A method and device for closing the loop of a distribution line without power interruption for relay protection

Abstract

The present invention discloses a method and device for closing-loop relay protection of a distribution line without power interruption. The method includes the steps of: S1, obtaining the short-circuit current distribution characteristics and voltage characteristics of the closing-loop line; S2, designing the closing-loop device protection logic for the phase-shifting transformer according to the obtained short-circuit current distribution characteristics and voltage characteristics; S3, performing short-circuit protection on the distribution line during the closing-loop operation according to the configured closing-loop device protection logic. The present invention solves the problem that the original protection setting value of the distribution line cannot adapt to the change of current distribution during the closing-loop process, resulting in protection misoperation or refusal to operate, and the need to adjust the protection setting value. It ensures the safety and reliability of the closing-loop operation, and reduces the complexity and workload of the closing-loop operation.

Description

Technical Field

[0001] The present invention relates to the technical field of power system operation, and particularly to a method and device for non-stop power supply loop closing relay protection of a distribution line. Background Art

[0002] The distribution network is directly connected to the load and is the key to ensuring the power supply quality of users. It usually follows the basic principles of closed-loop design and open-loop operation. If it is possible to realize load transfer without power interruption, that is, non-stop power supply loop closing operation, the reliability of the operation of the distribution system can be greatly improved. The loop closing operation of the distribution line refers to the operation of closing the network composed of the distribution line, transformer or circuit breaker in the electrical operation of the power system. In case of faults, overloaded loads, power outages for maintenance, etc., the loop closing operation is carried out in the way of first closing and then breaking, which can realize load transfer and thus avoid power outages for users. Due to factors such as continuous adjustment of the power grid structure, imperfect protection configuration and design, etc., when the distribution network is looped, a large loop closing current may be generated, which may cause misoperation of the line protection. And after loop closing, the existing line protection cannot accurately distinguish the short circuit of the local line and the short circuit of the opposite line. In case of a short circuit on any side line, the protection of both lines will act simultaneously to trip, resulting in an enlarged fault influence range. At present, the commonly adopted solution is to install current protection on the tie switch and modify the protection settings of the two lines, and cooperate with the protection at the tie switch through time delay. Although this method can solve the problem of fault location, it prolongs the fault clearing time, and the protection settings need to be modified, the operation is cumbersome, and the probability of human operation error is increased. In addition, when a single-phase grounding fault occurs on one of the lines, since the 10 kV distribution network can operate with faults, the outgoing line switch does not trip. If the loop closing operation is carried out at this time, it will not only cause the spread of the fault, but also increase the difficulty of single-phase grounding and ranging of the distribution network.

[0003] Therefore, the conventional protection adopted by the existing distribution lines cannot meet the requirements of protection selectivity, quick action and reliability when protecting the distribution lines with loop closing operation, and the operation is cumbersome and cannot meet the requirements of fast and flexible actual operation of the distribution network. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a method and device for non-stop power supply loop closing relay protection of a distribution line, which realizes that the current protection of the distribution line can meet the requirements of protection selectivity and quick action in the loop closing state and can accurately monitor and locate single-phase grounding faults.

[0005] Technical Solution: A method for non-stop power supply loop closing relay protection of a distribution line includes the steps of:

[0006] S1, obtaining the short-circuit current distribution characteristics and voltage characteristics of the loop closing line;

[0007] S2. Design the protection logic for the loop closing device of the phase-shifting transformer according to the obtained short-circuit current distribution characteristics and voltage characteristics.

[0008] S3. Conduct short-circuit protection for the distribution line during the loop closing operation according to the configured protection logic.

[0009] Furthermore, by configuring current detection elements, zero-sequence voltage and low-voltage detection elements in the breaker circuits on both sides of the phase-shifting transformer in the loop closing device, detect the current characteristics, three-phase voltage and zero-sequence voltage characteristics of the loop closing lines on both sides.

[0010] Furthermore, configure instantaneous trip protection, overcurrent protection, single-phase grounding protection based on zero-sequence voltage start, and low-voltage protection for the breakers on both sides of the phase-shifting transformer in the loop closing device. The protection logic for the loop closing device of the phase-shifting transformer is as follows:

[0011] Before the loop closing operation, if the single-phase grounding protection or low-voltage protection of any one side of the breakers on both sides is activated, the loop closing operation should be terminated.

[0012] When a short circuit occurs in the line on the left side of the loop closing switch, the current protection of the left distribution line operates, the current protection at the breaker on the left side of the phase-shifting transformer operates, the left distribution line is disconnected, and the protection of the outgoing line switch of the right loop closing line does not operate; when a short circuit occurs in the line on the right side of the loop closing switch, the current protection of the right distribution line operates, the current protection at the breaker on the right side of the phase-shifting transformer operates, the right distribution line is disconnected, and the protection of the outgoing line switch of the left loop closing line does not operate.

[0013] When a single-phase grounding occurs in the line on the left side of the loop closing switch, the single-phase grounding protection of the zero-sequence voltage on the left side of the phase-shifting transformer operates, sends an alarm signal for the left single-phase grounding fault, and trips the breaker on the left side of the phase-shifting transformer. The protection of the outgoing line switch of the right loop closing line does not operate; when a single-phase grounding occurs in the line on the right side of the loop closing switch, the single-phase grounding protection of the zero-sequence voltage on the right side of the phase-shifting transformer operates, sends an alarm signal for the right single-phase grounding fault, and trips the breaker on the right side of the phase-shifting transformer. The protection of the outgoing line switch of the left loop closing line does not operate.

[0014] Furthermore, the operating value of the current protection of the breaker on the left side of the phase-shifting transformer is set according to the short-circuit current flowing through the left breaker at the outlet on the right side of the phase-shifting transformer during line loop closing; the operating value of the current protection of the breaker on the right side of the phase-shifting transformer in the loop closing device is set according to the short-circuit current flowing through the right breaker at the outlet on the left side of the phase-shifting transformer during line loop closing.

[0015] Furthermore, configure a tripping acceleration logic for the breakers on both sides of the phase-shifting transformer. When a short circuit or single-phase grounding occurs in one side of the line, if the breakers on both sides of the phase-shifting transformer are in the closed state, the breaker adjustment acceleration circuit is connected, and the breaker trips quickly.

[0016] Further, when performing a loop closing operation on a distribution line, based on the short-circuit current distribution characteristics and zero-sequence voltage and low-voltage characteristics, design the relay protection action logic and the setting values of each protection action for the loop closing device of the phase-shifting transformer:

[0017] When a short circuit occurs on the left line after loop closing, the distribution characteristic of the short-circuit current in the loop closing line is that the outgoing line breaker on the left line and the left breaker of the phase-shifting transformer of the loop closing device flow through the same larger short-circuit current, and the outgoing line breaker on the right line and the right breaker of the phase-shifting transformer of the loop closing device flow through the same smaller short-circuit current. The instantaneous trip protection setting value of the right breaker of the phase-shifting transformer is less than the instantaneous trip protection action value of the outgoing line breaker on the right line. The overcurrent protection on the left line and the current protection on the loop closing device act, and under the action of the acceleration logic, the breaker in the loop closing device accelerates to trip, cutting off the fault and locking the loop closing device. Since the fault on the right line has been cut off, the overcurrent protection returns without tripping;

[0018] When a single-phase grounding fault occurs on the left line after loop closing, the distribution characteristic of the zero-sequence voltage in the loop closing line is that zero-sequence voltage is detected on the left side of the phase-shifting transformer, and no zero-sequence voltage is detected on the right side of the phase-shifting transformer. At this time, the single-phase grounding protection in the loop closing device acts and issues an alarm signal indicating a single-phase grounding on the left line;

[0019] When a short circuit occurs on the left line before loop closing, the low-voltage characteristic in the loop closing line is that low voltage is detected on the left side of the phase-shifting transformer. At this time, the low-voltage protection in the loop closing device acts to lock the closing device;

[0020] When a single-phase grounding fault occurs on the left line before loop closing, the distribution characteristic of the zero-sequence voltage in the loop closing line is that zero-sequence voltage is detected on the left side of the phase-shifting transformer. At this time, the single-phase grounding protection based on zero-sequence voltage start in the loop closing device acts to lock the closing device.

[0021] A relay protection device for loop closing without power interruption of a distribution line, which is used to execute the above-mentioned relay protection method for loop closing without power interruption of a distribution line, includes:

[0022] An acquisition module, which is used to acquire the short-circuit current distribution characteristics and voltage characteristics of the loop closing line before and after loop closing;

[0023] A setting module, connected to the acquisition module, which is used to configure the action logic of the current protection, single-phase grounding protection and low-voltage protection on the breakers on both sides of the loop closing device;

[0024] A protection module, connected to the setting module, which is used to protect the loop closing line according to the configured protection logic;

[0025] The closing locking circuit is used to detect short circuits or single-phase grounding on any side of the line before and after the loop closing operation, and lock the loop closing device; after loop closing, if there is a short circuit or single-phase grounding on any side of the line, after accelerating the tripping of the circuit breakers on both sides of the phase-shifting transformer in the loop closing device, the loop closing device is locked.

[0026] Compared with the prior art, the remarkable effects of the present invention are as follows:

[0027] By configuring current detection elements, zero-sequence voltage and low-voltage detection elements in the circuit breakers on both sides of the phase-shifting transformer in the loop closing device, the present invention detects the current characteristics, three-phase voltage and zero-sequence voltage characteristics of the loop closing lines on both sides, and designs the protection logic of the loop closing device for the phase-shifting transformer according to the obtained short-circuit current distribution characteristics and voltage characteristics; when protecting the loop closing lines, it can accurately judge on which side the fault occurs, avoiding the expansion of the power outage range caused by the tripping of both lines. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of the protection method of the present invention;

[0029] Figure 2 It is a schematic diagram of the loop closing device;

[0030] Figure 3 It is a schematic diagram of the protection device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be further described in detail below in conjunction with the drawings in the specification and the specific embodiments.

[0032] As Figure 1 shown, it is a flow chart of the power-off-free loop closing relay protection method of the present invention, including the following steps:

[0033] Step 1, obtain the short-circuit current distribution characteristics, low-voltage and zero-sequence voltage characteristics of the loop closing lines;

[0034] In the loop closing device, current detection elements, zero-sequence voltage and low-voltage detection elements are configured in the circuit breakers on both sides of the phase-shifting transformer to detect the current characteristics, three-phase voltage and zero-sequence voltage characteristics of the loop closing lines on both sides.

[0035] Step 2, design the protection logic of the loop closing device for the phase-shifting transformer according to the obtained short-circuit current distribution characteristics and voltage characteristics;

[0036] In the loop closing device, instantaneous overcurrent protection and overcurrent protection are configured for the circuit breakers on both sides of the phase-shifting transformer. As Figure 2As shown in the figure, when the left - hand side line has a short - circuit, the current protection of the left - hand side distribution line operates, the current protection at the left - hand side breaker of the phase - shifting transformer operates, the left - hand side distribution line is disconnected, and the protection of the outgoing line switch of the right - hand side closed - loop line does not operate; when the right - hand side line of the closed - loop switch has a short - circuit, the current protection of the right - hand side distribution line operates, the current protection at the right - hand side breaker of the phase - shifting transformer operates, the right - hand side distribution line is disconnected, and the protection of the outgoing line switch of the left - hand side closed - loop line does not operate.

[0037] In the closed - loop device, single - phase grounding protection based on zero - sequence voltage startup is configured for the breakers on both sides of the phase - shifting transformer. As Figure 2 shown in the figure, when a single - phase grounding occurs on the left - hand side line, the single - phase grounding protection of the zero - sequence voltage on the left - hand side of the phase - shifting transformer operates, sending an alarm signal for the left - hand side single - phase grounding fault, tripping the left - hand side breaker of the phase - shifting transformer, and the protection of the outgoing line switch of the right - hand side closed - loop line does not operate; when a single - phase grounding occurs on the right - hand side line of the closed - loop switch, the single - phase grounding protection of the zero - sequence voltage on the right - hand side of the phase - shifting transformer operates, sending an alarm signal for the right - hand side single - phase grounding fault, tripping the right - hand side breaker of the phase - shifting transformer, and the protection of the outgoing line switch of the left - hand side closed - loop line does not operate.

[0038] In the closed - loop device, a tripping acceleration logic is configured for the breakers on both sides of the phase - shifting transformer. As Figure 2 shown in the figure, when a short - circuit or single - phase grounding occurs on one side line, if the breakers on both sides of the phase - shifting transformer are in the closed state, the breaker adjustment acceleration circuit is turned on, and the breaker trips quickly.

[0039] In the closed - loop device, a closing - locking circuit is set for the breakers on both sides of the phase - shifting transformer. As Figure 2 shown in the figure, it is used to detect the existence of a short - circuit or single - phase grounding on any one - side line before and after the closed - loop operation to lock the closed - loop device. Before closing the loop, if there is a short - circuit or single - phase grounding on any one - side line, the closed - loop device is locked; after closing the loop, if there is a short - circuit or single - phase grounding on any one - side line, after quickly tripping the breakers on both sides of the phase - shifting transformer in the closed - loop device, the closed - loop device is locked.

[0040] Step 3: According to the configured protection logic, perform short - circuit protection on the distribution line during the closed - loop operation.

[0041] According to the short - circuit current distribution characteristics, low - voltage characteristics, and zero - sequence voltage characteristics of the closed - loop line, design the relay protection action logic for the phase - shifting transformer closed - loop device; and according to the optimized protection action logic and setting values, perform relay protection on the closed - loop line, achieving accurate judgment of the faulty line and rapid isolation of the fault without modifying the original line protection setting values. At the same time, when a fault is found on the line before and after closing the loop, the closed - loop device is locked in time to avoid closing onto the faulty line, solving the problem that when using traditional current protection to protect the closed - loop line, it cannot accurately judge on which side the fault occurs, resulting in both sides of the line tripping and expanding the power outage range.

[0042] When a loop closing operation is performed on a distribution line, different short - circuit current distribution characteristics, zero - sequence voltage characteristics, and low - voltage characteristics will appear when short - circuit or single - phase grounding faults occur at different positions. Based on the short - circuit current distribution characteristics, zero - sequence voltage characteristics, and low - voltage characteristics, the relay protection action logic and the setting values of each protection action for the loop closing device of the phase - shifting transformer are designed.

[0043] The following takes the cases of short - circuit and single - phase grounding faults occurring on the left - hand side line after loop closing and short - circuit and single - phase grounding faults occurring on the left - hand side line before loop closing as examples for separate explanations.

[0044] For example, when a short - circuit occurs on the left - hand side line after loop closing, generally, instantaneous over - current protection is configured on the outgoing circuit breakers of the distribution line. Since the line is loop - closed, short - circuit current is provided to the short - circuit point from both sides of the line at this time. Therefore, the current protection on both sides of the line will operate. The reasonable logic should be that the current protection on the left - hand side line operates, the current protection on the tie switch operates, and the current protection on the right - hand side line should not operate.

[0045] Therefore, when the short - circuit point is on the left - hand side line after loop closing, the short - circuit current distribution characteristics obtained in the loop - closed line are that the outgoing circuit breaker of the left - hand side line and the left - hand side breaker of the phase - shifting transformer in the loop closing device flow through the same relatively large short - circuit current. Due to the current - limiting effect of the phase - shifting transformer, the outgoing circuit breaker of the right - hand side line and the right - hand side breaker of the phase - shifting transformer in the loop closing device flow through the same relatively small short - circuit current. The instantaneous trip protection setting value of the right - hand side breaker of the phase - shifting transformer is less than the operating value of the instantaneous over - current protection of the outgoing circuit breaker of the right - hand side line. Therefore, the current protection on the left - hand side line and the current protection on the loop closing device operate. Under the action of the acceleration logic, the breaker in the loop closing device trips quickly, the fault is removed, and the loop closing device is blocked. Since the fault on the right - hand side line has been removed, the over - current protection returns without tripping.

[0046] Another example is that when a single - phase grounding fault occurs on the left - hand side line after loop closing, generally, when a single - phase grounding occurs in a 10 kV distribution line, the insulation monitoring device based on zero - sequence voltage monitoring on the bus will give an alarm but will not act on tripping. So at this time, the tie switch will not automatically open the loop. The reasonable logic should be to disconnect the loop closing device to avoid the spread of the fault.

[0047] Therefore, when a single - phase grounding fault occurs on the left - hand side line after loop closing, the zero - sequence voltage distribution characteristics in the loop - closed line are that zero - sequence voltage is detected on the left - hand side of the phase - shifting transformer. Because the phase - shifting transformer uses a Y / Z connection, there is no zero - sequence voltage on the right - hand side of the phase - shifting transformer. At this time, the single - phase grounding protection in the loop closing device operates and gives an alarm signal indicating a single - phase grounding fault on the left - hand side line.

[0048] For another example, a short circuit occurs in the left - hand line before closing the loop. Generally, since the tie switch is not closed, the over - current protection at the tie switch does not detect the short - circuit current and will not operate, and the tie switch will not be blocked. After closing, the over - current protection operates. The reasonable logic is that the loop - closing device should be blocked to avoid closing onto the equipment under the impact of short - circuit current and the expansion of the short - circuit fault range.

[0049] Therefore, when a short circuit occurs in the left - hand line before closing the loop, the low - voltage characteristic in the loop - closing line is that a low voltage is detected on the left side of the phase - shifting transformer. At this time, the low - voltage protection in the loop - closing device operates to block the closing device.

[0050] For another example, a single - phase grounding fault occurs in the left - hand line before closing the loop. Generally, the tie switch will not be blocked, and the closing operation can be carried out. After closing, since the tie switch has no single - phase grounding protection, it will neither adjust nor alarm. The reasonable logic is that the loop - closing device should be blocked to avoid closing onto the fault and causing potential safety hazards.

[0051] Therefore, when a single - phase grounding fault occurs in the left - hand line before closing the loop, the zero - sequence voltage distribution characteristic in the loop - closing line is that a zero - sequence voltage is detected on the left side of the phase - shifting transformer. At this time, the single - phase grounding protection based on the zero - sequence voltage start in the loop - closing device operates to block the closing device.

[0052] As Figure 3 shown, the present invention also provides a device for protecting loop - closing without power interruption in a distribution line. The device includes: an acquisition module, a setting module, and a protection module. The device will be described below.

[0053] The acquisition module is used to acquire the short - circuit current distribution characteristic and the zero - sequence voltage and low - voltage distribution characteristics in the loop - closing line;

[0054] The setting module is connected to the acquisition module and is used to configure the action logic and setting values of the overall protection scheme according to the acquired short - circuit current distribution characteristic and voltage characteristic;

[0055] The protection module is connected to the setting module and is used to protect the loop - closing line according to the protection logic and action values configured by the setting.

[0056] The acquisition module includes a current detection circuit, a low - voltage detection circuit, and a zero - sequence voltage detection circuit; the current detection circuit is used to detect the short - circuit current distribution in the loop - closing line; the low - voltage detection circuit is used to detect the low voltage when a short circuit occurs in the loop - closing line; the zero - sequence voltage detection circuit is used to detect the zero - sequence voltage that appears after a single - phase grounding fault occurs in the loop - closing line.

[0057] The protection module includes a protection action acceleration circuit, which is used to accelerate the tripping of both sides of the phase - shifting transformer in the loop - closing device when a short circuit occurs on either side of the loop - closing line.

[0058] The protection device further includes a loop closing device locking circuit, which is used to lock the loop closing device when a short circuit or single-phase grounding occurs on any side of the line before loop closing; after loop closing, when a short circuit or single-phase grounding occurs on any side of the line, after accelerating the tripping of the circuit breakers on both sides of the phase-shifting transformer in the loop closing device, the loop closing device is locked.

[0059] The present invention can solve the technical problems that the existing current protection for distribution lines cannot meet the requirements of protection selectivity and quick operation in the loop closing state and cannot accurately monitor and locate single-phase grounding faults.

Claims

1. A non-stop closing relay protection method for distribution lines, characterized in that: In the loop closing device, the circuit breakers on both sides of the phase-shifting transformer are configured with quick-break protection, overcurrent protection, single-phase grounding protection based on zero-sequence voltage startup, and low voltage protection, including the following steps: S1, obtaining the short-circuit current distribution characteristics and voltage characteristics of the closed-loop line; S2, designing the protection logic of the loop closing device for the phase-shifting transformer according to the acquired short-circuit current distribution characteristics and voltage characteristics; the loop closing device protection logic is as follows: Before the closing operation, the single-phase grounding protection action or low voltage protection action initiated by the zero-sequence voltage on either side of the circuit breaker on both sides should terminate the closing operation; When the line on the left side of the closing switch is short-circuited, the current protection of the left distribution line is activated, the current protection at the circuit breaker on the left side of the phase-shifting transformer is activated, the left distribution line is cut off, and the protection of the outgoing line switch of the right closing line does not operate; When the line on the right side of the closing switch is short-circuited, the current protection of the right distribution line is activated, the current protection at the circuit breaker on the right side of the phase-shifting transformer is activated, the right distribution line is cut off, and the protection of the outgoing line switch of the left closing line does not operate; When single-phase grounding occurs in the line on the left side of the closing switch, the zero-sequence voltage single-phase grounding protection on the left side of the phase-shifting transformer is activated, and a single-phase grounding fault alarm signal is sent on the left side, the circuit breaker on the left side of the phase-shifting transformer is tripped, and the outgoing line switch protection on the right side of the closing switch does not operate; When single-phase grounding occurs in the line on the right side of the closing switch, the zero-sequence voltage single-phase grounding protection on the right side of the phase-shifting transformer is activated, and a single-phase grounding fault alarm signal on the right side is sent, the circuit breaker on the right side of the phase-shifting transformer is tripped, and the protection of the outgoing switch of the closing line on the left side does not operate; S3, according to the configured closing device protection logic, short-circuit protection is performed on the distribution line during the closing operation.

2. The non-stop closing relay protection method for distribution lines according to claim 1 is characterized in that: By configuring current detection elements, zero-sequence voltage and low-voltage detection elements in the circuit breakers on both sides of the phase-shifting transformer in the closing device, the current characteristics, three-phase voltage and zero-sequence voltage characteristics of the closing lines on both sides are detected.

3. The non-stop closing relay protection method for distribution lines according to claim 1 is characterized in that: The current protection action value of the circuit breaker on the left side of the phase-shifting transformer is set according to the short-circuit current flowing through the circuit breaker on the left side when the line is closed; The current protection action value of the circuit breaker on the right side of the phase-shifting transformer in the closing device is set according to the short-circuit current flowing through the right circuit breaker at the left outlet of the phase-shifting transformer when the line is closed.

4. The non-stop closing relay protection method for distribution lines according to claim 1 is characterized in that: The circuit breakers on both sides of the phase-shifting transformer are configured with tripping acceleration logic. When a short circuit or single-phase grounding occurs on one side of the line, if the circuit breakers on both sides of the phase-shifting transformer are in the closed state, the circuit breaker adjustment acceleration circuit is connected and the circuit breaker is accelerated to trip.

5. The non-stop closing relay protection method for distribution lines according to claim 1 is characterized in that: When the distribution line is closed, the relay protection action logic and each protection action setting value of the closing device of the phase-shifting transformer are designed according to the short-circuit current distribution characteristics and zero-sequence voltage and low voltage characteristics: When a short circuit occurs in the left line after the loop is closed, the short-circuit current distribution characteristics in the closed line are that the left line outgoing circuit breaker and the left circuit breaker of the phase-shifting transformer of the closing device flow through the same large short-circuit current, and the right line outgoing circuit breaker and the right circuit breaker of the phase-shifting transformer of the closing device flow through the same small short-circuit current. The setting value of the quick-break protection of the right circuit breaker of the phase-shifting transformer is less than the quick-break protection action value of the right line outgoing circuit breaker. The current protection of the left line and the current protection on the closing device are activated. Under the action of the acceleration logic, the circuit breaker in the closing device is accelerated to trip, the fault is cut off and the closing device is locked. The right line has been cut off due to the fault, and the overcurrent protection returns without tripping. When a single-phase grounding fault occurs in the left line after the loop is closed, the zero-sequence voltage distribution characteristic in the closed line is that the zero-sequence voltage is detected on the left side of the phase-shifting transformer, and there is no zero-sequence voltage on the right side of the phase-shifting transformer. At this time, the single-phase grounding protection in the closing device is activated, and a single-phase grounding alarm signal occurs on the left line; When a short circuit occurs in the left line before closing the loop, the low voltage feature in the closing line is that a low voltage is detected on the left side of the phase-shifting transformer. At this time, the low voltage protection in the closing device is activated and the closing device is locked; When a single-phase grounding fault occurs in the left line before closing the loop, the zero-sequence voltage distribution characteristic in the closing line is that the zero-sequence voltage is detected on the left side of the phase-shifting transformer. At this time, the single-phase grounding protection in the closing device based on the zero-sequence voltage is activated and the closing device is locked.

6. A non-stop closing relay protection device for distribution lines, characterized in that: Used to execute the non-stop closing relay protection method for distribution lines as claimed in any one of claims 1 to 5, comprising: An acquisition module is used to acquire the short-circuit current distribution characteristics and voltage characteristics of the closed-loop line before and after the closed-loop; A setting module, connected to the acquisition module, for configuring the current protection, single-phase grounding protection and low voltage protection action logic on the circuit breakers on both sides of the loop closing device; A protection module, connected to the setting module, for protecting the closed-loop line according to the configured protection logic; The closing lockout circuit is used to lock the closing device if a short circuit or single-phase grounding is detected on either side of the line before and after the closing operation; after closing, if a short circuit or single-phase grounding occurs on either side of the line, the circuit breakers on both sides of the phase-shifting transformer in the closing device are accelerated to open and close, and then the closing device is locked.

Images