Converter system, converter power module health status assessment method and device

Abstract

The present invention discloses a method and device for evaluating the health status of a converter system and a converter power module. The converter system includes: at least one power module, a cooling branch and a heat metering module corresponding to the power module, and a cooling circulation main circuit; wherein the cooling branch is connected in parallel to the cooling circulation main circuit, and the coolant in each cooling branch is used to absorb the heat loss generated by the operation of the corresponding power module; the heat metering module is arranged at the port of the corresponding cooling branch, and is used to measure the heat loss absorbed by the coolant when it flows through the corresponding cooling branch. The embodiment of the present invention can accurately evaluate the health status of the converter power module.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a method and device for evaluating the health status of a converter system and a converter power module. Background Art

[0002] The converter of a wind turbine generator set is composed of power modules in parallel, each of which includes one or more IGBT (Insulated Gate Bipolar Transistor) modules, which are power semiconductor devices. The power modules will gradually age (i.e., their health status will deteriorate) during use. When the power modules are running in a poor health state, the reliability of the converter operation will be reduced. Currently, there is no evaluation method for the health status of the converter power modules. Summary of the invention

[0003] The embodiments of the present invention provide a converter system, a method and a device for evaluating the health status of a converter power module, which can accurately evaluate the health status of the converter power module.

[0004] In a first aspect, an embodiment of the present invention provides a converter system, which includes: at least one power module, a cooling branch and a heat metering module arranged corresponding to the power module, and a cooling circulation main circuit; wherein the cooling branch is connected in parallel to the cooling circulation main circuit, and the coolant in each cooling branch is used to absorb the heat loss generated by the operation of the corresponding power module; the heat metering module is arranged at the port of the corresponding cooling branch, and is used to measure the heat loss absorbed by the coolant when flowing through the corresponding cooling branch.

[0005] In a second aspect, an embodiment of the present invention provides a method for evaluating the health status of a converter power module, which is used to evaluate the health status of the power modules in the above-mentioned converter system, and is characterized in that the method includes: obtaining the operating status parameters of the wind turbine to be tested, and the heat loss measurement values ​​of each power module in the converter system of the wind turbine to be tested; determining the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine according to the operating status parameters of the wind turbine to be tested; determining the health status of each power module in the converter system of the wind turbine to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine.

[0006] In a third aspect, an embodiment of the present invention provides a health status assessment device for a converter power module, which is used to assess the health status of the power modules in the above-mentioned converter system, and is characterized in that the device comprises: an acquisition module, which is used to acquire the operating status parameters of the wind turbine to be tested, and the heat loss measurement values ​​of each power module in the converter system of the wind turbine to be tested; a first determination module, which is used to determine the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine according to the operating status parameters of the wind turbine to be tested; and a second determination module, which is used to determine the health status of each power module in the converter system of the wind turbine to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine.

[0007] In a fourth aspect, an embodiment of the present invention provides a wind turbine generator set, which includes: a health status assessment device for a converter power module as described above.

[0008] In a fifth aspect, an embodiment of the present invention provides a system comprising at least one computing device and at least one storage device storing instructions, characterized in that when the instructions are executed by the at least one computing device, they prompt the at least one computing device to execute the health status assessment method of the converter power module.

[0009] In a sixth aspect, an embodiment of the present invention provides a computer-readable storage medium storing instructions, characterized in that when the instructions are executed by at least one computing device, the at least one computing device is prompted to execute the health status assessment method of the converter power module.

[0010] In the embodiment of the present invention, the converter of the wind turbine generator set to be tested can be understood as an old converter that has been running for a period of time, and the converter of the reference wind turbine generator set can be understood as a new converter. The old converter is used as the converter to be tested, and the new converter is used as the reference converter. The wind turbine generator sets corresponding to the new and old converters are operated under the same operating state parameters. In this way, the heat loss value of the power module of the new converter can be used as a reference standard for the heat loss value of the power module of the old converter. Since the heat loss amount generated by the operation of the power module is closely related to the aging state of its bonding wire, the more serious the aging of the bonding wire, the higher the heat loss amount generated by the operation of the power module, the worse the health state of the power module, and the greater the difference between the heat loss measurement value of the power module and the heat loss reference value of the corresponding power module. Therefore, according to the difference between the heat loss measurement value of each power module of the converter system of the wind turbine generator set to be tested and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set, the health state of each power module in the converter system of the wind turbine generator set to be tested can be determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic diagram of a fluctuation curve of the output power of a wind turbine generator set according to an embodiment of the present invention as a function of the ambient wind speed;

[0012] Figure 2 A schematic diagram of a fluctuation curve of the ambient wind speed and ambient temperature of a wind turbine generator set provided according to an embodiment of the present invention;

[0013] Figure 3 A schematic diagram of the layer structure of an IGBT module provided according to an embodiment of the present invention and the thermal expansion coefficient corresponding to each layer material;

[0014] Figure 4 A force analysis diagram of a bonding wire provided according to an embodiment of the present invention;

[0015] Figure 5 A schematic diagram of a bond wire breakage according to an embodiment of the present invention;

[0016] Figure 6 A schematic diagram of a bonding wire falling off according to an embodiment of the present invention;

[0017] Figure 7 A schematic diagram of the internal structure of an IGBT module provided according to an embodiment of the present invention;

[0018] Figure 8 A schematic diagram of the internal layout of an IGBT module provided according to an embodiment of the present invention;

[0019] Fig. 9 An equivalent circuit diagram of an IGBT module provided according to an embodiment of the present invention;

[0020] Fig.10 A graph showing the variation of heat loss of an IGBT module with gate resistance according to an embodiment of the present invention;

[0021] Fig.11 A schematic diagram of the structure of the centralized cooling of the IGBT module provided according to an embodiment of the present invention;

[0022] Fig.12 A schematic diagram of the structure of independent cooling of an IGBT module provided according to an embodiment of the present invention;

[0023] Fig.13 A schematic diagram of a converter cooling structure provided according to an embodiment of the present invention;

[0024] Fig.14 A schematic diagram of heat transfer inside an IGBT module provided according to an embodiment of the present invention;

[0025] Fig.15 A schematic diagram of the structure of a converter system provided according to an embodiment of the present invention;

[0026] Fig.16 A schematic diagram of sensor wiring provided according to an embodiment of the present invention;

[0027] Fig.17 A schematic diagram of sensor installation according to an embodiment of the present invention;

[0028] Fig.18 A schematic diagram of a measurement structure for centralized cooling of an IGBT module according to an embodiment of the present invention;

[0029] Fig.19 A schematic diagram of a measurement structure for independent cooling of an IGBT module according to an embodiment of the present invention;

[0030] Fig. 20 A schematic diagram of a flow chart of a method for evaluating the health status of a power module of a converter provided according to an embodiment of the present invention;

[0031] Fig.21 It is a schematic diagram of the structure of a health status assessment device for a converter power module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The features and exemplary embodiments of various aspects of the present invention will be described in detail below.In the following detailed description, numerous specific details are set forth in order to provide a comprehensive understanding of the present invention.

[0033] The converter of wind turbine generator sets needs to operate for a long time under frequent and wide range of random output conditions. Figure 1 The output power of wind turbine generator set fluctuates with the ambient wind speed. Figure 1 It can be seen that with the random changes in the ambient wind speed (Windspeed), the output power (Output power) of the wind turbine generator set fluctuates cyclically, where the minimum output power is about 0.4pu and the maximum output power is about 1p.u, which makes the converter one of the devices most prone to failure in the entire wind power system.

[0034] In addition, wind farms are generally located in places with harsh climatic conditions such as mountainous areas and seas, which puts wind turbines in high altitude, high temperature, humidity, dust and other environments, further reducing the reliability and service life of wind turbine converters. Figure 2 The fluctuation curves of the ambient wind speed and ambient temperature of the wind turbine generator set are shown. Figure 2 It can be seen that the fluctuation range of the ambient wind speed (Wind speed) in which the wind turbine generator set is located reaches 0 to 28 m / s, and the fluctuation range of the ambient temperature (Ambitent Temp.) in which the wind turbine generator set is located reaches -2.5 to 18°C.

[0035] The inverter of a wind turbine generator set is constructed by connecting power modules in parallel. Each power module includes one or more power semiconductor device IGBT (Insulated Gate Bipolar Transistor) modules. The IGBT module is the core component of the inverter and also one of the weakest components in the inverter. The performance of the IGBT module determines the normal and reliable operation of the wind turbine generator set.

[0036] Figure 3 The layer structure of the IGBT module and the corresponding thermal expansion coefficient of each layer material are shown. Figure 3 It can be seen that the top layer of the IGBT module is the silicon chip, which includes the IGBT chip and the diode chip. The IGBT chip and the diode chip are connected by aluminum bonding wires, and the silicon chip and the solder layer are also connected by aluminum bonding wires. The thermal expansion coefficients of the silicon chip and the aluminum bonding wire are 3×10 -6 / ℃ and 22×10 -6 / ℃.

[0037] As the ambient wind speed changes randomly, the output power of the wind turbine and the loss of the converter also change accordingly, causing the junction temperature of the IGBT module to fluctuate randomly. Under the influence of the temperature fluctuation inside the IGBT module, the alternating thermal stress caused by the mismatch of the thermal expansion coefficients of the interlayer materials causes fatigue damage inside the IGBT module. Figure 4 Due to the large difference in thermal expansion coefficients between silicon chips and aluminum bonding wires, cracks are easily generated at the contact point between the two under the action of alternating thermal stress, which eventually causes the aluminum bonding wire to fall off or break. Figure 5 , some bonding wires in area 501 and area 502 are detached, and see Figure 6 , some bonding wires in the 601 area are broken. According to the fatigue cumulative damage principle, as the IGBT module runs longer, its internal defects will become more and more serious, and its health level will become lower and lower. When the power module runs in a poor health state, the reliability of the converter operation will be reduced, and eventually the converter power module will age and fail.

[0038] Figure 7 The internal structure of the IGBT module is shown in Figure 8 The internal layout of the IGBT module is shown in Figure 7 and Figure 8It can be seen that there are multiple bonding wires connected in parallel inside the IGBT module, which are used to realize the electrical connection between the IGBT chip and the diode chip FWD, and between the internal chip and the external circuit. Since the bonding wires are very easy to fall off during the power thermal cycle, which will deteriorate the working state of the chip, the bonding wires have become one of the main research objects of IGBT module failure.

[0039] The study found that with the long-term operation of wind turbines, the converter has been in a power circulation state under the influence of wind characteristics. The junction temperature fluctuation amplitude of its core component IGBT module is large. Coupled with the influence of ambient temperature fluctuations, the internal part of the IGBT module is easily damaged, resulting in changes in the electrothermal parameters of the IGBT module.

[0040] See also Fig. 9 The IGBT module equivalent circuit diagram, and Fig.10 The IGBT module heat loss E varies with the gate resistance R G The change diagram of the IGBT module heat loss E includes the opening energy consumption E on and shutdown energy consumption E off When a bond wire fails and falls off, the current carried by other bond wires will increase, the electrothermal stress they bear will also increase successively, and the parasitic parameters will change, which is mainly manifested in the change of bond wire equivalent resistance and on-state resistance. Therefore, the breakage of the bond wire will accelerate the aging and failure of the power module. Studies have shown that during the aging process of the IGBT module, the saturation voltage drop, gate voltage, and turn-on energy consumption E of the IGBT module are compared with the experimental measurement values ​​in the module data sheet. on , Shutdown energy consumption E off , conduction energy consumption and thermal resistance are all increased compared with the initial values. on and shutdown energy consumption E off The increase is large.

[0041] Therefore, the health of the converter can be evaluated by monitoring the changes in the characteristic quantities of the converter IGBT module, and problems can be discovered in a timely manner. Corresponding measures can be taken to minimize losses and improve the reliability of the converter system.

[0042] In some embodiments, the relationship between online monitoring data such as junction temperature, shell temperature, saturation voltage drop, equivalent thermal resistance, ripple current, etc. of the IGBT module and the device characteristic quantity can be collected by external equipment to determine the health status of the IGBT module. However, due to the alternating electrothermal stress caused by the randomness of the wind and the change of the operating conditions, the electrothermal parameters of the IGBT module have changed, and the monitoring results of the health status of the IGBT module based on the initial operating characteristics are not accurate enough. In addition, many characteristic parameter states are mostly in the nanosecond level, with small changes, and are easily interfered by external factors. It is difficult to accurately measure the health status of the IGBT module, and the measurement hardware circuit requirements are very high. In addition, the packaging of the field converter module cannot be easily disassembled, or is blocked by other devices, and it is very difficult to install external equipment to the corresponding position in the converter.

[0043] In some embodiments, it is also possible to install peripheral detection equipment, such as sensors, detection circuits, and signal lines, on some low-power IGBT modules based on the laboratory. In the set ambient temperature (in the incubator), the host computer issues a work instruction to the IGBT module to be tested, and the detection equipment collects characteristic quantity data, and then analyzes the data for aging evaluation. However, these methods require high-precision detection instruments and a large number of signal lines connected to the IGBT module, which are only suitable for laboratories with good environment and sufficient conditions. The wind turbine converter is installed in the tower or cabin, where the environmental conditions are poor and the remaining space is small, which is not convenient for building such a detection platform. In addition, the IGBT module wiring of the converter is dense, and there is almost no space for installing detection instruments and wiring, which is difficult to implement. If additional detection equipment and connection lines are installed, the EMC of the converter may be affected, and electromagnetic interference may be generated between each other, making the data collected by the detection equipment inaccurate, not only failing to evaluate the internal aging degree of the IGBT module well, but the detection equipment may also affect the normal operation of the converter. Moreover, the above detection methods set the failure threshold value under specific conditions to test the IGBT module, which is greatly affected by the environment and the aging process of the IGBT module and cannot well reflect the internal defect status of the IGBT module. In addition, these detection methods require high-precision testing equipment and professional testing personnel, and have high requirements for technical personnel. The reliability evaluation system needs to be further improved, and the operation is too complicated and difficult, which is not suitable for engineering applications and difficult to be applied on a large scale to the health status detection of wind power converters.

[0044] According to the experience of wind turbine maintenance, wind farms are located in remote and faraway mountainous areas, Gobi Desert or at sea, with various conditions limited, and the maintenance of the units is inconvenient and costly. Once the IGBT module fails, it will cause serious economic losses and even cause major safety accidents. Therefore, it is very important to ensure the reliability of the IGBT module during operation and effectively evaluate the health status of the IGBT module. Therefore, wind farms are in urgent need of a simple and feasible method for on-site detection of IGBT modules.

[0045] At present, in order to meet the requirements of standardization, versatility, scalability and short development cycle, the structural design of large wind turbine converters adopts the power module parallel connection method. Both the grid-side converter and the machine-side converter are composed of multiple power modules in parallel, and each power module is composed of multiple IGBT modules. IGBT modules generate heat during operation, and the cooling of IGBT modules can be divided into two methods: centralized cooling and independent cooling.

[0046] See also Fig.11 Centralized cooling is performed for multiple IGBT modules of the same power module installed on a water-cooled plate (radiator) 111, and the water-cooled plate 111 is fixed on a back plate 112, that is, multiple IGBT modules share one water-cooled plate 111 for cooling, and each water-cooled plate 111 has a liquid inlet 1111 and a liquid outlet 1112.

[0047] See also Fig.12 , each IGBT module of the power module is independently cooled and mounted on its own water cooling plate 111 , and multiple water cooling plates 111 are fixed on the same back plate 112 , that is, each IGBT module is independently cooled using a water cooling plate 111 . Fig.12 The figure also shows the appearance of an independently cooled IGBT module.

[0048] Fig.13 The 11 power modules of the converter system are shown, among which power modules M1, M2, M6, and M7 form the machine-side power module, power modules M3-M5 and M8-M10 form the grid-side power module, and power module M11 forms the brake power module. Each power module corresponds to a cooling branch 131, and all cooling branches 131 are connected in parallel to the cooling cycle main circuit 132. The heat generated by the IGBT module in the power module is first transferred to the water-cooled plate radiator by heat conduction (see Fig.14 ), the water-cooled plate radiator transfers the heat to the coolant by convection, the coolant carries the heat through the pipeline and transfers it to the external radiator, and finally dissipates it into the environment.

[0049] If the bonding wire of the IGBT module in the power module is broken, the loss of the IGBT module will increase, which will increase the heat absorbed by the liquid in the cooling branch where the power module is located. By comparing the heat absorbed by the coolant of the normal power module, the power module with increased heat loss can be analyzed. Therefore, when the switching frequency, output current, ambient temperature and drive system remain unchanged, the heat loss change characteristics can be used as an important basis for monitoring the state of the bonding wire.

[0050] Based on this, an embodiment of the present invention provides a converter system, see Fig.15 The converter system includes: at least one power module, a cooling branch 131 and a heat metering module 150 arranged corresponding to the power module, and a cooling circulation main circuit 132; wherein the cooling branch 131 is connected in parallel to the cooling circulation main circuit 132, and the coolant in each cooling branch 131 is used to absorb the heat loss generated by the operation of the corresponding power module; the heat metering module 150 is arranged at the port of the corresponding cooling branch 131, and is used to measure the heat loss absorbed by the coolant when flowing through the corresponding cooling branch 131.

[0051] In the converter system in the embodiment of the present invention, the coolant in each cooling branch 131 can absorb the heat loss generated by the operation of the corresponding power module. Since the heat loss generated by the operation of the power module is closely related to the aging state of its bonding wires, the more serious the aging of the bonding wires, the higher the heat loss generated by the operation of the power module, that is, the worse the health state of the power module. Therefore, by using the heat metering module 150 to measure the heat loss absorbed by the coolant when flowing through the corresponding cooling branch 131, the health state of the power module in the converter system can be obtained.

[0052] That is to say, when measuring the heat loss of the power module, the embodiment of the present invention uses the coolant as the heat conduction medium, and uses the heat absorbed by the coolant flowing through the power module to characterize the heat loss of the power module. In this way, there is no need to introduce complex external circuits into the converter, such as wiring and installing sensors on the power module, so as not to damage the internal EMC environment of the converter, generate electromagnetic interference, affect the working circuit of the power module, or affect the normal operation of the module. The hardware system is simple, accurate and reliable. In addition, no professional testing instruments are required, and the operation is simple. Ordinary technicians on site can complete the detection, which is not restricted by the environment and conditions of the converter. The aging process of the IGBT module in the converter and its health status evaluation can be performed anytime and anywhere, thereby optimizing and guiding the inspection and maintenance of the wind power converter.

[0053] Specifically, the heat loss of the coolant flowing through each cooling branch can be determined by the flow rate of the coolant at the inlet, the temperature at the inlet, the flow rate at the outlet, and the temperature at the outlet in each cooling branch. Correspondingly, the heat metering module may include: an inlet flow rate sensor, an inlet temperature sensor, an outlet flow rate sensor, and an outlet temperature sensor, wherein the inlet flow rate sensor may be placed at the inlet of each cooling branch to measure the flow rate of the coolant at the inlet in each cooling branch; the inlet temperature sensor may be set at the inlet of each cooling branch to measure the temperature of the coolant at the inlet in each cooling branch; the outlet flow rate sensor may be set at the outlet of each cooling branch to measure the flow rate of the coolant at the outlet in each cooling branch; the outlet temperature sensor may be set at the outlet of each cooling branch to measure the temperature of the coolant at the outlet in each cooling branch.

[0054] See also Fig.16 The inlet flow rate sensor, the inlet temperature sensor, the outlet flow rate sensor and the outlet temperature sensor can be installed on the water pipe of the cooling branch corresponding to each power module. The signal line 161 of each sensor can be connected to the measurement host 162. The host 162 can calculate the heat loss of each cooling branch according to parameters such as pipe diameter, flow rate and temperature, and store the data locally, or upload the data remotely. The host 162 can also have multiple channels to measure the heat loss of multiple cooling branches at the same time.

[0055] For example, the flow rate sensor can be installed on a measuring joint similar to a tee. The flow rate sensor can be a non-contact type, such as an ultrasonic flow rate sensor. Fig.17 The ultrasonic flow velocity sensor 172 can be closely attached to the water pipe wall of the cooling branch, and then a coupling agent is applied between the ultrasonic flow velocity sensor 172 and the pipe wall, and the ultrasonic flow velocity sensor 172 is fixed to the measuring joint 171 using a clamp 173. The flow velocity sensor can also be a contact type, which is similar to the temperature sensor 174 and can be installed inside the measuring joint 171 to perform measurements by contacting the coolant.

[0056] In specific implementation, the inlet and outlet water pipes of the power module can be disassembled first, and then the measuring connector 171 equipped with the above-mentioned sensor can be installed in series in the inlet and outlet pipes of the cooling branch 131, and finally the sensor signal line 161 can be connected to the host 162.

[0057] See also Fig.18 In the three power modules (M1, M2 and M3), each power module includes a plurality of IGBT modules. The IGBT modules in each power module are centrally cooled. When in use, two sets of measuring joints can be installed at the liquid inlet and liquid outlet of the cooling branch 131 corresponding to each power module. Fig.18 The installation positions of the liquid outlet sensor and the liquid inlet sensor under the independent cooling mode are shown (see the dotted box).

[0058] See also Fig.19 In the three power modules (M1, M2 and M3), each power module includes an IGBT module. One IGBT module in each power module is cooled independently. When in use, two sets of measuring joints can be installed at the liquid inlet and liquid outlet of the cooling branch corresponding to each IGBT module. Fig.19 The installation positions of the liquid outlet sensor and the liquid inlet sensor in the independent cooling mode are also shown.

[0059] The embodiment of the present invention also provides a method for evaluating the health status of a power module of a converter, which is used to evaluate the health status of a power module in the converter system described above. Fig. 20 ,The health status assessment method of the converter power module includes:

[0060] Step 201 : obtaining the operating state parameters of the wind turbine generator set to be tested and the heat loss measurement values ​​of each power module in the converter system of the wind turbine generator set to be tested.

[0061] Step 202: Determine the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating status parameters of the wind turbine generator set to be tested.

[0062] Specifically, a reference wind turbine generator set having the same equipment parameters as the wind turbine generator set to be tested can be first determined, and then the heat loss measurement value of the corresponding power module in the converter system of the reference wind turbine generator set when the reference wind turbine generator set is operating under the operating state parameters of the wind turbine generator set to be tested can be determined as the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set. Here, the equipment parameters being completely identical can be understood as the model and production batch of the wind turbine generator set to be tested and the reference wind turbine generator set being the same, and correspondingly, the composition structure and operating parameters of the wind turbine generator set to be tested and the reference wind turbine generator set are also the same.

[0063] Step 203 , determining the health status of each power module in the converter system of the wind turbine generator set to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set.

[0064] The converter of the wind turbine generator set to be tested can be understood as an old converter that has been running for a period of time, and the converter of the reference wind turbine generator set can be understood as a new converter.

[0065] In the embodiment of the present invention, the old converter is used as the converter to be tested, the new converter is used as the reference converter, and the wind turbine generator sets corresponding to the new and old converters are operated under the same operating state parameters, so that the heat loss value of the power module of the new converter can be used as a reference standard for the heat loss value of the power module of the old converter. Since the heat loss amount generated by the operation of the power module is closely related to the aging state of its bonding wires, the more serious the aging of the bonding wires, the higher the heat loss amount generated by the operation of the power module, the worse the health state of the power module, and the greater the difference between the heat loss measurement value of the power module and the heat loss reference value of the corresponding power module. Therefore, according to the difference between the heat loss measurement value of each power module of the converter system of the wind turbine generator set to be tested and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set, the health state of each power module in the converter system of the wind turbine generator set to be tested can be determined.

[0066] Specifically, the error interval of the difference between the heat loss measurement value of each power module in the wind turbine converter system to be tested and the heat loss reference value of each corresponding power module in the reference wind turbine converter system can be determined first; then, based on the correspondence between the preset error interval and the health level, the health status level corresponding to each difference is determined; finally, based on the health status level corresponding to each difference, the health status of each power module in the wind turbine converter system to be tested is determined.

[0067] In some embodiments, the maintenance level corresponding to each difference may be determined based on the correspondence between the preset error interval and the maintenance level; and the maintenance operation of each power module in the converter system of the wind turbine generator set to be tested may be determined based on the maintenance level corresponding to each difference.

[0068] For example, using E t Represents the measured value of heat loss, E r represents the heat loss reference value, then the difference between the heat loss measurement value and the corresponding heat loss reference value △E is equal to E t -E r When 0<△E<n, the power module corresponding to △E is evaluated as slightly aged, and it is recommended that the converter be derated for a period of time; when m<△E<l, the power module corresponding to △E is evaluated as severely aged, and it is recommended that the converter immediately replace the module or modules. Among them, the range of the error interval, that is, the values ​​of n, m, and l can be determined through comprehensive research on IGBT module bonding wire failure analysis and engineering experience, and is not limited here.

[0069] In some embodiments, the heat absorbed by the coolant in the cooling branch corresponding to each power module in the converter system of the wind turbine generator set to be tested can be determined as the heat loss measurement value of the power module. That is to say, when measuring the heat loss of the power module, the embodiment of the present invention uses the coolant as the heat conduction medium, and uses the heat absorbed by the coolant flowing through the power module to characterize the heat loss of the power module. In this way, there is no need to introduce complex external circuits in the converter, such as wiring and installing sensors on the power module, so as not to damage the internal EMC environment of the converter, not to generate electromagnetic interference, not to affect the working circuit of the power module, and not to affect the normal operation of the module. The hardware system is simple, accurate and reliable. In addition, no professional testing instruments are required, the operation is simple, and ordinary technicians on site can complete the detection. It is not restricted by the environment and conditions of the converter. The aging process of the IGBT module in the converter and its health status evaluation can be performed anytime and anywhere, thereby optimizing and guiding the inspection and maintenance of the wind power converter.

[0070] Specifically, when the wind turbine generator set to be tested is operating under the operating state parameters, the temperature of the coolant at the liquid inlet, the flow rate at the liquid inlet, the temperature at the liquid outlet and the flow rate at the liquid outlet in the cooling branch corresponding to each power module of the converter system of the wind turbine generator set to be tested are obtained; according to the temperature of the coolant at the liquid inlet and the flow rate at the liquid inlet in the cooling branch corresponding to each power module, the heat of the coolant at the liquid inlet in the cooling branch corresponding to each power module is calculated; according to the temperature of the coolant at the liquid outlet and the flow rate at the liquid outlet in the cooling branch corresponding to each power module, the heat of the coolant at the liquid outlet in the cooling branch corresponding to each power module is calculated; the difference between the heat of the coolant at the liquid outlet and the heat at the liquid inlet in the cooling branch corresponding to each power module is calculated to obtain the heat absorbed by the coolant in the cooling branch corresponding to each power module.

[0071] The following is an explanation of the process of selecting the operating status parameters of the wind turbine generator set.

[0072] Considering that the heat loss measurement value of the power module is easily affected by changes in ambient wind speed, the operating status parameters may include the ambient wind speed. Random changes in ambient wind speed will cause random changes in the power of the wind turbine generator set. Therefore, the operating status parameters may also include power mode and power.

[0073] Exemplarily, when evaluating the health status of the power module in the converter system of the wind turbine to be tested, the ambient wind speed can be limited to no less than the rated wind speed, and the power mode is a limited power mode, that is, the wind turbine to be tested and the reference wind turbine are operated at limited power under conditions greater than the rated wind speed, and the heat loss values ​​of their respective converters are measured under different power conditions. With such a setting, the converter is always in a constant power state during the detection process, and there is no thermal cycle phenomenon, which cannot avoid the impact of power fluctuations caused by the randomness of the wind on the evaluation results of the health status of the power module.

[0074] If a power module has a large number of broken IGBT module bonding wires, the heat loss value of this power module at low power will be greater than the heat loss value of other normal power modules, and the heat loss value at high power or full power will be much greater than the heat loss value of normal power modules. In other words, as the power increases, the difference in heat loss value between the power module to be tested and the normal power module will be more obvious. Therefore, the operating state parameter can also include a power value in a preset power set, and the preset power set includes multiple power values, which can be in an arithmetic progression.

[0075] Exemplarily, the heat loss value of the power module at one power value can be measured each time, and the heat loss values ​​of the power module at multiple power values ​​can be obtained by multiple measurements. By subtracting the heat loss values ​​of the power module to be tested and the reference power module at multiple power values, the degree of aging of the bonding wires of the IGBT module at different power values ​​can be analyzed, thereby improving the accuracy of the power module health status assessment results.

[0076] When using the heat absorbed by the coolant in the cooling branch to characterize the heat loss measurement value corresponding to the power module, considering the impact of ambient temperature on the cooling process, the operating status parameter can also include a temperature value in a preset ambient temperature set, and the preset temperature set includes multiple temperature values, which can be in an arithmetic progression.

[0077] For example, the heat loss value of the temperature module at one temperature value can be measured each time, and the heat loss value of the temperature module at multiple temperature values ​​can be obtained by multiple measurements. By subtracting the heat loss values ​​of the temperature module to be measured and the reference temperature module at multiple temperature values, the aging degree of the bonding wires of the IGBT module at different temperature values ​​can be analyzed, thereby more comprehensively reflecting the health status of the power module.

[0078] It should be noted that the operating status parameters of the wind turbine generator set may include one or more of the ambient wind speed, power mode, power value and temperature value, which are not limited here. For ease of understanding, the following takes a 3.0MW unit as an example to illustrate the health status assessment method of the power module in the converter system of the embodiment of the present invention.

[0079] First, under the constant power operation state of the converter and the same ambient temperature, the heat loss value of each power module in the wind turbine to be tested and the reference wind turbine is measured. The unit power is set once for each measurement. The time interval between each measurement is T (for example, 20 minutes). The measurement starts from 500kw. After each measurement, the power value increases by △P, that is, the step size is △P (for example, 500kw). The measurement is performed six times in a row, and the heat loss values ​​measured for each power module are summarized.

[0080] Then, the loss data of the inverter under test is compared with the data of the reference inverter. According to the difference between the heat loss value of a power module of the inverter under test and the heat loss value of the corresponding power module of the reference inverter, the aging degree of the IGBT module bonding wire of this power module, that is, the health status of this power module, is determined.

[0081] The above method can be understood as a manual detection of the converter power module. As large wind turbines are becoming more intelligent, the health status of the converter power module can also be identified by the converter control system, that is, the heat loss calculation, comparative analysis and fault judgment functions of the converter power module in the converter control strategy, that is, the automatic detection of the health status of the converter power module. During automatic detection, the coolant temperature sensor and flow rate sensor signal lines can be connected to the converter control system. The converter controller (such as PLC) collects temperature data and flow rate data in real time, calculates the heat loss increase △E of the power module under each power condition, reads the heat loss reference value, and judges whether the converter power module is normal or reports a corresponding fault according to the set fault value (trigger condition).

[0082] In specific implementation, a matrix table (see Table 1) can be designed according to the analysis needs to record the heat loss value of each power module measured each time, and then a comprehensive analysis can be performed using big data, statistics, disassembly of damaged modules, and engineering tests. This can directly identify the aging degree of the IGBT module in the power module and the health status of the power module, and can predict the life of the power module based on the increasing trend of heat loss.

[0083] Table 1

[0084]

[0085] The first row in Table 1 is the power value (expressed as Pr), the first column is the ambient temperature value (expressed as Ta), E r1 , K 1 , △E 1 It indicates the heat loss reference value, trigger condition (such as error threshold), and heat loss increase △E of power module No. 1 when the power value is 1000kw and the ambient temperature value is 10℃.

[0086] In addition, if there is a problem with the drive system (drive board) of the converter IGBT module, it may also cause an increase in the heat loss of the IGBT module. Therefore, before obtaining the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested, it is also possible to first determine whether the drive board of the converter system of the wind turbine generator set to be tested is faulty; if the drive board of the converter system of the wind turbine generator set to be tested is normal, then obtain the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested, so as to improve the accuracy of the health status assessment of the converter power module.

[0087] The embodiment of the present invention further provides a device for evaluating the health status of a power module of a converter, which is used to evaluate the health status of a power module in the above converter system. Fig.21 , the health status assessment device of the converter power module comprises:

[0088] The acquisition module 211 is used to acquire the operating state parameters of the wind turbine generator set to be tested and the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested;

[0089] A first determination module 212 is used to determine the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating state parameters of the wind turbine generator set to be tested;

[0090] The second determination module 213 is used to determine the health status of each power module in the converter system of the wind turbine to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the reference wind turbine converter system.

[0091] In the embodiment of the present invention, the converter of the wind turbine generator set to be tested can be understood as an old converter that has been running for a period of time, and the converter of the reference wind turbine generator set can be understood as a new converter. The old converter is used as the converter to be tested, and the new converter is used as the reference converter. The wind turbine generator sets corresponding to the new and old converters are operated under the same operating state parameters. In this way, the heat loss value of the power module of the new converter can be used as a reference standard for the heat loss value of the power module of the old converter. Since the heat loss amount generated by the operation of the power module is closely related to the aging state of its bonding wire, the more serious the aging of the bonding wire, the higher the heat loss amount generated by the operation of the power module, the worse the health state of the power module, and the greater the difference between the heat loss measurement value of the power module and the heat loss reference value of the corresponding power module. Therefore, according to the difference between the heat loss measurement value of each power module of the converter system of the wind turbine generator set to be tested and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set, the health state of each power module in the converter system of the wind turbine generator set to be tested can be determined.

[0092] An embodiment of the present invention further provides a wind turbine generator set, which includes: the health status assessment device for a converter power module as described above.

[0093] An embodiment of the present invention also provides a system comprising at least one computing device and at least one storage device storing instructions, wherein when the instructions are executed by the at least one computing device, the at least one computing device is prompted to execute the following Fig. 20 The health status assessment method of the converter power module.

[0094] In addition, an embodiment of the present invention further provides a computer-readable storage medium storing instructions, which, when executed by at least one computing device, can cause the at least one computing device to execute the following Fig. 20 The health status assessment method of the converter power module.

[0095] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. For the device embodiment, the relevant parts can refer to the description part of the method embodiment. The embodiments of the present invention are not limited to the specific steps and structures described above and shown in the figures. Those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the embodiments of the present invention. In addition, for the sake of brevity, a detailed description of known method technologies is omitted here.

[0096] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of an embodiment of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0097] The embodiments of the present invention may be implemented in other specific forms without departing from their spirit and essential features. For example, the algorithms described in the specific embodiments may be modified, and the system architecture does not depart from the basic spirit of the embodiments of the present invention. Therefore, the current embodiments are considered to be exemplary and not restrictive in all aspects, and the scope of the embodiments of the present invention is defined by the appended claims rather than the above description, and all changes that fall within the meaning and equivalent scope of the claims are thus included in the scope of the embodiments of the present invention.

Claims

1. A converter system, characterized in that: The converter system comprises: at least one power module, a cooling branch and a heat metering module corresponding to the power module, and a cooling circulation main circuit; wherein, The cooling branch is connected in parallel to the cooling circulation main circuit, and the coolant in each cooling branch is used to absorb the heat loss generated by the operation of the corresponding power module; The heat metering module is arranged at the port of the corresponding cooling branch, and is used to measure the heat loss absorbed by the coolant when it flows through the corresponding cooling branch; each of the cooling branches includes a water cooling plate, and each water cooling plate has a liquid inlet and a liquid outlet as the port of the corresponding cooling branch; By determining the error interval of the difference between the heat loss measurement value of each power module in the wind turbine converter system to be tested and the heat loss reference value of each corresponding power module in the reference wind turbine converter system; determining the health status level corresponding to each of the differences according to the corresponding relationship between the preset error interval and the health level; and determining the health status of each power module in the wind turbine converter system to be tested according to the health status level corresponding to each of the differences.

2. The converter system according to claim 1, characterized in that The heat metering module includes: a liquid inlet flow rate sensor, a liquid inlet temperature sensor, a liquid outlet flow rate sensor and a liquid outlet temperature sensor, wherein: The liquid inlet flow rate sensor is arranged at the liquid inlet of each cooling branch, and is used to measure the flow rate of the coolant at the liquid inlet in each cooling branch; The liquid inlet temperature sensor is arranged at the liquid inlet of each cooling branch, and is used to measure the temperature of the coolant at the liquid inlet in each cooling branch; The liquid outlet flow rate sensor is arranged at the liquid outlet of each cooling branch, and is used to measure the flow rate of the coolant at the liquid outlet in each cooling branch; The liquid outlet temperature sensor is arranged at the liquid outlet of each cooling branch, and is used to measure the temperature of the coolant at the liquid outlet in each cooling branch; The heat loss of the coolant flowing through each cooling branch is determined by the flow rate of the coolant at the liquid inlet, the temperature at the liquid inlet, the flow rate at the liquid outlet, and the temperature at the liquid outlet in each cooling branch.

3. A method for evaluating the health status of a power module of a converter, used for evaluating the health status of a power module in the converter system of claim 1, characterized in that: The method comprises: Obtaining operating status parameters of the wind turbine generator set to be tested and heat loss measurement values ​​of each power module in the converter system of the wind turbine generator set to be tested; Determine the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating status parameters of the wind turbine generator set to be tested; Determining the health status of each power module in the converter system of the wind turbine generator set to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set; Determining the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating state parameters of the wind turbine generator set to be tested includes: Determine a reference wind turbine generator set having the same equipment parameters as the wind turbine generator to be tested; When the reference wind turbine generator set operates under the operating state parameters of the wind turbine generator set to be tested, the heat loss measurement values ​​of the corresponding power modules in the converter system of the reference wind turbine generator set are determined as the heat loss reference values ​​of the corresponding power modules in the converter system of the reference wind turbine generator set.

4. The method according to claim 3, characterized in that Before obtaining the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested, the method further includes: Determining whether a drive board of the converter system of the wind turbine generator set to be tested is faulty; If the driving board of the converter system of the wind turbine generator set to be tested is normal, the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested is obtained.

5. The method according to claim 3, characterized in that: The operating status parameters include ambient wind speed, and the ambient wind speed is not less than the rated wind speed.

6. The method according to claim 3, characterized in that The operating state parameters include a power mode, and the power mode adopts a limited power mode.

7. The method according to claim 3, characterized in that The operating state parameter includes a power value in a preset power set and / or an ambient temperature value in a preset ambient temperature set.

8. The method according to claim 3, characterized in that The step of obtaining the heat loss measurement value of each power module in the converter system of the wind turbine generator set to be tested includes: Obtaining the heat absorbed by the coolant in the cooling branch corresponding to each power module in the converter system of the wind turbine generator set to be tested; The heat absorbed by the coolant in the cooling branch corresponding to each power module in the converter system of the wind turbine generator set to be tested is determined as the heat loss measurement value of the power module.

9. The method according to claim 8, characterized in that Obtaining the heat absorbed by the coolant in the cooling branch corresponding to each power module in the converter system of the wind turbine generator set to be tested, comprising: Obtaining the temperature of the coolant at the liquid inlet, the flow rate at the liquid inlet, the temperature at the liquid outlet, and the flow rate at the liquid outlet in the cooling branches corresponding to each power module in the converter system of the wind turbine generator set to be tested when the wind turbine generator set to be tested is running under the operating state parameters; Calculate the heat of the coolant at the liquid inlet in the cooling branch corresponding to each power module according to the temperature of the coolant at the liquid inlet and the flow rate at the liquid inlet in the cooling branch corresponding to each power module; Calculate the heat of the coolant at the liquid outlet in the cooling branch corresponding to each power module according to the temperature of the coolant at the liquid outlet and the flow rate at the liquid outlet in the cooling branch corresponding to each power module; The difference between the heat of the coolant at the liquid outlet and the heat of the coolant at the liquid inlet in the cooling branch corresponding to each power module is calculated to obtain the heat absorbed by the coolant in the cooling branch corresponding to each power module.

10. The method according to claim 3, characterized in that: After determining the error interval of the difference between the heat loss measurement value of each power module in the wind turbine generator set converter system to be tested and the heat loss reference value of each corresponding power module in the reference wind turbine generator set converter system, the method further includes: Determine the maintenance level corresponding to each difference value according to the correspondence between the preset error interval and the maintenance level; According to the maintenance level corresponding to each of the difference values, a maintenance operation for each power module in the converter system of the wind turbine generator set to be tested is determined.

11. A device for evaluating the health status of a power module of a converter, used for evaluating the health status of a power module in the converter system of claim 1, characterized in that: The device comprises: An acquisition module, used to acquire operating status parameters of the wind turbine generator set to be tested and heat loss measurement values ​​of each power module in the converter system of the wind turbine generator set to be tested; A first determination module is used to determine the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating state parameters of the wind turbine generator set to be tested; A second determination module is used to determine the health status of each power module in the converter system of the wind turbine generator set to be tested according to the difference between the heat loss measurement value of each power module and the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set; Determining the heat loss reference value of each corresponding power module in the converter system of the reference wind turbine generator set according to the operating state parameters of the wind turbine generator set to be tested includes: Determine a reference wind turbine generator set having the same equipment parameters as the wind turbine generator to be tested; When the reference wind turbine generator set operates under the operating state parameters of the wind turbine generator set to be tested, the heat loss measurement values ​​of the corresponding power modules in the converter system of the reference wind turbine generator set are determined as the heat loss reference values ​​of the corresponding power modules in the converter system of the reference wind turbine generator set.

12. A wind turbine generator set, characterized in that: include: The health status assessment device of the converter power module as claimed in claim 11.

13. A system comprising at least one computing device and at least one storage device storing instructions, characterized in that: When the instructions are executed by the at least one computing device, the at least one computing device is prompted to perform the health status assessment method for a power module of a converter according to any one of claims 3 to 10.

14. A computer-readable storage medium storing instructions, characterized in that: When the instructions are executed by at least one computing device, the at least one computing device is prompted to execute the health status assessment method for a converter power module according to any one of claims 3 to 10.

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