CN210270040U - Interphase short circuit protection device of true experimental system for single-phase earth fault - Google Patents
Interphase short circuit protection device of true experimental system for single-phase earth fault Download PDFInfo
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- CN210270040U CN210270040U CN201920865843.6U CN201920865843U CN210270040U CN 210270040 U CN210270040 U CN 210270040U CN 201920865843 U CN201920865843 U CN 201920865843U CN 210270040 U CN210270040 U CN 210270040U
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Abstract
The utility model discloses a true type experimental system alternate short-circuit protection device of single-phase earth fault, including series connection circuit breaker, drive circuit breaker between single-phase earth fault model and bus action in order to realize drive circuit, the current transformer who gathers three-phase current of interphase short-circuit protection, calculate and differentiate digital signal processor and the power module of line fault type three-phase current, concatenate an operational amplifier circuit between digital signal processor's input and each current transformer respectively, drive circuit's controlled end is connected to digital signal processor's output, and the controlled end of circuit breaker is connected to drive circuit's output. The utility model discloses can enough make relay protection equipment not move when single-phase earth fault experiments, can make relay protection equipment reliably move when taking place alternate short-circuit fault again, on the basis of providing reliable assurance to experimental environment and experimenter's safety, guaranteed going on smoothly of single-phase earth fault experiments.
Description
Technical Field
The utility model relates to a power system trouble real type simulation experiment technical field, especially a protection device that is arranged in single-phase earth fault real type simulation experiment process.
Background
With the continuous acceleration of the construction of power grids, the safe and stable operation of large power grids faces unprecedented challenges, and meanwhile, along with the continuous improvement of the living standard of people, the power supply reliability and the personal safety are more and more widely concerned. The single-phase earth fault is a fault type with the largest occurrence probability in the faults of the power distribution network, and a large number of neutral point earth modes, single-phase earth faults and the like are continuously developed at home and abroad since the beginning of the last century. In order to better research single-phase earth faults, the original computer simulation and low-voltage physical model experiment can not meet the research requirements. A high-voltage true-type experiment platform is vigorously built in national power grids and southern power grids so as to develop a true-type simulation experiment of the single-phase earth fault.
The true experiment inevitably faces the problems of high voltage and large current, and the relay protection is indispensable. When the single-phase earth fault true simulation experiment system operates normally, the current in the three phase lines is basically equal and is a small value; when a single-phase earth fault experiment is carried out, fault current flows in a fault phase, and the magnitude of the fault current depends on the neutral point grounding mode: when the neutral point is grounded by adopting the arc suppression coil, if the arc suppression coil has good compensation, the current in the fault phase can be close to zero; when the neutral point is not grounded, the fault current flowing through the fault phase is equal to the capacitance current to ground of the whole experimental power grid; when the neutral point is grounded through a small resistor, the fault phase current is equal to the sum of the capacitance-to-ground current and the small resistance current of the whole experimental power grid, and the state is generally short-time operation within 5s, but the current value is particularly large.
In the single-phase earth fault carrying process, in order to avoid the occurrence of an inter-phase short-circuit fault from influencing the carrying out of a single-phase earth fault experiment, inter-phase short-circuit relay protection equipment is usually arranged, and the relay protection equipment can avoid the maximum value of single-phase earth fault current so as to ensure the carrying out of a single-phase earth fault true experiment and can also realize the protection of the inter-phase short circuit. In order to ensure the development of a single-phase earth fault true experiment, the protection fixed value of the relay protection equipment is usually set to be larger than the fault current; however, when an inter-phase short circuit occurs in the experimental system, due to the influence of the short circuit loop impedance, the fault current of the two fault phases may be smaller than the small resistance current of the single-phase ground fault, and at this time, the relay protection device cannot be put into protection if the relay protection device does not reach the protection fixed value, so that the smooth operation of the single-phase ground experiment cannot be ensured; if the protection setting value is set to be small, the relay protection device can reliably act when the phase-to-phase fault occurs, and the fault current in the single-phase earth fault experiment process can also trigger the relay protection device to act, so that the single-phase earth fault experiment cannot be normally carried out. Therefore, the conventional relay protection equipment cannot solve the problem of protection when an interphase short circuit occurs in a single-phase earth fault true simulation experiment system, and has great potential safety hazards to experiment environments and experimenters.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that a protection device applied to single-phase earth fault true mode simulation experiment system is provided, can enough guarantee going on smoothly of single-phase earth fault experiment, can carry out effectual protection to the experimental system again when taking place alternate short circuit, provides reliable assurance to experimental environment and experimenter's safety.
In order to solve the technical problem, the utility model adopts the following technical proposal.
The interphase short-circuit protection device comprises a circuit breaker, a driving circuit, a current transformer, a digital signal processor and a power module, wherein the circuit breaker is connected in series between a single-phase earth fault model and a bus, the driving circuit is used for driving the circuit breaker to act so as to realize interphase short-circuit protection, the current transformer is used for collecting three-phase current, the digital signal processor is used for calculating the three-phase current and judging the type of line fault, an operational amplifier circuit is respectively connected in series between the input end of the digital signal processor and each current transformer, the output end of the digital signal processor is connected with the controlled end of the driving circuit, and the output end of the driving circuit is connected with the controlled.
The interphase short-circuit protection device for the true single-phase ground fault experimental system comprises an operational amplifier and an operational amplifier input resistor, wherein a signal end of a current transformer is connected with a positive input end of the operational amplifier through the operational amplifier input resistor, and a filter circuit is connected between a negative input end and an output end of the operational amplifier in series; the output end of the operational amplifier is connected with an analog-to-digital conversion pin of the digital signal processor.
The interphase short circuit protection device of the true single-phase earth fault experimental system comprises a filter resistor and a filter capacitor which are connected in parallel.
The interphase short-circuit protection device for the true single-phase ground fault experimental system comprises a power supply Vcc and a power supply Vkk, wherein the power supply Vcc is used for providing a working power supply for the digital signal processor and the driving circuit, and the power supply Vkk is used for providing a working power supply for the coil of the circuit breaker.
According to the interphase short-circuit protection device for the single-phase earth fault true experimental system, the driving circuit comprises an optical coupling isolation module and an optical coupling matching resistor; the power supply Vcc is connected with the signal output end of the digital signal processor through the optocoupler matching resistor R8, the power supply Vcc is connected with the positive electrode end of the optocoupler isolation module through the optocoupler matching resistor R7, and the negative electrode end of the optocoupler isolation module is connected with the signal output end of the digital signal processor; the power Vkk is connected with the first output end of the optical coupling isolation module, and the second output end of the optical coupling isolation module is grounded through an optical coupling matching resistor R9.
According to the interphase short-circuit protection device for the true single-phase ground fault experimental system, the light emitting diode is connected in series between the power supply Vkk and the first output end of the optical coupling isolation module.
Due to the adoption of the technical scheme, the utility model has the following technical progress.
The utility model simulates the operation characteristics of an experimental system according to the single-phase earth fault true mode, namely, two non-fault phase currents are still small values when the single-phase earth fault experiment is carried out, and the fault phase current can be a large value or even a large value; when the interphase short circuit occurs, at least two phases of currents have larger values as a criterion, the set protection fixed value does not need to avoid single-phase fault current, and the interphase short circuit fault is judged by using a fault phase judgment method, so that the relay protection equipment can not act during a single-phase earth fault experiment, and can reliably act when the interphase short circuit fault occurs, and the smooth operation of the single-phase earth fault experiment is ensured.
Drawings
Fig. 1 is an electrical schematic diagram of the present invention.
Wherein: q1: circuit breakers, CTa, CTb, CTc: current transformers, R1, R3, R5: operational amplifier input resistor, R2, R4, R6: filter resistance, R7, R8, R9: light-blocking matching resistance, C1, C2, C3: filter capacitance, IC 1: operational amplifier, DSP: digital signal processor, OP 1: optoelectronic isolation module, LED: light emitting diode, M1: high-voltage vacuum contactor, Vkk: circuit breaker coil operating voltage, Vcc: a digital signal processor power supply.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
An interphase short-circuit protection device of a single-phase earth fault true experimental system comprises a circuit breaker Q1, current transformers CTa, CTb and CTc, an operational amplifier circuit, a driving circuit, a Digital Signal Processor (DSP) and a power module, wherein the connection relationship among all electrical equipment is shown in figure 1.
The circuit breaker Q1 is connected in series between the single-phase earth fault model and the bus and used for isolating interphase short circuit and ensuring the smooth operation of the single-phase earth fault experiment.
The current transformer CTb is connected in series with the single-phase earth fault model and the breaker Q1, and a high-voltage vacuum contactor M1 is also connected in series between the current transformer CTb and the single-phase earth fault model. The current transformer CTa is connected in series in the A-phase line and collects A-phase current; and the current transformer CTc is connected in series in the C-phase line and acquires the C-phase current.
The operational amplifier circuit is connected in series between the input end of the digital signal processor and the current transformer, and each phase line is provided with an operational amplifier circuit.
The first operational amplifier circuit is connected between the phase current transformer (CTa) and the input end of the AD3 of the digital signal processor in series and comprises an operational amplifier IC-3 and an operational amplifier input resistor R5, the signal end of the current transformer (CTa) is connected with the positive input end of the operational amplifier IC-3 through the operational amplifier input resistor R5, and the output end of the operational amplifier IC-3 is connected with an analog-to-digital conversion pin AD3 of the digital signal processor.
A first filter circuit is connected between the negative input end and the output end of the IC-3 of the operational amplifier in series, and the first filter circuit comprises a filter resistor R6 and a filter capacitor C3 which are connected in parallel.
And a second operational amplifier circuit is connected in series between the phase-B current transformer CTb and the AD2 input end of the digital signal processor and comprises an operational amplifier IC-2 and an operational amplifier input resistor R3, the signal end of the current transformer CTb is connected with the positive input end of the operational amplifier IC-2 through the operational amplifier input resistor R3, and the output end of the operational amplifier IC-2 is connected with an analog-to-digital conversion pin AD2 of the digital signal processor.
And a second filter circuit is connected between the negative input end and the output end of the IC-2 of the operational amplifier in series, and the first filter circuit comprises a filter resistor R4 and a filter capacitor C2 which are connected in parallel.
And a third operational amplifier circuit is connected in series between the C-phase current transformer CTc and the AD1 input end of the digital signal processor and comprises an operational amplifier IC-1 and an operational amplifier input resistor R1, the signal end of the current transformer CTc is connected with the positive input end of the operational amplifier IC-1 through the operational amplifier input resistor R1, and the output end of the operational amplifier IC-1 is connected with an analog-to-digital conversion pin AD1 of the digital signal processor.
And a third filter circuit is connected between the negative input end and the output end of the IC-1 of the operational amplifier in series, and comprises a filter resistor R2 and a filter capacitor C1 which are connected in parallel.
And the digital signal processor DSP is used for calculating three-phase current, calculating the three-phase current, judging the type of the line fault, and driving the circuit breaker to act through the driving circuit according to the calculation result so as to realize the isolation of the interphase short-circuit fault.
The principle of the digital signal processor for judging the line fault is as follows: the protection fixed value is set to be slightly larger than the normal current value, when a single-phase earth fault experiment is carried out, even if the fault phase has large fault current and other two phases are normal current, the calculated sum of the three-phase starting value is smaller than 2, the relay protection equipment cannot act, and the experiment can be normally carried out; but if take place alternate phase short-circuit fault, at least, have great numerical value, even there is great impedance in the fault loop, fault current is not very big, also can surpass the protection definite value, the three-phase starting value that obtains of calculation this moment with equal to 2, just can trigger lower protection definite value, start alternate phase short-circuit fault protection, consequently, both guaranteed single-phase earth fault experiment not influenced, the sensitivity of alternate phase short-circuit fault has been improved greatly again, carry out effectual protection to the experimental system when taking place alternate phase short-circuit, provide reliable assurance to experimental environment and experimenter's safety.
The power module is used for providing working voltage for the digital signal processor and the driving circuit and also providing working voltage for the circuit breaker coil, the working power supply of the digital signal processor and the driving circuit is a power supply Vcc, and the working power supply of the circuit breaker coil is a power supply Vkk.
The driving circuit comprises an optical coupling isolation module OP1 and optical coupling matching resistors R7, R8 and R9. A power supply Vcc of the power supply module is connected with a signal output end GO1 of the digital signal processor through an optocoupler matching resistor R8, the power supply Vcc is connected with a positive electrode end of the optocoupler isolation module through an optocoupler matching resistor R7, and a negative electrode end of the optocoupler isolation module is connected with a signal output end GO1 of the digital signal processor; and controlling the working state of the optical couple isolation module according to the level of the output end of the digital signal processor. The power Vkk of power module connects the first output of opto-isolator module, and the second output of opto-isolator module is through opto-coupler matching resistance R9 ground connection, and power Vkk controls the operating condition of circuit breaker Q1 according to the operating condition of opto-isolator module.
In order to visually represent the working state of the circuit breaker, a Light Emitting Diode (LED) is connected in series between the power supply Vkk and the first output end of the optical coupling isolation module.
The utility model adopts the operational amplifier circuit to carry out low-pass filtering and amplification on the three-phase current signal and then input the three-phase current signal into the analog-to-digital conversion ADC pin of the DSP; the digital signal processor DSP performs sampling integration on the three-phase current signals; comparing the integral result with a set protection fixed value, setting the corresponding starting value to be 1 when the integral result is greater than the set value, and otherwise, resetting; and when the sum of the three-phase starting values is greater than or equal to 2, the inter-phase short-circuit fault is generated, the GO1 port of the digital signal processor DSP outputs a low level, the photoelectric isolation module OP1 is switched on, the high-voltage circuit breaker Q1 is driven to be switched off, and the isolation of the inter-phase short-circuit fault is realized. And when the summation of the three-phase starting values is less than 2, the single-phase earth fault of the experimental system is in normal operation.
Claims (6)
1. The utility model provides a true type experimental system of single-phase earth fault interphase short-circuit protection device which characterized in that: the circuit breaker comprises a circuit breaker (Q1) connected in series between a single-phase earth fault model and a bus, a driving circuit for driving the circuit breaker to act so as to realize inter-phase short circuit protection, current transformers for collecting three-phase current, a Digital Signal Processor (DSP) for calculating the three-phase current and judging the type of line fault, and a power module, wherein an operational amplifier circuit is connected in series between the input end of the DSP and each current transformer, the output end of the DSP is connected with the controlled end of the driving circuit, and the output end of the driving circuit is connected with the controlled end of the circuit breaker.
2. The interphase short-circuit protection device for the true single-phase earth fault experimental system according to claim 1, characterized in that: the operational amplifier circuit comprises an operational amplifier and an operational amplifier input resistor, the signal end of the current transformer is connected with the positive input end of the operational amplifier through the operational amplifier input resistor, and a filter circuit is connected between the negative input end and the output end of the operational amplifier in series; the output end of the operational amplifier is connected with an analog-to-digital conversion pin of the digital signal processor.
3. The interphase short-circuit protection device for the true single-phase earth fault experimental system according to claim 2, characterized in that: the filter circuit comprises a filter resistor and a filter capacitor which are connected in parallel.
4. The interphase short-circuit protection device for the true single-phase earth fault experimental system according to claim 1, characterized in that: the power module includes a power supply Vcc for providing operating power to the digital signal processor and the driver circuit, and a power supply Vkk for providing operating power to the breaker coil.
5. The interphase short-circuit protection device for the true single-phase earth fault experimental system according to claim 4, characterized in that: the driving circuit comprises an optical coupling isolation module (OP1) and an optical coupling matching resistor; the power supply Vcc is connected with a signal output end (GO1) of the digital signal processor through an optocoupler matching resistor R8, the power supply Vcc is connected with a positive end of the optocoupler isolation module through an optocoupler matching resistor R7, and a negative end of the optocoupler isolation module is connected with a signal output end (GO1) of the digital signal processor; the power Vkk is connected with the first output end of the optical coupling isolation module, and the second output end of the optical coupling isolation module is grounded through an optical coupling matching resistor R9.
6. The interphase short-circuit protection device for the true single-phase earth fault experimental system according to claim 5, characterized in that: and a Light Emitting Diode (LED) is connected between the power supply Vkk and the first output end of the optical coupling isolation module in series.
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| CN201920865843.6U CN210270040U (en) | 2019-06-11 | 2019-06-11 | Interphase short circuit protection device of true experimental system for single-phase earth fault |
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| CN201920865843.6U CN210270040U (en) | 2019-06-11 | 2019-06-11 | Interphase short circuit protection device of true experimental system for single-phase earth fault |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110148340A (en) * | 2019-06-11 | 2019-08-20 | 云南电网有限责任公司电力科学研究院 | A kind of true pattern draft experiment phase fault protective device of singlephase earth fault and method |
| CN114002077A (en) * | 2021-11-02 | 2022-02-01 | 国网北京市电力公司 | Electric power test system and method |
-
2019
- 2019-06-11 CN CN201920865843.6U patent/CN210270040U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110148340A (en) * | 2019-06-11 | 2019-08-20 | 云南电网有限责任公司电力科学研究院 | A kind of true pattern draft experiment phase fault protective device of singlephase earth fault and method |
| CN110148340B (en) * | 2019-06-11 | 2021-06-11 | 云南电网有限责任公司电力科学研究院 | Single-phase earth fault true mode simulation experiment interphase short circuit protection device and method |
| CN114002077A (en) * | 2021-11-02 | 2022-02-01 | 国网北京市电力公司 | Electric power test system and method |
| CN114002077B (en) * | 2021-11-02 | 2023-11-17 | 国网北京市电力公司 | Electric power test system and method |
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Effective date of registration: 20200904 Address after: Yunda economic and Technological Development Zone in Yunnan province Kunming city 650217 West Road No. 105 Patentee after: YUNNAN POWER GRID CO., LTD. ELECTRIC POWER Research Institute Address before: Yunda economic and Technological Development Zone in Yunnan province Kunming City 650000 West Road No. 105 Co-patentee before: HEBEI XUHUI ELECTRIC Co.,Ltd. Patentee before: YUNNAN POWER GRID CO., LTD. ELECTRIC POWER Research Institute |
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