Calibration system for large-scale earth screen power frequency characteristic parameter tester

Abstract

The utility model discloses a calibration system for a large-scale earth screen power frequency characteristic parameter tester. The calibration system comprises an auxiliary resistance box, a standard virtual impedance module and a voltage / current generating device. The auxiliary resistance box, the standard virtual impedance module and at least one measured instrument form a measuring loop; the auxiliary resistance box is used for providing at least one auxiliary resistor in the measuring loop; the standard virtual impedance module is used for providing at least one transmission impedance in the measurement loop; the voltage / current generating device is used for providing at least one interference signal in the measuring loop. According to the embodiment of the utility model, the transmission impedance of the active two-port network unit is adopted to replace an Re physical resistor and an Le physical inductor, and the interference voltage and the interference current are provided through the voltage / current generating device, so that on one hand, high-precision program control of the transmission impedance is realized through the transmission characteristics of the program-controlled active two ports; on the other hand, the grounding grid voltage output function and the shunting vector output function are integrated, and calibration is provided for grounding grid voltage measuring equipment and anti-interference.

Description

Technical Field

[0001] The utility model relates to the field of calibration systems, in particular to a calibration system for a large-scale grounding network power frequency characteristic parameter tester. Background Art

[0002] At present, the only relevant standard for the verification and calibration of grounding measuring instruments is JJG 366-2004 "Verification Procedure for Grounding Resistance Meters", which clearly states that it is not applicable to the verification of instruments related to large ground networks. The current DL / T845.2-2004 "General Technical Conditions for Resistance Measuring Devices - Power Frequency Grounding Resistance Tester" only proposes grounding resistance, but not grounding impedance, and there are no parameters such as shunt vector. It can be seen that the current standards lag seriously behind the development of instruments, and the relevant verification and calibration systems and platforms are also extremely lacking.

[0003] The Chinese utility model patent with announcement number CN209878978U discloses a metrological verification device for a ground impedance tester for a large grounding device. CN209878978U replaces the physical resistance to simulate the resistance part and replaces the physical inductance to simulate the reactance part through the transmission impedance of the active two-port network, and realizes high-precision program control of the transmission impedance by program-controlling the transmission characteristics of the active two-port network through the control device. It is not necessary to prepare physical resistance and physical inductance of various specifications according to the measuring range of the detector, and avoids the cumbersome operation of replacing physical resistance and physical inductance during verification, does not need to prepare precise physical inductance, and also avoids the physical inductance having poor stability and being greatly affected by environmental factors and working conditions.

[0004] The prior art such as CN209878978U only considers simulating the resistance and reactance of the measured ground network, but does not involve anti-interference experiments for impedance calibration, nor does it involve calibration of shunt and measured ground network voltage. Utility Model Content

[0005] The embodiment of the utility model discloses at least one calibration system of a large-scale ground network power frequency characteristic parameter tester, comprising an auxiliary resistance box, a standard virtual impedance module and a voltage / current generating device; the auxiliary resistance box, the standard virtual impedance module and at least one instrument under test form a measuring loop; the auxiliary resistance box is used to provide at least one auxiliary resistance in the measuring loop; the standard virtual impedance module is used to provide at least one transmission impedance in the measuring loop; the voltage / current generating device is used to provide at least one interference signal in the measuring loop.

[0006] In a preferred embodiment of the utility model, the auxiliary resistance box, the standard virtual impedance module and the current measuring part of the instrument under test form a current measurement loop; the auxiliary resistance box, the standard virtual impedance module and the voltage measuring part of the instrument under test form a voltage measurement loop; the auxiliary resistance box is used to provide at least one programmable resistor in the current measurement loop and / or the voltage measurement loop; the standard virtual impedance module is used to provide transmission impedance in the current measurement loop and / or the voltage measurement loop; and the voltage / current generating device provides an interference signal to the current measurement loop and / or the voltage measurement loop.

[0007] In a preferred embodiment of the utility model, the auxiliary resistor box at least includes a programmable resistor RC1, a programmable resistor RC2, a programmable resistor RP1 and a programmable resistor RP2; the C1 end of the instrument under test, the programmable resistor RC1, the standard virtual impedance module, the programmable resistor RC2 and the C2 end of the instrument under test sequentially constitute the current measurement circuit; the P1 end of the instrument under test, the programmable resistor RP1, the standard virtual impedance module, the programmable resistor RP2 and the P2 end of the instrument under test sequentially constitute the voltage measurement circuit.

[0008] In a preferred embodiment of the utility model, at least one of the programmable resistor RC1, the programmable resistor RC2, the programmable resistor RP1 and the programmable resistor RP2 is constructed as a programmable resistor group; the programmable resistor group includes at least two sub-programmable resistors connected in series in sequence; both sides of any sub-programmable resistor are coupled to the external output through at least one programmable switch.

[0009] In an embodiment of the utility model, the standard virtual impedance module includes an active two-port network unit; the current input end of the active two-port network is coupled to the programmable resistor RC1, the current output end is coupled to the programmable resistor RC2, the voltage output end is coupled to the programmable resistor RP1, and the voltage input end is coupled to the programmable resistor RP2.

[0010] In a preferred embodiment of the utility model, the standard virtual impedance module also includes a shunt current output circuit; the shunt current output circuit includes an adjustable resistor R9, an operational amplifier, an NPN transistor Q1 and a PNP transistor Q2; the positive input terminal of the operational amplifier is connected to the voltage output port P1-, the negative input terminal of the operational amplifier is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded and connected to the voltage output port P2-, and the connection point between the operational amplifier and the adjustable resistor R9 also serves as the negative output terminal of the shunt current output circuit; the output terminal of the operational amplifier is connected to the collectors of the NPN transistor Q1 and the PNP transistor Q2, and the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected to serve as the positive output terminal of the shunt current output circuit.

[0011] In a preferred embodiment of the utility model, the standard virtual impedance module unit also includes a voltage generating device; the voltage generating device includes an MCU controller, a DAC, a resistor R11, a resistor R3, an adjustable resistor R10, a resistor R8, a capacitor C2 and a capacitor C3, an operational amplifier A and an operational amplifier B; the MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the resistor R3 and one end of the capacitor C2, the other end of the resistor R3 is connected to the positive input end of the operational amplifier A, and the other end of the capacitor C2 is connected to the output end of the operational amplifier A; the positive input end of the operational amplifier A is also grounded after passing through the capacitor C3, and the negative input end of the operational amplifier A is connected to its output end; the output end of the operational amplifier A is connected to the positive input end of the operational amplifier B, the negative input end of the operational amplifier B is grounded after passing through the adjustable resistor R10, the resistor R8 is also connected between the negative input end and the output end of the operational amplifier, and the output end and the ground end of the operational amplifier B serve as the output end of the voltage generating device.

[0012] In a preferred embodiment of the utility model, the voltage / current generating device includes an interference signal generating circuit, a voltage conditioning signal circuit and a current signal conditioning circuit; the interference signal generating circuit includes: an MCU controller, a DAC, a resistor R2, a resistor R4, a capacitor C1, a capacitor C4 and an operational amplifier C; the MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the resistor R4 and one end of the capacitor C1, the other end of the resistor R4 is connected to the positive input end of the operational amplifier C, and the other end of the capacitor C1 is connected to the output end of the operational amplifier C; the positive input end of the operational amplifier C is also grounded after passing through the capacitor C4; the voltage conditioning signal circuit includes: a resistor R5, a resistor R6 and an operational amplifier D; the positive input end of the operational amplifier D is connected to the output end of the operational amplifier C, and the negative input end of the operational amplifier D is connected to the positive input end of the operational amplifier C. The input end is grounded after passing through the adjustable resistor R5, the resistor R6 is also connected between the negative input end and the output end of the operational amplifier, and the output end of the operational amplifier B serves as the output end of the voltage conditioning signal circuit; the current signal conditioning circuit includes: an adjustable resistor R9, an operational amplifier E, an NPN transistor Q3 and a PNP transistor Q4; the positive input end of the operational amplifier E is connected to the output end of the operational amplifier C, the negative input end of the operational amplifier E is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded, and the connection point between the operational amplifier E and the adjustable resistor R9 also serves as the negative output end of the current signal conditioning circuit; the output end of the operational amplifier E is connected to the collectors of the NPN transistor Q3 and the PNP transistor Q4, and the emitters of the NPN transistor Q3 and the PNP transistor Q4 are connected to serve as the positive output end of the current signal conditioning circuit.

[0013] In a preferred embodiment of the utility model, the voltage / current generating device is coupled between the auxiliary resistor box and the standard virtual impedance module; the voltage / current generating device is used to provide interference voltage to the voltage measurement loop portion between the auxiliary resistor box and the standard virtual impedance module.

[0014] In a preferred embodiment of the utility model, the instrument under test includes a tested excitation source, a tested shunt test host, and a tested shunt test slave; the tested excitation source, the tested shunt test host, the auxiliary resistance box, the standard virtual impedance module and the tested shunt test slave constitute the current measurement circuit; the voltage / current generating device provides interference current to the current measurement partial circuit between the standard virtual impedance module and the tested shunt test slave through a current coupling tool.

[0015] Compared with the prior art, the utility model adopts the transmission impedance of the active two-port network unit to replace the Re physical resistor and Le physical inductor, and provides interference voltage and interference current through the voltage / current generating device. On the first hand, the transmission characteristics of the program-controlled active two-port are used to realize high-precision program control of the transmission impedance; on the second hand, the problem that the Re physical resistor and Le physical inductor need to be prepared in various specifications according to the measuring range of the detector is solved; on the third hand, the cumbersome operation problem of replacing the Re physical resistor and Le physical inductor during measurement is avoided; on the fourth hand, the problem of temperature drift of the Re physical resistor and Le physical inductor is avoided; on the fifth hand, the ground grid voltage output function is integrated to provide calibration for the ground grid voltage measurement equipment, improve the system integration, simplify the calibration scheme of the large ground grid test system calibration, and improve work efficiency. On the sixth hand, the shunt vector output function is integrated to provide calibration for the shunt equipment. On the seventh hand, the on-site interference is simulated to realize the evaluation of the anti-interference ability of each parameter.

[0016] In view of the above-mentioned solutions, the present invention describes the exemplary embodiments disclosed in detail below with reference to the accompanying drawings, so that other features and advantages of the embodiments of the present invention are also made clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the utility model and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A model diagram showing the three-pole method used in the prior art to measure ground impedance.

[0019] Figure 2 A schematic structural diagram of an auxiliary resistor box according to an embodiment of the utility model is shown.

[0020] Figure 3 A schematic diagram showing the structure of an active two-port network unit and a shunt current output circuit.

[0021] Figure 4 A schematic structural diagram of a voltage generating device is shown.

[0022] Figure 5 A schematic structural diagram of a voltage / current generating device according to an embodiment of the utility model is shown.

[0023] Figure 6 A wiring diagram of a calibration system for a large-scale grounding network power frequency characteristic parameter tester according to this embodiment is shown.

[0024] Figure 7 Another wiring diagram of the calibration system of the large-scale grounding network power frequency characteristic parameter tester of this embodiment is shown. DETAILED DESCRIPTION

[0025] Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. Many specific details are shown in the following detailed description in order to provide a full understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments can be practiced without these specific details. In other cases, well-known methods, processes, components, circuits, and networks are not described in detail in order to avoid unnecessarily obscuring aspects of the embodiments.

[0026] To facilitate understanding of the embodiments of the present invention, the embodiments of the present invention take a large-scale ground impedance tester in the prior art as an example to illustrate the technical principle of the ground impedance of the large-scale ground impedance tester. Figure 1 A model diagram showing the three-pole method used in the prior art to measure ground impedance. Figure 1 It is shown that a large-scale ground impedance tester in the prior art includes a constant current source I, a voltmeter V, a current electrode C and a voltage electrode P. A test current Im is applied between the current electrode C and the ground network G to be tested through the constant current source I. The test current Im flows out from the current output terminal C1 of the ground impedance tester, is connected to the current electrode C through the test line, enters the ground, returns to the ground network to be tested through the earth, and then is connected to the current input terminal C2 of the ground impedance tester through the test line from the return point B of the ground network to be tested, forming a current loop. The voltmeter V measures the voltage Up generated by the test current Im between the voltage electrode P and the ground network to be tested; one port of the voltmeter V is the voltage input terminal P1 of the ground impedance tester, which is connected to the voltage electrode P through the test line; the other port of the voltmeter V is the voltage output terminal P2 of the ground impedance tester, which is connected to the return point B of the ground network to be tested through the test line. According to Ohm's law, the power frequency grounding impedance ZG of the ground network to be tested is UP / Im.

[0027] The utility model embodiment discloses a calibration system for a large-scale ground network power frequency characteristic parameter tester. The calibration system simulates the on-site measurement conditions and requirements of the ground network to be measured, realizes the calibration of the indication errors of parameters such as ground resistance, ground impedance (modulus value, angle), shunt vector (current amplitude and angle), and surface potential difference, and realizes the evaluation of the anti-interference ability of each parameter by simulating on-site interference. In addition, the calibration system fully complies with the detection methods and requirements of DL / T 845.2 and JJG ground impedance tester metrological verification regulations, and provides technical support for the value traceability of ground characteristic parameter power frequency measurement instruments.

[0028] The utility model discloses a large-scale grounding network power frequency characteristic parameter tester calibration system. The calibration system includes an auxiliary resistance box, a standard virtual impedance module and a voltage / current generating device. The auxiliary resistance box, the standard virtual impedance module and the instrument under test respectively form a voltage measurement loop and a current measurement loop.

[0029] The auxiliary resistance box is used to provide controllable programmable resistance in the voltage measurement loop and the current measurement loop respectively;

[0030] The standard virtual impedance module is used to provide controllable transmission impedance in the voltage measurement loop and the current measurement loop respectively.

[0031] The voltage / current generating device provides an interference signal to the current measuring loop and / or the voltage measuring loop.

[0032] Then, the combination of the auxiliary resistance box and the standard virtual impedance module can simulate the Re physical resistance and Le physical inductance of the ground grid, realize high-precision program control of the transmission impedance of the simulated ground grid, and can adapt to ground impedance testers of different specifications.

[0033] The auxiliary resistor box of the embodiment of the utility model comprises independently operated program-controlled resistors RC1, RC2, RP1 and RP2. Each program-controlled resistor is constructed as a program-controlled resistor group.

[0034] Figure 2 A schematic structural diagram of a programmable resistor group according to an embodiment of the utility model is shown. Figure 2 It is shown that the programmable resistor group includes multiple sub-programmable resistors, the beginning end of the first sub-programmable resistor is the input of the programmable resistor group, and the end of the last resistor is the output of the programmable resistor group. Both ends of each sub-programmable resistor are connected to the output of the programmable resistor group through a programmable switch, and the resistance change of the programmable resistor group is controlled by controlling the opening and closing of each programmable switch.

[0035] Based on this, the four programmable resistors in the embodiment of the utility model are respectively characterized as the analog resistors RP1, RP2, RC1 and RC2 of the connection lines with the current test holes P1, P2, C1 and C2 of the instrument under test. According to different settings, the device can set different resistance values ​​for RP1, RP2, RC1 and RC2, eliminating the trouble of rewiring the device.

[0036] The standard virtual impedance module of the embodiment of the utility model comprises an active two-port network unit shunt current output circuit and a voltage generating device.

[0037] Figure 3 A schematic diagram showing the structure of an active two-port network unit and a shunt current output circuit.

[0038] The active two-port network unit is used for the grounding impedance of the ground network. The active two-port network unit realizes high-precision program control of the transmission impedance of the analog ground network through a programmable gain amplifier, an adder, etc.

[0039] Preferably, the active two-port network unit of this embodiment can be configured as a network W disclosed in CN209878978U in the prior art.

[0040] The shunt current output circuit includes an adjustable resistor R9, an operational amplifier, an NPN transistor Q1 and a PNP transistor Q2. The positive input terminal of the operational amplifier is connected to the voltage output port P1-, the negative input terminal of the operational amplifier is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded and connected to the voltage output port P2-, and the connection point between the operational amplifier and the adjustable resistor R9 also serves as the negative output terminal of the shunt current output circuit. The output terminal of the operational amplifier is connected to the collectors of the NPN transistor Q1 and the PNP transistor Q2, and the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected to serve as the positive output terminal of the shunt current output circuit.

[0041] Figure 4 A schematic structural diagram of a voltage generating device is shown. Figure 4 The voltage generating device is shown to include: an MCU controller, a DAC, a resistor R11, a resistor R3, an adjustable resistor R10, a resistor R8, a capacitor C2 and a capacitor C3, an op amp A and an op amp B. The MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the resistor R3 and one end of the capacitor C2, the other end of the resistor R3 is connected to the positive input end of the op amp A, and the other end of the capacitor C2 is connected to the output end of the op amp A; the positive input end of the op amp A is also grounded after passing through the capacitor C3, and the negative input end of the op amp A is connected to its output end. The output end of the op amp A is connected to the positive input end of the op amp B, the negative input end of the op amp B is grounded after passing through the adjustable resistor R10, and a resistor R8 is also connected between the negative input end and the output end of the op amp. The output end and the ground end of the op amp B serve as the output end of the voltage generating device, and the grounding voltage can be calibrated using the output end voltage of the voltage generating device.

[0042] Based on this, the standard virtual impedance module of the embodiment of the utility model adopts the transmission impedance of the active two-port network unit to replace the Re physical resistor and Le physical inductor. On the first hand, the transmission characteristics of the program-controlled active two-port are used to realize high-precision program control of the transmission impedance; on the second hand, the problem that the Re physical resistor and Le physical inductor need to be prepared in various specifications according to the measuring range of the detector is solved; on the third hand, the cumbersome operation problem of replacing the Re physical resistor and Le physical inductor during measurement is avoided; on the fourth hand, the problem of temperature drift of the Re physical resistor and Le physical inductor is avoided; on the fifth hand, the ground grid voltage output function is integrated to provide calibration for the ground grid voltage measurement equipment, improve the system integration, simplify the calibration scheme of the large ground grid test system calibration, and improve work efficiency. On the sixth hand, the shunt vector output function is integrated to provide calibration for the shunt equipment.

[0043] Figure 5 A schematic structural diagram of a voltage / current generating device according to an embodiment of the utility model is shown. Figure 5 The voltage / current generating device is shown to include an interference signal generating circuit, a voltage conditioning signal circuit and a current signal conditioning circuit.

[0044] The interference signal generating circuit includes: an MCU controller, a DAC, a resistor R2, a resistor R4, a capacitor C1, a capacitor C4 and an operational amplifier C.

[0045] The MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the resistor R4 and one end of the capacitor C1, the other end of the resistor R4 is connected to the positive input end of the operational amplifier C, and the other end of the capacitor C1 is connected to the output end of the operational amplifier C; the positive input end of the operational amplifier C is also grounded after passing through the capacitor C4.

[0046] The voltage conditioning signal circuit includes resistor R5, resistor R6 and operational amplifier D.

[0047] The positive input terminal of the operational amplifier D is connected to the output terminal of the operational amplifier C, and the negative input terminal of the operational amplifier D is grounded after passing through the adjustable resistor R5. A resistor R6 is also connected between the negative input terminal and the output terminal of the operational amplifier. The output terminal of the operational amplifier B serves as the output terminal of the voltage conditioning signal circuit.

[0048] The current signal conditioning circuit includes an adjustable resistor R9, an operational amplifier E, an NPN transistor Q3 and a PNP transistor Q4.

[0049] The positive input terminal of the operational amplifier E is connected to the output terminal of the operational amplifier C, the negative input terminal of the operational amplifier E is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded, and the connection point between the operational amplifier E and the adjustable resistor R9 also serves as the negative output terminal of the current signal conditioning circuit; the output terminal of the operational amplifier E is connected to the collector of the NPN transistor Q3 and the PNP transistor Q4, and the emitters of the NPN transistor Q3 and the PNP transistor Q4 are connected to serve as the positive output terminal of the current signal conditioning circuit. After the interference signal generating circuit generates the interference wave signal, the voltage is programmed and output after power amplification is realized through the voltage conditioning signal circuit, and the current is programmed and output after power amplification is realized through the current conditioning signal circuit.

[0050] Based on this, the voltage / current generating device of this embodiment can provide interference voltage and interference current respectively, which can be used to be superimposed on the current measurement loop or the voltage measurement loop to simulate field interference to realize the evaluation of the anti-interference ability of each parameter.

[0051] Then, the embodiment of the utility model discloses a calibration system for a large-scale grounding network power frequency characteristic parameter tester. Each part in the calibration system can be wired according to different calibration functions to achieve metrological verification of the large-scale ground impedance tester.

[0052] For example, the first embodiment discloses a wiring method of a large-scale grounding network power frequency characteristic parameter tester calibration system, which can realize the calibration of the power frequency characteristic parameters of the instrument under test when there is an interference voltage.

[0053] Figure 6 A wiring diagram of a calibration system for a large-scale grounding network power frequency characteristic parameter tester according to this embodiment is shown. Figure 6 It is shown that one end C1+, C2+, P1+, P2+ of the programmable resistors RC1, RC2, RP1 and RP2 of the auxiliary resistor box are respectively connected to the current test holes C1, C2, P1 and P2 of the device under test. The other ends C1- and C2- of the programmable resistors RC1 and RC2 are respectively connected to the current input ports C1- and C2- of the standard virtual impedance to form the current detection circuit of the device under test. The other ends P1- and P2- of the programmable resistors RP1 and RP2 are respectively connected to the voltage output ports P1- and P2- of the standard virtual impedance to form the voltage detection circuit of the device under test. The voltage / current generating device is connected in series into the voltage detection circuit and outputs the interference voltage.

[0054] Based on this, after the calibration system is wired, no other wiring operations are required. Through software operation, the control of the three devices of standard virtual impedance, voltage / current generator and auxiliary resistance box can be realized, which simplifies the equipment wiring and makes the calibration operation more convenient. Among them, the auxiliary resistance box completes the setting of auxiliary resistors RC1, RC2, RP1, and RP2, and the voltage / current generator generates interference signals, which are superimposed on the measurement circuit to simulate the on-site interference environment of the instrument under test. When the anti-interference ability is not calibrated, this device can be disconnected. Finally, the standard virtual impedance generates the standard impedance for calibration. The three devices can be controlled individually through the interactive interface, or they can be connected to an external PC through the CAN network to achieve remote control and automatic calibration.

[0055] For example, embodiment 2 discloses another wiring method of a large-scale ground network power frequency characteristic parameter tester calibration system, which can realize shunt calibration of the ground impedance detection equipment of the tested excitation source, the tested shunt test host, and the tested shunt test slave.

[0056] Figure 7 Another wiring diagram of the calibration system of the large-scale grounding network power frequency characteristic parameter tester of this embodiment is shown. Figure 7 It is shown that one end C1+ of the first programmable resistor of the auxiliary resistor box is connected to one end of the detected excitation source, the other end of the detected excitation source is connected to one end of the host of the detected shunt test device, and the other end of the host of the detected shunt test device is connected to the C2+ end of the second programmable resistor; the other ends C1- and C2- of the first programmable resistor and the second programmable resistor are respectively connected to the two input ends of the standard virtual impedance. The output end of the virtual impedance outputs the shunt current to the current coupling fixture, and the voltage / current generating device outputs the interference current to the current coupling fixture. The shunt current and the interference current are coupled through the current coupling fixture and then output to the slave of the shunt test device to be tested.

[0057] Preferably, the current coupling fixture is generally a Rogowski coil test fixture, and the Rogowski coil sensor is passed through at the same time.

[0058] Based on this, after the calibration system is wired, no other wiring operations are required. Through software operation, the control of the three devices of standard virtual impedance, voltage / current generator, and auxiliary resistance box can be realized, which simplifies the equipment wiring and makes the calibration operation more convenient. Among them, the auxiliary resistance box completes the setting of auxiliary resistors RC1 and RC2, and the voltage / current generator generates current interference signals to simulate the on-site interference environment of the instrument under test. When the anti-interference ability is not calibrated, this device can be disconnected. The shunt current and interference current finally pass through the current coupling tooling, usually the Rogowski coil test tooling, and pass through the Rogowski coil sensor at the same time to achieve coupling. The standard virtual impedance generates the phase angle and shunt coefficient that control the shunt vector.

[0059] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large-scale grounding network power frequency characteristic parameter tester calibration system, characterized in that: It includes an auxiliary resistance box, a standard virtual impedance module and a voltage / current generating device; The auxiliary resistance box, the standard virtual impedance module and at least one instrument under test form a measurement loop; The auxiliary resistor box is used to provide at least one auxiliary resistor in the measurement loop; The standard virtual impedance module is used to provide at least one transmission impedance in the measurement loop; The voltage / current generating device is used to provide at least one interference signal in the measurement loop.

2. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 1 is characterized in that: The auxiliary resistance box, the standard virtual impedance module and the current measuring part of the instrument under test form a current measuring loop; The auxiliary resistance box, the standard virtual impedance module and the voltage measuring part of the instrument under test form a voltage measurement loop; The auxiliary resistor box is used to provide at least one programmable resistor in the current measurement loop and / or the voltage measurement loop; The standard virtual impedance module is used to provide transmission impedance in the current measurement loop and / or the voltage measurement loop; The voltage / current generating device provides an interference signal to the current measurement loop and / or the voltage measurement loop.

3. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 2 is characterized in that: The auxiliary resistor box at least includes a program-controlled resistor RC1, a program-controlled resistor RC2, a program-controlled resistor RP1 and a program-controlled resistor RP2; The C1 end of the instrument under test, the program-controlled resistor RC1, the standard virtual impedance module, the program-controlled resistor RC2 and the C2 end of the instrument under test sequentially form the current measurement loop; The P1 end of the instrument under test, the programmable resistor RP1, the standard virtual impedance module, the programmable resistor RP2 and the P2 end of the instrument under test sequentially form the voltage measurement loop.

4. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 2 is characterized in that: At least one of the program-controlled resistor RC1, the program-controlled resistor RC2, the program-controlled resistor RP1 and the program-controlled resistor RP2 is constructed as a program-controlled resistor group; The programmable resistor group includes at least two sub-programmable resistors connected in series in sequence; Both sides of any of the sub-programmable resistors are respectively coupled to an external output through at least one programmable switch.

5. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 2 is characterized in that: The standard virtual impedance module includes an active two-port network unit; The current input terminal of the active two-port network is coupled to the programmable resistor RC1 , the current output terminal is coupled to the programmable resistor RC2 , the voltage output terminal is coupled to the programmable resistor RP1 , and the voltage input terminal is coupled to the programmable resistor RP2 .

6. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 5 is characterized in that: The standard virtual impedance module also includes a shunt current output circuit; The shunt current output circuit includes an adjustable resistor R9, an operational amplifier, an NPN transistor Q1 and a PNP transistor Q2; The positive input terminal of the operational amplifier is connected to the voltage output port P1-, the negative input terminal of the operational amplifier is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded and connected to the voltage output port P2-, and the connection point between the operational amplifier and the adjustable resistor R9 also serves as the negative output terminal of the shunt current output circuit; The output end of the operational amplifier is connected to the collectors of the NPN transistor Q1 and the PNP transistor Q2, and the emitters of the NPN transistor Q1 and the PNP transistor Q2 are connected to serve as the positive output end of the shunt current output circuit.

7. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 5 is characterized in that: The standard virtual impedance module unit also includes a voltage generating device; The voltage generating device includes an MCU controller, a DAC, a resistor R11, a resistor R3, an adjustable resistor R10, a resistor R8, a capacitor C2 and a capacitor C3, an operational amplifier A and an operational amplifier B; The MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the resistor R3 and one end of the capacitor C2, the other end of the resistor R3 is connected to the positive input end of the operational amplifier A, and the other end of the capacitor C2 is connected to the output end of the operational amplifier A; the positive input end of the operational amplifier A is also grounded after passing through the capacitor C3, and the negative input end of the operational amplifier A is connected to its output end; The output end of the operational amplifier A is connected to the positive input end of the operational amplifier B, and the negative input end of the operational amplifier B is grounded after passing through the adjustable resistor R10. The resistor R8 is also connected between the negative input end and the output end of the operational amplifier. The output end and the ground end of the operational amplifier B serve as the output end of the voltage generating device.

8. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 1 is characterized in that: The voltage / current generating device comprises an interference signal generating circuit, a voltage conditioning signal circuit and a current signal conditioning circuit; The interference signal generating circuit comprises: an MCU controller, a DAC, a resistor R2, a resistor R4, a capacitor C1, a capacitor C4 and an operational amplifier C; The MCU controller is connected to the input end of the DAC, the output end of the DAC is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the resistor R4 and one end of the capacitor C1, the other end of the resistor R4 is connected to the positive input end of the operational amplifier C, and the other end of the capacitor C1 is connected to the output end of the operational amplifier C; the positive input end of the operational amplifier C is also grounded after passing through the capacitor C4; The voltage conditioning signal circuit includes: a resistor R5, a resistor R6 and an operational amplifier D; The positive input terminal of the operational amplifier D is connected to the output terminal of the operational amplifier C, the negative input terminal of the operational amplifier D is grounded after passing through the resistor R5, the resistor R6 is further connected between the negative input terminal and the output terminal of the operational amplifier, and the output terminal of the operational amplifier B serves as the output terminal of the voltage conditioning signal circuit; The current signal conditioning circuit includes: an adjustable resistor R9, an operational amplifier E, an NPN transistor Q3 and a PNP transistor Q4; The positive input terminal of the operational amplifier E is connected to the output terminal of the operational amplifier C, the negative input terminal of the operational amplifier E is connected to one end of the adjustable resistor R9, the other end of the adjustable resistor R9 is grounded, and the connection point between the operational amplifier E and the adjustable resistor R9 also serves as the negative output terminal of the current signal conditioning circuit; the output terminal of the operational amplifier E is connected to the collectors of the NPN transistor Q3 and the PNP transistor Q4, and the emitters of the NPN transistor Q3 and the PNP transistor Q4 are connected to serve as the positive output terminal of the current signal conditioning circuit.

9. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 2 is characterized in that: The voltage / current generating device is coupled between the auxiliary resistance box and the standard virtual impedance module; The voltage / current generating device is used to provide interference voltage in the voltage measurement loop portion between the auxiliary resistance box and the standard virtual impedance module.

10. The large-scale grounding network power frequency characteristic parameter tester calibration system according to claim 2, characterized in that: The instrument under test includes a tested excitation source, a tested shunt test host, and a tested shunt test slave; The tested excitation source, the tested shunt test host, the auxiliary resistance box, the standard virtual impedance module and the tested shunt test slave constitute the current measurement loop; The voltage / current generating device provides interference current to the current measurement partial loop between the standard virtual impedance module and the tested shunt test slave through the current coupling fixture.

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