Test evaluation method and system for switching equipment with capacitive current frequently switched on and switched off
Technical Field
The invention relates to the field of electrical equipment tests, in particular to a test evaluation method and a test evaluation system for switch equipment with capacitive current being frequently switched on and switched off.
Background
In the process of developing a circuit breaker and other switching equipment, the capacitive current switching capacity is an important factor influencing the structure of an arc extinguish chamber and the switching-on/switching-off speed. The ultra-high voltage power grid has large power adjustment amplitude, and the capacity of an alternating current filter bank or a reactive compensation capacitor bank is large and the switching is frequent. When the switching equipment is used for switching on and off a capacitor bank or an alternating current filter bank, the switching-on inrush current is large, and although the capacitive current value is not large in the switching-on and switching-off process, the recovery voltage of the current is high when the current is switched on and off, and heavy breakdown is easy to occur, so that serious overvoltage is caused, and great damage is caused to a system. Theoretically, the operating conditions of the switching devices for switched capacitor banks (which can be considered uniformly for capacitor banks because the ac filter is mainly composed of capacitors) have the following characteristics:
(1) the capacitor bank to be put into use can be charged by the capacitor bank to generate inrush current with high amplitude and frequency, the inrush current amplitude is several times to dozens of times larger than normal working current, the frequency can reach thousands of hertz, and the contact fusion welding and burning loss, part damage, insulation damage and the like are easily caused.
(2) When the capacitive current is switched off, the recovery voltage is high, the duration is long, heavy breakdown is easy to occur, overvoltage is generated, and the serious threat is formed to the filter bank, the reactive power compensation device and system insulation.
(3) The capacitor bank is switched frequently, and the requirement on the electrical service life of the switch equipment is high.
Due to the above characteristics caused by the operating conditions, the contacts of the switching devices for switching the filter banks or the capacitor banks must have a higher electrical life and an extremely low re-breakdown probability.
Taking the operation condition of the filter bank circuit breaker in operation in the current direct current project as an example, the maximum operation times of a single-phase year can be close to 500 times. Considering the average service life of the circuit breaker, the circuit breaker actually used in engineering needs to be reliably opened and closed for 2500-3000 times or more at least, and if the circuit breaker is reliably opened and closed for 10 years without maintenance, the time of the circuit breaker needs to reach 5000 times. In the capacitor bank switching test specified by IEC and national standard, even the C2 test (which indicates that the test sample has extremely low heavy breakdown probability) only requires 120 times of switching inrush current tests and 168 times of switching-off tests, and it is difficult to verify whether the requirements of frequent operation in operation can be met.
Disclosure of Invention
In order to solve the problem that the conventional test evaluation method in the background art is difficult to verify whether the switch equipment can meet the requirement of frequent operation in operation, the invention provides a test evaluation method and a test evaluation system for the switch equipment which frequently opens and closes capacitive current; the method and the system provide an equivalent theoretical method of opening and closing test times in a C2-level test and operation conditions, a standard C2-level test in a type test is taken as reference, a C2-level margin test is designed to verify the safe operation performance of the switch equipment by combining the operation times required by field operation, and the test evaluation method of the switch equipment with frequent opening and closing capacitive current comprises the following steps:
step 1, performing a C2 standard test on switch equipment;
step 2, calculating the ratio of the accumulated arc energy of the switching equipment in the A-time closing pre-breakdown process in the C2-level standard test to the single closing average arc energy in the actual operation working condition as M;
step 3, calculating the number of times of short-arc breaking under reliable breaking of the switch equipment in an actual operation working condition corresponding to the condition that the switch equipment is broken for B times in a C2-level standard test and no heavy breakdown occurs as N;
step 4, carrying out X continuous cycle margin tests on the switch equipment, wherein each margin test comprises A times of closing and B times of short-burning arc breaking; the X is an upward integral value minus 1 of the ratio of the reliable opening and closing times required by the actual operation working condition to the reliable opening and closing times met by one C2 standard test simulation; the reliable opening and closing times met by the one-time C2-level standard test simulation are the smaller value of M and N;
step 5, if the switch equipment is reliably switched on and off, judging the reliable switching times of the switch equipment meeting the requirements of actual operation conditions;
wherein A, B, X, M and N are both positive integers;
further, the accumulated arc energy Qs in the A-time closing pre-breakdown process of the switch device in a C2 standard test is
Wherein ICMtThe maximum value of the switching-on inrush current of the switching equipment is obtained; t ismaxα is constant and 1 < α < 2;
further, the average arc energy Qa in the single turn-off pre-breakdown process in the actual operating condition is:
Tmaxthe maximum pre-breakdown time, α is constant and 1 & lt α & lt 2, ICMyThe maximum value of the high-frequency inrush current of the switching equipment under the operation working condition is obtained;
further, under the power frequency voltage, if the switching equipment is not subjected to heavy breakdown due to the fact that B times of short-time arcing is cut off in a C2 level standard test, the reliable cut-off times N of the switching equipment in the actual operation working condition is 10 × B;
furthermore, a closing resistance module is additionally arranged in the circuit breaker in the C2 standard test so as to prolong the service life of the contact of the switching equipment; the switching-on resistance module comprises a switching-on resistance and a resistance fracture;
further, the resistor fracture is connected in series with the main fracture of the switching device, and the closing resistor is connected in parallel with the resistor fracture; when the switch equipment is closed, the main fracture of the switch equipment is closed firstly, and then the resistor fracture is closed; when the switch equipment is switched off, only the main fracture of the switch equipment needs to be switched off;
further, the resistor fracture is connected in series with the closing resistor and is connected in parallel with the main fracture of the switching device; when the switch equipment is closed, the resistor fracture is closed firstly, and then the main fracture of the switch equipment is closed; when the switch equipment is switched off, only the main fracture of the switch equipment needs to be switched off;
the test evaluation system for the switch equipment which opens and closes the capacitive current frequently comprises:
the C2-level standard test unit is used for performing C2-level standard test on the switch equipment to be evaluated and outputting test data to the first calculation unit and the second calculation unit;
the first calculating unit is used for calculating accumulated arc energy of the switching equipment in the A closing pre-breakdown process in the C2 standard test and average arc energy of the single closing in the actual operating condition according to test data received from the C2 standard test unit; outputting the ratio M of the accumulated arc energy of the switching equipment in the A-time closing pre-breakdown process in the C2-level standard test to the single closing average arc energy in the actual operation working condition to a margin test unit;
the second calculating unit is used for calculating the reliable on-off times N of the switch equipment in the actual operation working condition corresponding to the condition that the switch equipment is not subjected to re-breakdown due to the B-time short arc on-off output by the C2-level standard test unit; the second calculating unit is used for outputting the times N to the margin testing unit;
the margin test unit is used for carrying out continuous X-cycle margin tests on the switch equipment to be evaluated, and each margin test comprises A times of closing and B times of short-arc switching-off; the margin test unit is used for selecting the smaller value of the parameter M output by the first calculation unit and the parameter N output by the second calculation unit as the reliable opening and closing times met by one-time C2-level standard test simulation; determining the cycle times X of the margin test according to the ratio of the reliable opening and closing times required by the actual operation working condition to the reliable opening and closing times met by one C2-level standard test simulation;
further, the test data received by the first calculating unit from the standard test unit of class C2 includes the maximum value of the switching equipment on-off inrush current and the maximum pre-breakdown time; the first calculation unit is used for receiving the maximum value of high-frequency inrush current of the switching equipment input by a user under the operating condition and a reference constant set after considering electric quantity loss;
further, the system operates under the power frequency voltage, and if the B times of short-time arcing cut-off in the C2-grade standard test unit do not cause heavy breakdown, the reliable cut-off times N of the switch equipment in the actual operation working condition is 10 × B;
further, the C2-level standard test unit comprises a closing resistor module, the closing resistor module comprises a closing resistor and a resistor fracture, and the closing resistor module is used for prolonging the service life of the contact of the switching equipment;
further, the resistor fracture is connected in series with the main fracture of the switching device, and the closing resistor is connected in parallel with the resistor fracture; when the C2-level standard test unit closes the switching equipment, the main fracture of the switching equipment is closed firstly, and then the resistor fracture is closed; when the C2-level standard test unit switches on or off the switch equipment, only the main fracture of the switch equipment needs to be switched on or off;
further, the resistor fracture is connected in series with the closing resistor and is connected in parallel with the main fracture of the switching device; when the C2-level standard test unit closes the switching equipment, closing the resistor fracture and then closing the main fracture of the switching equipment; when the C2 standard test unit switches on the switch equipment, only the main fracture of the switch equipment needs to be switched on and off.
The invention has the beneficial effects that: the technical scheme of the invention provides a test evaluation method and a test evaluation system for a switch device which frequently opens and closes capacitive current, wherein the method and the system provide an equivalent theoretical method under opening and closing test times and operation conditions in a C2-level test, and a C2-level margin test is designed to verify the safe operation performance of the switch device by taking a standard C2-level test in a type test as reference and combining operation times required by field operation; the method and the system can verify whether the switching equipment can meet the requirement of frequent switching operation in operation, evaluate the performance level of the capacitor bank frequently switched on and switched off by the switching equipment, provide reference for field maintenance and meet the requirement of long-term safe operation of the switching equipment in engineering.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
fig. 1 is a flowchart of a test evaluation method of a switchgear that frequently opens and closes a capacitive current according to an embodiment of the present invention;
fig. 2 is a block diagram of a test evaluation system of a switchgear that frequently opens and closes a capacitive current according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flowchart of a test evaluation method of a switchgear that frequently opens and closes a capacitive current according to an embodiment of the present invention; the method provides an equivalent theoretical method of opening and closing test times in a C2-level test and an operation condition, a standard C2-level test in a type test is taken as a reference, a C2-level margin test is designed to verify the safe operation performance of the switch equipment by combining the operation times required by field operation, and the test evaluation method of the switch equipment with frequent opening and closing of the capacitive current comprises the following steps:
step 101, performing a C2 standard test on the switch equipment;
102, calculating the ratio of the accumulated arc energy of the switching equipment in the A-time closing pre-breakdown process in the C2-level standard test to the single closing average arc energy in the actual operation working condition to be M;
further, the switch device has the accumulated arc energy Qs of A times of closing in a C2 standard test
Wherein ICMtThe maximum value of the switching inrush current of the switching equipment in the test is obtained; t ismaxα is constant and 1 < α < 2;
further, the single closing average arc energy Qa in the actual operating condition is:
wherein ICMyThe maximum value of the high-frequency inrush current of the switching equipment under the operation working condition is obtained; t ismaxα is constant and 1 < α < 2;
step 3, calculating the reliable on-off times of the switch equipment in the actual operation working condition corresponding to the condition that the switch equipment is subjected to B times of short arcing on-off in the C2-level standard test and the switch equipment is not subjected to re-breakdown as N;
further, under the power frequency voltage, if the short-time arcing is cut off for B times in a C2 level standard test and no heavy breakdown occurs, the reliable cut-off times N of the switch equipment in the actual operation working condition is 10 × B;
step 4, carrying out X continuous cycle margin tests on the switch equipment, wherein each margin test comprises A times of closing and B times of short-burning arc breaking; the X is an upward integral value minus 1 of the ratio of the reliable opening and closing times required by the actual operation working condition to the reliable opening and closing times met by one C2 standard test simulation; the reliable opening and closing times met by the one-time C2-level standard test simulation are the smaller value of M and N;
step 5, if the switch equipment is reliably switched on and off, judging the reliable switching times of the switch equipment meeting the requirements of actual operation conditions;
wherein A, B, X, M and N are both positive integers;
furthermore, a closing resistance module is additionally arranged in the circuit breaker in the C2 standard test so as to prolong the service life of the contact of the switching equipment; the switching-on resistance module comprises a switching-on resistance and a resistance fracture;
further, the resistor fracture is connected in series with the main fracture of the switching device, and the closing resistor is connected in parallel with the resistor fracture; when the switch equipment is closed, the main fracture of the switch equipment is closed firstly, and then the resistor fracture is closed; when the switch equipment is switched off, only the main fracture of the switch equipment needs to be switched off;
further, the resistor fracture is connected in series with the closing resistor and is connected in parallel with the main fracture of the switching device; when the switch equipment is closed, the resistor fracture is closed firstly, and then the main fracture of the switch equipment is closed; when the switch equipment is switched off, only the main fracture of the switch equipment needs to be switched off;
in the embodiment, a C2-grade standard test is carried out on the switching equipment under the power frequency voltage (50HZ), the switching equipment is closed 120 times in a C2-grade standard test, and the switching equipment is closed 120 times in a C2-grade standard test to accumulate arc energy
Average arc energy of single closure in actual operation condition
α is a constant, α value considers the power loss, α value is equal to 2 in the calculation without power loss, 1 is more than α is less than 2 in the method, and α is 1.8 in the embodiment;
taking the parameters of a 1100kV alternating current filter group circuit breaker in the current extra-high voltage direct current project as an example, the maximum value of inrush current of the circuit breaker with a closing resistor (1150 omega) is 5.3 kA;
when the high-frequency inrush current of the laboratory is considered as 5.3kA recently in the operation of the circuit breaker, Qs/Qa is approximately equal to 957; therefore, from the perspective of ablation resistance of the contact, the closing capacity of 120 times in the C2 level test can meet the closing capacity of 957 times (about 1000 times) in the current engineering operation;
further, when the laboratory performed the standard C2-grade test, 12 short arc breakings in BC1 and 84 short arc breakings in BC2 were collectively performed for a total of 96 short arc breakings. In operation, the opening phase is random, typically the shortest arcing time is 1ms or less, and the probability of a short arcing opening occurring within one half-wave (10ms) is about 1/10. If 96 times of short-arc breaking tests are carried out in the C2 level test set to reliably break, the probability of re-breakdown occurring in 960 times of breaking is extremely low in operation and approximately reaches 1000 times.
Fig. 2 is a block diagram of a test evaluation system of a switchgear that frequently opens and closes a capacitive current according to an embodiment of the present invention. A test evaluation system for a switchgear with frequent switching of capacitive current is shown, comprising:
the C2-level standard test unit 201 is used for performing C2-level standard test on the switch equipment to be evaluated, and outputting test data to the first calculation unit 202 and the second calculation unit 203;
a first calculating unit 202, wherein the first calculating unit 202 is used for calculating accumulated arc energy of the switching equipment in the A closing pre-breakdown process in the C2 standard test and average arc energy of single closing in the actual operating condition according to the test data received from the C2 standard test unit 201; outputting the ratio M of the total arc energy generated by the switching equipment in the C2-level standard test for A times to the arc energy generated by the switching equipment in the actual operation condition for a single time to the margin test unit 204;
the second calculating unit 203 is used for calculating the reliable on-off times N of the switching equipment in the actual operation working condition corresponding to the condition that the B-time short arc output by the C2-level standard testing unit 201 is not subjected to re-breakdown; the second calculating unit 203 is configured to output the number N to the margin testing unit 204;
a margin test unit 204, wherein the margin test unit 204 is used for carrying out continuous X-cycle margin tests on the switch equipment to be evaluated, and each margin test comprises A times of closing and B times of short-arc switching-on and switching-off; the margin test unit 204 is configured to select a smaller value of the parameter M output by the first calculating unit 202 and the parameter N output by the second calculating unit 203 as the number of reliable opening and closing times that is met by one-time C2-level standard test simulation; determining the cycle times X of the margin test according to the ratio of the reliable opening and closing times required by the actual operation working condition to the reliable opening and closing times met by one C2-level standard test simulation;
further, the test data received by the first calculating unit 202 from the standard test unit 201 in class C2 includes the maximum value of the switching equipment switching inrush current and the maximum pre-breakdown time; the first calculating unit 202 is configured to receive a maximum value of the high-frequency inrush current of the switching device under the operating condition and a reference constant set in consideration of power consumption, which are input by a user;
further, the system operates under the power frequency voltage, and if the B-time short-arc switching-off does not occur in the C2-level standard test unit 201, the reliable switching-off times N of the switching device in the actual operation condition is 10 × B;
further, the C2-level standard test unit 201 includes a closing resistor module, where the closing resistor module includes a closing resistor and a resistor break, and the closing resistor module is used to improve the service life of the switchgear contact;
further, the resistor fracture is connected in series with the main fracture of the switching device, and the closing resistor is connected in parallel with the resistor fracture; when the C2-level standard test unit 201 closes the switching device, the main fracture of the switching device is closed first, and then the resistor fracture is closed; when the C2-level standard test unit 201 switches on or off the switchgear, only the main fracture of the switchgear needs to be switched on or off;
further, the resistor fracture is connected in series with the closing resistor and is connected in parallel with the main fracture of the switching device; when the C2-level standard test unit 201 closes the switching device, the resistor fracture is closed and then the main fracture of the switching device is closed; when the C2 standard test unit 201 opens the switchgear, only the main break of the switchgear needs to be opened.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.