An anti-interference method for full-stroke rod position measurement in pressurized water reactors based on Gray code.

Abstract

This invention belongs to the field of pressurized water reactor (PWR) rod position measurement technology, specifically relating to an anti-interference method for full-stroke rod position measurement in a PWR based on Gray code. The method includes setting a sampling time interval between two rod position calculations for the Gray code tuning results and the A / D conversion results of the Gray code position conditioning signals, based on a multiple of the time required for the control rod to move one mechanical step; initiating the current rod position measurement and sampling the tuning results and A / D conversion results of the conditioning signals for each Gray code position; determining the rod position interval for this measurement based on the Gray code tuning state sampled; and calculating the specific rod position for this measurement based on the A / D conversion results of the Gray code conditioning signals sampled. The beneficial effect is that, during the full-stroke rod position calculation based on Gray code, by setting a certain amount of rod position mechanical step overlap for the rod position interval corresponding to any Gray code state, the difference in the Gray code position conditioning signals of each Gray code position in the Gray code signal processing component across the entire control rod stroke is eliminated.

Description

Technical Field

[0001] This invention belongs to the field of pressurized water reactor rod position measurement technology, specifically relating to an anti-interference method for full-stroke rod position measurement of pressurized water reactors based on Gray code. Background Technology

[0002] Pressurized water reactors (PWRs) control reactivity by moving control rods containing neutron absorbers within the reactor core, ensuring safe and stable operation under set conditions. The rod position measurement system provides the actual position display of all control rod groups, serving as input data for core safety design, operator monitoring, core operation tracking, and refueling design for subsequent cycles. The Gray code-based full-stroke rod position measurement technology for PWRs first preliminarily determines the control rod position interval (e.g., 7 or 8 machine step intervals) based on five-bit (or six-bit) Gray code tuning results. Then, by sampling and analyzing the conditioning output signals of each Gray code bit, it accurately calculates the rod position measurement result with a full-stroke uncertainty of ±1 step within that interval. This method has the following two interference factors that may lead to distortion of the rod position measurement results:

[0003] (1) Due to limitations in the manufacturing process of the rod position detector and the design hysteresis of the Gray code tuning circuit, there may be a certain amount (e.g., 2 machine steps) of deviation between the rod position interval corresponding to any Gray code state and the theoretical value. This deviation will lead to an error in the rod position interval positioning, which is the premise for accurate calculation of the rod position based on the sampling and analysis of the output signal of each Gray code position conditioning. The final rod position calculation result may have a maximum deviation of one rod position interval theoretical value.

[0004] (2) During the movement of the control rod, the strong alternating drive current (usually tens of amperes) introduces certain interference into the secondary of the rod position detector, causing the sampling results of each Gray code position conditioning output signal to differ from the sampling results when the control rod is stationary. This introduces a large deviation in the accurate calculation of the rod position through the results of each Gray code position conditioning output signal, resulting in distortion of the rod position measurement results during the movement of the control rod. Summary of the Invention

[0005] The purpose of this invention is to provide an anti-interference method for full-stroke rod position measurement of pressurized water reactors based on Gray code. By setting a certain overlap between the rod position intervals corresponding to the Gray code states, the validity of the rod position results calculated for each sampling is judged according to the control rod movement model, so that the full-stroke rod position measurement results based on Gray code are correct and valid.

[0006] The technical solution of the present invention is as follows: A method for anti-interference measurement of full-stroke rod position in a pressurized water reactor based on Gray code, comprising the following steps:

[0007] Step 1: Control the time required for the control bar to move one mechanical step by a certain multiple, and set the sampling time interval between the two bar position calculations for the Gray code tuning results and the A / D conversion results of the conditioning signals of each Gray code position;

[0008] Step 2: Start the current bar position measurement and sample the tuning results of each Gray code position and the A / D conversion results of the conditioning signal;

[0009] Step 3: Determine the rod position interval for this measurement based on the Gray code setting state of the current sampling;

[0010] Step 4: Calculate the specific rod position for this measurement based on the A / D conversion result of the Gray code conditioning signal sampled this time;

[0011] Step 5: Compare the calculated rod position result of this measurement with the previous valid calculated rod position result;

[0012] Step 6: If the deviation between the calculated rod position result of the current measurement and the previous valid calculated rod position result is greater than +1, 0, -1 or -7, then the current measurement result is determined to be valid, and the rod position display is updated;

[0013] Step 7: If the deviation between the calculated rod position result of the current measurement and the previous valid calculated rod position result is not greater than +1, 0, -1 or -7, the current measurement result is determined to be invalid, and the previous valid calculated rod position result is used to replace the current rod position calculation result, and the rod position display is updated.

[0014] Step 8: The measurement of the rod position is now complete;

[0015] Step 9: Update the rod position measurement display.

[0016] Step 1 further includes expanding the bar position interval corresponding to the Gray code tuning state, so that the overlap between the bar position intervals corresponding to two adjacent Gray code tuning states is increased.

[0017] The overlap is at least 3 machine steps.

[0018] In step 1, a certain multiple is 0.8 or higher.

[0019] The beneficial effects of this invention are as follows: In the full-stroke rod position calculation process based on Gray code, this invention eliminates the influence of differences in the Gray code position conditioning signals of each Gray code position during the full stroke of the control rod by setting a certain rod position mechanical step overlap amount for the rod position interval corresponding to any Gray code state; it determines that a sampling period of less than the time required for the control rod to move one step is used for sampling the Gray code position conditioning signals and calculating the rod position, and performs validity judgment on the rod position calculation results to eliminate electrical interference during the movement of the control rod, thereby improving the accuracy and stability of the rod position measurement results. Attached Figure Description

[0020] Figure 1 The flowchart of an anti-interference method for full-stroke rod position measurement of a pressurized water reactor based on Gray code provided by the present invention;

[0021] Figure 2 The deviation curve (upward) of the full-stroke Gray code tuning results for the simulated output signal of the SA1.4 rod position detector;

[0022] Figure 3 The deviation curve (downward) of the full-stroke Gray code tuning results for the simulated output signal of the SA1.4 rod-position detector;

[0023] Figure 4 The deviation curve is shown for the full-stroke Gray code tuning result of the simulated output signal of the SA1.4 rod position detector. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] To address the potential deviation between the bar position interval corresponding to any Gray code state and the theoretical value, the influence of the difference in conditioning signals of each Gray code bit in the Gray code signal processing component on the bar position calculation result can be eliminated by expanding the bar position interval corresponding to the Gray code state (e.g., extending it by 3 machine steps to each end) so that the bar position intervals corresponding to two adjacent Gray code states overlap (e.g., overlapping by 3 machine steps).

[0026] The solution to the discrepancy between the sampling results of the Gray code conditioned signals during control rod movement and those when the control rod is stationary is to model the movement of the pressurized water reactor control rods. A sampling period is defined as the time required for the control rod to move one step. The difference between the calculated rod position after each sampling and the previous calculation satisfies the following rules: +1 steps indicate the control rod is moving upwards, 0 steps indicate the control rod is stationary, -1 step indicates the control rod is moving downwards, and a certain number of steps greater than negative (e.g., -7 steps) indicate the control rod is falling. Calculation results that satisfy these rules are considered valid, and the rod position measurement display is updated. Measurement results that do not satisfy these rules are considered errors caused by electrical interference (such as the introduction of alternating drive current during control rod movement), and the current rod position calculation result is invalid. The rod position measurement display retains the previous valid calculation result.

[0027] like Figure 1 As shown, an anti-interference method for full-stroke rod position measurement in a pressurized water reactor based on Gray code includes the following steps:

[0028] Step 1: Set the sampling time interval for the Gray code tuning result and the A / D conversion result of each Gray code position conditioning signal to be calculated twice, with the control rod moving one mechanical step time not exceeding (e.g., 0.8 times) the time required.

[0029] Based on the correspondence between the Gray code state and the bar position in the bar position measurement system, the bar position interval corresponding to the Gray code setting state is expanded (e.g., extended by 3 machine steps at each end) so that the bar position intervals corresponding to two adjacent Gray code setting states overlap by a certain amount (e.g., overlap by 3 machine steps).

[0030] Step 2: Start the current bar position measurement and sample the tuning results of each Gray code position and the A / D conversion results of the conditioning signal;

[0031] Step 3: Determine the rod position interval for this measurement based on the Gray code setting state of the current sampling;

[0032] Step 4: Calculate the specific rod position for this measurement based on the A / D conversion result of the Gray code conditioning signal sampled this time;

[0033] Step 5: Compare the calculated rod position result of this measurement with the previous valid calculated rod position result;

[0034] Step 6: If the deviation between the calculated rod position result of the current measurement and the previous valid calculated rod position result is greater than +1, 0, -1 or -7, then the current measurement result is determined to be valid, and the rod position display is updated;

[0035] Step 7: If the deviation between the current calculated rod position result and the previous valid calculated rod position result is not +1, 0, -1 or -7 (adjustable according to the rod control and rod position system design of the unit), the current measurement result is determined to be invalid, and the previous valid calculated rod position result is used to replace the current rod position calculation result and update the rod position display.

[0036] Step 8: The measurement of the rod position is now complete;

[0037] Step 9: Update the rod position measurement display.

Claims

1. An anti-interference method for full-stroke rod position measurement in a pressurized water reactor based on Gray code, characterized in that, Includes the following steps: Step 1: Control the time required for the control bar to move one mechanical step by a certain multiple, set the sampling time interval for the bar position calculation to the Gray code tuning result, and the sampling time interval for the bar position calculation to the Gray code position conditioning signal A / D conversion result; Step 2: Start the current bar position measurement and sample the tuning results of each Gray code position and the A / D conversion results of the conditioning signal; Step 3: Determine the rod position interval for this measurement based on the Gray code setting state of the current sampling; Step 4: Calculate the specific rod position for this measurement based on the A / D conversion result of the Gray code conditioning signal sampled this time; Step 5: Compare the calculated rod position result of this measurement with the previous valid calculated rod position result; Step 6: If the deviation between the calculated rod position result of the current measurement and the previous valid calculated rod position result is greater than +1, 0, -1 or -7, then the current measurement result is determined to be valid, and the rod position display is updated; Step 7: If the deviation between the calculated rod position result of the current measurement and the previous valid calculated rod position result is not greater than +1, 0, -1 or -7, then the current measurement result is determined to be invalid, and the previous valid calculated rod position result is used to replace the current rod position calculation result, and the rod position display is updated. Step 8: The measurement of the rod position is now complete; Step 9: Update the rod position measurement display.

2. The anti-interference method for full-stroke rod position measurement of a pressurized water reactor based on Gray code as described in claim 1, characterized in that: Step 1 further includes expanding the bar position interval corresponding to the Gray code tuning state, so that the overlap between the bar position intervals corresponding to two adjacent Gray code tuning states is increased.

3. The anti-interference method for full-stroke rod position measurement of a pressurized water reactor based on Gray code as described in claim 2, characterized in that: The overlap is at least 3 machine steps.

4. The anti-interference method for full-stroke rod position measurement of a pressurized water reactor based on Gray code as described in claim 2, characterized in that: In step 1, a certain multiple is 0.8 or higher.

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