JP6086271B1 - Isolated operation detection device - Google Patents

Isolated operation detection device Download PDF

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JP6086271B1
JP6086271B1 JP2016003224A JP2016003224A JP6086271B1 JP 6086271 B1 JP6086271 B1 JP 6086271B1 JP 2016003224 A JP2016003224 A JP 2016003224A JP 2016003224 A JP2016003224 A JP 2016003224A JP 6086271 B1 JP6086271 B1 JP 6086271B1
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洋介 森嶋
洋介 森嶋
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Fuji Electric Co Ltd
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Abstract

【課題】単独運転以外の要因によって系統周波数が変動し、周波数偏差が発生している場合に注入無効電力を０にする処理を可能にして、電力系統の擾乱を防止するようにした単独運転検出装置を提供する。【解決手段】分散型電源としての直流電源装置１を、パワーコンディショナー１０のインバータ１１を介して電力系統２０に連系させて運転する系統連系システムであって、インバータ１１により電力系統２０に変動する無効電力を注入した時の系統電圧の周波数偏差に基づいて直流電源装置１の単独運転状態を検出する単独運転検出装置において、系統電圧の周波数偏差が所定の正負の閾値をそれぞれ一定時間内に超えた場合に、電力系統２０に注入する無効電力を０にする無効電力注入判定手段１４を備える。【選択図】図１[PROBLEMS] To detect an isolated operation in which a system frequency fluctuates due to a factor other than an isolated operation and a process of setting an injection reactive power to 0 is possible when a frequency deviation occurs to prevent disturbance of the power system. Providing equipment. A system interconnection system in which a DC power supply device 1 as a distributed power source is operated by being connected to an electric power system 20 via an inverter 11 of a power conditioner 10, and the electric power system 20 is changed by the inverter 11. In the isolated operation detection device for detecting the isolated operation state of the DC power supply device 1 based on the frequency deviation of the system voltage when the reactive power to be injected is injected, the frequency deviation of the system voltage has a predetermined positive / negative threshold value within a predetermined time. When it exceeds, the reactive power injection determination means 14 which sets the reactive power injected into the electric power system 20 to 0 is provided. [Selection] Figure 1

Description

本発明は、例えば、太陽光発電装置、風力発電装置、燃料電池発電装置等の分散型電源が電力系統に連系運転している系統連系システムにおいて、分散型電源が単独運転状態にあることを検出する単独運転検出装置に関するものである。   The present invention relates to, for example, a grid-connected system in which a distributed power source such as a solar power generation device, a wind power generation device, or a fuel cell power generation device is connected to a power system. The present invention relates to a stand-alone operation detection device for detecting the above.

この種の系統連系システムにおいて、電力系統に事故が発生して変電所の遮断器が開放され、負荷への電力供給が停止された場合、分散型電源を系統に連系したまま運転すると、本来は停電状態となるべき電力系統に分散型電源から逆潮流が流れ込むことになり、感電事故等を引き起こす恐れがある。このため、分散型電源の単独運転状態を確実に検出して連系リレー等を遮断することにより、分散型電源を電力系統から解列することが求められる。   In this type of grid connection system, when an accident occurs in the power system, the circuit breaker of the substation is opened, and power supply to the load is stopped, if the distributed power source is operated while being connected to the grid, The reverse power flow from the distributed power source into the power system that should be in a power failure state may cause an electric shock accident or the like. For this reason, it is required to disconnect the distributed power source from the power system by reliably detecting the isolated operation state of the distributed power source and cutting off the interconnection relay and the like.

従来、分散型電源の単独運転を検出する方式には、単独運転への移行時に発生する電圧や位相の変化をとらえて検出する受動方式と、分散型電源を電力系統に連系させるインバータの出力に変動要因を与えておき、電力系統が健全である連系運転時にはその変動の影響が現れず、分散型電源の単独運転時には変動の影響が現れることを利用して検出する能動方式とがある。   Conventional methods to detect isolated operation of distributed power sources include passive methods that detect and detect voltage and phase changes that occur during the transition to isolated operation, and inverter outputs that link distributed power sources to the power system. There is an active method that uses the fact that the influence of the fluctuation does not appear in the interconnected operation where the power system is healthy, and the influence of the fluctuation appears in the single operation of the distributed power source. .

ここで、能動方式による単独運転検出装置としては、例えば、特許文献１に記載されたものが知られている。
特許文献１に係る単独運転検出装置は、商用電力系統に注入した無効電力の周波数変動に基づいて単独運転を検出する単独運転検出装置において、系統周期の１／３以下に相当する周期単位で系統周期を計測する系統周期計測手段と、順次計測した系統周期に基づき、連続した所定期間における系統周期の移動平均値を順次算出する移動平均値算出手段と、これらの移動平均値の偏差を系統周期ごとに算出する偏差量算出手段と、この偏差に基づいて系統への注入無効電力量を算出する無効電力量算出手段と、を備えている。
この従来技術によれば、系統周期の移動平均値の偏差、言い換えれば周波数偏差が小さい不感帯範囲内であっても、分散型電源の単独運転を高速に検出することが可能である。 Here, as an isolated operation detection device using an active method, for example, the one described in Patent Document 1 is known.
An isolated operation detection device according to Patent Document 1 is an isolated operation detection device that detects an isolated operation based on a frequency variation of reactive power injected into a commercial power system. A system cycle measuring means for measuring the cycle, a moving average value calculating means for sequentially calculating the moving average value of the system cycle in a predetermined continuous period based on the sequentially measured system cycle, and the deviation of these moving average values as the system cycle Deviation amount calculating means for calculating each time, and reactive power amount calculating means for calculating the amount of reactive power injected into the system based on the deviation.
According to this prior art, it is possible to detect isolated operation of a distributed power source at high speed even within a dead band range in which the deviation of the moving average value of the system cycle, in other words, the frequency deviation is small.

特許第４５５２９１３号（段落［００３８］〜［００５１］、図１，図７等）Japanese Patent No. 4552913 (paragraphs [0038] to [0051], FIG. 1, FIG. 7, etc.)

特許文献１のように周波数偏差に応じて注入無効電力量を算出する単独運転検出装置において、単独運転以外の要因により系統周波数に擾乱が生じたとしても、周波数偏差が大きい場合には、単独運転発生と誤認して系統に無効電力が注入されることとなる。この場合、分散型電源に対して系統が強ければ問題がないが、電力過疎地域や離島のように系統が脆弱である場合には、無効電力の注入によって系統の擾乱が一層助長されてしまう。
また、特許文献１では、系統への注入無効電力は周波数偏差に応じて決まるので、無効電力の注入によって周波数が変動する系統では、その注入動作を停止しない限り系統周波数が変動し続ける。このため、電力の安定性が損なわれるという問題があった。 In the isolated operation detection device that calculates the reactive energy to be injected according to the frequency deviation as in Patent Document 1, even if a disturbance occurs in the system frequency due to factors other than the isolated operation, the isolated operation is performed when the frequency deviation is large. It will be mistaken for occurrence and reactive power will be injected into the grid. In this case, there is no problem if the system is strong with respect to the distributed power source. However, when the system is fragile, such as a power depopulated area or a remote island, disturbance of the system is further promoted by injection of reactive power.
In Patent Document 1, the reactive power injected into the system is determined according to the frequency deviation. Therefore, in a system in which the frequency changes due to the injection of reactive power, the system frequency continues to change unless the injection operation is stopped. For this reason, there existed a problem that stability of electric power was impaired.

そこで、本発明の解決課題は、単独運転以外の要因によって系統周波数が変動し、周波数偏差が発生している場合に注入無効電力を０にする処理を可能にして、電力系統の擾乱を防止するようにした単独運転検出装置を提供することにある。   Therefore, the problem to be solved by the present invention is to enable the process of reducing the injection reactive power to 0 when the system frequency fluctuates due to factors other than the single operation and the frequency deviation occurs, thereby preventing disturbance of the power system. An object of the present invention is to provide an isolated operation detection device.

上記課題を解決するため、請求項１に係る発明は、分散型電源としての直流電源装置を、インバータを介して電力系統に連系させて運転する系統連系システムであって、前記インバータにより前記電力系統に無効電力を注入した時の系統電圧の周波数偏差に基づいて前記直流電源装置の単独運転状態を検出する単独運転検出装置において、
前記系統電圧の立上りゼロクロスカウント値及び立下りゼロクロスカウント値の各平均値とそれぞれの今回検出値との差分から第１の周波数偏差ΔＦ ｒｉｓｅ 及び第２の周波数偏差ΔＦ ｆａｌｌ を算出する周波数偏差算出手段と、
前記第１の周波数偏差ΔＦ ｒｉｓｅ または第２の周波数偏差ΔＦ ｆａｌｌ が正負の閾値をそれぞれ一定時間内に超えた場合に、前記電力系統に注入する無効電力を０にする無効電力注入判定手段と、を備え、
前記無効電力注入判定手段は、
前記第１の周波数偏差ΔＦ ｒｉｓｅ 及び第２の周波数偏差ΔＦ ｆａｌｌ のそれぞれについて、第１の閾値としての正の閾値を一定時間内に超えて増加し、かつ、第２の閾値としての負の閾値を一定時間内に超えて減少したことを時系列的に判定するパターンを複数有し、前記第１の周波数偏差ΔＦ ｒｉｓｅ または第２の周波数偏差ΔＦ ｆａｌｌ が前記パターンの何れかに該当する場合に、前記電力系統に注入する無効電力を０にすることを特徴とする。 In order to solve the above-mentioned problem, the invention according to claim 1 is a grid-connected system that operates a DC power supply device as a distributed power source linked to a power system via an inverter, and In the single operation detection device that detects the single operation state of the DC power supply based on the frequency deviation of the system voltage when reactive power is injected into the power system,
Frequency deviation calculating means for calculating the first frequency deviation ΔF rise and the second frequency deviation ΔF fall from the difference between the average value of the rising zero cross count value and the falling zero cross count value of the system voltage and the respective detected values. When,
Reactive power injection determining means for setting the reactive power to be injected to the power system to 0 when the first frequency deviation ΔF rise or the second frequency deviation ΔF fall exceeds a positive / negative threshold value within a predetermined time, equipped with a,
The reactive power injection determining means includes
About each of said 1st frequency deviation (DELTA) Frise and 2nd frequency deviation (DELTA) Ffall , the positive threshold value as a 1st threshold value is exceeded within a fixed time, and the negative threshold value as a 2nd threshold value is increased. When there is a plurality of patterns that determine in a time series that the first frequency deviation ΔF rise or the second frequency deviation ΔF fall corresponds to one of the patterns. The reactive power injected into the power system is set to zero .

本発明によれば、単独運転以外の要因によって系統に周波数変動が生じている場合に注入無効電力を０にする処理を追加したため、連系運転時に系統の擾乱が助長されるのを防ぐことができる。
また、注入無効電力を０にするための判定を、複数の閾値を用いて多段階で実行することにより、検出するべき単独運転状態を検出するための本来の無効電力の注入動作に支障をきたすおそれがなく、単独運転状態の検出遅れを生じることもない。
更に、系統の周波数偏差が閾値を跨がないような周波数変動であれば、注入無効電力を０にする処理を行わず、周波数偏差に応じて無効電力を注入するモードとして単独運転状態を確実に検出することができる。 According to the present invention, since a process for reducing the injection reactive power to 0 when a frequency fluctuation occurs in the system due to factors other than the single operation, it is possible to prevent the disturbance of the system from being promoted during the interconnection operation. it can.
In addition, by executing the determination for setting the injection reactive power to 0 in multiple stages using a plurality of threshold values, the original reactive power injection operation for detecting the isolated operation state to be detected is hindered. There is no fear, and there is no detection delay in the isolated operation state.
Furthermore, if the frequency deviation of the system does not cross the threshold value, the process of setting the injection reactive power to 0 is not performed, and the single operation state is ensured as the mode for injecting the reactive power according to the frequency deviation. Can be detected.

本発明の実施形態が適用される系統連系システムの構成図である。1 is a configuration diagram of a grid interconnection system to which an embodiment of the present invention is applied. 図１における系統周波数検出手段の動作説明図である。It is operation | movement explanatory drawing of the system frequency detection means in FIG. 図１における周波数偏差算出手段の構成図である。It is a block diagram of the frequency deviation calculation means in FIG. 図１における無効電力注入判定手段の処理を示すフローチャートである。It is a flowchart which shows the process of the reactive power injection | pouring determination means in FIG. 図１における無効電力注入判定手段の処理を示すフローチャートである。It is a flowchart which shows the process of the reactive power injection | pouring determination means in FIG. 図１における無効電力注入判定手段の処理を示すフローチャートである。It is a flowchart which shows the process of the reactive power injection | pouring determination means in FIG. 図１における無効電力注入判定手段の処理を示すフローチャートである。It is a flowchart which shows the process of the reactive power injection | pouring determination means in FIG. 図１の無効電力注入判定手段の動作説明図である。It is operation | movement explanatory drawing of the reactive power injection | pouring determination means of FIG. 図１の無効電力注入指令手段の動作説明図である。It is operation | movement explanatory drawing of the reactive power injection instruction | indication means of FIG.

以下、図に沿って本発明の実施形態を説明する。
図１は、本実施形態が適用される系統連系システムの構成図である。図１において、太陽光発電装置等の直流電源装置１から出力された直流電力は、パワーコンディショナー１０により電力系統２０と同期した交流電力に変換されて出力される。また、事業所や家庭に相当する負荷３０には、電力系統２０からの交流電力及びパワーコンディショナー１０からの交流電力を供給可能に構成されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a grid interconnection system to which the present embodiment is applied. In FIG. 1, DC power output from a DC power supply device 1 such as a solar power generation device is converted into AC power synchronized with a power system 20 by a power conditioner 10 and output. Further, the load 30 corresponding to the office or home is configured to be able to supply AC power from the power system 20 and AC power from the power conditioner 10.

パワーコンディショナー１０の内部構成は、以下の通りである。
すなわち、１１は、半導体スイッチング素子のオン・オフにより直流電力を電力系統２０と同期した交流電力に変換するインバータ、１２は、インバータ１１の出力電圧から系統周波数を検出する周波数検出手段、１３は、今回サンプリング時点の周波数検出値と内部に保持している前回サンプリング時点の周波数検出値との偏差を算出する周波数偏差算出手段、１４は、周波数偏差算出手段１３が算出した周波数偏差に基づき無効電力注入の要否を判定して後述の無効電力マスク指令を出力する無効電力注入判定手段、１５は、上記周波数偏差に応じて電力系統２０に注入するべき無効電力を演算する注入無効電力演算手段、１６は、無効電力注入判定手段１４から無効電力マスク指令が入力される場合を除いて注入無効電力演算手段１５が演算した無効電力の注入指令を出力する無効電力注入指令手段、１７は、周波数偏差算出手段１３が算出した周波数偏差と注入無効電力演算手段１５が演算した注入無効電力とに基づいて、直流電源装置１が単独運転状態であるか否かを検出する単独運転検出手段、１８は、系統周波数検出手段１２からの周波数検出値、無効電力注入指令手段１６からの無効電力注入指令、及び単独運転検出手段１７からの単独運転検出信号に基づいてインバータ１１を駆動制御するインバータ制御手段、１９は、直流電源装置１が単独運転時に単独運転検出手段１７の出力信号によりインバータ１１を電力系統２０から遮断するための連系リレーである。 The internal configuration of the power conditioner 10 is as follows.
That is, 11 is an inverter that converts DC power into AC power synchronized with the power system 20 by turning on and off the semiconductor switching element, 12 is a frequency detection means that detects the system frequency from the output voltage of the inverter 11, and 13 is Frequency deviation calculating means 14 for calculating a deviation between the frequency detection value at the current sampling time and the frequency detection value at the previous sampling time held therein, 14 is a reactive power injection based on the frequency deviation calculated by the frequency deviation calculating means 13. Reactive power injection determining means 15 for determining whether or not necessary and outputting a reactive power mask command to be described later, 15 injection reactive power calculating means for calculating reactive power to be injected into the power system 20 according to the frequency deviation, 16 Except for the case where a reactive power mask command is input from the reactive power injection determination means 14, the injection reactive power calculation means 15 The reactive power injection command means 17 for outputting the calculated reactive power injection command, 17 is a DC power supply based on the frequency deviation calculated by the frequency deviation calculation means 13 and the injection reactive power calculated by the injection reactive power calculation means 15. 1 is an isolated operation detecting means for detecting whether or not 1 is in an isolated operation state, 18 is a frequency detection value from the system frequency detecting means 12, a reactive power injection command from the reactive power injection command means 16, and an isolated operation detection means. Inverter control means 19 for driving and controlling the inverter 11 on the basis of the isolated operation detection signal from 17, in order to shut off the inverter 11 from the power system 20 by the output signal of the isolated operation detection means 17 when the DC power supply device 1 is operated alone. This is an interconnection relay.

上記構成において、周波数偏差算出手段１３が算出する周波数偏差は、系統周波数の単周期における偏差でも良いが、測定誤差やノイズ誤差等の影響を排除するために数周期分の移動平均値から算出した偏差でもよい。   In the above configuration, the frequency deviation calculated by the frequency deviation calculating means 13 may be a deviation in a single cycle of the system frequency, but was calculated from a moving average value for several cycles in order to eliminate the influence of measurement error, noise error, etc. It may be a deviation.

また、注入無効電力演算手段１５は、周波数偏差算出手段１３が算出した周波数偏差に応じて電力系統２０への注入無効電力の大きさを変化させるようにし、周波数偏差が小さいときには注入無効電力を周波数偏差検出値×１段目ゲインにより求め、周波数偏差が大きくなってきたら注入無効電力を周波数偏差検出値×２段目ゲインにより求める。
ここで、上記の演算に使用するゲインを１段目ゲインまたは２段目ゲインに分ける周波数偏差の閾値は、例えば０．０１［Ｈｚ］とする。また、２段目ゲインを１段目ゲインよりも大きくすることにより、周波数偏差が小さい場合は注入無効電力を小さくして電力系統２０に与える影響を抑えておき、周波数偏差が大きくなってきたら、変化がより大きくなるように注入無効電力を大きくしている。 Further, the injection reactive power calculation means 15 changes the magnitude of the injection reactive power to the power system 20 according to the frequency deviation calculated by the frequency deviation calculation means 13, and when the frequency deviation is small, the injection reactive power is changed to the frequency. Deviation detection value × first-stage gain is obtained, and when the frequency deviation increases, injection reactive power is obtained by frequency deviation detection value × second-stage gain.
Here, the threshold value of the frequency deviation for dividing the gain used for the above calculation into the first stage gain or the second stage gain is, for example, 0.01 [Hz]. Further, by making the second stage gain larger than the first stage gain, if the frequency deviation is small, the influence on the power system 20 is suppressed by reducing the injection reactive power, and if the frequency deviation becomes large, The injection reactive power is increased so that the change becomes larger.

次に、図２は系統周波数検出手段１２の動作説明図である。
図２に示すように、系統電圧のゼロクロス点の立上りから次の立上りまでをカウントするカウンタがクリアされるときのカウント値をホールドし、このホールド値を周波数データとして扱う。系統電圧のゼロクロス点の立下りから次の立下りまでについても同様に、カウンタがクリアされるときのカウント値をホールドして周波数データとする。 Next, FIG. 2 is a diagram for explaining the operation of the system frequency detection means 12.
As shown in FIG. 2, the count value when the counter that counts from the rise of the zero cross point of the system voltage to the next rise is cleared is held, and this hold value is handled as frequency data. Similarly, from the fall of the zero cross point of the system voltage to the next fall, the count value when the counter is cleared is held and used as frequency data.

図３は、図１における周波数偏差算出手段１３の構成図である。
周波数偏差算出手段１３では、系統周波数検出手段１２が検出した立上り周波数データ（立上りゼロクロスカウント値）及び立下り周波数データ（立下りゼロクロスカウント値）に対して、周波数偏差ΔＦｒｉｓｅ，ΔＦｆａｌｌを算出する。
図３に示すように、ローパスフィルタ１３ａ，１３ｃ及び加減算手段１３ｂ，１３ｄを用いて、立上り周波数データ、立下り周波数データを平均化した値と今回の検出値との差分をそれぞれ求めることにより、周波数偏差ΔＦｒｉｓｅ，ΔＦｆａｌｌを算出する。ローパスフィルタ１３ａ，１３ｃとしては、例えば、系統電圧の周期に対して２０倍程度の時定数を持つものを使用する。 FIG. 3 is a block diagram of the frequency deviation calculating means 13 in FIG.
The frequency deviation calculating means 13 calculates frequency deviations ΔF rise and ΔF fall for the rising frequency data (rising zero cross count value) and falling frequency data (falling zero cross count value) detected by the system frequency detecting means 12. .
As shown in FIG. 3, by using the low-pass filters 13a and 13c and the addition / subtraction means 13b and 13d, the difference between the rising frequency data and the value obtained by averaging the falling frequency data and the detected value of this time is obtained. Deviations ΔF rise and ΔF fall are calculated. As the low-pass filters 13a and 13c, for example, those having a time constant of about 20 times the cycle of the system voltage are used.

次いで、図１の無効電力注入判定手段１４において無効電力を注入するか否かを判定する処理（１）〜（４）を、図４〜図７に基づいて説明する。
これらの図４〜図７では、判定の閾値を±０．０１［Ｈｚ］としているが、閾値はこれに限定されるものではなく、周波数偏差が前述した１段目ゲインとなるような値であればよい。 Next, processes (1) to (4) for determining whether or not reactive power is injected in the reactive power injection determination unit 14 of FIG. 1 will be described with reference to FIGS.
4 to 7, the threshold value for determination is ± 0.01 [Hz]. However, the threshold value is not limited to this, and the frequency deviation is a value that becomes the above-described first-stage gain. I just need it.

・処理（１）
図４において、無効電力を注入しないと判定する（無効電力マスクフラグをセットする）基準は、周波数偏差算出手段１３により算出された一方の周波数偏差ΔＦｒｉｓｅが＋０．０１［Ｈｚ］以上→−０．０１［Ｈｚ］以上→＋０．０１［Ｈｚ］以上というように０［Ｈｚ］をまたいで順に変化した場合、つまり、ΔＦｒｉｓｅが閾値に対して“増加→減少→増加”という順に変化した場合である。 ・ Process (1)
In FIG. 4, the criterion for determining that reactive power is not injected (setting the reactive power mask flag) is that one frequency deviation ΔF rise calculated by the frequency deviation calculating unit 13 is +0.01 [Hz] or more → −0 .01 [Hz] or higher → +0.01 [Hz] or higher, such as when changing in order across 0 [Hz], that is, when ΔF rise changes in the order of “increase → decrease → increase” with respect to the threshold It is.

すなわち、ΔＦｒｉｓｅが＋０．０１［Ｈｚ］以上であれば１段目フラグをセットし（ステップＳ１Ｙｅｓ，Ｓ２）、＋０．０１［Ｈｚ］未満であれば終了する（Ｓ１Ｎｏ）。
１段目フラグがセットされている状態で１００［ｍｓｅｃ］を経過する前にΔＦｒｉｓｅが−０．０１［Ｈｚ］以上（−０．０１［Ｈｚ］より負方向に大きい場合）になれば、２段目フラグをセットする（Ｓ３Ｙｅｓ，Ｓ５Ｙｅｓ，Ｓ６）。１００［ｍｓｅｃ］を経過する前に２段目フラグがセットされず、１段目フラグをセットしてから１００［ｍｓｅｃ］を経過した場合は、単独運転状態で一定方向に周波数が変動している可能性があるので、１段目フラグをリセットする（Ｓ３ＮＯ，Ｓ４）。 That is, if ΔF rise is +0.01 [Hz] or more, the first-stage flag is set (steps S1 Yes, S2), and if it is less than +0.01 [Hz], the process ends (S1 No).
If ΔF rise becomes −0.01 [Hz] or more (when larger than −0.01 [Hz]) before 100 [msec] elapses with the first stage flag set, The second stage flag is set (S3 Yes, S5 Yes, S6). If the second stage flag is not set before 100 [msec] has elapsed and 100 [msec] has elapsed since the first stage flag was set, the frequency fluctuates in a certain direction in the single operation state. Since there is a possibility, the first stage flag is reset (S3NO, S4).

次に、２段目フラグがセットされている状態で、１００［ｍｓｅｃ］を経過する前にΔＦｒｉｓｅが＋０．０１［Ｈｚ］以上になれば、３段目フラグをセットする（Ｓ７Ｙｅｓ，Ｓ９Ｙｅｓ，Ｓ１０）。１００［ｍｓｅｃ］を経過する前に３段目フラグがセットされず、２段目フラグをセットしてから１００［ｍｓｅｃ］を経過している場合は、一時的な擾乱によって周波数が変動しているか、または、擾乱後に単独運転状態に移行した可能性があるので、１段目フラグ及び２段目フラグをリセットする（Ｓ７Ｎｏ，Ｓ８）。 Next, when the second stage flag is set and ΔF rise becomes +0.01 [Hz] or more before 100 [msec] elapses, the third stage flag is set (S7 Yes, S9 Yes, S10). If the third stage flag is not set before 100 [msec] has elapsed and 100 [msec] has elapsed since the second stage flag was set, is the frequency fluctuating due to temporary disturbance? Or, since there is a possibility of shifting to the single operation state after the disturbance, the first stage flag and the second stage flag are reset (S7 No, S8).

３段目フラグがセットされると、無効電力マスクフラグ１をセットし（Ｓ１１）、注入無効電力を０にする処理に移行する。そして、セットしていた１段目フラグ、２段目フラグ、３段目フラグをリセットし（Ｓ１２）、無効電力マスクフラグ１のセットにより注入無効電力を０にする処理を、例えば４０［ｍｓｅｃ］の間、継続させる（Ｓ１３）。そして、４０［ｍｓｅｃ］経過したら無効電力マスクフラグ１をリセットし（Ｓ１３Ｙｅｓ，Ｓ１４）、前述したステップＳ１から再度、監視を行う。   When the third stage flag is set, the reactive power mask flag 1 is set (S11), and the process proceeds to a process for setting the injection reactive power to zero. Then, the first stage flag, the second stage flag, and the third stage flag that have been set are reset (S12), and the process of setting the injection reactive power to 0 by setting the reactive power mask flag 1 is, for example, 40 [msec]. (S13). When 40 [msec] elapses, the reactive power mask flag 1 is reset (S13 Yes, S14), and monitoring is performed again from step S1 described above.

・処理（２）
図５において、無効電力を注入しないと判定する基準は、ΔＦｒｉｓｅが−０．０１［Ｈｚ］以上→＋０．０１［Ｈｚ］以上→−０．０１［Ｈｚ］以上という順に変化した場合、つまり、ΔＦｒｉｓｅが“減少→増加→減少”という順に変化した場合である。
図５のステップＳ２１〜Ｓ３４の全体的な流れは図４のステップＳ１〜Ｓ１４と同様であるが、図５ではステップＳ２１，Ｓ２５，Ｓ２９における閾値の符号が図４のステップＳ１，Ｓ５，Ｓ９とそれぞれ異なり、また、ステップＳ３１，Ｓ３３，Ｓ３４におけるセットまたはリセットの対象が無効電力マスクフラグ２である点が図４のステップＳ１１，Ｓ１３，Ｓ１４とそれぞれ異なる。 ・ Process (2)
In FIG. 5, the criterion for determining that reactive power is not injected is when ΔF rise changes in the order of −0.01 [Hz] or higher → + 0.01 [Hz] or higher → −0.01 [Hz] or higher. , ΔF rise changes in the order of “decrease → increase → decrease”.
The overall flow of steps S21 to S34 in FIG. 5 is the same as that in steps S1 to S14 in FIG. 4, but in FIG. 5, the signs of the threshold values in steps S21, S25, and S29 are steps S1, S5, and S9 in FIG. They are different from each other, and are different from steps S11, S13, and S14 in FIG. 4 in that the reactive power mask flag 2 is set or reset in steps S31, S33, and S34.

・処理（３）
図６において、無効電力を注入しないと判定する基準は、周波数偏差算出手段１３により算出された他方の周波数偏差ΔＦｆａｌｌが＋０．０１［Ｈｚ］以上→−０．０１［Ｈｚ］以上→＋０．０１［Ｈｚ］以上という順に変化した場合、つまり、ΔＦｆａｌｌが“増加→減少→増加”という順に変化した場合である。
図６のステップＳ４１〜Ｓ５４の全体的な流れは図４のステップＳ１〜Ｓ１４と同様であるが、図６ではステップＳ４１，Ｓ４５，Ｓ４９におけるΔＦｆａｌｌが図４のステップＳ１，Ｓ５，Ｓ９におけるΔＦｒｉｓｅと異なり、また、ステップＳ５１，Ｓ５３，Ｓ５４におけるセットまたはリセットの対象が無効電力マスクフラグ３である点が図４のステップＳ１１，Ｓ１３，Ｓ１４とそれぞれ異なる。 ・ Process (3)
In FIG. 6, the criterion for determining that reactive power is not injected is that the other frequency deviation ΔF fall calculated by the frequency deviation calculating unit 13 is +0.01 [Hz] or more → −0.01 [Hz] or more → + 0. This is a case where ΔF fall changes in the order of “increase → decrease → increase”.
The overall flow of steps S41 to S54 in FIG. 6 is the same as that in steps S1 to S14 in FIG. 4, but in FIG. 6, ΔF fall in steps S41, S45, and S49 is ΔF in steps S1, S5, and S9 in FIG. Unlike the rise, and the reactive power mask flag 3 is set or reset in steps S51, S53, and S54, respectively, is different from steps S11, S13, and S14 in FIG.

・処理（４）
図７において、無効電力を注入しないと判定する基準は、ΔＦｆａｌｌが−０．０１［Ｈｚ］以上→＋０．０１［Ｈｚ］以上→−０．０１［Ｈｚ］以上という順に変化した場合、つまり、ΔＦｆａｌｌが“減少→増加→減少”という順に変化した場合である。
図７のステップＳ６１〜Ｓ７４の全体的な流れは図１のステップＳ１〜Ｓ１４と同様であるが、図７ではステップＳ６１，Ｓ６５，Ｓ６９におけるΔＦｆａｌｌ及び閾値の符号が図４のステップＳ１，Ｓ５，Ｓ９とそれぞれ異なり、また、ステップＳ７１，Ｓ７３，Ｓ７４におけるセットまたはリセットの対象が無効電力マスクフラグ４である点が図４のステップＳ１１，Ｓ１３，Ｓ１４とそれぞれ異なる。 ・ Process (4)
In FIG. 7, the criterion for determining that reactive power is not injected is when ΔF fall changes in the order of −0.01 [Hz] or higher → + 0.01 [Hz] or higher → −0.01 [Hz] or higher, that is, , ΔF fall changes in the order of “decrease → increase → decrease”.
The overall flow of steps S61 to S74 in FIG. 7 is the same as that in steps S1 to S14 in FIG. 1, but in FIG. 7, ΔF fall and the signs of the threshold values in steps S61, S65, and S69 are steps S1 and S5 in FIG. , S9, and the point that the target of set or reset in steps S71, S73, S74 is the reactive power mask flag 4 is different from steps S11, S13, S14 of FIG.

上述した処理（１）〜（４）を行った無効電力注入判定手段１４は、図８に示すように、無効電力マスクフラグ１〜４を論理和手段１４ａに入力し、これらの出力である無効電力マスク指令が図１の無効電力注入指令手段１６に入力される。
図９は、無効電力注入指令手段１６の動作を説明するためのものであり、切替スイッチ１６ａは、無効電力マスク指令が「ＴＲＵＥ（真）」である場合に「Ｔ」側、すなわち０側に接続され、無効電力マスク指令が「ＦＡＬＳＥ（偽）」である場合に「Ｆ」側、すなわち、図１の注入無効電力演算手段１５により周波数偏差に応じて演算された無効電力指令側に接続される。 As shown in FIG. 8, the reactive power injection determination unit 14 that has performed the above-described processes (1) to (4) inputs the reactive power mask flags 1 to 4 to the logical sum unit 14a, and outputs the invalid power. The power mask command is input to the reactive power injection command means 16 in FIG.
FIG. 9 is a diagram for explaining the operation of the reactive power injection command means 16, and the changeover switch 16 a moves to the “T” side, that is, the 0 side when the reactive power mask command is “TRUE (true)”. When the reactive power mask command is “FALSE” (false), it is connected to the “F” side, that is, the reactive power command side calculated according to the frequency deviation by the injection reactive power calculation means 15 of FIG. The

これにより、無効電力マスク指令の状態に応じて、注入無効電力を「０」とする指令、または、周波数偏差に応じた無効電力指令の何れかが選択されることになり、選択された指令が無効電力注入指令として図１のインバータ制御手段１８に出力される。従って、インバータ制御手段１８は、上記の無効電力注入指令に従ってインバータ１１を駆動することにより、０または所定量の無効電力が電力系統２０に注入されることとなる。   As a result, either the command for setting the injection reactive power to “0” or the reactive power command corresponding to the frequency deviation is selected according to the state of the reactive power mask command. The reactive power injection command is output to the inverter control means 18 of FIG. Accordingly, the inverter control means 18 drives the inverter 11 in accordance with the reactive power injection command described above, so that zero or a predetermined amount of reactive power is injected into the power system 20.

以上説明したように、本実施形態によれば、単独運転以外の要因による周波数変動に対しては注入無効電力を０とすることにより、連系運転時に系統の擾乱が助長されるのを防ぐことができる。
また、注入無効電力を０にするための判定を複数の閾値に基づいて多段階で実行すると共に、周波数偏差が閾値を跨がないような微小範囲の周波数変動を除外することにより、単独運転状態を検出するための本来の無効電力の注入動作に支障をきたすおそれもない。 As described above, according to the present embodiment, it is possible to prevent the disturbance of the system from being promoted during the interconnection operation by setting the injection reactive power to 0 with respect to the frequency fluctuation caused by factors other than the single operation. Can do.
In addition, the determination for setting the injection reactive power to 0 is performed in multiple stages based on a plurality of threshold values, and by removing frequency fluctuations in a minute range in which the frequency deviation does not cross the threshold values, the single operation state There is no possibility that the original reactive power injection operation for detecting the trouble will be hindered.

なお、上述した処理（１）〜（４）において、判定の閾値である周波数や１〜３段目フラグセットからの経過時間、無効電力マスクフラグ１〜４のセットからの経過時間等は、あくまで一例であり、これらに限定されないことはいうまでもない。   In the above-described processes (1) to (4), the frequency that is the determination threshold, the elapsed time from the first to third stage flag sets, the elapsed time from the reactive power mask flags 1 to 4 set, etc. Needless to say, the present invention is not limited to these examples.

１：直流電源装置
１０：パワーコンディショナー
１１：インバータ
１２：系統周波数検出手段
１３：周波数偏差算出手段
１３ａ，１３ｃ：ローパスフィルタ
１３ｂ，１３ｄ：加減算手段
１４：無効電力注入判定手段
１４ａ：論理和手段
１５：注入無効電力演算手段
１６：無効電力注入指令手段
１６ａ：切替スイッチ
１７：単独運転検出手段
１８：インバータ制御手段
１９：連系リレー
２０：電力系統
３０：負荷 1: DC power supply 10: Power conditioner 11: Inverter 12: System frequency detection means 13: Frequency deviation calculation means 13a, 13c: Low-pass filter 13b, 13d: Addition / subtraction means 14: Reactive power injection determination means 14a: Logical sum means 15: Injection reactive power calculation means 16: reactive power injection command means 16a: changeover switch 17: isolated operation detection means 18: inverter control means 19: interconnection relay 20: power system 30: load

Claims (1)

分散型電源としての直流電源装置を、インバータを介して電力系統に連系させて運転する系統連系システムであって、前記インバータにより前記電力系統に無効電力を注入した時の系統電圧の周波数偏差に基づいて前記直流電源装置の単独運転状態を検出する単独運転検出装置において、
前記系統電圧の立上りゼロクロスカウント値及び立下りゼロクロスカウント値の各平均値とそれぞれの今回検出値との差分から第１の周波数偏差ΔＦ ｒｉｓｅ 及び第２の周波数偏差ΔＦ ｆａｌｌ を算出する周波数偏差算出手段と、
前記第１の周波数偏差ΔＦ ｒｉｓｅ または第２の周波数偏差ΔＦ ｆａｌｌ が正負の閾値をそれぞれ一定時間内に超えた場合に、前記電力系統に注入する無効電力を０にする無効電力注入判定手段と、
を備え、
前記無効電力注入判定手段は、
前記第１の周波数偏差ΔＦ ｒｉｓｅ 及び第２の周波数偏差ΔＦ ｆａｌｌ のそれぞれについて、第１の閾値としての正の閾値を一定時間内に超えて増加し、かつ、第２の閾値としての負の閾値を一定時間内に超えて減少したことを時系列的に判定するパターンを複数有し、前記第１の周波数偏差ΔＦ ｒｉｓｅ または第２の周波数偏差ΔＦ ｆａｌｌ が前記パターンの何れかに該当する場合に、前記電力系統に注入する無効電力を０にすることを特徴とする単独運転検出装置。 A grid-connected system that operates a DC power supply device as a distributed power source linked to a power system via an inverter, and the frequency deviation of the system voltage when reactive power is injected into the power system by the inverter In the isolated operation detection device for detecting the isolated operation state of the DC power supply device based on
Frequency deviation calculating means for calculating the first frequency deviation ΔF rise and the second frequency deviation ΔF fall from the difference between the average value of the rising zero cross count value and the falling zero cross count value of the system voltage and the respective detected values. When,
Reactive power injection determining means for setting the reactive power to be injected to the power system to 0 when the first frequency deviation ΔF rise or the second frequency deviation ΔF fall exceeds a positive / negative threshold value within a predetermined time,
Equipped with a,
The reactive power injection determining means includes
About each of said 1st frequency deviation (DELTA) Frise and 2nd frequency deviation (DELTA) Ffall , the positive threshold value as a 1st threshold value is exceeded within a fixed time, and the negative threshold value as a 2nd threshold value is increased. When there is a plurality of patterns that determine in a time series that the first frequency deviation ΔF rise or the second frequency deviation ΔF fall corresponds to one of the patterns. A stand-alone operation detection apparatus , wherein the reactive power injected into the power system is set to zero .
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