High voltage overcurrent protection delay calculation method

Abstract

A method for calculating the delay of high-voltage overcurrent protection relates to the technical field of power systems. The method first selects voltage and current data collected by a target device within the past month as sample data, then filters out two suitable sampling points from the sample data as target points. The target device's operating current and voltage values ​​are calculated using the filtered target points and the data between the target points. The target device's operating current and voltage values ​​are then dynamically adjusted based on the target device's operating current and voltage values ​​and the current current and voltage values. The method provided by the present invention is used in an overcurrent protection mechanism for high-voltage electrical equipment in a power system.

Description

Technical Field

[0001] The present invention relates to the technology of power system, in particular to the technology of a high-voltage overcurrent protection delay calculation method. Background Art

[0002] High-voltage electrical equipment is installed in the high-voltage power supply circuit of the power system (high voltage refers to a voltage greater than or equal to 10kV). Overcurrent protection is a measure to protect the safety of high-voltage electrical equipment.

[0003] The overcurrent protection mechanism of high-voltage electrical equipment will implement quick-break protection (quickly cut off the circuit) when it detects a large current. However, when the overcurrent protection mechanism detects a slightly higher current, in order to avoid the instantaneous current disturbance triggering the overcurrent protection mechanism (for example, the instantaneous current when high-voltage electrical equipment starts will be significantly higher than the rated current), the overcurrent protection mechanism will delay for a certain period of time. If the overcurrent condition still exists after the delay, the overcurrent protection action will be taken.

[0004] The current value of high-voltage electrical equipment will change under different operating conditions. However, in the existing overcurrent protection mechanism of high-voltage electrical equipment, the overcurrent protection delay time is a fixed value (for example, a delay of 1 millisecond). The protection delay time cannot be dynamically adjusted according to the operating conditions of the equipment, which is prone to false operation due to incorrect fault judgment. Summary of the Invention

[0005] In view of the defects existing in the above-mentioned prior art, the technical problem to be solved by the present invention is to provide a high-voltage overcurrent protection delay calculation method that can dynamically adjust the overcurrent protection delay duration according to the real-time operating conditions of the equipment, thereby avoiding the malfunction of the overcurrent protection mechanism.

[0006] In order to solve the above technical problems, the present invention provides a method for calculating the high-voltage overcurrent protection delay, which is characterized by the following specific steps:

[0007] 1) The high-voltage electrical equipment in the power system whose high-voltage overcurrent protection delay is to be calculated is set as the target equipment, and the voltage and current data collected by the target equipment in the last month are selected as sample data. The data sampling points in the sample data are arranged in order from near to far according to the collection time sequence;

[0008] 2) Select two sampling points from the sample data as target points. The rule for selecting target points is: for any two sampling points K and J in the sample data, if the two sampling points can simultaneously meet conditions 1, 2, and 3, then the two sampling points are defined as target points;

[0009] Condition 1:

[0010] The two sampling points are K and J in order from near to far according to the collection time sequence, where sampling point K is the kth sampling point in the sample data, sampling point J is the jth sampling point in the sample data, and the time interval between sampling points K and J is at least 12 hours;

[0011] Condition 2:

[0012] And (U(k)≤0.95×Un||U(k)≥1.05×Un), and (U(j-1)≤0.95×Un||U(j-1)≥1.05×Un);

[0013] Where, It means that the voltage value of each sampling point in the interval [j, k) is greater than 0.95×Un and less than 1.05×Un. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. Un is the rated voltage of the bus where the target device is located, U(k) is the voltage value of sampling point K, and U(j-1) is the voltage value of the j-1th sampling point in the sample data.

[0014] Condition 3:

[0015] And (I(k)≤In / 20||I(k)≥1.2×In), and (I(j-1)≤In / 20||I(j-1)≥1.2×In);

[0016] Where, It means that the current collected value of each sampling point in the interval [j, k) is greater than In / 20 and less than 1.2×In. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. In is the rated current value of the target device, I(k) is the current collected value of sampling point K, and I(j-1) is the current collected value of the j-1th sampling point in the sample data.

[0017] 3) Calculate the operating current and voltage of the target device using the following formula:

[0018]

[0019]

[0020] Where Is is the operating current value of the target device, Us is the operating voltage value of the target device, I(i) is the current acquisition value of the i-th sampling point in the sample data, and U(i) is the voltage acquisition value of the i-th sampling point in the sample data;

[0021] 4) Set the protection action delay time Tt of the target equipment. The initial value of Tt is usually determined according to the load type of the electrical equipment, and its typical value is 1000ms;

[0022] 5) Define the current data sampling time of the target device as time t. If I(t)>Is, go to step 6), otherwise go to step 7); where I(t) is the current data collected by the target device at time t;

[0023] 6) Calculate the protection delay coefficient Cos at time t, and update the value of the protection action delay time Tt of the target device to Tt / Cos. The calculation formula of the protection delay coefficient Cos is:

[0024] If 0.95×Un<U(k)<1.05×Un, then: Cos=(I(t) / Is) 0.02

[0025] If U(k)≤0.95×Un||U(k)≥1.05×Un, then: Cos=(I(t) / Is+U(t) / Us) 0.02

[0026] Where, I(t) is the current value collected by the target device at time t, and U(t) is the voltage value collected by the target device at time t;

[0027] 7) Wait for the target device to reach the next current data sampling time, and then return to step 5).

[0028] The high-voltage overcurrent protection delay calculation method provided by the present invention calculates the operating current value and operating voltage value of the high-voltage electrical equipment based on historical collected data, and then calculates the overcurrent protection delay duration based on the real-time current value, real-time voltage value, operating current value, and operating voltage value of the high-voltage electrical equipment. The overcurrent protection delay duration can be dynamically adjusted according to the real-time operating conditions of the equipment, thereby avoiding malfunction of the overcurrent protection mechanism. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments, but this embodiment is not intended to limit the present invention. All similar structures and similar variations of the present invention should be included in the scope of protection of the present invention. The semicolons in the present invention represent the relationship of and, and the English letters in the present invention are case-sensitive.

[0030] An embodiment of the present invention provides a method for calculating a high-voltage overcurrent protection delay, characterized in that the specific steps are as follows:

[0031] 1) The high-voltage electrical equipment in the power system whose high-voltage overcurrent protection delay is to be calculated is set as the target equipment. The voltage and current data collected by the target equipment in the last month are selected as sample data. The data sampling points in the sample data (voltage and current data are collected once at each sampling point) are arranged in order from near to far according to the collection time sequence;

[0032] 2) Select two sampling points from the sample data as target points. The rule for selecting target points is: for any two sampling points K and J in the sample data, if the two sampling points can simultaneously meet conditions 1, 2, and 3, then the two sampling points are defined as target points;

[0033] Condition 1:

[0034] The two sampling points are K and J in order from near to far according to the collection time sequence, where sampling point K is the kth sampling point in the sample data, sampling point J is the jth sampling point in the sample data, and the time interval between sampling points K and J is at least 12 hours;

[0035] Condition 2:

[0036] And (U(k)≤0.95×Un||U(k)≥1.05×Un), and (U(j-1)≤0.95×Un||U(j-1)≥1.05×Un);

[0037] Where, It means that the voltage value of each sampling point in the interval [j, k) is greater than 0.95×Un and less than 1.05×Un. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. Un is the rated voltage of the bus where the target device is located, U(k) is the voltage value of sampling point K, and U(j-1) is the voltage value of the j-1th sampling point in the sample data.

[0038] Condition 3:

[0039] And (I(k)≤In / 20||I(k)≥1.2×In), and (I(j-1)≤In / 20||I(j-1)≥1.2×In);

[0040] Where, It means that the current collected value of each sampling point in the interval [j, k) is greater than In / 20 and less than 1.2×In. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. In is the rated current value of the target device, I(k) is the current collected value of sampling point K, and I(j-1) is the current collected value of the j-1th sampling point in the sample data.

[0041] 3) Calculate the operating current and voltage of the target device using the following formula:

[0042]

[0043]

[0044] Where Is is the operating current value of the target device, Us is the operating voltage value of the target device, I(i) is the current acquisition value of the i-th sampling point in the sample data, and U(i) is the voltage acquisition value of the i-th sampling point in the sample data;

[0045] 4) Set the protection action delay time Tt of the target equipment. The initial value of Tt is usually determined according to the load type of the electrical equipment, and its typical value is 1000ms;

[0046] 5) Define the current data sampling time of the target device as time t. If I(t)>Is, go to step 6), otherwise go to step 7); where I(t) is the current data collected by the target device at time t;

[0047] 6) Calculate the protection delay coefficient Cos at time t, and update the value of the protection action delay time Tt of the target device to Tt / Cos. The calculation formula of the protection delay coefficient Cos is:

[0048] If 0.95×Un<U(k)<1.05×Un, then: Cos=(I(t) / Is) 0.02

[0049] If U(k)≤0.95×Un||U(k)≥1.05×Un, then: Cos=(I(t) / Is+U(t) / Us) 0.02

[0050] Where I(t) is the current value collected by the target device at time t, and I(t) is the voltage value collected by the target device at time t;

[0051] 7) Wait for the target device to reach the next current data sampling time, and then return to step 5).

[0052] The embodiment of the present invention can dynamically adjust the overcurrent protection delay time according to the real-time working conditions of the equipment, thereby avoiding the malfunction of the overcurrent protection mechanism, automatically avoiding the action range when the equipment is started, and will not affect the fault judgment in the case of a short circuit.

Claims

1. A method for calculating the delay of high-voltage overcurrent protection, characterized in that: The specific steps are as follows: 1) The high-voltage electrical equipment in the power system whose high-voltage overcurrent protection delay is to be calculated is set as the target equipment, and the voltage and current data collected by the target equipment in the last month are selected as sample data. The data sampling points in the sample data are arranged in order from near to far according to the collection time sequence; 2) Select two sampling points from the sample data as target points. The rule for selecting target points is: for any two sampling points K and J in the sample data, if the two sampling points can simultaneously meet conditions 1, 2, and 3, then the two sampling points are defined as target points; Condition 1: The two sampling points are K and J in order from near to far according to the collection time sequence, where sampling point K is the kth sampling point in the sample data, sampling point J is the jth sampling point in the sample data, and the time interval between sampling points K and J is at least 12 hours; Condition 2: and (U(k) ≤ 0.95×Un || U(k) ≥ 1.05×Un), and (U(j - 1) ≤ 0.95×Un || U(j - 1) ≥ 1.05×Un); Where, It means that the voltage value of each sampling point in the interval [j, k) is greater than 0.95×Un and less than 1.05×Un. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. Un is the rated voltage of the bus where the target device is located, U(k) is the voltage value of sampling point K, and U(j-1) is the voltage value of the j-1th sampling point in the sample data. Condition 3: And (I(k)≤In / 20||I(k)≥1.2×In), and (I(j-1)≤In / 20||I(j-1)≥1.2×In); Where, It means that the current collected value of each sampling point in the interval [j, k) is greater than In / 20 and less than 1.2×In. The interval [j, k) includes sampling point J and the sampling points between sampling points J and K. In is the rated current value of the target device, I(k) is the current collected value of sampling point K, and I(j-1) is the current collected value of the j-1th sampling point in the sample data. 3) Calculate the operating current and voltage of the target device using the following formula: Where Is is the operating current value of the target device, Us is the operating voltage value of the target device, I(i) is the current acquisition value of the i-th sampling point in the sample data, and U(i) is the voltage acquisition value of the i-th sampling point in the sample data; 4) Set the protection action delay time Tt of the target equipment. The initial value of Tt is usually determined according to the load type of the electrical equipment, and its typical value is 1000ms; 5) Define the current data sampling time of the target device as time t. If I(t)>Is, go to step 6), otherwise go to step 7); where I(t) is the current data collected by the target device at time t; 6) Calculate the protection delay coefficient Cos at time t, and update the value of the protection action delay time Tt of the target device to Tt / Cos. The calculation formula of the protection delay coefficient Cos is: If 0.95×Un<U(k)<1.05×Un, then: Cos=(I(t) / Is) 0.02 If U(k) ≤ 0.95×Un || U(k) ≥ 1.05×Un, then: Cos = (I(t) / Is + U(t) / Us) 0.02 Where, I(t) is the current value collected by the target device at time t, and U(t) is the voltage value collected by the target device at time t; 7) Wait for the target device to reach the next current data sampling time, and then return to step 5).

Images