CN110080833B - Method for evaluating frequency modulation capability of high-speed governing valve of steam turbine for improving peak shaving of unit - Google Patents
Method for evaluating frequency modulation capability of high-speed governing valve of steam turbine for improving peak shaving of unit Download PDFInfo
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Abstract
The invention discloses an evaluation method for improving the frequency modulation capability of a turbine high-speed governor of a set peak shaving, which comprises the steps of collecting DCS data of the pressure behind a valve when the valve opening degree of each high-speed governor of the set is from 0 to full opening; calculating the steam flow of each high-pressure regulating valve at different valve opening degrees; drawing a relation curve between the valve opening and the steam flow according to the valve opening of each high-pressure regulating valve of the unit and the calculated steam flow of each high-pressure regulating valve at different valve openings, matching the drawn relation curve with a factory design relation curve, obtaining a difference absolute value by subtracting data of any two adjacent moments in collected DCS data of the pressure behind the valve, judging whether the value of the | Delta P | is in an interval [0, Delta Pmax ], and judging that the high-pressure regulating valve has a hardware fault when the value of the | Delta P | exceeds the interval. The method carries out fault early warning on unit load sudden change based on pressure monitoring behind the high-speed governor valve, realizes real-time evaluation of the frequency modulation capability of the high-speed governor valve of the steam turbine, and improves the peak modulation performance of the unit.
Description
Technical Field
The invention relates to the field of power grid dispatching communication, in particular to an evaluation method for improving the frequency modulation capability of a high regulating valve of a steam turbine for unit peak shaving.
Background
At present, the country strongly supports the development of new energy, and in order to enable a new energy power system to supply stably and reliably, more and more thermal power generating units (even heat supply units) with large power stabilize instability brought to a power grid by new energy such as wind power and the like by participating in deep fast peak shaving. When a plurality of large thermal generator set turbines are put into an AGC operation mode to participate in peak shaving, load sudden-change faults often occur, and the safe and efficient operation of the units is seriously influenced. Generally, there are many factors causing sudden load failure of a steam turbine in practice, and from published literature, the most cases of sudden load failure of the steam turbine in the sequence valve operation mode are caused particularly due to software and hardware problems of a high pressure regulating valve (generally referred to as a "high regulating valve" for short and indicated by a symbol "GV"). The load sudden-change fault of the unit, which is caused by the mismatching of the flow characteristic design curve of the high-speed regulating valve and the actual flow characteristic, belongs to the software fault of the high-speed regulating valve and is the most common fault at present; in addition, the high-speed governor involved in load regulation frequently acts, so that the reliability of the driving connecting piece is seriously tested, and the failure rate is increased due to the increase of hardware abrasion. When the high-speed regulating valve has hardware connection faults, the steam turbine generates load sudden change, oscillation and the like in the sequence valve operation mode to influence the frequency modulation function of the unit. This is attributed to a turnstile hardware fault that occurs only second in frequency to a software fault. In order to solve such failures, many researchers have described the mechanism of the sudden load failure caused by the high-speed gate problem and proposed some effective solutions. For example, in the aspect of software faults, an online monitoring system of flow characteristics is designed for deviation early warning of a high-speed governor flow characteristic curve, and in the aspect of hardware, an effective diagnosis method based on a high-speed governor switch test is also provided, so that the faults can be rapidly tested and diagnosed, and the types and reasons of the faults can be effectively judged. These measures have all achieved good results in practical use. However, the existing hardware fault diagnosis method for the high-speed gate has certain limitation, the existing measures are to analyze and judge the fault reason after the fault occurs, and for the problems of fault early warning and unit frequency modulation capability evaluation required by an actual intelligent power plant, the method has the defect of timeliness, cannot give early warning when the fault occurs or is about to occur, cannot give fault prompt when the unit is in a peak modulation mode, and has a non-obvious effect on improving the unit frequency modulation capability. In addition, these measures also require special tests to verify, take up the running time of the plant, and the test data requires professional technicians to analyze and process, which also takes a considerable amount of time. Therefore, the timely and effective method for evaluating the frequency modulation capability of the high-speed governor has great significance for improving the frequency modulation performance of the unit, improving the safe operation performance of the unit and the like.
The existing high-pressure regulating gate fault diagnosis means is to accurately analyze data collected by DCS, and key data parameters comprise high regulating gate opening, unit power, comprehensive flow instructions, main steam pressure, regulating stage back pressure, high exhaust pressure, main steam temperature, high exhaust temperature, regulating stage back temperature, # 1- # 3W temperature, vibration X/Y, EH oil pressure and the like. Finally, an actual flow rate (%) calculation is performed based on the fledgarel formula to determine whether or not there is a failure. The parameters can reflect the running state of the high-speed regulating valve, but the pressure is taken as a key characterization parameter of the valve, and the pressure measuring point of the existing valve is only arranged in front of the valve and is not arranged behind the valve, so that the state monitoring of the valve can be perfected by increasing the pressure measuring point behind the valve; when the internal structural components of the valve are abnormal, the pressure before the valve is basically unchanged, but the pressure after the valve is changed. Therefore, from the basic principle of the internal flow field of the valve, increasing the pressure measuring point behind the valve is a feasible way for evaluating the frequency modulation capability of the valve in real time.
In general, as shown in fig. 1, in the section represented by curve 1, the valve opening is relatively small, the steam flow passing through the valve hardly changes, the pressure change after the high-pressure valve in the section is not large, the pressure difference after the high-pressure valve between adjacent times is negligible, but the pressure difference before the high-pressure valve is in the maximum state. In the interval shown in curve 2, the valve opening is linear with the steam flow. At this time, the steam flow increases with the increase of the valve opening, the pressure behind the high-pressure regulating valve continuously decreases, the pressure difference value behind the high-pressure regulating valve between adjacent moments is in a maximum value state, and the pressure behind the front valve of the high-pressure regulating valve gradually decreases. As the valve opening is further increased, a non-linear relationship between the valve opening and the steam flow is present, as shown in curve 3. In the interval, the steam flow gradually becomes gentle along with the increase of the opening degree, the trend that the pressure difference value before and after the high-pressure regulating valve becomes small is weakened, and the pressure difference value after the valve between adjacent moments is reduced. In the section represented by the curve 4, the steam flow does not change along with the change of the valve opening, the pressure difference between the front valve and the rear valve of the high-pressure regulating valve is close to 0, and the pressure difference between the rear valves at adjacent moments is also close to 0. When the high-pressure regulating valve has hardware faults, for example, the connecting parts such as a valve rod nut of the high-pressure regulating valve are worn to cause the faults such as tripping, loosening and even falling of the connecting parts of the valve head, and the valve rod is lifted according to a given instruction, but the valve head can generate a sudden change phenomenon of the opening of the high-pressure regulating valve (as shown in figure 2) under the action of airflow force generated by steam pressure and the self gravity of the valve head, so that the load of a unit is suddenly changed, and the pressure difference value of the high-pressure regulating valve between adjacent moments of the valve rod is larger than the maximum value of the high-pressure regulating valve in normal operation. According to the technical principle, the hardware fault early warning function of the high-speed regulating valve can be realized.
Disclosure of Invention
The invention mainly aims to provide an evaluation method for improving the frequency modulation capability of a high-speed governing valve of a steam turbine, which aims to overcome the problems.
In order to achieve the above object, the present invention provides a method for evaluating the frequency modulation capability of a turbine high-speed governor for improving the peak shaving of a unit, which comprises the following steps:
s10, collecting DCS data of pressure after the valve of each high-pressure regulating valve of the unit from 0 to full opening when the unit is in a normal load operation state;
s20, setting the normal operation of the unit, and calculating the steam flow of each high-pressure regulating valve at different valve opening degrees;
s30, drawing a relation curve of the valve opening and the steam flow according to the valve opening of each high-pressure regulating valve of the unit and the calculated steam flow of each high-pressure regulating valve at different valve openings, wherein the drawn relation curve is matched with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, the next step is carried out;
s40 obtaining absolute difference values by subtracting data of any two adjacent moments in collected DCS data of pressure behind the valve, and selecting the maximum absolute difference value from the obtained absolute difference values to define the maximum absolute difference value as delta P'maxOf selected Δ P'maxMultiplying by a factor K, K>1, obtaining the maximum value DeltaPmax,I.e. by
ΔPmax＝KΔP’max(MPa), the minimum value of the absolute value of the pressure difference value after the valve between adjacent moments is 0, and the value range of the absolute value of the pressure difference value after the valve is obtained is [0, delta P ]max]Namely;
|ΔP|＝|Pn+1-Pn| (MPa)；
s50, if the pressure data after the valve collected by the unit at a certain time Tn is Pn, and the pressure data after the valve collected at the next time Tn +1 is Pn +1, the absolute value of the pressure variation in the period is:
|ΔP|＝|Pn+1-Pn|(MPa) (2)，
whether the value of | Δ P | is within the interval [0, Δ Pmax ] is judged, and when the value of | Δ P | exceeds the interval, it is judged that the hardware fault exists in the high-speed regulation gate.
Preferably, the S30 includes:
s301, under the condition that the unit is in a load operation state, switching the operation mode from a sequence valve to a single valve according to the operation regulation of the unit, and increasing the load of the unit to 95% on the basis;
s302, removing the coordination control and the automatic sliding pressure operation control of the unit, reducing the main steam pressure of the unit and increasing the comprehensive valve position instruction of the unit on the basis of keeping the load of the unit basically unchanged, so that the high regulating valve of the unit is in a fully open state, and determining the high regulating valve as a software fault reason or a hardware fault reason according to whether the load mutation phenomenon occurs in the process;
s303, respectively carrying out two-valve full-opening and three-valve full-opening tests of at least two groups by taking diagonal steam admission as a two-valve steam admission mode, and verifying the fault reason determined in S202 according to whether a load sudden change phenomenon occurs in the process;
s304, collecting data for configuration and continuous recording in the DCS, wherein the collection time interval is within 1S, calculating the flow characteristic of the high-speed regulating valve by using the collected related data through a Friedel formula, obtaining the hardware fault characteristics, and judging the hardware fault and the severity of the valve, wherein the Friedel formula is as follows;
wherein G is rated flow; g' is the variable working condition flow; p is a radical of1Is the rated main steam pressure; p is a radical of2To regulate post-stage pressure; p is a radical of1The main steam pressure under variable working conditions; p is a radical of2' is the pressure after the regulating stage when the working condition is changed; t is t1Is the rated main steam temperature; t is t1The main steam temperature is under variable working conditions;
s305, drawing a relation curve of the actual flow of the high-speed regulating valve and the opening degree of the valve according to the calculated actual flow, matching the drawn relation curve with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, entering the next step.
Preferably, the S30 further includes:
and S306, if the relationship curve is not matched with the factory design relationship curve, adjusting the lifting stroke of the high-speed gate valve rod according to the difference between the drawn relationship curve and the factory design relationship curve.
The invention provides a method for carrying out fault early warning on sudden load change of a turbine set based on pressure monitoring behind a high-speed regulating valve, aiming at solving the problem that the peak regulation performance of the turbine set is influenced by sudden load change caused by hardware fault of the high-speed regulating valve of the conventional turbine set, thereby realizing real-time evaluation of the frequency modulation capability of the high-speed regulating valve of the turbine and improving the peak regulation performance of the turbine set.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
FIG. 1 is a schematic flow diagram of the process of the present invention;
FIG. 2 is a high throttle flow characteristic curve;
FIG. 3 is a nozzle layout of the unit in the embodiment;
FIG. 4 is a schematic diagram of a load break failure mechanism;
fig. 5 is a time domain diagram of a first load runaway fault indicating power change of a load runaway occurring in a switching process of the unit GV2 in the embodiment;
fig. 6 is a time domain diagram of a second load runaway fault representing power change of a load runaway occurring in a switching process of the unit GV2 in the embodiment;
FIG. 7 is a characteristic curve of a high transfer gate with a unit failure;
FIG. 8 is a time domain plot of post-valve pressure at 25% no flow failure of a unit damper in an embodiment;
FIG. 9 is a time domain plot of post-valve pressure at 15% no flow failure of the set damper in an embodiment;
FIG. 10(1) is a lift axis view of the actual high governor connection section in an embodiment-there is a wear failure;
FIG. 10(2) is a large nut diagram of the connecting part of the actual high-speed adjusting door in the embodiment;
fig. 10(3) is a diagram illustrating an actual high-speed gate connecting portion of an embodiment of the present invention, and the implementation, functional features and advantages of the object of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
As shown in fig. 1 to 10, the method for evaluating the frequency modulation capability of the high-speed governor of the steam turbine for improving the peak shaving of the unit, provided by the invention, comprises the following steps:
s10, collecting DCS data of pressure after the valve of each high-pressure regulating valve of the unit from 0 to full opening when the unit is in a normal load operation state;
s20, setting the normal operation of the unit, and calculating the steam flow of each high-pressure regulating valve at different valve opening degrees;
s30, drawing a relation curve of the valve opening and the steam flow according to the valve opening of each high-pressure regulating valve of the unit and the calculated steam flow of each high-pressure regulating valve at different valve openings, wherein the drawn relation curve is matched with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, the next step is carried out;
s40 obtaining absolute difference values by subtracting data of any two adjacent moments in collected DCS data of pressure behind the valve, and selecting the maximum absolute difference value from the obtained absolute difference values to define the maximum absolute difference value as delta P'maxOf selected Δ P'maxMultiplying by a factor K, K>1, obtaining the maximum value DeltaPmax,I.e. by
ΔPmax＝KΔP’max(MPa), the minimum value of the absolute value of the pressure difference value after the valve between adjacent moments is 0, and the value range of the absolute value of the pressure difference value after the valve is obtained is [0, delta P ]max]Namely;
|ΔP|＝|Pn+1-Pn| (MPa)；
s50, if the pressure data after the valve collected by the unit at a certain time Tn is Pn, and the pressure data after the valve collected at the next time Tn +1 is Pn +1, the absolute value of the pressure variation in the period is:
|ΔP|＝|Pn+1-Pn|(MPa) (2)，
whether the value of | Δ P | is within the interval [0, Δ Pmax ] is judged, and when the value of | Δ P | exceeds the interval, it is judged that the hardware fault exists in the high-speed regulation gate.
Preferably, the S30 includes:
s301, under the condition that the unit is in a load operation state, switching the operation mode from a sequence valve to a single valve according to the operation regulation of the unit, and increasing the load of the unit to 95% on the basis;
s302, removing the coordination control and the automatic sliding pressure operation control of the unit, reducing the main steam pressure of the unit and increasing the comprehensive valve position instruction of the unit on the basis of keeping the load of the unit basically unchanged, so that the high regulating valve of the unit is in a fully open state, and determining the high regulating valve as a software fault reason or a hardware fault reason according to whether the load mutation phenomenon occurs in the process;
s303, respectively carrying out two-valve full-opening and three-valve full-opening tests of at least two groups by taking diagonal steam admission as a two-valve steam admission mode, and verifying the fault reason determined in S202 according to whether a load sudden change phenomenon occurs in the process;
s304, collecting data for configuration and continuous recording in the DCS, wherein the collection time interval is within 1S, calculating the flow characteristic of the high-speed regulating valve by using the collected related data through a Friedel formula, obtaining the hardware fault characteristics, and judging the hardware fault and the severity of the valve, wherein the Friedel formula is as follows;
wherein G is rated flow; g' is the variable working condition flow; p is a radical of1Is the rated main steam pressure; p is a radical of2To regulate post-stage pressure; p is a radical of1The main steam pressure under variable working conditions; p is a radical of2' is the pressure after the regulating stage when the working condition is changed; t is t1Is the rated main steam temperature; t is t1The main steam temperature is under variable working conditions;
s305, drawing a relation curve of the actual flow of the high-speed regulating valve and the opening degree of the valve according to the calculated actual flow, matching the drawn relation curve with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, entering the next step.
Preferably, the S30 further includes:
and S306, if the relationship curve is not matched with the factory design relationship curve, adjusting the lifting stroke of the high-speed gate valve rod according to the difference between the drawn relationship curve and the factory design relationship curve.
The steam turbine sequence valve load sudden change fault diagnosis method based on the high throttle switch test is implemented as follows:
firstly, the method comprises the following steps: and collecting DCS data of pressure behind the valve when the opening of each high-speed gate valve of the unit is from 0 to full opening under the normal load operation state of the unit. The traditional unit does not have a pressure measuring point behind the high-pressure regulating valve, so that the pressure behind the high-pressure regulating valve is obtained in a mode of increasing the pressure measuring point;
II, secondly: according to the normal operation setting of the unit, effective data are collected to calculate data such as steam flow of each high-pressure regulating valve in different valve opening degrees, a relation curve of the valve opening degrees and the steam flow is drawn, and whether an actually drawn curve is consistent with a designed curve or not is checked. If the two-step lifting stroke of the high-speed gate valve rod are consistent, the three steps are carried out, and if the two-step lifting stroke of the high-speed gate valve rod are inconsistent, further design modification needs to be carried out on the lifting stroke of the high-speed gate valve rod according to actual requirements; the specific operation steps are as follows:
(1): under the condition that the unit is in a load operation state, switching the operation mode from the sequence valve to the single valve according to the operation regulation of the unit, and increasing the load of the unit to about 95 percent on the basis;
(2): the coordination control and the automatic sliding pressure operation control of the unit are removed, and on the basis of keeping the load of the unit basically unchanged, the main steam pressure of the unit is manually reduced and the comprehensive valve position instruction of the unit is increased, so that the 4 high-regulating valves of the unit are in a fully-opened state; whether the fault reason is in the aspects of software or hardware can be determined by judging whether the load mutation phenomenon occurs in the test process;
(3): on the basis of the above test, the control mode of 4 high-speed regulating valves is changed into manual regulation, so that the opening degree of each high-speed regulating valve can be manually and independently regulated; then, at least two groups of two-valve full-opening and three-valve full-opening tests are respectively carried out in a mode that diagonal steam inlet is two-valve steam inlet; the determination of two pairs of fault reasons in the step two can be further verified through whether the load mutation phenomenon occurs in the test process;
(4): calculating the flow characteristic of the high-speed regulating valve by using the test data according to a Friedel formula, further extracting to obtain fault characteristics, judging the hardware fault and the severity of the valve,
in addition, in order to carry out accurate analysis, the test process data which is subjected to configuration and continuous recording in the DCS is collected after the test is finished, and the collection time interval is within 1 s; correlation calculations and analysis are then performed. The data acquisition parameters comprise high regulating opening (GV 1-GV 4), power, a total valve position instruction, steam pressure and steam temperature (main steam, regulating-stage rear steam and high exhaust steam), No. 1-No. 3 tile temperature and shaft vibration, EH oil pressure and back pressure. In addition, the relationship between the pressure of the stage group and the flow of the stage group under the variable working condition is reflected by a Foucaire formula, namely the actual flow (%); therefore, the flow relation calculation is carried out on the parameters of the opening process of the high-speed governor by selecting the flow calculation principle and the formula of the steam turbine. The basic form of its formula is:
wherein G is rated flow; g' is the variable working condition flow; p is a radical of1Is rated main steam pressure；p2To regulate post-stage pressure; p is a radical of1The main steam pressure under variable working conditions; p is a radical of2' is the pressure after the regulating stage when the working condition is changed; t is t1Is the rated main steam temperature; t is t1' is the main steam temperature under variable working conditions.
(5): drawing a relation curve of the actual flow of the high-speed regulating valve and the opening degree of the valve according to the calculated actual flow, checking whether a deviation exists between the curve and a design curve, and if the deviation exists, judging that the high-speed regulating valve has a fault and needing to be overhauled again, wherein the condition is shown in figure 6;
thirdly, the method comprises the following steps: as described above, the pressure change value between adjacent times is the largest within the opening degree change range represented by curve 2 in fig. 1. And D, processing the pressure data behind the high-pressure regulating valve collected in the step I, and subtracting the data at any two adjacent moments to obtain a difference value. Selecting the maximum value and taking absolute value to obtain delta P'max. In order to avoid excessive pre-alarm errors caused by too small a selected value, the maximum value is selected with a certain margin and multiplied by a coefficient K (K)>1) And obtaining the maximum value:
ΔPmax＝KΔP’max(MPa)
the minimum value which can be obtained by the absolute value of the pressure difference value after the valve between the adjacent time instants is 0. Thereby obtaining valve back pressure
The value range of the absolute value of the force difference is [0, delta Pmax]；|ΔP|＝|Pn+1-Pn|(MPa)
Fourthly, the method comprises the following steps: set the unit at a certain time TnAcquired post-valve pressure data is PnAt the next time Tn+1Time-acquired post-valve pressure data is Pn+1The absolute value of the pressure change amount during this period is:
fifthly: whether the value of | Δ P | is within the interval [0, Δ Pmax ] is judged, and when the value of | Δ P | exceeds the interval, it can be judged that the hardware fault exists in the high-speed gate.
The unit of the actual operation case is a 200MW heat supply unit, and the phenomenon of load sudden change occurs when the unit operates.
FIG. 2 is a high-throttle flow characteristic curve, in which when the valve is just opened, the steam flow passing through the valve is small, the steam flow increases with the increase of the opening of the valve, but when the opening of the valve is close to the maximum opening, the steam flow and the opening of the valve show nonlinear characteristics; FIG. 3 is a nozzle layout of the unit in the embodiment; fig. 4 is a schematic diagram of a load sudden change failure mechanism, in which a connection portion between a valve head and a valve rod is worn, the valve head is loosened, a balance exists between valve head gravity and steam flow force, when the valve opening is small, the steam generated by steam is not enough to overcome the valve head gravity, and even if the valve opening is increased, no steam flows through the valve until the steam flow force is large enough to overcome the valve head gravity, the valve is suddenly opened, so that the steam flow has a sudden change phenomenon, and further a load sudden change is generated; fig. 5 and 6 are time domain diagrams of power changes when a unit generates a load sudden change phenomenon. The test results show that all 4 high-speed gates have different degrees of clearance faults, wherein the fault of GV2 is the most serious, and two obvious faults occur.
Fig. 7 is a characteristic curve of a high-speed governor with a unit fault, which can be seen by a calculation method introduced in step two: when the GV2 is at 30% opening, the opening is increased, but the flow is decreased first and then increased, and the change of the flow fluctuation value accounts for about 13% of the flow of the whole throttle; at 43% opening, the load suddenly changes (accounting for about 10% of the whole throttle flow);
fig. 8 and 9 are time domain graphs of the pressure after the valve when the unit high-pressure regulating valve GV2 has a fault, and the two pressure after the valve measuring point change graphs correspond to the two graphs in fig. 5 and 6, respectively. Because the relative amount of change in the post-valve pressure is relatively large; in addition, the pressure behind the valve is used as a detection variable in daily operation and can be used for evaluating the frequency modulation capability of the unit regulating valve in real time; especially when the unit governing valve has small clearance and has less than 2MW to load influence, the governing valve with the fault point and the fault severity can be judged by observing the pressure behind the valve. In practice, if the gate regulating action is slow, the load sudden change is smaller; although this also affects the frequency modulation capability of the unit, it is difficult for the operator to find the problem. In contrast, the presence of these two load transients is readily apparent using the method of increasing the post-valve pressure measurement point set forth herein.
Fig. 10(1) - (3) are respectively a lifting shaft diagram, a large nut diagram and a connecting sleeve diagram of a connecting part of a fault high-speed adjusting door of the unit, and the whole device of the fault high-speed adjusting door is overhauled by stopping the machine, so that the result proves that gaps exist among the large nut, the lifting shaft and the middle connecting sleeve part due to abrasion, and the load of the unit is suddenly reduced.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and all modifications and equivalents of the present invention, which are made by the contents of the present specification and the accompanying drawings, or directly/indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (2)
1. A method for evaluating the frequency modulation capability of a high-speed governing valve of a steam turbine for improving the peak modulation of a unit is characterized by comprising the following steps of:
s10, collecting DCS data of pressure after the valve of each high-pressure regulating valve of the unit from 0 to full opening when the unit is in a normal load operation state;
s20, setting the normal operation of the unit, and calculating the steam flow of each high-pressure regulating valve at different valve opening degrees;
s30, drawing a relation curve of the valve opening and the steam flow according to the valve opening of each high-pressure regulating valve of the unit and the calculated steam flow of each high-pressure regulating valve at different valve openings, wherein the drawn relation curve is matched with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, the next step is carried out;
s40 obtaining absolute difference values by subtracting data of any two adjacent moments in collected DCS data of pressure behind the valve, and selecting the maximum absolute difference value from the obtained absolute difference values to define the maximum absolute difference value as delta P'maxOf selected Δ P'maxMultiplying by a factor K, K>1, obtaining the maximum value DeltaPmaxI.e. by
ΔPmax＝KΔP’max(MPa), the minimum value of the absolute value of the pressure difference value after the valve between adjacent moments is 0, and the value range of the absolute value of the pressure difference value after the valve is obtained is [0, delta P ]max]I.e. by
|ΔP|＝|Pn+1-Pn|(MPa)；
S50, if the pressure data after the valve collected by the unit at a certain time Tn is Pn, and the pressure data after the valve collected at the next time Tn +1 is Pn +1, the absolute value of the pressure variation in the period is:
|ΔP|＝|Pn+1-Pn|(MPa)
judging whether the value of | delta P | is in the interval [0, delta Pmax]When the value of the | delta P | exceeds the interval, judging that a hardware fault exists in the high-speed gate;
the S30 includes:
s301, under the condition that the unit is in a load operation state, switching the operation mode from a sequence valve to a single valve according to the operation regulation of the unit, and increasing the load of the unit to 95% on the basis;
s302, removing the coordination control and the automatic sliding pressure operation control of the unit, reducing the main steam pressure of the unit and increasing the comprehensive valve position instruction of the unit on the basis of keeping the load of the unit basically unchanged, so that the high regulating valve of the unit is in a fully open state, and determining the high regulating valve as a software fault reason or a hardware fault reason according to whether the load mutation phenomenon occurs in the process;
s303, respectively carrying out two-valve full-opening and three-valve full-opening tests of at least two groups by taking diagonal steam admission as a two-valve steam admission mode, and verifying the fault reason determined in S302 according to whether a load sudden change phenomenon occurs in the process;
s304, collecting data for configuration and continuous recording in the DCS, wherein the collection time interval is within 1S, calculating the flow characteristic of the high-speed regulating valve by using the collected related data through a Friedel formula, acquiring the hardware fault characteristics, and judging the hardware fault and the severity of the valve, wherein the Friedel formula is as follows:
wherein G is rated flow; g' is the variable working condition flow; p is a radical of1Is the rated main steam pressure; p is a radical of2To regulate post-stage pressure; p is a radical of1The main steam pressure under variable working conditions; p is a radical of2' is the pressure after the regulating stage when the working condition is changed; t is t1Is the rated main steam temperature; t is t1The main steam temperature is under variable working conditions;
s305, drawing a relation curve of the actual flow of the high-speed regulating valve and the opening degree of the valve according to the calculated actual flow, matching the drawn relation curve with a factory design relation curve, and if the drawn relation curve is matched with the factory design relation curve, entering the next step.
2. The method for evaluating the fm capability of a steam turbine high-speed governor for improving peak shaving of a unit according to claim 1, wherein said S30 further comprises:
and S306, if the relationship curve is not matched with the factory design relationship curve, adjusting the lifting stroke of the high-speed gate valve rod according to the difference between the drawn relationship curve and the factory design relationship curve.
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| CN112282867B (en) * | 2020-10-15 | 2023-06-27 | 华能重庆珞璜发电有限责任公司 | Method for solving problem of vibration of EH oil pipeline caused by primary frequency modulation of steam turbine |
| CN113586175A (en) * | 2021-07-07 | 2021-11-02 | 哈电发电设备国家工程研究中心有限公司 | Detection method for flow characteristic deviation fault of high transfer valve |
| CN113446073B (en) * | 2021-08-11 | 2023-03-24 | 内蒙古京隆发电有限责任公司 | Fault diagnosis method for high-pressure adjusting valve of steam turbine |
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