CN219122332U - Power distribution network ground protection control device based on conduction angle is controllable - Google Patents
Power distribution network ground protection control device based on conduction angle is controllable Download PDFInfo
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- CN219122332U CN219122332U CN202222562893.1U CN202222562893U CN219122332U CN 219122332 U CN219122332 U CN 219122332U CN 202222562893 U CN202222562893 U CN 202222562893U CN 219122332 U CN219122332 U CN 219122332U
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Abstract
The utility model provides a power distribution network grounding protection control device based on controllable conduction angle, which comprises: arc suppression coil, one end of which is grounded; the system neutral point is connected with the other end of the arc suppression coil; the small resistor is connected with the arc suppression coil in parallel; the power device IGBT is connected in series with a parallel circuit of the small resistor and the arc suppression coil; the signal acquisition unit acquires parameter signals of the arc suppression coil, a system neutral point and a small resistor; the control unit is grounded at one end and is connected to a system neutral point at the other end; the power device IGBT is received and controlled to be triggered or cut off according to the parameter signals of the signal acquisition unit. The method changes the on state of the IGBT by controlling the trigger signal of the IGBT, thereby changing the current of a small resistance loop, detecting the gradient change condition of the zero sequence current of all lines by the gradient change of the current, judging the position of a fault loop and avoiding false actions.
Description
Technical Field
The utility model relates to the technical field of power supply and distribution network automation, in particular to a power distribution network grounding protection control device based on controllable conduction angle.
Background
At present, there are two grounding modes in most domestic distribution network systems: an arc suppression coil grounding mode and a small-resistance grounding mode. Both grounding modes have the application range and advantages and disadvantages.
The arc suppression coil grounding mode is mostly used for the power distribution network, eliminates arc grounding of the system, prevents non-fault phase overvoltage, can automatically eliminate transient faults, and can be electrified for 2 hours to improve the running stability of the power distribution network. But this grounding approach has problems: when the system has a grounding fault, the fault current is smaller, and the fault line is not easy to find, especially the high-resistance grounding fault.
For a neutral point through small resistance grounding system, when a single-phase grounding fault occurs, the zero sequence current of a fault line is rapidly increased due to the existence of the small resistance of the neutral point, and the magnitude of the zero sequence current is related to the capacitance current of the system, the small resistance of the neutral point and the magnitude of the grounding resistance. If the setting value of the protection is exceeded, the faulty line is cut off by the protection device. However, when the system has a single-phase permanent grounding fault, the fault current of the fault point is large, and if protection in the system is refused, the fault can be expanded. And once a single-phase permanent fault occurs, the line with the ground fault can trip immediately, and the power supply reliability is not high.
Disclosure of Invention
Aiming at the defects in the prior art, the utility model aims to provide a power distribution network grounding protection control device based on controllable conduction angle.
According to one aspect of the present utility model, there is provided a power distribution network ground protection control device based on conduction angle controllability, including:
the arc suppression coil is grounded at one end;
the system neutral point is connected with the other end of the arc suppression coil;
the small resistor is connected with the arc suppression coil in parallel;
the power device is connected in series with a parallel circuit of the small resistor and the arc suppression coil;
the signal acquisition unit acquires parameter signals of the arc suppression coil, a system neutral point and a small resistor;
the control unit is connected with the signal acquisition unit and the power device, and is used for receiving and controlling the triggering or cut-off of the power device according to the parameter signals of the signal acquisition unit.
Preferably, the power device is an insulated gate bipolar transistor, i.e. Insulated Gate Bipolar Transistor, abbreviated IGBT.
Preferably, the signal acquisition unit includes:
a voltage transformer, namely Potential Transformer, abbreviated as PT, wherein the voltage transformer PT is connected with the neutral point of the system and samples a voltage signal of the voltage transformer PT to be input into the control unit;
a current transformer, namely Current Transformer, abbreviated as CT, which is arranged on a series circuit of the neutral point of the system and the arc suppression coil, samples a current signal of the neutral point of the system and inputs the current signal to the control unit;
the infrared temperature measuring unit is connected with the small resistor and samples the small resistor to send a temperature signal to the control unit.
Preferably, the power device IGBT is located at the front end of the small resistor, and the current flowing through the small resistor loop is changed in real time by adjusting the trigger angle of the power device IGBT.
Preferably, the control unit adopts a variable square wave to control the power device IGBT in real time.
Preferably, the real-time control includes:
in one time period, the control is performed at 100% duty ratio, 50% duty ratio, 25% duty ratio based on the proportion of rated current.
Preferably, the small-resistance loop current is controlled by the power device IGBT, and the small-resistance loop current is switched on and off for the one time period; the 100% duty cycle current is the rated current Ie, the rated current at which the 50% duty cycle current is half is 0.5Ie, and the rated current at which the 25% duty cycle current is 1/4 is 0.25Ie.
Preferably, the small-resistance loop current flows through a fault line, and regular current is generated on a current transformer of the fault line;
and when the regular current appears, judging that the loop where the current transformer is located is a fault loop.
Preferably, the magnitude of the regular current is stepped.
Preferably, the arc suppression device further comprises an adjusting unit, wherein the adjusting unit is connected to two sides of the arc suppression coil in parallel and is connected with the control unit.
Compared with the prior art, the utility model has the following beneficial effects:
according to the power distribution network grounding protection control device based on controllable conduction angle, the conduction state of the power device IGBT is changed by controlling the trigger signal of the power device IGBT, so that the current of a small resistance loop is changed, the gradient change condition of zero sequence current of all lines is detected through the gradient change of the current, and the fault loop position is judged;
according to the power distribution network grounding protection control device based on the controllable conduction angle, when a permanent grounding fault occurs and a zero sequence protection error action of a fault line occurs, when the fault is eliminated, the conduction state of the power device IGBT is changed, the current of a resistance loop is reduced, the small resistance circuit is protected, the fault circuit is found to be cut off according to the current law, and the power supply safety and reliability of the power distribution network are guaranteed.
Drawings
Other features, objects and advantages of the present utility model will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
fig. 1 is a schematic structural diagram of a power distribution network ground protection control device based on controllable conduction angle according to an embodiment of the present utility model;
fig. 2 is a waveform diagram of an IGBT in a preferred embodiment of the utility model;
fig. 3 is a regular current diagram of a fault circuit in a preferred embodiment of the present utility model.
Detailed Description
The present utility model will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present utility model, but are not intended to limit the utility model in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present utility model.
The utility model provides an embodiment, a power distribution network ground protection control device based on conduction angle control, and the device participates in fig. 1, and comprises: the system comprises an arc suppression coil, a system neutral point, a small resistor, a power device, a signal acquisition unit and a control unit; one end of the arc suppression coil is grounded; the central point of the system is connected with the other end of the arc suppression coil; the small resistor is connected with the arc suppression coil in parallel; the power device is connected in series with a parallel circuit of the small resistor and the arc suppression coil; the signal acquisition unit acquires parameter signals of the arc suppression coil, a system neutral point and a small resistor; the control unit is connected with the signal acquisition unit and the power device, and receives and controls the triggering or cut-off of the power device according to the parameter signals of the signal acquisition unit.
Typically, the power device is an insulated gate bipolar transistor, insulated Gate Bipolar Transistor, abbreviated IGBT.
According to the embodiment, the on state of the IGBT is changed by controlling the trigger signal of the IGBT of the power device, so that the current of the small-resistance loop is changed, the gradient change condition of the zero sequence current of all lines is detected through the gradient change of the current, the position of the fault loop is judged, the fault line zero sequence protection error action is avoided, and the fault line is directly cut off.
In a preferred embodiment of the utility model, the signal acquisition unit comprises a voltage transformer PT, a current transformer CT and an infrared temperature measurement unit; the voltage transformer PT is connected with a system neutral point, and samples a voltage signal of the voltage transformer PT and inputs the voltage signal into the control unit; the current transformer CT is arranged on a series circuit of a system neutral point and an arc suppression coil, and samples a current signal of the system neutral point and inputs the current signal to the control unit; the infrared temperature measuring unit is connected with the small resistor and samples the temperature signal and sends the temperature signal to the control unit. And the control unit sequentially outputs control pulses with duty ratio regularly changed according to the voltage signals when the voltage signals exceed a set action threshold value, so that the IGBT is conducted, and the regularly changed resistance current characteristic is formed. The control unit monitors the current passing through the arc suppression coil according to the current signal; the control unit monitors the temperature of the small resistor according to the temperature signal, and prevents the burning caused by the overhigh temperature.
In a preferred embodiment of the utility model, the power device IGBT is positioned at the front end of the small resistor, and the current flowing through the small resistor loop is changed in real time by adjusting the triggering angle.
Specifically, when the system operates normally, the arc suppression coil is put into operation, and the small resistor is not put into operation, namely, the power device IGBT of the small resistor loop is disconnected during normal operation. When a single-phase earth fault occurs in the system, the arc suppression coil automatically compensates the capacitance current of the system. If the grounding fault is an instantaneous grounding fault, the grounding is quickly disappeared, the system is restored to a normal running state, and the whole process has small resistance and does not act; if the ground fault does not disappear, it can be determined as a permanent ground fault. At this time, after the time delay t1, namely the time after the permanent ground fault is judged, the time delay time is set to be 0.5 s-2 hours, the current of the small resistance loop is changed by controlling the conduction angle, the input time, namely the IGBT on time is set to be t2, and the time delay time is set to be 0.5 s-2 s, and the fault line is cut off by matching with the relay protection device. At the moment, the system can monitor the running state of the neutral point in real time, if the voltage of the neutral point is recovered to be normal, the action is normal, the fault line is tripped, the control unit automatically cuts off the small resistor, and the system is recovered to the normal running state; if the neutral point voltage is still high, after a certain time (t 2 setting time), the system tripping device is considered to be abnormal, the fault line is not tripped, at the moment, in order to protect the small-resistance device, the control unit controls the conduction angle to reduce the current of the resistance loop, and meanwhile, the tripping abnormality alarms. It should be noted that the relay protection device is a common technical means in the field, and its structure, principle, etc. are not described in detail, and all adopt the conventional arrangement in the prior art.
According to the embodiment, through changing the flowing current of the small-resistance loop in real time, the power supply safety and reliability of the power distribution network can be effectively improved.
In a preferred embodiment of the utility model, the fault circuit is found by regularly changing the current of the small resistance loop, so that the safe and stable operation of the power system is ensured.
Specifically, after a ground fault occurs in the power system, the neutral point voltage increases. Depending on the type of ground, the voltage rise is different, up to the phase voltage. The controller takes the secondary voltage 20V of the voltage transformer as a grounding alarm threshold value, and the controller judges that grounding occurs after exceeding. The partial ground is instantaneous ground, and can automatically disappear, and the resistor is not input at the moment.
After the ground fault occurs, the voltage exceeds a threshold value and the duration exceeds a set value, and the permanent ground is judged, at the moment, the control conduction angle is put into a small resistor, if the zero sequence fault current is large enough, relay protection acts in time, a fault line is cut off, and the ground fault disappears. However, under the condition of high-resistance grounding, the zero-sequence fault current may not reach the fixed value of the relay protection, so that the relay protection cannot act, and at the moment, the system can be used for starting tripping after line protection senses the current with the regular change by changing the conduction angle regularly, so that the safe and stable operation of the power system is ensured.
In a preferred embodiment of the utility model, the regularity of the current comprises: the control unit adopts a variable square wave to control the power device IGBT in real time, and in one period of 20ms, the control unit controls the power device IGBT according to the proportion requirement of rated current and 100% duty ratio, 50% duty ratio and 25% duty ratio. The small-resistance loop current is controlled by the IGBT to control the on-off time of the main loop (the loop consisting of the resistor and the IGBT where the resistor is located) in 1 period of 20ms, so that the 100% duty ratio current is the rated current Ie, the rated current of which 50% duty ratio current is half is 0.5Ie, and the rated current of which 25% duty ratio current is 1/4 is 0.25Ie.
In the field of power systems, the manner of connection and performance characteristics of the small resistance and fault circuit determine that the small resistance loop only flows through the fault circuit. When the current of the small-resistance loop flows through the fault line, regular current is generated on the current transformer of the fault line, referring to fig. 3, the fault loop protection device collects the current signal of the current transformer, and when the regular current occurs, the loop can be judged to be the fault loop.
The embodiment solves the problem that the fault line identification under the condition of high resistance can not be identified in the prior art, and ensures the operation safety of the power system.
In a preferred embodiment of the utility model, the arc suppression device further comprises an adjusting unit, wherein the adjusting unit is connected with the two sides of the arc suppression coil in parallel and is connected with the control unit. The regulating unit changes the inductance of the arc suppression coil, namely the inductive current of the loop. In an electrically operated system, the arc suppression coil is required to provide an inductive current slightly greater than the system capacitance current. Is common knowledge in the art.
In a preferred embodiment of the present utility model, the application process of the power distribution network ground protection control device based on controllable conduction angle in the above embodiment is fully described, and specifically includes the following steps:
step 1: the neutral point of the system is connected with an arc suppression coil, and a voltage transformer PT is used for measuring the neutral point voltage and judging whether single-phase grounding occurs or not;
step 2: the current transformer CT is used for measuring neutral point current and monitoring arc suppression coil loop current;
step 3: the adjusting unit is controlled by the controller XHK-IV and is used for changing the inductance of the arc suppression coil, namely changing the inductive current of the loop;
step 4: the small resistor and the arc suppression coil are connected in parallel with a neutral point of the system, and the small resistor loop current is controlled by the power device IGBT with controllable angle;
step 5: the temperature of the resistor is monitored by an infrared sensor in a contactless way by the small resistor and is sent to the controller XHK-IV;
step 6: the power device IGBT is controlled by the controller XHK-IV, and the conduction angle is controlled along with the temperature change of the small resistor.
The foregoing describes specific embodiments of the present utility model. It is to be understood that the utility model is not limited to the particular embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the claims without affecting the spirit of the utility model. The above-described preferred features may be used in any combination without collision.
Claims (10)
1. The utility model provides a distribution network ground protection controlling means based on conduction angle is controllable which characterized in that includes:
the arc suppression coil is grounded at one end;
the system neutral point is connected to the other end of the arc suppression coil;
the small resistor is connected with the arc suppression coil in parallel;
the power device is connected in series with a parallel circuit of the small resistor and the arc suppression coil;
the signal acquisition unit acquires parameter signals of the arc suppression coil, a system neutral point and a small resistor;
the control unit is connected with the signal acquisition unit and the power device, and is used for receiving and controlling the triggering or cut-off of the power device according to the parameter signals of the signal acquisition unit.
2. The power distribution network grounding protection control device based on the conduction angle controllability as claimed in claim 1, wherein the power device is an insulated gate bipolar transistor, namely Insulated Gate Bipolar Transistor, abbreviated as IGBT.
3. The power distribution network ground protection control device based on controllable conduction angle as claimed in claim 1, wherein the signal acquisition unit comprises:
a voltage transformer, namely Potential Transformer, abbreviated as PT, wherein the voltage transformer PT is connected with the neutral point of the system and samples a voltage signal of the voltage transformer PT to be input into the control unit;
a current transformer, namely Current Transformer, abbreviated as CT, which is arranged on a series circuit of the neutral point of the system and the arc suppression coil, samples a current signal of the neutral point of the system and inputs the current signal to the control unit;
the infrared temperature measuring unit is connected with the small resistor and samples the small resistor to send a temperature signal to the control unit.
4. The power distribution network grounding protection control device based on the controllable conduction angle as claimed in claim 2, wherein the power device IGBT is located at the front end of the small resistor, and the current flowing through the small resistor loop is changed in real time by adjusting the triggering angle of the power device IGBT.
5. The power distribution network grounding protection control device based on the controllable conduction angle as claimed in claim 4, wherein the control unit adopts variable square waves to control the power device IGBT in real time.
6. The device for controlling ground protection of a power distribution network based on controllable conduction angle as claimed in claim 5, wherein said real-time control comprises:
in one time period, control is performed at 100% duty ratio, 50% duty ratio, 25% duty ratio based on the rated current ratio.
7. The controllable-conduction-angle-based power distribution network ground protection control device according to claim 6, wherein the small-resistance loop current is controlled by the power device IGBT, which is turned on and off for the one period of time; wherein, the rated current with 100% duty ratio is the rated current Ie, the rated current with 50% duty ratio is half of the rated current, namely 0.5Ie, and the rated current with 25% duty ratio is 1/4, namely 0.25Ie.
8. The controllable-conduction-angle-based power distribution network ground protection control device according to claim 7, wherein the small-resistance loop current flows through a fault line, and a regular current is generated on a current transformer of the fault line.
9. The power distribution network grounding protection control device based on controllable conduction angle as claimed in claim 8, wherein the magnitude of the regular current is in a step shape.
10. The power distribution network grounding protection control device based on the controllable conduction angle as claimed in claim 1, further comprising an adjusting unit, wherein the adjusting unit is connected to two sides of the arc suppression coil in parallel and connected with the control unit.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202222562893.1U CN219122332U (en) | 2022-09-27 | 2022-09-27 | Power distribution network ground protection control device based on conduction angle is controllable |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222562893.1U CN219122332U (en) | 2022-09-27 | 2022-09-27 | Power distribution network ground protection control device based on conduction angle is controllable |
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| CN202222562893.1U Active CN219122332U (en) | 2022-09-27 | 2022-09-27 | Power distribution network ground protection control device based on conduction angle is controllable |
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