A method and device for automatically measuring the impedance frequency characteristics of a DC transmission line

Abstract

The present invention provides a method and device for automatically measuring the impedance frequency characteristics of a DC transmission line. The device includes an input device, a data processor, a variable frequency power supply, a control output device, a result display device, an A / D conversion unit, a sensor, and a measurement input module. The data processor communicates with the variable frequency power supply through an RS232 serial port; the variable frequency power supply output signal is output to the DC transmission line under test through the control output device; the DC transmission line under test is connected to the measurement input module; the measurement input module is connected to the sensor; the sensor is connected to the A / D conversion unit; the A / D conversion unit is connected to the data processor; the data processor is connected to the result display device to display the test results. The method and device use a DSP chip to control the output of the variable frequency power supply, calculate the resonant frequency section of the line through the input line length, automatically skip the resonant frequency section, and ensure the accuracy of the line impedance frequency characteristic measurement.

Description

Technical Field

[0001] The invention relates to the measurement of parameter characteristics of a DC transmission line in an electric power system, and in particular to a method and a device for automatically measuring impedance frequency characteristics of a DC transmission line. Background Art

[0002] The length of ultra-high and extra-high voltage direct current transmission lines is generally more than 1000km, and the transmission speed of the line is generally close to the speed of light (c = 300000km / s). When the length is greater than 1500km, the capacitance and inductance characteristics of the line input impedance change. When the high voltage direct current transmission line is tested for frequency characteristics, the increase in test frequency will produce resonance points in different frequency segments, affecting the accuracy of the test results and even causing damage to the power supply. The traditional line impedance frequency characteristic test is carried out by the operator manually adjusting the power supply output frequency. The test efficiency is low and it is easy to collect frequency points in the resonant frequency segment. Summary of the invention

[0003] The purpose of the present invention is to provide a method and device for automatically measuring the impedance frequency characteristics of a DC transmission line, which calculates the resonant frequency section of the line by inputting the line length, automatically skips the resonant frequency section, and ensures the accuracy of the line impedance frequency characteristic measurement.

[0004] The technical solution of the present invention:

[0005] An automatic measurement device for impedance frequency characteristics of a DC transmission line comprises a setting input device, a data processor, a variable frequency power supply, a control output device, a result display device, an A / D conversion unit, a sensor and a measurement input module.

[0006] The setting input device is connected to the data processor and is used to input basic parameters required for each circuit into the data processor;

[0007] The data processor communicates with the variable frequency power supply through the RS232 serial port; the variable frequency power supply output signal is output to the DC transmission line under test through the control output device;

[0008] The DC transmission line under test is connected to the measurement input module, and the automatic measurement device collects data through the measurement input module;

[0009] The measurement input module is connected to the sensor to collect the frequency, voltage and current signals of the DC transmission line under test;

[0010] The sensor is connected to an A / D conversion unit to perform digital-to-analog conversion of an input signal;

[0011] The A / D conversion unit is connected to the data processor to process the collected measurement data and perform calculations;

[0012] The data processor is connected to the result display device to display the test result.

[0013] The setting input device is a mouse and a keyboard.

[0014] The data processor is a DSP chip of model TMS320F2812.

[0015] The model of the variable frequency power supply is Chroma6530, the output power is 3000VA, and the output frequency range is 20Hz to 2500Hz.

[0016] The control output device is a relay switching device for switching between different measurement modes.

[0017] The result display device is a liquid crystal screen with a resolution of 320×240.

[0018] The sensor comprises a voltage sensor and a current sensor. The voltage sensor has a measuring range of 1000V and an accuracy of ±1%, and the current sensor has a measuring range of 5A and an accuracy of ±1%.

[0019] A method for automatically measuring the impedance frequency characteristics of a DC transmission line comprises the following specific steps:

[0020] S1. The control output device and the measurement input module of the automatic measurement device for impedance frequency characteristics of a DC transmission line as described above are respectively connected to the DC transmission line under test, and before starting the test, the grounding switch at the head end of the line is grounded;

[0021] S2. Set the length of the input line of the input device, set the starting frequency point of the test, open the grounding switch at the head end of the line, and start the test;

[0022] S3. The automatic measuring device calculates a reasonable test frequency segment, and performs automatic testing and data collection according to the calculated frequency points;

[0023] S4. After the test is completed, the device displays the test results;

[0024] S5. Record the results and ground the grounding switch at the beginning of the line.

[0025] The reasonable test frequency segment calculated in step S3 is specifically:

[0026] Resonance frequency interval of DC transmission line Where V 光速 =300×10 3km / s, l is the line length, unit is km; the resonant frequency point of the line is n×Δf, where n is an integer and n>0; because the output frequency range of the variable frequency power supply is 20Hz~2500Hz, the resonant frequency point of the line only considers the frequency points within 20Hz~2500Hz; the frequency point between the two resonant frequencies is the ideal test frequency point, the ideal test frequency point Where n is an integer and n>0; the frequency step output by the automatic measuring device is 2Hz, and the reasonable impedance frequency characteristic test section is Δf1±n1×2Hz, where n1 is 0, 1, 2, i.e. Δf1 and the two step frequency points before and after Δf1.

[0027] The beneficial effects of the present invention are as follows: a DSP chip is used to control the output of a variable frequency power supply, the resonant frequency section of the line is calculated by inputting the line length, the resonant frequency section is automatically skipped, and the accuracy of the line impedance frequency characteristic measurement is ensured. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the device test wiring structure of the present invention.

[0029] Figure 2 This is the two-phase positive sequence resistance-frequency characteristic curve of the present invention.

[0030] Figure 3 This is the two-phase positive sequence inductance-frequency relationship characteristic curve of the present invention.

[0031] Figure 4 It is the two-phase zero-sequence resistance-frequency characteristic curve of the present invention.

[0032] Figure 5 It is the two-phase zero-sequence inductance-frequency characteristic curve of the present invention. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] An automatic measurement device for impedance frequency characteristics of a DC transmission line comprises an input device 1, a data processor 2, a variable frequency power supply 3, a control output device 4, a result display device 5, an A / D conversion unit 6, a sensor 7 and a measurement input module 8.

[0035] The setting input device 1 is connected to the data processor 2 and is used to input basic parameters required for each circuit into the data processor 2;

[0036] The data processor 2 communicates with the variable frequency power supply 3 via the RS232 serial port; the output signal of the variable frequency power supply 3 is output to the DC transmission line under test via the control output device 4;

[0037] The DC transmission line under test is connected to the measurement input module 8, and the automatic measurement device collects data through the measurement input module 8;

[0038] The measurement input module 8 is connected to the sensor 7 to collect the frequency, voltage and current signals of the DC transmission line under test;

[0039] The sensor 7 is connected to the A / D conversion unit 6 to perform digital-to-analog conversion of the input signal;

[0040] The A / D conversion unit 6 is connected to the data processor 2 to process the collected measurement data and perform calculations;

[0041] The data processor 2 is connected to the result display device 5 to display the test result.

[0042] The setting input device 1 is a mouse and a keyboard.

[0043] The data processor 2 is a DSP chip of model TMS320F2812.

[0044] The model of the variable frequency power supply 3 is Chroma6530, the output power is 3000VA, and the output frequency range is 20Hz-2500Hz.

[0045] The control output device 4 is a relay switching device for switching between different measurement modes.

[0046] The result display device 5 is a liquid crystal screen with a resolution of 320×240.

[0047] The sensor 7 includes a voltage sensor and a current sensor. The voltage sensor has a measuring range of 1000V and an accuracy of ±1%, and the current sensor has a measuring range of 5A and an accuracy of ±1%.

[0048] A method for automatically measuring the impedance frequency characteristics of a DC transmission line comprises the following specific steps:

[0049] S1. The control output device 4 and the measurement input module 8 of the automatic measurement device for the impedance frequency characteristics of a DC transmission line as described above are respectively connected to the DC transmission line under test. Before starting the test, the grounding switch at the head end of the line is grounded;

[0050] S2. By setting the length of the input line of the input device 1, setting the starting frequency point of the test, opening the grounding switch at the first end of the line, and starting the test;

[0051] S3. The automatic measuring device calculates a reasonable test frequency segment, and performs automatic testing and data collection according to the calculated frequency points;

[0052] S4. After the test is completed, the device displays the test results;

[0053] S5. Record the results and ground the grounding switch at the beginning of the line.

[0054] The reasonable test frequency segment calculated in step S3 is specifically:

[0055] Resonance frequency interval of DC transmission line Where V 光速 =300×10 3 km / s, l is the line length, unit is km; the resonant frequency point of the line is n×Δf, where n is an integer and n>0; because the output frequency range of the variable frequency power supply 3 is 20Hz~2500Hz, the resonant frequency point of the line only considers the frequency points within 20Hz~2500Hz; the frequency point between the two resonant frequencies is the ideal test frequency point, the ideal test frequency point Where n is an integer and n>0; the frequency step output by the automatic measuring device is 2Hz, and the reasonable impedance frequency characteristic test section is Δf1±n1×2Hz, where n1 is 0, 1, 2, i.e. Δf1 and the two step frequency points before and after Δf1.

[0056] For example, the length of the DC line under test is l = 1900 km

[0057] Calculate the line resonant frequency interval

[0058] The resonant frequency of the line will appear at n×Δf, that is, n×40Hz (n is an integer and n>0);

[0059] The ideal test frequency for this line impedance frequency test (n is an integer and n>0);

[0060] The step value of the frequency output of the variable frequency power supply is 2Hz, and the device data processor 2 calculates the frequency range as (n is an integer and n>0, n1=0, 1, 2).

[0061] Set the starting test frequency of the device to 20Hz. The device will output according to the frequency points in Table 1 and automatically complete the test.

[0062] 20 216 416 616 816 1016 1216 1416 1616 1816 2016 2216 2416 22 218 418 618 818 1018 1218 1418 1618 1818 2018 2218 2418 24 220 420 620 820 1020 1220 1420 1620 1820 2020 2220 2420 222 422 622 822 1022 1222 1422 1622 1822 2022 2222 2422 224 424 624 824 1024 1224 1424 1624 1824 2024 2224 2424 56 256 456 656 856 1056 1256 1456 1656 1856 2056 2256 2456 58 258 458 658 858 1058 1258 1458 1658 1858 2058 2258 2458 60 260 460 660 860 1060 1260 1460 1660 1860 2060 2260 2460 62 262 462 662 862 1062 1262 1462 1662 1862 2062 2262 2462 64 264 464 664 864 1064 1264 1464 1664 1864 2064 2264 2464 96 296 496 696 896 1096 1296 1496 1696 1896 2096 2296 2496 98 298 498 698 898 1098 1298 1498 1698 1898 2098 2298 2498 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 102 302 502 702 902 1102 1302 1502 1702 1902 2102 2302 104 304 504 704 904 1104 1304 1504 1704 1904 2104 2304 136 336 536 736 936 1136 1336 1536 1736 1936 2136 2336 138 338 538 738 938 1138 1338 1538 1738 1938 2138 2338 140 340 540 740 940 1140 1340 1540 1740 1940 2140 2340 142 342 542 742 942 1142 1342 1542 1742 1942 2142 2342 144 344 544 744 944 1144 1344 1544 1744 1944 2144 2344 176 376 576 776 976 1176 1376 1576 1776 1976 2176 2376 178 378 578 778 978 1178 1378 1578 1778 1978 2178 2378 180 380 580 780 980 1180 1380 1580 1780 1980 2180 2380 182 382 582 782 982 1182 1382 1582 1782 1982 2182 2382 184 384 584 784 984 1184 1384 1584 1784 1984 2184 2384

[0063] Table 1. Output frequency of 1900km line impedance frequency test device (unit: Hz)

[0064] Using the patented method and device of this invention, measurements were completed on the ±1100kV Changji-Guquan UHV DC line of State Grid Corporation of China, and good results were achieved. The specific data are as follows.

[0065] 1. Impedance frequency characteristic parameters

[0066] 1.1 Two-phase positive sequence parameters

[0067] Table 2 Positive sequence parameter measurement results

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] The frequency characteristic curve after fitting the two-phase positive sequence frequency characteristic calculation results is as follows: Figure 2 Two-phase positive sequence resistance-frequency characteristic curve and Figure 3 The two-phase positive sequence inductance-frequency relationship characteristic curve is shown as follows:

[0074] 1.2 Two-phase zero-sequence parameters

[0075] Table 3 Zero sequence parameter measurement results

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] The frequency characteristic curve after fitting the two-phase zero-sequence frequency characteristic calculation results is as follows Figure 4 Two-phase zero-sequence resistance-frequency characteristic curve and Figure 5 Two-phase zero-sequence inductance-frequency characteristic curve.

[0082] From the above Tables 2 and 3 and Figure 2-Figure 5 As shown, the automatic measurement method of the present invention automatically skips the resonant frequency section, thereby ensuring the accuracy of the line impedance frequency characteristic measurement.

[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for automatically measuring the impedance frequency characteristics of a DC transmission line, using an automatic measuring device for the impedance frequency characteristics of a DC transmission line, the device comprising a setting input device (1), a data processor (2), a variable frequency power supply (3), a control output device (4), a result display device (5), an A / D conversion unit (6), a sensor (7) and a measurement input module (8), The setting input device (1) is connected to the data processor (2) and is used to input basic parameters required for various circuits into the data processor (2); The data processor (2) communicates with the variable frequency power supply (3) via an RS232 serial port; the output signal of the variable frequency power supply (3) is output to the DC power transmission line under test via a control output device (4); The DC power transmission line to be measured is connected to the measurement input module (8), and the automatic measurement device collects data through the measurement input module (8); The measurement input module (8) is connected to the sensor (7) to collect frequency, voltage and current signals of the DC power transmission line under test; The sensor (7) is connected to the A / D conversion unit (6) to perform digital-to-analog conversion of the input signal; The A / D conversion unit (6) is connected to the data processor (2) to process the collected measurement data and perform calculations; The data processor (2) is connected to a result display device (5) to display the test results, characterized in that: The method comprises the following specific steps: S1. The control output device (4) and the measurement input module (8) of the DC transmission line impedance frequency characteristic automatic measurement device are respectively connected to the DC transmission line under test. Before starting the test, the grounding switch at the head end of the line is grounded; S2. By setting the input device (1) to input the length of the line, set the starting frequency point of the test, open the grounding switch at the first end of the line, and start the test; S3. The automatic measuring device calculates a reasonable test frequency segment, and performs automatic testing and data collection according to the calculated frequency points; S4. After the test is completed, the device displays the test results; S5. Record the results and ground the grounding switch at the head end of the line; The reasonable test frequency segment calculated in step S3 is specifically: Resonance frequency interval of DC transmission line Where V 光速 =300×10 3 km / s, l is the line length, unit is km; The resonant frequency point of the circuit is n×Δf, where n is an integer and n>0; because the output frequency range of the variable frequency power supply (3) is 20Hz~2500Hz, the resonant frequency point of the circuit only considers the frequency point within 20Hz~2500Hz; the frequency point between the two resonant frequencies is the ideal test frequency point, and the ideal test frequency point Where n is an integer and n>0; the frequency step output by the automatic measuring device is 2Hz, and the reasonable impedance frequency characteristic test section is Δf1±n1×2Hz, where n1 is 0, 1, 2, i.e. Δf1 and the two step frequency points before and after Δf1.

2. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The setting input device (1) is a mouse and a keyboard.

3. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The data processor (2) is a DSP chip of model TMS320F2812.

4. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The model of the variable frequency power supply (3) is Chroma6530, the output power is 3000VA, and the output frequency range is 20Hz-2500Hz.

5. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The control output device (4) is a relay switching device used for switching between different measurement modes.

6. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The result display device (5) is a liquid crystal screen with a resolution of 320×240.

7. The method for automatically measuring the impedance frequency characteristics of a DC transmission line according to claim 1, characterized in that: The sensor (7) comprises a voltage sensor and a current sensor. The voltage sensor has a measuring range of 1000V and an accuracy of ±1%, and the current sensor has a measuring range of 5A and an accuracy of ±1%.

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