Circuit breaker closing resistor contact parameter measurement method based on high-frequency and direct-current high-voltage synthesis signal

Abstract

The invention discloses a circuit breaker closing resistor contact parameter measurement method based on a high-frequency and direct-current high-voltage synthesis signal, and relates to the technical field of circuit breaker resistance measurement, and the method comprises the steps: finely calculating a measured impedance value of an nth cycle, a measured resistance value of the nth cycle and a measured capacitance value of the nth cycle through a high-frequency method; direct-current high-voltage method dynamic measurement: applying direct-current high voltage to two sides of a fracture of the circuit breaker, synchronously acquiring high-voltage voltage and high-voltage current waveforms in a closing process, and calculating a real-time resistance value of a closing resistor point by point; and synchronizing and fusing data and the like. The high-precision impedance analysis capability of a high-frequency method and the real dynamic response characteristic of a high-voltage method are fused, the limitation of a single method is overcome, test data are comprehensive, the precision is high, and the dynamic property is achieved. Through the data fusion technology, all key curves are integrated in the same view, thereby greatly facilitating the visual analysis and fault diagnosis of the working state of the closing resistor by engineers, and being visual and efficient.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker resistance measurement technology, specifically a method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage. Background Technology

[0002] 500kV and above ultra-high voltage circuit breakers are equipped with closing resistors. The failure rate of closing resistors and transmission components has always been significantly higher than that of other components of the circuit breaker. Moreover, failure of closing resistor components usually causes flashover discharge inside tank-type circuit breakers or GIS, or the porcelain bushing of porcelain column circuit breakers to explode, resulting in serious consequences.

[0003] The closing resistors of ultra-high voltage and extra-high voltage circuit breakers are generally two sets connected in series. During the closing process, the contacts of the two closing resistors move synchronously and each exhibits a bounce. Currently, the low-voltage DC voltage drop method and the separate high-frequency signal measurement method are commonly used to measure the operating characteristics of the closing resistors of ultra-high voltage and extra-high voltage circuit breakers.

[0004] The low-voltage DC voltage drop method has two main problems: First, the contact length of the closing resistors at each break point of an ultra-high voltage (UHV) circuit breaker is very short simultaneously. The closing resistance tester using the DC voltage drop method can only detect the closing resistance when two closing resistor contacts are in contact simultaneously; when the contacts bounce, the pre-connection time cannot be accurately measured. Second, due to the high electromagnetic interference in UHV substations, the resistance value of the circuit breaker closing resistor is greatly affected by the induced voltage, making accurate resistance measurement impossible.

[0005] On the other hand, measuring the closing resistance of ultra-high voltage circuit breakers using a separate high-frequency signal method also has limitations. Since the closing resistance of a circuit breaker is generally composed of two sets connected in series, and each closing resistance contact is connected in parallel with a voltage-equalizing capacitor, when measuring the closing resistance using a separate high-frequency signal output, the follow current between the contacts during the closing process is unclear, the measured waveform is significantly affected by stray capacitance, and the timing of the closing resistance's engagement and disengagement is not very distinct.

[0006] Therefore, there is an urgent need for a method to measure the contact parameters of circuit breaker closing resistance, which can accurately reconstruct the trend of resistance value change and the timing of connection, conduct multi-dimensional status assessment of the actual operating conditions of ultra-high voltage and extra-high voltage, and improve the fault early warning capability. Summary of the Invention

[0007] To address the aforementioned problems, the purpose of this invention is to provide a method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage includes the following steps:

[0010] ① High-frequency method for precise calculation of the measured impedance value Z of the nth cycle n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n ;

[0011] ② Dynamic measurement using DC high voltage method: Apply DC high voltage to both sides of the circuit breaker break, synchronously collect the high voltage and high voltage current waveforms during the closing process, and calculate the real-time resistance value R of the closing resistor point by point. t ;

[0012] ③ Data synchronization and fusion:

[0013] Let M be the number of data points for the high-frequency method and N be the number of data points for the high-voltage method, where N > M;

[0014] Calculate the expansion factor K = N / M;

[0015] Each data point of the high-frequency method is copied K times to generate a new data sequence of length N.

[0016] Preferably, the specific steps of step ① are as follows: during the circuit breaker closing process, a high-frequency test signal is injected into the primary circuit, and the voltage and current waveforms of the circuit are collected synchronously, and then analyzed using each signal cycle as the basic unit.

[0017] Preferably, when analyzing using each signal cycle as the basic unit, the number of cycles is calculated based on the zero-crossing points of the waveform. n The phase angle θ between voltage and current for each cycle n Root mean square voltage U rms(n) and the root mean square value of current I rms(n) Then, impedance decomposition is used to calculate the measured impedance value Z of the nth cycle. n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n .

[0018] Preferably,

[0019] Among them U (n) Let N be the instantaneous voltage value at the sampling point in the nth cycle. U K represents the sequence number of high-frequency voltages within that period. u This refers to the turns ratio of the voltage sensor.

[0020] Preferably,

[0021] Where I(n) Let N be the instantaneous current value at the sampling point in the nth cycle. I K represents the sequence number of high-frequency currents within that period. i This refers to the transformation ratio of the current sensor.

[0022] Preferably, the measured impedance value Z of the nth cycle n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n The calculation formula is as follows:

[0023] Impedance value:

[0024] Resistance value: Where θ n This represents the phase angle between voltage and current.

[0025] Capacitance value: Where ω is the angular frequency.

[0026] Preferably, in step ②, during the dynamic measurement using the DC high-voltage method, the real-time resistance value R of the closing resistor is calculated. t The calculation formula is R t =U t / I t ;where U t It is a DC high voltage, I t It is a DC high voltage current.

[0027] Preferably, step ②, the dynamic measurement using the DC high voltage method, further includes determining the closing resistor connection time, the resistor break closing time, and the main break closing time based on the occurrence time of the high voltage current.

[0028] Preferably, step ③ further includes fusing and displaying the synchronized high-frequency method data and high-voltage method data on the same time axis to generate a comprehensive curve.

[0029] Preferably, the high-frequency data is the measured impedance value Z of the nth cycle. n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n The high-voltage method data is the real-time resistance value R. t .

[0030] The present invention has the following advantages over the prior art:

[0031] This invention presents a method for measuring circuit breaker closing resistance contact parameters based on a composite signal from high-frequency and DC high-voltage sources. This method provides multi-dimensional analytical data by obtaining the resistance value, capacitive component, and precise engagement time of the closing resistance in a single test. This method integrates the high-precision impedance analysis capabilities of the high-frequency method with the realistic dynamic response characteristics of the high-voltage method, overcoming the limitations of single methods. The test data is comprehensive, highly accurate, and dynamic. Furthermore, this method integrates all key curves into a single view through data fusion technology, greatly facilitating engineers' intuitive analysis and fault diagnosis of the closing resistance's operating status, making it both intuitive and efficient. On the other hand, by introducing configurable sensor ratios and multi-stage calibration coefficients, it adapts to different field conditions, further ensuring the accuracy and reliability of the measurement results. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating the overall process of the method of the present invention.

[0033] Figure 2 This is a waveform diagram of simultaneous output testing using the high-frequency method and the high-voltage method in an embodiment of the present invention.

[0034] Figure 3 This is a schematic diagram showing the zero-crossing points of the high-frequency voltage and current waveforms in an embodiment of the present invention.

[0035] Figure 4 This is a schematic diagram of the measurement circuit of the method of the present invention;

[0036] Figure 5 This is a schematic diagram of the AC impedance and DC resistance curves obtained by the high-frequency method and the high-voltage method in the embodiments of the present invention, which change over time.

[0037] Figure Labels

[0038] C1 is the first voltage equalizing capacitor, C2 is the second voltage equalizing capacitor, K1 is the first closing resistor break, R1 is the first closing resistor, DK1 is the first main break, K2 is the second closing resistor break, R2 is the second closing resistor, DK2 is the second main break, DC power supply, AC power supply. Detailed Implementation

[0039] The purpose of this invention is to provide a method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage, which is achieved through the following technical solution:

[0040] The following section introduces the low-voltage DC voltage drop method and the high-frequency high-voltage fusion method.

[0041] The low-voltage DC drop method applies a DC voltage across the circuit breaker contacts and measures the voltage and current during the closing process, calculating the resistance value based on Ohm's law. It directly reflects the dynamic process at the moment the closing resistance is engaged. However, when the circuit breaker experiences significant bounce during closing, the current cannot continue flowing, making it impossible to measure the closing resistance value. Furthermore, the measurement information is limited; it can only measure the resistance value and cannot distinguish capacitive components in the circuit (such as the voltage-equalizing capacitor at the contacts), potentially affecting the judgment of the true resistance state.

[0042] The high-frequency, high-voltage fusion method applies a DC high voltage to both sides of the circuit breaker's contact, directly measuring the voltage and current during the closing process. The resistance value is calculated using Ohm's law. Simultaneously, a high-frequency test signal is injected into the primary circuit of the circuit breaker, and the resistance and capacitance components are decomposed by measuring the amplitude and phase of the impedance. The high-voltage method improves current carrying capacity and directly reflects the dynamic process at the moment the closing resistor is engaged. The high-frequency method offers high measurement accuracy, effectively separates resistance and capacitance, and has strong anti-interference capabilities. Combining these two methods provides accurate impedance decomposition through the high-frequency method and a true dynamic process through the high-voltage method; the two methods complement each other.

[0043] Both methods have their advantages and disadvantages, but because their measurement principles, data structures, and sampling rates are completely different, the measurement data cannot be directly and effectively compared and comprehensively analyzed on the same time axis. Engineers cannot simultaneously obtain high-precision resistance and capacitance values ​​and true dynamic time series, making it difficult to make a comprehensive and accurate assessment of the overall working status of the closing resistor.

[0044] The present invention will be further described below with reference to specific embodiments.

[0045] Example 1

[0046] A method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage includes the following steps:

[0047] ① High-frequency method for precise calculation of the measured impedance value Z of the nth cycle n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n ;

[0048] ② Dynamic measurement using DC high voltage method: Apply DC high voltage to both sides of the circuit breaker break, synchronously collect the high voltage and high voltage current waveforms during the closing process, and calculate the real-time resistance value R of the closing resistor point by point. t ;

[0049] ③ Data synchronization and fusion:

[0050] Let M be the number of data points for the high-frequency method and N be the number of data points for the high-voltage method, where N > M;

[0051] Calculate the expansion factor K = N / M;

[0052] Each data point of the high-frequency method is copied K times to generate a new data sequence of length N.

[0053] The specific steps of step ① are as follows: During the circuit breaker closing process, a high-frequency test signal is injected into the primary circuit, and the voltage and current waveforms of the circuit are collected synchronously. Then, the analysis is performed using each signal cycle as the basic unit.

[0054] When analyzing a signal cycle as the basic unit, the phase angle θ between the voltage and current of each cycle is calculated based on the zero-crossing point of the waveform. n Root mean square voltage U rms(n) and the root mean square value of current I rms(n) Then, impedance decomposition is used to calculate the measured impedance value Z of the nth cycle. n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n .

[0055] The measured impedance value Z of the nth cycle n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n The calculation formula is as follows:

[0056] Impedance value:

[0057] Resistance value: Where θ n This represents the phase angle between voltage and current.

[0058] Capacitance value: Where ω is the angular frequency.

[0059] Step ② During dynamic measurement using the DC high-voltage method, calculate the real-time resistance value R of the closing resistor. t The calculation formula is R t =U t / I t ;where U t It is a DC high voltage, I t It is a DC high voltage current.

[0060] Step ② DC high voltage method dynamic measurement also includes determining the closing resistor connection time, the resistor break closing time, and the main break closing time based on the occurrence time of the high voltage current.

[0061] Step ③ also includes fusing and displaying the synchronized high-frequency method data and high-voltage method data on the same time axis to generate a comprehensive curve.

[0062] The high-frequency method data is the measured impedance value Z of the nth cycle. n The measured resistance value R of the nth cycle n The measured capacitance value C of the nth cycle n The high-voltage method data is the real-time resistance value R. t .

[0063] Example 2

[0064] A method for measuring the closing resistance contact parameters of a circuit breaker based on a composite signal of high frequency and DC high voltage, such as... Figure 1 As shown, it includes the following steps:

[0065] By applying a 100kHz high-frequency signal to the primary circuit, and the high-frequency power supply output frequency being f (in Hz), we have ω = 2πf. By measuring the waveforms of the circuit current I0 and voltage U0, we can analyze and calculate the circuit impedance and phase angle.

[0066] A high-voltage signal is synchronously applied in the primary circuit. The output range of the high-voltage source is 0–4kV, ensuring uninterrupted current flow during the closing resistor connection process. The circuit breaker performs a closing operation, and the voltage U across the circuit breaker is measured. t and the waveform I of the current passing through it t Calculate the closing resistance value R. t By combining the coil current curve, the activation time of the closing resistor and the operating time of the main contacts can be analyzed.

[0067] like Figure 2 The waveform diagram shown is the waveform of the test when the high-frequency source and the high-voltage source are output simultaneously.

[0068] Based on the recorded test waveforms, by selecting the nth peak of the high-frequency voltage signal and the nth peak of the high-frequency current in the same direction, the phase angle θ between the voltage and current can be calculated respectively. n Root mean square value of high frequency voltage U rms(n) Root mean square current I rms(n) impedance Z n and capacitor C n .

[0069] like Figure 3 As shown, find the adjacent zero-crossing points P1(t) in the same direction on the voltage and current waveforms. ip1 ), P1′(t up1 (1) Calculate the phase angle θ between the voltage and current in the nth cycle. n The unit is °:

[0070]

[0071] T is the output cycle of a high-frequency power supply, in milliseconds.

[0072] t ip(n) t is the time when the high-frequency current crosses zero. up(n) This refers to the moment when the high-frequency voltage crosses zero.

[0073] (2) Calculate the root mean square value U of the high-frequency voltage of the nth cycle. rms(n) The unit is V:

[0074]

[0075] Among them U (n) Let N be the instantaneous voltage value at the sampling point in the nth cycle (i.e., the voltage value corresponding to each sequence in the nth cycle). U K represents the sequence number of high-frequency voltages within that period. u The turns ratio K is required because the high-frequency voltage is measured by the voltage sensor. u Converted to the actual voltage on the primary side;

[0076] (3) Calculate the root mean square I of the high-frequency current in the nth cycle. rms(n) The unit is A:

[0077]

[0078] Where I (n) Let N be the instantaneous current value at the sampling point in the nth cycle (i.e., the current value corresponding to each sequence in the nth cycle). I K represents the sequence number of high-frequency currents within that period. i The turns ratio K is required because the high-frequency current is measured by the current sensor. i Converted to actual primary current;

[0079] (4) Calculate the impedance Z of the nth cycle. n The unit is Ω:

[0080]

[0081] (5) Calculate the resistance value R of the nth cycle. n The unit is Ω:

[0082]

[0083] (6) Calculate the angular frequency ω:

[0084]

[0085] (7) Calculate the capacitance C of the nth cycle. n The unit is F:

[0086]

[0087] Let T2 be the closing time of the resistor break and T4 be the closing time of the main break. Then, the time for the closing resistor to be engaged is:

[0088] T5 = T4 - T2;

[0089] The resistance value R of the resistor during this period of time. t , for the voltage U during this period t With current I t The ratio, i.e., the closing resistor value

[0090] like Figure 4 The diagram shows the measurement circuit principle of the method of the present invention. The diagram shows a double-break high-voltage circuit breaker, which consists of two sets of breaks connected in series. Each set of breaks includes a voltage equalizing capacitor, a closing resistor, a resistance break, and a main break. The closing resistor and the resistance break are connected in series to form a closing resistor branch. The voltage equalizing capacitor, the closing resistor branch, and the main break are connected in parallel. High-frequency signals and high-voltage signals are applied in the measurement circuit.

[0091] For high-frequency signals, capacitors pass high frequencies and block low frequencies, while resistors impede current flow. For high-voltage signals, capacitors block DC and pass AC; when both the resistor and main circuit breakers are open, no current flows through the circuit. Based on circuit characteristics and the closing resistor process, the process of applying the closing resistor can be understood:

[0092] When the first closing resistor break point K1 is closed, the second closing resistor break point K2 is open, and the main break point is in the open position, the circuit impedance is the first equalizing capacitor C1 connected in parallel with the first closing resistor R1, and then connected in series with the second equalizing capacitor C2; if the first closing resistor break point K1 is open, the second closing resistor break point K2 is closed, and the main break point is in the open position, the circuit impedance is the second equalizing capacitor C2 connected in parallel with the second closing resistor R2, and then connected in series with the first equalizing capacitor C1.

[0093] The first closing resistor break point K1 is closed, the second closing resistor break point K2 is closed, the main break point is in the open position, and the circuit impedance is the first equalizing capacitor C1 connected in parallel with the first closing resistor R1, the second equalizing capacitor C2 connected in parallel with the second closing resistor R2 and then connected in series.

[0094] When the first closing resistor break point K1 and the second main break point DK2 are closed, the circuit impedance is the first equalizing capacitor C1 and the first closing resistor R1 connected in parallel; when the second closing resistor break point K2 and the first main break point DK1 are closed, the circuit impedance is the second equalizing capacitor C2 and the second closing resistor R2 connected in parallel.

[0095] The first closing resistor break point K1 is open, the second closing resistor break point K2 is open, and the main break point is in the closed position. At this time, the circuit impedance is the circuit resistance of the main break point, which is in the micro-ohm range.

[0096] Example 3

[0097] By applying a 100kH in the primary circuit z The high-frequency signal, after the circuit breaker is closed, is analyzed based on the test data. Table 1 shows the derived raw data.

[0098] Table 1. Original data after applying high-frequency signal.

[0099]

[0100]

[0101]

[0102]

[0103]

[0104] Calculate the phase angle θ between voltage and current n :

[0105]

[0106] because f = 100kHz, therefore T = 0.01ms. Substituting this into the formula...

[0107]

[0108] By analogy, the angle of each cycle θ2, θ3, θ4... can be calculated.

[0109] Calculate the root mean square value of high-frequency voltage U rms(n) :

[0110]

[0111] Among them U (n) Let N be the instantaneous voltage value at the sampling point in the nth cycle (i.e., the voltage value corresponding to each sequence in the nth cycle). U K represents the sequence number of high-frequency voltages within that period. u The turns ratio of the voltage sensor.

[0112] Taking the data from the first cycle in Table 1 as an example, that is, when n is 1, find the first point P1′(t) up1 At that time, in Table 1

[0113] At the time of -39.9889ms in line 61, the corresponding voltage value is U1 = 0.6867293mV;

[0114] At the time of -39.9887ms in line 62, the corresponding voltage value is U2 = 12.97155mV;

[0115] At the time of -39.9885ms in line 63, the corresponding voltage value is U3 = 24.95116mV;

[0116] And so on,

[0117] At time 39.9791ms in line 110, the corresponding voltage value is U. 50 = -8.790134V;

[0118] The time at line 111-39.9789ms is the zero-crossing point of the next cycle, so it is included in the calculation of the next cycle;

[0119] Find the second point P2′(t) up2 At the time shown in Table 1

[0120] At time 39.9789ms (line 111), the corresponding voltage value is U. 51 =3.677817mV;

[0121] At time 39.9787ms in line 112, the corresponding voltage value is U. 52 =15.99316mV;

[0122] At time 39.9785ms in line 113, the corresponding voltage value is U. 52 =27.95751mV;

[0123] And so on,

[0124] At time 39.9693ms (line 159), the corresponding voltage value is U. 99 = -18.49591mV;

[0125] At time 39.9691ms (line 160), the corresponding voltage value is U. 100 = -6.04332mV;

[0126] Therefore, we get U rms(2) By calculating in sequence, we can obtain

[0127]

[0128] Here K u The transformation ratio of the high-frequency voltage sensor is set to 245, which can be substituted into the formula for calculation.

[0129] U rms(1) =17.2259V;

[0130] Urms(2) =17.2112V;

[0131] Calculate the root mean square current I of the high-frequency current rms(n) :

[0132]

[0133] I rms(1) =0.1352 / K i A;

[0134] Where I (n) Let N be the instantaneous current value at the sampling point in the nth cycle (i.e., the current value corresponding to each sequence in the nth cycle). I K is the sequence number of high-frequency currents within this period. i The transformation ratio of the current sensor;

[0135] Referring to the calculation method of the root mean square of high-frequency voltage, I can be obtained. rms(1) I rms(2) I rms(3) ..., here K i The sensor ratio for the high-frequency current measurement channel is set to 22, which can be substituted into the formula for calculation.

[0136] I rms(1) =0.1352 / K i A = 0.1352 / 22A = 0.0061A;

[0137] I rms(2) =0.0061A;

[0138] I rms(3) =0.0061A;

[0139] And so on.

[0140] Calculate impedance Z n :

[0141]

[0142] Substituting the calculated root mean square of high-frequency voltage and root mean square of high-frequency current into the formula, we obtain...

[0143]

[0144] Calculate the resistance value R n :

[0145]

[0146] And so on.

[0147]

[0148] Calculate the angular frequency ω:

[0149]

[0150] Calculate capacitance C n :

[0151]

[0152] And so on.

[0153]

[0154] A 3kV high-voltage signal is synchronously applied in the primary circuit to ensure uninterrupted current flow during the closing resistor connection process. The circuit breaker performs a closing operation, and the voltage U across the circuit breaker is measured. t and the waveform I of the current passing through it t Calculate the closing resistance value R. t Analysis of the test data shows that...

[0155] Calculate the closing resistance value R t :

[0156]

[0157] And so on:

[0158]

[0159] Combining high-frequency and high-voltage methods for calculating and analyzing closing resistance, waveforms of AC impedance and DC resistance versus time are plotted based on the calculated parameters.

[0160] Let T2 be the closing time of the resistor break and T4 be the closing time of the main break. Then, the time for the closing resistor to be engaged is:

[0161] T5 = T4 (main circuit breaker closing time) - T2 (resistor circuit breaker closing time);

[0162] T5 = 28.05 - 0.06 = 27.99 ms.

[0163] When high-voltage and high-frequency sources are tested simultaneously, the data from the high-frequency method is calculated and plotted on a periodic basis, while the high-voltage method is calculated and plotted on a time-by-time basis. Therefore, the data volumes of the two methods are asynchronous. To achieve synchronized data plotting, the high-frequency method test data needs to be copied and expanded. In actual testing, the high-voltage method measures resistance data N = 1,000,000 data points, and the high-frequency method measures impedance data M = 20,000 data points. Therefore, the expansion factor K = 1,000,000 / 20,000 = 50, expanding the length of the high-frequency impedance data from 20,000 to 1,000,000 data points to achieve data synchronization. Figure 5 As shown, the method of this invention integrates and displays the calculation results of multiple parameters on the same time axis:

[0164] High-frequency impedance Zn: It is represented by a relatively smooth but slightly stepped curve, showing the high precision and continuous change trend of AC impedance throughout the entire closing process.

[0165] High-voltage resistor Rh: It is represented by a delicate curve with rich details, especially showing a sharp drop at time t2, which accurately captures the instantaneous dynamics of the closing resistor being connected.

[0166] (1) Based on the principle of the measurement circuit, time T1 is the moment when the closing resistor K1 just closes. The time from T1 to T2 is the process of the closing resistor R1 being put into operation. At this time, the circuit impedance is the impedance of the equalizing capacitor C1 and the closing resistor R1 connected in parallel, and then connected in series with C2.

[0167] In this process, there is no current in the DC high-voltage method measurement circuit, and the high-voltage method measures resistance Rh close to infinity. In this process, the AC high-frequency method is based on the RC effect, and the waveform of the measured impedance data reflects the process of resistor R1 being connected.

[0168] (2) Based on the principle of the measurement circuit, time T2 is the moment when the closing resistor K2 just closes. From T1 to T3, the closing resistors R1 and R2 are both engaged. At this time, the closing resistors K1 and K2 are closed, and the main contact is in the open position. The circuit impedance is the equalizing capacitor C1 connected in parallel with the closing resistor R1, and the equalizing capacitor C2 connected in parallel with the closing resistor R2 and then connected in series.

[0169] In this process, the DC high-voltage method measurement circuit forms a path and establishes current. At this time, the measured resistance waveform is the sum of the resistances of R1 and R2. The waveform of the resistance measured by the high-voltage method reflects the process of R1 and R2 being connected. In this process, the AC high-frequency method is based on the RC effect. The impedance waveform measured by the high-frequency method reflects the process of R1 and R2 being connected.

[0170] (3) Based on the principle of the measurement circuit, time T3 is the moment when the main break K1 just closes, and time T1-T4 is the time when the closing resistor breaks K1 and K2 close and the main break DK1 closes. The circuit impedance is the parallel connection of the equalizing capacitor C2 and the closing resistor R2.

[0171] In this process, the DC high-voltage method measurement circuit forms a path and establishes current. At this time, the test resistance waveform is the R2 resistance. The waveform of the resistance data measured by the high-voltage method reflects the process of R2 being connected. In this process, the AC high-frequency method is based on the RC effect. The impedance waveform measured by the high-frequency method reflects the process of R2 being connected.

[0172] (4) Based on the principle of the measurement circuit, T4 is the moment when the main break K2 just closes. At this time, the closing resistor breaks K1 and K2 are closed, and the main breaks DK1 and DK2 are closed. The circuit impedance is the circuit resistance of the main break, which is in the micro-ohm range.

[0173] The schematic diagrams of AC impedance and DC resistance changing with time, obtained by high-frequency method and high-voltage method, can reflect the state of each break point during the connection of the closing resistor, and fully reflect the connection process of the closing resistor.

Claims

1. A method for measuring parameters of closing resistor contacts of a circuit breaker based on a high-frequency and DC high-voltage combined signal, characterized in that: Comprising the following steps: ① high frequency method fine calculation of the nth harmonic measured impedance value Z n , the nth harmonic measured resistance value R n , and the nth harmonic measured capacitance value C n ; ② Direct current high voltage method dynamic measurement: direct current high voltage is applied on both sides of the breaker, high voltage voltage and high voltage current waveform during closing are synchronously collected, real-time resistance value R of the closing resistor is calculated point by point t ; ③ Data synchronization and fusion: Let the number of high-frequency method data points be M, and the number of high-voltage method data points be N, and N > M; Calculate the expansion multiple K = N / M; Repeat each data point of the high-frequency method K times to generate a new data sequence with a length of N.

2. The circuit breaker closing resistor contact parameter measurement method based on a high frequency and DC high voltage combined signal according to claim 1, characterized in that: The specific steps of step ① are: during the closing process of the circuit breaker, a high-frequency test signal is injected into the primary circuit, the voltage and current waveforms of the circuit are synchronously collected, and then analysis is performed with each signal cycle as the basic unit.

3. The method for measuring the parameters of the closing resistor contact of a circuit breaker based on a high-frequency and DC high-voltage combined signal according to claim 2, characterized in that: When analyzing per signal cycle as a basic unit, based on the zero-crossing point of the waveform, the phase angle θ of the voltage and current of the nth cycle is calculated n , the root mean square value of the voltage U rms(n) and the root mean square value of the current I rms(n) , and then the impedance decomposition calculates the measured impedance value Z n of the nth cycle, the measured resistance value R n of the nth cycle and the measured capacitance value C n of the nth cycle.

4. The circuit breaker closing resistance contact parameter measurement method based on a high-frequency and DC high-voltage combined signal according to claim 3, characterized in that: wherein U (n) is the instantaneous voltage value of the sampling point in the nth cycle, N U is the number of series of high-frequency voltage in the cycle; K u is the transformation ratio of the voltage sensor.

5. The circuit breaker closing resistance contact parameter measurement method based on a high-frequency and DC high-voltage combined signal according to claim 3, characterized in that: where I (n) is the instantaneous current value of the sampling point in the nth cycle, N I is the number of series of high-frequency currents in the cycle; K i is the transformation ratio of the current sensor.

6. The method for measuring the parameters of the closing resistor contact of a circuit breaker based on a high-frequency and DC high-voltage combined signal according to claim 3, characterized in that: the measured impedance value Z of the nth harmonic n the measured resistance value R of the nth harmonic n and the measured capacitance value C of the nth harmonic n The calculation formula is as follows: Impedance values: Resistance value: where θ n is the phase angle of the voltage and current; Capacitance value: where ω is the angular frequency.

7. The circuit breaker closing resistor contact parameter measurement method based on a high frequency and DC high voltage combined signal according to claim 1, characterized in that: Step 2: When the dynamic measurement of the DC high voltage method is performed, the real-time resistance value R of the closing resistor is calculated t , and the calculation formula is R t = U t / I t ; wherein U t is the DC high voltage, and I t is the DC high voltage current.

8. The circuit breaker closing resistor contact parameter measurement method based on a high frequency and DC high voltage combined signal according to claim 1, characterized in that: Step ② DC high-voltage method dynamic measurement further includes judging the closing resistance input time, the closing time of the resistance joint, and the closing time of the main joint according to the occurrence time of the high-voltage current.

9. The circuit breaker closing resistor contact parameter measurement method based on a high frequency and DC high voltage combined signal according to claim 1, characterized in that: Step ③ further includes fusing and displaying the synchronized high-frequency method data and the high-voltage method data on the same time axis to generate a comprehensive curve graph.

10. The circuit breaker closing resistor contact parameter measurement method based on a high frequency and DC high voltage combined signal according to claim 9, characterized in that: The high frequency method data is the measured impedance value Z of the nth harmonic n , the measured resistance value R of the nth harmonic n , and the measured capacitance value C of the nth harmonic n The high voltage method data is the real-time resistance value R t .

Images