CN112034309A - Partial discharge identification method for high-voltage switch cabinet - Google Patents
Partial discharge identification method for high-voltage switch cabinet Download PDFInfo
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- CN112034309A CN112034309A CN202010739929.1A CN202010739929A CN112034309A CN 112034309 A CN112034309 A CN 112034309A CN 202010739929 A CN202010739929 A CN 202010739929A CN 112034309 A CN112034309 A CN 112034309A
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The invention discloses a partial discharge identification method for a high-voltage switch cabinet, belonging to the technical field of live-line detection of high-voltage equipment. Firstly, a module (1) for measuring frequency and phase of voltage of a switch cabinet is connected with a square wave generating device (2); the transient ground voltage sensor (3) is fixed on the high-voltage switch cabinet, and the partial discharge measurement system (4) is connected with the transient ground voltage sensor (3); collecting partial discharge signals of the operating high-voltage switch cabinet; specifically, a superimposed square wave form is adopted, a partial discharge signal of the switch cabinet is acquired through a transient ground voltage sensor, whether the partial discharge signal is a discharge signal or not is judged according to the characteristics of the tested signal, and the position of partial discharge is analyzed; the invention solves the problems of large interference signal and difficult correct identification in the partial discharge detection of the high-voltage switch cabinet at present; partial discharge which can endanger insulation safety exists in the switch cabinet, and the switch cabinet has important significance for timely overhauling and finding insulation weak links.
Description
Technical Field
The invention belongs to the technical field of live-line detection of high-voltage equipment, and particularly relates to a partial discharge identification method for a high-voltage switch cabinet.
Background
The switch cabinet is a widely used switch device, and the accident rate of the switch cabinet is relatively high due to various problems in design, manufacture, operation, maintenance and the like. In a power distribution network, a switch cabinet runs in severe environments such as high temperature, high voltage and humidity for a long time, and the insulativity of the switch cabinet is easily damaged, so that partial discharge is caused. The method has the advantages of monitoring the partial discharge of the switch cabinet, diagnosing the insulation fault accurately in an early stage, reducing the equipment accident loss and unplanned shutdown, enhancing the operation capacity, and improving the equipment operation and maintenance management level, and has very important significance.
When partial discharge possibly endangering insulation safety exists in a switch cabinet, the partial discharge is determined by adopting a proper method, the method has important significance for timely overhauling and finding insulation weak links, the current means for accurately judging the partial discharge is lacked, in the current high-voltage switch cabinet partial discharge detection, interference signals are large and difficult to correctly identify, and the success rate of identifying discharge and interference is not high.
Disclosure of Invention
The invention aims to provide a partial discharge identification method for a high-voltage switch cabinet; the method is characterized in that a module 1 for measuring frequency and phase of voltage of a switch cabinet is connected with a square wave generating device 2; the transient ground voltage sensor 3 is fixed on the high-voltage switch cabinet, and the partial discharge measurement system 4 is connected with the transient ground voltage sensor 3; collecting partial discharge signals of the operating high-voltage switch cabinet; specifically, a superimposed square wave form is adopted, a partial discharge signal of the switch cabinet is acquired through a transient ground voltage sensor, whether the partial discharge signal is a discharge signal or not is judged according to the characteristics of the tested signal, and the position of partial discharge is analyzed; the method specifically comprises the following steps:
step 1: under the condition of live operation of the switch cabinet, detecting signals by using a transient earth voltage sensor and a local discharge measuring system, and setting the maximum amplitude of the absolute value of the detected signals as Y;
step 2: acquiring the change condition of sinusoidal voltage of high-voltage electricity of the switch cabinet along with time, calculating the frequency f and the phase A of the sinusoidal voltage, shaping to generate square signals with the same frequency f (unit is Hz) and the same phase A, wherein the high level of the square signals is 1-10V, and the low level of the square signals is 0;
and step 3: injecting the square wave signal to the ground on the shell of the switch cabinet, wherein the ground is the same as the ground of the output signal of the transient voltage sensor in the step 1;
and 4, step 4: detecting signals by using the same sensor and measuring system as in the step 1;
and 5: sampling the test signal obtained in the step (4), wherein the signal value of each time point after sampling is called as sampling data, and the total time length of sampling is not less than 10 seconds and is an integral multiple of the reciprocal of the f in the step (2);
step 6: dividing the total time of the sampling in the step 4 into n time segments with the length of 10 microseconds from the time point of starting timing of measurement, wherein the number of the time segments is n-1, 2 and 3 … … in sequence;
and 7: sampling the amplitude of the absolute value of the measured signal in each time period, if the amplitude of one absolute value is higher than Y/2, then all data in the time period is called a valid pulse, recording the time period number n corresponding to each valid pulse, and if the n is larger than 100000/f, subtracting 100000/f from n until n is smaller than 100000/f; wherein 100000 is derived from the reciprocal of 10 microseconds;
and 8: counting the number of all effective pulses in the total time length of the sampling in the step 4, and recording the number as N;
and step 9: according to the time period number n corresponding to the effective pulse in the step 7, counting the number of the effective pulses which are in accordance with a characteristic interval 10000/(18 f) < n <20000/(9 f), and recording the number as M to represent the number of points of the effective pulses in the discharge characteristic phase;
step 10: if M/N is greater than 0.5, considering that partial discharge exists in the switch cabinet in the step 1, closely paying attention to the insulation condition or performing maintenance, if 0.3< M/N <0.5, considering that partial discharge possibly exists in the switch cabinet in the step 1, and intensively observing, if M/N <0.3, considering that partial discharge does not exist in the switch cabinet in the step 1, and ensuring that the insulation condition is safe;
the module for measuring frequency and phase is formed by connecting a shaping circuit, a counter circuit and an output part in sequence, wherein the shaping circuit is used for shaping a sine periodic signal into a square signal; the counter circuit obtains the zero crossing phase and the period of the signal through zero crossing timing and clock counting, and the zero crossing phase and the period are output by the output part.
The transient ground voltage sensor is a transient ground voltage (TEV) sensor based on a coupling capacitance principle;
the partial discharge measurement system is a partial discharge tester or oscilloscope with the sampling frequency not lower than 20MHz, and the input impedance is not lower than 1 megaohm.
The invention has the advantages that the part which can endanger the insulation safety in the switch cabinet can be found in time, the partial discharge of the switch cabinet is monitored, the insulation fault is diagnosed accurately in early stage, and the switch cabinet is overhauled in time; the method has the advantages of reducing equipment accident loss and unplanned shutdown, enhancing operation capacity, and improving equipment operation and maintenance management level, and has very important significance.
Drawings
Fig. 1 is a schematic diagram of a partial discharge test circuit of a high-voltage switch cabinet.
Detailed Description
The invention aims to provide a partial discharge identification method for a high-voltage switch cabinet;
fig. 1 is a schematic diagram of a partial discharge test circuit of a high-voltage switch cabinet, in which a module 1 for measuring frequency and phase of the voltage of the switch cabinet is connected with a square wave generating device 2; the phase and frequency output by the module 1 for measuring frequency and phase are used as trigger signals of the square wave generating device 2 to generate standard square waves with uniform frequency and phase; the transient ground voltage sensor 3 is fixed on the high-voltage switch cabinet, and the partial discharge measurement system 4 is connected with the transient ground voltage sensor 3 and is used for collecting partial discharge signals of the high-voltage switch cabinet in operation; the method adopts a form of superimposed square waves, and is mainly characterized in that a square wave signal and a high-voltage sinusoidal signal applied by the tested high-voltage switch cabinet have the same frequency and the same phase, so that when partial discharge is generated at the insulation weak position of the tested high-voltage switch cabinet, the partial discharge signal can be separated from other interference signals by phase information more effectively; therefore, partial discharge signals of the switch cabinet are collected through the transient ground voltage sensor, whether the signals are partial discharge signals or not is judged according to the characteristics of the tested signals, and the position of partial discharge is analyzed; the method specifically comprises the following steps:
step 1: under the condition of live operation of the switch cabinet, detecting signals by using a transient earth voltage sensor and a measuring system, and setting the maximum amplitude of the absolute value of the measured signals in the step 1 as Y;
step 2: acquiring the change condition of sinusoidal voltage of high-voltage electricity of the switch cabinet along with time, calculating the frequency f and the phase A of the sinusoidal voltage, shaping to generate square wave signals with the same frequency f (Hz) and the same phase A, wherein the high level of the square wave signals is 1-10V, and the low level of the square wave signals is 0;
and step 3: injecting the square wave signal to the ground on the shell of the switch cabinet, wherein the ground is the same as the ground of the output signal of the transient voltage sensor in the step 1;
and 4, step 4: detecting signals by using the same sensor and measuring system as in the step 1;
and 5: sampling the test signal obtained in the step (4), wherein the signal value of each time point after sampling is called as sampling data, and the total time length of sampling is not less than 10 seconds and is an integral multiple of the reciprocal of the frequency f of the sinusoidal voltage in the step (2);
step 6: dividing the total time of the sampling in the step 4 into n time segments with the length of 10 microseconds from the time point of starting timing of measurement, wherein the number of the time segments is n-1, 2 and 3 … … in sequence;
and 7: if the sampled data in each time period has an absolute value higher than Y/2, all the data in the time period is called a valid pulse, the time period number n corresponding to each valid pulse is recorded, if the n is larger than 100000/f, 100000/f is subtracted from n until n is smaller than 100000/f;
and 8: counting the number of all effective pulses in the total time length of the sampling in the step 4, and recording the number as N;
and step 9: according to the time section number n corresponding to the effective pulse in the step 7, counting the number of the effective pulses which are in accordance with a characteristic interval 10000/(18 x f) < n <20000/(9 x f), and recording the number as M;
step 10: if M/N is greater than 0.5, considering that partial discharge exists in the switch cabinet in the step 1, closely paying attention to the insulation condition or performing maintenance, if 0.3< M/N <0.5, considering that partial discharge possibly exists in the switch cabinet in the step 1, and intensively observing, if M/N <0.3, considering that partial discharge does not exist in the switch cabinet in the step 1, and ensuring that the insulation condition is safe;
the transient ground voltage sensor is a transient ground voltage (TEV) sensor based on a coupling capacitance principle;
the measuring system is a partial discharge tester or oscilloscope with the sampling frequency not lower than 20MHz, and the input impedance is not lower than 1 megaohm.
Claims (4)
1. A partial discharge identification method for a high-voltage switch cabinet; the method is characterized in that a module (1) for measuring the frequency and the phase of the voltage of the switch cabinet is connected with a square wave generating device (2); the transient ground voltage sensor (3) is fixed on the high-voltage switch cabinet, and the partial discharge measurement system (4) is connected with the transient ground voltage sensor (3); collecting partial discharge signals of the operating high-voltage switch cabinet; specifically, a superimposed square wave form is adopted, a partial discharge signal of the switch cabinet is acquired through a transient ground voltage sensor, whether the partial discharge signal is a discharge signal or not is judged according to the characteristics of the tested signal, and the position of partial discharge is analyzed; the method specifically comprises the following steps:
step 1: under the condition of live operation of the switch cabinet, detecting signals by using a transient earth voltage sensor and a local discharge measuring system, and setting the maximum amplitude of the absolute value of the detected signals as Y;
step 2: acquiring the change condition of sinusoidal voltage of high-voltage electricity of the switch cabinet along with time, calculating the frequency f and the phase A of the sinusoidal voltage, shaping to generate square wave signals with the same frequency f (Hz) and the same phase A, wherein the high level of the square wave signals is 1-10V, and the low level of the square wave signals is 0;
and step 3: injecting the square wave signal to the ground on the shell of the switch cabinet, wherein the ground is the same as the ground of the output signal of the transient voltage sensor in the step 1;
and 4, step 4: detecting signals by using the same sensor and measuring system as in the step 1;
and 5: sampling the test signal obtained in the step (4), wherein the signal value of each time point after sampling is called as sampling data, and the total time length of sampling is not less than 10 seconds and is an integral multiple of the reciprocal of the f in the step (2);
step 6: dividing the total time of the sampling in the step 4 into n time segments with the length of 10 microseconds from the time point of starting timing of measurement, wherein the number of the time segments is n-1, 2 and 3 … … in sequence;
and 7: sampling the amplitude of the absolute value of the measured signal in each time period, if the amplitude of one absolute value is higher than Y/2, then all data in the time period is called a valid pulse, recording the time period number n corresponding to each valid pulse, and if the n is larger than 100000/f, subtracting 100000/f from n until n is smaller than 100000/f; wherein 100000 is derived from the reciprocal of 10 microseconds;
and 8: counting the number of all effective pulses in the total time length of the sampling in the step 4, and recording the number as N;
and step 9: according to the time period number n corresponding to the effective pulse in the step 7, counting the number of the effective pulses which are in accordance with a characteristic interval 10000/(18 f) < n <20000/(9 f), and recording the number as M to represent the number of points of the effective pulses in the discharge characteristic phase;
step 10: if M/N >0.5, it is considered that partial discharge exists in the switch cabinet in the step 1, insulation condition should be closely paid attention or maintained, if 0.3< M/N <0.5, it is considered that partial discharge may exist in the switch cabinet in the step 1, observation should be strengthened, and if M/N <0.3, it is considered that partial discharge does not exist in the switch cabinet in the step 1, insulation condition is safe.
2. The partial discharge identification method for a high-voltage switchgear according to claim 1; the frequency and phase measuring module is characterized by being formed by sequentially connecting a shaping circuit, a counter circuit and an output part, wherein the shaping circuit is used for shaping a sine periodic signal into a square signal; the counter circuit obtains the zero crossing phase and the period of the signal through zero crossing timing and clock counting, and the zero crossing phase and the period are output by the output part.
3. The partial discharge identification method for a high-voltage switchgear according to claim 1; characterized in that the transient ground voltage sensor is a transient ground voltage (TEV) sensor based on the coupling capacitance principle.
4. The partial discharge identification method for a high-voltage switchgear according to claim 1; the partial discharge measurement system is characterized by being a partial discharge tester or oscilloscope with the sampling frequency not lower than 20MHz, and the input impedance is not lower than 1 megaohm.
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CN118444113A (en) * | 2024-07-08 | 2024-08-06 | 江西华莱电技术有限公司 | Partial discharge detection method of switch cabinet and high-voltage switch cabinet |
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