A signal amplification adapter for grid upgrading

Abstract

The application belongs to the technical field of signal amplifiers, and particularly relates to a signal amplification adapter for power grid upgrading and reconstruction, which comprises a power module, a filtering module, an input adjusting module, a three-phase and zero sequence operational amplifier module, a phase detection and correction module and an output protection module. The input adjusting module comprises a filtering unit, which is connected with A-phase output, B-phase output, C-phase output and zero sequence signal respectively for filtering out high harmonic interference. The phase detection and correction module comprises a phase detection unit and a phase correction unit. The input of the phase detection unit is connected with the output of the three-phase and zero sequence operational amplifier module for detecting phase difference. The input of the phase correction unit is connected with the output of the phase detection unit for correcting phase difference. Through use of the application, matching work of electronic voltage sensors and electromagnetic electric meters under voltage characteristics in Southeast Asia can be realized.

Description

Technical Field

[0001] This invention belongs to the field of signal amplifier technology, and in particular relates to a signal amplifier adapter for power grid upgrading and transformation. Background Technology

[0002] In high-voltage power systems, voltage measurement is a core component of power metering, system monitoring, fault diagnosis, and safe operation and maintenance. Its measurement accuracy and compatibility directly determine the stability and reliability of the power grid. With the rapid iteration of smart grid technology, digitalization and intelligence have become the core trends in the development of power equipment. Electronic voltage transformers (EVTs), with their significant technological advantages, have gradually replaced traditional sensors and become the mainstream measurement equipment in the current high-voltage power field. The power grid in Southeast Asia is also gradually promoting upgrades and transformations centered on EVT applications to help improve the level of power grid intelligence, while simultaneously strengthening the grid structure and operational reliability in conjunction with the construction of regional power grid interconnection.

[0003] Traditional electromagnetic voltage sensors are designed based on the principle of electromagnetic induction, with a fixed output voltage standard of 100V / √3 (approximately 57.735V). Electromagnetic meters used in conjunction with these sensors have long been employed in Southeast Asia, forming the core system for electricity metering and monitoring in the local power grid. However, these sensors suffer from drawbacks such as large size, limited accuracy, and high maintenance costs, making them unsuitable for the digital development needs of smart grids. EVT, as a new type of voltage measurement device, has a standardized output voltage standard of 3.25V / √3 (approximately 1.875V), precisely matching the input interface of electronic meters. It boasts advantages such as high accuracy, small size, and digital output, making it a core choice for upgrading and transforming Southeast Asian power grids.

[0004] Since Southeast Asia is largely an underdeveloped region with limited economic resources, replacing both traditional electromagnetic voltage sensors and electromagnetic meters during power grid upgrades would create enormous economic challenges. Therefore, local power grid upgrades typically adopt a "replace only the sensor, retain the existing electromagnetic meter" approach. While this reduces upgrade costs, it directly leads to a core problem—the incompatibility between electronic voltage sensors and electromagnetic meters. The output voltage of the EVT (3.25V / √3) differs significantly from the standard input voltage of the electromagnetic meter (100V / √3). Direct connection between the two will prevent the meter from properly acquiring signals, achieving inaccurate metering, and may even damage meter components.

[0005] To address the aforementioned matching issues, EVT amplifier adapters were developed. However, existing adapters struggle to adapt to the wide AC input characteristics of Southeast Asian power grids. The uneven development of power grids across Southeast Asian countries results in significant voltage fluctuations and a substantial demand for wide AC input. Existing adapters, mostly designed with fixed input specifications, cannot flexibly adapt to varying voltage fluctuations in power grid conditions. This leads to signal interruptions and decreased accuracy after connection, failing to meet the actual operational needs of local power grids. Furthermore, during operation, EVT amplifier adapters are affected by factors such as the characteristic deviations of internal operational amplifiers and power amplification modules, circuit delays, and temperature drift caused by the high temperature and humidity environment of Southeast Asia, resulting in slight phase shifts. Although these phase shifts are small, they disrupt signal phase consistency, affecting not only the compatibility stability between the EVT and electromagnetic meters but also interfering with the accuracy of power metering, leading to power calculation errors.

[0006] Furthermore, the widespread use of nonlinear loads (such as motors and rectifiers) and small power generation devices in Southeast Asia leads to significant harmonic pollution in the power grid, primarily consisting of the 5th, 7th, and 11th harmonics. The total harmonic distortion (THD) consistently ranges from 8% to 12%, far exceeding the ideal power grid standard. These harmonics are transmitted through the power grid to the EVT (Electronic Voltage Transmitter), mixing with the fundamental signal and entering the adapter. This not only interferes with the adapter's normal operation, resulting in decreased compatibility, but also transmits to electromagnetic meters, causing metering errors and reading deviations, affecting the fairness of electricity trade settlements and hindering the improvement of metering accuracy after power grid upgrades.

[0007] In summary, the upgrading of the Southeast Asian power grid presents challenges in matching electronic voltage sensors with electromagnetic meters, and the EVT amplifier adapter is unable to adapt to the large voltage fluctuation range and severe harmonic pollution of the Southeast Asian power grid, resulting in reduced accuracy of electricity metering. Summary of the Invention

[0008] The purpose of this invention is to provide a signal amplification adapter for power grid upgrading and transformation, aiming to achieve matching between electronic voltage sensors and electromagnetic meters under the voltage characteristics of Southeast Asia.

[0009] To achieve the above objectives, this invention provides a signal amplification adapter for power grid upgrading and transformation, comprising a power supply module, a filtering module, an input regulation module, a three-phase and zero-sequence operational amplifier module, a phase detection and correction module, and an output protection module, wherein: The power module is used to provide the low-voltage power supply signal required for the amplifier adapter to operate; The input of the input adjustment module is connected to the A-phase output, B-phase output, and C-phase output collected by the electronic voltage sensor. It is used to perform preliminary adjustment on the original three-phase voltage signal and the original zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal. The output of the input adjustment module is connected to the three-phase and zero-sequence operational amplifier module, which is used to amplify the power of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal. The output of the three-phase and zero-sequence operational amplifier module is connected to the input of the phase detection and correction module to correct the phase deviation of the third three-phase voltage signal and the third zero-sequence signal, so as to obtain the final three-phase voltage signal and the final zero-sequence signal. The output protection module is connected to the output of the phase detection and correction module, and is used to provide surge protection for the input adjustment module, the three-phase and zero-sequence operational amplifier module and the phase detection and correction module. The input adjustment module includes four parallel cascaded filtering units, which are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal to filter out high-order harmonic interference. The phase detection and correction module includes a phase detection unit and a phase correction unit. The input of the phase detection unit is connected to the output of the three-phase and zero-sequence operational amplifier module, and is used to detect the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal. The input of the phase correction unit is connected to the output of the phase detection unit, and is used to correct the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal. As an optional embodiment of the present invention, the input adjustment module further includes a three-phase and zero-sequence adjustment unit and a zero-sequence synthesis unit, wherein: The zero-sequence synthesis unit includes three parallel symmetrical zero-sequence synthesis circuits. The input terminals of the three zero-sequence synthesis circuits are respectively connected to the A-phase output, B-phase output, and C-phase output acquired by the electronic voltage sensor. The output terminals of the three zero-sequence synthesis circuits are connected together to synthesize the original three-phase voltage signals into the original zero-sequence signal. The three-phase and zero-sequence adjustment unit includes four parallel cascaded signal input conditioning circuits. The four signal input conditioning circuits are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and are used to perform preliminary adjustment on the three-phase voltage signal and the zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal.

[0010] As an optional embodiment of the present invention, the filtering unit is disposed between the signal input conditioning circuit and the three-phase output, and the filtering unit includes a differential input buffer circuit, a Butterworth low-pass filter, and a buffer amplifier circuit, wherein: The input of the differential input buffer circuit is connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and is used to match the output impedance of the electronic voltage sensor with the input impedance of the differential input buffer circuit. The input of the Butterworth low-pass filter is connected to the output of the differential input buffer circuit, and is used to filter out high-order harmonics carried in the original three-phase voltage signal and the original zero-sequence signal. The buffer amplifier circuit is connected to the output of the Butterworth low-pass filter and is used to compensate for the amplitude attenuation of the three-phase signal and the zero-sequence signal during the filtering process.

[0011] As an optional embodiment of the present invention, the three-phase and zero-sequence operational amplifier module includes four parallel cascaded high-voltage operational amplifier circuits. The four high-voltage operational amplifier circuits are connected to four signal input conditioning circuits for power amplification of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal.

[0012] As an optional embodiment of the present invention, the high-voltage operational amplifier circuit adopts a two-stage operational amplifier cascade structure, including a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth operational amplifier, an eleventh resistor, and a thirteenth resistor, wherein.

[0013] The first end of the fifth resistor is connected to the output of the signal input conditioning circuit; the second end of the fifth resistor is connected to the inverting input of the third operational amplifier and the first end of the ninth resistor; the output of the third operational amplifier is connected to the sixth resistor; the second end of the sixth resistor is connected to the inverting input of the fourth operational amplifier, the first end of the seventh resistor, and the first end of the eighth resistor; the second end of the eighth resistor is connected to the output of the fourth operational amplifier, the first end of the tenth resistor, the first end of the eleventh resistor, and the output of the high-voltage operational amplifier circuit; the second end of the tenth resistor is connected to the second end of the eleventh resistor, the second end of the ninth resistor, and the second end of the thirteenth resistor; the second end of the thirteenth resistor, the non-inverting input of the third operational amplifier, the non-inverting input of the fourth operational amplifier, and the second end of the seventh resistor are grounded.

[0014] As an optional embodiment of the present invention, the phase detection unit includes a voltage sampling chip and a phase detection chip, wherein: The sampling input terminal of the voltage sampling chip is connected to the output of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal, and generate a digital sampling voltage signal. The output terminal of the voltage sampling chip is connected to the sampling signal input terminal of the phase detection chip to receive the digital sampling voltage signal. The reference signal input terminal of the voltage sampling chip is connected to the output of the differential input buffer circuit to receive the original three-phase voltage signal and the original zero-sequence signal as a reference signal. The phase detection chip compares the phase difference between the digital sampling voltage signal and the reference signal to output a voltage signal proportional to the phase difference.

[0015] As an optional embodiment of the present invention, the voltage correction unit includes an active phase correction circuit and a microcontroller.

[0016] The input terminal of the microcontroller is connected to the output terminal of the phase detection chip to receive a voltage signal proportional to the phase difference and generate a corresponding phase correction control signal; the output terminal of the microcontroller is connected to the control input terminal of the active phase correction circuit to receive the phase correction control signal; the input terminal of the active phase correction circuit is connected to the output terminal of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal to be corrected; the output terminal of the active phase correction circuit is connected to the output protection module to output the final three-phase voltage signal and the final zero-sequence signal.

[0017] As an optional embodiment of the present invention, the active phase correction circuit includes a voltage-controlled oscillator (VCO). The VCO changes its own oscillation frequency or phase by receiving a phase correction control signal, thereby achieving precise phase shifting of the third three-phase voltage signal and the third zero-sequence signal.

[0018] As an optional embodiment of the present invention, the power supply module includes an input filtering unit, a power factor correction unit, a PWM modulation drive unit, an isolated power conversion unit, and an isolated power supply conversion unit, wherein: The input filtering unit is connected to the AC power grid and is used to rectify the AC mains power into pulsed DC. The power factor correction unit is connected to the input filter unit and is used to convert pulsed DC into high-voltage DC bus. The PWM modulation drive unit is connected to the power factor correction unit and is used to modulate the high-voltage DC bus into a high-frequency pulse square wave signal. The isolated power conversion unit is connected to the PWM modulation drive unit and is used to isolate and convert the high-frequency pulse square wave signal into a secondary high-frequency AC signal. The isolated power supply conversion unit is connected to the secondary output of the isolated power conversion unit and is used to convert the secondary high-frequency AC signal into the low-voltage power supply signal required by the amplifier adapter.

[0019] As an optional embodiment of the present invention, the power supply module further includes an output protection unit, which is located at the isolation feedback terminal between the secondary output of the isolated power conversion unit and the PWM modulation drive unit, and is used to provide isolation feedback for the secondary high-frequency AC signal.

[0020] The signal amplification adapter for power grid upgrading provided in this invention has at least one of the following technical effects: This application provides a signal amplification adapter for power grid upgrading and transformation. By setting a filtering unit including a differential input buffer circuit, a Butterworth low-pass filter and a buffer amplification circuit between the signal input conditioning circuit and the three-phase output, the Butterworth low-pass filter is used to filter out high-order harmonics in the Southeast Asian power grid, thereby improving the working effect of the adapter.

[0021] By setting up a voltage detection unit and a voltage correction unit between the output protection module and the three-phase and zero-sequence operational amplifier module, and by cooperating with the voltage sampling chip and the phase detection chip, accurate detection of phase difference can be achieved; by cooperating with the active phase correction circuit and the microcontroller, the oscillation frequency or phase of the voltage-controlled oscillator can be changed by using the correction control signal to achieve accurate phase shift.

[0022] The zero-sequence synthesis unit synthesizes the A / B / C three-phase signals collected by the electronic voltage sensor into a zero-sequence signal. Then, the signal input conditioning circuit performs primary amplification on the A / B / C three-phase signals and the zero-sequence signal. The high-voltage operational amplifier circuit performs power amplification on the A / B / C three-phase signals and the zero-sequence signal after primary amplification. This achieves precise adaptation of the operating voltage of the electronic voltage sensor and the electromagnetic meter, solves the voltage mismatch problem between new and old equipment, and enables seamless connection without modifying existing equipment, thus improving the compatibility and reusability of power grid equipment.

[0023] By incorporating a power module that includes input filtering, power factor correction, PWM modulation drive, isolated power conversion, isolated power supply conversion, and output protection units, a complete and stable power supply link is formed. Power factor correction improves energy utilization, and isolated power conversion achieves high-voltage isolation, enabling wide-range power supply adaptation and low-power operation. This adapts to the characteristics of large voltage fluctuations in the Southeast Asian power grid, ensuring stable operation of the adapter in low-voltage and voltage drop scenarios, while also improving power supply safety.

[0024] The three-phase voltage signal and zero-sequence signal are initially amplified using four independent parallel cascaded signal input conditioning circuits. These are then precisely amplified using four independent parallel cascaded high-voltage operational amplifier circuits, achieving precise linear amplification. Combined with negative feedback and compensation units in the circuit, low conversion distortion and small phase error of the three-phase voltage signal and zero-sequence signal are ensured, maintaining high-accuracy power metering.

[0025] By using isolated power conversion units, isolated power supply conversion units, and output surge protection, the risk of overvoltage in high-voltage environments is effectively reduced, making it suitable for complex power grid scenarios in Southeast Asia. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the module connection of a signal amplification adapter for power grid upgrading and transformation according to the present invention.

[0028] Figure 2 This is a schematic diagram of a power module for a signal amplification adapter used in power grid upgrades and renovations according to the present invention.

[0029] Figure 3 This is a schematic diagram of an input adjustment module for a signal amplification adapter used in power grid upgrading and transformation according to the present invention.

[0030] Figure 4 This is a schematic diagram of a phase detection and correction module for a signal amplification adapter used in power grid upgrading and transformation according to the present invention.

[0031] Figure 5 This is a zero-sequence synthesis circuit diagram of a signal amplification adapter for power grid upgrading and transformation according to the present invention.

[0032] Figure 6 This is a circuit diagram of a signal input conditioning circuit for a signal amplification adapter used in power grid upgrading and transformation according to the present invention.

[0033] Figure 7 This is a high-voltage operational amplifier circuit diagram of a signal amplification adapter for power grid upgrading and transformation according to the present invention.

[0034] Figure 8 This is a surge protection circuit diagram for a signal amplification adapter used in power grid upgrades and renovations, according to the present invention.

[0035] Figure Descriptions: U1, First Operational Amplifier; R1, First Resistor; R2, Second Resistor; R3, Third Resistor; R4, Fourth Resistor; C1, First Capacitor; C8, Eighth Capacitor; U7, Second Operational Amplifier; R25, Twenty-fifth Resistor; R27, Twenty-seventh Resistor; R37, Thirty-seventh Resistor; R38, Thirty-eighth Resistor; C24, Twenty-fourth Capacitor; C25, Twenty-fifth Capacitor; C18, Eighteenth Capacitor; U3, Third Operational Amplifier; R5, Fifth Resistor; R6, Sixth Resistor; R7, Seventh Resistor; R8, Eighth Resistor; R9, Ninth Resistor; R10, Tenth Resistor; U4, Fourth Operational Amplifier; R11, Eleventh Resistor; R13, Thirteenth Resistor; RV1, First Varistor; D1, First Transient Voltage Suppressor Diode; C46, ​​Forty-sixth Capacitor. Detailed Implementation

[0036] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.

[0037] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of embodiments of the present invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0039] In the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0040] In specific embodiments of the present invention, such as Figure 1 As shown, a signal amplification adapter for power grid upgrading is provided, including a power supply module, a filter module, an input regulation module, a three-phase and zero-sequence operational amplifier module, a phase detection and correction module, and an output protection module, wherein: The power module is used to provide the low-voltage power supply signal required for the amplifier adapter to operate; The input of the input adjustment module is connected to the A-phase output, B-phase output, and C-phase output collected by the electronic voltage sensor. It is used to perform preliminary adjustment on the original three-phase voltage signal and the original zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal. The output of the input adjustment module is connected to the three-phase and zero-sequence operational amplifier module, which is used to amplify the power of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal. The output of the three-phase and zero-sequence operational amplifier module is connected to the input of the phase detection and correction module to correct the phase deviation of the third three-phase voltage signal and the third zero-sequence signal, so as to obtain the final three-phase voltage signal and the final zero-sequence signal. The output protection module is connected to the output of the phase detection and correction module and is used to provide surge protection for the input adjustment module, the three-phase and zero-sequence operational amplifier module and the phase detection and correction module.

[0041] Preferred, refer to Figure 2 The power supply module includes an input filtering unit, a power factor correction unit, a PWM modulation drive unit, an isolated power conversion unit, and an isolated power supply conversion unit, wherein: The input filtering unit is connected to the AC power grid and is used to rectify the AC mains power into pulsed DC. Specifically, the input filtering unit in a specific embodiment of the present invention includes a fuse, a varistor, a common-mode inductor, an ampere capacitor, and a rectifier bridge, wherein: Fuse is used to quickly melt and disconnect the mains power circuit in the event of a short circuit or overload fault, preventing the fault from spreading to subsequent stages and achieving overcurrent protection; Varistor is connected in parallel at the AC input terminal to absorb lightning strikes, instantaneous surges and high voltage spikes in the power grid, and suppress abnormal transient overvoltages; Common mode inductor and ampere capacitor form a common mode rejection circuit to suppress common mode electromagnetic interference in the AC line, filter out high-frequency noise, and purify the input power quality; Rectifier bridge is used to convert the power frequency AC voltage into unidirectional pulsating pulsed DC, thereby providing a basic DC input source for subsequent circuits.

[0042] The power factor correction unit is connected to the input filter unit and is used to convert pulsed DC into high-voltage DC bus. Specifically, the power factor correction unit in a specific embodiment of the present invention includes an FPC main switch, a driving transistor, a current-limiting bias resistor, a filter capacitor, a fast recovery boost diode, a high-voltage energy storage capacitor, and a clamping absorption circuit, wherein: A driving transistor, in conjunction with surrounding resistors and capacitors, amplifies the control signal to drive the PFC main switch to turn on and off at high frequency. A fast recovery diode, together with the FPC main switch, forms a Boost converter topology, completing energy freewheeling and voltage boosting during the FPC main switch's turn-off phase. High-voltage electrolytic capacitors are connected in parallel to store energy and smooth the boosted voltage, normalizing the pulsating DC input into a stable high-voltage DC bus. A clamping absorption circuit suppresses voltage spikes and oscillations generated by the high-frequency switching of the FPC main switch, preventing device breakdown. This unit, through an active boost correction structure, corrects the input current waveform while stabilizing the high-voltage bus output, improving the power factor, reducing grid harmonic pollution, and achieving a normalized conversion from pulsating DC to a stable high-voltage DC bus.

[0043] The PWM modulation drive unit is connected to the power factor correction unit and is used to modulate the high-voltage DC bus into a high-frequency pulse square wave signal. Specifically, the PWM modulation drive unit in a specific embodiment of the present invention includes a PWM control chip, a power switch, a loop compensation network, a voltage divider sampling resistor, and a Zener diode, wherein: The PWM main control chip has built-in oscillation and modulation logic, and outputs high-frequency drive control signals; the power switch receives the drive signal and switches on and off at high speed, chopping and modulating the continuous high-voltage DC bus into a high-frequency pulse square wave, providing a basis for isolated energy transmission; the voltage divider sampling resistor collects the output voltage signal from the back end, and forms a closed-loop regulation with the loop compensation network to prevent circuit oscillation and improve system stability; the Zener diode and surrounding RC components realize signal clamping and filtering, protecting the control chip from pulse spike interference, and reliably completing the modulation output from high-voltage DC to high-frequency pulse square wave.

[0044] The isolated power conversion unit is connected to the PWM modulation drive unit and is used to isolate and convert the high-frequency pulse square wave signal into a secondary high-frequency AC signal. Specifically, the isolated power conversion unit in a specific embodiment of the present invention includes a high-frequency isolation transformer and multiple high-voltage rectifier diodes, wherein: The high-frequency isolation transformer is the core isolation conversion device. It relies on electromagnetic coupling to achieve complete electrical isolation between the high-voltage side of the primary mains power supply and the low-voltage side of the signal secondary side, preventing high-voltage interference into the downstream signal conditioning circuit and meeting the safety isolation requirements of power equipment. Simultaneously, through different turns ratios in the primary and secondary windings, it couples and converts the high-frequency pulse square wave energy of the primary side into multiple high-frequency AC signals of different voltage levels on the secondary side. Utilizing the transformer's magneto-electric isolation transmission characteristics, it completes the cross-side conversion of energy and signal under safe isolation, stably outputting multiple high-frequency AC signals on the secondary side, realizing the conversion function of high-voltage high-frequency pulses to isolated secondary AC signals. Multiple high-voltage rectifier diodes correspond to different secondary windings of the transformer, unidirectionally rectifying the multiple high-frequency AC signals on the secondary side into DC voltage.

[0045] The isolated power supply conversion unit is connected to the secondary output of the isolated power conversion unit and is used to convert the secondary high-frequency AC signal into the DC power supply signal required by the amplifier adapter.

[0046] Specifically, the isolated power supply conversion unit in a specific embodiment of the present invention includes a high-voltage filter capacitor, a low-voltage side common-mode inductor, and a low-voltage filter capacitor, wherein: The high-voltage filter capacitor stores and smooths the DC power supply signal output from the secondary side of the high-frequency isolation transformer, providing a clean high-voltage operating power supply for the three-phase and zero-sequence high-voltage operational amplifier circuits. In a specific embodiment of this invention, the output is ±200V high-voltage DC. The low-voltage side common-mode inductor, together with multiple sets of low-voltage filter capacitors, forms a multi-stage EMC filter network to suppress ripple and purify noise in the low-voltage control power supply. Through the combined design of rectification, multi-stage filtering, and impedance optimization, the ±200V high-voltage power supply and ±15V low-voltage isolation power supply are stably output, fully meeting the differentiated power supply requirements of the amplifier adapter operational amplifier control and the entire high-voltage amplification module.

[0047] Specifically, the power module adopts a two-stage architecture: a power factor correction unit for boost correction and a PWM modulation drive unit for closed-loop regulation. The power factor correction unit, over a wide AC input range, uniformly boosts and stabilizes rectified pulsating DC of varying amplitudes into a constant high-voltage bus. The subsequent PWM and isolation power conversion unit then performs closed-loop regulation and isolation conversion on the high-frequency pulse signal, enabling the module to stably output high-voltage DC over a wide AC input voltage range. The power module in this specific embodiment supports an ultra-wide AC input range of 30V–240V, and can operate stably even under low-voltage grid conditions, voltage dips, or temporary generator power supply scenarios, significantly outperforming conventional adapters (typically limited to 100–240V).

[0048] Preferred, refer to Figure 2 The power module also includes an output protection unit, which is located at the isolation feedback terminal between the secondary output of the isolated power conversion unit and the PWM modulation drive unit, and is used to isolate and provide feedback on the secondary high-frequency AC signal.

[0049] Specifically, the output protection unit includes an optocoupler, a Zener clamping transistor, a current-limiting resistor, and a filter capacitor, wherein; The optocoupler, as the core device for isolation feedback, achieves electrical isolation between the secondary power supply circuit and the primary PWM modulation drive unit, isolating and transmitting the secondary output voltage and abnormal load signals to the primary PWM main control chip, forming a closed-loop voltage regulation across the isolation layer. The Zener diode is connected in parallel to the high-voltage output circuit to accurately clamp the high-voltage power supply amplitude, preventing output overvoltage from damaging the subsequent high-voltage operational amplifier and signal conditioning devices. The current-limiting resistor limits the operating current of the clamping circuit, protecting the voltage regulator devices from stable operation. The filter capacitor filters out high-frequency interference in the feedback circuit, ensuring accurate sampling and stable transmission of the feedback signal. This unit monitors the secondary power supply status in real time, corrects the modulation parameters of the front-end modulation drive unit in real time through isolation feedback, and simultaneously achieves high-voltage output overvoltage clamping protection, comprehensively improving the load stability and fault protection capability of the power module.

[0050] Preferred, refer to Figure 3 The input regulation module includes a three-phase and zero-sequence regulation unit, a zero-sequence synthesis unit, and a filtering unit, wherein: The zero-sequence synthesis unit includes three parallel symmetrical zero-sequence synthesis circuits. The input terminals of the three zero-sequence synthesis circuits are respectively connected to the A-phase output, B-phase output, and C-phase output acquired by the electronic voltage sensor. The output terminals of the three zero-sequence synthesis circuits are connected together to synthesize the original three-phase voltage signals into the original zero-sequence signal. The three-phase and zero-sequence adjustment unit includes four parallel cascaded signal input conditioning circuits. The four signal input conditioning circuits are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and are used to perform preliminary adjustment on the three-phase voltage signal and the zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal.

[0051] The input adjustment module includes four parallel cascaded filtering units, which are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal to filter out high-order harmonic interference.

[0052] Specifically, refer to Figure 5 The zero-sequence synthesis circuit includes a first operational amplifier U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, and an eighth capacitor C8, wherein: The first end of the second resistor R2 is connected to the A-phase output; the second end of the second resistor R2 is connected to the non-inverting input of the first operational amplifier U1; the first end of the first resistor R1 is connected to the inverting input of the first operational amplifier U1; the second end of the second resistor R2 is connected to the output of the first operational amplifier U1, the first end of the third resistor R3, and the first end of the fourth resistor R4; the second end of the third resistor R3 is connected to the output of the zero-sequence synthesis circuit; the first end of the first capacitor C1 is connected to the positive power input of the first operational amplifier U1; the first end of the eighth capacitor C8 is connected to the negative power input of the first operational amplifier U1; the second ends of the first capacitor C1, the second ends of the eighth capacitor C8, and the second end of the fourth resistor R4 are grounded.

[0053] Specifically, refer to Figure 6 The signal input conditioning circuit includes a second operational amplifier U7, a resistor feedback network, a twenty-fifth resistor R25, a twenty-seventh resistor R27, a thirty-seventh resistor R37, a thirty-eighth resistor R38, a twenty-fourth capacitor C24, a twenty-fifth capacitor C25, and an eighteenth capacitor C18, wherein: The first terminal of the 25th resistor R25 is connected to the A-phase output; the second terminal of the 25th resistor R25 is connected to the inverting input terminal of the second operational amplifier U7, the first terminal of the 18th capacitor C18, the first terminal of the 35th resistor R35, and the first terminal of the resistor feedback network; the second terminal of the resistor feedback network is connected to the second terminal of the 18th capacitor C18, the second terminal of the 35th resistor R35, the first terminal of the 27th resistor R27, the first terminal of the 38th resistor R38, and the output terminal of the second operational amplifier U7; the second terminal of the 27th resistor R27 is connected to the input terminal of the high-voltage operational amplifier circuit; the first terminal of the 37th resistor R37 is connected to the non-inverting input terminal of the second operational amplifier U7; the first terminal of the 24th capacitor C24 is connected to the positive power input terminal of the second operational amplifier U7; the first terminal of the 25th capacitor C25 is connected to the negative power input terminal of the second operational amplifier U7; the second terminals of the 24th capacitor C24, the 25th capacitor C25, the 37th resistor R37, and the 38th resistor R38 are grounded.

[0054] Preferred, refer to Figure 6 The resistor feedback network includes at least two parallel feedback resistors, which are connected in parallel between the 25th resistor R25 and the 27th resistor R27.

[0055] In a specific embodiment of the present invention, the resistive feedback network uses eight parallel feedback resistors, namely the twenty-sixth resistor R26, the twenty-eighth resistor R28, the twenty-ninth resistor R29, the thirtieth resistor R30, the thirty-first resistor R31, the thirty-second resistor R32, and the thirty-third resistor R33.

[0056] Specifically, the filtering unit is disposed between the signal input conditioning circuit and the three-phase output. The filtering unit includes a differential input buffer circuit, a Butterworth low-pass filter, and a buffer amplifier circuit, wherein: The input of the differential input buffer circuit is connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and is used to match the output impedance of the electronic voltage sensor with the input impedance of the differential input buffer circuit. The input of the Butterworth low-pass filter is connected to the output of the differential input buffer circuit, and is used to filter out high-order harmonics carried in the original three-phase voltage signal and the original zero-sequence signal. The buffer amplifier circuit is connected to the output of the Butterworth low-pass filter and is used to compensate for the amplitude attenuation of the three-phase signal and the zero-sequence signal during the filtering process.

[0057] In a specific embodiment of the present invention, the differential input buffer circuit preferably uses a high-precision instrumentation operational amplifier AD8421 as the core component. The non-inverting input terminal of the operational amplifier is connected to the output terminal of the signal input conditioning circuit, and the inverting input terminal is grounded through a matching resistor. The power supply terminal of the operational amplifier adopts ±15V low-voltage isolation power supply. A ceramic capacitor and an electrolytic capacitor are connected in parallel at the power supply terminal to form a decoupling network to filter out the interference of power supply ripple on the buffer circuit and ensure the stability of the buffer output signal. The Butterworth low-pass filter is a 4th-order or 5th-order Butterworth low-pass filter with a cutoff frequency set to 500Hz. It can effectively filter out the 5th and higher harmonics in the power grid (mainly harmonic signals of 300Hz and above), while preserving the amplitude and phase of the fundamental signal to the maximum extent. The buffer amplifier circuit preferably uses a non-inverting amplification structure, and the amplification gain of the operational amplifier is set to 1.2 times, which just compensates for the amplitude attenuation caused by the Butterworth low-pass filter and ensures that the amplitude of the filtered signal is consistent with that before filtering.

[0058] Preferred, refer to Figure 7 The three-phase and zero-sequence operational amplifier module includes four parallel cascaded high-voltage operational amplifier circuits. The four high-voltage operational amplifier circuits are connected to four signal input conditioning circuits to amplify the power of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal.

[0059] Specifically, refer to Figure 7 The high-voltage operational amplifier circuit adopts a two-stage cascaded operational amplifier structure, including a third operational amplifier U3, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a fourth operational amplifier U4, an eleventh resistor R11, and a thirteenth resistor R13, wherein: The first end of the fifth resistor R5 is connected to the output of the signal input conditioning circuit; the second end of the fifth resistor R5 is connected to the inverting input of the third operational amplifier U3 and the first end of the ninth resistor R9; the output of the third operational amplifier U3 is connected to the sixth resistor R6; the second end of the sixth resistor R6 is connected to the inverting input of the fourth operational amplifier U4, the first end of the seventh resistor R7, and the first end of the eighth resistor R8; the second end of the eighth resistor R8 is connected to the output of the fourth operational amplifier U4, the first end of the tenth resistor R10, the first end of the eleventh resistor R11, and the output of the high-voltage operational amplifier circuit; the second end of the tenth resistor R10 is connected to the second end of the eleventh resistor R11, the second end of the ninth resistor R9, and the second end of the thirteenth resistor R13; the second end of the thirteenth resistor R13, the positive input of the third operational amplifier U3, the positive input of the fourth operational amplifier U4, and the second end of the seventh resistor R7 are grounded.

[0060] In a specific embodiment of the present invention, the resistance values ​​of the fifth resistor R5, sixth resistor R6, seventh resistor R7, eighth resistor R8, ninth resistor R9, tenth resistor R10, eleventh resistor R11, and thirteenth resistor R13 in the high-voltage operational amplifier circuit are not absolute, but it is necessary to ensure that the amplification gain of the third operational amplifier U3 and the fourth operational amplifier U4 is close to 30 times. This is to ensure that the output voltage of the electronic voltage sensor (1.875V) is compatible with the voltage of the electromagnetic meter (57.735V). The present invention provides a preferred set of resistor settings: the resistance value of the fifth resistor R5 is preferably 47KΩ, the resistance value of the sixth resistor R6 is preferably 10KΩ, the resistance value of the seventh resistor R7 is preferably 6.8KΩ, the resistance value of the eighth resistor R8 is preferably 3.3MΩ, the resistance value of the ninth resistor R9 is preferably 47KΩ, the resistance value of the tenth resistor R10 is preferably 220KΩ, the resistance value of the eleventh resistor R11 is preferably 4.32MΩ, and the resistance value of the thirteenth resistor R13 is preferably 6.8KΩ.

[0061] In a specific embodiment of the present invention, the gain of a preferred resistor setting scheme is calculated, and the calculation process is as follows: The amplification gain of the third operational amplifier U3 depends on the ratio of the resistance of the fifth resistor R5 (input resistor) to the resistance of the ninth resistor R9 (feedback resistor). Since the resistance of both the fifth resistor R5 and the ninth resistor R9 is 47KΩ, the amplification gain of the third operational amplifier U3 (inverting) is -1.

[0062] The amplification gain of the fourth operational amplifier U4 depends on the ratio of the resistance of the seventh resistor R7 (input resistor) to the parallel connection of the tenth resistor R10 and the eleventh resistor R11 (feedback resistor). Since the resistance of the tenth resistor R10 is preferably 220KΩ, the resistance of the eleventh resistor R11 is preferably 4.32MΩ, the resistance of the seventh resistor R7 is preferably 6.8KΩ, and the resistance of the eleventh resistor R11 and the tenth resistor R10 in parallel is 209.339KΩ; therefore, the amplification gain of the fourth operational amplifier U4 (inverting) is -30.78518.

[0063] Therefore, the overall gain of the high-voltage operational amplifier circuit is the product of the amplification gain of the third operational amplifier U3 and the amplification gain of the fourth operational amplifier U4, preferably 30.78518. This gain is sufficient to amplify the output voltage of the electronic voltage sensor to match the operating voltage of the electromagnetic meter.

[0064] Preferred, refer to Figure 4 The phase detection and correction module includes a phase detection unit and a phase correction unit. The input of the phase detection unit is connected to the output of the three-phase and zero-sequence operational amplifier module, and is used to detect the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal. The input of the phase correction unit is connected to the output of the phase detection unit, and is used to correct the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal.

[0065] Specifically, the phase detection unit includes a voltage sampling chip and a phase detection chip, wherein: The sampling input terminal of the voltage sampling chip is connected to the output of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal, and generate a digital sampling voltage signal. The output terminal of the voltage sampling chip is connected to the sampling signal input terminal of the phase detection chip to receive the digital sampling voltage signal. The reference signal input terminal of the voltage sampling chip is connected to the output of the differential input buffer circuit to receive the original three-phase voltage signal and the original zero-sequence signal as a reference signal. The phase detection chip compares the phase difference between the digital sampling voltage signal and the reference signal to output a voltage signal proportional to the phase difference.

[0066] In a specific embodiment of the present invention, the voltage sampling chip is preferably an ADS1256. The sampling input terminal of the voltage sampling chip divides the amplified signal through a voltage divider resistor to ensure that the input signal amplitude is within the chip's allowable range. The reference signal input terminal is directly connected to the output terminal of the differential input buffer circuit to collect the original signal as a reference. The digital interface (SPI) is connected to the phase detection chip to transmit the converted digital sampled voltage signal to the phase detection chip in real time. The phase detection chip is preferably a CD4046 phase-locked loop chip, which integrates a phase comparator, a voltage-controlled oscillator, and other modules to achieve high-precision phase detection with a detection accuracy of up to 0.1°. The sampling signal input terminal (IN1) of the phase detection chip is connected to the digital output terminal of the ADS1256, and the reference signal input terminal (IN2) is synchronously connected to the reference signal input terminal of the voltage sampling chip and the output terminal of the differential input buffer circuit. The phase difference between the two signals is compared by the phase comparator, and the output terminal (OUT) outputs an analog voltage signal proportional to the phase difference, providing a precise control signal for subsequent phase correction.

[0067] Specifically, the voltage correction unit includes an active phase correction circuit and a microcontroller.

[0068] The input terminal of the microcontroller is connected to the output terminal of the phase detection chip to receive a voltage signal proportional to the phase difference and generate a corresponding phase correction control signal; the output terminal of the microcontroller is connected to the control input terminal of the active phase correction circuit to receive the phase correction control signal; the input terminal of the active phase correction circuit is connected to the output terminal of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal to be corrected; the output terminal of the active phase correction circuit is connected to the output protection module to output the final three-phase voltage signal and the final zero-sequence signal.

[0069] In a specific embodiment of the present invention, the microcontroller is preferably an STM32 series chip. The analog input port (ADC1) of the microcontroller is connected to the output of the phase detection chip, receiving an analog voltage signal proportional to the phase difference. The built-in ADC module converts the analog signal into a digital signal, calculates the specific phase deviation value using an internal algorithm, and then generates a corresponding phase correction control signal based on the phase deviation value. This signal is transmitted to the active phase correction circuit through the digital output port (GPIO). The active phase correction circuit includes a voltage-controlled oscillator (VCO). The VCO changes its oscillation frequency or phase by receiving the phase correction control signal, thereby achieving precise phase shifting of the third three-phase voltage signal and the third zero-sequence signal.

[0070] Specifically, the microcontroller has a preset phase deviation threshold. When the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal exceeds the preset threshold, the microcontroller will issue the corresponding phase correction control signal. Otherwise, the active phase correction circuit will output the third three-phase voltage signal and the third zero-sequence signal as the final three-phase voltage signal and the final zero-sequence signal.

[0071] Preferred, refer to Figure 8 The output protection module includes four cascaded surge protection circuits. Each surge protection circuit includes a first varistor RV1, a first transient suppression diode D1, and a forty-sixth capacitor C46, ​​wherein: The first terminal of the forty-sixth capacitor C46 is connected to the first terminal of the first transient suppression diode D1, the first terminal of the first varistor RV1, and the output terminal of the high-voltage operational amplifier circuit; the second terminal of the forty-sixth capacitor C46, ​​the second terminal of the first transient suppression diode D1, and the second terminal of the first varistor RV1 are grounded.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A signal amplification adapter for grid modernization, characterized by, It includes a power supply module, a filter module, an input regulation module, a three-phase and zero-sequence operational amplifier module, a phase detection and correction module, and an output protection module, wherein: The power module is used to provide the low-voltage power supply signal required for the amplifier adapter to operate; The input of the input adjustment module is connected to the A-phase output, B-phase output, and C-phase output collected by the electronic voltage sensor. It is used to perform preliminary adjustment on the original three-phase voltage signal and the original zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal. The output of the input adjustment module is connected to the three-phase and zero-sequence operational amplifier module, which is used to amplify the power of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal. The output of the three-phase and zero-sequence operational amplifier module is connected to the input of the phase detection and correction module to correct the phase deviation of the third three-phase voltage signal and the third zero-sequence signal, so as to obtain the final three-phase voltage signal and the final zero-sequence signal. The output protection module is connected to the output of the phase detection and correction module, and is used to provide surge protection for the input adjustment module, the three-phase and zero-sequence operational amplifier module and the phase detection and correction module. The input adjustment module includes four parallel cascaded filtering units, which are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal to filter out high-order harmonic interference. The phase detection and correction module includes a phase detection unit and a phase correction unit. The input of the phase detection unit is connected to the output of the three-phase and zero-sequence operational amplifier module, and is used to detect the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal. The input of the phase correction unit is connected to the output of the phase detection unit, and is used to correct the phase difference between the third three-phase voltage signal and the third zero-sequence signal and the original three-phase voltage signal and the original zero-sequence signal.

2. A signal amplification adapter for grid modernization according to claim 1, characterized in that, The input regulation module further includes a three-phase and zero-sequence regulation unit and a zero-sequence synthesis unit, wherein: The zero-sequence synthesis unit includes three parallel symmetrical zero-sequence synthesis circuits. The input terminals of the three zero-sequence synthesis circuits are respectively connected to the A-phase output, B-phase output, and C-phase output acquired by the electronic voltage sensor. The output terminals of the three zero-sequence synthesis circuits are connected together to synthesize the original three-phase voltage signals into the original zero-sequence signal. The three-phase and zero-sequence adjustment unit includes four parallel cascaded signal input conditioning circuits. The four signal input conditioning circuits are respectively connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and are used to perform preliminary adjustment on the three-phase voltage signal and the zero-sequence signal to obtain the second three-phase voltage signal and the second zero-sequence signal.

3. A signal amplification adapter for grid modernization according to claim 2, characterized in that, The filtering unit is disposed between the signal input conditioning circuit and the three-phase output. The filtering unit includes a differential input buffer circuit, a Butterworth low-pass filter, and a buffer amplifier circuit, wherein: The input of the differential input buffer circuit is connected to the A-phase output, B-phase output, C-phase output, and zero-sequence signal, and is used to match the output impedance of the electronic voltage sensor with the input impedance of the differential input buffer circuit. The input of the Butterworth low-pass filter is connected to the output of the differential input buffer circuit, and is used to filter out high-order harmonics carried in the original three-phase voltage signal and the original zero-sequence signal. The buffer amplifier circuit is connected to the output of the Butterworth low-pass filter and is used to compensate for the amplitude attenuation of the three-phase signal and the zero-sequence signal during the filtering process.

4. A signal amplification adapter for power grid upgrading and transformation according to claim 1, characterized in that, The three-phase and zero-sequence operational amplifier module includes four parallel cascaded high-voltage operational amplifier circuits. The four high-voltage operational amplifier circuits are connected to four signal input conditioning circuits to amplify the power of the second three-phase voltage signal and the second zero-sequence signal to obtain the third three-phase voltage signal and the third zero-sequence signal.

5. A signal amplification adapter for power grid upgrading and transformation according to claim 4, characterized in that, The high-voltage operational amplifier circuit adopts a two-stage operational amplifier cascade structure, including a third operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, a fourth operational amplifier, an eleventh resistor, and a thirteenth resistor. The first end of the fifth resistor is connected to the output of the signal input conditioning circuit; the second end of the fifth resistor is connected to the inverting input of the third operational amplifier and the first end of the ninth resistor; the output of the third operational amplifier is connected to the sixth resistor; the second end of the sixth resistor is connected to the inverting input of the fourth operational amplifier, the first end of the seventh resistor, and the first end of the eighth resistor; the second end of the eighth resistor is connected to the output of the fourth operational amplifier, the first end of the tenth resistor, the first end of the eleventh resistor, and the output of the high-voltage operational amplifier circuit; the second end of the tenth resistor is connected to the second end of the eleventh resistor, the second end of the ninth resistor, and the second end of the thirteenth resistor; the second end of the thirteenth resistor, the non-inverting input of the third operational amplifier, the non-inverting input of the fourth operational amplifier, and the second end of the seventh resistor are grounded.

6. A signal amplification adapter for power grid upgrading and transformation according to claim 3, characterized in that, The phase detection unit includes a voltage sampling chip and a phase detection chip, wherein: The sampling input terminal of the voltage sampling chip is connected to the output of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal, and generate a digital sampling voltage signal. The output terminal of the voltage sampling chip is connected to the sampling signal input terminal of the phase detection chip to receive the digital sampling voltage signal. The reference signal input terminal of the voltage sampling chip is connected to the output of the differential input buffer circuit to receive the original three-phase voltage signal and the original zero-sequence signal as a reference signal. The phase detection chip compares the phase difference between the digital sampling voltage signal and the reference signal to output a voltage signal proportional to the phase difference.

7. A signal amplification adapter for grid modernization according to claim 6, characterized in that, The voltage correction unit includes an active phase correction circuit and a microcontroller. The input terminal of the microcontroller is connected to the output terminal of the phase detection chip to receive a voltage signal proportional to the phase difference and generate a corresponding phase correction control signal; the output terminal of the microcontroller is connected to the control input terminal of the active phase correction circuit to receive the phase correction control signal; the input terminal of the active phase correction circuit is connected to the output terminal of the three-phase and zero-sequence operational amplifier module to receive the third three-phase voltage signal and the third zero-sequence signal to be corrected; the output terminal of the active phase correction circuit is connected to the output protection module to output the final three-phase voltage signal and the final zero-sequence signal.

8. A signal amplification adapter for grid modernization according to claim 6, characterized in that, The active phase correction circuit includes a voltage-controlled oscillator (VCO). The VCO changes its oscillation frequency or phase by receiving a phase correction control signal, thereby achieving precise phase shifting of the third three-phase voltage signal and the third zero-sequence signal.

9. The signal amplification adapter for grid modernization of claim 1, wherein, The power supply module includes an input filtering unit, a power factor correction unit, a PWM modulation drive unit, an isolated power conversion unit, and an isolated power supply conversion unit, wherein: The input filtering unit is connected to the AC power grid and is used to rectify the AC mains power into pulsed DC. The power factor correction unit is connected to the input filter unit and is used to convert pulsed DC into high-voltage DC bus. The PWM modulation drive unit is connected to the power factor correction unit and is used to modulate the high-voltage DC bus into a high-frequency pulse square wave signal. The isolated power conversion unit is connected to the PWM modulation drive unit and is used to isolate and convert the high-frequency pulse square wave signal into a secondary high-frequency AC signal. The isolated power supply conversion unit is connected to the secondary output of the isolated power conversion unit and is used to convert the secondary high-frequency AC signal into the low-voltage power supply signal required by the amplifier adapter.

10. A signal amplification adapter for grid modernization according to claim 9, characterized in that, The power module also includes an output protection unit, which is located at the isolation feedback terminal between the secondary output of the isolated power conversion unit and the PWM modulation drive unit, and is used to isolate and provide feedback on the secondary high-frequency AC signal.

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