A Research Method for Hierarchical Protection Configuration in Substations

Abstract

This invention discloses a research method for hierarchical protection configuration in substations. It overcomes the difficulties in setting and coordinating backup protection in existing technologies, where the setting and coordination are based on fixed operating modes. When the grid structure and operating modes change frequently and significantly due to unforeseen circumstances, it can easily lead to mismatch in the operating characteristics of backup protection, potentially causing maloperation or exacerbating accidents.

Description

Technical Field

[0001] This invention relates to the field of substation configuration, and more particularly to a research method for hierarchical protection configuration in substations. Background Technology

[0002] The continuous expansion of AC / DC power grids has led to a gradual increase in power exchange between different regions, making the operation and control of power systems more complex. Existing substation relay protection methods are prone to failure and large-scale power outages, and many grid structures have unreasonable aspects, leading to equipment overload and causing a series of substation operational safety issues.

[0003] For example, a Chinese patent document, "A Hierarchical Protection Method and System for Intelligent Traction Substations," with publication number CN109768527B, proposes a hierarchical protection method and system for intelligent traction substations. The station control layer is configured with an intelligent protection management unit to control the hierarchical protection of the intelligent traction substation. This hierarchical protection includes local protection, station-level protection, and wide-area protection. This method employs a hierarchical protection control system, based on local protection, with station-level and wide-area protection jointly forming a new generation of protection control system. The local protection device integrates merging unit and intelligent terminal functions, simplifying system design. The process layer network adopts a shared network mode of SV and GOOSE. Station-level protection provides redundant protection functions such as circuit breaker failure, simplified busbar, station-level automatic transfer switch, and single-level protection. Wide-area protection realizes the fast selective tripping function of AT traction power supply feeders. The station control layer is configured with an intelligent protection management unit responsible for optimizing configuration and managing various information of the protection devices. However, this method lacks fault diagnosis and post-fault configuration processing, thus having certain shortcomings. Summary of the Invention

[0004] This invention primarily addresses the problem of insufficient backup protection in existing technologies, which can lead to maloperation or escalation of accidents when the grid structure and operation mode undergo frequent and significant changes. It also provides a research method for hierarchical protection configuration in substations.

[0005] The above-mentioned technical problems of the present invention are mainly solved by the following technical solutions:

[0006] This invention includes the following steps: establishing a hierarchical protection system for substations; adding substation protection configurations to the protection system; establishing a fault judgment delay loop based on the protection system; in the above scheme, a hierarchical protection system is first established, then further judges whether a fault has occurred in the power system, and then the protection system responds to the fault in sequence, performing cyclic monitoring of the fault. If the conventional protection system cannot operate normally, a backup protection scheme is activated to prevent major accidents. After layer-by-layer threshold screening, if the fault still exists, tripping protection is provided. This scheme relies on the hierarchical protection system to respond to and handle faults in a simple and orderly manner, avoiding the complex setting process of traditional backup protection, effectively and reliably issuing actions, and improving work efficiency.

[0007] Preferably, the hierarchical protection system includes a local layer, a station area layer, and a wide area layer; layered management of the hierarchical protection system of a substation is beneficial for developing targeted protection schemes for each layer.

[0008] Preferably, the hierarchical protection system includes four protection types: fast protection, basic protection, buffer protection, and local time-delay protection. Basic protection is the first layer of protection, which is activated first when a fault occurs. Buffer protection is the second layer of protection, which is activated after the first layer of protection has taken effect to locate the fault. Local time-delay protection is the last layer of protection, serving as the final line of defense in the conventional protection process. Fast protection is an emergency response protection system that can be activated when other protection measures are not feasible, such as when the specific fault location cannot be determined, effectively preventing major faults from occurring.

[0009] Preferably, the fast protection is activated when basic protection, buffer protection, and local delay protection are ineffective. First, each substation is managed by designated numbered zones. Substations within a range of n numbers use the same fast protection dispatcher, which receives instructions from the monitoring platform for that zone. When a sudden power grid failure or substation loss of voltage occurs in a zone, the monitoring platform issues a command to the dispatcher to trip all substations within that zone and cut off all data transmission and reception channels except for the emergency information channel. The processing results are then uploaded to the monitoring platform. This approach minimizes the number of substations affected under extreme conditions.

[0010] Preferably, the basic protection is based on the wide area layer and the station area layer, and performs real-time filtering according to the type of information transmission. For example, substation safety information is marked, and ordinary messages are received in layers, with priority given to receiving safety information from adjacent substations and instructions from the monitoring platform. When an adjacent substation experiences a loss of power or a grid failure, the marking information transmitted from the substation to the monitoring center or other adjacent substations will change. The target substation will automatically transmit suspicious information to the monitoring platform, and all adjacent substations will enter the buffer protection phase, while the remaining substations will return to normal operation.

[0011] Preferably, the buffer protection is based on the wide-area layer. When a change in the marker information is detected, the monitoring platform will lock the target faulty substation according to the changed marker information, cut off the connection between the target substation and the adjacent substation, and enter the local delay protection stage. The locked target substation cuts off the connection with the adjacent substation, and the adjacent substation performs self-test. If there is a problem, it enters the local delay protection stage; if there is no problem, it returns to normal operation.

[0012] Preferably, the local time-delay protection establishes a fault judgment delay loop based on the station area layer and the local layer. The main process includes a pre-threshold judgment stage: setting an overvoltage step threshold and a delay time Tw. The overvoltage step threshold includes three thresholds: Va, Vb, and Vc. Setting the thresholds allows for step-by-step monitoring, enabling different handling for different levels of substation overvoltage. Every Tw, the monitoring platform sends a voltage monitoring signal to the target substation to determine whether the current voltage Vp is less than Va. If so, it continues to send voltage detection signals for three Tw before releasing the protection state. Otherwise, it enters the backup threshold judgment stage. Setting the delay Tw facilitates system self-checking. If no signal is received after the delay, the target substation immediately trips, and the monitoring platform also reports the situation for processing, which can quickly protect the internal safety of the substation.

[0013] Preferably, in the backup threshold judgment stage, the monitoring platform sends a voltage monitoring signal to the target substation every Tw to determine whether Vp is less than Vb. If so, it sends a step-down signal and a voltage detection signal to the target substation every Tw interval, and monitors in a loop until Vp <= Va. Otherwise, it determines whether Vp is less than Vc. If so, it cuts off the power supply to some important equipment every Tw; otherwise, it sends a trip signal to the target substation.

[0014] The beneficial effects of this invention are: relying on the hierarchical protection system to respond to and isolate faults in a simple and orderly manner, avoiding the complex setting process of traditional backup protection, effectively and reliably issuing actions, and improving work efficiency; in the hierarchical protection process, it can effectively screen and control the target substation, and maximize the safety of the substation. Attached Figure Description

[0015] Figure 1 This is a flowchart of a research method for hierarchical protection configuration in substations according to the present invention. Detailed Implementation

[0016] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0017] Example:

[0018] This embodiment provides a hierarchical protection configuration method for substations, such as... Figure 1 As shown, it includes:

[0019] Establish a hierarchical protection system for substations, including local, substation-area, and wide-area layers. Based on the wide-area and substation-area layers, activate the first layer of conventional protection: basic protection; based on the wide-area layer, activate the second layer of conventional protection: buffer protection; based on the substation-area and local layers, activate the third layer of conventional protection: local time-delay protection. Additional emergency protection measures include: rapid protection.

[0020] When a fault occurs in a substation, protection is provided through the following process:

[0021] Step 1: Determine if the conventional protection can operate successfully. If yes, proceed to Step 2; otherwise, proceed to Step 3.

[0022] Step 2: Enter the basic protection stage. Suspicious information is automatically uploaded to the monitoring platform. Information from each substation is managed in a hierarchical manner. Proceed to Step 4, where each substation performs real-time self-detection.

[0023] Step 3: Implement rapid protection measures for each substation. The monitoring platform sends signals to each substation zone and determines the zone where the fault occurred based on the returned signals, then proceeds to Step 5.

[0024] Step 4: Enter the buffer protection phase, lock the target faulty substation and adjacent substations, cut off the connection with other substations, perform real-time self-detection, and proceed to Step 6.

[0025] Step 5: The monitoring platform sends a trip command to the zone, all substations in the zone trip, the result is transmitted back to the monitoring platform, and uploaded to the relevant departments for action;

[0026] Step 6: Enter the local time delay protection stage, set the delay Tw and overvoltage thresholds Va, Vb and Vc. Delay Tw is used to determine the relationship between the real-time voltage Vp and Va of the substation. Does Vp > Va? If so, proceed to step 7; otherwise, proceed to step 8. If no signal is received after the timeout, proceed to step 5.

[0027] Step 7: Determine if Vp > Vb. If yes, proceed to step 9; otherwise, repeat step 6. If no signal is received within the timeout period, proceed to step 5.

[0028] Step 8: Repeat step 6 three times. If the results are the same, the protection mechanism of the distribution network is released and the network returns to normal operation.

[0029] Step 9: Determine if Vp >= Vc. If yes, proceed to step 5; otherwise, proceed to step 10.

[0030] Step 10: The monitoring platform sends a step-down signal to the substation and repeats step 7.

[0031] It should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for configuring hierarchical protection in a substation, characterized in that, Includes the following steps: S1: Establish a hierarchical protection system for substations, and activate the first layer of conventional protection: basic protection, based on the wide-area layer and the station-area layer. Initiate a second layer of conventional protection on top of the wide-area layer: buffer protection; Based on the station domain layer and the local layer, a third layer of conventional protection is activated: local time-delay protection. Additional emergency protection measures include: rapid protection; S2: Add substation protection configuration to the protection system, and screen and mark safety information for basic protection; The buffer protection is locked by changes in the tag information and disconnects the faulty station from the network. Local delay protection is set with overvoltage step thresholds Va, Vb, Vc, and delay Tw; Rapid protection is implemented by controlling and activating the caller in areas with assigned numbers when other protections fail. S3: Establish a fault judgment delay loop based on the protection system: If the current voltage Vp < Va, continue monitoring; otherwise, enter the backup threshold judgment; in the backup threshold judgment, if Vp < Vb, reduce the voltage; if Vp < Vc, cut off the power supply to some equipment; otherwise, trip the circuit breaker.

2. The substation hierarchical protection configuration method according to claim 1, characterized in that, The hierarchical protection system includes a local layer, a station-level layer, and a wide-area layer.

3. The substation hierarchical protection configuration method according to claim 2, characterized in that, The hierarchical protection system includes four protection types: fast protection, basic protection, buffer protection, and local delay protection. The basic protection is the first layer of protection, the buffer protection is the second layer of protection, the local delay protection is the last layer of protection, and the rapid protection is the emergency mobilization protection.

4. The substation hierarchical protection configuration method according to claim 3, characterized in that, The fast protection is activated when basic protection, buffer protection, and local delay protection are not effective. The process includes: managing each substation by numbered zones; using the same fast protection dispatcher for substations within a range of n numbers; when a power grid fault occurs or a substation loses power in a zone, tripping measures are implemented for all substations in that zone, and all data transmission and reception channels except for the emergency information channel are cut off, and the processing results are uploaded to the monitoring platform.

5. The substation hierarchical protection configuration method according to claim 3, characterized in that, The basic protection is based on the wide area layer and the station area layer. It performs real-time filtering according to the type of information transmission and marks the safety information of the substation. Once a neighboring substation loses power or a power grid fault occurs, the marked information will change. Suspicious information is automatically transmitted to the monitoring platform. If the substation itself is found to be fault-free, this stage ends and the target substation and neighboring substations enter the buffer protection stage.

6. A substation hierarchical protection configuration method according to claim 3 or 5, characterized in that, The buffer protection is based on the wide-area layer. When a change in the marker information is detected, the monitoring platform will lock the target faulty substation according to the changed marker information, cut off the connection between the target substation and the adjacent substation, and enter the local time delay protection stage.

7. A substation hierarchical protection configuration method according to claim 6, characterized in that, The local delay protection establishes a fault judgment delay loop based on the station domain layer; The main process includes the pre-threshold judgment stage: setting overvoltage step thresholds and delay time Tw, the overvoltage step thresholds include three thresholds Va, Vb, and Vc; the monitoring platform sends a voltage monitoring signal to the target substation every Tw to determine whether the current voltage Vp is less than Va. If so, it continues to send voltage detection signals for three Tw and then releases the protection state; otherwise, it enters the backup threshold judgment stage.

8. A substation hierarchical protection configuration method according to claim 7, characterized in that, During the backup threshold judgment phase, the monitoring platform sends a voltage monitoring signal to the target substation every Tw to determine whether Vp is less than Vb. If so, it sends a step-down signal and a voltage detection signal to the target substation every Tw interval, and monitors in a loop until Vp <= Va. Otherwise, it determines whether Vp is less than Vc. If so, it cuts off the power supply to some important equipment every Tw interval; otherwise, it sends a trip signal to the target substation.

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