Low frequency protection action blocking fa method and device based on power distribution automation system

Abstract

The application discloses a low-frequency protection action blocking FA method and device based on a power distribution automation system, which adopts any one of a low-frequency alarm signal, a low-frequency protection action signal and a low-frequency setting scheme line comparison signal of a station terminal as a criterion for low-frequency protection action blocking FA; when any one of the signals is in an enabled state, the low-frequency protection action blocking FA is performed. The method provided by the application judges the low-frequency protection action blocking FA through three independent signals, introduces a low-frequency setting scheme line tripping signal comparison to prevent the low-frequency protection from malfunctioning and blocking the FA function. Through the fast blocking FA function, the application prevents the power supply to the tripped line from being re-performed due to the FA action, thereby damaging the system stability. The application pushes the protection action and blocking FA messages after the low-frequency low-voltage load shedding action, thereby ensuring that dispatchers can obtain power grid information in time.

Description

Technical Field

[0001] This invention belongs to the field of power distribution network protection technology, specifically, it relates to a method and device for blocking low-frequency protection actions (FA) based on a power distribution automation system. Background Technology

[0002] When a low-frequency load shedding action occurs in the power system, the low-voltage side outgoing lines of the main transformer sequentially disconnect 10kV or 20kV distribution lines in batches until the system frequency returns to normal. In this case, the distribution automation system detects the line protection action signal and the switch is opened, which meets the FA (Feeder Automation) start-up conditions. The FA function will be activated, and the line tie switch will be closed remotely to restore power to the lines that have been disconnected by the low-frequency protection. This causes the low-frequency load shedding action to lose its load shedding effect, affecting system stability and expanding the power outage area.

[0003] In existing technologies, the FA (Feature Assist) error prevention verification method for distribution master stations based on power grid operation data (CN108155717B) embeds the FA error prevention verification function module as an independent module into the distribution master station system to perform error prevention verification and safety interlocking on the FA execution scheme. However, the FA activation conditions in existing technologies are switch opening signals and protection action signals. That is, after the system receives the switch opening signal, it collects the system's protection action signal within 30 seconds. If a protection action signal is collected within 30 seconds, the FA will activate; or, after receiving the switch opening signal, the system collects the system's protection action signal and line opening signal within 30 seconds. If both the protection action signal and the line opening signal are collected within 30 seconds, the FA will activate. This results in the inability to achieve rapid FA interlocking, causing the FA to re-energize the disconnected line, thus compromising system stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and device for blocking low-frequency protection actions (FA) based on distribution automation systems, applicable to 10kV and 20kV power grids and distribution automation systems.

[0005] The present invention adopts the following technical solution.

[0006] This invention proposes a method for blocking low-frequency protection action (FA) based on a distribution automation system. The method uses any one of the following signals as the criterion for blocking low-frequency protection action (FA): low-frequency alarm signal from the station terminal, low-frequency protection action signal, and low-frequency setting scheme line comparison signal. When any one of the signals is in an enabled state, the low-frequency protection action (FA) is blocked.

[0007] Among them, determining the low-frequency protection action blocking FA based on the low-frequency alarm signal of the station terminal includes:

[0008] Step 1.1: Obtain the frequency of the station terminal;

[0009] Step 1.2: When the frequency of the station terminal is lower than the set low frequency threshold, an alarm signal is sent to the main station according to the terminal remote signaling point table.

[0010] Step 1.3: The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low-frequency alarm signal.

[0011] Step 1.4: When a low-frequency alarm signal is detected, the main station low-frequency protection action blocks FA.

[0012] Preferably, in step 1.2, the low-frequency threshold is set to 48Hz to 49.5Hz.

[0013] Preferably, the remote signaling point table of the master station and the remote signaling point table of the terminal are consistent.

[0014] Among them, determining the low-frequency protection action blocking FA based on the low-frequency protection action signal includes:

[0015] Step 2.1: Obtain the switch tripping signal;

[0016] Step 2.2: Obtain system protection action alarm signals within a preset time period;

[0017] Step 2.3: Obtain the low-frequency protection action signal;

[0018] Step 2.4: When the low-frequency protection action signal is in an enabled state, and the switch tripping signal is enabled and the system protection action alarm signal is enabled within a preset time period, then the low-frequency protection action blocks FA.

[0019] Preferably, in step 2.2, the preset time period is 30 seconds.

[0020] Among them, the method of determining the low-frequency protection action blocking FA based on the line comparison signal of the low-frequency setting scheme includes:

[0021] Step 3.1: Obtain the switch tripping signal;

[0022] Step 3.2: Obtain system protection action alarm signals and the number of tripped lines within a preset time period;

[0023] Step 3.3: If the switch tripping signal is enabled and the system protection action alarm signal is enabled within the preset time period, and when the number of tripping lines exceeds the first limit, compare all tripping lines with the load reduction cycle of the low-frequency setting scheme.

[0024] Step 3.4: When a number of lines exceeding the second limit are in the same low-frequency load reduction cycle comparison, the low-frequency protection will block FA.

[0025] Preferably, in step 3.2, the preset time period is 30 seconds.

[0026] Preferably, the first limit is not less than 4, the second limit is not less than 5, and the second limit is greater than the first limit.

[0027] Preferably, the load reduction cycle comparison refers to comparing the tripped lines with the under-frequency load reduction cycle table, and recording all lines in the load reduction cycle table according to the load reduction cycle.

[0028] Preferably, the master station initiates the low-frequency protection action to block the FA and pushes the FA blocking information to the dispatcher.

[0029] In another aspect, the present invention also proposes a low-frequency protection action blocking FA device based on a power distribution automation system, comprising: a first criterion module, a second criterion module, a third criterion module, and a low-frequency protection action blocking FA module.

[0030] The first criterion module is used to obtain the frequency of the station terminal. When the frequency of the station terminal is lower than the set low frequency threshold, it sends an alarm signal to the master station according to the terminal remote signaling point table. The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low frequency alarm signal. When it is determined to be a low frequency alarm signal, it sends a first enable signal to the low frequency protection action blocking FA module.

[0031] The second criterion module is used to acquire the switch opening signal, acquire the system protection action alarm signal within a preset time period, acquire the low-frequency protection action signal, and when the low-frequency protection action signal is in an enabled state, and the switch opening signal is enabled and the system protection action alarm signal within the preset time period is enabled, send a second enable signal to the low-frequency protection action blocking FA module.

[0032] The third criterion module is used to obtain the switch opening signal and obtain the number of opening lines within a preset time period. When the number of opening lines exceeds the first limit, it compares all the opening lines with the load reduction cycle of the low-frequency setting scheme. When there are lines in the same low-frequency load reduction cycle that exceed the second limit among all the opening lines, it sends a third enable signal to the low-frequency protection action blocking FA module.

[0033] The low-frequency protection action blocking FA module is used to activate the low-frequency protection action blocking FA when the first enable signal is high, the second enable signal is high, or the third enable signal is high.

[0034] The beneficial effects of this invention are as follows: Compared with the prior art, the method proposed in this invention uses three independent signals to determine the blocking of the FA (Automatic Facilitator) for low-frequency protection actions, and introduces a comparison of the line tripping signal in the low-frequency setting scheme to prevent the blocking of the FA function when the low-frequency protection malfunctions. By quickly blocking the FA function, it prevents the restoration of power to disconnected lines due to FA action, thus preventing disruption of system stability. Furthermore, this invention ensures that dispatchers receive timely grid information by pushing messages regarding protection actions and FA blocking after low-frequency, low-voltage load shedding. Attached Figure Description

[0035] Figure 1 This is a flowchart of a low-frequency protection action blocking FA method based on a power distribution automation system proposed in this invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0037] This invention proposes a method for blocking low-frequency protection actions (FA) based on a distribution automation system, such as... Figure 1 As shown, any one of the following signals from the station terminal—the low-frequency alarm signal, the low-frequency protection action signal, and the low-frequency setting scheme line comparison signal—is used as the criterion for blocking the low-frequency protection action FA; when any one signal is in the enabled state, the low-frequency protection action blocks the FA.

[0038] Among them, determining the low-frequency protection action blocking FA based on the low-frequency alarm signal of the station terminal includes:

[0039] Step 1.1: Obtain the frequency of the station terminal;

[0040] Step 1.2: When the frequency of the station terminal is lower than the set low frequency threshold, an alarm signal is sent to the main station according to the terminal remote signaling point table.

[0041] Preferably, in step 1.2, the low-frequency threshold is set to 48Hz to 49.5Hz.

[0042] Step 1.3: The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low-frequency alarm signal.

[0043] Preferably, the remote signaling point table of the master station and the remote signaling point table of the terminal are consistent.

[0044] Step 1.4: When a low-frequency alarm signal is detected, the main station low-frequency protection action blocks FA.

[0045] Among them, determining the low-frequency protection action blocking FA based on the low-frequency protection action signal includes:

[0046] Step 2.1: Obtain the switch tripping signal;

[0047] Step 2.2: Obtain system protection action alarm signals within a preset time period;

[0048] Preferably, in step 2.2, the preset time period is 30 seconds.

[0049] Step 2.3: Obtain the low-frequency protection action signal;

[0050] Step 2.4: When the low-frequency protection action signal is in an enabled state, and the switch tripping signal is enabled and the system protection action alarm signal is enabled within a preset time period, then the low-frequency protection action blocks FA.

[0051] Among them, the method of determining the low-frequency protection action blocking FA based on the line comparison signal of the low-frequency setting scheme includes:

[0052] Step 3.1: Obtain the switch tripping signal;

[0053] Step 3.2: Obtain system protection action alarm signals and the number of tripped lines within a preset time period;

[0054] Preferably, in step 3.2, the preset time period is 30 seconds.

[0055] Step 3.3: If the switch tripping signal is enabled and the system protection action alarm signal is enabled within the preset time period, and when the number of tripping lines exceeds the first limit, compare all tripping lines with the load reduction cycle of the low-frequency setting scheme.

[0056] Step 3.4: When a number of lines exceeding the second limit are in the same low-frequency load reduction cycle comparison, the low-frequency protection will block FA.

[0057] Preferably, the first limit is not less than 4, the second limit is not less than 5, and the second limit is greater than the first limit.

[0058] Preferably, the load reduction cycle comparison refers to comparing the tripped lines with the under-frequency load reduction cycle table, and recording all lines in the load reduction cycle table according to the load reduction cycle.

[0059] A typical under-frequency load shedding schedule is used to batch disconnect lines according to a certain frequency and delay. Taking the under-frequency load shedding schedule for the Wuxi area as an example, see the table below for details:

[0060]

[0061] Preferably, the master station initiates the low-frequency protection action to block the FA and pushes the FA blocking information to the dispatcher.

[0062] In another aspect, the present invention also proposes a low-frequency protection action blocking FA device based on a power distribution automation system, comprising: a first criterion module, a second criterion module, a third criterion module, and a low-frequency protection action blocking FA module.

[0063] The first criterion module is used to obtain the frequency of the station terminal. When the frequency of the station terminal is lower than the set low frequency threshold, it sends an alarm signal to the master station according to the terminal remote signaling point table. The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low frequency alarm signal. When it is determined to be a low frequency alarm signal, it sends a first enable signal to the low frequency protection action blocking FA module.

[0064] The second criterion module is used to acquire the switch opening signal, acquire the system protection action alarm signal within a preset time period, acquire the low-frequency protection action signal, and when the low-frequency protection action signal is in an enabled state, and the switch opening signal is enabled and the system protection action alarm signal within the preset time period is enabled, send a second enable signal to the low-frequency protection action blocking FA module.

[0065] The third criterion module is used to obtain the switch opening signal and obtain the number of opening lines within a preset time period. When the number of opening lines exceeds the first limit, it compares all the opening lines with the load reduction cycle of the low-frequency setting scheme. When there are lines in the same low-frequency load reduction cycle that exceed the second limit among all the opening lines, it sends a third enable signal to the low-frequency protection action blocking FA module.

[0066] The low-frequency protection action blocking FA module is used to activate the low-frequency protection action blocking FA when the first enable signal is high, the second enable signal is high, or the third enable signal is high.

[0067] This invention proposes a low-frequency protection action blocking FA (Feature Assist) device based on a distribution automation system. This device blocks the FA function of the distribution automation system when the power system experiences low-frequency load shedding protection action, preventing the FA action from re-energizing the disconnected lines and affecting system stability. When the system frequency decreases, the low-frequency protection action disconnects multiple lines in a set sequence. This module uses the activation of the system's low-frequency protection, the tripping of more than five lines, and the substation frequency being <48.5Hz as the criteria for blocking the FA function. When any of these conditions are met, the FA function is blocked, and low-frequency protection action and FA blocking information are pushed to the distribution automation system, ensuring that dispatchers receive information promptly, thus realizing the low-frequency protection FA function blocking module.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for blocking low-frequency protection actions (FA) based on a distribution automation system, characterized in that, The method uses any one of the following signals as the criterion for blocking the low-frequency protection action (FA): the low-frequency alarm signal from the station terminal, the low-frequency protection action signal, and the low-frequency setting scheme line comparison signal; when any one signal is enabled, the low-frequency protection action blocks the FA; the method of determining the low-frequency protection action blocking the FA based on the low-frequency setting scheme line comparison signal includes: Step 3.1: Obtain the switch tripping signal; Step 3.2: Obtain system protection action alarm signals and the number of tripped lines within a preset time period; Step 3.3: If the switch tripping signal is enabled and the system protection action alarm signal is enabled within the preset time period, and when the number of tripping lines exceeds the first limit, compare all tripping lines with the load reduction cycle of the low-frequency setting scheme. Step 3.4: When a number of lines exceeding the second limit are in the same low-frequency load reduction cycle comparison, the low-frequency protection will block FA.

2. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, In the method, determining the low-frequency protection action blocking FA based on the low-frequency alarm signal of the station terminal includes: Step 1.1: Obtain the frequency of the station terminal; Step 1.2: When the frequency of the station terminal is lower than the set low frequency threshold, an alarm signal is sent to the main station according to the terminal remote signaling point table. Step 1.3: The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low-frequency alarm signal. Step 1.4: When a low-frequency alarm signal is detected, the main station low-frequency protection action blocks FA.

3. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 2, characterized in that, In step 1.2, the low-frequency threshold is set to 48Hz~49.5Hz.

4. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 2, characterized in that, The remote signaling point table of the main station and the remote signaling point table of the terminal are consistent.

5. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, In the method, determining the low-frequency protection action blocking FA based on the low-frequency protection action signal includes: Step 2.1: Obtain the switch tripping signal; Step 2.2: Obtain system protection action alarm signals within a preset time period; Step 2.3: Obtain the low-frequency protection action signal; Step 2.4: When the low-frequency protection action signal is in an enabled state, and the switch tripping signal is enabled and the system protection action alarm signal is enabled within a preset time period, then the low-frequency protection action blocks FA.

6. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 5, characterized in that, In step 2.2, the preset time period is 30 seconds.

7. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, In step 3.2, the preset time period is 30 seconds.

8. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, The first limit is not less than 4, the second limit is not less than 5, and the second limit is greater than the first limit.

9. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, The load reduction cycle comparison refers to comparing the tripped lines with the under-frequency load reduction cycle table. All lines are recorded in the load reduction cycle table according to the load reduction cycle.

10. The low-frequency protection action blocking FA method based on a distribution automation system according to claim 1, characterized in that, The main station initiates low-frequency protection action to block the FA and pushes the FA blocking information to the dispatcher.

11. A low-frequency protection action blocking FA device based on a power distribution automation system, used to implement the method of any one of claims 1 to 10, characterized in that, The device includes: a first criterion module, a second criterion module, a third criterion module, and a low-frequency protection action blocking FA module; The first criterion module is used to obtain the frequency of the station terminal. When the frequency of the station terminal is lower than the set low frequency threshold, it sends an alarm signal to the master station according to the terminal remote signaling point table. The master station compares the received alarm signal with the master station remote signaling point table to determine whether it is a low frequency alarm signal. When it is determined to be a low frequency alarm signal, it sends a first enable signal to the low frequency protection action blocking FA module. The second criterion module is used to acquire the switch opening signal, acquire the system protection action alarm signal within a preset time period, acquire the low-frequency protection action signal, and when the low-frequency protection action signal is in an enabled state, and the switch opening signal is enabled and the system protection action alarm signal within the preset time period is enabled, send a second enable signal to the low-frequency protection action blocking FA module. The third criterion module is used to obtain the switch opening signal and obtain the number of opening lines within a preset time period. When the number of opening lines exceeds the first limit, it compares all the opening lines with the load reduction cycle of the low-frequency setting scheme. When there are lines in the same low-frequency load reduction cycle that exceed the second limit among all the opening lines, it sends a third enable signal to the low-frequency protection action blocking FA module. The low-frequency protection action blocking FA module is used to activate the low-frequency protection action blocking FA when the first enable signal is high, the second enable signal is high, or the third enable signal is high.

Images