CN105242163A - Wire selection checking method of substation DC grounding inspection - Google Patents

Wire selection checking method of substation DC grounding inspection Download PDF

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CN105242163A
CN105242163A CN201510418985.4A CN201510418985A CN105242163A CN 105242163 A CN105242163 A CN 105242163A CN 201510418985 A CN201510418985 A CN 201510418985A CN 105242163 A CN105242163 A CN 105242163A
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branch
positive
grounding
ground
line selection
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CN105242163B (en
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徐楠
雷兴
黄震宇
许昭德
盛炜
张雯
刘高原
石天宇
江志清
姜贞
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SHENZHEN AUTO ELECTRIC POWER PLANT CO Ltd
State Grid Shanghai Electric Power Co Ltd
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SHENZHEN AUTO ELECTRIC POWER PLANT CO Ltd
State Grid Shanghai Electric Power Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04SSYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52Outage or fault management, e.g. fault detection or location

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  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

一种变电站直流接地巡检的选线校核方法,涉及探测电缆、传输线或网络中电故障的方法,尤其涉及一种用于探测变电站直流系统接地故障的方法,包括以下步骤:采用电桥法进行母线或支路接地巡检;根据故障前、后电流电压的状态量和接地电阻的计算量,以及三者的电气联系,进行故障特征辨识,采用基于逻辑事件驱动的自动巡检模式,兼顾平衡电桥的快速性和不平衡电桥的容错性,提高查找速度和容错水平,实现快速诊断并排除故障。将选线校核功能集成到变电站直流接地巡检装置中,通过逻辑判断调用不平衡电桥模式来辨识零漂和故障支路,快速识别直流接地巡检装置的误选或漏选,在不增加硬件成本的前提下提高巡检装置的性能。

A line selection and verification method for substation direct current grounding inspection, which relates to a method for detecting electrical faults in cables, transmission lines or networks, in particular to a method for detecting ground faults in substation direct current systems, comprising the following steps: using the bridge method Carry out bus or branch grounding inspection; according to the state quantity of current and voltage before and after the fault, the calculation amount of grounding resistance, and the electrical connection between the three, fault feature identification is carried out, and the automatic inspection mode driven by logic events is adopted, taking into account The rapidity of the balanced bridge and the fault tolerance of the unbalanced bridge improve the search speed and fault tolerance level, and realize rapid diagnosis and troubleshooting. Integrate the line selection check function into the DC ground inspection device of the substation, call the unbalanced bridge mode through logical judgment to identify zero drift and faulty branches, and quickly identify the misselection or omission of the DC ground inspection device. Improve the performance of the inspection device under the premise of increasing the hardware cost.

Description

一种变电站直流接地巡检的选线校核方法A line selection and checking method for substation DC grounding inspection

技术领域 technical field

本发明涉及探测电缆、传输线或网络中电故障的方法,尤其涉及一种用于探测变电站直流系统接地故障的方法,以及使用该方法的装置或系统。 The present invention relates to a method for detecting electrical faults in cables, transmission lines or networks, in particular to a method for detecting ground faults in DC systems of substations, and a device or system using the method.

背景技术 Background technique

直流电源系统是变电站内三大隐蔽工程之一,直流电源作为电力系统的重要组成部分,为一些重要常规负荷、继电保护及自动装置、远动通讯装置提供不间断供电电源,并提供事故照明电源。直流电源系统发生一点接地,不会产生短路电流,系统可以继续运行。但是,必须及时查找接地点并尽快消除接地故障,否则当发生另一点接地时,就有可能引起信号装置、继电保护及自动装置、断路器的误动作或拒绝动作,有可能造成直流电源短路,引起熔断器熔断,或快分电源开关断开,使设备失去操作电源,引发电力系统严重故障乃至事故。因此,不允许直流电源系统在一点接地情况下长时间运行,必须对直流电源系统进行在线监测,实现快速故障诊断和状态评估,迅速查找并排除接地故障,杜绝因直流电源系统接地而引起的电力系统故障。对直流电源系统进行在线监测的故障支路选线方法,主要分为交流法和直流电桥法。交流法也称为低频信号注入法,交流法利用交流信号和互感器测量的交流电流信号计算支路绝缘电阻值,不能定位正极或负极接地;此外,低频信号注入法会因系统分布电容过大而误选,且环网方式时会造成支路存在谐波环流,目前主要用于便携式接地电阻测试仪。中国发明专利“高抗干扰能力的直流电源系统接地故障检测方法”(发明专利号:ZL201310063104.2授权公告号:CN103091606B)公开了一种采用交流信号注入法监测直流电源系统的接地故障的检测方法,包括以下步骤:步骤一、每隔一段时间,在直流电源系统母线和大地之间注入频率低于工频的低频交流电流信号,步骤二、在确定的故障支路上测量获得电流信号,利用谐波提取单元,并采用加窗插值法获得电流信号中的各个频率分量的信号,步骤三、比对步骤一注入的低频交流电流信号和步骤二获取的电流信号中的各个频率分量的信号,确定注入的低频交流信号对应频率分量信号消失的地方,该处即为故障点。 The DC power supply system is one of the three hidden projects in the substation. As an important part of the power system, the DC power supply provides uninterrupted power supply for some important conventional loads, relay protection and automatic devices, telecontrol communication devices, and provides emergency lighting. power supply. A point of grounding occurs in the DC power system, no short-circuit current will be generated, and the system can continue to operate. However, it is necessary to find the grounding point in time and eliminate the grounding fault as soon as possible, otherwise, when another point is grounded, it may cause malfunction or rejection of the signal device, relay protection, automatic device, and circuit breaker, and may cause a short circuit of the DC power supply , causing the fuse to blow, or the power switch to be disconnected quickly, so that the equipment loses operating power, causing serious failures and even accidents in the power system. Therefore, the DC power system is not allowed to run for a long time under the condition of one point grounding, and the DC power system must be monitored online to realize rapid fault diagnosis and status evaluation, quickly find and eliminate grounding faults, and prevent power failures caused by grounding of the DC power system. system error. The fault branch line selection methods for on-line monitoring of DC power systems are mainly divided into AC method and DC bridge method. The AC method is also called the low-frequency signal injection method. The AC method uses the AC signal and the AC current signal measured by the transformer to calculate the insulation resistance value of the branch circuit, and cannot locate the positive or negative grounding; However, if it is wrongly selected, and the ring network mode will cause harmonic circulation in the branch, it is mainly used for portable grounding resistance testers at present. Chinese invention patent "High anti-interference ability DC power system ground fault detection method" (invention patent number: ZL201310063104.2 authorized announcement number: CN103091606B) discloses a detection method for monitoring DC power system ground faults using AC signal injection method , including the following steps: Step 1. At regular intervals, inject a low-frequency AC current signal with a frequency lower than the power frequency between the bus bar of the DC power supply system and the ground. Step 2. Measure the current signal on the determined fault branch, and use the harmonic Wave extraction unit, and use the window interpolation method to obtain the signal of each frequency component in the current signal, step 3, compare the low-frequency AC current signal injected in step 1 and the signal of each frequency component in the current signal obtained in step 2, and determine The injected low-frequency AC signal corresponds to the place where the frequency component signal disappears, which is the fault point.

直流电桥法不受分布电容影响,检测灵敏度较高,被微机绝缘检测仪广泛采用。中国发明专利申请“一种直流电源系统绝缘监测方法及其设备”(发明专利申请号:201310063104.2公开号:CN103018614A)公开了一种直流电源系统绝缘监测方法及其设备,用于解决现有技术中存在的直流电源系统的监测中支路巡检的过程耗时大,从而不能及时检测到故障支路的问题。本发明实施例的直流电源系统绝缘监测方法包括:在确定母线发生故障时,确定与发生故障的母线连接的支路的待检测极;其中,与支路的待检测极连接的母线的绝缘电阻值不大于第一阈值;对支路的待检测极进行检测。本发明实施例在母线发生故障时,通过确定与发生故障的母线连接的支路的待检测极,并对该支路的待检测极进行检测以确定故障支路,避免了每次在母线故障时,均需对各支路的正极和负极都进行巡检,从而大大缩短了检测故障支路的时间。 The DC bridge method is not affected by distributed capacitance and has high detection sensitivity, so it is widely used by computer insulation detectors. Chinese invention patent application "A DC Power System Insulation Monitoring Method and Its Equipment" (invention patent application number: 201310063104.2 publication number: CN103018614A) discloses a DC power system insulation monitoring method and its equipment, which are used to solve the problems in the prior art In the monitoring of the existing DC power supply system, the branch circuit inspection process takes a long time, so that the problem of the faulty branch circuit cannot be detected in time. The insulation monitoring method of the DC power supply system in the embodiment of the present invention includes: when determining that the bus bar fails, determining the pole to be detected of the branch connected to the failed bus; wherein, the insulation resistance of the bus connected to the pole to be detected of the branch The value is not greater than the first threshold; detect the pole to be detected of the branch. In the embodiment of the present invention, when the bus fails, by determining the pole to be detected of the branch connected to the failed bus, and detecting the pole to be detected of the branch to determine the faulty branch, avoiding the failure of the bus every time At the same time, it is necessary to inspect the positive and negative poles of each branch, thus greatly shortening the time for detecting faulty branches.

但是,上述技术方案均未涉及变电站直流接地巡检的选线校核,缺乏对多支路绝缘下降信息的校核,无法排除干扰信息,判别时可能发生误选或漏选。 However, none of the above-mentioned technical solutions involves the line selection check of DC grounding inspection of substations, lacks the check of multi-branch insulation drop information, and cannot exclude interference information, and misselection or omission may occur during discrimination.

发明内容 Contents of the invention

本发明的目的是提供一种变电站直流接地巡检的选线校核方法,充分利用平衡电桥模式和不平衡电桥模式计算接地电阻的优点,根据故障前、后电流电压的状态量和接地电阻的计算量,以及三者的电气联系,进行故障特征辨识,识别零漂支路和接地支路,采用归谬法对接地电阻计算过程进行校核,在克服接地故障误选、漏选的同时,提高故障支路的查找速度。 The purpose of the present invention is to provide a line selection check method for substation DC grounding inspection, fully utilize the advantages of balanced bridge mode and unbalanced bridge mode to calculate grounding resistance, according to the state quantity of current and voltage before and after the fault and grounding The calculation amount of the resistance and the electrical connection of the three are used to identify the fault characteristics, identify the zero-drift branch and the grounding branch, and use the reductive method to check the calculation process of the grounding resistance. At the same time, the search speed of the faulty branch is improved.

本发明解决上述技术问题所采用的技术方案是: The technical solution adopted by the present invention to solve the problems of the technologies described above is:

一种变电站直流接地巡检的选线校核方法,用于变电站直流电源系统对地绝缘在线监测装置,其特征在于包括以下步骤: A line selection and verification method for substation DC grounding inspection, which is used in an on-line monitoring device for ground insulation of a substation DC power supply system, and is characterized in that it includes the following steps:

S100:采用不平衡电桥模式检测计算母线接地电阻; S100: Use the unbalanced bridge mode to detect and calculate the busbar grounding resistance;

S200:采用平衡电桥模式进行支路接地巡检; S200: Use the balanced bridge mode to perform branch grounding inspections;

S220:判断漏电电流是否变化,若漏电电流无变化,判定该支路有零漂无故障;否则,顺序执行步骤S240; S220: Determine whether the leakage current changes, if the leakage current does not change, determine that the branch has zero drift and no fault; otherwise, execute step S240 in sequence;

S240:判断漏电电流是否单调变化,若漏电电流不是单调变化,启动不平衡电桥模式;否则,顺序执行步骤S260; S240: Determine whether the leakage current changes monotonously, if the leakage current does not change monotonically, start the unbalanced bridge mode; otherwise, execute step S260 in sequence;

S260:故障后电流减去故障前电流,再计算接地电阻,判断是否满足支路故障判据,若满足支路故障判据,判定该支路为故障支路;否则,启动不平衡电桥模式。 S260: The current after the fault minus the current before the fault, and then calculate the grounding resistance, and judge whether the branch fault criterion is met. If the branch fault criterion is met, it is judged that the branch is a faulty branch; otherwise, start the unbalanced bridge mode .

本发明的变电站直流接地巡检的选线校核方法的一种较佳的技术方案,其特征在于还包括以下采用归谬法进行校核的步骤: A preferred technical scheme of the line selection checking method for substation DC grounding inspection of the present invention is characterized in that it also includes the following steps of checking by reductive method:

S270:根据直流接地巡检选线过程中求得的母线接地电阻,反向推算正、负母线电压的推算值; S270: According to the grounding resistance of the bus bar obtained during the line selection process of the DC grounding inspection, reversely calculate the estimated values of the positive and negative bus bar voltages;

S272:将推算所得正、负母线电压推算值,与对应的正、负母线电压实测值进行比较,若正、负母线电压推算值之中的任一项不同于其实测值,则判定选线过程中存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。 S272: Compare the estimated positive and negative bus voltages with the corresponding measured positive and negative bus voltages, and if any of the estimated positive and negative bus voltages is different from the measured value, determine the line selection In the process, there is a special situation that the bridge method cannot be accurately calculated, and the online monitoring device sends out a warning message that the line selection result is wrong.

本发明的变电站直流接地巡检的选线校核方法的一种更好的技术方案,其特征在于在所述的步骤S272之后还包括以下步骤: A better technical solution of the line selection and verification method for substation DC grounding inspection of the present invention is characterized in that it also includes the following steps after the step S272:

S274:根据选线过程中求得的各支路的正、负母线对地电阻,计算负母线和正母线对地总电阻; S274: Calculate the total resistance of the negative bus and the positive bus to ground according to the positive and negative bus-to-ground resistances of each branch obtained in the line selection process;

S276:根据负母线和正母线对地总电阻,反向推算正、负母线电压的推算值: S276: According to the total resistance of the negative busbar and positive busbar to ground, reversely calculate the estimated value of the positive and negative busbar voltage:

S278:将推算所得正、负母线电压推算值,与对应的正、负母线电压实测值进行比较,若正、负母线电压推算值之中的任一项不同于其实测值,则判定选线过程中求得的支路中,至少有一路存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。 S278: Compare the estimated values of the positive and negative bus voltages with the corresponding measured values of the positive and negative bus voltages. If any of the estimated values of the positive and negative bus voltages is different from its measured value, determine the line selection Among the branches obtained in the process, at least one of the branches has a special situation that the bridge method cannot be accurately calculated, and the online monitoring device sends out a warning message that the result of the line selection is wrong.

本发明的有益效果是: The beneficial effects of the present invention are:

本发明的变电站直流接地巡检的选线校核方法,根据故障前、后电流电压的状态量和接地电阻的计算量,以及三者的电气联系,进行故障特征辨识,采用基于逻辑事件驱动的自动巡检模式,可以有效兼顾平衡电桥的快速性和不平衡电桥的容错性,提高查找速度和容错水平,实现快速诊断并排除故障,既提高了工程现场的工作效率,又降低了盲目拉路所带来的风险。 The line selection and verification method for substation DC grounding inspection of the present invention, according to the state quantity of current and voltage before and after the fault, the calculation amount of grounding resistance, and the electrical connection of the three, carries out fault feature identification, and adopts a method based on logic event drive The automatic inspection mode can effectively take into account the rapidity of the balanced bridge and the fault tolerance of the unbalanced bridge, improve the search speed and fault tolerance level, and realize rapid diagnosis and troubleshooting, which not only improves the work efficiency of the engineering site, but also reduces blindness. The risks posed by pulling the way.

本发明的变电站直流接地巡检的选线校核方法的实用性强,只需将选线校核功能集成到变电站直流接地巡检装置中,通过逻辑判断动态调用不平衡电桥模式来辨识零漂和故障支路,相对于现有的定时调用不平衡电桥模式的自动巡检模式,可以快速识别直流接地巡检装置的误选或漏选,在不增加硬件成本的前提下提高巡检装置的性能。 The line selection and checking method for substation DC grounding inspection of the present invention has strong practicability. It only needs to integrate the line selection and checking function into the substation DC grounding inspection device, and dynamically call the unbalanced bridge mode through logical judgment to identify zero. Drift and fault branch, compared with the existing automatic inspection mode that calls the unbalanced bridge mode at regular intervals, it can quickly identify the misselection or missing selection of the DC ground inspection device, and improve the inspection without increasing hardware costs. performance of the device.

附图说明 Description of drawings

图1是母线接地电阻的不平衡电桥模式检测原理图; Figure 1 is a schematic diagram of the unbalanced bridge mode detection of the bus grounding resistance;

图2是K1闭合状态的母线绝缘电阻测量电路图; Figure 2 is a circuit diagram for measuring the busbar insulation resistance in the closed state of K1;

图3是K2闭合状态的母线绝缘电阻测量电路图; Fig. 3 is a circuit diagram for measuring the busbar insulation resistance in the closed state of K2;

图4是直流检测法支路检测原理图; Fig. 4 is the schematic diagram of branch circuit detection of DC detection method;

图5是基于平衡电桥模式的单支路接地等效电路图; Fig. 5 is an equivalent circuit diagram of a single branch grounding based on a balanced bridge mode;

图6是基于不平衡电桥模式的单支路接地等效电路图; Fig. 6 is the equivalent circuit diagram of single branch grounding based on unbalanced bridge mode;

图7是基于逻辑事件驱动的自动巡检模式的控制流程图; Fig. 7 is the control flowchart of the automatic inspection mode driven based on logical events;

图8是多支路接地的等效电路图; Fig. 8 is the equivalent circuit diagram of multi-branch grounding;

图9是变电站直流电源系统对地绝缘在线监测装置的结构示意图。 Fig. 9 is a schematic structural diagram of an on-line monitoring device for ground insulation of a substation DC power supply system.

具体实施方式 detailed description

为了能更好地理解本发明的上述技术方案,下面结合附图和实施例进行进一步地详细描述。 In order to better understand the above technical solutions of the present invention, a further detailed description will be given below in conjunction with the drawings and embodiments.

本发明的变电站直流接地巡检的选线校核方法,用于变电站直流电源系统对地绝缘在线监测装置,所述的变电站直流电源系统包括正母线+KM和负母线-KM,以及连接常规负荷、继电保护及自动装置、远动通讯装置和事故照明装置的若干直流支路;如图1所示,所述的变电站直流电源系统还包括用于系统在线监控的一组直流电桥元件,所述的直流电桥元件包括两个阻值相同的标准电阻构成的平衡桥电阻Rb1、Rb2;两个阻值相同的标准电阻构成的测试桥电阻RL1、RL2;两个控制测试桥电阻接通状态的继电器切换开关K1、K2;以及用于对变电站直流电源系统的对地绝缘状态进行巡检的在线监测装置1,即巡检装置。如图4所示,所述的在线监测装置1的电压检测输入端,连接到变电站直流电源系统的正母线+KM和负母线-KM,所述的在线监测装置1的支路漏电流检测输入端,连接到每一条直流支路的直流漏电流传感器I1、I2(简称直流传感器或互感器),对各支路的漏电流进行采样。变电站直流电源系统对地绝缘在线监测装置1的结构如图9所示,包括在线监测自动巡检控制模块10,用于控制各功能模块的运行,执行基于逻辑事件驱动的自动巡检模式;直流母线检测模块11,用于检测计算正负直流母线对地绝缘电阻,对正母线或负母线的接地故障进行在线监测;平衡电桥检测模块12,用于检测计算支路绝缘电阻,采用平衡电桥模式查找直流接地故障支路;不平衡电桥检测模块13,通过投切测试桥电阻改变正负直流母线对地电压和支路总漏电流,检测计算各支路绝缘电阻,采用不平衡电桥模式查找直流接地故障支路;故障支路判定模块14,用于比较各支路的绝缘电阻检测结果,选择确定发生接地故障的故障支路;选线校核模块14,用于根据故障前后的电压、电流与电阻的关联逻辑进行故障特征辨识,避免故障支路的误选或漏选。 The line selection and checking method for substation DC grounding inspection of the present invention is used for the on-line monitoring device of the ground insulation of the substation DC power supply system. The substation DC power supply system includes positive busbar +KM and negative busbar-KM, and connects conventional loads , relay protection and automatic devices, telecontrol communication devices and several DC branches of emergency lighting devices; The DC bridge element described above includes two balanced bridge resistors Rb1 and Rb2 formed by standard resistors with the same resistance value; two test bridge resistors RL1 and RL2 formed by two standard resistors with the same resistance value; Relay switching switches K1, K2; and an online monitoring device 1 for patrolling the ground insulation state of the DC power system of the substation, that is, the patrolling device. As shown in Figure 4, the voltage detection input terminal of the online monitoring device 1 is connected to the positive bus +KM and the negative bus -KM of the substation DC power system, and the branch leakage current detection input of the online monitoring device 1 terminal, connected to the DC leakage current sensors I1 and I2 (referred to as DC sensors or transformers) of each DC branch, to sample the leakage current of each branch. The structure of the on-line monitoring device 1 for the ground insulation of the substation DC power supply system is shown in Figure 9, including the online monitoring automatic inspection control module 10, which is used to control the operation of each functional module and execute the automatic inspection mode driven by logic events; The busbar detection module 11 is used to detect and calculate the insulation resistance of the positive and negative DC busbars to the ground, and conduct online monitoring of the ground fault of the positive busbar or the negative busbar; the balanced bridge detection module 12 is used to detect and calculate the insulation resistance of the branch circuit, using The bridge mode searches for the DC ground fault branch; the unbalanced bridge detection module 13 changes the positive and negative DC busbars to ground voltage and the total leakage current of the branch through the switching test bridge resistance, detects and calculates the insulation resistance of each branch, and adopts the unbalanced circuit The bridge mode searches for the DC ground fault branch; the fault branch judgment module 14 is used to compare the insulation resistance detection results of each branch, and selects and determines the fault branch where the ground fault occurs; the line selection check module 14 is used to The associated logic of voltage, current and resistance is used to identify fault characteristics to avoid misselection or missed selection of fault branches.

母线接地电阻检测原理采用电桥法,其原理如图1所示。其中Up、Un为正母线和负母线电压;Rb1、Rb2为平衡桥电阻,它们是阻值相同的标准电阻,分别固定在直流母线两端;RL1、RL2为测试桥电阻,它们是阻值相同的标准电阻,通过继电器投切到直流母线上;平衡桥电阻和测试桥电阻数值的选取要考虑母线电阻的功率和漏电传感器的最大检测能力。Rx、Ry为待测接地电阻值;图中大地点电压为零电势,满足公式: The detection principle of the bus grounding resistance adopts the bridge method, and its principle is shown in Figure 1. Among them, U p and U n are positive and negative bus voltages; R b1 and R b2 are balance bridge resistors, which are standard resistors with the same resistance value and are respectively fixed at both ends of the DC bus; R L1 and R L2 are test bridge resistors , they are standard resistors with the same resistance value, switched to the DC bus through the relay; the selection of the balance bridge resistance and the test bridge resistance value should consider the power of the bus resistance and the maximum detection capability of the leakage sensor. R x and R y are the ground resistance values to be measured; the voltage at the large point in the figure is zero potential, which satisfies the formula:

Un/Rb1+Up/Rb2+Un/RL1+Up/RL2+Un/Rx+Up/Ry=0; U n /R b1 +U p /R b2 +U n /R L1 +U p /R L2 +U n /R x +U p /R y = 0;

测量时通过切换开关K1、K2的接通和关断,从而根据测量得到的Un和Up来计算出直流母线对地绝缘电阻。 During the measurement, switch the switches K1 and K2 on and off to calculate the insulation resistance of the DC bus to ground according to the measured Un and Up.

K1闭合时等效电路如图2所示。根据图2可得: The equivalent circuit when K1 is closed is shown in Figure 2. According to Figure 2, we can get:

Un1/Rb1+Up1/Rb2+Un1/RL1+Un1/Rx+Up1/Ry=0(1) U n1 /R b1 +U p1 /R b2 +U n1 /R L1 +U n1 /R x +U p1 /R y = 0(1)

K2闭合时等效电路如图3所示。从电路列出公式: The equivalent circuit when K2 is closed is shown in Figure 3. List the formula from the circuit:

Un2/Rb1+Up2/Rb2+Up2/RL2+Un2/Rx+Up2/Ry=0(2) U n2 /R b1 +U p2 /R b2 +U p2 /R L2 +U n2 /R x +U p2 /R y = 0(2)

由公式1、2联合得到Rx和Ry Rx and Ry are obtained by combining formulas 1 and 2

Rx=(Un1*Up2-Un2*Up1)/(A*Up2-B*Up1)(3) R x =(U n1 *U p2 -U n2 *U p1 )/(A*U p2 -B*U p1 )(3)

Ry=(Un2*Up1-Un1*Up2)/(A*Un2-B*Un1)(4) R y =(U n2 *U p1 -U n1 *U p2 )/(A*U n2 -B*U n1 )(4)

其中:A=-(Un1/Rb1+Up1/Rb2+Un1/RL1),B=-(Un2/Rb1+Up2/Rb2+Up2/RL2)。 Where: A=-(U n1 /R b1 +U p1 /R b2 +U n1 /R L1 ), B=-(U n2 /R b1 +U p2 /R b2 +U p2 /R L2 ).

从上式可知,影响Rx和Ry的因素为测量电压Un1,Un2,Up1,Up2和固定电阻Rb1、Rb2、RL1、RL2。所以只要考虑测量电压对接地电阻的影响即可。由于直流电压量值较大,较小的绝对值测量偏差不会引起较大的相对量变化,其测量可信度相对支路更高。 It can be seen from the above formula that the factors affecting R x and R y are the measured voltages U n1 , U n2 , U p1 , U p2 and the fixed resistances R b1 , R b2 , R L1 , and R L2 . Therefore, it is only necessary to consider the effect of the measured voltage on the ground resistance. Due to the large magnitude of the DC voltage, a small absolute value measurement deviation will not cause a large relative quantity change, and its measurement reliability is higher than that of the branch.

直流电桥法利用母线正极+KM对地电压、母线负极-KM对地电压和支路直流漏电流计算支路正负极对地绝缘接地电阻值,再结合支路绝缘报警整定值进行选线。 The DC bridge method uses the bus positive pole +KM voltage to ground, the bus negative pole -KM ground voltage and the DC leakage current of the branch to calculate the insulation grounding resistance value of the positive and negative poles of the branch to the ground, and then selects the line in combination with the insulation alarm setting value of the branch.

直流支路检测原理如图4所示,其中I1、I2对应1#支路和2#支路总漏电流。 The principle of DC branch detection is shown in Figure 4, where I1 and I2 correspond to the total leakage current of 1# branch and 2# branch.

平衡电桥测量法: Balanced bridge measurement method:

直流平衡电桥模式计算支路绝缘电阻时,首先判断支路总漏电流的方向,定位支路正极或负极绝缘降低,然后与正母线对地电压或负母线对地电压计算接地电阻值。结合图1和图4可得出单支路接地基于平衡电桥模式的等效电路如图5所示,其中I0为支路总漏电电流,图中所示方向为参考方向。根据图5可求得正负母线对地电阻值: When calculating the insulation resistance of a branch in the DC balance bridge mode, first determine the direction of the total leakage current of the branch, locate the positive or negative insulation of the branch, and then calculate the grounding resistance value with the positive bus-to-ground voltage or the negative bus-to-ground voltage. Combining Figure 1 and Figure 4, it can be concluded that the equivalent circuit of single-branch grounding based on balanced bridge mode is shown in Figure 5, where I 0 is the total leakage current of the branch, and the direction shown in the figure is the reference direction. According to Figure 5, the resistance value of positive and negative bus bars to ground can be obtained:

I0为负:正母线对地电阻值为无穷大, I 0 is negative: the resistance value of the positive busbar to ground is infinite,

负母线对地电阻值Rn=Un/I0(5), Negative busbar resistance to ground R n =U n /I 0 (5),

I0为正:正母线对地电阻值Rp=Up/I0(6), I 0 is positive: positive busbar resistance to ground R p = U p /I 0 (6),

负母线对地电阻值为无穷大。 The resistance value of the negative busbar to ground is infinite.

不平衡电桥测量法: Unbalanced bridge measurement method:

直流不平衡电桥模式计算支路绝缘电阻时,同样使用正母线对地电压、负母线对地电压、支路直流总漏电流测量计算,但需要通过投切测试桥电阻改变正母线对地电压、负母线对地电压和支路总漏电流。 When calculating the branch insulation resistance in the DC unbalanced bridge mode, the positive bus-to-ground voltage, negative bus-to-ground voltage, and branch DC total leakage current are also used for calculation, but the positive bus-to-ground voltage needs to be changed by switching the test bridge resistance , Negative bus-to-ground voltage and branch total leakage current.

闭合K2(投入RL2)时,支路等效电路如图6(a)所示,此时Up、Un、I0分别取值Up1、Un1、I1。闭合K1(投入RL1)时,支路等效电路如图6(b)所示,此时Up、Un、I0分别取值Up2、Un2、I2。电流流出节点A为正方向,Ry和Rx分别为某支路的正母线对地绝缘电阻值和负母线对地绝缘电阻值。 When closing K2 (turning on R L2 ), the equivalent circuit of the branch circuit is shown in Fig. 6(a). At this time, U p , U n , and I 0 take values U p1 , U n1 , and I 1 , respectively. When closing K1 (turning on R L1 ), the branch equivalent circuit is shown in Fig. 6(b). At this time, U p , U n , and I 0 take values U p2 , U n2 , and I 2 , respectively. The current flowing out of node A is the positive direction, and Ry and Rx are the positive busbar-to-ground insulation resistance value and the negative busbar-to-ground insulation resistance value of a certain branch respectively.

根据图6(a)可得: According to Figure 6(a), we can get:

I1-Un1/Rx-Up1/Ry=0(7) I 1 −U n1 /R x −U p1 /R y =0(7)

根据图6(b)可得: According to Figure 6(b), we can get:

I2-Un2/Rx-Up2/Ry=0(8) I 2 −U n2 /R x −U p2 /R y =0(8)

联合式(7)和式(8)求解得: Combined formula (7) and formula (8) to solve:

Rx=(Up1Un2-Up2Un1)/(Up1I2-Up2I1)(9) R x =(U p1 U n2 -U p2 U n1 )/(U p1 I 2 -U p2 I 1 )(9)

Ry=(Up2Un1-Up1Un2)/(Un1I2-Un2I1)(10) R y =(U p2 U n1 -U p1 U n2 )/(U n1 I 2 -U n2 I 1 )(10)

如果Ry为无穷大,即负母线单极对地绝缘降低,通过(7)和(8)公式简化公式: If R y is infinite, that is, the negative bus unipolar-to-ground insulation is reduced, the formulas are simplified by formulas (7) and (8):

Rx=(Un2-Un1)/(I2-I1)(11) R x =(U n2 -U n1 )/(I 2 -I 1 )(11)

如果Rx为无穷大,即正母线单极对地绝缘降低,通过(7)和(8)公式简化公式: If R x is infinite, that is, the unipolar-to-ground insulation of the positive busbar is reduced, the formulas are simplified by the formulas (7) and (8):

Ry=(Up2-Up1)/(I2-I1)(12) R y =(U p2 -U p1 )/(I 2 -I 1 )(12)

当某极接地时,根据公式11和12会误报另外一极也存在相同的接地电阻。 When one pole is grounded, according to formulas 11 and 12, it will be falsely reported that the other pole also has the same grounding resistance.

直流漏电流传感器(互感器)为非接触式传感,依靠磁感线圈感应测试,测量对象信号微小,容易受外界干拢(如地磁干扰,互感器放置不同,零点漂移也不同);直流漏电流传感器磁线圈剩磁;直流漏电流传感器检测电路如运放等的漂移(温漂、时漂等)均为直流,长时间运行后,使电流传感器存在零漂问题,所以根据公式9和10计算支路绝缘接地电阻值,容易产生误报支路。以下通过实施例分析选线误报或漏报的状态,详细说明本发明的变电站直流接地巡检的选线校核方法: The DC leakage current sensor (transformer) is a non-contact sensor, relying on the magnetic induction coil induction test, the signal of the measurement object is small, and it is easy to be interfered by the outside world (such as geomagnetic interference, the zero point drift is different if the transformer is placed differently); The residual magnetism of the magnetic coil of the current sensor; the drift (temperature drift, time drift, etc.) of the DC leakage current sensor detection circuit such as an operational amplifier is all DC. Calculating the insulation and grounding resistance value of the branch circuit is prone to false reporting of the branch circuit. In the following, the status of misreporting or missing reporting of line selection is analyzed through the embodiments, and the line selection checking method of the substation DC grounding inspection of the present invention is described in detail:

(1)直流漏电流传感器零漂对计算支路接地电阻的影响。如图4在实际220V系统时,不投切测试桥电阻下测量Up、Un分别为176V、-44V,平衡法计算支路接地电阻如下: (1) The influence of the zero drift of the DC leakage current sensor on the calculation of the branch grounding resistance. As shown in Figure 4, in the actual 220V system, when the test bridge resistance is not switched, U p and U n are measured as 176V and -44V respectively, and the grounding resistance of the branch circuit is calculated by the balance method as follows:

1#支路零漂I10=2mA;Ry1=176/2=88KΩ 1# branch zero drift I 10 =2mA; R y1 =176/2=88KΩ

1#支路零漂I10=-2mA;Rx1=-44/(-2)=22KΩ 1# branch zero drift I 10 =-2mA; R x1 =-44/(-2)=22KΩ

2#支路零漂I20=-2mA,即实测为-6.4mA,Rx2=6.875KΩ 2# branch zero drift I 20 =-2mA, that is, the actual measurement is -6.4mA, R x2 =6.875KΩ

不平衡电桥模式通过差分量消除零漂影响。 The unbalanced bridge mode eliminates the effect of zero drift through the differential component.

(2)直流漏电流传感器中的磁线圈剩磁、信号干扰、采样电路不稳定出现测量电流跳变。例如某电站长年运行下某支路直流漏电流传感器检测实际直流漏电流有0.5mA的值跳变,同时支路绝缘电阻还没有达到报警值。以图4定为220V系统(支路绝缘报警为50KΩ)为例分析如下: (2) The residual magnetism of the magnetic coil in the DC leakage current sensor, signal interference, and instability of the sampling circuit cause a jump in the measurement current. For example, when a power station has been in operation for many years, the DC leakage current sensor of a certain branch detects that the actual DC leakage current has a value jump of 0.5mA, and the insulation resistance of the branch has not yet reached the alarm value. Taking Figure 4 as an example of a 220V system (branch insulation alarm is 50KΩ) as an example, the analysis is as follows:

1#支路的负母线对地绝缘降低为60K,此时Up、Un分别为180V、-40V,I1可能为-0.667mA、-1.167mA;即负母线对地绝缘电阻值对应为60KΩ和34KΩ,而2#支路负母线对地有一个10KΩ电阻,直接报警,可能同时带出1#支路的绝缘降低。 The insulation resistance of the negative busbar of the 1# branch to the ground is reduced to 60K. At this time, U p and U n are 180V and -40V respectively, and I 1 may be -0.667mA and -1.167mA; that is, the insulation resistance value of the negative busbar to the ground corresponds to 60KΩ and 34KΩ, and the 2# branch negative bus has a 10KΩ resistance to the ground, which will directly alarm and may bring out the insulation reduction of the 1# branch at the same time.

相同的条件,使用不平衡电桥推算,由于1#支路直流漏电流传感器的采样值跳变而误选,多选出1#支路。 Under the same conditions, use the unbalanced bridge to calculate, because the sampling value of the DC leakage current sensor of the 1# branch jumps and is wrongly selected, the 1# branch is selected more.

通过以上两点分析,直流漏电流传感器采样零漂可以通过不平衡电桥模式解决,但对于常见的直流漏电流传感器采样跳变,即使是不平衡电桥模式也无法解决。此外,平衡电桥模式还不能检测正负母线绝缘电阻同时下降的情况,即存在动作死区问题。 Through the analysis of the above two points, the sampling zero drift of the DC leakage current sensor can be solved by the unbalanced bridge mode, but for the common DC leakage current sensor sampling jump, even the unbalanced bridge mode cannot solve it. In addition, the balanced bridge mode cannot detect the situation that the insulation resistance of the positive and negative busbars drops at the same time, that is, there is an action dead zone problem.

故障支路的特征分析: Characteristic analysis of the fault branch:

直流母线接地电阻计算精度高于支路,其优先级为最高。 The calculation accuracy of the DC bus grounding resistance is higher than that of the branch circuit, and its priority is the highest.

在计算接地故障后进行选线时,不仅考虑接地电阻的绝对值,还要考虑故障前后电流电压等状态量的相对变化量——电压电流变化方向和变化大小符合真实接地。即根据电压大小和漏电电流大小的连续变化,分析电阻与电压、电流的关联逻辑来校核。通过电路推导,可得出如下特征: When calculating the line selection after the ground fault, not only the absolute value of the ground resistance is considered, but also the relative change of the current and voltage before and after the fault. The direction and magnitude of the change of the voltage and current conform to the real ground. That is, according to the continuous change of voltage and leakage current, analyze the correlation logic of resistance, voltage and current to check. Through circuit derivation, the following characteristics can be obtained:

(1)当某支路存在零漂电流或采样电流跳变时,即故障前零漂电流为漏电电流,故障前后漏电电流不变,其接地电阻和电压成线性变化,因为电压降低可能导致接地电阻变小而满足接地电阻门槛值,但应排除该支路为故障支路。 (1) When there is zero drift current or sampling current jump in a certain branch, that is, the zero drift current before the fault is the leakage current, the leakage current remains unchanged before and after the fault, and its grounding resistance and voltage change linearly, because the voltage drop may cause grounding The resistance becomes smaller and meets the ground resistance threshold, but the branch should be ruled out as a faulty branch.

(2)绝缘较低的支路,存在较小漏电电流,其他支路接地时,电压降低,但相应本支路电流也减小,不会误选。 (2) The branch with lower insulation has a small leakage current. When other branches are grounded, the voltage decreases, but the current of this branch also decreases correspondingly, so it will not be selected by mistake.

(3)没有零漂的支路存在接地故障时,漏电电流增大,对地电压降低,接地电阻随着电压加速变化。 (3) When there is a ground fault in the branch without zero drift, the leakage current increases, the voltage to ground decreases, and the ground resistance changes with the acceleration of the voltage.

(4)当某支路存在漏电电流时,故障前后漏电电流单调递增,则故障前后为同极绝缘下降,但存在误选的可能性。 (4) When there is a leakage current in a certain branch, the leakage current increases monotonously before and after the fault, and the insulation of the same pole before and after the fault decreases, but there is a possibility of misselection.

(5)当某支路存在漏电电流时,故障前后漏电电流非单调递增,则需要分析故障前存在漏电一极在故障后的接地电阻变化情况来分析漏电电流是否是零漂。如果不是零漂,则是该支路另一极发生接地。如果是零漂,则需要做差流,避免漏选。 (5) When there is a leakage current in a certain branch, the leakage current increases non-monotonically before and after the fault, and it is necessary to analyze the grounding resistance change of a pole with leakage before the fault and after the fault to analyze whether the leakage current is zero drift. If it is not zero drift, the other pole of the branch is grounded. If it is zero drift, you need to make differential current to avoid missing selection.

(6)对于正负母线绝缘电阻同时下降的情况,在目前的时间辨识度下,是能够区分两极接地的先后顺序的。其在平衡模式下的相应特征是,先报某一极接地,然后又不报故障接地。此时就需要切换至不平衡模式下查找接地电阻,避免漏选。 (6) For the case where the insulation resistance of the positive and negative busbars decreases at the same time, under the current time recognition, it is possible to distinguish the sequence of the grounding of the two poles. Its corresponding feature in the balanced mode is that a certain pole is reported to be grounded first, and then the fault ground is not reported. At this time, it is necessary to switch to the unbalanced mode to find the grounding resistance to avoid missing the selection.

正常情况下,是无法区分(1)和(2)的小漏电电流是因为零漂还是因为绝缘降低导致的。所以不能根据支路存在漏电电流来判断该支路发生零漂。 Under normal circumstances, it is impossible to distinguish whether the small leakage currents of (1) and (2) are caused by zero drift or insulation degradation. Therefore, it cannot be judged that the branch has zero drift based on the leakage current in the branch.

通过以上分析,本发明根据故障前、后电流电压的状态量和接地电阻的计算量,以及三者的电气联系,进行故障特征辨识,提出了基于逻辑事件驱动的自动巡检模式。本发明的变电站直流接地巡检的选线校核方法的一个实施例如图7所示,包括以下步骤: Through the above analysis, the present invention conducts fault feature identification based on the state quantity of current and voltage before and after the fault, the calculation amount of grounding resistance, and the electrical connection between the three, and proposes an automatic inspection mode driven by logic events. An embodiment of the line selection and checking method of substation DC grounding inspection of the present invention is shown in Figure 7, including the following steps:

S100:采用不平衡电桥模式检测计算母线接地电阻; S100: Use the unbalanced bridge mode to detect and calculate the busbar grounding resistance;

S200:采用平衡电桥模式进行支路接地巡检; S200: Use the balanced bridge mode to perform branch grounding inspections;

S220:判断漏电电流是否变化,若漏电电流无变化,判定该支路有零漂无故障;否则,顺序执行步骤S240; S220: Determine whether the leakage current changes, if the leakage current does not change, determine that the branch has zero drift and no fault; otherwise, execute step S240 in sequence;

S240:判断漏电电流是否单调变化,若漏电电流不是单调变化,启动不平衡电桥模式;否则,顺序执行步骤S260; S240: Determine whether the leakage current changes monotonously, if the leakage current does not change monotonically, start the unbalanced bridge mode; otherwise, execute step S260 in sequence;

S260:故障后电流减去故障前电流,再计算接地电阻,判断是否满足支路故障判据,若满足支路故障判据,判定该支路为故障支路;否则,启动不平衡电桥模式。 S260: The current after the fault minus the current before the fault, and then calculate the grounding resistance, and judge whether the branch fault criterion is met. If the branch fault criterion is met, it is judged that the branch is a faulty branch; otherwise, start the unbalanced bridge mode .

基于归谬法校核: Checking based on reductio absurdum:

根据电桥法的容错能力数学上分析可知: According to the mathematical analysis of the fault tolerance ability of the bridge method, it can be known that:

1)平衡电桥模式相当于根已知2个变量,据1个方程式(5)或式(6),求解1个未知量。当2个已知量只要有1个出错,则求解结果错误,根据单一时间断面的数据无法容错。 1) The balanced bridge mode is equivalent to solving one unknown quantity according to one equation (5) or (6) based on two known variables. When only one of the two known quantities is wrong, the solution result will be wrong, and the data of a single time section cannot be fault-tolerant.

2)不平衡电桥模式相当于已知6个已知量,根据2个方程式(7)和式(8),求解2个未知量。当其中1个未知量为无穷大(单极接地时),相当于减少了1个未知量;此时若出现零漂,相当于增加1个新的未知量,此时又变成求解2个未知量,还是有解的。但若出现两极接地,同时又有零漂时,相当于2个方程求解3个未知量,不平衡电桥模式无解。 2) The unbalanced bridge mode is equivalent to knowing 6 known quantities, and solving 2 unknown quantities according to 2 equations (7) and (8). When one of the unknown quantities is infinite (unipolar grounding), it is equivalent to reducing one unknown quantity; if zero drift occurs at this time, it is equivalent to adding a new unknown quantity, and at this time it becomes to solve two unknown quantities Quantity, there is still a solution. However, if both poles are grounded and there is zero drift at the same time, it is equivalent to solving 3 unknown quantities with 2 equations, and the unbalanced bridge mode has no solution.

根据本发明的变电站直流接地巡检的选线校核方法的一个实施例,还包括以下采用归谬法进行校核的步骤: According to an embodiment of the line selection checking method of substation DC grounding inspection of the present invention, it also includes the following steps of checking by reductive method:

S270:根据直流接地巡检选线过程中求得的母线接地电阻Rx和Ry,反向推算正、负母线电压的推算值U'p和U'nS270: According to the busbar grounding resistance Rx and Ry obtained during the DC grounding inspection line selection process, reversely calculate the estimated values U'p and U'n of the positive and negative busbar voltages;

S272:将推算所得正、负母线电压推算值U'p和U'n,与对应的正、负母线电压实测值Up和Un进行比较,若U'p和U'n之中的任一项不同于其实测值,则判定选线过程中求得的支路中存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。 S272: Compare the calculated positive and negative bus voltage values U' p and U' n with the corresponding positive and negative bus voltage measured values U p and U n , if any of U' p and U' n If one is different from its measured value, it is determined that there is a special situation that the bridge method cannot be accurately calculated in the branch obtained during the line selection process, and the online monitoring device sends a warning message that the line selection result is wrong.

根据本发明的变电站直流接地巡检的选线校核方法的一个优选实施例,在所述的步骤S272之后还包括以下步骤: According to a preferred embodiment of the line selection and verification method for substation DC grounding inspection of the present invention, the following steps are also included after the step S272:

S274:根据选线过程中求得的支路i的正、负母线对地电阻Ryi和Rxi,计算负母线对地总电阻R=Rx1//Rx2....Rxm//Rb1,正母线对地总电阻R=Ry1//Ry2....Rym//Rb2,其中,i为从1到m的整数,m为变电站直流电源系统总的支路数; S274 : Calculate the total resistance of the negative bus to ground R xΣ = R x1 //R x2 ....R xm / /R b1 , the total resistance of the positive bus bar to ground R = R y1 //R y2 ....R ym //R b2 , where i is an integer from 1 to m, and m is the total support of the DC power system of the substation Road number;

S276:根据负母线对地总电阻R和正母线对地总电阻R,反向推算正、负母线电压的推算值U"p和U"nS276: According to the total resistance R xΣ of the negative bus to ground and the total resistance R of the positive bus to ground , reversely calculate the estimated values U" p and U" n of the positive and negative bus voltages:

U″p=U*R/(R+R)(13) U″ p = U*R /(R +R )(13)

U"n=-U*R/(R+R)(14) U" n =-U*R /(R +R )(14)

其中,U"p为正母线电压的推算值,U"n为负母线电压的推算值,U为直流母线电压,R为负母线对地总电阻,R为正母线对地总电阻; Among them, U" p is the estimated value of the positive bus voltage, U" n is the estimated value of the negative bus voltage, U is the DC bus voltage, R is the total resistance of the negative bus to ground, and R is the total resistance of the positive bus to ground;

S278:将推算所得正、负母线电压推算值U"p和U"n,与对应的正、负母线电压实测值Up和Un进行比较,若U"p和U"n之中的任一项不同于其实测值,则判定选线过程中求得的m条支路中,至少有一路存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。 S278: Comparing the calculated values U" p and U" n of the positive and negative bus voltages with the corresponding measured values U p and U n of the positive and negative bus voltages, if any of U" p and U" n If one is different from its measured value, it is determined that among the m branches obtained in the line selection process, there is at least one special case where the bridge method cannot be accurately calculated, and the online monitoring device sends an error message that the line selection result is incorrect. warning message.

采用归谬法进行校核的原理,首先假定所有支路接地电阻计算值为真,然后由计算出的接地电阻推算参与多接地支路的正、负母线电压的推算值U'p、U'n、U"p和U"n。若计算出值U'p、U'n、U"p和U"n与实测值Up和Un不同,则说明电桥法未能正确处理零漂电流。从式(13)和式(14)可知,m个支路中的任何一个支路的接地电阻计算错误,都将导致计算的母线电压与实测的母线电压不同,从而说明这些支路中存在平衡电桥模式或不平衡电桥模式无法准确计算的特殊情况,需要进一步采用其他方法对选线结果进行人工干预。 The principle of checking by reductio ad absurdis first assumes that the calculated value of grounding resistance of all branches is true, and then calculates the estimated values U' p , U' of the positive and negative bus voltages participating in multiple grounding branches from the calculated grounding resistance n , U" p , and U" n . If the calculated values U' p , U' n , U" p and U" n are different from the measured values U p and U n , it means that the bridge method cannot correctly handle the zero drift current. From formula (13) and formula (14), it can be seen that the calculation error of the grounding resistance of any one of the m branches will cause the calculated bus voltage to be different from the measured bus voltage, thus indicating that there is a balance in these branches In special cases where the bridge mode or unbalanced bridge mode cannot be accurately calculated, other methods need to be further used to manually intervene in the line selection results.

实施例效果分析 Embodiment effect analysis

对上海某变电站2006年建成运行中的直流220V系统监测分析,实际电压243.5V,使用深圳奥特迅电力设备的微机绝缘监测仪WJY3000A,直流电源系统分出48路馈出回路。选出4路支路进行分析,选择支路分别为: The monitoring and analysis of a DC 220V system in a substation in Shanghai that was built and operated in 2006 shows that the actual voltage is 243.5V, using the microcomputer insulation monitor WJY3000A of Shenzhen Aotexun Power Equipment, and the DC power system has 48 feed-out circuits. Select 4 branches for analysis, and the selected branches are:

1#支路直流采样回路正常,无零漂,采样结果稳定性好,绝缘性好; The 1# branch DC sampling circuit is normal, without zero drift, the sampling result is stable, and the insulation is good;

4#支路直流采样回路正常,无零漂,采样结果稳定性好,负母线绝缘电阻值降低; The 4# branch DC sampling circuit is normal, without zero drift, the sampling result is stable, and the insulation resistance value of the negative busbar is reduced;

17#路直流采样回路正常,有零漂,采样结果稳定性好,负母线绝缘电阻值降低; The DC sampling circuit of 17# is normal, with zero drift, the sampling result is stable, and the insulation resistance value of the negative busbar is reduced;

33#路直流采样回路正常,无零漂,采样结果稳定性跳变大,负母线绝缘电阻值降低。 The 33# DC sampling circuit is normal, without zero drift, the stability of the sampling result jumps greatly, and the insulation resistance value of the negative busbar decreases.

采用选线校核机制,对现场系统进行数据记录如表1至表3所示,表4和表5为定检实验数据,其中,表4为1#支路负母线对地接10K电阻负载的实验数据,表5为1#支路负母线直接接地的实验数据。在表1~表5中:RBp和RBn分别为平衡桥法计算正对地和负对地电阻值,RNp和RNn分别为不平衡桥法计算正对地和负对地电阻值,单位KΩ。 Using the line selection check mechanism, the data records of the on-site system are shown in Table 1 to Table 3. Table 4 and Table 5 are the test data of regular inspection. Among them, Table 4 shows that the negative busbar of the 1# branch is connected to the ground with a 10K resistance load Table 5 is the experimental data of the direct grounding of the negative busbar of the 1# branch. In Tables 1 to 5: R Bp and R Bn are the positive-to-ground and negative-to-ground resistance values calculated by the balanced bridge method, and R Np and R Nn are the positive-to-ground and negative-to-ground resistance values calculated by the unbalanced bridge method. , unit KΩ.

表12014年6月10日记录数据 Table 1 Record data on June 10, 2014

表22014年7月11日记录数据 Table 2 Record data on July 11, 2014

表32014年8月10日记录数据 Table 3 Recorded data on August 10, 2014

表42014年9月10日记录数据(定检试验1#负接10K) Table 4 Recorded data on September 10, 2014 (regular inspection test 1# negative connection 10K)

表52014年9月10日记录数据(定检试验1#负母线直接接地实验) Table 5 Recorded data on September 10, 2014 (regular inspection test 1# negative busbar direct grounding experiment)

通过表1~表5实验数据分析,表4数据选线为1#和33#,由于33#的直流传感器采样不稳定造成多选;表5与表4同样的结果。 Through the analysis of the experimental data in Tables 1 to 5, the data in Table 4 are selected as 1# and 33#, and the sampling of the DC sensor of 33# is unstable, resulting in multiple selections; Table 5 and Table 4 have the same results.

使用选线校核机制结合表1~表5的数据,由于4#、17#、33#支路已经存在绝缘降低,使用数学统计算法分析变化趋势,变化率大的为优先提示信息。所以对表4提示1#支路为优先排查的支路;而同样分析表5,1#支路也是优先排查的支路。而本发明的选线校核方法对故障前后的数据分析和逻辑推导,可分析找出CT零漂大的直流传感器17#。基于本发明的选线校核方法对故障后的数据分析和推导,可挑选出33#支路存在采样跳变。校核完成后,形成相应的校核报告,告知运维人员17#存在零漂,33#存在采样跳变。 Using the line selection check mechanism combined with the data in Tables 1 to 5, since the 4#, 17#, and 33# branches have insulation degradation, use mathematical statistical algorithms to analyze the change trend, and the one with the largest change rate is the priority prompt information. Therefore, it is indicated in Table 4 that the 1# branch is the branch to be checked first; while analyzing Table 5, the 1# branch is also the branch to be checked first. However, the line selection and checking method of the present invention can analyze and find out the DC sensor 17# with large CT zero drift through data analysis and logical derivation before and after the fault. Based on the analysis and derivation of the data after the fault based on the line selection and verification method of the present invention, it is possible to select the sampling jump in the 33# branch. After the calibration is completed, a corresponding calibration report is formed to inform the operation and maintenance personnel that 17# has zero drift and 33# has a sampling jump.

本技术领域中的普通技术人员应当认识到,以上的实施例仅是用来说明本发明的技术方案,而并非用作为对本发明的限定,任何基于本发明的实质精神对以上所述实施例所作的变化、变型,都将落在本发明的权利要求的保护范围内。 Those of ordinary skill in the technical field should recognize that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not used as limitations to the present invention. All changes and modifications will fall within the protection scope of the claims of the present invention.

Claims (3)

1.一种变电站直流接地巡检的选线校核方法,用于变电站直流电源系统对地绝缘在线监测装置,其特征在于包括以下步骤:1. A line selection check method for transformer substation DC grounding inspection, used for transformer substation DC power system to ground insulation on-line monitoring device, it is characterized in that comprising the following steps: S100:采用不平衡电桥模式检测计算母线接地电阻;S100: Use the unbalanced bridge mode to detect and calculate the busbar grounding resistance; S200:采用平衡电桥模式进行支路接地巡检;S200: Use the balanced bridge mode to perform branch grounding inspections; S220:判断漏电电流是否变化,若漏电电流无变化,判定该支路有零漂无故障;否则,顺序执行步骤S240;S220: Determine whether the leakage current changes, if the leakage current does not change, determine that the branch has zero drift and no fault; otherwise, execute step S240 in sequence; S240:判断漏电电流是否单调变化,若漏电电流不是单调变化,启动不平衡电桥模式;否则,顺序执行步骤S260;S240: Determine whether the leakage current changes monotonously, if the leakage current does not change monotonically, start the unbalanced bridge mode; otherwise, execute step S260 in sequence; S260:故障后电流减去故障前电流,再计算接地电阻,判断是否满足支路故障判据,若满足支路故障判据,判定该支路为故障支路;否则,启动不平衡电桥模式。S260: The current after the fault minus the current before the fault, and then calculate the grounding resistance, and judge whether the branch fault criterion is met. If the branch fault criterion is met, it is judged that the branch is a faulty branch; otherwise, start the unbalanced bridge mode . 2.根据权利要求1所述的变电站直流接地巡检的选线校核方法,其特征在于还包括以下采用归谬法进行校核的步骤:2. The line selection checking method of substation DC grounding inspection according to claim 1, is characterized in that also comprising the following steps of checking by reductio absurdum: S270:根据直流接地巡检选线过程中求得的母线接地电阻,反向推算正、负母线电压的推算值;S270: According to the grounding resistance of the bus bar obtained during the line selection process of the DC grounding inspection, reversely calculate the estimated values of the positive and negative bus bar voltages; S272:将推算所得正、负母线电压推算值,与对应的正、负母线电压实测值进行比较,若正、负母线电压推算值之中的任一项不同于其实测值,则判定选线过程中存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。S272: Compare the estimated positive and negative bus voltages with the corresponding measured positive and negative bus voltages, and if any of the estimated positive and negative bus voltages is different from the measured value, determine the line selection In the process, there is a special situation that the bridge method cannot be accurately calculated, and the online monitoring device sends out a warning message that the line selection result is wrong. 3.根据权利要求2所述的变电站直流接地巡检的选线校核方法,其特征在于在所述的步骤S272之后还包括以下步骤:3. The line selection checking method of substation DC ground inspection according to claim 2, characterized in that after said step S272, the method also includes the following steps: S274:根据选线过程中求得的各支路的正、负母线对地电阻,计算负母线和正母线对地总电阻;S274: Calculate the total resistance of the negative bus and the positive bus to ground according to the positive and negative bus-to-ground resistances of each branch obtained in the line selection process; S276:根据负母线和正母线对地总电阻,反向推算正、负母线电压的推算值:S276: According to the total resistance of the negative busbar and positive busbar to ground, reversely calculate the estimated value of the positive and negative busbar voltage: S278:将推算所得正、负母线电压推算值,与对应的正、负母线电压实测值进行比较,若正、负母线电压推算值之中的任一项不同于其实测值,则判定选线过程中求得的支路中,至少有一路存在电桥法无法准确计算的特殊情况,所述的在线监测装置发出选线结果有误的警示信息。S278: Compare the estimated values of the positive and negative bus voltages with the corresponding measured values of the positive and negative bus voltages. If any of the estimated values of the positive and negative bus voltages is different from its measured value, determine the line selection Among the branches obtained in the process, at least one of the branches has a special situation that the bridge method cannot be accurately calculated, and the online monitoring device sends out a warning message that the result of the line selection is wrong.
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