Current power amplifier circuit and smart substation debugging device

Abstract

The utility model belongs to the technical field of intelligent substation, provide a kind of current power amplifier circuit and intelligent substation debugging equipment. On the one hand, the utility model uses the power amplifier circuit of closed loop structure, output part uses the closed loop structure of " operational amplifier+ sampling resistance+ differential amplifier chip+ power MOS tube", so that current output has good linearity and stability, is suitable as protection device test, secondary circuit injection flow occasion. On the other hand, the utility model is by setting isolated industrial computer power supply circuit, the current power amplifier circuit of closed loop structure, two-stage voltage power amplifier circuit of conditioning, etc., constructs more stable, stronger anti-interference ability, higher precision of acquisition and output hardware structure system, to meet the requirement of intelligent substation field multi-scene debugging.

Description

Technical Field

[0001] This utility model belongs to the field of intelligent substation technology, and in particular relates to a current power amplifier circuit and intelligent substation debugging equipment. Background Technology

[0002] With the development of smart substation technology, smart substation commissioning equipment needs to simultaneously undertake multiple testing tasks, including analog output, analog acquisition, digital input / output, and network communication. While traditional commissioning equipment can meet basic functional requirements, its hardware structure often employs a relatively simple modular combination approach.

[0003] In particular, the power amplifier section uses an open-loop power amplifier method, resulting in limited output stability and linearity. Moreover, the acquisition circuits mostly use voltage dividers or single operational amplifiers for conditioning, leading to insufficient anti-interference capability and range matching.

[0004] Furthermore, because the power supply circuits of industrial control computers or main control systems often employ single-stage isolation DC-DC conversion and basic filtering structures, the filtering measures at the input and output ends are relatively simple and cannot adequately suppress ripple, surges, and electromagnetic interference from 24V industrial power supplies. This can easily cause power supply noise to couple into the data processing, communication, and control circuits of the main control board, thereby affecting the overall operational stability. Traditional switching circuits often use single-stage optocouplers or single relay drives, which have limited isolation and protection capabilities between the input / output and the main control, limiting reliability in high-interference environments. While these structures can operate in conventional commissioning scenarios, they exhibit certain limitations in the environment of intelligent substations, which are characterized by strong interference, high precision requirements, and complex interface types. Utility Model Content

[0005] In view of the above problems, the purpose of this utility model is to provide a power amplifier circuit and intelligent substation debugging equipment, which aims to solve the above technical problems.

[0006] The present invention adopts the following technical solution:

[0007] On one hand, the current power amplifier circuit includes a first buffer circuit, a first-stage amplifier circuit, a second-stage amplifier circuit, a reference voltage divider circuit, an isolation drive circuit, and a sampling resistor RW connected in sequence. One end of the sampling resistor RW serves as the output, and the input signal is input to the first buffer circuit. The power amplifier circuit also includes a differential amplifier circuit. The two ends of the sampling resistor RW are respectively connected to the differential amplifier circuit as inputs. The output of the differential amplifier circuit is connected to the second-stage amplifier circuit. The output of the differential amplifier circuit is also connected in sequence to a second buffer circuit, a comparator circuit, and an optocoupler output isolation circuit.

[0008] Furthermore, the first buffer circuit includes operational amplifier U1A, the output terminal of which is connected to the negative input terminal. The input signal is connected to the positive input terminal of operational amplifier U1A through resistor R11, and the positive input terminal is connected to ground through resistor R12. The first-stage amplifier circuit includes operational amplifier U1B, the output terminal of operational amplifier U1A is connected to the negative input terminal of operational amplifier U1B through resistor R21, and a capacitor C21 and a resistor R22 are connected in parallel between the negative input terminal and the output terminal of operational amplifier U1B. The positive input terminal of operational amplifier U1B is connected to ground through resistor R24, and the output terminal of operational amplifier U1B is connected to resistor R23.

[0009] Furthermore, the secondary amplifier circuit includes operational amplifier U2A. A resistor R31 and a capacitor C31 are connected between the negative input terminal and the output terminal of operational amplifier U2A. The negative input terminal of operational amplifier U2A is connected to ground through resistor R32. The output terminal of operational amplifier U1B is connected to the negative input terminal of operational amplifier U2A through resistor R23. The reference voltage divider circuit includes a precision reference source chip Q. The output terminal of operational amplifier U2A is connected to the operating power supply sequentially through three voltage divider resistors R41, R42, and R43. The anode and cathode of the precision reference source chip Q are connected to the non-connected voltage divider resistors R41 and R42. At both ends, the reference reference terminal of the precision reference source chip Q is connected to the junction of voltage divider resistors R41 and R42. A capacitor C41 is also connected between the anode and cathode of the precision reference source chip Q. The isolation drive circuit includes a MOSFET. A diode D1 is connected between the source and drain of the MOSFET. The drain of the MOSFET is connected to the bus power supply. The output terminal of the operational amplifier U2A is connected to the source of the MOSFET through a resistor R52. A resistor R53 is also connected between the source and gate of the MOSFET. The cathode of the precision reference source chip Q is also connected to the gate of the MOSFET through a resistor R51.

[0010] Furthermore, the differential amplifier circuit includes a differential amplifier chip U5, with the two ends of the sampling resistor RW connected to the differential input terminal of the differential amplifier chip U5, the output terminal of the differential amplifier chip U5 connected to the second buffer circuit, and the output terminal of the differential amplifier chip U5 connected to the second stage amplifier circuit through a capacitor C51 and a resistor R51 in parallel.

[0011] Furthermore, the second buffer circuit includes operational amplifier U2B, the output of which is connected to the negative input terminal. The comparator circuit includes operational amplifier U4A, the positive input terminal of which is connected to ground via resistor R81 and to the operating power supply via resistor R82. The optocoupler output isolation circuit includes operational amplifier U4B and optocoupler U3. The output of operational amplifier U4A is connected to the operating power supply via pull-up resistor R91 and to the positive input terminal of operational amplifier U4B via resistor R92. The positive input terminal of operational amplifier U4B is connected to ground via capacitor C7. The negative input terminal of operational amplifier U4B is connected to ground via resistor R95 and to the operating power supply via resistor R93. The output of operational amplifier U4B is connected to one input terminal of optocoupler U3, and the other input terminal of optocoupler U3 is connected to the operating power supply via resistor R94.

[0012] On the other hand, the debugging equipment includes a main control board, which is connected to a power supply circuit, a digital input / output circuit, and a DAC circuit. The DAC circuit is connected to a current amplifier circuit and a voltage amplifier circuit. The voltage amplifier circuit has a voltage output, and the current amplifier circuit has a current output.

[0013] Furthermore, the power supply circuit includes a first common-mode inductor, a first filter network, an isolated DC-DC converter module, a second filter network, a second common-mode inductor, and a third filter network connected in sequence, with the third filter network outputting the operating power supply.

[0014] Furthermore, the voltage power amplifier circuit adopts a two-stage amplification structure consisting of a pre-stage operational amplifier and a post-stage operational amplifier.

[0015] The beneficial effects of this utility model are:

[0016] On one hand, this utility model adopts a closed-loop power amplifier circuit. The output section uses a closed-loop structure of "operational amplifier + sampling resistor + differential amplifier chip + power MOSFET": the pre-stage operational amplifier amplifies and filters the control signal, and the output drives the power MOSFET; the output branch is connected in series with a precision sampling resistor, and the sampled voltage is amplified by the differential amplifier and sent back to the pre-stage operational amplifier as a feedback signal to realize closed-loop control of the output current; at the same time, an overcurrent detection and isolation alarm circuit is formed by using an LM393 comparator and optocouplers. When the output current exceeds the set threshold, the comparator flips and sends a protection signal to the main control board through the optocoupler, thus forming a current power amplifier structure that can output accurately and has protection function.

[0017] On the other hand, this utility model also provides an intelligent substation commissioning device, which adopts a two-stage amplification circuit structure and an isolated industrial control computer power supply circuit, achieving significant improvements in power supply stability, output accuracy, and overall anti-interference capability, making it more suitable for long-term stable applications in intelligent substations, power protection system commissioning, and industrial measurement and control. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the power amplifier circuit provided by this utility model.

[0019] Figure 2 This is a circuit diagram of the power amplifier circuit provided by this utility model.

[0020] Figure 3 This is a circuit diagram of the first buffer circuit and the first-stage amplifier circuit provided by this utility model.

[0021] Figure 4 This is a circuit diagram of the two-stage amplifier circuit, the reference voltage divider circuit, and the isolation drive circuit provided by this utility model.

[0022] Figure 5 This is a circuit diagram of the differential amplifier circuit provided by this utility model.

[0023] Figure 6 This is a circuit diagram of the second buffer circuit, the comparator circuit, and the optocoupler output isolation circuit provided by this utility model.

[0024] Figure 7 This is a schematic diagram of the intelligent substation commissioning equipment provided by this utility model.

[0025] Figure 8 This is a schematic diagram of the power supply circuit provided by this utility model.

[0026] Figure 9 This is a circuit diagram of the voltage power amplifier circuit provided by this utility model. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this utility model patent clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.

[0028] To illustrate the technical solution described in this utility model, specific embodiments are described below.

[0029] For ease of explanation, only the parts relevant to the embodiments of this utility model are shown.

[0030] Combination Figure 1-2As shown, this embodiment provides a current power amplifier circuit, including a first buffer circuit 1, a first-stage amplifier circuit 2, a second-stage amplifier circuit 3, a reference voltage divider circuit 4, an isolation drive circuit 5, and a sampling resistor RW connected in sequence. One end of the sampling resistor RW serves as the output, and the input signal is input to the first buffer circuit 1. The power amplifier circuit also includes a differential amplifier circuit 6. The two ends of the sampling resistor RW are respectively connected to the differential amplifier circuit 6 as inputs. The output of the differential amplifier circuit 6 is connected to the second-stage amplifier circuit 3. The output of the differential amplifier circuit 6 is also sequentially connected to a second buffer circuit 7, a comparator circuit 8, and an optocoupler output isolation circuit 9.

[0031] This circuit is a closed-loop controlled current amplifier circuit used to amplify the input IGF-IN given by the previous stage and drive the power MOSFET to output a controlled current to the load. The closed-loop control structure described above can accurately control the output current within a certain voltage range, ensuring that the actual output current strictly tracks the input signal, exhibiting good linearity and stability. It is suitable for applications such as protection device testing and secondary circuit current injection. Differential amplification sampling and power supply filtering design effectively suppress common-mode interference and high-frequency noise, ensuring low current output ripple and low waveform distortion, which helps improve test accuracy and the accuracy of the criteria for the device under test. Simultaneously, a comparator optocoupler isolated output circuit is designed, which can promptly report to the main control when the output current is abnormal, facilitating the implementation of current limiting, disconnection, and other protective measures, reducing the risk of damage to power devices and external loads. The specific circuit structure of each part is as follows:

[0032] like Figure 3 As shown, the first buffer circuit 1 includes operational amplifier U1A. The output terminal of operational amplifier U1A is connected to the negative input terminal. The input signal is connected to the positive input terminal of operational amplifier U1A through resistor R11, and the positive input terminal is connected to ground through resistor R12. The first buffer circuit can perform impedance matching to prevent the front-end signal from being distorted due to excessive load, while stabilizing the signal amplitude. The first-stage amplifier circuit 2 includes operational amplifier U1B. The output terminal of operational amplifier U1A is connected to the negative input terminal of operational amplifier U1B through resistor R21. A capacitor C21 and a resistor R22 are connected in parallel between the negative input terminal and the output terminal of operational amplifier U1B. The positive input terminal of operational amplifier U1B is connected to ground through resistor R24, and the output terminal of operational amplifier U1B is connected to resistor R23. In the figure, operational amplifiers U1A and U1B use SGM8249 operational amplifier chips to perform first-stage amplification and filtering of the input IGF-IN. The current setpoint is set by the surrounding resistors and capacitors, and high-frequency noise is suppressed.

[0033] like Figure 5As shown, the differential amplifier circuit 6 includes a differential amplifier chip U5. The two ends of the sampling resistor RW are connected to the differential input terminals of the differential amplifier chip U5 (shown as IFP and IFN). The output terminal of the differential amplifier chip U5 is connected to the second buffer circuit 7. Simultaneously, the output terminal of the differential amplifier chip U5 is connected to the second-stage amplifier circuit 3 through a parallel capacitor C51 and resistor R51. The differential amplifier chip U5 is an INA143U, which amplifies the voltage drop across the sampling resistor RW (between IFP and IFN) in the current output branch to obtain a feedback signal IGF_FK proportional to the actual output current.

[0034] like Figure 4 As shown, the secondary amplifier circuit 3 includes operational amplifier U2A. A resistor R31 and a capacitor C31 are connected between the negative input terminal and the output terminal of operational amplifier U2A. The negative input terminal of operational amplifier U2A is connected to ground through resistor R32. The output terminal of operational amplifier U1B is connected to the negative input terminal of operational amplifier U2A through resistor R23. The reference voltage divider circuit 4 includes a precision reference source chip Q. The output terminal of operational amplifier U2A is connected to the operating power supply through three voltage divider resistors R41, R42, and R43. The anode and cathode of the precision reference source chip Q are connected to the non-connected voltage divider resistors R41 and R42. At both ends, the reference reference terminal of the precision reference source chip Q is connected to the junction of voltage divider resistors R41 and R42. A capacitor C41 is also connected between the anode and cathode of the precision reference source chip Q. The isolation drive circuit 5 includes a MOSFET. A diode D1 is connected between the source and drain of the MOSFET. The drain of the MOSFET is connected to the bus power supply. The output terminal of the operational amplifier U2A is connected to the source of the MOSFET through a resistor R52. A resistor R53 is also connected between the source and gate of the MOSFET. The cathode of the precision reference source chip Q is also connected to the gate of the MOSFET through a resistor R51.

[0035] Figure 5 The three main components shown constitute the current drive stage, consisting of operational amplifier U2A, a precision reference source chip Q (ME431 series), and a power MOSFET. Operational amplifier U2A adjusts the gate voltage of the MOSFET based on the error between the given input and the feedback. The current is sampled through a sampling resistor and input to the differential amplifier chip U5. The feedback signal IGF_FK is sent back to the operational amplifier for comparison, enabling the operational amplifier to control the drive signal of the MOSFET gate and automatically adjust the MOSFET's conduction level, so that the voltage across the sampling resistor (i.e., the output current) approaches the target value of IGF-IN, thus forming a constant current closed loop of "current setting—current sampling—error amplification—MOSFET adjustment".

[0036] like Figure 6As shown, the second buffer circuit 7 includes operational amplifier U2B, the output of which is connected to the negative input terminal. The comparator circuit 8 includes operational amplifier U4A, the positive input terminal of which is connected to ground via resistor R81 and to the operating power supply via resistor R82. The optocoupler output isolation circuit 9 includes operational amplifier U4B and optocoupler U3. The output terminal of operational amplifier U4A is connected to the operating power supply via pull-up resistor R91 and to the positive input terminal of operational amplifier U4B via resistor R92. The positive input terminal of operational amplifier U4B is connected to ground via capacitor C7. The negative input terminal of operational amplifier U4B is connected to ground via resistor R95 and to the operating power supply via resistor R93. The output terminal of operational amplifier U4B is connected to one input terminal of optocoupler U3, and the other input terminal of optocoupler U3 is connected to the operating power supply via resistor R94. Operational amplifier U4A is an LM393 comparator. The second buffer circuit, comparator circuit, optocoupler output isolation circuit, and external resistors and capacitors constitute an overcurrent / abnormal current detection circuit. When the sampling exceeds the set threshold, the comparator output flips and sends an isolated fault / protection signal to the main control system through optocoupler U3 (model CT357C) to protect the current output stage.

[0037] This current amplifier circuit uses an operational amplifier, sampling resistor, and MOSFET as its core to form a constant current amplifier structure. It features high accuracy in output current adjustment, good dynamic response, strong anti-interference capability, and comprehensive protection functions, meeting the application requirements of intelligent substation commissioning devices for current injection and simulated load driving.

[0038] This embodiment also provides an intelligent substation commissioning device, such as... Figure 7 As shown, it includes a main control board, which is connected to a power supply circuit, a digital input / output circuit, and a DAC circuit. The DAC circuit is connected to a current amplifier circuit and a voltage amplifier circuit. The current amplifier circuit uses the current amplifier circuit, the voltage amplifier circuit has a voltage output, and the current amplifier circuit has a current output.

[0039] In specific connections, the main control board is also connected to a PC and an industrial control computer. For intelligent substation commissioning equipment, the operation is as follows: the PC communicates with the main control board via an Ethernet interface. Network data first enters the switch chip inside the main control board, which handles data transmission and reception, enabling the main control board to receive commissioning commands from the host computer and upload collected data and operating status. The industrial control computer interacts with the main control board via a dedicated communication link. The industrial control computer runs the commissioning software, interface logic, and data management program. After receiving the commissioning command, the main control board outputs control words to the high-speed DAC circuit according to the set output parameters. The DAC circuit converts the digital quantity into an analog control quantity and sends it to the downstream power amplifier section. Each power amplifier, through precision amplification, closed-loop feedback, and power device driving, generates accurate and stable current or voltage outputs, realizing analog quantity testing and simulation excitation of external protection devices, relay protection equipment, secondary circuits, etc. The main control board is also connected to the switch input / output circuit. The input circuit isolates and processes external dry contact or status signals before sending them to the main control board for identification of tripping and status signals from protection devices. The output section drives output branches according to control commands from the main control board, enabling tripping simulation, activation / deactivation simulation, and event triggering. The power supply circuit provides multiple stable power sources to the main control board, digital input / output circuits, high-speed DAC circuits, and current / voltage power amplifier circuits, ensuring the safe and reliable operation of digital, analog, and power amplifier circuits. Through the coordinated operation of the main control board, industrial computer, power supply circuit, high-speed DAC circuit, power amplifier circuit, and digital input / output modules, this device can achieve analog output, digital acquisition and output, debugging process control, and communication with the host computer, providing complete debugging capabilities for on-site testing, commissioning, and verification of secondary equipment in intelligent substations. It should be noted that the debugging process is not the focus of this application; the core of this application lies in the design of the circuit structure.

[0040] For the power supply circuit, such as Figure 8As shown, the circuit includes a first common-mode inductor 11, a first filter network 12, an isolated DC-DC converter module 13, a second filter network 14, a second common-mode inductor 15, and a third filter network 16 connected in sequence. The third filter network 16 outputs the operating power. This power supply circuit is an isolated DC power conversion circuit for industrial environments. Its function is to convert an externally supplied 24V industrial DC power supply into a stable isolated operating power supply required by the equipment. The circuit operation starts from the 24V input terminal. The input power first passes through an input filter network consisting of a first common-mode inductor (ACM7060) and several filter capacitors. This network is used to suppress common-mode interference and pulse noise from the power line, and to absorb and smooth the ripple and transient voltage at the input terminal, making the voltage before entering the isolated power supply module more stable. The power supply after the pre-stage filtering is sent to the isolated DC-DC converter module (model URB2412YMD-10WR3). The module internally achieves electrical isolation between the input and output through a high-frequency transformer, and converts the 24V to a stable DC output through switching regulation. Because the DC-DC converter module generates certain switching ripple during high-frequency operation, the circuit incorporates a secondary filter network (second and third filter networks) at the output, consisting of a second common-mode inductor and multiple filter capacitors, to further suppress high-frequency noise and low-frequency ripple. This ensures a clean and stable output power supply, meeting the power quality requirements of precision circuits. Finally, the stable output power drives an LED indicator via a current-limiting resistor, providing a visual display of the power status. The power is then supplied to the main control board of the entire device via the output terminals, forming a complete power supply chain from input filtering and isolation conversion to output filtering and status indication.

[0041] This power supply circuit constructs a highly reliable industrial power supply system through input and output filtering networks, an isolated DC-DC converter module, and a power status monitoring mechanism. This effectively improves the system's electromagnetic compatibility performance and ensures low ripple and high stability of the output power supply. The isolated DC-DC module effectively reduces the impact of common-mode interference, spike pulses, and ground loop coupling on the core control circuit, thus significantly enhancing the overall reliability and safety of the system in complex industrial electromagnetic environments. The output power supply, after multi-stage filtering, has low noise and low ripple, meeting the power quality requirements of high-precision circuits such as FPGAs, operational amplifiers, and analog power amplifiers, making the analog output signal more stable and reducing offset and errors caused by power fluctuations. Furthermore, the circuit's LED power status indicator provides a clear display of the power supply status, facilitating equipment maintenance and operation monitoring. Overall, this power supply structure is adaptable to intelligent substations, power electronic equipment, and various industrial measurement and control scenarios, providing a reliable power foundation for the long-term stable operation of equipment.

[0042] For the voltage power amplifier circuit, such as Figure 9As shown, the voltage power amplifier circuit adopts a two-stage amplification structure with a pre-stage operational amplifier and a post-stage operational amplifier. The pre-stage operational amplifier U67A (SGM8249-2) is powered by a ±15V dual power supply. Its input terminal is connected to ADUA, and a closed-loop amplification structure is formed through the precision feedback resistor R581, so that U67A operates in a buffered / low-gain amplification state. On the one hand, it increases the input impedance and reduces the load influence on the circuit under test, and on the other hand, it performs preliminary amplification and stabilization of the input signal. Decoupling capacitors C370 and C371 (0.1 μF) are connected in parallel at the power supply terminals of U67A to bypass high-frequency noise and ensure stable operation of the operational amplifier under high gain bandwidth. The output of U67A is fed to the inverting input terminal of the post-stage operational amplifier U66B through the input resistor R579. U66B forms a closed-loop feedback network with the output terminal through resistor R580. Resistors R579 and R580 together set the closed-loop gain of this stage of operational amplifier. Simultaneously, a reference potential is introduced at the input through resistor R578, enabling the subsequent operational amplifier to perform both proportional amplification and bias conditioning functions, ensuring that the output UA signal accurately matches the measurement range. The U66B performs precise amplitude scaling and zero-point correction on the signal from the preceding stage, ensuring that the voltage at the output node UA maintains a linear correspondence with the original ADUA signal, while also meeting the requirements of the input range and common-mode range. The UA node is then connected to the ADC_UA pin via a trace, completing one voltage conditioning process for the acquisition channel.

[0043] Compared to traditional intelligent substation commissioning equipment, this invention achieves higher reliability and measurement / output accuracy. On one hand, the dual-stage filtered industrial computer power module significantly reduces input-side ripple interference, providing a stable, low-noise power supply for the industrial computer and its main control board circuitry. On the other hand, the current output employs differential sampling feedback closed-loop control supplemented by a comparator + optocoupler overcurrent protection structure, enabling the output current to accurately track the control quantity while also providing overload alarm capability, significantly superior to traditional open-loop current output structures. The voltage section, through two-stage operational amplifier buffering and precision resistor network range matching, can operate within the optimal dynamic range, improving the resolution and accuracy of on-site voltage measurements.

[0044] In summary, this utility model not only possesses the analog output and switching quantity testing capabilities required by traditional debugging equipment, but also achieves significant improvements in power supply stability, output accuracy, acquisition accuracy, and overall anti-interference capability, making it more suitable for long-term stable applications in intelligent substations, power protection system debugging, and industrial measurement and control.

[0045] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A current power amplifier circuit, characterized in that: The power amplifier circuit includes a first buffer circuit (1), a first-stage amplifier circuit (2), a second-stage amplifier circuit (3), a reference voltage divider circuit (4), an isolation drive circuit (5), and a sampling resistor RW connected in sequence. One end of the sampling resistor RW is used as the output, and the input signal is input to the first buffer circuit (1). The power amplifier circuit also includes a differential amplifier circuit (6). The two ends of the sampling resistor RW are respectively connected to the differential amplifier circuit (6) as inputs. The output end of the differential amplifier circuit (6) is connected to the second-stage amplifier circuit (3). The output end of the differential amplifier circuit (6) is also connected in sequence to a second buffer circuit (7), a comparator circuit (8), and an optocoupler output isolation circuit (9).

2. The current power amplifier circuit as described in claim 1, characterized in that: The first buffer circuit (1) includes an operational amplifier U1A. The output terminal of the operational amplifier U1A is connected to the negative input terminal. The input signal is connected to the positive input terminal of the operational amplifier U1A through a resistor R11, and the positive input terminal is connected to ground through a resistor R12. The first-stage amplifier circuit (2) includes an operational amplifier U1B. The output terminal of the operational amplifier U1A is connected to the negative input terminal of the operational amplifier U1B through a resistor R21. A capacitor C21 and a resistor R22 are connected in parallel between the negative input terminal and the output terminal of the operational amplifier U1B. The positive input terminal of the operational amplifier U1B is connected to ground through a resistor R24, and a resistor R23 is connected to the output terminal of the operational amplifier U1B.

3. The current power amplifier circuit as described in claim 2, characterized in that: The secondary amplifier circuit (3) includes operational amplifier U2A. A resistor R31 and a capacitor C31 are connected between the negative input terminal and the output terminal of operational amplifier U2A. The negative input terminal of operational amplifier U2A is connected to ground through resistor R32. The output terminal of operational amplifier U1B is connected to the negative input terminal of operational amplifier U2A through resistor R23. The reference voltage divider circuit (4) includes a precision reference source chip Q. The output terminal of operational amplifier U2A is connected to the operating power supply in sequence through three voltage divider resistors R41, R42, and R43. The anode and cathode of the precision reference source chip Q are connected to the non-connected voltage divider resistors R41 and R42 respectively. At both ends, the reference reference terminal of the precision reference source chip Q is connected to the connection point of the voltage divider resistors R41 and R42, and a capacitor C41 is also connected between the anode and cathode of the precision reference source chip Q; the isolation drive circuit (5) includes a MOS transistor, a diode D1 is connected between the source and drain of the MOS transistor, the drain of the MOS transistor is connected to the bus power supply, the output terminal of the operational amplifier U2A is connected to the source of the MOS transistor through a resistor R52, a resistor R53 is also connected between the source and gate of the MOS transistor, and the cathode of the precision reference source chip Q is also connected to the gate of the MOS transistor through a resistor R51.

4. The current power amplifier circuit as described in claim 3, characterized in that: The differential amplifier circuit (6) includes a differential amplifier chip U5. The two ends of the sampling resistor RW are connected to the differential input terminal of the differential amplifier chip U5. The output terminal of the differential amplifier chip U5 is connected to the second buffer circuit (7). At the same time, the output terminal of the differential amplifier chip U5 is connected to the second-stage amplifier circuit (3) through the parallel capacitor C51 and resistor R51.

5. The current power amplifier circuit as described in claim 4, characterized in that: The second buffer circuit (7) includes operational amplifier U2B, the output terminal of operational amplifier U2B is connected to the negative input terminal, the comparator circuit (8) includes operational amplifier U4A, the positive input terminal of operational amplifier U4A is connected to ground through resistor R81, and is connected to the working power supply through resistor R82; the optocoupler output isolation circuit (9) includes operational amplifier U4B and optocoupler U3, the output terminal of operational amplifier U4A is connected to the working power supply through pull-up resistor R91, and is connected to the positive input terminal of operational amplifier U4B through resistor R92, and the positive input terminal of operational amplifier U4B is connected to ground through capacitor C7, the negative input terminal of operational amplifier U4B is connected to ground through resistor R95, and is connected to the working power supply through resistor R93, the output terminal of operational amplifier U4B is connected to one input terminal of optocoupler U3, and the other input terminal of optocoupler U3 is connected to the working power supply through resistor R94.

6. A smart substation commissioning device, characterized in that: The debugging equipment includes a main control board, which is connected to a power supply circuit, a digital input / output circuit, and a DAC circuit. The DAC circuit is connected to a current power amplifier circuit and a voltage power amplifier circuit. The current power amplifier circuit adopts the current power amplifier circuit according to any one of claims 1-5. The voltage power amplifier circuit has a voltage output, and the current power amplifier circuit has a current output.

7. The intelligent substation commissioning equipment as described in claim 6, characterized in that: The power supply circuit includes a first common-mode inductor, a first filter network, an isolated DC-DC converter module, a second filter network, a second common-mode inductor, and a third filter network connected in sequence. The third filter network outputs the operating power supply.

8. The intelligent substation commissioning equipment as described in claim 7, characterized in that: The voltage power amplifier circuit adopts a two-stage amplification structure consisting of a pre-stage operational amplifier and a post-stage operational amplifier.

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