CN-122026885-A - Solid-state alternating current breaker based on thyristor zero-voltage on-off and control method thereof

CN122026885ACN 122026885 ACN122026885 ACN 122026885ACN-122026885-A

Abstract

The invention discloses a solid-state alternating current circuit breaker based on zero-voltage on-off of a thyristor and a control method thereof. The solid-state alternating current circuit breaker is formed by connecting a thyristor and a first quick mechanical switch in series, wherein the thyristor is connected with positive through current, the negative branch is formed by connecting at least one diode and a second quick mechanical switch in series, the diode is connected with negative through current, the thyristor breaks current, does not bear voltage, is turned on at zero voltage and turned off at zero voltage during operation, the diode bears current and voltage, the withstand voltage level is higher than Xiang Dianya peak value, the quick mechanical switch bears voltage, does not break current, the withstand voltage level is higher than phase voltage peak value, and is switched on and switched off at zero current during operation. According to the invention, the thyristors and the quick mechanical switch can be controlled according to the voltage and current polarity according to the specific time sequence, so that the voltage born by the two ends of the thyristors is far lower than the voltage born by the two ends of the diode, and when the voltage level of an alternating current system is increased, the number of the thyristors can still be kept unchanged, and the economical efficiency is improved.

Inventors

LU YI
NI XIAOJUN
LI ZIMING

Assignees

国网浙江省电力有限公司电力科学研究院

Dates

Publication Date: 20260512
Application Date: 20260410

Claims (10)

1. A solid-state alternating current breaker based on zero-voltage on-off of a thyristor is characterized by comprising a positive branch and a negative branch; the forward branch is formed by connecting a thyristor and a first rapid mechanical switch in series, and the thyristor is in forward through flow; The negative branch is formed by connecting at least one diode and a second rapid mechanical switch in series, and the diode flows in a negative direction; The thyristor breaks current, does not bear voltage, is turned on and turned off at zero voltage during operation, the diode bears current and voltage, the withstand voltage level is higher than Xiang Dianya peak values, the quick mechanical switch bears voltage, does not break current, the withstand voltage level is higher than phase voltage peak values, and zero current is switched on and zero current is switched off during operation.
2. The solid state ac circuit breaker based on thyristor zero voltage switching according to claim 1 wherein the thyristor, diode and fast mechanical switch all bear the same level of fault current, the thyristor blocks positive half-wave fault current and the diode blocks negative half-wave fault current.
3. The control method of a solid state ac circuit breaker according to claim 1 or 2, characterized in that the thyristor and the fast mechanical switch are controlled by a time sequence control strategy according to the voltage and current polarities; In the conducting process of the solid-state alternating current circuit breaker, firstly, enabling a second quick mechanical switch to complete switching-on in a positive voltage half-wave, enabling a first quick mechanical switch to complete switching-on in a negative voltage half-wave, and then enabling a thyristor to trigger conducting in a negative voltage half-wave; In the turn-off process of the solid-state alternating current circuit breaker, no matter the fault current occurs in a positive half wave or a negative half wave, time sequence control is started when the fault current is equal to the next current negative half wave, the thyristor is normally in zero-crossing triggering conduction before the fault current is equal to the next current negative half wave, the first quick mechanical switch and the second quick mechanical switch keep being switched on, when the next current negative half wave is reached, the first quick mechanical switch completes the switching off, meanwhile, a thyristor triggering signal is withdrawn, and then the second quick mechanical switch completes the switching off in the next voltage positive half wave.
4. A control method according to claim 3, characterized in that the voltage U of the parallel ports of the positive and negative branches near the power supply side is measured, the current I flowing in the positive direction into the solid state ac circuit breaker is measured, and the measured voltage and current are used for controlling the switching of the thyristor and the opening and closing of the fast mechanical switch.
5. The control method according to claim 4, wherein the switching-on time of the first and second mechanical switches is set to be T SW1_close and T SW2_close , respectively, the phase voltage rating peak value of the ac system is U peak , the ac system frequency is f, the switching-on voltages of the desired first and second mechanical switches are set to be U SW1_close 、U SW2_close , respectively, and the desired thyristor turn-on voltage is set to be U g1_on ; considering the delay caused by the action time of the quick mechanical switch, the actual closing command voltages of the first quick mechanical switch and the second quick mechanical switch are respectively U SW1_close_delay 、U SW2_close_delay , and the calculation formula is as follows: , In the conducting process of the solid-state alternating current circuit breaker, a second quick mechanical switch firstly sends a switching-on instruction when the voltage U=U SW2_close_delay , the second quick mechanical switch completes switching-on after the time of T SW2_close , the voltage U is required to be guaranteed to be 0at the moment, then the first quick mechanical switch sends a switching-on instruction when the voltage U=U SW1_close_delay , the first quick mechanical switch completes switching-on after the time of T SW1_close , the voltage U is required to be guaranteed to be 0at the moment, and finally a thyristor trigger pulse is given to conduct when the voltage U=U g1_on , and the voltage U is required to be guaranteed to be 0at the moment.
6. The control method according to claim 5, wherein, to realize that the thyristor always bears zero voltage during the conduction of the solid-state ac circuit breaker, various parameters of the time sequence control satisfy the following conditions: 。
7. The control method according to claim 4, wherein the opening time of the first and second mechanical switches is set to be T SW1_open and T SW2_open , respectively, the overcurrent protection threshold is I oc , when the current of the solid-state ac circuit breaker satisfies |i| > I oc , an overcurrent fault is considered to occur, the turn-off process of the solid-state ac circuit breaker is executed, the ac system frequency is f, the opening currents of the desired first and second mechanical switches are I SW1_open and I SW2_open , respectively, and the desired thyristor turn-off current is I g1_off ; Considering delay caused by the action time of the quick mechanical switch, the actual switching-off command currents of the first quick mechanical switch and the second quick mechanical switch are I SW1_open_delay 、I SW2_open_delay respectively, and the calculation formula is as follows: , In the turn-off process of the solid-state alternating current circuit breaker, the first quick mechanical switch firstly sends a turn-off instruction when the current I=I SW1_open_delay , the first quick mechanical switch finishes turn-off after the time of T SW1_open , the current I <0 is required to be ensured, then the thyristor is enabled to cancel the trigger pulse when the current I=I g1_off is required to be ensured, the current I <0 is required to be ensured, and finally the second quick mechanical switch sends a turn-off instruction when the current I=I SW2_open_delay , and the second quick mechanical switch finishes turn-off after the time of T SW2_open , the current I >0 is required to be ensured.
8. The control method according to claim 7, wherein to achieve that the thyristor is always subjected to zero voltage during the turn-off of the solid-state ac circuit breaker, the parameters related to the first fast mechanical switch SW1, the second fast mechanical switch SW2 and the thyristor g1 satisfy the following conditions: 。
9. The control method according to claim 8, wherein the values of I SW1_open 、I SW2_open and I g1_off are: 。
10. a control method according to claim 3, characterized in that as the supply voltage increases, the number of diodes needs to be increased to raise the withstand voltage level, and the number of thyristors remains unchanged.

Description

Solid-state alternating current breaker based on thyristor zero-voltage on-off and control method thereof Technical Field The invention belongs to the technical field of alternating current circuit breakers, and particularly relates to a solid alternating current circuit breaker based on zero-voltage on-off of a thyristor and a control method thereof. Background The traditional mechanical alternating current circuit breaker can generate electric arc when breaking fault current, and contact wear and equipment service life reduction are easy to cause. The solid-state alternating current breaker based on the fully-controlled semiconductor devices such as insulated gate bipolar transistors, metal oxide semiconductor field effect transistors and the like can realize arc-free breaking, and has the advantages of small volume and high breaking speed. However, since the through-current level of the fully controlled semiconductor device is limited, the breaking capacity of the solid-state ac circuit breaker is difficult to further improve. When the through-current level is raised by adopting a parallel connection mode of devices, the problems of dynamic current sharing, grid oscillation and the like are also faced. The adoption of the semi-controlled semiconductor device with the thyristor as the main part can obviously improve the breaking capacity of the solid-state alternating current breaker, and the through-flow level of the thyristor is obviously higher than that of the full-controlled semiconductor device. According to the semi-control characteristic of the thyristors, two thyristors are usually required to be connected in anti-parallel as a basic unit, and a plurality of basic units are connected in series by combining the system voltage level, so that the scheme can obviously increase the device consumption of the thyristors, and the economy of the solid-state alternating current circuit breaker is insufficient. Disclosure of Invention In order to solve the problems in the prior art, the invention provides a solid-state alternating current breaker based on zero-voltage switching of a thyristor and a control method thereof, which are used for reversely connecting the thyristor with a diode in parallel to construct an asymmetric solid-state alternating current breaker topology, and simultaneously designing a specific time sequence control strategy to realize zero-voltage switching of the thyristor, wherein when the voltage level of a system is increased, no requirement is placed on the withstand voltage level of the thyristor, and the number of the thyristors can be kept unchanged so as to remarkably improve the economical efficiency of the solid-state alternating current breaker. The invention adopts the following technical scheme. In a first aspect, the invention provides a solid-state alternating current circuit breaker based on thyristor zero voltage on-off, which comprises a positive branch and a negative branch; the forward branch is formed by connecting a thyristor and a first rapid mechanical switch in series, and the thyristor is in forward through flow; The negative branch is formed by connecting at least one diode and a second rapid mechanical switch in series, and the diode flows in a negative direction; The thyristor breaks current, does not bear voltage, is turned on and turned off at zero voltage during operation, the diode bears current and voltage, the withstand voltage level is higher than Xiang Dianya peak values, the quick mechanical switch bears voltage, does not break current, the withstand voltage level is higher than phase voltage peak values, and zero current is switched on and zero current is switched off during operation. Further, the thyristor, the diode and the fast mechanical switch all bear the same level of fault current, the thyristor blocks the positive half-wave fault current, and the diode blocks the negative half-wave fault current. In a second aspect, the present invention provides a control method of the solid-state ac circuit breaker, which uses a time sequence control strategy to control the thyristor and the fast mechanical switch according to the voltage and the current polarity, so that the voltage born by the two ends of the thyristor is far lower than the voltage born by the two ends of the diode; In the conducting process of the solid-state alternating current circuit breaker, firstly, enabling a second quick mechanical switch to complete switching-on in a positive voltage half-wave, enabling a first quick mechanical switch to complete switching-on in a negative voltage half-wave, and then enabling a thyristor to trigger conducting in a negative voltage half-wave; In the turn-off process of the solid-state alternating current circuit breaker, no matter the fault current occurs in a positive half wave or a negative half wave, time sequence control is started when the fault current is equal to the next current negative half wave, the thyristor is normally in zero-cr