CN-122000980-A - Online switching method and system for converter station of multi-terminal direct current transmission system

CN122000980ACN 122000980 ACN122000980 ACN 122000980ACN-122000980-A

Abstract

The invention belongs to the technical field of power electronics, and particularly relates to an online switching method and system for a converter station of a multi-terminal direct current transmission system. The online switching-in mode of the method comprises 1) confirming that a first converter station and a second converter station are respectively in constant voltage control and constant current control, controlling unlocking operation of the first converter station and the second converter station, wherein the first converter station and the second converter station are respectively an inversion station and a rectification station, 2) confirming that the next inversion station is in constant current control, delaying a certain time to send a command for switching on a direct-current line switch of the inversion station, controlling the inversion station to unlock operation under the condition that the time length of confirming that the switch is in a closed state is smaller than a first time length threshold value, 3) confirming that the next rectification station is in constant current control, delaying a certain time length to send a command for switching on the direct-current line switch of the rectification station, controlling unlocking operation of the rectification station under the condition that the time length of confirming that the switch is in a closed state is smaller than a second time length threshold value, and repeating steps 2-3) if the inversion station and the rectification station to be switched in exist.

Inventors

ZHANG WENBO
YU GUANGLIN
SHAO ZHUKE
BI YANHE
FAN CAIYUN
LIU KUN
HUANG YONGRUI
LIU LULU
LI KAI
HU QIULING
YUAN HONGTAO
LIU GUAN

Assignees

许继电气股份有限公司
中国电气装备集团有限公司

Dates

Publication Date: 20260508
Application Date: 20251231

Claims (10)

1. The online switching method of the converter station of the multi-terminal direct current transmission system is characterized by comprising the following steps of: 1) The method comprises the steps of confirming that a first converter station and a second converter station are respectively and correspondingly under the conditions of constant voltage control and constant current control, and controlling the unlocking operation of the first converter station and the second converter station; 2) Under the condition that the next inversion station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the inversion station, and under the condition that the time period of the switch of the inversion station in a switching-on state is less than a first time period threshold value, controlling the unlocking operation of the inversion station; 3) Under the condition that the next rectification station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the rectification station, and under the condition that the time period of the switch of the rectification station in a switching-on state is less than a second time period threshold value, controlling the unlocking operation of the rectification station; If there are also inverter stations and rectifier stations to be put into operation, repeating steps 2) -3).
2. The method for online switching of a converter station of a multi-terminal direct current transmission system according to claim 1, wherein the online switching mode comprises: a) Under the condition that the first converter station, the second converter station and other inverter stations and rectifier stations put into the direct current transmission system are unlocked and operated, locking signals are respectively issued to one inverter station and one rectifier station in the other inverter stations and the rectifier stations; b) After confirming that the corresponding inversion station and rectification station are in a locking state, delaying for a certain period of time to respectively send out instructions of opening the DC pole line switches of the inversion station and the rectification station; c) If the direct current polar line switches of the inversion station and the rectification station are in a brake-separating state, if the inversion station and the rectification station to be withdrawn still exist except the first converter station and the second converter station, delaying for a certain period of time, respectively issuing the brake-separating instruction of the direct current polar line switch of the next inversion station and the rectification station in the other inversion station and the rectification station; d) And under the condition that other inversion stations and rectifier station direct current polar line switches are in a switching-off state, delaying for a certain time, and respectively issuing a first converter station locking instruction and a second converter station locking instruction to finish online exit.
3. The method for on-line switching of a converter station of a multi-terminal direct current transmission system according to claim 1 or 2, wherein the step of confirming that the converter station is in a constant voltage control mode comprises the step of controlling to switch the control mode of the converter station if the converter station is not in the constant voltage control mode; The method of confirming that the converter station is in the constant current control mode includes controlling to switch the control mode of the converter station if the converter station is not in the constant current control mode.
4. The method for on-line switching of a converter station of a multi-terminal dc power transmission system according to claim 1 or 2, wherein the step of confirming that the duration of the switch of the inverter station in the on-state is less than a first time threshold value comprises: Judging whether the time length of the direct current polar line switch of the inversion station is smaller than a first time length threshold value or not, if yes, confirming that the time length of the direct current polar line switch of the inversion station is smaller than the first time length threshold value, if not, controlling the direct current polar line switch of the inversion station to be switched off and delaying for a certain time length, and then judging again and carrying out corresponding processing until confirming that the time length of the direct current polar line switch of the inversion station is smaller than the first time length threshold value; the method for confirming that the time length of the switch in the closing state of the rectifying station is smaller than the second time length threshold value comprises the following steps: Judging whether the time length of the direct current polar line switch of the rectifying station is smaller than a second time length threshold value or not, if yes, confirming that the time length of the direct current polar line switch of the rectifying station is smaller than the second time length threshold value, if not, controlling the direct current polar line switch of the rectifying station to be switched off and delaying for a certain time length, and then judging again and carrying out corresponding processing until confirming that the time length of the direct current polar line switch of the rectifying station is smaller than the second time length threshold value.
5. The method for on-line switching of a converter station of a multi-terminal dc power transmission system according to claim 2, wherein the means for confirming that the dc pole line switch of the inverter station or the rectifier station is in the off state comprises: Judging whether the direct current polar line switch of the inversion station or the rectification station is in a brake-off state, if so, confirming that the direct current polar line switch of the inversion station or the rectification station is in the brake-off state, if not, delaying for a certain period of time, correspondingly issuing a brake-off instruction of the direct current polar line switch of the inversion station or the rectification station, and then re-judging and correspondingly processing until confirming that the direct current polar line switch of the inversion station or the rectification station is in the brake-off state; the means for confirming that the inverter station or the rectifier station is in the locked state includes: Judging whether the inversion station or the rectification station is in a locking state, if so, confirming that the inversion station or the rectification station is in the locking state, otherwise, delaying for a certain period of time, correspondingly issuing a locking instruction of the inversion station or the rectification station, and then re-judging and correspondingly processing until confirming that the inversion station or the rectification station is in the locking state; The time delay time in the mode of confirming that the direct current polar line switch of the inversion station or the rectification station is in the opening state is smaller than the time delay time in the mode of confirming that the inversion station or the rectification station is in the locking state.
6. The on-line switching system of the converter station of the multi-terminal direct current transmission system comprises a processor, wherein executable program instructions are stored in the processor, and the on-line switching system is characterized in that the executable program instructions are used for being executed to realize the on-line switching method of the converter station of the multi-terminal direct current transmission system, and the on-line switching mode in the method specifically comprises the following steps: 1) The method comprises the steps of confirming that a first converter station and a second converter station are respectively and correspondingly under the conditions of constant voltage control and constant current control, and controlling the unlocking operation of the first converter station and the second converter station; 2) Under the condition that the next inversion station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the inversion station, and under the condition that the time period of the switch of the inversion station in a switching-on state is less than a first time period threshold value, controlling the unlocking operation of the inversion station; 3) Under the condition that the next rectification station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the rectification station, and under the condition that the time period of the switch of the rectification station in a switching-on state is less than a second time period threshold value, controlling the unlocking operation of the rectification station; If there are also inverter stations and rectifier stations to be put into operation, repeating steps 2) -3).
7. The online switching system of a converter station of a multi-terminal direct current transmission system according to claim 6, wherein the online exiting mode in the method specifically comprises: a) Under the condition that the first converter station, the second converter station and other inverter stations and rectifier stations put into the direct current transmission system are unlocked and operated, locking signals are respectively issued to one inverter station and one rectifier station in the other inverter stations and the rectifier stations; b) After confirming that the corresponding inversion station and rectification station are in a locking state, delaying for a certain period of time to respectively send out instructions of opening the DC pole line switches of the inversion station and the rectification station; c) If the direct current polar line switches of the inversion station and the rectification station are in a brake-separating state, if the inversion station and the rectification station to be withdrawn still exist except the first converter station and the second converter station, delaying for a certain period of time, respectively issuing the brake-separating instruction of the direct current polar line switch of the next inversion station and the rectification station in the other inversion station and the rectification station; d) And under the condition that other inversion stations and rectifier station direct current polar line switches are in a switching-off state, delaying for a certain time, and respectively issuing a first converter station locking instruction and a second converter station locking instruction to finish online exit.
8. The on-line switching system of a converter station of a multi-terminal direct current transmission system according to claim 6 or 7, wherein the means for confirming that the converter station is in constant voltage control comprises means for controlling switching of the control means of the converter station if the converter station is not in constant voltage control; The method of confirming that the converter station is in the constant current control mode includes controlling to switch the control mode of the converter station if the converter station is not in the constant current control mode.
9. The system of claim 6 or 7, wherein the means for confirming that the switch of the inverter is in the on-state for a time period less than a first time period threshold comprises: Judging whether the time length of the direct current polar line switch of the inversion station is smaller than a first time length threshold value or not, if yes, confirming that the time length of the direct current polar line switch of the inversion station is smaller than the first time length threshold value, if not, controlling the direct current polar line switch of the inversion station to be switched off and delaying for a certain time length, and then judging again and carrying out corresponding processing until confirming that the time length of the direct current polar line switch of the inversion station is smaller than the first time length threshold value; the method for confirming that the time length of the switch in the closing state of the rectifying station is smaller than the second time length threshold value comprises the following steps: Judging whether the time length of the direct current polar line switch of the rectifying station is smaller than a second time length threshold value or not, if yes, confirming that the time length of the direct current polar line switch of the rectifying station is smaller than the second time length threshold value, if not, controlling the direct current polar line switch of the rectifying station to be switched off and delaying for a certain time length, and then judging again and carrying out corresponding processing until confirming that the time length of the direct current polar line switch of the rectifying station is smaller than the second time length threshold value.
10. The on-line switching system of a multi-terminal dc power transmission system according to claim 7, wherein the means for confirming that the dc pole line switch of the inverter or rectifier is in the off state comprises: Judging whether the direct current polar line switch of the inversion station or the rectification station is in a brake-off state, if so, confirming that the direct current polar line switch of the inversion station or the rectification station is in the brake-off state, if not, delaying for a certain period of time, correspondingly issuing a brake-off instruction of the direct current polar line switch of the inversion station or the rectification station, and then re-judging and correspondingly processing until confirming that the direct current polar line switch of the inversion station or the rectification station is in the brake-off state; the means for confirming that the inverter station or the rectifier station is in the locked state includes: Judging whether the inversion station or the rectification station is in a locking state, if so, confirming that the inversion station or the rectification station is in the locking state, otherwise, delaying for a certain period of time, correspondingly issuing a locking instruction of the inversion station or the rectification station, and then re-judging and correspondingly processing until confirming that the inversion station or the rectification station is in the locking state; The time delay time in the mode of confirming that the direct current polar line switch of the inversion station or the rectification station is in the opening state is smaller than the time delay time in the mode of confirming that the inversion station or the rectification station is in the locking state.

Description

Online switching method and system for converter station of multi-terminal direct current transmission system Technical Field The invention belongs to the technical field of power electronics, and particularly relates to an online switching method and system for a converter station of a multi-terminal direct current transmission system. Background The multi-terminal conventional direct current transmission system (such as a four-terminal conventional direct current transmission system) comprises a plurality of converter stations, wherein each converter station adopts a parallel operation mode, larger impulse voltage is usually generated in the switching process of the converter stations, and the bias voltage easily appears in the converter valves of the converter stations in the switching process, so that the risk of damage to the action of a valve arrester is caused. The invention patent of China with the application publication number of CN106549408A discloses an on-line input method of a multi-terminal high-voltage direct-current power transmission system current converter, wherein one end current converter at an inversion side is input into operation in a constant direct-current voltage control mode, and other end current converters at the inversion side are input into operation in a constant current control mode, so that stable on-line combination of the current converters is realized, and stable operation of other current converters is not interfered. Meanwhile, the method can realize accurate control of the transmission power of the current converter, and is convenient for departments such as scheduling to realize control of the transmission power of the current converter. Disclosure of Invention The invention aims to provide an online switching method and system for a converter station of a multi-terminal direct current transmission system, which are used for solving the problems that in the prior art, the impact voltage is large in the switching process of the converter station of the multi-terminal conventional direct current transmission system, and a converter valve is easy to generate bias voltage. In order to achieve the above purpose, the present invention provides an online switching method for a converter station of a multi-terminal direct current power transmission system, wherein the online switching method includes: 1) The method comprises the steps of confirming that a first converter station and a second converter station are respectively and correspondingly under the conditions of constant voltage control and constant current control, and controlling the unlocking operation of the first converter station and the second converter station; 2) Under the condition that the next inversion station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the inversion station, and under the condition that the time period of the switch of the inversion station in a switching-on state is less than a first time period threshold value, controlling the unlocking operation of the inversion station; 3) Under the condition that the next rectification station to be put into is under constant current control, delaying a certain time period to issue a command for switching on a direct current polar line switch of the rectification station, and under the condition that the time period of the switch of the rectification station in a switching-on state is less than a second time period threshold value, controlling the unlocking operation of the rectification station; If there are also inverter stations and rectifier stations to be put into operation, repeating steps 2) -3). Further, the online exit mode includes: a) Under the condition that the first converter station, the second converter station and other inverter stations and rectifier stations put into the direct current transmission system are unlocked and operated, locking signals are respectively issued to one inverter station and one rectifier station in the other inverter stations and the rectifier stations; b) After confirming that the corresponding inversion station and rectification station are in a locking state, delaying for a certain period of time to respectively send out instructions of opening the DC pole line switches of the inversion station and the rectification station; c) If the direct current polar line switches of the inversion station and the rectification station are in a brake-separating state, if the inversion station and the rectification station to be withdrawn still exist except the first converter station and the second converter station, delaying for a certain period of time, respectively issuing the brake-separating instruction of the direct current polar line switch of the next inversion station and the rectification station in the other inversion station and the rectification station; d) And under the condition that other