Reciprocating compressor phase identification method and program product

Abstract

The invention relates to the technical field of online monitoring and diagnosis of oil and gas field reciprocating compressors, in particular to a reciprocating compressor phase identification method and a program product, and the method comprises the steps: dividing dynamic pressure data into a plurality of data groups according to a time sequence, and screening out a plurality of data groups for analysis; the working process of the data set is determined, two continuous expansion starting points are determined, and the whole period of the dynamic pressure data is obtained; based on the initial structure design of the reciprocating compressor, the initial expansion angle difference between the inner side and the outer side of the cylinder and the expansion angle difference between all stages of cylinders are obtained through calculation in combination with dynamic pressure data; whether the dynamic pressure data are normal or not is judged through the expansion angle difference, so that whether phase recognition can be carried out or not is judged, and the accuracy of phase recognition is greatly improved by combining the working mechanism of the reciprocating compressor and multi-cylinder data calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of online monitoring and diagnosis of reciprocating compressors in oil and gas fields, and particularly relates to a reciprocating compressor phase identification method and program product. BACKGROUND

[0002] A reciprocating compressor is a positive displacement compressor, which mainly functions to compress and transport gas, and realizes the compression and transportation of gas through the reciprocating movement of a piston in a cylinder, and is widely used in various industrial fields. The working principle is that when the piston moves downward, the volume in the cylinder increases, the inlet valve opens, and the exhaust valve closes, so that air is sucked into the cylinder to complete the intake process; when the piston moves upward, the volume in the cylinder decreases, the outlet valve opens, and the inlet valve closes to complete the compression process of the gas. This mechanical movement makes a certain volume of gas sequentially sucked into and discharged from the closed space, thereby increasing the static pressure of the gas.

[0003] The fault diagnosis of a reciprocating compressor is different from that of a rotating machine, and some typical faults have obvious mechanism characteristics in the angular domain. Therefore, the key phase signal is crucial for the fault diagnosis of the reciprocating compressor. Since the key phase signal can provide an angular coordinate system for various signals of the fault diagnosis system, whether or not the key phase signal exists or the accuracy of the key phase signal directly relates to whether the fault diagnosis conclusion is correct or not. In actual application, problems such as no key phase sensor, large installation error of the key phase sensor or sensor damage often occur, which often causes the reciprocating compressor to have no key phase signal or the key phase to be invalid, and further causes the fault diagnosis to be unable to be effectively implemented. SUMMARY

[0004] The technical problem to be solved by the present application is that the no key phase sensor, large installation error of the key phase sensor or sensor damage causes the phase detection of the reciprocating compressor to be inaccurate, and the purpose is to provide a reciprocating compressor phase identification method and program product, which realizes the phase identification and calibration under the condition of no key phase sensor, large installation error of the key phase sensor or sensor damage, and is convenient for subsequent fault diagnosis.

[0005] The present application is realized by the following technical scheme:

[0006] A reciprocating compressor phase identification method, comprising:

[0007] Obtaining dynamic pressure data of multiple cylinders without key phase;

[0008] Dividing the dynamic pressure data into multiple data groups in time sequence, and screening multiple data groups for analysis;

[0009] Determining the working process in which the data group is located, and determining two continuous expansion starting points to obtain an integral period of the dynamic pressure data;

[0010] Based on the initial structure design of the reciprocating compressor, the initial angle difference of expansion inside and outside the cylinder and the expansion angle difference between cylinders are obtained by combining dynamic pressure data calculation;

[0011] If the angle difference is within the set range, it indicates that the dynamic pressure data is normal, and the phase is identified as normal; if any angle difference is not within the set range, it indicates that the dynamic pressure data is abnormal, and the phase is identified as abnormal.

[0012] Specifically, the method for obtaining dynamic pressure data comprises:

[0013] Determine the speed fluctuation range N1-N2 of the reciprocating compressor;

[0014] According to the speed fluctuation range, obtain the longest working cycle

[0015] Set the sampling time interval Δt, and intercept the continuous dynamic pressure data inside and outside each cylinder with a time length of xT max , x is a constant set;

[0016] Obtain dynamic pressure data A={D 11O , D 11N ,..., D ijO , D ijN}, wherein D is a data group continuously intercepted in time sequence, i is the number of stages, i=1, 2, 3…, j is the same number of different cylinder order, j=1, 2, 3…, O is the outside of the cylinder, and N is the inside of the cylinder.

[0017] Specifically, the method for screening multiple sets of analysis data from the outside dynamic pressure data comprises:

[0018] Obtain the maximum value max(D ijO ) and the minimum value min(D ijO ) in the outside dynamic pressure data, wherein D ijO ={p1, p2,..., p n} is the outside dynamic pressure data of the jth cylinder of the ith stage, and p n is the nth outside data of the jth cylinder of the ith stage;

[0019] Determine the median value of the outside pressure

[0020] Determine the neighborhood D ijO-mid ={(p o )|p o =(0.95-1.05)p midO} of the median value of the outside pressure, o is the data sequence number, and all data points in the neighborhood are traversed, if the data sequence numbers of two data points differ by 1, they are classified into the same data group, and multiple data groups are obtained;

[0021] Sort multiple data sets by time series and select the middle M data sets consecutively.

[0022] Specifically, the dynamic pressure data includes both expansion and compression processes. For data points within the same data set, a judgment is made if p... o -p o-s ≤0&p o -p o+s If ≥0, then this data set is determined to be an expansion process; otherwise, this data set is a compression process. s = 1, 2, 3... are random numbers.

[0023] Specifically, methods for filtering multiple sets of analytical data using internal dynamic pressure data include:

[0024] Obtain the maximum value (max(D)) from the internal dynamic pressure data. ijN ) and minimum value min(D ijN ), where D ijN ={p1, p2, ..., p m} represents the dynamic pressure data of the inner side of the j-th cylinder in the i-th stage, p m This refers to the m-th outermost data of the j-th cylinder in the i-th stage;

[0025] Determine the median internal pressure

[0026] Determine the neighborhood D of the median internal pressure. ijN-mid ={(p n )|p n =(0.95~1.05)p midN}, where n is the data index, and all data points in the neighborhood are traversed. If the data indices of two data points differ by 1, they are grouped into the same data group, resulting in multiple data groups.

[0027] Sort multiple data sets by time series and select the middle M data sets consecutively.

[0028] Optionally, the dynamic pressure data includes both expansion and compression processes. For data points within the same data set, a judgment is made if p... n -p n-s ≤0&p n -p n+s If ≥0, then this data set is determined to be an expansion process; otherwise, this data set is a compression process. s = 1, 2, 3... are random numbers.

[0029] Specifically, methods for obtaining whole-cycle dynamic pressure data include:

[0030] Filter the data set D from M data sets that is in the expansion process. d ;

[0031] Choose any D d A data point p k Starting from k, numbers are continuously taken backwards until the previous data group D, which is in the compression process, is reached. d-1 ;

[0032] Calculate the slope of adjacent data points

[0033] Calculate the dynamic pressure data p for data with serial number kr. k-r Percentage difference from maximum dynamic pressure data Where, p max For maximum pressure data, p′ max This refers to the actual pressure in the exhaust pipe.

[0034] If conditions one, two, and three are all satisfied simultaneously, then p is determined. k-r This is the starting point of the expansion;

[0035] Condition 1: K r The slope of the last u1 data sets is negative, and the change range does not exceed υ1%.

[0036] Condition 2: K r The slope of the first u2 data sets is either negative or positive, and the range of change exceeds υ2%.

[0037] Condition 3: Δp r Not greater than 3%;

[0038] Repeat the above steps to obtain data set D. d+2 The expansion starting point p l-r And obtain the integer period T=(lk)Δt of dynamic pressure data.

[0039] Specifically, the initial structural design of the reciprocating compressor is as follows: the outer dead point of the first-stage cylinder is 0 degrees, the outer dead point of the second-stage cylinder in the same cycle is 0+η1 degrees, the outer dead point of the third-stage cylinder in the same cycle is 0+η2 degrees, and so on, designed according to equal angles, and the phase difference between the inner dynamic pressure data and the outer dynamic pressure data of the cylinder in the same cycle is 180 degrees.

[0040] Obtain data set D for each stage of the cylinder d and data group D d+2 Corresponding inner expansion initiation point and outer expansion initiation point Where a, b, c, d, e, f, a1, b1, c1, and d1 are all data sequence numbers;

[0041] Calculate the initial expansion angle difference between the inside and outside of the cylinder. Where Δm is the angle difference between two expansion points on the inner side of the m-stage cylinder, and Δ′m is the angle difference between two expansion points on the outer side of the m-stage cylinder;

[0042] Calculate the difference in initial expansion angles between the two stages of cylinders.

[0043] Optionally, the setting range for the initial expansion angle difference between the inner and outer sides of the cylinder is:

[0044]

[0045] The setting range for the difference between the two initial expansion angles of each cylinder is as follows:

[0046] A reciprocating compressor phase identification terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a reciprocating compressor phase identification method as described above.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] This invention acquires multiple dynamic pressure data points and obtains the corresponding expansion start point and whole cycle based on the dynamic pressure data. Then, it calculates the corresponding expansion angle difference and uses the expansion angle difference to determine whether the dynamic pressure data is normal, thereby determining whether phase identification can be performed. It can realize phase identification and calibration in cases where there is no key phase sensor, the key phase sensor has a large installation error, or the sensor is damaged, which facilitates subsequent fault diagnosis. Moreover, it does not require complex unit, valve, and other structural parameters, mathematical models, etc. By combining the working mechanism of reciprocating compressors and multi-cylinder data calibration, the accuracy of phase identification is greatly improved. Attached Figure Description

[0049] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0050] Figure 1 This is a schematic flowchart of a reciprocating compressor phase identification method according to the present invention.

[0051] Figure 2 This refers to the first-level external dynamic pressure data as described in this invention.

[0052] Figure 3 This is the first-level internal dynamic pressure data according to the present invention.

[0053] Figure 4 This refers to the secondary lateral dynamic pressure data as described in this invention.

[0054] Figure 5 It is the secondary inner dynamic pressure data according to the present invention.

[0055] Figure 6 It is the first-order outer slope curve (data serial number 1046-1580) according to the present invention.

[0056] Figure 7 It is the first-order outer slope curve (data serial number 2545-3090) according to the present invention.

[0057] Figure 8 It is the slope curve of the first-order inner side (data serial number 343-850) according to the present invention.

[0058] Figure 9 It is the slope curve of the first-order inner side (data serial number 1858~2350) according to the present invention.

[0059] Figure 10 It is the second-order outer slope curve (data number 200-780) according to the present invention.

[0060] Figure 11 It is the second-order outer slope curve (data serial number 1719-2300) according to the present invention.

[0061] Figure 12 It is the slope curve of the second-order inner side (data serial number 956-1540) according to the present invention.

[0062] Figure 13 It is the slope curve of the second-order inner side (data serial number 2475~3040) according to the present invention.

[0063] Figure 14 It is the percentage difference curve of the first-level outer side (data serial numbers 1046-1580) according to the present invention.

[0064] Figure 15 It is the percentage difference curve of the first-level outer side (data serial numbers 2545-3090) according to the present invention.

[0065] Figure 16 It is the percentage curve of the difference between the first-level inner side (data serial numbers 343-850) according to the present invention.

[0066] Figure 17 It is the percentage curve of the difference between the first-level inner side (data serial numbers 1858-2350) according to the present invention.

[0067] Figure 18 It is the percentage curve of the difference between the secondary outer sides (data numbers 200-780) according to the present invention.

[0068] Figure 19 It is the percentage curve of the difference between the secondary outer sides (data numbers 1719-2300) according to the present invention.

[0069] Figure 20 It is the percentage curve of the difference between the secondary inner sides (data numbers 956-1540) according to the present invention.

[0070] Figure 21 It is the percentage curve of the difference between the second-order inner sides (data numbers 2475-3040) according to the present invention. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0072] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0073] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0074] Example 1

[0075] like Figure 1 As shown, a phase identification method for a reciprocating compressor includes:

[0076] The system acquires dynamic pressure data from a multi-cylinder reciprocating compressor without a key phase. "Keyless" means that phase identification is performed solely through pressure data without using traditional physical phase signals. This data is a time-series of the pressure inside and outside each cylinder, capturing the dynamic changes of each cylinder under different operating conditions. This is because the working cycle of a reciprocating compressor includes intake, compression, expansion, and exhaust processes; by recording the pressure changes inside and outside the cylinder, the working state of the piston at different positions can be indirectly reflected.

[0077] The dynamic pressure data was divided into multiple data groups according to time sequence, and multiple data groups were selected for analysis.

[0078] The system determines the operating process of each data set and identifies two consecutive expansion start points to obtain the entire cycle of dynamic pressure data. It judges the operating process (e.g., expansion or compression) corresponding to each data set, and then determines a complete operating cycle based on the start point of the expansion process. The entire cycle is the time it takes for the compressor to move from one expansion start point to the next. By identifying the expansion start point, the compressor's operating cycle can be accurately captured. The expansion start point is typically the location where the pressure begins to drop, marking the start of gas expansion in the cylinder. Two consecutive expansion start points constitute a complete pressure cycle.

[0079] Based on the initial structural design of the reciprocating compressor, the initial expansion angle difference between the inner and outer sides of the cylinder and the expansion angle difference between each stage of the cylinder are calculated using dynamic pressure data. This step combines the initial structural design parameters of the reciprocating compressor (such as cylinder arrangement and angles) with the actual measured dynamic pressure data to calculate the initial expansion angle difference between the inner and outer sides of each cylinder, as well as the expansion angle difference between each stage of the cylinder. According to the compressor's structural design, there is usually a certain phase difference between different cylinders. By calculating these phase differences, it can be verified whether the compressor is operating normally according to the design. The expansion angle difference between the inner and outer sides of the cylinder reflects the expansion synchronicity of each cylinder, while the expansion angle difference between each stage of the cylinder reflects the working coordination of different stages of the cylinder.

[0080] If all angle differences are within the set range, the dynamic pressure data is normal, and the phase is identified as normal. If any angle difference is outside the set range, the dynamic pressure data is abnormal, and the phase is identified as abnormal. Phase issues in reciprocating compressors directly affect cylinder efficiency and safety. Analyzing angle differences can identify potential abnormal operating conditions, thus providing a basis for fault diagnosis and maintenance.

[0081] Example 2

[0082] This embodiment provides a specific implementation based on Embodiment 1.

[0083] The first step is to obtain dynamic pressure data for the multi-cylinder bondless phase.

[0084] Considering the fluctuation in the actual speed of the reciprocating compressor, assuming the speed fluctuation range is N1 to N2, the longest working cycle is obtained based on the speed fluctuation range. Set a sampling time interval Δt (all data are collected at equal intervals), and set a time length of xT. max Continuous dynamic pressure data is extracted from the inner and outer sides of each cylinder body, where x is a set constant, and x = 3 can be selected; the dynamic pressure data A = {D} is obtained. 11O D 11N , ..., D ijO D ijN}, where D is a data set continuously extracted according to the time sequence, i is the level, i = 1, 2, 3..., j is the sorting of different cylinders in the same level, j = 1, 2, 3..., O is the outer side of the cylinder body, and N is the inner side of the cylinder body.

[0085] The second step is to divide the dynamic pressure data into multiple data groups according to time sequence, and then select multiple data groups for analysis.

[0086] Taking the external dynamic pressure data as an example for analysis, let's assume D ijO ={p1, p2, ..., p n}, where n is the total number of data points in the dynamic pressure data, and the maximum value (max(D)) among the outer dynamic pressure data points is calculated. ijO ) and minimum value min(D ijO ), where D ijO ={p1, p2, ..., p n} represents the dynamic pressure data on the outer side of the j-th cylinder in the i-th stage, p n This refers to the nth outermost data of the jth cylinder in the i-th stage.

[0087] Determine the median of the lateral pressure using the maximum and minimum values. As can be seen from the working process of the reciprocating compressor, the maximum value of the dynamic pressure data will appear during the exhaust process, and the minimum value of the dynamic pressure data will appear during the intake process. The expansion and compression processes are between the intake and exhaust processes, so the median pressure will appear during the expansion or compression process.

[0088] Determine the neighborhood D of the median external pressure ijO-mid ={(p o )|p o =(0.95~1.05)p midO}, where o is the data sequence number.

[0089] Since the interception time length is xT max Therefore, points near the median will be scattered in different regions (i.e., belong to different working stages). Thus, all data points in the neighborhood are traversed. If the data indexes of two data points differ by 1, they are grouped into the same data group (i.e., belong to the same compression process or the same expansion process), and finally multiple data groups are obtained.

[0090] Distinguish D ijO-mid The data points in the data are located during the expansion or compression process of the reciprocating compressor. As can be seen from the working process of the reciprocating compressor, the data points during the expansion process gradually decrease in value as the sequence number increases, and the slope of the expansion curve is negative. Conversely, the slope of the compression curve is positive. Therefore, when p... o -p o-s ≤0&p o -po+s ≥0, where s=1,2,3… are random numbers. If the condition is satisfied, the system is in the expansion phase; otherwise, it is in the compression phase.

[0091] Considering the randomness of data extraction, where the start or end point of the data falls within a certain working process and is not a complete cycle, which is detrimental to subsequent data processing, multiple data groups are sorted according to time series, and the middle M data groups are selected consecutively. In this embodiment, four data groups are selected and labeled as D. d D d+1 D d+2 D d+3 .

[0092] The third step is to determine the working process of the data set and identify two consecutive expansion start points to obtain the whole cycle of dynamic pressure data.

[0093] Based on the four sets of data in step two, select one set of data that is in the process of expansion, let's say it's D. d ; Choose any D d A data point p k Starting from k, numbers are continuously taken backwards until the previous data group D, which is in the compression process, is reached. d-1 ; Calculate the slope of adjacent data points

[0094] Simultaneously calculate the dynamic pressure data p for data with index kr. k-r Percentage difference from maximum dynamic pressure data Where, p max For maximum pressure data, p′ max This refers to the actual pressure in the exhaust pipe.

[0095] If conditions one, two, and three are all satisfied simultaneously, then p is determined. k-r This is the starting point of the expansion;

[0096] Condition 1: K r The slope of the last u1 data sets is negative, and the change range does not exceed υ1%.

[0097] Condition 2: K r The slope of the first u2 data sets is either negative or positive, and the range of change exceeds υ2%.

[0098] Condition 3: Δp r Not greater than 3%;

[0099] Repeat the above steps to obtain data set D. d+2 The expansion starting point p l-r And obtain the integer period T=(lk)Δt of dynamic pressure data.

[0100] The fourth step involves calculating the initial expansion angle difference between the inside and outside of the cylinder and the expansion angle difference between each stage of the cylinder, based on the initial structural design of the reciprocating compressor and combined with dynamic pressure data.

[0101] If all angle differences are within the set range, the dynamic pressure data is normal, and the phase is identified as normal; if any angle difference is outside the set range, the dynamic pressure data is abnormal, and the phase is identified as abnormal.

[0102] The piston movement positions of each cylinder in a reciprocating compressor are not necessarily synchronized, that is, they will not be at the outer dead center or inner dead center at the same time. Instead, there is a certain angle difference. The angle difference value has been determined during the structural design. Assuming that the first-stage cylinder is taken as the reference, the outer dead center of the first-stage cylinder is 0 degrees, the outer dead center of the second-stage cylinder in the same cycle is 0+η1 degrees, the outer dead center of the third-stage cylinder in the same cycle is 0+η2 degrees, and so on, it is designed according to equal angle division. The phase difference between the inner dynamic pressure data and the outer dynamic pressure data of the cylinder in the same cycle is 180 degrees.

[0103] Repeat steps two and three to determine the expansion start points on the inner and outer sides of each cylinder (selecting the two middle ones), thus obtaining the data set D for each cylinder. d and data group D d+2 Corresponding inner expansion initiation point and outer expansion initiation point Where a, b, c, d, e, f, a1, b1, c1, and d1 are all data sequence numbers.

[0104] Calculate and verify the initial expansion angle difference between the inner and outer sides and between each cylinder stage during the same period.

[0105] Calculate the initial expansion angle difference between the inside and outside of the cylinder. Where Δm is the angle difference between two expansion points on the inner side of the m-stage cylinder, and Δ′m is the angle difference between two expansion points on the outer side of the m-stage cylinder;

[0106] Calculate the difference in initial expansion angles between the two stages of cylinders.

[0107] Where a-a1 is the difference in expansion angle between the outer side of level 1 and the outer side of level m; c-c1 is the difference in expansion angle between the inner side of level 1 and the inner side of level m; the angle difference between level 1 and the other levels has already been calculated in the formula, so the angle difference between each level has been calculated, and there is no need to calculate the angle difference between level 2 and other levels.

[0108] The angle difference was verified, and the set range for the initial angle difference between the inner and outer sides of the cylinder expansion was:

[0109]

[0110] The setting range for the difference between the two initial expansion angles of each cylinder is as follows:

[0111]

[0112] If a set of data does not meet the above difference, it indicates that there is a problem with the dynamic pressure data and it cannot be used for phase correction.

[0113] Example 3

[0114] This embodiment replaces the second step of Embodiment 2, and the method for filtering multiple sets of analytical data using internal dynamic pressure data includes:

[0115] Obtain the maximum value (max(D)) from the internal dynamic pressure data. ijN ) and minimum value min(D ijN ), where D ijN ={p1, p2, ..., p m} represents the dynamic pressure data of the inner side of the j-th cylinder in the i-th stage, p m This refers to the m-th outermost data of the j-th cylinder in the i-th stage;

[0116] Determine the median internal pressure

[0117] Determine the neighborhood D of the median internal pressure. ijN-mid ={(p n )|p n =(0.95~1.05)p midN}, where n is the data index, and all data points in the neighborhood are traversed. If the data indices of two data points differ by 1, they are grouped into the same data group, resulting in multiple data groups.

[0118] Sort multiple data sets by time series and select the middle M data sets consecutively.

[0119] Optionally, the dynamic pressure data includes both expansion and compression processes. For data points within the same data set, a judgment is made if p... n -p n-s ≤0&p n -p n+s If ≥0, then this data set is determined to be an expansion process; otherwise, this data set is a compression process. s = 1, 2, 3... are random numbers.

[0120] Example 4

[0121] Reference Figures 1-21 This embodiment provides a specific example.

[0122] The first step is to obtain dynamic pressure data for the multi-cylinder bondless phase.

[0123] The actual reciprocating compressor speed fluctuation range is 990rpm~1000rpm, and the longest working cycle is Continuous dynamic pressure data for the inner and outer sides of each cylinder were extracted with a time duration of 0.1818 seconds (all data were collected at equal time intervals of 3.971 x 10⁻⁶). -5 s), in total: A = {D} 11O D 11N D 21O D 22N}, data such Figures 2-5 As shown.

[0124] The second step involves defining all expansion and compression processes in the dynamic pressure data, dividing and sorting the expansion and compression process data according to regions, and selecting the expansion regions that meet the requirements to prepare for the next step.

[0125] The dynamic pressure data were divided into multiple data groups according to time sequence, and multiple data groups were selected for analysis.

[0126] Since the dynamic pressure data characteristics of reciprocating compressors are related to the working process, dynamic pressure data in different regions can be filtered and differentiated by combining the working process. A reciprocating compressor has four working processes under normal operating conditions. For the outer cylinder: Expansion process: When the piston moves from outer dead center to inner dead center, the gas in the cylinder clearance expands, the cylinder volume increases, and the pressure in the outer cylinder decreases. Intake process: When the cylinder pressure drops below the gas pressure in the intake pipe, the pressure difference between the outer cylinder and the intake pipe overcomes the valve spring force, pushing open the intake valve plate, allowing gas to enter the cylinder. As the piston continues to move towards inner dead center, gas continues to be drawn into the cylinder until the piston reaches inner dead center, ending the intake process. Compression process: When the piston moves in the opposite direction towards outer dead center, the volume of the outer cylinder gradually decreases, and the gas begins to compress, causing the gas pressure to continuously increase. Exhaust process: When the cylinder pressure rises above the gas pressure in the exhaust pipe, the gas in the cylinder overcomes the exhaust valve spring force through the gas pressure difference and enters the exhaust pipe, continuously being discharged until the piston reaches outer dead center. Finally, the piston moves in the opposite direction again, repeating the above actions. In the same cylinder, the inner cylinder will lag behind the outer cylinder by 180° in each working process.

[0127] Based on external dynamic pressure data D 11O For example, to find the maximum value max(D) in the dynamic pressure data. 11O =2.0218 and the minimum value min(D) 11O = 0.5884.

[0128] Find the median using the maximum and minimum values:

[0129]

[0130] As can be seen from the working process of the reciprocating compressor, the maximum value of the dynamic pressure data will appear during the exhaust process, and the minimum value of the dynamic pressure data will appear during the intake process. The expansion and compression processes are between the intake and exhaust processes, so the median pressure will appear during the expansion or compression process.

[0131] Find the data points near the median, D ijO-mid ={(p o )|p o =(0.95~1.05)p midO If two adjacent data indices differ by 1, they are assigned to the same region; otherwise, they are assigned to the next region. The calculation is: D1 = {p} 56 ~p 82}, D2={p 1022 ~p 1046}, D3={p 1576 ~p 1599}, D4={p 2514 ~p 2544}, D5={p 3076 ~p 3102}, D6={p 4042 ~p 4066}

[0132] To distinguish whether data points D1 to D6 are in the expansion or compression process of the reciprocating compressor, based on the working process of the reciprocating compressor, the data points in the expansion process gradually decrease in value as the sequence number increases, and the slope of the expansion curve is negative. Conversely, the compression process shows the opposite, with a positive curve slope. This is determined through the following calculations: p o -p o-s ≤0&p o -p o+s ≥0, therefore D1={p 56 ~p 82}、D3={p 1576 ~p 1599}、D5={p 3076 ~p 3102} is in the process of expansion, D2={p 1022 ~p 1046}, D4={p 2514 ~p 2544}, D6={p 4042 ~p 4066 It is currently in the compression process.

[0133] Considering the randomness of data extraction, the starting or ending point of the data may fall within a certain working process, not a complete cycle, which is not conducive to subsequent data processing. Therefore, four consecutive sets of data in the middle are selected: D2 = {p 1022 ~p 1046}~D5={p3076 ~p 3102 We will proceed with the next step of the analysis.

[0134] The third step is to determine the working process of the data set and identify two consecutive expansion start points to obtain the whole cycle of dynamic pressure data.

[0135] Based on the four selected data sets, select one set that is in the process of dilation, select D3, and arbitrarily select a data point p in D3. 1580 Starting with serial number 1580,

[0136] Continuously take numbers forward and calculate the slope (take numbers forward up to the previous compressed region, i.e., 1046). The calculated slope is as follows: Slope curve as Figures 6-13 As shown.

[0137] Simultaneously calculate: The percentage difference curve is as follows Figures 14-21 As shown.

[0138] When the following conditions are met simultaneously:

[0139] Condition 1: K r The slope of the last 10 data sets is negative, and the variation does not exceed 10%.

[0140] Condition 2: K r The slope of the first 10 data sets is either negative or positive, and the range of change exceeds 30%;

[0141] Condition 3: Δp r No more than 15%.

[0142] Based on the above rules, the data sequence numbers that meet the conditions are 1508 to 1500. To reduce errors, the intermediate data is selected as the starting point for inflation, i.e., p. 1504 It is considered the starting point of expansion.

[0143] Calculate and judge the D5 data according to the content of step 3, and find the sequence number 3000; two consecutive expansion starting points form a dynamic pressure data cycle, and the cycle is: T=(3000-1504)×3.971×10 -5 =0.59s.

[0144] The fourth step is to use multi-cylinder dynamic pressure data to determine the accuracy of the data.

[0145] Based on the initial structural design of the reciprocating compressor, the initial expansion angle difference between the inside and outside of the cylinder and the expansion angle difference between each stage of the cylinder are calculated using dynamic pressure data.

[0146] If all angle differences are within the set range, the dynamic pressure data is normal, and the phase is identified as normal; if any angle difference is outside the set range, the dynamic pressure data is abnormal, and the phase is identified as abnormal.

[0147] Due to issues such as sensor malfunctions and abnormal data acquisition, some multi-cylinder, multi-stage dynamic pressure data may exhibit significant deviations, leading to erroneous analytical conclusions in energy efficiency monitoring and fault diagnosis. However, because there is a fixed phase relationship between the dynamic pressure data of multiple stages and cylinders, the accuracy of the data can be determined by comparing the dynamic pressure data of each cylinder.

[0148] The data in this embodiment comes from a two-stage four-cylinder symmetrical reciprocating compressor. The first-stage cylinder is used as the reference, with the outer dead center at 0 degrees. The outer dead center of the second-stage cylinder in the same cycle is 180 degrees.

[0149] The dynamic pressure data inside and outside a single cylinder in the same cycle are 180 degrees out of phase.

[0150] Repeat steps two and three to determine the expansion start points on the inner and outer sides of each cylinder stage (select the two middle ones), and mark them as: {(p 1O 1504 p 1O 3000) , (p 1N 749 p 1N 2247 ), (p 2O 747 p 2O 2250 ), (p 2N 1483 p 2N 2984 )}, calculate and verify the initial expansion angle difference between the inner and outer sides and between each cylinder in the same period.

[0151] Difference in angle between the inner and outer sides of each cylinder:

[0152]

[0153] Cylinder angle difference:

[0154]

[0155] The data all meet the above difference, indicating that there are no problems with the dynamic pressure data of each stage and cylinder, and it can be used for phase correction.

[0156] Example 5

[0157] A computer program product includes a computer program / instructions, characterized in that, when the computer program / instructions are executed by a processor, they implement the reciprocating compressor phase identification method described above.

[0158] Computer program products include computer programs or instruction sets used to perform specific tasks or achieve specific functions. These programs or instructions are designed to be executed by a processor to implement a series of predefined steps or operations. The program product may be stored in various forms of computer storage media, such as memory, hard disks, solid-state drives, optical discs, or other forms of digital storage devices. It may exist in the form of compiled binary code or in the form of scripts or bytecode that can be executed by an interpreter. Through carefully designed algorithms and logical instructions, the program product enables the processor to process data in a specific order and manner, performing various functions such as data analysis, user interaction, and device control.

[0159] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0160] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0161] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A phase identification method for a reciprocating compressor, characterized in that, include: Acquire dynamic pressure data of multi-cylinder bondless phase; The dynamic pressure data was divided into multiple data groups according to time sequence, and multiple data groups were selected for analysis. Determine the working process of the data set and identify two consecutive expansion start points to obtain the whole cycle of dynamic pressure data; Based on the initial structural design of the reciprocating compressor, the initial expansion angle difference between the inside and outside of the cylinder and the expansion angle difference between each stage of the cylinder are calculated using dynamic pressure data. If all angle differences are within the set range, the dynamic pressure data is normal, and the phase is identified as normal; if any angle difference is outside the set range, the dynamic pressure data is abnormal, and the phase is identified as abnormal.

2. The reciprocating compressor phase identification method according to claim 1, characterized in that, Methods for obtaining dynamic stress data include: Determine the speed fluctuation range N1~N2 of the reciprocating compressor; The longest working cycle is obtained based on the speed fluctuation range. Set the sampling time interval Δt, and the time length is xT max The continuous dynamic pressure data of the inner and outer sides of each cylinder are extracted, where x is a set constant; Obtain dynamic pressure data A = {D 11O D 11N ,...,D ijO D ijN }, where D is a data set continuously extracted according to the time sequence, i is the level, i = 1, 2, 3..., j is the sorting of different cylinders in the same level, j = 1, 2, 3..., O is the outer side of the cylinder body, and N is the inner side of the cylinder body.

3. The reciprocating compressor phase identification method according to claim 2, characterized in that, Methods for filtering multiple sets of analytical data using external dynamic pressure data include: Obtain the maximum value (max(D)) from the external dynamic pressure data. ijO ) and minimum value min(D ijO ), where D ijO ={p1,p2,…,p n } represents the dynamic pressure data on the outer side of the j-th cylinder in the i-th stage, p n This refers to the nth outermost data of the jth cylinder in the i-th stage; Determine the median of the lateral pressure Determine the neighborhood D of the median external pressure ijO-mid ={(p o )∣p o =(0.95~1.05)p midO }, where o is the data sequence number, and all data points in the neighborhood are traversed. If the data sequence numbers of two data points differ by 1, they are grouped into the same data group, resulting in multiple data groups. Sort multiple data sets by time series and select the middle M data sets consecutively.

4. The reciprocating compressor phase identification method according to claim 3, characterized in that, Dynamic pressure data includes both expansion and compression processes. For data points within the same data set, a judgment is made if p... o -p o-s ≤0&p o -p o+s If ≥0, then this data set is determined to be an expansion process; otherwise, this data set is a compression process. s = 1, 2, 3... are random numbers.

5. The reciprocating compressor phase identification method according to claim 4, characterized in that, Methods for filtering multiple sets of analytical data using internal dynamic pressure data include: Obtain the maximum value (max(D)) from the internal dynamic pressure data. ijN ) and minimum value min(D ijN ), where D ijN ={p1,p2,…,p m } represents the dynamic pressure data of the inner side of the j-th cylinder in the i-th stage, p m This refers to the m-th outermost data of the j-th cylinder in the i-th stage; Determine the median internal pressure Determine the neighborhood D of the median internal pressure. ijN-mid ={(p n )∣p n =(0.95~1.05)p midN }, where n is the data index, and all data points in the neighborhood are traversed. If the data indices of two data points differ by 1, they are grouped into the same data group, resulting in multiple data groups. Sort multiple data sets by time series and select the middle M data sets consecutively.

6. The reciprocating compressor phase identification method according to claim 5, characterized in that, Dynamic pressure data includes both expansion and compression processes. For data points within the same data set, a judgment is made if p... n -p n-s ≤0&p n -p n+s If ≥0, then this data set is determined to be an expansion process; otherwise, this data set is a compression process. s = 1, 2, 3... are random numbers.

7. The reciprocating compressor phase identification method according to claim 6, characterized in that, Methods for obtaining whole-cycle dynamic pressure data include: Filter the data set D from M data sets that is in the expansion process. d ; Choose any D d A data point p k Starting from k, numbers are continuously taken backwards until the previous data group D, which is in the compression process, is reached. d-1 ; Calculate the slope of adjacent data points Calculate the dynamic pressure data p for data with serial number kr. k-r Percentage difference from maximum dynamic pressure data Where, p max For maximum pressure data, p′ max This refers to the actual pressure in the exhaust pipe. If conditions one, two, and three are all satisfied simultaneously, then p is determined. k-r This is the starting point of the expansion; Condition 1: K r The slope of the last u1 data sets is negative, and the change does not exceed v1%. Condition 2: K r The slope of the first u2 data sets is either negative or positive, and the range of variation exceeds v2%. Condition 3: Δp r No more than v3%; Repeat the above steps to obtain data set D. d+2 The expansion starting point p l-r And obtain the integer period T=(lk)Δt of dynamic pressure data.

8. The reciprocating compressor phase identification method according to claim 7, characterized in that, The initial structural design of the reciprocating compressor is as follows: the outer dead center of the first-stage cylinder is 0 degrees, the outer dead center of the second-stage cylinder in the same cycle is 0+η1 degrees, the outer dead center of the third-stage cylinder in the same cycle is 0+η2 degrees, and so on, designed according to equal angles. The phase difference between the inner dynamic pressure data and the outer dynamic pressure data of the cylinder in the same cycle is 180 degrees. Obtain data set D for each stage of the cylinder d and data group D d+2 Corresponding inner expansion initiation point and outer expansion initiation point Where a, b, c, d, e, f, a1, b1, c1, d1 are all data sequence numbers; Calculate the initial expansion angle difference between the inside and outside of the cylinder. Where △m is the angle difference between two expansion points on the inner side of the m-stage cylinder, and △′m is the angle difference between two expansion points on the outer side of the m-stage cylinder; Calculate the difference in initial expansion angles between the two stages of cylinders.

9. A phase identification method for a reciprocating compressor according to claim 8, characterized in that, The set range for the initial expansion angle difference between the inner and outer sides of the cylinder is: The setting range for the difference between the two initial expansion angles of each cylinder is as follows:

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it implements a reciprocating compressor phase identification method as described in any one of claims 1-9.

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