Method and device for detecting pressure of expansion tank for closed circuit system

Abstract

This application discloses a pressure detection method and apparatus for an expansion tank in a closed-loop circulation system. The pressure detection method in this application includes: acquiring the standard pressure P0, standard volume V0, and standard temperature T0 of the gas in the expansion tank under standard conditions; acquiring the first pressure P1 and first temperature T1 of the gas in the expansion tank under the test condition; controlling the opening of the drain pipe of the expansion tank under the test condition; acquiring the volume of liquid discharged from the expansion tank, and when the discharged liquid volume is Vw, the expansion tank enters a transition state; acquiring the second pressure P2 of the gas in the expansion tank under the transition state; and determining the pressure based on the first pressure P1, the second pressure P2, the first temperature T1, and the discharged liquid volume Vw. W Given standard pressure P0, standard volume V0, and standard temperature T0, determine the first standard pressure P of the gas under the test conditions. 1t The monitoring method provided in this application can test the pressure of gas inside an expansion tank. It is simple to operate and has high detection efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cooling equipment, in particular to a pressure detection method and device for an expansion tank of a closed circulation system and a wind turbine generator. BACKGROUND

[0002] During the operation of large electronic equipment, a large amount of heat is generated, and a circulation system is usually used to exchange heat and reduce the temperature. Or when the temperature is too low, the circulation system is used to heat it to ensure its normal operation. At present, the closed circulation cooling system using liquid medium as the cooling medium is widely used. This equipment brings the cooling medium into the electronic component radiator through the water pump to exchange heat and take away the heat, so as to reduce the temperature of the electronic component. However, the volume of the cooling medium will expand or shrink with the change of temperature, so it is necessary to connect a pressure stabilizing device in the circulation system.

[0003] The existing pressure stabilizing device generally includes an expansion tank, and the expansion tank has two closed chambers for storing medium and pressure maintaining gas. During the operation of the expansion tank, the volume of the pressure maintaining gas may change, so it is necessary to detect it to keep the standard pressure when it leaves the factory. SUMMARY

[0004] The embodiment of the present application provides a pressure detection method and device for an expansion tank of a closed circulation system and a wind turbine generator, which can test the pressure of gas in the expansion tank, and the operation method is simple and the detection efficiency is high.

[0005] In a first aspect, the embodiment of the present application provides a pressure detection method for an expansion tank of a closed circulation system. The expansion tank stores liquid and gas in a to-be-detected state. The pressure detection method comprises the following steps: obtaining a standard pressure P0, a standard volume V0 and a standard temperature T0 of gas in the expansion tank in a standard state; obtaining a first pressure P1 and a first temperature T1 of gas in the expansion tank in the to-be-detected state; controlling a liquid discharge pipeline of the expansion tank in the to-be-detected state to be open; obtaining a volume of discharged liquid, and when the volume of the discharged liquid is Vw, the liquid discharge pipeline is controlled to be closed, and the expansion tank becomes a transition state; obtaining a second pressure P2 of gas in the expansion tank in the transition state; and determining a first standard pressure P of gas in the to-be-detected state according to the first pressure P1, the second pressure P2, the first temperature T1, the volume Vw of the discharged liquid, the standard pressure P0, the standard volume V0 and the standard temperature T0. W 1t .

[0006] According to an aspect of the embodiment of the present application, the volume difference Vq of gas in the to-be-detected state and the transition state in the expansion tank is equal to the volume Vw of the discharged liquid.

[0007] ​According to one aspect of the present invention, based on a first pressure P1, a second pressure P2, a first temperature T1, and a discharged liquid volume V... W Using standard pressure P0, standard volume V0, and standard temperature T0, the first standard pressure P of the gas inside the expansion tank under the test condition is obtained. 1t This includes: based on the first pressure P1, the second pressure P2, and the volume of liquid discharged V. W Obtain the first gas volume V1 of the gas to be measured; based on the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0, and the standard temperature T0, obtain the first standard pressure P of the gas to be measured. 1t .

[0008] According to one aspect of the present invention, based on the first pressure P1, the second pressure P2, and the discharged liquid volume V W Calculate the first gas volume V1 of the expansion tank under the test condition, including determining the first gas volume V1 by the following formula.

[0009]

[0010] According to one aspect of the present invention, the first standard pressure P of the expansion tank under the test state is obtained based on the first gas volume V1, the standard pressure P0, and the standard gas volume V0. 1t This includes determining the first standard pressure P using the following formula. 1t ,

[0011]

[0012] According to one aspect of the present invention, it further includes: controlling the opening of the replenishment pipeline of the expansion tank to inject liquid of volume Vw into the expansion tank; according to a first standard pressure P 1t And the first pressure P1, obtain the pressure difference Pw, where Pw=|P1-P 1t |; Gas is added to or discharged from the expansion tank according to the pressure difference Pw.

[0013] According to one aspect of the present invention, replenishing or discharging gas into an expansion tank based on a pressure difference Pw includes: obtaining an allowable deviation ΔP of the expansion tank; determining whether the pressure difference Pw exceeds the allowable deviation ΔP, wherein Pw > ΔP and P1 > P 1t Under the condition of +ΔP, control the opening of the gas supply line of the expansion tank to allow the gas in the expansion tank to be discharged until the pressure in the expansion tank reaches Pw≤ΔP; or under the condition of Pw>ΔP and P1<P 1t Under the condition of -ΔP, the gas supply line of the expansion tank is opened to replenish gas into the expansion tank until the pressure in the expansion tank reaches Pw≤ΔP.

[0014] According to an aspect of the embodiment of the present application, before the step of obtaining the first pressure P1 of the gas in the expansion tank in the to-be-tested state, the method further comprises: controlling the liquid supplement pipeline, the liquid discharge pipeline and the gas transmission pipeline of the expansion tank in the to-be-tested state to be closed.

[0015] According to an aspect of the embodiment of the present application, the first temperature T1 of the gas in the expansion tank in the to-be-tested state is obtained by: obtaining the temperature Tq of the liquid flowing out of the expansion tank in the to-be-tested state; obtaining the ambient temperature Tg of the environment in which the expansion tank is located; and obtaining the first temperature T1 of the gas in the expansion tank in the to-be-tested state according to the calculation formula T1=(Tq+Tg) / 2.

[0016] In a second aspect, the embodiment of the present application provides a pressure detection device for an expansion tank of a closed circulation system, which is used to implement the pressure detection method in the above-mentioned embodiment. The pressure detection device comprises: a liquid storage device, which comprises a liquid discharge pipeline, a liquid storage tank and a first switch valve, wherein the two ends of the liquid discharge pipeline are respectively connected to the liquid inlet of the liquid storage tank and the liquid connection port of the expansion tank, and the first switch valve is arranged on the liquid discharge pipeline; a first temperature detection device arranged in the environment in which the expansion tank is located, which is used to detect the ambient temperature of the environment; a pressure detection device arranged at the gas connection port of the expansion tank, which is used to detect the first pressure P1 of the gas in the expansion tank in the to-be-tested state and the second pressure P2 of the gas in the expansion tank in the transition state; and a flow detection device and a second temperature detection device arranged on the liquid discharge pipeline, wherein the flow detection device is used to detect the volume of the liquid flowing out of the expansion tank, and the second temperature detection device is used to detect the temperature of the liquid flowing out of the expansion tank in the to-be-tested state.

[0017] According to an aspect of the embodiment of the present application, the pressure detection device further comprises a controller, which is used to control the opening or closing of the first switch valve, to make the liquid discharge pipeline of the expansion tank in the to-be-tested state conductive or closed, and to determine the first standard pressure P W of the gas in the to-be-tested state according to the first pressure P1, the second pressure P2, the first temperature T1, the volume Vw of the liquid flowing out, the standard pressure P0, the standard volume V0 and the standard temperature T0. 1t

[0018] According to an aspect of the embodiment of the present application, the controller is used to obtain the first gas volume V1 of the gas in the to-be-tested state according to the first pressure P1, the second pressure P2 and the volume Vw of the liquid flowing out.

[0019] According to an aspect of the embodiment of the present application, the controller is used to obtain the first standard pressure P 1t of the gas in the to-be-tested state according to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0 and the standard temperature T0.

[0020] According to an aspect of the embodiment of the present application, the controller is used to determine the first gas volume V1 by the following formula: ​

[0021]

[0022] According to an aspect of the embodiment of the present application, the controller determines the first standard pressure P 1t ,

[0023]

[0024] According to an aspect of the embodiment of the present application, the pressure detection device further comprises a liquid supplementing device, the liquid supplementing device comprising a liquid supplementing pipeline, a liquid supplementing pump and a second switch valve, wherein two ends of the liquid supplementing pipeline are connected to the outlet of the liquid storage tank and the liquid connecting port of the expansion tank respectively; the liquid supplementing pump and the second switch valve are arranged on the liquid supplementing pipeline; the controller is further configured to control the second switch valve to open, so that the liquid supplementing pipeline of the expansion tank is conducted, and the liquid with the volume of Vw is injected into the expansion tank.

[0025] According to an aspect of the embodiment of the present application, the pressure detection device further comprises a gas supplementing device, the gas supplementing device comprising a filter, a gas supplementing pump, a third switch valve and a gas pipeline, the filter is configured to be connected to a gas source, two ends of the gas pipeline are connected to the filter and the gas connecting port of the expansion tank respectively, the gas supplementing pump and the third switch valve are arranged on the gas pipeline; the controller is further configured to obtain the allowable deviation ΔP of the expansion tank; obtain the pressure difference Pw according to the first standard pressure P 1t and the first pressure P1, wherein Pw = |P1-P 1t |; determine whether the pressure difference Pw exceeds the allowable deviation ΔP, in the case of Pw > ΔP and P1 > P 1t + ΔP, control the third switch valve to open, so that the gas pipeline of the expansion tank is conducted, and the gas in the expansion tank is discharged until the pressure in the expansion tank reaches Pw ≤ ΔP; or in the case of Pw > ΔP and P1 < P 1t - ΔP, control the third switch valve to open and the gas supplementing pump to start, so that the gas pipeline of the expansion tank is conducted, and the gas is supplemented into the expansion tank until the pressure in the expansion tank reaches Pw ≤ ΔP.

[0026] According to an aspect of the embodiment of the present application, the controller is configured to obtain the liquid temperature Tq of the liquid flowing out of the expansion tank in the to-be-measured state; obtain the ambient temperature Tg of the environment in which the expansion tank is located in the to-be-measured state; and obtain the first temperature T1 of the gas in the expansion tank in the to-be-measured state according to the calculation formula T1 = (Tq + Tg) / 2.

[0027] According to an aspect of the embodiment of the present application, the gas supplementing device further comprises a buffer tank connected to the gas pipeline, the buffer tank is arranged between the third switch valve and the gas supplementing pump.

[0028] In a third aspect, the present application provides a wind turbine, comprising a closed cycle system and the pressure detection device for the expansion tank of the closed cycle system according to any one of the above embodiments, wherein the liquid outlet of the expansion tank is provided with a fourth switch valve, the gas connection port of the expansion tank is provided with a fifth switch valve, the liquid discharge pipeline and the liquid inlet pipeline of the pressure detection device are detachably connected with the fourth switch valve, and the gas delivery pipeline is detachably connected with the fifth switch valve.

[0029] In the pressure detection method for the expansion tank of the closed cycle system, the difference between the gas volume in the to-be-detected state and the gas volume in the transition state is measured, and the corresponding pressure and temperature in the to-be-detected state and the transition state are measured, so as to calculate the standard pressure value that the gas needs to reach in the to-be-detected state. The above method is to obtain the standard pressure value that the gas needs to reach in the to-be-detected state by measuring the easily-obtained parameters and by formula conversion, thereby avoiding the operation of discharging a large amount of cooling medium and the repeated operation of liquid injection and gas discharge after detecting the pre-charging pressure of the expansion tank, reducing the workload, improving the system operation reliability, and improving the detection accuracy and efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0030] The features, advantages, and technical effects of the exemplary embodiments of the present application will be described below with reference to the accompanying drawings.

[0031] Figure 1 is a structural schematic diagram of a closed cycle system;

[0032] Figure 2 is a structural schematic diagram of an expansion tank for a closed cycle system;

[0033] Figure 3 is a flowchart of a pressure detection method for an expansion tank of a closed cycle system according to an embodiment of the present application;

[0034] Figure 4 is a structural schematic diagram of a pressure detection device for an expansion tank of a closed cycle system in a to-be-detected state according to an embodiment of the present application;

[0035] Figure 5 is Figure 4 is a structural schematic diagram of a pressure detection device for an expansion tank of a closed cycle system in a transition state;

[0036] Figure 6 is a flowchart of determining a first standard pressure of gas in a to-be-detected state in a pressure detection method for an expansion tank of a closed cycle system according to an embodiment of the present application;

[0037] Figure 7is a flow chart of a method for determining the pressure difference of the gas in the to-be-measured state in the pressure detection method for the expansion tank of the closed circulation system according to an embodiment of the present application;

[0038] Figure 8 is a flow chart of a method for determining whether to supplement or release the gas for the expansion tank in the to-be-measured state in the pressure detection method for the expansion tank of the closed circulation system according to an embodiment of the present application;

[0039] Figure 9 is a flow chart of a method for controlling the state of the expansion tank in the pressure detection method for the expansion tank of the closed circulation system according to an embodiment of the present application;

[0040] Figure 10 is a connection diagram of a controller in the pressure detection device for the expansion tank of the closed circulation system according to an embodiment of the present application;

[0041] Figure 11 is a structural diagram of the pressure detection device for the expansion tank of the closed circulation system according to another embodiment of the present application;

[0042] Figure 12 is a structural diagram of the pressure detection device according to an embodiment of the present application.

[0043] wherein:

[0044] 100, a pressure detection device for an expansion tank of a closed circulation system; 200, the expansion tank; 300, a water pump; 400, a heat source; A, an inlet; B, a liquid connection port; C, an outlet;

[0045] 10, a liquid storage device; 101, a liquid discharge pipeline; 102, a liquid storage tank; 103, a first switch valve; 104, a fourth switch valve;

[0046] 20, a detection device; 201, a first temperature detection device; 202, a pressure detection device; 203, a flow detection device; 204, a second temperature detection device;

[0047] 30, a controller;

[0048] 40, a liquid supplementing device; 401, a liquid supplementing pipeline; 402, a liquid supplementing pump; 403, a second switch valve;

[0049] 50, a gas supplementing device; 501, a filter; 502, a gas supplementing pump; 503, a third switch valve; 504, a gas pipeline; 505, a fifth switch valve; 506, a buffer tank;

[0050] In the drawings, the same components are designated by the same reference numerals. The drawings are not drawn according to the actual proportions. DETAILED DESCRIPTION

[0051] Features and exemplary embodiments of various aspects of the present application will be described below in detail. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without some of these specific details. The description of the embodiments is merely intended to provide a more detailed understanding of the present application. In the drawings and description below, well-known structures and techniques have not been shown in order to avoid obscuring the application; and, for clarity, some structures can be exaggerated. Furthermore, features, structures or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0052] The orientation words appearing in the following description are the directions shown in the drawings, and are not intended to limit the specific structure of the present application. In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be directly connected, or indirectly connected. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0053] The wind turbine is a mechatronic device for converting wind energy into electrical energy, which includes a variable pitch system, a yaw system, a main control system, a variable flow system and a water cooling system. The control core of the wind turbine is the variable flow system, which adjusts the state of the unit according to the parameters such as wind speed and wind direction detected by the sensor, and realizes automatic control of power generation. The core component in the variable flow system is affected by temperature in operation efficiency, and when the temperature is too high or too low, the operation efficiency will be low. Therefore, in the wind turbine, the main function of the circulating system is to cool or heat the IGBT of the variable flow system, so as to maintain normal operation efficiency and reduce failure.

[0054] The wind turbine is generally set in the wild, so it is usually cooled or heated by a closed circulating system. As shown in Figure 1 The closed circulating system usually includes an expansion tank 200, a water pump 300, a heat source (for heating or cooling the medium in the system) 400 and a heat exchanger 500 (usually connected with the variable flow system of the wind turbine, for heat exchange of the variable flow system). In the closed circulating system, the medium is usually liquid, and its thermal expansion and contraction effect is obvious. Therefore, an expansion tank is usually added in the circulating system to buffer the change of liquid volume and pressure in the closed circulating system, and to maintain the stability of the system.

[0055] As shown in Figure 2As shown, the expansion tank 200 in the closed circulation system generally uses a gas bag type or diaphragm type expansion tank. Moreover, the gas in the expansion tank has a certain standard pressure and standard volume at the factory, and the manufacturer will also provide the corresponding standard working condition gas temperature, gas volume and gas pressure data at the factory.

[0056] Figure 2 As shown in the middle, the expansion tank 200 is in a pre-charge pressure state, the expansion tank volume is V0, and the pre-charge pressure is P0, which corresponds to the pre-charge gas temperature T0. The design pre-charge state is usually provided by the expansion tank 200 supplier, and the expansion tank supplier pre-charge pressure is without medium in the expansion tank, and all is pre-charge gas.

[0057] After the closed circulation system is assembled, the system is filled with medium, and the pre-charge gas in the expansion tank 200 will be compressed after the system is filled, so a certain volume of medium will be filled, for example, the medium filled in the expansion tank 200 usually accounts for about 40% of the total volume V0 of the expansion tank 200, and the proportion of different system designs is not the same, which is not limited here.

[0058] The existing method for detecting the gas pressure of the expansion tank 200 in the working state generally has two kinds, the first method is to directly measure whether the pre-charge pressure value of the expansion tank 200 in the to-be-measured state reaches the standard, and to adjust the gas pressure of the expansion tank 200 according to the directly tested data. The second method is to close the valves before and after the pump station, empty the medium in the expansion tank 200 and the water pump 300, and then detect the pre-charge pressure of the expansion tank 200.

[0059] However, the existing technology cannot realize the convenient operation of pressure detection while ensuring the accuracy of measurement.

[0060] To solve the above technical problems, the application provides a new method for detecting the pressure of an expansion tank 200 in a closed circulation system. First, the detection method of the application does not need to completely empty the liquid in the expansion tank 200, thus omitting the subsequent operations of liquid injection and air exhaust of the pump station, reducing the workload, lowering the energy consumption, and improving the detection efficiency. Moreover, the method of the application reduces the volume of the liquid in the expansion tank 200 in the to-be-detected state by a part to convert to a transition state, measures the gas pressure, temperature, and liquid volume in the expansion tank 200 in the to-be-detected state and the transition state, converts the data in combination with the ideal gas equation and the gas pressure, temperature, and volume of the expansion tank 200 in the standard state, and more accurately obtains the standard pressure corresponding to the gas mass of the expansion tank 200 in the to-be-detected state, so as to obtain the accurate value of the pre-charge pressure adjustment according to the detection value of the gas of the expansion tank 200 in the to-be-detected state and the standard pressure corresponding thereto, the test result is accurate and the efficiency is high. Thus, the pre-charge pressure adjustment error is effectively avoided, the gas bag or diaphragm of the expansion tank 200 is prevented from failing, the service life of the expansion tank 200 is effectively prolonged, the buffering effect is improved, and the normal and reliable operation of the closed circulation system is ensured.

[0061] In summary, the method for detecting the pressure of the expansion tank 200 in the closed circulation system of the application has simple operation and high test detection efficiency.

[0062] In order to better understand the application, the following describes the application in detail Figures 3 to 11 The method for detecting the pressure of the expansion tank 200 in the closed circulation system of the application is described in detail.

[0063] Reference Figures 3 to 5 , wherein Figure 3 is a flow chart of the method for detecting the pressure of the expansion tank 200 in the closed circulation system according to an embodiment of the application, Figure 4 is a structural schematic diagram of a pressure detection device for the expansion tank 200 in the closed circulation system in a to-be-detected state according to an embodiment of the application, Figure 5 is Figure 4 is a structural schematic diagram of a pressure detection device for the expansion tank 200 in the closed circulation system in a transition state.

[0064] As Figure 3 shown, the method for detecting the pressure of the expansion tank 200 in the closed circulation system provided by the application specifically includes the following steps:

[0065] S1, obtaining a standard pressure P0, a standard volume V0, and a standard temperature T0 of gas of the expansion tank 200 in a standard state;

[0066] The expansion tank 200 can be a gas bag type or a diaphragm type, the standard state can be a factory state of the expansion tank 200, and the standard pressure P0, the standard volume V0 and the standard temperature T0 can be factory design parameters of the expansion tank 200. The standard pressure P0, the standard volume V0 and the standard temperature T0 are determined according to different circulating system requirements.

[0067] S2, a first pressure P1 and a first temperature T1 of the gas in the expansion tank 200 in the to-be-measured state are obtained.

[0068] The first pressure P1 in the to-be-measured state can be detected by the pressure detection device 202 arranged on the gas connection port of the expansion tank 200.

[0069] S3, the liquid discharge pipeline 101 of the expansion tank 200 in the to-be-measured state is controlled to be open;

[0070] S4, the volume of the liquid discharged from the expansion tank 200 is obtained, when the volume of the liquid discharged is Vw, the liquid discharge pipeline 101 is controlled to be closed, and the expansion tank 200 becomes a transition state.

[0071] In the above steps, the volume Vw of the liquid discharged should be less than the volume L1 of the original liquid in the expansion tank 200 in the to-be-measured state, so as to ensure that there is also liquid L2 and gas V2 stored in the expansion tank 200 in the transition state. The expansion tank 200 discharges the liquid with the volume Vw, so the volume of the liquid in the expansion tank 200 between the to-be-measured state and the transition state is different by Vw. Since the total volume in the expansion tank 200 is constant, after the liquid is discharged, the volume of the gas in the expansion tank 200 is correspondingly expanded, so when the volume Vw of the liquid is discharged, the volume of the gas is correspondingly expanded by the volume Vw. Therefore, the difference between the volume of the gas in the transition state and the volume of the gas in the to-be-measured state is Vw.

[0072] S5, a second pressure P2 of the gas in the expansion tank 200 in the transition state is obtained.

[0073] The second pressure P2 can also be detected by the pressure detection device 202 arranged on the gas connection port of the expansion tank 200.

[0074] S6, the first standard pressure P of the gas in the to-be-measured state is determined according to the first pressure P1, the second pressure P2, the first temperature T1, the volume Vw of the discharged liquid, the standard pressure P0, the standard volume V0 and the standard temperature T0. W 1t .

[0075] ​The pressure detection method for the expansion tank 200 in the closed circulation system provided by the embodiment of the present application measures the difference Vw of the gas volume of the expansion tank 200 in the to-be-detected state and the transition state, and the first pressure P1, the second pressure P2 and the first temperature T1 corresponding to the to-be-detected state and the transition state, and calculates the standard pressure P0 required by the gas in the to-be-detected state, in combination with the standard pressure P0, the standard volume V0 and the standard temperature T0 in the standard state. 1t .

[0076] The detection method of the present application does not need to completely empty the liquid in the expansion tank 200, so the subsequent operation of injecting liquid and exhausting gas to the pump station is omitted, the workload is reduced, the energy consumption is reduced, and the detection efficiency is improved. Moreover, the detection method of the present application converts the volume reduction Vw of the liquid in the expansion tank 200 in the to-be-detected state to the transition state, measures the first pressure P1, the second pressure P2 and the first temperature T1 in the to-be-detected state and the transition state, and calculates the standard pressure P0 required by the gas in the to-be-detected state in combination with the standard pressure P0, the standard volume V0 and the standard temperature T0 in the standard state and the ideal gas equation, so that the standard pressure P0 corresponding to the gas mass of the expansion tank 200 in the to-be-detected state is more accurately obtained. 1t , so that whether the pre-charge pressure should be adjusted and the accurate value of the pre-charge pressure adjustment can be more accurately determined according to the detection value P1 of the gas in the expansion tank 200 in the to-be-detected state and the standard pressure P 1t that should correspond to it, the test result is accurate and the efficiency is high. Therefore, the pre-charge pressure adjustment error is effectively avoided, the gas bag or diaphragm of the expansion tank 200 is prevented from failing, the service life of the expansion tank 200 is effectively prolonged, the buffering effect is improved, and the normal and reliable operation of the closed circulation system is ensured. In summary, the pressure detection method for the expansion tank 200 in the closed circulation system of the present application is simple in operation and high in test detection efficiency.

[0077] As an optional implementation, the gas volume difference Vq of the to-be-detected state and the transition state in the expansion tank 200 is equal to the discharged liquid volume Vw. As shown in Figure 4 and Figure 5 , the to-be-detected state of the liquid and the gas in the expansion tank 200 is shown in Figure 4 , the to-be-detected state of the liquid and the gas in the expansion tank 200 is shown in Figure 5 , the to-be-detected state of the liquid and the gas in the expansion tank 200 is shown in. It can be understood that the above-mentioned figures shown in the above-mentioned figures are only an example and do not represent the accurate volume of the liquid and the gas in the expansion tank 200.

[0078] As shown in Figure 4 and Figure 5 , the volume of the liquid in the to-be-detected state is L1, and the volume of the liquid in the transition state is L2.

[0079] In the embodiment, it is assumed that the total volume of the expansion tank 200 is V, the volume of the gas is Vg, and the volume of the liquid is Vq, so V=Vg+Vq. When the discharged liquid volume is Vw, the volume of the liquid in the expansion tank 200 is reduced by Vw, and the sum of the volumes of the gas and the liquid is unchanged, so the volume of the gas is relatively increased by Vw. It is assumed that the first gas volume is V1 and the second volume is V2, so V2-V1=Vw (1).

[0080] L1-L2=V2-V1=Vw (1).

[0081] In the above technical solution, by measuring the volume change of the liquid in the expansion tank 200, the volume change of the gas in the expansion tank 200 can be obtained, and the measurement method is relatively simple and the result is accurate.

[0082] According to one aspect of an embodiment of the present application, reference will be made to Figure 6 , and the step S6 comprises:

[0083] S61, obtaining the first gas volume V1 of the gas in the to-be-measured state according to the first pressure P1, the second pressure P2, and the discharged liquid volume Vw;

[0084] The first gas volume V1 is the volume of the gas in the expansion tank 200 in the to-be-measured state, and the volume V1 is determined as the first standard pressure P0 of the gas of the standard mass in the first gas volume state. 1t

[0085] S62, obtaining the first standard pressure P1 of the gas in the to-be-measured state expansion tank 200 according to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0, and the standard temperature T0. In other words, the first standard pressure P1 is the standard pressure corresponding to the mass of the gas in the standard state in the to-be-measured state. 1t 1t

[0086] As an optional implementation, in the step S61, the first gas volume V1 is determined by the following formula,

[0087]

[0088] The above equation is obtained by conversion according to the ideal gas equation. Specifically, in the to-be-measured state and the transition state, the mass of the gas in the expansion tank 200 is unchanged, and according to

[0089] PV=nRT (2).

[0090] It can be known that the ideal equation of the gas in the to-be-measured state is,

[0091] P1V1=nRT1 (3); ​​​

[0092] The ideal equation of the transition state gas is,

[0093] P2V2 = nRT2 (4);

[0094] Since the detection process mentioned in the present application is carried out in the static state of the circulating system in the operation and maintenance state, the liquid cooling medium and the gas are not heated or cooled, and the temperature of the medium and the ambient temperature change very little in a short time, therefore, in order to improve the detection accuracy and simplify the calculation process in the present application, the first temperature T1 and the second temperature T2 in the expansion tank 200 are set to be the same. Therefore, T1 = T2, and thus

[0095] P1V1 = P2V2 (5);

[0096] The conversion can obtain

[0097]

[0098] As an optional embodiment, in step S62, the first standard pressure P 1t ,

[0099]

[0100] Specifically, the first standard pressure P 1t The calculation formula is obtained by conversion through the ideal gas equation:

[0101] First, by bringing formula (6) into formula (1), we obtain

[0102]

[0103] Second, the above formula can be obtained by equation conversion,

[0104]

[0105] The above can calculate the first gas volume V1 of the gas part in the expansion tank 200 in the to-be-measured state.

[0106] Third, if it is necessary to calculate the first standard pressure P 1t of the gas part in the expansion tank 200 in the to-be-measured state, assuming that the gas in the expansion tank 200 has the same mass as the standard condition, the first standard pressure in the to-be-measured state is P 1t According to the Boyle's law,

[0107]

[0108] Fourth, the above formula (9) is converted to obtain

[0109]

[0110] The method calculates the first gas volume V1 in the to-be-measured state accurately by obtaining the first pressure P1, the second pressure P2, the first gas volume V1 and the pressure difference Vw of the expansion tank 200 in the to-be-measured state, the transition state and the standard state, and converting by the ideal gas equation, and then calculating the first standard pressure P 1t that needs to be reached in the to-be-measured state by combining the standard pressure P0, the standard volume V0 and the standard temperature T0 of the expansion tank 200 in the standard state. The calculation result is accurate and reliable, and the operation is convenient and efficient.

[0111] As an optional implementation, the pressure detection method for the expansion tank 200 of the closed circulation system in the embodiment of the present application further includes step S7, as shown in Figure 5 and Figure 7 , wherein Figure 5 is the structure diagram of the pressure detection device for the expansion tank of the closed circulation system in the transition state, as shown in Figure 4 , and Figure 7 is the flow chart of determining the pressure difference of the gas in the to-be-measured state in the pressure detection method for the expansion tank of the closed circulation system according to an embodiment of the present application. As shown in Figure 7 , step S7 includes:

[0112] S71, control the liquid supplement pipeline 401 of the expansion tank 200 to be conducted, and inject the liquid with the volume Vw into the expansion tank 200;

[0113] S72, obtain the pressure difference Pw according to the first standard pressure P 1t and the first pressure P1, wherein Pw=|P1-P 1t |; and supplement or discharge the gas in the expansion tank 200 according to the pressure difference Pw.

[0114] In the above steps, the liquid with the volume Vw is first supplemented into the expansion tank 200 to adjust the expansion tank 200 from the transition state to the to-be-measured state, at this time, the volume of the gas in the expansion tank 200 is the first gas volume V1, and the pressure of the gas is the first pressure P1. By comparing the actual first gas pressure P1 in the to-be-measured state with the first standard pressure P 1t , the difference between the first pressure P1 and the first standard pressure P 1t can be obtained. When the difference is large, the amount of gas in the expansion tank 200 needs to be adjusted.

[0115] In the above embodiment, the liquid with the volume Vw discharged in step S2 is re-injected into the expansion tank 200, and the first pressure P1 and the first standard pressure P 1tThe difference value adjusts the gas amount in the expansion tank 200, so that whether the pre-charge pressure should be adjusted and the accurate value of the pre-charge pressure adjustment can be determined accurately, and the test result is accurate and efficient.

[0116] Further, the pressure detection method for the expansion tank 200 of the closed circulation system in the embodiment of the present application further comprises a step S8, referring to Figure 5 and Figure 8 , wherein Figure 8 is the flow chart for determining the gas supplement or discharge of the expansion tank in the measured state in the pressure detection method for the expansion tank of the closed circulation system in an embodiment of the present application. As shown in Figure 8 , the step S72 comprises:

[0117] S72a, obtaining the allowable deviation ΔP of the gas pressure of the expansion tank 200;

[0118] S72b, obtaining the pressure difference Pw according to the first standard pressure P 1t and the first pressure P1, wherein Pw=|P1-P 1t |

[0119] S72c, determining whether the pressure difference Pw exceeds the allowable deviation ΔP. In the case of Pw>ΔP and P1>P 1t +ΔP, the gas discharge pipeline 504 of the expansion tank 200 is controlled to be turned on, so that the gas in the expansion tank 200 is discharged until the pressure in the expansion tank 200 reaches Pw≤ΔP; or in the case of Pw>ΔP and P1 1t -ΔP, the gas supplement pipeline 504 of the expansion tank 200 is controlled to be turned on, so that the gas is supplemented into the expansion tank 200 until the pressure in the expansion tank 200 reaches Pw≤ΔP.

[0120] The above technical solution considers the allowable deviation ΔP of the gas pressure in the expansion tank 200 in the actual measured state. When the pressure difference Pw is greater than the allowable deviation ΔP, the gas amount in the expansion tank 200 needs to be adjusted. Specifically, when P1>P 1t +ΔP, it indicates that part of the gas is inhaled in the expansion tank 200 during the operation process, and the amount of inhaled gas is greater than the allowable deviation ΔP, so that part of the gas in the expansion tank 200 needs to be released, so that the pressure difference Pw reaches the allowable deviation ΔP range. When P1 1t +ΔP, it indicates that part of the gas leaks in the expansion tank 200 during the operation process, and the amount of leaked gas is less than the allowable deviation ΔP, so that part of the gas needs to be supplemented into the expansion tank 200, so that the pressure difference Pw reaches the allowable deviation ΔP range.

[0121] The operation mode is simple, the calculation result is accurate, the gas amount in the expansion tank 200 can be kept in the standard state, and the stable operation of the closed circulation system is ensured.

[0122] As an optional embodiment, referring to Figure 9 Before the step of obtaining the first pressure P1 of the gas in the expansion tank 200 in the to-be-detected state, the method further includes:

[0123] S1.5, controlling the liquid supplement pipeline 401, the liquid discharge pipeline 101 and the gas transmission pipeline 504 of the expansion tank 200 in the to-be-detected state to be closed. The gas and the liquid in the expansion tank 200 in the to-be-detected state cannot flow, and the accuracy of the detection of the first pressure P1 in the to-be-detected state can be effectively ensured.

[0124] As an optional embodiment, the first temperature T1 of the gas in the expansion tank 200 in the to-be-detected state is obtained, including: obtaining the liquid temperature Tq flowing out of the expansion tank 200 in the to-be-detected state; obtaining the ambient temperature Tg of the environment in which the expansion tank 200 is located in the to-be-detected state; and obtaining the first temperature T1 of the gas in the expansion tank 200 in the to-be-detected state according to the calculation formula T1=(Tq+Tg) / 2. The first temperature T1 in the to-be-detected state is obtained by calculating the first temperature T1 of the gas in the expansion tank 200 by using the ambient temperature Tg and the liquid temperature Tq in the expansion tank 200, which is a method for accurately obtaining the first temperature T1 of the gas in the expansion tank 200 when the temperature detection device cannot be arranged in the expansion tank 200.

[0125] In another aspect, the embodiment of the present application provides a pressure detection device 100 for the expansion tank 200 of the closed circulation system, which is used to implement the pressure detection method in the above embodiment. Please continue to refer to Figure 4 and Figure 5 The pressure detection device 100 for the expansion tank 200 of the closed circulation system includes a liquid storage device 10 and a detection device 20. The detection device 20 includes a first temperature detection device 201, a pressure detection device 202, a flow detection device 203 and a second temperature detection device 204.

[0126] Specifically, the liquid storage device 10 comprises a liquid discharge pipeline 101, a liquid storage tank 102 and a first switch valve 103. The two ends of the liquid discharge pipeline 101 are respectively connected to the liquid inlet of the liquid storage tank 102 and the liquid connection port of the expansion tank 200, and the first switch valve 103 is arranged on the liquid discharge pipeline 101. The first temperature detection device 201 is arranged in the environment where the expansion tank 200 is located, and is used to detect the environmental temperature of the environment. The pressure detection device 202 is arranged at the gas connection port of the expansion tank 200, and is used to detect the first pressure P1 of the gas in the expansion tank 200 in the to-be-detected state and the second pressure P2 of the gas in the expansion tank 200 in the transition state. The flow detection device 203 and the second temperature detection device 204 are arranged on the liquid discharge pipeline 101 respectively. The flow detection device 203 is used to detect the volume of the liquid flowing out of the expansion tank 200, and the second temperature detection device 204 is used to detect the temperature of the liquid flowing out of the expansion tank 200 in the to-be-detected state.

[0127] The technical solution described above sets the liquid storage tank 102 to store the liquid discharged from the expansion tank 200, facilitates the change of the expansion tank 200 from the to-be-detected state to the transition state, and sets the detection device 20 to accurately measure the data of the liquid and the gas in the expansion tank 200. The measurement data obtained by the above detection method is used to determine the first standard pressure P 1t of the gas in the to-be-detected state, and then determine the accurate difference between the first pressure P1 of the gas in the expansion tank 200 and the first standard pressure P 1t , thereby avoiding the rupture of the diaphragm or the air bag in the expansion tank 200 caused by the calculation error of the difference, causing the attenuation or failure of the buffering effect, and ensuring the stable and reliable operation of the system. Moreover, the liquid in the expansion tank 200 does not need to be completely discharged, and therefore a special medium collection container is not needed, and the subsequent operation of supplementing the liquid and discharging the gas in the expansion tank 200 is omitted, thereby greatly reducing the difficulty of operation, reducing the workload of manual operation, and improving the efficiency and accuracy of detection.

[0128] As an optional implementation, the pressure detection device 100 for the expansion tank 200 of the closed circulation system further comprises a controller 30, as shown in Figure 10 The controller 30 is electrically connected to the first switch valve 103, the flow detection device 203, the first temperature detection device 201, the second temperature detection device 204 and the pressure detection device 202 respectively.

[0129] The controller 30 can control the opening or closing of the first switch valve 103, so that the liquid discharge pipeline 101 of the expansion tank 200 in the to-be-detected state is conducted or closed. At the same time, the controller 30 can also determine the first standard pressure P W of the gas in the to-be-detected state according to the first pressure P1, the second pressure P2, the first temperature T1, the volume V of the discharged liquid, the standard pressure P0, the standard volume V0 and the standard temperature T0.1t .

[0130] By setting the controller 30, the data of the expansion tank 200 in the to-be-measured state and the transition state can be automatically acquired, and the opening or closing of the first switch valve 103 can be automatically controlled, thereby reducing the labor workload, improving the efficiency and improving the detection accuracy.

[0131] As an optional implementation, the controller 30 is configured to acquire the first gas volume V1 of the gas in the to-be-measured state according to the first pressure P1, the second pressure P2 and the discharged liquid volume Vw. Moreover, the controller 30 can acquire the first standard pressure P1 of the gas in the to-be-measured state according to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0 and the standard temperature T0. 1t .

[0132] As an optional implementation, the controller 30 can determine the first gas volume V1 by the following formula:

[0133]

[0134] The above technical solution uses the controller 30 to calculate the first gas volume V1, thereby improving the calculation efficiency.

[0135] As an optional implementation, the controller 30 can also determine the first standard pressure P1 by the following formula: 1t ,

[0136]

[0137] As an optional implementation, the pressure detection device 100 for the closed circulation system expansion tank 200 further comprises a liquid supplementing device 40, and the liquid supplementing device 40 comprises a liquid supplementing pipeline 401, a liquid supplementing pump 402 and a second switch valve 403. Specifically, two ends of the liquid supplementing pipeline 401 are respectively connected to the outlet of the liquid storage tank 102 and the liquid connecting port of the expansion tank 200. The liquid supplementing pump 402 and the second switch valve 403 are arranged on the liquid supplementing pipeline 401. The controller 30 is electrically connected to the liquid supplementing pump 402 and the second switch valve 403 respectively, so as to control the second switch valve 403 to be opened, so that the liquid supplementing pipeline 401 of the expansion tank 200 is conducted, and the liquid with the volume Vw is injected into the expansion tank 200.

[0138] The liquid supplement device 40 in the above structure is provided with a liquid supplement pipeline 401 directly connecting the liquid storage tank 102 and the expansion tank 200. The second switch valve 403 is used for controlling the opening and closing of the liquid supplement pipeline 401, so as to control the supplement operation and improve the accuracy of the supplement operation. In addition, the controller 30 is electrically connected with the liquid supplement pump 402 and the second switch valve 403 respectively, and is used for automatically controlling the switching of the expansion tank 200 from the transition state to the measurement state, thereby improving the convenience of operation.

[0139] By providing the liquid supplement device 40, the discharged liquid returns to the expansion tank 200. Therefore, the liquid supplement device 40 can supplement the liquid in the expansion tank 200, keep the gas volume in the expansion tank 200 unchanged, keep the volume of the medium in the closed cycle system unchanged, and ensure the normal operation of the system. Therefore, when the medium in the expansion tank 200 is fully supplemented, the gas volume and the medium volume in the expansion tank 200 return to the measurement state. The subsequent gas supplement operation is performed in the measurement state, thereby ensuring the accuracy of the supplemented or discharged gas volume. The above structure can realize liquid supplement in a completely closed state, ensure the stable operation of the system, and improve the convenience and efficiency of operation.

[0140] As an optional embodiment, the pressure detection device 100 for the expansion tank 200 of the closed cycle system in the embodiment of the application further comprises a gas supplement device 50. The gas supplement device 50 comprises a filter 501, a gas supplement pump 502, a third switch valve 503, and a gas pipeline 504.

[0141] Specifically, the filter 501 is used for connecting a gas source. The gas source can be air or nitrogen. The filter 501 is used for filtering impurities in the gas, so as to prevent the impurities in the gas from damaging the expansion tank 200. The two ends of the gas pipeline 504 are respectively connected with the filter 501 and the gas connection port of the expansion tank 200, and are used for supplementing or discharging the gas in the expansion tank 200. The gas supplement pump 502 and the third switch valve 503 are respectively arranged in the gas pipeline 504. The gas supplement pump 502 is used for supplementing the gas in the expansion tank 200, thereby improving the efficiency of the gas supplement. The third switch valve 503 is used for controlling the opening and closing of the gas pipeline 504.

[0142] Since the liquid in the liquid storage tank 102 returns to the expansion tank 200, and the expansion tank 200 can be supplemented or discharged, the pressure detection device 100 provided by the application can be repeatedly used to detect the pre-charged pressure of the expansion tank 200. Especially when the device is applied to a wind turbine, the device can be integrated and installed on the wind turbine for online control and automatic operation at regular intervals.

[0143] The controller 30 is also electrically connected with the gas supplement pump 502 and the third switch valve 503 respectively, and is used for obtaining the allowable deviation ΔP of the expansion tank 200; according to the standard pressure P1t and the first pressure P1, to obtain a pressure difference Pw. Wherein, Pw=|P1-P 1t |; determine whether the pressure difference Pw exceeds the allowable deviation ΔP, in the case of Pw>ΔP, and P1>P 1t +ΔP, control the third switch valve 503 to open, make the gas pipeline 504 of the expansion tank 200 conductive, make the gas in the expansion tank 200 exhaust, until the pressure in the expansion tank 200 reaches Pw≤ΔP; or in the case of Pw>ΔP, and P1 1t -ΔP, control the third switch valve 503 to open and the gas supplement pump 502 to start, make the gas pipeline 504 of the expansion tank 200 conductive, supplement the gas in the expansion tank 200, until the pressure in the expansion tank 200 reaches Pw≤ΔP.

[0144] By setting the controller 30, according to the automatic control of the gas supplement and exhaust operation of the expansion tank 200, the gas control of the expansion tank 200 can be realized for 24 hours, which greatly reduces the labor intensity, improves the operation efficiency, and adjusts the gas quantity in the expansion tank according to the difference between the first pressure P1 and the first standard pressure P 1t Therefore, it can more accurately determine whether the pre-charging pressure should be adjusted and the accurate value of the pre-charging pressure adjustment, ensure the long-term stable operation of the wind turbine generator and improve the service life of the unit.

[0145] As an optional embodiment, as shown in Figure 11 The gas supplement device 50 further comprises a buffer tank 506 connected to the gas pipeline 504, the buffer tank 506 is arranged between the third switch valve 503 and the gas supplement pump 502, and the buffer tank 506 is used to buffer the fluctuation of the gas supplement pressure, to ensure the stability of the gas pressure in the gas pipeline 504 and the expansion tank 200 during gas supplement.

[0146] As an optional embodiment, the controller 30 is used to obtain the liquid temperature Tq of the expansion tank 200 in the to-be-measured state; obtain the ambient temperature Tg of the environment in which the expansion tank 200 is located in the to-be-measured state; and obtain the first temperature T1 of the gas in the expansion tank 200 in the to-be-measured state according to the calculation formula T1=(Tq+Tg) / 2. The liquid temperature Tq and the ambient temperature Tg of the expansion tank 200 are obtained by the controller 30, and the first temperature T1 is automatically calculated.

[0147] The above technical solution has two effects. On the one hand, the controller 30 can timely obtain the gas temperature change of the expansion tank 200 of the closed circulation system, to ensure the stable operation of the system. Secondly, the controller 30 can also obtain the temperature of the gas in the to-be-measured state, to provide data for the subsequent calculation of the first standard pressure.

[0148] In another aspect, the embodiments of the present application also provide a wind turbine generator, comprising a closed circulation system and the pressure detection device 100 for the expansion tank 200 of the closed circulation system according to any of the above embodiments, wherein the liquid outlet of the expansion tank 200 is provided with a fourth switch valve 104, the gas connection port of the expansion tank 200 is provided with a fifth switch valve 505, the liquid discharge pipeline 101 and the liquid inlet pipeline of the pressure detection device 100 for the expansion tank 200 of the closed circulation system are detachably connected with the fourth switch valve 104, and the gas supply pipeline 504 is detachably connected with the fifth switch valve 505. The pressure detection device 100 for the expansion tank 200 of the closed circulation system can be flexibly connected to the wind turbine generator in a detachable manner. Similarly, the above detection device can also be fixedly connected with the wind turbine generator for real-time control. The specific connection mode can be set as required, and will not be described here.

[0149] With reference to Figure 4 , Figure 5 and Figure 12 continuously, the following describes the specific working process of using the embodiments of the pressure detection device 100 for the expansion tank 200 of the closed circulation system to detect the pressure of the expansion tank 200 in the cooling circulation system (as shown in Figure 1 ) of a wind turbine generator.

[0150] As shown in Figure 1 , the closed circulation system comprises an expansion tank 200, a water pump 300, a heat source 400, a heat exchanger 500, and other necessary valves, sensors, and the like. The present application is applicable to all closed circulation systems of wind power, and the expansion tank 200 configured in the closed circulation system can be a gas bag type or a diaphragm type. The heat exchanger 500 is usually connected with the current conversion system of the electrode group, and is used for heat exchange for the current conversion system. The heat source 400 can heat or cool the medium in the system.

[0151] As shown in Figure 3 , Figure 4 and Figure 12 , the pressure detection device 100 for the expansion tank 200 of the closed circulation system comprises a liquid storage device 10, a detection device 20, a controller 30, a liquid supplementing device 40, and a gas supplementing device 50.

[0152] The liquid storage device 10 is used for storing the liquid in the expansion tank 200, the detection device 20 is used for acquiring various state data of the expansion tank 200, the liquid supplementing device 40 is used for supplementing or recovering the liquid in the expansion tank 200, and the gas supplementing device 50 is used for supplementing or recovering the gas in the expansion tank 200. The controller 30 is electrically connected with the liquid storage device 10, the detection device 20, the liquid supplementing device 40, and the gas supplementing device 50, respectively, and controls the automatic operation of the above devices.

[0153] In the embodiments of this application, the liquid storage device 10 includes a drain pipe 101, a liquid storage tank 102, and a first switching valve 103. The drain pipe 101 is connected at both ends to the inlet A of the liquid storage tank 102 and the liquid connection port B of the expansion tank 200 (typically, a fourth switching valve 104 is installed at the liquid connection port B). The first switching valve 103 is located in the drain pipe 101; specifically, the inlet and outlet of the first switching valve 103 are connected to the outlet of the flow detection device 203 and the inlet of the liquid storage tank 102, respectively. The liquid storage tank 102 has an inlet A and an outlet C. Of course, in other embodiments, the inlet and outlet of the liquid storage tank 102 can be a single liquid connection port; the above structures can achieve the technical effects of this embodiment and are not limited herein.

[0154] The detection device 20 includes a first temperature detection device 201, a pressure detection device 202, a flow detection device 203, and a second temperature detection device 204. The first temperature detection device 201 is located in the environment surrounding the expansion tank 200 and is used to detect the ambient temperature. The pressure detection device 202 is located at the gas connection port of the expansion tank 200 (typically, a third switching valve 505 is installed at this gas connection port, such as...). Figure 1 As shown, the pressure detection device 202 is connected between the third switching valve 503 and the fifth switching valve 505 at the gas connection port of the expansion tank 200, and is used to detect the first pressure P1 of the gas in the expansion tank 200 under the test state and the second pressure P2 of the gas in the expansion tank 200 under the transition state. The flow detection device 203 and the second temperature detection device 204 are respectively installed in the drain pipe 101. The flow detection device 203 is used to detect the volume of liquid flowing out of the expansion tank 200, and the second temperature detection device 204 is used to detect the temperature of the liquid flowing out of the expansion tank 200 under the test state.

[0155] The replenishment device 40 includes a replenishment pipeline 401, a replenishment pump 402, and a second switching valve 403. Specifically, the two ends of the replenishment pipeline 401 are connected to the outlet of the storage tank 102 and the liquid connection port of the expansion tank 200, respectively. The replenishment pump 402 and the second switching valve 403 are located in the replenishment pipeline 401.

[0156] The air supplement device 50 comprises a filter 501, an air supplement pump 502, a third switch valve 503 and a gas supply pipeline 504. The filter 501 is used to connect a gas source, which can be air or nitrogen. The filter 501 is used to filter impurities in the gas to prevent damage to the expansion tank 200 caused by impurities in the gas. The gas supply pipeline 504 is connected to the filter 501 and the gas connection port of the expansion tank 200 at both ends, and is used for air supplement or air release operation of the expansion tank 200. The air supplement pump 502 and the third switch valve 503 are arranged in the gas supply pipeline 504, and the air supplement pump 502 is used for air supplement operation in the expansion tank 200. The third switch valve 503 is used to control the opening or closing of the gas supply pipeline 504.

[0157] Specifically, the controller 30 is electrically connected with the first switch valve 103, the flow detection device 203, the first temperature detection device 201, the second temperature detection device 204, the pressure detection device 202, the liquid supplement pump 402, the second switch valve 403, the air supplement pump 502 and the third switch valve 503 respectively,

[0158] The controller 30 is used to control the opening or closing of the first switch valve 103 to make the liquid discharge pipeline 101 of the expansion tank 200 in the to-be-tested state conductive or closed, and control the second switch valve 403 to open to make the liquid supplement pipeline 401 of the expansion tank 200 conductive, so as to inject the liquid with a volume of Vw into the expansion tank 200. The controller 30 is also electrically connected with the first temperature detection device 201, the second temperature detection device 204, the pressure detection device 202, the liquid supplement pump 402, the second switch valve 403, the air supplement pump 502 and the third switch valve 503 respectively, so as to obtain the allowable deviation ΔP of the expansion tank 200, and determine the first standard pressure P W of the gas in the to-be-tested state according to the first pressure P1, the second pressure P2, the first temperature T1, the discharged liquid volume V 1t .

[0159] In the embodiment of the present application, the controller 30 further comprises a calculation module. After the controller 30 obtains the above data, the calculation module can determine the first gas volume V1 according to the first pressure P

[0160]

[0161] , the second pressure P2, the first temperature T1, the discharged liquid volume V

[0162]

[0163] , the standard pressure P0, the standard volume V0 and the standard temperature T0, and then determine the first standard pressure P 1t .

[0164] When the pressure detection device 100 for the expansion tank 200 of the closed cycle system is used to detect the pressure in the expansion tank 200, the following steps are included:

[0165] S1, the controller 30 acquires the standard pressure P0, the standard volume V0 and the standard temperature T0 of the gas in the expansion tank 200 in the standard state. The parameters can be input in the controller by inputting, for example. The expansion tank 200 can be a gas bag type or a diaphragm type, and the standard state can be the factory state of the expansion tank 200.

[0166] S00, the fourth switch valve 104 at the liquid connection port of the expansion tank and the valve at the gas connection port are opened.

[0167] S0, the controller 30 controls the first switch valve 103, the second switch valve 403 and the third switch valve 503 to be closed, i.e. controls the liquid supplement pipeline 401, the liquid discharge pipeline 101 and the gas pipeline 504 of the expansion tank 200 in the test state to be closed. The gas and the liquid in the expansion tank 200 in the test state cannot flow, which ensures the accuracy of the test data in the test state.

[0168] S2, the controller 30 acquires the first pressure P1 of the gas in the expansion tank 200 in the test state and calculates the first temperature T1. The above steps can include:

[0169] S21, the first pressure P1 in the test state is acquired by the pressure detection device 202 arranged at the gas connection port of the expansion tank 200.

[0170] S22, the liquid temperature Tq flowing out of the expansion tank 200 in the test state is acquired by the second temperature detection device 204, and the ambient temperature Tg of the environment in which the expansion tank 200 is located in the test state is acquired by the first temperature detection device 201. The first temperature T1 of the gas in the expansion tank 200 in the test state is acquired according to the calculation formula T1=(Tq+Tg) / 2. The temperature of the gas in the expansion tank 200 in the test state is calculated by the ambient temperature and the liquid temperature in the expansion tank 200. When the temperature detection device cannot be arranged in the expansion tank 200, the temperature of the gas in the expansion tank 200 can be accurately acquired.

[0171] It can be understood that the order of the above steps S21 and S22 can be interchanged, which is not limited herein.

[0172] S3, the controller 30 controls the first switch valve 103 to be opened, i.e. controls the liquid discharge pipeline 101 of the expansion tank 200 in the test state to be conducted.

[0173] S4, the controller 30 acquires the volume of liquid discharged from the expansion tank 200 (detected by the flow detection device 203), and when the volume of liquid discharged is Vw, the controller 30 controls the first on-off valve 103 to be closed, i.e., controls the liquid discharge pipeline 101 to be closed, and the expansion tank 200 becomes a transition state. By controlling the opening and closing of the liquid discharge pipeline 101 of the expansion tank 200, the state of the expansion tank 200 is switched from the measurement state to the transition state, and the operation is convenient.

[0174] wherein the volume of liquid discharged Vw is less than the volume of the original liquid in the expansion tank 200 in the measurement state, and in the transition state, the expansion tank 200 also stores liquid and gas, and the volume of liquid in the transition state differs by Vw, and the mass of the gas is equal to the mass of the gas in the measurement state.

[0175] S5, the second pressure P2 of the gas in the expansion tank 200 in the transition state is acquired by the pressure detection device 202;

[0176] S6, according to the first pressure P1, the second pressure P2, the first temperature T1, the volume of liquid discharged Vw, the standard pressure P0, the standard volume V0, and the standard temperature T0, the first standard pressure P of the gas in the measurement state is determined 1t The above steps can include:

[0177] S61, the first gas volume V1 of the gas in the measurement state is acquired according to the first pressure P1, the second pressure P2, and the volume of liquid discharged Vw; the first gas volume V1 is the volume of the gas in the expansion tank 200 in the measurement state. First, the volume of the gas in the measurement state is determined as the basis for calculating the pressure of the standard mass of gas in the first gas volume state. In this embodiment, the first gas volume V1 can be determined by the following formula,

[0178]

[0179] The above calculation process can be automatically calculated by the controller 30 after the controller 30 obtains the first pressure P1, the second pressure P2, and the volume of liquid discharged Vw data.

[0180] S62, the first standard pressure P of the gas in the measurement state is acquired according to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0, and the standard temperature T0 1t The first standard pressure P 1t corresponds to the mass of the gas in the standard state, and the corresponding standard pressure in the measurement state. In this embodiment, the first standard pressure P 1t ,

[0181]

[0182] After the controller 30 obtains the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0 and the standard temperature T0, the first standard pressure P 1t .

[0183] S7, calculating the gas pressure difference Pw, can include:

[0184] S71, the controller 30 controls the second switch valve 403 to open, that is, controls the liquid supplement pipeline 401 of the expansion tank 200 to be conducted, and re-injects the liquid with a volume of Vw from the liquid storage tank 102 into the expansion tank 200. After the filling is completed, the second switch valve 403 is controlled to be closed, and the liquid supplement pump 402 stops running. The gas state in the expansion tank of the liquid cooling system returns to the state to be measured. Since air does not enter the liquid cooling system during the liquid discharge process, the liquid cooling system does not need to be vented after the liquid supplement is completed;

[0185] S72, according to the standard pressure P 1t and the first pressure P1, the pressure difference Pw is obtained, wherein Pw=|P1-P 1t |; according to the pressure difference Pw, the gas in the expansion tank 200 is supplemented or discharged.

[0186] Wherein S72, the gas supplement or discharge operation of the expansion tank 200 can include

[0187] S72a, obtaining the allowable deviation ΔP of the gas pressure of the expansion tank 200;

[0188] S72b, according to the first standard pressure P 1t and the first pressure P1, the pressure difference Pw is obtained, wherein Pw=|P1-P 1t |; and

[0189] S72c, determining whether the pressure difference Pw exceeds the allowable deviation ΔP. In the case of Pw>ΔP and P1>P 1t +ΔP, the controller 30 controls the third switch valve 503 to open, that is, controls the gas supply pipeline 504 of the expansion tank 200 to be conducted, so that the gas in the expansion tank 200 is discharged, and P1 is reduced until the pressure in the expansion tank 200 reaches Pw≤ΔP; or in the case of Pw>ΔP and P1 1t -ΔP, the controller 30 controls the third switch valve 503 to open, that is, controls the gas supply pipeline 504 of the expansion tank 200 to be conducted, and controls the gas supplement pump 502 to start, to supplement the gas in the expansion tank 200, and increase P1 until the pressure in the expansion tank 200 reaches Pw≤ΔP.

[0190] In some embodiments, the above calculation process can also be performed automatically by the controller 30, improving calculation efficiency. For example, the controller 30 can continuously acquire the above data 24 hours a day and perform calculations, using the calculation results to control the automatic gas replenishment and venting operations of the expansion tank 200. By automatically controlling the implementation of the above method through the controller 30, the stable operation of the closed-loop system can be effectively guaranteed and the service life of the closed-loop system can be extended.

[0191] It should be noted that the electrical connection mentioned in this application can be understood as a line electrical connection or a communication connection, as long as it can realize the signal transmission between the controller and each device.

[0192] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for detecting pressure of a closed cycle system expansion tank, characterized by, The expansion tank stores liquid and gas in a to-be-tested state, and the pressure detection method comprises the following steps: obtaining the standard pressure P0, the standard volume V0 and the standard temperature T0 of the gas in the expansion tank in a standard state; obtaining the first pressure P1 and the first temperature T1 of the gas in the expansion tank in the to-be-tested state; controlling the liquid discharge pipeline of the expansion tank in the to-be-tested state to be open; obtaining the volume of the liquid discharged from the expansion tank, and when the volume of the liquid discharged is Vw, the liquid discharge pipeline is controlled to be closed, and the expansion tank becomes a transition state, wherein the switching from the to-be-tested state to the transition state is realized by controlling the opening and closing of the liquid discharge pipeline, and in the process, the mass of the gas in the expansion tank remains constant; obtaining the second pressure P2 of the gas in the expansion tank in the transition state; Based on the first pressure P1, the second pressure P2, the first temperature T1, and the discharged liquid volume V W The first standard pressure P of the gas under the test state is determined by the standard pressure P0, the standard volume V0, and the standard temperature T0. 1t .

2. The method for detecting pressure of a closed circulation system expansion tank according to claim 1, characterized in that, the difference Vq between the gas volumes of the to-be-tested state and the transition state in the expansion tank is equal to the volume Vw of the liquid discharged.

3. The method of claim 1, wherein, According to the first pressure P1, the second pressure P2, the first temperature T1, the discharged liquid volume V W , the standard pressure P0, the standard volume V0 and the standard temperature T0, the first standard pressure P 1t of the gas in the expansion tank under the to-be-measured state is obtained, comprising: According to the first pressure P1, the second pressure P2 and the discharged liquid volume V W Obtaining the first gas volume V1 of the gas to be measured state According to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0, and the standard temperature T0, a first standard pressure P of the gas in the to-be-tested state is obtained 1t .

4. The method for detecting pressure of a closed circulation system expansion tank according to claim 3, characterized in that, According to the first pressure P1, the second pressure P2 and the volume of the discharged liquid V W calculating a first gas volume V1 of the expansion tank in the state to be tested, comprising determining the first gas volume V1 by the formula 。 5. The method of claim 4, wherein, The first standard pressure P of the expansion tank in the state to be measured is obtained from the first gas volume V1, the standard pressure P0 and the standard gas volume V0 1t , comprising determining the first standard pressure P 1t , 。 6. The pressure detection method for a sealed circulation system expansion tank according to any one of claims 1 to 5, characterized in that, Further comprising: controlling the liquid supplement pipeline of the expansion tank to be open, and injecting the liquid with the volume Vw into the expansion tank; According to the first standard pressure P 1t and the first pressure P1, a pressure difference Pw is obtained, wherein Pw = |P1-P 1t |; according to the pressure difference Pw, supplementing or discharging the gas in the expansion tank.

7. The method of claim 6, wherein the pressure detection method for the closed cycle system expansion tank is characterized by, The step of supplementing or discharging the gas in the expansion tank according to the pressure difference Pw comprises: obtaining the allowable deviation ΔP of the expansion tank; determining whether the pressure difference Pw exceeds the allowable deviation ΔP, in the case of Pw > ΔP and P1 > P 1t + ΔP, controlling the gas pipeline of the expansion tank to be conducted, so that the gas in the expansion tank is discharged until the pressure in the expansion tank reaches Pw ≤ ΔP; or In the case of Pw > ΔP and P1 < P 1t - ΔP, the gas feed line to the expansion tank is controlled to be open and gas is fed to the expansion tank until the pressure in the expansion tank reaches Pw ≤ ΔP.

8. The method of claim 7, wherein, before the step of obtaining the first pressure P1 of the gas in the expansion tank in the to-be-tested state, further comprising: controlling the liquid supplement pipeline, the liquid discharge pipeline and the gas transmission pipeline of the expansion tank in the to-be-tested state to be closed.

9. The method of claim 8, wherein, The step of obtaining the first temperature T1 of the gas in the expansion tank in the to-be-tested state comprises: obtaining the temperature Tq of the liquid flowing out of the expansion tank in the to-be-tested state; obtaining the ambient temperature Tg of the environment in which the expansion tank is located in the to-be-tested state; according to the calculation formula T1=(Tq+Tg) / 2, obtaining the first temperature T1 of the gas in the expansion tank in the to-be-tested state.

10. A pressure detection device for a closed cycle system expansion tank, characterized by, The pressure detection device for implementing the pressure detection method of claim 1 comprises: a liquid storage device comprising a liquid discharge pipeline, a liquid storage tank and a first switch valve, wherein the two ends of the liquid discharge pipeline are respectively connected to the liquid inlet of the liquid storage tank and the liquid connection port of the expansion tank, and the first switch valve is arranged on the liquid discharge pipeline; a first temperature detection device arranged in the environment of the expansion tank, used for detecting the ambient temperature of the environment; a pressure detection device arranged at the gas connection port of the expansion tank, used for detecting the first pressure P1 of the gas in the expansion tank in the to-be-tested state and the second pressure P2 of the gas in the expansion tank in the transition state; and a flow detection device and a second temperature detection device arranged on the liquid discharge pipeline, wherein the flow detection device is used for detecting the volume of the liquid flowing out of the expansion tank, and the second temperature detection device is used for detecting the temperature of the liquid flowing out of the expansion tank in the to-be-tested state.

11. The pressure detection device for a closed cycle system expansion tank according to claim 10, characterized in that, Also included is a controller for controlling opening or closing of the first switch valve, making the drain line of the expansion tank in the state to be measured conductive or closed, and determining the first standard pressure P W of the gas in the state to be measured according to the first pressure P1, the second pressure P2, the first temperature T1, the volume V 1t of the liquid drained, the standard pressure P0, the standard volume V0, and the standard temperature T0.

12. The pressure detection device for a closed cycle system expansion tank according to claim 11, characterized in that, The controller is used for obtaining the first gas volume V1 of the gas in the to-be-tested state according to the first pressure P1, the second pressure P2 and the volume Vw of the liquid discharged; According to the first gas volume V1, the first temperature T1, the standard pressure P0, the standard gas volume V0, and the standard temperature T0, a first standard pressure P of the gas in the to-be-tested state is obtained 1t .

13. The pressure detection device for a closed cycle system expansion tank according to claim 12, characterized in that, the controller determines the first gas volume V1 by the following formula, 。 14. The pressure detection device for a closed cycle system expansion tank according to claim 13, characterized in that, The controller determines the first standard pressure P by the following equation 1t , 。 15. The pressure detection device for a closed circulation system expansion tank according to any one of claims 10 to 14, characterized in that, The pressure detection device further comprises a liquid supplementing device, the liquid supplementing device comprising a liquid supplementing pipeline, a liquid supplementing pump and a second switch valve, wherein Two ends of the liquid supplementing pipeline are connected with an outlet of the liquid storage tank and a liquid connecting port of the expansion tank respectively; The liquid supplementing pump and the second switch valve are arranged on the liquid supplementing pipeline; The controller is further configured to control the second switch valve to open, so that the liquid supplementing pipeline of the expansion tank is conducted, and liquid with a volume of Vw is injected into the expansion tank.

16. The pressure detection device for a closed cycle system expansion tank according to claim 15, characterized in that, The pressure detection device further comprises a gas supplementing device, the gas supplementing device comprising a filter, a gas supplementing pump, a third switch valve and a gas pipeline, the filter being configured to be connected with a gas source, two ends of the gas pipeline being connected with the filter and a gas connecting port of the expansion tank respectively, the gas supplementing pump and the third switch valve being arranged on the gas pipeline respectively; The controller is further configured to obtain the allowable deviation ΔP of the expansion tank; According to the first standard pressure P 1t and the first pressure P1, a pressure difference Pw is obtained, wherein Pw = |P1-P 1t |; determining whether the pressure difference Pw exceeds the allowable deviation ΔP, in the case of Pw > ΔP and P1 > P 1t + ΔP, controlling the third switch valve to open, making the gas pipeline of the expansion tank conductive, making the gas in the expansion tank exhaust until the pressure in the expansion tank reaches Pw ≤ ΔP; or In the case of Pw > ΔP and P1 < P 1t In the case of Pw > ΔP and P1 ΔP and P1 < P 17. The pressure detection apparatus for a closed cycle system expansion tank according to claim 16, wherein The controller is configured to obtain a liquid temperature Tq of the expansion tank in the to-be-tested state, obtain an ambient temperature Tg of an environment in which the expansion tank is located in the to-be-tested state, and obtain a first temperature T1 of gas in the expansion tank in the to-be-tested state according to a calculation formula T1=(Tq+Tg) / 2.

18. The pressure detection apparatus for a sealed circulation system expansion tank according to claim 16, characterized by, The gas supplementing device further comprises a buffer tank connected with the gas pipeline, the buffer tank being arranged between the third switch valve and the gas supplementing pump.

19. A wind power unit, characterized in that The pressure detection device for an expansion tank of a closed circulation system, as claimed in any one of claims 10 to 18, wherein a fourth switch valve is arranged at a liquid outlet of the expansion tank, a fifth switch valve is arranged at a gas connecting port of the expansion tank, a liquid discharging pipeline and a liquid inletting pipeline of the pressure detection device are detachably connected with the fourth switch valve, and a gas pipeline of a gas supplementing device of the pressure detection device is detachably connected with the fifth switch valve.

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