Three-phase overvoltage or undervoltage rapid detection method and terminal

Abstract

The invention discloses a three-phase overvoltage or undervoltage rapid detection method and a terminal. A first positive sequence voltage amplitude and a first negative sequence voltage amplitude of target equipment are obtained through estimation by a sliding window average filtering detection method based on synchronous rotation coordinate transformation; calling a variable-parameter sliding window zero-pole matcher to correct the first positive sequence voltage amplitude and the first negative sequence voltage amplitude to obtain a second positive sequence voltage amplitude and a second negative sequence voltage amplitude; calling a fixed-parameter sliding window median filter to respectively carry out median filtering on the second positive sequence voltage amplitude and the second negative sequence voltage amplitude to obtain a third positive sequence voltage amplitude and a third negative sequence voltage amplitude; and judging whether the third positive sequence voltage amplitude and the third negative sequence voltage amplitude meet a preset overvoltage condition or a preset undervoltage condition, and if yes, outputting that the three-phase voltage of the target equipment is abnormal. According to the method, the defects of low detection speed and insufficient dynamic response in the prior art are overcome, and the rapid response requirement of voltage anomaly detection is met.

Description

Technical Field

[0001] The present invention relates to the technical field of power detection, and particularly relates to a method and a terminal for quickly detecting three-phase overvoltage or undervoltage. Background Art

[0002] In modern power systems, with the continuous increase in the access ratio of new energy power generation systems such as photovoltaic and wind power, and the increasing requirements of industries and sensitive loads for power quality, the voltage stability of the power grid is facing huge challenges. Especially when events such as voltage fluctuations, overvoltage or undervoltage occur, how to quickly and accurately detect the grid voltage and achieve voltage support has become a key issue for ensuring the stable operation of the power grid and the safety of equipment.

[0003] The problems of undervoltage and overvoltage in the power grid are usually caused by the following reasons: 1. Grid faults: Short circuits, equipment failures, etc. can cause undervoltage events; 2. Excessive reactive power compensation: Improper switching of capacitor banks or adjustment of reactive power compensation equipment may cause overvoltage events; 3. New energy fluctuations: The uncertainty of the output power of photovoltaic, wind power, etc. makes the grid voltage fluctuate more frequently; 4. Load changes: Starting or sudden disconnection of high-power loads causes undervoltage / overvoltage problems in the power grid.

[0004] To address the above problems, new energy power generation systems and flexible power quality equipment (such as dynamic voltage restorer DVR, unified power quality controller UPQC, uninterruptible power supply UPS, etc.) are all endowed with important voltage support functions to ensure the stability of the power grid or load under abnormal voltage conditions.

[0005] Currently, the sliding window average filtering detection method based on synchronous rotating coordinate transformation is an embedded voltage detection technology widely used in power equipment, and its structure is as Figure 1 shown. This method has a certain anti-interference ability, is suitable for use in complex grid environments with harmonics or noise, and has high detection accuracy under steady state. However, this method also has the following deficiencies: The recognition speed is slow, and it usually takes 3 - 5 ms to complete the judgment of over / undervoltage; The convergence speed is slow, and it takes at least half a power frequency cycle (10 ms) to complete the signal convergence. The lack of dynamic performance makes this method difficult to meet the requirements of new energy power generation systems and flexible power quality equipment for millisecond-level voltage support response in scenarios of rapid voltage dips or instantaneous overvoltage.

[0006] Therefore, researching a fast detection method for three-phase over / undervoltage with high dynamic performance is not only of great significance for improving the performance of power equipment, but also has significant engineering application value. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: to provide a three-phase overvoltage or undervoltage rapid detection method and terminal, overcome the defects of slow detection speed and insufficient dynamic response in the prior art, and meet the rapid response requirements of new energy power generation systems and flexible power quality equipment for voltage abnormality detection.

[0008] To solve the above technical problem, the technical solution adopted by the present invention is: A three-phase overvoltage or undervoltage rapid detection method, comprising the following steps: S1. Estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device through a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2. Call a variable-parameter sliding window zero-pole matcher to correct the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude respectively to obtain a second positive-sequence voltage amplitude and a second negative-sequence voltage amplitude; S3. Call a fixed-parameter sliding window median filter to perform median filtering on the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude respectively to obtain a third positive-sequence voltage amplitude and a third negative-sequence voltage amplitude; S4. Determine whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

[0009] To solve the above technical problem, another technical solution adopted by the present invention is: A three-phase overvoltage or undervoltage rapid detection terminal, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the following steps are implemented: S1. Estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device through a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2. Call a variable-parameter sliding window zero-pole matcher to correct the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude respectively to obtain a second positive-sequence voltage amplitude and a second negative-sequence voltage amplitude; S3. Call a fixed-parameter sliding window median filter to perform median filtering on the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude respectively to obtain a third positive-sequence voltage amplitude and a third negative-sequence voltage amplitude; S4. Determine whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

[0010] The beneficial effects of the present invention are as follows: A three-phase overvoltage or undervoltage rapid detection method and terminal are provided. By using the existing sliding window average filtering detection method based on synchronous rotating coordinate transformation, the first positive sequence voltage amplitude and the first negative sequence voltage amplitude of the target device are estimated. Then, the first positive sequence voltage amplitude and the first negative sequence voltage amplitude are corrected and median filtered respectively to obtain the third positive sequence voltage amplitude and the third negative sequence voltage amplitude. Combining with the preset overvoltage condition or preset undervoltage condition, the three-phase voltage abnormality detection is completed. During this period, a variable parameter sliding window zero-pole matcher and a fixed parameter sliding window median filter are introduced successively, which improves the detection speed and dynamic performance, effectively avoids the pulse noise introduced by the matcher, enhances the anti-interference ability and robustness, overcomes the defects of slow detection speed and insufficient dynamic response in the prior art, and meets the rapid response requirements of the new energy power generation system and flexible power quality equipment for voltage abnormality detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is the control block diagram of an existing three-phase overvoltage detection technology; Figure 2 is the step schematic diagram of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 3 is the control block diagram of an improved three-phase over / undervoltage rapid detection method of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 4 is the z-domain zero-pole distribution diagram of zero-pole matchers with different matching degrees of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 5 is the step response schematic diagram of zero-pole matchers with different matching degrees of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 6 is the curve schematic diagram of the positive sequence parameter adaptive adjustment rule of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 7 is the curve schematic diagram of the negative sequence parameter adaptive adjustment rule of a three-phase overvoltage or undervoltage rapid detection method of the present invention; Figure 8 is the waveform schematic diagram of a three-phase overvoltage or undervoltage rapid detection method of the present invention under the condition of three-phase power grid symmetric voltage sag; Figure 9 is the waveform schematic diagram of a three-phase overvoltage or undervoltage rapid detection method of the present invention under the condition of three-phase power grid asymmetric voltage swell (including 5th and 7th harmonics); Figure 10 is the system block diagram of a three-phase overvoltage or undervoltage rapid detection terminal of the present invention.

[0012] Label description: 1. A three-phase overvoltage or undervoltage rapid detection terminal; 2. A memory; 3. A processor. Specific implementation method

[0013] To describe the technical content, achieved objectives and effects of the present invention in detail, the following is described in conjunction with the implementation methods and accompanied by drawings.

[0014] Please refer to Figures 2 to 9 , a three-phase overvoltage or undervoltage rapid detection method, including the following steps: S1. Estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device through a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2. Call a variable parameter sliding window zero-pole matcher to correct the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude respectively, and obtain the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude; S3. Call a fixed parameter sliding window median filter to perform median filtering on the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude respectively, and obtain the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude; S4. Judge whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

[0015] As can be seen from the above description, the beneficial effects of the present invention are as follows: Use the existing sliding window average filtering detection method based on synchronous rotating coordinate transformation to estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device, and successively correct and perform median filtering on the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude to obtain the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude, and complete the three-phase voltage abnormality detection in combination with the preset overvoltage condition or the preset undervoltage condition. During this period, a variable parameter sliding window zero-pole matcher and a fixed parameter sliding window median filter are introduced successively, which improves the detection speed and dynamic performance, effectively avoids the pulse noise introduced by the matcher, enhances the anti-interference ability and robustness, overcomes the defects of slow detection speed and insufficient dynamic response in the prior art, and meets the rapid response requirements of the new energy power generation system and flexible power quality equipment for voltage abnormality detection.

[0016] Further, before step S2, it also includes: Sample and hold the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude, and adjust the matching coefficient of the variable parameter sliding window zero-pole matcher according to the sampled voltage estimate amplitude, so that the variable parameter sliding window zero-pole matcher enters the preset strong matching mode or the preset weak matching mode.

[0017] As can be seen from the above description, on the variable-parameter sliding window zero-pole matcher, according to the sampling results of the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude, the matching coefficient of the variable-parameter sliding window zero-pole matcher is adjusted to adaptively and dynamically adjust the variable-parameter sliding window zero-pole matcher to enter the preset strong matching mode or the preset weak matching mode, achieving the balance between dynamic and steady-state performance, being able to quickly identify voltage anomalies and ensuring the convergence accuracy.

[0018] Further, before the step S2, it also includes: Setting the adjustment rule of the matching coefficient, and its expression is as follows: ; where k represents the discrete-time variable, μ(k) represents the matching coefficient, μ H is the high matching coefficient, μ L is the low matching coefficient, U H is the overvoltage threshold, U L is the undervoltage threshold, U N is the rated voltage value, represents the estimated amplitude of the sampled voltage.

[0019] As can be seen from the above description, by setting the adjustment rule, when the estimated amplitude of the sampled voltage is near the rated voltage, it is adjusted to the preset strong matching mode to accelerate the detection speed; when the estimated amplitude of the sampled voltage is far from the rated voltage, it is adjusted to the preset weak matching mode to improve the detection accuracy; through the dynamic stepless adjustment of the strong / weak matching mode, the rapid identification and precise convergence in the initial stage of voltage anomalies are achieved.

[0020] Further, the step 3 includes: S31. Creating a voltage anomaly flag bit Flag for judging whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition, and its expression is as follows: ; where, represents the third positive-sequence voltage amplitude, represents the third negative-sequence voltage amplitude, represents the positive-sequence undervoltage threshold, represents the positive-sequence overvoltage threshold, represents the negative-sequence overvoltage threshold; S32. Judging whether to output the three-phase voltage anomaly of the target device according to the state of the voltage anomaly flag bit.

[0021] As can be seen from the above description, through the voltage anomaly flag bit as the judgment output result of various preset overvoltage conditions or preset undervoltage conditions, it accurately and quickly identifies whether the three-phase voltage of the target device is abnormal.

[0022] Further, the sampling and holding of the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude are specifically as follows: Sampling and holding the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude according to a preset sampling interval, and its expression is as follows: ; Wherein, represents the first positive-sequence voltage amplitude or the first negative-sequence voltage amplitude, M represents the preset sampling interval, represents the floor function.

[0023] As can be seen from the above description, the floor function is introduced, and the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude are sampled and held according to the preset sampling interval to obtain a suitable sampled voltage estimated amplitude.

[0024] Please refer to Figure 10 , a three-phase overvoltage or undervoltage rapid detection terminal 1, including a memory 2, a processor 3, and a computer program stored on the memory 2 and operable on the processor 3. When the processor 3 executes the computer program, the following steps are implemented: S1. Estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device through a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2. Call a variable-parameter sliding window zero-pole matcher to correct the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude respectively to obtain a second positive-sequence voltage amplitude and a second negative-sequence voltage amplitude; S3. Call a fixed-parameter sliding window median filter to perform median filtering on the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude respectively to obtain a third positive-sequence voltage amplitude and a third negative-sequence voltage amplitude; S4. Determine whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

[0025] As can be seen from the above description, the beneficial effects of the present invention are as follows: By using the existing sliding window average filtering detection method based on synchronous rotation coordinate transformation, the first positive sequence voltage amplitude and the first negative sequence voltage amplitude of the target device are estimated. Then, the first positive sequence voltage amplitude and the first negative sequence voltage amplitude are corrected and median filtered respectively to obtain the third positive sequence voltage amplitude and the third negative sequence voltage amplitude. Combining with the preset overvoltage condition or the preset undervoltage condition, the three-phase voltage anomaly detection is completed. During this period, a variable parameter sliding window zero-pole matcher and a fixed parameter sliding window median filter are introduced successively, which improves the detection speed and dynamic performance, effectively avoids the pulse noise introduced by the matcher, enhances the anti-interference ability and robustness, overcomes the defects of slow detection speed and insufficient dynamic response in the prior art, and meets the fast response requirements of the new energy power generation system and flexible power quality equipment for voltage anomaly detection.

[0026] Further, before the step S2, it also includes: Sampling and holding the first positive sequence voltage amplitude and the first negative sequence voltage amplitude, and adjusting the matching coefficient of the variable parameter sliding window zero-pole matcher according to the sampled voltage estimated amplitude, so that the variable parameter sliding window zero-pole matcher enters the preset strong matching mode or the preset weak matching mode.

[0027] As can be seen from the above description, on the variable parameter sliding window zero-pole matcher, according to the sampling results of the first positive sequence voltage amplitude and the first negative sequence voltage amplitude, the matching coefficient of the variable parameter sliding window zero-pole matcher is adjusted to realize the adaptive dynamic adjustment of the variable parameter sliding window zero-pole matcher to enter the preset strong matching mode or the preset weak matching mode, achieving the balance of dynamic and steady-state performance, which can not only quickly identify voltage anomalies but also ensure the convergence accuracy.

[0028] Further, before the step S2, it also includes: Set the adjustment rule of the matching coefficient, and its expression is as follows: ; where k represents the discrete time variable, μ(k) represents the matching coefficient, μ H is the high matching coefficient, μ L is the low matching coefficient, U H is the overvoltage threshold, U L is the undervoltage threshold, U N is the rated voltage value, represents the sampled voltage estimated amplitude.

[0029] As can be seen from the above description, by setting adjustment rules, when the estimated amplitude of the sampled voltage is near the rated voltage, it is adjusted to a preset strong matching mode to accelerate the detection speed; when the estimated amplitude of the sampled voltage is far from the rated voltage, it is adjusted to a preset weak matching mode to improve the detection accuracy; through the dynamic stepless adjustment of the strong / weak matching mode, rapid identification and precise convergence at the initial stage of voltage abnormality are achieved.

[0030] Further, step 3 includes: S31. Create a voltage abnormality flag bit Flag for determining whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition, and its expression is as follows: ; wherein, represents the third positive-sequence voltage amplitude, represents the third negative-sequence voltage amplitude, represents the positive-sequence undervoltage threshold, represents the positive-sequence overvoltage threshold, represents the negative-sequence overvoltage threshold; S32. According to the status of the voltage abnormality flag bit, determine whether to output the three-phase voltage abnormality of the target device.

[0031] As can be seen from the above description, by using the voltage abnormality flag bit as the judgment output result of various preset overvoltage conditions or preset undervoltage conditions, it can accurately and quickly identify whether the three-phase voltage of the target device is abnormal.

[0032] Further, the sampling and holding of the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude are specifically: Sampling and holding the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude according to a preset sampling interval, and its expression is as follows: ; wherein, represents the first positive-sequence voltage amplitude or the first negative-sequence voltage amplitude, M represents the preset sampling interval, represents the floor function.

[0033] As can be seen from the above description, by introducing the floor function, sampling and holding the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude according to a preset sampling interval to obtain a suitable estimated amplitude of the sampled voltage.

[0034] Please refer to Figures 2 to 9 , Example 1 of the present invention is: A three-phase overvoltage, combined with Figure 2 and Figure 3As shown, the undervoltage fast detection method includes the following steps: S1. Estimate the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the target device through the sliding window average filtering detection method based on synchronous rotating coordinate transformation; In this embodiment, as shown in the figure, the three-phase grid voltages u a (t), u b (t), u c (t) are discretely sampled to obtain signals u a (k), u b (k), u c (k). After positive / negative sequence synchronous rotating coordinate transformation (Park transformation), the positive / negative sequence voltage signals u dq (k) on the dq axis are obtained. After passing through the sliding window average filter, the initially estimated first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude of the power grid are obtained. The discretization sampling frequency f s is selected according to the actual controller performance.

[0035] S2. Call the variable parameter sliding window zero-pole matcher to correct the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude respectively to obtain the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude; In this embodiment, the proposed variable parameter sliding window zero-pole matcher is used to correct the original voltage estimated amplitude: and are input into the variable parameter sliding window zero-pole matcher. After dynamic matching, the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude are obtained. The discrete time domain expression of the variable parameter sliding window zero-pole matcher is: ; where k represents the discrete time variable, represents the Nth power of the number of matches, represents the matching coefficient, and N represents the sliding window average window; And the z-domain transfer function of the variable parameter sliding window zero-pole matcher is: ; It should be noted that the variable parameter sliding window zero-pole matcher includes N poles and 1 zero to match the N zeros and 1 pole in the existing fixed parameter sliding window median filter to achieve approximate cancellation of zeros and poles. The matching coefficient can dynamically adjust the matching degree according to the real-time voltage estimated amplitude. When When it is relatively large, the matcher can greatly weaken the hysteresis effect of the original system's zeros and poles, but it may bring negative impacts such as overshoot and disturbance rejection error, which is defined as the strong matching mode; when is relatively small, the role of the matcher weakens, retaining the high steady-state accuracy of the original system, but the dynamic performance is poor, which is defined as the weak matching mode.

[0036] Specifically, before step S2, sample and hold the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude as follows: Sample and hold the first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude according to a preset sampling interval, and its expression is as follows: ; Wherein, represents the first positive-sequence voltage amplitude or the first negative-sequence voltage amplitude, M represents the preset sampling interval, represents the floor function.

[0037] Estimate the matching coefficient of the variable-parameter sliding window zero-pole matcher according to the sampled voltage, so that the variable-parameter sliding window zero-pole matcher enters the preset strong matching mode or the preset weak matching mode. Set the adjustment rule of the matching coefficient, and its expression is as follows: ; Wherein, μ H is the high matching coefficient, μ L is the low matching coefficient, U H is the overvoltage threshold, U L is the undervoltage threshold, U N is the rated voltage value, represents the estimated amplitude of the sampled voltage.

[0038] The parameter adjustment rule after distinguishing positive / negative sequence is: ; Wherein, represents the positive-sequence matching coefficient, represents the positive-sequence high matching coefficient, represents the negative-sequence matching coefficient, represents the negative-sequence high matching coefficient.

[0039] Figure 4 This is the z-domain zero-pole distribution diagram of the zero-pole matcher with different matching degrees of the present invention: when the value is relatively large, the zeros and poles of the matcher are close to the zeros and poles of the sliding window average filter distributed on the unit circle, which can greatly weaken the hysteresis effect of the original system's zeros and poles. As the value becomes smaller, the zeros and poles of the matcher gradually move away from the zeros and poles of the sliding window average filter distributed on the unit circle, and the matching degree gradually decreases.

[0040] Figure 5 Schematic diagram of the step response of the zero-pole matcher with different matching degrees of the present invention: For the system step response with a strong matching degree (large value), the rise time is relatively fast, but there is overshoot, and the convergence performance is poor; after weakening the matching degree (small value), the dynamic performance of the system decreases, but the convergence performance improves.

[0041] Figure 6 and Figure 7 are respectively the schematic diagrams of the curves of the positive / negative sequence parameter adaptive adjustment rules of the present invention: When the adaptive adjustment algorithm is near the rated voltage, the adaptive adjustment is in the strong matching mode (large value), which is sensitive to voltage abnormal events and has a fast recognition speed; when is far from the rated voltage, the adaptive adjustment is in the weak matching mode (small value), the convergence speed decreases but the detection accuracy improves. Through the dynamic stepless adjustment of the strong / weak matching mode, fast recognition and precise convergence at the initial stage of voltage abnormality are realized.

[0042] S3. Call the fixed-parameter sliding window median filter to perform median filtering on the second positive-sequence voltage amplitude and the second negative-sequence voltage amplitude respectively, and obtain the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude; Use the sliding window median filtering of the nearest M points to eliminate the pulse noise that may be caused by variable parameters. The expression is as follows: ; wherein, represents the third positive-sequence voltage amplitude or the third negative-sequence voltage amplitude. Specifically it is the third positive-sequence voltage amplitude, is the third negative-sequence voltage amplitude.

[0043] S4. Judge whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet the preset overvoltage condition or the preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

[0044] Based on the estimated amplitudes of the positive / negative sequence voltages after median filtering and , conduct a comprehensive logical judgment on over / undervoltage events. When the estimated positive-sequence amplitude reaches the over / undervoltage threshold or the estimated negative-sequence amplitude reaches the overvoltage threshold (three-phase asymmetry), it is judged as a three-phase voltage abnormal event. The expression of the voltage abnormal flag bit Flag is as follows: ; wherein, represents the third positive-sequence voltage amplitude, represents the third negative-sequence voltage amplitude, represents the positive-sequence under-voltage threshold, represents the positive-sequence over-voltage threshold, represents the negative-sequence over-voltage threshold.

[0045] S32. According to the status of the voltage anomaly flag bit, determine whether to output the three-phase voltage anomaly of the target device.

[0046] Regarding the application of a three-phase over-voltage or under-voltage rapid detection method of this embodiment, examples are as follows: In a dynamic voltage restorer (DVR), it is used to quickly detect grid anomaly events. The effectiveness of the present invention is demonstrated by comparing the waveforms of the existing technical method and the method of the present invention under the same grid over / under-voltage conditions. Overall, the specific parameter settings of the three-phase over / under-voltage rapid detection method are as follows: (1) Select the sampling frequency fs to be 10 kHz, the sliding window average window N to be 100, and the sampling and holding window and the sliding window median filtering window M to be 5; (2) Select the positive-sequence high matching coefficient to be 0.99, the positive-sequence low matching coefficient to be 0.90, the negative-sequence high matching coefficient to be 0.98, and the negative-sequence high matching coefficient to be 0.80; (3) The rated positive-sequence voltage value is 1.0 p.u., the positive-sequence over / under-voltage thresholds and are 1.1 p.u. and 0.9 p.u. respectively, the rated negative-sequence voltage value is 0.0 p.u., and the negative-sequence over-voltage threshold is 0.1 p.u.

[0047] Figure 8 The waveform schematic diagram of the method of the present invention under the three-phase grid symmetric sag condition: The existing sliding window average detection method takes 5.1 ms to determine that the positive-sequence voltage is lower than the positive-sequence under-voltage threshold, while the variable-parameter matching method of the present invention can identify the anomaly event within 0.1 ms. And due to the effect of dynamic parameter adjustment, the positive-sequence steady-state convergence accuracy is comparable to that of the existing method. The estimated amplitudes of the negative-sequence voltages of both methods do not exceed the over-voltage threshold, indicating that no false detection occurs and the robustness performance is good. In this condition, the dynamic voltage restorer DVR applying the present invention can make a response within 0.1 ms.

[0048] Figure 9Waveform diagram of the method of the present invention under the condition of asymmetric sudden rise (including 5th and 7th harmonics) in a three-phase power grid: The existing sliding window average detection method takes 4.4 ms and 3.7 ms to determine that the positive / negative sequence voltage exceeds the voltage threshold, while the variable parameter matching method of the present invention takes 2.7 ms and 1.0 ms to identify abnormal events of the positive / negative sequence voltage. The detection time after comprehensive judgment is 1.0 ms. And due to the effect of dynamic parameter adjustment, there is almost no overshoot phenomenon in the process of estimating the positive / negative sequence voltage, the convergence speed is faster, and the steady-state convergence accuracy is comparable to that of the existing method and is not affected by harmonics. In this condition, the dynamic voltage restorer DVR of the present invention can respond within 1.0 ms.

[0049] Please refer to Figure 10 , the second embodiment of the present invention is: A three-phase overvoltage or undervoltage rapid detection terminal 1, including a memory 2, a processor 3, and a computer program stored on the memory 2 and executable on the processor 3. When the processor 3 executes the computer program, it implements a three-phase overvoltage or undervoltage rapid detection method of Embodiment 1.

[0050] In summary, a three-phase overvoltage or undervoltage rapid detection method and terminal provided by the present invention use the existing sliding window average filtering detection method based on synchronous rotating coordinate transformation to estimate the first positive sequence voltage amplitude and the first negative sequence voltage amplitude of the target device, and successively correct and median filter the first positive sequence voltage amplitude and the first negative sequence voltage amplitude to obtain the third positive sequence voltage amplitude and the third negative sequence voltage amplitude, and complete the detection of three-phase voltage anomalies in combination with preset overvoltage conditions or preset undervoltage conditions. During this period, a variable parameter sliding window zero-pole matcher and a fixed parameter sliding window median filter are introduced successively, which improves the detection speed and dynamic performance, effectively avoids the pulse noise introduced by the matcher, enhances the anti-interference ability and robustness, overcomes the defects of slow detection speed and insufficient dynamic response in the prior art, and meets the fast response requirements of new energy power generation systems and flexible power quality equipment for voltage anomaly detection.

[0051] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent transformations made by using the specification and drawings of the present invention, or directly or indirectly applied in related technical fields, are equally included in the patent protection scope of the present invention.

Claims

1. A three-phase overvoltage or undervoltage rapid detection method, characterized in that: The steps include: S1. Pre-estimating a first positive-sequence voltage amplitude and a first negative-sequence voltage amplitude of a target device by a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2, calling a variable parameter sliding window zero-pole matcher to respectively correct the first positive sequence voltage amplitude and the first negative sequence voltage amplitude to obtain a second positive sequence voltage amplitude and a second negative sequence voltage amplitude; S3, calling a fixed parameter sliding window median filter to perform median filtering on the second positive sequence voltage amplitude and the second negative sequence voltage amplitude respectively, to obtain a third positive sequence voltage amplitude and a third negative sequence voltage amplitude; S4. Determine whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet a preset overvoltage condition or a preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

2. A three-phase overvoltage or undervoltage rapid detection method according to claim 1, characterized in that: Before step S2, the following steps are also included: The first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude are sampled and maintained, and the matching coefficient of the variable parameter sliding window zero-pole matcher is adjusted according to the sampled voltage estimation amplitude, so that the variable parameter sliding window zero-pole matcher enters a preset strong matching mode or a preset weak matching mode.

3. A three-phase overvoltage or undervoltage rapid detection method according to claim 2, characterized in that: Before step S2, the following steps are also included: The adjustment rule for setting the matching coefficient is as follows: ； Wherein, k represents a discrete time variable, μ(k) represents the matching coefficient, and μ H For high matching coefficient, μ L For low matching coefficient, U H Overvoltage threshold, U L Undervoltage threshold, U N is the rated voltage value, Represents the estimated amplitude of the sampled voltage.

4. A three-phase overvoltage or undervoltage rapid detection method according to claim 1, characterized in that: The step S3 comprises: S31, creating a voltage abnormality flag Flag for judging whether the third positive sequence voltage amplitude and the third negative sequence voltage amplitude meet a preset overvoltage condition or a preset undervoltage condition, and the expression thereof is as follows: ； in, represents the third positive sequence voltage amplitude, represents the third negative sequence voltage amplitude, Indicates the positive sequence undervoltage threshold, represents the positive sequence overvoltage threshold, Indicates the negative sequence overvoltage threshold; S32. Determine whether the output three-phase voltage of the target device is abnormal according to the state of the voltage abnormality flag.

5. A three-phase overvoltage or undervoltage rapid detection method according to claim 2, characterized in that: The sampling and maintaining of the first positive sequence voltage amplitude and the first negative sequence voltage amplitude is specifically as follows: The first positive sequence voltage amplitude and the first negative sequence voltage amplitude are sampled and maintained according to a preset sampling interval, and the expressions are as follows: ； in, represents the first positive sequence voltage amplitude or the first negative sequence voltage amplitude, M represents the preset sampling interval, Represents the floor function.

6. A three-phase overvoltage or undervoltage rapid detection 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, the following steps are implemented: S1. Pre-estimating a first positive-sequence voltage amplitude and a first negative-sequence voltage amplitude of a target device by a sliding window average filtering detection method based on synchronous rotating coordinate transformation; S2, calling a variable parameter sliding window zero-pole matcher to respectively correct the first positive sequence voltage amplitude and the first negative sequence voltage amplitude to obtain a second positive sequence voltage amplitude and a second negative sequence voltage amplitude; S3, calling a fixed parameter sliding window median filter to perform median filtering on the second positive sequence voltage amplitude and the second negative sequence voltage amplitude respectively, to obtain a third positive sequence voltage amplitude and a third negative sequence voltage amplitude; S4. Determine whether the third positive-sequence voltage amplitude and the third negative-sequence voltage amplitude meet a preset overvoltage condition or a preset undervoltage condition. If so, output that the three-phase voltage of the target device is abnormal.

7. A three-phase overvoltage or undervoltage rapid detection terminal according to claim 6, characterized in that: Before step S2, the following steps are also included: The first positive-sequence voltage amplitude and the first negative-sequence voltage amplitude are sampled and maintained, and the matching coefficient of the variable parameter sliding window zero-pole matcher is adjusted according to the sampled voltage estimation amplitude, so that the variable parameter sliding window zero-pole matcher enters a preset strong matching mode or a preset weak matching mode.

8. A three-phase overvoltage or undervoltage rapid detection terminal according to claim 7, characterized in that: Before step S2, the following steps are also included: The adjustment rule for setting the matching coefficient is as follows: ； Wherein, k represents a discrete time variable, μ(k) represents the matching coefficient, and μ H For high matching coefficient, μ L For low matching coefficient, U H Overvoltage threshold, U L Undervoltage threshold, U N is the rated voltage value, Represents the estimated amplitude of the sampled voltage.

9. A three-phase overvoltage or undervoltage rapid detection terminal according to claim 6, characterized in that: The step S3 comprises: S31, creating a voltage abnormality flag Flag for judging whether the third positive sequence voltage amplitude and the third negative sequence voltage amplitude meet a preset overvoltage condition or a preset undervoltage condition, and the expression thereof is as follows: ； in, represents the third positive sequence voltage amplitude, represents the third negative sequence voltage amplitude, Indicates the positive sequence undervoltage threshold, represents the positive sequence overvoltage threshold, Indicates the negative sequence overvoltage threshold; S32. Determine whether the output three-phase voltage of the target device is abnormal according to the state of the voltage abnormality flag.

10. A three-phase overvoltage or undervoltage rapid detection terminal according to claim 7, characterized in that: The sampling and maintaining of the first positive sequence voltage amplitude and the first negative sequence voltage amplitude is specifically as follows: The first positive sequence voltage amplitude and the first negative sequence voltage amplitude are sampled and maintained according to a preset sampling interval, and the expressions are as follows: ； in, represents the first positive sequence voltage amplitude or the first negative sequence voltage amplitude, M represents the preset sampling interval, Represents the floor function.

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