Automatic switching device for backup power line of superconducting cable and operation method thereofTechnical Field
The invention relates to the technical field of superconducting cables, in particular to an automatic switching device for a standby power line of a superconducting cable and an operation method thereof.
Background
The superconducting cable is applied to a power system at present, the operation experience is lacked, the operation reliability is yet to be verified, and in order to ensure that the power supply to a user is not affected after the superconducting cable is cut off, automatic input measures of a standby power supply are needed to be made.
The current power system adopts a standby power supply automatic switching device (standby power automatic switching) to realize that the standby power supply is automatically switched into to quickly restore power supply when a main power supply line is lost, and the working principle is as follows: when the standby automatic switching device detects that the main power supply is not powered (no voltage) and the standby power supply is powered (voltage), the main power supply circuit breaker is automatically and immediately tripped, and when the main power supply circuit breaker is detected to be indeed tripped, the standby power supply circuit breaker is immediately and automatically put into operation.
Superconducting cable faults are generally divided into two categories: when the superconducting cable has serious faults (such as serious faults of liquid nitrogen pipeline inlet pressure, abnormal outlet temperature, liquid nitrogen pipeline leakage and the like of the superconducting cable), the superconducting cable should stop running immediately, and when the superconducting cable has slight faults (such as liquid nitrogen pump faults, refrigeration system failure and the like and is not in serious faults), the superconducting cable can run for a short time without stopping running immediately, and the superconducting cable should be cut off and overhauled by both the above two faults and is automatically put into a standby power supply line.
Because the fault characteristics and the detection and discrimination methods of the superconducting cable are different from those of the conventional line, for example, when the superconducting cable has a slight fault, the voltage of the main power supply line is normal, and the conventional automatic standby power supply switching device cannot adapt to the fault.
Therefore, how to enable the automatic switching device of the standby power supply to be applied to the superconducting cable power supply system is a technical problem which needs to be solved by those skilled in the art.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, the present invention provides an automatic switching device for a backup power line of a superconducting cable and an operation method thereof, which are implemented to enable the automatic switching device of the backup power to be applied to a superconducting cable power supply system, automatically switch on the backup power under the condition that the superconducting cable is severely broken and cut off, automatically and rapidly switch on the backup power line without power failure under the condition that the superconducting cable is slightly broken, and then cut off the superconducting cable, thereby avoiding the defects of low efficiency and inconvenient operation caused by manual opening and closing.
To achieve the above object, the present invention discloses an automatic switching device for a backup power line of a superconducting cable, including a superconducting cable line and a backup line; a second circuit breaker is arranged between the superconducting cable line and the load side substation bus, and is connected with a second line protection, and the second line protection controls the opening and closing; a fourth circuit breaker is arranged between the standby line and the bus of the load side transformer substation, and is connected with a fourth line protection, and is controlled to be opened and closed by the fourth line protection; the load side transformer substation is provided with a superconducting cable body protection and standby power supply automatic switching device.
The second line protection device, the fourth line protection device, the superconducting cable body protection device and the standby power supply automatic switching device jointly form an automatic switching system of the superconducting cable standby power supply line.
Judging the severity of the fault of the superconducting cable through electric quantity and non-electric quantity by the superconducting cable body protection, outputting a tripping signal to the second line protection when the superconducting cable has serious fault, and sending an alarm signal to the automatic switching device of the standby power supply when the superconducting cable has slight fault;
the automatic switching device of the standby power supply judges whether the standby power supply is automatically switched on or switched to a standby line or not according to the voltage sampling value and the switching value which are input from the outside, and outputs switching-on and switching-off dividing and dividing switching-on commands of the standby power supply according to the switching value.
Preferably, a first breaker is arranged between the superconducting cable line and the power side substation bus; a third circuit breaker is arranged between the standby line and the power side substation bus;
in normal operation, the first circuit breaker and the second circuit breaker are both in a closed state; the third circuit breaker is in a closed state, and the fourth circuit breaker is in a breaking state;
three-phase voltage transformers are respectively arranged on the load transformer substation side bus and the standby line;
the first circuit breaker and the third circuit breaker are respectively connected with a first circuit protection and a third circuit protection; the first line protection controls the opening and closing of the first circuit breaker, and the third line protection controls the opening and closing of the third circuit breaker;
and the first line protection and the second line protection as well as the third line protection and the fourth line protection are connected through a special optical fiber channel to realize communication.
More preferably, the first line protection, the second line protection, the third line protection and the fourth line protection are microcomputer split-phase current differential protection devices, and comprise a complete backup protection module, a measurement and control module and an operation box module;
each microcomputer type split-phase current differential protection device is used for main protection and backup protection of the corresponding superconducting cable line or the corresponding standby line.
More preferably, the electrical quantity comprises a current value and/or a voltage value; the non-electrical quantity comprises warning information such as liquid nitrogen temperature, pipeline pressure value and/or refrigeration system and circulation system faults;
the voltage sampling value refers to a three-phase alternating current voltage value of the load side substation bus and the standby line, which are input through a data acquisition system;
the switching value input refers to signals such as the protection alarm signal of the superconducting cable body, the tripping positions of the second circuit breaker and the fourth circuit breaker and the like which are input through a switching value input/output system.
The output command refers to an automatic switching-on, switching-off and dividing switching-on command of the standby power supply output by the switching value input/output system.
The invention also provides an operation method of the automatic switching device for the backup power supply line of the superconducting cable, wherein the operation logic of the automatic switching device of the backup power supply is as follows:
when the superconducting cable line has short-circuit faults, the line protection devices on two sides of the superconducting cable timely judge the line faults according to preset algorithm logic and trip the circuit breakers on two sides;
when the superconducting cable line has a short circuit fault or a serious non-electrical quantity fault, the superconducting cable body protection sends a tripping signal to the second line protection; the second line protection trips the second circuit breaker, and simultaneously issues a trip command to the first line protection via a dedicated fiber channel to trip the first circuit breaker;
when the automatic switching device of the standby power supply detects that the three-phase alternating voltage of the bus of the transformer substation at the load side is lost and the three-phase alternating voltage of the standby line is normal through the voltage sampling value input from the outside, a tripping command is sent to the second line to protect and trip the second circuit breaker;
when the automatic switching device of the standby power supply detects that the second circuit breaker is indeed tripped through switching value input, a switching-on command is sent to the fourth circuit protection to switch on the fourth circuit breaker;
when the superconducting cable line has a general fault such as a liquid nitrogen pump fault, a refrigeration system failure and other slight faults which do not need to trip immediately, under the condition that the superconducting cable line can continue to run for 1 to 30 minutes, the superconducting cable body is protected to send an alarm signal to the automatic switching device of the standby power supply;
the automatic switching device of the standby power supply detects that the three-phase alternating voltage of the standby line is normal through a voltage sampling value input from the outside, and sends a closing command to the fourth line protection to close the fourth circuit breaker when detecting that the fourth circuit breaker is indeed opened through switching value input;
and when the fourth circuit breaker is detected to be indeed closed, tripping the second circuit breaker by a tripping command, and simultaneously, tripping the first circuit breaker by a tripping command sent to the first circuit breaker.
The invention has the beneficial effects that:
the invention can ensure that the superconducting cable can be automatically and quickly switched into the standby power line and restore the power supply after being cut off under serious faults, and can automatically and quickly switch into the standby power line without power failure and then cut off the superconducting cable under slight faults, thereby avoiding the defects of low efficiency and inconvenient operation caused by manual opening and closing.
The conception, specific structure, and technical effects of the present invention will be further described with reference to the accompanying drawings to fully understand the objects, features, and effects of the present invention.
Drawings
Fig. 1 shows a configuration diagram of an embodiment of the present invention.
FIG. 2 illustrates a logic diagram of the operation of an embodiment of the present invention.
Detailed Description
Examples
As shown in fig. 1, an automatic switching device for a backup power line of a superconducting cable includes a superconducting cable line and a backup line; a second breaker DL21 is arranged between the superconducting cable line and the load side substation bus, the second breaker DL21 is connected with a second line protection 21, and the second line protection 21 controls the opening and closing; a fourth breaker DL22 is arranged between the standby line and the load side substation bus, the fourth breaker DL22 is connected with a fourth line protection 22, and the opening and closing of the fourth line protection 22 is controlled; the load side transformer substation is provided with a superconducting cable body protection and standby power supply automatic switching device.
The second line protection device, the fourth line protection device, the superconducting cable body protection device and the standby power supply automatic switching device jointly form an automatic switching system of the superconducting cable standby power supply line.
The superconducting cable body protection judges the severity of the fault of the superconducting cable through the electric quantity and the non-electric quantity, outputs a tripping signal to the second line protection 21 when the superconducting cable has serious fault, and sends an alarm signal to the automatic switching device of the standby power supply when the superconducting cable has slight fault;
the automatic switching device of the standby power supply judges whether the automatic switching device should be put into or switched to the standby line or not through the voltage sampling value and the switching value which are input from the outside, and outputs switching commands of switching the standby power supply into or switched to the switching device by the switching value.
The automatic switching device of the standby power supply follows the technical condition of automatic switching device of the standby power supply (the standard DL/T526 of the electric power industry of the people's republic of China), and the automatic switching device of the standby power supply commonly used in the electric power industry at present can be adopted, such as PCS-9651DB-D of Nanjing Nanny relay protection engineering Co., WBT-822C of permitted electric power stock Co., beijing square relay protection engineering Co., CSD-246 and the like.
The principle of the invention is as follows:
when a more serious fault occurs to the superconducting cable, such as a short circuit fault of the superconducting cable body, a fault that the liquid nitrogen pressure at an inlet of the superconducting cable is lower than a lower limit, the liquid nitrogen temperature at an inlet of the superconducting cable is higher than an upper limit, leakage of a liquid nitrogen pipeline and the like, the superconducting cable is tripped out of the superconducting cable to isolate the fault by the protection of the superconducting cable body or the relay protection action of the system, and then a standby power supply automatic switching device is used for switching on a standby power supply line, wherein the situation requires 2s to 3s of power failure; when the superconducting cable has general faults such as liquid nitrogen pump faults, refrigerating system faults and the like which do not need to trip immediately, a protection and protection alarm signal of the superconducting cable body is given to the automatic standby power switching device, the automatic standby power switching device sends a switching-on command to switch on the standby power line, and when the automatic standby power switching device detects that the standby power line is actually switched on, the tripping command is used for cutting off the superconducting cable, so that the situation that the superconducting cable is switched to the standby line without power failure can be realized, and the uninterrupted power supply is ensured.
In certain embodiments, a first circuit breaker DL11 is provided between the superconducting cabling and the power side substation bus bar; a third circuit breaker DL12 is arranged between the standby line and the power side substation bus;
in normal operation, the first breaker DL11 and the second breaker DL21 are in a closed state, and the load side substation bus is communicated with the power supply side substation bus through a superconducting cable line to realize power supply; the third circuit breaker DL12 is in a closed state, the fourth circuit breaker DL22 is in a brake-separating state, and hot standby of a standby line is formed;
three-phase voltage transformers PT21 and PT22 are respectively arranged on the bus and the standby line of the load side transformer substation so as to measure the voltages of the corresponding bus and line;
the first circuit breaker DL11 and the third circuit breaker DL12 are connected to the first line protection 11 and the third line protection 12, respectively; the first line protection 11 controls the opening and closing of the first circuit breaker DL11, and the third line protection 12 controls the opening and closing of the third circuit breaker DL12;
communication is realized between the first line protection 11 and the second line protection 21, and between the third line protection 12 and the fourth line protection 22 through special optical fiber channel connection.
In some embodiments, the first line protection 11, the second line protection 21, the third line protection 12 and the fourth line protection 22 are all microcomputer split-phase current differential protection devices, and include a complete backup protection module, a measurement and control module and an operation box module;
each microcomputer type split-phase current differential protection device is used for main protection and backup protection of a corresponding superconducting cable line or a corresponding standby line, and can complete the switching-on and switching-off operation functions of a corresponding first circuit breaker DL11, a corresponding second circuit breaker DL21, a corresponding third circuit breaker DL12 and a corresponding fourth circuit breaker DL 22.
In certain embodiments, the electrical quantity includes a current value and/or a voltage value; the non-electrical quantity comprises liquid nitrogen temperature, pipeline pressure value and/or refrigeration system and circulation system fault alarm information;
the voltage sampling value refers to a three-phase alternating current voltage value of a bus and a standby line of the transformer substation on the load side, which are input through a data acquisition system;
the switching value input means signals of the trip positions of the superconducting cable body protection alarm contact, the second circuit breaker DL21 and the fourth circuit breaker DL22, etc. input through the switching value input/output system.
The output command refers to a standby power automatic switching-on, switching-off and dividing switching-on command output by the switching value input/output system.
As shown in fig. 2, the present invention further provides an operation method of the automatic switching device for the backup power line of the superconducting cable, wherein the backup power automatic switching device operates as follows:
when a short circuit fault occurs to the superconducting cable line, the line protection devices at two sides of the superconducting cable timely judge the line fault according to preset algorithm logic and trip the circuit breakers at two sides;
when a short circuit fault or serious non-electrical quantity fault (such as a short circuit fault of the superconducting cable body, a liquid nitrogen pressure of an inlet of the superconducting cable is lower than a lower limit, a liquid nitrogen temperature of the inlet of the superconducting cable is higher than an upper limit, and a liquid nitrogen pipeline leaks) occurs in the superconducting cable line, the superconducting cable body protection sends a tripping signal to the second line protection 21; the second line protection 21 trips the second circuit breaker DL21, while issuing a trip command to the first line protection 11 via the dedicated fibre channel to trip the first circuit breaker DL11;
when the automatic switching device of the standby power supply detects that the three-phase alternating voltage of the superconducting cable line is lost and the three-phase alternating voltage of the standby line is normal through the voltage sampling value input from the outside, a tripping command is sent to the second line protection 21 to trip the second circuit breaker DL21;
when the automatic switching device of the standby power supply detects that the second circuit breaker DL21 is indeed tripped through the switching value input, a switching-on command is sent to the fourth circuit protection 22 to switch on the fourth circuit breaker DL22, so that the power supply to the load side is quickly recovered, and the principle and logic of the automatic switching device of the standby power supply in the operation process are basically the same as those of a conventional automatic switching device of the standby power supply;
when a slight fault such as a liquid nitrogen pump fault, a refrigerating system failure and the like which do not need to trip immediately occurs in the superconducting cable line, under the condition that the superconducting cable line can continue to run for 1 to 30 minutes, the superconducting cable body is protected and sends an alarm signal to the automatic switching device of the standby power supply;
the automatic switching device of the standby power supply detects that the three-phase alternating voltage of the standby line is normal through a voltage sampling value input from the outside, and when detecting that the fourth circuit breaker DL22 is indeed disconnected through switching value input, a switching-on command is sent to be combined with the fourth circuit breaker DL22 to be closed;
when it is detected that the fourth circuit breaker DL22 is actually closed, a tripping command is again issued to the second line protection 21 to trip the second circuit breaker DL21, and a tripping command is issued to the first line protection 11 to trip the first circuit breaker DL11, so that the power supply on the load side is switched to the standby line without power failure, and the superconducting cable is cut off, so that further spread and deterioration of the superconducting cable fault are avoided.
In fig. 2, udz1 and Udz2 are respectively setting values of the decompression and the compression, T11, T21, T31 and T41 are setting values of the delay start time, T12, T22, T32 and T42 are setting values of the delay return time, and all setting values can be set according to the requirements of users.
The foregoing describes in detail preferred embodiments of the present invention. It should be understood that numerous modifications and variations can be made in accordance with the concepts of the invention by one of ordinary skill in the art without undue burden. Therefore, all technical solutions which can be obtained by logic analysis, reasoning or limited experiments based on the prior art by the person skilled in the art according to the inventive concept shall be within the scope of protection defined by the claims.