CN103645418A - Earth fault line selector for transformer station direct current system - Google Patents

Abstract

The invention discloses an earth fault line selector for a transformer station direct current system. The earth fault line selector comprises a signal generation source (1), a primary coil (2), a secondary coil (3), an O-shaped magnet ring (4) and a Hall sensing element (5), wherein the primary coil (2) and the secondary coil (3) are wound on the O-shaped magnet ring (4); the Hall sensing element (5) is installed in the O-shaped magnet ring (4); and the signal generation source (1) is connected with the primary coil (2), and thus the earth fault line selector is formed wholly. By utilizing the effective combination of the primary coil and the secondary coil and with the cooperation of the Hall sensing element, the finding, analyzing and positioning of a DC earth fault branch are achieved without the influence of the positive and negative earth capacitance and without the influence of external signals; and the earth fault line selector has the advantages of complete data and quick detection.

Description

Transformer station direct current system earth fault line selection device

Technical field

The present invention relates to transformer station direct current system earth fault line selection device, particularly for DC system earth fault branch road, search the measurement of patrolling and examining.

Technical background

It is mainly measurement and the location that is applied to the DC current system earth trouble spot of transformer station, generating plant that DC system grounding is searched, and straight-flow system is a complicated multiple-limb supply network because branch is wide, branch feeder is many, ground connection is complicated, DC wire distribution form is various.Some faults usually occur in cable duct, have out of doors, have in protection screen cabinet.All mixing with cable, communication cable, high-tension cable with protection usually appears in direct current power supply loop, and along with dust, humidity, insulation decline, the continuous appearance of the phenomenon such as aging, insulation fault just unavoidably.Search DC ground fault loop, get rid of earth fault except artificial loop power failure method, have a power failure and get rid of classic method one by one, having occurred in recent years having adopted with DC earthing line-selected earthing device the modes such as double frequency injection method, low frequency injection method to judge, is mainly to measure in trouble spot and utilized and injected the method that AC signal is measured leakage current based on DC earthing.Utilization is installed on the sensor of each direct current branch; sensor sensing is injected into the ac leakage stream signal in DC power system; this method can be judged the fault loop of DC earthing effectively; owing to injecting AC signal, after straight-flow system, can bring certain harmful effect to straight-flow system and protection equipment; may also can cause and exchange the capacitance current that capacitive earth current causes, the mistake causing is surveyed and misjudgment phenomenon simultaneously.Also occurred in recent years the applications exploiting Hall element induction leakage current principle of the sensor technology of magnetic saturation method principle, hall sensing principle.Limitation due to magnetic induction and single hall sensing technology, cause earth fault cannot comprehensively judge localization of fault, as the earth fault of same direction earth fault and same polarity cannot accurately be judged, cause hall principle sensor is the unicity for the Monitoring Data of the leakage current of DC current always, and is vulnerable to the shortcomings such as interference.

Summary of the invention

The object of the invention is to: a kind of transformer station direct current system earth fault line selection device is provided, for DC system earth fault branch road, searches and patrol and examine measurement, simple in structure, easy to operate, avoid interference, search and patrol and examine accurately, intuitive display.

Technical solution of the present invention is: this earth fault line selection device comprises signal generating source, primary coil, secondary coil, O type magnet ring and hall sensing element, primary coil and secondary coil are wound on O type magnet ring, hall sensing element is installed in O type magnet ring, signal generating source and primary coil join, whole formation earth fault line selection device.

When troubleshooting is patrolled and examined, two wires of both positive and negative polarity on direct current branch road are through O type magnet ring, the electromagnetic wave signal that signal generating source produces is added on primary coil, secondary coil senses the electromagnetic wave of primary coil, secondary coil senses that primary coil electromagnetic wave also can be subject to the effect of signals in the magnetic field of the DC circuit leakage current generating by O type magnet ring, and the electromagnetic waveform that secondary coil senses just can be distinguished direction and the DC loop both positive and negative polarity leakage current polarity of leakage current; The signal in the magnetic field of DC circuit leakage current generating makes the electromagnetic field of O type magnet ring that electromagnetic change occur, hall sensing element will sense the electromagnetic field of O type magnet ring, the size of electromagnetic field is leakage current namely, and hall sensing element just can measure the leakage current amplitude through O type magnetic ring coil direct current both positive and negative polarity loop effectively.

The present invention adopts effective combination of primary coil and secondary coil, under hall sensing element collaborative, realize and effectively search the location of analyzing DC ground fault branch road, be not subject to the impact of positive and negative ground capacitance, be not subject to the interference of external signal, have data complete, measure fast feature.

Accompanying drawing explanation

Fig. 1 is structural representation of the present invention.

Fig. 2 is primary coil and the secondary coil oscillogram of Fig. 1.

In figure: 1 signal generating source, 2 primary coils, 3 secondary coils, 4 O type magnet rings, 5 hall sensing elements, 6 direct current branch roads.

Embodiment

As shown in Figure 1, this earth fault line selection device comprises signal generating source 1, primary coil 2, secondary coil 3, O type magnet ring 4 and hall sensing element 5, primary coil 2 is wound on O type magnet ring 4 with secondary coil 3, hall sensing element 5 is installed in O type magnet ring 4, signal generating source 1 joins with primary coil 2, whole formation earth fault line selection device.

During installation, two wires of direct current branch loop 6 both positive and negative polarities are through O type magnet ring, when direct current branch loop does not have leakage current signal to produce, occur in the absence of earth fault, the size of current of its both positive and negative polarity is identical, opposite direction, can not produce residual current, the magnetic field of O type magnet ring can not change, the primary coil and the secondary coil signal that are wound on O type magnet ring can not be subject to the influence of magnetic field of O type magnet ring simultaneously, the signal that secondary coil signal and primary coil two ends produce is provided by signal generating source, and secondary coil senses that the electromagnetic signal waveform of primary coil is consistent, direct current branch loop if there is leakage current signal both positive and negative polarity electric current inconsistent, the electromagnetic wave signal primary coil that signal generating source occurs is constant, the magnetoelectricity signal that secondary coil senses will be subject to the impact of leakage current field signal, and obvious variation has occurred waveform, direct current branch loop is if there is leakage current signal, while also there is obvious variation in the electromagnetic field of O type magnet ring, hall sensing element changes the electromagnetic field that senses O type magnet ring, if just changed O type magnet ring electromagnetic field during positive and negative two wire residual currents generation of passing O type magnet ring, at this moment primary coil also can sense the induced voltage of leakage current, hall sensing element also senses the changes of magnetic field of O type magnet ring, hall sensing element captures the magnetic field of residual current generation and calculates strength of current, namely hall sensing element can judge the size of current of DC system grounding, there is variation in the waveform of the primary coil that secondary coil senses, according to the wave form varies measuring, just can effectively distinguish direction and the polarity that leakage current occurs, hall sensing element senses, to the variation in the magnetic field of O type magnet ring, induces the size of leakage current, namely occurs the size of DC ground fault grounding resistance, so just can effectively solve failure point of DC grounding.

As shown in Figure 2, be primary coil and secondary coil oscillogram, the oscillogram of primary coil is to consist of triangular wave, is to be provided by signal generating source, primary coil generation triangular wave, frequency is 20HZ, complete signal source is added on primary coil its waveform as shown in A, secondary coil also will receive triangular wave, if while not having unnecessary electric current to flow through through the wire of O type magnet ring, secondary coil is also by the triangular wave of receiving that a frequency is 20HZ, its waveform is the same with primary coil, as consistent in B, if while having unnecessary electric current to flow through through the wire of O type magnet ring, the information waveform that secondary coil senses will occur significantly to change, if the current waveform that secondary coil senses and primary current oscillogram compare, if there is secondary coil waveform phase leading represent during primary coil with the magnetic field superposition through O type magnet ring wire leakage current generating to the waveform of primary coil, as shown in C, its direction is consistent with primary coil waveform magnetic field, and expression is that anodal rear end has leakage current generating, if there is secondary coil waveform phase represent to have offseted with the magnetic field through O type magnet ring wire leakage current generating the waveform of primary coil while having lagged behind primary coil, as shown in D, its direction is contrary with primary coil waveform magnetic field, and expression is that the rear end of negative pole has leakage current generating, the magnetic field that its leakage current signal produces causes the variation of secondary coil output waveform, be that current signal that leakage current secondary coil senses indicates with consistent through O type magnet ring current in wire direction while being less than by secondary coil, represent that leakage current signal is consistent with secondary coil, leakage current just can judge the front-end and back-end that occur in O type magnet ring, can effectively judge the direction of earth fault, in conjunction with Hall original paper, export, can know anodal negative pole polarity and earthing fault direction that earth fault occurs, and the size of earth leakage stream, the size of grounding resistance namely.

Claims (1)

1. transformer station direct current system earth fault line selection device, it is characterized in that: this earth fault line selection device comprises signal generating source (1), primary coil (2), secondary coil (3), O type magnet ring (4) and hall sensing element (5), primary coil (2) is wound on O type magnet ring (4) with secondary coil (3), hall sensing element (5) is installed in O type magnet ring (4), signal generating source (1) joins with primary coil (2), whole formation earth fault line selection device.

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