Active detection type protection method based on transformer excitation inductance parameter identification

Abstract

The invention provides an active detection type protection method based on transformer excitation inductance parameter identification, and relates to the technical field of power systems, and the method comprises the steps: firstly, collecting the circuit information of a transformer, and judging whether a protection element acts or not based on the circuit information; under the condition that the protection element acts, a detection signal is generated based on the converter; the method comprises the following steps: firstly, detecting a detection signal, injecting the detection signal into a transformer to excite the excitation inductance response of the transformer, and secondly, determining a target excitation inductance parameter model based on an excitation inductance parameter model calculation module of the transformer; then, determining an excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model; and finally, based on the excitation inductance characteristic value and a preset protection action criterion, whether a protection action is implemented is judged. According to the embodiment, the controllable detection signals are injected into the transformer, fault features are enhanced, and transformer fault early recognition and protection independent of power supply features can be achieved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power systems, and in particular to an active detection protection method based on transformer excitation inductance parameter identification. Background Art

[0002] Driven by the global "dual carbon" goal, building a new power system with new energy as the core has become a key path. With the substantial increase in the proportion of new energy power generation, the power system's transmission and distribution structure has undergone profound changes, and the trend of power electronics has become significant. This transformation has not only reshaped the operating characteristics and failure modes of the power system, but also posed a severe challenge to the traditional fault analysis and protection mechanism based on synchronous machines and linear superposition principles. The nonlinear controlled characteristics of new energy power sources and the complex response during faults put traditional protection principles such as fault component protection and distance protection at risk of performance degradation. At the same time, the particularity of the fault current of power electronic equipment has further exacerbated the problem of protection sensitivity and reliability.

[0003] Among the related technologies, the protection technology for new power systems is mainly developed from four aspects: recognition of fault characteristics, improvement of the adaptability of traditional protection, exploration of new protection principles, and coordination of control and protection. However, the existing technology has obvious shortcomings: on the one hand, the recognition of fault characteristics of new power systems is mostly limited to specific scenarios, lacking comprehensiveness and systematicity, and it is difficult to cover all typical working conditions; on the other hand, the adaptability of traditional protection in new power systems is insufficient, especially transformer protection, which lacks systematic evaluation and quantitative judgment under different scenarios and operating modes; furthermore, the research on new protection principles that do not rely on power supply characteristics is still in its infancy, and the innovation of protection principles for important components such as transformers is limited. Summary of the invention

[0004] The disclosed embodiments at least provide an active detection protection method based on transformer excitation inductance parameter identification, which can enhance fault characteristics by injecting a controllable detection signal into the transformer, thereby achieving early identification and protection of transformer faults that are independent of power supply characteristics.

[0005] The embodiment of the present disclosure provides an active detection protection method based on transformer excitation inductance parameter identification, including:

[0006] Collecting circuit information of the transformer, and judging whether the protection element is actuated based on the circuit information;

[0007] In the case where the protection element is actuated, a detection signal is generated based on the converter; and the detection signal is injected into the transformer to stimulate the excitation inductance response of the transformer, and a target excitation inductance parameter model is determined based on the excitation inductance parameter model calculation module of the transformer; the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the basis of the original excitation inductance parameter model;

[0008] Determining an excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model;

[0009] Based on the excitation inductance characteristic value and preset protection action criterion, it is determined whether to implement the protection action.

[0010] In some possible embodiments, the circuit information includes current information; and judging whether the protection element is actuated based on the circuit information includes:

[0011] Determining whether the current information meets a preset fault start criterion;

[0012] The preset fault start criterion includes:

[0013] |i d (i)-i d (iN)|>I dest

[0014] Among them, i d (i) represents the differential current at time i; N represents the number of sampling points in one cycle; I dest Indicates the differential current starting setting.

[0015] In some possible embodiments, after the detection signal is generated based on the current transformer, the method includes:

[0016] Determining a transfer function of a characteristic frequency control loop based on a proportional resonance control method, and adjusting a characteristic frequency current corresponding to the detection signal based on the transfer function of the characteristic frequency control loop;

[0017] The transfer function of the characteristic frequency control loop includes:

[0018]

[0019] Among them, u αβ represents the component of the modulation voltage in the αβ coordinate system; k p It is expressed as the first proportional resonance coefficient of the proportional resonance controller; k r It is represented as the second proportional resonance coefficient of the proportional resonance controller; i kαβ_ref Expressed as the reference value of the characteristic frequency current; i kαβIt is represented by the actual value of the characteristic frequency current; s represents the complex frequency; k represents the frequency multiple coefficient of the grid base frequency; w N Expressed as the grid fundamental voltage angular frequency.

[0020] In some possible embodiments, the transformer includes a single-phase double-winding transformer, and the circuit information also includes voltage information; before judging whether to implement the protection action based on the excitation inductance characteristic value and the preset protection action criterion, the method includes:

[0021] Constructing an excitation voltage equation of the single-phase double-winding transformer, and determining an excitation inductance parameter based on the excitation voltage equation of the single-phase double-winding transformer, the current information and the voltage information;

[0022] The excitation voltage equation includes:

[0023]

[0024] Among them, i 1 、i 2 They are respectively represented as primary current and secondary current; u 1 、u 1 Respectively represented as primary voltage and secondary voltage; R m Expressed as excitation resistance parameter; L m Expressed as the excitation inductance parameter.

[0025] In some possible embodiments, the preset protection action criterion includes:

[0026]

[0027] Among them, L av1 Expressed as the characteristic value of the excitation inductance; L mset Expressed as set value; L m (i) represents the excitation inductance parameter at time i; L m (i+T) represents the excitation inductance parameter at time i+T.

[0028] In some possible embodiments, judging whether to implement a protection action based on the excitation inductance characteristic value and a preset protection action criterion includes:

[0029] When the characteristic value of the excitation inductance meets the preset protection action criterion, it is determined to be an internal fault of the transformer and a protection action is implemented;

[0030] When the characteristic value of the excitation inductance does not satisfy the preset protection action criterion, no protection action is performed.

[0031] In some possible embodiments, after determining that there is an internal fault of the transformer and implementing a protection action, the steps include:

[0032] The transformer is continuously tested for fault clearance within a preset time after the protection action is implemented to determine whether the internal fault of the transformer is cleared.

[0033] The embodiment of the present disclosure provides an active detection protection device based on transformer excitation inductance parameter identification, including:

[0034] A component action judgment module, used to collect circuit information of the transformer and judge whether the protection component is actuated based on the circuit information;

[0035] A detection signal injection module is used to generate a detection signal based on the converter when the protection element is actuated; and inject the detection signal into the transformer to stimulate the excitation inductance response of the transformer, and determine the target excitation inductance parameter model based on the excitation inductance parameter model calculation module of the transformer; the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the basis of the original excitation inductance parameter model;

[0036] A feature set calculation module, used to determine the excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model;

[0037] The protection action judgment module is used to judge whether to implement the protection action based on the excitation inductance characteristic value and the preset protection action judgment criterion.

[0038] In some possible embodiments, the circuit information includes current information; and the component action judgment module is specifically used to:

[0039] Determining whether the current information meets a preset fault start criterion;

[0040] The preset fault start criterion includes:

[0041] |i d (i)-i d (iN)|>I dest

[0042] Among them, i d (i) represents the differential current at time i; N represents the number of sampling points in one cycle; I dest Indicates the differential current starting setting.

[0043] In some possible embodiments, the detection signal injection module is further used for:

[0044] Determining a transfer function of a characteristic frequency control loop based on a proportional resonance control method, and adjusting a characteristic frequency current corresponding to the detection signal based on the transfer function of the characteristic frequency control loop;

[0045] The transfer function of the characteristic frequency control loop includes:

[0046]

[0047] Among them, u αβ represents the component of the modulation voltage in the αβ coordinate system; k p It is expressed as the first proportional resonance coefficient of the proportional resonance controller; k r It is represented as the second proportional resonance coefficient of the proportional resonance controller; i kαβ_ref Expressed as the reference value of the characteristic frequency current; i kαβ It is represented by the actual value of the characteristic frequency current; s represents the complex frequency; k represents the frequency multiple coefficient of the grid base frequency; w N Expressed as the grid fundamental voltage angular frequency.

[0048] In some possible embodiments, the transformer includes a single-phase double-winding transformer, the circuit information also includes voltage information; and the protection action judgment module is further used to:

[0049] Constructing an excitation voltage equation of the single-phase double-winding transformer, and determining an excitation inductance parameter based on the excitation voltage equation of the single-phase double-winding transformer, the current information and the voltage information;

[0050] The excitation voltage equation includes:

[0051]

[0052] Among them, i 1 、i 2 They are respectively represented as primary current and secondary current; u 1 、u 1 Respectively represented as primary voltage and secondary voltage; R m Expressed as excitation resistance parameter; L m Expressed as the excitation inductance parameter.

[0053] In some possible embodiments, the preset protection action criterion includes:

[0054]

[0055] Among them, L av1 Expressed as the characteristic value of the excitation inductance; L mset Expressed as set value; L m (i) represents the excitation inductance parameter at time i; L m (i+T) represents the excitation inductance parameter at time i+T.

[0056] In some possible embodiments, the protection action determination module is specifically used to:

[0057] When the characteristic value of the excitation inductance meets the preset protection action criterion, it is determined to be an internal fault of the transformer and a protection action is implemented;

[0058] When the characteristic value of the excitation inductance does not satisfy the preset protection action criterion, no protection action is performed.

[0059] In some possible embodiments, the protection action determination module is further used to:

[0060] The transformer is continuously tested for fault clearance within a preset time after the protection action is implemented to determine whether the internal fault of the transformer is cleared.

[0061] An embodiment of the present disclosure provides a computer device, including: a processor, a memory and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the computer device is running, the processor and the memory communicate via the bus, and when the machine-readable instructions are executed by the processor, an active detection protection method based on transformer excitation inductance parameter identification as described in any possible implementation manner described above is performed.

[0062] An embodiment of the present disclosure provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the active detection protection method based on transformer excitation inductance parameter identification as described in any possible implementation manner described above is implemented.

[0063] The active detection protection method based on transformer excitation inductance parameter identification provided in the embodiments of the present disclosure is that the detection signal generated by the detection protection is actively generated, and its waveform is stable and controllable, so that the waveform received by the transformer can be expected. In this way, by injecting a controllable detection signal into the transformer and enhancing the fault characteristics, early identification and protection of transformer faults that do not rely on power supply characteristics can be achieved.

[0064] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required to be cited in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used together with the specification to illustrate the technical solutions of the present disclosure. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 A flow chart of an active detection protection method based on transformer excitation inductance parameter identification provided by an embodiment of the present disclosure is shown;

[0067] Figure 2 A schematic diagram of an active detection protection method based on transformer excitation inductance parameter identification provided by an embodiment of the present disclosure is shown;

[0068] Figure 3 A structural schematic diagram of an active detection protection device based on transformer excitation inductance parameter identification provided by an embodiment of the present disclosure is shown;

[0069] Figure 4 A schematic diagram of the structure of a computer device provided by an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical scheme and advantages of the embodiments of the present disclosure clearer, the technical scheme in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments. The components of the embodiments of the present disclosure generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the present disclosure for protection, but merely represents the selected embodiments of the present disclosure. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present disclosure.

[0071] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0072] The term "and / or" herein only describes an association relationship, indicating that three relationships may exist. For example, A and / or B may represent the following three situations: A exists alone, A and B exist at the same time, and B exists alone. In addition, the term "at least one" herein represents any combination of at least two of any one or more of a plurality of. For example, including at least one of A, B, and C may represent including any one or more elements selected from the set consisting of A, B, and C.

[0073] Driven by the global "dual carbon" goals, building a new power system with new energy as the main body has become a key strategic path. The high proportion of access to new energy such as wind power and photovoltaics has greatly changed the structure of the power system, making the characteristics of power electronics increasingly prominent. This transformation has not only improved the green level of the power system, but also brought unprecedented technical challenges. In particular, the nonlinear characteristics of new energy power electronic equipment and the complex response during faults have severely impacted the traditional fault analysis method and relay protection mechanism based on the linear superposition principle, resulting in a decline in protection performance, such as failure of fault component protection and reduced sensitivity of differential protection, which may directly threaten the safety and stability of the power system.

[0074] The study found that although the research on new power system protection technology has made some progress, there are still many shortcomings. On the one hand, the research on the fault characteristics and laws of new power systems is mostly limited to specific scenarios, lacking comprehensiveness and systematicness, and it is difficult to cover all possible operating conditions and fault modes. On the other hand, the adaptability of traditional protection technology in new power systems is insufficient, especially in the face of complex control strategies of power electronic equipment, the boundary conditions and performance evaluation of protection principles lack clear standards, resulting in the accuracy and timeliness of protection actions cannot be fully guaranteed. In addition, the research on new relay protection principles that do not rely on power supply characteristics is still in its infancy, and the coordinated control technology of power electronic equipment and protection systems is also mainly focused on DC systems, and the research on active signal injection protection in AC systems is relatively scarce. These problems jointly restrict the development of new power system protection technology, making it difficult to meet its high reliability and high sensitivity protection needs.

[0075] Based on the above research, an active detection protection method based on transformer excitation inductance parameter identification is provided in an embodiment of the present disclosure. First, the circuit information of the transformer is collected, and whether the protection element is actuated is determined based on the circuit information; when the protection element is actuated, a detection signal is generated based on the converter; and the detection signal is injected into the transformer to stimulate the excitation inductance response of the transformer. Secondly, a target excitation inductance parameter model is determined based on the excitation inductance parameter model calculation module of the transformer, wherein the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the basis of the original excitation inductance parameter model; then, the excitation inductance characteristic value is determined based on the original excitation inductance parameter model and the target excitation inductance parameter model; finally, based on the excitation inductance characteristic value and the preset protection action criterion, it is determined whether to implement the protection action.

[0076] In the disclosed embodiment, since the detection signal generated by the detection protection is actively generated, its waveform is stable and controllable, so that the waveform received by the transformer can be expected. In this way, by injecting a controllable detection signal into the transformer and enhancing the fault characteristics, early identification and protection of transformer faults that do not rely on power supply characteristics can be achieved.

[0077] To facilitate understanding of this embodiment, the execution subject of the active detection protection method based on transformer excitation inductance parameter identification provided by the embodiment of the present disclosure is first introduced in detail. The execution subject of the active detection protection method based on transformer excitation inductance parameter identification provided by the embodiment of the present disclosure is a computer device. The computer device can be a server. Among them, the server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud storage, big data and artificial intelligence platforms.

[0078] The active detection protection method based on transformer excitation inductance parameter identification provided by the embodiment of the present application is described in detail below in conjunction with the accompanying drawings. Figure 1 As shown, it is a flow chart of an active detection protection method based on transformer excitation inductance parameter identification provided by an embodiment of the present disclosure, and the method includes the following S101-S104:

[0079] S101, collecting circuit information of the transformer, and judging whether the protection element is actuated based on the circuit information.

[0080] It is understandable that in the power system, the transformer is a key power conversion device, and its operating status is directly related to the safety and stability of the power grid. Therefore, it is particularly important to carry out real-time monitoring and fault diagnosis of the transformer. Here, the circuit information of the transformer mainly includes current information and voltage information. Specifically, in order to accurately identify transformer faults and take corresponding protection measures, fault start criteria are usually set according to the design parameters, operating experience and power grid safety requirements of the transformer. Therefore, after collecting the circuit information of the transformer, it can be judged according to the preset fault start criteria whether the current information of the transformer meets the preset fault start criteria to determine whether the protection element is activated.

[0081] Here, the preset fault start criterion can be expressed as:

[0082] |i d (i)-i d (iN)|>I dest ;

[0083] Among them, i d (i) represents the differential current at time i; N represents the number of sampling points in one cycle; I dest Expressed as differential current starting setting. Here, differential current refers to the difference between the currents flowing through two or more paths. In power systems, differential current is usually determined by the difference between the currents measured by a current transformer or a current transformer group. For example, in the transformer protection process, each phase has a corresponding current transformer to measure the output current signal, and the differential current is obtained by calculating the difference between the currents of each phase.

[0084] In the disclosed embodiment, the criterion for determining whether the protection element is activated is set based on the differential current fault component, and has a high sensitivity, which can ensure that in an abnormal operating state (i.e., the system has not completely failed, but has deviated from the normal operating parameters), the use of this criterion can also ensure that the protection element can be reliably activated, thereby responding in time and protecting the stable operation of the entire power system.

[0085] S102, when the protection element is actuated, generating a detection signal based on the converter; injecting the detection signal into the transformer to stimulate the excitation inductance response of the transformer, and determining a target excitation inductance parameter model based on the excitation inductance parameter model calculation module of the transformer.

[0086] Here, in the relevant protection technology, the parameter identification algorithm faces a problem, that is, the transient quantity or high-order harmonic quantity in the transformer fault contains a large amount of fault information. At this time, equations can be written for parameter calculation, but most of the transient quantities only exist for a short period of time at the beginning of the fault, and then quickly decay to zero. This will cause the equation about the transient quantity to become an ill-conditioned equation, so that the error of the identified parameters is large or even wrong. Therefore, in the present disclosure, a method of actively generating a detection signal and injecting it into the transformer is proposed to ensure the stability and controllability of its waveform, thereby avoiding the occurrence of the above-mentioned problems.

[0087] Specifically, when the protection element is activated, a detection signal is generated by the converter, and the generated detection information is injected into the transformer to stimulate the excitation inductance response of the transformer, which is then used for fault diagnosis or status monitoring. Among them, the converter is a power electronic device that can realize the transformation and control of the input power signal by adjusting parameters such as voltage, current and frequency. In the present disclosure, the converter is used to generate a specific detection signal, and 8 times the grid base frequency current (ie 400Hz) can be selected as the detection signal to optimize the current protection performance. Among them, the amplitude of the detection signal needs to comprehensively consider the detection difficulty of the protection and the requirements of the power quality of the grid: if the amplitude of the injected characteristic signal is too small, it will increase the difficulty of identification and detection at the protection; if the amplitude is too large, it will cause the disturbance in the grid to exceed the standard, which will have a negative impact on the power quality. Taking into account the influence of both, the present disclosure sets the maximum amplitude of the detection signal to 10% of the maximum current amplitude output by the converter.

[0088] In some other embodiments, the specific value of the detection signal may also be 6 times the base frequency current of the power grid (ie, 300 Hz) or other values, which are not specifically limited here.

[0089] For example, in order to more accurately control and monitor the state of the transformer equipment, especially when it is necessary to generate and inject a detection signal of a specific frequency to stimulate a specific response of the transformer, it is particularly important to flexibly control the parameters of the detection signal (i.e., the characteristic frequency current). In order to achieve this purpose, the present disclosure proposes a design that combines proportional resonant control (PRC) with a characteristic frequency control loop to achieve precise adjustment of the characteristic frequency current of the detection signal. Specifically, the proportional resonant control method can ensure that the system responds quickly and accurately to a specific frequency (i.e., the characteristic frequency of the detection signal) because of its extremely high gain and zero static error characteristics at a specific frequency, thereby achieving rapid tracking of instructions. During the detection signal injection process, by adjusting the transfer function parameters of the characteristic frequency control loop based on the proportional resonant control design, the characteristic frequency current corresponding to the detection signal can be flexibly controlled so that it can accurately match the predetermined frequency and amplitude requirements. In addition, in order to further optimize the performance of the system, especially to reduce the impact of the characteristic frequency negative sequence current on the system, the present disclosure also feeds forward the characteristic frequency negative sequence voltage component to the modulation wave, specifically utilizing the direct relationship between the negative sequence voltage component and the negative sequence current, and effectively suppresses the generation of the characteristic frequency negative sequence current through feedforward compensation. In this way, not only can the stability and reliability of the system be improved, but also the accuracy and flexibility of the detection signal control can be further improved.

[0090] Specifically, the transfer function of the characteristic frequency control loop obtained by combining the proportional resonance control method and the feedforward compensation method is as follows:

[0091]

[0092] Among them, u αβ represents the component of the modulation voltage in the αβ coordinate system; k p It is expressed as the first proportional resonance coefficient of the proportional resonance controller; k r It is represented as the second proportional resonance coefficient of the proportional resonance controller; i kαβ_ref Expressed as the reference value of the characteristic frequency current; i kαβ It is represented by the actual value of the characteristic frequency current; s represents the complex frequency; k represents the frequency multiple coefficient of the grid base frequency; w N Expressed as the grid fundamental voltage angular frequency.

[0093] It is understandable that when the detection signal is generated based on the converter and injected into the transformer, the excitation inductance of the transformer will be stimulated to produce a specific response. In order to capture and quantify the response changes generated by this transformer, the excitation inductance parameter model calculation module of the transformer can be used. First, based on the original design parameters of the transformer or the data obtained by previous measurements, an original excitation inductance parameter model is established, which describes the excitation inductance characteristics of the transformer under ideal or standard conditions. Then, since the transformer will be affected by various factors (such as temperature changes, load fluctuations, aging, etc.) in actual operation, its excitation inductance characteristics will deviate from the ideal state. Therefore, after the protection element is activated and the detection signal is injected into the transformer, the change information of the actual excitation inductance characteristics can be obtained by monitoring the response of the transformer to the detection signal. Then, the excitation inductance parameter model calculation module of the transformer will receive these real-time data, including the detection signal and the response signal excited by it, and then use mathematical algorithms and model updating technology to adjust the original excitation inductance parameter model, aiming to superimpose the detected excitation inductance response on the original model, so as to obtain a new target excitation inductance parameter model that is closer to the current actual state.

[0094] Among them, the excitation inductance parameter model calculation module can use parameter estimation, system identification or machine learning methods to model and analyze the relationship between the detection signal and the response signal, and then derive the specific parameter values ​​of the target excitation inductance parameter model.

[0095] S103: Determine an excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model.

[0096] Exemplarily, after obtaining the original excitation inductance parameter model and the target excitation inductance parameter model, the two models can be compared and analyzed. Specifically, the difference in the excitation inductance values ​​of the two models at key frequency points or working conditions is focused on, and these differences will reflect the changes in the excitation inductance characteristics of the transformer due to various factors (such as load changes, temperature fluctuations, etc.). And through mathematical calculations or data processing techniques, the excitation inductance characteristic value that can characterize the current excitation inductance state of the transformer is extracted from the difference.

[0097] Here, taking a single-phase two-winding transformer as an example, first construct the excitation voltage equation of the single-phase two-winding transformer, and calculate the excitation inductance parameters based on the excitation voltage equation of the single-phase two-winding transformer and the current information and voltage information corresponding to the single-phase two-winding transformer; and calculate the excitation inductance characteristic value based on the excitation inductance parameters. Among them, the excitation voltage equation includes:

[0098]

[0099] Among them, i 1 、i2 They are respectively represented as primary current and secondary current; u 1 、u 1 Respectively represented as primary voltage and secondary voltage; R m Expressed as excitation resistance parameter; L m It is expressed as the excitation inductance parameter. Here, the primary current refers to the current flowing through the primary side of the transformer. In the power system, the primary side is usually connected to the power supply and is the side where the power is input. Similarly, the primary voltage refers to the voltage on the primary side of the transformer. The secondary current is the current flowing out of the low-voltage side (also called the secondary side) of the transformer, which is used to supply the load; similarly, the complex voltage refers to the voltage on the low-voltage side (also called the secondary side) of the transformer.

[0100] In some other embodiments, the transformer type may also be a three-winding transformer, a multi-winding transformer, etc., which is not specifically limited here.

[0101] S104: Determine whether to implement a protection action based on the characteristic value of the excitation inductance and a preset protection action criterion.

[0102] Here, the preset protection action criteria are as follows:

[0103]

[0104] Among them, L av1 Expressed as the characteristic value of the excitation inductance; L mset Expressed as set value; L m (i) represents the excitation inductance parameter at time i; L m (i+T) represents the excitation inductance parameter at time i+T.

[0105] Exemplarily, it is proposed in the present disclosure that, in the case of no-load closing, the time for the transformer core to operate in the saturation zone will not exceed half of the power frequency cycle (i.e., 10ms). Considering a certain margin, T can be taken as every sampling moment within 8 to 12ms. If Δt represents the sampling interval of the protection device, k1 represents the sampling point number (k1=0, 1, 2, 3…N1, N1 is the number of sampling points within 8 to 12ms), then T can be expressed as T=(8+k1Δt)ms, and T≤12ms. In some other embodiments, the value of T can be set according to actual requirements, and is not specifically limited here.

[0106] It is understandable that when the characteristic value of the excitation inductance meets the preset protection action criteria, it will be determined that a fault may occur inside the transformer, such as a winding short circuit, insulation damage, or core saturation. These fault conditions may cause the transformer to overheat, abnormally increase the current, or fluctuate the voltage, thereby posing a threat to the stable operation of the power system. Therefore, after detecting such an abnormal situation, the protection system will respond quickly and implement corresponding protection actions, such as cutting off the connection between the faulty transformer and the power grid to prevent the fault from expanding and protecting other equipment from damage. On the contrary, if the characteristic value of the excitation inductance does not meet the preset protection action criteria, that is, it is within the normal range, it means that the excitation inductance is volatile, and it should be judged as an excitation inrush current state at this time, and no protection action is required. In this case, the transformer can continue to play its due role in the power system and provide a stable and reliable power supply to the load.

[0107] Specifically, the transformer is continuously tested for fault removal within a preset time after the protection action is implemented to determine whether the internal fault of the transformer has been removed. Here, the fault removal detection method may include re-collecting the circuit information of the transformer, analyzing whether the voltage, current and other parameters have returned to normal levels, and checking whether the state of the protection element has been restored from the action state. If within the preset time, the system detects that the various parameters of the transformer have returned to normal and there are no abnormal phenomena inside, it can be considered that the fault has been removed, and the system will automatically restore power supply to the transformer. On the contrary, if it is detected that the fault has not been removed or there is a new abnormal situation, the system will continue to execute the protection state and may trigger further fault handling processes, such as issuing emergency alarms, notifying maintenance personnel to conduct on-site maintenance, etc., to ensure the safe and stable operation of the power system.

[0108] The active detection protection method based on transformer excitation inductance parameter identification provided in the embodiments of the present disclosure is that the detection signal generated by the detection protection is actively generated, and its waveform is stable and controllable, so that the waveform received by the transformer can be expected. In this way, by injecting a controllable detection signal into the transformer and enhancing the fault characteristics, early identification and protection of transformer faults that do not rely on power supply characteristics can be achieved.

[0109] Combine the following Figure 2, the active detection protection method based on transformer excitation inductance parameter identification proposed in the present disclosure is generally described. First, the circuit information (current information and voltage information) of the transformer is collected to provide basic data for subsequent protection judgment; then, it is judged whether the current information meets the preset fault start criterion to determine whether the protection element is in action. Subsequently, when the protection element is in action, a detection signal is generated based on the converter and injected into the transformer to stimulate the excitation inductance response of the transformer. In this process, the target excitation inductance parameter model formed by superimposing the excitation inductance response on the basis of the original excitation inductance parameter model will be calculated according to the excitation inductance parameter model calculation module model of the transformer for comparison and analysis. Then, by comparing and analyzing the original model and the target model, it is possible to evaluate whether the excitation inductance parameter of the transformer has changed. If a parameter change is detected, the characteristic value of the excitation inductance is further extracted, and these characteristic values ​​will be used for subsequent protection action judgment. Finally, the extracted excitation inductance characteristic value is compared with the preset protection action criterion. If the criterion condition is met, the protection action is immediately implemented to ensure the safe operation of the transformer and the stability of the power system.

[0110] Those skilled in the art will appreciate that, in the above method of specific implementation, the order in which the steps are written does not imply a strict execution order and does not constitute any limitation on the implementation process. The specific execution order of the steps should be determined by their functions and possible internal logic.

[0111] Based on the same inventive concept, the embodiment of the present disclosure also provides an active detection protection device based on transformer excitation inductance parameter identification corresponding to the active detection protection method based on transformer excitation inductance parameter identification. Since the principle of solving the problem by the device in the embodiment of the present disclosure is similar to the above-mentioned active detection protection method based on transformer excitation inductance parameter identification in the embodiment of the present disclosure, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0112] Reference Figure 3 FIG. 1 is a schematic diagram of an active detection protection device 300 based on transformer excitation inductance parameter identification provided by an embodiment of the present disclosure, wherein the device comprises:

[0113] The component action judgment module 301 is used to collect the circuit information of the transformer and judge whether the protection component is in action based on the circuit information;

[0114] A detection signal injection module 302 is used to generate a detection signal based on the converter when the protection element is actuated; and inject the detection signal into the transformer to stimulate the excitation inductance response of the transformer, and determine a target excitation inductance parameter model based on the excitation inductance parameter model calculation module of the transformer; the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the basis of the original excitation inductance parameter model;

[0115] A feature set calculation module 303, configured to determine a characteristic value of the excitation inductance based on the original excitation inductance parameter model and the target excitation inductance parameter model;

[0116] The protection action judgment module 304 is used to judge whether to implement a protection action based on the excitation inductance characteristic value and a preset protection action judgment criterion.

[0117] In some possible embodiments, the circuit information includes current information; the component action determination module 301 is specifically used for:

[0118] Determining whether the current information meets a preset fault start criterion;

[0119] The preset fault start criterion includes:

[0120] |i d (i)-i d (iN)|>I dest

[0121] Among them, i d (i) represents the differential current at time i; N represents the number of sampling points in one cycle; I dest Indicates the differential current starting setting.

[0122] In some possible embodiments, the detection signal injection module 302 is further used for:

[0123] Determining a transfer function of a characteristic frequency control loop based on a proportional resonance control method, and adjusting a characteristic frequency current corresponding to the detection signal based on the transfer function of the characteristic frequency control loop;

[0124] The transfer function of the characteristic frequency control loop includes:

[0125]

[0126] Among them, u αβ represents the component of the modulation voltage in the αβ coordinate system; k p It is expressed as the first proportional resonance coefficient of the proportional resonance controller; k r It is represented as the second proportional resonance coefficient of the proportional resonance controller; i kαβ_refExpressed as the reference value of the characteristic frequency current; i kαβ It is represented by the actual value of the characteristic frequency current; s represents the complex frequency; k represents the frequency multiple coefficient of the grid base frequency; w N Expressed as the grid fundamental voltage angular frequency.

[0127] In some possible embodiments, the transformer includes a single-phase double-winding transformer, and the circuit information also includes voltage information; the protection action determination module 304 is further used to:

[0128] Constructing an excitation voltage equation of the single-phase double-winding transformer, and determining an excitation inductance parameter based on the excitation voltage equation of the single-phase double-winding transformer, the current information and the voltage information;

[0129] The excitation voltage equation includes:

[0130]

[0131] Among them, i 1 、i 2 They are respectively represented as primary current and secondary current; u 1 、u 1 Respectively represented as primary voltage and secondary voltage; R m Expressed as excitation resistance parameter; L m Expressed as the excitation inductance parameter.

[0132] In some possible embodiments, the preset protection action criterion includes:

[0133]

[0134] Among them, L av1 Expressed as the characteristic value of the excitation inductance; L mset Expressed as set value; L m (i) represents the excitation inductance parameter at time i; L m (i+T) represents the excitation inductance parameter at time i+T.

[0135] In some possible embodiments, the protection action determination module 304 is specifically used to:

[0136] When the characteristic value of the excitation inductance meets the preset protection action criterion, it is determined to be an internal fault of the transformer and a protection action is implemented;

[0137] When the characteristic value of the excitation inductance does not satisfy the preset protection action criterion, no protection action is performed.

[0138] In some possible embodiments, the protection action determination module 304 is further configured to:

[0139] The transformer is continuously tested for fault clearance within a preset time after the protection action is implemented to determine whether the internal fault of the transformer is cleared.

[0140] Based on the same technical concept, the embodiment of the present disclosure also provides a computer device. Figure 4 4 is a schematic diagram of the structure of a computer device 400 provided in an embodiment of the present disclosure, including a processor 401, a memory 402, and a bus 403. The memory 402 is used to store execution instructions, including a memory 4021 and an external memory 4022; the memory 4021 is also called an internal memory, which is used to temporarily store the operation data in the processor 401 and the data exchanged with the external memory 4022 such as a hard disk. The processor 401 exchanges data with the external memory 4022 through the memory 4021.

[0141] In the embodiment of the present application, the memory 402 is specifically used to store the application code for executing the solution of the present application, and the execution is controlled by the processor 401. That is, when the computer device 400 is running, the processor 401 communicates with the memory 402 through the bus 403, so that the processor 401 executes the application code stored in the memory 402, and then executes the method described in any of the above embodiments.

[0142] Among them, the memory 402 can be, but is not limited to, random access memory (Random Access Memory, RAM), read only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-Only Memory, PROM), erasable programmable read-only memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable read-only memory (Electric Erasable Programmable Read-Only Memory, EEPROM), etc.

[0143] Processor 401 may be an integrated circuit chip with signal processing capabilities. The above-mentioned processor may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The disclosed methods, steps and logic block diagrams in the embodiments of the present invention may be implemented or executed. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0144] It is to be understood that the structure illustrated in the embodiment of the present application does not constitute a specific limitation on the computer device 400. In other embodiments of the present application, the computer device 400 may include more or fewer components than shown in the figure, or combine some components, or split some components, or arrange the components differently. The components shown in the figure may be implemented in hardware, software, or a combination of software and hardware.

[0145] The embodiment of the present disclosure also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the active detection protection method based on transformer excitation inductance parameter identification described in the above method embodiment are executed. The storage medium can be a volatile or non-volatile computer-readable storage medium.

[0146] The embodiments of the present disclosure also provide a computer program product, which carries a program code. The instructions included in the program code can be used to execute the steps of the active detection protection method based on transformer excitation inductance parameter identification described in the above method embodiment. For details, please refer to the above method embodiment, which will not be repeated here.

[0147] The computer program product may be implemented in hardware, software or a combination thereof. In one optional embodiment, the computer program product is implemented as a computer storage medium. In another optional embodiment, the computer program product is implemented as a software product, such as a software development kit (SDK).

[0148] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present disclosure, it should be understood that the disclosed system and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0149] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0150] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0151] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present disclosure, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present disclosure. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0152] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present disclosure, which are used to illustrate the technical solutions of the present disclosure, rather than to limit them. The protection scope of the present disclosure is not limited thereto. Although the present disclosure is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present disclosure, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure, and should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. An active detection protection method based on transformer excitation inductance parameter identification, characterized in that: include: Collecting circuit information of the transformer, and judging whether the protection element is actuated based on the circuit information; When the protection element is actuated, generating a detection signal based on the current transformer; The detection signal is injected into a transformer to stimulate the excitation inductance response of the transformer, and a target excitation inductance parameter model is determined based on the excitation inductance parameter model calculation module of the transformer; the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the original excitation inductance parameter model; Determining an excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model; Based on the excitation inductance characteristic value and preset protection action criterion, it is determined whether to implement the protection action.

2. The method according to claim 1, characterized in that The circuit information includes current information; The determining whether the protection element is actuated based on the circuit information includes: Determining whether the current information meets a preset fault start criterion; The preset fault start criteria include: |i d (i)-i d (i-N)|>I dest Among them, i d (i) represents the differential current at time i; N represents the number of sampling points in one cycle; I dest Indicates the differential current starting setting.

3. The method according to claim 1, characterized in that After the detection signal is generated based on the current transformer, the method includes: Determining a transfer function of a characteristic frequency control loop based on a proportional resonance control method, and adjusting a characteristic frequency current corresponding to the detection signal based on the transfer function of the characteristic frequency control loop; The transfer function of the characteristic frequency control loop includes: Among them, u αβ represents the component of the modulation voltage in the αβ coordinate system; k p It is expressed as the first proportional resonance coefficient of the proportional resonance controller; k r It is represented as the second proportional resonance coefficient of the proportional resonance controller; i kαβ_ref Expressed as the reference value of the characteristic frequency current; i kαβ It is represented by the actual value of the characteristic frequency current; s represents the complex frequency; k represents the frequency multiple coefficient of the grid base frequency; w N Expressed as the grid fundamental voltage angular frequency.

4. The method according to claim 2, characterized in that: The transformer includes a single-phase double-winding transformer, and the circuit information also includes voltage information; before judging whether to implement the protection action based on the excitation inductance characteristic value and the preset protection action criterion, the method includes: Constructing an excitation voltage equation of the single-phase double-winding transformer, and determining an excitation inductance parameter based on the excitation voltage equation of the single-phase double-winding transformer, the current information and the voltage information; The excitation voltage equation includes: Among them, i1 and i2 represent the primary current and secondary current respectively; u1 and u1 represent the primary voltage and secondary voltage respectively; R m Expressed as excitation resistance parameter; L m Expressed as the excitation inductance parameter.

5. The method according to claim 4, characterized in that The preset protection action criteria include: Among them, L av1 Expressed as the characteristic value of the excitation inductance; L mset Expressed as set value; L m (i) represents the excitation inductance parameter at time i; L m (i+T) represents the excitation inductance parameter at time i+T.

6. The method according to claim 5, characterized in that The determining whether to implement a protection action based on the excitation inductance characteristic value and a preset protection action criterion includes: When the characteristic value of the excitation inductance meets the preset protection action criterion, it is determined to be an internal fault of the transformer and a protection action is implemented; When the characteristic value of the excitation inductance does not satisfy the preset protection action criterion, no protection action is performed.

7. The method according to claim 6, characterized in that After determining that the transformer has an internal fault and implementing a protection action, the method includes: The transformer is continuously tested for fault clearance within a preset time after the protection action is implemented to determine whether the internal fault of the transformer is cleared.

8. An active detection protection device based on transformer excitation inductance parameter identification, characterized in that: include: A component action judgment module, used to collect circuit information of the transformer and judge whether the protection component is actuated based on the circuit information; A detection signal injection module, used for generating a detection signal based on the converter when the protection element is actuated; The detection signal is injected into a transformer to stimulate the excitation inductance response of the transformer, and a target excitation inductance parameter model is determined based on the excitation inductance parameter model calculation module of the transformer; the target excitation inductance parameter model is obtained by superimposing the excitation inductance response on the original excitation inductance parameter model; A feature set calculation module, used to determine the excitation inductance characteristic value based on the original excitation inductance parameter model and the target excitation inductance parameter model; The protection action judgment module is used to judge whether to implement the protection action based on the excitation inductance characteristic value and the preset protection action judgment criterion.

9. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

10. A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 7 is implemented.

Images