A wind power variable pitch system power grid fault detection method, system, terminal and medium

Abstract

The application discloses a kind of wind power variable pitch system power grid fault detection method, system, terminal and medium, it is related to wind power generation technical field, its technical scheme main point is: by obtaining three-phase line voltage value detected by pitch driver, and based on the cosine law relationship between line voltage and phase voltage Mapping relationship is established, without increasing any external hardware voltage measurement module, only using the line voltage detection capability that driver has inside, i.e. By setting upper and lower threshold and comparing with line voltage, according to the preset judgment logic, it can be identified whether there is single-phase voltage anomaly in power grid and locate abnormal phase.Cose law reveals the inherent vector relationship between line voltage and phase voltage, when a certain phase voltage drops or rises, the two line voltages containing the phase will change simultaneously, while the third line voltage remains unchanged, by comparing the relative size of the three line voltages and the threshold, the abnormal phase can be uniquely determined.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, and more specifically, to a method, system, terminal, and medium for detecting grid faults in a wind power pitch system. Background Technology

[0002] Currently, electric pitch control systems are widely used in the wind power industry. The pitch driver, as the core component of the pitch system, connects to a three-phase AC power grid at its input. Internally, it uses rectifier and inverter units to convert the AC power into the voltage and frequency required by the motor, thereby driving the AC servo motor to control the pitch of the wind turbine blades. In practical applications, pitch drivers generally use a three-phase three-wire power supply, without a neutral wire. Due to this wiring characteristic, the driver can only detect the three-phase line voltages and cannot directly detect the phase voltages relative to the neutral point. When abnormal conditions such as single-phase voltage drops or rises occur in the power grid, due to the lack of direct measurement methods for phase voltages, existing technology cannot accurately determine which phase voltage is abnormal based solely on line voltage values, nor can it distinguish the specific magnitude of voltage drops or rises. Without adding an additional hardware voltage measurement module, the pitch system cannot promptly detect single-phase abnormalities in the power grid, thus failing to take corresponding early warning and protection actions, posing a threat to the operational safety of the wind turbine.

[0003] To address the aforementioned issues, existing technologies include several power grid fault detection methods. For example, some methods detect phase loss faults by detecting line voltage imbalance or calculating phase voltage from instantaneous line voltage values. However, most of these methods can only determine the presence of extreme faults such as phase loss; they cannot identify gradual abnormal states such as continuous drops or rises in single-phase voltage, nor can they accurately pinpoint the specific phase where the abnormality occurred. Furthermore, some solutions rely on complex hardware circuits or additional sensors, increasing system cost and failure rate.

[0004] Therefore, how to accurately identify and locate a specific single-phase voltage drop or rise anomaly in the power grid using only the existing line voltage detection capability of the pitch drive without adding external hardware is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method, system, terminal, and medium for detecting grid faults in a wind power pitch system. By acquiring the three-phase line voltage values ​​detected by the pitch driver and establishing a mapping relationship based on the cosine law relationship between line voltage and phase voltage, without adding any external hardware voltage measurement modules, the present invention can identify whether there is a single-phase voltage anomaly in the grid and locate the abnormal phase by setting upper and lower threshold values ​​and comparing them with the line voltage according to a preset judgment logic, using only the existing line voltage detection capability inside the driver.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: Firstly, a method for detecting grid faults in a wind power pitch system is provided, applied to a pitch drive, comprising the following steps: The three-phase line voltage values ​​detected by the pitch drive are obtained, including the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A. Based on the cosine law relationship between line voltage and phase voltage, the mapping relationship between line voltage and phase voltage is determined, and the judgment logic is determined; wherein, under the condition that the included angle of the three phases of the power grid is equal and is 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages. Set the lower and upper threshold values ​​of the normal grid voltage that the pitch drive can withstand; The first line voltage, the second line voltage, and the third line voltage are compared with the lower threshold and the upper threshold, respectively. Based on the comparison results and in accordance with the judgment logic, identify whether there is a single-phase voltage anomaly in the power grid and locate the specific phase where the anomaly occurred.

[0007] Furthermore, the judgment logic includes: When the first line voltage, the second line voltage, and the third line voltage are all greater than the lower threshold and less than the upper threshold, the grid voltage is determined to be normal. When the first line voltage, the second line voltage, and the third line voltage are all less than the lower threshold, it is determined that the grid voltage has dropped simultaneously in two or three phases. When the first line voltage, the second line voltage, and the third line voltage are all greater than the upper limit threshold, it is determined that the grid voltage has increased simultaneously in two or three phases.

[0008] Furthermore, the judgment logic includes: When both the first line voltage and the third line voltage are less than the lower threshold, and the second line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase A of the power grid has dropped. When both the first line voltage and the second line voltage are less than the lower threshold, and the third line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase B of the power grid has dropped. When both the second line voltage and the third line voltage are less than the lower threshold, and the first line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase C of the power grid has dropped.

[0009] Furthermore, the judgment logic includes: When both the first line voltage and the third line voltage are greater than the upper limit threshold, and the second line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase A of the power grid has increased. When both the first line voltage and the second line voltage are greater than the upper limit threshold, and the third line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase B of the power grid has increased. When both the second line voltage and the third line voltage are greater than the upper limit threshold, and the first line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase C of the power grid has increased.

[0010] Furthermore, both the lower threshold and the upper threshold are configured with multiple preset values, each preset value corresponding to a phase voltage anomaly ratio; The method also includes: Based on the comparison results, when a single-phase voltage anomaly is identified, the specific preset value of the lower limit threshold or the upper limit threshold that causes the comparison results to be valid is determined, and the voltage drop or rise of the abnormal phase is obtained.

[0011] Furthermore, the preset values ​​are configured as follows: When the lower limit threshold is set to 1.56 times the effective value of the rated phase voltage, the corresponding single-phase voltage drops to 80% of the rated value. When the lower limit threshold is set to 1.32 times the rated effective value of the phase voltage, the corresponding single-phase voltage drops to 50% of the rated value. When the lower limit threshold is set to 1.00 times the effective value of the rated phase voltage, the corresponding single-phase voltage drops to 0; When the upper limit threshold is set to 1.82 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 110% of the rated value. When the upper limit threshold is set to 1.91 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 120% of the rated value. When the upper limit threshold is set to 2.00 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 130% of the rated value.

[0012] Furthermore, the method also includes: When a single-phase voltage anomaly is detected, the pitch driver issues a warning signal or performs a protective action to ensure the safety of the wind turbine.

[0013] Secondly, a grid fault detection system for a wind power pitch system is provided, comprising: The voltage acquisition module is used to acquire the three-phase line voltage values ​​detected by the pitch drive, the three-phase line voltage values ​​including the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A; The logic determination module is used to determine the mapping relationship between line voltage and phase voltage based on the cosine law relationship between line voltage and phase voltage, and to determine the judgment logic; wherein, under the condition that the included angles of the three phases of the power grid are equal and all are 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages. The threshold setting module is used to set the lower and upper threshold values ​​of the normal grid voltage that the pitch drive can withstand. A voltage comparison module is used to compare the first line voltage, the second line voltage, and the third line voltage with the lower threshold and the upper threshold, respectively. The judgment and location module is used to identify whether there is a single-phase voltage anomaly in the power grid and locate the specific phase where the anomaly occurs, based on the comparison results and the judgment logic.

[0014] Thirdly, a computer terminal is provided, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement a grid fault detection method for a wind power pitch system as described in any one of the first aspects.

[0015] Fourthly, a computer-readable medium is provided having a computer program stored thereon, the computer program being executed by a processor to implement a grid fault detection method for a wind power pitch system as described in any one of the first aspects.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention provides a grid fault detection method for wind power pitch systems. By acquiring the three-phase line voltage values ​​detected by the pitch driver and establishing a mapping relationship based on the cosine law relationship between line voltage and phase voltage, without adding any external hardware voltage measurement modules, the method utilizes only the existing line voltage detection capability within the driver to identify whether there is a single-phase voltage anomaly in the grid and locate the abnormal phase by setting upper and lower threshold values ​​and comparing them with the line voltage according to a preset judgment logic. The cosine law reveals the inherent vector relationship between line voltage and phase voltage. When a phase voltage drops or rises, the two line voltages containing that phase will change synchronously, while the third line voltage remains unchanged. By comparing the relative magnitudes of the three line voltages with the threshold values, the abnormal phase can be uniquely identified. This invention effectively solves the problem that the lack of a neutral line in a three-phase three-wire system prevents direct detection of phase voltage and necessitates additional hardware to determine single-phase anomalies, achieving cost reduction and efficiency improvement, and enhancing the safety and reliability of wind power pitch systems.

[0017] 2. This invention further defines a preset judgment logic: when all three line voltages are between the upper and lower thresholds, it is judged as normal; when all three line voltages are below the lower threshold, it is judged as a simultaneous drop in two or three phases; and when all three line voltages are above the upper threshold, it is judged as a simultaneous rise in two or three phases. This comprehensively covers three typical operating conditions: normal grid voltage, simultaneous drop in multiple phases, and simultaneous rise in multiple phases. The symmetry of the cosine law determines that when multiple phase voltages are simultaneously abnormal, all line voltages will exhibit a consistent trend. Therefore, multiple anomalies can be quickly identified through a simple full comparison, avoiding misjudgments and omissions, and providing the pitch system with a more comprehensive grid status perception capability.

[0018] 3. This invention further defines the specific judgment conditions for single-phase voltage drops and rises. It uses two line voltages simultaneously below the lower threshold while the third line voltage is normal to locate the dropping phase, and uses two line voltages simultaneously above the upper threshold while the third line voltage is normal to locate the rising phase. This allows for precise identification of which specific phase (A, B, or C) is abnormal. According to the cosine law, each line voltage is synthesized from two phase voltages. When a phase voltage is abnormal, only the two line voltages containing that phase will deviate from the normal range, while the line voltages not containing that phase remain normal. Therefore, by observing which two line voltages simultaneously exceed the limits, the abnormal phase can be uniquely identified. This invention enables the pitch system to adopt differentiated protection strategies for specific abnormal phases, improving the accuracy and efficiency of fault handling.

[0019] 4. This invention configures the lower and upper thresholds as multiple preset values, each corresponding to a specific phase voltage anomaly ratio. Based on this, the specific preset value that triggers the comparison result is determined, thereby enabling quantitative judgment of the voltage drop or rise of the abnormal phase. Using the cosine law formula, the theoretical values ​​of the line voltage corresponding to different phase voltage anomalies can be pre-calculated. These theoretical values ​​are used as thresholds. When the actual detected line voltage triggers a specific threshold, the actual deviation ratio of the phase voltage can be calculated in reverse. This invention achieves a leap from qualitative judgment to quantitative measurement, providing a data foundation for graded early warning and refined protection of pitch systems.

[0020] 5. This invention, by triggering a warning signal or executing protective actions on the pitch drive upon detecting a single-phase voltage anomaly, can promptly transmit grid fault information to the wind turbine's main control system and automatically take protective measures such as power limiting, switching to backup power, or emergency shutdown. This effectively prevents damage to the pitch drive or wind turbine safety accidents caused by grid voltage anomalies. The response mechanism is triggered immediately after anomaly identification, shortening the time delay from fault occurrence to protection action and achieving proactive protection rather than passive tolerance. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart from Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the input and output operation of the pitch driver in Embodiment 1 of the present invention; Figure 3 This is a vector relationship diagram of phase voltage and line voltage in Embodiment 1 of the present invention; Figure 4 This is a system block diagram in Embodiment 2 of the present invention. Detailed Implementation

[0022] 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 embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0023] Example 1: A method for detecting grid faults in a wind power pitch system, applied to a pitch drive, such as... Figure 1 As shown, it includes the following steps: S1: Obtain the three-phase line voltage values ​​detected by the pitch drive. The three-phase line voltage values ​​include the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A. S2: Based on the cosine law relationship between line voltage and phase voltage, determine the mapping relationship between line voltage and phase voltage, and determine the judgment logic; wherein, under the condition that the included angles of the three phases of the power grid are equal and all are 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages. S3: Set the lower and upper threshold values ​​of the normal grid voltage that the pitch drive can withstand; S4: Compare the first line voltage, the second line voltage, and the third line voltage with the lower threshold and the upper threshold, respectively; S5: Based on the comparison results and according to the judgment logic, identify whether there is a single-phase voltage anomaly in the power grid and locate the specific phase where the anomaly occurred.

[0024] In step S1, the three-phase line voltage values ​​detected by the pitch drive are acquired. The three-phase line voltage values ​​include the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A.

[0025] Specifically, such as Figure 2 As shown, the input of the pitch drive is connected to a three-phase AC power grid, with phases A, B, and C. Internally, the drive uses a rectifier and inverter unit to output AC power with the required voltage and frequency for the motor, driving the AC servo motor. Because the pitch drive uses a three-phase three-wire power supply with no neutral wire, it can only detect the line voltage of the power grid and cannot directly detect the phase voltage.

[0026] The pitch drive incorporates a voltage detection circuit that samples the instantaneous or effective values ​​of the three-phase line voltages in real time. Let the line voltage between phase A and phase B be the first line voltage, denoted as . The line voltage between phase B and phase C is the second line voltage, denoted as . The line voltage between phase C and phase A is the third line voltage, denoted as . These three line voltage values ​​are known quantities and can be read directly from the driver's detection port.

[0027] Because the pitch drive uses a three-phase three-wire connection without a neutral wire, it is impossible to directly measure the phase voltage of each phase to the neutral point as in a three-phase four-wire system. In other words, the phase voltage of phase A... Phase B voltage C-phase voltage This is an unknown quantity relative to the pitch system. The present invention utilizes three known line voltage values ​​to indirectly determine the state of each phase voltage through subsequent steps.

[0028] In this embodiment, line voltage detection can employ existing AC voltage sampling techniques, such as converting a high-voltage AC signal into a low-voltage signal using a voltage transformer or resistive voltage divider network, and then converting it into a digital signal for processing by the controller. The detected line voltage value can be an instantaneous value or a steady-state value after filtering and RMS calculation. For ease of subsequent comparison and judgment, the RMS value is typically used as the detection result.

[0029] In step S2, based on the cosine law relationship between line voltage and phase voltage, the mapping relationship between line voltage and phase voltage is determined, and the judgment logic is determined.

[0030] In a three-phase AC power grid system, there is a fixed mathematical relationship between line voltage and phase voltage, such as... Figure 3 As shown, according to the law of cosines, under the condition that the included angles of the three phases of the power grid are equal and all are 120°, the cosine 120° equals -0.5. The square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages.

[0031] Let the angle between phase A and phase B be . The angle between phase B and phase C is The angle between phase C and phase A is Under normal grid operation and three-phase balance, the three-phase voltages differ in phase by 120°, i.e. , , Both are equal to 120 degrees. Based on the cosine law relationship between line voltage and phase voltage, the following three formulas are satisfied: ; ; .

[0032] Based on this principle, the following three formulas are simplified: The first formula is: ; The second formula is: ; The third formula is: .

[0033] Using the three formulas above, three known line voltages were established. , , With three unknown phase voltages , , The mapping relationship between them. Although it is impossible to directly solve for the specific value of each phase voltage, abnormal conditions of phase voltage can be inferred from the relative magnitude relationship between the line voltages.

[0034] Next, based on the above mapping relationship and the normal grid voltage range that the pitch drive can withstand, the preset judgment logic is determined. First, a lower threshold value for the normal grid voltage that the pitch drive can withstand is set. and upper limit threshold Among them, the lower limit threshold Indicates the minimum allowable line voltage value, upper limit threshold. This indicates the maximum permissible line voltage value. When the line voltage is at... and When the line voltage is within a certain range, the two-phase voltages corresponding to that line voltage are considered to be within the normal range.

[0035] Based on the mathematical properties of the cosine law formula, the following judgment logic can be derived: The first type of judgment logic is used to determine whether the grid voltage is normal or multiple simultaneous anomalies have occurred. When the first line voltage... Second line voltage and third line voltage All are greater than the lower threshold. And all are less than the upper limit threshold. When the first line voltage is within the normal range, it indicates that all three line voltages are within the normal range, thus indicating that the grid voltage is normal. Second line voltage and third line voltage All are less than the lower threshold. When the voltage drops to a certain level, it indicates that all line voltages are below the normal lower limit, suggesting a simultaneous voltage drop in two or three phases of the grid. When the first line voltage... Second line voltage and third line voltage All are greater than the upper limit threshold When the voltage is above the normal upper limit, it indicates that all line voltages are above the normal upper limit, and it can be determined that the grid voltage has increased simultaneously in two or three phases.

[0036] The second type of judgment logic is used to locate the specific phase where a single-phase voltage drop occurs. When the first line voltage... and third line voltage All are less than the lower threshold. And the second line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the first line voltage Involving phases A and B, third line voltage This involves phases C and A, where both line voltages are simultaneously low, while the second line voltage... This indicates a voltage drop in phase A, which is shared by both phases, while phases B and C are normal. Therefore, it is determined that the voltage drop in phase A of the power grid has occurred. When the first line voltage... Second line voltage All are less than the lower threshold. And the third line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the first line voltage Involving phases A and B, second line voltage This involves phases B and C, where both line voltages are simultaneously low, while the third line voltage... This is normal, indicating a voltage drop in the shared B-phase voltage; therefore, it is determined that a voltage drop in the B-phase of the power grid has occurred. When the second line voltage... and third line voltage All are less than the lower threshold. And the first line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the second line voltage Involving phases B and C, third line voltage This involves phases C and A, where both line voltages are simultaneously low while the first line voltage... This is normal, indicating that the voltage of the shared C-phase has dropped, therefore it is determined that the voltage of the C-phase in the power grid has dropped.

[0037] The third type of judgment logic is used to locate the specific phase where the single-phase voltage rises. When the first line voltage... and third line voltage All are greater than the upper limit threshold And the second line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the first line voltage Involving phases A and B, third line voltage This involves phases C and A, where both line voltages are simultaneously elevated, while the second line voltage... This is normal, indicating that the voltage of phase A, which is shared by both phases, has increased, while the voltages of phases B and C are normal. Therefore, it is determined that the voltage of phase A in the power grid has increased. When the first line voltage... Second line voltage All are greater than the upper limit threshold And the third line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the first line voltage Involving phases A and B, second line voltage This involves phases B and C, where both line voltages are simultaneously elevated, while the third line voltage... This is normal, indicating that the voltage of phase B, which is shared by both phases, has increased. Therefore, it is determined that the voltage of phase B in the power grid has increased. When the second line voltage... and third line voltage All are greater than the upper limit threshold And the first line voltage Greater than the lower threshold and less than the upper limit threshold At that time, due to the second line voltage Involving phases B and C, third line voltage This involves phases C and A, where both line voltages are simultaneously elevated while the first line voltage... This is normal, indicating that the voltage of the shared C-phase has increased, therefore it is determined that the voltage of the C-phase in the power grid has increased.

[0038] In step S3, the rated phase voltage is assumed to be... This rated value refers to the effective value of the voltage per phase of the power grid under standard operating conditions, measured in volts. To achieve quantitative judgment of the degree of single-phase voltage anomalies, a lower limit threshold is set. and upper limit threshold Each is configured with multiple preset values. Each preset value corresponds to a specific phase voltage anomaly ratio, meaning that the preset value indicates the specific percentage by which a phase voltage drops or rises to its rated value. These preset values ​​are calculated using the cosine law formula established in step S2 above. Specifically, according to the formula... And two other similar formulas can be used to calculate the theoretical value of the corresponding line voltage when the phase voltage changes to different degrees, and to calculate the three-phase voltage and line voltage relative to the rated phase voltage. The calculated ratios are shown in Table 1. Using these theoretical values ​​as thresholds, the abnormal amplitude of the phase voltage can be determined in reverse.

[0039] Table 1. Ratio Calculation Results

[0040] In this embodiment, the preset values ​​include the following six cases.

[0041] The first scenario is when the lower limit threshold is reached. Set to phase voltage rating At 1.56 times, that is This preset value corresponds to a single-phase voltage drop to 80% of the rated value. In other words, when both line voltages are detected to be simultaneously below 1.56 times the rated value... When the third line voltage is normal, it can be determined that the phase voltage shared by the two line voltages has dropped to 80% of the rated value.

[0042] The second scenario is when the lower limit threshold is reached. Set to phase voltage rating When it is 1.32 times, that is This preset value corresponds to a single-phase voltage drop to 50% of the rated value. At this point, if the two line voltages are less than 1.32 times the rated value... If the third line voltage is normal, it means that the corresponding phase voltage has dropped to 50% of the rated value.

[0043] The third scenario is when the lower limit threshold is reached. Set to phase voltage rating When it is 1.00 times, that is This preset value corresponds to a single-phase voltage dropping to 0. At this point, if the two line voltages are below 1.00 times... If the third line voltage is normal, it indicates that the corresponding phase voltage is completely missing, that is, the voltage drops to zero.

[0044] The fourth scenario is when the upper limit threshold is reached. Set to phase voltage rating When it is 1.82 times, that is This preset value corresponds to a single-phase voltage rising to 110% of the rated value. When two line voltages are detected simultaneously exceeding 1.82 times the rated value... When the third line voltage is normal, it can be determined that the corresponding phase voltage has risen to 110% of the rated value.

[0045] The fifth scenario is when the upper limit threshold is reached. Set to phase voltage rating When it is 1.91 times, that is This preset value corresponds to a single-phase voltage rising to 120% of the rated value. When two line voltages are detected simultaneously exceeding 1.91 times... When the third line voltage is normal, it can be determined that the corresponding phase voltage has increased to 120% of the rated value.

[0046] The sixth case is when the upper limit threshold is reached. Set to phase voltage rating When it is 2.00 times, that is This preset value corresponds to a single-phase voltage rising to 130% of the rated value. This occurs when both line voltages are simultaneously detected to be higher than 2.00 times the rated value. When the third line voltage is normal, it can be determined that the corresponding phase voltage has risen to 130% of the rated value.

[0047] The six preset values ​​mentioned above are merely exemplary values. In practical applications, other different values ​​can be set according to the specific tolerance and safety requirements of the pitch drive. and This invention uses multiple preset threshold values ​​to identify various grid voltage anomalies. By setting these thresholds, it can not only determine which phase voltage is abnormal, but also further quantify the degree of the anomaly, providing a tiered early warning and protection basis for the pitch system.

[0048] In step S4, firstly, the first line voltage obtained in step S1 is... Second line voltage and third line voltage Each is compared with the lower threshold set in step S3. and upper limit threshold A one-to-one comparison is performed. The purpose of the comparison is to determine whether each line voltage is below the lower threshold. Between and Between, or above the upper limit threshold The comparison result will trigger the preset judgment logic determined in step S2, thereby identifying whether there is a single-phase voltage anomaly in the power grid and locating the specific phase where the anomaly occurred.

[0049] When a single-phase voltage anomaly is identified based on the judgment logic in step S2, the specific preset threshold that causes the comparison result to be valid is further determined, thereby obtaining the voltage drop or rise magnitude of the abnormal phase. Since the lower limit threshold has already been set in step S3... and upper limit threshold The system can be configured with multiple preset values, each corresponding to a specific phase voltage anomaly ratio. Therefore, the degree of phase voltage anomaly can be inferred by comparing the actual triggered threshold values ​​in the results.

[0050] Specifically, when a voltage drop in a certain phase is detected, the lower threshold value that actually takes effect in the comparison results is... The preset value determines the magnitude of the drop. For example, if the lower threshold of the judgment logic is triggered during the comparison process... Exactly equal to the phase voltage rating If the voltage is 1.56 times the rated value, it indicates that the phase voltage has dropped to 80% of the rated value. If the lower threshold triggers... equals 1.32 times This indicates that the phase voltage has dropped to 50% of its rated value. If the lower threshold triggers... equal to 1.00 times If the voltage of that phase has dropped to 0, it means that the phase voltage is completely missing.

[0051] Similarly, when an increase in voltage in a certain phase is detected, the upper limit threshold of the actual effective value in the comparison results is... The preset value determines the magnitude of the increase. If the upper limit threshold is triggered... equals 1.82 times This indicates that the phase voltage has risen to 110% of the rated value. If the upper limit threshold for triggering is reached... equals 1.91 times This indicates that the phase voltage has risen to 120% of its rated value. If the upper limit threshold for triggering is reached... Equal to 2.00 times This indicates that the phase voltage has increased to 130% of the rated value.

[0052] The above six preset values ​​and their corresponding abnormal ratios are calculated based on the cosine law formula established in step S2. Taking single-phase voltage drop as an example, when the voltage of phase A... Falling to rated value 80% of The voltages of phases B and C remain constant. At that time, according to the formula It can be calculated Approximately Similarly Also approximately ,and Keep as Therefore, Set as This allows for the identification of 80% of drops. The calculation principle for other preset values ​​is similar.

[0053] Through the comparison and quantitative judgment in step S4, the present invention can not only accurately locate the abnormal phase, but also quantify the degree of the abnormality, providing a basis for graded early warning and differentiated protection for the pitch system.

[0054] In step S5, the first line voltage has been set in step S4. Second line voltage and third line voltage respectively with the lower threshold and upper limit threshold A comparison was made to determine the interval state of each line voltage. Based on the judgment logic determined in step S2, this step comprehensively judges these comparison results to identify whether there is a single-phase voltage anomaly in the power grid and to locate the specific phase where the anomaly occurred.

[0055] Through the above-described judgment logic, this invention can accurately identify a specific single-phase voltage drop or rise anomaly in the power grid and precisely locate the abnormal phase by utilizing only the existing line voltage detection capability of the pitch driver without adding any external hardware voltage measurement modules.

[0056] In some optional examples, when a single-phase voltage anomaly is detected, the pitch drive issues a warning signal or executes protective actions to ensure the safety of the wind turbine. Specifically, after completing anomaly identification and location, the pitch drive controller takes corresponding measures according to a preset safety strategy. The warning signal can be sent to the wind turbine's main control system via the drive's communication interface, prompting maintenance personnel to handle the situation promptly. Protective actions may include, but are not limited to, limiting the operating power of the pitch system, switching to backup power mode, or directly triggering an emergency shutdown to prevent damage to the pitch drive or wind turbine safety accidents caused by grid voltage anomalies. In this way, this method achieves early warning and proactive protection against grid faults, significantly improving the operational reliability of wind turbines under harsh grid conditions.

[0057] Example 2: A grid fault detection system for a wind power pitch system, which implements a grid fault detection method for a wind power pitch system described in Example 1, such as... Figure 4 As shown, it includes a voltage acquisition module, a logic determination module, a threshold setting module, a voltage comparison module, and a judgment and positioning module.

[0058] The system includes the following modules: a voltage acquisition module for acquiring the three-phase line voltage values ​​detected by the pitch drive, including the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A; a logic determination module for determining the mapping relationship between line voltage and phase voltage based on the cosine law relationship between line voltage and phase voltage, and determining the judgment logic; wherein, under the condition that the angle between the three phases of the power grid is equal and all are 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages; a threshold setting module for setting the lower and upper limits of the normal power grid voltage that the pitch drive can withstand; a voltage comparison module for comparing the first, second, and third line voltages with the lower and upper limits, respectively; and a judgment and location module for identifying whether there is a single-phase voltage anomaly in the power grid and locating the specific phase where the anomaly occurs, based on the comparison results and the judgment logic.

[0059] Example 3: A computer terminal includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a grid fault detection method for a wind power pitch system as described in Example 1.

[0060] Example 4: A computer-readable medium having a computer program stored thereon, the computer program being executed by a processor to implement a grid fault detection method for a wind power pitch system as described in Example 1.

[0061] Working Principle: This invention acquires the three-phase line voltage values ​​detected by the pitch driver and establishes a mapping relationship based on the cosine law relationship between line voltage and phase voltage. Without adding any external hardware voltage measurement modules, it utilizes only the existing line voltage detection capability within the driver to identify whether there is a single-phase voltage anomaly in the power grid and locate the abnormal phase by setting upper and lower threshold values ​​and comparing them with the line voltage according to a preset judgment logic. The cosine law reveals the inherent vector relationship between line voltage and phase voltage. When a phase voltage drops or rises, the two line voltages containing that phase will change synchronously, while the third line voltage remains unchanged. By comparing the relative magnitudes of the three line voltages with the threshold values, the abnormal phase can be uniquely identified. This invention effectively solves the problem that the lack of a neutral wire in a three-phase three-wire system prevents direct detection of phase voltage and necessitates additional hardware to determine single-phase anomalies, achieving cost reduction and efficiency improvement, and enhancing the safety and reliability of the wind power pitch system.

[0062] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0063] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0064] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0065] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0066] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for detecting grid faults in a wind power pitch control system, characterized in that, For application in pitch drives, the following steps are included: The three-phase line voltage values ​​detected by the pitch drive are obtained, including the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A. Based on the cosine law relationship between line voltage and phase voltage, the mapping relationship between line voltage and phase voltage is determined, and the judgment logic is determined; wherein, under the condition that the included angle of the three phases of the power grid is equal and is 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages. Set the lower and upper threshold values ​​of the normal grid voltage that the pitch drive can withstand; The first line voltage, the second line voltage, and the third line voltage are compared with the lower threshold and the upper threshold, respectively. Based on the comparison results and in accordance with the judgment logic, identify whether there is a single-phase voltage anomaly in the power grid and locate the specific phase where the anomaly occurred.

2. The method for detecting grid faults in a wind power pitch control system according to claim 1, characterized in that, The judgment logic includes: When the first line voltage, the second line voltage, and the third line voltage are all greater than the lower threshold and less than the upper threshold, the grid voltage is determined to be normal. When the first line voltage, the second line voltage, and the third line voltage are all less than the lower threshold, it is determined that the grid voltage has dropped simultaneously in two or three phases. When the first line voltage, the second line voltage, and the third line voltage are all greater than the upper limit threshold, it is determined that the grid voltage has increased simultaneously in two or three phases.

3. The method for detecting grid faults in a wind power pitch control system according to claim 1, characterized in that, The judgment logic includes: When both the first line voltage and the third line voltage are less than the lower threshold, and the second line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase A of the power grid has dropped. When both the first line voltage and the second line voltage are less than the lower threshold, and the third line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase B of the power grid has dropped. When both the second line voltage and the third line voltage are less than the lower threshold, and the first line voltage is greater than the lower threshold but less than the upper threshold, it is determined that the voltage of phase C of the power grid has dropped.

4. The method for detecting grid faults in a wind power pitch control system according to claim 1, characterized in that, The judgment logic includes: When both the first line voltage and the third line voltage are greater than the upper limit threshold, and the second line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase A of the power grid has increased. When both the first line voltage and the second line voltage are greater than the upper limit threshold, and the third line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase B of the power grid has increased. When both the second line voltage and the third line voltage are greater than the upper limit threshold, and the first line voltage is greater than the lower limit threshold but less than the upper limit threshold, it is determined that the voltage of phase C of the power grid has increased.

5. The method for detecting grid faults in a wind power pitch control system according to claim 1, characterized in that, Both the lower threshold and the upper threshold are configured with multiple preset values, and each preset value corresponds to a phase voltage anomaly ratio. The method also includes: Based on the comparison results, when a single-phase voltage anomaly is identified, the specific preset value of the lower limit threshold or the upper limit threshold that causes the comparison results to be valid is determined, and the voltage drop or rise of the abnormal phase is obtained.

6. The method for detecting grid faults in a wind power pitch control system according to claim 5, characterized in that, The preset values ​​are configured as follows: When the lower limit threshold is set to 1.56 times the effective value of the rated phase voltage, the corresponding single-phase voltage drops to 80% of the rated value. When the lower limit threshold is set to 1.32 times the rated effective value of the phase voltage, the corresponding single-phase voltage drops to 50% of the rated value. When the lower limit threshold is set to 1.00 times the effective value of the rated phase voltage, the corresponding single-phase voltage drops to 0; When the upper limit threshold is set to 1.82 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 110% of the rated value. When the upper limit threshold is set to 1.91 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 120% of the rated value. When the upper limit threshold is set to 2.00 times the rated effective value of the phase voltage, the corresponding single-phase voltage rises to 130% of the rated value.

7. A method for detecting grid faults in a wind power pitch control system according to any one of claims 1-6, characterized in that, The method also includes: When a single-phase voltage anomaly is detected, the pitch driver issues a warning signal or performs a protective action to ensure the safety of the wind turbine.

8. A power grid fault detection system for a wind power pitch system, characterized in that, include: The voltage acquisition module is used to acquire the three-phase line voltage values ​​detected by the pitch drive, the three-phase line voltage values ​​including the first line voltage between phase A and phase B, the second line voltage between phase B and phase C, and the third line voltage between phase C and phase A; The logic determination module is used to determine the mapping relationship between line voltage and phase voltage based on the cosine law relationship between line voltage and phase voltage, and to determine the judgment logic; wherein, under the condition that the included angles of the three phases of the power grid are equal and all are 120°, the cosine law relationship is that the square of any line voltage is equal to the sum of the squares of the corresponding two phase voltages plus the product of the corresponding two phase voltages. The threshold setting module is used to set the lower and upper threshold values ​​of the normal grid voltage that the pitch drive can withstand. A voltage comparison module is used to compare the first line voltage, the second line voltage, and the third line voltage with the lower threshold and the upper threshold, respectively. The judgment and location module is used to identify whether there is a single-phase voltage anomaly in the power grid according to the comparison result and the judgment logic, and to locate the specific phase where the anomaly occurred.

9. A computer terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements a grid fault detection method for a wind power pitch system as described in any one of claims 1-7.

10. A computer-readable medium having a computer program stored thereon, characterized in that, The computer program, when executed by a processor, can implement a grid fault detection method for a wind power pitch system as described in any one of claims 1-7.

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