CN114498601A - Method for quickly putting third station of parallel three-terminal direct-current transmission system into operation - Google Patents
Method for quickly putting third station of parallel three-terminal direct-current transmission system into operation Download PDFInfo
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- CN114498601A CN114498601A CN202011269828.9A CN202011269828A CN114498601A CN 114498601 A CN114498601 A CN 114498601A CN 202011269828 A CN202011269828 A CN 202011269828A CN 114498601 A CN114498601 A CN 114498601A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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Abstract
The invention relates to a method for quickly switching in a third station of a parallel three-terminal direct-current transmission system, which comprises the steps of closing isolating switches at two sides of a high-speed parallel switch (HSS) of the third station after receiving a third station switching-in command; performing phase shift on the rectifying station, and simultaneously reducing the direct-current voltage reference value and the trigger angle limit value of the inverter station; after the direct-current voltages of the rectifier station and the inverter station are lower than a set threshold value, a high-speed parallel switch HSS of a third station is closed; and restarting the rectifying station and the inverter station, canceling the phase shift signal of the rectifying station, and recovering the direct-current voltage reference value and the trigger angle limit value of the inverter station. The invention increases the treatment to the inversion side and can quickly reduce the voltage of the direct current line. The method is suitable for a multi-terminal direct current transmission system, reduces the impact on primary equipment such as HSS switches and the like when the converter station is put into operation, and can reduce the current break time of a direct current system when the converter station is put into operation so as to reduce the influence on an alternating current system.
Description
Technical Field
The invention relates to the technical field of direct-current transmission methods, in particular to a method for quickly putting a third station of a parallel three-terminal direct-current transmission system into operation.
Background
The parallel three-terminal direct-current transmission system is formed by three converter stations in a parallel mode and is characterized in that the three converter stations share a direct-current bus. The parallel three-terminal direct-current power transmission system can operate at two ends and three ends, and can also realize the on-line conversion from two ends to three ends or from three ends to two ends, namely the on-line switching of the converter station. When a third station is brought online, the dc line voltage needs to be reduced quickly in order to reduce the impact on the primary equipment while reducing the disturbance of the dc system.
The method for rapidly reducing the voltage of the direct current line by the direct current power transmission system at two ends comprises the following steps: and (4) phase shifting at the rectifying side, namely shifting the trigger angle to 120 degrees, delaying for 50ms and then shifting the trigger angle to 160 degrees after the direct current is less than 0.05 pu.
In a parallel three-terminal direct-current power transmission system, when a third station is put into a third station on line, in order to reduce the impact on primary equipment, a method of reducing the voltage of a direct-current line to a fixed value and then switching on an HSS switch is needed, and in order to reduce the influence on the direct-current system, the voltage of the direct-current line needs to be reduced rapidly. The speed of the voltage drop of the direct current line is slow, and if the voltage of the direct current line is required to be lower than 0.2pu, the time is about 1800 ms.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for quickly switching in a third station of a parallel three-terminal direct-current power transmission system.
In order to achieve the aim, the invention provides a method for quickly putting a third station of a parallel three-terminal direct-current transmission system into service, which comprises the following steps:
after receiving a third station input command, closing the isolation knives on two sides of the high-speed parallel switch HSS of the third station;
performing phase shift on the rectifying station, and simultaneously reducing the direct-current voltage reference value and the trigger angle limit value of the inverter station;
after the direct-current voltages of the rectifier station and the inverter station are lower than a set threshold value, a high-speed parallel switch HSS of a third station is closed; and restarting the rectifying station and the inverter station, canceling the phase shift signal of the rectifying station, and recovering the direct-current voltage reference value and the trigger angle limit value of the inverter station.
Further, the performing of the commutation station phase shift comprises: and shifting the trigger angle of the rectifying station to 120 degrees, and delaying for 50ms to shift the trigger angle to 160 degrees after the direct current of the rectifying station is less than 0.05 pu.
Further, reducing the inverter station DC voltage reference value comprises reducing the inverter station DC voltage reference value from 1pu to 0-0.5 pu.
Further, reducing the dc voltage reference of the inverter station comprises: and sending a voltage regulating instruction to the inverter station voltage controller, and reducing the direct-current voltage reference value of the inverter station from 1pu to 0 pu.
Further, the reducing the triggering angle limit of the inverter station comprises: and sending a phase modulation instruction to the inverter station voltage controller, and reducing the trigger angle limit value of the inverter station to 105-110 degrees.
Further, the high-speed parallel switch HSS of the third station is closed after the direct-current voltage of the rectifying station and the direct-current voltage of the inverter station are lower than 0.6 pu.
Further, if the direct-current voltage of the rectifying station and the direct-current voltage of the inverter station are not lower than 0.6pu within the set time, the switching fails, the high-speed parallel switch HSS of the third station is not closed, and the isolating knives on two sides of the high-speed parallel switch HSS of the third station are disconnected.
The technical scheme of the invention has the following beneficial technical effects:
(1) in the prior art, only the rectification side is subjected to forced phase shift treatment, and the inversion side is only subjected to passive regulation. According to the technical scheme of the invention, on the basis of the prior technical scheme, the treatment on the inversion side is added, and the voltage of a direct current line can be quickly reduced. The method is suitable for a multi-terminal direct current transmission system, reduces the impact on primary equipment such as HSS switches and the like when the converter station is put into operation, and can reduce the current break time of a direct current system when the converter station is put into operation so as to reduce the influence on an alternating current system.
(2) In order to quickly reduce the voltage of the direct current line, the invention adopts the forced phase shift of the rectifying side, the inverter side quickly reduces the reference value of the direct current voltage to a new fixed value, and reduces the limit value of the trigger angle of the inverter side, so that the output direct current voltage is quickly reduced, and the input speed of the third station is greatly improved.
Drawings
Fig. 1 is a block diagram of a parallel three-terminal dc power transmission system;
FIG. 2 is a flow chart of the third station putting steps of the parallel connection of three terminals.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The parallel three-terminal direct-current transmission system consists of three converter stations and two sections of direct-current transmission lines, a single-pole system of the system is shown in figure 1, three high-speed parallel switches (HSS1, HSS2 and HSS3) are arranged at a station B and are respectively connected with the three converter stations, and the system is simultaneously used for isolating a fault area when a certain converter station or a certain section of line has a fault so as to ensure that the other two converter stations can normally operate.
When a third station of the parallel three-terminal direct-current power transmission system is switched in on line, the isolating switches on two sides of the HSS switch (high-speed parallel switch) are firstly closed, then the voltage of a direct-current line for operating the two stations is reduced, when the voltage of the direct-current line is smaller than a fixed value, the HSS switch corresponding to the station to be switched in is closed, then the two stations in original operation are restarted, the switched third station is unlocked, and the flow is shown in figure 2.
The third station is put into concrete implementation steps as follows:
1) after receiving a third station input command, closing the isolation knives on two sides of the high-speed parallel switch HSS of the third station;
2) and phase shifting is carried out on the rectification side of the system, so that the voltage of a direct current line is quickly reduced, the voltage reference value of the inversion side is quickly reduced to a new fixed value, and the limit value of the trigger angle of the inversion side is reduced.
Performing a commutation station phase shift comprising: and shifting the trigger angle of the rectifying station to 120 degrees, and delaying for 50ms to shift the trigger angle to 160 degrees after the direct current of the rectifying station is less than 0.05 pu.
The direct-current voltage reference value is usually 1pu, a voltage regulating instruction is sent to the inverter side voltage controller, and the direct-current voltage reference value is reduced to 0-0.5 pu. Preferably, directly down to 0. The inverter side voltage controller adjusts the direct current voltage with the reference value as a target so that the direct current voltage is gradually reduced.
The inverter station firing angle limit is typically 120 degrees or 135 degrees. And sending a phase modulation instruction to the inverter station voltage controller, and reducing the trigger angle limit value of the inverter station to 105-110 degrees. Preferably to the lowest value of the allowed firing angle limit. The trigger angle limit value is a lower limit value, and the trigger angle is reduced by reducing the lower limit value of the trigger angle, so that the direct-current voltage is reduced.
3) After the direct-current voltages of the rectifier station and the inverter station are lower than 0.6pu, closing a high-speed parallel switch HSS of the third station, and advancing the step 4); if the direct-current voltage of the rectifier station and the inverter station is not lower than 0.6pu within the set time, the switching fails, the high-speed parallel switch HSS of the third station is not closed, and the isolating knives on two sides of the high-speed parallel switch HSS of the third station are disconnected.
4) And restarting the rectifying station and the inverter station, recovering the phase of the rectifying station, and recovering the direct-current voltage reference value and the trigger angle limit value of the inverter station.
In the existing process of reducing the direct current voltage, the reference value or the trigger angle of the output voltage of the inversion side is not adjusted, and the voltage reduction speed is slow. The comparison of the time taken to reduce the dc line voltage to a fixed value using the prior art scheme and the inventive art scheme is shown in table 1.
TABLE 1 comparison of the time taken for two technical solutions to reduce the DC line voltage to a constant value
As can be seen from table 1, compared with the prior art, the technical scheme of the present invention can rapidly reduce the voltage of the dc line, greatly reduce the waiting time required for the third station to be put into operation, and reduce the current-cutoff time of the dc system.
In summary, according to the third station fast switching method of the parallel three-terminal dc power transmission system of the present invention, after receiving the third station switching command, the isolation switches on the two sides of the high-speed parallel switch HSS of the third station are closed; performing phase shift on the rectifying station, and simultaneously reducing the direct-current voltage reference value and the trigger angle limit value of the inverter station; after the direct-current voltages of the rectifier station and the inverter station are lower than a set threshold value, a high-speed parallel switch HSS of a third station is closed; and restarting the rectifying station and the inverter station, recovering the phase of the rectifying station, and recovering the direct-current voltage reference value and the trigger angle limit value of the inverter station. The invention increases the treatment to the inversion side and can quickly reduce the voltage of the direct current line. The method is suitable for a multi-terminal direct current transmission system, reduces the impact on primary equipment such as HSS switches and the like when the converter station is put into operation, and can reduce the current break time of a direct current system when the converter station is put into operation so as to reduce the influence on an alternating current system.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (7)
1. A third station rapid switching method of a parallel three-terminal direct-current transmission system is characterized by comprising the following steps:
after receiving a third station input command, closing the isolation knives on two sides of the high-speed parallel switch HSS of the third station;
performing phase shift on the rectifying station, and simultaneously reducing the direct-current voltage reference value and the trigger angle limit value of the inverter station;
after the direct-current voltages of the rectifier station and the inverter station are lower than a set threshold value, a high-speed parallel switch HSS of a third station is closed; and restarting the rectifying station and the inverter station, canceling the phase shift signal of the rectifying station, and recovering the direct-current voltage reference value and the trigger angle limit value of the inverter station.
2. The method of claim 1, wherein the performing a commutation station phase shift comprises: and shifting the trigger angle of the rectifying station to 120 degrees, and delaying for 50ms to shift the trigger angle to 160 degrees after the direct current of the rectifying station is less than 0.05 pu.
3. The method for rapidly switching the third station of the parallel three-terminal direct-current transmission system according to claim 1 or 2, wherein the step of reducing the direct-current voltage reference value of the inverter station comprises reducing the direct-current voltage reference value of the inverter station from 1pu to 0-0.5 pu.
4. The method of claim 3, wherein reducing the inverter station DC voltage reference comprises: and sending a voltage regulating instruction to the inverter station voltage controller, and reducing the direct-current voltage reference value of the inverter station from 1pu to 0 pu.
5. The method of claim 3, wherein reducing the inverter station firing angle limit comprises: and sending a phase modulation instruction to the inverter station voltage controller, and reducing the trigger angle limit value of the inverter station to 105-110 degrees.
6. The method for rapidly switching the third station of the parallel three-terminal direct-current transmission system according to claim 1 or 2, wherein the high-speed parallel switch HSS of the third station is closed after the direct-current voltage of the rectifying station and the direct-current voltage of the inverting station are lower than 0.6 pu.
7. The method of claim 6, wherein if the DC voltages of the rectification station and the inversion station are not lower than 0.6pu within a predetermined time, the switching fails, the HSS is not closed, and the isolation switches on two sides of the HSS are opened.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011269828.9A CN114498601A (en) | 2020-11-13 | 2020-11-13 | Method for quickly putting third station of parallel three-terminal direct-current transmission system into operation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011269828.9A CN114498601A (en) | 2020-11-13 | 2020-11-13 | Method for quickly putting third station of parallel three-terminal direct-current transmission system into operation |
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| Publication Number | Publication Date |
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| CN114498601A true CN114498601A (en) | 2022-05-13 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202011269828.9A Pending CN114498601A (en) | 2020-11-13 | 2020-11-13 | Method for quickly putting third station of parallel three-terminal direct-current transmission system into operation |
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| CN (1) | CN114498601A (en) |
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- 2020-11-13 CN CN202011269828.9A patent/CN114498601A/en active Pending
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