JP4331006B2 - GAIN ADJUSTMENT METHOD FOR BANDPASS FILTER AND SYNCHRONOUS RECTIFICATION CIRCUIT built in DC circuit ground fault detection device and DC circuit ground fault detection device - Google Patents
GAIN ADJUSTMENT METHOD FOR BANDPASS FILTER AND SYNCHRONOUS RECTIFICATION CIRCUIT built in DC circuit ground fault detection device and DC circuit ground fault detection device Download PDFInfo
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変電所，発電所や大規模プラントにおいては機器の制御のために直流回路が用いられる。通常直流回路にはＪＥＭ１０９０（日本電機工業会規格１０９０）で定められた直流地絡過電圧継電器６４Ｄ（直流地絡継電器６４Ｄという）が接続されている。本発明のバンドパスフィルタ・同期整流回路の調整方法は，直流地絡が発生したときに，直流地絡継電器６４Ｄに代わって直流回路に接続され，直流回路のN極とアース間に交流信号を生成させ，その交流信号から地絡抵抗に流れる漏れ電流を，変流器ＺＣＴによって検出する直流電路地絡検出装置に内蔵するバンドパスフィルタ・同期整流回路のゲイン調整技術に関する。 In substations, power plants and large-scale plants, DC circuits are used to control equipment. A normal DC circuit is connected to a DC ground fault overvoltage relay 64D (referred to as a DC ground fault relay 64D) defined by JEM1090 (Japan Electrical Manufacturers Association Standard 1090). The adjustment method of the bandpass filter / synchronous rectifier circuit of the present invention is connected to a DC circuit instead of the DC ground fault relay 64D when a DC ground fault occurs, and an AC signal is connected between the N pole of the DC circuit and the ground. The present invention relates to a gain adjustment technique for a band-pass filter / synchronous rectifier circuit built in a DC circuit ground fault detection device that generates and detects a leakage current flowing from the AC signal to a ground fault resistance by a current transformer ZCT.
バンドパスフィルタ部や同期整流回路部には抵抗やコンデンサが使用されているが，これらの部品は誤差範囲を含んでいる。コスト面と特性面の兼ね合いで，実際に使用する部品は抵抗で±1％程度，コンデンサで±10％程度の誤差を有している。回路を構成するこれら部品の誤差が累積するため，測定には必ず増幅度（ゲインという）の調整が必要である（非特許文献１参照）。 Resistors and capacitors are used in the bandpass filter unit and the synchronous rectifier circuit unit, but these components include an error range. Due to the balance between cost and characteristics, the parts actually used have an error of about ± 1% for the resistance and ± 10% for the capacitor. Since errors of these components constituting the circuit are accumulated, adjustment of the degree of amplification (referred to as gain) is always required for measurement (see Non-Patent Document 1).
従来はバンドパスフィルタ部や同期整流回路部にそれぞれ半固定抵抗を設けておき，測定入力に基準値を入力したときの出力を測定器で測定したとき調整値になるよう，人手により半固定抵抗を調整する必要があった。
図３は従来，バンドパスフィルタ部や同期整流回路部に設けていたゲイン調整回路の例である。予め定められた校正用の信号入力により，入力された信号に対する出力を測定器で測定し，出力が該予め定められた校正用の信号入力に相応する期待値になるよう，半固定抵抗ＶＲ１を手動で回しながらゲイン調整を行っていた。
Conventionally, a semi-fixed resistor is provided for each of the bandpass filter unit and the synchronous rectifier circuit unit, and the semi-fixed resistor is manually adjusted so that the output when the reference value is input to the measurement input becomes the adjustment value when measured with a measuring instrument. There was a need to adjust.
FIG. 3 shows an example of a gain adjustment circuit conventionally provided in a band-pass filter unit or a synchronous rectification circuit unit. With a predetermined calibration signal input, the output for the input signal is measured by a measuring instrument, and a semi-fixed resistor VR1 is set so that the output becomes an expected value corresponding to the predetermined calibration signal input. The gain was adjusted while turning manually.
しかしながら，従来の方法では半固定回路の調整を人手で行っていたため作業の得手不得手による調整のばらつきが生じたり，調整に時間がかかり，生産コストが上昇するという問題があった。時間の内訳は，試験条件の設定時間，測定器の準備・接続時間，半固定抵抗を回して調整する時間などである。人手による工程上の調整に要する時間は，半日〜一日程かかっていた。また調整回路における半固定抵抗は高価であるため装置のコストアップになるという課題があった。また，コンデンサや抵抗などの部品は経年変化により，その容量や抵抗値が変化するため，工場出荷時に合わせたゲイン調整値から徐々にずれる。そのため長期的にメンテナンス作業が必要になり，技術者が設置場所へ赴き，先に述べたようなゲイン調整を行う必要性が生じ，後々のメンテナンス費用が発生するなどコストがアップするという問題があった。 However, in the conventional method, since the semi-fixed circuit is manually adjusted, there is a problem in that the adjustment varies due to the poorness of the work, the adjustment takes time, and the production cost increases. The breakdown of time includes test condition setting time, measuring instrument preparation and connection time, and adjustment time by turning a semi-fixed resistor. It took half a day to a day to adjust the process manually. Further, since the semi-fixed resistor in the adjustment circuit is expensive, there is a problem that the cost of the apparatus is increased. In addition, since the capacitance and resistance values of components such as capacitors and resistors change over time, they gradually deviate from the gain adjustment values adjusted at the time of factory shipment. As a result, maintenance work is required for a long period of time, and it is necessary for the engineer to go to the installation site and perform gain adjustment as described above. It was.
そこで本件の発明の目的とするところは，ゲイン調整を自動で行うことにより，人手によるゲイン調整時間を不要とし，製造工程及びメンテナンス時のゲイン調整におけるコストを削減できるとともに，高価な半固定抵抗を削除してコストの上昇を抑えることが可能なバンドパスフィルタ・同期整流回路の調整方法を提供することである。 Therefore, the object of the present invention is to perform gain adjustment automatically, thereby eliminating the need for manual gain adjustment time, reducing the cost of gain adjustment during the manufacturing process and maintenance, and adding expensive semi-fixed resistors. An object of the present invention is to provide a method for adjusting a band-pass filter / synchronous rectifier circuit that can be eliminated to suppress an increase in cost.
上述の目的を達成するために，本発明では，直流地絡が発生したときに，直流地絡継電器６４Ｄに代わって直流回路に接続され，直流回路のN極とアース間に交流信号を生成させ，その交流信号から地絡抵抗に流れる漏れ電流を，
直流電路に接続された零相変流器ＺＣＴによって検出する直流電路地絡検出装置において，該直流電路地絡検出装置に内蔵されたバンドパスフィルタ・同期整流回路を校正モードと測定モードとに切替えるモード切替手段を備え，
校正モードにおいては，校正用矩形波発生回路から，直流電路地絡検出装置内部でＺＣＴを介さずに前記バンドパスフィルタに校正用矩形波ａを入力され，該バンドパスフィルタを通過して得られる正弦波ａ１は，同期整流回路と波形成形回路とに入力され，該波形成形回路を通過して得られる矩形波ａ２によって同期整流回路は同期整流を行い，同期整流した出力をＡＤ変換部にてＡＤ変換して値Ｘを得，該値Ｘ
と，校正用矩形波ａに対する出力の期待値Ｗからバンドパスフィルタの増幅度（ゲイン） を表す定数Ｗ／Ｘを演算部により演算し，
測定モードにおいては，前記バンドパスフィルタに測定入力端子から測定入力ｂが入力され，該バンドパスフィルタを通過して得られる正弦波ｂ１は前記同期整流回路に入力されるとともに，同期整流回路は，同期整流基準矩形波発生回路から発生される基準矩形波ｃによって同期整流を行い，同期整流した出力をＡＤ変換部にてＡＤ変換して値Ｙを得，
該値Ｙと前記定数Ｗ／Ｘを用いて，
測定結果の値Ａ＝Ｙ×Ｗ／Ｘを演算部により演算することにより，測定結果の値を得ることを特徴として直流電路地絡検出装置に内蔵されたバンドパスフィルタ・同期整流回路のゲイン調整方法を提供したものである。
In order to achieve the above object, in the present invention, when a DC ground fault occurs, the DC circuit is connected to the DC circuit instead of the DC ground fault relay 64D, and an AC signal is generated between the N pole and the ground of the DC circuit. , The leakage current that flows from the AC signal to the grounding resistance,
In a DC circuit ground fault detection device that detects by a zero-phase current transformer ZCT connected to the DC circuit, a mode switch that switches the band-pass filter / synchronous rectifier circuit built in the DC circuit ground fault detection device between a calibration mode and a measurement mode. With means,
In the calibration mode, the calibration rectangular wave a is input from the calibration rectangular wave generation circuit to the bandpass filter without passing through the ZCT inside the DC circuit ground fault detection device , and is obtained by passing through the bandpass filter. The wave a1 is input to the synchronous rectification circuit and the waveform shaping circuit, and the synchronous rectification circuit performs synchronous rectification by the rectangular wave a2 obtained by passing through the waveform shaping circuit. Convert to get value X, which
And a constant W / X representing the amplification degree (gain) of the bandpass filter from the expected value W of the output with respect to the calibration rectangular wave a, and
In the measurement mode, the measurement input b is input from the measurement input terminal to the bandpass filter, the sine wave b1 obtained by passing through the bandpass filter is input to the synchronous rectifier circuit, Synchronous rectification is performed by the reference rectangular wave c generated from the synchronous rectification reference rectangular wave generation circuit, and the value Y is obtained by performing AD conversion on the synchronously rectified output by the AD conversion unit,
Using the value Y and the constant W / X,
A gain adjustment method for a band-pass filter / synchronous rectifier circuit built in a DC circuit ground fault detector , characterized in that a measurement result value is obtained by calculating a measurement result value A = Y × W / X by a calculation unit. Is provided.
また，前記直流電路地絡検出装置において，
常には校正モードで動作され，電路に接続された直流地絡過電圧継電器６４Ｄからの起動信号を起動信号受信部にて受信した場合には，モード切替手段により測定モードに切替り，該測定モードにて動作することを特徴として請求項１記載のゲイン調整方法を用いた直流電路地絡検出装置を提供したものである。
Further, in the direct current alley fault detector,
When the activation signal receiving unit receives the activation signal from the DC ground fault overvoltage relay 64D connected to the electric circuit, the operation mode is switched to the measurement mode by the mode switching means. The present invention provides a DC circuit ground fault detection device using the gain adjustment method according to claim 1.
以上のように本件の発明によれば，ゲイン調整を自動で行うことにより，人手によるゲイン調整時間を不要とし，製造工程及びメンテナンス時のゲイン調整におけるコストを削減できるとともに，高価な半固定抵抗を削除してコストの上昇を抑えることが可能なバンドパスフィルタ・同期整流回路のゲイン調整方法及び該ゲイン調整方法を用いた直流電路地絡検出装置を提供することができる。 As described above, according to the present invention, the gain adjustment is automatically performed, thereby eliminating the need for manual gain adjustment time, reducing the cost of gain adjustment during the manufacturing process and maintenance, and providing an expensive semi-fixed resistor. It is possible to provide a bandpass filter / synchronous rectifier circuit gain adjustment method that can be eliminated to suppress an increase in cost, and a DC circuit ground fault detection device using the gain adjustment method.
以下，本発明の実施の形態について，図面を用いて詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
図１は本件発明のバンドパスフィルタ・同期整流回路の自動ゲイン調整回路の実施例を示したものである。 FIG. 1 shows an embodiment of an automatic gain adjustment circuit of a band-pass filter / synchronous rectifier circuit according to the present invention.
１は校正用矩形波を発生させる校正用矩形波発生回路，２は測定時において測定入力を入力される測定入力端子，３はバンドパスフィルタ，４は同期整流回路である。３と４でバンドパスフィルタ・同期整流回路を構成する。 Reference numeral 1 is a calibration rectangular wave generating circuit for generating a calibration rectangular wave, 2 is a measurement input terminal for inputting a measurement input during measurement, 3 is a band-pass filter, and 4 is a synchronous rectifier circuit. 3 and 4 constitute a band-pass filter / synchronous rectifier circuit.
同期整流回路は，同期整流用矩形波の論理にに基づき（特開平８−１８２１７９号を参照願いたい），直流電路において全漏れ電流から抵抗成分（Ｒ分）の漏れ電流を分離するときに用いられるものである。電路に低周波の電圧を生成させ，地絡電流のうち，対地静電容量成分（Ｃ分という）と抵抗成分（Ｒ分という）とで位相が９０度ずれていることを利用して，同期整流用矩形波の変化点に基づき，Ｃ分の漏れ電流をキャンセルしＲ分の電流を分離する。 The synchronous rectifier circuit is based on the logic of the rectangular wave for synchronous rectification (see Japanese Patent Laid-Open No. 8-182179) and is used to separate the leakage current of the resistance component (R component) from the total leakage current in the DC circuit. It is A low-frequency voltage is generated in the electric circuit, and the ground fault current is synchronized by utilizing the fact that the phase of the ground capacitance component (referred to as C component) and the resistance component (referred as R component) are shifted by 90 degrees. Based on the change point of the rectifying rectangular wave, the leakage current for C is canceled and the current for R is separated.
５は波形成形回路であり，バンドパスフィルタから出力される正弦波が通過することにより，該正弦波のゼロクロス点でＨｉｇｈ−Ｌｏｗ状態が順次切り変わる矩形波を出力する。 Reference numeral 5 denotes a waveform shaping circuit, which outputs a rectangular wave whose High-Low state is sequentially switched at the zero cross point of the sine wave when the sine wave output from the band pass filter passes.
６は同期整流基準矩形波の発生回路であり，先に述べた，電路に生成される低周波の電圧を，同期整流の基準となるよう，測定電路を介さない場所に設けられた変流器にて検知し，出力された信号を用いて，同期整流を行う際に用いられる基準矩形波を発生させる。 6 is a circuit for generating a synchronous rectification reference rectangular wave, and the current transformer provided in a place not passing through the measurement circuit so that the low-frequency voltage generated in the circuit can be used as a reference for synchronous rectification. The reference rectangular wave used when performing synchronous rectification is generated using the signal detected and output by.
７０はＡＤ変換部（ＡＤＣという）でありアナログデータをディジタルデータに変換する。７１は演算部でありＡＤＣ７０から出力された信号を元に演算を行うものである。これら７０，７１は，同期整流回路に接続されているマイコン７の内部に設けられている。 Reference numeral 70 denotes an AD converter (referred to as ADC) that converts analog data into digital data. Reference numeral 71 denotes a calculation unit that performs a calculation based on a signal output from the ADC 70. These 70 and 71 are provided inside the microcomputer 7 connected to the synchronous rectifier circuit.
また，本バンドパスフィルタ・同期整流回路の自動ゲイン調整回路には，校正モードと測定モードを切替えるためのモード切替え手段が３個設けられている。第一には，校正モードにおいては校正用矩形波発生回路１を，測定モードにおいては測定入力端子２をバンドパスフィルタに接続するための第一のモード切替え手段８が設けられており，これはメカニカルな切替えスイッチで構成されている。また半導体スイッチで構成してもよい。 The automatic gain adjustment circuit of the band-pass filter / synchronous rectifier circuit is provided with three mode switching means for switching between the calibration mode and the measurement mode. First, there is provided first mode switching means 8 for connecting the calibration rectangular wave generating circuit 1 in the calibration mode and the measurement input terminal 2 in the measurement mode to the bandpass filter. It consists of a mechanical changeover switch. Moreover, you may comprise with a semiconductor switch.
第二には，マイコン７の内部でソフトウエアの分岐処理として設けられた，第二のモード切替え手段７２で，校正モードにおいては校正モードの処理ルーチンに導き，測定モードにおいては測定モードの処理ルーチンに導くようプログラムされている。 Second, the second mode switching means 72 provided as a software branching process inside the microcomputer 7 leads to a calibration mode processing routine in the calibration mode, and a measurement mode processing routine in the measurement mode. Is programmed to lead to
第三には，校正モードにおいては波形成形回路５を，測定モードにおいては同期整流基準矩形波発生回路６を同期整流回路４に接続するもので，論理回路を用いて構成されている。なお，メカニカルまたは半導体のスイッチを用いて構成してもよいし，マイコン内部で実現しても良い。 Thirdly, the waveform shaping circuit 5 is connected to the synchronous rectification circuit 4 in the calibration mode and the synchronous rectification reference rectangular wave generation circuit 6 is connected to the synchronous rectification circuit 4 in the measurement mode. A mechanical or semiconductor switch may be used, or it may be realized inside the microcomputer.
このようにバンドパスフィルタ・同期整流回路を構成している。 In this way, a band-pass filter / synchronous rectifier circuit is configured.
次に，校正モードにおける動作について説明する。校正モードのときには，３つの切替え手段８，７２，９が校正モードに切替わり，まず校正用矩形波発生回路１から校正用矩形波ａがバンドパスフィルタ３に入力される。校正用矩形波は，装置を校正するときに用いるもので，定められた入力に対する演算後の出力値（期待値）を決めるためのものである。本発明においては，予め定められた校正用矩形波ａに対して期待される演算後の出力値（期待値）Ｗを用いて校正を行う。 Next, the operation in the calibration mode will be described. In the calibration mode, the three switching means 8, 72, 9 are switched to the calibration mode. First, the calibration rectangular wave a is input from the calibration rectangular wave generating circuit 1 to the bandpass filter 3. The calibration rectangular wave is used when the apparatus is calibrated, and is used to determine an output value (expected value) after calculation for a predetermined input. In the present invention, calibration is performed using an output value (expected value) W after calculation expected for a predetermined calibration rectangular wave a.
バンドパスフィルタ３は校正用矩形波ａの基本波だけを増幅して正弦波ａ１を出力する。したがって校正用矩形波ａの電圧レベル（例えば５Ｖ）から，測定結果になって欲しい値すなわち期待値Ｗが予め計算できる。つまり，校正用矩形波ａの電圧レベルから，基本波となる正弦波ａ１の電圧が計算でき，その基本波となる正弦波ａ１の電圧を入力したときの期待値Ｗが予め定まる。この期待値Ｗが，回路に用いる部品に誤差があるにもかかわらず出力させたい理想的な値となる。バンドパスフィルタ３を通過した入力正弦波ａ１は，同期整流回路４と，波形成形回路５とに入力される。波形成形回路５を通過した正弦波ａ１から矩形波ａ２が得られ，入力正弦波ａ１と該矩形波ａ２によって同期整流回路４は同期整流を行う。 The bandpass filter 3 amplifies only the fundamental wave of the calibration rectangular wave a and outputs a sine wave a1. Therefore, the desired value, that is, the expected value W can be calculated in advance from the voltage level (for example, 5 V) of the calibration rectangular wave a. That is, the voltage of the sine wave a1 serving as the fundamental wave can be calculated from the voltage level of the calibration rectangular wave a, and the expected value W when the voltage of the sine wave a1 serving as the fundamental wave is input is determined in advance. This expected value W is an ideal value that is desired to be output even though there is an error in the parts used in the circuit. The input sine wave a1 that has passed through the bandpass filter 3 is input to the synchronous rectification circuit 4 and the waveform shaping circuit 5. A rectangular wave a2 is obtained from the sine wave a1 that has passed through the waveform shaping circuit 5, and the synchronous rectification circuit 4 performs synchronous rectification by the input sine wave a1 and the rectangular wave a2.
校正することにより，経時的な部品の容量値や抵抗値などの変化や，温度変化による部品の容量値や抵抗値などの変化が原因となる測定誤差を防ぐことができる。 By calibrating, it is possible to prevent measurement errors caused by changes in the capacitance value and resistance value of the component over time and changes in the capacitance value and resistance value of the component due to temperature changes.
同期整流回路４の出力は，バンドパスフィルタ３の出力波形をゼロクロス点で折り返した全波整流波形の積分値となる。この出力値をマイコン７のＡＤＣ７０でＡＤ変換し，変換後の値（ＡＤＣ値という）Ｘが得られる。この値Ｘが，回路に用いられる部品の誤差を含んだ測定値となる。その後，ソフトウエア的に校正モードに切替えられた第二のモード切替え手段７２を経て，演算部７１にてＡＤＣ値Ｘと期待値Ｗとから増幅度（ゲイン）を表す定数Ｗ／Ｘが演算される。測定モードではこの定数Ｗ／Ｘを用いて測定を行う。 The output of the synchronous rectifier circuit 4 is an integrated value of a full-wave rectified waveform obtained by folding the output waveform of the bandpass filter 3 at the zero cross point. This output value is AD converted by the ADC 70 of the microcomputer 7 to obtain a converted value (referred to as an ADC value) X. This value X is a measured value including an error of a component used in the circuit. After that, through the second mode switching means 72 switched to the calibration mode by software, the arithmetic unit 71 calculates a constant W / X representing the amplification degree (gain) from the ADC value X and the expected value W. The In the measurement mode, measurement is performed using this constant W / X.
次に測定モードにおける操作について説明する。測定モードのときには，３つの切替え手段８，７２，９が測定モードに切替わり，まず測定入力端子２から測定入力ｂがバンドパスフィルタ３に入力される。バンドパスフィルタ３を通過して得られる正弦波ｂ１は同期整流回路４に入力される。また，第三のモード切替え手段９が測定モードに切替わることにより，同期整流基準矩形波発生回路６が同期整流回路４に接続される。同期整流基準矩形波発生回路６により同期整流回路４に入力される基準矩形波は予め抵抗分（Ｒ分）の出力が出るよう位相調整したものである。この基準矩形波の変化点を元に同期整流を行うため，回路条件における位相のずれを吸収して測定が行える。 Next, the operation in the measurement mode will be described. In the measurement mode, the three switching means 8, 72, 9 are switched to the measurement mode. First, the measurement input b is input from the measurement input terminal 2 to the bandpass filter 3. A sine wave b <b> 1 obtained by passing through the band pass filter 3 is input to the synchronous rectifier circuit 4. In addition, the synchronous rectification reference rectangular wave generation circuit 6 is connected to the synchronous rectification circuit 4 when the third mode switching means 9 is switched to the measurement mode. The reference rectangular wave input to the synchronous rectification circuit 4 by the synchronous rectification reference rectangular wave generation circuit 6 is phase-adjusted in advance so that an output of resistance (R) is output. Since synchronous rectification is performed based on the change point of the reference rectangular wave, measurement can be performed while absorbing the phase shift in the circuit conditions.
測定入力端子１からの入力ｂが抵抗成分（Ｒ分）の漏れ電流である場合，同期整流回路４の出力は，バンドパスフィルタ３の出力波形をゼロクロス点で折り返した全波整流波形の積分値となる。この出力値をマイコン７のＡＤＣ７０でＡＤ変換し，変換後の値（ＡＤＣ値という）Ｙが得られる。この値Ｙが，測定電路における測定値となる。その後，ソフトウエア的に測定モードに切替えられた第二のモード切替え手段７２を経て，演算部７１にて，ＡＤＣ値Ｙと校正モードで得たゲインを表す定数Ｗ／Ｘを用いて演算を行う。 When the input b from the measurement input terminal 1 is a leakage current of a resistance component (R), the output of the synchronous rectifier circuit 4 is the integrated value of the full-wave rectified waveform obtained by folding the output waveform of the bandpass filter 3 at the zero cross point. It becomes. This output value is AD converted by the ADC 70 of the microcomputer 7 to obtain a converted value (referred to as an ADC value) Y. This value Y is a measurement value in the measurement circuit. Thereafter, the calculation unit 71 performs calculation using the ADC value Y and the constant W / X representing the gain obtained in the calibration mode through the second mode switching means 72 switched to the measurement mode by software. .
先に校正モードから得たゲインを表す定数をＧとすると，Ｇ＝Ｗ／Ｘにより，真の測定値をＡとした場合，Ａ＝Ｙ×Ｇ，すなわちＡ＝Ｙ×（Ｗ／Ｘ）で演算できる。このように校正によって得られたゲインＧ＝Ｗ／Ｘを用いることで，測定値は常に回路条件に左右されず正しいＲ分の漏れ電流を得ることができる。 Assuming that the constant representing the gain obtained from the calibration mode is G, if G = W / X and the true measured value is A, then A = Y × G, that is, A = Y × (W / X) Can be calculated. By using the gain G = W / X obtained by calibration in this way, the measured value can always obtain a leakage current of R that is correct regardless of the circuit conditions.
このように本発明の方法によれば，従来必要であった半固定抵抗を調整する必要はなく自動的にゲイン調整が行なわれる。したがって調整のための時間それに伴うコストが不要になり，図３のようなゲイン調整回路が不要になるのでコストの上昇を抑えることができる。また経年変化における部品の容量値や抵抗値のずれに伴うメンテナンス作業作業が不要になりコストの上昇を抑えることができる。 As described above, according to the method of the present invention, it is not necessary to adjust the semi-fixed resistance, which has been conventionally required, and gain adjustment is automatically performed. Therefore, the time required for the adjustment and the cost associated with it become unnecessary, and the gain adjustment circuit as shown in FIG. 3 becomes unnecessary, so that an increase in cost can be suppressed. In addition, maintenance work associated with deviations in the capacitance values and resistance values of components due to secular changes is no longer necessary, and an increase in cost can be suppressed.
なお，完全に調整を無くすための要件として，バンドパスフィルタ・同期整流回路の波形を飽和させないことが必要である。このためには，例えば入力電圧の最大値を，手作業により半固定抵抗で調整していたときの半分にしておけば良い。測定信号の大きさが半分になるが，ＡＤＣの精度を上げたり，ＡＤＣ読み取り回数を増やしてみかけ上精度が同じになるようにすれば，ほぼ測定精度を保って測定値を得ることができる。ＡＤＣの精度を上げるのは，専用のＡＤＣ素子を用いるか，マイコンのカウンタを用いた積分型にするか，レンジ切り替えするか，高精度のＡＤＣ内蔵のマイコンを使うかなどで実現する事ができる。 As a requirement to completely eliminate the adjustment, it is necessary not to saturate the waveform of the bandpass filter / synchronous rectifier circuit. For this purpose, for example, the maximum value of the input voltage may be halved when it is manually adjusted with a semi-fixed resistor. Although the magnitude of the measurement signal is halved, if the accuracy of ADC is increased or the number of ADC readings is increased so that the apparent accuracy is the same, a measurement value can be obtained with almost the same measurement accuracy. The ADC accuracy can be improved by using a dedicated ADC element, integrating with a microcomputer counter, switching the range, or using a microcomputer with a high precision ADC. .
次に，校正用矩形波発生回路１について説明する。図４は校正用矩形波の発生回路の例である。マイコンの出力をＣＭＯＳのＩＣ４２で強化して出力している。マイコンの電源に用いるスイッチング電源は±５％のものが得られるので，この回路ではほぼ±５％の精度で調整可能となる。 Next, the calibration rectangular wave generating circuit 1 will be described. FIG. 4 shows an example of a calibration rectangular wave generating circuit. The output of the microcomputer is enhanced by a CMOS IC 42 and output. Since the switching power supply used for the power supply of the microcomputer is ± 5%, this circuit can be adjusted with an accuracy of almost ± 5%.
図５には校正用矩形波発生回路１の他の例を示している。基準電圧ＩＣ５３によりの安定した電圧を供給できる。基準電圧ＩＣ５３の精度は±０．５％のものが容易に入手できる。したがって±０．５％程度の精度の調整が容易に実現可能となる。 FIG. 5 shows another example of the calibration rectangular wave generating circuit 1. A stable voltage can be supplied by the reference voltage IC53. A reference voltage IC53 having an accuracy of ± 0.5% can be easily obtained. Therefore, an adjustment with an accuracy of about ± 0.5% can be easily realized.
図６には校正用矩形波発生回路１のその他の例として，バンドパスフィルタ部の入力が電流入力の場合の回路例を示している。ＣＭＯＳインバータＩＣ６５の出力電圧が０Ｖまたは５Ｖであるので，抵抗Ｒ６２をＲ６１の２倍，即ちＲ６２＝２×Ｒ６１にすると，校正用矩形波の電流のＤＣ成分を０にでき，バンドパスフィルタ部の入力をモード切替により切り替えた際の波形の乱れを少なくする事ができる。精度は上の例と比べると±１０％と下がるが，切替えスピードを早くできる。 FIG. 6 shows a circuit example when the input of the bandpass filter unit is a current input as another example of the calibration rectangular wave generating circuit 1. Since the output voltage of the CMOS inverter IC 65 is 0V or 5V, if the resistor R62 is set to twice R61, that is, R62 = 2 × R61, the DC component of the current of the calibration rectangular wave can be reduced to 0, and the bandpass filter section Waveform disturbance when the input is switched by mode switching can be reduced. The accuracy drops to ± 10% compared to the above example, but the switching speed can be increased.
図２は本発明の方法を適用した直流電路地絡検出装置の例を示している。複数の電路のうち，電路１に地絡ＲＥが発生した場合を示している。電路には零相変流器であるＺＣＴ（１）〜ＺＣＴ（ｎ）が設けられており，該ＺＣＴは直流電路地絡検出装置に接続されている。また，本直流電路地絡検出装置には先に説明したバンドパスフィルタ・同期整流回路が設けられている。 FIG. 2 shows an example of a DC circuit ground fault detection apparatus to which the method of the present invention is applied. A case where a ground fault RE occurs in the electric circuit 1 among the plurality of electric circuits is shown. ZCT (1) to ZCT (n), which are zero-phase current transformers, are provided in the electric circuit, and the ZCT is connected to a DC electric circuit ground fault detector. The DC circuit ground fault detection device is provided with the bandpass filter / synchronous rectifier circuit described above.
地絡ＲＥの無い通常時は，直流回路のＰ極，アース極，Ｎ極は直流地絡継電器６４Ｄ（図示しない）に接続されている。通常時には，直流電路地絡検出装置１２はマイコンに記憶されたプログラムにより，校正モードで動作するようにセットされている。１１は直流電源であり，電路に電源を供給している。 In normal times without a ground fault RE, the P pole, ground pole, and N pole of the DC circuit are connected to a DC ground fault relay 64D (not shown). At normal time, the DC circuit ground fault detector 12 is set to operate in the calibration mode by a program stored in the microcomputer. Reference numeral 11 denotes a DC power supply, which supplies power to the electric circuit.
地絡ＲＥが発生すると，電路に接続されている直流地絡継電器６４Ｄは起動信号を出力する。該起動信号を起動信号受信部（図示しない）にて受信した直流電路地絡検出装置１２は直流地絡継電器６４Ｄに代わって電路のＰ極，アース極，Ｎ極が接続され，直流電路地絡検出装置１２は測定モードに切り変わる。交流信号の生成回路により，電路に低周波の正弦波電圧が生成され，該生成された正弦波電圧はアースから地絡ＲＥを経てＺＣＴ１を流れるため，ＺＣＴ１からの出力をバンドパスフィルタ・同期整流回路で受けて抵抗成分の漏れ電流を検出することが可能である。 When the ground fault RE occurs, the DC ground fault relay 64D connected to the electric circuit outputs a start signal. The DC circuit ground fault detection device 12 that has received the startup signal at a startup signal receiving unit (not shown) is connected to the P pole, ground electrode, and N pole of the circuit instead of the DC ground fault relay 64D. 12 switches to the measurement mode. The AC signal generation circuit generates a low-frequency sine wave voltage in the electric circuit, and the generated sine wave voltage flows from the ground through the ground fault RE through the ZCT 1, so the output from the ZCT 1 is a band-pass filter / synchronous rectification. It is possible to detect the leakage current of the resistance component received by the circuit.
地絡の発生時期は予測しがたく，装置の設置後，相当な期間を経ている場合もままある。しかしながら，直流電路地絡検出装置は，通常時には校正モードで動作を行っているため，直流継電器６４Ｄから起動信号を受信する直前まで常に回路の校正を行い，その時々の最新のゲインＧを得ている。このため，部品の容量値や抵抗値の経年変化に左右されることなく，地絡が発生した場合には最新のゲインＧを用いて測定値から真の測定値を演算することが出来，抵抗成分の地絡電流の値を正確に検出することができる。 The time of occurrence of a ground fault is difficult to predict, and there are cases where a considerable period has passed since the installation of the equipment. However, since the DC circuit ground fault detection device normally operates in the calibration mode, the circuit is always calibrated until just before the start signal is received from the DC relay 64D, and the latest gain G is obtained at that time. . For this reason, when a ground fault occurs, the true measured value can be calculated from the measured value using the latest gain G, regardless of the secular change of the capacitance value and resistance value of the component. The value of the ground fault current of the component can be accurately detected.
本発明はバンドパスフィルタ・同期整流回路に適用できる方法であるため、バンドパスフィルタ・同期整流回路を用いる電流や電圧のベクトル測定の分野に適用できる。また，自動でゲイン調整を行うため回路の小型化により，操作が簡単な携帯型の地絡検出装置への適用も考えられる。また同期整流用の矩形波をＣ成分に合せることにより，Ｃの測定装置へも適用できる。なお，本発明における抵抗成分漏れ電流の出力を得るために同期整流の出力を用いているが，該同期整流の出力として，折り返した波形を生成信号の周期の整数倍時間積分した値を用いて測定を行い，出力値を増大させることでより正確な測定が行えるようになるという可能性がある。 Since the present invention is a method applicable to a bandpass filter / synchronous rectifier circuit, it can be applied to the field of current and voltage vector measurement using a bandpass filter / synchronous rectifier circuit. In addition, automatic gain adjustment can be applied to a portable ground fault detection device that is easy to operate by downsizing the circuit. Further, it can be applied to a C measuring device by matching a rectangular wave for synchronous rectification with a C component. In addition, in order to obtain the output of the resistance component leakage current in the present invention, the output of the synchronous rectification is used. As the output of the synchronous rectification, a value obtained by integrating the folded waveform with an integral multiple of the period of the generated signal is used. There is a possibility that more accurate measurement can be performed by measuring and increasing the output value.
１ 校正用矩形波発生回路
２ 測定入力端子
３ バンドパスフィルタ
４ 同期整流回路
５ 波形成形回路
６ 同期整流基準矩形波発生回路
７ マイコン
７０ ＡＤ変換部
７１ 演算部
１１ 直流電源
１２ 直流電路地絡検出装置
３１ オペアンプ
４２ ＣＭＯＳインバータ
５３ 基準電圧ＩＣ
５４ オペアンプ
６５ ＣＭＯＳインバータ
DESCRIPTION OF SYMBOLS 1 Calibration rectangular wave generation circuit 2 Measurement input terminal 3 Band pass filter 4 Synchronous rectification circuit 5 Waveform shaping circuit 6 Synchronous rectification reference rectangular wave generation circuit 7 Microcomputer 70 AD conversion part 71 Calculation part 11 DC power supply 12 DC electric circuit ground fault detection apparatus 31 Operational amplifier 42 CMOS inverter 53 Reference voltage IC
54 operational amplifier 65 CMOS inverter
Claims (2)
直流電路に接続された零相変流器ＺＣＴによって検出する直流電路地絡検出装置において，該直流電路地絡検出装置に内蔵されたバンドパスフィルタ・同期整流回路を校正モードと測定モードとに切替えるモード切替手段を備え，
校正モードにおいては，校正用矩形波発生回路から，直流電路地絡検出装置内部でＺＣＴを介さずに前記バンドパスフィルタに校正用矩形波ａを入力され，該バンドパスフィルタを通過して得られる正弦波ａ１は，同期整流回路と波形成形回路とに入力され，該波形成形回路を通過して得られる矩形波ａ２によって同期整流回路は同期整流を行い，同期整流した出力をＡＤ変換部にてＡＤ変換して値Ｘを得，該値Ｘと，校正用矩形波ａに対する出力の期待値Ｗ
からバンドパスフィルタの増幅度（ゲイン）を表す定数Ｗ／Ｘを演算部により演算し，
測定モードにおいては，前記バンドパスフィルタに測定入力端子から測定入力ｂが入力され，該バンドパスフィルタを通過して得られる正弦波ｂ１は前記同期整流回路に入力されるとともに，同期整流回路は，同期整流基準矩形波発生回路から発生される基準矩形波ｃによって同期整流を行い，同期整流した出力をＡＤ変換部にてＡＤ変換して値Ｙを得，
該値Ｙと前記定数Ｗ／Ｘを用いて，
測定結果の値Ａ＝Ｙ×Ｗ／Ｘ
を演算部により演算することにより，測定結果の値を得ることを特徴とする直流電路地絡検出装置に内蔵されたバンドパスフィルタ・同期整流回路のゲイン調整方法。 When a DC ground fault occurs, it is connected to a DC circuit in place of the DC ground fault relay 64D, an AC signal is generated between the N pole and the ground of the DC circuit, and a leakage current flowing from the AC signal to the ground fault resistance is generated. ,
In a DC circuit ground fault detection device that detects by a zero-phase current transformer ZCT connected to the DC circuit, a mode switch that switches the band-pass filter / synchronous rectifier circuit built in the DC circuit ground fault detection device between a calibration mode and a measurement mode. With means,
In the calibration mode, the calibration rectangular wave a is input from the calibration rectangular wave generation circuit to the bandpass filter without passing through the ZCT inside the DC circuit ground fault detection device , and is obtained by passing through the bandpass filter. The wave a1 is input to the synchronous rectification circuit and the waveform shaping circuit, and the synchronous rectification circuit performs synchronous rectification by the rectangular wave a2 obtained by passing through the waveform shaping circuit. A value X is obtained by conversion, and the expected value W of the output for the value X and the calibration rectangular wave a
To calculate a constant W / X representing the amplification factor (gain) of the bandpass filter by the calculation unit,
In the measurement mode, the measurement input b is input from the measurement input terminal to the bandpass filter, the sine wave b1 obtained by passing through the bandpass filter is input to the synchronous rectifier circuit, Synchronous rectification is performed by the reference rectangular wave c generated from the synchronous rectification reference rectangular wave generation circuit, and the value Y is obtained by performing AD conversion on the synchronously rectified output by the AD conversion unit,
Using the value Y and the constant W / X,
Measurement result value A = Y × W / X
A gain adjustment method for a band-pass filter / synchronous rectifier circuit built in the DC circuit ground fault detection device, wherein the value of the measurement result is obtained by calculating the value of the signal by a calculation unit.
常には校正モードで動作され，電路に接続された直流地絡過電圧継電器６４Ｄからの起動信号を起動信号受信部にて受信した場合には，モード切替手段により測定モードに切替り，該測定モードにて動作することを特徴とした請求項１記載のゲイン調整方法を用いた直流電路地絡検出装置。
In the DC circuit ground fault detection device,
When the activation signal receiving unit receives the activation signal from the DC ground fault overvoltage relay 64D connected to the electric circuit, the operation mode is switched to the measurement mode by the mode switching means. The DC circuit ground fault detection device using the gain adjustment method according to claim 1, wherein
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