Power Conversion Equipment

Abstract

To provide an electric power conversion device that can safely stop the operation when an anomaly occurs in a communication channel.SOLUTION: An electric power conversion device relating to an embodiment of the present invention comprises: a power converter including multiple unit converters in series connection; and a control device for generating serial data including control data for each of the multiple unit converters on the basis of state data that represents each state of the multiple unit converters. The serial data includes first data distinct from the last serial data transmitted by the control device. Each of the multiple unit converters has first communication-anomaly detection means including: memorizing the last value of the first data of the serial data transmitted just before; receiving the serial data currently transmitted; and determining whether or not the serial data is abnormal on the basis of the last value and the current value of the first data of the serial data currently transmitted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD An embodiment of the present invention relates to a power conversion device. [Background technology]

[0002] There are power conversion devices that convert AC to DC or DC to AC. Modular multilevel converters (MMCs) are being put into practical use as a power conversion method that can achieve large capacity while being compact by using self-extinguishing semiconductor switching elements.

[0003] In an MMC, a large number of unit converters are mounted on the power converter, and because each unit converter handles high voltages, optical fiber cables are used to transmit data to the control device. If communication between the control device and unit converters were to be performed on a one-to-many basis, optical fiber cables would be required for each unit converter, resulting in high costs. To avoid this, the control device and each unit converter are sometimes connected in a daisy chain in a loop.

[0004] In a daisy-chained communication path, if an abnormality occurs in the communication path, data transfer is interrupted, and the power conversion device cannot continue to operate.

[0005] If a system in which data transfer is interrupted is left unattended, it may lead to a breakdown in the power converter. Therefore, when data transfer is interrupted due to an abnormality in the communication path, it is necessary to forcibly stop the operation of the power converter.

[0006] On the other hand, even if a signal to stop the power converter is sent via the communication path where the abnormality occurred, it is difficult to send the signal to all unit converters to stop them. If a separate communication path is prepared for abnormality, there are problems such as increased costs for the device, longer installation period for the device, and increased maintenance work. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2012-100398 A Summary of the Invention [Problem to be solved by the invention]

[0008] The embodiment provides a power conversion device that can safely stop operation when an abnormality occurs in a communication path. [Means for solving the problem]

[0009] A power conversion device according to an embodiment includes a power converter including a plurality of unit converters connected in series, and a control device that receives updated status data based on the status of each of the plurality of unit converters and generates and transmits serial data including control data for controlling the operation of each of the plurality of unit converters. The plurality of unit converters and the control device transfer the serial data via a communication path connected in a daisy chain. The serial data includes first data having a value for distinguishing the serial data currently transmitted by the control device from the serial data transmitted immediately before by the control device. The plurality of unit converters each have a first communication anomaly detection means that stores an immediately preceding value, which is a value of the first data of the immediately before transmitted serial data, receives the currently transmitted serial data, and determines whether or not the transfer of the currently transmitted serial data is abnormal based on the current value, which is a value of the first data of the currently transmitted serial data, and the immediately preceding value. The control device has a second communication anomaly detection means that stores the immediately preceding value and determines whether or not the transfer of the currently transmitted serial data is abnormal based on the current value and the immediately preceding value. When the first communication anomaly detection means and the second communication anomaly detection means determine that the transfer of the currently transmitted serial data received by themselves is abnormal, they each store the number of times that the transfer of the serial data has been determined to be abnormal. When the number of times that the transfer of the serial data has been determined to be abnormal reaches a predetermined value of 2 or more, the first communication anomaly detection means stops the operation of its own converter. Effect of the Invention

[0010] In this embodiment, a power conversion device that can safely stop operation when an abnormality occurs in a communication path is realized. [Brief description of the drawings]

[0011] [Figure 1] 1 is a block diagram illustrating a power conversion device according to an embodiment; [Diagram 2]2 is a block diagram illustrating a unit converter that is a part of a power conversion device according to an embodiment. FIG. [Diagram 3] 4 is a schematic diagram illustrating serial data transferred through a communication path of the power conversion device according to the embodiment; FIG. [Figure 4] 4 is an example of a flowchart for explaining an operation of a power conversion device according to an embodiment. [Diagram 5] FIG. 4 is a schematic block diagram for explaining the operation of a power conversion device of a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc. are not necessarily the same as in reality. Even when the same part is shown, the dimensions and ratios of each part may be different depending on the drawing. In this specification and each drawing, elements similar to those described above with reference to the previous drawings are given the same reference numerals and detailed description thereof will be omitted as appropriate.

[0013] FIG. 1 is a block diagram illustrating a power conversion device according to an embodiment. 1, a power conversion device 10 of the embodiment includes a power converter 20 and a control device 50. The power conversion device 10 is connected to an AC circuit 1 via AC terminals 21a to 21c. As in this example, the power conversion device 10 may be connected to the AC circuit 1 via a transformer 2. For example, the AC circuit 1 may be a power system including a three-phase or single-phase 50 Hz or 60 Hz AC power source, an AC load, and an AC transmission line.

[0014] The power conversion device 10 is connected to a DC circuit via DC terminals 21d and 21e. The DC circuit is, for example, a DC power system including a DC transmission line.

[0015] The power conversion device 10 is connected between the AC circuit 1 and the DC circuit, and converts an AC voltage into a DC voltage. The power conversion device 10 also converts a DC voltage into an AC voltage. The power conversion device 10 may perform unidirectional power conversion, or may perform bidirectional power conversion.

[0016] The power converter 20 includes arms 22 corresponding to each phase of the AC. When the AC circuit 1 is a three-phase AC as in this example, the power converter 20 includes six arms 22. Two arms 22 provided for each phase are connected in series between the DC terminals 21d and 21e.

[0017] A buffer reactor 24 is connected in series to each arm 22 connected in series between the DC terminals 21d and 21e.

[0018] The connection nodes of the buffer reactors 24 connected to the arms 22 on the high potential side and the low potential side corresponding to each phase are connected to the AC terminals 21a to 21c.

[0019] The arm 22 includes a plurality of unit converters 30 connected in series. It is assumed that n unit converters 30 are connected in series per arm 22, where n is an integer of 2 or more.

[0020] In this example, n unit converters 30 are connected in series to the arm 22 on the high potential side of the U phase, such as UP1, UP2, ... UPn, from the high potential side to the low potential side. n unit converters 30 are also connected in series to the arm 22 on the low potential side of the U phase, such as UN1, UN2, ... UNn, from the high potential side to the low potential side. Similarly, n unit converters 30 are connected in series to the arms 22 on the high potential side and low potential side of the V phase and W phase, respectively.

[0021] Each unit converter 30 includes a communication error detection section 32. The control device 50 includes a communication error detection section 52. Each unit converter 30 and the control device are daisy-chained in a loop shape via the communication error detection sections 32, 52.

[0022] In this example, optical fiber cables 60u to 60w are provided for the U to W phases, respectively. For example, for the U phase, the optical fiber cable 60u forms a daisy-chain loop in the order of the control device 50, the unit converters UP1, UP2, ... UPn, UN1, UN2, ... UNn, and the control device 50, and data is transferred in this order. Similarly, for the V and W phases, the optical fiber cables 60v and 60w daisy-chain the control device 50 and each unit converter 30, and data is transferred.

[0023] The daisy chain loop is not limited to the above, but all phases may be connected by one daisy chain loop, or a daisy chain loop may be formed for each arm 22. Also, the arm 22 may be divided into several parts, and a daisy chain loop may be formed for each divided part. In this way, the configuration of the daisy chain can be appropriately and arbitrarily set depending on the number of unit converters 30 in the arm 22, etc.

[0024] The control device 50 receives serial data DS from the unit converter 30 via the optical fiber cable. The serial data DS stores status data representing the status of each unit converter 30, as will be described later, for each unit converter 30. The control device 50 generates control data for each unit converter 30 based on the status data of each unit converter 30, generates new serial data DS storing the generated control data for each unit converter 30, and transmits it to the unit converter 30.

[0025] The serial data DS transmitted from the control device 50 is transferred to each unit converter 30 via the daisy-chain connection loop.

[0026] The configuration of the unit converter (hereinafter also referred to as a cell) 30 will be described. FIG. 2 is a block diagram illustrating a unit converter that is a part of the power conversion device. 2, the unit converter 30 includes terminals 31a and 31b. The unit converter 30 is electrically connected to other unit converters 30, etc., via the terminals 31a and 31b.

[0027] The cell 30 includes a communication anomaly detection unit 32, gate drive circuits 34a, 34b, switching elements 36a, 36b, and a capacitor 38. In addition to the above, the cell 30 includes a photoelectric conversion circuit that converts the received serial data of an optical signal into serial data DS of an electrical signal, and converts the serial data DS processed and updated in the cell 30 into an optical signal. In the following, to avoid complication, the cell 30 will be described as receiving, processing, and transferring the serial data DS of an electrical signal.

[0028] The cell 30 also includes a control circuit. The control circuit extracts and processes control data for itself from the serial data DS received by the cell 30, and writes status data representing its own status to update the serial data DS. The control data includes, for example, gate signal data for driving the switching elements 36a and 36b. The status data includes, for example, DC voltage data across the capacitor 38. The cell 30 also includes a power supply circuit that supplies power to various circuit functions including the communication anomaly detection unit 32, the gate drive circuits 34a and 34b, the photoelectric conversion circuit, and the control circuit. However, the photoelectric conversion circuit, the control circuit, the power supply circuit, and the like are not shown in FIG. 2.

[0029] The communication anomaly detection unit 32 inputs serial data DS transferred from another cell 30 or the control device 50, and if it determines that there is an anomaly in the transferred serial data DS, it generates and outputs a gate block (GB) signal. If the communication anomaly detection unit 32 determines that there is no anomaly in the transfer of the serial data DS, it outputs the serial data DS as is to the control circuit. The control circuit executes a predetermined process based on various data in the serial data DS, and transfers the updated serial data DS to another cell or the control device 50 upon completion of the process.

[0030] The gate drive circuits 34a and 34b are connected to the switching elements 36a and 36b, respectively. The switching elements 36a and 36b are connected in series. The gate drive circuit 34a is provided to drive the switching element 36a on the high potential side. The gate drive circuit 34b is provided to drive the switching element 36b on the low potential side.

[0031] The capacitor 38 is connected in parallel to the series circuit of the switching elements 36a and 36b. The high-potential side terminal 31a is connected to the connection node of the series circuit of the switching elements 36a and 36b. The low-potential side terminal 31b is connected to the low-potential side main terminal of the switching element 36b. The switching elements 36a and 36b are self-extinguishing semiconductor switching elements, such as IGBTs (Insulated Gate Bipolar Transistors). Thus, the terminal 31a is connected to the emitter terminal of the switching element 36a and the collector terminal of the switching element 36b, and the terminal 31b is connected to the emitter terminal of the switching element 36b.

[0032] The configuration of the communication error detection unit 32 will be described. The communication error detection unit 32 includes a data buffer 322 and a communication error detection circuit 326. The data buffer 322 temporarily stores the transferred serial data DS. The data buffer 322 includes a flag bit 324, and when new serial data DS is stored in the data buffer 322, the flag bit 324 becomes active.

[0033] The communication error detection circuit 326 is connected to the data buffer 322. The communication error detection circuit 326 monitors the state of the flag bit 324. When the communication error detection circuit 326 detects that the flag bit 324 has become active, it checks the data in a specific area of ​​the serial data DS stored in the data buffer 322. The communication error detection circuit 326 compares the value of the data in the specific area of ​​the serial data DS stored in the data buffer 322 immediately before with the value of the data in the specific area of ​​the serial data DS stored in the data buffer 322 due to the inversion of the flag bit 324.

[0034] If, for data in a specific area of ​​the serial data DS, the value of the previous data and the value of the current data are the same or do not satisfy a specified condition, the communication anomaly detection circuit 326 determines that there is a communication anomaly in the serial data DS, generates a GB signal, and outputs it to the gate drive circuits 34a, 34b.

[0035] If the immediately preceding data and the current data satisfy a predetermined condition, the communication error detection circuit 326 outputs a data processing permission command to the control circuit. Based on the data processing permission command, the control circuit starts processing the serial data DS currently stored in the data buffer 322. After completing the predetermined processing of the serial data DS, the control circuit transmits the serial data DS to another cell 30 or the control device 50.

[0036] The control device 50 has a communication anomaly detection unit 52, similar to the cell 30. The communication anomaly detection unit 52 is configured similarly to the communication anomaly detection unit 32 of the cell 30, and operates similarly. That is, for a specific area of ​​the serial data DS, the communication anomaly detection unit 52 compares the value of the current data with the value of the immediately preceding data, and if a predetermined condition is met, processes the serial data DS having the current data. If the communication anomaly detection unit 52 compares the value of the current data with the value of the immediately preceding data for a specific area of ​​the serial data DS and if a predetermined condition is not met, it stops processing the serial data DS and does not transmit the next serial data DS.

[0037] The configuration of the serial data DS will be described. FIG. 3 is a schematic diagram illustrating serial data transferred through a communication path of the power conversion device according to the embodiment. 3, the serial data DS stores predetermined data in a plurality of areas. The serial data DS includes heartbeat data (HB data) D0 and a plurality of data sets D1, D2, .... The HB data D0 is stored in the HB data area, and each of the data sets D1, D2, ... is stored in a predetermined data area.

[0038] The HB data D0 is, for example, 1-bit data. A different value is set to the HB data D0 each time the control device 50 generates serial data DS. For example, in the first serial data DS(1), "1" is set to the HB data D0, and in the second generated serial data DS(2), "0" is set to the HB data D0. Thereafter, "1" and "0" are alternately set to the HB data D0. The control device 50 sequentially transmits the serial data DS in which "1" and "0" are alternately set in the HB data field to the first cell 30.

[0039] The HB data D0 can be any suitable data, not limited to the above, by setting a condition for normal transfer of the serial data DS as a condition that a predetermined condition is satisfied between the current value and the immediately preceding value. For example, in addition to the above-mentioned 1-bit data, the HB data D0 may be multi-bit data, and the HB data D0 may be cell number data for identifying the cell 30. In either case, the predetermined condition is that the difference between the value of the current data and the value of the immediately preceding data is "1". The difference between the value of the current data and the value of the immediately preceding data may be "10" (binary "2"). The control device 50 sequentially transmits the serial data DS having the HB data D0 generated in the order of the cell numbers to the first cell in the order of the cell numbers.

[0040] The plurality of data sets D1, D2, ... are set in the same number as the number of cells 30 connected via the daisy-chained communication paths. As shown in Fig. 1, when 2xn cells 30 are daisy-chained with optical fiber cables 60, the serial data DS includes 2xn sets of data sets, for example, data set D1 includes data for cell UP1, data set D2 includes data for cell UP2, and so on.

[0041] Each data set may include cell number data, gate signal data, DC voltage data, etc. In this example, the first data set D1 includes a first cell number D11, gate signal data D12 for the first cell, and DC voltage data D13 detected at the first cell. The second data set D2 includes a second cell number D21, gate signal data D22 for the second cell number, and DC voltage data D23 detected at the second cell. Note that the gate signal data is preset by the control device 50, and the DC voltage data is updated with data detected at the corresponding cell.

[0042] The operation of the power conversion device 10 according to the embodiment will be described. FIG. 4 is an example of a flowchart for explaining the operation of the power conversion device according to the embodiment. In the following, a case will be described in which the control device 50 transmits serial data DS(i) generated for the i-th time, receives the j-th cell (j), and cannot receive the cell (j). The serial data DS(i) includes 1-bit HB data D0(i). In the example shown in FIG. 1, i=1 to 2×n, and j=1 to 2×n.

[0043] 4, in step S1, the communication error detection circuit 326 of cell (j) monitors whether or not the flag bit 324 is inverted. If the communication error detection circuit 326 of cell (j) detects an inversion of the flag bit 324, it determines that the serial data DS(i) has been properly received, and the communication error detection circuit 326 shifts the process to the next step S2. If an inversion of the flag bit 324 is not detected even after a preset time has elapsed, the communication error detection circuit 326 shifts the process to step S3.

[0044] In step S2, the communication error detection circuit 326 checks the HB data D0(i) of the serial data DS(i) in the data buffer 322.

[0045] In step S3, the communication error detection circuit 326 stores the number of times that it was unable to detect an inversion of the flag bit 324. If the stored number of times has not reached a preset number of times N, the communication error detection circuit 326 transitions the process to step S2. If the stored number of times has reached a preset number of times N, the communication error detection circuit 326 transitions the process to step S8. The number of times N is set to 2 or more, for example, N=10, in order to prevent the power converter 20 from frequently stopping due to erroneous detection of non-delivery of serial data, etc.

[0046] In step S4, the communication error detection circuit 326 compares the value of the HB data D0(i) with the value of the HB data D0(i-1) of the serial data DS(i-1) transmitted by the control device 50 immediately before the serial data DS(i). If the difference between the value of the current HB data D0(i) and the value of the previous HB data D0(i-1) is "1", the communication error detection circuit 326 determines that the cell (j) has received proper serial data DS(i) and transitions the process to the next step S5. If the difference between the value of the current HB data D0(i) and the value of the previous HB data D0(i-1) is "0", the communication error detection circuit 326 determines that the received serial data may not be proper and transitions the process to step S6.

[0047] In step S5, the communication anomaly detection circuit 326 outputs the serial data DS(i) to the control circuit. The control circuit extracts the data set Dj whose cell number data matches "j" from the serial data DS(i), and extracts and sets the gate signal data from the data set Dj. The communication anomaly detection circuit 326 writes the DC voltage data detected by itself into the DC voltage data area of ​​the data set Dj.

[0048] In step S6, the communication error detection circuit 326 stores the number of times the difference in the HB data value is "0". If the stored number of times has not reached the preset number of times N, the communication error detection circuit 326 transitions the process to step S5. If the stored number of times has reached the number of times N, the communication error detection circuit 326 transitions the process to step S8.

[0049] After processing step S5, the control circuit transfers the updated serial data DS(i) to the next cell (j+1) in step S7.

[0050] When the number of times stored in step S3 or step S6 reaches the number N, the communication anomaly detection circuit 326 generates a GB signal in step S8 and outputs it to the gate drive circuits 34a and 34b. This turns off the switching elements 36a and 36b of cell (j), and cell (j) enters the GB state and stops.

[0051] The serial data DS(i) is not transferred to the cell (j+1) that follows the cell (j), etc. Therefore, the cells after the cell (j+1) sequentially go through the steps described above to the GB state and stop.

[0052] Since the last cell (2×n) does not transfer the serial data DS(i) to the control device 50, the communication anomaly detection unit 52 of the control device 50 determines that there is a communication anomaly and does not transmit the next serial data DS(i+1) to the first cell (1). Therefore, the serial data DS(i+1) is not transferred to the cells after cell (1), and the power converters 20 sequentially enter the GB state and stop.

[0053] In this way, the power conversion device 10 of the embodiment can put all cells into the GB state and safely stop the power converter 20 if an abnormality such as a break occurs in the optical fiber cable that forms the communication path between each cell and the control device 50.

[0054] The effects of the power conversion device 10 according to the embodiment will be described in comparison with a power conversion device of a comparative example. FIG. 5 is a schematic block diagram for explaining the operation of a power conversion device of a comparative example. First, the configuration of a power conversion device of a comparative example will be described. As shown in Fig. 5, the power conversion device of the comparative example includes a power converter 1020 and a control device 1050. The power converter 1020 has cells 1030 connected in series. In Fig. 5, the configuration of one arm is shown, and the other arms are omitted. The power conversion device of the comparative example is provided with arms corresponding to the number of phases of the AC circuit to be connected, similar to the power conversion device 10 according to the embodiment shown in Fig. 1.

[0055] The cell 1030 has the same configuration as the cell 30 in the embodiment, except that the cell 1030 does not have the communication anomaly detection unit 32 of the cell 30 in the embodiment. The cells 1030 and the control device 1050 are daisy-chained with an optical fiber cable 60. Serial data generated by the control device 1050 is transferred between the cells 1030 via the optical fiber cable 60.

[0056] The control device 1050 has a communication error detection unit 1052. The communication error detection unit 1052 generates a GB signal when it is unable to receive serial data from the last cell 1030. An example of a case where the communication error detection unit 1052 is unable to receive serial data from the last cell 1030 is when the optical fiber cable 60 connecting the k-th cell 1030 and the k+1-th cell 1030 is cut. Therefore, the k+1-th and subsequent cells 1030 cannot receive or transfer the serial data. Therefore, the control device 1050 does not receive the serial data.

[0057] Meanwhile, since data cannot be sent or received due to a defect in the optical fiber cable 60 in the middle, if this state is left as it is, the DC voltage balance between the cells 1030 may be lost, which may cause a defect in the entire power converter 1020. Therefore, in the power conversion device of the comparative example, it is necessary to separately provide all the cells 1030 constituting the power converter 1020 and an optical fiber cable 1062 for transmitting GB signals.

[0058] The number of cells 1030 connected in series is determined by the voltage values ​​of the AC and DC circuits to which they are connected. If the number of cells 1030 increases, the number of optical fiber cables 1062 for transmitting GB signals also increases. This may increase the cost of the optical fiber cables 1062 and the labor and costs required for installing them.

[0059] In the power conversion device 10 according to the embodiment, all the cells 30 constituting the power converter 20 have the communication anomaly detection unit 32. Therefore, even if the serial data DS cannot be transferred due to a communication anomaly caused by a defect in the optical fiber cable 60, the power converter 20 can be safely and reliably stopped without providing a separate optical fiber cable for transmitting the GB signal.

[0060] In the power conversion device 10 according to the embodiment, when multiple communication abnormalities are detected, the GB signal is generated to stop the power converter 20, so that unnecessary stoppage due to erroneous detection or the like can be avoided.

[0061] In the above-mentioned specific example, a power conversion device that performs power conversion between AC voltage and DC voltage has been described. However, the present invention is not limited to this and can be applied to a reactive power compensation device that is connected to an AC system or the like and adjusts the reactive power of the AC system.

[0062] According to the embodiment described above, it is possible to realize a power conversion device that can safely stop operation when an abnormality occurs in the communication path.

[0063] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. In addition, the above-mentioned embodiments can be implemented in combination with each other. [Explanation of symbols]

[0064] 1...AC circuit, 2...transformer, 10...power conversion device, 20...power converter, 30...unit converter (cell), 32...communication anomaly detection section, 34a, 34b...gate drive circuit, 36a, 36b...switching element, 38...capacitor, 322...data buffer, 324...flag bit, 326...communication anomaly detection circuit

Claims

1. a power converter including a plurality of unit converters connected in series; a control device that receives status data updated based on the status of each of the plurality of unit converters, and generates and transmits serial data including control data for controlling the operation of each of the plurality of unit converters; Equipped with the plurality of unit converters and the control device transfer the serial data via a communication path connected in a daisy chain; the serial data includes first data having a value for distinguishing the serial data currently transmitted by the control device from the serial data previously transmitted by the control device; The plurality of unit converters include storing a previous value which is a value of the first data of the previously transmitted serial data; a first communication anomaly detection means for receiving the currently transmitted serial data and determining whether or not a transfer of the currently transmitted serial data is abnormal based on a current value, which is a value of the first data of the currently transmitted serial data, and the immediately preceding value; the control device has a second communication anomaly detection means for storing the immediately preceding value and determining whether or not a transfer of the currently transmitted serial data is abnormal based on the current value and the immediately preceding value; When the first communication anomaly detection means and the second communication anomaly detection means determine that the transfer of the currently transmitted serial data received by themselves is abnormal, the first communication anomaly detection means and the second communication anomaly detection means each store the number of times that the transfer of the serial data has been determined to be abnormal; The first communication anomaly detection means is a power conversion device that stops operation of its own converter when the number of times that it has determined that the transfer of the serial data is abnormal reaches a predetermined value of two or more.

2. The first communication anomaly detection means a data buffer for temporarily storing the serial data and having a flag bit when the serial data is stored; a communication error detection circuit that checks a value of the first data of the serial data when the flag bit is inverted; The power converter of claim 1 .

3. 3. The power conversion device according to claim 2, wherein the communication anomaly detection circuit generates a gate block signal to stop operation of its own converter when the number of times the serial data is determined to be abnormal reaches a predetermined value.

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