CN110609192A - Low-voltage primary power system parameter acquisition system - Google Patents
Low-voltage primary power system parameter acquisition system Download PDFInfo
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Abstract
The invention relates to power system parameter detection, in particular to a low-voltage primary power system parameter acquisition system, which is characterized in that: at least comprises the following steps: a sensing detection unit and a signal processing unit; the sensing detection unit is electrically connected with the signal processing unit; the sensing detection unit is used for acquiring current signals of three-phase voltage through a current transformer and acquiring voltage signals of the three-phase voltage through a voltage transformer; the current processing interface is used for filtering the acquired current signals of the three-phase voltage and transmitting the filtered current signals to the signal processing unit; the voltage processing interface is used for carrying out high-voltage isolation on the acquired current signals of the three-phase voltage and transmitting the current signals to the signal processing unit; the signal processing unit is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current. The method brings a more concise and practical method for wiring of a large number of low-voltage cabinets at present.
Description
Technical Field
The invention relates to parameter detection of a power system, in particular to a low-voltage primary power system parameter acquisition system.
Technical Field
At present, with the rapid development of the electric power automation technology, the measurement of electrical parameters (current and voltage) basically eliminates the measurement of the traditional pointer instrument and is changed into an electronic instrument for measurement. In the traditional power system, the extraction of current and voltage parameters is transmitted by the required parameters of a primary meter to a secondary meter. The primary current transformation is to change the alternating current of more than 0-100A into the grade of less than 0-5A through the current transformer. The primary high voltage conversion is to firstly change the high voltage grade of more than 110KV into the grade of less than 10kV (such as 0.38KV, 0.22KV and the like) through a high voltage transformer. When the electrical parameters are changed into secondary current of 0-5A or 0-1A and secondary voltage of 380V grade through a plurality of primary devices, the secondary instruments can be measured.
In the practical application of a low-voltage (0.38 kV grade) power system, the current is collected by firstly passing a primary current through a current converter to be converted into a secondary current below 0-5A, then connecting the secondary current to an instrument through a plurality of external wiring modes, converting the secondary current into milliampere grade current required by a sampling loop through a small-sized current transformer inside the instrument, and finally providing the milliampere grade current for the current collection loop through an I/V conversion circuit to realize the measurement of power parameter current. The voltage acquisition is realized by converting high voltage (0.38 kV) into mV level through a voltage transformer and providing the mV level for a voltage acquisition loop to realize the measurement of voltage parameters.
In the above conventional (low voltage) power parameter extraction scheme, three drawbacks are evident.
1. Two-stage current-voltage conversion is needed, a plurality of external connecting wires are needed between the two-stage conversion, and the material cost and the labor cost are high.
2. The number of leads is large from the first time to the second time, the leads are long, and the mutual electromagnetic interference is large.
3. When the secondary measuring instrument is used for precision calibration, calibration needs to be carried out on a secondary current rated value required by a current transformer applied at the current input end of the instrument, and the error (superposition of a plurality of influence links) of current measurement is often very large because the problems of mutual interference of leads from primary to secondary, consistency of a plurality of current transformers and the like cannot be eliminated.
Disclosure of Invention
The invention aims to provide a low-voltage primary power system parameter acquisition system, in particular to a low-voltage power system parameter measurement system which adopts one-time fusion (conversion) to change required power parameters into universal digital signals through a special mutual inductor and a special circuit board for output. A more concise and practical method is brought to the wiring of a large number of low-voltage cabinets at present.
The invention aims to realize the method, and the system for acquiring the parameters of the low-voltage primary power system is characterized in that: at least comprises the following steps: a sensing detection unit and a signal processing unit; the sensing detection unit is electrically connected with the signal processing unit;
the sensing detection unit is used for acquiring current signals of three-phase voltage through a current transformer and acquiring voltage signals of the three-phase voltage through a voltage transformer;
the current processing interface is used for filtering the acquired current signals of the three-phase voltage and transmitting the filtered current signals to the signal processing unit;
the voltage processing interface is used for carrying out high-voltage isolation on the acquired current signals of the three-phase voltage and transmitting the current signals to the signal processing unit;
the signal processing unit is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain effective values of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current, effective values of the ABC three-phase full-wave voltage, phase-closing active power, phase-closing reactive power, apparent power and phase-closing REMS power factors;
the signal processing unit is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain power parameters such as voltage frequency, active positive power, active reactive power, reactive positive power, reactive power, total current harmonic content, total voltage harmonic content and 1-order to 50-order voltage harmonic component of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current.
The sensing unit includes: the first primary current feedthrough mutual inductor, the second primary current feedthrough mutual inductor and the third primary current feedthrough mutual inductor are primary current feedthrough mutual inductors and are respectively sleeved on an A \ B \ C three-phase power supply circuit to acquire current information of the three-phase circuit and realize electrical isolation from current sensing to current signal processing.
The transformation ratio of the first primary current feedthrough transformer, the second primary current feedthrough transformer and the third primary current feedthrough transformer is 10000:1, and the transformers are used for converting a large current of more than 0-100A into a mA-level small current for output; the first primary current feedthrough transformer, the second primary current feedthrough transformer and the third primary current feedthrough transformer are respectively and electrically connected with a three-phase power supply current sampling filter circuit; the three-phase power supply current sampling filter circuit is used for converting a first primary current feedthrough transformer, a second primary current feedthrough transformer and a third primary current feedthrough transformer into voltage signals through a current sampling and current filtering I/V circuit and connecting the voltage signals to a subsequent processing circuit.
The signal processing unit acquires current and voltage signals in the three-phase voltage A, B, C, and the signal processing unit respectively carries out differential processing on the acquired current signal and voltage signal in the three-phase voltage A, B, C and the current signal and voltage signal which are sent to the current differential A/D input circuit and the voltage differential A/D input circuit; signals subjected to differential processing by the current differential A/D input circuit and the voltage differential A/D input circuit are sent to an ARM processor through a simulation interface circuit, and are processed by the ARM processor to obtain effective values of ABC three-phase full-wave voltage and ABC three-phase full-wave current, effective values of ABC three-phase full-wave voltage, combined-phase active power, combined-phase reactive power, apparent power and combined-phase REMS power factors; the power parameter information of voltage frequency, active positive power, active reverse power, reactive positive power, reactive reverse power, total current harmonic content, total voltage harmonic content, 1-50 voltage harmonic components and the like of the ABC three-phase full-wave current; the ARM processor divides the processed information into two paths, one path is stored in the RAM memory, and the other path is transmitted to the interface circuit through the digital isolation interface circuit; the interface circuit is 485 interface, CAN interface, SPI interface, UART interface, or/and their combination or split-combination.
The signal processing unit acquires current and voltage signals in the three-phase voltage A, B, C, and respectively sends the acquired current and voltage signals in the three-phase voltage A, B, C to the integrated processing circuit for processing; the signal processed by the integrated processing circuit is sent to an ARM processor through an analog interface circuit, and is processed by the ARM processor to obtain ABC three-phase full-wave voltage, an effective value of ABC three-phase full-wave current, an effective value of ABC three-phase full-wave voltage, phase-combining active power, phase-combining reactive power, apparent power and a phase-combining REMS power factor; the ABC three-phase full-wave current comprises power parameter information such as voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content, 1-order to 50-order voltage harmonic components and the like.
The signal processing unit includes: the system comprises an ARM processor, an RAM memory, a digital isolation interface circuit, an interface circuit, a current differential A/D input circuit and a voltage differential A/D input circuit; the current differential A/D input circuit and the voltage differential A/D input circuit are respectively electrically connected with the ARM processor, and the ARM processor is electrically connected with the RAM memory through a bus interface; the ARM processor is electrically connected with the interface circuit through the digital isolation interface circuit.
The signal processing unit includes: ARM processor, RAM memory, digital isolation interface circuit, integrated processing circuit; the input end of the integrated processing circuit is electrically connected with the first primary current feedthrough transformer, the second primary current feedthrough transformer and the third primary current feedthrough transformer respectively, the output end of the integrated processing circuit is electrically connected with the ARM processor, and the ARM processor is electrically connected with the RAM memory through a bus interface; the ARM processor is electrically connected with the interface circuit through the digital isolation interface circuit.
The ARM processor acquires ABC three-phase full-wave voltage and ABC three-phase full-wave current information, firstly, digital filtering is carried out on A-phase voltage, A-phase current, B-phase voltage, B-phase current, C-phase voltage and C-phase current respectively, and digital signals of the filtered A-phase voltage, A-phase current, B-phase voltage, B-phase current, C-phase voltage and C-phase current are obtained;
calculating the effective value of the phase voltage current of the A phase according to the information obtained by the phase voltage of the A phase and the phase current of the A phase;
calculating the effective value of the B-phase voltage current according to the information obtained by the B-phase voltage and the B-phase current;
calculating the effective value of the C-phase voltage current according to the information obtained by the C-phase voltage and the C-phase current;
calculating the active power and the reactive power of the phase A through the effective value of the phase voltage current of the phase A;
calculating the active power and the reactive power of the phase B through the effective value of the phase B voltage current;
calculating the active power and the reactive power of the C phase through the effective value of the C phase voltage current;
calculating the phase-combining active power, the phase-combining reactive power, the apparent power and the phase-combining REMS power factor according to the parameters; voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content and 1 to 50 times of voltage harmonic component information of ABC three-phase full-wave current;
storing said information in a RAM memory;
and sending the information to the interface circuit according to the command.
The integrated processing circuit is an ADE7758 series, an ATT7022 series and an RN7302 series, and after the processing of synchronous acquisition and filtering and the like in the integrated processing circuit, the ARM processor exchanges data with the metering chip through the SPI interface; the ARM processor obtains harmonic components of more than 50 times of voltage and current by performing real-time FFT operation on the 3 paths of voltage and the 3 paths of current.
The invention has the advantages that:
1. the low-voltage primary transformation is adopted, a current voltage transformer of the original low-voltage cabinet is omitted, the space in the cabinet is saved, and the material cost is reduced.
2. And by adopting a digital bus (485, CAN) interface, all low-voltage power parameters CAN be transmitted to a centralized display unit and a communication management unit of the low-voltage cabinet.
3. The number of the leads and the wire diameter of the leads are reduced, and the manual installation cost is reduced.
4. The calibration accuracy of the instrument is improved.
5. The maintenance is convenient.
The invention adopts a primary power conversion technology, not only solves the problems of cost, wiring, long-distance transmission and reliability of the secondary conversion of the traditional power system, but also has the advantage of realizing multi-path data sharing through a digital interface at present of digitalization of an intelligent instrument.
Drawings
The invention is further illustrated with reference to the accompanying drawings of embodiments:
FIG. 1 is a schematic diagram of a current and voltage signal acquisition circuit according to an embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of embodiment 1 of the present invention;
FIG. 3 is a schematic circuit diagram according to embodiment 2 of the present invention;
FIG. 4 is a flow chart of processing circuitry according to an embodiment of the present invention.
In the figure, 1, a sensing unit; 2. a signal processing unit; 3. a three-phase power supply current sampling filter circuit; 4. a three-phase voltage primary extraction circuit; 5. an integrated processing circuit; 6. a digital isolation interface circuit; 7. an interface circuit; 8. a RAM memory; 9-1, a current differential A/D input circuit; 9-2, a voltage differential A/D input circuit; 10. an ARM processor.
Detailed Description
Example 1
As shown in fig. 1 and 2, a low-voltage primary power system parameter acquiring system at least includes: a sensing detection unit 1 and a signal processing unit 2;
the sensing detection unit 1 is used for acquiring current signals of three-phase voltage through a current transformer and acquiring voltage signals of the three-phase voltage through a voltage transformer;
the current processing interface is used for filtering the acquired current signals of the three-phase voltage and transmitting the filtered current signals to the signal processing unit 2;
the voltage processing interface is used for carrying out high-voltage isolation on the acquired current signals of the three-phase voltage and transmitting the current signals to the signal processing unit 2;
the signal processing unit 2 is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain effective values of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current, effective values of the ABC three-phase full-wave voltage, phase-closing active power, phase-closing reactive power, apparent power and phase-closing REMS power factors;
the signal processing unit 2 is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain the voltage frequency, the active positive power, the active negative power, the reactive positive power, the reactive negative power, the total harmonic content of the current, the total harmonic content of the voltage, the 1 st to 50 th order voltage harmonic component and other power parameters of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current.
In fig. 1, a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 are primary current feedthrough transformers, which are respectively sleeved on an a \ B \ C three-phase power circuit loop to obtain current information of the three-phase loop and simultaneously realize electrical isolation from current sensing to current signal processing. The first primary current feedthrough transformer 1.1, the second primary current feedthrough transformer 1.2 and the third primary current feedthrough transformer 1.3 are respectively and electrically connected with a three-phase power supply current sampling filter circuit 3.
In the figure 1, the transformation ratio of a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 is 10000:1, and the transformers are used for converting a large current of more than 0-100A into a mA-level small current for output.
The three-phase voltage primary extraction circuit 4 in fig. 1 is used for directly converting primary voltage in ABC three-phase voltage into mA-level current through a voltage transformer, obtaining mV-level voltage output through high-voltage isolation conversion, and connecting the mV-level voltage output to a subsequent processing circuit.
The three-phase power supply current sampling filter circuit 3 in fig. 1 is used for converting a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 into voltage signals through a current sampling and current filtering I/V circuit, and connecting the voltage signals to a subsequent processing circuit.
The voltage transformer and the current transformer are wound by high-strength high-transformation-ratio coils and are encapsulated by high-insulation high-temperature-resistant epoxy materials.
The voltage transformer and the current transformer adopt an alternating electromagnetic induction principle, only have a transmission path of a magnetic signal, but do not have a physical direct path, and the insulation resistance reaches more than 500 megaohms, thereby avoiding the problem of electric shock damage between a high-voltage part and a special circuit board for signal processing.
As shown in fig. 2, the signal processing unit 2 includes: the system comprises an ARM processor 10, an RAM memory 8, a digital isolation interface circuit 6, an interface circuit 7, a current differential A/D input circuit 9-1 and a voltage differential A/D input circuit 9-2; the current differential A/D input circuit 9-1 and the voltage differential A/D input circuit 9-2 are respectively and electrically connected with an ARM processor 10, and the ARM processor 10 is electrically connected with the RAM memory 8 through a bus interface; the ARM processor 10 is electrically connected to the interface circuit 7 through the digital isolation interface circuit 6.
The sensing detection unit 1 acquires current and voltage signals in the three-phase voltage A, B, C, and the sensing detection unit 1 respectively carries out differential processing on the acquired current signals and voltage signals in the three-phase voltage A, B, C and the current signals and voltage signals which are sent to the current differential A/D input circuit 9-1 and the voltage differential A/D input circuit 9-2; signals subjected to differential processing by the current differential A/D input circuit 9-1 and the voltage differential A/D input circuit 9-2 are sent to the ARM processor 10 through the analog interface circuit, and are processed by the ARM processor 10 to obtain effective values of ABC three-phase full-wave voltage and ABC three-phase full-wave current, effective values of ABC three-phase full-wave voltage, combined-phase active power, combined-phase reactive power, apparent power and combined-phase REMS power factors; the ABC three-phase full-wave current comprises power parameter information such as voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content, 1-order to 50-order voltage harmonic components and the like.
The ARM processor 10 divides the processed information into two paths, one path is stored in the RAM memory 8, and the other path is sent to the interface circuit 7 after passing through the digital isolation interface circuit 6.
The interface circuit 7 is either a 485 interface, or a CAN interface, or an SPI interface, or a UART interface, or/and a combination or a split of these.
As shown in fig. 4, the ARM processor 10 obtains ABC three-phase full-wave voltage and ABC three-phase full-wave current information, and performs digital filtering on the a-phase voltage, the a-phase current, the B-phase voltage, the B-phase current, the C-phase voltage, and the C-phase current, respectively, to obtain digital signals of the filtered a-phase voltage, the filtered a-phase current, the filtered B-phase voltage, the filtered B-phase current, the filtered C-phase voltage, and the filtered;
calculating the effective value of the phase voltage current of the A phase according to the information obtained by the phase voltage of the A phase and the phase current of the A phase;
calculating the effective value of the B-phase voltage current according to the information obtained by the B-phase voltage and the B-phase current;
calculating the effective value of the C-phase voltage current according to the information obtained by the C-phase voltage and the C-phase current;
calculating the active power and the reactive power of the phase A through the effective value of the phase voltage current of the phase A;
calculating the active power and the reactive power of the phase B through the effective value of the phase B voltage current;
calculating the active power and the reactive power of the C phase through the effective value of the C phase voltage current;
calculating the phase-combining active power, the phase-combining reactive power, the apparent power and the phase-combining REMS power factor according to the parameters; voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content and 1 to 50 times of voltage harmonic component information of ABC three-phase full-wave current;
storing said information in RAM memory 8;
the above information is sent to the interface circuit 7 upon command.
Example 2
As shown in fig. 1 and 3, a low-voltage primary power system parameter acquiring system at least includes: a sensing detection unit 1 and a signal processing unit 2;
the sensing detection unit 1 is used for acquiring current signals of three-phase voltage through a current transformer and acquiring voltage signals of the three-phase voltage through a voltage transformer;
the current processing interface is used for filtering the acquired current signals of the three-phase voltage and transmitting the filtered current signals to the signal processing unit 2;
the voltage processing interface is used for carrying out high-voltage isolation on the acquired current signals of the three-phase voltage and transmitting the current signals to the signal processing unit 2;
the signal processing unit 2 is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain effective values of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current, effective values of the ABC three-phase full-wave voltage, phase-closing active power, phase-closing reactive power, apparent power and phase-closing REMS power factors;
the signal processing unit 2 is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain the voltage frequency, the active positive power, the active negative power, the reactive positive power, the reactive negative power, the total harmonic content of the current, the total harmonic content of the voltage, the 1 st to 50 th order voltage harmonic component and other power parameters of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current.
The sensing unit 1 includes: a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3; : the first primary current feedthrough transformer 1.1, the second primary current feedthrough transformer 1.2 and the third primary current feedthrough transformer 1.3 are primary current feedthrough transformers which are respectively sleeved on an A \ B \ C three-phase power circuit loop to acquire current information of the three-phase loop and simultaneously realize electrical isolation from current sensing to current signal processing. The first primary current feedthrough transformer 1.1, the second primary current feedthrough transformer 1.2 and the third primary current feedthrough transformer 1.3 are respectively and electrically connected with a three-phase power supply current sampling filter circuit 3;
in the figure 1, the transformation ratio of a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 is 10000:1, and the transformers are used for converting a large current of more than 0-100A into a mA-level small current for output.
The three-phase voltage primary extraction circuit 4 in fig. 1 is used for directly converting primary voltage in ABC three-phase voltage into mA-level current through a voltage transformer, obtaining mV-level voltage output through high-voltage isolation conversion, and connecting the mV-level voltage output to a subsequent processing circuit.
The three-phase power supply current sampling filter circuit 3 in fig. 1 is used for converting a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 into voltage signals through a current sampling and current filtering I/V circuit, and connecting the voltage signals to a subsequent processing circuit.
The voltage transformer and the current transformer are wound by high-strength high-transformation-ratio coils and are encapsulated by high-insulation high-temperature-resistant epoxy materials.
The voltage transformer and the current transformer adopt an alternating electromagnetic induction principle, only have a transmission path of a magnetic signal, but do not have a physical direct path, and the insulation resistance reaches more than 500 megaohms, thereby avoiding the problem of electric shock damage between a high-voltage part and a special circuit board for signal processing.
As shown in fig. 3, the sensing unit 1 acquires current and voltage signals in the three-phase voltage A, B, C, and the sensing unit 1 respectively sends the acquired current and voltage signals in the three-phase voltage A, B, C to the integrated processing circuit 5 for processing; the signal processed by the integrated processing circuit 5 is sent to an ARM processor 10 through an analog interface circuit, and is processed by the ARM processor 10 to obtain ABC three-phase full-wave voltage, an effective value of ABC three-phase full-wave current, an effective value of ABC three-phase full-wave voltage, phase-closing active power, phase-closing reactive power, apparent power and phase-closing REMS power factors; the ABC three-phase full-wave current comprises power parameter information such as voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content, 1-order to 50-order voltage harmonic components and the like.
The ARM processor 10 divides the processed information into two paths, one path is stored in the RAM memory 8, and the other path is sent to the interface circuit 7 after passing through the digital isolation interface circuit 6.
The interface circuit 7 is either a 485 interface, or a CAN interface, or an SPI interface, or a UART interface, or/and a combination or a split of these.
As shown in fig. 4, the signal processing unit 2 includes: ARM processor 10, RAM memory 8, digital isolation interface circuit 6, interface circuit 7, integrated processing circuit 5; the input end of the integrated processing circuit 5 is electrically connected with a first primary current feedthrough transformer 1.1, a second primary current feedthrough transformer 1.2 and a third primary current feedthrough transformer 1.3 respectively, the output end of the integrated processing circuit 5 is electrically connected with an ARM processor 10, and the ARM processor 10 is electrically connected with an RAM memory 8 through a bus interface; the ARM processor 10 is electrically connected to the interface circuit 7 through the digital isolation interface circuit 6.
The ARM processor 10 acquires ABC three-phase full-wave voltage and ABC three-phase full-wave current information, and firstly, digital filtering is carried out on phase-A voltage, phase-A current, phase-B voltage, phase-B current, phase-C voltage and phase-C current respectively to obtain filtered digital signals of the phase-A voltage, the phase-A current, the phase-B voltage, the phase-B current, the phase-C voltage and the phase-C current;
calculating the effective value of the phase voltage current of the A phase according to the information obtained by the phase voltage of the A phase and the phase current of the A phase;
calculating the effective value of the B-phase voltage current according to the information obtained by the B-phase voltage and the B-phase current;
calculating the effective value of the C-phase voltage current according to the information obtained by the C-phase voltage and the C-phase current;
calculating the active power and the reactive power of the phase A through the effective value of the phase voltage current of the phase A;
calculating the active power and the reactive power of the phase B through the effective value of the phase B voltage current;
calculating the active power and the reactive power of the C phase through the effective value of the C phase voltage current;
calculating the phase-combining active power, the phase-combining reactive power, the apparent power and the phase-combining REMS power factor according to the parameters; voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content and 1 to 50 times of voltage harmonic component information of ABC three-phase full-wave current;
storing said information in RAM memory 8;
the above information is sent to the interface circuit 7 upon command.
In fig. 3, the integrated processing circuit 5, such as ADE7758 series, ATT7022 series, RN7302 series, etc.), is processed by the synchronous acquisition filtering and the like inside the integrated processing circuit 5, and then the ARM processor 10 exchanges data with the metering chip through the SPI interface. The ARM processor 10 obtains harmonic components of the voltage and current for more than 50 times by performing real-time FFT operation on the 6-path signals (3-path voltage and 3-path current).
The digital isolation interface circuit 6 in fig. 2 and fig. 3 is sent to the interface circuit 7, so that a universal 485, CAN, SPI and UART digital interface is realized, and the measurement result is remotely transmitted in real time according to different requirements.
In the invention, the power parameters such as ABC three-phase full-wave voltage effective value, ABC three-phase full-wave current effective value, ABC three-phase line voltage effective value, phase-combination active power, phase-combination reactive power, apparent power, phase-combination REMS power factor, voltage frequency, active positive power, active reverse power, reactive positive power, reactive reverse power, current total harmonic content, voltage total harmonic content, 1 st to 50 th order voltage harmonic component and the like which are commonly used in a low-voltage power system can be obtained through the processing of the ARM processor 10.
In the parameter measurement of the low-voltage power system, the required power parameters are changed into universal digital signals through the special mutual inductor and the special circuit board by one-time fusion (conversion), and the scheme not only solves the interconnection problem of a plurality of devices and ensures the system to have higher reliability, but also further solves the problems of complex data processing and transmission distance of the power system. A more concise and practical method is brought to the wiring of a large number of low-voltage cabinets at present. There are the following advantages.
1. The low-voltage primary transformation is adopted, a current voltage transformer of the original low-voltage cabinet is omitted, the space in the cabinet is saved, and the material cost is reduced;
2. by adopting a digital bus (485, CAN) interface, all low-voltage power parameters CAN be transmitted to a centralized display unit and a communication management unit of the low-voltage cabinet;
3. the number of the leads and the wire diameter of the leads are reduced, and the manual installation cost is reduced;
4. the calibration precision of the instrument is improved;
5. the maintenance is convenient.
The key points of the technology of the invention are as follows:
1. the invention completes the current and voltage sampling and acquisition processing device by one-time conversion;
2. when in actual use, the two parts can be simply connected into a whole through the connector assembly according to the requirement, and can be detachably installed for convenient maintenance;
3. the current-voltage conversion part can be different according to different requirements and different sizes and apertures of the die (the acquisition part is universal), so that the digital interfaces are unified;
4. the performance and parameters of the acquired data can select proper CPUs and metering chips according to different requirements;
5. when the primary instrument is calibrated in a factory, the primary through current can be applied to finish precision calibration.
The intelligent instrument has the effects that a primary power conversion technology is adopted, the problems of cost, wiring, long-distance transmission and reliability of secondary conversion of a traditional power system are solved, and the advantage of sharing multi-path data through a digital interface can be realized at present for digitalization of the intelligent instrument. At present, the similar products are not seen in the same industry at home and abroad.
Claims (9)
1. A low-voltage primary power system parameter acquisition system is characterized in that: at least comprises the following steps: a sensing detection unit (1) and a signal processing unit (2); the sensing detection unit (1) is electrically connected with the signal processing unit (2);
the sensing detection unit (1) is used for acquiring current signals of three-phase voltage through a current transformer and acquiring voltage signals of the three-phase voltage through a voltage transformer;
the current processing interface is used for filtering the acquired current signals of the three-phase voltage and transmitting the filtered current signals to the signal processing unit (2);
the voltage processing interface is used for carrying out high-voltage isolation on the acquired current signals of the three-phase voltage and transmitting the current signals to the signal processing unit (2);
the signal processing unit (2) is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain effective values of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current, effective values of the ABC three-phase full-wave voltage, combined-phase active power, combined-phase reactive power, apparent power and combined-phase REMS power factors;
the signal processing unit (2) is used for processing the obtained ABC three-phase full-wave voltage and ABC three-phase full-wave current to obtain the power parameters such as the voltage frequency, the active positive power, the active negative power, the reactive positive power, the reactive negative power, the total current harmonic content, the total voltage harmonic content, the 1 st to 50 th voltage harmonic component and the like of the ABC three-phase full-wave voltage and the ABC three-phase full-wave current.
2. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the sensing unit (1) comprises: the first primary current feedthrough mutual inductor (1.1), the second primary current feedthrough mutual inductor (1.2) and the third primary current feedthrough mutual inductor (1.3) are primary current feedthrough mutual inductors, and are respectively sleeved on an A \ B \ C three-phase power supply circuit loop to acquire current information of the three-phase loop and simultaneously realize the electrical isolation from current sensing to current signal processing.
3. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the transformation ratio of the first primary current feedthrough transformer (1.1), the second primary current feedthrough transformer (1.2) and the third primary current feedthrough transformer (1.3) is 10000:1, and the transformers are used for converting a large current of more than 0-100A into a mA-level small current for output; the first primary current feedthrough transformer (1.1), the second primary current feedthrough transformer (1.2) and the third primary current feedthrough transformer (1.3) are respectively electrically connected with the three-phase power supply current sampling filter circuit (3); the three-phase power supply current sampling filter circuit (3) is used for converting a first primary current feedthrough transformer (1.1), a second primary current feedthrough transformer (1.2) and a third primary current feedthrough transformer (1.3) into voltage signals through a current sampling and current filtering I/V circuit and connecting the voltage signals to a subsequent processing circuit.
4. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the signal processing unit (2) acquires current and voltage signals in the three-phase voltage A, B, C, and the signal processing unit (2) respectively carries out differential processing on the acquired current signal and voltage signal in the three-phase voltage A, B, C and the current signal and voltage signal which are sent to the current differential A/D input circuit (9-1) and the voltage differential A/D input circuit (9-2); signals subjected to differential processing by the current differential A/D input circuit (9-1) and the voltage differential A/D input circuit (9-2) are sent to an ARM processor (10) through a simulation interface circuit, and are processed by the ARM processor (10) to obtain effective values of ABC three-phase full-wave voltage and ABC three-phase full-wave current, effective values of ABC three-phase full-wave voltage, combined-phase active power, combined-phase reactive power, apparent power and combined-phase REMS power factors; the power parameter information of voltage frequency, active positive power, active reverse power, reactive positive power, reactive reverse power, total current harmonic content, total voltage harmonic content, 1-50 voltage harmonic components and the like of the ABC three-phase full-wave current; the ARM processor (10) divides the processed information into two paths, one path is stored in the RAM memory (8), and the other path is transmitted to the interface circuit (7) through the digital isolation interface circuit (6); the interface circuit (7) is a 485 interface, a CAN interface, an SPI interface, a UART interface or/and a collection or split-combination of the interfaces.
5. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the signal processing unit (2) acquires current and voltage signals in the three-phase voltage A, B, C, and the signal processing unit (2) respectively sends the acquired current and voltage signals in the three-phase voltage A, B, C to the integrated processing circuit (5) for processing; the signals processed by the integrated processing circuit (5) are sent to an ARM processor (10) through a simulation interface circuit, and are processed by the ARM processor (10) to obtain the effective values of ABC three-phase full-wave voltage and ABC three-phase full-wave current, the effective values of ABC three-phase full-wave voltage, the combined active power, the combined reactive power, the apparent power and the combined REMS power factor; the ABC three-phase full-wave current comprises power parameter information such as voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content, 1-order to 50-order voltage harmonic components and the like.
6. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the signal processing unit (2) comprises: the device comprises an ARM processor (10), an RAM memory (8), a digital isolation interface circuit (6), an interface circuit (7), a current differential A/D input circuit (9-1) and a voltage differential A/D input circuit (9-2); the current differential A/D input circuit (9-1) and the voltage differential A/D input circuit (9-2) are respectively and electrically connected with the ARM processor (10), and the ARM processor (10) is electrically connected with the RAM memory (8) through a bus interface; the ARM processor (10) is electrically connected with the interface circuit (7) through the digital isolation interface circuit (6).
7. A low voltage primary power system parameter acquisition system according to claim 1, wherein: the signal processing unit (2) comprises: the system comprises an ARM processor (10), an RAM memory (8), a digital isolation interface circuit (6), an interface circuit (7) and an integrated processing circuit (5); the input end of the integrated processing circuit (5) is electrically connected with a first primary current feedthrough transformer (1.1), a second primary current feedthrough transformer (1.2) and a third primary current feedthrough transformer (1.3) respectively, the output end of the integrated processing circuit (5) is electrically connected with an ARM processor (10), and the ARM processor (10) is electrically connected with an RAM memory (8) through a bus interface; the ARM processor (10) is electrically connected with the interface circuit (7) through the digital isolation interface circuit (6).
8. A low voltage primary power system parameter acquisition system according to claims 4 and 5, wherein: the ARM processor (10) acquires ABC three-phase full-wave voltage and ABC three-phase full-wave current information, and firstly performs digital filtering on the phase voltage A, the phase current A, the phase voltage B, the phase current B, the phase voltage C and the phase current C respectively to obtain digital signals of the phase voltage A, the phase current A, the phase voltage B, the phase current B and the phase current C after filtering;
calculating the effective value of the phase voltage current of the A phase according to the information obtained by the phase voltage of the A phase and the phase current of the A phase;
calculating the effective value of the B-phase voltage current according to the information obtained by the B-phase voltage and the B-phase current;
calculating the effective value of the C-phase voltage current according to the information obtained by the C-phase voltage and the C-phase current;
calculating the active power and the reactive power of the phase A through the effective value of the phase voltage current of the phase A;
calculating the active power and the reactive power of the phase B through the effective value of the phase B voltage current;
calculating the active power and the reactive power of the C phase through the effective value of the C phase voltage current;
calculating the phase-combining active power, the phase-combining reactive power, the apparent power and the phase-combining REMS power factor according to the parameters; voltage frequency, active positive power, active negative power, reactive positive power, reactive negative power, total current harmonic content, total voltage harmonic content and 1 to 50 times of voltage harmonic component information of ABC three-phase full-wave current;
storing said information in a RAM memory (8);
-sending said information to the interface circuit (7) upon command.
9. A low voltage primary power system parameter acquisition system according to claims 4 and 5, wherein: the integrated processing circuit (5) is an ADE7758 series, an ATT7022 series and an RN7302 series, and after the processing of synchronous acquisition filtering and the like in the integrated processing circuit (5), the ARM processor (10) exchanges data with the metering chip through the SPI interface; the ARM processor (10) performs real-time FFT operation on the 3 paths of voltage and the 3 paths of current to obtain harmonic components of the voltage and the current for more than 50 times.
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| TWI825753B (en) * | 2022-05-30 | 2023-12-11 | 大葉大學 | Wireless AC power monitoring module and method |
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