A single-phase grounding arc suppression method for flexible distribution network

Abstract

A flexible distribution network single-phase grounding arc suppression device and arc suppression method, relating to a grid grounding arc suppression technology, is intended to address the problem of poor arc suppression sensitivity of existing parallel resistance arc suppression coils. In the present invention, when the compensation system is operating normally, the first arc suppression coil L1 is put into operation, the first thyristor VT1 and the second thyristor VT2 are both in a fully conductive state, the second arc suppression coil L2 is in a short-circuit state, and the compensation system is in a semi-compensated state; when a single-phase fault occurs on the distribution network bus, the gates of the first thyristor VT1 and the second thyristor VT2 are adjusted so that the first arc suppression coil L1 and the second arc suppression coil L2 are put into operation in series, and the compensation system enters a fully compensated state; and the semi-compensated state and the fully compensated state are switched in real time according to the detection results of the control module. The beneficial effect is that the arc suppression sensitivity is high.

Description

Technical Field

[0001] The invention relates to a power grid grounding arc suppression technology. Background Art

[0002] At present, most of my country's distribution networks use ungrounded or arc suppression coil grounding methods to eliminate arcs. The inductive current flowing through the arc suppression coil compensates for the single-phase grounding fault and generates capacitive current. The capacitive current rapidly reduces the residual current to achieve rapid arc extinguishing. With the continuous expansion of the scale of distribution network cable lines, the existing arc suppression coil compensation method cannot meet the requirements of rapid arc extinguishing, and the parallel resistance arc suppression coil has come into being. The parallel resistance arc suppression coil uses switch switching to achieve real-time adjustment of the arc suppression coil, and can only be roughly adjusted. That is, the parallel resistance arc suppression coil has poor arc extinguishing sensitivity. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem of poor arc extinguishing sensitivity of existing parallel resistance arc extinguishing coils, and propose a single-phase grounding arc extinguishing method for a flexible distribution network.

[0004] A flexible distribution network single-phase grounding arc suppression device according to the present invention includes a control module and a compensation system;

[0005] The control module is used to detect whether a single-phase fault occurs in the busbar of the distribution network, and to generate a control signal when a single-phase fault occurs in the busbar of the distribution network;

[0006] The compensation system includes a first arc suppression coil L1, a second arc suppression coil L2, a first thyristor VT1 and a second thyristor VT2;

[0007] One end of the first arc suppression coil L1 is connected to the neutral point of the distribution network grounding line, and the other end of the first arc suppression coil L1 is connected to one end of the second arc suppression coil L2, the cathode of the first thyristor VT1 and the anode of the second thyristor VT2;

[0008] The other end of the second arc suppression coil L2 is connected to the anode of the first thyristor VT1 and the cathode of the second thyristor VT2, and is grounded;

[0009] The gate of the first thyristor VT1 and the gate of the second thyristor VT2 receive the control signal simultaneously.

[0010] Furthermore, the first thyristor VT1 and the second thyristor VT2 are both gate-turn-off thyristors.

[0011] Furthermore, the impedance value of the second arc suppression coil L2 is 10% to 20% times the impedance value of the first arc suppression coil L1.

[0012] A single-phase grounding arc extinguishing method for a flexible distribution network is implemented based on a single-phase grounding arc extinguishing device for a flexible distribution network;

[0013] The arc extinguishing method comprises the following steps:

[0014] Step 1: Initially, the compensation system is in a semi-compensation state, and the control module is used to collect the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state in real time;

[0015] Step 2: Calculate the zero-sequence current information of the distribution network in the semi-compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state acquired in step 1;

[0016] Step 3: Compare the zero-sequence current information of the distribution network in the semi-compensated state calculated in step 2 with the zero-sequence current information threshold value preset in the control module to determine whether the calculated zero-sequence current information of the distribution network in the semi-compensated state is the same as the zero-sequence current information threshold value preset in the control module. If they are not the same, execute step 4; otherwise, execute step 9;

[0017] Step 4: Determine the specific location where the single-phase fault occurs on the distribution network busbar;

[0018] Step 5: The control module generates a control signal and sends it to the compensation system located at the specific location of the single-phase fault on the distribution network bus determined in step 4, and the compensation system is in a full compensation state;

[0019] Step 6: The control module collects the zero-sequence voltage of the distribution network bus at each moment when the compensation system is in a fully compensated state;

[0020] Step 7: Calculate the zero-sequence current information of the distribution network in the full compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the full compensation state acquired in step 6;

[0021] Step 8: Compare the zero-sequence current information of the distribution network under the full compensation state calculated in step 7 with the zero-sequence current information threshold preset in the control module to determine whether the calculated zero-sequence current information of the distribution network under the full compensation state is the same as the zero-sequence current information threshold preset in the control module. If they are not the same, return to step 5; otherwise, execute step 9.

[0022] Step 9: The compensation system of the distribution network operates in a semi-compensation state.

[0023] Furthermore, the specific method for calculating the zero-sequence current information of the distribution network in the semi-compensated state in step 2 is: in the semi-compensated state, the current measurement value at one moment after the fault is subtracted from the current measurement value at one moment before the fault to obtain the current difference, and the current difference is the zero-sequence current information of the distribution network in the semi-compensated state.

[0024] Furthermore, the specific method for calculating the zero-sequence current information of the distribution network under the full compensation state in step seven is: in the full compensation state, the current measurement value at the moment after the fault is subtracted from the current measurement value at the moment before the fault to obtain the current difference, and the current difference is the zero-sequence current information of the distribution network under the full compensation state.

[0025] The beneficial effects of the present invention are as follows: based on the control of the first thyristor VT1 and the second thyristor VT2, the switching of the connection and connection of the second arc suppression coil L2 is realized, and at the same time, the first arc suppression coil L1 and the second arc suppression coil L2 constitute a control strategy of the master-slave arc suppression coil, which is the key to the compensation system. The triggering conduction angle of the first thyristor VT1 and the second thyristor VT2 directly determines the compensation effect of the system; when the compensation system is operating normally, the first arc suppression coil L1 is put into operation, the first thyristor VT1 and the second thyristor VT2 are both in a fully conductive state, the second arc suppression coil L2 is in a short-circuit state, and the compensation system is in a semi-compensated state; when a single-phase fault occurs on the distribution network bus, Adjust the gates of the first thyristor VT1 and the second thyristor VT2 so that the first arc suppression coil L1 and the second arc suppression coil L2 are put into operation in series, and the compensation system enters the full compensation state; according to the measured zero-sequence current information value, adjust the second arc suppression coil L2 to quickly reach the full compensation point to complete the fault arc suppression; after the fault is eliminated, the first thyristor VT1 and the second thyristor VT2 continue to operate in full conduction, and the second arc suppression coil L2 returns to the short-circuit state, so that the compensation system is in a semi-compensation state, avoiding overvoltage when running in the full compensation state after arc suppression; the compensation system switches between the semi-compensation state and the full compensation state in real time according to the detection results of the control module. Therefore, the arc suppression device has a high sensitivity to arc suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a circuit diagram of the compensation system in the first embodiment;

[0027] Figure 2 This is a flow chart of a single-phase grounding arc extinguishing method for a flexible distribution network as described in the fourth specific implementation method. DETAILED DESCRIPTION

[0028] Specific implementation method 1: Combination Figure 1 This embodiment describes a single-phase grounding arc suppression device for a flexible distribution network, which includes a control module and a compensation system.

[0029] The control module is used to detect whether a single-phase fault occurs in the busbar of the distribution network, and to generate a control signal when a single-phase fault occurs in the busbar of the distribution network;

[0030] The compensation system includes a first arc suppression coil L1, a second arc suppression coil L2, a first thyristor VT1 and a second thyristor VT2;

[0031] One end of the first arc suppression coil L1 is connected to the neutral point of the distribution network grounding line, and the other end of the first arc suppression coil L1 is connected to one end of the second arc suppression coil L2, the cathode of the first thyristor VT1 and the anode of the second thyristor VT2;

[0032] The other end of the second arc suppression coil L2 is connected to the anode of the first thyristor VT1 and the cathode of the second thyristor VT2, and is grounded;

[0033] The gate of the first thyristor VT1 and the gate of the second thyristor VT2 receive the control signal simultaneously.

[0034] In this embodiment, based on the control of the first thyristor VT1 and the second thyristor VT2, the switching of the connection and connection of the second arc suppression coil L2 is realized. At the same time, the first arc suppression coil L1 and the second arc suppression coil L2 constitute a control strategy of the master-slave arc suppression coil (wherein the first arc suppression coil L1 is the main arc suppression coil; the second arc suppression coil L2 is the auxiliary arc suppression coil). This control strategy is the key to the compensation system. The triggering conduction angle of the first thyristor VT1 and the second thyristor VT2 directly determines the compensation effect of the system; when the compensation system is operating normally, the first arc suppression coil L1 is put into operation, the first thyristor VT1 and the second thyristor VT2 are both in the fully conductive state, the second arc suppression coil L2 is in the short-circuit state, and the compensation system is in a semi-compensated state. state; when a single-phase fault occurs on the distribution network bus, the gates of the first thyristor VT1 and the second thyristor VT2 are adjusted so that the first arc suppression coil L1 and the second arc suppression coil L2 are put into operation in series, and the compensation system enters the full compensation state; according to the measured zero-sequence current information value, the second arc suppression coil L2 is adjusted to quickly reach the full compensation point to complete the fault arc extinguishing; after the fault is eliminated, the first thyristor VT1 and the second thyristor VT2 continue to operate in full conduction, and the second arc suppression coil L2 is restored to the short-circuit state, so that the compensation system is in a semi-compensation state, avoiding overvoltage when running in the full compensation state after arc extinguishing; the compensation system switches between the semi-compensation state and the full compensation state in real time according to the detection result of the control module, so the arc extinguishing sensitivity of the arc suppression device is relatively high.

[0035] Specific embodiment 2: This embodiment further limits the single-phase grounding arc suppression device for a flexible power distribution network described in specific embodiment 1. In this embodiment, both the first thyristor VT1 and the second thyristor VT2 are gate-off thyristors.

[0036] Specific embodiment three: This embodiment further limits the single-phase grounding arc suppression device for a flexible distribution network described in specific embodiment one. In this embodiment, the impedance value of the second arc suppression coil L2 is 10% to 20% times the impedance value of the first arc suppression coil L1.

[0037] Specific implementation method four: Combination Figure 2 This embodiment describes a method for single-phase grounding arc suppression in a flexible distribution network. This arc suppression method is implemented based on a single-phase grounding arc suppression device in a flexible distribution network described in the first embodiment.

[0038] The arc extinguishing method comprises the following steps:

[0039] Step 1: Initially, the compensation system is in a semi-compensation state, and the control module is used to collect the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state in real time;

[0040] Step 2: Calculate the zero-sequence current information of the distribution network in the semi-compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state acquired in step 1;

[0041] Step 3: Compare the zero-sequence current information of the distribution network in the semi-compensated state calculated in step 2 with the zero-sequence current information threshold value preset in the control module to determine whether the calculated zero-sequence current information of the distribution network in the semi-compensated state is the same as the zero-sequence current information threshold value preset in the control module. If they are not the same, execute step 4; otherwise, execute step 9;

[0042] Step 4: Determine the specific location where the single-phase fault occurs on the distribution network busbar;

[0043] Step 5: The control module generates a control signal and sends it to the compensation system located at the specific location of the single-phase fault on the distribution network bus determined in step 4, and the compensation system is in a full compensation state;

[0044] Step 6: The control module measures and collects the zero-sequence voltage of the distribution network busbar at every moment when the compensation system is in a fully compensated state in real time;

[0045] Step 7: Calculate the zero-sequence current information of the distribution network in the full compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the full compensation state acquired in step 6;

[0046] Step 8: Compare the zero-sequence current information of the distribution network under the full compensation state calculated in step 7 with the zero-sequence current information threshold preset in the control module to determine whether the calculated zero-sequence current information of the distribution network under the full compensation state is the same as the zero-sequence current information threshold preset in the control module. If they are not the same, return to step 5; otherwise, execute step 9.

[0047] Step 9: The compensation system of the distribution network operates in a semi-compensation state.

[0048] In this embodiment, in step three, if the calculated zero-sequence current information of the distribution network in the semi-compensated state is different from the zero-sequence current information threshold preset in the control module, it is determined that a single-phase fault has occurred in the distribution network bus; the zero-sequence impedance amplitude of the distribution network is much larger than the transition resistance value, then the zero-sequence current information of the faulty line is much larger than the zero-sequence current information of the normal line, and accordingly, by comparing the zero-sequence current information of each line, the line with the largest amplitude is the faulty line; at the same time, in step eight, if the calculated zero-sequence current information of the distribution network in the fully compensated state is different from the zero-sequence current information threshold preset in the control module, then the second arc suppression coil L2 is in a state of being connected in series with the first arc suppression coil L1, then the compensation system is in a fully compensated state; if only the first arc suppression coil L1 is in a connected state, and the second arc suppression coil L2 is in a short-circuit state, then the compensation system is in a semi-compensated state.

[0049] In this embodiment, the zero-sequence current information threshold preset in the control module is the zero-sequence current information of the non-fault line; the zero-sequence current information of the non-fault line is determined by the following formula:

[0050]

[0051] Among them, ΔI 0m It is the zero-sequence current information threshold preset in the control module; Z 0m is the zero-sequence impedance of the fault line to ground; ΔU0 is the change in zero-sequence voltage caused by compensation by the first arc suppression coil L1 after the fault.

[0052] Specific embodiment five: This embodiment further limits the single-phase grounding arc extinguishing method of a flexible distribution network described in specific embodiment four. In this embodiment, the specific method for calculating the zero-sequence current information of the distribution network in the semi-compensated state in step two is: in the semi-compensated state, the current measurement value at one moment after the fault is subtracted from the current measurement value at one moment before the fault to obtain the current difference. The current difference is the zero-sequence current information of the distribution network in the semi-compensated state.

[0053] Specific embodiment six: This embodiment further limits the single-phase grounding arc extinguishing method of a flexible distribution network described in specific embodiment four. In this embodiment, the specific method for calculating the zero-sequence current information of the distribution network under the full compensation state in step seven is: under the full compensation state, the current measurement value at one moment after the fault is subtracted from the current measurement value at one moment before the fault to obtain the current difference. The current difference is the zero-sequence current information of the distribution network under the full compensation state.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for arc extinguishing in a single-phase grounding condition in a flexible distribution network, the method being implemented based on a single-phase grounding arc extinguishing device for a flexible distribution network; the arc extinguishing device comprising a control module and a compensation system; The control module is used to detect whether a single-phase fault occurs in the busbar of the distribution network, and to generate a control signal when a single-phase fault occurs in the busbar of the distribution network; The compensation system includes a first arc suppression coil L1, a second arc suppression coil L2, a first thyristor VT1 and a second thyristor VT2; One end of the first arc suppression coil L1 is connected to the neutral point of the distribution network grounding line, and the other end of the first arc suppression coil L1 is connected to one end of the second arc suppression coil L2, the cathode of the first thyristor VT1 and the anode of the second thyristor VT2; The other end of the second arc suppression coil L2 is connected to the anode of the first thyristor VT1 and the cathode of the second thyristor VT2, and is grounded; The gate of the first thyristor VT1 and the gate of the second thyristor VT2 receive the control signal simultaneously; It is characterized in that the arc extinguishing method comprises the following steps: Step 1: Initially, the compensation system is in a semi-compensation state, and the control module is used to collect the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state in real time; Step 2: Calculate the zero-sequence current information of the distribution network in the semi-compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the semi-compensation state acquired in step 1; Step 3: Compare the zero-sequence current information of the distribution network in the semi-compensated state calculated in step 2 with the zero-sequence current information threshold value preset in the control module to determine whether the calculated zero-sequence current information of the distribution network in the semi-compensated state is the same as the zero-sequence current information threshold value preset in the control module. If they are not the same, execute step 4; otherwise, execute step 9; Step 4: Determine the specific location where the single-phase fault occurs on the distribution network busbar; Step 5: The control module generates a control signal and sends it to the compensation system located at the specific location of the single-phase fault on the distribution network bus determined in step 4, and the compensation system is in a full compensation state; Step 6: The control module collects the zero-sequence voltage of the distribution network busbar at every moment when the compensation system is in a fully compensated state in real time; Step 7: Calculate the zero-sequence current information of the distribution network in the full compensation state based on the zero-sequence voltage of the distribution network busbar at each moment when the compensation system is in the full compensation state acquired in step 6; Step 8: Compare the zero-sequence current information of the distribution network under the full compensation state calculated in step 7 with the zero-sequence current information threshold preset in the control module to determine whether the calculated zero-sequence current information of the distribution network under the full compensation state is the same as the zero-sequence current information threshold preset in the control module. If they are not the same, return to step 5; otherwise, execute step 9. Step 9: The compensation system of the distribution network operates in a semi-compensation state; The semi-compensation state means that when the compensation system is operating normally, the first arc suppression coil L1 is put into operation, the first thyristor VT1 and the second thyristor VT2 are both in the fully conductive state, the second arc suppression coil L2 is in the short-circuit state, and the compensation system is in the semi-compensation state.

2. A method for single-phase grounding arc suppression in a flexible distribution network according to claim 1, characterized in that: The first thyristor VT1 and the second thyristor VT2 are both gate-turn-off thyristors.

3. A method for single-phase grounding arc suppression in a flexible distribution network according to claim 1, characterized in that: The impedance value of the second arc-extinguishing coil L2 is 10% to 20% times the impedance value of the first arc-extinguishing coil L1.

4. A method for single-phase grounding arc suppression in a flexible distribution network according to claim 1, characterized in that: The specific method for calculating the zero-sequence current information of the distribution network in the semi-compensated state in step 2 is: in the semi-compensated state, the current measurement value at the moment after the fault is subtracted from the current measurement value at the moment before the fault to obtain the current difference. The current difference is the zero-sequence current information of the distribution network in the semi-compensated state.

5. A method for single-phase grounding arc suppression in a flexible distribution network according to claim 1, characterized in that: The specific method for calculating the zero-sequence current information of the distribution network under the full compensation state in step seven is: under the full compensation state, the current measurement value at the moment after the fault is subtracted from the current measurement value at the moment before the fault to obtain the current difference. The current difference is the zero-sequence current information of the distribution network under the full compensation state.

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