CN103728538A - Ground fault line selecting method for small current grounding system - Google Patents

Abstract

Translated fromChinese

本发明提供一种小电流接地系统的接地故障选线方法，该方法包括：零序电压互感器和零序电流互感器分别获取小电流接地系统故障时的零序电压信号和零序电流信号；二次电压变送器和二次电流变送器分别将电压信号和电流信号转换为故障线路识别的测量信号；将测量信号经可编程运算放大器处理后发送至FPGA模块；FPGA模块控制AD采样模块进行高速同步采样；FPGA模块采样获取的采样码流数据以DMA的方式送到嵌入式处理器中；嵌入式处理器处理所述采样码流数据；接地故障选线检测。该方法利用FPGA控制AD采样芯片实现高速采样，实现嵌入式处理器与FPGA模块之间的DMA通信，提升数据吞吐能力，使嵌入式处理器有更多的资源用于多种故障选线算法判断逻辑的综合应用。

The invention provides a grounding fault line selection method for a small current grounding system, the method comprising: a zero-sequence voltage transformer and a zero-sequence current transformer respectively obtain a zero-sequence voltage signal and a zero-sequence current signal when the small-current grounding system fails; The secondary voltage transmitter and the secondary current transmitter convert the voltage signal and current signal into measurement signals for fault line identification; the measurement signals are processed by a programmable operational amplifier and sent to the FPGA module; the FPGA module controls the AD sampling module Perform high-speed synchronous sampling; the sampling code stream data acquired by FPGA module sampling is sent to the embedded processor in the form of DMA; the embedded processor processes the sampling code stream data; ground fault line selection detection. This method uses FPGA to control the AD sampling chip to achieve high-speed sampling, realizes DMA communication between the embedded processor and the FPGA module, improves data throughput, and enables the embedded processor to have more resources for multiple fault line selection algorithm judgments Comprehensive application of logic.

Description

Translated fromChinese

一种小电流接地系统的接地故障选线方法A Ground Fault Line Selection Method for Small Current Grounding System

技术领域technical field

本发明涉及一种电力系统领域的方法，具体涉及一种小电流接地系统的接地故障选线方法。The invention relates to a method in the field of electric power systems, in particular to a ground fault line selection method for a small current grounding system.

背景技术Background technique

电力系统按中性点运行方式分为两种：中性点有效接地系统和中性点非有效接地系统。中性点直接接地或经过低值阻抗接地的系统称为中性点有效接地系统或大电流接地系统；中性点不接地、经高值阻抗接地或经消弧线圈（消弧电抗器）接地（谐振接地），称为中性点非有效接地系统或小电流接地系统。The power system is divided into two types according to the neutral point operation mode: the neutral point effective grounding system and the neutral point non-effective grounding system. The neutral point is directly grounded or grounded through a low-value impedance system, which is called a neutral point effective grounding system or a high-current grounding system; the neutral point is not grounded, grounded through a high-value impedance, or grounded through an arc-suppression coil (arc-suppression reactor) (Resonant grounding), known as neutral point non-effective grounding system or small current grounding system.

在6～66kV配电网中，广泛采用的是小电流接地系统。配电网采用小电流接地系统的优点为：在发生单相接地故障时，由于中性点非有效接地，故障点不会产生大的短路电流，而且相与相之间的线电压仍保持对称，不影响对负荷的供电，因此允许系统短时间带故障运行，这对于减少用户停电时间，提高供电可靠性是非常有意义的。但是，相应的问题也随之而来，由于小电流接地电网单相接地时故障电流非常小，加之配电网结构复杂，运行方式多变，使配电网的故障选线受到很多的限制，给故障选线造成困难。采用常规继电保护装置根本无法准确检出故障线路，导致长期以来小电流单相接地故障选线问题成为一个技术难题。目前也提出了一些小电流接地系统的接地故障线路方法，但这些方法总体存在一定的不足之处，主要是故障特征提取能力差，选线方法单一等。In the 6 ~ 66kV distribution network, the small current grounding system is widely used. The advantage of using a small current grounding system in the distribution network is that when a single-phase ground fault occurs, the fault point will not generate a large short-circuit current because the neutral point is not effectively grounded, and the phase-to-phase line voltage remains symmetrical. , does not affect the power supply to the load, so the system is allowed to run with faults for a short time, which is very meaningful for reducing the power outage time of users and improving the reliability of power supply. However, the corresponding problems also follow. Because the fault current is very small when the single-phase grounding of the small current grounding grid is grounded, and the structure of the distribution network is complex and the operation mode is changeable, the fault line selection of the distribution network is subject to many restrictions. Difficulty in fault line selection. Conventional relay protection devices cannot accurately detect the fault line at all, which has led to the problem of line selection for small current single-phase ground faults becoming a technical problem for a long time. At present, some ground fault line methods for small current grounding systems have also been proposed, but these methods generally have certain deficiencies, mainly because of poor fault feature extraction capabilities and single line selection methods.

因此，需要提供一种速度更快、效率更高、判断更准确的故障选线方法。Therefore, it is necessary to provide a fault line selection method with faster speed, higher efficiency and more accurate judgment.

发明内容Contents of the invention

为了克服上述现有技术的缺陷，本发明提供一种小电流接地系统的接地故障选线方法，该方法具有能够自适应的根据故障特征的大小对程控运算放大器进行动态设置，利用FPGA控制AD采样芯片实现高速采样，同时实现嵌入式处理器与FPGA模块之间的DMA通信，提升数据吞吐能力，从而使嵌入式处理器能够有更多的资源用于多种故障选线算法判断逻辑的综合应用。In order to overcome the defects of the above-mentioned prior art, the present invention provides a grounding fault line selection method for a small current grounding system. The method has the ability to dynamically set the program-controlled operational amplifier according to the size of the fault feature, and uses FPGA to control AD sampling. The chip realizes high-speed sampling, and at the same time realizes DMA communication between the embedded processor and the FPGA module, improving data throughput, so that the embedded processor can have more resources for the comprehensive application of various fault line selection algorithm judgment logics .

为了实现上述发明目的，本发明采取如下技术方案：In order to realize the above-mentioned purpose of the invention, the present invention takes the following technical solutions:

一种小电流接地系统的接地故障选线方法，其改进之处在于：所述方法包括以下步骤：A ground fault line selection method for a small current grounding system, the improvement of which is that the method includes the following steps:

I、零序电压互感器和零序电流互感器分别获取小电流接地系统故障时的零序电压信号和零序电流信号；1, the zero-sequence voltage transformer and the zero-sequence current transformer obtain the zero-sequence voltage signal and the zero-sequence current signal when the small current grounding system fails respectively;

II、二次电压变送器和二次电流变送器分别将所述电压信号和电流信号转换为故障线路识别的测量信号；II. The secondary voltage transmitter and the secondary current transmitter respectively convert the voltage signal and the current signal into measurement signals for fault line identification;

III、将所述测量信号经可编程运算放大器处理后发送至FPGA模块；III, the measurement signal is sent to the FPGA module after being processed by a programmable operational amplifier;

IV、FPGA模块控制AD采样模块进行高速同步采样；IV. The FPGA module controls the AD sampling module to perform high-speed synchronous sampling;

V、所述FPGA模块采样获取的采样码流数据以DMA的方式送到嵌入式处理器中；V, the sampling code stream data that described FPGA module sampling obtains sends in the embedded processor with the mode of DMA;

VI、所述嵌入式处理器处理所述采样码流数据；VI, the embedded processor processes the sampling stream data;

VII、接地故障选线检测。VII. Ground fault line selection detection.

进一步的，所述步骤III中，所述可编程运算放大器的放大倍数由进行故障识别判断的嵌入式处理器根据接地故障时零序故障电流的强弱确定。Further, in the step III, the amplification factor of the programmable operational amplifier is determined by the embedded processor for fault identification and judgment according to the strength of the zero-sequence fault current during the ground fault.

进一步的，所述步骤IV中，所述FPGA模块控制AD采样模块进行高速同步采样，所述FPGA模块实现高速AD采样，采样速率为25600每秒。Further, in the step IV, the FPGA module controls the AD sampling module to perform high-speed synchronous sampling, and the FPGA module realizes high-speed AD sampling with a sampling rate of 25600 per second.

进一步的，所述步骤VI中，所述嵌入式处理器对所述采样码流数据进行有效值和相位信息计算，包括零序电压的基波幅值信息、基波相位信息、五次谐波幅值信息、五次谐波相位信息和零序电压的频率的计算。Further, in the step VI, the embedded processor calculates the effective value and phase information of the sampled code stream data, including fundamental wave amplitude information, fundamental wave phase information, fifth harmonic Calculation of magnitude information, fifth harmonic phase information and frequency of zero sequence voltage.

进一步的，所述步骤VII包括以下步骤：Further, said step VII includes the following steps:

S701、根据所述步骤VI的数据及缓冲数据进行零序电压突变量检测，当零序电压突变量启动且零序电压越限则进入接地故障选线逻辑；S701. Perform zero-sequence voltage mutation detection according to the data and buffer data in step VI. When the zero-sequence voltage mutation starts and the zero-sequence voltage exceeds the limit, enter the ground fault line selection logic;

S702、当零序电压突变量启动，获取所有线路的暂态能量并排序，对前三大暂态能量的线路进行暂态强度检测；S702. When the zero-sequence voltage mutation is started, acquire and sort the transient energies of all lines, and perform transient intensity detection on the lines with the top three transient energies;

当暂态强度大于2时，则运用暂态极性方法分析表征线路接地故障特征的零序电流，确定故障线路；When the transient intensity is greater than 2, use the transient polarity method to analyze the zero-sequence current that characterizes the ground fault characteristics of the line to determine the fault line;

当暂态强度小于2时，分析零序电压的相位，当零序电压在过零点附近时，判断小电流系统是否存在消弧线圈接地，存在则确定衰减直流分量，在前三明显的暂态故障特征线路中，衰减直流分量大于另两条线路衰减直流分量之和的线路为故障线路，进入步骤S704；否则进入步骤S703；When the transient intensity is less than 2, analyze the phase of the zero-sequence voltage. When the zero-sequence voltage is near the zero-crossing point, judge whether there is an arc suppression coil grounding in the small current system. If it exists, determine the attenuated DC component. In the first three obvious transients Among the fault characteristic lines, the line whose attenuated DC component is greater than the sum of the attenuated DC components of the other two lines is a faulty line, and enters step S704; otherwise, enters step S703;

S703、当暂态强度小于2时，小电流接地系统不存在消弧线圈接地，则确定前三大每周波零序电流幅值的线路，对比线路的相位和零序电压的相位；S703. When the transient intensity is less than 2, and there is no arc suppressing coil grounding in the small current grounding system, determine the first three circuits with zero-sequence current amplitudes per cycle, and compare the phases of the lines with the phases of the zero-sequence voltage;

若某线路的相位与零序电压相位相反，则认为故障线路；获取其零序电流码值的放大倍数，保证下次接地故障时，故障特征以所述放大倍数放大；进入步骤S705；If the phase of a certain line is opposite to the phase of the zero-sequence voltage, it is considered a faulty line; obtain the magnification of its zero-sequence current code value to ensure that the fault feature is amplified by the magnification when the next ground fault occurs; enter step S705;

S704、连续3次进行步骤S702中的选线判断，若结果一致，则认为选线正确；S704, carry out the line selection judgment in step S702 for 3 consecutive times, if the results are consistent, then consider that the line selection is correct;

否则获取小电流接地系统存在消弧线圈接地时零序电流中五次谐波电流最大的线路，判断该线路的五次谐波电流与基波电流的比值是否大于8%，大于则比对五次谐波电流前三大的线路的相位与零序电压的五次谐波相位，认为五次谐波电流和零序电压的五次谐波相位相反的线路为故障线路；进入步骤S703；Otherwise, obtain the line with the largest fifth harmonic current in the zero sequence current when the arc suppressing coil is grounded in the small current grounding system, and judge whether the ratio of the fifth harmonic current to the fundamental current of the line is greater than 8%, and if it is greater, compare the five The phases of the first three major lines of the sub-harmonic current and the fifth harmonic phase of the zero-sequence voltage are considered to be faulty lines with opposite phases of the fifth harmonic current and the fifth harmonic phase of the zero-sequence voltage; enter step S703;

S705、连续3次进行步骤S703中五次谐波选线判断，若结果一致，则认为选线正确；S705, carry out the line selection judgment of the fifth harmonic in step S703 for 3 consecutive times, if the results are consistent, it is considered that the line selection is correct;

否则获取小电流接地系统消弧线圈接地时，利用能量法对所述步骤S702中五次谐波电流前三大的线路进行选线，认为有功功率大于另两条线路之和的线路为故障线路；Otherwise, when the arc suppressing coil of the small current grounding system is grounded, use the energy method to select the lines with the top three lines of the fifth harmonic current in the step S702, and consider the line whose active power is greater than the sum of the other two lines to be the faulty line ;

S706、若上述步骤S702、S703、S7604和S705选线失败，则认为母线接地故障。S706. If the line selection in the above steps S702, S703, S7604 and S705 fails, it is considered that the busbar is grounded.

与现有技术相比，本发明的有益效果在于：Compared with prior art, the beneficial effect of the present invention is:

1、本发明的方法能够根据电力系统的实际运行情况，自适应的根据上次发生接地故障时零序电流的大小调制程控运放的放大倍数，从而能够提升微弱的故障零序电流的提取能力，提升故障选线的准确度。1. The method of the present invention can adaptively modulate the magnification of the program-controlled operational amplifier according to the magnitude of the zero-sequence current when the ground fault occurred last time according to the actual operating conditions of the power system, thereby improving the extraction ability of the weak fault zero-sequence current , to improve the accuracy of fault line selection.

2、本发明的方法采用专用的FPGA实现高速的AD采样控制，同时以DMA的方式和嵌入式处理器进行通信，实现了高速采集的同时，也实现了大数据量的存储，同时也保证了嵌入式处理器有更多的计算资源用于复杂的的故障选线算法逻辑。2, the method of the present invention adopts special-purpose FPGA to realize high-speed AD sampling control, communicates with embedded processor in the mode of DMA simultaneously, when realizing high-speed acquisition, also realized the storage of large amount of data, also guaranteed simultaneously Embedded processors have more computing resources for complex fault line selection algorithm logic.

3、本发明的方法充分重视铁磁谐振以及负荷不平衡、负荷波动等可能带来的零序电压越限误启动以及突变量误启动带来接地故障出线的误选可能，当零序电压越限时，对其幅值和频率进行判断，只有在其频率范围在49-51Hz范围以内，幅值不大于120V的情况才认为确实是接地故障导致的零序电压上升。当零序电压突变量启动时候，利用暂态强度进行判断，只有暂态强大大于2才认为是接地故障导致的零序电压突变量启动。3. The method of the present invention pays full attention to the possibility of misselection of grounding fault outlets caused by zero-sequence voltage over-limit false start caused by ferromagnetic resonance, unbalanced load, load fluctuation, etc. Only when the frequency range is within the range of 49-51Hz and the amplitude is not greater than 120V can it be considered that the zero-sequence voltage rise caused by the ground fault is indeed within the time limit. When the zero-sequence voltage mutation starts, use the transient strength to judge, only when the transient strength is greater than 2, it is considered that the zero-sequence voltage mutation starts caused by the ground fault.

4、本发明的方法充分利用小电流接地系统故障接地时的故障暂态特征和稳态故障特征的特点，综合利用暂态极性法、直流分量衰减法、稳态比幅比相法、五次谐波法、能量法多种算法进行接地故障的判别，上述五种方法有序结合，有效提升接地故障选线的准确。4. The method of the present invention makes full use of the fault transient characteristics and the characteristics of the steady state fault characteristics when the small current grounding system fault is grounded, comprehensively utilizes the transient polarity method, the DC component attenuation method, the steady state ratio amplitude ratio method, the five Multiple algorithms such as sub-harmonic method and energy method are used to distinguish ground faults. The orderly combination of the above five methods can effectively improve the accuracy of ground fault line selection.

5、本发明的方法解决了现有技术中接地故障选线方法存在的故障特征提取能力差，选线方法单一等问题，实现了自适应的根据故障特征的大小对程控运算放大器进行动态设置，利用FPGA控制AD采样芯片实现高速采样，同时利用嵌入式处理器是实现和FPGA模块之间的DMA通信，提升数据吞吐能力，从而使嵌入式处理器能够有更多的资源用于多种故障选线算法判断逻辑的综合应用。5. The method of the present invention solves the problems of poor fault feature extraction ability and single line selection method in the prior art in the ground fault line selection method, and realizes self-adaptive dynamic setting of the program-controlled operational amplifier according to the size of the fault feature. Use FPGA to control AD sampling chip to achieve high-speed sampling, and use embedded processor to realize DMA communication with FPGA module to improve data throughput, so that embedded processor can have more resources for multiple fault selection Comprehensive application of line algorithm judgment logic.

附图说明Description of drawings

图1为小电流接地系统的接地故障线路系统图；Figure 1 is a system diagram of the ground fault line of the small current grounding system;

图2为小电流接地系统的接地故障线路方法流程图。Fig. 2 is a flow chart of the ground fault line method of the small current grounding system.

具体实施方式Detailed ways

下面结合附图对本发明作进一步说明。The present invention will be further described below in conjunction with accompanying drawing.

一种小电流接地系统的接地故障选线系统A Grounding Fault Line Selection System for Small Current Grounding System

如图1所示，图1为小电流接地系统的接地故障线路系统图；本发明的系统包括零序电压互感器、零序电流互感器、二次电压变送器和二次电流变送器、可编程控制运算放大器模块、FPGA模块、AD采样模块和嵌入式处理器。As shown in Fig. 1, Fig. 1 is the grounding fault line system diagram of small current grounding system; The system of the present invention includes zero-sequence voltage transformer, zero-sequence current transformer, secondary voltage transmitter and secondary current transmitter , Programmable control operational amplifier module, FPGA module, AD sampling module and embedded processor.

零序电压互感器和零序电流互感器分别获取母线零序电压信号和馈线的零序电流信号；将电压信号和电流信号发送给二次电压变送器和二次电流变送器，由二次电压变送器和二次电流变送器分别将电压信号和电流信号转换为测量信号；再将该测量信号送到可编程控制的运算放大器，由运算放大器根据以往故障时自适应设置的放大倍数进行放大，FPGA模块对经过程控运放放大以后的测量信号通过控制AD采样模块进行高速采样，高速采样后转换为AD采样码流，以DMA的方式送到嵌入式处理器，由嵌入式处理器综合利用多种选线算法进行故障选线。The zero-sequence voltage transformer and the zero-sequence current transformer obtain the zero-sequence voltage signal of the bus and the zero-sequence current signal of the feeder respectively; send the voltage signal and current signal to the secondary voltage transmitter and the secondary current transmitter, and the two The secondary voltage transmitter and the secondary current transmitter convert the voltage signal and current signal into measurement signals respectively; then the measurement signal is sent to the programmable control operational amplifier, which is amplified by the operational amplifier according to the adaptive setting of previous faults The FPGA module performs high-speed sampling on the measurement signal amplified by the program-controlled operational amplifier by controlling the AD sampling module. After high-speed sampling, it is converted into an AD sampling code stream and sent to the embedded processor by DMA. The device comprehensively uses a variety of line selection algorithms for fault line selection.

一种小电流接地系统的接地故障选线方法A Ground Fault Line Selection Method for Small Current Grounding System

运用本发明的系统确定接地故障线路前，对本发明的系统进行初始化，具体指嵌入式处理器内部相关变量的初始化。嵌入式处理器内部相关变量的初始化，包括：每周波采样点数N，本例按故障特征提取的要求，选择为512；电压、电流的比例系数；零序电压互感器变比（实施例为35Kv/0.1Kv）,零序电流互感器变比（实施例为50/1A）；二次电压变送器规格（实施例为200V/3.53V）,二次电流变送器规格（实施例为1A/1.2V）；AD内部变比（1个码值代表0.000152587890625）；DFT变换系数，缓冲准备AD采样数据，零序电压越限启动定值、零序电流突变量启动定值。Before using the system of the present invention to determine the ground fault line, the system of the present invention is initialized, specifically referring to the initialization of relevant variables inside the embedded processor. The initialization of relevant variables inside the embedded processor includes: the number of sampling points per cycle N, which is selected as 512 according to the requirements of fault feature extraction in this example; the proportional coefficient of voltage and current; the transformation ratio of zero-sequence voltage transformer (the embodiment is 35Kv /0.1Kv), zero-sequence current transformer ratio (the embodiment is 50/1A); secondary voltage transmitter specifications (the embodiment is 200V/3.53V), secondary current transmitter specifications (the embodiment is 1A /1.2V); AD internal transformation ratio (1 code value represents 0.000152587890625); DFT transformation coefficient, buffering and preparing AD sampling data, zero-sequence voltage over-limit start-up setting, zero-sequence current mutation start-up setting value.

本发明的小电流接地系统的接地故障选线方法包括以下步骤：The grounding fault line selection method of the small current grounding system of the present invention comprises the following steps:

步骤一、零序电压互感器和零序电流互感器分别获取小电流接地系统故障时的零序电压信号和零序电流信号；Step 1, the zero-sequence voltage transformer and the zero-sequence current transformer respectively obtain the zero-sequence voltage signal and the zero-sequence current signal when the small current grounding system fails;

步骤二、二次电压变送器和二次电流变送器分别将所述电压信号和电流信号转换为故障线路识别的测量信号；Step 2, the secondary voltage transmitter and the secondary current transmitter respectively convert the voltage signal and the current signal into measurement signals for fault line identification;

步骤三、将所述测量信号经可编程运算放大器处理后发送至FPGA模块；Step 3, sending the measurement signal to the FPGA module after being processed by a programmable operational amplifier;

步骤四、FPGA模块控制AD采样模块进行高速同步采样；Step 4, the FPGA module controls the AD sampling module to perform high-speed synchronous sampling;

步骤五、所述FPGA模块采样获取的采样码流数据以成组数据传送方式（DMA方式）送到嵌入式处理器中；Step 5, the sampling code stream data acquired by the FPGA module is sent to the embedded processor in a group data transmission mode (DMA mode);

步骤六、嵌入式处理器处理所述采样码流数据；Step 6, the embedded processor processes the sampling stream data;

步骤七、接地故障选线检测。Step 7, ground fault line selection detection.

步骤一中、零序电压互感器和零序电流互感器分别获取小电流接地系统故障时的零序电压信号和零序电流信号。In step 1, the zero-sequence voltage transformer and the zero-sequence current transformer respectively obtain the zero-sequence voltage signal and the zero-sequence current signal when the small current grounding system fails.

电压互感器和电流传感器接入的是线路的零序电压和零序电流，为了能够充分对暂态故障特征进行分析，采样速率大于等于25600Hz。The voltage transformer and current sensor are connected to the zero-sequence voltage and zero-sequence current of the line. In order to fully analyze the transient fault characteristics, the sampling rate is greater than or equal to 25600Hz.

步骤二中，二次电压变送器和二次电流变送器分别将所述电压信号和电流信号转换为故障线路识别的测量信号；Instep 2, the secondary voltage transmitter and the secondary current transmitter respectively convert the voltage signal and the current signal into measurement signals for fault line identification;

步骤三中，将所述测量信号经可编程运算放大器处理后发送至FPGA模块。In Step 3, the measurement signal is sent to the FPGA module after being processed by a programmable operational amplifier.

由于小电流接地故障时，零序电流比较微弱，因此利用可编程运算放大器实现自适应的放大倍数的设置。Since the zero-sequence current is relatively weak when the small current is grounded, a programmable operational amplifier is used to realize the setting of the self-adaptive magnification.

可编程运算放大器的放大倍数根据上一次发生接地故障时零序故障电流的强弱确定，由负责进行故障识别判断的嵌入式处理器给出的。The magnification of the programmable operational amplifier is determined according to the strength of the zero-sequence fault current when the ground fault occurred last time, and is given by the embedded processor responsible for fault identification and judgment.

步骤四中，FPGA模块控制AD采样模块进行高速同步采样。In step 4, the FPGA module controls the AD sampling module to perform high-speed synchronous sampling.

FPGA模块控制的AD采样模块实现高速同步采样，由FPGA模块实现高速的AD采样，采样速率提高到25600每秒；The AD sampling module controlled by the FPGA module realizes high-speed synchronous sampling, and the FPGA module realizes high-speed AD sampling, and the sampling rate is increased to 25600 per second;

步骤五中，所述FPGA模块采样获取的采样码流数据以DMA的方式送到嵌入式处理器中。In Step 5, the sample code stream data acquired by the FPGA module is sent to the embedded processor by DMA.

由于实际小电流接地系统中接入的线路比较多，FPGA模块以25600每秒的采样速率进行采样，所产生的实时数据量很大，采取DMA的方式将采样数据送到嵌入式系统，减少嵌入式系统进行数据搬移所耗费的资源，从而嵌入式系统能够有更多的资源用于故障选线的算法逻辑。Since there are many lines connected to the actual low-current grounding system, the FPGA module samples at a sampling rate of 25600 per second, which generates a large amount of real-time data. The sampled data is sent to the embedded system by DMA to reduce embedded The resources consumed by the embedded system for data movement, so that the embedded system can have more resources for the algorithm logic of fault line selection.

步骤六中，所述嵌入式处理器处理所述采样码流数据，具体包括以下步骤；In step 6, the embedded processor processes the sampling stream data, specifically including the following steps;

嵌入式处理器获取FPAG以DMA方式送达的AD采样码流数据后进行FFT计算（快速傅里叶变换，Fast Fourier Transform）。The embedded processor obtains the AD sampling code stream data delivered by FPAG in DMA mode and then performs FFT calculation (Fast Fourier Transform, Fast Fourier Transform).

FFT计算活的零序电压的基波幅值信息、基波相位信息、五次谐波幅值信息、五次谐波相位信息和零序电压的频率。FFT calculates the fundamental wave amplitude information, fundamental wave phase information, fifth harmonic amplitude information, fifth harmonic phase information and the frequency of zero sequence voltage of live zero sequence voltage.

步骤七中，接地故障选线检测，具体包括以下步骤：In step seven, the ground fault line selection detection specifically includes the following steps:

1、根据获得的数据和以往缓冲的数据进行突变量检测，当突变量启动并且零序电压越限且小于120V，同时零序电压频率在49-51Hz范围内时，进行接地故障线路逻辑分析，具体如图2所示，图2为小电流接地系统的接地故障线路方法流程图；1. Carry out sudden change detection based on the obtained data and previous buffered data. When the sudden change starts and the zero-sequence voltage exceeds the limit and is less than 120V, and the zero-sequence voltage frequency is within the range of 49-51Hz, the logic analysis of the ground fault line is carried out. Specifically as shown in Figure 2, Figure 2 is a flow chart of the ground fault line method of the small current grounding system;

2、当零序电压突变量启动后，对突变量启动时刻前半周波和后半周波的数据进行存储，对所有线路的暂态能量进行排序，暂态能量为缓存的一周波采样点数据的绝对值之和，对选出暂态能量前三大的线路进行暂态强度检测，发现其暂态强度TI大于2时，利用暂态极性方法对表征线路接地故障特征的零序电流进行判断，选出故障线路；2. When the zero-sequence voltage mutation is started, store the data of the first half cycle and the second half cycle at the time of the mutation start, sort the transient energy of all lines, and the transient energy is the absolute value of the buffered cycle sampling point data The sum of the values, the transient strength detection is performed on the top three lines selected from the transient energy, and when the transient strength TI is found to be greater than 2, the zero-sequence current that characterizes the ground fault characteristics of the line is judged by using the transient polarity method. Select the fault line;

暂态极性transient polarity

利用小电流接地故障瞬间，故障线路的零序电流的方向和非故障线路的零序电流方向是相反的，且在接地的瞬间这种暂态极性比较明显，同时为避免由于电流系统运行的不对称性、CT的不平衡性带来的误差，利用所述的暂态强度的概念对故障现象进行区分，只有暂态强大大于2时，才认为可以利用暂态极性方法。At the instant of a small current grounding fault, the direction of the zero-sequence current of the fault line is opposite to that of the non-fault line, and the transient polarity is more obvious at the moment of grounding. For errors caused by asymmetry and CT imbalance, use the concept of transient strength to distinguish fault phenomena. Only when the transient strength is greater than 2, can the transient polarity method be used.

当暂态特征不够充分，暂态强度TI小于2时，对零序电压的相位进行判断，当判断出零序电压在过零点附近时，同时小电流接地系统存在消弧线圈接地，则利用检测故障信息中的衰减直流分量判断，若暂态故障特征比较明显的前三大线路中，一条线路的衰减直流大于另外两条线路衰减直流之和时，则认为衰减直流分量大的该线路就为故障线路，进入步骤4；When the transient characteristics are not sufficient and the transient intensity TI is less than 2, the phase of the zero-sequence voltage is judged. When it is judged that the zero-sequence voltage is near the zero-crossing point, and there is an arc-suppression coil grounding in the small-current grounding system, use the detection Judging the attenuated DC component in the fault information, if among the top three lines with obvious transient fault characteristics, the attenuated DC of one line is greater than the sum of the attenuated DC of the other two lines, then the line with the large attenuated DC component is considered to be Faulty line, go to step 4;

零序电压过零点附近的判断依据：利用零序电压和零序电流之间的相位差进行判断，图2中theta为电压和电流之间的相位角差，当60<theta<120或-120<theta<-60认为其属于过零点附近的范围；Judgment basis near the zero-sequence voltage zero-crossing point: use the phase difference between zero-sequence voltage and zero-sequence current to judge, theta in Figure 2 is the phase angle difference between voltage and current, when 60<theta<120 or -120 <theta<-60 thinks it belongs to the range near the zero crossing point;

3、当暂态强度TI小于2时，小电流接地系统不存在消弧线圈接地，首先对每周波计算得到的各线路的零序电流的幅值进行排序选择，选出幅值前三大的线路；3. When the transient intensity TI is less than 2, there is no arc-suppression coil grounding in the small current grounding system. First, sort and select the amplitudes of the zero-sequence currents of each line calculated by the weekly wave, and select the top three amplitudes. line;

将选出的前三大零序电流幅值的线路相位和零序电压的相位进行比较，当某一线路和零序电压相位相反时，则认为该线路为故障线路；Compare the line phases of the selected top three zero-sequence current amplitudes with the phases of the zero-sequence voltage. When a line is opposite to the phase of the zero-sequence voltage, the line is considered to be a faulty line;

同时根据最大的零序电流码值进行程控运放倍数的计算，使下次发生接地故障的时候，程控运放的放大倍数处于一个合适的状态，确保下次接地故障时，故障特征能够通过程控运放得到很好的放大；进入步骤5；At the same time, the program-controlled operational amplifier multiple is calculated according to the maximum zero-sequence current code value, so that the next time a ground fault occurs, the program-controlled operational amplifier's amplification factor is in a suitable state, ensuring that the fault feature can be controlled by the program when the next ground fault occurs. The op amp is well amplified; go to step 5;

4、步骤2中的选线判断连续进行3次，当3次的结果都一致的时候，则认为该选线结果正确；4. The line selection judgment instep 2 is carried out 3 times in a row. When the results of the 3 times are consistent, the line selection result is considered correct;

当3次选线结果不一致时，若小电流接地系统为有消弧线圈接地时，则检测其零序电流中五次谐波电流，根据五次谐波电流的大小，对各个线路进行排序，选出前三大线路；When the results of the three times of line selection are inconsistent, if the small current grounding system is grounded with an arc suppression coil, then detect the fifth harmonic current in its zero sequence current, and sort each line according to the magnitude of the fifth harmonic current. Select the top three routes;

当五次谐波电流最大的那条线路的五次谐波电流与其基波电流的比值大于8%时，则将选出的五次谐波电流前三大的线路的相位与零序电压的五次谐波相位进行比较，当某一条线路的五次谐波电流和零序电压的五次谐波相位相反时，则认为该线路为故障线路；When the ratio of the fifth harmonic current of the line with the largest fifth harmonic current to its fundamental current is greater than 8%, the phase of the selected top three lines with the fifth harmonic current and the phase of the zero-sequence voltage Compared with the fifth harmonic phase, when the fifth harmonic current of a certain line is opposite to the fifth harmonic phase of the zero sequence voltage, the line is considered to be a faulty line;

5、当步骤3中的利用五次谐波选线判断连续进行3次，如果3次的结果都一致的时候，则认为该选线结果正确；5. When the fifth harmonic line selection judgment in step 3 is carried out 3 times in a row, if the results of the 3 times are consistent, the line selection result is considered correct;

若3次选线结果不一致，当小电流接地系统有消弧线圈接地时，则利用能量法对步骤2中检测的前三大线路进行选线，前三大线路中一条线路的有功大于另两条线路的有功和，则认为是该条线路接地故障；If the results of the three line selections are inconsistent, when the small current grounding system has an arc suppressing coil grounded, use the energy method to select the first three lines detected instep 2, and the active power of one line in the first three lines is greater than that of the other two active sum of a line, it is considered to be a ground fault of the line;

6、如果上述的2、3、4、5步骤中的选线均不成立，认为接地故障不是线路接地，则认为是母线接地故障。6. If the line selection in theabove steps 2, 3, 4, and 5 is not established, it is considered that the ground fault is not a line ground fault, and it is considered a bus ground fault.

最后应当说明的是：以上实施例仅用以说明本发明的技术方案而非对其限制，尽管参照上述实施例对本发明进行了详细的说明，所属领域的普通技术人员应当理解：依然可以对本发明的具体实施方式进行修改或者等同替换，而未脱离本发明精神和范围的任何修改或者等同替换，其均应涵盖在本发明的权利要求范围当中。Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (5)

1. a ground fault line selecting method for small current neutral grounding system, is characterized in that: said method comprising the steps of:

Residual voltage signal and zero sequence current signal when I, zero sequential potential transformer and zero sequence current mutual inductor obtain low current neutral grounding system fault respectively;

II, secondary voltage transmitter and secondary current transmitter are converted to by described voltage signal and current signal the measuring-signal that faulty line is identified respectively;

III, described measuring-signal after processing, programmable operational amplifier is sent to FPGA module;

IV, FPGA module controls AD sampling module carry out high-speed synchronous sampling;

The sampling bit stream data that V, described FPGA module samples are obtained is delivered in flush bonding processor in the mode of DMA;

VI, described flush bonding processor are processed described sampling bit stream data;

VII, earth fault line selection detect.

2. the ground fault line selecting method of a kind of small current neutral grounding system as claimed in claim 1, it is characterized in that: in described Step II I, the enlargement factor of described programmable operational amplifier by the flush bonding processor that carries out Fault Identification judgement during according to earth fault the power of zero-sequence fault electric current determine.

3. the ground fault line selecting method of a kind of small current neutral grounding system as claimed in claim 1, it is characterized in that: in described step IV, described FPGA module controls AD sampling module carries out high-speed synchronous sampling, and described FPGA module realizes high-speed AD sampling, and sampling rate is 25600 per second.

4. the ground fault line selecting method of a kind of small current neutral grounding system as claimed in claim 1, it is characterized in that: in described step VI, described flush bonding processor carries out effective value and phase information to described sampling bit stream data and calculates, and comprises the calculating of frequency of fundamental voltage amplitude information, fundamental phase information, quintuple harmonics amplitude information, quintuple harmonics phase information and the residual voltage of residual voltage.

5. the ground fault line selecting method of a kind of small current neutral grounding system as claimed in claim 4, is characterized in that: described step VII comprises the following steps:

S701, according to the data of described step VI and buffered data, carry out residual voltage transient detection, when residual voltage Sudden Changing Rate starts and the out-of-limit earth fault line selection logic that enters of residual voltage;

S702, when residual voltage Sudden Changing Rate starts, obtain transient state energy the sequence of all circuits, the circuit of first three large transient state energy is carried out to transient state intensity detection;

When transient state intensity is greater than 2, use transient state polarity methods analyst to characterize the zero-sequence current of line-to-ground fault feature, determine faulty line;

When transient state intensity is less than 2, analyze the phase place of residual voltage, when residual voltage is during near zero-crossing point, judge whether small current system exists grounding through arc, exist and determine attenuating dc component, in first three obvious transient fault characteristic line, the circuit that attenuating dc component is greater than another two Line Attenuation DC component sums is faulty line, enters step S704; Otherwise enter step S703;

S703, when transient state intensity is less than 2, there is not grounding through arc in small current neutral grounding system, determines the circuit of first three large every cycle zero-sequence current amplitude, the contrast phase place of circuit and the phase place of residual voltage;

If the phase place of certain circuit and residual voltage single spin-echo, think faulty line; Obtain the enlargement factor of its zero-sequence current code value, while guaranteeing next earth fault, fault signature amplifies with described enlargement factor; Enter step S705;

S704, the continuous route selection judgement of carrying out for 3 times in step S702, if result is consistent, think that route selection is correct;

Otherwise the circuit of quintuple harmonics electric current maximum in zero-sequence current when obtaining small current neutral grounding system and having grounding through arc, judge whether the quintuple harmonics electric current of this circuit and the ratio of fundamental current are greater than 8%, be greater than and compare the phase place of first three large circuit of quintuple harmonics electric current and the quintuple harmonics phase place of residual voltage, think that the circuit of quintuple harmonics single spin-echo of quintuple harmonics electric current and residual voltage is faulty line; Enter step S703;

S705, carry out in step S703 quintuple harmonics route selection judgement for 3 times continuously, if result is consistent, think that route selection is correct;

Otherwise while obtaining small current neutral grounding system grounding through arc, utilize energy method to carry out route selection to first three large circuit of quintuple harmonics electric current in described step S702, think that the circuit that active power is greater than another two circuit sums is faulty line;

If S706 above-mentioned steps S702, S703, S7604 and S705 route selection failure, think busbar grounding fault.

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