Harmonic attenuation current generator for checking accuracy of current sensing device and checking method

Abstract

The invention discloses a harmonic attenuation current generator for checking the accuracy of a current sensing device and a checking method, and the harmonic attenuation current generator comprises a power transformer which is used for providing output voltages of different gears to a pre-energy-storage controlled second-order oscillation attenuation circuit; and the pre-energy-storage controlled second-order oscillation attenuation circuit is used for generating the oscillation current of the harmonic frequency meeting the checking requirement, synthesizing the oscillation current and outputting the synthesized oscillation current to the broadband current transformer to be checked. And the accuracy of the harmonic current sensing device is checked by comparing the collected and generated oscillation current waveform data with the harmonic detection result detected by the harmonic detector. According to the invention, the oscillation currents of the plurality of pre-energy-storage controlled second-order damped oscillation circuits are adopted to synthesize the test current applied to the primary side of the broadband current transformer during checking, so that the checking environment is closer to the actual operation environment of the broadband current transformer; therefore, the checking result can better represent the accuracy of the harmonic current sensing device in the actual operation environment.

Description

Technical Field

[0001] The invention belongs to the technical field of harmonic current measurement in power systems, and in particular relates to a harmonic decay current generator for calibrating the accuracy of a current sensor device and a calibration method. Background Art

[0002] Power system harmonics can cause abnormal heating, abnormal vibration, and accelerated insulation aging of electrical equipment, increase power system line losses, and may also lead to serious consequences such as explosion of parallel capacitors. In order to understand the harmonic situation of the power system, it is necessary to measure the harmonic currents of many branches of the power system, which requires the installation of a large number of devices that can accurately sense the harmonic currents of each order (hereinafter referred to as harmonic current sensing devices). In particular, with the access of various power electronic equipment to the power system, the frequency range of harmonic currents under the conditions of the new power system has become wider than before, which in turn requires the installed harmonic current sensing devices to have better broadband characteristics.

[0003] In fact, the harmonic current sensor device consists of two parts: a wideband current transformer and a harmonic detector. The output signal of the former is the input signal of the latter. Among them, the wideband current transformer, in addition to having the same function as the traditional electromagnetic current transformer to convert the fundamental large current into the fundamental small current and isolate the high voltage of the primary system, should have good wideband characteristics to transmit each harmonic current with sufficiently high accuracy. The harmonic detector, with many channels of high-speed and high-resolution A / D converters and a CPU with high-speed computing capabilities, is used for signal acquisition and calculation analysis, and gives the harmonic measurement results through the communication interface.

[0004] Harmonic current sensor devices must be calibrated for accuracy before they can be used. The existing accuracy calibration method for harmonic current sensor devices calibrates the wideband current transformer and the harmonic detector separately, and the actual calibration workload is very large. The reason is that whether it is the accuracy calibration of the wideband current transformer or the accuracy calibration of the harmonic detector, it is necessary to calibrate each harmonic current at different amplitudes. In addition, for the accuracy calibration of the wideband current transformer, since the input current amplitude is very large (such as: the fundamental current amplitude reaches hundreds of amperes, and the harmonic current amplitude reaches several amperes or even tens of amperes), the existing calibration method often only applies a single, constant amplitude fundamental current or a single frequency, constant amplitude harmonic current each time, which not only makes the calibration workload large, but also its calibration environment fails to simulate the actual operating conditions of the fundamental current superimposed with multiple frequency harmonic currents, which may lead to large deviations in the calibration results. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a harmonic attenuation current generator and a calibration method for accuracy calibration of a harmonic current sensor device, aiming to provide a calibration means for the accuracy calibration of the harmonic current sensor device with less calibration workload, higher calibration efficiency, and a calibration environment that is closer to actual operating conditions.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows: In one aspect, the present invention provides a harmonic decay current generator for accuracy verification of a current sensing device, comprising: a power transformer, at least one pre-storage energy controlled second-order oscillation decay circuit and a control and communication unit; The power transformer is used to provide output voltages of different gears to the pre-energy storage controlled second-order oscillation attenuation circuit; The pre-energy-storage controlled second-order oscillation attenuation circuit is used to generate an oscillating current with a harmonic frequency that meets the calibration requirements, and output it to the wide-band current transformer of the current sensor device to be calibrated after synthesis; the accuracy of the harmonic current sensor device is verified by collecting the oscillating current waveform data generated by the pre-energy-storage controlled second-order oscillation attenuation circuit and comparing it with the harmonic detection result of the wide-band current transformer to be verified; The control and communication unit is used to trigger the corresponding pre-energy storage controlled second-order oscillation attenuation circuit to turn on and off based on the instruction.

[0007] Preferably, The power transformer is a power frequency single-phase step-up transformer. The primary side of the power transformer is connected to an industrial frequency AC 220V power supply through a power switch; the secondary side of the power transformer is rated to output voltages of different gears; one end of the secondary winding of the power transformer is connected to the ground, and the other end selects a tap to output voltages of different gears according to the calibration requirements of different harmonic attenuation current amplitudes.

[0008] Preferably, the circuit structure of each of the pre-storage energy controlled second-order oscillation attenuation circuits is exactly the same; The pre-storage energy controlled second-order oscillation attenuation circuit is an RLC underdamped second-order circuit, and the pre-storage energy controlled second-order oscillation attenuation circuit includes a pre-storage energy controlled thyristor switch, a pre-storage energy capacitor, an oscillation controlled bidirectional thyristor switch, an oscillation inductor, a damping resistor, an oscillation capacitor and a non-inductive sampling resistor; The anode of the pre-energy storage control thyristor switch is connected to the selected gear end of the secondary side of the power transformer, and the cathode is connected to one end of the pre-energy storage capacitor, and the other end of the pre-energy storage capacitor is grounded; the oscillation control bidirectional thyristor switch T 11 and T 12Reverse parallel connection, one end after parallel connection is connected to the cathode of the pre-energy storage control thyristor switch, the other end after parallel connection is connected to one end of the oscillation inductor, the other end of the oscillation inductor is connected to one end of the oscillation capacitor, the other end of the oscillation capacitor is connected to one end of the non-inductive sampling resistor, and the other end of the non-inductive sampling resistor is connected to the primary side of the wide-band current transformer in the harmonic current sensing device to be calibrated.

[0009] Preferably, an energy-consuming resistor is connected in parallel to the oscillation capacitor of each of the pre-energy-storage controlled second-order oscillation attenuation circuits.

[0010] Preferably, the parameters of the pre-energy storage capacitor, oscillation inductor, damping resistor and oscillation capacitor in each of the pre-energy storage controlled second-order attenuation oscillation circuits are selected according to the frequency of the oscillation current required by the calibration, so that the frequency of the oscillation current of each pre-energy storage controlled second-order attenuation oscillation circuit is respectively the fundamental frequency and the harmonic frequencies required by the calibration.

[0011] Preferably, each of the pre-storage energy controlled second-order decay oscillator circuits is equipped with a waveform data acquisition unit, and the input voltage signal of the waveform data acquisition unit corresponds to the voltage across the two ends of the non-inductive sampling resistor. The waveform data acquisition unit is used to acquire waveform data of the oscillating current generated by the pre-energy storage controlled second-order decay oscillation circuit.

[0012] Preferably, the control and communication unit includes an embedded microcomputer system and a plurality of groups of thyristor trigger circuits; one group of thyristor trigger circuits correspondingly triggers a pre-storage energy controlled second-order oscillation attenuation circuit; The dedicated embedded microcomputer system is connected to the waveform data acquisition unit in the pre-energy storage controlled second-order oscillation attenuation circuit, and is used to control the waveform data acquisition unit to acquire and store oscillation current waveform data; In the group of thyristor trigger circuits, one thyristor trigger circuit is used to trigger the pre-energy storage controlled thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit, and two thyristor trigger circuits are used to trigger the oscillation controlled bidirectional thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit; The number of thyristor trigger circuits is configured according to the number of pre-energy storage controlled second-order oscillation attenuation circuits.

[0013] On the other hand, the present invention provides a method for calibrating the accuracy of a current sensor device containing a harmonic decay current generator based on the above-mentioned accuracy calibration of the current sensor device, comprising: Issue a calibration instruction to the control and communication unit to set the fundamental oscillation current and the harmonic oscillation current; Turn off the power switch, issue a pre-energy storage command to the control and communication unit, and trigger the pre-energy storage control thyristor switch in the corresponding pre-energy storage controlled second-order oscillation attenuation circuit to turn on through the thyristor trigger circuit based on the set fundamental oscillation current and harmonic oscillation current, so that the pre-energy storage capacitor stores energy; A start synchronization signal command is issued to the control and communication unit to control the data acquisition unit in the pre-energy storage controlled second-order oscillation attenuation circuit to start collecting waveform data and storing it, and a harmonic detector is controlled to start harmonic detection. Then, based on the set fundamental oscillation current and harmonic oscillation current, the oscillation control bidirectional thyristor switch in the corresponding pre-energy storage controlled second-order oscillation attenuation circuit is triggered to turn on through a thyristor trigger circuit to output an oscillation current; According to the verification requirements, after a certain period of time, a stop synchronization signal command is issued to the control and communication unit to control the harmonic detector to stop harmonic detection, and to stop triggering the oscillation control bidirectional thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit, so that the oscillation current is automatically shut down when it passes through zero; The waveform data collected by the data collection unit and the harmonic detection result of the harmonic detector are obtained, and the accuracy verification result of the harmonic current sensor device is obtained by comparison.

[0014] The present invention provides a harmonic decay current generator for checking the accuracy of a current sensor device, which has the following advantages: (1) The present invention adopts a pre-energy storage method to provide an oscillation power supply for an RLC underdamped second-order oscillation circuit, and only requires a small power transformer, without a high-power AC / DC switching power supply and a high-power amplifier, to generate an oscillation current with a large amplitude (for example, several hundred amperes). Compared with the technical solution of using an embedded system to generate a sinusoidal voltage signal and then amplifying the sinusoidal voltage signal through a high-power amplifier to output a large current, the present invention omits a high-power AC / DC switching power supply and a high-power amplifier, and does not require complex control, so the system is simpler, the cost is lower, and the operation is more reliable.

[0015] (2) The present invention utilizes the natural attenuation characteristics of the oscillating current of the RLC underdamped second-order oscillation circuit, so that one calibration test is equivalent to many calibration tests with adjusted amplitude in the traditional method, which greatly improves the efficiency of the calibration test.

[0016] (3) The present invention uses the oscillation current synthesis of multiple pre-energy-storage controlled second-order attenuation oscillation circuits (i.e., multiple RLC underdamped second-order oscillation circuits with different oscillation frequencies) to apply the test current to the primary side of the wide-band current transformer during calibration. Compared with the traditional calibration method, the calibration environment is closer to the actual operating environment of the wide-band current transformer, so that the calibration result can better represent the accuracy of the harmonic current sensor device under the actual operating environment.

[0017] (4) The oscillating currents of different oscillation frequencies generated by the multiple pre-energy storage controlled second-order attenuation oscillation circuits of the present invention use independent waveform data acquisition units to collect waveform data, making full use of the resolution of the A / D converter and ensuring the high accuracy of the waveform data of the fundamental current and each harmonic current of the harmonic attenuation current generator of the present invention, so as to be able to more accurately calibrate the accuracy of the harmonic current sensing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The main circuit diagram of the harmonic decay current generator provided by the present invention; Figure 2 A schematic diagram of a signal / communication interface of a control and communication unit in the present invention; Figure 3 It is the principle diagram of the thyristor trigger circuit in the present invention; Figure 4 It is a simulation waveform diagram of the time interval 0.8s≤t≤2.0s in the embodiment of the present invention; Figure 5 It is a simulation waveform diagram of the time interval 0.8s≤t≤0.82s in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The embodiments described below with reference to the accompanying drawings are illustrative and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0020] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by terms such as “upper”, “lower”, “front”, “rear”, “end”, “bottom” and “side” are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0021] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "installation" and the like should be understood in a broad sense, for example, it can be a fixed connection, a direct connection, or a connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0022] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0023] The specific embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings. The following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0024] The present invention provides a harmonic decay current generator for checking the accuracy of a current sensor device, the main circuit of which is as follows: Figure 1 As shown, the harmonic decay current generator consists of a power transformer T and n (n ≥ 1, for simplicity and convenience of description, Figure 1 Only the case of n=5 is given) Pre-storage energy controlled second-order oscillation attenuation circuit EOSC1-EOSC n Composition. Among them: The power transformer T is a power frequency single-phase step-up transformer. Its primary side: the rated input voltage is power frequency AC 220V, and it is connected to the power frequency AC 220V power supply through the power switch K; its secondary side: the rated output voltage is divided into 5 levels, for example, 1kV, 2kV, 3kV, 4kV and 5kV. One end of the secondary winding of the power transformer T is connected to the ground, and the other end can be selected according to the calibration needs of different harmonic attenuation current amplitudes. Tap ①, or tap ②, or tap ③, or tap ④, or tap ⑤ ( Figure 1 The figure shows the case of selecting tap ⑤). Tap ①, tap ②, tap ③, tap ④, tap ⑤ correspond to the secondary output voltage of 1kV, 2kV, 3kV, 4kV and 5kV respectively. The capacity of the power transformer T can be selected between 200VA and 1000VA, and the power frequency withstand voltage level between the primary and secondary sides is required to reach 10kV / 1min.

[0025] n pre-storage energy controlled second-order decay oscillator circuits EOSC1-EOSC n All of them are RLC underdamped second-order circuits, and their circuit structures are exactly the same, that is, each pre-storage energy controlled second-order attenuation oscillation circuit is composed of a pre-storage energy controlled thyristor switch, a pre-storage energy capacitor, an oscillation controlled bidirectional thyristor switch, an oscillation inductor, a damping resistor, an oscillation capacitor and a non-inductive sampling resistor. Figure 1 For example, see Figure 1 EOSC1's pre-storage energy control thyristor switch is S 11 , the pre-storage capacitor is C 11 , oscillation control bidirectional thyristor switch is T 11 and T 12 Reverse parallel, oscillating inductance is L 11 , the damping resistor is R 11 , the oscillation capacitor is C 12 and the non-inductive sampling resistor is R 12 .

[0026] Among them, the non-gear selection terminal of the secondary side of the power transformer T is grounded; the pre-storage energy controls the thyristor switch S11 The anode is connected to the selected gear end of the secondary side of the power transformer T, and its cathode is connected to the pre-storage capacitor C 11 One end of the pre-storage capacitor C 11 The other end of the oscillation control bidirectional thyristor switch T 11 and T 12 Reverse parallel connection, one end of the parallel connection is connected to the pre-storage energy control thyristor switch S 11 The cathode is connected to the other end of the parallel connection with the oscillating inductor L 11 One end of the oscillating inductor L 11 The other end of the oscillation capacitor C 12 One end of the oscillation capacitor C 12 The other end of the non-inductive sampling resistor R 12 One end is connected to the non-inductive sampling resistor R 12 The other end is connected to SWA1, SWA1 is connected to the primary side of the wide-band current transformer in the harmonic current sensing device to be calibrated, there is a wire between SWA1 and SWA2, and SWA2 is grounded.

[0027] It should be noted that each oscillation capacitor is connected in parallel with a large resistance (such as 1MΩ) energy-consuming resistor, which does not affect the oscillation characteristics and is used to consume the remaining energy of the oscillation capacitor. Figure 1 The energy dissipation resistor is not shown.

[0028] It should be noted that the parameters of the pre-storage capacitor, oscillation inductor, damping resistor and oscillation capacitor in each pre-storage controlled second-order decay oscillation circuit must be selected according to the required oscillation current frequency so that the oscillation current of EOSC1 i f1 The frequency is the fundamental frequency f 1. Oscillation current of EOSC2 i f2 The frequency is the harmonic frequency f 2. Oscillation current of EOSC3 i f3 The frequency is the harmonic frequency f 3. EOSC n Oscillating current i fn The frequency is the harmonic frequency f n , and there are: f 1≠ f 2≠ f 3≠......≠ f n .

[0029] It should be noted that EOSC1-EOSC nThe thyristor components in the respective pre-storage controlled thyristor switches and oscillation controlled bidirectional thyristor switches are selected according to the current size of the loop, the reverse withstand voltage requirements, and the frequency of the oscillation current. These contents are well known to those skilled in the electrical / electronic field and will not be elaborated here; EOSC1-EOSC n The selection of the parameters of the respective non-inductive sampling resistors needs to be considered with Figure 1 Waveform data acquisition unit DAU1-DAU shown n The analog conditioning circuits, A / D converters, etc. in the device are matched one by one. These contents are also well known to technicians in the electrical / electronic fields and are omitted here.

[0030] EOSC1-EOSC of the present invention n Each pre-storage controlled second-order decay oscillator circuit is equipped with a waveform data acquisition unit. Figure 1 ,EOSC1-EOSC n Configure waveform data acquisition units DAU1-DAU one by one n , and DAU1-DAU n The input voltage signal corresponds to the non-inductive sampling resistor R 12 -R n2 The voltage across the two ends of Figure 1 Only the case of n=5 is shown.

[0031] The input signal of the waveform data acquisition unit is the voltage across the non-inductive sampling resistor, which is proportional to the oscillating current flowing through the non-inductive sampling resistor. n One-to-one correspondence is used to collect EOSC1-EOSC n Waveform data of the oscillating current.

[0032] Specifically, the waveform data acquisition unit includes an analog conditioning circuit, a high-speed and high-resolution A / D converter, a CPU with high-speed computing capability, an optical fiber synchronization signal interface, an optical fiber serial communication interface, and a working power supply with an isolation transformer with a power frequency withstand voltage level of 10kV / 1min. Figure 1 Taking DAU1 matched with EOSC1 as an example, the optical fiber synchronization signal input interface of DAU1 is SS1, the transmission signal interface of the optical fiber serial communication interface is TX1, and the receiving signal interface of the optical fiber serial communication interface is RX1; see Figure 1 and Figure 2 , SS1, TX1, and RX1 of DAU1 are connected to Figure 2 The control shown is connected to SS1, TX1, and RX1 of the communication unit. The actual circuit design of the waveform data acquisition unit belongs to the conventional knowledge content in the electrical / electronic field and will not be described here.

[0033] In the present invention, a control and communication unit is also configured to match the main circuit. Figure 1 The main circuit with five pre-storage energy controlled second-order decay oscillator circuits and the supporting control and communication unit (hereinafter referred to as "[n=5] control and communication unit" for simplicity) is shown in the figure. Figure 2 shown. Figure 2 The circuit structure of the [n=5] control and communication unit is not shown in detail, so it is described in words here: the [n=5] control and communication unit is a dedicated embedded microcomputer system with a thyristor trigger circuit, which should be equipped with a high-performance CPU, various types of memory with sufficient capacity (including program memory, non-volatile data memory and random data memory), 5 optical fiber synchronization signal (output) interfaces, 5 optical fiber serial communication interfaces, 1 network communication interface, 15 thyristor trigger circuits and a working power supply. Among them:

n=5

[0034]

n=5

[0035] The thyristor trigger signal in the control and communication unit is sent by the optical fiber signal transmitter of the aforementioned dedicated embedded system and transmitted to the input end of the optical fiber signal receiver LT of the thyristor trigger circuit through the optical fiber (see Figure 3 ). The thyristor trigger circuit converts the light trigger signal into an electrical trigger signal and amplifies the power of the electrical trigger signal to trigger the thyristor with sufficient power. The thyristor trigger circuit proposed by the present invention is as follows Figure 3 shown.

[0036] Figure 3 The thyristor trigger circuit shown in the figure has a trigger power transformer with a ratio of 220V / 6V, a capacity of 15VA, and a power frequency withstand voltage level of 10kV / 1min between the source and the receiver. The source power voltage is 220V AC, and the output of the receiver is 6V AC. The diode rectifier bridge composed of D1-D4 rectifies the AC voltage into DC voltage. The 1N4007 diode can be selected for D1-D4. The filter capacitors C1 and C2 play a filtering role, so that the no-load voltage after filtering is V (about 8.5V), the voltage under load is about 8V, C1 can choose 4700μF / 50V electrolytic capacitor, C2 can choose 1μF / 63V monolithic capacitor. z The voltage regulator Z and the voltage regulator Z form a voltage regulator power supply to provide power to the optical fiber signal receiver LT. The voltage regulator Z can be a voltage regulator with a voltage of 5.6V and a power of 1W. The resistor R z According to the current selection of the voltage regulator tube Z, for example, the current is 90mA, because the power supply voltage is about 8V, so, R z The optical fiber signal receiver LT is used to convert the optical signal into a low-level electrical signal. Its function is equivalent to that of an optically controlled NPN transistor. Its working power supply is 5V. Agilent multimode optical fiber signal receiver can be selected. Transistor T g It is used to provide trigger current and is of PNP type. A PNP transistor with a maximum collector current of 250mA and a voltage of 50V can be selected. b1 and R b2A voltage divider is formed to turn on transistor T g Provide base current, assuming that the Vce of the transistor is -0.6V when it is saturated and turned on. , the thyristor trigger circuit is 150mA, then the base current can be designed to be 2.5mA and R b1 5.1kΩ, R b2 2.7kΩ (considering the 0.3V conduction voltage drop of the optical fiber signal receiver LT). Diode D5 is used to protect the transistor T g , 1N4007 can be selected. g Assuming that the equivalent resistance between the thyristor control electrode and the cathode is 15Ω, and the trigger current is limited to 150mA, the R g The above design contents are also well known to those skilled in the art in the field of electrical / electronic technology and are only used for illustration and are not the contents of the present invention.

[0037] The above design Figure 3 The thyristor trigger circuit shown in the figure, when the optical fiber signal receiver LT receives the optical fiber signal, the transistor T g turns on, thereby triggering the thyristor to turn on.

[0038] It should be noted that in the prior art, there are many forms of thyristor trigger circuits, which can meet the thyristor trigger requirements of the present invention through appropriate interface coordination design. Since the design of thyristor trigger circuits belongs to the common knowledge in the field of electrical / electronic technology, they will not be described in detail here.

[0039] The working principle of the above harmonic decay current generator is as follows: Pre-storage energy controlled second-order attenuation oscillation circuit EOSC1-EOSC n The synthetic oscillating current output is Figure 1 The SWA1 terminal shown in the figure enters the primary side of the wide-band current transformer in the harmonic current sensor device to be calibrated, and flows out from the SWA2 terminal; the output port of the wide-band current transformer is connected to the signal input port of the harmonic detector through a signal line; the network port of the harmonic detector is connected to the HUB ( Figure 1 The network port of the control and communication unit is connected to the HUB (not shown) of the calibration management computer through a network cable. Figure 2 The synchronization signal, serial communication interface, and trigger signal of the control and communication unit are connected to the main circuit according to the connection relationship described in "(I) Circuit Principle" of this specification.

[0040] In the embodiment of the present invention, the calibration management computer is used to perform calibration settings, issue pre-storage commands, start synchronization signals, trigger oscillation, read data, compare and analyze data, and provide calibration results. The calibration test process is as follows: S1. The calibration management computer issues calibration settings to the control and communication unit through network communication, i.e., selects the fundamental oscillation current and the harmonic oscillation current. For example, select Figure 1 The oscillation current of EOSC1-EOSC4 in.

[0041] S2, manual closing Figure 1 The power switch K in the control and communication unit is turned on, and the verification management computer issues a pre-energy storage command to the control and communication unit through network communication. Then, according to the oscillation current selected by S1, the control and communication unit sends a trigger signal CS 11 , CS 21 , CS 31 , CS 41 ,but Figure 1 S 11 , S 21 , S 31 , S 41 is triggered to conduct, the pre-energy storage capacitor C 11 , C 21 , C 31 , C 41 Energy storage; because the oscillation current of EOSC5 is not selected, S 51 No trigger signal, no conduction, pre-storage capacitor C 51 No energy storage. Here, after waiting for a certain period of time, such as 2s, to allow the pre-storage capacitor to complete energy storage, the control and communication unit stops triggering the signal CS 11 , CS 21 , CS 31 , CS 41 , S 11 , S 21 , S 31 , S 41 It automatically shuts down during the negative half cycle of the power supply voltage.

[0042] S3, the calibration management computer sends a start-up synchronization signal command to the control and communication unit through network communication, and starts the harmonic detector to start harmonic detection. Therefore, according to the oscillation current selected by S1, the control and communication unit sends a synchronization signal to DAU1-DAU4, and DAU1-DAU4 starts waveform data acquisition and stores the acquired data; the harmonic detector starts harmonic detection and continuously records the detection results. Then, the control and communication unit sends a trigger signal to (CT 11 -CT 12 )、(CT 21 -CT 22 )、(CT 31 -CT32 )、(CT 41 -CT 42 ), so that the thyristor pair (T 11 -T 12 )、(T 21 -T 22 )、(T 31 -T 32 )、(T 41 -T 42 ) is triggered to conduct, and EOSC1-EOSC4 outputs an oscillating current. It should be pointed out that the purpose of starting DAU1-DAU4 and the harmonic detector first is to collect a waveform before the oscillating current appears, so as to ensure that the initial part of the oscillating current data can be reliably recorded.

[0043] S4. According to the specific calibration requirements, after a certain period of time (e.g. 2s), the calibration management computer sends a stop synchronization signal command to the control and communication unit through network communication to stop the harmonic detector from detecting harmonics. Then, the control and communication unit stops triggering the signal pair (CT 11 -CT 12 )、(CT 21 -CT 22 )、(CT 31 -CT 32 )、(CT 41 -CT 42 ), so that the thyristor pair (T 11 -T 12 )、(T 21 -T 22 )、(T 31 -T 32 )、(T 41 -T 42 ) automatically shuts down when the corresponding oscillating current passes through zero, so that EOSC1-EOSC4 stops outputting the oscillating current. It should be noted that because each oscillating capacitor is connected in parallel with a large resistance (such as 1MΩ) energy-consuming resistor, the remaining energy of the oscillating capacitor is stored in the thyristor pair (T 11 -T 12 )、(T 21 -T 22 )、(T 31 -T 32 )、(T 41 -T 42 ) will be automatically shut down, and the energy will be consumed in the energy dissipation resistor, ready for the next calibration test.

[0044] S5. The calibration management computer forwards and reads the waveform data stored in DAU1-DAU4 through network communication and the control and communication unit; and reads the harmonic detection result of the harmonic detector through network communication.

[0045] S6. After reading the waveform data stored in DAU1-DAU4 and the harmonic detection results of the harmonic detector, the calibration management computer first needs to time-align the waveform data stored in DAU1-DAU4 with the harmonic detection results of the harmonic detector; then, the DFT algorithm and the waveform data are used to calculate the oscillation current i f1 , i f2 , i f3 , i f4 frequency, amplitude and phase; finally, the calculated results are compared and analyzed with the harmonic detection results of the harmonic detector to obtain the accuracy verification results of the harmonic current sensor device. Since the software algorithm in the verification computer does not belong to the content of the present invention, the contents of the above-mentioned time alignment algorithm, DFT algorithm and comparative analysis algorithm are omitted here. It must be emphasized here: because the oscillating current output by the harmonic attenuation current generator used for accuracy verification of the harmonic current sensor device of the present invention is naturally attenuated, one verification test is equivalent to many verification tests of adjusting the amplitude in the traditional method, which greatly improves the efficiency of the verification test.

[0046] It should be pointed out that for the sake of clarity, the above description is given by way of examples. For situations different from the examples given, refer to the above analogies.

[0047] In order to further illustrate the oscillation current waveform of the pre-storage energy controlled second-order decay oscillator circuit of the present invention, in one embodiment of the present invention, Figure 1 In the case of n=5 shown in the figure, under the condition that the T-side winding of the power transformer is set to 5kV, a group of component parameters of a pre-storage controlled second-order decay oscillation circuit are selected for time domain simulation. The selected circuit component parameters are as follows: EOSC1:C 11 =500μF, C 12 =340μF, R 11 =0.01Ω, L 11 =0.05H; fundamental wave.

[0048] EOSC2:C 21 =500μF, C 22 =11.5μF, R 21 =0.01Ω, L 21 =0.1H; 3rd harmonic.

[0049] EOSC3:C 31 =500μF, C 32 =4μF, R 31 =0.01Ω, L31 =0.052H; 7th harmonic.

[0050] EOSC4:C 41 =500μF, C 42 =2.5μF, R 41 =0.01Ω, L 41 =0.033H; 11th harmonic.

[0051] EOSC5:C 51 =500μF, C 52 =1.1μF, R 51 =0.01Ω, L 51 =0.021H; 21st harmonic.

[0052] The time domain simulation results are as follows Figure 4 (Time interval: 0.8s≤t≤2.0s) and Figure 5 (Time interval: 0.8s≤t≤0.82s). It can be seen that the oscillation current output by EOSC1-EOSC5 is consistent with the design target, which further illustrates the feasibility of the present invention.

[0053] It should be pointed out that the above simulation embodiments are only used to illustrate the feasibility of the present invention, and are not used to limit the selection range of component parameters of the pre-energy storage controlled second-order decay oscillator circuit of the present invention.

[0054] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0055] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0056] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0057] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A harmonic decay current generator for accuracy verification of a current sensing device, characterized in that: include: A power transformer, at least one pre-storage controlled second-order oscillation attenuation circuit and a control and communication unit; The power transformer is used to provide output voltages of different gears to the pre-energy storage controlled second-order oscillation attenuation circuit; The pre-energy-storage controlled second-order oscillation attenuation circuit is used to generate an oscillating current with a harmonic frequency that meets the calibration requirements, and output it to the wide-band current transformer of the current sensing device to be calibrated after synthesis; By collecting the oscillation current waveform data generated by the pre-energy storage controlled second-order oscillation attenuation circuit and comparing it with the harmonic detection result of the wide-band current transformer to be verified, the accuracy of the harmonic current sensor device is verified; The control and communication unit is used to trigger the corresponding pre-energy storage controlled second-order oscillation attenuation circuit to turn on and off based on the instruction.

2. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 1, characterized in that: The power transformer is a power frequency single-phase step-up transformer. The primary side of the power transformer is connected to an industrial frequency AC 220V power supply through a power switch; the secondary side of the power transformer is rated to output voltages of different gears; one end of the secondary winding of the power transformer is connected to the ground, and the other end selects a tap to output voltages of different gears according to the calibration requirements of different harmonic attenuation current amplitudes.

3. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 2, characterized in that: The circuit structure of each of the pre-storage energy controlled second-order oscillation attenuation circuits is exactly the same; The pre-storage energy controlled second-order oscillation attenuation circuit is an RLC underdamped second-order circuit, and the pre-storage energy controlled second-order oscillation attenuation circuit includes a pre-storage energy controlled thyristor switch, a pre-storage energy capacitor, an oscillation controlled bidirectional thyristor switch, an oscillation inductor, a damping resistor, an oscillation capacitor and a non-inductive sampling resistor; The anode of the pre-energy storage control thyristor switch is connected to the selected gear end of the secondary side of the power transformer, and the cathode is connected to one end of the pre-energy storage capacitor, and the other end of the pre-energy storage capacitor is grounded; the oscillation control bidirectional thyristor switch T 11 and T 12 Reverse parallel connection, one end after parallel connection is connected to the cathode of the pre-energy storage control thyristor switch, the other end after parallel connection is connected to one end of the oscillation inductor, the other end of the oscillation inductor is connected to one end of the oscillation capacitor, the other end of the oscillation capacitor is connected to one end of the non-inductive sampling resistor, and the other end of the non-inductive sampling resistor is connected to the primary side of the wide-band current transformer in the harmonic current sensing device to be calibrated.

4. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 3, characterized in that: An energy-consuming resistor is connected in parallel to the oscillation capacitor of each of the pre-energy-storage controlled second-order oscillation attenuation circuits.

5. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 3, characterized in that: The parameters of the pre-energy storage capacitor, oscillation inductor, damping resistor and oscillation capacitor in each of the pre-energy storage controlled second-order attenuation oscillation circuits are selected according to the frequency of the oscillation current required for calibration, so that the frequencies of the oscillation currents of each pre-energy storage controlled second-order attenuation oscillation circuit are respectively the fundamental frequency and the harmonic frequencies required for calibration.

6. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 3, characterized in that: Each of the pre-storage energy controlled second-order decay oscillator circuits is equipped with a waveform data acquisition unit, and the input voltage signal of the waveform data acquisition unit corresponds to the voltage across the two ends of the non-inductive sampling resistor. The waveform data acquisition unit is used to acquire waveform data of the oscillating current generated by the pre-energy storage controlled second-order decay oscillation circuit.

7. The harmonic decay current generator for accuracy verification of a current sensor device according to claim 6, characterized in that: The control and communication unit includes an embedded microcomputer system and multiple groups of thyristor trigger circuits; one group of thyristor trigger circuits correspondingly triggers a pre-storage energy controlled second-order oscillation attenuation circuit; The dedicated embedded microcomputer system is connected to the waveform data acquisition unit in the pre-energy storage controlled second-order oscillation attenuation circuit, and is used to control the waveform data acquisition unit to acquire and store oscillation current waveform data; In the group of thyristor trigger circuits, one thyristor trigger circuit is used to trigger the pre-energy storage controlled thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit, and two thyristor trigger circuits are used to trigger the oscillation controlled bidirectional thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit; The number of thyristor trigger circuits is configured according to the number of pre-energy storage controlled second-order oscillation attenuation circuits.

8. A method for calibrating the accuracy of a current sensor device containing a harmonic decay current generator based on the accuracy calibration of the current sensor device according to any one of claims 1 to 7, characterized in that: include: Issue a calibration instruction to the control and communication unit to set the fundamental oscillation current and the harmonic oscillation current; Turn off the power switch, issue a pre-energy storage command to the control and communication unit, and trigger the pre-energy storage control thyristor switch in the corresponding pre-energy storage controlled second-order oscillation attenuation circuit to turn on through the thyristor trigger circuit based on the set fundamental oscillation current and harmonic oscillation current, so that the pre-energy storage capacitor stores energy; A start synchronization signal command is issued to the control and communication unit to control the data acquisition unit in the pre-energy storage controlled second-order oscillation attenuation circuit to start collecting waveform data and storing it, and a harmonic detector is controlled to start harmonic detection. Then, based on the set fundamental oscillation current and harmonic oscillation current, the oscillation control bidirectional thyristor switch in the corresponding pre-energy storage controlled second-order oscillation attenuation circuit is triggered to turn on through a thyristor trigger circuit to output an oscillation current; According to the verification requirements, after a certain period of time, a stop synchronization signal command is issued to the control and communication unit to control the harmonic detector to stop harmonic detection, and to stop triggering the oscillation control bidirectional thyristor switch in the pre-energy storage controlled second-order oscillation attenuation circuit, so that the oscillation current is automatically shut down when it passes through zero; The waveform data collected by the data collection unit and the harmonic detection result of the harmonic detector are obtained, and the accuracy verification result of the harmonic current sensor device is obtained by comparison.

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