WO2022121780A1 - 一种非有效接地系统单相接地的处理方法 - Google Patents

一种非有效接地系统单相接地的处理方法 Download PDF

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Publication number
WO2022121780A1
WO2022121780A1 PCT/CN2021/135184 CN2021135184W WO2022121780A1 WO 2022121780 A1 WO2022121780 A1 WO 2022121780A1 CN 2021135184 W CN2021135184 W CN 2021135184W WO 2022121780 A1 WO2022121780 A1 WO 2022121780A1
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Prior art keywords
phase
grounding
ground
controlled switch
current
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PCT/CN2021/135184
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English (en)
French (fr)
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薛占钰
丁同同
刘建伟
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保定钰鑫电气科技有限公司
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Priority to JP2023558924A priority Critical patent/JP2023554179A/ja
Priority to US18/265,805 priority patent/US20240039271A1/en
Priority to EP21902487.4A priority patent/EP4246747A4/en
Publication of WO2022121780A1 publication Critical patent/WO2022121780A1/zh

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
    • H02H3/162—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems
    • H02H3/165—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass for ac systems for three-phase systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/04—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
    • H02H3/042—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned combined with means for locating the fault
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/16—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass
    • H02H3/17—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to fault current to earth, frame or mass by means of an auxiliary voltage injected into the installation to be protected
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/261—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured involving signal transmission between at least two stations
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/22—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices
    • H02H7/226—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for distribution gear, e.g. bus-bar systems; for switching devices for wires or cables, e.g. heating wires
    • 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

Definitions

  • the invention relates to the field of power system fault processing, in particular to a processing method after a single-phase ground fault occurs in a non-effectively grounded system.
  • utility model patent CN 202815149 U provides an asymmetrical current source, by which a non-faulty phase can be grounded and short-circuited with the grounded phase to generate a short-circuit current, and then the current can pass through The detector shows the circuit where the short-circuit current is located and can quickly indicate the fault point.
  • the grounding resistance of single-phase grounding is difficult to predict. When the grounding resistance is too large, the short-circuit current is too small or even difficult to detect. If the grounding resistance is too small, the short-circuit current will be too large and a series resistance is required to prevent damage to the line , these problems greatly reduce the practicality of the method.
  • the purpose of the present invention is to provide a processing method for single-phase grounding of an ineffective grounding system, which can quickly locate the single-phase grounding fault point interval and automatically, quickly and accurately remove the fault, and can well improve the single-phase grounding fault. Process quality and improve power supply security.
  • the present invention adopts the following technical scheme: a method for processing single-phase grounding of an ineffectively grounded system, wherein a plurality of controlled switches are distributed on the non-effectively grounded system, and the controlled switches can detect each phase
  • the current pulse of the line can automatically cut off the line according to the number of current pulses, and the processing is as follows: (a) After a single-phase grounding occurs, a non-faulted phase or neutral point and the ground are cycled on and off to form the grounding phase.
  • connection and disconnection between the non-faulty phase and the ground is realized through a power electronic switch.
  • the power electronic switch is an insulated gate bipolar transistor.
  • the non-faulty phase is selected by the following method: after detecting the 3U 0 overrun by the voltage transformer and sensing the occurrence of a single-phase ground fault, the switch enables any The two phases are successively connected to the ground and then disconnected, and the phase with the larger current passing through the switch when it is connected to the ground is selected as the non-faulty phase.
  • the resistance of the closed loop when the resistance of the closed loop is relatively small, it is connected to the ground when the voltage phase angle is zero to obtain the current pulse with a relatively small peak value, or when the closed loop is closed When the resistance of the loop is relatively large, it is connected to ground at a voltage phase angle of 90 degrees to obtain the current pulse with a relatively large peak value.
  • the magnitude of the current pulse is monitored, and the power electronic switch is turned off when the instantaneous value of the current pulse reaches a preset value.
  • a ground point is selected on the non-faulty phase of the first controlled switch closest to the power supply on the side of the power supply to realize cyclic connection and disconnection with the ground, and the controlled switch is set on any phase.
  • the line is automatically cut off.
  • a ground point is selected on the non-faulty phase at any position below the first controlled switch closest to the power supply on any outlet line to realize cyclic connection and disconnection with the ground, and set the When the number of current pulses of any phase reaches the preset value, each controlled switch on the side of the grounding point away from the power supply will automatically cut off the line, and set the current of the controlled switch on the side of the grounding point close to the power supply in any two phases.
  • the circuit is automatically cut off when the number of pulses reaches the preset value; other outlet settings are set for the controlled switch to automatically cut off the circuit when the current pulse number of any phase reaches the preset value.
  • the non-effective grounding system is a two-phase power supply system or a three-phase power supply system.
  • the controlled switch can jump off in time when the condition for triggering cut-off is reached, so as to avoid the passage of the next current pulse.
  • the beneficial effect of the present invention is that after a single-phase grounding fault occurs, a non-faulty phase or a neutral point is grounded and then disconnected cyclically, which can form a grounding short-circuit loop with the grounded faulty phase and generate short-circuit current pulses.
  • the current pulse can be detected by the controlled switch on the line.
  • the controlled switch can cut off the controlled switch closest to the upper end of the single-phase grounding fault point according to the detected current pulse number and the preset number of trigger cut-off pulses, so as to cut off the single-phase grounding fault point. Phase-to-ground faults are automatically isolated.
  • power electronic switches such as insulated gate bipolar transistors can perform more immediate on-off control of the non-faulty phase-to-ground, so that a current pulse with short current time, as large current as possible, and more obvious characteristics can be produced, which is easier to be detected.
  • the controlled switch is accurately detected, and the size of the current pulse can be immediately detected by the current transformer connected in series with the power electronic switch. When the instantaneous value of the current pulse exceeds the limit, it can be cut off immediately to prevent the current pulse from triggering the overcurrent of each section of the line. protection and cause large-scale power outages.
  • FIG. 1 is a schematic diagram of the wiring of an embodiment of the method of the present invention
  • FIG. 2 is a schematic diagram of the wiring of another embodiment of the method of the present invention.
  • a three-phase power system is a common non-effective grounding system
  • a plurality of outgoing lines are arranged on the busbar of the three-phase electric power system
  • multiple controlled switches are arranged on each outgoing line
  • the controlled switch can detect the current pulses on each phase line, and can be set to cut off the three-phase line when the number of current pulses passing through any phase reaches the preset value, or can be set when the number of current pulses passing through any two phases reaches the preset value.
  • the three-phase line is only cut off when the preset value is set.
  • the controlled switch includes a control unit, a current detection unit and an execution unit, the current detection unit can detect the current of each phase of the three-phase line respectively, and the control unit detects the current detected by the current detection unit.
  • the number of pulses is compared with the preset value, and the current pulse number of any phase or the current pulse number of any two phases can be set to reach the preset value, and a signal is sent to make the execution unit cut off the three-phase line.
  • the preset value of the controlled switch downstream of the power supply direction is smaller than the preset value of the upstream direction of the power supply direction, the upstream direction of the power supply direction is relatively closer to the power source, and the downstream direction of the power source direction is relatively farther away from the power source , that is, electrical energy is emitted from the power source and transmitted from upstream to downstream.
  • the farther away from the power supply the smaller the preset value of the controlled switch to trigger and cut off, the easier it is to reach the trigger condition first and cut off.
  • the three phases of ABC are grounded above the first controlled switch 1 closest to the power supply, and the ground points are selected through the controlled switches KA, KB, KC Make the lines A, B, and C phases connected to the ground respectively.
  • the controlled switches KA, KB, KC Make the lines A, B, and C phases connected to the ground respectively.
  • set each controlled switch to detect that the number of current pulses of any phase reaches the preset value, and then the three-phase line is cut off.
  • the voltage transformers installed at KA, KB, and KC to collect the voltage of each phase (not shown in the figure, please refer to the utility model patent CN 202815149 U), and find that the single-phase grounding (for example, the C phase is at point F) through the 3U0 overrun Single-phase grounding), and then a non-faulty phase (such as A phase) is connected and disconnected from the ground above the first controlled switch 1, so that the non-faulty phase A above the switch KA will be connected to the power supply.
  • a grounding short circuit is created between the faulty phase C and the earth above point F, and short-circuit current pulses can be repeatedly generated, and the short-circuit current pulses only flow through the single-phase grounding fault point F on the faulty phase line.
  • Switches ie controlled switch 3, controlled switch 2 and controlled switch 1 without passing through the controlled switches (ie controlled switch 4 and controlled switch 5) below the single-phase ground fault point F.
  • the switch will automatically cut off, thereby automatically turning off the single-phase grounding fault. Ground fault removal.
  • the number of current pulses triggered and cut off is greater than that of the controlled switch 3, and the trigger conditions have not been fulfilled, so it will not be cut off. This ensures that the nearest controlled switch above the single-phase grounding fault point F is cut off, which not only ensures automatic troubleshooting, but also ensures the minimum power outage area.
  • the method is also applicable to two-phase systems or systems with more than three phases.
  • FIG. 2 illustrates another specific embodiment, in a three-phase system, optional two-phase switches are set, for example, the ground points of the two switches KB and KC are preset to the first controlled switch that is close to the power supply in any outgoing line Below, for example, between the controlled switch 4 and the controlled switch 5, and each controlled switch set above the ground point (ie, close to the power supply side), the three-phase current pulses of any two phases reach the preset value before cutting off the three-phase
  • the controlled switch below the grounding point (that is, away from the power supply side) is set to cut off the three-phase line when the number of current pulses of any phase reaches the preset value, and the other outgoing lines are set to the current of the controlled switch in any phase.
  • the line is automatically cut off when the number of pulses reaches a preset value. a. If the C-phase single-phase grounding occurs at point F, at this time, the switch KB of a non-faulty phase B is cyclically connected and disconnected to the ground to repeatedly generate current pulses in the grounding short circuit, because the controlled switch 5 is not It is connected to the short circuit, so there will be no action. With the increase of the number of current pulses, when the number of current pulses reaches the trigger number of the controlled switch 3, the controlled switch 3 will be cut off to eliminate the ground fault (although the controlled switch has been reached first before).
  • the controlled switch 4 needs to have two phases above the grounding points of the three switches KA, KB, and KC to reach the current pulse number, but actually only the non-faulty phase B has current pulses, and the faulty phase C is at the same time. There is no current pulse below the single-phase ground fault point F, so the controlled switch 4 will not cut off). b. If single-phase grounding occurs at point F', at this time, the controlled switch 5 detects that the number of current pulses of one phase reaches the preset value and can be cut off, thereby eliminating the fault.
  • a closed loop can also be formed in the manner of cyclic grounding and disconnection of the neutral point, instead of grounding the non-faulty phase.
  • the time interval between two adjacent current pulses needs to be greater than the tripping time of the controlled switch, so that it can be ensured that before the next current pulse is sent out, if the controlled switch reaches the cutoff condition, the tripping and cutoff will be completed, and the tripping will be avoided.
  • the controlled switch sends out multiple current pulses when it is not yet tripped, resulting in the undesired tripping of one or more controlled switches above the controlled switch that should be tripped, resulting in unreasonable large-scale power outages .
  • a power electronic switch such as an insulated gate bipolar transistor, is used to achieve short-time cyclic grounding and disconnecting.
  • insulated gate bipolar transistors can withstand high power switching on and off, and respond in microseconds, producing short-circuit current pulses of several milliseconds in duration.
  • the power electronic switch By detecting the voltage signal of the voltage transformer (PT), it can be judged that the ground fault has been eliminated, and the power electronic switch can be grounded and disconnected again to send one more pulse. At this time, the power electronic switch should be used with the current transformer (CT). , When a controlled switch is cut off after a certain pulse, then another pulse is sent. If the current transformer of the power electronic switch cannot detect the short-circuit current, it means that a controlled switch has tripped, and the fault is eliminated. Stop the non-faulted phase to ground.
  • the non-faulty phase can be judged to realize the non-faulty phase closing. If it is judged that the single-phase grounding occurs, but it is not possible to accurately judge which two phases are non-faulty phases, the non-faulty phases can be judged by the following method: Make any two phases ground and disconnect through the electronic power switch successively, and the result will be obtained twice current pulses (one of which may be very small), and then select the phase with the largest current pulse when grounding as the non-faulty phase to start cyclic grounding and disconnecting operations.
  • the phase is a single-phase ground fault phase
  • the other operation must be a non-fault phase, and the current is relatively large. If both operations are non-fault phases, select the relatively large current. Also a non-faulty phase.
  • the even on-off performance of the power electronic switch can be used to set the current detection device to detect the instantaneous value of the current pulse.
  • the instantaneous value of the current pulse is When the value is too large and exceeds the preset value, the circuit will be cut off in time to avoid triggering the overcurrent protection.
  • a current limiting resistor can also be connected in series. In addition, by using PT to detect 3U 0 , the grounding resistance can be judged.
  • the power electronic switch can be set to be turned on when the voltage phase angle is zero, so that no excitation current will be generated, and the short-circuit current will not be increased.
  • a series resistor can also be used.
  • the grounding resistance is large, it can be turned on when the voltage phase angle is 90 degrees, which will generate excitation current and increase the peak value of the short-circuit current, which is conducive to detection.
  • the magnitudes of the grounding short-circuit loop resistance and the short-circuit current are analyzed and judged according to the specific detection environment, and are mastered by those skilled in the art.
  • the short-circuit circuit resistance makes the short-circuit current so small that it is inconvenient to detect, it should be selected to close the switch near the voltage phase angle of 90 degrees to increase the current detection degree; when the grounding short-circuit circuit resistance is small, the current is too large and the equipment may be burned.
  • the instantaneous value of the current pulse reaches the preset value, it can be cut off in time, or it can be closed when the voltage phase angle is zero to avoid increasing the current, and at the same time, it is equipped with current monitoring.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Emergency Protection Circuit Devices (AREA)

Abstract

一种非有效接地系统单相接地的处理方法，发生单相接地后，将一非故障相或中性点与大地循环接通和断开以与接地相形成闭合回路并重复产生电流脉冲；利用受控开关（1，2，3，4，5）检测所述电流脉冲，并设定电源方向下游的受控开关（4，5）触发切断的电流脉冲数少于电源方向上游的受控开关（1，2，3）触发切断的电流脉冲数；当某一受控开关（1，2，3，4，5）在达到触发条件切断后，停止所述非故障相接地。该方法可以快速定位单相接地故障点区间并能自动、快速、准确的切除故障，可以很好提升单相接地故障的处理质量，提升供电安全。

Description

一种非有效接地系统单相接地的处理方法 技术领域
本发明涉及电力系统故障处理领域，具体涉及一种非有效接地系统发生单相接地故障后的处理方法。
 背景技术
当非有效接地系统（如三相供电系统）发生单相接地时，一般按如下步骤进行处理：1、查找故障线路；2、停掉故障线路；3、查找并排除故障点；4、恢复供电。这种处理方法往往存在查找故障点慢，停电时间长，停电面积大等弊端，而且在排除故障前单相接地持续时间较长，对外界存在着危险。为了解决这一问题，实用新型专利CN202815149 U提供了一种不对称电流源，利用该不对称电流源可以使一非故障相接地并与接地相形成短路从而产生短路电流，然后通过电流检测器显示短路电流所在回路可以快速指示故障点。但是在使用中发现，单相接地时的接地电阻大小难以预测，接地电阻过大时短路电流太小甚至难以检测，接地电阻太小时会使短路电流过大而需要串联电阻以防对线路造成损害，这些问题极大降低了该方法的实用性。一个改进的思路是使短路电流持续时间很短，这样无需串入限流电阻也不会对线路造成损害，而且不串入限流电阻还会使短路电流尽可能大从而容易被检出，因此会增强上述方法的实用性（如CN 110634713 A、CN 110531822 A、CN 209822486 U都是为制造短时电流而提出的专利申请）。但即使如此，上述方法也仅是有助于指示出单相接地故障点，实际查找该故障点仍然较为费时，单相接地故障持续时间较长的危害仍然存在。如何自动快速地将单相接地故障点切除出非有效接地系统，尽可能缩小停电面积，缩短单相接地的持续时间从而减小危害，是本领域期望解决的技术问题。
 技术问题
本发明的目的是提供一种非有效接地系统单相接地的处理方法，该方法可以快速定位单相接地故障点区间并能自动、快速、准确的切除故障，可以很好提升单相接地故障的处理质量，提升供电安全。
 技术解决方案
为了实现上述目的，本发明采取如下技术方案：一种非有效接地系统单相接地的处理方法，在所述非有效接地系统上分布有多把受控开关，所述受控开关能够检测各相线路的电流脉冲并可以根据电流脉冲数自动切断线路，按如下步骤处理：（a）发生单相接地后，将一非故障相或中性点与大地循环接通和断开以与接地相形成闭合回路并重复产生电流脉冲；（b）利用所述受控开关检测所述电流脉冲，并设定电源方向下游的受控开关触发切断的电流脉冲数少于电源方向上游的受控开关触发切断的电流脉冲数；当某一受控开关在达到触发条件切断后，停止所述非故障相接地。
优选的，所述步骤（a）中，通过电力电子开关实现所述非故障相与大地的接通和断开。
优选的，所述电力电子开关为绝缘栅双极型晶体管。
优选的，将所述非故障相与大地循环接通和断开前，通过如下方法选择所述非故障相：通过电压互感器检测3U 0超限感知发生单相接地故障后，通过开关使任意两相先后与大地接通再断开，并选择与大地接通时通过所述开关电流较大的一相作为所述非故障相。
优选的，所述步骤（a）中，当所述闭合回路的电阻相对较小时，在电压相角为零时与大地接通以获得峰值相对较小的所述电流脉冲，或者当所述闭合回路的电阻相对较大时，在电压相角为90度时与大地接通以获得峰值相对较大的所述电流脉冲。
优选的，监测所述电流脉冲的大小，当电流脉冲的瞬时值达到预设值时即切断所述电力电子开关。
优选的，在距离电源最近的第一把受控开关的靠近电源一侧的所述非故障相上选取接地点来实现与大地的循环接通和断开，设置所述受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路。
优选的，在任意一条出线上距离电源最近的第一把受控开关以下的任意位置的所述非故障相上选取接地点来实现与大地的循环接通和断开，设置该出线上所述接地点远离电源一侧的各把受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路，设置所述接地点靠近电源一侧的受控开关在任意两相的电流脉冲数均达到预设值时才自动切断所述线路；其他出线设置所述受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路。
优选的，所述非有效接地系统为两相供电系统或三相供电系统。
优选的，所述受控开关在达到触发切断的条件时能够及时跳开，以避免下一个电流脉冲通过。
 有益效果
本发明有益效果在于：单相接地故障发生后，循环将一非故障相或将中性点接地后再断开，可与已接地的故障相形成接地短路回路并产生短路电流脉冲，该重复产生的电流脉冲能够被线路上的受控开关检测，受控开关可以根据检测到的电流脉冲数和预设的触发切断脉冲数将距离单相接地故障点上端最近的受控开关切断，从而将单相接地故障自动隔离。采用绝缘栅双极型晶体管等电力电子开关，可以对非故障相接地进行更即时的通断控制，由此可以制造出电流时间短、电流尽量大、特征更明显的电流脉冲，更容易被受控开关准确检测到，而且还可以通过与电力电子开关串联的电流互感器即时检测电流脉冲的大小，当电流脉冲瞬时值超出限值时可以立即切断，防止电流脉冲触发线路的各段过流保护而造成大面积停电。
 附图说明
图1是本发明方法一实施例接线示意图；图2是本发明方法另一实施例接线示意图。
 本发明的实施方式
下面结合附图，通过具体实施例对本发明做进一步说明：三相电力系统是常见的非有效接地系统，在三相电力系统的母线上设置多条出线，各出线上设置多把受控开关，受控开关能够检测各相线路上的电流脉冲，并可以设置当通过任一相的电流脉冲数达到预设值时即切断三相线路，或者可以设置当通过任意两相的电流脉冲数均达到预设值时才切断三相线路。在一个关于受控开关的具体实施例中，受控开关包括控制单元，电流检测单元和执行单元，电流检测单元可以分别检测三相线路的各相电流，控制单元将电流检测单元检测到的电流脉冲数目与预设值进行比较，可以设置任一相的电流脉冲数或任意两相的电流脉冲数达到预设值时就发出信号使执行单元切断三相线路。针对触发切断的电流脉冲数的预设值，处于电源方向下游的受控开关的预设值小于电源方向上游的预设值，电源方向上游即相对更靠近电源，电源方向下游即相对更远离电源，也即电能从电源发出并由上游向下游传输。或者说，按电源方向的上下游看，距离电源越远的受控开关触发切断的预设值越小，越容易先达到触发条件从而切断。
如图1所示，在一个具体实施例中，ABC三相（或至少其中两相）均在距离电源最近的第一把受控开关1以上选取接地点，通过受控开关KA 、KB、KC使得线路A、B、C相分别与大地相连，此时设定各把受控开关检测到任一相的电流脉冲数达到预设值即切断三相线路。利用在KA、KB、KC处安装的电压互感器采集各相电压（附图未示出，可参考实用新型专利CN202815149 U），通过3U0超限发现单相接地（例如C相在点F单相接地），然后将一非故障相（如A相）在第一把受控开关1以上循环与大地接通、断开，这样就会在开关KA以上处的非故障相A相与电源、点F以上的故障相C相、大地之间制造出一个接地短路回路，并且可以重复产生短路电流脉冲，该短路电流脉冲在故障相线路上只流过单相接地故障点F以上的受控开关（即受控开关3、受控开关2和受控开关1），而不会通过单相接地故障点F以下的受控开关（即受控开关4和受控开关5）。这样随着循环接地、断开的操作持续，当短路电流脉冲的数目达到单相接地故障点以上最近的受控开关3的预设值时，该把开关即会自行切断，从而自动将单相接地故障排除。虽然单相接地故障点F以下的受控开关4、5的触发切断的电流脉冲数小，但是因为它们没有接入接地短路回路，因此不会有切断动作，而受控开关2、受控开关1等虽然接入接地短路回路，但是其触发切断的电流脉冲数大于受控开关3，触发条件未成就，所以也不会切断。这样就保证了单相接地故障点F以上最近的一把受控开关切断，既保证自动排除故障，又保证了停电面积最小。本方法也适用于两相系统或多于三相的系统。
图2示例出另一种具体实施例，在三相系统上任选两相设置开关，如将两把开关KB和KC的接地点预设置在任一条出线的靠近电源最近的第一把受控开关以下，如受控开关4和受控开关5之间，并且设置该接地点以上（即靠近电源侧）的各把受控开关要任意两相的电流脉冲均达到预设值时才切断三相线路，而该接地点以下（即远离电源侧）的受控开关则设置任一相的电流脉冲数达到预设值时即切断三相线路，其他出线设置所述受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路。a、假如在点F发生C相单相接地，此时将一非故障相B的开关KB循环与大地接通和断开，以在接地短路回路中重复产生电流脉冲，因受控开关5未接入短路回路，所以不会有动作，随着电流脉冲数的增加，当电流脉冲数达到受控开关3的触发数时，受控开关3切断从而排除接地故障（虽然此前先达到受控开关4的电流脉冲数，但因受控开关4在三把开关KA、KB、KC的接地点以上需要有两相同时达到电流脉冲数，而实际只有非故障相B有电流脉冲，故障相C在单相接地故障点F以下没有电流脉冲，所以受控开关4不会切断）。b、假如在点F’发生单相接地，此时受控开关5检测到有一相的电流脉冲数达到预设值即可切断，从而排除故障。
上述实施例中，也可以采取中性点循环接地断开的方式形成闭合回路，而不将非故障相接地。
上述实施例中，相邻两个电流脉冲的时间间隔需要大于受控开关的跳开耗时，这样可以确保下一个电流脉冲发出前如有受控开关达到切断条件会完成跳开切断，避免在受控开关未及跳开时又发出多个电流脉冲从而导致应该跳开的受控开关以上一把或多把受控开关也发生不期望的跳开，并由此造成不合理的大面积停电。
在一个具体实施例中，采用电力电子开关，如绝缘栅双极型晶体管，来实现短时间的循环接地、断开。目前绝缘栅双极型晶体管能够承受大功率的接通和断开，并且是微秒级响应，可以制造出几个毫秒时长的短路电流脉冲。
通过电压互感器（PT）检测电压信号可以判断已排除接地故障，也可以使电力电子开关再进行一次接地、断开操作从而多发一次脉冲，此时电力电子开关应配合电流互感器（CT）使用，当某一次脉冲后有受控开关切断，此时再多发一次脉冲，如果电力电子开关的电流互感器检测不到短路电流，说明某一受控开关已经跳开，故障排除，此时即可停止非故障相接地。
如前所述，可以通过PT检测单相接地故障的发生并判断出非故障相从而实现非故障相合闸。如果虽然判断出单相接地发生，但是并不能准确判断哪两相是非故障相时，可以通过如下方法判断非故障相：使任意两相先后分别通过电子电力开关接地、断开，会得到两次电流脉冲（其中一次可能电流很小），然后选择接地时电流脉冲大的那一相作为非故障相开始循环接地、断开操作。因为如果一次操作的电流很小，说明该相为单相接地故障相，则另一次操作的肯定是非故障相，电流比较大，如果两此操作的都是非故障相，则选择电流相对大的肯定也是非故障相。
因为单相接地故障点的随机发生，会导致接地短路回路中电阻大小随机出现，当出现小电阻时，短路电流脉冲会较大，甚至会对电源设备造成损害并触发三相系统故障线路出口断路器的一段、二段等过流保护而造成大面积停电，为了避免这种可能性，可利用电力电子开关的即使通断性能，设置电流检测装置检测电流脉冲的瞬时值，当电流脉冲的瞬时值过大超过预设值时及时切断电路，从而避免触发过流保护。也可以串联限流电阻。此外，利用PT检测3U 0，可以判断接地电阻大小，当接地电阻较小时，可以设置电力电子开关在电压相角为零的时候导通，这样不会产生激励电流，避免对短路电流增大，使电流脉冲峰值相对较小，亦可以采用串入电阻的方式。当接地电阻较大时，可以在电压相角为90度时导通，这样会产生激励电流，使短路电流峰值增大，有利于检测。接地短路回路电阻和短路电流的大小根据具体的检测环境来分析判断，为本领域技术人员所掌握。当短路回路电阻大致使短路电流小到不便于检测时应该选用在电压相角90度附近合闸，以增大电流提升检出度；当接地短路回路电阻小致使电流过大以致有可能烧毁设备时，可以检测电流脉冲的瞬时值达到预设值时及时切断或者采用在电压相角为零时合闸以避免增大电流，同时配以电流监测。
上述实施例只是对本实用新型构思和实现的若干说明，并非对其进行限制，在本实用新型构思下，未经实质变换的技术方案仍然在保护范围内。
 工业实用性
通过在三相供电系统中进行实验，上述方法完全可行。

Claims (10)

  1. 一种非有效接地系统单相接地的处理方法，其特征在于：
    在所述非有效接地系统上分布有多把受控开关，所述受控开关能够检测各相线路的电流脉冲并可以根据电流脉冲数自动切断线路，按如下步骤处理：
    （a）发生单相接地后，将一非故障相或中性点与大地循环接通和断开以与接地相形成闭合回路并重复产生电流脉冲；
    （b）利用所述受控开关检测所述电流脉冲，并设定电源方向下游的受控开关触发切断的电流脉冲数少于电源方向上游的受控开关触发切断的电流脉冲数；当某一受控开关在达到触发条件切断后，停止所述非故障相接地。
  2. 如权利要求1所述的非有效接地系统单相接地的处理方法，其特征在于，所述步骤（a）中，通过电力电子开关实现所述非故障相与大地的接通和断开。
  3. 如权利要求2所述的非有效接地系统单相接地的处理方法，其特征在于，所述电力电子开关为绝缘栅双极型晶体管。
  4. 如权利要求1所述的非有效接地系统单相接地的处理方法，其特征在于，将所述非故障相与大地循环接通和断开前，通过如下方法选择所述非故障相：通过电压互感器检测3U 0超限感知发生单相接地故障后，通过开关使任意两相先后与大地接通再断开，并选择与大地接通时通过所述开关电流较大的一相作为所述非故障相。
  5. 权利要求1所述的非有效接地系统单相接地的处理方法，其特征在于，所述步骤（a）中，当所述闭合回路的电阻相对较小时，在电压相角为零时与大地接通以获得峰值相对较小的所述电流脉冲，或者当所述闭合回路的电阻相对较大时，在电压相角为90度时与大地接通以获得峰值相对较大的所述电流脉冲。
  6. 如权利要求2所述的非有效接地系统单相接地的处理方法，其特征在于，监测所述电流脉冲的大小，当电流脉冲的瞬时值达到预设值时即切断所述电力电子开关。
  7. 如权利要求1至6任一项所述的非有效接地系统单相接地的处理方法，其特征在于，在距离电源最近的第一把受控开关的靠近电源一侧的所述非故障相上选取接地点来实现与大地的循环接通和断开，设置所述受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路。
  8. 如权利要求1至6任一项所述的非有效接地系统单相接地的处理方法，其特征在于，在任意一条出线上距离电源最近的第一把受控开关以下的任意位置的所述非故障相上选取接地点来实现与大地的循环接通和断开，设置该出线上所述接地点远离电源一侧的各把受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路，设置所述接地点靠近电源一侧的受控开关在任意两相的电流脉冲数均达到预设值时才自动切断所述线路；其他出线设置所述受控开关在任一相的电流脉冲数达到预设值时即自动切断所述线路。
  9. 如权利要求7所述的非有效接地系统单相接地的处理方法，其特征在于，所述非有效接地系统为两相供电系统或三相供电系统。
  10. 如权利要求1所述的非有效接地系统单相接地的处理方法，其特征在于，所述受控开关在达到触发切断的条件时能够及时跳开，以避免下一个电流脉冲通过。
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