Three - line defense structure of power system based on breaker failure protection backup

Abstract

The present invention discloses a three - line defense structure of a power system based on the backup of breaker failure protection, which includes a failure protection device, relay protection, a stability control system, and an out - of - step splitting system. The relay protection, the stability control system, and the out - of - step splitting system are all connected to the failure protection device, and the failure protection device is connected to the breaker and is used to trip the element or line. When any one of the relay protection, the stability control system, and the out - of - step splitting system issues a breaker tripping signal, if the breaker successfully trips, the protection is successful; if the breaker opening fails, an enabling failure signal is output to start the failure protection. The failure protection device cuts off all other elements or lines connected to the bus of the element, indirectly achieving the opening.

Description

Technical Field

[0001] The invention belongs to the field of power system operation control, and in particular relates to a three-line defense structure of a power system based on circuit breaker failure protection backup. Background Art

[0002] As the scale of the power grid system continues to expand, whether the power system can maintain stability and whether it can enter a new stable state after disturbances of varying sizes is particularly important for the safe and reliable operation of the power system. Large-scale power grids, especially high-proportion new energy AC / DC hybrid power grids with ultra-high voltage direct current and large-scale new energy access, have gradually become the development trend of large power grids, and their safety and stability are particularly important.

[0003] In the current secondary system and three-line defense configuration, relay protection, stabilization control system and out-of-step separation are configured separately, independently and without affecting each other. This configuration method and means ensures the reliable operation of the three-line defense and the safety and stability of the power system to a certain extent. Long-term operation practice has also verified this.

[0004] However, the current three-line configuration only considers the normal operation of the system, including primary equipment and secondary systems, communication circuits, etc., and does not consider the control failure caused by switch failure. Since the relay protection system mainly serves the scope of the protected components, its impact is relatively small, and because it has been widely concerned for a long time, its backup system is relatively complete. However, in the second and third lines of defense among the three lines of defense, because their probability of action is extremely small, and they are both low-probability events, but once they are started, if their control effect does not meet expectations, it will cause extremely serious consequences, and even the collapse of the entire system. It is precisely because of its low probability of action that the long-term configuration does not consider the backup factor. During the debugging of some stabilization control systems, it has occurred that the stabilization control system failed to cut off the load due to circuit breaker failure, resulting in insufficient cutting volume, affecting the recovery of system stability. If a similar incident occurs in actual operation, according to the existing configuration, the control target will not be achieved, resulting in continuous system instability or even system collapse, causing great economic losses.

[0005] The three lines of defense, including the original relay protection, stabilization control system, and out-of-step disconnection, work together over time and serve as backups for the previous lines to a certain extent. When the stabilization control system fails to cut the machine and load, the system instability continues and continues to deteriorate, which will trigger the third line of defense, that is, out-of-step disconnection, to achieve emergency control by disconnecting the power grid. This situation worsens the operating environment of the power system, squeezes the control space, and prolongs the abnormal operation time of the power system. It is uneconomical, unreliable, and unacceptable. When the system disconnection fails, the system will continue to deteriorate, leading to the risk of system collapse, resulting in extremely serious consequences. Summary of the invention

[0006] To address the deficiencies in the existing technology, the objective of the present invention is to provide a three - line defense structure for a power system based on the backup of breaker failure protection. In the starting failure signal circuit of the relay protection, the signals of the stability control system and the out - of - step splitting are connected in parallel. The failure protection in the original relay protection is separated and used as the common backup for the three - line defenses of relay protection, stability control system, and out - of - step splitting.

[0007] The present invention adopts the following technical solutions.

[0008] A three - line defense structure for a power system based on the backup of breaker failure protection. The three - line defense structure of the power system includes a failure protection device, relay protection, a stability control system, and an out - of - step splitting system. The relevant devices of the three - line defenses of relay protection, stability control system, and out - of - step splitting are all connected to the failure protection device. The failure protection device is connected to the breaker and is used to trip the element or line.

[0009] When any one of the relay protection, stability control system, and out - of - step splitting system issues a breaker tripping signal, if the breaker successfully trips, the protection is successful; if the breaker opening fails, an enabling failure signal is output, which will activate the failure protection. The failure protection device will cut off all other elements or lines connected to the bus of the element, indirectly achieving the opening.

[0010] Further, the failure protection device includes an OR gate, an enabling failure signal circuit, and a comprehensive judgment circuit. The comprehensive judgment circuit comprehensively judges according to the enabling failure signal, breaker position, and whether there is current in the breaker, and outputs an action signal to the adjacent breaker to trip the adjacent breaker.

[0011] Further, the failure protection device includes an OR gate, an enabling failure signal circuit, and a comprehensive judgment circuit. The comprehensive judgment circuit comprehensively judges according to the enabling failure signal, breaker position, and whether there is current in the breaker, and performs an operation of delaying the trial - tripping of the failed breaker. If successful, the breaker is disconnected; otherwise, the adjacent breaker is tripped.

[0012] Further, the breaker current signal is obtained from the relay protection device, and the breaker position signal is obtained from the relay protection device or the corresponding breaker intelligent terminal, constituting the breaker current signal and position signal in the breaker failure protection criterion.

[0013] Further, when the breaker position is open, it is at a high level and regarded as valid; otherwise, it is at a low level and regarded as invalid. When there is current in the breaker, it is at a high level and regarded as valid; when there is no current in the breaker, it is at a low level and regarded as invalid.

[0014] The breaker failure protection operation process of the three - line defense structure for a power system based on the backup of breaker failure protection includes the steps:

[0015] Step 1: The breaker trip signals of the relay protection, stability control system, and out-of-step splitting system are sent out in their respective output circuits, and at the same time, the breaker trip signals are sent to the malfunction protection device.

[0016] Step 2: If any of the relay protection, stability control system, and out-of-step splitting system fails to open, an enabling malfunction signal is output. The signal output through the OR gate is connected to the enabling malfunction signal port of the malfunction protection device.

[0017] Step 3: The breaker current signal is collected from the relay protection device, and the breaker position signal is collected from the relay protection device or the corresponding breaker intelligent terminal, constituting the breaker current signal and position signal in the breaker malfunction protection criterion.

[0018] Step 4: The breaker malfunction protection issues an action signal to the adjacent breaker and trips the adjacent breaker only when the enabling malfunction signal, breaker position signal, and breaker current signal are all valid.

[0019] Further, in Step 2, the enabling malfunction signal is valid at a high level and invalid at a low level.

[0020] Further, in Step 4, the breaker malfunction protection issues an action signal and performs a time-delay test trip operation on the malfunctioning breaker only when the enabling malfunction signal, breaker position signal, and breaker current signal are all valid. If successful, the breaker is disconnected; otherwise, the breaker malfunction protection issues an action signal to the adjacent breaker and trips the adjacent breaker.

[0021] Further, in Step 1, for a conventional substation, the secondary circuit wiring needs to be modified, and a signal is led out from the output circuit to the breaker malfunction protection device panel.

[0022] For an intelligent substation, virtual terminals and connections need to be added in the SCD file, and the action signal is connected to the breaker malfunction protection device.

[0023] The beneficial effects of the present invention are as follows. Compared with the prior art, the present invention is based on the three-line defense structure of the power system with breaker malfunction protection as the backup, improves the operation effect of the three-line defense of the power system, perfects the operation mechanism of the three-line defense, and optimizes the control effect of the three-line defense.

[0024] Based on the three-line defense structure of the power system with breaker malfunction protection as the backup, on the one hand, the present invention still maintains the independence of the relay protection, stability control system, and out-of-step splitting system; on the other hand, through reclassification, the breaker malfunction protection is used as a common backup measure for the three-line defense, realizing the functions of the relay protection to cut off the fault, the stability control system to cut off the generator and load, and the out-of-step splitting system to split the large system in case of switch malfunction.

[0025] The three - line defense structure of the power system of the present invention consists of a first line of defense composed of relay protection devices, a second line of defense composed of safety and stability control devices, etc., a third line of defense composed of out - of - step splitting devices, etc., and a backup line of defense composed of breaker failure protection. The backup line of defense serves as a common backup for the first, second, and third lines of defense to compensate for the opening failure caused by problems such as breaker mechanism failures and the insufficient amount of cut - off resulting therefrom.

[0026] The structure proposed by the present invention can effectively prevent the weakening of control effect, the continuous instability of the system, and the damage of the system caused by insufficient cut - off amount, compensate the control effect, complete the control task as soon as possible, and return the power system to the normal operation state. At the same time, it does not affect the basic principles of the original three lines of defense being independent and uncorrelated with each other, ensuring the normal and stable operation of the original three lines of defense. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 FIG. is a schematic diagram of the three - line defense structure of the power system based on breaker failure protection backup according to the present invention;

[0028] Figure 2 FIG. is a schematic diagram of the secondary circuit applied to the three - line defense structure of the power system based on breaker failure protection backup according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The following further describes the present application with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present application.

[0030] The present invention introduces breaker failure protection as a backup measure for the three - line defense of the power system, separates the breaker failure protection, and uses it as a backup measure for the overall system of the power system's stable and safe defense system.

[0031] As Figure 1 shown, the three - line defense structure of the power system based on breaker failure protection backup according to the present invention includes a breaker failure protection device, relay protection, a stability control system, and an out - of - step splitting system. The relay protection, the stability control system, and the out - of - step splitting system are all connected to the breaker failure protection device, and the breaker failure protection device is connected to the breaker for tripping elements, lines, etc.

[0032] When any one of the relay protection, the stability control system, and the out - of - step splitting system issues a breaker tripping signal, if the breaker is successfully tripped, the protection is successful; if an opening failure occurs, an enabling breaker failure signal is output, which will start the breaker failure protection, and the breaker failure protection device will cut off all other elements or lines connected to the bus of the element, indirectly realizing the opening.

[0033] Based on the characteristics of the existing three lines of defense in the power system, the present invention proposes a "3 + 1" power system security and stability defense line architecture. The malfunction protection in the original relay protection is separated and used as the common backup for the three lines of defense, namely relay protection, stability control system, and out-of-step splitting. When any one of the three systems fails to open due to breaker malfunction when opening components, lines, etc., the malfunction protection will be activated, and all other components or lines connected to the bus of the component will be cut off through the malfunction protection, indirectly achieving the opening.

[0034] The present invention uses the breaker malfunction protection as the backup for the first, second, and third lines of defense in the power system, such as relay protection, stability control system, and system splitting, serving as the backup means for operations such as relay protection, system security and stability control, and system splitting, improving the control effect and success rate.

[0035] As Figure 2 shown, for the secondary circuit applied in the three-line defense structure of the power system based on the breaker malfunction protection backup described in the present invention, the malfunction protection device includes a multi-channel signal receiving device (OR gate), a malfunction activation signal circuit, and a comprehensive judgment circuit. The comprehensive judgment circuit comprehensively judges based on the malfunction activation signal, breaker position, and whether there is current in the breaker, and performs an operation to try to trip the malfunctioning breaker with a delay of 10 ms. If successful, the breaker is disconnected; otherwise, the adjacent breaker is tripped to complete the cutting of the line.

[0036] The malfunction activation signals of the relay protection, stability control system, and out-of-step splitting system are all connected to the malfunction activation signal circuit through the multi-channel signal receiving device.

[0037] Therefore, during the transformation of the original device, only a minor transformation of the secondary circuit is required, with a small workload, easy to implement, strong popularization, and considerable economic benefits.

[0038] The present invention uses the breaker malfunction protection as the backup means for the three lines of defense, and the action sequence is after each line of defense. By directly controlling the associated breaker, it compensates for the impact brought by the failure of excision.

[0039] The working process of the three-line defense structure of the power system based on the breaker malfunction protection backup described in the present invention:

[0040] Step 1, in addition to being sent out in their respective output circuits, the breaker trip signals of the power system security defense devices such as the relay protection, stability control system, and out-of-step splitting system are also sent to the malfunction protection device simultaneously.

[0041] The three-line defense devices such as the relay protection, stability control system, and out-of-step splitting system not only need to send action signals to the corresponding breaker through their respective output circuits but also send signals to the malfunction protection device simultaneously to activate the backup protection excision function of the breaker malfunction protection.

[0042] During this process, for a conventional substation, it is necessary to modify the secondary circuit wiring and lead a signal from the trip output circuit to the breaker failure protection device cubicle. During this process, for an intelligent substation, it is necessary to add virtual terminals and connections in the SCD file and connect the action signal to the breaker failure protection device.

[0043] The present invention improves the existing power system security defense structure mainly based on three lines of defense. In its specific implementation process, no modification is made to the breaker failure protection device itself. The improvement work focuses on the transformation of the secondary circuit in a conventional substation and the modification of the SCD file in an intelligent substation.

[0044] Step 2: When the three lines of defense devices such as the relay protection, stability control system, and out-of-step splitting system experience a breaking failure, they output a start failure signal. The signal is output through an "OR" gate and connected to the start failure signal port of the failure protection device, serving as the source of the start failure signal in the failure protection logic. A high level is valid, and a low level is invalid.

[0045] Since the breaker failure protection serves as the common backup for the three lines of defense, the related devices of any one of the three lines of defense should be able to activate the backup protection function of the breaker failure protection. Therefore, the action signals of the related devices of the three lines of defense are output through an "OR" gate to form a breaker start failure signal, which activates the breaker failure protection. When there is an action signal from the three devices, the output action signal is at a high level; when there is no action signal, it remains at a low level. Therefore, the synthesized start failure signal should be valid at a high level and invalid at a low level.

[0046] Step 3: The breaker current signal for the failure protection is obtained from the relay protection device, and the breaker position signal is obtained from the relay protection device or the corresponding breaker intelligent terminal, constituting the breaker current signal and position signal in the breaker failure protection criterion. For these two signals, when the breaker position is open, it is at a high level and regarded as valid; otherwise, it is at a low level and regarded as invalid. When there is current in the breaker, it is at a high level and regarded as valid; when there is no current in the breaker, it is at a low level and regarded as invalid.

[0047] The other two signals in the breaker failure protection criterion follow the original breaker failure protection configuration and are obtained through the relay protection or intelligent terminal. These two signals also follow the original breaker failure protection configuration, with a high level being valid and a low level being invalid.

[0048] Step 4: The breaker failure protection issues an action signal to the adjacent breaker to trip the breaker only when the start failure signal, breaker position signal, and breaker current signal are all valid.

[0049] Alternatively, the breaker failure protection issues an operation signal only when the enabling failure signal, breaker position signal, and breaker current signal are all valid. It then performs an operation to try tripping the failed breaker with a 10-ms delay. If successful, the breaker is disconnected; otherwise, the breaker failure protection issues an operation signal to the adjacent breaker to trip it and complete the disconnection of the line.

[0050] The breaker failure protection determines whether to trip adjacent breakers in cascade according to the original breaker failure protection criterion and decides whether to issue a signal. The action conditions are that one of the devices related to the three lines of defense issues an action signal, the breaker position is in the open position, and there is current flowing through the breaker, and adjacent breakers are tripped in cascade.

[0051] The beneficial effects of the present invention are as follows. Compared with the prior art, the present invention is based on the structure of the three lines of defense of the power system with breaker failure protection as the backup, improving the operation effect of the three lines of defense of the power system, perfecting the operation mechanism of the three lines of defense, and optimizing the control effect of the three lines of defense.

[0052] Based on the structure of the three lines of defense of the power system with breaker failure protection as the backup, on the one hand, the present invention still maintains the mutual independence of the relay protection, stability control system, and out-of-step splitting system; on the other hand, through reclassification, the breaker failure protection is used as the common backup measure for the three lines of defense, enabling the functions of the relay protection to cut off the fault, the stability control system to shed load and generators, and the out-of-step splitting system to split the large system to be completed even in case of breaker failure.

[0053] The structure of the three lines of defense of the power system of the present invention consists of the first line of defense composed of relay protection devices, the second line of defense composed of safety and stability control devices, etc., the third line of defense composed of splitting devices, etc., and the backup line of defense composed of breaker failure protection. The backup line of defense serves as the common backup for the first, second, and third lines of defense to compensate for the opening failure caused by problems such as breaker mechanism failures and the resulting insufficient cut-off amount.

[0054] The structure proposed by the present invention can effectively prevent the weakening of the control effect, the continuous instability of the system, and the damage to the system caused by insufficient cut-off amount, compensate the control effect, complete the control task as soon as possible, and return the power system to the normal operation state. At the same time, it does not affect the basic principles of the mutual independence and non-correlation of the original three lines of defense, ensuring the normal and stable operation of the original three lines of defense.

[0055] The applicant of the present invention has made a detailed description and illustration of the embodiments of the present invention with reference to the accompanying drawings. However, those skilled in the art should understand that the above embodiments are only the preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, rather than a limitation on the protection scope of the present invention. On the contrary, any improvement or modification made based on the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A three - line defense structure of a power system based on the backup of breaker failure protection, characterized in that, the three - line defense structure of the power system includes a failure protection device, relay protection, a stability control system, and an out - of - step splitting system. The devices related to the three - line defenses of relay protection, stability control system, and out - of - step splitting system are all connected to the failure protection device. The failure protection device is connected to the breaker and is used to trip the component or line; when any one of the relay protection, stability control system, and out - of - step splitting system issues a breaker tripping signal, if the breaker successfully trips, the protection is successful. If the breaker opening fails, an enabling failure signal is output, and the failure protection will be started. The failure protection device cuts off all other components or lines connected to the bus of the component, indirectly realizing the opening.

2. The three - line defense structure of a power system based on the backup of breaker failure protection according to claim 1, characterized in that, the failure protection device includes an OR gate, an enabling failure signal circuit, and a comprehensive judgment circuit. The comprehensive judgment circuit comprehensively judges according to the enabling failure signal, breaker position, and whether the breaker has current, and outputs an action signal to the adjacent breaker to trip the adjacent breaker.

3. The three - line defense structure of a power system based on the backup of breaker failure protection according to claim 1, characterized in that, the failure protection device includes an OR gate, an enabling failure signal circuit, and a comprehensive judgment circuit. The comprehensive judgment circuit comprehensively judges according to the enabling failure signal, breaker position, and whether the breaker has current, and performs an operation of delaying the trial - tripping of the failed breaker. If successful, the breaker is disconnected. Otherwise, the adjacent breaker is tripped.

4. The three - line defense structure of a power system based on the backup of breaker failure protection according to claim 2 or 3, characterized in that, the breaker current signal is collected from the relay protection device, and the breaker position signal is collected from the relay protection device or the corresponding breaker intelligent terminal, constituting the breaker current signal and position signal in the breaker failure protection criterion.

5. The three - line defense structure of a power system based on the backup of breaker failure protection according to claim 4, characterized in that, when the breaker position is open, it is at a high level and regarded as valid. Otherwise, it is at a low level and regarded as invalid. When the breaker has current, it is at a high level and regarded as valid. When the breaker has no current, it is at a low level and regarded as invalid.

6. The breaker failure protection action process of the three - line defense structure of a power system based on the backup of breaker failure protection according to any one of claims 1 - 5, characterized in that, it includes the steps: Step 1, the breaker tripping signals of the relay protection, stability control system, and out - of - step splitting system are issued in their respective output circuits, and at the same time, the breaker tripping signals are sent to the failure protection device; Step 2, when any one of the relay protection, stability control system, and out - of - step splitting system fails to open, an enabling failure signal is output, and the signal output through the OR gate is connected to the enabling failure signal port of the failure protection device; Step 3, the breaker current signal is collected from the relay protection device, and the breaker position signal is collected from the relay protection device or the corresponding breaker intelligent terminal, constituting the breaker current signal and position signal in the breaker failure protection criterion; Step 4: The breaker failure protection issues an operation signal to the adjacent breaker and trips the adjacent breaker only when the breaker failure start signal, breaker position signal, and breaker current signal are all valid.

7. The breaker failure protection operation process of the three - line defense structure of the power system based on breaker failure protection backup according to claim 6, characterized in that, In step 2, for the breaker failure start signal, a high level is valid and a low level is invalid.

8. The breaker failure protection operation process of the three - line defense structure of the power system based on breaker failure protection backup according to claim 6, characterized in that, In step 4, the breaker failure protection issues an operation signal only when the breaker failure start signal, breaker position signal, and breaker current signal are all valid, and performs an operation of delaying and tripping the failed breaker. If successful, the breaker is disconnected; otherwise, the breaker failure protection issues an operation signal to the adjacent breaker and trips the adjacent breaker.

9. The breaker failure protection operation process of the three - line defense structure of the power system based on breaker failure protection backup according to claim 6, characterized in that, In step 1, for a conventional substation, it is necessary to modify the secondary circuit wiring and lead a signal from the output circuit to the breaker failure protection device cabinet; For an intelligent substation, it is necessary to add virtual terminals and connections in the SCD file and connect the operation signal to the breaker failure protection device.

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