４）の分母項におけ
るＫn・△Ｔは式（１２）のＫ・△Ｔの約ｎ倍となるの
で、分母項の位相時間差に含まれる誤差の影響がそのぶ
ん低下し、半サイクル毎の高速検出を維持しながら、周
波数の検出精度をさらに向上できる。According to this, since K n · ΔT in the denominator term of the equation (14) is about n times the K · ΔT of the equation (12), the influence of the error included in the phase time difference of the denominator term. However, the frequency detection accuracy can be further improved while maintaining high-speed detection every half cycle.
【００２７】これによれば、従来専用ハードによらなけ
れば困難であった周波数の変化幅の検出ができ、電力安
定化装置への適用が可能になる。According to this, it is possible to detect the range of change in frequency, which has been difficult with conventional dedicated hardware, and it is possible to apply to a power stabilizing device.
【００２８】[0028]
【実施例】本発明の実施例を図面を参照しながら説明す
る。Embodiments of the present invention will be described with reference to the drawings.
【００２９】図３は、本発明の一実施例による周波数検
出装置の構成を示したものである。電圧変成器４で計測
実測される電力系統３の電圧（電流でも可）は、高調波
成分を除去するフィルタ５、アナログ／デジタル変換す
るＡ／Ｄ変換器６を介して周波数検出装置１に取り込ま
れる。Ａ／Ｄ変換器６は周波数検出装置１から制御され
るサンプリング周期△Ｔ毎に、デジタル量のサンプリン
グ値を出力する。周波数検出装置１によって検出された
周波数は、表示手段などの出力装置７に出力される。な
お、フィルタ５やＡ／Ｄ変換器６を含めて、周波数検出
装置と呼んでもよい。FIG. 3 shows the configuration of a frequency detecting apparatus according to an embodiment of the present invention. The voltage (or current) of the power system 3 measured and measured by the voltage transformer 4 is taken into the frequency detection device 1 via the filter 5 for removing harmonic components and the A / D converter 6 for analog / digital conversion. Be done. The A / D converter 6 outputs a sampling value of a digital amount at every sampling period ΔT controlled by the frequency detecting device 1. The frequency detected by the frequency detection device 1 is output to the output device 7 such as display means. The filter 5 and the A / D converter 6 may be collectively referred to as a frequency detection device.
【００３０】周波数検出装置１は、処理の全体を制御す
る制御部１０、サンプリング値の取り込みや演算結果を
出力する入出力処理部１１及び周波数検出処理部１２を
具備している。記憶装置２は制御部１０によって書き込
み／読出しされ、演算に必要な範囲のサンプリング値の
時系列や、各部の演算結果などを格納する記憶エリアを
有している。The frequency detection device 1 comprises a control unit 10 for controlling the entire processing, an input / output processing unit 11 for taking in sampling values and outputting a calculation result, and a frequency detection processing unit 12. The storage device 2 has a storage area for storing the time series of the sampling values in the range necessary for calculation, the calculation result of each unit, and the like, which are written / read by the control unit 10.
【００３１】周波数検出処理部１２は、時系列のサンプ
リング値の符号変化から零点を検知する零点検出手段１
２１、周波数の検出区間のサンプリング回数をカウント
するサンプリング回数積算手段１２２、零点直後のサン
プリング点の位相差を逆三角関数により演算する位相差
演算手段１２３、位相差とサンプリング回数を用いて算
出した検出区間の時間から、系統の周波数を演算する周
波数演算手段１２４からなる。The frequency detection processing section 12 is a zero point detecting means 1 for detecting a zero point from a sign change of time-series sampling values.
21, sampling number integration means 122 that counts the number of times of sampling in the frequency detection section, phase difference calculation means 123 that calculates the phase difference of the sampling point immediately after the zero point by an inverse trigonometric function, and detection calculated using the phase difference and the number of times of sampling The frequency calculation means 124 calculates the frequency of the system from the time of the section.
【００３２】本例の周波数検出装置１はＣＰＵを利用
し、各部の機能を実行するプログラムやデータからなる
ソフトウエアで構成している。この場合、記憶装置２は
主メモリであり、これらプログラムやデータを記憶して
いる。The frequency detecting device 1 of this example uses a CPU and is composed of software including programs and data for executing the functions of the respective parts. In this case, the storage device 2 is the main memory and stores these programs and data.
【００３３】図１は、本実施例の周波数検出装置の動作
を説明するフローチャートで、被測定交流の半サイクル
を周波数算出の検出区間及び検出周期とした例である。
なお、サンプリング間隔ｄは、電力系統用保護リレーで
広く採用されている電気角３０度としている。FIG. 1 is a flow chart for explaining the operation of the frequency detecting apparatus of this embodiment, which is an example in which a half cycle of the alternating current to be measured is a detection section and a detection cycle for frequency calculation.
The sampling interval d is an electrical angle of 30 degrees which is widely adopted in protection relays for electric power systems.
【００３４】本処理は、サンプリングデータが入力され
る度に起動される。まず、今回のサンプリング値ｖiを
取り込んで記憶し（ｓ１０１）、サンプリング数Ｋを＋
１する（ｓ１０２）。なお、サンプリング数Ｋは、前回
の零点の検出時に０クリアされている。This process is started each time sampling data is input. First, the current sampling value v i is captured and stored (s101), and the sampling number K is set to +
1 (s102). The sampling number K is cleared to 0 at the previous detection of the zero point.
【００３５】次に、時系列に入力される前回のサンプリ
ング値ｖi-1と今回のサンプリング値ｖiを乗算する（ｓ
１０３）。の間の極性変化の有無を判定する。これはｖ
i-1とｖiを乗算し、乗算結果の正負を判定する（ｓ１０
４）。判定の結果が正であれば、両者のサンプリングの
間に極性（符号）の変化がない。即ち、前回と今回のサ
ンプリングの間に正弦波の交流の零点は存在しないの
で、処理を終了して次のサンプリングデータを待つ。Next, the previous sampling value v i-1 input in time series is multiplied by the current sampling value v i (s
103). Whether there is a change in polarity between This is v
i-1 and v i are multiplied to determine whether the multiplication result is positive or negative (s10
4). If the result of the determination is positive, there is no change in the polarity (sign) during the sampling of both. That is, since there is no AC zero point of the sine wave between the previous sampling and the current sampling, the processing is terminated and the next sampling data is waited for.
【００３６】一方、正負の判定結果が負であれば、前回
と今回の間に正弦波の交流の零点（ゼロクロス）が存在
するので、この零点と今回サンプリング点の位相時間差
△ｔiを数式（７）より求める（ｓ１０５）。On the other hand, if the positive / negative determination result is negative, there is a zero point (zero crossing) of the sine wave AC between the previous time and this time, so the phase time difference Δt i between this zero point and the current sampling point is expressed by the formula ( It is obtained from 7) (s105).
【００３７】本例はｄ＝３０度で、ｃｏｓｄ＝√３／
２，ｓｉｎｄ＝１／２となるので、数式（７）は数式
（１５）に置き替えられる。In this example, d = 30 degrees and cosd = √3 /
Since 2, sind = 1/2, Expression (7) is replaced with Expression (15).
【００３８】[0038]
【数１２】 △ｔi＝△Ｔ／３０・ｔａｎ~1(ｖi／(２√３・ｖi−４・ｖi-1)) …（１５） 今回の零点直後の位相時間差△ｔiは、次回の周波数演
算にも利用するために記憶される（ｓ１０６）。[Number 12] △ t i = △ T / 30 · tan ~ 1 (v i / (2√3 · v i -4 · v i-1)) ... (15) phase time difference immediately after the current zero point △ t i Are stored for use in the next frequency calculation (s106).
【００３９】なお、逆正接の変数部の値と△ｔiの対応
関係を、予めデータテーブル化して記憶装置２に格納し
ておけば、式（１５）の演算速度を上げることができ
る。If the correspondence between the value of the variable part of the arctangent and Δt i is made into a data table in advance and stored in the storage device 2, the calculation speed of the equation (15) can be increased.
【００４０】次に、数式（１１）に従い、前回の零点か
ら今回の零点までの時間、即ち検出区間の実時間を算出
し、その逆数を１／２して、半サイクルの検出区間にお
ける周波数を求める（ｓ１０７）。その後、Ｋを０クリ
アして（ｓ１０８）終了し、次のサンプリング待ちとな
る。Next, according to the equation (11), the time from the previous zero point to the current zero point, that is, the real time of the detection section is calculated, and the reciprocal thereof is halved to obtain the frequency in the detection section of the half cycle. Obtain (s107). After that, K is cleared to 0 (s108) and the process is terminated, and the next sampling is awaited.
【００４１】なお、周波数の検出周期を１サイクルとす
る場合は、上記のステップｓ１０２後に今回の入力デー
タｖiの正負判定を行い、正の場合のみステップｓ１０
３に移行し、負の場合は終了する。周波数は、検出区間
が１サイクルの実時間の逆数として計算されることはも
ちろんである。When the frequency detection period is set to one cycle, the positive / negative judgment of the current input data v i is performed after the above step s102, and if positive, step s10
Go to 3 and end if negative. It goes without saying that the frequency is calculated as the reciprocal of the real time of one cycle of the detection section.
【００４２】また、零点の直前のサンプリング点の位相
時間差△ｔi-1（＝△Ｔ−△ｔi）を算出し、前回の零点
直後の位相時間差と今回の零点直前の位相時間差とその
間のサンプリング回数から、検出区間の時間を求めるよ
うにしてもよい。さらには、零点の直後に代えて、零点
の直前のサンプリングの位相時間差△ｔi-1を基に、検
出区間の時間を算出することも可能である。Further, the phase time difference Δt i-1 (= ΔT−Δt i ) of the sampling point immediately before the zero point is calculated, and the phase time difference immediately after the previous zero point and the phase time difference immediately before the current zero point and between them are calculated. The time of the detection section may be obtained from the number of times of sampling. Furthermore, instead of immediately after the zero point, the time of the detection section can be calculated based on the phase time difference Δt i−1 of the sampling immediately before the zero point.
【００４３】本実施例によれば、半サイクルの短い検出
周期で、直線近似に比べ精度の高い周波数検出が可能で
ある。また、サンプリング周期ｄ＝３０度で、演算式の
分母項は０になることがないので、演算処理が簡単にな
る。しかも、演算に用いるサンプリング値は零点の直前
及び直後に限定されるので（他は符号のみを監視）、オ
ーバースケールによる測定不能を生じることもないの
で、信頼性が高い。According to the present embodiment, it is possible to detect a frequency with higher accuracy than a linear approximation with a short detection cycle of half a cycle. Further, since the denominator term of the arithmetic expression does not become 0 at the sampling cycle d = 30 degrees, the arithmetic processing becomes simple. Moreover, since the sampling value used for the calculation is limited to just before and after the zero point (others only monitor the sign), the measurement is not impossible due to overscale, so that the reliability is high.
【００４４】次に、本発明の第二の実施例を説明する。Next, a second embodiment of the present invention will be described.
【００４５】図４は、本実施例が適用される電力系統安
定化システムの概略の構成を示したものである。電力系
統は、点線内に模式的に示すように、複数の発電機４０
０から発電された電力を送電線３００を介して負荷に供
給する。発電機４００と送電線３００の接続を断／続す
る遮断器５００は、安定化装置１００の子局２００によ
って制御される。安定化装置１００は、通信線６００を
経由して電力系統の電圧や電流あるいは保護リレー等に
よる事故情報が取り込まれる。FIG. 4 shows a schematic configuration of a power system stabilizing system to which this embodiment is applied. The electric power system has a plurality of generators 40, as schematically shown in the dotted line.
The electric power generated from 0 is supplied to the load via the power transmission line 300. The circuit breaker 500 that disconnects / connects the generator 400 and the power transmission line 300 is controlled by the slave station 200 of the stabilizing device 100. The stabilizing device 100 receives the voltage and current of the electric power system or accident information by a protection relay or the like via the communication line 600.
【００４６】安定化装置１００は、周波数監視装置１０
０ａと図示していない電力系統の周波数整定値の設定手
段を具備し、周波数整定値に対する系統周波数が過大ま
たは過小となる場合に、子局２００に対して制御指令２
００ａを出力する。周波数監視装置１００ａは、安定化
装置１００が受信した電圧（または電流）をサンプリン
グ値（ｖｉ）として、系統の周波数を検出する。The stabilizing device 100 is the frequency monitoring device 10.
0a and a setting means for the frequency settling value of the power system (not shown) are provided, and when the system frequency for the frequency settling value is too large or too small, a control command 2 is issued to the slave station 200.
00a is output. The frequency monitoring device 100a detects the frequency of the grid by using the voltage (or current) received by the stabilizing device 100 as the sampling value (vi).
【００４７】子局２００は、制御指令２００ａに応じて
電力系統の遮断器５００の断／続や負荷制限あるいは系
統分離などの制御２００ｂを行い、脱調などの発生を防
止する。In response to the control command 200a, the slave station 200 performs control 200b such as disconnection / connection of the circuit breaker 500 of the power system, load limitation, or system separation to prevent occurrence of step-out.
【００４８】図５は、周波数監視装置１００ａの動作を
説明するフローチャートである。本例の周波数算出のた
めの検出区間はｎ倍の半サイクル、周波数の検出周期は
半サイクルである。通常、ｎは３〜５に設定される。FIG. 5 is a flow chart for explaining the operation of the frequency monitoring device 100a. The detection interval for frequency calculation in this example is n times the half cycle, and the frequency detection period is the half cycle. Usually, n is set to 3-5.
【００４９】周波数監視装置１００ａの処理動作は、周
波数整定値の変更要求が有る場合またはサンプリングデ
ータが入力される場合に起動される。変更要求の有る場
合は（ｓ２０１）、あらたな周波数整定値ｆ0を取り込
みまたは設定する（ｓ２０２）。なお、検出区間を設定
するための半サイクルの倍数ｎを変更する場合も、この
ステップで設定する。The processing operation of the frequency monitoring device 100a is activated when there is a request for changing the frequency set value or when sampling data is input. If there is a change request (s201), a new frequency settling value f 0 is fetched or set (s202). In addition, also when changing the multiple n of the half cycle for setting the detection section, it is set in this step.
【００５０】整定値変更要求が無いときは、今回のサン
プリング値ｖiを取り込んで記憶し（ｓ２０３）、前回
の零点以後のサンプリング数Ｋを＋１する（ｓ２０
４）。次に、前回のサンプリング値ｖi-1と今回のサン
プリング値ｖiを乗算し、その正負を判定し（ｓ２０
５）、判定が正の場合は終了する。When there is no set value change request, the current sampling value v i is fetched and stored (s203), and the sampling number K after the previous zero point is incremented by 1 (s20).
4). Next, the previous sampling value v i-1 is multiplied by the current sampling value v i to determine whether the sign is positive or negative (s20
5) If the determination is positive, the process ends.
【００５１】判定が負の場合は、前回と今回のサンプリ
ングの間に零点が存在するので、以下の処理を行う。If the determination is negative, there is a zero point between the previous sampling and the current sampling, so the following processing is performed.
【００５２】まず、ｎ回半サイクルの検出区間に亘っ
て、△Ｔ毎のサンプリング数Ｋnをカウントする（ｓ２
０６）。このＫnは半サイクル毎の積算値の積み重ねと
して、下記の式順（矢印）で算出される。First, the sampling number K n for each ΔT is counted over the detection section of n times and half cycles (s2
06). This K n is calculated in the following formula order (arrow) as a stack of integrated values for each half cycle.
【００５３】[0053]
【数１３】Ｋn＝Ｋn-1＋Ｋ ↓ Ｋn-1＝Ｋn-2＋Ｋ ↓ ・・・・・・・・ ↓ Ｋ2＝Ｋ1＋Ｋ ↓ Ｋ1＝Ｋ すなわち、前回の（ｎ−１）半サイクル前〜半サイクル
前までの積算値Ｋn-1，Ｋn-2，．．．．Ｋ2，Ｋ1の各々
に、今回の半サイクルのＫを順次加算し、１歩進された
今回のｎ半サイクル前〜１サイクル前までの積算値（Ｋ
n，．．．Ｋ2）を算出する。今回の半サイクル前の積算
値Ｋ1＝Ｋとなる。[Formula 13] K n = K n-1 + K ↓ K n-1 = K n-2 + K ↓ ・ ・ ・ ・ ・ ・ ↓ K 2 = K 1 + K ↓ K 1 = K That is, the previous (n -1) Integrated values Kn-1 , Kn-2 ,. ． ． ． K of the current half cycle is sequentially added to each of K 2 and K 1 , and the integrated value (K of the previous n half cycles to 1 cycle before is incremented by 1 step
n ,. ． ． Calculate K 2 ). The integrated value K 1 = K before the current half cycle.
【００５４】次に、数式（１５）より今回のサンプリン
グの位相時間差△ｔiを算出し（ｓ２０７）、記憶する
（ｓ２０８）。さらにｎ回前の零点から今回の零点まで
の検出区間の時間Ｔｓを数式（１３）、周波数ｆを数式
（１４）より求める（ｓ２０９）。この後、Ｋを０クリ
アする（ｓ２１０）。Next, the phase time difference Δt i of the current sampling is calculated from the equation (15) (s207) and stored (s208). Further, the time Ts of the detection section from the zero point n times before to the current zero point is calculated by the mathematical expression (13) and the frequency f is calculated by the mathematical expression (14) (s209). After this, K is cleared to 0 (s210).
【００５５】次に、周波数整定値ｆ0に対する検出周波
数ｆの偏差△ｆを求め、偏差△ｆが許容範囲内にあるか
判定し（ｓ２１１）、許容範囲内にあれば正常とみて検
出周波数のみを出力し（ｓ２１３）、表示または記録さ
れる。Next, the deviation Δf of the detection frequency f with respect to the frequency set value f 0 is obtained, and it is judged whether the deviation Δf is within the allowable range (s211). If it is within the allowable range, it is considered normal and only the detected frequency is detected. Is output (s213) and displayed or recorded.
【００５６】いっぽう、検出周波数が整定値以上であれ
ば、負荷電力量に比べて発電量が大きく、整定値以下で
あれば発電量が少ない。いずれの場合にも、許容範囲を
超える異常周波数となれば系統に脱調を生じるので、電
力系統の発電量制限または負荷制限あるいは系統分離な
どの安定化制御を行う必要がある。On the other hand, if the detected frequency is above the set value, the amount of power generation is greater than the load power amount, and if it is below the set value, the amount of power generation is small. In either case, if the abnormal frequency exceeds the allowable range, the system may be out of step, so it is necessary to perform stabilization control such as power generation amount restriction or load restriction or system separation of the power system.
【００５７】そこで、検出周波数の整定値の許容範囲を
超えている場合は、周波数の異常信号を安定化装置１０
０に出力する（ｓ２１２）。Therefore, if the detected frequency exceeds the allowable range of the settling value, an abnormal signal of the frequency is stabilized by the stabilizing device 10.
It is output to 0 (s212).
【００５８】本実施例によれば、ｎ倍の半サイクルに延
長された検出区間によって、系統の周波数が高精度に且
つ半サイクル毎に検出できる。ちなみに、本実施例によ
る周波数の検出誤差は、周波数５％の変動時で、従来の
０．０６％から０．００９％と、１桁ちかく改善されて
いる。According to the present embodiment, the frequency of the system can be detected with high accuracy and every half cycle by the detection section extended to n times the half cycle. By the way, the frequency detection error according to the present embodiment is improved by one digit from 0.06% in the conventional case to 0.009% when the frequency changes by 5%.
【００５９】この結果、系統周波数の整定値変更などの
場合にも、周波数変化幅の検出が高速且つ高精度に実現
できるので、電力系統安定化システムの信頼性を一段と
向上できる。As a result, even when the set value of the system frequency is changed, the frequency change width can be detected at high speed and with high accuracy, so that the reliability of the power system stabilizing system can be further improved.
【００６０】上記の実施例で、周波数監視装置１００ａ
は安定化装置１００に付設したが、子局２００に付設し
て、同様な監視を行わせることも可能である。In the above embodiment, the frequency monitoring device 100a.
Is attached to the stabilization device 100, but it is also possible to attach it to the slave station 200 and perform similar monitoring.
【００６１】[0061]
【発明の効果】本発明の周波数検出方法によれば、交流
の零点前後のサンプリング値を元に、零点とサンプリン
グ周期の位相差を逆三角関数により演算し、これより零
点から零点までの検出区間の時間を算出するので、検出
精度を向上できる効果がある。しかも、半サイクルの検
出周期を維持しながら、任意倍数の半サイクルに検出区
間を延長することが可能で、より精度を向上できる効果
がある。According to the frequency detecting method of the present invention, the phase difference between the zero point and the sampling period is calculated by the inverse trigonometric function based on the sampling values before and after the zero point of the alternating current, and from this, the detection section from the zero point to the zero point. Since the time is calculated, there is an effect that the detection accuracy can be improved. Moreover, it is possible to extend the detection section to half cycles of an arbitrary multiple while maintaining the detection cycle of half cycle, and there is an effect that the accuracy can be further improved.
【００６２】本発明の周波数検出装置によれば、ソフト
機能によって専用のハードと同等以上のものを安上がり
に実現でき、かつ、零点近傍のサンプリング値を利用す
る検出原理から測定不能を生じることがなく、信頼性を
向上できる効果がある。According to the frequency detecting apparatus of the present invention, the software function enables the realization of a hardware equivalent to or more than the dedicated hardware at a low cost, and the measurement principle using the sampling value near the zero point does not cause measurement failure. There is an effect that the reliability can be improved.
【００６３】本発明の電力系統安定化システムによれ
ば、半サイクル毎に系統周波数を高精度に検出して整定
値に対する変化幅を監視し、系統周波数の過大または過
小を正確に評価して所定の安定化制御を実行するので、
電力系統における脱調などを防止でき、システムの信頼
性を一段と向上できる効果がある。According to the power system stabilizing system of the present invention, the system frequency is detected with high accuracy every half cycle, and the variation width with respect to the settling value is monitored to accurately evaluate whether the system frequency is too large or too small. Since the stabilization control of is executed,
It is possible to prevent out-of-steps in the power system and to further improve the system reliability.
【図１】本発明の一実施例の周波数検出方法を説明する
フローチャート。FIG. 1 is a flowchart illustrating a frequency detection method according to an embodiment of the present invention.
【図２】被測定交流の波形とサンプリング時間の関係を
説明する説明図。FIG. 2 is an explanatory diagram illustrating a relationship between a waveform of an alternating current to be measured and a sampling time.
【図３】本発明の一実施例の周波数検出装置を説明する
構成図。FIG. 3 is a configuration diagram illustrating a frequency detection device according to an embodiment of the present invention.
【図４】電力系統安定化システムの概略を説明する構成
図。FIG. 4 is a configuration diagram illustrating an outline of a power system stabilizing system.
【図５】第二の実施例の周波数監視方法を説明するフロ
ーチャート。FIG. 5 is a flowchart illustrating a frequency monitoring method according to a second embodiment.
１…周波数検出装置（ＣＰＵ）、２…記憶装置（主メモ
リ）、３…電力系統、４…電圧変成器、５…フィルタ、
６…Ａ／Ｄ変換器、７…出力装置、１０…制御部、１１
…入出力処理部、１２…周波数検出処理部、１００…電
力系統安定化装置、１００ａ…周波数監視装置、１２１
…零点検出手段、１２２…サンプリング回数積算手段、
１２３…位相差演算手段、１２４…周波数演算手段、△
Ｔ…サンプリング周期、ｄ…サンプリング周期の電気角
表現、ｖｉ…サンプリング値、θｉ…零点から直後のサ
ンプリング点までの位相角、△ｔｉ…零点から直後のサ
ンプリング点までの位相時間差、Ｔｓ…検出区間の時
間、ｆ…検出周波数。1 ... Frequency detection device (CPU), 2 ... Storage device (main memory), 3 ... Power system, 4 ... Voltage transformer, 5 ... Filter,
6 ... A / D converter, 7 ... Output device, 10 ... Control part, 11
Input / output processing unit 12, frequency detection processing unit 100, power system stabilizing device 100a, frequency monitoring device 121
... Zero point detecting means, 122 ... Sampling number integrating means,
123 ... Phase difference calculating means, 124 ... Frequency calculating means, Δ
T ... Sampling cycle, d ... Electrical angle expression of sampling cycle, vi ... Sampling value, θi ... Phase angle from zero point to the next sampling point, Δti ... Phase time difference from zero point to the next sampling point, Ts ... Detection section Time, f ... Detection frequency.
Claims (10)
検出する周波数検出方法において、 交流の電圧または電流の瞬時量を所定の周期でサンプリ
ングし、サンプリング値の極性変化から零点の存在を検
知し、前記零点に対するサンプリングの位相時間差を当
該零点の直前及び直後のサンプリング値から逆三角関数
演算（ｔａｎ~1）により算出し、前回の零点から今回の
零点までの検出区間の時間を前記位相時間差とこの間の
サンプリング回数に基づいて算出し、前記検出区間の時
間の逆数より正弦波の交流の周波数を求めることを特徴
とする周波数検出方法。1. A frequency detecting method for detecting the AC frequency of a sine wave in real time, wherein the instantaneous amount of AC voltage or current is sampled at a predetermined cycle, and the presence of a zero point is detected from the polarity change of the sampled value. The sampling phase time difference with respect to the zero point is calculated from the sampling values immediately before and after the zero point by the inverse trigonometric function operation (tan ~ 1 ), and the time of the detection section from the previous zero point to the current zero point is calculated as the phase time difference and The frequency detection method is characterized in that the frequency of the sinusoidal wave is calculated from the reciprocal of the time of the detection section.
後のサンプリングの位相時間差△ｔであり、（数１）に
より算出されることを特徴とする周波数検出方法。 【数１】△ｔ＝（△Ｔ／ｄ）・ｔａｎ~1（ｖ２・ｓｉｎｄ
／(ｖ２・ｃｏｓｄ−ｖ１)） ここで、△Ｔはサンプリング周期、ｄは△Ｔの電気角、
ｖ１は零点直前のサンプリング値、ｖ２は零点直後のサ
ンプリング値である。2. The frequency detection method according to claim 1, wherein the sampling phase time difference is a sampling phase time difference Δt immediately after the zero point, and is calculated by (Equation 1). [Formula 1] Δt = (ΔT / d) · tan ~ 1 (v2 · sind
/ (V2 · cosd-v1)) where ΔT is the sampling period, d is the electrical angle of ΔT,
v1 is a sampling value immediately before the zero point, and v2 is a sampling value immediately after the zero point.
記検出区間の時間Ｔｓは（数２）により算出され、Ｔｓ
の逆数の１／２として周波数を求めることを特徴とする
周波数検出方法。 【数２】Ｔｓ＝△ｔｉ(1)＋Ｋ△Ｔ−△ｔｉ ここで、△ｔｉ(1)は前回の位相時間差、△ｔｉは今回
の位相時間差、Ｋは前記サンプリング回数である。3. The method according to claim 2, wherein the previous zero point is before a half cycle of sinusoidal wave alternating current, and the time Ts of the detection section is calculated by (Equation 2).
A frequency detecting method, characterized in that the frequency is obtained as 1/2 of the reciprocal of. ## EQU2 ## Ts = Δti (1) + KΔT−Δti where Δti (1) is the previous phase time difference, Δti is the current phase time difference, and K is the number of times of sampling.
る周波数検出方法。4. The frequency detection method according to claim 1, 2 or 3, wherein the frequency is detected every half cycle.
前記零点直後のサンプリング値が正または負となる場合
のみを採用し、前回の零点が正弦波交流の１サイクル前
となる前記検出区間の時間の逆数として、１サイクル毎
に周波数を求めることを特徴とする周波数検出方法。5. The zero point according to claim 1 or 2,
Only when the sampling value immediately after the zero point is positive or negative is adopted, and the frequency is obtained for each cycle as the reciprocal of the time of the detection section in which the previous zero point is one cycle before the sinusoidal wave AC. Frequency detection method.
検出する周波数検出方法において、 交流の瞬時量を所定の周期でサンプリングし、サンプリ
ング値の極性変化から零点の存在を検知し、その零点の
直前及び直後のサンプリング値から前記サンプリングの
位相時間差を逆三角関数演算（ｔａｎ~1）により算出
し、所定回数（以下、ｎ回と呼ぶ）前の半サイクルの零
点に対応する位相時間差と今回の零点に対応する位相時
間差及びｎ回前の零点から今回の零点までの検出区間の
サンプリング回数に基づいて前記検出区間の時間を算出
し、該時間の逆数のｎ／２として正弦波の交流の周波数
を求めることを特徴とする周波数検出方法。6. A frequency detecting method for detecting an AC frequency of a sine wave every half cycle, sampling an instantaneous amount of AC at a predetermined cycle, detecting the presence of a zero point from the polarity change of the sampling value, and detecting the zero point. The phase time difference of the sampling is calculated from the sampling values immediately before and immediately after by the inverse trigonometric function operation (tan to 1 ), and the phase time difference corresponding to the zero point of the half cycle before a predetermined number of times (hereinafter, referred to as n times) and this time. Of the sine wave as the reciprocal of n / 2, which is the reciprocal of the time, based on the phase time difference corresponding to the zero point and the number of times of sampling of the detection section from the zero point before n times to the present zero point. A frequency detection method characterized by obtaining a frequency.
に設定されることを特徴とする周波数検出方法。7. The frequency detecting method according to claim 1, wherein the predetermined cycle of the sampling is set to 30 degrees in electrical angle expression.
検出する周波数検出装置において、 交流の電圧または電流の瞬時量を所定の周期でサンプリ
ングするサンプリング手段と、 時系列に入力されるサンプリング値の極性変化から零点
の存在を検知する零点検知手段と、 前記零点に対するサンプリングの位相時間差を当該零点
の直前及び直後のサンプリング値から逆三角関数演算
（ｔａｎ~1）により算出する位相差演算手段と、 所定回（以下、ｎ回）前の零点から今回の零点までの検
出区間におけるサンプリング回数をカウントするサンプ
リング回数積算手段と、 ｎ回前の零点に対応する位相時間差と今回の零点に対応
する位相時間差及び前記サンプリング回数に基づいて前
記検出区間の時間を算出し、該時間の逆数から正弦波の
交流の周波数を算出する周波数演算手段と、 ｎ回前から今回までの前記位相時間差を記憶する記憶手
段と、を備えることを特徴とする周波数検出装置。8. A frequency detecting device for detecting a sinusoidal AC frequency in real time, comprising: sampling means for sampling an instantaneous amount of AC voltage or current in a predetermined cycle; and polarity of a sampling value input in time series. A zero point detecting means for detecting the presence of a zero point from the change; a phase difference calculating means for calculating a sampling phase time difference with respect to the zero point from the sampling values immediately before and after the zero point by an inverse trigonometric function operation (tan to 1 ); Sampling number integration means for counting the number of sampling times in the detection section from the zero point before (hereinafter, n times) to the present zero point, the phase time difference corresponding to the zero point before n times and the phase time difference corresponding to the current zero point, and The time of the detection section is calculated based on the number of times of sampling, and the reciprocal of the time is used to calculate the AC frequency of the sine wave. A frequency detecting device comprising: a frequency calculating means for calculating a wave number; and a storage means for storing the phase time difference from n times before to this time.
ジタル量に変換するＡ／Ｄ変換器を有し、前記所定の周
期を電気角表現で３０度に設定されてなることを特徴と
する周波数検出装置。9. The sampling means according to claim 8, further comprising an A / D converter that converts the instantaneous amount of analog amount into a digital amount, and the predetermined period is set to 30 degrees in electrical angle expression. A frequency detection device characterized by the following.
供給する送電線から構成される電力系統の周波数の異常
時に、電源や系統構成の制御を行う電力系統安定化シス
テムにおいて、 電力系統の交流量を電気角３０度の周期でサンプリング
し、交流の零点の直前及び直後のサンプリング値から前
記サンプリングの位相時間差を逆三角関数演算（ｔａｎ
~1）により算出し、所定回数前の半サイクルの零点から
今回の零点までの検出区間の時間を前記位相時間差とサ
ンプリング回数を基に算出して電力系統の周波数を求め
る周波数検出手段と、 電力系統の周波数制定値に対する前記周波数検出手段に
よる周波数の偏差を求め、所定の範囲を超えているとき
に異常信号を出力する周波数変化幅監視手段と、を設け
ることを特徴とする電力系統安定化システム。10. A power system stabilizing system that controls a power supply and a system configuration when a frequency of a power system including a load, a plurality of generators, and a power transmission line that supplies power to the load is abnormal. Is sampled at a cycle of an electrical angle of 30 degrees, and the phase time difference of the sampling is calculated by an inverse trigonometric function (tan) from the sampling values immediately before and after the zero point of the AC.
~ 1 ) to calculate the time of the detection section from the zero point of the half cycle before the predetermined number of times to the zero point of this time based on the phase time difference and the number of sampling times, and the frequency detection means for obtaining the frequency of the power system, A power system stabilization system comprising: a frequency variation width monitoring unit that obtains a deviation of the frequency detected by the frequency detection unit with respect to a frequency set value of the system and outputs an abnormal signal when the frequency exceeds a predetermined range. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13558694A JP3220327B2 (en) | 1994-06-17 | 1994-06-17 | Frequency detection method and apparatus, and power system stabilization system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13558694A JP3220327B2 (en) | 1994-06-17 | 1994-06-17 | Frequency detection method and apparatus, and power system stabilization system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH085679A true JPH085679A (en) | 1996-01-12 |
| JP3220327B2 JP3220327B2 (en) | 2001-10-22 |
Family
ID=15155293
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13558694A Expired - Fee Related JP3220327B2 (en) | 1994-06-17 | 1994-06-17 | Frequency detection method and apparatus, and power system stabilization system |
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