Interference signal filtering method and system suitable for nuclear power plant control rod position measurement

Abstract

The present invention provides a method and system for filtering interference signals suitable for nuclear power plant control rod position measurement, relating to the field of control rod signal processing technology. The purpose is to effectively filter interference signals from a control rod position detector in a simpler and more efficient manner, including continuously monitoring the voltage values ​​of an auxiliary coil and / or a measuring coil and obtaining an envelope value; identifying the starting point of the interference signal; if the starting point of the interference signal is identified, optimizing and updating the obtained envelope value starting from the starting point of the interference signal, and using the optimized and updated envelope value for rod position calculation; if the starting point of the interference signal is not identified, directly using the obtained envelope value for control rod position measurement. The present invention has the advantage of being able to identify and eliminate interference caused by control rod movement on the detector coil through a small amount of data processing, thereby improving the accuracy of rod position measurement.

Description

Technical Field

[0001] The present invention relates to the technical field of control rod signal processing, and in particular to an interference signal filtering method and system suitable for control rod position measurement in a nuclear power plant. Background Art

[0002] Nuclear power plants control power by changing the axial position of control rods within the reactor core. Real-time monitoring of the control rod position is essential during plant operation. Because the control rods move in conjunction with the drive rods, their position within the control rod travel sleeve can be monitored to determine their position within the reactor core. The drive rods, located at the center axis of the control rod travel sleeve, have a magnetic permeability significantly higher than that of air. This property can be exploited to measure the drive rod position using the principle of electromagnetic induction.

[0003] In existing technology, nuclear power plant rod position detectors are typically discrete coil encoded differential transformer detectors, consisting of a primary coil, an auxiliary coil, and a measuring coil. The primary coil is continuously wound to cover the entire travel of the control rod and is used to provide excitation for the detector. The auxiliary coil, consisting of two coils—a top coil and a bottom coil—is used to provide auxiliary signals. Rod position measurement is primarily achieved using the measuring coil. However, when the control rod moves, its drive mechanism generates strong electromagnetic interference, causing the detector coil output voltage to fluctuate. This interference signal affects the accuracy of rod position measurement. This interference signal is present in both the detector's measuring coil and the auxiliary coil, and can significantly affect the rod position detection results. Signal filtering typically requires monitoring a large amount of data, especially since a rod position detector can have dozens of coils. Monitoring the signals of each coil is a significant workload, resulting in high computational complexity and computational latency.

[0004] Therefore, it is necessary to design a method to effectively filter out the interference signal of the control rod position detector in a simpler and more efficient way. Summary of the Invention

[0005] The object of the present invention is to provide a method and system for filtering interference signals for control rod position measurement in a nuclear power plant, which can effectively filter the interference signals of the control rod position detector in a simpler and more efficient manner.

[0006] The embodiments of the present invention are achieved through the following technical solutions:

[0007] The present invention first provides a method for filtering interference signals applicable to position measurement of control rods in nuclear power plants. The control rods are provided with auxiliary coils and measuring coils, wherein the auxiliary coils include a bottom coil provided at the bottom of the control rods and a top coil provided at the top of the control rods. The method comprises the following steps:

[0008] Continuously monitoring the voltage value of the auxiliary coil and obtaining an envelope value;

[0009] Continuously monitoring the voltage value of the measuring coil and obtaining an envelope value;

[0010] identifying a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil;

[0011] If the starting point of the interference signal is identified, the auxiliary coil envelope value and / or the measuring coil envelope value obtained from the starting point of the identified interference signal are optimized and updated, and the optimized and updated envelope value is used to calculate the rod position;

[0012] If the starting point of the interference signal is not identified, the control rod position measurement is performed directly using the acquired auxiliary coil envelope value and / or measurement coil envelope value.

[0013] Preferably, the method for continuously monitoring the voltage value of the auxiliary coil and / or the measuring coil and obtaining the envelope value is:

[0014] Obtaining the voltage value of the auxiliary coil and / or the measuring coil

[0015] The envelope value is acquired based on the voltage value, where the envelope value adopts a peak value or an effective value.

[0016] Preferably, the method for identifying the starting point of the interference signal based on the envelope value of the auxiliary coil and / or the measuring coil is:

[0017] Reading the envelope value at the current moment;

[0018] Compare the envelope value at the current moment with the envelope value at the previous moment. If the envelope value at the current moment jumps and is higher than the envelope value at the previous moment by a difference greater than a preset difference threshold, the current moment is determined to be the starting point of the interference signal.

[0019] Preferably, the method for optimizing and updating the auxiliary coil envelope value and the measuring coil envelope value obtained from the starting point of identifying the interference signal is:

[0020] Starting from the starting point of the interference signal, within a duration t, the envelope value is updated to the envelope value at a moment before the starting point of the interference signal.

[0021] Preferably, the lower limit of the duration t is t lb for:

[0022] t lb =600ms;

[0023] Among them, ms represents the time unit milliseconds

[0024] Preferably, the upper limit of the duration t is t ub The method is:

[0025] Without limiting or using the control rod operating speed:

[0026]

[0027] Among them, v max is the maximum operating speed of the control rod, in steps per minute;

[0028] When using or limiting the control rod speed, the upper limit of t is t ub It is the interval time between two steps of the control rod operation.

[0029] Preferably, the maximum operating speed of the control rod is set to 72 steps / minute.

[0030] The present invention also provides an interference signal filtering system for nuclear power plant control rod position measurement, which is applied to any of the above-mentioned interference signal filtering methods for nuclear power plant control rod position measurement, comprising:

[0031] An envelope value acquisition module, configured to continuously monitor the voltage value of the auxiliary coil and acquire an envelope value, and continuously monitor the voltage value of the measuring coil and acquire an envelope value;

[0032] an interference signal identification module, configured to identify a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil;

[0033] an optimization and updating module, configured to optimize and update the auxiliary coil envelope value and / or the measuring coil envelope value obtained starting from the starting point of the identified interference signal when the starting point of the interference signal is identified;

[0034] The rod position measurement module is configured to calculate the rod position using the optimized and updated envelope value starting from the starting point of the interference signal when the starting point of the interference signal is identified, and directly measure the control rod position using the obtained envelope value when the starting point of the interference signal is not identified.

[0035] The technical solutions of the embodiments of the present invention have at least the following advantages and beneficial effects:

[0036] The present invention can monitor interference signals of auxiliary coils and / or measuring coils to determine the interference situation of the entire control rod, thereby reducing the workload and calculation amount of interference signal monitoring and helping to improve the efficiency of interference signal monitoring.

[0037] The present invention can accurately capture interference signals based on the auxiliary coil with as little data as possible, which can further improve the efficiency and reliability of interference signal monitoring;

[0038] After finding the interference signal, the present invention can more accurately estimate the possible existence time of the interference signal and optimize the detected envelope value at this stage, thereby eliminating the influence of the interference signal and improving the accuracy of rod position detection;

[0039] The technology of the present invention is easy to realize and can be widely applied to coding rod position detectors, thus being easy to popularize and implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of a method for filtering interference signals for controlling rod position measurement in a nuclear power plant, provided in Example 1 of the present invention;

[0041] Figure 2 Schematic diagram of the output of each coil group of the rod position detector in the lifting stage provided by Example 1 of the present invention;

[0042] Figure 3 Schematic diagram of the output envelope of each coil group of the rod position detector in the lifting stage provided by Example 1 of the present invention;

[0043] Figure 4 A partial schematic diagram of the output envelope of each coil group of the rod position detector in the lifting stage provided by Example 1 of the present invention;

[0044] Figure 5 Schematic diagram of the filtering effect of the moving rod interference signal of the output envelope of each group of coils of the rod position detector in the lifting stage provided by Example 1 of the present invention;

[0045] Figure 6 Schematic diagram of the output of each coil group of the rod position detector during the insertion phase provided by Example 1 of the present invention;

[0046] Figure 7 Schematic diagram of the output envelope of each coil group of the rod position detector during the insertion phase provided by Example 1 of the present invention;

[0047] Figure 8 A partial schematic diagram of the output envelope of each coil group of the rod position detector during the insertion phase provided by Example 1 of the present invention;

[0048] Figure 9 Schematic diagram of the effect of filtering out the moving rod interference signal from the output envelope of each group of coils of the rod position detector during the insertion phase provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0050] Example 1

[0051] This embodiment provides a method for filtering interference signals suitable for nuclear power plant control rod position measurement.

[0052] The control rod is provided with an auxiliary coil and a measuring coil. The auxiliary coil includes a bottom coil provided at the bottom of the control rod and a top coil provided at the top of the control rod. Figure 1 , including the following steps:

[0053] Continuously monitoring the voltage value of the auxiliary coil and obtaining an envelope value;

[0054] Continuously monitoring the voltage value of the measuring coil and obtaining an envelope value;

[0055] identifying a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil;

[0056] If the starting point of the interference signal is identified, the auxiliary coil envelope value and / or the measuring coil envelope value obtained from the starting point of the identified interference signal are optimized and updated, and the optimized and updated envelope value is used to calculate the rod position;

[0057] If the starting point of the interference signal is not identified, the control rod position measurement is performed directly using the acquired auxiliary coil envelope value and / or measurement coil envelope value.

[0058] This embodiment, targeting conventional rod position detectors, accurately identifies the moving rod interference signal by analyzing the characteristic points of the detector's output signal without changing the existing structure and operating mode. Based on this, it can filter out the effects of the interference signal, thereby improving the accuracy of rod position measurement. It is particularly noteworthy that, based on the solution of this embodiment, interference identification can be performed only on the auxiliary coil, only on the measuring coil, or both. After interference is identified through any method, the envelope value of any coil can be optimized and updated.

[0059] In this embodiment, the method for continuously monitoring the voltage value of the auxiliary coil and / or the measuring coil and obtaining the envelope value is:

[0060] Obtaining the voltage value of the auxiliary coil and / or the measuring coil

[0061] The envelope value is acquired based on the voltage value, where the envelope value adopts a peak value or an effective value.

[0062] As a preferred solution, the method for identifying the starting point of the interference signal based on the envelope value of the auxiliary coil and / or the measuring coil is:

[0063] Reading the envelope value at the current moment;

[0064] Compare the envelope value at the current moment with the envelope value at the previous moment. If the envelope value at the current moment jumps and is higher than the envelope value at the previous moment by a difference greater than a preset difference threshold, the current moment is determined to be the starting point of the interference signal.

[0065] Furthermore, the method for optimizing and updating the auxiliary coil envelope value and the measuring coil envelope value obtained from the starting point of identifying the interference signal is:

[0066] Starting from the starting point of the interference signal, within a duration t, the envelope value is updated to the envelope value at a moment before the starting point of the interference signal.

[0067] As a preferred solution of this embodiment, the lower limit of the duration t is t lb for:

[0068] t lb =600ms;

[0069] Among them, ms represents the time unit milliseconds

[0070] Based on the above, the upper limit of the duration t is t ub The method is preferably:

[0071] Without limiting or using the control rod operating speed:

[0072]

[0073] Among them, v max is the maximum operating speed of the control rod, in steps per minute;

[0074] When using or limiting the control rod speed, the upper limit of t is t ub It is the interval time between two steps of the control rod operation.

[0075] Furthermore, the maximum operating speed of the control rod is set to 72 steps per minute.

[0076] Specifically, when the control rod speed is not limited or used, the value of t ranges from 600ms to 833ms. When the control rod speed is used or limited, the upper limit of t is the interval between two control rod steps.

[0077] In this embodiment, the rod position detector has multiple groups of measuring coils in addition to the auxiliary coils. This embodiment reduces the monitoring of each coil and relies on the auxiliary coils to identify interference signals. The basis and implementation case results are as follows:

[0078] Assume there are 5 sets of measuring coils, namely measuring coils AE;

[0079] For the promotion phase, see Figure 2 ,This figure is a schematic diagram of the output of each group of coils of the rod position detector in the lifting stage, Figure 2 From top to bottom, the six waveform curves are, in order, the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. It can be seen from the figure that the auxiliary coil output is stable and does not change with the position of the control rod. The interference signal received by the moving rod is relatively consistent and easy to identify. Except for the auxiliary coil, the interference signal strength received by the measuring coils A, B, C, D, and E decreases in turn. The interference received by the moving rod is synchronized with the auxiliary coil in time. The interference signals received by C, D, and E are very small or basically not interfered with, making them difficult to identify. For a schematic diagram of the output envelope of each group of coils of the rod position detector during the lifting phase, please refer to Figure 3 , the six waveform curves from top to bottom are Figure 2 The effective value envelopes of the corresponding curves are the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. From the figure, it can be found that the auxiliary coil envelopes show regular jump characteristics, and the jump points are the moving rod interference points. For a partial schematic diagram of the output envelopes of each group of coils of the rod position detector during the lifting stage, please refer to Figure 4 , the six waveform curves from top to bottom are Figure 3 The partial expansion diagram of the effective value envelope curve is respectively the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. From the figure, it can be found that the auxiliary coil envelope moving rod interference point signal shows a sudden jump and then drops back to the original level. See the schematic diagram of the moving rod interference signal filtering effect of the output envelope of each group of coils of the rod position detector during the lifting stage. Figure 5 , the six waveform curves from top to bottom are Figure 3The schematic diagram after the effective value envelope identifies and filters out the moving rod interference signal is as follows: the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. It can be seen from the figure that after filtering out the moving rod interference signal, the moving rod interference signal disappears, and each measuring coil maintains the original curve trend.

[0080] For the insertion phase, see Figure 6 , this figure is a schematic diagram of the output of each group of coils of the rod position detector during the insertion phase. Similarly, the six waveform curves from top to bottom are, the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. It can be found from the figure that the output of the auxiliary coil is stable and does not change with the change of the control rod position, and the interference signal received by the moving rod is relatively consistent and easy to identify. Except for the auxiliary coil, the interference signal intensity received by the measuring coils A, B, C, D, and E decreases in turn, and the interference received by the moving rod is synchronized with the auxiliary coil in time, and the interference signals received by C, D, and E are very small or basically not interfered with, making them difficult to identify. For a schematic diagram of the output envelope of each group of coils of the rod position detector during the insertion phase, please refer to Figure 7 , the six waveform curves from top to bottom are Figure 6 The effective value envelope of the curves are the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. From the figure, it can be found that the auxiliary coil envelope shows a regular jump feature, and the jump point is the moving rod interference point. For a partial schematic diagram of the output envelope of each group of coils of the rod position detector during the insertion stage, please refer to Figure 8 , the six waveform curves from top to bottom are Figure 7 The partial expansion diagram of the effective value envelope curve shows the auxiliary coil curve, measurement coil A curve, measurement coil B curve, measurement coil C curve, measurement coil D curve, and measurement coil E curve. From the figure, it can be seen that the auxiliary coil envelope moving rod interference point signal shows a sudden jump and then drops back to the original level. For the schematic diagram of the output envelope of each group of coils of the rod position detector during the insertion phase and the effect of filtering out the moving rod interference signal, please refer to Figure 9 , the six waveform curves from top to bottom are Figure 6 The schematic diagram after the effective value envelope identifies and filters out the moving rod interference signal is as follows: the auxiliary coil curve, the measuring coil A curve, the measuring coil B curve, the measuring coil C curve, the measuring coil D curve, and the measuring coil E curve. It can be seen from the figure that after filtering out the moving rod interference signal, the moving rod interference signal disappears, and each measuring coil maintains the original curve trend.

[0081] When operating the above case based on the technical solution of this embodiment, the specific operation method is as follows:

[0082] The fundamental waves of the detector auxiliary coils and each group of measuring coils are all 50Hz sine waves, so first, calculate the effective value of the waveform of each coil (auxiliary coil and measuring coil). Since the fundamental wave is 50Hz, it can be calculated every 20ms. From the results, it can be seen that the characteristics of the moving rod interference signal received by the auxiliary coil of the rod position detector in the nuclear power plant reactor are used to identify it, and then the moving rod interference signal received by each measuring coil is filtered out, thereby improving the accuracy of the rod position measurement. In particular, it can be seen that whether it is lifting or inserting, the moving rod interference signal generated by the auxiliary coil first presents an upward jump feature, and the waveform recovery changes of lifting and insertion after the jump are slightly different. The method of this embodiment uses the waveform jump feature to judge the lifting and insertion of the rod, so it is not affected by the difference in waveform recovery.

[0083] In this case, when comparing envelope values ​​at two consecutive moments, the two consecutive RMS values ​​calculated for the auxiliary coil are compared. The previous RMS value is subtracted from the latter. If the difference is greater than a preset value (the preset value is determined based on the specific output of the detector, and in this case, the preset value is 0.5V), the auxiliary coil is considered to have begun to be disturbed by the moving rod. Otherwise, the auxiliary coil is considered to have not been disturbed by the moving rod. This is the identification of moving rod interference.

[0084] Based on whether the auxiliary coil is interfered with by the moving rod, the following two processes are performed:

[0085] If it is determined that there is no interference from the moving rod, that is, the starting point of the interference signal is not identified, the calculated effective value of the measuring coil is directly used to perform the next step of measuring rod position calculation;

[0086] If it is determined that there is interference from the moving rod, the effective value of the measuring coil just before the moving rod interference occurs is used to calculate the measuring rod position, and this value is used continuously for a period of time (the duration is set to 0.8s in this embodiment) until the duration is exceeded, and then the first step is restored to calculate the effective value of each group of coils and the moving rod interference judgment process.

[0087] From the processing effects of the enhancement and insertion in this case, it can be seen that after the processing scheme of this embodiment is applied to this case, the original change trend of the waveform of each measuring coil is not affected, and the interference clutter of the moving rod is filtered out, which can be better used for the subsequent calculation of the measurement rod position.

[0088] Example 2

[0089] In order to solve the above problems, the present invention also provides an interference signal filtering system applicable to nuclear power plant control rod position measurement, which is applied to any of the above-mentioned interference signal filtering methods applicable to nuclear power plant control rod position measurement, comprising:

[0090] An envelope value acquisition module, configured to continuously monitor the voltage value of the auxiliary coil and acquire an envelope value, and continuously monitor the voltage value of the measuring coil and acquire an envelope value;

[0091] an interference signal identification module, configured to identify a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil;

[0092] an optimization and updating module, configured to optimize and update the auxiliary coil envelope value and / or the measuring coil envelope value obtained starting from the starting point of the identified interference signal when the starting point of the interference signal is identified;

[0093] The rod position measurement module is configured to calculate the rod position using the optimized and updated envelope value starting from the starting point of the interference signal when the starting point of the interference signal is identified, and directly measure the control rod position using the obtained envelope value when the starting point of the interference signal is not identified.

[0094] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for filtering interference signals for position measurement of control rods in nuclear power plants, wherein the control rods are provided with auxiliary coils and measuring coils, wherein the auxiliary coils include a bottom coil provided at the bottom of the control rods and a top coil provided at the top of the control rods, characterized in that: The following steps are involved: Continuously monitoring the voltage value of the auxiliary coil and obtaining an envelope value; Continuously monitoring the voltage value of the measuring coil and obtaining an envelope value; identifying a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil; If the starting point of the interference signal is identified, the auxiliary coil envelope value and / or the measuring coil envelope value obtained from the starting point of the identified interference signal are optimized and updated, and the optimized and updated envelope value is used to calculate the rod position; If the starting point of the interference signal is not identified, directly using the obtained auxiliary coil envelope value and / or measuring coil envelope value to measure the control rod position; The method for identifying the starting point of the interference signal based on the envelope value of the auxiliary coil and / or the measuring coil is: Reading the envelope value at the current moment; Comparing the envelope value at the current moment with the envelope value at the previous moment, if the envelope value at the current moment jumps up and is higher than the envelope value at the previous moment by a difference greater than a preset difference threshold, determining that the current moment is the starting point of the interference signal; The method for optimizing and updating the auxiliary coil envelope value and the measuring coil envelope value obtained from the starting point of the interference signal identification is: Starting from the starting point of the interference signal, within a duration t, the envelope value is updated to the envelope value at a moment before the starting point of the interference signal.

2. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 1, characterized in that: The method for continuously monitoring the voltage value of the auxiliary coil and / or the measuring coil and obtaining the envelope value is: Obtaining a voltage value of the auxiliary coil and / or the measuring coil; The envelope value is acquired based on the voltage value, where the envelope value adopts a peak value or an effective value.

3. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 1, characterized in that: The lower limit of the duration t is t lb for: t lb =600ms; Here, ms represents the time unit milliseconds.

4. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 3, characterized in that: The upper limit of the duration t is t ub The method is: Without limiting or using the control rod operating speed: Among them, v max is the maximum operating speed of the control rod, in steps per minute; When using or limiting the control rod speed, the upper limit of t is t ub It is the interval time between two steps of the control rod operation.

5. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 4, characterized in that: The maximum operating speed of the control rods is set to 72 steps / minute.

6. An interference signal filtering system for nuclear power plant control rod position measurement, applied to the interference signal filtering method for nuclear power plant control rod position measurement according to any one of claims 1 to 5, characterized in that: include: An envelope value acquisition module, configured to continuously monitor the voltage value of the auxiliary coil and acquire an envelope value, and continuously monitor the voltage value of the measuring coil and acquire an envelope value; an interference signal identification module, configured to identify a starting point of an interference signal based on an envelope value of the auxiliary coil and / or the measuring coil; an optimization and updating module, configured to optimize and update the auxiliary coil envelope value and / or the measuring coil envelope value obtained starting from the starting point of the identified interference signal when the starting point of the interference signal is identified; The rod position measurement module is configured to calculate the rod position using the optimized and updated envelope value starting from the starting point of the interference signal when the starting point of the interference signal is identified, and directly measure the control rod position using the obtained envelope value when the starting point of the interference signal is not identified.

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