Grounding protection method and device for high voltage fully enclosed vacuum environmentally friendly GIS equipment

Abstract

The present invention relates to a grounding protection method and device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment. The method: decouple and analyze the zero-sequence component and negative-sequence component of the metal shell current and the internal conductor current of the GIS equipment to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model; perform SF6 gas pressure compensation and vacuum degree compensation operations based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value; calculate the amplitude ratio and phase angle difference between the metal shell current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value to obtain a fault judgment threshold, and establish a three-level protection configuration system; input the three-level protection configuration system into a digital signal processor to perform real-time monitoring, and obtain the action instructions and fault information of the hierarchical protection. The present invention effectively overcomes the limitations of grounding fault detection in a fully enclosed environment and improves the accuracy of fault identification.

Description

Technical Field

[0001] The present invention relates to the technical field of GIS equipment, and in particular to a grounding protection method and device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment. Background Art

[0002] With the continuous development of power systems, high-voltage fully enclosed vacuum environmentally friendly GIS equipment has been widely used due to its compact structure and good environmental performance. However, due to its fully enclosed characteristics, its ground fault detection faces unique challenges. The traditional ground fault detection technology using current transformer measurement has limitations in SF6 gas insulation environments. When a ground fault occurs in the metal casing or internal conductor of the GIS equipment, the fault current returns through the grounding protection device and the metal casing grounding grid, and the detection current generated is small, which is difficult to accurately judge.

[0003] In addition, the SF6 gas pressure fluctuation and vacuum change under the fully enclosed structure will cause a slight displacement of the metal shielding layer, generating current characteristics similar to ground faults, which increases the difficulty of fault identification. Especially in the ultra-high voltage operating environment, the insulation performance of the equipment will deteriorate over time, and this change will affect the reliability of the grounding protection system. Summary of the invention

[0004] The main purpose of the present invention is to provide a grounding protection method and device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment. The present invention effectively overcomes the limitations of grounding fault detection in a fully enclosed environment and improves the accuracy of fault identification.

[0005] To achieve the above object, the present invention provides a grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, comprising the following steps:

[0006] The zero-sequence component and negative-sequence component decoupling analysis of the metal shell current and internal conductor current of the GIS equipment are carried out to obtain the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model;

[0007] Based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model, SF6 gas pressure compensation and vacuum degree compensation operations are performed to obtain a compensated zero-sequence current value and a compensated negative-sequence current value;

[0008] Calculate the amplitude ratio and phase angle difference between the metal casing current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain the fault criterion threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection;

[0009] The three-level protection configuration system is input into a digital signal processor to perform real-time monitoring to obtain action instructions and fault information of the hierarchical protection.

[0010] The present invention also provides a grounding protection device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, comprising:

[0011] A decoupling analysis unit is used to perform zero-sequence component and negative-sequence component decoupling analysis on the metal shell current and internal conductor current of the GIS equipment to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model;

[0012] A compensation operation unit, used for performing SF6 gas pressure compensation and vacuum degree compensation operations based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value;

[0013] A calculation unit, used to calculate the amplitude ratio and phase angle difference between the metal shell current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain a fault criterion threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection;

[0014] The real-time monitoring unit is used to input the three-level protection configuration system into a digital signal processor to perform real-time monitoring and obtain action instructions and fault information of the hierarchical protection.

[0015] In summary, the technical solution provided by the present invention effectively overcomes the limitations of ground fault detection in a fully enclosed environment and improves the accuracy of fault identification by decoupling analysis of zero-sequence components and negative-sequence components, combined with SF6 gas pressure and vacuum compensation. A multiple protection configuration system is adopted to achieve coordinated cooperation of differential protection, impedance protection and overcurrent protection, so that the protection system has higher reliability and selectivity. The introduction of fuzzy control algorithm to adaptively optimize the protection parameters enables the system to automatically adjust the protection parameters according to the operating status of the equipment, thereby enhancing the adaptability of the system. By establishing a complete fault information collection and processing mechanism, real-time monitoring and evaluation of the operating status of GIS equipment is achieved, providing reliable data support for equipment maintenance. The present invention fully considers the influence of environmental factors such as SF6 gas pressure fluctuations and vacuum changes, and improves the operating stability of the system in complex environments through a comprehensive compensation mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the steps of a grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment in one embodiment of the present invention;

[0017] Figure 2 It is a structural block diagram of a grounding protection device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment in one embodiment of the present invention.

[0018] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0020] Reference Figure 1 This embodiment provides a grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, including the following steps:

[0021] S1, perform zero-sequence component and negative-sequence component decoupling analysis on the metal shell current and internal conductor current of the GIS equipment to obtain the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model;

[0022] Among them, the current signal of the GIS equipment is sampled, and the spectrum of the metal shell current and the spectrum of the internal conductor current are calculated using the fast Fourier transform algorithm to obtain the metal shell current spectrum and the internal conductor current spectrum. The symmetrical component transformation matrix operation is performed on the metal shell current spectrum and the internal conductor current spectrum to extract the zero-sequence current component and the negative-sequence current component. Symmetrical component transformation is a method of decomposing the three-phase unbalanced current into symmetrical components, in which the zero-sequence component is used to reflect the characteristics of the symmetrical grounding fault, and the negative-sequence component is used to identify the unbalanced state of the system. By applying Clarke transformation or Park transformation, the three-phase current is converted to the α-β-0 coordinate system, and then after mathematical operations, the zero-sequence current component and the negative-sequence current component are obtained. Based on the zero-sequence current component, a zero-sequence impedance equation is constructed, and the metal shell grounding impedance and the internal conductor grounding impedance are introduced into the equation to more accurately describe the zero-sequence characteristics of the GIS equipment. In the zero-sequence current path, there are grounding impedances in both the metal shell and the internal conductor. These impedances affect the flow characteristics of the zero-sequence current. When constructing the zero-sequence equivalent circuit, the influence of these grounding impedances is accurately modeled. In mathematical expression, the zero-sequence impedance equation is expressed in matrix form, which includes the distribution relationship of the metal shell grounding impedance, the GIS internal conductor grounding impedance and the zero-sequence current, forming the node admittance matrix of the zero-sequence network. At the same time, in order to describe the characteristics of GIS equipment under the negative-sequence current component, the negative-sequence impedance equation is constructed, and the mutual inductance impedance between the metal shell and the internal conductor is introduced into the equation. Since the negative-sequence component is mainly used to describe the unbalanced state in the system, its distribution law is different from that of the zero-sequence component. The coupling between the metal shell and the internal conductor needs to be considered when modeling. The existence of mutual inductance impedance will affect the flow of negative-sequence current in the system, thereby affecting the overall characteristics of the negative-sequence network. When establishing the negative-sequence impedance equation, it is included in the calculation, and the node admittance matrix of the negative-sequence network is constructed based on this. According to the node admittance matrix of the zero-sequence network, the network equation of the zero-sequence equivalent circuit is solved by the node voltage method to obtain the zero-sequence equivalent circuit model. The node voltage method is a circuit analysis method that calculates the distribution of current and voltage by solving the node voltage equation. In the zero-sequence equivalent circuit, all zero-sequence current paths are described as a mathematical model, and the distribution of zero-sequence current and the fault point in the GIS system are determined based on the calculation results of the node voltage method. Similarly, the network equation of the negative-sequence equivalent circuit is solved by the node voltage method according to the node admittance matrix of the negative-sequence network to obtain the negative-sequence equivalent circuit model. Due to the different flow modes of negative-sequence current and zero-sequence current, their corresponding equivalent circuit models are also different, but the solution process is similar, both relying on the node voltage method to calculate the voltage distribution of each node, and thus deriving the equivalent circuit structure of the entire network. By establishing the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model, the electrical characteristics of GIS equipment under ground fault and unbalanced conditions are described.

[0023] S2, performing SF6 gas pressure compensation and vacuum degree compensation calculations based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value;

[0024] Specifically, real-time data of SF6 gas pressure is obtained. The real-time pressure value inside the GIS equipment is obtained by measuring the SF6 gas pressure sensor. The collected data is smoothed by a sliding window filtering method to eliminate instantaneous interference and improve measurement accuracy, and the filtered SF6 gas pressure value is obtained. The filtered pressure value is calculated by ratio with the standard atmospheric pressure value, and the obtained ratio is exponentially operated to obtain the SF6 gas pressure compensation coefficient. The purpose of the exponential operation is to simulate the nonlinear relationship between the gas insulation strength and the pressure change, so that the compensation result more accurately reflects the actual electrical characteristic changes. At the same time, the vacuum degree inside the GIS equipment is compensated, and the real-time vacuum degree value of the vacuum circuit breaker is obtained by using the vacuum degree sensor. The collected data is processed by a digital low-pass filtering method to remove high-frequency noise and obtain the filtered vacuum degree value. Low-pass filtering is achieved by methods such as recursive mean filtering or IIR filtering to ensure that the filtered vacuum degree value is closer to the actual situation. The filtered vacuum degree value is inversely proportional to the rated vacuum degree value, and the obtained result is squared to obtain the vacuum degree compensation coefficient. The role of square operation is to enhance the influence of vacuum degree on electric field distribution, so that the compensation amount when vacuum degree decreases is more significant, and improve the fault identification accuracy of GIS equipment under vacuum insulation change. Considering the influence of ambient temperature on the insulation state of GIS equipment, a temperature sensor is introduced to collect the external ambient temperature, and based on this, the SF6 gas pressure compensation coefficient and vacuum compensation coefficient are temperature corrected. Since the pressure of SF6 gas changes with temperature, and the insulation characteristics of the vacuum interrupter are also affected by temperature, when calculating the comprehensive compensation coefficient, correction is made according to the temperature change trend. The correction method uses a temperature sensitive function to adjust the compensation coefficient so that it can be adaptively adjusted with the change of temperature to obtain the comprehensive compensation coefficient. The zero-sequence current component is decomposed in phase sequence, split into positive sequence, negative sequence and zero sequence components, and multiplied with the comprehensive compensation coefficient by complex operation to ensure that the compensated current value can correctly reflect the influence of SF6 gas pressure and vacuum degree changes in amplitude and phase, and obtain the compensated zero-sequence current value, reflecting the zero-sequence current characteristics of GIS equipment under different pressure and vacuum conditions. Similarly, the negative sequence current component is decomposed in phase sequence, and after the components are separated, they are multiplied by the comprehensive compensation coefficient to correct the errors caused by changes in SF6 gas pressure and vacuum degree, and finally the compensated negative sequence current value is obtained.

[0025] S3, calculate the amplitude ratio and phase angle difference between the metal shell current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain the fault judgment threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection;

[0026] It should be noted that the compensated zero-sequence current value and the compensated negative-sequence current value are orthogonally decomposed to extract the fundamental wave vectors of the metal shell current and the internal conductor current. Orthogonal decomposition is to convert the time domain signal into a frequency domain vector so as to more intuitively analyze the amplitude and phase relationship of different current components. The first fundamental wave vector of the metal shell current and the second fundamental wave vector of the internal conductor current are extracted, which represent the current characteristics of the metal shell and the internal conductor of the GIS equipment at the fundamental frequency respectively. The modulus of the first fundamental wave vector is divided by the modulus of the second fundamental wave vector to obtain the amplitude ratio of the metal shell current to the internal conductor current. The amplitude ratio is an important parameter for identifying the fault state, because under normal operation, the amplitude of the metal shell current is usually much smaller than the internal conductor current, and when a ground fault or insulation abnormality occurs, the metal shell current will increase significantly, resulting in a significant change in the amplitude ratio. By calculating the amplitude ratio, it is preliminarily judged whether the GIS equipment is in an abnormal state. At the same time, the phase angle difference between the metal shell current and the internal conductor current is calculated to analyze the relative phase relationship between them. The calculation of the phase angle difference is based on the difference in the argument between the fundamental wave vector of the metal shell current and the fundamental wave vector of the internal conductor current. This angle reflects the phase synchronization or offset between the shell current and the internal conductor current. Under normal circumstances, due to the design characteristics of the GIS equipment, the phase angle difference between the metal shell current and the internal conductor current is kept within a certain range. When a fault occurs, the phase angle difference will be significantly offset due to the influence of short circuit, leakage current or other abnormal factors. By calculating the phase angle difference, the normal state and the fault state are distinguished. The amplitude ratio and the phase angle difference are statistically analyzed to extract the characteristic information of the normal state and the fault state. Through a large amount of historical operation data or experimental data, the clustering algorithm is used to find the characteristic clustering center of the amplitude ratio and the phase angle difference under normal operation and fault state, and form a set of characteristic value ranges for fault determination. The amplitude ratio and phase angle difference data are classified by using methods such as K-means clustering or Gaussian mixture model to find the statistical distribution difference between the normal operation point and the abnormal state point, and form a classification result with practical reference value. Based on the characteristic clustering center, the amplitude ratio threshold range and the phase angle difference threshold range are determined so that they can be used for fault determination in actual operation. In order to improve the accuracy of judgment, the Bayesian probability statistics method is used to calculate the probability of fault occurrence in different threshold intervals. The application of Bayesian statistics calculates the possibility of faults within a specific amplitude ratio and phase angle difference range through prior probability and posterior probability, forming a fault judgment threshold based on probability reasoning. If the real-time amplitude ratio and phase angle difference of the GIS equipment exceed the normal range and meet the characteristic interval of high fault probability, it is determined that the equipment is in a fault state and protective measures are taken in time. A three-level protection configuration system for GIS equipment is established based on the fault judgment threshold, including differential protection, impedance protection and overcurrent protection.Among them, differential protection is used to detect short circuit or insulation breakdown faults inside GIS equipment, and determines whether there is abnormal current flow based on the current difference between the metal shell current and the internal conductor current. Impedance protection is used to analyze the impedance characteristic changes of GIS equipment to determine whether there is a ground fault or external short circuit fault. This protection mechanism relies on calculating the ratio of current and voltage to determine the type and location of the fault. Overcurrent protection is used to monitor the overall current level of GIS equipment and trigger protection action when the current exceeds the safety threshold to prevent equipment damage or further deterioration of faults. The three-level protection configuration system effectively identifies different types of GIS faults through reasonable threshold settings and logical judgments, and triggers corresponding protection actions according to the severity of the fault. Differential protection is used for fast protection inside GIS equipment, responding and removing faults within milliseconds; impedance protection is used to identify external line faults or ground faults and provide an additional layer of protection; overcurrent protection is the final safety line, providing the last protection when other protections fail to respond in time.

[0027] The first-level differential protection unit is constructed based on the fault judgment threshold to ensure that the GIS equipment can quickly identify and remove the fault when a short circuit or insulation fault occurs inside. The principle of differential protection is to measure the current of the incoming and outgoing lines of the GIS equipment based on the current transformer, and to determine whether there is an internal short circuit or abnormal current flow by calculating the internal current difference. In this process, the differential starting current threshold is set, which is used to determine whether there is an abnormal differential current inside the GIS and to ensure that the small unbalanced current during normal operation will not trigger the protection action by mistake. The differential braking coefficient is defined to handle the large current situation under external short circuit or non-fault state, and to prevent the asymmetric current caused by external faults from causing false operation. The first-level protection action time is set, which determines the response speed of the differential protection, usually at the millisecond level, so as to quickly isolate the fault point when a serious fault occurs. By setting the above parameters, the differential protection configuration parameters are formed for the first-level protection of the GIS equipment. The second-level impedance protection unit is constructed based on the fault judgment threshold to enhance the detection capability of the GIS equipment for external faults. The basic principle of impedance protection is to use the ratio of current to voltage to determine the location and nature of the fault. Therefore, the impedance protection range is set, that is, the impedance threshold of the protection area is defined to ensure that when a fault occurs in the GIS equipment and its connected lines, the fault is accurately identified and the protection action is triggered. At the same time, the impedance protection sensitivity angle is defined, which is used to distinguish between the normal load operation state and the fault state, and to ensure that the protection unit will not be falsely triggered due to normal fluctuations in system operation parameters. In order to avoid conflicts with the first-level protection, the second-level protection action time is set, which is slightly longer than the differential protection action time to ensure that when the differential protection fails to identify the fault in time, the impedance protection provides a supplementary protection function. Through the above configuration, the impedance protection configuration parameters are formed for the second-level protection of the GIS equipment. The third-level overcurrent protection unit is constructed based on the fault judgment threshold to ensure that the necessary protection action is performed when the current exceeds the limit. Overcurrent protection is used to deal with severe short circuits, equipment damage or line overload. Therefore, the overcurrent protection starting current is set to ensure that the protection mechanism can be triggered in time when the current exceeds the safety range. At the same time, in order to avoid false triggering due to short-term current fluctuations, the overcurrent protection return coefficient is set, that is, after the current returns to normal levels, the protection action should be able to automatically reset. In order to ensure the time coordination of the three-level protection, the third-level protection action time is defined, which is usually the longest time, to ensure that it is only triggered when both the differential protection and the impedance protection fail to act in time, providing the final safety line. By setting the above parameters, the overcurrent protection configuration parameters are formed for the third-level protection of GIS equipment. The differential protection configuration parameters, impedance protection configuration parameters and overcurrent protection configuration parameters are coordinated and calculated in time to ensure that the timing coordination relationship of each level of protection is reasonable.Taking into account the action time of different protection units, the coverage of the protection area, and the occurrence of false triggering, the triggering logic of the protection action is optimized through the timing coordination algorithm to ensure that the protection system can be executed in a predetermined order under different types of fault conditions to avoid the problem of false protection triggering or response delay. Through timing optimization, a three-level protection timing coordination relationship is formed. The timing coordination relationship of the three-level protection is input into the protection logic matrix, and the blocking conditions and accelerated action conditions of each level of protection are determined by logical operations. The blocking conditions are used to prevent unnecessary protection actions, such as avoiding false triggering of protection units when the system operates normally but there are short-term fluctuations; and the accelerated action conditions are used to shorten the protection action time when the fault is serious or lasts for a long time, so as to ensure that the GIS equipment can quickly isolate the fault point. In this process, the protection logic relationship is established through the AND gate (AND) and OR gate (OR) logical combination operations, so that different protection units can work together and respond correctly in different situations. Through logical calculation, the blocking conditions and accelerated action conditions of each level of protection are obtained. The protection start logic judgment criteria are established based on the blocking conditions and accelerated action conditions to ensure that the three-level protection is triggered according to the predetermined logic. Comprehensively consider the factors such as fault judgment threshold, protection action time, logical operation results and equipment operation status, and determine the final execution strategy of the protection system through a series of logical judgment processes. In this way, it is ensured that GIS equipment can be identified in time when a fault occurs, and appropriate protection measures can be taken to form a complete three-level protection configuration system.

[0028] S4, input the three-level protection configuration system into the digital signal processor to perform real-time monitoring, and obtain the action instructions and fault information of the hierarchical protection.

[0029] Specifically, the parameter matrix of the three-level protection configuration system is loaded into the FLASH memory of the digital signal processor to ensure that the protection algorithm can quickly access relevant parameters during operation. The storage of the parameter matrix includes key data such as the setting values ​​of differential protection, impedance protection and overcurrent protection, timing coordination relationship and logic control rules. During the storage process, the parameters are checked to ensure the integrity and accuracy of the data, so as to avoid the impact of storage errors on subsequent calculations. At the same time, in order to ensure the real-time performance of the system and the stability of the data, the FLASH memory is periodically refreshed to update the protection parameters and ensure the optimal adaptation of the protection configuration under different operating conditions. After the parameter matrix is ​​successfully loaded, the metal shell current and internal conductor current of the GIS equipment are sampled in real time, and the sampling data sequence is obtained. In order to ensure the sampling accuracy, a high-speed analog-to-digital converter (ADC) is used to collect the current signal at a fixed sampling rate, and the sampling rate is set to more than several kilohertz to capture the rapid current changes that occur during the operation of the GIS equipment. At the same time, the sampled signal is pre-filtered, such as low-pass filtering to remove high-frequency noise, or sliding average filtering to smooth the data sequence. After completing the signal preprocessing, the sampled data sequence is obtained and input into the data cache inside the DSP. Based on the sampling data sequence, the current difference of differential protection, the impedance value of impedance protection and the total current value of overcurrent protection are calculated respectively, and the calculation results are compared with the setting values ​​of each level of protection to determine whether the protection criteria are met. In the calculation of differential protection, the sampled GIS inlet and outlet currents are used for differential operation, and the differential current value at the current moment is calculated and compared with the preset differential start threshold. If it exceeds the threshold, the judgment signal of differential protection is triggered. At the same time, in order to prevent false triggering, the braking current is calculated, and the protection judgment is made according to the braking characteristic curve to ensure that the protection action is triggered only when a real internal fault occurs. In the impedance protection calculation, the equivalent impedance of the GIS equipment is calculated using the real-time sampled current and voltage data, and compared with the set impedance protection range. If the impedance value falls within the protection range, the judgment signal of impedance protection is triggered. In order to improve the sensitivity, the phase angle of the impedance is calculated to determine whether it falls into the sensitive angle range of the impedance protection, thereby further ensuring the accuracy of the judgment. In the overcurrent protection calculation, the total current value is obtained by summing the amplitudes of all phase currents and comparing it with the starting current of the overcurrent protection. If it exceeds the threshold, the judgment signal of the overcurrent protection is triggered. When the trigger signal of the protection judgment is generated, the timer is used for timing control to ensure that each level of protection is executed according to the preset action time. The timer counts the trigger signal, and after the preset protection action delay is reached, the corresponding protection action is triggered through the timer interrupt service program.The function of the timer is to achieve the time coordination of hierarchical protection. For example, when an internal fault occurs, the differential protection can respond quickly. If the differential protection fails to act, the impedance protection will act in a short time. If the impedance protection is not triggered, the overcurrent protection will be used to cut off the protection after a longer time. In the timer interrupt service program, the state of the trigger signal is constantly checked, and logical judgment is made according to the protection logic matrix to ensure that the protection system is executed in a predetermined logical order. After the action instruction of the hierarchical protection is generated, the protection signal is output through the GPIO interface of the DSP to control the tripping of the circuit breaker of the GIS equipment, and fault information is generated and the fault event is recorded. Using the 32-bit status word encoding method of the DSP, key information such as the time of fault occurrence, fault duration, fault phase, action protection type and protection action time are packaged and stored in the event storage unit for subsequent fault analysis and operation and maintenance management. Among them, the time of fault occurrence is recorded by the high-precision clock inside the DSP to ensure the accuracy of the time information, and the fault duration is obtained by calculating the difference between the trigger time and the recovery time. The fault phase is used to indicate in which phase or phases the fault occurs, the action protection type is used to distinguish whether the protection action is triggered by differential protection, impedance protection or overcurrent protection, and the protection action time records the time interval from the occurrence of the fault to the execution of the protection, so as to facilitate the subsequent optimization of the protection strategy.

[0030] The fault information is checked by CRC (Cyclic Redundancy Check) and the data frame is encapsulated to ensure that the data is not disturbed during transmission. CRC check is an error detection method that detects and prevents errors caused by noise or data corruption during communication by adding redundant check codes at the end of the data frame. After generating the fault information, the protection system of the GIS equipment calculates the CRC check code of the fault data and formats and encapsulates the data frame according to the RS485 communication protocol. During the encapsulation process, the start flag, device address, data content, CRC check code and stop flag are added to ensure that the host computer can accurately parse the data. The encapsulated data is sent to the host computer monitoring system through the "UART (Universal Asynchronous Receiver Transmitter)" interface to achieve remote real-time monitoring and ensure that the fault information can be transmitted and recorded in time. After the host computer receives the real-time monitoring results, it performs statistical analysis on the hierarchical protection action instructions and fault information, especially key data such as the number of protection actions, action time and number of refusal to act. In order to avoid the influence of data fluctuations on the statistical results, the sliding window statistical method is used to process the above parameters. Sliding window statistics is to perform rolling analysis on data in a fixed-length time window. Each time new data is introduced, the earliest data point is removed to maintain the timeliness of the data. Within the sliding window, the number of protection actions of GIS equipment, the action time of each level of protection, and the number of refusal to act are calculated, and a two-dimensional feature vector is constructed, which contains the time characteristics and reliability characteristics of the equipment protection action. A fuzzy rule base is constructed based on the two-dimensional feature vector to analyze the protection action characteristics of GIS equipment. The establishment of the fuzzy rule base is based on expert experience and historical data analysis, including the nonlinear mapping relationship between protection action frequency and protection reliability. In order to ensure the accuracy of fuzzy reasoning, the input variables in the fuzzy rule base, namely the domain of action frequency and reliability, are divided into seven fuzzy subsets, representing different protection status levels. In order to ensure the continuity and computability of the fuzzy subsets, the trapezoidal membership function is calculated for each subset, where the membership function is used to represent the degree of belonging of a certain input variable in a specific subset. By calculating the trapezoidal membership functions of different subsets, a complete fuzzy relationship matrix is ​​constructed to establish the fuzzy mapping relationship between protection action frequency and reliability. Mamdani fuzzy reasoning operation is performed based on the fuzzy relationship matrix to derive the specific adjustment value of the protection parameter. Mamdani fuzzy reasoning is a reasoning method based on a fuzzy rule base, and its main process includes fuzzification, rule matching, fuzzy reasoning calculation and defuzzification.In the fuzzification stage, the input two-dimensional feature vector is converted into fuzzy variables and matched with the fuzzy rule base; in the rule matching stage, the degree of association between the input variables and each fuzzy subset is determined based on the fuzzy relationship matrix; in the fuzzy reasoning calculation stage, fuzzy logic operations are applied to comprehensively evaluate the input data to obtain the fuzzy output of the protection parameter adjustment; in the defuzzification stage, the results of the fuzzy reasoning calculation are converted into specific protection parameter adjustment values ​​for subsequent adaptive optimization. After obtaining the specific adjustment values ​​of the protection parameters, the sensor data is used to evaluate the equipment health in combination with the environmental parameters of the GIS equipment to achieve adaptive optimization. The real-time data of the SF6 gas pressure sensor, vacuum sensor, and temperature and humidity sensor are collected, and the deviation is calculated from their rated standard values ​​to obtain the health status index of the equipment. The deviation of SF6 gas pressure reflects the insulation state of the GIS equipment, the deviation of vacuum indicates the working condition of the vacuum circuit breaker, and the deviation of temperature and humidity is used to evaluate whether the environmental changes inside the GIS may affect the long-term reliability of the equipment. By calculating these deviation values, the equipment health index of the GIS equipment is obtained and used as an important basis for optimizing the protection strategy. The equipment health index is segmented to form an interval mapping relationship of different health levels. The equipment health index is divided into several health levels, such as "normal", "mild abnormality", "moderate abnormality" and "severe abnormality", so that different protection strategies can be adopted in different health states. Based on the results of segmented processing, adaptive optimization results are generated, that is, the protection parameters are dynamically adjusted under different equipment health states. For example, when the equipment is in good health, the protection parameters maintain a high sensitivity, and when the equipment has a slight abnormality, the protection setting value is appropriately relaxed to avoid false triggering. In the case of severe abnormality, the rapidity of protection is improved to ensure the safety of GIS equipment.

[0031] In one example, the zero-sequence component and negative-sequence component decoupling analysis is performed on the metal shell current and the internal conductor current of the GIS equipment to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model, including:

[0032] Perform Fourier transform on the metal shell current and internal conductor current of GIS equipment to obtain the metal shell current spectrum and internal conductor current spectrum;

[0033] Perform symmetrical component transformation matrix operation on the metal shell current spectrum and the internal conductor current spectrum to obtain zero-sequence current component and negative-sequence current component;

[0034] Based on the zero-sequence current component, the zero-sequence impedance equation is constructed, and the metal shell grounding impedance and the internal conductor grounding impedance are introduced to obtain the node admittance matrix of the zero-sequence network.

[0035] The negative-sequence impedance equation is constructed based on the negative-sequence current component, and the mutual inductance impedance between the metal shell and the internal conductor is introduced to obtain the node admittance matrix of the negative-sequence network.

[0036] The network equation of the zero-sequence equivalent circuit is solved by the node voltage method according to the node admittance matrix of the zero-sequence network to obtain the zero-sequence equivalent circuit model, and the network equation of the negative-sequence equivalent circuit is solved by the node voltage method according to the node admittance matrix of the negative-sequence network to obtain the negative-sequence equivalent circuit model.

[0037] In this example, the metal shell current and internal conductor current of the GIS equipment are sampled in the time domain to obtain its instantaneous current data. Assume that the sampled metal shell current signal is , the internal conductor current signal is ,in Represents time. Since the current signal contains multiple frequency components, it is subjected to Fourier transform to obtain spectrum information. The definition of Fourier transform is as follows:

[0038]

[0039] in, is the current component in the frequency domain, is the current signal in the time domain, is the frequency, is an imaginary unit. The metal shell current is analyzed by fast Fourier transform. and internal conductor current After transformation, the spectrum of the metal shell current is obtained respectively and the spectrum of the internal conductor current , these two spectra contain the harmonic components of the current signal. Symmetrical component transformation is performed on the metal shell current spectrum and the internal conductor current spectrum to separate the zero-sequence and negative-sequence current components. The basic principle of symmetrical component transformation is to convert the three-phase current into zero-sequence, positive-sequence and negative-sequence components. For a three-phase system, the three-phase current is defined as , then the symmetric component transformation matrix is ​​expressed as:

[0040]

[0041] in, is the zero sequence component, is the positive sequence component, is the negative sequence component, and is the phase rotation factor, defined as . In the current spectrum of the metal shell and internal conductor current spectrum After applying this transformation matrix, the corresponding zero-sequence current is extracted and negative sequence current , these two components are used for the subsequent modeling of zero-sequence network and negative-sequence network respectively. Based on the calculated zero-sequence current component , construct the zero-sequence impedance equation and introduce the metal shell grounding impedance and internal conductor ground impedance , and obtain the node admittance matrix of the zero-sequence network. Assume that the zero-sequence network of the GIS equipment is equivalent to a The admittance matrix of a power system with nodes is expressed as:

[0042]

[0043] Among them, the matrix elements Representative Node and The zero-sequence admittance value between the nodes is determined by the zero-sequence impedance Calculated, that is:

[0044]

[0045] At the same time, based on the negative sequence current component , construct the negative sequence impedance equation, and introduce the mutual inductance impedance between the metal shell and the internal conductor , we get the node admittance matrix of the negative sequence network. Similar to the zero sequence network, the admittance matrix of the negative sequence network is It is expressed as:

[0046]

[0047] Among them, negative sequence admittance Negative sequence impedance The calculation formula is similar to that of the zero-sequence network, but the mutual inductance impedance is taken into account. The impact of

[0048]

[0049] After constructing the node admittance matrix of the zero-sequence and negative-sequence networks, the node voltage method is applied to solve the network equations to obtain the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model. The basic form of the node voltage equation is:

[0050]

[0051]

[0052] in, and are the node voltage vectors of the zero-sequence and negative-sequence networks, respectively, and and are the zero-sequence and negative-sequence current source vectors, respectively. By solving these linear equations, the zero-sequence voltage and negative-sequence voltage of each node are obtained, and used to calculate the current distribution of GIS equipment under different operating conditions. For example, suppose a single-phase grounding fault occurs in a GIS equipment. In this fault condition, the zero-sequence current component Significantly increased, and since negative sequence current is mainly related to asymmetrical faults, By solving the node voltage equation, the voltage drop of each node is calculated, and the specific location and type of the fault are determined by combining the distribution characteristics of the zero-sequence and negative-sequence currents.

[0053] In one example, SF6 gas pressure compensation and vacuum degree compensation operations are performed based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value, including:

[0054] The real-time pressure value collected by the SF6 gas pressure sensor is subjected to sliding window filtering to obtain a filtered pressure value, and the ratio of the filtered pressure value to the standard atmospheric pressure value is subjected to power operation to obtain the SF6 gas pressure compensation coefficient;

[0055] The real-time vacuum value collected by the vacuum sensor is subjected to digital low-pass filtering to obtain a filtered vacuum value, and the filtered vacuum value is squared with the inverse ratio of the rated vacuum value to obtain a vacuum compensation coefficient;

[0056] Based on the ambient temperature value collected by the temperature sensor, the SF6 gas pressure compensation coefficient and the vacuum compensation coefficient are temperature corrected to obtain a comprehensive compensation coefficient;

[0057] The zero-sequence current component of the zero-sequence equivalent circuit model is decomposed into phase sequence, and a complex multiplication operation is performed with the comprehensive compensation coefficient to obtain the compensated zero-sequence current value;

[0058] The negative-sequence current component of the negative-sequence equivalent circuit model is decomposed in phase sequence and multiplied by a complex number with the comprehensive compensation coefficient to obtain the compensated negative-sequence current value.

[0059] In this example, the real-time pressure values ​​collected by the SF6 gas pressure sensor are filtered to remove short-term fluctuations and sensor noise. The sliding window filtering method is used to smooth the data by taking the average or weighted average of the pressure values ​​over a period of time, thereby reducing the instantaneous error. Assume that at time At, the original sampling value of SF6 gas pressure is , the sliding window size is set to , then the pressure value after filtering The calculation is as follows:

[0060]

[0061] in, is the filtered SF6 gas pressure, is the window length, Representing the past The pressure value at the moment. Based on the filtered pressure value, the SF6 gas pressure compensation coefficient is calculated to correct the influence of gas pressure change on electrical parameters. The compensation coefficient is calculated based on the filtered pressure value. With standard atmospheric pressure The ratio between them is calculated by exponentiation, that is:

[0062]

[0063] in, is the SF6 gas pressure compensation coefficient, is the standard atmospheric pressure, is the compensation coefficient index, which is used to adjust the sensitivity of the compensation curve. The change of SF6 gas pressure inside the GIS equipment will affect the insulation performance, so the current calculation is corrected by the compensation coefficient. At the same time, for the vacuum circuit breaker in the GIS equipment, its working state is affected by the vacuum degree, so the real-time vacuum value collected by the vacuum sensor is filtered to remove measurement noise and short-term fluctuations. The digital low-pass filtering method is used to retain the low-frequency components of the signal and attenuate the high-frequency noise. Assume that the vacuum value of the original sampling is , the vacuum value after filtering It is expressed as:

[0064]

[0065] in, is the filter coefficient, range , takes a value close to 1 to maintain a smooth change, is the filtered value at the last moment. Calculate the vacuum degree compensation coefficient, which is calculated by the vacuum degree after filtering. Rated vacuum The inverse relationship between is calculated and squared to enhance the compensation effect in low vacuum conditions:

[0066]

[0067] in, is the vacuum compensation coefficient, is the rated vacuum value. When the vacuum decreases, the insulation capacity of the GIS circuit breaker will decrease, so the compensation coefficient is used to make corresponding corrections to the current measurement results. In order to improve the compensation accuracy, considering the impact of ambient temperature on GIS equipment, the ambient temperature measured by the temperature sensor is introduced. , and based on it, correct the SF6 gas pressure compensation coefficient and vacuum compensation coefficient to obtain the final comprehensive compensation coefficient The temperature compensation is corrected by linear or exponential relationship, and the temperature correction coefficient is defined. for:

[0068]

[0069] in, is the standard temperature, is the temperature compensation coefficient. The final comprehensive compensation coefficient The calculation is as follows:

[0070]

[0071] in, As a correction factor, it is used to compensate for the influence of SF6 gas pressure, vacuum degree and ambient temperature. Applied to the compensation calculation of zero-sequence current and negative-sequence current. The zero-sequence current component of the zero-sequence equivalent circuit model Perform phase sequence decomposition to extract its orthogonal components. Assume that the zero sequence current is in complex form:

[0072]

[0073] in, is the real part of the zero-sequence current, is the imaginary part of the zero-sequence current. Perform complex multiplication to obtain the compensated zero-sequence current :

[0074]

[0075] Similarly, for the negative sequence current component of the negative sequence equivalent circuit model , the compensation calculation process is the same, assuming the negative sequence current is:

[0076]

[0077] Then the compensated negative sequence current The calculation is as follows:

[0078]

[0079] In one example, the amplitude ratio and phase angle difference between the metal casing current and the internal conductor current are calculated based on the compensated zero-sequence current value and the compensated negative-sequence current value, the fault judgment threshold is obtained, and a three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established, including:

[0080] orthogonally decomposing the compensated zero-sequence current value and the compensated negative-sequence current value to obtain a first fundamental wave vector of the metal casing current and a second fundamental wave vector of the internal conductor current;

[0081] Dividing the modulus value of the first fundamental wave vector by the modulus value of the second fundamental wave vector, to obtain an amplitude ratio of the metal shell current to the internal conductor current;

[0082] The phase angle difference between the metal shell current and the internal conductor current is obtained by performing phase calculation based on the difference in the argument between the metal shell current fundamental wave vector and the internal conductor current fundamental wave vector.

[0083] Perform statistical analysis on the amplitude ratio and phase angle difference to obtain the characteristic clustering centers of normal state and fault state;

[0084] The amplitude ratio threshold range and the phase angle difference threshold range are determined according to the feature clustering center, and the fault occurrence probability of different threshold intervals is calculated by the Bayesian probability statistics method to obtain the fault judgment threshold;

[0085] A three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established based on the fault judgment threshold.

[0086] In this example, the zero-sequence current value after compensation is And the negative sequence current value after compensation Perform mathematical transformation to extract the fundamental wave vectors of the metal shell current and the internal conductor current. and is the current component expressed as a complex number, where represents the real and imaginary parts of the zero-sequence current, Represents the real and imaginary parts of the negative sequence current. Through orthogonal decomposition, the first fundamental wave vector of the metal casing current is extracted and the second fundamental wave vector of the internal conductor current , the specific calculation method is as follows:

[0087]

[0088]

[0089] in, and Im represent the real part and imaginary part of the complex number, respectively. This decomposition method ensures that the obtained fundamental wave vector truly reflects the fundamental wave components of the metal shell current and the internal conductor current. The amplitude ratio of the metal shell current and the internal conductor current is calculated to measure the relative magnitude relationship between the two. The calculation of the amplitude ratio is based on the modulus of the fundamental wave vector. Assume that the modulus of the first fundamental wave vector is , the modulus of the second fundamental wave vector is , then the amplitude ratio The calculation formula is as follows:

[0090]

[0091] in, represents the amplitude of the metal casing current, represents the amplitude of the internal conductor current. This ratio is used to distinguish between normal operating conditions and fault conditions. In normal conditions, the metal casing current is usually small, while in the event of a fault, the casing current will increase significantly, resulting in a significant change in the amplitude ratio. The phase angle difference between the metal casing current and the internal conductor current is calculated to evaluate the relative phase relationship between the two. Assume that the phase angle of the metal casing current fundamental wave vector is , the phase angle of the fundamental wave vector of the internal conductor current is , then the phase angle difference The calculation formula is:

[0092]

[0093] in, Represents the phase angle calculation of a complex number, namely:

[0094]

[0095] The phase angle difference is used to determine the fault type. Under normal circumstances, the phase relationship between the metal shell current and the internal conductor current is stable, but when a fault occurs, the phase angle will shift significantly. In order to determine the characteristics of the normal state and the fault state, the amplitude ratio is compared. and phase angle difference Perform statistical analysis on the data to identify its distribution characteristics under different operating conditions. By collecting a large amount of historical data under normal operation and fault conditions, cluster analysis methods (such as K-means clustering) are used to find the characteristic clustering centers of amplitude ratio and phase angle difference. Assume that the mean amplitude ratio under normal conditions is , the average amplitude ratio under fault condition is The average phase angle difference under normal conditions is The average phase angle difference under fault condition is , the feature cluster center is calculated by the following statistical formula:

[0096]

[0097]

[0098] in, and are the number of data samples in normal state and fault state respectively. After obtaining the feature cluster center, the amplitude ratio threshold range and the phase angle difference threshold range are determined, and the Bayesian probability statistics method is used to calculate the probability of fault occurrence in different threshold intervals. The basic formula of Bayesian statistics is as follows:

[0099]

[0100] in, Indicates the amplitude ratio The probability of failure in a given situation, Indicates that in the event of a fault the amplitude ratio The probability density of is the prior probability of failure, is the overall distribution probability of the amplitude ratio. By calculating the fault probability within different amplitude ratios and phase angle differences, an accurate fault judgment threshold is formed. Based on the fault judgment threshold, a three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established. Among them, differential protection is used to quickly detect short-circuit faults inside GIS equipment. Based on the calculated amplitude ratio and phase angle difference threshold, the differential starting current threshold is set. , and its calculation formula is:

[0101]

[0102] in, Impedance protection is used to detect external line faults and set the impedance protection range. :

[0103]

[0104] in, The overcurrent protection is used to monitor the overall current level of the GIS equipment and set the overcurrent protection starting current. :

[0105]

[0106] in, Through the above calculations, a complete three-level protection configuration system is formed to ensure that GIS equipment correctly triggers the corresponding protection mechanism under different types of fault conditions, thereby improving the safety and stability of the power system.

[0107] In one example, a three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established based on the fault judgment threshold, including:

[0108] The first-level differential protection unit is constructed based on the fault criterion threshold, and the differential starting current threshold, differential braking coefficient and first-level protection action time are set to obtain the differential protection configuration parameters;

[0109] Based on the fault judgment threshold, a second-level impedance protection unit is constructed, and the impedance protection range, impedance protection sensitivity angle, and second-level protection action time are set to obtain impedance protection configuration parameters;

[0110] Based on the fault judgment threshold, the third-level overcurrent protection unit is constructed, the overcurrent protection starting current, the overcurrent protection return coefficient and the third-level protection action time are set, and the overcurrent protection configuration parameters are obtained;

[0111] Perform timing coordination calculation on the differential protection configuration parameters, impedance protection configuration parameters and overcurrent protection configuration parameters to obtain the timing coordination relationship of the three-level protection;

[0112] Input the timing coordination relationship of the three-level protection into the protection logic matrix, and obtain the blocking conditions and acceleration action conditions of each level of protection through AND gate and OR gate logic combination operations;

[0113] The protection start logic criterion is established according to the locking conditions and acceleration action conditions to obtain a three-level protection configuration system.

[0114] In this example, a first-level differential protection unit is established, which is used to quickly detect short circuits or insulation faults inside GIS equipment. The basic principle of differential protection is to calculate the difference between the currents at both ends of the GIS equipment and determine whether to trigger the protection action based on the comparison between the difference and the setting threshold. Assume that the incoming line current of the GIS equipment is , the outgoing current is , then the differential current The calculation formula is:

[0115]

[0116] In order to prevent false operation caused by external faults or CT (current transformer) measurement errors, a differential starting current threshold is introduced As the minimum current value for triggering protection, it also defines the differential braking coefficient , which is used to adjust the sensitivity of the protection. The calculation of the differential braking coefficient depends on the operating status of the GIS equipment and is expressed as:

[0117]

[0118] And set the first level protection action time ,when When the braking criteria are met, the differential protection will Triggered within seconds. Finally, these parameters are combined to obtain the differential protection configuration parameters for fast fault response of GIS equipment. In addition to the differential protection, a second-level impedance protection unit is established, which is mainly used to detect external line faults, especially line grounding faults or phase-to-phase short circuit faults. The basic principle of impedance protection is to calculate the equivalent impedance of the fault point and compare it with the preset impedance threshold. The impedance calculation formula is:

[0119]

[0120] in, is the equivalent impedance of the fault point, To measure voltage, To measure current. To improve the accuracy of fault detection, set the impedance protection range , which is the impedance threshold of the protection area, and also defines the impedance protection sensitivity angle , used to distinguish between normal operation and fault conditions. The calculation method of the sensitivity angle is:

[0121]

[0122] In addition, set the second level protection action time To ensure that the impedance protection can respond in time when the differential protection fails to operate. Combine the impedance range, sensitivity angle and protection time parameters to obtain the impedance protection configuration parameters. At the same time, a third-level overcurrent protection unit is established to detect overload or short-circuit faults of GIS equipment. The basic principle of overcurrent protection is based on the monitoring of line current amplitude. Assume that the measured current of GIS equipment is , then the overcurrent protection starting current It is expressed as:

[0123]

[0124] in, is the rated current of the GIS equipment, is the overcurrent protection setting coefficient. In order to improve the stability of protection, the overcurrent protection return coefficient is defined , that is, when the current drops to When the protection is below, the protection will automatically reset. Set the third level protection action time To ensure that when both differential protection and impedance protection fail to operate, overcurrent protection can provide the final safety line. Combine these parameters to obtain the overcurrent protection configuration parameters. After completing the parameter setting of the three-level protection unit, perform timing coordination operations to ensure that each level of protection is executed in a reasonable time sequence. The core of timing coordination is to determine the priority relationship of protection actions, following the following principles:

[0125]

[0126] in, is the differential protection action time, is the impedance protection action time, is the overcurrent protection action time. In order to optimize the timing coordination, calculate the protection time margin :

[0127]

[0128] This margin ensures that if the differential protection fails to operate, the impedance protection can respond in time. At the same time, the overcurrent protection operation time Appropriate delay is required to avoid false operation. After timing optimization calculation, the timing coordination relationship of the three-level protection is obtained. The timing coordination relationship is input into the protection logic matrix, and the protection locking and acceleration control are performed using logical operations. , and They represent the action signals of differential protection, impedance protection and overcurrent protection respectively, and the protection logic relationship is expressed as:

[0129]

[0130]

[0131] in, Represents a logical OR operation. Represents the logical AND operation, and Respectively represent the non-operating state of differential protection and impedance protection. Through these logical relationships, the blocking conditions and accelerated action conditions of each level of protection are obtained to ensure that the GIS equipment can correctly trigger the corresponding protection mechanism under different types of fault conditions. After completing the construction of the protection logic matrix, the protection start logic criterion is established to ensure the reliability of the protection system. The protection start logic is set based on the fault criterion threshold. Suppose the fault current threshold is , then the protection start condition is expressed as:

[0132]

[0133] This logic criterion ensures that when the fault current exceeds the threshold, at least one protection unit can trigger the protection action. Through the above calculation and logic operation, a three-level protection configuration system is formed.

[0134] In one example, the three-level protection configuration system is input into a digital signal processor for real-time monitoring to obtain the action instructions and fault information of the hierarchical protection, including:

[0135] The parameter matrix of the three-level protection configuration system is loaded into the FLASH memory of the digital signal processor, and the metal shell current and the internal conductor current are sampled to obtain a sampling data sequence;

[0136] Based on the sampling data sequence, the current difference of the differential protection, the impedance value of the impedance protection and the total current value of the overcurrent protection are calculated respectively, and compared with the setting values ​​of each level of protection to obtain the trigger signal of the protection criterion;

[0137] The trigger signal of the protection criterion starts the timer counting, and the timing is controlled through the timing interrupt service program to obtain the action instruction of the hierarchical protection;

[0138] The action instructions of the hierarchical protection are output through the GPIO interface of the DSP to generate a 32-bit status word including the fault occurrence time, fault duration, fault phase, action protection type and protection action time to obtain the fault information.

[0139] In this example, the parameter matrix of the three-level protection configuration system is loaded into the FLASH memory of the digital signal processor to ensure that the parameter integrity is maintained after the device is powered on or reset. The stored parameters include the starting current threshold of the differential protection , Braking coefficient and action time , impedance protection impedance threshold and sensitive angle , and the starting current of the overcurrent protection and return coefficient . These parameters are stored in matrix form, such as:

[0140]

[0141] Each row corresponds to the parameters of a protection unit, which are stored in the FLASH memory with a fixed address so that the DSP can read it quickly during operation. and internal conductor current Perform high-speed sampling to obtain a sampling data sequence. Assume that the sampling period is , then at each sampling moment , the sampling current is expressed as:

[0142]

[0143] These sampled values ​​are stored in the DSP RAM cache and processed by fast Fourier transform or sliding window mean filtering to remove the influence of high-frequency noise and power frequency fluctuations. Based on the sampled data sequence, the current difference of differential protection, the impedance value of impedance protection and the total current value of overcurrent protection are calculated respectively. The calculation is as follows:

[0144]

[0145] And with the set value Compare, if satisfied , then a differential protection trigger signal is generated Secondly, the impedance value of the impedance protection By voltage and current The calculation formula is as follows:

[0146]

[0147] in, is the sampled GIS voltage signal, is the operating current of GIS. , and the phase angle satisfies , then an impedance protection trigger signal is generated The total current of the overcurrent protection The calculation is as follows:

[0148]

[0149] And with the set overcurrent starting current For comparison, if , then the over-current protection signal is triggered After the trigger signal of the protection criterion is generated, the timer count is started to ensure the timing coordination of each level of protection. The high-precision timer inside the DSP is used to monitor the duration of the protection signal. Set the timer count value , when the count value exceeds the protection action time , then the corresponding protection instruction is triggered. Assume that the timer counting equation is as follows:

[0150]

[0151] if , the differential protection is triggered; if , the impedance protection is triggered; if , the overcurrent protection is triggered. After the timer count reaches the set time, the DSP executes the timing control and generates the action instruction of the hierarchical protection. Through the GPIO interface of the DSP, the protection action signal is output to the circuit breaker control module of the GIS equipment to complete the protection action. The GPIO output signal is defined as follows:

[0152]

[0153] Among them, the logical OR operation Ensure that as long as a protection signal is triggered, a control instruction can be sent to the trip unit of the GIS device. In order to record the fault information, the DSP generates a 32-bit status word, which contains the time when the fault occurred. , Fault duration , Fault phase , Action protection type And protection action time The 32-bit status word is encoded in the following format:

[0154]

[0155] The status word is stored in the non-volatile memory of the DSP and sent to the host computer via the UART or CAN bus for analysis by the operation and maintenance personnel.

[0156] In one example, the grounding protection method of high-voltage fully enclosed vacuum environmentally friendly GIS equipment also includes:

[0157] Perform CRC check and data frame encapsulation on the fault information, and send it to the host computer monitoring system through the UART interface according to the RS485 communication protocol to obtain real-time monitoring results;

[0158] Perform sliding window statistics on the protection action times, action time and refusal times of the hierarchical protection action instructions and fault information records in the real-time monitoring results to obtain a two-dimensional feature vector;

[0159] A fuzzy rule base is established based on two-dimensional feature vectors, and the domain of action frequency and reliability input variables in the fuzzy rule base is divided into seven fuzzy subsets. The trapezoidal membership function is calculated for each fuzzy subset to obtain a fuzzy relationship matrix.

[0160] Perform Mamdani fuzzy reasoning operation based on the fuzzy relationship matrix to obtain the specific adjustment value of the protection parameter;

[0161] Based on the specific adjustment values ​​of the protection parameters, the real-time data collected by the SF6 gas pressure sensor, vacuum sensor and temperature and humidity sensor are respectively calculated for deviation from their standard values ​​to obtain the equipment health index, which is then processed in sections to generate an adaptive optimization result.

[0162] In this example, the fault information is CRC-checked and encapsulated in a data frame. CRC (Cyclic Redundancy Check) is an algorithm used to detect data transmission errors. It generates a check code through polynomial division and performs remainder verification at the receiving end to determine whether an error occurs during data transmission. Assume that the fault information data frame is , the generating polynomial is , then the method for calculating the CRC check code is expressed as:

[0163]

[0164] in, is the CRC remainder, Select a standard polynomial (such as CRC-16-CCITT: ). Fault information data frame Contains original data And additional CRC checksum :

[0165]

[0166] The data frame is encapsulated according to the RS485 communication protocol and sent to the host computer monitoring system through the UART (Universal Asynchronous Receiver / Transmitter) interface. RS485 is a serial communication protocol that supports long-distance transmission and multi-node communication. Its data format includes start bit, data bit, parity bit and stop bit to ensure that data can be transmitted stably in a high-noise environment. Assume that the fault information data frame length is Bytes, the data transfer rate is bps (bits per second), then the data transmission time Calculated as:

[0167]

[0168] Among them, 10 means that each byte contains 1 start bit, 8 data bits and 1 stop bit. After the data frame is successfully transmitted to the host computer, the monitoring system performs CRC check on the received data and parses the fault information to obtain real-time monitoring results. The protection action times recorded in the hierarchical protection action instructions and fault information in the real-time monitoring results are , Protection action time and the number of rejections Perform sliding window statistics to obtain the historical behavior characteristics of the system. Sliding window statistics is a The protection actions are weighted to smooth short-term fluctuations and capture the long-term trend of the system. Suppose the number of protection actions in the sliding window is , the number of rejections is , then the sliding mean is calculated as follows:

[0169]

[0170] in, and Represent the sliding average of the number of protection actions and the number of refusal actions respectively. Based on this, a two-dimensional feature vector is constructed:

[0171]

[0172] The eigenvector is used to describe the overall reliability and response frequency of the protection system and is used as the input variable for subsequent fuzzy reasoning. A fuzzy rule base is established, and the domain of the input variable is divided into seven fuzzy subsets in order to fuzzily classify the operating status of the protection system. is the action frequency, is reliability, and its fuzzy subsets are expressed as:

[0173] Very low, Very low, Low, Medium, High, Very high, Very high

[0174] Very bad, Very bad, Poor, Average, Good, Very good, Excellent

[0175] For each fuzzy subset, calculate the trapezoidal membership function and , defined as follows:

[0176]

[0177] in, Represent the four boundary points of the trapezoidal function. Similarly, calculate The membership function of :

[0178]

[0179] After obtaining the fuzzy relationship matrix, Mamdani fuzzy reasoning operation is performed to calculate the specific adjustment value of the protection parameter through the minimum-maximum combination rule. :

[0180]

[0181] This calculation process is used to adjust the sensitivity and response time of the protection system to optimize the protection configuration. Based on the adjusted protection parameters , analyze the real-time data of SF6 gas pressure sensor, vacuum sensor and temperature and humidity sensor to calculate the health status of the equipment. Assume that the SF6 gas pressure is , vacuum degree is , temperature and humidity are , and their standard values ​​are , then calculate the device health index as follows:

[0182]

[0183] in, They are the weight coefficients of each sensor data, which are used to balance the impact of different factors on the health of the equipment. Health Index After the calculation is completed, segmentation processing is performed to generate adaptive optimization results. The specific segmentation definitions are as follows:

[0184]

[0185] in, Indicates that the device is running healthy. Immediate maintenance is required. The optimization results are returned to the GIS protection system to adjust the protection parameters and optimize the operation strategy, thereby improving the safety and operation efficiency of the equipment.

[0186] Reference Figure 2 This embodiment provides a grounding protection device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, including:

[0187] The decoupling analysis unit 1 is used to perform zero-sequence component and negative-sequence component decoupling analysis on the metal shell current and the internal conductor current of the GIS equipment to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model;

[0188] The compensation operation unit 2 is used to perform SF6 gas pressure compensation and vacuum degree compensation operations based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value;

[0189] The calculation unit 3 is used to calculate the amplitude ratio and phase angle difference between the metal shell current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain the fault judgment threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection;

[0190] The real-time monitoring unit 4 is used to input the three-level protection configuration system into the digital signal processor to perform real-time monitoring and obtain the action instructions and fault information of the hierarchical protection.

[0191] In this embodiment, for the specific implementation of each unit in the above device embodiment, please refer to the above method embodiment, which will not be repeated here.

[0192] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, device, article or method including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, device, article or method. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the presence of other identical elements in the process, device, article or method including the element.

[0193] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, characterized in that: The following steps are involved: The zero-sequence component and negative-sequence component decoupling analysis of the metal shell current and internal conductor current of the GIS equipment are carried out to obtain the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model; Based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model, SF6 gas pressure compensation and vacuum degree compensation operations are performed to obtain a compensated zero-sequence current value and a compensated negative-sequence current value; specifically comprising: performing sliding window filtering on the real-time pressure value collected by the SF6 gas pressure sensor to obtain a filtered pressure value, and performing power operation on the ratio of the filtered pressure value to the standard atmospheric pressure value to obtain an SF6 gas pressure compensation coefficient; performing digital low-pass filtering on the real-time vacuum degree value collected by the vacuum degree sensor to obtain a filtered vacuum degree value, and performing power operation on the ratio of the filtered pressure value to the standard atmospheric pressure value to obtain an SF6 gas pressure compensation coefficient. The inverse value of the degree value and the rated vacuum degree value is squared to obtain a vacuum degree compensation coefficient; the SF6 gas pressure compensation coefficient and the vacuum degree compensation coefficient are temperature corrected based on the ambient temperature value collected by the temperature sensor to obtain a comprehensive compensation coefficient; the zero-sequence current component of the zero-sequence equivalent circuit model is decomposed in phase sequence, and a complex multiplication operation is performed with the comprehensive compensation coefficient to obtain a compensated zero-sequence current value; the negative-sequence current component of the negative-sequence equivalent circuit model is decomposed in phase sequence, and a complex multiplication operation is performed with the comprehensive compensation coefficient to obtain a compensated negative-sequence current value; Calculate the amplitude ratio and phase angle difference between the metal casing current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain the fault criterion threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection; The three-level protection configuration system is input into a digital signal processor to perform real-time monitoring to obtain action instructions and fault information of the hierarchical protection.

2. The grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment according to claim 1 is characterized in that: The zero-sequence component and negative-sequence component decoupling analysis of the metal shell current and the internal conductor current of the GIS equipment is performed to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model, including: Perform Fourier transform on the metal shell current and internal conductor current of GIS equipment to obtain the metal shell current spectrum and internal conductor current spectrum; Performing a symmetrical component transformation matrix operation on the metal shell current spectrum and the internal conductor current spectrum to obtain a zero-sequence current component and a negative-sequence current component; A zero-sequence impedance equation is constructed based on the zero-sequence current component, and the metal shell grounding impedance and the internal conductor grounding impedance are introduced to obtain a node admittance matrix of the zero-sequence network; A negative-sequence impedance equation is constructed based on the negative-sequence current component, and the mutual inductance impedance between the metal shell and the internal conductor is introduced to obtain a node admittance matrix of the negative-sequence network; The network equation of the zero-sequence equivalent circuit is solved by the node voltage method according to the node admittance matrix of the zero-sequence network to obtain a zero-sequence equivalent circuit model, and the network equation of the negative-sequence equivalent circuit is solved by the node voltage method according to the node admittance matrix of the negative-sequence network to obtain a negative-sequence equivalent circuit model.

3. The grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment according to claim 1 is characterized in that: The amplitude ratio and phase angle difference between the metal casing current and the internal conductor current are calculated according to the compensated zero-sequence current value and the compensated negative-sequence current value, a fault criterion threshold is obtained, and a three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established, including: orthogonally decomposing the compensated zero-sequence current value and the compensated negative-sequence current value to obtain a first fundamental wave vector of the metal casing current and a second fundamental wave vector of the internal conductor current; Dividing the modulus of the first fundamental wave vector by the modulus of the second fundamental wave vector to obtain an amplitude ratio of the metal shell current to the internal conductor current; Performing phase calculation based on the argument difference between the fundamental wave vector of the metal shell current and the fundamental wave vector of the internal conductor current to obtain a phase angle difference between the metal shell current and the internal conductor current; Performing data statistical analysis on the amplitude ratio and the phase angle difference to obtain characteristic clustering centers of a normal state and a fault state; Determine the amplitude ratio threshold range and the phase angle difference threshold range according to the feature cluster center, and calculate the fault occurrence probability of different threshold intervals by Bayesian probability statistics method to obtain the fault judgment threshold; A three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established based on the fault criterion threshold.

4. The grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment according to claim 3 is characterized in that: The three-level protection configuration system of differential protection, impedance protection and overcurrent protection is established based on the fault criterion threshold, including: A first-level differential protection unit is constructed based on the fault criterion threshold, a differential starting current threshold, a differential braking coefficient and a first-level protection action time are set, and differential protection configuration parameters are obtained; Based on the fault criterion threshold, a second-level impedance protection unit is constructed, an impedance protection range, an impedance protection sensitivity angle, and a second-level protection action time are set, and impedance protection configuration parameters are obtained; Based on the fault criterion threshold, a third-level overcurrent protection unit is constructed, an overcurrent protection starting current, an overcurrent protection return coefficient and a third-level protection action time are set, and an overcurrent protection configuration parameter is obtained; Performing timing coordination calculation on the differential protection configuration parameters, the impedance protection configuration parameters and the overcurrent protection configuration parameters to obtain a timing coordination relationship of the three-level protection; Input the timing coordination relationship of the three-level protection into the protection logic matrix, and obtain the locking conditions and acceleration action conditions of each level of protection through AND gate and OR gate logic combination operations; A protection start logic criterion is established according to the locking condition and the acceleration action condition to obtain a three-level protection configuration system.

5. The grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment according to claim 1 is characterized in that: The three-level protection configuration system is input into a digital signal processor for real-time monitoring to obtain the action instructions and fault information of the hierarchical protection, including: The parameter matrix of the three-level protection configuration system is loaded into the FLASH memory of the digital signal processor, and the metal shell current and the internal conductor current are sampled to obtain a sampling data sequence; Based on the sampled data sequence, the current difference of the differential protection, the impedance value of the impedance protection and the total current value of the overcurrent protection are calculated respectively, and compared with the setting values ​​of each level of protection to obtain a trigger signal of the protection criterion; The trigger signal of the protection criterion starts the timer counting, and the timing is controlled by the timing interrupt service program to obtain the action instruction of the hierarchical protection; The action instruction of the hierarchical protection is output through the GPIO interface of the DSP to generate a 32-bit status word including the fault occurrence time, fault duration, fault phase, action protection type and protection action time to obtain fault information.

6. The grounding protection method for high-voltage fully enclosed vacuum environmentally friendly GIS equipment according to claim 5 is characterized in that: The grounding protection method of the high-voltage fully enclosed vacuum environmentally friendly GIS equipment also includes: The fault information is subjected to CRC check and data frame encapsulation, and is sent to the host computer monitoring system through the UART interface according to the RS485 communication protocol to obtain real-time monitoring results; Perform sliding window statistics on the protection action times, action times and refusal times of the hierarchical protection action instructions and fault information records in the real-time monitoring results to obtain a two-dimensional feature vector; A fuzzy rule base is established based on the two-dimensional feature vector, and the domain of the action frequency and reliability input variables in the fuzzy rule base is divided into seven fuzzy subsets, and a trapezoidal membership function is calculated for each fuzzy subset to obtain a fuzzy relationship matrix; Performing Mamdani fuzzy reasoning operation based on the fuzzy relationship matrix to obtain specific adjustment values ​​of protection parameters; Based on the specific adjustment values ​​of the protection parameters, the real-time data collected by the SF6 gas pressure sensor, vacuum sensor and temperature and humidity sensor are respectively calculated for deviation from their standard values ​​to obtain the equipment health index, which is then processed in sections to generate an adaptive optimization result.

7. A grounding protection device for high-voltage fully enclosed vacuum environmentally friendly GIS equipment, characterized in that: Steps for implementing the grounding protection method of high-voltage fully enclosed vacuum environmentally friendly GIS equipment as described in any one of claims 1 to 6, wherein the grounding protection device of the high-voltage fully enclosed vacuum environmentally friendly GIS equipment comprises: A decoupling analysis unit is used to perform zero-sequence component and negative-sequence component decoupling analysis on the metal shell current and internal conductor current of the GIS equipment to obtain a zero-sequence equivalent circuit model and a negative-sequence equivalent circuit model; A compensation operation unit, used for performing SF6 gas pressure compensation and vacuum degree compensation operations based on the zero-sequence equivalent circuit model and the negative-sequence equivalent circuit model to obtain a compensated zero-sequence current value and a compensated negative-sequence current value; A calculation unit, used to calculate the amplitude ratio and phase angle difference between the metal shell current and the internal conductor current according to the compensated zero-sequence current value and the compensated negative-sequence current value, obtain a fault criterion threshold, and establish a three-level protection configuration system of differential protection, impedance protection and overcurrent protection; The real-time monitoring unit is used to input the three-level protection configuration system into a digital signal processor to perform real-time monitoring and obtain action instructions and fault information of the hierarchical protection.

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