JP2683738B2 - Plant operating condition evaluation method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for evaluating the operating state of a plant such as a power plant, and more particularly to a method for detecting a plant having a certain causal relationship between process amounts. The present invention relates to a plant operation state evaluation method that considers the reliability of the process amount. [Prior Art] As described in Japanese Patent Application Laid-Open No. 56-85506, a conventional apparatus has a process amount reference value that should be as described above (a fixed function set based on a plant load). When,
The measured process amounts were compared and the difference in the process detected amount was determined based on the difference. Further, in Japanese Patent Laid-Open No. 59-154320, a dynamic model of a plant is provided, an expected process amount is obtained using this dynamic model, and this is compared with an actually measured process amount to determine an abnormal process detection amount. An example of doing so is described. [Problems to be Solved by the Invention] In the above conventional technology, the operating method of the plant is changed, or the characteristics of the plant are different. When the state of the plant changes temporarily or over time, the process amount reference value based on the preset plant load is
A large deviation from the reference value in actual operation occurs, and therefore, despite normal operation, it is determined that the process amount is abnormal based on the comparison between the preset process amount reference value and the measured value. There was a problem. In addition, in order to make an abnormality determination using a dynamic model, a complicated simulation model is required, and there is a problem in economic efficiency due to the enormous number of devices. An object of the present invention is to evaluate the operating state of a plant economically and always in a plant-like operating state. [Means for Solving Problems] The above problem is in a plant operating state evaluation method for evaluating the operating state of a plant based on the process amount while detecting the process amount by a process detector group. This is achieved by a plant operating state evaluation method characterized by making a comprehensive judgment based on the mutual causal relationship between the respective process quantities characterized by the above configuration to judge whether or not there is an abnormality in the detected process quantity. In addition, while detecting the process amount by the process detector group, in a plant operating state evaluation method for evaluating the operating state of the plant based on the process amount, between each process amount characterized by the configuration of the plant Determine whether there is an abnormality in the detected process amount by making a comprehensive judgment based on mutual causal relationships, and when an abnormal process amount is detected, obtain a normal predicted value and replace it with the abnormal process amount to determine the operating state of the plant. This is achieved by a plant operation state evaluation method characterized by evaluation. [Operation] In plants such as power generation plants, fluids such as steam, water, fuel, electricity, and gas are flowing, and these perform predetermined functions in the equipment that constitutes the plant to exert the performance of the plant. There is. Therefore, the process quantity of the plant is the state quantity of these fluids flowing to the plant, or the state quantity of the equipment itself, such as the metal temperature of the equipment. Among these process quantities, there are certain relationships between the upstream and downstream of the fluid flow, specific relationships due to thermal or chemical reactions in the equipment making up the plant, and temporal changes in the process quantities. Has a fixed relationship with a temporal change relationship that changes based on a certain index, and a process quantity characteristic relationship that the process quantity changes only within a limited range from the plant configuration. . While detecting the process amount, the causal relationship between such process amounts is comprehensively evaluated based on the detected process amount. Therefore, when an abnormal process amount occurs, the abnormal process amount It is detected based on the peripheral process amount. Further, when the abnormal process amount is detected, the abnormal process amount is replaced with the normal predicted value, and the operating state of the plant is evaluated based on the replaced value. [Examples] Hereinafter, the present invention will be described by taking a thermal power plant as an example. FIG. 6 is a diagram showing an outline of a thermal power plant. In FIG. 6, the steam generated in the boiler 1 passes through the main steam breaker 18 and enters the high pressure turbine 2, where a part of the thermal energy of the steam is converted into rotary mechanical energy for rotating the generator 4. The steam that has worked in the high-pressure turbine 2 passes through the low-temperature reheat steam pipe 19, is reheated in the reheater 16, is guided to the reheat turbine 3 through the high-temperature reheat steam pipe 20, and performs the work again. The steam that has worked in the reheat turbine 3 enters the condenser 5 as exhaust gas, is cooled by cooling water such as seawater, and is restored to water. This ascites is pumped up by the ascites pump 6, and heat is recovered through each heat exchanger of the ascites heat exchanger 7, the air extractor 8 and the gland condenser 9, and the temperature is reduced by the low pressure feed water heater 10 and the deaerator 11. The ascitic fluid that has been raised and pressurized by the boiler feed water pump 12 is further heated by the high-pressure feed water heater 13 as boiler feed water, and passes through the main water supply pipe 21 to feed the boiler 1
Water is supplied to The high-pressure feed water heater 13, the deaerator 11, and the low-pressure feed water heater 10 are all heated by the extraction air of the turbine.
In the boiler 1, the fuel controlled by the fuel control valve 17 passes through the fuel burner 14 and burns in the furnace. The water supply receives the radiant heat from this combustion to become steam, and the superheater 15
Is overheated and sent to the turbine. In such a plant, FIG. 7 shows an example of the state quantity of each part when the plant is operating in a normal state. Fig. 7
It shows the normal operating state of a plant generating 500 MW, and shows the temperature, pressure, and flow rate in each part of the boiler, turbine, auxiliary machinery, and so on. The state quantity shown here is a process quantity that can be easily measured. In FIG. 7, it can be seen that the process amounts have the following characteristic relationships. (1) There is an upstream / downstream relationship in the process flow. That is, the flow rate is equal from the upstream side to the downstream side, the pressure is large on the upstream side and low on the downstream side, and the temperature does not become higher than the upstream side if there is no heat exchanger in the middle. (2) The processes around the turbine and the heat exchanger have a thermodynamic relationship based on the device characteristics. For example, if the inside of the equipment is in a saturated state, the process amount of pressure and temperature inside the equipment are in a saturated relationship, that the heating amount and the amount to be heated in the heat exchanger are equivalent, the extraction stage pressure of the turbine is It is proportional to the amount of steam passing through it. (3) The process amount of the plant changes temporally with the operation of the plant, but the change is the same as the change of the generator output, the change with the change of the main steam pressure, etc. Inevitably, it follows and changes according to an index. (4) The process amount of the plant changes only within a limited range due to the plant configuration. (5) Even if there is a process amount that makes a special motion that is not included in the above (1) to (4), the motion necessarily has a specific relational expression. The point of the present invention is to determine the abnormality in the process amount detection by combining the above relationships (1) to (5) and making a comprehensive evaluation. Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows that a process amount of a plant is input to a process signal processing unit 100, and an input signal exchanged into an engineering unit is used as a process hydrodynamic relation diagnosis unit 101, a process thermodynamic relation diagnosis unit 102, and a process time. Input to each of the physical relationship diagnosis unit 103, the process signal characteristic diagnosis unit 104, and the process special relationship diagnosis unit 105, and based on the information diagnosed by these diagnosis units, the process state comprehensive diagnosis unit 106 correlates ( The functional configuration of the device for comprehensively diagnosing (mutual causal relationship) and determining whether the process amount is normal or abnormal is shown. Incidentally, if the process configuration of the plant, or the range of the process amount for performing the abnormality determination is limited, not all of the diagnostic units 101, 102, 103, 104, 105 are necessary, and some of these diagnostic units may be combined. . As an example of comprehensively diagnosing a process state with the functions of the diagnosis units 101, 102, 103, 104 shown in FIG. 1 and determining an abnormal process amount, a method for evaluating the process state around the high pressure turbine shown in FIG. 2 will be described in detail below. . FIG. 2 shows a process system diagram around the high-pressure turbine 2. Turbine inlet steam (pressure P ₀ , temperature
T ₀ ) enters the high-pressure turbine 2 through the regulator valve 22 and expands. The expanded steam is extracted in the first extraction stage, and the extracted steam (pressure P ₁ , temperature T ₁ ) is used by the NO.1HP heater 23 for heating boiler feed water. The exhaust steam (pressure P ₂ , temperature T ₂ ) of the high-pressure turbine 2 is sent to the boiler 1 and reheated, but a part of the steam is extracted for heating the boiler feed water in the NO.2 HP heater 24. Here, the state of expansion of steam in the high-pressure turbine 2 is represented as shown in FIG. 3, and the process amount required to obtain the efficiency ηHP inside the high-pressure turbine is as shown in FIG. 4 points. (I) Turbine inlet steam pressure (P ₀ ) (II) Turbine inlet steam temperature (T ₀ ) (III) Turbine exhaust pressure (P ₂ ) (IV) Turbine exhaust temperature (T ₂ ) As shown in FIG. 4, there are the following process quantities around the high-pressure turbine that have a strong causal relationship with these process quantities. (I) Boiler outlet steam pressure (P _0B ) (II) Boiler outlet steam temperature (T _0B ) (III) NO.1HP heater body pressure (P _1H ) (IV) NO.2HP heater body pressure (P _2H ) (V) ) Reheater inlet steam pressure (P _2R ) (VI) Reheater inlet steam temperature (T _2R ) (VII) Control valve opening (P _0S ) (VIII) Main steam flow rate (calculated value) (F _0B ) ( (IX) Turbine extraction pressure (P ₁ ) (X) Turbine extraction temperature (T ₁ ) High-pressure turbine stage Process quantities for internal efficiency calculation and these process quantities around the turbine are as follows. I have a relationship. (A) Relationship between upstream and downstream (a) P _0B and P ₀ (b) T _0B and T ₀ (c) P ₁ and P _1H (d) P ₂ and P _2H , P ₂ and P _2R (e) T ₂ and T _2R (b) Thermodynamic relationship (a) P ₁ and P ₂ (b) P ₀ and T ₀ , F _0B and P _0S (c) Relationship between temporal changes (a) F _0B and P ₁ Change the same. (B) F _0B and P ₂ change the same. (C) P ₁ and P ₂ change the same. (D) P ₁ and P _1H change the same. (E) P ₂ and P _2H change the same. (F) P ₂ and P _{2 R} change the same. (G) The temperature does not change rapidly as a thermal change. (D) Characteristics of detector error The detector has some error, but this variation has a certain width and does not change abruptly. First, in the upstream and downstream relationships of the item (a) related to the process in the hydrodynamic relationship diagnosis unit 101 of the process, the following relational expressions are established. P _0B = P ₀ + ΔP ₀ P ₁ = P _1H + ΔP _1H P ₂ = P _2H + ΔP _2H P ₂ = P _2R + ΔP _2R where ΔP ₀ , ΔP _1H , ΔP _2H and ΔP _2R are pressures in each process line The amount of drop, which is proportional to the square of the flow rate flowing there. In addition, T _0B = T ₀ + ΔT ₀ T ₂ = T _2R + ΔT _2R where ΔT ₀ and ΔT _2R are the temperature drop in each process line, which is due to heat radiation to the outside air,
It is almost constant. Next, in the thermodynamic relation of the item (b) related to the thermodynamic relation diagnosis unit 102 of the process, the following relational expression holds. P _OS = f (F _OS , P ₀ , T ₀ ) Next, the following relational expression is established in the relation of the time change of the term (c) related to the temporal diagnosis unit 103 of the process. Here, N is a suffix and indicates OB, 0,1,2,2R.
α and β are constants. In the characteristic of the detector error of the item (d) related to the characteristic diagnostic unit 104 of the process signal, the following relational expression holds. Here, r is a constant and has a value _unique to each of the process quantities P _0B , P ₁ , ... FIG. 5 shows a state evaluation of the process amount P ₂ detected by the pressure gauge by the above-mentioned relational expression. In FIG. 5, the hydrodynamic relationship diagnosis unit 10 of the process is shown.
If the relationship between P ₂ and P _2H and P ₂ and P _2R in 1 is normal, it changes within the permissible width (shaded area, the same below) in each relationship curve, but P ₂ and P _2H Therefore, if there is an abnormal value in the process amount of P _2R , this relational expression will collapse and deviate from the allowable range. Similarly, in the process thermodynamic relationship diagnosis unit 102, it is checked whether P ₂ / P ₁ is within a certain allowable width, and in the process time relationship diagnosis unit 103, the time change of P ₂ and P ₁ , P _2H , P _2R temporal correlation is checked,
Further, in the characteristic diagnosing unit 104 of the process signal, in order to diagnose the operation as the detector, it is checked whether the changing speed of P ₂ is within the allowable value. As a result of checking in each diagnostic unit, if there is something that deviates from the allowable value, an abnormal signal to the process status comprehensive diagnostic unit (a signal that turns ON due to an abnormality)
Is transmitted. In the process state comprehensive diagnosis section, when the abnormal signals from these diagnosis sections are inputted, the judgment logic based on the correlation of each signal (the process amount is judged to be abnormal due to the occurrence of two or more abnormalities from each diagnosis section) The presence or absence of an abnormality in the process amount P ₂ is determined by the following, and in the case of an abnormality, the signal 201 is output, and at the same time, the normal predicted value request signal 202 is output to obtain the normal predicted value from the related relational expression ( The relational expression of P ₂ / P ₁ ) and the predicted value P ₂ ′ 203 are input to the process signal processing unit, P ₂ is replaced with P ₂ ′, and the process amount of the plant is also evaluated. Although FIG. 5 shows the abnormality diagnosis of the process amount P ₂ , other process amounts are also detected by the same method. As shown in Fig. 5 above, by simple logic,
The state quantity of the process quantity can be easily evaluated with the same accuracy as that of the complex dynamic simulation model. Although FIG. 5 describes an example without the special relation diagnosis unit 105 of FIG. 1, an example having the function of the special relation diagnosis unit 105 of FIG. 1 will be described below as another embodiment of the present invention. explain. In Fig. 4, turbine inlet steam pressure P ₀ , temperature T
_A constant relationship should be maintained between ₀ and the turbine extraction pressure P ₁ , temperature T ₁ and turbine exhaust pressure P ₂ , temperature T ₂ due to the expansion characteristics of steam when the turbine is functioning normally. However, when the turbine deviates from the normal state, the above relationship is broken and a special movement occurs. The following relationship holds for this special movement. P ₀ P ₁ , T ₀ T ₁ P ₁ P ₂ , T ₁ T _2, that is, the fact that turbine extraction and exhaust conditions never exceed the turbine inlet steam conditions. In addition, the equipment and piping are designed and manufactured under predetermined design pressure and temperature conditions, and there is an operating condition that operation above this design pressure and temperature must never be applied. P _0D P ₀ , T _0D T ₀ P _1D P ₁ , T _1D T ₁ P _2D P ₂ , T _2D T ₂ Here, D in the suffix indicates a design condition. Also,
When the opening P _0S of the turbine control valve 22 is fully closed, P ₁ and P ₂ show the same value. P ₁ = P ₂ (when P _0S = 0) In addition, a check valve for backflow prevention is provided in the extraction pipe from the high-pressure turbine to the HP heater so that the fluid does not flow back from the HP heater to the turbine. However, when this check valve for backflow prevention malfunctions, P _1H P ₁ , (when the check valve of NO.1HP heater bleed air fails) P _2H P ₂ (when the check valve of NO.2HP heater bleed air fails) There may be cases. Above, the relations when the operation of the turbine deviates from the normal state and it is operated under special conditions are listed.These relational expressions are qualitative, know-how obtained from operating experience of the plant, fragmentary Most of them belong to so-called knowledge information. The determination based on knowledge information that is not limited to such mathematical expressions is a function of the special relationship diagnosis unit 105. If the function of the special relation diagnosis unit based on the knowledge information described above is added to the evaluation logic of FIG. 5 and provided for the judgment condition of the built-in diagnosis evaluation, the plant equipment is not limited to the normal state, The process state quantity can be accurately evaluated for all operating states of the plant, and further effects can be exhibited. [Effects of the Invention] According to the present invention, without providing a complicated plant simulation model, a simple method can be applied to any operation of the plant, and also secular change or characteristic change (performance change, etc.) of the plant. ), The abnormal process amount of the plant is determined, and if the process amount is not detected normally, calculate the normal predicted value and replace it with the abnormal detected value to evaluate the operating state of the plant. Therefore, the operating state is not evaluated based on the inaccurate process amount, and the reliability of the operating state evaluation is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the function of one embodiment of the present invention, FIG. 2 is a system diagram showing the names of process quantities around a turbine, and FIG. 3 is a turbine. FIG. 4 is a characteristic diagram showing an example of internal vapor expansion, FIG. 4 is a system diagram showing names of process quantities around a turbine, and FIG. 5 shows a part of the function of the embodiment shown in FIG. It is a block diagram shown, FIG. 6 is a system diagram showing an example of an outline of a thermal power plant, and FIG. 7 is a system diagram showing an example of a process amount of the thermal power plant.

Claims (1)

(57) [Claims] A method for evaluating a plant operation state in which a process amount is detected by a process detection device group and the plant operation state is evaluated based on the process amount, characterized by the configuration of the plant, between an upstream and a downstream of a fluid flow. Inter-causal relations of process quantities in plants, thermodynamic inter-causal relations of process quantities based on the characteristics of the equipment that composes the plant, temporal inter-causal relations in which time-dependent changes in process quantities follow certain prescribed indexes, Whether there is an abnormality in the detected process amount by judging from the mutual causal relation that the amount changes within a limited range from the plant configuration, and the mutual causal relation between each process amount including any one of A method for evaluating a plant operating condition, which comprises: 2. The plant operating state evaluation method according to claim 1, wherein when an abnormal process amount is detected, a normal predicted value is obtained and replaced with the abnormal process amount to evaluate the operating state of the plant. Operating condition evaluation method.