A method and system for realizing triple main protection of transmission lines based on channel switching

Abstract

A method and system for realizing triple main protection of power transmission lines based on channel switching, including connecting dual optical fiber channels and 5G channels to the main line of the power transmission line and a longitudinal protection device corresponding to the channels; monitoring the dual optical fiber channels and the 5G channels, and judging whether the dual optical fiber channels are operating normally, if at least one channel in the dual optical fiber channels is operating normally, the power transmission line uses optical fiber longitudinal differential protection as the main protection, and performs corresponding 5G protection according to the communication and timing conditions; if both the dual optical fiber channels are not operating normally, the optical fiber longitudinal differential protection is not performed and it is judged whether the communication of the 5G channel is normal, if the communication of the 5G channel is abnormal, the optical fiber longitudinal differential protection, the 5G longitudinal differential protection, and the 5G longitudinal distance protection are not performed; if the communication of the 5G channel is normal, it is judged whether the timing of the 5G channel is normal, and the corresponding 5G protection is performed according to the timing conditions. The present invention can greatly increase the reliability of the relay protection device.

Description

Technical Field

[0001] The present invention belongs to the field of line relay protection, and more specifically, relates to a method and system for realizing triple main protection of a transmission line based on channel switching. Background Art

[0002] With the extensive application of new energy sources such as wind power and photovoltaics, the scale of the power grid continues to expand, the structure becomes increasingly complex, the coupling between UHV AC and DC becomes increasingly close, and the continuous application of a large number of power electronic equipment makes the power grid's ability to withstand faults gradually decrease, and the performance requirements of relay protection become more and more stringent. When the power grid topology is complex or requires multi-level coordination, the existing power communication technology has gradually failed to meet the development needs of the power system. There are problems such as difficulty in locating communication channel faults and insufficient reliability of long-distance communications. Therefore, it is necessary to study new power information interaction communication technologies suitable for the field of relay protection.

[0003] At present, the main power information communication technologies include microwave communication, carrier communication, optical fiber transmission and wireless communication. Microwave communication has insurmountable defects such as susceptibility to interference, poor stability and small transmission capacity. Carrier communication also has problems such as easy aging of equipment, high failure rate, complex line interfaces, many bridges, large attenuation and poor anti-interference ability.

[0004] The transmission medium of the fiber optic channel is OPGW and ADSS overhead optical cables. Fiber optic communication has strong anti-interference ability, large information transmission capacity and high transmission quality. It has excellent communication characteristics and has gradually become the mainstream communication method for medium and high voltage power systems. However, the construction of fiber optic networks is difficult and costly. The power grid covers a wide area, the power engineering technology is diversified, and the power system construction cycle is long. As a secondary network attached to the power grid, the construction of fiber optic networks is also very difficult and costly. In addition, the construction of fiber optic networks in distribution networks is currently in a serious lagging state, resulting in insufficient automation of distribution networks, which seriously affects the reliability of power supply. In the case of super-high cranes, ice disasters, etc., it may be severely damaged, affecting the investment in longitudinal protection.

[0005] Wireless communication is mainly used in power distribution networks, and its mainstream communication solutions are 230 MHz power wireless private network and 4G power wireless private network based on TD-LTE technology. Compared with optical fiber network, power wireless private network has lower construction cost and convenient maintenance, but based on the essential characteristics of wireless technology, power wireless private network also has some shortcomings, such as: limited frequency band and bandwidth, long delay, insufficient security and low reliability.

[0006] The International Telecommunication Union has introduced the fifth generation mobile communication technology (5G communication), which has the characteristics of short delay, large capacity, and high bandwidth. The present invention is applied in the field of relay protection to improve the real-time and reliability of power system information communication and reduce the cost of power information communication, providing a practical and feasible method. Summary of the invention

[0007] In order to solve the deficiencies in the prior art, the purpose of the present invention is to provide a method and system for implementing triple main protection of transmission lines based on channel switching, so as to improve the reliability of long-distance communication and meet the needs of the power system.

[0008] The present invention adopts the following technical solution.

[0009] A method for implementing triple main protection of a transmission line based on channel switching comprises the following steps:

[0010] Step 1: Connect the dual optical fiber channel and the 5G channel to the main line of the transmission line and the longitudinal protection device corresponding to the channel;

[0011] Step 2, monitor the dual fiber channels and the 5G channel, and determine whether the dual fiber channels are operating normally. If at least one of the dual fiber channels is operating normally, the transmission line uses the fiber longitudinal differential protection as the main protection, executes the fiber longitudinal differential protection, and controls the circuit breaker to trip by the fiber longitudinal differential protection, and enters step 3. If both dual fiber channels are not operating normally, the fiber longitudinal differential protection is not executed and enters step 4;

[0012] Step 3: Determine whether the communication and timing of the 5G channel are normal, and perform corresponding 5G protection according to the communication and timing conditions;

[0013] Step 4, determine whether the communication of the 5G channel is normal. If the communication of the 5G channel is abnormal, the optical fiber longitudinal differential protection, 5G longitudinal differential protection, and 5G longitudinal distance protection will not be executed; if the communication of the 5G channel is normal, execute step 5;

[0014] Step 5: Determine whether the 5G channel timing is normal, and perform corresponding 5G protection according to the timing situation.

[0015] The longitudinal protection corresponding to the dual optical fiber channel described in step 1 is optical fiber longitudinal differential protection; the longitudinal protection corresponding to the 5G channel is 5G longitudinal differential protection and 5G longitudinal distance protection.

[0016] Fiber optic longitudinal differential protection adopts sampling value differential; 5G longitudinal differential protection adopts vector differential.

[0017] Step 3 includes:

[0018] 5G protection execution situation 1: If the communication and timing of the 5G channel are normal, the 5G pilot differential protection and 5G pilot distance protection are executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot differential protection and 5G pilot distance protection action messages are sent, but the 5G pilot differential protection and 5G pilot distance protection do not control the circuit breaker to trip;

[0019] 5G protection execution situation 2: If the communication of the 5G channel is normal but the timing is abnormal, the 5G pilot distance protection is executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot distance protection action message is sent, but the 5G pilot distance protection does not control the circuit breaker to trip; the 5G pilot differential protection is not executed;

[0020] 5G protection execution condition 3: If the communication and timing of the 5G channel are abnormal, the 5G pilot differential protection and 5G pilot distance protection will not be enabled;

[0021] The method to determine whether the dual fiber channel is faulty is as follows:

[0022] When dual fiber channels are running, if any of the fiber channels cannot receive data for 30 ms continuously, or the accumulated frame loss or bit error exceeds 20 frames within 1 s, the fiber channel stops running and is judged to be faulty.

[0023] The criteria for judging 5G channel communication abnormality are: the longitudinal protection devices at both ends of the line cannot receive data for 30 ms continuously, or the accumulated frame loss or bit error exceeds 20 frames within 1 s.

[0024] The criteria for judging 5G channel timing anomaly are:

[0025] When the 5G channel is running and communication is normal, if the 5G channel delay is greater than 15ms, it is judged that the 5G channel timing is abnormal.

[0026] Step 5 specifically includes:

[0027] If the timing of the 5G channel is normal, the 5G longitudinal differential protection will serve as the main protection and execute the 5G longitudinal differential protection. The 5G longitudinal differential protection will control the circuit breaker to trip. At the same time, the 5G longitudinal distance protection will be executed and the 5G longitudinal distance protection action message will be sent. However, the 5G longitudinal distance protection will not control the circuit breaker to trip.

[0028] If the timing of the 5G channel is abnormal, the 5G longitudinal distance protection will serve as the main protection, and the 5G longitudinal distance protection will be executed, and the circuit breaker will be tripped by the 5G longitudinal distance protection; the 5G longitudinal differential protection will not be executed.

[0029] The contents recorded in the 5G longitudinal differential protection and 5G longitudinal distance protection action message include the execution time of the 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase of the main line of the transmission line.

[0030] The triple main protection implementation system of the transmission line based on channel switching includes a fault identification module, a channel selection module, and a storage module:

[0031] The fault identification module is used to identify whether the optical fiber channel and 5G channel are abnormal;

[0032] The channel selection module is used to switch the fiber channel or 5G channel as the main line protection;

[0033] The storage module is used to store the execution time of 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase difference of the main line of the transmission line. The beneficial effect of the present invention is that, compared with the prior art, the present invention realizes that when the optical fiber longitudinal differential protection stops due to an abnormal optical fiber channel, the main protection is not lost, and the 5G longitudinal differential protection or the 5G longitudinal distance protection is switched as the main protection, which greatly improves the reliability of relay protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a flow chart of a method for realizing triple main protection of a power transmission line based on channel switching of the present invention;

[0035] Figure 2 It is a schematic diagram of a 5G protection system of a method for realizing triple main protection of a transmission line based on channel switching of the present invention.

[0036] In the attached figure, M and N represent the two ends of the line, CB represents the circuit breaker, TA represents the current transformer, and CPE represents the front-end 5G signal receiving equipment. DETAILED DESCRIPTION

[0037] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present application.

[0038] A method for implementing triple main protection of transmission lines based on channel switching. Because this method involves the coexistence of three main protections, it involves a total of six operating modes. The overall logical relationship is as follows Figure 1 The schematic diagram of the protection access system is shown in Figure 2 , protection devices are connected at both ends of the protected line. Specifically, a circuit breaker CB and a current transformer TA are sequentially arranged on one side close to the end of the line. The circuit breaker CB and the current transformer TA are connected to a differential protection device. A 5G signal receiving device is pre-placed on the differential protection device. The protection implementation method of the present invention specifically includes the following steps:

[0039] Step 1: Connect the dual optical fiber channel and the 5G channel to the main line of the transmission line and the longitudinal protection device corresponding to the channel;

[0040] The longitudinal protection corresponding to the dual-fiber channel is the fiber longitudinal differential protection; the longitudinal protection corresponding to the 5G channel is the 5G longitudinal differential protection and the 5G longitudinal distance protection, of which the fiber longitudinal differential protection adopts the sampling value differential, and the 5G longitudinal differential protection adopts the vector differential. The reason for this choice is mainly to consider the economy of this technology when applied. The amount of data transmitted when the sampling value differential is adopted is large. If the sampling value differential is adopted for the 5G longitudinal differential protection, it is bound to increase the daily traffic interaction, causing the 5G longitudinal differential protection to lose its economy. As for the vector differential, because the vector is transmitted, the amount of data transmitted is smaller than the sampling value, so the 5G longitudinal differential protection adopts the vector differential.

[0041] At the same time, the two can achieve logical complementation when the fiber channel and 5G channel are intact.

[0042] Both sampling value differential and vector differential are mature technologies, but sampling value differential may malfunction when the harmonic component is large. Vector differential uses the vector value calculated by Fourier filter, which is naturally superior to sampling value differential. Therefore, within 30ms after the protection is started, using whether the vector differential is activated as the opening condition of the sampling value differential can effectively prevent the sampling value differential malfunction caused by harmonics.

[0043] Step 2: monitor the dual optical fiber channels and 5G channels in step 1 in real time, and determine whether the dual optical fiber channels are operating normally. If at least one channel in the dual optical fiber channels is operating normally, the transmission line uses the optical fiber longitudinal differential protection as the main protection, executes the optical fiber longitudinal differential protection, and controls the circuit breaker to trip by the optical fiber longitudinal differential protection, and enters step 3. If both dual optical fiber channels are not operating normally, the optical fiber longitudinal differential protection is not executed and enters step 4;

[0044] Step 3: Determine whether the communication and timing of the 5G channel are normal, and perform corresponding 5G protection according to the communication and timing conditions;

[0045] Specifically,

[0046] If the communication and timing of the 5G channel are normal, the 5G pilot differential protection and 5G pilot distance protection are executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot differential protection and 5G pilot distance protection action messages are sent, but the 5G pilot differential protection and 5G pilot distance protection do not control the circuit breaker to trip;

[0047] If the communication of the 5G channel is normal but the timing is abnormal, the 5G pilot distance protection is executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot distance protection action message is sent, but the 5G pilot distance protection does not control the circuit breaker to trip; the 5G pilot differential protection is not executed;

[0048] If the communication and timing of the 5G channel are abnormal, the 5G pilot differential protection and 5G pilot distance protection will not be enabled;

[0049] Step 4, determine whether the communication of the 5G channel is normal. If the communication of the 5G channel is abnormal, the optical fiber longitudinal differential protection, 5G longitudinal differential protection, and 5G longitudinal distance protection will not be executed, that is, all main protections will be exited; if the communication of the 5G channel is normal, execute step 5;

[0050] Step 5, determine whether the timing of the 5G channel is normal. If the timing of the 5G channel is normal, the 5G longitudinal differential protection will serve as the main protection, execute the 5G longitudinal differential protection, and control the circuit breaker tripping by the 5G longitudinal differential protection. At the same time, the 5G longitudinal distance protection will be executed, and the 5G longitudinal distance protection action message will be sent, but the 5G longitudinal distance protection will not control the circuit breaker tripping; if the timing of the 5G channel is abnormal, the 5G longitudinal distance protection will serve as the main protection, execute the 5G longitudinal distance protection, and control the circuit breaker tripping by the 5G longitudinal distance protection; the 5G longitudinal differential protection will not be executed.

[0051] The method to determine whether the dual fiber channel is faulty is as follows:

[0052] When dual fiber channels are running, if any of the fiber channels cannot receive data for 30 ms continuously, or the accumulated frame loss or bit error exceeds 20 frames within 1 s, the fiber channel will stop running and be judged as faulty. Channel failure exit means that the data of the channel will no longer be used for calculation at this time, but the channel detection logic is still running and will always detect whether the channel has recovered;

[0053] The method to determine whether the 5G channel communication is abnormal is as follows:

[0054] When the 5G channel is running, if the longitudinal protection devices at both ends of the line cannot receive data for 30 ms continuously, or the cumulative frame loss or bit error of the 5G channel exceeds 20 frames within 1 second, the 5G channel will stop running and the 5G channel communication will be judged to be abnormal;

[0055] The method to determine whether the 5G channel timing is abnormal is as follows:

[0056] When the 5G channel is running and communication is normal, if the 5G channel delay is greater than 15ms, it is judged that the 5G channel timing is abnormal;

[0057] The contents recorded in the 5G longitudinal differential protection and 5G longitudinal distance protection action message include the execution time of the 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase of the main line of the transmission line.

[0058] The present invention also provides a system for implementing the above-mentioned transmission line triple main protection implementation method based on channel switching, including a data acquisition and analysis module, a fault identification module, a 5G timing identification module, and a channel selection module.

[0059] The fault identification module is used to identify whether the optical fiber channel and 5G channel are abnormal;

[0060] The channel selection module is used to switch the fiber channel or 5G channel as the main line protection;

[0061] The storage module is used to store the execution time of 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase difference of the main line of the transmission line.

[0062] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, but not to limit the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for implementing triple main protection of a transmission line based on channel switching, characterized in that: The following steps are involved: Step 1: Connect the dual optical fiber channel and the 5G channel to the main line of the transmission line and the longitudinal protection device corresponding to the channel; Step 2, monitor the dual fiber channels and the 5G channel, and determine whether the dual fiber channels are operating normally. If at least one of the dual fiber channels is operating normally, the transmission line uses the fiber longitudinal differential protection as the main protection, executes the fiber longitudinal differential protection, and controls the circuit breaker to trip by the fiber longitudinal differential protection, and enters step 3; If both optical fiber channels are not operating normally, the optical fiber longitudinal differential protection will not be performed and the process will go to step 4; Step 3: Determine whether the communication and timing of the 5G channel are normal, and perform corresponding 5G protection according to the communication and timing conditions; 5G protection execution situation 1: If the communication and timing of the 5G channel are normal, the 5G pilot differential protection and 5G pilot distance protection are executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot differential protection and 5G pilot distance protection action messages are sent, but the 5G pilot differential protection and 5G pilot distance protection do not control the circuit breaker to trip; 5G protection execution situation 2: If the communication of the 5G channel is normal but the timing is abnormal, the 5G pilot distance protection is executed while the optical fiber pilot differential protection is used as the main protection, and the 5G pilot distance protection action message is sent, but the 5G pilot distance protection does not control the circuit breaker to trip; the 5G pilot differential protection is not executed; 5G protection execution condition 3: If the communication and timing of the 5G channel are abnormal, the 5G pilot differential protection and 5G pilot distance protection will not be enabled; Step 4, determine whether the communication of the 5G channel is normal. If the communication of the 5G channel is abnormal, the optical fiber longitudinal differential protection, 5G longitudinal differential protection, and 5G longitudinal distance protection will not be executed; if the communication of the 5G channel is normal, execute step 5; Step 5: Determine whether the 5G channel timing is normal, and perform corresponding 5G protection according to the timing situation; If the timing of the 5G channel is normal, the 5G longitudinal differential protection will serve as the main protection and execute the 5G longitudinal differential protection. The 5G longitudinal differential protection will control the circuit breaker to trip. At the same time, the 5G longitudinal distance protection will be executed and the 5G longitudinal distance protection action message will be sent. However, the 5G longitudinal distance protection will not control the circuit breaker to trip. If the timing of the 5G channel is abnormal, the 5G longitudinal distance protection will serve as the main protection, and the 5G longitudinal distance protection will be executed, and the circuit breaker will be tripped by the 5G longitudinal distance protection; the 5G longitudinal differential protection will not be executed.

2. The method for realizing triple main protection of power transmission lines based on channel switching according to claim 1 is characterized in that: In step 1, the longitudinal protection corresponding to the dual optical fiber channel is optical fiber longitudinal differential protection; the longitudinal protection corresponding to the 5G channel is 5G longitudinal differential protection and 5G longitudinal distance protection.

3. The method for realizing triple main protection of power transmission lines based on channel switching according to claim 2 is characterized in that: Fiber optic longitudinal differential protection adopts sampling value differential; 5G longitudinal differential protection adopts vector differential.

4. The method for implementing triple main protection of power transmission lines based on channel switching according to claim 1 is characterized in that: The method to determine whether the dual fiber channel is faulty is as follows: When dual fiber channels are running, if any of the fiber channels cannot receive data for 30 ms continuously, or the accumulated frame loss or bit error exceeds 20 frames within 1 s, the fiber channel stops running and is judged to be faulty.

5. The method for realizing triple main protection of power transmission lines based on channel switching according to claim 1 is characterized in that The criteria for judging 5G channel communication abnormality are: the longitudinal protection devices at both ends of the line cannot receive data for 30 ms continuously, or the accumulated frame loss or bit error exceeds 20 frames within 1 s.

6. The method for realizing triple main protection of power transmission lines based on channel switching according to claim 1 is characterized in that The criteria for judging the abnormality of 5G channel timing are: When the 5G channel is running and communication is normal, if the 5G channel delay is greater than 15ms, it is judged that the 5G channel timing is abnormal.

7. The method for realizing triple main protection of power transmission lines based on channel switching according to claim 1 is characterized in that: The contents recorded in the 5G longitudinal differential protection and 5G longitudinal distance protection action message include the execution time of the 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase of the main line of the transmission line.

8. A transmission line triple main protection implementation system based on channel switching for implementing the transmission line triple main protection implementation method based on channel switching as described in any one of claims 1 to 7, characterized in that: Including fault identification module, channel selection module, storage module, The fault identification module is used to identify whether the optical fiber channel and 5G channel are abnormal; The channel selection module is used to switch the fiber channel or 5G channel as the main line protection; The storage module is used to store the execution time of 5G longitudinal differential protection and 5G longitudinal distance protection, the fault current of the main line of the transmission line, and the fault phase difference of the main line of the transmission line.

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