Small signal synchronous adjustable amplification system and method for simulating on-load test

Abstract

The invention discloses a small signal synchronous adjustable amplification system and method for simulating an on-load test, and relates to the field of power system debugging equipment and debugging methods. The existing simulation on-load test equipment and test method have a certain blind area. The circuit comprises a weak voltage signal acquisition unit, a weak current signal acquisition unit, an acquisition signal conversion power output unit, a gain adjustable voltage power unit and a gain adjustable current power unit. The acquisition signal conversion power output unit is connected with the weak voltage signal acquisition unit, the weak current signal acquisition unit, the gain adjustable voltage power unit and the gain adjustable current power unit. According to the technical scheme, a complete micro test signal detection and synchronous amplification system is formed, accurate acquisition, processing and amplification of micro signals are realized, and a flexible gain adjustment function is realized, so that the requirement of a simulation on-load test aiming at the scene in a power system is met.

Description

Technical Field

[0001] The invention relates to the field of power system debugging equipment and debugging methods, and in particular to a tiny signal synchronous adjustable amplification system and method for simulating load tests. Background Art

[0002] In various stations such as substations, converter stations, and power plants in the power system, it is crucial to verify the correctness of the primary and secondary circuits of PTs and CTs. This is not only the basis for ensuring the normal operation of secondary equipment such as relay protection, automation, and metering, but also an important guarantee for the stable operation of the power grid. After years of exploration, research, and experience accumulation by on-site relay protection workers, the simulated load test technology has made great progress. At present, test equipment with high voltage and high current split synchronous output technology as the core has been successfully developed, and related supporting test plans have been formed.

[0003] However, with the increase in grid voltage levels and the diversification of equipment properties, the above-mentioned test equipment has gradually exposed its limitations in some test scenarios. Especially in scenarios such as primary voltage application of voltage transformers at voltage levels of 220kV and above and primary current injection of transformers, reactors, grounding transformers, filters and other equipment, due to the voltage, power and other parameter limitations of the current-passing pressure-passing equipment, the secondary voltage or current signal generated during the test may be extremely weak, even as low as 0.1V or below 0.5mA. In this case, existing digital multimeters or clamp-on phase meters are often unable to measure accurately, and secondary equipment such as protection, measurement and control cannot display correctly, resulting in blind spots in the implementation of simulated load tests for some equipment.

[0004] In order to overcome this problem, the present invention proposes to develop a system capable of accurately detecting and synchronously amplifying tiny test signals and a matching simulated load test method, thereby strengthening the existing simulated load test method system. Summary of the invention

[0005] The technical problem to be solved and the technical task proposed by the present invention are to improve and strengthen the existing technical solutions, and provide a small signal synchronous adjustable amplification system and method for simulating load test, so as to meet the needs of PT and CT primary and secondary circuit correctness testing at various stations of the power system. To this end, the present invention adopts the following technical solutions.

[0006] A tiny signal synchronous adjustable amplification system for simulating load test, including a tiny signal synchronous adjustable amplification system including a signal acquisition unit, a collection signal conversion power output unit, a gain adjustable voltage power unit and a gain adjustable current power unit, the signal acquisition unit includes a weak voltage signal acquisition unit and a weak current signal acquisition unit, the collection signal conversion power output unit is respectively connected to the weak voltage signal acquisition unit, the weak current signal acquisition unit, the gain adjustable voltage power unit and the gain adjustable current power unit, and is used to process logical operations and control test procedures. The tiny signal synchronous adjustable amplification system for simulating load test is used for scenarios where tiny test signals are generated when the power system simulates load test.

[0007] This technical solution integrates multiple units such as weak voltage signal acquisition, weak current acquisition, signal conversion power output, gain-adjustable voltage power and gain-adjustable current power, and forms a complete tiny test signal detection and synchronous amplification system by integrating the acquisition signal conversion power output unit to perform logical operations and control the connection of the test process. The system can efficiently process tiny test signals and realize synchronous amplification of signals, and has a flexible gain adjustment function to achieve accurate acquisition, processing and amplification of tiny signals, thereby meeting the needs of correctness testing of primary and secondary circuits of PT and CT in power systems.

[0008] As a preferred technical means: the weak voltage signal acquisition unit is used to collect tiny voltage signals within the range of ±10V. The sampling rate of the weak voltage signal acquisition unit is 100k, that is, one point in 10μs. By collecting these tiny signals, the unit can ensure the accuracy of the test data and provide a reliable basis for subsequent signal processing and amplification.

[0009] As a preferred technical means: the weak current signal acquisition unit has two ranges of 0-20mA and 20mA-1A, and the sampling rate of the weak current signal acquisition unit is 100k, that is, one point every 10μs, which is used to collect tiny current signals. It can cover a variety of current test requirements, so that the system can flexibly respond to tests in different current ranges, improving the accuracy and applicability of the test.

[0010] As a preferred technical means: the gain adjustable voltage power unit is used to output AC voltage in the range of 0-120V, and is provided with a short circuit protection interface and an overload protection interface. It can not only meet the needs of different voltage tests, but also ensure the safety and stability of voltage output, and can effectively prevent equipment damage or safety accidents caused by abnormal voltage.

[0011] As a preferred technical means: the gain adjustable current power unit is used to output AC current in the range of 0-1A, and is provided with an overheating interface and an open circuit protection interface. This makes the current output more stable and reliable, and at the same time protects the device from abnormal conditions such as overheating and open circuit, thereby improving the accuracy and safety of the test.

[0012] As a preferred technical means: the acquisition signal conversion power output unit is connected to the weak voltage signal acquisition unit and the weak current signal acquisition unit through a parallel data bus to transmit weak voltage signals. High-speed and stable data transmission is achieved. This connection method ensures that weak voltage and current signals can be accurately and timely transmitted to subsequent processing units, improving the response speed and accuracy of the entire system. The acquisition signal conversion power output unit is equipped with a display screen and a mouse, and can set the gain of the gain-adjustable voltage power unit and the gain-adjustable current power unit.

[0013] As a preferred technical means: the acquisition signal conversion power output unit is connected to the weak current signal acquisition unit via a parallel data bus for transmitting weak current signals. This achieves fast and accurate transmission of current signals, helps ensure the integrity and real-time performance of current signals, and provides a reliable data source for subsequent signal processing and amplification.

[0014] As a preferred technical means: the acquisition signal conversion power output unit and the gain adjustable voltage power unit are connected via an SPI bus to transmit control signals and voltage output signals. This achieves stable transmission of control signals and voltage output signals. This connection method simplifies the system structure, improves the efficiency and reliability of data transmission, and reduces system costs.

[0015] As a preferred technical means: the acquisition signal conversion power output unit and the gain adjustable current power unit are connected via an SPI bus for transmitting control signals and current output signals. Stable transmission of control signals and current output signals is achieved, which helps to ensure the accuracy and stability of current output and improves the performance and reliability of the entire system.

[0016] As a preferred technical means: the system also includes a signal synchronization unit, which is used to ensure that the time difference between the input signal and the output signal is less than 100μs, so as to achieve synchronous amplification of the signal. The acquisition signal conversion power output unit collects the data of the weak voltage signal acquisition unit and the weak current signal acquisition unit in a period of 10μs and simultaneously sends them to the gain-adjustable voltage power unit and the gain-adjustable current power unit to ensure that the time difference between the input signal and the output signal is less than 100μs, so as to achieve synchronous amplification of the signal. This design is crucial for test scenarios that require high-precision synchronization, and can ensure the accuracy and reliability of the test results. At the same time, it also meets the high requirements for signal synchronization in application scenarios such as power system substations, converter stations, and power plants.

[0017] As a preferred technical means: the acquisition unit includes a connector P5, a connector P3, an operational amplifier U9, a connector P1, a relay J1 and a connector P2; the pin 1 of the operational amplifier U9 is respectively connected to one end of the resistor R50 and the pin 5 of the relay J1; the pin 2 of the operational amplifier U9 is respectively connected to the other end of the resistor R50 and one end of the resistor R52, and the other end of the resistor R52 is connected to the ground; the pin 3 of the operational amplifier U9 is respectively connected to the pin 1 of the connector P3 and the pin 7 of the relay J1, the pin 4 of the operational amplifier U9 is respectively connected to the power supply -15V and one end of the capacitor C19, and the other end of the capacitor C19 is connected to the ground wire; the pin 5 of the operational amplifier U9 is respectively connected to the pin 2 of the connector P3 and the pin 2 of the relay J1 , pin 6 of the operational amplifier U9 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the ground wire, and the other end of the resistor R1 is respectively connected to pin 7 of the operational amplifier U9 and pin 4 of the relay J1; pin 8 of the operational amplifier U9 is respectively connected to the power supply +15V and one end of the capacitor C17, and the other end of the capacitor C17 is connected to the ground wire; pin 1 of the relay J1 is respectively connected to one end of the diode D1 and one end of the diode D2, the other end of the diode D1 is connected to pin 3 of the connector P1, and the other end of the diode D2 is respectively connected to the ground wire and pin 8 of the relay J1; pin 6 of the relay J1 is connected to pin 1 of the connector P2, and pin 3 of the relay J1 is connected to pin 2 of the connector P2.

[0018] The operational amplifier U9 in this technical solution plays a key role, which can effectively amplify the input weak signal, making it easier to be received and further processed by subsequent processing modules (such as gain-adjustable voltage power units and current power units). In particular, the gain of voltage signals and accurate current signal measurement can support the accurate acquisition of tiny signals. Relay J1 acts as a switching element in the circuit to isolate and convert signals. The role of the relay is not only to disconnect and connect the circuit, but also to ensure that the signal is transmitted to the designated module at the appropriate time through its control, while avoiding direct current or voltage interference. Through the configuration of resistors (such as R50, R1, R2) and capacitors (such as C17, C19), a suitable filtering effect is provided to reduce noise and interference in the signal. In addition, the diodes (D1, D2) used in the relay can effectively prevent damage to the circuit caused by reverse current and overcurrent.

[0019] The connection method of connectors (P1, P2, P3, P5) and relays ensures that the circuit can be flexibly connected to other systems or modules and supports signal transmission and power amplification. Through this modular design, the circuit can be adjusted and expanded according to different application requirements.

[0020] When a weak voltage or current signal is input into the system, the operational amplifier U9 will initially amplify it. The signal is properly adjusted and filtered through components such as resistors R50 and R1 to enhance the clarity of the signal and remove high-frequency noise. After gain adjustment, the signal enters the relay (J1) for further switching and transmission. The signal after circuit conditioning will be transmitted to the subsequent signal conversion and power output unit through connectors (such as P1 and P2) for gain-adjustable output. At this point, the system can output AC voltage or current signals of corresponding amplitudes as needed.

[0021] Another object of the present invention is to provide a method for simulating load testing using the aforementioned small signal synchronous adjustable amplification system for simulating load testing. The method for simulating load testing comprises the following steps: 1) Select a suitable position to disconnect the secondary circuit of the corresponding secondary winding of the voltage transformer PT or current transformer CT that needs to be amplified; 2) A small signal synchronous adjustable amplification system for simulating load test is connected at the disconnection point, the secondary winding side of the PT or CT is connected to the input end of the amplification system, and the output end of the amplification system is connected to the load side of the disconnection point; 3) After adding the test quantity to the primary side of the PT or CT and generating a small test signal on the secondary side, the amplification system can synchronously amplify the voltage or current signal according to the set gain multiple and input it into the secondary circuit on the load side, helping the test personnel to accurately judge the correctness of the transformation ratio and polarity of the PT and CT.

[0022] This method can provide efficient signal amplification and processing for tiny voltage or current signals on the secondary circuit in power system tests. Traditional methods often have problems such as signal distortion and noise interference in the collection and processing of tiny signals. By adopting a synchronous adjustable amplification system, tiny signals can be accurately amplified to avoid distortion, thereby ensuring the accuracy of the test results.

[0023] The synchronous amplification function enables the system to perform high-fidelity synchronous amplification of the input tiny signal, ensuring that the amplified signal is consistent with the original signal, thereby effectively eliminating the test error caused by asynchrony or time lag. This is very important for testing and debugging the transformation ratio, polarity and other characteristics of PT (voltage transformer) and CT (current transformer), avoiding misjudgment due to synchronization error.

[0024] The adjustable gain function of the system allows users to adjust the gain multiples as needed under different test conditions to adapt to different types of voltage or current signals. This flexibility enables the system to work efficiently in a variety of power test scenarios and meet the needs of different tests.

[0025] By synchronously amplifying the signal, testers can more easily and accurately determine the correctness of the wiring of the primary and secondary circuits of PTs and CTs, including whether their transformation ratios and polarities meet the requirements. This can effectively avoid system failures or inaccurate measurements caused by incorrect wiring.

[0026] This method can be expanded on the basis of existing simulated load test equipment, so there is no need to redesign or significantly modify the existing system. It reduces the implementation cost and can improve the performance of existing equipment without increasing complexity, and put it into use quickly. Through efficient synchronous amplification and gain adjustment of small signals, testers can quickly and accurately obtain the amplification results of signals, reduce the complexity and possible errors of manual judgment, thereby improving work efficiency and shortening test time.

[0027] Beneficial effects: Under the premise of using the existing simulated load test equipment, the system can efficiently and accurately process the secondary tiny test signal. When only a tiny current or voltage signal can be generated on the secondary circuit during the test, the small signal can be detected without distortion, and the synchronous amplification and output of the signal can be achieved. It also has a flexible gain adjustment function, which can realize the accurate collection, processing and amplification of tiny signals, so that on-site debugging personnel can easily judge the correctness of the primary and secondary wiring of PT and CT, and meet the needs of correctness testing of the primary and secondary circuits of PT and CT in the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a connection block diagram of the present invention.

[0029] Figure 2 It is a partial schematic diagram of the present invention.

[0030] Figure 3 This is a typical application scenario of the present invention in CT testing.

[0031] Figure 4 This is a typical application scenario of the present invention in PT test. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0033] Embodiment 1: like Figure 1 As shown, it is a connection block diagram of a small signal synchronous adjustable amplification system for simulating load test. The present invention includes a weak voltage signal acquisition unit, a weak current signal acquisition unit, an acquisition signal conversion power output unit, a gain adjustable voltage power unit and a gain adjustable current power unit. The acquisition signal conversion power output unit is respectively connected with the weak voltage signal acquisition unit, the weak current signal acquisition unit, the gain adjustable voltage power unit and the gain adjustable current power unit. In this example, the acquisition signal conversion power output unit adopts an ADSP-BF607 chip for processing logical operations and controlling the test process. By integrating multiple units such as weak voltage signal acquisition, weak current acquisition, signal conversion power output, gain adjustable voltage power and gain adjustable current power, and connecting the acquisition signal conversion power output unit to perform logical operations and control the test process, a complete small test signal detection and synchronous amplification system is formed.

[0034] In order to accurately collect tiny signals, the weak voltage signal acquisition unit uses the AD7606 chip to collect tiny voltage signals within the range of ±10 V. By accurately collecting these tiny signals, the unit can ensure the accuracy of the test data and provide a reliable basis for subsequent signal processing and amplification.

[0035] In order to be able to flexibly cope with tests in different current ranges, the weak current signal acquisition unit uses the AD7606 chip, which has two ranges of 0-20mA and 20mA-1A, for collecting tiny current signals. It can cover a variety of current test requirements, allowing the system to flexibly cope with tests in different current ranges, improving the accuracy and applicability of the test.

[0036] In order to ensure the safety and stability of voltage output, the gain adjustable voltage power unit uses LTC2704 chip to output AC voltage in the range of 0-120V, and is equipped with short circuit protection interface and overload protection interface. It can not only meet the needs of different voltage tests, but also ensure the safety and stability of voltage output, and can effectively prevent equipment damage or safety accidents caused by abnormal voltage.

[0037] In order to make the current output more stable and reliable, the gain-adjustable current power unit uses the AD5781 chip to output AC current in the range of 0-1A, and is equipped with an overheating interface and an open circuit protection interface. This makes the current output more stable and reliable, while protecting the device from abnormal conditions such as overheating and open circuit, improving the accuracy and safety of the test.

[0038] In order to improve the response speed and accuracy of the entire system, the acquisition signal conversion power output unit is connected to the weak voltage signal acquisition unit through a parallel data bus to transmit weak voltage signals. High-speed and stable data transmission is achieved. This connection method ensures that the weak voltage signal can be accurately and timely transmitted to the subsequent processing unit, improving the response speed and accuracy of the entire system. The acquisition signal conversion power output unit has a display screen and a mouse, which can adjust and set the gain of the voltage power unit and the current power unit.

[0039] In order to achieve fast and accurate transmission of current signals, the acquisition signal conversion power output unit and the weak current signal acquisition unit are connected through a parallel data bus to transmit weak current signals. The fast and accurate transmission of current signals is achieved, which helps to ensure the integrity and real-time performance of current signals and provides a reliable data source for subsequent signal processing and amplification.

[0040] In order to achieve stable transmission of control signals and voltage output signals, the acquisition signal conversion power output unit and the gain adjustable voltage power unit are connected through the SPI bus to transmit control signals and voltage output signals. Stable transmission of control signals and voltage output signals is achieved. This connection method simplifies the system structure, improves the efficiency and reliability of data transmission, and reduces system costs.

[0041] In order to achieve stable transmission of control signals and current output signals, the acquisition signal conversion power output unit and the gain adjustable current power unit are connected through the SPI bus to transmit control signals and current output signals. Stable transmission of control signals and current output signals is achieved, which helps to ensure the accuracy and stability of current output and improves the performance and reliability of the entire system.

[0042] In order to improve the requirements for signal synchronization and ensure the accuracy and reliability of the test results, the acquisition signal conversion power output unit collects the data of the weak voltage signal acquisition unit and the weak current signal acquisition unit at a period of 10μs and simultaneously sends them to the gain-adjustable voltage power unit and the gain-adjustable current power unit to ensure that the time difference between the input signal and the output signal is less than 100μs to achieve synchronous amplification of the signal. This design is crucial for test scenarios that require high-precision synchronization, which can ensure the accuracy and reliability of the test results, and also meet the high requirements of secondary equipment such as relay protection, measurement and control in power systems for the synchronization of current and voltage signals.

[0043] Figure 2 The figure shows a partial schematic diagram of a small signal synchronous adjustable amplification system for simulating load test of the present invention. The acquisition unit includes connector P5, connector P3, operational amplifier U9, connector P1, relay J1 and connector P2; pin 1 of operational amplifier U9 is respectively connected to one end of resistor R50 and pin 5 of relay J1; pin 2 of operational amplifier U9 is respectively connected to the other end of resistor R50 and one end of resistor R52, and the other end of resistor R52 is connected to ground; pin 3 of operational amplifier U9 is respectively connected to pin 1 of connector P3 and pin 7 of relay J1, pin 4 of operational amplifier U9 is respectively connected to power supply -15V and one end of capacitor C19, and the other end of capacitor C19 is connected to ground; pin 5 of operational amplifier U9 is respectively connected to pin 2 of connector P3 and pin 2 of relay J1, and pin 6 of operational amplifier U9 is respectively connected to pin 7 of connector P3 and one end of capacitor C19, and the other end of capacitor C19 is connected to ground. Pin 6 of the operational amplifier U9 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the ground wire, and the other end of the resistor R1 is respectively connected to pin 7 of the operational amplifier U9 and pin 4 of the relay J1; pin 8 of the operational amplifier U9 is respectively connected to the power supply +15V and one end of the capacitor C17, and the other end of the capacitor C17 is connected to the ground wire; pin 1 of the relay J1 is respectively connected to one end of the diode D1 and one end of the diode D2, the other end of the diode D1 is connected to pin 3 of the connector P1, and the other end of the diode D2 is respectively connected to the ground wire and pin 8 of the relay J1; pin 6 of the relay J1 is connected to pin 1 of the connector P2, and pin 3 of the relay J1 is connected to pin 2 of the connector P2.

[0044] Among them, the pin 3 of the operational amplifier U9 is the input signal UIN_4, which passes through the resistor R50 of the pin 1 and the resistor R52 of the pin 2. The calculation formula of the gain K is: K=1+ =1+ =10 Output pin 1 is 10 times the input signal; pin 5 of operational amplifier U9 is input signal UIN_3, passing through resistor R2 at pin 6 and resistor R1 at pin 7. The calculation formula of gain K is: K=1+ =1+ =10 The output of pin 7 is 10 times the input signal.

[0045] Figure 2 The principle of small signal amplification in the present invention is demonstrated. The amplification of voltage and current signals uses the principle described in the figure. The circuit has efficient and stable signal acquisition and amplification functions, and is particularly suitable for processing weak voltage and current signals, and can provide an accurate signal source for subsequent gain adjustment and power output. It has anti-interference ability, overcurrent protection and reliable circuit isolation functions, ensuring stable signal transmission, and the system has strong compatibility and can adapt to different application requirements.

[0046] Figure 3 This is a typical application scenario of the present invention for CT testing. This scenario tests the first-end bushing CT and the end-end bushing CT of the reactor. First, the secondary circuit terminal blocks of the first-end bushing CT and the end-end bushing CT of the reactor are cut open, and the amplification system is connected to the secondary circuit as shown in the diagram. Then, a primary current injection device is used to inject a primary test current between the first and last ends of the reactor. At this time, a small current signal will be generated in the secondary windings of the first-end bushing CT and the end-end bushing CT. The amplification system is set to a suitable gain multiple and the amplification device is started. The amplified current is input into the original secondary circuit. The test personnel can use a clamp phase meter at the reactor protection terminal block for measurement verification, or directly check the correctness of the differential current display in the protection device.

[0047] Figure 4 This is a typical application scenario of the present invention applied to PT testing. This scenario tests a 500kV capacitive voltage transformer (CVT). First, the CVT secondary circuit terminal block is cut open, and the amplification system is connected to the secondary circuit as shown in the diagram. Then, a primary test voltage is added to the high-voltage side of the CVT using a primary pressure-applying device. At this time, a small voltage signal is generated on the secondary winding side. The amplification system is set to a suitable gain multiple and started. The amplified voltage is input into the original secondary circuit. The tester can use a digital multimeter or other equipment at the secondary cabinet terminal block for measurement verification, or directly check the correctness of the voltage display in the protection, measurement and control system.

[0048] Embodiment 2: The steps of the simulated load test using the present invention are as follows: S1: Select a suitable position to disconnect the secondary circuit of the corresponding secondary winding of the PT or CT to be amplified; S2: Connect the amplification system of the present invention at the disconnection point, connect the secondary winding side of the PT or CT to the input end of the amplification system, and connect the output end of the amplification system to the load side of the disconnection point; S3: After adding the test quantity to the primary side of the PT or CT and generating a small test signal on the secondary side, the amplification system can synchronously amplify the voltage or current signal according to the set gain multiple and input it into the secondary circuit on the load side. The test personnel can accurately judge the transformation ratio, polarity and correctness of the secondary circuit wiring of the PT and CT based on this.

[0049] The present invention can expand the application scenarios of simulated load tests to the main bushing CT of high-impedance transformers, reactors, grounding transformers, filters and other components, and can also greatly improve the primary voltage-passing effect of PTs of voltage levels of 220kV and above, thereby effectively expanding the test scenarios of simulated load tests, and strengthening the blind spots that existed in previous tests. It effectively reduces the risk of incorrect operation of secondary systems such as relay protection when equipment is put into operation, reduces the steps of adjusting the grid operation mode and switching operations, shortens the duration of grid risks, and improves the efficiency of commissioning new grid equipment and the level of grid risk management and control.

[0050] The above-mentioned small signal synchronous adjustable amplification system and method for simulating load testing is a specific embodiment of the present invention, which has embodied the outstanding substantial features and remarkable progress of the present invention. According to actual use needs and under the guidance of the present invention, equivalent modifications in shape, structure, test scenarios, etc. can be made to the system and method, which are all within the scope of protection of the present invention.

Claims

1. A synchronous adjustable amplification system for small signals used to simulate load tests, characterized in that: The tiny signal synchronous adjustable amplification system includes a signal acquisition unit, an acquisition signal conversion power output unit, a gain adjustable voltage power unit and a gain adjustable current power unit. The signal acquisition unit includes a weak voltage signal acquisition unit and a weak current signal acquisition unit. The acquisition signal conversion power output unit is respectively connected to the weak voltage signal acquisition unit, the weak current signal acquisition unit, the gain adjustable voltage power unit and the gain adjustable current power unit for processing logical operations and controlling test processes.

2. According to claim 1, a small signal synchronous adjustable amplification system for simulating load test is characterized in that: The weak voltage signal acquisition unit is used to acquire a tiny voltage signal within the range of ±10V, and the weak current signal acquisition unit has two ranges of 0-20mA and 20mA-1A, and is used to acquire a tiny current signal.

3. The small signal synchronous adjustable amplification system for simulating load test according to claim 1 is characterized in that: The gain-adjustable voltage power unit is used to output an AC voltage in the range of 0-120V, and is provided with a short-circuit protection interface and an overload protection interface; the gain-adjustable current power unit is used to output an AC current in the range of 0-1A, and is provided with an overheating interface and an open-circuit protection interface.

4. The synchronous adjustable amplification system for small signals used for simulating load test according to claim 1 is characterized in that: The acquisition signal conversion power output unit is connected to the weak voltage signal acquisition unit via a parallel data bus for transmitting weak voltage signals; the acquisition signal conversion power output unit is connected to the weak current signal acquisition unit via a parallel data bus for transmitting weak current signals.

5. The synchronous adjustable amplification system of a tiny signal for simulating a load test according to claim 1 is characterized in that: The acquisition signal conversion power output unit is connected to the gain adjustable voltage power unit via an SPI bus for transmitting control signals and voltage output signals; the acquisition signal conversion power output unit is connected to the gain adjustable current power unit via an SPI bus for transmitting control signals and current output signals.

6. The synchronous adjustable amplification system for small signals used for simulating load test according to claim 1 is characterized in that: The system also includes a signal synchronization unit, which is used to ensure that the time difference between the input signal and the output signal is less than 100 μs, so as to achieve synchronous amplification of the signal.

7. The synchronous adjustable amplification system for small signals used for simulating load test according to claim 2 is characterized in that: The acquisition unit includes a connector P5, a connector P3, an operational amplifier U9, a connector P1, a relay J1 and a connector P2; the pin 1 of the operational amplifier U9 is respectively connected to one end of the resistor R50 and the pin 5 of the relay J1; the pin 2 of the operational amplifier U9 is respectively connected to the other end of the resistor R50 and one end of the resistor R52, and the other end of the resistor R52 is connected to the ground; the pin 3 of the operational amplifier U9 is respectively connected to the pin 1 of the connector P3 and the pin 7 of the relay J1, the pin 4 of the operational amplifier U9 is respectively connected to the power supply -15V and one end of the capacitor C19, and the other end of the capacitor C19 is connected to the ground wire; the pin 5 of the operational amplifier U9 is respectively connected to the pin 2 of the connector P3 and the pin 2 of the relay J1, Pin 6 of the operational amplifier U9 is respectively connected to one end of the resistor R1 and one end of the resistor R2, the other end of the resistor R2 is connected to the ground wire, and the other end of the resistor R1 is respectively connected to pin 7 of the operational amplifier U9 and pin 4 of the relay J1; pin 8 of the operational amplifier U9 is respectively connected to the power supply +15V and one end of the capacitor C17, and the other end of the capacitor C17 is connected to the ground wire; pin 1 of the relay J1 is respectively connected to one end of the diode D1 and one end of the diode D2, the other end of the diode D1 is connected to pin 3 of the connector P1, and the other end of the diode D2 is respectively connected to the ground wire and pin 8 of the relay J1; pin 6 of the relay J1 is connected to pin 1 of the connector P2, and pin 3 of the relay J1 is connected to pin 2 of the connector P2.

8. A method for simulating load testing of a power system using the small signal synchronous adjustable amplification system for simulating load testing as claimed in claim 1, characterized in that The following steps are involved: 1) Select a suitable position to disconnect the secondary circuit of the corresponding secondary winding of the voltage transformer PT or current transformer CT that needs to be amplified; 2) A small signal synchronous adjustable amplification system for simulating load test is connected at the disconnection point, the secondary winding side of the PT or CT is connected to the input end of the amplification system, and the output end of the amplification system is connected to the load side of the disconnection point; 3) After adding the test quantity to the primary side of the PT or CT and generating a small test signal on the secondary side, the amplification system can synchronously amplify the voltage or current signal according to the set gain multiple and input it into the secondary circuit on the load side. The test personnel can accurately judge the transformation ratio, polarity and correctness of the secondary circuit wiring of the PT and CT based on this.

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