JP4234414B2 - Control method of utility system - Google Patents

Description

で表される。
【００４３】
このように、最適化の計算においては、各蒸気消費装置ＣＰ１１，ＣＰ１２，ＣＰ１３の消費量に変化がないことを条件とする（ステップＳ１０７）。
また、外部に供給される電力の供給量ＣＰ１４は、プラント内で発電される発電量の総量に買電量を加えたものであるが、電力消費装置ＣＰ１４の電力消費量と等しいものとし。この電力消費量ＣＰ１４に変化がないことを条件とする（ステップＳ１０７）。
【００４４】
次いで、図示しないメモリから、補正値、制約値、評価関数等、最適値の計算に必要な条件を読み出す（ステップＳ１０９，Ｓ１１０，Ｓ１１１）。
制御出力制約計算部７１３は、運転変動を最小に抑え、短時間で最適化の計算が実行できるようにするために、最適化計算の探索範囲を設定する（ステップＳ１１１）。
例えば、制御出力制約計算部７１３は、現在の運転値に対して、運転変数の変更の範囲（探索範囲）を±１０％に設定し、この範囲内で変数の変更を行なって、小さい運転変動で最適化の計算を行うようにする。
【００４５】
この後、最適値計算部７１４が最適値の計算を行う（ステップＳ１１３）。この実施形態では、燃料Ａ〜Ｅや電力会社から買う電力、環境のコストを最小にするように評価関数が設定されているので、最適化が可能な、つまり、運転変数の変更が可能な第一の制御ポイントについて、変数を種々に変更しながら、コストが最小になる最適値を探索する（ステップＳ１１２）。なお、この最適化計算は、市販の最適化ソフトを用いて実行することができる。
【００４６】
最適化の計算終了後は、各制御値を送信する制御ポイントを指定して（ステップ１１３）、その制御ポイントが、予め設定された第一の制御ポイントであるか第二の制御ポイントであるかを判断する（ステップＳ１１４）。
第一の制御ポイントである場合は、最適化計算部７１４による最適化計算で得られた制御値に制限を加えて（ステップＳ１１５）、前記第一の制御ポイントの各々に出力する（ステップＳ１１６）。
第二の制御ポイントへの出力値は、最適化計算によって得られた制御値と、第一の制御ポイントの制御値とから自動的に決定される。また、前記制御ポイントが第二の制御ポイントであると判断された場合には、最適化計算の後にプラントの運転条件に変動があったかどうかを判断して（ステップＳ１１７）、運転条件の変動がなければ、自動的に決定された前記制御値に基づいて、制御指令が出力される（ステップＳ１１９）。
【００４７】
運転条件に変動があったときは、最適化計算で得られた制御値を、前記運転条件の変動に応じて変更し（ステップＳ１１８）、その結果を制御指令として出力する。例えば、高圧蒸気回路１０の蒸気圧が低くなったときは、蒸気圧の低下分に応じて、ボイラＡに供給する燃料Ａの量を増やし、バルブの開量を大きくするように、第二の制御ポイントである制御ポイントＳＰ４３及び制御ポイントＳＰ４１に制御指令を出力する。なお、運転条件の変動の検出と、この変動検出に伴う制御値の変更とは、第一の周期内の一定の周期（第二の周期）、例えば１秒間隔で細かく行うようにするとよい。このようにすることで、用役システムの全体を最適化計算の結果に基づいて制御しつつ、最適化計算後に発生した運転変動を、第二の制御ポイントによって吸収することができる。
【００４８】
また、上記した制御値に加える制限としては、例えば、最適化計算で得られた制御値を１０等分して制御指令を出力することが挙げられる。すなわち、ある制御ポイントに対する最適化の制御値が例えば１０である場合において、前記第一の周期が１０分である場合には、一回当たりの制御量を１とし、かつ、この制御量を一分間隔で前記制御ポイントに出力するようにする。
このように、制御ポイントに出力する制御値に一定の制約を設けているのは、用役システムの運転変動を最小に抑制するためである。
【００４９】
発電量・買電量計算部７２３では、各用役システムから収集された運転データや環境データと、最適化計算部７１４で得られた制御値とに基づいて、必要な発電量及び買電量が計算される。
この際、発電量・買電量計算部７２３は、最適化計算で得られた目標買電量に対する必要な電力量を、計算する。すなわち、発電量・買電量計算部７２３は、前記目標買電量に対する電力の不足分を指し、現在の買電量から前記目標買電量を差し引いて求めることができる。そして、得られた結果を制御値として、第一の制御ポイントである制御ポイントＳＰ７１に制御指令を出力する。この際、前記と同様に制御出力の制限を行い、得られた制御値を例えば１０等分して制御ポイントＳＰ７１に制御指令を出力する。
また、買電制御部７２４は、前記した必要な電力量の計算を行った後に、運転条件の変化にともなって前記電力の必要量が増加したとき、この必要量を求めて、蒸気タービン３２の駆動を制御する第二の制御ポイントＳＰ３１に制御指令を出力する。前記運転条件の変化の検出と必要量の計算とは、例えば１秒おきに行われる。
なお、第一の制御部７１による最適化計算の結果、蒸気の大気放出が必要である場合は、制御ポイントＳＰ３２にバルブを開くように制御指令を出力し、蒸気を大気中に放出する。
【００５０】
上記の実施形態によれば、プラント全体の最適化計算を、モデル式を用いて１０分間隔という短周期で行い、プラントを構成する用役システムの一部（第一の制御ポイント）について最適化計算の結果である制御値を割り付けて制御指令を出力し、他の一部（第二の制御ポイント）については、前記一部の用役システムの運転変数を固定した状態で制御を行うように制御を分散化しているので、前記他の一部で最適化計算の後に生じた運転条件の変動を吸収することができ、プラントの運転条件に応じた最適な制御を、短時間で、かつ、自動的に行うことができる。
【００５１】
［第二の実施形態］
最適化計算で蒸気・電力バランスの変化により、運転条件が大きく変化することがある。この場合、大きく変化した状態で、以後この状態が安定的に維持されれば問題ないが、次の計算時に運転条件が元（一回前）の状態に復元することがある。このような場合に、変化後の計算結果に基づいて運転を行うと、多大なコストの無駄が生じる。
そこで、この実施形態では、偏差チェック処理を行い、プラントに無駄が生じるのを可能な限り防止するようにしている。
【００５２】
図６は、偏差チェックを行わない場合の最適化の出力値（実線）と、偏差チェックを行った場合の最適化の出力値（二点鎖線）とを示すグラフ、図７は、偏差チェックを行う場合の処理の手順を示すフローチャートである。図６のグラフにおいては、縦軸に最適化の計算出力（制御値の出力）をとり、横軸に時間をとっている。また、図７において、図５のフローチャートと同一のステップには同一の符号を付すとともに、ステップＳ１１２より前のステップ及びステップ１１３より後のステップについては、図示を省略してある。
【００５３】
最適値を計算（ステップＳ１１２）した後に、前回（一回前）の計算結果と今回の計算結果との差を求め（ステップＳ１２１）、この差が予め設定された値よりも大きいかどうかを判断する（ステップＳ１２２）。そして、この差が予め設定された値よりも小さいとき、指定された制御ポイント（ステップＳ１１３）に対して、制御指令を出力する。
【００５４】
この差が予め設定された値よりも大きいとき、偏差が大であると判断して、得られた最適値による運転変数の変更は行わない。すなわち、前回の最適値計算で得られた結果に基づく制御内容を維持するわけである。
これを図６のグラフを参照しながら説明すると、符号Ｉ及び符号IIで示す最適値の計算時において、前回の最適値の計算結果と今回の最適値の計算結果との差がＳ１，Ｓ２であり、このＳ１，Ｓ２の値が予め設定された値より大きいときは、前回の運転条件を維持する（維持状態を図６のグラフ中、符号III,IVで示す）。
【００５５】
［第三の実施形態］
この第三の実施形態では、蒸気消費装置に必要な蒸気量を供給しつつ、プラント内の電力発生量を最大にすべく、中圧蒸気を最小化するようにしている。
この第三の実施形態の制御方法を実行する制御システムのブロック図を、図８に示す。
第三の実施形態では、図４に示した第一の制御部７１及び第二の制御部７２に加えて、中圧蒸気圧力の極小化の計算を行う図８に示すような第三の制御部７３を備えている。
【００５６】
第三の制御部７３は、用役システムの運転条件を判断する運転条件判定部７３１と、極小圧力の計算を行う極小圧力計算部７３２と、必要な蒸気量を確保するための蒸気圧力制御部７３３とを有している。
中圧蒸気の極小圧力の計算は、ファジー推論によって行われる。そのステップを、図９のフローチャートに示す。
【００５７】
まず、第一の周期（１０分間隔）のタイムアップとともに（ステップＳ２００）、中圧蒸気消費装置ＣＰ１２の蒸気圧を検出する（ステップＳ２０１）。中圧蒸気消費装置ＣＰ１２が複数台あるときは、各々について蒸気圧を検出する。
次に、予め設定された蒸気圧下限値と、各中圧蒸気消費装置ＣＰ１２の蒸気圧との差ΔＰを求める（ステップＳ２０２）。複数台ある中圧蒸気消費装置ＣＰ１２のうち、最小の値を示した差ΔＰ（特にＰＲと記載する）と、このＰＲを検出した中圧蒸気消費装置ＣＰ１２（以下、当該中圧蒸気消費装置と記載する）とを抽出する（ステップＳ２０３）。
【００５８】
次いで、当該中圧蒸気装置ＣＰ１２の圧力変化（前回検出の蒸気圧と今回検出の蒸気圧力との差）を求め（ステップＳ２０４）、プラント内の制御ポイントＳＰ２１，ＳＰ２２の中から任意の制御ポイント（例えばＳＰ２１）を選択して、この制御ポイントについて圧力変化を求める（ステップＳ２０５）。そして、両者について圧力変化の平均値（ＤＰＲ）を求める（ステップＳ２０６）。
そして、上記したＰＲとＤＰＲとに基づいて、ファジー推論を実行する（ステップＳ２０７）。ファジー制御規則は以下の表のとおりであり、ファジー制御のためのメンバーシップ関数は、図１０に示すとおりである。
【００５９】
なお、予めファジー推論の結果（ＰＰ）に上限値と下限値とを設けておき、推論の結果ＰＰが前記上下の限界値の範囲内であるかどうかを判断する（ステップＳ２０８）。
結果ＰＰが、前記範囲内であるときは、現在の中圧上記の目標値に対してファジー推論値を加算し（ステップＳ２１０）、新たな目標値を設定する（Ｓ２１１）。結果ＰＰが前記範囲外であるときは、現在の中圧上記の目標値に対して上限値又は下限値を加算し（ステップＳ２０９）、新たな目標値を設定する（Ｓ２１１）。
以上で処理を終了する（ステップＳ２１２）。
【００６０】
【表１】

【００６１】
このファジー推論による制御は、圧力復旧方向を優先し、圧力を下げるときはゆっくり下げ、上昇させるときは急激に上昇させるようにしている。
蒸気圧力制御部７３３は、高圧蒸気、中圧蒸気および低圧蒸気の蒸気量を約１秒周期で制御し、蒸気消費装置で必要とする蒸気量を確保する。
なお、高圧蒸気の制御ポイント値は、定圧（１８５０ポンド）に固定し、蒸気発生量はボイラ１１，１２で調整する。高圧蒸気センサーで蒸気圧を検出して、指定圧力になるように、燃料を制御して蒸気を発生させる。この場合の制御ポイントは、ＳＰ４３〜４８であり、使用する燃料は、最適蒸気・電力バランス計算を行う第一の制御部７１（図４参照）が指定する。
【００６２】
中圧蒸気の制御ポイントは、先に求めた蒸気圧（３００ポンド前後）である。
制御ポイントは、図１の制御ポイントＳＰ１１，１２であり、中圧蒸気センサーで蒸気圧力を検出して指定圧力に制御する。
低圧蒸気の制御ポイントは定圧（５０ポンド）に固定してある。制御ポイントは、ＳＰ２１，２２であり、低圧蒸気センサーで蒸気圧力を検出して指定圧力に制御する。
【００６３】
本発明の好適な実施形態について説明してきたが、本発明は上記の実施形態によりなんら限定されるものではなく、本発明の適用範囲内で種々に変更することが可能である。
例えば、本発明が適用されるプラントは上記で説明したものに限定されず、複数の用役システムを有する他のプラントにも適用が可能である。
また、プラントの運転コストに大きな影響を与える用役システムの制御ポイントに限定して、第二の制御ポイントを選択するものとして説明したが、他の条件、例えば、環境に大きな影響を与える用役システムの制御ポイントから第二の制御ポイントを選択するものとしてもよい。
さらに、上記の第三の実施形態では、中圧蒸気を許容範囲内で変更するようにしているが、この許容範囲内での蒸気圧の変更は、高圧蒸気又は低圧蒸気のいずれかであってもよい。
【００６４】
【発明の効果】
このように、本発明によれば、プラント内の制御ポイントを第一の制御ポイントと第二の制御ポイントに区分けし、一方の制御ポイントで最適化計算の結果に基づく制御を行い、他方の制御ポイントで最適化計算の後に生じた運転条件の変化を吸収する制御を行うように役割を分担しているので、運転条件の微妙な変化に対応した最適化制御を短時間で行うことが可能で、かつ、簡単なコンピュータシステムで運転条件の変化に伴って迅速に用役システムの制御を行うことが可能になる。
【図面の簡単な説明】
【図１】本発明の制御方法が適用されるプラントの一例にかかり、その構成を説明するブロック図である。
【図２】蒸気タービンの出力特性を示すグラフである。
【図３】ガスタービン発電機の出力特性を示すグラフである。
【図４】プラントの最適化を行う制御システムの構成を示すブロック図である。
【図５】図４の制御システムによる処理の手順を示すフローチャートである。
【図６】本発明の第二の実施形態にかかり、偏差チェックを行わない場合の最適化の出力値（実線）と、偏差チェックを行った場合の最適化の出力値（二点鎖線）とを示すグラフである。
【図７】偏差チェックを行う場合の処理の手順を示すフローチャートである。
【図８】本発明の第三の実施形態にかかり、この実施形態の制御方法を実行する制御システムのブロック図である。
【図９】本は発明の第三の実施形態にかかり、中圧蒸気の極小圧力を求める手順を示すフローチャートである。
【図１０】ファジー制御のためのメンバーシップ関数を示す図である。
【符号の説明】
１０ 高圧蒸気回路
１１，１２ ボイラ
１３ 圧力計
１４，１６ 高圧蒸気タービン
１５，１７ 発電機
１８ 圧力計
２０ 中圧蒸気回路
２１，２３ 中圧蒸気タービン
２２，２４ 発電機
２５ 圧力計
３０ 低圧蒸気回路
３１ 蒸気放出部
３２ 低圧蒸気タービン
３３ 発電機
４０ 電力供給回路
４１ 電力会社
４２ 電流計
５１ 廃熱回収助燃ボイラ[0001]
BACKGROUND OF THE INVENTION
The present invention is a plant that supplies each energy (utility) such as electricity, steam, and gas to an external facility such as a factory so that the operation of the plant can be operated in an optimum state without waste. The present invention relates to a control method for controlling a utility system.
[0002]
[Prior art]
There is known an optimization control method for efficiently controlling a power plant that supplies energy such as electricity and steam to a factory or the like. In such a control method, conventionally, for the operation of a utility system such as a generator, an optimal load distribution is calculated, for example, approximately every month based on the balance of steam and power supply / supply plans for the next month. There is a problem that the utility and the utility cost are wasted.
Therefore, in order to solve such a problem, for example, in a power plant, a technique for calculating so that the operating conditions of the utility system are optimized in response to changes in demand for steam and electricity that change from moment to moment ( Patent Document 1 and Patent Document 2), and a technique (see Patent Document 3) for calculating an optimum operating condition in real time for the entire plant based on energy balance and energy loss have been proposed.
[0003]
[Patent Document 1]
JP 2000-78749 A (see the description in the detailed description column of the specification)
[Patent Document 2]
Japanese Patent Laid-Open No. 2000-78750 (refer to claims)
[Patent Document 3]
Japanese Patent Laid-Open No. 2000-97001 (refer to the description in the summary section of the invention)
[0004]
The technology described in each of the above patent documents is an effective means for optimizing the load distribution between the parallel service systems when the plant operates the service systems such as boilers and turbines in parallel. .
[0005]
However, even in the technology described in the above-mentioned patent document, it is not possible to cope with a short-term utility balance, for example, a change in steam and power balance, or an unplanned consumption change, and waste is still occurring. is the current situation.
That is, although the technology described in the above-mentioned patent document is suitable for optimization to minimize the cost such as fuel cost, power purchase cost, environmental cost, etc. in the whole plant such as a power plant, the change in weather and electricity consumption, It is not possible to absorb fluctuations in steam consumption, etc., and it is not possible to eliminate the waste of utility or utility costs associated with these changes. In addition, to control the utility system based on the results obtained by the optimization calculation and absorb the fluctuations in various conditions during the control, an advanced and large computer system with a high processing speed is required. There is a problem that the equipment cost of the entire utility system becomes high.
[0006]
[Problems to be solved by the invention]
The present invention has been made in order to solve the above-described problems, and can perform optimization operation control in response to changes in operating conditions in a short time, and the operating conditions can be controlled with a simple computer system. It is an object of the present invention to provide a utility system control method in a plant that can quickly control a utility system in accordance with a change.
[0007]
[Means for Solving the Problems]
  In order to achieve the above object, the invention described in claim 1Including at least a steam generator and a power generatorIn a plant having a plurality of utility systems, a method for controlling the utility system so that the plant can be operated in an optimal state, whereinFormulatedFor each of the utility systems, creating a model, presetting control points to be controlled, collecting operation data from the plant, and based on the collected operation data, In the first cycle, for the utility system, a step of determining whether or not the operating condition can be changed, and for each of the utility system that is determined to be capable of changing the operating condition, a variable in the model is set. A step of performing an optimization calculation for optimal operation of the plant, and selecting a first control point from the control points according to a preset procedure, and the first control point A control point other than the second control point, and the first control point and the second control point And outputting a control command based on the result of the optimization calculation, with respect to the second control point, in a second cycle set by the first period,The plantAnd a step of outputting a control command so as to absorb the change of the operating condition generated inAt least one of the first control point and the second control point, a control value obtained as a result of the optimization calculation is applied a plurality of times within the corresponding first period or second period, respectively. Divide into outputIt is a control method.
[0008]
According to this method, first, optimization calculation for optimal operation of the entire plant is performed in a state where the amount of energy supply such as steam and electric power to the outside is constant. Prior to this, a control point for performing control using the result of the optimization calculation is determined in advance. Next, a first control point and a second control point are selected from the control points. The first control point can be arbitrarily selected according to a predetermined procedure, for example, a control point not performing pressure control, a control point not performing power adjustment as a first control point, It can be selected at every optimization calculation. After the first control point is determined, a control point other than the first control point can be determined as the second control point.
A control command based on the result of the optimization calculation is output to the first control point and the second control point, but changes in various conditions during the control are absorbed by the control of the second control point.
Thus, in the present invention, the control point is divided into the first control point and the second control point, and the control based on the result of the optimization calculation is performed at the first control point. Since variations in conditions are absorbed, processing can be performed quickly with a simple system.
[0009]
  As described in claim 2, the first control point and the second control point are:One utility system is provided with a plurality of control points for supplying fuel, and one control point of the plurality of control points is either the first control point or the second control point, and the other The control point may be selected to be the remaining first control point or the second control point.
  For example, when two types of fuel are supplied to a boiler, if the total amount of fuel supplied to the boiler and the amount of one of the two types of fuel are determined by the optimization calculation, The amount of the other fuel is inevitably determined. Therefore, the control is facilitated by setting the control point for controlling the supply of the one fuel as the first control point and the control point for controlling the supply of the other fuel as the second control point.
[0010]
  Also,Claim 1In at least one of the first control point and the second control point,The control value obtained as a result of the optimization calculation is output in a plurality of times within the corresponding first period or second period.It is preferable to output a command based on the result of the optimization calculation by adding constraints.
  As the above-mentioned constraints,Claim 3As described inThe control values output in a plurality of times are output at equal intervals, and substantially the same control amount is set for each output timing until the control value obtained as a result of the optimization calculation is obtained. Accumulated control value is outputGood. For example, the result obtained by the optimization calculation is sufficiently divided, the first period is also sufficiently divided, and a control command based on the result that is sufficiently divided for each divided period is output. By doing in this way, the driving | running | working fluctuation | variation of a utility system can be suppressed to the minimum.
[0011]
  Claim 4In the invention described in the above, the change of the variable in the model is based on the actual measurement value obtained from the operation data., Having an upper limit and / or a lower limitThis is a control method performed within the range. In this case, it is preferable to determine the variable change range based on the current operation data, and in this way, operation fluctuations of the plant and the utility system can be minimized.
  The optimization calculation is performed by changing various variables in each model. However, as the number of models increases, the number of variables to be changed increases, and much time is spent on the optimization calculation. Therefore, by providing a certain limit to the variable change range, the time required for the optimization calculation can be shortened.
[0012]
  Claim 5The invention described in (1) further includes a step of comparing the calculation result of the current optimum value with the calculation result of the previous optimum value, and when the difference between the two is larger than a preset value, the utility system This is a control method for temporarily suspending the change of the operating condition.
  Due to changes in the balance of steam, power, etc., the calculation result of the optimum value may change greatly between the previous time and this time. If the operating condition is changed in response to such a temporary change in the optimum value, the utility may be wasted.
  Therefore, in the present invention, when the difference between the calculation results of the optimum value between the previous time and the current value is larger than a preset value, the change of the optimum value is temporarily suspended and the operation condition is not changed. .
[0013]
  Claim 6In the invention described in the paragraph, the plant is provided between a plurality of steam supply lines having different steam pressures, the high-pressure side steam supply line, and the low-pressure side steam supply line, and the high-pressure side steam supply line. And a utility system that supplies steam having a reduced pressure to a low-pressure side steam supply line, the steam pressure of at least one of the high-pressure side and the low-pressure side isFluctuations are allowed in the external pressure supplyIt is a control method for performing optimization calculation so that it can be changed within a range.
[0014]
  As a utility system provided between the steam supply line on the high pressure side and the steam supply line on the low pressure side, for example, there is a steam turbine generator. In such a steam turbine generator, the amount of power generation increases as the pressure difference between the steam pressure on the high pressure side and the steam pressure on the low pressure side increases.
  On the other hand, when the steam pressure on the low pressure side is supplied to the outside, the pressure of the steam supplied to the outside is preferably fixed within a certain range.
  Therefore, in order to satisfy both of these conditions, the optimum value may be calculated by changing the steam pressure on the low pressure side within an allowable range of external supply.
  in this case,Claim 7As described in the low pressure sideOr the high-pressure sideAnd the difference between the detected vapor pressure and the lower limit value of the allowable vapor pressure is obtained, and based on this difference, the low pressure side is obtained by fuzzy inference.Or the high-pressure sideIt is advisable to determine the steam pressure.
[0015]
  Claim 8The invention described in 1 is a control method for releasing steam by opening the steam supply line on the low-pressure side to the atmosphere based on the result of the optimization calculation.
  By doing so, the pressure difference between the high pressure side and the low pressure side can be maximized. For example, when the utility system is a steam turbine generator, the maximum power generation amount can be obtained.
[0016]
  Claim 9When the plant has an auxiliary service system, the invention described inFormulatedThis is a control method that creates a model and takes it into account when calculating optimization.
  For example, a plant has a system having auxiliary functions such as a gas turbine that receives power from an external fuel gas to generate power and a waste heat recovery auxiliary combustion boiler, and the power generated by the gas turbine is When supplying steam to the power supply line and steam generated in the waste heat recovery auxiliary combustion boiler to the steam supply line, operation is performed in a more optimal state by considering these auxiliary utility systems in the optimization calculation. be able to.
  In this case, the auxiliary utility system isClaim 10As described above, it may be a gas turbine generator to which steam is supplied as auxiliary power from the plant.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram illustrating the configuration of an example of a plant to which the control method of the present invention is applied.
This plant is for supplying steam and electric power to the high-pressure steam consuming device CP11, the medium-pressure steam consuming device CP12, the low-pressure steam consuming device CP13 and the power consuming device CP14 outside the plant. The boilers 11 and 12 are configured as the mains of utility supply.
[0018]
The steam generated by the boilers 11 and 12 is supplied to the high-pressure steam circuit 10, a part of which is supplied to the high-pressure steam consumption device CP 11, and the other part is connected to the high-pressure steam circuit 10. The high pressure steam turbines 14 and 16 are supplied.
Further, the intermediate pressure steam that has been consumed and reduced in pressure by the two high pressure steam turbines 14 and 16 is supplied to the intermediate pressure steam circuit 20, and a part thereof is supplied to the intermediate pressure steam consumption device CP12. The other part is supplied to the intermediate pressure steam turbines 21 and 23 connected to the intermediate pressure steam circuit 20.
[0019]
Furthermore, the low-pressure steam that has been consumed and reduced in pressure by the two low-pressure steam turbines 21 and 23 is supplied to the low-pressure steam circuit 30, a part of which is supplied to the low-pressure steam consumption device CP 13, and another The unit is supplied to a low pressure steam turbine 32 connected to a low pressure steam circuit 30.
Each steam turbine 14, 16, 21, 23, 31 is provided with a generator 15, 17, 22, 24, 33, and the electric power generated by this generator 15, 17, 22, 24, 33. Is supplied to the power consuming device CP14 via the power supply circuit 40.
[0020]
The power supply circuit 40 is supplied with power from an external power company in order to compensate for the shortage of power supplied from the plant.
Further, this plant has a gas turbine generator 52, which uses the gas supplied from the outside as fuel, generates power using the intermediate pressure steam supplied from the intermediate pressure steam circuit 20 as auxiliary power, and an electric power supply circuit. Power is supplied to 40.
Furthermore, this plant has a waste heat recovery auxiliary combustion boiler 51, which generates high-pressure steam from the waste heat of the gas turbine generator 52 and fuel supplied from the outside and supplies it to the high-pressure steam circuit 10. It is supposed to be.
In the figure, reference numerals 13, 18 and 25 are pressure gauges for measuring the vapor pressure, and reference numeral 42 is an ammeter for measuring the current flowing through the power supply circuit 40. In the optimization control, as a rule, calculation and control of optimum values are performed so that the measured values of these pressure gauges and ammeters do not change.
[0021]
Also, the amount of fuel A, B, C supplied to the boilers 11, 12, the amount of high-pressure steam supplied from the high-pressure steam circuit 10 to the high-pressure steam consumption device, and supplied from the intermediate-pressure steam circuit 20 to the medium-pressure steam consumption device The amount of medium-pressure steam that is supplied, the amount of low-pressure steam that is supplied from the low-pressure steam circuit 10 to the low-pressure steam consumption device, the amount of power that is supplied from the power company (the amount of power purchased), and the power supply circuit 40 The amount of power supplied, the amount of fuel supplied to the gas turbine 52 and the waste heat recovery auxiliary combustion boiler 51, etc. are constantly monitored by a sensor (not shown).
[0022]
In the figure, the symbol SP is a control point controlled by a control command based on the optimum value calculation, and performs valve opening adjustment and the like. For example, the control points SP43 to SP48 control the supply amounts of the fuels A, B, and C supplied to the boilers 11 and 12. The control points SP41 and 42 control the amount of high-pressure steam supplied from the boilers 11 and 12 to the high-pressure steam circuit 10. Furthermore, the control points SP11 and 12 control the supply amount of intermediate pressure steam supplied from the high pressure steam turbines 14 and 16 to the intermediate pressure steam circuit 20, and the control points SP21 and 22 control the intermediate pressure steam turbines 21 and 23. The control point SP31 controls the supply amount of the low-pressure steam supplied from the low-pressure steam circuit 30 to the low-pressure steam turbine 32. Furthermore, a control point SP71 for adjusting the amount of power purchased from the power company 41 is provided in a part of the power supply line from the power company.
[0023]
In the plant of this embodiment, the bypass 19 is provided between the high-pressure steam circuit 10 and the intermediate-pressure steam circuit 20, and the opening / closing control of the bypass 19 is performed by the control point SP61. Further, a bypass 29 is provided between the intermediate pressure steam circuit 20 and the low pressure steam circuit 30, and opening / closing control of the bypass 29 is performed by the control point SP62.
[0024]
A control command according to the result of optimization calculation (hereinafter referred to as a control value) is output to each control point described above. In the present invention, these control points are defined as the first control point and the second control point. A control command based on the control value is output under two different conditions.
That is, after the optimization calculation, ignoring changes in conditions that affect the plant, in addition to the first control point in which control is performed only in accordance with the control command based on the control value, and the control command based on the control value Then, it is divided into the second control points where the control is performed in consideration of the change of the conditions acting on the plant.
[0025]
As the first control point, it can be arbitrarily selected from the control points. For example, it is possible to select a control point not performing pressure control or a control point not performing power adjustment. Is possible.
In this embodiment, the first control is performed such that the output value output to the second control point is automatically determined from the result of the optimization calculation and the output value output to the first control point. Select point and second control point. That is, as the first control point, the control points SP42, SP44, SP45, SP46, SP47, SP48 of the boiler 11 and the boiler 12, the control point SP11 of the intermediate pressure steam circuit 20, the control point SP21 of the low pressure steam circuit 30, the gas turbine In addition to the control points S51, 52, 53 of the generator 52, the control points SP61, SP62, SP32 and the control point SP71 are selected.
Further, the remaining control points SP41, SP43, SP12, SP22, and SP31 are selected as the second control points.
[0026]
Next, an optimization operation control procedure in the plant having the above configuration will be described. In the control method of the present invention, first, modeling (numericalization) is performed for each utility system such as a boiler, a turbine, and a generator.
[Modeling of boilers 11 and 12]
The boilers 11 and 12 can be modeled by replacing them with linear or non-linear mathematical formulas, thereby making it possible to calculate the balance between fuel and steam generation, and using the optimal value search method corresponding to non-linearity to obtain the optimal operating values. Can do.
In the boiler formula, the type of fuel used in the boiler and the amount of heat necessary for the boiler to generate a unit amount of steam (the reciprocal number is described as “boiler unit” Unit is m³/ Kcal or kg / kcal) and a correction value for correcting the difference between the theoretical value and the actual value.
[0027]
That is, in a boiler using three different types of fuels A, B, and C as fuel, if the heat amounts of each fuel are α1, β1, and γ1, the steam generation amount (I) generated by one boiler per unit time is ,
I = (consumption amount of fuel A × α1 + consumption amount of fuel B × β1 + consumption amount of fuel C × γ1) × boiler basic unit + correction value
Can be expressed as
The amount of steam that can be used externally from the steam generated by the boiler
(Required steam amount (III)) is a value (III = I-II) obtained by subtracting the boiler self-consumption amount (II) from the boiler steam generation amount. Where self-consumption (II) is
II = I × α2 + β2 α2, β2: Boiler specific coefficients
Can be obtained.
[0028]
[Steam turbine modeling]
The modeling of the steam turbine can be obtained in consideration of the turbine output characteristics with respect to the steam consumption.
For example, in the case of non-linear output characteristics as shown in FIG. 2, the amount of electricity generated IV (1) between the valve points (1) to (2) is
IV ▲ 1 ▼ = Steam consumption²× α3 + steam consumption × β3 + correction value
The amount of electricity generated between valve points (2) to (3) IV (2)
IV ▲ 2 ▼ = Steam consumption²X α4 + Steam consumption x β4 + Correction value
The amount of electricity generation IV ▲ 3 ▼ above the valve point ▲ 3 ▼,
IV ▲ 3 ▼ = Steam consumption²X α5 + Steam consumption x β5 + Correction value
Can be obtained.
In the case of linear output characteristics, the proportionality coefficient is α5,
Electricity generated IV '= Steam consumption x α6 + Correction value
Can be obtained.
[0029]
Note that α3 to α6 and β3 to β5 are coefficients inherent to the steam turbine.
The correction value is a difference between a theoretical value and an actual value, and can be obtained in advance by an experiment or the like. For example, the correction value for the electricity generation amount IV (1) between the valve points (1) to (2) is
Correction value = (steam consumption²× α3 + steam consumption × β3) -actual electricity generation (measured value)
Can be obtained.
[0030]
[Modeling of gas turbine generator]
The numerical value of the gas turbine generator can be obtained based on the fuel consumption.
If the amount of electricity generated is V,
V = fuel consumption x α7 + β7 + correction value
It can obtain | require by the type | formula. Note that α7 and β7 in the equation are eigenvalues obtained from performance data and design data of the gas turbine generator.
As shown in FIG. 3, in the gas turbine generator, the maximum amount of electricity that can be generated varies depending on the outside air temperature and the consumption of steam that is supplementarily used to increase the output. Therefore, the maximum amount of electricity that can be generated by these factors is calculated, and this is set as a “constraint condition”. This constraint condition changes during the calculation as the steam consumption changes.
The maximum amount VI that can be generated is
VI = standard maximum amount−outside temperature × α8 + steam consumption for output increase × β8
Can be obtained. Here, the “standard maximum amount” means the maximum amount that can be generated when the outside air temperature is 0 ° C. and the steam consumption is 0, as shown in the graph of FIG.
[0031]
[Modeling of gas turbine waste heat recovery boiler]
The gas turbine waste heat recovery boiler recovers energy that was not used for power generation by the gas turbine generator. The difference between the supplied energy (fuel consumption) and the generated energy (electricity generation) Can be determined based on
And the steam generation amount VII generated by the gas turbine waste heat recovery boiler is
VII = Electricity generation (V) × α9 + fuel consumption × β9 + γ + correction value
Can be obtained. In the equation, γ is an eigenvalue obtained from performance data and design data of the gas turbine waste heat recovery boiler.
The correction value can be obtained based on the difference between the actual steam generation amount and the theoretical value of electricity generation amount (V) × α9 + fuel consumption amount × β9 + γ, and can be obtained by experiments or the like.
[0032]
[Modeling for the environment]
The amount of SOx generated is calculated from the sulfur content contained in the fuel consumed in each boiler.
For example, the SOx generation amount VIII of boiler A is
VIII = consumption of fuel A × sulfur content of fuel A + consumption of fuel B × sulfur content of fuel B + consumption of fuel C × sulfur content of fuel C
Can be obtained.
The total SOx generation amount of this plant is obtained by obtaining the SOx generation amount for each boiler and combining them. However, this SOx generation amount must not exceed the maximum processing capability of the SOx processing apparatus provided in this plant, and this maximum processing capability is set as a constraint value for the SOx generation amount.
[0033]
[Restrictions]
If the modeling is completed as described above, then the control constraint conditions in each utility system are set.
These constraints include inequality constraints where upper and lower limits are set based on the configuration and performance of equipment such as boilers, steam generators, and turbine generators, the balance between energy consumption and generated energy, and the amount of generated steam And the amount of steam consumed, and there are equality constraints based on the balance between the amount of generated power and the amount of consumed power.
[0034]
[Inequality constraints]
Inequality constraints include:
(1) Fuel consumption of boiler / gas turbine generator
(2) Electricity generation of steam / gas turbine generator
(However, as described above, the upper limit of the amount of electricity generated by the gas turbine generator is variable depending on the consumption of the steam for increasing the output)
(3) Steam consumption of steam turbine
(4) Boiler steam generation
(5) Steam conversion valve ventilation rate
(6) Amount of steam released to the atmosphere
(7) Restriction of steam retention prevention
(Since the flow of steam stops, the temperature drops, so a monitoring means for monitoring the flow of steam is installed in the place where the flow of steam in the supply line of high-pressure steam, medium-pressure steam, and low-pressure steam is likely to stay. (Set the upper and lower limits of the means.)
(8) Electric power flow restriction
This is a restriction on the amount of power flowing through this plant. An ammeter is provided at a predetermined position in the plant, and is set according to the capacity of electric equipment such as a transformer of the plant and a power transfer contract.
(9) Restriction on power purchase
It is set based on the contracted electricity usage of the power company.
(10) Environmental support restrictions
This is a restriction on the emission amount of substances that affect the environment, such as SOx, NOx, and CO2. Although these constraint values can be obtained by calculation, experiment, or the like, in many cases, these constraint values are preset in design.
[0035]
[Equal constraints]
▲ 1 ▼ Boiler energy balance
Ideally, the boiler uses all of the energy generated by the consumed fuel to generate steam.
Therefore, in the energy balance of the boiler,
Boiler steam generation (energy conversion value)-boiler fuel consumption (energy conversion value) = 0
And set.
(2) Balance of generation and consumption of high-pressure steam, medium-pressure steam, and low-pressure steam
Ideally, all of the steam generated by each boiler is used in a steam consuming device.
Therefore, in the generation and consumption balance of each steam,
Total amount of high-pressure steam generated-High-pressure steam consumption = 0
Total amount of medium-pressure steam generated-Medium-pressure steam consumption = 0
Total amount of low-pressure steam-Low-pressure steam consumption = 0
And set.
(3) Balance between generated energy and consumed energy
As for electricity, ideally, electricity generated by the generator and electricity supplied by the electric power company are all consumed in the plant.
Therefore, in the balance between the amount of generated power and the amount of power consumed,
Total amount of electricity generated + amount of electricity purchased-electricity consumption = 0
And set.
[0036]
[Objective (evaluation) function]
In this embodiment, the evaluation function minimizes costs such as boiler fuel costs, gas turbine fuel costs, electricity purchase costs, and environmental measures costs.
The boiler fuel cost and the gas turbine fuel cost can be obtained from the fuel consumption and the fuel unit price.
Further, the amount of power purchase can be obtained from the amount of power purchased and the unit price of power purchase.
Furthermore, the environmental measure cost can be obtained from the SOx generation amount and the SOx charge.
In the optimization calculation, a system operating condition that minimizes the evaluation function is searched while satisfying the above-described constraints.
[0037]
[Description of control block and control procedure]
Next, the configuration of the control device that optimizes the plant based on the above conditions and the procedure of processing by this control device will be described with reference to the block diagram of FIG. 4 and the flowchart of FIG.
The control system for executing the control method of the present invention performs optimization calculation for the entire plant, outputs a control command to the first control point, and results of optimization calculation ( And a second control unit 72 that outputs a control command to the second control point by applying a certain restriction to the control value.
[0038]
The first control unit 71 includes an operation condition determination unit 711 that determines an operation condition of each utility system (boilers 11 and 12, steam turbines 14 and 16, etc.) included in the plant. It has a condition setting unit 712 that sets conditions, a control output constraint calculation unit 713 that constrains the search range for optimization calculation within a predetermined range, and an optimization calculation unit 714 that performs optimization calculation.
The second control unit 72 includes a control point designating unit 721 that designates a second control point selected in advance, and a control value calculated by the optimization calculating unit 714 for the designated second control point. Output limit unit 722 that performs output by adding a certain restriction to the control value, and a power generation amount / power purchase amount calculation unit that calculates a power generation amount and a power purchase amount based on the output from the output limit unit 722 723 and a power purchase control unit 724 that controls power purchase amount.
[0039]
Further details of the processing procedure by the control system will be described with reference to FIGS.
Simultaneously with the start of operation (step S100), operation data and environmental data are collected from each utility system (step S101).
This data includes, for example, the supply amounts of fuels A, B, and C supplied to the boilers 11 and 12, the amount of steam generated by the boilers 11 and 12, the supply amount of fuel D supplied to the gas turbine generator 52, and the steam The power generation amount of the turbines 15, 17, 22, 24, 33 and the gas turbine generator 52, the supply amount of the fuel E supplied to the waste heat auxiliary boiler 51, the power amount supplied from the power company, and the like are included.
[0040]
Moreover, the measurement of elapsed time is started with a driving | operation start (step S102). When the preset first period (for example, 10 minutes) is up, the operation condition determination unit 711 of the first control unit 71 analyzes the data transmitted from the utility system and determines which one is used. It is determined which utility system is in operation and which utility system has stopped operating (step S103). Furthermore, the operating condition determination unit 711 determines whether optimization for each utility system is possible based on data from each control point, that is, whether a variable in the utility system model can be changed. (Step S104). If the variable cannot be changed, the value under the current operating condition is defined as a fixed value (step S105), and if the variable can be changed, it is defined as an operating variable (step S106).
[0041]
For example, in the boiler 11, when the supply amount of the fuel A can be changed and the supply amount of the fuel B and the fuel C cannot be changed, the supply amount of the fuel A is defined as an operation variable, and the fuel B The supply amount of fuel C is defined as a fixed value. Whether or not a variable in the model can be changed can be determined based on, for example, a preset constraint.
[0042]
Next, in the optimization calculation, the condition setting unit 712 always keeps the amount of steam and the amount of power supplied from the plant to the outside constant (step S107). The amount of steam supplied to the outside is the steam consumed by the steam turbines 14, 16, 21, 23, 32 in the plant from the total amount of steam generated by the boilers 11, 12 and the waste heat recovery auxiliary combustion boiler 51. Less consumption.
The amount of steam supplied to the outside for each of the high-pressure steam, medium-pressure steam, and low-pressure steam is assumed to be equal to the steam consumption of each steam consuming device CP11, CP12, CP13,

It is represented by
[0043]
Thus, in the calculation of optimization, it is on condition that there is no change in the consumption of each steam consumption device CP11, CP12, CP13 (step S107).
The supply amount CP14 of power supplied to the outside is the total amount of power generated in the plant plus the power purchase amount, but is assumed to be equal to the power consumption amount of the power consumption device CP14. The condition is that there is no change in the power consumption CP14 (step S107).
[0044]
Next, conditions necessary for calculating optimum values such as correction values, constraint values, and evaluation functions are read from a memory (not shown) (steps S109, S110, and S111).
The control output constraint calculation unit 713 sets a search range for optimization calculation in order to minimize the operation variation and execute the optimization calculation in a short time (step S111).
For example, the control output constraint calculation unit 713 sets a change range (search range) of the operation variable to ± 10% with respect to the current operation value, changes the variable within this range, and performs a small operation fluctuation. To perform optimization calculations.
[0045]
Thereafter, the optimum value calculation unit 714 calculates an optimum value (step S113). In this embodiment, since the evaluation function is set so as to minimize the costs of the fuels A to E and the power purchased from the power company and the environment, the optimization is possible, that is, the operation variable can be changed. For one control point, an optimal value that minimizes the cost is searched for while changing the variable in various ways (step S112). This optimization calculation can be executed using commercially available optimization software.
[0046]
After the optimization calculation is completed, a control point for transmitting each control value is designated (step 113), and whether the control point is a preset first control point or a second control point. Is determined (step S114).
If it is the first control point, the control value obtained by the optimization calculation by the optimization calculation unit 714 is limited (step S115) and output to each of the first control points (step S116). .
The output value to the second control point is automatically determined from the control value obtained by the optimization calculation and the control value of the first control point. If it is determined that the control point is the second control point, it is determined whether or not there has been a change in the operating condition of the plant after the optimization calculation (step S117), and there should be no change in the operating condition. For example, a control command is output based on the automatically determined control value (step S119).
[0047]
When there is a change in the operating condition, the control value obtained by the optimization calculation is changed according to the change in the operating condition (step S118), and the result is output as a control command. For example, when the vapor pressure of the high-pressure steam circuit 10 becomes low, the second amount of fuel A supplied to the boiler A is increased and the valve opening amount is increased in accordance with the decrease in the vapor pressure. A control command is output to control point SP43 and control point SP41 which are control points. It should be noted that the detection of fluctuations in operating conditions and the change of the control value accompanying this fluctuation detection may be performed finely at a constant period (second period) within the first period, for example, at intervals of 1 second. By doing in this way, the driving | running | working fluctuation | variation which generate | occur | produced after optimization calculation can be absorbed by a 2nd control point, controlling the whole utility system based on the result of optimization calculation.
[0048]
Moreover, as a restriction | limiting added to an above-described control value, for example, the control value obtained by optimization calculation is divided into 10 equal parts, and a control command is output. That is, when the optimization control value for a certain control point is 10, for example, when the first period is 10 minutes, the control amount per time is set to 1, and this control amount is set to 1 Output to the control point at minute intervals.
As described above, the reason why the control value output to the control point has a certain restriction is to minimize the operation fluctuation of the utility system.
[0049]
The power generation amount / power purchase amount calculation unit 723 calculates the necessary power generation amount and power purchase amount based on the operation data and environmental data collected from each utility system and the control value obtained by the optimization calculation unit 714. Is done.
At this time, the power generation / power purchase amount calculation unit 723 calculates a necessary power amount for the target power purchase amount obtained by the optimization calculation. That is, the power generation amount / power purchase amount calculation unit 723 indicates a shortage of power with respect to the target power purchase amount, and can be obtained by subtracting the target power purchase amount from the current power purchase amount. Then, using the obtained result as a control value, a control command is output to the control point SP71 which is the first control point. At this time, the control output is limited in the same manner as described above, and the obtained control value is divided into ten equal parts, for example, and a control command is output to the control point SP71.
In addition, the power purchase control unit 724 calculates the necessary amount of electric power and then calculates the necessary amount of the steam turbine 32 when the necessary amount of electric power increases as the operating condition changes. A control command is output to the second control point SP31 that controls driving. The detection of the change in the operating condition and the calculation of the necessary amount are performed, for example, every second.
As a result of the optimization calculation by the first control unit 71, when it is necessary to release the steam to the atmosphere, a control command is output to open the valve to the control point SP32 and the steam is released into the atmosphere.
[0050]
According to the above embodiment, the optimization calculation of the entire plant is performed in a short cycle of 10 minutes using the model formula, and the part of the utility system (first control point) constituting the plant is optimized. The control value that is the result of the calculation is assigned and a control command is output, and the other part (second control point) is controlled with the operating variables of the part of the utility system fixed. Since the control is decentralized, it is possible to absorb fluctuations in the operating conditions that occur after the optimization calculation in the other part, and to perform optimal control according to the operating conditions of the plant in a short time, and It can be done automatically.
[0051]
[Second Embodiment]
Operating conditions may change significantly due to changes in steam / power balance in optimization calculations. In this case, there is no problem as long as this state is maintained stably in a state where the state has changed greatly, but the operating condition may be restored to the original state (one time before) in the next calculation. In such a case, if operation is performed based on the calculation result after the change, a great amount of cost is wasted.
Therefore, in this embodiment, deviation check processing is performed to prevent wasteful generation of the plant as much as possible.
[0052]
FIG. 6 is a graph showing an optimization output value (solid line) when the deviation check is not performed and an optimization output value (two-dot chain line) when the deviation check is performed, and FIG. 7 shows the deviation check. It is a flowchart which shows the procedure of the process in the case of performing. In the graph of FIG. 6, the vertical axis represents optimization calculation output (control value output), and the horizontal axis represents time. In FIG. 7, the same steps as those in the flowchart of FIG. 5 are denoted by the same reference numerals, and the steps before step S112 and the steps after step 113 are not shown.
[0053]
After calculating the optimum value (step S112), the difference between the previous (one time before) calculation result and the current calculation result is obtained (step S121), and it is determined whether this difference is larger than a preset value. (Step S122). When this difference is smaller than a preset value, a control command is output to the designated control point (step S113).
[0054]
When this difference is larger than a preset value, it is determined that the deviation is large, and the operating variable is not changed by the obtained optimum value. That is, the control content based on the result obtained by the previous optimum value calculation is maintained.
This will be described with reference to the graph of FIG. 6. When calculating the optimum values indicated by reference symbols I and II, the difference between the previous optimal value calculation result and the current optimal value calculation result is S1 and S2. Yes, when the values of S1 and S2 are larger than a preset value, the previous operating condition is maintained (the maintenance state is indicated by symbols III and IV in the graph of FIG. 6).
[0055]
[Third embodiment]
In the third embodiment, medium pressure steam is minimized in order to maximize the amount of power generated in the plant while supplying the necessary steam amount to the steam consuming apparatus.
A block diagram of a control system for executing the control method of the third embodiment is shown in FIG.
In the third embodiment, in addition to the first control unit 71 and the second control unit 72 shown in FIG. 4, the third control as shown in FIG. A portion 73 is provided.
[0056]
The third control unit 73 includes an operation condition determination unit 731 that determines the operation condition of the utility system, a minimum pressure calculation unit 732 that calculates a minimum pressure, and a steam pressure control unit that secures a necessary amount of steam. 733.
The calculation of the minimum pressure of medium pressure steam is performed by fuzzy inference. The steps are shown in the flowchart of FIG.
[0057]
First, with the time-up of the first cycle (10-minute interval) (step S200), the vapor pressure of the intermediate-pressure vapor consumption device CP12 is detected (step S201). When there are a plurality of medium pressure steam consumption devices CP12, the steam pressure is detected for each.
Next, a difference ΔP between the vapor pressure lower limit value set in advance and the vapor pressure of each intermediate-pressure vapor consumption device CP12 is obtained (step S202). Among the plurality of intermediate pressure steam consumption devices CP12, a difference ΔP (in particular, described as PR) indicating the minimum value and an intermediate pressure steam consumption device CP12 (hereinafter referred to as the intermediate pressure steam consumption device) that detects the PR. Are described (step S203).
[0058]
Next, the pressure change of the intermediate pressure steam device CP12 (difference between the steam pressure detected last time and the steam pressure detected this time) is obtained (step S204), and any control point (control point SP21, SP22 in the plant) For example, SP21) is selected, and a pressure change is obtained for this control point (step S205). And the average value (DPR) of a pressure change is calculated | required about both (step S206).
Then, fuzzy inference is executed based on the above PR and DPR (step S207). The fuzzy control rules are as shown in the following table, and the membership function for fuzzy control is as shown in FIG.
[0059]
Note that an upper limit value and a lower limit value are set in advance in the fuzzy inference result (PP), and it is determined whether the inference result PP is within the upper and lower limit values (step S208).
If the result PP is within the above range, the fuzzy inference value is added to the current intermediate pressure above the target value (step S210), and a new target value is set (S211). When the result PP is out of the range, the upper limit value or the lower limit value is added to the current intermediate pressure above the target value (step S209), and a new target value is set (S211).
Thus, the process ends (step S212).
[0060]
[Table 1]

[0061]
The control based on this fuzzy inference gives priority to the pressure recovery direction, and when the pressure is lowered, it is slowly lowered, and when it is raised, it is rapidly raised.
The steam pressure control unit 733 controls the steam amounts of high-pressure steam, medium-pressure steam, and low-pressure steam at a cycle of about 1 second to ensure the steam amount required by the steam consuming device.
The control point value of the high-pressure steam is fixed at a constant pressure (1850 pounds), and the amount of steam generated is adjusted by the boilers 11 and 12. The vapor pressure is detected by a high-pressure steam sensor, and steam is generated by controlling the fuel so that it becomes a specified pressure. The control points in this case are SP43 to SP48, and the fuel to be used is designated by the first control unit 71 (see FIG. 4) that performs the optimum steam / power balance calculation.
[0062]
The control point for medium pressure steam is the previously determined steam pressure (around 300 pounds).
The control points are the control points SP11 and SP12 in FIG. 1, and the steam pressure is detected by an intermediate pressure steam sensor and controlled to a specified pressure.
The low pressure steam control point is fixed at a constant pressure (50 pounds). The control points are SP21 and SP22, and the steam pressure is detected by a low-pressure steam sensor and controlled to a specified pressure.
[0063]
Although the preferred embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.
For example, the plant to which the present invention is applied is not limited to that described above, and can be applied to other plants having a plurality of utility systems.
Although the second control point has been described as being limited to the control points of the utility system that have a large impact on the plant operating cost, other utilities, for example, utilities that have a significant impact on the environment. A second control point may be selected from the system control points.
Further, in the above third embodiment, the medium pressure steam is changed within the allowable range, but the change of the vapor pressure within the allowable range is either high pressure steam or low pressure steam. Also good.
[0064]
【The invention's effect】
Thus, according to the present invention, the control point in the plant is divided into the first control point and the second control point, and control based on the result of the optimization calculation is performed at one control point, and the other control point is controlled. Since the role is shared to control the changes in operating conditions that occur after optimization calculation at the point, it is possible to perform optimization control corresponding to subtle changes in operating conditions in a short time. In addition, the utility system can be quickly controlled with a change in operating conditions with a simple computer system.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an example of a plant to which a control method of the present invention is applied.
FIG. 2 is a graph showing output characteristics of a steam turbine.
FIG. 3 is a graph showing output characteristics of a gas turbine generator.
FIG. 4 is a block diagram showing a configuration of a control system that optimizes a plant.
FIG. 5 is a flowchart showing a processing procedure by the control system of FIG. 4;
FIG. 6 shows an optimization output value (solid line) when the deviation check is not performed and an optimization output value (two-dot chain line) when the deviation check is performed according to the second embodiment of the present invention. It is a graph which shows.
FIG. 7 is a flowchart illustrating a processing procedure when a deviation check is performed.
FIG. 8 is a block diagram of a control system according to a third embodiment of the present invention, which executes the control method of this embodiment.
FIG. 9 is a flowchart showing a procedure for obtaining a minimum pressure of medium-pressure steam according to the third embodiment of the present invention.
FIG. 10 is a diagram illustrating a membership function for fuzzy control.
[Explanation of symbols]
10 High-pressure steam circuit
11,12 boiler
13 Pressure gauge
14,16 High-pressure steam turbine
15, 17 Generator
18 Pressure gauge
20 Medium pressure steam circuit
21,23 Medium pressure steam turbine
22,24 Generator
25 Pressure gauge
30 Low pressure steam circuit
31 Vapor discharge part
32 Low pressure steam turbine
33 Generator
40 Power supply circuit
41 Electric power company
42 Ammeter
51 Waste heat recovery auxiliary combustion boiler

Claims (10)

In a plant having a plurality of utility systems including at least a steam generator and a power generator, a method of controlling the utility system so that the plant can be operated in an optimum state,
Creating a pre- formulated model for each of the utility systems;
Presetting control points to be controlled for each of the utility systems;
Collecting operational data from the plant;
Determining whether or not the driving condition can be changed for the utility system in a first period based on the collected driving data;
For each of the utility systems determined to be capable of changing operating conditions, changing variables in the model and performing optimization calculations for optimal operation of the plant;
A step of selecting a first control point from the control points according to a preset procedure and setting a control point other than the first control point as a second control point;
Outputting a control command to the first control point and the second control point based on the result of the optimization calculation;
Outputting a control command so as to absorb a change in operating conditions generated in the plant in the second cycle set in the first cycle with respect to the second control point;
Have
At least one of the first control point and the second control point, a control value obtained as a result of the optimization calculation is applied a plurality of times within the corresponding first period or second period, respectively. The utility system control method is characterized in that output is divided into two . One utility system is provided with a plurality of control points for supplying fuel, and one control point of the plurality of control points is either the first control point or the second control point, and the other 2. The utility system control method according to claim 1 , wherein the control point is the remaining first control point or the second control point . The control values output in a plurality of times are output at equal intervals, and substantially the same control amount is set for each output timing until the control value obtained as a result of the optimization calculation is obtained. 3. The utility system control method according to claim 1 , wherein an accumulated control value is output . Changes in variables in the model, with reference to the measured value obtained from the operation data, any one of claims 1 to 3 you and performing in a range having an upper limit and / or the lower limit value A method for controlling the utility system described in 1. The method further includes a step of comparing the calculation result of the current optimization with the calculation result of the previous optimization, and when the difference between the two is larger than a preset value, the operating condition of the utility system is changed. The service system control method according to claim 1 , wherein the service system is temporarily suspended. The plant is provided between a plurality of steam supply lines having different steam pressures, the steam supply line on the high-pressure side and the steam supply line on the low-pressure side, and the steam supplied from the steam supply line on the high-pressure side In the case of having a utility system that is operated and supplies steam with reduced pressure to the steam supply line on the low pressure side,
At least one of the vapor pressure of the high pressure side and low pressure side, as may be modified within the scope of variation in the pressure supply to the outside is allowed, more of claims 1-5, characterized in that the calculation of optimization A method for controlling the utility system according to claim 1. A step of detecting the vapor pressure on the low pressure side or the high pressure side , a step of obtaining a difference between the detected vapor pressure and a lower limit value of the allowable vapor pressure, and based on this difference, the low pressure side by fuzzy inference or control method of the utilities system according to claim 6, characterized in that it comprises the steps of determining the pressure of the high-pressure side steam. 7. The utility system control method according to claim 6 , wherein the steam is released by opening the low-pressure side steam supply line to the atmosphere based on the result of the optimization calculation. In the case where the plant has an auxiliary utilities system, according to any one of claims 1 to 8 this for auxiliary utilities systems create the model, characterized in that considered in the optimization calculation To control the utility system. The method according to claim 9 , wherein the auxiliary utility system is a gas turbine generator to which steam is supplied as auxiliary power from the plant.

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