Method and system for adaptive setting of the differential protection ratio braking coefficient

Abstract

The present application relates to the technical field of power system relay protection, and provides a multi-terminal differential protection method and system of adaptive adjustment of a ratio restraint coefficient, wherein the method comprises: confirming the actual number of operating terminals of a multi-terminal line according to the on-off state of a communication channel and electrical parameters; taking the actual number of operating terminals as an additional parameter to construct a variable ratio restraint coefficient value equation with inverse proportion characteristics; obtaining an adaptive adjustment ratio restraint coefficient equation based on the variable ratio restraint coefficient value equation, and realizing adaptive adjustment of the restraint coefficient under different network topologies according to the adaptive adjustment ratio restraint coefficient equation. The present application can further improve the adaptive degree of differential protection, introduces the actual number of operating terminals of a system into the restraint coefficient, and the protection device can automatically adjust the value of the restraint coefficient according to the number of accessed channels, so as to improve the reliability and sensitivity of differential protection. The present application solves the problem of insufficient sensitivity of multi-terminal line differential protection of a new energy station under complex fault conditions.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection technology, and in particular to a multi-terminal differential protection method and system with an adaptive adjustment ratio braking coefficient. Background Technology

[0002] With the rapid development of new energy sources, the operation of power systems is also evolving. Traditional two-terminal line systems are mainly designed for point-to-point power transmission, suitable for situations where energy distribution is concentrated and demand locations are clearly defined. However, with the large-scale construction of new energy sources such as wind power and photovoltaics, especially in remote areas, these traditional systems face new challenges. The distributed and intermittent nature of new energy sources requires the power grid to flexibly handle energy production at different locations and times. Multi-terminal line systems provide this flexibility, allowing power to be transmitted from multiple generation points to different load centers and flexibly redistributed within the system to adapt to the volatility of new energy sources. However, due to the multi-branch structure of the lines, the distribution and characteristics of fault currents are more complex than those of two-terminal lines, making differential protection suitable for traditional two-terminal lines unsuitable. Therefore, there is an urgent need for current differential protection suitable for multi-terminal lines. Summary of the Invention

[0003] The purpose of this invention is to solve at least one technical problem in the background art and to provide a multi-terminal differential protection method and system with adaptive adjustment ratio braking coefficient.

[0004] To achieve the above objectives, the present invention provides a multi-terminal differential protection method with adaptive adjustment ratio braking coefficient, comprising:

[0005] Confirm the actual number of operational terminals of the multi-terminal line based on the communication channel's activation / deactivation status and electrical parameters;

[0006] The actual number of operational terminals is used as an additional parameter to construct an equation for the value of the variable ratio braking coefficient with inverse bit properties.

[0007] Based on the variable ratio braking coefficient value equation, the adaptive adjustment ratio braking coefficient equation is obtained;

[0008] Based on the adaptive adjustment ratio braking coefficient equation, the braking coefficient is adaptively adjusted under different network topologies.

[0009] According to one aspect of the present invention, the actual number of operating terminals of a multi-terminal line is determined based on the communication channel's activation / deactivation status and electrical parameters:

[0010] The system monitors whether the channel pressure plate of the communication channel is engaged. When engaged, the endpoints of the corresponding lines are counted as operational endpoints. Then, the electrical parameter status of the line endpoints counted as operational endpoints is confirmed. If the electrical parameter status matches the actual operating status, the line endpoints counted as operational endpoints are confirmed as the actual operational endpoints.

[0011] According to one aspect of the invention, the equation for the variable ratio braking coefficient with inverse bit properties is:

[0012]

[0013] Where K(n) is the ratio braking coefficient, n is the actual number of terminals in operation, and a, b and c are adjustment coefficients, which are 1.2, -7 and 1 respectively.

[0014] According to one aspect of the present invention, an adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, comprising:

[0015] The inverse braking coefficient equation is used to adjust the value of the ratio braking coefficient with time as the variable.

[0016] Combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, an adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived.

[0017] According to one aspect of the invention, the method of employing an anti-braking coefficient equation, with time as the variable, adjusts the value of the ratio braking coefficient as follows:

[0018]

[0019] Where K(t) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the starting threshold of K(t), t is time, L is the IEC constant, and a is the IEC constant.

[0020] According to one aspect of the present invention, combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, the adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived as follows:

[0021]

[0022] Where K(t,n) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the start threshold of K(t,n), t is time, n is the actual number of operating terminals, L is the IEC constant, and a is the IEC constant.

[0023] According to one aspect of the present invention, an adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, comprising:

[0024] The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation:

[0025]

[0026] Calculate the error of the target braking coefficient and the rate of change of the error over time:

[0027] Δe(t,n)=K(n)-K(t-1,n);

[0028] d(Δe(t,n))=Δe(t,n)-Δe(t-1,n);

[0029] Based on the error of the target braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive engagement ratio braking coefficient equation is obtained:

[0030]

[0031] Where K(n) is the ratio braking coefficient, t is time, and K(t,n) is the ratio braking coefficient at time t based on the actual number of operating terminals n. p K I and K D Hereinafter, we have the error coefficient, the cumulative error coefficient, and the rate of change of error coefficient. Δe(t,n) is the error value of the ratio braking coefficient K(n) relative to the target, and d(Δe(t,n)) is the rate of change of error with time t.

[0032] To achieve the above objectives, the present invention also provides a multi-terminal differential protection system with adaptive adjustment ratio braking coefficient, comprising:

[0033] The actual number of operational terminals confirmation module confirms the actual number of multi-terminal lines in operation based on the communication channel's activation / deactivation status and electrical parameters.

[0034] The variable ratio braking coefficient value equation construction module constructs a variable ratio braking coefficient value equation with inverse bit properties by using the actual number of operating terminals as an additional parameter.

[0035] The adaptive allocation ratio braking coefficient equation construction module obtains the adaptive allocation ratio braking coefficient equation based on the variable ratio braking coefficient value equation, and realizes the adaptive adjustment of the braking coefficient under different network topologies according to the adaptive allocation ratio braking coefficient equation.

[0036] To achieve the above objectives, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described above.

[0037] To achieve the above objectives, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described above.

[0038] According to the present invention, the adaptiveness of differential protection can be further improved by incorporating the actual number of operating terminals n into the braking coefficient. The protection device can automatically adjust the braking coefficient k value according to the number of connected channels, thereby improving the reliability and sensitivity of differential protection. This solves the problem of insufficient sensitivity of differential protection for multi-terminal lines in new energy power stations under complex fault conditions, and can significantly improve the reliability of multi-point T-connected lines in new energy power stations. Attached Figure Description

[0039] Figure 1 A flowchart illustrating a multi-terminal differential protection method with adaptive adjustment ratio braking coefficient according to an embodiment of the present invention is shown.

[0040] Figure 2 This is a schematic diagram of the ratio braking coefficient curve under the 2-3 end operation mode;

[0041] Figure 3 This is a schematic diagram of the ratio braking coefficient curve under the 4-6 end operation mode;

[0042] Figure 4 This is a schematic diagram of the ratio braking coefficient curve under operating modes of 7 terminals and above;

[0043] Figure 5 This is a schematic diagram of the braking coefficient based on the terminal number adjustment ratio;

[0044] Figure 6 This is a schematic diagram of the braking coefficient based on the number of terminals and the time allocation ratio;

[0045] Figure 7 Schematic diagram of adaptive adjustment based on target braking coefficient. Detailed Implementation

[0046] The invention will now be discussed with reference to exemplary embodiments. It should be understood that the described embodiments are merely intended to enable those skilled in the art to better understand and thus implement the invention, and are not intended to imply any limitation on the scope of the invention.

[0047] As used herein, the term "comprising" and its variations are to be interpreted as open-ended terms meaning "including but not limited to". The term "based on" is to be interpreted as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be interpreted as "at least one embodiment".

[0048] Figure 1 A flowchart illustrating a multi-terminal differential protection method for adaptively adjusting the braking coefficient according to an embodiment of the present invention is shown. Figure 1 As shown, in this embodiment, the multi-terminal differential protection method for adaptively adjusting the braking coefficient includes:

[0049] Confirm the actual number of operational terminals of the multi-terminal line based on the communication channel's activation / deactivation status and electrical parameters;

[0050] The actual number of operating terminals is used as an additional parameter to construct an equation for the variable ratio braking coefficient, which has an inverse proportional characteristic (the braking coefficient decreases as the number of terminals and time increase).

[0051] Based on the variable ratio braking coefficient value equation, an adaptive adjustment ratio braking coefficient equation is obtained. According to the adaptive adjustment ratio braking coefficient equation, the braking coefficient is adaptively adjusted under different network topologies.

[0052] Furthermore, according to one embodiment of the present invention, the actual number of operating terminals of the multi-terminal line is determined based on the communication channel's activation / deactivation status and electrical parameters:

[0053] The system monitors whether the channel pressure plate of the communication channel is engaged. When engaged, the endpoints of the corresponding lines are counted as operational endpoints. Then, the electrical parameter status of the line endpoints counted as operational endpoints is confirmed. If the electrical parameter status matches the actual operating status, the line endpoints counted as operational endpoints are confirmed as the actual operational endpoints.

[0054] Furthermore, according to one embodiment of the present invention, the equation for the variable ratio braking coefficient with inverse bit properties is as follows:

[0055]

[0056] Where K(n) is the ratio braking coefficient, n is the actual number of operating terminals, and a, b and c are adjustment coefficients, which are 1.2, -7 and 1 respectively. By adjusting the values ​​of a, b and c, the dynamic adjustment curve of the ratio braking coefficient after the fault can be obtained.

[0057] Furthermore, according to one embodiment of the present invention, the adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, including:

[0058] The inverse braking coefficient equation is used to adjust the value of the ratio braking coefficient with time as the variable.

[0059] Combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, an adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived.

[0060] Furthermore, according to one embodiment of the present invention, an anti-braking coefficient equation is used, with time as the variable to adjust the value of the ratio braking coefficient as follows:

[0061]

[0062] Where K(t) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the starting threshold of K(t), t is time, L is the IEC constant, and a is the IEC constant.

[0063] Furthermore, according to one embodiment of the present invention, by combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, the adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived as follows:

[0064]

[0065] Where K(t,n) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the start threshold of K(t,n), t is time, n is the actual number of operating terminals, L is the IEC constant, and a is the IEC constant.

[0066] Furthermore, according to one embodiment of the present invention, the adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, including:

[0067] The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation:

[0068]

[0069] Calculate the error of the target braking coefficient and the rate of change of the error over time:

[0070] Δe(t,n)=K(n)-K(t-1,n);

[0071] d(Δe(t,n))=Δe(t,n)-Δe(t-1,n);

[0072] Based on the error of the target braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive engagement ratio braking coefficient equation is obtained:

[0073]

[0074] Where K(n) is the ratio braking coefficient, t is time, and K(t,n) is the ratio braking coefficient at time t based on the actual number of operating terminals n. p K I and K DHereinafter, we have the error coefficient, the cumulative error coefficient, and the rate of change of error coefficient. Δe(t,n) is the error value of the ratio braking coefficient K(n) relative to the target, and d(Δe(t,n)) is the rate of change of error with time t.

[0075] According to the above-described solution of the present invention, the present invention can further improve the adaptability of differential protection by incorporating the actual number of operating terminals n into the braking coefficient. The protection device can automatically adjust the braking coefficient k value according to the number of connected channels, thereby improving the reliability and sensitivity of differential protection. This solves the problem of insufficient sensitivity of differential protection for multi-terminal lines in new energy power stations under complex fault conditions, and can significantly improve the reliability of multi-point T-connected lines in new energy power stations.

[0076] Furthermore, to achieve the above objectives, the present invention also provides a multi-terminal differential protection system with adaptive adjustment ratio braking coefficient, comprising:

[0077] The actual number of operational terminals confirmation module confirms the actual number of multi-terminal lines in operation based on the communication channel's activation / deactivation status and electrical parameters.

[0078] The variable ratio braking coefficient value equation construction module constructs a variable ratio braking coefficient value equation with inverse bit properties by using the actual number of operating terminals as an additional parameter.

[0079] The adaptive allocation ratio braking coefficient equation construction module obtains the adaptive allocation ratio braking coefficient equation based on the variable ratio braking coefficient value equation, and realizes the adaptive adjustment of the braking coefficient under different network topologies according to the adaptive allocation ratio braking coefficient equation.

[0080] Furthermore, according to one embodiment of the present invention, the actual number of operating terminals of the multi-terminal line is determined based on the communication channel's activation / deactivation status and electrical parameters:

[0081] The system monitors whether the channel pressure plate of the communication channel is engaged. When engaged, the endpoints of the corresponding lines are counted as operational endpoints. Then, the electrical parameter status of the line endpoints counted as operational endpoints is confirmed. If the electrical parameter status matches the actual operating status, the line endpoints counted as operational endpoints are confirmed as the actual operational endpoints.

[0082] Furthermore, according to one embodiment of the present invention, the equation for the variable ratio braking coefficient with inverse bit properties is as follows:

[0083]

[0084] Where K(n) is the ratio braking coefficient, n is the actual number of operating terminals, and a, b and c are adjustment coefficients, which are 1.2, -7 and 1 respectively. By adjusting the values ​​of a, b and c, the dynamic adjustment curve of the ratio braking coefficient after the fault can be obtained.

[0085] Furthermore, according to one embodiment of the present invention, the adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, including:

[0086] The inverse braking coefficient equation is used to adjust the value of the ratio braking coefficient with time as the variable.

[0087] Combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, an adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived.

[0088] Furthermore, according to one embodiment of the present invention, an anti-braking coefficient equation is used, with time as the variable to adjust the value of the ratio braking coefficient as follows:

[0089]

[0090] Where K(t) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the starting threshold of K(t), t is time, L is the IEC constant, and a is the IEC constant.

[0091] Furthermore, according to one embodiment of the present invention, by combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, the adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived as follows:

[0092]

[0093] Where K(t,n) is the ratio braking coefficient, K1 is the IEC constant, K2 is the adjustment coefficient, K3 is the start threshold of K(t,n), t is time, n is the actual number of operating terminals, L is the IEC constant, and a is the IEC constant.

[0094] Furthermore, according to one embodiment of the present invention, the adaptive allocation ratio braking coefficient equation is obtained based on the variable ratio braking coefficient value equation, including:

[0095] The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation:

[0096]

[0097] Calculate the error of the target braking coefficient and the rate of change of the error over time:

[0098] Δe(t,n)=K(n)-K(t-1,n);

[0099] d(Δe(t,n))=Δe(t,n)-Δe(t-1,n);

[0100] Based on the error of the target braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive engagement ratio braking coefficient equation is obtained:

[0101]

[0102] Where K(n) is the ratio braking coefficient, t is time, and K(t,n) is the ratio braking coefficient at time t based on the actual number of operating terminals n. p K I and K D Hereinafter, we have the error coefficient, the cumulative error coefficient, and the rate of change of error coefficient. Δe(t,n) is the error value of the ratio braking coefficient K(n) relative to the target, and d(Δe(t,n)) is the rate of change of error with time t.

[0103] According to the above-described solution of the present invention, the present invention can further improve the adaptability of differential protection by incorporating the actual number of operating terminals n into the braking coefficient. The protection device can automatically adjust the braking coefficient k value according to the number of connected channels, thereby improving the reliability and sensitivity of differential protection. This solves the problem of insufficient sensitivity of differential protection for multi-terminal lines in new energy power stations under complex fault conditions, and can significantly improve the reliability of multi-point T-connected lines in new energy power stations.

[0104] Furthermore, to achieve the above objectives, the present invention also provides an electronic device, including a processor, a memory, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described above.

[0105] Furthermore, to achieve the above objectives, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described above.

[0106] Based on the above-described solution of the present invention, the solution of the present invention will be described in detail below with reference to the accompanying drawings in a specific embodiment.

[0107] Example 1

[0108] It should be noted that differential protection operates on the principle of comparing currents. In a normal power system, the total current flowing into and out of a region or device should be equal. Differential protection works by measuring and comparing the currents flowing into and out of the protected area. If a current imbalance is detected, i.e., the inflow current is greater than the outflow current, this usually indicates a short circuit or other abnormal condition.

[0109] The differential equation for differential protection can be described as follows:

[0110]

[0111] Among them I d For differential current, This represents the current at the i-th terminal.

[0112] Furthermore, the differential protection device will be set with a current differential value I. qd When the actual measured current difference exceeds this threshold (current differential value I), qd When a fault occurs, the protection device will activate, quickly disconnecting the faulty section via a circuit breaker or other switching equipment, thereby protecting other parts of the power system from damage. This protection method is highly selective, capable of quickly and accurately identifying and isolating faults, reducing the impact on other parts of the system, and improving the reliability and safety of the power system. The starting current threshold, I, is set based on the maximum unbalanced differential current during normal operation. d >I qd .

[0113] Furthermore, a single differential current criterion may not guarantee the correct operation of the protection device. If a short circuit occurs outside the protection zone, the fault current should be several times the normal current. This leads to a significant increase in the differential current due to CT error, exceeding the differential operating setting and causing maloperation. To avoid this, a braking current is often used to ensure the reliability of the protection. Therefore, the braking current I adopted in Embodiment 1 of this invention... r for:

[0114]

[0115] Based on braking current I r The ratio braking equation of Embodiment 1 of the present invention is:

[0116]

[0117] In practice, in multi-terminal line differential protection applications, the calculation of the braking current becomes more complex as the number of system terminals increases. This is because the topology of multi-terminal lines leads to a more complex distribution and flow of current within the system. Especially during internal faults, multiple terminals may supply additional current to the fault point, thus increasing the value of the braking current. To ensure that the differential protection device can operate reliably during faults within the zone, the braking coefficient K needs to be appropriately adjusted.

[0118] The braking coefficient K is a key parameter in differential protection, determining the ratio of the braking current to the differential current. In multi-terminal lines, the selection of the braking coefficient K requires a balance between the protection's sensitivity and reliability. If the braking coefficient K is too large, the protection device may be unable to overcome the large braking current during faults within the protection zone, leading to malfunctions. Conversely, if the braking coefficient K is too small, it may not provide sufficient braking effect during faults outside the protection zone, thus affecting the protection's selectivity.

[0119] As can be seen from the above, in order to effectively improve the adaptability of differential protection, Embodiment 1 of the present invention aims to provide an adaptive adjustment ratio braking coefficient equation that can adaptively adjust the braking coefficient K according to different network topologies, so as to realize differential protection of multi-terminal lines.

[0120] Specifically, the multi-terminal differential protection method with adaptive adjustment ratio braking coefficient includes:

[0121] Step 1: The communication channel connects all endpoints of the line. The system monitors the status of the communication channel. By checking the enabled / disabled status of the communication channel, the system can identify which endpoints are normally connected to the main protection device. This step is achieved by monitoring the status of the channel switch. Only when the channel switch is enabled is the corresponding endpoint counted as an active endpoint. Based on this, in addition to the communication channel status, the protection system also uses electrical quantity auxiliary criteria to further confirm the actual operating status of the endpoints. This includes current, voltage, and other relevant electrical parameters, which can be used to detect whether the endpoints are truly participating in multi-terminal operation.

[0122] By combining the communication channel's on / off status and electrical quantity auxiliary criteria, the protection system can comprehensively judge and determine the actual number n of operating terminals on multi-terminal lines. This process is dynamic and can be updated in real time as system conditions change. For example, in the event of system reconfiguration or terminal faults, the protection system can quickly adapt to the new situation, recalculate the actual number of operating terminals, and adjust the parameters and operating logic of the differential protection accordingly.

[0123] Through this precise mechanism for obtaining the actual number of operating terminals n, the multi-terminal differential protection system can ensure reliability and selectivity under various operating conditions, effectively protect the stable operation of the power system, and prevent protection malfunctions or missed actions caused by misjudgment of terminal status.

[0124] Step 2: Based on the actual number of operating terminals n obtained in Step 1, construct a ratio braking coefficient value equation with inverse proportional characteristics and dynamic variability as an additional parameter to realize adaptive adjustment of the braking coefficient under different network topologies and improve the adaptability of differential protection.

[0125] Step 3: Obtain the adaptive allocation ratio braking coefficient equation based on the variable ratio braking coefficient value equation, including:

[0126] Step 3.1: Based on the actual number of operating terminals n obtained in Step 1, construct the equation for the variable ratio braking coefficient with inverse bit properties using it as an additional parameter:

[0127]

[0128] Where K(n) is the ratio braking coefficient, and a, b and c are adjustment coefficients. By adjusting the values ​​of a, b and c, the dynamic adjustment curve of the ratio braking coefficient after a fault can be obtained.

[0129] Based on simulation and experimental verification, we can set a = 1.2, b = -7, and c = 1, and substitute these values ​​into K(n) to obtain the equation for the variable ratio braking coefficient:

[0130]

[0131] The braking coefficient values ​​at different terminal numbers are shown in Table 1 below, and the corresponding braking coefficient curves are as follows: Figure 5 As shown;

[0132] End number n 2 3 4 5 6 7 ＞7 Braking coefficient k 0.74 0.55 0.43 0.34 0.27 0.22 0.2

[0133] Table 1

[0134] Step 3.2: Using the inverse braking coefficient equation, adjust the value of the ratio braking coefficient with time as the variable:

[0135]

[0136] Where K(t) is the ratio braking coefficient, K1 is the IEC constant (value 0.22), K2 is the adjustment coefficient, K3 is the starting threshold of K(t), t is time (ms), L is the IEC constant (value 0), and a is the IEC constant (value 0.03). Therefore, the formula for the ratio braking coefficient can be simplified as follows:

[0137]

[0138] By adjusting the values ​​of K2 and K3, the dynamic adjustment curve of the ratio braking coefficient after a fault can be obtained.

[0139] Based on simulation and experimental verification, typical values ​​can be set as shown in Table 2 below, and the corresponding curves for K(t) are as follows. Figure 2 , 3 As shown in Figure 4.

[0140] 2-3 terminal operation mode 4-6 terminal operation mode Operating mode with 7 or more terminals <![CDATA[K2]]> 0.3 0.165 0.11 <![CDATA[K3]]> 0.3 1.1 2.2 lower limit value 0.35 0.25 0.2

[0141] Table 2

[0142] Step 3.3, combining steps 3.1 and 3.2, yields the equation for the adaptive allocation ratio braking coefficient based on the number of terminals and time:

[0143]

[0144] Where K(t,n) is the ratio braking coefficient, K1 is the IEC constant (value 0.22), K2 is the adjustment coefficient, K3 is the starting threshold of K(t,n), t is time (ms), L is the IEC constant (value 0), and a is the IEC constant (value 0.03).

[0145]

[0146] Based on simulation and experimental verification, by setting the values ​​of K2=0.09 and K3=3, the dynamic adjustment curve of the ratio braking coefficient after a fault can be obtained. Figure 6 As shown.

[0147]

[0148] Therefore, to adapt to the characteristics of multi-terminal lines, the braking coefficient K should be inversely proportional to the number of system terminals. This means that as the number of terminals increases, the braking coefficient K should decrease accordingly to maintain the sensitivity and reliability of the differential protection. This adaptive braking coefficient adjustment mechanism ensures that the differential protection device can effectively respond to faults within the protection zone under different system configurations and operating conditions, while avoiding maloperation during faults outside the protection zone.

[0149] Example 2

[0150] The difference from Example 1 lies in step 3; the other steps are the same. Specifically, step 3 in this example is:

[0151] Step 3: Based on the variable ratio braking coefficient value equation, obtain the adaptive allocation ratio braking coefficient equation, including:

[0152] The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation:

[0153]

[0154] Calculate the error of the target braking coefficient and the rate of change of the error over time:

[0155] Δe(t,n)=K(n)-K(t-1,n);

[0156] d(Δe(t,n))=Δe(t,n)-Δe(t-1,n);

[0157] Based on the error of the target braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive engagement ratio braking coefficient equation is obtained:

[0158]

[0159] Where K(n) is the ratio braking coefficient, t is time, and K(t,n) is the ratio braking coefficient at time t based on the actual number of operating terminals n. p K I and K D These are the error coefficient, cumulative error coefficient, and rate of change error coefficient, respectively. Δe(t,n) is the error value relative to the target ratio braking coefficient K(n), and d(Δe(t,n)) is the rate of change of the error with time t. By adjusting K... p K I K D By taking the values ​​of the coefficient and the actual number of operating terminals n, the dynamic adjustment curve of the ratio braking coefficient after a fault can be obtained.

[0160] Based on simulation and experimental verification, taking an actual number of operational terminals of 4 as an example, we can set a = 1.2, b = -7, c = 1, and K... p =0.08, K I =0.01 and K D =0, and the dynamic adjustment curve of the ratio braking coefficient after the fault can be obtained, such as Figure 7 As shown.

[0161]

[0162] Therefore, to address transient faults in power systems, this embodiment also employs an intelligent delay strategy. In the initial stage of a fault, the device sets a relatively high threshold, allowing the system sufficient time to recover from the transient state. During this period, the protection continuously monitors the duration and amplitude of the fault current to determine if the fault is persistent. If it is a persistent fault, to quickly clear it, the device rapidly lowers the threshold of the braking current to K(n) using error coefficients, error accumulation coefficients, and error change rate coefficients, increasing the sensitivity to the fault until the operating conditions are met, thereby ensuring reliable operation when a real fault occurs. This strategy effectively avoids maloperation caused by system transients while ensuring effective detection of real faults, making it a key measure to ensure the safe and stable operation of the power system.

[0163] Those skilled in the art will recognize that the modules and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented using electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0164] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described apparatus and equipment can be referred to the corresponding process in the foregoing method implementation, and will not be repeated here.

[0165] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0166] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the objectives of the embodiments of the present invention, depending on actual needs.

[0167] In addition, the functional modules in the embodiments of the present invention can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0168] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the energy-saving signal transmission / reception methods of various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0169] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above-described features with (but not limited to) technical features with similar functions disclosed in this application.

[0170] It should be understood that the sequence number of each step in the invention and its embodiments does not absolutely imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A multi-terminal differential protection method for adaptively adjusting the braking coefficient ratio, characterized in that, include: Confirm the actual number of operational terminals of the multi-terminal line based on the communication channel's activation / deactivation status and electrical parameters; The actual number of operational terminals is used as an additional parameter to construct an equation for the value of the variable ratio braking coefficient with inverse bit properties. Based on the variable ratio braking coefficient value equation, an adaptive allocation ratio braking coefficient equation is obtained. According to the adaptive allocation ratio braking coefficient equation, the braking coefficient is adaptively adjusted under different network topologies. Based on the variable ratio braking coefficient value equation, the adaptive allocation ratio braking coefficient equation is obtained, including: The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation: ； in, Here, n is the ratio braking coefficient, a, b, and c are the adjustment coefficients, which are 1.2, -7, and 1, respectively. Calculate the error of the target ratio braking coefficient and the rate of change of the error over time: ； ； Based on the error of the target ratio braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive allocation ratio braking coefficient equation is obtained: ； in, The target ratio braking coefficient is given by t, where t is time. The ratio braking coefficient at time t is based on the actual number of terminals n in operation. , and These are the error coefficient, cumulative error coefficient, and rate of change of error coefficient, respectively. Braking coefficient relative to the target ratio The error value, Let be the rate of change of error with time t.

2. The multi-terminal differential protection method for adaptive adjustment ratio braking coefficient according to claim 1, characterized in that, Based on the communication channel's activation / deactivation status and electrical parameters, the actual number of multi-terminal lines in operation is confirmed as follows: The system monitors whether the channel pressure plate of the communication channel is engaged. When engaged, the endpoints of the corresponding lines are counted as operational endpoints. Then, the electrical parameter status of the line endpoints counted as operational endpoints is confirmed. If the electrical parameter status matches the actual operating status, the line endpoints counted as operational endpoints are confirmed as the actual operational endpoints.

3. The multi-terminal differential protection method for adaptively adjusting the braking coefficient according to claim 1, characterized in that, Based on the variable ratio braking coefficient value equation, the adaptive allocation ratio braking coefficient equation is obtained, including: The inverse braking coefficient equation is used to adjust the value of the ratio braking coefficient with time as the variable. Combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, an adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived.

4. The multi-terminal differential protection method for adaptively adjusting the braking coefficient according to claim 3, characterized in that, The method employs an anti-braking coefficient equation, adjusting the ratio braking coefficient with time as the variable as follows: ； in This is the ratio braking coefficient. For IEC constants, For adjustment coefficients, for The startup threshold is given by t, where t is time, L is an IEC constant, and f is an IEC constant.

5. The multi-terminal differential protection method for adaptively adjusting the braking coefficient according to claim 4, characterized in that, Combining the variable ratio braking coefficient value equation and the ratio braking coefficient value, the adaptive allocation ratio braking coefficient equation based on the number of terminals and time is derived as follows: ； in This is the ratio braking coefficient. For IEC constants, For adjustment coefficients, for The startup threshold is given by t, where t is time, n is the actual number of terminals in operation, L is an IEC constant, and f is an IEC constant.

6. A multi-terminal differential protection system with adaptive adjustment ratio braking coefficient, characterized in that, include: The actual number of operational terminals confirmation module confirms the actual number of multi-terminal lines in operation based on the communication channel's activation / deactivation status and electrical parameters. The variable ratio braking coefficient value equation construction module constructs a variable ratio braking coefficient value equation with inverse bit properties by using the actual number of operating terminals as an additional parameter. An adaptive allocation ratio braking coefficient equation construction module obtains an adaptive allocation ratio braking coefficient equation based on the variable ratio braking coefficient value equation, and realizes adaptive adjustment of the braking coefficient under different network topologies according to the adaptive allocation ratio braking coefficient equation. Based on the variable ratio braking coefficient value equation, the adaptive allocation ratio braking coefficient equation is obtained, including: The target ratio braking coefficient based on the actual number of operational terminals is obtained based on the variable ratio braking coefficient value equation: ； in, Here, n is the ratio braking coefficient, a, b, and c are the adjustment coefficients, which are 1.2, -7, and 1, respectively. Calculate the error of the target ratio braking coefficient and the rate of change of the error over time: ； ； Based on the error of the target ratio braking coefficient, the rate of change of the error over time, the error coefficient, the cumulative error coefficient, and the rate of change coefficient of the error, the adaptive allocation ratio braking coefficient equation is obtained: ； in, The target ratio braking coefficient is given by t, where t is time. The ratio braking coefficient at time t is based on the actual number of terminals n in operation. , and These are the error coefficient, cumulative error coefficient, and rate of change of error coefficient, respectively. Braking coefficient relative to the target ratio The error value, Let be the rate of change of error with time t.

7. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein the computer program, when executed by the processor, implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described in any one of claims 1-5.

8. A computer-readable storage medium, characterized in that, A computer program is stored on the computer-readable storage medium, which, when executed by a processor, implements the multi-terminal differential protection method for adaptive adjustment ratio braking coefficient as described in any one of claims 1-5.

Images