CN116953422A - Fault sensing method, device, equipment and medium for neutral point ungrounded system - Google Patents

Fault sensing method, device, equipment and medium for neutral point ungrounded system Download PDF

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CN116953422A
CN116953422A CN202310576539.0A CN202310576539A CN116953422A CN 116953422 A CN116953422 A CN 116953422A CN 202310576539 A CN202310576539 A CN 202310576539A CN 116953422 A CN116953422 A CN 116953422A
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distribution network
ground
frequency
impedance
secondary side
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刘红文
唐立军
柴晨超
张春丽
杨金东
杨莉
邓正东
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Electric Power Research Institute of Yunnan Power Grid Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/08—Locating faults in cables, transmission lines, or networks
    • G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
    • G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
    • G01R27/2688—Measuring quality factor or dielectric loss, e.g. loss angle, or power factor
    • G01R27/2694—Measuring dielectric loss, e.g. loss angle, loss factor or power factor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • Y—GENERAL 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
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS 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
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
    • Y04S10/52—Outage or fault management, e.g. fault detection or location

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

本发明实施例公开了一种中性点不接地系统的故障感知方法、装置、设备及介质，注入异频检测电流，确定配电网对地分布电容折算至PT二次侧的电容值和配电网对地分布电容值；注入的参考频率的电流信号，分别确定配电网正常运行时和系统发生单相接地时的配电网阻抗；进而确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；结合配电网对地分布电容值，确定注入参考频率的电流信号下的对地介质损耗正切值；根据对地介质损耗正切值确定中性点不接地系统的故障状态。通过注入电流，实时检测参考频率下的介质损耗因数，以反映配电网对地绝缘电阻的大小，能快速检测出接地故障，并可通过降低注入电流信号的频率提高感知可靠性和灵敏度。

The embodiment of the present invention discloses a fault sensing method, device, equipment and medium for a neutral point ungrounded system, which injects inter-frequency detection current to determine the capacitance value of the distribution network to the ground distribution capacitance converted to the PT secondary side and the distribution The distributed capacitance value of the power grid to the ground; the injected reference frequency current signal determines the impedance of the distribution network during normal operation and when a single-phase grounding occurs in the system; and then determines the distributed capacitance of the distribution network to the ground converted to PT2 The parallel impedance of the secondary side capacitance and the ground transition resistor; combined with the distributed capacitance value of the distribution network to the ground, determine the tangent value of the ground dielectric loss under the current signal injected at the reference frequency; determine the neutral point based on the tangent value of the ground dielectric loss Fault condition of the grounding system. By injecting current, the dielectric loss factor at the reference frequency is detected in real time to reflect the insulation resistance of the distribution network to the ground. Ground faults can be quickly detected, and the sensing reliability and sensitivity can be improved by reducing the frequency of the injected current signal.

Description

中性点不接地系统的故障感知方法、装置、设备及介质Fault sensing methods, devices, equipment and media for ungrounded neutral point systems

技术领域Technical field

本发明涉及配电网接地故障检测技术领域，具体涉及一种中性点不接地系统的故障感知方法、装置、设备及介质。The invention relates to the technical field of ground fault detection in distribution networks, and in particular to a fault sensing method, device, equipment and medium for a neutral point ungrounded system.

背景技术Background technique

配电网高阻接地故障通常伴随电弧的产生，配电线路掉在地面、架空绝缘线故障通常表现为高阻，主动消弧和保护设备不能感知到线路故障，电弧长时间不能抑制，故障点的过电压和漏电流可引发人身触电、森林火灾及相间故障；因此主动抑制和隔离接地故障的前提需要快速检测到高阻故障的发生。因配电线路接地故障电弧随机性较大，故障特征有别于理想的媒介里的空气放电，其物理特性较复杂，阴极压降和阳极压降不对称，电弧电流过零熄灭，过零后发生复燃，电弧阳极和阴极交替发生变化，弧阻呈现非线性变化。为准确检测出高阻接地故障，需要分析接地故障电弧产生和熄灭特性，提出适用于高阻弧光接地故障的感知方法。High-resistance ground faults in distribution networks are usually accompanied by arcs. Distribution lines dropped to the ground or overhead insulated wire faults usually show high resistance. Active arc suppression and protection equipment cannot sense line faults. The arc cannot be suppressed for a long time, and the fault point Overvoltage and leakage current can cause personal electric shock, forest fires and phase-to-phase faults; therefore, the prerequisite for actively suppressing and isolating ground faults requires rapid detection of the occurrence of high-resistance faults. Because the distribution line ground fault arc is highly random, the fault characteristics are different from the air discharge in the ideal medium, and its physical characteristics are complex. The cathode voltage drop and the anode voltage drop are asymmetric, and the arc current crosses zero and is extinguished. When re-ignition occurs, the arc anode and cathode change alternately, and the arc resistance changes nonlinearly. In order to accurately detect high-resistance ground faults, it is necessary to analyze the generation and extinction characteristics of ground fault arcs and propose a sensing method suitable for high-resistance arc ground faults.

现有技术中，高阻故障的感知主要采用被动和主动感知两种方法，被动感知通过检测接地故障发生前后产生的暂态和稳态的电压、电流特征量判断；主动感知通过主动注入工频或高频信号，提取分析反馈的电压和电流特征感知接地故障。但上述高阻故障感知方法工程应用中计算量大，感知可靠性、实时性和灵敏性还存在不足，且目前工程应用中通常仅能感知2kΩ以下的高阻故障。In the existing technology, high-resistance fault sensing mainly adopts two methods: passive and active sensing. Passive sensing judges by detecting the transient and steady-state voltage and current characteristics generated before and after the ground fault occurs; active sensing judges by actively injecting power frequency. Or high-frequency signals, extract and analyze the feedback voltage and current characteristics to sense ground faults. However, the above-mentioned high-resistance fault sensing method requires a large amount of calculation in engineering applications, and there are still deficiencies in sensing reliability, real-time performance, and sensitivity. In current engineering applications, only high-resistance faults below 2 kΩ can usually be sensed.

发明内容Contents of the invention

基于此，有必要针对上述问题，提出一种中性点不接地系统的故障感知方法、装置、设备及介质。Based on this, it is necessary to propose a fault sensing method, device, equipment and medium for the neutral point ungrounded system in response to the above problems.

为实现上述目的，本申请第一方面提供一种中性点不接的地系统的故障感知方法，所述方法包括：In order to achieve the above object, the first aspect of this application provides a fault sensing method for a ground system with an unconnected neutral point. The method includes:

通过注入的第一频率的检测电流和第二频率的检测电流，确定配电网对地分布电容折算至电磁式电压互感器PT二次侧的电容值和配电网对地分布电容值；Through the injected detection current of the first frequency and the detection current of the second frequency, determine the distributed capacitance of the distribution network to the ground converted to the capacitance value of the secondary side of the electromagnetic voltage transformer PT and the distributed capacitance value of the distribution network to the ground;

通过注入的参考频率的电流信号，确定配电网正常运行时在参考频率的电流信号下的参考配电网阻抗和系统发生单相接地时在参考频率的电流信号下的接地配电网阻抗；Through the injected current signal of the reference frequency, the impedance of the reference distribution network under the current signal of the reference frequency when the distribution network is operating normally and the impedance of the grounded distribution network under the current signal of the reference frequency when a single-phase grounding occurs in the system are determined;

根据所述对地分布电容折算至PT二次侧的电容值、参考配电网阻抗、接地配电网阻抗确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；According to the capacitance value of the ground distributed capacitance converted to the PT secondary side, the reference distribution network impedance, and the grounded distribution network impedance, determine the parallel connection of the distribution network ground distributed capacitance converted to the capacitance of the PT secondary side and the ground transition resistance. impedance;

根据所述配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗和所述配电网对地分布电容值，确定注入参考频率的电流信号下的对地介质损耗正切值；According to the distributed capacitance of the distribution network to the ground converted to the parallel impedance of the capacitance of the secondary side of the PT and the ground transition resistance and the distributed capacitance value of the distribution network to the ground, the dielectric loss to the ground is determined under the current signal injected with the reference frequency. tangent value;

根据所述对地介质损耗正切值与阈值之间的比较关系，确定中性点不接地系统的故障状态。According to the comparison relationship between the ground dielectric loss tangent value and the threshold value, the fault state of the neutral point ungrounded system is determined.

进一步的，所述通过注入的第一频率的检测电流和第二频率的检测电流，确定配电网对地分布电容折算至PT二次侧的电容值和配电网对地分布电容值，包括：Further, by injecting the detection current of the first frequency and the detection current of the second frequency, the distributed capacitance of the distribution network to the ground is converted to the capacitance value of the PT secondary side and the distributed capacitance value of the distribution network to the ground, including :

根据所述第一频率的检测电流和第二频率的检测电流，分别确定配电网在第一频率的检测电流下的第一配电网阻抗，以及配电网在第二频率的检测电流下的第二配电网阻抗；According to the detection current of the first frequency and the detection current of the second frequency, the first distribution network impedance of the distribution network under the detection current of the first frequency and the distribution network impedance of the distribution network under the detection current of the second frequency are respectively determined. The impedance of the second distribution network;

根据所述第一配电网阻抗和第二配电网阻抗，确定配电网对地分布电容折算至PT二次侧的电容值；According to the impedance of the first distribution network and the impedance of the second distribution network, determine the capacitance value of the distributed capacitance of the distribution network to the ground converted to the secondary side of the PT;

获取PT变比；Get the PT transformation ratio;

根据所述PT变比和配电网对地分布电容折算至PT二次侧的电容值确定配电网对地分布电容值。The distributed capacitance value of the distribution network to the ground is determined based on the PT transformation ratio and the distributed capacitance of the distribution network to the ground converted to the capacitance value of the PT secondary side.

进一步的，所述根据第一频率的检测电流和第二频率的检测电流，分别确定配电网在第一频率的检测电流下的第一配电网阻抗，以及配电网在第二频率的检测电流下的第二配电网阻抗，具体包括：Further, according to the detection current of the first frequency and the detection current of the second frequency, the first distribution network impedance of the distribution network under the detection current of the first frequency and the impedance of the distribution network at the second frequency are respectively determined. Detect the impedance of the second distribution network under current, including:

第一频率的检测电流下，根据公式确定第一配电网阻抗；Under the detection current of the first frequency, according to the formula Determine the impedance of the first distribution network;

第二频率的检测电流下，根据公式确定第二配电网阻抗；Under the detection current of the second frequency, according to the formula Determine the impedance of the second distribution network;

其中，f1为第一频率的检测电流下检测电流源输出的频率，Z21为第一配电网阻抗，为检测电流源在第一频率的检测电流下的两端电压，/>为检测电源在第一频率的检测电流下的输出电流；f2为第二频率的检测电流下检测电流源输出的频率，Z22为第二配电网阻抗，/>为检测电流源在第二频率的检测电流下的两端电压，/>为检测电源在第二频率的检测电流下的输出电流，j为虚数单位，R2为PT直流电阻和线路电阻RL折算至PT二次侧的电阻值，L2为PT漏电感和线路电感折算至PT二次侧的电感值，CS2为配电网对地分布电容折算至PT二次侧的电容值。Among them, f 1 is the frequency of the detection current source output under the detection current of the first frequency, Z 21 is the impedance of the first distribution network, To detect the voltage across both ends of the current source under the detection current of the first frequency,/> is the output current of the detection power supply under the detection current of the first frequency; f 2 is the frequency of the detection current source output under the detection current of the second frequency, Z 22 is the impedance of the second distribution network,/> To detect the voltage across both ends of the current source under the detection current of the second frequency,/> To detect the output current of the power supply under the detection current of the second frequency, j is an imaginary unit, R 2 is the PT DC resistance and line resistance R L converted to the resistance value of the PT secondary side, L 2 is the PT leakage inductance and line inductance The inductance value converted to the PT secondary side, CS2 is the capacitance value of the distributed capacitance of the distribution network to the ground converted to the PT secondary side.

进一步的，所述根据第一配电网阻抗和第二配电网阻抗，确定配电网对地分布电容折算至PT二次侧的电容值，具体包括：Further, based on the impedance of the first distribution network and the impedance of the second distribution network, determining the distributed capacitance of the distribution network to the ground converted to the capacitance value of the PT secondary side specifically includes:

根据公式确定第一配电网阻抗的虚部；According to the formula Determine the imaginary part of the impedance of the first distribution network;

根据公式确定第二配电网阻抗的虚部；According to the formula Determine the imaginary part of the impedance of the second distribution network;

根据公式确定配电网对地分布电容折算至PT二次侧的电容值；According to the formula Determine the capacitance value of the distributed capacitance of the distribution network to the ground converted to the secondary side of the PT;

ImZ21为第一配电网阻抗的虚部，ImZ22为第二配电网阻抗的虚部。Im Z21 is the imaginary part of the impedance of the first distribution network, and Im Z22 is the imaginary part of the impedance of the second distribution network.

进一步的，根据所述PT变比和所述配电网对地分布电容折算至PT二次侧的电容值确定配电网对地分布电容值，具体包括：Further, the distributed capacitance value of the distribution network to ground is determined based on the PT transformation ratio and the distributed capacitance of the distribution network to ground converted to the capacitance value of the PT secondary side, which specifically includes:

根据公式确定配电网对地分布电容值；其中，CS为配电网对地分布电容值，n为PT变比。According to the formula Determine the distributed capacitance value of the distribution network to the ground; where CS is the distributed capacitance value of the distribution network to the ground, and n is the PT transformation ratio.

进一步的，所述通过注入的参考频率的电流信号，确定配电网正常运行时在参考频率的电流信号下的参考配电网阻抗和系统发生单相接地时在参考频率的电流信号下的接地配电网阻抗,具体包括；Further, by injecting a current signal of a reference frequency, the impedance of the reference distribution network under the current signal of the reference frequency is determined when the distribution network is operating normally and the grounding under the current signal of the reference frequency when a single-phase grounding occurs in the system. Distribution network impedance, specifically including;

根据公式确定参考配电网阻抗；According to the formula Determine the reference distribution network impedance;

根据公式确定接地配电网阻抗；According to the formula Determine grounded distribution network impedance;

其中，为参考频率，/>为电流源注入电流，/>为正常运行时电流源两端的电压；//表示阻抗并联，/>为接地故障时电流源两端的电压，Rd2为接地过渡电阻折算至PT二次侧的电阻。in, is the reference frequency,/> Inject current into the current source,/> It is the voltage across the current source during normal operation; //indicates impedance in parallel, /> is the voltage across the current source during a ground fault, and R d2 is the resistance converted from the ground transition resistance to the secondary side of the PT.

进一步的，所述根据对地分布电容折算至PT二次侧的电容值、参考配电网阻抗、接地配电网阻抗确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗，具体包括；Further, the capacitance and grounding transition of the distribution network's ground distributed capacitance converted to the PT secondary side are determined based on the capacitance value of the ground distributed capacitance converted to the PT secondary side, the reference distribution network impedance, and the grounded distribution network impedance. The parallel impedance of the resistor, specifically including;

根据公式确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；According to the formula Determine the parallel impedance of the distributed capacitance of the distribution network to the ground converted to the capacitance of the secondary side of the PT and the ground transition resistance;

其中Zf02为消除R2、L2影响的配电网对地分布电容折算至PT二次侧的电容CS2与接地过渡电阻Rd2的并联阻抗。Among them, Z f02 is the distributed capacitance of the distribution network to the ground that eliminates the influence of R 2 and L 2 and is converted to the parallel impedance of the capacitance C S2 on the secondary side of the PT and the ground transition resistance R d2 .

进一步的，所述根据配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗和所述配电网对地分布电容值，确定注入参考频率的电流信号下的对地介质损耗正切值，具体包括：根据公式确定注入参考频率的电流信号下的对地介质损耗正切值；其中，ω0是注入电流源频率为f0对应的角频率，δf0为Zf02阻抗角的余角，In为单相接地过渡电阻。Further, based on the distributed capacitance of the distribution network to the ground converted to the parallel impedance of the capacitance of the secondary side of the PT and the ground transition resistance and the distributed capacitance value of the distribution network to the ground, the relative resistance under the current signal injected at the reference frequency is determined. Ground dielectric loss tangent, including: According to the formula Determine the tangent value of the ground dielectric loss under the current signal injected at the reference frequency; where ω 0 is the angular frequency corresponding to the injected current source frequency f 0 , δ f0 is the supplementary angle of the Z f02 impedance angle, and I n is the single-phase ground Transition resistance.

进一步的，根据所述对地介质损耗正切值与阈值之间的比较关系，确定中性点不接地系统的故障状态，包括：Further, based on the comparison relationship between the ground dielectric loss tangent value and the threshold value, the fault state of the neutral point ungrounded system is determined, including:

确定参考频率的电流信号下的对地介质损耗正切值；Determine the tangent value of the ground dielectric loss under the current signal at the reference frequency;

若所述对地介质损耗正切值大于所述阈值，则所述中性点不接地系统发生接地故障；If the tangent value of the ground dielectric loss is greater than the threshold value, a ground fault occurs in the ungrounded neutral point system;

若所述对地介质损耗正切值小于等于所述阈值，则所述中性点不接地系统正常运行。If the tangent value of the ground dielectric loss is less than or equal to the threshold value, the neutral point ungrounded system operates normally.

为实现上述目的，本申请第二方面提供一种中性点不接地系统的故障感知装置，其特征在于，所述装置包括：In order to achieve the above object, the second aspect of this application provides a fault sensing device for a neutral point ungrounded system, which is characterized in that the device includes:

控制单元，用于通过注入的第一频率的检测电流和第二频率的检测电流，确定配电网对地分布电容折算至电磁式电压互感器PT二次侧的电容值和配电网对地分布电容值；A control unit configured to determine the capacitance value of the distribution network to the ground by converting the distributed capacitance of the distribution network to the ground into the secondary side of the electromagnetic voltage transformer PT and the value of the distribution network to the ground through the injected detection current of the first frequency and the detection current of the second frequency. Distributed capacitance value;

所述控制单元，还用于通过注入的参考频率的电流信号，确定配电网正常运行时在参考频率的电流信号下的参考配电网阻抗和系统发生单相接地时在参考频率的电流信号下的接地配电网阻抗；The control unit is also used to determine the reference distribution network impedance under the current signal at the reference frequency when the distribution network is operating normally and the current signal at the reference frequency when a single-phase grounding occurs in the system through the injected current signal at the reference frequency. The impedance of the grounded distribution network under

所述控制单元，还用于根据所述对地分布电容折算至PT二次侧的电容值、参考配电网阻抗、接地配电网阻抗确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；The control unit is also used to determine the distribution network's ground distributed capacitance to be converted to the PT secondary side based on the capacitance value of the ground distributed capacitance converted to the PT secondary side, the reference distribution network impedance, and the grounded distribution network impedance. The parallel impedance of the capacitance and the ground transition resistance;

所述控制单元，还用于根据所述配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗和所述配电网对地分布电容值，确定注入参考频率的电流信号下的对地介质损耗正切值；The control unit is also configured to determine the injection reference frequency based on the distributed capacitance of the distribution network to ground converted to the parallel impedance of the capacitance of the secondary side of the PT and the ground transition resistance and the distributed capacitance value of the distribution network to ground. Tangent value of dielectric loss to ground under current signal;

故障判断单元，用于根据所述对地介质损耗正切值与阈值之间的比较关系，确定中性点不接地系统的故障状态。A fault judgment unit is used to determine the fault state of the neutral point ungrounded system based on the comparison relationship between the ground dielectric loss tangent value and the threshold value.

为实现上述目的，本申请第三方面提供一种计算机设备，包括存储器和处理器，所述存储器存储有计算机程序，所述计算机程序被所述处理器执行时，使得所述处理器执行如第一方面所述方法的步骤。In order to achieve the above object, a third aspect of the present application provides a computer device, including a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, the processor executes the following steps: The steps of the method in one aspect.

为实现上述目的，本申请第四方面提供一种计算机可读存储介质，存储有计算机程序，所述计算机程序被处理器执行时，使得所述处理器执行如第一方面所述方法的步骤。To achieve the above object, a fourth aspect of the present application provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the computer program causes the processor to execute the steps of the method described in the first aspect.

采用本发明实施例，具有如下有益效果：Adopting the embodiments of the present invention has the following beneficial effects:

本发明通过在配电网中性点和地之间，通过电磁式电压互感器向配电网注入异频检测电流，确定配电网对地分布电容折算至电磁式电压互感器PT二次侧的电容值和配电网对地分布电容值；通过注入的参考频率的电流信号，实时检测配电网在参考频率的电流信号下的介质损耗正切值tgδf0，tgδf0反映了配电网对地绝缘电阻的大小，当tgδf0超过设定阈值时，可判断配电网发生接地故障。本发明提出的感知方法，通过介质损耗正切值判断接地故障，这种感知方法的计算量更小，灵敏度更高，更符合工程应用要求。This invention injects a different frequency detection current into the distribution network through an electromagnetic voltage transformer between the neutral point of the distribution network and the ground, and determines that the distributed capacitance of the distribution network to the ground is converted to the secondary side of the electromagnetic voltage transformer PT. capacitance value and the distributed capacitance value of the distribution network to the ground; through the injected current signal of the reference frequency, the dielectric loss tangent value tgδ f0 of the distribution network under the current signal of the reference frequency is detected in real time. tgδ f0 reflects the relationship between the distribution network and the ground. The size of the ground insulation resistance. When tgδ f0 exceeds the set threshold, it can be determined that a ground fault has occurred in the distribution network. The sensing method proposed by the present invention determines ground faults through the tangent value of dielectric loss. This sensing method requires less calculation, has higher sensitivity, and is more in line with engineering application requirements.

附图说明Description of the drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting creative efforts.

其中：in:

图1为一个实施例中中性点不接地系统的故障感知方法的流程示意图；Figure 1 is a schematic flowchart of a fault sensing method for an ungrounded neutral point system in one embodiment;

图2为一个实施例中中性点不接地系统的故障感知装置的等效零序回路图；Figure 2 is an equivalent zero sequence loop diagram of a fault sensing device of an ungrounded neutral point system in one embodiment;

图3为一个实施例中中性点不接地系统的故障感知装置的等效简化零序回路图；Figure 3 is an equivalent simplified zero sequence loop diagram of a fault sensing device of an ungrounded neutral point system in one embodiment;

图4为一个实施例中中性点不接地系统的故障感知装置在接地故障时介质损耗正切值变化图。Figure 4 is a diagram showing the change of the dielectric loss tangent value of the fault sensing device of the neutral point ungrounded system when a ground fault occurs in one embodiment.

图5为一个实施例中中性点不接地系统的接地故障感知装置的结构示意图。Figure 5 is a schematic structural diagram of a ground fault sensing device of an ungrounded neutral point system in one embodiment.

具体实施方式Detailed ways

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

在本申请实施例中，提供中性点不接地系统的故障感知方法，请参阅图1，图1为一个实施例中中性点不接地系统的故障感知方法的流程示意图，中性点不接地系统的故障感知方法包括步骤S110至步骤S150。In the embodiment of this application, a fault sensing method for an ungrounded neutral point system is provided. Please refer to Figure 1. Figure 1 is a schematic flow chart of a fault sensing method for an ungrounded neutral point system in one embodiment. The neutral point is not grounded. The system fault sensing method includes steps S110 to S150.

在本申请的实施例中，图2示出了中性点不接地系统的故障感知装置的等效零序回路图，其中，为检测电流源；IH为配电网对地分布电容；In为单相接地过渡电阻；N点为配电系统中性点，设该点电压为/>PT为电磁式电压互感器，PT与配电网中性点连接的一侧为一次侧，变比为n；RL为系统线路直流电阻；L为系统线路电感。In the embodiment of the present application, Figure 2 shows the equivalent zero sequence loop diagram of the fault sensing device of the neutral point ungrounded system, where, is the detection current source; I H is the distributed capacitance of the distribution network to the ground; I n is the single-phase ground transition resistance; N point is the neutral point of the distribution system, and the voltage at this point is /> PT is an electromagnetic voltage transformer. The side connected to the neutral point of the distribution network is the primary side, and the transformation ratio is n; R L is the DC resistance of the system line; L is the inductance of the system line.

忽略PT的励磁阻抗，从PT二次侧看进去，得到如图3所示中性点不接地系统的故障感知装置的等效简化零序回路图。Ignoring the excitation impedance of the PT and looking from the secondary side of the PT, the equivalent simplified zero sequence loop diagram of the fault sensing device of the neutral point ungrounded system is obtained as shown in Figure 3.

参见图3，图中，为检测电流源；R2为PT直流电阻和线路电阻RL折算至PT二次侧的电阻；L2为PT漏电感和线路电感折算至PT二次侧的电感；CS2为配电网对地分布电容折算至PT二次侧的电容；Rd2为接地过渡电阻折算至PT二次侧的电阻。CS2和IH之间的计算关系式为：CS2＝n2CS，In和Rd2之间的计算关系式为：Rd2＝Rd/n2。See Figure 3. In the figure, is the detection current source; R 2 is the resistance of PT DC resistance and line resistance R L converted to the secondary side of PT; L 2 is the inductance of PT leakage inductance and line inductance converted to the secondary side of PT; C S2 is the distribution network pair The ground distributed capacitance is converted to the capacitance of the PT secondary side; R d2 is the ground transition resistance converted to the resistance of the PT secondary side. The calculation relationship between CS2 and I H is: C S2 =n 2 CS , and the calculation relationship between In and R d2 is: R d2 =R d /n 2 .

步骤S110，通过注入的第一频率的检测电流和第二频率的检测电流，确定配电网对地分布电容折算至电磁式电压互感器PT二次侧的电容值和配电网对地分布电容值；Step S110, through the injected detection current of the first frequency and the detection current of the second frequency, determine the distributed capacitance of the distribution network to the ground converted to the capacitance value of the secondary side of the electromagnetic voltage transformer PT and the distributed capacitance of the distribution network to the ground. value;

进一步的，步骤S110具体包括步骤S210至步骤S240。Further, step S110 specifically includes steps S210 to S240.

步骤S210，根据所述第一频率的检测电流和第二频率的检测电流，分别确定配电网在第一频率的检测电流下的第一配电网阻抗，以及配电网在第二频率的检测电流下的第二配电网阻抗；Step S210: According to the detected current of the first frequency and the detected current of the second frequency, respectively determine the impedance of the first distribution network under the detected current of the first frequency and the impedance of the distribution network under the second frequency. Detect the impedance of the second distribution network under current;

步骤S220，根据所述第一配电网阻抗和第二配电网阻抗，确定配电网对地分布电容折算至PT二次侧的电容值。Step S220: Based on the impedance of the first distribution network and the impedance of the second distribution network, determine the capacitance value of the distributed capacitance of the distribution network to the ground converted to the secondary side of the PT.

进一步的，在具体地实施方式中，配电网正常运行时，即接地过渡电阻Rd2无穷大，此时检测电流源输出第一频率的检测电流f1和第二频率的检测电流f2，测得第一频率的检测电流f1下的电压第二频率的检测电流f2下的电压/>则有：Further, in a specific embodiment, when the distribution network is operating normally, that is, the ground transition resistance R d2 is infinite, at this time the detection current source outputs the detection current f 1 of the first frequency and the detection current f 2 of the second frequency, and the detection current f 1 and the detection current f 2 of the second frequency are measured. Obtain the voltage under the detection current f 1 of the first frequency Voltage under detection current f 2 of the second frequency/> Then there are:

第一频率的检测电流下，根据公式确定第一配电网阻抗；Under the detection current of the first frequency, according to the formula Determine the impedance of the first distribution network;

第二频率的检测电流下，根据公式确定第二配电网阻抗；Under the detection current of the second frequency, according to the formula Determine the impedance of the second distribution network;

其中，f1为第一频率的检测电流下检测电流源输出的频率，Z21为第一配电网阻抗，为检测电流源在第一频率的检测电流下的两端电压，/>为检测电源在第一频率的检测电流下的输出电流；f2为第二频率的检测电流下检测电流源输出的频率，Z22为第二配电网阻抗，/>为检测电流源在第二频率的检测电流下的两端电压，/>为检测电源在第二频率的检测电流下的输出电流，j为虚数单位，R2为PT直流电阻和线路电阻RL折算至PT二次侧的电阻值，L2为PT漏电感和线路电感折算至PT二次侧的电感值，CS2为配电网对地分布电容折算至PT二次侧的电容值。Among them, f 1 is the frequency of the detection current source output under the detection current of the first frequency, Z 21 is the impedance of the first distribution network, To detect the voltage across both ends of the current source under the detection current of the first frequency,/> is the output current of the detection power supply under the detection current of the first frequency; f 2 is the frequency of the detection current source output under the detection current of the second frequency, Z 22 is the impedance of the second distribution network,/> To detect the voltage across both ends of the current source under the detection current of the second frequency,/> To detect the output current of the power supply under the detection current of the second frequency, j is an imaginary unit, R 2 is the PT DC resistance and line resistance R L converted to the resistance value of the PT secondary side, L 2 is the PT leakage inductance and line inductance The inductance value converted to the PT secondary side, CS2 is the capacitance value of the distributed capacitance of the distribution network to the ground converted to the PT secondary side.

由上式Z21、Z22的实部相等，其值都为R2值。上式虚部分别设为ImZ21和ImZ22，则在具体地实施方式中，根据公式确定第一配电网阻抗的虚部；From the above formulas, the real parts of Z 21 and Z 22 are equal, and their values are both R 2 values. The imaginary parts of the above formula are respectively set to Im Z21 and Im Z22 , then in the specific implementation, according to the formula Determine the imaginary part of the impedance of the first distribution network;

根据公式确定第二配电网阻抗的虚部；According to the formula Determine the imaginary part of the impedance of the second distribution network;

将两个公式合并为方程组，解得：以此确定配电网对地分布电容折算至PT二次侧的电容值。Combine the two formulas into a system of equations and solve: In this way, the distributed capacitance of the distribution network to the ground is converted to the capacitance value of the PT secondary side.

步骤S230，获取PT变比，具体地，变比可通过铭牌获得，或检测得到。Step S230: Obtain the PT transformation ratio. Specifically, the transformation ratio can be obtained from the nameplate or detected.

步骤S240，根据所述PT变比和配电网对地分布电容折算至PT二次侧的电容值确定配电网对地分布电容值；Step S240, determine the distribution network-to-ground distributed capacitance value based on the PT transformation ratio and the distribution network-to-ground distributed capacitance converted to the capacitance value of the PT secondary side;

在具体地实施方式中，通过CS2和CS之间的计算关系式：CS2＝n2Cs，可计算得到配电网对地分布电容值CS。In a specific implementation, the distributed capacitance value C S of the distribution network to the ground can be calculated through the calculation relationship between CS2 and CS : CS2 =n 2 C s .

步骤S120，通过注入的参考频率的电流信号，确定配电网正常运行时在参考频率的电流信号下的参考配电网阻抗和系统发生单相接地时在参考频率的电流信号下的接地配电网阻抗；Step S120, through the injected current signal of the reference frequency, determine the reference distribution network impedance under the current signal of the reference frequency when the distribution network is operating normally and the grounded power distribution under the current signal of the reference frequency when a single-phase grounding occurs in the system. Network impedance;

进一步的，步骤S120具体包括：Further, step S120 specifically includes:

根据公式确定配电网正常运行时，注入参考频率的电流信号下的参考配电网阻抗；According to the formula Determine the impedance of the reference distribution network under the injection of a current signal with a reference frequency when the distribution network is operating normally;

根据公式确定当系统发生单相接地时，注入参考频率的电流信号下的接地配电网阻抗；According to the formula Determine the impedance of the grounded distribution network under the injection of a current signal with a reference frequency when a single-phase grounding occurs in the system;

其中，f0为参考频率，为电流源注入电流，/>为正常运行时电流源两端的电压；//表示阻抗并联，/>为接地故障时电流源两端的电压，Rd2为接地过渡电阻折算至PT二次侧的电阻。Among them, f 0 is the reference frequency, Inject current into the current source,/> It is the voltage across the current source during normal operation; //indicates impedance in parallel, /> is the voltage across the current source during a ground fault, and R d2 is the resistance converted from the ground transition resistance to the secondary side of the PT.

步骤S130，根据所述对地分布电容折算至PT二次侧的电容值、参考配电网阻抗、接地配电网阻抗确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；Step S130, determine the capacitance and grounding transition of the distribution network's ground distributed capacitance converted to the PT secondary side based on the capacitance value of the ground distributed capacitance converted to the PT secondary side, the reference distribution network impedance, and the grounded distribution network impedance. The parallel impedance of the resistor;

进一步的，步骤S130具体包括：Further, step S130 specifically includes:

根据公式确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；According to the formula Determine the parallel impedance of the distributed capacitance of the distribution network to the ground converted to the capacitance of the secondary side of the PT and the ground transition resistance;

其中Zf02为消除R2、L2影响的配电网对地分布电容折算至PT二次侧的电容CS2与接地过渡电阻Rd2的并联阻抗。Among them, Z f02 is the distributed capacitance of the distribution network to the ground that eliminates the influence of R 2 and L 2 and is converted to the parallel impedance of the capacitance C S2 on the secondary side of the PT and the ground transition resistance R d2 .

步骤S140，根据所述配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗，确定注入参考频率的电流信号下的对地介质损耗正切值；Step S140, determine the tangent value of the ground dielectric loss under the current signal injected at the reference frequency based on the distributed capacitance of the distribution network to the ground converted to the parallel impedance of the capacitance of the secondary side of the PT and the ground transition resistance;

进一步的，步骤S140具体包括：引入“介质损耗正切值”的概念，配电线路接地故障破坏了系统绝缘，接地过渡电阻增加了损耗，配电网在参考频率f0下的介质损耗正切值为：Further, step S140 specifically includes: introducing the concept of "dielectric loss tangent value". The ground fault of the distribution line destroys the system insulation, and the ground transition resistance increases the loss. The dielectric loss tangent value of the distribution network at the reference frequency f 0 is :

其中，ω0是注入电流源频率为f0对应的角频率，δf0为Zf02阻抗角的余角，Rd为单相接地过渡电阻。根据此公式可知，tgδf0与电流源注入的参考频率f0和配电网对地分布电容值CS成反比。tgδf0反映了配电网对地泄露电阻的大小，当tgδf0增大到一定数值时，可判断配电网发生接地故障。 Among them, ω 0 is the angular frequency corresponding to the injection current source frequency f 0 , δ f0 is the supplementary angle of the Z f02 impedance angle, and R d is the single-phase grounding transition resistance. According to this formula, it can be seen that tgδ f0 is inversely proportional to the reference frequency f 0 injected by the current source and the distributed capacitance value C S of the distribution network to the ground. tgδ f0 reflects the leakage resistance of the distribution network to the ground. When tgδ f0 increases to a certain value, it can be judged that a ground fault has occurred in the distribution network.

步骤S150，根据所述对地介质损耗正切值与阈值之间的比较关系，确定中性点不接地系统的故障状态；在本申请的实施例中，tgδf0反映了配电网对地绝缘电阻的大小，当tgδf0超过设定阈值时，可判断配电网发生接地故障，该阈值一般为0.01～0.2。本申请中以0.05示例。Step S150: Determine the fault state of the ungrounded neutral point system based on the comparison between the ground dielectric loss tangent and the threshold; in the embodiment of the present application, tgδ f0 reflects the ground insulation resistance of the distribution network When tgδ f0 exceeds the set threshold, it can be judged that a ground fault has occurred in the distribution network. The threshold is generally 0.01 to 0.2. In this application, 0.05 is used as an example.

进一步的，步骤S150具体包括：Further, step S150 specifically includes:

确定参考频率的电流信号下的对地介质损耗正切值；Determine the tangent value of the ground dielectric loss under the current signal at the reference frequency;

若所述对地介质损耗正切值大于所述阈值，则所述中性点不接地系统发生接地故障；If the tangent value of the ground dielectric loss is greater than the threshold value, a ground fault occurs in the ungrounded neutral point system;

若所述对地介质损耗正切值小于等于所述阈值，则所述中性点不接地系统正常运行。If the tangent value of the ground dielectric loss is less than or equal to the threshold value, the neutral point ungrounded system operates normally.

采用本实施例的技术方案，提高了检测接地故障的灵敏度，能够快速判断系统是否发生单相接地故障，且计算更为简单Adopting the technical solution of this embodiment improves the sensitivity of detecting ground faults, can quickly determine whether a single-phase ground fault occurs in the system, and the calculation is simpler

参见图4，图4为中性点不接地系统的故障感知装置在接地故障时介质损耗正切值变化图，假设10kV配电网中性点不接地系统，电容电流为1A～100A，接地过渡电阻为1kΩ～100kΩ，依据获得电流源注入参考频率f0为8Hz时的tgδf0变化情况如图所示。Refer to Figure 4. Figure 4 is a diagram showing the change of the dielectric loss tangent value of the fault sensing device of the ungrounded neutral point system during a ground fault. Assume that the neutral point of the 10kV distribution network is ungrounded, the capacitive current is 1A to 100A, and the ground transition resistance 1kΩ～100kΩ, based on The change of tgδ f0 when the current source injection reference frequency f 0 is 8Hz is obtained, as shown in the figure.

可以看出，接地故障过渡电阻一定的条件下，配电网电容电流越大，tgδf0越小；配电网电容电流一定的条件下，接地过渡电阻越大，tgδf0越小；电容电流和接地故障电阻随tgδf0的增大而减小。电流源注入信号的参考频率f0宜采用低频值，检测电源形成的容抗增大，相同接地过渡电阻在频率f0下的tgδf0增大，提高了故障感知灵敏度。It can be seen that under the condition that the ground fault transition resistance is certain, the larger the distribution network capacitance current is, the smaller tgδ f0 is; under the condition that the distribution network capacitance current is certain, the larger the ground fault transition resistance is, the smaller tgδ f0 is; the capacitance current and The ground fault resistance decreases with the increase of tgδ f0 . The reference frequency f 0 of the current source injection signal should be a low-frequency value. The capacitive reactance formed by the detection power supply increases, and the tgδ f0 of the same ground transition resistance at the frequency f 0 increases, which improves the fault sensing sensitivity.

参考频率越小，选取同样的限值，可以增大感知范围，参考频率一般为1Hz～20Hz，本申请中以8Hz为例。The smaller the reference frequency, the same limit value can be selected to increase the sensing range. The reference frequency is generally 1Hz to 20Hz. In this application, 8Hz is taken as an example.

配电网正常运行时，tgδf0接近零，本文电流源注入参考频率为f0＝8Hz，以介质损耗增量Δtgδf0＝0.05为接地故障判断限值，配电网介质损耗正切值变化量超过该值时为发生单相接地。计算可得电容电流为100A时，可感知7kΩ及以下的高阻接地故障。随着电容电流的降低，可感知的接地过渡电阻范围增大，当电容电流在50A以下时，可感知14kΩ及以下的高阻接地故障，当电容电流在30A以下时，可感知24kΩ及以下的高阻接地故障，当电容电流在10A以下时，可感知72kΩ及以下的高阻接地故障。When the distribution network is operating normally, tgδ f0 is close to zero. The current source injection reference frequency in this article is f 0 =8Hz. The dielectric loss increment Δtgδ f0 =0.05 is used as the ground fault judgment limit. The change in the tangent value of the distribution network dielectric loss exceeds At this value, a single-phase ground fault occurs. It is calculated that when the capacitor current is 100A, high-resistance ground faults of 7kΩ and below can be sensed. As the capacitor current decreases, the perceptible ground transition resistance range increases. When the capacitor current is below 50A, high-resistance ground faults of 14kΩ and below can be perceived. When the capacitor current is below 30A, high-resistance ground faults of 24kΩ and below can be perceived. High-resistance ground fault, when the capacitor current is below 10A, high-resistance ground faults of 72kΩ and below can be sensed.

依据国家标准GB/T 50064交流电气装置的过电压保护和绝缘配合设计规范，配电网电容电流大于10A，应采用消弧线圈接地，因此本申请提出的高阻故障感知方法有较高的灵敏度。显然地，电流源注入频率8Hz，通过实时检测配电网介质损耗正切值增量Δtgδf0＝0.05，可有效检测出配电网中性点不接地系统24kΩ的接地故障，满足工程应用要求。According to the national standard GB/T 50064 Overvoltage Protection and Insulation Coordination Design Specification for AC Electrical Devices, if the capacitance current of the distribution network is greater than 10A, an arc suppression coil should be used for grounding. Therefore, the high-resistance fault sensing method proposed in this application has high sensitivity. . Obviously, the current source injection frequency is 8Hz, and through real-time detection of the distribution network dielectric loss tangent value increment Δtgδ f0 = 0.05, the 24kΩ ground fault of the ungrounded neutral point system of the distribution network can be effectively detected, meeting the engineering application requirements.

在本申请实施例中，提供中性点不接地系统的故障感知装置，请参阅图5，图5为一个实施例中中性点不接地系统的接地故障感知装置的结构示意图，该中性点不接地系统的故障感知装置包括：控制单元102和故障判断单元104。In the embodiment of the present application, a fault sensing device for an ungrounded neutral point system is provided. Please refer to Figure 5. Figure 5 is a schematic structural diagram of a ground fault sensing device for an ungrounded neutral point system in one embodiment. The neutral point The fault sensing device of the ungrounded system includes: a control unit 102 and a fault judgment unit 104.

其中，控制单元102，被配置为通过注入的第一频率的检测电流和第二频率的检测电流，确定配电网对地分布电容折算至电磁式电压互感器PT二次侧的电容值和配电网对地分布电容值；该控制单元102的具体功能及处理还参见步骤S110。Among them, the control unit 102 is configured to determine the capacitance value of the distribution network to the ground distributed capacitance converted to the secondary side of the electromagnetic voltage transformer PT through the injected detection current of the first frequency and the detection current of the second frequency. The distributed capacitance value of the power grid to the ground; for the specific functions and processing of the control unit 102, please also refer to step S110.

控制单元102，还被配置为通过注入的参考频率的电流信号，确定配电网正常运行时在参考频率的电流信号下的参考配电网阻抗和系统发生单相接地时在参考频率的电流信号下的接地配电网阻抗；该控制单元102的具体功能及处理还参见步骤S120。The control unit 102 is also configured to determine the reference distribution network impedance under the current signal at the reference frequency when the distribution network is operating normally and the current signal at the reference frequency when a single-phase grounding occurs in the system through the injected current signal at the reference frequency. The impedance of the ground distribution network is below; for the specific functions and processing of the control unit 102, please also refer to step S120.

控制单元102，还被配置为根据所述对地分布电容折算至PT二次侧的电容值、参考配电网阻抗、接地配电网阻抗确定配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗；该控制单元102的具体功能及处理还参见步骤S130。The control unit 102 is also configured to determine the distribution network's ground distributed capacitance converted to the PT secondary side based on the capacitance value of the ground distributed capacitance converted to the PT secondary side, the reference distribution network impedance, and the grounded distribution network impedance. The parallel impedance of the capacitance and the ground transition resistor; please also refer to step S130 for the specific functions and processing of the control unit 102.

控制单元102，还被配置为根据所述配电网对地分布电容折算至PT二次侧的电容与接地过渡电阻的并联阻抗和所述配电网对地分布电容值，确定注入参考频率的电流信号下的对地介质损耗正切值；该控制单元102的具体功能及处理还参见步骤S140。The control unit 102 is also configured to determine the injection reference frequency based on the distributed capacitance of the distribution network to the ground converted to the parallel impedance of the capacitance of the PT secondary side and the ground transition resistance and the distributed capacitance value of the distribution network to the ground. The tangent value of the ground dielectric loss under the current signal; for the specific functions and processing of the control unit 102, please also refer to step S140.

故障判断单元104，被配置为根据所述对地介质损耗正切值与阈值之间的比较关系，确定中性点不接地系统的故障状态；该故障判断单元104的具体功能及处理还参见步骤S150。The fault judgment unit 104 is configured to determine the fault state of the neutral point ungrounded system based on the comparison relationship between the ground dielectric loss tangent value and the threshold value; for the specific functions and processing of the fault judgment unit 104, please also refer to step S150 .

采用本实施例的技术方案，适用于配电网中性点不接地系统，能够快速判断系统是否发生单相接地故障，灵敏度更高，更加可靠。The technical solution of this embodiment is suitable for systems with ungrounded neutral points in distribution networks, and can quickly determine whether a single-phase ground fault occurs in the system, with higher sensitivity and reliability.

在一个实施例中，提出了一种计算机设备，包括存储器和处理器，所述存储器存储有计算机程序，所述计算机程序被所述处理器执行时，使得所述处理器执行上述方法实施例中的各个步骤。In one embodiment, a computer device is proposed, including a memory and a processor. The memory stores a computer program. When the computer program is executed by the processor, it causes the processor to execute the above method embodiment. various steps.

在一个实施例中，提出了一种计算机可读存储介质，存储有计算机程序，所述计算机程序被处理器执行时，使得所述处理器执行上述方法实施例中的各个步骤。In one embodiment, a computer-readable storage medium is proposed, which stores a computer program. When the computer program is executed by a processor, it causes the processor to execute each step in the above method embodiment.

本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成，所述的程序可存储于一非易失性计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，本申请所提供的各实施例中所使用的对存储器、存储、数据库或其它介质的任何引用，均可包括非易失性和/或易失性存储器。非易失性存储器可包括只读存储器(ROM)、可编程ROM(PROM)、电可编程ROM(EPROM)、电可擦除可编程ROM(EEPROM)或闪存。易失性存储器可包括随机存取存储器(RAM)或者外部高速缓冲存储器。作为说明而非局限，RAM以多种形式可得，诸如静态RAM(SRAM)、动态RAM(DRAM)、同步DRAM(SDRAM)、双数据率SDRAM(DDRSDRAM)、增强型SDRAM(ESDRAM)、同步链路(Synchlink)DRAM(SLDRAM)、存储器总线(Rambus)直接RAM(RDRAM)、直接存储器总线动态RAM(DRDRAM)、以及存储器总线动态RAM(RDRAM)等。Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be implemented by instructing relevant hardware through computer programs. The programs can be stored in a non-volatile computer-readable storage medium. , when the program is executed, it may include the processes of the above-mentioned method embodiments. Any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and/or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous chain Synchlink DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

以上实施例的各技术特征可以进行任意的组合，为使描述简洁，未对上述实施例中的各个技术特征所有可能的组合都进行描述，然而，只要这些技术特征的组合不存在矛盾，都应当认为是本说明书记载的范围。The technical features of the above embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, all possible combinations should be used. It is considered to be within the scope of this manual.

以上所述实施例仅表达了本申请的几种实施方式，其描述较为具体和详细，但并不能因此而理解为对本申请专利范围的限制。应当指出的是，对于本领域的普通技术人员来说，在不脱离本申请构思的前提下，还可以做出若干变形和改进，这些都属于本申请的保护范围。因此，本申请专利的保护范围应以所附权利要求为准。The above-described embodiments only express several implementation modes of the present application, and their descriptions are relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all fall within the protection scope of the present application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims (12)

1. A method of fault perception of a neutral point ungrounded ground system, the method comprising:
determining a capacitance value converted from the distribution network to the secondary side of the electromagnetic voltage transformer PT and a distribution network to the ground distributed capacitance value through the injected detection current of the first frequency and the injected detection current of the second frequency;
determining reference power distribution network impedance under the reference frequency current signal and grounding power distribution network impedance under the reference frequency current signal when the power distribution network normally operates and the system is in single-phase grounding through the injected reference frequency current signal;
determining the parallel impedance of the capacitance converted from the power distribution network to the PT secondary side and the grounding transition resistance according to the capacitance value converted from the grounding distribution capacitance to the PT secondary side, the reference power distribution network impedance and the grounding power distribution network impedance;
determining a dielectric loss tangent value to the ground under a current signal injected with a reference frequency according to the parallel impedance of the capacitance of the power distribution network to the ground distributed capacitance converted to the PT secondary side and the ground transition resistance and the power distribution network to the ground distributed capacitance value;
and determining the fault state of the neutral point ungrounded system according to the comparison relation between the dielectric loss tangent value to the ground and the threshold value.
2. The fault sensing method of a neutral point ungrounded system according to claim 1, wherein determining the capacitance value of the distribution network to ground distributed capacitance converted to the PT secondary side and the distribution network to ground distributed capacitance value by injecting the detection current of the first frequency and the detection current of the second frequency comprises:
according to the detection current of the first frequency and the detection current of the second frequency, respectively determining a first power distribution network impedance of the power distribution network under the detection current of the first frequency and a second power distribution network impedance of the power distribution network under the detection current of the second frequency;
determining a capacitance value converted from the distribution network to the ground distributed capacitance to the PT secondary side according to the first distribution network impedance and the second distribution network impedance;
obtaining PT transformation ratio;
and determining the distribution network ground distributed capacitance value according to the PT transformation ratio and the capacitance value converted from the distribution network ground distributed capacitance to the PT secondary side.
3. The fault sensing method of a neutral point ungrounded system according to claim 2, wherein the determining the first distribution network impedance of the distribution network at the first frequency of the detected current and the second distribution network impedance of the distribution network at the second frequency of the detected current according to the first frequency of the detected current and the second frequency of the detected current respectively specifically includes:
at the detection current of the first frequency, according to the formulaDetermining a first power distribution network impedance;
at the detection current of the second frequency, according to the formulaDetermining a second power distribution network impedance;
wherein f 1 The frequency of the output of the current source is detected under the detection current of the first frequency, Z 21 For the first distribution network impedance,for detecting the voltage across the current source at the detection current of the first frequency, < >>Detecting an output current of the power supply at a detection current of a first frequency; f (f) 2 The frequency Z of the output of the detection current source under the detection current of the second frequency 22 For the second distribution network impedance, < >>For detecting the voltage across the current source at the second frequency of the detection current, ">To detect the output current of the power supply at the second frequency, j is an imaginary unit, R 2 Is PT DC resistance and line resistance R L The resistance value is converted to PT secondary side, L 2 The PT leakage inductance and the line inductance are converted into the inductance value of the PT secondary side, C S2 And converting the distributed capacitance of the power distribution network to the capacitance value of the PT secondary side.
4. A method for sensing a fault in a neutral point ungrounded system according to claim 3, wherein determining a capacitance value of the distribution network to ground distributed capacitance converted to a PT secondary side according to the first distribution network impedance and the second distribution network impedance specifically includes:
according to the formulaDetermining an imaginary part of the first distribution network impedance;
according to the formulaDetermining an imaginary part of the second distribution network impedance;
according to the formulaDetermining a capacitance value of the power distribution network to be converted into a PT secondary side by the distributed capacitance to the ground;
Im Z21 for the imaginary part, im, of the impedance of the first distribution network Z22 Is the imaginary part of the second distribution network impedance.
5. The method for sensing faults in a neutral point ungrounded system according to claim 4, wherein determining a distribution network ground distributed capacitance value from the PT transformation ratio and the capacitance value of the distribution network ground distributed capacitance converted to a PT secondary side specifically comprises:
according to the formulaDetermining a distributed capacitance value of the power distribution network to the ground; wherein C is S And the capacitance value is distributed for the power distribution network to the ground, and n is PT transformation ratio.
6. The fault sensing method of a neutral point ungrounded system according to any of claims 1-5, wherein the determining the reference distribution network impedance under the reference frequency current signal when the distribution network is operating normally and the grounded distribution network impedance under the reference frequency current signal when the system is single-phase grounded by the injected reference frequency current signal specifically comprises;
according to the formulaDetermining a reference power distribution network impedance;
according to the formulaDetermining the impedance of a grounded power distribution network;
wherein f 0 As a reference to the frequency of the reference,injecting current into the current source, ">Is the voltage at two ends of the current source during normal operation; the impedance parallel is denoted by// and, and (2)>To the voltage across the current source at ground fault, R d2 The transition resistance to ground translates to the resistance on the secondary side of PT.
7. The fault sensing method of the neutral point ungrounded system according to claim 6, wherein determining the parallel impedance of the capacitance of the distribution network to ground distributed capacitance to the PT secondary side and the ground transition resistance according to the capacitance value of the distribution network to ground distributed capacitance to the PT secondary side, the reference distribution network impedance, and the ground distribution network impedance specifically comprises;
according to the formulaDetermining the parallel impedance of a capacitor converted from the distribution network to the PT secondary side and the grounding transition resistance;
wherein Z is f02 To eliminate R 2 、L 2 The capacitance C of the affected distribution network to the ground distributed capacitance to the PT secondary side S2 And a ground transition resistance R d2 Is a parallel impedance of (c).
8. The fault sensing method of a neutral point ungrounded system according to claim 7, wherein determining a dielectric loss tangent value to ground under a current signal injected with a reference frequency according to a parallel impedance of a capacitance of a power distribution network to ground distributed capacitance converted to a capacitance of a PT secondary side and a ground transition resistance and a power distribution network to ground distributed capacitance value specifically comprises: according to the formulaDetermining a dielectric loss tangent to ground at a current signal injected at a reference frequency; wherein omega 0 Is to inject a current source with a frequency f 0 Corresponding angular frequency, delta f0 Is Z f02 Residual angle of impedance angle, R d Is a single-phase grounding transition resistance.
9. The method of claim 8, wherein determining the fault condition of the neutral point-ungrounded system based on the comparison between the dielectric loss tangent to ground and the threshold value comprises:
determining a dielectric loss tangent to ground at a current signal at a reference frequency;
if the dielectric loss tangent value to the ground is larger than the threshold value, the neutral point non-grounding system has a grounding fault;
and if the dielectric loss tangent value to the ground is smaller than or equal to the threshold value, the neutral point is not grounded, and the system normally operates.
10. A fault sensing device for a neutral point ungrounded system, the device comprising:
the control unit is used for determining the capacitance value converted from the distribution network to the ground distributed capacitance to the secondary side of the electromagnetic voltage transformer PT and the distribution network to the ground distributed capacitance value through the injected detection current of the first frequency and the injected detection current of the second frequency;
the control unit is also used for determining the reference power distribution network impedance under the current signal of the reference frequency when the power distribution network normally operates and the grounding power distribution network impedance under the current signal of the reference frequency when the system is in single-phase grounding through the injected current signal of the reference frequency;
the control unit is further used for determining the parallel impedance of the capacitance converted from the power distribution network to the PT secondary side and the grounding transition resistance according to the capacitance value converted from the grounding distributed capacitance to the PT secondary side, the reference power distribution network impedance and the grounding power distribution network impedance;
the control unit is further used for determining a dielectric loss tangent value to the ground under a current signal injected with a reference frequency according to the parallel impedance of the capacitance of the power distribution network to the ground distributed capacitance converted to the PT secondary side and the ground transition resistance and the power distribution network to the ground distributed capacitance value;
and the fault judging unit is used for determining the fault state of the neutral point non-grounding system according to the comparison relation between the dielectric loss tangent value to the ground and the threshold value.
11. A computer device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the method of any of claims 1 to 9.
12. A computer readable storage medium storing a computer program which, when executed by a processor, causes the processor to perform the steps of the method of any one of claims 1 to 9.
CN202310576539.0A 2023-05-19 2023-05-19 Fault sensing method, device, equipment and medium for neutral point ungrounded system Pending CN116953422A (en)

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