CN213027446U - Switching device for controllable lightning arrester - Google Patents
Switching device for controllable lightning arrester Download PDFInfo
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- CN213027446U CN213027446U CN202021352687.2U CN202021352687U CN213027446U CN 213027446 U CN213027446 U CN 213027446U CN 202021352687 U CN202021352687 U CN 202021352687U CN 213027446 U CN213027446 U CN 213027446U
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- thyristor
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- thyristor valve
- mechanical switch
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Abstract
The utility model relates to a switching device for a controllable lightning arrester, which adopts a circuit structure that a thyristor valve and a mechanical switch are connected in parallel, wherein, the thyristor valve has fast conduction time and high controllability; the mechanical switch is used for transferring over-current in the thyristor valve so as to ensure that the thyristor valve is free from large-current stress; on the other hand, stray inductance of the thyristor valve and a mechanical switch loop is small, so that the current conversion speed of the thyristor valve and the mechanical switch is greatly improved, and the current of a thyristor branch circuit is ensured to enter a blocking state as early as possible.
Description
Technical Field
The utility model relates to an electric power system electrical equipment field, concretely relates to a switching device for controllable arrester.
Background
The hybrid cascade extra-high voltage direct current transmission receiving end converter station adopts a high-end LCC (line Committed converter) series low-end VSC (Voltage Source converter). When a receiving end alternating current power grid fails, on one hand, the receiving end LCC fails to convert phase and is put into bypass to cause a direct current bus to charge a low-end VSC converter valve; on the other hand, the receiving-end alternating current power grid no longer receives active power, resulting in surplus direct current line power. The overvoltage working condition of the VSC converter can be caused by the two reasons. A controllable lightning arrester can be used to solve the above problems. When the system works normally, the controllable lightning arresters are all connected to the direct-current bus; when the problems occur, the controllable part of the controllable lightning arrester is bypassed by the switch, so that the direct current voltage is limited, and surplus power is discharged.
The electronic switching scheme adopting the thyristor valve has the advantages of stable triggering and high conducting speed. The traditional thyristor valve adopts a distributed saturable reactor in series connection to inhibit the voltage and the current with high change rate, but the topology can cause the problem that the current follow current time of the saturable reactor is too long when the thyristor valve and a mechanical switch are in current conversion; because the thyristor has no self-turn-off capability, the thyristor cannot be turned off within a specified time due to the overlong follow current time, and the performance of the controllable lightning arrester is influenced.
SUMMERY OF THE UTILITY MODEL
Based on the above-mentioned defect of prior art, the to-be-solved technical problem of the utility model is that, overcome the defect of current afterflow time overlength of current thyristor switching device, provide a take centralized saturable reactor's novel switching device.
To achieve the above object, the present invention provides a switching device for a controllable arrester, the switching device comprising a thyristor valve, a mechanical switch, and a saturable reactor; the positive pole of the mechanical switch is connected with the anode of the thyristor valve, and the negative pole of the mechanical switch is connected with the cathode of the thyristor valve, so that a parallel loop is formed; the anode side of the thyristor valve is the high-voltage end of the parallel circuit, and the cathode side of the thyristor valve is the low-voltage end of the parallel circuit; the low-voltage end of the saturable reactor is connected with the high-voltage end of the parallel loop, and the high-voltage end of the saturable reactor is connected with the direct-current bus; and the low-voltage end of the parallel loop is grounded.
Further, the low-voltage end of the saturable reactor is simultaneously connected with the positive electrode of the mechanical switch and the anode of the thyristor valve.
Further, the thyristor valve comprises: the thyristor control system comprises a plurality of thyristor devices connected in series and unit control modules corresponding to the thyristor devices, wherein each unit control module is connected in parallel with a cathode and a gate of each thyristor device, the unit control modules are used for detecting voltages at two ends of the thyristor devices connected in parallel with the unit control modules, comparing the voltages at the two ends of the thyristor devices with a preset threshold value, and triggering the thyristor devices connected in parallel with the unit control modules to be conducted when the voltages at the two ends of the thyristor devices are greater than the preset threshold value.
Further, the switching device is connected in parallel with the controllable part of the controllable lightning arrester when used for the controllable lightning arrester.
Further, when the voltage of the direct current bus rises, the switching device acts to bypass the controllable part of the controllable lightning arrester, and the controllable lightning arrester fixing part and the switching device form a series branch circuit to limit direct current overvoltage and provide an energy leakage loop.
Further, the mechanical switch is a multi-break vacuum switch.
Further, the control signals of the thyristor valve and the mechanical switch are optical signals transmitted through optical fibers.
In summary, the utility model provides a switching device for a controllable lightning arrester, which adopts a circuit structure that a thyristor valve and a mechanical switch are connected in parallel, wherein the thyristor valve has fast conduction time and high controllability; the mechanical switch is used for transferring over-current in the thyristor valve so as to ensure that the thyristor valve is free from large-current stress; on the other hand, stray inductance of the thyristor valve and a mechanical switch loop is small, so that the current conversion speed of the thyristor valve and the mechanical switch is greatly improved, and the current of a thyristor branch circuit is ensured to enter a blocking state as early as possible.
Drawings
Fig. 1 is a switching device topology for a controllable arrester of the present invention;
FIG. 2 is a schematic structural view of a thyristor valve in the switching device of the present invention
Fig. 3 is a circuit topology of the switching device of fig. 1 for a controllable arrester;
FIG. 4 is a prior art thyristor switching device circuit topology;
FIG. 5 is a current waveform diagram of a prior art thyristor switched device commutation process;
fig. 6 is a current waveform diagram of a switching device commutation process according to the present invention;
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the description is intended to be illustrative only and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
The utility model provides a switching device for controllable arrester, the principle topological diagram of the switching device is shown in figure 1, the switching device comprises a thyristor valve 1, a mechanical switch 2 and a saturable reactor 3; the positive pole of the mechanical switch 2 is connected with the anode of the thyristor valve 1, and the negative pole of the mechanical switch 2 is connected with the cathode of the thyristor valve 1, so that a parallel loop is formed; the anode side of the thyristor valve 1 is the high-voltage end of the parallel circuit, and the cathode side of the thyristor valve 1 is the low-voltage end of the parallel circuit; the low-voltage end of the saturable reactor 3 is connected with the high-voltage end of the parallel loop, and the high-voltage end of the saturable reactor 3 is connected with a direct-current bus; and the low-voltage end of the parallel loop is grounded. The low-voltage end of the saturable reactor 3 is connected with the positive electrode of the mechanical switch 2 and the anode of the thyristor valve 1 at the same time, namely, is connected with a parallel circuit formed by the thyristor valve 1 and the mechanical switch 2. The mechanical switch 2 is a multi-break vacuum switch, and the control signals of the thyristor valve 1 and the mechanical switch 2 are optical signals transmitted through optical fibers.
According to some embodiments, the circuit structure of the thyristor valve 1 in the switching apparatus is as shown in fig. 2, and the switching apparatus includes a plurality of thyristor devices connected in series, and a unit control module corresponding to each thyristor device, where each unit control module is connected in parallel to a cathode and a gate of each thyristor device, and the unit control module is configured to detect a voltage across each thyristor device connected in parallel to the unit control module, compare the voltage across each thyristor device with a preset threshold, and trigger the thyristor device connected in parallel to the unit control module to turn on when the voltage across each thyristor device is greater than the preset threshold.
Fig. 3 shows a circuit topology when the switching device provided by the present invention is used in a controllable lightning arrester. As shown in fig. 3, the switching device a, when used in a controllable arrester, is connected in parallel with the controllable part 5 of the controllable arrester, which controllable part 5 is connected in series with the fixed part 4. When the voltage of the direct current bus rises, the switching device A acts to bypass the controllable part 5 of the controllable lightning arrester, and at the moment, the fixed part 4 of the controllable lightning arrester and the switching device A form a series branch circuit to limit direct current overvoltage and provide an energy release loop. Firstly, a thyristor valve 1 is conducted, and a bleeder current flows through a saturable reactor 3 and the thyristor valve 1; meanwhile, the mechanical switch 2 is switched on, because the speed of the mechanical switch 2 is slower than that of the thyristor valve 1, the mechanical switch 2 is switched on in place after a certain time delta t, and the mechanical switch 2 and the thyristor valve 1 start to convert current; the branch current of the thyristor valve 1 enters a blocking state after zero crossing, and when the system fault is finished, the bleeder current crosses zero, and the mechanical switch 2 is switched off.
Will the utility model provides a switching device contrasts with traditional thyristor switching device among the prior art. As shown in fig. 4, in the conventional thyristor valve switching device, a thyristor valve 11 and a saturable reactor 13 are connected in series and then connected in parallel with a mechanical switch 12. When the thyristor valve 11 branch and the mechanical switch 12 branch are commutated, because the current of the saturable reactor 13 cannot be suddenly changed, the commutation speed is slow and the commutation time is long. The commutation time depends on a time constant L/R of the commutation circuit, wherein L is the total inductance of the commutation loop, and R is the total resistance of the commutation loop. When the switching device provided by the utility model carries out current conversion, firstly, the thyristor valve 1 is conducted, and the bleeder current flows through the saturable reactor 3 and the thyristor valve 1; meanwhile, the mechanical switch 2 is switched on, because the speed of the mechanical switch 2 is slower than that of the thyristor valve 1, the mechanical switch 2 is switched on in place after a certain time delta t, and the mechanical switch 2 and the thyristor valve 1 start to convert current; the current of the branch of the thyristor valve 1 enters a blocking state after passing through zero, the leakage current passes through zero after the system fault is finished, and the mechanical switch 2 is switched off. From the above, the commutation time of the switch device depends on the time constant L/R of the commutation circuit, according to the utility model provides a switch device, the total inductance L of commutation loop is only the stray inductance of return circuit, and time constant L/R is very little compared in traditional thyristor valve switch device to commutation speed has been improved. The current waveform of the commutation process between the thyristor valve and the mechanical switch in the conventional thyristor valve switch device is shown in fig. 5, and the current waveform of the commutation process of the switch device of the present invention is shown in fig. 6. As can be seen from fig. 5 and 6, compared with the conventional thyristor valve switch device in the prior art, the switch device of the present invention greatly increases the commutation speed and shortens the time required for commutation.
In summary, the utility model provides a switching device for a controllable lightning arrester, which adopts a circuit structure that a thyristor valve and a mechanical switch are connected in parallel, wherein the thyristor valve has fast conduction time and high controllability; the mechanical switch is used for transferring over-current in the thyristor valve so as to ensure that the thyristor valve is free from large-current stress; on the other hand, stray inductance of the thyristor valve and a mechanical switch loop is small, so that the current conversion speed of the thyristor valve and the mechanical switch is greatly improved, and the current of a thyristor branch circuit is ensured to enter a blocking state as early as possible. Compared with the traditional thyristor valve switching device in the prior art, the current conversion speed is greatly improved, and the time required by current conversion is shortened.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.
Claims (6)
1. A switching device for a controllable arrester, characterized in that the switching device comprises a thyristor valve, a mechanical switch, and a saturable reactor;
the positive pole of the mechanical switch is connected with the anode of the thyristor valve, and the negative pole of the mechanical switch is connected with the cathode of the thyristor valve, so that a parallel loop is formed;
the anode side of the thyristor valve is the high-voltage end of the parallel circuit, and the cathode side of the thyristor valve is the low-voltage end of the parallel circuit; the thyristor valve comprises a plurality of thyristor devices connected in series and unit control modules corresponding to the thyristor devices, each unit control module is connected in parallel with a cathode and a gate of each thyristor device, the unit control modules are used for detecting voltages at two ends of the thyristor devices connected in parallel with the unit control modules, comparing the voltages at the two ends of the thyristor devices with a preset threshold value, and triggering the thyristor devices connected in parallel with the unit control modules to be conducted when the voltages at the two ends of the thyristor devices are greater than the preset threshold value;
the low-voltage end of the saturable reactor is connected with the high-voltage end of the parallel loop, and the high-voltage end of the saturable reactor is connected with the direct-current bus;
and the low-voltage end of the parallel loop is grounded.
2. The switching device according to claim 1, wherein the low voltage terminal of the saturable reactor simultaneously connects the positive electrode of the mechanical switch and the anode of the thyristor valve.
3. A switching device according to claim 1, characterized in that the switching device, when used in a controllable lightning conductor, is connected in parallel with the controllable part of the controllable lightning conductor.
4. A switching device according to claim 3, characterized in that the switching device is arranged to act to bypass the controllable part of the controllable arrester when the dc bus voltage rises, the controllable arrester part forming a series branch with the switching device to limit dc overvoltages and to provide a power dump loop.
5. The switching device according to claim 1, wherein the mechanical switch is a multi-break vacuum switch.
6. The switching device according to claim 1, wherein the control signals of the thyristor valve and the mechanical switch are optical signals transmitted through optical fibers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021352687.2U CN213027446U (en) | 2020-07-10 | 2020-07-10 | Switching device for controllable lightning arrester |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021352687.2U CN213027446U (en) | 2020-07-10 | 2020-07-10 | Switching device for controllable lightning arrester |
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| Publication Number | Publication Date |
|---|---|
| CN213027446U true CN213027446U (en) | 2021-04-20 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202021352687.2U Active CN213027446U (en) | 2020-07-10 | 2020-07-10 | Switching device for controllable lightning arrester |
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| CN (1) | CN213027446U (en) |
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- 2020-07-10 CN CN202021352687.2U patent/CN213027446U/en active Active
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