Analog test system for an isolation transformer

Abstract

This disclosure provides a simulation testing system for an isolation transformer. The system includes: a test power supply, an operating switch, a current-limiting adjustment unit, an intermediate test transformer, a phase-selective closing switch, a fault simulation device, and a test station. The test power supply provides electrical energy to the simulation testing system. The operating switch is connected to the test power supply and controls its activation and deactivation. The current-limiting adjustment unit adjusts the equivalent impedance of the test circuit to control the short-circuit current parameters. The intermediate test transformer achieves voltage level matching. The phase-selective closing switch controls the trigger phase angle of the short-circuit fault. The fault simulation device simulates secondary-side short circuits or internal winding short circuits that may occur during the operation of the isolation transformer. The test station is used to install the isolation transformer under test.

Description

Technical Field

[0001] This disclosure generally relates to the field of simulation testing technology, and more particularly to a simulation testing system for an isolation transformer. Background Technology

[0002] Isolation transformers are widely used for electrical isolation, voltage transformation, and system safety protection. Their operational reliability directly affects the stability of the entire power supply system and the safety of electrical equipment. Especially in complex environments such as coal mining faces where load changes are drastic, isolation transformers not only withstand large load fluctuations for extended periods but may also frequently encounter power grid disturbances and fault impacts.

[0003] During the actual operation of isolation transformers, the power supply system may encounter extreme operating conditions. Therefore, how to safely, controllably, and realistically simulate the short-circuit conditions that isolation transformers may encounter in actual operation under test conditions has become an urgent technical problem to be solved. Summary of the Invention

[0004] This disclosure provides a simulation test system for isolation transformers to address some of the shortcomings mentioned in the background art.

[0005] This disclosure provides a simulation test system for an isolation transformer, including: a test power supply, an operating switch, a current limiting adjustment unit, an intermediate test transformer, a phase selection closing switch, a fault simulation device, and a test station; The test power supply provides electrical energy to the simulation test system; the operating switch is connected to the test power supply and controls its activation and deactivation; the current limiting adjustment unit adjusts the equivalent impedance of the test circuit to control the short-circuit current parameters; the intermediate test transformer achieves voltage level matching; the phase selection closing switch controls the trigger phase angle of the short-circuit fault; the fault simulation device simulates secondary side short circuits or internal winding short circuits that may occur during the operation of the isolation transformer; and the test station is used to install the isolation transformer under test.

[0006] In one embodiment of the first aspect, the current limiting adjustment unit includes: a current limiting reactor and an adjusting resistor; The current-limiting reactor is used to limit the peak value of the short-circuit current; the regulating resistor is used to regulate the effective value of the short-circuit current.

[0007] In one embodiment of the first aspect, it further includes: a measuring device; The measuring equipment includes: a current measuring device and a voltage measuring device; The current measuring device is used to collect current parameters during the simulation test; the voltage measuring device is used to collect voltage parameters during the simulation test.

[0008] In one embodiment of the first aspect, when the simulation test is a simulated external short-circuit test, the output terminal of the test power supply is connected to the operating switch and the current limiting adjustment power supply; the output terminal of the current limiting adjustment unit is connected to the input terminal of the test station; the output terminal of the test station is connected to the primary winding of the intermediate test transformer; the test station is connected to the secondary winding of the intermediate test transformer T by tapping, for simulating secondary short circuit or internal short circuit conditions of the winding.

[0009] In one embodiment of the first aspect, the current measuring device is connected in series between the current limiting adjustment unit and the primary winding of the intermediate test transformer to collect short-circuit current and inrush current; the voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test.

[0010] In one embodiment of the first aspect, when the simulation test is a simulated internal short-circuit test, the output terminal of the test power supply is connected to the operating switch and the current limiting adjustment power supply; the output terminal of the current limiting adjustment unit is connected to the primary winding of the intermediate test transformer; the secondary winding of the intermediate test transformer is connected to the input terminal of the test station through the phase selection closing tube, for providing test voltage to the isolation transformer under test.

[0011] In one embodiment of the first aspect, the current measuring device includes a first current measuring device and a second current measuring device. The first current measuring device is connected in series in the circuit between the intermediate test transformer and the test station to collect the short-circuit current and inrush current of the main test circuit. The second current measuring device is connected in series in the circuit between the test station and the fault simulation device to collect the short-circuit fault current of the fault simulation branch. The voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test. The test main circuit is the main path for supplying normal power to the isolation transformer under test, generating inrush current, and providing working voltage; the fault simulation branch is the path for triggering a secondary side short circuit or an internal short circuit in the winding.

[0012] In one embodiment of the first aspect, when the simulation test is a simulated external short-circuit test, the fault simulation device is kept in the off state, and the power supply is turned on by controlling the operation switch to close, so that the isolation transformer under test can be put into operation under no-load conditions. The voltage measuring device and the current measuring device collect voltage and current data in real time at the instant the operating switch is closed, which are used to determine the inrush current characteristics of the isolation transformer under test and obtain the first simulated test result of the isolation transformer under test.

[0013] In one embodiment of the first aspect, when the simulation test is a simulated internal short circuit test, the phase-selective closing switch is controlled to close at a preset phase angle. The normally open node of the even-numbered fault simulation device is closed, forming a short-circuit fault at a preset location; A short-circuit current is applied to the isolation transformer under test to simulate the dynamic process of a short-circuit fault under actual operating conditions, and a short-circuit test is performed on the isolation transformer under test to obtain a second simulation test result.

[0014] In one embodiment of the first aspect, it further includes: a data analysis module; The device is used to acquire the short-circuit current and short-circuit voltage collected by the voltage measuring device and the current measuring device, and to process the short-circuit current and short-circuit voltage to obtain a first simulation test result or a second simulation test result.

[0015] As will be described in detail below, a simulation testing system for an isolation transformer according to an embodiment of this disclosure is provided. By setting up a test power supply, operating switches, a current-limiting adjustment unit, an intermediate test transformer, a phase-selective closing switch, a fault simulation device, and a test station, the system addresses the issue of isolation transformers being susceptible to load fluctuations, power grid disturbances, and fault impacts under complex operating conditions such as coal mines. Under test conditions, the system dynamically reproduces the short-circuit state of the isolation transformer during actual operation, adapting to changing operating conditions. During the simulation, it reflects the operating characteristics of the isolation transformer in real time and dynamically under different short-circuit trigger phases, different fault types, and different current parameters. This achieves dynamic, realistic, and controllable simulation and dynamic testing verification of the short-circuit condition of the isolation transformer. Therefore, it more closely reflects the dynamic changes of actual complex operating conditions, improves the authenticity and reliability of the test results, and provides accurate and effective test support for the operational reliability and safety protection of the isolation transformer. Attached Figure Description

[0016] Figure 1 An architecture diagram of a simulation test system for an isolation transformer provided in this disclosure embodiment; Figure 2 An architectural diagram of a test platform for a simulation test system of an isolation transformer provided in this disclosure embodiment; Figure 3 This is an architectural diagram of another test platform for a simulation test system of an isolation transformer provided in an embodiment of this disclosure. Detailed Implementation

[0017] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present disclosure and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the drawings, not the entire structure.

[0018] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0019] In this document, the term "and / or" merely describes a relationship, indicating that three relationships can exist. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" in this document means any combination of at least two of any one or more elements. For example, including at least one of A, B, and C can mean including any one or more elements selected from the set consisting of A, B, and C.

[0020] Research has shown that isolation transformers are widely used for electrical isolation, voltage transformation, and system safety protection. Their operational reliability directly affects the stability of the entire power supply system and the safety of electrical equipment. Especially in complex environments such as coal mining faces where load changes are drastic, isolation transformers not only withstand large load fluctuations for extended periods but may also frequently encounter power grid disturbances and fault impacts.

[0021] During the actual operation of isolation transformers, the power supply system may encounter extreme operating conditions. Therefore, how to safely, controllably, and realistically simulate the short-circuit conditions that isolation transformers may encounter in actual operation under test conditions has become an urgent technical problem to be solved.

[0022] Based on the above research, this disclosure provides a simulation test system for an isolation transformer. The test power supply provides stable and continuous power support for the entire test system, ensuring the orderly conduct of various test stages and laying the energy foundation for all subsequent test work. An operating switch controls the on / off state of the power supply circuit, ensuring the test process is startable, stopable, and adjustable, avoiding test risks caused by unexpected power supply. The current limiting adjustment unit precisely controls the magnitude of the short-circuit current during the test by adjusting its own impedance parameters, preventing damage to the test equipment and the product under test due to current overload, and ensuring the safety of the test process. The intermediate test transformer, through voltage level adaptation, converts the test power output... By changing the voltage specifications to meet the requirements of the device under test (DUT), the system's adaptability to different models and parameters of DUTs is broadened, improving the system's versatility. The phase-selective closing switch precisely controls the triggering timing and phase of short-circuit faults, making short-circuit simulation more closely resemble actual operating scenarios and ensuring the authenticity of test conditions. The fault simulation component can reliably simulate typical fault conditions such as secondary side short circuits and internal winding short circuits without damaging the DUT or affecting test safety, meeting short-circuit testing requirements. The test station provides stable installation and electrical connection conditions for the DUT, ensuring the stability of the DUT during the test and guaranteeing the accuracy and repeatability of test data.

[0023] Through efficient collaboration among the various components, a complete and reliable testing system is constructed, effectively solving problems such as insufficient simulation realism, poor test safety, and limited adaptability in isolation transformer testing. It can realistically reproduce various operating conditions in actual operation, providing accurate and reliable test data support for the performance evaluation of the equipment under test, ensuring that the test results are authoritative and of reference value, and providing a guarantee for the design optimization, quality control, and safe operation of isolation transformers.

[0024] To facilitate understanding of this embodiment, a simulation test system for an isolation transformer disclosed in this disclosure will first be described in detail.

[0025] See Figure 1 The diagram shown is an architecture diagram of a simulation test system for an isolation transformer provided in an embodiment of this disclosure, which includes: a test power supply, an operating switch, a current limiting adjustment unit, an intermediate test transformer, a phase selection closing switch, a fault simulation device, and a test station; The system includes: a test power supply for providing power to the simulation test system; an operating switch connected to the test power supply for controlling its activation and deactivation; a current limiting adjustment unit for adjusting the equivalent impedance of the test circuit to control the short-circuit current parameters; an intermediate test transformer for achieving voltage level matching; a phase selection closing switch for controlling the trigger phase angle of short-circuit faults; a fault simulation device for simulating secondary side short circuits or internal winding short circuits that may occur during the operation of the isolation transformer; and a test station for installing the isolation transformer under test.

[0026] In the embodiments of this disclosure, when the operating switch is in the closed state, the test power supply is supplied to the above-mentioned simulation test system; when the operating switch is in the open state, the test power supply is disconnected from the above-mentioned simulation test system.

[0027] Here, the test power supply is the core of the energy supply for the entire simulation test system. It is used to provide electrical energy that meets the requirements of test capacity, voltage level and output stability for the dynamic simulation and short-circuit withstand test of the isolation transformer. It can continuously and reliably provide energy support for the test circuit, ensuring that the voltage and current output do not drop significantly when simulating high current short-circuit impact, inrush current and other conditions, ensuring that various test conditions are established stably, and providing basic power supply guarantee for dynamic simulation and short-circuit withstand test.

[0028] The current limiting adjustment unit is equivalent to the parameter control component of the simulation test system. It is used to control the key indicators such as the effective value, peak value, peak coefficient and duration of the short-circuit current by adjusting the equivalent impedance parameter of the test circuit. This ensures that the short-circuit current strictly meets the requirements of the short-circuit withstand test and can stabilize the short-circuit current within the target tolerance range, avoiding irreversible damage to the transformer under test caused by excessive impact current.

[0029] Here, the intermediate test transformer is a voltage matching and electrical isolation device for simulating the test system. It is used to transform the voltage according to the rated voltage level of the isolation transformer under test, so that the output voltage of the test platform meets the test conditions of the equipment under test, and adapts to the test requirements of isolation transformers with different voltage levels and capacity specifications.

[0030] Among them, the intermediate test transformer can also achieve electrical isolation between the test power supply side and the device under test side, suppress the reverse impact of fault current, reduce test risks, and improve the overall stability and safety protection capabilities of the simulation test system.

[0031] Here, the phase-selective closing switch is a short-circuit phase control device for the simulation test system, used to control the triggering time and phase angle of the short-circuit fault, and can perform the closing action according to the preset voltage phase.

[0032] The phase-selective closing switch can reproduce the short-circuit triggering conditions in the actual power system, so that the simulated short-circuit current waveform, impact characteristics, and transient response are consistent with the actual short-circuit fault.

[0033] Here, the fault simulation device is the working condition simulation mechanism of the simulation test system. It is used to reliably simulate various typical short-circuit faults that may occur in the actual operation of the isolation transformer during the test, including sudden short-circuit faults on the secondary side and short-circuit faults inside the winding. It can complete the triggering and clearing of short-circuit faults under controllable and non-destructive conditions, replacing the traditional destructive test method of direct short-circuit impact, and fully covering the safety performance verification requirements of the main fault scenarios of the isolation transformer.

[0034] Here, the test station is used to install and fix the isolation transformer under test, providing standardized mechanical support and electrical access conditions for the device under test, ensuring that the device under test remains mechanically stable and electrically reliable during dynamic impact and high current tests, and can be adapted to the installation and use of isolation transformers with different shapes and rated parameters, providing stable test foundation conditions for various simulation tests.

[0035] Here, the simulation test system also includes: measuring equipment; The measuring equipment includes: current measuring equipment and voltage measuring equipment; Among them, the current measuring device is used to collect current parameters during the simulation test; the voltage measuring device is used to collect voltage parameters during the simulation test.

[0036] The above embodiments, by setting up a test power supply, operating switches, current limiting adjustment unit, intermediate test transformer, phase selection closing switch, fault simulation device, and test station, can address the problem of isolation transformers being susceptible to load fluctuations, power grid disturbances, and fault impacts under complex working conditions such as coal mines. Under test conditions, the short-circuit state of the isolation transformer during actual operation, varying with operating conditions, is dynamically reproduced. During the simulation, the operating characteristics of the isolation transformer under different short-circuit trigger phases, different fault types, and different current parameters are reflected in real time and dynamically. This achieves dynamic, realistic, and controllable simulation and dynamic testing verification of the short-circuit condition of the isolation transformer. Therefore, it more closely reflects the dynamic changes of actual complex working conditions, improves the authenticity and reliability of test results, and provides accurate and effective test support for the operational reliability and safety protection of isolation transformers.

[0037] In an optional embodiment, the current limiting adjustment unit includes: a current limiting reactor and an adjustment resistor; Among them, the current-limiting reactor is used to limit the peak value of the short-circuit current; the regulating resistor is used to regulate the effective value of the short-circuit current.

[0038] In embodiments of this disclosure, a current-limiting reactor can limit the peak value of the short-circuit current. Specifically, the current-limiting reactor can generate a large inductive reactance, suppressing the instantaneous rise rate of the current, thereby limiting the peak value and peak factor of the short-circuit current.

[0039] By configuring this current-limiting reactor, irreversible electromagnetic shocks and mechanical damage to the intermediate test transformer, the isolation transformer under test, and other test equipment can be prevented due to excessive current surges during short circuits. This improves the safety redundancy of the simulation test process and ensures stability under high current surges.

[0040] Here, the adjusting resistor can adjust the effective value of the short-circuit current. Specifically, by changing the resistance value of the adjusting resistor, the overall equivalent impedance of the simulation test can be altered.

[0041] Here, the target amplitude of the short-circuit current can be set by adjusting the resistor according to the test standards of different models and capacities of the isolation transformer under test, so as to achieve fine and adjustable control of the effective value of the short-circuit current.

[0042] In the above embodiments, the current-limiting reactor and the regulating resistor, through the synergistic effect of inductive and resistive impedances, together constitute the current-limiting regulation unit. They play key roles in peak current control and effective current control, respectively, effectively solving the problem that a single impedance element cannot simultaneously meet peak limit and effective value regulation, thus achieving safe and controllable simulation of dynamic short-circuit conditions of the isolation transformer.

[0043] In an optional embodiment, when the simulation test is a simulated external short-circuit test, the output terminal of the test power supply is connected to the operating switch and the current limiting adjustment power supply; the output terminal of the current limiting adjustment unit is connected to the input terminal of the test station; the output terminal of the test station is connected to the primary winding of the intermediate test transformer; the test station is connected to the secondary winding of the intermediate test transformer T by tapping, in order to simulate the secondary short circuit or the internal short circuit condition of the winding.

[0044] In embodiments of this disclosure, reference is made to Figure 2 The diagram shows the architecture of a test platform for a simulation test system of an isolation transformer provided in this embodiment. The output terminal of the test power supply 1 in the test platform is connected to the current limiting reactor 3 and the regulating resistor 4 in the current limiting adjustment unit via the operation switch 2. The test power supply 1 provides the electrical energy required for the test to the entire test platform. The operation switch 2 is used to control the connection and disconnection of the power supply circuit. The current limiting adjustment unit is used to adjust the equivalent impedance of the circuit to achieve the regulation of the short-circuit current parameter.

[0045] Here, the output of the current limiting adjustment unit is connected to the input of test station 5, which is used to install the isolation transformer under test, providing a stable installation and electrical connection foundation for the device under test. The output of the test station is further connected to the primary winding of the intermediate test transformer 6, which is used to achieve voltage level matching and meet the test voltage requirements of different isolation transformers under test. The fault simulation device 7 is connected to the secondary winding of the intermediate test transformer 6 via a tap, enabling reliable simulation of secondary short-circuit conditions or internal short-circuit conditions of the isolation transformer under this connection method.

[0046] In an optional embodiment, a current measuring device is connected in series between the current limiting adjustment unit and the primary winding of the intermediate test transformer to collect short-circuit current and inrush current; a voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test.

[0047] In embodiments of this disclosure, such as Figure 2 As shown, the current measuring device 11 is connected to the test circuit in series, specifically between the current limiting adjustment unit and the primary winding of the intermediate test transformer 6.

[0048] The voltage measuring device 12 is connected to the test circuit in parallel, specifically at the input terminal of the test station. The test station is used to install the isolation transformer under test, and its input terminal is directly connected to the input terminal of the isolation transformer under test (i.e., test station 5).

[0049] Here, the current measuring device can completely acquire all current signals flowing through the current limiting regulating unit and into the primary winding of the intermediate test transformer. Specifically, the current measuring device can capture the transient changes in current in real time, accurately recording key parameters such as the peak value, effective value, and duration of the short-circuit current, as well as the amplitude and attenuation characteristics of the inrush current, providing data for subsequent analysis of the current limiting regulating unit's control effect.

[0050] Here, the core function of the voltage measurement equipment is to acquire the voltage signal at the input terminal of the isolation transformer under test in real time during the test, including parameters such as the working voltage during the test, transient voltage changes under short-circuit conditions, and voltage response corresponding to inrush current. This can intuitively reflect the port voltage characteristics of the isolation transformer under test under different test conditions.

[0051] In an optional embodiment, when the simulation test is a simulated internal short-circuit test, the output terminal of the test power supply is connected to the current limiting adjustment power supply via an operating switch; the output terminal of the current limiting adjustment unit is connected to the primary winding of the intermediate test transformer; the secondary winding of the intermediate test transformer is connected to the input terminal of the test station via a phase selection closing switch to provide test voltage to the isolation transformer under test.

[0052] In embodiments of this disclosure, reference is made to Figure 3 The diagram shows the architecture of another test platform for a simulation test system of an isolation transformer provided in this embodiment. The output of the test power supply 1 is connected to the current-limiting reactor 3 and the regulating resistor 4 in the current-limiting adjustment unit via the operation switch 2. The output of the regulating resistor 4 is directly connected to the primary winding terminal of the intermediate test transformer 6 to realize the transmission and parameter control of the test power. The secondary winding of the intermediate test transformer 6 is connected to the input of the test station 5 via the phase-selective closing switch 8. The phase-selective closing switch 8 controls the closing timing and phase to ensure stable output of the test voltage. The test station 5 is used to install the isolation transformer under test. Its input terminal and the output terminal of the secondary winding of the intermediate test transformer 6 are reliably electrically connected via the phase-selective closing switch 8. The intermediate test transformer 6 provides a stable test voltage to the isolation transformer under test on the test station 5 to meet the voltage parameter requirements during the internal short-circuit test.

[0053] In an optional embodiment, the current measuring device includes a first current measuring device and a second current measuring device. The first current measuring device is connected in series in the circuit between the intermediate test transformer and the test station to collect the short-circuit current and inrush current of the main test circuit. The second current measuring device is connected in series in the circuit between the test station and the fault simulation device to collect the short-circuit fault current of the fault simulation branch. The voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test. The test main circuit is the main path for supplying normal power to the isolation transformer under test, generating inrush current, and providing working voltage; the fault simulation branch is the path for triggering a short circuit on the secondary side or a short circuit inside the winding.

[0054] In embodiments of this disclosure, such as Figure 3 As shown, the first current measuring device 111 adopts a series connection method and is specifically arranged on the main circuit conductor between the intermediate test transformer 6 and the test station 5, and is directly connected in series on the main current path that flows from the secondary side of the intermediate test transformer 6 to the input terminal of the test station 5.

[0055] The second current measuring device 112 also adopts a series connection method, and is connected in series between the output end of the test station 5 and the input end of the fault simulation device. That is, it is specifically connected to the fault simulation branch circuit used to simulate short-circuit faults, and is used to independently collect the short-circuit fault current when the fault simulation branch is conducting.

[0056] The voltage measuring device 12 adopts a parallel connection method, and its measuring terminals are directly connected in parallel to the input port of the test station 5. Specifically, it is connected in parallel to an electrical node that is compatible with the input terminal of the isolation transformer under test, and can capture the port voltage applied to the terminal of the isolation transformer under test inside the test station in real time.

[0057] In an optional embodiment, when the simulation test is a simulated external short-circuit test, the fault simulation device is kept in the off state, and the power supply is closed by controlling the operation switch to put the isolation transformer under test into operation under no-load conditions. Among them, the voltage measuring device and the current measuring device collect voltage and current data in real time at the moment the operating switch is closed, which is used to determine the inrush current characteristics of the isolation transformer under test and obtain the first simulated test result of the isolation transformer under test.

[0058] In embodiments of this disclosure, when the simulation test is a simulated external short-circuit test (i.e., performing an inrush current test), such as Figure 2 As shown: First, the isolation transformer to be tested is installed at test station 5 according to the test requirements, and all electrical connections are completed. By setting the parameters of the current-limiting reactor 3 and the adjusting resistor 4, the equivalent impedance of the test circuit is adjusted to pre-set the effective value and peak value of the short-circuit current.

[0059] When an inrush current test is required, the fault simulation device 7 is kept in the off state, and the test platform is powered on by operating switch 2, so that the isolation transformer under test is put into operation under no-load conditions. At this time, the voltage measuring device 12 and the current measuring device 11 synchronously collect the voltage and current data at the moment of closing the switch, which are used to analyze the inrush current characteristics and obtain the first simulation test results.

[0060] Here, the test platform can be pre-configured before conducting the inrush current test. For example, a 1250kVA mine explosion-proof isolation transformer can be installed at the test position. The transformer has a primary side rated voltage of 10 kV and a secondary side voltage of 1140 V.

[0061] A 10 kV mains power supply with a capacity of 50 MVA was selected as the test power supply and connected to the system via a vacuum-operated switch. An adjustable air-core reactor was selected as the current-limiting reactor, with an inductance adjustment range of 1 to 5 millihenries. The regulating resistor was a stainless steel grid resistor with a maximum current carrying capacity of 25 kA for 2 seconds.

[0062] The fault simulation device uses a 40 kA vacuum circuit breaker, whose incoming end is connected to the intermediate tap of the secondary winding of the simulated transformer. The tap position corresponds to 50% of the turns ratio.

[0063] After pre-configuring the test platform, an inrush current test can be performed. For example, keep the fault simulation device F in the open state and disconnect the secondary side short circuit path.

[0064] The high-speed waveform recorder with a sampling rate of 200 kHz is simultaneously activated the instant the operation switch is closed. The 0.2-class capacitive voltage divider, used as a voltage measurement device, captures operational overvoltages. With a measured peak voltage of 22.5 kV, it is lower than the 26 kV limit specified in the national standard 1094.

[0065] A 0.1-class Rogowski coil is used as a current measuring device to record the inrush current waveform. The peak value of the first half-wave is limited to 10.8 times the rated current by adjusting the resistance.

[0066] Analysis of inrush current attenuation characteristics: Within 80 milliseconds of actual measurement, the current attenuates to less than 1.5 times the rated current, which meets the mandatory requirements of national standard 1094.1 for inrush current duration.

[0067] In an optional embodiment, when the simulation test is a simulated internal short circuit test, the phase-selective closing switch is controlled to close at a preset phase angle. The normally open node of the even-numbered fault simulation device is closed, forming a short-circuit fault at a preset location; A short-circuit current is applied to the isolation transformer under test to simulate the dynamic process of a short-circuit fault under actual operating conditions. A short-circuit test is then performed on the isolation transformer under test to obtain the second simulation test result.

[0068] In embodiments of this disclosure, the simulated internal short-circuit test includes a secondary-side short-circuit test and an internal short-circuit simulation test. Here, when the simulation test is a simulated internal short-circuit test, such as... Figure 3 As shown, by controlling the phase-selective closing switch 8 to close it at a set phase angle, the normally open node of the fault simulation device 7 is simultaneously triggered to close, creating a short-circuit fault at a predetermined location. At this time, the test platform applies a short-circuit current to the isolation transformer under test under controllable conditions, simulating the dynamic process of encountering a sudden short-circuit fault in actual operation.

[0069] During the short-circuit test, the current-limiting reactor 3 and the regulating resistor 4 work together to control the amplitude, peak value and duration of the short-circuit current; the voltage measuring device 12 and the current measuring device 11 collect key data such as short-circuit current and voltage drop in real time to evaluate the electrical response and safety performance of the isolation transformer under short-circuit impact.

[0070] Here, the test platform can be pre-configured as described above before conducting the simulated internal short-circuit test. Afterwards, the isolation transformer under test can be tested. For example, the fault simulation device can be set to automatically close at the moment the voltage crosses zero, simulating a metallic short circuit at 50% of the secondary winding.

[0071] The measurement system reported key parameters: the first half-wave peak value of the short-circuit current was 19.2 kA, with a duration of 8.3 milliseconds.

[0072] Here, when the primary voltage suddenly drops to 18 percent of the nominal voltage, the isolation transformer under test is determined to be better than the 30 percent critical value specified in industry standard JB / T 501-2021.

[0073] A fiber optic displacement sensor was used to monitor the axial displacement of the transformer winding. The measured maximum deformation was 0.15 mm, which is less than the safety threshold of 0.3 mm.

[0074] Here, the protection performance of the isolation transformer can also be verified. For example, the built-in microprocessor protection device at the forced trigger test station measured a short-circuit fault clearing time of 76 milliseconds. The reliability of the protection logic was verified against the requirements of Clause 3.22 of industry standard JB / T 501-2021. This clause specifies a maximum permissible clearing time of 100 milliseconds.

[0075] Here, a sudden short-circuit heat resistance test can also be performed in the following way: First, parameter calculations are performed. For example, for a 1600 kVA rectifier transformer with a rated voltage of 6.3 kV and an impedance voltage Zts of 6.2%,... The formula for calculating the short-circuit impedance of a transformer is: .

[0076] The minimum short-circuit capacity of the regional power grid is taken as 310 MVA: The formula for calculating system impedance is: .

[0077] The formula for calculating the effective value of symmetrical short-circuit current is: .

[0078] Afterwards, platform adjustments can be performed. For example, a 3000 kVA intermediate test transformer with a turns ratio of 10 kV to 6.3 kV can be selected. Adjust the reactor to an inductance value of 3.8 millihenries to stabilize the short-circuit current within a tolerance range of 13.6 kA ± 2%. Adjust the resistor to 0.05 ohms to control the peak short-circuit current factor to 2.68, which conforms to the range of 2.55 to 2.8 specified in national standard 1094.5.

[0079] Finally, the heat resistance of the isolation transformer under test was verified. For example, a fiber optic temperature measurement system with an accuracy of ±1 degree Celsius was used to monitor the hot spot of the high-voltage winding: during a 2-second period of applying a 13.6 kA current, the hot spot temperature rose from 85 degrees Celsius to a maximum of 218 degrees Celsius. The measured temperature change rate was less than 95 degrees Celsius per second, which is better than the limit of 150 degrees Celsius per second specified in national standard 1094.5.

[0080] After heat resistance verification, post-verification insulation assessment can be performed. For example, a 10 kV insulation resistance tester measures a winding-to-ground insulation resistance greater than 1000 megohms. A 28 kV power frequency withstand voltage test is conducted for one minute without flashover breakdown.

[0081] Here, the simulation testing system can also perform full verification of mining transformers. The verification sequence for full verification of mining transformers is shown in Table 1 below.

[0082] Table 1

[0083] Afterwards, safety verification can be performed. For example, mechanical performance: frequency response analysis after a short-circuit test shows the main resonance peak shift is less than 3%; ultrasonic testing confirms no deformation of the core clamps. Insulation performance: partial discharge test shows a maximum discharge quantity of 8 picocoos and background noise less than 5 picocoos; polarization index (PI) value is greater than 2.0. System compatibility: testing with a mine explosion-proof switchgear shows a protection linkage response time of 82 milliseconds; the effectiveness of the heat dissipation system is verified at an ambient temperature of 85 degrees Celsius.

[0084] Afterwards, optimizations can be performed for specific operating conditions. For example, for mines at altitudes above 2000 meters: the corrected test voltage needs to be multiplied by an altitude coefficient of 1.25; the temperature rise test is extended to 2.5 seconds. A digital signal processor (DSP) is used to calculate the differential of the short-circuit current in real time, controlling the automatic tuning reactor Ls to dynamically adjust the inductance value with an accuracy of ±0.1 millihenries.

[0085] Here, the simulation testing system also includes: a data analysis module; This is used to acquire short-circuit current and short-circuit voltage from voltage and current measuring devices, and to process the short-circuit current and short-circuit voltage to obtain either a first or a second simulated test result.

[0086] The above embodiments have the following technical effects during actual implementation: (1) It can realistically simulate the dynamic short-circuit operation of isolation transformers under safe and controllable conditions.

[0087] This disclosure achieves the simulation of typical dynamic operating conditions such as inrush current, sudden short circuit on the secondary side, and internal short circuit in the winding by the coordinated configuration of test power supply, current-limiting reactor, regulating resistor, intermediate test transformer and fault simulation device without using direct destructive short circuit method, effectively reducing test risk and improving test safety.

[0088] (2) The short-circuit current parameters can be precisely controlled, and the test results are more in line with the standard requirements.

[0089] By adjusting the impedance of the test circuit using a current-limiting reactor and an adjusting resistor, this disclosure enables precise control of the effective value, peak value, and duration of the short-circuit current, ensuring that the test conditions meet the parameter requirements for short-circuit withstand tests in relevant national and industry standards, thereby improving the accuracy and authority of the test results.

[0090] (3) It can comprehensively evaluate the multiple safety performances of isolation transformers under short-circuit impact.

[0091] This disclosure allows for the simultaneous acquisition of data such as voltage drop, current surge, and temperature rise during a short circuit on the same test platform. This not only verifies the heat resistance of the isolation transformer but also reflects its mechanical stability under short-circuit electrodynamic forces, thereby enabling a comprehensive assessment of the overall safety performance of the isolation transformer.

[0092] (4) The test process is highly repeatable and is suitable for routine tests and type tests.

[0093] Since all key parameters in the test platform can be set through the equipment adjustment and control system, this disclosure can repeatedly construct the same test conditions in different test batches, avoiding the problem of traditional direct short-circuit tests relying on operational experience, and is suitable for promotion and application in laboratories or testing institutions.

[0094] (5) Effectively avoids irreversible damage to the isolation transformer under test.

[0095] By implementing graded control and current limiting protection measures for the intermediate test transformer, the short-circuit test strength requirements are met while avoiding excessive impact on the transformer body caused by uncontrolled short-circuit current, thus improving the controllability of the test process and the safety of the equipment.

[0096] (6) The platform has strong versatility and good scalability.

[0097] This disclosure adopts a modular structural design. By adjusting the voltage level, circuit parameters and control strategy, it can be extended to safety performance tests of isolation transformers and other power transformers with different capacities and voltage levels, and has high engineering practical value.

[0098] The basic principles of this disclosure have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this disclosure are merely examples and not limitations, and should not be considered as essential features of each embodiment of this disclosure. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the scope of this disclosure to the necessity of employing the aforementioned specific details for implementation.

[0099] The block diagrams of devices, apparatuses, devices, and systems disclosed herein are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0100] Additionally, as used herein, the "or" used in a list of items beginning with "at least one" indicates a separate list, such that a list of, for example, "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not imply that the described example is preferred or better than other examples.

[0101] It should also be noted that in the systems and methods of this disclosure, the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions to this disclosure.

[0102] Various changes, substitutions, and modifications can be made to the technology described herein without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, events, means, methods, and actions described above. Currently existing or later-developed processes, machines, manufactures, events, means, methods, or actions that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Therefore, the appended claims include such processes, machines, manufactures, events, means, methods, or actions within their scope.

[0103] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features disclosed herein.

[0104] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this disclosure to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations therein.

Claims

1. A simulation test system for an isolation transformer, characterized in that, include: Test power supply, operating switch, current limiting adjustment unit, intermediate test transformer, phase selection closing switch, fault simulation device and test station; The test power supply provides electrical energy to the simulation test system; the operating switch is connected to the test power supply and controls its activation and deactivation; the current limiting adjustment unit adjusts the equivalent impedance of the test circuit to control the short-circuit current parameters; the intermediate test transformer achieves voltage level matching; the phase selection closing switch controls the trigger phase angle of the short-circuit fault; and the fault simulation device simulates secondary side short circuits or internal winding short circuits that may occur during the operation of the isolation transformer. The test station is used to install the isolation transformer to be tested.

2. The system as described in claim 1, characterized in that, The current limiting adjustment unit includes: a current limiting reactor and an adjustment resistor; The current-limiting reactor is used to limit the peak value of the short-circuit current; the regulating resistor is used to regulate the effective value of the short-circuit current.

3. The system as described in claim 1, characterized in that, Also includes: Measuring equipment; The measuring equipment includes: a current measuring device and a voltage measuring device; The current measuring device is used to collect current parameters during the simulation test; the voltage measuring device is used to collect voltage parameters during the simulation test.

4. The system as described in claim 3, characterized in that, In the case of simulating an external short circuit test, the output terminal of the test power supply is connected to the operating switch and the current limiting adjustment power supply; the output terminal of the current limiting adjustment unit is connected to the input terminal of the test station; the output terminal of the test station is connected to the primary winding of the intermediate test transformer; the test station is connected to the secondary winding of the intermediate test transformer by tapping, in order to simulate a secondary short circuit or an internal short circuit in the winding.

5. The system as described in claim 4, characterized in that, The current measuring device is connected in series between the current limiting adjustment unit and the primary winding of the intermediate test transformer to collect short-circuit current and inrush current; the voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test.

6. The system as described in claim 3, characterized in that, In the case of simulating an internal short-circuit test, the output terminal of the test power supply is connected to the operating switch and the current limiting adjustment power supply; the output terminal of the current limiting adjustment unit is connected to the primary winding of the intermediate test transformer; the secondary winding of the intermediate test transformer is connected to the input terminal of the test station through the phase selection closing tube, which is used to provide test voltage to the isolation transformer under test.

7. The system as described in claim 6, characterized in that, The current measuring device includes a first current measuring device and a second current measuring device. The first current measuring device is connected in series in the circuit between the intermediate test transformer and the test station to collect the short-circuit current and inrush current of the main test circuit. The second current measuring device is connected in series in the circuit between the test station and the fault simulation device to collect the short-circuit fault current of the fault simulation branch. The voltage measuring device is connected in parallel at the input terminal of the test station to measure the port voltage of the isolation transformer under test. The test main circuit is the main path for supplying normal power to the isolation transformer under test, generating inrush current, and providing working voltage; the fault simulation branch is the path for triggering a secondary side short circuit or an internal short circuit in the winding.

8. The system as described in claim 5, characterized in that, When the simulation test is a simulated external short circuit test, the fault simulation device is kept in the off state, and the power supply is turned on by controlling the operation switch to put the isolation transformer under test into operation under no-load conditions. The voltage measuring device and the current measuring device collect voltage and current data in real time at the instant the operating switch is closed, which are used to determine the inrush current characteristics of the isolation transformer under test and obtain the first simulated test result of the isolation transformer under test.

9. The system as described in claim 7, characterized in that, In the case of simulating an internal short circuit test, the phase-selective closing switch is controlled to close at a preset phase angle. The normally open node of the even-numbered fault simulation device is closed, forming a short-circuit fault at a preset location; A short-circuit current is applied to the isolation transformer under test to simulate the dynamic process of a short-circuit fault under actual operating conditions, and a short-circuit test is performed on the isolation transformer under test to obtain a second simulation test result.

10. The system as described in claim 8 or 9, characterized in that, Also includes: Data analysis module; The device is used to acquire the short-circuit current and short-circuit voltage collected by the voltage measuring device and the current measuring device, and to process the short-circuit current and short-circuit voltage to obtain a first simulation test result or a second simulation test result.

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