CN110350476B - Selective leakage protection circuit and leakage protection method for low-loss signal conditioning - Google Patents
Selective leakage protection circuit and leakage protection method for low-loss signal conditioning Download PDFInfo
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- CN110350476B CN110350476B CN201910665151.1A CN201910665151A CN110350476B CN 110350476 B CN110350476 B CN 110350476B CN 201910665151 A CN201910665151 A CN 201910665151A CN 110350476 B CN110350476 B CN 110350476B
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- 239000011324 bead Substances 0.000 description 3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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Abstract
The invention relates to a selective leakage protection circuit for signal low-loss conditioning and a leakage protection method, comprising a signal low-loss conditioning circuit, a single-phase electric energy metering circuit, a core processing circuit and an execution circuit which are connected in sequence, wherein zero sequence voltage and zero sequence current are subjected to differential signals obtained by the signal low-loss conditioning circuit, the single-phase electric energy metering circuit calculates a voltage effective value, a current effective value, a power factor and fundamental wave reactive power, and the core processing circuit obtains the zero sequence voltage effective value, the zero sequence current effective value, the power factor and the fundamental wave reactive power and judges whether the zero sequence voltage effective value, the zero sequence current effective value, the power factor and the fundamental wave reactive power exceed set values or not. The signal low-loss conditioning circuit accurately transmits the original analog signal, and the signal information is kept complete; the AD sampling precision of the single-phase electric energy metering circuit is high, the resolution of zero-sequence current and zero-sequence voltage signals is improved, and fault identification is more sensitive; the anti-interference capability is stronger, and the method is suitable for being used in severe environments on site; the electric leakage protection method considers the situation that the power grid is compensated by the arc suppression coil, and has wider application range.
Description
Technical field:
the invention relates to the technical field of coal mine safety, in particular to a selective leakage protection circuit and a leakage protection method for low-loss conditioning of signals of a coal mine safety system.
The background technology is as follows:
the existing selective leakage protection is mainly based on signal characteristics of zero-sequence voltage and zero-sequence current. The signal is characterized in that (1) steady fault signals are weak, the compensated signals are smaller, (2) the signals are greatly influenced by grounding arcs, (3) the signals are greatly influenced by the compensation degree of arc suppression coils, (4) the field interference is large, the signal to noise ratio is small, and (5) the signal amplitude range is wide. Because of the complex signal characteristics, the signal conditioning of the existing selective leakage protection circuit often has the following problems: the filtering depth is too deep, useful transient signals are filtered, the filtering depth is too shallow, and the signal to noise ratio is small; the linear range of the acquisition circuit is narrow, and the signal is incomplete; the peak overvoltage burns out the sampling port; AD accuracy is low and signal resolution is poor.
The invention comprises the following steps:
the invention aims to provide a selective leakage protection circuit and a leakage protection method for low-loss conditioning of signals with small interference, strong signals, high precision and strong signal resolution.
In order to achieve the above objective, the present invention provides a selective leakage protection circuit for low-loss signal conditioning, which includes a low-loss signal conditioning circuit, a single-phase power metering circuit, a core processing circuit and an execution circuit;
the signal low-loss conditioning circuit is used for inhibiting high-frequency interference signals of the zero-sequence voltage and zero-sequence current signal input ports;
the single-phase electric energy metering circuit is electrically connected with the signal low-loss conditioning circuit and is used for processing differential signals in real time, calculating effective voltage values, effective current values, power factors and fundamental reactive power, and storing the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers;
the core processing circuit is electrically connected with the single-phase electric energy metering circuit to realize data interaction and is used for filtering out high-frequency interference of the isolated rear-side data bus, high-frequency interference of the isolated front-side data bus, filtering decoupling of the isolated rear-side power supply and filtering decoupling of the isolated front-side power supply;
the execution circuit is electrically connected with the core processing circuit and is used for outputting signals.
Preferably, the signal low-loss conditioning circuit comprises a current signal low-loss conditioning circuit and a voltage signal low-loss conditioning circuit, and the current signal low-loss conditioning circuit or the voltage signal low-loss conditioning circuit comprises a high-voltage capacitor, a magnetic bead, a bidirectional transient diode, a current transformer, an RC low-pass filter and a filter capacitor which are electrically connected in sequence.
Preferably, the single-phase electric energy metering circuit comprises a single-phase electric energy metering chip, a crystal oscillator oscillation starting capacitor, a metering chip analog power supply filter capacitor, a metering chip digital power supply filter capacitor and a metering chip on-chip reference filter capacitor, wherein the crystal oscillator oscillation starting capacitor, the metering chip analog power supply filter capacitor, the metering chip digital power supply filter capacitor and the metering chip on-chip reference filter capacitor are respectively electrically connected with the single-phase electric energy metering chip.
Wherein, the single-phase electric energy metering chip adopts CS5463.
Preferably, the core processing circuit comprises a CPU, an RC filter circuit, a digital isolator and a filter decoupling capacitor, wherein the CPU is electrically connected with the digital isolator, and an incoming line end and an outgoing line end of the digital isolator are respectively electrically connected with the RC filter circuit and the filter decoupling capacitor.
Wherein, the CPU adopts LPC1768.
Preferably, the execution circuit comprises a CPU, a driving chip, an optocoupler, a relay driving chip, an RC filter circuit and a relay contact arc-extinguishing circuit, wherein the CPU is electrically connected with the driving chip through the RC filter circuit, the driving chip is electrically connected with the relay driving chip through the optocoupler, and the relay driving chip is electrically connected with the relay contact arc-extinguishing circuit.
Wherein, the CPU adopts LPC1768.
The invention also provides a leakage protection method of the selective leakage protection circuit for signal low-loss conditioning, which comprises the following steps:
1. the zero sequence voltage and the zero sequence current respectively pass through the signal low-loss conditioning circuit to obtain differential signals, and the differential signals are respectively connected to corresponding interfaces of the single-phase electric energy metering circuit;
2. the single-phase electric energy metering circuit processes the differential signals in real time, calculates effective voltage values, effective current values, power factors and fundamental reactive power respectively, and stores the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers;
3. the core processing circuit reads a voltage effective value register, a current effective value register, a power factor register and a fundamental wave reactive power register of the single-phase electric energy metering circuit through a data bus to obtain a zero sequence voltage effective value, a zero sequence current effective value, a power factor and a fundamental wave reactive power, and judges whether the set value is exceeded or not;
4. the execution circuit outputs an execution signal.
The third step specifically comprises the following steps:
(1) Initializing a system;
(2) The CPU reads the effective value of the zero sequence voltage, the effective value of the zero sequence current, the power factor and the fundamental reactive power of the single-phase electric energy metering circuit through a data bus, and calculates the phase difference of the process;
(3) Calculating a zero sequence voltage phase difference and a zero sequence current phase difference according to the process phase difference and the fundamental wave reactive power;
(4) Judging whether the effective value of the zero sequence voltage and the effective value of the zero sequence current exceed a set value, returning to the step (2) if the effective value of the zero sequence voltage and the effective value of the zero sequence current do not exceed the set value, and entering the next step if the effective value of the zero sequence voltage and the effective value of the zero sequence current exceed the set value;
(5) And (3) judging whether the zero sequence active power meets the ground protection principle, returning to the step (2) if the zero sequence active power does not exceed the ground protection principle, and outputting an execution signal if the zero sequence active power exceeds a set value.
The invention has the following positive effects:
(1) The signal low-loss conditioning circuit accurately transmits an original analog signal, and signal information is kept complete;
(2) The AD sampling precision of the single-phase electric energy metering circuit is high, the resolution of zero-sequence current and zero-sequence voltage signals is improved, and fault identification is more sensitive;
(3) The anti-interference capability is stronger, and the method is suitable for being used in severe environments on site;
(4) The electric leakage protection method considers the situation that the power grid is compensated by the arc suppression coil, and has wider application range.
Description of the drawings:
FIG. 1 is a schematic diagram of a selective leakage protection circuit for low loss signal conditioning according to the present invention;
FIG. 2 is a schematic circuit diagram of a signal conditioning circuit according to the present invention;
FIG. 3 is a schematic circuit diagram of a single-phase power metering circuit of the present invention;
FIG. 4 is a schematic circuit diagram of a core processing circuit of the present invention;
FIG. 5 is a schematic diagram of a processing method of the core processing circuit of the present invention;
fig. 6 is a schematic circuit diagram of an implementation circuit of the present invention.
The specific embodiment is as follows:
the preferred embodiments of the present invention will be described in detail below with reference to the attached drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
As shown in FIG. 1, the selective leakage protection circuit for low-loss signal conditioning comprises a low-loss signal conditioning circuit, a single-phase power metering circuit, a core processing circuit and an execution circuit.
The signal low-loss conditioning circuit is used for inhibiting high-frequency interference signals of zero-sequence voltage and zero-sequence current signal input ports, as shown in fig. 2, a zero-sequence voltage signal U0 and a zero-sequence current signal I0 are respectively connected into corresponding channels of the signal low-loss conditioning circuit, the two signals are commonly connected to the OCOM, the signal low-loss conditioning circuit comprises a current signal low-loss conditioning circuit and a voltage signal low-loss conditioning circuit, and the current signal low-loss conditioning circuit or the voltage signal low-loss conditioning circuit comprises a high-voltage capacitor, a magnetic bead, a bidirectional transient diode, a current transformer, an RC low-pass filter and a filter capacitor which are electrically connected in sequence.
The high-voltage capacitors C29, C69 and C12 filter high-voltage interference signals, the bidirectional transient diodes D25 and D53 protect zero-sequence voltage and zero-sequence current signal input ports from damaging internal components by strong interference signals, the CT1 and CT2 are high-precision low-phase-shift current transformers for isolating external original signals from internal sampling circuits, the magnetic beads FB3, FB4, FB1 and FB2 inhibit high-frequency interference signals on signal lines, the resistors R59, R64, R92 and R103 respectively form RC low-pass filters with the capacitors C23, C25, C11 and C96 to filter high-frequency signals, the C60 and C97 eliminate differential mode interference in the signals, the D27, D28, D9 and D11 prevent high-voltage burning chip voltage and current ports, the R16, R51, R58 and R101 convert original voltage type signals into current type signals which are connected to the input sides of the current transformers, and the R38, R60, R40, R57, R56 and R61 respectively convert the current type signals output by the current transformers 1 and CT2 into voltage type signals, and then the voltage type signals are output in a differential input mode. The zero sequence voltage and zero sequence current are respectively subjected to a signal low-loss conditioning circuit to obtain differential signals VIN+, VIN-and IIN+ and IIN-. VIN+, VIN-, IIN+ and IIN-are respectively connected to corresponding interfaces of the single-phase electric energy metering circuit.
The ratio of Uo to VIN is a constant valueThe ratio of Io to IIN is a constant value +.>
The single-phase electric energy metering circuit is electrically connected with the signal low-loss conditioning circuit and is used for processing differential signals in real time, calculating effective voltage values, effective current values, power factors and fundamental reactive power, and storing the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers. As shown in fig. 3, the single-phase electric energy metering circuit comprises a single-phase electric energy metering chip, a crystal oscillator oscillation starting capacitor, a metering chip analog power supply filter capacitor, a metering chip digital power supply filter capacitor and a metering chip on-chip reference filter capacitor, wherein the crystal oscillator oscillation starting capacitor, the metering chip analog power supply filter capacitor, the metering chip digital power supply filter capacitor and the metering chip on-chip reference filter capacitor are respectively electrically connected with the single-phase electric energy metering chip.
C83, C85 are crystal oscillator starting capacitors, C76, C77 are analog power supply filter capacitors of the metering chip, C82 is digital power supply filter capacitor of the metering chip, C89 is reference filter capacitor in the metering chip, and the digital ground analog ground of the metering chip is commonly grounded after short circuit.
CS5463 processes differential signals VIN+, VIN-and IIN+ in real time, calculates effective voltage value, effective current value, power factor, fundamental reactive power, and stores into corresponding registers.
The core processing circuit is electrically connected with the single-phase electric energy metering circuit to realize data interaction and is used for filtering out high-frequency interference of the isolated rear-side data bus, high-frequency interference of the isolated front-side data bus, filtering decoupling of the isolated rear-side power supply and filtering decoupling of the isolated front-side power supply. As shown in fig. 4, the core processing circuit includes a CPU, an RC filter circuit, a digital isolator, and a filter decoupling capacitor, where the CPU is electrically connected to the digital isolator, and an incoming terminal and an outgoing terminal of the digital isolator are electrically connected to the RC filter circuit and the filter decoupling capacitor, respectively.
The RC filter circuit formed by R15 and C59 is responsible for filtering and isolating the high-frequency interference of the data bus at the rear side, the capacitors C87 and C21 are the digital isolator U17 for isolating and decoupling the power supply at the rear side, the R88 is the pull-up resistor of the data bus data line, the RC filter circuit formed by R31 and C91 is responsible for filtering and isolating the high-frequency interference of the data bus at the front side, and the capacitors C88 and C95 are the digital isolator U17 for isolating and decoupling the power supply at the rear side.
As shown in fig. 5, the CPU reads the voltage effective value register, the current effective value register, the power factor register, and the fundamental wave reactive power register of CS5463 through the SPI data bus to obtain the zero sequence voltage effective value U rms Zero sequence current effective value I rms The power factor lambda and the fundamental reactive power Q. The zero sequence voltage U is calculated by the following formula 0 The value U of (2) r Value I of zero sequence current Io r And phase difference between them
U rms Ratio to VIN andI rms the ratio to IIN is the constant c=0.25.
Zero sequence voltage U r The calculation formula is that
Zero sequence current I r The calculation formula is that
CPU reads the power factor register and fundamental wave reactive power register to obtain power factor lambda and fundamental wave reactive power Q, and sets the process phase difference asZero sequence voltage and zero sequence current phase difference->The calculation formula is that
When lambda >0
When lambda <0
When Q >0
When Q <0
And judging whether the zero-sequence voltage effective value and the zero-sequence current effective value exceed set values, if the set values are not exceeded, re-reading the zero-sequence voltage effective value, the zero-sequence current effective value, the power factor and the fundamental reactive power, if the set values are exceeded, judging whether the zero-sequence active power meets the ground protection principle, if the ground protection principle is not exceeded, re-reading the zero-sequence voltage effective value, the zero-sequence current effective value, the power factor and the fundamental reactive power, and if the set values are exceeded, executing circuit actions.
The execution circuit is electrically connected with the core processing circuit and is used for outputting signals. As shown in fig. 6, the execution circuit comprises a CPU, a driving chip, an optocoupler, a relay driving chip, an RC filter circuit and a relay contact arc-extinguishing circuit, wherein the CPU is electrically connected with the driving chip through the RC filter circuit, the driving chip is electrically connected with the relay driving chip through the optocoupler, and the relay driving chip is electrically connected with the relay contact arc-extinguishing circuit.
Q8, R1, D1, R4, C2 prevent that chip U1 from exporting by mistake in the power-on in-process, RC filter circuit prevents high frequency interference from constituteing with 26 to R5, and opto-coupler U18 is signal output isolation, and U23 is relay driver chip, and R7, C7 relay contact arc extinction.
The leakage protection method of the selective leakage protection circuit for signal low-loss conditioning comprises the following steps:
1. the zero sequence voltage and the zero sequence current respectively pass through the signal low-loss conditioning circuit to obtain differential signals, and the differential signals are respectively connected to corresponding interfaces of the single-phase electric energy metering circuit;
2. the single-phase electric energy metering circuit processes the differential signals in real time, calculates effective voltage values, effective current values, power factors and fundamental reactive power respectively, and stores the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers;
3. the core processing circuit reads a voltage effective value register, a current effective value register, a power factor register and a fundamental wave reactive power register of the single-phase electric energy metering circuit through a data bus to obtain a zero sequence voltage effective value, a zero sequence current effective value, a power factor and a fundamental wave reactive power, and judges whether the set value is exceeded or not;
4. the execution circuit outputs an execution signal.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.
Claims (5)
1. The selective leakage protection circuit for signal low-loss conditioning comprises a signal low-loss conditioning circuit, a single-phase electric energy metering circuit, a core processing circuit and an executing circuit;
the signal low-loss conditioning circuit is used for inhibiting high-frequency interference signals of the zero-sequence voltage and zero-sequence current signal input ports;
the single-phase electric energy metering circuit is electrically connected with the signal low-loss conditioning circuit and is used for processing differential signals in real time, calculating effective voltage values, effective current values, power factors and fundamental reactive power, and storing the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers;
the core processing circuit is electrically connected with the single-phase electric energy metering circuit to realize data interaction and is used for filtering out high-frequency interference of the isolated rear-side data bus, high-frequency interference of the isolated front-side data bus, filtering decoupling of the isolated rear-side power supply and filtering decoupling of the isolated front-side power supply;
the execution circuit is electrically connected with the core processing circuit and is used for outputting signals;
the leakage protection method is characterized by comprising the following steps of:
1. the zero sequence voltage and the zero sequence current respectively pass through the signal low-loss conditioning circuit to obtain differential signals, and the differential signals are respectively connected to corresponding interfaces of the single-phase electric energy metering circuit;
2. the single-phase electric energy metering circuit processes the differential signals in real time, calculates effective voltage values, effective current values, power factors and fundamental reactive power respectively, and stores the effective voltage values, the effective current values, the power factors and the fundamental reactive power into corresponding registers;
3. the core processing circuit reads a voltage effective value register, a current effective value register, a power factor register and a fundamental wave reactive power register of the single-phase electric energy metering circuit through a data bus to obtain a zero sequence voltage effective value, a zero sequence current effective value, a power factor and a fundamental wave reactive power, and judges whether the set value is exceeded or not;
4. the execution circuit outputs an execution signal;
the third step specifically comprises the following steps:
(1) Initializing a system;
(2) The CPU reads the effective value of the zero sequence voltage, the effective value of the zero sequence current, the power factor and the fundamental reactive power of the single-phase electric energy metering circuit through a data bus, and calculates the phase difference of the process;
(3) Calculating a zero sequence voltage phase difference and a zero sequence current phase difference according to the process phase difference and the fundamental wave reactive power;
(4) Judging whether the effective value of the zero sequence voltage and the effective value of the zero sequence current exceed a set value, returning to the step (2) if the effective value of the zero sequence voltage and the effective value of the zero sequence current do not exceed the set value, and entering the next step if the effective value of the zero sequence voltage and the effective value of the zero sequence current exceed the set value;
(5) And (3) judging whether the zero sequence active power meets the ground protection principle, returning to the step (2) if the zero sequence active power does not exceed the ground protection principle, and outputting an execution signal if the zero sequence active power exceeds a set value.
2. The leakage protection method of a signal low loss conditioned selective leakage protection circuit of claim 1, wherein: the single-phase electric energy metering circuit comprises a single-phase electric energy metering chip, a crystal oscillator starting capacitor, a metering chip analog power supply filter capacitor, a metering chip digital power supply filter capacitor and a metering chip on-chip reference filter capacitor, wherein the crystal oscillator starting capacitor, the metering chip analog power supply filter capacitor, the metering chip digital power supply filter capacitor and the metering chip on-chip reference filter capacitor are respectively electrically connected with the single-phase electric energy metering chip.
3. The leakage protection method of the selective leakage protection circuit for signal low loss conditioning of claim 2, wherein: the single-phase electric energy metering chip adopts CS5463.
4. The leakage protection method of a signal low loss conditioned selective leakage protection circuit of claim 1, wherein: the core processing circuit comprises a CPU, an RC filter circuit, a digital isolator and a filter decoupling capacitor, wherein the CPU is electrically connected with the digital isolator, and an inlet end and an outlet end of the digital isolator are respectively electrically connected with the RC filter circuit and the filter decoupling capacitor.
5. The leakage protection method of a signal low loss conditioned selective leakage protection circuit according to claim 4, wherein: the CPU uses LPC1768.
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