JP4605942B2 - Cogeneration system operation method - Google Patents

Description

ここで、Ｓ（０）は初期蓄熱量を示している。Ｆは定格発電量を、ｋは熱電比をそれぞれ示している。
また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。そして、Ｈは、余剰電力を電熱変換手段で熱に変換した変換熱量で、Ｆ＞ｅ（ｔ）の分を積算するものであり、下記（２）式で表される。
【数１６】

但し、ｅ（ｔ）＜Ｆであれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆであれば、Ｅ（ｔ）＝Ｆ
ここで、Ｅ（ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量であり、ｅ（ｔ）は、予め特定された電力需要の経時的変化を示す関数である。
ＰＥ１＝ＧＩ・α＋ＢＥ・β……（３）
ここで、ＧＩは運転開始時刻ａから運転終了時刻ｂまでの熱電併給装置の運転に要する燃料供給量であり、次式（４）で表される。αは燃料の一次エネルギーへの換算値である。
【数１７】

ここで、ＧＩ（ｔ）は、使用する熱電併給装置によって特定される燃料供給量である。
ＢＥは、１周期Ｔとなる所定時間Ｔ内での不足分の電力の投入量であり、次式（５）で表される。βは電力の一次エネルギーへの換算値である。
【数１８】

ここで、ＧＰは、熱電併給装置の発電量であり、次式（６）で表される。
【数１９】

但し、ｅ（ｔ）＜Ｆであれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆであれば、Ｅ（ｔ）＝Ｆ
【０００９】
また、請求項３に係る発明のコージェネレーションシステムの運転方法は、前述のような目的を達成するために、
負荷電力が定格発電量より少ない場合負荷に合わせて運転することができる電力と熱とを発生する熱電併給装置と、
前記熱電併給装置で発生した熱を貯める蓄熱タンクと、
所定時間を１周期として、その１周期および次の１周期それぞれ内の熱需要および電力需要それぞれの経時的変化を予め特定する需要変化特定手段と、
不足分の電力を投入可能な買電手段とを備え、
前記１周期内での熱需要分に相当する量の熱を前記熱電併給装置により前記１周期内で発生させて消費する第１の状態、および、負荷電力の多い時間帯で運転して余剰となった熱を次の周期で消費する第２の状態それぞれを想定し、前記１周期を設定時間間隔ごとに分割した運転開始時刻を順次入力し、前記蓄熱タンク内の蓄熱量が０以上になるようにして、全体の一次エネルギーの換算値が最小となる最適運転状態を前記第１および第２の状態の全体から求め、求められた最適運転状態の運転開始時刻とその運転開始時刻から導かれる運転終了時刻とによって、前記熱電併給装置を定格発電量で運転するとともに電力需要が定格発電量よりも小さいときには電力需要の変化に追従させて運転することを特徴としている。
また、請求項４に係る発明のコージェネレーションシステムの運転方法は、前述のような目的を達成するために、
請求項３に記載のコージェネレーションシステムの運転方法において、
所定時間を１周期Ｔとして、その１周期Ｔおよび次の１周期Ｔそれぞれ内の熱需要および電力需要それぞれの経時的変化を予め特定する需要変化特定手段を備え、
前記１周期Ｔ内での熱需要分に相当する量の熱を前記熱電併給装置により前記１周期Ｔ内で発生させて消費する第１の状態、および、負荷電力の多い時間帯で運転して余剰となった熱を次の周期で消費する第２の状態それぞれを想定し、前記１周期Ｔを設定時間間隔ごとに分割した運転開始時刻ａを順次入力し、前記蓄熱タンク内の蓄熱量の変動値Ｓ（ｔ）が常に下記条件式（７）を満たすとともに、下記一次エネルギーの換算値ＰＥ１［式（３）］が最小となる最適運転状態を前記第１および第２の状態の全体から求め、求められた最適運転状態の運転開始時刻ａとその運転開始時刻ａから導かれる運転終了時刻ｂとによって、前記熱電併給装置を定格発電量で運転するとともに電力需要が定格発電量よりも小さいときには電力需要の変化に追従させて運転することを特徴としている。
【数２０】

ここで、Ｓ（０）は初期蓄熱量を示し、Ｅ（ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量である。Ｂ［Ｅ（ｔ）］は、電力量Ｅ（ｔ）における熱電併給装置の発生熱量を示している。
また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。
ＰＥ１＝ＧＩ・α＋ＢＥ・β……（３）
ここで、ＧＩは運転開始時刻ａから運転終了時刻ｂまでの熱電併給装置の運転に要する燃料供給量であり、次式（４ａ）で表される。αは燃料の一次エネルギーへの換算値である。
【数２１】

ここで、ＧＩ（ｔ）は、負荷電力が定格発電量よりも少ない運転において使用する熱電併給装置によって特定される燃料供給量である。
ＢＥは、１周期Ｔとなる所定時間Ｔ内での不足分の電力の投入量であり、次式（５）で表される。βは電力の一次エネルギーへの換算値である。
【数２２】

ここで、ＧＰは、熱電併給装置の発電量であり、次式（６）で表される。
【数２３】

但し、ｅ（ｔ）＜Ｆであれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆであれば、Ｅ（ｔ）＝Ｆ
上記（５）および（６）式において、ｅ（ｔ）は、予め特定された電力需要の経時的変化を示す関数である。
【００１０】
また、請求項５に係る発明のコージェネレーションシステムの運転方法は、前述のような目的を達成するために、
複数段に設定した発電量で運転して設定発電量の電力と熱とを発生する熱電併給装置と、
前記熱電併給装置で発生した熱を貯める蓄熱タンクと、
所定時間を１周期として、その１周期および次の１周期それぞれ内の熱需要および電力需要それぞれの経時的変化を予め特定する需要変化特定手段と、
不足分の電力を投入可能な買電手段とを備え、
前記１周期内での熱需要分に相当する量の熱を前記熱電併給装置により前記１周期内で発生させて消費する第１の状態、および、負荷電力の多い時間帯で運転して余剰となった熱を次の周期で消費する第２の状態それぞれを想定し、前記１周期を電気負荷に合わせて、複数段に設定した発電量で運転し、その複数段の発電量が変わる時刻を複数段の設定発電量の運転状態それぞれに順次入力し、前記蓄熱タンク内の蓄熱量が０以上になるようにして、全体の一次エネルギーの換算値が最小となる最適運転状態を前記第１および第２の状態の全体から求め、求められた最適運転状態の運転開始時刻によって、前記熱電併給装置を複数段の設定発電量で運転することを特徴としている。
また、請求項６に係る発明のコージェネレーションシステムの運転方法は、前述のような目的を達成するために、
請求項５に記載のコージェネレーションシステムの運転方法において、
前記１周期Ｔ内での熱需要分に相当する量の熱を前記熱電併給装置により前記１周期Ｔ内で発生させて消費する第１の状態、および、負荷電力の多い時間帯で運転して余剰となった熱を次の周期で消費する第２の状態それぞれを想定し、前記１周期Ｔを電気負荷に合わせて、複数段に設定した発電量で運転し、その複数段の発電量が変わる時刻をａ₁ ，…，ａ_n-1 （ｎは正の整数）として複数段の設定発電量の運転状態それぞれに順次入力し、前記蓄熱タンク内の蓄熱量の変動値Ｓ’（ｔ）が常に下記条件式（８）を満たすとともに、下記一次エネルギーの換算値ＰＥ１’［式（９）］が最小となる最適運転状態を前記第１および第２の状態の全体から求め、求められた最適運転状態の運転開始時刻ａ₁ ，…，ａ_n-1 によって、前記熱電併給装置を複数段の設定発電量で運転することを特徴としている。
【数２４】

ここで、Ｓ’（０）は初期蓄熱量を示し、Ｆ₁ 、…、Ｆ_n は各設定発電量を、ｋ₁ 、…、ｋ_n は各設定発電量の熱電比をそれぞれ示している。Ｈ₁ 、Ｈ₂ 、…、Ｈ_n-1 は余剰電力を電熱変換手段で熱に変換した変換熱量であり、次式で示される。
【数２５】

但し、ｅ（ｔ）＜Ｆ_k であれば、Ｅ_k （ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆ_k であれば、Ｅ_k （ｔ）＝Ｆ_k
ｋは１からｎ−１までの整数である。
Ｅ_k （ｔ）は、負荷電力が各設定発電量を越える場合は各設定発電量となり、負荷電力が各設定発電量より小さい場合はその負荷電力量となる電力量である。また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。
ＰＥ１’＝ＧＩ’・α＋ＢＥ’・β……（９）
ここで、ＧＩ’は、各複数段に設定した運転の運転開始時刻ａ₁ ，…，ａ_n-1からの熱電併給装置の運転に要する総燃料供給量であり、次式（１０）で表される。ｎは正の整数であり、ＧＩ’（ｔ）は、複数段の発電に起因して運転される熱電併給装置によって特定される燃料供給量である。αは燃料の一次エネルギーへの換算値である。
【数２６】

ＢＥ’は、１周期Ｔとなる所定時間Ｔ内での不足分の電力の投入量であり、次式（１１）で表される。βは電力の一次エネルギーへの換算値である。
【数２７】

ここで、ＧＰ’は、熱電併給装置の発電量であり、次式（１２）で表される。
【数２８】

但し、ｅ（ｔ）＜Ｆ_k であれば、Ｅ_k （ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆ_k であれば、Ｅ_k （ｔ）＝Ｆ_k
上記（１１）および（１２）式において、ｅ（ｔ）は、予め特定された電力需要の経時的変化を示す関数である。
【００１１】
【作用】
請求項１および請求項２に係る発明のコージェネレーションシステムの運転方法の構成によれば、熱電併給装置を定格発電量で運転して発電し、電力需要が定格発電量よりも小さいときの電力需要を越える余剰の電力を電熱変換手段によって熱に変換し、不足分の電力を買電手段で賄うとともに、変換した熱と熱電併給装置で発生した熱によって熱需要を賄い、かつ、後で必要とする熱を蓄熱タンクに貯めて熱需要に応じることができる。このときに、例えば、１日などの１周期内にとどまらず、翌日の午前分や昼分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転する。
【００１２】
また、請求項３および請求項４に係る発明のコージェネレーションシステムの運転方法の構成によれば、電力需要が定格発電量を越えるときは熱電併給装置を定格発電量で運転して発電し、電力需要が定格発電量よりも小さいときは熱電併給装置を電力需要に追従して運転して発電し、不足分の電力を買電手段で賄うとともに熱電併給装置で発生した熱によって熱需要を賄い、かつ、後で必要とする熱を蓄熱タンクに貯めて熱需要に応じることができる。このときに、例えば、１日などの１周期内にとどまらず、翌日の午前分や昼分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転する。
【００１３】
また、請求項５および請求項６に係る発明のコージェネレーションシステムの運転方法の構成によれば、例えば、１日間など、１周期となる所定時間内において、熱電併給装置を複数段に設定した発電量で運転して発電し、不足分の電力を買電手段で賄うとともに熱電併給装置で発生した熱および電力需要が定格発電量より小さい時の電力需要を越える余剰電力を電熱変換手段により変換される熱とによって熱需要を賄い、かつ、後で必要とする熱を蓄熱タンクに貯めて熱需要に応じることができる。このときに、例えば、１日などの１周期内にとどまらず、翌日の午前分や昼分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転する。
【００１４】
【発明の実施の形態】
次に、本発明の実施例につき、図面に基づいて詳細に説明する。
図１は、コージェネレーションシステムの第１実施例を示すシステム構成図であり、１は熱電併給装置を、２は蓄熱タンクをそれぞれ示している。
【００１５】
蓄熱タンク２には、その底側から上部にわたって第１のポンプ３を備えた循環配管４が接続されている。循環配管４に熱交換器５が設けられ、熱電併給装置１と熱交換器５とにわたって、第２のポンプ６を備えた熱回収用循環配管７が接続されている。
【００１６】
この構成により、蓄熱タンク２の下部から取り出した水を熱電併給装置１からの熱によって加熱し、その加熱された蓄熱水を蓄熱タンク２に戻して蓄熱するように構成されている。
循環配管４の熱交換器５よりも下流側の箇所に電熱変換手段としての電気ヒータ８が設けられ、熱電併給装置１で発生した電力が余剰の場合に、余剰電力を熱に変換して蓄熱タンク２の下部から取り出した水を加熱し、その加熱された蓄熱水を蓄熱タンク２に蓄えることができるように構成されている。図中９は、給湯用の給湯管を示している。
【００１７】
循環配管４には、熱交換器５と直列になるように出力用循環配管１０が接続されるとともに、その出力用循環配管１０に暖房用熱交換器１１が設けられ、暖房用熱交換器１１に、第３のポンプ１２を備えた暖房用循環配管１３を介して、室内暖房機、床暖房機、浴室乾燥機などのセントラルヒーティング用の暖房装置１４が接続されている。
【００１８】
熱電併給装置１には、発電電力を取り出す電力線１５が接続され、その電力線１５に、照明装置や電気機器などの電気負荷１６が接続されている。また、電力線１５に逆潮流防止用の保護装置１７を介して商用電源線１８が接続され、発電電力で不足するときに商用電源からの電力を投入できるように買電手段１９が構成されている。
【００１９】
また、電力線１５に、スイッチ回路２０を介して電気ヒータ８が接続され、余剰電力の発生時に電気ヒータ８に通電するようになっている。この電気ヒータ８としては、二点鎖線で示すように、熱回収用循環配管７に設けるようにしても良い。図中２１はバックアップ用のガスボイラを示している。
【００２０】
熱電併給装置１およびスイッチ回路２０にはマイクロコンピュータ２２が接続されている。
マイクロコンピュータ２２には学習機能が備えられていて、図２のブロック図に示すように、需要変化特定手段２３と運転時刻入力手段２４と演算手段２５と比較手段２６と運転制御手段２７とが備えられている。
【００２１】
需要変化特定手段２３では、前述した学習機能によって記憶されているデータに基づき、図３および図４のグラフに示すように、１周期Ｔとしての１日間における前述した、照明装置や電気機器駆動のための電力需要ｅ（ｔ）、および、給湯や暖房などの熱需要ｈ（ｔ）の経時的変化を、予め特定できるように構成されている。また、表−１に、上記給湯や暖房などの熱需要ｈ（ｔ）の経時的変化の数値例を示す。なお、図３および図４は、多数の需要家の平均値をとって概略的な変化として示したものである。
【表１】

【００２２】
すなわち、前日の需要変化とか、１週間前の同じ曜日の需要変化などが順次記憶され、それらの需要変化に基づいて当日１日間および翌日１日間における熱需要ｈ（ｔ）、および、電力需要ｅ（ｔ）の経時的変化を、予め特定できるようになっているのである。
【００２３】
運転時刻入力手段２４では、１周期Ｔとしての１日間を、例えば、１分間ごとなど、設定時間間隔ごとに分割した運転開始時刻ａを順次入力するようになっている。
【００２４】
演算手段２５では、需要変化特定手段２３からの当日１日間および翌日１日間における熱需要ｈ（ｔ）、および、電力需要ｅ（ｔ）の経時的変化に基づいて、後述する条件式に運転時刻入力手段２４から運転開始時刻ａとそれから導かれる運転終了時刻ｂとを入力することにより、一次エネルギーの換算値を演算するようになっている。
【００２５】
比較手段２６では、演算手段２５から入力される一次エネルギーの換算値を記憶し、その換算値と次に入力される換算値とを比較し、小さいほうの換算値とそのときの運転開始時刻ａおよび運転終了時刻ｂを新たに記憶していき、１日間分の運転開始時刻ａの入力を終了した後に、一次エネルギーの換算値が最小であった運転開始時刻ａおよび運転終了時刻ｂを出力するようになっている。
【００２６】
運転制御手段２７では、比較手段２６からの運転開始時刻ａおよび運転終了時刻ｂに応答して、熱電併給装置１およびスイッチ回路２０に駆動信号を出力し、一次エネルギーの換算値が最小になる状態でコージェネレーションシステムを運転するようになっている。
【００２７】
次に、上記条件式について説明する。
第１実施例では、熱電併給装置１を発電効率が最も高い定格発電量(100％負荷) で運転し、電力需要ｅ（ｔ）が定格発電量よりも小さい余剰電力分を電気ヒータ８によって熱に変換するものとする。ここでの定格発電量としては、１ｋｗを例示する。この定格発電量は、例えば、０．８ｋｗなど、使用する熱電併給装置によって決まるものである。
【００２８】
先ず、１周期Ｔとしての１日間での熱需要分またはその大半に相当する量の熱を熱電併給装置１により１日間で発生させて消費する第１の状態を想定する。１日全体での必要な熱需要ｈ（ｔ）の総量Ａは、下記（１３）式
【数２９】

で求められる。また、システム全体として、熱電併給装置１の筐体や蓄熱タンク２や配管からの放熱があり、その放熱量Ｂは時間の関数として下記（１４）式で表すことができ、
【数３０】

となる。
【００２９】
これらのことから、熱電併給装置１の運転開始時刻をａ、運転終了時刻をｂと想定して運転した場合に、得られる総熱量は、余剰電力を電気ヒータ８で熱に変換した変換熱量に熱電併給装置１からの熱量を足したものになり、この総熱量が前述した熱需要ｈ（ｔ）の総量Ａと放熱量Ｂとを加算したものと等しくなる必要がある。
【００３０】
余剰電力Ｅは、図５の（ａ）の電力需要の経時的変化のグラフに示すように、電力需要ｅ（ｔ）［ｋｗ］が定格発電量１ｋｗよりも小さい運転時間（ａからｃまで）の分であり、余剰電力Ｅを電気ヒータ８によって熱に変換した変換熱量Ｈは、図５の（ｂ）の熱需要の経時的変化のグラフに示すように、
【数３１】

となる。
但し、ｅ（ｔ）＜１であれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧１であれば、Ｅ（ｔ）＝１
ここで、Ｅ（ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量である。
【００３１】
熱電併給装置１からの熱量Ｄは、定格発電量をＦ、熱電比をｋとすれば、
Ｄ＝Ｆ・Ｋ・（ｂ−ａ）
となる。いま、Ｆ＝１、ｋ＝３．２５であるとすれば、図６のグラフに示すように、
Ｄ＝3.25（ｂ−ａ）
となる。
【００３２】
熱需要を主体として常に満たすためには、熱電併給装置１の運転に伴って得られる総熱量（＝熱量Ｄ＋変換熱量Ｈ）が、図７のグラフに示すように、熱需要ｈ（ｔ）の総量Ａ相当分（斜線部分Ａで示す）と放熱量Ｂ相当分（斜線部分Ａの上部分Ｂで示す）とを加算したもの以上になる必要があり、下記（１５）式が成立する。
【数３２】

但し、ｅ（ｔ）＜１であれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧１であれば、Ｅ（ｔ）＝１
ここで、Ｅ（ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量である。
【００３３】
放熱量Ｂの関数ｅｘ（ｔ）は、蓄熱タンク２からの放熱量ＳＴ（ｔ）、配管からの放熱量ＰＬ（ｔ）と熱電併給装置１の筐体からの放熱量ＧＥ（ｔ）との総和、すなわち、
ｅｘ（ｔ）＝ＳＴ（ｔ）＋ＰＬ（ｔ）＋ＧＥ（ｔ）……（１６）
で表すことができる。
【００３４】
上記蓄熱タンク２、配管および熱電併給装置１の筐体からの放熱量ＳＴ（ｔ），ＰＬ（ｔ），ＧＥ（ｔ）それぞれは、主としてシステム構築時の規模に比例した熱容量によって決まるものであり、例えば、配管や熱電併給装置１の筐体や蓄熱タンク２を断熱材で覆うような構成を採用すれば、その放熱量を抑えることができるが、断熱材の断熱効果もシステム構築時に予め特定できるものであり、いずれにしても、配管や熱電併給装置１の筐体や蓄熱タンク２からの放熱量は、実験や計算や学習効果などによって予め特定できるものである。
【００３５】
以上のことから、蓄熱タンク２内に蓄えられている蓄熱量Ｓ（ｔ）は、次のように示すことができ、また、コージェネレーションシステムにおいて、熱需要を賄うために、蓄熱量Ｓ（ｔ）が不足しないことが条件になる。すなわち、
【数３３】

である。ここで、Ｓ（０）は初期蓄熱量を示し、例えば、当日の運転開始時刻ａ（この第１実施例では、午前１２時頃）までに必要な分を設定するなど、予め特定される電力需要と熱需要とに基づいて適宜設定されるものであり、予め特定できるものである。表−１に基づけば、初期蓄熱量は2,000［×(1/860)kW］である。
【００３６】
前述（１５）式において、熱需要ｈ（ｔ）、電力需要ｅ（ｔ）、ならびに、電力需要ｅ（ｔ）が定格発電量を越える時刻ｃそれぞれは、前述したように需要変化特定手段２３によって予め特定され、また、運転終了時刻ｂは、（１５）式の両辺を等しいとすることにより、運転開始時刻ａに基づいて特定できる。
【００３７】
これらのことから、運転開始時刻ａを想定することにより、運転開始時刻ａから運転終了時刻ｂまでの熱電併給装置１の運転に要する燃料供給量ＧＩを、次式（４）で求めることができる。
【数３４】

【００３８】
また、１日間の不足分の電力の投入量ＢＥは、次式（１８）で求めることができる。
【数３５】

ここで、ＧＰは、熱電併給装置の発電量であり、次式（６）で表される。
【数３６】

但し、ｅ（ｔ）＜Ｆであれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆであれば、Ｅ（ｔ）＝Ｆ
ここで、Ｅ（ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量である。
上記（１８）式および（６）式において、ｅ（ｔ）は、予め特定された電力需要の経時的変化を示す関数である。
【００３９】
これらの燃料供給量ＧＩ、１日間の不足分の電力の投入量ＢＥおよびシステムからの放熱量の一次エネルギーの換算値ＰＥ１を求めれば、
ＰＥ１＝ＧＩ・α＋ＢＥ・β……（３）
となる。ここで、αは燃料の一次エネルギーへの換算値、βは電力の一次エネルギーへの換算値である。ｅｘ（ｔ）は、前述したように、システムからの放熱量である。
【００４０】
更に、例えば、夕方に多量の電力需要があり、その発電効率が高く、熱電併給装置１の運転時間帯を夕方側にシフトし、蓄えた熱を翌日に消費した方が省エネルギー性を向上できる場合があることに着目し、負荷電力の多い時間帯で熱電併給装置１を運転して、余剰となった熱を次の１周期としての翌日に消費させる第２の状態を想定する。
【００４１】
このように翌日に消費することを前提とする場合には、図８の（ａ）および（ｂ）の熱需要と電力需要の経時的変化のグラフに示すように、翌日の熱需要分の約25％分を翌日に消費するように設定し、その翌日に消費する熱量分をも含めた状態で、熱電併給装置１の運転開始時刻ａと運転終了時刻ｂとを導出することになる。
【００４２】
この翌日に消費する熱量分が次の日の初期蓄熱量Ｓ（０）になる。この翌日に消費する熱量分としては、例えば、当日の運転開始時刻ａと同じ時刻までの分を設定するなど、いずれにしても設定値であって予め特定できるものである。
例えば、熱需要分の25％分を設定するとすれば、
【数３７】

となり、予め特定される熱需要と放熱分とによって特定される。
また、当日の運転開始時刻ａと同じ時刻までの分を設定するとすれば、
【数３８】

となり、当日の運転開始時刻ａによって自ずと特定される。
【００４３】
これらにより、前述した（１７）式が次の通りに表される。
【数３９】

ここで、ｔは、翌日に予定した熱量分を消費しきる時刻を当日（所定周期Ｔ）に加えた時刻である。
例えば、午後５時（１７時）から翌日の午前２時まで運転したとして、表−１に基づけば、初期蓄熱量Ｓ（０）が零であったとすれば、当日の午後５時（１７時）から午後１２時（２４時）までに必要な熱量が24,000×(1/860)kWであるのに対して発生する熱量は７× 2,800×(1/860)kW ＝19,600×(1/860)kW であり、余剰電力分Ｅを電気ヒータ８によって熱に変換した変換熱量Ｈを考慮したとしても4,000 ×(1/860)kW 程度が不足する。また、午前中の熱需要分 2,000×(1/860)kW があり、放熱分を見込んだとして 6,500×(1/860)kW 以上が初期蓄熱量Ｓ（０）として必要である。
【００４４】
したがって、翌日分に消費することを前提とする場合に、前述した（１９）式や（２０）式のようにして翌日に消費する分を適宜設定した状態で、１分ごとに運転開始時刻ａを入力して、前述条件式（１）を満たす一次エネルギーの換算値ＰＥ１を求め，先に求めた当日に消費する場合の最小値と比較し、第１および第２の状態を含めた全体で、一次エネルギーの換算値ＰＥ１が最小値となる運転開始時刻ａおよび運転終了時刻ｂとを導出し、熱電併給装置１を定格運転するのである。
【００４５】
以上のようにして、需要変化特定手段２３によって特定される熱需要ｈ（ｔ）、電力需要ｅ（ｔ）に応じ、上記一次エネルギーの換算値ＰＥ１が最小となるように１日間における熱電併給装置１の運転開始時刻ａと運転終了時刻ｂとを導出し、その時刻でもって熱電併給装置１を定格運転することにより、熱電併給装置１からの熱を捨てずに、省エネルギー性を向上する最適な状態でコージェネレーションシステムを運転できる。
【００４６】
次に、第２実施例について説明する
この第２実施例では、電力需要ｅ（ｔ）が定格発電量１ｋｗよりも小さいところでは、電力需要ｅ（ｔ）に合わせて発電し、定格発電量１ｋｗよりも大きいところでは、定格発電量１ｋｗで発電するように熱電併給装置１を運転する。
【００４７】
この第２実施例では、前述第１実施例のような電気ヒータを用いないものであり、構成的には、図１および図２の電気ヒータ８およびスイッチ回路２０を無くした構成となる。そして、運転開始時刻ａと運転終了時刻ｂとを想定すれば、図９の（ａ）および（ｂ）の熱需要と電力需要の経時的変化のグラフに示すように、熱電併給装置１の運転によって得られる熱量Ｄ’が総熱量となり、下記式（２１）で表される。
【数４０】

ここで、ｅ（ｔ）＜１であれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧１であれば、Ｅ（ｔ）＝１
である。また、Ｂ［Ｅ（ｔ）］は、電力量Ｅ（ｔ）における熱電併給装置１の発生熱量であり、Ｂ［１］＝3.25である。
【００４８】
熱需要を主体として常に満たすためには、熱電併給装置１の運転に伴って得られる総熱量（＝熱量Ｄ’）が、熱需要ｈ（ｔ）の総量Ａ’相当分（斜線部分Ａ’で示す）と放熱量Ｂ’相当分（斜線部分Ａ’の上部分Ｂ’で示す）とを加算したもの以上になる必要があり、前述第１実施例［（１５）式］と同様な下記（２２）式が成立する。図面上では、Ｄ’＝Ａ’＋Ｂ’として示している。
【数４１】

【００４９】
また、第１実施例と同様に、蓄熱タンク２内に蓄えられている蓄熱量Ｓ（ｔ）は、次のように示すことができ、また、コージェネレーションシステムにおいて、熱需要を賄うために、蓄熱量Ｓ（ｔ）が不足しないことが条件になる。
【００５０】
更に、当日の熱需要分に相当する量の熱の大半を熱電併給装置１により当日に発生させて消費する第１の状態に加えて、負荷電力の多い時間帯で運転して余剰となった熱を翌日に消費する第２の状態を考察する場合、第１実施例と同様にして、前述した（１９）式や（２０）式など、翌日に消費する設定熱量分を予め特定される熱需要と熱電併給装置１によって発生する熱量とによって、初期蓄熱量Ｓ（０）が特定される。
【００５１】
以上のことから、下記条件式（７）が成立する。
【数４２】

ここで、ｅ（ｔ）＜１であれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧１であれば、Ｅ（ｔ）＝１
である。また、Ｂ［Ｅ（ｔ）］は、電力量Ｅ（ｔ）における熱電併給装置１の発生熱量であり、この第２実施例においても、Ｂ［１］＝3.25である。Ｓ（０）は初期蓄熱量を示している。
また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。
【００５２】
これにより、第１実施例と同様に、翌日分に消費することを前提とする場合に、前述した（１９）式や（２０）式のようにして翌日に消費する分を適宜設定した状態で、１分ごとに運転開始時刻ａを入力して、前述条件式（１）を満たす一次エネルギーの換算値ＰＥ１［（３）式］を求め，先に求めた当日に消費する場合の最小値と比較し、第１および第２の状態を含めた全体で、一次エネルギーの換算値ＰＥ１が最小値となる運転開始時刻ａおよび運転終了時刻ｂとを導出し、熱電併給装置１を電力需要に追従させて運転するのである。
すなわち、
ＰＥ１＝ＧＩ・α＋ＢＥ・β……（３）
ここで、ＧＩは運転開始時刻ａから運転終了時刻ｂまでの熱電併給装置の運転に要する燃料供給量であり、次式（４ａ）で表される。αは燃料の一次エネルギーへの換算値である。
【数４３】

ここで、ＧＩ（ｔ）は、負荷電力が定格発電量よりも少ない運転において使用する熱電併給装置によって特定される燃料供給量である。
【００５３】
この結果、このように電力需要ｅ（ｔ）が定格発電量１ｋｗよりも小さいところで、電力需要ｅ（ｔ）に合わせて発電するように熱電併給装置１を運転する場合であっても、第１実施例と同じように、需要変化特定手段２３によって特定される熱需要ｈ（ｔ）、電力需要ｅ（ｔ）に応じ、一次エネルギーの換算値ＰＥ１［（３）式］が最小となるように１日間における熱電併給装置１の運転開始時刻ａと運転終了時刻ｂとを導出し、その時刻でもって熱電併給装置１を定格運転することにより、熱電併給装置１からの熱を捨てずに、省エネルギー性を向上する最適な状態でコージェネレーションシステムを運転できる。
【００５４】
上記第１実施例および第２実施例では、１日間を１周期Ｔとして繰り返して運転することになるが、例えば、生産ラインなどで、３日間とか１週間を１周期Ｔとして繰り返して運転する場合などにも適用でき、要するに、熱需要および電力需要それぞれの経時的変化を予め特定できる所定時間を１周期Ｔとして設定すれば良く、１日間の不足分の電力の投入量ＢＥの（１７）式を、下記式（５）に置換し、１周期Ｔを任意に設定可能な所定時間とすれば良い。
【数４４】

【００５５】
次に、第３実施例について説明する
この第３実施例では、熱需要ｈ（ｔ）の多少に合わせるように熱電併給装置１を５００ｗと定格発電量１ｋｗとで複数段に設定した発電量で運転するものとする。
【００５６】
この第３実施例において、例えば、午前９時までの午前中のピークに合わせて熱電併給装置１を５００ｗで運転し、午前９時以降の夕方のピークに合わせて熱電併給装置１を定格発電量１ｋｗで運転するとして、５００ｗ運転の運転開始時刻ａ₁ と、定格発電量１ｋｗ運転への切り換え、すなわち、定格発電量１ｋｗ運転の運転開始時刻ａ₂ と、その運転終了時刻ａ₃ を想定すれば、図１０のグラフに示すように、熱電併給装置１の運転によって得られる熱量Ｄ１とＤ２と余剰電力分Ｅを電気ヒータ８によって熱に変換した変換熱量Ｈとの和が総熱量Ｄとなり、下記式（２３）で表される。
【数４５】

ここで、ｅ（ｔ）＜１であれば、Ｅ（ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧１であれば、Ｅ（ｔ）＝１
である。また、Ｔ₁ は、５００ｗ運転の運転開始時刻ａ₁ から時刻ａ₂ までの運転時間であり、Ｔ₂ は１ｋｗ運転の運転開始時刻ａ₂ から運転終了時刻ａ₃ までの運転時間である。ｋ₁ は５００ｗ運転時の熱電比を示し、ｋ₂ は１ｋｗ運転時の熱電比を示している。
【００５７】
熱需要を主体として常に満たすためには、熱電併給装置１の運転に伴って得られる総熱量（＝熱量Ｄ＝Ｄ１＋Ｄ２＋Ｈ）が、図１０のグラフに示すように、熱需要ｈ（ｔ）の総量Ａ相当分（斜線部分Ａ１＋Ａ２）と放熱量Ｂ相当分（斜線部分の上部分Ｂ１＋Ｂ２）とを加算したもの以上になる必要があり、前述第１実施例［（１５）式］と同様な下記（２４）式が成立する。
【数４６】

【００５８】
また、第１実施例と同様に、蓄熱タンク２内に蓄えられている蓄熱量Ｓ’（ｔ）は、次のように示すことができ、また、コージェネレーションシステムにおいて、熱需要を賄うために、蓄熱量Ｓ’（ｔ）が不足しないことが条件になる。
【００５９】
更に、当日の熱需要分に相当する量の熱の大半を熱電併給装置１により当日に発生させて消費する第１の状態に加えて、負荷電力の多い時間帯で運転して余剰となった熱を翌日に消費する第２の状態を考察する場合、第１実施例と同様にして、前述した（１９）式や（２０）式など、翌日に消費する設定熱量分を予め特定される熱需要と熱電併給装置１によって発生する熱量とによって、初期蓄熱量Ｓ’（０）が特定される。
【００６０】
以上のことから、下記条件式（２５）が成立する。
【数４７】

ここで、Ｆ₁ 、Ｆ₂ は各設定発電量を、ｋ₁ 、ｋ₂ は各設定発電量の熱電比をそれぞれ示している。Ｈ₂ は余剰電力を電熱変換手段で熱に変換した変換熱量であり、次式で示される。この第３実施例では、Ｆ₁ ＝５００ｗ、Ｆ₂ ＝１ｋｗである。
【数４８】

また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。Ｆ₂ ＝１である。
【００６１】
（２４）式は、前述した第１実施例と同じように特定できるものであり、５００ｗ運転および定格発電量１ｋｗ運転それぞれの運転開始時刻ａ１，ａ２を想定することにより、複数段に設定した発電量での熱電併給装置の運転に要する燃料供給量ＧＩ’を、次式（２６）で求めることができる。
【数４９】

【００６２】
また、１日間の不足分の電力の投入量ＢＥ’は、次式（２７）で求めることができる。
【数５０】

ここで、ＧＰ’は、熱電併給装置の発電量であり、次式（２８）で表される。
【数５１】

５００Ｗ運転状態では電力需要ｅ（ｔ）よりも小さいためにＥ₁ （ｔ）＝Ｆ₁ ＝５００ｗ、１ｋｗ運転状態では電力需要ｅ（ｔ）よりも小さい部分がＥ₂ （ｔ）＝Ｆ₂ ＝１ｋｗであり、電力需要ｅ（ｔ）よりも大きい部分はＥ₂ （ｔ）＝ｅ（ｔ）である。
上記（２７）および（２８）式において、ｅ（ｔ）は、予め特定された電力需要の経時的変化を示す関数である。
【００６３】
これらの燃料供給量ＧＩ’、１日間の不足分の電力の投入量ＢＥ’およびシステムからの放熱量の一次エネルギーの換算値ＰＥ１’を求めれば、
ＰＥ１’＝ＧＩ’・α＋ＢＥ’・β……（９）
となる。ここで、αは燃料の一次エネルギーへの換算値、βは電力の一次エネルギーへの換算値である。
【００６４】
以上のようにして、需要変化特定手段２３によって特定される熱需要ｈ（ｔ）、電力需要ｅ（ｔ）に応じ、上記一次エネルギーの換算値ＰＥ１’が最小となるように、１日間における５００ｗ運転および定格発電量１ｋｗ運転それぞれの運転開始時刻ａ₁ ，ａ₂ 、ならびに、運転終了時刻ａ₂ ，ａ₃ を導出し、それらの時刻でもって熱電併給装置１を運転することにより、熱電併給装置１からの熱を捨てずに、省エネルギー性を向上する最適な状態でコージェネレーションシステムを運転できる。
【００６５】
上記第３実施例では、１日間を１周期として繰り返して運転することになるが、例えば、１週間を１周期として繰り返して運転する場合などにも適用でき、要するに、熱需要および電力需要それぞれの経時的変化を予め特定できる所定時間を１周期として設定すれば良く、１日間の不足分の電力の投入量ＢＥ’の（２７）式を、下記式（１１）に置換し、Ｔを任意に設定可能な所定時間とすれば良い。
【数５２】

この第３実施例における複数段の発電量の設定の仕方としては、各設定発電量の中間を電力需要に追随させる状態にする形態、あるいは、発電量が電力需要を越えない状態で電力需要に極力近づける形態のいずれでも良い。前者の場合、余剰電力分を電気ヒータで熱に変換すれば良い。
【００６６】
また、上記第３実施例では、５００ｗ運転および定格発電量１ｋｗ運転の２種類のステップ運転を行うようにしているが、本発明としては、例えば、７００ｗ運転および定格発電量１ｋｗ運転の２段に設定した発電量の運転を行うとか、５００ｗ運転、７００ｗ運転および定格発電量１ｋｗ運転などの３段以上に設定した発電量の運転を行うようにしても良く、その場合、複数の発電量が変わる時期ａ₁ ，…，ａ_n-1 に基づき、前述条件式（２５）式を下記式（８）に置換するとともに、（２６）式を下記式（１０）に、そして、（２８）式を下記式（１２）にそれぞれ置換すれば良い。ｎは正の整数である。
【数５３】

ここで、Ｓ’（０）は初期蓄熱量を示し、Ｆ₁ 、…、Ｆ_n は各設定発電量を、ｋ₁ 、…、ｋ_n は各設定発電量の熱電比をそれぞれ示している。Ｈ₁ 、Ｈ₂ 、…、Ｈ_n-1 は余剰電力を電熱変換手段で熱に変換した変換熱量であり、次式で示される。
【数５４】

但し、ｅ（ｔ）＜Ｆ_k であれば、Ｅ_k （ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆ_k であれば、Ｅ_k （ｔ）＝Ｆ_k
ｋは１からｎ−１までの整数である。
Ｅ_k （ｔ）は、負荷電力が定格電力を越える場合は定格電力量となり、負荷電力が定格電力より小さい場合はその負荷電力量となる電力量である。また、ｈ（ｔ）は、予め特定された熱需要の経時的変化を示す関数であり、ｅｘ（ｔ）はシステムからの放熱量である。
ＰＥ１’＝ＧＩ’・α＋ＢＥ’・β……（９）
【数５５】

【数５６】

但し、ｅ（ｔ）＜Ｆ_k であれば、Ｅ_k （ｔ）＝ｅ（ｔ）
ｅ（ｔ）≧Ｆ_k であれば、Ｅ_k （ｔ）＝Ｆ_k
【００６７】
次に、上記第３実施例のシュミレーションテストの一例について説明する。
１日の電気需要を１５ｋｗ、１日の熱需要を３２．５ｋｗとし、５００ｗ運転の時間を１時間、２時間、３時間、４時間、５時間と変化させるとともに、放熱率を０％、１％、３％、５％、１０％に想定して、熱需要＝排熱となるように定格発電量１ｋｗの運転と組み合わせた。
その結果、図１１のデータシートに示す計算結果が得られた。
【００６８】
今、１周期Ｔ内での熱需要分に相当する量の熱を前記熱電併給装置１により前記１周期Ｔ内で発生させて消費する第１の状態として、放熱率が３％で５００ｗ運転の時間を５時間にした場合（Ｍで示す）と、１周期Ｔ内の負荷電力の多い時間帯で熱電併給装置１を運転して余剰となった熱を次の周期で消費する第２の状態として、放熱率が１０％で５００ｗ運転の時間を３時間にした場合（Ｌで示す）とで比較すれば、後者の場合の方が、放熱率が高いにもかかわらず、一次エネルギーとしては小さくできている。
【００６９】
このように、運転時刻の設定と、熱電併給装置１を運転すべき発電量の設定とを変えることによって、放熱率が高くても一次エネルギーを小さくできる場合が多々あり、上述のように運転時刻を求めることで省エネルギーを図ることができるものであり、本発明が極めて有用であることが明らかである。
【００７０】
本発明は、家庭用や製造工場や商用ビルなどの各種の用途のコージェネレーションシステムに適用できる。
【００７１】
【発明の効果】
以上の説明から明らかなように、請求項１および請求項２に係る発明のコージェネレーションシステムの運転方法によれば、電力需要が定格発電量よりも小さいときの電力需要を越える余剰の電力を電熱変換手段によって熱に変換し、熱電併給装置を定格発電量で運転して発電するから、定格発電量よりも小さい発電量で運転する場合に比べて見掛け上の発電効率を高くできる。
しかも、例えば、１日などの１周期内にとどまらず、翌日の午前分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転するから、放熱ロスのより少ない状態を選択して熱電併給装置を運転でき、省エネルギー性を向上できる。
【００７２】
また、請求項３および請求項４に係る発明のコージェネレーションシステムの運転方法によれば、電力需要が定格発電量を越えるときは熱電併給装置を定格発電量で運転して発電するから発電効率を高くでき、また、電力需要が定格発電量よりも小さいときは熱電併給装置を電力需要に追従して運転して発電し、余剰電力を発生させないようにするから、常時定格運転するよりも効率を向上できるとともに熱に変換するための構成を不用にできる。
しかも、例えば、１日などの１周期内にとどまらず、翌日の午前分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転するから、発電効率を極力高くできるとともに放熱ロスを極力少なくできる状態を選択して熱電併給装置を運転でき、省エネルギー性を向上できる。
【００７３】
また、請求項５および請求項６に係る発明のコージェネレーションシステムの運転方法によれば、熱電併給装置を複数段に設定した発電量で運転するから、常時一定出力よりも余剰電力が少なく効率良い運転ができる。
しかも、例えば、１日などの１周期内にとどまらず、翌日の午前分の熱需要など次の１周期内の熱需要の一部を賄う場合まで想定し、蓄熱タンクに貯めた熱が消費までの間に放熱する分と、不足分の電力を買電手段で賄うことをも考慮して、全体の一次エネルギーへの変換値が最小となるように運転するから、発電効率を極力高くできるとともに放熱ロスを極力少なくできる状態を選択して熱電併給装置を運転でき、省エネルギー性を向上できる。
【図面の簡単な説明】
【図１】本発明に係るコージェネレーションシステムを示すシステム構成図である。
【図２】ブロック図である。
【図３】第１実施例の説明に供する電力需要の経時的変化を示すグラフである。
【図４】第１実施例の説明に供する熱需要の経時的変化を示すグラフである。
【図５】第１実施例の説明に供する電力需要と熱需要と発生熱量との相関を示すグラフである。
【図６】第１実施例の説明に供する熱需要と発生熱量との相関を示すグラフである。
【図７】第１実施例の説明に供する熱需要と発生熱量との相関を示すグラフである。
【図８】第１実施例の説明に供する電力需要と熱需要と発生熱量との相関を示すグラフである。
【図９】第２実施例の説明に供する電力需要と熱需要と発生熱量との相関を示すグラフである。
【図１０】第３実施例の説明に供する電力需要と熱需要と発生熱量との相関を示すグラフである。
【図１１】第３実施例のシュミレーションの実験結果を示すデータシートである。
【符号の説明】
１…熱電併給装置
２…蓄熱タンク
８…電熱変換手段としての電気ヒータ
１９…買電手段
２３…需要変化特定手段[0001]
BACKGROUND OF THE INVENTION
The present invention provides an operation of a cogeneration system configured to provide both electric power and heat by providing a cogeneration device that generates electric power and heat, such as an integrated engine and generator or a fuel cell. Regarding the method.
[0002]
[Prior art]
As this kind, there was one that was configured to follow the power demand, but if the total amount of heat generated by the combined heat and power unit is more than necessary, the excess heat is discarded It is useless.
[0003]
Therefore, a heat storage tank for storing the heat generated by the combined heat and power supply device is provided, temperature sensors are provided at predetermined locations above and below the heat storage tank, and the heat storage tank is full or almost empty based on the temperature change. The operation of the combined heat and power supply device is controlled to meet the heat demand.
[0004]
[Problems to be solved by the invention]
However, even when heat is not actually needed, heat is stored in the heat storage tank, and if the time until the stored heat is consumed is long, the amount of heat released from the heat storage tank increases, and this heat loss is reduced. For this reason, there is a drawback that the energy saving performance is lowered.
[0005]
As operation modes, there are rated operation, operation that follows the power demand in the portion below the rating, and operation with multiple stages of power consumption, but in either case, heat is consumed to reduce heat dissipation loss If you try to operate the combined heat and power supply so that the time until the time is short, it will be operated when the power demand is low, the apparent power generation efficiency or power generation efficiency will decrease, and the energy saving performance will decrease There's a problem.
[0006]
On the contrary, if the power generation efficiency is emphasized and the cogeneration apparatus is operated in a state where the power generation efficiency is high, there is a problem that the energy saving performance is reduced due to the heat radiation loss as described above.
[0007]
  The present invention has been made in view of such circumstances, and claims 1And claim 2An object of the present invention is to operate the combined heat and power supply device in a state where the apparent power generation efficiency is increased as much as possible and the heat dissipation loss is reduced as much as possible, so that energy saving can be improved.3, claim 4, claim 5 and claim 6An object of the present invention is to operate a combined heat and power supply device in a state where power generation efficiency is increased as much as possible and heat dissipation loss is reduced as much as possible, and energy saving can be improved.
[0008]
[Means for Solving the Problems]
  In order to achieve the above-described object, the operation method of the cogeneration system of the invention according to claim 1
  A combined heat and power generation device that generates the rated amount of power and heat;
  A heat storage tank for storing heat generated by the cogeneration device;
  Electrothermal conversion means for converting the electric power generated in the cogeneration device into heat;
  Demand change specifying means for predetermining temporal changes in heat demand and power demand in each of the one period and the next one period, with a predetermined time as one period,
  Power purchase means capable of supplying insufficient power,
  Operation in the first state in which the heat demand in the one cycle or the amount corresponding to the majority of the heat demand is generated and consumed in the one cycle by the combined heat and power device and in a time zone with a high load power Assuming each of the second states in which the excess heat is consumed in the next cycle, the operation start times obtained by dividing the one cycle by the set time interval are sequentially input, and the heat storage amount in the heat storage tank is 0. As described above, the optimum operation state in which the converted value of the primary energy is minimized is obtained from the whole of the first and second states, and the obtained operation start time and the operation start time in the optimum operation state are obtained. According to the operation end time derived from the above, the combined heat and power device is operated at a rated power generation amount, and surplus power when the power demand is smaller than the rated power generation amount is converted into heat by the electrothermal conversion means.
  Moreover, in order to achieve the above object, the operation method of the cogeneration system of the invention according to claim 2
  In the operation method of the cogeneration system according to claim 1,
  A predetermined period of time is defined as one period T, and a demand change specifying method for specifying in advance a temporal change in each of the heat demand and power demand in each of the one period T and the next one period T.StepPrepared,
  In the first state in which heat corresponding to the heat demand in the period T or most of the heat demand is generated and consumed in the period T by the combined heat and power supply device, and in a time zone with a large load power Assuming each of the second states in which excess heat is consumed in the next cycle, the operation start time a obtained by dividing the one cycle T at every set time interval is sequentially input, and the heat storage tank The first and second states are the optimum operating states in which the fluctuation value S (t) of the heat storage amount always satisfies the following conditional expression (1) and the converted value PE1 [Expression (3)] of the following primary energy is minimized. The operation of the combined heat and power unit with the rated power generation amount and the power demand is determined according to the operation start time a in the optimum operation state obtained and the operation end time b derived from the operation start time a. Less than when It is characterized by converting into heat by the electrothermal converting means power.
[Expression 15]

  Here, S (0) indicates the initial heat storage amount. F indicates the rated power generation amount, and k indicates the thermoelectric ratio.
  Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system. And H is the conversion calorie | heat amount which converted surplus electric power into heat with the electrothermal conversion means, and integrates the part of F> e (t), and is represented by following (2) Formula.
[Expression 16]

  However, if e (t) <F, E (t) = e (t)
        If e (t) ≧ F, E (t) = F
  Here, E (t) is the rated power amount when the load power exceeds the rated power, and is the power amount that becomes the load power amount when the load power is smaller than the rated power. It is a function which shows the time-dependent change of the specified electric power demand.
  PE1 = GI · α + BE · β (3)
  Here, GI is the fuel supply amount required for the operation of the combined heat and power supply device from the operation start time a to the operation end time b, and is represented by the following equation (4). α is a value converted into the primary energy of the fuel.
[Expression 17]

  Here, GI (t) is a fuel supply amount specified by the combined heat and power device to be used.
  BE is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (5). β is a value converted into primary energy of electric power.
[Expression 18]

  Here, GP is a power generation amount of the combined heat and power supply device, and is expressed by the following equation (6).
[Equation 19]

  However, if e (t) <F, E (t) = e (t)
        If e (t) ≧ F, E (t) = F
[0009]
  Claims3In order to achieve the above-described object, the operation method of the cogeneration system of the invention according to
  A cogeneration device that generates power and heat that can be operated according to the load when the load power is less than the rated power generation amount; and
  A heat storage tank for storing heat generated by the cogeneration device;
  Demand change specifying means for predetermining temporal changes in heat demand and power demand in each of the one period and the next one period, with a predetermined time as one period,
  Power purchase means capable of supplying insufficient power,
  The first state in which the heat corresponding to the heat demand within the one cycle is generated and consumed within the one cycle by the combined heat and power supply device, and the surplus by operating in a time zone with a large load power Assuming each of the second states in which the consumed heat is consumed in the next cycle, the operation start time obtained by dividing the one cycle by the set time interval is sequentially input, and the heat storage amount in the heat storage tank becomes 0 or more. In this manner, the optimum operating state in which the converted value of primary energy is minimized is obtained from the whole of the first and second states, and is derived from the obtained operation start time and the operation start time in the optimum operation state. According to the operation end time, the cogeneration apparatus is operated with a rated power generation amount, and when the power demand is smaller than the rated power generation amount, the operation is performed following the change in the power demand.
  Further, the operation method of the cogeneration system of the invention according to claim 4 is to achieve the above-described object,
  In the operation method of the cogeneration system according to claim 3,
  A predetermined period of time is defined as one period T, and a demand change specifying method for specifying in advance a temporal change in each of the heat demand and power demand in each of the one period T and the next one period T.StepPrepared,
  A first state in which heat corresponding to the heat demand within the one cycle T is generated and consumed within the one cycle T by the combined heat and power supply device, and is operated in a time zone where the load power is large. Assuming each second state in which the excess heat is consumed in the next cycle, the operation start time a obtained by dividing the one cycle T at every set time interval is sequentially input, and the amount of heat stored in the heat storage tank The optimum operating state in which the fluctuation value S (t) always satisfies the following conditional expression (7) and the converted value PE1 [Expression (3)] of the following primary energy is minimized from the entirety of the first and second states. Based on the obtained operation start time a in the optimum operation state and the operation end time b derived from the operation start time a, the cogeneration device is operated at the rated power generation amount and the power demand is smaller than the rated power generation amount. Sometimes power demand changes It is characterized by operating so as to follow.
[Expression 20]

  Here, S (0) indicates the initial heat storage amount, and E (t) is the rated power amount when the load power exceeds the rated power, and the power that is the load power amount when the load power is smaller than the rated power. Amount. B [E (t)] indicates the amount of heat generated by the combined heat and power device at the amount of power E (t).
  Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
  PE1 = GI · α + BE · β (3)
  Here, GI is the fuel supply amount required for the operation of the combined heat and power device from the operation start time a to the operation end time b, and is represented by the following equation (4a). α is a value converted into the primary energy of the fuel.
[Expression 21]

  Here, GI (t) is the fuel supply amount specified by the combined heat and power supply device used in the operation where the load power is less than the rated power generation amount.
  BE is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (5). β is a value converted into primary energy of electric power.
[Expression 22]

  Here, GP is a power generation amount of the combined heat and power supply device, and is expressed by the following equation (6).
[Expression 23]

  However, if e (t) <F, E (t) = e (t)
        If e (t) ≧ F, E (t) = F
  In the above formulas (5) and (6), e (t) is a function indicating a change in power demand with time specified in advance.
[0010]
  Claims5In order to achieve the above-described object, the operation method of the cogeneration system of the invention according to
  A combined heat and power device that operates with the power generation amount set in multiple stages and generates the power and heat of the set power generation amount,
  A heat storage tank for storing heat generated by the cogeneration device;
  Demand change specifying means for predetermining temporal changes in heat demand and power demand in each of the one period and the next one period, with a predetermined time as one period,
  Power purchase means capable of supplying insufficient power,
  The first state in which the heat corresponding to the heat demand within the one cycle is generated and consumed within the one cycle by the combined heat and power supply device, and the surplus by operating in a time zone with a large load power Assuming each of the second states in which the generated heat is consumed in the next cycle, the cycle is adjusted to the electric load, the operation is performed with the power generation amount set in a plurality of stages, and the time when the power generation amount in the plurality of stages changes The operation states of the set power generation amounts in a plurality of stages are sequentially input so that the heat storage amount in the heat storage tank becomes 0 or more, and the optimum operation state in which the converted value of the total primary energy is minimized is the first and The thermoelectric power supply device is operated with a set power generation amount in a plurality of stages according to the operation start time in the optimum operation state obtained from the entire second state.
  In order to achieve the above-mentioned object, the operation method of the cogeneration system of the invention according to claim 6
  In the operation method of the cogeneration system according to claim 5,
  A first state in which heat corresponding to the heat demand within the one cycle T is generated and consumed within the one cycle T by the combined heat and power supply device, and is operated in a time zone where the load power is large. Assuming each second state in which surplus heat is consumed in the next cycle, the one cycle T is adjusted to the electric load, and is operated with a power generation amount set in a plurality of stages. Change time a₁ , ..., a_n-1(Where n is a positive integer) is sequentially input to each of the operating states of the set power generation amount of a plurality of stages, and the fluctuation value S ′ (t) of the heat storage amount in the heat storage tank always satisfies the following conditional expression (8), The optimum operating state where the following converted primary energy PE1 ′ [Equation (9)] is minimized is obtained from the entire first and second states, and the operation start time a in the obtained optimum operating state is determined.₁ , ..., a_n-1 The heat and power combined device is operated with a set power generation amount in a plurality of stages.
[Expression 24]

  Here, S ′ (0) indicates the initial heat storage amount, and F ′₁ ... F_n Indicates each set power generation amount, k₁ ..., k_n Indicates the thermoelectric ratio of each set power generation amount. H₁ , H₂ ... H_n-1 Is the amount of conversion heat obtained by converting surplus power into heat by the electrothermal conversion means, and is expressed by the following equation.
[Expression 25]

  However, e (t) <F_k If so, E_k (T) = e (t)
        e (t) ≧ F_k If so, E_k (T) = F_k
  k is an integer from 1 to n-1.
  E_k (T) is an amount of electric power that becomes each set electric power generation amount when the load electric power exceeds each set electric power generation amount, and an electric energy that becomes the load electric power amount when the load electric power is smaller than each set electric power generation amount. Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
  PE1 '= GI' · α + BE '· β (9)
  Here, GI 'is the operation start time a of the operation set in each of the plurality of stages.₁ , ..., a_n-1Is the total fuel supply amount required for operation of the combined heat and power device, and is expressed by the following equation (10). n is a positive integer, and GI ′ (t) is a fuel supply amount specified by a combined heat and power device that is operated due to power generation in a plurality of stages. α is a value converted into the primary energy of the fuel.
[Equation 26]

  BE ′ is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (11). β is a value converted into primary energy of electric power.
[Expression 27]

  Here, GP ′ is a power generation amount of the combined heat and power supply device, and is represented by the following equation (12).
[Expression 28]

  However, e (t) <F_k If so, E_k (T) = e (t)
        e (t) ≧ F_k If so, E_k (T) = F_k
  In the above equations (11) and (12), e (t) is a function indicating a change in power demand with time specified in advance.
[0011]
[Action]
  Claim 1And claim 2According to the configuration of the operation method of the cogeneration system according to the invention, the cogeneration system is operated with the rated power generation amount to generate power, and the surplus power exceeding the power demand when the power demand is smaller than the rated power generation amount is Converted into heat by the conversion means, while the shortage of electricity is covered by the power purchase means, the heat demand is met by the converted heat and the heat generated by the combined heat and power supply device, and the heat required later is stored in the heat storage tank. Can meet the heat demand. At this time, for example, not only within one cycle such as one day, but also to cover a part of the heat demand within the next one cycle such as the morning or daytime heat demand of the next day, and stored in the heat storage tank Considering the amount of heat that is dissipated before consumption and the supply of shortage of electricity with the power purchase means, the operation is performed so that the converted value to the primary energy is minimized.
[0012]
  Claims3 and claim 4According to the configuration of the operation method of the cogeneration system according to the invention, when the power demand exceeds the rated power generation amount, the cogeneration system is operated with the rated power generation amount to generate power, and the power demand is smaller than the rated power generation amount. Is operated by following the electricity demand to generate electricity, and the shortage of electricity is covered by the power purchase means and the heat generated by the combined heat and power supply device is used to supply the heat demand and the heat required later. It can be stored in a heat storage tank to meet the heat demand. At this time, for example, not only within one cycle such as one day, but also to cover a part of the heat demand within the next one cycle such as the morning or daytime heat demand of the next day, and stored in the heat storage tank Considering the amount of heat that is dissipated before consumption and the supply of shortage of electricity with the power purchase means, the operation is performed so that the converted value to the primary energy is minimized.
[0013]
  Claims5 and claim 6According to the configuration of the operation method of the cogeneration system according to the invention, for example, within a predetermined period of time such as one day, the cogeneration system is operated with the power generation amount set in a plurality of stages and generates power. To cover the electricity demand with the power purchase means and the heat generated by the combined heat and power supply and the surplus power that exceeds the power demand when the power demand is smaller than the rated power generation amount by the heat converted by the electrothermal conversion means, In addition, the heat required later can be stored in the heat storage tank to meet the heat demand. At this time, for example, not only within one cycle such as one day, but also to cover a part of the heat demand within the next one cycle such as the morning or daytime heat demand of the next day, and stored in the heat storage tank Considering the amount of heat that is dissipated before consumption and the supply of shortage of electricity with the power purchase means, the operation is performed so that the converted value to the primary energy is minimized.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system configuration diagram showing a first embodiment of a cogeneration system, wherein 1 is a combined heat and power supply device, and 2 is a heat storage tank.
[0015]
A circulation pipe 4 having a first pump 3 is connected to the heat storage tank 2 from the bottom side to the top. A heat exchanger 5 is provided in the circulation pipe 4, and a heat recovery circulation pipe 7 including a second pump 6 is connected across the cogeneration apparatus 1 and the heat exchanger 5.
[0016]
With this configuration, the water taken out from the lower part of the heat storage tank 2 is heated by the heat from the combined heat and power supply device 1, and the heated heat storage water is returned to the heat storage tank 2 to store heat.
An electric heater 8 serving as an electrothermal conversion means is provided at a location downstream of the heat exchanger 5 in the circulation pipe 4, and when the electric power generated by the cogeneration apparatus 1 is surplus, the surplus power is converted into heat to store heat. The water taken out from the lower part of the tank 2 is heated, and the heated heat storage water can be stored in the heat storage tank 2. In the figure, reference numeral 9 denotes a hot water supply pipe for hot water supply.
[0017]
An output circulation pipe 10 is connected to the circulation pipe 4 in series with the heat exchanger 5, and a heating heat exchanger 11 is provided in the output circulation pipe 10. In addition, a heating device 14 for central heating, such as an indoor heater, a floor heater, and a bathroom dryer, is connected via a heating circulation pipe 13 provided with a third pump 12.
[0018]
A power line 15 for extracting generated power is connected to the combined heat and power supply apparatus 1, and an electric load 16 such as a lighting device or an electric device is connected to the power line 15. Further, a commercial power line 18 is connected to the power line 15 via a protection device 17 for preventing a reverse power flow, and a power purchase means 19 is configured so that power from the commercial power source can be input when the generated power is insufficient. .
[0019]
In addition, the electric heater 8 is connected to the power line 15 via the switch circuit 20, and the electric heater 8 is energized when surplus power is generated. The electric heater 8 may be provided in the heat recovery circulation pipe 7 as indicated by a two-dot chain line. In the figure, reference numeral 21 denotes a backup gas boiler.
[0020]
A microcomputer 22 is connected to the cogeneration apparatus 1 and the switch circuit 20.
The microcomputer 22 has a learning function. As shown in the block diagram of FIG. 2, the demand change specifying means 23, the operation time input means 24, the calculation means 25, the comparison means 26, and the operation control means 27 are provided. It has been.
[0021]
In the demand change specifying means 23, based on the data stored by the learning function described above, as shown in the graphs of FIG. 3 and FIG. Power demand e (t) and heat change h (t) such as hot water supply or heating over time can be specified in advance. Table 1 shows numerical examples of changes over time of the heat demand h (t) such as the hot water supply and heating. 3 and 4 show an average value of a large number of consumers and show it as a schematic change.
[Table 1]

[0022]
That is, the demand change on the previous day, the demand change on the same day of the week before, and the like are sequentially stored, and based on those demand changes, the heat demand h (t) for the first day of the current day and the first day of the next day, The change with time of (t) can be specified in advance.
[0023]
The operation time input means 24 sequentially inputs operation start times a obtained by dividing one day as one cycle T at set time intervals such as every minute.
[0024]
In the calculation means 25, the operation time is expressed in the conditional expression described later based on the temporal change in the heat demand h (t) and the power demand e (t) for one day on the current day and one day on the next day from the demand change specifying means 23. By inputting an operation start time a and an operation end time b derived therefrom from the input means 24, a converted value of primary energy is calculated.
[0025]
The comparison means 26 stores the converted value of the primary energy input from the calculation means 25, compares the converted value with the next input conversion value, and compares the smaller conversion value with the operation start time a at that time. And the operation end time b is newly stored, and after the input of the operation start time a for one day is completed, the operation start time a and the operation end time b at which the converted value of the primary energy is minimum are output. It is like that.
[0026]
In the operation control means 27, in response to the operation start time a and the operation end time b from the comparison means 26, a drive signal is output to the cogeneration apparatus 1 and the switch circuit 20, and the converted value of primary energy is minimized. The cogeneration system is to be operated.
[0027]
Next, the conditional expression will be described.
In the first embodiment, the combined heat and power unit 1 is operated with the rated power generation amount (100% load) having the highest power generation efficiency, and the electric heater 8 heats the surplus power whose power demand e (t) is smaller than the rated power generation amount. Shall be converted to Here, 1 kW is exemplified as the rated power generation amount. The rated power generation amount is determined by the combined heat and power supply device to be used, for example, 0.8 kW.
[0028]
First, a first state is assumed in which the heat demand in one day as one cycle T or the amount of heat corresponding to most of the heat demand is generated and consumed in one day by the combined heat and power supply device 1. The total amount A of heat demand h (t) required for the entire day is expressed by the following equation (13)
[Expression 29]

Is required. Moreover, as a whole system, there is heat radiation from the housing of the combined heat and power supply device 1, the heat storage tank 2 and the piping, and the heat radiation amount B can be expressed by the following equation (14) as a function of time.
[30]

It becomes.
[0029]
From these facts, when the operation start time of the combined heat and power supply apparatus 1 is assumed to be a and the operation end time is assumed to be b, the total amount of heat obtained is converted to the converted heat amount obtained by converting surplus power into heat by the electric heater 8. The total amount of heat from the combined heat and power supply device 1 needs to be equal to the sum of the total amount A of heat demand h (t) and the heat dissipation amount B described above.
[0030]
The surplus power E is the operation time (from a to c) in which the power demand e (t) [kw] is smaller than the rated power generation amount 1 kw, as shown in the graph of the change in power demand with time in FIG. The amount of converted heat H obtained by converting the surplus power E into heat by the electric heater 8 is as shown in the graph of the change in heat demand with time in FIG.
[31]

It becomes.
However, if e (t) <1, E (t) = e (t)
If e (t) ≧ 1, E (t) = 1
Here, E (t) is the rated power amount when the load power exceeds the rated power, and is the power amount that becomes the load power amount when the load power is smaller than the rated power.
[0031]
The amount of heat D from the combined heat and power supply device 1 is as follows.
D = F · K · (ba)
It becomes. If F = 1 and k = 3.25, as shown in the graph of FIG.
D = 3.25 (ba)
It becomes.
[0032]
In order to always satisfy the heat demand as a main component, the total heat amount (= heat amount D + conversion heat amount H) obtained with the operation of the combined heat and power supply apparatus 1 is equal to the heat demand h (t) as shown in the graph of FIG. The total amount A equivalent (indicated by the hatched portion A) and the amount of heat radiation B equivalent (indicated by the upper portion B of the shaded portion A) need to be greater than or equal to the following formula (15).
[Expression 32]

However, if e (t) <1, E (t) = e (t)
If e (t) ≧ 1, E (t) = 1
Here, E (t) is the rated power amount when the load power exceeds the rated power, and is the power amount that becomes the load power amount when the load power is smaller than the rated power.
[0033]
The function ex (t) of the heat release amount B is expressed as the heat release amount ST (t) from the heat storage tank 2, the heat release amount PL (t) from the piping, and the heat release amount GE (t) from the housing of the combined heat and power supply device 1. Total, ie
ex (t) = ST (t) + PL (t) + GE (t) (16)
Can be expressed as
[0034]
Each of the heat dissipation amounts ST (t), PL (t), and GE (t) from the heat storage tank 2, the piping, and the housing of the combined heat and power supply device 1 is determined mainly by the heat capacity proportional to the scale at the time of system construction. For example, if a configuration that covers the casing of the pipe and the cogeneration device 1 and the heat storage tank 2 with a heat insulating material is adopted, the heat radiation amount can be suppressed, but the heat insulating effect of the heat insulating material is also specified in advance when the system is constructed. In any case, the amount of heat released from the piping, the casing of the combined heat and power supply device 1 and the heat storage tank 2 can be specified in advance through experiments, calculations, learning effects, and the like.
[0035]
From the above, the heat storage amount S (t) stored in the heat storage tank 2 can be expressed as follows, and in the cogeneration system, in order to cover the heat demand, the heat storage amount S (t ) Is not a shortage. That is,
[Expression 33]

It is. Here, S (0) indicates the initial heat storage amount. For example, the electric power specified in advance, such as setting a necessary amount by the operation start time a of the day (about 12:00 am in the first embodiment). It is appropriately set based on demand and heat demand, and can be specified in advance. Based on Table-1, the initial heat storage amount is 2,000 [× (1/860) kW].
[0036]
In the above equation (15), the heat demand h (t), the power demand e (t), and the time c at which the power demand e (t) exceeds the rated power generation amount are determined by the demand change specifying means 23 as described above. The operation end time b can be specified based on the operation start time a by setting both sides of the equation (15) to be equal.
[0037]
From these facts, by assuming the operation start time a, the fuel supply amount GI required for the operation of the cogeneration apparatus 1 from the operation start time a to the operation end time b can be obtained by the following equation (4). .
[Expression 34]

[0038]
Also, the amount of power BE input for the shortage for one day can be obtained by the following equation (18).
[Expression 35]

Here, GP is a power generation amount of the combined heat and power supply device, and is expressed by the following equation (6).
[Expression 36]

However, if e (t) <F, E (t) = e (t)
If e (t) ≧ F, E (t) = F
Here, E (t) is the rated power amount when the load power exceeds the rated power, and is the power amount that becomes the load power amount when the load power is smaller than the rated power.
In the above formulas (18) and (6), e (t) is a function indicating a change in power demand with time specified in advance.
[0039]
If the fuel supply amount GI, the input amount BE of the shortage of power for one day BE, and the converted value PE1 of the primary energy released from the system are obtained,
PE1 = GI · α + BE · β (3)
It becomes. Here, α is a conversion value of fuel to primary energy, and β is a conversion value of electric power to primary energy. As described above, ex (t) is the amount of heat released from the system.
[0040]
Furthermore, for example, when there is a large amount of power demand in the evening, the power generation efficiency is high, the operation time zone of the combined heat and power supply device 1 is shifted to the evening side, and the energy consumed can be improved by consuming the stored heat the next day Focusing on the fact, there is assumed a second state in which the combined heat and power supply device 1 is operated in a time zone where the load power is large and excess heat is consumed on the next day as the next cycle.
[0041]
When it is assumed that the next day will be consumed, as shown in the graph of changes in heat demand and power demand with time in FIGS. The operation start time a and the operation end time b of the combined heat and power supply apparatus 1 are derived in a state in which 25% is set to be consumed on the next day and includes the amount of heat consumed on the next day.
[0042]
The amount of heat consumed on the next day becomes the initial heat storage amount S (0) of the next day. As the amount of heat consumed on the next day, for example, a part up to the same time as the operation start time a of the day is set.
For example, if you set 25% of the heat demand,
[Expression 37]

And is specified by the heat demand and heat radiation specified in advance.
Also, if you set the minutes up to the same time as the operation start time a of the day,
[Formula 38]

Thus, it is naturally identified by the operation start time a on that day.
[0043]
Accordingly, the above-described equation (17) is expressed as follows.
[39]

Here, t is a time obtained by adding to the day (predetermined period T) the time when the amount of heat scheduled for the next day is consumed.
For example, assuming that the engine was operated from 5:00 pm (17:00) to 2:00 am the next day, and based on Table 1, if the initial heat storage amount S (0) was zero, 5:00 pm (17:00 pm on that day) ) To 12:00 pm (24:00), the amount of heat required is 24,000 x (1/860) kW, but the amount of heat generated is 7 x 2,800 x (1/860) kW = 19,600 x (1/860 ) kW, and even if the converted heat amount H obtained by converting the surplus electric power E into heat by the electric heater 8 is taken into consideration, about 4,000 × (1/860) kW is insufficient. In addition, there is a demand for heat in the morning of 2,000 × (1/860) kW, and if the amount of heat release is expected, more than 6,500 × (1/860) kW is required as the initial heat storage amount S (0).
[0044]
Therefore, when it is assumed that the next day will be consumed, the operation start time a is set every minute in a state where the amount to be consumed on the next day is appropriately set as in the above-described equations (19) and (20). To obtain the converted value PE1 of the primary energy satisfying the conditional expression (1), and compare it with the minimum value in the case of consumption on the day of the previous calculation, and the total including the first and second states. The operation start time a and the operation end time b at which the converted primary value PE1 of the primary energy is the minimum value are derived, and the combined heat and power supply apparatus 1 is rated.
[0045]
As described above, the combined heat and power apparatus for one day so that the converted value PE1 of the primary energy is minimized according to the heat demand h (t) and the power demand e (t) specified by the demand change specifying means 23. The operation start time “a” and the operation end time “b” of 1 are derived, and the combined operation of the thermoelectric generator 1 is performed at that time, so that the heat from the combined heat generator 1 is not thrown away, and the optimum energy saving is improved. The cogeneration system can be operated in the state.
[0046]
Next, the second embodiment will be described.
In the second embodiment, when the power demand e (t) is smaller than the rated power generation amount 1 kW, power is generated in accordance with the power demand e (t), and when the power demand e (t) is larger than the rated power generation amount 1 kW, the rated power generation amount 1 kW. The cogeneration apparatus 1 is operated so as to generate electricity.
[0047]
In the second embodiment, the electric heater as in the first embodiment is not used, and the configuration is such that the electric heater 8 and the switch circuit 20 in FIGS. 1 and 2 are eliminated. Assuming the operation start time a and the operation end time b, the operation of the combined heat and power supply apparatus 1 is performed as shown in the graph of changes in heat demand and power demand with time in FIGS. 9A and 9B. The amount of heat D ′ obtained by the above becomes the total amount of heat, and is represented by the following formula (21).
[Formula 40]

Here, if e (t) <1, E (t) = e (t)
If e (t) ≧ 1, E (t) = 1
It is. B [E (t)] is the amount of heat generated by the cogeneration apparatus 1 at the amount of power E (t), and B [1] = 3.25.
[0048]
In order to always satisfy the heat demand as a main component, the total amount of heat (= heat amount D ′) obtained with the operation of the combined heat and power supply device 1 is equivalent to the total amount A ′ of the heat demand h (t) (the hatched portion A ′). And the amount equivalent to the heat radiation amount B ′ (indicated by the upper portion B ′ of the hatched portion A ′) must be greater than or equal to the following (similar to the above-described first embodiment [Expression (15)]) ( 22) Formula is materialized. In the drawing, D ′ = A ′ + B ′.
[Expression 41]

[0049]
Further, similarly to the first embodiment, the heat storage amount S (t) stored in the heat storage tank 2 can be expressed as follows, and in order to cover the heat demand in the cogeneration system, The condition is that the heat storage amount S (t) is not insufficient.
[0050]
Furthermore, in addition to the first state in which most of the amount of heat corresponding to the heat demand for the day is generated and consumed by the combined heat and power supply device 1 on the day, operation is performed in a time zone with a large amount of load power, resulting in surplus. When considering the second state in which heat is consumed on the next day, as in the first embodiment, the heat for which the set heat amount to be consumed on the next day, such as the above-described equations (19) and (20), is specified in advance. The initial heat storage amount S (0) is specified by the demand and the amount of heat generated by the cogeneration apparatus 1.
[0051]
From the above, the following conditional expression (7) is satisfied.
[Expression 42]

Here, if e (t) <1, E (t) = e (t)
If e (t) ≧ 1, E (t) = 1
It is. B [E (t)] is the amount of heat generated by the cogeneration apparatus 1 at the amount of power E (t), and in this second embodiment, B [1] = 3.25. S (0) indicates the initial heat storage amount.
Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
[0052]
Thus, in the same manner as in the first embodiment, when it is assumed that the next day will be consumed, the amount to be consumed on the next day is set appropriately as in the above-described equations (19) and (20). The operation start time a is input every minute, the converted value PE1 [formula (3)] of the primary energy satisfying the conditional expression (1) is obtained, and the minimum value in the case of consumption on the day obtained earlier Comparing and deriving the operation start time a and the operation end time b at which the converted primary value PE1 of the primary energy becomes the minimum value including the first and second states, and the combined heat and power supply apparatus 1 follows the power demand Drive.
That is,
PE1 = GI · α + BE · β (3)
Here, GI is the fuel supply amount required for the operation of the combined heat and power device from the operation start time a to the operation end time b, and is represented by the following equation (4a). α is a value converted into the primary energy of the fuel.
[Expression 43]

Here, GI (t) is the fuel supply amount specified by the combined heat and power supply device used in the operation where the load power is less than the rated power generation amount.
[0053]
As a result, even when the combined heat and power supply apparatus 1 is operated to generate power in accordance with the power demand e (t) where the power demand e (t) is smaller than the rated power generation amount 1 kw, the first As in the embodiment, the primary energy conversion value PE1 [formula (3)] is minimized according to the heat demand h (t) and the power demand e (t) specified by the demand change specifying means 23. By deriving the operation start time a and operation end time b of the combined heat and power unit 1 in one day, and operating the combined heat and power unit 1 at the rated time, energy is saved without throwing away the heat from the combined heat and power unit 1. The cogeneration system can be operated in an optimal state to improve the performance.
[0054]
In the first embodiment and the second embodiment, the operation is repeated with one period as one cycle T. For example, when the operation is repeated with the production line or the like as one cycle T with three days or one week. In short, it is sufficient to set a predetermined time in which a temporal change in each of the heat demand and the power demand can be specified in advance as one period T, and the formula (17) of the shortage of power input BE for one day Is replaced by the following formula (5), and one cycle T may be set to a predetermined time that can be arbitrarily set.
(44)

[0055]
Next, a third embodiment will be described.
In the third embodiment, it is assumed that the cogeneration apparatus 1 is operated with a power generation amount set in a plurality of stages with 500 w and a rated power generation amount 1 kW so as to match the heat demand h (t).
[0056]
In this third embodiment, for example, the combined heat and power supply device 1 is operated at 500 w in accordance with the morning peak until 9:00 am, and the combined heat and power supply device 1 is operated at the rated power generation amount in accordance with the evening peak after 9:00 am. Assuming operation at 1 kw, operation start time a of 500 w operation₁And switching to the rated power generation 1 kW operation, that is, the operation start time a of the rated power generation 1 kW operation₂And the operation end time a_ThreeAs shown in the graph of FIG. 10, the sum of the heat amounts D1 and D2 obtained by the operation of the cogeneration apparatus 1 and the converted heat amount H obtained by converting the surplus power E into heat by the electric heater 8 is the total heat amount. D, which is represented by the following formula (23).
[Equation 45]

Here, if e (t) <1, E (t) = e (t)
If e (t) ≧ 1, E (t) = 1
It is. T₁Is the operation start time a of 500w operation₁To time a₂Driving time until T₂Is the operation start time a of 1 kW operation₂Operation end time a_ThreeIt is the driving time until. k₁Indicates the thermoelectric ratio during 500w operation, k₂Indicates the thermoelectric ratio during 1 kw operation.
[0057]
In order to always satisfy the heat demand as a main component, the total heat amount (= heat amount D = D1 + D2 + H) obtained with the operation of the combined heat and power supply apparatus 1 is the total amount of heat demand h (t) as shown in the graph of FIG. It is necessary to be equal to or greater than the sum of the portion corresponding to A (shaded portion A1 + A2) and the amount of heat radiation B (upper portion B1 + B2 of the shaded portion), which is the same as in the above first embodiment [Equation (15)] ( Equation 24) holds.
[Equation 46]

[0058]
  Moreover, it is stored in the heat storage tank 2 as in the first embodiment.Heat storage amount S ′ (t)Can be shown as follows, and in the cogeneration system, to meet the heat demand,Heat storage amount S ′ (t)The condition is that there is no shortage.
[0059]
Furthermore, in addition to the first state in which most of the amount of heat corresponding to the heat demand for the day is generated and consumed by the combined heat and power supply device 1 on the day, operation is performed in a time zone with a large amount of load power, resulting in surplus. When considering the second state in which heat is consumed on the next day, as in the first embodiment, the heat for which the set heat amount to be consumed on the next day, such as the above-described equations (19) and (20), is specified in advance. The initial heat storage amount S ′ (0) is specified by the demand and the amount of heat generated by the combined heat and power supply device 1.
[0060]
From the above, the following conditional expression (25) is satisfied.
[Equation 47]

Where F₁, F₂Indicates each set power generation amount, k₁, K₂Indicates the thermoelectric ratio of each set power generation amount. H₂Is the amount of conversion heat obtained by converting surplus power into heat by the electrothermal conversion means, and is expressed by the following equation. In this third embodiment, F₁= 500w, F₂= 1 kw.
[Formula 48]

Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system. F₂= 1.
[0061]
The equation (24) can be specified in the same manner as in the first embodiment described above, and the power generation set in multiple stages by assuming the operation start times a1 and a2 for the 500 w operation and the rated power generation 1 kw operation, respectively. The fuel supply amount GI ′ required for operation of the combined heat and power supply device can be obtained by the following equation (26).
[Equation 49]

[0062]
Further, the amount of power input BE 'for the shortage for one day can be obtained by the following equation (27).
[Equation 50]

Here, GP ′ is the power generation amount of the combined heat and power supply device, and is represented by the following equation (28).
[Equation 51]

E is smaller than the power demand e (t) in the 500W operation state.₁ (T) = F₁= 500w, 1kw operation state, the part smaller than the power demand e (t) is E₂(T) = F₂= 1 kw, and the part larger than the power demand e (t) is E₂(T) = e (t).
In the above equations (27) and (28), e (t) is a function indicating a change in power demand with time specified in advance.
[0063]
If the fuel supply amount GI ′, the input amount BE ′ of the shortage of power for one day, and the converted primary value PE1 ′ of the primary heat radiation amount are obtained,
PE1 '= GI' · α + BE '· β (9)
It becomes. Here, α is a conversion value of fuel to primary energy, and β is a conversion value of electric power to primary energy.
[0064]
As described above, according to the heat demand h (t) and the power demand e (t) specified by the demand change specifying means 23, 500w in one day so that the converted value PE1 ′ of the primary energy is minimized. Operation start time a for each operation and 1 kW rated power generation₁ , A₂, And operation end time a₂, A_Three The cogeneration system can be operated in an optimum state for improving energy saving without throwing away the heat from the combined heat and power supply device 1 by operating the combined heat and power supply device 1 at those times.
[0065]
In the third embodiment, the operation is repeated with one day as one cycle. However, for example, the present invention can be applied to the operation with one week as one cycle. The predetermined time that can identify the change with time is set as one cycle, and the equation (27) of the shortage of power input BE ′ for one day is replaced with the following equation (11), and T is arbitrarily set The predetermined time can be set.
[Formula 52]

As a method of setting the power generation amount in a plurality of stages in the third embodiment, a mode in which the middle of each set power generation amount follows the power demand, or in a state where the power generation amount does not exceed the power demand, Any form that is as close as possible may be used. In the former case, the surplus power may be converted to heat with an electric heater.
[0066]
Further, in the third embodiment, two types of step operation, 500 w operation and rated power generation 1 kw operation, are performed. In the present invention, for example, two steps of 700 w operation and rated power generation 1 kw operation are performed. Operation with the set power generation amount may be performed, or operation with the power generation amount set in three or more stages such as 500 w operation, 700 w operation, and rated power generation amount 1 kw operation may be performed. In this case, a plurality of power generation amounts change. Time a₁, ..., a_n-1Based on the above, the conditional expression (25) is replaced with the following expression (8), the expression (26) is replaced with the following expression (10), and the expression (28) is replaced with the following expression (12). good. n is a positive integer.
[Equation 53]

Here, S ′ (0) indicates the initial heat storage amount, and F ′₁... F_nIndicates each set power generation amount, k₁..., k_nIndicates the thermoelectric ratio of each set power generation amount. H₁, H₂... H_n-1Is the amount of conversion heat obtained by converting surplus power into heat by the electrothermal conversion means, and is expressed by the following equation.
[Formula 54]

However, e (t) <F_kIf so, E_k(T) = e (t)
e (t) ≧ F_kIf so, E_k(T) = F_k
k is an integer from 1 to n-1.
E_k(T) is the amount of rated power when the load power exceeds the rated power, and the amount of power that becomes the load power when the load power is smaller than the rated power. Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
PE1 '= GI' · α + BE '· β (9)
[Expression 55]

[56]

However, e (t) <F_kIf so, E_k(T) = e (t)
e (t) ≧ F_kIf so, E_k(T) = F_k
[0067]
Next, an example of the simulation test of the third embodiment will be described.
The daily electricity demand is 15kw, the daily heat demand is 32.5kw, the 500w operation time is changed to 1 hour, 2 hours, 3 hours, 4 hours and 5 hours, and the heat dissipation rate is 0%, 1 %, 3%, 5%, and 10%, combined with operation with a rated power generation of 1 kW so that heat demand = exhaust heat.
As a result, the calculation result shown in the data sheet of FIG. 11 was obtained.
[0068]
Now, as a first state in which heat corresponding to the heat demand within one cycle T is generated and consumed within the one cycle T by the combined heat and power supply device 1, the heat radiation rate is 3% and the 500w operation is performed. When the time is set to 5 hours (indicated by M), the second state in which surplus heat is consumed in the next cycle by operating the combined heat and power supply device 1 in a time zone with a large load power within one cycle T As compared with the case where the heat dissipation rate is 10% and the 500w operation time is 3 hours (indicated by L), the latter case is smaller in primary energy despite the higher heat dissipation rate. is made of.
[0069]
Thus, by changing the setting of the operation time and the setting of the power generation amount at which the cogeneration apparatus 1 should be operated, there are many cases where the primary energy can be reduced even if the heat dissipation rate is high. It is obvious that the present invention is extremely useful because it is possible to save energy.
[0070]
The present invention can be applied to cogeneration systems for various uses such as home use, manufacturing factories, and commercial buildings.
[0071]
【The invention's effect】
  As is clear from the above description, the claim 1And claim 2According to the operation method of the cogeneration system according to the invention, surplus power exceeding the power demand when the power demand is smaller than the rated power generation amount is converted into heat by the electrothermal conversion means, and the combined heat and power supply device is converted into the rated power generation amount. Since power is generated by operation, the apparent power generation efficiency can be increased as compared with the case of operation with a power generation amount smaller than the rated power generation amount.
  Moreover, for example, it is assumed that the heat stored in the heat storage tank will not be consumed within one cycle such as one day, but will cover a part of the heat demand within the next one cycle such as the heat demand for the next morning. Considering that the amount of heat dissipated during this period and that the shortage of electricity is covered by power purchase means, the system is operated so that the conversion value to the total primary energy is minimized. It is possible to select and operate the combined heat and power supply device, and to improve energy saving.
[0072]
  Claims3 and claim 4According to the operation method of the cogeneration system according to the invention, when the power demand exceeds the rated power generation amount, the combined heat and power generation device is operated with the rated power generation amount to generate power, so that the power generation efficiency can be increased, and the power demand is rated. When it is smaller than the amount of power generation, the combined heat and power unit is operated to generate power by following the power demand, so that excess power is not generated. The configuration can be made unnecessary.
  Moreover, for example, it is assumed that the heat stored in the heat storage tank will not be consumed within one cycle such as one day, but will cover a part of the heat demand within the next one cycle such as the heat demand for the next morning. Considering that the amount of heat dissipated during this period and that the shortage of electricity is covered by power purchase means, the operation is performed so that the total conversion value to primary energy is minimized, so that the power generation efficiency can be made as high as possible. It is possible to operate the combined heat and power supply by selecting a state where heat loss can be reduced as much as possible, and to improve energy saving.
[0073]
  Claims5 and claim 6According to the operation method of the cogeneration system according to the invention, since the combined heat and power supply device is operated with the power generation amount set in a plurality of stages, it is possible to efficiently operate with less surplus power than the constant output at all times.
  Moreover, for example, it is assumed that the heat stored in the heat storage tank will not be consumed within one cycle such as one day, but will cover a part of the heat demand within the next one cycle such as the heat demand for the next morning. Considering that the amount of heat dissipated during this period and that the shortage of electricity is covered by power purchase means, the operation is performed so that the total conversion value to primary energy is minimized, so that the power generation efficiency can be made as high as possible. It is possible to operate the combined heat and power supply by selecting a state where heat loss can be reduced as much as possible, and to improve energy saving.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing a cogeneration system according to the present invention.
FIG. 2 is a block diagram.
FIG. 3 is a graph showing a change in power demand with time for explaining the first embodiment.
FIG. 4 is a graph showing the change over time in heat demand for explaining the first embodiment.
FIG. 5 is a graph showing a correlation among electric power demand, heat demand, and generated heat amount for explaining the first embodiment.
FIG. 6 is a graph showing the correlation between the heat demand and the amount of generated heat for explaining the first embodiment.
FIG. 7 is a graph showing the correlation between the heat demand and the amount of generated heat for explaining the first embodiment.
FIG. 8 is a graph showing a correlation among electric power demand, heat demand, and generated heat amount for explaining the first embodiment.
FIG. 9 is a graph showing a correlation among electric power demand, heat demand, and generated heat amount for explaining the second embodiment.
FIG. 10 is a graph showing a correlation among electric power demand, heat demand, and generated heat amount for explaining the third embodiment.
FIG. 11 is a data sheet showing a result of a simulation experiment of the third embodiment.
[Explanation of symbols]
1 ... Combined heat and power system
2 ... Thermal storage tank
8 ... Electric heater as electrothermal conversion means
19 ... Power purchase
23 ... Demand change identification means

Claims (6)

A combined heat and power generation device that generates the rated amount of power and heat;
A heat storage tank for storing heat generated by the cogeneration device;
Electrothermal conversion means for converting the electric power generated in the cogeneration device into heat;
As a one round-life for a predetermined time, and demand change specifying means for pre-specifying the change over time in the respective heat demand and power demand of one round-life Contact and following one round Kiso been within which each,
Power purchase means capable of supplying insufficient power,
First state to consume is generated in said one rotation period by the cogeneration system the amount of heat corresponding to the heat demand content or the majority within said one rotation period, and, in the load much power time zone was a surplus driving heat assuming respective second state to be consumed by the next cycle, the sequentially inputs the divided operation start time of the one rotation period every time setting interval, in the heat storage tank as the heat storage amount is 0 or more, the optimum operating conditions corresponding value of total primary energy is minimized determined from the whole of the first and second states, the operation start time of the optimum operating conditions determined and by the operation end time which the guided operation start time or al, the heat surplus power when the power demand less than the rated power generation amount by the electrothermal converting means as well as operating the cogeneration device by the rated power generation amount Koji characterized by conversion Method of operating ne configuration system. In the operation method of the cogeneration system according to claim 1,
The predetermined time as one cycle T, with its one period T and the next one period T heat demand and power demand respectively demand changes specific means to pre-specified temporal changes in the respective
In the first state in which heat corresponding to the heat demand in the period T or most of the heat demand is generated and consumed in the period T by the combined heat and power supply device, and in a time zone with a large load power Assuming each of the second states in which excess heat is consumed in the next cycle, the operation start time a obtained by dividing the one cycle T at every set time interval is sequentially input, and the heat storage tank The first and second states are the optimum operating states in which the fluctuation value S (t) of the heat storage amount always satisfies the following conditional expression (1) and the converted value PE1 [Expression (3)] of the following primary energy is minimized. The operation of the combined heat and power unit with the rated power generation amount and the power demand is determined according to the operation start time a in the optimum operation state obtained and the operation end time b derived from the operation start time a. Less than when The method of operating a cogeneration system and converting the power into heat at the electrothermal converting means.

Here, S (0) represents the initial heat storage amount, F represents the rated power generation amount, and k represents the thermoelectric ratio.
Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system. And H is the conversion calorie | heat amount which converted surplus electric power into heat with the electrothermal conversion means, and integrates the part of F> e (t), and is represented by following (2) Formula.

However, if e (t) <F, E (t) = e (t)
If e (t) ≧ F, E (t) = F
Here, E (t) is the rated power amount when the load power exceeds the rated power, and is the power amount that becomes the load power amount when the load power is smaller than the rated power. It is a function which shows the time-dependent change of the specified electric power demand.
PE1 = GI · α + BE · β (3)
Here, GI is the fuel supply amount required for the operation of the combined heat and power supply device from the operation start time a to the operation end time b, and is represented by the following equation (4). α is a value converted into the primary energy of the fuel.

Here, GI (t) is a fuel supply amount specified by the combined heat and power device to be used.
BE is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (5). β is a value converted into primary energy of electric power.

Here, GP is a power generation amount of the combined heat and power supply device, and is expressed by the following equation (6).

However, if e (t) <F, E (t) = e (t)
If e (t) ≧ F, E (t) = F A cogeneration device that generates power and heat that can be operated according to the load when the load power is less than the rated power generation amount; and
A heat storage tank for storing heat generated by the cogeneration device;
As a one round-life for a predetermined time, and demand change specifying means for pre-specifying the change over time in the respective heat demand and power demand of one round-life Contact and following one round Kiso been within which each,
Power purchase means capable of supplying insufficient power,
First state to consume is generated in said one rotation period by the cogeneration system the amount of heat corresponding to the heat demand content in said one rotation period, and operating at high period during the power the heat becomes excessive assume respective second state to be consumed by the next cycle, the sequentially input the divided operation start time of the one rotation period every time setting interval, the heat storage amount of the heat storage tank is set to be greater than 0, the optimum operating conditions corresponding value of total primary energy is minimized determined from the whole of the first and second states, the operation start time of the optimum operating conditions determined and its operation by the operation completion time derived start time or al, and characterized in that operation by following the change in power demand when the power demand as well as operating at rated power generation amount of the cogeneration device is smaller than the rated power generation amount Cogeneration system Beam method of operation. In the operation method of the cogeneration system according to claim 3,
The predetermined time as one cycle T, with its one period T and the next one period T heat demand and power demand respectively demand changes specific means to pre-specified temporal changes in the respective
A first state in which heat corresponding to the heat demand within the one cycle T is generated and consumed within the one cycle T by the combined heat and power supply device, and is operated in a time zone where the load power is large. Assuming each second state in which the excess heat is consumed in the next cycle, the operation start time a obtained by dividing the one cycle T at every set time interval is sequentially input, and the amount of heat stored in the heat storage tank The optimum operating state in which the fluctuation value S (t) always satisfies the following conditional expression (7) and the converted value PE1 [Expression (3)] of the following primary energy is minimized from the entirety of the first and second states. Based on the obtained operation start time a in the optimum operation state and the operation end time b derived from the operation start time a, the cogeneration device is operated at the rated power generation amount and the power demand is smaller than the rated power generation amount. Sometimes power demand changes The method of operating a cogeneration system characterized by operating by following.

Here, S (0) indicates the initial heat storage amount, and E (t) is the rated power amount when the load power exceeds the rated power, and the power that is the load power amount when the load power is smaller than the rated power. Amount. B [E (t)] indicates the amount of heat generated by the combined heat and power device at the amount of power E (t).
Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
PE1 = GI · α + BE · β (3)
Here, GI is the fuel supply amount required for the operation of the combined heat and power device from the operation start time a to the operation end time b, and is represented by the following equation (4a). α is a value converted into the primary energy of the fuel.

Here, GI (t) is the fuel supply amount specified by the combined heat and power device used in the operation where the load power is equal to or less than the rated power generation amount.
BE is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (5). β is a value converted into primary energy of electric power.

Here, GP is a power generation amount of the combined heat and power supply device, and is expressed by the following equation (6).

However, if e (t) <F, E (t) = e (t)
If e (t) ≧ F, E (t) = F
In the above formulas (5) and (6), e (t) is a function indicating a change in power demand with time specified in advance. A combined heat and power device that operates with the power generation amount set in multiple stages and generates the power and heat of the set power generation amount,
A heat storage tank for storing heat generated by the cogeneration device;
As a one round-life for a predetermined time, and demand change specifying means for pre-specifying the change over time in the respective heat demand and power demand of one round-life Contact and following one round Kiso been within which each,
Power purchase means capable of supplying insufficient power,
First state to consume is generated in said one rotation period by the cogeneration system the amount of heat corresponding to the heat demand content in said one rotation period, and operating at high period during the power the heat becomes excessive assume respective second state to be consumed by the next cycle, combined the one round-life to an electrical load, operating power generation amount set in a plurality of stages, the power generation amount of the plurality of stages the time to change sequentially input to each operating state of the setting power of several stages double, as the heat storage amount of the heat storage tank is greater than 0, the optimum operating conditions corresponding value of total primary energy is minimized determined from the whole of the first and second states, the operation start time of the determined optimum operating conditions Consequently, the cogeneration system, characterized by operating the cogeneration device by setting the power generation amount of a plurality of stages how to drive. In the operation method of the cogeneration system according to claim 5,
The predetermined time as one cycle T, with its one period T and the next one period T heat demand and power demand respectively demand changes specific means to pre-specified temporal changes in the respective
A first state in which heat corresponding to the heat demand within the one cycle T is generated and consumed within the one cycle T by the combined heat and power supply device, and is operated in a time zone where the load power is large. Assuming each second state in which surplus heat is consumed in the next cycle, the one cycle T is adjusted to the electric load, and is operated with a power generation amount set in a plurality of stages. The changing times are sequentially input as a ₁ ,..., A _n-1 (n is a positive integer) to each of the operating states of the set power generation amount in plural stages, and the fluctuation value S ′ (t) of the heat storage amount in the heat storage tank. Always satisfies the following conditional expression (8), and the optimum operating state in which the converted value PE1 ′ [Expression (9)] of the following primary energy is minimized is obtained from the entire first and second states. starting time a ₁ of the best operating conditions, ..., by a _n-1, the cogeneration system The method of operating a cogeneration system, characterized in that the operation at the preset amount of power generated by the plurality of stages.

Here, S '(0) indicates an initial quantity of thermal storage, F _1, ..., F _n is the settings power generation amount, k _1, ..., k _n represents the thermoelectric ratio of each set power amount, respectively. H ₁ , H ₂ ,..., H _n-1 are conversion heat amounts obtained by converting surplus power into heat by the electrothermal conversion means, and are expressed by the following equations.

However, if e (t) <F _k , E _k (t) = e (t)
If e (t) ≧ F _k , E _k (t) = F _k
k is an integer from 1 to n-1.
E _k (t) is an electric power amount that becomes each set electric power generation amount when the load electric power exceeds each set electric power generation amount, and becomes an electric power amount that becomes the load electric power when the load electric power is smaller than each set electric power generation amount. Further, h (t) is a function indicating a temporal change in heat demand specified in advance, and ex (t) is an amount of heat released from the system.
PE1 ′ = GI ′ · α + BE ′ · β (9)
Here, GI ′ is the total fuel supply amount required for the operation of the combined heat and power device from the operation start times a ₁ ,..., An _n−1 of the operation set in each of the plurality of stages, and is expressed by the following equation (10). Is done. n is a positive integer, and GI ′ (t) is a fuel supply amount specified by the combined heat and power unit that is operated due to power generation in a plurality of stages. α is a value converted into the primary energy of the fuel.

BE ′ is an input amount of insufficient power within a predetermined time T that is one cycle T, and is represented by the following equation (11). β is a value converted into primary energy of electric power.

Here, GP ′ is a power generation amount of the combined heat and power supply device, and is represented by the following equation (12).

However, if e (t) <F _k , E _k (t) = e (t)
If e (t) ≧ F _k , E _k (t) = F _k
In the above equations (11) and (12), e (t) is a function indicating a change in power demand with time specified in advance.

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