CN112084651A - Multi-scale wind power IGBT reliability assessment method and system considering fatigue damage - Google Patents

Abstract

The invention discloses a fatigue damage-related multi-time scale wind power IGBT reliability evaluation method and system, which comprehensively extract the service life information of a power device by using multi-time scales; establishing an electrothermal coupling model of the IGBT module to obtain junction temperature data; establishing a steady-state junction temperature database of the IGBT under different aging states; under a short-term time scale profile, outputting junction temperature data in real time through an electrothermal coupling model based on SCADA monitoring data, and calculating the real-time thermal stress cycle number; acquiring a wind speed probability distribution curve by relying on SCADA monitoring data of a fan under a long-term time scale profile; combining a Bayer life prediction model and a steady-state junction temperature database to obtain the maximum thermal stress cycle times which can be borne by the IGBTs in different aging stages in advance; and calculating the accumulated damage degree and the estimated service life of the IGBT of the wind power converter by taking the thermal stress cycle times as the evaluation results for connecting different time scales. The invention has stronger on-line monitoring capability.

Description

Multi-scale wind power IGBT reliability assessment method and system considering fatigue damage

technical field

The invention belongs to the field of reliability of core components of power electronic equipment, and more particularly, relates to a multi-time scale wind power IGBT reliability evaluation method and system considering fatigue damage.

Background technique

The wind power converter is the core equipment in the wind energy conversion system, and the long-term, high-frequency and high-intensity working conditions produce a lot of thermal stress shocks on it. The converter is one of the most vulnerable components in the wind energy conversion system. . Insulated Gate Bipolar Transistor (IGBT) is widely used in wind power converters due to its advantages of fast switching speed, simple driving circuit, good voltage resistance and large current capacity. The failure is largely caused by the failure of the IGBT. Carrying out the reliability evaluation of the wind power converter IGBT can ensure the safe and reliable operation of the wind power generation system and reduce the operation and maintenance cost of the wind farm. Due to the randomness and volatility of wind speed, the IGBT is subjected to a large number of fluctuating thermal stress cycles, which increases the difficulty of evaluating the reliability of the IGBT.

At this stage, the reliability assessment of wind power converter IGBT modules at home and abroad is mainly based on the reliability assessment manual and junction temperature data. When using the reliability evaluation manual to evaluate wind power converter IGBTs, only a single operating condition can often be considered, and it does not meet the requirements of online monitoring; the application scope and accuracy of the reliability evaluation manual are very limited, and the junction temperature data can be used for The application background of wind power generation is more accurate to carry out reliability assessment. There are two methods for online acquisition of junction temperature: direct measurement and indirect measurement. Direct measurement is to obtain junction temperature data by embedding an integrated sensor inside the IGBT module or through an infrared thermometer; the integrated sensor needs to consider the electromagnetic compatibility of the integrated sensor in the design and production of the IGBT, and the packaging of the IGBT module affects the measurement of the infrared thermometer inside. Junction temperature accuracy. In addition, the direct measurement method has the problems of data transmission delay and increased cost in practical engineering. The indirect measurement is to estimate the junction temperature of the IGBT in real time by establishing an electrothermal coupling model, which has the advantages of low delay and strong online monitoring capability.

When evaluating the reliability of the IGBT module of a wind power converter, many factors that affect the device need to be considered, such as wind speed, ambient temperature, and aging characteristics of power devices. Based on SCADA monitoring data, the influence of wind speed and ambient temperature on IGBT reliability assessment can be considered, but the real-time observation scale of SCADA data is very short compared to the entire life cycle of IGBT modules, and the cumulative effect of IGBT fatigue damage is not effectively taken into account . In general, when using junction temperature data to evaluate the reliability of wind power IGBTs, the influence of existing methods on fatigue damage cannot be effectively taken into account, and the calculation efficiency cannot meet the requirements of online monitoring.

SUMMARY OF THE INVENTION

In view of the above defects or improvement needs of the prior art, the present invention proposes a multi-time scale wind power IGBT reliability evaluation method and system considering fatigue damage. Extracting the life information of power devices reduces the dependence of a single observation scale on the length of SCADA monitoring data time series, improves the calculation efficiency of reliability evaluation, and has strong online monitoring capabilities.

In order to achieve the above object, according to one aspect of the present invention, a multi-time scale wind power IGBT reliability evaluation method considering fatigue damage is provided, including:

(1) Divide the reliability evaluation time scale, and use multiple time scales to comprehensively extract the life information of power devices;

(2) According to the topology of the wind power converter and the IGBT model, the electrothermal coupling model of the IGBT module is established to obtain the junction temperature data, and combined with the IGBT fatigue damage theory, the steady-state junction temperature database of the IGBT under different aging states is established;

(3) Under the short-term time scale profile, based on SCADA monitoring data, the influence of ambient temperature and wind speed is fully considered, and the junction temperature data is output in real time through the electrothermal coupling model, and the number of real-time thermal stress cycles is calculated;

(4) Under the long-term time scale profile, the Weibull probability distribution model of wind speed is established based on the SCADA monitoring data of wind turbines, and the probability distribution curve of wind speed is obtained. After normalization, the probability distribution of thermal stress shock test times is carried out. The steady-state junction temperature database obtains in advance the maximum number of thermal stress cycles that the IGBT can withstand in different aging stages;

(5) Using the number of thermal stress cycles as the evaluation results of connecting different time scales, the cumulative damage degree and estimated life of the IGBT of the wind power converter are calculated.

In some optional embodiments, the dividing the reliability assessment time scale includes:

In the long-term profile, the aging characteristics of power devices are mainly considered, and the transient details of junction temperature fluctuations are ignored, and only the steady-state junction temperature is considered to maintain high computational efficiency;

In the short-time-scale profile, the effects of wind speed and ambient temperature are mainly considered, and the observed junction temperature fluctuation data are fully taken into account.

In some optional embodiments, establishing the steady-state junction temperature database of the IGBT under different aging states includes:

Based on the fatigue damage theory, the cumulative damage degree D is used to reflect the damage degree of the IGBT module; when D≦a, the thermal network parameters of the electrothermal coupling model are not corrected; when the cumulative damage degree a<D≦b, according to the first The preset value increases the thermal network parameters of the electrothermal coupling model; when the cumulative damage degree b<D≦c, the thermal network parameters of the electrothermal coupling model are increased according to the second preset value; when the cumulative damage degree c<D≦d, the thermal network parameters are increased according to the second preset value. The third preset value increases the thermal network parameters of the electrothermal coupling model; when the cumulative damage degree d<D≦e, the thermal model parameters of the electrothermal coupling model are increased according to the fourth preset value, wherein the first preset value, The second preset value, the third preset value and the fourth preset value increase sequentially, and the values of a, b, c, d, and e increase sequentially;

Sampling between the cut-in wind speed and cut-out wind speed of the fan to obtain the characteristic operating conditions of the wind power IGBT, calculate the steady-state junction temperature value output by the electrothermal coupling model under different aging states of each characteristic operating condition, and establish the IGBT steady-state junction temperature database;

确定累积损伤度，其中，N_f为IGBT模块在某幅值大小不变的应力循环作用下的失效周期数，N表示承受该应力的循环次数。In some optional embodiments, by

Determine the cumulative damage degree, where N _f is the number of failure cycles of the IGBT module under the action of a certain amplitude and constant stress cycle, and N represents the number of cycles under the stress.

In some optional embodiments, step (4) includes:

Relying on the SCADA monitoring data of the wind turbine, the Weibull probability distribution model of wind speed is established, and the probability distribution curve of wind speed is obtained;

After normalization, the probability distribution of thermal stress shock test times is carried out, and the aging process of the IGBT is judged, and the steady-state junction temperature database corresponding to the aging stage is selected;

Combined with the Bayerer lifetime prediction model and the selected steady-state junction temperature database, the maximum thermal stress cycles that the IGBT can withstand in different aging stages are obtained in advance.

In some optional embodiments, step (5) includes:

Under the short-term time scale profile, obtain the real-time thermal stress cycle times of the IGBT module in the current operating state;

Under the long-term time scale profile, the maximum number of cyclic shocks of the IGBT taking into account fatigue damage is obtained;

Taking the number of thermal stress cycles as the connection, and synthesizing the output results at various time scales, the real-time cumulative damage degree and estimated life of the wind power converter IGBT are calculated.

计算风电变流器IGBT的实时累积损伤度，其中，N_t表示在短期时间尺度剖面下，获得的IGBT模块在当前运行状态下的实时热应力循环次数，N_m表示在长期时间尺度剖面下，获得的计及疲劳损伤的IGBT最大承受循环冲击次数。In some optional embodiments, by

Calculate the real-time cumulative damage degree of the IGBT of the wind power converter, where N _t represents the real-time thermal stress cycle times of the IGBT module obtained under the current operating state under the short-term time-scale profile, and N _m represents the long-term time-scale profile, The obtained maximum number of shock cycles of the IGBT taking into account fatigue damage.

计算预估寿命，其中，T表示监测数据的时间序列长度。In some optional embodiments, by

Calculate the estimated life, where T is the length of the time series of the monitoring data.

According to another aspect of the present invention, a multi-time scale wind power IGBT reliability evaluation system considering fatigue damage is provided, including:

The time scale division module is used to divide the reliability evaluation time scale, and use multiple time scales to comprehensively extract the life information of power devices;

The steady-state junction temperature database building module is used to establish the electrothermal coupling model of the IGBT module for the wind power converter topology and IGBT model to obtain the junction temperature data. Combined with the IGBT fatigue damage theory, the stability of the IGBT under different aging states is established. State junction temperature database;

The short-term reliability analysis module is used to fully consider the influence of ambient temperature and wind speed based on SCADA monitoring data under the short-term time scale profile, output junction temperature data in real time through the electrothermal coupling model, and calculate the number of real-time thermal stress cycles;

The long-term reliability analysis module is used to establish the Weibull probability distribution model of wind speed based on the SCADA monitoring data of the wind turbine under the long-term time scale profile, and obtain the probability distribution curve of wind speed. The Bayerer lifetime prediction model and the steady-state junction temperature database pre-obtain the maximum thermal stress cycles that the IGBT can withstand in different aging stages;

The reliability evaluation module is used to calculate the cumulative damage and estimated life of the IGBT of the wind power converter using the number of thermal stress cycles as the evaluation results of different time scales.

According to another aspect of the present invention, there is provided a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, implements the steps of any one of the above-mentioned methods.

In general, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. Consider wind speed, ambient temperature, and time constant characteristics of power devices, and divide the time scale of reliability assessment to obtain more life information, such as power device fatigue damage, wind speed fluctuations, and the consumption of life due to ambient temperature fluctuations, etc. To ensure the accuracy of the evaluation results;

2. When considering the influence of fatigue damage on multiple time scales, the steady-state junction temperature data and probability distribution are used to simulate the IGBT aging process under the long-term time scale profile, and the maximum number of thermal stress cycles under the influence of fatigue damage is obtained. Reduced the dependence of a single observation scale on the length of SCADA data time series, and improved computational efficiency;

3. The online monitoring capability of multiple time scales is strong. The junction temperature data is output through SCADA monitoring data and electrothermal coupling model, and the number of IGBT real-time thermal stress cycles is calculated by rain flow counting method. Secondly, the maximum thermal stress cycle times of the IGBT under fatigue damage are comprehensively considered, and the cumulative damage degree is calculated in real time to reflect the health status of the IGBT module. This method is more in line with the performance requirements of wind power converter IGBT health monitoring in the context of smart grid and energy internet.

Description of drawings

1 is a schematic flowchart of a multi-time scale wind power IGBT reliability evaluation method considering fatigue damage provided by an embodiment of the present invention;

2 is a topology structure of a doubly-fed wind power converter provided by an embodiment of the present invention;

Fig. 3 is a kind of IGBT module electrothermal coupling simulation model provided by the embodiment of the present invention;

4 is a real-time junction temperature curve of a grid-side converter IGBT according to an embodiment of the present invention;

Fig. 5 is a kind of rainflow counting method output result provided by the embodiment of the present invention;

6 is a Weibull probability distribution curve of the annual wind speed of a wind farm provided by an embodiment of the present invention;

FIG. 7 is an aging process of an IGBT module provided by an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

In the examples of the present invention, "first", "second", etc. are used to distinguish different objects, and are not necessarily used to describe a specific order or sequence.

Example 1

As shown in FIG. 1 is a schematic flowchart of a multi-time scale wind power IGBT reliability evaluation method considering fatigue damage provided by an embodiment of the present invention. The method shown in FIG. 1 includes the following steps:

(1) Divide the reliability evaluation time scale into two time scales, long-term and short-term, and use multiple time scales to comprehensively extract the life information of power devices;

Wherein, step (1) is used to effectively take into account different influencing factors (wind speed, ambient temperature, aging characteristics of power devices) in the process of reliability evaluation.

(2) According to the topology structure of wind power converter and the specific model of IGBT, the electrothermal coupling model of IGBT module is established to obtain junction temperature data, and combined with the theory of IGBT fatigue damage, the aging process of IGBT is divided into several stages, and the IGBT aging process is divided into several stages. Steady-state junction temperature database in aging state;

(3) Under the short-term time scale profile, based on SCADA monitoring data, the influence of ambient temperature and wind speed is fully considered, and the junction temperature data is output in real time through the electrothermal coupling model, and the number of real-time thermal stress cycles N _t is calculated;

Among them, the real-time thermal stress cycle number N _t can be calculated by the rainflow counting method.

(4) Under the long-term time scale profile, the Weibull probability distribution model of wind speed is established based on the SCADA monitoring data of the wind turbine, and the probability distribution curve of wind speed is obtained. After normalization, the probability distribution of thermal stress shock test times is carried out; The maximum thermal stress cycle times N _m that the IGBT can withstand in different aging stages is obtained in advance from the junction temperature database;

(5) The number of thermal stress cycles is used to connect the evaluation results of different time scales to calculate the real-time cumulative damage D _t and estimated life of the wind power converter IGBT, so as to realize the complementary advantages of reliability analysis on different time scales, taking into account the fatigue accumulation While taking into account the damage, the calculation efficiency of the cumulative damage degree is taken into account.

Further, in step (1), when dividing the reliability evaluation time scale of the IGBT module of the wind power converter, consider many factors that affect the device, such as wind speed, ambient temperature, power device characteristics, etc.; these factors involve different factors. Multidisciplinary models of time constants, so it is difficult to evaluate these models at the same time. Inspired by the use of lenses of different focal lengths in photography to obtain images of different sizes and details, the evaluation time scale is divided according to the time constant characteristics of each influencing factor, forming a multi-time Scale; using multiple time scales to comprehensively extract the lifetime information of the device, so as to realize the effective consideration of different influencing factors in the reliability evaluation process. Using multiple time scales to comprehensively extract the lifetime information of the device, in order to realize the effective consideration of different influencing factors in the reliability evaluation process.

The thermal time constant of the power device is much smaller than the fluctuation period of wind speed and ambient temperature. Therefore, the influence of the transient process of the fan system on the junction temperature of the device can be ignored when considering the effect of fatigue damage, and the working conditions of the fan system are assumed to be a series of steady-state In addition, the aging period of power devices can be as long as several years, which is much longer than the real-time observation period. It can be considered that the health state of the IGBT remains unchanged under the short-term observation scale. In the long-term profile, the aging characteristics of power devices are considered, and the transient details of the junction temperature fluctuation are ignored, and only the steady-state junction temperature is considered to maintain high computational efficiency; The observed junction temperature fluctuation data is fully accounted for. The setting of multiple time scales is beneficial to capture different aspects of life information in the process of wind power converter IGBT reliability assessment and improve the computational efficiency.

Further, in step (2), the steady-state junction temperature database establishment method is as follows:

Starting from the wind power converter topology, combined with the IGBT operating characteristics (switching frequency f _s , DC side voltage U _dc , on-current I _c , duty cycle δ ), the IGBT power loss model is derived; based on the physical structure and internal structure of the IGBT module The equivalent model of the IGBT thermal network is derived from the heat conduction process; the electrothermal coupling simulation model is built in MATLAB/Simulink. The power loss value output by the power loss model is sent to the thermal network equivalent model of the IGBT module to simulate the junction temperature calculation.

The IGBT module needs to withstand a large number of thermal stress cycles during the working process. Assuming that N _f is the number of failure cycles of the IGBT module under the action of a certain amplitude and constant stress cycle, when it is subjected to N cycles of the stress, and When N is less than N _f , although the IGBT module will not fail due to fatigue damage, it also produces a certain degree of fatigue damage. The cumulative damage degree can be used to express the specific size of the fatigue damage as follows:

If the device is under the action of k constant amplitude stresses, and the number of shocks generated by each constant amplitude stress is N _f,i times, the cumulative damage degree under this condition can be expressed as:

Ni represents the _ith constant amplitude stress, Di represents the fatigue damage caused by the ith constant amplitude stress, and N _{f,i represents} the number of failure cycles under the action of the ith constant amplitude stress cycle. .

When the cumulative damage degree D reaches 1, it indicates that the device has fatigue failure. In the actual working process of the wind power converter, the solder layer of the IGBT module is prone to fatigue damage, and the thermal resistance increases with the aging process of the device material. Considering the non-negligible influence of the aging process of the IGBT module itself on the life prediction, it is necessary to update the thermal model parameters in the electrothermal coupled model in time.

Considering the non-negligible influence of the aging process of the IGBT module itself on the life prediction, it is necessary to update the thermal model parameters in the electrothermal coupled model in time. When D≦a, the thermal network parameters of the electrothermal coupling model are not modified; when the cumulative damage degree a<D≦b, the thermal network parameters of the electrothermal coupling model are increased according to the first preset value; when the cumulative damage degree b<D≦b When c, the thermal network parameters of the electrothermal coupling model are increased according to the second preset value; when the cumulative damage degree c<D≦d, the thermal network parameters of the electrothermal coupling model are increased according to the third preset value; when the cumulative damage degree d< When D≦e, the thermal model parameters of the electrothermal coupling model are increased according to the fourth preset value, wherein the first preset value, the second preset value, the third preset value and the fourth preset value increase in sequence, a The values of , b, c, d, and e increase in turn;

As a preferred embodiment, when D≦0.2, the IGBT module is considered to be in the healthy phase I, and the thermal network parameters of the electrothermal coupling model are not corrected; when the cumulative damage degree is 0.2<D≦0.4, the IGBT module is considered to be in the healthy phase II. , increase the thermal network parameters of the electrothermal coupling model by 10%; when the cumulative damage degree is 0.4<D≦0.6, it is determined that the IGBT module is in healthy stage III, and the thermal network parameters of the electrothermal coupling model are increased by 20%; when the cumulative damage degree is 0.6<D≦ 0.8, the IGBT module is considered to be in the healthy stage IV, and the thermal network parameter of the electrothermal coupling model is increased by 30%; when the cumulative damage degree is 0.8<D≦1, the IGBT module is considered to be in the healthy stage V, and the thermal model parameter of the electrothermal coupling model is increased by 40%. %.

Between the cut-in wind speed and cut-out wind speed of the fan, uniform sampling is performed at an interval of 1 m/s to obtain the characteristic operating conditions of the wind power IGBT; Steady state junction temperature database.

Further, in step (4), the flow of the reliability assessment method under the long-term scale profile is as follows:

1) Establish the Weibull probability distribution model of wind speed based on the SCADA monitoring data of the wind turbine, and obtain the probability distribution curve of wind speed;

2) After normalization, carry out the probability distribution of the number of thermal stress shock inspections, judge the aging process of the IGBT, and select the steady-state junction temperature database corresponding to the aging stage;

3) Combined with the Bayerer lifetime prediction model and the steady-state junction temperature database, the maximum thermal stress cycles N _m that the IGBT can withstand in different aging stages are obtained in advance.

Further, in step (5), the output results of the algorithms on different time scales are synthesized to perform reliability evaluation: under the short-term time-scale profile, the real-time thermal stress cycle number N _t of the IGBT module in the current operating state is obtained; Under the time scale profile, the maximum number of cyclic shocks N _m of the IGBT considering fatigue damage is obtained; the multi-time scale is connected with the number of thermal stress cycles, and the output results of the two time scales are combined to calculate the real-time accumulation of the wind power converter IGBT Damage degree D _t and estimated life S.

Among them, T represents the time series length of monitoring data.

The multi-time scale reliability method proposed by the invention reduces the dependence of a single observation scale on the SCADA data time series length when considering the influence of IGBT fatigue damage, improves the reliability evaluation calculation efficiency, and has a strong online monitoring capability.

Embodiment 2

The following takes a 2MW doubly-fed wind power generation system as a specific example, and the specific parameters are shown in Table 1. The reliability of the grid-side converter IGBT is analyzed by using the multi-time scale method considering fatigue damage, and the present invention is further described in detail with reference to the accompanying drawings.

Table 1 Parameters of wind power generation system

category parameter Rated power/MW 2 Cut-in wind speed/(m/s) 3 Rated wind speed/(m/s) 11 Cut out wind speed/(m/s) 25 Grid side voltage/V 690 Grid side frequency/Hz 50 IGBT switching frequency/Hz 3500 DC side voltage/V 1100 IGBT model Infineon-FF1400R17IP4

1, an embodiment of the present invention includes the following steps:

(1) Divide the time scale of wind power converter IGBT reliability evaluation, and use multiple time scales to comprehensively extract the life information of power devices:

In the long-term profile, the aging characteristics of power devices are considered, and the transient details of the junction temperature fluctuation are ignored, and only the steady-state junction temperature is considered to maintain high computational efficiency; The observed junction temperature fluctuation data is fully accounted for.

(2) According to the topology of the wind power converter and the IGBT model, the electrothermal coupling model of the IGBT module is established to obtain the junction temperature data. Combined with the IGBT fatigue damage theory, the aging process is divided into five stages, and the aging process of the IGBT under different aging states is established. steady-state junction temperature database;

Junction temperature fluctuations are the main cause of IGBT failure. Due to the different thermal expansion coefficients of IGBT internal materials, the thermal stress of its internal structure will be uneven, resulting in bonding wires, solder layers, and material interface parts inside the chip are often damaged. Aiming at the topology of the doubly-fed wind power converter shown in Figure 2, combined with the IGBT operating characteristics (switching frequency f _s , DC side voltage U _dc , on-current I _c , duty cycle δ ), the IGBT power loss model is derived; Based on the physical structure and internal heat conduction process of the IGBT module, the equivalent model of the IGBT thermal network is derived; finally, the electric-thermal coupling simulation model is built in MATLAB/Simulink, as shown in Figure 3. The power loss value output by the power loss model is sent to the equivalent network of the thermal model of the IGBT module to simulate the junction temperature calculation.

The IGBT module needs to withstand a large number of thermal stress cycles during the working process. Assuming that N _f is the number of failure cycles of the IGBT module under the action of a certain amplitude and constant stress cycle, when it is subjected to N cycles of the stress, and When N is less than N _f , although the IGBT module will not fail due to fatigue damage, it also produces a certain degree of fatigue damage. The cumulative damage degree can be used to express the specific size of the fatigue damage as follows:

If the device is under the action of k constant amplitude stresses, and the number of shocks generated by each constant amplitude stress is N _f,i times, the cumulative damage degree under this condition can be expressed as:

When the cumulative damage degree D reaches 1, it indicates that the device has fatigue failure. In the actual working process of the wind power converter, the solder layer of the IGBT module is prone to fatigue damage, and the thermal resistance increases with the aging process of the device material. Considering the non-negligible influence of the aging process of the IGBT module itself on the life prediction, it is necessary to update the thermal model parameters in the electrothermal coupled model in time. Considering the non-negligible influence of the aging process of the IGBT module itself on the life prediction, it is necessary to update the thermal model parameters in the electrothermal coupled model in time. When D≦0.2, the IGBT module is considered to be in the healthy phase I, and the thermal network parameters of the electrothermal coupling model are not corrected; when the cumulative damage degree is 0.2<D≦0.4, the IGBT module is considered to be in the healthy phase II, and the thermal network of the electrothermal coupled model is increased. The parameter is 10%; when the cumulative damage degree is 0.4<D≦0.6, the IGBT module is considered to be in healthy stage III, and the thermal network parameter of the electrothermal coupling model is increased by 20%; when the cumulative damage degree is 0.6<D≦0.8, the IGBT module is considered to be healthy In stage IV, increase the thermal network parameters of the electrothermal coupling model by 30%; when the cumulative damage degree is 0.8<D≦1, it is determined that the IGBT module is in the healthy V stage, and the thermal model parameters of the electrothermal coupling model are increased by 40%.

Between the cut-in wind speed (3m/s) and the cut-out wind speed (25m/s) of the fan, uniform sampling is carried out at intervals of 1m/s to obtain 23 characteristic operating conditions of the wind power IGBT; calculate the stability of each operating condition under different aging states State junction temperature value, establish IGBT steady state junction temperature database;

(3) Under the short time scale profile, based on SCADA monitoring data, the influence of ambient temperature and wind speed is fully considered, the junction temperature data is output in real time through the electrothermal coupling model, and the number of real-time thermal stress cycles is calculated by the rain flow counting method;

The wind speed and ambient temperature recorded in the SCADA database within one year are imported into the fan model and the electrothermal coupled model, and the real-time junction temperature curve of the grid-side converter IGBT is obtained, as shown in Figure 4; secondly, the thermal stress load is extracted by the rain flow counting method distribution, and calculate the real-time thermal stress cycle number N _t , that is, the short-term reliability parameter, as shown in Figure 5.

(4) Under the long-term scale profile, the Weibull probability distribution model of wind speed is established based on the SCADA monitoring data of the wind turbine, and the probability distribution curve of wind speed is obtained. After normalization, the probability distribution of thermal stress shock test times is carried out; The state junction temperature database pre-obtains the maximum number of thermal stress cycles that the IGBT can withstand in different aging stages;

The junction temperature of the wind power converter IGBT is most affected by the wind speed fluctuation, and the wind speed probability characteristics of the wind farm can be accurately described by the two-parameter Weibull distribution:

In the formula, k is the Weibull distribution shape parameter determined by the average wind speed during the wind speed measurement in the region, c is the Weibull distribution scale parameter determined by the standard deviation of the wind speed, and v is the wind speed. Integrating this formula can get the Weibull probability distribution function as follows:

In order to take into account the seasonal characteristics of wind speed, the Weibull probability distribution is fitted with the wind speed data in the wind farm SCADA database for one year. The fitted probability distribution curve is shown in Figure 6, and the parameters are shown in Table 2.

Table 2 Weibull probability distribution parameters

The wind power converter studied in the embodiment of the present invention adopts the IGBT module of Infineon Company. The Bayerer model is a life prediction model fitted by Infineon for its own product testing. It is more realistic to select this life prediction model to simulate the aging process of IGBT. Its expression is:

In the formula: T _jmax is the maximum junction temperature; parameter K is the model correction coefficient; β ₁ and β ₂ are the junction temperature fluctuation index and the maximum junction temperature index respectively; β ₃ to β ₆ are the power cycle heating time, device withstand voltage, respectively Rating value, bond wire current value, and an index of bond wire diameter.

Table 2 shows the probability distribution of wind speed with different seasonal characteristics, and the probability distribution of the number of thermal stress cyclic shocks after normalization; Combined with the Bayerer life prediction model to accurately simulate the aging process of the IGBT in the entire life cycle, as shown in Figure 7; it can be found that during the working process of the wind power converter, the wind conditions with different seasonal characteristics will To produce different damage to IGBT, it is necessary to consider the influence of wind speed probability distribution when studying the reliability of wind power IGBT; finally, the maximum number of thermal stress cycles N _m that the IGBT can withstand before failure is obtained, that is, the long-term reliability parameter.

(5) Using the number of thermal stress cycles as the connection amount, calculate the cumulative damage degree and estimated life of the grid-side converter IGBT of the wind power converter.

Under the short-term time profile, the real-time thermal stress cycle number N _t of the IGBT module in the current operating state is obtained; under the long-term time profile, the maximum number of IGBT cycles N _m that takes into account fatigue damage is obtained; the multi-time scale algorithm uses thermal The number of stress cycles is the connection for reliability evaluation:

In the formula, D _t represents the real-time cumulative damage degree, S represents the estimated life, and T represents the time series length of the monitoring data.

The output results of different time-scale algorithms are given in Table 3, and the cumulative damage and service life statistics of IGBT modules of the same type of wind power converter are used as mathematical expectations; it can be concluded that the multi-time-scale algorithm can make up for the inability of a single observation scale. Taking into account the defect of fatigue damage, it can more accurately reflect the health status of the IGBT module of the wind power converter.

Table 3 Comparison of the output results of different time scale algorithms

Embodiment 3

The embodiment of the present invention provides a multi-time scale wind power IGBT reliability evaluation system considering fatigue damage, including:

The time scale division module is used to divide the reliability evaluation time scale, and use multiple time scales to comprehensively extract the life information of power devices;

The steady-state junction temperature database building module is used to establish the electrothermal coupling model of the IGBT module for the wind power converter topology and IGBT model to obtain the junction temperature data. Combined with the IGBT fatigue damage theory, the stability of the IGBT under different aging states is established. State junction temperature database;

The short-term reliability analysis module is used to fully consider the influence of ambient temperature and wind speed based on SCADA monitoring data under the short-term time scale profile, output junction temperature data in real time through the electrothermal coupling model, and calculate the number of real-time thermal stress cycles;

The long-term reliability analysis module is used to establish the Weibull probability distribution model of wind speed based on the SCADA monitoring data of the wind turbine under the long-term time scale profile, and obtain the probability distribution curve of wind speed. The Bayerer lifetime prediction model and the steady-state junction temperature database pre-obtain the maximum thermal stress cycles that the IGBT can withstand in different aging stages;

The reliability evaluation module is used to calculate the cumulative damage and estimated life of the IGBT of the wind power converter using the number of thermal stress cycles as the evaluation results of different time scales.

For the specific implementation of each module, reference may be made to the description in the method embodiment, which will not be repeated in the embodiment of the present invention.

Embodiment 4

The present application also provides a computer-readable storage medium, such as flash memory, hard disk, multimedia card, card-type memory (eg, SD or DX memory, etc.), random access memory (RAM), static random access memory (SRAM), read-only memory Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Programmable Read-Only Memory (PROM), Magnetic Memory, Magnetic Disk, Optical Disc, Server, App Store, etc., on which computer programs are stored, programs When executed by a processor, the multi-time scale wind power IGBT reliability evaluation method considering fatigue damage in the method embodiment is realized.

It should be pointed out that, according to the needs of implementation, the various steps/components described in this application may be split into more steps/components, or two or more steps/components or partial operations of steps/components may be combined into new steps/components to achieve the purpose of the present invention.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (10)

1. A fatigue damage-considered multi-time scale wind power IGBT reliability assessment method is characterized by comprising the following steps:

(1) dividing the reliability evaluation time scale, and comprehensively extracting the service life information of the power device by utilizing multiple time scales;

(2) aiming at the topology and the type of the IGBT of the wind power converter, establishing an electrothermal coupling model of the IGBT module to obtain junction temperature data, and establishing a steady-state junction temperature database of the IGBT under different aging states by combining an IGBT fatigue damage theory;

(3) under a short-term time scale profile, based on SCADA monitoring data, the influence of environmental temperature and wind speed is comprehensively considered, junction temperature data is output in real time through the electrothermal coupling model, and the number of real-time thermal stress cycles is calculated;

(4) establishing a Weibull probability distribution model of the wind speed by relying on SCADA monitoring data of a fan under a long-term time scale profile to obtain a wind speed probability distribution curve, carrying out thermal stress impact test time probability distribution after normalization, and combining a Bayer life prediction model and the steady-state junction temperature database to obtain the maximum thermal stress cycle times which can be borne by the IGBTs in different aging stages in advance;

(5) and calculating the accumulated damage degree and the estimated service life of the IGBT of the wind power converter by taking the thermal stress cycle times as the evaluation results for connecting different time scales.

2. The method of claim 1, wherein the partitioning the reliability assessment timescale comprises:

in a long-time scale section, the aging characteristic of a power device is considered, and only the steady-state junction temperature is considered after transient details of junction temperature fluctuation are ignored, so that higher calculation efficiency is kept;

in a short time scale section, the influence of wind speed and ambient temperature is considered, and observed junction temperature fluctuation data is comprehensively considered.

3. The method of claim 2, wherein the establishing a steady state junction temperature database of the IGBTs under different aging conditions comprises:

based on a fatigue damage theory, reflecting the damage degree of the IGBT module by utilizing the accumulated damage degree D; when D ≦ a, not correcting the electric heating coupling model heat network parameter; when the accumulated damage degree a < D ≦ b, increasing the parameters of the electrothermal coupling model thermal network according to a first preset value; when the accumulated damage degree b is less than or equal to D and less than or equal to c, increasing the parameters of the electrothermal coupling model thermal network according to a second preset value; when the accumulated damage degree c is less than or equal to D, increasing the parameters of the electrothermal coupling model thermal network according to a third preset value; when the accumulated damage degree D is less than or equal to D and less than or equal to e, increasing the thermal model parameters of the thermocouple-thermocouple model according to a fourth preset value, wherein the first preset value, the second preset value, the third preset value and the fourth preset value are sequentially increased, and the values of a, b, c, D and e are sequentially increased;

sampling is carried out between the cut-in wind speed and the cut-out wind speed of the fan, the characteristic working conditions of the wind power IGBT are obtained, the steady-state junction temperature value output by the electric heating coupling model under different aging states of all the characteristic working conditions is calculated, and an IGBT steady-state junction temperature database is established.

4. The method of claim 3, wherein the method is performed by

Determining fatigueDegree of cumulative damage, wherein N_fThe number of failure cycles of the IGBT module under the stress cycle action with a certain amplitude unchanged is shown, and N represents the number of cycles bearing the stress.

5. The method according to any one of claims 1 to 4, wherein step (4) comprises:

establishing a Weibull probability distribution model of the wind speed by relying on SCADA monitoring data of the fan to obtain a wind speed probability distribution curve;

after normalization, carrying out thermal stress impact test frequency probability distribution, judging the aging process of the IGBT, and selecting a steady-state junction temperature database corresponding to an aging stage;

and combining a Bayer life prediction model and a selected steady-state junction temperature database to obtain the maximum thermal stress cycle times which can be borne by the IGBT in different aging stages in advance.

6. The method of claim 5, wherein step (5) comprises:

under a short-term time scale section, obtaining the real-time thermal stress cycle times of the IGBT module in the current operation state;

obtaining the maximum cycle impact times of the IGBT considering fatigue damage under a long-term time scale section;

and (4) calculating the real-time accumulated damage degree and the estimated service life of the IGBT of the wind power converter by taking the thermal stress cycle times as a link and integrating the output results under each time scale.

7. The method of claim 6, wherein the method is performed by

Calculating the real-time accumulated damage degree of the IGBT of the wind power converter, wherein N_tRepresenting the real-time thermal stress cycle number N of the obtained IGBT module under the current operation state under a short-term time scale section_mAnd the maximum number of cycles of impact on the IGBT considering fatigue damage obtained under the long-term time scale section is shown.

8. The method of claim 7, wherein the method is performed by

And calculating the estimated life, wherein T represents the time series length of the monitoring data.

9. The utility model provides a take into account fatigue damage's multiscale wind-powered electricity generation IGBT reliability evaluation system which characterized in that includes:

the time scale division module is used for dividing the reliability evaluation time scale and comprehensively extracting the service life information of the power device by utilizing multiple time scales;

the steady-state junction temperature database establishing module is used for establishing an electrothermal coupling model of the IGBT module aiming at the topology and the type of the IGBT of the wind power converter so as to obtain junction temperature data, and establishing a steady-state junction temperature database of the IGBT in different aging states by combining an IGBT fatigue damage theory;

the short-term reliability analysis module is used for comprehensively considering the influence of environmental temperature and wind speed on the basis of SCADA monitoring data under a short-term time scale profile, outputting junction temperature data in real time through the electrothermal coupling model and calculating the number of real-time thermal stress cycles;

the long-term reliability analysis module is used for establishing a Weibull probability distribution model of the wind speed by relying on the SCADA monitoring data of the fan under a long-term time scale section to obtain a wind speed probability distribution curve, carrying out thermal stress impact test frequency probability distribution after normalization, and combining a Bayer life prediction model and the steady-state junction temperature database to obtain the maximum thermal stress cycle times which can be borne by the IGBTs in different aging stages in advance;

and the reliability evaluation module is used for calculating the accumulated damage degree and the estimated service life of the IGBT of the wind power converter by taking the thermal stress cycle times as evaluation results for connecting different time scales.

10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 8.

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