CN-115902612-B - Device and method for measuring voltage across break of DC breaker

CN115902612BCN 115902612 BCN115902612 BCN 115902612BCN-115902612-B

Abstract

The device comprises a follow current module, an energy discharging module, a bidirectional high-voltage pulse absorbing module and a voltage isolation sampling module, wherein the follow current module comprises a diode D1 and a diode D2 which are reversely connected in series to measure voltages in different directions generated by the two ends of a fracture of the direct current breaker under different working conditions, the energy discharging module comprises a resistor R1 and a resistor R2 which are connected in series, the bidirectional high-voltage pulse absorbing module comprises a capacitor C1 and a capacitor C2 which respectively absorb voltage shocks in different directions born by the two ends of the fracture of the direct current breaker, the energy discharging module and the follow current module are connected in parallel and then connected in series with the bidirectional high-voltage pulse absorbing module, the voltage isolation sampling module comprises a front-stage sampling resistor R5, a linear optocoupler and a rear-stage sampling resistor R6, and the front-stage sampling resistor R5 is connected with the front stage of the linear optocoupler, and the rear-stage sampling resistor R6 is connected with the rear stage of the linear optocoupler.

Inventors

HE HAILONG
WU YI
Yao Chaoyue
NIU CHUNPING
RONG MINGZHE

Assignees

西安交通大学

Dates

Publication Date: 20260512
Application Date: 20221123

Claims (7)

1. The device for measuring the voltage at two ends of a fracture of a direct current breaker is characterized by comprising a follow current module, an energy release module, a bidirectional high-voltage pulse absorption module, a multi-stage surge protection module and a voltage isolation sampling module, wherein, The follow current module comprises a diode D1 and a diode D2 which are connected in series in an opposite direction to measure voltages in different directions generated by two ends of a break of the direct current breaker under different working conditions; the energy release module comprises a resistor R1 and a resistor R2 which are connected in series; The bidirectional high-voltage pulse absorption module comprises a capacitor C1 and a capacitor C2 which absorb voltage shocks in different directions born by two ends of a fracture of the direct current breaker respectively, the energy discharging module and the follow current module are connected in parallel and then connected in series with the bidirectional high-voltage pulse absorption module, and a resistor R1 and a resistor R2 are respectively used as energy discharging resistors of the capacitor C1 and the capacitor C2; The multi-stage surge protection module includes, The first-stage surge protection module comprises a piezoresistor RV1, a piezoresistor RV2 and a gas discharge tube, wherein the piezoresistor RV1 and the piezoresistor RV2 are connected in series, one end of the gas discharge tube is connected to an equipotential connecting point of the piezoresistor RV1 and the piezoresistor RV2, and the other end of the gas discharge tube is grounded; the second-stage surge protection module comprises a safety capacitor C3 and a safety capacitor C4 which are connected in series, wherein an equipotential junction point of the safety capacitor C3 and the safety capacitor C4 is grounded; the third-stage surge protection module comprises transient voltage suppression diodes (TVS) connected in parallel at two ends of the second-stage surge protection module; The voltage isolation sampling module comprises a front-stage sampling resistor R5, a linear optocoupler and a rear-stage sampling resistor R6, the front-stage sampling resistor R5 is connected with the front stage of the linear optocoupler, the rear-stage sampling resistor R6 is connected with the rear stage of the linear optocoupler, a current-limiting resistor R3 and a current-limiting resistor R4 are respectively arranged between the bidirectional high-voltage pulse absorption module and a piezoresistor RV1 and between the bidirectional high-voltage pulse absorption module and the piezoresistor RV2, the resistor R1, the capacitor C1, the current-limiting resistor R3, the piezoresistor RV1, the piezoresistor RV2, the current-limiting resistor R4, the capacitor C2 and the resistor R2 are sequentially connected in series to form a loop, the front stage of the linear optocoupler collects arc voltage signals at two ends of a dynamic contact fracture of the direct current breaker in the switching-off process through the front-stage sampling resistor R5, photoelectric conversion is realized through the linear optocoupler, and voltage analog quantity on the front-stage sampling resistor R5 is transmitted to the rear-stage sampling resistor R6; and a diode D3 and a diode D4 for limiting the current flow direction in the circuit are further arranged between the first-stage surge protection module and the second-stage surge protection module.
2. The device for measuring the voltage across the break of a dc breaker according to claim 1, characterized in that the diode D3 is connected between a current limiting resistor R3 and a varistor RV1, and the diode D4 is connected between a current limiting resistor R4 and a varistor RV 2.
3. The device for measuring the voltage across the break of a dc breaker according to claim 1, characterized in that the current limiting resistor R3 and the current limiting resistor R4 have equal values and are not higher than the kiloohm level.
4. The device for measuring the voltage across the break of the direct current breaker according to claim 1, wherein the resistor R1 and the resistor R2 have values not lower than megaohm, and the capacitor C1 and the capacitor C2 have equal values and not lower than microfarad.
5. The device for measuring the voltage across the break of the direct current breaker according to claim 1, wherein the operating voltage threshold of the piezoresistors RV1, RV2 is kept uniform and higher than the operating voltage threshold of the gas discharge tube.
6. The device for measuring the voltage across the break of a dc breaker according to claim 1, characterized in that the safety capacitor C3 is identical to the safety capacitor C4.
7. The method for measuring a voltage across a break of a direct current breaker according to any one of claims 1-6, characterized in that it comprises the steps of, S1, connecting the device for measuring the voltage at two ends of a fracture of the direct current breaker to two ends of a moving contact and a fixed contact of the direct current breaker, wherein the fracture voltage is Uab; s2, when the direct current breaker is switched on, the break voltage Uab=0; S3, when the direct current breaker is opened; If the direct current breaker breaks forward current, the break voltage Uab >0, at the moment, the two ends of the break of the direct current breaker start from an arcing state, the break voltage Uab is arc voltage, the diode D1 bears reverse voltage to cut off, the diode D2 bears forward voltage to conduct, and as the arc voltage is smaller than the action voltage of each stage of surge protection module, the break voltage Uab signal reaches the front stage sampling resistor R5 through the capacitor C1, the current limiting resistor R3 and the diode D3, the linear optocoupler transmits the voltage signal on the front stage sampling resistor R5 to the rear stage sampling resistor R6 through photoelectric conversion, a fixed transmission ratio exists between the voltage values of the front stage sampling resistor and the rear stage sampling resistor, and the measurement of the arc voltage at the two ends of the break of the moving contact of the direct current breaker is realized through the measurement of the voltage value of the rear stage sampling resistor R6; When the direct current breaker extinguishes an arc, the voltage at two ends of a fracture is equal to the system voltage, the voltage is larger than the action voltage of each level of surge protection module, the voltage limiting resistor, the gas discharge tube and the transient voltage suppression diode TVS act step by step to limit the voltage, and finally the voltage of the rear end sampling resistor R6 is clamped in a bearing range, so that the linear optocoupler and the rear end measuring circuit are protected from being damaged by the system voltage; when the system voltage is reduced, the capacitor C1 releases stored energy through an energy release loop formed by the energy release resistor R1, the piezoresistor RV1 and the current limiting resistor R3, so as to prepare for the next measurement; If the direct current breaker is disconnected by reverse current, the break voltage Uab <0, the two ends of the break of the direct current breaker start from an arcing state, the diode D1 is conducted by forward voltage, the diode D2 is cut off by reverse voltage, and the break voltage Uab signal reaches the pre-stage sampling resistor R5 through the capacitor C2, the current limiting resistor R4 and the diode D4; When the direct current circuit breaker extinguishes an electric arc, the voltage dependent resistor, the gas discharge tube and the transient voltage suppression diode TVS act to limit the voltage step by step, and finally the voltage of the rear end sampling resistor R6 is clamped in a bearing range, so that the linear optocoupler and the rear end measuring circuit are protected from being damaged by high voltage; When the system voltage drops, the capacitor C2 releases stored energy through an energy release loop formed by the energy release resistor R2, the piezoresistor RV2 and the current limiting resistor R4, and the preparation is made for the next measurement.

Description

Device and method for measuring voltage across break of DC breaker Technical Field The invention belongs to the technical field of voltage measurement of switching equipment, and particularly relates to a device and a method for measuring voltages at two ends of a break of a direct current breaker. Background Extra-high voltage direct current transmission systems are attracting attention by virtue of their excellent performances in the aspects of renewable energy integration, capacity expansion of power systems, power grid stability improvement and the like. The direct current circuit breaker, in particular to a direct current circuit breaker with medium-high voltage level, is used as engineering backbone equipment in a direct current power system, is responsible for completing the operation mode switching and line fault clearing of the direct current power transmission system, and has great significance for guaranteeing the safe, economic and flexible operation of the direct current power system. Especially in the track traffic field, as an indispensable key protection device of the track traction direct current power supply system, along with the large-scale construction of the track traffic, the track traction direct current power supply system is more and more widely applied, and the demand for the medium-high voltage direct current circuit breaker with good breaking capability is also more and more large. The arc voltage is an important parameter capable of reflecting the arc extinguishing performance of the medium-high voltage direct current breaker to a great extent, and meanwhile, the arc voltage can also accurately reflect the action state of the moving and static contacts of the breaker in the opening process, which is beneficial to the design and research and development of many manual zero-crossing type high-voltage and high-capacity direct current breakers. Therefore, numerous researchers and engineering designers have been interested in its measurement for many years. However, in the current practical engineering application, because the system voltage level of the direct current breaker is higher, taking a medium-voltage direct current breaker and a high-voltage direct current breaker as examples, the system voltage is at least above kilovolts, and can even reach tens of kilovolts at the highest, and in view of the fact that once the breaker is in breaking operation, the two ends of the formed movable and static contact fracture bear corresponding system voltages, the voltage measurement at the two ends of the movable and static contact fracture obviously cannot adopt a common low-voltage measurement means, but if high-voltage measurement means such as a high-voltage probe are adopted, the accuracy of the result and the error are difficult to ensure for arc voltage measurement between the fractures formed in the breaking process of the movable and static contact of the breaker due to the fact that the measuring range of the high-voltage probe is large. The above information disclosed in the background section is only for enhancement of understanding of the background of the invention and therefore may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Disclosure of Invention Aiming at the problems existing in the prior art, the invention provides a device and a method for measuring the voltages at two ends of a breaker fracture of a direct current breaker, which overcome the defects and the shortcomings of the existing measuring device or measuring instrument, not only can accurately measure the arc voltage between the fracture formed by the moving and static contacts of the breaker in the breaking process, but also can bear the system voltage applied to the two ends of the fracture of the moving and static contacts after the breaker is broken, and protect a measuring circuit at the rear end from being damaged by the higher system voltage. The invention aims at realizing the following technical proposal, the device for measuring the voltage at two ends of the fracture of the direct current breaker comprises a follow current module, an energy release module, a bidirectional high-voltage pulse absorption module, a multi-stage surge protection module and a voltage isolation sampling module, wherein, The follow current module comprises a diode D1 and a diode D2 which are connected in series in an opposite direction to measure voltages in different directions generated by two ends of a break of the direct current breaker under different working conditions; the energy release module comprises a resistor R1 and a resistor R2 which are connected in series; The bidirectional high-voltage pulse absorption module comprises a capacitor C1 and a capacitor C2 which absorb voltage shocks in different directions born by two ends of a fracture of the direct current breaker respectively, the energy discharging module and the follow current modul