Transformer current rising experiment method

Abstract

The invention discloses a transformer current rising experiment method, which comprises the following steps of forming an experiment transformer through parallel compensation of a capacitor and a transformer, and providing capacitor current response for the experiment transformer by using the capacitor; constructing an equivalent inductance model and an equivalent capacitance model; applying an initial current response according to a rated current response of the transformer, calculating a capacitor current response, and adding a nonlinear element to obtain a nonlinear voltage response; updating the capacitor current response based on the nonlinear voltage response to obtain an updated capacitor current response; under the condition of considering the temperature effect, updating the updated capacitor current response again based on an equivalent inductance model to obtain a final capacitor current response; performing asynchronous frequency modulation, and updating the voltage response to obtain an updated voltage response; and calculating an experiment result based on the updated voltage response. The device is suitable for the transformer current rising experiment.

Description

Technical Field

[0001] The invention relates to the technical field of north-finding and orientation-orientation, and in particular to a transformer current-raising experimental method. Background Art

[0002] In the field of power systems, especially with the continuous development of power electronics technology and the emergence of the concept of smart grids, the widespread application of high-voltage and large-capacity power electronic power conversion equipment has become a key trend. These devices include transformers, frequency converters, and converters, which play a vital role in the stability, energy efficiency, and power supply quality of power systems. However, traditional transformer and converter designs are usually suitable for low voltage and low power occasions, and it is difficult to meet the requirements of high voltage and large capacity. In addition, the transformer needs to be calibrated with load during operation to ensure the reliability of the differential protection system, but the traditional method has many problems, including high cost, energy waste, and safety risks.

[0003] With the rapid development of power electronics technology, the application scope of high-voltage and large-capacity power electronic power conversion equipment is expanding. These devices include high-voltage DC converters, high-voltage inverters and high-voltage converters, which are used to realize key functions such as DC transmission, power conversion and voltage regulation of power systems. The introduction of power electronics technology enables power systems to respond to different power demands more flexibly and improves the efficiency and reliability of power systems.

[0004] The voltage level and current level of traditional transformers are limited by the power devices themselves. Therefore, they are difficult to meet the power needs of high voltage and large capacity. In order to realize high voltage and large capacity transformers, expensive materials and a large amount of insulation are usually required. This leads to high cost manufacturing and maintenance. Due to the increase in voltage level, the energy loss of traditional transformers under high voltage conditions also increases, resulting in reduced energy efficiency. Under high voltage conditions, the insulation materials and insulation systems of traditional transformers are susceptible to problems such as voltage breakdown and electric shock, reducing the reliability of the equipment.

[0005] Therefore, it is necessary to conduct current boosting experiments on high-voltage and large-capacity power electronic power conversion equipment, but traditional current boosting experiments generally require large test power supplies, step-up and current boosting transformers, voltage regulators and other expensive and energy-intensive equipment, which makes the test cost very high. Summary of the invention

[0006] In order to solve the above technical problems, the object of the present invention is to provide a transformer current boosting test method.

[0007] A first aspect of the present invention provides a transformer current boosting test method, comprising the following steps:

[0008] S1: A capacitor is connected in parallel with the transformer to form an experimental transformer, and the capacitor is used to provide a capacitor current response for the experimental transformer, wherein the transformer is the first equivalent inductor and the experimental transformer is the second equivalent inductor; and an equivalent inductance model is constructed according to the operating frequency, number of turns, core resistance, leakage inductance resistance, and maximum current response of the transformer; and an equivalent capacitance model is constructed according to the total impedance of the transformer and the operating frequency of the transformer;

[0009] S2: Apply an initial current response based on the rated current response of the transformer, calculate the capacitor current response, and add nonlinear elements to obtain a nonlinear voltage response;

[0010] S3: updating the capacitor current response based on the nonlinear voltage response to obtain an updated capacitor current response; then, considering the temperature effect, based on the equivalent inductance model, updating the updated capacitor current response again to obtain a final capacitor current response;

[0011] S4: performing asynchronous frequency modulation, updating the voltage response, and obtaining an updated voltage response; and calculating the experimental results based on the updated voltage response.

[0012] Preferably, in step S1, the constructed equivalent inductance model is expressed using the following formula:

[0013]

[0014] Where f1 is the operating frequency of the transformer; M turns is the number of turns of the transformer; R core is the core resistance; L leakage is the leakage inductance; I max is the maximum current response of the transformer; L eq1 represents the equivalent inductance;

[0015] The constructed equivalent capacitance model is expressed using the following formula:

[0016]

[0017] Among them, Z system is the total impedance of the transformer; C eq1 represents the equivalent capacitance; max(α, γ) means taking the maximum value in the impedance nonlinear parameter a and the frequency dependence parameter γ.

[0018] Preferably, in step S2, the applied initial current response is expressed using the following formula:

[0019]

[0020] Among them, I ratdis the rated current response of the transformer; t represents time; τ is the time constant, which controls the rate of exponential decay; is an exponential decay term, indicating that the initial current response decays exponentially with time; V phase represents the phase voltage in response to the applied current; θ is the phase of the phase voltage; Indicates the conversion of phase voltage to line voltage.

[0021] Preferably, in step S2, the capacitor current response is calculated using the following formula:

[0022]

[0023] in, Indicates the capacitor voltage V C1 The derivative with respect to time gives the rate of change of the current response; Indicates the ripple value of the capacitor voltage V ripple Convert to effective value; R ESR represents the equivalent series resistance of the capacitor; f switch Indicates the frequency of power switching.

[0024] Preferably, in step S2, the following formula is used to express the nonlinear voltage response obtained by adding the nonlinear element:

[0025]

[0026] Among them, f nonlinear Indicates the frequency of nonlinear effects; sin(2π·f nonlinear ·t) represents the sinusoidal function term, simulating the sinusoidal response of nonlinear elements; is the scaling factor used to adjust the amplitude of the sine function; I nonlinear represents the current response of the nonlinear element; represents the Gaussian distribution function, which is used to simulate the exponential response of nonlinear elements. σ controls the standard deviation of the Gaussian distribution and affects the shape of the exponential response of the nonlinear element.

[0027] Preferably, in step S3, the capacitor current response is updated using the following formula:

[0028]

[0029] Among them, I C2 is the updated capacitor current response, V nl is the voltage response of the nonlinear element.

[0030] Preferably, in step S3, the environmental resistance is calculated using the following formula while taking the temperature effect into consideration:

[0031]

[0032] Among them, R thermal is the ambient resistance; β is the temperature coefficient, which indicates the ratio of resistance change with temperature; ΔT is the ambient temperature change value; K indicates the sensitivity of resistance to temperature change; λ is the thermal compensation parameter; S is the temperature adjustment coefficient.

[0033] Preferably, in step S3, the updated capacitor current response is updated again using the following formula to obtain a final capacitor current response:

[0034]

[0035] Among them, I C3 is the final capacitor current response; V offset is the offset voltage of the capacitor; ρ is the offset adjustment coefficient.

[0036] Preferably, in step S4, asynchronous frequency modulation is performed using the following formula to obtain an updated voltage response:

[0037] f sync =f carrier +δf·(sin(2π·f modulation ·t)+cos(2π·f nonlinear t));

[0038] Among them, f carrier is the carrier frequency of the asynchronous frequency modulation; δf is the asynchronous frequency modulation coefficient; f modulation is the frequency of the asynchronous frequency modulation;

[0039] The updated voltage response is obtained using the following formula:

[0040]

[0041] Among them, V C3 is the updated voltage.

[0042] Preferably, in step S4, the experimental result is calculated based on the updated voltage response using the following formula:

[0043]

[0044] Among them, Result is the experimental result; t0 is the starting time of the experiment; t end End the experiment for the experiment.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] 1. The present invention is applicable to current-increasing experiments of high-voltage and large-capacity power electronic power conversion equipment, providing an efficient and feasible approach for the design, testing and verification of these equipment. Traditional transformers are usually suitable for low voltage and low power applications, while the method of the present invention allows engineers to simulate current response under high voltage conditions, ensuring the performance and reliability of the equipment in high voltage environments.

[0047] 2. In the projects of 500kV and above substations and converter stations, when there is no load on one side of the transformer, the method of the present invention allows for load calibration of the current rise, solving the problems of high power demand, heavy equipment weight, energy waste and safety risks in the traditional method. The reliability of differential protection is improved, which helps to avoid potential power grid accidents.

[0048] 3. Compared with the traditional method, the method of the present invention does not require expensive and energy-intensive equipment such as large test power supplies, step-up and current-increasing transformers and voltage regulators, which reduces the cost of the test, reduces energy waste, and also reduces the maintenance and transportation costs of the equipment.

[0049] 4. By calculating the initial current response and introducing nonlinear elements, the method of the present invention is closer to actual working conditions, which helps engineers evaluate the performance of equipment under complex circuit conditions. The introduction of nonlinear elements allows engineers to simulate potential problems in the circuit, thereby better diagnosing and debugging problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a principle flow chart of the present invention. DETAILED DESCRIPTION

[0051] The following is a clear and complete description of the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0052] Embodiment 1: A transformer current boosting test method, comprising the following steps:

[0053] Step 1: First, a capacitor is connected in parallel with the transformer to form an experimental transformer, and the capacitor is used to provide a capacitor current response for the experimental transformer, wherein the transformer is the first equivalent inductor and the experimental transformer is the second equivalent inductor; and an equivalent inductance model is constructed according to the operating frequency, number of turns, core resistance, leakage inductance resistance, and maximum current response of the transformer; and an equivalent capacitance model is constructed according to the total impedance of the transformer and the operating frequency of the transformer;

[0054] The capacitor is connected in parallel with the transformer to form an experimental transformer. The purpose of this is to provide the current response of the experimental transformer through the capacitor. The capacitor has the characteristics of storing and releasing charge, which can introduce dynamic response in the system and make the experiment more flexible. The transformer can be regarded as an inductor in the circuit. By considering factors such as the operating frequency, number of turns, core resistance, leakage inductance resistance, and maximum current response of the transformer, an equivalent inductance model is constructed. This model describes the inductance characteristics of the transformer and is an abstraction of the actual transformer behavior. At the same time, by considering the total impedance and operating frequency of the transformer, an equivalent capacitance model is constructed. This model is used to describe the capacitance characteristics of the transformer, that is, the capacitance response of the transformer when the current changes. The comprehensive consideration of the inductance and capacitance models, combined with the specific parameters of the transformer, makes the model more accurate and close to reality. By constructing these equivalent models, the behavior of the experimental transformer can be better simulated, providing a more accurate basis for subsequent experiments.

[0055] After the capacitor is connected in parallel with the transformer for compensation, the behavior of the experimental transformer can be more accurately simulated through the equivalent inductance model and the equivalent capacitance model. This means that capacitors can be used in experiments to simulate the inductance and capacitance characteristics of the transformer in order to better understand and evaluate the performance of the transformer. By connecting in parallel with the capacitor, the experimental transformer can obtain a capacitor current response. This current response is the basis for calculations and analysis in subsequent steps, and it contains information about the interaction between the capacitor and the transformer. Constructing equivalent inductance and capacitance models helps to establish a basic model for the experiment, which can be used for calculations and analysis in subsequent steps. By incorporating the parameters of the transformer into the equivalent inductance model and the equivalent capacitance model, the behavior of the circuit can be described more accurately, rather than just using idealized components.

[0056] Step 2: Apply an initial current response based on the rated current response of the transformer, calculate the capacitor current response, and add nonlinear elements to obtain a nonlinear voltage response;

[0057] First, an initial current response is applied based on the rated current response of the transformer. This is to simulate the current changes when the transformer starts under actual operating conditions. By applying the initial current response, the initial conditions in the system can be introduced, making the experiment more realistic. After applying the initial current response, the current response of the capacitor is calculated. This step involves modeling and calculating the current of the capacitor, taking into account the response time and current changes of the capacitor. This enables the real-time status of the capacitor to be tracked, providing basic data for subsequent steps. Next, nonlinear elements are introduced. These elements may include diodes, transistors, etc., which have nonlinear current-voltage characteristics. These nonlinear elements are introduced to more accurately simulate the nonlinear response of the actual transformer under different operating conditions. This is an innovation of the method because it takes into account the nonlinear characteristics that may exist in the actual system and improves the simulation accuracy of the experiment. By introducing nonlinear elements, a nonlinear voltage response can be obtained. This is the feedback of the system to the initial current response, which includes the influence of nonlinear elements. This voltage response is a key output of the experiment and reflects the nonlinear behavior that may occur in the actual system. The introduction of nonlinear elements takes into account the nonlinear responses that may exist in the actual system. By introducing nonlinear characteristics in the initial stage, the method more comprehensively simulates the actual behavior of the transformer and improves the fidelity and reliability of the experimental method.

[0058] Step 3: updating the capacitor current response based on the nonlinear voltage response to obtain an updated capacitor current response; then, considering the temperature effect, based on the equivalent inductance model, updating the updated capacitor current response again to obtain a final capacitor current response;

[0059] First, the current response of the capacitor is updated based on the nonlinear voltage response. This is done by feeding back the voltage changes in the system to the capacitor model so that the current response is adjusted. The nonlinear voltage response contains the actual response of the system after the nonlinear element is introduced. After updating the capacitor current response, the temperature effect is considered. Temperature has a significant impact on the performance of electrical components, especially for high-load equipment such as transformers. By considering the temperature effect, the impact of the actual working environment on the system can be more realistically simulated. With the temperature effect considered, the current response of the capacitor is updated again based on the equivalent inductance model. The equivalent inductance model is used to describe the response of the inductance component under changing conditions, and the update after considering the temperature effect is more in line with the actual transformer working conditions. The nonlinear voltage response and temperature effect are comprehensively considered. By adjusting the capacitor current response based on the actual feedback and performing a second update with the temperature effect considered, this method more comprehensively simulates the dynamic behavior of the transformer under actual working conditions. This comprehensive consideration of different factors improves the creativity and authenticity of the experimental method and makes the experimental results more reliable.

[0060] Step 4: Perform asynchronous frequency modulation, update the voltage response, and obtain an updated voltage response; based on the updated voltage response, calculate the experimental results. In this step, asynchronous frequency modulation is performed, that is, the operating frequency of the experimental system is changed. Asynchronous frequency modulation allows the simulation of frequency changes in actual working conditions, which is crucial for the response of equipment such as transformers under different working conditions. As the frequency changes, the voltage response will be updated accordingly. This is achieved by adjusting the frequency of the system and considering factors such as nonlinear voltage response, thereby reflecting the dynamic response of the actual system when the frequency changes. Finally, based on the updated voltage response, the experimental results are calculated. This may involve measuring parameters such as current, power, and voltage to derive an assessment of the performance of the transformer. The purpose of this step is to obtain quantitative data from the experiment for analyzing and comparing the performance of the system under different working conditions. Asynchronous frequency modulation is introduced to more comprehensively simulate the frequency changes under actual working conditions. In addition, by calculating the experimental results based on the updated voltage response, this method provides a quantitative assessment of the performance of the transformer, making the experiment more operational and practical.

[0061] Embodiment 2: In step 1, the equivalent inductance model constructed is expressed using the following formula:

[0062]

[0063] Where f1 is the operating frequency of the transformer; M turns is the number of turns of the transformer; R core is the core resistance; L leakage is the leakage inductance; I max is the maximum current response of the transformer; L eq1 Represents the equivalent inductance; in step 1, the equivalent capacitance model constructed is expressed using the following formula:

[0064]

[0065] Among them, Z system is the total impedance of the transformer; C eq1 represents the equivalent capacitance; max(α, γ) means taking the maximum value in the impedance nonlinear parameter α and the frequency dependence parameter γ.

[0066] Specifically, this model is used to simulate the inductance characteristics of the transformer, which is a key parameter in the transformer and affects its electrical performance. The effect of operating frequency and number of turns on inductance is considered. As the frequency increases or the number of turns increases, the value of the inductance increases accordingly. The second part of the model The influence of core resistance, leakage inductance and maximum current response on the inductance are considered. The ratio between core resistance and leakage inductance describes the characteristics of the current distribution inside the transformer, while It represents the response of current at different frequencies. By taking these factors into consideration, the equivalent inductance model allows for a more accurate simulation of the inductance characteristics of the transformer, thereby helping engineers to better understand and analyze the performance of the transformer. Inductance is a component in a circuit. Its basic principle is that according to Faraday's law of electromagnetic induction, electromagnetic induction is generated when current passes through, resulting in a change in voltage. The voltage response of the inductor is proportional to the rate of change of the current, usually expressed as Where L is the inductance of the inductor. According to the principles of electromagnetics, inductance is related to the rate of change and frequency of current. When the current frequency increases, the inductance of the inductor will also increase. This is the basic characteristic of the inductor property.

[0067] In the equivalent inductor model, the first part of the equation Considering the operating frequency f1 and the number of turns M turns For inductance L eq1 In actual transformers, the core usually has a certain resistance R core , and the leakage inductance L leakage describes the current flowing around the core. The second part of the formula Taking into account the core resistance, leakage inductance and maximum current response I max For inductance L eq1 The ratio between the core resistance and the leakage inductance It reflects the distribution of current between the core and leakage inductance, which has an important impact on the inductance value. Based on the above principles, the role of the equivalent inductance model is to allow engineers to more accurately estimate the inductance characteristics of the transformer at different operating frequencies. Through the model, the combined effects of factors such as the frequency dependence, number of turns, core resistance, leakage inductance, etc. of the transformer on the inductance can be considered, so as to better understand and analyze the performance of the transformer. This helps power system engineers better consider the behavior of the transformer when designing and operating the power system to ensure the stability and efficiency of the system.

[0068] A capacitor is a circuit element that can store charge and store electrical energy. The relationship between the voltage V of a capacitor and the charge Q stored in it is given by the equation for capacitance. Description, where C is the capacitance of the capacitor. In an AC circuit, the impedance of the capacitor is Z C It is a parameter that describes the degree of resistance of capacitance to current. The relationship between it, capacitance C and frequency f is expressed by the following formula: This formula shows that the impedance of a capacitor is inversely proportional to the frequency. In other words, as the frequency increases, the impedance of the capacitor decreases and the capacitor becomes less of a barrier to the flow of current. The formula for the equivalent capacitor model is The relationship between capacitance and frequency and the influence of the total system impedance are taken into account. The total impedance z of the system system and frequency f1, and takes into account the nonlinearity and frequency dependence of the impedance. This denominator represents the impedance of the capacitor. The purpose of this model is to simulate the characteristics of the capacitor in the transformer system and help engineers understand the behavior of the capacitor at different frequencies. By considering factors such as operating frequency, total impedance, and nonlinearity and frequency dependence of impedance, this model provides a more accurate simulation of the capacitor, which helps to optimize the design and analysis of power systems. This model can be used to study the stability of the transformer system, the response frequency changes, and the impact of the capacitor in the system to better manage the performance of the power system.

[0069] Example 3: The initial current response applied in step 2 is expressed using the following formula:

[0070]

[0071] Among them, I rated is the rated current response of the transformer; t represents time; τ is the time constant, which controls the rate of exponential decay; is an exponential decay term, indicating that the initial current response decays exponentially with time; V phase represents the phase voltage in response to the applied current; θ is the phase of the phase voltage; Indicates the conversion of phase voltage to line voltage.

[0072] Specifically, the exponential decay term Principle: This term represents the initial current response decaying exponentially over time. Exponential decay is common in circuits, and it represents a process where a starting value gradually decreases to zero. The time constant τ controls the rate of decay, with smaller τ values ​​indicating faster decay and larger τ values ​​indicating slower decay. Principle: This part is used to convert the phase voltage V phase In a three-phase power system, the line voltage is usually times, which is due to the phase difference between the phase voltages. The phase difference is taken into account and the effect of the phase voltage is converted to the line voltage. The main function of the formula is to describe the change of the initial current response over time and the effect of converting the phase voltage to the line voltage. This is very important for analyzing the dynamic response of the transformer, especially in fault conditions in power systems, and in transformer protection and control. By controlling the time constant τ, the decay rate of the current response can be simulated, which is crucial to understanding the change and stability of the current in the transformer.

[0073] Example 4: In step 2, the capacitor current response is calculated using the following formula:

[0074]

[0075] in, Indicates the capacitor voltage V C1 The derivative with respect to time gives the rate of change of the current response; Indicates the ripple value of the capacitor voltage V ripple Convert to effective value; R ESR represents the equivalent series resistance of the capacitor; f switch Indicates the frequency of power switching.

[0076] Specifically, Principle: Indicates the capacitor voltage V C1 The time derivative is the rate of change of voltage over time. In a circuit, current is the time derivative of voltage, which means that the current is a result of the rate of change of voltage. This term describes the rate of change of the current response, which is related to the change in the capacitor voltage. Principle: This part is used to convert the ripple value of the capacitor voltage V ripple Convert to RMS value. In a circuit, ripple is a periodic variation in voltage or current, usually caused by an AC power source. Set the ripple value V ripple Converted to effective value, where R ESR Represents the equivalent series resistance of the capacitor. This is to take into account the effect of ripple on current. Principle: This term involves the capacitor voltage and the power switching frequency f svitch . It represents the relationship between the capacitor voltage and the switching frequency, using a cube root operation. This term is used to consider the effect of the power supply switching frequency on the current response. The main purpose of the formula is to calculate the current response of the capacitor to understand the behavior of the capacitor in the circuit. The first term The contribution of the rate of change of voltage to the current response is taken into account, which is very important in describing how quickly the current changes. The effect of voltage ripple on current is taken into account, especially under AC power supply. The relationship between capacitor voltage and switching frequency is considered to understand the response of the capacitor to power switching.

[0077] In the above formula, the ripple value V ripple The significance of is to consider the effect of the periodic change of capacitor voltage on the current response. This is very important in fields such as power electronics and switching power supplies, because the power supply usually provides electrical energy in the form of AC, and some components in the circuit (such as capacitors) may be very sensitive to the ripple of AC voltage. Specifically, the ripple value V rippleIt indicates the amplitude of voltage fluctuations, rather than a fixed DC voltage. When the capacitor voltage has ripple, it may affect the change of current, because the current is usually related to the rate of change of voltage. Therefore, when analyzing the circuit, it is important to consider the ripple value of the capacitor voltage to ensure the performance and stability of the circuit.

[0078] Example 5: In step 2, the following formula is used to express the nonlinear voltage response obtained by adding a nonlinear element:

[0079]

[0080] Among them, f nonlinear Indicates the frequency of nonlinear effects; sin(2π·f nonlinear ·t) represents the sinusoidal function term, simulating the sinusoidal response of nonlinear elements; is the scaling factor used to adjust the amplitude of the sine function; I nonlinear represents the current response of the nonlinear element; represents the Gaussian distribution function, which is used to simulate the exponential response of nonlinear elements. σ controls the standard deviation of the Gaussian distribution and affects the shape of the exponential response of the nonlinear element.

[0081] Specifically, the sinusoidal response part: The sinusoidal response part is composed of This part models the response of nonlinear components to periodic signals. Sine functions are very common in electronic circuits because they can describe the characteristics of alternating current signals.

[0082] f nonlinear represents the response frequency of the nonlinear element, so this part of the formula allows the simulation of the response of the nonlinear element to signals of different frequencies. Exponential response part: The exponential response part is composed of This part simulates the exponential voltage response of nonlinear components. Exponential decay is a very common response form, which usually appears in the saturation and nonlinear regions of components. nonlinear represents the magnitude of the exponential response of the nonlinear element, while σ controls the shape of the response, i.e. it affects the width and sharpness of the response. Used to adjust the amplitude of the sinusoidal response to match the exponential response. Sinusoidal and exponential responses usually have different amplitude ranges, and by using a scaling factor, they can be balanced to ensure that they appear in the voltage response in the appropriate proportion. The main role of this formula is to simulate the voltage response of nonlinear elements, especially when the nonlinear element has a complex response to the input signal. The sinusoidal response part is used to consider the response of nonlinear elements to periodic signals, which is very common in fields such as wireless communications and radio frequency electronics. The exponential response part is used to consider the behavior of nonlinear elements in the nonlinear region, which is very useful for simulating phenomena such as nonlinear distortion and nonlinear saturation. In summary, the form of this formula is based on the characteristics and response mechanism of nonlinear elements in electronic circuits. It allows engineers to better understand and simulate the behavior of nonlinear elements in circuits for circuit design, analysis, and performance evaluation. Different components may have different response characteristics, so the form of this formula can be adjusted and adapted according to the specific nonlinear element.

[0083] Example 6: In step 3, the capacitor current response is updated using the following formula:

[0084]

[0085] Among them, I C2 is the updated capacitor current response.

[0086] Specifically, 1. Original current response part I C1 :I C1 Represents the original current response of the capacitor, usually in the initial state of the circuit or obtained in a previous calculation. This part reflects the current response of the capacitor when it is not affected by nonlinear components. Updated Current Response Section: The Updated Current Response Section consists of α is a coefficient used to adjust the amplitude of the updated current response. This coefficient can be used to control the degree of influence of nonlinear components on the current response. nl represents the voltage response of the nonlinear element, which is the nonlinear voltage response obtained in the previous calculation. This part is used to consider the direct effect of the nonlinear element on the current. γ is another coefficient that affects the adjustment speed of the current response. A larger γ value means a faster response, and a smaller γ value means a slower response. is a radical that is used to account for the frequency dependence of the voltage response and nonlinear components. This term can be used to adjust the current response to account for the frequency dependence. The main purpose of this formula is to model the current response of a capacitor to account for the effects of nonlinear components. Updated Current Response section It is used to represent the additional current response caused by the nonlinear element. This response is different from the voltage response V nlThe α and γ coefficients are used to control the magnitude and speed of the updated current response, while Used to account for frequency dependence. In summary, the form of this formula is based on the relationship between the current response of the capacitor and the voltage response of the nonlinear element, adjusted by some coefficients to update the current response to account for the effects of the nonlinear element. This helps engineers better understand and simulate the behavior of the circuit, especially when the nonlinear element plays a key role in the circuit. The choice of coefficients can be adjusted according to the specific circuit and nonlinear element to meet the design and performance requirements.

[0087] Embodiment 7: In step 3, the environmental resistance is calculated using the following formula while considering the temperature effect:

[0088]

[0089] Among them, R thermal is the ambient resistance; β is the temperature coefficient, which indicates the ratio of resistance change with temperature; ΔT is the ambient temperature change value; K indicates the sensitivity of resistance to temperature change; λ is the thermal compensation parameter; S is the temperature adjustment coefficient.

[0090] Specifically, temperature coefficient β: The temperature coefficient β indicates the proportion of resistance change with temperature. This is determined based on the material properties of the resistor element and the temperature characteristic curve. According to the properties of the resistor material, an increase or decrease in temperature will cause a change in the resistance value. The specific proportion of the change is controlled by β. Temperature sensitivity K: The temperature sensitivity K indicates how sensitive the resistor is to temperature changes. This parameter also depends on the properties of the resistor material. Some resistor materials are more sensitive to temperature changes and their resistance values ​​will change faster, while others may be relatively insensitive. Thermal compensation parameter λ: The thermal compensation parameter λ is used to adjust the response of the resistance value to better match the actual temperature effect. Different resistor elements or materials may have different temperature response curves, and λ can be used to correct them to suit specific situations. Temperature adjustment coefficient S: The temperature adjustment coefficient S affects the shape of the temperature effect, especially in nonlinear situations. It is usually related to the characteristics of the resistor element. Some resistor elements may show different responses in different ranges of temperature changes, and S can be used to adjust the shape of this response. The main function of this formula is to calculate the actual value of the resistor at different temperatures to take into account the change of the resistance value with the ambient temperature. The temperature coefficient β and temperature sensitivity K describe how the resistance value responds to temperature changes, and they are based on the thermal characteristics of the resistor material. The thermal compensation parameter λ and the temperature adjustment factor S are used to more accurately describe the temperature dependence of the resistor value, especially in the case of nonlinearity.

[0091] Embodiment 8: In step 3, the updated capacitor current response is updated again using the following formula to obtain the final capacitor current response:

[0092]

[0093] Among them, I C3 is the final capacitor current response; V offset is the offset voltage of the capacitor; ρ is the offset adjustment coefficient.

[0094] Specifically, the final capacitor current response part I C3 The science of the offset voltage section: This section represents the final capacitor current response, which is the final result of the current, taking into account all influencing factors. The current response of the capacitor depends on factors such as voltage, resistance, inductance, etc., and this formula takes into account the effects of additional offset voltage and adjustment factors. The science of the offset voltage section: The offset voltage V offset is the static voltage on the capacitor, usually caused by the bias circuit or other factors in the circuit. This voltage will generate a static electric field on the capacitor, resulting in uneven charge distribution, which in turn affects the current response of the capacitor. This may be a nonlinear effect, where ρ is the offset adjustment factor that adjusts for the effect of the offset voltage. This means that the effect of the offset voltage may not be linear with the current response. This formula is designed based on the relationship between the current response and voltage of the capacitor, while taking into account the nonlinear offset voltage effect. The current response of a capacitor is the derivative of the capacitor voltage over time, and is also affected by other components in the circuit. The introduction of the offset voltage takes into account the static electric field effect of the capacitor, which may cause nonlinear behavior in the current response. By using Adjustment can better simulate this nonlinear effect.

[0095] Embodiment 9: In step 4, the following formula is used to perform asynchronous frequency modulation to obtain an updated voltage response:

[0096] f sync =f carrier +δf·(sin(2π·f modulation ·t)+cos(2π·f nonlinear t));

[0097] Among them, f carrier is the carrier frequency of the asynchronous frequency modulation; δf is the asynchronous frequency modulation coefficient; f modulation is the non-synchronous frequency modulation frequency; using the following formula, the updated voltage response is obtained:

[0098]

[0099] Among them, V C3 is the updated voltage.

[0100] Specifically, the asynchronous frequency modulation part f sync :f sync Indicates the signal frequency after asynchronous frequency modulation. This part is obtained by carrier With asynchronous frequency modulation parameters δf and f modulation Combined to simulate the effect of asynchronous frequency modulation. Update the voltage response section V C3 :V C3 represents the updated voltage response, that is, the voltage signal after considering the effects of asynchronous frequency modulation and other circuit elements. This part is calculated by taking the total system impedance Z system 、Environmental resistance R thermal , core resistance R core , the equivalent series resistance R of the capacitor ESR The current response of the capacitor I C3 The main function of this formula is to simulate the voltage response after asynchronous frequency modulation, taking into account the current response of the capacitor, the total impedance of the system, and the influence of other components. The purpose of asynchronous frequency modulation is to introduce frequency changes in the signal to simulate the nonlinear effects in the circuit. The updated voltage response part takes into account the frequency response and nonlinear effects of the current response, and the exponential term and radical terms To adjust the voltage response. In summary, the form of this formula is based on the relationship between asynchronous frequency modulation and circuit elements. It is used to simulate the behavior of capacitors in nonlinear circuits, taking into account the effects of frequency modulation and current response. This helps engineers better understand the behavior of circuits, especially when nonlinear effects and frequency changes need to be considered. The selection of various parameters and terms in the formula usually needs to be adjusted according to the specific circuit and application.

[0101] Example 10: In step 4, the following formula is used to calculate the experimental results based on the updated voltage response:

[0102]

[0103] Among them, Result is the experimental result; t0 is the starting time of the experiment; t end End the experiment for the experiment.

[0104] Specifically, the experimental result part Result: Result represents the result of the experiment. It is a numerical value used to measure a certain performance or indicator in the experiment. This part is obtained by integrating the voltage response and nonlinear voltage response. Voltage response integration part: represents the integral part of the voltage response. This part first calculates the voltage response v C3Divide by the absolute value of the total system impedance and other circuit elements, and then perform an analysis of the time from t0 to t end The time integral of . This integral can be used to evaluate the oscillations and changes in the capacitor voltage response during the entire experiment. Nonlinear voltage response integral part: Represents the integral part of the nonlinear voltage response. This part is the integral part of the nonlinear voltage response From t0 to t end The time integral of the voltage response is used to account for voltage fluctuations caused by nonlinear elements in the circuit. The main purpose of this formula is to calculate experimental results to evaluate the performance or response of a circuit over a period of time. The voltage response integral is used to account for oscillations and changes in the capacitor voltage response to evaluate the stability of the circuit. The nonlinear voltage response integral is used to account for voltage fluctuations caused by nonlinear elements in the circuit to evaluate the nonlinear characteristics of the circuit.

[0105] The main purpose of the present invention is to provide a transformer current increase experimental method, which is intended to simulate and evaluate the current response of the transformer under different working conditions. The method is intended to help engineers understand the performance of the transformer more comprehensively, especially when nonlinear effects and temperature changes are taken into account. The core function of the method is to simulate the current response of the transformer. By applying an initial current response and taking into account various factors, such as nonlinear elements, temperature effects, and asynchronous frequency modulation, it is able to accurately simulate the response of the transformer to current changes in actual work. The present invention takes into account nonlinear elements and nonlinear effects in the circuit. This is very important for analyzing the current response in nonlinear circuits, because in actual applications, the components in the circuit usually exhibit nonlinear behavior. The method also takes into account temperature effects, including the thermal effects of capacitors and ambient temperature changes. This allows engineers to more realistically evaluate the performance of the transformer under different temperature conditions. By calculating the experimental results, the present invention allows engineers to evaluate the performance of the circuit under different working conditions, including the voltage response of the capacitor, nonlinear effects, and the influence of temperature changes. The present invention is achieved through a series of steps, which include constructing equivalent inductance and equivalent capacitance models, applying an initial current response, updating the capacitor current response, performing asynchronous frequency modulation, and calculating experimental results. These steps combine circuit theory, nonlinear circuit models, and consideration of temperature effects to achieve simulation and evaluation of transformer current ramp-up experiments. This approach helps engineers gain a more comprehensive understanding of the behavior of transformer circuits, thereby optimizing circuit design and ensuring the reliability and stability of their performance.

[0106] The present invention provides a transformer current increase test method suitable for high voltage and large capacity occasions. By constructing equivalent inductance and equivalent capacitance models, the method can simulate and evaluate the current response of high voltage and large capacity power electronic power conversion. This helps to ensure the performance and stability of these power electronic devices under high voltage environments. In the new construction and expansion projects of 500kV and above substations and converter stations, when there is no load on one side of the transformer, it is difficult to perform differential protection verification with load using traditional methods. The method of the present invention allows the simulation of the current response of the transformer, and the current increase experiment can be performed even if there is no load on one side, thereby solving the problem of differential protection verification. The traditional method requires large test power supplies, step-up and current increase transformers, voltage regulators and other equipment, which are heavy and require a large amount of energy supply. In contrast, the method of the present invention adopts simulation and calculation methods, does not require large test equipment, and greatly reduces the equipment and energy costs required for the test. The method of the present invention can perform modular debugging and system verification, which helps to discover potential problems and hidden dangers in the circuit. Through the calculation and analysis of the experimental results, engineers can have a more comprehensive understanding of the performance of the circuit, thereby diagnosing and repairing problems.

[0107] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A transformer current boosting test method, characterized in that: The following steps are involved: S1: A capacitor is connected in parallel with the transformer to form an experimental transformer, and the capacitor is used to provide a capacitor current response for the experimental transformer, wherein the transformer is the first equivalent inductor and the experimental transformer is the second equivalent inductor; and an equivalent inductance model is constructed according to the operating frequency, number of turns, core resistance, leakage inductance resistance, and maximum current response of the transformer; and an equivalent capacitance model is constructed according to the total impedance of the transformer and the operating frequency of the transformer; S2: Apply an initial current response based on the rated current response of the transformer, calculate the capacitor current response, and add nonlinear elements to obtain a nonlinear voltage response; S3: updating the capacitor current response based on the nonlinear voltage response to obtain an updated capacitor current response; then, considering the temperature effect, based on the equivalent inductance model, updating the updated capacitor current response again to obtain a final capacitor current response; S4: performing asynchronous frequency modulation, updating the voltage response, and obtaining an updated voltage response; and calculating the experimental results based on the updated voltage response.

2. A transformer current increase test method according to claim 1, characterized in that: In step S1, the constructed equivalent inductance model is expressed using the following formula: Where f1 is the operating frequency of the transformer; M turns is the number of turns of the transformer; R core is the core resistance; L leakage is the leakage inductance; I max is the maximum current response of the transformer; L eq1 represents the equivalent inductance; The constructed equivalent capacitance model is expressed using the following formula: Among them, Z system is the total impedance of the transformer; C eq1 represents the equivalent capacitance; max(α, γ) means taking the maximum value in the impedance nonlinear parameter α and the frequency dependence parameter γ.

3. A transformer current boosting test method according to claim 2, characterized in that: In step S2, the applied initial current response is expressed using the following formula: Among them, I rated is the rated current response of the transformer; t represents time; τ is the time constant, Control the rate of exponential decay; is an exponential decay term, indicating that the initial current response decays exponentially with time; V phase represents the phase voltage in response to the applied current; θ is the phase of the phase voltage; Indicates the conversion of phase voltage to line voltage.

4. A transformer current boosting test method according to claim 3, characterized in that: In step S2, the capacitor current response is calculated using the following formula: in, Indicates the capacitor voltage V C1 The derivative with respect to time gives the rate of change of the current response; Indicates the ripple value of the capacitor voltage V ripple Convert to effective value; R ESR represents the equivalent series resistance of the capacitor; f switch Indicates the frequency of power switching.

5. A transformer current boosting test method according to claim 4, characterized in that: In step S2, the following formula is used to express the nonlinear voltage response obtained by adding the nonlinear element: Among them, f nonlinear Indicates the frequency of nonlinear effects; sin(2π·f nonlinear ·t) represents the sinusoidal function term, simulating the sinusoidal response of nonlinear elements; is the scaling factor used to adjust the amplitude of the sine function; I nonlinear represents the current response of the nonlinear element; represents the Gaussian distribution function, which is used to simulate the exponential response of nonlinear elements. σ controls the standard deviation of the Gaussian distribution and affects the shape of the exponential response of the nonlinear element.

6. A transformer current boosting test method according to claim 5, characterized in that: Step S3, update the capacitor current response using the following formula: Where IC2 is the updated capacitor current response, V nl is the voltage response of the nonlinear element.

7. A transformer current boosting test method according to claim 6, characterized in that: In step S3, the environmental resistance is calculated using the following formula while taking the temperature effect into account: Among them, R themal is the ambient resistance; β is the temperature coefficient, which indicates the ratio of resistance change with temperature; ΔT is the ambient temperature change value; K indicates the sensitivity of resistance to temperature change; λ is the thermal compensation parameter; S is the temperature adjustment coefficient.

8. A transformer current boosting test method according to claim 7, characterized in that: In step S3, the updated capacitor current response is updated again using the following formula to obtain the final capacitor current response: Among them, I C3 is the final capacitor current response; V offset is the offset voltage of the capacitor; ρ is the offset adjustment coefficient.

9. A transformer current boosting test method according to claim 8, characterized in that: In step S4, asynchronous frequency modulation is performed using the following formula to obtain an updated voltage response: f sync =f carrier +δf·(sin(2π·f modulation ·t)+cos(2π·f nonlinear ·t)); Among them, f carrier is the carrier frequency of the asynchronous frequency modulation; δf is the asynchronous frequency modulation coefficient; f modulation is the frequency of the asynchronous frequency modulation; The updated voltage response is obtained using the following formula: Among them, V C3 is the updated voltage.

10. A transformer current boosting test method according to claim 9, characterized in that: In step S4, the experimental results are calculated based on the updated voltage response using the following formula: Among them, Result is the experimental result; t0 is the starting time of the experiment; t end End the experiment for the experiment.

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