A direct current circuit breaker control method, device and system

Abstract

This invention relates to the field of DC power distribution protection, and discloses a DC circuit breaker control method, device, and system, comprising: acquiring electrical parameters of a target branch during its operation, wherein a branch DC circuit breaker for controlling the on / off state of the target branch is installed in the target branch; identifying the operating state and confidence level of the target branch based on the electrical parameters; determining electrical protection conditions for the target branch based on the operating state and the confidence level in response to the confidence level being greater than a first threshold; and controlling the operation of the DC circuit breaker based on the comparison result between the electrical parameters and the electrical protection conditions. This invention dynamically determines electrical protection conditions by real-time identification of the operating state and confidence level, avoiding misjudgment of inrush current under a single fixed threshold, achieving adaptive optimization of protection parameters, and enhancing the fault tolerance and reliability of the system.

Description

Technical Field

[0001] This invention relates to the technical field of DC power distribution protection, and specifically to a DC circuit breaker control method, device, and system. Background Technology

[0002] In DC power distribution systems, DC circuit breakers typically perform functions such as isolating branch short-circuit faults, protecting against abnormal loads, and ensuring system operational safety. With the increasing complexity of DC power distribution system applications, the diversification of load types, and the variety of system operating modes, higher demands are being placed on the protection performance of DC circuit breakers.

[0003] DC circuit breaker protection schemes often employ fixed-time-current protection characteristics, fixed-threshold protection methods, or preset energy limit methods for action determination. These schemes trigger the DC circuit breaker to operate when the detected current exceeds the threshold or the energy reaches the limit, by pre-setting fixed protection parameters.

[0004] In related technologies, under complex loads and multiple operating modes, existing fixed protection parameter methods are difficult to accurately distinguish between normal transient processes and real faults. During normal transient processes such as capacitive load charging, motor starting, and converter commissioning, the branch current will experience a large surge in a short period of time. Moreover, some transient processes overlap with real short-circuit faults in terms of amplitude and duration. Relying solely on fixed current thresholds or fixed characteristics for action judgment can easily misjudge normal transients as faults, leading to maloperation or unreliable protection. Summary of the Invention

[0005] This invention provides a DC circuit breaker control method, device, and system to solve the problem that relying solely on fixed current thresholds or fixed characteristics for action determination can easily lead to misjudging normal transients as faults, resulting in malfunctions or unreliable protection.

[0006] In a first aspect, the present invention provides a DC circuit breaker control method, wherein during the operation of a target branch, electrical parameters of the target branch are acquired, and a DC circuit breaker for controlling the on / off state of the target branch is provided in the target branch. The operating status and confidence level of the target branch are identified based on the electrical parameters. In response to the recognition confidence level being greater than a first threshold, the electrical protection conditions of the target branch are determined based on the operating state and the recognition confidence level; The operation of the DC circuit breaker is controlled based on the comparison results between the electrical parameters and the electrical protection conditions.

[0007] This application uses electrical parameters obtained during the operation of the target branch to dynamically determine the electrical protection conditions by identifying the operating status and confidence level of the target branch in real time. This reduces the misjudgment of inrush current under a single fixed threshold, and can more effectively distinguish between normal transient processes and real fault processes, thereby reducing the probability of false operation and improving the protection reliability for the target branch.

[0008] In one optional implementation, the electrical protection conditions of the target branch are determined based on the operating status and identification confidence level, including: Based on a preset mapping relationship, the operating state and the target protection parameters corresponding to the confidence level are determined. The protection parameters include at least two of the following: action current threshold, action delay parameter, and energy limit parameter. The target protection parameters are preprocessed to obtain the electrical protection conditions of the target branch.

[0009] This application generates multi-dimensional protection parameters through a clear mapping relationship and performs preprocessing, making protection actions more precise and improving the accuracy of fault identification.

[0010] In one optional implementation, the operating state and the target protection parameters corresponding to the identification confidence level are determined based on a preset mapping relationship, including: Obtain the bus voltage signal of the DC bus corresponding to the target branch, wherein the DC bus includes several branches; The DC system operating mode is determined based on the bus voltage signal; Based on the DC system operating mode, the preset mapping relationship is queried to obtain the reference protection parameters; Based on the operating status and identification confidence level, the baseline protection parameters are adjusted to obtain the target protection parameters.

[0011] This application determines the DC system operating mode by using the voltage signal of the DC bus, obtains the corresponding reference protection parameters by using the DC system operating mode and the preset mapping relationship, and matches different reference parameter sets by using different DC system operating modes to improve the system's adaptability to changes in operating mode.

[0012] In one optional implementation, the baseline protection parameters are adjusted based on the operating status and identification confidence level to obtain the target protection parameters, including: The identification confidence is adjusted based on a preset baseline confidence level and a preset confidence adjustment coefficient; The target protection parameters are obtained by adjusting the baseline protection parameters based on the adjusted recognition confidence level and the preset state correction coefficient.

[0013] This application constructs a dynamic mapping relationship between operating status and protection parameters. First, the identification confidence is adjusted using a baseline confidence level and a confidence level adjustment coefficient. Then, the baseline protection parameters are adjusted using the adjusted identification confidence level and a status correction coefficient, thereby obtaining target protection parameters that better match the actual situation.

[0014] In one optional implementation, identifying the operating status and confidence level of the target branch based on electrical parameters includes: The timing characteristics of the target branch are determined based on the electrical parameters, and the timing characteristics include at least two of the following: current change rate, voltage change, energy accumulation, and high-frequency component indicators. The operating status of the target branch and the identification confidence level are determined based on the time-series characteristics.

[0015] This application discloses specific parameters of timing features and uses multi-dimensional timing features to determine the operating status and identification confidence of the target branch, reducing the possibility of misjudgment caused by the similarity between branch current transients and short-circuit faults, and improving the accuracy of status identification.

[0016] In one optional implementation, the electrical parameters include the branch current signal and the bus voltage signal of the DC bus corresponding to the target branch. Calculating the timing characteristics of the target branch based on the electrical parameters includes: The rate of change of current is obtained by the difference between the branch current signals based on a preset time interval; The voltage change is obtained by the difference between the bus voltage signals based on a preset time interval; The energy accumulation is obtained based on a preset time interval and the branch current signal; The timing signal of the target branch is obtained based on a preset time interval and the branch current signal; The high-frequency component index is obtained based on the timing signal and the preset cutoff frequency.

[0017] This application clarifies the specific calculation process of time-series features to facilitate the accurate calculation of subsequent operating state categories and identification confidence levels.

[0018] In one optional implementation, determining the operating state of the target branch and the identification confidence level based on the time-series characteristics includes: In response to the current change rate being greater than a first current change rate threshold and the voltage change being greater than a first voltage change threshold, the operating state of the target branch is set to a fault state. In response to the energy accumulation being greater than a preset critical energy accumulation, the duration of the energy accumulation being greater than the critical energy accumulation being within a first time threshold, and the high-frequency component index being less than a preset critical high-frequency component index threshold, the operating state of the target branch is set to a controlled start-up candidate state. In response to the current change rate being greater than a second current change rate threshold, the duration of the current change rate being greater than the second current change rate threshold being less than a second time threshold, and the voltage change being less than a second voltage change threshold, the operating state of the target branch is set to a transient impact candidate state. The weighted deviation of a single feature is calculated based on the aforementioned time-series characteristics, preset typical characteristics, and preset tolerances; The total time-series feature deviation is obtained by summing the weighted deviations of the single features. The confidence level of the time series features is obtained by inverting the total deviation of the time series features and mapping it using an exponential function.

[0019] This application improves the system's reliability and quantitative identification capabilities by setting priorities and confirmation mechanisms for operational status, enabling fault states to be responded to first, and obtaining confidence levels through exponential function mapping.

[0020] In one optional implementation, in response to the identification confidence level being less than a preset conservative threshold, a preset fixed protection curve is obtained and a first historical protection parameter is generated based on the fixed protection curve. The first historical protection parameter includes at least an operating current threshold, an operating delay parameter, and an energy limit parameter. Set the protection parameters from the previous cycle to the second historical protection parameters; Count the number of times the first historical protection parameter is less than the second historical protection parameter; If at least two first historical protection parameters are less than the second historical protection parameter, then the first historical protection parameter is set to a conservative protection strategy. If at least two sub-parameters of the second historical protection parameter are less than the sub-parameters corresponding to the first historical protection parameter, then the second historical protection parameter is set to a conservative protection strategy.

[0021] This application automatically selects the more conservative set of protection parameters from the fixed protection curve and the protection parameters from the previous cycle as the conservative protection strategy by comparing their stringency. This ensures that the conservative protection strategy is always executed when the identification confidence level is less than the conservative threshold, thereby improving the protection reliability of the target branch.

[0022] In a second aspect, the present invention provides a DC circuit breaker control device, comprising: an electrical parameter acquisition module, used to acquire electrical parameters of the target branch during operation of the target branch, wherein the target branch is provided with a DC circuit breaker for controlling the on / off state of the target branch; A branch status identification module is used to identify the operating status and confidence level of the target branch based on the electrical parameters. A protection condition determination module is used to determine the electrical protection conditions of the target branch based on the operating state and the identification confidence level in response to the identification confidence level being greater than a first threshold. The DC circuit breaker operation control module is used to control the operation of the DC circuit breaker based on the comparison results between the electrical parameters and the electrical protection conditions.

[0023] Thirdly, the present invention provides a DC circuit breaker control system, comprising: a DC bus; Multiple branches are connected to the DC bus, and each branch is equipped with a DC circuit breaker and a controller. A signal acquisition unit is connected to the branch circuit and is used to acquire the electrical parameters of the branch circuit. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an application scenario according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating a DC circuit breaker control method according to an embodiment of the present invention; Figure 3 This is a structural block diagram of a DC circuit breaker control system according to an embodiment of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0029] As an optional application scenario of this invention, such as Figure 1 As shown, this application supplies power to the DC bus via a DC power supply or an energy storage system. An upstream DC circuit breaker is installed on the DC bus. The DC bus contains several branches. In this embodiment, it contains four branches. Each branch is equipped with a DC circuit breaker. The four branches are connected to different loads. In this application, capacitive loads, motor loads, resistive loads, and energy storage loads are connected to the DC bus.

[0030] According to an embodiment of the present invention, a DC circuit breaker control method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0031] This embodiment provides a DC circuit breaker control method. Figure 2 This is a flowchart of a DC circuit breaker control method according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: Step S201: During the operation of the target branch, the electrical parameters of the target branch are acquired. The target branch is equipped with a DC circuit breaker for controlling the on / off state of the target branch.

[0032] The electrical parameters specifically include at least branch current signals and bus voltage signals, or current and voltage amplitudes after preliminary filtering. It should be understood that although this embodiment and subsequent embodiments primarily use current and voltage as typical parameters, in other embodiments, electrical parameters can also encompass physical quantities that characterize the electrical state, such as power, impedance, and frequency, as long as they can provide data support for subsequent state identification. Each branch is equipped with an independent branch DC circuit breaker, enabling independent closed-loop protection control logic for each branch and reducing the risk of multi-branch coupling interference.

[0033] Step S202: Identify the operating status and confidence level of the target branch based on electrical parameters.

[0034] Operating status is a qualitative classification of the current operating condition of a branch, which may include normal steady state, fault state, controlled start-up state, transient impact state, etc. Identification confidence is a quantitative indicator characterizing the reliability of the identification result. Considering that transient processes and fault processes in DC systems overlap in amplitude and duration, single feature discrimination often has uncertainty. When the confidence is high, it indicates that the currently identified operating status highly matches the actual operating condition, and the system can confidently adopt the corresponding strategy; when the confidence is low, it indicates that the identification result may be in a fuzzy boundary.

[0035] Step S203: In response to the identification confidence level being greater than the first threshold, the electrical protection conditions of the target branch are determined based on the operating status and the identification confidence level.

[0036] The electrical protection conditions can be expressed as at least one or a combination of operating current threshold, operating delay parameter, and energy limit parameter, or they can be a protection curve or piecewise function containing the above parameters. Through the dual drive of operating status and confidence level, the electrical protection conditions achieve adaptive and fine adjustment.

[0037] For example, when a controlled start is identified with a high confidence level, the protection conditions are appropriately relaxed to allow the start-up impact to pass; when a fault is identified with a high confidence level, the protection conditions are rapidly tightened to accelerate isolation.

[0038] Step S204: Based on the comparison results of electrical parameters and electrical protection conditions, control the operation of the DC circuit breaker.

[0039] The actions of controlling a DC circuit breaker are not limited to triggering tripping; they can also include issuing warning signals, initiating reclosing logic, or sending interlocking signals to adjacent branches. While controlling a DC circuit breaker involves tripping it to isolate a fault, under certain special operating conditions, the control action can also be to maintain the closed state to withstand controllable impacts, as long as the action is based on comparison results and conforms to the intent of the current dynamic protection conditions.

[0040] The DC circuit breaker control method provided in this embodiment can more effectively distinguish between normal transient processes and real fault processes by jointly extracting current, voltage and frequency domain characteristics and identifying the operating status in real time, thereby reducing the probability of malfunction.

[0041] This embodiment, based on step S202 of embodiment 1, elaborates on the specific algorithm branches for temporal feature extraction and state recognition, specifically including: Step S301: Calculate the timing characteristics of the target branch based on electrical parameters. The timing characteristics include at least two of the following: current change rate, voltage change, energy accumulation, and high-frequency component indicators.

[0042] Among them, the current change rate, voltage change, energy accumulation and high-frequency component index included in the time series characteristics describe the transient process from four independent dimensions: change rate, system support strength, impact accumulation effect and waveform distortion degree. This allows the operating conditions that originally overlapped on the amplitude axis to be clearly separated in the multi-dimensional feature space.

[0043] It should be understood that although this embodiment lists these four specific features, in other embodiments, timing features may also include voltage change rate, current integral value, power change amount, etc., as long as they can characterize the abrupt change characteristics of the branch operation process from different physical dimensions.

[0044] Specifically, the electrical parameters include the branch current signal and the bus voltage signal of the DC bus corresponding to the target branch. The above step S301 includes: Step S3011: Obtain the rate of change of current based on the difference between the branch current signals at a preset time interval.

[0045] Specifically, the formula is as follows: ; in, for The branch current signal at the sampling point, for The branch current signal at the sampling point, The sampling interval is used to accurately capture the extremely fast rising edge at the initial stage of a fault, while some normal transients, such as motor startup, have relatively flat rising edges despite large amplitudes, thus enabling preliminary differentiation in terms of rate of change. The branch current signal and bus voltage signal of the branch are collected simultaneously, and the collected data are cached and updated based on a sliding time window.

[0046] Step S3012: The voltage change is obtained based on the difference between the bus voltage signals at preset time intervals.

[0047] The voltage change represents the degree of voltage drop at the bus, and its calculation is as follows: ; in, The voltage at the current moment. The voltage at the start of the preset time interval is the actual short-circuit fault. The bus voltage often drops significantly due to the presence of internal resistance in the system, while controlled start-up or transient impact usually does not cause a serious voltage drop.

[0048] Step S3013: The energy accumulation is obtained based on the preset time interval and the branch current signal.

[0049] The energy accumulation represents the cumulative effect of impact intensity per unit time, as shown in the following formula: ; in, The amount of energy accumulated. for The current value at a given time, or in some implementations where power characteristics need to be considered, can also be expressed using the following formula: ; in, The amount of energy accumulated. for The current value at time [time]. for The voltage value at a given moment.

[0050] It is worth mentioning that the energy accumulation compensates for the deficiency that instantaneous characteristics cannot reflect the duration of the impact. For example, although the rate of change is not large in the early stage of motor startup, the long duration leads to a significant excess of energy accumulation, thereby separating the controlled startup from the brief transient impact.

[0051] Step S3014: Obtain the timing signal of the target branch based on the preset time interval and the branch current signal.

[0052] Step S3015: Obtain high-frequency component indices based on timing signals and preset cutoff frequencies.

[0053] The high-frequency component index characterizes the proportion of high-frequency disturbance components in the current waveform, and the formula is as follows: ; in, The target frequency band components are extracted using methods such as Fast Fourier Transform, bandpass filtering, or high-pass filtering. The total signal spectrum is represented by the fact that real faults are often accompanied by electric arcs or the introduction of nonlinear components, generating a large number of high-frequency harmonics. In contrast, the current waveform of the controlled process during normal operation is relatively smooth, with a very low proportion of high frequencies.

[0054] Step S302: Determine the operating status of the target branch and identify the confidence level based on the time sequence characteristics.

[0055] Specifically, step S302 includes: Step S3021: In response to the current change rate being greater than a first current change rate threshold and the voltage change being greater than a first voltage change threshold, the operating state of the target branch is set to a fault state.

[0056] Among them, the fault state is usually accompanied by a rapid rise in current and a significant drop in bus voltage, which causes the system to become drastically unbalanced due to low impedance short circuit. When the rate of change of current is greater than the first current rate of change threshold (e.g., 800A / ms) and the amount of voltage change is greater than the first voltage change threshold (e.g., a 15% drop in rated voltage), the system is judged to be in a fault state.

[0057] Step S3022: In response to the energy accumulation being greater than a preset critical energy accumulation, the duration of the energy accumulation being greater than the critical energy accumulation being within a first time threshold, and the high-frequency component index being less than a preset critical high-frequency component index threshold, the operating state of the target branch is set to a controlled start candidate state.

[0058] Controlled start-up is usually accompanied by large energy accumulation but smooth waveform, that is, the large current is continuous but controlled when the load such as motor starts. When the energy accumulation is greater than the critical energy accumulation and the duration is within the first time threshold (indicating that the impact is not instantaneous), and the high-frequency component index is less than the critical high-frequency component index threshold (indicating that the waveform is smooth and there is no electric arc), the system determines that it is a controlled start-up state.

[0059] Step S3023: In response to the current change rate being greater than the second current change rate threshold, the duration of the current change rate being greater than the second current change rate threshold being less than the second time threshold, and the voltage change being less than the second voltage change threshold, the operating state of the target branch is set to transient impact state.

[0060] Among them, the core criterion for transient impact is that the current changes instantaneously but recovers quickly and the voltage does not drop, reflecting instantaneous processes such as capacitor charging; when the rate of change of current is greater than the second rate of change of current threshold but the duration is extremely short (less than the second time threshold), and the voltage change is less than the second rate of change of voltage threshold (the voltage is basically maintained), the system determines it to be a candidate state of transient impact.

[0061] It is worth mentioning that when multiple candidate states are satisfied simultaneously within the same cycle, the system strictly follows the priority logic of fault states taking precedence over controlled start states, and controlled start states taking precedence over transient impact states when outputting the judgment result. In DC systems, the cost of missing a real fault is far higher than the cost of misjudging a normal transient state, and fault states must be responded to first to ensure equipment safety.

[0062] Step S3024: Calculate the single-feature weighted deviation based on time-series features, preset typical features, and preset tolerances.

[0063] Let the current feature vector be... Target state The typical feature center is The tolerance range for each feature is: The weighted bias formula for a single feature is as follows: ; in, For the current feature vector The first one taken from Real-time calculation results of each feature To start from the target state Typical feature center The first one taken from Standard values ​​of each feature To start from the target state tolerance range vector The first one taken from The maximum allowable deviation value for each feature.

[0064] Step S3025: Accumulate the weighted bias of single features to obtain the total bias of time series features.

[0065] Wherein, the weighting coefficient is And satisfy The formula for the total deviation of time series characteristics is as follows: ; in, For the first The weight coefficients of each feature For the current feature vector The first one taken from Real-time calculation results of each feature To start from the target state Typical feature center The first one taken from The standard value of each feature, To start from the target state tolerance range vector The first one taken from The maximum allowable deviation value for each feature.

[0066] Step S3026: Invert the total deviation of the time series features and obtain the confidence level of the time series features through exponential function mapping.

[0067] The formula for confidence level is as follows: ; in, For the first The confidence level of the target state. For the mapping of exponential functions, For the first The weight coefficients of each feature For the current feature vector The first one taken from Real-time calculation results of each feature To start from the target state Typical feature center The first one taken from The standard value of each feature, To start from the target state tolerance range vector The first one taken from The maximum allowable deviation value for each feature.

[0068] This embodiment employs an exponential mapping formula. The exponential function has the characteristic of continuous monotonically decreasing. When the total characteristic deviation fluctuates slightly within the critical range, the confidence level can smoothly transition rather than discretely jumping between 0 and 1. This continuous quantification evaluation mechanism reduces the drastic fluctuations in protection parameters caused by discrete jumps in confidence level, providing a stable driving factor for the smooth dynamic adjustment of subsequent protection parameters. The exponential function has the characteristic of rapid decay when the deviation increases, ensuring that the system can quickly revert to a conservative strategy under low confidence conditions. Thus, while retaining adaptive sensitivity, it significantly improves the robustness and safety of the protection system.

[0069] It is worth mentioning that this application can also use the trained classification model to obtain the confidence score; the model input is the feature vector (4-6 dimensions) extracted within the sliding time window, and the output is the probability value of each state category. The category corresponding to the highest probability is taken as the running state category, and the highest probability value is taken as the recognition confidence score.

[0070] The classification model can be a support vector machine, random forest, shallow neural network, or other lightweight model suitable for embedded deployment. When training the classification model offline, it is recommended to collect at least 5000 sets of normal transient, controlled start, and artificially induced short-circuit fault data as the training set, and use cross-validation methods for training.

[0071] Based on step S203, this embodiment elaborates on the mapping and adjustment branches of the dynamic generation of protection parameters.

[0072] Step S401: Based on the preset mapping relationship, determine the operating status and identify the target protection parameters corresponding to the confidence level. The protection parameters include at least two of the following: action current threshold, action delay parameter, and energy limit parameter.

[0073] Among them, the operating current threshold determines the minimum current threshold for the DC circuit breaker to detect faults, the operating delay parameter determines the tolerance time of the DC circuit breaker to withstand impacts, and the energy limit parameter constrains the limit of short-term impacts from the perspective of thermal accumulation.

[0074] It is worth noting that not all time-series features must be calculated simultaneously in all operational state determinations. This application emphasizes selecting at least two features for joint discrimination, not that all four features must be involved. Different operational states can be obtained using different feature combinations, for example: 1) Fault status can be identified primarily based on the rate of change of current + the amount of change of voltage, because DC short circuits are usually characterized by a rapid rise in current and a significant drop in bus voltage. 2) Controlled start-up status can be identified primarily based on the current change rate + duration + energy accumulation, because it usually has a high impact but the continuous process is controlled and the bus voltage drop is limited. 3) Transient impact states can be identified primarily based on the current change rate + duration + high-frequency component indicators, because such states are usually short in duration, recover quickly, and may be accompanied by significant high-frequency disturbances.

[0075] Therefore, this application does not require all four types of features to be calculated. Instead, it dynamically selects two, three, or four features for state discrimination based on hardware computing power, sampling conditions, and target state category. In order to ensure protection reliability, in scenarios with limited computing power, it is preferable to retain at least the current change rate and voltage change amount. When it is necessary to improve the ability to distinguish between transient and fault states, energy accumulation and / or high-frequency component indicators are introduced.

[0076] Step S402: Preprocess the target protection parameters to obtain the electrical protection conditions of the target branch.

[0077] The preprocessing process includes rate-of-change constraints and historical smoothing correction. Rate-of-change constraints limit the variation range of each protection parameter within adjacent update cycles, ensuring a smooth and controllable parameter evolution trajectory. Historical smoothing correction uses the effective parameters from the previous cycle to weight and filter the new parameters for the current cycle, removing parameter jitter caused by signal sampling noise or transient interference. Through preprocessing, the electrical protection conditions are no longer fragile instantaneous calculated values, but robust boundaries refined through historical accumulation and constraints. This significantly improves the robustness and engineering reliability of the protection system while retaining adaptive sensitivity.

[0078] Specifically, the rate of change constraints include: The changes in the action current threshold, action delay parameter, and energy limit parameter within two adjacent parameter update cycles shall not exceed the corresponding preset change limits.

[0079] Specifically, to prevent the protection parameters from fluctuating drastically with short-term characteristic changes, the system applies a rate-of-change constraint to the new parameters generated in each cycle, as shown in the following formula: ; ; ; in, The new current protection action threshold is calculated in real time within the k-th cycle based on the current power grid operating conditions and fault detection results. This represents the current threshold for actual operation of the protection device within the (k-1)th cycle after constraints and smoothing. This represents the maximum permissible change in the operating current threshold during a single operation. The action protection delay is calculated in real time within the k-th cycle. The actual action protection delay parameters used in the (k-1)th cycle. This represents the maximum permissible change in the action delay parameter per cycle. The new energy protection action threshold is calculated in real time during the k-th cycle. The threshold value for energy protection action actually used in the (k-1)th cycle. This represents the maximum permissible variation of the energy limit parameter in a single instance.

[0080] Then, perform exponential smoothing correction on the constrained parameters: ; in, This represents the protection parameter after smooth correction within the k-th period. This indicates the protection parameters generated based on the status identification results in this cycle. The smoothing coefficient is between 0 and 1. In this embodiment... Preferably, it is 0.2 to 0.6. This represents the protection parameter after smooth correction within the (k-1)th period.

[0081] Step S403: Obtain the bus voltage signal of the DC bus corresponding to the target branch. The DC bus includes several branches.

[0082] The bus voltage signal can be obtained through direct sampling or received from the upper-level energy management system via the communication bus.

[0083] Step S404: Determine the DC system operating mode based on the bus voltage signal.

[0084] In DC power distribution systems, the operating modes include at least grid-connected mode and islanded mode. In grid-connected mode, the AC grid provides strong short-circuit capacity support, the bus voltage is relatively rigid, and the fault current evolves rapidly and has a very large amplitude. In islanded mode, the system relies solely on local power supply, the short-circuit capacity is greatly reduced, the bus voltage is less rigid, and the fault current may not reach the traditional fixed threshold.

[0085] Specifically, the system operating mode can be obtained through any of the following methods: (1) receiving communication signals sent by the host computer or energy management system; (2) making local judgments based on the bus voltage amplitude, fluctuation rate, and whether there are AC side grid connection characteristics; (3) monitoring the status of the contactor / DC circuit breaker at the interface between the DC bus and the AC grid. Different operating modes correspond to different sets of reference protection parameters, and the operating status category is used for dynamic adjustment based on the set of reference protection parameters.

[0086] Step S405: Based on the system operating mode, query the preset mapping relationship to obtain the baseline protection parameters.

[0087] For example, in grid-connected mode, due to the large short-circuit current, the reference operating current threshold can be set higher to avoid normal transient impacts, and the reference operating delay can be relatively lenient. However, in islanded mode, due to the small short-circuit current, maintaining the high reference current threshold of grid-connected mode could easily lead to a fatal danger of the fault current not reaching the threshold and failing to operate. Therefore, in islanded mode, the reference operating current value must be significantly reduced, and the reference operating delay value must be shortened to improve fault operating sensitivity. This mechanism of dynamically adjusting reference parameters with mode switching fundamentally solves the problem of protection failure during mode switching using traditional fixed parameters.

[0088] Step S406: Based on the operating status and identification confidence level, adjust the baseline protection parameters to obtain the target protection parameters.

[0089] Specifically, the parameter mapping relationship can be implemented using a lookup table, a piecewise function, or an analytical function. The parameter mapping relationship takes the operating state category, identification confidence level, and system operating mode as inputs, and the operating current threshold as input. Action delay parameters and energy limit parameters As output.

[0090] Let the current operating mode of the system be M, the operating state category be S, and the recognition confidence level be C, where 0 ≤ C ≤ 1, then the action current threshold is: ; Action delay parameters: ; Energy limit parameters: ; in, These are the baseline parameters for different operating modes; This is the state correction coefficient; The baseline confidence level can be set to 0.5. This is the confidence level adjustment coefficient.

[0091] For example, the fault state can be set as follows: ; Controlled startup state: ; Transient impact state: .

[0092] Through the above mapping, the protection parameters tend to be more sensitive under fault conditions, the protection parameters are moderately relaxed under controlled start-up conditions, and short-term impacts are allowed to pass under transient impact conditions, but energy constraints are still retained.

[0093] Based on step S300, this embodiment elaborates on the fallback logic branch of the conservative protection strategy.

[0094] Step 501: In response to the identification confidence level being less than a preset conservative threshold, a preset fixed protection curve is obtained and a first historical protection parameter is generated based on the fixed protection curve. The first historical protection parameter includes at least an operating current threshold, an operating delay parameter, and an energy limit parameter.

[0095] The conservative threshold is the lower limit for triggering the system to enter the safety backoff mode. It should be understood that the specific value of the conservative threshold is not fixed and can be adjusted according to the system's stringent safety requirements. For example, in high-voltage DC systems prone to fatal failures, the conservative threshold can be set higher, such as 0.7, while in low-voltage systems with frequent but limited transient impacts, the conservative threshold can be appropriately lowered, such as 0.5. This embodiment strictly limits the conservative threshold to be lower than the recovery threshold. If the conservative threshold is the same as or too close to the recovery threshold, when the identification confidence repeatedly crosses the critical range due to signal noise or transient fluctuations, the system will frequently switch between adaptive protection mode and conservative protection mode, causing severe oscillations in protection parameters or even malfunctions. By setting a conservative threshold lower than the recovery threshold, a confidence hysteresis range is formed. Backoff only occurs when the confidence drops to a lower conservative threshold, and it must wait until the confidence fully recovers to a higher recovery threshold before exiting backoff. This asymmetric threshold design fundamentally eliminates the uncertainty caused by critical jitter.

[0096] The fixed protection curve is a static protection benchmark preset by the system at the factory or manually adjusted. It does not change with real-time operating conditions and represents an absolute safety baseline verified by long-term engineering. The first historical protection parameters are the specific action thresholds analyzed based on the fixed curve at the current moment, which include at least three core sub-parameters: action current threshold, action delay parameter, and energy limit parameter.

[0097] Step 502: Set the protection parameters of the previous cycle to the second historical protection parameters.

[0098] Among them, the second historical protection parameter is the protection threshold that the system actually took effect in the previous update cycle. The parameter of the previous cycle is the security boundary that the system has most recently confirmed. If the current cycle cannot generate new reliable parameters due to insufficient confidence, then using the most recent reliable boundary is often smoother in engineering than directly jumping to the factory fixed curve.

[0099] It should be understood that although this embodiment uses the previous period parameter as the second historical parameter, in other embodiments, a weighted smoothing parameter of the past several periods can also be used as the second historical parameter, as long as it represents the effective safety benchmark recently confirmed by the system.

[0100] Step S503: Count the number of times the first historical protection parameter is less than the second historical protection parameter.

[0101] Step S504: If at least two first historical protection parameters are less than the second historical protection parameter, then the first historical protection parameter is set to a conservative protection strategy.

[0102] Step S505: If at least two sub-parameters of the second historical protection parameter are less than the sub-parameters corresponding to the first historical protection parameter, then the second historical protection parameter is set to a conservative protection strategy.

[0103] In this system, the more stringent set of candidate parameters is automatically selected as the final conservative protection strategy. A specific numerical example illustrates this: Assume a system with a rated current of 200A. The first historical protection parameters, generated based on a fixed protection curve, are: operating current threshold 90A, operating delay parameter 1.5ms, and energy limit parameter 8500A²ms. The second historical protection parameters, effective in the previous cycle, are: operating current threshold 95A, operating delay parameter 1.2ms, and energy limit parameter 9000A²ms. The system first compares each parameter: In terms of operating current threshold, 90A is less than 95A, making the first historical parameter more stringent; in terms of operating delay parameter, 1.5ms is greater than 1.2ms, making the second historical parameter more stringent; in terms of energy limit parameter, 8500A²ms is less than 9000A²ms, making the first historical parameter more stringent. The statistical results show that two parameters (current and energy) in the first historical protection parameter are less than those in the second historical protection parameter, satisfying at least two conditions. Therefore, the system sets the first historical protection parameter as the conservative protection strategy.

[0104] It is worth noting that the final selection in this embodiment is not a mechanical copy of the original values ​​of the first historical protection parameters, but rather a step-by-step reorganization based on the principle of strictness optimization: the final effective conservative protection strategy is an operating current threshold of 90A (taking the stricter value from the first history), an operating delay parameter of 1.2ms (taking the stricter value from the second history), and an energy limit parameter of 8500A²ms (taking the stricter value from the first history). This step-by-step comparison and reorganization mechanism ensures that the final strategy does not relax the protection boundaries in any dimension. If all three items must be stricter before selecting this set, then if only one item is slightly more lenient (e.g., the difference between a delay of 1.5ms and 1.2ms is minimal), the system may be forced to select another set of parameters that are significantly more lenient in two key dimensions, resulting in a significant regression in overall safety.

[0105] It is worth mentioning that an independent processing unit is configured between the branch DC circuit breaker and the load. The independent processing unit includes at least a feature buffer for storing timing characteristics, a status register for storing operating status, and a parameter register for storing protection parameters; and a preset selection time interval is set between adjacent branch DC circuit breakers.

[0106] Specifically, in a multi-branch DC distribution system, each branch maintains its own independent feature buffer, status identification results, and protection parameter register, and independently executes the aforementioned adaptive protection setting process. To ensure coordination between upper and lower level protection, a selective time interval is preset between adjacent protection units. For lower-level branches, the action delay is no greater than the action delay of the corresponding upper-level branch minus... This prioritizes the disconnection of faulty branches, thereby reducing the scope of the fault's impact. In this embodiment, The optimal timeframe is 0.2ms to 1ms. Independent identification of multiple branches and parameter coordination can improve the accuracy of fault location and isolation.

[0107] It is worth mentioning that in a multi-branch DC power distribution system, each branch is equipped with a corresponding DC circuit breaker and maintains independent sampling buffers, feature extraction results, status recognition results, recognition confidence levels, and protection parameter registers.

[0108] To prevent a fault in one branch circuit from causing maloperation of the upstream circuit breaker or other non-faulty branch circuit breakers, this embodiment sets a selective time interval Δt between the upstream and downstream protection units. For any downstream branch circuit breaker, its operating delay parameter t... branch It should meet the following requirements: ; Among them, t upper The corresponding action delay parameter of the upper-level protection unit is Δt, which is a selective time interval, preferably 0.2ms to 1ms.

[0109] When a short-circuit fault occurs in a branch, the corresponding status identification result of that branch is prioritized to enter the fault state. Based on the fault state, a lower operating current threshold, shorter operating delay, and lower energy limit are generated, causing the circuit breaker of that branch to perform isolation operation first. If the faulty branch circuit breaker fails to complete isolation within a preset time, and the fault current or bus voltage drop continues to exist, the upstream circuit breaker will perform protection operation according to its backup protection parameters.

[0110] Through the above methods, this embodiment can achieve priority isolation of faulty branches, avoid power outages in fault-free branches, and improve the power supply continuity and fault location accuracy of multi-branch DC power distribution systems.

[0111] This embodiment also provides a DC circuit breaker control device, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0112] This embodiment provides a DC circuit breaker control device, such as... Figure 3 As shown, it includes: The electrical parameter acquisition module 301 is used to acquire the electrical parameters of the target branch during the operation of the target branch. The target branch is equipped with a branch DC circuit breaker for controlling the on and off of the target branch. The branch status identification module 302 is used to identify the operating status of the target branch and the identification confidence level based on electrical parameters; The protection condition determination module 303 is used to determine the electrical protection conditions of the target branch based on the operating status and the identification confidence level in response to the identification confidence level being greater than a first threshold. The DC circuit breaker operation control module 304 is used to control the operation of the DC circuit breaker based on the comparison results of electrical parameters and electrical protection conditions.

[0113] In some optional implementations, the protection condition determination module 303 includes: determining the operating state and identifying the target protection parameters corresponding to the confidence level based on a preset mapping relationship, wherein the protection parameters include at least two of the following: operating current threshold, operating delay parameter and energy limit parameter; and preprocessing the target protection parameters to obtain the electrical protection conditions of the target branch.

[0114] In some alternative implementations, the protection condition determination module 303 includes: The bus voltage signal of the DC bus corresponding to the target branch is obtained, and the DC bus includes several branches; the DC system operation mode is determined based on the bus voltage signal; a preset mapping relationship is queried based on the DC system operation mode to obtain the reference protection parameters; the reference protection parameters are adjusted based on the operation status and the identification confidence level to obtain the target protection parameters.

[0115] In some optional implementations, the protection condition determination module 303 includes: adjusting the identification confidence based on a preset baseline confidence and a preset confidence adjustment coefficient; and adjusting the baseline protection parameters based on the adjusted identification confidence and a preset state correction coefficient to obtain the target protection parameters.

[0116] In some alternative implementations, the DC circuit breaker operation control module 304 includes: The timing characteristics of the target branch are determined based on electrical parameters, including at least two of the following: current change rate, voltage change, energy accumulation, and high-frequency component indicators; the operating status of the target branch and the confidence level are determined based on the timing characteristics.

[0117] In some alternative implementations, the DC circuit breaker operation control module 304 includes: The current change rate is obtained by the difference between the branch current signals based on the preset time interval; the voltage change is obtained by the difference between the bus voltage signals based on the preset time interval; the energy accumulation is obtained based on the preset time interval and the branch current signal; the timing signal of the target branch is obtained based on the preset time interval and the branch current signal; and the high-frequency component index is obtained based on the timing signal and the preset cutoff frequency.

[0118] In some optional implementations, the DC circuit breaker operation control module 304 includes: in response to identifying a confidence level less than a preset conservative threshold, acquiring a preset fixed protection curve and generating a first historical protection parameter based on the fixed protection curve, wherein the first historical protection parameter includes at least an operating current threshold, an operating delay parameter, and an energy limit parameter; setting the protection parameter of the previous cycle as a second historical protection parameter; counting the number of first historical protection parameters less than the second historical protection parameter; if at least two first historical protection parameters are less than the second historical protection parameter, then setting the first historical protection parameter as a conservative protection strategy; if at least two sub-parameters of the second historical protection parameter are less than the sub-parameters corresponding to the first historical protection parameter, then setting the second historical protection parameter as a conservative protection strategy.

[0119] The DC circuit breaker control system provided in this embodiment of the invention can execute the DC circuit breaker control method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0120] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A DC circuit breaker control method, characterized in that, The method includes: During the operation of the target branch, the electrical parameters of the target branch are acquired. The target branch is equipped with a DC circuit breaker for controlling the on / off state of the target branch. Identifying the operating status and confidence level of the target branch based on the electrical parameters specifically includes: The timing characteristics of the target branch are determined based on the electrical parameters, which include the branch current signal and the bus voltage signal of the DC bus corresponding to the target branch. The timing characteristics include at least two of the following: current change rate, voltage change, energy accumulation, and high-frequency component indicators, specifically including: The rate of change of current is obtained by the difference between the branch current signals based on a preset time interval; The voltage change is obtained by the difference between the bus voltage signals based on a preset time interval; The energy accumulation is obtained based on a preset time interval and the branch current signal; The timing signal of the target branch is obtained based on a preset time interval and the branch current signal; The high-frequency component index is obtained based on the timing signal and the preset cutoff frequency; Determining the operating state of the target branch and the identification confidence level based on the timing features specifically includes: in response to the current change rate being greater than a first current change rate threshold and the voltage change being greater than a first voltage change threshold, setting the operating state of the target branch to a fault state; In response to the energy accumulation being greater than a preset critical energy accumulation, the duration of the energy accumulation being greater than the critical energy accumulation being within a first time threshold, and the high-frequency component index being less than a preset critical high-frequency component index threshold, the operating state of the target branch is set to a controlled start-up candidate state. In response to the current change rate being greater than a second current change rate threshold, the duration of the current change rate being greater than the second current change rate threshold being less than a second time threshold, and the voltage change being less than a second voltage change threshold, the operating state of the target branch is set to a transient impact candidate state. The weighted deviation of a single feature is calculated based on the aforementioned time-series characteristics, preset typical characteristics, and preset tolerances; The total time-series feature deviation is obtained by summing the weighted deviations of the single features. The confidence level of the time series features is obtained by inverting the total deviation of the time series features and mapping it using an exponential function. In response to the recognition confidence level being greater than a first threshold, the electrical protection conditions of the target branch are determined based on the operating state and the recognition confidence level; The operation of the DC circuit breaker is controlled based on the comparison results between the electrical parameters and the electrical protection conditions.

2. The method according to claim 1, characterized in that, Based on operational status and identification confidence level, including: Based on a preset mapping relationship, the operating state and the target protection parameters corresponding to the confidence level are determined. The protection parameters include at least two of the following: action current threshold, action delay parameter, and energy limit parameter. The target protection parameters are preprocessed to obtain the electrical protection conditions of the target branch.

3. The method according to claim 2, characterized in that, The process of determining the operating state and identifying the target protection parameters corresponding to the confidence level based on a preset mapping relationship includes: Obtain the bus voltage signal of the DC bus corresponding to the target branch, wherein the DC bus includes several branches; The DC system operating mode is determined based on the bus voltage signal; Based on the DC system operating mode, the preset mapping relationship is queried to obtain the reference protection parameters; Based on the operating status and identification confidence level, the baseline protection parameters are adjusted to obtain the target protection parameters.

4. The method according to claim 3, characterized in that, The target protection parameters are obtained by adjusting the baseline protection parameters based on the operating status and identification confidence level, including: The identification confidence is adjusted based on a preset baseline confidence level and a preset confidence adjustment coefficient; The target protection parameters are obtained by adjusting the baseline protection parameters based on the adjusted recognition confidence level and the preset state correction coefficient.

5. The method according to claim 1, characterized in that, The method further includes: In response to the identification confidence level being less than a preset conservative threshold, a preset fixed protection curve is obtained and a first historical protection parameter is generated based on the fixed protection curve. The first historical protection parameter includes at least an operating current threshold, an operating delay parameter, and an energy limit parameter. Set the protection parameters from the previous cycle to the second historical protection parameters; Count the number of times the first historical protection parameter is less than the second historical protection parameter; If at least two first historical protection parameters are less than the second historical protection parameter, then the first historical protection parameter is set to a conservative protection strategy. If at least two sub-parameters of the second historical protection parameter are less than the sub-parameters corresponding to the first historical protection parameter, then the second historical protection parameter is set to a conservative protection strategy.

6. A DC circuit breaker control device, implementing the method as described in any one of claims 1-5, characterized in that, The device includes: An electrical parameter acquisition module is used to acquire the electrical parameters of the target branch during the operation of the target branch, wherein a DC circuit breaker for controlling the on / off state of the target branch is provided in the target branch; A branch status identification module is used to identify the operating status and confidence level of the target branch based on the electrical parameters. The branch status identification module is specifically used to determine the timing characteristics of the target branch based on the electrical parameters. The electrical parameters include the branch current signal and the bus voltage signal of the DC bus corresponding to the target branch. The timing characteristics include at least two of the following: current change rate, voltage change, energy accumulation, and high-frequency component indicators. The rate of change of current is obtained by the difference between the branch current signals based on a preset time interval; The voltage change is obtained by the difference between the bus voltage signals based on a preset time interval; The energy accumulation is obtained based on a preset time interval and the branch current signal; The timing signal of the target branch is obtained based on a preset time interval and the branch current signal; The high-frequency component index is obtained based on the timing signal and the preset cutoff frequency; Determining the operating state of the target branch and the identification confidence level based on the timing features specifically includes: in response to the current change rate being greater than a first current change rate threshold and the voltage change being greater than a first voltage change threshold, setting the operating state of the target branch to a fault state; In response to the energy accumulation being greater than a preset critical energy accumulation, the duration of the energy accumulation being greater than the critical energy accumulation being within a first time threshold, and the high-frequency component index being less than a preset critical high-frequency component index threshold, the operating state of the target branch is set to a controlled start-up candidate state. In response to the current change rate being greater than a second current change rate threshold, the duration of the current change rate being greater than the second current change rate threshold being less than a second time threshold, and the voltage change being less than a second voltage change threshold, the operating state of the target branch is set to a transient impact candidate state. The weighted deviation of a single feature is calculated based on the aforementioned time-series characteristics, preset typical characteristics, and preset tolerances; The total time-series feature deviation is obtained by summing the weighted deviations of the single features. The confidence level of the time series features is obtained by inverting the total deviation of the time series features and mapping it using an exponential function. A protection condition determination module is used to determine the electrical protection conditions of the target branch based on the operating state and the identification confidence level in response to the identification confidence level being greater than a first threshold. The DC circuit breaker operation control module is used to control the operation of the DC circuit breaker based on the comparison results between the electrical parameters and the electrical protection conditions.

7. A DC circuit breaker control system for executing the DC circuit breaker control method according to any one of claims 1 to 5, characterized in that, The system includes: DC bus; Multiple branches are connected to the DC bus, and each branch is equipped with a DC circuit breaker and a controller. A signal acquisition unit is connected to the branch circuit and is used to acquire the electrical parameters of the branch circuit.

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