A method for testing electromagnetic susceptibility of process system equipment used in nuclear power plants

Abstract

The present invention belongs to the instrumentation and control technology of nuclear power plants, and specifically relates to a method for testing electromagnetic sensitivity of process system equipment applied to nuclear power sites, wherein a test system is built, the equipment under test is determined, the test parameters are determined to obtain the measured antenna transmission power, and after the interference test, the operating parameters of the equipment under test are continuously observed and recorded to make an over-limit interference judgment. This method fills the gap in the electromagnetic compatibility test method of nuclear power plants, clarifies the control of the equipment under test and the range of observed signals, and achieves a wider range of equipment types within a limited number of tests, involving all important equipment types and signal types. The equipment under test can represent the electromagnetic sensitivity characteristics of the production process system, and has the characteristics of importance, sensitivity, diversity, etc.; the judgment of interference generation is made, starting from the actual situation of the nuclear power site, and meeting the authenticity and accuracy of the on-site equipment diagnosis.

Description

Technical Field

[0001] The invention belongs to the instrumentation and control technology of nuclear power plants, and in particular relates to an electromagnetic sensitivity testing method for process system equipment applied to nuclear power sites. Background Art

[0002] Looking at the relevant standards at home and abroad, such as the US RG1.180 "Guidelines for EMI / RFI Evaluation of Safety-Related I&C Systems", the French "Rules for the Design and Construction of Nuclear Island Electrical Equipment" (RCCE), the German KTA 3503 5.4 "Electromagnetic Compatibility EMC Test", and my country's "Nuclear Power Plant Design Safety Regulations" (HAF102) have respectively put forward the requirements for electromagnetic compatibility of equipment, and the Chinese standard GB / T 11684-2003 "Electromagnetic Environmental Conditions and Test Methods for Nuclear Instruments" stipulates the test method for the electromagnetic interference (EMI) of nuclear reactor instruments. However, all electromagnetic sensitivity tests are conducted in the laboratory test environment. Due to the complex conditions of the nuclear power site, the shielding and reflection of wireless signals coexist, which makes it possible for the electromagnetic power of the wireless signals on site to focus and act on the process system equipment; while the traditional standard test is conducted in the darkroom of the laboratory, there is no shielding and reflection environment, so the electromagnetic environment of the process system equipment is different from that of the laboratory environment, and the electromagnetic compatibility test data before the equipment leaves the factory cannot be directly reused.

[0003] At present, there is no standard to follow for electromagnetic susceptibility testing in field environments at home and abroad. Some nuclear power units have explored and practiced electromagnetic compatibility testing in field environments, but there are still deficiencies or disadvantages such as redundant steps, many irrelevant signals, long occupied time windows, lack of quantitative analysis and unclear test results. In order to overcome these deficiencies or disadvantages, the present invention combines the laboratory test method with the operating status of field equipment to study the electromagnetic susceptibility test method of nuclear power plant process system equipment in a real environment that can be operated on site. Summary of the invention

[0004] The purpose of the present invention is to provide a method for testing electromagnetic susceptibility of process system equipment applied to nuclear power sites, which can truly and accurately measure the electromagnetic susceptibility of process system equipment in nuclear power plants.

[0005] The technical solution of the present invention is as follows:

[0006] A method for testing electromagnetic susceptibility of process system equipment applied to a nuclear power site, the method comprising the following steps:

[0007] Step 1: Build a test system

[0008] The signal generator is connected to the power amplifier, and then to the horn antenna and the logarithmic antenna respectively, and the electric field strength is detected by using a field strength detector; the horn antenna and the logarithmic antenna face the device under test;

[0009] Step 2: Determine the device under test

[0010] Step 3: Determine test parameters

[0011] Including 3.1 determine the test frequency band and test frequency; 3.2 determine the antenna distance; 3.3 determine the measured antenna transmission power P r ;

[0012] Step 4: Conduct interference test

[0013] Use a field strength detector to check and record the radio field on site. If the detected radio field strength changes smoothly from low frequency to high frequency, proceed to the next step; otherwise, turn off the noise source equipment;

[0014] Keep the interference antenna at the same height as the center of the device under test;

[0015] The interference signal source ranges from low frequency band to high frequency band, and the interference signal is set according to the test frequency set in step 3.1;

[0016] The power amplifier amplifies the power of the interference signal to keep it at the measured antenna transmission power P determined in step 3.3. r

[0017] Use a field strength tester to test within the coverage area and keep the test status for 30 to 300 seconds; if the interference signal field strength reading appears, it means that the interference signal is continuously being transmitted, and the field strength tester should be retracted;

[0018] Step 5: Test result determination

[0019] Continuously observe and record the operating parameters of the equipment under test and make judgments based on the following situations:

[0020] 1) For the signal of the switching device, there are only two states. When the electromagnetic interference is applied, if the original signal state does not flip, it is considered that no over-limit interference has occurred; if the original signal state flips, it is considered that over-limit interference has occurred;

[0021] 2) For analog device signals, if the analog device signal jump amplitude exceeds 0.5% of the channel range, it is considered that there is an over-limit interference; otherwise, it is considered that there is no over-limit interference;

[0022] In the step 4),

[0023] While maintaining the test state, observe the output signal curve of the device under test or the panel display value for any jumps, and record the working state and received power of the device under test.

[0024] In the step 4), if the device under test always works normally under the interference of the current test frequency, it is considered that the interference threshold of the device under test at the frequency is not lower than the current receiving power.

[0025] In the step 4), if a jump is observed in the output signal curve or panel display value of the device under test while maintaining the test state, the receiving power is decreased by 3dB steps, and the test observation of the previous step is repeated until the observed signal is normal; next, the receiving power is increased by 1dB steps, and the test observation of the previous step is repeated until the observed signal reappears abnormal, and the power of the received signal at this time is reduced by 1dB to obtain the interference threshold under the current interference signal; the device working status and receiving power are recorded.

[0026] In step 3) described above, 3.1 determines the test frequency band and test frequency point, selects 18 test frequency bands, and sets 1 to 3 test frequency points for each frequency band, as shown in the following table

[0027]

[0028] In step 3) described above, 3.2 determines the antenna distance, which is 45-55 cm.

[0029] In the step 3), 3.3 determines the antenna transmission power, including determining the electric field strength at 50 cm away from the antenna to ensure that the power of the transmitting antenna can reach the theoretical transmission power.

[0030] The process of determining the theoretical transmission power in step 3) is as follows:

[0031] 1) Calculate the maximum equivalent isotropic radiated power EIRP m , unit W

[0032]

[0033] Among them, P m The maximum transmission power of the terminal specified by the state under this standard frequency;

[0034] 2) Calculate the maximum theoretical value of the electric field strength E at the location of the device under test m ;

[0035]

[0036] D-the distance to the wireless signal transmission source;

[0037] 3) Reverse calculation of the transmit power EIRP at the antenna side at 50cm 50

[0038]

[0039] 4) Calculate the equivalent transmission power P of the interference antenna eq ;

[0040] P eq =10×log(1000×EIRP 50 ).

[0041] In step 3) described above, 3.3 determines the antenna transmission power, and determines the measured antenna transmission power P r The process is as follows:

[0042] 1) Determine the test environment;

[0043] 2) The distance between the reference center point of the test antenna and the field strength probe is fixed at 50cm;

[0044] 3) Measure the transmission cable power loss CL;

[0045] 4) Adjust the antenna gain to G a ;

[0046] 5) Adjust the power amplifier gain to G p ;

[0047] 6) Adjust the signal source output power until the field strength probe receives a value close to the theoretical field strength value;

[0048] 7) Record the signal source output power P s ;

[0049] 8) Calculate the measured omnidirectional equivalent radiated power according to the following formula, that is, the measured antenna transmission power P r

[0050] P r =P s +G p -CL+G a .

[0051] In the step 1, the power amplifier can be a low-frequency power amplifier, a high-frequency power amplifier or a combination of the two; the signal generator has a range of 9KHz-6GHz and an accuracy of ±6300Hz; the low-frequency power amplifier has a range of 80MHz-1GHz and an accuracy of ±3.5dB; the high-frequency power amplifier has a range of 1GHz-6GHz and an accuracy of ±3.0dB; the horn antenna has a range of 1GHz-18GHz and an accuracy of ±1.5dB; the field strength detector has a range of 9KHz-6GHz and an accuracy of ±1.5dB; the logarithmic antenna has a range of 150MHz-1GHz and an accuracy of ±1.5dB.

[0052] The remarkable effects of the present invention are as follows:

[0053] This method fills the gap in the on-site electromagnetic compatibility test methods of nuclear power plants, specifically:

[0054] Through design step 1, an original electromagnetic susceptibility test method suitable for nuclear power site environment is proposed;

[0055] In step 2, the tested equipment and observed signal range control are clarified to achieve wider equipment type coverage within a limited number of tests, involving all important equipment types and signal types. The tested equipment can represent the electromagnetic sensitivity characteristics of the production process system and has the characteristics of importance, sensitivity, and diversity;

[0056] In step 3, innovations are made in interference signal selection and on-site restoration, using all modulation signals specified by the operator's standards and actual simulation of the real environment to verify the theoretical calculation parameters;

[0057] Steps 4-5 are used to determine the interference generation, based on the actual situation of the nuclear power site, to ensure the authenticity and accuracy of on-site equipment diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the test system; DETAILED DESCRIPTION

[0059] The present invention will be further described below through the accompanying drawings and specific implementation methods.

[0060] The electromagnetic susceptibility test method for process system equipment applied to nuclear power sites adopts the following steps;

[0061] Step 1: Build a test system

[0062] Build a test system such as Figure 1 shown.

[0063] The signal generator is connected to the power amplifier, and then to the horn antenna and the logarithmic antenna respectively, and the electric field strength is detected by using a field strength detector; the horn antenna and the logarithmic antenna face the device under test;

[0064] The power amplifier may be a low frequency power amplifier, a high frequency power amplifier, or a combination of the two;

[0065] The specific equipment specifications and models required for the test system depend on the on-site test content and test environment conditions. The recommended test system equipment list is shown in Table 1.

[0066] Table 1 Test system equipment list

[0067] Serial number name quantity Range Accuracy Remark 1 Signal Generator 1 unit 9KHz-6GHz ±6300Hz 2 Low frequency power amplifier 1 unit 80MHz-1GHz ±3.5dB 3 High frequency power amplifier 1 unit 1GHz-6GHz ±3.0dB 4 Logarithmic Antenna 1 pair 150MHz-1GHz ±1.5dB 5 Horn Antenna 1 pair 1GHz-18GHz ±1.5dB 6 Field strength detector 1 set 9KHz-6GHz ±1.5dB

[0068] Step 2: Identify the device under test

[0069] Since there are many types and quantities of sensors, instruments, and cabinets in nuclear power plants, the equipment under test should be representative. This method is based on the reactor type of nuclear power units and the characteristics of the equipment used. After demonstration by senior experts in various professions, according to the selection principles of importance, sensitivity, and diversity, under the premise of ensuring comprehensive testing of key signal type equipment, the installation status, physical principles, manufacturers, installation locations, concentration and other factors of the equipment under test are comprehensively considered. By replacing the same type of equipment, the number of tests is minimized to cover more types and quantities of equipment or signals. Finally, 47 sets of equipment were tested. The specific test equipment is as follows:

[0070] Table 2 List of tested equipment

[0071]

[0072] Step 3: Determine test parameters

[0073] 3.1 Determine the test frequency band and test frequency

[0074] Domestic mobile phones, tablet computers and other wireless terminals are used as target interference sources. In addition to weak signals such as NFC and Bluetooth that obviously do not cause electromagnetic interference, the RF signals that can be emitted by the terminals include public network standard signals and WiFi signals. Based on this, 18 test frequency bands are selected, and 1 to 3 test frequency points are set for each frequency band (a total of 42 frequency points), see Table 3.

[0075] Table 3 Test frequency band and frequency point table

[0076]

[0077] 3.2 Determine the antenna distance

[0078] For electromagnetic compatibility tests conducted under laboratory conditions, the test distance from the interference antenna to the device under test is generally 3 meters. However, the space in the nuclear power plant is small and the test site is limited. Even in electrical plants with better conditions, the maximum distance between the front and back rows of cabinets (devices under test) does not exceed 1.2 meters. Moreover, the interference antenna itself has a certain size, and on-site testing cannot be performed at the test distance in the laboratory.

[0079] Considering that the interference signal is a conical field, the longer the distance, the larger the effective area, and the more tested devices (signals) are covered. After on-site investigation and based on the actual conditions of the nuclear power plant, the test distance was finally determined to be 50±5cm, and the interference antenna was horizontally aligned with the sensitive parts of the tested device.

[0080] 3.3 Determine the antenna transmission power

[0081] First, calculate the theoretical transmission power. When the on-site wireless terminal is close to the device under test (such as scanning the QR code on the device sign, etc.), the distance is 10cm. Therefore, the transmission power of the test system interference antenna should be equivalent to the electric field strength generated when the wireless terminal is at the maximum transmission power (the receiving power of the device under test) at 10cm. According to Appendix A.1 of GB / T 12572-2008, calculate the theoretical transmission power of each standard / frequency at 50cm.

[0082] The calculation steps of theoretical transmission power are as follows:

[0083] 5) Calculate the maximum equivalent isotropic radiated power EIRP m , unit W

[0084]

[0085] Among them, P m It is the maximum transmit power of the terminal specified by the country at this standard frequency, in dBm.

[0086] 6) Calculate the maximum theoretical value of the electric field strength E at the location of the device under test m ; Unit: V / m

[0087]

[0088] D-the distance to the wireless signal transmission source, in meters, the same below.

[0089] 7) Reverse calculate the transmit power EIRP at the antenna side at 50cm 50

[0090]

[0091] 8) Calculate the equivalent transmission power P of the interference antenna eq , unit: dBm.

[0092] P eq =10×log(1000×EIRP 50 )

[0093] Then build the environment to conduct actual measurements to verify the transmission power.

[0094] according to Figure 1 Build a test system, use a field strength tester to read the electric field strength at a distance of 50 cm from the antenna, and compare it with the theoretically calculated electric field strength to ensure that the transmission power of the transmission system reaches the required transmission level.

[0095] The actual measurement and verification steps are as follows:

[0096] 1) Select a site with good electromagnetic environment and no other electromagnetic interference as the test environment;

[0097] 2) The distance between the reference center point of the test antenna and the field strength probe is fixed at 50cm;

[0098] 3) Measure the transmission cable power loss CL in dB;

[0099] 4) Adjust the antenna gain to G a , unit: dBi;

[0100] 5) Adjust the power amplifier gain to G p , unit: dB;

[0101] 6) Adjust the signal source output power until the field strength probe receives a value close to the theoretical field strength value;

[0102] 7) Record the signal source output power P s , unit: dB;

[0103] 8) Calculate the measured omnidirectional equivalent radiated power according to the following formula, that is, the measured antenna transmission power P r .

[0104] P r =P s +G p -CL+G a

[0105] Step 4: Test Execution

[0106] According to the established test plan, conduct interference tests on the on-site process equipment selected in step 2 one by one. During the test, record the electric field strength of each standard and frequency point on the equipment surface, and record the operating status of the equipment and the value of the observed signal for judgment and analysis. The test execution steps are briefly described as follows:

[0107] 1) The test equipment and the equipment under test should be in normal working condition; use a field strength detector to check and record the radio field on site. If the detected radio field strength changes smoothly from low frequency to high frequency (bottom noise), proceed to the next step. If the intensity of the radio field is detected to be significantly increased, it is necessary to check whether there are any wireless devices working in the frequency band nearby, and temporarily turn off the noise source equipment to avoid interference with the test.

[0108] 2) The interference antenna and the center of the device under test should be kept at the same height; the interference antenna and the device under test should be kept at 50±5cm;

[0109] 3) The interference signal source moves from low frequency band to high frequency band, and the interference signal is set according to step 3.1 to set the frequency of the interference signal source;

[0110] 4) Use the signal generator to transmit the interference signal. After the power amplifier amplifies the power of the interference signal, the signal power is maintained at the transmission power level P determined in step 3.3. r ;

[0111] 5) Use a field strength tester to test within the coverage area. If the interference signal field strength reading appears, it means that the interference signal is continuously being transmitted. Retract the field strength tester; maintain the test state for 30 seconds to 300 seconds;

[0112] 6) During the test state maintenance process, observe whether the output signal curve of the device under test or the panel display value (observation signal) has any jump, and record the working status and received power of the device under test;

[0113] 7) If the device under test always works normally under the interference of the current test frequency, it is considered that the interference threshold of the device under test at the frequency is not lower than the current receiving power; because there is no situation in reality where the receiving power of the device under test is higher than the current receiving power at the current frequency, the operation of looking for a higher threshold is not performed; record the working status and receiving power of the device;

[0114] 8) If the output signal curve or panel display value of the device under test is observed to jump during the test state, the receiving power is decreased by 3dB step, and the test observation of the previous step is repeated until the observed signal is normal; then the receiving power is increased by 1dB step, and the test observation of the previous step is repeated until the observed signal reappears abnormal. The power of the received signal is reduced by 1dB at this time to obtain the interference threshold (critical interference power) under the current interference signal; record the working status of the equipment and the receiving power.

[0115] Step 5: Test result determination

[0116] During the test, the operating parameters of the equipment are continuously observed and recorded in the main control room or on-site control station. If the following conditions exist, it can be determined that interference exists:

[0117] 1) For the signal of the switching device, there are only two states. When the electromagnetic interference is applied, if the original signal state does not flip, it is considered that no over-limit interference has occurred; if the original signal state flips, it is considered that over-limit interference has occurred;

[0118] 2) For analog device signals, according to the technical specifications of process equipment procurement, the general allowable error of thermal instruments is 0.5%. The instrument range is not less than the channel range. From a conservative perspective, 0.5% of the channel range is set as the analog interference over-limit judgment criterion, that is, if the analog device signal jump amplitude exceeds 0.5% of the channel range, it is considered that there is over-limit interference; otherwise, it is considered that no over-limit interference has occurred.

[0119] For other equipment signals, the requirements for judging whether there is no interference exceeding the limit during the test are: there is no abnormal alarm information in the running equipment, and there is no jump or jitter in the numerical monitoring of the observed signal.

Claims

1. A method for testing electromagnetic susceptibility of process system equipment applied to nuclear power sites, characterized in that: The method comprises the following steps: Step 1: Build a test system The signal generator is connected to the power amplifier, and then to the horn antenna and the logarithmic antenna respectively, and the electric field strength is detected by using a field strength detector; the horn antenna and the logarithmic antenna face the device under test; Step 2: Determine the device under test Step 3: Determine test parameters include 3.1 Determine the test frequency band and test frequency point; 3.2 Determine the antenna distance; 3.3 Determine the measured antenna transmission power P r ; Step 4: Conduct interference test Use a field strength detector to check and record the radio field on site. If the detected radio field strength changes smoothly from low frequency to high frequency, proceed to the next step; Otherwise, turn off the noise source equipment; Keep the interference antenna at the same height as the center of the device under test; The interference signal source ranges from low frequency band to high frequency band, and the interference signal is set according to the test frequency set in step 3.1; The power amplifier amplifies the power of the interference signal to keep it at the measured antenna transmission power P determined in step 3.

3. r Use a field strength tester to test within the coverage area and keep the test status for 30 to 300 seconds; if the interference signal field strength reading appears, it means that the interference signal is continuously being transmitted, and the field strength tester should be retracted; Step 5: Test result determination Continuously observe and record the operating parameters of the equipment under test and make judgments based on the following situations: 1) For the signal of the switching device, there are only two states. When the electromagnetic interference is applied, if the original signal state does not flip, it is considered that no over-limit interference is generated; If the original signal state is reversed, it is considered that there is an over-limit interference; 2) For analog device signals, if the analog device signal jump amplitude exceeds 0.5% of the channel range, it is considered that there is out-of-limit interference; otherwise, it is considered that no out-of-limit interference occurs.

2. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 4), While maintaining the test state, observe the output signal curve of the device under test or the panel display value for any jumps, and record the working state and received power of the device under test.

3. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 4), if the device under test always works normally under the interference of the current test frequency, it is considered that the interference threshold of the device under test at the frequency is not lower than the current receiving power.

4. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 4), if a jump is observed in the output signal curve or panel display value of the device under test while maintaining the test state, the receiving power is decreased by 3dB steps, and the test observation of the previous step is repeated until the observed signal is normal; next, the receiving power is increased by 1dB steps, and the test observation of the previous step is repeated until the observed signal reappears abnormal, and the power of the received signal at this time is reduced by 1dB to obtain the interference threshold under the current interference signal; the device working status and receiving power are recorded.

5. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 3), 3.1 determines the test frequency band and test frequency points, selects 18 test frequency bands, and sets 1 to 3 test frequency points for each frequency band, specifically: For GSM 900 frequency band, DCS 1800 frequency band, CDMA2000 824-835 frequency band, TD-SCDMA 1880-1900 frequency band, TD-SCDMA 2010-2125 frequency band, WCDMA 1920-1940 frequency band, TDD 2575-2635 frequency band, FDD 1920-1965 frequency band, FDD 1710-1780 frequency band, WLAN 5725-5850 frequency band, set 3 frequency points for each frequency band; For WCDMA 909-915 frequency band, TDD 2010-2025 frequency band, FDD 824-835 frequency band, FDD 8800-915 frequency band, set one frequency point for each frequency band; For the TDD standard 1880-1920, TDD standard 2300-2370 frequency band, WLAN standard 2400-2483.5 frequency band, WLAN standard 5150-5350 frequency band, two frequency points are set for each frequency band.

6. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In step 3) described above, 3.2 determines the antenna distance, which is 45-55 cm.

7. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 3), 3.3 determines the antenna transmission power, including determining the electric field strength at 50 cm away from the antenna to ensure that the power of the transmitting antenna can reach the theoretical transmission power.

8. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 7, characterized in that: The process of determining the theoretical transmission power in step 3) is as follows: 1) Calculate the maximum equivalent isotropic radiated power EIRP m , unit W Among them, P m It is the maximum transmission power of the terminal specified by the state under the standard frequency; 2) Calculate the maximum theoretical value of the electric field strength E at the location of the device under test m ; D-the distance to the wireless signal transmission source; 3) Reverse calculation of the transmit power EIRP at the antenna side at 50cm 50 4) Calculate the equivalent transmission power P of the interference antenna eq ; P eq =10×log(1000×E.I.R.P 50 )。 9. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In step 3) described above, 3.3 determines the antenna transmission power, and determines the measured antenna transmission power P r The process is as follows: 1) Determine the test environment; 2) The distance between the reference center point of the test antenna and the field strength probe is fixed at 50cm; 3) Measure the transmission cable power loss CL; 4) Adjust the antenna gain to G a ; 5) Adjust the power amplifier gain to G p ; 6) Adjust the signal source output power until the field strength probe receives a value close to the theoretical field strength value; 7) Record the signal source output power P s ; 8) Calculate the measured omnidirectional equivalent radiated power according to the following formula, that is, the measured antenna transmission power P r P r =P s +G p -CL+G a 。 10. The electromagnetic susceptibility testing method for process system equipment applied to a nuclear power site according to claim 1, characterized in that: In the step 1, the power amplifier is a low-frequency power amplifier, a high-frequency power amplifier or a combination of the two; the signal generator has a range of 9KHz-6GHz and an accuracy of ±6300Hz; the low-frequency power amplifier has a range of 80MHz-1GHz and an accuracy of ±3.5dB; the high-frequency power amplifier has a range of 1GHz-6GHz and an accuracy of ±3.0dB; the horn antenna has a range of 1GHz-18GHz and an accuracy of ±1.5dB; the field strength detector has a range of 9KHz-6GHz and an accuracy of ±1.5dB; the logarithmic antenna has a range of 150MHz-1GHz and an accuracy of ±1.5dB.

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