Voltage and current phase sequence identification device based on single-phase voltage sampling and others

Abstract

The invention belongs to the technical field of power grids, and relates to a voltage and current phase sequence recognition device based on single-phase voltage sampling and others, the phase sequence recognition device comprises a device power supply unit, a voltage sampling unit, three current detection units and a data processing unit, the device power supply unit is connected in parallel with the voltage sampling unit, and the three current detection units are connected in parallel with the data processing unit. The voltage sampling unit carries out voltage sampling on any phase line in the three-phase four-wire system power grid, the three current detection units carry out current sampling on each phase line of the three-phase four-wire system power grid, and the data processing unit reconstructs voltage signals of the other two phases according to voltage sampling models and current sampling signals. And identifying the phase sequence of the voltage and the current of the three-phase four-wire system power grid. According to the invention, the phase sequence identification of the three-phase line voltage and the three-phase current can be carried out only by sampling the single-phase voltage signal and the three-phase current signal, and the method has the characteristics of fast phase sequence identification speed and high efficiency, and also has the characteristics of simple installation, convenient use and plug-and-play.

Description

Technical Field

[0001] This invention belongs to the field of power grid technology, and specifically relates to a voltage and current phase sequence identification device based on single-phase voltage sampling and others. Background Technology

[0002] In a three-phase four-wire power grid, it is usually necessary to collect three-phase voltage and three-phase current. This usually requires professionals to manually identify and determine the phase sequence relationship of each phase voltage and current, and to manually connect the wires. This process is prone to errors and requires modification of the original power lines, making it unsuitable for ordinary users.

[0003] The same problems exist in split-phase power grids. The split-phase power grid referred to in this invention is a power supply network containing two phase lines, one neutral line, and a 120° phase difference between the two phase voltages. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a voltage and current phase sequence identification device based on single-phase voltage sampling and others. It can identify the voltage and current phase sequence relationship by only collecting single-phase voltage and phase current. It supports power drawing from the end of the power grid without modifying the original circuit. It has the characteristics of simple installation, convenient use, and plug-and-play. Moreover, it does not require professional personnel to operate. Users can install it themselves and realize the measurement of current and power.

[0005] This invention is implemented as follows: a voltage and current phase sequence identification device based on single-phase voltage sampling is provided, comprising: a device power supply unit, which draws power from any one phase line in a three-phase four-wire power grid, and whose output terminal is conductively connected to a data processing unit to supply power to the device; and a voltage sampling unit, which is connected in parallel to the input terminal of the device power supply unit, detects the single-phase voltage, and outputs a single-phase voltage signal. The data is then sent to the data processing unit; three current detection units detect the current in each phase of the three-phase four-wire power grid to obtain the three-phase current signal. , and The signal is then sent to the data processing unit; the data processing unit processes the single-phase voltage signal detected by the voltage sampling unit. Reconstruct the voltage signals of the other two phases and And combined with the three-phase current signal detected by the current detection unit , and Multiple candidate matching schemes reflecting the connection relationship between three-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in a three-phase four-wire power grid is determined based on the maximum value of the matching degree index.

[0006] Furthermore, the data processing unit includes a voltage reconstruction module and a phase-to-phase matching module, wherein the voltage reconstruction module determines the phase-to-phase matching function based on the input single-phase voltage signal. By taking into account the inherent symmetrical characteristics of a three-phase four-wire AC power supply system, the voltages of the remaining two phases are reconstructed to estimate and reconstruct the voltage signals of the other two phases. and The three-phase voltage signal obtained after reconstruction processing , and Send it to the same-phase correlation matching module.

[0007] The same-phase relationship matching module includes: a permutation and combination unit, a six-part three-matching degree calculator, and a matching relationship selector.

[0008] The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines three current signals... , , With three voltage signals , , By performing permutations and combinations, six possible voltage-current mapping schemes are generated, which are defined as follows: , , , , , and will arrive The data is fed into six three-matching calculators respectively.

[0009] The six three-match degree calculators each employ a voltage-current mapping scheme. Using the input as input, calculate the three-match accuracy index respectively. And send it to the matching relationship selector;

[0010] The matching relationship selector uses six three-matching degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the three-phase four-wire power grid to be identified.

[0011] Furthermore, the three-matching degree calculator includes: three single-matching degree calculators and a summer, wherein the three single-matching degree calculators each take the phase sequence relationship of one phase in the voltage-current mapping scheme as input and use the single-matching degree function. The single-matching degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-matching degree measure values ​​output by the three single-matching degree calculators to calculate the three-matching degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

[0012] Furthermore, the single-match degree function Defined as a power factor-based matching function, and a single matching degree function. The calculation formula is:

[0013] , Formula 2,

[0014] Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is:

[0015] , Formula 3,

[0016] In formulas 2 and 3, , ,and

[0017] The power factor PF is: , Formula 4,

[0018] The active power P is: , Formula 5,

[0019] The apparent power S is: , Formula 6,

[0020] The effective voltage value RMS(U) is: , Formula 7,

[0021] The effective value of the current, RMS(I), is: , Formula 8.

[0022] Furthermore, the current detection unit includes a current transformer. The current transformer is in the form of a semi-open clamp, which can be clamped onto the wire without damaging it and detect changes in the magnetic field (magnetic flux) on the wire.

[0023] This invention is implemented as follows, and also provides a voltage and current phase sequence identification method based on single-phase voltage sampling, using the voltage and current phase sequence identification device based on single-phase voltage sampling as described above. The phase sequence identification method includes the following steps:

[0024] Step 1: Signal Acquisition

[0025] Voltage sampling: The voltage of any one phase of the three-phase line is sampled by the voltage sampling unit to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, defining the other two unsampled phase lines as follows: Mutually, Mutually;

[0026] Current sampling: The current of the three-phase lines is sampled by the current detection unit to obtain the current signals of the three-phase lines. , , And define the three phase lines corresponding to this current signal as follows: Mutually, Mutually, Mutually.

[0027] Step 2: Data Processing

[0028] Three-phase voltage reconstruction: Based on the symmetrical characteristics of a three-phase four-wire AC power grid, and according to the sampled single-phase voltage signal... The voltage reconstruction module is used to reconstruct the voltages of the remaining two phases, thereby achieving the reconstruction of the three-phase voltage. The specific steps are as follows:

[0029] assumed And assume The phase is taken as the reference phase, with a phase of 0°. Then, considering the inherent (approximate) symmetry characteristics of a three-phase four-wire AC power supply system, the data processing unit estimates and reconstructs... , In the formula, Voltage amplitude, The power grid frequency;

[0030] Voltage and current in-phase matching: assuming mapping relationship It is a bijective function representing the pairing of phase voltages and currents in a three-phase four-wire power grid, and a three-matching degree index is defined to characterize the matching relationship between phase voltages and currents. for:

[0031] , Formula 1,

[0032] In the formula, the function It is a one-to-one matching degree function.

[0033] Based on six combinations of phase voltage and current pairing in a three-phase four-wire power grid, calculate the three-phase matching degree index under each combination condition. , , , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

[0034] This invention is implemented as follows, and also provides a power detection method for a three-phase four-wire power grid, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above for power detection.

[0035] This invention is implemented as follows, and also provides a power detection method for a three-phase four-wire power grid. It uses the voltage-current phase sequence identification method based on single-phase voltage sampling as described above to determine the phase sequence. The power detection method includes the following steps: using the current signals of the three-phase phase lines sampled by the current detection unit... , , and the voltage signal sampled by the voltage sampling unit. Then estimate the result , As the true value , Finally, based on the phase sequence matching relationship of the identified voltage and current... Perform the calculation of the required power.

[0036] This invention is implemented in the following way, and also provides a power detector for a three-phase four-wire power grid, which uses the power detection method for a three-phase four-wire power grid as described above.

[0037] This invention is implemented in the following way, and also provides a three-phase four-wire grid-connected power supply system, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above.

[0038] This invention is implemented as follows, and also provides a voltage and current phase sequence identification device based on single-phase voltage sampling, comprising: a device power supply unit, which draws power from any one phase line in a split-phase power grid, and whose output terminal is conductively connected to a data processing unit to power the device; and a voltage sampling unit, which is connected in parallel to the input terminal of the device power supply unit, detects the single-phase voltage, and outputs a single-phase voltage signal. The data is then sent to the data processing unit; two current detection units detect the current in each phase line of the split-phase power grid, respectively, to obtain two-phase current signals. and The signal is then sent to the data processing unit; the data processing unit processes the single-phase voltage signal detected by the voltage sampling unit. Estimate the two possible signals of the other phase voltage. And combined with the two-phase current signals detected by the current detection unit and Multiple candidate matching schemes reflecting the connection relationship between two-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in the split-phase power grid is determined based on the maximum value of the matching degree index.

[0039] Furthermore, the data processing unit includes a voltage reconstruction module and an in-phase correlation matching module, wherein,

[0040] The voltage reconstruction module is based on the input single-phase voltage signal. Based on the inherent symmetry characteristics of the split-phase AC power supply system, estimate the two possible signals of the other phase voltage. The voltage signal is obtained after reconstruction. , and Send to the same-phase correlation matching module;

[0041] The in-phase correlation matching module includes: a permutation and combination unit, four split-matching degree calculators, and a matching correlation selector.

[0042] The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines two current signals... and With voltage signal , , By performing permutations and combinations, four possible voltage-current mapping schemes are generated, each characterized as defined in the following ways: , , , and will arrive The data are fed into four different crack matching degree calculators;

[0043] The four split-match degree calculators each use a voltage-current mapping scheme. Using the input as input, calculate the crack matching degree index respectively. And send it to the matching relationship selector;

[0044] The matching relationship selector, in particular, matches four split-match degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the split-phase power grid to be identified.

[0045] Furthermore, the split-matching degree calculator includes: two single-matching degree calculators and a summer, wherein the two single-matching degree calculators each take the phase sequence relationship of one phase in the voltage-current mapping scheme as input and use the single-matching degree function. The single-match degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-match degree measure values ​​output by the two single-match degree calculators to calculate the split-match degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

[0046] Furthermore, the single-match degree function Defined as a power factor-based matching function, and a single matching degree function. The calculation formula is:

[0047] , Formula 12,

[0048] Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is:

[0049] , Formula 13,

[0050] In formulas 2 and 3, , ,and

[0051] The power factor PF is: , Formula 4,

[0052] The active power P is: , Formula 5,

[0053] The apparent power S is: , Formula 6,

[0054] The effective voltage value RMS(U) is: , Formula 7,

[0055] The effective value of the current, RMS(I), is: , Formula 8.

[0056] This invention is implemented as follows, and also provides a voltage and current phase sequence identification method based on single-phase voltage sampling, using the voltage and current phase sequence identification device based on single-phase voltage sampling as described above. The phase sequence identification method includes the following steps:

[0057] Step 1: Signal Acquisition

[0058] Voltage sampling: The voltage is sampled from any one phase of the two-phase line by a voltage sampling unit to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, define the other unsampled phase line as Mutually;

[0059] Current sampling: The current is sampled from the two phase lines by the current detection unit to obtain the current signal of the two phase lines. and And define the two phase lines corresponding to the current signal as follows: Harmony Mutually;

[0060] Step 2: Data Processing

[0061] Three-phase voltage reconstruction: Based on the symmetrical characteristics of split-phase AC power grids, and using the sampled single-phase voltage signals... Estimate the two possible signals of the other phase voltage. The specific steps are as follows:

[0062] assumed And assume The phase of the first phase is the reference phase, with a phase of 0°. The voltage waveform of the other phase has two possibilities: phase lag. Phase 120° and ahead With a phase angle of 120°, set the voltages of these two phases as follows: and Based on the above system conditions, the data processing unit can estimate the two possible voltage signals for this phase as follows:

[0063] , In the formula, U m Where f is the voltage amplitude and f is the grid frequency;

[0064] Voltage and current in-phase matching: Assume the mapping relationship σ:{x,y}→{a,b}or{a,c} is an injective function representing the pairing of current and voltage in each phase of a split-phase system. And define the split-phase matching degree index F(σ) to characterize the in-phase matching relationship of voltage and current in each phase as:

[0065] , Formula 11,

[0066] In the formula, the function It is a single-match degree function;

[0067] Based on the four combinations of phase voltage and current pairing in a split-phase power grid, the split-phase matching degree index is calculated for each combination condition. , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

[0068] This invention is implemented as follows, and also provides a power detection method for split-phase power grids, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above for power detection.

[0069] This invention is implemented as follows, and also provides a power detection method for a split-phase power grid, which uses the voltage and current phase sequence identification method based on single-phase voltage sampling as described above for phase sequence determination. The power detection method includes the following steps:

[0070] The current signals of the two phase lines are sampled using the current detection unit. and and the voltage signal sampled by the voltage sampling unit. Estimate the two possible signals of the other phase voltage. Finally, based on the phase sequence matching relationship of the identified voltage and current... Perform the calculation of the required power.

[0071] This invention is implemented in the following way, and also provides a power detector for a split-phase power grid, which uses the power detection method for a split-phase power grid as described above.

[0072] This invention is implemented in the following way, and also provides a split-phase grid-connected power supply system, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above.

[0073] Compared with existing technologies, the present invention provides a voltage and current phase sequence identification device based on single-phase voltage sampling. The single-phase voltage sampling-based voltage and current phase sequence identification device includes: a power supply unit, a voltage sampling unit, three current detection units, and a data processing unit. The power supply unit and the voltage sampling unit are connected in parallel. The voltage sampling unit samples the voltage of any one phase line in a three-phase four-wire power grid. The three current detection units sample the current of each phase line in the three-phase four-wire power grid. The data processing unit reconstructs the voltage signals of the other two phases based on the voltage sampling signals and, combined with the current sampling signals, generates multiple candidate matching schemes reflecting the connection relationship between the three-phase current and voltage. It calculates the matching degree index of each candidate matching scheme and determines the actual phase sequence relationship between voltage and current in the three-phase four-wire power grid based on the maximum value of the matching degree index. This invention only requires sampling a single-phase voltage signal and three-phase current signals to perform phase sequence identification of the three-phase line voltage and current. It features fast phase sequence identification speed and high efficiency, as well as simple installation, convenient use, and plug-and-play functionality. Furthermore, it requires no professional personnel to operate; users can install it themselves and achieve current and power measurement. After completing the phase sequence identification of the three-phase line voltage and current, this invention eliminates the need for rewiring according to the correct phase sequence. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the voltage and current phase sequence identification device based on single-phase voltage sampling applicable to three-phase four-wire power grids according to the present invention.

[0075] Figure 2 and Figure 3 for Figure 1 A schematic diagram illustrating the principle of the same-phase correlation matching module;

[0076] Figure 4 This is a schematic diagram of the voltage and current phase sequence identification device based on single-phase voltage sampling applicable to split-phase power grids according to the present invention;

[0077] Figure 5 , Figure 6 for Figure 4 A schematic diagram of the principle of the same-phase correlation matching module.

[0078] The labels in the diagram are as follows: 1. Power supply unit; 2. Voltage sampling unit; 3. Current detection unit; 4. Data processing unit; 5. In-phase matching module; 6. Voltage reconstruction module; 7. Arrangement and combination device; 8. Three-match degree calculator; 9. Matching relationship selector; 10. Single-match degree calculator; 11. Summator. Detailed Implementation

[0079] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0080] Example 1

[0081] Please refer to Figure 1 As shown, a preferred embodiment of the voltage and current phase sequence identification device based on single-phase voltage sampling of the present invention includes: a device power supply unit 1, a voltage sampling unit 2, three current detection units 3, and a data processing unit 4.

[0082] The device power supply unit 1 draws power from any one phase of a three-phase four-wire power grid, and its output terminal is electrically connected to the data processing unit 4 to supply power to the device.

[0083] Voltage sampling unit 2 is connected in parallel to the input terminal of power supply unit 1 to detect the single-phase voltage and output a single-phase voltage signal. And send it to data processing unit 4.

[0084] Three current detection units 3 detect the current in each phase of a three-phase four-wire power grid, respectively, to obtain three-phase current signals. , and And send it to data processing unit 4.

[0085] Data processing unit 4 processes the single-phase voltage signal detected by voltage sampling unit 2. Reconstruct the voltage signals of the other two phases and And combined with the three-phase current signal detected by the current detection unit , and Multiple candidate matching schemes reflecting the connection relationship between three-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in a three-phase four-wire power grid is determined based on the maximum value of the matching degree index.

[0086] Specifically, the data processing unit 4 includes a voltage reconstruction module 6 and an in-phase correlation matching module 5.

[0087] The voltage reconstruction module is based on the input single-phase voltage signal. By taking into account the inherent (approximate) symmetrical characteristics of a three-phase four-wire AC power supply system, the voltages of the remaining two phases are reconstructed to estimate and reconstruct the voltage signals of the other two phases. and The three-phase voltage signal obtained after reconstruction processing , and The data is then sent to the phase correlation matching module. The symmetry characteristic refers to the three-phase phase lines... , , With zero line The three-phase voltages between them have the same frequency. Equivalent amplitude And the relationship between them, which are fixed at a phase angle of 120°.

[0088] The same-phase relationship matching module includes: a permutation and combination unit, a six-part three-matching degree calculator, and a matching relationship selector.

[0089] The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines three current signals... , , With three voltage signals , , By performing permutations and combinations, six possible voltage-current mapping schemes are generated, each characterized as defined in the following ways: , , , , , and will arrive The data is fed into six three-matching calculators respectively.

[0090] The six three-match degree calculators each employ a voltage-current mapping scheme. Using the input as input, calculate the three-match accuracy index respectively. And send it to the matching relationship selector.

[0091] The matching relationship selector uses six three-matching degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the three-phase four-wire power grid to be identified.

[0092] Specifically, the three-matching degree calculator includes: three single-matching degree calculators and a summer, wherein the three single-matching degree calculators each take the phase sequence relationship of one phase in the voltage-current mapping scheme as input and use the single-matching degree function. The single-matching degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-matching degree measure values ​​output by the three single-matching degree calculators to calculate the three-matching degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

[0093] Specifically, the single-match degree function Defined as a matching function based on the power factor. The single-matching degree function. The calculation formula is:

[0094] , Formula 2,

[0095] Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is:

[0096] , Formula 3.

[0097] In formulas 2 and 3, , ,and

[0098] The power factor PF is: , Formula 4,

[0099] The active power P is: , Formula 5,

[0100] The apparent power S is: , Formula 6,

[0101] The effective voltage value RMS(U) is: , Formula 7,

[0102] The effective value of the current, RMS(I), is: , Formula 8.

[0103] This invention utilizes the fundamental characteristics of a three-phase four-wire AC power supply system to design a matching degree metric function related to the power factor. Based on the calculated value of the matching degree metric function, the phase sequence of voltage and current in the three-phase four-wire power grid is obtained. The fundamental characteristics include the following two points: (A) Small phase difference between voltage and current on the same phase (high power factor). (B) When the current in a certain phase is small, the power factor of that phase may be low.

[0104] Specifically, the current detection unit 3 includes a current transformer. The current transformer is in the form of a semi-open clamp, which can be clamped onto the wire without damaging it and detect changes in the magnetic field (magnetic flux) on the wire.

[0105] Example 2

[0106] Please refer to Figure 1 As shown, this is a preferred embodiment of the voltage and current phase sequence identification device based on single-phase voltage sampling of the present invention. The background is that the power grid has a slight three-phase voltage imbalance. The effective voltage of the phase is 230V. The effective voltage of the phase is 227V. The effective voltage of the phase is 232V. Phase voltage lag Phase voltage 119.14°, Phase voltage lag Phase voltage 121.42°. The effective value of the phase current is 2.192A. The effective value of the phase current is 1.626A. The effective value of the phase current is 1.980A. Relevant power parameters include: The active power of the phase is 479.43W, the apparent power is 504.11VA, and the power factor is 0.9510. The active power of the phase is 316.92W, the apparent power is 365.18VA, and the power factor is 0.8584. The active power of the phase is 435.94W, the apparent power is 459.38VA, and the power factor is 0.9490. Active current component: The active current component of the phase is 2.084A. The active current component of the phase is 1.396A. The active current component of the phase is 1.879A.

[0107] The voltage and current phase sequence identification device based on single-phase voltage sampling of the present invention includes: a device power supply unit 1, a voltage sampling unit 2, three current detection units 3 and a data processing unit 4.

[0108] The device power supply unit 1 draws power from any one phase of the three-phase four-wire power grid. In this embodiment, it actually draws power from phase L1. Its output terminal is electrically connected to the data processing unit 4 to supply power to the device.

[0109] Voltage sampling unit 2 is connected in parallel to the input terminal of power supply unit 1 to detect the single-phase voltage and output a single-phase voltage signal. And send it to data processing unit 4.

[0110] Three current detection units 3 detect the current of each phase wire in a three-phase four-wire power grid, respectively. In this embodiment, the three current detection units draw power from phases L1, L2, and L3, and obtain three-phase current signals respectively. , and And send it to data processing unit 4.

[0111] The data processing unit 4 includes a voltage reconstruction module 6 and an in-phase correlation matching module 5.

[0112] The voltage reconstruction module 6, based on the input single-phase voltage signal... The calculated amplitude is 325.22V, and the frequency is 50Hz. Based on the inherent symmetrical characteristics of a three-phase four-wire AC power supply system, the voltage signals of the other two phases are estimated. and The reconstructed three-phase voltage signal , and Send it to the same-phase correlation matching module.

[0113] The same-phase relationship matching module 5 includes: a permutation and combination unit 7, a six-three-match degree calculator 8, and a matching relationship selector 9.

[0114] The arrangement and combination unit 7, based on a real but unknown voltage-current phase sequence matching relationship, combines the three current signals... , , With three voltage signals , , By performing permutations and combinations, six possible voltage-current mapping schemes are generated, which are defined as follows: , , , , , and will arrive The data is fed into six three-matching calculators.

[0115] Each of the six three-way matching degree calculators 8 comprises three single-way matching degree calculators 10 and a summer 11. The three single-way matching degree calculators 10 each take a phase sequence relationship from the voltage-current mapping scheme as input and use a single-way matching degree function. The system calculates the single-matching degree metric values ​​of the input current and voltage. The summer 11 sums the single-matching degree metric values ​​output from the three single-matching degree calculators to calculate the three-matching degree index. .

[0116] In this embodiment, the three-match accuracy index is calculated using Formula 1 and Formula 2: , , , , , .

[0117] The three-match accuracy index is calculated using formulas 1 and 3: , , , , , .

[0118] Among them, the matching relationship selector 9 has six three-matching degree metrics. to In the middle, select the maximum value. In this embodiment, Maximum. The mapping scheme corresponding to this value. The voltage-current matching relationship is characterized ,Right now and same phase, and same phase, and By identifying the phase sequence, the actual phase sequence relationship between voltage and current in a three-phase four-wire power grid can be determined.

[0119] Example 3

[0120] Please refer to again Figure 1 As shown, this invention also discloses a voltage and current phase sequence identification method based on single-phase voltage sampling, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above. The phase sequence identification method includes the following steps:

[0121] Step 1: Signal Acquisition

[0122] Voltage sampling: Voltage sampling unit 2 samples the voltage of any one phase of the three-phase line to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, defining the other two unsampled phase lines as follows: Mutually, Mutually.

[0123] Current sampling: The current of the three-phase wires (live wires) is sampled by the current detection unit 3 to obtain the current signals of the three-phase wires. , , , and respectively define the three-phase phase lines corresponding to the current signal as phase, phase, phase.

[0124] Since there are actually only three-phase power in a three-phase four-wire power supply system, therefore, " phase, phase, phase" and " phase, phase, phase" have a one-to-one correspondence relationship (i.e., a physical correspondence relationship) that is temporarily unknown but necessarily exists.

[0125] Step 2: Data processing

[0126] Three-phase voltage reconstruction: Based on the (approximate) symmetry characteristics of a three-phase four-wire AC power grid, according to the single-phase voltage signal obtained by sampling , use the voltage reconstruction module to reconstruct the other two-phase voltages, and the specific steps are as follows:

[0127] Assume , and assume The phase of is the reference phase, and the phase is 0°. Then, combined with the inherent (approximate) symmetry characteristics of the three-phase four-wire AC power supply system, the data processing unit 4 estimates and reconstructs , , where is the voltage amplitude, is the power grid frequency.

[0128] The three-phase voltage reconstruction depends on the symmetry of the three-phase four-wire power grid. There are slight imbalances and harmonic disturbances in the actual power grid, but the method of this invention for phase sequence identification and power calculation based on the power grid symmetry as the basic voltage signal is still effective in the actual power grid.

[0129] Because the three-phase four-wire power grid is a symmetric (or approximately symmetric) AC system, its core characteristics are that the three-phase voltages ( phase, phase, relative to the neutral line ) have the same frequency ([[ID=6o]] ), basically equal voltage amplitudes ( [[ID=°63]]) and a phase relationship with a fixed phase difference of 120° electrical angle between each other.

[0130] Voltage-current in-phase relationship matching: Assume that the mapping relationship is a bijective function for pairing the voltages and currents of each phase in a three-phase four-wire power grid, and define the three-phase matching degree index for:

[0131] , Formula 1,

[0132] In the formula, the function It is a one-to-one matching degree function.

[0133] Based on six combinations of phase voltage and current pairing in a three-phase four-wire power grid, calculate the three-phase matching degree index under each combination condition. , , , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

[0134] The matching principle of the three-phase four-wire voltage and current in this invention is as follows:

[0135] Under normal conditions in a three-phase four-wire power supply system, the phase difference between the voltage and current of a load connected to the same phase is ( The voltage across the same phase depends primarily on the impedance characteristics of the load itself (e.g., inductive, capacitive, resistive). For most electrical loads, the voltage across the same phase... and current phase difference between absolute value Relatively small, close to 0° (i.e., power factor) Higher, usually Even close to 1). Conversely, if voltages and currents of different phases are "forcedly paired" and the "power factor" is calculated, the calculated "power factor" PF will be very low due to the phase difference of about 120° or 240° between them. The value is very small, for example: , This is significantly inconsistent with actual load characteristics. That is, the phase difference between voltage and current on the same phase is primarily determined by the load; under normal load... Smaller → Power factor ( The value approaches 1; PF decreases significantly during phase reversal.

[0136] In a three-phase four-wire power supply system, the three phase wires ( Mutually, Mutually, (phase) and the detected three current signals , , There is a strict physical correspondence between them, and the reconstructed three-phase voltages ( , , The three phase lines () represent the voltages of these three phase lines, therefore there must exist a unique and correct mapping combination to represent the current signal. , , Distributed to the corresponding voltage phase ( Mutually, Mutually, (phase) so that the voltage and current on each phase belong to the same physical circuit.

[0137] A true match is one of 3! = 6 possible combinations, such as: or wait.

[0138] Six possible voltage and current pairings are listed below:

[0139] ;

[0140] ;

[0141] ;

[0142] ;

[0143] ;

[0144] .

[0145] The voltage and current phase sequence identification method based on single-phase voltage sampling of this invention is effective when the power factor of each phase is >0.5, and has the best identification accuracy when the power factor of each phase is >0.7. Since three-phase power grids have regulations stipulating that the voltage imbalance is ≤2% and the power factor is >0.7, the voltage and current phase sequence identification method based on single-phase voltage sampling of this invention has universal applicability.

[0146] Example 4

[0147] The present invention also discloses a power detection method for a three-phase four-wire power grid, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above for power detection.

[0148] Example 5

[0149] This invention also discloses a power detection method for a three-phase four-wire power grid, which uses the voltage and current phase sequence identification method based on single-phase voltage sampling as described above to determine the phase sequence. The power detection method includes the following steps: using the current signals of the three-phase phase lines sampled by the current detection unit 3. , , and the voltage signal sampled by voltage sampling unit 2 Then estimate the result , As the true value , Finally, based on the phase sequence matching relationship of the identified voltage and current... Perform the calculation of the required power.

[0150] The power detection method for a three-phase four-wire power grid of the present invention will be further illustrated below through specific embodiments.

[0151] Example 6

[0152] Please refer to again Figure 1 As shown, this is an embodiment of the power detection method for a three-phase four-wire power grid of the present invention.

[0153] First, for a three-phase four-wire power supply system, the actual power supply parameters of the system are as follows:

[0154] The voltage sampling unit 2 of the voltage and current phase sequence identification device based on single-phase voltage sampling is connected to... On the phase, the three current detection units 3 are respectively clamped to Phase line, Phase line, On the phase lines. The power grid has a slight three-phase voltage imbalance. The effective voltage of the phase is 230V. The effective voltage of the phase is 227V. The effective voltage of the phase is 232V. Phase voltage lag Phase voltage 119.14°, Phase voltage lag Phase voltage 121.42°. The effective value of the phase current is 2.192A. The effective value of the phase current is 1.626A. The effective value of the phase current is 1.980A.

[0155] The relevant power parameters are: The active power of the phase is 479.43W, the apparent power is 504.11VA, and the power factor is 0.9510. The active power of the phase is 316.92W, the apparent power is 365.18VA, and the power factor is 0.8584. The active power of the phase is 435.94W, the apparent power is 459.38VA, and the power factor is 0.9490. Active current component: The active current component of the phase is 2.084A. The active current component of the phase is 1.396A. The active current component of the phase is 1.879A.

[0156] Secondly, the steps of the power detection method for a three-phase four-wire power grid according to the present invention are as follows:

[0157] Step 1: Detect the voltage signal of any phase in the three-phase four-wire power grid using voltage sampling unit 2. The effective voltage value is 230V, and the current signals of the three phase lines are detected by three current detection units 3. , , .

[0158] Step 2: Based on the voltage signal The calculated amplitude is 325.22V, and the frequency is 50Hz. Based on this, the following can be estimated: , Instantaneous waveform:

[0159] ,

[0160] .

[0161] The estimated values ​​will be used later. , As , Participate in the calculation.

[0162] Step 3: The six possible voltage and current mapping relationships are as follows , , , , , The six possible voltage and current pairing combinations are as follows:

[0163] ;

[0164] ;

[0165] ;

[0166] ;

[0167] ;

[0168] .

[0169] The three-match accuracy index is calculated using Formula 1 and Formula 2: , , , , , Solve this problem. , and thus .

[0170] The three-match accuracy index is calculated using formulas 1 and 3: , , , , , Solve this problem. , and thus .

[0171] In the two calculation methods mentioned above, the solution is... All are The mapping relationship is as follows: ,Right now and These are the voltage and current of the same phase. and These are the voltage and current of the same phase. and These are the voltage and current of the same phase, thus completing the phase sequence identification of voltage and current.

[0172] Step 4: Based on the detection in Step 1 , , , and the estimated in step 2 , As the true value , And the determined voltage-current in-phase relationship obtained in step 3. Power calculations are performed, using formulas 4, 5, 6, and 10 to calculate the active power, apparent power, power factor, and active current component of each phase. The results at this point are:

[0173] P a =479.43W, S a =504.11VA, PF a =0.9510, i active_a =2.084A;

[0174] P b =323.95W, S b =374.06VA, PF b =0.8660, iactive_b =1.408A;

[0175] P c =430.75W, S c =455.42VA, PF c =0.9458, i active_c =1.873A.

[0176] The active current component is calculated using Formula 10, which is:

[0177] m-phase active current component In the formula, m∈{a,b,c}.

[0178] Example 7

[0179] This invention also discloses a power detector for a three-phase four-wire power grid, which uses the power detection method for a three-phase four-wire power grid as described above. The data processing unit 4 also includes a power calculation unit (not shown in the figure), which calculates the required power.

[0180] Example 8

[0181] The present invention also discloses a three-phase four-wire grid-connected power supply system, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above.

[0182] Example 9

[0183] This invention also discloses a voltage and current phase sequence identification device based on single-phase voltage sampling applicable to split-phase power supply systems, comprising:

[0184] The device power supply unit draws power from any one phase line in the split-phase power grid, and its output terminal is electrically connected to the data processing unit to supply power to the device.

[0185] The voltage sampling unit is connected in parallel to the input terminal of the device's power supply unit to detect the single-phase voltage and output a single-phase voltage signal. And send it to the data processing unit;

[0186] Two current detection units detect the current in each phase line of the split-phase power grid, respectively, to obtain two-phase current signals. and And send it to the data processing unit;

[0187] The data processing unit processes the single-phase voltage signal detected by the voltage sampling unit. Estimate the two possible signals of the other phase voltage. And combined with the two-phase current signals detected by the current detection unit and Multiple candidate matching schemes reflecting the connection relationship between two-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in the split-phase power grid is determined based on the maximum value of the matching degree index.

[0188] Specifically, the data processing unit includes a voltage reconstruction module and an in-phase correlation matching module, wherein,

[0189] The voltage reconstruction module is based on the input single-phase voltage signal. Based on the inherent symmetry characteristics of the split-phase AC power supply system, estimate the two possible signals of the other phase voltage. The voltage signal is obtained after reconstruction. , and Send to the same-phase correlation matching module;

[0190] The in-phase correlation matching module includes: a permutation and combination unit, four split-matching degree calculators, and a matching correlation selector.

[0191] The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines two current signals... and With voltage signal , , By performing permutations and combinations, four possible voltage-current mapping schemes are generated, each characterized as defined in the following ways: , , , and will arrive The data are fed into four different crack matching degree calculators;

[0192] The four split-match degree calculators each use a voltage-current mapping scheme. Using the input as input, calculate the crack matching degree index respectively. And send it to the matching relationship selector;

[0193] The matching relationship selector, in particular, matches four split-match degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the split-phase power grid to be identified.

[0194] Specifically, the split-matching degree calculator includes: two single-matching degree calculators and a summer, wherein the two single-matching degree calculators each take a phase sequence relationship in the voltage-current mapping scheme as input and use a single-matching degree function. The single-match degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-match degree measure values ​​output by the two single-match degree calculators to calculate the split-match degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

[0195] Specifically, the split-matching degree calculator includes: two single-matching degree calculators and a summer, wherein the two single-matching degree calculators each take a phase sequence relationship in the voltage-current mapping scheme as input and use a single-matching degree function. The single-match degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-match degree measure values ​​output by the two single-match degree calculators to calculate the split-match degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

[0196] Furthermore, the single-match degree function Defined as a power factor-based matching function, and a single matching degree function. The calculation formula is:

[0197] , Formula 12,

[0198] Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is:

[0199] , Formula 13,

[0200] In formulas 2 and 3, , ,and

[0201] The power factor PF is: , Formula 4,

[0202] The active power P is: , Formula 5,

[0203] The apparent power S is: , Formula 6,

[0204] The effective voltage value RMS(U) is: , Formula 7,

[0205] The effective value of the current, RMS(I), is: , Formula 8.

[0206] Example 10

[0207] This invention also discloses a voltage and current phase sequence identification method based on single-phase voltage sampling applicable to split-phase power supply systems, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above. The phase sequence identification method includes the following steps:

[0208] Step 1: Signal Acquisition

[0209] Voltage sampling: Voltage sampling unit 2 samples the voltage of any one phase of the two phase lines to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, defined as the unsampled phase line. Mutually.

[0210] Current sampling: The current detection unit 3 samples the current of the two phase lines to obtain the current signals of the two phase lines. and And define the phase line corresponding to the current signal as , respectively. Harmony Mutually.

[0211] Step 2: Data Processing

[0212] Three-phase voltage reconstruction: For split-phase systems with a phase difference of 120° (or 2π / 3 radians), where two phases have the same frequency and amplitude. Based on the sampled single-phase voltage signal... The estimation of the voltage of the other phase is achieved through the following steps:

[0213] assumed And assume The phase of the first phase is the reference phase, with a phase angle of 0°. The other phase voltage waveform has two possibilities: phase lag. Phase 120° and ahead Phase 120°. Let these two possibilities be set as follows: , Based on the above system conditions, data processing unit 4 can estimate the two possible voltage signals for this phase as follows:

[0214] ,

[0215] ,

[0216] In the formula, Where is the voltage amplitude, and f is the grid frequency. For lag In the case of a phase angle of 120°, To be ahead of time The case of phase 120°.

[0217] Voltage and current in-phase matching: Assume the mapping σ:{x,y}→{a,b}or{a,c} is an injective function of the phase current and voltage pairings in a split-phase system. Four possible voltage and current pairing combinations are enumerated as follows:

[0218] σ1(x)=a, σ1(y)=b;

[0219] σ²(x) = a, σ²(y) = c;

[0220] σ3(x)=b, σ3(y)=a;

[0221] σ4(x)=c, σ4(y)=a.

[0222] Define a split-term matching index to characterize the matching relationship between voltage and current in each phase. for:

[0223] , Formula 11,

[0224] In the formula, the function It is a one-to-one matching degree function.

[0225] Based on the four combinations mentioned above, calculate the crack matching degree metric index for each combination condition. , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

[0226] Example 11

[0227] The present invention also discloses a power detection method for a split-phase power grid, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above for power detection.

[0228] Example 12

[0229] This invention also discloses a power detection method for a split-phase power grid, which uses the voltage-current phase sequence identification method based on single-phase voltage sampling as described above to determine the phase sequence. The power detection method includes the following steps: using the current signals of two phase lines sampled by the current detection unit... and and the voltage signal sampled by the voltage sampling unit. Estimate the two possible signals of the other phase voltage. Finally, based on the phase sequence matching relationship of the identified voltage and current... Perform the calculation of the required power.

[0230] Example 13

[0231] The present invention also discloses a power detector for a split-phase power grid, which uses the power detection method for a split-phase power grid as described above.

[0232] Example 14

[0233] The present invention also discloses a split-phase grid-connected power supply system, which uses the voltage and current phase sequence identification device based on single-phase voltage sampling as described above.

[0234] Example 15

[0235] Please refer to the following at the same time: Figures 4-6 As shown, the first embodiment of the power detection method for the split-phase power supply system of the present invention includes the following steps:

[0236] First, for a split-phase power supply system with a 120° phase difference, the actual power supply parameters of the system are as follows:

[0237] The voltage sampling unit 2 of the voltage-current phase sequence identification device based on single-phase voltage sampling is connected to phase L1, and two current detection units 3 are clamped to phase L1 and phase L2 respectively. The effective value of the voltage of phase L1 is 230V, and the effective value of the voltage of phase L2 is 228V. The voltage of phase L2 lags the voltage of phase L1 by 120°. The effective value of the current of phase L1 is 1.909A, and the effective value of the current of phase L2 is 2.263A.

[0238] Relevant power parameters are as follows: Phase L1 has an active power of 417.57W, an apparent power of 439.06VA, and a power factor of 0.9510. Phase L2 has an active power of 495.02W, an apparent power of 515.93VA, and a power factor of 0.9595. Active current components: Phase L1 has an active current component of 1.8156A, and Phase L2 has an active current component of 2.1711A.

[0239] Secondly, the steps for power detection using the power detection method for split-phase power grid of the present invention are as follows:

[0240] Step 1: Detect the voltage signal U of any phase in the three-phase four-wire power grid using voltage sampling unit 2. a The effective voltage value of (t) is 230V, and the current signal i of the three-phase line is detected by two current detection units 3. x (t), i y (t).

[0241] Step 2: Based on the voltage signal U a (t), its amplitude is calculated to be 325.22V, and its frequency is 50Hz. The other phase voltage waveform has two possibilities: phase lag. Phase 120° and ahead Phase 120°. Let these two possibilities be set as follows: , Based on the above system conditions, data processing unit 4 can estimate the two possible voltage signals for this phase as follows:

[0242] ,

[0243] ,

[0244] Step 3: The four possible voltage and current mapping relationships are σ1, σ2, σ3, and σ4, respectively. The four possible voltage and current pairing combinations are as follows:

[0245] σ1(x)=a, σ1(y)=b;

[0246] σ²(x) = a, σ²(y) = c;

[0247] σ3(x)=b, σ3(y)=a;

[0248] σ4(x)=c, σ4(y)=a.

[0249] The matching degree index is calculated using formulas 11 and 12: =0.956、 =0.563、 =0.488、、 =0.223. Solving arg max(F(σ)), we get... = .

[0250] The matching degree index is calculated using formulas 11 and 13: =0.955、 =0.594、 =0.466、、 =0.222. Solving arg max(F(σ)), we get... = .

[0251] In the two matching degree index calculation methods mentioned above, the solution obtained is... All are The mapping relationship is: σ1(x)=a, σ1(y)=b, that is... The approximate voltage waveform of the phase is lag Phase voltage 120°, and yes Phase current, yes The phase current is used to complete the phase sequence identification of voltage and current.

[0252] Step 4: Based on the detection in Step 1 , , The power is calculated using the determined phase sequence relationship σ obtained in step 3, and the active power, apparent power, power factor, and active current component of each phase are obtained through rolling calculations using formulas 4, 5, 6, and 10. The result at this point is:

[0253] P1=417.57W, S1=439.06VA, PF1=0.9510, i active_1 =1.816A;

[0254] P2=499.37W, S2=520.45VA, PF2=0.9595, i active_2 =2.170A.

[0255] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A voltage and current phase sequence identification device based on single-phase voltage sampling, characterized in that, include: The device power supply unit draws power from any one phase of a three-phase four-wire power grid, and its output terminal is electrically connected to the data processing unit to supply power to the device. The voltage sampling unit is connected in parallel to the input terminal of the device's power supply unit to detect the single-phase voltage and output a single-phase voltage signal. And send it to the data processing unit; Three current detection units detect the current in each phase of a three-phase four-wire power grid, respectively, to obtain three-phase current signals. , and And send it to the data processing unit; The data processing unit processes the single-phase voltage signal detected by the voltage sampling unit. Reconstruct the voltage signals of the other two phases and And combined with the three-phase current signal detected by the current detection unit , and Multiple candidate matching schemes reflecting the connection relationship between three-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in a three-phase four-wire power grid is determined based on the maximum value of the matching degree index.

2. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 1, characterized in that, The data processing unit includes a voltage reconstruction module and an in-phase correlation matching module, wherein, The voltage reconstruction module is based on the input single-phase voltage signal. By taking into account the inherent symmetrical characteristics of a three-phase four-wire AC power supply system, the voltages of the remaining two phases are reconstructed to estimate and reconstruct the voltage signals of the other two phases. and The reconstructed three-phase voltage signal is then obtained. , and Send to the same-phase correlation matching module; The same-phase relationship matching module includes: a permutation and combination unit, a six-part three-matching degree calculator, and a matching relationship selector. The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines three current signals... , , With three voltage signals , , By performing permutations and combinations, six possible voltage-current mapping schemes are generated, each characterized as defined in the following ways: , , , , , and will arrive The data are fed into six three-matching calculators respectively; The six three-match degree calculators each employ a voltage-current mapping scheme. Using the input as input, calculate the three-match accuracy index respectively. And send it to the matching relationship selector; The matching relationship selector uses six three-matching degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the three-phase four-wire power grid to be identified.

3. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 2, characterized in that, The three-matching degree calculator includes: three single-matching degree calculators and a summer. The three single-matching degree calculators each take a phase sequence relationship from the voltage-current mapping scheme as input and use a single-matching degree function. The single-matching degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-matching degree measure values ​​output by the three single-matching degree calculators to calculate the three-matching degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

4. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 3, characterized in that, The single-match degree function Defined as a power factor-based matching function, and a single matching degree function. The calculation formula is: , Formula 2, Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is: , Formula 3, In formulas 2 and 3, , ,and The power factor PF is: , Formula 4, The active power P is: , Formula 5, The apparent power S is: , Formula 6, The effective voltage value RMS(U) is: , Formula 7, The effective value of the current, RMS(I), is: , Formula 8.

5. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 1, characterized in that, The current detection unit includes a current transformer.

6. A voltage and current phase sequence identification method based on single-phase voltage sampling, characterized in that, The voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 1 to 5 is used, and the phase sequence identification method includes the following steps: Step 1: Signal Acquisition Voltage sampling: The voltage of any one phase of the three-phase line is sampled by the voltage sampling unit to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, defining the other two unsampled phase lines as follows: Mutually, Mutually; Current sampling: The current of the three-phase lines is sampled by the current detection unit to obtain the current signals of the three-phase lines. , , And define the three phase lines corresponding to this current signal as follows: Mutually, Mutually, Mutually; Step 2: Data Processing Three-phase voltage reconstruction: Based on the symmetrical characteristics of a three-phase four-wire AC power grid, and according to the sampled single-phase voltage signal... The voltage reconstruction module is used to reconstruct the voltages of the remaining two phases, thereby achieving the reconstruction of the three-phase voltage. The specific steps are as follows: assumed And assume The phase is taken as the reference phase, and the phase is 0°. Then, considering the inherent symmetry characteristics of the three-phase four-wire AC power supply system, the data processing unit estimates and reconstructs... , In the formula, U m Where f is the voltage amplitude and f is the grid frequency; Voltage and current in-phase matching: assuming mapping relationship Let F(σ) be the bijective function representing the pairing of phase voltages and currents in a three-phase four-wire power grid, and define the three-phase matching degree index F(σ) to characterize the matching relationship between phase voltages and currents as follows: , Formula 1, In the formula, the function It is a single-match degree function; Based on six combinations of phase voltage and current pairing in a three-phase four-wire power grid, calculate the three-phase matching degree index under each combination condition. , , , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

7. A power detection method for a three-phase four-wire power grid, characterized in that, It uses a voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 1 to 5 for power detection.

8. A power detection method for a three-phase four-wire power grid, characterized in that, It uses the voltage and current phase sequence identification method based on single-phase voltage sampling as described in claim 6 to determine the phase sequence, and the power detection method includes the following steps: The current signals of the three phase lines are sampled using the current detection unit. , , and the voltage signal sampled by the voltage sampling unit. Then estimate the result , As the true value , Finally, based on the phase sequence matching relationship of the identified voltage and current... Calculate the required power.

9. A power detector for a three-phase four-wire power grid, characterized in that, It uses the power detection method for a three-phase four-wire power grid as described in claim 7 or 8.

10. A three-phase four-wire grid-connected power supply system, characterized in that, It uses a voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 1 to 5.

11. A voltage and current phase sequence identification device based on single-phase voltage sampling, characterized in that, include: The device power supply unit draws power from any one phase line in the split-phase power grid, and its output terminal is electrically connected to the data processing unit to supply power to the device. The voltage sampling unit is connected in parallel to the input terminal of the device's power supply unit to detect the single-phase voltage and output a single-phase voltage signal. And send it to the data processing unit; Two current detection units detect the current in each phase line of the split-phase power grid, respectively, to obtain two-phase current signals. and And send it to the data processing unit; The data processing unit processes the single-phase voltage signal detected by the voltage sampling unit. Estimate the two possible signals for the other phase voltage. And combined with the two-phase current signals detected by the current detection unit and Multiple candidate matching schemes reflecting the connection relationship between two-phase current and voltage are generated, the matching degree index of each candidate matching scheme is calculated, and the actual phase sequence relationship between voltage and current in the split-phase power grid is determined based on the maximum value of the matching degree index.

12. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 11, characterized in that, The data processing unit includes a voltage reconstruction module and an in-phase correlation matching module, wherein, The voltage reconstruction module is based on the input single-phase voltage signal. Based on the inherent symmetry characteristics of the split-phase AC power supply system, estimate the two possible signals of the other phase voltage. The voltage signal is obtained after reconstruction. , and Send to the same-phase correlation matching module; The in-phase correlation matching module includes: a permutation and combination unit, four split-matching degree calculators, and a matching correlation selector. The aforementioned combiner, based on a real but unknown voltage-current phase sequence matching relationship, combines two current signals... and With voltage signal , , By performing permutations and combinations, four possible voltage-current mapping schemes are generated, each characterized as defined in the following ways: , , , and will arrive The data are fed into four different crack matching degree calculators; The four split-match degree calculators each use a voltage-current mapping scheme. Using the input as the basis, calculate the crack matching degree index respectively. And send it to the matching relationship selector; The matching relationship selector, in particular, matches four split-match degree indices. to In the middle, select the maximum value. The mapping scheme corresponding to this value The voltage-current matching relationship represented is the actual phase sequence relationship between voltage and current in the split-phase power grid to be identified.

13. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 12, characterized in that, The split-matching degree calculator includes: two single-matching degree calculators and a summer, wherein the two single-matching degree calculators each take the phase sequence relationship of one phase in the voltage-current mapping scheme as input and use the single-matching degree function. The single-match degree measure of the input current and voltage is calculated and sent to the summer; the summer sums the single-match degree measure values ​​output by the two single-match degree calculators to calculate the split-match degree index corresponding to the phase sequence relationship. The single-match degree function It is a function related to the power factor.

14. The voltage and current phase sequence identification device based on single-phase voltage sampling as described in claim 13, characterized in that, The single-match degree function Defined as a power factor-based matching function, and a single matching degree function. The calculation formula is: , Formula 12, Alternatively, a single matching degree function Defined as a matching function based on power factor and current value, and a single matching degree function. The calculation formula is: , Formula 13, In formulas 2 and 3, , ,and The power factor PF is: , Formula 4, The active power P is: , Formula 5, The apparent power S is: , Formula 6, The effective voltage value RMS(U) is: , Formula 7, The effective value of the current, RMS(I), is: , Formula 8.

15. A voltage and current phase sequence identification method based on single-phase voltage sampling, characterized in that, The voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 11 to 14 is used, and the phase sequence identification method includes the following steps: Step 1: Signal Acquisition Voltage sampling: The voltage is sampled from any one phase of the two-phase line by a voltage sampling unit to obtain the single-phase voltage signal of that phase. And define the collected single-phase line as Phase, define the other unsampled phase line as Mutually; Current sampling: The current is sampled from the two phase lines by the current detection unit to obtain the current signal of the two phase lines. and And define the two phase lines corresponding to the current signal as follows: Harmony Mutually; Step 2: Data Processing Three-phase voltage reconstruction: Based on the symmetrical characteristics of split-phase AC power grids, and using the sampled single-phase voltage signals... Estimate the two possible signals of the other phase voltage. The specific steps are as follows: assumed And assume The phase of the first phase is the reference phase, with a phase of 0°. The voltage waveform of the other phase has two possibilities: phase lag. Phase 120° and Advanced With a phase angle of 120°, set the voltages of these two phases as follows: and Based on the above system conditions, the data processing unit can estimate the two possible voltage signals for this phase as follows: , In the formula, U m Where f is the voltage amplitude and f is the grid frequency; Voltage and current in-phase matching: Assume the mapping relationship σ:{x,y}→{a,b}or{a,c} is an injective function representing the pairing of current and voltage in each phase of a split-phase system. And define the split-phase matching degree index F(σ) to characterize the in-phase matching relationship between voltage and current in each phase as: , Formula 11, In the formula, the function It is a single-match degree function; Based on the four combinations of phase voltage and current pairing in a split-phase power grid, the split-phase matching degree index is calculated for each combination condition. , , , The values ​​are selected, and the maximum value is obtained to make... Mapping with the largest value This mapping The corresponding voltage-current mapping relationship is the actual voltage and current in-phase relationship.

16. A power detection method for a split-phase power grid, characterized in that, It uses a voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 11 to 14 for power detection.

17. A power detection method for a split-phase power grid, characterized in that, It uses the voltage and current phase sequence identification method based on single-phase voltage sampling as described in claim 15 to determine the phase sequence, and the power detection method includes the following steps: The current signals of the two phase lines are sampled using the current detection unit. and and the voltage signal sampled by the voltage sampling unit. Estimate the two possible signals for the other phase voltage. Finally, based on the phase sequence matching relationship of the identified voltage and current... Perform the calculation of the required power.

18. A power detector for a split-phase power grid, characterized in that, It uses the power detection method for split-phase power grids as described in claim 16 or 17.

19. A split-phase grid-connected power supply system, characterized in that, It uses a voltage and current phase sequence identification device based on single-phase voltage sampling as described in any one of claims 11 to 14.

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