Condensation test method and system for power conversion equipment

Abstract

The application discloses a condensation test method and system of a power conversion device, and belongs to the field of condensation prevention test. The power conversion device is located in a controllable temperature and humidity environment, and comprises a plurality of power input ends, each of which is connected with a cable. The method comprises performing at least one cycle test on the power conversion device. The cycle test comprises a first test and a second test arranged in sequence. The first test comprises controlling the power conversion device to be in a shutdown state, and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle. The second test comprises controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device to be switched to a startup state, and controlling the second input end with an electrical stress state to input a plurality of preset powers smaller than full power in sequence. The method can accurately simulate special working conditions in actual outdoor field operation, and improves the problem that the deviation between the test working condition and the actual field working condition is large.

Description

Technical Field

[0001] This application relates to the field of anti-condensation testing technology, specifically to a condensation testing method and system for power conversion equipment. Background Technology

[0002] Power conversion equipment, such as photovoltaic inverters, typically needs to operate outdoors or in high-humidity environments for extended periods. When the temperature in certain areas of the power conversion equipment drops below the dew point temperature of the surrounding air, water vapor in the air condenses into liquid water, forming condensation. Condensation can lead to reduced electrical clearances and decreased insulation resistance, subsequently causing reliability issues such as creepage and short circuits.

[0003] Condensation reliability testing of power conversion equipment typically involves placing the equipment in an environmental test chamber and conducting static tests under a set high humidity environment and temperature alternation curve, or conducting full-load operation tests under constant temperature and humidity conditions. This type of testing method struggles to simulate the specific operating conditions that power conversion equipment actually experiences in outdoor field operations. This leads to a significant disconnect between the test conditions and actual field conditions, easily resulting in missed detections of early electrical failures caused by condensation and weak points in the equipment's insulation design. Consequently, the test results cannot accurately reflect the condensation reliability of the power conversion equipment during field operation. Summary of the Invention

[0004] A method and system for condensation testing of power conversion equipment is provided to accurately simulate the special working conditions of actual outdoor operation, thereby improving the problem of large deviation between the test conditions and the actual on-site conditions.

[0005] A first aspect provides a condensation test method for a power conversion device, wherein the power conversion device is located in a controllable temperature and humidity environment, the power conversion device includes multiple power input terminals, each power input terminal is connected to a cable, a first input terminal of the multiple power input terminals is in a state without electrical stress, and a second input terminal is in a state with electrical stress; the condensation test method includes: At least one cyclic test is performed on the power conversion device; wherein the cyclic test includes a first test and a second test set sequentially; The first test includes controlling the power conversion device to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device to be switched to a power-on state, and controlling the input of a plurality of preset power values ​​that are sequentially increased to the power conversion device through the second input terminal, wherein each preset power value is less than the full power value.

[0006] In some embodiments, after performing at least one cycle test on the power conversion device, the condensation test method further includes: A full-load test is performed on the power conversion device; wherein the full-load test includes a first test and a third test set sequentially. The third test includes stopping the temperature and humidity adjustment of the controllable temperature and humidity environment, switching the power conversion device to the power-on state, switching the first input terminal to the state with electrical stress, and controlling all power input terminals to output the full power to the power conversion device.

[0007] In some embodiments, each of the temperature and humidity alternation cycles includes at least one first cycle stage and one second cycle stage; controlling the controllable temperature and humidity environment to operate at least one temperature and humidity alternation cycle includes: In each of the first cycle phases, the controllable temperature and humidity environment is controlled to rise from a first preset temperature to a second preset temperature, maintain the second preset temperature for a first duration, and then decrease from the second preset temperature back to the first preset temperature; In the second cycle phase, the controllable temperature and humidity environment is controlled to decrease from the first preset temperature to the third preset temperature, and after maintaining the third preset temperature for a second duration, it is increased from the third preset temperature to the first preset temperature. In the first cycle phase, the humidity during the temperature maintenance phase is a first preset humidity, and the humidity during the heating and cooling phases is greater than a second preset humidity. The first preset humidity is greater than the second preset humidity. The humidity control action in the second cycle phase stops, and the first preset humidity is used as the initial humidity.

[0008] In some embodiments, the number of first cycle stages is two, the number of second cycle stages is one, and the second cycle stage follows the two first cycle stages.

[0009] In some embodiments, the number of temperature and humidity alternation cycles, N1, satisfies: 4≤N1≤10; The number of iterations N2 satisfies: 9 ≤ N2 ≤ 15.

[0010] In some embodiments, controlling the input of a plurality of sequentially increasing preset power values ​​to the power conversion device via the second input terminal includes: For each preset power, a target power is allocated to each of the second input terminals based on the preset power and the number of the second input terminals; The control inputs the target power to the power conversion device at the maximum operating voltage of the power conversion device through each of the second input terminals.

[0011] In some embodiments, each preset power P iSatisfying: 10% × P max ≤P i ≤50%×P max P max Full power.

[0012] Secondly, a condensation testing system for a power conversion device is also provided, comprising: An environmental test chamber is used to house the power conversion device and provide a controllable temperature and humidity environment. The power conversion device includes multiple power input terminals. A power supply, which is connected to each of the power input terminals via cables, is used to selectively output power to at least a portion of the power input terminals. The controller, connected to the environmental test chamber, the power supply, and the power conversion device, is used to control the power supply to configure the first input terminal of the plurality of power input terminals to a state without electrical stress and the second input terminal to a state with electrical stress, and to perform the following steps: At least one cyclic test is performed on the power conversion device; wherein the cyclic test includes a first test and a second test set sequentially; The first test includes controlling the power conversion device to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device to be switched to a power-on state, and controlling the input of a plurality of preset power values ​​that are sequentially increased to the power conversion device through the second input terminal, wherein each preset power value is less than the full power value.

[0013] In some embodiments, the power conversion device is provided with multiple measuring points, and each measuring point is provided with at least one of a water-sensitive color-changing indicator and a temperature and humidity sensor. The water-sensitive color-changing indicator is used to indicate the condensation state of the power conversion device, and the temperature and humidity sensor is used to collect the temperature and humidity inside the power conversion device to determine the dew point temperature inside the power conversion device.

[0014] In some embodiments, the first input terminal is one or both of the plurality of power input terminals.

[0015] The method in this application, by configuring one part of the power input terminal to be in a state without electrical stress while another part is in a state with electrical stress, can create a difference between the heating and cooling zones inside the power conversion equipment, thereby helping to expose the risks of weak insulation areas inside the equipment under condensation conditions. By first executing a temperature and humidity alternating cycle in the shutdown state, the equipment can fully absorb moisture and form condensation due to the breathing effect. Then, when the temperature and humidity adjustment is stopped, the power-on load stage is executed, and a preset power less than full power is sequentially input through the second input terminal. This can apply progressively increasing electric field stress before the power conversion equipment itself has fully dissipated the condensation due to heat generation, thereby helping to capture the early electrical failure window under the simultaneous action of condensation and electric field. The method as a whole, by staggering the timing of moisture absorption and condensation and stepped charging, helps to accurately simulate the actual field conditions, thereby improving the situation where the test conditions deviate greatly from the actual field conditions, and helps to improve the effectiveness of testing for reliability problems such as creepage and short circuits caused by condensation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the condensation testing system of the power conversion device according to an embodiment of this application; Figure 2 This is a schematic diagram of the overall process of the condensation test method for the power conversion device according to an embodiment of this application; Figure 3 This is a schematic diagram illustrating the temperature curve changes during a temperature and humidity alternation cycle, as shown in an embodiment of this application. Figure 4 This is a schematic diagram of a loop test according to an embodiment of this application; Figure 5 This is a schematic diagram illustrating the specific process of the condensation test method for the power conversion device according to an embodiment of this application.

[0018] Explanation of reference numerals in the attached figures: 10-Environmental test chamber; 20-Power supply; 30-Controller; 40-Power conversion device; 41-Power input terminal; 411-First input terminal; 412-Second input terminal; 50-Cable. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0021] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0022] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0023] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0024] Power conversion devices 40, such as photovoltaic inverters and energy storage converters, typically need to operate outdoors or in high-humidity environments for extended periods. When the ambient temperature drops or the air humidity increases, causing the temperature in certain areas of the power conversion device 40 to fall below the dew point temperature of the surrounding air, water vapor in the air will condense into liquid water, forming condensation. Condensation can lead to reduced electrical clearances and decreased insulation resistance, thereby causing reliability issues such as creepage and short circuits.

[0025] During outdoor operation, the power conversion equipment 40 experiences thermal expansion and contraction of the internal gases due to alternating day and night temperatures, resulting in continuous gas exchange with the high-humidity outside air. This causes moisture to accumulate inside the equipment, a process known as the "breathing effect." In practical applications, due to varying numbers of photovoltaic strings connected, partial string failures, or insufficient configuration, some power modules may operate with power and generate heat while others remain cool, creating an asymmetrical load. These special operating conditions are typically difficult to account for during condensation reliability testing of the equipment.

[0026] For the condensation reliability test of the power conversion equipment 40, it is usually carried out according to the alternating damp heat test or the standard condensation test, such as the relevant national standards of GB / T 2423 series. The test method usually involves placing the product in an environmental test chamber 10 and conducting a static test on a set high humidity environment and temperature alternating curve, or conducting a full-load operation test under constant temperature and humidity conditions.

[0027] However, this type of testing method has the following shortcomings: First, it does not fully simulate the real timing of the alternating temperature and humidity cycle and the live operating state, and cannot reproduce the water vapor intrusion process caused by the breathing effect; Second, the load damp heat test is usually accompanied by the continuous high temperature and high humidity of the environmental chamber, and the power conversion equipment 40 directly operates at full load. When fully loaded, the internal temperature of the equipment rises rapidly, which will instantly dry the condensation that has been generated, thereby masking the faults such as creepage and short circuits caused by liquid water accumulation when the equipment is started up in the early morning and runs at low power; Third, the test usually assumes that all input circuits of the equipment are in a state of equal heating, without considering the asymmetrical load conditions caused by the incomplete connection of the strings on site, which makes it impossible to effectively reproduce the cold area inside the chassis, and it is difficult to comprehensively examine the weak links of the insulation isolation area and the conformal coating protection.

[0028] In view of this, this application provides a condensation test method for a power conversion device 40. By placing part of the power input terminal 41 in a state without electrical stress and another part in a state with electrical stress, and sequentially executing a temperature and humidity alternating cycle in the shutdown state and a step-by-step increasing power load operation after stopping temperature and humidity adjustment, the timing of the condensation formation process and the electrical stress application process is staggered. This helps to accurately simulate the actual working conditions on site, improve the consistency between the test conditions and the actual working conditions on site, and thus improve the effectiveness of testing reliability problems such as creepage and short circuits caused by condensation, thereby solving at least one of the above-mentioned technical problems.

[0029] Please see Figure 1 , Figure 1 This is a schematic diagram of the condensation testing system for a power conversion device according to an embodiment of this application. The condensation testing system for the power conversion device 40 according to this embodiment includes an environmental test chamber 10, a power supply 20, and a controller 30. The environmental test chamber 10 is used to house the power conversion device 40 and provide a controllable temperature and humidity environment. The power conversion device 40 includes multiple power input terminals 41. The power supply 20 is connected to each power input terminal 41 via cables 50, and is used to selectively output power to at least a portion of the multiple power input terminals 41. The controller 30 is connected to the environmental test chamber 10, the power supply 20, and the power conversion device 40, and is used to control the power supply 20 to configure the first input terminal 411 of the multiple power input terminals 41 to a state without electrical stress and the second input terminal 412 to a state with electrical stress, and to perform the following steps: At least one cyclic test is performed on the power conversion device 40; wherein the cyclic test includes a first test and a second test set sequentially; the first test includes controlling the power conversion device 40 to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device 40 to switch to a power-on state, and controlling the input of a plurality of preset power values ​​that are sequentially increased through the second input terminal 412 to the power conversion device 40, each preset power value being less than the full power value.

[0030] Specifically, the environmental test chamber 10 is used to simulate the temperature and humidity changes experienced by the power conversion equipment 40 in an outdoor environment, such as temperature rises and falls caused by day and night cycles and high humidity environments. In this embodiment, the environmental test chamber 10 can be a walk-in high and low temperature alternating damp heat test chamber to accommodate the power conversion equipment 40 under test and provide sufficient test space, but the specific type is not limited to this, and other types can be selected according to the requirements.

[0031] Power supply 20 is used to provide electrical stress to the power input terminals 41 of the power conversion device 40. During testing, power supply 20 can selectively output power to some or all of the power input terminals 41 according to the instructions of controller 30, so as to realize the electrical stress state configuration of each power input terminal 41. Specifically, controller 30 can selectively configure some power input terminals 41 to a state without electrical stress, that is, control power supply 20 not to supply power to this part of the power input terminal 41, for example, power supply 20 output corresponding to this part of the power input terminal 41 is turned off, thereby forming a cold zone at the power module corresponding to this part of the power input terminal 41; at the same time, it configures another part of the power input terminal 41 to a state with electrical stress, that is, control power supply 20 to supply power to this part of the power input terminal 41, so that the corresponding power device is energized and generates heat, thereby forming a difference between hot and cold zones inside the power conversion device 40.

[0032] Each power input terminal 41 of the power conversion device 40 is connected to a cable 50, meaning that all power input terminals 41 are physically connected to cables. This ensures that the physical sealing of the power conversion device 40 is consistent with the actual operating conditions on site.

[0033] For example, the power source 20 can be a photovoltaic DC source or other types of DC source.

[0034] In some embodiments, the first input terminal 411 is one or two of a plurality of power input terminals 41. For example, the power input terminal 41 with the greatest impact on the surrounding environment among all power input terminals 41 can be selected as the first input terminal 411. In this way, a special topology can be artificially set where the input terminals are fully plugged in but not fully powered, creating a significant temperature difference between the internal hot and cold zones, forcing condensation to accumulate at specific unheated single-tube pins, while also maximizing the total power on the input side. By setting an asymmetrical load, the pain point of condensation in the cold zone when the photovoltaic string configuration is unbalanced can be directly addressed, and the design defects of the power conversion device 40 in terms of safety distance redundancy, three-proof coating micropores, and fan speed reduction control logic can be effectively exposed. In other embodiments, the first input terminal 411 can also be set as a preset proportion of power input terminals 41. The embodiments of this application do not specifically limit the number and position of the first input terminals 411.

[0035] In some embodiments, the power conversion device 40 is provided with multiple measuring points, each measuring point being provided with at least one of a water-sensitive color-changing indicator and a temperature and humidity sensor. The water-sensitive color-changing indicator is used to indicate the condensation state of the power conversion device 40, and the temperature and humidity sensor is used to collect the temperature and humidity inside the power conversion device 40 to determine the dew point temperature inside the power conversion device 40.

[0036] In some examples, the water-sensitive color-changing indicator can be water-sensitive color-changing paper, or other water-sensitive color-changing materials. This allows for a more intuitive and easily observable assessment of the condensation state at a given location by observing the state of the water-sensitive color-changing indicator.

[0037] For example, the temperature and humidity sensor can be a high-precision temperature and humidity probe. High-precision temperature and humidity probes are arranged around key heat-generating components (such as heat sink substrates, e.g., IGBTs) and non-heat-sensitive components (such as the pins of single tubes not connected to a photovoltaic DC source, e.g., heat sinks) inside the power conversion equipment 40 to collect temperature and humidity changes on the surface of the boost power devices not connected to a photovoltaic (PV) DC source. After grid connection and startup in the morning, the internal temperature rises, while the surface temperature of the non-heat-generating power devices is lower, resulting in a large temperature difference and high internal humidity, which leads to condensation. Water-sensitive color-changing paper is then affixed to areas prone to condensation (power devices) to monitor the dew point and actual condensation conditions of the internal microenvironment in real time.

[0038] Through the above-described scheme, the condensation test system of this application embodiment can form a difference between the heating zone and the cold zone inside the power conversion device 40, thereby helping to expose the risks of weak insulation areas inside the device under condensation environment; it can also simulate the situation where the device is fully absorbing moisture and forming condensation due to the breathing effect, and the power conversion device 40 itself has not completely dissipated the condensation due to heat generation, and apply gradually increasing electric field stress, thereby helping to capture the early electrical failure window under the simultaneous action of condensation and electric field, improving the situation where the test conditions deviate greatly from the actual field conditions, and helping to improve the test effectiveness for reliability problems such as creepage and short circuits caused by condensation.

[0039] The condensation test method of this application embodiment is described below.

[0040] Please see Figure 2 , Figure 2 This is a schematic diagram of the overall process of the condensation test method for the power conversion device according to an embodiment of this application. The power conversion device 40 is located in a controllable temperature and humidity environment. The power conversion device 40 includes multiple power input terminals 41, each of which is connected to a cable 50. The first input terminal 411 of the multiple power input terminals 41 is in a state without electrical stress, and the second input terminal 412 is in a state with electrical stress. The method specifically includes the following steps S201: Step S201: Perform at least one cyclic test on the power conversion device 40; wherein the cyclic test includes a first test and a second test set sequentially.

[0041] The first test includes controlling the power conversion device 40 to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device 40 to be switched to a power-on state, and controlling the input of multiple preset power values ​​that are sequentially increased to the power conversion device 40 through the second input terminal 412, each preset power value being less than the full power value.

[0042] Specifically, the power conversion device 40's "on" state refers to the state where the main circuit of the power conversion device 40 is energized, the internal control system is started, and it is capable of operating under load. In the "on" state, the power devices inside the power conversion device 40 can conduct, and current can flow from the power input terminal 41 to the output terminal or internal load of the power conversion device 40; the device is in an operational state and outputs power. The "off" state refers to the state where the main circuit of the power conversion device 40 is de-energized and the internal control system stops operating. In the "off" state, the power devices inside the power conversion device 40 are turned off, no current flows through the main circuit, the device does not generate output power, and it does not generate heat due to its own operation. The "no electrical stress" state refers to the state where no voltage or current is applied to the power input terminal 41, but the cable 50 of the power input terminal 41 remains physically connected; the "with electrical stress" state refers to the state where voltage is applied to the power input terminal 41 and current can be transmitted.

[0043] In the first test, the power conversion device 40 is in the off state. Although the first input terminal 411 is in a state without electrical stress and the second input terminal 412 is in a state with electrical stress, since the device is off, no current flows into the device from either power input terminal 41. No electrothermal effect is generated inside the device; only the alternating temperature and humidity cycle of the environmental test chamber 10 causes the device to absorb moisture and form condensation due to a breathing effect. In the second test, after the power conversion device 40 is switched on, electrical power is input to the device through the second input terminal 412. The first input terminal 411 remains in a state without electrical stress, thus forming a heating zone at the power device corresponding to the second input terminal 412 and a cold zone at the power device corresponding to the first input terminal 411. This configuration remains unchanged throughout the entire test process until the full-load test phase begins.

[0044] Specifically, step S201 includes the following steps S2011 to S2012: Step S2011: Control the power conversion device 40 to be in the off state, and control the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle.

[0045] Please see Figure 3 , Figure 3This is a schematic diagram illustrating the temperature curve change example of a temperature and humidity alternating cycle according to an embodiment of this application. In some embodiments, each temperature and humidity alternating cycle includes at least one first cycle stage W1 and a second cycle stage W2. In step S2011, controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle can be specifically implemented in the following ways: In each first cycle stage, the controllable temperature and humidity environment is controlled to rise from the first preset temperature T1 to the second preset temperature T2, and after maintaining the second preset temperature T2 for a first duration t1, it is lowered from the second preset temperature T2 to the first preset temperature T1. In the second cycle stage, the controllable temperature and humidity environment is controlled to decrease from the first preset temperature T1 to the third preset temperature T3, and after maintaining the third preset temperature T3 for a second duration t2, it is increased from the third preset temperature T3 to the first preset temperature T1.

[0046] In the first cycle stage, the humidity during the temperature maintenance stage is the first preset humidity, and the humidity during the heating and cooling stages is greater than the second preset humidity. The first preset humidity is greater than the second preset humidity. In the second cycle stage, the humidity control action stops, and the first preset humidity is used as the initial humidity.

[0047] For example, the first preset temperature is 25℃. The second preset temperature is 65℃. The third preset temperature is -10℃. The first duration t1 is 3.5 hours. The second duration t2 is 3 hours. The first preset humidity is 95%RH. The second preset humidity is 80%RH. The changes during the heating and cooling phases can be linear or non-linear, and are not specifically limited.

[0048] Specifically, the first cycle stage W1 corresponds to the high-temperature cycle section of the alternating damp heat test, used to simulate the humidity environment during the temperature rise and fall process when the equipment experiences diurnal temperature differences outdoors, to induce the equipment to absorb moisture due to the breathing effect. The second cycle stage W2 corresponds to the low-temperature cycle section, used to simulate the condensation conditions of the equipment in a low-temperature environment, to verify whether there is a risk of condensation in the equipment in low-temperature areas. In the first cycle stage W1, the humidity during the heating and cooling stages is set to be higher than the second preset humidity, and the humidity during the temperature maintenance stage is set to the first preset humidity. This maintains a high ambient humidity during temperature changes, allowing the equipment to fully absorb moisture, and maintains high humidity conditions after the temperature stabilizes to promote condensation formation. In the second cycle stage W2, the humidity control action stops and the initial humidity is the first preset humidity. This allows the humidity in the second cycle stage W2 to change naturally, thus simulating the gradual change of humidity in a low-temperature environment.

[0049] For example, there are two first cycle stages W1 and one second cycle stage W2, with the second cycle stage W2 following the two first cycle stages W1. That is, a complete temperature and humidity alternation cycle includes, in sequence: first cycle stage W1, second cycle stage W2, and so on. The two first cycle stages W1 are executed consecutively, and the second cycle stage W2 is executed after the two first cycle stages W1 are completed.

[0050] For example, before the start of the first cycle phase W1, the controlled temperature and humidity environment is maintained at a first preset temperature T1 for a third duration t3. Before the start of the second cycle phase W1, the controlled temperature and humidity environment is maintained at a first preset temperature T1 for a fourth duration t4. Before the start of the second cycle phase W2, the controlled temperature and humidity environment is maintained at a first preset temperature T1 for a fifth duration t5. After the end of the second cycle phase W2, the controlled temperature and humidity environment is maintained at a first preset temperature T1 for a sixth duration t6. For example, the third duration t3 is 2 hours. The fourth duration t4 is 0.5 hours. The fifth duration t5 is 2 hours. The sixth duration t6 is 1.5 hours.

[0051] It should be noted that the temperature, humidity and duration values ​​mentioned above are specific examples. In actual testing, they can be adjusted appropriately according to the type, specifications and test standards of the power conversion device 40 under test. For example, the first preset temperature T1 is not limited to 25℃, the second preset temperature T2 is not limited to 65℃, and the third preset temperature T3 is not limited to -10℃. The holding time and adjustment time of each stage can also be selected according to actual needs, as long as the alternation of temperature and humidity can be achieved to promote the formation of condensation inside the device.

[0052] For example, the temperature and humidity settings of the environmental test chamber 10 under a temperature and humidity alternation cycle are shown in Table 1. Table 1 shows the specific parameter settings of the controllable temperature and humidity environment under a temperature and humidity alternation cycle, which includes two first cycle stages and one second cycle stage.

[0053] The temperature was maintained at 25°C for two hours, during which the humidity increased from 0%RH to 95%RH. Then, the first cycle began: the temperature was increased from 25°C to 65°C, and the humidity was maintained above 80%RH for 2 hours; then the temperature was maintained at 65°C and 95%RH for 3.5 hours; then the temperature was decreased from 65°C to 25°C, and the humidity was maintained above 80%RH for 2 hours. After the first cycle, the temperature was maintained at 25°C and 95%RH for 0.5 hours.

[0054] Entering the second first cycle phase: the temperature is increased from 25℃ to 65℃, and the humidity is maintained above 80%RH for 2 hours; then, the temperature is maintained at 65℃ and the humidity at 95%RH for 3.5 hours; then, the temperature is decreased from 65℃ to 25℃, and the humidity is maintained above 80%RH for 2 hours. After the second first cycle phase ends, the temperature is maintained at 25℃ and the humidity at 95%RH for 2 hours.

[0055] Entering the second cycle stage: the temperature drops from 25℃ to -10℃, with an initial humidity of 95%RH, without any adjustment or control, for a cooling adjustment time of 0.5 hours; maintain -10℃ for 3 hours; then raise the temperature from -10℃ to 25℃, with an adjustment time of 1.5 hours. After the second cycle stage ends, maintain 25℃ and 95%RH for 1.5 hours.

[0056] Table 1: Setup of a Temperature and Humidity Alternating Cyclic Environment Test Chamber (10 settings)

[0057] In some examples, the number of temperature and humidity cycles, N1, satisfies: 4 ≤ N1 ≤ 10. For example, the number of temperature and humidity cycles, N1, is any one of 4, 5, 6, 7, 8, 9, 10, or a range of any two.

[0058] Taking the number of temperature and humidity alternation cycles N1 as 4 as an example, the power conversion device 40 can continuously perform 4 cycles of temperature and humidity alternation in the environmental test chamber 10, thereby using temperature fluctuations to generate a breathing effect, causing external water vapor to penetrate into the chamber and form deep condensation in the cold zone (the pin of the non-working single tube), while also taking into account the test duration, so as to obtain better experimental results as soon as possible.

[0059] The above solution perfectly matches the high-risk period of photovoltaic power stations reconnecting to the grid in the early morning after days of rain, effectively stimulating insulation faults that cannot be detected in a purely static high-humidity environment.

[0060] Step S2012: Control the temperature and humidity adjustment of the controllable temperature and humidity environment to stop, control the power conversion device 40 to switch to the power-on state, and control the input of multiple preset power values ​​that increase sequentially through the second input terminal 412 to the power conversion device 40, each preset power value being less than the full power value.

[0061] Specifically, after several temperature and humidity alternation cycles, the temperature and humidity alternation control of the controllable temperature and humidity environment is stopped, or the environment is maintained in a low-temperature state without humidification. The power conversion equipment 40 is powered on and put into operation under load.

[0062] In some examples, each preset power P i Satisfying: 10% × P max ≤P i≤50%×P max P max Full power. For example, preset power P i It can be set to 10%P max 20%P max 30%P max 40%P max and 50%P max The power value can be any one of the values ​​or a range of both. This range covers the area from low power to near half load, simulating the process of photovoltaic power increasing from weak to strong after sunrise. At low power, self-heating is extremely slow, insufficient to immediately dissipate condensation accumulated in the previous cycles; simultaneously, without external heat injection, the maximum voltage is already applied across the single tube, easily triggering electrochemical migration or creepage short circuits. In other words, it can simulate the gradual power increase of the equipment after startup in the morning, while avoiding direct full-load operation that would cause rapid internal heating and instantly dry the existing condensation.

[0063] For example, the preset power can be three successively increasing power values, with the difference between any two adjacent preset power values ​​being the same. For instance, the three preset power values ​​P1, P2, and P3 can be set to 10%, 30%, and 50% of the full power of the power conversion device 40, respectively.

[0064] In step S2012, 10% of the rated power, 30% of the rated power, and 50% of the rated power are sequentially input to the power conversion device 40 through the second input terminal 412. After the preset power is continuously input to the power conversion device 40 through the second input terminal 412 for a seventh time, the next preset power is input to the power conversion device 40 through the second input terminal 412. This continues until each preset power is input. For example, the seventh time can be set to 1 hour. After continuously inputting 10% of the rated power to the power conversion device 40 through the second input terminal 412 for 1 hour, then continuously inputting 30% of the rated power for 1 hour, and finally continuously inputting 50% of the rated power for 1 hour.

[0065] In some embodiments, in step S2012, controlling the input of a plurality of sequentially increasing preset power values ​​to the power conversion device 40 through the second input terminal 412 can be achieved in the following manner: For each preset power, the target power allocated to each second input terminal 412 is determined based on the preset power and the number of second input terminals 412; The control inputs the corresponding target power to the power conversion device 40 at the maximum operating voltage of the power conversion device 40 through each second input terminal 412.

[0066] For example, assuming the number of second input terminals 412 among the multiple power input terminals 41 is M (M is a positive integer), for each preset power Pi (i=1, 2, ..., n, where n is the total preset power, for example, n=3), the target power allocated to each second input terminal 412 is P. i / M.

[0067] In actual testing, to ensure that the applied electrical stress sufficiently challenges the safety distances and insulation limits inside the device under humid conditions, each second input terminal 412 inputs power to the power conversion device 40 at its maximum operating voltage. This maximum operating voltage can be, for example, 1000V or 1500V, depending on the rated voltage level of the power conversion device 40 under test. Since each second input terminal 412 applies the maximum operating voltage, different preset power levels are achieved through current adjustment, ensuring the most stringent potential difference is applied inside the device. During testing, each second input terminal 412 simultaneously inputs power to the power conversion device 40 according to its assigned target power, causing the power module corresponding to the second input terminal 412 to operate energized and generate heat, while the power module corresponding to the first input terminal 411 remains in a stress-free state, thus creating a temperature difference between hot and cold zones inside the device. As the preset power gradually increases from 10% to 50%, the heat generated by the equipment gradually increases, but the heating rate is relatively slow. The condensation accumulated in the early stage will not be dried instantly, thus providing a time window for detecting electrical failures caused by condensation.

[0068] The above scheme stops temperature and humidity intervention during the load phase and adopts stepped power. It purely utilizes the condensation accumulated in the early stage, combined with the slow heating of the equipment itself and the extreme electric field to counteract it. It accurately captures the high-risk window period of electrical failure when the condensation has not yet evaporated. It can also prevent the problem of instantaneous high temperature drying of condensation during full-load testing. It seizes the fatal time difference when the water vapor has not yet evaporated but the high voltage has been established, thereby avoiding false negatives and missed tests.

[0069] Please see Figure 4 , Figure 4 This is a schematic diagram of the cyclic test according to an embodiment of this application. In some embodiments, the number of cyclic tests N2 satisfies: 9 ≤ N2 ≤ 15. For example, the cyclic test N2 can be set to any one of 9, 10, 11, 12, 13, 14, 15, or a range of any two. Taking the cyclic test N2 set to 9 as an example, then 9 cyclic tests can be performed on the power conversion device 40, each cyclic test including 4 temperature and humidity alternating cycles and 1 stepped charged excitation operation. Finally, a total of 36 static moisture absorption cycles and 9 stepped charged excitation operations are performed. In this way, it is easier to reproduce some special high temperature and high humidity operating conditions, greatly improving the consistency between the test conditions and the actual operating conditions.

[0070] Please see Figure 5 , Figure 5This is a schematic flowchart illustrating the condensation test method for a power conversion device according to an embodiment of this application. In some embodiments, after performing step S201, the method further includes the following step S202: Step S202: Perform a full-load test on the power conversion device 40; wherein, the full-load test includes a first test and a third test set sequentially.

[0071] The third test includes stopping the temperature and humidity adjustment of the controllable temperature and humidity environment, switching the power conversion device 40 to the power-on state, switching the first input terminal 411 to the state with electrical stress, and controlling all power input terminals 41 to output full power to the power conversion device 40.

[0072] Specifically, step S202 includes the following steps S2021 to S2022: Step S2021: Control the power conversion device 40 to be in the off state, and control the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle.

[0073] For example, the specific implementation of step S2021 can be found in the description of step S2011 above, and will not be repeated here.

[0074] Step S2022: Stop the temperature and humidity adjustment of the controllable temperature and humidity environment, switch the power conversion device 40 to the power-on state, switch the first input terminal 411 to the state with electrical stress, and control all power input terminals 41 to output full power to the power conversion device 40.

[0075] For example, after completing multiple cycle tests, such as nine cycle tests, a full-load test is performed. In the full-load test, a first test is first performed, where the power conversion device 40 is controlled to be in a powered-off state, and the controllable temperature and humidity environment is controlled to run at least one temperature and humidity alternating cycle, for example, four temperature and humidity alternating cycles, so that the device absorbs moisture due to the breathing effect in the powered-off state, causing condensation to form in some areas. Then, a third test is performed, where after the first test is completed, the temperature and humidity adjustment of the controllable temperature and humidity environment is stopped, the power conversion device 40 is switched to a powered-on state, and the first input terminal 411 is switched from a state without electrical stress to a state with electrical stress, so that all power input terminals 41 have electrical stress, and all power input terminals 41 together input full power to the power conversion device 40, causing the device to operate at full-load power. At this time, the power modules corresponding to all power input terminals 41 are energized and generating heat.

[0076] The purpose of the full-load test is to verify whether the dielectric strength of the conformal coating and insulating materials of the power conversion equipment 40 has irreversibly decreased after undergoing a long-term condensation accumulation and alternating wet and dry aging process through multiple cycles of testing, and whether the equipment can still meet the insulation and safety requirements under full-load operating conditions. During the full-load test, all power input terminals 41 are switched to an electrically stressed state, and all power input terminals 41 jointly input full power to the equipment, causing the entire internal structure of the equipment to heat up, in order to test the insulation performance of the equipment after long-term condensation aging. By observing whether creepage, short circuits, or other electrical abnormalities occur during full-load operation, it can be determined whether the condensation reliability of the equipment after long-term use meets the design requirements.

[0077] The method in this application embodiment, by configuring part of the power input terminal 41 to be in a state without electrical stress while another part is in a state with electrical stress, can construct an asymmetrical load, thereby creating a difference between the heating zone and the cold zone inside the power conversion device 40, which helps to expose the risks of weak insulation areas inside the device in a condensation environment; by first executing a temperature and humidity alternating cycle in the shutdown state, the device can fully absorb moisture and form condensation due to the breathing effect, and then executing the start-up load stage when the temperature and humidity adjustment is stopped, and controlling the input of a preset power less than the full power through the second input terminal 412 in an increasing manner, can apply a gradually increasing electric field stress under the condition that the power conversion device 40 itself has not completely dissipated the condensation, thereby helping to capture the early electrical failure window under the simultaneous action of condensation and electric field. This method decouples environmental stress and electrothermal stress by staggering the timing of moisture absorption and condensation with stepped charging. This helps to accurately simulate actual field conditions, thereby improving the situation where the test conditions deviate significantly from the actual field conditions. It also helps to improve the effectiveness of testing reliability issues such as creepage and short circuits caused by condensation, and accurately fills the blind spots in test standards that are prone to missing edge failures.

[0078] This embodiment also provides a computer-readable storage medium having a computer program stored thereon, the computer program being loaded by a processor to perform the steps of any of the methods in the above embodiments.

[0079] In the embodiments of this application, the storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc.

[0080] It should be noted that, in the data processing stage, the technical solution of this application has strictly limited the scope of data collection to the minimum necessary to achieve the technical objectives, preventing the acquisition of irrelevant information. For any user information to be collected, the data subject will be clearly informed and their consent obtained. Furthermore, technologies such as encrypted storage and access control are employed to strengthen data security and ensure the security and compliance of the entire data processing process. The technical model and decision-making mechanism are based on objective technical parameters and do not introduce unnecessary parameters such as gender or age that may lead to discrimination, resolutely eliminating algorithmic discrimination and upholding public order and good morals. In addition, the specification fully describes the technical implementation methods, application scenarios, and compliance protection details. The claims are consistent with the content of the specification, key compliance designs are clear and verifiable, and the overall technical design is guided by the protection of public interests and adherence to social ethics, without any circumstances that harm public interests or violate public order and good morals.

[0081] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0082] The above provides a detailed description of a condensation testing method and system for a power conversion device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for testing condensation in a power conversion device, characterized in that, The power conversion device is located in a temperature and humidity controlled environment. The power conversion device includes multiple power input terminals, each connected to a cable. A first input terminal is in a stress-free state, and a second input terminal is in a stress-exposed state. The condensation test method includes: At least one cyclic test is performed on the power conversion device; wherein the cyclic test includes a first test and a second test set sequentially; The first test includes controlling the power conversion device to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device to be switched to a power-on state, and controlling the input of a plurality of preset power values ​​that are sequentially increased to the power conversion device through the second input terminal, wherein each preset power value is less than the full power value.

2. The condensation test method for power conversion equipment according to claim 1, characterized in that, After performing at least one cycle test on the power conversion device, the condensation test method further includes: A full-load test is performed on the power conversion device; wherein the full-load test includes a first test and a third test set sequentially. The third test includes stopping the temperature and humidity adjustment of the controllable temperature and humidity environment, switching the power conversion device to the power-on state, switching the first input terminal to the state with electrical stress, and controlling all power input terminals to output the full power to the power conversion device.

3. The condensation test method for power conversion equipment according to claim 1, characterized in that, Each of the temperature and humidity alternation cycles includes at least one first cycle stage and one second cycle stage; controlling the controllable temperature and humidity environment to operate at least one temperature and humidity alternation cycle includes: In each of the first cycle phases, the controllable temperature and humidity environment is controlled to rise from a first preset temperature to a second preset temperature, maintain the second preset temperature for a first duration, and then decrease from the second preset temperature back to the first preset temperature; In the second cycle phase, the controllable temperature and humidity environment is controlled to decrease from the first preset temperature to the third preset temperature, and after maintaining the third preset temperature for a second duration, it is increased from the third preset temperature to the first preset temperature. In the first cycle phase, the humidity during the temperature maintenance phase is a first preset humidity, and the humidity during the heating and cooling phases is greater than a second preset humidity. The first preset humidity is greater than the second preset humidity. The humidity control action in the second cycle phase stops, and the first preset humidity is used as the initial humidity.

4. The condensation test method for power conversion equipment according to claim 3, characterized in that, The number of first cycle stages is two, the number of second cycle stages is one, and the second cycle stage is located after the two first cycle stages.

5. The condensation test method for power conversion equipment according to claim 1, characterized in that, The number of temperature and humidity alternation cycles, N1, satisfies: 4≤N1≤10; The number of iterations N2 satisfies: 9 ≤ N2 ≤ 15.

6. The condensation test method for power conversion equipment according to claim 1, characterized in that, Controlling the input of a plurality of sequentially increasing preset power values ​​to the power conversion device via the second input terminal includes: For each preset power, a target power is allocated to each of the second input terminals based on the preset power and the number of the second input terminals; The control inputs the target power to the power conversion device at the maximum operating voltage of the power conversion device through each of the second input terminals.

7. The condensation test method for power conversion equipment according to claim 1, characterized in that, Each of the preset power P i Satisfying: 10% × P max ≤P i ≤50%×P max P max This refers to the full power.

8. A condensation testing system for a power conversion device, characterized in that, include: An environmental test chamber is used to house the power conversion device and provide a controllable temperature and humidity environment. The power conversion device includes multiple power input terminals. A power supply, which is connected to each of the power input terminals via cables, is used to selectively output power to at least a portion of the power input terminals. The controller, connected to the environmental test chamber, the power supply, and the power conversion device, is used to control the power supply to configure the first input terminal of the plurality of power input terminals to a state without electrical stress and the second input terminal to a state with electrical stress, and to perform the following steps: At least one cyclic test is performed on the power conversion device; wherein the cyclic test includes a first test and a second test set sequentially; The first test includes controlling the power conversion device to be in a power-off state and controlling the controllable temperature and humidity environment to run at least one temperature and humidity alternating cycle; the second test includes controlling the temperature and humidity adjustment action of the controllable temperature and humidity environment to stop, controlling the power conversion device to be switched to a power-on state, and controlling the input of a plurality of preset power values ​​that are sequentially increased to the power conversion device through the second input terminal, wherein each preset power value is less than the full power value.

9. The condensation testing system for power conversion equipment according to claim 8, characterized in that, The power conversion device is provided with multiple measuring points, and each measuring point is provided with at least one of a water-sensitive color-changing indicator and a temperature and humidity sensor. The water-sensitive color-changing indicator is used to indicate the condensation state of the power conversion device, and the temperature and humidity sensor is used to collect the temperature and humidity inside the power conversion device to determine the dew point temperature inside the power conversion device.

10. The condensation testing system for power conversion equipment according to claim 8, characterized in that, The first input terminal is one or both of the plurality of power input terminals.

Images