A power distribution terminal synchronous acquisition performance test system and method

Abstract

The application provides a power distribution terminal synchronous acquisition performance test system, which comprises a GPS / Beidou signal transfer module, a synchronous test system and the like. The GPS / Beidou signal transfer module is used for realizing indoor GPS / Beidou signal coverage, so that each to-be-tested power distribution terminal device is time-synchronized through the GPS / Beidou signal in a test environment. The synchronous test system is used for outputting specified multi-channel electrical quantities, including voltage signals and current signals, to the to-be-tested power distribution terminal at an integral second moment. During the test, the synchronous test system ensures that the voltage signals and the current signals received by all the power distribution terminals participating in the test are completely consistent in time and amplitude. The to-be-tested power distribution terminal records the multi-channel electrical quantities and transmits the recorded waveforms to a test master station of the test system. The test master station analyzes the waveforms to determine whether the synchronous acquisition performance of each to-be-tested power distribution terminal meets the requirements. The system and the method are beneficial to the supervision of the synchronous acquisition performance of the power distribution terminal and ensure the reliability of the related advanced functions of the power distribution terminal based on synchronous acquisition.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution equipment detection, and particularly relates to a power distribution terminal synchronous acquisition performance test system and method. BACKGROUND

[0002] At present, the application of synchronous acquisition technology in the main network field is mature, and on this basis, advanced technologies such as traveling wave distance measurement and differential protection have been widely applied. The main network equipment mainly uses IEC 61850 protocol for communication, and when detecting, the communication message of the IEC 61850 protocol can be directly parsed to obtain the sampling time of the equipment, so as to judge the synchronous acquisition performance of the equipment. At present, the technical concept of synchronous acquisition has gradually been introduced from the main network field to the distribution network field, but the overall application is still in the exploratory stage. In particular, since the power distribution terminal mainly uses IEC 101 protocol and IEC 104 protocol for communication, the related messages do not contain the sampling time of the equipment and other related information, and the synchronous acquisition performance of the power distribution terminal cannot be evaluated by parsing the message, which leads to the fact that there is no mature power distribution terminal synchronous acquisition performance detection method at present, and the power distribution terminal cannot be controlled in the network detection link. The above problems need to be solved. SUMMARY

[0003] The present application provides a power distribution terminal synchronous acquisition performance test system and method, which is beneficial to controlling the synchronous acquisition performance of the power distribution terminal and ensuring the reliability of the related advanced functions of the power distribution terminal based on synchronous acquisition.

[0004] The present application adopts the following technical solutions.

[0005] A power distribution terminal synchronous acquisition performance test system is used for testing a power distribution terminal with GPS / Beidou time synchronization function, and comprises:

[0006] A GPS / Beidou signal forwarding module is used for realizing indoor GPS / Beidou signal coverage, so that each to-be-tested power distribution terminal device is time-synchronized through the GPS / Beidou signal in the test environment;

[0007] A synchronous test system is used for outputting specified multi-channel electrical quantities to the to-be-tested power distribution terminal at whole-second moments, and the electrical quantities include voltage signals and current signals;

[0008] During the test, the synchronous test system tests each to-be-tested power distribution terminal one by one, or tests multiple power distribution terminals at the same time. If multiple power distribution terminals are tested at the same time, each voltage channel is connected to the power distribution terminal in parallel, and each current channel is connected to the power distribution terminal in series, so as to ensure that the voltage signals and current signals received by all the power distribution terminals participating in the test are completely consistent in time and amplitude.

[0009] The power distribution terminal to be tested records the multi-channel electrical quantity, and transmits the recorded waveform to the test master station of the test system;

[0010] The test master station receives the waveform uploaded by all the power distribution terminals to be tested, and analyzes the waveform to determine whether the synchronous acquisition performance of each power distribution terminal to be tested meets the requirements.

[0011] The GPS / Beidou signal forwarding module comprises an outdoor signal receiver, a wire, and an indoor signal amplifier.

[0012] When the test system is in operation, the outdoor signal receiver is placed in an outdoor open area to receive GPS / Beidou signals; the wire is used to transmit the GPS / Beidou signals received by the outdoor signal receiver to the indoor signal amplifier; and the indoor signal amplifier amplifies the received GPS / Beidou signals to cover the entire indoor experimental environment, thereby ensuring that the test equipment with GPS / Beidou time synchronization function can be time-synchronized through GPS / Beidou signals in the indoor experimental environment.

[0013] The synchronous test system comprises a synchronous tester prepared by modifying a relay protection tester, and the functions of the synchronous tester include the functions of the relay protection tester before modification, and further include an output interface capable of ensuring that all output signals are output at an integral second.

[0014] When the power distribution terminal to be tested receives the multi-channel electrical quantity signals output by the synchronous test system, if the electrical quantity signals meet the recording wave starting condition, the recording wave function of the power distribution terminal is triggered, so that the power distribution terminal records the waveform within at least 80 ms before the recording wave trigger time and within at least 160 ms after the recording wave trigger time, and generates a recording wave file, which is sent to the test master station in the form of a waveform file.

[0015] After the test master station receives the waveform file uploaded by all the power distribution terminals to be tested, the recording wave file is analyzed.

[0016] The analysis method is as follows: according to the setting that the synchronous test system starts output at an integral second and the waveform of each cycle is 20 ms, the theoretical phase of a plurality of recording wave sampling time points is calculated, and the actual phase recorded by the recording wave file at the time point is compared, so as to calculate the synchronous acquisition error of the power distribution terminal, and determine whether the synchronous acquisition performance of the power distribution terminal meets the requirements.

[0017] The use method of the power distribution terminal synchronous acquisition performance test system is a power distribution terminal synchronous acquisition performance detection method, which comprises the following steps.

[0018] Step S1, experimental environment construction, including: experimental environment GPS / Beidou signal coverage, connecting the synchronous test system, the power distribution terminal to be tested, the test master station, and setting the recording wave trigger condition of the power distribution terminal to be tested.

[0019] Step S2, synchronous acquisition test, comprising: synchronously testing system output test waveform, the tested power distribution terminal triggers the recording condition and records the test waveform, and the tested power distribution terminal uploads the recorded waveform to the test master station;

[0020] Step S3, detection result analysis, comprising: waveform analysis, result analysis.

[0021] Step S1 comprises the following steps:

[0022] Step S1-1, GPS / Beidou signal coverage of experimental environment: the outdoor signal receiver of the GPS / Beidou signal transponder is placed in an outdoor open area, and a wire is used to connect it with the indoor signal amplifier of the GPS / Beidou signal transponder;

[0023] Step S1-2, connecting the synchronous test system, the tested power distribution terminal and the test master station: connecting the synchronous tester and the power distribution terminal participating in the detection in the mode of parallel voltage channels and series current channels; connecting the power distribution terminal and the test master station by using a network cable and an Ethernet switch to ensure normal communication between the power distribution terminal and the test master station;

[0024] Step S1-3, setting the recording trigger condition of the tested power distribution terminal: setting the recording start condition of each power distribution terminal participating in the detection to ensure that the power distribution terminal can normally record when the synchronous test system starts to output electrical quantity signals, and the power distribution terminal does not start recording when the synchronous test system does not output signals; if the synchronous tester detects multiple power distribution terminals at the same time, the recording start conditions of all power distribution terminals need to be kept consistent.

[0025] Step S2 comprises the following steps:

[0026] Step S2-1, synchronous test system output test waveform: first setting the test waveform that needs to be output by the synchronous test system, and then issuing a "start output" instruction, after receiving the instruction, the synchronous test system will start outputting at the next whole second;

[0027] Step S2-2, the tested power distribution terminal triggers the recording condition and records the test waveform: after receiving the signal output by the synchronous test system, the recording start condition is triggered, the terminal starts recording, and records the waveform at least 80 ms before the recording trigger time and at least 160 ms after the recording trigger time, and generates a recording file;

[0028] Step S2-3, the tested power distribution terminal uploads the recorded waveform to the test master station: the tested power distribution terminal sends the recorded recording file to the test master station through IEC 101 protocol or IEC 104 protocol.

[0029] Step S3 comprises the following steps:

[0030] Step S3-1, Waveform Analysis: The test master station analyzes the waveform recording file to obtain the waveform of each voltage and current signal, including the amplitude and sampling time of each sampling point;

[0031] Step S3-2, Result Analysis: The test master station compares the phase of the actual sampling time point of the recorded waveform with the theoretical phase of the corresponding time point to draw test conclusions;

[0032] The theoretical phase value of the actual sampling time point of the recorded waveform is calculated according to the output of the synchronous tester at the whole second, with each waveform cycle being 20ms long.

[0033] Specifically, the peak and trough points of the waveform are selected as performance evaluation points for synchronous data acquisition at the distribution terminal. The actual sampling time at each peak and trough point is calculated and compared with the theoretical value of the sampling time. For example, Figure 3 As shown, first select two adjacent zero-crossing points x 01 and x 02 Calculate the zero-crossing time. Assuming that actual sampling may not occur at the zero-crossing point, select the nearest sampling point x before or after the zero-crossing point. (n-1) x (n) and x (m-1) x (m) The actual sampling times corresponding to these sampling points are T. (n-1) T (n) and T (m-1) T (m) The zero-crossing time T of the waveform is approximately calculated using linear interpolation. 01 and T 02 T 01 The calculation formula for T is shown in formula (1) below. 02 The calculation formula and T 01 The calculation formula is similar;

[0034] The actual sampling time T between the peak and valley points between two zero crossing points is calculated using the following formula (2); by comparing the actual sampling time T of the peak and valley points with the theoretical sampling time, the synchronous acquisition error of the power distribution terminal can be obtained;

[0035]

[0036] T = (T 01 +T 02 ) / 2 formula (2).

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) A system and method for synchronous acquisition performance testing of power distribution terminals are provided, filling the gap in the lack of a mature system for synchronous acquisition performance testing of power distribution terminals in China.

[0039] 2) The synchronization tester of this system can simultaneously test the synchronization acquisition performance of multiple power distribution terminals. These features give this system the following advantages:

[0040] a. Improve the testing efficiency of synchronous data acquisition performance of power distribution terminals. Provided the output power of the synchronous tester allows, multiple devices can be tested simultaneously; generally, more than 10 power distribution terminals can be tested concurrently.

[0041] b. Increase the comparative dimensions of synchronous data acquisition performance of power distribution terminals. When multiple power distribution terminals are tested simultaneously, the difference between the actual sampling time and the theoretical sampling time of the sampling points of the power distribution terminals can be compared, as can the difference between the actual sampling time of the sampling points of different terminals.

[0042] 3) The present invention proposes a method for testing the synchronous acquisition performance of power distribution terminals, which clarifies the quantitative evaluation index of the synchronous acquisition performance of power distribution terminals and can intuitively reflect the synchronous acquisition performance of power distribution terminals. Attached Figure Description

[0043] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0044] Appendix Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention;

[0045] Appendix Figure 2 This is a flowchart of a method implementation according to an embodiment of the present invention;

[0046] Appendix Figure 3 This is a schematic diagram of a calculation model for the actual sampling time of waveform sampling points according to an embodiment of the present invention. Detailed Implementation

[0047] As shown in the figure, a power distribution terminal synchronous data acquisition performance testing system is used to test power distribution terminals equipped with GPS / BeiDou time synchronization functions, including:

[0048] The GPS / BeiDou signal forwarding module is used to achieve indoor GPS / BeiDou signal coverage, enabling each power distribution terminal device under test to synchronize time via GPS / BeiDou signals in the test environment;

[0049] The synchronous test system is used to output specified multi-channel electrical quantities to the power distribution terminal under test at the exact second. The electrical quantities include voltage signals and current signals.

[0050] During the test, the synchronous test system tests each power distribution terminal one by one or tests multiple power distribution terminals at the same time; if multiple power distribution terminals are tested at the same time, for each voltage channel, the power distribution terminals are connected in parallel; for each current channel, the power distribution terminals are connected in series, so as to ensure that the voltage signals and current signals received by all the power distribution terminals participating in the test are completely consistent in time and amplitude;

[0051] The power distribution terminal to be tested records the waveforms of the multiple-channel electrical quantities and transmits the recorded waveforms to the test master station of the test system.

[0052] The test master station receives the waveforms uploaded by all the power distribution terminals to be tested and analyzes the waveforms to determine whether the synchronous acquisition performance of each power distribution terminal meets the requirements.

[0053] The GPS / Beidou signal forwarding module comprises an outdoor signal receiver, a wire and an indoor signal amplifier.

[0054] During the operation of the test system, the outdoor signal receiver is placed in an outdoor open area to receive GPS / Beidou signals; the wire is used to transmit the GPS / Beidou signals received by the outdoor signal receiver to the indoor signal amplifier; and the indoor signal amplifier amplifies the received GPS / Beidou signals to cover the entire indoor test environment, so that the test equipment with the GPS / Beidou time synchronization function can be time-synchronized through the GPS / Beidou signals in the indoor test environment.

[0055] The synchronous test system comprises a synchronous tester which is prepared by modifying a relay protection tester, and the functions of the synchronous tester include the functions of the relay protection tester before modification and an output interface which can ensure that all the output signals are output at the whole-second time.

[0056] When the power distribution terminal to be tested receives the multi-channel electrical quantity signals output by the synchronous test system, if the electrical quantity signals meet the recording wave starting condition, the recording wave function of the power distribution terminal is triggered, so that the power distribution terminal records the waveforms within at least 80 ms before the recording wave triggering time and within at least 160 ms after the recording wave triggering time, generates a recording wave file, and transmits the recording wave file to the test master station in the form of a waveform file.

[0057] After the test master station receives the waveform files uploaded by all the power distribution terminals to be tested, the recording wave files are analyzed.

[0058] The analysis method is as follows: according to the setting that the synchronous test system starts to output at the whole-second time and the period of the waveform is 20 ms, the theoretical phases of a plurality of recording wave sampling time points are calculated, and the theoretical phases are compared with the actual phases recorded by the recording wave file at the time points, so as to calculate the synchronous acquisition error of the power distribution terminal and determine whether the synchronous acquisition performance of the power distribution terminal meets the requirements.

[0059] The use method of the power distribution terminal synchronous acquisition performance test system is a power distribution terminal synchronous acquisition performance detection method, and includes the following steps.

[0060] Step S1, experiment environment building, including: experiment environment GPS / Beidou signal coverage, connecting the synchronous test system, the to-be-tested power distribution terminal, the test master station, and setting the to-be-tested power distribution terminal recording wave trigger condition.

[0061] Step S2, synchronous acquisition test, including: the synchronous test system outputs the test waveform, the to-be-tested power distribution terminal triggers the recording wave condition and records the test waveform, and the to-be-tested power distribution terminal uploads the recorded waveform to the test master station.

[0062] Step S3, detection result analysis, including: waveform analysis and result analysis.

[0063] Step S1 includes the following steps.

[0064] Step S1-1, experiment environment GPS / Beidou signal coverage: placing the outdoor signal receiver of the GPS / Beidou signal forwarding module in an outdoor open area, and connecting it with the indoor signal amplifier of the GPS / Beidou signal forwarding module by using a wire.

[0065] Step S1-2, connecting the synchronous test system, the to-be-tested power distribution terminal, and the test master station: connecting the synchronous test instrument and the power distribution terminals participating in detection in a manner of parallel connection of voltage channels and series connection of current channels; connecting the power distribution terminals and the test master station by using a network cable and an Ethernet switch, so as to ensure normal communication between the power distribution terminals and the test master station.

[0066] Step S1-3, setting the recording wave trigger condition of the to-be-tested power distribution terminal: setting the recording wave starting condition of each power distribution terminal participating in detection, so as to ensure that the power distribution terminal can normally record waves when the synchronous test system starts to output electrical quantity signals, and the power distribution terminal does not start recording waves when the synchronous test system does not output signals; if the synchronous test instrument simultaneously detects multiple power distribution terminals, the recording wave starting conditions of all the power distribution terminals need to be kept consistent.

[0067] Step S2 includes the following steps.

[0068] Step S2-1, the synchronous test system outputs the test waveform: first setting the test waveform that needs to be output by the synchronous test system, and then issuing a "start output" instruction; after receiving the instruction, the synchronous test system starts to output at the next whole second.

[0069] Step S2-2: Trigger the waveform recording condition and record the test waveform of the power distribution terminal under test: After the power distribution terminal under test receives the signal output by the synchronous test system, the waveform recording start condition is triggered, the terminal starts recording waveforms, records the waveforms at least 80ms before the waveform recording trigger time and at least 160ms after the trigger time, and generates a waveform recording file.

[0070] Step S2-3: The power distribution terminal under test sends the recorded waveform to the test master station: The power distribution terminal under test sends the recorded waveform file to the test master station via the IEC101 protocol or the IEC104 protocol.

[0071] Step S3 includes the following steps;

[0072] Step S3-1, Waveform Analysis: The test master station analyzes the waveform recording file to obtain the waveform of each voltage and current signal, including the amplitude and sampling time of each sampling point;

[0073] Step S3-2, Result Analysis: The test master station compares the phase of the actual sampling time point of the recorded waveform with the theoretical phase of the corresponding time point to draw test conclusions;

[0074] The theoretical phase value of the actual sampling time point of the recorded waveform is calculated according to the output of the synchronous tester at the whole second, with each waveform cycle being 20ms long.

[0075] Specifically, the peak and trough points of the waveform are selected as performance evaluation points for synchronous data acquisition at the distribution terminal. The actual sampling time at each peak and trough point is calculated and compared with the theoretical value of the sampling time. For example, Figure 3 As shown, first select two adjacent zero-crossing points x 01 and x 02 Calculate the time to zero. Assuming that actual sampling may not occur at the zero-crossing point, select the nearest sampling point x before or after the zero-crossing point. (n-1) x (n) and x (m-1) x (m) The actual sampling times corresponding to these sampling points are T. (n-1) T (n) and T (m-1) T (m) The zero-crossing time T of the waveform is approximately calculated using linear interpolation. 01 and T 02 T 01 The calculation formula for T is shown in formula (1) below. 02 The calculation formula and T 01 The calculation formula is similar;

[0076] The actual sampling time T of the peak and valley points between two zero-crossing points is calculated by the following formula (2); the synchronization collection error of the power distribution terminal is obtained by comparing the actual sampling time T of the peak and valley points with the theoretical sampling time;

[0077]

[0078] T = (T 01 +T 02 ) / 2 formula (2).

Claims

1. A power distribution terminal synchronous acquisition performance test system for testing a power distribution terminal with GPS / Beidou time synchronization function, characterized in that: Comprise: GPS / Beidou signal forwarding module, for realizing indoor GPS / Beidou signal coverage, so that each power distribution terminal equipment under test in the test environment through GPS / Beidou signal time synchronization; Synchronous test system, for outputting specified multi-channel electrical quantity to the power distribution terminal under test at the whole second moment, the electrical quantity including voltage signal, current signal; Test at the same time, test multiple power distribution terminals; if multiple power distribution terminals are tested at the same time, for each voltage channel, connect the power distribution terminal in parallel; for each current channel, connect the power distribution terminal in series, to ensure that the voltage signal and current signal received by all participating detection power distribution terminals are completely consistent in time and amplitude; The power distribution terminal under test records the multi-channel electrical quantity, and transmits the recorded waveform to the test master station of the test system; The test master station receives the waveform uploaded by all power distribution terminals under test, and analyzes the waveform to determine whether the synchronous acquisition performance of each power distribution terminal under test meets the requirements; The GPS / Beidou signal forwarding module comprises an outdoor signal receiver, a wire and an indoor signal amplifier; when the test system is working, the outdoor signal receiver is placed in an outdoor open area to receive GPS / Beidou signals; the wire is used to transmit the GPS / Beidou signals received by the outdoor signal receiver to the indoor signal amplifier; the indoor signal amplifier amplifies the received GPS / Beidou signals to cover the entire indoor test environment, ensuring that the test equipment with GPS / Beidou time synchronization function can perform time synchronization through GPS / Beidou signals in the indoor test environment; The synchronous test system comprises a synchronous tester prepared by modifying a relay protection tester, the functions of the synchronous tester include the functions of the relay protection tester before modification, and the output interface can ensure that all output signals are started at the whole second moment; When the power distribution terminal under test receives the multi-channel electrical quantity signal output by the synchronous test system, if the electrical quantity signal meets the recording wave starting condition, the recording wave function of the power distribution terminal is triggered, the power distribution terminal records the waveform within at least 80 ms before the recording wave trigger moment and at least 160 ms after the recording wave trigger moment, and generates a recording wave file, which is sent to the test master station in the form of a waveform file; After receiving the waveform file uploaded by all power distribution terminals under test, the test master station analyzes the recording wave file; the analysis method is as follows: according to the setting that the synchronous test system starts output at the whole second moment and the waveform period is 20 ms, the theoretical phase of several recording wave sampling time points is calculated, and the actual phase recorded at the time point in the recording wave file is compared, the synchronous acquisition error of the power distribution terminal is calculated, and whether the synchronous acquisition performance of the power distribution terminal meets the requirements is judged.

2. The use method of the power distribution terminal synchronous acquisition performance test system, which is a power distribution terminal synchronous acquisition performance detection method, characterized in that: The method comprises the following steps: Step S1, build the test environment, including: GPS / Beidou signal coverage in the test environment, connect the synchronous test system, the power distribution terminal under test, the test master station, and set the recording wave trigger condition of the power distribution terminal under test; Step S2, synchronous acquisition test, comprising: synchronously testing system outputting test waveform, the terminal under test triggering recording condition and recording test waveform, and the terminal under test uploading the recorded waveform to the test master station; Step S3, detection result analysis, comprising: waveform analysis and result analysis; Step S1 comprises the following steps; Step S1-1, GPS / Beidou signal coverage of experimental environment: placing the outdoor signal receiver of the GPS / Beidou signal transponder in an outdoor open area, and connecting it with the indoor signal amplifier of the GPS / Beidou signal transponder by wire; Step S1-2, connecting the synchronous test system, the terminal under test and the test master station: connecting the synchronous test instrument and the terminal under test in parallel in the voltage channel and in series in the current channel; connecting the terminal under test and the test master station by network cable and Ethernet switch to ensure normal communication between the terminal under test and the test master station; Step S1-3, setting the recording trigger condition of the terminal under test: setting the recording start condition of each terminal under test to ensure that the terminal under test can normally record when the synchronous test system starts to output electrical quantity signals, and the terminal under test does not start recording when the synchronous test system does not output signals; if the synchronous test instrument detects multiple terminals under test at the same time, the recording start conditions of all terminals under test need to be kept consistent; Step S2 comprises the following steps; Step S2-1, synchronous test system outputting test waveform: setting the test waveform to be output by the synchronous test system, and then issuing a "start output" instruction; after receiving the instruction, the synchronous test system starts to output at the next whole second; Step S2-2, the terminal under test triggering recording condition and recording test waveform: after receiving the signal output by the synchronous test system, the recording start condition of the terminal under test is triggered, and the terminal starts to record the waveform at least 80 ms before the recording trigger time and at least 160 ms after the recording trigger time, and generates a recording file; Step S2-3, the terminal under test uploading the recorded waveform to the test master station: the terminal under test sends the recording file to the test master station through IEC 101 protocol or IEC 104 protocol; Step S3 comprises the following steps; Step S3-1, waveform analysis: the test master station analyzes the recording file to obtain the waveform of each voltage and current signal, including the amplitude and sampling time of each sampling point; Step S3-2, result analysis: the test master station compares the phase of the actual sampling time point of the recording waveform with the theoretical phase of the corresponding time point to obtain the test conclusion; The theoretical phase value of the actual sampling time point of the recording waveform is calculated according to the whole second starting output of the synchronous test instrument, and each cycle of the waveform is 20 ms long; The peak and valley points of the selected waveform are selected as the power distribution terminal synchronous collection performance evaluation points, and the actual sampling time of the peak and valley points is compared with the sampling time theoretical value. Specifically, first, two adjacent zero-crossing points x 01 and x 02 are selected, the zero-crossing point time is calculated, the actual sampling time is not necessarily sampled at the zero-crossing point, then the nearest sampling points X n-1 , X n and X m-1 , X m before and after the zero-crossing point are selected, the actual sampling times corresponding to the sampling points are T n-1 , T n and T m-1 , T m , the waveform zero-crossing point times T 01 and T 02 are approximately calculated by using linear interpolation, the calculation formula of T 01 is shown in the following formula (1), and the calculation method of T 02 uses the calculation method of the calculation formula of T 01 . The actual sampling time T of the peak and valley points between two zero-crossing points is calculated by formula (2); by comparing the actual sampling time T of the peak and valley points with the theoretical sampling time, the synchronization acquisition error of the terminal under test can be obtained; T = (T 01 + T 02 ) / 2 Equation (2).

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