配电网小电流接地系统故障选线方法 技术领域 Fault line selection method for small current grounding system of distribution network
本发明涉及一种配电网变电站小电流接地系统故障选线方法，特别适用于中性 点经消弧线圈接地系统， 属于电力自动化技术领域。 背景技术 The invention relates to a fault line selection method for a small current grounding system of a distribution network substation, and is particularly suitable for a neutral point arc suppression coil grounding system, and belongs to the field of power automation technology. Background technique
在 6~66kV的配电网系统中，中性点多采用经消弧线圈接地方式，该接地方式可 以有效地抑制弧光接地故障， 降低系统的过电压水平， 但由于消弧线圈的补偿作用， 系统发生接地故障时， 故障电流较小， 给故障选线带来了困难。 目前， 现有的故障选 线原理多采用零序电流五次谐波法、小扰动法、暂态电流首半波法。 由于配电网小电 流接地系统故障电流较小、 电网结构复杂的特点，故障信号量复杂多变，判定方法过 于简单， 导致故障选线准确率较低。 In the distribution network system of 6~66kV, the neutral point adopts the grounding mode of the arc suppression coil. This grounding method can effectively suppress the arc grounding fault and reduce the overvoltage level of the system. However, due to the compensation effect of the arc suppression coil, When a ground fault occurs in the system, the fault current is small, which brings difficulties to the fault line selection. At present, the existing fault line selection principle mostly uses the zero-sequence current fifth harmonic method, the small disturbance method, and the transient current first half wave method. Due to the small fault current of the small current grounding system of the distribution network and the complex structure of the power grid, the fault signal quantity is complex and variable, and the determination method is too simple, resulting in low accuracy of fault line selection.
经对现有技术领域的检索发现， 中国专利申请号 200510010793. 6, 记载了 "一 种消弧线圈接地系统故障选线自适应方法"，采用零序电流和母线电压在故障时的变 化特征，判定故障线路，利用数字仿真该方法可能有效，但实际电网中零序电流较小， 外界干扰较大,故障选线准确率低。 中国专利申请号 200610038831. 3, 记载了 "适用 于快速自动消弧线圈接地系统的选线新方法"，该方法采用暂态零序电流识别故障线 路， 当故障点的过渡电阻较大时， 暂态电流很小，此时的故障选线准确率很低。 中国 专利申请号 200810155794. 3,记载了一种 "适用于消弧线圈接地电网的选线方法"， 该方法采用馈线的零序电流和消弧线圈补偿电流作为故障判定信号量，利用各馈线上 信号特征值的正负判定故障线路，该方法仍然利用信号量较小的零序电流，在电网系 统受干扰的情况下， 将出现信号特征值出现矛盾的情况， 导致故障选线不准确。 According to the search in the prior art, Chinese Patent Application No. 200510010793. 6, describes "a self-adaptive method for fault line selection of arc suppression coil grounding system", which adopts the characteristics of zero sequence current and bus voltage variation at the time of failure. It is possible to determine the faulty line by digital simulation. However, the zero-sequence current in the actual power grid is small, the external interference is large, and the fault line selection accuracy is low. China Patent Application No. 200610038831. 3, describes "a new method for line selection for fast automatic arc suppression coil grounding system", which uses transient zero sequence current to identify fault lines. When the transition resistance of the fault point is large, The state current is very small, and the fault line selection accuracy at this time is very low. Chinese Patent Application No. 200810155794. 3, describes a "line selection method suitable for arcing coil grounding grid", which uses the zero sequence current of the feeder and the arc suppression coil compensation current as the fault determination signal amount, using each feeder line The positive and negative of the signal characteristic value determine the fault line. The method still uses the zero-sequence current with a small signal amount. In the case of interference of the power grid system, a contradiction occurs in the signal characteristic value, resulting in inaccurate fault line selection.
上述现有技术采用传统的电气信号监测方法，在较简单的电网中，虽然能够对故 障点接地电阻较小的接地故障进行准确选线,但在较为复杂的小电流接地系统的实际 使用中存在着一定的局限性， 故障选线准确率较低。 发明内容 The above prior art adopts the traditional electrical signal monitoring method. In a relatively simple power grid, although the ground fault with a small grounding resistance at the fault point can be accurately selected, it exists in the practical use of a relatively complicated small current grounding system. With certain limitations, the accuracy of fault line selection is low. Summary of the invention
本发明针对现有技术存在的上述不足，提供一种配电网小电流接地系统故障选线 方法，避免了现有故障选线方法在小电流接地系统中应用上的不足，故障判定信号量 较大， 故障选线准确率较髙， 是小电流接地系统中比较理想的故障选线方法。
本发明涉及配电网小电流接地系统故障选线方法， 包括以下步骤： The invention provides a fault line selection method for a small current grounding system of a distribution network in view of the above-mentioned deficiencies of the prior art, and avoids the shortage of the existing fault line selection method in a small current grounding system, and the fault determination signal amount is compared. Large, fault line selection accuracy is relatively low, is an ideal fault line selection method in small current grounding system. The invention relates to a fault line selection method for a small current grounding system of a distribution network, comprising the following steps:
第一步、将并联电阻接在配电网中的变压器的中性点与地之间，并与消弧线圈并 联连接； 真空接触器串联在并联电阻所在的支路中， 以控制并联电阻的投切； 在所述 中性点接单相电压互感器， 以测量该中性点的电压；在配电网中的变电站母线的各出 线上接零序电流互感器， 以检测各出线的零序电流； The first step is to connect the parallel resistor between the neutral point of the transformer in the distribution network and the ground, and connect it in parallel with the arc suppression coil; the vacuum contactor is connected in series in the branch where the parallel resistor is located to control the parallel resistance. Switching; connecting a single-phase voltage transformer at the neutral point to measure the voltage of the neutral point; connecting zero-sequence current transformers on each outgoing line of the substation busbar in the distribution network to detect zero of each outgoing line Sequence current
所述的并联电阻为功率电阻；所述的真空接触器为永磁结构的高压交流真空接触 器；所述的单相电压互感器为电磁式单相电压互感器；所述的零序电流互感器为开口 式零序电流互感器。 The parallel resistance is a power resistor; the vacuum contactor is a high-voltage AC vacuum contactor with a permanent magnet structure; the single-phase voltage transformer is an electromagnetic single-phase voltage transformer; the zero-sequence current mutual inductance The device is an open zero sequence current transformer.
第二步、当配电网系统发生永久性接地故障时，真空接触器在设定时间内投切并 联电阻；控制器通过单相电压互感器测量所述中性点的电压，同时通过零序电流互感 器检测在并联电阻投切前后母线上各条出线的零序电流； In the second step, when a permanent ground fault occurs in the distribution network system, the vacuum contactor switches the parallel resistance within a set time; the controller measures the voltage of the neutral point through the single-phase voltage transformer, and passes the zero sequence The current transformer detects the zero sequence current of each outgoing line on the busbar before and after the parallel resistance is switched;
所述的配电网系统发生永久性接地故障的判定方法为：当配电网系统的中性点电 压高于配电网系统的相电压的 30%， 并且这种过电压状态在 5秒内不能自行消除， 则 判定配电网系统发生了永久性接地故障； 所述的设定时间为 0. 3-0. 8秒。 The method for determining a permanent ground fault of the distribution network system is: when the neutral point voltage of the distribution network system is higher than 30% of the phase voltage of the distribution network system, and the overvoltage state is within 5 seconds 8秒。 The set time is 0. 3-0. 8 seconds.
所述控制器是以 PC104总线嵌入式模块、 DSP模块为核心元件的智能装置。 第三步、控制器根据采样到的中性点的电压和各出线的零序电流，利用故障线路 判定方法实现故障选线。 The controller is a smart device with a PC104 bus embedded module and a DSP module as core components. In the third step, the controller uses the fault line determination method to implement the fault line selection according to the sampled neutral point voltage and the zero sequence current of each outgoing line.
所述的故障线路判定方法是指： The fault line determination method refers to:
1 )在发生永久性接地故障时， 首先计算各出线上的零序电流相角之差的特征值 te[m , t ]表达式为： te[m] = j \ 0I [m] - 0I [i] \ 其中： Ν为母线上出线的总数值， m为小于等于 Ν的正整数， [m]为第 m条出线 投切并联电阻前后的零序电流相角的差值， 的表达式为：
1) In the event of a permanent ground fault, first calculate the eigenvalue t e [m , t ] of the difference between the zero-sequence current phase angles on each outgoing line as: t e [m] = j \ 0 I [m] - 0 I [i] \ where: Ν is the total value of the outgoing line on the bus, m is a positive integer less than or equal to ,, [m] is the difference between the phase angles of the zero-sequence current before and after switching the parallel resistance of the m-th outgoing line, The expression is:
其中： [m]为投切并联电阻后第 m条出线段上的零序电流相角， 为投切并 联电阻前第 m条出线段上的零序电流相角。 Where: [m] is the zero-sequence current phase angle on the m-th line segment after switching the shunt resistor, which is the zero-sequence current phase angle on the m-th line segment before the parallel-connected resistance.
2 )然后从各条出线中选出具有最大的特征值 以及次最大的特征值 的两 条出线，并将这两条出线分别标记为第 X条出线段和第 y条出线段，其中 X和 y为小 于等于 N的正整数。 页 (细则 26条）
3) 当 x]和 tf [y]满足 0·9 < < 1 · 1时， 则认为所述母线发生永久性接地2) then select the two outgoing lines with the largest eigenvalue and the second largest eigenvalue from each of the outgoing lines, and mark the two outgoing lines as the Xth outgoing line segment and the yth outgoing line segment, where X and y is a positive integer less than or equal to N. Page (Article 26) 3) When x] and t f [y] satisfy 0·9 << 1 · 1, the bus is considered to be permanently grounded.
故障， 否则判定第 X条出线为故障出线， 即第 X条出线发生永久性接地故障 附图说明 Fault, otherwise it is determined that the Xth outlet is the faulty outlet, that is, the permanent ground fault occurs in the Xth outlet.
为了使本发明的内容更容易被清楚的理解， 下面根据具体的实施例并结合附图， 对本发明作进一步详细的说明， 其中 In order to make the content of the present invention easier to understand, the present invention will be further described in detail below with reference to the specific embodiments,
图 1为实施例中的配电网小电流接地系统的结构示意图。 具体实施方式 FIG. 1 is a schematic structural view of a small current grounding system of a distribution network in an embodiment. detailed description
下面对本发明的实施例作详细说明：本实施例在以本发明技术方案为前提下进行 实施，给出了详细的实施方式和具体的操作过程，但本发明的保护范围不限于下述的 实施例。 The embodiments of the present invention are described in detail below. The present embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation procedures are given, but the scope of protection of the present invention is not limited to the following implementation. example.
本实施例包括以下步骤： This embodiment includes the following steps:
第一步、如图 1所示， 并联电阻 4和真空接触器 5串联后连接于变电站的变压器 1的中性点与地之间， 单相电压互感器 2与所述中性点相连， 消弧线圈 3接在变压器 1的中性点与地之间， 母线 6的每一条出线上都安装了零序电流互感器 7。 所谓母线 是电站或变电站输送电能用的总导线。通过母线，把发电机、变压器或整流器输出的 电能输送给各个用户或其他变电所。 所谓出线是从上述母线分配出去的线路。 In the first step, as shown in FIG. 1, the parallel resistor 4 and the vacuum contactor 5 are connected in series and connected between the neutral point of the transformer 1 of the substation and the ground, and the single-phase voltage transformer 2 is connected to the neutral point. The arc coil 3 is connected between the neutral point of the transformer 1 and the ground, and the zero-sequence current transformer 7 is mounted on each of the outgoing lines of the bus bar 6. The so-called busbar is the total conductor used to transport electrical energy from a power station or substation. The power output from the generator, transformer or rectifier is supplied to individual users or other substations via the bus. The so-called outlet is the line that is allocated from the above bus.
所述的并联电阻 4的阻值根据配电网的系统电压选定，并联电阻 4的阻值为系统 相电压与 10A电流的比值， 例如： 10kV系统， 该系统的相电压为 6062V, 则并联电阻 4的阻值为 606. 2欧姆， 该并联电阻 4的电阻类型为功率电阻。 The resistance of the parallel resistor 4 is selected according to the system voltage of the distribution network, and the resistance of the parallel resistor 4 is the ratio of the system phase voltage to the 10A current, for example: 10kV system, the phase voltage of the system is 6062V, then parallel The resistance of the resistor 4 is 606.2 ohms, and the resistance type of the parallel resistor 4 is a power resistor.
所述的真空接触器 5为永磁结构的髙压交流真空接触器，用于在配电网系统发生 单相接地故障时， 及时投切并联电阻 4。 The vacuum contactor 5 is a permanent magnet structure of a rolling AC vacuum contactor for timely switching the parallel resistor 4 when a single-phase ground fault occurs in the distribution network system.
所述的单相电压互感器 2为电磁式单相电压互感器,用于测量系统的中性点电压。 所述的零序电流互感器 7为开口式零序电流互感器，用于在配电网系统发生单相 接地故障时， 测量各出线的零序电流。 The single-phase voltage transformer 2 is an electromagnetic single-phase voltage transformer for measuring the neutral point voltage of the system. The zero-sequence current transformer 7 is an open-type zero-sequence current transformer for measuring the zero-sequence current of each outgoing line when a single-phase ground fault occurs in the distribution network system.
所述的消弧线圈 3为调匝式、 调容式或髙短路阻抗式消弧线圈。 The arc suppression coil 3 is a chirped, tunable or 髙 short circuit impedance arc suppression coil.
第二步、 当所述中性点电压髙于系统相电压的 30%并持续 5秒， 系统的过电压状 态并未消除， 则判定配电网系统发生了永久性接地故障； 然后投切并联电阻 4, 并联 电阻 4的投切时间为 0. 5秒；控制器根据采集到的各出线上的零序电流信号，进行故 障线路判定。 替换页（细则第 26条）
所述的控制器是以 PC104总线嵌入式模块和 DSP芯片为核心元件的智能装置。 第三步、 若所述出线有 15条线路， 计算各出线在并联电阻 4投切前后的零序电 流相角之差 的表达式为：In the second step, when the neutral point voltage is at 30% of the system phase voltage for 5 seconds, the overvoltage state of the system is not eliminated, and a permanent ground fault occurs in the distribution network system; The switching time of the resistor 4 and the parallel resistor 4 is 0.5 seconds; the controller performs fault line determination according to the zero-sequence current signals on the collected outgoing lines. Replacement page (Article 26) The controller is a smart device with a PC104 bus embedded module and a DSP chip as core components. The third step, if there are 15 lines in the outlet, the expression for calculating the difference between the zero-sequence current phase angles of the respective outlet lines before and after the parallel resistance 4 is cut is:
其中， 为在投切并联电阻前第 m条出线段上的零序电流相角， 为在投 切并联电阻后第 m条出线段上的零序电流相角。 所述的 15条出线在并联电阻 4投切 前后的零序电流相角之差依次为： 、 、 ... ^； 然后， 计算出所述 15条 出线在并联电阻 4投切前后的零序电流相角之差的特征值 , 表达式为：
因此， 15条出线的在并联电阻 4投切前后的零序电流相角之差的特征值依次为Wherein, the zero-sequence current phase angle on the m-th line segment before the parallel resistance is switched is the zero-sequence current phase angle on the m-th line segment after the parallel resistance is switched. The difference between the zero-sequence current phase angles of the 15 outgoing lines before and after the parallel resistance 4 is cut is: , , ... ^; Then, the 15 outgoing lines are calculated. The characteristic value of the difference between the phase angles of the zero-sequence currents before and after the shunt resistor 4 is switched, and the expression is: Therefore, the characteristic values of the difference between the zero-sequence current phase angles of the 15 outgoing lines before and after the shunt resistor 4 is switched are
、 、 ... ΐ5];若其中 为最大值、 为次最大值；则计算 ]与  的比值的绝对值， 如果该比值的绝对值在（0.9， 1.1)区间内， 则判定母线发生接地 故障， 否则判定第 5条出线为故障线路。 , , ... ΐ5] ; if [ 5 ] is the maximum value and [ 9 ] is the next maximum value, then calculate the absolute value of the ratio of [ 5 ]] to [ 9 ], if the ratio If the absolute value is within the range of (0.9, 1.1), it is determined that the bus has a ground fault, otherwise the fifth line is determined to be the faulty line.
本实施例与现有的故障选线方法相比，本实施例通过借助并联电阻，取得较大的 故障信号特征值，故障判定原理直观，并且判定方法不受系统参数的限制和信号的干 扰， 故障选线准确率较髙。 Compared with the existing fault line selection method, the present embodiment obtains a large fault signal characteristic value by means of a parallel resistor, and the fault determination principle is intuitive, and the determination method is not limited by system parameters and signal interference. The accuracy of fault line selection is relatively low.
工业应用性 Industrial applicability
本发明借助并联电阻实现小电流接地系统故障选线，克服了配电网小电流接地系 统故障电流较小、不易判定故障的缺点，提髙了故障定位准确性； 本故障选线方法通 过并联电阻获取各出线的零序电流相角变化特征值， 根据这一特征值进行故障判定， 与电网系统参数和接地故障类型无关，不受系统干扰， 故障选线准确性髙，是小电流 接地系统中比较可靠的故障选线方法。 The invention realizes the fault line selection of the small current grounding system by means of the parallel resistance, overcomes the shortcomings of the fault current of the small current grounding system of the distribution network, and is difficult to determine the fault, and improves the fault positioning accuracy; the fault line selection method passes the parallel resistor Obtain the characteristic value of the zero-sequence current phase angle variation of each outgoing line, and judge the fault according to this characteristic value, which is independent of the grid system parameters and the ground fault type, is not affected by the system, and the fault line selection accuracy is 髙, which is in the small current grounding system. More reliable fault line selection method.
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