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

Abstract

The invention provides an interference signal filtering method and system suitable for nuclear power station control rod position measurement, relates to the technical field of control rod signal processing, and aims to effectively filter interference signals of a rod position detector of a control rod in a simpler and more efficient manner. Comprising the following steps: continuously monitoring a voltage value of an auxiliary coil and / or a measuring coil and acquiring an envelope value; identifying a starting point of the interference signal; if the starting point of the interference signal is recognized, optimizing and updating the obtained envelope value from the starting point of the interference signal, and carrying out rod position calculation by adopting the optimized and updated envelope value; and if the starting point of the interference signal is not identified, directly adopting the obtained envelope value to measure the position of the control rod. The method has the advantages that the interference of the control rod action on the detector coil can be identified and eliminated through a small amount of data processing, so that the accuracy of rod position measurement is improved.

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 nuclear power plant control rod position measurement. Background Art

[0002] Nuclear power plants control power by changing the axial position of control rods in the reactor core. The position of control rods needs to be monitored in real time during power plant operation. Since the control rods move together with the drive rods, the position of the control rods in the reactor core can be obtained by monitoring the position of the drive rods in the control rod travel sleeve. The drive rod is located at the central axis of the control rod travel sleeve, and its magnetic permeability is significantly higher than that of air. The measurement of the drive rod position can be achieved by using this characteristic and the principle of electromagnetic induction.

[0003] In the prior art, the rod position detector of a nuclear power plant is usually a discrete coil encoding differential transformer detector, which consists of a primary coil, an auxiliary coil and a measuring coil. The primary coil is continuously wound to cover the entire stroke of the control rod and is used to provide excitation for the detector. The auxiliary coil consists of two coils, the top coil and the bottom coil. The driving rod will never enter the top coil and will never leave the bottom coil, which is used to provide auxiliary signals. The rod position measurement is mainly achieved by the measuring coil. However, when the control rod moves, its driving mechanism will generate strong electromagnetic interference, causing the output voltage of the detector coil to fluctuate up and down, and the interference signal affects the correctness of the rod position measurement. The interference signal exists in both the detector measuring coil and the auxiliary coil, and the interference signal may have a great impact on the result of the rod position detection. Usually, signal filtering requires monitoring of a large amount of data, especially the coils of the rod position detector can be as many as dozens, and monitoring the signals of each coil is a relatively large workload, which is easy to cause large calculation amount and high calculation delay.

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

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

[0006] The embodiments of the present invention are implemented by the following technical solutions:

[0007] The present invention first provides an interference signal filtering method applicable to the position measurement of a control rod of a nuclear power plant, wherein the control rod is provided with an auxiliary coil and a measuring coil, wherein the auxiliary coil comprises a bottom coil arranged at the bottom of the control rod and a top coil arranged at the top of the control rod, and 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 acquired auxiliary coil envelope value and / or measuring coil envelope value is directly used to measure the control rod position.

[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] Read the envelope value at the current moment;

[0018] The envelope value at the current moment is compared with the envelope value at the previous moment. If the envelope value at the current moment jumps up and the difference between the envelope value at the previous moment and that at the previous moment is 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 / minute;

[0028] When the control rod speed is used or limited, the upper limit of t is t ub It is the interval time between two-step operation of the control rod.

[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 applicable to nuclear power plant control rod position measurement, which is applied to any one of the above-mentioned interference signal filtering methods applicable to nuclear power plant control rod position measurement, comprising:

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

[0032] An interference signal identification module, used to identify the starting point of the interference signal based on the 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] A rod position measurement module is used to use the optimized and updated envelope value to calculate the rod position when the starting point of the interference signal is identified, and to directly use the acquired envelope value to measure the control rod position when the starting point of the interference signal is not identified.

[0035] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects:

[0036] The present invention can monitor interference signals for 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, and 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 schematic flow chart of a method for filtering interference signals for measuring the position of control rods in a nuclear power plant provided in Example 1 of the present invention;

[0041] Figure 2 A schematic diagram of the output of each group of coils of the rod position detector in the lifting stage provided in Example 1 of the present invention;

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

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

[0044] Figure 5 A 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 in Example 1 of the present invention;

[0045] Figure 6 A schematic diagram of the output of each group of coils of the rod position detector in the insertion phase provided by Example 1 of the present invention;

[0046] Figure 7 A schematic diagram of the output envelope of each group of coils of the rod position detector in the insertion phase provided in Example 1 of the present invention;

[0047] Figure 8 A partial schematic diagram of the output envelope of each group of coils of the rod position detector in the insertion stage provided in Example 1 of the present invention;

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

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 here can be arranged and designed in various different configurations.

[0050] Example 1

[0051] This embodiment provides a method for filtering interference signals suitable for measuring the position of control rods in nuclear power plants.

[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 acquired auxiliary coil envelope value and / or measuring coil envelope value is directly used to measure the control rod position.

[0058] This embodiment is aimed at the traditional rod position detector. Without changing the existing structure and operation mode, by analyzing the characteristic points of the detector output signal, it can accurately identify the moving rod interference signal, and based on this, filter out the influence of the interference signal, thereby improving the accuracy of the rod position measurement. It is particularly noted that based on the scheme of this embodiment, interference identification can be performed only on the auxiliary coil, or only on the measuring coil, or both. After the interference is identified through any means, 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] Read the envelope value at the current moment;

[0064] The envelope value at the current moment is compared with the envelope value at the previous moment. If the envelope value at the current moment jumps up and the difference between the envelope value at the previous moment and that at the previous moment is 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 / minute;

[0074] When the control rod speed is used or limited, the upper limit of t is t ub It is the interval time between two-step operation of the control rod.

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

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

[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 the interference signal. 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 during the lifting stage, Figure 2 From top to bottom, the six waveform curves are, 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. It can be seen from the figure that the output of the auxiliary coil is stable and does not change with the position of the control rod, and 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, and the moving rod interference 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 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, refer to Figure 4 , the six waveform curves from top to bottom are Figure 3 The partial expansion diagram of the effective value envelope is the auxiliary coil curve, measuring coil A curve, measuring coil B curve, measuring coil C curve, measuring coil D curve, and 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 filtering effect of the moving rod interference signal of each group of coil output envelope of the rod position detector in the lifting stage for details. 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 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 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, 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. 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 successively, 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. It can be found from the figure that the auxiliary coil envelope shows a regular jump feature, and the jump point is the moving rod interference point. Figure 8 , the six waveform curves from top to bottom are Figure 7 The partial expansion diagram of the effective value envelope curve is 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. The schematic diagram of the moving rod interference signal filtering effect of each group of coil output envelopes of the rod position detector during the insertion stage is shown in Fig. 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 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 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 the technical solution of this embodiment is used in the above case, the specific operation method is as follows:

[0082] The fundamental waves of the detector auxiliary coils and each group of measuring coils are 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 the envelope values ​​at two consecutive moments, the effective values ​​calculated by the auxiliary coil twice are compared, and the latter effective value is subtracted from the previous effective value. If the difference is greater than the preset value (the preset value needs to be determined according to the specific output of the detector, and the preset value in this case is 0.5V), it is considered that the auxiliary coil has begun to be disturbed by the moving rod, otherwise it is considered that the auxiliary coil has not been disturbed by the moving rod. This is the identification of moving rod interference.

[0084] According to whether the auxiliary coil is interfered by the moving rod, the following two processes are performed respectively:

[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 values ​​of each group of coils and the moving rod interference judgment process.

[0087] From the processing effect of lifting and inserting 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 each measuring coil waveform 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 interference signal filtering methods applicable to nuclear power plant control rod position measurement, including:

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

[0091] An interference signal identification module, used to identify the starting point of the interference signal based on the 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] A rod position measurement module is used to use the optimized and updated envelope value to calculate the rod position when the starting point of the interference signal is identified, and to directly use the acquired envelope value to measure the control rod position when the starting point of the interference signal is not identified.

[0094] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope 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, the acquired auxiliary coil envelope value and / or measuring coil envelope value is directly used to measure the control rod position.

2. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 1 is 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: Acquiring 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 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: Read the envelope value at the current moment; The envelope value at the current moment is compared with the envelope value at the previous moment. If the envelope value at the current moment jumps up and the difference between the envelope value at the previous moment and that at the previous moment is greater than a preset difference threshold, the current moment is determined to be the starting point of the interference signal.

4. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 1, characterized in that: 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.

5. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 4 is characterized in that: The lower limit of the duration t is t lb for: t lb =600ms; Here, ms represents the time unit in milliseconds.

6. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 5, characterized in that: The upper limit value 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 / minute; When the control rod speed is used or limited, the upper limit of t is t ub It is the interval time between two-step operation of the control rod.

7. The interference signal filtering method for nuclear power plant control rod position measurement according to claim 6, characterized in that: The maximum operating speed of the control rods is set at 72 steps / minute.

8. An interference signal filtering system for nuclear power plant control rod position measurement, applied to an interference signal filtering method for nuclear power plant control rod position measurement as claimed in any one of claims 1 to 7, characterized in that: include: An envelope value acquisition module, used to continuously monitor the voltage value of the auxiliary coil and acquire the envelope value and to continuously monitor the voltage value of the measuring coil and acquire the envelope value; An interference signal identification module, used to identify the starting point of the interference signal based on the 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; A rod position measurement module is used to use the optimized and updated envelope value to calculate the rod position when the starting point of the interference signal is identified, and to directly use the acquired envelope value to measure the control rod position when the starting point of the interference signal is not identified.

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