Self-powered protection device, quick protection method and computer equipment

Abstract

The invention belongs to the technical field of relay protection, and particularly relates to a self-powered protection device, a rapid protection method and computer equipment. When the operation time of the self-powered protection device is smaller than or equal to a preset time threshold value, the operation time interval of the operation time is determined, and an algorithm corresponding to the operation time interval is adopted to calculate power parameters of a line monitored by the device; and when the electric power parameter is greater than a preset parameter threshold value corresponding to the operation time interval, determining that a protection condition is satisfied. Wherein the larger the interval upper limit of the operation time interval is, the larger the preset parameter threshold value is; the calculation speed of the algorithm corresponding to the running time interval with the large interval upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the running time interval with the small interval upper limit. According to the invention, whether the protection condition is met or not can be found and judged under the condition that the operation time of the device is relatively short, and the quick action of the self-powered protection device is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of relay protection, and in particular relates to a self-powered protection device, a rapid protection method, and a computer device. Background Art

[0002] Self-powered protection devices are also called passive protection devices, which are mainly used for line protection in modern smart grids. They do not require external power supply, and mainly obtain energy from high-voltage cables through transformers, avoiding the failure of protection devices due to external power failure. Of course, self-powered protection devices can also be configured with other power supply modules, such as battery modules.

[0003] During a system fault, the input power supply (CT secondary current or PT secondary voltage) of the self-powered protection device will fluctuate violently. For the protection logic of the self-powered protection device, it is usually set to use the full-cycle Fourier algorithm to calculate the current amplitude of the monitoring line. If the calculated current amplitude exceeds the current protection setting, it is determined that the protection tripping condition of the self-powered protection device is met. Among them, the full-cycle Fourier algorithm is used to calculate the current amplitude of the monitoring line to ensure the accuracy of the calculation, but because the full-cycle Fourier algorithm requires more collected data to calculate, this method inevitably brings a problem, that is, the logic can usually only be protected after the self-powered protection device has been started for a period of time. However, the line may have a fault early, and the fault is serious. Waiting until the corresponding current amplitude is calculated using the full-cycle Fourier algorithm before taking action to isolate the fault, the fault may spread, making the reliability of the power grid low. Summary of the invention

[0004] The purpose of the present invention is to provide a self-powered protection device and a rapid protection method, and a computer device, so as to solve the problem that the fault propagation caused by the method in the prior art leads to low system reliability.

[0005] In order to solve the above technical problems, the present invention provides a self-powered protection device rapid protection method, the method comprising: Obtaining the operating time of the self-powered protection device, and determining the operating time interval in which the operating time is located when the operating time is less than or equal to a preset time threshold; The power parameter of the line monitored by the computing device is calculated using an algorithm corresponding to the operation time interval, and when the power parameter is greater than a preset parameter threshold corresponding to the operation time interval, it is determined that the protection condition is met; Among them, the preset parameter threshold is greater than the power parameter protection set value, the larger the upper limit of the operating time interval, the larger the preset parameter threshold; the calculation speed of the algorithm corresponding to the operating time interval with a large upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the operating time interval with a small upper limit, and the calculation speed of the algorithm used when the operating time is greater than the preset time threshold is greater than the calculation speed of the algorithm corresponding to the operating time interval.

[0006] Furthermore, the preset parameter threshold is the product of the power parameter protection constant and the setting coefficient; the setting coefficient is greater than 1, and the larger the upper limit of the operating time interval is, the larger the setting coefficient is.

[0007] Furthermore, there are two running time intervals.

[0008] Furthermore, the algorithms corresponding to the two running time intervals are both half-cycle Fourier algorithms.

[0009] Furthermore, the method also includes: when it is determined that the protection condition is met and the protection circuit of the device is open, the device is triggered to take a protection action; wherein, when the voltage of the energy storage capacitor in the device is greater than the allowable driving voltage of the coil driven by the device, the protection circuit is determined to be open.

[0010] Furthermore, when the voltage of the energy storage capacitor is continuously lower than the driving allowable voltage and the duration is greater than Tgj, a warning signal is issued; wherein Tgj represents the charging completion time for charging the energy storage capacitor through the line self-drawn electricity when a monitored line fault causes the line current to be greater than the minimum operating current of the device.

[0011] Furthermore, when the operating time is greater than a preset time threshold, a full-cycle Fourier algorithm is used to calculate the power parameters of the line monitored by the device, and when the power parameters are greater than the power parameter protection setting and the protection circuit is open, the protection action is triggered.

[0012] In order to solve the above technical problem, the present invention also provides a computer device, including a processor, wherein the processor executes a computer program to implement the steps of the self-powered protection device rapid protection method introduced above.

[0013] In order to solve the above technical problems, the present invention also provides a self-powered protection device, including a processor, wherein the processor executes a computer program to implement the steps of the self-powered protection device rapid protection method introduced above.

[0014] Furthermore, the self-powered protection device also includes an AC auxiliary power supply and a battery module, both of which are used to power the self-powered protection device.

[0015] The present invention is an improved invention creation, and has the following beneficial effects: the present invention sets a preset time threshold, and when the running time of the device is less than or equal to the preset time threshold, an algorithm with a faster calculation speed than the algorithm used when the running time is greater than the preset time threshold is used to calculate the power parameters, and accordingly, the threshold used to determine whether the protection conditions are met is also set larger than the power parameter protection constant, with the intention that when the running time of the self-powered protection device is relatively short, abnormal conditions can be quickly discovered and whether the protection conditions are met, thereby improving the reliability of fault detection, avoiding the spread of faults, and improving system reliability. Specifically, the present invention divides the operating time into intervals. The shorter the operating time, the larger the corresponding preset parameter threshold is set, and a suitable and fast algorithm is selected according to the operating time interval. However, it is required that the calculation speed of the algorithm corresponding to the operating time interval with a large interval upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the operating time interval with a small interval upper limit. When the operating time is short, a larger preset parameter threshold is selected to improve the tolerance of the selected algorithm to instantaneous data, accurately identify serious faults rather than interference, thereby realizing targeted selection of a suitable algorithm within the range of the operating time of the device being less than or equal to the preset time threshold, and judging whether the protection conditions are met according to the corresponding preset parameter threshold, thereby realizing rapid and reliable action of the self-powered protection device, especially faster action when a serious fault occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a structural diagram of the self-powered protection device of the present invention; Figure 2 It is a flow chart of the rapid protection method of the self-powered protection device of the present invention. DETAILED DESCRIPTION

[0017] When the operation time of the self-powered protection device is less than or equal to the preset time threshold, the present invention divides the operation time into several intervals, one operation time interval corresponds to an algorithm and a preset parameter threshold, and the preset parameter threshold is greater than the power parameter protection constant; the larger the interval upper limit of the operation time interval, the larger the preset parameter threshold; the calculation speed of the algorithm corresponding to the operation time interval with a large interval upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the operation time interval with a small interval upper limit, and the calculation speed of the algorithm used when the operation time is greater than the preset time threshold is greater than the calculation speed of the algorithm corresponding to the operation time interval. Based on this, the present invention first determines the operation time interval in which the operation time of the device is located, and then uses the algorithm corresponding to the operation time interval to calculate the power parameters of the line monitored by the device, and determines that the protection condition is met when the power parameter is greater than the preset parameter threshold corresponding to the operation time interval. Thereby, it is achieved that even when the operation time of the device is relatively short, abnormal conditions (serious abnormal conditions) can be discovered and whether the protection conditions are met, and the rapid action of the self-powered protection device is achieved.

[0018] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0019] Self-powered protection device embodiment: This embodiment provides a self-powered protection device, the structure of which is as follows: Figure 1 As shown, it is used to drive the low-power trip coil of the circuit breaker. The device includes a sampling and energy acquisition module for sampling the power parameters of the monitoring line and supplying power to the self-powered protection device, which is Figure 1 The CT current sampling / energy extraction module in the device can sample the line current on the one hand, and power the CT on the other hand. In addition, the device also includes an AC auxiliary power supply module and a battery module. These two power supply modules can also power the self-powered protection device. The AC auxiliary power supply module draws power from the grid through a transformer.

[0020] The device also includes a processor (CPU in this embodiment), a liquid crystal display module, a protection tripping circuit (also called a protection circuit) and an interactive interface; the interactive interface includes an IO interface, a communication interface and a USB interface. The protection tripping circuit can be powered by the above three power supply modules, or by the energy storage capacitor C. The protection tripping circuit is connected in series with an anti-reverse diode, a controllable switch S and an interface for connecting the tripping coil of the circuit breaker. When the CT current sampling / energy extraction module senses that the line current is too large, the controllable switch S is closed, the energy storage capacitor supplies power to the protection tripping circuit, and the circuit breaker is opened after the tripping coil is energized. The processor executes a computer program to implement a rapid protection method for a self-powered protection device of the present invention.

[0021] The entire protection device provides driving power for the tripping coil through the energy storage capacitor. Different input currents will affect the charging time of the energy storage capacitor, which means that the time required to charge the energy storage capacitor C varies under different working conditions. 1) When the circuit breaker is closed on an unloaded line, the line current is less than the minimum operating current Imin of the device, and the energy storage capacitor C is charged through the AC auxiliary power module, and the charging completion time is T1. 2) When the circuit breaker is closed on a faulty line, the line current is greater than the minimum operating current Imin of the device, and the energy storage capacitor C is charged through the CT current sampling / energy extraction module, and the charging completion time is T2. It should be noted that according to the functions of each module in the protection device, it can be divided into a core module and an auxiliary module. The core module is mainly used to realize the protection function, and the auxiliary module is mainly an interpersonal interaction module (such as a liquid crystal display module). Once the debugging is completed, this part of the module will not affect the protection function of the entire protection device, but when the input current of the device is small, the core module is opened first. The "minimum operating current Imin of the device" mentioned above is the minimum working current of the core module in the entire protection device.

[0022] Before the circuit breaker is closed, the self-powered protection device is in a power-off state; after the circuit breaker is closed, the device starts to power on, initialize and run, and the initialization completion time is T3. T2>T1>T3, 0.5*Tgp <T1-T3<Tgp,T2-T3> Tgp, Tgp is the power frequency period. When the system frequency is 50Hz, Tgp=20ms; when the system frequency is 60Hz, Tgp=16.7ms.

[0023] A quick protection method for a self-powered protection device of the present invention is introduced in detail below, involving the following two aspects.

[0024] 1. Opening of protection tripping circuit and early warning logic based on voltage monitoring of energy storage capacitors.

[0025] The voltage of the energy storage capacitor C is monitored in real time. When the voltage is greater than the allowable driving voltage of the driven coil (i.e., the tripping coil), the protection tripping circuit is opened; when the voltage is less than or equal to the allowable driving voltage and the duration reaches Tgj, an early warning signal is issued, and Tgj is greater than the charging completion time T2.

[0026] (ii) Adaptive rapid tripping condition determination of protection based on operating time control.

[0027] The key point here is to set a preset time threshold. When the operating time after the initialization of the self-powered protection device is greater than the preset time threshold, the power parameters of the monitored line are calculated according to the same algorithm as the prior art, and the threshold set for judging whether the protection tripping condition (also referred to as the protection condition) is met is the power parameter protection threshold; but when the operating time is relatively short, specifically less than the preset time threshold, an algorithm that is faster than the algorithm used when the time is greater than the preset time threshold is used to calculate the monitored power parameters, and the threshold set for judging whether the protection tripping condition is met is also set to be larger than the power parameter protection constant.

[0028] Specifically, the range of operation time less than or equal to the preset time threshold can be divided into several operation time intervals, and one operation time interval corresponds to an algorithm and a preset parameter threshold, and the preset parameter threshold is specifically set to the product of a setting coefficient and a power parameter protection constant, and the setting coefficient is a value greater than 1. The larger the upper limit of the operation time interval, the larger the corresponding setting coefficient, which also makes the corresponding preset parameter threshold larger; the calculation speed of the algorithm corresponding to the operation time interval with a large interval upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the operation time interval with a small interval upper limit, and the calculation speed of the algorithms corresponding to these operation time intervals is required to be less than the calculation speed of the algorithm adopted when the operation time is greater than the preset time threshold.

[0029] For example, the range of the running time less than or equal to the preset time threshold can be divided into two running time intervals, and the algorithms corresponding to these two running times are both the half-cycle Fourier algorithm. Of course, more running time intervals can also be divided, such as three running time intervals. The algorithms corresponding to these three running time intervals can all be the half-cycle Fourier algorithm, or one type of algorithm can be selected for the first two running time intervals with smaller values, and another relatively faster algorithm can be selected for the last running time interval with the largest value.

[0030] Taking the power parameter of the monitored line in this embodiment as the line current amplitude, the preset time threshold as Tgp, and dividing the range where the running time Trun of the device is less than or equal to Tgp into two intervals, namely (0.25*Tgp, 0.5*Tgp] and (0.5*Tgp, Tgp], and the set coefficients corresponding to these two intervals are Krel1 and Krel2 respectively, and Krel1 > Krel2, and the algorithms corresponding to these two intervals are both the half-cycle Fourier algorithm as an example to illustrate how to determine whether the protection tripping condition is satisfied. The specific process is as Figure 2 shown.

[0031] 1) When the running time Trun of the device satisfies 0.25*Tgp < Trun ≤ 0.5*Tgp, the software uses the half-cycle Fourier algorithm to calculate the line current amplitude Ibz, and if the calculated line current amplitude Ibz is greater than Krel1 times the current protection setting value Iset (Krel1*Iset), it is determined that the protection tripping condition is satisfied.

[0032] 2) When the running time Trun of the device satisfies 0.5*Tgp < Trun ≤ Tgp, the software uses the half-cycle Fourier algorithm to calculate the line current amplitude Ibz, and if the calculated line current amplitude Ibz is greater than Krel2 times the current protection setting value (Krel2*Iset), it is determined that the protection tripping condition is satisfied.

[0033] 3) When the running time Trun of the device satisfies Trun > Tgp, the software uses the full-cycle Fourier algorithm to calculate the line current amplitude Iqz, and if the calculated line current amplitude is greater than the current protection setting value (Iset), it is determined that the protection tripping condition is satisfied.

[0034] When it is detected that any of the above protection tripping conditions is satisfied and the protection tripping circuit is open, the protection tripping output is triggered to trip the circuit breaker.

[0035] It should be noted that in the initial stage of a power system fault, the fault current often contains significant non-periodic components. Compared with the full-cycle Fourier algorithm, the half-cycle Fourier algorithm has a larger error when used for calculations involving non-periodic components. Therefore, when selecting the half-cycle Fourier algorithm, it is necessary to multiply the current protection setting value by a reliability factor greater than 1 to improve the reliability of fault detection. In steps 1) and 2) above, the purpose of dividing the range of operating time Trun ≤ Tgp into two intervals is to enable faster operation in the event of a severe fault. When 0.25*Tgp < Trun ≤ 0.5*Tgp, the data required for the half-cycle Fourier algorithm is not full-window. To improve the tolerance of the algorithm to instantaneous disturbance data, a larger reliability factor is selected to distinguish between disturbances and severe faults.

[0036] In this embodiment, the preset time threshold is the power frequency period Tgp. This setting is because Tgp is the precise working boundary of the full-cycle Fourier algorithm. The full-cycle Fourier algorithm requires full-window data, and its result output accuracy is higher than that of the half-cycle Fourier algorithm. Selecting Tgp as the boundary, it is intended to select a more precise algorithm for system fault detection as early as possible under permitted conditions.

[0037] Currently, all algorithms in relay protection software design are divided into two categories: discrimination algorithms and measurement algorithms. Discrimination algorithms include sampling value discrimination algorithms and vector discrimination algorithms; the sampling value algorithm (such as the three-point algorithm) can achieve fast fault detection but cannot be used alone. The recording of fault quantity values still needs to be implemented by the measurement algorithm; the vector discrimination algorithm directly uses the output results of the measurement algorithm for discrimination. Commonly used measurement algorithms for low-voltage protection include the full-cycle Fourier algorithm, the full-cycle Fourier algorithm with difference, the half-cycle Fourier algorithm, the half-cycle Fourier algorithm with difference, etc. The difference algorithm is mostly used in scenarios where it is necessary to suppress the influence of non-periodic components, but the data window length has one more sampling point. In this embodiment, the relatively common full-cycle Fourier algorithm and half-cycle Fourier algorithm are used as examples. For other scenarios, the required relay protection software algorithms can be adaptively selected according to the actual situation. However, it should be noted that the corresponding preset time threshold needs to be selected according to the precise working boundary of the selected algorithm.

[0038] Embodiment of the fast protection method for a self-powered protection device: In an embodiment of the fast protection method for a self-powered protection device of the present invention, the application scenario, specific execution process, etc. of this method have been introduced in detail in the embodiment of the self-powered protection device, and will not be repeated in this embodiment.

[0039] Embodiment of computer equipment: A computer device embodiment of the present invention includes a memory, a processor, an internal bus and a computer program stored in the memory, and the processor and the memory communicate and exchange data with each other through the internal bus. The processor executes the computer program to implement the steps of a self-powered protection device rapid protection method introduced in the self-powered protection device embodiment of the present invention. Among them, the processor can be a processing device such as a microprocessor MCU, a programmable logic device FPGA, etc.; the memory can be various memories that use electrical energy to store information, such as RAM, ROM, etc., or it can be a memory using other methods.

[0040] In summary, the present invention can quickly detect abnormal conditions (serious abnormal conditions) and determine whether the protection conditions are met even when the self-powered protection device has a relatively short operating time, thereby achieving rapid and reliable operation of the self-powered protection device, avoiding the spread of faults, and improving system reliability.

[0041] Specific implementation methods are given above, but the present invention is not limited to the described implementation methods. The basic idea of ​​the present invention lies in the above basic scheme. For ordinary technicians in this field, it does not take creative work to design various deformed models, formulas, and parameters according to the teachings of the present invention. Changes, modifications, substitutions, and variations of the implementation methods without departing from the principles and spirit of the present invention still fall within the scope of protection of the present invention.

Claims

1. A rapid protection method for a self-powered protection device, characterized in that: The method includes: Obtaining the operating time of the self-powered protection device, and determining the operating time interval in which the operating time is located when the operating time is less than or equal to a preset time threshold; The power parameter of the line monitored by the computing device is calculated using an algorithm corresponding to the operation time interval, and when the power parameter is greater than a preset parameter threshold corresponding to the operation time interval, it is determined that the protection condition is met; Among them, the preset parameter threshold is greater than the power parameter protection set value, the larger the upper limit of the operating time interval, the larger the preset parameter threshold; the calculation speed of the algorithm corresponding to the operating time interval with a large upper limit is greater than or equal to the calculation speed of the algorithm corresponding to the operating time interval with a small upper limit, and the calculation speed of the algorithm used when the operating time is greater than the preset time threshold is greater than the calculation speed of the algorithm corresponding to the operating time interval.

2. The rapid protection method for a self-powered protection device according to claim 1, characterized in that: The preset parameter threshold is the product of the power parameter protection constant and the setting coefficient; the setting coefficient is greater than 1, and the larger the upper limit of the operating time interval is, the larger the setting coefficient is.

3. The rapid protection method for a self-powered protection device according to claim 1, characterized in that: There are two running time intervals.

4. The rapid protection method for a self-powered protection device according to claim 3, characterized in that: The algorithms corresponding to the two running time intervals are both half-cycle Fourier algorithms.

5. The rapid protection method for a self-powered protection device according to claim 1, characterized in that: The method also includes: when it is determined that the protection condition is met and the protection circuit of the device is open, the device is triggered to take a protection action; wherein, when the voltage of the energy storage capacitor in the device is greater than the driving allowable voltage of the coil driven by the device, it is determined that the protection circuit is open.

6. The rapid protection method for a self-powered protection device according to claim 5, characterized in that: When the voltage of the energy storage capacitor is continuously lower than the driving allowable voltage and the duration is greater than Tgj, a warning signal is issued; wherein Tgj represents the charging completion time of the energy storage capacitor through the line self-drawn electricity when the monitored line fault causes the line current to be greater than the minimum operating current of the device.

7. The rapid protection method for a self-powered protection device according to any one of claims 1 to 6, characterized in that: When the running time is greater than the preset time threshold, the full-cycle Fourier algorithm is used to calculate the power parameters of the line monitored by the device. When the power parameters are greater than the power parameter protection set value and the protection circuit is open, the protection action is triggered.

8. A computer device comprising a processor, characterized in that: The processor executes a computer program to implement the steps of the method according to any one of claims 1 to 7.

9. A self-powered protection device, comprising a processor, characterized in that: The processor executes a computer program to implement the steps of the method according to any one of claims 1 to 7.

10. The self-powered protection device according to claim 9, characterized in that: The self-powered protection device also includes an AC auxiliary power supply and a battery module, both of which are used to supply power to the self-powered protection device.

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