原型可逆式水泵水輪機在水輪機工況下壓力脈動特性的試驗研究及分析
發(fā)布時間：2018-08-30 10:13
【摘要】：可逆式水泵水輪機集合了水泵與水輪機兩種功能,并廣泛應(yīng)用于抽水蓄能電站。由于水泵水輪機啟停迅速和工況變換靈活等優(yōu)點使得抽水蓄能電站能快速反應(yīng)與追蹤電網(wǎng)負荷變化,并對其進行高效率的削峰填谷,進而維持電力系統(tǒng)穩(wěn)定運行。近些年隨著大容量、高水頭水泵水輪機的出現(xiàn),機組啟停事故、廠房振動、并網(wǎng)困難、噪聲、葉片紋裂等一系列問題頻發(fā)。根據(jù)文獻調(diào)研發(fā)現(xiàn)在諸多問題起因中,壓力脈動是主要原因之一。因此有必要對可逆式機組過流通道內(nèi)的壓力脈動的傳播機制和幅頻特性進行深入的分析研究,為水泵水輪機的安全運行和水力設(shè)計提供可靠參考。為了研究國內(nèi)某抽水蓄能電站水泵水輪機組的水力特性和廠房的振動規(guī)律,對該電站原型機組在水輪機工況下進行了兩次變負荷試驗。其中,第一次試驗平均毛水頭為326.01m,第二次試驗平均毛水頭為316.23m。試驗過程中在過流通道內(nèi)的蝸殼進口(1個)、頂蓋(2個)和無葉區(qū)(2個)三個位置安置了四個壓力脈動測點,并用壓力傳感器搜集了機組運行過程中產(chǎn)生的壓力脈動信號。本文以壓力脈動信號分析為主,內(nèi)容如下。首先,對第一次試驗中的壓力信號進行時域分析,著重對比了不同測點位置壓力脈動的強弱及其隨負荷的變化情況。分析結(jié)果如下:無葉區(qū)測點處的壓力脈動幅值最大,壓力信號沿著流道向上游傳播,并且延伸距離越遠,幅值越小;隨著機組負荷的提升,各個測點的壓力脈動幅值呈現(xiàn)先減小后增大的趨勢,且無量綱負荷為0.8時達到最小值,此時流態(tài)相對最好,運行最為安全穩(wěn)定。第二,對第一次試驗中的壓力信號利用進行FFT變換,并分析壓力脈動的頻域特性。分析結(jié)果如下:壓力脈動信號中9倍葉輪轉(zhuǎn)頻和18倍葉輪轉(zhuǎn)頻成分占主導(dǎo),且均產(chǎn)生于無葉區(qū),同時這兩個特征頻率下的壓力脈動是造成廠房振動的主要原因;隨著負荷的提升,以上兩中成分的壓力脈動呈現(xiàn)出不同的變化規(guī)律,9倍葉輪轉(zhuǎn)頻下的壓力脈動幅值隨著負荷的提升逐漸減小,而18倍葉輪轉(zhuǎn)頻下的壓力脈動幅值隨著負荷的提升先減小后增大。第三,對第二次試驗中的壓力脈動信號進行如上幅頻特性分析,并與第一次試驗數(shù)據(jù)進行對比,探討壓力脈動與機組運行水頭的關(guān)系。分析結(jié)果如下:在高水頭工況下,蝸殼進口和頂蓋區(qū)域的壓力脈動幅值相對較小,內(nèi)部流動相對較穩(wěn)定;在低水頭工況下,無葉區(qū)2個測點處的壓力脈動幅值相對較小,內(nèi)部流動相對較穩(wěn)定;值得注意的是,壓力信號的頻率不會因為水頭的變動而產(chǎn)生變化。
[Abstract]:Reversible pump turbine has two functions: pump and turbine, and it is widely used in pumped storage power station. Due to the advantages of quick start and stop of pump turbine and flexible change of working conditions, pumped storage power station can quickly respond and track the change of power network load, and carry out high efficiency peak cutting and valley filling so as to maintain the stable operation of power system. In recent years, with the emergence of large capacity, high head water pump turbine, unit start and stop accident, plant vibration, grid-connection difficulty, noise, blade crack and a series of problems occurred frequently. According to literature investigation, it is found that pressure fluctuation is one of the main causes of many problems. Therefore it is necessary to analyze the propagation mechanism and amplitude-frequency characteristics of pressure pulsation in the flow passage of reversible generating units in order to provide reliable reference for the safe operation and hydraulic design of pump turbines. In order to study the hydraulic characteristics of the pump turbine unit and the vibration law of the workshop in a domestic pumped storage power station, two variable load tests were carried out on the prototype unit of the power station under the working conditions of the turbine. The average water head of the first experiment was 326.01 m, and that of the second experiment was 316.23 m. During the test, four pressure pulsation measuring points were placed at the inlet of the volute (1), the top (2) and the leafless zone (2) in the flow passage, and the pressure pulsation signals produced during the operation of the unit were collected by the pressure sensor. In this paper, the pressure pulsation signal analysis is the main, the content is as follows. Firstly, the pressure signal in the first test is analyzed in time domain, and the pressure fluctuation at different measuring points and its variation with load are compared. The results are as follows: the amplitude of pressure pulsation is the largest at the measuring point in the leafless area, and the pressure signal propagates upstream along the channel, and the farther the distance is, the smaller the amplitude is; with the increase of the unit load, The pressure fluctuation amplitude of each measuring point decreases first and then increases, and reaches the minimum value when the dimensionless load is 0.8, the flow state is relatively best and the operation is the most safe and stable. Secondly, the pressure signal in the first test is transformed by FFT, and the frequency characteristic of pressure fluctuation is analyzed. The results are as follows: in the pressure pulsation signal, 9 times impeller rotation frequency and 18 times impeller rotation frequency component are dominant, and both of them are produced in the leafless region, and the pressure pulsation at these two characteristic frequencies is the main cause of the powerhouse vibration. With the increase of load, the pressure pulsation of the above two components presents different variation laws, and the amplitude of pressure pulsation decreases gradually with the increase of load, and the amplitude of pressure pulsation decreases with the increase of load. However, the amplitude of pressure pulsation decreases first and then increases with the increase of load at the rotating frequency of 18 times impeller. Thirdly, the pressure pulsation signal in the second test is analyzed such as amplitude and frequency characteristic, and compared with the data of the first test, the relationship between the pressure pulsation and the running water head of the unit is discussed. The results are as follows: under the condition of high water head, the amplitude of pressure pulsation is relatively small and the internal flow is relatively stable at the inlet of volute and the top cover, and the amplitude of pressure pulsation is relatively small at the two measuring points in the leafless zone under the condition of low head. The internal flow is relatively stable; it is worth noting that the frequency of pressure signals does not change with the change of water head.
【學(xué)位授予單位】：華北電力大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV734.1
本文編號：2212764
[Abstract]:Reversible pump turbine has two functions: pump and turbine, and it is widely used in pumped storage power station. Due to the advantages of quick start and stop of pump turbine and flexible change of working conditions, pumped storage power station can quickly respond and track the change of power network load, and carry out high efficiency peak cutting and valley filling so as to maintain the stable operation of power system. In recent years, with the emergence of large capacity, high head water pump turbine, unit start and stop accident, plant vibration, grid-connection difficulty, noise, blade crack and a series of problems occurred frequently. According to literature investigation, it is found that pressure fluctuation is one of the main causes of many problems. Therefore it is necessary to analyze the propagation mechanism and amplitude-frequency characteristics of pressure pulsation in the flow passage of reversible generating units in order to provide reliable reference for the safe operation and hydraulic design of pump turbines. In order to study the hydraulic characteristics of the pump turbine unit and the vibration law of the workshop in a domestic pumped storage power station, two variable load tests were carried out on the prototype unit of the power station under the working conditions of the turbine. The average water head of the first experiment was 326.01 m, and that of the second experiment was 316.23 m. During the test, four pressure pulsation measuring points were placed at the inlet of the volute (1), the top (2) and the leafless zone (2) in the flow passage, and the pressure pulsation signals produced during the operation of the unit were collected by the pressure sensor. In this paper, the pressure pulsation signal analysis is the main, the content is as follows. Firstly, the pressure signal in the first test is analyzed in time domain, and the pressure fluctuation at different measuring points and its variation with load are compared. The results are as follows: the amplitude of pressure pulsation is the largest at the measuring point in the leafless area, and the pressure signal propagates upstream along the channel, and the farther the distance is, the smaller the amplitude is; with the increase of the unit load, The pressure fluctuation amplitude of each measuring point decreases first and then increases, and reaches the minimum value when the dimensionless load is 0.8, the flow state is relatively best and the operation is the most safe and stable. Secondly, the pressure signal in the first test is transformed by FFT, and the frequency characteristic of pressure fluctuation is analyzed. The results are as follows: in the pressure pulsation signal, 9 times impeller rotation frequency and 18 times impeller rotation frequency component are dominant, and both of them are produced in the leafless region, and the pressure pulsation at these two characteristic frequencies is the main cause of the powerhouse vibration. With the increase of load, the pressure pulsation of the above two components presents different variation laws, and the amplitude of pressure pulsation decreases gradually with the increase of load, and the amplitude of pressure pulsation decreases with the increase of load. However, the amplitude of pressure pulsation decreases first and then increases with the increase of load at the rotating frequency of 18 times impeller. Thirdly, the pressure pulsation signal in the second test is analyzed such as amplitude and frequency characteristic, and compared with the data of the first test, the relationship between the pressure pulsation and the running water head of the unit is discussed. The results are as follows: under the condition of high water head, the amplitude of pressure pulsation is relatively small and the internal flow is relatively stable at the inlet of volute and the top cover, and the amplitude of pressure pulsation is relatively small at the two measuring points in the leafless zone under the condition of low head. The internal flow is relatively stable; it is worth noting that the frequency of pressure signals does not change with the change of water head.
【學(xué)位授予單位】：華北電力大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV734.1
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