UPQC bypass protection thyristor self-checking method and system and storage medium

Abstract

The invention discloses a UPQC bypass protection thyristor self-checking method and system and a storage medium, and the method comprises the steps: carrying out the primary self-checking of a bypass protection thyristor before a series side DC / AC power module of a UPQC carries out the voltage out-of-limit treatment, and judging whether the bypass protection thyristor has a fault or not; in response to the situation that the bypass protection thyristor does not have a fault, a voltage out-of-limit treatment work instruction is sent to the series side DC / AC power module, meanwhile, continuous self-inspection processing is carried out on the bypass protection thyristor, and whether the bypass protection thyristor is mistakenly conducted or not is judged; in response to the fault of the bypass protection thyristor or the misconduction of the bypass protection thyristor, sending a shutdown instruction to the series side DC / AC power module; and in response to the situation that the bypass protection thyristor does not have the fault and the bypass protection thyristor does not have the error conduction, sending a voltage out-of-limit treatment work instruction to the series side DC / AC power module. According to the invention, the problem that the existing UPQC cannot realize the self-inspection of the bypass protection thyristor is solved.

Description

Technical Field

[0001] This invention relates to the technical field of power electronics and power quality management of distribution networks, and particularly to a UPQC bypass protection thyristor self-testing method, system, and storage medium. Background Technology

[0002] In recent years, with the large-scale integration of distributed new energy sources and new loads, the increased uncertainty of power sources and loads has made power quality problems such as voltage fluctuations and three-phase imbalances in distribution networks more prominent. Especially at the end of long distribution lines, due to the high line impedance, when distributed power sources or loads change, voltage exceeding limits and other problems are likely to occur at the end of the line, posing safety hazards to the operation of the power grid and equipment.

[0003] Therefore, to solve the power quality problem in the distribution network, the application of Unified Power Quality Conditioner (UPQC) is increasing. The entire system is connected in series in the power grid line. The DC / AC power module on the series side inverts the output voltage according to the command and injects it into the series transformer and couples it to the line to realize voltage over-limit management and ensure that the voltage at the end of the line is within the limit range. At the same time, the AC / DC power module on the parallel side is connected in parallel to the power grid line to perform reactive power or three-phase imbalance compensation, thereby effectively improving the local power quality of the distribution network.

[0004] Because the UPQC is connected in series in the line, when a partial short-circuit fault occurs, the grid voltage is directly applied to the low-voltage side of the series-coupled transformer, causing damage to the transformer, power modules, etc., due to overvoltage. Therefore, a three-phase low-voltage bypass thyristor can be connected in parallel between the DC / AC power module and the transformer on the series side. Under normal operation, the thyristor is open; when a line fault occurs, the thyristor quickly closes, bypassing the AC port of the series-coupled module and one side of the transformer, thus preventing equipment damage due to overvoltage.

[0005] The ability of thyristors to operate correctly according to instructions determines the proper functioning of UPQC (Upgraded Quality Control) and its ability to provide fault protection. Therefore, functional testing of thyristors is crucial, especially when the equipment has been in operation for a long time. Effective self-testing of thyristors is key to ensuring the safe and stable operation of the equipment. However, current thyristor testing is basically limited to the equipment manufacturing stage, and cannot guarantee that the thyristor status can be automatically detected and faults can be troubleshooted in a timely manner after the equipment is put into operation. Summary of the Invention

[0006] The purpose of this invention is to provide a method, system, and storage medium for self-testing of UPQC bypass protection thyristors. The method solves the problem that existing UPQCs cannot perform self-testing of bypass protection thyristors, thereby improving the safety protection capability and reliability of UPQCs.

[0007] In a first aspect, the present invention provides a self-testing method for a UPQC bypass protection thyristor, wherein the UPQC includes a series-side DC / AC power module, a parallel-side AC / DC power module, a bypass protection thyristor, and a series-coupled transformer; the parallel-side AC / DC power module is connected in parallel to the power grid line, and its DC side is connected to the DC side of the series-side DC / AC power module; the series-side DC / AC power module and the series-coupled transformer are connected in series to the power grid line; the bypass protection thyristor is connected in parallel between the series-side DC / AC power module and the series-coupled transformer; including: Before performing voltage over-limit management on the DC / AC power module on the series side of UPQC, perform an initial self-test on the bypass protection thyristor to determine if there is a fault in the bypass protection thyristor. In response to the absence of a fault in the bypass protection thyristor, a voltage over-limit mitigation command is issued to the DC / AC power module on the series side. At the same time, the bypass protection thyristor is continuously self-tested to determine whether there is any false triggering. In response to a fault in the bypass protection thyristor or a false triggering of the bypass protection thyristor, a shutdown command is issued to the DC / AC power module on the series side. In response to the absence of faults in the bypass protection thyristor and the absence of false triggering in the bypass protection thyristor, a voltage over-limit mitigation command is issued to the series-side DC / AC power module.

[0008] Optionally, the initial self-test of the bypass protection thyristor includes: The bypass protection thyristor is tested for its conduction function. If the bypass protection thyristor does not conduct normally, it is determined that the bypass protection thyristor is faulty. If the bypass protection thyristor is conducting normally, the bypass protection thyristor is tested for shutdown function. If the bypass protection thyristor is shut off normally, it is determined that there is no fault in the bypass protection thyristor; otherwise, it is determined that there is a fault in the bypass protection thyristor.

[0009] Optionally, the time ratios for the conduction function detection and the shutdown function detection are the same.

[0010] Optionally, the bypass protection thyristor includes a three-phase thyristor, and each phase thyristor is equipped with its own on-state voltage over-limit counter. The conduction function test of the bypass protection thyristor includes: Initialize the on-voltage over-limit counters for each phase thyristor; The first control command is issued to the series-side DC / AC power module in UPQC, causing the series-side DC / AC power module to output a three-phase low voltage; and at the same time, a turn-on command is issued to the three-phase thyristors, causing the three-phase thyristors to turn on. During the conduction function detection period, the three-phase voltage sampling results output by the DC / AC power module on the series side are collected according to the sampling period and the voltage over-limit judgment is performed. If the voltage sampling result exceeds the first preset voltage threshold, the conduction voltage over-limit counter value of the phase to which the voltage sampling result belongs will be incremented by 1; If the count value of the on-state voltage over-limit counter exceeds the first threshold, it is determined that the thyristor corresponding to the phase of the on-state voltage over-limit counter has not been turned on normally during the on-state function detection period, and the bypass protection thyristor is faulty. If the over-voltage counter values ​​of the three-phase thyristors do not exceed the first threshold, then it is determined that there is no fault in the bypass protection thyristor.

[0011] Optionally, each thyristor in each phase is equipped with its own turn-off voltage accumulator; The detection of the bypass protection thyristor's shutdown function includes: Initialize the turn-off voltage accumulator for each phase thyristor; When the bypass protection thyristor is normally turned on, the series-side DC / AC power module continuously outputs three-phase low voltage, and at the same time sends a turn-off command to the three-phase thyristor to turn off the three-phase thyristor. During the shutdown function detection period, the three-phase voltage sampling results output by the DC / AC power module on the series side are collected according to the sampling period, and the voltage sampling results of each phase are accumulated to the shutdown voltage accumulator of the corresponding phase thyristor to obtain the voltage accumulation result of each phase. Based on the cumulative results of the phase voltages, the periodic average results of the phase voltages are obtained; If the average voltage cycle result is lower than the second preset voltage threshold, the thyristor of the corresponding phase is not turned off normally, and the bypass protection thyristor is faulty. If the average voltage cycle of each phase is not lower than the second preset voltage threshold, then there is no fault in the bypass protection thyristor.

[0012] Optionally, the continuous self-testing process for the bypass protection thyristor includes: When managing voltage over-limits, if the voltage value of a certain phase of the DC / AC power module on the series side exceeds the third preset voltage threshold for 3 seconds, the low-voltage side voltage of that phase of the series-coupled transformer is detected; if the low-voltage side voltage of that phase is less than the preset voltage value for 5ms, it is determined that the bypass protection thyristor of that phase is mis-energized.

[0013] Secondly, the present invention provides a UPQC bypass protection thyristor self-test system, comprising: The initial self-test processing module is used to perform an initial self-test on the bypass protection thyristor before voltage over-limit management is performed on the DC / AC power module on the series side of UPQC, to determine whether there is a fault in the bypass protection thyristor. The continuous self-test processing module, in response to the absence of a fault in the bypass protection thyristor, issues a voltage over-limit management instruction to the series-side DC / AC power module, and simultaneously performs continuous self-test processing on the bypass protection thyristor to determine whether there is any false triggering of the bypass protection thyristor. The result processing module, in response to a fault in the bypass protection thyristor or a false turn-on of the bypass protection thyristor, issues a shutdown command to the series-side DC / AC power module; in response to no fault in the bypass protection thyristor and no false turn-on of the bypass protection thyristor, issues a voltage over-limit mitigation command to the series-side DC / AC power module.

[0014] Optionally, the initial self-test processing module includes: The continuity function detection submodule is used to detect the continuity function of the bypass protection thyristor. If the bypass protection thyristor is not conducting normally, it is determined that the bypass protection thyristor is faulty. The shutdown function detection submodule is used to perform shutdown function detection on the bypass protection thyristor if it is normally turned on. If the bypass protection thyristor is normally turned off, it is determined that there is no fault in the bypass protection thyristor; otherwise, it is determined that there is a fault in the bypass protection thyristor.

[0015] Optionally, the continuous self-test processing module includes: The detection submodule is used to detect the low-voltage side voltage of the series-coupled transformer when the voltage value of a certain phase of the series-connected DC / AC power module exceeds the third preset voltage threshold for 3 consecutive seconds during voltage over-limit management. The mis-circuit protection thyristor detection submodule is used to determine that the bypass protection thyristor of a phase is mis-circuited if the low-voltage side voltage of the phase is less than the preset voltage value for 5ms.

[0016] Thirdly, the present invention provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed, implements the UPQC bypass protection thyristor self-test method described in the first aspect.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a method, system, and storage medium for self-testing of a bypass protection thyristor in a UPQC (Upgraded Voltage Control Center). Before the UPQC performs voltage over-limit mitigation, the method performs an initial self-test on the bypass protection thyristor to obtain the initial self-test result. Based on the initial self-test result, it determines whether to shut down or perform continuous self-testing. When the UPQC performs voltage over-limit mitigation, it performs continuous self-testing to determine whether the bypass protection thyristor has a false triggering capability, obtaining the continuous self-test result. Based on the continuous self-test result, it determines whether to issue a shutdown command or continue voltage over-limit mitigation instructions. The initial self-test process performs a self-test on the thyristor's on / off function before voltage over-limit mitigation. It uses the AC voltage output from the series-side DC / AC power module and the thyristor's on / off action, along with a comprehensive analysis based on the measured voltage (on-function detection is based on count values, and off-function detection is based on accumulated average values), to determine if the thyristor is faulty. The continuous self-test process performs real-time detection and judgment on whether the thyristor has a false on-off fault during voltage over-limit mitigation. By combining these two self-test processes, this invention can detect on-off and off-off faults in the bypass protection thyristor and prevent overcurrent damage to the UPQC component due to thyristor false on-off during operation, significantly enhancing the overall safety and reliability of the device. Attached Figure Description

[0018] Figure 1 The diagram shown is a schematic representation of the steps of the UPQC bypass protection thyristor self-test method in one embodiment of the present invention. Figure 2 The diagram shown is an electrical schematic of the main circuit of the UPQC unit in one embodiment of the present invention; Figure 3 The diagram shown is a flowchart of a UPQC bypass protection thyristor self-test method in one embodiment of the present invention. Figure 4 The diagram shown is a schematic diagram of the conduction function detection process in one embodiment of the present invention; Figure 5 The diagram shown is a schematic of the shutdown function detection process in one embodiment of the present invention. Detailed Implementation

[0019] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0020] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0021] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0022] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0023] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0024] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] Example 1

[0026] like Figure 1 As shown in the figure, this embodiment of the invention introduces a self-test method for UPQC bypass protection thyristors, including the following steps: S01: Before performing voltage over-limit management on the DC / AC power module on the series side of UPQC, perform an initial self-test on the bypass protection thyristor to determine whether there is a fault in the bypass protection thyristor. S02: In response to the absence of a fault in the bypass protection thyristor, a voltage over-limit management instruction is issued to the DC / AC power module on the series side. At the same time, the bypass protection thyristor is continuously self-tested to determine whether there is any false triggering of the bypass protection thyristor. S03: In response to a fault in the bypass protection thyristor or a false turn-on of the bypass protection thyristor, a shutdown command is issued to the DC / AC power module on the series side; in response to no fault in the bypass protection thyristor and no false turn-on of the bypass protection thyristor, a voltage over-limit mitigation command is issued to the DC / AC power module on the series side.

[0027] This invention provides a self-test method for UPQC bypass protection thyristors, wherein, as shown in the embodiments of the present invention... Figure 2 The diagram shows the main circuit electrical schematic of the UPQC unit. In the diagram, Mk1 represents the parallel-side AC / DC power module, and Mk2 represents the series-side DC / AC power module. The UPQC includes a series-side DC / AC power module, a parallel-side AC / DC power module, a bypass protection thyristor, and a series coupling transformer. The parallel-side AC / DC power module is connected in parallel to the power grid line, and its DC side is connected to the DC side of the series-side DC / AC power module. The series-side DC / AC power module and the series coupling transformer are connected in series to the power grid line. A bypass protection thyristor is connected in parallel between the series-side DC / AC power module and the series coupling transformer. UPQC allows you to enable the self-test function and set the self-test time. It performs a self-test on the thyristors before and during each voltage over-limit mitigation operation, i.e., initial self-test and continuous self-test. Figure 3 As shown; During the self-test process, the parallel-side AC / DC power module UDC voltage regulator is first activated to provide DC voltage to the series-side DC / AC power module. Before initiating voltage over-limit management, the bypass protection thyristor undergoes its initial self-test. During this period, the series-side DC / AC power module outputs three-phase low voltage and controls the thyristors to turn on and off respectively. The phase voltage is then detected to determine whether the thyristors can turn on and off normally. When dealing with normal voltage over-limit issues, the system enters the continuous self-test process of the bypass protection thyristor, and detects the low-voltage side voltage of the series-coupled transformer to determine whether the thyristor has mis-energized. If the self-test results indicate a bypass protection thyristor fault (including false triggering) through the two self-test methods described above, a shutdown command is sent to the series-side DC / AC power module to stop the series-side DC / AC power module from operating by blocking the pulse.

[0028] If the self-test result shows that the thyristor is fault-free, a voltage over-limit mitigation command is sent to the series-side DC / AC power module, causing the series-side DC / AC power module to operate according to the voltage over-limit mitigation requirements.

[0029] It should be noted that there are one or more AC / DC power modules on the parallel side and one or more DC / AC power modules on the series side.

[0030] It should be noted that after the parallel-side AC / DC power module of UPQC is started, under the condition that the bypass protection thyristor self-test function is enabled, the detection timer is initialized and started to begin the initial self-test of the bypass protection thyristor.

[0031] In this embodiment, the initial self-test of the bypass protection thyristor is performed, specifically including: S21: Perform conduction function test on the bypass protection thyristor. If the bypass protection thyristor does not conduct normally, it is determined that the bypass protection thyristor is faulty. S22: If the bypass protection thyristor is normally turned on, the bypass protection thyristor is turned off. If the bypass protection thyristor is normally turned off, it is determined that there is no fault in the bypass protection thyristor; otherwise, it is determined that there is a fault in the bypass protection thyristor.

[0032] Specifically, the initial self-test processing period is divided into two phases: the thyristor conduction function test period and the thyristor turn-off function test period. Both phases are half of the initial self-test processing period.

[0033] In an optional embodiment, the initial self-test processing function is enabled by default, and the self-test time is 4 seconds by default, of which 0-2 seconds is the conduction function detection period and 2-4 seconds is the shutdown function detection period.

[0034] Specifically, the bypass protection thyristor includes a three-phase thyristor, and each phase thyristor is equipped with its own on-state voltage over-limit counter; like Figure 4 As shown, the conduction function test of the bypass protection thyristor includes: Initialize the on-voltage over-limit counters for each phase thyristor; The first control command is issued to the series-side DC / AC power module in UPQC, causing the series-side DC / AC power module to output a three-phase low voltage; and at the same time, a turn-on command is issued to the three-phase thyristors, causing the three-phase thyristors to turn on. During the conduction function detection period, the three-phase voltage sampling results output by the DC / AC power module on the series side are collected according to the sampling period and the voltage over-limit judgment is performed. If the voltage sampling result exceeds the first preset voltage threshold, the conduction voltage over-limit counter value of the phase to which the voltage sampling result belongs will be incremented by 1; If the count value of the on-state voltage over-limit counter exceeds the first threshold, it is determined that the thyristor corresponding to the phase of the on-state voltage over-limit counter has not been turned on normally during the on-state function detection period, and the bypass protection thyristor is faulty. If the over-voltage counter values ​​of the three-phase thyristors do not exceed the first threshold, then it is determined that there is no fault in the bypass protection thyristor.

[0035] In one optional instance, during the conduction function detection period, the series-side DC / AC power module sets the output three-phase AC voltage to 30V and issues a three-phase thyristor conduction command. The sampling period during the conduction function period is 1ms, and the voltage threshold is 10V. That is, if the voltage sampling result of a certain phase exceeds 10V, the corresponding conduction voltage over-limit counter is incremented by 1.

[0036] At the end of the conduction function detection period, the conduction voltage over-limit counter is counted and judged. The threshold is 200. That is, if the voltage exceeds 10V 200 times, the corresponding thyristor is considered to be faulty, otherwise the conduction is considered successful.

[0037] In this embodiment, each phase of the thyristor is equipped with its own turn-off voltage accumulator; The bypass protection thyristor is tested for its shutdown function, specifically including: Initialize the turn-off voltage accumulator for each phase thyristor; When the bypass protection thyristor is normally turned on, the series-side DC / AC power module continuously outputs three-phase low voltage, and at the same time sends a turn-off command to the three-phase thyristor to turn off the three-phase thyristor. During the shutdown function detection period, the three-phase voltage sampling results output by the DC / AC power module on the series side are collected according to the sampling period, and the voltage sampling results of each phase are accumulated to the shutdown voltage accumulator of the corresponding phase thyristor to obtain the voltage accumulation result of each phase. Based on the cumulative results of the phase voltages, the periodic average results of the phase voltages are obtained; If the average voltage cycle result is lower than the second preset voltage threshold, the thyristor of the corresponding phase is not turned off normally, and the bypass protection thyristor is faulty. If the average voltage cycle of each phase is not lower than the second preset voltage threshold, then there is no fault in the bypass protection thyristor.

[0038] In one optional instance, during the shutdown function detection period, the series-side DC / AC power module sets the output three-phase AC voltage to 30V and issues a thyristor shutdown command. The sampling period during the thyristor shutdown function period is 1ms.

[0039] At the end of the shutdown function detection period, the average voltage of each phase thyristor is judged. The threshold is 20V. That is, if the average voltage of a phase thyristor is lower than 20V, the corresponding phase thyristor is considered to be faulty, otherwise the shutdown is considered to be successful.

[0040] In this embodiment, after the initial self-test of the thyristors, if the initial self-test result indicates a thyristor fault, a shutdown command is sent to the series-side DC / AC power module, causing the series-side DC / AC power module to stop operating by blocking pulses. If the initial self-test result indicates no thyristor fault, meaning that the three-phase thyristors' turn-on and turn-off functions are normal, a voltage over-limit mitigation command is sent to the series-side DC / AC power module, causing the series-side DC / AC power module to start operating according to the voltage over-limit mitigation requirements.

[0041] In this embodiment, during voltage over-limit mitigation, the bypass protection thyristor undergoes continuous self-testing, including: When managing voltage over-limits, if the voltage value of a certain phase of the DC / AC power module on the series side exceeds the third preset voltage threshold for 3 seconds, the low-voltage side voltage of that phase of the series-coupled transformer is detected; if the low-voltage side voltage of that phase is less than the preset voltage value for 5ms, it is determined that the bypass protection thyristor of that phase is mis-energized.

[0042] Specifically, after determining that the bypass protection thyristor of the phase is falsely turned on, a shutdown command is sent to the DC / AC power module on the series side, causing the DC / AC power module on the series side to stop working due to the blocking pulse.

[0043] Example 2

[0044] Based on the UPQC bypass protection thyristor method provided in Embodiment 1, this embodiment of the invention introduces a UPQC bypass protection thyristor self-test system, including: The initial self-test processing module is used to perform an initial self-test on the bypass protection thyristor before voltage over-limit management is performed on the DC / AC power module on the series side of UPQC, to determine whether there is a fault in the bypass protection thyristor. The continuous self-test processing module, in response to the absence of a fault in the bypass protection thyristor, issues a voltage over-limit management instruction to the series-side DC / AC power module, and simultaneously performs continuous self-test processing on the bypass protection thyristor to determine whether there is any false triggering of the bypass protection thyristor. The result processing module, in response to a fault in the bypass protection thyristor or a false turn-on of the bypass protection thyristor, issues a shutdown command to the series-side DC / AC power module; in response to no fault in the bypass protection thyristor and no false turn-on of the bypass protection thyristor, issues a voltage over-limit mitigation command to the series-side DC / AC power module.

[0045] Specifically, the initial self-test processing module includes: The continuity function detection submodule is used to detect the continuity function of the bypass protection thyristor. If the bypass protection thyristor is not conducting normally, it is determined that the bypass protection thyristor is faulty. The shutdown function detection submodule is used to perform shutdown function detection on the bypass protection thyristor if it is normally turned on. If the bypass protection thyristor is normally turned off, it is determined that there is no fault in the bypass protection thyristor; otherwise, it is determined that there is a fault in the bypass protection thyristor.

[0046] Specifically, the continuous self-test processing module includes: The detection submodule is used to detect the low-voltage side voltage of the series-coupled transformer when the voltage value of a certain phase of the series-connected DC / AC power module exceeds the third preset voltage threshold for 3 consecutive seconds during voltage over-limit management. The mis-circuit protection thyristor detection submodule is used to determine that the bypass protection thyristor of a phase is mis-circuited if the low-voltage side voltage of the phase is less than the preset voltage value for 5ms.

[0047] It should be noted that the technical solution of this UPQC bypass protection thyristor self-test system is based on the same concept as the technical solution of the above-mentioned UPQC bypass protection thyristor self-test method. For details not described in detail in the technical solution of the UPQC bypass protection thyristor self-test system in this embodiment, please refer to the description of the technical solution of the above-mentioned UPQC bypass protection thyristor self-test method.

[0048] Example 3

[0049] Based on the UPQC bypass protection thyristor self-test method provided in Embodiment 1, this embodiment further illustrates the present invention in conjunction with specific embodiments.

[0050] In this embodiment, a 200kVA UPQC is used as the device under test. The device under test includes a parallel-side AC / DC power module and a series-side DC / AC power module. When performing voltage over-limit mitigation, the parallel-side AC / DC power module operates in UDC voltage regulation mode, providing DC voltage to the series-side DC / AC power module. Before starting voltage over-limit mitigation, the series-side DC / AC module performs an initial thyristor self-test to test whether the thyristor's turn-on and turn-off functions are normal.

[0051] The initial self-test time is set to 4 seconds, with 0-2 seconds for thyristor conduction function testing and 2-4 seconds for thyristor turn-off function testing. During the testing period, the three-phase AC voltage output of the series-side DC / AC power module is set to 30V. The conduction voltage over-limit counter threshold for the conduction function test is 200. If the count exceeds 200, the corresponding phase thyristor is considered faulty; otherwise, conduction is considered successful. The average thyristor voltage threshold for the thyristor turn-off function test is 20V. If the average voltage of a phase thyristor is below 20V, the corresponding phase thyristor is considered faulty; otherwise, turn-off is considered successful.

[0052] The test was conducted using a thyristor that was functioning normally. The results of the thyristor on-state voltage over-limit counter during the thyristor on-state function test period and the average thyristor voltage during the thyristor off-state function test period were recorded, as shown in Table 1. Table 1. Thyristor self-test results data

[0053] As shown in Table 1, when using a thyristor that is functioning normally for testing, the voltage over-limit counter count value during the thyristor conduction detection period is less than the threshold of 200, and the average thyristor voltage during the thyristor turn-off detection period is greater than the threshold of 20V. This means that the three-phase thyristor conduction and turn-off functions are normal. After the self-test is completed, the series side module begins the voltage over-limit mitigation work.

[0054] The test was repeated. To simulate a thyristor problem, the connection between the A-phase thyristor and the series-side module was disconnected, and the thyristor self-test was restarted. The thyristor conduction voltage over-limit counter results during the thyristor conduction function test period were recorded, as shown in Table 2. Table 2. Thyristor self-test results data

[0055] As can be seen from Table 2, during the thyristor conduction detection period, the count value of voltage over-limit counter 1 exceeds the threshold of 200. Therefore, the thyristor of phase A is determined to be faulty, and the thyristor turn-off function detection is skipped. Due to the thyristor fault, the blocking pulse of the series-side DC / AC power module stops working.

[0056] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0057] Example 4

[0058] This embodiment provides a computer-readable storage medium storing a computer program, which, when executed, implements the UPQC bypass protection thyristor self-test method described in Embodiment 1.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for self-checking of bypass protection thyristor of UPQC, wherein, The UPQC comprises a series side DC / AC power module, a parallel side AC / DC power module, a bypass protection thyristor and a series coupling transformer; the parallel side AC / DC power module is connected in parallel on a power grid line, and the DC side thereof is connected to the DC side of the series side DC / AC power module; the series side DC / AC power module and the series coupling transformer are connected in series on the power grid line; the bypass protection thyristor is connected in parallel between the series side DC / AC power module and the series coupling transformer; and the UPQC is characterized in that it comprises: Before the series side DC / AC power module of the UPQC performs voltage out-of-limit management, the bypass protection thyristor is subjected to initial self-checking processing to determine whether the bypass protection thyristor has a fault; In response to the bypass protection thyristor having no fault, a voltage out-of-limit management operation instruction is sent to the series side DC / AC power module, and the bypass protection thyristor is subjected to continuous self-checking processing to determine whether the bypass protection thyristor has a false turn-on; In response to the bypass protection thyristor having a fault or the bypass protection thyristor having a false turn-on, a shutdown instruction is sent to the series side DC / AC power module; In response to the bypass protection thyristor having no fault and the bypass protection thyristor having no false turn-on, a voltage out-of-limit management operation instruction is sent to the series side DC / AC power module.

2. The UPQC bypass protection thyristor self-checking method according to claim 1, characterized in that, The initial self-checking processing of the bypass protection thyristor comprises: The bypass protection thyristor is subjected to turn-on function detection, and if the bypass protection thyristor does not normally turn on, it is determined that the bypass protection thyristor has a fault; If the bypass protection thyristor normally turns on, the bypass protection thyristor is subjected to turn-off function detection, and if the bypass protection thyristor normally turns off, it is determined that the bypass protection thyristor has no fault; otherwise, it is determined that the bypass protection thyristor has a fault.

3. The UPQC bypass protection thyristor self-checking method according to claim 2, characterized in that, The time proportion of the turn-on function detection and the turn-off function detection is the same.

4. The UPQC bypass protection thyristor self-checking method according to claim 3, characterized in that, The bypass protection thyristor comprises three-phase thyristors, and each phase of the thyristors is configured with a corresponding turn-on voltage out-of-limit counter; The turn-on function detection of the bypass protection thyristor comprises: The turn-on voltage out-of-limit counters of each phase of the thyristors are initialized; A first control instruction is sent to the series side DC / AC power module in the UPQC to make the series side DC / AC power module output three-phase low voltage, and a turn-on instruction is simultaneously sent to the three-phase thyristors to make the three-phase thyristors turn on; During the turn-on function detection period, three-phase voltage sampling results output by the series side DC / AC power module are collected at a sampling period and subjected to voltage out-of-limit determination; If the voltage sampling result exceeds a first preset voltage threshold, the value of the turn-on voltage out-of-limit counter corresponding to the phase of the voltage sampling result is added by 1; If the count value of the turn-on voltage out-of-limit counter exceeds a first threshold, it is determined that the thyristor of the corresponding phase of the turn-on voltage out-of-limit counter does not normally turn on during the turn-on function detection period, and the bypass protection thyristor has a fault; If the count values of the turn-on voltage out-of-limit counters of the three-phase thyristors all do not exceed the first threshold, it is determined that the bypass protection thyristor has no fault.

5. The UPQC bypass protection thyristor self-checking method according to claim 4, characterized in that, Each phase of the thyristors is configured with a corresponding turn-off voltage accumulator; The off function detection of the bypass protection thyristor comprises: initializing off voltage accumulators of each phase thyristor; in the case of normal conduction of the bypass protection thyristor, making the series side DC / AC power module continuously output three-phase low voltage, and issuing off instruction to the three-phase thyristor to make the three-phase thyristor off; in the off function detection time period, collecting three-phase voltage sampling results output by the series side DC / AC power module according to the sampling period, and accumulating each phase voltage sampling result to the off voltage accumulator of the corresponding phase thyristor to obtain each phase voltage accumulation result; obtaining each phase voltage cycle average result according to the each phase voltage accumulation result; if the voltage cycle average result is lower than the second preset voltage threshold, the corresponding phase thyristor is not normally off, and the bypass protection thyristor has a fault; if each phase voltage cycle average result is not lower than the second preset voltage threshold, the bypass protection thyristor has no fault.

6. The UPQC bypass protection thyristor self-checking method according to claim 5, characterized in that, The continuous self-checking processing of the bypass protection thyristor comprises: when the voltage of the series side DC / AC power module of a certain phase continuously exceeds the third preset voltage threshold for 3 seconds during voltage limit management, detecting the low voltage of the series coupling transformer of the phase; 7. A UPQC bypass protection thyristor self-checking system, characterized in that, if the low voltage of the phase continuously is less than the preset voltage value for 5 ms, it is judged that the bypass protection thyristor of the phase is mis-conducted. It comprises: a primary self-checking processing module, configured to perform primary self-checking processing on the bypass protection thyristor before the series side DC / AC power module of the UPQC performs voltage limit management, and judge whether the bypass protection thyristor has a fault; a continuous self-checking processing module, configured to issue a voltage limit management working instruction to the series side DC / AC power module, and perform continuous self-checking processing on the bypass protection thyristor, and judge whether the bypass protection thyristor is mis-conducted, in response to the bypass protection thyristor having no fault; 8. The UPQC bypass protection thyristor self-checking system according to claim 7, characterized in that, a result processing module, configured to issue a shutdown instruction to the series side DC / AC power module in response to the bypass protection thyristor having a fault or the bypass protection thyristor being mis-conducted, and issue a voltage limit management working instruction to the series side DC / AC power module in response to the bypass protection thyristor having no fault and the bypass protection thyristor being not mis-conducted. The primary self-checking processing module comprises: a conduction function detection submodule, configured to perform conduction function detection on the bypass protection thyristor, and judge that the bypass protection thyristor has a fault if the bypass protection thyristor is not normally conducted; 9. The UPQC bypass protection thyristor self-checking system of claim 8, wherein, an off function detection submodule, configured to perform off function detection on the bypass protection thyristor if the bypass protection thyristor is normally conducted, judge that the bypass protection thyristor has no fault if the bypass protection thyristor is normally off, and judge that the bypass protection thyristor has a fault otherwise. The continuous self-checking processing module comprises: a detection submodule, configured to detect the low voltage of the series coupling transformer of the phase when the voltage of the series side DC / AC power module of a certain phase continuously exceeds the third preset voltage threshold for 3 seconds during voltage limit management; a mis-conduction judgment submodule, configured to judge that the bypass protection thyristor of the phase is mis-conducted if the low voltage of the phase continuously is less than the preset voltage value for 5 ms.

10. A computer-readable storage medium, characterized in that, The computer program stored in the computer readable storage medium realizes the UPQC bypass protection thyristor self-checking method of any one of claims 1-6 when executed.

Images