CN102684141B - Shock current identifying method and aftercurrent protecting device - Google Patents
Shock current identifying method and aftercurrent protecting device Download PDFInfo
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- CN102684141B CN102684141B CN201210134823.4A CN201210134823A CN102684141B CN 102684141 B CN102684141 B CN 102684141B CN 201210134823 A CN201210134823 A CN 201210134823A CN 102684141 B CN102684141 B CN 102684141B
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Abstract
The invention discloses a shock current separating method, and relates to the field of electrical engineering technology. The shock current separating method includes the steps: S1, performing wavelet multi-resolution decomposition and reconstruction on the total leaked current acquired by means of real-time monitoring and acquiring the reconstructed low frequency signal; and S2, acquiring M periodic low frequency signals as current operating windows, sequentially moving the current operating windows, using the difference between the rear M/2 periodic low frequency signals and the front M/2 periodic low frequency signals as a separating current for separating, and wherein the M is an even number. By the aid of the shock current separating method shock current can be accurately separated from the total leaked current by means of sliding windows and based on wavelet, whether tripping is needed or not can be judged according to the amplitude of the shock current, problems that whether tripping is needed or not is judged by the total leaked current can cause misoperation and non-operation are avoided.
Description
Technical field
The present invention relates to electrical engineering technical field, particularly a kind of method for protecting residual current and device.
Background technology
Aftercurrent protecting equipment prevents the person from getting an electric shock and avoiding causing the important roles such as electric equipment damage because of leakage current in rural low voltage network.At present conventional Aftercurrent protecting equipment has amplitude discrimination formula and amplitude discrimination phase discriminator type two class, and the amplitude of its operating criterion normally total leakage current in low-voltage power supply loop is greater than certain setting value, or the Tiny increment dt of total leakage current is greater than certain setting.Operating experience shows, current Aftercurrent protecting equipment mostly cannot the current signal of real identification human electric shock branch road, close when usually there is large load not brake application, cannot correctly put into operation; Or under wet weather condition, because electric loop insulation level significantly reduces, cause earth leakage current to increase, and then occur the phenomenon of misoperation.Its main cause is, electrical shock protective device does not really distinguish normal leakage electric current and human electric shock's electric current in principle.
Summary of the invention
(1) technical problem that will solve
The technical problem to be solved in the present invention is: how to distinguish normal leakage electric current and shock current exactly.
(2) technical scheme
For solving the problems of the technologies described above, the invention provides a kind of shock current separation method, comprising the following steps:
S1: the total leakage current real-time monitored is carried out to Wavelet Multi-resolution Transform and reconstructs, obtains the low frequency signal after reconstructing;
S2: to the described low frequency signal in M cycle as current operation window, move described window successively, using the difference of a rear M/2 cycle and the low frequency signal in a front M/2 cycle as the shock current be separated, M is even number.
Wherein, the db11 morther wavelet in Daubechies system is adopted to carry out Wavelet Multi-resolution Transform to the total leakage current real-time monitored in step S1.
Wherein, in described step S1, carry out Wavelet Multi-resolution Transform, decomposition scale is 6.
Wherein, described M is 8.
Wherein, when moving described window successively, each mobile 1 cycle.
Present invention also offers a kind of Aftercurrent protecting equipment; comprise: single chip circuit and executive circuit; described single chip circuit is used for from the total leakage current received, isolating shock current by the shock current separation method described in above-mentioned any one, and sends tripping operation execution instruction when described shock current amplitude exceedes specified operating value to described executive circuit.
Wherein, described single chip circuit detects that continuous moving window three isolated shock currents send tripping operation to described executive circuit when all exceeding described specified operating value and perform instruction.
Wherein, also comprise mode configuration circuit, connect described single chip circuit, for configuring the mode of operation of described single-chip microcomputer.
Wherein, also comprise: the display circuit for display parameters be connected with described single chip circuit.
Wherein, also comprise: be connected with described single chip circuit for the communication interface circuit with compunication.
(3) beneficial effect
The present invention isolates shock current by achieving based on small echo and sliding window mode exactly from total leakage current; and judge whether to need tripping operation according to the amplitude of this shock current, avoid and judge whether to trip according to total leakage current size and the problem of the protective device malfunction that causes or tripping.
Accompanying drawing explanation
Fig. 1 is a kind of shock current separation method flow chart of the embodiment of the present invention;
Fig. 2 is a kind of Aftercurrent protecting equipment structural representation of the embodiment of the present invention;
Fig. 3 is the device workflow schematic diagram in Fig. 2.
Embodiment
Below in conjunction with drawings and Examples, the specific embodiment of the present invention is described in further detail.Following examples for illustration of the present invention, but are not used for limiting the scope of the invention.
Shock current separation method idiographic flow provided by the invention as shown in Figure 1, comprising:
Step S1, carries out Wavelet Multi-resolution Transform to the total leakage current real-time monitored, and obtains the low frequency signal after reconstructing.Db11 morther wavelet in concrete employing Daubechies system is to the total leakage current real-time monitored
carry out Wavelet Multi-resolution Transform, decomposition scale is selected to be 6 to decompose, low frequency signal effectively can be retained like this, again can denoising effectively (removing high-frequency signal), and due to the fault oscillograph sample frequency used in electric shock Physical Experiment platform be 10000Hz, in order to the requirement making the signal of reconstruct meet 50Hz, therefore, to original total leakage current
proceed to many 6 layers of decomposition.By a large amount of experimental verifications, morther wavelet selects the female ripple of the db11 in Daubechies system.
Step S2, to the data in M cycle as current operation window, moving window successively, window is moved forward one-period, the data in a rear M/2 cycle and the difference in a front M/2 cycle are as the signal identified, and carry out error analysis and similarity analysis with actual test value, and then isolate shock current.Wherein, the value of M is relevant with the operate time of Aftercurrent protecting equipment.Usually require this operate time to be less than or equal to 0.1 second, therefore, M is desirable
in the data in 8 cycles as current operation window, 8 cycles can reflected waveform state completely, can meet requirement operate time again.Move computing window successively, owing to describing a signal in time-domain, its base unit is one-period, and in order to ensure the precision of isolated shock current, every less preferred movement is spaced apart 1 cycle.In current window, by the difference of rear 4 cycles and front 4 cycle low frequency signals as shock current, and then isolate shock current.The normal leakage current of electrical network and power consumption equipment changes along with the change of time, but its change is slowly.From a stable state to another stable state, the transformation period of leakage current may be several seconds, somewhat, or even several hours, the leakage current causing the change etc. of insulation resistance to cause as changed due to the humidity of air changes.Most of fault leakage current then at several cycle, or even can have greatly changed in several milliseconds, as person electric shock etc., therefore can isolate shock current exactly as stated above.
Present invention also offers a kind of Aftercurrent protecting equipment utilizing said method to realize; this device is achieved by said method and isolate shock current exactly from total leakage current; and the amplitude of this shock current judges whether to need tripping operation, avoid and judge whether to trip according to total leakage current size and the problem of the protective device malfunction that causes or tripping.As shown in Figure 2, this device comprises concrete structure schematic diagram:
The zero sequence current mutual inductor of the total leakage current of signal conditioning circuit, single chip circuit, executive circuit, power circuit and Real-Time Monitoring.Single chip circuit is the core of this invention, is responsible for processing image data, isolates shock current, controls the operation of executive circuit, reaches protected effect.Single chip circuit specifically comprises: reconfiguration unit and separative element.Reconfiguration unit is used for the total leakage current real-time monitored is carried out to Wavelet Multi-resolution Transform and reconstructs, and obtains the low frequency signal after reconstructing; Separative element, for the described low frequency signal in M cycle as current operation window, move described window successively, using the difference of a rear M/2 cycle and the low frequency signal in a front M/2 cycle as the shock current be separated, M is even number.
Particularly, zero sequence current mutual inductor passes A, B, C phase line and the neutral line of distribution line, and the output of zero sequence current mutual inductor is connected with signal conditioning circuit input; Signal conditioning circuit output is connected in single chip circuit, and the analog signal of instrument transformer is converted to digital signal and sends in single chip circuit by signal conditioning circuit timesharing; Single chip circuit record has collected data, and adopts above-mentioned small echo to isolate shock current in conjunction with the decomposition algorithm of sliding window from total leakage current with this; Finally; the action foundation of single-chip microcomputer using shock current as device, performing instruction by sending tripping operation to coupled executive circuit, realizing tripping operation; avoid the tripping of existing Aftercurrent protecting equipment existence, malfunction problem, improve protective device reliability of operation.
The time requirement that performs an action of the executive circuit of this device is less than or equal to 0.1 second, and namely must complete trip protection action in rear 5 cycles of electric shock, therefore, M gets
in the data in 8 cycles as current operation window, successively moving window, be mobilely spaced apart 1 cycle at every turn.In current window, by the difference of rear 4 cycles and front 4 cycle low frequency signals as the signal identified, and carry out error analysis and similarity analysis with actual test value, and then isolate the amplitude of shock current.
In order to improve the reliability of algorithm, the present invention is provided with a flag bit Flag in the program of single chip circuit, Flag initial value is 0, only have when three cycles, isolated shock current all exceeded specified operating value to continuous moving, namely when Flag equals 3, just can be defined as electric shock accidents, doing so avoids the misoperation that some sampling errors due to test macro may cause.
Further, Aftercurrent protecting equipment of the present invention still remains existing mode of operation, and namely this Aftercurrent protecting equipment is provided with two kinds of mode of operations, and one is general mode, and one is divergence type pattern.General mode, the i.e. function of traditional residual current protective device, when being chosen as this pattern, the rated current default setting of system is 30mA, works as residual current
when size is more than 30mA, equipment is by action.Divergence type pattern, namely send the new model of trip command according to the amplitude of shock current, device identifies shock current and makes protection act according to corresponding criterion.The mode of operation of device acquiescence is divergence type.And under some special environment, as: bathroom, the operating current of this device more generally should be less, therefore needs to be configured desired action current and operate time.
In order to realize mode of operation and the configuration of desired action current and operate time, this device also comprises: the mode configuration circuit connecting single chip circuit, as the keyboard circuit in Fig. 2, user is by keyboard associative operation, mode of operation is set, corresponding desired action current and operate time are set.This function can improve the stability and adaptability of this cover system.
Further, in order to realize better man-machine interaction, this device also comprises display circuit, as liquid crystal display etc., current value and magnitude of voltage, the shock current value identified of the residual current of actual measurement can be shown at display screen, whether get an electric shock, Working mode set, setting value setting etc.And three-phase current, zero-sequence current 4 road current signal are measured to three-phase and four-line electric power system, three-phase voltage and residual voltage 4 road signal, and isolated shock current signal is shown, real-time storage selectes the signal waveform data of period.
Further, this device also comprises communication interface circuit, as: serial ports, by serial ports, sampling data transmitting is delivered to PC, be convenient to do to analyze further to sampled data.
The fractional hardware equipment that Aftercurrent protecting equipment of the present invention adopts is as follows:
Chip L7805CV and the LM1117 of power circuit is adjustable three terminal regulator.Ui is the 9V voltage after AC/DC conversion, after L7805CV and LM1117 conversion, 5V and 3.3V galvanic current pressure is obtained respectively at VDD and VCC place, both meet the module such as serial communication, relay output to the requirement of power supply, and also can provide power supply for single chip circuit and liquid crystal display, serial storage module.
Signal conditioning circuit comprises signal altogether and amplifies and filter circuit two parts, and the chip selected is the precision operational-amplifier OPA4374 that Texas Instrument produces, and this amplifier input bias current is 10pA, and input offset voltage is 5mV, adopts single power supply.
Single chip circuit selects the MSP430F149 into American TI Company, this chip internal is containing 2kBRAM district, can be used for quick storage sampled data, under the driving of 8MHz crystal, realize the instruction cycle of 125ns, carry 12 analog-to-digital conversion modules (ADC12), can realize the analog-to-digital conversion of 12 precision, sample rate reaches as high as 200kbps.
The chip that liquid crystal display circuit adopts is the disassembling graph liquid crystal display YLF12232 that Beijing You Lifa scientific & trading Co., Ltd. produces.
As shown in Figure 3, be Aftercurrent protecting equipment workflow diagram of the present invention, this device enters system initialization after the power-up; After the initialization of modules completes smoothly, enter the main program cycle in single chip circuit, the mode of operation of system is determined by the associative operation of button, acquiescence be divergence type pattern.When being chosen as divergence type pattern, system will enter data acquisition, data processing, separation algorithm supervisor, finally isolate shock current amplitude; When shock current is less than the operating value of setting, continue the circulation of main program; When shock current is greater than the operating value of setting, system sends trip command, end loop.When being chosen as general modfel, the operation principle of Aftercurrent protecting equipment is conveniently run by system, and when residual current is more than 30mA, system sends trip command, end loop, otherwise, then continue the circulation of main program.The shock current amplitude that above button operation, the leakage current of surveying and sub-argument go out and device action situation, can pass through liquid crystal display program, show in LCDs.
Above execution mode is only for illustration of the present invention; and be not limitation of the present invention; the those of ordinary skill of relevant technical field; without departing from the spirit and scope of the present invention; can also make a variety of changes and modification; therefore all equivalent technical schemes also belong to category of the present invention, and scope of patent protection of the present invention should be defined by the claims.
Claims (5)
1. a shock current separation method, is characterized in that, comprises the following steps:
S1: the total leakage current real-time monitored is carried out to Wavelet Multi-resolution Transform and reconstructs, obtains the low frequency signal after reconstructing;
S2: to the described low frequency signal in M cycle as current operation window, move described window successively, and when moving described window successively, 1 cycle of each movement, using the difference of a rear M/2 cycle and the low frequency signal in a front M/2 cycle as the shock current be separated, M is even number, and wherein, described M is 8; Described M value is relevant with the operate time of Aftercurrent protecting equipment; Require described operate time to be less than or equal to 0.1 second;
Wherein, in current window, by the difference of rear 4 cycles and front 4 cycle low frequency signals as shock current, and then isolate shock current;
Wherein, the db11 morther wavelet in Daubechies system is adopted to carry out Wavelet Multi-resolution Transform to the total leakage current real-time monitored in step S1;
Wherein, in described step S1, carry out Wavelet Multi-resolution Transform, decomposition scale is 6.
2. an Aftercurrent protecting equipment, comprise: single chip circuit and executive circuit, it is characterized in that, described single chip circuit is used for from the total leakage current received, isolating shock current by shock current separation method according to claim 1, and sends tripping operation execution instruction when described shock current amplitude exceedes specified operating value to described executive circuit;
Wherein, described single chip circuit detects that continuous moving window three isolated shock currents send tripping operation to described executive circuit when all exceeding described specified operating value and perform instruction;
Wherein, in the program of single chip circuit, be provided with a flag bit Flag, Flag initial value is 0, only has when three cycles, isolated shock current all exceeded specified operating value to continuous moving, when namely Flag equals 3, just can be defined as electric shock accidents.
3. Aftercurrent protecting equipment as claimed in claim 2, is characterized in that, also comprise mode configuration circuit, connect described single chip circuit, for configuring the mode of operation of described single-chip microcomputer.
4. Aftercurrent protecting equipment as claimed in claim 2, is characterized in that, also comprise: the display circuit for display parameters be connected with described single chip circuit.
5. Aftercurrent protecting equipment as claimed in claim 2, is characterized in that, also comprise: be connected with described single chip circuit for the communication interface circuit with compunication.
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| CN201210134823.4A CN102684141B (en) | 2012-04-28 | 2012-04-28 | Shock current identifying method and aftercurrent protecting device |
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| CN201210134823.4A CN102684141B (en) | 2012-04-28 | 2012-04-28 | Shock current identifying method and aftercurrent protecting device |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102904209A (en) * | 2012-11-01 | 2013-01-30 | 四川省电力公司资阳公司 | Digital signal processing (DSP)-based current separation motion type electric leakage protection device and method |
| CN103825245B (en) * | 2014-01-27 | 2018-01-16 | 广东南冠电气有限公司 | It is a kind of to distinguish the intelligent breaker to get an electric shock with electric leakage signal |
| CN104638612B (en) * | 2015-02-13 | 2017-08-08 | 西安交通大学 | A kind of human electric shock's identification of accidental events and guard method |
| CN105956242B (en) * | 2016-04-25 | 2019-10-08 | 中国农业大学 | The multiport impedance model construction method calculated based on organism electric shock impedance parameter |
| CN107276029B (en) * | 2017-06-20 | 2019-04-16 | 安徽南瑞继远电网技术有限公司 | Anti- personal electrical shock circuit breaker control method and system based on Waveform Identification Technology |
| CN112906389B (en) * | 2021-02-04 | 2022-08-26 | 云南电网有限责任公司昆明供电局 | Fault trip discrimination method based on multi-dimensional data analysis |
| CN112952753B (en) * | 2021-03-15 | 2024-05-10 | 国网福建省电力有限公司南平供电公司 | Threshold self-adaptive adjustment-based electric shock accident detection method and system for low-voltage power network |
| CN113325028B (en) * | 2021-06-07 | 2022-05-24 | 中国核动力研究设计院 | Boiling critical experiment device for unstable flow of natural circulation system and control method |
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