A method for predicting compressor surge in gas turbine complete unit test

Abstract

The present application belongs to the technical field of compressor surge prediction in a gas turbine whole-machine test, and specifically relates to a method for predicting compressor surge in a gas turbine whole-machine test, comprising the following steps: first, obtaining the characteristics of a characteristic function Z at different compressor converted speeds nr25, and obtaining the peak values ​​of the characteristic function Z at different compressor converted speeds nr25, wherein #imgabs0#nr25 is the compressor converted speed, Pt25 is the compressor inlet total pressure, Pt3 is the compressor outlet total pressure, and P3m is the compressor outlet static pressure; second, in a gas turbine whole-machine test, measuring the compressor converted speed nr25, the compressor inlet total pressure Pt25, the compressor outlet total pressure Pt3, and the compressor outlet static pressure P3m; and third, calculating the characteristic function Z of the compressor in the gas turbine whole-machine test, and comparing the calculated characteristic function Z with the peak values ​​of the characteristic function Z at the corresponding compressor converted speed nr25 to obtain the surge margin of the compressor.

Description

Technical Field

[0001] The present application belongs to the technical field of compressor surge prediction for a gas turbine complete unit test run, and specifically relates to a method for predicting compressor surge for a gas turbine complete unit test run. Background Art

[0002] During the whole-unit test of a gas turbine, various factors may lead to insufficient compressor margin, which in turn may cause gas turbine surge and structural damage, seriously affecting the progress and safety of the whole-unit test. Therefore, during the whole-unit test of a gas turbine, it is necessary to monitor the compressor margin level at all times.

[0003] Due to the layout constraints of gas turbine full-unit run-in tests, only parameters such as compressor speed and pressure are often measured, making it difficult to accurately obtain compressor inlet flow. Therefore, current gas turbine full-unit run-in tests often indirectly measure compressor margin levels by combining the compressor speed-pressure ratio characteristic with the amplitude of the pulsating pressure fluctuations. This technical solution fails to consider the impact of compressor flow changes on the overall margin. In certain abnormal situations, the compressor flow characteristics may change, while the compressor speed-pressure ratio characteristics may not change significantly. However, the actual margin may decrease significantly, posing a risk of underreporting. This could mean that during a gas turbine full-unit run-in test, the compressor speed-pressure ratio characteristics may perform well, but the compressor may experience stall or even surge. Furthermore, while theoretically, analyzing the frequency characteristics of the pulsating pressure can detect compressor instability signals in advance, the time from the appearance of the frequency characteristics to the actual onset of surge can actually be as short as 0.2 seconds, or even tens of milliseconds, for sudden stalls. This insufficient reaction time for the control system makes it difficult to effectively and promptly address compressor surge and prevent it from actually occurring.

[0004] This application is proposed in view of the above-mentioned technical defects. Summary of the Invention

[0005] The purpose of this application is to provide a method for predicting compressor surge in a gas turbine whole-unit test run, so as to overcome or alleviate at least one of the known technical deficiencies.

[0006] The technical solution of this application is:

[0007] A method for predicting compressor surge during a gas turbine full-machine run-in test comprises:

[0008] Step 1: Obtain the characteristics of the characteristic function Z at different compressor conversion speeds nr25, and obtain the peak value of the characteristic function Z at different compressor conversion speeds nr25, where: nr25 is the converted compressor speed, Pt25 is the compressor inlet total pressure, Pt3 is the compressor outlet total pressure, and P3m is the compressor outlet static pressure;

[0009] Step 2: During the gas turbine full-machine test, the compressor converted speed nr25, the compressor inlet total pressure Pt25, the compressor outlet total pressure Pt3, and the compressor outlet static pressure P3m are measured;

[0010] Step 3: Calculate the characteristic function Z of the compressor during the gas turbine full-machine test, compare it with the peak value of the characteristic function Z at the corresponding compressor converted speed nr25, and obtain the surge margin of the compressor.

[0011] According to at least one embodiment of the present application, in the above-mentioned gas turbine whole-machine test compressor surge prediction method, in step one, the characteristics of the characteristic function Z at different compressor conversion speeds nr25 are obtained, which are specifically obtained by compressor component testing.

[0012] According to at least one embodiment of the present application, in the above-mentioned method for predicting compressor surge in a gas turbine whole-machine test, in step 2, the compressor outlet static pressure P3m is measured and specifically extracted from the pulsating static pressure.

[0013] According to at least one embodiment of the present application, in the above-mentioned method for predicting compressor surge in a gas turbine whole-unit test, in step 2, the compressor outlet static pressure P3m is measured, specifically obtained by measuring the wall static pressure.

[0014] According to at least one embodiment of the present application, in the above-mentioned method for predicting compressor surge in the gas turbine whole-unit test, in step three, the surge margin of the compressor is characterized by the size of the relative difference between the characteristic function Z of the compressor and the peak value of the characteristic function Z at the corresponding compressor converted speed nr25.

[0015] This application has at least the following beneficial technical effects:

[0016] A method for predicting compressor surge during a gas turbine full-unit run-in test is provided. By utilizing readily available test data from the gas turbine full-unit run-in test, a characteristic function Z is defined that reflects the effect of flow rate variations on the compressor surge margin. This function, taking compressor flow rate variations into account, evaluates the compressor surge margin during the gas turbine full-unit run-in test, and predicts compressor surge. Compared to technical solutions that indirectly measure the compressor margin level through the compressor speed-pressure ratio characteristic combined with the fluctuation amplitude of the pulsating pressure, this method is more quantitative and accurate, and has sufficient reaction time, enabling timely processing of compressor surge to prevent its actual occurrence. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of the method for predicting compressor surge in a gas turbine whole-machine test provided in an embodiment of the present application.

[0018] In order to better illustrate this embodiment, some contents of the drawings may be omitted. They are only used for illustrative purposes and should not be construed as limiting the present application. DETAILED DESCRIPTION

[0019] To make the technical solution and its advantages of this application more clear, the technical solution of this application will be further described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described here are only some of the embodiments of this application and are only used to explain this application, not to limit this application. It should be noted that for ease of description, only the parts relevant to this application are shown in the accompanying drawings, and other relevant parts can refer to the general design.

[0020] In addition, unless otherwise defined, the technical terms or scientific terms used in the description of this application should have the usual meanings understood by those skilled in the art in the field to which this application belongs. The words indicating orientation used in the description of this application are only used to indicate relative directions or positional relationships. When the absolute position of the described object changes, its relative positional relationship may also change accordingly. The word "include" used in the description of this application means that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, but does not exclude other elements or objects.

[0021] In addition, it should be noted that, unless otherwise clearly stipulated and limited, the words "installation", "connection" and similar terms used in the description of this application should be understood in a broad sense. For example, the connection can be a fixed connection or a detachable connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Technical personnel in the field can understand its specific meaning in this application according to the specific circumstances.

[0022] During the gas turbine complete unit test, based on the existing arrangement, it is easy to obtain the compressor converted speed nr25, the compressor inlet total pressure Pt25, the compressor outlet total pressure Pt3, and the compressor outlet static pressure P3m. Among them, the compressor outlet static pressure P3m can be extracted from the pulsating static pressure or obtained by measuring the wall static pressure.

[0023] Practice shows that for a specific compressor, the characteristic function is a function of the compressor conversion speed nr25. From the compressor component test, the characteristics of the characteristic function Z at different compressor conversion speeds nr25 can be obtained.

[0024] Figure 1This is the characteristic function Z obtained from a test of a certain compressor component. It can be seen that the characteristic function Z increases monotonically from 0.75 to 1.0, from near the operating point to near the surge point, as the compressor conversion speed nr25 increases, and the peak value of the characteristic function Z is related to the specific compressor. At the same conversion speed nr25, the change in the adjustable blade angle of the compressor within a certain range has little effect on the peak value of the characteristic function Z. At a fixed conversion speed nr25, the change in the characteristic function Z from near the operating point to near the surge point of the compressor represents the increase in the total pressure ratio and the decrease in the flow rate. Based on this, the present application provides a method for predicting compressor surge in a gas turbine whole-unit test. This method can be used without increasing the testing requirements under the existing gas turbine whole-unit test layout. In the absence of flow tests, the method utilizes the test data that is easily obtained from the gas turbine whole-unit test to consider the impact of flow changes on the compressor surge margin.

[0025] Step 1: Obtain the characteristics of the characteristic function Z at different compressor conversion speeds nr25, and obtain the peak value of the characteristic function Z at different compressor conversion speeds nr25, that is, the critical value when the compressor surges.

[0026] The characteristics of the characteristic function Z at different compressor conversion speeds nr25 are obtained, which can be specifically obtained from compressor component tests.

[0027] Step 2: During the gas turbine complete machine test, the compressor converted speed nr25, the compressor inlet total pressure Pt25, the compressor outlet total pressure Pt3, and the compressor outlet static pressure P3m are measured.

[0028] The compressor outlet static pressure P3m can be extracted from the pulsating static pressure or obtained by measuring the wall static pressure.

[0029] Step 3: Calculate the characteristic function Z of the compressor during the gas turbine full-machine test, compare it with the peak value of the characteristic function Z at the corresponding compressor converted speed nr25, and obtain the surge margin of the compressor.

[0030] If, during the whole-unit test of the gas turbine, the characteristic function Z of the compressor is greater than the peak value of the characteristic function Z at the corresponding compressor converted speed nr25, the compressor will surge. When the characteristic function Z of the compressor is less than the peak value of the characteristic function Z at the corresponding compressor converted speed nr25, the surge margin of the compressor can be characterized by the relative difference between the characteristic function Z of the compressor and the peak value of the characteristic function Z at the corresponding compressor converted speed nr25. When the surge margin of the compressor is less than the set threshold, corresponding processing is carried out in a timely manner to prevent the actual occurrence of surge and ensure the progress and safety of the whole-unit test of the gas turbine.

[0031] The method for predicting compressor surge during a gas turbine full-unit test disclosed in the above-mentioned embodiment utilizes test data that is easily obtained during a gas turbine full-unit test to define a characteristic function Z that can reflect the impact of flow rate changes on the compressor surge margin. This function takes compressor flow rate changes into consideration, evaluates the surge margin of the compressor during the gas turbine full-unit test, and predicts compressor surge. Compared to technical solutions that indirectly measure the compressor margin level through the speed-pressure ratio characteristics of the compressor combined with the fluctuation amplitude of the pulsating pressure, this method is more quantitative and accurate, and has sufficient response time to promptly handle compressor surge and prevent the actual occurrence of surge.

[0032] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other. In the absence of conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0033] So far, the technical solution of the present application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or replacements to the relevant technical features, and the technical solutions after these changes or replacements will fall within the scope of protection of the present application.

Claims

1. A method for predicting compressor surge during a gas turbine full-machine test, characterized in that: include: Step 1: Obtain the characteristics of the characteristic function Z at different compressor conversion speeds nr25, and obtain the peak value of the characteristic function Z at different compressor conversion speeds nr25, where: nr25 is the converted compressor speed, Pt25 is the compressor inlet total pressure, Pt3 is the compressor outlet total pressure, and P3m is the compressor outlet static pressure; Step 2: During the gas turbine full-machine test, the compressor converted speed nr25, the compressor inlet total pressure Pt25, the compressor outlet total pressure Pt3, and the compressor outlet static pressure P3m are measured; Step 3: Calculate the characteristic function Z of the compressor during the gas turbine full-machine test, compare it with the peak value of the characteristic function Z at the corresponding compressor converted speed nr25, and obtain the surge margin of the compressor.

2. The method for predicting compressor surge during a gas turbine full-machine test according to claim 1, characterized in that: In step 1, the characteristics of the characteristic function Z at different compressor conversion speeds nr25 are obtained, which are specifically obtained from compressor component tests.

3. The method for predicting compressor surge during a gas turbine full-machine test according to claim 1, characterized in that: In step 2, the compressor outlet static pressure P3m is measured and extracted from the pulsating static pressure.

4. The method for predicting compressor surge during a gas turbine full-machine test according to claim 1, wherein: In step 2, the compressor outlet static pressure P3m is measured, specifically by measuring the wall static pressure.

5. The method for predicting compressor surge in a gas turbine full-machine test according to claim 1, characterized in that: In step 3, the surge margin of the compressor is characterized by the relative difference between the characteristic function Z of the compressor and the peak value of the characteristic function Z at the corresponding compressor converted speed nr25.

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