JP4092949B2

JP4092949B2 - Wind power generator equipped with secondary battery, converter control device, and power converter control method

Info

Publication number: JP4092949B2
Application number: JP2002137904A
Authority: JP
Inventors: 輝菊池; 基生二見; 聡前川
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-05-14
Filing date: 2002-05-14
Publication date: 2008-05-28
Anticipated expiration: 2022-05-14
Also published as: JP2003333752A

Description

【０００１】
【発明の属する技術分野】
本発明は、風車によって駆動される同期発電機の出力変動を抑制する二次電池を備えた風力発電装置に関する。
【０００２】
【従来の技術】
従来技術の風力発電システムを説明する。風車は同期発電機に接続され、風のエネルギーで風車が回転し、風車が同期発電機を駆動して同期発電機が発電する。同期発電機が出力する交流電力を順変換器で直流電力に変換し、さらに逆変換器によって商用周波数の交流電力に変換して電力系統に供給している。このような従来技術の例が、特開２０００−３４５９５２号公報に開示されている。
【０００３】
このような従来技術の風力発電システムでは、出力電力が風速の変動に大きく影響される。風速変動に起因する出力変動は電力系統の周波数や電圧を変動させ、電力系統に影響を与えるので、風力発電システムを導入する場合には、このような出力電力の変動を抑制することが必須となる。そこで、風車のブレードの角度を風速に応じて変化させて、風車への機械的入力を調節するピッチ制御で風速変動に起因する出力変動を抑制する方法が採られている。さらに順変換器による同期発電機の出力制御も合わせて行われている。
【０００４】
【発明が解決しようとする課題】
上記従来技術においてピッチ制御では風から受けるトルクを逃がすために、特に定格以下の低風速領域で出力変動抑制を行うと、風車の利用率が低下する問題がある。風車では風のエネルギーを最も効率良く利用できるピッチの角度が決まっており、風車の利用率を向上するためには、最適な角度で運転することが最も良いが、そのような角度に設定すると出力変動が大きくなる。また、風が急に止んだ場合や風車が機械的なトラブル等によって急停止した場合には、風車のブレードが回転せず発電できないので、風車出力に変動が生じる。
【０００５】
本発明は、風力発電システムで風車の利用率を向上しつつ、出力電力の変動を抑制することを目的とする。
【０００６】
【課題を解決するための手段】
本発明の特徴の一つは、順変換器と逆変換器との間に設けられた二次電池と、同期発電機から出力される有効電力を検出する第１の有効電力検出器と、前記逆変換器から電力系統へ出力される有効電力を検出する第２の有効電力検出器と、を備え、順変換器制御器は、回転速度指令と前記風車の回転速度との偏差が入力され、風車の回転速度を制御する回転速度制御器と、前記順変換器から出力される有効電力を制御する第１の有効電力制御器と、を備え、逆変換器制御器は、第１の有効電力検出器の検出値および第２の有効電力検出器の検出値に応じて前記逆変換器から電力系統へ出力される有効電力を制御する第２の有効電力制御器を備え、前記回転速度制御器から出力される指令は前記第１の有効電力制御器に入力され、前記順変換器は前記第１の有効電力制御器の出力信号に応じて駆動される風力発電装置にある。
または、順変換器を制御する順変換器制御器と、逆変換器を制御する逆変換器制御器と、を備え、前記順変換器制御器は、回転速度指令と前記風車の回転速度との偏差が入力され、風車の回転速度を制御する回転速度制御器と、前記順変換器から出力される有効電力を制御する第１の有効電力制御器と、を備え、前記逆変換器制御器は、前記同期発電機から出力される有効電力および前記逆変換器から出力される有効電力の検出値に応じて前記逆変換器から電力系統へ出力される有効電力を制御する第２の有効電力制御器を備え、前記回転速度制御器から出力される指令は前記第１の有効電力制御器に入力され、前記順変換器制御器は前記第１の有効電力制御器の出力信号に応じて前記順変換器を駆動する変換器制御装置にある。
または、順変換器は、回転速度指令と前記風車の回転速度との偏差が入力され、風車の回転速度を制御する回転速度制御手段と、同期発電機から出力される有効電力を制御する第１の有効電力制御手段と、により制御され、逆変換器は、同期発電機から出力される有効電力および逆変換器から出力される有効電力の検出値に応じて逆変換器から電力系統へ出力される有効電力を制御する第２の有効電力制御手段により制御され、前記回転速度制御手段から出力される指令は前記第１の有効電力制御手段に入力され、前記順変換器は前記第１の有効電力制御手段の出力信号に応じて制御される電力変換器の制御方法にある。
【０００７】
【発明の実施の形態】
以下、本発明の実施例を図面に基づいて説明する。
【０００８】
（実施例１）
図１は本実施例の全体構成を示す。図１に示すように、同期発電機２の回転子が風車１の軸に接続しており、風のエネルギーで風車１が回転すると、同期発電機２が風車１の回転速度に応じて可変周波数の交流電力を発生する。本実施例の同期発電機２の定格出力は１０ｋＷ〜６００ｋＷ程度である。同期発電機２の固定子には順変換器３が接続しており、同期発電機２で発生する周波数可変の交流電力を順変換器３によって直流電力に変換する。順変換器３は二次電池４を介して逆変換器５に直流で接続している。二次電池４には、鉛蓄電池，ニッケルカドミニウム電池，ニッケル水素電池，リチウムイオン電池などを適用できる。
【０００９】
逆変換器５は順変換器３や二次電池４が供給する直流電力を、固定周波数の交流電力に変換する。逆変換器５は系統連系用変圧器６を介して、固定周波数の交流電力を電力系統に供給する。同期発電機２と順変換器３との間には、電圧検出器７と電流検出器８とが設置してあり、電圧検出器７で同期発電機２の端子電圧を、電流検出器８で同期発電機２の固定子に流れる電流を検出する。検出した電圧，電流値を３相／２相変換器１７で有効分と無効分との２軸成分に変換する。
【００１０】
有効電力検出器９は３相／２相変換器１７の出力する２軸成分の信号に基づいて同期発電機２が出力する有効電力を検出し、無効電力検出器１０は３相／２相変換器１７が出力する２軸成分の信号に基づいて、同期発電機２が出力する無効電力を検出する。
【００１１】
回転速度検出器１１は３相／２相変換器１７が出力する２軸成分の信号に基づいて風車１の回転速度を検出する。風車１の回転速度と回転速度指令との偏差を回転速度制御器１２に入力する。回転速度制御器１２の出力が順変換器３への有効電力指令となる。回転速度制御器１２は例えば比例積分制御系によって構成される。
【００１２】
風車１の回転速度が回転速度指令よりも大きい場合には回転速度制御器１２の出力が大きくなり、順変換器３への有効電力指令を大きくして、同期発電機２の出力する有効電力を大きくする。この結果、風が風車１に与える機械的入力より、同期発電機２が出力する有効電力が大きくなると入力が不足するが、入力の不足分は風車１のブレードに蓄えられた慣性エネルギーで補うため、風車１の回転速度が低下し、回転速度指令に追従する。
【００１３】
逆に風車１の回転速度が回転速度指令よりも小さい場合には回転速度制御器１２の出力が小さくなって、順変換器３への有効電力指令が小さくなり、同期発電機２が出力する有効電力が小さくなる。この結果、風が風車１に与える機械的入力よりも同期発電機２の出力する有効電力が小さくなり入力が余剰になるが、入力の余剰分は風車１のブレードに慣性エネルギーとして蓄えられることになって、風車１の回転速度が上昇し、回転速度指令に追従する。
【００１４】
有効電力制御器１３は、回転速度制御器１２の出力する有効電力指令と有効電力検出器９の検出する有効電力検出値との偏差を入力して、順変換器３への電流指令の有効分を出力する。無効電力制御器１４は、外部から与えられる無効電力指令と、無効電力検出器１０が出力する無効電力検出値との偏差を入力して、順変換器３への電流指令の無効分を出力する。有効電力制御器１３と無効電力制御器１４とはいずれも例えば比例積分制御系によって構成され、有効電力指令と有効電力検出値との偏差及び無効電力指令と無効電力検出値との偏差とが零になるように順変換器３への電流指令を決定する。
【００１５】
電流制御器１５は、３相／２相変換器１７が出力する２軸成分の電流検出値と、有効電力制御器１３が出力する順変換器３への電流指令の有効分と、無効電力制御器１４が出力する順変換器３への電流指令の無効分とを入力し、順変換器３への出力電圧指令を出力する。電流制御器１５は例えば比例積分制御系によって構成され、電流検出値と電流指令の偏差が零になるように順変換器３への出力電圧指令を決定する。電流制御器１５が出力する順変換器３への出力電圧指令は２軸成分の電圧指令であるので、２相／３相変換器１８によって３相の電圧指令に変換する。
【００１６】
パルス発生器１６は、２相／３相変換器１８が出力する順変換器３への３相出力電圧指令を入力して、ＰＷＭ（Pulse Width Modulation）によって順変換器３へのゲートパルス信号を出力する。順変換器３はゲートパルス信号を受け、パワーＭＯＳＦＥＴやＩＧＢＴ等の電力半導体スイッチング素子を高速にスイッチングさせて、指令に応じた電圧を出力する。
【００１７】
逆変換器５と系統連系用変圧器６との間には電圧検出器２３と電流検出器２４が設置し、電圧検出器２３で系統電圧を、電流検出器２４で系統へ流れる電流を検出する。検出した電圧，電流値を３相／２相変換器３１で有効分と無効分の２軸成分に変換する。
【００１８】
有効電力検出器２５は、３相／２相変換器３１が出力する２軸成分の信号に基づいて逆変換器５が系統側へ出力する有効電力を検出し、無効電力検出器２６は、３相／２相変換器３１が出力する２軸成分の信号に基づいて逆変換器５が系統側へ出力する無効電力を検出する。
【００１９】
有効電力制御器２７は、逆変換器５への有効電力指令と有効電力検出器２５の検出する有効電力検出値との偏差を入力し、逆変換器５への電流指令の有効分を出力する。無効電力制御器２８は、外部より与えられる無効電力指令と無効電力検出器２６が出力する無効電力検出値の偏差を入力し、逆変換器５への電流指令の無効分を出力する。有効電力制御器２７と無効電力制御器２８とはいずれも例えば比例積分制御系によって構成され、有効電力指令と有効電力検出値との偏差及び無効電力指令と無効電力検出値との偏差が零になるように逆変換器５への電流指令を決定する。
【００２０】
有効電力制御器２７へ入力する有効電力指令は、有効電力検出器９が出力する有効電力検出値と二次電池４の残容量とから決定する。二次電池４の残容量は、残容量検出器２０で二次電池４に流れる電流の電流検出器１９の出力を積算して求める。有効電力検出器９と残容量制御器２２との間に配置したフィルタ２１は、有効電力検出器９の出力から変動分を除去する高周波成分除去フィルタである。
【００２１】
二次電池４の残容量検出値が予め定めた一定範囲内である場合には、残容量制御器２２はフィルタ２１の出力を有効電力制御器２７への有効電力指令とする。このようにすることで、同期発電機２の出力する有効電力に含まれる変動成分は二次電池４が充放電することで補償されるので、逆変換器５が系統へ出力する有効電力は、同期発電機２が出力する有効電力から変動成分の除去されたものとなり、系統電圧や系統周波数に影響を与えない。
【００２２】
一方、二次電池４の残容量検出値が予め定めた一定範囲を超える場合には、残容量制御器２２は有効電力制御器２７への有効電力指令を調整する。これは二次電池４の残容量を適切な範囲に制御して運用しないと二次電池４の劣化等を招き、その寿命が低下するためである。したがって、残容量制御器２２は二次電池４の残容量を監視しながら、二次電池４の残容量が予め定めた一定範囲内に入るように制御する機能を備える。
【００２３】
電流制御器２９への入力は、３相／２相変換器３１が出力する２軸成分の電流検出値と、有効電力制御器２７が出力する逆変換器５への電流指令の有効分と、無効電力制御器２８が出力する逆変換器５への電流指令の無効分とである。電流制御器２９は逆変換器５への出力電圧指令を出力する。電流制御器２９は例えば比例積分制御系によって構成され、電流検出値と電流指令との偏差が零になるように逆変換器５への出力電圧指令を決定する。電流制御器２９の出力する逆変換器５への出力電圧指令は２軸成分の電圧指令であるので、２相／３相変換器３２によって３相の電圧指令に変換する。
【００２４】
パルス発生器３０は、２相／３相変換器３２の出力する逆変換器５への３相出力電圧指令に基づいて、ＰＷＭ（Pulse Width Modulation）によって逆変換器５へのゲートパルス信号を出力する。逆変換器５はゲートパルス信号を受け、パワーＭＯＳＦＥＴやＩＧＢＴ等の電力半導体スイッチング素子を高速にスイッチングさせて、指令に応じた電圧を出力する。
【００２５】
本実施例の風力発電装置では、以上のような制御系の構成によって、同期発電機２が出力する有効電力に変動成分が含まれていても、その変動成分を二次電池４で補償することで、逆変換器５が電力系統に出力する有効電力からは変動成分が除去され、系統電圧や系統周波数に影響を与えない。
【００２６】
図２に本実施例の同期発電機２の出力と、二次電池４の出力と、逆変換器５の出力との関係を示す。図２に示すように、風速の変動等で同期発電機２の出力に高周波変動成分が加わっている場合を説明する。この場合、有効電力検出器９はその高周波変動成分の乗った発電機出力を検出する。検出した発電機出力はフィルタ２１によって変動成分が除去される。ここで、二次電池４の残容量が適切な範囲であれば、フィルタ２１の出力が逆変換器５への有効電力指令となるので、図２に示すように逆変換器５の出力は同期発電機２の出力から高周波変動成分が除去されたものになる。二次電池４の出力は同期発電機２と逆変換器５の出力の差分であり、二次電池４が充放電して高周波変動成分を吸収する。
【００２７】
図３はフィルタ２１の時定数を図２より長くした場合である。フィルタ２１の時定数をこのように長くすると低い周波数成分の変動も二次電池４で吸収できる。フィルタ２１の時定数は二次電池４による変動補償を継続する時間を考慮して決定すればよい。通常はこの時間を５分から６０分程度に設定すればよい。この範囲に設定すると、仮に風車が急停止して同期発電機２の出力が零になっても、逆変換器５への有効電力指令が５分から６０分のオーダで零に近づいていくので、逆変換器５が電力系統に出力する有効電力も二次電池４が補償することによって５分から６０分のオーダでゆっくり変化する。そのため、系統電圧や系統周波数に影響を与えない。なお、このとき二次電池４の容量は、風力発電装置の定格出力を５分から６０分間出力できる容量以上が必要である。
【００２８】
次に、本実施例での二次電池４の残容量と出力との関係を説明する。二次電池４の残容量が予め定めた一定範囲内である場合は、同期発電機２が出力する有効電力から変動成分の除去したものが逆変換器５への有効電力指令になるので、二次電池４から変動成分を補償するように電力を出力する。一方、二次電池４の残容量が予め定めた一定範囲を超える場合には、残容量制御器２２によって逆変換器５への有効電力指令の調整を行うために、二次電池４の出力は単純に変動成分を補償するだけではなくなる。
【００２９】
図４（Ａ）から図４（Ｃ）に二次電池４の残容量が予め定めた残容量範囲を下回った場合の動作を表す。図４（Ａ）は残容量検出器２０の出力を、図４（Ｂ）は残容量制御器２２の出力を、図４（Ｃ）は有効電力制御器２７の制御によって二次電池４に充放電される出力を表す。二次電池４の残容量が図４（Ａ）に示すように残容量範囲の下限値を下回ると、残容量制御器２２は図４（Ｂ）に示すように逆変換器５への有効電力指令を減少させる。これに伴って二次電池４の出力が図４（Ｃ）に示すように減少し、二次電池４が放電状態から充電状態に移行すると二次電池４の残容量が図４（Ａ）に示すように増加し始める。
【００３０】
図５（Ａ）から図５（Ｃ）に二次電池４の残容量が予め定めた残容量範囲を上回った場合の動作を表す。図５（Ａ）は残容量検出器２０の出力を、図５（Ｂ）は残容量制御器２２の出力を、図５（Ｃ）は有効電力制御器２７の制御によって二次電池４に充放電される出力を表す。二次電池４の残容量が図５（Ａ）に示すように残容量範囲の上限値を上回ると、残容量制御器２２は図５（Ｂ）に示すように逆変換器５への有効電力指令を増加させる。これに伴って二次電池４の出力が図５（Ｃ）に示すように増加し、二次電池４が充電状態から放電状態に移行し、二次電池４の残容量が図５（Ａ）に示すように減少し始める。以上のように、二次電池４の残容量が予め定めた一定範囲を超える場合には、残容量制御器２２によって二次電池４の残容量が予め定めた一定範囲内に収まるように制御される。この結果、二次電池４の劣化を予防し、電池寿命を長くできる。
【００３１】
図６に二次電池４の端子電圧の変動分ΔＶと二次電池出力Ｐとの関係とを示す。ここで、変動分ΔＶは二次電池４の起電力からの変動分を表す。図６に示すように、二次電池４の端子電圧の変動分ΔＶが正の場合、二次電池４は充電される。二次電池４の端子電圧の変動分ΔＶが正ということは二次電池４の端子電圧が大きくなるということであり、二次電池４の端子電圧を大きくすると二次電池４を充電させる方向へ動作させることができる。逆に二次電池４の端子電圧の変動分ΔＶが負の場合、二次電池４は放電する。二次電池４の端子電圧の変動分ΔＶが負ということは二次電池４の端子電圧が小さくなるということであり、二次電池４の端子電圧を小さくすると二次電池４を放電させる方向へ動作させることができる。このように二次電池４の両端に加える電圧を制御することで二次電池４の出力を制御することも可能であり、同期発電機２が出力する有効電力の変動に応じて直流電圧を変動させることで風車の出力変動による出力電力の変動を抑制できる。
【００３２】
（実施例２）
図７に本実施例を示す。本実施例は図１から有効電力制御器１３と、無効電力制御器１４と、無効電力検出器１０とを除いた他は、実施例１と同じである。本実施例では、回転速度制御器１２の出力が順変換器３への有効電流指令となり、順変換器３への無効電流指令は外部から与える。
【００３３】
このような構成の場合でも、同期発電機２が出力する有効電力に変動成分が含まれていても、その変動成分を二次電池４で補償することで、逆変換器５が電力系統に出力する有効電力からは変動成分が除去され、系統電圧や系統周波数に影響を与えないようにできる。
【００３４】
以上のように構成した風力発電システムでは、風からブレードに入る機械的入力が急に零となった場合にも、二次電池４から電力を補い緩やかに風力発電装置の出力電力を緩やかに変化させることができる。
【００３５】
【発明の効果】
本発明の風力発電装置によれば、風のエネルギーを効率良く受け、電力系統への出力変動を抑制することが可能となる。
【図面の簡単な説明】
【図１】実施例１の風力発電装置の構成図である。
【図２】実施例１の風力発電装置の二次電池による補償動作説明図である。
【図３】フィルタ時定数を大きくした場合の実施例１の風力発電装置の二次電池による補償動作の説明図である。
【図４】実施例１の風力発電装置で二次電池残容量が残容量範囲下限を下回ったときの動作の説明図である。
【図５】実施例１の風力発電装置で二次電池残容量が残容量範囲上限を上回ったときの動作の説明図である。
【図６】実施例１の風力発電装置の二次電池の端子電圧変動分と出力の関係の説明図である。
【図７】実施例２の風力発電装置の構成図である。
【符号の説明】
１…風車、２…同期発電機、３…順変換器、４…二次電池、５…逆変換器、６…系統連系用変圧器、７，２３…電圧検出器、８，１９，２４…電流検出器、９，２５…有効電力検出器、１０，２６…無効電力検出器、１１…回転速度検出器、１２…回転速度制御器、１３，２７…有効電力制御器、１４，２８…無効電力制御器、１５，２９…電流制御器、１６，３０…パルス発生器、１７，３１…３相／２相変換器、１８，３２…２相／３相変換器、２０…残容量検出器、２１…フィルタ、２２…残容量制御器。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wind turbine generator including a secondary battery that suppresses output fluctuations of a synchronous generator driven by a windmill.
[0002]
[Prior art]
A conventional wind power generation system will be described. The wind turbine is connected to a synchronous generator, and the wind turbine rotates with wind energy. The wind turbine drives the synchronous generator, and the synchronous generator generates power. The AC power output from the synchronous generator is converted to DC power by a forward converter, and further converted to AC power of commercial frequency by an inverse converter and supplied to the power system. An example of such a prior art is disclosed in Japanese Patent Laid-Open No. 2000-345952.
[0003]
In such a conventional wind power generation system, the output power is greatly influenced by fluctuations in wind speed. Output fluctuations caused by wind speed fluctuations will change the frequency and voltage of the power system and affect the power system. Therefore, when introducing a wind power generation system, it is essential to suppress such fluctuations in output power. Become. Therefore, a method is adopted in which the angle of the blade of the windmill is changed according to the wind speed, and the output fluctuation due to the wind speed fluctuation is suppressed by pitch control that adjusts the mechanical input to the windmill. Furthermore, the output control of the synchronous generator by the forward converter is also performed.
[0004]
[Problems to be solved by the invention]
In the above prior art, in pitch control, in order to release the torque received from the wind, if the output fluctuation is suppressed particularly in the low wind speed region below the rating, there is a problem that the utilization factor of the windmill is lowered. The wind turbine has a pitch angle that allows the most efficient use of wind energy. To improve the wind turbine utilization rate, it is best to drive at the optimum angle. Fluctuation increases. Further, when the wind stops suddenly or when the windmill stops suddenly due to a mechanical trouble or the like, the blade of the windmill does not rotate and cannot generate power, so that the windmill output fluctuates.
[0005]
An object of this invention is to suppress the fluctuation | variation of output electric power, improving the utilization factor of a windmill with a wind power generation system.
[0006]
[Means for Solving the Problems]
One of the features of the present invention is a secondary battery provided between the forward converter and the reverse converter, a first active power detector that detects active power output from the synchronous generator, A second active power detector that detects active power output from the reverse converter to the power system, and the forward converter controller receives a deviation between the rotational speed command and the rotational speed of the windmill, A rotation speed controller that controls the rotation speed of the windmill; and a first active power controller that controls the active power output from the forward converter, wherein the inverse converter controller includes the first active power. A second active power controller for controlling the active power output from the inverse converter to the power system according to the detection value of the detector and the detection value of the second active power detector; The command output from is input to the first active power controller, and the forward converter In wind turbine generator is driven in response to the first output signal of the effective power controller.
Alternatively, a forward converter controller that controls the forward converter, and an inverse converter controller that controls the inverse converter, the forward converter controller includes a rotational speed command and a rotational speed of the windmill. A rotation speed controller that controls the rotation speed of the windmill, and a first active power controller that controls the active power output from the forward converter; Second active power control for controlling the active power output from the inverse converter to the power system according to the detected value of the active power output from the synchronous generator and the active power output from the inverse converter A command output from the rotational speed controller is input to the first active power controller, and the forward converter controller responds to the output signal of the first active power controller. It is in the converter control device that drives the converter.
Alternatively, the forward converter receives the deviation between the rotational speed command and the rotational speed of the windmill, and the rotational speed control means for controlling the rotational speed of the windmill and the first power for controlling the effective power output from the synchronous generator. The inverse converter is output from the inverse converter to the power system in accordance with the active power output from the synchronous generator and the detected value of the active power output from the inverse converter. Controlled by the second active power control means for controlling the active power, the command output from the rotational speed control means is input to the first active power control means, and the forward converter is the first active power control means. The power converter control method is controlled according to the output signal of the power control means.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0008]
Example 1
FIG. 1 shows the overall configuration of this embodiment. As shown in FIG. 1, the rotor of the synchronous generator 2 is connected to the shaft of the windmill 1, and when the windmill 1 is rotated by wind energy, the synchronous generator 2 has a variable frequency according to the rotational speed of the windmill 1. Generates AC power. The rated output of the synchronous generator 2 of the present embodiment is about 10 kW to 600 kW. A forward converter 3 is connected to the stator of the synchronous generator 2, and variable frequency AC power generated by the synchronous generator 2 is converted into DC power by the forward converter 3. The forward converter 3 is connected to the reverse converter 5 via a secondary battery 4 with a direct current. As the secondary battery 4, a lead storage battery, a nickel cadmium battery, a nickel hydrogen battery, a lithium ion battery, or the like can be applied.
[0009]
The reverse converter 5 converts the DC power supplied from the forward converter 3 and the secondary battery 4 into AC power having a fixed frequency. The reverse converter 5 supplies AC power of a fixed frequency to the power system via the grid interconnection transformer 6. A voltage detector 7 and a current detector 8 are installed between the synchronous generator 2 and the forward converter 3, and the terminal voltage of the synchronous generator 2 is changed with the current detector 8. The current flowing through the stator of the synchronous generator 2 is detected. The detected voltage and current values are converted into two-axis components of an effective component and an ineffective component by the three-phase / two-phase converter 17.
[0010]
The active power detector 9 detects the active power output from the synchronous generator 2 based on the two-axis component signal output from the three-phase / two-phase converter 17, and the reactive power detector 10 performs three-phase / two-phase conversion. The reactive power output from the synchronous generator 2 is detected based on the two-axis component signal output from the generator 17.
[0011]
The rotational speed detector 11 detects the rotational speed of the windmill 1 based on the two-axis component signal output from the three-phase / two-phase converter 17. The deviation between the rotational speed of the windmill 1 and the rotational speed command is input to the rotational speed controller 12. The output of the rotation speed controller 12 becomes an active power command to the forward converter 3. The rotational speed controller 12 is configured by, for example, a proportional-integral control system.
[0012]
When the rotational speed of the windmill 1 is greater than the rotational speed command, the output of the rotational speed controller 12 increases, the active power command to the forward converter 3 is increased, and the active power output from the synchronous generator 2 is increased. Enlarge. As a result, the input becomes insufficient when the effective power output from the synchronous generator 2 becomes larger than the mechanical input given to the wind turbine 1 by the wind, but the shortage of the input is compensated by the inertia energy stored in the blade of the wind turbine 1. The rotational speed of the windmill 1 decreases and follows the rotational speed command.
[0013]
On the contrary, when the rotational speed of the windmill 1 is smaller than the rotational speed command, the output of the rotational speed controller 12 becomes small, the active power command to the forward converter 3 becomes small, and the effective output from the synchronous generator 2 becomes effective. Electric power is reduced. As a result, the effective power output from the synchronous generator 2 becomes smaller than the mechanical input that the wind gives to the windmill 1 and the input becomes surplus, but the surplus of the input is stored in the blades of the windmill 1 as inertial energy. Thus, the rotational speed of the windmill 1 increases and follows the rotational speed command.
[0014]
The active power controller 13 inputs the deviation between the active power command output from the rotational speed controller 12 and the detected active power value detected by the active power detector 9, and the effective power command for the forward converter 3 is input. Is output. The reactive power controller 14 inputs a deviation between the reactive power command given from the outside and the reactive power detection value output from the reactive power detector 10, and outputs the reactive component of the current command to the forward converter 3. . Both the active power controller 13 and the reactive power controller 14 are configured by, for example, a proportional-integral control system, and the deviation between the active power command and the active power detection value and the deviation between the reactive power command and the reactive power detection value are zero. The current command to the forward converter 3 is determined so that
[0015]
The current controller 15 is a two-axis component current detection value output from the three-phase / two-phase converter 17, an active portion of the current command to the forward converter 3 output from the active power controller 13, and reactive power control. An invalid portion of the current command to the forward converter 3 output from the converter 14 is input, and an output voltage command to the forward converter 3 is output. The current controller 15 is configured by, for example, a proportional-integral control system, and determines an output voltage command to the forward converter 3 so that the deviation between the detected current value and the current command becomes zero. Since the output voltage command to the forward converter 3 output from the current controller 15 is a voltage command of a two-axis component, it is converted into a three-phase voltage command by the two-phase / three-phase converter 18.
[0016]
The pulse generator 16 inputs a three-phase output voltage command to the forward converter 3 output from the two-phase / three-phase converter 18 and outputs a gate pulse signal to the forward converter 3 by PWM (Pulse Width Modulation). Output. The forward converter 3 receives the gate pulse signal, switches a power semiconductor switching element such as a power MOSFET or IGBT at high speed, and outputs a voltage corresponding to the command.
[0017]
A voltage detector 23 and a current detector 24 are installed between the inverse converter 5 and the grid interconnection transformer 6. The voltage detector 23 detects the system voltage and the current detector 24 detects the current flowing into the system. To do. The detected voltage and current values are converted into two-axis components by the three-phase / two-phase converter 31 for the effective part and the invalid part.
[0018]
The active power detector 25 detects the active power output from the inverse converter 5 to the system side based on the biaxial component signal output from the three-phase / two-phase converter 31, and the reactive power detector 26 includes 3 Based on the biaxial component signal output from the phase / 2-phase converter 31, the reactive power output from the inverse converter 5 to the system side is detected.
[0019]
The active power controller 27 inputs the deviation between the active power command to the inverse converter 5 and the detected active power value detected by the active power detector 25, and outputs the effective amount of the current command to the inverse converter 5. . The reactive power controller 28 inputs a deviation between the reactive power command given from the outside and the reactive power detection value output from the reactive power detector 26, and outputs the reactive current command to the inverse converter 5. Both the active power controller 27 and the reactive power controller 28 are configured by, for example, a proportional-integral control system, and the deviation between the active power command and the active power detection value and the deviation between the reactive power command and the reactive power detection value are zero. The current command to the inverse converter 5 is determined so that
[0020]
The active power command input to the active power controller 27 is determined from the active power detection value output from the active power detector 9 and the remaining capacity of the secondary battery 4. The remaining capacity of the secondary battery 4 is obtained by integrating the output of the current detector 19 of the current flowing through the secondary battery 4 by the remaining capacity detector 20. The filter 21 disposed between the active power detector 9 and the remaining capacity controller 22 is a high-frequency component removal filter that removes fluctuations from the output of the active power detector 9.
[0021]
When the detected remaining capacity value of the secondary battery 4 is within a predetermined range, the remaining capacity controller 22 uses the output of the filter 21 as an active power command to the active power controller 27. By doing so, since the fluctuation component included in the active power output from the synchronous generator 2 is compensated by charging / discharging of the secondary battery 4, the active power output to the system by the inverse converter 5 is The fluctuation component is removed from the active power output from the synchronous generator 2, and the system voltage and system frequency are not affected.
[0022]
On the other hand, when the remaining capacity detection value of the secondary battery 4 exceeds a predetermined range, the remaining capacity controller 22 adjusts the active power command to the active power controller 27. This is because if the remaining capacity of the secondary battery 4 is not controlled and operated within an appropriate range, the secondary battery 4 is deteriorated and its life is shortened. Therefore, the remaining capacity controller 22 has a function of controlling the remaining capacity of the secondary battery 4 to be within a predetermined range while monitoring the remaining capacity of the secondary battery 4.
[0023]
The input to the current controller 29 includes the current detection value of the biaxial component output from the three-phase / two-phase converter 31, the effective amount of the current command to the inverse converter 5 output from the active power controller 27, and The reactive power controller 28 outputs the current command to the inverse converter 5 that is ineffective. The current controller 29 outputs an output voltage command to the inverse converter 5. The current controller 29 is configured by, for example, a proportional-integral control system, and determines an output voltage command to the inverse converter 5 so that the deviation between the detected current value and the current command becomes zero. Since the output voltage command to the inverse converter 5 output from the current controller 29 is a voltage command of a two-axis component, the two-phase / three-phase converter 32 converts it to a three-phase voltage command.
[0024]
The pulse generator 30 outputs a gate pulse signal to the inverse converter 5 by PWM (Pulse Width Modulation) based on the three-phase output voltage command to the inverse converter 5 output from the two-phase / three-phase converter 32. To do. The inverse converter 5 receives a gate pulse signal, switches a power semiconductor switching element such as a power MOSFET or IGBT at high speed, and outputs a voltage corresponding to the command.
[0025]
In the wind power generator according to the present embodiment, even if a fluctuation component is included in the active power output from the synchronous generator 2 by the configuration of the control system as described above, the fluctuation component is compensated by the secondary battery 4. Thus, the fluctuation component is removed from the active power output from the inverse converter 5 to the power system, and the system voltage and the system frequency are not affected.
[0026]
FIG. 2 shows the relationship among the output of the synchronous generator 2 of the present embodiment, the output of the secondary battery 4, and the output of the inverse converter 5. As shown in FIG. 2, a case where a high-frequency fluctuation component is added to the output of the synchronous generator 2 due to fluctuations in wind speed and the like will be described. In this case, the active power detector 9 detects the generator output carrying the high-frequency fluctuation component. A fluctuation component is removed from the detected generator output by the filter 21. Here, if the remaining capacity of the secondary battery 4 is in an appropriate range, the output of the filter 21 becomes an active power command to the inverse converter 5, so that the output of the inverse converter 5 is synchronized as shown in FIG. The high frequency fluctuation component is removed from the output of the generator 2. The output of the secondary battery 4 is the difference between the outputs of the synchronous generator 2 and the inverse converter 5, and the secondary battery 4 is charged and discharged to absorb the high frequency fluctuation component.
[0027]
FIG. 3 shows a case where the time constant of the filter 21 is longer than that in FIG. When the time constant of the filter 21 is increased in this manner, the fluctuation of the low frequency component can be absorbed by the secondary battery 4. The time constant of the filter 21 may be determined in consideration of the time during which fluctuation compensation by the secondary battery 4 is continued. Normally, this time may be set to about 5 to 60 minutes. If this range is set, even if the windmill stops suddenly and the output of the synchronous generator 2 becomes zero, the active power command to the inverse converter 5 approaches zero on the order of 5 to 60 minutes. The effective power output from the inverter 5 to the power system also slowly changes in the order of 5 to 60 minutes as the secondary battery 4 compensates. Therefore, the system voltage and system frequency are not affected. In addition, the capacity | capacitance of the secondary battery 4 at this time needs more than the capacity | capacitance which can output the rated output of a wind power generator for 5 to 60 minutes.
[0028]
Next, the relationship between the remaining capacity of the secondary battery 4 and the output in this embodiment will be described. If the remaining capacity of the secondary battery 4 is within a predetermined range, the active power output from the synchronous generator 2 is the active power command to the inverter 5 because the fluctuation component is removed from the active power. Electric power is output from the secondary battery 4 so as to compensate the fluctuation component. On the other hand, when the remaining capacity of the secondary battery 4 exceeds a predetermined range, the output of the secondary battery 4 is adjusted to adjust the active power command to the inverse converter 5 by the remaining capacity controller 22. It is no longer simply compensating for the fluctuation component.
[0029]
FIG. 4A to FIG. 4C show an operation when the remaining capacity of the secondary battery 4 falls below a predetermined remaining capacity range. 4A shows the output of the remaining capacity detector 20, FIG. 4B shows the output of the remaining capacity controller 22, and FIG. 4C shows that the secondary battery 4 is charged under the control of the active power controller 27. Represents the output to be discharged. When the remaining capacity of the secondary battery 4 falls below the lower limit value of the remaining capacity range as shown in FIG. 4 (A), the remaining capacity controller 22 causes the active power to the inverse converter 5 as shown in FIG. 4 (B). Decrease command. Along with this, the output of the secondary battery 4 decreases as shown in FIG. 4C, and when the secondary battery 4 shifts from the discharged state to the charged state, the remaining capacity of the secondary battery 4 is shown in FIG. Start to increase as shown.
[0030]
FIG. 5A to FIG. 5C show an operation when the remaining capacity of the secondary battery 4 exceeds a predetermined remaining capacity range. FIG. 5A shows the output of the remaining capacity detector 20, FIG. 5B shows the output of the remaining capacity controller 22, and FIG. 5C shows that the secondary battery 4 is charged under the control of the active power controller 27. Represents the output to be discharged. When the remaining capacity of the secondary battery 4 exceeds the upper limit value of the remaining capacity range as shown in FIG. 5 (A), the remaining capacity controller 22 causes the active power to the inverse converter 5 as shown in FIG. 5 (B). Increase command. Along with this, the output of the secondary battery 4 increases as shown in FIG. 5C, the secondary battery 4 shifts from the charged state to the discharged state, and the remaining capacity of the secondary battery 4 is as shown in FIG. Start to decrease as shown. As described above, when the remaining capacity of the secondary battery 4 exceeds a predetermined fixed range, the remaining capacity controller 22 controls the remaining capacity of the secondary battery 4 to be within a predetermined fixed range. The As a result, deterioration of the secondary battery 4 can be prevented and the battery life can be extended.
[0031]
FIG. 6 shows the relationship between the terminal voltage variation ΔV of the secondary battery 4 and the secondary battery output P. Here, the variation ΔV represents the variation from the electromotive force of the secondary battery 4. As shown in FIG. 6, when the variation ΔV of the terminal voltage of the secondary battery 4 is positive, the secondary battery 4 is charged. When the variation ΔV of the terminal voltage of the secondary battery 4 is positive, the terminal voltage of the secondary battery 4 is increased. When the terminal voltage of the secondary battery 4 is increased, the secondary battery 4 is charged. It can be operated. Conversely, when the variation ΔV of the terminal voltage of the secondary battery 4 is negative, the secondary battery 4 is discharged. When the variation ΔV of the terminal voltage of the secondary battery 4 is negative, the terminal voltage of the secondary battery 4 is reduced. When the terminal voltage of the secondary battery 4 is reduced, the secondary battery 4 is discharged. It can be operated. In this way, it is also possible to control the output of the secondary battery 4 by controlling the voltage applied to both ends of the secondary battery 4, and the DC voltage varies according to the variation of the active power output from the synchronous generator 2. By doing so, fluctuations in output power due to fluctuations in the output of the windmill can be suppressed.
[0032]
(Example 2)
FIG. 7 shows this embodiment. The present embodiment is the same as the first embodiment except that the active power controller 13, the reactive power controller 14, and the reactive power detector 10 are omitted from FIG. In the present embodiment, the output of the rotation speed controller 12 becomes an active current command to the forward converter 3, and the reactive current command to the forward converter 3 is given from the outside.
[0033]
Even in such a configuration, even if the active power output from the synchronous generator 2 includes a fluctuation component, the reverse converter 5 outputs the fluctuation component to the power system by compensating the fluctuation component with the secondary battery 4. Thus, the fluctuation component is removed from the active power, and the system voltage and system frequency can be prevented from being affected.
[0034]
In the wind power generation system configured as described above, even when the mechanical input entering the blade from the wind suddenly becomes zero, the power from the secondary battery 4 is supplemented to gradually change the output power of the wind power generator. Can be made.
[0035]
【The invention's effect】
According to the wind power generator of the present invention, it is possible to efficiently receive wind energy and suppress output fluctuations to the power system.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a wind turbine generator according to a first embodiment.
FIG. 2 is an explanatory diagram of compensation operation by the secondary battery of the wind turbine generator of the first embodiment.
FIG. 3 is an explanatory diagram of compensation operation by the secondary battery of the wind turbine generator of Example 1 when the filter time constant is increased.
4 is an explanatory diagram of an operation when the remaining capacity of the secondary battery is lower than the lower limit of the remaining capacity range in the wind power generator of Example 1. FIG.
FIG. 5 is an explanatory diagram of an operation when the remaining capacity of the secondary battery exceeds the remaining capacity range upper limit in the wind turbine generator of Example 1.
6 is an explanatory diagram of a relationship between a terminal voltage fluctuation amount and an output of a secondary battery of the wind turbine generator of Example 1. FIG.
7 is a configuration diagram of a wind turbine generator according to Embodiment 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Windmill, 2 ... Synchronous generator, 3 ... Forward converter, 4 ... Secondary battery, 5 ... Reverse converter, 6 ... Transformer for grid connection, 7, 23 ... Voltage detector, 8, 19, 24 ... Current detector, 9, 25 ... Active power detector, 10,26 ... Reactive power detector, 11 ... Rotational speed detector, 12 ... Rotational speed controller, 13,27 ... Active power controller, 14,28 ... Reactive power controller, 15, 29 ... Current controller, 16, 30 ... Pulse generator, 17, 31 ... 3-phase / 2-phase converter, 18, 32 ... 2-phase / 3-phase converter, 20 ... Remaining capacity detection 21, filter, 22, remaining capacity controller.

Claims

A synchronous generator with a rotor connected to the shaft of the windmill;
A forward converter connected to the stator of the synchronous generator;
An inverse converter connected to the forward converter and connected to the power system;
A forward converter controller for controlling the forward converter;
An inverse converter controller for controlling the inverse converter;
The forward converter converts variable frequency generated power generated by the synchronous generator into DC power,
In the wind turbine generator that converts the DC power into AC power of a fixed frequency, the reverse converter,
A secondary battery provided between the forward converter and the reverse converter;
A first active power detector for detecting active power output from the synchronous generator;
A second active power detector for detecting active power output from the inverse converter to the power system,
The forward converter controller is
A rotational speed controller for controlling the rotational speed of the windmill, by inputting a deviation between the rotational speed command and the rotational speed of the windmill;
A first active power controller for controlling the active power output from the synchronous generator,
The inverse converter controller is
A second active power controller that controls the active power output from the inverse converter to the power system according to the detection value of the first active power detector and the detection value of the second active power detector ;
A command output from the rotation speed controller is input to the first active power controller, and the forward converter is driven in accordance with an output signal of the first active power controller. Wind power generator.

In claim 1,
The inverse converter controller is
A wind turbine generator comprising: a filter that removes a fluctuation component of a detection value of the first active power detector, and using an output of the filter as an active power command value of the second active power controller.

In claim 2,
The remaining capacity detector for detecting the remaining capacity of the secondary battery and the active power command of the second active power controller are adjusted in a direction in which the detected value of the remaining capacity detector falls within a predetermined range. And a wind power generator characterized by comprising operating means.

A synchronous generator with a rotor connected to the shaft of the windmill;
A forward converter connected to the stator of the synchronous generator;
An inverse converter connected to the forward converter and connected to the power system;
In the converter control device for controlling the forward converter and the reverse converter of a wind power generator comprising a secondary battery provided between the forward converter and the reverse converter,
A forward converter controller for controlling the forward converter;
An inverse converter controller for controlling the inverse converter;
The forward converter controller is
A rotational speed controller for controlling the rotational speed of the windmill, by inputting a deviation between the rotational speed command and the rotational speed of the windmill;
A first active power controller for controlling the active power output from the synchronous generator,
The inverse converter controller is
A second active power controller that controls the active power output from the inverse converter to the power system in accordance with the detected value of the active power output from the synchronous generator and the active power output from the inverse converter With
A command output from the rotation speed controller is input to the first active power controller, and the forward converter controller drives the forward converter in accordance with an output signal of the first active power controller. A converter control device characterized by:

In claim 4,
The inverse converter controller includes a filter that removes a fluctuation component of the active power output from the synchronous generator, and the output of the filter is used as an active power command value of the second active power controller. A characteristic converter control device.

In claim 5,
When the remaining capacity of the secondary battery is outside a predetermined range, the active power command value of the second active power controller is controlled in a direction in which the remaining capacity of the secondary battery falls within the predetermined range. A converter control device comprising operating means.

A synchronous generator with a rotor connected to the shaft of the windmill;
A forward converter connected to the stator of the synchronous generator;
An inverse converter connected to the forward converter and connected to the power system;
In the forward converter and the control method of the inverse converter of a wind turbine generator comprising a secondary battery provided between the forward converter and the inverse converter,
The forward converter is
A rotational speed control means for inputting a deviation between the rotational speed command and the rotational speed of the windmill and controlling the rotational speed of the windmill;
Controlled by the first active power control means for controlling the active power output from the synchronous generator,
The inverse converter is
Second active power control means for controlling the active power output from the inverse converter to the power system in accordance with the detected value of the active power output from the synchronous generator and the active power output from the inverse converter Controlled by
A command output from the rotation speed control means is input to the first active power control means, and the forward converter is controlled in accordance with an output signal of the first active power control means. Control method of power converter.

In claim 7,
The inverse converter is
A method of controlling a power converter, wherein an output of a filter that removes a fluctuation component of active power output from the synchronous generator is used as an active power command value of the second active power control means.

In claim 8,
When the remaining capacity of the secondary battery is outside a predetermined range, the active power command value of the second active power control means is adjusted in a direction in which the remaining capacity of the secondary battery falls within the predetermined range. A method for controlling a power converter.