Substation dc system capacitor risk threshold analysis method and device and storage medium

Abstract

The substation DC system capacitance risk threshold analysis method, device and storage medium provided by the application can first acquire a simplified calculation model of a relay protection device in a substation DC system and rated current of the relay protection device, breaker opening current, rated voltage and balance bridge resistance of the substation DC system when analyzing the capacitance risk threshold of the substation DC system; then determine the action current when triggering the relay protection device to act; then determine the duration when the actual current flowing through the relay protection device is not less than the action current through the simplified calculation model when a single-point grounding event occurs; and finally calculate the capacitance risk threshold of the substation DC system. The process can efficiently and quickly calculate the capacitance risk threshold of the substation DC system, thereby ensuring the correctness of the relay protection device operation, improving the action accuracy of the relay protection device and ensuring the safety of the power grid.

Description

Technical Field

[0001] This application relates to the field of relay protection technology, and in particular to a method, device and storage medium for analyzing the capacitance risk threshold of a DC system in a substation. Background Technology

[0002] With the rapid development of my country's social economy, the scale of the power system has continued to expand, especially with the continuous application of new technologies, making substation structures increasingly complex. Substation DC systems all have ground capacitance (ranging from a few microfarads to hundreds of microfarads). The higher the voltage level and the larger the scale of the substation, the greater the ground capacitance. The ground capacitance of DC systems varies significantly between different substations, especially since insulation monitoring devices contain ground capacitance, greatly increasing the DC system's ground capacitance. If a single-point grounding event occurs in the input circuit of a relay protection device (TBJ), and the DC system's ground capacitance is also large, it will cause the relay protection device to malfunction.

[0003] As the last line of defense for the safe and stable operation of the power grid, relay protection devices pose a significant threat to grid safety if their operation is flawed. Therefore, it is necessary to design a method for analyzing and calculating the capacitance risk threshold of substation DC systems to improve the accuracy of relay protection device operation and ensure grid safety. Summary of the Invention

[0004] The purpose of this application is to at least address one of the aforementioned technical deficiencies, particularly the lack of a method in the prior art for analyzing and calculating the capacitance risk threshold of a substation DC system, thereby improving the accuracy of relay protection device operation and ensuring power grid safety.

[0005] This application provides a method for analyzing the capacitance risk threshold of a substation DC system, the method comprising:

[0006] Obtain a simplified calculation model of the relay protection device in the pre-established DC system of the substation, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the DC system of the substation.

[0007] The operating current that triggers the relay protection device is determined based on the rated current of the relay protection device.

[0008] The rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the substation DC system are input into the simplified calculation model. The simplified calculation model determines that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0009] Based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system, the capacitance risk threshold of the substation DC system is calculated.

[0010] Optionally, the step of determining, through the simplified calculation model, that the actual current flowing through the relay protection device during a single-point grounding event is not less than the duration of the operating current includes:

[0011] The initial current flowing through the relay protection device when a single-point grounding event occurs is calculated using the simplified calculation model.

[0012] Based on the operating current when the relay protection device is triggered and the initial current flowing through the relay protection device when a single-point grounding event occurs, it is determined that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0013] Optionally, the formula for calculating the initial current flowing through the relay protection device when a single-point grounding event occurs using the simplified calculation model is as follows:

[0014]

[0015]

[0016]

[0017] In the formula, C1 is the positive capacitor of the DC system, C2 is the negative capacitor of the DC system, U is the rated voltage of the DC system, and u c1 u is the rated voltage of the positive capacitor in a DC system. c2 R is the rated voltage of the negative capacitor in the DC system, R0 is the coil resistance of the relay protection device, R1 is the equivalent parallel resistance of the coil of the relay protection device, R2 is the circuit breaker tripping coil resistance, R3 is the DC system balance bridge resistance, R4 is the cable resistance, and R... ∑ For the combined resistance of the trip circuit, i R2 The current is the resistance of the circuit breaker trip coil, t is the time it takes for the current to flow through the relay protection device after a single-point ground fault occurs, and I is the initial current flowing through the relay protection device when the single-point ground fault occurs. TBJ '=i R2 (t=0), These are the initial conditions.

[0018] Optionally, the formula for calculating the capacitance risk threshold of the substation DC system based on the rated current and duration of the relay protection device, and the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system is as follows:

[0019]

[0020] C = C1 + C2

[0021] I TBJ '(T1)=0.4I1

[0022] R Σ =U / I2

[0023] In the formula, C is the capacitance risk threshold of the DC system, T1 is the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs, I1 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

[0024] This application also provides a device for analyzing the capacitance risk threshold of a substation DC system, including:

[0025] The data acquisition module is used to acquire a simplified calculation model of the relay protection device in the pre-established DC system of the substation, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the DC system of the substation.

[0026] The operating current determination module is used to determine the operating current that triggers the relay protection device to operate based on the rated current of the relay protection device;

[0027] The duration determination module is used to input the rated current of the relay protection device, the circuit breaker tripping current of the DC system of the substation, the rated voltage, and the balance bridge resistance into the simplified calculation model, and to determine the duration through which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0028] The capacitor risk threshold determination module is used to calculate the capacitor risk threshold of the substation DC system based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system.

[0029] Optionally, the duration determination module includes:

[0030] An initial current calculation module is used to calculate the initial current flowing through the relay protection device when a single-point grounding event occurs, using the simplified calculation model.

[0031] The duration calculation module is used to determine, based on the operating current when the relay protection device is triggered and the initial current flowing through the relay protection device when a single-point grounding event occurs, the duration for which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the operating current.

[0032] Optionally, the calculation formula of the initial current calculation module is:

[0033]

[0034]

[0035]

[0036] In the formula, C1 is the positive capacitor of the DC system, C2 is the negative capacitor of the DC system, U is the rated voltage of the DC system, and u c1 u is the rated voltage of the positive capacitor in a DC system. c2 R is the rated voltage of the negative capacitor in the DC system, R0 is the coil resistance of the relay protection device, R1 is the equivalent parallel resistance of the coil of the relay protection device, R2 is the circuit breaker tripping coil resistance, R3 is the DC system balance bridge resistance, R4 is the cable resistance, and R... ∑ For the combined resistance of the trip circuit, i R2 The current is the resistance of the circuit breaker trip coil, t is the time it takes for the current to flow through the relay protection device after a single-point ground fault occurs, and I is the initial current flowing through the relay protection device when the single-point ground fault occurs. TBJ '=i R2 (t=0), These are the initial conditions.

[0037] Optionally, the calculation formula for the capacitance risk threshold determination module is as follows:

[0038]

[0039] C = C1 + C2

[0040] I TBJ '(T1)=0.4I1

[0041] R Σ =U / I2

[0042] In the formula, C is the capacitance risk threshold of the DC system, T1 is the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs, I1 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

[0043] This application also provides a storage medium storing computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the substation DC system capacitance risk threshold analysis method as described in any of the above embodiments.

[0044] This application also provides a computer device, including: one or more processors, and memory;

[0045] The memory stores computer-readable instructions, which, when executed by the one or more processors, perform the steps of the substation DC system capacitance risk threshold analysis method as described in any of the above embodiments.

[0046] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0047] The method, apparatus, and storage medium for analyzing the capacitance risk threshold of a substation DC system provided in this application can first obtain a pre-established simplified calculation model of the relay protection device in the substation DC system, along with the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system. Then, based on the rated current of the relay protection device, the operating current when triggering the relay protection device is determined. Next, the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system are input into the simplified calculation model. The simplified calculation model determines that the duration for which the actual current flowing through the relay protection device during a single-point grounding event is not less than the operating current is determined. Finally, based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system, the capacitance risk threshold of the substation DC system is calculated. This process can efficiently and quickly calculate the capacitance risk threshold of the substation DC system, thereby ensuring the correct operation of the relay protection device, improving the accuracy of the relay protection device's operation, and ensuring power grid safety. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A flowchart illustrating a method for analyzing the capacitance risk threshold of a substation DC system, provided in an embodiment of this application;

[0050] Figure 2 Equivalent circuit diagram of a simplified calculation model of a relay protection device in a substation DC system provided in this application embodiment;

[0051] Figure 3 The graph showing the change of current flowing through the TBJ block over time is provided in the embodiments of this application.

[0052] Figure 4 A schematic diagram of the structure of a substation DC system capacitor risk threshold analysis device provided in this application embodiment;

[0053] Figure 5 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of this application. Detailed Implementation

[0054] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] As the last line of defense for the safe and stable operation of the power grid, relay protection devices pose a significant threat to grid safety if their operation is flawed. Therefore, it is necessary to design a method for analyzing and calculating the capacitance risk threshold of substation DC systems to improve the accuracy of relay protection device operation and ensure grid safety. Based on this, this application proposes the following technical solution, as detailed below:

[0056] In one embodiment, such as Figure 1 As shown, Figure 1 This application provides a flowchart illustrating a method for analyzing the capacitance risk threshold of a substation DC system, as illustrated in an embodiment of the present application. The method may include:

[0057] S110: Obtain a simplified calculation model of the relay protection device in the pre-established DC system of the substation, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the DC system of the substation.

[0058] In this step, when analyzing the capacitance risk threshold of the substation DC system, a simplified calculation model of the relay protection device in the substation DC system can be obtained first, such as... Figure 2 As shown, Figure 2 Equivalent circuit diagram of a simplified calculation model of a relay protection device in a substation DC system provided in this application embodiment; Figure 2 In the context of a substation relay protection device (TBJ) experiencing a single-point grounding event in its input circuit, the distributed capacitance C of the positive line is typically considered. P The coil of relay TBJ is charged through the distributed capacitance C of the negative terminal line. N A simplified calculation model is established by discharging the coil of relay TBJ. In the equivalent circuit diagram of the simplified calculation model, k closing represents a single-point grounding event. Figure 2 The area within the dashed box is the TBJ current holding relay block (including the TBJ and its parallel devices). When setting the TBJ operating current, the manufacturer considers the TBJ block as a whole.

[0059] Depend on Figure 2 It is evident that the capacitance risk threshold of a substation DC system varies under different operating conditions (different circuit breaker tripping currents and TBJ module rated currents). Therefore, in order to analyze the capacitance risk threshold of a substation DC system through a simplified calculation model, it is necessary to obtain the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system through on-site measurements by maintenance personnel, and to consult the protection manufacturer regarding the rated current of the TBJ module. This information will allow for the simplified calculation model to analyze the capacitance risk threshold of the substation DC system.

[0060] S120: Determine the operating current when the relay protection device is triggered based on the rated current of the relay protection device.

[0061] In this step, after obtaining the rated current of the relay protection device through S110, the operating current when the relay protection device is triggered can be determined based on the rated current of the relay protection device. In this way, it can be further determined that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0062] Understandably, based on the analysis of existing tripping circuits, the rated current of the TBJ module (denoted as I1) in field engineering is usually set in 0.5A increments according to the circuit breaker's tripping current, and the operating current is usually taken as 40% of the rated current I1. The TBJ operating time is generally 6-7ms, and the theoretical analysis takes the operating time as 5ms. Therefore, the duration of the current flowing through the TBJ module when a single-point ground fault occurs (denoted as T1) must be 5ms to meet the minimum requirement for TBJ operation. If the rated current I1 of the TBJ module is 1A, then as long as the current flowing through the TBJ module at time T1 (5ms) when a single-point ground fault occurs is not less than 0.4A, the TBJ operation condition will be met.

[0063] Based on this, this application can set the operating current when triggering the relay protection device to 0.4I1, given that the rated current I1 of the relay protection device is determined.

[0064] S130: Input the rated current of the relay protection device, the circuit breaker tripping current of the DC system of the substation, the rated voltage, and the balance bridge resistance into the simplified calculation model. The simplified calculation model determines that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0065] In this step, a simplified calculation model is obtained through S110, along with the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system. After determining the operating current when the relay protection device is triggered through S120, this application can input the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system into the simplified calculation model. The simplified calculation model determines that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0066] It should be noted that whether the TBJ (Block Tunnel Breaker) will operate depends on the duration for which the current flowing through the TBJ block is not less than its operating current. If the duration reaches the TBJ operating time, the TBJ will operate. Therefore, as long as the TBJ operating time t is known, the actual current flowing through the TBJ block at time t when a single-point ground fault occurs can be calculated. Then, by comparing this current with the operating current value of the TBJ block, it can be determined whether the circuit breaker will operate when a single-point ground fault occurs.

[0067] Indicatively, such as Figure 3 As shown, Figure 3 The graph showing the change of current flowing through the TBJ block over time is provided for embodiments of this application. This application can select typical parameters to obtain the curve of the change of current flowing through the TBJ block when a single-point grounding event occurs under a simplified calculation model. This application can assume that the rated voltage U of the DC system is 220V, the circuit breaker tripping current is 1A, and the combined resistance R of the tripping circuit is... Σ The current is 220Ω; the DC system balance bridge resistor R3 is 40kΩ; the DC system positive capacitor C1 and DC system negative capacitor C2 are 50μF. The curve showing the change of current flowing through the TBJ module over time is as follows: Figure 3 As shown, by Figure 3 It can be seen that, under the simplified calculation model, the current flowing through the TBJ block decays over time when a single-point grounding event occurs.

[0068] Since the current flowing through the TBJ block during a single-point ground fault decays over time in the simplified calculation model, knowing the TBJ's operating time t allows us to calculate the actual current flowing through the TBJ block at time t when the single-point ground fault occurs. Comparing this current with the TBJ block's operating current value allows us to determine whether the circuit breaker will trip during a single-point ground fault. In substation operation, voltage, inductance, and resistance parameters are fixed, while capacitance parameters can change due to modifications to substation insulation monitoring devices or other equipment. Therefore, this application can calculate the capacitance risk threshold of the DC system based on other parameters in the simplified calculation model.

[0069] S140: Calculate the capacitance risk threshold of the substation DC system based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system.

[0070] In this step, after determining through S130 that the duration of the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current, the capacitance risk threshold of the substation DC system can be calculated based on the rated current and duration of the relay protection device in the simplified calculation model, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system.

[0071] In the above embodiments, when analyzing the capacitance risk threshold of a substation DC system, a simplified calculation model of the relay protection device in the substation DC system can be obtained first, along with the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system. Then, the operating current triggering the relay protection device is determined based on its rated current. Next, the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system are input into the simplified calculation model. The simplified calculation model determines the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs. Finally, based on the rated current and duration of the relay protection device, and the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system, the capacitance risk threshold of the substation DC system is calculated. This process can efficiently and quickly calculate the capacitance risk threshold of the substation DC system, thereby ensuring the correct operation of the relay protection device, improving the accuracy of the relay protection device's operation, and ensuring power grid safety.

[0072] In one embodiment, determining, through the simplified calculation model, that the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs may include:

[0073] S131: Calculate the initial current flowing through the relay protection device when a single-point grounding event occurs using the simplified calculation model.

[0074] S132: Based on the operating current when the relay protection device is triggered to operate, and the initial current flowing through the relay protection device when a single-point grounding event occurs, determine that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0075] In this embodiment, after obtaining the pre-established simplified calculation model related to the relay protection device, the relevant calculation formula for the current flowing through the TBJ block when a single-point grounding event occurs under the simplified calculation model can be obtained based on the zero-state response of the simplified calculation model under DC excitation. The initial current flowing through the relay protection device when a single-point grounding event occurs can be calculated using this calculation formula. Furthermore, since this application can directly determine the operating current when the relay protection device is triggered based on the rated current of the relay protection device, the duration during which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the operating current can be derived by reverse calculation based on the initial current and operating current of the relay protection device. Then, the capacitance risk threshold of the DC system can be calculated based on this duration and other parameters.

[0076] In one embodiment, the formula for calculating the initial current flowing through the relay protection device when a single-point grounding event occurs using the simplified calculation model is as follows:

[0077]

[0078]

[0079]

[0080] In the formula, C1 is the positive capacitor of the DC system, C2 is the negative capacitor of the DC system, U is the rated voltage of the DC system, and u c1 u is the rated voltage of the positive capacitor in a DC system. c2 R is the rated voltage of the negative capacitor in the DC system, R0 is the coil resistance of the relay protection device, R1 is the equivalent parallel resistance of the coil of the relay protection device, R2 is the circuit breaker tripping coil resistance, R3 is the DC system balance bridge resistance, R4 is the cable resistance, and R... ∑ For the combined resistance of the trip circuit, i R2 The current is the resistance of the circuit breaker trip coil, t is the time it takes for the current to flow through the relay protection device after a single-point ground fault occurs, and I is the initial current flowing through the relay protection device when the single-point ground fault occurs. TBJ '=i R2 (t=0), These are the initial conditions.

[0081] The initial current flowing through the relay protection device when a single-point grounding event occurs can be determined from the above formula. Since the operating current triggering the relay protection device is known in this application, the value of this operating current is substituted into i. R2 This allows us to determine that the actual current flowing through the relay protection device during a single-point grounding event is not less than the duration of the operating current.

[0082] In one embodiment, the formula for calculating the capacitance risk threshold of the substation DC system based on the rated current and duration of the relay protection device, and the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system is as follows:

[0083]

[0084] C = C1 + C2

[0085] I TBJ '(T1)=0.4I1

[0086] R Σ =U / I2

[0087] In the formula, C is the capacitance risk threshold of the DC system, T1 is the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs, I1 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

[0088] In one specific implementation, this application can be achieved by measuring the rated voltage U of the DC system in the field engineering and the circuit breaker tripping current I2 (the combined resistance R of the tripping circuit). ∑ =U / I2), DC system balancing bridge resistor R3, let the current I flowing through the TBJ block at time T1 when a single-point ground fault occurs be... TBJ The risk threshold of the DC system capacitor under the measured condition can be calculated by '(T1)=0.4I1.

[0089] Schematic, as shown in the table below, Table 1 presents the capacitance risk thresholds of a 220V DC system under different operating conditions (different circuit breaker tripping currents and TBJ block rated currents). The rated voltage U of the DC system is 220V, and the DC system balancing bridge resistor R3 is 40kΩ.

[0090]

[0091] Table 1 shows the capacitor risk thresholds for a 220V DC system under a simplified calculation model.

[0092] As shown in Table 1, when the on-site maintenance personnel measured the circuit breaker tripping current I2 to be 0.6A and consulted the protection manufacturer, the rated current I1 of the TBJ module was set to 0.5A. In order to prevent the risk of circuit breaker maloperation when one point of the input circuit of the substation relay protection device TBJ is grounded, the capacitance value of the on-site 220V DC system should not exceed 33μF.

[0093] The substation DC system capacitor risk threshold analysis device provided in the embodiments of this application is described below. The substation DC system capacitor risk threshold analysis device described below can be referred to in correspondence with the substation DC system capacitor risk threshold analysis method described above.

[0094] In one embodiment, such as Figure 4 As shown, Figure 4 This application provides a schematic diagram of the structure of a substation DC system capacitor risk threshold analysis device according to an embodiment of the present application. The present application also provides a substation DC system capacitor risk threshold analysis device, which may include a data acquisition module 210, an operating current determination module 220, a duration determination module 230, and a capacitor risk threshold determination module 240, specifically including the following:

[0095] The data acquisition module 210 is used to acquire a simplified calculation model of the relay protection device in the substation DC system, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the substation DC system.

[0096] The operating current determination module 220 is used to determine the operating current that triggers the operation of the relay protection device based on the rated current of the relay protection device.

[0097] The duration determination module 230 is used to input the rated current of the relay protection device, the circuit breaker tripping current of the DC system of the substation, the rated voltage, and the balance bridge resistance into the simplified calculation model, and to determine, through the simplified calculation model, that the duration during which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current.

[0098] The capacitor risk threshold determination module 240 is used to calculate the capacitor risk threshold of the substation DC system based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage and balance bridge resistance of the substation DC system.

[0099] In the above embodiments, when analyzing the capacitance risk threshold of a substation DC system, a simplified calculation model of the relay protection device in the substation DC system can be obtained first, along with the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system. Then, the operating current triggering the relay protection device is determined based on its rated current. Next, the rated current of the relay protection device, the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system are input into the simplified calculation model. The simplified calculation model determines the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs. Finally, based on the rated current and duration of the relay protection device, and the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system, the capacitance risk threshold of the substation DC system is calculated. This process can efficiently and quickly calculate the capacitance risk threshold of the substation DC system, thereby ensuring the correct operation of the relay protection device, improving the accuracy of the relay protection device's operation, and ensuring power grid safety.

[0100] In one embodiment, the duration determination module includes:

[0101] An initial current calculation module is used to calculate the initial current flowing through the relay protection device when a single-point grounding event occurs, using the simplified calculation model.

[0102] The duration calculation module is used to determine, based on the operating current when the relay protection device is triggered and the initial current flowing through the relay protection device when a single-point grounding event occurs, the duration for which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the operating current.

[0103] In one embodiment, the calculation formula of the initial current calculation module is:

[0104]

[0105]

[0106]

[0107] In the formula, C1 is the positive capacitor of the DC system, C2 is the negative capacitor of the DC system, U is the rated voltage of the DC system, and u c1 u is the rated voltage of the positive capacitor in a DC system. c2 R is the rated voltage of the negative capacitor in the DC system, R0 is the coil resistance of the relay protection device, R1 is the equivalent parallel resistance of the coil of the relay protection device, R2 is the circuit breaker tripping coil resistance, R3 is the DC system balance bridge resistance, R4 is the cable resistance, and R... ∑ For the combined resistance of the trip circuit, iR2 The current is the resistance of the circuit breaker trip coil, t is the time it takes for the current to flow through the relay protection device after a single-point ground fault occurs, and I is the initial current flowing through the relay protection device when the single-point ground fault occurs. TBJ '=i R2 (t=0), These are the initial conditions.

[0108] In one embodiment, the calculation formula for the capacitance risk threshold determination module is:

[0109]

[0110] C = C1 + C2

[0111] I TBJ '(T1)=0.4I1

[0112] R Σ =U / I2

[0113] In the formula, C is the capacitance risk threshold of the DC system, T1 is the duration during which the actual current flowing through the relay protection device is not less than the operating current when a single-point grounding event occurs, I1 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

[0114] In one embodiment, this application also provides a storage medium storing computer-readable instructions that, when executed by one or more processors, cause the one or more processors to perform the steps of the substation DC system capacitance risk threshold analysis method as described in any of the above embodiments.

[0115] In one embodiment, this application also provides a computer device, including: one or more processors, and memory.

[0116] The memory stores computer-readable instructions, which, when executed by the one or more processors, perform the steps of the substation DC system capacitance risk threshold analysis method as described in any of the above embodiments.

[0117] Indicatively, such as Figure 5 As shown, Figure 5 This is a schematic diagram of the internal structure of a computer device 300 provided in an embodiment of this application. The computer device 300 can be provided as a server. (Refer to...) Figure 5The computer device 300 includes a processing component 302, which further includes one or more processors, and memory resources represented by memory 301 for storing instructions, such as application programs, that can be executed by the processing component 302. The application programs stored in memory 301 may include one or more modules, each corresponding to a set of instructions. Furthermore, the processing component 302 is configured to execute instructions to perform the substation DC system capacitance risk threshold analysis method of any of the above embodiments.

[0118] The computer device 300 may also include a power supply component 303 configured to perform power management of the computer device 300, a wired or wireless network interface 304 configured to connect the computer device 300 to a network, and an input / output (I / O) interface 305. The computer device 300 may operate on an operating system stored in memory 301, such as Windows Server™, Mac OS X™, Unix™, Linux™, Free BSD™, or similar.

[0119] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0120] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for analyzing the capacitance risk threshold of a substation DC system, characterized in that, The method includes: Obtain a simplified calculation model of the relay protection device in the pre-established DC system of the substation, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the DC system of the substation. The operating current that triggers the relay protection device is determined based on the rated current of the relay protection device. The rated current of the relay protection device, the circuit breaker tripping current, the rated voltage, and the balance bridge resistance of the substation DC system are input into the simplified calculation model. The simplified calculation model determines that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current. Based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system, calculate the capacitance risk threshold of the substation DC system. The determination, made through the simplified calculation model, that the actual current flowing through the relay protection device during a single-point grounding event is not less than the duration of the operating current includes: The initial current flowing through the relay protection device when a single-point grounding event occurs is calculated using the simplified calculation model. Based on the operating current when the relay protection device is triggered and the initial current flowing through the relay protection device when a single-point grounding event occurs, it is determined that the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current. The formula for calculating the initial current flowing through the relay protection device when a single-point grounding event occurs using the simplified calculation model is as follows: In the formula, It is the positive capacitor of the DC system. It is the negative capacitor of the DC system. The rated voltage of the DC system. This is the rated voltage of the positive capacitor in the DC system. This is the rated voltage of the negative capacitor in the DC system. For the coil resistance of the relay protection device, The equivalent resistance in parallel with the coil of the relay protection device. The resistance of the circuit breaker trip coil. For the DC system's balancing bridge resistor, For cable resistance, For the combined resistance of the trip circuit, The current is the resistance of the circuit breaker's tripping coil. The time it takes for the current to flow through the relay protection device after a single-point grounding event occurs, and the initial current I flowing through the relay protection device at the time of the single-point grounding event. TBJ ’ =i R2 ( =0), These are the initial conditions; The formula for calculating the capacitance risk threshold of the substation DC system based on the rated current and duration of the relay protection device, and the circuit breaker tripping current, rated voltage, and balance bridge resistance of the substation DC system is as follows: C = C1 + C2 I TBJ ’ （ ）=0.4 R Σ =U / I2 In the formula, The capacitance risk threshold for a DC system. The actual current flowing through the relay protection device during a single-point grounding event must not be less than the duration of the operating current. I0 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

2. A device for analyzing the capacitance risk threshold of a substation DC system, characterized in that, include: The data acquisition module is used to acquire a simplified calculation model of the relay protection device in the pre-established DC system of the substation, as well as the rated current of the relay protection device, the circuit breaker tripping current, the rated voltage and the balance bridge resistance of the DC system of the substation. The operating current determination module is used to determine the operating current that triggers the relay protection device to operate based on the rated current of the relay protection device. The duration determination module is used to input the rated current of the relay protection device, the circuit breaker tripping current of the DC system of the substation, the rated voltage, and the balance bridge resistance into the simplified calculation model, and to determine the duration through which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the duration of the operating current. The capacitor risk threshold determination module is used to calculate the capacitor risk threshold of the substation DC system based on the rated current and duration of the relay protection device, as well as the circuit breaker tripping current, rated voltage and balance bridge resistance of the substation DC system. The duration determination module includes: An initial current calculation module is used to calculate the initial current flowing through the relay protection device when a single-point grounding event occurs, using the simplified calculation model. The duration calculation module is used to determine, based on the operating current when the relay protection device is triggered to operate and the initial current flowing through the relay protection device when a single-point grounding event occurs, the duration for which the actual current flowing through the relay protection device when a single-point grounding event occurs is not less than the operating current. The calculation formula of the initial current calculation module is as follows: In the formula, It is the positive capacitor of the DC system. It is the negative capacitor of the DC system. The rated voltage of the DC system. This is the rated voltage of the positive capacitor in the DC system. This is the rated voltage of the negative capacitor in the DC system. For the coil resistance of the relay protection device, The equivalent resistance in parallel with the coil of the relay protection device. The resistance of the circuit breaker trip coil. For the DC system's balancing bridge resistor, For cable resistance, For the combined resistance of the trip circuit, The current is the resistance of the circuit breaker's tripping coil. The time it takes for the current to flow through the relay protection device after a single-point grounding event occurs, and the initial current I flowing through the relay protection device at the time of the single-point grounding event. TBJ ’ =i R2 ( =0), These are the initial conditions; The calculation formula for the capacitance risk threshold determination module is as follows: C = C1 + C2 I TBJ ’ （ ）=0.4 R Σ =U / I2 In the formula, The capacitance risk threshold for a DC system. The actual current flowing through the relay protection device during a single-point grounding event must not be less than the duration of the operating current. I0 is the rated current of the relay protection device, and I2 is the circuit breaker tripping current of the DC system.

3. A storage medium, characterized in that: The storage medium stores computer-readable instructions, which, when executed by one or more processors, cause the one or more processors to perform the steps of the substation DC system capacitance risk threshold analysis method as described in claim 1.

4. A computer device, characterized in that, include: One or more processors, and memory; The memory stores computer-readable instructions, which, when executed by the one or more processors, perform the steps of the substation DC system capacitance risk threshold analysis method as described in claim 1.

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